三相高功率因数整流器控制策略研究及实现

【作者】 董娟；

【导师】 潘永湘；

【作者基本信息】 西安理工大学 ， 控制理论与控制工程， 2001， 硕士

【摘要】 电解电源广泛应用于冶金和化工领域，其特点是提供强大的直流电流，而且必须连续供电；同时由于耗电量大，要求电源效率较高。国内原有的电解电源大多数采用晶闸管或二极管整流，功率因数较低，而且向电网注入了大量谐波。这样不仅造成了电网的谐波污染，更使电能的生产，传输和利用效率降低。 针对这些问题，本文对整流装置的功率因数提高及谐波抑制问题展开了讨论，在对三相功率因数校正原理研究分析的基础上，提出了两种不同电路拓扑结构（三相六开关Boost型、三相单开关Boost型）下的控制方案。 三相六开关Boost型PFC电路常用的控制方式有间接电流控制和直接电流控制，直接电流控制又包括滞环比较方式、三角波比较方式、dpo变换方式等。其中间接电流控制是基于稳态电流的控制法，所以动态响应速度慢，存在较大的瞬态直流偏移，而且到电路参数的变化对控制效果有较大影响。滞环比较方式简单易行，响应速度快，控制精度高，但开关频率随负载变化及扰动的影响而不固定，所以给滤波电路的设计带来很大困难。三角波比较方式器件的开关频率固定，滤波容易，但电流响应速度较滞环比较方式慢。dpo变换方式可以作到无稳态误差跟踪，控制精度高，但控制涉及到复杂的变换。可见这些控制方法都存在不同程度的缺点，而且难于实现数字化。为此，第三章中提出了内环采用空间矢量调制（SVPWM）、外环采用多模式的控制方案。在这一方案中外环的多模式控制（PI／自适应模糊控制）控制能较好的适应负载的非线性变化，内环的简化后的空间矢量调制易于实现控制方案的数字化。对该控制方案用MATLAB5.2编写了相应的仿真程序，并和已有的两种典型控制方案的控制效果进行了对比。仿真结果表明新的控制算法明显优于己有的控制算法。 三相单开关Boost型PFC电路因其输入电流波形能自动跟踪输入电压波形而被广泛用于高功率因数的场合中，但是传统的常频定占空比输出电压反馈控制，并不能消除输入电流的谐波，这使在设计5kw以上功率的整流器时只能考虑性能与价格的折中方案。采用输出电压反馈控制不但对谐波的抑制效果不好，而且动态特性也不好，输入电压变化时存在较高的瞬态偏离，使功率器件要承受较大的冲击，设计时要留出足够的安全额度。针对这些问题在第四章中提出了谐波注入与输入电压前馈相结合的控制方案。其中的谐波注入技术能很好的抑制输入电流的低次谐波，输入电压前馈控制使系统的动态性能得到较大的改善。对该方案用Pspice7.1进行了仿真分析，仿真结果表明该方案功率因数校正作用明显，而且对低次谐波的抑制效果明显优于传统电压反馈控制。 二一 针对所选用的两种控制方案，第五章中设计了通用的控制器硬件结构，及其外围电路。根据系统实时性需要，选用INTEL公司生产的微处理芯80C196KC作为系统控制核心，由双CPU结构的单片机最小系统及键盘显示组成。外围电路主要包括检测传感电路，控制驱动电路，报警保护电路，为了今后系统功能的扩展，控制核心部分还预留了串行通讯接口。根据硬件结构和系统控制方案，编制了相应的系统应用程序，在第六章中对此进行了详细的介绍。最后，对第二种控制方案进行了物理性实验，实验结果与仿真结果基本一致。更多还原

【Abstract】 Since the rectifiers for electrolysis are used widely in the fieldof metallurgy and chemical industry, it must supply powerful andcontinuous current. So the rectifier must have high coefficient ofperformance. The conventional thyristor or diode rectifiers haveinherent drawback have low power factor and the harmonics of the linecurrent relatively high. It not only induces harmonics pollution butalso decrease the coefficient of performance.Pointing to these problems, the paper presents respectivestrategies of the tow kinds of topologies (three-phase six-switch Boostrectifier and three-phase single-switch Boost rectifier) on the baseof debating about the power factor correction and harmonics inhibitiontechnologies and investigating the operating principle of three-phasePFC rectifier.The conventional control methods of three-phase six-switch Boostrectifier can be divided to indirect current (PAC) mode and directcurrent mode. The direct current mode includes hysteresis currentcontrol (HCC), triangular wave comparing control (TWCC), dpo conversioncontrol (dpoCC). Basing on steady condition, the phase and amplitudecontrol (PAC) has a low dynamic response and dc current offset that isaffected by the parameters. The hysteresis current control has a fastdynamic response, good accuracy. However, it switching frequency varieswith the dc load current, which makes the filter devising difficult.The triangular wave comparing control has a fixed frequency but has alow dynamic performance. The dpo conversion control can track currentwithout any error in steady state, but it need complex computation. Itis obvious that these control method have shortcomings in differentextent and difficult to digitalized. So the paper presents a strategyin chapter 3, which use the space vector PWM control inner loop switchand multimode control (PI/adaptive fuzzy control) adjust the outer loop.The multimode control (PI/adaptive fuzzy control) has robustperformance with load occurring nonlinear changes. The simplified spacevector PWM control is easy to carried out by microcontroller. By thelIlimp1ement of MATLAB5. 2, a simu1ation model for three--phase AC to DCrectifier is set up. Comparing the nove1 method with several traditioncontrol ari thmet ic, the result of s imulat ion show that it has favorableperformance -Three--phase sing1e--switch Boost rectifiers are common1y used forthree--phase high--power--factor (HPF) app1 ication since their inputcurrent wave--shape automat ical 1 y fo11 ows the input vo1 tage wave shape.However, if the three--phase sing1e--swi tch Boost rect ifier is imp1ementwi th the convent ional constant--frequency out--vo1 tage feedback contro1,the rect ifier input current exhibit re1ative1y 1arge harmonics. As aresu1t, at power levers above 5kW, the harmonics imposes severe design,performance and cost trade--offs. The out--vo1tage feedback cannot reducethe harmonics effective1y, moreover it 1ead to high transientdeviations of the output voltage with respect to steady state va1ue.Due to an out--voltage ’overshoot during a step--up transition,’power--stage semi conductor components wi th a higher vo1tage rat ing areusua1ly required to maintain the necessary design margin between themaximum vo1tage stress of the components and their vo1tage rating.Pointing to these prob1ems, the paper introduces a newharmonic--inject ion technique wi th the feedforward contro1 in chapter4. By this technique a 1ow harmonics can be achieved with an exce11enttransient performance. A simu1ation of this strategy by the using ofPspice7. 1, the resu1t show that it has obvious power factor correctioneffect and has an advantage of harmonics inhibition.The genera1--purpose contro1ler and a few of periphera1 devices canimp1ement the strategies in chapter 5. The contro11er part isaccomp1 ished by the Inte1 80C196KC, inc1uding the double--chip CPUsstructure with keyboard and disp1ay functio更多还原