Control Scheme For Inhibiting Inverter Harmonic Current In Five-Phase Induction Motor

Research in the area of multiphase machines has received ever-increasing concern over the past decade. When compared to the three-phase equivalents, the multiphase equivalents combines the advantages such as lower torque ripple, higher power density, higher efficiency, fault-tolerant operation, and can work out large power with low voltage. The newest developments in application of marine electric propulsion, electric vehicles (EVs) and hybrid electric vehicles (HEVs), more electric aircraft, locomotive traction. These are predominantly related to the possibility of reduction of the converter per-phase rating for the given machine power and to significantly improved fault tolerance.Based on the three-phase induction motor vector control system, according to the mathematical model established, in theory, five-phase induction motor vector control system can achieve a similar three-phase induction motor vector control system's requirements. It is shown that the model of five-phase induction motor is consistent with three-phase induction motor in the synchronous rotating d-q frame. It is the basis that Five-phase induction motor vector control can be modeled follow the three-phase vector control.This thesis introduced the five-phase PWM modulation of five-phase system. A detailed analysis for the particularity of the dead time effect in the five-phase inverter power supply of five-phase system has given. Dead time effect could cause the system to produce the non-ideal low-order harmonics. It does not affect the system output torque, but will lead to a sharp increase in stator loss. In practice, multi-phase motor used in low power or high reliability for special occasions, which requiring high control performance effect and need a simple and practical solution.The model in synchronous rotating reference d-q coordinate was created by using the transformation matrix method. Then the vector control system of five-phase induction motor was created. Found that five-phase induction motor vector control system using the general current control strategy can not eliminate the undesirable low order harmonics. Based on the harmonic distribution of five-phase system, a inhibiting inverter harmonic current control strategy using two pairs of simultaneous current controller was proposed. Simulation shows that the method can inhibit the undesirable current harmonics which was caused by dead time effects. Therefore the five-phase induction motor vector control system could be supply with ideal sinusoidal current.