【作者】 陈欣；

【导师】 许建平；

【作者基本信息】 西南交通大学 ， 电子信息（专业学位）， 2024， 硕士

【摘要】 三相PWM整流器被广泛应用于三相前端整流,主要有两种类型:三相电压型整流器(Voltage Source Rectifier,VSR)和三相电流型整流器(Current Source Rectifier,CSR)。三相电流型整流器本质上为降压型拓扑,具有较低启动电流与短路电流抑制能力,因此在工程上得到广泛应用。本文围绕三相Buck整流器的不对称SVPWM调制策略,以降低输入电流总谐波畸变(Total Harmonic Distortion,THD)和MOSFET开关管的电压应力为目标展开研究。本文首先分析了三相Buck整流器的拓扑架构、调制策略以及控制方法的研究现状,详细介绍了三相Buck整流器电路的工作原理,给出了SVPWM调制策略的矢量作用时间计算方法和分配策略,推导了间接电流控制策略的参考值计算公式。其次,对比分析了传统不对称三段式、对称五段式SVPWM调制三相Buck整流器的输入电流在扇区切换处畸变原因。提出了一种低输入电流THD的不对称五段式调制策略,通过改变有效矢量作用时间的分配方式,避免了在扇区切换处出现不规则PWM序列,提高了输入电流的质量。然后,针对高功率密度三相Buck整流器,对比分析了两种不对称PWM序列调制三相Buck整流器的直流链电流纹波特性。揭示了由于两种不对称PWM序列直流链电流纹波特性的不同,在输入电压相序改变时,同一种PWM序列调制三相Buck整流器的输入电流会产生畸变。提出了一种调制自适应算法,仿真结果表明,调制自适应算法调制三相Buck整流器在三相电压正负相序输入时均能实现输入电流无畸变。其次,低输入电流THD调制高功率密度三相Buck整流器的MOSFET开关管电压应力较高。本文在低输入电流THD调制策略基础上,通过优化零矢量的选择,在输出电感续流期间构建了新的电流回路,降低了MOSFET开关管的电压应力。最后,针对提出的三相Buck整流器的不对称调制策略,本文进行了仿真验证,并搭建了一台1k W的三相Buck整流器实验样机进行实验验证。仿真与实验结果验证了理论分析的正确性。更多还原

【Abstract】 Three-phase PWM rectifiers are broadly applied in three-phase front-end rectification,and there are two main types:three-phase voltage source rectifier and three-phase current source rectifier.Three-phase current source rectifiers are essentially step-down topologies with low start-up current and short-circuit current suppression capabilities,so they are widely used in engineering.In this paper,the asymmetric SVPWM strategy of the three-phase buck rectifier is researched,with the goal of reducing the total harmonic distortion(THD)of input current and the voltage stress of MOSFET switch.In this paper,the topology,modulation strategy and control method of the three-phase Buck rectifier are analyzed,the working principle of the three-phase Buck rectifier circuit is introduced in detail,the vector action time calculation method and allocation strategy of the SVPWM strategy are given,and the reference value calculation formula of the indirect current control strategy is derived.Secondly,the reasons for the distortion of the input current of the traditional asymmetric three-stage and symmetric five-stage SVPWM modulated three-phase Buck rectifier at the sector switching are compared and analyzed.In this paper,an asymmetric five-stage modulation strategy with low input current THD is proposed,which avoids the irregular PWM sequence at the sector switching and improves the quality of the input current by changing the allocation mode of the effective vector action time.Then,for the high-power density three-phase Buck rectifier,the DC chain current ripple features of two asymmetric PWM sequence modulated three-phase Buck rectifiers are compared and analyzed.It is revealed that due to the difference in the current ripple characteristics of the DC chain of the two asymmetric PWM sequences,the input current of the three-phase Buck rectifier modulated by the same PWM sequence will be distorted when the phase sequence of the input voltage is changed.A modulation adaptive algorithm is proposed,and the simulation results show that the modulation adaptive algorithm modulated three-phase Buck rectifier can achieve no distortion of input current when the three-phase voltage is input in both positive and negative phases.Secondly,the MOSFET switch voltage stress of the low-input current THD-modulated high-power-density three-phase buck rectifier is high.In this paper,based on the low input current THD modulation strategy,a new current loop is constructed during the freewheeling current of the output inductor by optimizing the selection of zero vector,which reduces the voltage stress of the MOSFET switch.Finally,for the proposed asymmetric modulation strategy of three-phase Buck rectifier,this paper carried out simulation verification,and built a 1k W three-phase Buck rectifier experimental prototype for experimental verification.Simulation and experimental results verify the correctness of the theoretical analysis.更多还原