Direct Instantaneous Torque Control System Designing Of SRM

As a new speeding motor, switched reluctance motor has been widely applied in many fields,such as textile, aerospace and many other fields. Especially on electric car industry, it has become a national key research projects in recent years. But subject to the limit of the structure, the serious phenomenon of torque ripple become the obstacles of market application. And the traditional control strategy can’t achieve ideal control effect. So in order to reduce the torque ripple, this paper chooses direct instantaneous torque control strategy as the research direction, illustrates how to implement the control theory from the angle of design.In this paper, a three-phase 12/8 pole with rated power of 7.5kW switched reluctance motor was used as the research object. First of all, this paper begins from the structure characteristics of the doubly salient reluctanc motor, analyzing the operation principle of switched reluctance motor.And deduces the relationship between the electromagnetic torque from current, inductance and rotor position angle under the ideal linear model. So it raises using the torque as the control parameters of direct instantaneous torque control method. Then this paper introduces the structure and principle of the direct instantaneous torque control system, analyzing how to reduce the torque ripple in a inductance cycle. Therefore, this paper designs torque estimation unit and torque hysteresis units as the key point, showing reasonable opened and closed angle can satisfy the constant torque output.Then on the hardware, this paper designs a control system circuit with the DSP chip TMS320F28335 which is designed by TI company based on the control strategy, and mainly introduces some working principle of circuit modules, including position detection module, current detection module, communication circuit and driving module in detail. On the software, this paper uses C language to write code according to the requirement of direct instantaneous torque control, introducing the programming thought and code of the double closed loop PI control and the digital position recognition, at the same time the algorithm and flow chart of communication function and speed calculation, etc are designed.Next, this paper writes software according to the control requirements of SRM, and software control process, the main function, initialization function, speed function, PI control function, etc are specified. Through the software debugging repeatedly, it finally realized the functions of right direction running, contrary direction running, stop, the acceleration and deceleration.At last, this paper makes a experiment to test direct instantaneous torque control system, getting related experimental data and waveform, and the experimental results are analyzed, and through the results can be seen that the motor is running stable, which proves the feasibility and correctness of this strategy. Then the future research direction was forecasted.