Wang Gaolin

A novel design method for adaptive full order observer feedback matrix and speed estimation algorithm

In past works, there are three design method for adaptive full order observer, which is used in speed sensorless induction motor drives. That includes poles placement of observer, zero placement of speed estimation transfer function and error between estimated and actual rotor flux with motor parameters deviations. In this paper, the three available design strategy are analyzed. A novel speed estimation algorithm is proposed. The influence of proposed speed estimation algorithm on system stability is analyzed with or without observers feedback gains. The improvement of system robustness is analyzed. At last the feasibility of proposed method is verified by experiments.

Active flux based full-order discrete-time sliding mode observer for position sensorless IPMSM drives

To improve the control performance of the position sensorless interior permanent magnet synchronous motor (IPMSM) drives, an active flux model based full-order discrete-time sliding mode observer (DT-SMO) is proposed. Bearing in mind the modeling uncertainties and external disturbances, the observer design and the stability analysis are given. To reduce the inherent chattering problem of the sliding mode control, the sigmoid function is used. To enhance the position estimation accuracy, the quadrature phase-locked loop (PLL) is adopted to track the position information form the equivalent back electromotive force (EMF) obtained through DT-SMO. Experiments on a 2.2kW sensorless IPMSM vector controlled drive have been carried out to verify the proposed scheme.

EMF-based position sensorless control of IPMSM with improved current vector control strategy

This paper studies the sensorless interior permanent magnet synchronous motor (IPMSM) vector control strategy which is based on the EMF sliding-mode observer. As parameters selected for the position observer are obtained mostly by experimental adjustment, a phase locked loop (PLL) parameters design method based on the expected position estimation error is present. To improve the operation efficiency, a maximum torque per ampere (MTPA) control strategy based on current vector angle online tuning is introduced. In this way, the robustness against the motor parameters variations can be enhanced. The main idea is changing the reference of the stator current vector angle by a small value change, and then comparing the corresponding current value to tracking the ideal MTPA trajectory. The experiments on a 2.2kW IPMSM sensorless vector control system verifies the effectiveness of the PLL parameter design method and the MTPA control strategy.

Accurate inverter error compensation using self-tuning stator current estimation error in sensorless induction motor drives

Speed sensorless vector controlled induction motor drives have become very popular for motion-control applications due to their robustness. The performance of flux and speed observer is strongly influenced by the deadtime and inverter non-linear error at the low speed range. In most applications, the effect of deadtime can be offset by compensating the pulsewidth of PWM signal. However, the inverter non-linear error, such as voltage drop in switching devices, is difficult to compensate when the reconstructed phase voltage is utilized as the input of the observer, because it is not a fixed value. To solve the problem, in this paper the effect of non-linear error upon stator current estimation error is analyzed. A novel compensation method of non-linear error through the stator current estimation error is proposed. The proposed method separated the compensation of non-linear error from the deadtime compensation. Furthermore the nonlinear error can be identified directly off-line by the self-tuning method at the drive start-up and stored in the look-up-table. The experimental results demonstrate the feasibility of proposed method especially in the low speed range.

Rotor position estimation with full-order sliding- mode observer for sensorless IPMSM

In order to improve the rotor position estimation performance of position sensorless interior permanent magnet synchronous motor (IPMSM) control system in the dynamic situation, a full-order sliding-mode observer (SMO), of which the state variables were current and extended electromotive force (EEMF), was analyzed in this paper. Then, based on the EEMF model of IPMSM, a full-order state equation in the stationary reference frame was established. On the basis of Lyapunov analysis, a simplified method of designing the feedback gain matrix was presented. And the relationship between the parameters of the feedback-gain matrix and the dynamic response performance was studied specially. Experimental results demonstrated the feasibility of the full-order SMO with a position sensorless IPMSM control system.

Modified fiber-optic serial communication for cascaded multilevel converters

This paper proposed a novel automatic synchronization and multiple serial transfer clock frequency method (AS&MSC) for the fiber optic communication that is appropriate to cascade converters with better bit error rate performance. Comparing with conventional method, this method could automatically synchronize the transmitter and receiver without clock signals. Furthermore, the receiver could obtain the serial data with high resolution because of the multiple transfer clock. This paper also illustrated the FPGA implementation of this method, and the experimental results display that the proposed method has excellent performance to eliminate the transmission errors.

Current control for unbalance capacitors voltage STATCOM

Static compensation (STATCOM) gets more popular as the flexible AC transmission (FACTS) devices increase. The transformerless STATCOM has low cost and concentrates the research interests, however, the capacitors voltage unbalance problem will deteriorate its performance with more harmonics and over current/voltage faults. This paper presented one current control strategy to solve this problem. Firstly, the conventional DC voltage and current loop are implemented with decoupled method to control the active and reactive power for the symmetry system. Secondly, with adjusting the voltage angle, the unbalance phase voltages are impaired. Thirdly, the PWM redundant states replacement method is adopted to avoid the unbalance capacitors voltage in each phase[4], and new current loop to fast the balance process is designed. The simulation results demonstrate that this strategy could suppress the unbalance voltage and provide practicable measures for STATCOM.