Inveror原理（Inveror principle）.docVIP

Inveror原理（Inveror principle） Frequency converter is a power control device that transforms the power supply into another frequency by using the power semiconductor device. We now use the frequency converter mainly adopts cross - straight - to pay way (VVVF inverter or vector control frequency conversion), the power frequency ac power first through the rectifier converts dc power supply, and then to convert the dc power supply frequency, voltage control of the ac power supply electric motor. The frequency converter circuit is generally composed of rectification, intermediate dc link, inverter and control. The rectifying part is a three-phase bridge uncontrollable rectifier, the inverter is IGBT three-phase bridge inverter, and the output is PWM waveform, the intermediate dc link is filtered, dc energy storage and buffer reactive power. Frequency converter selection: When selecting the frequency converter, the following points should be determined: 1) the purpose of frequency conversion; Constant pressure control or constant flow control. 2) load type of inverter; Such as vane pump or volume pump, special attention to load performance curve, performance curve determines the method of the application. 3) matching of frequency converter and load; I. voltage matching; The rated voltage of the inverter corresponds to the rated voltage of the load. II. Current matching; Ordinary centrifugal pump, the rated current of the converter is in line with the rated current of the motor. For special load such as deep water pump, it is necessary to refer to the motor performance parameters to determine the current and overload capacity of the converter with the maximum current. III. Torque matching; This can happen in a constant torque load or with a deceleration device. 4) when using the inverter to drive the high speed motor, due to the small electric resistance of the high speed motor, the higher harmonic increase causes the output current value to increase. Therefore, the select