Abstract
Online magnetization current control is a critical concern of the variable-flux permanent magnet machine control. Increasing the magnetization speed benefits the machine system, which reduces manipulation losses and mechanical impact. Thus, this paper proposes an online trajectory prediction method that increases the DC-link voltage utilization, boosting the manipulation speed. The prediction method decouples the rotating voltage and the induction voltage in the machine model. The induction voltage is the source of di/dt, which influences the magnetization manipulation speed. The proposed method updates the maximum available induction voltage at every manipulation stage by excluding the rotating voltage from the DC-link voltage limitation. Based on the induction voltage, the magnetization current trajectory is predicted. The trajectory prediction is cooperated with a feed-forward current controller to increase the control dynamics. Verified by various experiments, the proposed method achieves fast manipulation speed with high control accuracy. Besides, the proposed method shows self-adaptive capabilities in variable-speed and variable-voltage conditions.
Highlights
Variable speed applications like electric vehicles require high-efficiency electric machine systems
Permanent magnet synchronous machines (PMSMs) are one of the major machine types being applied in the variable speed fields [1], [2]
The change in the PM flux causes induction voltage on d-axis, whose value cannot be neglected because the time span of a single magnetization manipulation is usually less than 100 ms
Summary
Variable speed applications like electric vehicles require high-efficiency electric machine systems. Linear magnetization current trajectory causes voltage peaks that limit the maximum manipulation speed. Sinusoidal current trajectories were implemented to reduce the voltage peaks, thereby increasing the manipulation speed. This paper will propose an online MS manipulation current trajectory prediction and current control method, increasing the voltage utilization during the MS manipulation. The method predicts different id magnetization trajectories according to the machine operating conditions, i.e., the DC-link voltage and the machine speed. The change in the PM flux causes induction voltage on d-axis, whose value cannot be neglected because the time span (dt) of a single magnetization manipulation is usually less than 100 ms. Considering the influences from machine nonlinearity, the inductance value varies during the magnetization manipulations, so that the induction voltages and the rotating voltages are expressed with the flux linkage. Flux in the excitation stage and the recover stage shows different behaviors
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