| The traditional AC servo system includes servo drives with PG and reducers. The existence of reducer will bring many problems, such as low efficiency of drive, bulky, and high cost. Meanwhile the high-performance optical encoder configuration will increase system cost and reduce its reliability. Based on the research of mathematical models and control theory of direct-driven low-speed permanent magnet synchronous motor without mechanical reducer, this paper analyzed the method to improve the direct torque control performance in low-speed mode, engineering non-PG control, motor parameters self-learning methods, and also in-depth studied the achievement of the system with embedded Multi-tasks. Then completed software and hardware design for the electromagnetic deceleration type PMSM servo system.Firstly, this paper introduced the basic structure and mathematical models of the permanent magnet synchronous motor (PMSM), analyzed the basic principles of the permanent magnet synchronous motor direct torque control, discussed the role and methods of the voltage space vector in the direct torque control, and also analyzed the problems in basic DTC program.Secondly, in order to solve the problems like large torque ripple in basic DTC control, and seriously impacted the control performance by motor parameters, this paper proposed an advance control method which used space vector pulse width modulation direct torque control (SVM-DTC) to improve the system dynamic and static performance. The algorithms of this method include voltage vector generation and space voltage vector modulation. Then, by analyzing the theory and problems in normal speed estimating algorithms, this paper proposed a new speed estimating algorithm based on the detection of momentary power angle. In the self-learning mode, we could correct the motor parameter in speed estimating algorithm by comparing with the value which is detected by proximity switch, to realize engineering control without PG. This paper also analyzed the motor parameters self-learning methods, which based on the initial information of proximity switch, voltage and current signals, to improve the observation accuracy and performance in non-PG control. Then, the paper established the mathematical model of the basic DTC and SVM-DTC control about the electromagnetic deceleration type PMSM, and carried on the simulation in the environment of Matlab/Simulink. The results showed that, SVM-DTC got a good effect in reducing the electromagnetic torque ripple, and the stability of low speed.Finally, the paper realized the electromagnetic deceleration type PMSM servo control plan by the embedded technology of Multi-tasks , and completed the servo system's software and hardware design. The hardware took ColdFire series of 32 micro-controller MCF52235 as the control core, carried out a detailed design and analysis of the controller minimum system, signal sampling module, soft-switching inverter circuit, the signal drive and protection circuits and the system's auxiliary power. The software selected the modular structure which is based on embedded real-time operating system, and transplantedμC/OS-Ⅱto the micro-controller of MCF52235. Servo system software was divided into several task modules, analyzed the signal conversion, control algorithm, SVPWM output tasks and software implementation process of human-machine interface, together with the debugging and experimenting of the system's hardware and software, and then finally verified the feasibility and effectiveness of the system.
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