Phase-Shifted Full-Bridge DC-DC Converter for Low-Voltage Energy Transfer
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Solution Overview
Problem
DC-DC converters with phase-shifted full-bridge topology are limited by the transformer's transformation ratio, restricting energy transmission to below a certain voltage threshold, where the primary side voltage must be greater than the product of the transformation ratio and secondary voltage.
Innovation Solution
Incorporating an additional transformer with a series inductance on the secondary side and a switching element with a diode in forward direction, allowing energy transmission from the primary side to the secondary side even when the primary side voltage is below the threshold, and enabling partial discharge of a DC-link capacitor to a safe voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transformer with fixed transformation ratio is used in a phase-shifted full-bridge DC-DC converter, then the converter structure is simple and reliable, but the voltage range for energy transmission is restricted
Solution Approach 1:
The patent divides the single transformer into two separate transformers: a first transformer for high-voltage to medium-voltage conversion, and a second transformer for medium-voltage to low-voltage conversion. This segmentation allows each transformer to operate within its optimal voltage range, extending the overall adaptability of the DC-DC converter while maintaining reliable isolated full-bridge topology in each stage
Solution Approach 2:
The patent implements a nested transformer configuration where the second transformer is electrically coupled to the secondary side of the first transformer. The primary side of the second transformer is arranged between the second full-bridge circuit and the output terminal, creating a cascaded transformation structure that enables extended voltage range operation while preserving the simplicity of standardized full-bridge circuits at each stage
2Adaptability or versatility
If the primary side voltage must be greater than the product of transformation ratio and secondary voltage, then the transformer operates within safe limits, but energy transmission is limited below a certain voltage threshold
Solution Approach 1:
By segmenting the voltage transformation into two stages with separate transformers, the patent allows the first transformer to handle high-voltage to medium-voltage conversion under safe operating conditions, while the second transformer handles medium-voltage to low-voltage conversion. This segmentation enables energy transmission below the traditional voltage threshold while maintaining safe operating limits for each individual transformer
Solution Approach 2:
The patent introduces a medium-voltage intermediate stage between the high-voltage primary side and the low-voltage secondary side. The first transformer acts as an intermediary converting high voltage to medium voltage, and the second transformer further converts medium voltage to low voltage. This intermediary approach enables safe operation of each transformer within its voltage limits while achieving extended energy transmission capability
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 extended topology enables energy transmission beyond the traditional voltage limitations, increases system efficiency by utilizing stored energy in the DC-link capacitor, and eliminates the need for additional discharge circuits, reducing complexity and costs.
Implementation Method 1
a first transformer (T1), a first full-bridge circuit (10), a second full-bridge circuit (20) and a second transformer (T2). The primary side of the first transformer (T1) is connected at a terminal to a first node of the first half-bridge of the first full-bridge circuit (10)
Implementation Method 2
a series circuit comprising the secondary side of the transformer, a first switching element (S1) and a first diode (D1). In particular, the first diode (D1) is arranged between the first terminal element (A2-1) and the second terminal element (A2-2) of the second terminal (A2) of the DC-DC converter in the forward direction
Implementation Method 3
a first switching element (S1) and a first diode (D1). By closing of the switching element, the secondary side of the additional transformer can be charged. By opening of the switching element, the energy is transmitted from the secondary side of the additional transformer to the primary side
Implementation Method 4
the method comprises a step for charging a secondary side of a transformer, wherein the transformer is arranged as series inductance on the output side at the DC-DC converter. In addition, the method comprises a step for discharging the electrical energy stored in the secondary side of the transformer via the primary side of the transformer
Data Source
AI summary
The present invention relates to a circuit arrangement and to an actuating method for a DC voltage converter, in particular a DC voltage converter with phase-shifted full-bridge topology, wherein power can also be transmitted from the primary side to the secondary side when the electrical voltage on the primary side undershoots the product of the electrical voltage on the secondary side and the transmission ratio of a transformer in the DC voltage converter. In this way, for example, a capacitor on the primary side of the DC voltage converter can be discharged to a safe, low voltage level.