Bidirectional DC-DC Converter Dynamic Duty Control
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Solution Overview
Problem
Existing bidirectional insulated DC-DC converters experience inefficiencies due to periods where no electric power is transferred during cycle times, reducing overall power transfer efficiency from the secondary side to the primary side of a transformer.
Innovation Solution
A bidirectional insulated DC-DC converter with a control circuit that measures voltage ratios and adjusts switching element operation periods to prevent power cancellation, ensuring continuous power transfer by calculating and controlling the ON and OFF periods of switching elements based on voltage ratios and inductance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If switching elements are controlled with fixed duty cycles for synchronous rectification, then the control is simple, but periods occur where no electric power is transferred during cycle time, reducing power transfer efficiency
Solution Approach 1:
The patent applies dynamics by transitioning from fixed duty cycle control to dynamic duty ratio adjustment. The control circuit continuously monitors voltages and calculates optimal duty ratios in real-time based on the voltage ratio n and inductance values, allowing the switching elements to adapt their operation periods to eliminate power transfer gaps while maintaining manageable control complexity through automated calculations.
Solution Approach 2:
The patent implements parameter changes by modifying the duty ratio of switching elements based on calculated parameters (voltage ratio n, inductance L1 and Lm). The control circuit adjusts the first and second periods of switching elements dynamically according to the formula dJ = n(1+L1/2Lm)−1, transforming the system from static to parameter-adaptive operation to eliminate periods with no power transfer.
2Productivity
If the duty of switching elements is increased to maintain continuous power transfer, then power transfer efficiency improves, but the complexity of control calculations increases
Solution Approach 1:
The patent implements feedback by having the control circuit continuously measure voltages VH and VL, calculate the voltage ratio n, and use this feedback to adjust the duty ratios of switching elements. The control system incorporates feedback loops that monitor power transfer status and dynamically modify switching periods based on the calculated parameters, maintaining efficiency while managing complexity through systematic feedback control.
Solution Approach 2:
The patent replaces complex manual or mechanical control adjustments with automated electronic calculations. The control circuit uses electronic computation to determine optimal duty ratios based on voltage measurements and inductance values, substituting what would otherwise require complex mechanical adjustment mechanisms with streamlined electronic parameter calculation and adjustment.
3Productivity
If switching elements are turned ON and OFF frequently to maintain continuous power transfer, then power transfer efficiency improves, but switching losses increase
Solution Approach 1:
The patent applies partial action by calculating and implementing the minimum necessary switching periods required to maintain continuous power transfer. Rather than excessive switching that would increase losses, the control circuit determines the precise first and second periods needed based on voltage ratios and inductance values, performing just enough switching action to eliminate power transfer gaps while minimizing unnecessary switching cycles and associated energy losses.
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 solution enhances power transfer efficiency by eliminating periods of no power transfer, allowing for improved energy delivery from the secondary side to the primary side of the transformer.
Implementation Method 1
a transformer (3) having a primary winding and a secondary winding... When electric power is transferred from the secondary side to the primary side of the transformer
Implementation Method 2
a secondary circuit connected to the secondary winding of the transformer and including a coil (17)... L1 denotes inductance of the coil
Data Source
AI summary
A bidirectional insulated DC-DC converter includes a transformer, a secondary circuit, and a control circuit. When electric power is transferred from the secondary side to the primary side of the transformer, the control circuit measures a first voltage on a high voltage side of the transformer and a second voltage on a low voltage side of the transformer in each cycle time. When the voltage ratio is a reference value or larger, the control circuit calculates a first period during which the control circuit turns ON the first switching element and a second period during which the control circuit turns ON the second switching element after the first period of the cycle time so that a period ratio is larger than a reference value and controls the first switching element and the second switching element based on the first period and the second period.