Switching Circuit Designing for High-Power Synchronous Buck Converters: An Experimental Approach

Mazdak Ebadi ¹ ( Department of Electrical Engineering- Arak University, Arak, Iran )
Mohammad Amin Bahramian ² ( Department of Electrical Engineering- Arak University, Arak, Iran )
Ali Asghar Ghadimi ³ ( Department of Electrical Engineering- Arak University, Arak, Iran )

Submited date : 2023-05-08 Accepted date : 2023-08-19

Keywords: Buck converter, Dead-time control, Soft Start-up, High-power,

Abstract :

Non-isolated buck converters are well-known solutions for producing controllable DC voltage at medium and high-power levels. Meanwhile, synchronous converters have received a lot of attention due to the non-dependence of the voltage conversion ratio on the load and the continuity of the inductor current. But the switching of these converters takes place at higher power levels at lower frequencies. For this reason, the switching circuit must work with a higher dead time. In this article, an analog application circuit design without the use of a microcontroller is presented for the switching of the synchronous buck converter, which, while ensuring that pulses are not sent to the keys at the same time, the amount of dead time can be It provides a setting that can be changed according to the voltage level and current of the circuit. After analyzing the conditions at the moment of switching on and off of the circuit, it was found that at the moment of switching off, a destructive transient current is applied to the keys, which this article solves this issue by using two fast SSR relays in the path of the input signal to the gate module. The driver suggests that it has been tested on a prototype device. This article also mentions the requirements of the switching circuit by analyzing the conditions of the moment when the circuit is turned on and off, so that the transient damaging current does not pass through the IGBT. The results of experimental tests on a 15 kW synchronous buck DC/DC converter with an output of 300 V 50 amps show that the well-designed switching circuit creates an adjustable dead time of up to 6 microseconds in the switching of this converter and the continuity conditions It has provided the inductor current both in no load and under load. Also, the proposed method has well removed the transients of the circuit turning on and off.

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