Mechanisms and modeling of regeneration in an inverter driven permanent magnet synchronous machine

The widespread use of permanent magnet synchronous machines (PMSMs) as prime movers in electromechanical actuators is well documented. Their operating conditions continue to become more complicated and dynamic as the applications become more diverse. Dynamic operating conditions can force the direction of power flow in the motor and drive portion of the system to reverse. This condition, called regeneration, is defined as any situation where the motor supplies power to the electronic drive, despite an applied terminal voltage. In this dissertation, operating conditions which cause regeneration will be defined. Regeneration due to switching behavior in the PWM controlled inverter is explored as well. The mechanisms of regeneration are also explained. A vector controlled method is used to linearize the control of the PMSM. The conventional technique of forcing the direct axis current to be zero is employed. The three-phase drive designed and constructed for this research is described in detail, and the control method used is explained. The traditional model of the PMSM used for control design is presented in the 0dq reference frame. A new model is the created by augmenting the traditional PMSM model with an equation describing the bus voltage variations due to regeneration. This new model is derived using a power flow analysis approach, and the experimental data support the accuracy of this model. Susceptibility of the model to variations in bus capacitance and equivalent parallel resistance are discussed in detail. Finally, suggestions for the improvement of this model are proposed and future research topics discussed.