First, the motor controller overview
According to GB/T 18488.1-2001 "Electric motor motor and its controller technical conditions" definition of the motor controller, the motor controller is the device that controls the energy transmission between the main traction power supply and the motor, is the external control signal interface circuit , motor control circuit and drive circuit.
As the main components of electric vehicles, motors, drives and motor controllers play an important role in the whole vehicle system of electric vehicles. The research in related fields has important theoretical and practical significance.
Second, the principle of the motor controller
The motor controller acts as the control center for the entire brake system. It consists of an inverter and a controller. The inverter receives the DC power delivered by the battery, and inverts into a three-phase AC to supply power to the automobile motor. The controller receives signals such as motor speed and feeds back to the meter. When braking or acceleration behavior occurs, the controller controls the frequency of the inverter to rise and fall, thereby achieving the purpose of acceleration or deceleration.
Third, the classification of motor controller
1. DC motor drive system
The motor controller generally adopts pulse width modulation (PWM) chopper control mode, and the control technology is simple, mature, and low in cost, but has the disadvantages of low efficiency and large volume.
2. AC induction motor drive system
The motor controller adopts the PWM method to realize the power conversion of the high-voltage DC to the three-phase AC, and adopts the frequency conversion speed regulation mode to realize the motor speed regulation. The vector control or the direct torque control strategy is adopted to realize the rapid response of the motor torque control.
3. AC permanent magnet motor drive system
The utility model comprises a sine wave permanent magnet synchronous motor drive system and a trapezoidal wave brushless DC motor drive system, wherein the sine wave permanent magnet synchronous motor controller adopts a PWM method to realize a power conversion of a high voltage direct current to a three-phase alternating current, and adopts a frequency conversion speed regulation manner to realize a motor tuning. Speed; trapezoidal brushless DC motor control usually uses "weak magnetic speed regulation" to achieve motor control. Because the sine wave permanent magnet synchronous motor drive system has low speed torque ripple and high speed and constant power zone speed regulation, it has better application prospect than the trapezoidal wave brushless DC motor moving system.
4. Switched reluctance motor drive system
The motor control of the switched reluctance motor drive system generally adopts a fuzzy sliding mode control method. At present, the motors used in pure electric vehicles are permanent magnet synchronous motors, and the AC permanent magnet motors are excited by rare earth permanent magnets. Compared with induction motors, there is no need for excitation circuits, which has high efficiency, high power density, high control precision, small torque ripple, etc. Features.
Fourth, the relevant terms of the electric controller
1. Rated power: Output power under rated conditions.
2. Peak power: The maximum output power allowed by the motor for the specified duration.
3. Rated speed: The speed of the motor at rated power.
4, the highest working speed: corresponding to the motor speed of the highest designed vehicle speed of electric vehicles.
5. Rated torque: The output torque of the motor at rated power and rated speed.
6. Peak torque: The maximum torque that the motor is allowed to output for a specified duration.
7. Overall efficiency of the motor and controller: The motor shaft output power is divided by the controller input power and multiplied by 100%.