Isolated type DC/DC boost converter provided with pull-up active clamping branch and control method thereof

Abstract

The invention belongs to the field of electrical technologies and relates to an isolated type DC / DC boost converter provided with a pull-up active clamping branch and a control method thereof. On the basis of the single-end flyback-type circuit topology, the primary side of a transformer is connected in parallel with a resonant capacitor and a pull-up active clamping branch. The secondary side of the transformer is in cascade connection with a high-frequency voltage doubling circuit. The resonance oscillation occurs between the resonant capacitor and the primary side of the transformer, wherein the resonant capacitor and the primary side of the transformer are connected in parallel. In this way, the bidirectional excitation of an original circuit is enabled and the utilization rate of a magnetic core is improved. Meanwhile, the output-to-input voltage gain of the isolated type DC / DC boost converter is improved. The auxiliary switch tube and the main switch tube of the active clamping branch are the same in switching period, while the auxiliary switch tube is only turned on for a short period of time during each switching period. Therefore, the conduction loss is reduced. The soft switching of the main switch tube and the soft switching of the auxiliary switch tube are both enabled, so that the direct connection problem is avoided. Through arranging the high-frequency voltage doubling circuit in cascade connection with the secondary side of the transformer, an asymmetrical voltage outputted by the secondary-side winding of the transformer is effectively utilized. Therefore, the overall efficiency of the converter is further improved.

Description

[0001] Technical field: [0002] The invention belongs to the field of electrical technology, and relates to a new topology of an isolated DC-DC (DC-DC) boost converter and a control method thereof, in particular to an isolated DC-DC with a pull-up active clamping branch Boost converter and its control method. [0003] Background technique: [0004] The traditional isolated DC-DC boost converter topology circuit has five forms: forward type, flyback type, half-bridge type, full-bridge type, and push-pull type. Among them, the structure of the forward type and flyback type circuits is simple, Low cost and easy to control, but there are disadvantages such as one-way excitation of the transformer, easy saturation of the magnetic core, low utilization rate of the magnetic core, difficulty in increasing the power, and difficulty in realizing soft switching control; the two-way excitation of the transformer in the half-bridge and full-bridge circuits, The utilization rate of the mag...

AI Technical Summary

Problems solved by technology

[0004] The traditional isolated DC-DC boost converter topology circuit has five forms: forward type, flyback type, half-bridge type, full-bridge type, and push-pull type. Among them, the structure of the forward type and flyback type circuits is simple, Low cost and easy to control, but there are disadvantages such as one-way excitation of the transformer, easy saturation of the magnetic core, low utilization rate of the magnetic core, difficulty in increasing the power, and difficulty in realizing soft switching control; the two-way excitation of the transformer in the half-bridge and full-bridge circuits, The utilization rate of the magnetic core is high, and the power can be increased, but there is a bias problem, and the upper and lower bridge arms are easy to pass through, the circuit control is relatively difficult, and the reliability is low; the transformer of the push-pull circuit is also bidirectionally excited, and there is no direct connection between the upper and lower bridge arms problem, but there is still a magnetic bias problem, and the transformer needs to be tapped, the design is difficult, and soft switching cannot be realized

In recent years, a new circuit topology of the isolated DC-DC boost converter has emerged, that is, the active clamp flyback circuit topology. This topology circuit can realize soft switching through resonance, and has a simple circuit structure and no shoot-through problem. , low cost, easy control, etc., have been applied to the front-end circuit of solar micro-inverters, but this new topology still has one-way excitation, the magnetic core is easy to saturate, the utilization rate of the magnetic core is low, and the power is difficult to increase, etc. problem, and the auxiliary switch tube of the active clamp branch is complementary to the main switch tube, and the conduction loss of the auxiliary switch tube is relatively large, which restricts its further popularization and application

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