The System Simulation and Design of Inverter Air Conditioner

• Main Authors: Wu, Room-Haur, 吳榮豪
• Other Authors: Lon-Kou Chang
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/49040277010096428217

碩士 === 國立交通大學 === 電機與控制工程學系 === 86 === In this thesis we propose a top-down design method for air- conditioners drivenby inverters. We adopt the CLF/CLTD method and use the parameters of the structu and collected data of the weather to calculate the cooling load induced from heat sources. We modified the thermal equivalent model in Matlab and propose a practical model which includes the calculation of cooling load. Using this new method, we design three temperature controllers, those are(1) ON-OFF controller, (2) P controller. and (3) PI controller. The simulation results show that P controller already works very well. We also study the method to design the inverter for the air-conditioner. The inverter with three-phase PWM outputsis our choice. Five different modulation waveforms have been considered and analyzed here, those are sinusoidal wave, sinusoidal wave with the third harmoniccomponent, "2/5" trapezoidal wave, space vector wave, and modified trapezoidalwave. After the comparison of the five associated utilization of the dc voltages and the accumulated total harmonic distortions, we find that the 2/5 trapezoidal modulation wave is the best choice in our design. We use the circuit board with 8051 CPU to implement the function of the inverter. By carefully evaluating the performance of 8051, we propose a look-up table method to synthesize three-phase 2/5 trapezoidal PWM waves.The results have shown that our method can utilize the performance of 8051 to the upmost.The frequency modulation indices can be designed up to 21~23. This result shows our implementation method is pretty practical.