• Journal of Power Electronics
• /
• v.15 no.5
• /
• pp.1244-1255
• /
• 2015

This paper presents a new multi-machine robust control based on an electric differential system for electric vehicle (EV) applications which is composed of four in-wheel permanent magnet synchronous motors. It is based on a new master-slave direct torque control (DTC) algorithm, which is used for the control of bi-machine traction systems based on a speed model reference adaptive system observer. The use of an electric differential in the design of a new EV constitutes a technological breakthrough. A classical system with a multi-inverter and a multi-machine comprises a three-phase inverter for each machine to be controlled. Another approach consists of only one three-phase inverter for several permanent magnet synchronous machines. The control of multi-machine single-inverter systems is the subject of this study. Several methods have been proposed for the control of multi-machine single-inverter systems. In this study, a new master-slave based DTC strategy is developed to generate an electric differential system. The entire system is simulated by Matlab/Simulink. The simulation results show the effectiveness of the new multi-machine robust control based on an electric differential system for use in EV applications.

• Journal of Power Electronics
• /
• v.10 no.5
• /
• pp.477-484
• /
• 2010

A pulse width modulation-voltage source inverter (PWM-VSI) is used for variable speed permanent magnet synchronous motor (PMSM) drives. The PWM-VSI fed PMSM has two major disadvantages. Firstly, the PWM-VSI DC-link voltage limits the magnitude of the PMSM terminal voltage. As a result, the motor speed is restricted. Secondly, in a low speed range, the PWM-VSI modulation index declines. This is caused by a high DC-link voltage and a low terminal voltage ratio. As a result, the distortion of the voltage command and the stator current are increased. This paper proposes an optimal pulse amplitude modulation (PAM) control which can adjust the inverter DC-link voltage by using a buck-boost DC-DC converter. At a low speed range, the proposed system can reduce the distortion of the voltage command, which improves the stator current waveform. Also, the allowable speed range is extended. In order to verify the proposed method, experimental results are provided to confirm the simulation results.

• Journal of the Korean Society for Railway
• /
• v.10 no.1 s.38
• /
• pp.51-56
• /
• 2007

In this paper, control schemes are developed for a propulsion system(Converter/Inverter) in electrical train. A robust controller for PWM converter is proposed. The converter controller consists of a PI controller for DC output voltage and a current controller using error-space approach for maintaining the sinusoidal current waveform and unity power factor. This proposed method is based on characteristic ratio assignment(CRA) method which has the advantage to design the optimal gain to meet the referenced response and overshoot within the limit range. Inverter system is controlled by vector control and slip frequency control. At low speed region, vector control scheme is applied to control instantaneous torque and slip frequency control is performed under overmodulation region and one pulse mode. Because output voltage of converter contains harmonics ripple at twice input ac line frequency, control scheme is developed to reduce the pulsating torque current. The performance of propulsion system will be verified by simulation and prototype experimental results.

• Journal of Power Electronics
• /
• v.6 no.1
• /
• pp.52-66
• /
• 2006

This paper proposes a wind energy conversion system connected to a grid using a self-excited induction generator (SEIG) based on the maximum power point tracking (MPPT) control scheme. The induction generator (IG) is controlled by the MPPT below the base speed and the maximum energy can be captured from the wind turbine. Therefore, the stator currents of the IG are optimally controlled using the indirect field orientation control (IFOC) according to the generator speed in order to maximize the generated power from the wind turbine. The SEIG feeds a (CRPWM) converter which regulates the DC-link voltage at a constant value where the speed of the IG is varied. Based on the IG d-q axes dynamic model in the synchronous reference frame at field orientation, high-performance synchronous current controllers with satisfactory performance are designed and analyzed. Utilizing these current controllers and IFOC, a fast dynamic response and low current harmonic distortion are attained. The regulated DC-link voltage feeds a grid connected CRPWM inverter. By using the virtual flux orientation control and the synchronous frame current regulators for the grid connected CRPWM inverter, a fast current response, low harmonic distortion and unity power factor are achieved. The complete system has been simulated with different wind velocities. The simulation results are presented to illustrate the effectiveness of the proposed MPPT control scheme for a wind energy system. In the simulation results, the d-q axes current controllers and DC-link voltage controller give prominent dynamic response in command tracking and load regulation characteristics.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.1
• /
• pp.3-8
• /
• 1987

The conventional autosequentially commutated current-fed inverter (ASCI) is widely employed with the induction motor drives for speed control. Howener, this inverter has a limit of high power and high frequency indution motor drives. One of the limitations is to be found in the commutation capacitors in the main circuit of this inverter. A new current-fed gate turn-off thyristor (GTO) inverter is developed. This inverter is composed of the main GTO bridge configuration and the improved energy rebound circuit (ERC)without the commutation capacitor. This inverter works stable at high frequency from light load to heavy one. The improved ERC is used not only to rebound the load reactive power to the dc link, but also to return the power in the load to the ac source. The new GTO inverter circuit and the characteristics of the inverter induction motor drives are explained and analyzed.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.230-233
• /
• 1998

The conventional PI controller are fragile in parameter variation and load-variation. Therefore, in this paper, a speed control algorithm based on the Fuzzy PI controller is proposed for the high performance speed control of a voltage-source inverter to drive 3-phase induction motors. The computer simulation results show that the proposed controller are more excellent control characteristics than conventional PI controller in transient-state and steady-state response.

• Proceedings of the KIEE Conference
• /
• 2001.04a
• /
• pp.277-280
• /
• 2001

This paper presents a speed sensorless implementation of digital speed control system of Surface Permanent-Magnet Synchronous Motor(SPMSM) drives with a direct torque control(DTC). The system presented are stator flux and torque observer of stator flux feedback control model that inputs are current and voltage sensing of motor terminal with estimated rotor angle for a low speed operating area, two hysteresis band controllers, an optimal switching look-up table, rotor speed estimator, and IGBT voltage source inverter by using fully integrated control software. The developed speed sensorless control system are shown a good motion control response characteristic results and high performance features using 1.0Kw purposed servo drive SPMSM.

• Journal of Power Electronics
• /
• v.5 no.1
• /
• pp.45-54
• /
• 2005

This paper presents an application of SR drives for LSEV's(Low Speed Electric Vehicles) which are used for golf and leisure. Two types of 5[HP] SRM's and its drive system are designed and tested. In order to be energy saving and have effective braking during deceleration, a multi-level inverter is proposed. For the precise switching angle control, a new type of analog encoder is proposed. A current control is adopted for soft starting and an angle control is adopted at high speed to increase efficiency. Drive characteristics and performance are shown with test results.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.255-257
• /
• 1994

The V/F slip frequency constant control methods are used for driving induction motor with load commutated current source inverter, that is. constant V/F and slip frequency driving is used to load commutate the inverter below the critical frequency, while constant voltage and variable frequency and slip frequency driving are used in above the critical region. In order to applicate the load commutated current source inverter to the general use, speed control range of induction noter is selected to two times at rated frequency. Therefore, economical application is possible because of the maximum reduction of the condenser of the inverter output port. The use of the proposed force commutated circuit improves the false operation of force commutated circuit and inverter commutation failure which are produced by the influence of the lower-order harmonics of the conventional load commutated current source inverter at starting.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.241-243
• /
• 2003

By development of power electronics technology, the increasing of inverter's switching frequency lead to the development of speed control technology of induction motor. But the surge voltage including harmonic component in output waveform can cause the motor to generate power losses, torque ripple, acoustic noise and oscillation. This paper is analyzed the characteristics for switching surge of adjustable speed drive and is presented the problem by inverter.