High step-up soft-switching converter

Abstract

This disclosure provides a high boost ratio soft-switching converter, comprising a coupling inductor, a first switch, a resonant branch, a second switch, an energy storage capacitor, a complex diode, and an output filter capacitor. The coupling inductor includes a first winding and a second winding. The first switch is electrically connected to the first winding. The resonant branch is electrically connected to the first switch and includes a resonant inductor and a resonant capacitor. The second switch is electrically connected between the resonant inductor and the resonant capacitor. The energy storage capacitor is electrically connected to the second winding. The complex diodes are electrically connected between the second winding and the energy storage capacitor. The output filter capacitor is electrically connected between these diodes and a load. The first switch is switched on at a zero-voltage state. This improves the conversion efficiency.

Claims

1. A high boost ratio soft-switching converter, comprising: a coupling inductor including a first winding and a second winding; a first switch electrically connected to the first winding of the coupling inductor; a resonant branch electrically connected to the first switch and including a resonant inductor and a resonant capacitor, the resonant inductor being connected in series with the resonant capacitor; a second switch electrically connected between the resonant inductor and the resonant capacitor in the resonant branch; an energy storage capacitor electrically connected to the second winding; a plurality of diodes electrically connected to the second winding of the coupling inductor and the energy storage capacitor; and an output filter capacitor electrically connected between the diodes and a load; wherein, The original control signal of the first switch is delayed by a preset time to form a first switch control signal. The original control signal and the first switch control signal are logically processed to form a second switch control signal, so as to control the second switch to be turned on in advance before the first switch is switched to the on state, so that the first switch is switched on in a zero voltage state.

2. The high boost ratio soft switching converter as claimed in claim 1, wherein the number of diodes is three, namely a first diode, a second diode and a third diode, wherein the first diode is electrically connected to the first winding of the coupling inductor and the resonant capacitor, the second diode is electrically connected to the resonant inductor and the second winding of the coupling inductor, and the third diode is electrically connected to the second winding of the coupling inductor and the output filter capacitor.

3. The high boost ratio soft-switching converter as described in claim 1, wherein the first switch is in the off state and the second switch is in the on state, causing the resonant capacitor to begin discharging, and the current in the resonant inductor to rise from zero, thereby forming a resonant circuit composed of the resonant inductor and the resonant capacitor, and one circuit equation of the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is an input voltage of the high boost ratio soft switching converter, D is a duty cycle of the first switch, t is the current flowing through the resonant inductor, t is the current flowing through the resonant capacitor, t is the voltage across the resonant capacitor, and t is the voltage across the resonant inductor.

4. A high boost ratio soft-switching converter as described in claim 1, wherein the second switch remains on, causing the voltage across the resonant capacitor to drop to an input voltage, and the resonant inductor and the resonant capacitor continuously form a resonant circuit. During this period, the current in the resonant inductor continuously and gradually increases, and the resonant capacitor continuously discharges. One circuit equation for the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is the input voltage of the high boost ratio soft switching converter, t is the current flowing through the resonant inductor, t is the voltage across the resonant capacitor, t is the capacitance value of the resonant capacitor, t is the inductance value of the resonant inductor, t is the derivative of the voltage across the resonant capacitor with respect to time, t is the rate of change of the current in the resonant inductor with respect to time, and t is the constant current through the first winding of the coupling inductor.

5. A high boost ratio soft-switching converter as described in claim 1, wherein the voltage across the resonant capacitor drops to a negative voltage, causing one of the diodes to conduct in the forward direction, resulting in zero voltage across the first switch, and controlling the first switch to switch from a cutoff state to a conduction state to perform the zero-voltage state switching, while simultaneously controlling the second switch to switch from a conduction state to a cutoff state, and one circuit equation of the high boost ratio soft-switching converter is: ; where, t is a time, t is an initial time, t is an end time, t is one of the input voltages of the high boost ratio soft switching converter, t is a resonant impedance, t is a constant current through the first winding of the coupling inductor, t is the current flowing through the first switch, and t is the current flowing through the resonant inductor.

6. A high boost ratio soft-switching converter as described in claim 1, wherein the first switch remains on while the second switch switches from on to off, at which time both diodes are forward-biased. To form a resonant circuit between the energy storage capacitor and the resonant inductor, the capacitance of the energy storage capacitor is chosen to be approximately the same as the capacitance of the resonant capacitor, and the resonant inductor simultaneously discharges to supply energy to the energy storage capacitor. One circuit equation for the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is an input voltage of the high boost ratio soft switching converter, t is the inductance value of the resonant inductor, t is the capacitance value of the energy storage capacitor, t is the current flowing through the resonant inductor, t is the voltage across the second winding of the coupled inductor, t is the voltage across the resonant capacitor, t is the voltage across the energy storage capacitor, t is the voltage across the first winding of the coupled inductor, N is a turns ratio of the coupled inductor, N is the derivative of the voltage across the energy storage capacitor with respect to time, and N is the rate of change of the current in the resonant inductor with respect to time.

7. The high boost ratio soft-switching converter as claimed in claim 1, wherein the first switch remains in the on state until the first switch changes from the on state to the off state, and one circuit equation of the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is the current flowing through the first switch, t is the constant current through the first winding of the coupled inductor, and t is the voltage across the resonant capacitor.

8. A high boost ratio soft-switching converter as claimed in claim 1, wherein when the first switch is switched to the off state, the current flowing through the first winding of the coupling inductor charges the resonant capacitor, causing the voltage of the resonant capacitor to gradually increase, and one circuit equation of the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is the capacitance value of the resonant capacitor, t is the derivative of the voltage across the resonant capacitor with respect to time, and t is the constant current through the first winding of the coupled inductor.

9. A high boost ratio soft-switching converter as claimed in claim 1, wherein both the first switch and the second switch remain in the off state, such that the coupling inductor and the energy storage capacitor simultaneously transfer energy to the load via one of the diodes, and one circuit equation of the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is an input voltage of the high boost ratio soft switching converter, t is the capacitance value of the resonant capacitor, t is the constant current through the first winding of the coupling inductor, t is the constant current through the second winding of the coupling inductor, t is the voltage across the resonant capacitor, and t is the derivative of the voltage across the resonant capacitor with respect to time.

10. A high boost ratio soft-switching converter as claimed in claim 1, wherein one of the diodes switches from an on state to an off state, stopping the charging of the resonant capacitor, the first switch and the second switch remain in the off state, and the coupling inductor and the energy storage capacitor continue to transfer energy to the load, and one circuit equation of the high boost ratio soft-switching converter is: ; where, t is a time interval, t is an initial time interval, t is an end time interval, t is a constant current flowing through the first winding of the coupled inductor, t is a constant current flowing through the second winding of the coupled inductor, t is the voltage across the resonant capacitor, t is one of the input voltages of the high boost ratio soft switching converter, and D is a duty cycle of the first switch.

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