Frequency Inverter Tech

Modern Frequency inverters (see on our website: http://www.inverters.cn ) come in two major formats, V/Hz and vector. The V/Hz frequency inverter is a frequency inverter where the voltage applied to the motor is directly related to the frequency. In the ideal motor, the magnetic circuit would be purely inductive and keeping a constant V/Hz ratio would maintain a constant flux in the iron. The real motor has resistance in series with the magnetising inductance. This has no bearing on the operation at line frequency, however as the frequency of the frequency inverter is reduced, the resistance begins to become significant relative to the inductive reactance. This causes the flux to reduce at very low frequencies and so it is difficult to get sufficient torque at low speeds. For many applications, this low torque is not a problem, but there are some that do need a high torque from a low speed. Early frequency inverters were designed with a voltage boost to provide a measure of torque increase at low speed.