Surge Current Suppression Circuit Using Dynamic Switch Control
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Solution Overview
Problem
Conventional surge current suppression circuits fail to effectively control surge currents during the hold-up time, leading to system instability, damage to components, and interference with power grids when power returns after a failure.
Innovation Solution
A surge current suppression circuit comprising a switch, a bypass resistor, a detection resistor, and a comparator that adjusts the capacitor current by turning the switch on or off based on detection voltage thresholds, allowing the current to flow through different resistance paths to manage surge currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is connected in series with the current loop at the input end to limit surge current, then the surge current at the moment of activating is suppressed, but the current magnitude when returning after hold-up time cannot be controlled, causing power grid instability and component damage
Solution Approach 1:
The patent employs a dynamic control approach where the switch transitions between on and off states based on real-time detection of capacitor voltage or current conditions. During power failure, the switch remains on to allow the resistor to limit surge current. When power returns and the capacitor voltage drops below a threshold (or current exceeds threshold), the switch turns off to bypass the resistor, thereby dynamically adapting the circuit configuration to different operational phases and eliminating uncontrolled surge currents during power return.
Solution Approach 2:
The patent implements a feedback mechanism using a detection circuit that continuously monitors the capacitor voltage (or current) and compares it against predetermined thresholds. The detection circuit generates detection signals that feed back to the switch control circuit, which then adjusts the switch state accordingly. This closed-loop feedback system ensures that the surge current suppression mechanism activates only when necessary (during power failure or immediate power return) and deactivates when the system stabilizes, preventing both excessive surge current and unnecessary power loss.
2Loss of energy
If a switch is connected at both ends of the resistor in parallel to reduce loss after surge current, then power loss is reduced, but the system cannot maintain stable operation during the unstable interval when input power is instantaneously powered down and back
Solution Approach 1:
The patent employs a dynamic control approach where the switch transitions between on and off states based on real-time detection of capacitor voltage or current conditions. During power failure, the switch remains on to allow the resistor to limit surge current. When power returns and the capacitor voltage drops below a threshold (or current exceeds threshold), the switch turns off to bypass the resistor, thereby dynamically adapting the circuit configuration to different operational phases and eliminating uncontrolled surge currents during power return.
Solution Approach 2:
The patent prepares the circuit in advance for power failure scenarios by keeping the switch in a default state (on or off depending on design) that ensures surge current limitation is ready to activate. The detection circuit continuously monitors system conditions and is pre-configured with threshold values that trigger the switch state change before dangerous surge currents can develop during power return, thus preliminarily preventing system instability.
3Duration of action of stationary object
If the capacitor voltage is used as low as possible during power failure to extend hold-up time, then the hold-up time requirement is met, but the voltage difference between input grid and capacitor voltage causes high surge current when power returns
Solution Approach 1:
The patent converts the potentially harmful effect of large voltage difference (which causes surge current) into a beneficial control mechanism. The detection circuit monitors the capacitor voltage and detects when it drops to a low level during power failure. This low voltage condition, which would normally cause dangerous surge current upon power return, is instead used as the trigger condition to activate the surge current suppression mechanism (by keeping the switch on or turning it on at the right moment), thereby transforming the harmful voltage difference into a useful control signal.
Solution Approach 2:
The patent applies preliminary anti-action by detecting the low capacitor voltage condition during power failure and preparing the switch to be in the appropriate state before power returns. The detection circuit continuously monitors the voltage and triggers the switch control circuit to ensure the resistor is in the circuit (switch on) when power returns, thereby preemptively preventing the surge current from occurring in the first place rather than reacting after the surge has already damaged the system.
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
Effectively suppresses and controls surge currents upon power return, reducing system instability and component damage, and maintaining stable power delivery.
Implementation Method 1
an energy storage capacitor C1 coupled between the input power source Vdc and the load RL... the energy storage on the capacitor C1 is drawn by the load RL
Implementation Method 2
The detection resistor is coupled to the switch in series, and generates a detection voltage according to a capacitor current flowing through the energy storage capacitor
Data Source
AI summary
A surge current suppression circuit includes a switch, a bypass resistor, a detection resistor, and a comparator. The switch is coupled to a first end of an energy storage capacitor in series, wherein a second end of the energy storage capacitor is coupled to a load and receives an input power source. The bypass resistor is coupled to the switch in parallel. The detection resistor is coupled to the switch in series to generate a detection voltage according to a capacitor current flowing through the energy storage capacitor. The comparator compares the detection voltage with a reference voltage to generate a control signal. When the detection voltage is greater than the reference voltage, the control signal controls the switch to be turned off. When the detection voltage is less than the reference voltage, the control signal controls the main switch to be turned on.