WO2016150245A1

WO2016150245A1 - Dc/dc converter

Info

Publication number: WO2016150245A1
Application number: PCT/CN2016/071517
Authority: WO
Inventors: 王跃斌; 宋栋梁; 崔荣明
Original assignee: 深圳市皓文电子有限公司
Priority date: 2015-03-23
Filing date: 2016-01-20
Publication date: 2016-09-29
Also published as: CN104734520A

Abstract

A DC/DC converter comprises an inverter unit, a resonance unit, a high-frequency transformer, and a rectification and filtering unit. The inverter unit comprises half-bridge circuits that are under the action of asymmetrical and complementary pulse-width modulation control signals, or comprises a full-bridge circuit under the control of the constant-frequency phase-shift, so as to convert direct-current input into square waves. The resonance unit obtains square weaves output by the inverter unit and makes the square weaves resonant. The resonance unit comprises a resonance inductor, a first resonance capacitor, and a second resonance capacitor. The rectification and filtering unit combines current-doubler rectification, full-wave rectification or full-bridge rectification mode with various types of LC filtering, and converts an alternating-current waveform on a secondary side of the high-frequency transformer into direct-current output. The DC/DC converter has a simple control mode, a small output ripple and a high conversion efficiency, and the transformer has simple design.

Description

A DC/DC converter

Technical field

This invention relates to power supplies and, more particularly, to a DC/DC converter.

Background technique

Generally speaking, the resonant network is applied to the power conversion circuit, which can effectively reduce the switching loss and noise of the circuit, reduce the electromagnetic interference, reduce the voltage and current pressure of the device, improve the switching frequency, improve the efficiency, reduce the volume weight, and improve the power for the converter. Density creates good conditions. At present, the widely used LLC resonant topology adopts PFM control in the control method, that is, the switching frequency is changed, which makes the design of the control method complicated; when using PFM control, the transformer needs to be designed according to the lowest operating frequency, and the design of the transformer itself is complicated. The parameters are difficult to optimize; in the synchronous rectification circuit, the synchronous rectification drive circuit is complicated due to the variable frequency control; the LLC resonant topology output usually adopts capacitive filtering, and the capacitor bears the resonant ripple current, which is not only large in loss, but also has serious heat generation and large output ripple. . Therefore, it is necessary to seek a circuit or a combination of a circuit and a control method not only to realize the soft switching of the switching tube in a wide load range, but also to simplify the design of the transformer and the secondary side synchronous rectification driving.

Summary of the invention

The technical problem to be solved by the present invention is to provide a method for the above-mentioned resonant network of the prior art, which is complicated in control mode, cannot optimize the transformer design, has difficulty in designing the secondary side synchronous rectification drive control, and has large output ripple. The control method is simple, the transformer can optimize the design, the synchronous rectification drive control circuit is simple in design, and the output ripple current is small, a DC/DC converter.

The technical solution adopted by the present invention to solve the technical problem is to construct a DC/DC converter including an inverter unit, a resonance unit, a high frequency transformer and a rectification and filtering unit; the inverter unit includes a half bridge circuit in an asymmetry a complementary pulse width modulated control signal or a full bridge circuit converts a DC input into a square wave under constant frequency phase shift control; the resonant unit obtains a square wave of its output by the inverter unit and causes Resonating and transmitting it to the primary side of the high-frequency transformer; the rectifying and filtering unit adopts double current rectification, full-wave rectification or full-bridge rectification and converts the alternating current waveform on the secondary side of the high-frequency transformer by LC filtering Switch to DC output.

Further, the inverter unit includes a half bridge circuit composed of a first controlled switch tube and a second controlled switch tube, and one end of the DC input sequentially passes through the two switch ends of the first switch tube and the second switch tube. The two switch ends are connected to the other end of the DC input; the two switch tubes are respectively controlled by their asymmetric, complementary pulse width modulation signals input from the control terminal; the control end of the first switch tube a pulse width of the upper control signal determines a pulse width of the output square wave of the inverter unit; the resonance unit is obtained by a connection point of the first switch tube and the second switch tube, and one end or the other end of the DC input The square wave output by the inverter unit.

Further, a period of the control signal input by the control ends of the first switch tube and the second switch tube is a set length, and when the duty ratio of the control signal of the first controlled switch is D, the first The duty ratio of the control signal of the two controlled switches is 1-D; the two control signals are respectively advanced or delayed by a set width at their adjacent high and low level switching positions to form a dead zone of the set width to prevent The two switching tubes are simultaneously turned on.

Further, the inverter unit includes a full bridge inverter circuit adopting constant frequency phase shift control; the full bridge inverter circuit includes a first half composed of a first controlled switch tube and a second controlled switch tube a bridge circuit and a second half bridge circuit composed of a third controlled switch tube and a fourth controlled switch tube; one end of the DC input is sequentially connected to the DC input through the two switch ends of the first switch tube and the second switch tube The other end; the one end of the DC input is also connected to the other end of the DC input of the third switch tube and the fourth switch tube; the two switch tubes of one half bridge circuit are respectively input by the control end thereof, and each has A pulse-width modulated signal having a 50% duty cycle and a phase difference of 180 degrees controls its switching; there is a setting between control signals of two controlled switching transistors in the two half-bridge circuits at their topological diagonal positions a phase difference or a phase shift angle, the set phase difference determining a pulse width of the output square wave of the inverter unit; the resonance unit being connected by the first switch tube and the second switch tube and the Third switch tube and Four switch connection point obtaining unit outputs the square wave inverter.

Further, in the first half bridge circuit and the second half bridge circuit, one half bridge The control signals of the two controlled switches in the circuit have equal pulse widths, each having a 50% duty cycle and a phase difference of 180 degrees, and the two control signals are advanced or delayed by one at their adjacent high and low level switching positions, respectively. The width is set to form a dead zone of the set width to prevent the two switches from being turned on at the same time.

Further, the resonant unit includes a resonant inductor, a first resonant capacitor, and a second resonant capacitor, and the resonant inductor and the first resonant capacitor are connected in series with the primary side of the high-frequency transformer in an output of the inverter unit On the two terminals of the square wave, the second resonant capacitor is connected to the primary or secondary side of the high-frequency transformer or the sum of the parallel capacitors of the primary and secondary sides; the resonant inductor is an independent inductor Or the leakage inductance of the transformer or the sum of the two; the second resonant capacitor is a separate capacitor or a rectifier switch parasitic capacitance or a parallel equivalent equivalent of the two.

Further, the primary side of the high frequency transformer is one winding, and the secondary side is one or more windings.

Further, the rectifying and filtering circuit includes a rectifying portion and a filtering portion; the rectifying portion includes a rectifying device, and when rectifying and rectifying, the rectifying device is a diode using a common anode or a common cathode current doubler rectifying circuit or adopting The MOSFET of the synchronous rectification circuit; the filtering part is an LC combined filter circuit.

Further, the rectifying and filtering circuit includes a rectifying portion and a filtering portion; the rectifying portion includes a rectifying device, and the rectifying device is a diode using a common anode or a common cathode rectifying circuit when full-wave or full-bridge rectification; The filtering part is an LC combined filter circuit.

A DC/DC converter embodying the present invention has the following beneficial effects: since the inverter unit uses an asymmetric, complementary PWM drive signal to control the conduction and turn-off of its controlled switch tube, and at the same time, the resonant capacitor in the resonant unit It is connected to the high-frequency transformer. Therefore, the soft switching of the switching tube can be realized in a wide load range, thereby reducing switching loss and EMI, making the filter circuit easy to design. At the same time, the parasitic parameters of the high-frequency transformer will be used as the resonant element, eliminating the pair. In addition, the rectification and filtering unit adopts double current rectification, full-wave rectification or full-bridge rectification plus LC combined filtering, so that its rectifier diodes are naturally commutated without reverse recovery problem. Due to the presence of the resonant unit, the power switch tube is at zero Turning on or off under voltage or zero current conditions realizes soft switching of the power switch tube and improves conversion efficiency.

DRAWINGS

1 is a schematic structural view of a DC/DC converter in an embodiment of a DC/DC converter according to the present invention;

2 is a schematic structural view of a half bridge asymmetric control in the embodiment;

Figure 3 is a schematic view of the driving waveform of Figure 2;

Figure 4 is a waveform diagram at two points of AB in Figure 2;

FIG. 5 is a schematic structural diagram of a phase-shifted full bridge using constant frequency control in the embodiment; FIG.

6 is a schematic diagram of driving waveforms of the inverter unit of FIG. 5;

Figure 7 is a waveform diagram of two points of AB in Figure 5;

Figure 8 is a waveform diagram of the rectifier diode of Figure 5;

Figure 9 is a schematic view showing a modified structure of the DC/DC converter of Figure 2;

Figure 10 is a schematic view showing a modified structure of the DC/DC converter of Figure 5;

11-20 are respectively schematic structural diagrams of a rectifying and filtering unit in an embodiment of the present invention;

21 is a schematic diagram showing a modified structure of an LC circuit in a rectifying and filtering unit according to an embodiment of the present invention;

FIG. 22 is a schematic diagram showing another modified structure of an LC circuit in a rectifying and filtering unit according to an embodiment of the present invention.

detailed description

The embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in FIG. 1, in an embodiment of a DC/DC converter of the present invention, the DC/DC converter includes an inverter unit, a resonance unit, a high frequency transformer, and a rectification filtering unit; The complementary input pulse width modulation (PWM) control signal converts the DC input into a square wave; and the resonant unit obtains the square wave of its output by the above-mentioned inverter unit and resonates it, and the resonant unit includes the parallel connection The resonant capacitor on the high-frequency transformer is described; the rectifying and filtering unit adopts double current rectification, full-wave rectification or full-bridge rectification and converts the alternating current waveform on the secondary side of the high-frequency transformer into a direct current output by LC filtering. Fig. 2 is a circuit diagram showing the structure of a half bridge as an inverter unit in the present invention. In FIG. 2, the inverter unit includes Q ₁ and Q ₂ and its accessory elements, the resonance unit includes L _r , C _s and C _p , and the rectification filtering unit includes D ₁ , D ₂ , L _f1 , L _f2 and C _o , The high frequency transformer is T ₁ , and the resonant capacitor is the capacitors C _s and C _p in FIG. 2; in FIG. 2, the above inverter unit comprises a first controlled switch Q ₁ and a second controlled switch Q ₂ In the first half bridge circuit, one end of the DC input is sequentially connected to the other end of the DC input through the two switch ends of the first controlled switch Q _{1 and} the two switch ends of the second controlled switch Q ₂ ; in the present invention, The controlled switch is a MOS transistor, the two switch ends of which are their source and drain, respectively, and the control end thereof is the gate of the MOS tube; the two controlled switches are respectively input by their control terminals, asymmetrical, The complementary pulse width adjustment control signal controls its switch; that is, a control signal or a drive signal is applied to the gates of the first controlled switch Q ₁ and the second controlled switch Q ₂ described above to control the source and drain thereof. Turning on or off; wherein the pulse width of the control signal on the control end of the first switch Q ₁ determines the output of the inverter unit The pulse width of the square wave also determines the magnitude of the DC power output of the converter; the resonant unit obtains the output of the inverter unit from the connection point of the first controlled switch Q ₁ and the second controlled switch Q ₂ and the other end of the DC input. The square wave, that is, the square wave output from the inverter unit is obtained from two points A and B in Fig. 2 . In the present invention, the total pulse width (i.e., pulse period) of the control signals (drive signals) of the two controlled switches in Fig. 2 is the same, but the effective levels of the two control signals (i.e., control is controlled) The position at which the switch is turned on) is different, specifically asymmetric and complementary; in other words, the durations of the high or low levels of the two signals are unequal, and The duration of the high level of the signals is added equal to the total pulse period, and the sum of the low level durations is also equal to the total pulse period. The relationship between the two signals is: when the duty ratio of the control signal of the first controlled switch Q ₁ is D, the duty ratio of the control signal of the second controlled switch Q ₂ is 1-D; The two control signals are advanced or delayed by a set width at their adjacent positions to form a dead zone of a set width to prevent simultaneous conduction of the two controlled switches. Referring to FIG. 3, in FIG. 3, T _S is the total pulse width of the driving signal, and the pulse width of any one of the control signals cannot be equal to 1/2, that is, the two control signals cannot be symmetric.

In summary, in the DC/DC converter circuit of FIG. 2, V _in is the input side DC power supply; the first controlled switch Q ₁ and the second controlled switch Q ₂ (including the internal parasitic diode and parasitic inductance of the switch) Forming a half bridge; the series resonant inductor L _r , the first resonant capacitor C _s and the second resonant capacitor C _p constitute an LCC resonant network; T ₁ is a high frequency transformer whose primary side is connected in parallel to both ends of the second resonant capacitor C _p The secondary side is connected to the current doubler rectification topology; the current doubler rectification topology is composed of fast recovery diodes D ₁ and D ₂ , output filter inductors L _f1 and L _{f2 ,} and an output filter capacitor C _o ; R _L is a load.

In FIG. 2, the DC input V _{in is} connected to an asymmetric half-bridge topology consisting of a first controlled switch Q ₁ and a second controlled switch Q ₂ , and the PWM drive signal controls the complementary conduction of the two controlled switches and remains There is a certain dead zone (see Figure 3) to avoid straight-through. By controlling the duty cycle to adjust the power, a square wave voltage is generated between the drain and source of the second controlled switch Q ₂ (two points A and B in Figure 2). Applying to the LCC resonant network, the voltage or current flowing through the LCC resonant loop is a sine wave or a quasi-sinusoidal wave, causing the first controlled switch Q ₁ and the second controlled switch Q ₂ to be turned on under zero voltage conditions. The sinusoidal voltage on the primary side (primary side) of the transformer is coupled to the secondary side (secondary side). The voltage is still sinusoidal. The secondary side sinusoidal voltage is connected to the load R _L through the current doubler rectifier circuit, and the rectifier diodes D ₁ and D _{2 are} realized. Natural commutation. The PWM drive signal is shown in Figure 3. The square wave voltage V _AB applied by the inverter unit to the LCC resonant network is as shown in FIG.

It is worth mentioning that in the present invention, the asymmetry or the asymmetry means that the pulse widths of the two driving signals (ie, the width of the effective level) are unequal; and the complementary refers to the high level of the two driving signals. The partial addition (including the previously set dead zone or isolation region at the level of the two drive signal level shifting) is equal to the total width of the drive pulse.

Fig. 2 shows the structure of the inverter unit in some cases in the present invention, and in other cases in the present invention, the above-mentioned inverter unit may also be constituted by two half bridges. Referring to FIG. 5, in FIG. 5, except that the structure and control signals of the inverter unit and the square wave output end are different from those of FIG. 2, the remaining components are substantially the same as those of FIG. In FIG. 5, the inverter unit includes a first half bridge circuit composed of a first controlled switch Q ₁ and a second controlled switch Q ₂ and is composed of a third controlled switch Q ₃ and a fourth controlled switch Q ₄ a second half bridge circuit; one end of the DC input is sequentially connected to the DC through the two switch ends of the first switch Q ₁ and the third switch Q _{3 and} the two switch ends of the second switch Q ₃ and the fourth switch Q ₄ The other end of the input; in other words, the two half bridges are connected in parallel at both ends of the DC input; in the half bridge circuit, the two switch tubes are respectively input by their control terminals, each having a 50% duty ratio and having a phase difference of 180 The pulse width modulation control signal controls its switch; the two half bridge circuits are combined to form a full bridge circuit, which is provided between the control signals of the two controlled switches located at the top diagonal position of the full bridge circuit. A predetermined phase difference or phase shift angle, the set phase difference determines a pulse width of the output square wave of the inverter unit; adjusting the phase difference or the phase shift angle can adjust a DC level of the DC/DC converter output. The resonant unit obtains a square wave output by the inverter unit by a connection point of the first controlled switch Q ₁ and the second controlled switch Q _{2 and} a connection point of the third controlled switch Q ₃ and the fourth controlled switch Q ₄ . See points A and B in Figure 5. In FIG. 5, in the first half bridge circuit and the second half bridge circuit, the control signals of the two controlled switches in one half bridge circuit have the same pulse width and phase difference of 180 degrees, and the two control signals are in the same The adjacent positions are respectively advanced or delayed by a set width to form a dead zone of the set width to prevent the two switch tubes from being simultaneously turned on; and in the combined topology formed by the first half bridge circuit and the second half bridge circuit The control signals between the controlled switches of the diagonal position (for example, between Q ₃ and Q _{2 in} Figure 5 or between Q ₁ and Q ₄ ) differ by a set phase difference, ie there is a shift The phase angle is adjusted by adjusting the phase shift angle to adjust the pulse width of the output of the full bridge inverter circuit. See Figure 6 for the drive signal in Figure 5.

Similarly, in FIG. 5, V _in is the input side of the DC power supply; controlled switch Q ₁ ~ Q ₄ (internal switch comprises a parasitic diode and a parasitic inductance) consisting of two half-bridge phase shift controlled switch Q ₁ And Q ₂ is the first half bridge, the phase of the driving signal is ahead of the second half bridge; the controlled switches Q ₃ and Q ₄ are the second half bridge, the phase lag of the driving signal and the driving signal of the first half bridge The resonant unit also includes a series resonant inductor L _r , a first resonant capacitor C _s and a second resonant capacitor C _{p to} form an LCC resonant network; T ₁ is a high frequency transformer, and the primary side (primary side) is connected in parallel to the second resonant capacitor C _p both ends of the secondary side (secondary side) contact times rectifier topology; Doubler rectifier topology of fast recovery diode D ₁ and D _2, L _f1 and output filter inductor L _f2 and the output filter capacitor C _o composition; R _L is load. It is worth mentioning that in the present invention, the primary side of the high frequency transformer includes only one winding, and the secondary side thereof may include more than one winding.

In FIG. 5, by controlling the controlled switches Q ₁ -Q ₄ by phase shift PWM, a positive and negative alternating pulse square wave (see FIG. 7) is generated between the two points A and B in FIG. 5, and applied to the LCC resonant network. The voltage or current flowing through the LCC resonant tank is a sinusoidal or quasi-sinusoidal wave that causes the controlled switches Q ₁ -Q ₄ to turn "on" and "off" under zero or zero current conditions. The primary side sinusoidal voltage of the transformer is coupled to the secondary side and the voltage is still sinusoidal. The secondary side sinusoidal voltage is connected to the load R _L through the current doubler rectifier circuit, and the rectifier diodes D ₁ and D ₂ realize natural commutation. As shown in FIG 6, PWM1 ~ PWM4 signal to drive the power switch Q ₁ -Q ₄ is, PWM controlled drive switches in half-bridge is turned on and a signal complementary to leave some dead avoid shoot-through; diagonal There is a phase shift angle between the PWM drive signals at the position of the switch, and the power adjustment is performed by controlling the phase shift angle. The square wave voltage V _AB applied to the LCC resonant network is as shown in FIG. The voltage waveforms V _D1 and V _{D1 of the} rectifier diodes D ₁ and D ₂ are as shown in FIG.

As described above, in the present invention, in any of the two cases shown in FIGS. 2 and 5, the resonance unit thereof includes the resonance inductance L _r , the first resonance capacitance C _{s ,} and the second resonance capacitance C _p , wherein the (series) resonant inductor L _r and the first resonant capacitor C _{s are} connected in series with the primary side of the high-frequency transformer and connected to the two terminals of the output square wave of the inverter unit, and the second resonant capacitor C _p is connected in parallel On the primary or secondary side of the high frequency transformer. For an example in which the second resonant capacitor is connected to the secondary side of the high frequency transformer, refer to FIG. 9 and FIG. 10; wherein, when the inverter unit is a half bridge circuit, the second resonant capacitor is connected to the high frequency variable voltage secondary side. The circuit (at this time, the second resonant capacitor includes not only C _{p '} but also the parasitic capacitance of the rectifying device); and FIG. 10 is when the inverter unit is a full-bridge circuit, and the second resonant capacitor is connected to the high-frequency transformer The secondary side of the circuit (at this time, the second resonant capacitor also includes the parasitic capacitance of the rectifying device).

In addition, in the invention, the rectifying and filtering unit includes two rectifying switches, two rectifying switches and a high frequency transformer, which are respectively connected to one end of the high frequency transformer, and the other switch end is connected to the common potential end. a switch end connected at both ends of the secondary side is connected together as a positive output end of the DC output of the rectifying and filtering unit; a DC negative output end of the rectifying and filtering unit is the common potential end; wherein the rectifying switch comprises a cathode and a high The diode connected to the secondary side of the frequency transformer (see Figure 2, Figure 5, Figure 9, and Figure 10) or the MOS tube (see Figure 13 and Figure 14).

In other cases in the present invention, the rectifying and filtering unit may be a bridge rectifying circuit whose input end is at both ends of the high frequency transformer, and the rectifying and filtering unit of the bridge rectifying circuit includes a diode (refer to FIG. 15). ) or a controlled MOS tube (see Figure 16). The rectifying and filtering unit may also be a full-wave rectifying circuit, and the rectifying and filtering unit of the full-wave rectifying circuit includes a diode (see FIGS. 17 and 19) or a controlled MOS tube (see FIGS. 18 and 20).

In any of the above cases, the rectifying and filtering unit further comprises a filtering module, wherein the filtering module comprises a filter inductor (L _f1 , L _f2 ) and a filter capacitor C _o ; wherein the filter inductor (L _f1 , L _f2 ) is connected in series with the DC The output capacitor and the negative terminal of the rectifier diode or the positive output of the bridge rectifier, the filter capacitor C _o is connected between the DC positive output terminal and the negative output terminal. It is worth mentioning that in bridge rectification, the above two filter inductors can also be combined into one.

11 to 20 show a derivative circuit of the rectifying and filtering unit in the present invention, that is, in any of the cases of the present invention, the rectifying and filtering unit can adopt any one of Figs. 11 to 20. A brief description of FIGS. 11 to 20 is as follows: The current doubler rectification circuit has two forms, and FIG. 2, FIG. 5, FIG. 9, FIG. 10, FIG. 12, and FIG. 13 are one of the circuit forms, and FIGS. 11 and 14 are Another circuit form; Fig. 2, Fig. 5, Fig. 9, Fig. 10, Fig. 11 and Fig. 12 are diode rectified, Fig. 13 and Fig. 14 are synchronous rectification; Fig. 15 is a diode rectified full bridge rectification circuit, Fig. 16 It is a full-bridge rectifier circuit using synchronous rectification; Figures 17 and 19 are full-wave rectification circuits using diode rectification, and Figures 18 and 20 are full-wave rectification circuits using synchronous rectification.

Further, Fig. 21 and Fig. 22 respectively show two kinds of deformed structures which may exist in the LC circuit in the rectifying and filtering unit of the present invention. In FIG. 21, an inductor that is usually connected in series with the filter capacitor is split into two and connected in series in the loop at both ends of the filter capacitor; and in FIG. 22, the inductor and the capacitor, which were originally one, are separately split. Two, each inductor and capacitor are connected in series, thus obtaining two separate LC filter circuits, the first LC filter circuit is connected between the output of the DC output and the ground, and the second LC filter circuit It is connected to both ends of the filter capacitor of the first LC filter circuit, and the load is connected to both ends of the filter capacitor of the second LC filter circuit. This will split the inductor or capacitor well. It is possible to reduce the inductance value or capacitance value of a single component, thereby reducing the volume of a single component, and being able to adapt to space or cost sensitive situations.

It is to be noted that, in the present invention, the respective units constituting the DC/DC converter in the above various cases, including the inverter unit, the rectifying and filtering unit, the resonating unit, and the rectifying and filtering unit, are not limited to the above description. A person skilled in the art can also make a reasonable combination, transformation or modification of the composition of each unit or the connection between the units according to common knowledge in the art.

The above-mentioned embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims

A DC/DC converter comprising an inverter unit, a resonance unit, a high frequency transformer and a rectification filtering unit; the inverter unit comprising a half bridge circuit in an asymmetric, complementary pulse width modulation control signal function a lower or full bridge circuit converts a DC input into a square wave under constant frequency phase shift control; the resonant unit obtains a square wave of its output by the inverter unit and resonates it, and transmits it to the high The primary side of the frequency transformer; the rectifying and filtering unit adopts double current rectification, full wave rectification or full bridge rectification and converts the alternating current waveform on the secondary side of the high frequency transformer into a direct current output by LC filtering.
The DC/DC converter according to claim 1, wherein the inverter unit comprises a half bridge circuit composed of a first controlled switch tube and a second controlled switch tube, and one end of the DC input passes through the first Two switch ends of one switch tube and two switch ends of the second switch tube are connected to the other end of the DC input; the two switch tubes are respectively input, asymmetric, complementary pulse width modulation signals Controlling a switch thereof; a pulse width of a control signal on a control end of the first switch tube determines a pulse width of the output square wave of the inverter unit; the resonance unit is configured by the first switch tube and the second switch tube The connection point and one or the other end of the DC input acquire a square wave output by the inverter unit.
The DC/DC converter according to claim 2, wherein a period of a control signal input from the control terminals of the first switching transistor and the second switching transistor is a set length, at the first controlled switch When the duty ratio of the control signal is D, the duty ratio of the control signal of the second controlled switch is 1-D; the two control signals are advanced or delayed by one at their adjacent high and low level switching positions, respectively. The width is set to form a dead zone of the set width to prevent the two switches from being turned on at the same time.
The DC/DC converter according to claim 1, wherein said inverter unit comprises a full bridge inverter circuit using constant frequency phase shift control; said full bridge inverter circuit comprises a first controlled switch a first half bridge circuit composed of a tube and a second controlled switch tube; and a second half bridge circuit composed of a third controlled switch tube and a fourth controlled switch tube; one end of the DC input sequentially passes through the first switch tube and The two switch ends of the two switch tubes are connected to the other end of the DC input; one end of the DC input is also followed by two of the third switch tube and the fourth switch tube The switch end is connected to the other end of the DC input; in the half bridge circuit, the two switch tubes are respectively controlled by the pulse width modulation signals input by the control terminals thereof and each having a 50% duty ratio and having a phase difference of 180 degrees; Having a set phase difference or phase shift angle between control signals of two controlled switches located at their topological diagonal positions in the two half bridge circuits, the set phase difference determining the inverter unit Outputting a pulse width of the square wave; the resonance unit obtains the output of the inverter unit by a connection point of the first switch tube and the second switch tube and a connection point of the third switch tube and the fourth switch tube wave.
The DC/DC converter according to claim 4, wherein in the first half bridge circuit and the second half bridge circuit, the pulse widths of the control signals of the two controlled switches in one half bridge circuit are equal Each having a 50% duty cycle and having a phase difference of 180 degrees, and the two control signals are advanced or delayed by a set width at their adjacent high and low level switching positions, respectively, forming a dead zone of a set width to prevent The two switching tubes are simultaneously turned on.
The DC/DC converter according to claim 1, wherein the resonance unit comprises a resonant inductor, a first resonant capacitor, and a second resonant capacitor, wherein the resonant inductor and the first resonant capacitor are connected in series with the high The primary side of the frequency transformer is connected in series on two terminals of the output square wave of the inverter unit, and the second resonant capacitor is connected to the primary or secondary side of the high frequency transformer or is the primary or secondary side. And the sum of the capacitors; the resonant inductor is the leakage inductance of the independent inductor or the transformer or the sum of the two; the second resonant capacitor is a separate capacitor or a parasitic capacitor of the rectifier switch or a parallel connection of the two, etc. Effective capacitance.
The DC/DC converter of claim 1 wherein said high frequency transformer has a primary side and one secondary side has one or more windings.
The DC/DC converter according to claim 7, wherein said rectifying and filtering circuit comprises a rectifying portion and a filtering portion; said rectifying portion comprises a rectifying device, wherein said rectifying device is used in a total current rectification The diode of the anode or common cathode current doubler rectifier circuit is a MOSFET adopting a synchronous rectifier circuit; the filtering part is an LC combined filter circuit.
The DC/DC converter according to claim 7, wherein said rectifying and filtering circuit includes a rectifying portion and a filtering portion; and said rectifying portion includes a rectifying device, In full-wave rectification, the rectifying device is a diode using a common anode or a common cathode rectifying circuit; and the filtering portion is an LC combined filter circuit.