Fundamental Research On The Geared Reluctance Motor

The Geared Reluctance Motor (GRM) is a new kind of motor invented by the Automation Institute of BUPT (Beijing University of Post and Telecommunication). The motor is a type of reluctance one, whose torque is produced by the variety of reluctance between the stator and rotor. The GRM has the main merits of reluctance motors, such as simple structure, high efficiency, small starting current, large torque and strong overload ability. It can start in heavy load, and can run between CW and CCW frequently. The special characteristic of the GRM is that it combines the motor and the reduction gear in one, which simplified the structure, reduced the volume and weight, and improved the torque. It can be used in places where volume and torque is strictly restricted. The GRM has been bored for no long, and the thesis carried out fundamental researches on it, mainly including: 1. foundation of the parameterized linear modelThe main job of founding the linear model is to calculate the air-gap permeance. The rotor of the GRM is not salient pole, and variation of the air-gap is regular, so it is possible for establishing the parameterized linear model. By simplifying the rotor as a circle pole, the air-gap permeance math model was established, of which the structural parameters and the rotor angle are all the variable parameters. The model can compute the air-gap permeance at any rotor angle place automatically. When structural parameters of the GRM were changed, the model can adapt to the variation, and it is not necessary for the air-gap flux tube to be divided again. The model was verified by testing on the prototype and the finite element method. 2. foundation of the parameterized nonlinear modelThe equivalent magnetic circuit method was used to establish the parameterized nonlinear model. The iron core and the air-gap of the GRM were divided into several parts whose reluctance can be computed parametrically, and the magnetic network was made up by its geometric structure. The flux linkage function can be got by solve the magnetic potential balance equations, and its rightness was verified by the finite element method. It is the function not only of the current and rotor angle, but also of the numerous structure parameters, and multi variables can be altered in the function. How to get the flux linkage function is the fundamental problem of reluctance motors. It can be used to establish not only the static torque-angle characteristic model, but also the dynamic simulation model. 3. influence on the torque-angle characteristic exerted by change of the structure parametersBased on the nonlinear model, the torque-angle characteristic model was established, and its rightness was verified by testing on the GRM prototype. Then the torque-angle characteristics model was studied in detail for the first time by using the model. The influence on the torque-angle characteristic exerted by the change of structure parameters was explored in detail. Ways and design principles for improving the torque output of the GRM were summarized. 4. optimization design of the GRM structural characteristicsEach structure parameter has different influence on the GRM drive capability. To improve the torque/volume ratio as large as possible, it is necessary to optimize the GRM structure parameters. Based on the genetic-algorithms, and aimed at the largest torque output per unit volume of the motor, the thesis optimized the structure parameters of the GRM for the first time. The GRM is not only an electromagnetic energy mechanical energy converter, but also a mechanical reducer, so the design optimization must give consideration to both of the two functions. This was considered into the design constraints, such as the leakage flux constraint between poles, the strength constraint of the pole-shoes, the radius constraint of the stator and rotor, the height and the width constraint of the cycloid gear tooth, and the rounding of the tooth number. All the constraint conditions were formed into a penalty function, which is a part of the object function, to make the optimizing result meet the engineering practice. The procedure and examples of the design optimization were given. 5. design of the full digitalization controller for the GRMWhen the GRM structure parameters is decided, the actual drive capability it can give depends on the control quality of the control system, and a good controller hardware is the foundation of the control quality. The thesis has designed the full digitalization control system hardware for the GRM, and the main controller chip is DSP. The serial and the CAN communications interfaces were equipped, with steady power supply layout. The asymmetric half bridge driver circuit was designed, selected MOSFET as the main power device, and equipped with the RDC absorption network that can absorb the peak surge and protect the MOSFET. The high-performance gate driver circuit based on the IR2132 was presented. The feedback test methods of the position, speed and current were presented, which made foundation for the CCC control at low speed and the APC control at high speed. The full digitalization controller provides good hardware platform for further research on the control algorithm of the GRM.