A specific model predictive control (MPC) strategy is considered in this paper to improve transient and steady-state current control performance of permanent magnet synchronous machine drives at low values of switching to fundamental frequency ratio, being a typical design scenario for high-power systems and/or high-speed machines. Among the different MPC proposals that have been reported in literature in the last decade, which usually control the average current (as in standard PI-based systems), an original and promising approach can be found in some recent papers that consider controlling the actual phase current at each switching instant by selecting the application times of the 2-level inverter configurations (i.e., an optimal switching pattern) as a result of the optimization process involving a prediction mechanism. This paper considers this new approach, and some interesting and original developments are presented and validated with respect to former proposals. A closed-form solution to the optimization problem is proposed, resulting in a simpler and more efficient implementation and allowing deterministic execution times. The prediction model is considered in the rotating reference frame (RRF), allowing the control of salient rotor machines and differentiation of the weights (and control dynamics) between the two axes. Furthermore, a one-cycle delay is considered between the sampling instant and the control action update (application actuation of the optimal switching pattern), which allows for the implementation on low-cost control microcontrollers. The description of the proposed strategies and complete analytical developments are reported. Relevant simulation results are included, proving the effectiveness of the proposal and better performance with respect to a standard PI-based FOC de-coupling controller. Implementation hints and preliminary results are also reported.
Fixed-Switching Frequency Model Predictive Current Control of PMSM: Closed-Form Solution in the Rotating Reference Frame Suitable for Salient Machines
Calligaro S.;Petrella R.;
2024-01-01
Abstract
A specific model predictive control (MPC) strategy is considered in this paper to improve transient and steady-state current control performance of permanent magnet synchronous machine drives at low values of switching to fundamental frequency ratio, being a typical design scenario for high-power systems and/or high-speed machines. Among the different MPC proposals that have been reported in literature in the last decade, which usually control the average current (as in standard PI-based systems), an original and promising approach can be found in some recent papers that consider controlling the actual phase current at each switching instant by selecting the application times of the 2-level inverter configurations (i.e., an optimal switching pattern) as a result of the optimization process involving a prediction mechanism. This paper considers this new approach, and some interesting and original developments are presented and validated with respect to former proposals. A closed-form solution to the optimization problem is proposed, resulting in a simpler and more efficient implementation and allowing deterministic execution times. The prediction model is considered in the rotating reference frame (RRF), allowing the control of salient rotor machines and differentiation of the weights (and control dynamics) between the two axes. Furthermore, a one-cycle delay is considered between the sampling instant and the control action update (application actuation of the optimal switching pattern), which allows for the implementation on low-cost control microcontrollers. The description of the proposed strategies and complete analytical developments are reported. Relevant simulation results are included, proving the effectiveness of the proposal and better performance with respect to a standard PI-based FOC de-coupling controller. Implementation hints and preliminary results are also reported.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
