Research On New Sinusoidal Resonant Driver For Synchronous BUCK Converter

With the continuous development of portable devices, small volume and highefficiency have become the continuously pursue of switching power supply field.Raise switch frequency can reduce the size and weight of switching power supply,but at the same time the loss of the switch tube increased dramatically, especiallythe gate drive loss will growe linearly with the raise of switch frequency. Useresonant gate drive circuit replace the traditional square wave drive circuit can solvethe problem between high switch frequency and high efficiency, this paper intents todesign a new type of sinusoidal resonant drive circuit which applicable tosynchronous BUCK circuit.This paper comparative analysis the resonant gate driver and traditional squarewave drive, detailed introduces the characteristics of sinsoidal resonant gate driverand discuss its advantages under the condition of high switching frequency. Inaddition, for the characteristics of synchronous BUCK circuit, finally adopt twoseries transformer get two complementary sinusoidal drive voltage, solve theproblem of high side drive. Because the driving voltage is sine wave, so the drivecircuit structure become simplitily by eliminating the complex dead zone controlcircuit. Furthermore, according to the characteristics of the sinusidal resonant gatedrive circuit, this paper adopt the voltage hysteresis “ON-OFF” closed-loop controlcircuit, solve the problem of duty ratio non-ajustable and improve the dynamicresponse at the same time. Synchronous BUCK circuit final work at at6MHz switchfrequency, reduce the size and weight of passive devices.Finally, use simulation and experiment to test and verify the circuit. Simulationand experimental results show that: when the switching frequency is6MHz, theinput voltage is15-30V, the output voltage is5V and output current is2A, theoverall efficiency of circuit can reach more than85%, output voltage grain wavepeak is less than50mV.