company news

Classification of frequency converters.

1. Classification according to working principle

(1) V/F control inverter

It is a control method of the frequency converter that is below the reference frequency. The output voltage of the frequency converter is proportional to the output frequency. A control method of outputting constant torque is the most basic control method of the frequency converter.

(2) Vector control inverter

It decomposes the stator current vector of an asynchronous motor into a current component that generates a magnetic field (excitation current) and a current component that generates torque (torque current), which are controlled separately, and the amplitude and phase between the two components are controlled at the same time, that is, the stator is controlled. Current vector, so this control method is called vector control method.

2. Classification according to the properties of DC power supply

(1) Current type inverter

The characteristic of current-type inverters is that a large inductor is used in the middle DC link as an energy storage link to buffer reactive power, that is, to suppress changes in current and make the voltage close to a sine wave. Because the DC internal resistance is large, it is called a current-source inverter ( current type). The characteristic (advantage) of the current-type inverter is that it can suppress frequent and sharp changes in the load current. It is often used in situations where the load current changes greatly.

(2) Voltage type inverter

The characteristic of the voltage-type inverter is that the energy storage element in the intermediate DC link uses a large capacitor, and the reactive power of the load will be buffered by it. The DC voltage is relatively stable, and the internal resistance of the DC power supply is small, which is equivalent to a voltage source, so it is called a voltage-type inverter. It is often used in situations where the load voltage changes greatly.