The Research And Implement Of Switched Reluctance Motor Drive

Switched reluctance motor drive system (SRD) is a very promising drive system, its outstanding advantages makes it of sharp competitiveness in the future variable-speed drive market. Due to the double saliency structure and profound magnetic saturation of switch reluctance motor (SRM), as well as the impulse-like excitation, system analysis and control face great challenge. This paper do some optimization in the SRD hardware circuit design and software implementation (mainly on control strategy).In order to design a new kind of SRM controller of high dynamic performance that considering the nonlinear and time-varying characteristics of magnetic parameters and disturbance-rejection, the current controller of the system employed hybrid control strategy that would make full use of the advantages of each control mode. Current-hysteresis chopping control (CCC) and back emf decoupling PI type single polarity PWM voltage chopping control (VC) was used at low-power, while single pulse control, also called angle position control (APC) was used at high-power or high-speed. The functional condition of these control mode and how to realize the smooth transition between each other was expounded from the respect of hardware and software design. The experiment results fully proved that these control mode played their advantages in the different stages of the mechanical characteristic respectively, and realized seamless connection between each other.For the sake of wider system operating range, faster dynamic response and minimized torque ripple, the single-phase and two-phase mixed conduct mode and four quadrant operation control was adopted in this paper. Experiment results showed that mixed conduct mode can make the current smoother and torque ripple reduced; And four quadrant operation control not only expanded the system work scope,but also maked torque control more flexible.The configuration of the inverter was 1.5 switches and diodes per phase with passive boost circuit as the front-end voltage source. Experiment results indicated that this kind of topology can speed up the demagnetization of the phase windings and in some cases quicken the excitation speed, thus the output power and efficiency can be increased and motor speed range would be expanded.In order to ensure the shutoff RC-snubber circuit of switch transistor works well in both switch on and switch off state, the author used theories of circuit analysis when analysed the working condition of the snubber circuit in detail, and then the calculation method of the RC parameter of snubber circuit was given with the system discussed in this paper as the example. Finally, the effectiveness of the calculation method was verified through the actual working effect of snubber circuit and the measured waveform of switch transistor terminal voltage.