Current Sampling Circuit for Parallel Semiconductor Switches
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Solution Overview
Problem
In battery management systems, semiconductor switch devices like MOS transistors used as switch protection devices face challenges with slow response time, high power consumption, and high failure rates due to lack of current equalization among parallel devices, leading to inaccurate current detection and increased costs from thermal management requirements.
Innovation Solution
A current sampling method and circuit that determine the current equalization state of semiconductor switch devices by monitoring temperature differences and adjusting gate voltages to ensure accurate current collection, using temperature sensors and a processing module to calculate the total current flowing through parallel devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple MOS transistors are connected in parallel to increase overcurrent capability, then the current handling capacity is improved, but current equalization among the parallel devices cannot be controlled, leading to reduced measurement precision
Solution Approach 1:
The patent divides the current detection function into individual segments for each MOS transistor by placing separate temperature sensors on each device. This segmentation allows independent monitoring of each transistor's thermal state, enabling precise detection of current distribution across parallel devices and identifying which specific device carries excessive current.
Solution Approach 2:
The patent implements a feedback mechanism where temperature sensor readings from each MOS transistor are continuously monitored and fed back to the control system. When temperature differences indicate uneven current distribution, the system adjusts gate voltages to redistribute current, ensuring current equalization is maintained and measurement precision is preserved.
2Power
If traditional precharging circuits with equalization resistors are used, then the instantaneous current is reduced, but the circuit occupies large area and generates significant thermal power consumption
Solution Approach 1:
The patent replaces the mechanical/electrical precharging circuit with equalization resistors with a thermal-field-based control system. Instead of using resistive elements that occupy PCB space and generate heat, the system uses temperature sensors and gate voltage control to manage current distribution, eliminating the need for physical precharging components.
Solution Approach 2:
The patent changes the control parameter from voltage-based precharging to temperature-based current equalization. By monitoring temperature differences among parallel MOS transistors and adjusting gate voltages accordingly, the system achieves current control without requiring additional passive components or precharging circuitry.
3Power
If traditional precharging circuits with equalization resistors are used, then the instantaneous current is reduced, but thermal power consumption increases requiring special heat dissipation treatment
Solution Approach 1:
The patent replaces the resistive precharging circuit that dissipates thermal energy with an active control system using temperature sensors and gate voltage adjustment. This substitution eliminates continuous thermal power consumption by equalization resistors while still achieving the goal of reducing instantaneous current stress on the main relay.
Solution Approach 2:
The system uses the natural thermal characteristics of the MOS transistors themselves as the sensing mechanism. By measuring temperature differences that naturally arise from uneven current distribution, the system self-diagnoses and self-corrects current imbalance without requiring external cooling components or additional energy dissipation pathways.
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 method allows for accurate current collection in the current equalization state, reducing the risk of device failure and thermal management costs by ensuring equal current distribution among parallel semiconductor switch devices.
Implementation Method 1
obtaining a detected temperature of each semiconductor switch device of a plurality of parallel semiconductor switch devices
Implementation Method 2
determining that the plurality of parallel semiconductor switch devices are in a current equalization state based on the detected temperature
Data Source
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AI summary
The present disclosure discloses a current sampling method and a current sampling circuit. The method comprises: obtaining a detected temperature of each semiconductor switch device of a plurality of parallel semiconductor switch devices; determining that the plurality of parallel semiconductor switch devices are in a current equalization state based on the detected temperature of each semiconductor switch device; obtaining an equalized current flowing through a target semiconductor switch device in the current equalization state, the target semiconductor switch device being any one of the plurality of parallel semiconductor switch devices; determining a total current of a main circuit connected to the plurality of parallel semiconductor switch devices according to the equalized current. The current sampling method and the current sampling circuit provided in the embodiments of the present disclosure improve current sampling accuracy.