Static (solid state) frequency converters convert AC electrical power of one frequency into AC electrical power of another frequency. To realize high efficiency, great manageability and energy saving in industrial induction motor related applications, it is necessary to adopt controllable frequency converter systems.
The power conversion process isolates the critical load from the normal mains disturbances and isolates the mains from load induced reflected harmonics affecting other loads connected to the input mains feeder. The rectifier converts AC power into DC to provide the necessary DC for continuously rated capacity of the inverter. IGBT semiconductor modules are used in PWM inverter and the control logic creates the precise sinusoidal output waveform with a very low harmonic content. Thyristor semiconductor modules are also used in rectifier for reliable operation.
The system consists of rectifier, inverter, output isolation transforme, controls and monitoring. The AC output of the inverter is connected to the critical load,