Current Balance Control for Symmetrical Multiphase Inverters

The current imbalance between stator phase windings could shorten the motor life and affect the drive performance, whereas in case of multiphase drive applications, there is not a general current balance control strategy that can apply to symmetrical inverters with any phase number m. Based on the generalized symmetrical component theory, this letter analyzed the values of relative symmetrical components of the multiphase systems in balanced and unbalanced cases. Then, developed from the conventional rotor-flux oriented control (RFOC), the current-balance RFOC is proposed to compensate the current imbalance for symmetrical m-phase inverters. Finally, the experimental results from the five-phase and nine-phase drive systems confirm the validity of the control strategy in eliminating current imbalance.