Design and implementation of double closed-loop system of brushless DC motor based on sliding mode control
In this paper, sliding mode control (SMC) is used in double closed-loop system of brushless dc motor(BLDCM), which improves speed tracking performance of BLDCM. Kinetic equation of motor is established according to mathematical modeling of motor, then design sliding mode controller by using kinetic equation. Sliding mode controller regulates speed in speed loop, and SMC strategy makes speed control of BLDCM have many advantages of quick response, strong robustness, small overshoot and so on. Current loop regulated by proportional-integral-differential(PID) control lets BLDCM limit maximum current to automatically protect system when BLDCM is in a state of overload. Through simulation with Matlab, it is obvious to see that system designed by this proposed scheme has better control effect than double closed-loop system all using PID control. Experimental platform is set up by K60 microcontroller, and it verifies feasibility of controller in actual control.
Modeling and simulation of the double-closed loop control system of counter rotating permanent magnet brushless DC motor
Unmanned underwater vehicle (UUV) has extensive and important use in military and civilian. The traditional power system of UUV adopts rotating propeller propulsion system, and has the following main disadvantages: low efficiency of power system, big noisy and large size. For the shortcomings of UUV power system, the research studies the new power system — counter rotating permanent magnet brushless DC motor (BLDCM). The research infers the mathematical model of counter rotating permanent magnet BLDCM according to the ordinary permanent magnet BLDCM, and designs the speed-adjusting controller. The speed-adjusting controller adopts double-closed loop control system that inner loop is current loop and outer loop is speed loop, and the research conducts the modeling and simulation of counter rotating permanent magnet BLDCM based on Matlab/Simulink. The simulation results show that the design of double-closed loop controlling system is consistent with theoretical analysis. Compared to the previous UUV power system, the new power system improves greatly power system efficiency, reducing significantly noise, and greatly reducing the volume and saving space. Therefore, this research proposes the double-closed loop control system of counter rotating permanent magnet brushless DC motor, and has some value for promotion of UUV power system.
The Influence of the Supervision of Psychotherapy upon being Therapeutic: II: Modes of Influence of the Supervisory Relationship *
Through supervision, the student develops those innate personal characteristics which are highly important in being therapeutic. In making conscious use of “reality identification” by the student with his teacher, we must take care to avoid certain pitfalls. What is not wanted is transference identification. To help avoid this, we must select appropriate teachers as supervisors. The student should also have more than one supervisor, as this tends to protect against the development of over-idealization on the part of the student, and of omnipotence on the part of the teacher. Personal characteristics of both students and supervisors are extremely important. A good supervisory experience is the most likely vehicle for developing those qualities in the student which will, in time, lead him to function most therapeutically.