Development of a solar power conditioner using diode-clamped linear amplifiers without any ac inductor nor EMI filter

本项目的目的是开发一种不使用任何交流电感和EMI滤波器的太阳能功率调节器，它使用二极管钳位线性放大器作为主功率电路。二极管钳位线性放大器由串联的MOSFET组成，其源端受到直流电压水平的抑制。这种配置类似于二极管钳位多电平逆变器。通常使用的二极管钳位多电平逆变器一般只使用n沟道器件。另一方面，二极管钳位线性放大器则使用补充功率MOSFET、p沟道和n沟道器件作为功率器件。二极管阻尼线性放大器可以向交流负载提供正弦输出电压，而不需要任何交流电感或滤波器，就像传统的线性放大器一样。串联MOSFET中的一个在工作区域的激活状态下工作。其他MOSFET工作在导通或关断状态，大大降低了工作在有源状态时的功耗，本课题首先针对二极管钳位线性放大器提出了一种新的电流控制方法和电流控制电路。采用十二级二极管钳位线性放大器，通过实验验证了其工作原理和性能。结果表明，该电路在正常负载和短路情况下均具有较高的电流控制精度和较低的电流纹波。接下来，利用两个十二级二极管钳位线性放大器和一个直流电压均衡器，将所开发的电路应用于交流电源接口太阳能功率调节器的单相200V 2kW样机。经实验验证，电流总谐波畸变率低至2%，功率转换效率高达90%。此外，一台三相样机也验证了93%的转换效率。

The aim of this project is to develop a solar-power conditioner without using any ac inductor or EMI filter by using diode-clamped linear amplifiers as the main power circuit The diode-clamped linear amplifier consists of series-connected MOSFETs, the source terminal of which is damped by dc-voltage levels. This configuration is similar to diode-clamped multi-level inverters. A general-used diode-clamped multi-level inverter uses only n-channel devices in general. On the other hand, the diode-clamped linear amplifier, however, uses complimentary power MOSFETs, p-channel and n-channel devices, as the power devices. The diode-damped linear amplifier makes it possible to provide a sinusoidal output voltage to the ac loads without any ac inductors or filter, just like a conventional linear amplifier. One of the series-connected MOSFETs acts in an active-state of the operating region. The other MOSFETs work in on-states or off-states, resulting in a great reduction of the power loss caused by the operation in the active -state.This project has developed a new current control method and current control circuit for the diode-clamped linear amplifier at first. Principle and performance have been verified by experiments using twelve-series diode-clamped linear amplifier. As a result, the developed circuit showed an accurate current control performance and a low current ripple under both normal load condition and a short-circuit condition. Next, the developed circuit has been implemented into a single-phase 200-V 2-kW prototype of an ac utility-interfaced solar power conditioner using two twelve-series diode-clamped linear amplifiers and a dc-voltage balancer. The experimental verified a current total harmonic distortion as low as 2% and power conversion efficiency as high as 90%. Moreover, a three-phase prototype also examined and demonstrated 93% conversion efficiency.