• Journal of Power Electronics
• /
• 제8권1호
• /
• pp.23-34
• /
• 2008

This paper deals with a Direct Torque Control (DTC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) for the Electric Vehicle (EV) propulsion system using a Neural Network (NN). The Conventional DTC with optimized switching lookup table and three level torque controller generates relatively large torque ripples in an electric vehicle motor drive. For reducing the torque ripples, a three level torque controller is hereby replaced by the five level torque controller. Furthermore, the switching lookup table of the five level torque controller based DTC is replaced with a Neural Network. These DTC schemes of an IPMSM drive are simulated using MATLAB/SIMULINK. The simulated results are compared with the conventional DTC and it is found that the ripples in the torque, as well as in the stator current, are reduced drastically.

• Journal of Electrical Engineering and Technology
• /
• 제10권2호
• /
• pp.574-585
• /
• 2015

This paper aims to improve the performance of conventional direct torque control (DTC) drives proposed by Takahashi by extending the idea for 5-level inverter. Hybrid cascaded H-bridge topology is used to achieve inverter voltage vector composed of 5-level of voltage. Although DTC is very popular for its simplicity but it suffers from some disadvantages like- high torque ripple and uncontrollable switching frequency. To compensate these shortcomings conventional DTC strategy is modified for five levels voltage source inverter (VSI). Multilevel hysteresis controller for both flux and torque is used. Optimal voltage vector selection from precise lookup table utilizing 12 sector, 9 torque level and 4 flux level is proposed to improve DTC performance. These voltage references are produced utilizing a hybrid cascaded H-bridge multilevel inverter, where inverter each phase can be realized using multiple dc source. Fuel cells, car batteries or ultra-capacitor are normally the choice of required dc source. Simulation results shows that the DTC drive performance is considerably improved in terms of lower torque and flux ripple and less THD. These have been experimentally evaluated and compared with the basic DTC developed by Takahashi.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권7호
• /
• pp.1061-1067
• /
• 2008

Direct Torque Control[DTC] and Vector Control are the two schemes developed for high performance induction motor drives. DTC based induction motors are being increasingly used in various industrial applications. DTC offers fast torque response and better speed control with lesser hardware and processing costs as compared to vector controlled drives. However, conventional DTC suffers from high torque ripple, current harmonics and low performance during torque transients. In this paper a new Direct Torque Control[DTC] method of induction motor is presented. In comparison with the conventional DTC method, the PWM technique is applied to proposed control method. In this method, decoupling mechanism is not required and the torque, the flux magnitude are under control using PI controllers and generating the voltage command for inverter control. Therefore torque and speed ripple could be reduced in comparison with the conventional switching table DTC.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.434-437
• /
• 2009

To realize the advantages of e-Paper, driving systems should be separated from panels to keep its superiority in thin, light, and flexible. For this purpose, this paper develops a panel hot-plugging driving system for R2R cholesteric LCD. Its performance is verified by implementing an e-Badge application. Satisfactory results are obtained.

• Journal of Electrical Engineering and Technology
• /
• 제13권3호
• /
• pp.1223-1231
• /
• 2018

The direct torque control (DTC) scheme features a simple structure thanks to stator flux-oriented control. It has the advantage of robustness against motor parameters variation since only the stator resistance is involved in the control scheme. On the other hand, the disadvantage of DTC is large torque ripple. To reduce the torque ripple, many studies on DTC-space vector modulation (DTC-SVM) schemes, which modulate the duty ratio with a fixed switching cycle, have been proposed. However, there is the difficulty in obtaining the duty ratio for DTC-SVM. Hence, this paper proposes a new duty ratio selection and stator flux calculation methods for reducing torque ripple. Simulations and experiments were carried out to determine the validity of the proposed method. The proposed scheme has simplified the duty ratio command and achieved the same control performance as the conventional duty ratio modulation method without using the information of motor parameters.

• 전력전자학회논문지
• /
• 제20권5호
• /
• pp.421-428
• /
• 2015

An advanced direct torque control (DTC) with pulse width modulation (PWM) method is presented in this paper. The duty ratio calculation of the selected voltage vector is based on the voltage functions of the selected voltage vector according to the sector angle. The proposed DTC uses a conventional DTC scheme with six sector divisions and switching rules. However, the winding voltages are supplied by the PWM approach. Furthermore, the duty ratio of the switching voltage vector is determined by the flux, torque error, and motor speed. The base voltage that shall determine the duty ratio can be calculated by approximate voltage functions according to the voltage angle. For the calculation of base voltages, second-order quadratic functions are used to express the output voltage of the selected voltage vector according to voltage angle. The coefficients for the second-order quadratic functions are selected by the voltage vector, which is determined by the switching rules of the DTC. In addition, the voltage functions are calculated by the coefficients and voltage angle between the voltage vector and rotor position. The switching voltages from the calculated duty ratio can supply the proper torque and flux to reduce the ripple and error. The proposed control scheme is verified through practical experimental comparisons.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.62.5-62
• /
• 2001

In this paper, we present a novel control method for the plant with an integral mode and long time delay. In a constant time delay problem, one can independently adjust the set response and the disturbance response by the proposed DTC without any additional control variables. To verify the effectiveness of the proposed DTC, it is compared with Matausek´s DTC and Normey-rico´s DTC which were recently proposed. Simulation results are given and the superior performance of the proposed scheme over the conventional schemes are successfully verified.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
• /
• pp.319-319
• /
• 2000

In this paper, A dead-time compensator (DTC) for the processes with long dead-time is proposed. The processes which consist of dead-time, time-constant, gain are estimated by the linear least squares method in the frequency domain. A Smith predictor(SP) modified by including a filter becomes a two degree of freedom DTC. So the proposed DTC can yield the desirable setpoint and load disturbance responses separately. PI controller is used for the primary controller and the filter is tuned to be robust. Simulation examples demonstrate the properties of the proposed DTC.

• 전자공학회논문지SC
• /
• 제44권5호
• /
• pp.62-70
• /
• 2007

본 논문에서는 일정 토크영역에서 승압형 PFC 컨버터와 직접토크제어(DTC) 방법을 사용하여 BLDC 모터의 구동 시스템을 DSP(TMS320F2812)로 구현하였다. 기존의 6단계 PWM 전류제어와 달리 미리 정한 샘플시간 마다 간단한 look-up 표로부터 2상 도통 모드에 대한 인버터의 전압 상태 벡터를 설정함으로써 원하는 전류파형을 만들었으며 이로부터 기존의 전류제어기보다 훨씬 빠른 토크 응답특성을 얻을 수 있었다. 또한 BLDC 모터의 비 이상적인 사다리형 역기전력에 의해 발생되는 저주파 토크변동을 저감하기 위하여 위치 loop-up 표를 사용하였다. 아울러 역률을 보정하기 위해 승압형 PFC 컨버터를 구성하였고 이 때 전파 정류된 입력전압과 출력전압, 인덕터의 전류에 의해 평균전류모드 제어 방식으로 80 kHz마다 PWM 듀티(duty)가 조절 되도록 하였다. 이와 같이 복잡한 제어 알고리즘은 초고속 DSP의 출현으로 PFC와 DTC 알고리즘이 동시에 제어가 가능하며, 본 논문에서는 DTC 알고리즘을 구현할 때 DSP의 일반 범용의 출력포트를 사용하여 구현하였고 단지 PFC에서만 1개의 PWM을 사용하여 디지털 제어기를 구현하였다. 실험을 통해 DTC 알고리즘과 PFC 컨버터를 이용한 BLDC 모터 구동 시스템의 타당성과 효용성을 보였고, 실험결과로부터 PFC 컨버터를 사용하지 않았을 때는 역률이 약 0.77이었으나 PFC 컨버터를 사용하였을 때는 부하변동에 관계없이 약 0.9997로 크게 향상됨을 확인하였다.

• Journal of Electrical Engineering and Technology
• /
• 제2권4호
• /
• pp.468-477
• /
• 2007

The DTC of voltage source inverter-fed PMSMs is based on hysteresis controllers of torque and flux. It has several advantages, namely, elimination of the mandatory rotor position sensor, less computation time, and rapid torque response. In addition, the stator resistance is the only parameter, which should be known, and no reference frame transformation is required. The DTC theory has achieved great success in the control of induction motors. However, for the control of PMSM drives proposed a few years ago, there are many basic theoretical problems that must be clarified. This paper describes an investigation into the effect of the zero voltage space vectors in the DTC system and points out that if using it rationally, not only can the DTC of the PMSM drive be driven successfully, but torque and flux ripples are reduced and overall performance of the system is improved. The implementation of DTC in PMSM drives is described and the switching tables specific for an interior PMSM are derived. The conventional eight voltage-vector switching table, which is namely used in the DTC of induction motors does not seem to regulate the torque and stator flux in a PMSM well when the motor operates at low speed. Modelling and simulation studies have both revealed that a six voltage-vector switching table is more appropriate for PMSM drives at low speed. In addition, the sources of difficulties, namely, the error in the detection of the initial rotor position, the variation of stator resistance, and the offsets in measurements are analysed and discussed.