Speed Control Of Electric Vehicle

The motor speed control device is set for the speed change and direction change of electric vehicles. Its function is to control the voltage or current of the motor and complete the control of the driving torque and rotation direction of the motor.
In the early electric vehicles, the speed regulation of DC motor was realized by connecting resistance in series or changing the number of turns of motor field coil. Because its speed regulation is stepwise and will generate additional energy consumption or the structure of the motor is complex, it is rarely used now. Thyristor chopper speed regulation is widely used to realize stepless speed regulation of the motor by uniformly changing the terminal voltage of the motor and controlling the current of the motor. With the continuous development of electronic power technology, it is also gradually replaced by other power transistors (such as GTO, MOSFET, BTR and IGBT) chopper speed regulation devices. From the perspective of technology development, with the application of new drive motors, it will become an inevitable trend that the speed control of electric vehicles will be transformed into the application of DC inverter technology.
In the control of the rotation direction change of the drive motor, the DC motor depends on the contactor to change the current direction of the armature or magnetic field to realize the rotation direction change of the motor, which makes the circuit complex and reduces the reliability. When the AC asynchronous motor is used for driving, the change of motor rotation can only change the phase sequence of the three-phase current of the magnetic field, which can simplify the control circuit. In addition, the use of AC motor and its variable frequency speed control technology makes the braking energy recovery control of electric vehicles more convenient and the control circuit simpler.