Snubber Circuit Inductive Coupling Voltage Clamp

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Solution Overview

Problem

Switched-mode power converters face issues with parasitic resonant circuits being excited during operation, leading to voltage oscillations that exceed the rating of the devices used, necessitating a solution to limit these oscillations.

Innovation Solution

Incorporating a snubber circuit with a second inductor inductively coupled to a first inductor and electrically coupled to a capacitor, which clamps the voltage peaks to a predefined level, thereby limiting the output voltage of the switching circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a power converter operates with switching circuits and parasitic elements, then power conversion functionality is achieved, but voltage oscillations exceed device voltage ratings

Engineering Contradiction:

Improvepower conversion functionalityVSAvoidvoltage oscillations

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a snubber circuit as an intermediary component between the switching circuit and the load. This snubber circuit includes a snubber capacitor and snubber resistor that act as a mediator to absorb and dampen the parasitic oscillations generated during switching operations, thereby protecting the power semiconductor devices from voltage spikes while allowing the power converter to maintain its power conversion functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The snubber circuit is designed to provide beforehand cushioning by pre-positioning energy-absorbing components (snubber capacitor and resistor) that are activated during voltage spike events. The snubber capacitor charges during normal operation and then discharges through the snubber resistor to dampen oscillations before they can damage the power devices, effectively cushioning against harmful voltage excursions in advance.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If parasitic resonant circuits are excited during operation, then power conversion occurs, but voltage amplitudes exceed device ratings

Engineering Contradiction:

Improvepower conversion operationVSAvoiddevice voltage rating compliance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the harmful parasitic oscillations into a beneficial damping effect by utilizing the snubber circuit. The snubber capacitor resonates with the parasitic inductance at the same frequency as the unwanted oscillations, and the snubber resistor dissipates the energy of these oscillations as heat, thereby transforming the harmful resonant behavior into a controlled energy dissipation mechanism that protects the power devices.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If no snubber circuit is used, then device complexity is low, but voltage peaks damage power devices

Engineering Contradiction:

Improvecircuit simplicityVSAvoiddevice voltage withstand capability

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The snubber circuit components serve multiple functions: the snubber capacitor provides both oscillation damping and voltage clamping, while the snubber resistor provides both energy dissipation and damping control. This multi-functionality allows the snubber circuit to protect against voltage spikes and dampen oscillations simultaneously, providing comprehensive protection without requiring multiple separate protection circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 snubber circuit effectively limits voltage peaks across the power converter's components, ensuring safe operation by regulating the output voltage to a predefined level, thus preventing excessive voltage oscillations.

Implementation Method 1

a snubber circuit with a second inductor inductively coupled to a first inductor and electrically coupled to a capacitor

Methodology Applied

Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 2

a capacitor configured to provide or receive a voltage with a predefined voltage level

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9780676B2Power converter with a snubber circuit

Publication Date: 2017.10.03 INFINEON TECH AUSTRIA AG

AI summary

A power converter circuit includes a switching circuit with at least one electronic switch, a capacitor configured to provide or receive a voltage with a predefined voltage level, at least one first inductor, and a snubber circuit. The snubber circuit includes at least one second inductor inductively coupled to the at least one first inductor and electrically coupled to the capacitor.