Self-Adaptive Current Control for DAB DC-DC Converters
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Solution Overview
Problem
Dual-active-bridge (DAB) DC-DC converters experience high transformer currents due to mismatched voltage conversion ratios and transformer turns ratios, leading to inefficiencies and potential component stress, which existing phase-shift control methods may not adequately address, especially under varying environmental conditions.
Innovation Solution
A self-adaptive current control system for DAB DC-DC converters that uses a current sensor to iteratively adjust inner phase-shift angles based on real-time transformer current measurements, reducing the RMS current value without requiring precomputed analytical expressions or simulations, and adapts during operation to minimize transformer current irrespective of power levels and circuit parameter variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phase-shift control methods are used to control DAB DC-DC converters, then power transmission is enabled, but transformer RMS current becomes excessively high due to mismatched voltage conversion ratios and transformer turns ratios
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the actual transformer current and compares it with the optimal current value calculated from the quadratic function. Based on this feedback, the controller dynamically adjusts the phase-shift angles to minimize transformer current while maintaining power transmission, thereby resolving the contradiction between power transmission capability and excessive current losses.
Solution Approach 2:
The patent changes the control parameters from fixed phase-shift angles to dynamically adjustable angles derived from a quadratic function of transformer current. By expressing phase-shift angles as functions of current parameters and optimizing these parameters through the quadratic relationship, the system achieves minimum transformer current while maintaining effective power transmission.
2Ease of operation
If precomputed analytical expressions or simulations are used for phase-shift control, then control strategy can be determined, but the system cannot adapt to varying environmental conditions and circuit parameter variations
Solution Approach 1:
The patent transitions from static precomputed control strategies to dynamic real-time optimization. The quadratic function relating transformer current to phase-shift angles is evaluated continuously during operation, allowing the controller to adapt to changing environmental conditions and circuit parameters. This dynamic approach maintains ease of operation through a systematic method while achieving full adaptability to varying conditions.
Solution Approach 2:
The system performs self-optimization by using its own measured transformer current to calculate the optimal phase-shift angles through the quadratic function. The controller automatically adjusts control parameters based on real-time system state without requiring external intervention or precomputed data, enabling both ease of operation and adaptability to varying conditions.
3Adaptability or versatility
If voltage conversion ratio is mismatched with transformer turns ratio, then converter can operate with flexible voltage levels, but transformer current increases causing component stress and inefficiency
Solution Approach 1:
The patent changes the phase-shift angle parameters dynamically based on the actual transformer current measured during operation. By using a quadratic function to determine optimal phase-shift angles that minimize current for any given voltage conversion ratio, the system maintains flexible voltage operation while preventing excessive component stress through continuous current optimization.
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
The self-adaptive current control effectively reduces and converges the transformer current to a minimum value, enhancing efficiency and stability across varying conditions without reliance on precomputed data, thus addressing the inefficiencies and stress associated with mismatched voltage conversion ratios.
Implementation Method 1
an isolated DC-DC converter can be used to interface a low-voltage battery to a high-voltage battery or a high-voltage DC bus
Implementation Method 2
a first H-bridge (H1) structured to convert a first direct current (DC) voltage (V1) to a first alternating current (AC) voltage applied on the primary winding
Implementation Method 3
a second H-bridge (H2) structured to convert an AC voltage on the secondary winding to a second DC voltage applied on a load
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3
AI summary
The present disclosure relates to electric converters and methods of controlling the same. One dual-active-bridge direct current to direct current (DC-DC) converter includes a transformer having a primary winding and a secondary winding, a first H-bridge connected to the primary winding, a second H-bridge connected to the secondary winding, and a current sensor structured to measure a current of the transformer. The first H-bridge includes a plurality of switch devices. The second H-bridge includes a plurality of switch devices. The dual-active-bridge DC-DC converter further includes a controller configured to control an on/off state for each of the plurality of switch devices of the first H-bridge and the plurality of switch devices of the second H-bridge based at least in part on the current of the transformer measured by the current sensor.