Charging system based on motor winding multiplexing

Abstract

The utility model relates to the technical field of electric vehicle charging, in particular to a charging system based on motor winding multiplexing. 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] This utility model relates to the field of electric vehicle charging technology, and in particular to a charging system based on motor winding reuse. Background Technology

[0002] The electrical systems of existing electric mobile chassis generally adopt a separate charging-electric drive architecture, which presents multiple technical constraints:

[0003] Charging system topology redundancy: Traditional solutions employ a two-stage energy conversion chain (AC→DC→DC) consisting of a single-phase AC / DC rectifier and an isolated DC / DC converter (OBC). While this enables grid-to-battery charging, the OBC, as an independent module, requires additional components such as a high-frequency transformer and filter inductor, significantly increasing system size, weight, and cost. Furthermore, discrete components like the intermediate bus capacitor between the rectifier and OBC further exacerbate energy losses (typically below 92% efficiency).

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

[0005] The energy efficiency and cost imbalance of the discharge system: the motor drive end widely adopts a two-level inverter topology, and its power devices need to withstand the entire DC bus voltage (device withstand voltage at a 400V platform).

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

[0007] Low utilization of hardware resources: The hardware resources of the charging and discharging system 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 and power density, which makes it difficult to meet the urgent need for high integration in compact chassis.

[0008] As electric mobility platforms evolve towards "multi-functional integration (V2X) and high-voltage platforms (800V)," traditional discrete architectures can no longer balance the following requirements: ① compatibility between hardware simplification and functional expansion; ② the trade-off between the cost of high-voltage components and system energy efficiency; ③ the collaborative design of bidirectional power interaction capability and safety isolation. Utility Model Content

[0009] The purpose of this invention is to provide a charging system based on motor winding reuse. The systemic deficiencies of existing technologies indicate that achieving hardware reuse across multiple scenarios (charging, discharging, and power consumption) through topology reconfiguration has become a key path to overcome industry bottlenecks, and this invention is an innovative solution proposed based on this technological logic.

[0010] The above-mentioned objective of this utility model is achieved through the following technical solution: a charging system based on motor winding reuse, comprising a three-level active neutral clamp inverter, a power battery pack electrically connected to the DC side of the three-level active neutral clamp inverter, a motor winding electrically connected to the three-phase output terminal of the AC side of the three-level active neutral clamp inverter, an AC / AC converter electrically connected to the other side of the motor winding, and further comprising 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 preferred embodiment of the present invention, the mode switching module includes contactor K1 and contactor K2. Contactor K2 is connected to one phase branch of the motor winding and the phase branch is electrically connected to the output terminal of the AC / AC converter. Contactor K1 is connected between the phase branch and the output terminal of the AC / AC converter.

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

[0013] As a preferred embodiment of this invention, the inverter module is an H-bridge inverter module.

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

[0015] As a preferred embodiment of this invention, the three-level active neutral clamp inverter has 18 SiC-MOSFETs, and each phase has 6 SiC-MOSFETs.

[0016] As a preferred embodiment of this invention, each phase of the three-level active neutral point clamping inverter has four switching SiC-MOSFETs and two clamping SiC-MOSFETs on a single-phase bridge arm.

[0017] As a preferred embodiment of this invention, contactor K2 is connected in series in the A-phase branch of the motor, while contactor K1 is connected in series between the point on the A-phase branch and the single-phase AC output port AC_OUT.

[0018] As a preferred embodiment of this invention, the neutral port N of the AC / AC converter is electrically connected to the point between the contactor K2 and the A-phase winding of the motor.

[0019] As a preferred embodiment of this invention, the motor winding is configured as a filter inductor in the grid charging mode.

[0020] The beneficial effects of this utility model are:

[0021] 1. Significantly improved system integration:

[0022] Hardware simplification: By eliminating the separate on-board charger (OBC) and reusing the motor windings as filter inductors, the number of system components is significantly reduced;

[0023] Cost optimization: By eliminating high-priced components such as the OBC-specific high-frequency transformer and filter inductor, the system manufacturing cost is reduced.

[0024] 2. Power quality and drive performance optimization:

[0025] Harmonic suppression:

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

[0027] In power supply mode, the output voltage THD is less than 2%.

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

[0029] 3. Enhanced functionality and compatibility:

[0030] Full-scene coverage:

[0031] Supports V2G (vehicle-to-grid): enables bidirectional energy flow with a maximum feedback power of 7kW;

[0032] Supports V2L (vehicle-to-load): Outputs 220V AC (±2% regulated), capable of driving high-power tools above 6kW.

[0033] Voltage Adaptive: By adjusting the duty cycle, it is compatible with an ultra-wide range of battery voltages and adapts to future upgrade requirements of high and low voltage platforms.

[0034] 4. Enhanced security and reliability

[0035] Electrical isolation protection: The AC / AC converter has a built-in high-frequency transformer to achieve electrical isolation between the primary and secondary sides.

[0036] Thermal failure protection: SiC-MOSFET junction temperature monitoring accuracy ±5℃.

[0037] 5. Mode interlock:

[0038] Fast response: Mode switching time <5ms, achieving seamless transition between charging and discharging states;

[0039] Intelligent adaptation: Automatically identifies grid / load access without requiring manual mode switching. Attached Figure Description

[0040] Figure 1 This is a circuit diagram of the charging system in Example 1;

[0041] Figure 2 for Figure 1 The circuit diagram on the left side;

[0042] Figure 3 for Figure 1 The circuit diagram on the right. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the accompanying drawings.

[0044] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of the present utility model.

[0045] Example 1, such as Figure 1-3 As shown, a charging system based on motor winding reuse includes a three-level active neutral clamp inverter, a power battery pack electrically connected to the DC side of the three-level active neutral clamp inverter, a motor winding electrically connected to the three-phase output terminal of the AC side of the three-level active neutral clamp 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 key feature of this application lies in the reuse of motor windings. These windings are effective not only for driving but also for charging and power supply. Combined with a three-level active neutral point clamp inverter, an AC / AC converter, and a newly designed mode switching module, bidirectional energy flow can be achieved directly from the motor windings. The three-level active neutral point clamp inverter in this application uses an ANPC (Active Neutral Point Clamped) inverter. Compared to 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 bus capacitor voltage balance problem of the NPC is solved, improving voltage balance. Although the number of switching devices is greater, the introduction of active switches results in a more uniform loss distribution, easier thermal management, and improved system reliability and efficiency. This further optimizes the NPC design, making it suitable for applications with higher efficiency and power density requirements, such as high-power inverters and motor drives, but it also presents greater control challenges.

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

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

[0049] The inverter module can be an H-bridge inverter module. The power factor correction module can be a totem-pole PFC power factor correction module. The isolation transformer module can be an isolation high-frequency transformer.

[0050] The charging system also includes a controller, which controls the switching actions of the three-level active midpoint clamp inverter, the AC / AC converter, and the mode switching module. Specifically, it controls the active switches of the three-level active midpoint clamp inverter and the AC / AC converter, and controls the on / off states of contactors K1 and K2.

[0051] Furthermore, the three-level active neutral clamp inverter has 18 SiC-MOSFETs, with 6 SiC-MOSFETs in each phase. SiC-MOSFETs are silicon carbide metal-oxide-semiconductor field-effect transistors.

[0052] The three-level active neutral clamp inverter has four switching SiC-MOSFETs and two clamping SiC-MOSFETs on each single-phase bridge arm of each phase.

[0053] Based on the aforementioned utility model concept, some specific implementation examples are given below:

[0054] The overall system architecture and execution steps can be roughly divided into four aspects:

[0055] S1, System Topology Construction

[0056] S11. Deploy a three-level active neutral point clamp (ANPC) inverter on the electric mobile chassis, and directly connect the DC output terminals (P_bat / N_bat) of the power battery pack to the positive and negative terminals (P / N) of the DC bus of the three-level active neutral point clamp (ANPC) inverter, eliminating the bidirectional DC / DC conversion stage in the traditional scheme; 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 supporting capacitors C1 / C2 in series between the positive and negative terminals (P / N) of the DC bus of the ANPC inverter, and, for example, connect point O to the midpoint of each phase switch group (S5, S6) to achieve clamping.

[0058] S13. Output terminals (A / B / C) are led out from the three-phase windings of the motor, and contactors K1 and K2 are installed on one of the phase branches. The circuit is connected in drive mode; the circuit is disconnected in charging mode and connected to the single-phase AC output port (AC_OUT) to form a filter circuit in charging mode.

[0059] S14. The single-phase rectifier and filter module consists of: (1) a totem pole PFC power factor correction module, (2) a CLLC type isolation 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), whose PWM output terminal is connected to the drive circuit of the 18 SiC-MOSFETs (S1-S18) of the three-level active neutral point clamp (ANPC) inverter and the AC / AC converter switch.

[0061] S2, Mode Switching Logic

[0062] S21. When a single-phase AC input port is detected to be connected to the power grid, the grid charging mode is entered:

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

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

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

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

[0067] ● When contactor K2 is turned on and contactor K1 is turned off, the single-phase AC output terminal is cut off.

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

[0069] ● The modulation ratio is dynamically adjusted according to the motor speed / torque command.

[0070] S23. Under parking conditions, when a load is detected connected to the single-phase AC output port AC_OUT, the system enters AC power supply mode:

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

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

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

[0074] S3. Implement a two-way energy control strategy.

[0075] S31, Energy control in charging mode:

[0076] S311. The phase of the grid voltage is acquired through an AC-side voltage sensor and subjected to dual closed-loop PI regulation with the DC-side voltage setpoint. In other words, the charging system includes a function to acquire the grid voltage phase.

[0077] Voltage sensor with voltage phase;

[0078] S312. Generate the switching signal for the AC / AC converter, enabling the grid current to track the sinusoidal reference.

[0079] Waveform (THD < 5%), total harmonic distortion < 5%;

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

[0081] S314. By using the ANPC midpoint potential balance algorithm, the charging and discharging time of C1 / C2 is adjusted in real time to control the bus voltage fluctuation within ±2%.

[0082] S32, Inverter control in power-off mode:

[0083] S321: Employs carrier PWM technology to dynamically adjust the motor speed / torque according to motor speed / torque commands.

[0084] The ratio is controlled, and switching signals S1-S18 are generated;

[0085] S322, Introducing third harmonic injection to improve voltage utilization;

[0086] S323. Modulation wave is corrected by neutral point voltage injection method to maintain voltage balance of bus capacitor.

[0087] S4. Achieve synergy between hardware reuse and security protection.

[0088] S41, Hardware reuse mechanism:

[0089] In charging mode and parking power supply mode, the motor's A-phase winding is used as a filter inductor.

[0090] It is connected in series with the output of a single-phase AC / AC converter.

[0091] S42, Multi-mode safety interlock:

[0092] S421. During the mode switching transition period (<100μs), a dead time is forcibly inserted and strictly controlled.

[0093] The grid starts each functional module according to the power-on sequence;

[0094] S422: Real-time monitoring of the junction temperature of the SiC-MOSFET silicon carbide module and the temperature rise of the motor windings.

[0095] Safety policy is triggered when the temperature exceeds 125°C;

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

[0097] The above-mentioned topological architecture innovations have led to the following core technical means:

[0098] Motor winding reuse mechanism: The three-phase windings of the motor are reconstructed into charging filter inductors to realize cross-scenario reuse of hardware resources; the traditional OBC is eliminated; the three-level ANPC is directly connected to the charging port topology: the power circuit is selected and switched through the contactor; forming a new overall architecture of "battery-inverter-isolated AC / AC-grid".

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

[0100] Two-way power control: In parking power supply mode, the high voltage of the battery is converted to 220V AC through a three-level ANPC and an AC / AC converter to meet the needs of multiple scenarios.

[0101] Seamless mode switching technology: Based on the control strategy algorithm of finite state machine (FSM), it ensures smooth switching between charging, power supply and electric drive modes, which means better control of the contactor state.

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

[0103] In addition, this application features a safety and efficiency synergy design: strict power-on timing is implemented on both the AC and DC sides to ensure the orderly and safe operation of each functional module. Real-time monitoring of the SiC-MOSFET junction temperature and the temperature rise of the motor windings triggers a high-temperature derating / shutdown strategy.

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

[0105] The three-level active neutral clamp (ANPC) inverter has its DC side directly connected to the power battery pack and its three-phase AC output terminals connected to the motor windings.

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

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

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

[0109] An isolated AC / AC converter, including a high-frequency transformer, a SiC-MOSFET-based totem-pole PFC power factor correction module and an H-bridge inverter module, as well as an LC output filter;

[0110] The controller is 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 clamp (ANPC) inverter has 18 SiC-MOSFETs (S1-S18), divided into three groups of parallel three-phase branches, with 6 SiC-MOSFETs in each group. In each phase, there are 4 series-connected switching SiC-MOSFETs on the main bridge arm. Then, the two middle SiC-MOSFETs on the main bridge arm are connected in parallel with 2 clamping SiC-MOSFETs. As shown in the circuit diagram, on phase A, S1, S2, S3, and S4 are connected in series, and 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 supporting capacitor C1 / C2 to achieve clamping. The point between S2 and S3 is connected to the motor phase A branch. The other phases are connected in the same way as phase A.

[0112] The H-bridge inverter module is preferably based on SiC-MOSFETs, comprising four parallel bridge arms, each with two SiC-MOSFETs connected in series. A voltage-regulating capacitor is connected in parallel between the left and right bridge arms. The two left bridge arms are electrically connected to an LC output filter. The point between the capacitor and inductor of this filter serves as the single-phase AC output port AC_OUT, and the other side of the capacitor serves as the return neutral port N. However, in this AC / AC converter, the return output port is not grounded. The return neutral port N is electrically connected to the point between contactor K2 and the A-phase winding of the motor. The single-phase AC output port AC_OUT is connected in series with contactor K1, and contactor K2 is connected in series in the A-phase branch. Contactor K1 is connected in series between the point on the A-phase branch and the single-phase AC output port (AC_OUT). The two right bridge arms are also electrically connected to an LC output filter and connected to one side of the high-frequency transformer. The power factor correction module is also preferably based on SiC-MOSFETs, consisting of four parallel bridge arms. A voltage-regulating capacitor is connected in parallel between the left and right bridge arms. The difference is that each of the two left bridge arms has two SiC-MOSFETs connected in series, while one of the two right bridge arms has two IGBTs connected in series, and the other has two SiC-MOSFETs connected in series. The two left bridge arms are connected to an LC output filter and then to one side of the high-frequency transformer, while the two right bridge arms are connected to the power grid via an inductor filter circuit. LC filters are connected to both sides of the high-frequency transformer, thus forming a CLLC-type isolated high-frequency transformer module.

[0113] Through the design of the various circuit modules described above, the entire new charging system is formed. The system integration is significantly improved, and it possesses all the aforementioned advantages.

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

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

[0116] 1. Understanding basic concepts

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

[0118] Speed ​​and torque commands: Motor control systems typically use speed and torque commands to adjust the motor's operating state.

[0119] 2. Establish a control model

[0120] Determine the motor's operating status: Based on the motor's speed and torque commands, the current operating status of the motor needs to be determined first through control algorithms (such as PID control, fuzzy control, etc.).

[0121] Calculate the required output voltage: Based on the motor's load characteristics and speed / torque requirements, calculate the required output voltage.

[0122] 3. Dynamically adjust the modulation ratio

[0123] Adjust the modulation ratio according to voltage requirements: Calculate the modulation ratio using the following formula:

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

[0125] Modulation ratio adjustment: The modulation ratio is dynamically adjusted based on real-time speed and torque feedback to ensure that the output voltage meets the motor's operating requirements.

[0126] 4. Implement control strategies

[0127] PWM control: In three-level active neutral-point clamped inverters, pulse width modulation (PWM) technology is typically used to generate the desired output voltage waveform. The duty cycle of the PWM is adjusted based on the calculated modulation ratio.

[0128] Real-time monitoring: Sensors are used to monitor the motor's speed and torque in real time, ensuring that the control system can respond quickly to changes.

[0129] 5. Factors to be considered

[0130] Overload and protection mechanisms: When adjusting the modulation ratio, it is necessary to consider overload conditions and protection mechanisms to avoid damage to the inverter and motor.

[0131] Thermal management: High modulation ratio operation may cause the inverter to overheat, so an effective heat dissipation solution needs to be designed.

[0132] Filtering and Harmonic Control: Although three-level inverters can reduce harmonics, filters are still needed to further reduce the impact of harmonics.

[0133] 6. Implementation and Verification

[0134] Simulation testing: Before practical application, simulation software is used to test and verify the effectiveness of the control algorithm and modulation ratio adjustment.

[0135] Field testing: Conduct field tests on the experimental platform and adjust parameters 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 clamp inverter can be dynamically adjusted according to the motor speed and torque commands, thereby achieving efficient motor drive.

[0137] Furthermore, in grid charging mode and parking power supply mode, K2 is first disconnected, K1 is closed, and the AC / AC converter is started after a 50ms delay, followed by a 50ms delay before starting the three-level active midpoint clamp inverter; in electric drive mode, K1 is first disconnected, K2 is closed, and the three-level active midpoint clamp inverter is started after a 50ms delay; in all modes, the SiC-MOSFET junction temperature is monitored, and temperature protection is triggered when the junction temperature is >125℃.

[0138] In the grid charging mode, the motor windings are configured as charging filter inductors, and the equivalent inductance value of the motor windings is determined by the motor itself, such as 3mH, 4mH, etc.

[0139] Specific implementation examples:

[0140] In grid charging mode:

[0141] Disconnect K2 and close K1. The AC power is converted into direct battery charging 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 make the battery voltage adaptively match the grid-side equivalent voltage;

[0143] In power supply mode during shutdown:

[0144] Disconnect K2 and close K1. The battery DC power is inverted to AC power by the ANPC inverter, and then adjusted to 220V AC output by the AC / AC converter and power factor correction.

[0145] In electric drive mode:

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

[0147] Mode switching logic:

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

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

[0150] Security protection strategies include:

[0151] Power-on sequence control:

[0152] In grid-connected mode, K2 is disconnected first, K1 is closed, the AC / AC converter is started after a 50ms delay, and the ANPC converter is started after another 50ms delay.

[0153] In electric drive mode, K1 is disconnected first, K2 is closed, and the ANPC converter is started after a 50ms delay.

[0154] Thermal management strategy:

[0155] The junction temperature (T_j) of the SiC-MOSFET is monitored. When T_j > 125℃, temperature protection is triggered (50% power → shutdown).

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

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

[0158] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A charging system based on motor winding multiplexing, characterized by, The three-level active neutral point clamped inverter, the power battery pack electrically connected to the DC side of the three-level active neutral point clamped inverter, the motor winding electrically connected to the three-phase output end of the AC side of the three-level active neutral point clamped inverter, and the AC / AC converter electrically connected to the other side of the motor winding, further comprise 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 multiplexing of claim 1, wherein, The mode switching module comprises a contactor K1 and a contactor K2, the contactor K2 is connected to one phase branch of the motor winding and the phase branch is electrically connected to the output end of the AC / AC converter, and the contactor K1 is connected between the phase branch and the output end of the AC / AC converter.

3. The charging system based on motor winding multiplexing of claim 2, wherein, The AC / AC converter is an isolated converter, specifically comprising a power factor correction module, an isolated transformer module, an inverter module and an LC output filter.

4. The charging system based on motor winding multiplexing of claim 3, wherein, The inverter module is an H full-bridge inverter module.

5. The charging system based on motor winding multiplexing of claim 3, wherein, The charging system further comprises 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 multiplexing of claim 1, wherein, The three-level active neutral point clamped inverter has 18 SiC-MOSFETs, and each phase has 6 SiC-MOSFETs.

7. The charging system based on motor winding multiplexing of claim 6, wherein, 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 charging system based on motor winding multiplexing of claim 3, wherein, The contactor K2 is connected in series in the branch of the motor A phase, and the contactor K1 is connected between the point of the A phase branch and the single-phase AC output port AC_OUT.

9. The charging system based on motor winding multiplexing of claim 8, wherein, The neutral port N of the AC / AC converter is electrically connected to the point between the contactor K2 and the motor A phase winding.

10. The charging system based on motor winding multiplexing of claim 1, wherein, The motor winding is configured as a filter inductor in the grid charging mode.

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