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Study On The Combinated Topologies And Control Methods Of The Basic DC/DC Converter

Posted on:2009-08-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q M LuoFull Text:PDF
GTID:1102360272475372Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
With the fast-developing of the technology, the technical specifications of DC/DC converter become higher and higher, how to improve them is one of the research hotspots in the power electronics area. Aiming at how to improve the power rate, the dynamic load performance, the capability to reduce the influence of the input voltage disturbance of the DC/DC converter, some basic and exploring researches on the combined topologies and control methods of the basic DC/DC converter have been done, the main researches are as follows.Firstly, the basic interleaved series DC/DC converters are proposed in this thesis. Using interleaved series BUCK converter as an example, the operation principle and property of the interleaved series converters are analyzed in detail, the results have shown that the voltage stresses of the switches in the interleaved series DC/DC converter are lower and the dynamic load performance of it is better when compared with the corresponding basic DC/DC converter. Therefore, the interleaved series DC/DC converters are adapted to the high input voltage situation.In order to perfect the basic theory of the double frequency converter, these researches as follows have been done. The topologies of the whole series of the basic double frequency converters are deduced according to the topology equivalent transformation. The operation mode of the basic and improved double frequency converters are studied, the method how to judge the operation mode of the improved double frequency converters is proposed. Based on the operation theory of the improved double frequency converter, the rule how to establish the value of the low frequency inductor is proposed, especially, the sub-harmonic oscillation of the low frequency inductor current is analyzed and the method to solve this problem is proposed.In order to optimize the topology of the double frequency converter, a new kind of hybrid double frequency converter is proposed, the high frequency cell is a three level cell and the low frequency cell is a two level cell respectively. When compared with the three level BUCK converter, the hybrid double frequency BUCK converter has higher efficiency. When compared with the improved double BUCK frequency converter, the voltage stress of the high frequency switches is lower, the output inductor and capacitor are smaller and the dynamic load performance is better. In order to improve the dynamic load performance and to reduce the influence of the input voltage disturbance, two voltage type and one cycle control methods are proposed, that is V2-OCC control and OVDC-OCC control. The control theories are described, the small signal models are set up and the frequency-domain analyes are performed, finally, the experimental results are given. The results have shown that adopting V2-OCC control method can get better dynamic load performance than adopting PID-OCC control method proposed before, however, the capacity to reduce the influence of disturbance of the input voltage is a little worse. When adopting OVDC-OCC control method, better dynamic load performance can be gotten and better capability to reduce the influence of the disturbance of the input voltage either.In order to realize over-current protection and current sharing control conveniently, a kind of current type and one cycle control method is proposed, that is C+-OCC, C--OCC and C-OCC. The control theories are described, the small signal models are set up and the frequency-domain analyes are performed contrastively, finally, the experimental results are given. The results have shown that the performanceof C+-OCC and C-OCC control is very close, however, adopting C+-OCC control can get better dynamic load performance. The C--OCC control has different performance when the input voltage and load current are changing, it is very interesting to find that output voltage will decrease when the input voltage increasing or load decreasing, which is different from the commom control methods. All in all, the C+-OCC control has the best performance among them. Basing on these above, the current type and one cycle control is used for controlling the improved double frequency converter successfully, the results are accord with what we expect.Moreover, a new ZVT auxiliary network is proposed, the operation principle and property of the BOOST converter based on the new network are analyzed. The results have shown that all switches realize soft switching within the whole input and output range, the circulating energy is small and the conducting losses are reduced, all in all, the efficiency is improved. Finally, the new ZVT network is used in the single phase bridgeless BOOST type power factor correction successfully, the experimental results have verified the correction of theory analysis.
Keywords/Search Tags:Interleaved Series Converters, Double Frequency Converter, Zero Voltage Transient, One Cycle Control
PDF Full Text Request
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