The decrease in frequency is completely in proportional to the lower voltage, so the DC resistance will not change due to the reduced AC impedance, which will result in the decrease of the torque at low speed. Therefore, when given V/f at low frequency, the output voltage should be improved so as to obtain a certain starting torque, which is called enhanced starting.
When the magnetic circuit of motor changes with the running frequency fX during speed regulation, it is very easy to make the magnetic circuit of the motor serious saturation, which will lead to serious distortion of waveform of exciting current to produce a high peak current. Therefore, the frequency and voltage must be changed in proportion to change the frequency and control the output voltage of the inverter, so that the magnetic flux of the motor must be kept to avoid the occurrence of weak magnetic and magnetic saturation.
Rectifying circuit, starting protection, filter circuit, inverter circuit.
V/F sine pulse width modulation mode, open loop vector control mode, closed-loop vector control mode and direct torque control mode converter.
Power consumption of the inverter is 3-4%.
Inverter is a power control device that transforms the power supply into another frequency by using the power of the power semiconductor device.
Electrolytic capacitors need to be replaced after 30,000~40,000 hours