SIMPLIFIED AND INNOVATIVE HYBRID RANDOM PWM ALGORITHM FOR DTC-INDUCTION MOTOR DRIVE FOR REDUCED NOISE

Abstract

A simple and novel hybrid random PWM algorithm for direct torque controlled induction motor drive for reduced noise and harmonic distortion is presented in this paper to reduce the complexity of the classical space vector approach, the proposed algorithm is developed by using the imaginary switching times, which does not require angle and sector information. In order to get the randomization effect, the proposed algorithm uses DPWMMAX algorithm in conjunction with the SVPWM algorithm. The harmonic analysis of the two switching sequences is carried out and by comparing each other in each sampling time interval, the proposed algorithm selects a suitable switching sequence that results in reduced harmonic distortion. In the proposed algorithm by changing the factor , which is proportional to the time duration of zero voltage vector V0 (000) the switching sequences of SVPWM and DPWMMIN algorithms are generated. As the zero state time is varied randomly according to the operating sequence, randomization effect will occur, which results in reduced dominating harmonics and hence gives reduced acoustical noise. To validate the proposed PWM algorithm, the numerical simulation studies have been carried out and results are presented and compared. The simulation results confirm the effectiveness of the proposed algorithm.