Research On Direct Instantaneous Torque Control Of Switched Reluctance Motor

Switched reluctance motor drive system, referred to SRD, is a new type of drive system. Today it has been used in many fields. The system has many advantages, such as simple and sturdy structure, relatively low cost and so on. What more important is that it has a relatively high starting torque and starting current is low. The system has many controllable parameters, so the speed controller is easy to design. However, because of magnetic saturation and the doubly salient structure of the motor, torque ripple exists during operation. This paper uses a kind of new control strategy called direct instantaneous torque control strategy and optimizes the hardwire circuit in order to reduce the torque ripple and make the system more stable and reliable.In this paper, it first analyze the composition and the work principle of the switched reluctance motor, and then gives the mathematical model of switched reluctance motor. Based on the torque production, the paper analyzes its characteristics. The control strategy of SRD system is called direct instantaneous torque control. The system uses the torque parameter to form a closed-loop control and establish the main framework of the system. The result of the instantaneous torque can get from the calculation of the simple linear model. Phase voltage and phase current can be measured directly and become the variable quantity in the model. The formula proving phase voltage can affect the instantaneous. Design the hysteresis controller to make the instantaneous torque to follow the reference given. In addition, the paper basing on the different relative position of the rotor, divides the running regions into single-phase conduction region and bipolar conduction region, and focused on analyzing the process in the commutation torque vector and the current allocation strategy to achieve the goal current and reducing the torque ripple. In the closed-loop speed control, the strategy uses a new PI speed controller which containing the elimination term. This method can avoid the shock and the overshoot during the period in starting and sudden increase load. So the system can run steady.On this basis, this paper aiming at a 5.5kW three-phase 12/8 pole switched reluctance motor for the object, designs the consummate hardware circuits. It contains control circuit, protection circuit, drive circuit, power supplies circuit and so on. In the control system, dsPIC33FJ128MC706 is the main programming chip. From the experiment, it obtains the waveform and the result. It confirms that the system can run stable in different conditions and the strategy of direct instantaneous torque control is effective especial in reducing the current and torque ripple aspect.