Dynamic Power Distribution in Parallel DC-DC Converters
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Solution Overview
Problem
The existing charging systems for electric and hybrid vehicles face inefficiencies due to differences between identical DC-DC converters caused by dispersion, aging, and temperature variations, leading to premature aging and reduced performance over time.
Innovation Solution
A control method that characterizes the efficiencies of each DC-DC converter and adapts the power transmission accordingly, increasing the power of the more efficient converter and reducing the power of the less efficient one, without hardware modifications, to optimize overall system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two identical DC-DC converters are used in parallel to ensure galvanic isolation and system reliability, then system reliability is improved, but differences due to dispersion, aging, and temperature variations cause one converter to become less efficient over time, leading to accelerated aging and reduced overall system efficiency
Solution Approach 1:
The patent implements dynamic power distribution between the two DC-DC converters based on their real-time efficiency characteristics. The control system continuously monitors and adjusts the power transmitted by each converter, shifting more power to the more efficient converter while reducing power to the less efficient one. This dynamic adaptation resolves the contradiction by maintaining system reliability through continued parallel operation while optimizing overall efficiency to prevent accelerated aging.
Solution Approach 2:
The patent employs a feedback mechanism where the control system monitors the efficiency of each DC-DC converter and uses this information to adjust power distribution. By measuring actual performance and continuously adapting the power split based on this feedback, the system maintains optimal efficiency while preserving the reliability benefits of having two converters in parallel operation.
2Ease of operation
If power is evenly distributed between two DC-DC converters, then device complexity is reduced and operation is simplified, but the less efficient converter heats up more and ages faster, reducing its performance over time
Solution Approach 1:
The system transitions from static even power distribution to dynamic adaptive power distribution. The control method automatically adjusts the power split between converters based on their efficiency characteristics, which changes over time due to aging and operating conditions. This maintains operational simplicity from the user perspective while internally optimizing to extend converter lifespan.
Solution Approach 2:
The patent changes the operating parameters of the converters by adjusting the power transmitted by each converter. Instead of maintaining fixed equal power distribution, the system varies the power parameters dynamically based on efficiency measurements, thereby extending the operational life of the less efficient converter while maintaining overall system performance.
3Productivity
If the less efficient DC-DC converter operates at full power, then charging speed is maintained, but electrical losses increase and the converter ages prematurely
Solution Approach 1:
The patent applies partial action by having the less efficient converter operate at reduced power levels rather than full power. The control system determines the optimal power distribution where the more efficient converter handles a larger portion of the charging load, thereby reducing electrical losses and thermal stress on the less efficient converter while maintaining adequate overall charging speed through the combined output of both converters.
Solution Approach 2:
The system changes the power transmission parameter of the less efficient converter dynamically. Instead of operating at constant full power, the converter's power output is adjusted based on its efficiency characteristics, reducing electrical losses and thermal generation while maintaining system productivity through coordinated operation with the more efficient converter.
Data Source
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AI summary
The invention concerns a method for controlling a charging system of a traction battery comprising an input rectifier stage connected at the output to two capacitors connected via a midpoint, a DC-DC converter (DCDCH) being connected at the input to the terminals of one of the capacitors and another DC-DC converter (DCDCL) being connected at the input to the terminals of the other of the capacitors, the outputs of the DC-DC converters (DCDCH, DCDCL) being connected in parallel to the terminals of the traction battery, the control method comprising the steps of: - increasing (E7) the power transmitted by the converter having the highest efficiency (DCDCH) among the converters, and reducing (E7) the power transmitted by the other of the converters (DCDCL), with respect to an initial operation of the charging system.