Control method of power conversion circuit, power conversion device and energy storage equipment

Abstract

The invention provides a control method of a power conversion circuit, a power conversion device and energy storage equipment. The power conversion device comprises N power conversion circuits which are connected in parallel, and the control method comprises the steps of obtaining actual output parameters of the N power conversion circuits, obtaining a reference parameter according to the N actual output parameters, then obtaining initial adjustment parameters of the N power conversion circuits according to a difference value between the N actual output parameters and the reference parameter, n initial adjustment parameters, N actual output parameters and set reference parameters are obtained, target adjustment parameters of the N power conversion circuits are obtained according to the N initial adjustment parameters, the N actual output parameters and set reference parameters, control signals are generated according to the N target adjustment parameters, and the control signals are used for controlling the target output parameters of the N power conversion circuits so that the output power of the N power conversion circuits can be balanced. Therefore, the conditions of overstress failure of components and circuit damage caused by power imbalance are avoided.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a control method for a power conversion circuit, a power conversion device, and an energy storage device. Background Art

[0002] In high-power scenarios, power conversion circuits usually need to be operated in parallel to share high currents, or in series to share high voltages. Due to manufacturing errors and tolerance design of circuit components, the parameters of different power conversion circuits vary during actual operation, resulting in uneven output power of each power conversion circuit, which can cause component failure or even damage the circuit in severe cases. Summary of the invention

[0003] In view of this, the present application provides a control method for a power conversion circuit, a power conversion device and an energy storage device, which can solve the problem of unbalanced output power of multiple connected power conversion circuits in the prior art.

[0004] The first aspect of the present application provides a control method for a power conversion circuit, wherein N power conversion circuits are connected, N is a positive integer greater than or equal to 2, and the control method comprises: obtaining actual output parameters of the N power conversion circuits; obtaining reference parameters according to the actual output parameters of the N power conversion circuits; obtaining initial adjustment parameters of the N power conversion circuits according to the difference between the actual output parameters of the N power conversion circuits and the reference parameters; wherein the difference is positively correlated with the initial adjustment parameters; obtaining target adjustment parameters of the N power conversion circuits according to the N initial adjustment parameters, the actual output parameters of the N power conversion circuits and the set reference parameters; and generating a control signal according to the N target adjustment parameters, the control signal being used to control the target output parameters of the N power conversion circuits so as to balance the output power of the N power conversion circuits.

[0005] In one embodiment, the actual output parameter includes at least one of a first actual output parameter and a second actual output parameter. Wherein, when the output terminals of N power conversion circuits are connected in series, obtaining the reference parameter according to the actual output parameters of the N power conversion circuits includes: obtaining the reference parameter according to the first actual output parameter of the N power conversion circuits, wherein the first actual output parameter is the actual output voltage. Alternatively, when the output terminals of the N power conversion circuits are connected in parallel, obtaining the reference parameter according to the actual output parameters of the N power conversion circuits includes: obtaining the reference parameter according to the second actual output parameter of the N power conversion circuits, wherein the second actual output parameter is the actual output current.

[0006] In one embodiment, when the output ends of N power conversion circuits are connected in series, the target output parameter is the actual output voltage. Accordingly, a control signal is generated according to N target adjustment parameters, and the control signal is used to control the target output parameters of the N power conversion circuits so that the output power of the N power conversion circuits is balanced. The process includes: generating a voltage-sharing control signal according to the N target adjustment parameters, and the voltage-sharing control signal is used to control the actual output voltage of the N power conversion circuits so that the output power of the N power conversion circuits is balanced. Alternatively, when the output ends of the N power conversion circuits are connected in parallel, the target output parameter is the actual output current. Accordingly, a control signal is generated according to the N target adjustment parameters, and the control signal is used to control the target output parameters of the N power conversion circuits so that the output power of the N power conversion circuits is balanced. The process includes: generating a current-sharing control signal according to the N target adjustment parameters, and the current-sharing control signal is used to control the actual output current of the N power conversion circuits so that the output power of the N power conversion circuits is balanced.

[0007] In one embodiment, according to N initial adjustment parameters, actual output parameters of N power conversion circuits and set reference parameters, target adjustment parameters of N power conversion circuits are obtained, including: multiplying the N initial adjustment parameters by preset proportional parameters respectively to obtain adjustment values ​​of N power conversion circuits; subtracting the adjustment value of each power conversion circuit from the first actual output parameter of the corresponding power conversion circuit and then adding the result to the reference parameter to obtain the target adjustment parameter of the corresponding power conversion circuit; wherein the types of the target adjustment parameter and the reference parameter are the same as the types of the first actual output parameter. Alternatively, subtracting the adjustment value of each power conversion circuit from the second actual output parameter of the corresponding power conversion circuit and then adding the result to the reference parameter to obtain the target adjustment parameter of the corresponding power conversion circuit; wherein the types of the target adjustment parameter and the reference parameter are the same as the types of the second actual output parameter.

[0008] In one embodiment, the reference parameter is a target adjustment parameter in a historical working cycle.

[0009] In one embodiment, the reference parameter is greater than M actual output parameters, where M is a positive integer less than N.

[0010] In one embodiment, a reference parameter is obtained based on actual output parameters of N power conversion circuits, including: taking the maximum value among the actual output parameters of the N power conversion circuits to obtain the reference parameter; or, calculating the average of the actual output parameters of the N power conversion circuits to obtain the reference parameter.

[0011] In one embodiment, a control signal is generated according to N target adjustment parameters, including: performing deviation processing on the target adjustment parameters of N power conversion circuits to obtain control parameters corresponding to the N power conversion circuits; the control parameters each include at least one of a duty cycle and a frequency; and generating a control signal according to the control parameters corresponding to the N power conversion circuits.

[0012] In one embodiment, a power conversion circuit has a low voltage side and a high voltage side; obtaining actual output parameters of N power conversion circuits includes: obtaining actual output parameters on the low voltage side when the power conversion circuit is running forward; or obtaining actual output parameters on the high voltage side when the power conversion circuit is running reversely; wherein forward operation means that the power conversion circuit transfers energy from the high voltage side to the low voltage side, and reverse operation means that the power conversion circuit transfers energy from the low voltage side to the high voltage side.

[0013] In one embodiment, obtaining actual output parameters of N power conversion circuits includes: obtaining instantaneous values ​​of the actual output parameters of the N power conversion circuits; averaging the instantaneous values ​​of the N power conversion circuits within at least one working cycle to obtain average values ​​of the N actual output parameters; and using the N average values ​​as the actual output parameters of the N power conversion circuits.

[0014] A second aspect of the present application provides a power conversion device, which includes a controller and N power conversion circuits, the N power conversion circuits are connected, and N is a positive integer greater than or equal to 2; the controller is connected to the N power conversion circuits, and is used to: obtain initial adjustment parameters of the N power conversion circuits based on the difference between actual output parameters of the N power conversion circuits and reference parameters; wherein the difference is positively correlated with the initial adjustment parameters; obtain target adjustment parameters of the N power conversion circuits based on the N initial adjustment parameters, the actual output parameters of the N power conversion circuits and the set reference parameters; and control the target output parameters of the N power conversion circuits based on the N target adjustment parameters to balance the output power of the N power conversion circuits.

[0015] In one embodiment, the actual output parameter includes at least one of a first actual output parameter and a second actual output parameter. When the output terminals of N power conversion circuits are connected in series, the controller is used to: obtain the initial adjustment parameters of the N power conversion circuits according to the difference between the first actual output parameters of the N power conversion circuits and the reference parameters; obtain the target adjustment parameters of the N power conversion circuits according to the N initial adjustment parameters, the first actual output parameters of the N power conversion circuits and the set reference parameters; or obtain the target adjustment parameters of the N power conversion circuits according to the initial adjustment parameters, the second actual output parameters of the N power conversion circuits and the set reference parameters; wherein the first actual output parameter is the actual output voltage, the second actual output parameter is the actual output current, the control signal is the voltage-sharing control signal, and the target output parameter is the actual output voltage. Alternatively, when the output ends of N power conversion circuits are connected in parallel, the controller is used to: obtain the initial adjustment parameters of the N power conversion circuits based on the difference between the second actual output parameters of the N power conversion circuits and the reference parameters; obtain the target adjustment parameters of the N power conversion circuits based on the N initial adjustment parameters, the first actual output parameters of the N power conversion circuits and the set reference parameters; or obtain the target adjustment parameters of the N power conversion circuits based on the initial adjustment parameters, the second actual output parameters of the N power conversion circuits and the set reference parameters; wherein the first actual output parameter is the actual output voltage, the second actual output parameter is the actual output current, the control signal is a current sharing control signal, and the target output parameter is the actual output current.

[0016] In one embodiment, the power conversion circuit includes at least one of a resonant conversion circuit, a BUCK circuit, a BOOST circuit, a BUCK-BOOST circuit, a dual active bridge conversion circuit, a forward conversion circuit, and a flyback conversion circuit.

[0017] In one embodiment, the power conversion circuit is a resonant conversion circuit, including: a primary bridge circuit, a resonant network, a transformer and a secondary bridge circuit, the primary bridge circuit is connected to the primary side of the transformer through the resonant network, and the secondary bridge circuit is connected to the secondary side of the transformer; wherein the primary bridge circuit includes at least two primary bridge arms, the secondary bridge circuit includes at least two secondary bridge arms, the two ends of at least two primary bridge arms form the high voltage side of the power conversion circuit, and the two ends of at least two secondary bridge arms form the low voltage side of the power conversion circuit; each primary bridge arm and / or each secondary bridge arm includes a switching tube, and the resonant network includes a resonant inductor and a resonant capacitor.

[0018] The third aspect of the present application provides an energy storage device, which includes an energy storage battery and a power conversion device as described in the second aspect or any one of the embodiments of the second aspect. The energy storage battery is connected to the power conversion device and is used to supply power to the power conversion device or be charged by the power conversion device.

[0019] In one embodiment, the energy storage device further includes an energy storage converter, the energy storage converter is connected to the high voltage side of the power conversion device, and the energy storage battery is connected to the low voltage side of the power conversion device.

[0020] Compared with the prior art, this application has at least the following advantages:

[0021] 1. The control method of the power conversion circuit of the present application can effectively adjust the output parameters of multiple connected power conversion circuits so that the output power of the multiple power conversion circuits is balanced, avoiding current imbalance or voltage imbalance caused by parameter differences of different power conversion circuits, thereby leading to output power imbalance. Therefore, it can effectively avoid the generation of ripples, protect components and circuits, and improve the safety of components and circuits.

[0022] 2. The control method of the power conversion circuit of the present application can be applied to the scenario where the output ends of N power conversion circuits are connected in parallel or in series, can be applied to circuits that operate in one direction or two directions, and can be applied to any type of DC-DC conversion circuit, wherein the N power conversion circuits of IPOP can be controlled for current balancing, and the N power conversion circuits of IPOS can be controlled for voltage balancing, and the current loop or voltage loop can be flexibly selected to achieve regulation according to actual conditions. It can be seen that the control method of the power conversion circuit of the present application has a wide range of adaptability, high control compatibility and flexibility, and low control complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a power conversion device provided in an embodiment of the present application.

[0024] Figure 2 This is a schematic diagram showing that the input terminals and output terminals of N power conversion circuits provided in an embodiment of the present application are connected in parallel.

[0025] Figure 3 This is a circuit diagram of two power conversion circuits connected in parallel provided by an embodiment of the present application.

[0026] Figure 4 This is a circuit diagram of two power conversion circuits connected in parallel provided by another embodiment of the present application.

[0027] Figure 5 It is a schematic diagram of N power conversion circuits provided in an embodiment of the present application, in which input ends are connected in parallel and output ends are connected in series.

[0028] Figure 6 It is a flow chart of a control method of a power conversion circuit provided in an embodiment of the present application.

[0029] 7A to 7D When the output terminals of two power conversion circuits are connected in parallel Figure 4 Control block diagram of the method shown.

[0030] Fig. 8A and Figure 8B When the output terminals of two power conversion circuits are connected in series Figure 4 Control block diagram of the method shown.

[0031] Fig. 9 yes Figure 3 A simulation waveform diagram of the circuit shown when it is running in the forward direction without using the method of the embodiment of the present application.

[0032] Fig.10 yes Figure 3 The circuit shown is a simulation waveform diagram using the method of an embodiment of the present application when running in the forward direction.

[0033] Fig.11 It is a schematic diagram of an energy storage device provided in an embodiment of the present application.

[0034] Main component symbols

[0035] Power converter 100

[0036] Power conversion circuit 10, 11, 12, 13, 14

[0037] Primary Bridge Circuit 101

[0038] Resonant Network 102

[0039] Secondary bridge circuit 103

[0040] Controller 200

[0041] Power conversion device 300

[0042] Energy storage battery 400

[0043] Energy Storage Converter 500

[0044] Energy storage equipment 1000 DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application. In the absence of conflict, the following different embodiments and features in the embodiments can be combined with each other.

[0046] See also Figure 1 , shows a block diagram of a power converter 100 provided in an embodiment of the present application. The power converter 100 can be applied to energy storage power supply, charging station, server power supply, vehicle power supply and other fields.

[0047] like Figure 1 As shown, the power converter 100 includes N power conversion circuits 10 (corresponding to Figure 1 , . . . , power conversion circuit N). N is a positive integer greater than or equal to 2. The N power conversion circuits 10 have the same structure and are connected. The power converter 100 is connected to the controller 200. The controller 200 is used to control the output power balance of the N power conversion circuits 10, that is, the output power of the N power conversion circuits 10 is the same.

[0048] The controller 200 may be a microcontroller (MCU), a digital signal processor (DSP), or other components or circuits with control or processing functions.

[0049] In one embodiment, please refer to Figure 2 , the input sides of the N power conversion circuits 10 can be connected in parallel, and the output sides of the N power conversion circuits 10 can be connected in parallel. That is, the N power conversion circuits 10 can be connected in an input parallel output parallel (IPOP) manner. One of the input side and the output side of each power conversion circuit 10 is a high voltage side, and the other is a low voltage side.

[0050] It can be understood that when the input side is the high voltage side and the output side is the low voltage side, the high voltage side of each power conversion circuit 10 can be connected to the power supply, and the low voltage side can be connected to the load. Each power conversion circuit 10 is connected to the high voltage side voltage provided by the power supply, converts the high voltage side voltage into the low voltage side voltage and outputs it to the load, and the low voltage side voltage is less than the high voltage side voltage. In this process, the power conversion circuit 10 transfers energy from the high voltage side to the low voltage side. For the convenience of description, this process can be referred to as the forward operation process of the power conversion circuit 10.

[0051] When the input side is the low voltage side and the output side is the high voltage side, the low voltage side of each power conversion circuit 10 can be connected to a power supply, and the high voltage side can be connected to a load. The low voltage side of each power conversion circuit 10 can be connected to the low voltage side voltage provided by the power supply, and the low voltage side voltage is converted into a high voltage side voltage and output to the load. In this process, the power conversion circuit 10 transfers energy from the low voltage side to the high voltage side. For ease of description, this process can be referred to as the reverse operation process of the power conversion circuit 10. It should be understood that in other embodiments, the forward and reverse directions can also be reversed.

[0052] in, Figure 2 The first power conversion circuit 10 (ie Figure 2 The current I flows through the high voltage side of the power conversion circuit 1) HV1 , a voltage V is generated on the high voltage side HV1 , a current I flows through the low voltage side LV1 , a voltage V is generated on the low voltage side LV1 . Figure 2 The Nth power conversion circuit 10 (i.e. Figure 2 The current I flows through the high voltage side of the power conversion circuit N) in HVN , a voltage V is generated on the high voltage side HVN , a current I flows through the low voltage side LVN , a voltage V is generated on the low voltage side LVN .

[0053] In some embodiments, the power conversion circuit 10 may be a unidirectional circuit capable of forward or reverse operation. In other embodiments, the power conversion circuit 10 may be a bidirectional circuit capable of both forward and reverse operation.

[0054] In the embodiment of the present application, the power conversion circuit 10 is a DC-DC conversion circuit, and the corresponding circuit topology can be selected according to actual needs, for example, it can be at least one of a resonant conversion circuit, a BUCK circuit, a BOOST circuit, a BUCK-BOOST circuit, a dual active bridge (DAB) conversion circuit, a forward conversion circuit, a flyback conversion circuit, etc. Among them, the resonant conversion circuit can be, for example, a three-phase resonant conversion circuit or a single-phase resonant conversion circuit.

[0055] For example, Figure 3 A circuit diagram of a power conversion circuit 10 connected in parallel (ie, using an IPOP connection method) is shown, wherein the power conversion circuit 10 is a three-phase resonant conversion circuit, and N=2.

[0056] like Figure 3 As shown, the two three-phase resonant conversion circuits 11 and 12 each include: a primary bridge circuit 101, three resonant networks 102, three transformers and a secondary bridge circuit 103, wherein the primary bridge circuit 101 includes three primary bridge arms, the secondary bridge circuit 103 includes three secondary bridge arms, and the three primary bridge arms, the three resonant networks 102, the three transformers and the three secondary bridge arms correspond one to one.

[0057] Specifically, in the three-phase resonant conversion circuit 11, each primary bridge arm includes two switch tubes connected in series (such as Q1 and Q2, or Q3 and Q4, or Q5 and Q6), and each secondary bridge arm includes two switch tubes connected in series (such as S1 and S2, or S3 and S4, or S5 and S6). The switch tube can adopt any semiconductor power tube according to actual conditions. The control end of each switch tube is connected to the controller 200, and the switch tube is turned on or off under the control signal of the controller 200. Each resonant network 102 includes a resonant capacitor (such as C rA1 , C rB1 or C rC1 ), resonant inductor (such as L rA1 , L rB1 or L rC1 ) and magnetizing inductance (such as L mA1 , L mB1 or L mC1 In a resonant network 102, the resonant inductor and the resonant capacitor are connected in series, and the excitation inductor is connected in parallel to a corresponding transformer (such as T A1 , T B1 or T C1 ) so that the resonant network 102 forms an LLC topology. The midpoint of each primary bridge arm (such as point a, point b or point c) is connected to the first end of the primary side of a corresponding transformer through a corresponding resonant inductor and a resonant capacitor, and the first end of the secondary side of the transformer is connected to the midpoint of a corresponding secondary bridge arm (such as point d, point e or point f). The second ends of the primary sides of the three transformers are connected together, and the second ends of the secondary sides of the three transformers are connected together, so that the three transformers form a Y-type (i.e., star-type) connection. In this way, the three-phase resonant conversion circuit 11 forms a bidirectional three-phase interleaved LLC resonant circuit topology.

[0058] Similarly, in the three-phase resonant conversion circuit 12, each primary bridge arm includes two switch tubes connected in series (such as Q7 and Q8, or Q9 and Q10, or Q11 and Q12), each secondary bridge arm includes two switch tubes connected in series (such as S7 and S8, or S9 and S10, or S11 and S12), and the control end of each switch tube is connected to the controller 200, and the switch tube is turned on or off under the control signal of the controller 200. Each resonant network 102 includes a resonant capacitor (such as C rA2 , C rB2 or C rC2 ), resonant inductor (such as L rA2 , L rB2 or L rC2 ) and magnetizing inductance (such as L mA2 , L mB2 or L mC2In a resonant network 102, the resonant inductor and the resonant capacitor are connected in series, and the excitation inductor is connected in parallel to a corresponding transformer (such as T A2 , T B2 or T C2 ) so that the resonant network 102 forms an LLC topology. The midpoint of each primary bridge arm (such as point g, point h or point i) is connected to the first end of the primary side of a corresponding transformer through a corresponding resonant inductor and a resonant capacitor, and the first end of the secondary side of the transformer is connected to the midpoint of a corresponding secondary bridge arm (such as point j, point k or point l). The second ends of the primary sides of the three transformers are connected together, and the second ends of the secondary sides of the three transformers are connected together, so that the three transformers form a Y-type (i.e., star-type) connection. In this way, the three-phase resonant conversion circuit 12 also forms a bidirectional three-phase interleaved LLC resonant circuit topology.

[0059] Both ends of each primary bridge arm of the three-phase resonant conversion circuit 11 and 12 are connected in parallel with the capacitor C1 to form a high voltage side. Both ends of each secondary bridge arm of the three-phase resonant conversion circuit 11 and 12 are connected in parallel with the capacitor C2 to form a low voltage side.

[0060] Based on such a design, when the three-phase resonant conversion circuits 11 and 12 are running in the forward direction, the primary bridge circuit 101 constitutes a three-phase inverter circuit, and the secondary bridge circuit 103 constitutes a three-phase rectifier circuit.

[0061] Each primary bridge arm and its connected resonant network 102, transformer and secondary bridge arm correspond to one of the three phases A, B and C. There is a 120° phase difference between the control signals of the switch tubes corresponding to each other in the three phases. Figure 3 As shown, the high-voltage side input current I of the three-phase resonant conversion circuit 11 HV1 , low voltage side output current I LV1 , the primary sides of the three transformers are respectively connected by a corresponding primary current (such as I pA1 or I pB1 or I pC1 ), there is also a 120° phase difference between the three-phase primary currents. Similarly, the high-voltage side input current I HV2 , low voltage side output current I LV2 , the primary sides of the three transformers are respectively connected by a corresponding primary current (such as I pA2 or I pB2 or I pC2 ), there is also a 120° phase difference between the three-phase primary currents. The transformer plays the role of isolating the primary bridge circuit 101 and the secondary bridge circuit 103 and converting the voltage ratio. Among them, the transformer adopts a Y-type connection method to enable electrical coupling between the three phases, which can reduce the adverse effects caused by the parameter differences between the phases, thereby improving the current sharing capability.

[0062] During the operation of the primary bridge circuit 101, two switch tubes in the same primary bridge arm are complementary to each other, and three switch tubes in the three primary bridge arms are simultaneously turned on. For example, an upper switch tube in one primary bridge arm and lower switch tubes in the other two primary bridge arms may be simultaneously turned on, or upper switch tubes in two primary bridge arms and lower switch tube in the remaining primary bridge arm may be simultaneously turned on. The operation process of the secondary bridge circuit 103 is similar, so it will not be described again here.

[0063] It can be understood that the resonant network 102 determines the resonant frequency fr of the power conversion circuit 10. The switches in the primary bridge arm and the secondary bridge arm of the resonant conversion circuit 11 are switched on and off at a high frequency with a switching frequency fs1 equal to the resonant frequency fr or close to the resonant frequency fr, and the switches in the primary bridge arm and the secondary bridge arm of the resonant conversion circuit 12 are switched on and off at a high frequency with a switching frequency fs2 equal to the resonant frequency fr or close to the resonant frequency fr. It can be understood that since the resonant network 102 is connected to the primary side of the transformer, the primary current is also the current of the resonant network 102.

[0064] When the three-phase resonant conversion circuits 11 and 12 operate in reverse, the primary bridge circuit 101 constitutes a three-phase rectifier circuit, and the secondary bridge circuit 103 constitutes a three-phase inverter circuit. The process is the reverse process of the forward operation. For details, please refer to the forward operation, so it will not be repeated here.

[0065] It should be understood that in some other embodiments, the excitation inductor can also be integrated in the corresponding transformer. Alternatively, the transformers can also be connected in a triangle, or they can be independent of each other and not connected to each other. Alternatively, the resonant network 102 can also adopt other topological structures, such as an LCC topological structure. Alternatively, the two ends of the primary bridge arm can form a low-voltage side, and the two ends of the secondary bridge arm can form a high-voltage side. Alternatively, the switch tube in the primary bridge circuit 101 or the secondary bridge circuit 103 can be replaced with a diode, so that the three-phase resonant conversion circuit 11 and the three-phase resonant conversion circuit 12 are both unidirectional circuits. The specific selection can be made according to actual needs, and this application does not limit this.

[0066] Another example, Figure 4 Another circuit diagram of a power conversion circuit 10 in parallel is shown, wherein the power conversion circuit 10 is a single-phase resonant conversion circuit, and N=2.

[0067] like Figure 4 As shown, the two single-phase resonant conversion circuits 13 and 14 each include: a primary bridge circuit 101, a resonant network 102, a transformer and a secondary bridge circuit 103, wherein the primary bridge circuit 101 includes two primary bridge arms, and the secondary bridge circuit 103 includes two secondary bridge arms.

[0068] Specifically, in the single-phase resonant conversion circuit 13, each primary bridge arm includes two switch tubes connected in series (such as Q1 and Q2, or Q3 and Q4), and each secondary bridge arm includes two switch tubes connected in series (such as S1 and S2, or S3 and S4). Therefore, the primary bridge circuit 101 and the secondary bridge circuit 103 are both full-bridge topology structures. The switch tube can adopt any semiconductor power tube according to actual conditions. The control end of each switch tube is connected to the controller 200, and the switch tube is turned on or off under the control signal of the controller 200. The resonant network 102 includes a resonant inductor C r1 , resonant capacitor L r1 and the magnetizing inductance L m1 , resonant inductor C r1 , resonant capacitor L r1 and the magnetizing inductance L m1 The connection relationship can be found in Figure 3 The midpoints of the two primary bridge arms are connected through the corresponding resonant inductor Cr1 and resonant capacitor L r1 The two ends of the primary side of the transformer T1 are connected to the middle points of the two secondary bridge arms. In this way, the single-phase resonant conversion circuit 13 forms a bidirectional full-bridge LLC resonant circuit topology.

[0069] In the single-phase resonant conversion circuit 14, each primary bridge arm includes two switch tubes connected in series (such as Q5 and Q6, or Q7 and Q8), and each secondary bridge arm includes two switch tubes connected in series (such as S5 and S6, or S7 and S8). Therefore, the primary bridge circuit 101 and the secondary bridge circuit 103 are both full-bridge topology structures. The control end of each switch tube is connected to the controller 200, and the switch tube is turned on or off under the control signal of the controller 200. The resonant network 102 includes a resonant inductor C r2 , resonant capacitor L r2 and the magnetizing inductance L m2 , resonant inductor C r2 , resonant capacitor L r2 and the magnetizing inductance L m2 The connection relationship can be found in Figure 3 The midpoints of the two primary bridge arms are connected through the corresponding resonant inductor C r2 and resonant capacitor L r2 The two ends of the primary side of the transformer T2 are connected to the middle points of the two secondary bridge arms. In this way, the single-phase resonant conversion circuit 14 also forms a bidirectional full-bridge LLC resonant circuit topology.

[0070] Both ends of each primary bridge arm of the resonant conversion circuit 13 and 14 are connected in parallel with the capacitor C1 to form a high voltage side. Both ends of each secondary bridge arm of the three-phase resonant conversion circuit 13 and 14 are connected in parallel with the capacitor C2 to form a low voltage side.

[0071] Based on such a design, when the resonant conversion circuits 13 and 14 are running forward, the primary bridge circuit 101 constitutes an inverter circuit, and the secondary bridge circuit 103 constitutes a rectifier circuit. When the resonant conversion circuits 13 and 14 are running reversely, the primary bridge circuit 101 constitutes a rectifier circuit, and the secondary bridge circuit 103 constitutes an inverter circuit. The two switch tubes in the same primary bridge arm are complementary turned on, and the two switch tubes in the same secondary bridge arm are complementary turned on. The transformer plays the role of isolating the primary bridge circuit 101 and the secondary bridge circuit 103 and converting the voltage ratio.

[0072] It can be understood that the resonant network 102 determines the resonant frequency fr of the power conversion circuit 10. The switches in the primary bridge arm and the secondary bridge arm of the resonant conversion circuit 13 are switched on and off at a high frequency with a switching frequency fs1 equal to the resonant frequency fr or close to the resonant frequency fr, and the switches in the primary bridge arm and the secondary bridge arm of the resonant conversion circuit 14 are switched on and off at a high frequency with a switching frequency fs2 equal to the resonant frequency fr or close to the resonant frequency fr. It can be understood that since the resonant network 102 is connected to the primary side of the transformer, the primary current is also the current of the resonant network 102.

[0073] It should be understood that in some other embodiments, the excitation inductance L m1 It can also be integrated in transformer T1, the excitation inductance L m2 It can also be integrated in the transformer T2. Alternatively, the resonant network 102 can also adopt other topological structures, such as LCC topological structure, etc. Alternatively, the two ends of the primary bridge arm can form a low-voltage side, and the two ends of the secondary bridge arm can form a high-voltage side. Alternatively, some of the switching tubes in the primary bridge circuit 101 or the secondary bridge circuit 103 can be replaced with capacitors, so that the primary bridge circuit 101 or the secondary bridge circuit 103 of the resonant conversion circuit 13 and 14 is a half-bridge topology. The specific selection can be made according to actual needs, and this application does not limit this.

[0074] In another embodiment, see Figure 5 , the output sides of the N power conversion circuits 10 can be connected in series, and the input sides of the N power conversion circuits 10 can be connected in parallel. That is to say, the N power conversion circuits 10 can be connected in an input parallel output series (IPOS) manner. One of the input side and the output side of each power conversion circuit 10 is a high voltage side, and the other is a low voltage side. The power conversion circuit 10 can be a unidirectional circuit or a bidirectional circuit.

[0075] in, Figure 5 The first power conversion circuit 10 (ie Figure 5 The current I flows through the high voltage side of the power conversion circuit 1) HV1 , a voltage V is generated on the high voltage side HV , a current I flows through the low voltage side LV , a voltage V is generated on the low voltage side LV1 . Figure 5 The Nth power conversion circuit 10 (i.e. Figure 5 The current I flows through the high voltage side of the power conversion circuit N) in HVN , a voltage V is generated on the high voltage side HV , a current I flows through the low voltage side LV , a voltage V is generated on the low voltage side LVN .

[0076] It should be understood that Figure 5 For other descriptions of the embodiments, please refer to the previous Figures 2 to 4 The relevant contents in the embodiments will not be repeated here.

[0077] It can be understood that, ideally, the parameters of the N connected power conversion circuits 10 are the same, the output current and the output voltage are balanced (or the same), so that the output power is balanced (or the same). However, in reality, due to manufacturing errors and tolerance design of circuit components, in actual operation, the parameters of different power conversion circuits 10 are different, resulting in unbalanced output currents or unbalanced output voltages of the power conversion circuits 10, thereby causing unbalanced output power.

[0078] For example, ideally, the resonant frequency fr of the parallel or series resonant conversion circuits is the same. But in reality, the actual resonant frequencies of different resonant conversion circuits will be different. When operating at the same switching frequency, the impedance and gain of different resonant conversion circuits will differ greatly, resulting in an unbalanced output current of each resonant conversion circuit in parallel, or an unbalanced output voltage of each resonant conversion circuit in series. In the case of an unbalanced output current of each resonant conversion circuit in parallel, the output power of each resonant conversion circuit in parallel cannot be balanced. In the case of an unbalanced output voltage of each resonant conversion circuit in series, the output power of each resonant conversion circuit in series cannot be balanced.

[0079] Alternatively, when the resonant frequencies fr are the same and they operate at the same switching frequency, the impedances and gains of different resonant conversion circuits may differ greatly due to differences in the parasitic parameters of the components, resulting in an unbalanced output current of each resonant conversion circuit in parallel or an unbalanced output voltage of each resonant conversion circuit in series, and thus, the output power cannot be balanced.

[0080] Among them, unbalanced output current will cause current ripple, and even lead to over-current stress of components or circuits. Unbalanced output voltage will cause voltage ripple, and even lead to over-voltage stress of components or circuits. Therefore, in general, unbalanced output power will cause the risk of overstress of the circuit, and in severe cases, it will cause component failure or even damage the circuit.

[0081] In this regard, the controller 200 of the embodiment of the present application can be used to execute the control method of the power conversion circuit provided in the embodiment of the present application to achieve balanced control of N power conversion circuits 10, so that the output power of the N power conversion circuits 10 is balanced, thereby protecting components and ensuring the normal operation of the power conversion circuits 10.

[0082] Combine the following Figures 6 to 8B The control method of the power conversion circuit provided in the embodiment of the present application is described in detail. Figure 6 A flow chart of a control method for a power conversion circuit according to an embodiment of the present application is shown. 7A to 7D The control loop diagrams of the method of the embodiment of the present application are respectively shown when N (N=2) power conversion circuits in the power converter adopt an IPOP connection mode. Fig. 8A and Figure 8B The control loop diagrams of the method of the embodiment of the present application are respectively shown when N (N=2) power conversion circuits in the power converter adopt the IPOS connection mode.

[0083] like Figure 6 As shown, the control method of the power conversion circuit includes:

[0084] Step S10: Acquire actual output parameters of N power conversion circuits.

[0085] The actual output parameter includes at least one of a first actual output parameter and a second actual output parameter, and a type of the first actual output parameter is different from a type of the second actual output parameter.

[0086] For example, in this embodiment, the first actual output parameter is the actual output voltage, and the second actual output parameter is the actual output current. When the output terminals of the N power conversion circuits 10 are connected in series, the actual output parameters include at least the first actual output parameter. When the output terminals of the N power conversion circuits 10 are connected in parallel, the actual output parameters include at least the second actual output parameter.

[0087] For further example, when the output ends of the power conversion circuits 10 are connected in parallel and the N power conversion circuits 10 are running in the forward direction, the low-voltage side of the N power conversion circuits 10 is the output side, so step S10 is to obtain the actual output current I on the low-voltage side of the N power conversion circuits 10. LV1 ,……,I LVN, or to obtain the actual output current I on the low voltage side LV1 ,……,I LVN and the actual output voltage V LV1 ,……,V LVN .

[0088] When the output ends of the power conversion circuits 10 are connected in parallel and the N power conversion circuits 10 are running in reverse, the high-voltage side of the N power conversion circuits 10 is the output side. Therefore, step S10 is to obtain the actual output current I on the high-voltage side of the N power conversion circuits 10. HV1 ,……,I HVN , or obtain the actual output current I on the high voltage side HV1 ,……,I HVN and the actual output voltage V HV1 ,……,V HVN .

[0089] When the output ends of the N power conversion circuits 10 are connected in series and the N power conversion circuits 10 are running in the forward direction, the low-voltage side of the N power conversion circuits 10 is the output side. Therefore, step S10 is to obtain the actual output voltage V on the low-voltage side of the N power conversion circuits 10. LV1 ,……,V LVN , or to obtain the actual output voltage V on the low voltage side LV1 ,……,V LVN and the actual output current I LV1 ,……,I LVN .

[0090] In one embodiment, the actual output parameter is an average value. Therefore, step S10 may include the following sub-steps:

[0091] Step S101: Acquire instantaneous values ​​of actual output parameters of N power conversion circuits.

[0092] Step S102: averaging the instantaneous values ​​of the N power conversion circuits in at least one working cycle to obtain average values ​​of the N actual output parameters.

[0093] The duty cycle here refers to the duty cycle of the power conversion circuit 10. Calculating the average value can reduce sampling errors and reduce deviations caused by parameter fluctuations, and obtain a relatively stable current value, which is beneficial to the subsequent control effect of the controller 200 on the circuit 10.

[0094] Step S103: taking the N average values ​​as actual output parameters of the N power conversion circuits.

[0095] Among them, in the above step S101, the controller 200 can perform real-time sampling of the actual output voltage of each power conversion circuit 10 through a voltage sampling circuit to obtain the instantaneous value of the first actual output parameter of each power conversion circuit 10. The controller 200 can perform real-time sampling of the actual output current of each power conversion circuit 10 through a current sampling circuit to obtain the instantaneous value of the second actual output parameter of each power conversion circuit 10. Furthermore, the first actual output parameter and the second actual output parameter calculated by the controller 200 are both average values.

[0096] Step S20: Obtaining reference parameters according to actual output parameters of the N power conversion circuits.

[0097] Specifically, when the output terminals of N power conversion circuits 10 are connected in series, step S20 may be: obtaining the reference parameter according to the first actual output parameters (ie, the actual output voltage) of the N power conversion circuits.

[0098] When the output ends of N power conversion circuits 10 are connected in parallel, step S20 may be: obtaining the reference parameter according to the second actual output parameters (ie, the actual output current) of the N power conversion circuits.

[0099] Among them, the first actual output parameter or the second actual output parameter of the N power conversion circuits 10 can be subjected to mathematical operation processing to obtain the reference parameter. The mathematical operation processing can be, for example, taking the maximum value, calculating the mean value, or calculating the weighted average, etc., which is not limited here. The type of the reference parameter is the same as the type of the actual output parameter, and the reference parameter is greater than the M actual output parameters, M is a positive integer less than N, and its specific size can be set accordingly according to the actual situation.

[0100] For example, in a scenario where the output ends of N power conversion circuits 10 are connected in parallel, 7A to 7D As shown, the controller 200 can obtain the reference current I by taking the maximum value among the actual output currents of the N power conversion circuits 10. Max At this time, M=N-1, the reference current I Max Alternatively, in some other embodiments, the controller 200 may average the actual output currents of the N power conversion circuits 10 to obtain the reference current.

[0101] In the scenario where the output ends of N power conversion circuits 10 are connected in series, such as Fig. 8A and Figure 8B As shown, the controller 200 can obtain the reference voltage V by taking the maximum value among the actual output voltages of the N power conversion circuits 10. Max At this time, M=N-1, the reference voltage V MaxAlternatively, in some other embodiments, the controller 200 may average the actual output voltages of the N power conversion circuits 10 to obtain the reference voltage.

[0102] In addition, in one embodiment, if 7A to 7D , Fig. 8A and Figure 8B As shown, the actual output parameters of the N power conversion circuits 10 may be filtered first, and then the actual output parameters of the N power conversion circuits 10 after filtering may be mathematically processed to obtain the reference parameters. The filtering process may be, for example, low-pass filtering through a low-pass filter (LPF) or other types of filtering processes.

[0103] It should be understood that the above-described method of obtaining the reference parameters based on the actual output parameters of N power conversion circuits is only an illustrative example provided in this application, which can be specifically set according to actual conditions and is not limited to the implementation method mentioned in this application.

[0104] Step S30: obtaining initial adjustment parameters of the N power conversion circuits according to the difference between the actual output parameters of the N power conversion circuits and the reference parameters.

[0105] The type of the initial adjustment parameter is the same as the type of the actual output parameter. Moreover, the difference is positively correlated with the initial adjustment parameter. For example, when the difference is 0, the initial adjustment parameter is 0 or a smaller value. When the difference is greater than 0, the initial adjustment parameter is greater than 0 or a larger value.

[0106] In some embodiments, the actual output parameters of the N power conversion circuits 10 can be subtracted from the reference parameters to obtain the difference between the N power conversion circuits 10, and then the difference between the N power conversion circuits 10 can be directly used as the initial adjustment parameters of the N power conversion circuits 10.

[0107] For example, Fig. 7A and Figure 7C As shown, in the scenario where the output ends of the two power conversion circuits 10 are connected in parallel and the two power conversion circuits 10 are running in the forward direction, the initial adjustment parameters of the two power conversion circuits 10 are I LV1 -I Max , I LV2 -I Max .

[0108] For example, Figure 7B and Fig.7D As shown, in the scenario where the output ends of the two power conversion circuits 10 are connected in parallel and the two power conversion circuits 10 are running in reverse, the initial adjustment parameters of the two power conversion circuits 10 are I HV1 -I Max , IHV2 -I Max .

[0109] For example, Fig. 8A and Figure 8B As shown, in the scenario where the output ends of the two power conversion circuits 10 are connected in series and the two power conversion circuits 10 are running in the forward direction, the initial adjustment parameters of the two power conversion circuits 10 are V LV1 -V Max , V LV2 -V Max .

[0110] In one embodiment, the difference may be taken as an absolute value and then used as the initial adjustment parameter. In another embodiment, the difference may be multiplied by a set multiple to obtain the initial adjustment parameter.

[0111] Step S40: Obtaining target adjustment parameters of the N power conversion circuits according to the N initial adjustment parameters, the actual output parameters of the N power conversion circuits and the set reference parameters.

[0112] Specifically, in step S40 , mathematical operations may be performed using the N initial adjustment parameters, the actual output parameters of the N power conversion circuits 10 , and the set reference parameters to obtain target adjustment parameters of the N power conversion circuits 10 .

[0113] For example, in some embodiments, step S40 may include the following sub-steps:

[0114] Step S401: multiplying N initial adjustment parameters by preset ratio parameters respectively to obtain adjustment values ​​of N power conversion circuits.

[0115] Among them, the preset proportional parameters corresponding to different initial adjustment parameters can be the same or different, and the size and positive and negative polarities of the preset proportional parameters can be set accordingly according to actual conditions, which are not limited here.

[0116] For example, in one embodiment, 7A to 8B As shown, the preset proportional parameter k1 is equal to the preset proportional parameter k2, and both k1 and k2 are greater than 1. k1 and k2 are used to perform proportional adjustment on the initial adjustment parameters of the two power conversion circuits 10 .

[0117] Further, such as Fig. 7A and Figure 7C As shown, in the scenario where the output ends of two power conversion circuits 10 are connected in parallel and the two power conversion circuits 10 are running in the forward direction, the adjustment value of one of the power conversion circuits 10 is k1*(I LV1 -I Max ), the adjustment value of the other power conversion circuit 10 is k2*(I LV2 -IMax ).

[0118] For example, Figure 7B and Fig.7D As shown, in the scenario where the output ends of the two power conversion circuits 10 are connected in parallel and the two power conversion circuits 10 are running in reverse, the adjustment value of one of the power conversion circuits 10 is k1*(I HV1 -I Max ), the adjustment value of the power conversion circuit 10 is k2*(I HV2 -I Max ).

[0119] For example, Fig. 8A and Figure 8B As shown, in the scenario where the output ends of two power conversion circuits 10 are connected in series and the two power conversion circuits 10 are running in the forward direction, the adjustment value of one of the power conversion circuits 10 is k1*(V LV1 -V Max ), the adjustment value of the other power conversion circuit 10 is k2*(V LV2 -V Max ).

[0120] Step S402: subtract the adjustment value of each power conversion circuit from the actual output parameter of the corresponding power conversion circuit and then add the result to the reference parameter to obtain target adjustment parameters of the N power conversion circuits.

[0121] In the embodiment of the present application, the target adjustment parameter can be used to adjust the control signal of the power conversion circuit 10 in subsequent steps.

[0122] In step S402, the adjustment value of each power conversion circuit 10 can be subtracted from the first actual output parameter of the corresponding power conversion circuit 10 and then added to the reference parameter to obtain the corresponding target adjustment parameter of the power conversion circuit 10. The types of the target adjustment parameter and the reference parameter at this time are the same as the type of the first actual output parameter. Based on this, it can also be seen that the method of this embodiment is to achieve balanced control of the power conversion circuit 10 through a voltage loop.

[0123] Alternatively, the adjustment value of each power conversion circuit 10 may be subtracted from the corresponding second actual output parameter of the power conversion circuit 10 and then added to the reference parameter to obtain the corresponding target adjustment parameter of the power conversion circuit 10. At this time, the types of the target adjustment parameter and the reference parameter are the same as the types of the second actual output parameter. Based on this, it can be seen that the method of this embodiment is to achieve balanced control of the power conversion circuit 10 through the current loop.

[0124] Among them, the size of the reference parameter can be set accordingly according to the operating conditions. Under different operating conditions, the size and type of the reference parameter set can be different. For example, when the output ends of N power conversion circuits 10 are connected in parallel, the load requires a current of 160A, then the reference parameter is the reference current, and can be set to 160 / N (A, ampere). When the output ends of N power conversion circuits 10 are connected in series, the load requires a voltage of 220V, then the reference parameter is the reference voltage, and can be set to 220 / N (V, volt).

[0125] As a further example, in a scenario where the output ends of two power conversion circuits 10 are connected in parallel and the two power conversion circuits 10 are running in the forward direction,

[0126] like Fig. 7A As shown, the actual output parameter involved in the calculation in step S402 is the second actual output parameter on the low voltage side, and the reference parameter is the reference current I LV_ref Correspondingly, the target adjustment parameter is the target adjustment current, wherein the target adjustment current of a power conversion circuit 10 is k1*(I LV1 -I Max )-I LV1 +I LV_ref , the target regulation current of another power conversion circuit 10 is k2*(I LV2 -I Max )-I LV2 +I LV_ref .

[0127] Or, if Figure 7C As shown, the actual output parameter involved in the calculation in step S402 is the first actual output parameter on the low voltage side, and the reference parameter is the reference voltage V LV_ref Correspondingly, the target adjustment parameter is the target adjustment voltage, wherein the target adjustment voltage of a power conversion circuit 10 is k1*(I LV1 -I Max )-V LV1 +V LV_ref , the target regulation voltage of another power conversion circuit 10 is k2*(I LV2 -I Max )-V LV2 +V LV_ref .

[0128] As another example, in a scenario where the output ends of two power conversion circuits 10 are connected in parallel and the two power conversion circuits 10 operate in reverse,

[0129] like Figure 7B As shown, the actual output parameter involved in the calculation in step S402 is the second actual output parameter on the high voltage side, and the reference parameter is the reference current I HV_refCorrespondingly, the target adjustment parameter is the target adjustment current, wherein the target adjustment current of a power conversion circuit 10 is k1*(I HV1 -I Max )-I HV1 +I HV_ref , the target regulation current of another power conversion circuit 10 is k2*(I HV2 -I Max )-I HV2 +I HV_ref .

[0130] Or, if Fig.7D As shown, the actual output parameter involved in the calculation in step S402 is the first actual output parameter on the high voltage side, and the reference parameter is the reference voltage V HV_ref Correspondingly, the target adjustment parameter is the target adjustment voltage, wherein the target adjustment voltage of a power conversion circuit 10 is k1*(I HV1 -I Max )-V HV1 +V HV_ref , the target regulation voltage of another power conversion circuit 10 is k2*(I HV2 -I Max )-V HV2 +V HV_ref .

[0131] For another example, in a scenario where the output ends of two power conversion circuits 10 are connected in series and the two power conversion circuits 10 are running in the forward direction,

[0132] like Fig. 8A As shown, the actual output parameter involved in the calculation in step S402 is the second actual output parameter on the low voltage side, and the reference parameter is the reference current I LV_ref Correspondingly, the target adjustment parameter is the target adjustment current, wherein the target adjustment current of a power conversion circuit 10 is k1*(V LV1 -V Max )-I LV1 +I LV_ref , the target regulation current of another power conversion circuit 10 is k2*(V LV2 -V Max )-I LV2 +I LV_ref .

[0133] Or, if Figure 8B As shown, the actual output parameter involved in the calculation in step S402 is the first actual output parameter on the low voltage side, and the reference parameter is the reference voltage V LV_ref Correspondingly, the target adjustment parameter is the target adjustment voltage, wherein the target adjustment voltage of a power conversion circuit 10 is k1*(V LV1 -VMax )-V LV1 +V LV_ref , the target regulation voltage of another power conversion circuit 10 is k2*(V LV2 -V Max )-V LV2 +V LV_ref .

[0134] In some embodiments, the set reference parameter can be a target adjustment parameter in a historical working cycle, for example, a target adjustment parameter in a previous working cycle. It can also be seen from this that the control method of the embodiment of the present application is a process of cyclic execution and continuous learning iteration, which can make the actual output parameters of the N power conversion circuits 10 gradually tend to be equal and in a steady state.

[0135] Step S50: generating a control signal according to the N target adjustment parameters, wherein the control signal is used to control the target output parameters of the N power conversion circuits so as to balance the output powers of the N power conversion circuits.

[0136] Specifically, step S50 may include the following sub-steps:

[0137] Step S501: performing deviation processing on target adjustment parameters of N power conversion circuits to obtain control parameters corresponding to the N power conversion circuits.

[0138] The deviation processing may be, for example, PI (Proportion Integration) regulation, PID (Proportion Integration Differentiation) regulation or other regulation processing methods.

[0139] The control parameter may include at least one of a duty cycle and a frequency, which may be flexibly selected according to actual conditions and is not specifically limited here. 7A to 7D , Fig. 8A and Figure 8B As shown, one of the control parameters of the power conversion circuit 10 may be the frequency f s1 and / or duty cycle D1, another control parameter of the power conversion circuit 10 may be the frequency f s2 and / or duty cycle D2.

[0140] Step S502: Generate a control signal according to the control parameters corresponding to the N power conversion circuits. The control signal is used to control the target output parameters of the N power conversion circuits to be the same.

[0141] Among them, for Figure 2In the embodiment shown in which the output ends of N power conversion circuits are connected in parallel, the target output parameter is the actual output current. Accordingly, in this embodiment, the control signal is a current sharing control signal, which is used to control the actual output current of the N power conversion circuits so as to balance the output power of the N power conversion circuits.

[0142] for Figure 5 In the embodiment shown, the output terminals of N power conversion circuits are connected in series, and the target output parameter is the actual output voltage. Accordingly, in this embodiment, the control signal is a voltage balancing control signal, and the voltage balancing control signal is used to control the actual output voltage of the N power conversion circuits so as to balance the output power of the N power conversion circuits.

[0143] In some embodiments, when the control parameter is the frequency f s1 、f s2 When, according to the frequency f s1 、f s2 The generated control signal is a pulse frequency modulation (PFM) control signal. Among them, since pulse frequency modulation has advantages in efficiency and response speed, it is conducive to efficient and rapid control of the power conversion circuit 10 and reduces the risk of overstress damage to components. Based on this, the controller 200 can output a corresponding control signal to each power conversion circuit 10, thereby adjusting the number of conduction times of the switch tubes in the N power conversion circuits 10 to balance the output power of the N power conversion circuits 10.

[0144] In other embodiments, when the control parameters are duty cycles D1 and D2, according to the frequency f s1 、f s2 The generated control signal is a pulse width modulation (PWM) control signal. When the power converter 100 is overloaded, the pulse width modulation can have a higher control efficiency and is suitable for high-power application scenarios. Based on this, the controller 200 can output a corresponding control signal to each power conversion circuit 10, thereby adjusting the conduction time of the switch tubes in the N power conversion circuits 10 to balance the output power of the N power conversion circuits 10.

[0145] In some other embodiments, the control signal may also be a combination of a PFM control signal and a PWM control signal. It should be understood that the type of the control signal may be selected according to actual conditions, and this application does not impose any special limitation on this.

[0146] In one embodiment, when N power conversion circuits 10 all use resonant conversion circuits, step S502 can also control the power conversion circuit 10 whose resonant frequency is lower than the preset frequency threshold to keep working at the allowed upper frequency limit, that is, the control parameter corresponding to the circuit 10 is the frequency and the frequency is kept at the allowed upper frequency limit; the frequency of other power conversion circuits 10 whose resonant frequency is higher than the preset frequency threshold is dynamically adjusted, that is, the control parameter corresponding to the other circuits 10 is the frequency and the frequency can be dynamically changed according to the actual situation, so that the control efficiency can be improved. The size of the preset frequency threshold can be set accordingly according to the actual situation, and is not specifically limited here.

[0147] It should be understood that in the aforementioned step S20, the reference parameter is greater than the M actual output parameters, which means that the reference parameter is different from at least the M actual output parameters. Therefore, the difference between the reference parameter and at least the M actual output parameters is not equal to 0, that is, at least M of the N differences are not equal to 0.

[0148] Since the difference is positively correlated with the initial adjustment parameter, among the N initial adjustment parameters obtained in step S30, at least M initial adjustment parameters are not equal to 0 or are larger values, so that at least M new target adjustment parameters can be generated in step S40 so that the corresponding control signals can play the adjustment function. In other words, the control signals generated by these new target adjustment parameters can effectively control at least M power conversion circuits 10 to adjust the target output parameters, so that the target output parameters of the N power conversion circuits 10 can be consistent and balanced.

[0149] For example, refer to Fig. 7A and Figure 7B In the embodiment, the actual output parameter and the target output parameter are both actual output currents. In step S20, the reference current I is obtained by taking the maximum value among the N actual output currents. Max Then, among the N actual output currents, the maximum actual output current is equal to the reference current I Max equal, N-1 actual output currents are less than the reference current I Max Therefore, among the N differences, the difference corresponding to the largest actual output current is equal to 0, and the rest, that is, N-1 differences, are not 0. Therefore, among the N initial adjustment currents, the initial adjustment current corresponding to the largest actual output current is 0 or a smaller value, and the initial adjustment currents corresponding to the other N-1 actual output currents are not 0 or a larger value. Furthermore, the target adjustment current corresponding to the largest actual output current is 0 or a smaller value, and the target adjustment currents corresponding to the other N-1 actual output currents are larger or not 0.

[0150] In this way, the current sharing control signal generated based on the target regulation current can control the N-1 power conversion circuits 10 with smaller actual output currents to increase the actual output currents, and the power conversion circuit 10 with the largest actual output current to reduce the actual output current or not need to adjust the actual output current. Therefore, the actual output currents of the N power conversion circuits 10 can be adjusted to balance in the end, and thus, the N power conversion circuits 10 can achieve power balance.

[0151] Figure 7C and Fig.7D , Fig. 8A and Figure 8B The same is true for the embodiments of the present invention, so it will not be repeated here.

[0152] In order to verify the balancing effect of the method of the embodiment of the present application, the embodiment of the present application also uses Figure 3 The circuit shown was simulated. Fig. 9 and Fig.10 , Fig. 9 Shows Figure 3 The circuit shown is a simulation waveform diagram when the control method of the embodiment of the present application is not adopted. Fig.10 Shows Figure 3 The circuit shown is a simulation waveform diagram when the control method of the embodiment of the present application is adopted. The environment of the two simulation experiments is the same.

[0153] For ease of description, Fig. 9 and Fig.10 It is shown that the input and output ends of the power conversion circuit 11 and the power conversion circuit 12 are connected in parallel, and when the power conversion circuit 11 and the power conversion circuit 12 are running in the forward direction, the frequency f of the power conversion circuit 11 s1 , actual output current I LV1 , three-phase primary current I pA1 ,I pB1 and I pC1 , the frequency f of the power conversion circuit 12 s2 , actual output current I LV2 , three-phase primary current I pA2 ,I pB2 and I pC2 The values ​​of the horizontal and vertical axes are only examples and do not constitute a limitation to the present application.

[0154] from Fig. 9 It can be seen that, when the control method of the embodiment of the present application is not adopted, the two power conversion circuits 10 operate at the same frequency, that is, f s1 and f s2 The two power conversion circuits 10 are basically the same, but due to the difference in the resonant frequencies of the two power conversion circuits 10, there will be a large difference in the three-phase primary currents generated by the two power conversion circuits 10, for example, I pA1,I pB1 and I pC1 The peak value is about 5A, I pA2 ,I pB2 and I pC2 The peak value reaches 10A. Based on this, the actual output current I of the two power conversion circuits 10 is LV1 and I LV2 The difference is large, for example, I LV1 and I LV2 The difference between them is more than 40A.

[0155] from Fig.10 It can be seen that, when the method of the embodiment of the present application is adopted, the two power conversion circuits 10 are controlled to operate at different frequencies, that is, f s1 and f s2 Different, where f s1 About 105kHz, f s2 The three-phase primary current I generated by the two power conversion circuits 10 is approximately 115kHz. pA1 ,I pB1 ,I pC1 ,I pA2 ,I pB2 ,I pC2 The peak values ​​of the two power conversion circuits 10 are the same or similar, for example, both are about 8A. The actual output current I LV1 and I LV2 The curves basically overlap, both reaching around 80A.

[0156] It can be seen that the control method of the embodiment of the present application can achieve Figure 3 The power conversion circuit 11 and the power conversion circuit 12 are shown to be current-balanced, and thus the output power of the power conversion circuit 11 and the power conversion circuit 12 can be balanced, and the actual output current of the power conversion circuit 11 and the power conversion circuit 12 can be adjusted to a larger current value, which is conducive to the application of the circuit in high-power scenarios. Obviously, the control method of the embodiment of the present application can play a role in balancing the control of multiple power conversion circuits 10.

[0157] In general, the control method of the power conversion circuit in the embodiment of the present application can perform balanced control on multiple connected power conversion circuits 10, so that the gain and impedance of the multiple connected power conversion circuits 10 are consistent, and the outputs of the multiple power conversion circuits 10 are balanced, avoiding current imbalance or voltage imbalance caused by parameter differences of different power conversion circuits 10, thereby leading to output power imbalance, thereby effectively avoiding the generation of ripples and preventing components and circuits from being overstressed, thereby improving the safety of components and circuits.

[0158] Moreover, regardless of the scenario in which the output ends of multiple power conversion circuits 10 are connected in parallel and run forward or reverse, or run unidirectionally or bidirectionally, or the scenario in which the output ends of multiple power conversion circuits 10 are connected in series and run forward, or regardless of which type of DC-DC conversion circuit is used by the multiple power conversion circuits 10, the control method of the power conversion circuit in the embodiment of the present application can be applied without the need to design different control methods for different scenarios and circuits. Therefore, the control method of the power conversion circuit in the present application has a wide range of adaptability, high compatibility, and low control complexity.

[0159] In addition, the method of the embodiment of the present application can perform current balancing control or voltage balancing control on the N power conversion circuits 10 according to the connection conditions of the N power conversion circuits 10, and can flexibly select the current loop or voltage loop to achieve regulation according to the actual situation. In other words, the N power conversion circuits 10 of the IPOP can be controlled for current balancing, which can be specifically as follows: Fig. 7A or Figure 7B As shown in the figure, current regulation and control is realized (i.e., current sharing control is realized through current loop regulation) or as Figure 7C or Fig.7D As shown in the figure, voltage regulation and current control are realized (i.e., current sharing control is realized by voltage loop regulation), and voltage sharing control can also be performed on the N power conversion circuits 10 of IPOS, which can be specifically as follows Fig. 8A As shown in the figure, current regulation and voltage control are realized (i.e. voltage equalization control is realized through current loop regulation) or as Figure 8B As shown, voltage regulation and control are achieved (ie, voltage equalization control is achieved through voltage loop regulation). It can be seen that the control method of the power conversion circuit of the present application has high control flexibility.

[0160] Please refer again Figure 1 , an embodiment of the present application also provides a power conversion device 300.

[0161] like Figure 1 As shown, the power conversion device 300 includes a power converter 100 and a controller 200. The power converter 100 and the controller 200 can be arranged in one piece or in a separate piece, which is not limited here. The power converter 100 includes N connected power conversion circuits 10, wherein the output ends of the N power conversion circuits 10 can be connected in parallel or in series.

[0162] It should be understood that the power converter 100 and the controller 200 may refer to the relevant description of the aforementioned embodiments, which will not be repeated here.

[0163] See also Fig.11 , an embodiment of the present application also provides an energy storage device 1000.

[0164] like Fig.11As shown, the energy storage device 1000 includes a power conversion device 300, an energy storage battery 400 and an energy storage converter 500 (Power Conversion System, PCS). The power conversion device 300, the energy storage battery 400 and the energy storage converter 500 can be separately arranged or at least partially integrated together, depending on actual needs.

[0165] The power conversion device 300 is the aforementioned Figure 1 The power conversion device 300 shown in FIG. 1 , wherein the low voltage side of the power converter 100 (i.e., the low voltage side of the N power conversion circuits 10) can be connected to the energy storage battery 400, and the high voltage side of the power converter 100 (i.e., the high voltage side of the N power conversion circuits 10) can be connected to the energy storage converter 500.

[0166] Therefore, when the power converter 100 is running in the forward direction, the energy storage inverter 500 can be used as a power source, the energy storage battery 400 can be used as a load, the energy storage inverter 500 can be used to power the power converter 100, and the power converter 100 can be used to transfer the energy of the energy storage inverter 500 to the energy storage battery 400 to charge the energy storage battery 400.

[0167] Alternatively, when the power conversion circuit 10 operates in reverse, the energy storage battery 400 can be used as a power source, the energy storage converter 500 can be used as a load, the energy storage battery 400 can be used to supply power to the power converter 100, and the power converter 100 can be used to transfer the energy of the energy storage battery 400 to the energy storage converter 500. In some embodiments, the energy storage converter 500 can also be used to connect to a power grid to draw power from the power grid or feed power to the power grid.

[0168] Moreover, during the operation of the power converter 100, the controller 200 can be used to execute the control method of the power conversion circuit to perform balanced control on the N power conversion circuits 10 in the power converter 100, thereby avoiding overstress failure of components and circuit damage caused by power imbalance, and the safety of components and the normal operation of the circuit are more guaranteed.

[0169] It should be understood that the control method of the power converter 100, the controller 200 and the power conversion circuit can refer to the relevant description in the aforementioned method embodiment, which will not be repeated here.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A control method for a power conversion circuit, characterized in that: N of the power conversion circuits are connected, N is a positive integer greater than or equal to 2, and the control method includes: Obtaining actual output parameters of N of the power conversion circuits; Obtaining a reference parameter according to actual output parameters of the N power conversion circuits; Obtaining N initial adjustment parameters of the power conversion circuit according to the difference between the actual output parameters of the N power conversion circuits and the reference parameters; wherein the difference is positively correlated with the initial adjustment parameters; Obtaining N target adjustment parameters of the power conversion circuit according to the N initial adjustment parameters, the N actual output parameters of the power conversion circuit and the set reference parameters; A control signal is generated according to the N target adjustment parameters, and the control signal is used to control the target output parameters of the N power conversion circuits so as to balance the output powers of the N power conversion circuits.

2. The control method according to claim 1, characterized in that: The actual output parameter includes at least one of a first actual output parameter and a second actual output parameter; When the output terminals of N power conversion circuits are connected in series, obtaining the reference parameter according to the actual output parameters of the N power conversion circuits includes: Obtaining a reference parameter according to the first actual output parameters of the N power conversion circuits, wherein the first actual output parameter is an actual output voltage; Alternatively, when the output ends of N power conversion circuits are connected in parallel, obtaining the reference parameter according to the actual output parameters of the N power conversion circuits includes: A reference parameter is obtained according to the second actual output parameters of the N power conversion circuits, wherein the second actual output parameter is the actual output current.

3. The control method according to claim 1 or 2, characterized in that: When the output terminals of N power conversion circuits are connected in series, the target output parameter is the actual output voltage; Accordingly, the process of generating a control signal according to the N target adjustment parameters, wherein the control signal is used to control the target output parameters of the N power conversion circuits so as to balance the output powers of the N power conversion circuits includes: Generate a voltage balancing control signal according to the N target adjustment parameters, wherein the voltage balancing control signal is used to control the actual output voltage of the N power conversion circuits so as to balance the output power of the N power conversion circuits; Alternatively, when the output ends of N power conversion circuits are connected in parallel, the target output parameter is the actual output current; Accordingly, the process of generating a control signal according to the N target adjustment parameters, wherein the control signal is used to control the target output parameters of the N power conversion circuits so as to balance the output powers of the N power conversion circuits includes: A current sharing control signal is generated according to the N target adjustment parameters, and the current sharing control signal is used to control the actual output current of the N power conversion circuits so as to balance the output power of the N power conversion circuits.

4. The control method according to claim 2, characterized in that: The step of obtaining N target adjustment parameters of the power conversion circuit according to the N initial adjustment parameters, the N actual output parameters of the power conversion circuit and the set reference parameters includes: Multiplying the N initial adjustment parameters by the preset proportional parameters respectively to obtain the N adjustment values ​​of the power conversion circuits; Subtracting the adjustment value of each power conversion circuit from the first actual output parameter of the corresponding power conversion circuit and then adding the resultant to the reference parameter to obtain a target adjustment parameter of the corresponding power conversion circuit; wherein the types of the target adjustment parameter and the reference parameter are the same as the type of the first actual output parameter; or, The adjustment value of each power conversion circuit is subtracted from the second actual output parameter of the corresponding power conversion circuit and then added to the reference parameter to obtain the target adjustment parameter of the corresponding power conversion circuit; wherein the types of the target adjustment parameter and the reference parameter are the same as the type of the second actual output parameter.

5. The control method according to any one of claims 1 to 4, characterized in that: The reference parameter is the target adjustment parameter in the historical working cycle.

6. The control method according to claim 1, characterized in that: The reference parameter is greater than M actual output parameters, where M is a positive integer less than N.

7. The control method according to claim 1, 2 or 6, characterized in that: The obtaining of the reference parameter according to the actual output parameters of the N power conversion circuits comprises: Taking the maximum value among the actual output parameters of N power conversion circuits to obtain the reference parameter; Alternatively, actual output parameters of N power conversion circuits are averaged to obtain the reference parameter.

8. The control method according to claim 1, characterized in that: The generating a control signal according to the N target adjustment parameters comprises: Performing deviation processing on the target adjustment parameters of the N power conversion circuits to obtain control parameters corresponding to the N power conversion circuits; the control parameters each include at least one of a duty cycle and a frequency; The control signal is generated according to the control parameters corresponding to the N power conversion circuits.

9. The control method according to claim 1, characterized in that: The power conversion circuit has a low voltage side and a high voltage side; the obtaining of N actual output parameters of the power conversion circuits includes: When the power conversion circuit is running in the forward direction, obtaining the actual output parameter on the low voltage side; Alternatively, when the power conversion circuit is running in reverse, obtaining the actual output parameter on the high voltage side; The forward operation refers to that the power conversion circuit transfers energy from the high voltage side to the low voltage side, and the reverse operation refers to that the power conversion circuit transfers energy from the low voltage side to the high voltage side.

10. The control method according to claim 1 or 9, characterized in that: The obtaining of actual output parameters of N power conversion circuits includes: Obtaining instantaneous values ​​of the actual output parameters of N power conversion circuits; averaging the instantaneous values ​​of the N power conversion circuits in at least one working cycle to obtain an average value of the N actual output parameters; The N average values ​​are used as actual output parameters of the N power conversion circuits.

11. A power conversion device, characterized in that: The power conversion device includes a controller and N power conversion circuits, the N power conversion circuits are connected, and N is a positive integer greater than or equal to 2; the controller is connected to the N power conversion circuits and is used to: Obtaining initial adjustment parameters of the N power conversion circuits according to differences between actual output parameters of the N power conversion circuits and reference parameters; wherein the difference is positively correlated with the initial adjustment parameter; Obtaining N target adjustment parameters of the power conversion circuit according to the N initial adjustment parameters, the N actual output parameters of the power conversion circuit and the set reference parameters; The target output parameters of the N power conversion circuits are controlled according to the N target adjustment parameters so as to balance the output powers of the N power conversion circuits.

12. The power conversion device according to claim 11, characterized in that: The actual output parameter includes at least one of a first actual output parameter and a second actual output parameter; When the output ends of N power conversion circuits are connected in series, the controller is used to: Obtaining initial adjustment parameters of the N power conversion circuits according to differences between the first actual output parameters of the N power conversion circuits and the reference parameters; Obtaining N target adjustment parameters of the power conversion circuit according to the N initial adjustment parameters, the N first actual output parameters of the power conversion circuit and the set reference parameters; or obtaining N target adjustment parameters of the power conversion circuit according to the initial adjustment parameters, the N second actual output parameters of the power conversion circuit and the set reference parameters; Wherein, the first actual output parameter is the actual output voltage, the second actual output parameter is the actual output current, the control signal is a voltage-sharing control signal, and the target output parameter is the actual output voltage; Alternatively, when the output ends of N power conversion circuits are connected in parallel, the controller is used to: Obtaining initial adjustment parameters of the N power conversion circuits according to differences between the second actual output parameters of the N power conversion circuits and the reference parameters; Obtaining N target adjustment parameters of the power conversion circuit according to the N initial adjustment parameters, the N first actual output parameters of the power conversion circuit and the set reference parameters; or obtaining N target adjustment parameters of the power conversion circuit according to the initial adjustment parameters, the N second actual output parameters of the power conversion circuit and the set reference parameters; Among them, the first actual output parameter is the actual output voltage, the second actual output parameter is the actual output current, the control signal is a current sharing control signal, and the target output parameter is the actual output current.

13. The power conversion device according to claim 11, characterized in that: The power conversion circuit includes at least one of a resonant conversion circuit, a BUCK circuit, a BOOST circuit, a BUCK-BOOST circuit, a dual active bridge conversion circuit, a forward conversion circuit, and a flyback conversion circuit.

14. The power conversion device according to claim 11 or 13, characterized in that: The power conversion circuit is a resonant conversion circuit, comprising: a primary bridge circuit, a resonant network, a transformer and a secondary bridge circuit, wherein the primary bridge circuit is connected to the primary side of the transformer through the resonant network, and the secondary bridge circuit is connected to the secondary side of the transformer; Among them, the primary bridge circuit includes at least two primary bridge arms, and the secondary bridge circuit includes at least two secondary bridge arms. The two ends of the at least two primary bridge arms form the high-voltage side of the power conversion circuit, and the two ends of the at least two secondary bridge arms form the low-voltage side of the power conversion circuit; each of the primary bridge arms and / or each of the secondary bridge arms includes a switching tube, and the resonant network includes a resonant inductor and a resonant capacitor.

15. An energy storage device, characterized in that: The energy storage device includes an energy storage battery and a power conversion device as described in any one of claims 11 to 14, wherein the energy storage battery is connected to the power conversion device and is used to supply power to the power conversion device or be charged by the power conversion device.

16. The energy storage device according to claim 15, characterized in that: The energy storage device further comprises an energy storage converter, wherein the energy storage converter is connected to the high voltage side of the power conversion device, and the energy storage battery is connected to the low voltage side of the power conversion device.

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