Research On Voltage Stabilised Dc Converter Of Permanent Magnet Direct Drive Power Generation

The permanent magnet direct drive variable speed constant frequency(VSCF) systems is characterized by high reliability and low cost due to lack of variable-speed device. So it has comprehensive application in wind power generation and vehicle shaft generator field.The system makes up of prime mover, permanent generator and power electronic device. As the speed of permanent generator which is dragged by the prime mover alters in wide range, the alternating current with variable frequency and amplitude of voltage need to be converted to constant by AC/DC and DC/AC converter.Aiming at the requirement of permanent magnet direct drive VSCF systems, a design project of high power and wide input DC/DC converter is presented in this paper. The converter and the three-phase diode rectifier and the inverter by steady-going dc-link voltage constitute the power electronic device which exports constant alternating current. By changing the mode of the non-isolated buck-boost circuit, the voltage stress and current stress of power devices can reduce greatly.When the permanent magnet generator works at low-speed zone, the amplitude of input voltage is low. So the circuit uses interleaving-control when it works at Boost mode. The current of every inductance can reduce, and the whole equipment will take less space. Power density will heighten accordingly. On the other hand, this strategy raise the frequency and reduce the amplitude of current ripple in order to restrain the fluctuation of output. The current of every parallel unit is controlled alone which insures current -averaging.a prototype which has 24kW is developed on the platform of DSP TMS320LF2407 chip. The result of experiments validate that the converter which is designed in this paper achieves the goal of specifications.