Compensation of Nonlinearity of Inverter through Estimation of Dead Time Effect

This paper proposes a method to compensate for the nonlinearity of an inverter through the estimation of the dead time effect of the inverter. The dead time effect varies with manufacturing tolerance of the inverter circuit itself and operating conditions such as conducting current, voltage, and temperature. And, for the accurate compensation of the nonlinearity, the effect of the dead time should be estimated in real-time. The effect to the control of the inverter has a strong dependency on PWM scheme because the dead time occurs only at the switching instant of the inverter, and the switching is solely decided by PWM scheme. The proposed method exploits the difference of dead time effect according to different PWM scheme. 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 dead time 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 dead time can be identified in the range of 100 mV at 300 V DC link. It is equivalent to 30 ns resolution in dead time.