阅读说明：本技术 一种功率转换电路及直流谐振转换器 (Power conversion circuit and direct current resonance converter ) 是由 朱阳阳 蒋劲松 赵凯洪 庄启超 郭水保 于 2020-04-13 设计创作，主要内容包括：本发明提供一种功率转换电路及直流谐振转换器,功率转换电路包括依次相连的三相桥模块、三相谐振模块、三相变压模块和整流模块,整流模块使用全波整流电路,并用含有反并联二极管的开关件代替二极管进行整流；所述三相桥模块还包括原边驱动单元以驱动所述三相桥交错通断谐振；整流模块还包括采样单元和门限比较单元,将每路采样电流信号与预设值比较后输出六路门限矩形波信号,以对应驱动所述整流模块中与采样回路相连的开关件的通断。在减小结构体积的同时,可以实现更宽的输入输出电压和更小的输出电流纹波。降低了开关损耗,提升了转换效率,降低了同步开关件的耐压,减少了所需的输出端滤波电容数量。(The invention provides a power conversion circuit and a direct current resonance converter, wherein the power conversion circuit comprises a three-phase bridge module, a three-phase resonance module, a three-phase transformation module and a rectification module which are sequentially connected, wherein the rectification module uses a full-wave rectification circuit and uses a switching element containing an anti-parallel diode to replace a diode for rectification; the three-phase bridge module also comprises a primary side driving unit for driving the three-phase bridge to perform staggered on-off resonance; the rectification module also comprises a sampling unit and a threshold comparison unit, and six threshold rectangular wave signals are output after each path of sampling current signal is compared with a preset value so as to correspondingly drive the on-off of a switch piece connected with the sampling loop in the rectification module. The structure volume is reduced, and meanwhile, wider input and output voltage and smaller output current ripple can be realized. The switching loss is reduced, the conversion efficiency is improved, the withstand voltage of the synchronous switching element is reduced, and the number of required output end filter capacitors is reduced.)

1. A power conversion circuit is characterized by comprising a three-phase bridge module, a three-phase resonance module, a three-phase transformation module and a rectification module which are sequentially connected, wherein the three-phase bridge module comprises three primary side half bridges, each primary side half bridge comprises two switching elements which are connected in series, the three-phase resonance module comprises a plurality of resonance units, the resonance units comprise resonance capacitors and resonance inductors which are connected in series, the transformation module comprises three transformers, the rectification module adopts a full-wave rectification circuit, and the diodes are replaced by the switching elements containing anti-parallel diodes for rectification;

the three-phase bridge module also comprises a primary side driving unit, and the primary side driving unit is connected with the control end of each switch element in each primary side half bridge so as to output a primary side driving signal to drive the switch elements in the three-phase bridge module to be switched on and off in a staggered manner;

the rectifying module further comprises a sampling unit and a threshold comparison unit, wherein the sampling unit samples the current of the in-phase end and the anti-phase end of each secondary transformer, and outputs six sampling current signals to the threshold comparison unit, and the threshold comparison unit is connected with the control end of each switch piece in the rectifying module and is used for comparing each sampling current signal with a preset value and then outputting six threshold rectangular wave signals so as to correspondingly drive the on-off of the switch piece connected with the sampling loop in the rectifying module.

2. The power conversion circuit of claim 1, wherein the three-phase bridge module comprises a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch, the three-phase resonant module comprises a first resonant inductor, a first resonant capacitor, a second resonant inductor, a second resonant capacitor, a third resonant inductor, and a third resonant capacitor, and the three-phase transformation module comprises a first transformer, a second transformer, and a third transformer; wherein:

the input end of the first switching element is connected with the output end of the second switching element to form a first primary side half bridge, the input end of the third switching element is connected with the output end of the fourth switching element to form a second primary side half bridge, the input end of the fifth switching element is connected with the output end of the sixth switching element to form a third primary side half bridge, the output ends of the first switching element, the third switching element and the fifth switching element are connected with the negative electrode of a primary side bus, and the input ends of the second switching element, the fourth switching element and the sixth switching element are connected with the positive electrode of the primary side bus;

the first end of the first resonant inductor is connected with the output end of the second switching element, the first end of the second resonant inductor is connected with the output end of the fourth switching element, the first end of the third resonant inductor is connected with the output end of the sixth switching element, the second end of the first resonant inductor is connected with the primary in-phase end of the first transformer through the first resonant capacitor, the second end of the second resonance inductor is connected with the primary in-phase end of the second transformer through the second resonance capacitor, the second end of the third resonant inductor is connected with the primary in-phase end of the third transformer through the third resonant capacitor, the primary inverting terminals of the first transformer, the second transformer and the third transformer are connected with each other, and the secondary sides of the first transformer, the second transformer and the third transformer are connected with the rectifying module.

3. The power conversion circuit of claim 2, wherein the switching frequencies of the first, second and third primary side half bridges are the same, and the switching timings of the first, third and fifth switching elements differ by 120 °.

4. The power conversion circuit according to claim 2, wherein the rectification module comprises a seventh switch tube, an eighth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube and a twelfth switch tube, the secondary in-phase terminal of the first transformer is connected to the output terminal of the seventh switch tube, the secondary inverting terminal of the first transformer is connected to the output terminal of the eighth switch tube, the secondary in-phase terminal of the second transformer is connected to the output terminal of the ninth switch tube, the secondary inverting terminal of the second transformer is connected to the output terminal of the tenth switch tube, the secondary in-phase terminal of the third transformer is connected to the output terminal of the eleventh switch tube, the secondary inverting terminal of the third transformer is connected to the output terminal of the twelfth switch tube, and the secondary center taps of the first transformer, the second transformer and the third transformer are all connected to the positive pole of the secondary side bus bar, and the input ends of the seventh switching tube, the eighth switching tube, the ninth switching tube, the tenth switching tube, the eleventh switching tube and the twelfth switching tube are all connected with the negative electrode of the secondary side bus.

5. The power conversion circuit according to claim 4, wherein the rectifier module further comprises a first logic unit, the first logic unit is connected to the primary side driving unit and is connected between the control terminals of the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch and the twelfth switch and the threshold comparison unit, and is configured to obtain the primary side driving signal and the threshold rectangular wave signal, and output a pulse width modulation signal after operation to correspondingly drive on/off of the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch and the twelfth switch.

6. The power conversion circuit of claim 5, wherein the rectification module further comprises an enable unit and a second logic unit, wherein:

the enabling unit is connected with the second logic unit and used for outputting an enabling switch signal to the second logic unit;

the second logic unit is connected between the control ends of the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch and the twelfth switch and the first logic unit, and is used for receiving the pulse width modulation signal and the enable switch signal, and outputting a rectification switch signal after operation so as to correspondingly drive the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch and the twelfth switch to be switched on and off.

7. The power conversion circuit according to claim 1, wherein the power conversion circuit further comprises a primary side filter capacitor and/or a secondary side filter capacitor, wherein the positive terminal of the primary side filter capacitor is connected to the positive terminal of the primary side bus, and the negative terminal of the primary side filter capacitor is connected to the negative terminal of the primary side bus; and/or the positive end of the secondary filter capacitor is connected with the positive electrode of the secondary bus, and the negative end of the secondary filter capacitor is connected with the negative electrode of the secondary bus.

8. The power conversion circuit of claim 1, wherein the switching timings of the two switching tubes in series in each primary side half bridge of the three-phase bridge module are different by 180 °.

9. The power conversion circuit of claim 1, wherein the switching element is an N-type MOS transistor.

10. A dc resonant converter comprising a power conversion circuit according to any of claims 1-9.

Technical Field

The invention relates to the technical field of power supplies, in particular to a power conversion circuit and a direct-current resonant converter.

Background

At present, a direct current-direct current converter with a wide input and output voltage range can realize that the circuit topology is more, such as a full-bridge hard switch circuit topology, a phase-shifted full-bridge topology, an active clamp forward and backward excitation topology and a full-bridge LLC topology are isolated, and secondary side rectification modes comprise rectification, bridge rectifier, current doubling rectification and the like.

The full-bridge LLC topology has the problems of large output ripple current, large stress of capacitor filtering current and the like, and the ZVS phase-shifted full-bridge and hard switch full-bridge current-doubling rectification can greatly reduce the ripple current stress; because the voltage-withstanding selection of the synchronous rectification MOS is affected by an excessively large input/output voltage range and transient voltage spike stress, the increase of efficiency is adversely affected by an excessively large on-resistance (especially, 100V or more) of the high-voltage MOS, and it is difficult to achieve a wider input/output voltage range.

The bridge stack synchronous rectification MOS tube has low voltage stress, but the rectification loss is relatively large due to the structure that the rectifiers are connected in series for rectification; the current-doubling rectification is the staggered rectification and has the advantage of smaller ripple current, but the double-inductor structure has relatively larger volume and is less in the type of primary side topology.

Disclosure of Invention

The invention aims to provide a power conversion circuit and a direct current resonant converter, which can realize wider input and output voltage, smaller output current ripple and smaller structural volume.

The invention provides a power conversion circuit, and particularly relates to a power conversion circuit which comprises a three-phase bridge module, a three-phase resonance module, a three-phase transformation module and a rectification module which are sequentially connected, wherein the three-phase bridge module comprises three primary half bridges, each primary half bridge comprises two switching elements which are connected in series, the three-phase resonance module comprises a plurality of resonance units, each resonance unit comprises a resonance capacitor and a resonance inductor which are connected in series, the transformation module comprises three transformers, the rectification module adopts a full-wave rectification circuit, and the diodes are replaced by the switching elements containing anti-parallel diodes for rectification; the three-phase bridge module also comprises a primary side driving unit, and the primary side driving unit is connected with the control end of each switch element in each primary side half bridge so as to output a primary side driving signal to drive the switch elements in the three-phase bridge module to be switched on and off in a staggered manner; the rectifying module further comprises a sampling unit and a threshold comparison unit, wherein the sampling unit samples the current of the in-phase end and the anti-phase end of each secondary transformer, and outputs six sampling current signals to the threshold comparison unit, and the threshold comparison unit is connected with the control end of each switch piece in the rectifying module and is used for comparing each sampling current signal with a preset value and then outputting six threshold rectangular wave signals so as to correspondingly drive the on-off of the switch piece connected with the sampling loop in the rectifying module.

Further, the three-phase bridge module comprises a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch, the three-phase resonance module comprises a first resonance inductor, a first resonance capacitor, a second resonance inductor, a second resonance capacitor, a third resonance inductor and a third resonance capacitor, and the three-phase transformation module comprises a first transformer, a second transformer and a third transformer; wherein: the input end of the first switching element is connected with the output end of the second switching element to form a first primary side half bridge, the input end of the third switching element is connected with the output end of the fourth switching element to form a second primary side half bridge, the input end of the fifth switching element is connected with the output end of the sixth switching element to form a third primary side half bridge, the output ends of the first switching element, the third switching element and the fifth switching element are connected with the negative electrode of a primary side bus, and the input ends of the second switching element, the fourth switching element and the sixth switching element are connected with the positive electrode of the primary side bus; the first end of the first resonant inductor is connected with the output end of the second switching element, the first end of the second resonant inductor is connected with the output end of the fourth switching element, the first end of the third resonant inductor is connected with the output end of the sixth switching element, the second end of the first resonant inductor is connected with the primary in-phase end of the first transformer through the first resonant capacitor, the second end of the second resonance inductor is connected with the primary in-phase end of the second transformer through the second resonance capacitor, the second end of the third resonant inductor is connected with the primary in-phase end of the third transformer through the third resonant capacitor, the primary inverting terminals of the first transformer, the second transformer and the third transformer are connected with each other, and the secondary sides of the first transformer, the second transformer and the third transformer are connected with the rectifying module.

Further, the switching frequencies of the first primary side half bridge, the second primary side half bridge and the third primary side half bridge are the same, and the switching time sequences of the first switching element, the third switching element and the fifth switching element are different by 120 °.

Further, the rectifier module includes a seventh switch tube, an eighth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube and a twelfth switch tube, a secondary in-phase end of the first transformer is connected to an output end of the seventh switch tube, a secondary inverting end of the first transformer is connected to an output end of the eighth switch tube, a secondary in-phase end of the second transformer is connected to an output end of the ninth switch tube, a secondary inverting end of the second transformer is connected to an output end of the tenth switch tube, a secondary in-phase end of the third transformer is connected to an output end of the eleventh switch tube, a secondary inverting end of the third transformer is connected to an output end of the twelfth switch tube, secondary center taps of the first transformer, the second transformer and the third transformer are all connected to an anode of the secondary side bus, the seventh switch tube, the ninth switch tube, the tenth switch tube, the eighth switch tube, the twelfth switch tube, the ninth switch tube, and the twelfth switch tube, The input ends of the eighth switching tube, the ninth switching tube, the tenth switching tube, the eleventh switching tube and the twelfth switching tube are connected with the negative electrode of the secondary side bus.

The rectifying module further includes a first logic unit, connected to the primary side driving unit, and connected between the control ends of the seventh, eighth, ninth, tenth, eleventh, and twelfth switching elements and the threshold comparing unit, and configured to obtain the primary side driving signal and the threshold rectangular wave signal, and output a pulse width modulation signal after operation to correspondingly drive on/off of the seventh, eighth, ninth, tenth, eleventh, and twelfth switching elements.

Furthermore, the rectifier module further comprises an enable unit and a second logic unit, wherein the enable unit is connected with the second logic unit and is used for outputting an enable switch signal to the second logic unit; the second logic unit is connected between the control ends of the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch and the twelfth switch and the first logic unit, and is used for receiving the pulse width modulation signal and the enable switch signal, and outputting a rectification switch signal after operation so as to correspondingly drive the seventh switch, the eighth switch, the ninth switch, the tenth switch, the eleventh switch and the twelfth switch to be switched on and off.

Furthermore, the power conversion circuit further comprises a primary side filter capacitor and/or a secondary side filter capacitor, wherein the positive electrode end of the primary side filter capacitor is connected with the positive electrode of the primary side bus, and the negative electrode end of the primary side filter capacitor is connected with the negative electrode of the primary side bus; and/or the positive end of the secondary filter capacitor is connected with the positive electrode of the secondary bus, and the negative end of the secondary filter capacitor is connected with the negative electrode of the secondary bus.

Further, in the three-phase bridge module, the switching time sequences of two switching tubes connected in series in each primary side half bridge are different by 180 °.

Further, the switch element is an N-type MOS tube.

Secondly, the invention also provides a direct current resonant converter, and particularly, the direct current resonant converter comprises any one of the power conversion circuits.

The power conversion circuit and the direct current resonant converter provided by the invention can realize wider input and output voltage and smaller output current ripple while reducing the structural size. The switching loss is reduced, the conversion efficiency is improved, the withstand voltage of the synchronous switching piece is reduced, the number of required output end filter capacitors is reduced, and the user experience is greatly improved.

Drawings

Fig. 1 is a block diagram of a power conversion circuit according to an embodiment of the invention.

Fig. 2 is a first circuit diagram of a power conversion circuit according to an embodiment of the invention.

Fig. 3 is a circuit diagram of a power conversion circuit according to a second embodiment of the invention.

Fig. 4 is a third circuit diagram of a power conversion circuit according to an embodiment of the invention.

Fig. 5 is a timing diagram of a primary side driving signal of a power conversion circuit according to an embodiment of the invention.

Fig. 6 is a fourth circuit diagram of the power conversion circuit according to the embodiment of the invention.

Fig. 7 is a first block diagram of a rectifier module according to an embodiment of the invention.

Fig. 8 is a timing diagram of a primary side driving signal, a sampling current signal and a threshold rectangular wave signal of a power conversion circuit according to an embodiment of the invention.

Fig. 9 is a block diagram of a rectifier module according to an embodiment of the invention.

Fig. 10 is a block diagram of a rectifier module according to an embodiment of the invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

In a first aspect, the present invention provides a power conversion circuit. Fig. 1 is a block diagram of a power conversion circuit according to an embodiment of the invention. As shown in fig. 1, the power conversion circuit includes a three-phase bridge module 1, a three-phase resonance module 2, a three-phase transformation module 3, and a rectification module 4, which are connected in sequence. The three-phase bridge module 1 further comprises a primary drive unit 11.

The direct current power supply voltage is input from a primary bus through the three-phase bridge module 1, under the drive of the primary driving unit 11, the alternating resonance of the three-phase resonance module 2 outputs the rectified direct current voltage through the primary-to-secondary voltage transformation of the three-phase voltage transformation module 3 and the rectification module 4, so that the direct current-direct current power conversion is realized.

Fig. 2 is a first circuit diagram of a power conversion circuit according to an embodiment of the invention.

As shown in fig. 2, in an embodiment, the three-phase bridge module 1 of the power conversion circuit includes a first switching device Q1, a second switching device Q2, a third switching device Q3, a fourth switching device Q4, a fifth switching device Q5 and a sixth switching device Q6. The three-phase resonant module 2 of the power conversion circuit includes a first resonant inductor L1, a first resonant capacitor C1, a second resonant inductor L2, a second resonant capacitor C2, a third resonant inductor L3, and a third resonant capacitor C3. The three-phase transformation module 3 of the power conversion circuit includes a first transformer T1, a second transformer T2, and a third transformer T3.

The input terminal of the first switching element Q1 is connected to the output terminal of the second switching element Q2 to form a first primary side half bridge. An input terminal of the third switching element Q3 is connected to an output terminal of the fourth switching element Q4 to form a second primary side half bridge. An input terminal of the fifth switching element Q5 is connected to an output terminal of the sixth switching element Q6 to form a third primary side half bridge. The outputs of the first, third and fifth switching devices Q1, Q3, Q5 are connected to the negative Vi + of the primary bus, and the inputs of the second, fourth and sixth switching devices Q2, Q4, Q6 are connected to the positive Vi + of the primary bus.

A first terminal of the first resonant inductor L1 is connected to the output terminal of the second switching device Q2, a first terminal of the second resonant inductor L2 is connected to the output terminal of the fourth switching device Q4, and a first terminal of the third resonant inductor L3 is connected to the output terminal of the sixth switching device Q6.

A second terminal of the first resonant inductor L1 is connected to the primary in-phase terminal of the first transformer T1 through a first resonant capacitor C1 to form a first resonant cell. A second terminal of the second resonant inductor L2 is connected to the primary in-phase terminal of the second transformer T2 through a second resonant capacitor C2 to form a second resonant cell. A second terminal of the third resonant inductor L3 is connected to the primary in-phase terminal of the third transformer T3 through a third resonant capacitor C3, forming a third resonant cell. The primary inverting terminals of the first, second and third transformers T1, T2 and T3 are connected to each other to form a resonant tank, so that the primary sides of the three transformers are star-connected.

The secondary sides of the first, second and third transformers T1, T2 and T3 are connected to the rectifying module 4 to output the converted voltage.

The three-phase bridge module 1 further comprises a primary drive unit 11. The primary side driving unit 11 is connected to control terminals of the first switching element Q1, the second switching element Q2, the third switching element Q3, the fourth switching element Q4, the fifth switching element Q5 and the sixth switching element Q6 to respectively output primary side driving signals to control the staggered switching of the first switching element Q1, the second switching element Q2, the third switching element Q3, the fourth switching element Q4, the fifth switching element Q5 and the sixth switching element Q6.

The rectifying module 4 may be a conventional rectifying circuit, such as a full-wave rectifying circuit, a half-wave rectifying circuit, a bridge rectifying circuit, or a voltage-doubling rectifying circuit.

Under the control of the original side driving signal that sends through original side drive unit 11, first original side half-bridge, the crisscross parallel work of second original side half-bridge and third original side half-bridge, after six switching elements of direct current original side generating line input three half-bridges of constituteing, become alternating voltage through three resonance unit resonance, and then through the three-phase alternating voltage after three transformer output vary voltage, through rectifier module 4's rectification, the effect of wider input output voltage and less output current ripple has been realized, conversion efficiency has been promoted simultaneously.

In one embodiment, in each resonant tank of the three-phase resonant module 2, the inductance of all resonant inductors is 17mH, and the capacitance of all resonant capacitors is 110 nF. In other embodiments, the inductance of the resonant inductor and the capacitance of the resonant capacitor may be selected according to the requirement of the resonant center frequency point. The conversion from three-phase direct-current voltage to three-phase alternating-current voltage is realized through the resonance function of the three-phase resonance module, so that the switching on and off of a soft switch can be realized by a switching piece in the primary three-phase bridge module, the overlapping of voltage and current in the switching process is eliminated, and the switching loss is greatly reduced. Meanwhile, the resonant process also limits the change rate of voltage and current in the switching process, so that the switching noise is reduced.

Fig. 3 is a circuit diagram of a power conversion circuit according to a second embodiment of the invention.

As shown in fig. 3, in an embodiment, the rectifying module 4 is a full-wave rectifying circuit including a seventh diode D7, an eighth diode D8, a ninth diode D9, a twelfth diode D10, an eleventh diode D11 and a twelfth diode D12. The in-phase terminal of the secondary side of the first transformer T1 is connected to the cathode of the seventh diode D7, and the inverted terminal of the secondary side of the first transformer T1 is connected to the cathode of the eighth diode D8. The non-inverting secondary terminal of the second transformer T2 is connected to the cathode of the ninth diode D9, and the inverting secondary terminal of the second transformer T2 is connected to the cathode of the twelfth diode D10. The non-inverting terminal of the secondary side of the third transformer T3 is connected to the cathode of the eleventh diode D11, and the inverting terminal of the secondary side of the third transformer T3 is connected to the cathode of the twelfth diode D12. The secondary center taps of the first, second and third transformers T1, T2 and T3 are connected to each other to be set as the anode Vo + of the secondary bus, and the anodes of the seventh, eighth, ninth, twelfth, eleventh and twelfth diodes D7, D8, D9, D10, D11 and D12 are all connected to each other to be set as the cathode Vo-of the secondary bus.

Through the full-wave rectification circuit formed by the six diodes, the output voltage ripple can be further reduced while the structure volume is reduced, the withstand voltage of an output end device is reduced, and the conversion efficiency is improved.

In another embodiment, on the basis of the above embodiment, the anodes and the cathodes of the seventh diode D7, the eighth diode D8, the ninth diode D9, the twelfth diode D10, the eleventh diode D11 and the twelfth diode D12 are connected in the opposite directions, so that the anode Vo + and the cathode Vo-of the output secondary bus are intermodulation.

Fig. 4 is a third circuit diagram of a power conversion circuit according to an embodiment of the invention.

As shown in fig. 4, in one embodiment, the power conversion circuit further includes a primary filter capacitor C4. The positive end of the primary side filter capacitor C4 is connected with the positive electrode Vi + of the primary side bus bar, and the negative end of the primary side filter capacitor C4 is connected with the negative electrode Vi-of the primary side bus bar.

And/or, as shown in fig. 4, the power conversion circuit further includes a secondary filter capacitor, the positive terminal of the secondary filter capacitor is connected to the positive electrode Vo + of the secondary bus, and the negative terminal of the secondary filter capacitor is connected to the negative electrode Vo-of the secondary bus.

The filter capacitor is an energy storage device, and is connected in parallel to the input end or the output end of the power conversion circuit, so that the ripple coefficient of voltage can be reduced, high-efficiency smooth direct current output is improved, and the ripple of output voltage is further reduced. The filter capacitor can be a conventional electrolytic capacitor or a ceramic capacitor and the like.

Taking the case of turning on the high-level driving switch as an example, fig. 5 is a timing diagram of the primary side driving signal of the power conversion circuit according to an embodiment of the invention. Among the primary side driving signals, the primary side driving signal of the first switching element Q1 is a first primary side driving signal S1, the primary side driving signal of the second switching element Q2 is a second primary side driving signal S2, the primary side driving signal of the third switching element Q3 is a third primary side driving signal S3, the primary side driving signal of the fourth switching element Q4 is a fourth primary side driving signal S4, the primary side driving signal of the fifth switching element Q5 is a fifth primary side driving signal S5, and the primary side driving signal of the sixth switching element Q6 is a sixth primary side driving signal S6.

In one embodiment, as shown in fig. 5, in the primary side driving signals, the primary side driving signals of the first switching element Q1 and the second switching element Q2 are opposite in phase, the primary side driving signals of the third switching element Q3 and the fourth switching element Q4 are opposite in phase, and the primary side driving signals of the fifth switching element Q6 and the sixth switching element Q6 are opposite in phase. In one embodiment, the high-level duty cycles of the primary side driving signals of the first switching device Q1, the second switching device Q2, the third switching device Q3, the fourth switching device Q4, the fifth switching device Q5 and the sixth switching device Q6 are all fifty percent. In another embodiment, due to the switching characteristics of the MOS transistors, in order to protect the MOS transistors, the high-level duty ratios of the primary side driving signals of the first switching device Q1, the second switching device Q2, the third switching device Q3, the fourth switching device Q4, the fifth switching device Q5 and the sixth switching device Q6 are slightly lower than fifty percent.

As shown in fig. 5, in one embodiment, the switching frequencies of the first, second and third primary half-bridges are the same. The switching timings of the first switching device Q1, the third switching device Q3 and the fifth switching device Q5 are different by 120 ° under the driving of the primary side driving signal.

In the using embodiment of the circuit, the gain of the power conversion circuit can be adjusted by adjusting the frequency of the primary side driving signal, so that the power conversion circuit is suitable for more using scenes. In other embodiments, the gain may also be adjusted by adjusting the duty cycle.

Fig. 6 is a fourth circuit diagram of the power conversion circuit according to the embodiment of the invention.

As shown in fig. 6, in an embodiment, the power conversion circuit further includes a seventh switching device Q7, an eighth switching device Q8, a ninth switching device Q9, a tenth switching device Q10, an eleventh switching device Q11, and a twelfth switching device Q12. The seventh switching device Q7 is connected in anti-parallel with the seventh diode D7, the eighth switching device Q8 is connected in anti-parallel with the eighth diode D8, the ninth switching device Q9 is connected in anti-parallel with the ninth diode D9, the tenth switching device Q10 is connected in anti-parallel with the twelfth diode D10, the eleventh switching device Q11 is connected in anti-parallel with the eleventh switching device Q11, and the twelfth switching device Q12 is connected in anti-parallel with the twelfth diode D12.

Because the secondary side uses the switch element for full-wave alternating current rectification, the on-off control of the soft switch can be realized, the overlapping of voltage and current in the switching process is eliminated, the switching loss is greatly reduced, and the switching noise is also reduced. Because the primary three-phase bridge module is controlled in a three-phase staggered mode, current ripples can be reduced, and the capacity requirements of primary and secondary filter capacitors are reduced. The voltage stress of the secondary side rectification switch part is also reduced, the rectification loss is reduced, a wider input and output voltage range can be realized, and the size and the cost of the power change device are reduced.

In one embodiment, the rectification module 4 performs full-wave rectification by using a switching device such as a MOS transistor including an anti-parallel diode instead of a diode. Since some of the switching devices have parasitic antiparallel diodes, such as MOS transistors having antiparallel diodes, in the wafer, the switching device and the antiparallel diode are actually one MOS transistor.

In an embodiment, the seventh switching device Q7, the eighth switching device Q8, the ninth switching device Q9, the tenth switching device Q10, the eleventh switching device Q11 and the twelfth switching device Q12 are all high-level conducting switching devices.

In an embodiment, control terminals of the seventh switching element Q7, the eighth switching element Q8, the ninth switching element Q9, the tenth switching element Q10, the eleventh switching element Q11 and the twelfth switching element Q12 are respectively connected to the primary side driving unit 11, the seventh switching element Q7 is switched on and off synchronously with the first switching element Q1, the eighth switching element Q8 is switched on and off synchronously with the second switching element Q2, the ninth switching element Q9 is switched on and off synchronously with the third switching element Q3, the tenth switching element Q10 is switched on and off synchronously with the fourth switching element Q4, the eleventh switching element Q11 is switched on and off synchronously with the fifth switching element Q5, and the twelfth switching element Q12 is switched on and off synchronously with the sixth switching element Q6. In other embodiments, the control terminals of the seventh switching device Q7, the eighth switching device Q8, the ninth switching device Q9, the tenth switching device Q10, the eleventh switching device Q11 and the twelfth switching device Q12 are not connected to the primary side driving unit 11, and the rectification module 4 generates the control signals to switch the seventh switching device Q7, the eighth switching device Q8, the ninth switching device Q9, the tenth switching device Q10, the eleventh switching device Q11 and the twelfth switching device Q12 in other manners.

In one embodiment, before the secondary side switching element is turned on, due to the presence of the anti-parallel diode in the switching element, when a resonant voltage is applied across the switching tube, the anti-parallel diode is preferentially turned on, thereby generating a resonant current at the secondary side.

Fig. 7 is a first block diagram of a rectifier module according to an embodiment of the invention.

In an embodiment, as shown in fig. 7, the rectifying module 4 further includes a sampling unit 41 and a threshold comparing unit 42. The sampling unit 41 respectively samples the currents at the secondary in-phase terminal of the first transformer T1, the secondary inverting terminal of the first transformer T1, the secondary in-phase terminal of the second transformer T2, the secondary inverting terminal of the second transformer T2, the secondary in-phase terminal of the third transformer T3, and the secondary inverting terminal of the third transformer T3. The threshold comparing unit 42 is connected to the sampling unit 41, and is configured to obtain six sampling current signals sampled by the sampling unit 41, compare each sampling current signal with a preset value, and output six threshold rectangular wave signals to the control terminals of the seventh switching element Q7, the eighth switching element Q8, the ninth switching element Q9, the tenth switching element Q10, the eleventh switching element Q11, and the twelfth switching element Q12, so as to drive the switching elements to be turned on and off.

Due to the ac current sampling, the sampling unit 41 in the circuit may adopt various conventional sampling methods, such as resistance sampling, current transformer sampling, and hall element sampling. In an embodiment, the sampling unit 41 adopts six current sampling devices of a resistance sampling method, which are respectively connected in series between the secondary in-phase terminal of the first transformer T1 and the cathode of the seventh diode D7, between the secondary inverting terminal of the first transformer T1 and the cathode of the eighth diode D8, between the secondary in-phase terminal of the second transformer T2 and the cathode of the ninth diode D9, between the secondary inverting terminal of the second transformer T2 and the cathode of the twelfth diode D10, between the secondary in-phase terminal of the third transformer T3 and the cathode of the eleventh diode D11, and between the secondary inverting terminal of the third transformer T3 and the cathode of the twelfth diode D12, so as to respectively sample six sampling current signals.

In one embodiment, the threshold comparison unit 42 is implemented with a Digital Signal Processor (DSP) chip.

On the secondary side of the threshold comparison unit 42, a fixed value, i.e. a preset value, is selected as the turn-on threshold of the secondary side switching element. Taking the first transformer secondary as an example: the sampling unit 41 converts the current sampled at the non-inverting terminal of the second side of the first transformer T1 into a voltage to be compared with a predetermined value by the threshold comparing unit 42. When the sampling current signal is greater than the turn-on threshold, the threshold comparing unit 42 outputs the threshold rectangular wave signal of the seventh switching device Q7 as a high level, turning on the seventh switching device Q7. When the sampled current signal is not greater than the turn-on threshold, the threshold comparing unit 42 outputs the threshold rectangular wave signal of the seventh switching device Q7 as a low level, turning off the seventh switching device Q7. The sampling unit 41 converts the current sampled at the inverting terminal of the secondary side of the first transformer T1 into a voltage to be compared with a preset value by the threshold comparison unit 42. When the sampled current signal is greater than the turn-on threshold, the threshold comparing unit 42 outputs the threshold rectangular wave signal of the eighth switching element Q8 as a high level, turning on the eighth switching element Q8. When the sampled current signal is not greater than the turn-on threshold, the threshold comparing unit 42 outputs the threshold rectangular wave signal of the eighth switching element Q8 as a low level, turning off the eighth switching element Q8. The on-off of other switch elements on the secondary side is the same as the principle, and the description is omitted.

Fig. 8 is a timing diagram of a primary side driving signal, a sampling current signal and a threshold rectangular wave signal of a power conversion circuit according to an embodiment of the invention.

As shown in fig. 8, the current I1 at the non-inverting terminal of the secondary side of the first transformer T1 is sampled, and a seventh rectangular wave signal M1 is generated through the threshold comparing unit 42 to drive the seventh switching device Q7 to be turned on and off. The current I8 at the secondary inverting terminal of the first transformer T1 is sampled, and an eighth rectangular wave signal M8 is generated through the threshold comparing unit 42 to drive the eighth switching device Q8 to be turned on and off. The current I9 at the non-inverting terminal of the secondary side of the second transformer T2 is sampled, and a ninth rectangular wave signal M9 is generated through the threshold comparing unit 42 to drive the ninth switching device Q9 to be turned on and off. The current I10 at the secondary inverting terminal of the second transformer T2 is sampled, and a tenth rectangular wave signal M10 is generated through the threshold comparing unit 42 to drive the tenth switching device Q10 to be turned on and off. The current I11 at the non-inverting terminal of the secondary side of the third transformer T3 is sampled, and an eleventh rectangular wave signal M11 is generated through the threshold comparison unit 42 to drive the eleventh switch Q11 to be turned on and off. The current I12 at the secondary inverting terminal of the third transformer T3 is sampled, and a twelfth rectangular wave signal M12 is generated through the threshold comparison unit 42 to drive the twelfth switching device Q12 to be turned on and off.

The current of the in-phase end and the anti-phase end of each secondary of the transformer is sampled to generate rectangular wave signals to drive the switch tubes connected on the corresponding paths, so that the working characteristic deviation of the diodes under the large current can be avoided.

Fig. 9 is a block diagram of a rectifier module according to an embodiment of the invention.

As shown in fig. 9, in an embodiment, the rectifying module 4 further comprises a first logic unit 43. The first logic unit 43 is connected to the primary side driving unit 11, and is connected between the control terminals of the seventh switching device Q7, the eighth switching device Q8, the ninth switching device Q9, the tenth switching device Q10, the eleventh switching device Q11 and the twelfth switching device Q12 and the threshold comparing unit 42, for obtaining the primary side driving signal and the threshold rectangular wave signal, and outputting the pulse width modulation signal to the control terminals of the seventh switching device Q7, the eighth switching device Q8, the ninth switching device Q9, the tenth switching device Q10, the eleventh switching device Q11 and the twelfth switching device Q12.

In one embodiment, the first logic unit 43 is an and operation in a digital signal processing chip.

In an embodiment, the first logic unit 43 receives the primary side driving signal of the primary side switching element and the threshold rectangular wave signal of the secondary side switching element with the same resonant phase, and the primary side driving signal and the threshold rectangular wave signal are subjected to the operation and then used as the control signals of the corresponding switching tubes, so that the switching elements are ensured to be turned on when the switching elements in the primary side three-phase bridge module 1 of the power conversion circuit are turned on, and the false action caused by the interference current is prevented, so as to ensure that the secondary side switching element works in the correct state.

In one embodiment, the truth table for the first logic unit 43 is as follows:

in the synchronous rectification control of the above embodiment, the threshold comparison of the sampling current is performed by using the preset value, which is equivalent to sending out a control signal after delaying the zero-crossing signal, thereby achieving the purpose of controlling the rectification switching element to be conducted in a delayed manner. In practice, the primary side in the active control of power conversion drives the switching tube, corresponding delay conduction control is also implemented, and the delay conduction control of the rectification switching tube is further ensured through AND operation.

Fig. 10 is a block diagram of a rectifier module according to an embodiment of the invention.

As shown in fig. 10, in an embodiment, the rectifier module 4 further includes an enable unit 44 and a second logic unit 45, and the enable unit 44 is connected to the second logic unit 45 and is configured to output an enable switch signal to the second logic unit 45. The second logic unit 45 is connected between the control terminals of the seventh, eighth, ninth, tenth, eleventh, and twelfth switching devices Q7, Q8, Q9, Q10, Q11, and Q12 and the first logic unit 43, and is configured to receive the pulse width modulation signal and the enable switching signal and output a rectification switching signal to the control terminals of the seventh, eighth, ninth, tenth, eleventh, and twelfth switching devices Q7, Q8, Q9, Q10, Q11, and Q12.

In one embodiment, the second logic unit 45 is an and operation in a digital signal processing chip. . By adding the enabling unit 44, the enabling switching signal and the pulse width modulation signal are subjected to and operation and then used as the control signal of the secondary switching element, so that the protection of the circuit can be enhanced, and the secondary switching element can be correctly conducted under the condition that the enabling switching signal is effective, so that synchronous rectification is realized.

In one embodiment, the truth table for the operation of the second logic unit 45 is as follows:

it should be noted that in other embodiments, the switching device may be various switching devices or switching circuits. For example, the switch device may be an N-type MOS transistor, a P-type MOS transistor, or other types of switch devices such as a relay, a thyristor, and an IGBT. When the switching elements are different, the driving level is correspondingly adjusted.

In a second aspect, the invention also provides a dc resonant converter, in particular, a dc resonant converter including any one of the power conversion circuits as above. The implementation principle of the dc resonant converter is the same as that of the above embodiments, and is not described herein.

The power conversion circuit and the direct current resonant converter provided by the invention can realize wider input and output voltage and smaller output current ripple while reducing the structural size. The switching loss is reduced, the conversion efficiency is improved, the withstand voltage of the synchronous switching piece is reduced, the number of required output end filter capacitors is reduced, and the user experience is greatly improved.

In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. It will be understood that when an element such as a layer, region or substrate is referred to as being "formed on," "disposed on" or "located on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly formed on" or "directly disposed on" another element, there are no intervening elements present.

In this document, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms can be understood in a specific case to those of ordinary skill in the art.

As used herein, the ordinal adjectives "first", "second", etc., used to describe an element are merely to distinguish between similar elements and do not imply that the elements so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

As used herein, the meaning of "a plurality" or "a plurality" is two or more unless otherwise specified.

It will be understood by those skilled in the art that all or part of the steps of implementing the above method embodiments may be implemented by hardware associated with program instructions, and the program may be stored in a computer readable storage medium, and when executed, performs the steps including the above method embodiments. The foregoing storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, including not only those elements listed, but also other elements not expressly listed.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present disclosure, and all such changes or substitutions are included in the scope of the present disclosure. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.