Research On SVM-DTC AC Variable Frequency Speed Regulation Based On Model Reference Adaptive System

At present, wide attention is paid on the asynchronous motor variable frequencyspeed regulating system, however, two of the most widely used strategies as vectorcontrol and direct torque control are not perfect, and traditional system withphotoelectric encoder to detect the motor speed is vulnerable to environment,therefore this topic proposed a SVM-DTC strategy based on the model referenceadaptive system to control the motor.Firstly, this paper analyzed the complex structure of the asynchronous motor andthe transformating principle among the three phase stationary coordinate system, twophase stationary coordinate system and two phase rotating coordinate system.according to the conversion relationship, we established the mathematical model ofasynchronous motor in different coordinate system; we proposed the SVM-DTCvariable frequency speed regulating control strategy of induction motor andestablished the observation model of the stator flux and electromagnetic torque underthe two-phase static coordinate system, then analyzed the implementation method ofthe SVPWM and the reconstruction principle of asynchronous motor stator voltage.In addition, this paper studied speed sensor technology, and put forward the motorspeed identificating method based on model reference adaptive system, thenconsidering the pure integral element, we proposed a low pass filter model referenceadaptive speed identification strategy.Secondly, we established the SVM-DTC variable frequency speed regulatingcontrol system based on model reference adaptive system under Matlab/Simulinkplatform, then proved its feasibility and high speed detecting precision and speedcontrol performance.Thirdly, we designed the hardware of this system, especially the AC to DC andDC to AC circuits, as the rectifier circuit adopt traditional diode to realize itsfunction, and designed the filter circuit to reduce the output voltage pulsation of therectifier; the inverter circuit adopt the intelligent power module to simplify thehardware circuit and improve system reliability; In addition, we used the DSP motioncontrol circuit based on PCI bus to realize variable frequency speed regulatingfunction and the communication with PC.At last, this system made the experiment platform in universities as thebackground, and based on Visual C++to program control algorithm and design thevisual interface. This system is safe, convenient to control, and the control algorithmis open, the user can to write algorithms and modifying parameters.Experimental results show that the hardware circuit adopting intelligent power module instead of the discrete component improves its higher reliability of theinverter circuit. The technology of model reference adaptive system shows its highspeed identification precision, the space vector modulation of direct torque controlstrategy solutes problems consist in the vector control system and the direct torquecontrol system and shows its high dynamic and static performance of speedadjustment. Overal, this system has high perfprmance of variable frequency speedregulation.