Tunnel fan to speed up the fan, use a frequency converter.The frequency converter is mainly composed of a rectifier, a filter, a frequency converter, a brake unit, a drive unit, and a microprocessor unit of the detection unit.The frequency converter transfers the voltage and frequency of the input power supply through the external IGBT, and needs the excess power supply voltage according to the practical needs of the fan, to complete the means of energy saving and progress transfer.

The generator protection circuit is formed and the secondary frequency converter of the tunnel fan needs the control signal of the main channel. Voltage/DC detection circuit for the main circuit, progress detection circuit for the generator, control circuit, converter and inverter for reducing the control signal of the arithmetic circuit.