Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title High-efficiency and Slim-type Voltage Balanced 3-level Buck Converter
Authors June-Bong Jeong ; Chan-Gyu Kim ; Ka-San Ha ; Won-Myoung Woo ; Jeong-Il Kang ; Sang-Kyoo Han
Page pp.154-160
ISSN 1229-2214
Keywords 3-level buck converter; High efficiency; High power density; Voltage mode control; Slim converter.
Abstract The 3-level buck converter features half the switch voltage stress of the conventional synchronous buck converter. The operating frequency of the output inductor is also twice the switching frequency. The slope of the inductor current can be reduced as well due to the flying capacitor voltage, which can greatly reduce the size of the output inductor. Therefore, the 3-level buck converter can achieve high efficiency and high power density. The flying capacitor voltage must be half the input voltage to achieve the abovementioned strength. Most conventional control schemes for the voltage balance of the flying capacitor adopt a peak or valley current mode control method using real-time current sensing. Therefore, the control algorithm is complicated, and high performance and expensive digital controller is required. This study proposes an independent two-loop voltage mode control scheme that can guarantee the flying capacitor voltage to be half of the input voltage. The proposed control scheme can be simply implemented without current detection and does not require complicated control algorithms. Thus, simple and low-cost micro controller can be used. Experimental results from a rated prototype of 500 W are provided to verify the performance of the proposed control scheme.