Active Input Capacitor Balancing Circuit for High Voltage Power Supplies
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Solution Overview
Problem
High voltage power supplies face inefficiencies due to significant leakage current in stacked electrolytic capacitors, leading to unbalanced voltages and premature failure, and traditional balancing methods using resistors increase power consumption and heat dissipation.
Innovation Solution
A high voltage input capacitor balancing circuit that actively balances capacitors without resistors, using a voltage divider and buffer circuit to provide current and reduce power loss, allowing for efficient operation across a wide range of voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional resistor-based balancing methods are used for stacked electrolytic capacitors, then capacitor voltage balance is achieved, but power consumption increases and heat dissipation occurs
Solution Approach 1:
The patent replaces the passive resistor-based balancing mechanism with an active electronic control system. The controller monitors capacitor voltages and uses switching devices to actively transfer charge between capacitors, substituting the mechanical/physical resistor dissipation approach with an electronically controlled charge redistribution mechanism that significantly reduces power loss.
Solution Approach 2:
The patent implements a feedback control system where the controller continuously monitors the voltage across each capacitor in the stacked configuration. Based on this feedback information, the controller adjusts the switching states to maintain voltage balance, enabling dynamic compensation for leakage current variations and achieving reliable balancing without the continuous power dissipation required by resistor-based methods.
2Reliability
If resistor-based balancing is used, then capacitor leakage is compensated, but heat dissipation increases
Solution Approach 1:
The patent replaces the thermal dissipation mechanism of resistors with an electronically controlled charge transfer system. Instead of allowing leakage current to be continuously dissipated as heat through resistors, the system uses switching devices to actively pump charge between capacitors, compensating for leakage without generating significant heat.
3Strength
If high voltage stacked capacitor configuration is used, then voltage rating is achieved, but leakage current increases
Solution Approach 1:
The controller uses feedback from voltage sensors to detect imbalances caused by leakage current in the high-voltage stacked capacitor configuration. Based on this feedback, it actively redistributes charge to compensate for leakage effects, maintaining voltage balance across all capacitors and reducing the net energy loss despite the inherent leakage in high-voltage capacitor stacks.
Data Source
AI summary
In one embodiment, an input capacitor balancing circuit for a power supply is provided. The circuit includes an input capacitance operable to filter input power for the power supply. The input capacitance has a first capacitor and a second capacitor coupled in series between an input voltage and a first node. A voltage divider circuit is coupled to the input voltage and operable to generate a divided voltage therefrom. A buffer circuit is operable to receive the divided voltage and, if the first capacitor and the second capacitor are not balanced, to provide current to the input capacitance to balance the first capacitor and the second capacitor.