A modified synchronous current regulator for field-oriented control of permanent magnet synchronous motors

This paper presents a modified synchronous current regulator for permanent magnet synchronous motors (PMSMs) with improved transient torque response and computational efficiency. PMSMs enable high power-density propulsion systems for electric and hybrid-electric vehicles. To satisfy the requirements of vehicle traction applications, the PMSM must be coupled with a robust, high-bandwidth torque controller, such as a synchronous (field-oriented) current regulator. In our modified synchronous current regulator, controller outputs are voltage magnitude and phase, rather than quadrature- and direct-axis voltage. The modified synchronous current regulator exhibits better transient response to torque commands due to inherent decoupling of the quadrature- and direct-axis control loops, without speed- or inductance-dependent decoupling paths. Since it does not use an inverse Park transform to create three-phase voltage signals, the control loop computational requirement is significantly reduced. We have implemented the modified synchronous current regulator on a PMSM-driven electric scooter with positive results.