Energy reflux discharging method, on-vehicle charging system and electric vehicle

Abstract

The present application discloses an energy reflux discharging method, an on-vehicle charging system and an electric vehicle. Among them, the energy reflux discharging method includes: when receiving an end charging instruction, obtaining the confirmed charging mode identified during charging connection; judging whether it is single-phase charging or three-phase charging according to the confirmed charging mode; when it is determined to be single-phase charging, controlling the on-vehicle charging device to execute a preset single-phase discharging strategy to discharge the energy of multiple capacitor modules and reflux it to the power battery or the storage battery; when it is determined to be three-phase charging, controlling the on-vehicle charging device to execute a preset three-phase discharging strategy to discharge the energy of multiple capacitor modules and reflux it to the power battery or the storage battery. Different charging modes and different discharging strategies improve the discharging rate; the energy refluxes to the power battery or the storage battery, improving the effective utilization rate of energy.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and particularly to an energy return discharge method, an on-vehicle charging system, and an electric vehicle. Background Art

[0002] With the popularization of electric vehicles, users can accept different charging durations in different usage environments. For example, they can accept a longer charging time during non-working hours (10:00 pm - 6:00 am), and in case of an emergency, they expect to complete charging within a short period (for example, complete charging within half an hour). Therefore, an on-vehicle charger that supports both single-phase charging and three-phase charging has emerged as the times require.

[0003] However, when the charging gun is pulled out from the charging port of the above on-vehicle charger, the discharge time of the capacitor voltage at the charging port is relatively long, thus there is a risk of endangering the personal safety of users. Therefore, it is an urgent technical problem to be solved currently to propose a discharge method for quickly discharging the energy of the capacitor at the charging port. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the first object of the present invention is to propose an energy return discharge method, which adopts different discharge strategies for different charging modes to ensure quick discharge in different charging modes, and returns the discharged energy to the power battery or storage battery to improve the effective utilization rate of energy.

[0005] To achieve the above object, according to an embodiment of the first aspect of the present invention, an energy return discharge method is proposed, which is applied to an on-vehicle charging device provided with a plurality of capacitor modules at the charging port. The energy return discharge method includes:

[0006] When receiving an end charging instruction, obtain the confirmed charging mode identified during charging connection;

[0007] Judge whether it is single-phase charging or three-phase charging according to the confirmed charging mode;

[0008] When it is determined to be single-phase charging, control the on-vehicle charging device to execute a preset single-phase discharge strategy to discharge and return the energy of the plurality of capacitor modules to the power battery or storage battery;

[0009] When it is determined to be three-phase charging, control the on-vehicle charging device to execute a preset three-phase discharge strategy to discharge and return the energy of the plurality of capacitor modules to the power battery or storage battery.

[0010] In a further implementation, the on-vehicle charging device includes an EMI module, a PFC module, a first DC-DC module, and a second DC-DC module. The first end of the EMI module is connected to an external power supply, the second end of the EMI module is connected to the first end of the PFC module, the second end of the PFC module is connected to the first end of the first DC-DC module, the second end of the first DC-DC is respectively connected to the first end of the second DC-DC module and the power battery, the second end of the second DC-DC module is connected to the storage battery, and at least three X-capacitor modules are provided at the charging port. The PFC module includes three-phase bridge arms, and each phase bridge arm corresponds to an X-capacitor module;

[0011] The above step of, when it is determined to be single-phase charging, controlling the on-vehicle charging device to execute a preset single-phase discharge strategy to discharge the energy of multiple capacitors back to the power battery or the storage battery includes:

[0012] When it is determined to be single-phase charging, obtain a first voltage value corresponding to the X-capacitor module corresponding to the conducting phase bridge arm in the three-phase bridge arm;

[0013] Judge whether the first voltage value exceeds a first preset threshold;

[0014] When the first voltage value exceeds the first preset threshold, obtain a second voltage value across the storage battery;

[0015] When the second voltage value does not exceed a second preset threshold, control the PFC module, the first DC-DC module, and the second DC-DC module to execute a preset single-phase discharge strategy to discharge the energy of the X-capacitor module back to the storage battery.

[0016] In a further implementation, after the above step of obtaining the second voltage value across the storage battery, it further includes:

[0017] When the second voltage value exceeds the second preset threshold, control the PFC module and the first DC-DC module to execute a preset single-phase discharge strategy to discharge the energy of the X-capacitor module back to the power battery.

[0018] In a further embodiment, the above step of, when it is determined to be three-phase charging, controlling the on-vehicle charging device to execute a preset three-phase discharge strategy to discharge the energy of multiple capacitors back to the power battery or the storage battery includes:

[0019] When it is determined to be three-phase charging, obtain a third voltage value of each X-capacitor module;

[0020] Judge whether the third voltage values of the three X-capacitor modules do not exceed the first preset threshold;

[0021] When it is determined that at least one of the third voltage values of the three X-capacitor modules exceeds the first preset threshold, obtain a fourth voltage value across the storage battery;

[0022] When the fourth voltage value does not exceed the second preset threshold, the PFC module, the first DC-DC module, and the second DC-DC module are controlled to execute a preset three-phase discharging strategy to discharge the energy of the X-capacitor module back to the storage battery.

[0023] In a further embodiment, the PFC module further includes three inductors and a bus capacitor, and each inductor is correspondingly connected to a phase leg; the step of controlling the PFC module, the first DC-DC module, and the second DC-DC module to execute a preset three-phase discharging strategy to discharge the energy of the X-capacitor module back to the storage battery includes:

[0024] Continuously control the upper switching tubes of the three-phase legs of the PFC module to turn off simultaneously, and control the lower switching tubes of the lower three-phase legs of the PFC module to turn on simultaneously for a preset first time period to store the energy of the X-capacitor module into the inductor;

[0025] Continuously control the upper switching tubes of the three-phase legs of the PFC module to turn on simultaneously, and control the lower switching tubes of the lower three-phase legs of the PFC module to turn off simultaneously for a preset second time period to store the energy of the inductor into the bus capacitor;

[0026] Control the first DC-DC module at the resonant frequency of the first DC-DC module and start the second DC-DC module to store the energy of the bus capacitor into the storage battery, and repeat the above operation until the voltage value of the X-capacitor module does not exceed the first preset threshold.

[0027] In a further embodiment, after the step of obtaining the fourth voltage value across the storage battery, it further includes:

[0028] When the fourth voltage value exceeds the second preset threshold, control the PFC module and the first DC-DC module to execute a preset three-phase discharging strategy to discharge the energy of the X-capacitor module back to the power battery.

[0029] In a further embodiment, the PFC module further includes three inductors and a bus capacitor, and each inductor is correspondingly connected to a phase leg; the step of controlling the PFC module and the first DC-DC module to execute a preset three-phase discharging strategy includes:

[0030] Continuously control the upper switching tubes of the three-phase legs of the PFC module to turn off simultaneously, and control the lower switching tubes of the lower three-phase legs of the PFC module to turn on simultaneously for a preset first time period to discharge and store the energy of the X-capacitor module into the inductor;

[0031] Continuously control the upper switching tubes of the three-phase legs of the PFC module to turn on simultaneously, and control the lower switching tubes of the lower three-phase legs of the PFC module to turn off simultaneously for a preset first time period to store the energy of the inductor into the bus capacitor;

[0032] Control the first DC-DC module at the resonance frequency of the first DC-DC module to store the energy of the bus capacitor into the power battery, and repeat the above operation until the voltage value of the X-capacitor module does not exceed the first preset threshold.

[0033] In a further embodiment, before the step of receiving the end charging instruction described above, it further includes:

[0034] When receiving a charging connection instruction, identify whether the external power supply is a single-phase power supply or a three-phase power supply, and start a single-phase charging mode and record it or start a three-phase charging mode and record it according to the identification result.

[0035] In a further embodiment, the step of identifying whether the external power supply is a single-phase power supply or a three-phase power supply, and starting a single-phase charging mode and recording it or starting a three-phase charging mode and recording it according to the identification result includes:

[0036] Obtain the first phase and the first effective voltage value corresponding to the first phase leg, the second phase and the second effective voltage value corresponding to the second phase leg, and the third phase and the third effective voltage value corresponding to the third phase leg;

[0037] Obtain the first phase difference between the first phase and the second phase, the second phase difference between the second phase and the third phase, and the third phase difference between the third phase and the first phase;

[0038] Judge whether the external power supply is a single-phase power supply or a three-phase power supply according to the first phase difference, the second phase difference, the third phase difference, the first effective voltage value, the second effective voltage value, and the third effective voltage value;

[0039] If it is determined that the external power supply is a single-phase power supply, start a single-phase charging mode and record it;

[0040] If it is determined that the external power supply is a three-phase power supply, start a three-phase charging mode and record it.

[0041] The second object of the present invention is to propose a vehicle-mounted charging system, which includes a vehicle-mounted charging device and a controller connected to the vehicle-mounted charging device, and the controller is used to control the vehicle-mounted charging device to execute the energy return discharge method described in the above embodiments.

[0042] The third object of the present invention is to propose a vehicle, which includes the vehicle-mounted charging system described in the above embodiments.

[0043] Compared with the existing related technologies, the present embodiment has the following beneficial effects:

[0044] (1) In different charging modes, the number of X-capacitor modules entering the working state is different. Therefore, the number of X-capacitor modules with voltage after unplugging the gun is also different. Thus, when charging ends, different discharging strategies are adopted according to different charging modes to ensure that the X-capacitor modules entering the working state are discharged synchronously, thereby improving the energy discharge rate of the capacitors. Furthermore, the energy of the X-capacitor modules at the charging port will be quickly discharged after unplugging the gun, reducing the risk that the energy of the X-capacitor modules is output through the charging port and endangering personal safety.

[0045] (2) The X-capacitor modules at the charging port flow back to the power battery or the storage battery to achieve energy recovery, thereby improving the effective utilization rate of energy.

[0046] (3) The charging mode is confirmed and recorded during charging connection. Therefore, when charging ends, the confirmed charging mode recorded can be directly retrieved, and there is no need to identify the charging mode again. Thus, both the discharging control strategy is streamlined and the discharging control rate is improved.

[0047] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0048] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0049] Figure 1 is a schematic diagram of the frame structure of the on-vehicle charging system according to the first embodiment of the present invention;

[0050] Figure 2 is a schematic diagram of the frame structure of the on-vehicle charging system according to the second embodiment of the present invention;

[0051] Figure 3 is Figure 2 a schematic diagram of the structure of the switch module in

[0052] Figure 4 is a schematic diagram of the flow of the energy reflux discharging method according to the first embodiment of the present invention;

[0053] Figure 5 is Figure 4 a schematic diagram of the flow of the single-phase discharging strategy in

[0054] Figure 6 is Figure 4 a schematic diagram of the flow of the three-phase discharging strategy in

[0055] Figure 7 is Figure 6 a schematic diagram of the flow of the three-phase discharging strategy for energy reflux to the storage battery in

[0056] Figure 8 is Figure 6 a schematic flow chart of a three-phase discharge strategy for medium energy to flow back to the power battery;

[0057] Figure 9 is a schematic flow chart of the energy backflow discharge method according to the second embodiment of the present invention;

[0058] Figure 10 is Figure 9 a schematic flow chart of the charging mode recognition process in Detailed Embodiments

[0059] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0060] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0061] In the description of the present invention, "a plurality of" means two or more, and "several" means one or more.

[0062] The on-vehicle charging system according to an embodiment of the present invention will be described below with reference to the drawings.

[0063] As Figure 1 shown, the on-vehicle charging system includes an EMI module 1, a PFC module 2, a first DC-DC module 3, a second DC-DC module 4, and a controller 5. The first end of the EMI module 1 is connected to an external power supply, the second end of the EMI module 1 is connected to the first end of the PFC module 2, the second end of the PFC module 2 is connected to the first end of the first DC-DC module 3, the second end of the first DC-DC module 3 is respectively connected to the first end of the second DC-DC module 4 and the power battery, and the second end of the second DC-DC module 4 is connected to the storage battery.

[0064] Among them, the EMI module 1 includes a filter, and at least three X-capacitor modules are provided at the charging port. These three X-capacitor modules are capacitor CX1, capacitor CX2, and capacitor CX3. Part or all of the first end of the first lead L1, the first end of the second lead L2, the first end of the third lead L3, and the first end of the fourth lead N can be connected to an external power supply through a charging gun. Specifically, when single-phase charging is performed, the first end of the first lead L1 and the first end of the fourth lead N are connected to the external power supply through the charging gun. In addition, when three-phase charging is performed, the first end of the first lead L1, the first end of the second lead L2, the first end of the third lead L3, and the first end of the fourth lead N are connected to the external power supply through the charging gun.

[0065] It should be noted that the X-capacitor module in this embodiment can be a single capacitor device or a capacitor module composed of multiple capacitor devices.

[0066] Further, the second end of the first lead L1 passes through the filter and is connected to the first end of capacitor CX1, the second end of the second lead L2 passes through the filter and is connected to the first end of capacitor CX2, the second end of the third lead L3 passes through the filter and is connected to the first end of capacitor CX3, and the second end of the fourth lead N passes through the filter and is respectively connected to the second ends of capacitor CX1, capacitor CX2, and capacitor CX3.

[0067] Further, the PFC module 2 includes three power inductors, a three-phase high-frequency bridge arm (Q1-Q6), a single-phase power-frequency bridge arm (Q7 and Q8), and a bus capacitor C1. The first end of the first power inductor is connected to the first end of capacitor CX1, and the first power inductor is connected to the midpoint of the first-phase high-frequency bridge arm (i.e., Figure 1 the midpoint of Q1 and Q2 in it). The first end of the second power inductor is connected to the first end of capacitor CX2, and the second power inductor is connected to the midpoint of the second-phase high-frequency bridge arm (i.e., Figure 1 the midpoint of Q3 and Q4 in it). The first end of the third power inductor is connected to the first end of capacitor CX3, and the third power inductor is connected to the midpoint of the third-phase high-frequency bridge arm (i.e., Figure 1 the midpoint of Q5 and Q6 in it). The midpoint of the power-frequency bridge arm (i.e., Figure 1 the midpoint of Q7 and Q8 in it) is respectively connected to the second ends of capacitor CX1, capacitor CX2, and capacitor CX3. The first ends of the first-phase high-frequency bridge arm, the second-phase high-frequency bridge arm, the third-phase high-frequency bridge arm, and the power-frequency bridge arm are commonly connected to form a first busbar end, and the second ends of the first-phase high-frequency bridge arm, the second-phase high-frequency bridge arm, the third-phase high-frequency bridge arm, and the power-frequency bridge arm are commonly connected to form a second busbar end. The bus capacitor C1 is disposed between the first busbar end and the second busbar end.

[0068] Further, the first DC-DC module 3 includes a first H-bridge (Q9-Q12), a transformer 1, and a second H-bridge (Q13-Q16). The first end of the first H-bridge is connected to the PFC module 2, the second end of the first H-bridge is connected to one side of the transformer 1, the first end of the second H-bridge is connected to the other side of the transformer 1, and the second end of the second H-bridge is respectively connected to the second DC-DC module 4 and the power battery. It should be noted that the first DC-DC module 3 in this embodiment is a conventional bidirectional DC-DC module. Therefore, all bidirectional DC-DC modules in the related art are within the protection scope of the embodiments of the present invention. At the same time, the connection relationship between the first DC-DC module 3 and the PFC module 2, and the connection relationship between the first DC-DC module 3 and the power battery in this embodiment are both conventional technologies. Therefore, the connection relationship is not described in detail in this embodiment.

[0069] Further, the second DC-DC module 4 includes a third H-bridge (Q17-Q20), a transformer 2, and a fourth H-bridge (Q21 and Q22). The first end of the third H-bridge is respectively connected to the second end of the second H-bridge and the power battery. The second end of the third H-bridge is connected to one side of the transformer 2. The other side of the transformer 2 is connected to the first end of the fourth H-bridge, and the second end of the fourth H-bridge is connected to the storage battery. It should be noted that the second DC-DC module 4 in this embodiment is a conventional low-voltage DC-DC module. Therefore, all low-voltage DC-DC modules in the related art are within the protection scope of the embodiments of the present invention. At the same time, the connection relationship between the second DC-DC module 4 and the first DC-DC module 3, and the connection relationship between the second DC-DC module 4 and the storage battery in this embodiment are both conventional technologies. Therefore, the connection relationship is not described in detail in this embodiment.

[0070] Further, the controller 5 is respectively connected to the PFC module 2, the first DC-DC module 3, and the second DC-DC module 4.

[0071] The on-vehicle charging system of this embodiment is applied to implement the following functions:

[0072] 1. Identification of charging mode

[0073] When it is detected that the charging gun is inserted into the charging port, a charging connection command will be generated. When the controller 5 receives the charging connection command, it will identify whether the external power supply is a single-phase power supply or a three-phase power supply, and start the single-phase charging mode and record it or start the three-phase charging mode and record it according to the identification result.

[0074] Specifically, the controller 5 is used to obtain the first phase and the first effective voltage value corresponding to the first phase bridge arm, the second phase and the second effective voltage value corresponding to the second phase bridge arm, and the third phase and the third effective voltage value corresponding to the third phase bridge arm collected by the sensor.

[0075] The controller 5 is also configured to calculate a first phase difference between the first phase and the second phase, a second phase difference between the second phase and the third phase, and a third phase difference between the third phase and the first phase.

[0076] The controller 5 is also configured to determine whether the external power supply is a single-phase power supply or a three-phase power supply according to the first phase difference, the second phase difference, the third phase difference, the first effective voltage value, the second effective voltage value, and the third effective voltage value. If it is determined that the external power supply is a single-phase power supply, the single-phase charging mode is started and recorded; if it is determined that the external power supply is a three-phase power supply, the three-phase charging mode is started and recorded.

[0077] Specifically, on the basis of this embodiment, in other embodiments, the implementation of the above embodiment at least includes the following several situations:

[0078] (1) Identify single-phase and three-phase through phase difference first, and then identify single-phase and three-phase through effective voltage value

[0079] Specifically, first identify single-phase and three-phase through phase difference. When the identification of single-phase charging and three-phase charging cannot be achieved through phase difference, then identify single-phase and three-phase through effective voltage value.

[0080] (2) Identify single-phase and three-phase through effective voltage value first, and then identify single-phase and three-phase through phase difference

[0081] Specifically, first identify single-phase and three-phase through effective voltage value. When the identification of single-phase charging and three-phase charging cannot be achieved through effective voltage value, then identify single-phase and three-phase through phase difference.

[0082] (3) Identify single-phase or three-phase through phase difference first, and then identify single-phase and three-phase through effective voltage value

[0083] Specifically, first identify single-phase through phase difference. When the identification of single-phase charging cannot be achieved through phase difference, then identify single-phase and three-phase through effective voltage value.

[0084] In addition, first identify three-phase through phase difference. When the identification of three-phase charging cannot be achieved through phase difference, then identify single-phase and three-phase through effective voltage value.

[0085] (4) Identify single-phase or three-phase through effective voltage value first, and then identify single-phase and three-phase through phase difference

[0086] Specifically, first identify single-phase through effective voltage value. When the identification of single-phase charging cannot be achieved through effective voltage value, then identify single-phase and three-phase through phase difference.

[0087] In addition, first, the three phases are identified through the effective value of the voltage. When the identification of three-phase charging cannot be achieved through the effective value of the voltage, then the single-phase and three-phase identifications are carried out through the phase difference.

[0088] In the embodiments of this case, the single-phase and three-phase identifications can be achieved through the effective value of the voltage, and the single-phase and three-phase identifications can also be carried out through the phase difference. In order to more specifically illustrate the technical solution of the present invention, therefore, the single-phase and three-phase identifications achieved through the effective value of the voltage and the single-phase and three-phase identifications carried out through the phase difference will be described in detail.

[0089] 1. Achieving single-phase and three-phase identifications through the effective value of the voltage

[0090] The controller 5 determines whether the preset single-phase determination condition or the preset three-phase determination condition is satisfied according to the first effective value of the voltage, the second effective value of the voltage, and the third effective value of the voltage. If it is determined that the preset single-phase determination condition is satisfied, the single-phase charging mode is started and recorded. If it is determined that the preset three-phase determination condition is satisfied, the three-phase charging mode is started and recorded.

[0091] Based on this embodiment, in other embodiments, the preset three-phase determination condition is: the first effective value of the voltage > the second effective value of the voltage > the third effective value of the voltage and the third effective value of the voltage > the first preset voltage threshold.

[0092] In order to more specifically describe the technical solution of the present invention, the first preset voltage threshold can be preset or can be set in real time according to user requirements. Exemplarily, the first preset voltage threshold can be 150V.

[0093] The preset single-phase determination condition is: the first effective value of the voltage > the second effective value of the voltage > the third effective value of the voltage and the second effective value of the voltage < the second preset voltage threshold.

[0094] In order to more specifically describe the technical solution of the present invention, the second preset voltage threshold can be preset or can be set in real time according to user requirements. Exemplarily, the second preset voltage threshold can be 20V.

[0095] 2. Achieving single-phase and three-phase identifications through the phase difference

[0096] The controller 5 determines whether the preset single-phase determination condition or the preset three-phase determination condition is satisfied according to the first phase difference, the second phase difference, and the third phase difference; if it is determined that the preset single-phase determination condition is satisfied, the single-phase charging mode is started and recorded. If it is determined that the preset three-phase determination condition is satisfied, the three-phase charging mode is started and recorded.

[0097] Based on this embodiment, in other embodiments, the preset three-phase charging determination condition is that the first phase difference, the second phase difference, and the third phase difference all fall within the preset phase range.

[0098] To describe the technical solution of the present invention in more detail, the preset phase range can be pre-set or can be set in real time according to user requirements. Exemplarily, the preset phase range can be (105°, 125°).

[0099] Based on this embodiment, in other embodiments, the preset single-phase charging determination condition is that the first phase difference, the second phase difference, and the third phase difference are all less than the preset phase threshold.

[0100] To describe the technical solution of the present invention in more detail, the preset phase threshold can be pre-set or can be set in real time according to user requirements. Exemplarily, the preset phase threshold can be 10°.

[0101] Compared with the related art, when only the phase difference is used for identification, if the phase detection is abnormal, misjudgment will occur; or when only the effective value of the voltage is used for identification, if the obtained effective value of the voltage is interfered, misjudgment will be caused. Therefore, in this embodiment, the phase difference and the effective value of the voltage are combined to identify the single-phase charging / three-phase charging mode, so that when the phase difference or the effective value of the voltage cannot be accurately identified, another identification method is used for further identification, thereby improving the identification accuracy and reducing the misjudgment rate.

[0102] 2. Selection of discharge strategy

[0103] When the controller receives the end charging instruction, it obtains the confirmed charging mode identified during charging connection; determines whether it is single-phase charging or three-phase charging according to the confirmed charging mode; when it is determined to be single-phase charging, it controls the on-vehicle charging device to execute the preset single-phase discharge strategy to discharge the energy of multiple capacitors back to the power battery or the storage battery; when it is determined to be three-phase charging, it controls the on-vehicle charging device to execute the preset three-phase discharge strategy to discharge the energy of multiple capacitors back to the power battery or the storage battery.

[0104] 2.1 Execution of the preset single-phase discharge strategy

[0105] When it is determined to be single-phase charging, referring to Figure 1 , only the first lead L1 and the fourth lead N are connected to the external power supply, and only the first-phase bridge arm (Q1 and Q2) in the three-phase bridge arm is turned on.

[0106] The controller is used to obtain the first voltage value of the capacitor CX1 connected to the first-phase bridge arm, and determine whether the first voltage value exceeds the first preset threshold; when the first voltage value exceeds the first preset threshold, obtain the second voltage value across the battery; when the second voltage value does not exceed the second preset threshold (i.e., the battery has less power), control the PFC module, the first DC-DC module, and the second DC-DC module to execute a preset single-phase discharging strategy to discharge the energy of the X-capacitor module back to the battery; when the second voltage value exceeds the second preset threshold (i.e., the battery has more power), control the PFC module and the first DC-DC module to execute a preset single-phase discharging strategy to discharge the energy of the X-capacitor module back to the power battery.

[0107] In addition, referring to Figure 2 , a switch module 6 is provided between the EMI module 1 and the PFC module 2, and this switch module 6 is used to implement single-phase charging, single-phase interleaved charging, and three-phase charging.

[0108] Specifically, referring to Figure 3 , this switch module 6 includes 4 input terminals and 4 output terminals. The first end of the first input terminal is connected to the L1 lead, and the second terminal of the first input terminal is provided with a moving terminal K1 and a moving terminal K2. The first output terminal can be selectively connected to the moving terminal K1 and the moving terminal K2. The first end of the second input terminal is connected to the L2 lead, and the second terminal of the second input terminal is provided with a moving terminal K3 and a moving terminal K4. The second output terminal can be selectively connected to the moving terminal K3 and the moving terminal K4. The first end of the third input terminal is connected to the L3 lead, and the second terminal of the third input terminal is provided with a moving terminal K5 and a moving terminal K6. The third output terminal can be selectively connected to the moving terminal K5 and the moving terminal K6. The fourth input terminal is connected to the N lead, and the fourth output terminal is connected to the midpoint of the industrial frequency bridge arm.

[0109] 2.1.1. Single-phase charging

[0110] When one of the L1 lead, L2 lead, and L3 lead is conducting, and the N line is conducting, then this embodiment realizes single-phase charging. Exemplarily, when the first output terminal S1 is connected to the moving terminal K1, the second output terminal S2 is connected to the moving terminal K3, and the third output terminal S3 is neither connected to the moving terminal K5 nor the moving terminal K6, then single-phase charging connection is realized, and the connection relationships of other single-phase chargings are all within the protection scope of the present invention.

[0111] In the case of this embodiment, the execution of the preset single-phase discharging strategy is the same as that of the embodiment shown in Figure 1 , so it will not be elaborated here.

[0112] 2.1.2. Single-phase interleaved charging

[0113] When at least two of the L1 lead, L2 lead, and L3 lead are conducting, and the N lead is conducting, then single-phase interleaved charging is achieved in this embodiment. Exemplarily, when the first output terminal S1 is connected to the moving terminal K1, the second output terminal S2 is connected to the moving terminal K4, and the third output terminal S3 is not connected to either the moving terminal K5 or the moving terminal K6, then single-phase two-phase interleaved charging connection is achieved. Other single-phase two-phase interleaved charging connection relationships, and even single-phase three-phase interleaved connection relationships are within the protection scope of this embodiment.

[0114] A description of the execution of a preset single-phase discharge strategy is given by taking the single-phase two-phase interleaved charging example.

[0115] The controller is used to obtain the first voltage value of the capacitor CX1 connected to the first-phase bridge arm and the second voltage value of the capacitor CX2 connected to the second-phase bridge arm.

[0116] Judge whether the first voltage value exceeds the first preset threshold, or whether the second voltage value exceeds the first preset value; when the first voltage value exceeds the first preset threshold, or the second voltage value exceeds the first preset threshold, obtain the third voltage value across the battery; when the third voltage value does not exceed the second preset threshold (i.e., the battery has less power), then control the PFC module 2, the first DC-DC module 3, and the second DC-DC module 4 to execute the preset single-phase discharge strategy to discharge the energy of the capacitor CX1 and the capacitor CX2 back to the battery; when the second voltage value exceeds the second preset threshold (i.e., the battery has more power), then control the PFC module 2 and the first DC-DC module 3 to execute the preset single-phase discharge strategy to discharge the energy of the capacitor CX1 and the capacitor CX2 back to the power battery.

[0117] 2.2. Execution of the preset three-phase discharge strategy

[0118] When it is determined that three-phase charging is taking place, obtain the third voltage value of each X capacitor;

[0119] Judge whether the third voltage values of the three X capacitors all do not exceed the first preset threshold;

[0120] When it is determined that at least one of the third voltage values of the three X capacitors exceeds the first preset threshold, obtain the fourth voltage value across the battery;

[0121] When the fourth voltage value does not exceed the second preset threshold, then control the PFC module 2, the first DC-DC module 3, and the second DC-DC 4 module to execute the preset three-phase discharge strategy to discharge the energy of the X capacitor back to the battery;

[0122] When the fourth voltage value exceeds the second preset threshold, the PFC module and the first DC-DC module are controlled to execute a preset three-phase discharge strategy to discharge the energy of the X capacitor back to the power battery.

[0123] The above embodiments are described based on the on-vehicle charging system. Based on the description of the on-vehicle charging system, the energy return discharge method of the embodiments will be described in detail below.

[0124] See Figure 4 , the energy return discharge method includes the following steps:

[0125] S1, when receiving an end charging instruction, obtain the confirmed charging mode identified during charging connection.

[0126] In this embodiment, when a gun unplugging operation is detected, an end charging instruction will be generated. Specifically, the national standard stipulates that there is an RC resistor on the charging gun, which is used to identify the RC resistance value of the charging gun. If the detected RC resistance value is infinite, it is considered that the charging gun is disconnected. If the detected RC resistance value is a constant, it is considered that the charging gun has been inserted into the charging port.

[0127] S2, judge whether it is single-phase charging or three-phase charging according to the confirmed charging mode; when it is determined to be single-phase charging, step S3 is executed. When it is determined to be three-phase charging, step S4.

[0128] S3, control the on-vehicle charging device to execute a preset single-phase discharge strategy to discharge the energy of multiple capacitor modules back to the power battery or the battery.

[0129] Based on this embodiment, in other embodiments, see Figure 5 , this step S3 includes:

[0130] S30, when it is determined to be single-phase charging, obtain the first voltage value corresponding to the X capacitor module corresponding to the conducting phase bridge arm in the three-phase bridge arm.

[0131] In this embodiment, see Figure 1 , when single-phase charging, the conducting phase bridge arm can be the first phase bridge arm. See Figure 2 , when single-phase multi-phase interleaved control, the conducting phase bridge arm is the interleaved control bridge arm.

[0132] This embodiment distinguishes between single-phase charging and single-phase interleaved charging to avoid discharging the energy of only one capacitor in single-phase interleaved control, thereby further improving charging safety.

[0133] S31, judge whether the first voltage value exceeds the first preset threshold. When the first voltage value exceeds the first preset threshold, step S32 is executed.

[0134] In this embodiment, during single-phase charging, it is to determine whether the first voltage value of the capacitor CX1 corresponding to the first-phase bridge arm exceeds the first preset value. During single-phase interleaved control, it is to determine whether the voltage value of the X-capacitor module corresponding to one of the interleaved control multi-phase bridge arms exceeds the first preset threshold.

[0135] In addition, when the first voltage value does not exceed the first preset threshold, there is no need to start the preset single-phase discharge strategy. Therefore, the energy of the X-capacitor module can be dissipated by itself without control, reducing the control complexity and control cost.

[0136] S32. Obtain the second voltage value across the battery and determine whether the second voltage value exceeds the second preset threshold; when the second voltage value does not exceed the second preset threshold, execute step S33; when the second voltage value exceeds the second preset threshold, execute step S34.

[0137] S33. Then control the PFC module, the first DC-DC module, and the second DC-DC module to execute the preset single-phase discharge strategy to discharge the energy of the X-capacitor module back to the battery.

[0138] S34. Then control the PFC module and the first DC-DC module to execute the preset single-phase discharge strategy to discharge the energy of the X-capacitor module back to the power battery.

[0139] In this embodiment, the current power of the battery is intelligently analyzed based on the voltage of the battery, and then it is selected whether to return the energy to the battery or the power battery according to the power situation of the battery, avoiding affecting the battery when the battery is fully charged and still returning the energy to the battery, thereby shortening the service life of the battery.

[0140] S4. Control the on-vehicle charging device to execute the preset three-phase discharge strategy to discharge the energy of multiple capacitor modules back to the power battery or the battery.

[0141] Based on this embodiment, in other embodiments, refer to Figure 6 This step S4 includes:

[0142] S40. When it is determined to be three-phase charging, obtain the third voltage value of each X-capacitor module.

[0143] S41. Determine whether the third voltage values of the three X-capacitor modules do not exceed the first preset threshold; when it is determined that at least one of the third voltage values of the three X-capacitor modules exceeds the first preset threshold, execute step S42.

[0144] In this embodiment, when it is determined that the third voltage values of the three X-capacitor modules do not exceed the first preset threshold, there is no need to activate the preset three-phase discharging strategy. Therefore, the energy of the X-capacitor module can be dissipated by itself without control, reducing the control complexity and control cost.

[0145] Step S42: Obtain the fourth voltage value across the battery and determine whether the fourth voltage value exceeds the second preset threshold. When the fourth voltage value does not exceed the second preset threshold, execute step S43; when the fourth voltage value exceeds the second preset threshold, execute step S44.

[0146] Step S43: Control the PFC module, the first DC-DC module, and the second DC-DC module to execute the preset three-phase discharging strategy to discharge the energy of the X-capacitor module back to the battery.

[0147] Based on this embodiment, in other embodiments, refer to Figure 7 , this step S43 includes:

[0148] S431: Continuously control the upper switching tubes of the three-phase bridge arm of the PFC module to turn off simultaneously, and control the lower switching tubes of the lower three-phase bridge arm of the PFC module to turn on simultaneously for a preset first time period to store the energy of the X-capacitor module in the inductor.

[0149] In this embodiment, refer to Figure 1 , a body diode is connected in parallel with Q7 and Q8 in the power-frequency bridge arm. Therefore, in this embodiment, the current can conduct through the body diode. It should be noted that when neither Q7 nor Q8 in the power-frequency bridge arm is connected in parallel with a body diode, in step S431 of this embodiment, while continuously controlling the upper switching tubes of the three-phase bridge arm of the PFC module to turn off simultaneously and controlling the lower switching tubes of the lower three-phase bridge arm of the PFC module to turn on simultaneously for a preset first time period, control Q8 to turn on.

[0150] S432: Continuously control the upper switching tubes of the three-phase bridge arm of the PFC module to turn on simultaneously, and control the lower switching tubes of the lower three-phase bridge arm of the PFC module to turn off simultaneously for a preset second time period to store the energy of the inductor in the bus capacitor.

[0151] In this embodiment, refer to Figure 1 , a body diode is connected in parallel with Q7 and Q8 in the power-frequency bridge arm. Therefore, in this embodiment, the current can conduct through the body diode. It should be noted that when neither Q7 nor Q8 in the power-frequency bridge arm is connected in parallel with a body diode, in step S432 of this embodiment, while continuously controlling the upper switching tubes of the three-phase bridge arm of the PFC module to turn on simultaneously and controlling the lower switching tubes of the lower three-phase bridge arm of the PFC module to turn off simultaneously for a preset second time period, control Q8 to turn on.

[0152] S433, control the first DC-DC module at the resonant frequency of the first DC-DC module and start the second DC-DC module to store the energy of the bus capacitor in the battery.

[0153] In this embodiment, the open-loop control of the first DC-DC module is performed through the resonant frequency, thereby not only improving the energy conversion efficiency but also streamlining the control, thus reducing the control complexity and control cost.

[0154] S434, determine whether the voltage value of the X-capacitor module exceeds the first preset threshold. When the voltage value of the X-capacitor module does not exceed the first preset threshold, the process ends. When the voltage value of the X-capacitor module exceeds the first preset threshold, execute S431.

[0155] In this embodiment, when three-phase charging is performed, the energy of the three X-capacitor modules is discharged simultaneously, which not only improves the discharge rate but also avoids the safety risk of still having contact with the charging port after a period of time after unplugging the gun.

[0156] Furthermore, it should be noted that during the charging process of the battery, the voltage or power of the battery is still continuously monitored. When the voltage of the battery reaches the second preset threshold, the energy of the X-capacitor module can be stored in the power battery.

[0157] In step S44, control the PFC module and the first DC-DC module to execute a preset three-phase discharge strategy to discharge the energy of the X-capacitor module back to the power battery.

[0158] Based on this embodiment, in other embodiments, refer to Figure 8 , this step S44 includes:

[0159] S441, continuously control the upper switching tubes of the three-phase bridge arm of the PFC module to turn off simultaneously, and control the lower switching tubes of the lower three-phase bridge arm of the PFC module to turn on simultaneously for a preset first time period to discharge and store the energy of the X-capacitor module in the inductor.

[0160] In this embodiment, refer to Figure 1 , a body diode is connected in parallel with Q7 and Q8 in the power frequency bridge arm. Therefore, in this embodiment, the current can be conducted through the body diode. It should be noted that when no body diode is connected in parallel with Q7 and Q8 of the power frequency bridge arm, then in step S441 of this embodiment, continuously control the upper switching tubes of the three-phase bridge arm of the PFC module to turn on simultaneously, and control the lower switching tubes of the lower three-phase bridge arm of the PFC module to turn off simultaneously for a preset first time period, and control Q8 to turn on at the same time.

[0161] S442. Continuously control the upper switching tubes of the three-phase bridge arms of the PFC module to conduct simultaneously, and control the lower switching tubes of the lower three-phase bridge arms of the PFC module to turn off simultaneously for a preset first time period to store the energy of the inductor into the bus capacitor.

[0162] In this embodiment, referring to Figure 1 , a body diode is connected in parallel with Q7 and Q8 in the power frequency bridge arm. Therefore, in this embodiment, the current can conduct through the body diode. It should be noted that when no body diode is connected in parallel with Q7 and Q8 of the power frequency bridge arm, then in step S442 of this embodiment, while continuously controlling the upper switching tubes of the three-phase bridge arms of the PFC module to conduct simultaneously and controlling the lower switching tubes of the lower three-phase bridge arms of the PFC module to turn off simultaneously for a preset first time period, control Q8 to conduct.

[0163] S443. Control the first DC-DC module at the resonant frequency of the first DC-DC module to store the energy of the bus capacitor into the power battery.

[0164] S444. Determine whether the voltage value of the X-capacitor module exceeds a first preset threshold. When the voltage value of the X-capacitor module does not exceed the first preset threshold, end. When the voltage value of the X-capacitor module exceeds the first preset threshold, execute S441.

[0165] In this embodiment, when the battery is fully charged, the energy flows back to the power battery, avoiding the energy of the X-capacitor module still flowing back to the battery, which may affect the battery and further shorten the service life of the battery.

[0166] This embodiment has the following beneficial effects:

[0167] (1) In different charging modes, the number of X-capacitor modules entering the working state is different. Therefore, the number of X-capacitor modules with voltage after unplugging the gun is also different. Thus, when charging ends, different discharge strategies are adopted according to different charging modes to ensure that the X-capacitor modules entering the working state are discharged synchronously, thereby improving the energy discharge rate of the capacitor. Furthermore, the energy of the X-capacitor modules at the charging port will be quickly discharged after unplugging the gun, reducing the risk of the energy of the X-capacitor module being output through the charging port and endangering personal safety.

[0168] (2) The X-capacitor modules at the charging port flow back to the power battery or the battery to realize energy recovery, thereby improving the effective utilization rate of energy.

[0169] (3) The charging mode is confirmed and recorded during charging connection. Therefore, when charging ends, the confirmed charging mode recorded can be directly retrieved, without the need to identify the charging mode again. Thus, both the discharge control strategy is streamlined and the discharge control rate is improved.

[0170] Referring toFigure 9 , based on this embodiment, in other embodiments, before step S1, it further includes:

[0171] S10. When a charging connection instruction is received, identify whether the external power supply is a single-phase power supply or a three-phase power supply, and start the single-phase charging mode and record it or start the three-phase charging mode and record it according to the identification result.

[0172] In this embodiment, when a gun plugging operation is detected, a charging connection instruction will be generated. Specifically, the national standard stipulates that there is an RC resistor on the charging gun, and this RC resistor is used to identify the RC resistance value of the charging gun. If the detected RC resistance value is infinite, it is considered that the charging gun is disconnected. If the detected RC resistance value is a constant, it is considered that the charging gun has been inserted into the charging port.

[0173] Based on this embodiment, in other embodiments, refer to Figure 10 , step S10 includes:

[0174] S100. Obtain the first phase and the first effective voltage value corresponding to the first phase bridge arm, the second phase and the second effective voltage value corresponding to the second phase bridge arm, and the third phase and the third effective voltage value corresponding to the third phase bridge arm.

[0175] S101. Obtain the first phase difference between the first phase and the second phase, the second phase difference between the second phase and the third phase, and the third phase difference between the third phase and the first phase.

[0176] S102. Judge whether the external power supply is a single-phase power supply or a three-phase power supply according to the first phase difference, the second phase difference, the third phase difference, the first effective voltage value, the second effective voltage value and the third effective voltage value; if it is determined that the external power supply is a single-phase power supply, execute step S103. If it is determined that the external power supply is a three-phase power supply, execute step S104.

[0177] S103. Then start the single-phase charging mode and record it;

[0178] S104. Then start the three-phase charging mode and record it.

[0179] In this embodiment, the judgment of the external power supply by the effective voltage value and the judgment of the external power supply by the phase difference have been described in detail in the above embodiments. Therefore, it will not be elaborated here.

[0180] Compared with the related art, when only the phase difference is used for identification, if the phase detection is abnormal, misjudgment will occur; or when only the effective voltage value is used for identification, if the obtained effective voltage value is interfered, misjudgment will be caused. Therefore, in this embodiment, the phase difference and the effective voltage value are combined to identify the single-phase charging / three-phase charging mode, so that when the phase difference or the effective voltage value cannot be accurately identified, another identification method is used for further identification, thereby improving the identification accuracy and reducing the misjudgment rate.

[0181] The electric vehicle of this embodiment will be described below.

[0182] The electric vehicle according to the embodiment of the present invention includes the on-vehicle charging system described in the above embodiment.

[0183] The on-vehicle charging system in this embodiment is the same as the on-vehicle charging system described in the above embodiment. Therefore, it will not be described in detail here.

[0184] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0185] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0186] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0187] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. An energy reflux and discharge method, characterized in that, It is applied to a vehicle-mounted charging device with multiple capacitor modules at the charging port. The vehicle-mounted charging device further includes: a PFC module, a first DC-DC module, and a second DC-DC module. The second end of the PFC module is connected to the first end of the first DC-DC module. The second end of the first DC-DC is respectively connected to the first end of the second DC-DC module and the power battery. The second end of the second DC-DC module is connected to the storage battery. There are at least three X-capacitor modules at the charging port. The PFC module includes three-phase bridge arms, and each phase bridge arm corresponds to an X-capacitor module; The energy reflux discharge method includes: When receiving an end charging instruction, obtain the confirmed charging mode identified during charging connection; Judge whether it is single-phase charging or three-phase charging according to the confirmed charging mode; When it is determined to be single-phase charging, control the vehicle-mounted charging device to execute a preset single-phase discharge strategy to discharge the energy of the multiple capacitor modules back to the power battery or the storage battery; When it is determined to be three-phase charging, control the vehicle-mounted charging device to execute a preset three-phase discharge strategy to discharge the energy of the multiple capacitor modules back to the power battery or the storage battery; Among them, the step of when it is determined to be three-phase charging, controlling the vehicle-mounted charging device to execute a preset three-phase discharge strategy to discharge the energy of the multiple capacitors back to the power battery or the storage battery includes: When the fourth voltage value across the storage battery does not exceed the second preset threshold, control the PFC module, the first DC-DC module, and the second DC-DC module to execute a preset three-phase discharge strategy to discharge the energy of the X-capacitor module back to the storage battery.

2. The energy return and discharge method according to claim 1, wherein The vehicle-mounted charging device further includes an EMI module. The first end of the EMI module is connected to an external power supply, and the second end of the EMI module is connected to the first end of the PFC module; The step of when it is determined to be single-phase charging, controlling the vehicle-mounted charging device to execute a preset single-phase discharge strategy to discharge the energy of the multiple capacitors back to the power battery or the storage battery includes: When it is determined to be single-phase charging, obtain the first voltage value corresponding to the X-capacitor module corresponding to the conducting phase bridge arm in the three-phase bridge arm; Judge whether the first voltage value exceeds the first preset threshold; When the first voltage value exceeds the first preset threshold, obtain the second voltage value across the storage battery; When the second voltage value does not exceed the second preset threshold, control the PFC module, the first DC-DC module, and the second DC-DC module to execute a preset single-phase discharge strategy to discharge the energy of the X-capacitor module back to the storage battery.

3. The energy return and discharge method according to claim 2, characterized in that, After the step of obtaining the second voltage value across the storage battery, it further includes: When the second voltage value exceeds the second preset threshold, control the PFC module and the first DC-DC module to execute a preset single-phase discharge strategy to discharge the energy of the X-capacitor module back to the power battery.

4. The energy return and discharge method according to claim 2, wherein When it is determined that three-phase charging is in progress, the step of controlling the on-vehicle charging device to execute a preset three-phase discharging strategy to discharge the energy of the plurality of capacitors back to the power battery or the storage battery further includes: When it is determined that three-phase charging is in progress, obtain the third voltage value of each X-capacitor module; Determine whether the third voltage values of the three X-capacitor modules all do not exceed the first preset threshold; When it is determined that at least one of the third voltage values of the three X-capacitor modules exceeds the first preset threshold, obtain the fourth voltage value across the storage battery.

5. The energy return and discharge method according to claim 4, characterized in that, The PFC module further includes three inductors and a bus capacitor, and each inductor is correspondingly connected to one phase arm; the step of controlling the PFC module, the first DC-DC module, and the second DC-DC module to execute a preset three-phase discharging strategy to discharge the energy of the X-capacitor module back to the storage battery includes: Continuously control the upper switching tubes of the three-phase arm of the PFC module to turn off simultaneously, and control the lower switching tubes of the lower three-phase arm of the PFC module to turn on simultaneously for a preset first time period to store the energy of the X-capacitor module in the inductor; Continuously control the upper switching tubes of the three-phase arm of the PFC module to turn on simultaneously, and control the lower switching tubes of the lower three-phase arm of the PFC module to turn off simultaneously for a preset second time period to store the energy of the inductor in the bus capacitor; Control the first DC-DC module at the resonant frequency of the first DC-DC module and start the second DC-DC module to store the energy of the bus capacitor in the storage battery, and repeat the above operations until the voltage value of the X-capacitor module does not exceed the first preset threshold.

6. The energy return and discharge method according to claim 4, wherein After the step of obtaining the fourth voltage value across the storage battery, it further includes: When the fourth voltage value exceeds the second preset threshold, control the PFC module and the first DC-DC module to execute a preset three-phase discharging strategy to discharge the energy of the X-capacitor module back to the power battery.

7. The energy reflux and discharge method according to claim 6, characterized in that The PFC module further includes three inductors and a bus capacitor, and each inductor is correspondingly connected to one phase arm; the step of controlling the PFC module and the first DC-DC module to execute a preset three-phase discharging strategy includes: Continuously control the upper switching tubes of the three-phase arm of the PFC module to turn off simultaneously, and control the lower switching tubes of the lower three-phase arm of the PFC module to turn on simultaneously for a preset first time period to discharge and store the energy of the X-capacitor module in the inductor; Continuously control the upper switching tubes of the three-phase arm of the PFC module to turn on simultaneously, and control the lower switching tubes of the lower three-phase arm of the PFC module to turn off simultaneously for a preset first time period to store the energy of the inductor in the bus capacitor; Control the first DC-DC module at the resonant frequency of the first DC-DC module to store the energy of the bus capacitor in the power battery, and repeat the above operations until the voltage value of the X-capacitor module does not exceed the first preset threshold.

8. The energy return and discharge method according to claim 2, characterized in that, Before the step of receiving the end charging instruction, it further includes: When a charging connection instruction is received, identify whether the external power supply is a single-phase power supply or a three-phase power supply, and start the single-phase charging mode and record it or start the three-phase charging mode and record it according to the identification result.

9. The energy return and discharge method according to claim 8, wherein The step of identifying whether the external power supply is a single-phase power supply or a three-phase power supply, and starting the single-phase charging mode and recording it or starting the three-phase charging mode and recording it according to the identification result includes: Obtain a first phase and a first effective voltage value corresponding to the first phase bridge arm, a second phase and a second effective voltage value corresponding to the second phase bridge arm, and a third phase and a third effective voltage value corresponding to the third phase bridge arm; Obtain a first phase difference between the first phase and the second phase, a second phase difference between the second phase and the third phase, and a third phase difference between the third phase and the first phase; Judge whether the external power supply is a single-phase power supply or a three-phase power supply according to the first phase difference, the second phase difference, the third phase difference, the first effective voltage value, the second effective voltage value and the third effective voltage value; If it is determined that the external power supply is a single-phase power supply, start the single-phase charging mode and record it; If it is determined that the external power supply is a three-phase power supply, start the three-phase charging mode and record it.

10. A vehicle-mounted charging system, characterized in that, It includes an in-vehicle charging device and a controller connected to the in-vehicle charging device, and the controller is used to control the in-vehicle charging device to execute the energy return discharge method according to any one of claims 1-9.

11. An electric vehicle, characterized in that, It includes the in-vehicle charging system according to claim 10.

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