ارائه ي مبدل هاي جديد اصلاح ضريب توان

چكيده انگليسي :

187 New Power Factor correction PFC Converters Mehdi Ramezani m ramezani1@ec iut ac ir Date of Submission 2010 14 3 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Seyed Mohammad Madani madani104@yahoomail com Abstract In this thesis after a survey on isolated and Non isolated PFC converters and their problems features and a brief review on the applied controllers some of the applied soft switching methods on Non isolated bridgeless PFC converters are presented The Non isolated PFC converters can shap the input current of the rectifiers according to the related standards but because of the variable input power of a sinusoidal voltage there will be some rippels in the output voltage In isolated converters to reduce the output voltage ripple a storage capacitor can be placed in the converter to save some of the input power and release it during the zero crossing of the sinosidal input voltage Due to the limited band width of the voltage controller loop of the converter the storage capacitor voltage can increase when the output power decreases So a stprage capacitor with higher voltage rating should be installed which increases the total cost of the converter Several approaches are presented to reduce the maximum voltage stress of the bulk capacitor The approaches are negative magnetic feedback and frequency modulation In negative magnetic feedbackmethid the converter uses an extera winding to set a part of the bulk capacitor voltage in series with the input inductor to reduce the input current when the bulk capacitor voltage increases This method increases the converter complexity and its total cost In frequency modulation method the converter uses a variable frequency controller to control the converter The controller uses the frequency to control the bulk capacitor voltage and the duty cycle to control the output voltage With this method the converter does not need any extera components but the controller will be so complex and due to the variable switching frequency the magnetic component design will be more complex Another way to reduce the bulk capacitor voltage is to locat that in the low voltage side of the isolation transformer which makes the series inductance interval PFC converters In this family of PFC converters the bulk capacitor voltage is well limited but they can achieve class D standards which means that they produce more harmonic distortion Then the proposed PFC converters are presented The first proposed converter is a Zero Voltage Switching bridgeless PFC which uses an improved auxiliary circuit to achieve Zero Voltage Switching conditions for its main switches and diodes In this converter all of the resonant current flowes through the auxiliary circuit so there is no extera voltage or current stress on the main switches and diodes also the auxiliary switch operates in the ZCS conditions so it dos not introduce any switching loss in addition with that auxiliary circuit the converter uses lower component count compared with the similar ZVS converters After thet a new series inductance interval PFC converter is presented In this converter the duble processing energy is limited to the zero crossing moment of the input voltage by means of a magnetic feedback winding so the duble processing losses will reduce and can result in higher efficiency Both of the converters are analysed and a desighn strategy is presented for each of them and results are verified with PSIM simulation and experimental results Keywords Power factor correction PFC Bridgeless PFC Soft switching Series inductance interval PFC converters

رمضاني، مهدي

ارائه ي مبدل هاي جديد اصلاح ضريب توان

مبدل هاي اصلاح ضريب توان بدون پل , سوئيچ زي نرم , مبدل هاي اصلاح ضريب توان نوع اندوكتانس سري