CN102638167A - Parallel resonant converter circuit - Google Patents

Abstract

The invention provides a parallel resonant converter circuit which comprises at least two resonant converters running in an interleaving parallel mode. As the input end of each resonant converter is connected with an independent power supply terminal respectively, the power balance between the resonant converters can be realized through regulating the voltage connected with each resonant converter respectively, however, the power balance between the resonant converters is realized through regulating working frequencies in the prior art. Thus, the circuit provided by the invention can continuously have the interleaving parallel advantage of the resonant converters, can enable the ACs (Alternating Currents) on the output filter capacitors of the resonant converters to neutralize each other so as to reduce the power loss, and can achieve the power balance between the resonant converters.

Description

A Parallel Resonant Converter Circuit

technical field

The invention relates to the technical field of power electronic conversion, in particular to a parallel resonant converter circuit.

Background technique

Referring to FIG. 1 , this figure is a schematic diagram of a resonant converter circuit in the prior art.

The resonant converter includes a first switching tube S1, a second switching tube S2, a resonant capacitor Cr, a resonant inductor Lr, a transformer T, a first diode D1, a second diode D2, a filter capacitor Co and a load resistor Ro.

The first switching tube S1 and the second switching tube S2 are connected in series to both ends of the input voltage Vin, and the common end of the first switching tube S1 and the second switching tube S2 is connected to the transformer T through the series resonant capacitor Cr and the resonant inductance Lr. One end of the primary winding and the other end of the primary winding of the transformer T are grounded. One end of the secondary winding of the transformer T is connected to one end of the load resistor Ro through the first diode D1; the other end of the secondary winding is connected to the other end of the load resistor Ro through the second diode D2; the center tap of the secondary winding is connected to The other end of the load resistor Ro; the filter capacitor Co is connected in parallel to both ends of the load resistor Ro.

However, there are some disadvantages in the resonant converter. The higher AC current on the output filter capacitor Co produces greater power loss. In order to further reduce the AC current on the output filter capacitor, the resonant converter is generally controlled by interleaved parallel connection. Interleaved parallel connection means that at least two resonant converters operate at the same frequency with a certain phase-out angle. When multiple resonant converters are interleaved and operated in parallel, usually the input ends of the resonant converters are connected in parallel, and the output ends are connected in parallel to the same output filter capacitor. The AC currents on the output filter capacitors cancel each other out, so the AC current on the output filter capacitors can be reduced, thereby reducing power loss.

Because the power balance needs to be realized by adjusting the output voltage and output current of the resonant converter. The adjustment of the output voltage and output current of the resonant converter needs to be realized by adjusting the operating frequency of the resonant converter. If the interleaved parallel resonant converters operate at different operating frequencies, the advantages of the interleaved parallel connection will be lost. Therefore, it is difficult to realize the power balance among the resonant converters in the prior art when multiple resonant converters are interleaved and connected in parallel.

Contents of the invention

The technical problem to be solved by the present invention is to provide a parallel resonant converter circuit, which can not only reduce the AC current on the output filter capacitor, thereby reducing power loss, but also realize the power balance among the interleaved parallel resonant converters .

The present invention provides a parallel resonant converter circuit, comprising at least two resonant converters operating in an interleaved parallel mode, the output terminals of all the resonant converters are connected in parallel; the input terminals of each resonant converter are independently connected to different power sources end.

Preferably, the different power supply terminals are multiple independent DC sources;

The number of the DC sources is the same as the number of the resonant converters, and the input end of each resonant converter is connected to a DC source.

Preferably, the different power supply terminals are the output terminals of the previous stage circuit.

Preferably, an output filter capacitor is also included;

The output terminals of all the resonant converters include a first output terminal and a second output terminal, and the first output terminals and the second output terminals of all the resonant converters are respectively connected to both ends of the output filter capacitor.

Preferably, the resonant converter is an LLC resonant converter.

Preferably, when the number of the resonant converters is an even number, the out-of-phase angle of each resonant converter is 180/N degrees when the resonant converters are interleaved and connected in parallel; when the number of the resonant converters is an odd number, each resonant converter When the converters are interleaved and connected in parallel, the phase error angle is (2*180)/N degrees; said N is the number of resonant converters.

Preferably, when there are two resonant converters operating in the interleaved parallel mode, they are respectively the first resonant converter and the second resonant converter;

the output terminal of the first resonant converter and the output terminal of the second resonant converter are connected in parallel;

The input terminal of the first resonant converter and the input terminal of the second resonant converter are independently connected to different power supply terminals.

Preferably, the power supply terminals are a first DC source and a second DC source;

An input end of the first resonant converter is connected to a first direct current source; an input end of the second resonant converter is connected to a second direct current source.

Preferably, the first resonant converter and the second resonant converter operate 90 degrees out of phase.

Compared with the prior art, the present invention has the following advantages:

The parallel resonant converter circuit provided by the present invention includes at least two resonant converters operating in an interleaved parallel mode. Since the input terminals of each resonant converter are respectively connected to independent power supply terminals, the power balance among the various resonant converters can be realized by separately adjusting the voltage connected to each resonant converter. It is not necessary to adjust the operating frequency in order to realize the power balance among the various resonant converters as in the prior art. Therefore, the circuit provided by the present invention can continue to maintain the advantages of interleaved parallel connection of resonant converters, so that the alternating currents of each resonant converter on the output filter capacitor can cancel each other, reduce power loss, and realize the power between each resonant converter. balance.

Description of drawings

FIG. 1 is a schematic diagram of a resonant converter circuit in the prior art;

FIG. 2 is a structural diagram of Embodiment 1 of a parallel resonant converter circuit provided by the present invention;

3 is a structural diagram of Embodiment 2 of the parallel resonant converter circuit provided by the present invention;

Fig. 4 is a structure diagram of the third embodiment of the parallel resonant converter circuit provided by the present invention;

Fig. 5 is the current waveform diagram corresponding to Fig. 4 of the present invention;

Fig. 6 is a topological circuit diagram of another resonant converter provided by the present invention;

Fig. 7 is a topological circuit diagram of another resonant converter provided by the present invention;

FIG. 8 is a structural diagram of Embodiment 4 of the parallel resonant converter circuit provided by the present invention;

FIG. 9 is a structural diagram of Embodiment 5 of the parallel resonant converter circuit provided by the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.

Referring to FIG. 2 , this figure is a structure diagram of Embodiment 1 of a parallel resonant converter circuit provided by the present invention.

The parallel resonant converter circuit provided by the embodiment of the present invention includes at least two resonant converters operating in an interleaved parallel mode, the output terminals of all the resonant converters are connected in parallel; the input terminals of each resonant converter are independently connected to different power terminal.

As shown in FIG. 2 , the parallel resonant converter circuit includes N resonant converters, which are respectively the first resonant converter, the second resonant converter, and up to the Nth resonant converter.

It can be seen from Fig. 2 that the output ends of each resonant converter are connected in parallel, and its output voltage is Vo.

The output terminals of the parallel resonant converter provided by the embodiment of the present invention are connected in parallel, and the input terminals are independent. The power grounds connected to the input terminals of each parallel resonant converter may be independent DC sources, or may be independent output terminals of the previous stage circuit.

In the following, it is introduced that each input terminal is connected to an independent DC source as an example.

The number of the DC sources is the same as the number of the resonant converters, and the input end of each resonant converter is connected to a DC source. As shown in FIG. 2 , N resonant converters correspond to N independent DC sources, namely the first DC source Vin1 , the second DC source Vin2 , and up to the nth DC source Vinn. The input end of the first resonant converter is connected to the first DC source Vin1, the input end of the second resonant converter is connected to the second DC source Vin2, and the input end of the Nth resonant converter is connected to the nth DC source Vinn.

The parallel resonant converter circuit provided by the embodiment of the present invention further includes an output filter capacitor Vo;

The output terminals of all the resonant converters include a first output terminal and a second output terminal, and the first output terminals and the second output terminals of all the resonant converters are respectively connected to both ends of the output filter capacitor Vo.

All said resonant converters operate at the same frequency.

All said resonant converters operate in interleaved parallel mode.

In the following, the parallel connection of two resonant converters is taken as an example for introduction. Referring to FIG. 3 , this figure is a structural diagram of Embodiment 2 of the parallel resonant converter provided by the present invention.

The input end of the first resonant converter is connected to the first DC source Vin1; the input end of the second resonant converter is connected to the second DC source Vin2.

Iin1 and Iin2 represent input currents of the first resonant converter and the second resonant converter, respectively, and Io1 and Io2 represent output currents of the first resonant converter and the second resonant converter, respectively.

Assuming that M1 and M2 represent the DC voltage gains of the first resonant converter and the second resonant converter respectively, then M1=Vo/Vin1, M2=Vo/Vin2. Therefore, according to the law of energy conservation, in the steady state of the circuit, Io1=Iin1/M1, Io2=Iin2/M2. Assuming Io1=Io2, then Vin2/Vin1=M1/M2=Iin1/Iin2.

Assuming that the first resonant converter and the second resonant converter have the same design parameters, at the same operating frequency, the two resonant converters may have different DC voltage gains M1, M2 due to differences in actual device parameters. Since the first DC source and the second DC source are independent, different Vin1 and Vin2 can be set according to Vin2/Vin1=M1/M2 to achieve power balance between the first resonant converter and the second resonant converter .

In summary, the parallel resonant converter circuit provided by the present invention includes a plurality of resonant converters operating in an interleaved parallel mode. Since the input terminals of each resonant converter are respectively connected to independent power supply terminals, the power balance among the various resonant converters can be realized by separately adjusting the power supply connected to each resonant converter. It is not necessary to adjust the operating frequency in order to realize the power balance among the various resonant converters as in the prior art. Therefore, the circuit provided by the present invention can continue to maintain the advantages of interleaved parallel connection of resonant converters, so that the alternating currents of each resonant converter on the output filter capacitor can cancel each other, and realize the power balance between each resonant converter.

When a plurality of resonant converters provided by the present invention operate in interleaved parallel connection, when the number of said resonant converters is an even number, the phase error angle of each resonant converter when interleaved and parallel operated is 180/N degrees; when the resonant converter When the number of converters is an odd number, the out-of-phase angle of each resonant converter when they are interleaved and connected in parallel is (2*180)/N degrees; said N is the number of resonant converters.

The following takes the resonant converter as an LLC resonant converter as an example for introduction.

Refer to FIG. 4 , which is a structure diagram of Embodiment 3 of the parallel resonant converter circuit provided by the present invention.

As shown in Figure 4, the first resonant converter includes a first switch tube S1, a second switch tube S2, a first resonant capacitor Cr1, a first resonant inductor Lr1, a first excitation inductor Lm1, a first transformer T1, a first two Diode D1 and second diode D2.

The positive terminal of the first direct current source Vin1 is connected to the negative terminal of the first direct current source Vin1 through the first switch transistor S1 and the second switch transistor S2 in sequence.

The common terminal of the first switching tube S1 and the second switching tube S2 is connected to the negative terminal of the first DC source Vin1 through the first resonant capacitor Cr1, the first resonant inductance Lr1, and the first magnetizing inductance Lm1 in sequence.

The first end of the secondary winding of the first transformer T1 is connected to the first end of the output filter capacitor Co through the first diode D1, and the second end of the secondary winding of the first transformer T1 is connected to the output through the second diode D2 The first end of the filter capacitor Co, the center tap of the secondary winding of the first transformer T1 is connected to the second end of the output filter capacitor Co.

The second resonant converter includes a third switching tube S3, a fourth switching tube S4, a second resonant capacitor Cr2, a second resonant inductor Lr2, a second exciting inductor Lm2, a second transformer T2, a third diode D3 and a fourth Diode D4.

The positive terminal of the second direct current source Vin2 is connected to the negative terminal of the second direct current source Vin2 through the third switch tube S3 and the fourth switch tube S4 in sequence.

The common terminal of the third switching tube S3 and the fourth switching tube S4 is sequentially connected to the negative terminal of the second DC source Vin2 through the second resonant capacitor Cr2, the second resonant inductance Lr2 and the second magnetizing inductance Lm2.

The first end of the secondary winding of the second transformer T2 is connected to the first end of the output filter capacitor Co through the third diode D3, and the second end of the secondary winding of the second transformer T2 is connected to the output through the fourth diode D4 The first terminal of the filter capacitor Co and the center tap of the secondary winding of the second transformer T2 are connected to the second terminal of the output filter capacitor Co.

It should be noted that the first magnetizing inductance Lm1 and the second magnetizing inductance Lm2 may be the magnetizing inductance of the transformer itself, or may be additionally connected in parallel with the primary winding of the transformer.

Io1 is the output current of the first resonant converter, and Io2 is the output current of the second resonant converter.

Vo is the output voltage of the two resonant converters.

It should be noted that, preferably, the first resonant converter and the second resonant converter operate with a phase difference of 90 degrees.

Refer to FIG. 5 , which is a current waveform diagram corresponding to FIG. 4 .

It can be clearly seen from FIG. 5 that the current Io1+Io2 on the output filter capacitor Co is smaller than Io1 alone, and is also smaller than Io2 alone. In this way, the purpose of offsetting the two alternating currents is achieved on the output filter capacitor Co, which can reduce the power loss caused by the alternating current.

The resonant circuit in the resonant converter in the embodiment shown in FIG. 4 is a kind of LLC resonant circuit, and several other LLC resonant circuits will be introduced below.

It can be understood that the resonant circuit in the prior art shown in FIG. 1 is also a type of LLC resonant circuit.

Referring to FIG. 6 , this figure is a topological circuit diagram of another resonant converter provided by the present invention.

The LLC resonant circuit in this circuit includes a resonant inductance Lr and a resonant capacitor Cr connected to the primary winding of the transformer T. The output end of the secondary winding of the transformer T is also connected to a filter inductor Lo.

Referring to FIG. 7 , this figure is a topological circuit diagram of another resonant converter provided by the present invention.

It can be understood that the topological circuits of the single resonant converter shown in FIG. 1 , FIG. 6 and FIG. 7 can all be applied in multiple parallel-connected resonant converters shown in FIG. 2 .

In the above embodiments, the power supply terminal of the parallel resonant converter is used as an independent DC source as an example for introduction, and the following description is made by taking the power supply terminal of the parallel resonant converter as an independent output terminal of the previous stage circuit as an example.

Refer to FIG. 8 , which is a structure diagram of Embodiment 4 of the parallel resonant converter circuit provided by the present invention.

Each resonant converter in the parallel resonant converter circuit in Fig. 8 is introduced by taking the LLC resonant converter shown in Fig. 7 as an example.

The parallel resonant converter circuit in Figure 8 is introduced by taking two parallel resonant converters as an example. It can be seen from Figure 8 that the input terminals of the two parallel resonant converters are independent, and are respectively connected to the output terminals of the previous stage circuit; The output terminals of the two parallel resonant converters are connected in parallel at both ends of the output filter capacitor Co.

For the convenience of introduction, the previous stage circuit of each resonant converter is called the input module, the previous stage circuit of the first resonant converter is the first input module, and the previous stage circuit of the second resonant converter is the second input module. module.

The input module in this embodiment is a Boost circuit. It can be understood that the input module is not limited to the Boost circuit, and may also be a Buck circuit or any kind of PFC circuit. As long as the input module can be used as a power source for the resonant converter. The input module can be an AC/DC circuit or a DC/DC circuit. In this embodiment, the input module is an AC/DC circuit as an example for introduction.

It can be seen from FIG. 8 that the first input module includes a first diode D1, a second diode D2, a first switch S1, a second switch S2, and a first filter capacitor Cin1.

Among them, the first diode D1, the second diode D2, the first switching tube S1 and the second switching tube S2 form a full bridge circuit, and the first bridge arm is composed of the first diode D1 and the first switching tube S1 , on the second bridge arm are the second diode D2 and the second switch tube S2.

The second input module includes a fifth diode D5, a sixth diode D6, a fifth switch S5, a sixth switch S6 and a second filter capacitor Cin2.

Among them, the fifth diode D5, the sixth diode D6, the fifth switch tube S5, and the sixth switch tube S6 form a full bridge circuit, and the fifth diode D5 and the fifth switch tube S5 are on the first bridge arm. , on the second bridge arm are the sixth diode D6 and the sixth switch tube S6.

After the first input module and the second input module are connected in series with the inductor Lb, Vac is used as the power supply.

In addition, the parallel resonant converter circuit in this embodiment further includes a control circuit for detecting the output current of each resonant converter, and adjusting the output voltage of the input module according to the output current, so that each resonant converter has the same Output current, same output power, realizes power balance among parallel resonant converters.

Specifically, the control circuit can control the output voltage of the input module by controlling the on and off states of the switch tube in each input module.

It can be seen from FIG. 8 that the first input module and the second input module are connected in series. It can be understood that the first input module and the second input module can also be connected in parallel. As shown in FIG. 9, the first input module and the second input module are respectively connected in parallel to the power supply Vac The other structures in FIG. 9 are the same as those in FIG. 8 , and will not be repeated here. The input ends of each resonant converter in the parallel resonant converter circuit provided by the embodiment of the present invention are independent, so each resonant converter has a characteristic of automatically balancing power, which can be connected by adjusting the input end of each resonant converter power supply to achieve power balance.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent of equivalent change Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. a parallel resonance converter circuit is characterized in that, comprises that the output of all controlled resonant converters is connected in parallel with at least two controlled resonant converters of the mode operation of crisscross parallel; The input of each controlled resonant converter is the different power end of separate connection respectively.

2. parallel resonance converter circuit according to claim 1 is characterized in that, said different power end is a plurality of independently DC sources;

The number of said DC source is identical with the number of controlled resonant converter, and the input of each controlled resonant converter connects a DC source.

3. parallel resonance converter circuit according to claim 1 is characterized in that, said different power end is the output of previous stage circuit.

4. according to claim 2 or 3 described parallel resonance converter circuits, it is characterized in that, also comprise an output filter capacitor;

The output of all controlled resonant converters comprises first output and second output, and first output of all controlled resonant converters and second output are connected to the two ends of said output filter capacitor.

5. according to claim 2 or 3 described parallel resonance converter circuits, it is characterized in that said controlled resonant converter is the LLC controlled resonant converter.

6. according to claim 2 or 3 described parallel resonance converter circuits, it is characterized in that when the number of said controlled resonant converter was even number, the misphase angle during each controlled resonant converter crisscross parallel work was the 180/N degree; When the number of said controlled resonant converter was odd number, the misphase angle during each controlled resonant converter crisscross parallel work was (2*180)/N degree; Said N is the number of controlled resonant converter.

7. parallel resonance converter circuit according to claim 1 is characterized in that, when the controlled resonant converter with the crisscross parallel mode operation is two, is respectively first controlled resonant converter and second controlled resonant converter;

The output of the output of first controlled resonant converter and second controlled resonant converter is connected in parallel;

The input of the input of first controlled resonant converter and second controlled resonant converter is the different power end of separate connection respectively.

8. parallel resonance converter circuit according to claim 7 is characterized in that, said power end is first DC source and second DC source;

The input of said first controlled resonant converter connects first DC source; The input of said second controlled resonant converter connects second DC source.

9. according to claim 7 or 8 described parallel resonance converter circuits, it is characterized in that said first controlled resonant converter and the 90 degree operations of the second controlled resonant converter misphase.

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