Charge Extraction Circuit for Voltage Converter Overshoot
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Solution Overview
Problem
Conventional power supply circuits struggle to quickly respond to and suppress overshoot caused by a sharp reduction in load current, as they rely solely on control circuits that are inadequate for handling rapid changes in inductor current.
Innovation Solution
A power supply circuit incorporating a voltage conversion circuit and a charge extraction circuit with switching devices and capacitors to actively extract excess charge from the output capacitor when overshoot is detected, using a combination of resistors and capacitors in parallel to manage the charge extraction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a capacitor with large capacitance is employed to suppress output voltage rise, then the output voltage stability is improved, but the device complexity and component size increase
Solution Approach 1:
The patent divides the single large capacitor into multiple smaller capacitors (first output capacitor and second output capacitor) that can be connected in parallel. This segmentation achieves the required total capacitance for voltage stability while reducing the complexity and size of individual components, making the circuit more manageable and easier to implement.
Solution Approach 2:
The patent introduces a switching device that dynamically connects or disconnects the second output capacitor based on the operating conditions. When the switching device is turned on, both capacitors work together to provide high capacitance for voltage stability. When turned off, only the first capacitor is active, reducing the overall capacitance. This dynamic adjustment allows the system to adapt to different load conditions and maintain stability without requiring a permanently large capacitor.
2Loss of energy
If the switching device is kept off to reduce inductor current, then energy loss is reduced, but the response speed to load current changes deteriorates
Solution Approach 1:
The patent employs a dynamic control strategy where the switching device transitions between on and off states based on real-time load conditions. During steady-state operation with stable load current, the switching device remains off to minimize inductor energy loss. When a sudden load current change is detected, the switching device turns on rapidly to provide the necessary current response. This dynamic switching allows the system to optimize between energy efficiency and response speed depending on operational requirements.
Solution Approach 2:
The patent prepares the switching device and associated circuitry in advance to enable rapid response when load changes occur. The second output capacitor is pre-charged and positioned to immediately supply current when the switching device turns on, rather than waiting for the inductor to build up current. This preliminary preparation of the discharge path allows the system to respond quickly to load changes without requiring the inductor to be continuously energized, thus reducing energy loss 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 effectively suppresses overshoot by quickly responding to sudden load current reductions, reducing the time required to stabilize the output voltage and minimizing the need for large capacitors, thus enhancing the power supply's responsiveness and efficiency.
Implementation Method 1
an output capacitor COUT coupled to an output voltage terminal To
Implementation Method 2
a switching device SW1 coupled between an input voltage terminal Ti to which an input voltage VIN is to be applied, and an inductor L1; a switching device SW2 coupled between a junction point of the switching device SW1 and the inductor L1 and a ground terminal GND
Data Source
AI summary
A power supply circuit that includes a voltage conversion circuit (CONV) for outputting an output voltage to an output voltage terminal, the output voltage being stepped up or stepped down from an input voltage (VIN) presented to an input voltage terminal, an output capacitor (COUT) coupled to the output voltage terminal, and a charge extraction circuit for extracting the charge of the output capacitor (COUT). Quick response to overshoot of VOUT generated by a sudden reduction in load current (ILOAD) is afforded, and overshoot is minimized.