EV Battery Pulse Heating via Bidirectional DC-AC Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium iron phosphate batteries in electric vehicles face challenges in low temperature environments, where internal resistance increases, making charging difficult.
Innovation Solution
A power system for electric vehicles that includes a bidirectional DC-DC module, a bidirectional DC-AC module, and a control module to manage temperature by charging and discharging the battery in a pulse mode when it's low, thereby heating it and enabling normal charging and discharging when the temperature rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium iron phosphate battery is used as power battery, then high discharge rate and long service life are achieved, but charging difficulty occurs in low temperature environment
Solution Approach 1:
The system performs preliminary heating of the battery before charging by controlling the battery to discharge first, which generates heat through internal resistance. This preliminary action raises the battery temperature to a suitable range for charging, preventing the charging difficulty that would occur in low temperature environments.
Solution Approach 2:
The system uses periodic charge-discharge cycles to heat the battery. The battery alternates between discharging (generating heat) and charging (storing energy), with multiple cycles performed until the temperature reaches the predetermined threshold. This periodic action efficiently raises temperature without continuous energy input.
2Ease of operation
If battery heating is implemented in low temperature, then charging capability is improved, but energy consumption increases
Solution Approach 1:
The system uses the battery's own discharge process to generate heat for heating, rather than requiring an external heating device. The battery discharges through its internal resistance, converting electrical energy to thermal energy, thus heating itself. This self-service approach minimizes additional energy consumption while improving charging capability.
Solution Approach 2:
The system converts the harmful effect of internal resistance (which causes energy loss and heat generation) into a beneficial effect. In low temperature, the high internal resistance that normally hinders charging is utilized to generate heat through controlled discharge, raising the temperature to enable charging. The previously harmful heat generation is now deliberately used as a heating source.
3Temperature
If pulse mode charge-discharge is used to heat battery, then temperature increases efficiently, but charging time may be extended
Solution Approach 1:
The system performs only the necessary number of charge-discharge cycles to reach the predetermined temperature threshold, rather than continuously cycling. Once the temperature is sufficient for charging, the pulse mode heating stops and normal charging begins. This partial action approach raises temperature efficiently without unnecessarily extending the overall charging time.
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 allows for efficient and prompt charging of electric vehicle batteries, reducing charging time and maintaining low energy consumption while ensuring high reliability and low costs.
Implementation Method 1
control the power battery to charge and discharge in a pulse mode so as to heat the power battery when the temperature of the power battery is lower than a predetermined temperature
Data Source
AI summary
A power system for an electric vehicle, an electric vehicle and a method for charging a power battery are provided. The power system includes: a power battery (10); a charge-discharge socket (20); a bidirectional DC-DC module (30); a driving control switch (40); a bidirectional DC-AC module (50); a motor (M); a motor control switch (60); a charge-discharge control module (70); a battery manager (108); and a control module (80) configured to control the driving control switch (40), the motor control switch (60) and the charge-discharge control module (70) so as to control the power system to enter a charge-discharge mode, and to control the power battery (10) to charge and discharge in a pulse mode so as to heat the power battery (10) when the temperature of the power battery (10) is lower than a predetermined temperature.