Active power decoupling回路を用いたコンバータの最適化とロバスト制御に関する研究

As the use of electrical energy increases, the range of use of electric energy con-version devices is expanding. In particular, automobiles that have used internal combustion engines have been replaced by electric transducers and motors. Un-like in the past when thermal power generation and nuclear power generation have accounted for the majority of electric power production, more stable and environmentally friendly wind power and solar power generation are increasing. These devices require converters that effectively convert various types of energy into electrical energy. Efficiency, miniaturization and stability of these power con-verters have been important research topics. Recently, many researchers have been studying increasing reliability and life expectancy. The life expectancy of ac-tuators such as solar panels and light-emitting diodes(LEDs) has been increased due to the development of material technologies. However, power conversion de-vices have limitations in increasing lifespan due to manufacturing cost and failure rate increase. AC / DC converters require large capacitors to smooth the ripple power generated from the power source. Electrolytic capacitors(E-Caps.) have been used in many applications as they have advantages in volume and price when compared with other types of capacitors. However, there is a problem that it is susceptible to temperature and ripple current due to the structure including high equivalent series resistance(ESR) and electrolyte. This has the shortest lifespan of the components and limits the life of the power inverter. Therefore, in order to increase the lifetime of the electric energy conversion device, it is necessary to replace it with another types of capacitor having high reliability. In recent years, research has been conducted to replace E-Caps with film capac-itors having relatively long lifetime and high reliability in order to improve the lifetime and failure rate of power conversion devices. Film capacitors have a relatively long lifetime compared to E-Caps due to their low ESR, self-healing and stable structure. However, there are problems that it is difficult to apply to actual products due to the large volume and high price compared to the same capacity. To solve this problem, it is necessary to reduce the capacity of the film capacitor. Single-phase AC/DC converters are approaching two ways: capacitor-less inverter control and active power decoupling(APD) method. In the case of capacitor-less inverter control, power is controlled at the inverter side so that the motor behaves like a resistive load. This method has the advantage that power factor correction can be performed using a small-capacity film capacitor without the need for other auxiliary circuits. However, there is a problem that demagnetization may occur due to a high phase current of the inverter, deterio-rated efficiency, and noise may be generated. The APD method actively removes power ripple using an auxiliary circuit. This makes it possible to remove power ripple even with a small-capacity film capacitor. However, there is a problem that the use of the auxiliary circuit increases the manufacturing cost and in-creases the uncertainty due to the increased complexity, which makes it difficult to ensure stability. In this study, we propose a solution to the problem of increased manufactur-ing cost and stability of existing APD system. The number of components was optimized by designing the parts used in the converter circuit and the APD circuit. In addition, the voltage stress of the parts can be reduced, making it possible to use parts with lower rated voltage, thereby reducing manufacturing costs. In addition, the converter and the APD circuit are modularized through the commonization so that it can be expanded easily according to the required capacity of the product. This enabled us to take advantage of volume benefits. In addition, we proposed a way to implement the APD function without us-ing additional components by changing only the control method of the existing bridge-less single ended primary inductor converter(SEPIC). Sliding mode con-trol(SMC) strategy and Lyapunov function based control are used to solve the problem of control instability of the model. Because the APD circuit uses a large number of passive elements, the process error of each passive element increases the uncertainty of the model. The proposed control scheme always guarantees stability and performance even in the presence of this uncertainty. In addition, we proposed a parameter selection criterion based on the control theory, and it is possible to design a controller which can guarantee the target performance easily. All proposed circuit and control strategies have been validated through simulation using MATLAB / SIMULINK and experiment using prototype