Programmable Power Limiting for Transistor Overheating
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Solution Overview
Problem
Power transistors in electronic devices face overheating and potential damage due to excessive power dissipation during current overloads, which existing current limiting systems fail to adequately address, as they do not protect the transistors themselves from high inrush currents and parasitic inductance-related issues.
Innovation Solution
A programmable power limiting system that includes a switch with current and voltage monitoring, a current regulator, and a power meter to regulate current to a predetermined limit, measure power dissipation, and shut off the switch when a power limit is reached, using a capacitor to integrate voltage and compare it with a reference voltage to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current limitation is implemented to protect electronic devices from current overload, then device protection is improved, but power transistor overheating risk increases due to excessive power dissipation
Solution Approach 1:
The patent introduces a power metering circuit as an intermediary between the current limiting circuit and the switch transistor. This circuit measures the power dissipated by the transistor and provides an additional control signal to shut off the switch when power exceeds a predetermined threshold, thereby protecting the transistor from overheating while maintaining device protection
Solution Approach 2:
The patent implements a feedback mechanism where the power metering circuit continuously monitors the power dissipated by the switch transistor and feeds back control signals to the current regulator and switch control. This closed-loop feedback ensures that both current and power limits are enforced, preventing transistor overheating while maintaining device protection
2Object-affected harmful factors
If current is limited to protect electronic devices, then device safety is improved, but power transistor damage risk increases due to power dissipation during high current conditions
Solution Approach 1:
The patent segments the protection function into two independent but coordinated circuits: a current limiting circuit that protects devices from overcurrent, and a power metering circuit that protects transistors from overheating. Each circuit independently monitors its parameter and provides control signals, ensuring both device safety and transistor protection without interference
Solution Approach 2:
The power metering circuit performs preliminary action by continuously monitoring power dissipation and preparing to shut off the switch before the transistor reaches dangerous temperature levels. The circuit integrates power over time and triggers shutdown when the integral exceeds a threshold, preventing thermal damage before it occurs
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
Effectively limits power dissipation in power transistors, preventing overheating and physical damage by regulating current and power, ensuring the switch disconnects during overloads and allowing for cumulative monitoring of multiple faults, thus protecting the device and transistors.
Implementation Method 1
measuring an amount of power dissipated in the switch while the current is being regulated
Implementation Method 2
excessive power dissipated in them during these high current conditions. This can cause physical damage to the power transistors
Data Source
AI summary
Various systems, methods and apparatuses are provided herein for limiting power dissipation in a switch. As one example, a method for limiting power dissipation is disclosed. The method includes monitoring current through the switch, and based at least in part on detecting that the current is at least as great as a predetermined current limit, regulating the current to the predetermined current limit. The method also includes measuring an amount of power dissipated in the switch while the current is being regulated, and opening the switch when the amount of power has reached a predetermined power limit.