Zhuang-Zhuang Xin

This paper proposes a novel two-switching-sequence pulse width modulation (TSSPWM) strategy to solve the current reconstruction dead zone (CRDZ) problem for single DC-link shunt permanent magnet synchronous motor (PMSM) drives. The switch conduction sequence and voltage vector synthesis principles of TSSPWM are first analyzed, which is different from the existing methods. TSSPWM contains measured voltage vectors and compensated voltage vectors in one switching period. It has symmetric PWM and mid-cycle current sampling structure. Based on the current error analysis, the phase currents reconstructed using this structure are close to the average current of a PWM cycle. Then, the implementation and CRDZ of TSSPWM are also provided. Since TSSPWM only applies one strategy to different CRDZs, it has the characteristics of small memory footprint and fast running speed. Finally, the experimental results demonstrate that the proposed method is lighter, faster and simpler than other methods under various operating conditions.

Three Hall-effect sensors can be used to estimate the continuous rotor position of permanent magnet synchronous motors (PMSM) with low cost. However, available position estimation methods generally require motor model parameters or have a phase offset. For this purpose, this paper proposes a harmonic-decomposition complex-coefficient filter-based phase-locked loop (HD-CCF-PLL) structure that is independent of motor parameters and has a near-zero phase offset. First, the triggering principle of Hall-effect sensors is introduced and the effect of Hall position error on current harmonics and torque ripples is analyzed. Then, coordinate transformation and harmonic decomposition methods are presented for three Hall-effect sensors. However, there is a limit to the number of times a microcontroller can perform real-time harmonic decomposition. The decomposed Hall position vector still contains high-order harmonics, which reduces position estimation accuracy. Therefore, an CCF-PLL technique is employed to filter out these harmonics and estimate the rotor position. An efficient method of CCF-PLL online parameter self-adjustment is also provided for adapting to different speeds. Finally, the effectiveness of the proposed method is verified by detailed experiments. The results show that the proposed method can effectively filter out the harmonics in the Hall position vector with higher position estimation accuracy, fewer current total current harmonic distortion, and smaller torque ripple than the existing method.

Model Predictive Control (MPC) based on Discrete Space Vector Modulation (DSVM) has the advantages of simple mathematical model and fast dynamic response. It is widely used in permanent magnet synchronous motor (PMSM). Additionally, the control performance of DSVM-MPC is influenced by the accuracy of motor parameters and the select speed of optimal voltage vector. In order to identify motor parameters accurately, model predictive control for PMSM based on discrete space vector modulation with recursive least squares (RLS) parameter identification is proposed in this paper. Additionally, a method to preselect candidate voltage vectors is proposed to select the optimal voltage vector more quickly. The simulation model of RLS-DSVM-MPC is established to simulate the influence of different parameters on PMSM performance. The simulation results show that model predictive control for PMSM based on discrete space vector modulation with RLS parameter identification has a better control performance than that of without RLS parameter identification.

As the extension of traditional linear (or X) inverted pendulum (IP), X-Z IP is a multiple-input multiple-output (MIMO), underactuated, open-loop unstable, and nonlinear system. In the tracking control of the X-Z IP, the equilibrium point changes with the pivot position of the pendulum. This makes linear control theories have difficulties in realization of the tracking control for the pendulum. The underactuated feature of the pendulum makes the feedback linearization unsuitable to simplify the control design. With the present model of the X-Z IP, there is no way to realize the backstepping design. This paper gives a novel state transformation method for the X-Z IP. Through the state transformation, the block backstepping can be easily deployed in the controller design of the X-Z IP. The proposed controller can achieve the tracking control in the vertical plane. Simulation results certify the rightness and effectiveness of the proposed tracking controller.