EV Battery Thermal Control Using Charger Heat During V2G
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Solution Overview
Problem
Existing battery temperature control devices for electric vehicles participating in V2G struggle to efficiently heat batteries in low temperature environments, leading to potential malfunctions during charge and discharge operations due to temperature limitations and inefficient heat transfer between batteries and power converters.
Innovation Solution
A battery temperature control device that includes a battery cooling circuit, a power converter cooling circuit, and a four-way valve allowing connection between these circuits, enabling efficient heat transfer by circulating refrigerant from the power converter cooling circuit to the battery cooling circuit when the battery temperature is below a predetermined threshold, thus maintaining optimal operating temperatures for both the battery and power converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature rise control is performed before V2G execution by circulating refrigerant in a single-loop temperature adjustment circuit, then the battery temperature can be raised to the predetermined range, but the time required to execute V2G increases due to waiting for temperature rise
Solution Approach 1:
The patent merges the temperature adjustment circuit with the charge/discharge circuit by allowing the refrigerant to flow through both the battery and the charge/discharge device. This integration enables simultaneous temperature management and power conversion operations, eliminating the need for separate pre-heating phases and reducing V2G execution delay while maintaining battery reliability.
Solution Approach 2:
The charge/discharge device serves dual functions: it performs power conversion and simultaneously acts as a heat source to warm the battery when needed. By utilizing the heat generated during power conversion operations to maintain battery temperature, the system eliminates the need for dedicated pre-heating time, allowing V2G to execute promptly while ensuring battery reliability through self-generated thermal management.
2Loss of energy
If a single-loop temperature adjustment circuit is used to heat the battery, then the structure remains simple, but the efficiency of heat transfer from the charge/discharge device to the battery is insufficient
Solution Approach 1:
The patent combines the temperature adjustment circuit and charge/discharge circuit into an integrated system where the refrigerant flows sequentially through the battery and the charge/discharge device. This merging creates efficient thermal coupling between the two components, maximizing heat transfer from the charge/discharge device to the battery while maintaining a relatively simple single-loop structure that does not require complex multi-circuit configurations.
3Reliability
If the battery temperature is maintained in a predetermined range through pre-heating before V2G, then proper charge and discharge can be achieved, but the battery cannot respond promptly to charge and discharge requests from the power system in low temperature environments
Solution Approach 1:
The system uses the heat generated during power conversion in the charge/discharge device to maintain battery temperature in real-time. This self-heating capability allows the battery to respond immediately to V2G requests without requiring pre-heating, as the thermal management occurs concurrently with power operations, ensuring both charge/discharge reliability and rapid response speed.
Solution Approach 2:
The refrigerant circulation and heat transfer occur continuously during V2G operations rather than as a separate pre-processing step. This continuous thermal management ensures the battery remains within the optimal temperature range throughout the charge/discharge process, maintaining reliability while enabling immediate response to power system requests without interruption or delay.
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 configuration allows for stable execution of V2G operations even in low temperatures by efficiently heating the battery and preventing output limit exceedance, ensuring proper charge and discharge without battery malfunction.
Implementation Method 1
transfer the heat energy of the bidirectional charger to the battery via the refrigerant circulating in the temperature adjustment circuit
Implementation Method 2
circulating a refrigerant in the temperature adjustment circuit
Data Source
AI summary
The disclosure provides a battery temperature control device of an electric vehicle capable of efficiently heating a battery for vehicle driving while executing V2G in a low temperature environment. A battery temperature control device of an electric vehicle controls the temperature of a battery of the electric vehicle, and the electric vehicle participates in V2G which allows bidirectional power exchange between the battery for vehicle driving mounted on the electric vehicle and a power system. When an aggregator on the power system side starts execution of V2G by transmitting to an ECU a start instruction for the charge and discharge of the battery, the ECU controls a four-way valve to connect a battery cooling circuit and a charger cooling circuit when a battery temperature is less than a predetermined temperature.