DC-DC Converter Full-Bridge Soft Switching Control
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Solution Overview
Problem
Existing DC-DC converters require complex circuit configurations and control methods for zero voltage switching (ZVS) operations, complicating productivity and cost reduction.
Innovation Solution
A DC-DC converter design incorporating a first and second full-bridge circuit with a transformer and inductance component, controlled by a circuit that fixes switching frequency and adjusts voltage output periods to enable ZVS operations with simple control, reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power detection and duty adjustment control are implemented to achieve ZVS operations, then switching losses are reduced and high-efficiency power transfer is achieved, but circuit configuration complexity increases and productivity decreases
Solution Approach 1:
The patent applies self-service by utilizing the inherent parasitic capacitance of switching elements and the natural inductor current to automatically achieve ZVS conditions. The system uses the existing circuit components' characteristics (parasitic capacitance and inductance) to generate the necessary soft-switching conditions without requiring external detection circuits or complex control mechanisms. The inductor current naturally charges/discharges the parasitic capacitance to enable zero-voltage switching.
Solution Approach 2:
The patent extracts and eliminates the power detection function and duty adjustment control mechanism from the system. By removing these complex control elements, the invention achieves ZVS operations through simple fixed-frequency switching control, thereby reducing circuit complexity while maintaining switching loss reduction benefits.
2Loss of energy
If power detection and duty adjustment control are implemented to achieve ZVS operations, then switching losses are reduced, but control complexity increases
Solution Approach 1:
The control system serves itself by using the natural electromagnetic characteristics of the circuit components. The parasitic capacitance and inductor current automatically interact to produce ZVS conditions, eliminating the need for external power detection and duty adjustment control.
Solution Approach 2:
The patent removes the complex power detection and duty adjustment control subsystems, retaining only simple fixed-frequency switching control. This extraction of unnecessary control elements simplifies the control methodology while preserving the energy efficiency benefits of ZVS operations.
3Power
If switching frequency is increased to improve power transfer efficiency, then power transfer efficiency increases, but switching losses increase
Solution Approach 1:
The patent changes the switching mode from hard switching to soft switching by utilizing ZVS operations. This parameter change in the switching characteristic allows the system to operate at fixed frequency without incurring increased switching losses, as the voltage across switching elements is zero during switching transitions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for easy implementation of ZVS operations, reducing switching losses and heat generation in electrical devices, while maintaining high-efficiency power transfer without increasing switching frequency.
Implementation Method 1
a transformer (T) including a first winding (n1) and a second winding (n2), wherein the first winding (n1) is connected to the first full-bridge circuit (10), the second winding (n2) is connected to the second full-bridge circuit (20) and magnetically coupled to the first winding (n1)
Implementation Method 2
an inductance component (L) connected in series with the first winding (n1) or the second winding (n2)
Implementation Method 3
four switching elements (Q11 to Q14) that include a capacitor (C11 to C14)
Data Source
AI summary
A DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer and an inductor. A control circuit performs soft switching of each switching element in the first full-bridge circuit and the second full-bridge circuit. An inductor current flowing through an equivalent inductor at a time of switching of turning on or off each switching element is greater than or equal to a threshold current, the equivalent inductor being equivalent to the transformer and the inductor. The control circuit outputs predetermined power by changing a voltage output period of the first full-bridge circuit and a voltage output period of the second full-bridge circuit while fixing the switching frequency and keeping a polarity inversion period at a value greater than or equal to a fixed value, the polarity inversion period being a period in which the output of the second full-bridge circuit and the output of the first full-bridge circuit have reverse polarities. This enables performing ZVS operations by simple control and reducing switching losses.