Capacitive Voltage Divider Circuit for Bridging Voltage Interruptions
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Solution Overview
Problem
Existing switched-mode power supplies face challenges in handling high voltage RMS values, leading to electrical breakdown of electrolytic capacitors and reduced life expectancy, as they cannot effectively manage power factor compensation and voltage tolerance, resulting in inefficiencies and potential damage.
Innovation Solution
A circuit arrangement featuring two series-connected capacitors forming a capacitive voltage divider, with one capacitor acting as a storage capacitor connected to a linear voltage regulator and a discharge diode, and the other capacitor in parallel to prevent recharging, utilizing a MOSFET transistor as a source follower with adjustable charging voltage and avalanche diode for freewheeling, along with Zener or suppressor diodes for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electrolytic capacitors are used in switched-mode power supplies with high supply voltage, then the power supply can operate at higher voltage levels, but the capacitors experience electrical breakdown and reduced life expectancy
Solution Approach 1:
The patent divides the single high-voltage capacitor into two series-connected capacitors with different capacitance values. This segmentation allows each capacitor to handle a portion of the voltage stress, preventing electrical breakdown while maintaining the required power handling capability. The first capacitor (C1) with lower capacitance handles voltage spikes and transient conditions, while the second capacitor (C2) with higher capacitance provides the necessary energy storage, thereby improving reliability without sacrificing power capability.
Solution Approach 2:
The patent changes the parameter distribution by assigning different capacitance values to the two series-connected capacitors rather than using equal values. This parameter optimization ensures that the capacitor with lower capacitance (C1) handles transient voltage conditions, while the capacitor with higher capacitance (C2) provides sufficient energy storage. This parameter change allows the power supply to operate at high voltage levels while extending capacitor life expectancy by preventing over-stress conditions.
2Reliability
If two capacitors of the same capacitance are connected in series to handle high voltage, then the voltage tolerance is improved, but the total capacitance is reduced to 50% and component volume increases by 400%
Solution Approach 1:
The patent applies asymmetry by using two capacitors with different capacitance values instead of identical capacitors. The first capacitor (C1) has a lower capacitance value optimized for handling voltage spikes and transient conditions, while the second capacitor (C2) has a higher capacitance value optimized for energy storage. This asymmetric configuration maintains the required voltage tolerance capability while minimizing the total component volume, as each capacitor is sized for its specific function rather than both being oversized for the more demanding requirement.
Solution Approach 2:
The patent optimizes the capacitance parameters of the two series-connected capacitors to achieve the best balance between voltage tolerance and total capacitance. By carefully selecting different capacitance values for C1 and C2, the circuit maintains sufficient voltage handling capability while preserving adequate total capacitance for energy storage, thereby reducing the overall component volume compared to using two equal-value capacitors.
3Reliability
If a linear regulator is used to charge a capacitor to a defined voltage level, then the capacitor can be fully utilized, but significant power loss is converted into heat
Solution Approach 1:
The patent employs periodic action through the discharge diode that periodically discharges the first capacitor (C1) when its voltage exceeds a certain threshold. This periodic discharge prevents continuous charging and discharging cycles through the linear regulator, thereby reducing the continuous power loss and heat generation. The capacitor is charged only when needed and discharged when it reaches optimal voltage, creating a periodic rather than continuous operation mode that significantly reduces energy loss.
Solution Approach 2:
The patent extracts the voltage regulation function from the linear regulator by using the series connection of capacitors with different capacitance values. The capacitor with lower capacitance (C1) naturally limits the charging current and voltage, reducing the burden on the linear regulator. This extraction of the voltage limiting function to the capacitor network itself reduces the power loss in the linear regulator while maintaining adequate capacitor utilization.
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
This solution effectively bridges voltage interruptions, reduces heat-generated power loss, and allows for efficient energy storage and regulation, extending the lifespan of capacitors and improving overall power supply reliability.
Implementation Method 1
two series-connected capacitors (C1, C2) which form a capacitive voltage divider (30)
Implementation Method 2
one of the capacitors, which works as a storage capacitor (C2), is connected to a linear voltage regulator (10)
Implementation Method 3
a discharge diode or freewheel-diode (20) is connected to the storage capacitor (C2)
Implementation Method 4
An avalanche diode located within the MOSFET transistor operates as a freewheeling diode during a voltage interruption
Implementation Method 5
The voltage regulator is advantageously constructed from a MOSFET transistor as a source follower
Implementation Method 6
A zener diode or a suppressor diode, which limits the voltage between gate and source of the MOSFET transistor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a circuit arrangement for bridging voltage interruptions with two capacitors (C1, C2) connected in series, which form a capacitive voltage divider (30), wherein one of the capacitors (C2), which acts as a storage capacitor, is connected to a linear voltage regulator (10) and a discharge diode (20) and the other capacitor (C1) is connected in parallel to the linear regulator input (E) and the linear regulator output (A) of the voltage regulator (10), so that the other capacitor (C1) prevents the storage capacitor (C2) from being recharged by the linear regulator (10).