Active Capacitor Voltage Balancing With Low-Loss Regulation
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Solution Overview
Problem
The use of multiple electrolytic capacitors in series can lead to uneven voltage distribution due to varying leakage currents, resulting in excessive breakdown voltages and significant energy loss when balancing resistors are employed to equalize these voltages.
Innovation Solution
A voltage regulating device with high-side and low-side controllers and transistors, along with current limiting resistors, is used to dynamically adjust the electrode-to-electrode voltages of capacitors, ensuring balanced voltage distribution and minimizing energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If balancing resistors are used to equalize voltages of series-connected electrolytic capacitors, then voltage distribution is improved, but energy loss increases significantly
Solution Approach 1:
The patent replaces the passive resistor-based voltage balancing mechanism with an active semiconductor switching mechanism. Transistors (Q1-Q4) controlled by comparators (A1, A2) dynamically switch to transfer charge between capacitors, substituting the energy-dissipating resistor system with an energy-conserving active control system that achieves voltage equalization without significant power loss.
Solution Approach 2:
The patent implements feedback control through comparators A1 and A2 that continuously monitor voltage differences across the series-connected capacitors. When voltage imbalance is detected, the feedback signal triggers the appropriate transistor switches to transfer charge from the higher-voltage capacitor to the lower-voltage capacitor, automatically maintaining voltage equilibrium without continuous energy dissipation.
2Stability of the object's composition
If balancing resistors are used to equalize voltages, then voltage distribution is improved, but installation area increases
Solution Approach 1:
The patent merges multiple functions into the semiconductor integrated circuit: voltage monitoring, comparison, control signal generation, and charge transfer switching are all integrated into a single IC device. This consolidation eliminates the need for separate balancing resistors and their associated mounting space, achieving voltage equalization while reducing installation area.
Solution Approach 2:
The semiconductor integrated circuit performs multiple functions: it monitors voltage across capacitor pairs, compares voltages to detect imbalances, generates control signals, and switches charge transfer paths. This multi-functional device replaces the dedicated balancing resistor network, achieving the same voltage equalization goal with significantly reduced component count and installation footprint.
Data Source
AI summary
A voltage regulating device connected to a series circuit of electrolytic capacitors provided between a ground wiring and an input voltage wiring, includes: a high-side terminal connected to the input voltage wiring; a low-side terminal connected to the ground wiring; a middle terminal connected to a connection node between the electrolytic capacitors; and a voltage limiting circuit configured to limit a voltage between the high-side terminal and the middle terminal to a high-side limit voltage or lower by controlling a high-side regulating current between the high-side terminal and the middle terminal according to the voltage between the high-side terminal and the middle terminal, and configured to limit a voltage between the middle terminal and the low-side terminal to a low-side limit voltage or lower by controlling a low-side regulating current between the middle terminal and the low-side terminal according to the voltage between the middle terminal and the low-side terminal.