Charging system based on motor winding multiplexing and control method

Abstract

The invention relates to the technical field of electric vehicle charging, in particular to a charging system based on motor winding multiplexing and a control method. Comprising a three-level active midpoint clamping inverter, a power battery pack is electrically connected to the direct current side of the three-level active midpoint clamping inverter, a motor winding is electrically connected to the three-phase output end of the alternating current side of the three-level active midpoint clamping inverter, and an AC / AC converter is electrically connected to the other side of the motor winding. The system further comprises a mode switching module which is arranged between the motor winding and the AC / AC converter and used for mode switching and enabling energy to flow in two directions, and the system integration degree is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle charging, and particularly to a charging system and control method based on motor winding reuse. Background Art

[0002] The electrical systems of existing electric mobile chassis generally adopt a charging-electric drive discrete architecture, which has multiple technical bottlenecks:

[0003] Topological redundancy of the charging system: The traditional solution adopts a two-stage energy conversion chain (AC→DC→DC) of "single-phase AC / DC rectifier + isolated DC / DC converter (OBC)". Although the charging function from the power grid to the battery can be achieved, as an independent module, the OBC needs to be additionally configured with components such as high-frequency transformers and filter inductors, resulting in a significant increase in the volume, weight and cost of the system. Moreover, discrete components such as the intermediate bus capacitor between the rectifier and the OBC further exacerbate the energy loss (the typical efficiency is lower than 92%).

[0004] Unidirectional energy transfer path: Existing OBCs generally only support charging from the power grid to the battery, and cannot achieve energy interconnection for peak shaving and valley filling of the power grid through "battery→power grid (V2G)", nor can they directly drive on-vehicle high-power equipment (such as construction machinery tools) through "battery→load (V2L)" under parking conditions. This unidirectional characteristic severely restricts the functional expansion of the electric chassis as a mobile energy storage unit.

[0005] Imbalance between the energy efficiency and cost of the discharge system: The two-level inverter topology is widely used at the motor drive end, and its power devices need to withstand the full DC bus voltage (the device withstand voltage under a 400V platform

[0006] ≥600V). This not only pushes up the selection cost of IGBT / SiC modules (accounting for 40%-50% of the total inverter cost), but also causes too high total harmonic distortion (THD) of the output voltage due to high dv / dt, leading to motor torque ripple and high-frequency electromagnetic interference, directly affecting the stability of the drive system.

[0007] Low utilization rate of hardware resources: The hardware resources of the charging and discharge systems are completely independent at the physical level. Core components such as motor windings and inverter power modules are idle in the charging mode, resulting in low space utilization rate and power density, and it is difficult to meet the urgent need for high integration of compact chassis.

[0008] With the development of electric mobile platforms towards "multi-functional integration (V2X) and high-voltage platforms (800V)", the traditional discrete architecture can no longer balance the following requirements: ① Compatibility between hardware simplification and function expansion; ② Game between the cost of high-voltage withstand devices and system energy efficiency; ③ Co-design of bidirectional power interaction ability and safety isolation. Summary of the Invention

[0009] The object of the present invention is to provide a charging system and a control method based on motor winding reuse. The systematic defects of the prior art indicate that realizing the hardware reuse of multiple scenarios of charging-discharging-power consumption through topology reconstruction has become the key path to break through the industry bottleneck, and the present invention is an innovative solution proposed based on this technical logic.

[0010] The above object of the present invention is achieved by the following technical solutions: A charging system based on motor winding reuse, including a three-level active neutral point clamped inverter, a power battery pack electrically connected to the DC side of the three-level active neutral point clamped inverter, a motor winding electrically connected to the three-phase output terminals of the AC side of the three-level active neutral point clamped inverter, an AC / AC converter electrically connected to the other side of the motor winding, and further including a mode switching module disposed between the motor winding and the AC / AC converter for mode switching and enabling bidirectional energy flow.

[0011] As a preference of the present invention, the mode switching module includes a contactor K1 and a contactor K2. The contactor K2 is connected to one phase branch of the motor winding and this phase branch is electrically connected to the output terminal of the AC / AC converter, and the contactor K1 is connected between this phase branch and the output terminal of the AC / AC converter.

[0012] As a preference of the present invention, the AC / AC converter is an isolation type converter, specifically including a power factor correction module, an isolation transformer module, an inverter module, and an LC output filter.

[0013] As a preference of the present invention, the inverter module is an H full-bridge inverter module.

[0014] As a preference of the present invention, the charging system further includes a controller, and the controller is used to control the switching actions of the three-level active neutral point clamped inverter, the AC / AC converter, and the mode switching module.

[0015] As a preference of the present invention, the three-level active neutral point clamped inverter has 18 SiC-MOSFETs, and each phase has 6 SiC-MOSFETs.

[0016] As a preference of the present invention, each single-phase bridge arm in each phase of the three-level active neutral point clamped inverter has 4 switching SiC-MOSFETs and 2 clamping SiC-MOSFETs.

[0017] A control method for a charging system based on motor winding reuse. In the grid charging mode, disconnect the contactor K2 and close the contactor K1 to convert grid AC into DC to charge the battery. In the parking power supply mode, disconnect the contactor K2 and close the contactor K1 to invert the battery DC into AC and adjust it to 220V AC output. In the electric drive mode, disconnect the contactor K1 and close the contactor K2, and dynamically adjust the modulation ratio of the three-level active neutral point clamped inverter according to the motor speed / torque command for driving.

[0018] As a preference of the present invention, in the grid charging mode and the parking power supply mode, first disconnect K2 and close K1, start the AC / AC converter after a delay of 50ms, and then start the three-level active neutral point clamped inverter after a further delay of 50ms. In the electric drive mode, first disconnect K1 and close K2, and start the three-level active neutral point clamped inverter after a delay of 50ms. In all modes, detect the SiC-MOSFET junction temperature, and trigger temperature protection when the junction temperature > 125°C.

[0019] As a preference of the present invention, the motor winding constitutes a filter inductor in the grid charging mode.

[0020] The beneficial effects of the present invention:

[0021] 1. The system integration degree is significantly improved:

[0022] Hardware simplification: By canceling the independent on-board charger (OBC) and reusing the motor winding as a filter inductor, the number of system components is significantly reduced;

[0023] Cost optimization: Omitting high-cost components such as the OBC dedicated high-frequency transformer and filter inductor reduces the system manufacturing cost.

[0024] 2. The power quality and drive performance are optimized:

[0025] Harmonic suppression:

[0026] In the charging mode, the grid-side current THD < 3%;

[0027] In the power supply mode, the output voltage THD < 2%.

[0028] Torque smoothing: The harmonic content of the ANPC three-level output waveform is reduced to 1 / 3 of the traditional two-level, and the motor torque ripple rate is significantly optimized, reducing vibration and noise.

[0029] 3. The function expandability and compatibility are enhanced:

[0030] Full-scenario coverage:

[0031] Support for V2G (vehicle-to-grid): Realize two-way energy flow, and the maximum feedback power reaches 7kW;

[0032] Support for V2L (Vehicle-to-Load): Output 220V AC (regulated voltage within ±2%), capable of driving high-power tools above 6kW.

[0033] Voltage self-adaptation: Through duty cycle adjustment, it is compatible with a wide range of battery voltages, meeting the upgrade requirements of future high- and low-voltage platforms.

[0034] 4. Upgrade in safety and reliability

[0035] Electrical isolation guarantee: The AC / AC converter is equipped with a high-frequency transformer inside to achieve electrical isolation between the primary and secondary sides.

[0036] Thermal failure protection: The junction temperature monitoring accuracy of SiC-MOSFET is ±5°C.

[0037] 5. Mode interlock:

[0038] Fast response: The mode switching time < 5ms, enabling seamless transition between charge and discharge states;

[0039] Intelligent adaptation: Automatically identify the connection of the power grid / load, eliminating the need for manual mode switching. Description of the drawings

[0040] Figure 1 It is the circuit diagram of the charging system in Embodiment 1;

[0041] Figure 2 For Figure 1 The circuit diagram of the left part;

[0042] Figure 3 For Figure 1 The circuit diagram of the right part. Detailed implementation

[0043] The following further elaborates on the present invention in conjunction with the attached drawings.

[0044] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

[0045] Embodiment 1, as Figures 1-3 shown, a charging system based on motor winding reuse includes a three-level active neutral point clamped inverter, a power battery pack electrically connected to the DC side of the three-level active neutral point clamped inverter, a motor winding electrically connected to the three-phase output terminals of the AC side of the three-level active neutral point clamped inverter, an AC / AC converter electrically connected to the other side of the motor winding, and a mode switching module disposed between the motor winding and the AC / AC converter for mode switching and enabling bidirectional energy flow.

[0046] The solution feature of this application lies in the reuse of the motor winding, which not only functions under driving, but can also be effectively utilized during charging and power supply. By combining a three-level active neutral point clamped inverter, an AC / AC converter, and a newly designed mode switching module, bidirectional energy flow can be directly achieved based on the motor winding. The three-level active neutral point clamped inverter in this application uses an ANPC (Active Neutral Point Clamped) type inverter. Compared with the NPC (Neutral Point Clamped) inverter, the diodes in the NPC are replaced with active switches (such as IGBTs or MOSFETs). By dynamically controlling the neutral point voltage, the problem of the bus capacitor voltage balance in the NPC is solved, and the voltage balance is improved. Although the number of switching devices is more, due to the introduction of active switches, the loss distribution becomes more uniform, making thermal management easier and improving the reliability and efficiency of the system. It is further optimized based on the NPC and is suitable for applications with higher requirements for efficiency and power density, such as high-power inverters and motor drives, but the control difficulty is greater.

[0047] Specifically, the mode switching module includes contactor K1 and contactor K2. Contactor K2 is connected to one phase branch of the motor winding, and this phase branch is electrically connected to the output terminal of the AC / AC converter. And contactor K1 is connected between this phase branch and the output terminal of the AC / AC converter. For example, contactor K1 and contactor K2 are arranged on the branch side of the A phase of the permanent magnet synchronous motor, and it is on the branch side outside the winding, that is, on the branch on the other side of the motor M away from the center point of the winding. Contactor K2 is connected in series to the A-phase branch, and contactor K1 is connected in series between the point on the A-phase branch and the single-phase AC output port (AC_OUT).

[0048] Preferably, the AC / AC converter is an isolation type converter, specifically including a power factor correction module, an isolation transformer module, an inverter module, and an LC output filter.

[0049] Among them, the inverter module can select an H-full bridge inverter module. The power factor correction module can select a totem pole PFC power factor correction module. The isolation transformer module can use an isolation high-frequency transformer.

[0050] The charging system also includes a controller, which is used to control the switching actions of the three-level active neutral point clamped inverter, the AC / AC converter, and the mode switching module. That is, to control the active switches of the three-level active neutral point clamped inverter and the AC / AC converter, and to control the on / off of contactor K1 and contactor K2.

[0051] Further, the three-level active neutral-point clamped inverter has 18 SiC-MOSFETs, and each phase has 6 SiC-MOSFETs. SiC-MOSFET is silicon carbide metal-oxide-semiconductor field-effect transistor.

[0052] Among them, each single-phase bridge arm in each phase of the three-level active neutral-point clamped inverter has 4 switching SiC-MOSFETs and 2 clamping SiC-MOSFETs.

[0053] According to the foregoing inventive concept solution, some specific implementation cases are given below:

[0054] The framework and execution steps of the overall system are roughly divided into four aspects:

[0055] S1. System topology construction

[0056] S11. Deploy a three-level active neutral-point clamped (ANPC) inverter on the electric mobile chassis, directly connect the DC output terminals (P_bat / N_bat) of the power battery pack to the positive and negative poles (P / N) of the DC bus of the three-level active neutral-point clamped (ANPC) inverter, and cancel the bidirectional DC / DC conversion link in the traditional solution; the three-phase output terminals (U / V / W) on the AC side are respectively connected to the three-phase A\B\C windings of the motor;

[0057] S12. Connect two support capacitors C1 / C2 in series between the positive and negative poles (P / N) of the ANPC inverter DC bus, and, for example, connect the midpoint O to the midpoint of each phase switch group (S5, S6) to achieve clamping;

[0058] S13. Lead out output terminals (A / B / C) from the three-phase windings of the motor, and set contactors K1 and K2 on the side of one of the phase branches. Connect the circuit in the driving mode; cut off the loop in the charging mode and connect it to the single-phase AC output port (AC_OUT) to form a filtering loop in the charging mode;

[0059] S14. The single-phase rectifier filtering module consists of: (1) a totem-pole PFC power factor correction module, (2) a CLLC-type isolated high-frequency transformer circuit module, (3) an H full-bridge inverter module, and (4) an LC output filter.

[0060] S15. Configure a control board based on a digital signal processor (DSP), and its PWM output terminals are respectively connected to the driving circuits of 18 SiC-MOSFETs (S1-S18) of the three-level active neutral-point clamped (ANPC) inverter and the AC / AC converter switch.

[0061] S2. Mode switching logic

[0062] S21. When it is detected that the single-phase AC input port is connected to the power grid, enter the grid charging mode:

[0063] ● Disconnect the contactor K2 and connect the contactor K1 to connect the single-phase AC output port in series to the main circuit;

[0064] ● At this time, the motor winding is reconfigured as a charging filter inductor, and the equivalent inductance value of the motor winding is determined by the motor itself, such as 3 mH, 4 mH, etc.

[0065] ● Activate the carrier modulation (SPWM) of S1 - S18 to charge the power battery.

[0066] S22. When the chassis needs to drive the motor to run, enter the electric drive mode:

[0067] ● Connect the contactor K2 and disconnect the contactor K1. At this time, the single-phase AC output terminal is cut off;

[0068] ● Activate the carrier modulation (SPWM) of S1 - S18;

[0069] ● Dynamically adjust the modulation ratio according to the motor speed / torque command.

[0070] S23. Under the parking condition, when it is detected that the single-phase AC output port AC_OUT is connected to a load, enter the AC power supply mode:

[0071] ● Disconnect the contactor K2 and connect the contactor K1 to connect the single-phase AC output port in series to the main circuit;

[0072] ● At this time, the motor winding is reconfigured as a charging filter inductor, and the equivalent inductance value of the motor winding is determined by the motor itself, such as 3 mH, 4 mH, etc.;

[0073] ● Activate the carrier modulation (SPWM) of S1 - S18, and the power battery supplies power to the AC output terminal.

[0074] S3. Implement the bidirectional energy control strategy

[0075] S31. Energy control in the charging mode:

[0076] S311. Collect the grid voltage phase through the AC side voltage sensor and perform double-loop PI regulation with the DC side voltage given value. That is, in the charging system, there is a voltage sensor that can collect the grid

[0077] voltage phase;

[0078] S312. Generate the switching signal of the AC / AC converter to make the grid current track the sine reference

[0079] waveform (THD < 5%), and the total harmonic distortion is < 5%;

[0080] S313. Generate the switching signals of S1 - S18, and dynamically adjust the modulation ratio according to the actual battery voltage;

[0081] S314. Through the ANPC neutral - point potential balance algorithm, adjust the charging and discharging time of C1 / C2 in real - time, and control the bus voltage fluctuation within ±2%.

[0082] S32. Inverter control in the parking power - supply mode:

[0083] S321. Adopt the carrier - based PWM technology, dynamically adjust the modulation ratio according to the motor speed / torque command,

[0084] and generate the switching signals of S1 - S18;

[0085] S322. Introduce third - harmonic injection to improve the voltage utilization rate;

[0086] S323. Modify the modulation wave through the neutral - point voltage injection method to maintain the voltage balance of the bus capacitor.

[0087] S4. Realize the coordination of hardware reuse and safety protection

[0088] S41. Hardware reuse mechanism:

[0089] In the charging mode and the parking power - supply mode, use the A - phase winding of the motor as the filter inductor,

[0090] and connect it in series with the output terminal of the single - phase AC / AC converter.

[0091] S42. Multi - mode safety interlock:

[0092] S421. During the mode - switching transition period (<100μs), forcibly insert the dead - time and strictly start each functional module according to the power - on timing sequence;

[0093] S422. Real - time monitor the junction temperature of the SiC - MOSFET silicon carbide module and the temperature rise of the motor winding.

[0094] When the temperature exceeds 125°C, trigger the safety strategy;

[0095] S423. Configure redundant current sensors to cross - verify the charging and discharging current, and immediately cut off the power path when a deviation of more than 5% is detected.

[0096] S423. Configure redundant current sensors to cross - verify the charging and discharging current, and immediately cut off the power path when a deviation of more than 5% is detected.

[0097] Through the above - mentioned topological structure innovation, the following core technical means are formed:

[0098] Motor winding reuse mechanism: Reconstruct the three-phase windings of the motor into a charging filter inductor to achieve cross-scenario reuse of hardware resources; cancel the traditional OBC; Three-level ANPC and direct connection topology of the charging port: Selectively switch the power circuit through contactors; Form an overall new architecture of "battery-inverter-isolated AC / AC-grid".

[0099] The innovation of the control strategy lies in voltage adaptive control: In the grid charging mode, by adjusting the duty cycles of the AC / AC converter and the three-level ANPC, directly match the battery voltage and the grid voltage to achieve charging of power batteries with any voltage level.

[0100] Bidirectional power control: In the parking power supply mode, through the three-level ANPC and the AC / AC converter, invert the high voltage of the battery into 220V AC to meet the usage requirements of multiple scenarios.

[0101] Seamless mode switching technology: The control strategy algorithm based on the finite state machine (FSM) ensures smooth switching among the charging, power supply, and electric drive modes, that is, better control of the contactor states.

[0102] The control strategy algorithm module of the finite state machine (FSM) and the control board based on the digital signal processor (DSP) both belong to a part of the controller to control the actions of the corresponding modules.

[0103] In addition, this application also has a collaborative design of safety and efficiency: There is a strict power-on sequence on the AC and DC sides to ensure the orderly and safe operation of each functional module. Real-time monitor the junction temperature of the SiC-MOSFET silicon carbide module and the temperature rise of the motor windings, and trigger the high-temperature derating / shutdown strategy.

[0104] The key modules and connection relationships of the entire system are as follows:

[0105] Three-level active neutral point clamped (ANPC) inverter, its DC side is directly connected to the power battery pack, and the three-phase output terminals on the AC side are connected to the motor windings;

[0106] Contactor group (K1-K2): Used to switch the power paths of the charging, power supply, and electric drive modes:

[0107] K1: Used to connect the AC output port of the grid-side AC / AC converter;

[0108] K2: Used to connect the motor windings.

[0109] Isolated AC / AC converter, including a high-frequency transformer, a totem-pole PFC power factor correction module based on SiC-MOSFET, and an H-bridge full-bridge inverter module, and also includes an LC output filter;

[0110] A controller, configured to control a three-level (ANPC) inverter, an AC / AC converter, and a contactor group to achieve mode switching and bidirectional energy flow.

[0111] In the specific circuit structure, the three-level active neutral point clamped (ANPC) inverter has 18 SiC-MOSFETs (S1 - S18), which are divided into three groups of parallel three-phase branches, with 6 SiC-MOSFETs in each group. In each phase, there are 4 series-connected switch SiC-MOSFETs on the main bridge arm. Then, 2 clamping SiC-MOSFETs are connected in parallel to the middle two SiC-MOSFETs on the main bridge arm. As shown in the circuit diagram, on phase A, S1, S2, S3, and S4 are connected in series, S5 and S6 are connected in parallel with S2 and S3, the point between S5 and S6 is connected to the midpoint O of the support capacitors C1 / C2 to achieve clamping, and the point between S2 and S3 is connected to the motor phase A branch. The other phases can be connected with reference to phase A.

[0112] The H full-bridge inverter module is also preferably based on SiC-MOSFETs, including four parallel bridge arms. Each bridge arm has 2 series-connected SiC-MOSFETs, and there is also a voltage stabilizing capacitor connected in parallel between the left and right bridge arms. Among them, the left two bridge arms are connected to an LC output filter, and the point between the capacitor and the inductor of this filter is used as the single-phase AC output port AC_OUT, and the other side of the capacitor is used as the return neutral port N. However, in the AC / AC converter of this application, the return output port is not grounded, and the return neutral port N is electrically connected to the point between the contactor K2 and the motor phase A winding. The single-phase AC output port AC_OUT is connected in series with the contactor K1, and the contactor K2 is connected in series to the phase A branch, while the contactor K1 is connected in series between the point on the phase A branch and the single-phase AC output port (AC_OUT). The right two bridge arms are also connected to an LC output filter and are connected to one side of the high-frequency transformer. The power factor correction module is also preferably based on SiC-MOSFETs, including four parallel bridge arms, and there is also a voltage stabilizing capacitor connected in parallel between the left and right bridge arms. The difference is that each of the left two bridge arms has 2 series-connected SiC-MOSFETs, one of the right two bridge arms has 2 series-connected IGBTs, and one has 2 series-connected SiC-MOSFETs. And the left two bridge arms are connected to an LC output filter and are connected to the other side of the high-frequency transformer, while the right two bridge arms are connected to the grid through an inductive filter circuit. LC filters are connected to both sides of the high-frequency transformer to form a CLLC-type isolated high-frequency transformer module.

[0113] Through the design of the above-mentioned various circuit modules, the entire new charging system is formed. The system integration degree is significantly improved, and it has the various advantages mentioned above.

[0114] Embodiment 2, a control method for a charging system based on motor winding reuse. This method is based on the charging system of Embodiment 1 and specifically includes: in the grid charging mode, disconnect contactor K2 and close contactor K1 to convert grid AC into DC to charge the battery; in the parking power supply mode, disconnect contactor K2 and close contactor K1 to invert the battery DC into AC and adjust it to 220V AC output;

[0115] In the electric drive mode, disconnect contactor K1 and close contactor K2, and dynamically adjust the modulation ratio of the three-level active neutral point clamped inverter according to the motor speed / torque command for driving. The specific driving steps are implemented as follows:

[0116] 1. Understand the basic concepts

[0117] Modulation Index: The modulation index refers to the ratio of the inverter output voltage to the DC bus voltage. It directly affects the amplitude of the inverter output voltage.

[0118] Speed and torque commands: The motor control system usually uses speed and torque commands to adjust the operating state of the motor.

[0119] 2. Establish a control model

[0120] Determine the motor operating state: According to the motor speed and torque commands, it is first necessary to determine the current operating state of the motor through a control algorithm (such as PID control, fuzzy control, etc.).

[0121] Calculate the required output voltage: Calculate the required output voltage according to the load characteristics and speed / torque requirements of the motor.

[0122] 3. Dynamically adjust the modulation ratio

[0123] Adjust the modulation ratio according to the voltage demand: Use the following formula to calculate the modulation ratio:

[0124] Modulation Index(M)=V out / (V DC / 2), where V out is the required output voltage and V DC is the DC bus voltage.

[0125] Adjust the modulation ratio: Dynamically adjust the modulation ratio according to the real-time speed and torque feedback to ensure that the output voltage meets the operating requirements of the motor.

[0126] 4. Implement the control strategy

[0127] PWM Control: In a three-level active neutral point clamped inverter, pulse width modulation (PWM) technology is typically used to generate the required output voltage waveform. The duty cycle of the PWM is adjusted according to the calculated modulation ratio.

[0128] Real-time Monitoring: Sensors are used to monitor the motor speed and torque in real time to ensure that the control system can respond quickly to changes.

[0129] 5. Considered Factors

[0130] Overload and Protection Mechanism: When adjusting the modulation ratio, overload conditions and protection mechanisms need to be considered to avoid damage to the inverter and the motor.

[0131] Thermal Management: Operating at a high modulation ratio may cause the inverter to heat up, and an effective heat dissipation scheme needs to be designed.

[0132] Filtering and Harmonic Control: Although a three-level inverter can reduce harmonics, filters still need to be designed to further reduce the harmonic impact.

[0133] 6. Implementation and Verification

[0134] Simulation Test: Before actual application, tests are carried out through simulation software to verify the effectiveness of the control algorithm and modulation ratio adjustment.

[0135] Field Test: Field tests are carried out on an experimental platform, and parameters are adjusted to ensure the stability and efficiency of the system under various operating conditions.

[0136] Through the above steps, the modulation ratio of the three-level active neutral point clamped inverter can be effectively adjusted dynamically according to the motor speed and torque commands, thereby achieving efficient driving of the motor.

[0137] Furthermore, in the grid charging mode and the parking power supply mode, first disconnect K2, close K1, start the AC / AC converter after a 50 ms delay, and then start the three-level active neutral point clamped inverter after another 50 ms delay; in the electric drive mode, first disconnect K1, close K2, and start the three-level active neutral point clamped inverter after a 50 ms delay; in all modes, detect the SiC-MOSFET junction temperature, and when the junction temperature > 125 °C, trigger temperature protection.

[0138] The motor winding forms a charging filter inductor in the grid charging mode, and the equivalent inductance value of the motor winding is determined by the motor itself, such as 3 mH, 4 mH, etc.

[0139] Specific Implementation Case:

[0140] In the grid charging mode:

[0141] Disconnect K2, close K1, convert AC to DC for charging the battery directly through the AC / AC converter and power factor correction, and then through the ANPC converter;

[0142] Adjust the duty cycle of the ANPC inverter to adaptively match the battery voltage to the equivalent grid-side voltage;

[0143] In the parking power supply mode:

[0144] Disconnect K2, close K1, invert the DC of the battery to AC through the ANPC inverter, adjust it to 220V AC output through the AC / AC converter and power factor correction;

[0145] In the electric drive mode:

[0146] Disconnect K1, close K2, and dynamically adjust the ANPC modulation ratio according to the motor speed / torque command.

[0147] Mode switching logic:

[0148] Based on the FSM state machine, detect the port connection status (grid / load access signal), and complete the coordinated switching of the contactor group and power devices within 5ms.

[0149] In the charging mode, the motor winding forms a filter inductor with an equivalent inductance value of 3mH.

[0150] The safety protection strategy includes:

[0151] Power-on timing control:

[0152] In the grid-connected mode, first disconnect K2, close K1, start the AC / AC converter after a 50ms delay, and then start the ANPC converter after a further 50ms delay;

[0153] In the electric drive mode, first disconnect K1, close K2, and start the ANPC converter after a 50ms delay.

[0154] Thermal management strategy:

[0155] Detect the junction temperature (T_j) of the SiC-MOSFET, and when T_j > 125°C, trigger temperature protection (50% power → shutdown).

[0156] Voltage adaptive algorithm: Establish a grid voltage - battery voltage mapping table, and quickly adjust the duty cycles of the AC / AC converter and ANPC through feed-forward compensation, with a response time < 1ms;

[0157] Efficiency optimization: Dynamically adjust the ANPC dead time according to the load rate and optimize the switching combination to reduce switching losses.

[0158] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A charging system based on motor winding reuse, characterized in that It includes a three-level active neutral-point clamped inverter, a power battery pack electrically connected to the DC side of the three-level active neutral-point clamped inverter, a motor winding electrically connected to the three-phase output terminals of the AC side of the three-level active neutral-point clamped inverter, an AC / AC converter electrically connected to the other side of the motor winding, and a mode switching module arranged between the motor winding and the AC / AC converter for mode switching and enabling bidirectional energy flow.

2. The charging system based on motor winding reuse according to claim 1, wherein, The mode switching module includes contactors K1 and K2. The contactor K2 is connected to one phase branch of the motor winding, and this phase branch is electrically connected to the output terminal of the AC / AC converter, and the contactor K1 is connected between this phase branch and the output terminal of the AC / AC converter.

3. The charging system based on motor winding reuse according to claim 2, wherein The AC / AC converter is an isolation transformer, specifically including a power factor correction module, an isolation transformer module, an inverter module, and an LC output filter.

4. The charging system based on motor winding reuse according to claim 3, characterized in that The inverter module is an H full-bridge inverter module.

5. The charging system based on motor winding reuse according to claim 3, characterized in that, The charging system further includes a controller for controlling the switching actions of the three-level active neutral-point clamped inverter, the AC / AC converter, and the mode switching module.

6. The charging system based on motor winding reuse according to claim 1, characterized in that, The three-level active neutral-point clamped inverter has 18 SiC-MOSFETs, and each phase has 6 SiC-MOSFETs.

7. A charging system based on motor winding reuse according to claim 6, characterized in that, Each single-phase bridge arm in each phase of the three-level active neutral-point clamped inverter has 4 switching SiC-MOSFETs and 2 clamping SiC-MOSFETs.

8. The control method of a charging system based on motor winding reuse according to claim 2, wherein, In the grid charging mode, disconnect the contactor K2 and close the contactor K1 to convert grid AC into DC to charge the battery; in the parking power supply mode, disconnect the contactor K2 and close the contactor K1 to invert the battery DC into AC and adjust it to 220VAC output; in the electric drive mode, disconnect the contactor K1 and close the contactor K2, and dynamically adjust the modulation ratio of the three-level active neutral-point clamped inverter according to the motor speed / torque command for driving.

9. The control method of a charging system based on motor winding multiplexing according to claim 8, characterized in that, In the grid charging mode and the parking power supply mode, first disconnect K2 and close K1, start the AC / AC converter after a delay of 50 ms, and then start the three-level active neutral-point clamped inverter after a further delay of 50 ms; In the electric drive mode, first disconnect K1 and close K2, and start the three-level active neutral-point clamped inverter after a delay of 50 ms; in all modes, detect the junction temperature of the SiC-MOSFET, and when the junction temperature > 125°C, trigger temperature protection.

10. The control method of a charging system based on motor winding multiplexing according to claim 8, characterized in that, The motor winding constitutes a filter inductor in the grid charging mode.

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