Pulse width modulation ( PWM) drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array ( FPGA ). First, digital PWM...Pulse width modulation ( PWM) drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array ( FPGA ). First, digital PWM principles are discussed. The primary and secondary current characteristics are analyzed when the transformer is in both normal and magnetic bias conditions. Second, two digitalization methods are put forward after the research on PWM adjustment principles, which are based on the primary current feedback. Though the two methods could restrain magnetic bias, their realization is difficult. A new method is researched on double close-loops to overcome the above shortcomings, which uses the secondary current as the feedback signal and the primary current as the protection signal. Finally, the secondary current control made is discussed and realized. Welding experimental results show that the method has strong flexibility and adaptability, which can be used to realize the full digital welding power supply.展开更多
This paper presents the control ofa WECS (wind energy conversion system), equipped with a DFIG (doubly fed induction generator), for maximum power generation and power quality improvement simultaneously. The propo...This paper presents the control ofa WECS (wind energy conversion system), equipped with a DFIG (doubly fed induction generator), for maximum power generation and power quality improvement simultaneously. The proposed control algorithm is applied to a DFIG whose stator is directly connected to the grid and the rotor is connected to the grid through a back-to-back AC-DC-AC PWM (pulse width modulation) converter. The RSC (rotor side converter) is controlled in such a way to extract a maximum power, for a wide range of wind speed. The GSC (grid side converter) is controlled in order to filter harmonic currents of a nonlinear load coupled at the PCC (point of common coupling) and ensure smooth DC bus voltage. Simulation results show that the wind turbine can operate at its optimum energy for a wide range of wind speed and power quality improvement is achieved.展开更多
文摘Pulse width modulation ( PWM) drive control digitalization is the key for the full digital invert power supply. New ideas are proposed, which are based on field programmable gate array ( FPGA ). First, digital PWM principles are discussed. The primary and secondary current characteristics are analyzed when the transformer is in both normal and magnetic bias conditions. Second, two digitalization methods are put forward after the research on PWM adjustment principles, which are based on the primary current feedback. Though the two methods could restrain magnetic bias, their realization is difficult. A new method is researched on double close-loops to overcome the above shortcomings, which uses the secondary current as the feedback signal and the primary current as the protection signal. Finally, the secondary current control made is discussed and realized. Welding experimental results show that the method has strong flexibility and adaptability, which can be used to realize the full digital welding power supply.
文摘This paper presents the control ofa WECS (wind energy conversion system), equipped with a DFIG (doubly fed induction generator), for maximum power generation and power quality improvement simultaneously. The proposed control algorithm is applied to a DFIG whose stator is directly connected to the grid and the rotor is connected to the grid through a back-to-back AC-DC-AC PWM (pulse width modulation) converter. The RSC (rotor side converter) is controlled in such a way to extract a maximum power, for a wide range of wind speed. The GSC (grid side converter) is controlled in order to filter harmonic currents of a nonlinear load coupled at the PCC (point of common coupling) and ensure smooth DC bus voltage. Simulation results show that the wind turbine can operate at its optimum energy for a wide range of wind speed and power quality improvement is achieved.