Keyuan Huang

Maximum torque per ampere and flux-weakening control for PMSM based on curve fitting

This paper describes the MTPA (maximum torque per ampere) control strategy of Salient-pole PMSM (permanent magnet synchronous motor) and its flux-weaking control strategy. Salient-pole PMSM often used the MTPA control strategy, the method that MTPA curves obtained from look-up table is usually used, but it will reduce the real-time performance and reliability of the system. In this paper, electromagnetic torque Tem and the relationship of the AC-DC-axis currents id, iq can be derived with the curve fitting method directly. It approximates the original nonlinear equations into a set of two-dimensional linear equation, and the error analysis shows that the error in line with engineering requirements, so it is greatly simplifies and facilitates the actual operation. On this basis, the paper also introduces the phase-shifting controlled manner to achieve flux-weakening control. The control performance of motor with improved algorithm is analyzed through simulation, and the simulation results verify the validity and feasibility of the algorithm and theory.

Effect of the number of slots per pole on performance of permanent magnet generator direct-driven by wind turbine

The PMSG (permanent magnet synchronous generator) with the rated power of 2MW which is driven directly without gear system is designed by equivalent magnetic-circuit method. In order to study the characteristics of permanent magnet generator directly driven by wind turbine with the rated power of 2MW, comparative study of the performance both of no load and rated load was studied under different design features such as the choice of the number of slots per pole and the pole embrace. The results based on FEA (Finite Element Analysis) show that the appropriate choice of slot number per pole and pole embrace has a significant effect on the performance of direct-drive permanent magnet generators. It can weaken the effect of no load voltage harmonics and help the direct-drive permanent magnet generators to obtain the better performance

Sliding mode SVM-DPC for grid-side converter of D-PMSG under asymmetrical faults

This paper presents a new direct power control algorithm based on space vector modulation using sliding mode controller. For this algorithm, it introduces sliding mode controller to regulate the dc voltage, active and reactive power, and it is unnecessary to decompose the voltage and current into positive and negative sequence components, so its amount of calculation is greatly reduced. According to the simulation results, the proposed algorithm in this paper can achieve the smooth sine of input current at the grid-side converter of wind turbine under asymmetrical fault, which ensures the stable DC voltage and enhances the fairly good capability of fault ride-through for wind turbines under asymmetrical fault.

Some Practical Consideration of a 2MW Direct-Drive Permanent-Magnet Wind-Power Generation System

Nowadays, there has been much interest and studies in direct-drive permanent magnet synchronous generator (PMSG) due to its high efficiency and reliability with the rapid development of the power semiconductor devices. MW class permanent magnet synchronous generator (PMSG) is an important trend for larger capacity and higher power density. The present paper is aimed to outline the design, including optimal machine design, converter topology choosing and its control. Two 1MW back-to-back PWM converters with parallel connection are used to feed the power to the grid. The configuration, structure and control strategy of the converter are discussed. Some experimental results are given to illustrate the performance of the actual system.

A Novel Variable Step Hill-Climb Search Algorithm Used for Direct Driven PMSG

Introduced a new type of maximum power point tracking strategy (MPPT) based on variable step hill-climb which use power perturbation to search for maximum power and record the maximum power related to the turbine speed. Besides, adopted power feedback control for maximum power control based on direct-driven wind turbine with permanent magnet synchronous generator (D-PMSG). The algorithm was proved by MATLAB simulation.

Sensorless control for direct-drive PMSG wind turbines based on sliding mode observer

In order to obtain the accurate information of generator speed and angle, and alleviate the shortcomings of the speed sensor, this paper presents a sensorless vector control model of permanent magnet synchronous generator (PMSG) based on sliding mode observer (SMO) in the direct-drive permanent magnet wind power generation system. The proposed observer is easy to implement and less sensitive to parameter variations. But since it is the discontinuous control, the high frequency chattering problem would be produced in the conventional PMSG Bang-Bang control. In this paper, the saturation function is adopted to replace the discontinuous sign function and solve the problem successfully. The validity of the proposed estimation and control algorithms are shown by simulation studies on a 1MW PMSG wind turbine and are further demonstrated by experimental results on a 7.5KW practical PMSG wind turbine.

Improved method on flux-weakening control of permanent magnet synchronous motor in electric vehicles

Described the operating principles of permanent magnet synchronous motor used in electric vehicles. Introduced weakening principle due to its mathematical models. Traditional control after decoupling often used PI controller, often influence of motor parameters, affecting the robustness of control system, especially operated at above the rated speed on flux weakening condition. Analyzed the proportional resonant (PR) controller features, against its defects, presented a control method based on an improved PR (IPR) controller and phase-shift flux weakening control strategy. Finally, simulation results showed the control strategy has good robustness and dynamic performance. The validity of this method is verified.

Open-circuit fault diagnosis of single converter device for directly-driven wind power system

To overcome the complex calculation and the interference vulnerability of traditional fault-diagnosis methods, this paper presents a fault diagnosis method for open-circuit faults of single converter device of the direct-driven permanent magnet wind power system on the basis of variable features of faulty current. The open-circuit fault of converters will seriously affect the operation of the direct-drive permanent magnet wind power system For improving the reliability of the converter system, this method which takes the current as diagnostic parameters, detects the fault occurrence based on the slope variation of the current Park vector phase, positions the motorside fault according to the range located by the Parks vector phase of the motor-side average current and determines the grid-side fault position in line with the current polarity of each grid-side phase. Hereafter, simulation models verify the accuracy and the reliability of the proposed scheme, and the robustness against the disturbance such as load mutation, grid voltage drop, etc.

Sensorless control of direct-driven permanent magnet wind power generation system based on improved MRAS

Permanent magnet motors are coming more and more popular in wind generation applications. In the high efficient wind power generation system, the accurate information about rotor position is very important. MRAS schemes offer simpler implementation and require less computational effort. Because the voltage model involves pure integrator in the classical model reference adaptive system (MRAS). This will cause initial value and drift problems. These problems affect the precision of rotor position. This paper describes a improved sensorless vector control strategy of PMSG based on MRAS. It uses high-pass filter in the voltage model to avoid these problems. To avoid phase and amplitude errors brought by the high-pass filter, it has to insert high-pass filter in the current model simultaneously. To improve dynamic performance the system uses fuzzy controller to adapt the cut-off frequency on-line and replace the traditional PI controller. We implement a 7.5kW direct-drive generation system centered about the DSP, and through some laboratory experiments, we will show that the improved method is capable of precise estimating the rotor position under the condition of high or low speed.

Experimental evaluation of sensorless control for doubly-fed induction wind power generator

This paper analyzes the implementation of the sensorless control strategy for a doubly-fed induction generator (DFIG) for wind energy. The proposed algorithm can directly obtain the information of rotor position and speed via simple arithmetic operation by measuring the stator voltage, the rotor and stator currents. A DFIG sensorless digital control system has been carried out based on TMS320F2808 DSP. The experimental results indicate that the proposed method can precisely estimate the rotor position and speed, the system can achieve excellent control performance.