Input Rectifier and Output Inverter

Input Rectifiers: From the three-phase power supply current of each phase first introduced. The introduction of non-sinusoidal current, and not as a standard AC sine wave, as the conversion process but in the rectifier distortion generated. Distortion means that the supply current waveform contains harmonics due to distortion of the waveform can be decomposed into a set of sinusoidal components, both people are talking about harmonics. As the power supply is a standard symmetrical three-phase power, while the rectifier is a part of the open-loop is not controllable, so the harmonics of the "second" number is certain, so harmonics generated by rectifier part of the very few.

The output inverter: DC flowing through the filter capacitor filter and high-power IGBT inverter transistor switching elements for the exchange of variable frequency voltage. In the inverter output circuit, the output current is modulated by the PWM carrier signal pulse shape, high-power inverter for the GTR components, and its PWM carrier frequency of 2 ~ 3kHz, while the IGBT inverter high-power components, the maximum PWM carrier frequency can be up to 15kHz. Similarly, the output loop current of sine wave can be decomposed into only with the fundamental and other harmonics, the main harmonic frequency for the first time (fundamental, 50Hz), the fifth harmonic (250Hz) the seventh harmonic wave (350Hz), the 11th harmonic (550Hz), the 13th harmonic (650Hz). We are working mechanism from the inverter can be seenInverterMost of the harmonics and interference are generated in the inverter, the high-order harmonic current of load there is a direct interference (when the role of the motor when the motor manifestations were fever, sound ugly. When the role of analog devices when the , meter pointer and readings bounce, these phenomena are subject to interference phenomena), the other high-order harmonic currents through the cable to the space radiation can interfere with nearby electrical equipment.