A new model predictive control scheme, Optimized Switching Finite Control Set Model Predictive Control (OS-FCS-MPC), is studied in this paper for NPC single-phase three-level pulse width modulation (PWM) rectifiers. To ensure the actual stability of the power converter, the ac-side current error of single-phase PWM rectifier and the neutral point voltage of the converter are both converged to the bounded invariant set, and the adjustment of system performance is thus realized by setting the bounded invariant set. Based on the NPC single-phase three-level PWM rectifier model, the ac-side current, the neutral point voltage and the current error in the future time can be predicted in advance. The above objectives are achieved by optimizing the selection of switch combinations. The advantage of the proposed method is that it can reduce the average switching frequency of the converter when the ac-side current error and the neutral point voltage of the converter are controlled within a certain range, which makes it suitable for the application of high-power single-phase PWM rectifier.

A position sensorless control of interior permanent synchronous motor (IPMSM) equipped with LC sinusoidal filter based on the full-order sliding mode observer (FOSMO) and feedforward quadrature phase-locked loop (FQPLL) is proposed in this article. The FOSMO is designed to estimate stator currents, stator voltages, and extended back electromotive forces of IPMSM. To enhance the rapidity of the convergence and accuracy of the estimation of the FOSMO, an adaptive gain matrix is designed by adopting equivalent control theory and Lyapunov stability theory. In order to suppress the dc deviation in the position estimation error under acceleration or deceleration operations, a robust and anti-interference feedforward loop without differentiator and motor parameters is added to the conventional quadrature phase-locked loop. The parameter design method of the proposed FQPLL is studied by analysis of the frequency characteristics. The experimental results verify the effectiveness of the proposed strategy.

In traditional sensorless control of the interior permanent magnet synchronous motors (IPMSMs) for medium and high speed domains, a control strategy based on a sliding-mode observer (SMO) and phase-locked loop (PLL) is widely applied. A new strategy for IPMSM sensorless control based on an adaptive super-twisting sliding-mode observer and improved phase-locked loop is proposed in this paper. A super-twisting sliding-mode observer (STO) can eliminate the chattering problem without low-pass filters (LPFs), which is an effective method to obtain the estimated back electromotive forces (EMFs). However, the constant sliding-mode gains in STO may cause instability in the high speed domain and chattering in the low speed domain. The speed-related adaptive gains are proposed to achieve the accurate estimation of the observer in wide speed range and the corresponding stability is proved. When the speed of IPMSM is reversed, the traditional PLL will lose its accuracy, resulting in a position estimation error of 180°. The improved PLL based on a simple strategy for signal reconstruction of back EMF is proposed to ensure that the motor can realize the direction switching of speed stably. The proposed strategy is verified by experimental testing with a 60-kW IPMSM sensorless drive.

All-pass-filter-based single-phase phase-locked loop (APF-PLL) is a widely used grid synchronization method in grid-connected power converters. However, the performance of APF-PLL degrades under distorted grid conditions and the estimated phase and frequency will contain low-frequency oscillation terms, which is not conducive to practical application. To deal with this problem, this paper proposes two advanced APF-PLLs, which have good ability to suppress harmonics and dc offset interference without sacrificing the dynamic response of the system. In the first one, a band-pass filter (BPF) is used as the prefilter of APF-PLL to process the input voltage signal, and in the second one, the APF-PLL input signal is processed by using a harmonic decoupling network (HDN) and multiple prefilters. In addition, their parameter design procedure is also described in detail and is easy to follow. The experimental results presented in this paper finally verify the superiority and effectiveness of the two proposed methods.

This paper reports the optimal control problem on the interior permanent magnet synchronous motor (IPMSM) systems. The control performance of the traditional model predictive control (MPC) controller is ruined due to the parameter uncertainty and mismatching. In order to solve the problem that the MPC algorithm has a large dependence on system parameters, a method which integrates MPC control method and parameter identification for IPMSM is proposed. In this method, the d-q axis inductances and rotor permanent magnet flux of IPMSM motor are identified by the Adaline neural network algorithm, and then, the identification results are applied to the predictive controller and maximum torque per ampere (MTPA) module. The experimental results show that the optimized MPC control proposed in this paper has a good steady state and robust performance.

In single‐phase power and energy applications, sliding discrete Fourier transform (SDFT) filter based quadrature signal generation is a well‐known tool for designing advanced phase‐locked loops (PLLs), particularly for applications where high disturbance rejection ability is demanded. The SDFT‐based PLL, nevertheless, has a limited ability in achieving fast response (a response time more than one cycle of the nominal frequency). To deal with this problem, a synchronous reference frame PLL based on half‐cycle DFT (HCDFT) is proposed, enabling a fast and accurate synchronisation even in distorted grid. In this study, the fundamental voltage of the PLL input signal is obtained by a HCDFT filter. Then, phase, frequency and amplitude can be detected by the improved synchronous reference frame phase‐locked loop (SRF‐PLL). Besides, in order to solve the phase error when the frequency changes, a phase compensator is used. The HCDFT‐based SRF‐PLL method proposed in this study is compared, through experimental results, with a number of conventional methods, showing that the phase can be estimated under grid voltage disturbances accurately and quickly, which verifies the effectiveness and superiority of the proposed algorithm.