Cost-effective design of an inverter output reactor in ASD applications

In this paper, the cost-effective design of an output reactor which is used to suppress the overvoltage at the motor terminal in the adjustable speed drives (ASD) application is proposed. In the elevator drive system, the power cable length is relatively shorter than other ASD applications and then the overvoltage at the motor terminal depends on the frequency characteristics of the output reactor at the overvoltage operating frequency. The overvoltage suppression mechanism of the output reactor in ASD application is analyzed and the dominant parameters of the output reactor for the overvoltage suppression are extracted. Using these parameters as the design values and considering the high frequency characteristics of the iron core in the reactor, a new cost-effective structure of output reactor is proposed. Experimental results of the conventional reactor and the proposed reactor with a 15 kW induction motor are given to verify the proposed scheme.