Voltage Doubler Flying Capacitor Short-Circuit Detection

Solution Overview

Problem

Conventional circuits lack a protection mechanism to detect and prevent short circuits in flying capacitors, leading to potential damage from inrush currents and inability to effectively charge stabilizing capacitors to rated voltage.

Innovation Solution

A voltage doubler switched capacitor circuit with a first switch of large conduction impedance for soft start, connecting the flying capacitor in parallel during charging, using a timer to monitor charging time, and issuing a warning for short circuits, which prevents excessive currents and alerts for short-circuit conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If switches with small area are used to reduce inrush current, then inrush current damage is reduced, but charging time increases and charging speed decreases

Engineering Contradiction:

Improveinrush current damageVSAvoidcharging speed

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The circuit performs preliminary charging through the first switch CKC with large conduction impedance before enabling the second and third switches. This preliminary action limits inrush current while gradually charging the stabilizing capacitor, then transitions to faster charging phase once voltage reaches threshold, resolving the contradiction between preventing inrush current and maintaining charging speed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The circuit dynamically switches between two charging paths: initially using the first switch CKC with large impedance for soft-start protection, then transitioning to use second and third switches with smaller impedance for faster charging. This dynamic adjustment of switching states allows the system to adapt charging impedance based on real-time voltage conditions, simultaneously achieving inrush current limitation and efficient charging

Inventive Principle:

Principle #15Dynamics

2Reliability

If conventional overcurrent protection is used, then continuous short circuit to ground is prevented, but flying capacitor short circuit cannot be detected

Engineering Contradiction:

Improvecontinuous short circuit protectionVSAvoidflying capacitor short circuit detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The detection circuit acts as an intermediary monitoring system that observes the charging process through voltage thresholds and timing. It detects abnormal conditions (such as flying capacitor short circuit) by monitoring whether the stabilizing capacitor voltage reaches expected thresholds within expected timeframes, enabling detection of flying capacitor faults without interfering with the main power circuit

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The circuit implements feedback through the detection circuit that monitors charging progress and provides feedback signals. When the stabilizing capacitor voltage fails to reach threshold levels within the expected charging time, the detection circuit generates feedback indicating a potential short circuit condition, allowing the system to respond appropriately to flying capacitor failures

Inventive Principle:

Principle #23Feedback

3Loss of time

If charging current is increased to charge stabilizing capacitor faster, then charging time is reduced, but inrush current increases and may damage load circuit

Engineering Contradiction:

Improvecharging timeVSAvoidinrush current

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The circuit performs preliminary charging through the first switch CKC with large conduction impedance before enabling the second and third switches. This preliminary action limits inrush current while gradually charging the stabilizing capacitor, then transitions to faster charging phase once voltage reaches threshold, resolving the contradiction between preventing inrush current and maintaining charging speed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The circuit dynamically switches between two charging paths: initially using the first switch CKC with large impedance for soft-start protection, then transitioning to use second and third switches with smaller impedance for faster charging. This dynamic adjustment of switching states allows the system to adapt charging impedance based on real-time voltage conditions, simultaneously achieving inrush current limitation and efficient charging

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11870344B2Voltage doubler switched capacitor circuit capable of detecting short circuit of flying capacitor and detection method thereof

Publication Date: 2024.01.09 EGALAX EMPIA TECH INC

AI summary

The invention provides a voltage doubler switched capacitor circuit capable of detecting short circuit of flying capacitor and a detection method thereof. The voltage doubler switched capacitor circuit provides a way to connect the flying capacitor in parallel to the charging path, and calculate whether it is charged to a predetermined voltage in the designed charging time interval, and then it can effectively detect whether the flying capacitor is short-circuited.