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Study On The Control Technique Of Voltage Regulator With Fast Transient Response

Posted on:2006-12-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:F Y WangFull Text:PDF
GTID:1102360182461602Subject:Power electronics and electric drive
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With the increasing of microprocessor operation speed and dynamic load change, better load step-change transient response of voltage regulator (VR) is required. To improve the transient response performance of VR, both power stage and control technique of power converter need to be considered. In our dissertation, we will focus on the study of V~2 control technique and V~2C control technique which have fast load transient response.The transient behavior of buck converter with ESR is analyzed in detail when a step load change is applied. The simulation results show a good agreement with the analytic expression obtained. Based on which an in-depth study is carried out on V~2 control technique. Small signal model of buck converter with V control in continue conduct mode (CCM) is derived by using state space average method. The y parameters of buck converter with V control is also derived. Both theoretic analysis and simulation results show that the load transient response performance of V~2 control technique is better than current mode control technique. VR may operate in discontinue conduct mode (DCM) when the load is light. The input power stage and output power stage small signal model of buck converter with V~2 control operating in DCM are derived by using state space average method. Based upon which, the output impedance, line-to-output and control-to-output transfer functions are derived, from which we know that the transient response performance of V~2 control technique in DCM is better than current mode control technique. The frequency-domain and time-domain simulation results show a good agreement with the theoretic analysis results.As V~2 control technique can't control load current, V~2C control technique is proposed by added the current feedback into the inner loop of V~2 control technique. Small signal model of buck converter with V~2C control in CCM is derived by using state space average method. Based up on which, the output impedance, line-to-output and control-to-output transfer functions are obtained. Theoretic analysis and simulation results show that for power switching converter operating in CCM, V~2C control technique has a better transient control performance than V control technique. The small signal model of input power stage and output power stage of V~2C control buck converter operating in DCM are also derived. Based up on which, the output impedance, line-to-output and control-to-output transfer functions are obtained. The theoretic analysis and simulation results, both frequency-domain and time-domain, show that for the power switching converter operating in DCM, V~2 control technique has a betterload step-change transient response performance than V2C control technique.The transient response performance of boost converter with various control technique is also studied. From the study of output voltage ripple waveform of boost converter with ESR, we conclude that V control technique can't be applied to the control of boost converter. The small signal model of V2C controlled boost converter operating in CCM is derived by using state space average method. Based upon which, the output impedance, line-to-output and control-to-output transfer functions are obtained.. Theoretic analysis and simulation results show that for boost converter operating in CCM, V2C control technique has a better transient response performance than current mode control technique. The small signal model of input stage and output stage are derived for boost converter in DCM with V2C control. The ouput impedance, line-to-output and control-to-output transfer functions of which are derived based on the small signal model. The theoretic analysis results show that the transient response performance of V2C controlled boost converter in DCM is better than that of current mode control technique. The simulation results of frequency-domain and time-domain have a good agreement with the theoretic analysis results.A universal small signal model of voltage mode, current mode, V2 mode and V2C mode control techniques, which can be used for any one of these four control techniques, are derived from comprehensive study of these four kinds control techniques. The parameters of the model for each of these four control techniques are given, analyzed and compared.In order to verify our theoretic analysis and simulation results, a 100W buck regulator is set up. The input voltage of the prototype is 12 V DC and the output voltage is 5V DC. The current mode control, V2 model control and V2C mode control technique have been applied to the prototype. The experimental results have a good agreement with theoretic analysis and simulation results.
Keywords/Search Tags:Switching mode power supply, Voltage regulator, V~2 control technique, V~2C control technique, Load fast changing, Transient response
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