Inverter Nonlinearity Compensation Through Deadtime Effect Estimation

This article proposes a method to compensate for the nonlinearity of an inverter through the estimation of the deadtime effect. The deadtime effect varies with the manufacturing tolerance of the inverter circuit itself and operating conditions, such as conducting current, dc-link voltage, and temperature. For the accurate compensation of the nonlinearity, the effect of the deadtime should be estimated in realtime. That effect on the control of the inverter is significantly affected by the pulsewidth modulation (PWM) scheme because the deadtime occurs only at the switching instant of the inverter, and the PWM scheme solely decides the switching. The proposed method exploits the difference of voltage error from the deadtime effect according to different PWM schemes. By comparing the effects with two different PWM schemes, namely continuous PWM and discontinuous PWM, the voltage error to a specific inverter caused by the deadtime can be identified. Several experimental tests are carried out to verify the validity of the proposed method. The results reveal that the voltage error due to the deadtime can be identified in the range of 100 mV at 300-V dc link. It is equivalent to 30 ns resolution in deadtime.