Single-stage isolation type charging circuit, control method, equipment and system thereof and medium

Abstract

The invention relates to the technical field of electric vehicles, particularly provides a single-stage isolation type charging circuit, a control method, equipment and system thereof and a medium, and aims to solve the problems of large size, high cost and low efficiency of a traditional two-stage type charging power supply module product. In order to achieve the purpose, the single-stage isolation type charging circuit comprises an alternating-current relay and a single-stage isolation type conversion circuit, and the alternating-current relay is connected with an alternating-current power grid so as to be used for controlling connection and disconnection of the voltage of the alternating-current power grid; the single-stage isolation type conversion circuit is electrically connected with the alternating-current relay; the single-stage isolation type conversion circuit is used for converting alternating-current voltage from an alternating-current power grid into direct-current voltage. According to the high-power charging power supply module, a circuit structure of a traditional high-power charging power supply module product is integrated into a first-stage circuit from a two-stage circuit, so that on the basis of realizing an alternating current and direct current conversion function, the use number of electronic devices is greatly reduced, the size of the power supply module product is reduced, and the cost of the power supply module product is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicles, and in particular to a single-stage isolated charging circuit and a control method, device, system and medium thereof. Background Art

[0002] With the increasing popularity of fast-charging and ultra-fast-charging models of electric vehicles, the demand for power module products that can realize high-power charging functions in electric vehicle charging piles and battery swap stations is increasing. The circuit architecture of traditional high-power charging power module products generally adopts a two-stage circuit topology, including the front-stage AC-to-DC circuit (ACDC) and the rear-stage DC-to-DC circuit (DCDC). The front-stage ACDC circuit usually adopts a three-phase Vienna rectifier circuit, a three-phase full-bridge rectifier circuit, etc., so as to convert the AC voltage from the power grid into a DC voltage and realize the power factor correction function (PFC, Power Factor Correction) on the grid side. The rear-stage DCDC circuit usually adopts an isolated DCDC circuit topology (such as a full-bridge LLC resonant circuit, a phase-shifted full-bridge circuit, etc.), so as to convert the DC voltage output by the ACDC circuit into a DC voltage that matches the battery voltage of the electric vehicle to realize the function of charging the electric vehicle; in addition, the rear-stage DCDC circuit realizes electrical isolation between the AC side and the DC side through a high-frequency transformer in the circuit to meet relevant requirements.

[0003] However, the traditional high-power charging power module adopts a two-stage circuit topology design, which not only increases the complexity of the circuit, but also requires the use of more electronic components, thereby increasing the manufacturing cost and limiting the miniaturization of the power module.

[0004] Accordingly, the art needs a new charging circuit solution to solve the above problems. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present application is proposed to solve or at least partially solve the technical problems of large volume, high cost and low efficiency existing in traditional two-stage charging power supply module products.

[0006] In a first aspect, a single-stage isolated charging circuit is provided, the circuit comprising an AC relay and a single-stage isolated conversion circuit, wherein the AC relay is connected to an AC power grid to control the connection and disconnection of the AC power grid voltage; the single-stage isolated conversion circuit is electrically connected to the AC relay; and the single-stage isolated conversion circuit is used to convert the AC voltage from the AC power grid into a DC voltage.

[0007] In a technical solution of the above-mentioned single-stage isolated charging circuit, the single-stage isolated conversion circuit includes at least one conversion module, the conversion module includes at least one conversion sub-circuit, the conversion sub-circuit is electrically connected to the AC power grid, and the conversion sub-circuit includes a full-bridge rectifier circuit, an energy storage device, a switching circuit, a resonant circuit, a rectifier and a filter.

[0008] In a technical solution of the above-mentioned single-stage isolated charging circuit, the full-bridge rectifier circuit is used to convert the AC voltage from the AC power grid into a DC voltage, the full-bridge rectifier circuit includes a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm each include two diodes, the two diodes of the first bridge arm and the second bridge arm are connected in series, the input end of the full-bridge rectifier circuit is connected to the AC power grid, and the output end of the full-bridge rectifier circuit is connected to the energy storage device.

[0009] In a technical solution of the above-mentioned single-stage isolated charging circuit, the energy storage device is used to store energy when the switching circuit is turned on, or to transfer the stored energy to the resonant circuit when the switching circuit is turned off. The energy storage device includes an AC inductor, and the input end of the energy storage device is connected to the output end of the full-bridge rectifier circuit, and the output end of the energy storage device is connected to the switching circuit and the resonant circuit.

[0010] In a technical solution of the above-mentioned single-stage isolated charging circuit, the switching circuit is used to achieve power factor correction by controlling the duty cycle of the switch tube driving signal, and the switching circuit includes a first switch tube and a second switch tube connected in series, the drain of the first switch tube is connected to the energy storage device and the resonant circuit, the source of the first switch tube is connected to the drain of the second switch tube and the resonant circuit, the source of the second switch tube is connected to the full-bridge rectifier circuit and the resonant circuit, and the first switch tube and the second switch tube include metal oxide semiconductor field effect transistors or insulated gate bipolar transistors.

[0011] In a technical solution of the above-mentioned single-stage isolated charging circuit, the resonant circuit is used to realize isolated energy transfer, and when the switching frequency of the switch tube is close to the resonance point of the resonant circuit, the switch circuit realizes soft switching; the resonant circuit includes a first resonant inductor, a second resonant inductor, a first resonant capacitor, a second resonant capacitor, a first transformer, and a second transformer, wherein the input end of the first resonant inductor is connected to the drain of the first switch tube and the output end of the energy storage device, and the output end of the first resonant inductor is connected to one end of the primary winding of the first transformer; the input end of the first resonant capacitor is connected to the other end of the primary winding of the first transformer, and the output end of the first resonant capacitor is connected to the source of the first switch tube, the second switch tube, and the output end of the first resonant capacitor. The drain of the first switch tube and the input end of the second resonant inductor; the input end of the second resonant inductor is connected to the source of the first switch tube, the drain of the second switch tube and the output end of the first resonant capacitor, and the output end of the second resonant inductor is connected to one end of the primary winding of the second transformer; the input end of the second resonant capacitor is connected to the other end of the primary winding of the second transformer, and the output end of the second resonant capacitor is connected to the source of the second switch tube and the full-bridge rectifier circuit; one end of the secondary windings of the first transformer and the second transformer are connected in parallel and then connected to the input end of the rectifier, and the output end of the rectifier is connected to the filter; the other end of the secondary windings of the first transformer and the second transformer are connected in parallel and then connected to the filter.

[0012] In a technical solution of the above-mentioned single-stage isolated charging circuit, the single-stage isolated charging circuit also includes a DC relay, and the DC relay includes at least one of a first DC relay, a second DC relay and a third DC relay; the first DC relay is connected to the negative pole of the output end of the conversion module, and / or the second DC relay is connected between the positive pole and the negative pole of the output end of the conversion module, and / or the third DC relay is connected to the positive pole of the output end of the conversion module; the DC relay is configured such that when the first DC relay and the third DC relay are closed and the second DC relay is disconnected, the single-stage isolated charging circuit enters a low-voltage charging mode; or, when the first DC relay and the third DC relay are disconnected and the second DC relay is closed, the single-stage isolated charging circuit enters a high-voltage charging mode; or, when the first DC relay and the third DC relay are disconnected and the second DC relay is closed, the single-stage isolated charging circuit enters a stop charging mode.

[0013] In a technical solution of the above-mentioned single-stage isolated charging circuit, the single-stage isolated charging circuit also includes a DC filter circuit and / or an anti-reverse circuit, the DC filter circuit is used to filter the high-frequency noise generated during the charging process, and the DC filter circuit includes a first common-mode inductor and a first safety capacitor, the input end of the first common-mode inductor is connected to the output end of the DC relay, the output end of the first common-mode inductor is connected to the first safety capacitor, and the output end of the first safety capacitor is electrically connected to the battery to be charged.

[0014] In a technical solution of the above-mentioned single-stage isolated charging circuit, the anti-reverse circuit is used to perform reverse cutoff when the positive and negative poles of the DC are reversed. The anti-reverse circuit includes at least one anti-reverse diode, the input end of the anti-reverse diode is connected to the first common-mode inductor and the first safety capacitor, and the output end of the anti-reverse diode is connected to the first safety capacitor and the battery to be charged.

[0015] In a technical solution of the above-mentioned single-stage isolated charging circuit, the AC power grid includes a single-phase AC power grid or a three-phase AC power grid. When the AC power grid is a single-phase AC power grid, at least one AC relay is connected to the input line of the single-phase AC power grid; or, when the AC power grid is a three-phase AC power grid, an AC relay is connected to each input line of the three-phase AC power grid.

[0016] In a technical solution of the above-mentioned single-stage isolated charging circuit, the single-stage isolated charging circuit also includes an AC filtering circuit and / or a lightning protection circuit, and the lightning protection circuit is used to absorb the voltage spike that surges to the AC port during lightning strikes to avoid damage to the single-stage isolated charging circuit caused by lightning surges; the lightning protection circuit includes a fuse, a varistor, and a gas discharge tube, the input end of the varistor is connected to the output end of the AC relay through the fuse, and the output end of the varistor is grounded through the gas discharge tube.

[0017] In a technical solution of the above-mentioned single-stage isolated charging circuit, the AC filter circuit is used to filter the high-frequency noise generated during the charging process, and the AC filter circuit includes a second common-mode inductor and a second safety capacitor; the input end of the second common-mode inductor is connected to the output end of one of the AC relays through the second safety capacitor and the lightning protection circuit, and the output end of the second common-mode inductor is connected to the single-stage isolated conversion circuit through the second safety capacitor.

[0018] In a second aspect, a control method for a single-stage isolated charging circuit is provided, the method being applied to the single-stage isolated charging circuit as described in any one of the above items, the method comprising: obtaining a DC output voltage and a DC output current output by the single-stage isolated charging circuit, an AC input voltage input by an AC power grid, and an AC current of an energy storage device in a single-stage isolated conversion circuit; determining an energy storage device current reference value based on the DC output voltage, the DC output current, and the AC input voltage; determining an AC current error based on the energy storage device current reference value and the AC current; determining duty cycle information based on the AC current error; and controlling a switching state of a switching circuit in the single-stage isolated conversion circuit based on the duty cycle information.

[0019] In a technical solution of the control method of the above-mentioned single-stage isolated charging circuit, the energy storage device current reference value is determined based on the DC output voltage, the DC output current, and the AC input voltage, including: determining a DC output voltage error based on the DC output voltage and the DC output voltage reference value; inputting the DC output voltage error into a DC voltage loop regulator to obtain an output result of the DC voltage loop regulator; determining a DC output current error based on the DC output current and the DC output current reference value; inputting the DC output current error into a DC current loop regulator to obtain an output result of the DC current loop regulator; adopting a dual-loop competition strategy for the output result of the DC voltage loop regulator and the output result of the DC current loop regulator, and taking the smaller value in the output result as the output result of the dual-loop competition; inputting the output result of the dual-loop competition and the AC voltage into a multiplier to determine the energy storage device current reference value.

[0020] In a technical solution of the control method of the above-mentioned single-stage isolated charging circuit, the duty cycle information is determined based on the AC current error, including: inputting the AC current error into an AC current loop regulator for calculation to determine the output result of the AC current loop controller; inputting the output result of the AC current loop controller into a PWM modulator to determine the duty cycle information.

[0021] In a technical solution of the control method of the above-mentioned single-stage isolated charging circuit, the method also includes: obtaining a control instruction of the DC relay, the control instruction including an opening instruction and / or a closing instruction for the DC relay; and controlling the charging mode of the single-stage isolated charging circuit based on the control instruction of the DC relay.

[0022] In a technical solution of the control method of the above-mentioned single-stage isolated charging circuit, the charging mode includes a low-voltage charging mode, a high-voltage charging mode or a stop charging mode, and the DC relay includes a first DC relay, a second DC relay and / or a third DC relay; the charging mode of the single-stage isolated charging circuit is controlled based on the control instruction of the DC relay, including: when the control instruction of the DC relay is to control the first DC relay and the third DC relay to be closed and the second DC relay to be disconnected, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in parallel, and the single-stage isolated charging circuit enters the low-voltage charging mode; when the control instruction of the DC relay is to control the first DC relay and the third DC relay to be disconnected and the second DC relay to be closed, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in series, and the single-stage isolated charging circuit enters the high-voltage charging mode; when the control instruction of the DC relay is to control the first DC relay, the third DC relay and the second DC relay to be disconnected, the single-stage isolated conversion circuit is disconnected from the battery to be charged, and the single-stage isolated charging circuit enters the stop charging mode.

[0023] In a third aspect, an electronic device is provided, comprising at least one processor and at least one memory, wherein the memory is suitable for storing a plurality of program codes, and the program codes are suitable for being loaded and run by the processor to execute the method described in any one of the technical solutions of the above-mentioned single-stage isolated charging circuit control method.

[0024] In a fourth aspect, a control system of a single-stage isolated charging circuit is provided, the system comprising the electronic device as described above, a DC voltage loop regulator, a DC current loop regulator, an AC current loop regulator, a multiplier, and a PWM modulator.

[0025] In a fifth aspect, a computer-readable storage medium is provided, in which a plurality of program codes are stored, wherein the program codes are suitable for being loaded and run by a processor to execute the method described in any one of the technical solutions of the above-mentioned single-stage isolated charging circuit control method.

[0026] Solution 1. A single-stage isolated charging circuit, characterized in that the circuit includes an AC relay and a single-stage isolated conversion circuit, wherein the AC relay is connected to an AC power grid to control the connection and disconnection of the AC power grid voltage; the single-stage isolated conversion circuit is electrically connected to the AC relay; and the single-stage isolated conversion circuit is used to convert the AC voltage from the AC power grid into a DC voltage.

[0027] Solution 2. The single-stage isolated charging circuit according to claim 1 is characterized in that the single-stage isolated conversion circuit includes at least one conversion module, the conversion module includes at least one conversion sub-circuit, the conversion sub-circuit is electrically connected to the AC power grid, and the conversion sub-circuit includes a full-bridge rectifier circuit, an energy storage device, a switching circuit, a resonant circuit, a rectifier and a filter.

[0028] Solution 3. The single-stage isolated charging circuit according to claim 2 is characterized in that the full-bridge rectifier circuit is used to convert the AC voltage from the AC power grid into a DC voltage, the full-bridge rectifier circuit includes a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm each include two diodes, the two diodes of the first bridge arm and the second bridge arm are connected in series, the input end of the full-bridge rectifier circuit is connected to the AC power grid, and the output end of the full-bridge rectifier circuit is connected to the energy storage device.

[0029] Solution 4. The single-stage isolated charging circuit according to claim 3 is characterized in that the energy storage device is used to store energy when the switch circuit is turned on, or to transfer the stored energy to the resonant circuit when the switch circuit is turned off, and the energy storage device includes an AC inductor, the input end of the energy storage device is connected to the output end of the full-bridge rectifier circuit, and the output end of the energy storage device is connected to the switch circuit and the resonant circuit.

[0030] Solution 5. The single-stage isolated charging circuit according to claim 2 is characterized in that the switching circuit is used to achieve power factor correction by controlling the duty cycle of the switch tube driving signal, and the switching circuit includes a first switch tube and a second switch tube connected in series, the drain of the first switch tube is connected to the energy storage device and the resonant circuit, the source of the first switch tube is connected to the drain of the second switch tube and the resonant circuit, the source of the second switch tube is connected to the full-bridge rectifier circuit and the resonant circuit, and the first switch tube and the second switch tube include metal oxide semiconductor field effect transistors or insulated gate bipolar transistors.

[0031] Solution 6. The single-stage isolated charging circuit according to claim 5 is characterized in that the resonant circuit is used to realize isolated energy transfer, and when the switching frequency of the switch tube is close to the resonance point of the resonant circuit, the switch circuit realizes soft switching; the resonant circuit includes a first resonant inductor, a second resonant inductor, a first resonant capacitor, a second resonant capacitor, a first transformer, and a second transformer, wherein:

[0032] The input end of the first resonant inductor is connected to the drain of the first switch tube and the output end of the energy storage device, and the output end of the first resonant inductor is connected to one end of the primary winding of the first transformer;

[0033] The input end of the first resonant capacitor is connected to the other end of the primary winding of the first transformer, and the output end of the first resonant capacitor is connected to the source of the first switch tube, the drain of the second switch tube and the input end of the second resonant inductor;

[0034] The input end of the second resonant inductor is connected to the source of the first switch tube, the drain of the second switch tube and the output end of the first resonant capacitor, and the output end of the second resonant inductor is connected to one end of the primary winding of the second transformer;

[0035] The input end of the second resonant capacitor is connected to the other end of the primary winding of the second transformer, and the output end of the second resonant capacitor is connected to the source of the second switch tube and the full-bridge rectifier circuit;

[0036] One end of the secondary windings of the first transformer and the second transformer is connected in parallel to the input end of the rectifier, and the output end of the rectifier is connected to the filter; the other end of the secondary windings of the first transformer and the second transformer is connected in parallel to the filter.

[0037] Solution 7. The single-stage isolated charging circuit according to claim 6 is characterized in that the single-stage isolated charging circuit further includes a DC relay, and the DC relay includes at least one of a first DC relay, a second DC relay and a third DC relay; the first DC relay is connected to the negative pole of the output end of the conversion module, and / or the second DC relay is connected between the positive pole and the negative pole of the output end of the conversion module, and / or the third DC relay is connected to the positive pole of the output end of the conversion module;

[0038] The DC relay is configured such that when the first DC relay and the third DC relay are closed and the second DC relay is open, the single-stage isolated charging circuit enters a low-voltage charging mode; or,

[0039] When the first DC relay and the third DC relay are disconnected and the second DC relay is closed, the single-stage isolated charging circuit enters a high-voltage charging mode; or,

[0040] When the first DC relay, the second DC relay, and the third DC relay are all disconnected, the single-stage isolated charging circuit enters a stop charging mode.

[0041] Solution 8. The single-stage isolated charging circuit according to claim 7 is characterized in that the single-stage isolated charging circuit also includes a DC filtering circuit and / or an anti-reverse circuit, the DC filtering circuit is used to filter the high-frequency noise generated during the charging process, and the DC filtering circuit includes a first common-mode inductor and a first safety capacitor, the input end of the first common-mode inductor is connected to the output end of the DC relay, the output end of the first common-mode inductor is connected to the first safety capacitor, and the output end of the first safety capacitor is electrically connected to the battery to be charged.

[0042] Solution 9. The single-stage isolated charging circuit according to claim 8 is characterized in that the anti-reverse circuit is used to perform reverse cutoff when the positive and negative poles of the DC are reversed, and the anti-reverse circuit includes at least one anti-reverse diode, the input end of the anti-reverse diode is connected to the first common-mode inductor and the first safety capacitor, and the output end of the anti-reverse diode is connected to the first safety capacitor and the battery to be charged.

[0043] Solution 10. The single-stage isolated charging circuit according to claim 1 is characterized in that the AC power grid includes a single-phase AC power grid or a three-phase AC power grid. When the AC power grid is a single-phase AC power grid, at least one AC relay is connected to the input line of the single-phase AC power grid; or, when the AC power grid is a three-phase AC power grid, an AC relay is connected to each input line of the three-phase AC power grid.

[0044] Solution 11. The single-stage isolated charging circuit according to claim 10 is characterized in that the single-stage isolated charging circuit also includes an AC filtering circuit and / or a lightning protection circuit, and the lightning protection circuit is used to absorb the voltage spike that surges to the AC port during lightning strikes to avoid damage to the single-stage isolated charging circuit caused by lightning surges; the lightning protection circuit includes a fuse, a varistor, and a gas discharge tube, the input end of the varistor is connected to the output end of the AC relay through the fuse, and the output end of the varistor is grounded through the gas discharge tube.

[0045] Solution 12. The single-stage isolated charging circuit according to claim 10 is characterized in that the AC filter circuit is used to filter the high-frequency noise generated during the charging process, and the AC filter circuit includes a second common-mode inductor and a second safety capacitor; the input end of the second common-mode inductor is connected to the output end of one of the AC relays through the second safety capacitor and the lightning protection circuit, and the output end of the second common-mode inductor is connected to the single-stage isolated conversion circuit through the second safety capacitor.

[0046] Solution 13. A control method for a single-stage isolated charging circuit, characterized in that the method is applied to the single-stage isolated charging circuit according to any one of claims 1 to 12, and the method comprises:

[0047] Obtaining a DC output voltage and a DC output current output by a single-stage isolated charging circuit, an AC input voltage input by an AC power grid, and an AC current of an energy storage device in a single-stage isolated conversion circuit;

[0048] Determine an energy storage device current reference value based on the DC output voltage, the DC output current, and the AC input voltage;

[0049] determining an AC current error based on the energy storage current reference value and the AC current;

[0050] Determining duty cycle information based on the AC current error;

[0051] Based on the duty cycle information, a switching state of a switch circuit in the single-stage isolated conversion circuit is controlled.

[0052] Solution 14. The control method of the single-stage isolated charging circuit according to claim 13, characterized in that the energy storage device current reference value is determined based on the DC output voltage, the DC output current, and the AC input voltage, comprising:

[0053] Determining a DC output voltage error based on the DC output voltage and a DC output voltage reference value;

[0054] Inputting the DC output voltage error into the DC voltage loop regulator to obtain the output result of the DC voltage loop regulator;

[0055] Determining a DC output current error based on the DC output current and a DC output current reference value;

[0056] Inputting the DC output current error into a DC current loop regulator to obtain an output result of the DC current loop regulator;

[0057] A dual-loop competition strategy is adopted for the output result of the DC voltage loop regulator and the output result of the DC current loop regulator, and the smaller value of the output results is used as the output result of the dual-loop competition;

[0058] The output result of the dual-loop competition and the AC voltage are input into a multiplier to determine a current reference value of the energy storage device.

[0059] Solution 15. The control method of the single-stage isolated charging circuit according to claim 14, characterized in that the determining of duty cycle information based on the AC current error comprises:

[0060] Inputting the AC current error into the AC current loop regulator for calculation to determine the output result of the AC current loop controller;

[0061] The output result of the AC current loop controller is input into the PWM modulator to determine the duty cycle information.

[0062] Solution 16. The control method of the single-stage isolated charging circuit according to claim 13, characterized in that the method further comprises:

[0063] Acquire a control instruction of the DC relay, wherein the control instruction includes an opening instruction and / or a closing instruction for the DC relay;

[0064] Based on the control instruction of the DC relay, the charging mode of the single-stage isolated charging circuit is controlled.

[0065] Solution 17. The control method of the single-stage isolated charging circuit according to claim 16, characterized in that the charging mode includes a low-voltage charging mode, a high-voltage charging mode or a stop charging mode, and the DC relay includes a first DC relay, a second DC relay and / or a third DC relay; the control instruction based on the DC relay to control the charging mode of the single-stage isolated charging circuit includes:

[0066] When the control instruction of the DC relay is to control the first DC relay and the third DC relay to be closed and the second DC relay to be disconnected, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in parallel, and the single-stage isolated charging circuit enters a low-voltage charging mode;

[0067] When the control instruction of the DC relay is to control the first DC relay and the third DC relay to be disconnected and the second DC relay to be closed, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in series, and the single-stage isolated charging circuit enters a high-voltage charging mode;

[0068] When the control instruction of the DC relay is to control the first DC relay, the third DC relay, and the second DC relay to be disconnected, the single-stage isolated conversion circuit is disconnected from the battery to be charged, and the single-stage isolated charging circuit enters a stop charging mode.

[0069] Solution 18. An electronic device comprising at least one processor and at least one memory, wherein the memory is suitable for storing multiple program codes, and wherein the program codes are suitable for being loaded and run by the processor to execute the control method of a single-stage isolated charging circuit as described in any one of claims 13 to 17.

[0070] Solution 19. A control system for a single-stage isolated charging circuit, characterized in that the system includes the electronic device as described in claim 18, a DC voltage loop regulator, a DC current loop regulator, an AC current loop regulator, a multiplier, and a PWM modulator.

[0071] Solution 20. A computer-readable storage medium storing a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute the control method of a single-stage isolated charging circuit according to any one of claims 13 to 17.

[0072] The above one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0073] The present application provides a single-stage isolated charging circuit, the circuit includes an AC relay and a single-stage isolated conversion circuit, wherein the AC relay is connected to an AC power grid to control the connection and disconnection of the AC power grid voltage; the single-stage isolated conversion circuit is electrically connected to the AC relay; the single-stage isolated conversion circuit is used to convert the AC voltage from the AC power grid into a DC voltage. The present application integrates the circuit architecture of a traditional high-power charging power supply module product from a two-stage circuit into a one-stage circuit, and on the basis of realizing the AC and DC conversion functions of the power supply module, greatly reduces the number of electronic devices used, thereby reducing the volume of the power supply module product and reducing the cost of the power supply module product. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The disclosure of the present application will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. Among them:

[0075] Figure 1 is a schematic diagram of the circuit structure of a charging power module according to the background technology of this application;

[0076] Figure 2 is a circuit structure schematic diagram of a single-stage isolated charging circuit according to an embodiment of the present application;

[0077] Figure 3 is a circuit structure schematic diagram of a single-stage isolated conversion circuit according to an embodiment of the present application;

[0078] Figure 4 is a schematic diagram of a circuit structure of a conversion module according to an embodiment of the present application;

[0079] Figure 5 is a schematic diagram of a circuit structure of a conversion sub-circuit according to an embodiment of the present application;

[0080] Figure 6 It is a schematic flow chart of main steps of a control method of a single-stage isolated charging circuit according to an embodiment of the present application;

[0081] Figure 7 is a schematic flow chart of steps of a control method for a single-stage isolated charging circuit according to another embodiment of the present application;

[0082] Figure 8 It is a schematic diagram of simulation waveforms of drain-source voltage, drain-source current waveform, and driving voltage of a switch circuit during charging operation according to an embodiment of the present application;

[0083] Fig. 9 It is a schematic diagram of simulation waveforms of the output DC voltage, output DC current, input AC current, and input AC voltage of a single-stage isolated charging circuit during charging operation according to an embodiment of the present application.

[0084] Fig.10 It is a schematic diagram of the main structure of an electronic device according to an embodiment of the present application.

[0085] Reference numerals:

[0086] 11: memory; 12: processor. DETAILED DESCRIPTION

[0087] Some embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0088] In the description of the present application, "module" and "processor" may include hardware, software or a combination of the two. A module may include hardware circuits, various suitable sensors, communication ports, memory, and may also include software parts, such as program code, or a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, hardware or a combination of the two. Computer-readable storage media include any suitable medium that can store program code, such as a disk, a hard disk, an optical disk, a flash memory, a read-only memory, a random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B or A and B. The term "at least one A or B" or "at least one of A and B" has a similar meaning to "A and / or B" and may include only A, only B or A and B. The singular terms "one" and "the" may also include plural forms.

[0089] With the increasing popularity of fast-charging and ultra-fast-charging electric vehicles, the demand for power module products that can achieve high-power charging functions in electric vehicle charging piles and battery swap stations is also increasing.

[0090] The circuit architecture of traditional high-power charging power module products is as follows: Figure 1 As shown, it generally adopts a two-stage circuit topology, including a front-stage AC-to-DC circuit (ACDC) and a rear-stage DC-to-DC circuit (DCDC). The front-stage ACDC circuit usually adopts a three-phase Vienna rectifier circuit, a three-phase full-bridge rectifier circuit, etc., so as to convert the AC voltage from the power grid into a DC voltage and realize the power factor correction function (PFC) on the power grid side. The rear-stage DCDC circuit usually adopts an isolated DCDC circuit topology (such as a full-bridge LLC resonant circuit, a phase-shifted full-bridge circuit, etc.), so as to convert the DC voltage output by the ACDC circuit into a DC voltage that matches the battery voltage of the electric vehicle, so as to realize the function of charging the electric vehicle; in addition, the rear-stage DCDC circuit realizes electrical isolation between the AC side and the DC side through a high-frequency transformer in the circuit to meet the relevant electrical isolation requirements.

[0091] It can be seen that the traditional high-power charging power module products adopt a two-stage circuit topology, which has a complex circuit and uses a large number of electronic devices, which is not conducive to reducing the size of the power module, reducing the cost of the power module, and improving the efficiency of the power module.

[0092] To this end, the present application provides a single-stage isolated charging circuit, the circuit comprising an AC relay and a single-stage isolated conversion circuit, wherein the AC relay is connected to the AC power grid to control the connection and disconnection of the AC power grid voltage; the single-stage isolated conversion circuit is electrically connected to the AC relay; the single-stage isolated conversion circuit is used to convert the AC voltage from the AC power grid into a DC voltage. The present application integrates the circuit architecture of the traditional high-power charging power module product from a two-stage circuit into a one-stage circuit, and on the basis of realizing the AC and DC conversion functions of the power module, greatly reduces the number of electronic devices used, thereby reducing the volume of the power module product and reducing the cost of the power module product.

[0093] See attached Figure 2 , Figure 2 FIG. 1 is a circuit structure diagram of a single-stage isolated charging circuit according to an embodiment of the present application. Figure 2As shown, the single-stage isolated charging circuit in the embodiment of the present application includes an AC relay and a single-stage isolated conversion circuit, wherein the AC relay is connected to the AC power grid to control the connection and disconnection of the AC power grid voltage; the single-stage isolated conversion circuit is electrically connected to the AC relay; the single-stage isolated conversion circuit is used to convert the AC voltage from the AC power grid into a DC voltage.

[0094] Specifically, the single-machine isolated charging circuit includes an AC relay and a single-stage isolated conversion circuit. The AC relay is connected to the AC power grid. The AC power grid includes a single-phase AC power grid or a three-phase AC power grid. In this embodiment, the AC power grid is a three-phase AC power grid as an example. Each phase of the three-phase AC power grid is connected to an AC relay, and the AC relay is used to control the connection and disconnection of the AC power grid voltage. The single-stage isolated conversion circuit is electrically connected to the AC relay and is configured to convert the AC voltage from the AC power grid into a DC voltage for charging the battery to be charged. For a single-phase AC power grid, the circuit structure and the number of components of the single-stage isolated conversion circuit can be adjusted according to the demand for charging power.

[0095] In one embodiment, the single-stage isolated conversion circuit includes at least one conversion module, the conversion module includes at least one conversion sub-circuit, the conversion sub-circuit is electrically connected to the AC power grid, and the conversion sub-circuit includes a full-bridge rectifier circuit, an energy storage device, a switching circuit, a resonant circuit, a rectifier and a filter.

[0096] See attached Figure 3 , Figure 3 FIG. 1 is a circuit structure diagram of a single-stage isolated conversion circuit according to an embodiment of the present application. Figure 3 As shown, in this embodiment, the single-stage isolated conversion circuit includes two conversion modules with the same structure, namely conversion module 1 and conversion module 2, and the two conversion modules evenly share the charging power of the power module.

[0097] See attached Figure 4 , Figure 4 FIG. 1 is a schematic diagram of a circuit structure of a conversion module according to an embodiment of the present application. Figure 4As shown, in this embodiment, each conversion module includes three conversion subcircuits, namely, conversion subcircuit 1, conversion subcircuit 2, and conversion subcircuit 3. The input end of each conversion subcircuit is electrically connected to the AC power grid. When the AC power grid is a three-phase AC power grid, the input end of each conversion subcircuit is respectively connected to the A phase and the B phase, the B phase and the C phase, and the A phase and the C phase of the three-phase AC power grid. The output ends of the three conversion subcircuits are connected in parallel and connected to the DC relay. The A phase of the three-phase AC power grid is respectively connected to the midpoint of the first bridge arm of the conversion subcircuit 1 and the midpoint of the second bridge arm of the conversion subcircuit 3; the B phase of the three-phase AC power grid is respectively connected to the midpoint of the second bridge arm of the conversion subcircuit 1 and the midpoint of the first bridge arm of the conversion subcircuit 2; the C phase of the three-phase AC power grid is respectively connected to the midpoint of the second bridge arm of the conversion subcircuit 2 and the midpoint of the first bridge arm of the conversion subcircuit 3.

[0098] When the AC power grid is a single-phase AC power grid, the single-stage isolated conversion circuit includes at least one conversion module, the conversion module includes at least one conversion subcircuit, and the input end of the conversion subcircuit is electrically connected to the live wire and the neutral wire of the single-phase AC power grid.

[0099] See attached Figure 5 , Figure 5 1 is a schematic diagram of the circuit structure of a conversion sub-circuit according to an embodiment of the present application. Figure 5 , the circuit structure of the conversion sub-circuit of the present application is described, and the conversion sub-circuit includes a full-bridge rectifier circuit, an energy storage device, a switching circuit, a resonant circuit, a rectifier and a filter.

[0100] In one embodiment, the full-bridge rectifier circuit is used to convert an AC voltage from an AC power grid into a DC voltage. The full-bridge rectifier circuit includes a first bridge arm and a second bridge arm. The first bridge arm and the second bridge arm each include two diodes. The two diodes of the first bridge arm and the second bridge arm are both connected in series. The input end of the full-bridge rectifier circuit is connected to the AC power grid, and the output end of the full-bridge rectifier circuit is connected to the energy storage device.

[0101] Specifically, the full-bridge rectifier circuit is composed of four diodes, namely D1, D2, D3 and D4. The full-bridge rectifier circuit includes a first bridge arm and a second bridge arm. Diodes D1 and D4 form the first bridge arm, and diode D1 is an upper arm switch, and diode D4 is a lower arm switch; diodes D2 and D3 form the second bridge arm, and diode D2 is an upper arm switch, and diode D3 is a lower arm switch; phase A of the three-phase AC power grid is connected to the midpoint of the first bridge arm of the conversion sub-circuit 1; phase B of the three-phase AC power grid is connected to the midpoint of the second bridge arm of the conversion sub-circuit 1; the input end of the diode D1 is electrically connected to phase A of the three-phase AC power grid, the input end of the diode D2 is electrically connected to phase B of the three-phase AC power grid, and the output ends of the diodes D1 and D2 are connected in parallel to the input end of the energy storage device; the input ends of the diodes D3 and D4 are connected in parallel to the switching circuit and the resonant circuit, the output end of the diode D3 is connected to phase B of the three-phase AC power grid, and the output end of the diode D4 is connected to phase A of the three-phase AC power grid.

[0102] The input voltage of the full-bridge rectifier circuit is the AC grid line voltage. The full-bridge rectifier circuit is used to convert the AC voltage input from the AC grid into a DC voltage to realize the ACDC voltage conversion function.

[0103] In one embodiment, the energy storage device is used to store energy when the switching circuit is turned on, or to transfer the stored energy to the resonant circuit when the switching circuit is turned off. The energy storage device includes an AC inductor, and the input end of the energy storage device is connected to the output end of the full-bridge rectifier circuit, and the output end of the energy storage device is connected to the switching circuit and the resonant circuit.

[0104] Specifically, the energy storage device refers to an AC inductor, the input end of the energy storage device is connected to the output ends of the diodes D1 and D2 of the full-bridge rectifier circuit, the output end of the energy storage device is connected to the switching circuit and the resonant circuit, and the energy storage device is configured such that when the switching circuit is turned on, the current of the energy storage device increases and stores energy; when the switching circuit is turned off, the current of the energy storage device decreases, and the energy stored in the energy storage device is transferred to the resonant circuit.

[0105] In one embodiment, the switching circuit is used to achieve power factor correction by controlling the duty cycle of the switching tube driving signal, and the switching circuit includes a first switching tube and a second switching tube connected in series, the drain of the first switching tube is connected to the energy storage device and the resonant circuit, the source of the first switching tube is connected to the drain of the second switching tube and the resonant circuit, the source of the second switching tube is connected to the full-bridge rectifier circuit and the resonant circuit, and the first switching tube and the second switching tube include metal oxide semiconductor field effect transistors or insulated gate bipolar transistors.

[0106] Specifically, the switch circuit includes a first switch tube Q1 and a second switch tube Q2, the first switch tube Q1 and the second switch tube Q2 are connected in series, the drain of the first switch tube Q1 is connected to the output end of the energy storage device and the resonant circuit, the source of the first switch tube Q1 is connected to the drain of the second switch tube Q2 and the resonant circuit, and the source of the second switch tube Q2 is connected to the resonant circuit and the input end of the diodes D3 and D4 of the full-bridge rectifier circuit. The duty cycle of the drive signal of the first switch tube Q1 and the second switch tube Q2 is controlled by PWM (Pulse Width Modulation) modulation, and a single conversion subcircuit can realize the functions of isolated ACDC voltage conversion and AC power grid side power factor correction, thereby meeting the functional requirements of the charging module. In addition, the first switch tube Q1 and the second switch tube Q2 are configured to be turned on and off at the same time. By controlling them to be turned on and off at the same time, the energy on the AC power grid side can be transferred to the rectifier through the resonant circuit, realizing the function of isolated energy transmission.

[0107] The first switch tube Q1 and the second switch tube Q2 may be metal oxide semiconductor field effect transistors (MOSFETs), or may be power semiconductor devices such as insulated gate bipolar transistors (IGBTs).

[0108] In one embodiment, the resonant circuit is used to realize isolated energy transfer, and when the switching frequency of the switch tube is close to the resonance point of the resonant circuit, the switch circuit realizes soft switching; the resonant circuit includes a first resonant inductor, a second resonant inductor, a first resonant capacitor, a second resonant capacitor, a first transformer, and a second transformer, wherein the input end of the first resonant inductor is connected to the drain of the first switch tube and the output end of the energy storage device, and the output end of the first resonant inductor is connected to one end of the primary winding of the first transformer; the input end of the first resonant capacitor is connected to the other end of the primary winding of the first transformer, and the output end of the first resonant capacitor is connected to the source of the first switch tube and the drain of the second switch tube. and the input end of the second resonant inductor; the input end of the second resonant inductor is connected to the source of the first switching tube, the drain of the second switching tube and the output end of the first resonant capacitor, and the output end of the second resonant inductor is connected to one end of the primary winding of the second transformer; the input end of the second resonant capacitor is connected to the other end of the primary winding of the second transformer, and the output end of the second resonant capacitor is connected to the source of the second switching tube and the full-bridge rectifier circuit; one end of the secondary windings of the first transformer and the second transformer are connected in parallel and then connected to the input end of the rectifier, and the output end of the rectifier is connected to the filter; the other end of the secondary windings of the first transformer and the second transformer are connected in parallel and then connected to the filter.

[0109] Specifically, the resonant circuit includes a first resonant inductor Lr1, a second resonant inductor Lr2, a first resonant capacitor C1, a second resonant capacitor C2, a first transformer T1, and a second transformer T2.

[0110] The input end of the first resonant inductor Lr1 is connected to the drain of the first switch tube Q1 and the output end of the energy storage device, and the output end of the first resonant inductor Lr1 is connected to the first end of the primary winding of the first transformer T1. The input end of the first resonant capacitor C1 is connected to the second end of the primary winding of the first transformer T1, and the output end of the first resonant capacitor C1 is connected to the source of the first switch tube Q1, the drain of the second switch tube Q2, and the input end of the second resonant inductor Lr2.

[0111] The input end of the second resonant inductor Lr2 is connected to the source of the first switch tube Q1, the drain of the second switch tube Q2 and the output end of the first resonant capacitor C1, and the output end of the second resonant inductor Lr2 is connected to the first end of the primary winding of the second transformer T2. The input end of the second resonant capacitor C2 is connected to the second end of the primary winding of the second transformer T2, and the output end is connected to the source of the second switch tube Q2 and the input ends of the diodes D3 and D4.

[0112] When the first switch tube Q1 and the second switch tube Q2 are turned off, the energy in the energy storage device L1 is transferred to the rectifier side after passing through the resonant circuit; when the first switch tube Q1 and the second switch tube Q2 are turned on, the current of the energy storage device L1 rises, the energy storage device L1 stores energy, and the current in the resonant circuit is reversed. By designing the switching frequency of the first switch tube Q1 and the second switch tube Q2 so that the switching frequency is close to the resonance point of the first resonant inductor Lr1, the second resonant inductor Lr2, the first resonant capacitor C1, and the second resonant capacitor C2, the first switch tube Q1 and the second switch tube Q2 can be operated in a soft switching state, that is, zero current switching and zero voltage switching, thereby greatly reducing the switching loss of the switch tube in the switching circuit, thereby optimizing the charging efficiency of the whole machine.

[0113] The conversion subcircuit also includes a rectifier D5 and a filter C3. The rectifier D5 refers to a rectifier diode connected to the secondary windings of the first transformer and the second transformer. One end of the secondary windings of the first transformer T1 and the second transformer T2 is connected in parallel and connected to the input end of the rectifier D5. The output end of the rectifier D5 is connected to one end of the filter C3. The other end of the secondary windings of the first transformer T1 and the second transformer T2 is connected in parallel and connected to the other end of the filter C3. The filter C3 refers to a DC filter capacitor. The filter C3 is configured to filter the DC voltage output by the conversion subcircuit. The single-stage isolated conversion circuit can realize the core functions of the charging power module, including power factor correction, electrical isolation and ACDC voltage conversion.

[0114] In one embodiment, the single-stage isolated charging circuit further includes a DC relay, which includes at least one of a first DC relay, a second DC relay and a third DC relay; the first DC relay is connected to the negative pole of the output end of the conversion module, and / or the second DC relay is connected between the positive pole and the negative pole of the output end of the conversion module, and / or the third DC relay is connected to the positive pole of the output end of the conversion module; the DC relay is configured such that when the first DC relay and the third DC relay are closed and the second DC relay is disconnected, the single-stage isolated charging circuit enters a low-voltage charging mode; or, when the first DC relay and the third DC relay are disconnected and the second DC relay is closed, the single-stage isolated charging circuit enters a high-voltage charging mode; or, when the first DC relay, the second DC relay and the third DC relay are all disconnected, the single-stage isolated charging circuit enters a stop charging mode.

[0115] like Figure 2 As shown, in this embodiment, the single-stage isolated charging circuit further includes a DC relay. When the AC power grid is a three-phase AC power grid, the DC relay includes a first DC relay K4, a second DC relay K5 and a third DC relay K6. The negative output terminals of each conversion sub-circuit in the first conversion module are connected in series to the input terminal of the first DC relay K4, and the output terminal of the first DC relay K4 is electrically connected to the negative output terminal of the second conversion module and the negative electrode of the battery to be charged.

[0116] The input end of the second DC relay K5 is connected to the positive output end of the second conversion module and the input end of the third DC relay K6, and the output end of the second DC relay K5 is connected in series with the negative electrode of each conversion sub-circuit in the first conversion module to achieve the effect of voltage series connection between the negative electrode of the first conversion module and the positive electrode of the second conversion module.

[0117] The input end of the third DC relay K6 is connected to the positive output end of the second conversion module and the input end of the second DC relay K5, and the output end of the third DC relay K6 is electrically connected to the positive output ends of each conversion sub-circuit in the first conversion module and the positive electrode of the battery to be charged.

[0118] By controlling the closing and / or disconnecting state of the DC relay, the switching between high and low voltage charging modes and the connection control between the charging module and the battery to be charged of the electric vehicle can be realized. When the first DC relay K4 and the third DC relay K6 are closed and the second DC relay K5 is disconnected, the DC outputs of the first conversion module and the second conversion module are connected in parallel, and the power module works in the low voltage charging mode (corresponding to the 400V battery voltage charging scenario); when the second DC relay K5 is closed and the first DC relay K4 and the third DC relay K6 are disconnected, the DC outputs of the first conversion module and the second conversion module are connected in series, and the power module works in the high voltage charging mode (corresponding to the 800V battery voltage charging scenario); when the first DC relay K4, the second DC relay K5 and the third DC relay K6 are all disconnected, the single-stage isolated conversion circuit is disconnected from the battery to be charged and stops charging the battery to be charged.

[0119] In one embodiment, the single-stage isolated charging circuit also includes a DC filter circuit and / or an anti-reverse circuit, wherein the DC filter circuit is used to filter the high-frequency noise generated during the charging process, and the DC filter circuit includes a first common-mode inductor and a first safety capacitor, wherein the input end of the first common-mode inductor is connected to the output end of the DC relay, the output end of the first common-mode inductor is connected to the first safety capacitor, and the output end of the first safety capacitor is electrically connected to the battery to be charged.

[0120] like Figure 2 As shown, in this embodiment, the single-stage isolated charging circuit also includes a DC filtering circuit and / or an anti-reverse circuit, wherein the DC filtering circuit is a DC EMI filtering circuit, including a first common-mode inductor and a first safety capacitor, and the DC filtering circuit is configured to filter out the high-frequency noise caused by the operation of devices such as the switching tube during the charging process to prevent it from being transmitted to the battery to be charged, so as to meet relevant electromagnetic compatibility (EMC) requirements.

[0121] One input end of the first common-mode inductor is connected to the positive output end of the DC relay, the other input end of the first common-mode inductor is connected to the negative output end of the DC relay, the output end of the first common-mode inductor is connected to the two ends of the first safety capacitor, one end of the first safety capacitor is connected to the anti-reverse circuit, and the other end of the first safety capacitor is connected to the negative electrode of the battery to be charged. The first safety capacitor includes an X capacitor and a Y capacitor. The number of the first common-mode inductor and the first safety capacitor can be set as needed.

[0122] In one embodiment, the anti-reverse circuit is used to perform reverse cutoff when the positive and negative poles of the DC are reversed. The anti-reverse circuit includes at least one anti-reverse diode, the input end of the anti-reverse diode is connected to the first common-mode inductor and the first safety capacitor, and the output end of the anti-reverse diode is connected to the first safety capacitor and the battery to be charged.

[0123] like Figure 2 As shown, in this embodiment, the anti-reverse circuit includes two anti-reverse diodes, the input ends of the two anti-reverse diodes are connected in parallel, and connected to the output end of the first common-mode inductor of the DC filter circuit and the first safety capacitor; the output ends of the two anti-reverse diodes are connected in parallel, and connected to the positive electrode of the battery to be charged. The anti-reverse circuit is used when the DC is reversely connected, and the anti-reverse diode is reversely cut off, which can prevent the energy of the battery from being reversed into the single-stage isolated charging circuit, causing damage to the device, so as to meet the relevant anti-reverse connection requirements.

[0124] In one embodiment, the AC power grid includes a single-phase AC power grid or a three-phase AC power grid. When the AC power grid is a single-phase AC power grid, at least one AC relay is connected to the input line of the single-phase AC power grid; or, when the AC power grid is a three-phase AC power grid, an AC relay is connected to each input line of the three-phase AC power grid.

[0125] like Figure 2 As shown, in this embodiment, when the AC power grid is a three-phase AC power grid, an AC relay is connected to each input line of the three-phase AC power grid, namely, AC relays K1, K2 and K3. When it is necessary to charge the battery to be charged, the AC relays K1, K2 and K3 are all closed, so that the voltage of the three-phase AC power grid is connected to the circuit of the rear stage of the AC relay; when charging stops or ends, the AC relays K1, K2 and K3 are all disconnected, so that the three-phase AC power grid is disconnected from the circuit of the rear stage of the AC relay. When the AC power grid is a single-phase AC power grid, at least one AC relay is set on the input line of the single-phase AC power grid to control the connection and disconnection of the voltage of the single-phase AC power grid.

[0126] In one embodiment, the single-stage isolated charging circuit also includes an AC filtering circuit and / or a lightning protection circuit, wherein the lightning protection circuit is used to absorb voltage spikes that surge to the AC port during a lightning strike to prevent damage to the single-stage isolated charging circuit caused by a lightning surge; the lightning protection circuit includes a fuse, a varistor, and a gas discharge tube, wherein the input end of the varistor is connected to the output end of the AC relay through the fuse, and the output end of the varistor is grounded through the gas discharge tube.

[0127] like Figure 2 As shown, in this embodiment, the single-stage isolated charging circuit also includes a lightning protection circuit, which is used to absorb the voltage spike that surges to the AC port during lightning strikes, thereby preventing the lightning surge from causing damage to the components in the ACDC circuit.

[0128] When the AC power grid is a three-phase AC power grid, the lightning protection circuit includes three fuses, three varistors (MOVs) and a gas discharge tube (GDT). The input end of each varistor is connected to one phase input line of the three-phase AC power grid through a fuse, and the output end of the varistor is connected in parallel and grounded through the gas discharge tube. When the AC power grid is a single-phase AC power grid, the number of fuses, varistors and gas discharge tubes in the lightning protection circuit can be set according to actual needs.

[0129] In one embodiment, the AC filter circuit is used to filter the high-frequency noise generated during the charging process, and the AC filter circuit includes a second common-mode inductor and a second safety capacitor; the input end of the second common-mode inductor is connected to the output end of one of the AC relays through the second safety capacitor and the lightning protection circuit, and the output end of the second common-mode inductor is connected to the single-stage isolated conversion circuit through the second safety capacitor.

[0130] Specifically, the single-stage isolated charging circuit also includes an AC filtering circuit, which is an AC EMI filtering circuit used to filter out the high-frequency noise caused by the operation of switching tubes and other devices during the charging process to prevent it from being transmitted to the grid side to meet relevant electromagnetic compatibility (EMC) requirements.

[0131] like Figure 2 As shown, in the case where the AC power grid is a three-phase AC power grid, the AC filtering circuit includes two second common-mode inductors, the two second common-mode inductors are connected in series, each second common-mode inductor includes three input ends and three output ends, the three input ends of the second common-mode inductor are respectively connected to the output end of an AC relay through a second safety capacitor and a lightning protection circuit, and the three output ends of the second common-mode inductor are respectively connected to the single-stage isolated conversion circuit through the second safety capacitor.

[0132] See attached Figure 6 , Figure 6 1 is a flow chart of the main steps of a control method of a single-stage isolated charging circuit according to an embodiment of the present application. In this embodiment, the control method of a single-stage isolated charging circuit is applied to the single-stage isolated charging circuit as described in any one of the above items, and mainly includes the following steps S101 to S105.

[0133] Step S101: obtaining a DC output voltage and a DC output current output by a single-stage isolated charging circuit, an AC input voltage input by an AC power grid, and an AC current of an energy storage device in a single-stage isolated conversion circuit.

[0134] Step S102: determining a current reference value of an energy storage device based on the DC output voltage, the DC output current, and the AC input voltage.

[0135] Step S103: determining an AC current error based on the energy storage current reference value and the AC current.

[0136] Step S104: Determine duty cycle information based on the AC current error.

[0137] Step S105: Based on the duty cycle information, controlling the switching state of the switch circuit in the single-stage isolated conversion circuit.

[0138] See attached Figure 7 , Figure 7 This is a schematic flow chart of the steps of a control method for a single-stage isolated charging circuit according to another embodiment of the present application. Figure 7 , the above steps S101 to S105 are further explained respectively.

[0139] For step S101, the DC output voltage and DC output current output by the single-stage isolated charging circuit, the AC input voltage of the AC grid, and the AC current of the energy storage device in the single-stage isolated conversion circuit are obtained.

[0140] like Figure 7 As shown, in this embodiment, the single-stage isolated charging circuit includes an output voltage / current outer loop and an AC inductor current inner loop. The outer loop adopts a control strategy of a DC output voltage loop and a DC output current loop competing with each other. In steady-state operation, only one loop is working, and the other loop is in a saturated output state.

[0141] Specifically, a voltage sampling circuit and a current sampling circuit are used to collect the DC output voltage and DC output current output by the single-stage isolated charging circuit, the AC input voltage of the AC power grid input, and the AC current of the energy storage device in the single-stage isolated conversion circuit.

[0142] With respect to step S102, the method of determining the energy storage device current reference value based on the DC output voltage, the DC output current, and the AC input voltage includes: determining a DC output voltage error based on the DC output voltage and the DC output voltage reference value; inputting the DC output voltage error into a DC voltage loop regulator to obtain an output result of the DC voltage loop regulator; determining a DC output current error based on the DC output current and the DC output current reference value; inputting the DC output current error into a DC current loop regulator to obtain an output result of the DC current loop regulator; adopting a dual-loop competition strategy for the output result of the DC voltage loop regulator and the output result of the DC current loop regulator, and taking the smaller value in the output result as the output result of the dual-loop competition; and inputting the output result of the dual-loop competition and the AC voltage into a multiplier to determine the energy storage device current reference value.

[0143] The DC voltage loop regulator and the DC current loop regulator are used to perform calculations respectively, and a dual-loop competition strategy is adopted for the output results of the DC voltage loop regulator and the output results of the DC current loop regulator. The calculation results are compared and the smaller value of the output results is used as the output of the dual-loop competition.

[0144] Specifically, the difference between the DC output voltage reference value and the DC output voltage is used to determine the DC output voltage error, and the DC output voltage error is input into the DC voltage loop regulator to obtain the output result of the DC voltage loop regulator. The difference between the DC output current reference value and the DC output current is used to determine the DC output current error, and the DC output current error is input into the DC current loop regulator to obtain the output result of the DC current loop regulator. The output result of the DC voltage loop regulator is compared with the output result of the DC current loop regulator, and the smaller value in the output result is used as the output result of the dual-loop competition. Then, the output result of the dual-loop competition is multiplied by the AC voltage input into the multiplier to obtain the energy storage current reference value. The energy storage current reference value has both the amplitude and phase information of the AC input voltage and the information of the DC output voltage and DC output current.

[0145] With respect to step S103 , an AC current error is determined based on the energy storage current reference value and the AC current.

[0146] Specifically, the AC current error is determined by using the difference between the AC current collected by the energy storage device current sampling circuit and the energy storage device current reference value.

[0147] For step S104, the duty cycle information is determined based on the AC current error, including: inputting the AC current error into the AC current loop regulator for calculation to determine the output result of the AC current loop controller; inputting the output result of the AC current loop controller into the PWM modulator to determine the duty cycle information.

[0148] Specifically, the AC current error is input into the AC current loop controller for calculation to obtain the output result of the AC current loop controller, and the output result of the AC current loop controller is input into the PWM modulator. The PWM modulator converts the output result of the AC current loop controller into the duty cycle information of the driving signals of the first switch tube Q1 and the second switch tube Q2 in the conversion sub-circuit.

[0149] In this embodiment, the DC voltage loop regulator, the DC current loop regulator, and the AC current loop regulator can use either a proportional integral (PI) controller or a proportional-integral-differential (PID) controller commonly used in the industry. The DC voltage loop regulator, the DC current loop regulator, and the PWM modulator are all calculated in a microcontroller chip (MCU, Micro Control Unit).

[0150] With respect to step S105 , based on the duty cycle information, the switching state of the switch circuit in the single-stage isolated conversion circuit is controlled.

[0151] Specifically, according to the duty cycle information, the switching states of the first switch tube Q1 and the second switch tube Q2 in the single-stage isolated conversion circuit are controlled to realize the charging of the battery to be charged in the electric vehicle and the power factor correction function.

[0152] In one embodiment, the method further includes: obtaining a control instruction of the DC relay, the control instruction including an opening instruction and / or a closing instruction for the DC relay; and controlling a charging mode of the single-stage isolated charging circuit based on the control instruction of the DC relay.

[0153] Specifically, according to the obtained opening instruction and / or closing instruction of the DC relay, the switching of the high-voltage and low-voltage charging modes of the single-stage isolated charging circuit is realized, and the connection control between the charging circuit and the battery to be charged of the electric vehicle is realized.

[0154] In one embodiment, the charging mode includes a low-voltage charging mode, a high-voltage charging mode or a stop charging mode, and the DC relay includes a first DC relay, a second DC relay and / or a third DC relay; the charging mode of the single-stage isolated charging circuit is controlled based on the control instruction of the DC relay, including: when the control instruction of the DC relay is to control the first DC relay and the third DC relay to be closed and the second DC relay to be disconnected, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in parallel, and the single-stage isolated charging circuit enters the low-voltage charging mode; when the control instruction of the DC relay is to control the first DC relay and the third DC relay to be disconnected and the second DC relay to be closed, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in series, and the single-stage isolated charging circuit enters the high-voltage charging mode; when the control instruction of the DC relay is to control the first DC relay, the third DC relay and the second DC relay to be disconnected, the single-stage isolated conversion circuit is disconnected from the battery to be charged, and the single-stage isolated charging circuit enters the stop charging mode.

[0155] Specifically, when the control instruction of the DC relay is to control the first DC relay K4 and the third DC relay K6 to be closed and the second DC relay K5 to be disconnected, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in parallel, and the single-stage isolated charging circuit enters a low-voltage charging mode to adapt to the 400V battery voltage charging scenario.

[0156] When the control instruction of the DC relay is to control the first DC relay K4 and the third DC relay K6 to be disconnected and the second DC relay K5 to be closed, the output ends of the conversion modules of the single-stage isolated conversion circuit are connected in series, and the single-stage isolated charging circuit enters the high-voltage charging mode to adapt to the 800V battery voltage charging scenario.

[0157] When the control instruction of the DC relay is to control the first DC relay K4, the third DC relay K6 and the second DC relay K5 to be disconnected, the single-stage isolated conversion circuit is disconnected from the battery to be charged, and the single-stage isolated charging circuit stops charging the battery to be charged.

[0158] See attached Figure 8 , Figure 8 1 is a schematic diagram of simulation waveforms of drain-source voltage (Vds), drain-source current waveform (Ids), and drive voltage (Vgs) of a switch tube of a switch circuit according to an embodiment of the present application during charging operation. Figure 8 As shown, at the moment when the first switch tube Q1 is turned on, the current (Ids) of the first switch tube Q1 resonates and rises from zero, so it is a zero current turn-on, and the turn-on loss is theoretically zero. At the moment when the first switch tube Q1 is turned off, the drain-source voltage (Vds) of the first switch tube Q1 resonates and rises from zero, so it is a zero voltage turn-off, and the turn-off loss is theoretically zero.

[0159] See attached Fig. 9 , Fig. 9 1 is a schematic diagram of simulated waveforms of the output DC voltage (Vo), output DC current (Io), input AC current (Iac), and input AC voltage (Uac) during charging operation of a single-stage isolated charging circuit according to an embodiment of the present application. Fig. 9 As shown, when executing the control method of a single-stage isolated charging circuit, the DC output voltage and current (Vo, Io) can be stabilized at the set values ​​(simulation setting 470V, 21A), and the AC current (Iac) is a sinusoidal current waveform with the same phase as the AC grid voltage (Uac). It can be seen that the present application can well realize the functions of ACDC voltage conversion and power factor correction.

[0160] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effect of the present application, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These adjusted schemes are equivalent to the technical schemes described in this application, and therefore will also fall within the scope of protection of this application.

[0161] It is understood by those skilled in the art that all or part of the processes in the method for implementing the above-mentioned embodiment of the present application can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc. that can carry the computer program code.

[0162] Another aspect of the present application also provides an electronic device. Fig.10 , Fig.10 In the example, it is shown that the memory 11 and the processor 12 are connected by bus communication. In an embodiment of an electronic device according to the present application, the intelligent device may include at least one processor; and a memory connected to the at least one processor; wherein a computer program is stored in the memory, and when the computer program is executed by at least one processor, the control method of the single-stage isolated charging circuit described in any of the above embodiments is implemented. The intelligent device described in the present application may include driving devices, smart cars, robots and other devices.

[0163] Another aspect of the present application provides a control system for a single-stage isolated charging circuit, wherein the system comprises the electronic device described above, a DC voltage loop regulator, a DC current loop regulator, an AC current loop regulator, a multiplier, and a PWM modulator.

[0164] Another aspect of the present application also provides a computer-readable storage medium. In an embodiment of a computer-readable storage medium according to the present application, the computer-readable storage medium can be configured to store a program for executing the control method of the single-stage isolated charging circuit of the above-mentioned method embodiment, and the program can be loaded and run by the processor to implement the control method of the above-mentioned single-stage isolated charging circuit. For ease of explanation, only the parts related to the embodiment of the present application are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present application. The computer-readable storage medium can be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present application is a non-temporary computer-readable storage medium.

[0165] So far, the technical solution of the present application has been described in conjunction with an embodiment shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A single-stage isolated charging circuit, characterized in that: The circuit includes an AC relay and a single-stage isolated conversion circuit, wherein the AC relay is connected to an AC power grid to control the connection and disconnection of the AC power grid voltage; the single-stage isolated conversion circuit is electrically connected to the AC relay; and the single-stage isolated conversion circuit is used to convert the AC voltage from the AC power grid into a DC voltage.

2. The single-stage isolated charging circuit according to claim 1, characterized in that: The single-stage isolated conversion circuit includes at least one conversion module, the conversion module includes at least one conversion sub-circuit, the conversion sub-circuit is electrically connected to the AC power grid, and the conversion sub-circuit includes a full-bridge rectifier circuit, an energy storage device, a switching circuit, a resonant circuit, a rectifier and a filter.

3. The single-stage isolated charging circuit according to claim 2, characterized in that: The full-bridge rectifier circuit is used to convert the AC voltage from the AC power grid into a DC voltage. The full-bridge rectifier circuit includes a first bridge arm and a second bridge arm. The first bridge arm and the second bridge arm each include two diodes. The two diodes of the first bridge arm and the second bridge arm are both connected in series. The input end of the full-bridge rectifier circuit is connected to the AC power grid, and the output end of the full-bridge rectifier circuit is connected to the energy storage device.

4. The single-stage isolated charging circuit according to claim 3, characterized in that: The energy storage device is used to store energy when the switching circuit is turned on, or to transfer the stored energy to the resonant circuit when the switching circuit is turned off. The energy storage device includes an AC inductor. The input end of the energy storage device is connected to the output end of the full-bridge rectifier circuit, and the output end of the energy storage device is connected to the switching circuit and the resonant circuit.

5. The single-stage isolated charging circuit according to claim 2, characterized in that: The switching circuit is used to achieve power factor correction by controlling the duty cycle of the switch tube driving signal. The switching circuit includes a first switch tube and a second switch tube connected in series, the drain of the first switch tube is connected to the energy storage device and the resonant circuit, the source of the first switch tube is connected to the drain of the second switch tube and the resonant circuit, the source of the second switch tube is connected to the full-bridge rectifier circuit and the resonant circuit, and the first switch tube and the second switch tube include metal oxide semiconductor field effect transistors or insulated gate bipolar transistors.

6. The single-stage isolated charging circuit according to claim 5, characterized in that: The resonant circuit is used to realize isolated energy transfer, and when the switching frequency of the switch tube is close to the resonance point of the resonant circuit, the switch circuit realizes soft switching; the resonant circuit includes a first resonant inductor, a second resonant inductor, a first resonant capacitor, a second resonant capacitor, a first transformer, and a second transformer, wherein: The input end of the first resonant inductor is connected to the drain of the first switch tube and the output end of the energy storage device, and the output end of the first resonant inductor is connected to one end of the primary winding of the first transformer; The input end of the first resonant capacitor is connected to the other end of the primary winding of the first transformer, and the output end of the first resonant capacitor is connected to the source of the first switch tube, the drain of the second switch tube and the input end of the second resonant inductor; The input end of the second resonant inductor is connected to the source of the first switch tube, the drain of the second switch tube and the output end of the first resonant capacitor, and the output end of the second resonant inductor is connected to one end of the primary winding of the second transformer; The input end of the second resonant capacitor is connected to the other end of the primary winding of the second transformer, and the output end of the second resonant capacitor is connected to the source of the second switch tube and the full-bridge rectifier circuit; One end of the secondary windings of the first transformer and the second transformer is connected in parallel to the input end of the rectifier, and the output end of the rectifier is connected to the filter; the other end of the secondary windings of the first transformer and the second transformer is connected in parallel to the filter.

7. The single-stage isolated charging circuit according to claim 6, characterized in that: The single-stage isolated charging circuit further includes a DC relay, which includes at least one of a first DC relay, a second DC relay and a third DC relay; the first DC relay is connected to the negative pole of the output end of the conversion module, and / or the second DC relay is connected between the positive pole and the negative pole of the output end of the conversion module, and / or the third DC relay is connected to the positive pole of the output end of the conversion module; The DC relay is configured such that when the first DC relay and the third DC relay are closed and the second DC relay is opened, the single-stage isolated charging circuit enters a low-voltage charging mode; or, When the first DC relay and the third DC relay are disconnected and the second DC relay is closed, the single-stage isolated charging circuit enters a high-voltage charging mode; or, When the first DC relay, the second DC relay, and the third DC relay are all disconnected, the single-stage isolated charging circuit enters a stop charging mode.

8. The single-stage isolated charging circuit according to claim 7, characterized in that: The single-stage isolated charging circuit also includes a DC filter circuit and / or an anti-reverse circuit. The DC filter circuit is used to filter the high-frequency noise generated during the charging process. The DC filter circuit includes a first common-mode inductor and a first safety capacitor. The input end of the first common-mode inductor is connected to the output end of the DC relay, the output end of the first common-mode inductor is connected to the first safety capacitor, and the output end of the first safety capacitor is electrically connected to the battery to be charged.

9. The single-stage isolated charging circuit according to claim 8, characterized in that: The anti-reverse circuit is used for reverse cutoff when the positive and negative poles of the direct current are reversely connected. The anti-reverse circuit includes at least one anti-reverse diode, the input end of the anti-reverse diode is connected to the first common-mode inductor and the first safety capacitor, and the output end of the anti-reverse diode is connected to the first safety capacitor and the battery to be charged.

10. The single-stage isolated charging circuit according to claim 1, characterized in that: The AC power grid includes a single-phase AC power grid or a three-phase AC power grid. When the AC power grid is a single-phase AC power grid, at least one AC relay is connected to the input line of the single-phase AC power grid; or, when the AC power grid is a three-phase AC power grid, an AC relay is connected to each input line of the three-phase AC power grid.

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