Power Supply Clamping Circuit for Start-Up Overshoot Control
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Solution Overview
Problem
Power supplies face challenges in preventing overshoot of output current during the start-up period due to the inability to quickly increase comparison voltage, leading to potential start-up failures or extended start-up times.
Innovation Solution
A clamping circuit that senses the input voltage during the start-up period, determines a clamping voltage in an inverse relationship with the peak voltage, and clamps the comparison voltage to prevent overshoot by using a switch control circuit, operational amplifier, and source current sources to manage the voltage levels effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the comparison voltage is quickly increased during start-up period, then the start-up time is reduced, but overshoot of output current occurs
Solution Approach 1:
The clamping voltage is determined in advance by sensing the input voltage during the start-up period before the comparison voltage increases. This preliminary determination of clamping voltage based on sensed input voltage prevents overshoot while enabling quick start-up, as the clamping circuit is already prepared to limit the comparison voltage appropriately when it rises
Solution Approach 2:
The switch control circuit senses the input voltage during the start-up period and uses this feedback information to determine the clamping voltage. This feedback mechanism ensures that the clamping voltage is appropriately set based on the actual input voltage conditions, preventing overshoot while maintaining efficient start-up
2Object-affected harmful factors
If the comparison voltage is slowly increased during start-up period, then overshoot is prevented, but start-up time is extended
Solution Approach 1:
The clamping voltage is determined in advance by sensing the input voltage during the start-up period before the comparison voltage increases. This preliminary determination of clamping voltage based on sensed input voltage prevents overshoot while enabling quick start-up, as the clamping circuit is already prepared to limit the comparison voltage appropriately when it rises
Solution Approach 2:
The clamping voltage is dynamically determined based on the sensed input voltage during the start-up period. Rather than using a fixed clamping voltage, the circuit adapts the clamping level to the actual input conditions, allowing optimal performance that prevents overshoot while maintaining fast start-up
3Use of energy by moving object
If the capacity of the capacitor is increased to acquire higher power factor, then the power factor is improved, but the comparison voltage cannot be quickly increased during start-up
Solution Approach 1:
The circuit changes the operating parameters during the start-up period by applying a first source current to quickly charge the capacitor and generate the comparison voltage, rather than relying solely on the capacitor's inherent charging characteristics. This parameter change allows fast voltage rise despite large capacitance, and the clamping circuit ensures overshoot is still prevented
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 overshoot of the output current by quickly increasing and managing the comparison voltage during the start-up period, ensuring stable operation and reducing the risk of start-up failures.
Implementation Method 1
an auxiliary wire coupled electromagnetically with the primary wire, wherein the switch control circuit senses the input voltage using an auxiliary voltage of the auxiliary wire
Data Source
AI summary
A power supply includes a power switch and a switch control circuit controlling a switching operation of the power switch using a comparison voltage generated according to an output, determining a clamping voltage by sensing an input voltage during a start-up period, and clamping the comparison voltage to the clamping voltage during the start-up period.