Control method and device of bidirectional power conversion circuit and charging system

Abstract

The application provides a control method and device of a bidirectional power conversion circuit and a charging system. The bidirectional power conversion circuit comprises two-stage resonant conversion circuits and two-stage Buck-Boost circuits connected one by one with the two-stage resonant conversion circuits. Each resonant conversion circuit comprises a primary full-bridge circuit and a secondary full-bridge circuit, and each Buck-Boost circuit comprises a full-bridge circuit. Each full-bridge circuit comprises at least two bridge arms, and each bridge arm comprises a first controllable switch and a second controllable switch connected in series. The first controllable switch and the second controllable switch each comprise a body diode. The control method of the bidirectional power conversion circuit comprises: selecting part / all of the freewheeling controllable switches as target controllable switches from the freewheeling controllable switches; turning off the driving signals of the target controllable switches and driving the controllable switches except the target controllable switches. The bidirectional power conversion circuit works in a non-synchronous rectification state, and energy backflow in the bidirectional power conversion circuit can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of charging circuit, and in particular to a control method and device of a bidirectional power conversion circuit and a charging system. BACKGROUND

[0002] At present, a synchronous rectification control method is used to replace the freewheeling diode in the circuit by using a switching tube, and then the two switching tubes in the circuit are controlled by using complementary driving signals, so that the circuit efficiency can be improved and the power loss in the circuit can be reduced. In the application scenario of a bidirectional charging pile, a double-layer circuit structure is usually used to provide a wide range of DC voltages.

[0003] However, when the double-layer circuit structure is used and the synchronous rectification control method is used, the bus capacitors of the layers of the circuit are commonly connected, and energy backflow is prone to occur, which can cause damage to the devices. SUMMARY

[0004] The embodiments of the present application provide a control method and device of a bidirectional power conversion circuit and a charging system to solve the problem of energy backflow that occurs when the bidirectional power conversion circuit is operated.

[0005] In a first aspect, the embodiments of the present application provide a control method of a bidirectional power conversion circuit. The bidirectional power conversion circuit includes a two-stage resonant conversion circuit, a bidirectional power converter connected to the two-stage resonant conversion circuit on the DC side, and a two-stage Buck-Boost circuit connected to the two-stage resonant conversion circuit one by one. Each stage of the resonant conversion circuit includes a primary side full-bridge circuit and a secondary side full-bridge circuit, and each stage of the Buck-Boost circuit includes a full-bridge circuit. Each full-bridge circuit includes at least two bridge arms, each bridge arm includes a first controllable switch and a second controllable switch connected in series, one end of the first controllable switch not connected to the second controllable switch is the high-voltage end of the bridge arm, and one end of the second controllable switch not connected to the first controllable switch is the low-voltage end of the bridge arm. The secondary side full-bridge circuit of each stage of the resonant conversion circuit is connected to the DC side of the bidirectional power converter, and the primary side full-bridge circuit of each stage of the resonant conversion circuit is connected to each full-bridge circuit. The connection point of the first controllable switch and the second controllable switch on each bridge arm is recorded as the target point of the bridge arm, the target points of all bridge arms in each stage of the Buck-Boost circuit are commonly connected to form the high-voltage DC end of the power conversion circuit, and the low-voltage ends of all bridge arms in each stage of the Buck-Boost circuit and the low-voltage ends of the bridge arms in all primary side full-bridge circuits are commonly connected to form the low-voltage DC end of the power conversion circuit. The AC end of the bidirectional power converter forms the AC end of the bidirectional power conversion circuit. The first controllable switch and the second controllable switch each include a body diode.

[0006] The control method of the bidirectional power conversion circuit includes the following steps:

[0007] If the working mode of the bidirectional power conversion circuit is the rectification mode, each second controllable switch is taken as a freewheeling controllable switch;

[0008] If the working mode of the bidirectional power conversion circuit is the inversion mode, each first controllable switch is taken as a freewheeling controllable switch;

[0009] selecting part / whole of the freewheeling controllable switches from each freewheeling controllable switch as target controllable switches;

[0010] turning off the drive signal of the target controllable switch, and driving the controllable switches other than the target controllable switch.

[0011] In a possible implementation, the selecting part / whole of the freewheeling controllable switches from each freewheeling controllable switch as target controllable switches comprises:

[0012] taking the freewheeling controllable switch in each primary-side full-bridge circuit as the target controllable switch,

[0013] and / or, taking the freewheeling controllable switch in each secondary-side full-bridge circuit as the target controllable switch.

[0014] In a possible implementation, the selecting part / whole of the freewheeling controllable switches from each freewheeling controllable switch as target controllable switches comprises:

[0015] taking the freewheeling controllable switch in each Buck-Boost circuit as the target controllable switch.

[0016] In a possible implementation, the selecting part / whole of the freewheeling controllable switches from each freewheeling controllable switch as target controllable switches comprises:

[0017] taking the freewheeling controllable switch in each Buck-Boost circuit as the target controllable switch, and taking all / part of the freewheeling controllable switches in each resonant conversion circuit as the target controllable switch;

[0018] wherein the taking all / part of the freewheeling controllable switches in each resonant conversion circuit as the target controllable switch comprises:

[0019] taking the freewheeling controllable switch in each primary-side full-bridge circuit as the target controllable switch, and / or, taking the freewheeling controllable switch in each secondary-side full-bridge circuit as the target controllable switch.

[0020] In a possible implementation, the driving each controllable switch other than the target controllable switch comprises:

[0021] interleaving driving two bridge arms in each Buck-Boost circuit.

[0022] In a possible implementation, the driving the controllable switches other than the target controllable switch comprises:

[0023] The Buck-Boost circuits at different levels are synchronously driven.

[0024] In a second aspect, an embodiment of the present application provides a control device of a bidirectional power conversion circuit, comprising:

[0025] The bidirectional power conversion circuit comprises two-stage resonant conversion circuits, a bidirectional power converter connected with the two-stage resonant conversion circuits, and two-stage Buck-Boost circuits connected with the two-stage resonant conversion circuits one by one; each resonant conversion circuit comprises a primary-side full-bridge circuit and a secondary-side full-bridge circuit, and each Buck-Boost circuit comprises a full-bridge circuit; each full-bridge circuit comprises at least two bridge arms, each bridge arm comprises a first controllable switch and a second controllable switch connected in series, one end of the first controllable switch not connected with the second controllable switch is a high-voltage end of the bridge arm, and one end of the second controllable switch not connected with the first controllable switch is a low-voltage end of the bridge arm; the secondary-side full-bridge circuit of each resonant conversion circuit is connected with the direct-current side of the bidirectional power converter, and the primary-side full-bridge circuit of each resonant conversion circuit is connected with each full-bridge circuit; the connection point of the first controllable switch and the second controllable switch on each bridge arm is recorded as a target point of the bridge arm, and the target points of all bridge arms in each Buck-Boost circuit are commonly connected to form a high-voltage direct-current end of the bidirectional power conversion circuit, and the low-voltage ends of all bridge arms in each Buck-Boost circuit and the low-voltage ends of the bridge arms in all primary-side full-bridge circuits are commonly connected to form a low-voltage direct-current end of the bidirectional power conversion circuit; the alternating-current end of the bidirectional power converter forms an alternating-current end of the bidirectional power conversion circuit; the first controllable switch and the second controllable switch each comprise a body diode;

[0026] The control device of the bidirectional power conversion circuit comprises:

[0027] The freewheeling selection module is configured to select each second controllable switch as a freewheeling controllable switch when the working mode of the bidirectional power conversion circuit is a rectification mode, and select each first controllable switch as a freewheeling controllable switch when the working mode of the bidirectional power conversion circuit is an inversion mode;

[0028] The target selection module is configured to select part / all of the freewheeling controllable switches as target controllable switches from the freewheeling controllable switches;

[0029] The driving module is configured to turn off a driving signal of the target controllable switch, and drive the controllable switches other than the target controllable switch.

[0030] In a third aspect, an embodiment of the present application provides a control device of a bidirectional power conversion circuit, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method of the first aspect or any possible implementation manner of the first aspect when executing the computer program.

[0031] In a fourth aspect, an embodiment of the present application provides a charging system, characterized in that the charging system comprises the bidirectional power conversion circuit applied in the first aspect and the control device of the bidirectional power conversion circuit provided in the third aspect.

[0032] The embodiment of the present application provides a control method and device of a bidirectional power conversion circuit and a charging system, the bidirectional power conversion circuit comprising two-stage resonant conversion circuits, a bidirectional power converter connected with the two-stage resonant conversion circuits on a direct current side, and two-stage Buck-Boost circuits connected with the two-stage resonant conversion circuits one by one; each resonant conversion circuit comprises a primary full-bridge circuit and a secondary full-bridge circuit, and each Buck-Boost circuit comprises a full-bridge circuit; each full-bridge circuit comprises at least two bridge arms, each bridge arm comprises a first controllable switch and a second controllable switch connected in series, one end of the first controllable switch not connected with the second controllable switch is a high-voltage end of the bridge arm, and one end of the second controllable switch not connected with the first controllable switch is a low-voltage end of the bridge arm; the secondary full-bridge circuit of each resonant conversion circuit is connected with the direct current side of the bidirectional power converter, and the primary full-bridge circuit of each resonant conversion circuit is connected with each full-bridge circuit; the connection point of the first controllable switch and the second controllable switch on each bridge arm is recorded as a target point of the bridge arm, the target points of all the bridge arms in each Buck-Boost circuit are commonly connected to form a high-voltage direct current end of the bidirectional power conversion circuit, and the low-voltage ends of all the bridge arms in each Buck-Boost circuit and the low-voltage ends of the bridge arms in all the primary full-bridge circuits are commonly connected to form a low-voltage direct current end of the bidirectional power conversion circuit; the alternating current end of the bidirectional power converter forms an alternating current end of the bidirectional power conversion circuit; the first controllable switch and the second controllable switch each comprise a body diode; the control method of the bidirectional power conversion circuit comprises: if the working mode of the bidirectional power conversion circuit is a rectification mode, each second controllable switch is used as a freewheeling controllable switch; if the working mode of the bidirectional power conversion circuit is an inversion mode, each first controllable switch is used as a freewheeling controllable switch; part / all of the freewheeling controllable switches are selected as target controllable switches from the freewheeling controllable switches; the driving signals of the target controllable switches are turned off, and the controllable switches other than the target controllable switches are driven. The embodiment of the present application turns off the freewheeling controllable switches in the full-bridge circuit, so that the freewheeling controllable switches are equivalent to diodes, the bidirectional power conversion circuit works in a non-synchronous rectification state, and energy backflow in the bidirectional power conversion circuit can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0034] Figure 1 is a circuit diagram of a Buck-Boost circuit provided by the embodiments of the present application;

[0035] Figure 2 is a circuit diagram of a resonant conversion circuit provided by the embodiments of the present application;

[0036] Figure 3 is a circuit diagram of a bidirectional power conversion circuit provided by the embodiments of the present application;

[0037] Figure 4 is an implementation flowchart of a control method of a bidirectional power conversion circuit provided by the embodiments of the present application;

[0038] Figure 5 is a structural schematic diagram of a control device of a bidirectional power conversion circuit provided by the embodiments of the present application;

[0039] Figure 6 is a structural schematic diagram of another control device of a bidirectional power conversion circuit provided by the embodiments of the present application. DETAILED DESCRIPTION

[0040] In the following description, specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, persons skilled in the art will understand that the present application can be practiced without these specific details. In other instances, well-known structures, devices, circuits and methods have not been described in detail in order to avoid obscuring the present application.

[0041] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described by specific embodiments in conjunction with the drawings.

[0042] Figure 1 is a circuit diagram of a Buck-Boost circuit provided by the embodiments of the present application. As shown in Figure 1 , the two-stage Buck-Boost circuit includes a first bridge arm, a second bridge arm, a first inductor L1, a second inductor L2, a first capacitor C1, a third bridge arm, a fourth bridge arm, a third inductor L4, a fourth inductor L5 and a second capacitor C4;

[0043] The first end of the Buck-Boost circuit comprises a positive first end and a negative first end; the second end of the Buck-Boost circuit comprises a positive bus end A and a negative bus end C; the first end of the resonant conversion circuit comprises a positive bus end D, a negative bus end E and a negative first end B;

[0044] The positive first end of the Buck-Boost circuit is connected with the positive pole of the energy storage device, and the negative first end of the Buck-Boost circuit is connected with the negative pole of the energy storage device; the positive bus end of the Buck-Boost circuit is connected with the positive bus end of the resonant conversion circuit, and the negative bus end of the Buck-Boost circuit is connected with the negative bus end of the resonant conversion circuit;

[0045] The positive first end of the Buck-Boost circuit is connected with the first end of the first inductor L1, the first end of the second inductor L2, the first end of the third inductor L4 and the first end of the fourth inductor L5 respectively; the second end of the first inductor L1 is connected with the target point of the first bridge arm, the second end of the second inductor L2 is connected with the target point of the second bridge arm, the second end of the third inductor L4 is connected with the target point of the third bridge arm, and the second end of the fourth inductor L5 is connected with the target point of the fourth bridge arm; the first end of the first bridge arm, the first end of the second bridge arm and the first end of the first capacitor C1 are connected with the positive bus end of the Buck-Boost circuit respectively; the first end of the third bridge arm, the first end of the fourth bridge arm and the first end of the second capacitor C4 are connected with the negative bus end of the Buck-Boost circuit respectively; the second end of the first bridge arm, the second end of the second bridge arm, the second end of the first capacitor C1, the second end of the third bridge arm, the second end of the fourth bridge arm and the second end of the second capacitor C4 are connected with the negative first end of the Buck-Boost circuit respectively.

[0046] The first bridge arm comprises controllable switches composed of the switching tube Q1 and the diode D15, and controllable switches composed of the switching tube Q1 and the diode D16, and the two controllable switches are connected in series, and the target point of the first bridge arm is the point connected by the two controllable switches. The second bridge arm comprises controllable switches composed of the switching tube Q3 and the diode D17, and controllable switches composed of the switching tube Q4 and the diode D18, and the two controllable switches are connected in series, and the target point of the second bridge arm is the point connected by the two controllable switches. The third bridge arm comprises controllable switches composed of the switching tube Q19 and the diode D19, and controllable switches composed of the switching tube Q23 and the diode D, and the two controllable switches are connected in series, and the target point of the third bridge arm is the point connected by the two controllable switches. The fourth bridge arm comprises controllable switches composed of the switching tube Q24 and the diode D21, and controllable switches composed of the switching tube Q14 and the diode D22, and the two controllable switches are connected in series, and the target point of the fourth bridge arm is the point connected by the two controllable switches.

[0047] The Buck-Boost circuit can realize the voltage reduction requirement during DC side charging and the voltage increase requirement during AC side charging.

[0048] Figure 2 A circuit diagram of the resonant conversion circuit is provided for the embodiment of the present application. Figure 2 As shown in the figure, the resonant conversion circuit comprises a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a ninth bridge arm, a tenth bridge arm, an eleventh bridge arm, a twelfth bridge arm, a first resonant cavity and a second resonant cavity.

[0049] The second end of the resonant conversion circuit comprises a positive first end F, a negative second end H and an intermediate bus end G; the first end of the bidirectional power converter comprises a positive first end I, a negative first end J and an intermediate bus end K.

[0050] The negative first end of the resonant conversion circuit is connected with the negative pole of the energy storage device, the positive first end of the resonant conversion circuit is connected with the positive first end of the bidirectional power converter, the negative second end of the resonant conversion circuit is connected with the negative first end of the bidirectional power converter, and the intermediate bus end of the resonant conversion circuit is connected with the intermediate bus end of the bidirectional power converter.

[0051] The first end of the fifth bridge arm and the first end of the sixth bridge arm are respectively connected with the positive bus end of the resonant conversion circuit, the first end of the seventh bridge arm and the first end of the eighth bridge arm are respectively connected with the negative bus end of the resonant conversion circuit, and the second end of the fifth bridge arm, the second end of the sixth bridge arm, the second end of the seventh bridge arm and the second end of the eighth bridge arm are respectively connected with the negative first end of the resonant conversion circuit.

[0052] The primary first end of the first resonant cavity is connected with the target point of the fifth bridge arm, and the primary second end of the first resonant cavity is connected with the target point of the sixth bridge arm; the secondary first end of the first resonant cavity is connected with the target point of the ninth bridge arm, and the secondary second end of the first resonant cavity is connected with the target point of the tenth bridge arm.

[0053] The primary first end of the second resonant cavity is connected with the target point of the seventh bridge arm, and the primary second end of the second resonant cavity is connected with the target point of the eighth bridge arm; the secondary first end of the second resonant cavity is connected with the target point of the eleventh bridge arm, and the secondary second end of the second resonant cavity is connected with the target point of the twelfth bridge arm.

[0054] The first end of the ninth bridge arm and the first end of the tenth bridge arm are respectively connected with the positive first end of the resonant conversion circuit; the first end of the eleventh bridge arm, the first end of the twelfth bridge arm, the second end of the ninth bridge arm and the second end of the tenth bridge arm are respectively connected with the intermediate bus end of the resonant conversion circuit; and the second end of the eleventh bridge arm and the second end of the twelfth bridge arm are respectively connected with the negative second end of the resonant conversion circuit.

[0055] The fifth bridge arm includes switch tubes Q5 and Q6, the sixth bridge arm includes switch tubes Q7 and Q8, the seventh bridge arm includes switch tubes Q13 and Q20, the eighth bridge arm includes switch tubes Q21 and Q22, the ninth bridge arm includes switch tubes Q9 and Q10, the tenth bridge arm includes switch tubes Q11 and Q12, the eleventh bridge arm includes switch tubes Q18 and Q17, and the twelfth bridge arm includes switch tubes Q16 and Q15. The connection relationship of the switch tubes in each bridge arm is shown in Figure 2 The target point of each bridge arm is the connection point of the two switch tubes in the bridge arm.

[0056] The first resonant cavity includes a first transformer, an inductor L3, and a capacitor C2. The first end of the primary side of the first transformer is the first end of the primary side of the first resonant cavity, the second end of the primary side of the first transformer is the second end of the primary side of the first resonant cavity, the first end of the secondary side of the first transformer is the first end of the secondary side of the first resonant cavity, and the second end of the secondary side of the first transformer is the second end of the secondary side of the first resonant cavity.

[0057] The second resonant cavity includes a second transformer, an inductor L6, and a capacitor C5. The first end of the primary side of the second transformer is the first end of the primary side of the second resonant cavity, the second end of the primary side of the second transformer is the second end of the primary side of the second resonant cavity, the first end of the secondary side of the second transformer is the first end of the secondary side of the second resonant cavity, and the second end of the secondary side of the second transformer is the second end of the secondary side of the second resonant cavity.

[0058] The resonant conversion circuit further includes a capacitor C3 and a capacitor C6. The first end of the capacitor C3 is connected to the first end of the positive electrode of the resonant conversion circuit, and the second end of the capacitor C3 and the first end of the capacitor C6 are respectively connected to the intermediate bus end of the resonant conversion circuit. The second end of the capacitor C6 is connected to the second end of the negative electrode of the resonant conversion circuit.

[0059] The positive and negative bus lines of the resonant conversion circuit output are connected into an intermediate bus line, which can provide a direct current voltage of for the bidirectional power converter.

[0060] In an embodiment, as shown in Figure 3 The bidirectional power converter includes a first transverse bridge arm, a second transverse bridge arm, a third transverse bridge arm, a first longitudinal bridge arm, a second longitudinal bridge arm, a third longitudinal bridge arm, a first filter unit, a second filter unit, and a third filter unit.

[0061] The second end of the bidirectional power converter includes an alternating current first end, an alternating current second end, and an alternating current third end.

[0062] The first end of the first transverse bridge arm, the first end of the second transverse bridge arm, and the first end of the third transverse bridge arm are connected to the middle bus of the bidirectional power converter respectively, the second end of the first transverse bridge arm is connected to the target point of the first longitudinal bridge arm, the second end of the second transverse bridge arm is connected to the target point of the second longitudinal bridge arm, the second end of the third transverse bridge arm is connected to the target point of the third longitudinal bridge arm, the first end of the first longitudinal bridge arm, the first end of the second longitudinal bridge arm, and the first end of the third longitudinal bridge arm are connected to the first positive end of the bidirectional power converter respectively, the second end of the first longitudinal bridge arm, the second end of the second longitudinal bridge arm, and the second end of the third longitudinal bridge arm are connected to the first negative end of the bidirectional power converter respectively, the target point of the first longitudinal bridge arm is further connected to the first end of the first filter unit, the second end of the first filter unit is connected to the first AC end, the target point of the second longitudinal bridge arm is further connected to the first end of the second filter unit, the second end of the second filter unit is connected to the second AC end, and the target point of the third longitudinal bridge arm is further connected to the first end of the third filter unit, the second end of the third filter unit is connected to the third AC end.

[0063] In the embodiment, the bidirectional power converter can be a T-type three-level inverter circuit. Figure 3 As shown in the figure, the first transverse bridge arm includes controllable switches composed of diode D2 and triode Q28, and controllable switches composed of diode D1 and triode Q27, and the two controllable switches are reversely connected between the first end and the second end of the first transverse bridge arm. The second transverse bridge arm includes controllable switches composed of diode D6 and triode Q, and controllable switches composed of diode D5 and triode Q29, and the two controllable switches are reversely connected between the first end and the second end of the second transverse bridge arm. The third transverse bridge arm includes controllable switches composed of diode D and triode Q34, and controllable switches composed of diode D9 and triode Q33, and the two controllable switches are reversely connected between the first end and the second end of the third transverse bridge arm. The first longitudinal bridge arm includes controllable switches composed of diode D2 and triode Q25, and controllable switches composed of diode D4 and triode Q26. The second longitudinal bridge arm includes controllable switches composed of diode D7 and triode Q32, and controllable switches composed of diode D8 and triode Q31. The third longitudinal bridge arm includes controllable switches composed of diode D11 and triode Q36, and controllable switches composed of diode D12 and triode Q36.

[0064] In the embodiment, the bidirectional power converter can be realized by the T-type three-level inverter circuit.

[0065] In one embodiment, the bidirectional power converter further includes a balance bridge arm and a zero line inductor.

[0066] The first end of the balance bridge arm is connected with the positive first end of the bidirectional power converter, and the second end of the balance bridge arm is connected with the negative first end of the bidirectional power converter.

[0067] The target point of the balance bridge arm is connected with the zero line through the zero line inductor.

[0068] In the embodiment, as shown in Figure 3 The balance bridge arm includes a controllable switch composed of a diode D14 and a triode Q37, and a controllable switch composed of a diode D13 and a triode Q38.

[0069] Specifically, by adding the balance bridge arm, the unbalanced load can be adjusted in the case that the off-grid load is greatly unbalanced.

[0070] In one embodiment, as shown in Figure 3 The first filter unit includes a fifth inductor, a sixth inductor, a third capacitor and a fourth capacitor; the second filter unit includes a seventh inductor, an eighth inductor, a fifth capacitor and a sixth capacitor; and the third filter unit includes a ninth inductor, a tenth inductor, a seventh capacitor and an eighth capacitor.

[0071] The first end of the fifth inductor is connected with the first end of the first filter unit, and the second end of the fifth inductor, the first end of the third capacitor and the first end of the fourth capacitor are respectively connected with the second end of the first filter unit; the second end of the third capacitor is connected with the first end of the sixth inductor.

[0072] The first end of the seventh inductor is connected with the first end of the second filter unit, and the second end of the seventh inductor, the first end of the fifth capacitor and the first end of the sixth capacitor are respectively connected with the second end of the second filter unit; the second end of the fifth capacitor is connected with the first end of the eighth inductor.

[0073] The first end of the ninth inductor is connected with the first end of the third filter unit, and the second end of the ninth inductor, the first end of the seventh capacitor and the first end of the eighth capacitor are respectively connected with the second end of the third filter unit; the second end of the seventh capacitor is connected with the first end of the tenth inductor.

[0074] The second end of the sixth inductor, the second end of the fourth capacitor, the second end of the eighth inductor, the second end of the sixth capacitor, the second end of the tenth inductor and the second end of the eighth capacitor are respectively connected with the middle bus of the bidirectional power converter.

[0075] Referring to Figure 4 , which shows an implementation flowchart of the control method of the bidirectional power conversion circuit provided by the embodiment of the present application, and is described in detail as follows:

[0076] In step 401, if the working mode of the bidirectional power conversion circuit is a rectification mode, each second controllable switch is used as a freewheeling controllable switch.

[0077] If the working mode of the bidirectional power converter is the inverting mode, the first controllable switch is used as a freewheeling controllable switch.

[0078] In the embodiment, if the working mode of the bidirectional power converter is the rectifying mode and the Buck-Boost circuit works in the Buck mode, the first controllable switch in the Buck-Boost circuit needs to be used as the main tube and the second controllable switch needs to be used as the freewheeling tube for synchronous rectification, and then the main tube and the freewheeling tube are synchronously controlled. This control method can reduce the conduction loss caused by the diode, but at the same time, energy backflow may occur, and the electric energy may flow back to other parts of the circuit, causing damage to the circuit devices. At this time, if the freewheeling tube is turned off, the freewheeling tube will be equivalent to a diode, and synchronous control is not needed to achieve freewheeling when needed, and the energy backflow to other parts of the circuit can be prevented. At the same time, the bidirectional power converter used in the application connects the two-stage resonant converter and the two-stage Buck-Boost circuit one by one, so that there is no path between the two-stage resonant converters, and the path of energy backflow is blocked, avoiding energy backflow in two aspects.

[0079] Similarly, if the working mode of the bidirectional power converter is the inverting mode and the Buck-Boost circuit works in the Boost mode, the first controllable switch in the Buck-Boost circuit is used as the freewheeling tube, and the first controllable switch is used as the freewheeling controllable switch.

[0080] Step 402, selecting part / whole of the freewheeling controllable switches as target controllable switches from the freewheeling controllable switches;

[0081] In the embodiment, the resonant converter includes two full-bridge circuits connected to the primary side and the secondary side of the resonant cavity, respectively. The two full-bridge circuits are similar in structure and function to the full-bridge circuit in the Buck-Boost circuit, so that the freewheeling controllable switches in the primary full-bridge circuit, the secondary full-bridge circuit, and any one of the full-bridge circuits are equivalent to diodes, and energy backflow can be avoided.

[0082] Step 403, turning off the driving signal of the target controllable switch and driving the controllable switches other than the target controllable switch.

[0083] In the embodiment, after the driving signal of the target controllable switch is turned off, the body diode in the target controllable switch can still be turned on, and the target controllable switch is equivalent to a diode. At this time, driving the controllable switches other than the target controllable switch can achieve non-synchronous rectification, avoiding energy backflow during rectification / inversion.

[0084] The embodiment of the present application selects part / whole of the freewheeling controllable switches in each full-bridge circuit as the target controllable switches, and makes the target controllable switches equivalent to diodes, so that the bidirectional power conversion circuit works in a non-synchronous rectification state, and energy backflow in the bidirectional power conversion circuit can be avoided.

[0085] In a possible implementation, selecting part / whole of the freewheeling controllable switches in each full-bridge circuit as the target controllable switches comprises:

[0086] selecting the freewheeling controllable switches in each primary-side full-bridge circuit as the target controllable switches,

[0087] and / or selecting the freewheeling controllable switches in each secondary-side full-bridge circuit as the target controllable switches.

[0088] In a possible implementation, selecting part / whole of the freewheeling controllable switches in each full-bridge circuit as the target controllable switches comprises:

[0089] selecting the freewheeling controllable switches in each primary-side full-bridge circuit as the target controllable switches,

[0090] and / or selecting the freewheeling controllable switches in each secondary-side full-bridge circuit as the target controllable switches.

[0091] In a possible implementation, selecting part / whole of the freewheeling controllable switches in each full-bridge circuit as the target controllable switches comprises:

[0092] selecting the freewheeling controllable switches in each primary-side full-bridge circuit as the target controllable switches,

[0093] and / or selecting the freewheeling controllable switches in each secondary-side full-bridge circuit as the target controllable switches.

[0094] In the embodiment, one, two or all of the freewheeling controllable switches in the three full-bridge circuits can be selected as the target controllable switches, and the target controllable switches are equivalent to diodes. The more the target controllable switches, the more the energy loss caused by the conduction of the diodes, and the better the effect of blocking energy backflow. Therefore, the freewheeling controllable switches in each full-bridge circuit can be distributed according to actual needs to obtain the optimal control effect.

[0095] In a possible implementation, driving each controllable switch except the target controllable switches comprises:

[0096] interleaving driving two bridge arms in each Buck-Boost circuit.

[0097] In the embodiment, the interleaved driving of the two bridge arms in each Buck-Boost circuit can reduce the total ripple after the superposition of inductance currents.

[0098] In a possible implementation, the driving of each controllable switch except the target controllable switch comprises:

[0099] The Buck-Boost circuits are synchronously driven.

[0100] In the embodiment, the Buck-Boost circuits need to be synchronously driven to achieve the DC voltage conversion function together.

[0101] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0102] The following is a device embodiment of the application. For details not described in detail, reference can be made to the corresponding method embodiments described above.

[0103] Figure 5 A structure diagram of a control device of a bidirectional power conversion circuit provided by an embodiment of the application is shown. For ease of illustration, only parts related to the embodiment of the application are shown, and details are described as follows.

[0104] As shown in Figure 5 The control device 5 of the bidirectional power conversion circuit comprises:

[0105] A freewheeling selection module 51 is configured to select each second controllable switch as a freewheeling controllable switch when the working mode of the bidirectional power conversion circuit is a rectification mode, and select each first controllable switch as a freewheeling controllable switch when the working mode of the bidirectional power conversion circuit is an inversion mode.

[0106] A target selection module 52 is configured to select part / all of the freewheeling controllable switches as target controllable switches from the freewheeling controllable switches.

[0107] A driving module 53 is configured to turn off the driving signal of the target controllable switch and drive the controllable switches except the target controllable switch.

[0108] The target selection module 52 is specifically configured to:

[0109] select the freewheeling controllable switch in each primary full-bridge circuit as the target controllable switch,

[0110] and / or select the freewheeling controllable switch in each secondary full-bridge circuit as the target controllable switch.

[0111] In a possible implementation, the target selection module 52 is specifically configured to:

[0112] The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch.

[0113] In a possible implementation, the target selection module 52 is specifically configured to:

[0114] The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch.

[0115] The all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch, including:

[0116] The freewheeling controllable switch in each primary full-bridge circuit is taken as the target controllable switch, and / or the freewheeling controllable switch in each secondary full-bridge circuit is taken as the target controllable switch.

[0117] In a possible implementation, the driving module 53 is specifically configured to:

[0118] The two bridge arms in each stage of the Buck-Boost circuit are driven in an interleaving manner.

[0119] In a possible implementation, the driving module 53 is specifically configured to:

[0120] The Buck-Boost circuits in each stage are driven in a synchronous manner.

[0121] By turning off the freewheeling controllable switch in the full-bridge circuit, the freewheeling controllable switch is equivalent to a diode, and the bidirectional power conversion circuit works in a non-synchronous rectification state, so that energy backflow in the bidirectional power conversion circuit can be avoided.

[0122] Figure 6 is a schematic diagram of the control device of the bidirectional power conversion circuit provided by the embodiment of the application. As shown in Figure 6 The control device 6 of the bidirectional power conversion circuit of this embodiment includes a processor 60, a memory 61, and a computer program 62 stored in the memory 61 and executable on the processor 60. The processor 60 implements the steps in each of the control method embodiments of the bidirectional power conversion circuit described above when executing the computer program 62, such as Figure 4 Steps 401 to 403 shown in. Alternatively, the processor 60 implements the functions of each module / unit in each of the device embodiments described above when executing the computer program 62, such as Figure 5 The functions of the modules / units 51 to 53 shown in.

[0123] For example, the computer program 62 can be divided into one or more modules / units, which are stored in the memory 61 and executed by the processor 60 to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program 62 in the control device 6 of the bidirectional power conversion circuit. For example, the computer program 62 can be divided into Figure 5 the modules / units 51 to 53.

[0124] The control device 6 of the bidirectional power conversion circuit can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The control device 6 of the bidirectional power conversion circuit can include, but is not limited to, a processor 60 and a memory 61. Those skilled in the art can understand that the control device 6 of the bidirectional power conversion circuit can include more or fewer components than those shown, or combine certain components, or different components, for example, the control device of the bidirectional power conversion circuit can also include an input / output device, a network access device, a bus, etc. Figure 6 The control device 6 of the bidirectional power conversion circuit is only an example and does not constitute a limitation on the control device 6 of the bidirectional power conversion circuit, and can include more or fewer components than those shown, or combine certain components, or different components, for example, the control device of the bidirectional power conversion circuit can also include an input / output device, a network access device, a bus, etc.

[0125] The processor 60 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic components, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0126] The memory 61 can be an internal storage unit of the control device 6 of the bidirectional power conversion circuit, such as a hard disk or a memory of the control device 6 of the bidirectional power conversion circuit. The memory 61 can also be an external storage device of the control device 6 of the bidirectional power conversion circuit, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, and the like equipped on the control device 6 of the bidirectional power conversion circuit. Further, the memory 61 can also include both the internal storage unit and the external storage device of the control device 6 of the bidirectional power conversion circuit. The memory 61 is used to store the computer program and other programs and data required by the control device of the bidirectional power conversion circuit. The memory 61 can also be used to temporarily store data that has been output or is to be output.

[0127] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or software. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the units and modules in the system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0128] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0129] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0130] In the embodiments of the present application, it should be understood that the control device and method of the disclosed bidirectional power conversion circuit can be implemented in other manners. For example, the above-described control device embodiment of the bidirectional power conversion circuit is merely illustrative. For example, the division of the modules or units is merely a logical function division. There can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or in other forms.

[0131] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units. That is, they can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0132] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware, or in the form of a software functional unit.

[0133] The integrated module / unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on this understanding, all or part of the processes in the above-described embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of the above-described various bidirectional power conversion circuit control method embodiments can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0134] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A control method of a bidirectional power conversion circuit, characterized by, The bidirectional power conversion circuit comprises two-stage resonant conversion circuits, a bidirectional power converter connected with the two-stage resonant conversion circuits, and two-stage Buck-Boost circuits connected with the two-stage resonant conversion circuits one by one; each resonant conversion circuit comprises a primary full-bridge circuit and a secondary full-bridge circuit, and each Buck-Boost circuit comprises a full-bridge circuit; each full-bridge circuit, the primary full-bridge circuit and the secondary full-bridge circuit comprise at least two bridge arms, each bridge arm comprises a first controllable switch and a second controllable switch connected in series, one end of the first controllable switch not connected with the second controllable switch is a high-voltage end of the bridge arm, one end of the second controllable switch not connected with the first controllable switch is a low-voltage end of the bridge arm, and the high-voltage ends of the Buck-Boost circuits are not directly connected; the secondary full-bridge circuit of each resonant conversion circuit is connected with the direct-current side of the bidirectional power converter, and the primary full-bridge circuit of each resonant conversion circuit is connected with the full-bridge circuit of the corresponding Buck-Boost circuit; the connection point of the first controllable switch and the second controllable switch on each bridge arm is recorded as a target point of the bridge arm, the target points of all the bridge arms in each Buck-Boost circuit are commonly connected to form a high-voltage direct-current end of the bidirectional power conversion circuit, and the low-voltage ends of all the bridge arms in each Buck-Boost circuit and the low-voltage ends of the bridge arms in all the primary full-bridge circuits are commonly connected to form a low-voltage direct-current end of the bidirectional power conversion circuit; the alternating-current end of the bidirectional power converter forms an alternating-current end of the bidirectional power conversion circuit; the first controllable switch and the second controllable switch each comprise a body diode; The control method of the bidirectional power conversion circuit comprises: if the working mode of the bidirectional power conversion circuit is a rectification mode, each second controllable switch is used as a freewheeling controllable switch; if the working mode of the bidirectional power conversion circuit is an inversion mode, each first controllable switch is used as a freewheeling controllable switch; selecting part / whole of the freewheeling controllable switches as target controllable switches from the freewheeling controllable switches; the selecting part / whole of the freewheeling controllable switches as target controllable switches from the freewheeling controllable switches comprises: selecting a freewheeling controllable switch in any one of the primary full-bridge circuit, the secondary full-bridge circuit and the full-bridge circuit of the Buck-Boost circuit as a target controllable switch; turning off the drive signal of the target controllable switch and driving the controllable switches other than the target controllable switch.

2. The control method of a bidirectional power conversion circuit according to claim 1, characterized by, the selecting a freewheeling controllable switch in any one of the primary full-bridge circuit, the secondary full-bridge circuit and the full-bridge circuit of the Buck-Boost circuit as a target controllable switch comprises: selecting a freewheeling controllable switch in each primary full-bridge circuit as a target controllable switch, and / or selecting a freewheeling controllable switch in each secondary full-bridge circuit as a target controllable switch.

3. The control method of a bidirectional power conversion circuit according to claim 1, characterized by, the selecting a freewheeling controllable switch in any one of the primary full-bridge circuit, the secondary full-bridge circuit and the full-bridge circuit of the Buck-Boost circuit as a target controllable switch comprises: The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch.

4. The control method of a bidirectional power conversion circuit according to claim 1, characterized by, The freewheeling controllable switch in any one of the primary side full bridge circuit, the secondary side full bridge circuit and the Buck-Boost circuit is taken as the target controllable switch. The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch. The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch. The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch.

5. The control method of a bidirectional power conversion circuit according to any one of claims 1 to 4, characterized by, The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch. The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch.

6. The control method of a bidirectional power conversion circuit according to any one of claims 1 to 4, characterized by, The freewheeling controllable switch in each stage of the Buck-Boost circuit is taken as the target controllable switch, and all / part of the freewheeling controllable switches in each stage of the resonant conversion circuit are taken as the target controllable switch. The two-way power conversion circuit comprises two stages of resonant conversion circuits, a two-way power converter connected with the two stages of resonant conversion circuits, and two stages of Buck-Boost circuits connected with the two stages of resonant conversion circuits one by one; each stage of resonant conversion circuit comprises a primary side full bridge circuit and a secondary side full bridge circuit, and each stage of Buck-Boost circuit comprises a full bridge circuit; each full bridge circuit, primary side full bridge circuit and secondary side full bridge circuit comprises at least two bridge arms, each bridge arm comprises a first controllable switch and a second controllable switch connected in series, one end of the first controllable switch not connected with the second controllable switch is the high voltage end of the bridge arm, one end of the second controllable switch not connected with the first controllable switch is the low voltage end of the bridge arm, and the high voltage ends of the Buck-Boost circuits are not directly connected; the secondary side full bridge circuit of each stage of resonant conversion circuit is connected with the direct current side of the two-way power converter, and the primary side full bridge circuit of each stage of resonant conversion circuit is connected with the full bridge circuit of the corresponding Buck-Boost circuit; the connection point of the first controllable switch and the second controllable switch on each bridge arm is recorded as the target point of the bridge arm, and the target points of all bridge arms in each stage of Buck-Boost circuit are commonly connected to form the high voltage direct current end of the two-way power conversion circuit, and the low voltage ends of all bridge arms in each stage of Buck-Boost circuit and the low voltage ends of bridge arms in all primary side full bridge circuits are commonly connected to form the low voltage direct current end of the two-way power conversion circuit; the alternating current end of the two-way power converter forms the alternating current end of the two-way power conversion circuit; the first controllable switch and the second controllable switch each contain a body diode; 7. A control device for a bidirectional power conversion circuit, characterized in that: The control device of the two-way power conversion circuit comprises: The freewheeling selection module is configured to take each second controllable switch as a freewheeling controllable switch when the working mode of the two-way power conversion circuit is a rectification mode, and take each first controllable switch as a freewheeling controllable switch when the working mode of the two-way power conversion circuit is an inversion mode. ​ The target selection module is configured to select part / whole of the freewheeling controllable switches as target controllable switches from the respective freewheeling controllable switches. The target selection module is specifically configured to: select the freewheeling controllable switches in any one of the full-bridge circuits in the primary full-bridge circuits, the secondary full-bridge circuits and the Buck-Boost circuits as the target controllable switches; The driving module is configured to turn off the driving signal of the target controllable switch and drive the controllable switches other than the target controllable switch.

8. The control device of a bidirectional power conversion circuit according to claim 7, characterized by, The target selection module is specifically configured to: select the freewheeling controllable switches in the respective primary full-bridge circuits as the target controllable switches, and / or select the freewheeling controllable switches in the respective secondary full-bridge circuits as the target controllable switches.

9. A control device for a bidirectional power conversion circuit, comprising a memory, a processor, and a computer program stored in the memory and operable on the processor, characterized in that, The processor, when executing the computer program, implements the steps of the control method of the bidirectional power conversion circuit according to any one of claims 1 to 6.

10. A charging system, characterized by The charging system comprises the bidirectional power conversion circuit according to the application and the control device of the bidirectional power conversion circuit according to claim 9.

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