Startup Circuit Dynamic Current Control for Switching Power Supply
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Solution Overview
Problem
Existing switching power supply devices face challenges in preventing heat generation and combustion during startup, particularly when anomalies occur, as they rely on constant startup currents that can lead to excessive heat or combustion, especially when the power supply terminal is shorted to ground.
Innovation Solution
A semiconductor device and startup circuit that dynamically control the startup current based on the voltage value of the power supply terminal, ensuring almost no current flows when the terminal is shorted to ground and increasing the current only as the power supply voltage rises, thereby preventing heat generation and combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant startup current is supplied to charge the capacitor during startup, then the capacitor can be charged reliably, but excessive heat generation and combustion may occur when the power supply terminal is shorted to ground
Solution Approach 1:
The startup circuit dynamically adjusts the startup current based on the voltage at the power supply terminal. When the terminal is shorted to ground (voltage near 0V), the startup current is nearly zero. As the power supply voltage rises during normal startup, the startup current increases proportionally to charge the capacitor. This dynamic current adjustment prevents heat generation during short-circuit conditions while ensuring reliable capacitor charging during normal operation.
Solution Approach 2:
The invention changes the parameter of startup current from a constant value to a variable value that depends on the power supply terminal voltage. The startup current is controlled to be proportional to the power supply voltage, transforming the fixed current characteristic into a voltage-dependent current characteristic that adapts to different operating conditions.
2Object-affected harmful factors
If the startup current is limited to prevent heat generation, then safety is improved, but the startup time may be extended
Solution Approach 1:
The startup circuit uses dynamic current control where the startup current increases as the power supply voltage rises. During early startup when voltage is low, current is limited for safety. As voltage increases and the capacitor charges, the current naturally increases to maintain efficient charging, thus minimizing startup time while preventing excessive heat generation.
Solution Approach 2:
The startup circuit uses the power supply terminal voltage as feedback to control the startup current. The voltage signal is fed back to the current control circuit, which adjusts the current proportionally. This feedback mechanism ensures that current is limited when voltage is low (preventing heat) but increases when voltage rises (reducing startup time).
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 solution effectively prevents heat generation and combustion by adjusting the startup current in response to the power supply voltage, ensuring reliable operation and reducing the time required for startup while minimizing current flow during anomalies.
Implementation Method 1
a startup circuit, connected between the high-voltage input terminal and the power supply terminal, which charges the capacitor while controlling the startup current at a magnitude corresponding to the voltage value of the power supply terminal
Implementation Method 2
a capacitor for voltage stabilization connected to an auxiliary winding of the transformer
Implementation Method 3
induce a voltage in the secondary side of a transformer by turning a switching element connected to the primary-side winding on and off
Data Source
AI summary
A semiconductor device for switching power supply control limits the startup current supplied from a high-voltage input terminal, and prevents heat generation and combustion in case of an anomaly. A high-voltage input terminal is connected to the main winding of a transformer, and is supplied with a startup voltage upon input of a power supply to the switching power supply device. A power supply terminal is connected to a capacitor, and outputs a startup current to charge the capacitor after input of the power supply input. A startup circuit is connected between the high-voltage input terminal and the power supply terminal, and charges the capacitor while increasing the startup current with magnitude proportional to the voltage value of the power supply terminal, and after startup, turns off the startup current and supplies the power supply voltage only from the auxiliary winding of the transformer.