Vehicle, on-board charger and control method thereof

Abstract

The present disclosure relates to a vehicle, an on-board charger and a control method thereof, which belongs to the field of vehicles and can reduce the demand for busbar capacitor capacity, improve the efficiency of the whole machine and reduce costs. A control method for an on-board charger comprises: when detecting grid access, obtaining a preset battery allowable minimum voltage of the power battery and a current battery voltage of the power battery; if the current battery voltage is lower than the preset battery allowable minimum voltage, increasing the voltage of the busbar capacitor by reducing the resonant gain of the isolated DC / DC circuit until it is detected that the voltage of the power battery reaches the preset battery allowable minimum voltage.

Description

Technical Field

[0001] The present disclosure relates to the field of vehicles, and in particular, to a vehicle, an on-board charger and a control method thereof. Background Art

[0002] The on-board charger is an on-board charging device used to charge the power battery of electric vehicles. In related technologies, the on-board charger usually adopts a two-stage topology, with the front stage being a power factor correction (PFC) circuit and the back stage being an isolated DC / DC circuit. A larger bus capacitor is selected between the two-stage circuits, generally an electrolytic capacitor, to balance the instantaneous power difference between the AC side and the DC side of the PFC circuit. However, electrolytic capacitors have a short working life and poor high temperature resistance, and are not suitable for the harsh working environment inside the vehicle. Summary of the invention

[0003] The purpose of the present disclosure is to provide a vehicle, an on-board charger and a control method thereof, which can reduce the demand for busbar capacitance, thereby eliminating the need to use electrolytic capacitors as busbar capacitors. In addition, the equivalent series resistance is reduced, the overall efficiency is improved, and the cost is reduced.

[0004] According to a first embodiment of the present disclosure, a control method for an on-board charger is provided, the on-board charger comprising a PFC circuit, a bus capacitor and an isolated DC / DC circuit, wherein a first output end of the PFC circuit is connected to a first input end of the isolated DC / DC circuit, a second output end of the PFC circuit is connected to a second input end of the isolated DC / DC circuit, the bus capacitor is connected between the first output end and the second output end of the PFC circuit, and the voltage of the bus capacitor is linked to the voltage of a power battery. The control method comprises: when grid access is detected, obtaining a preset minimum allowable battery voltage of the power battery and a current battery voltage of the power battery; if the current battery voltage is lower than the preset minimum allowable battery voltage, increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit until it is detected that the voltage of the power battery reaches the preset minimum allowable battery voltage.

[0005] Optionally, after the step of detecting that the voltage of the power battery reaches the preset minimum allowable battery voltage, the control method further includes: obtaining the current capacitor voltage of the bus capacitor and the preset minimum allowable capacitor voltage of the bus capacitor; if the current capacitor voltage is lower than the preset minimum allowable capacitor voltage, increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit until it is detected that the voltage of the bus capacitor reaches the preset minimum allowable capacitor voltage.

[0006] Optionally, after the step of obtaining the current capacitor voltage of the bus capacitor and the preset minimum allowable capacitor voltage of the bus capacitor, the control method further includes: if the current capacitor voltage is greater than or equal to the preset minimum allowable capacitor voltage, controlling the PFC circuit to output a constant current, and performing open-loop control of the isolated DC / DC circuit through a preset resonant frequency.

[0007] Optionally, the isolated DC / DC circuit includes a first conversion module, a transformer module and a second conversion module connected in sequence, the first conversion module is connected to the PFC circuit, and the second conversion module is connected to the power battery; then, the step of increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit includes: reducing the duty cycle of the first conversion module to reduce the resonant gain of the isolated DC / DC circuit to increase the voltage of the bus capacitor.

[0008] Optionally, the isolated DC / DC circuit includes a first conversion module, a transformer module and a second conversion module connected in sequence, the first conversion module is connected to the PFC circuit, and the second conversion module is connected to the power battery; then, the step of increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit includes: controlling the first conversion module to switch from a full-bridge control mode to a half-bridge control mode to reduce the resonant gain of the isolated DC / DC circuit to increase the voltage of the bus capacitor.

[0009] Optionally, the preset minimum allowable battery voltage is determined according to a maximum allowable input voltage of a power grid and a transformer turns ratio.

[0010] Optionally, the preset capacitor allowable minimum voltage is determined according to a maximum allowable input voltage of a power grid.

[0011] According to a second embodiment of the present disclosure, there is provided an on-board charger, the on-board charger comprising a PFC circuit, a bus capacitor and an isolated DC / DC circuit, wherein a first output end of the PFC circuit is connected to a first input end of the isolated DC / DC circuit, a second output end of the PFC circuit is connected to a second input end of the isolated DC / DC circuit, the bus capacitor is connected between the first output end and the second output end of the PFC circuit, the voltage of the bus capacitor is linked to the voltage of a power battery, and the on-board charger further comprises: a first acquisition module, for acquiring a preset minimum allowable battery voltage of the power battery and a current battery voltage of the power battery when grid access is detected; and a control module, for increasing the voltage of the bus capacitor by reducing the resonance gain of the isolated DC / DC circuit if the current battery voltage is lower than the preset minimum allowable battery voltage, until it is detected that the voltage of the power battery reaches the preset minimum allowable battery voltage.

[0012] Optionally, the on-board charger also includes a second acquisition module, which is used to obtain the current capacitor voltage of the bus capacitor and the preset minimum capacitor allowable voltage of the bus capacitor after the voltage of the power battery reaches the preset battery allowable minimum voltage; the control module is also used to increase the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit if the current capacitor voltage is lower than the preset minimum capacitor allowable voltage, until it is detected that the voltage of the bus capacitor reaches the preset minimum capacitor allowable voltage.

[0013] According to a third embodiment of the present disclosure, a vehicle is provided, comprising the on-vehicle charger according to the second embodiment of the present disclosure.

[0014] In the present application, since the voltage of the bus capacitor is linked to the voltage of the power battery, when the voltage of the power battery is low, the first voltage of the linked bus capacitor is also low. However, after being connected to the power grid, the second voltage output to the bus capacitor through the PFC circuit may be relatively high. Therefore, there is a large voltage difference between the first voltage and the second voltage. The large voltage difference will lead to uncontrolled rectification and even abnormally large current, thereby damaging related electronic devices in the on-board charger.

[0015] In order to avoid the occurrence of uncontrolled rectification, when the present application detects grid access, when the current battery voltage is lower than the preset minimum allowable battery voltage, the voltage of the bus capacitor is increased by reducing the resonant gain of the isolated DC / DC circuit until the voltage of the power battery is detected to reach the preset minimum allowable battery voltage, so that the voltage of the bus capacitor can be automatically increased, thereby causing the difference between the first voltage and the second voltage to be smaller, thereby effectively avoiding the occurrence of uncontrolled rectification and the generation of abnormally large current.

[0016] In addition, since the voltage of the bus capacitor is linked to the voltage of the power battery, the voltage of the bus capacitor will not fluctuate greatly, so there is no need to set an electrolytic capacitor with a withstand voltage value (that is, the maximum rated voltage of the capacitor does not need to be set very high), and thus the application can use a small-capacity film capacitor as the bus capacitor, thereby improving the high-temperature resistance of the bus capacitor. Since the capacitance of the bus capacitor is reduced, the equivalent series resistance can be reduced, the overall efficiency can be improved, and the cost can be reduced.

[0017] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0019] Figure 1 A topological diagram of a vehicle charger according to an embodiment of the present disclosure is shown.

[0020] Figure 2 It is a flow chart of a control method of a vehicle charger according to an embodiment of the present disclosure.

[0021] Figure 3 This is another flow chart of a method for controlling a vehicle charger according to an embodiment of the present disclosure.

[0022] Figure 4 is another flow chart of a method for controlling a vehicle charger according to an embodiment of the present disclosure.

[0023] Figure 5 1 is a circuit diagram of a vehicle charger according to an embodiment of the present disclosure.

[0024] Figure 6 It is a schematic block diagram of a vehicle charger according to an embodiment of the present disclosure.

[0025] Figure 7 A schematic diagram of a duty cycle adjustment strategy of an on-board charger according to an embodiment of the present disclosure is shown.

[0026] Figure 8 is a schematic logic diagram of a controlled PFC circuit according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0028] Figure 1 FIG. 1 shows a topological diagram of a vehicle charger according to an embodiment of the present disclosure. Figure 1 As shown, the on-board charger 1 includes a PFC circuit 10, a bus capacitor C1 and an isolated DC / DC circuit 20, a first output end of the PFC circuit 10 is connected to a first input end of the isolated DC / DC circuit 20, a second output end of the PFC circuit 10 is connected to a second input end of the isolated DC / DC circuit 20, the bus capacitor C1 is connected between the first output end and the second output end of the PFC circuit 10, and the voltage of the bus capacitor C1 is linked to the voltage of the power battery 3.

[0029] Figure 2 FIG. 1 is a flow chart of a control method of a vehicle charger according to an embodiment of the present disclosure. Figure 2 As shown, the control method of the on-board charger includes the following steps S21 to S22.

[0030] In step S21, when grid access is detected, a preset minimum allowable battery voltage of the power battery and a current battery voltage of the power battery are obtained.

[0031] In some embodiments, the current battery voltage of the power battery may be obtained from a sensor that detects the voltage of the power battery, or may be obtained from a battery management system.

[0032] In some embodiments, the preset minimum allowable battery voltage can be obtained from a memory storing the preset minimum allowable battery voltage of the power battery, or the preset minimum allowable battery voltage can be obtained from a cloud server or the like.

[0033] The preset battery allowable minimum voltage of the power battery can be determined according to the maximum allowable input voltage of the power grid and the transformer turns ratio. For example, the preset battery allowable minimum voltage can be equal to the maximum allowable input voltage of the power grid divided by the transformer turns ratio.

[0034] In step S22, if the current battery voltage is lower than the preset minimum allowable battery voltage, the voltage of the bus capacitor is increased by reducing the resonant gain of the isolated DC / DC circuit until it is detected that the voltage of the power battery reaches the preset minimum allowable battery voltage.

[0035] Since the voltage of the bus capacitor is linked to the voltage of the power battery, reducing the resonant gain of the isolated DC / DC circuit will increase the voltage of the bus capacitor.

[0036] In addition, the bus capacitor uses film capacitors, etc.

[0037] In this embodiment, since the voltage of the bus capacitor is linked to the voltage of the power battery, when the voltage of the power battery is low, the first voltage of the linked bus capacitor is also low. However, after connecting to the power grid, the second voltage output to the bus capacitor through the PFC circuit may be relatively high. Therefore, there is a large voltage difference between the first voltage and the second voltage. The large voltage difference will lead to uncontrolled rectification and even abnormally large current, thereby damaging related electronic devices in the on-board charger.

[0038] In order to avoid the occurrence of uncontrolled rectification, when the present application detects grid access, when the current battery voltage is lower than the preset minimum allowable battery voltage, the voltage of the bus capacitor is increased by reducing the resonant gain of the isolated DC / DC circuit until the voltage of the power battery is detected to reach the preset minimum allowable battery voltage, so that the voltage of the bus capacitor can be automatically increased, thereby causing the difference between the first voltage and the second voltage to be smaller, thereby effectively avoiding the occurrence of uncontrolled rectification and the generation of abnormally large current.

[0039] In addition, since the voltage of the bus capacitor is linked to the voltage of the power battery, the voltage of the bus capacitor will not fluctuate greatly, so there is no need to set an electrolytic capacitor with a withstand voltage value (that is, the maximum rated voltage of the capacitor does not need to be set very high), and thus the application can use a small-capacity film capacitor as the bus capacitor, thereby improving the high-temperature resistance of the bus capacitor. Since the capacitance of the bus capacitor is reduced, the equivalent series resistance can be reduced, the overall efficiency can be improved, and the cost can be reduced.

[0040] Figure 3 FIG. 1 is another flow chart of a method for controlling a vehicle charger according to an embodiment of the present disclosure. Figure 3 As shown, the control method further includes step S23 and step S24 after step S22.

[0041] In step S23, the current capacitor voltage of the bus capacitor and the preset minimum capacitor voltage allowed by the bus capacitor are obtained. U ref .

[0042] In some embodiments, the current capacitor voltage of the bus capacitor may be detected by a sensor, and the current capacitor voltage of the bus capacitor may be acquired from the sensor.

[0043] In some embodiments, the preset minimum allowable voltage of the capacitor can be obtained from a memory storing the preset minimum allowable voltage of the bus capacitor, or the preset minimum allowable voltage of the capacitor can be obtained from a cloud server, etc.

[0044] The preset capacitance of the bus capacitor allows the lowest voltage U refRefers to the lowest voltage allowed by the bus capacitor, which is determined by the maximum allowable input voltage of the power grid. U ref It is obtained by theoretical calculation of the AC grid voltage value. Usually, the output voltage of the PFC circuit 10 is 1.414 times the maximum effective value of the AC grid. Therefore, the bus capacitor can be allowed to have a minimum voltage of U ref Set to 1.414 times the maximum effective voltage of the AC grid.

[0045] In step S24, if the current capacitor voltage is lower than the preset capacitor allowable minimum voltage, the bus capacitor voltage is increased by reducing the resonant gain of the isolated DC / DC circuit until it is detected that the bus capacitor voltage reaches the preset capacitor allowable minimum voltage.

[0046] By adopting the above technical solution, when the current capacitor voltage is lower than the preset minimum allowable capacitor voltage, the voltage of the bus capacitor can be increased by reducing the resonant gain of the isolated DC / DC circuit, thereby avoiding the situation where the voltage of the bus capacitor is lower than the preset minimum allowable capacitor voltage, and the voltage difference between the voltage output to the bus capacitor through the PFC circuit and the actual voltage of the bus capacitor causes uncontrolled rectification, thereby improving the service life of related components in the on-board charger and improving the charging safety of on-board charging.

[0047] Figure 4 FIG. 1 is another flow chart of a control method of a vehicle charger according to an embodiment of the present disclosure. Figure 4 As shown, the control method is Figure 3 Step S25 is added on the basis of.

[0048] In step S25, if the current capacitor voltage is greater than or equal to the preset capacitor allowable minimum voltage, the PFC circuit is controlled to output a constant current, and the isolated DC / DC circuit is open-loop controlled through a preset resonant frequency.

[0049] Since the current capacitor voltage is greater than or equal to the preset capacitor's minimum allowable voltage, this means that the voltage difference between the current bus voltage of the bus capacitor and the bus voltage obtained by linkage is not sufficient to cause uncontrolled rectification. Therefore, in this case, the PFC circuit can be controlled to output a constant current, and the isolated DC / DC circuit can be controlled by open-loop control.

[0050] In this embodiment, when the voltage of the bus capacitor is equal to the minimum allowable voltage of the preset capacitor, the isolated DC / DC circuit is open-loop controlled, that is, only the switch tube of the PFC module needs to be controlled, which reduces the switching loss of the on-board charger and the overall control complexity of the on-board charger, thereby improving the control safety.

[0051] It should be noted that, in this embodiment, there are various ways to reduce the resonance gain of the isolated DC / DC circuit.

[0052] In some embodiments, the isolated DC / DC circuit 20 includes a first conversion module, a transformer module, and a second conversion module connected in sequence, wherein the first conversion module is connected to the PFC circuit 10, and the second conversion module is connected to the power battery 3. Then, reducing the resonance gain of the isolated DC / DC circuit 20 to increase the voltage of the bus capacitor may include: reducing the duty cycle of the first conversion module of the isolated DC / DC circuit 20 to reduce the resonance gain of the isolated DC / DC circuit 20 to increase the voltage of the bus capacitor. Figure 5 The schematic diagram of the on-board charger circuit shown is used as an example for explanation.

[0053] exist Figure 5 In the embodiment, the PFC circuit 10 includes an inductor L1, a switch T1, a switch T2, a switch T3 and a switch T4; the bus capacitor includes a capacitor C1; the isolated DC / DC circuit 20 includes a switch T5, a switch T6, a switch T7, a switch T8, a resonant inductor L2, a resonant capacitor C2, a transformer M1, a diode D1, a diode D2, a diode D3, a diode D4 and an output capacitor C3. Among them, the switch T5, the switch T6, the switch T7, the switch T8, the resonant inductor L2 and the resonant capacitor C2 constitute the first conversion module of the isolated DC / DC circuit 20; the transformer module of the isolated DC / DC circuit 20 is composed of the transformer M1. The second conversion module of the isolated DC / DC circuit 20 is composed of diodes D1 to D4 and a capacitor C3.

[0054] Figure 5 In the embodiment, the resonant frequency of the first conversion module is determined by the resonant inductor L2 and the resonant capacitor C2. By reducing the duty cycle of the switch T5, the switch T6, the switch T7, and the switch T8, the resonant gain of the isolated DC / DC circuit 20 is reduced. For example, assuming that the resonant gain of the isolated DC / DC circuit 20 is 1:1, the resonant gain is reduced to, for example, 1.5:1 by reducing the duty cycle.

[0055] By adopting the above-mentioned technical solution, the resonant gain of the isolated DC / DC circuit 20 can be reduced by reducing the duty cycle of the switch tube in the first conversion module of the isolated DC / DC circuit 20 to increase the voltage of the bus capacitor. That is, the present application can achieve the increase of the bus voltage by reducing the duty cycle of the switch tube, simplify the control strategy, and thus improve the control rate and control safety.

[0056] In some embodiments, increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit can include: controlling the first conversion module of the isolated DC / DC circuit to switch from a full-bridge control mode to a half-bridge control mode to reduce the resonant gain of the isolated DC / DC circuit to increase the voltage of the bus capacitor.

[0057] Still Figure 5 Take the circuit schematic diagram shown as an example. The resonance gain of the isolated DC / DC circuit 20 can be reduced by switching the switch T5, switch T6, switch T7, and switch T8 from the full-bridge control mode to the half-bridge control mode. For example, the first conversion module of the isolated DC / DC circuit 20 can be operated in the half-bridge control mode by making the switch T7 normally off and the switch T8 normally on, and controlling the duty cycle of the switch T5 and the switch T6, so that the resonance gain of the first conversion module of the isolated DC / DC circuit can be reduced, thereby achieving the purpose of increasing the voltage of the bus capacitor.

[0058] Figure 6 FIG. 1 is a schematic block diagram of a vehicle charger according to an embodiment of the present disclosure. Figure 6 As shown, the on-board charger 1 includes a PFC circuit 10, a bus capacitor C1 and an isolated DC / DC circuit 20, a first output end of the PFC circuit 10 is connected to a first input end of the isolated DC / DC circuit 20, a second output end of the PFC circuit 10 is connected to a second input end of the isolated DC / DC circuit 20, the bus capacitor C1 is connected between the first output end and the second output end of the PFC circuit 10, and the voltage of the bus capacitor C1 is linked to the voltage of the power battery 3.

[0059] like Figure 6 As shown, the on-board charger 1 also includes: an acquisition module 30, which is used to acquire the preset battery allowable minimum voltage of the power battery 3 and the current battery voltage of the power battery 3 when the grid access is detected; a control module 40, which is used to increase the voltage of the bus capacitor C1 by reducing the resonant gain of the isolated DC / DC circuit 20 if the current battery voltage is lower than the preset battery allowable minimum voltage, until it is detected that the voltage of the power battery 3 reaches the preset battery allowable minimum voltage.

[0060] In this embodiment, since the voltage of the bus capacitor is linked to the voltage of the power battery, when the voltage of the power battery is low, the first voltage of the linked bus capacitor is also low. However, after connecting to the power grid, the second voltage output to the bus capacitor through the PFC circuit may be relatively high. Therefore, there is a large voltage difference between the first voltage and the second voltage. The large voltage difference will lead to uncontrolled rectification and even abnormally large current, thereby damaging related electronic devices in the on-board charger.

[0061] In order to avoid the occurrence of uncontrolled rectification, when the present application detects grid access, when the current battery voltage is lower than the preset minimum allowable battery voltage, the voltage of the bus capacitor is increased by reducing the resonant gain of the isolated DC / DC circuit until the voltage of the power battery is detected to reach the preset minimum allowable battery voltage, so that the voltage of the bus capacitor can be automatically increased, thereby causing the difference between the first voltage and the second voltage to be smaller, thereby effectively avoiding the occurrence of uncontrolled rectification and the generation of abnormally large current.

[0062] In addition, since the voltage of the bus capacitor is linked to the voltage of the power battery, the voltage of the bus capacitor will not fluctuate greatly, so there is no need to set an electrolytic capacitor with a withstand voltage value (that is, the maximum rated voltage of the capacitor does not need to be set very high), and thus the application can use a small-capacity film capacitor as the bus capacitor, thereby improving the high-temperature resistance of the bus capacitor. Since the capacitance of the bus capacitor is reduced, the equivalent series resistance can be reduced, the overall efficiency can be improved, and the cost can be reduced.

[0063] On the basis of this embodiment, in other embodiments, the acquisition module 30 is also used to obtain the current capacitor voltage of the bus capacitor and the preset minimum capacitor allowable voltage of the bus capacitor after the voltage of the power battery reaches the preset battery allowable minimum voltage; the control module 40 is also used to increase the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit if the current capacitor voltage is lower than the preset minimum capacitor allowable voltage, until it is detected that the voltage of the bus capacitor reaches the preset minimum capacitor allowable voltage.

[0064] Based on this embodiment, in other embodiments, the control module 40 is also used to: if the current capacitor voltage is greater than or equal to the preset capacitor allowable minimum voltage, control the PFC circuit to output a constant current, and perform open-loop control of the isolated DC / DC circuit through a preset resonant frequency.

[0065] On the basis of this embodiment, in other embodiments, the isolated DC / DC circuit 20 includes a first conversion module, a transformer module, and a second conversion module connected in sequence, the first conversion module is connected to the PFC circuit, and the second conversion module is connected to the power battery; then, the control module 40 is used to: reduce the duty cycle of the first conversion module to reduce the resonant gain of the isolated DC / DC circuit, thereby increasing the voltage of the bus capacitor.

[0066] Figure 7 FIG. 2 shows a schematic diagram of a duty cycle adjustment strategy of a vehicle charger according to an embodiment of the present disclosure. Figure 7As shown, the on-board charger further includes a modulator 50, which is used to receive duty cycle information from the control module 40 and generate a duty cycle modulation signal for driving the first conversion module based on the duty cycle information. Figure 5 Taking the circuit diagram of as an example, the duty cycle modulation signal will be used to control switch T5, switch T6, switch T7, and switch T8. By adopting the above technical solution, a modulation signal for controlling the duty cycle can be generated.

[0067] Figure 8 is a schematic logic diagram of a control PFC circuit according to an embodiment of the present disclosure, in which: u a Indicates the voltage of the AC grid, ia represents the output current of the AC grid, i a_ref represents the output target current of the AC power grid, I a_ref Indicates the effective output current of the AC power grid. Figure 8 The control logic shown can control the PFC circuit 10 to output a constant current.

[0068] Specifically, extract the phase information in ua, the phase information and I a_ref confirm i a_ref , and then according to i a_ref and ia The difference information is fed back to the controller, and the controller outputs a modulated PWM to the PFC circuit according to the difference information to control the constant current output of the PFC circuit.

[0069] The specific implementation of the operation of the relevant modules of the on-board charger according to the embodiment of the present disclosure has been described in detail in the relevant method and will not be repeated here.

[0070] According to yet another embodiment of the present disclosure, a vehicle is provided, comprising the on-board charger according to the embodiment of the present disclosure.

[0071] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0072] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0073] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A control method for an on-board charger, the on-board charger comprising a PFC circuit, a bus capacitor and an isolated DC / DC circuit, wherein a first output end of the PFC circuit is connected to a first input end of the isolated DC / DC circuit, a second output end of the PFC circuit is connected to a second input end of the isolated DC / DC circuit, and the bus capacitor is connected between the first output end and the second output end of the PFC circuit, characterized in that: The voltage of the bus capacitor is linked to the voltage of the power battery, and the control method includes: When grid access is detected, obtaining a preset minimum allowable battery voltage of the power battery and a current battery voltage of the power battery; If the current battery voltage is lower than the preset minimum allowable battery voltage, the voltage of the bus capacitor is increased by reducing the resonant gain of the isolated DC / DC circuit to reduce the difference between the first voltage and the second voltage until it is detected that the voltage of the power battery reaches the preset minimum allowable battery voltage, wherein the first voltage is the bus capacitor voltage generated due to the linkage between the voltage of the bus capacitor and the voltage of the power battery, and the second voltage is the voltage output by the power grid to the bus capacitor via the PFC circuit.

2. The control method according to claim 1, characterized in that: After the step of detecting that the voltage of the power battery reaches the preset minimum allowable voltage of the battery, the control method further includes: Acquire the current capacitance voltage of the bus capacitor and the preset capacitance allowable minimum voltage of the bus capacitor; If the current capacitor voltage is lower than the preset minimum capacitor voltage, the voltage of the bus capacitor is increased by reducing the resonant gain of the isolated DC / DC circuit to reduce the voltage difference between the voltage output from the grid to the bus capacitor via the PFC circuit and the current capacitor voltage of the bus capacitor, until it is detected that the voltage of the bus capacitor reaches the preset minimum capacitor voltage.

3. The control method according to claim 2, characterized in that: After the step of obtaining the current capacitor voltage of the bus capacitor and the preset capacitor allowable minimum voltage of the bus capacitor, the control method further includes: If the current capacitor voltage is greater than or equal to the preset capacitor allowable minimum voltage, the PFC circuit is controlled to output a constant current, and the isolated DC / DC circuit is open-loop controlled through a preset resonant frequency.

4. The control method according to claim 1 or 2, characterized in that: The isolated DC / DC circuit includes a first conversion module, a voltage transformation module, and a second conversion module connected in sequence, the first conversion module is connected to the PFC circuit, and the second conversion module is connected to the power battery; then, the step of increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit includes: The duty cycle of the first conversion module is reduced to reduce the resonance gain of the isolated DC / DC circuit, thereby increasing the voltage of the bus capacitor.

5. The control method according to claim 1 or 2, characterized in that: The isolated DC / DC circuit includes a first conversion module, a voltage transformation module, and a second conversion module connected in sequence, the first conversion module is connected to the PFC circuit, and the second conversion module is connected to the power battery; then, the step of increasing the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit includes: The voltage of the bus capacitor is increased by controlling the first conversion module to switch from a full-bridge control mode to a half-bridge control mode to reduce the resonant gain of the isolated DC / DC circuit.

6. The control method according to claim 1, characterized in that: The preset minimum allowable battery voltage is determined according to the maximum allowable input voltage of the power grid and the transformer turns ratio.

7. The control method according to claim 2, characterized in that: The preset capacitor allows the lowest voltage to be determined according to the maximum allowable input voltage of the power grid.

8. A vehicle charger, comprising a PFC circuit, a bus capacitor and an isolated DC / DC circuit, wherein a first output end of the PFC circuit is connected to a first input end of the isolated DC / DC circuit, a second output end of the PFC circuit is connected to a second input end of the isolated DC / DC circuit, and the bus capacitor is connected between the first output end and the second output end of the PFC circuit, characterized in that: The voltage of the bus capacitor is linked to the voltage of the power battery, and the on-board charger further includes: An acquisition module, used for acquiring a preset battery allowable minimum voltage of the power battery and a current battery voltage of the power battery when a power grid access is detected; A control module is used for increasing the voltage of the bus capacitor by reducing the resonance gain of the isolated DC / DC circuit to reduce the difference between the first voltage and the second voltage if the current battery voltage is lower than the preset minimum allowable battery voltage, until it is detected that the voltage of the power battery reaches the preset minimum allowable battery voltage, wherein the first voltage is the bus capacitor voltage generated due to the linkage between the voltage of the bus capacitor and the voltage of the power battery, and the second voltage is the voltage output by the power grid to the bus capacitor via the PFC circuit.

9. The vehicle-mounted charger according to claim 8, characterized in that: The acquisition module is further configured to acquire the current capacitor voltage of the bus capacitor and the preset minimum capacitor voltage of the bus capacitor after the voltage of the power battery reaches the preset minimum battery voltage; The control module is further configured to increase the voltage of the bus capacitor by reducing the resonant gain of the isolated DC / DC circuit to reduce the voltage difference between the voltage output from the power grid to the bus capacitor via the PFC circuit and the current capacitor voltage of the bus capacitor if the current capacitor voltage is lower than the preset capacitor minimum allowable voltage, until it is detected that the bus capacitor voltage reaches the preset capacitor minimum allowable voltage.

10. A vehicle, characterized in that: The vehicle-mounted charger comprises the vehicle-mounted charger according to any one of claims 8 to 9.

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