The control of the grid-side PWM converter in the back-to-back PWM converter has been investigated in the paper.

As rotor-side power changes frequently during variable-speed constant-frequent(VSCF) wind generation operating,which causes dc-bus voltage fluctuation,the dual PWM converters control strategy is researched.

As the interface between PMSG(Permanent Magnet Synchronous Generator) and grid,thenormal converter configurations of direct - drive wind power system with PMSG are analyzed, including the diode rectifier + inverter,the diode rectifier + DC/DC converter + inverter,and the back - to - back dual PWM converter.

Compared with conventional cycloconverters, dual PWM converters have better input and output performances, less harmonic currents and a wider frequency adjustment range.

It consists of a fuel cell,an isolated uni-directional converter,a bi-directional converter,an inverter and a battery.

Bi-directional converter implements bi-directional energy transfer in the system, so the core of energy management is effective control bi-directional converter.

Due to complemented operation of switches in bi-directional converter, traditional soft start method will give rise to large inverse inductor current from the output source at double sources application, and result in damage of converter.

For isolated-type symmetry half-bridge bidirectional converter with phase-shifted control,a simplified circuit under 4 modes using the primary windings of transformer as reference object is built.

Generalized method and steps to model a bidirectional converter derived from the switching function concept and the black-box method using Matlab/ Simulink are proposed.