Voltage equalizing circuit and power conversion system

Abstract

The utility model relates to the technical field of electric power conversion, and discloses a voltage-sharing circuit and a power conversion system, the voltage-sharing circuit comprises a voltage-sharing module, N power conversion modules and N output modules, N is an integer greater than or equal to 2, the alternating current side of each power conversion module is connected with an alternating current power supply, and the output side of each power conversion module is connected with an alternating current power supply. The direct current side of each power conversion module is connected in parallel with the input end of one output module; the output ends of all the output modules are connected in series; and the voltage sharing module is used for controlling power transmission among the power conversion modules based on the direct-current end voltages of the N power conversion modules or partial voltages of the direct-current end voltages, so that the N output modules jointly output an output voltage after the input voltages of the output modules are consistent. The voltage balancing circuit can balance the voltage of a plurality of output ends of the AC power supply and improve the reliability and the working efficiency of the AC power supply.

Description

Technical Field

[0001] The utility model relates to the technical field of power conversion, in particular to a voltage equalizing circuit and a power conversion system. Background Art

[0002] As the core component of DC fast charging piles, the charging power module is a new application field of power electronics technology in the field of new energy electric vehicles. In order to achieve a wide range of charging voltage requirements, the output side of the charging module usually adopts a series-parallel structure. However, when the output is connected in series and the power tubes are running synchronously, due to differences in hardware parameters, the output voltage may be seriously unbalanced, which will greatly affect the product reliability in actual use. Utility Model Content

[0003] Therefore, the technical problem to be solved by the present invention is to solve the problem of unbalanced output voltage caused by the difference in parameters of internal components of the AC power supply in the prior art, thereby providing a voltage equalization circuit and a power conversion system.

[0004] In order to achieve the above object, the utility model provides the following technical solutions:

[0005] In the first aspect, the utility model provides a voltage equalizing circuit, including: a voltage equalizing module, N power conversion modules and N output modules, N is an integer greater than or equal to 2, wherein the AC side of each power conversion module is connected to an AC power supply, and the DC side of each power conversion module is connected in parallel to the input end of an output module; the output ends of all the output modules are connected in series; for different circuit structures of the voltage equalizing module, there are the following two connection methods: when the voltage equalizing module has N first ends and N second ends, wherein the first end of a voltage equalizing module and the second end of a voltage equalizing module constitute a connection unit, and each connection unit is used to be connected to a power conversion module; the first end of each connection unit is connected to any end of the DC side of a power conversion module, and the second end of each connection unit is connected to any end of the AC side of the corresponding power conversion module; the voltage equalizing module is used to connect the power conversion module based on N power conversion modules. The DC terminal voltage of the N power conversion modules is used to control the power transmission between each power conversion module, so that after the input voltage of each output module is consistent, the N output modules jointly output the output voltage; or, when the voltage balancing module has N first ends, N second ends, and N third ends, the first end of a voltage balancing module, the second end of a voltage balancing module, and the third end of a voltage balancing module constitute a connecting unit, and each connecting unit is used to be connected to a power conversion module; the first end and the second end of each connecting unit are correspondingly connected to the two ends of the DC side of a power conversion module, and the third end of each connecting unit is connected to any one end of the AC side of the corresponding power conversion module; the voltage balancing module is used to control the power transmission between each power conversion module based on the voltage division of the DC terminal voltage of the N power conversion modules, so that after the input voltage of each output module is consistent, the N output modules jointly output the output voltage.

[0006] In the voltage equalization circuit provided by the utility model, each power conversion module switches the switch state based on the driving signal of the AC power supply, realizes power transmission between multiple output ends of the AC power supply and the voltage dividing module, and improves the efficiency of the AC power supply.

[0007] Since high voltage transfers power to low voltage between two AC power supply circuits, in order to avoid the problem of serious imbalance in the input voltage of each output module during synchronous driving due to differences in hardware parameters of the power conversion modules, the utility model uses a voltage equalization module to control the power transfer from the high voltage side to the low voltage side, controls power transmission between multiple power conversion modules, reduces the voltage of the output end with a higher voltage level, makes the input voltage of each output module balanced and consistent, and each output module is connected in series to jointly output the output voltage, thereby increasing the output voltage level of the AC power supply and improving the efficiency of the AC power supply.

[0008] In an optional implementation, the power conversion module is a full-bridge circuit composed of transistors.

[0009] In an optional embodiment, when the voltage balancing module has N first ends and N second ends, the voltage balancing module includes: a first transformer and N demagnetization units, the first transformer includes a primary winding and N-1 secondary windings, one demagnetization unit is selected as the primary demagnetization unit, and the remaining demagnetization units are used as secondary demagnetization units, wherein the first end of each demagnetization unit is connected to any end of the AC side of a power conversion module; the same-name end of the primary winding of the first transformer is connected to the second end of the primary demagnetization unit, and the non-same-name end of the primary winding of the first transformer is connected to any end of the DC side of the power conversion module connected to the primary demagnetization unit; the same-name end of the secondary winding of each first transformer is connected to the second end of a secondary demagnetization unit, and the non-same-name end of the secondary winding of each first transformer is connected to any end of the DC side of the power conversion module connected to the corresponding secondary demagnetization unit; each demagnetization unit is used to filter out the DC signal of a same-name end of the first transformer; the first transformer is used to control power transmission between the primary demagnetization unit and the secondary demagnetization unit.

[0010] In an optional embodiment, when the voltage balancing module has N first ends, N second ends, and N third ends, the voltage balancing module includes: a second transformer and N voltage dividing units, the second transformer includes a primary winding and N-1 secondary windings, one voltage dividing unit is selected as the primary voltage dividing unit, and the remaining voltage dividing units are selected as secondary voltage dividing units, wherein the first end and the second end of each voltage dividing unit are respectively connected to the two ends of the DC side of a power conversion module; the same-name end of the primary winding of the second transformer is connected to the third end of the primary voltage dividing unit, and the primary winding of the second transformer is connected to the third end of the primary voltage dividing unit. The non-same-name end is connected to any end of the AC side of the power conversion module connected to the primary voltage-dividing unit; the same-name end of the secondary winding of each second transformer is connected to the third end of a secondary voltage-dividing unit, and the non-same-name end of the secondary winding of each second transformer is connected to any end of the AC side of the power conversion module connected to the corresponding secondary voltage-dividing unit; each voltage-dividing unit is used to divide the voltage at both ends of the DC side of the corresponding power conversion module and input it to a same-name end of the second transformer; the second transformer is used to control power transmission between the primary voltage-dividing unit and the secondary voltage-dividing unit.

[0011] In the voltage equalizing circuit provided by the utility model, the first transformer and the second transformer can actively transmit and transform electric energy according to the voltage levels of the primary side and the secondary side, thereby realizing power transmission between the high-voltage side and the low-voltage side, that is, the voltage equalizing module does not require special logic control, which greatly reduces the cost of the voltage equalizing module.

[0012] In an optional implementation, the demagnetization unit includes: a first capacitor, a first end of which is connected to any end of the AC side of a power conversion module, and a second end of which is connected to a same-name end of the first transformer.

[0013] The voltage balancing circuit provided by the utility model utilizes the first capacitor to filter out the direct current of the primary and secondary sides of the first transformer, so that the first transformer can work normally, thereby improving the working efficiency of the first transformer and reducing the cost of the voltage balancing module.

[0014] In an optional embodiment, the voltage divider unit includes: a second capacitor and a third capacitor, wherein the first end of the second capacitor is connected to the first end of the third capacitor and a like-name end of the second transformer; the second ends of the second capacitor and the third capacitor are respectively connected to the two ends of the DC side of a power conversion module.

[0015] In an optional implementation, the output module includes: a fourth capacitor, a first end and a second end of which are respectively connected to two ends of a DC side of a power conversion module.

[0016] In the second aspect, the utility model provides a power conversion system, comprising: a high-voltage high-power converter and the voltage equalizing circuit of the first aspect, wherein each output end of the high-voltage high-power converter is respectively connected to the AC side of a power conversion module; the output ends of all the output modules are connected in series and then connected in parallel with the load; the voltage equalizing module is used to control the power transmission between each power conversion module so that the input voltage of each output module is consistent, and all the output modules jointly power the load.

[0017] In the power conversion system provided by the utility model, each power conversion module is used to switch the switch state based on the driving signal of the high-voltage high-power converter, so as to realize power transmission between multiple output ends of the AC power supply and the voltage dividing module, thereby improving the efficiency of the high-voltage high-power converter.

[0018] Since high voltage will transfer power to low voltage between two AC power supply circuits, in order to avoid the problem of serious imbalance in the input voltage of the output module during synchronous driving due to differences in hardware parameters of the series-connected power conversion modules, the utility model uses a voltage equalization module to control the power transfer from the high voltage side to the low voltage side, controls the power transmission between the output ends of multiple power conversion modules, reduces the voltage of the output end with a higher voltage level, makes the input voltage of each output module balanced and consistent, and each output module is connected in series to output the output voltage together, thereby improving the output voltage level of the high-voltage and high-power converter and improving the reliability of the power conversion system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A composition diagram of a specific example of a voltage balancing circuit when the voltage balancing module has N first terminals and N second terminals according to an embodiment of the utility model;

[0021] Figure 2 A composition diagram of a specific example of a voltage balancing circuit when the voltage balancing module has N first terminals, N second terminals, and N third terminals according to an embodiment of the utility model;

[0022] Figure 3 A composition diagram of a specific example of a pressure equalizing module according to an embodiment of the present utility model;

[0023] Figure 4 A structural diagram of a specific circuit of a voltage equalizing circuit when N=2 according to an embodiment of the utility model;

[0024] Figure 5 This is a structural diagram of another specific circuit of the voltage balancing module when N=2 according to an embodiment of the utility model;

[0025] Figure 6 This is a structural diagram of a specific circuit of a voltage balancing module when N=3 according to an embodiment of the utility model;

[0026] Figure 7 It is a composition diagram of another specific example of the pressure equalizing module of the embodiment of the utility model;

[0027] Figure 8 This is a structural diagram of another specific circuit of the voltage balancing module when N=2 according to an embodiment of the utility model;

[0028] Fig. 9 This is a structural diagram of another specific circuit of the voltage balancing module when N=2 according to an embodiment of the utility model;

[0029] Fig.10 This is a structural diagram of another specific circuit of the voltage balancing module when N=3 according to an embodiment of the utility model;

[0030] Fig.11 A composition diagram of a specific example of a power conversion system when the voltage balancing module has N first terminals and N second terminals according to an embodiment of the utility model;

[0031] Fig.12This is a composition diagram of a specific example of a power conversion system when the voltage balancing module has N first ends and N second ends according to an embodiment of the utility model. DETAILED DESCRIPTION

[0032] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0035] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] In the related art, in order to achieve the wide range of output voltage requirements of the AC power supply, a series-parallel structure is usually adopted on the output side of the AC power supply. However, when the output is connected in series and the power tubes are running synchronously, due to the difference in hardware parameters on the output side, the output voltage may be seriously unbalanced, resulting in reduced reliability of the AC power supply. To avoid the above problems,

[0037] This embodiment provides a voltage equalization circuit, such as Figure 1 , Figure 2As shown, it includes: a voltage equalizing module 2, N power conversion modules (i.e., the 1st power conversion module #11 to the Nth power conversion module #1N) and N output modules (i.e., the 1st output module #31 to the Nth output module #3N), N is an integer greater than or equal to 2, wherein the AC side of each power conversion module is connected to an AC power supply, and the DC side of each power conversion module is connected in parallel to the input end of an output module; and the output ends of all the output modules are connected in series.

[0038] Specifically, Figure 1 , Figure 2 In the embodiment, when each power conversion module is connected in series inside the AC power supply, a voltage equalization module 2 is added between the output end of each power conversion module and the input end of the corresponding output module to solve the problem of unbalanced output voltage caused by differences in component parameters inside the AC power supply in the prior art.

[0039] like Figure 1 and Figure 2 As shown, for different circuit structures of the voltage balancing module 2, there are the following two connection methods:

[0040] (1) Figure 1 As shown, when the voltage equalizing module 2 has N first ends and N second ends, the first end of a voltage equalizing module 2 and the second end of a voltage equalizing module 2 constitute a connecting unit, and each connecting unit is used to connect to a power conversion module; the first end of each connecting unit is connected to any end of the DC side of a power conversion module, and the second end of each connecting unit is connected to any end of the AC side of the corresponding power conversion module.

[0041] For example, Figure 1 In the example, the first end of each connection unit is connected to the negative DC end of a power conversion module, and the second end of each connection unit is connected to the first AC side of the corresponding power conversion module. Each power conversion module is used to output a corresponding voltage signal after switching the switch state based on the driving signal of the AC power supply, so as to increase each output end of the AC power supply to the same voltage level. However, due to the different degrees of loss of components in different power conversion modules, or due to the influence of different manufacturing processes, the parameters inside different power conversion modules are inconsistent, and the input voltage of each output module is seriously unbalanced. Therefore, it is necessary to introduce a voltage equalization module 2 to balance the voltage.

[0042] Specifically, Figure 1In the figure, the voltage equalization module 2 is used to control the power transmission between the output ends of each power conversion module based on the DC terminal voltage of N power conversion modules. It uses the principle of transferring power from the high-voltage side to the low-voltage side to reduce the output voltage of the power conversion module with a higher voltage level and increase the output voltage of the power conversion module with a lower voltage level, so that the input voltage of each output module is consistent, and it can reliably provide a high-voltage and high-power output voltage U0 for the subsequent circuit, thereby achieving the purpose of voltage balance and improving the power supply capacity and reliability of the AC power supply.

[0043] It should be noted that the second end of each connection unit should be connected to the first AC end of the corresponding power conversion module, or connected to the second AC end of the corresponding power conversion module, and the control principle of the voltage equalization circuit is the same under the two connection modes. In addition, the specific positions of the positive and negative DC ends of the power conversion module are not limited. The first end of each connection unit should be connected to the positive DC end of the corresponding power conversion module, or connected to the negative DC end of the corresponding power conversion module, so that the output voltage U0 switches different power supply directions.

[0044] (2) Figure 2 As shown, when the voltage equalizing module 2 has N first ends, N second ends, and N third ends, the first end of a voltage equalizing module 2, the second end of a voltage equalizing module 2, and the third end of a voltage equalizing module 2 constitute a connecting unit, and each connecting unit is used to connect to a power conversion module; the first end and the second end of each connecting unit are correspondingly connected to the two ends of the DC side of a power conversion module, and the third end of each connecting unit is connected to any end of the AC side of the corresponding power conversion module.

[0045] For example, Figure 2 Taking the example in which the third end of each connection unit is connected to the first AC side of the corresponding power conversion module, the voltage equalizing module 2 is used to control the power transmission between each power conversion module based on the voltage division of the DC end voltage of N power conversion modules, so that after the input voltage of each output module is consistent, the N output modules jointly output the output voltage U0.

[0046] It should be noted that the third end of each connection unit should be commonly connected to the first AC end of the corresponding power conversion module, or commonly connected to the second AC end of the corresponding power conversion module. The control principle of the voltage equalization circuit is the same in both connection modes.

[0047] In the voltage equalization circuit provided in this embodiment, each power conversion module switches the switch state based on the driving signal of the AC power supply, thereby realizing power transmission between multiple output ends of the AC power supply and the voltage dividing module, thereby improving the efficiency of the AC power supply.

[0048] Since high voltage transfers power to low voltage between two AC power supply circuits, in order to avoid the problem of serious imbalance in the input voltage of each output module during synchronous driving due to differences in hardware parameters of the power conversion modules, the utility model uses a voltage equalization module to control the power transfer from the high voltage side to the low voltage side, controls power transmission between multiple power conversion modules, reduces the voltage of the output end with a higher voltage level, makes the input voltage of each output module balanced and consistent, and each output module is connected in series to jointly output the output voltage, thereby increasing the output voltage level of the AC power supply and improving the efficiency of the AC power supply.

[0049] In some optional embodiments, such as Figure 3 As shown, when the voltage balancing module has N first terminals and N second terminals, the voltage balancing module 2 includes: a first transformer T1 and N demagnetization units (ie Figure 3 The first transformer T1 includes a primary winding and N-1 secondary windings. One demagnetization unit is selected as the primary demagnetization unit #211, the second secondary demagnetization unit #212 to the Nth secondary demagnetization unit #21N. The first transformer T1 includes a primary winding and N-1 secondary windings. One demagnetization unit is selected as the primary demagnetization unit #211, and the remaining demagnetization units are selected as secondary demagnetization units (i.e. Figure 3 The second secondary demagnetization unit #212 to the Nth secondary demagnetization unit #21N), wherein the first end of each demagnetization unit is connected to any end of the AC side of a power conversion module.

[0050] like Figure 3 As shown, the same-name end of the primary winding of the first transformer T1 is connected to the second end of the primary demagnetization unit #211, and the non-same-name end of the primary winding of the first transformer T1 is connected to any end of the DC side of the power conversion module (i.e., the first power conversion module #11) connected to the primary demagnetization unit #211; the same-name end of the secondary winding of each first transformer T1 is connected to the second end of a secondary demagnetization unit, and the non-same-name end of each secondary winding of the first transformer T1 is connected to any end of the DC side of the power conversion module connected to the corresponding secondary demagnetization unit.

[0051] It should be noted that in the present embodiment, the first end of each demagnetization unit should be commonly connected to the first AC end of the corresponding power conversion module, or commonly connected to the second AC end of the corresponding power conversion module; the two ends of the DC side of each power conversion module are assumed to be positive at the top and negative at the bottom, and the specific positions of the positive and negative DC ends of the power conversion module are not restricted. Each non-same-name end of the first transformer T1 should be commonly connected to the positive DC end of the corresponding power conversion module, or commonly connected to the negative DC end of the corresponding power conversion module, so that the output voltage U0 switches different power supply directions.

[0052] For example, Figure 3In the example, the first end of each demagnetization unit is connected to the first AC side of a power conversion module, and each non-same-name end of the first transformer T1 is respectively connected to the negative DC end of a power conversion module. Each demagnetization unit is used to filter out the DC signal of a same-name end of the first transformer T1; the first transformer T1 is used to control power transmission between the primary demagnetization unit #211 and each secondary demagnetization unit.

[0053] Specifically, Figure 3 In the embodiment, when the 1st power conversion module #11 to the Nth power conversion module #1N switch the switch state under the synchronous driving signal of the AC power supply, the primary winding and the secondary winding of the first transformer T1 both generate high-frequency square waves. If the hardware parameters of the 1st power conversion module #11 to the Nth power conversion module #1N are consistent, all the high-frequency square waves should have the same frequency and amplitude.

[0054] Specifically, Figure 3 In the example, when there are hardware differences between the 1st power conversion module #11 to the Nth power conversion module #1N, the power output by the 1st power conversion module #11 to the Nth power conversion module #1N is inconsistent. When the voltage output by any power conversion module is unbalanced, the amplitude of the corresponding high-frequency square wave will be inconsistent. According to the equivalent model of the transformer, in the AC system, the high voltage will transfer power to the low voltage, and the first transformer T1 plays the role of transferring energy. The demagnetization unit is used to filter out the DC signal in the high-frequency square wave and convert the high-frequency square wave into an AC signal so that it can be transmitted through the first transformer T1. The first transformer T1 transfers power from the high-voltage side to the low-voltage side, thereby reducing the voltage on the high-voltage side and increasing the voltage on the low-voltage side, and finally achieving the purpose of balancing the voltage at the input end of each output module.

[0055] For example, Figure 4 In the example, the AC power source includes two groups of output ports, that is, N=2, the first power conversion module #11 includes the first switch tube Q1 to the fourth switch tube Q4, the second power conversion module #12 includes the fifth switch tube Q5 to the eighth switch tube Q8, and Q1 to Q8 switch the switch state based on the synchronous drive signal of the AC power source. Q1 to Q8 can also be replaced by diodes with the same function, and the specific component type is not limited here.

[0056] Specifically, Figure 4In the embodiment, the primary demagnetization unit #211 includes a first capacitor (i.e., C11), and the second secondary demagnetization unit #212 includes a first capacitor (i.e., C12). The first end of C11 and the first end of C12 are respectively connected to the same-name end of the primary winding and the same-name end of the secondary winding of the first transformer T1, the second end of C11 is connected to the first end of Q3, the first end of Q4 and the first AC end of the first power conversion module #11, and the second end of C12 is connected to the first end of Q7, the first end of Q8 and the first AC end of the second power conversion module #12. The non-same-name ends of the primary winding and the secondary winding of the first transformer T1 are respectively connected to the negative DC end of the first power conversion module #11 and the negative DC end of the second power conversion module #12. The first output module #31 includes a fourth capacitor (i.e., C31) and the second output module #32 includes a fourth capacitor (i.e., C32). C31 is connected in parallel to the DC side of the first power conversion module #11, and C32 is connected in parallel to the DC side of the second power conversion module #12. The U0 side can be connected to the load to supply power to the load.

[0057] Specifically, Figure 4 In the figure, Q1 and Q5, Q2 and Q6, Q3 and Q7, Q4 and Q8 are driven synchronously. When the hardware parameters of the first power conversion module #11 and the second power conversion module #12 are consistent, and when Q2 and Q3 are turned on, and Q1 and Q4 are turned off, a voltage of U0 / 2 is generated between the midpoint of Q3 and Q4 and the non-same-name end of the primary winding of the first transformer T1. When Q2 and Q3 are turned off, and Q1 and Q4 are turned on, a voltage of 0V is generated between the midpoint of Q3 and Q4 and the non-same-name end of the primary winding of the first transformer T1. Therefore, a high-frequency square wave S1 (0, 1) is generated between the midpoint of Q3 and Q4 and the non-same-name end of the primary winding of the first transformer T1. Similarly, a high-frequency square wave S2 (0, 1) is generated between the midpoint of Q7 and Q8 and the non-same-name end of the secondary winding of the first transformer T1. S1 and S2 have the same frequency, amplitude and phase.

[0058] Specifically, Figure 4 In the example, due to hardware differences, the power output from the DC side of the first power conversion module #11 and the second power conversion module #12 will be inconsistent, which will lead to inconsistent voltages at both ends of C31 and C32, and serious unbalanced output voltages. When the power output from the DC side of the first power conversion module #11 and the second power conversion module #12 is inconsistent, the voltages borne by C31 and C32 will also be different, resulting in inconsistent amplitudes of square waves S1 and S2.

[0059] Specifically, Figure 4According to the equivalent model of the transformer, in the two AC power systems, the high-voltage side will transfer power to the low-voltage side, that is, the first transformer T1 plays the role of transferring energy. Since S1 and S2 are both high-frequency square waves, it is necessary to demagnetize the first capacitor to filter out the DC signal in the high-frequency square wave, so that the high-frequency square wave is converted into an AC signal so that it can be transmitted through the first transformer T1. The first transformer T1 transfers power from the high-voltage side to the low-voltage side, thereby reducing the voltage on the high-voltage side and increasing the voltage on the low-voltage side, and finally achieving the purpose of making the voltages borne by C31 and C32 the same and balancing the voltage on the load side.

[0060] It should be noted that, since each group of output ports of the AC power supply has two ports, the first output port and the second output port, and the AC side of each power conversion module includes the first AC port and the second AC port, the second end of the first capacitor can be as follows: Figure 4 As shown, they are connected to the first AC terminals of the corresponding power conversion modules respectively, and can also be connected according to Figure 5 As shown, they are respectively connected to the second AC ends of the corresponding power conversion modules.

[0061] Specifically, Figure 5 In the figure, the first end of C11 and the first end of C12 are connected to the same-name end of the primary winding and the same-name end of the secondary winding of the first transformer T1, respectively; the second end of C11 is connected to the first end of Q1, the first end of Q2 and the second AC end of the first power conversion module #11; the second end of C12 is connected to the first end of Q5, the first end of Q6 and the second AC end of the second power conversion module #12. The non-same-name ends of the primary winding and the secondary winding of the first transformer T1 are connected to the negative DC end of the first power conversion module #11 and the negative DC end of the second power conversion module #12, respectively; C31 is connected in parallel to the DC side of the first power conversion module #11; C32 is connected in parallel to the DC side of the second power conversion module #12; and the U0 side can be connected to the load to supply power to the load. Figure 5 and Figure 4 The control principle is the same as that of the conventional ones, only the connection relationship is different, and the control principle will not be repeated here.

[0062] For example, Figure 6 This is a specific circuit diagram of the voltage equalization circuit when the AC power supply includes three groups of output ports, that is, N=3. The first power conversion module #11 includes the first switch tube Q1 to the fourth switch tube Q4, the second power conversion module #12 includes the fifth switch tube Q5 to the eighth switch tube Q8, and the third power conversion module #13 includes the ninth switch tube Q9 to the twelfth switch tube Q12. Q1~Q12 switch states based on the synchronous drive signal of the AC power supply.

[0063] It should be noted that the power conversion module can also be a three-phase bridge circuit, and its specific internal structure is not limited here.

[0064] Specifically, Figure 6 In the embodiment, the first end of C11 is connected to the same-name end of the primary winding of the first transformer T1, the first end of C12 and the first end of C13 are respectively connected to the same-name end of the secondary winding of the first transformer T1, the second end of C11 is connected to the first end of Q3, the first end of Q4 and the first AC end of the first power conversion module #11, the second end of C12 is connected to the first end of Q7, the first end of Q8 and the first AC end of the second power conversion module #12, and the second end of C13 is connected to the first end of Q11, the first end of Q12 and the first AC end of the third power conversion module #13.

[0065] Specifically, Figure 6 In the figure, the non-same-named ends of the primary winding of the first transformer T1 are connected to the negative DC end of the first power conversion module #11, the two non-same-named ends of the secondary winding of the first transformer T1 are respectively connected to the negative DC end of the second power conversion module #12 and the negative DC end of the third power conversion module #13, C31~C33 are respectively connected in parallel with the DC sides of the first power conversion module #11~the third power conversion module #13, and the U0 side can be connected to the load to supply power to the load.

[0066] It should be noted that the control principles of the first power conversion module #11 to the third power conversion module #13, the primary side demagnetization unit #211 to the third secondary side demagnetization unit #213, and the first output module #31 to the third output module #33 are consistent with the above contents. Figure 4 The number of power conversion modules shown is different, and when N=4, 5 or any integer, it can refer to Figure 6 The circuit principles are consistent with the above contents and will not be described in detail here.

[0067] In some optional embodiments, such as Figure 7 As shown, when the voltage balancing module 2 has N first ends, N second ends, and N third ends, the voltage balancing module 2 includes: a second transformer T2 and N voltage dividing units (i.e., a primary voltage dividing unit #221, a second secondary voltage dividing unit #222 to an Nth secondary voltage dividing unit #22N), the second transformer T2 includes a primary winding and N-1 secondary windings, one voltage dividing unit is selected as the primary voltage dividing unit #221, and the remaining voltage dividing units are selected as secondary voltage dividing units (i.e., the second secondary voltage dividing unit #222 to the Nth secondary voltage dividing unit #22N), wherein the first end and the second end of each voltage dividing unit are respectively connected to the two ends of the DC side of a power conversion module.

[0068] like Figure 7As shown, the same-name end of the primary winding of the second transformer T2 is connected to the third end of the primary voltage-dividing unit #221, and the non-same-name end of the primary winding of the second transformer T2 is connected to any end of the AC side of the power conversion module (i.e., the first power conversion module #11) connected to the primary voltage-dividing unit #221; the same-name end of the secondary winding of each second transformer T2 is connected to the third end of a secondary voltage-dividing unit, and the non-same-name end of the secondary winding of each second transformer T2 is connected to any end of the AC side of the power conversion module connected to the corresponding secondary voltage-dividing unit.

[0069] It should be noted that in this embodiment, each non-same-name end of the second transformer T2 should be connected to the first AC end of the corresponding power conversion module, or connected to the second AC end of the corresponding power conversion module, so as to achieve synchronous conversion of each power conversion module under the control of the AC power supply, and ensure that each output module receives the input voltage synchronously. Both ends of the DC side of each power conversion module are assumed to be positive at the top and negative at the bottom, and the specific positions of the positive and negative DC ends of the power conversion module are not limited.

[0070] For example, Figure 7 In the example, each non-same-name end of the second transformer T2 is connected to the first AC side of a power conversion module, each voltage divider unit is used to divide the voltage at both ends of the DC side of the corresponding power conversion module and input it to a same-name end of the second transformer T2; the second transformer T2 is used to control power transmission between the primary side voltage divider unit #221 and the secondary side voltage divider unit.

[0071] Specifically, Figure 7 In the embodiment, when the 1st power conversion module #11 to the Nth power conversion module #1N switch the switch state under the synchronous driving signal of the AC power supply, the voltage divider unit divides the output voltage U0, and the non-same-name ends of the primary winding and the secondary winding of the second transformer T2 all generate high-frequency square waves. If the hardware parameters of the 1st power conversion module #11 to the Nth power conversion module #1N are consistent, all the high-frequency square waves should have the same frequency and amplitude.

[0072] Specifically, Figure 7In the example, when there are hardware differences between the 1st power conversion module #11 to the Nth power conversion module #1N, the power output by the 1st power conversion module #11 to the Nth power conversion module #1N is inconsistent. When the voltage output by any power conversion module is unbalanced, the amplitude of the corresponding high-frequency square wave will be inconsistent. According to the equivalent model of the transformer, in the AC power system, the high voltage will transfer power to the low voltage, and the second transformer T2 plays the role of transferring energy. The voltage divider unit is used to divide the output voltage U0 so that the primary winding and the secondary winding of the second transformer T2 generate the corresponding high-frequency square wave, and the high-frequency square wave is transmitted through the second transformer T2. The second transformer T2 performs power transfer from the high-voltage side to the low-voltage side, thereby reducing the voltage on the high-voltage side and increasing the voltage on the low-voltage side, and finally achieving the purpose of balancing the voltage at the input end of each output module.

[0073] For example, Figure 8 In the example, the AC power source includes two groups of output ports, that is, N=2, the first power conversion module #11 includes the first switch tube Q1 to the fourth switch tube Q4, the second power conversion module #12 includes the fifth switch tube Q5 to the eighth switch tube Q8, and Q1 to Q8 switch the switch state based on the synchronous drive signal of the AC power source. Q1 to Q8 can also be replaced by diodes with the same function, and the specific component type is not limited here.

[0074] Specifically, Figure 8 In the embodiment, the primary voltage divider unit #221 includes a second capacitor (i.e., C21) and a third capacitor (i.e., C22), and the second secondary voltage divider unit #222 includes a second capacitor (i.e., C23) and a third capacitor (i.e., C24), wherein a first end of C21 is connected to a first end of C22 and the same-name end of the primary winding of the second transformer, a second end of C21 is connected to a positive DC end of the first power conversion module #11, a second end of C22 is connected to a negative DC end of the first power conversion module #11, a first end of C23 is connected to a first end of C24 and the same-name end of the secondary winding of the second transformer, a second end of C23 is connected to a positive DC end of the second power conversion module #12, and a second end of C24 is connected to a negative DC end of the second power conversion module #12.

[0075] Specifically, Figure 8 In the embodiment, the non-same-name ends of the primary winding and the secondary winding of the second transformer T2 are respectively connected to the first AC end of the first power conversion module #11 and the first AC end of the second power conversion module #12, the first output module #31 includes a fourth capacitor (i.e., C31), and the second output module #32 includes a fourth capacitor (i.e., C32), C31 is connected in parallel with the DC side of the first power conversion module #11, and C32 is connected in parallel with the DC side of the second power conversion module #12, and the U0 side can be connected to the load to supply power to the load.

[0076] Specifically, Figure 8 In the example, Q1 and Q5, Q2 and Q6, Q3 and Q7, Q4 and Q8 are driven synchronously. When the hardware parameters of the first power conversion module #11 and the second power conversion module #12 are consistent, and when Q2 and Q3 are turned on, and Q1 and Q4 are turned off, the primary winding voltage of the second transformer T2 is U0 / 4; when Q2 and Q3 are turned off, and Q1 and Q4 are turned on, the primary winding voltage of the second transformer T2 is -U0 / 4. Therefore, the same-name end of the primary winding of the second transformer T2 and the non-same-name end of the primary winding of the second transformer T2 generate a high-frequency square wave S3 (-1, 1). Similarly, the same-name end of the secondary winding of the second transformer T2 and the non-same-name end of the secondary winding of the second transformer T2 generate a high-frequency square wave S4 (-1, 1), and S3 and S4 have the same frequency, same amplitude and same phase.

[0077] Specifically, Figure 8 In the example, due to hardware differences, the power outputted by the DC side of the first power conversion module #11 and the second power conversion module #12 will be inconsistent, which will lead to inconsistent voltages at both ends of C31 and C32, and serious unbalanced output voltage. When the power outputted by the DC side of the first power conversion module #11 and the second power conversion module #12 is inconsistent, the voltages borne by C31 and C32 will also be different, making the midpoint voltage of the voltage at both ends of C31 after voltage division by C21 and C22, and the midpoint voltage of the voltage at both ends of C32 after voltage division by C23 and C24 unequal, which will lead to inconsistent amplitudes of high-frequency square wave S3 and high-frequency square wave S4.

[0078] Specifically, Figure 8 In the figure, according to the equivalent model of the transformer, in the two AC power systems, the high voltage side will transfer power to the low voltage side, that is, the second transformer T2 plays the role of transferring energy. When the amplitudes of the high-frequency square wave S3 and the high-frequency square wave S4 are different, the high-frequency square wave S3 and the high-frequency square wave S4 transfer power through the second transformer T2. The second transformer T2 transfers power from the high voltage side to the low voltage side, thereby reducing the voltage on the high voltage side and increasing the voltage on the low voltage side, and finally achieving the purpose of making the voltages on C31 and C32 the same and balancing the voltage on the load side.

[0079] It should be noted that, since each output end of the AC power supply has two ports, the first output end and the second output end, and the AC side of each power conversion module includes the first AC end and the second AC end, the non-same-name ends of the second transformer T2 can be as follows: Figure 8 As shown, they are connected to the first AC terminals of the corresponding power conversion modules respectively, and can also be connected according to Fig. 9 As shown, they are respectively connected to the second AC ends of the corresponding power conversion modules.

[0080] Specifically, Fig. 9In the embodiment, the first end of C21 is connected to the first end of C22 and the same-name end of the primary winding of the second transformer T2, the second end of C21 is connected to the positive DC end of the first power conversion module #11, the second end of C22 is connected to the negative DC end of the first power conversion module #11, the first end of C23 is connected to the first end of C24 and the same-name end of the secondary winding of the second transformer, the second end of C23 is connected to the positive DC end of the second power conversion module #12, and the second end of C24 is connected to the negative DC end of the second power conversion module #12.

[0081] Specifically, Fig. 9 In the embodiment, the non-same-named ends of the primary winding and the secondary winding of the second transformer T2 are connected to the second AC end of the first power conversion module #11 and the second AC end of the second power conversion module #12 respectively. Fig. 9 and Figure 8 The control principle is the same as that of the conventional ones, only the connection relationship is different, and the control principle will not be repeated here.

[0082] Specifically, Fig.10 This is a specific circuit diagram of the voltage equalization circuit when the AC power supply includes three groups of output ports, that is, N=3. The first power conversion module #11 includes the first switch tube Q1 to the fourth switch tube Q4, the second power conversion module #12 includes the fifth switch tube Q5 to the eighth switch tube Q8, and the third power conversion module #13 includes the ninth switch tube Q9 to the twelfth switch tube Q12. Q1~Q12 switch states based on the synchronous drive signal of the AC power supply.

[0083] Specifically, Fig.10 In the embodiment, the first end of C21 is connected to the first end of C22 and the same-name end of the primary winding of the second transformer, the second end of C21 is connected to the positive DC end of the first power conversion module #11, and the second end of C22 is connected to the negative DC end of the first power conversion module #11; the first end of C23 is connected to the first end of C24 and the same-name end of a secondary winding of the second transformer, the second end of C23 is connected to the positive DC end of the second power conversion module #12, and the second end of C24 is connected to the negative DC end of the second power conversion module #12; the first end of C25 is connected to the first end of C26 and the same-name end of another secondary winding of the second transformer, the second end of C25 is connected to the positive DC end of the third power conversion module #13, and the second end of C26 is connected to the negative DC end of the third power conversion module #13.

[0084] Specifically, Fig.10In the embodiment, the non-same-named ends of the primary winding of the second transformer T2 are connected to the first AC end of the first power conversion module #11, the two non-same-named ends of the secondary winding of the first transformer T1 are respectively connected to the first AC end of the second power conversion module #12 and the first AC end of the third power conversion module #13, C31~C33 are respectively connected in parallel with the DC sides of the first power conversion module #11~the third power conversion module #13, and the U0 side can be connected to the load to supply power to the load.

[0085] It should be noted that the control principles of the first power conversion module #11 to the third power conversion module #13, the primary voltage divider unit #221 to the third secondary voltage divider unit #223, and the first output module #31 to the third output module #33 are consistent with the above content, and only differ from Figure 8 The number of power conversion modules shown is different, and when N=4, 5 or any integer, it can refer to Fig.10 The circuit principles are consistent with the above contents and will not be described in detail here.

[0086] This embodiment provides a power conversion system, such as Fig.11 As shown, it includes: a high-voltage high-power converter 4 and the above embodiments and any optional implementation methods thereof Figure 1 The voltage equalization circuit in Fig.12 As shown, including high voltage high power converter 4 and the above embodiments and any optional implementation method thereof Figure 2 The voltage equalizing circuit in the embodiment of the present invention comprises: each output end of the high-voltage high-power converter 4 is respectively connected to the AC side of a power conversion module; the output ends of all the output modules (i.e., the first output module #31 to the Nth output module #3N) are connected in series and then connected in parallel with the load R0; the voltage equalizing module 2 is used to control the power transmission between each power conversion module (i.e., the first power conversion module #11 to the Nth power conversion module #1N) so that the input voltage of each output module is consistent, and then all the output modules jointly supply power to the load R0.

[0087] Specifically, when the voltage balancing module 2 has N first terminals and N second terminals, Fig.11 As shown, the first end of a voltage equalizing module 2 and the second end of a voltage equalizing module 2 constitute a connecting unit, and each connecting unit is used to connect to a power conversion module; the first end of each connecting unit is connected to any end of the DC side of a power conversion module, and the second end of each connecting unit is connected to any end of the AC side of the corresponding power conversion module.

[0088] Specifically, when the voltage balancing module 2 has N first terminals, N second terminals, and N third terminals, as Fig.12As shown, the first end of a voltage equalizing module 2, the second end of a voltage equalizing module 2 and the third end of a voltage equalizing module 2 constitute a connecting unit, and each connecting unit is used to connect to a power conversion module; the first end and the second end of each connecting unit are correspondingly connected to the two ends of the DC side of a power conversion module, and the third end of each connecting unit is connected to any end of the AC side of the corresponding power conversion module.

[0089] Specifically, refer to Fig.11 and Fig.12 The voltage equalizing module 2 is used to control the power transmission between the output ends of each power conversion module. It uses the principle of transferring power from the high-voltage side to the low-voltage side to reduce the voltage at the output end of the power conversion module with a higher voltage level and increase the voltage at the output end of the power conversion module with a lower voltage level, so that the voltage at the input end of each output module is consistent, and can reliably provide high-voltage and high-power power supply to the load R0, achieving the purpose of voltage balance while improving the power supply capacity and reliability of the high-voltage and high-power converter 4.

[0090] In the power conversion system provided in this embodiment, each power conversion module is used to switch the switch state based on the driving signal of the high-voltage high-power converter, so as to realize power transmission between multiple output ends of the AC power supply and the voltage divider module, thereby improving the efficiency of the high-voltage high-power converter.

[0091] Since high voltage will transfer power to low voltage between two AC power supply circuits, in order to avoid the problem of serious imbalance in the input voltage of the output module during synchronous driving due to differences in hardware parameters of the series-connected power conversion modules, the utility model uses a voltage equalization module to control the power transfer from the high voltage side to the low voltage side, controls the power transmission between the output ends of multiple power conversion modules, reduces the voltage of the output end with a higher voltage level, makes the input voltage of each output module balanced and consistent, and each output module is connected in series to output the output voltage together, thereby improving the output voltage level of the high-voltage and high-power converter and improving the reliability of the power conversion system.

[0092] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A voltage equalizing circuit, characterized in that: include: A voltage balancing module, N power conversion modules and N output modules, N is an integer greater than or equal to 2, wherein: The AC side of each of the power conversion modules is connected to an AC power source, and the DC side of each of the power conversion modules is connected in parallel to an input end of one of the output modules; The output ends of all the output modules are connected in series; For different circuit structures of the voltage balancing module, there are two connection methods: When the voltage balancing module has N first ends and N second ends, the first end of one voltage balancing module and the second end of one voltage balancing module constitute a connection unit, and each connection unit is used to connect to one power conversion module; the first end of each connection unit is connected to any end of the DC side of one power conversion module, and the second end of each connection unit is connected to any end of the AC side of the corresponding power conversion module; the voltage balancing module is used to control the power transmission between each power conversion module based on the DC end voltage of the N power conversion modules, so that after the input voltage of each output module is consistent, the N output modules jointly output the output voltage; Alternatively, when the voltage balancing module has N first ends, N second ends, and N third ends, the first end of one of the voltage balancing modules, the second end of one of the voltage balancing modules, and the third end of one of the voltage balancing modules constitute a connecting unit, and each connecting unit is used to be connected to one of the power conversion modules; the first end and the second end of each connecting unit are correspondingly connected to the two ends of the DC side of one of the power conversion modules, and the third end of each connecting unit is connected to any one end of the AC side of the corresponding power conversion module; the voltage balancing module is used to control power transmission between each of the power conversion modules based on the voltage division of the DC end voltages of the N power conversion modules, so that after the input voltage of each of the output modules is consistent, the N output modules jointly output the output voltage.

2. The voltage balancing circuit according to claim 1, characterized in that: The power conversion module is a full-bridge circuit composed of transistors.

3. The voltage balancing circuit according to claim 1, characterized in that: When the voltage balancing module has N first ends and N second ends, the voltage balancing module includes: a first transformer and N demagnetization units, the first transformer includes a primary winding and N-1 secondary windings, one demagnetization unit is selected as the primary demagnetization unit, and the remaining demagnetization units are selected as secondary demagnetization units, wherein: The first end of each of the demagnetization units is connected to any one end of the AC side of one of the power conversion modules; The same-name end of the primary winding of the first transformer is connected to the second end of the primary demagnetization unit, and the non-same-name end of the primary winding of the first transformer is connected to any end of the DC side of the power conversion module connected to the primary demagnetization unit; The same-name end of each secondary winding of the first transformer is connected to the second end of one of the secondary demagnetization units, and the non-same-name end of each secondary winding of the first transformer is connected to any end of the DC side of the power conversion module connected to the corresponding secondary demagnetization unit; Each of the demagnetization units is used to filter out a DC signal of a same-name end of the first transformer; The first transformer is used to control power transmission between the primary demagnetization unit and the secondary demagnetization unit.

4. The voltage balancing circuit according to claim 1, characterized in that: When the voltage balancing module has N first terminals, N second terminals, and N third terminals, the voltage balancing module includes: a second transformer and N voltage dividing units, the second transformer includes a primary winding and N-1 secondary windings, one voltage dividing unit is selected as the primary voltage dividing unit, and the remaining voltage dividing units are selected as the secondary voltage dividing units, wherein, The first end and the second end of each voltage dividing unit are respectively connected to the two ends of the DC side of one of the power conversion modules; The same-name end of the primary winding of the second transformer is connected to the third end of the primary voltage divider unit, and the non-same-name end of the primary winding of the second transformer is connected to any end of the AC side of the power conversion module connected to the primary voltage divider unit; The same-name end of each secondary winding of the second transformer is connected to the third end of one of the secondary voltage divider units, and the non-same-name end of each secondary winding of the second transformer is connected to any end of the AC side of the power conversion module connected to the corresponding secondary voltage divider unit; Each of the voltage dividing units is used to divide the voltage at both ends of the DC side of the corresponding power conversion module and input it to a same-named end of the second transformer; The second transformer is used to control power transmission between the primary voltage dividing unit and the secondary voltage dividing unit.

5. The voltage balancing circuit according to claim 3, characterized in that: The demagnetization unit comprises: A first capacitor has a first end connected to any one end of the AC side of one of the power conversion modules, and a second end connected to a same-named end of the first transformer.

6. The voltage balancing circuit according to claim 4, characterized in that: The voltage dividing unit includes: a second capacitor and a third capacitor, wherein: a second capacitor, a first end of which is connected to the first end of the third capacitor and a like-named end of the second transformer; The second ends of the second capacitor and the third capacitor are respectively connected to the two ends of the DC side of one of the power conversion modules.

7. The voltage balancing circuit according to any one of claims 1 to 6, characterized in that: The output module comprises: A fourth capacitor has a first end and a second end connected to two ends of a DC side of one of the power conversion modules.

8. A power conversion system, characterized in that: include: A high-voltage and high-power converter and a voltage balancing circuit as claimed in any one of claims 1 to 6, wherein: Each output end of the high-voltage high-power converter is respectively connected to the AC side of a power conversion module; The output terminals of all output modules are connected in series and then connected in parallel with the load; The voltage balancing module is used to control the power transmission between each of the power conversion modules so that the input voltage of each of the output modules is consistent, and then all of the output modules jointly supply power to the load.

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