基于电力电子变压器隔离变压的复合矿用变频器

Mine inverter based on isolation and transformation of power electronic transformer

目前矿用变频器与工频变压器分离放置,占用过多井下工作空间,且变频器输出电压谐波含量高、波形质量差。针对上述问题,分析了变压器工作频率与体积的理论关系,得出在传输功率相同的情况下,与工频变压器相比,高频变压器的尺寸更精简,体积更小,功率密度更高。用电力电子变压器(包含高频变压器的DC-DC变换器)取代常见拓扑中的中间滤波电容,提出了一种基于电力电子变压器隔离变压的复合矿用变频器拓扑结构,该拓扑中全控型开关器件IGBT的数量仅为全部功率器件数量的一半,变频器结构更紧凑、体积更小,且减少了开关损耗,降低了硬件复杂度和生产成本,提升了效率和可靠性。给出了该拓扑中三相整流输入级、中间隔离变压传输级和三相变频输出级的控制策略,采用120°坐标系下快速空间矢量脉宽调制(SVPWM)算法控制输出级,以输出理想的可变频三相对称正弦交流电压。通过仿真和实验分析该变频器各级的稳态和动态特性,结果表明:该变频器可实现变频输出及电压等级的二次变换,输出调压范围更灵活;120°坐标系下快速SVPWM算法降低了输出电压谐波含量,输出的三相电压波形良好。

At present,the mine inverter and the power frequency transformer are placed separately,which occupies too much underground working space.And the inverter output voltage has high harmonic content and poor waveform quality.In order to solve the above problems,the theoretical relationship between transformer operating frequency and volume is analyzed.It is concluded that under the same transmission power,the high-frequency transformer has a more streamlined size,smaller volume and higher power density compared with the operating frequency transformer.The intermediate filter capacitor in the common topology is replaced by power electronic transformer(DC-DC converter containing high frequency transformer).The paper proposes a composite mine inverter topology based on power electronic transformer isolation and transformation.The number of fully controlled switching devices IGBT in this topology is only half of the total number of power devices,which makes the inverter structure more compact and smaller,reduces the inverter switching losses,reduces hardware complexity and production costs,and improves efficiency and reliability.The control strategies of the three-phase rectifier input stage,the intermediate isolation transformer transmission stage and the three-phase variable frequency output stage in this topology are given.The fast space vector pulse width modulation(SVPWM)algorithm in 120°coordinate system is used to control the output stage to output the ideal variable frequency three-phase symmetric sinusoidal AC voltage.The steady-state and dynamic characteristics of the inverter at all levels are analyzed through simulation and experiment.The results show that the inverter can realize the secondary conversion of the inverter output and voltage level,and the output voltage regulation range is more flexible.The fast SVPWM algorithm in 120°coordinate system reduces the output voltage harmonic content,and the output three-phase voltage waveform is good.