Powertrain, motor controllers and electric vehicles

Abstract

A powertrain, motor controller, and electric vehicle are disclosed, relating to the field of new energy vehicle technology. The motor controller housing is used to fix two first copper busbars, three second copper busbars, and one third copper busbar. The two first copper busbars are used to electrically connect at least one positive and negative terminal of a power battery or DC power supply to the DC terminal of a three-phase power module. The three second copper busbars are respectively used to electrically connect the three-phase AC terminal of the three-phase power module to the three-phase windings of the drive motor. One end of the third copper busbar is used to electrically connect to the neutral point of the three-phase windings of the drive motor, and the other end of the third copper busbar is used to electrically connect to the positive terminal of a freewheeling diode. The negative terminal of the freewheeling diode is used to electrically connect to the DC terminal of the three-phase power module, and the freewheeling diode is used to forward conduct the electrical connection between the neutral point of the three-phase windings and at least one DC input terminal of the three-phase power module. According to this solution, arcing is avoided, improving the reliability and safety of the charging system.

Description

Technical Field

[0001] This application relates to the field of electric vehicles, and more specifically, to a powertrain, a motor controller, and an electric vehicle. Background Technology

[0002] With the increasing popularity of electric vehicles, the safety and reliability of charging systems have become a key research focus. Currently, mainstream charging piles typically output 250A, but with the rapid development of battery technology, battery pack voltage and capacity are constantly increasing, making fast charging increasingly urgent. Taking a 630V rated voltage, 80kWh battery pack as an example, the battery's rated current is 127Ah, and the charging current required for 3C~5C fast charging is 381A~635A. However, existing mainstream charging piles cannot meet this fast charging demand. Therefore, current methods reuse powertrain components to increase the lower input voltage to a higher output current to meet fast charging requirements. However, during the buck-boost charging process, if a fault occurs in the circuit, the relay may abnormally disconnect, and the energy stored in the inductor cannot be released. The disconnected relay may cause arcing, leading to safety issues during electric vehicle charging.

[0003] Therefore, how to safely disconnect the circuit after a fault occurs during the step-down charging process of electric vehicles is a problem that needs to be solved. Summary of the Invention

[0004] This application provides a powertrain, motor controller, and electric vehicle. By adding a freewheeling diode to the neutral point of the drive motor, a freewheeling path is formed when the charging switch is abnormally disconnected, releasing inductor energy and preventing arcing. This avoids burning out the charging circuit and potential safety hazards in the charging system, effectively solving safety issues during the step-down charging process and improving the reliability and safety of the charging system.

[0005] In a first aspect, this application provides a powertrain for a DC-compatible electric vehicle. The powertrain includes a motor controller and a drive motor. The motor controller controls the drive motor using power supplied by the electric vehicle's power battery and charges the electric vehicle's power battery using power supplied by a DC power source. The motor controller includes a motor controller housing, which houses a bus capacitor, a three-phase power module, and a freewheeling diode. The bus capacitor receives power from the power battery and outputs DC power to the three-phase power module. The motor controller housing secures two first copper busbars, three second copper busbars, and one third copper busbar. The two first copper busbars electrically connect at least one of the positive and negative terminals of the power battery or the DC power source to the DC terminals of the three-phase power module. The three second copper busbars electrically connect the three-phase AC terminals of the three-phase power module to the three-phase windings of the drive motor. One end of the third copper busbar is used to electrically connect to the neutral point of the three-phase winding of the drive motor, and the other end of the third copper busbar is used to electrically connect to the positive terminal of the freewheeling diode. The negative terminal of the freewheeling diode is used to electrically connect to the DC terminal of the three-phase power module. The freewheeling diode is used to forward conduct the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module.

[0006] The motor controller housing is used to fix two first copper busbars, three second copper busbars, and one third copper busbar. The number of copper busbars is set as needed; the number in this application is only the number necessary for implementing the scheme. The two first copper busbars are the DC input terminals of the motor controller, used to electrically connect to the positive and negative terminals of the power battery, respectively, and also used to electrically connect to the positive and negative terminals of the DC power supply, respectively. The motor controller is used to receive power from the power battery or DC power supply, or to output current to the power battery, through the two first copper busbars. The three second copper busbars are used to electrically connect the three-phase AC terminals of the three-phase power module to the three-phase windings of the drive motor. The three-phase power module is the three-phase bridge arm of the motor controller. The two ends of each phase bridge arm are used to connect to the positive and negative terminals of the power battery, and the midpoints of the three bridge arms are used to connect to the three-phase windings of the drive motor, that is, the three-phase AC terminals of the three-phase power module and the three-phase windings of the drive motor are electrically connected through the three second copper busbars.

[0007] The powertrain is used to receive DC power output from a DC power source and charge the power battery of the electric vehicle. The powertrain includes a motor controller and a drive motor. The motor controller includes three-phase bridge arms connected in parallel. The two ends of each phase bridge arm are used to connect to the positive and negative terminals of the power battery. The midpoints of the three bridge arms are used to connect to the three-phase windings of the drive motor.

[0008] The powertrain includes a motor controller and a drive motor. The motor controller comprises three-phase bridge arms connected in parallel. Each bridge arm includes two electronic switching devices connected in series. The midpoint of the bridge arm is the connection point between the two electronic switching devices. These electronic switching devices are composed of insulated-gate bipolar transistors and anti-parallel diodes, or other electronic components. The midpoints of the three-phase bridge arms of the motor controller are connected one-to-one with the three-phase windings of the drive motor. The two ends of the motor controller are connected to the two ends of the power battery, allowing the motor controller to receive current from the power battery or output current to the power battery. The neutral point of the three-phase windings is the core node of the drive motor's electrical structure and is the common connection point of the three-phase stator windings. The stator windings of the drive motor consist of three symmetrical coils, and the neutral point of the three-phase windings is the common point of the star connection of the three-phase windings. The neutral point of the three-phase windings is also called the center tap or star point, etc., without limitation here.

[0009] One end of the third copper busbar is used to electrically connect to the neutral point of the three-phase winding of the drive motor, and the other end is used to electrically connect to the positive terminal of the freewheeling diode. The negative terminal of the freewheeling diode is used to electrically connect to the DC terminal of the three-phase power module. The freewheeling diode is used to forward conduct the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module. That is, the neutral point of the three-phase winding is also connected to one end of each phase arm of the three-phase bridge arm through the freewheeling diode. One end of the freewheeling diode is connected to the neutral point of the three-phase winding, and the other end of the freewheeling diode is connected to one end of the three-phase bridge arm.

[0010] In another implementation, one end of the third copper busbar is used to electrically connect to the neutral point of the three-phase winding of the drive motor, and the other end of the third copper busbar is used to electrically connect to the negative terminal of the freewheeling diode. The positive terminal of the freewheeling diode is used to electrically connect to the DC terminal of the three-phase power module. The freewheeling diode is used to forward conduct the electrical connection between at least one DC input terminal of the three-phase power module and the neutral point of the three-phase winding.

[0011] According to the solution of this application, by adding a freewheeling diode to the neutral point of the drive motor, the freewheeling diode is connected to the neutral point of the drive motor and the DC terminal of the three-phase power module through a third copper busbar, thereby conducting the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module. The structure is simple, the cost is low, and the reliability and safety of the charging system are improved.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the powertrain includes a diode holder disposed on the side wall or bottom of the motor controller housing, the pin of the freewheeling diode being fixed to the diode holder, one pin of the freewheeling diode being electrically connected to at least one DC input terminal of the three-phase power module via a lead, and the other pin of the freewheeling diode being electrically connected to a third copper busbar via another lead.

[0013] The two leads of the freewheeling diode are fixed inside the motor controller housing by diode mounting brackets. One lead of the freewheeling diode is electrically connected to at least one DC input terminal of the three-phase power module via a lead, and the other lead of the freewheeling diode is electrically connected to a third copper busbar via another lead. Thus, the freewheeling diode conducts the connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, during the process of the powertrain receiving current from the DC power supply to charge the power battery, when a powertrain malfunctions, the switching transistors of the three-phase bridge arms of the three-phase power module are all turned off, and at least one phase bridge arm of the three-phase power module, the freewheeling diode, the three-phase winding of the drive motor, and the bus capacitor form a discharge circuit.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the neutral point of the drive motor is also used to connect to the positive or negative terminal of the power battery via a charging switch. When the powertrain is used to drive the electric vehicle, the charging switch is open, and the three-phase arms of the three-phase power module receive power from the power battery and output drive current to the three-phase windings through the midpoint of the three arms. When the powertrain receives DC power from the DC power supply to charge the power battery, the charging switch is closed, and the powertrain charges the power battery by reducing the voltage of the DC power.

[0016] The neutral point of the three-phase winding is connected to either the positive or negative terminal of the power battery via a charging switch. The neutral point of the three-phase winding is also connected to one end of each phase arm of the three-phase bridge via a freewheeling diode. The neutral point of the three-phase winding is connected to one end of the power battery via the charging switch, and the power battery receives current from the neutral point of the three-phase winding through the charging switch.

[0017] During charging, the motor controller receives power from the DC power supply and outputs current to the power battery through the drive motor. The neutral point of the three-phase windings of the drive motor outputs current to the power battery through the charging switch. The three-phase windings of the drive motor act as inductors, storing energy during charging. If a fault occurs in the charging circuit, the charging switch will abnormally open, and the energy stored in the three-phase windings as inductors cannot be released. The disconnected charging switch may trigger arcing. Arcing, also known as electric arc discharge, is a gas discharge phenomenon in which current continues to flow in the gap of an open circuit. When a sufficiently high voltage is applied to the contacts, switches, or conductor gaps in the circuit, the air or other medium in the gap will be ionized into plasma. Even if the contacts have separated, the current can continue to flow, accompanied by high temperature, strong light, and electromagnetic radiation. When the charging switch is opened, because the three-phase windings in the charging circuit are equivalent to inductors, the current cannot change abruptly, inducing a high voltage. The voltage between the contacts of the charging switch rises instantaneously, breaking down the gap and forming an arc, leading to safety problems during the charging of electric vehicles.

[0018] To achieve fast charging, during the buck-boost charging process, due to the high current, when the charging switch is abnormally disconnected, the charging switch is more likely to experience arcing because the three-phase windings act as inductors. Therefore, an additional freewheeling path is needed to release the energy in the inductor.

[0019] During the charging process, when the charging switch is turned off, the energy stored in the three-phase windings can be released from the neutral point of the three-phase windings through the freewheeling diode, thus preventing the charging switch from arcing.

[0020] According to the solution of this application, by adding a freewheeling diode to the neutral point of the drive motor, the freewheeling diode is connected to the neutral point of the drive motor and the DC terminal of the power module through a third copper busbar. When the charging switch is abnormally disconnected, a freewheeling path is formed to release the inductor energy and avoid arcing. This avoids the burning out of the charging switch and the safety hazards of the charging system. The structure is simple and the cost is low. It effectively solves the safety problems caused by abnormal disconnection of the switch during the charging process and improves the reliability and safety of the charging system.

[0021] During the operation of an electric vehicle, the motor controller receives DC power from the power battery and outputs drive current to the drive motor through the midpoint of the three bridge arms. At this time, the charging switch is turned off, and the neutral point of the three-phase winding is disconnected from one end of the power battery. Because the freewheeling diode has a reverse cutoff function, the current from one end of the three-phase bridge arm of the motor controller to the neutral point of the three-phase winding is cut off by the freewheeling diode, which does not affect the drive current output by the motor controller to the drive motor.

[0022] During the charging process of an electric vehicle, the vehicle is stationary and the drive motor does not output torque. When the electric vehicle is connected to a DC power source, if the voltage of the DC power source is higher than the voltage of the power battery, in order to meet the requirements of fast charging, the lower input voltage is boosted to a higher output current. At this time, the three-phase windings of the drive motor are reused to perform step-down and step-up charging of the power battery. The powertrain is used to reduce the voltage of the DC power supply through the drive motor and charge the power battery. The step-down and step-up charging process mainly includes two stages. In one stage, the three-phase windings of the drive motor are equivalent to inductors and are in a charging state. At this time, the DC power supply charges both the three-phase windings of the drive motor and the power battery simultaneously. The voltage across the power battery is lower than the output voltage of the DC power supply. The sum of the voltage across the power battery and the voltage across the three-phase windings equals the output voltage of the DC power supply. In another phase, the three-phase windings of the drive motor act as a power source, discharging. Since the voltage of the three-phase windings during charging was lower than the DC power supply output voltage, the voltage remains lower than the DC power supply voltage when the three-phase windings discharge to charge the power battery. The voltage of the three-phase windings decreases until the charging voltage of the power battery equals the voltage of the three-phase windings. Thus, the motor controller and drive motor alternately operate in these two phases to perform step-down charging of the power battery. During this charging process, due to the reverse cutoff effect of the freewheeling diode, the current from one end of the three-phase bridge arm of the motor controller to the neutral point of the three-phase windings is cut off by the freewheeling diode, ensuring that the neutral point of the three-phase windings continues to charge the power battery through the charging switch.

[0023] According to the solution in this application, the freewheeling diode added to the neutral point of the drive motor will not affect the operation of the powertrain in driving and normal charging states. When the charging switch is abnormally disconnected, arcing is avoided, effectively solving the safety problem caused by abnormal disconnection of the switch during step-down charging. At the same time, it does not affect the normal operation in other states, thus improving the reliability and safety of the charging system.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, the powertrain bus capacitor is used to connect the two ends of each phase arm of the three-phase bridge arm. When the charging switch is off, the neutral point of the three-phase winding is used to discharge to the bus capacitor through the freewheeling diode.

[0025] The powertrain bus capacitor connects to both ends of each phase arm of the three-phase bridge arm. Correspondingly, the bus capacitor is also connected to both ends of the power battery. The bus capacitor dynamically balances the bus energy through charging and discharging, suppresses voltage fluctuations caused by sudden load changes and power device switching, maintains a stable DC bus voltage, and utilizes capacitive reactance to create a low-impedance path for AC ripple in the input DC, filtering out ripple components from rectification residues or high-frequency switching, and reducing current distortion and electromagnetic interference. The bus capacitor can filter and regulate the power battery voltage, and can also temporarily store or release energy, acting as an energy buffer. During normal operation of the electric vehicle, the bus capacitor receives power from the power battery and supplies power to other components.

[0026] When the charging switch is turned off, the neutral point of the three-phase winding releases the energy of the inductor through the freewheeling diode, the bus capacitor, and the body diode of the three-phase bridge arm, so that the energy in the inductor will not affect the timely disconnection of the charging switch.

[0027] According to the solution of this application, by adding a freewheeling diode to the neutral point of the drive motor, a freewheeling path is formed between the freewheeling diode and the bus capacitor when the charging switch is abnormally disconnected, releasing the inductor energy and avoiding arcing. This avoids the burning out of the charging switch and potential safety hazards in the charging system. By using the bus capacitor in the powertrain as the freewheeling path, no additional capacitor is needed, reducing costs and effectively solving the safety problems caused by abnormal disconnection of the switch during charging, thereby improving the reliability and safety of the charging system.

[0028] In conjunction with the first aspect, in some implementations of the first aspect, one end of the bus capacitor is used to connect to the positive terminal of the power battery, and the other end of the bus capacitor is used to connect to the negative terminal of the power battery. The neutral point of the three-phase winding is used to connect to the positive terminal of the power battery through a charging switch. The freewheeling diode is used to unidirectionally conduct the current from the neutral point of the three-phase winding to one end of the bus capacitor.

[0029] A freewheeling diode is connected between the neutral point of the three-phase winding of the drive motor and the positive terminal of the power battery. The freewheeling diode is used to unidirectionally conduct the current from the neutral point of the three-phase winding to one end of the bus capacitor. When the charging switch is off, the current in the three-phase winding flows from the neutral point of the three-phase winding through the freewheeling diode, the bus capacitor, the body diodes of the three lower arms of the three-phase bridge arm, and the midpoint of the three-phase bridge arm back to the three-phase bridge arm, forming a freewheeling circuit and releasing the inductive energy of the three-phase winding.

[0030] According to the solution of this application, a freewheeling diode is connected to the neutral point of the three-phase winding to the positive terminal side of the power battery. The bus capacitor in the powertrain is used as the freewheeling path, eliminating the need for additional capacitors and reducing costs. When the charging switch is abnormally disconnected, arcing is avoided, thus preventing the charging switch from burning out and potential safety hazards in the charging system. This effectively solves the safety problems caused by abnormal disconnection of the switch during charging and improves the reliability and safety of the charging system.

[0031] In conjunction with the first aspect, in some implementations of the first aspect, one end of the bus capacitor is used to connect to the negative terminal of the power battery, and the other end of the bus capacitor is used to connect to the positive terminal of the power battery. The neutral point of the three-phase winding is used to connect to the negative terminal of the power battery through a charging switch. The freewheeling diode is used to unidirectionally conduct the current from one end of the bus capacitor to the neutral point of the three-phase winding.

[0032] A freewheeling diode is connected between the neutral point of the three-phase winding of the drive motor and the negative terminal of the power battery. The freewheeling diode is used to unidirectionally conduct the current from one end of the bus capacitor to the neutral point of the three-phase winding. When the charging switch is off, the current in the three-phase winding flows from the neutral point of the three-phase winding through the midpoint of the three-phase bridge arm, the body diodes of the three upper bridge arms of the three-phase bridge arm, the bus capacitor, and the freewheeling diode back to the neutral point of the three-phase winding, forming a freewheeling circuit and releasing the inductive energy of the three-phase winding.

[0033] According to the solution of this application, a freewheeling diode is connected to the negative terminal side of the power battery at the neutral point of the three-phase winding, and the bus capacitor in the powertrain is used as the freewheeling path. No additional capacitor is required, which reduces the cost. When the charging switch is abnormally disconnected, arcing is avoided, thereby avoiding the burning of the charging switch and the safety hazards of the charging system. This effectively solves the safety problems caused by abnormal disconnection of the switch during charging and improves the reliability and safety of the charging system.

[0034] In conjunction with the first aspect, in some implementations of the first aspect, during the process of the powertrain step-down charging the power battery, the neutral point of the three-phase winding is used to output current to the power battery through the charging switch. During the process of the powertrain step-down charging the power battery, if a powertrain malfunctions, the charging switch is disconnected, and the neutral point of the three-phase winding stops outputting current to the power battery.

[0035] During the process of the powertrain stepping down and charging the power battery, the neutral point of the three-phase winding of the drive motor is used to output current to the power battery through the charging switch. When the motor controller or drive motor malfunctions, such as a short circuit in the bridge arm or a short circuit in the bus, the charging switch needs to be disconnected in time to avoid burning out the charging circuit switch or causing safety hazards in the charging system.

[0036] The charging switch in this application is a controlled switching device, such as a switching transistor or a relay.

[0037] According to the solution in this application, when a fault occurs in the charging circuit during the step-down charging process, the charging switch needs to be disconnected. Combined with the freewheeling diode forming the freewheeling path, the charging switch can be disconnected in a timely and safe manner, effectively preventing the charging circuit switch from burning out or the charging system from posing a safety hazard, thereby improving the reliability and safety of the charging system.

[0038] In conjunction with the first aspect, in some implementations of the first aspect, the powertrain is used to charge the power battery by receiving DC power from a DC power source. During this process, a charging switch is turned on, controlling the three upper and three lower arms of the three-phase bridge arm to alternately conduct, and the three-phase windings output current to the power battery through the charging switch. When the charging switch is turned off, the three upper and three lower arms of the three-phase bridge arm are all turned off, and the three-phase windings stop outputting current to the power battery.

[0039] During the step-down charging process of the power battery, the powertrain controls the three upper and three lower arms of the three-phase bridge arm to alternately conduct, thereby causing the motor controller and drive motor to alternately operate in two stages to step-down charge the power battery. In one stage, the three-phase windings of the drive motor act as inductors and are in a charging state. At this time, the DC power supply simultaneously charges the three-phase windings of the drive motor and the power battery. The voltage across the power battery is lower than the output voltage of the DC power supply, and the sum of the voltage across the power battery and the voltage across the three-phase windings equals the output voltage of the DC power supply. In the other stage, the three-phase windings of the drive motor act as power sources and are in a discharging state. Since the voltage of the three-phase windings was lower than the output voltage of the DC power supply when charging, the voltage is still lower than the DC power supply voltage when the three-phase windings discharge to charge the power battery. The voltage of the three-phase windings decreases, and the charging voltage of the power battery equals the voltage of the three-phase windings.

[0040] When the charging switch is turned off, the three upper and three lower arms controlling the three-phase bridge arm are disconnected, thereby stopping charging and the three-phase windings stop outputting current to the power battery.

[0041] According to the solution in this application, when a powertrain malfunctions during the step-down charging process, the three-phase bridge arm of the motor controller is promptly disconnected to stop operation, thereby avoiding burnout of the charging circuit switch and potential safety hazards in the charging system. This effectively solves the safety problems caused by abnormal disconnection of the switch during the step-down and current-boosting process, and improves the reliability and safety of the charging system.

[0042] In conjunction with the first aspect, in some implementations of the first aspect, the powertrain is specifically used to control the three upper arms and three lower arms of the three-phase bridge arm to disconnect when the current through the freewheeling diode is greater than a preset current threshold.

[0043] The powertrain detects the current through the freewheeling diode. When the current through the freewheeling diode exceeds a preset current threshold, the powertrain determines that the charging switch is malfunctioning. At this point, it controls the three upper and three lower arms of the three-phase bridge arm to disconnect, stopping the charging process to prevent further damage to the charging system. Since the charging switch is not necessarily located in the motor controller but can be located in the battery pack, the motor controller cannot directly obtain the status of the charging switch. Therefore, by detecting the current through the freewheeling diode, the charging switch status can be obtained more quickly, allowing for timely adjustments to the control strategy.

[0044] According to the solution in this application, during the step-down charging process, the current through the freewheeling diode is detected in real time, thereby obtaining the status of the charging switch and timely controlling the three-phase bridge arm of the motor controller to disconnect and stop working. This avoids the burning out of the charging circuit switch and potential safety hazards in the charging system, effectively solving the safety problems caused by abnormal disconnection of the switch during the step-down and current-boosting process, and improving the reliability and safety of the charging system.

[0045] In conjunction with the first aspect, in some implementations of the first aspect, the powertrain is specifically used to control the three upper arms and three lower arms of the three-phase bridge arm to disconnect when the voltage to ground at the neutral point of the three-phase winding is greater than a preset voltage threshold.

[0046] The powertrain detects the voltage to ground at the neutral point of the three-phase windings. When this voltage exceeds a preset threshold, the motor controller determines that the charging switch is malfunctioning. At this point, the three upper and three lower arms of the three-phase bridge arm are disconnected, stopping the charging process to prevent further damage to the charging system. Since the charging switch may be located within the battery pack rather than the motor controller, and the controller cannot directly access its status, detecting the voltage to ground at the neutral point of the three-phase windings allows for faster acquisition of the charging switch status and timely adjustment of the control strategy.

[0047] According to the solution in this application, during the step-down charging process, the voltage to ground of the neutral point of the three-phase winding is detected in real time, thereby obtaining the status of the charging switch and timely controlling the three-phase bridge arm of the motor controller to disconnect and stop working. This avoids the burning out of the charging circuit switch and the safety hazards of the charging system, effectively solves the safety problems caused by abnormal disconnection of the switch during the step-down and current-boosting process, and improves the reliability and safety of the charging system.

[0048] In conjunction with the first aspect, in certain implementations of the first aspect, the powertrain is specifically used to charge the power battery by the following methods during the process of the powertrain stepping down and charging the power battery: when the three upper arms of the three-phase bridge arm are turned on, the DC power supply charges the three-phase windings and the power battery; when the three lower arms of the three-phase bridge arm are turned on, the three-phase windings charge the power battery. When the charging switch is turned off, the three-phase windings are used to discharge to the bus capacitor through the freewheeling diodes and the three upper arms or the three lower arms.

[0049] In conjunction with the first aspect, in some implementations of the first aspect, at least one end of each phase arm of the three-phase bridge arm is used to connect to the positive or negative terminal of the power battery via a first switch. At least one end of each phase arm of the three-phase bridge arm is used to connect to the positive or negative terminal of a DC power supply via a second switch.

[0050] The first switch includes one or more switches. One end of each phase of the three-phase bridge arm is connected to the positive terminal of the power battery via the first switch, or one end of each phase of the three-phase bridge arm is connected to the negative terminal of the power battery via the first switch, or one end of each phase of the three-phase bridge arm is connected to the positive terminal of the power battery via a first switch, and the other end of each phase of the three-phase bridge arm is connected to the negative terminal of the power battery via another first switch. The first switch is used to control the connection between the power battery and the motor controller.

[0051] The second switch includes one or more switches. One end of each phase of the three-phase bridge arm is connected to the positive terminal of the DC power supply via the second switch, or one end of each phase of the three-phase bridge arm is connected to the negative terminal of the DC power supply via the second switch, or one end of each phase of the three-phase bridge arm is connected to the positive terminal of the DC power supply via a second switch, and the other end of each phase of the three-phase bridge arm is connected to the negative terminal of the DC power supply via another second switch. The second switch is used to control the connection between the DC power supply and the motor controller.

[0052] It should be understood that the first switch, the second switch, and the charging switch can be located within the power battery pack, the high-voltage power distribution unit, the powertrain, or separately, and this application does not limit this.

[0053] In conjunction with the first aspect, in certain implementations of the first aspect, during the process of the powertrain receiving power from the battery to drive the electric vehicle, the first switch is turned on, the second switch is turned off, and the charging switch is turned off. During the process of the powertrain receiving DC power to charge the battery, the first switch, the second switch, and the charging switch are all turned on.

[0054] During the process of the powertrain driving the electric vehicle, the powertrain receives power from the battery, the first switch is turned on, and the second switch and the charging switch are turned off. During the process of the powertrain being reused to charge the battery by step-down charging, the first switch, the second switch, and the charging switch are all turned on.

[0055] Secondly, this application provides a motor controller compatible with DC charging. The motor controller is used to control the drive motor of an electric vehicle using power supplied by the vehicle's power battery and to charge the vehicle's power battery using DC power. The motor controller includes a motor controller housing, which houses a bus capacitor, a three-phase power module, and a freewheeling diode. The bus capacitor receives power from the power battery and outputs DC power to the three-phase power module. The motor controller housing secures two first copper busbars, three second copper busbars, and one third copper busbar. The two first copper busbars electrically connect at least one positive and negative terminal of the power battery or DC power supply to the DC terminal of the three-phase power module. The three second copper busbars electrically connect the three-phase AC terminal of the three-phase power module to the three-phase winding of the drive motor. One end of the third copper busbar electrically connects to the neutral point of the three-phase winding of the drive motor, and the other end electrically connects to the negative terminal of the freewheeling diode. The positive terminal of the freewheeling diode electrically connects to the DC terminal of the three-phase power module, and the freewheeling diode forward conducts the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module.

[0056] In conjunction with the second aspect, in some implementations of the second aspect, during the process of the powertrain receiving current from the DC power supply to charge the power battery, when a powertrain malfunctions, the switching transistors of the three-phase bridge arms of the three-phase power module are all turned off, and at least one phase bridge arm of the three-phase power module, the freewheeling diode, the three-phase winding of the drive motor, and the bus capacitor form a discharge circuit.

[0057] Thirdly, this application provides an electric vehicle comprising a power battery, a first switch, a second switch, and a powertrain as described in the first aspect and its various implementations. The first switch is used to connect or disconnect at least one end of each phase arm of the three-phase bridge arm and the power battery. The second switch is used to connect or disconnect a DC power supply and at least one end of each phase arm of the three-phase bridge arm. The powertrain is used to receive power from the power battery via the first switch to drive the electric vehicle. The powertrain is also used to receive power from the DC power supply via the second switch and to reduce the voltage of the DC power output from the DC power supply to charge the power battery.

[0058] In conjunction with the third aspect, in some implementations of the third aspect, during the process of the powertrain receiving power from the battery to drive the electric vehicle, the first switch is turned on, the second switch is turned off, and the charging switch is turned off. During the process of the powertrain receiving DC power to charge the battery, the first switch, the second switch, and the charging switch are all turned on.

[0059] Other beneficial effects can be found in the description of the first aspect, and will not be repeated here. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of a charging scenario for an electric vehicle provided in an embodiment of this application; Figure 2 This is a schematic diagram of the powertrain provided in an embodiment of this application; Figure 3 This is an exploded view of the motor controller provided in an embodiment of this application; Figure 4 A partial structural diagram of the motor controller provided in the embodiments of this application; Figure 5 This is a schematic diagram of a buck-boost charging process provided in an embodiment of this application; Figure 6 This is a schematic diagram of another buck-boost charging process provided in an embodiment of this application; Figure 7 This is a schematic diagram of a powertrain structure provided in an embodiment of this application; Figure 8 This is a schematic diagram of another powertrain structure provided in an embodiment of this application; Figure 9 This is a schematic diagram of the current after the charging switch is turned off, provided in an embodiment of this application; Figure 10 This is another schematic diagram of the current after the charging switch is turned off, provided in an embodiment of this application. Detailed Implementation

[0061] The technical solutions in this application will now be described in conjunction with the accompanying drawings. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments.

[0062] Figure 1 This is a schematic diagram of the architecture of the electric vehicle 10 provided in the embodiments of this application.

[0063] like Figure 1 As shown, the electric vehicle 10 includes four wheels, a power battery 20, and a powertrain 30, wherein the powertrain 30 includes a motor controller 40 and a drive motor 50. During the operation of the electric vehicle 10, the powertrain 30 receives DC power from the power battery 20 and supplies power to the drive motor 50 to output torque to drive the four wheels.

[0064] During the charging process of electric vehicle 10, electric vehicle 10 is connected to DC power supply 60 via charging gun 61. Powertrain 30 receives DC power from DC power supply 60 and charges power battery 20. While electric vehicle 10 is charging, it is charged via DC power supply 60, such as a charging station. DC power supply 60 includes charging gun 61. Charging gun 61 is inserted into the charging port of electric vehicle 10, connecting charging gun 61 to power battery 20 of electric vehicle 10, and DC power supply 60 then charges power battery 20 via charging gun 61.

[0065] With the development and popularization of electric vehicles, consumers have increasingly higher demands for charging speed of power batteries. Currently, the output current of mainstream charging piles is typically 250A. However, with the rapid development of battery technology, the voltage and capacity of battery packs are constantly increasing. Taking a 630V rated voltage, 80kWh battery pack as an example, the rated current is 127Ah, and the charging current corresponding to 3C~5C fast charging requirements is 381A~635A. Therefore, existing mainstream charging piles are insufficient to meet this fast charging demand. When the voltage platform of the power battery does not match the voltage specifications of the charging pile, fast charging may be impossible. Currently, some solutions use the drive motor windings in the powertrain to step down the voltage output of the charging pile, increasing the lower input voltage to a higher output current to meet fast charging requirements. However, during charging, if a fault occurs in the circuit, the relay may abnormally disconnect, and the energy stored in the inductor cannot be released. The disconnected relay may cause arcing, leading to safety issues during electric vehicle charging.

[0066] To address the aforementioned issues, this application provides a powertrain, motor controller, and electric vehicle compatible with DC charging electric vehicles. By adding a freewheeling diode to the neutral point of the drive motor, a freewheeling path is formed when the charging switch is abnormally disconnected, releasing inductor energy and preventing arcing. This avoids burning out the charging circuit and potential safety hazards in the charging system, effectively solving safety issues during step-down charging and improving the reliability and safety of the charging system.

[0067] Figure 2 This is a schematic diagram of a powertrain provided in this application.

[0068] like Figure 2 As shown, the powertrain 30 is used to receive DC power output from the DC power supply 60 and charge the power battery 20 of the electric vehicle 10. The powertrain 30 includes a motor controller 40 and a drive motor 50. The motor controller 40 includes a three-phase power module 410, which carries the three-phase bridge arm of the motor controller. The two ends of each phase bridge arm are used to connect to the positive and negative terminals of the power battery 20. The midpoints of the three bridge arms are respectively used to connect to the three-phase windings of the drive motor 50.

[0069] Figure 3 This is an exploded view of a motor controller provided in this application. Figure 4 This is a partial structural diagram of a motor controller provided in this application.

[0070] like Figure 3 and Figure 4 As shown, the motor controller 40 includes a motor controller housing 300, which is used to house a bus capacitor 32, a three-phase power module 410, and a freewheeling diode 31. The bus capacitor 32 is used to receive power from the power battery 20 and output DC power to the three-phase power module 410. The motor controller housing 300 is used to fix two first copper busbars 320, three second copper busbars 3101, and one third copper busbar 3102.

[0071] Two first copper busbars 320 are used to electrically connect the positive and negative terminals of at least one of the power battery 20 or DC power supply 60 to the DC terminals of the three-phase power module 410. Three second copper busbars 3101 are used to electrically connect the three-phase AC terminals 4130 of the three-phase power module 410 to the three-phase windings of the drive motor 50, respectively. One end of the third copper busbar 3102 is used to electrically connect the neutral point of the three-phase windings of the drive motor 50, and the other end of the third copper busbar 3102 is used to electrically connect the positive terminal of the freewheeling diode 31. The negative terminal of the freewheeling diode 31 is used to electrically connect the DC terminals of the three-phase power module 410. The freewheeling diode 31 is used to forward conduct the electrical connection between the neutral point of the three-phase windings and at least one DC input terminal of the three-phase power module 410.

[0072] The three-phase power module 410 includes a three-phase AC terminal 4130, which is electrically connected to the power transistors in the three-phase power module 410. The three-phase AC terminal 4130 is the AC output terminal of the three-phase power module 410. The three-phase AC terminal 4130 is electrically connected to three second copper busbars 3101.

[0073] The motor controller 40 includes a first circuit board 450, a power module 410, and a first heat sink 420 stacked between the capacitor module 400 and the first circuit board 450. The first circuit board 450 is electrically connected to the three-phase power module 410. The three-phase power module 410 is electrically connected to the copper busbar assembly 310 through a second circuit board 460. The DC power transmitted by the capacitor module 400 is converted into AC power by the three-phase power module 410, and the AC power is then transmitted to the drive motor 50 through the second circuit board 460 and the copper busbar assembly 310 in sequence. The copper busbar assembly 310 includes three second copper busbars 3101 and one third copper busbar 3102.

[0074] In one embodiment, a sidewall of the motor controller housing 300 includes a copper busbar assembly mounting hole 3001 (e.g., Figure 3As shown), one end of the copper busbar assembly 310 extends into the bottom shell 3000 through the copper busbar assembly mounting hole 3001.

[0075] In one embodiment, the capacitor module 400 further includes a capacitor housing and a bus capacitor 32 located inside the capacitor housing. One end of the capacitor connection terminal is located inside the capacitor housing and connected to the bus capacitor. The bus capacitor 32 filters the DC power. The bus capacitor 32 is electrically connected to the capacitor connection terminal. The filtered DC power is transmitted to the three-phase power module 410 through the bus capacitor 32 and the DC terminal. The three-phase power module 410 performs DC-AC conversion.

[0076] The motor controller housing 300 is used to fix two first copper busbars 320, three second copper busbars 3101, and one third copper busbar 3102. The number of copper busbars is set as needed; the number in this application is only the number necessary for implementing the scheme. The two first copper busbars 320 are the DC input terminals of the motor controller. The two first copper busbars 320 are used to electrically connect to the positive and negative terminals of the power battery 20, respectively, and are also used to electrically connect to the positive and negative terminals of the DC power supply 60, respectively. The motor controller is used to receive power from the power battery 20 or the DC power supply 60 through the two first copper busbars 320, or to output current to the power battery 20. The three second copper busbars 3101 are used to electrically connect the three-phase AC terminals 4130 of the three-phase power module 410 and the three-phase windings of the drive motor 50, respectively. The three-phase power module 410 is a three-phase bridge arm of the motor controller. The two ends of each phase bridge arm are used to connect the positive and negative terminals of the power battery 20. The midpoints of the three bridge arms are used to connect the three-phase windings of the drive motor 50, respectively. That is, the three-phase AC terminals 4130 of the three-phase power module 410 and the three-phase windings of the drive motor 50 are electrically connected through three second copper busbars 3101.

[0077] One end of the third copper busbar 3102 is used to electrically connect to the neutral point of the three-phase winding of the drive motor 50, and the other end of the third copper busbar 3102 is used to electrically connect to the positive terminal of the freewheeling diode 31. The negative terminal of the freewheeling diode 31 is used to electrically connect to the DC terminal of the three-phase power module 410. The freewheeling diode 31 is used to forward conduct the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module 410. That is, the neutral point of the three-phase winding is also connected to one end of each phase arm of the three-phase bridge arm through the freewheeling diode 31. One end of the freewheeling diode 31 is connected to the neutral point of the three-phase winding, and the other end of the freewheeling diode 31 is connected to one end of the three-phase bridge arm.

[0078] In another implementation, one end of the third copper busbar 3102 is used to electrically connect to the neutral point of the three-phase winding of the drive motor 50, and the other end of the third copper busbar 3102 is used to electrically connect to the negative terminal of the freewheeling diode 31. The positive terminal of the freewheeling diode 31 is used to electrically connect to the DC terminal of the three-phase power module 410. The freewheeling diode 31 is used to forward conduct the electrical connection between at least one DC input terminal of the three-phase power module 410 and the neutral point of the three-phase winding.

[0079] According to the solution of this application, by adding a freewheeling diode 31 to the neutral point of the drive motor 50, the freewheeling diode 31 is connected to the neutral point of the drive motor 50 and the DC terminal of the three-phase power module through the third copper busbar 3102, thus conducting the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module 410. The structure is simple, the cost is low, and the reliability and safety of the charging system are improved.

[0080] In one embodiment, the powertrain 30 includes a diode holder 480 disposed on the side wall or bottom of the motor controller housing 300. The pin of the freewheeling diode 31 is fixed to the diode holder 480. One pin of the freewheeling diode 31 is electrically connected to at least one DC input terminal of the three-phase power module 410 via a lead, and the other pin of the freewheeling diode 31 is electrically connected to a third copper busbar 3102 via another lead.

[0081] The two pins of the freewheeling diode 31 are fixed inside the motor controller housing 300 by diode mounting bracket 480. One pin of the freewheeling diode 31 is electrically connected to at least one DC input terminal of the three-phase power module 410 via a lead, and the other pin of the freewheeling diode 31 is electrically connected to the third copper busbar 3102 via another lead. Thus, the freewheeling diode 31 conducts the connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module 410.

[0082] In one embodiment, during the process of the powertrain 30 receiving current from the DC power supply 60 to charge the power battery 20, if the powertrain 30 fails, the switching transistors of the three-phase bridge arms of the three-phase power module 410 are all turned off, and at least one phase of the three-phase bridge arm of the three-phase power module, the freewheeling diode 31, the three-phase winding of the drive motor 50, and the bus capacitor 32 form a discharge circuit.

[0083] In one embodiment, the neutral point of the drive motor 50 is also used to connect to the positive or negative terminal of the power battery 20 via a charging switch. When the powertrain is used to drive the electric vehicle, the charging switch is off, and the three-phase bridge arms receive power from the power battery 20 and output drive current to the three-phase windings through the midpoint of the three bridge arms. When the powertrain receives DC power from the DC power supply 60 to charge the power battery 20, the charging switch is on, and the powertrain charges the power battery 20 by reducing the voltage of the DC power.

[0084] The neutral point of the three-phase winding is connected to the positive or negative terminal of the power battery 20 via a charging switch 21. The neutral point of the three-phase winding is also connected to one end of each phase arm of the three-phase bridge arm via a freewheeling diode 31.

[0085] The motor controller 40 includes three-phase bridge arms connected in parallel. Each bridge arm includes two electronic switching devices connected in series. The midpoint of the bridge arm is the connection point between the two electronic switching devices. The electronic switching devices are composed of insulated-gate bipolar transistors and anti-parallel diodes, or other electronic components. The midpoints of the three-phase bridge arms of the motor controller 40 are connected one-to-one with the three-phase windings of the drive motor 50. The two ends of the motor controller 40 are connected to the two ends of the power battery 20, thereby enabling the motor controller 40 to receive current from the power battery 20 or to output current to the power battery 20.

[0086] The neutral point of the three-phase winding is the core node of the electrical structure of the drive motor 50, and it is the common connection point of the ends of the three-phase stator windings. The stator windings of the drive motor 50 consist of three symmetrical coils, and the neutral point of the three-phase windings is the common point of the star connection of the three-phase windings. The neutral point of the three-phase windings is also called the center tap or star point, etc., which is not limited here.

[0087] The neutral point of the three-phase winding is connected to one end of the power battery 20 via charging switch 21. The power battery 20 receives current from the neutral point of the three-phase winding through charging switch 21. During charging, the motor controller 40 receives power from the DC power supply 60 and outputs current to the power battery 20 through the drive motor 50. The neutral point of the three-phase winding of the drive motor 50 outputs current to the power battery 20 through charging switch 21. The three-phase winding of the drive motor 50 acts as an inductor, storing energy during charging. If a fault occurs in the charging circuit, the charging switch 21 will abnormally disconnect, and the energy stored by the three-phase winding as an inductor cannot be released. The disconnected charging switch 21 may trigger arcing. Arcing, also known as electric arc discharge, is a gas discharge phenomenon in which current continues to flow in the gap of an open circuit. When a sufficiently high voltage is applied to the contacts, switches, or conductor gaps in a circuit, the air or other medium in the gap will be ionized into plasma. Even if the contacts have separated, the current can continue to flow, accompanied by high temperature, strong light, and electromagnetic radiation. When the charging switch 21 is turned off, since the three-phase winding in the charging circuit is equivalent to an inductor, the current cannot change abruptly, which will induce a high voltage. The voltage between the contacts of the charging switch 21 increases instantaneously, breaking down the gap and forming an electric arc, which leads to a safety problem during the charging process of the electric vehicle 10.

[0088] To achieve fast charging, during the buck-charge-to-boost process, due to the high current, if the charging switch 21 is abnormally disconnected, arcing is more likely to occur in the charging switch 21 because the three-phase windings act as inductors. Therefore, an additional freewheeling path is needed to release the energy in the inductor. The neutral point of the three-phase windings is also connected to one end of each phase arm of the three-phase bridge arm through a freewheeling diode 31. One end of the freewheeling diode 31 is connected to the neutral point of the three-phase windings, and the other end is connected to one end of each phase arm. During charging, when the charging switch 21 is disconnected, the energy stored in the three-phase windings can be released from the neutral point of the three-phase windings through the freewheeling diode 31, preventing arcing of the charging switch 21.

[0089] According to the solution of this application, by adding a freewheeling diode 31 to the neutral point of the drive motor 50, a freewheeling path is formed when the charging switch 21 is abnormally disconnected, releasing the inductor energy and avoiding arcing. This avoids the burning out of the charging switch 21 and potential safety hazards in the charging system. The structure is simple and the cost is low. It effectively solves the safety problems caused by abnormal disconnection of the switch during charging and improves the reliability and safety of the charging system.

[0090] Figure 5 and Figure 6 This is a schematic diagram of the current during the step-down charging process provided in an embodiment of this application.

[0091] In one embodiment, when the powertrain 30 is used to drive the electric vehicle 10, the charging switch 21 is open, and the three-phase bridge arm receives power from the power battery 20 and outputs drive current to the three-phase winding through the midpoint of the three bridge arms. When the powertrain 30 receives DC power from the DC power supply 60 to charge the power battery 20, the charging switch 21 is turned on, and the powertrain 30 reduces the voltage of the DC power through the drive motor 50 and charges the power battery 20.

[0092] During the operation of the electric vehicle 10, the powertrain 30 receives DC power from the power battery 20 and outputs drive current to the drive motor 50 through the midpoint of the three bridge arms. At this time, the charging switch 21 is open, and the neutral point of the three-phase winding is disconnected from one end of the power battery 20. Since the freewheeling diode 31 has a reverse cutoff function, the current from one end of the three-phase bridge arm of the motor controller 40 to the neutral point of the three-phase winding is cut off by the freewheeling diode 31, and it will not affect the drive current output by the motor controller 40 to the drive motor 50.

[0093] During the charging process of electric vehicle 10, electric vehicle 10 is stationary, and drive motor 50 does not output torque. When electric vehicle 10 is connected to DC power supply 60, if the voltage of DC power supply 60 is higher than the voltage of power battery 20, in order to meet the requirements of fast charging, the lower input voltage is boosted to a higher output current. At this time, the three-phase windings of drive motor 50 are reused to perform step-down charging of power battery 20. Powertrain 30 is used to reduce the DC voltage through drive motor 50 and charge power battery 20. The step-down charging process mainly includes two stages.

[0094] like Figure 5 As shown, during a certain period, the three-phase winding of the drive motor 50 is equivalent to an inductor and is in a charging state. At this time, the DC power supply 60 charges both the three-phase winding of the drive motor 50 and the power battery 20. The voltage across the power battery 20 is lower than the output voltage of the DC power supply 60. The sum of the voltage across the power battery 20 and the voltage across the three-phase winding is equal to the output voltage of the DC power supply 60.

[0095] like Figure 6 As shown, in another stage, the three-phase windings of the drive motor 50 act as a power source and are in a discharging state. Since the voltage of the three-phase windings was lower than the output voltage of the DC power supply 60 when they were charging, the voltage is still lower than the voltage of the DC power supply 60 when the three-phase windings discharge to charge the power battery 20. The voltage of the three-phase windings decreases, and the charging voltage of the power battery 20 becomes equal to the voltage of the three-phase windings. Therefore, the motor controller 40 and the drive motor 50 alternately operate in the above two stages to perform step-down charging of the power battery 20.

[0096] During the charging process described above, due to the reverse cutoff effect of the freewheeling diode 31, the current from one end of the three-phase bridge arm of the motor controller 40 to the neutral point of the three-phase winding is cut off by the freewheeling diode 31, which will not affect the output current from the neutral point of the three-phase winding to the power battery 20 for charging through the charging switch 21.

[0097] In one embodiment, during the charging of the power battery 20 by the DC power supply 60, the powertrain 30 uses a charging switch 21 to turn on, controlling the three upper and three lower arms of the three-phase bridge arm to alternately turn on, and the three-phase windings output current to the power battery 20 through the charging switch 21. When the charging switch 21 is turned off, it controls the three upper and three lower arms of the three-phase bridge arm to turn off, and the three-phase windings stop outputting current to the power battery 20.

[0098] During the step-down charging process of the power battery 20, the powertrain 30 controls the three upper and three lower arms of the three-phase bridge arm to be turned on alternately, so that the motor controller 40 and the drive motor 50 operate alternately in two stages to step-down charge the power battery 20.

[0099] like Figure 5 As shown, during one phase, the switches Q1, Q3, and Q5 of the three upper arms of the three-phase bridge arm of the motor controller 40 are turned on. The current from the DC power supply 60 flows sequentially through the three upper arms of the three-phase bridge arm, the midpoint of the three arms, the three-phase winding, the neutral point of the three-phase winding, the charging switch 21, and the power battery 20 back to the DC power supply 60. The three-phase winding of the drive motor 50 is equivalent to an inductor and is in a charging state. At this time, the DC power supply 60 simultaneously charges the three-phase winding of the drive motor 50 and the power battery 20. The voltage across the power battery 20 is lower than the output voltage of the DC power supply 60. The sum of the voltage across the power battery 20 and the voltage across the three-phase winding is equal to the output voltage of the DC power supply 60.

[0100] like Figure 6 As shown, in another stage, the switches Q2, Q4, and Q6 of the three lower arms of the three-phase bridge arm of the motor controller 40 are turned on. The current of the three-phase winding flows sequentially through the neutral point of the three-phase winding, the charging switch 21, the power battery 20, the three lower arms of the three-phase bridge arm, and the midpoint of the three arms of the three-phase bridge arm back to the three-phase winding. The three-phase winding of the drive motor 50 is equivalent to a power source and is in a discharging state. Since the voltage of the three-phase winding was lower than the output voltage of the DC power supply 60 when it was charging, the voltage of the three-phase winding is still lower than the voltage of the DC power supply 60 when it discharges to charge the power battery 20. The voltage of the three-phase winding decreases, and the charging voltage of the power battery 20 becomes equal to the voltage of the three-phase winding. Thus, the motor controller 40 and the drive motor 50 alternately operate in the above two stages to perform step-down charging of the power battery 20.

[0101] When the charging switch 21 is turned off, the switching transistors Q1, Q2, Q3, Q4, Q5 and Q6 that control the three upper bridge arms and three lower bridge arms of the three-phase bridge arm are all turned off, thereby stopping charging and the three-phase windings stop outputting current to the power battery 20.

[0102] In one embodiment, during the process of the powertrain 30 step-down charging the power battery 20, the neutral point of the three-phase winding is used to output current to the power battery 20 through the charging switch 21. During the process of the powertrain 30 step-down charging the power battery 20, if a fault occurs in the powertrain 30, the charging switch 21 is opened, and the neutral point of the three-phase winding stops outputting current to the power battery 20.

[0103] During the process of powertrain 30 stepping down and charging power battery 20, the neutral point of the three-phase winding of drive motor 50 is used to output current to power battery 20 through charging switch 21. When motor controller 40 or drive motor 50 malfunctions, such as bridge arm short circuit or bus short circuit, it is necessary to disconnect charging switch 21 in time to avoid burning out charging circuit switch or safety hazards in charging system.

[0104] During the charging process, if the charging switch 21 is abnormally disconnected, such as due to a drive failure or string failure, the energy stored in the inductor cannot be released, which may cause arcing and threaten the charging safety of electric vehicles.

[0105] In one embodiment, the powertrain 30 is specifically used to control the three upper arms and three lower arms of the three-phase bridge arm to disconnect when the current through the freewheeling diode 31 is greater than a preset current threshold.

[0106] The powertrain 30 detects the current through the freewheeling diode 31. When the current through the freewheeling diode 31 exceeds a preset current threshold, the powertrain 30 determines that the charging switch 21 is malfunctioning. At this point, it controls the three upper and three lower arms of the three-phase bridge arm to disconnect, stopping the charging process to prevent further damage to the charging system. Since the charging switch 21 is not necessarily located in the motor controller 40, but can be located in the power battery pack 20, the motor controller 40 cannot directly obtain the state of the charging switch 21. Therefore, by detecting the current through the freewheeling diode 31, the state of the charging switch 21 can be obtained more quickly, allowing for timely adjustment of the control strategy.

[0107] In one embodiment, the powertrain 30 is specifically configured to control the three upper arms and three lower arms of the three-phase bridge arm to disconnect when the voltage to ground at the neutral point of the three-phase winding is greater than a preset voltage threshold.

[0108] The powertrain 30 detects the voltage to ground at the neutral point of the three-phase windings. When this voltage exceeds a preset threshold, the powertrain 30 determines that the charging switch 21 is malfunctioning. At this point, the three upper and three lower arms of the three-phase bridge arm are disconnected, stopping the charging process to prevent further damage to the charging system. Since the charging switch 21 is not necessarily located in the motor controller 40, but can be located within the power battery pack 20, the motor controller 40 cannot directly obtain the state of the charging switch 21. Therefore, by detecting the voltage to ground at the neutral point of the three-phase windings, the state of the charging switch 21 can be obtained more quickly, allowing for timely adjustment of the control strategy.

[0109] The operating state of switching transistors Q1-Q6 is determined by detecting the current through the freewheeling diode 31 and the voltage value at the neutral point of the three-phase winding. This eliminates the need for contactor drive, contactor sticking detection, and capacitor voltage detection, simplifying the controller wiring harness and reducing costs.

[0110] By adding a freewheeling diode 31 to the neutral point of the drive motor 50 and utilizing the freewheeling path to release inductor energy, and by detecting changes in the current of the freewheeling diode 31 or the voltage change at the neutral point of the three-phase winding, the relevant circuits are promptly cut off by controlling the switching transistors Q1-Q6. This avoids burnout of the charging circuit switches and potential safety hazards in the charging system. Through real-time monitoring and rapid response, this protection circuit can effectively prevent safety hazards caused by abnormal voltage reduction and current increase, thereby improving the reliability and safety of the charging system.

[0111] Figure 7 and Figure 8 This is a schematic diagram of the powertrain 30 provided in the embodiments of this application.

[0112] In one embodiment, at least one end of each phase arm of the three-phase bridge arm is used to connect to the positive or negative terminal of the power battery 20 via a first switch 22. At least one end of each phase arm of the three-phase bridge arm is used to connect to the positive or negative terminal of a DC power supply via a second switch 23.

[0113] The first switch 22 includes one or more switches. One end of each phase of the three-phase bridge arm is connected to the positive terminal of the power battery 20 via the first switch 22, or one end of each phase of the three-phase bridge arm is connected to the negative terminal of the power battery 20 via the first switch 22, or one end of each phase of the three-phase bridge arm is connected to the positive terminal of the power battery 20 via one first switch 22, and the other end of each phase of the three-phase bridge arm is connected to the negative terminal of the power battery 20 via another first switch 22. The first switch 22 is used to control the connection between the power battery 20 and the motor controller.

[0114] The second switch 23 includes one or more switches. One end of each phase of the three-phase bridge arm is connected to the positive terminal of the DC power supply via the second switch 23, or one end of each phase of the three-phase bridge arm is connected to the negative terminal of the DC power supply via the second switch 23, or one end of each phase of the three-phase bridge arm is connected to the positive terminal of the DC power supply via one second switch 23, and the other end of each phase of the three-phase bridge arm is connected to the negative terminal of the DC power supply via another second switch 23. The second switch 23 is used to control the connection between the DC power supply and the motor controller.

[0115] It should be understood that the first switch 22, the second switch 23 and the charging switch 21 can be located in the power battery pack, the high-voltage power distribution unit or the powertrain, or can be located separately, and this application does not limit this.

[0116] In one embodiment, during the process of the powertrain 30 receiving power from the power battery 20 to drive the electric vehicle, the first switch 22 is turned on, the second switch 23 is turned off, and the charging switch is turned off. During the process of the powertrain 30 receiving DC power to charge the power battery 20, the first switch 22, the second switch 23, and the charging switch are all turned on.

[0117] During the process of the powertrain 30 driving the electric vehicle, the powertrain 30 receives power from the power battery 20, the first switch 22 is turned on, and the second switch 23 and the charging switch are turned off. During the process of the powertrain 30 performing step-down charging of the power battery 20, the first switch 22, the second switch 23, and the charging switch are all turned on.

[0118] In one embodiment, the bus capacitor 32 of the powertrain 30 is used to connect the two ends of each phase arm of the three-phase bridge arm. When the charging switch 21 is turned off, the neutral point of the three-phase winding is used to discharge to the bus capacitor 32 through the freewheeling diode 31.

[0119] The bus capacitor 32 of the powertrain 30 is used to connect the two ends of each phase arm of the three-phase bridge arm. Correspondingly, the bus capacitor 32 is also connected to the two ends of the power battery 20. The bus capacitor 32 is used to dynamically balance the bus energy through charging and discharging, suppress voltage fluctuations caused by sudden load changes and power device switching operations, maintain the stability of the DC bus voltage, and use capacitive reactance characteristics to form a low-impedance path for AC ripple in the input DC, filtering out rectifier residues or ripple components generated by high-frequency switching, and reducing current distortion and electromagnetic interference. The bus capacitor 32 can filter and regulate the voltage of the power battery 20, and can also temporarily store or release energy for energy buffering. When the electric vehicle 10 is running normally, the bus capacitor 32 receives power from the power battery 20 and supplies power to other components.

[0120] When the charging switch 21 is turned off, the neutral point of the three-phase winding releases the energy of the inductor through the freewheeling diode 31, the bus capacitor 32 and the body diode of the three-phase bridge arm, so that the energy in the inductor will not affect the timely disconnection of the charging switch 21.

[0121] In one embodiment, the powertrain 30 is specifically used to charge the power battery 20 by the following methods during the process: when the three upper arms of the three-phase bridge arm are turned on, the DC power supply 60 charges the three-phase windings and the power battery 20; when the three lower arms of the three-phase bridge arm are turned on, the three-phase windings charge the power battery 20. When the charging switch 21 is turned off, the three-phase windings are used to discharge to the bus capacitor 32 through the freewheeling diode 31 and the three upper arms or the three lower arms.

[0122] In one embodiment, such as Figure 7 As shown, one end of the bus capacitor 32 is connected to the positive terminal of the power battery 20, and the other end of the bus capacitor 32 is connected to the negative terminal of the power battery 20. The neutral point of the three-phase winding is connected to the positive terminal of the power battery 20 through the charging switch 21. The freewheeling diode 31 is used to unidirectionally conduct the current from the neutral point of the three-phase winding to one end of the bus capacitor 32.

[0123] A freewheeling diode 31 is connected to the neutral point of the three-phase winding of the drive motor 50 on the positive side of the power battery 20. The freewheeling diode 31 is used to unidirectionally conduct the current from the neutral point of the three-phase winding to one end of the bus capacitor 32.

[0124] Figure 9 This is a schematic diagram of the current after the charging switch 21 is turned off, provided in an embodiment of this application.

[0125] like Figure 9 As shown, when the charging switch 21 is turned off, the current in the three-phase winding flows from the neutral point of the three-phase winding through the freewheeling diode 31, the bus capacitor 32, the body diodes of the three lower arms of the three-phase bridge arm, and the midpoint of the three-phase bridge arm back to the three-phase bridge arm, forming a freewheeling circuit and releasing the inductive energy of the three-phase winding.

[0126] For example, when the charging switch 21 is abnormally disconnected, the inductor energy stored in the three-phase windings of the drive motor 50 may be released normally, causing a safety hazard. To solve this problem, a freewheeling diode 31 is connected to the neutral point of the three-phase windings of the drive motor 50 on the positive side of the bus. When the charging switch 21 is abnormally disconnected, the current in the three-phase windings of the drive motor 50 will form a freewheeling circuit through the freewheeling diode 31, the bus capacitor 32, and the internal diodes of the switching transistors Q2, Q4, and Q6, thereby releasing the energy in the inductor. At this time, if the current through the freewheeling diode 31 exceeds a preset current threshold, or if the voltage at the neutral point of the three-phase windings abnormally rises above a preset voltage threshold, the charging switch 21 is judged to be abnormal based on these signals, and Q1 to Q6 are immediately disconnected to stop the charging process and prevent further damage to the charging system.

[0127] In one embodiment, such as Figure 8 As shown, one end of the bus capacitor 32 is connected to the negative terminal of the power battery 20, and the other end of the bus capacitor 32 is connected to the positive terminal of the power battery 20. The neutral point of the three-phase winding is connected to the negative terminal of the power battery 20 through the charging switch 21. The freewheeling diode 31 is used to unidirectionally conduct the current from one end of the bus capacitor 32 to the neutral point of the three-phase winding.

[0128] A freewheeling diode 31 is connected between the neutral point of the three-phase winding of the drive motor 50 and the negative terminal of the power battery 20. The freewheeling diode 31 is used to unidirectionally conduct the current from one end of the bus capacitor 32 to the neutral point of the three-phase winding.

[0129] Figure 10 This is a schematic diagram of the current after the charging switch 21 is turned off, as provided in another embodiment of this application.

[0130] like Figure 10 As shown, when the charging switch 21 is turned off, the current in the three-phase winding flows from the neutral point of the three-phase winding through the midpoint of the three-phase bridge arm, the body diodes of the three upper bridge arms of the three-phase bridge arm, the bus capacitor 32, and the freewheeling diode 31 back to the neutral point of the three-phase winding, forming a freewheeling circuit and releasing the inductive energy of the three-phase winding.

[0131] For example, when the charging switch 21 is abnormally disconnected, the inductor energy stored in the three-phase windings of the drive motor 50 may be released normally, causing a safety hazard. To solve this problem, a freewheeling diode 31 is connected to the neutral point of the three-phase windings of the drive motor 50 on the negative side of the bus. When the charging switch 21 is abnormally disconnected, the current in the three-phase windings of the drive motor 50 will form a freewheeling circuit through the body diodes of the switching transistors Q1, Q3, and Q5, the bus capacitor 32, and the freewheeling diode 31, thereby releasing the energy in the inductor. At this time, if the current through the freewheeling diode 31 exceeds a preset current threshold, or if the voltage at the neutral point of the three-phase windings abnormally rises above a preset voltage threshold, the charging switch 21 is judged to be abnormal based on these signals, and Q1 to Q6 are immediately disconnected to stop the charging process and prevent further damage to the charging system.

[0132] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A powertrain for DC-compatible electric vehicles, characterized in that, The powertrain includes a motor controller and a drive motor. The motor controller is used to control the drive motor using power supplied by the electric vehicle's power battery and to charge the electric vehicle's power battery using DC power. The motor controller includes a motor controller housing, which houses a bus capacitor, a three-phase power module, and a freewheeling diode. The bus capacitor receives power from the power battery and outputs DC power to the three-phase power module. The motor controller housing is used to fix two first copper busbars, three second copper busbars, and one third copper busbar, wherein: The two first copper busbars are used to electrically connect the positive and negative terminals of at least one of the power battery or the DC power supply to the DC terminals of the three-phase power module; The three second copper busbars are respectively used to electrically connect the three-phase AC terminals of the three-phase power module and the three-phase windings of the drive motor; One end of the third copper busbar is used to electrically connect to the neutral point of the three-phase winding of the drive motor, and the other end of the third copper busbar is used to electrically connect to the positive terminal of the freewheeling diode. The negative terminal of the freewheeling diode is used to electrically connect to the DC terminal of the three-phase power module. The freewheeling diode is used to forward conduct the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the three-phase power module.

2. The powertrain according to claim 1, characterized in that, The powertrain includes a diode mounting bracket disposed on the side wall or bottom shell of the motor controller housing. The pin of the freewheeling diode is fixed to the diode mounting bracket. One pin of the freewheeling diode is electrically connected to at least one DC input terminal of the three-phase power module via a lead wire, and the other pin of the freewheeling diode is electrically connected to the third copper busbar via another lead wire.

3. The powertrain according to claim 1 or 2, characterized in that, During the process of the powertrain receiving current from the DC power supply to charge the power battery, if the powertrain malfunctions, the switching transistors of the three-phase bridge arms of the three-phase power module are all turned off, and at least one phase of the three-phase bridge arm of the three-phase power module, the freewheeling diode, the three-phase winding of the drive motor, and the bus capacitor form a discharge circuit.

4. The powertrain according to any one of claims 1-3, characterized in that, The neutral point of the drive motor is also used to connect to the positive or negative terminal of the power battery through a charging switch. When the powertrain is used to drive the electric vehicle, the charging switch is turned off, and the three-phase bridge arm of the three-phase power module is used to receive power from the power battery and output drive current to the three-phase winding through the midpoint of the three bridge arms. During the process of the powertrain receiving DC power output from the DC power source to charge the power battery, the charging switch is turned on, and the powertrain is used to reduce the voltage of the DC power output from the DC power source and charge the power battery.

5. The powertrain according to claim 4, characterized in that, During the process of the powertrain charging the power battery by stepping down the voltage, the neutral point of the three-phase winding is used to output current to the power battery through the charging switch. During the process of the powertrain charging the power battery by stepping down the voltage, if the powertrain malfunctions, the charging switch is turned off, and the neutral point of the three-phase winding stops outputting current to the power battery.

6. The powertrain according to claim 4, characterized in that, The powertrain is used for: During the process of receiving DC power from the DC power supply to charge the power battery, the charging switch is turned on, controlling the three upper bridge arms and three lower bridge arms of the three-phase bridge arm to be turned on alternately, and the three-phase winding outputs current to the power battery through the charging switch. When the charging switch is turned off, the three upper arms and three lower arms of the three-phase bridge arm are disconnected, and the three-phase winding stops outputting current to the power battery.

7. The powertrain according to claim 6, characterized in that, The powertrain is specifically used for: When the current through the freewheeling diode exceeds a preset current threshold, the three upper and three lower arms of the three-phase bridge arm are disconnected.

8. The powertrain according to claim 6, characterized in that, The powertrain is specifically used for: When the voltage to ground at the neutral point of the three-phase winding is greater than a preset voltage threshold, the three upper arms and three lower arms of the three-phase bridge arm are disconnected.

9. The powertrain according to any one of claims 4-8, characterized in that, The powertrain is specifically used for: During the process of the powertrain stepping down and charging the power battery, when the three upper arms of the three-phase bridge arm are turned on, the DC power supply charges the three-phase winding and the power battery; when the three lower arms of the three-phase bridge arm are turned on, the three-phase winding charges the power battery. When the charging switch is turned off, the three-phase winding is used to discharge to the bus capacitor through the freewheeling diode and the three upper bridge arms or the three lower bridge arms.

10. The powertrain according to any one of claims 1-9, characterized in that, At least one end of each phase arm of the three-phase power module is used to connect to the positive or negative terminal of the power battery via a first switch. At least one end of each phase arm of the three-phase bridge arm is used to connect to the positive or negative terminal of the DC power supply via a second switch.

11. The powertrain according to claim 10, characterized in that, During the process of the powertrain receiving power from the power battery to drive the electric vehicle, the first switch is turned on, the second switch is turned off, and the charging switch is turned off. During the process of the powertrain receiving power from the DC power source to charge the power battery, the first switch, the second switch, and the charging switch are all turned on.

12. A motor controller for DC charging compatibility, characterized in that, The motor controller is used to control the drive motor of the electric vehicle using power from the vehicle's power battery and to charge the vehicle's power battery using DC power. The motor controller includes a housing that houses a bus capacitor, a three-phase power module, and a freewheeling diode. The bus capacitor receives power from the power battery and outputs DC power to the three-phase power module. The motor controller housing is used to fix two first copper busbars, three second copper busbars, and one third copper busbar, wherein: The two first copper busbars are used to electrically connect the positive and negative terminals of at least one of the power battery or the DC power supply to the DC terminals of the three-phase power module; The three second copper busbars are respectively used to electrically connect the three-phase AC terminals of the three-phase power module and the three-phase windings of the drive motor; One end of the third copper busbar is used to electrically connect to the neutral point of the three-phase winding of the drive motor, and the other end of the third copper busbar is used to electrically connect to the negative terminal of the freewheeling diode. The positive terminal of the freewheeling diode is used to electrically connect to the DC terminal of the three-phase power module. The freewheeling diode is used to forward conduct the electrical connection between the neutral point of the three-phase winding and at least one DC input terminal of the power module.

13. The motor controller according to claim 12, characterized in that, During the process of the powertrain receiving current from the DC power supply to charge the power battery, if the powertrain malfunctions, the switching transistors of the three-phase bridge arms of the three-phase power module are all turned off, and at least one phase of the three-phase bridge arm of the three-phase power module, the freewheeling diode, the three-phase winding of the drive motor, and the bus capacitor form a discharge circuit.

14. An electric vehicle, characterized in that, The electric vehicle includes a power battery, a first switch, a second switch, and a powertrain as described in any one of claims 1-11. The first switch is used to connect or disconnect the connection between at least one end of each phase arm of the three-phase bridge arm and the power battery. The second switch is used to connect or disconnect the connection between the DC power supply and at least one end of each phase arm of the three-phase bridge arm, wherein: The powertrain is used to receive power from the power battery via the first switch to drive the electric vehicle; The powertrain is used to receive power from the DC power source via the second switch and reduce the voltage of the DC power output by the DC power source to charge the power battery.

15. The electric vehicle according to claim 14, characterized in that, During the process of the powertrain receiving power from the power battery to drive the electric vehicle, the first switch is turned on, the second switch is turned off, and the charging switch is turned off. During the process of the powertrain receiving power from the DC power source to charge the power battery, the first switch, the second switch, and the charging switch are all turned on.

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