基于仿输出电压纹波的开关电源控制技术研究

发布时间：2018-04-04 18:46

本文选题：纹波控制技术　切入点：稳定性　出处：《合肥工业大学》2017年硕士论文

【摘要】：对于电压调节模块而言,轻载转换效率和负载瞬态响应速度是其性能的重要衡量指标。在实际中,很多应用场合对这些指标的要求日益苛刻,这也促使基于输出电压纹波的控制技术越来越广泛的被应用于电压调节模块中。虽然基于输出电压纹波的控制技术普遍具有瞬态响应速度快、轻载效率高的突出优点,但是这类控制技术也存在着稳定性易受输出电容等效串联电阻(Equivalent Series Resistance,ESR)的影响以及稳态精度较差的问题。目前,针对基于输出电压纹波控制技术的稳定性易受输出电容ESR影响这一问题,主要的解决方案有斜坡补偿技术、电感电流纹波反馈结构和电容电流反馈技术。斜坡补偿技术将采样电感电流得到的斜坡补偿电压引入至反馈控制回路中,但是这种方案会降低开关变换器的动态性能,而且会增大输出电压的稳态偏差量;电感电流纹波反馈结构将电感电流纹波信息引入至反馈控制回路中,该方案实现简单,但很难兼顾系统稳定性和输出电压稳态偏差;电容电流反馈技术将电容电流引入至反馈控制回路中,由于需要检测电容电流,导致成本相对较高,而且误差放大器的加入,增加了控制电路的复杂程度和设计难度。针对基于输出电压纹波的控制技术存在的稳定性问题,以及现有解决方案的不足,本文提出了仿输出电压纹波(Simulated Output Voltage Ripple,SOVR)的解决方案,并将其应用于固定导通时间(Constant On-Time,COT)控制和电压型滞环控制这两种典型的基于输出电压纹波控制的Buck变换器中。详细阐述了SOVR结构的工作原理,并分析了其在电感电流连续导电模式(Continuous Conduction Mode,CCM)以及断续导电模式(Discontinuous Conduction Mode,DCM)下的工作特性。通过仿真结果,对比了已有的稳定性改善方案和SOVR解决方案在CCM和DCM情形下的稳态性能。仿真结果表明SOVR和电感电流纹波反馈结构都可以较好的解决纹波控制技术存在的稳定性问题,但相比之下,SOVR结构具有更好的稳态性能。为验证理论分析和仿真结果的正确性,在实验室搭建了相应的实验样机。实验结果表明:SOVR和电感电流纹波反馈结构均可以消除输出电容ESR对系统稳定性的影响,但电感电流纹波反馈结构会对稳态误差产生影响,SOVR结构具有更好的稳态性能。
[Abstract]:For voltage regulation module, the efficiency of light load conversion and the transient response speed of load are important indicators of its performance.In practice, the requirements of these parameters are increasingly demanding in many applications, which makes the output voltage ripple based control technology more and more widely used in voltage regulation modules.Although the control technology based on output voltage ripple generally has the outstanding advantages of high transient response speed and high light load efficiency,However, the stability of this kind of control technology is easy to be affected by the equivalent series resistance of output capacitance and the problem of poor steady-state accuracy.At present, the stability based on output voltage ripple control technology is easily affected by output capacitance ESR. The main solutions are slope compensation, inductance current ripple feedback structure and capacitive current feedback technology.The slope compensation technique introduces the slope compensation voltage from the sampling inductance current into the feedback control circuit, but this scheme will reduce the dynamic performance of the switching converter and increase the steady-state deviation of the output voltage.The inductance current ripple feedback structure introduces the inductance current ripple information into the feedback control loop. The scheme is simple, but it is difficult to give consideration to the stability of the system and the steady-state deviation of the output voltage.Capacitive current feedback technology introduces capacitor current into feedback control circuit. Because of the need to detect capacitance current, the cost is relatively high, and the addition of error amplifier increases the complexity and design difficulty of the control circuit.In view of the stability problem of output voltage ripple based control technology and the shortcomings of existing solutions, this paper proposes a solution of imitating output voltage ripple Output Voltage ripplette so VRR.It is applied to two typical Buck converters based on output voltage ripple control, which are constant on-time control and voltage hysteresis control.The working principle of SOVR structure is described in detail, and its working characteristics under continuous Conduction mode (CCM) and discontinuous Conduction mode (DCM) are analyzed.Based on the simulation results, the steady-state performance of existing stability improvement schemes and SOVR solutions in CCM and DCM cases are compared.The simulation results show that both SOVR and inductor current ripple feedback structure can solve the stability problem of ripple control technology, but the structure has better steady-state performance.In order to verify the correctness of theoretical analysis and simulation results, a corresponding experimental prototype was built in the laboratory.The experimental results show that both the output capacitance ESR and the inductor current ripple feedback structure can eliminate the influence of the output capacitance ESR on the stability of the system, but the inductance current ripple feedback structure will affect the steady-state error of the system.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN86

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