| DC-DC switching power converters have been widely used in different application scenarios due to their wide range of voltage conversion,high power conversion efficiency and their flexible topology.However,the application of a DC-DC converter with certain topology or control mode,is relatively narrow.Demands for functionality and adaptation are increasing,which call for converters that can adapt to a wider range of applications to reduce overall design costs.In conventional system design procession,each performance and ability often needs to be trade off after certain requirements are settled,for example,higher precision modulation or wider bandwidth;higher operating frequency or higher conversion efficiency;faster load transient response or lower output voltage overshoot/undershoot,they are difficult to achieve good performance at a same time.However,system performance can be greatly improved by adopting some specific circuits,such as transient-response-enhancement circuits,which can speed up system transient response and reduce output voltage overshoot/undershoot during transient load change.On one hand,it can improves system robustness and stability,protects rear-end modules of the whole system.On the other hand,it helps DC-DC designers to focus on optimizing other performance of the converter.Therefore,the performance and value of the whole system can be enhanced and the applicable range of the power system can be broadened.For conclusion,the researches about DC-DC transient enhancement circuit are of great scientific value and economic value.In this thesis,A BUCK converter,which base on the Pulse Width Modulation(PWM)control and Current Control Mode(CCM),and transient-response-enhancement circuits for DC-DC,which focus on larger load ability,smaller volume and fast transient response,will be research and designed.The BUCK converter in this thesis will be designed with 6.5 V maximum bus voltage,6 A maximum output current and output voltage range at 1 V to 4 V.At first,some crisis parameters will be determined based on loop requirement and application condition,in demand for small volume,compensation network with integrated active capacitance will be researched and designed.Then issues about when and how to introduce transient enhancement will be discussed and researched,transient-response-enhancement and its correlative circuits will be designed,which greatly reduces output voltage overshoot/undershoot caused by load change,at the same time variable compensation technology was adopted and loop regulation speed are boosted.At last,transientresponse-enhancement circuit will be optimized,a transient-response-enhancement tactic called Error Amplifier static voltage prediction will be proposed and its relevant predict circuit,operation circuit will be designed as well,which successfully achieve adaptive transient response enhancement for different application conditions and different load change strength,the equivalent bandwidth can be expanded under wider application range.Tactics and circuits proposed in this thesis will be analyzed,simulated and verified via Cadence and based on 0.35 ?m BCD process,comparisons and conclusions about transient response ability between three system proposed before will be made.Simulation results show that,compare converter system that with proposed transient-responseenhancement circuits to that with conventional structure,output voltage overshoot/undershoot is only 33.8% of converter with conventional structure and the whole transient response time is 12.2%,which achieve the desire goal. |
PDF Full Text Request