The auxiliary PWM signal implementation of half DC-link inverter for long cable applications

In PWM three-phase inverter, the fast high voltage rises (dv/dt) of pulsed inverter voltage is the main cause of over-voltage problems, reducing lifetime of motor, in long cable applications. The typical passive filter to resolve this problem may be difficult to design for varying cable lengths. In this paper, the half dc-link inverter with improved auxiliary PWM generation is proposed to overcome the disadvantages of using passive filters. The correct the PWM duty cycle at motor terminals is also obtained at motor terminals. This is important to obtain the correct fundamental voltage at motor terminal, especially in low voltage operation (or torque boost region). The analysis, hardware design, simulation and experimental results of this improved auxiliary PWM signal implementation will be presented in this paper.