Switching Power Supply: Overcurrent Detection Simplified
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Summary
Problems
Conventional switching power supply apparatuses face challenges in preventing output current from depending on input voltage, leading to increased stress on components and higher manufacturing costs, especially when input voltage is high, due to the delay in overcurrent detection and the need for additional circuitry for input voltage measurement.
Innovation solutions
A switching power supply apparatus that measures the gradient of the electric current flowing through the switching device to correct the overcurrent detection point without directly measuring the input voltage, using a current variation measurement circuit and an overcurrent detection-point correction circuit to adjust the reference voltage based on the current gradient, thereby reducing the number of external parts and power loss.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If input voltage measurement circuit is added to correct overcurrent detection point, then overcurrent protection accuracy is improved, but device complexity and power consumption increase
Why choose this principle:
The patent applies self-service by using the existing current measurement circuit to simultaneously perform both current measurement and input voltage measurement functions. The control circuit processes the current measurement signal to extract both current magnitude and its gradient information, eliminating the need for separate input voltage measurement circuits while maintaining correction accuracy.
Principle concept:
If input voltage measurement circuit is added to correct overcurrent detection point, then overcurrent protection accuracy is improved, but device complexity and power consumption increase
Why choose this principle:
The patent makes the current measurement circuit multi-functional by using it to detect both the current magnitude and the input voltage level (through current gradient). This single circuit performs multiple functions: current sensing, voltage sensing, and providing correction signals, thereby reducing overall device complexity while improving overcurrent protection accuracy.
Application Domain
Data Source
AI summary:
A switching power supply apparatus that measures the gradient of the electric current flowing through the switching device to correct the overcurrent detection point without directly measuring the input voltage, using a current variation measurement circuit and an overcurrent detection-point correction circuit to adjust the reference voltage based on the current gradient, thereby reducing the number of external parts and power loss.
Abstract
A switching power supply apparatus has a switching device control circuit for performing overcurrent protection by controlling switching-on/off of a switching device, connected serially to a primary winding of a transformer, so as to make a voltage output from a rectifying and smoothing circuit, connected to a secondary winding of the transformer, have a specific value, and switching off the switching device when the electric current flowing through the switching device exceeds a value as an overcurrent detection point. This control circuit includes: a current variation measurement circuit for measuring a gradient of the electric current flowing through the switching device, based on a current measurement signal output from a circuit for measuring this electric current; and an overcurrent detection-point correction circuit for correcting the overcurrent detection point with respect to the electric current flowing through the switching device, based on a signal output from the current variation measurement circuit.