Holdup Capacitor Charging Circuit for Surge Current Suppression
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Solution Overview
Problem
Existing power supply systems face issues with surge currents due to overshoot of voltage or current, leading to increased costs and reduced performance and reliability, particularly when dealing with dynamic loads in communication devices.
Innovation Solution
A power supply system with a current suppression circuit that includes transistors and capacitors, where control signals manage the transistors to suppress surge currents by enabling/disabling them based on voltage and current thresholds, using smaller SOA FETs to reduce costs and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a holdup capacitor with larger capacitance value is introduced to suppress oscillation and supply power when power source is temporarily off, then the power supply stability is improved, but surge current is caused in the power supply system
Solution Approach 1:
The control logic activates the first transistor Q1 in advance during normal operation to linearly charge the holdup capacitor C_holdup, preparing it to suppress oscillation and provide backup power. This preliminary charging action ensures the capacitor is ready to mitigate surge current effects when power interruptions occur, resolving the contradiction between improving power supply stability and preventing surge current damage.
2Object-generated harmful factors
If a power supply assisting sub-system with transistors and resistors is used to suppress surge current, then surge current suppression is improved, but device complexity increases
Solution Approach 1:
The first transistor Q1 serves multiple functions: it acts as a current limiter during power-on to suppress surge current, and simultaneously functions as a linear charger for the holdup capacitor during normal operation. This multi-functionality reduces the need for separate dedicated components, thereby suppressing surge current while minimizing the increase in device complexity.
3Ease of manufacture
If smaller SOA FETs are used in the power supply system, then cost is reduced and reliability is improved, but surge current suppression capability is worsened
Solution Approach 1:
The invention changes the operating parameters and mode of the FETs, specifically using the first transistor Q1 in linear mode with a controlled gate-source voltage to limit current. This parameter control approach enables smaller, lower-cost SOA FETs to effectively suppress surge current, resolving the contradiction between reducing manufacturing cost and maintaining surge current suppression capability.
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 suppresses surge currents during both powering on and normal operation, allowing the use of smaller FETs to reduce costs and improve performance and reliability.
Implementation Method 1
a first transistor Q1... configured to linearly charge a holdup capacitor C_holdup... and limiting a current flowing to the holdup capacitor C_holdup
Implementation Method 2
a second transistor Q2... configured to supply power to the load circuit
Data Source
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AI summary
The present disclosure provides a power supply system, including: a power source connected between a first node and a second node for applying an input voltage; a first circuit, connected between the first node and a second circuit; and configured to suppress oscillation caused by load variation of a load circuit that is connected between the first node and the second circuit, and to supply power to the load circuit when the power source is temporarily off; the second circuit, having a first port connected to the first circuit, a second port connected to the load circuit, and a third port connected to the second node; and configured to charge the first circuit and supply power to the load circuit; and a third circuit, connected between the first circuit and the load circuit; and configured to suppress a current flowing into the second circuit. The present disclosure also provides a method of operating such a power supply system.