A high-voltage electric drive active discharge system and control method

Abstract

The present invention discloses a high-voltage electric drive active discharge system and control method, comprising a power battery, a vehicle controller, a motor driver, and a motor; the motor driver comprises a control module and a main circuit module controlled by the system, as well as a motor driver module temperature detection element and a three-phase current detection element; the control module is used to receive instructions from the vehicle controller, control the main circuit module to switch the DC high-voltage power supply on and off, and receive feedback signals from each detection element. After calculation and processing, the main circuit module adjusts the amplitude and phase of the motor driver output current; the power battery is connected to the motor through the main circuit module to provide a DC high-voltage power supply input; the motor is provided with a motor stator three-phase winding and a motor temperature detection element. The present invention integrates the active discharge circuit with the drive circuit, eliminating the need for an additional active discharge device, reducing system cost, being unrestricted by the reliability of discharge peripherals, and extending the system life.

Description

Technical Field

[0001] The present invention belongs to the technical field of special electric drive systems for engineering machinery, and more specifically, relates to a high-voltage electric drive active discharge system and a control method. Background Art

[0002] The high-voltage electric drive system provides high-voltage DC power from the power battery, which is then fed into the motor driver. The motor driver receives torque commands from the vehicle controller and controls the motor in a timely manner, thereby driving the vehicle. The high-voltage electric drive active discharge system, upon receiving a power-off command from the vehicle controller, controls the discharge current in a timely manner to rapidly discharge the vehicle's energy storage components, ensuring that the residual voltage after the vehicle is powered off reaches a safe level. With the gradual maturity of "three-electric" (Electric, Electric, and Power) technologies, the electrification of construction machinery is becoming a trend. Simultaneously, these technologies are moving towards higher voltages, which effectively improve system efficiency but also introduce numerous high-voltage safety issues. Relying solely on passive discharge cannot meet higher safety standards. Therefore, active discharge technology has been introduced, offering faster and safer discharge times. High-voltage electric drive systems achieve rapid discharge using a discharge device consisting of an external resistor and contactor on the DC side. However, this device has drawbacks such as bulk, short lifespan, limited control flexibility, and high cost. Therefore, reusing the electric drive main circuit, controlling the electric drive output current, and utilizing the motor windings to dissipate energy presents promising application prospects.

[0003] Existing high-voltage electric drive systems for construction machinery often use an external discharge device to dissipate the residual high-voltage energy after power-off in the form of heat. The discharge device consists of a resistor, a contactor, and a drive circuit. Upon receiving the power-off command, the motor driver activates the active discharge function, closing the contactor via the contactor drive circuit. The energy in the motor drive's internal support capacitor is passively dissipated in the discharge resistor. This method uses resistor selection to control the discharge current, and thus the discharge time. This method is simple to control, but the discharge current is passive and cannot be controlled in a timely manner. This reduces the stability of current control and makes the discharge time difficult to control. Furthermore, the external discharge device increases system cost and reduces service life.

[0004] Another approach uses a combined discharge and drive circuit to dissipate the remaining energy in the support capacitor in the motor stator windings, controlling the active discharge time by controlling the motor driver's discharge current amplitude. This active discharge technique, which combines the discharge and drive circuits, fails to consider the impact of the driver power module and motor temperatures on the discharge current, making it difficult to accurately control the discharge time. Furthermore, simply controlling the discharge current amplitude can cause the driver, a phase module, and the stator winding to overheat, resulting in an overtemperature fault and reduced system reliability. Summary of the Invention

[0005] The purpose of the present invention is to address the above shortcomings and provide a high-voltage electric drive active discharge system and control method, which integrates the active discharge circuit and the drive circuit, does not require additional active discharge devices, can reduce system costs, is not limited by the reliability of discharge resistors and contactors, and extends the service life of the system; according to the parameter changes caused by the use of the motor, the amplitude of the motor driver output current is dynamically adjusted to improve the accuracy of discharge time control.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A high-voltage electric drive active discharge system, including a power battery, a vehicle controller, a motor driver and a motor;

[0008] The motor driver includes a control module and a main circuit module controlled by it, as well as a temperature detection element and a three-phase current detection element of the motor driver module; the control module is used to receive instructions from the vehicle controller, control the main circuit module to turn on and off the DC high-voltage power supply, and receive feedback signals from each detection element. After calculation and processing, the main circuit module adjusts the amplitude and phase of the motor driver output current;

[0009] The power battery is connected to the motor through the main circuit module to provide DC high-voltage power input;

[0010] The motor is provided with a motor stator three-phase winding and a motor temperature detection element.

[0011] Furthermore, the main circuit module includes a main contactor and a three-phase full-bridge circuit in sequence; the main contactor is connected to the input end of the DC high-voltage power supply to perform high-voltage power on and off, and the three-phase full-bridge circuit is used to adjust the amplitude and phase of the three-phase output current of the motor driver.

[0012] Furthermore, the motor driver also includes a contactor drive module and a PWM drive module. The contactor drive module receives a control module signal to drive the main contactor to be on and off; the PWM drive module receives a control module signal to modulate the three-phase full-bridge circuit to adjust the amplitude and phase of the motor driver output current.

[0013] Furthermore, a support capacitor connected in parallel with the power battery is provided at the rear end of the main contactor for output filtering and voltage smoothing.

[0014] Furthermore, a passive discharge resistor is connected in parallel to the support capacitor for passively releasing the energy stored in the support capacitor after power is removed.

[0015] Furthermore, the temperature detection element of the motor driver module is a power module thermistor, which is arranged in the main circuit module of the motor driver.

[0016] Furthermore, the three-phase current detection element is a three-phase Hall, which is arranged on the output three-phase line of the motor driver.

[0017] Furthermore, the motor temperature detection element is an electrode temperature-sensitive resistor, which is arranged on the equivalent resistance of the three-phase winding of the motor stator.

[0018] The present invention also provides a control method for the above-mentioned high-voltage electric drive active discharge system, comprising the following steps:

[0019] The motor driver receives the power-off command from the vehicle controller.

[0020] Detecting the current speed of the motor, and disconnecting the main contactor in response to the current speed of the motor being lower than a limit value;

[0021] Detect the motor driver module temperature and motor temperature,

[0022] In response to the motor driver module temperature and the motor temperature not exceeding the threshold, the three-phase output current of the motor driver is detected in real time as current vector control feedback, and the amplitude set value of the motor driver output current and the three-phase current vector angle and angular velocity value of the motor driver are calculated;

[0023] Motor driver output current closed-loop control.

[0024] Furthermore, after the main contactor is disconnected, the voltages at the front and rear ends of the main contactor are detected. If the voltage difference is higher than a threshold, it is determined that the main contactor is in the disconnected state.

[0025] Furthermore, the motor driver calculates the given value of the three-phase current vector amplitude of the motor driver based on the voltage across the supporting capacitor, the motor driver module temperature, the motor temperature and the discharge time; and determines the three-phase current vector angle and angular velocity value of the motor driver based on the current rotor position of the motor, the motor driver module temperature and the motor temperature fluctuation value.

[0026] By adjusting the amplitude of the motor driver's output current, the power loaded on the three-phase stator winding can be changed. Changing the phase of the motor driver's output current allows the current to be switched arbitrarily in the three-phase winding coordinate system. During active discharge, the motor driver's output power remains unchanged. Under the premise of ensuring that the active discharge time meets the standard, the temperature rise of the motor driver's power module and the motor stator's three-phase winding is uniform, avoiding damage to the motor driver and motor due to local heat accumulation.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The high-voltage electric drive active discharge system of the present invention integrates the active discharge circuit and the drive circuit, does not require additional active discharge devices, can reduce system costs, is not limited by the reliability of external discharge devices, and extends the service life of the system.

[0029] The present invention dynamically adjusts the amplitude of the output current of the motor driver according to parameter changes caused by the use of the motor, thereby improving the accuracy of discharge time control.

[0030] The system of the present invention monitors the module temperature, motor temperature, motor rotor angle and speed of the motor driver in real time. By controlling the angle of the driver output current, the controller module and motor windings on the three-phase bridge arm are heated evenly, ensuring the safety and stability of the electric drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A system composition block diagram of a high-voltage electric drive active discharge system provided in Example 1;

[0032] Figure 2 This is a main circuit topology diagram of the high-voltage electric drive active discharge system described in Example 1;

[0033] Figure 3 This is a flow chart of the control method of the high-voltage electric drive active discharge system described in Example 2.

[0034] In the figure: 1-power battery, 2-vehicle controller, 3-motor driver, 31-main circuit module, 311-main contactor, 312-passive discharge resistor, 313-support capacitor, 314-three-phase full-bridge circuit, 315-power module thermistor, 316-three-phase Hall, 32-contactor drive module, 33-PWM drive module, 34-control module, 4-motor, 41-motor stator three-phase winding equivalent resistance, 42-motor thermistor. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and specific examples.

[0036] Example 1

[0037] like Figure 1 The high-voltage electric drive active discharge system shown includes a power battery 1, a vehicle controller 2, a motor driver 3, and a motor 4. The motor driver 3 primarily comprises a main circuit module 31, a contactor drive module 32, a PWM drive module 33, and a control module 34. The power battery 1 is connected to the motor 4 via the main circuit module 31, providing a DC high-voltage power input. The motor 4 is equipped with a three-phase stator winding and a motor temperature detection element. The control module 34 is configured to receive instructions from the vehicle controller 2, control the contactor drive module 32 to drive the main circuit module 31 to turn the DC high-voltage power on and off, and receive feedback signals from various detection elements. After calculation and processing, it then drives the main circuit module 31 via the PWM drive module 33 to adjust the amplitude and phase of the output current of the motor driver 3.

[0038] The high-voltage electric drive active discharge system described in this embodiment has a main circuit topology consisting of a DC high-voltage power supply input, a main circuit module 31 of a motor driver 3, and an equivalent resistance 41 of a three-phase winding of a motor stator. Figure 2 The main circuit module 31 includes a main contactor 311 , a passive discharge resistor 312 , a support capacitor 313 , a three-phase full-bridge circuit 314 , a power module thermistor 315 and a three-phase Hall 316 .

[0039] The main contactor 311 is connected to the DC high-voltage input (power battery 1) and primarily powers the high voltage on and off. Upon receiving a power-off command from the vehicle controller 2, the motor driver 3 disconnects the main contactor 311, removing the DC high-voltage input from the system's main circuit. The DC high voltage is then input to the three-phase full-bridge circuit 314 via the main contactor 311. This three-phase full-bridge circuit 314, acting as a power electronic converter, modulates the current through the PWM drive module 33 to control the amplitude and phase of the current in the motor driver 3, thereby varying the power applied to the equivalent resistor 41 of the motor's three-phase stator windings. The support capacitor 313, connected in parallel with the high-voltage power supply at the rear end of the main contactor 311, primarily provides output filtering and smoothes the voltage input from the high-voltage power supply. The passive discharge resistor 312, connected in parallel with the support capacitor 313, passively and slowly releases the stored energy in the support capacitor 313 after power is removed.

[0040] The power module thermistor 315 is provided in the main circuit module 311 and serves as a temperature detection element of the motor driver module, and is used to measure the module temperature of the motor driver 3 in real time.

[0041] The three-phase Hall 316 is provided on the output three-phase line of the motor driver 3 as a three-phase current detection element for detecting the three-phase output current of the motor driver 3 in real time.

[0042] The motor temperature detection element is a motor thermistor 42 , which is arranged on the motor stator three-phase winding equivalent resistor 41 and is used to detect the temperature of the motor 4 in real time.

[0043] In the high-voltage electric drive active discharge system described in this embodiment, after the motor driver 3 receives the power-off command issued by the vehicle controller 2, the main contactor 311 is disconnected; at this time, the motor driver 3 controls the three-phase full-bridge circuit 314 through pulse modulation according to the current motor rotor position, the module temperature of the motor driver, the temperature of the motor stator winding, the real-time current of the motor three-phase and the active discharge time requirement, thereby controlling the amplitude and phase of the three-phase output current of the motor driver 3; the magnitude of the current amplitude can change the power loaded on the three-phase stator winding of the motor, and the change of the phase can make the current switch arbitrarily in the three-phase winding coordinate system; during the active discharge process, the output power of the motor driver 3 remains unchanged, and on the premise of ensuring that the active discharge time meets the standard, the temperature rise of the motor driver power module and the motor stator three-phase winding is uniform, thereby avoiding damage to the motor driver 3 and the motor 4 due to local heat accumulation.

[0044] Example 2

[0045] This embodiment provides a control method for a high-voltage electric drive active discharge system. Based on the high-voltage electric drive active discharge system described in Example 1, the process is as follows: Figure 3 As shown, the following steps are included:

[0046] The motor driver 3 receives the power-off command from the vehicle controller 2.

[0047] Detecting the current speed of the motor 4, and disconnecting the main contactor 311 in response to the current speed of the motor 4 being lower than a limit value;

[0048] Detect the temperature of the motor driver 3 module and the motor 4 temperature,

[0049] If the temperature of the motor driver 3 module and the motor 4 exceeds the threshold, an over-temperature fault is reported and active discharge fails;

[0050] If the temperature of the motor driver 3 module and the temperature of the motor 4 do not exceed the threshold, the three-phase output current of the motor driver 3 is detected in real time as current vector control feedback;

[0051] Calculate the given value of the three-phase current vector amplitude of the motor driver 3 according to the voltage across the supporting capacitor 313, the temperature of the motor driver 3 module, the temperature of the motor 4 and the discharge time;

[0052] Determine the three-phase current vector angle and angular velocity value of the motor driver 3 according to the current rotor position of the motor 4, the module temperature of the motor driver 3 and the temperature fluctuation value of the motor 4;

[0053] The motor driver 3 outputs current closed-loop control.

[0054] In the above method, after the main contactor 311 is disconnected, the voltages at the front and rear ends of the main contactor 311 (i.e., the DC high voltage input value and the voltage value of the support capacitor 313) are detected. If the voltage difference is higher than a threshold, it is determined that the main contactor 311 is in the disconnected state.

[0055] While various embodiments of the present invention have been described above, the foregoing description is intended to be illustrative and non-exhaustive, and is not intended to be limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those skilled in the art without departing from the scope and technical principles of the described embodiments, and such modifications and variations should be considered within the scope of the present invention.

Claims

1. A high voltage electric drive active discharge system, characterized in that: Including power battery, vehicle controller, motor driver and motor; The motor driver includes a control module and a main circuit module controlled by it, as well as a temperature detection element and a three-phase current detection element of the motor driver module; the control module is used to receive instructions from the vehicle controller, control the main circuit module to turn on and off the DC high-voltage power supply, and receive feedback signals from each detection element. After calculation and processing, the main circuit module adjusts the amplitude and phase of the motor driver output current; The power battery is connected to the motor through the main circuit module to provide DC high-voltage power input; The motor is provided with a motor stator three-phase winding and a motor temperature detection element; The main circuit module includes a main contactor and a three-phase full-bridge circuit in sequence; the main contactor is connected to the input end of the DC high-voltage power supply to perform high-voltage power on and off, and the three-phase full-bridge circuit is used to adjust the amplitude and phase of the three-phase output current of the motor driver; The motor driver further comprises a contactor drive module and a PWM drive module, wherein the contactor drive module receives a signal from the control module and drives the main contactor to be turned on and off; The PWM drive module receives the control module signal, modulates the three-phase full-bridge circuit, and adjusts the amplitude and phase of the motor driver output current.

2. The high-voltage electric drive active discharge system according to claim 1, characterized in that: The rear end of the main contactor is provided with a support capacitor connected in parallel with the power battery for output filtering and voltage smoothing.

3. The high-voltage electric drive active discharge system according to claim 2, characterized in that: The support capacitor is connected in parallel with a passive discharge resistor for passively releasing the energy stored in the support capacitor after power is turned off.

4. The high-voltage electric drive active discharge system according to claim 1, characterized in that: The motor driver module temperature detection element is a power module thermistor, which is arranged in the main circuit module of the motor driver.

5. The high-voltage electric drive active discharge system according to claim 1, characterized in that: The three-phase current detection element is a three-phase Hall, which is arranged on the output three-phase line of the motor driver.

6. The high-voltage electric drive active discharge system according to claim 1, characterized in that: The motor temperature detection element is an electrode temperature-sensitive resistor, which is arranged on the equivalent resistance of the motor stator three-phase winding.

7. A control method for a high-voltage electric drive active discharge system according to any one of claims 1 to 6, characterized in that: The following steps are involved: The motor driver receives the power-off command from the vehicle controller. Detecting the current speed of the motor, and disconnecting the main contactor in response to the current speed of the motor being lower than a limit value; Detect the motor driver module temperature and motor temperature, In response to the motor driver module temperature and the motor temperature not exceeding the threshold, the three-phase output current of the motor driver is detected in real time as current vector control feedback, and the amplitude set value of the motor driver output current and the three-phase current vector angle and angular velocity value of the motor driver are calculated; Motor driver output current closed-loop control; The motor driver calculates the given value of the three-phase current vector amplitude of the motor driver according to the voltage across the supporting capacitor, the temperature of the motor driver module, the motor temperature and the discharge time; The motor driver determines the three-phase current vector angle and angular velocity values of the motor driver according to the current rotor position of the motor, the temperature of the motor driver module and the temperature fluctuation value of the motor.

8. The control method of the high-voltage electric drive active discharge system according to claim 7, characterized in that: After the main contactor is disconnected, the voltages at the front and rear ends of the main contactor are detected. If the voltage difference is higher than a threshold, it is determined that the main contactor is in a disconnected state.

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