Development of Photovoltaic Interactive Inverter Using Immittance Converter in High-Frequency Link

新研制的光伏公用事业交互式逆变器额定功率为3kW。在逆变器中，在绝缘高频链路上新设计了一个集成T-LCL型阻抗变换器，工作频率为19kHz。在60Hz时，在没有反馈控制的情况下，获得失真系数为3%的正弦电流，并且受实用电压的幅度和波形畸变的影响很小。当市电电压逐步变化时，正弦波电流的波形和幅值不变，瞬态振荡在0.1毫秒内消失。光伏交互逆变器整体效率在90%以上。阐明了5种谐振阻抗变换器的频率特性、电压电流传递特性、效率特性等基本特性。当负载阻抗等于特性阻抗时，所有类型的阻抗变换器都具有最大的效率。在LCL型阻抗变换器中，如果电抗器的Q值为100，则最高效率为98%。实验结果表明，LCL型导通变换器的最高效率为98.6%，混合型导通变换器的最高效率为99.4%。很明显，谐振频率和源频率的偏差可以允许±5%。在非接触式能量传输系统供电的载波中的功率接收端是阻抗变换器的有用应用之一。在该系统中，接收端的高频恒流通过阻抗变换器转换成恒压，然后进行整流，得到直流恒压。阻抗变换器输出的整流技术是光伏公用事业交互式逆变器中常见的。

Newly developed photovoltaic utility interactive inverter is 3kW rated power. In the inverter, there is a transformer integrated T-LCL type immittance converter newly designed in insulated high frequency link which worked at 19kHz. At 60Hz, a sinusoidal current of 3% distortion factor is obtained without the feed back control, and is little affected by the amplitude and the wave form distortion of the utility voltage. Waveform and amplitude of the sinusoidal current don't change, when the utility voltage changes stepwise, and the transient oscillation disappears in 0.1 millisecond. The overall efficiency of the photovoltaic interactive inverter is over 90%.Basic characteristics such as frequency characteristics, voltage-current transfer characteristics, efficiency characteristics were clarified on resonant immittance converter of 5 types. The immittance converter of all types has maximum efficiency when the load impedance is equal to the characteristic impedance. The maximum efficiency is 98%, if the Q of the reactor is 100 in the LCL type immittance converter. In experiments, the 98.6% maximum efficiency has been obtained using the LCL type immittance converter, and 99.4% maximum efficiency has been obtained using the hybrid type immittance converter. It became clear that the deviation of the resonant frequency and source frequency could be permitted ± 5%.The power receiving end in the carrier supplied power by a Non-Contact Energy Transfer System is one of the useful application of the immittance converter. In the system, the high frequency constant current at the receiving end is converted into a constant voltage by the immittance converter, then it is rectified, and a DC constant voltage is obtained. The rectifying technology of the output of the immittance converter is common to the photovoltaic utility interactive inverter.