Transistor Inrush Current Control Without Resistor Overheating
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Solution Overview
Problem
Existing systems for controlling inrush current in power sources are prone to overheating and damage, especially when dealing with sensitive electronics, and require frequent replacement of resistors.
Innovation Solution
A system incorporating a diode between the transistor's emitter and collector, biased to prevent current flow, coupled with a controller to manage the transistor's gate voltage based on output capacitor status, and using a transistor such as IGBT or MOSFET to control inrush current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is used to limit inrush current, then inrush current is reduced, but the resistor is subject to overheating and damage requiring frequent replacement
Solution Approach 1:
The patent extracts the current-limiting function from the resistor and transfers it to the transistor. The transistor is configured to limit inrush current during power-on, while the diode is biased to prevent the transistor from conducting during normal operation, thereby removing the thermal burden from the current-limiting component.
Solution Approach 2:
The diode serves as an intermediary component that controls the transistor's operation state. By biasing the diode to block current flow during normal operation, it prevents the transistor from conducting and eliminates continuous power dissipation, while still allowing the transistor to function as the inrush current limiter during power-on transient.
2Manufacturing precision
If a transistor is used to control inrush current, then current control precision is improved, but device complexity increases
Solution Approach 1:
The diode acts as a simple intermediary that controls the transistor's on/off state without requiring complex control circuitry. The diode's biasing configuration automatically prevents the transistor from conducting during normal operation, providing precise current control during power-on while maintaining simple circuit topology.
Solution Approach 2:
The transistor and diode combination provides self-regulating current control. The transistor automatically limits inrush current during power-on, and the diode's biasing automatically prevents continuous conduction, eliminating the need for external control signals or complex timing circuits.
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 inrush current by ensuring the transistor operates in an optimal state, reducing the likelihood of damage and extending the lifespan of components.
Implementation Method 1
a diode coupled between the emitter of the transistor and the collector of the transistor, the diode biased to reduce a likelihood of current flowing through the diode from the collector to the emitter
Implementation Method 2
apply an on mode voltage to the gate of the transistor to cause the transistor to operate in an on mode to allow a driving current to pass through the transistor to power the load
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A system for controlling inrush current between a power source (102) and a load (104) includes an output capacitor (106) configured to be coupled in parallel with the load. The system also includes a transistor (110) having a gate (116), a collector (112) configured to be coupled to the power source, and an emitter configured to be coupled to the load. The system also includes a collector resistor (118) coupled between the collector of the transistor and the gate of the transistor. The system also includes an emitter capacitor (120) coupled between the gate of the transistor and the emitter of the transistor to facilitate current flow from the power source through the collector resistor and the emitter capacitor to charge the output capacitor.