Capacitor Voltage Balancing Circuit Using Switchable Semiconductors
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Solution Overview
Problem
Existing circuits for balancing capacitor voltages in DC circuits suffer from significant electrical losses due to continuous cross currents during normal operation, which reduces efficiency and can lead to capacitor damage from uneven voltage distribution.
Innovation Solution
A circuit with switchable semiconductors and balancing elements that only activate when necessary to balance capacitor voltages, using a self-controlling mechanism that eliminates unnecessary power losses by charging the capacitor with the lowest voltage until voltages are symmetric, and employing MOSFETs and Zener diodes for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous cross currents are used to balance capacitor voltages, then capacitor voltage balancing is achieved, but significant electrical losses occur reducing efficiency
Solution Approach 1:
The patent implements periodic action by using pulse frequency to apply balancing only when voltage differences exceed a threshold, rather than continuous cross currents. The switchable semiconductors are activated periodically based on voltage monitoring, eliminating continuous energy losses while maintaining capacitor voltage balancing reliability.
Solution Approach 2:
The circuit employs self-service through automatic voltage detection and control mechanisms that monitor capacitor voltages and activate balancing only when needed. The system self-regulates by comparing voltages across series-connected capacitors and triggering corrective action only when imbalance exceeds predetermined thresholds, eliminating the need for continuous external intervention and reducing energy waste.
2Reliability
If simple resistor-based balancing is used, then capacitor voltages are balanced, but continuous power losses reduce overall converter efficiency
Solution Approach 1:
The patent applies dynamics by replacing static resistor-based balancing with dynamic switchable semiconductor elements that can be activated or deactivated based on real-time voltage conditions. This dynamic approach allows the system to adapt its balancing behavior to actual operational needs, maintaining voltage balance while minimizing continuous power losses and improving overall converter efficiency.
Solution Approach 2:
The circuit implements parameter changes by using switchable semiconductors to dynamically alter circuit parameters (conductivity, resistance) based on voltage imbalance conditions. When balancing is required, the semiconductors change their electrical parameters to enable current flow; when balanced, they return to high-impedance state, thereby changing the circuit's electrical characteristics adaptively to maintain efficiency.
3Power
If multiple capacitors are connected in series to achieve high DC voltage, then the required voltage level is reached, but uneven voltage distribution can cause capacitor damage
Solution Approach 1:
The patent implements feedback mechanisms by continuously monitoring the voltage across each capacitor in the series connection and using this information to control the switchable semiconductor elements. The feedback loop detects voltage imbalances and triggers corrective action by activating specific semiconductors to redistribute charge, thereby maintaining reliable voltage distribution while preserving the high DC voltage capability of the series-connected capacitor bank.
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 significantly reduces electrical losses and prevents capacitor damage by dynamically balancing voltages only when needed, maintaining efficiency and extending capacitor lifespan.
Implementation Method 1
A circuit with switchable semiconductors and balancing elements that only activate when necessary to balance capacitor voltages, using a self-controlling mechanism that eliminates unnecessary power losses by charging the capacitor with the lowest voltage until voltages are symmetric, and employing MOSFETs and Zener diodes for efficient operation.
Implementation Method 2
employing MOSFETs and Zener diodes for efficient operation
Data Source
AI summary
A circuit for balancing capacitor voltages at capacitors in a DC circuit includes a first circuit path having first and second capacitors connected in series between first and second potentials of a DC voltage of the DC circuit, with a first center tap arranged between the first and second capacitors. A second circuit path includes first and second switchable semiconductors and first and second balancing elements which are connected in series between the first and second potentials. The first switchable semiconductor is arranged at the first potential, the second switchable semiconductor at the second potential, and the first and second balancing elements are arranged between the first and second switchable semiconductors, with a second center tap arranged between the balancing elements. A first electrical connection is established between the first center tap in the first circuit path and the second center tap in the second circuit path.