Resonant DC/DC converter and its control method

Abstract

The invention discloses a resonance direct current / direct current converter and control method, it adjusts output voltage by changing conducting frequency of input switch of the resonance circuit, adjusts the shift angle of said switch according to feedback signal of load circuit to extend the output range of voltage of the resonance circuit. The invention also provides structure of the resonance direct current / direct current converter with said method. The advantages of the invention are following: adopting frequency modulation and frequency modulation+ shift phase control mode to control the resonance direct current / direct current converter, using frequency modulation when operating frequency of power source is low, using frequency modulation+ shift phase when operating frequency of power source is too high, the problem of resonance converter is resolved, that is problem of high operating frequency and big spoilage, and the output voltage adjustment capability of resonance circuit increased greatly, the output voltage range is extended efficiently.

Description

Technical field

[0001] The invention relates to DC power conversion technology, in particular to a resonant DC / DC converter and a control method thereof.

Background technique

[0002] Miniaturization and high frequency are the development trend of power supply today, but the increase of switching frequency has brought about the problem of excessive loss of the switching tube, which cannot be solved by the traditional BUCK converter, but the resonant converter can better solve it this problem.

[0003] Taking the series resonant converter as an example, the series resonant DC / DC (DC / DC) converter adopts resonant conversion technology. Since the resonant element works in a sinusoidal resonance state, the voltage on the switching tube naturally crosses zero, which can realize zero-voltage turn-on. The loss is very small. This topology usually adopts a pulse frequency modulation (PFM) method to stabilize the output voltage by changing the operating frequency. figure 1 It ...

Examples

Embodiment Construction

[0046] A control method of a resonant DC / DC converter is to adjust the output voltage by changing the conduction frequency of the input switching tube of the resonant circuit, and also according to the feedback signal of the load circuit (obtained from the output voltage or output current sampling of the resonant converter) ) to adjust the phase shift angle of the switching tube, so that the voltage output range of the resonant circuit is expanded.

[0047] still with figure 1 Take the full-bridge series resonant circuit in the example, image 3 Curves A1~A3 in the figure are schematic diagrams of characteristic curves of output voltage Vo and frequency f with a phase shift angle of 0 degrees under different load conditions using separate PFM control mode. It can be seen that as the load is reduced, Vo tends to be flat. It is difficult to stabilize by increasing the operating frequency. image 3 The curves B1, B2, and B3 in the curves are respectively the characteristic curv...

Technical field

[0001] The invention relates to DC power conversion technology, in particular to a resonant DC / DC converter and a control method thereof.

Background technique

[0002] Miniaturization and high frequency are the development trend of power supply today, but the increase of switching frequency has brought about the problem of excessive loss of the switching tube, which cannot be solved by the traditional BUCK converter, but the resonant converter can better solve it this problem.

[0003] Taking the series resonant converter as an example, the series resonant DC / DC (DC / DC) converter adopts resonant conversion technology. Since the resonant element works in a sinusoidal resonance state, the voltage on the switching tube naturally crosses zero, which can realize zero-voltage turn-on. The loss is very small. This topology usually adopts a pulse frequency modulation (PFM) method to stabilize the output voltage by changing the operating frequency. figure 1 It ...

Examples

Embodiment Construction

[0046] A control method of a resonant DC / DC converter is to adjust the output voltage by changing the conduction frequency of the input switching tube of the resonant circuit, and also according to the feedback signal of the load circuit (obtained from the output voltage or output current sampling of the resonant converter) ) to adjust the phase shift angle of the switching tube, so that the voltage output range of the resonant circuit is expanded.

[0047] still with figure 1 Take the full-bridge series resonant circuit in the example, image 3 Curves A1~A3 in the figure are schematic diagrams of characteristic curves of output voltage Vo and frequency f with a phase shift angle of 0 degrees under different load conditions using separate PFM control mode. It can be seen that as the load is reduced, Vo tends to be flat. It is difficult to stabilize by increasing the operating frequency. image 3 The curves B1, B2, and B3 in the curves are respectively the characteristic curv...

Images