Kazuhiro Ohyama

Comparative analysis of experimental performance and stability of sensorless induction motor drives

This paper compares the experimental performance of three flux and speed observers for speed-sensorless induction motor drives and discusses the cause of their differences. The small signal analysis using the linearized model is carried out to analyze stability. Three methods are generally accepted to be representative candidates for high sensorless performance, namely: 1) rotor-flux model reference adaptive system (MRAS); 2) torque-current MRAS; and 3) adaptive nonlinear flux observer. Many other sensorless methods improved these methods. The paper discusses baseline conditions for the experiments and the stability analysis, which include matched load inertia, specified speed estimator dynamics, and sensorless operation within a speed control loop. For the comparison tests in the paper, the speed estimation dynamics of the methods are the same; this is important for parameter sensitivity. The paper concentrates on the low-speed performance, and all results shown are under sensorless speed control.

Design using Finite Element Analysis of Switched Reluctance Motor for Electric Vehicle

Inthis paper, Switched Reluctance Motor(SRM)to beemployed electric vehicle (EV)isdesigned using finite element method(FEM).Thestatic torque ofSRM is estimated withthemagnetic field analysis. The temperature rise withtimeofSRM isestimated withthe heattransfer analysis. First, thestatic torque and temperature rise withtimeof600WSRM included inan experiment set, andarecompared withthecalculated results usingFEM underthesameconditions. The validity ofmagnetic field analysis andheattransfer analysis isverified bythecomparisons. Also, the60 [kW]SRMemployed inEV,whoseoutput characteristics areequal to1500[cc] gasoline engine, isdesigned with themagnetic field analysis andheat transfer analysis.

Small-signal stability analysis of vector control system of induction motor without speed sensor using synchronous current regulator

This paper presents a stability analysis of a speed sensorless vector control (SSVC) system of an induction motor. The stability analysis takes into account the effects of three current control loops. The poles and zeros of the transfer functions for the rotor speed are calculated to investigate the influences of controller parameters and motor parameters. The theoretically derived step responses are compared with the experimental results. Also, the Bode diagrams of the transfer functions for the torque producing current are calculated. The settling time of the step responses of the rotor speed for the various designs of the current regulator (CR) is studied. This paper discusses the suitability of different CR methods for the SSVC system of an induction motor.

Excitation interval control of switched reluctance motor considering derivative of inductance

The electric vehicles need high efficient torque control system. Therefore, this paper proposes the novel excitation interval control method. The excitation intervals are concentrated around the rotor position where the derivative of inductance becomes maximum values. The efficiency of proposed method is superior to the efficiency of conventional methods.

Sensorless operation of SRM drives from starting to steady state

It is known that control strategies for most electrical machines are derived based on machine parameters, which are constant for most of the excitation range. However, due to the salient pole nature of Switched Reluctance Motor (SRM), the machine inductance is not only a function of the rotor angle but also is a function of the excitation current. This complicates the development of control strategies for such drive systems. The position information requirement is a limitation of SRM. The shaft position sensors are normally used for this purpose. These sensors reduce the reliability of the drive. Efforts are on to replace the position sensor with suitable estimation technique. In this paper, an overview of the different existing sensorless starting methods and their shortcomings are explained and finally, a starting method is proposed. Also this paper presents a method of position estimation for SRM. The method is suitable from starting to full speed. It ensures smooth starting without initial hesitation.

Experimental verification of variable speed wind power generation system using permanent magnet synchronous generator by wind turbine emulator

This paper presents the experimental results of variable speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG). The back to back PWM converters are utilized as converters for the VSWPGS. The experimental results are obtained by the test bench using the wind turbine emulator. The wind turbine emulator are reproduced the behaviors of windmill by the servo motor drives. The mechanical torque reference to derive the servo motor is calculated from windmill wing profile, the wind velocity and windmill rotational speed. The VSWPGS using PMSG employs the vector control system to control the torque and speed of PMSG in the converter side. The windmill rotational speed is controlled to maximize the efficiency of wind turbine against wind speed in low-and middle-range. When the wind speeds exceeds the rated value, the windmill rotational speed and output power are controlled to be the rated values by the pitch angle control system. And the active power and reactive power are controlled in the inverter side, and generated power is sent to the grid-connected power generation while controlling the DC link voltage to be constant at the same time.

Automatic Turn-off Angle Control for High Speed SRM Drive

This paper present a new approach to the automatic control of the turn-off angle used to excite the switched reluctance motor (SRM) for electric vehicle (EV). The controller selects the turn-off angle that supports the most speed operation of the motor drive system. This control consists of classical current control and speed control depends on lookup table to take best result of the motor. The turn-on angle of the main switches of inverter is fixed at 0deg and the turn-off angle is variable depend on the reference speed. The motor, inverter and control system are modeling in Simulink to demonstrate the operation of the system

Design of high efficient switched reluctance motor for electric vehicle

This paper proposes the design of switched reluctance motor (SRM) to obtain high motor efficiency. The first step of design makes the principle improving motor efficiency clear. The cross sections and axial shapes of rotor and stator cores are designed by using the magnetic field analysis with 2D and 3D finite element methods. The designed SRM is produced experimentally, and is tested to certify the performance.

Experimental Assessment with Wind Turbine Emulator of Variable-Speed Wind Power Generation System using Boost Chopper Circuit of Permanent Magnet Synchronous Generator

This paper presents experimental results and its assessment of a variable-speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG) and boost chopper circuit (BCC). Experimental results are obtained by a test bench with a wind turbine emulator (WTE). WTE reproduces the behaviors of a windmill by using servo motor drives. The mechanical torque references to drive the servo motor are calculated from the windmill wing profile, wind velocity, and windmill rotational speed. VSWPGS using PMSG and BCC has three speed control modes for the level of wind velocity to control the rotational speed of the wind turbine. The control mode for low wind velocity regulates an armature current of generator with BCC. The control mode for middle wind velocity regulates a DC link voltage with a vector-controlled inverter. The control mode for high wind velocity regulates a pitch angle of the wind turbine with a pitch angle control system. The hybrid of three control modes extends the variable-speed range. BCC simplifies the maintenance of VSWPGS while improving reliability. In addition, VSWPGS using PMSG and BCC saves cost compared with VSWPGS using a PWM converter.

Modeling and simulation of permanent magnet synchronous generator wind power generation system using boost converter circuit

This paper proposes variable-speed wind generator system using the Boost chopper system. The boost chopper system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates armature current of the generator with the boost chopper circuit to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of wind turbine. The hybrid of three control modes extends the variable-speed range. The boost chopper system simplifies the maintenance and improves the reliability and reduces the cost in compare with PWM converter system. extensive.