Active Clamp Circuit With Feedback-Stabilized Clamp Voltage
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Solution Overview
Problem
Active clamp circuits face challenges in maintaining a constant clamp voltage during the operation of inductive loads, leading to extended operational periods and vulnerability to electrostatic discharge (ESD) when power supply voltage is not available.
Innovation Solution
An active clamp circuit with a control circuit that amplifies the voltage across a resistance to control the current through a switch element, using a zener diode and additional diodes to regulate voltage and prevent reverse flow, ensuring a constant clamp voltage and protecting against ESD by discharging surges to ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zener diode is used to clamp the induced voltage, then the switch element is protected from overvoltage, but the clamp voltage fluctuates due to current-voltage characteristic changes
Solution Approach 1:
The patent introduces a feedback mechanism where the clamp voltage is detected and fed back to control the switch element. When the clamp voltage exceeds a predetermined threshold, the control circuit adjusts the switch element's conduction state to regulate the voltage, thereby stabilizing the clamp voltage despite fluctuations in zener diode characteristics.
Solution Approach 2:
The patent changes the operating parameters of the zener diode by controlling the conduction state of the switch element in response to clamp voltage variations. This dynamic parameter adjustment compensates for the non-linear current-voltage characteristics of the zener diode, maintaining stable clamp voltage.
2Reliability
If the active clamp circuit operates to absorb energy from inductive load, then the switch element is protected from induced voltage, but the operational period is extended and becomes wasteful time
Solution Approach 1:
The patent enables the active clamp circuit to continuously monitor and regulate the clamp voltage throughout the operation of the inductive load. By maintaining continuous voltage control rather than intermittent clamping, the circuit protects the switch element without requiring extended active clamp operation periods, thus reducing wasted time.
3Loss of energy
If the active clamp circuit is not supplied with power supply voltage, then power consumption is reduced, but the circuit cannot protect against electrostatic discharge (ESD)
Solution Approach 1:
The patent incorporates ESD protection circuitry that is pre-configured and automatically activated when ESD events occur, even without power supply voltage. The protection mechanism is prepared in advance and requires no external power to function, ensuring continuous protection capability while maintaining low power consumption during normal operation.
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 shortens the active clamp operation period, maintains a constant clamp voltage, and enhances resistance to ESD by effectively managing current and voltage fluctuations, thereby improving the efficiency and reliability of the active clamp circuit.
Implementation Method 1
a first diode connected to the first switch element and breaks down by an overvoltage applied to the first switch element
Implementation Method 2
The first resistance is connected to the first diode and detects a current through the first diode
Implementation Method 3
A amplifier circuit amplifies a voltage across the first resistance and outputs a current
Data Source
AI summary
According to one embodiment, an active clamp circuit includes a first switch element, a first diode, a first resistance, a first control circuit and a second control circuit. The first diode is connected to the first switch element and breaks down by an overvoltage applied to the first switch element. The first resistance is connected to the first diode and detects a current through the first diode. The first control circuit is configured to amplify a voltage across the first resistance and controls a current through the first switch element. The second control circuit is configured to control a conduction of the first switch element in accordance with the voltage across the first resistance.