According to the switching mode of the inverter circuit, the electric forklift inverter is classified, and the inverter can be divided into three types: PAW control mode, PWM control mode and high carrier frequency PWM control mode.
①PAM control is the abbreviation of Pulse Amplitude Modulation control. It is a control method in which the amplitude of the output voltage (current) is controlled in the rectifier circuit part, and the output frequency of the electric stacker is controlled in the inverter circuit part. Because the switching frequency of the inverter circuit commutator device in the PAM-controlled inverter is the output frequency of the inverter, this is a synchronous adjustment method.
②PWM control is the abbreviation of Pulse Width Modulation control, which is a control method that simultaneously controls the amplitude and frequency of the output voltage (current) in the inverter circuit part of the electric forklift stacker. In this control method, the semiconductor switching components of the inverter circuit are switched on and off at a relatively high frequency, and the purpose of controlling the voltage (current) of the forklift truck is achieved by changing the width of the output pulse.
③High carrier frequency PWM control This control method is actually an improvement of the PWM control method in principle, and is a control method adopted to reduce the noise of the motor running. In this control method, the carrier frequency is raised above the frequency that can be heard by the ear (10-20KHz), so as to achieve the purpose of reducing the noise of the forklift motor. This control method is mainly used for low-noise inverters, and will also be the development direction of inverters in the future. Since this control method has high requirements on the switching speed of the commutator device, the commutator device used can only use semiconductor components such as IGBT and MOSFET with high switching speed. certain restrictions. However, with the development of power electronic technology, the capacity of converter components with higher switching speed will be larger and larger, so it is expected that more and more frequency converters will adopt this control method.
Both PWM control and high carrier frequency PWM control belong to the asynchronous speed regulation mode, that is, the output frequency of the inverter is not equal to the switching frequency of the commutation device of the inverter circuit.
