Research On Hybrid Algorithm For Sensorless Srm Operation Control Strategy

Switched Reluctance Motor Drive System (SRD) has become one of the hot studies in thefield of speed control. As its core, Switched Reluctance Motor are widely used in industry,aerospace, automobile manufacturing industry and other aspects because of its simple structure,robust, low cost, wide speed range and high system efficiency, etc. However, due to thepresence of position sensor not only greatly reduces the system reliability but also increasingthe cost of SRD system, making the application of SRM has been limited. Therefore, thetechnology of indirect position detecting for sensorless SRM has become the major subjectcurrentlly.Firstly, a new power supply is proposed in this paper which mixed single-phase andtwo-phase conduction mode together based on 8/6 SRM. Traditional both single-phase andtwo-phase conduction mode have common in that a forced commutation appears for eachrotation of a stepping angle 15°in order to get a correct switch between the conducted phaseand shutdown phase. A new conducted way of stator winding is proposed in this paper calledmixed-conduction mode as A-AB-B-BC-C-CD-D-DA-A by analyzing the properties of SRMtorque angle and vector. The commutation interval of SRM is narrowed by subdividing thestepping angle of SRM under this new mixed-conduction mode and improves the positioningaccuracy of SRD position detection. Then, the commutation logic based on mixed-conductionmode is proposed through the analysis of motor winding inductance wave, which provides themain theoretical basis for the application of mixed-conduction mode used in 8/6 SRM.Secondly, based on the analysis of the linear inductance model of SRM in this paper, ascheme to detect the initial rotor position and to determine the initial conduction phase arestudied in this paper in the idea of current location. At low speeds, through the injection ofnon-phase with detected voltage pulse to get responsing current, which is compared with thecurrent threshold constantly to determine whether the time of winding commutation is coming.At high speeds, the position detection error is increased by mutual inductance and injectedpluse current that are occupied half of the current cycle. Using current gradient method in highspeeds will not only avoid this problem, but also to ensure good accuracy.Finally, combined with TI's TMS320LF2407 DSP, which is the core of the controller todesign the hardware and software of SRD system. Paper mainly used the control software toachieve indirect position detection scheme proposed in this paper with injected pluse at lowspeed and current gradient at high speed. Then draw the soft flow chart of SRM indirectposition detection based on the principle of conducting. The result of simulation and experimentverify the feasibility of SRM indirect position detecting under mixed-conduction mode.