Battery Management System PWM Frequency Control for Switch Overheating
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Solution Overview
Problem
Existing battery management systems face overheating issues due to voltage and current noise components during on/off switching of switches like FETs, leading to malfunctions, especially when performing battery cell balancing.
Innovation Solution
A battery management system that uses temperature sensors to monitor battery cell temperatures and adjusts PWM signal frequencies and duty ratios based on pre-set tables to prevent overheating, allowing switches to perform balancing functions without thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the controller outputs a PWM signal with a different duty cycle and fixed output frequency for each battery cell to perform cell balancing, then the battery cell balancing function is achieved, but voltage and current noise components occur during switch on/off switching causing overheating of the switch and other circuit components
Solution Approach 1:
The patent applies dynamics by making the PWM output frequency variable rather than fixed. The controller dynamically adjusts the output frequency based on real-time temperature feedback from temperature sensors monitoring the switch and circuit components. When temperature exceeds a threshold, the frequency is reduced to lower switching losses and prevent overheating, while maintaining the cell balancing function through adjusted duty cycles.
Solution Approach 2:
The patent implements feedback by introducing temperature sensors that continuously monitor the temperature of switches and circuit components. The temperature information is fed back to the controller, which uses this feedback to adjust the PWM output frequency and duty cycle in real-time, creating a closed-loop control system that prevents overheating while maintaining balancing performance.
2Reliability
If the PWM signal frequency is reduced to prevent switch overheating, then thermal damage is avoided, but the battery cell balancing efficiency decreases
Solution Approach 1:
The system dynamically adjusts PWM frequency based on temperature conditions rather than using a fixed low frequency. When temperatures are within safe ranges, the frequency is maintained at higher levels for fast balancing. When temperature thresholds are approached, the frequency is dynamically reduced to prevent thermal damage, optimizing both reliability and productivity across different operating conditions.
Solution Approach 2:
The patent changes the PWM signal parameters (frequency and duty cycle) based on temperature conditions. By varying these parameters dynamically rather than maintaining fixed values, the system achieves high balancing efficiency when cool and prevents overheating when temperatures rise, resolving the contradiction between speed and thermal safety.
Data Source
AI summary
The PWM signal corresponding to the at least one switch is output by reducing the output frequency of the PWM signal to be lower than that of the pervious PWM signal output immediately before the output of the PWM signal so as to prevent overheating during the on/off operation of the at least one switch corresponding to the at least one battery cell so that the at least one switch may perform the cell balancing function without being overheated and thus a voltage and current of a noise component during on/off switching of the at least one switch (e.g., an FET) may be reduced to prevent overheating of the at least one switch (e.g., an FET) and other circuit components (e.g., a capacitor, etc.) near the switch due to the voltage and current of the noise component, thereby preventing a malfunction of the battery management system.