Circuit Arrangement for Electric Drive Energy Decoupling
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Solution Overview
Problem
Current energy storage systems in electric vehicles face inefficiencies due to limitations in power and energy density, leading to short driving ranges and high energy conversion losses, especially when combining different energy sources like double-layer capacitors and batteries, which result in deteriorated system efficiency and increased complexity in controlling state of charge and self-discharge behaviors.
Innovation Solution
A circuit arrangement that allows for the decoupling of different energy sources, including batteries and capacitors, using a switch with a filter and pre-charge circuit, enabling temporary actuation and separation of energy sources to optimize energy supply to an electric drive, while preventing circulating currents and energy backflow, thereby enhancing system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If different energy stores (double-layer capacitor and battery) are connected in parallel to increase power and energy density, then the driving range and power capability are improved, but circulating currents occur due to voltage asymmetry causing deterioration in system efficiency
Solution Approach 1:
A DC-DC converter is introduced as an intermediary device between the double-layer capacitor and battery. This converter controls the energy exchange between the two different voltage levels, preventing direct parallel connection that would cause circulating currents. The converter acts as a mediator that manages power flow based on state of charge, ensuring efficient operation while maintaining the benefits of both energy storage types.
2Adaptability or versatility
If different energy stores are connected in series to balance voltage levels, then the system can operate with different voltage levels, but additional controlling effort is required for state of charge management and self-discharge compensation
Solution Approach 1:
The DC-DC converter serves as an intermediary that simplifies the control architecture by providing automated state of charge management. Rather than requiring complex series connection control, the converter handles voltage level adaptation and energy balancing automatically based on predefined control strategies, reducing the overall system complexity while maintaining versatility.
Solution Approach 2:
The system dynamically changes operating parameters (voltage levels, power distribution, state of charge thresholds) through the DC-DC converter to adapt to different driving conditions. This allows the system to optimize performance across various scenarios without requiring manual intervention or complex control logic.
3Speed
If double-layer capacitors are used to achieve excellent acceleration values with low storage weight, then the power density and acceleration performance are improved, but the electric driving range is limited to only a few hundred meters
Solution Approach 1:
The patent combines double-layer capacitors and batteries into a hybrid energy storage system. The double-layer capacitor provides high power for acceleration, while the battery supplies sustained energy for extended range. This merging of complementary technologies allows the system to achieve both excellent acceleration performance and extended electric driving range that neither component could provide alone.
4Duration of action of moving object
If batteries are used to achieve several kilometers of electric driving, then the energy density and driving range are improved, but energy conversion losses increase significantly at higher power conversions
Solution Approach 1:
The power delivery function is segmented between two energy storage devices: the double-layer capacitor handles high-power transient demands (acceleration, regenerative braking), while the battery provides steady-state power for sustained driving. This segmentation allows each component to operate in its optimal efficiency range, minimizing overall energy conversion losses while maintaining extended driving range.
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 approach enables efficient energy management by allowing different energy sources to supply an electric drive based on their properties, improving range and efficiency, reducing energy conversion losses, and simplifying the control of energy storage systems, thereby enhancing the overall performance and longevity of electric vehicle powertrains.
Implementation Method 1
with a pre-charge circuit that couples the battery and capacitor source
Implementation Method 2
with at least one filter
Data Source
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AI summary
The invention relates to a circuit arrangement for supplying an electric drive to which at least two electrical energy sources can be connected, wherein at least one of the at least two electrical energy sources supplies the electric drive at least intermittently by means of at least one actuator, and wherein at least one electrical energy source can be disconnected from the electric drive by means of a switch. The invention further relates to a method for operating the circuit arrangement, and to a motor vehicle comprising the circuit arrangement.