Improved Voltage Flux-Weakening Strategy of Permanent Magnet Synchronous Motor in High-Speed Operation

Abstract

This paper presents an improved voltage flux-weakening strategy of a permanent magnet synchronous motor (PMSM) in a high-speed operation. The speed control performance using voltage flux-weakening control is not affected by the motor parameters, so it is used in various motors for high-speed operations. In general, the voltage flux-weakening control uses voltage references to generate a flux axis current reference. However, there may be errors between the voltage reference and the actual voltage flowing into the motor. This causes an error in the current reference generation and reduces the efficiency of the inverter and motor due to the use of more current. In this paper, the problems that can occur due to voltage errors were analyzed through theoretical approaches and simulations, and improved voltage flux-weakening control to resolve these problems was presented. This method’s advantage is that the error between the voltage reference and the voltage applied to the motor can be minimized, and the target speed can be reached with minimum current. As a result, it was possible to increase the energy efficiency by reducing the amount of current flowing through the motor. The effect of the improved voltage-based flux-weakening control method was verified through simulations and experiments. As a result, the voltage errors were reduced by approximately 2.16% compared to the general method. Moreover, the current used in the field-weakening control region was reduced by up to 27.17% under the same torque condition.

Review of Flux-Weakening Algorithms to Extend the Speed Range in Electric Vehicle Applications With Permanent Magnet Synchronous Machines

“…Lee et al in [68] analyse the performance of the FW strategy during the overmodulation area, with modulation strategies other than SVPWM. This article analyses the consequences of the error committed during the overmodulation area between the voltage vector on the feedback path and the voltage applied to the electric machine.…”

A Review about Flux-Weakening Operating Limits and Control Techniques for Synchronous Motor Drives

“…Before moving towards FW operation of motors which implement flux controllers, it is worth mentioning another key research topic, i.e., the effective usage of the inverter DC-bus voltage [59,60]. In fact, when the motor operates at high speed, the inverter works close to its intrinsic voltage constraints.…”

Variable Incremental Controller of Permanent-Magnet Synchronous Motor for Voltage-Based Flux-Weakening Control

“…In this study, flux-weakening control is performed through the voltage feedback structure, as illustrated in Figure 1, and an incremental controller is utilized to control the voltage-type controlled variable with the reference (𝑖 * ) of the current component [28].…”

“…In this study, flux-weakening control is performed through the voltage feedback structure, as illustrated in Figure 1, and an incremental controller is utilized to control the voltage-type controlled variable with the reference (i * ds ) of the current component [28]. As illustrated in Figure 2, the target amount, controlled variable, sensed voltage, and current values adopted in voltage and current controllers are generally converted into units of p.u.…”

“…This method has the advantage of being robust against change factors because it does not adopt motor parameters. However, because feedback is formed between the reference voltage and voltage applied to the motor, a controller capable of minimizing error values is required [28][29][30].…”