CN112467988A - Isolated multi-output power supply system and control circuit and power supply method thereof - Google Patents
Isolated multi-output power supply system and control circuit and power supply method thereof Download PDFInfo
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- CN112467988A CN112467988A CN202011091675.3A CN202011091675A CN112467988A CN 112467988 A CN112467988 A CN 112467988A CN 202011091675 A CN202011091675 A CN 202011091675A CN 112467988 A CN112467988 A CN 112467988A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33561—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having more than one ouput with independent control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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Abstract
The invention provides an isolated multi-output power supply system, a control circuit and a power supply method thereof. The isolated multiplexed output power supply system includes: a primary side circuit; a transformer comprising a primary winding and at least one secondary winding; the first output circuit comprises a first one-way conduction device and a switching tube which are coupled with a secondary winding, and the first output circuit provides a first output voltage; a second output circuit comprising a second unidirectional conducting device coupled to a secondary winding, the second output circuit providing a second output voltage; and the control circuit is used for acquiring a sampling signal representing the second output voltage to control the on and off of the switching tube. The multi-output power supply system, the control circuit and the power supply method thereof can be used for accurately controlling the multi-output, and the system has a simple structure and higher efficiency.
Description
Technical Field
The invention relates to the field of electronics, in particular but not exclusively to an isolated multi-output power supply system, a control circuit and a power supply method thereof.
Background
In an electronic power supply system, it is often necessary to provide different power supply sources for different loads in the system. In the field of home appliances, for example, different power supplies are required for different components, such as motors, processing units, etc. One conventional method is to provide independent power supplies for different loads, but this method has a low integration level and a high system power cost. In order to improve the integration degree of a power supply system and reduce the cost of a power supply source, the requirement for a multi-output power supply system is provided.
In a conventional multi-output power supply system, a main circuit output and a sub circuit output are often arranged in a voltage conversion circuit system. The main path output is provided by a conventional voltage conversion topology. The output of the auxiliary circuit is provided with a low dropout linear voltage regulator (LDO) at the output end of the main circuit. However, in this method, the LDO has high power consumption and low system efficiency due to a large output current and a large difference between the auxiliary output voltage value and the main output voltage value.
Another power supply method is to set two isolated output circuits on the secondary side of the isolated power supply, but because of the feedback problem, only one output voltage can be controlled. When the load change or overload occurs in the output of the path, the abnormal change of the output of the other path is often caused and the adjustment cannot be performed.
In view of the above, there is a need to provide a new structure or control method to solve at least some of the above problems.
Disclosure of Invention
The invention provides an isolated multi-output power supply system, a control circuit and a power supply method thereof, aiming at one or more problems in the prior art.
According to one aspect of the present invention, an isolated multi-output power supply system includes: a primary side circuit including a primary side switch; the transformer comprises a primary winding and at least one secondary winding, wherein the primary winding is coupled with a primary side switch; the first output circuit comprises a first one-way conduction device and a switching tube which are coupled with the secondary winding, and the first output circuit provides a first output voltage at a first output end; a second output circuit comprising a second unidirectional conducting device coupled to the secondary winding, the second output circuit providing a second output voltage at a second output terminal, wherein the second output voltage is greater than the first output voltage; and the control circuit is provided with a signal input end and an output end, wherein the signal input end of the control circuit is coupled with the second output end and used for acquiring a sampling signal representing the second output voltage, and the output end of the control circuit is coupled with the control end of the switch tube and used for controlling the switch tube to be switched on and off.
In one embodiment, the power conversion circuit in the isolated multi-output power supply system is a flyback voltage conversion circuit.
In one embodiment, the multiple output power supply system further comprises: the isolated feedback loop detects the first output voltage to generate a feedback signal; and the primary side control circuit is coupled with the primary side switch and controls the primary side switch based on a feedback signal.
In one embodiment, the control circuit includes a comparison circuit for comparing the sampling signal with a threshold signal, wherein the switching tube is in a conducting state when the primary switch is turned off, and the control circuit turns off the switching tube when the control circuit detects that the sampling signal is less than the threshold signal.
In one embodiment, the control circuit further includes a window time control circuit, the window time control circuit obtains a signal representing the turn-off of the primary side switch based on the terminal voltage of the switching tube, sets a window time within a preset time after the turn-off of the primary side switch, and controls the switching tube to be turned on at the end of the window time.
In one embodiment, the control circuit includes a comparison circuit for comparing the sampling signal with a threshold signal, wherein when the primary switch is turned off, the switching tube is in an off state, and when the control circuit detects that the sampling signal is greater than the threshold signal, the control circuit turns on the switching tube.
In one embodiment, the transformer includes a secondary winding, the first unidirectional device includes a first diode, the second unidirectional device includes a second diode, an anode terminal of the first diode is coupled to an anode terminal of the second diode and further coupled to a first terminal of the secondary winding, a second terminal of the secondary winding is coupled to a ground reference of the secondary winding, a cathode terminal of the first diode is coupled to a first terminal of the switching tube, a second terminal of the switching tube is coupled to a first output terminal, and a cathode terminal of the second diode is coupled to a second output terminal.
In one embodiment, the at least one secondary winding includes a first secondary winding and a second secondary winding, wherein the first secondary winding is coupled to the first unidirectional conducting device and the second secondary winding is coupled to the second unidirectional conducting device.
In one embodiment, the second output voltage is used to power the control circuit.
According to another aspect of the present invention, a control circuit for an isolated multi-output power supply system is provided, wherein the isolated multi-output power supply system provides a first output voltage at a first output terminal of a secondary side and a second output voltage at a second output terminal, the control circuit has a signal input terminal and an output terminal, wherein the signal input terminal of the control circuit is coupled to the second output terminal for obtaining a sampling signal representing the second output voltage, and the output terminal of the control circuit is coupled to a control terminal of a switching tube for controlling the switching tube to be turned on and off, wherein the switching tube is coupled to the first output terminal.
In one embodiment, the control circuit includes a comparison circuit, the input terminal of which receives the sampling signal and the threshold signal, and the output terminal of which is coupled to the control terminal of the switch tube.
According to another aspect of the present invention, a method for providing multiple outputs in an isolated voltage converting circuit is provided, which includes: coupling a first one-way conduction device and a switching tube with a secondary winding of the isolated voltage conversion circuit to provide a first output voltage; coupling a second unidirectional conducting device to the secondary winding for providing a second output voltage; controlling the switching tube to be switched on and off based on the second output voltage; and controlling a primary side switch of the isolated voltage conversion circuit based on the first output voltage.
In one embodiment, the method further comprises: when the primary side switch is turned off, the secondary side winding starts to continue current, and the switching tube is in a conducting state; and when the second output voltage is smaller than the set threshold, the switching tube is controlled to be switched off.
The multi-output power supply system, the control circuit and the power supply method thereof can be used for accurately controlling the multi-output, and the system has a simple structure and higher efficiency.
Drawings
FIG. 1 is a block diagram of an isolated multi-output power supply system according to an embodiment of the invention;
FIG. 2 is a schematic circuit diagram of an isolated multi-output power supply system according to an embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of an isolated multi-output power supply system according to another embodiment of the present invention;
FIG. 4 shows a block diagram of a multiple output power supply system according to another embodiment of the present invention;
FIG. 5 illustrates a waveform diagram of a multiple output power supply system according to an embodiment of the present invention;
fig. 6 is a flow chart illustrating a method for providing multiple outputs in an isolated voltage converting circuit according to an embodiment of the present invention.
The same reference numbers in different drawings identify the same or similar elements or components.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. Combinations of different embodiments, and substitutions of features from different embodiments, or similar prior art means may be substituted for or substituted for features of the embodiments shown and described.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or through an intermediate circuit or component as described in the embodiments in the specification; indirect connections may also include connections through other active or passive devices that perform the same or similar function, such as connections through circuits or components such as signal amplification circuits, follower circuits, etc. "plurality" or "plurality" means two or more.
Fig. 1 is a block diagram illustrating an isolated multi-output power supply system according to an embodiment of the present invention. The isolated multi-output power supply system comprises a primary circuit 11, a transformer 12, a first output circuit 13, a second output circuit 14 and a control circuit 15. The first output circuit 13, the second output circuit 14 and the control circuit 15 are located on the secondary side of the isolated multi-output power supply system. The secondary side of the isolated multiple output power supply system obtains energy from the transformer 12 and provides at least two outputs on the secondary side for supplying power to at least two loads. Wherein the primary circuit 11 comprises a primary switch Q. The transformer 12 includes a primary winding (L1, shown in fig. 2 and 3) and at least one secondary winding (L2, or L2 and L3, shown in fig. 2 and 3, respectively), wherein the primary winding L1 is coupled to a primary switch Q, and the power supply system transfers energy from the primary side to the secondary side through the transformer 12 by controlling the switching of the primary switch Q. The first output circuit 13 includes a first unidirectional conducting device D1 coupled to a secondary winding and a switching tube K, and the first output circuit 13 provides a first output voltage Vout1 at a first output terminal OUT 1. The second output circuit 14 includes a second unidirectional pass device D2 coupled to a secondary winding, the second output circuit 14 providing a second output voltage Vout2 at a second output terminal OUT2, wherein the second output voltage Vout2 is greater than the first output voltage Vout 1. The control circuit 15 has a signal input terminal VS and an output terminal Gate, wherein the signal input terminal of the control circuit 15 is coupled to the second output terminal OUT2 for obtaining the sampling signal VS representing the second output voltage Vout2, and the output terminal of the control circuit 15 is coupled to the control terminal of the switching tube K for controlling the switching tube K to be turned on and off. This is used to control the second output voltage Vout2 by controlling the on and off of the switch K. Meanwhile, the first output voltage Vout1 is fed back to the primary side circuit through an isolation type feedback control loop to control the primary side switch Q. Therefore, the simultaneous control of the two paths of outputs can be realized, and when one path of output is abnormal, the other path of output can still be effectively regulated.
In the illustrated embodiment, the first unidirectional conducting device D1 and the second unidirectional conducting device D2 are located at one side of the secondary winding at the output terminal, i.e., the high side, but the first unidirectional conducting device D1 and the second unidirectional conducting device D2 may also be located at one side of the secondary winding at the secondary reference ground, i.e., the low side.
In the illustrated embodiment, the first unidirectional device D1 is a diode, an anode of the diode is coupled to the secondary winding of the transformer 12, a cathode of the first unidirectional device D1 is coupled to the switch tube K, and another end of the switch tube K is coupled to the first output capacitor C1 for providing the first output voltage. However, in another embodiment, the order of the switch tube K and the first unidirectional conducting device D1 may be interchanged.
Fig. 2 is a circuit diagram of an isolated multi-output power supply system according to an embodiment of the invention. The isolated multi-output power supply system comprises a flyback voltage conversion circuit. The isolated multi-output power supply system comprises a primary side switch Q, a transformer 22, a first output circuit 23, a second output circuit 24 and a control circuit 25. The transformer comprises a primary winding L1 and a secondary winding L2. The dotted terminal of the primary winding L1 is coupled to the primary switch Q, and the dotted terminal of the primary winding receives the dc input voltage Vin. In one embodiment, the dc input voltage Vin is obtained by the rectifying and filtering circuit 210 based on the ac power Vac. The dotted terminal of the secondary winding L2 is coupled to the anode terminal of the first unidirectional conducting device D1 and the anode terminal of the second unidirectional conducting device D2, and the different-dotted terminal of the secondary winding L2 is connected to the secondary reference ground. In the illustrated embodiment, the first and second unidirectional conducting devices D1 and D2 are diodes. The cathode of the diode D1 is connected to the first terminal of the switch K, and the second terminal of the switch K is coupled to the first output capacitor C1 and is used for providing the first output voltage Vout1 at the first output terminal. The cathode of the diode D2 is coupled to the second output capacitor C2 and is used for providing the second output voltage Vout2 at the second output terminal. Wherein the control circuit 25 receives a sampling signal VS representing the second output voltage Vout2 and controls the switching tube K based on a comparison of the sampling signal VS and a threshold signal Vth. The sampling signal VS may be a signal proportional to the second output voltage Vout2, such as obtained by a voltage dividing resistor. The multi-output power supply system further comprises an isolation type feedback loop 26 and a primary side control circuit 211, wherein the feedback loop 26 detects a first output voltage Vout1 for generating a feedback signal FB; the primary side control circuit 211 is coupled to the primary side switch Q, and the primary side control circuit 211 controls the primary side switch Q based on the feedback signal FB for controlling the first output voltage Vout 1. In one embodiment, the isolated feedback loop 26 may include a secondary feedback circuit and an optocoupler, where the optical signal is used to transmit the signal generated by the secondary first output voltage Vout1 through the secondary feedback circuit to the primary side. Wherein the secondary feedback circuit may comprise a controllable precision voltage regulator TL431 known to those skilled in the art.
In the embodiment shown in fig. 2, the control circuit 25 comprises a comparison circuit for comparing the sampling signal VS and the threshold signal Vth. In one embodiment, when the primary switch Q is turned off, the control circuit 25 controls the switching tube K to be in a conducting state, and at this time, since the first output voltage Vout1 is lower than the second output voltage Vout2, the energy in the secondary winding L1 is preferentially supplied to the first output circuit 23, the first output voltage Vout1 is raised, and the second output voltage Vout2 is lowered, when the control circuit 25 detects that the second output voltage Vout2 is too low, for example, the sampling signal VS is smaller than the threshold signal Vth, the control circuit 25 turns off the switching tube K, so that the energy transmitted to the secondary winding L2 at the primary side stops being supplied to the first output circuit 23 and the rest of the energy is supplied to the second output circuit 24 completely, so that the second output voltage Vout2 is raised, and the waveform diagram of the control process is shown in fig. 5. If the secondary winding finishes freewheeling and Vout2 is high, the time that the sampling signal VS in the next period is less than the threshold signal Vth is delayed, and the turn-off time of the switching tube K is delayed to transmit more energy to the first output circuit 23; if Vout2 is low when the secondary winding finishes freewheeling, the turn-off time of the switching tube K in the next cycle is advanced, and more energy is transferred to the second output circuit 24. Meanwhile, a primary side switch Q is controlled by detecting a first output voltage Vout1, energy transmitted from a primary side to a secondary side is regulated, regulation of the first output voltage Vout1 and the second output voltage Vout2 is achieved, and the values of the first output voltage Vout1 and the second output voltage Vout2 are respectively and dynamically regulated to be close to preset values.
With continued reference to fig. 2. In one embodiment, the control circuit 25 further includes a window time control circuit, which obtains a signal representing the state of the primary switch Q based on the terminal voltage of the switching tube K, and sets a window time based on the state of the primary switch Q, and the control circuit 25 further controls the switching tube K to be turned on or off based on the window time. In one embodiment, the window time control circuit obtains a signal representing turn-off of the primary side switch based on the terminal voltage of the switching tube, and sets the window time within a preset time after the primary side switch is turned off, the control circuit 25 controls the switching tube K to be in a conducting state at the beginning of secondary side follow current, the switching tube K is turned off when a sampling signal Vs of the second output voltage Vout2 is lower than a threshold signal Vth, the control circuit 25 controls the switching tube K to be turned off only within the window time, and the control circuit 25 controls the switching tube K to be turned on when the window time is over. In another embodiment, the control circuit 25 controls the switching tube to be in an off state when the secondary-side freewheeling begins, the switching tube K is turned on when the sampling signal Vs is greater than the threshold signal Vth, and the control circuit 25 controls the switching tube K to be turned off when the window time ends. The terminal voltage of the switching tube K includes a voltage of a first terminal (e.g., a drain terminal) of the switching tube and/or a voltage of a second terminal (e.g., a source terminal), and when the primary switch Q is turned off, a difference between the first terminal voltage and the second terminal voltage is greater than a predetermined threshold. In another embodiment, the control circuit 25 obtains a signal indicating that the primary side switch Q is turned on based on the terminal voltage of the switching tube K, and the control circuit 25 controls the switching tube K to turn on the switching tube K during the turn-on period of the primary side switch Q, for example, controls the switching tube K to turn on when the turn-on of the primary side switch Q is detected or after a predetermined time of the turn-on.
In one embodiment, the multiple output power supply system further comprises a controllable device, such as a resistor or a capacitor, external to the control circuit 25 for adjusting the window time length of the window time control circuit.
In another embodiment, when the primary switch Q is turned off, the control circuit 25 controls the switching tube K to be turned off or kept turned off, at which time the energy in the secondary winding L2 is provided to the second output circuit 24, the second output voltage Vout2 rises, when Vout2 rises to a preset threshold, that is, when the sampling signal VS is greater than the threshold signal Vth, the switching tube K is controlled to be turned on, so that the energy remaining in the secondary winding L2 is used to provide the first output circuit 23, and the first output voltage Vout1 rises until the freewheeling current in the secondary winding becomes zero or the primary switch Q is turned on again. If the first output voltage Vout1 is higher than the preset value when the current in the secondary winding L2 finishes afterflow, the primary switch Q is controlled by the isolation feedback loop 26, the turn-on time of the primary switch Q in the next period is reduced, and the energy transmitted to the secondary is reduced. If the first output voltage Vout1 is lower than the preset value when the follow current is finished, the energy transferred to the secondary side is increased by controlling the primary side Q. In this way, the control of the first output voltage Vout1 and the second output voltage Vout2 can be simultaneously achieved.
In the embodiment shown in fig. 2, the switching tube K is controlled based on the sampling of the second output voltage Vout2, so that the second output voltage Vout2 can be accurately controlled, and meanwhile, the primary side switch Q is controlled by the isolation feedback loop 26, so that the first output voltage Vout1 can be controlled, and thus the circuit can simultaneously realize the accurate control of two-way output.
In the embodiment shown in fig. 2, in which the transformer 22 comprises only one secondary winding L2, the first output circuit 23 and the second output circuit 24 share the secondary winding L2. The anode terminal of the first unidirectional conducting device D1 is coupled to the anode terminal of the second unidirectional conducting device D2 and further coupled to the first terminal (dotted terminal) of the secondary winding L2, the second terminal (dotted terminal) of the secondary winding L2 is coupled to the reference ground of the secondary, the cathode terminal of the first unidirectional conducting device D1 is coupled to the first terminal of the switching tube K, the second terminal of the switching tube K is coupled to the first output terminal OUT1, and the cathode terminal of the second unidirectional conducting device D2 is coupled to the second output terminal OUT 2.
In the embodiment shown in fig. 2, the isolated multi-output power supply system includes a flyback voltage conversion circuit. In another embodiment, the isolated multi-output power supply system may include other topology types, such as a forward voltage conversion circuit, and the like, wherein one output voltage is controlled by an isolated loop, and the other output voltage is controlled by the turn-off action of the switching tube to transfer energy to the switching tube, thereby implementing precise control of two paths. Of course, the secondary side of the isolated multi-output power supply system may further include more output circuits, and the output of the output circuits may be changed or adjusted in other ways.
Fig. 3 shows a circuit schematic of a multiple output power supply system according to an embodiment of the invention. In contrast to the embodiment of fig. 2, the secondary winding of the transformer 32 of fig. 3 comprises a first secondary winding L2 and a second secondary winding L3. The first secondary winding L2 is coupled to the first unidirectional conducting device D1 for supplying energy to the first output circuit 33, and the second secondary winding L3 is coupled to the second unidirectional conducting device D2 for supplying energy to the second output circuit 34. In the illustrated embodiment, the first unidirectional conducting device D1 and the second unidirectional conducting device D2 are located on the same-name end side of the secondary windings, and are high-order rectifying tubes. In other embodiments, the first unidirectional conducting device D1 and/or the second unidirectional conducting device D2 may also be located on the side of the respective secondary winding near the reference ground end as a low-side rectifier. In the illustrated embodiment, the isolated feedback loop for providing the feedback signal FB comprises a signal processing circuit on the secondary side and an optocoupler, wherein the optocoupler comprises a light emitter on the secondary side and a light receiver on the primary side for feeding back the first output voltage Vout1 signal to the primary side circuit.
Fig. 4 shows a block diagram of a multiple output power supply system according to an embodiment of the invention. Compared with the embodiment shown in fig. 1, the control circuit 45 for controlling the switch K in the first output circuit 43 further has a power supply terminal VDD, wherein the power supply terminal VDD is coupled to the second output voltage Vout2 output by the second output circuit 44, so that the second output voltage Vout2 is directly used for supplying power to the control circuit 45. The second output voltage Vout2 is based on a sampling circuit, such as a voltage divider circuit as shown, that provides a sampling signal VS proportional to the second output voltage Vout 2.
Fig. 5 shows a waveform diagram of a multiple output power supply system according to an embodiment of the invention. Referring to fig. 2, signals from top to bottom are a control signal PWM for controlling the primary switch Q, a primary current Ip flowing through the primary winding L1, a secondary current Is flowing through the secondary winding L2, a switch control signal CTR for controlling the switching tube K, a first current Is1 flowing through the first diode D1, and a second current Is2 flowing through the second diode D2, respectively. At time t1, the PWM signal Is set high, the primary switch Q Is turned on, the primary current Ip rises, the secondary diodes D1 and D2 are reverse biased off, and the secondary current Is zero. At time t2, the PWM changes from high to low, the primary switch Q Is turned off, the primary current Ip becomes zero, the secondary winding voltage Is reversed, the secondary diodes D1 and D2 are forward biased, the energy stored by the transformer Is released in the form of a secondary current Is through the secondary winding L2, and the secondary current Is at a maximum value. At this time, the switch control signal CTR Is in a high state, the switching transistor K Is in a conducting state, and since the first output voltage Vout1 Is lower than Vout2, the secondary current Is preferentially supplied to the first output circuit 23, and the first output voltage Vout1 rises. The second output voltage Vout2 drops in voltage during consumption. At time t3, when the second output voltage Vout2 is lower than the set threshold, the control circuit 25 controls the switch signal CTR to go low, and the switch transistor K is turned off. The remaining energy on the secondary side of the flyback voltage converter circuit is provided to the second output circuit 24, and the second output voltage Vout2 rises until the freewheeling is over or the primary switch is turned on again. In one embodiment, the flyback voltage conversion circuit employs a critical control mode (BCM) that turns on the primary switch when the secondary current drops to zero. In one embodiment, the flyback voltage conversion circuit employs discontinuous current mode (CCM). At time t4, the PWM signal is again set high for turning on the primary switch Q and a new switching cycle begins. Thus, the system preferentially supplies power to the first output circuit 23, so that the voltage at the first end of the secondary winding L2 rises to the first output voltage, and then switches to the second output voltage and higher, the voltages at the anode ends of the first diode D1 and the second diode D2 are in a rising state, and the switching loss caused by the reverse current of the first diode D1 or the second diode D2 is reduced.
Fig. 6 is a flow chart illustrating a method for providing multiple outputs in an isolated voltage converting circuit according to an embodiment of the present invention. The method includes coupling a first one-way pass device D1 and a switch K to a secondary winding of an isolated voltage translation circuit for providing a first output voltage Vout1 at step 601. In one embodiment, the first unidirectional device D1 includes a first diode D1 having an anode coupled to the secondary winding and a cathode coupled to a switch K, the other end of the switch K being coupled to a first output terminal, the first output terminal providing the first output voltage Vout 1. The method includes coupling a second unidirectional conducting device D2 with the secondary winding for providing a second output voltage Vout2 at step 602, wherein the second output voltage Vout2 is higher than the first output voltage Vout 1. In one embodiment, the second unidirectional conducting device D2 includes a second diode having an anode coupled to the secondary winding and a cathode coupled to a second output terminal providing the second output voltage. The first one-way conduction device and the second one-way conduction device can be coupled with the same end of the same secondary winding and can also be coupled with different secondary windings. The method includes controlling the switching transistor K to turn on and off based on the second output voltage Vout2 at step 603. In one embodiment, when the primary side switch is turned off, the secondary side winding starts to continue current, and the switching tube K is controlled to be switched on; when the second output voltage Vout2 is smaller than the set threshold, the switching tube K is controlled to be turned off. In another embodiment, when the primary side switch is turned off, the secondary side winding starts to continue current, and the control switch tube K is in an off state firstly, so that the second one-way conduction device is conducted; when the second output voltage Vout2 is greater than the set threshold, the switching transistor K is controlled to be turned on to turn on the first unidirectional conducting device. The method further includes controlling a primary side switch of the isolated voltage conversion circuit based on the first output voltage at step 604. In one embodiment, the system feeds back the first output voltage to the primary side through a secondary side feedback circuit and an optocoupler. Wherein the secondary feedback circuit may comprise a controllable precision voltage regulator TL431 known to those skilled in the art. Through the control, the first output voltage and the second output voltage can be accurately regulated at the same time, and the problem of cross alignment rate is solved.
Those skilled in the art should understand that the logic controls such as "high" and "low", "set" and "reset", "and gate" and "or gate", "non-inverting input" and "inverting input" in the logic controls referred to in the specification or the drawings may be exchanged or changed, and the subsequent logic controls may be adjusted to achieve the same functions or purposes as the above-mentioned embodiments.
The description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The descriptions related to the effects or advantages in the specification may not be reflected in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the descriptions related to the effects or advantages are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (13)
1. An isolated multi-output power supply system comprising:
a primary side circuit including a primary side switch;
the transformer comprises a primary winding and at least one secondary winding, wherein the primary winding is coupled with a primary side switch;
the first output circuit comprises a first one-way conduction device and a switching tube which are coupled with the secondary winding, and the first output circuit provides a first output voltage at a first output end;
a second output circuit comprising a second unidirectional conducting device coupled to the secondary winding, the second output circuit providing a second output voltage at a second output terminal, wherein the second output voltage is greater than the first output voltage; and
and the control circuit is provided with a signal input end and an output end, wherein the signal input end of the control circuit is coupled with the second output end and used for acquiring a sampling signal representing the second output voltage, and the output end of the control circuit is coupled with the control end of the switch tube and used for controlling the switch tube to be switched on and off.
2. The multiple output power supply system of claim 1 including a flyback voltage conversion circuit.
3. The multi-output power supply system of claim 2 further comprising:
the isolated feedback loop detects the first output voltage to generate a feedback signal;
and the primary side control circuit is coupled with the primary side switch and controls the primary side switch based on a feedback signal.
4. The multi-output power supply system of claim 3 wherein the control circuit includes a comparison circuit for comparing the sampled signal to a threshold signal, wherein the switching tube is in the on state when the primary switch is off and the control circuit turns off the switching tube when the control circuit detects that the sampled signal is less than the threshold signal.
5. The multi-output power supply system according to claim 4, wherein the control circuit further comprises a window time control circuit for obtaining a signal indicative of the turn-off of the primary side switch based on the terminal voltage of the switching tube, and setting a window time within a preset time after the turn-off of the primary side switch, the control circuit controlling the switching tube to turn on at the end of the window time.
6. The multi-output power supply system of claim 3 wherein the control circuit includes a comparison circuit for comparing the sampled signal to a threshold signal, wherein the switching tube is in an off state when the primary switch is off and the control circuit turns on the switching tube when the control circuit detects that the sampled signal is greater than the threshold signal.
7. The multi-output power supply system of claim 2 wherein the transformer includes a secondary winding, the first unidirectional device includes a first diode, the second unidirectional device includes a second diode, an anode of the first diode is coupled to an anode of the second diode and further coupled to a first terminal of the secondary winding, a second terminal of the secondary winding is coupled to a ground reference of the secondary winding, a cathode of the first diode is coupled to a first terminal of the switching tube, a second terminal of the switching tube is coupled to the first output terminal, and a cathode of the second diode is coupled to the second output terminal.
8. The multiplexed output power supply system of claim 2 wherein the at least one secondary winding comprises a first secondary winding and a second secondary winding, wherein the first secondary winding is coupled to the first unidirectional conducting device and the second secondary winding is coupled to the second unidirectional conducting device.
9. The multi-output power supply system of claim 2 wherein the second output voltage is used to power the control circuit.
10. A control circuit for an isolated multi-output power supply system is provided, wherein the isolated multi-output power supply system provides a first output voltage at a first output end of a secondary side and provides a second output voltage at a second output end, the control circuit is provided with a signal input end and an output end, the signal input end of the control circuit is coupled with the second output end and used for obtaining a sampling signal representing the second output voltage, the output end of the control circuit is coupled with a control end of a switching tube and used for controlling the switching-on and switching-off of the switching tube, and the switching tube is coupled with the first output end.
11. The control circuit of claim 10, wherein the control circuit comprises a comparator circuit having an input terminal receiving the sampling signal and the threshold signal and an output terminal coupled to the control terminal of the switch tube.
12. A power supply method for providing multi-path output in an isolated voltage conversion circuit comprises the following steps:
coupling a first one-way conduction device and a switching tube with a secondary winding of the isolated voltage conversion circuit to provide a first output voltage;
coupling a second unidirectional conducting device to the secondary winding for providing a second output voltage;
controlling the switching tube to be switched on and off based on the second output voltage; and
and controlling a primary side switch of the isolated voltage conversion circuit based on the first output voltage.
13. The method of claim 12, further comprising: when the primary side switch is turned off, the secondary side winding starts to continue current, and the switching tube is in a conducting state; and when the second output voltage is smaller than the set threshold, the switching tube is controlled to be switched off.
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| CN202011091675.3A CN112467988A (en) | 2020-10-13 | 2020-10-13 | Isolated multi-output power supply system and control circuit and power supply method thereof |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020093315A1 (en) * | 2001-01-17 | 2002-07-18 | Sluijs Ferdinand Jacob | Controlled multi-output DC/DC converter |
| CN1525632A (en) * | 2002-12-18 | 2004-09-01 | 因芬尼昂技术股份公司 | Method for generating direct voltage, circuit device and switch-mode adjusting monitoring module |
| CN111082667A (en) * | 2020-01-22 | 2020-04-28 | Msj系统有限责任公司 | Multi-output switching power supply |
| CN111146930A (en) * | 2020-01-22 | 2020-05-12 | 矽力杰半导体技术(杭州)有限公司 | Power converter |
-
2020
- 2020-10-13 CN CN202011091675.3A patent/CN112467988A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020093315A1 (en) * | 2001-01-17 | 2002-07-18 | Sluijs Ferdinand Jacob | Controlled multi-output DC/DC converter |
| CN1525632A (en) * | 2002-12-18 | 2004-09-01 | 因芬尼昂技术股份公司 | Method for generating direct voltage, circuit device and switch-mode adjusting monitoring module |
| CN111082667A (en) * | 2020-01-22 | 2020-04-28 | Msj系统有限责任公司 | Multi-output switching power supply |
| CN111146930A (en) * | 2020-01-22 | 2020-05-12 | 矽力杰半导体技术(杭州)有限公司 | Power converter |
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