CN102055335B

CN102055335B - Buck-boost power converter and control method thereof

Info

Publication number: CN102055335B
Application number: CN200910212078.9A
Authority: CN
Inventors: 陈科宏; 吴纬权; 何心欣
Original assignee: Richtek Technology Corp
Current assignee: Richtek Technology Corp
Priority date: 2009-11-03
Filing date: 2009-11-03
Publication date: 2015-08-12
Anticipated expiration: 2029-11-03
Also published as: CN102055335A

Abstract

A kind of control method of buck-boost power converter, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, between the first end that one second switch is connected to described inductance and an earth terminal, between the second end that one the 3rd switch is connected to described inductance and described earth terminal, and one the 4th switch be connected between the second end of described inductance and the output of described power supply changeover device, it is characterized in that described control method comprises the following steps: to detect the voltage on described input and output and the load current on described output to determine that described power supply changeover device operates in decompression mode, first buck-boost mode, second buck-boost mode or boost mode, when first and second buck-boost mode described, control described first, second, third and the 4th switch.

Description

Buck-boost power converter and control method thereof

Technical field

The present invention relates to a kind of power supply changeover device, specifically, is a kind of buck-boost power converter and control method thereof of improving switch cost and correct switch mode.

Background technology

Fig. 1 shows known buck-boost power converter 10, and it comprises power stage 12 and control circuit 14.In power stage 12, interrupteur SW 1 is connected between input voltage vin and inductance L, and interrupteur SW 2 is connected between inductance L and earth terminal GND, and interrupteur SW 3 is connected between inductance L and earth terminal GND, and interrupteur SW 4 is connected between inductance L and output voltage Vout.Resistance R1 and R2 pressure-dividing output voltage Vout produces feedback signal VFB, in control circuit 14, error amplifier 24 produces error signal VEA according to feedback signal VFB and reference voltage Vref, sawtooth generator 22 provides two sawtooth signal SAW1 and SAW2, comparator 18 comparison error signal VEA and sawtooth signal SAW1 produces signal PWM1, comparator 20 comparison error signal VEA and sawtooth signal SAW2 produces signal PWM2, control logic circuit 16 produces signal VA according to signal PWM1 and PWM2, VB, VC and VD be diverter switch SW1 respectively, SW2, SW3 and SW4 is to transfer input voltage vin to output voltage Vout.When error signal VEA only switches to sawtooth signal SAW1 or SAW2, power supply changeover device 10 operates in decompression mode or boost mode, and when error signal VEA switches to two sawtooth signal SAW1 or SAW2, power supply changeover device 10 operates in buck-boost mode.But, in fact, the waveform of sawtooth signal SAW1 and SAW2 is not ideal linearity at peak value and valley, therefore, when input voltage vin is close to output voltage Vout, namely signal PWM1 or PWM2 responsibility cycle ratio (duty ratio) close to 100% time, the ripple of output voltage Vout will be made to become large because of nonlinear problem.

The people such as Chen are at U.S. Patent number the 7th, 176, in No. 667, a kind of buck-boost power converter is proposed, it is when buck-boost mode, a sawtooth signal and error signal is utilized to cut out the responsibility cycle of required buck or boost, and the boosting that insertion one is fixing within described responsibility cycle or step-down responsibility cycle.But, no matter be the power supply changeover device that the people such as Fig. 1 or Chen propose, when buck-boost mode, the switching circulation of switch is opened (turn on) interrupteur SW 2 and SW4 for (1) and closes (turn off) interrupteur SW 1 and SW3, (2) interrupteur SW 1 and SW4 is opened and closing switch SW2 and SW3, (3) interrupteur SW 1 and SW3 is opened and closing switch SW2 and SW4, (4) interrupteur SW 1 and SW4 is opened and closing switch SW2 and SW3, because the number of times of switching over is in each cycle more, therefore switch cost (switching loss) is also larger.

Therefore known buck-boost power converter also exists above-mentioned all inconvenience and problem.

Summary of the invention

Object of the present invention, be to propose a kind of at input voltage close to using new switching sequence during output voltage, reduce buck-boost power converter and the control method thereof of switch cost and conduction losses.

Another object of the present invention, be to propose a kind of at input voltage close to extending the switching cycle of switch during output voltage to reduce buck-boost power converter and the control method thereof of switch cost.

Another object of the present invention, is to propose a kind ofly to consider that the impact of load current on buck responsibility cycle makes it correctly can put switch mode, and therefore output voltage can not because of for a change pattern and affected buck-boost power converter and control method thereof.

For achieving the above object, technical solution of the present invention is:

A kind of control method of buck-boost power converter, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, between the first end that one second switch is connected to described inductance and an earth terminal, between the second end that one the 3rd switch is connected to described inductance and described earth terminal, and one the 4th switch be connected between the second end of described inductance and the output of described power supply changeover device, it is characterized in that described control method comprises the following steps:

First step: detect the voltage on described input and output and the load current on described output to determine that described power supply changeover device operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode;

Second step: when first and second buck-boost mode described, described first, second, third and the 4th the control of switch comprise:

A () closes described first switch, open described second switch, closes described 3rd switch, opens described 4th switch;

B () opens described first switch, close described second switch, maintains described 3rd switch and closes, maintain described 4th switch opens;

C () maintains described first switch opens, maintain described second switch and close, open described 3rd switch, close described 4th switch.

The control method of buck-boost power converter of the present invention can also be further achieved by the following technical measures.

Aforesaid control method, the step that the described power supply changeover device of wherein said decision operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode comprises the following steps:

First step: the multiplier value when the described inductance two ends that the voltage on described input and output and load current determine is less than one first critical value, determines that described power supply changeover device operates in decompression mode;

Second step: the multiplier value when the described inductance two ends that the voltage on described input and output and load current determine is greater than described first critical value and is less than one second critical value, determines that described power supply changeover device operates in described first buck-boost mode;

Third step: the multiplier value when the described inductance two ends that the voltage on described input and output and load current determine is less than one the 3rd critical value and is greater than described second critical value, determines that described power supply changeover device operates in described second buck-boost mode;

4th step: when the multiplier value at the described inductance two ends that the voltage on described input and output and load current determine is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

Aforesaid control method, wherein more comprises:

Amplify one first letter and and a reference voltage between difference produce a secondary signal, described first signal is the function of voltage on described output;

One first frequency and a second frequency are provided;

One the 3rd signal and one the 4th signal is produced according to the operator scheme of described power supply changeover device and described first frequency;

More described secondary signal and the 3rd signal produce one the 5th signal;

More described secondary signal and the 4th signal produce one the 6th signal;

Described first, second, third and the 4th switch is controlled according to the operator scheme of described power supply changeover device, the described 5th and the 6th signal, first frequency and second frequency.

Aforesaid control method, wherein when described decompression mode, the switching cycle of first and second switch described is a period 1; Described in when described first buck-boost mode first, second, third and the 4th the switching cycle of switch be a second round being greater than the described period 1; Described in when described second buck-boost mode first, second, third and the 4th the switching cycle of switch be a period 3 being greater than the described period 1; The switching cycle of the 3rd and the 4th switch described in when described boost mode is a period 4 being less than second and third cycle described.

Aforesaid control method, wherein when described first buck-boost mode, the responsibility cycle of the described 3rd and the 4th switch is fixed.

Aforesaid control method, wherein when described second buck-boost mode, the responsibility cycle of first and second switch described is fixed.

A kind of buck-boost power converter, is characterized in that, comprising:

One inductance;

One first switch, is connected between the input of described power supply changeover device and the first end of described inductance;

One second switch, between the first end being connected to described inductance and an earth terminal;

One the 3rd switch, between the second end being connected to described inductance and described earth terminal;

One the 4th switch, is connected between the second end of described inductance and the output of described power supply changeover device;

One control circuit, control described first, second, third and the 4th switching of switch, and determine that described power supply changeover device operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode according to the load current on the voltage on described input and output and described output;

Wherein, when first and second buck-boost mode described, described first, second, third and the 4th the control of switch comprise (a) and close described first switch, open described second switch, close described 3rd switch and open described 4th switch, b () is opened described first switch, closes described second switch, is maintained described 3rd switch closedown and maintain described 4th switch opens, and (c) maintains described first switch opens, maintains the closedown of described second switch, open described 3rd switch and close described 4th switch.

Aforesaid power supply changeover device, when the multiplier value at the described inductance two ends that the voltage of wherein said control circuit on described input and output and described load current determine is less than first critical value, determine that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the voltage on described input and output and described load current determine is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the voltage on described input and output and described load current determine is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the voltage on described input and output and load current determine is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

Aforesaid power supply changeover device, wherein said control circuit comprises:

One error amplifier, produces a secondary signal according to one first signal and a reference voltage, and described first signal is the function of voltage on described power supply changeover device output;

One frequency generator, provides a first frequency and a second frequency;

One mode detector, the voltage detected on the input of described power supply changeover device and output produces one the 3rd signal to determine that described power supply changeover device operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode;

One sawtooth generator, provides one the 4th signal or one the 5th signal according to described 3rd signal and first frequency;

One first comparator, more described secondary signal and described 4th signal produce one the 6th signal;

One second comparator, more described secondary signal and described 5th signal produce one the 7th signal;

One control logic circuit, according to described 3rd, the 6th and the 7th signal and first and second FREQUENCY CONTROL first, second, third and the 4th switching of switch.

Aforesaid power supply changeover device, wherein said control logic circuit comprises:

One frequency eliminator, produces one the 3rd frequency to described first frequency frequency elimination;

One first logical circuit, produces one first control signal, the second control signal, the 3rd control signal and the 4th control signal according to described 6th signal, first frequency, second frequency, the 3rd frequency and one second reference voltage;

One first multiplexer, chooses one of them to control the switching of first and second switch described control signal from described first, second, third and the 4th according to described three signals;

One second logical circuit, produces one the 5th control signal, the 6th control signal, the 7th control signal and the 8th control signal according to described 7th signal, first frequency, the 3rd frequency and one the 3rd reference voltage;

One second multiplexer, chooses the switching that one of them controls the described 3rd and the 4th switch according to described 3rd signal from described 5th, the 6th, the 7th and the 8th control signal.

Aforesaid power supply changeover device, wherein said frequency eliminator comprises D type flip-flop.

Aforesaid power supply changeover device, wherein when described decompression mode, the switching cycle of first and second switch described is a period 1; Described in when described first buck-boost mode first, second, third and the 4th the switching cycle of switch be a second round being greater than the described period 1; Described in when described second buck-boost mode first, second, third and the 4th the switching cycle of switch be a period 3 being greater than the described period 1; The switching cycle of the 3rd and the 4th switch described in when described boost mode is a period 4 being less than second and third cycle described.

Aforesaid power supply changeover device, wherein when described first buck-boost mode, the responsibility cycle of the described 3rd and the 4th switch is fixed.

Aforesaid power supply changeover device, wherein when described second buck-boost mode, the responsibility cycle of first and second switch described is fixed.

A kind of control method of buck-boost power converter, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, between the first end that one second switch is connected to described inductance and an earth terminal, between the second end that one the 3rd switch is connected to described inductance and described earth terminal, and one diode there is an anode connect the output that the second end of described inductance and a negative electrode connect described power supply changeover device, it is characterized in that described control method comprises the following steps:

Second step: when first and second buck-boost mode described, the control of described first, second and third switch comprises:

A () closes described first switch, open described second switch, closes described 3rd switch;

B () opens described first switch, close described second switch, maintains described 3rd switch and closes;

C () maintains described first switch opens, maintain described second switch and close, open described 3rd switch.

Aforesaid control method, the step that the described power supply changeover device of wherein said decision operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode comprises:

When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than first critical value, determine that described power supply changeover device operates in decompression mode;

When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode;

When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode;

When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

Aforesaid control method, wherein more comprises:

The difference of amplifying between one first signal and a reference voltage produces a secondary signal, and described first signal is the function of voltage on described output;

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

More described secondary signal and the 4th signal produce one the 6th signal;

Described first, second and third switch is controlled according to the operator scheme of described power supply changeover device, the described 5th and the 6th signal, first frequency and second frequency.

Aforesaid control method, wherein when described decompression mode, the switching cycle of first and second switch described is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of the 3rd switch described in when described boost mode is a period 4 being less than second and third cycle described.

Aforesaid control method, wherein when described first buck-boost mode, the responsibility cycle of described 3rd switch is fixed.

A kind of buck-boost power converter, is characterized in that, comprising:

One inductance;

One diode, has an anode and connects the output that the second end of described inductance and a negative electrode connect described power supply changeover device;

Wherein, when first and second buck-boost mode described, the control of described first, second and third switch comprises (a) and closes described first switch, opens described second switch and close described 3rd switch, b () is opened described first switch, closes described second switch and is maintained described 3rd switch and close, and (c) maintains described first switch opens, maintain the closedown of described second switch and open described 3rd switch.

Aforesaid power supply changeover device, when the multiplier value at the described inductance two ends that the voltage of wherein said control circuit on described input and output and the load current on described output determine is less than first critical value, determine that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

One frequency generator, provides a first frequency and a second frequency;

One control logic circuit, the switching of first, second and third switch according to described 3rd, the 6th and the 7th signal and first and second FREQUENCY CONTROL.

One first logical circuit, produces one first control signal, the second control signal and the 3rd control signal and the 4th control signal according to described 6th signal, first frequency, second frequency, the 3rd frequency and one second reference voltage;

One second multiplexer, chooses the switching that one of them controls described 3rd switch according to described 3rd signal from described 5th, the 6th, the 7th and the 8th control signal.

Aforesaid power supply changeover device, wherein when described decompression mode, the switching cycle of first and second switch described is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of the 3rd switch described in when described boost mode is a period 4 being less than second and third cycle described.

Aforesaid power supply changeover device, wherein when described first buck-boost mode, the responsibility cycle of described 3rd switch is fixed.

A kind of control method of buck-boost power converter, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, one diode has an anode and connects the first end that an earth terminal and a negative electrode connect described inductance, between the second end that one second switch is connected to described inductance and described earth terminal, and one the 3rd switch be connected between the second end of described inductance and the output of described power supply changeover device, it is characterized in that described control method comprises the following steps:

A () closes described first switch, close described second switch, opens described 3rd switch;

B () opens described first switch, maintain described second switch and close, maintain described 3rd switch opens;

C () maintains described first switch opens, open described second switch, closes described 3rd switch.

When the multiplier value at the described inductance two ends determined with the load current on described output on described input and output is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode;

Aforesaid control method, wherein more comprises:

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

More described secondary signal and the 4th signal produce one the 6th signal;

Aforesaid control method, wherein when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of second and third switch described in when described boost mode is a period 4 being less than second and third cycle described.

Aforesaid control method, wherein when described first buck-boost mode, the responsibility cycle of second and third switch described is fixed.

Aforesaid control method, wherein when described second buck-boost mode, the responsibility cycle of described first switch is fixed.

A kind of buck-boost power converter, is characterized in that, comprising:

One inductance;

One diode, has an anode and connects the first end that an earth terminal and a negative electrode connect described inductance;

One second switch, between the second end being connected to described inductance and described earth terminal;

One the 3rd switch, is connected between the second end of described inductance and the output of described power supply changeover device;

One control circuit, control the switching of described first, second and third switch, and determine that described power supply changeover device operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode according to the load current on the voltage on described input and output and described output;

Wherein, when first and second buck-boost mode described, the control of described first, second and third switch comprises (a) and closes described first switch, closes described second switch and open described 3rd switch, b () is opened described first switch, is maintained the closedown of described second switch and maintain described 3rd switch opens, and (c) maintains described first switch opens, opens described second switch and close described 3rd switch.

Aforesaid power supply changeover device, when the multiplier value at the described inductance two ends that the voltage of wherein said control circuit on described input and output and the load current on described output determine is less than first critical value, determine that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than one first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

One frequency generator, provides a first frequency and a second frequency;

One first multiplexer, chooses switching that one of them control described first switch from described first, second, third and the 4th control signal according to described three signals;

One second multiplexer, chooses one of them to control the switching of second and third switch described from described 5th, the 6th, the 7th and the 8th control signal according to described 3rd signal.

Aforesaid power supply changeover device, wherein when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of second and third switch described in when described boost mode is a period 4 being less than second and third cycle described.

Aforesaid power supply changeover device, wherein when described first buck-boost mode, the responsibility cycle of second and third switch described is fixed.

42, power supply changeover device as claimed in claim 35, it is characterized in that, when described second buck-boost mode, the responsibility cycle of described first switch is fixed.

A kind of control method of buck-boost power converter, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, one first diode has an anode and connects the first end that an earth terminal and a negative electrode connect described inductance, between the second end that one second switch is connected to described inductance and described earth terminal, and one second diode there is an anode connect the output that the second end of described inductance and a negative electrode connect described power supply changeover device, it is characterized in that described control method comprises the following steps:

Second step: when first and second buck-boost mode described, the control of first and second switch described comprises:

A () closes described first switch, close described second switch;

B () opens described first switch, maintain described second switch and close;

C () maintains described first switch opens, open described second switch.

When the multiplier value at the described inductance two ends that the voltage on described input and output and load current determine is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

Aforesaid control method, wherein more comprises:

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

More described secondary signal and the 4th signal produce one the 6th signal;

First and second switch described is controlled according to the operator scheme of described power supply changeover device, the described 5th and the 6th signal, first frequency and second frequency.

Aforesaid control method, wherein when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first and second switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first and second switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; When described boost mode, the switching cycle of described second switch is a period 4 being less than second and third cycle described.

Aforesaid control method, wherein when described first buck-boost mode, the responsibility cycle of described second switch is fixed.

A kind of buck-boost power converter, is characterized in that, comprising:

One inductance;

One first diode, has an anode and connects the first end that an earth terminal and a negative electrode connect described inductance;

One second diode, has an anode and connects the output that the second end of described inductance and a negative electrode connect described power supply changeover device;

One control circuit, control the switching of first and second switch described, and determine that described power supply changeover device operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode according to the load current on the voltage on described input and output and described output;

Wherein, when first and second buck-boost mode described, the control of first and second switch described comprises (a) and closes described first switch and close described second switch, b () is opened described first switch and is maintained described second switch and close, and (c) maintains described first switch opens and open described second switch.

Aforesaid power supply changeover device, wherein said control circuit, when the multiplier value at the described inductance two ends determined when the load current on the voltage on described input and output and described output is less than first critical value, determines that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

One frequency generator, provides a first frequency and a second frequency;

One control logic circuit, the switching of first and second switch according to described 3rd, the 6th and the 7th signal and first and second FREQUENCY CONTROL.

One second multiplexer, chooses the switching that one of them controls described second switch according to described 3rd signal from described 5th, the 6th, the 7th and the 8th control signal.

Aforesaid power supply changeover device, wherein when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first and second switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first and second switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; When described boost mode, the switching cycle of described second switch is a period 4 being less than second and third cycle described.

Aforesaid power supply changeover device, wherein when described first buck-boost mode, the responsibility cycle of described second switch is fixed.

Aforesaid power supply changeover device, wherein when described second buck-boost mode, the responsibility cycle of described first switch is fixed.

After adopting technique scheme, buck-boost power converter of the present invention and control method thereof have the following advantages:

1. when power supply changeover device operates in buck-boost mode, at least two switches described in controlling with new transfer sequence, and then reduce switch cost and conduction losses.

2. when power supply changeover device enters buck-boost mode by decompression mode or boost mode, the switching cycle of described at least two switches is extended, to reduce switch cost further, and consider that the impact of load current on buck responsibility cycle makes it correctly can put switch mode, therefore output voltage can not be influenced because of for a change pattern.

Accompanying drawing explanation

Fig. 1 is known buck-boost power converter schematic diagram;

Fig. 2 is first embodiment of the present invention schematic diagram;

Fig. 3 is signal waveform when power supply changeover device operates in first mode in Fig. 2;

Fig. 4 is inductive current IL and switching sequence in inductance L when power supply changeover device operates in first mode in Fig. 2;

Fig. 5 is signal waveform when power supply changeover device operates in the second pattern in Fig. 2;

Fig. 6 is inductive current IL and switching sequence in inductance L when power supply changeover device operates in the second pattern in Fig. 2;

Fig. 7 is signal waveform when power supply changeover device operates in three-mode in Fig. 2;

Fig. 8 is inductive current IL and switching sequence in inductance L when power supply changeover device operates in three-mode in Fig. 2;

Fig. 9 is signal waveform when power supply changeover device operates in four-mode in Fig. 2;

Figure 10 is inductive current IL and switching sequence in inductance L when power supply changeover device operates in four-mode in Fig. 2;

Figure 11 is the mode transition diagram of power supply changeover device in Fig. 2;

Figure 12 is the embodiment schematic diagram of control logic circuit in Fig. 2;

Figure 13 is second embodiment of the present invention schematic diagram;

Figure 14 is third embodiment of the present invention schematic diagram;

Figure 15 is fourth embodiment of the present invention schematic diagram;

Figure 16 is the embodiment schematic diagram of mode detector.

In figure, 10, power supply changeover device 12, power stage 14, control circuit 16, control logic circuit 18, comparator 20, comparator 22, sawtooth generator 24, error amplifier 30, power supply changeover device 32, power stage 34, control circuit 36, control logic circuit 3602, D type flip-flop 3604, logical circuit 3606, multiplexer 3608, logical circuit 3610, multiplexer 38, mode detector 3802, current source 3804, operational amplifier 3806, current source 3808, comparator 3810, comparator 3812, comparator 40, comparator 42, comparator 44, sawtooth generator 46, error amplifier 48, frequency generator 50, the waveform 52 of sawtooth signal SAW12, the waveform 54 of error signal VEA, the waveform 56 of signal PWM1, the waveform 58 of frequency Clk_buck, the waveform 60 of frequency Clk_boost, the waveform 62 of control signal VA, the waveform 64 of control signal VB, the waveform 66 of control signal VC, the waveform 68 of control signal VD, the waveform 70 of sawtooth signal SAW12, the waveform 72 of error signal VEA, the waveform 74 of signal PWM1, the waveform 76 of frequency Clk_buck, the waveform 78 of frequency Clk_boost, the waveform 80 of control signal VA, the waveform 82 of control signal VB, the waveform 84 of control signal VC, the waveform 86 of control signal VD, the waveform 88 of sawtooth signal SAW34, the waveform 90 of error signal VEA, the waveform 92 of signal PWM2, the waveform 94 of frequency Clk_buck, the waveform 96 of frequency Clk_boost, the waveform 98 of control signal VA, the waveform 100 of control signal VB, the waveform 102 of control signal VC, the waveform 104 of control signal VD, the waveform 106 of sawtooth signal SAW34, the waveform 108 of error signal VEA, the waveform 110 of signal PWM2, the waveform 112 of frequency Clk_buck, the waveform 114 of frequency Clk_boost, the waveform 116 of control signal VA, the waveform 118 of control signal VB, the waveform 120 of control signal VC, the waveform 130 of control signal VD, power supply changeover device 132, power stage 140, power supply changeover device 142, power stage 150, power supply changeover device 152, power stage.

Embodiment

Below in conjunction with embodiment and accompanying drawing thereof, the present invention is illustrated further.

Now refer to Fig. 2, Fig. 2 shows the first embodiment of the present invention.As shown in the figure, described in buck-boost power converter 30, control circuit 34 exports control signal VA, VB, VC and VD driving power level 32, and so that input voltage vin is converted to output voltage Vout, resistance R1 and R2 pressure-dividing output voltage Vout produces feedback signal VFB to control circuit 34.In power stage 32, interrupteur SW 1 is connected between input voltage vin and inductance L, and interrupteur SW 2 is connected between inductance L and earth terminal GND, and interrupteur SW 3 is connected between inductance L and earth terminal GND, and interrupteur SW 4 is connected between inductance L and output voltage Vout.Because the responsibility cycle of whole system is not only relevant with input voltage and output voltage, load current also can affect the size of responsibility cycle, and therefore the factor of load current also must be taken into account by the switching point of pattern.In control circuit 34, mode detector 38 detects input voltage vin, output voltage Vout and load current Iload produces mode select signal S [3:0] to determine the operator scheme of power supply changeover device 30, error amplifier 46 produces error signal VEA according to reference voltage Vref and feedback signal VFB, frequency generator 48 provides frequency Clk_boost and Clk_buck, frequency Clk_boost and Clk_buck has fixing cycle T s and fixing responsibility cycle, sawtooth generator 44 provides sawtooth signal SAW12 and SAW34 according to frequency Clk_boost and mode select signal S [3:0], comparator 40 comparison error signal VEA and sawtooth signal SAW12 produces signal PWM1, comparator 42 comparison error signal VEA and sawtooth signal SAW34 produces signal PWM2, control logic circuit 36 is according to signal PWM1 and PWM2, mode select signal S [3:0] and frequency Clk_boost and Clk_buck produces control signal VA, VB, VC and VD diverter switch SW1, SW2, SW3 and SW4 is to be converted to output voltage Vout by input voltage vin.

Described power supply changeover device 30 may operate in four kinds of patterns, and when the multiplier value at the inductance two ends that input voltage vin, output voltage Vout and load current Iload determine is less than the first critical value, power supply changeover device 30 operates in first mode.Fig. 3 display power supply transducer 30 operates in signal waveform during first mode, wherein waveform 50 is sawtooth signal SAW12, waveform 52 is error signal VEA, waveform 54 is signal PWM1, and waveform 56 is frequency Clk_buck, and waveform 58 is frequency Clk_boost, waveform 60 is control signal VA, waveform 62 is control signal VB, and waveform 64 is control signal VC, and waveform 66 is control signal VD.Inductive current IL and switching sequence in inductance L when Fig. 4 display power supply transducer 30 operates in first mode.First mode is simple decompression mode, at time t1 to t2, control signal VA, VB, VC and VD are low level, as shown in waveform 60,62,64 and 66, because interrupteur SW 1 and SW4 are PMOS, interrupteur SW 2 and SW3 are NMOS, therefore interrupteur SW 1 and SW4 open (turn on) and interrupteur SW 2 and SW3 closes (turn off), be defined as tAD1 during this period of time, in time tAD1, input voltage vin makes inductive current IL rise to inductance L charging, as shown in Figure 4.Be high levle and control signal VC and VD is low level at time t2 to t3, control signal VA and VB, therefore interrupteur SW 2 and SW4 open and interrupteur SW 1 and SW3 close, this time is defined as tBD1, and in time tBD1, inductance L electric discharge makes inductive current IL decline.In a first mode, the switching cycle of interrupteur SW 1 and SW2 and the cycle of inductive current IL are Ts, and step-down responsibility cycle is the responsibility cycle ratio of interrupteur SW 1 than Kbuck1.

When the multiplier value at the inductance two ends that input voltage vin, output voltage Vout and load current Iload determine is greater than the first critical value and is less than 1, power supply changeover device 30 operates in the second pattern.Fig. 5 display power supply transducer 30 operates in signal waveform during the second pattern, wherein waveform 68 is sawtooth signal SAW12, waveform 70 is error signal VEA, waveform 72 is signal PWM1, and waveform 74 is frequency Clk_buck, and waveform 76 is frequency Clk_boost, waveform 78 is control signal VA, waveform 80 is control signal VB, and waveform 82 is control signal VC, and waveform 84 is control signal VD.Inductive current IL and switching sequence when Fig. 6 display power supply transducer 30 operates in the second pattern.Second pattern is buck-boost mode, at time t4 to t5, control signal VA and VB is high levle and control signal VC and VD is low level, therefore interrupteur SW 1 and SW3 close and interrupteur SW 2 and SW4 open, be defined as tBD2 during this period of time, at time t5 to t6, control signal VA, VB, VC and VD is low level, therefore interrupteur SW 1 and SW4 open and interrupteur SW 2 and SW3 closedown, be defined as tAD2 during this period of time, at time t6 to t7, control signal A and B is low level and control signal C and D is high levle, therefore interrupteur SW 1 and SW3 open and interrupteur SW 2 and SW4 closedown, be defined as tAC1 during this period of time.In a second mode, the switching cycle of interrupteur SW 1, SW2, SW3 and SW4 and the cycle of inductive current IL are 2Ts.With reference to Fig. 6, each cycle of inductive current IL comprises step-down and boost operations, in a second mode, the responsibility cycle of interrupteur SW 3 and SW4 is determined by frequency Clk_boost, therefore interrupteur SW 3 and SW4 have fixing responsibility cycle, therefore, the boosting responsibility cycle during boost operations is fixed than Kboost1, output voltage Vout can be allowed by the step-down responsibility cycle of adjustment during reduced pressure operation to stablize than Kbuck2.

When the multiplier value at the inductance two ends that input voltage vin, output voltage Vout and load current Iload determine is less than the second critical value and is greater than 1, power supply changeover device 30 operates in three-mode.Fig. 7 display power supply transducer 30 operates in signal waveform during three-mode, wherein waveform 86 is sawtooth signal SAW34, waveform 88 is error signal VEA, waveform 90 is signal PWM2, and waveform 92 is frequency Clk_buck, and waveform 94 is frequency Clk_boost, waveform 96 is control signal VA, waveform 98 is control signal VB, and waveform 100 is control signal VC, and waveform 102 is control signal VD.Inductive current IL and switching sequence when Fig. 8 display power supply transducer 30 operates in three-mode.Three-mode is buck-boost mode, at time t8 to t9, control signal VA and VB is high levle and control signal VC and VD is low level, therefore interrupteur SW 1 and SW3 close and interrupteur SW 2 and SW4 open, be defined as tBD3 during this period of time, at time t9 to t10, control signal VA, VB, VC and VD is low level, therefore interrupteur SW 1 and SW4 open and interrupteur SW 2 and SW3 closedown, be defined as tAD3 during this period of time, at time t10 to t11, control signal A and B is low level and control signal C and D is high levle, therefore interrupteur SW 1 and SW3 open and interrupteur SW 2 and SW4 closedown, be defined as tAC2 during this period of time.In three-mode, the switching cycle of interrupteur SW 1, SW2, SW3 and SW4 and the cycle of inductive current IL are 2Ts.With reference to Fig. 8, each cycle of inductive current IL comprises step-down and boost operations, in three-mode, the responsibility cycle of interrupteur SW 1 and SW2 is determined by frequency Clk_buck, therefore the responsibility cycle of interrupteur SW 1 and SW2 is fixed, therefore, the step-down responsibility cycle during reduced pressure operation is fixed than Kbuck3, output voltage Vout can be allowed by the boosting responsibility cycle of adjustment during boost operations to stablize than Kboost2.

Multiplier value when the inductance two ends that input voltage vin, output voltage Vou and load current Iload determine is greater than the second critical value, and power supply changeover device 30 operates in four-mode.The signal waveform of Fig. 9 display power supply transducer 30 operating item when four-mode, wherein waveform 104 is sawtooth signal SAW34, waveform 106 is error signal VEA, waveform 108 is signal PWM2, and waveform 110 is frequency Clk_buck, and waveform 112 is frequency Clk_boost, waveform 114 is control signal VA, waveform 116 is control signal VB, and waveform 118 is control signal VC, and waveform 120 is control signal VD.Inductive current IL and switching sequence when Figure 10 display power supply transducer 30 operates in four-mode.Four-mode is simple boost mode, at time t12 to t13, control signal VA and VB is low level and control signal VC and VD is high levle, therefore interrupteur SW 1 and SW3 open and interrupteur SW 2 and SW4 closedown, be defined as tAC3 during this period of time, be low level at time t13 to t14, control signal VA, VB, VC and VD, therefore interrupteur SW 1 and SW4 open and interrupteur SW 2 and SW3 closedown, are defined as tAD4 during this period of time.In four-mode, the switching cycle of interrupteur SW 3 and SW4 and the cycle of inductive current IL are Ts, and boosting responsibility cycle is the responsibility cycle ratio of interrupteur SW 3 than Kboost3.

When power supply changeover device 30 operates in buck-boost mode, the transfer sequence of switch opens interrupteur SW 2 and SW4 and closing switch SW1 and SW3 for (1), (2) interrupteur SW 1 and SW4 is opened and closing switch SW2 and SW3, (3) interrupteur SW 1 and SW3 is opened and closing switch SW2 and SW4, compared with known techniques, in the circulation of same time, the switching over number of times of power supply changeover device 30 is less, and when the operator scheme of power supply changeover device 30 enters buck-boost mode by decompression mode or boost mode, the switching cycle of switch will be extended for 2Ts by Ts, therefore can switch cost be reduced.Moreover, the duration extension that this new switching sequence can allow inductance L be connected with the output end vo ut of power supply changeover device 30, therefore can conduction losses be reduced.

Utilize voltage-second balance (voltage second balance) principle can derive the input voltage vin of power supply changeover device 30 under four kinds of patterns, the relation between output voltage Vout and load current Iload.With reference to Fig. 4, suppose that the cross-pressure on each interrupteur SW 1, SW2, SW3 and SW4 is all Vsw, when converters operation is at first mode, the pass between the cross-pressure Vsw of input voltage vin, output voltage Vout and switch is

Vin-2Vsw/ (tAD1/Ts)=Vout/ (tAD1/Ts) formula 1

With reference to Fig. 6, when the second pattern, the pass between the cross-pressure Vsw of input voltage vin, output voltage Vout and switch is

Vin-4Vsw/(Ts+tAD2_1)

＝Vout[(Ts+tAD2_2)/(Ts+tAD2_1)]

=Vout [(2-Kboost1) Ts/ (Ts+tAD2_1)] formula 2

With reference to Fig. 8, when three-mode, the pass between the cross-pressure Vsw of input voltage vin, output voltage Vout and switch is

Vin-4Vsw/(Ts+tAD3_1)

＝Vout[(Ts+tAD3_2)/(Ts+tAD3_1)]

=Vout [(Ts+tAD3_2)/(1+Kbuck3) Ts] formula 3

With reference to Figure 10, when four-mode, the pass between the cross-pressure Vsw of input voltage vin, output voltage Vout and switch is

Vin-2Vsw=Vout (1-tAC3/Ts) formula 4

In order to prevent the nonlinear problem of sawtooth signal SAW12 and SAW34, output voltage Vout cannot be stablized, therefore the restriction maximum liability cycle of step-down and the minimum responsibility cycle of boosting are respectively K1 and K2, with make input voltage vin close to or equal output voltage Vout time, can allow output voltage Vout stablize.The mode transition diagram of Figure 11 display power supply transducer 30, can obtain the patten transformation of power supply changeover device 30 from formula 1 to formula 4 and set critical value K1 and K2.When power supply changeover device 30 operates in first mode, with reference to Figure 11, if when input voltage vin continuous decrease makes the multiplier value at inductance L two ends equal critical value A1, power supply changeover device 30 switches to the second pattern.When power supply changeover device 30 operates in the second pattern, with reference to Figure 11, if when input voltage vin continuous decrease makes the multiplier value at inductance L two ends equal critical value A2, power supply changeover device 30 switches to three-mode.When power supply changeover device 30 operates in three-mode, with reference to Figure 11, if when input voltage vin continuous decrease makes the multiplier value at inductance L two ends equal critical value A3, power supply changeover device 30 switches to four-mode.When power supply changeover device 30 operates in four-mode, with reference to Figure 11 and formula 4, if input voltage vin continues to rise when making the multiplier value at inductance L two ends equal critical value A3, power supply changeover device 30 switches to three-mode.When power supply changeover device 30 operates in three-mode, if input voltage vin continues to rise when making the multiplier value at inductance L two ends equal critical value A2, power supply changeover device 30 switches to the second pattern.When power supply changeover device 30 operates in the second pattern, if input voltage vin continues to rise, when making the multiplier value of inductance two ends L equal critical value A1, power supply changeover device 30 switches to first mode.

Figure 12 shows the embodiment of control logic circuit 36 in Fig. 2, wherein D type flip-flop 3602 as frequency eliminator in order to frequency Clk_boost frequency elimination produce frequency CLK2 and CLK2B, logical circuit 3604 is according to signal PWM1, frequency Clk_boost, the current potential of CLK2 and Clk_buck and earth terminal GND produces control signal S1, S2, S3 and S4, multiplexer 3606 according to mode select signal S [3:0] from control signal S4, S3, one of them is chosen as control signal VA and VB in S2 and S1, logical circuit 3608 is according to the current potential of earth terminal GND, frequency CLK2B and Clk_boost and signal PWM2 produces control signal S5, S6, S7 and S8, multiplexer 3610 according to mode select signal S [3:0] from control signal S8, S7, one of them is chosen as control signal VC and VD in S6 and S5.

Figure 13 shows the second embodiment of the present invention, in buck-boost power converter 130, control circuit 34 driving power level 132 is to be converted to output voltage Vout by input voltage vin, and resistance R1 and R2 pressure-dividing output voltage Vout produces feedback signal VFB to control circuit 34.In power stage 132, interrupteur SW 1 is connected between input voltage vin and inductance L, and interrupteur SW 2 is connected between inductance L and earth terminal GND, and interrupteur SW 3 is connected between inductance L and earth terminal GND, and diode D1 is connected between inductance L and output voltage Vout.Control circuit 34 comprises control logic circuit 36, mode detector 38, comparator 40 and 42, sawtooth generator 44, error amplifier 46 and frequency generator 48 equally, and control logic circuit 36 produces control signal VA, VB and VC diverter switch SW1, SW2 and SW3 so that input voltage vin is converted to output voltage Vout according to signal PWM1 and PWM2, mode select signal S [3:0] and frequency Clk_boost and Clk_buck.

When power supply changeover device 130 operates in buck-boost mode, the transfer sequence of its switch opens interrupteur SW 2 and closing switch SW1 and SW3 for (1), (2) interrupteur SW 1 is opened and closing switch SW2 and SW3, (3) interrupteur SW 1 and SW3 is opened and closing switch SW2, repeat step (1) afterwards to (3), wherein, work as input voltage vin, the responsibility cycle that output voltage Vout and load current Iload determines is greater than the first critical value and is less than 1, the responsibility cycle of interrupteur SW 3 is fixed, work as input voltage vin, the responsibility cycle that output voltage Vout and load current Iload determines is less than the second critical value and is greater than 1, the responsibility cycle of interrupteur SW 1 and SW2 is fixed, and when the operator scheme of power supply changeover device 130 enters buck-boost mode by decompression mode or boost mode, the switching cycle of switch will be extended for 2Ts by Ts.

Figure 14 shows the third embodiment of the present invention, in buck-boost power converter 140, control circuit 34 driving power level 142 is to be converted to output voltage Vout by input voltage vin, and resistance R1 and R2 pressure-dividing output voltage Vout produces feedback signal VFB to control circuit 34.In power stage 142, interrupteur SW 1 is connected between input voltage vin and inductance L, and diode D2 is connected between inductance L and earth terminal GND, and interrupteur SW 3 is connected between inductance L and earth terminal GND, and interrupteur SW 4 is connected between inductance L and output voltage Vout.Control circuit 34 is isotype comprises control logic circuit 36, mode detector 38, comparator 40 and 42, sawtooth generator 44, error amplifier 46 and frequency generator 48, and control logic circuit 36 produces control signal VA, VC and VD diverter switch SW1, SW3 and SW4 so that input voltage vin is converted to output voltage Vout according to signal PWM1 and PWM2, mode select signal S [3:0] and frequency Clk_boost and Clk_buck.

When power supply changeover device 140 operates in buck-boost mode, the transfer sequence of its switch opens interrupteur SW 4 and closing switch SW1 and SW3 for (1), (2) interrupteur SW 1 and SW4 is opened and closing switch SW3, (3) interrupteur SW 1 and SW3 is opened and closing switch SW4, repeat step (1) afterwards to (3), wherein, work as input voltage vin, the responsibility cycle that output voltage Vout and load current Iload determines is greater than the first critical value and is less than 1, the responsibility cycle of interrupteur SW 3 and SW4 is fixed, work as input voltage vin, the responsibility cycle that output voltage Vout and load current Iload determines is less than the second critical value and is greater than 1, the responsibility cycle of interrupteur SW 1 is fixed, and when the operator scheme of power supply changeover device 140 enters buck-boost mode by decompression mode or boost mode, the switching cycle of switch will be extended for 2Ts by Ts.

Figure 15 shows the fourth embodiment of the present invention, in buck-boost power converter 150, control circuit 34 driving power level 152 is to be converted to output voltage Vout by input voltage vin, and resistance R1 and R2 pressure-dividing output voltage Vout produces feedback signal VFB to control circuit 34.In power stage 152, interrupteur SW 1 is connected between input voltage vin and inductance L, and diode D3 is connected between inductance L and earth terminal GND, and interrupteur SW 3 is connected between inductance L and earth terminal GND, and diode D4 is connected between inductance L and output voltage Vout.Control circuit 34 is isotype comprises control logic circuit 36, mode detector 38, comparator 40 and 42, sawtooth generator 44, error amplifier 46 and frequency generator 48, and control logic circuit 36 produces control signal VA and VC diverter switch SW1 and SW3 so that input voltage vin is converted to output voltage Vout according to signal PWM1 and PWM2, mode select signal S [3:0] and frequency Clk_boost and Clk_buck.

When power supply changeover device 150 operates in buck-boost mode, the transfer sequence of its switch is (1) closing switch SW1 and SW3, (2) interrupteur SW 1 is opened and closing switch SW3, (3) interrupteur SW 1 and SW3 is opened, repeat step (1) afterwards to (3), wherein, work as input voltage vin, the responsibility cycle that output voltage Vout and load current Iload determines is greater than the first critical value and is less than 1, the responsibility cycle of interrupteur SW 3 is fixed, work as input voltage vin, the responsibility cycle that output voltage Vout and load current Iload determines is less than the second critical value and is greater than 1, the responsibility cycle of interrupteur SW 1 is fixed, and when the operator scheme of power supply changeover device 150 enters buck-boost mode by decompression mode or boost mode, the switching cycle of switch will be extended for 2Ts by Ts.

The embodiment of Figure 16 display mode detector 38, in mode detector 38, when interrupteur SW 1 is opened, switch MP1 also opens simultaneously, therefore voltage Vb is (Vin-Vsw-Ib × R3), wherein voltage Vsw is directly proportional to load current Iload, voltage Vb and Va is locked in same level by operational amplifier 3804, therefore the electric current I a of resistance R4 is flow through for (Ib+Vsw/R4), design current source 3802 and 3806 is equal, make to flow through the electric current I c of resistance R5 for (Vsw/R4), therefore can be derived from voltage

VDEC＝Vin-Ia×R4-Ic×R5

＝Vin-Ib×R4-Vsw-(R5/R4)×Vsw

=Vin-(1+R5/R4) Vsw-Ib × R4 formula 5

Due to (Ib × R4) can design relatively little, therefore voltage

formula 6

From formula 6, ratio by adjusting resistance R5 and R4 can regulation voltage VDEC, then comparator 3808,3810 and 3812 compares (M1 × Vout), (M2 × Vout) and (M3 × Vout) and voltage VDEC respectively, and logical circuit 3814 produces mode select signal S [3:0] according to the output of comparator 3808,3810 and 3812.

Above embodiment is used for illustrative purposes only, but not limitation of the present invention, person skilled in the relevant technique, without departing from the spirit and scope of the present invention, can also make various conversion or change.Therefore, all equivalent technical schemes also should belong to category of the present invention, should be limited by each claim.

Claims

1. the control method of a buck-boost power converter, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, between the first end that one second switch is connected to described inductance and an earth terminal, between the second end that one the 3rd switch is connected to described inductance and described earth terminal, and one the 4th switch be connected between the second end of described inductance and the output of described power supply changeover device, it is characterized in that described control method comprises the following steps:

Detect the voltage on described input and output and the load current on described output to determine that described power supply changeover device operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode;

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

More described secondary signal and the 4th signal produce one the 6th signal; And

Described first, second, third and the 4th switch is controlled according to the operator scheme of described power supply changeover device, the described 5th and the 6th signal, first frequency and second frequency;

When first and second buck-boost mode described, described first, second, third and the 4th the control of switch comprise:

A, close described first switch, open described second switch, close described 3rd switch, open described 4th switch;

B, open described first switch, close described second switch, maintain described 3rd switch and close, maintain described 4th switch opens; And

C, maintain described first switch opens, maintain described second switch and close, open described 3rd switch, close described 4th switch.

2. control method as claimed in claim 1, it is characterized in that, the step that the described power supply changeover device of described decision operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode comprises the following steps:

Third step: the multiplier value when the described inductance two ends that the voltage on described input and output and load current determine is less than one the 3rd critical value and is greater than described second critical value, determines that described power supply changeover device operates in described second buck-boost mode; And

3. control method as claimed in claim 1, it is characterized in that, when described decompression mode, the switching cycle of first and second switch described is a period 1; Described in when described first buck-boost mode first, second, third and the 4th the switching cycle of switch be a second round being greater than the described period 1; Described in when described second buck-boost mode first, second, third and the 4th the switching cycle of switch be a period 3 being greater than the described period 1; The switching cycle of the 3rd and the 4th switch described in when described boost mode is a period 4 being less than second and third cycle described.

4. control method as claimed in claim 1, it is characterized in that, when described first buck-boost mode, the responsibility cycle of the described 3rd and the 4th switch is fixed.

5. control method as claimed in claim 1, it is characterized in that, when described second buck-boost mode, the responsibility cycle of first and second switch described is fixed.

6. a buck-boost power converter, is characterized in that, comprising:

One inductance;

One the 4th switch, is connected between the second end of described inductance and the output of described power supply changeover device; And

Wherein, described control circuit comprises:

One frequency generator, provides a first frequency and a second frequency;

One second comparator, more described secondary signal and described 5th signal produce one the 7th signal; And

One control logic circuit, according to described 3rd, the 6th and the 7th signal and first and second FREQUENCY CONTROL first, second, third and the 4th switching of switch;

Wherein, when first and second buck-boost mode described, described first, second, third and the 4th the control of switch comprise a, close described first switch, open described second switch, close described 3rd switch and open described 4th switch, b, open described first switch, close described second switch, maintain described 3rd switch close and maintain described 4th switch opens, and c, described first switch opens of maintenance, maintain described second switch close, open described 3rd switch and close described 4th switch.

7. power supply changeover device as claimed in claim 6, it is characterized in that, when the multiplier value at the described inductance two ends that the voltage of described control circuit on described input and output and described load current determine is less than first critical value, determine that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the voltage on described input and output and described load current determine is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the voltage on described input and output and described load current determine is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the voltage on described input and output and load current determine is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

8. power supply changeover device as claimed in claim 6, it is characterized in that, described control logic circuit comprises:

One second logical circuit, produces one the 5th control signal, the 6th control signal, the 7th control signal and the 8th control signal according to described 7th signal, first frequency, the 3rd frequency and one the 3rd reference voltage; And

9. power supply changeover device as claimed in claim 8, it is characterized in that, described frequency eliminator comprises D type flip-flop.

10. power supply changeover device as claimed in claim 6, it is characterized in that, when described decompression mode, the switching cycle of first and second switch described is a period 1; Described in when described first buck-boost mode first, second, third and the 4th the switching cycle of switch be a second round being greater than the described period 1; Described in when described second buck-boost mode first, second, third and the 4th the switching cycle of switch be a period 3 being greater than the described period 1; The switching cycle of the 3rd and the 4th switch described in when described boost mode is a period 4 being less than second and third cycle described.

11. power supply changeover devices as claimed in claim 6, is characterized in that, when described first buck-boost mode, the responsibility cycle of the described 3rd and the 4th switch is fixed.

12. power supply changeover devices as claimed in claim 6, it is characterized in that, when described second buck-boost mode, the responsibility cycle of first and second switch described is fixed.

The control method of 13. 1 kinds of buck-boost power converters, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, between the first end that one second switch is connected to described inductance and an earth terminal, between the second end that one the 3rd switch is connected to described inductance and described earth terminal, and one diode there is an anode connect the output that the second end of described inductance and a negative electrode connect described power supply changeover device, it is characterized in that described control method comprises the following steps:

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

Described first, second and third switch is controlled according to the operator scheme of described power supply changeover device, the described 5th and the 6th signal, first frequency and second frequency;

When first and second buck-boost mode described, the control of described first, second and third switch comprises:

A, close described first switch, open described second switch, close described 3rd switch;

B, open described first switch, close described second switch, maintain described 3rd switch and close; And

C, maintain described first switch opens, maintain described second switch and close, open described 3rd switch.

14. control methods as claimed in claim 13, it is characterized in that, the step that the described power supply changeover device of described decision operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode comprises:

When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; And

15. control methods as claimed in claim 13, is characterized in that, when described decompression mode, the switching cycle of first and second switch described is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of the 3rd switch described in when described boost mode is a period 4 being less than second and third cycle described.

16. control methods as claimed in claim 13, is characterized in that, when described first buck-boost mode, the responsibility cycle of described 3rd switch is fixed.

17. control methods as claimed in claim 13, it is characterized in that, when described second buck-boost mode, the responsibility cycle of first and second switch described is fixed.

18. 1 kinds of buck-boost power converters, is characterized in that, comprising:

One inductance;

One diode, has an anode and connects the output that the second end of described inductance and a negative electrode connect described power supply changeover device; And

Wherein, described control circuit comprises:

One frequency generator, provides a first frequency and a second frequency;

One control logic circuit, the switching of first, second and third switch according to described 3rd, the 6th and the 7th signal and first and second FREQUENCY CONTROL;

Wherein, when first and second buck-boost mode described, the control of described first, second and third switch comprises a, closes described first switch, opens described second switch and closes described 3rd switch, b, open described first switch, close described second switch and maintain described 3rd switch close, and c, described first switch opens of maintenance, maintain described second switch close and open described 3rd switch.

19. power supply changeover devices as claimed in claim 18, it is characterized in that, when the multiplier value at the described inductance two ends that the voltage of control circuit on described input and output and the load current on described output determine is less than first critical value, determine that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

20. power supply changeover devices as claimed in claim 18, it is characterized in that, described control logic circuit comprises:

One second logical circuit, produces one the 5th control signal, the 6th control signal, the 7th control signal and the 8th control signal according to described 7th signal, first frequency, the 3rd frequency and one the 3rd reference voltage; And one second multiplexer, from described 5th, the 6th, the 7th and the 8th control signal, choose the switching that one of them controls described 3rd switch according to described 3rd signal.

21. power supply changeover devices as claimed in claim 20, it is characterized in that, described frequency eliminator comprises D type flip-flop.

22. power supply changeover devices as claimed in claim 18, is characterized in that, when described decompression mode, the switching cycle of first and second switch described is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of the 3rd switch described in when described boost mode is a period 4 being less than second and third cycle described.

23. power supply changeover devices as claimed in claim 18, is characterized in that, when described first buck-boost mode, the responsibility cycle of described 3rd switch is fixed.

24. power supply changeover devices as claimed in claim 18, it is characterized in that, when described second buck-boost mode, the responsibility cycle of first and second switch described is fixed.

The control method of 25. 1 kinds of buck-boost power converters, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, one diode has an anode and connects the first end that an earth terminal and a negative electrode connect described inductance, between the second end that one second switch is connected to described inductance and described earth terminal, and one the 3rd switch be connected between the second end of described inductance and the output of described power supply changeover device, it is characterized in that described control method comprises the following steps:

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

A, close described first switch, close described second switch, open described 3rd switch;

B, open described first switch, maintain described second switch and close, maintain described 3rd switch opens; And

C, maintain described first switch opens, open described second switch, close described 3rd switch.

26. control methods as claimed in claim 25, it is characterized in that, the step that the described power supply changeover device of described decision operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode comprises:

27. control methods as claimed in claim 25, is characterized in that, when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of second and third switch described in when described boost mode is a period 4 being less than second and third cycle described.

28. control methods as claimed in claim 25, it is characterized in that, when described first buck-boost mode, the responsibility cycle of second and third switch described is fixed.

29. control methods as claimed in claim 25, is characterized in that, when described second buck-boost mode, the responsibility cycle of described first switch is fixed.

30. 1 kinds of buck-boost power converters, is characterized in that, comprising:

One inductance;

One the 3rd switch, is connected between the second end of described inductance and the output of described power supply changeover device; And

Wherein, described control circuit comprises:

One frequency generator, provides a first frequency and a second frequency;

Wherein, when first and second buck-boost mode described, the control of described first, second and third switch comprises a, closes described first switch, closes described second switch and opens described 3rd switch, b, open described first switch, maintain described second switch and close and maintain described 3rd switch opens, and c, described first switch opens of maintenance, open described second switch and close described 3rd switch.

31. power supply changeover devices as claimed in claim 30, its feature exists, when the multiplier value at the described inductance two ends that the voltage of described control circuit on described input and output and the load current on described output determine is less than first critical value, determine that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than one first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

32. power supply changeover devices as claimed in claim 30, it is characterized in that, described control logic circuit comprises:

33. power supply changeover devices as claimed in claim 32, it is characterized in that, described frequency eliminator comprises D type flip-flop.

34. power supply changeover devices as claimed in claim 30, is characterized in that, when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first, second and third switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first, second and third switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; The switching cycle of second and third switch described in when described boost mode is a period 4 being less than second and third cycle described.

35. power supply changeover devices as claimed in claim 30, it is characterized in that, when described first buck-boost mode, the responsibility cycle of second and third switch described is fixed.

36. power supply changeover devices as claimed in claim 30, is characterized in that, when described second buck-boost mode, the responsibility cycle of described first switch is fixed.

The control method of 37. 1 kinds of buck-boost power converters, described power supply changeover device comprises an inductance, one first switch is connected between the input of described power supply changeover device and the first end of described inductance, one first diode has an anode and connects the first end that an earth terminal and a negative electrode connect described inductance, between the second end that one second switch is connected to described inductance and described earth terminal, and one second diode there is an anode connect the output that the second end of described inductance and a negative electrode connect described power supply changeover device, it is characterized in that described control method comprises the following steps:

One first frequency and a second frequency are provided;

More described secondary signal and the 3rd signal produce one the 5th signal;

First and second switch described is controlled according to the operator scheme of described power supply changeover device, the described 5th and the 6th signal, first frequency and second frequency;

When first and second buck-boost mode described, the control of first and second switch described comprises:

A, close described first switch, close described second switch;

B, open described first switch, maintain described second switch and close; And

C, maintain described first switch opens, open described second switch.

38. control methods as claimed in claim 37, it is characterized in that, the step that the described power supply changeover device of described decision operates in decompression mode, the first buck-boost mode, the second buck-boost mode or boost mode comprises:

39. control methods as claimed in claim 37, is characterized in that, when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first and second switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first and second switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; When described boost mode, the switching cycle of described second switch is a period 4 being less than second and third cycle described.

40. control methods as claimed in claim 37, it is characterized in that, when described first buck-boost mode, the responsibility cycle of described second switch is fixed.

41. control methods as claimed in claim 37, is characterized in that, when described second buck-boost mode, the responsibility cycle of described first switch is fixed.

42. 1 kinds of buck-boost power converters, is characterized in that, comprising:

One inductance;

One second diode, has an anode and connects the output that the second end of described inductance and a negative electrode connect described power supply changeover device; And

Wherein, described control circuit comprises:

One frequency generator, provides a first frequency and a second frequency;

One control logic circuit, the switching of first and second switch according to described 3rd, the 6th and the 7th signal and first and second FREQUENCY CONTROL;

Wherein, when first and second buck-boost mode described, the control of first and second switch described comprises a, closes described first switch and close described second switch, b, open described first switch and maintain described second switch and close, and c, described first switch opens of maintenance and open described second switch.

43. power supply changeover devices as claimed in claim 42, it is characterized in that, described control circuit, when the multiplier value at the described inductance two ends determined when the load current on the voltage on described input and output and described output is less than first critical value, determines that described power supply changeover device operates in described decompression mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described first critical value and is less than second critical value, determine that described power supply changeover device operates in described first buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is less than one the 3rd critical value and is greater than described second critical value, determine that described power supply changeover device operates in described second buck-boost mode; When the multiplier value at the described inductance two ends that the load current on the voltage on described input and output and described output determines is greater than described 3rd critical value, determine that described power supply changeover device operates in described boost mode.

44. power supply changeover devices as claimed in claim 42, it is characterized in that, described control logic circuit comprises:

45. power supply changeover devices as claimed in claim 44, it is characterized in that, described frequency eliminator comprises D type flip-flop.

46. power supply changeover devices as claimed in claim 42, is characterized in that, when described decompression mode, the switching cycle of described first switch is a period 1; The switching cycle of first and second switch described in when described first buck-boost mode is a second round being greater than the described period 1; The switching cycle of first and second switch described in when described second buck-boost mode is a period 3 being greater than the described period 1; When described boost mode, the switching cycle of described second switch is a period 4 being less than second and third cycle described.

47. power supply changeover devices as claimed in claim 42, it is characterized in that, when described first buck-boost mode, the responsibility cycle of described second switch is fixed.

48. power supply changeover devices as claimed in claim 42, is characterized in that, when described second buck-boost mode, the responsibility cycle of described first switch is fixed.