Battery Pack Heating Film Power Control Under Bus Voltage Fluctuation
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Solution Overview
Problem
Existing battery heating solutions using heating films are prone to damage due to excessive operating power caused by voltage fluctuations between the positive and negative direct current buses, leading to safety risks and reduced efficiency.
Innovation Solution
A controller adjusts the duty cycle of a pulse signal to manage the operating power of the heating film by connecting it in series with a switching transistor between the buses, reducing the duty cycle when voltage exceeds a threshold and increasing it when voltage is below the threshold, and includes safety mechanisms to detect and isolate faulty transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the heating film is directly connected between the positive and negative direct current buses, then the heating film can operate at full power, but the operating power becomes excessively high when voltage increases, causing damage to the heating film
Solution Approach 1:
A switching transistor is introduced as an intermediary component between the heating film and the direct current buses. The switching transistor controls the power delivery to the heating film, preventing excessive power when voltage increases while maintaining full power capability when needed. This intermediary device protects the heating film from damage.
Solution Approach 2:
The controller dynamically changes the operating parameters (duty cycle) of the switching transistor based on voltage conditions. When voltage exceeds a threshold, the duty cycle is reduced to limit power; when voltage is within normal range, the duty cycle is increased to maximize heating efficiency. This parameter adjustment resolves the contradiction between power utilization and safety.
2Productivity
If the heating film operates at high power to heat the battery efficiently, then heating efficiency is improved, but the heating film is damaged due to excessively high operating power from voltage fluctuation
Solution Approach 1:
The controller implements feedback control by monitoring the voltage between the direct current buses and adjusting the switching transistor's duty cycle accordingly. When voltage fluctuates and causes excessive power, the feedback mechanism reduces the duty cycle to protect the heating film. This closed-loop control maintains high heating efficiency while preventing damage.
3Reliability
If a switching transistor is introduced to control the heating film power, then the operating power can be regulated to prevent damage, but the device complexity increases
Solution Approach 1:
A switching transistor is introduced as an intermediary component between the heating film and the direct current buses. The switching transistor controls the power delivery to the heating film, preventing excessive power when voltage increases while maintaining full power capability when needed. This intermediary device protects the heating film from damage.
Solution Approach 2:
The controller dynamically changes the operating parameters (duty cycle) of the switching transistor based on voltage conditions. When voltage exceeds a threshold, the duty cycle is reduced to limit power; when voltage is within normal range, the duty cycle is increased to maximize heating efficiency. This parameter adjustment resolves the contradiction between power utilization and safety.
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 prevents overheating and damage to the heating film, enhances safety, and maintains efficient battery heating across varying voltage conditions, while accommodating different specifications and reducing the risk of transistor failure.
Implementation Method 1
An operating principle of the heating film is to convert electric energy into thermal energy based on electrothermal effect, to heat an electrochemical cell
Data Source
AI summary
A energy storage system includes battery pack and a controller. The battery pack includes an electrochemical cell, a heating film, a first switching transistor, and a first drive circuit. The heating film and the first switching transistor are connected in series, and then connected in parallel between a positive direct current bus and a negative direct current bus. The first drive circuit is configured to output a pulse signal, to drive the first switching transistor to be turned on and turned off. The controller is configured to: if a voltage between the positive direct current bus and the negative direct current bus is greater than a voltage threshold, reduce a duty cycle of the pulse signal; or if a voltage between the positive direct current bus and the negative direct current bus is less than or equal to a voltage threshold, increase a duty cycle of the pulse signal.