Electronic Switch ZVS Detection via Capacitor Voltage Discharge

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Solution Overview

Problem

Switching elements in electronic circuits experience high switching and conduction losses due to output capacitance charging and current flow through rectifier elements, necessitating efficient detection of zero voltage switching (ZVS) conditions to minimize these losses.

Innovation Solution

A method involving a capacitor coupled to load path nodes of an electronic switch with a switching element and rectifier element in parallel, where the capacitor is charged and discharged via the load path nodes, and its voltage is compared to a first level to detect ZVS conditions and optimize switching times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the switching element switches on while the output capacitance is charged, then the switching element can be operated at high switching frequencies, but relatively high switching losses occur

Engineering Contradiction:

Improveswitching frequencyVSAvoidswitching losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by discharging the output capacitance of the switching element before it switches on again. This is achieved by controlling the free-wheeling diode to conduct and discharge the capacitance during the off-state, ensuring zero voltage switching conditions are met before the next switching event, thereby eliminating switching losses while maintaining high switching frequencies

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If the rectifier element conducts current before the switching element switches on, then the circuit can maintain continuous current flow, but conduction losses increase

Engineering Contradiction:

Improvecontinuous current flowVSAvoidconduction losses

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent applies dynamics by dynamically switching between the rectifier element and the free-wheeling diode based on operating conditions. The free-wheeling diode is controlled to conduct during specific intervals to discharge the output capacitance and maintain continuous current flow, replacing the rectifier element's conduction role during these periods. This dynamic switching reduces conduction losses by utilizing the lower on-resistance of the free-wheeling diode while maintaining current continuity

Inventive Principle:

Principle #15Dynamics

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

Reduces switching and conduction losses by ensuring zero voltage switching, thereby improving the efficiency of the electronic circuit operation.

Implementation Method 1

charging a capacitor coupled to load path nodes of an electronic switch

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the rectifier element may conduct a current before the switching element switches on. A current flowing through the rectifier element causes conduction losses

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

a further circuit element, such as an inductance, discharges the output capacitance before the switching element again switches on

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20250364974A1Method for operating a switching element connected in parallel with a rectifier element and electronic circuit

Publication Date: 2025.11.27 INFINEON TECH AUSTRIA AG

AI summary

Disclosed is a method for operating a switching element connected in parallel with a rectifier element and an electronic circuit. The method includes charging a capacitor coupled to load path nodes of an electronic switch, wherein the electronic switch includes a switching element and a rectifier element connected in parallel with a load path of the switching element and between the load path nodes; allowing the capacitor to be discharged via the load path nodes of the electronic switch; and comparing a capacitor voltage across the capacitor with a first voltage level.