In this study, a novel field-oriented control (FOC) algorithm was proposed in a 60° coordinate system for controlling the speed of permanent magnet synchronous motors. The FOC algorithm consists of several parts in which the reference currents and feedback currents are transformed into the representation form in a 60° coordinate system. Current regulators are typically used in a 60° coordinate system to directly obtain the reference voltage vector. The proposed FOC structure was established by incorporating the space vector pulse width modulation algorithm in a 60° coordinate system. The proposed FOC structure simplified the FOC algorithm and reduced its computational burden. The feasibility of the proposed method was verified through simulations and experiments.

In this paper, a predictor based linearization approach is presented to solve the local asymptotic stabilization (LAS) problem of time-invariant nonlinear systems with a large constant input delay. Under stabilizability and detectability of the linearized time-delay system, we prove that LAS is achievable by either predictor based state or output feedback controllers, which can be designed directly based on the linearization. The predictor based linearization technique developed in this research complements the work [1] and improves its result by removing the forward completeness condition and a number of technical requirements as well as by expanding the class of nonlinear systems with input delay to the general case. An example is given to demonstrate the application of the predictor based linearization technique.

The mathematical model of three-phase voltage source PWM rectifier is established in the dq rotating frame. Aiming at the highly coupled of the active and reactive current of three-phase PWM rectifier, a control system with double close-loops of voltage and current is proposed based on the synchronous rotating reference frame. A sliding-mode control algorithm for the out-voltage-loop is proposed, and the exact feedback linearization method is designed for the current loop. The whole system is simulated and experimented. The whole system has good robustness, and this control scheme can realize decoupled control of the three phase PWM rectifiers. The power factor of the system is kept at unity. The PWM rectifier has constant output voltage, and the whole system has good dynamic and static performance.

A passivity-based power control method is proposed for the three-phase three-level NPC rectifier in this paper. The decoupled control of active and reactive power of the three-level NPC rectifier in the dq reference frame can be realized by the proposed method. The neutral point voltage is controlled by adjusting the dwelling time of the small vectors. The proposed modeling and control strategy are verified by the simulation and experimental results based on a 10kW equipment.