DITC-direct instantaneous torque control of switched reluctance drives

This paper presents an online instantaneous torque control technique for switched reluctance machines called direct instantaneous torque control. The method comprises two novel aspects. First, torque is estimated as a function of terminal quantities, i.e., flux linkage and phase current. Hence, torque estimation is independent of the rotor position. Secondly, high-bandwidth drive performance is obtained by implementing a digital torque hysteresis controller. Thus, the method works without torque profile functions and auxiliary phase commutating strategies. Therefore, the control algorithm offers a wide drive operating range without the use of a high-resolution shaft position sensor or sensitive position estimation techniques. Experimental and simulation results are presented in this paper.     

Optimizing performance in switched-reluctance drives

This article discusses the requirements of electric vehicle traction drives and the consequences to the control strategies of a switched reluctance motor drive. The selection of these control strategies for different operating regions in the torque-speed diagram is also discussed. To test different control strategies, a specialized simulation program was constructed. The simulation results and the implementation of the optimization strategies are discussed. Finally, the measurement methods and the test results are presented     

Control of switched reluctance drives for electric vehicleapplications

Dynamic controllers of switched reluctance drives adjust at least three variables, i.e., current amplitude, turn-on, and turn-off angles. In electric vehicle (EV) applications high efficiency of the drive over a wide speed range, wide torque bandwidth, and low torque ripple under varying DC-bus voltage conditions are important design goals. Hence, controllers of switched reluctance drives for EVs usually have a complex structure. In this paper, the demands on control accuracy of switched reluctance machine traction drives and the traction controller sampling frequency, which are necessary to take advantage of the switched reluctance machine dynamic capabilities, are discussed. To integrate the traction drive, the control commands need to be actualized with a sampling frequency of at least 100 Hz to meet the high-dynamic requirements of modern vehicle control systems, e.g., active cruise control, antislip control, and active damping of mechanical drivetrain oscillations. It is found that the switching angles have to be adjusted within one-tenth of a mechanical degree. This study shows that switched reluctance drives can fulfill all requirements needed for electric propulsion using standard microcontrollers or digital signal processors     

High-dynamic four-quadrant switched reluctance drive based on DITC

This paper presents the development of a four-quadrant switched reluctance machine (SRM) drive for high dynamic applications. Comprehensive fundamentals and analysis for operating switched reluctance machines in four quadrants are presented. The drive is designed based on a high dynamic control strategy called Direct Instantaneous Torque Control (DITC). The functionality of DITC is discussed in detail for both motoring and generating operation. A methodology to generate switching functions directly by the hysteresis torque controllers for SRMs is proposed. The proposed controller was prototyped and tested on a digital signal processor/field-programmable gate array development platform. High dynamic operation in both motoring and generating mode and the transition between these modes are validated by experimental results presented at the end of this paper.     

High-dynamic direct average torque control for switched reluctance drives

A technique was developed to estimate online average torque of switched reluctance machines. This novel online average torque and energy ratio estimation technique can be used for closed-loop torque control, i.e., direct average torque control. This closed-loop torque control algorithm continuously adjusts the reference torque by changing switching angles and reference current to maintain constant and accurate average shaft torque at a commanded torque level. Using the estimated average torque for regulation, the control structure can be simplified and decoupled from DC-bus voltage variations and other secondary control input parameters, such as temperature. The switched reluctance drive controller used in this study was developed and implemented for a 55 W electric-vehicle traction drive.