Quantization Noise Reduction Using Random Dither in Direct Torque Control of an Induction Motor

A direct torque control (DTC) induction motor drive is presented in this paper. Quantization errors of current and voltage measurements are simulated and considered. To reduce the average quantization error and other offset errors of current and voltage measurement and eliminating the increasing integrator errors, a random dither signal is added to the truncating analog to digital converter (ADC) outputs. In this method, the ADC mean error is reduced to zero and therefore, integrator output error is mitigated. The proposed quantization method can improve the digital converter result; thus, this method can decrease the current measurement result. Thus, the torque and flux rippleswere be decreased. The proposed dither injection method can be used in Digital signal processor (DSP) or FPGA implemented applications. Experimental results show the performance of the proposed method.