Development of Motor Controller for China Electric Forklift
In recent years, electric forklifts in China and other countries in the world have developed rapidly. The main part of an electric forklift is the electrical system, including electric control, motor and forklift traction battery. The drive system of an electric forklift generally consists of a motor, a control system, and a mechanical transmission device. At present, the driving motors selected for electric forklifts mainly include four types: DC motors, AC motors, permanent magnet synchronous motors, and switched reluctance motors.
The development of motor controller has mainly gone through the following stages:
(1) The battery starts directly, relying only on complicated adjustments or battery discharge control.
(2) The resistor starts. The control energy loss is large, and the speed can only be limited.
(3) Thyristor controller (also called thyristor controller) control. Transistor control greatly improves reliability. (4) Bipolar transistor control. Compared with the thyristor, it is easier to use, but the reliability of the circuit is relatively high.
(5) MOS field effect tube (ie metal-oxide-semiconductor field effect tube) control. The gate drive current is small, the parallel control characteristics are good, the forward voltage drop is small, and the switching loss is reduced. The MOS field effect tube has better control characteristics than the bipolar transistor. As the components are reduced and the fully enclosed device is adopted, the reliability is greatly improved.
Usually the socket voltage of SCR (silicon controlled silicon) controller is 1~1.5V, and the socket voltage of MOS field effect tube controller is 0.25V. MOS tube field effect tube has higher working efficiency, higher allowable maximum speed, lower operating noise and stronger protection measures.
And has three unique safety protection measures, namely software automatic protection measures, hardware automatic protection and hardware self-diagnosis protection. The successful application of the transistor chopper in the forklift not only realizes stepless speed regulation and regenerative braking, but also adds self-diagnosis and LCD digital display functions.
China's electric forklifts are developing rapidly, but the key technology of electric forklifts still has a certain gap compared with famous foreign electric forklift companies. Among them, the electric control part of the electric forklift has the largest lifting space.
