Design of a Novel Underground Coal Mine 127V Power Supply
In view of the current disadvantages of the large size, high cost and low power factor of custom transformers in China's coal mine 127V power supply system, a novel type of unit power factor rectifier based on OCC (One Cycle Control) is proposed to supply the underground coal mine lighting system. The power supply consists of three stages, including a Vienna rectifier, a high frequency isolated DC DC converter and an inverter. However, the first two stages of the control circuit use a coordinated control. The circuit is simple to control, unit power factor operation can be realized without the multiplier and input voltage detection and half of the voltage stress of the switching device can be reduced as well. The paper analyses in detail the basic working principle and double closed loop control strategy of the new rectifier circuit. The correctness is fully verified by simulations.