Second, the drive motor system function
By driving the working state of the motor, you can understand the basic functions of the new energy vehicle drive system, and drive the working state of the motor according to the driver's wishes: when the D-stop accelerates, when the brake is decelerated, when the R-stop is reversed, and when the E-stop is driven, It's working process.
1, D gear acceleration
The driver hangs the D gear and steps on the accelerator pedal. At this time, the gear position information and acceleration information are transmitted to the vehicle controller VCU through the signal line. The VCU transmits the driver's operation intention to the drive motor controller MCU through the CAN line, and then drives. The motor controller MCU combines the information of the resolver sensor (rotor position), and then the three-phase alternating current is supplied to the stator of the permanent magnet synchronous motor, and the three-phase current generates a voltage drop across the resistance of the stator winding.
The rotating armature magnetomotive force generated by the three-phase alternating current and the established armature magnetic field cut the stator winding on one hand and generate an induced electromotive force in the stator winding; on the other hand, the rotor is dragged by the electromagnetic force to rotate in the forward direction at the synchronous speed. As the accelerator pedal stroke continues to increase, the six IGBT turn-on frequencies controlled by the motor controller increase, and the torque of the motor increases as the current increases, so that the maximum torque is basically at the start. As the motor speed increases, the power of the motor also increases, and the voltage increases.
In electric vehicles, it is generally required that the output power of the motor is kept constant, that is, the output power of the motor does not change with the increase of the rotational speed. This requires that the voltage remains constant as the motor speed increases, and the output characteristic curve of the permanent magnet synchronous motor is as shown in FIG. .
At the same time, the motor controller also senses the current power, current consumption and voltage of the motor through the current sensor and the voltage sensor, and transmits the information data to the instrument and the vehicle controller through the CAN network.
2, when the R block is reversed
When the driver hangs the R gear, the driver request signal is sent to the VCU, and then sent to the MCU through the CAN line. At this time, the MCU combines the current rotor position (revolution sensor) information, and changes the W\V\U power-on sequence by changing the IGBT module. In turn, the motor is reversed.
3. Energy recovery during braking
When the driver releases the accelerator pedal, the motor is still rotating due to inertia. The wheel speed is V wheel and the motor speed is V motor. The fixed gear ratio between the wheel and the motor is K. When the vehicle decelerates, the V wheel K<V When the motor is running, the motor is still the power source. As the motor speed decreases, when the V wheel K>V motor, the motor rotates due to the drag of the vehicle, and the drive motor becomes the generator.
The BMS can calculate the corresponding allowable maximum charging current according to parameters such as the battery charging characteristic curve (charging current, voltage curve and battery capacity) and the battery temperature. The MCU maintains the maximum charging current according to the battery, and by controlling the IGBT module, the "generator" stator coil rotating magnetic field angular velocity and the motor rotor angular velocity are maintained until the generating current does not exceed the maximum allowable charging current to adjust the current that the generator charges the battery, and this Also controls the deceleration of the vehicle, the specific process
