アジア地域の空調機用PMSMドライブ向けAC-AC変換器の研究

Abstract

In recent years, the market for air conditioners in emerging Asian countries such as India and Vietnam has been expanding. Although on-off type air conditioners have been the mainstay of the market, various manufacturers have developed high-efficiency products using inverters and permanent magnet synchronous motors (PMSM), and the ratio of inverters in Japan, China, Europe, and Oceania is increasing. On the other hand, in emerging regions such as Asia, the quality of the power supply is poor, causing frequent power outages as well as instantaneous voltage fluctuations and voltage drops. In addition, high-efficiency operation is required for power converters. This is because there is an efficiency index called APF (Annual Performance Factor) in the performance index of air conditioners, and these performances are directly related to the performance of air conditioners and even to the sales of products. Generally, an AC/DC converter is used to obtain the DC power necessary for the inverter that drives the motor from the AC power supplied to the air conditioner. AC/DC converters that have a function of suppressing harmonics of the input system current in addition to the power conversion function are called PFC (Power Factor Correction) converters in particular. In this study, we propose a partial switching method based on the commonly used PI control to stop the switching operation of the power converter near the peak of the AC voltage by appropriately adjusting the DC voltage command value, thereby reducing the switching losses. This method reduces the switching loss and thus improves the efficiency of PFC converters.