Voltage Regulator Control for Short-Circuit Protection
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Solution Overview
Problem
Voltage regulators face damage due to short-circuit conditions, as existing control methods fail to prevent inductor current from reaching harmful levels in a timely manner, leading to increased costs and component stress.
Innovation Solution
The control device monitors the ON interval duration and lengthens the subsequent OFF interval to ensure adequate discharge of the inductor current, preventing it from exceeding saturation values, and discriminates between temporary and permanent short-circuit conditions to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control methods are used to regulate output voltage, then the voltage regulator can maintain stable output under normal conditions, but the inductor current may reach harmful levels during short-circuit conditions, causing component damage
Solution Approach 1:
The control device performs preliminary detection of the ON interval duration to identify short-circuit conditions before they cause harmful inductor current levels. By detecting when the ON interval equals a predetermined maximum value, the system takes preventive action by lengthening the OFF interval before the inductor current can reach damaging saturation levels.
Solution Approach 2:
The control device continuously monitors the ON interval duration and uses this feedback information to dynamically adjust the OFF interval length. When the feedback indicates a short-circuit condition (ON interval equals maximum), the system responds by extending the OFF interval to ensure adequate discharge time, thereby preventing harmful current levels.
2Reliability
If the OFF interval is extended to prevent inductor current saturation, then component safety is improved, but the switching frequency decreases and regulation response time increases
Solution Approach 1:
The control device dynamically adjusts the OFF interval length based on real-time detection of short-circuit conditions. During normal operation, the OFF interval maintains standard duration to preserve switching frequency and response time. When a short-circuit is detected (ON interval equals maximum), the OFF interval is temporarily extended only for that cycle to discharge the inductor, then returns to normal duration, thus minimizing the impact on overall switching frequency while providing protection when needed.
3Measurement precision
If the control device continuously monitors inductor current to detect short-circuits, then detection precision is improved, but device complexity increases
Solution Approach 1:
The control device uses the ON interval duration as an intermediary parameter to indirectly detect short-circuit conditions. Instead of directly monitoring inductor current with complex sensing circuits, the system measures the time duration of the ON interval, which serves as a proxy indicator. When the ON interval equals the predetermined maximum value, this intermediary measurement reliably indicates a short-circuit condition, achieving accurate detection with simpler circuitry.
Data Source
AI summary
A method includes generating a control signal for controlling a switch element, and determining at each switching cycle alternation of an ON interval with storage of energy in the inductor element starting from an input voltage, and an OFF interval with transfer of the energy stored in an inductor element into a storage element on which an output voltage is present. The method includes when the inductor current reaches the first threshold value before the end of a first interval, determining the end of the ON interval at the end of the first interval. The method includes following detection of the ON interval having a duration equal to the first interval, the detection being indicative of a possible short-circuit condition at output, determining the OFF interval having a second duration equal to a lengthened interval longer than the first duration.