The brushless DC motor(BLDCM)with trapezoidal electromotive force(back-EMF)waveform is used widely.In principle,when the motor runs in the 120°conduction mode,two of the three phases are active while the other ph...The brushless DC motor(BLDCM)with trapezoidal electromotive force(back-EMF)waveform is used widely.In principle,when the motor runs in the 120°conduction mode,two of the three phases are active while the other phase is inactive at all times.However,a ripple current occurs in the inactive phase due to the diode freewheeling during the non-commutation period in the traditional pulse width modulation(PWM)methods,which aggravates the torque ripples.A new PWM method is proposed in this paper to eliminate the diode freewheeling during the non-commutation period in the inactive phase.As a result,the torque ripple is suppressed using the proposed method.The simulation and experimental results are demonstrated to verify the validity of the proposed PWM method.展开更多
A novel three-level zero-voltage zero-current switching(ZVZCS)DC/DC converter is proposed in this paper.A tapped-inductor is used to replace the normal out-put filter inductor,so that the circulating current in the ze...A novel three-level zero-voltage zero-current switching(ZVZCS)DC/DC converter is proposed in this paper.A tapped-inductor is used to replace the normal out-put filter inductor,so that the circulating current in the zero-state can be reset to zero.The reset voltage and the re-set time can be set conveniently just by simply changing the winding ratio of the tapped inductor.The converter achieves a zero-current tuning off for inner switching,and a zero-voltage tuning on for outer switching.No circulating current exists in the zero state,so that the loss in the on-state is reduced,and the efficiency can be improved.The experimental results verify that the ZVZCS has low voltage stress,zero-voltage and zero-current switching.展开更多
文摘The brushless DC motor(BLDCM)with trapezoidal electromotive force(back-EMF)waveform is used widely.In principle,when the motor runs in the 120°conduction mode,two of the three phases are active while the other phase is inactive at all times.However,a ripple current occurs in the inactive phase due to the diode freewheeling during the non-commutation period in the traditional pulse width modulation(PWM)methods,which aggravates the torque ripples.A new PWM method is proposed in this paper to eliminate the diode freewheeling during the non-commutation period in the inactive phase.As a result,the torque ripple is suppressed using the proposed method.The simulation and experimental results are demonstrated to verify the validity of the proposed PWM method.
文摘A novel three-level zero-voltage zero-current switching(ZVZCS)DC/DC converter is proposed in this paper.A tapped-inductor is used to replace the normal out-put filter inductor,so that the circulating current in the zero-state can be reset to zero.The reset voltage and the re-set time can be set conveniently just by simply changing the winding ratio of the tapped inductor.The converter achieves a zero-current tuning off for inner switching,and a zero-voltage tuning on for outer switching.No circulating current exists in the zero state,so that the loss in the on-state is reduced,and the efficiency can be improved.The experimental results verify that the ZVZCS has low voltage stress,zero-voltage and zero-current switching.
