Hu Yuwen

Control of a Novel Dual Stator-Winding Induction Generator for wide speed-range operation

A novel dual stator winding induction generator (DWIG) system with diode bridge which is suitable for a wide speed operation is presented in this paper. This generator with two set windings in the stator, one is used to supply the power to the diode bridge load, and the other is referred as the control winding, which is fed with the static excitation controller(SEC) to balance the reactive power. The instantaneous power theory is employed here to analyze the control mechanism when machine working in the variable speed mode. The SEC volume optimal strategy is proposed, and the simulation is used to find an optimal value of the capacitor bank based on a SEC volume optimal strategy. An 18 kW DWIG with a speed range of 4000 rpm 8000 rpm platform is setup, and the dSPACE is employed to establish the rapid control prototype. The typical performance of the system, such as the voltage buildup process, the voltage when the primary mover varies its speed and the step change of the load are shown with simulation and experimental.

Decoupling control of the dual stator-winding induction generator using SVM

A decoupling control strategy for the dual-stator winding induction generator (DWIG) system using space vector modulation (SVM) is described in this paper. The DWIG consists of a standard squirrel-cage rotor and a stator with two sets of 3-phase star-connected windings. The power winding feeds the load with DC voltage by the diode rectifier. The control-winding is fed from a static excitation controller (SEC), through which the output voltage of power-winding is regulated. Moreover, the control-winding can be designed for higher voltage than the power-winding to reduce the SEC current. It will help to reduce the power switch loss. The model of SEC is setup, based on which a de-coupler is introduced to get the fast control of d-q currents. The SVM is incorporated to produce the PWM signals. The nodal admittance method is presented to analyze the change rule of SEC during the wide- speed-range operation. An 18 kW DWIG system is provided to demonstrate the effectiveness and robustness of the proposed control strategy. dSPACE is employed to establish the rapid control prototype for the control strategy. Simulation and experimental results prove the effectiveness and good performance of DWIG system under the proposed control strategy.

Research on a direct torque control for an electrically excited synchronous motor drive with low ripple in flux and torque

The electrically excited synchronous motor (ESM) has typically small synchronous inductance values and quite low transient values because of the damper windings mounted on the rotor. Therefore, the torque and stator flux linkage ripples are high in the direct torque control (DTC) drive of the ESM with a torque and flux linkage hysteresis controller (basic DTC). A DTC scheme with space vector modulation (SVM) for the ESM was investigated in this paper. It is based on the compensation of the stator flux linkage vector error using the space vector modulation in order to decrease the torque and flux linkage ripples and produce fixed switching frequency under the principle that the torque is controlled by the torque angle in the ESM. Compared with the basic DTC, the results of the simulation and experiment show that the torque and flux linkage ripples are reduced, the maximum current value is decreased during the startup, and the current distortion is much smaller in the steady-state under the SVM-DTC. The field-weakening control is incorporated with the SVM-DTC successfully.

Optimal design of dual stator-winding induction generator with variable speed based on improved genetic algorithm

The idea of applying the novel dual stator-winding induction generator based on PWM converter to aviation, tank and automobile supply is presented. The minimization to converters reactive power of control winding is the key to optimization of the system. The determination of excited capacitors to minimize the reactive power of control winding under variable speed is given. The calculating capacity of the machine with a diode bridge rectifier load is proposed. The expression between the current of control winding and parameters of generator is derived. To achieve global searching and improve optimization efficiency, the improved real-coded genetic algorithm is presented. The prototype of 18 kW, 270 V with DC output is designed. The results show this scheme has prominent effect to reduce reactive power of control winding, and the capacity of converter can be reduced to 1/3 of output rated power, which makes the dimension of inverter much smaller. This is rather benefiting for the applications to the above isolated supply system.

Dual stator-winding induction generator based automotive power generation system using direct power control

This paper presents a novel direct power controlled dual stator-winding induction generator (DWIG) system. The voltage control mechanism of the DWIG is analyzed, based on which the influence of the control winding instantaneous power on the output dc voltage is disclosed. The strategy of the direct power control (DPC) for the DWIG is proposed. No inner current loops and no PWM modulator block are required. Fast control on the control winding instantaneous power is achieved, because the required voltage on the control winding, which restricts the active and reactive power errors into a certain band, is directly selected from an optimal switching table (OST) within each working period. Detailed theoretical analysis for the derivation of the OST in the DPC controlled DWIG system is presented. Experimental results on an 18kW DWIG system are provided to demonstrate the effectiveness and robustness of the proposed control strategy during the variation of rotor speed and output power.

Sensorless control of permanent magnet synchronous machine based on a novel sliding mode observer

A position sensorless control scheme of surface-mounted permanent magnet synchronous machine (SPMSM) using a novel sliding mode observer (SMO) is proposed, suitable for applications where low speed and standstill operations are not required. Compared with traditional SMO, the sign function is replaced by a saturation function, to increase the precision of the rotor position estimation at low speed and the stability of the system at high speed, the estimated back electromotive force (back-EMF) is feed back to current observer. To achieve better filtering effect and simplify the hardware structure, a variable cut-off frequency low-pass filter is designed. Details of the implementation of the algorithm are fully explored. Experimental results on an PMSM drive system used in electric bicycle are provided to demonstrate the effectiveness and robustness of the proposed control strategy.

The Dual Stator-Winding Induction Generator for Wide-Speed-Range Operation

The voltage regulation strategy of the dual stator winding induction generator (DWIG) system operating over a wide speed range is presented. The instantaneous power theory is employed to analyze the instantaneous power of the control winding, and then the control scheme for the DWIG system with diode bridge load is obtained. The components of the control winding currents which are produced on the control winding flux and its normal determine the instantaneous reactive power and active power, and further influence the DC voltage of load connecting across the power windings and DC voltage of the static excitation controller (SEC) on the control windings. The simulation and experiment are implemented on an 18kW DWIG system, and the validities of the analysis and voltage regulation strategy are verified.

Research on DTC Control Strategy of Induction Starter/generator System

The advancement in power electronic makes the cage-type induction machine (IM) be suitable to be used as a starter/generator (S/G). Because the IM must start the engine to a high ignition speed with a low voltage battery, a method which employs delta-connection stator winding is proposed. Similarities and differences of basic direct torque control (DTC) in IM with delta-connection and star-connection stator winding are investigated. In order to convert the IM from starting mode to generating mode smoothly, a method by changing the direction of electromagnetic torque is presented. The disadvantage of basic DTC is that it has a big torque ripple. In generating mode, the torque ripple can cause voltage ripple. In order to decrease voltage ripple, DTC based on space vector modulation (SVM-DTC) is researched. Creation method of reference voltage vector which includes change trend and magnitude information of flux and torque is presented. Experimental results verify that the induction starter/generator system can successfully start the engine with the low voltage battery and can convert from starting mode to generating mode smoothly under basic-DTC. The system has a preferable stable and dynamic generation performance under SVM-DTC

Research on Dual Stator--Winding Induction Generator with Wind Energy

The new-style dual stator-winding induction generator (DWIG) is presented in the field of wind power supply. The performances of the system operating with 1:2.5 speed range with wind power supply under no-load and rating-load are simulated. The designs of excited winding circuit are presented. The results show the good voltage performances and the large output power can be controlled.

Design of servo motor controller applied in coaxial two-wheeled electric scooter

Servo system has been applied in the executive mechanism of coaxial two-wheeled electric scooter pose control. The pose control requires high accuracy and strong robustness of the servo system. However, the characteristics of servo system based on linear PID regulator are not very excellent. To improve the performances, a novel servo system of permanent magnet synchronous motor (PMSM), based on active-disturbance rejection controller (ADRC) theory, is presented in this paper. The proposed position servo system is suitable to coaxial two-wheeled electric scooter pose control, because of high accuracy, speedy response, no overshoot and strong robustness proved by simulation results.