EV Dual Energy Storage Control for Intermediate Circuit Voltage
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Solution Overview
Problem
Existing electric vehicle systems with dual energy storage devices face challenges in efficiently managing energy distribution between rechargeable battery storage devices and double-layer capacitor devices, particularly in maintaining optimal voltage levels and preventing unintended power flows.
Innovation Solution
The implementation of a method where a first energy storage device (battery) is connected to an energy supply unit via a bidirectional converter, and a second energy storage device (double-layer capacitor) is connected directly to electrical consumers via an intermediate circuit, with a power flow from the battery to the capacitor initiated when the intermediate circuit voltage falls below a definable voltage, preventing reverse power flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the second energy storage device (double-layer capacitor) is connected directly to the electrical consumer via an intermediate circuit, then the response speed and power delivery capability are improved, but the voltage stability and energy management complexity increase
Solution Approach 1:
The system segments the energy storage function into two distinct devices: a double-layer capacitor for high-speed power delivery and a rechargeable battery for stable energy supply. This segmentation allows each component to specialize in its optimal function, with the capacitor handling transient power demands and the battery providing baseline energy, thereby managing complexity through functional division.
Solution Approach 2:
The bidirectional converter unit acts as an intermediary between the rechargeable battery and the intermediate circuit. It mediates power flow by converting voltage levels and controlling charge/discharge cycles, ensuring the battery only charges the capacitor when voltage conditions are optimal. This intermediary component manages the complexity of interfacing two different energy storage technologies.
2Reliability
If power flow from the first energy storage device to the second is allowed only when intermediate circuit voltage falls below a definable voltage, then the second energy storage device maintains minimum voltage levels, but the power flow control complexity increases
Solution Approach 1:
The system implements feedback control by continuously monitoring the intermediate circuit voltage and using this information to control the bidirectional converter unit. When the voltage falls below the definable threshold, the converter activates to transfer power from the battery to the capacitor, restoring voltage levels. This feedback mechanism ensures voltage stability while providing clear, rule-based control logic.
Solution Approach 2:
The system changes the operating parameter (power flow direction) based on the voltage threshold condition. When the intermediate circuit voltage drops below the definable voltage, the bidirectional converter reverses its normal operation to charge the capacitor from the battery. This parameter-based control simplifies the decision-making process compared to continuous complex algorithms.
3Power
If the second energy storage device is dimensioned for short-term power peaks, then the power delivery capability is improved, but the total energy capacity is reduced
Solution Approach 1:
The system merges two different energy storage technologies with complementary characteristics: a double-layer capacitor optimized for high power, short-duration discharge and a rechargeable battery optimized for high energy, long-duration discharge. By combining these devices in a hybrid architecture, the system achieves both high power delivery capability (from the capacitor) and sufficient total energy capacity (from the battery), resolving the trade-off between power and energy.
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 ensures that the second energy storage device is always charged to a minimum definable voltage, providing consistent power to electrical consumers while preventing the battery from recharging the capacitor, thus optimizing energy management and extending the lifespan of the energy storage devices.
Implementation Method 1
The first energy storage device is connected to the energy supply unit via a bidirectional converter unit, and the second energy storage device is connected to the energy supply unit. There is a first power flow from the first energy storage device to the second energy storage device if the intermediate circuit voltage falls below a definable voltage
Implementation Method 2
a second energy storage device which is arranged, e.g., as a double-layer capacitor device and/or which can be charged and discharged, e.g., faster than the first energy storage device
Data Source
AI summary
In a method for operating an electric vehicle, including a first energy storage device (e.g., a rechargeable battery storage device), a second energy storage device (e.g., a double-layer capacitor device), an energy supply unit which provides energy, for charging the first and/or second energy storage device, and a first electrical consumer connected to the second energy storage device via an intermediate circuit, the first energy storage device is connected to the energy supply unit via a bidirectional converter unit, the second energy storage device is connected to the energy supply unit, a first power flows from the first energy storage device to the second energy storage device if an intermediate circuit voltage falls below a definable voltage, and a second power flow from the second to the first energy storage device is prevented.