Shunt Voltage Pulse Conversion for Switching Circuit Thermal Protection
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Solution Overview
Problem
Existing battery management systems (BMS) in electric vehicles struggle to effectively protect switching devices from damage due to excessive current or thermal stress, leading to potential failure and damage to other components.
Innovation Solution
A BMS system that converts sensed voltage across a shunt resistor to a series of electrical pulses indicative of thermal energy or power dissipation, using conversion circuitry to generate control signals for switching devices, allowing for timely intervention to prevent damage by controlling the switching devices based on cumulative thermal energy or junction temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switches are used to control power delivery, then the system can protect against overcurrent, but the response time is slow and mechanical wear reduces reliability
Solution Approach 1:
The patent replaces mechanical switches with solid-state switching circuitry that uses electronic signals to control power delivery. The system employs transistors or other semiconductor devices as switching elements, which can respond to control signals in microseconds or nanoseconds, eliminating the mechanical wear and slow response times inherent in mechanical switch systems while maintaining the overcurrent protection function.
2Reliability
If simple current limiting is implemented, then the system structure remains simple, but it cannot effectively protect against cumulative thermal damage
Solution Approach 1:
The patent introduces thermal energy sensing circuitry as an intermediary between the switching device and the control logic. This sensing mechanism measures parameters such as voltage drop across a sense resistor or junction temperature to detect cumulative thermal energy, allowing the system to protect against thermal damage without requiring complex direct temperature measurement equipment.
Solution Approach 2:
The system replaces complex thermal measurement mechanisms with electrical measurements of thermal energy. By measuring voltage, current, or other electrical parameters that correlate with thermal energy accumulation, the system achieves effective thermal protection through simple electrical sensing and calculation rather than complex thermal measurement hardware.
3Measurement precision
If precise thermal energy measurement is implemented, then protection accuracy improves, but measurement and control complexity increases
Solution Approach 1:
The patent uses electrical parameters (voltage, current) as intermediaries to represent thermal energy. By measuring easily obtainable electrical quantities and calculating thermal energy from these measurements, the system achieves precise thermal energy measurement without requiring complex direct thermal sensing hardware.
Solution Approach 2:
The system substitutes complex thermal measurement and calculation mechanisms with simple electrical measurements and digital processing. Thermal energy is determined from voltage and current measurements using established electrical-thermal relationships, eliminating the need for complex thermal sensors and reducing measurement circuit complexity while maintaining precision.
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
The system effectively protects switching devices and other components by preventing damage from excessive current or thermal stress, improving reliability and reducing costs through the use of solid-state switches, while enhancing response time and reducing mechanical switch reliance.
Implementation Method 1
a transconductor to convert the detected voltage to a current based on a transconductance determined by a reference current and a reference voltage
Implementation Method 2
a current to power converter to convert the current to a value representative of power dissipated in the switching circuit
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A device to convert a detected voltage, that is indicative of current conducted by a switching circuit, to a series of electrical pulses that is indicative of electrical power dissipated by the switching circuit responsive to the current. The device includes a transconductor circuit including a first circuit to receive a reference current and a first reference voltage, and to obtain a transconductance based on an auto-generated bias current and the reference current and the first reference voltage, where a value of the transconductance is determined by the reference current and the first reference voltage. The transconductor circuit further includes a second circuit coupled to the first circuit to receive the detected voltage, and to generate a first current based on the detected voltage and the obtained transconductance.