Stabilivolt Diode RCD Clamp Circuit for Voltage Spike Management

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing clamp circuits for semiconductor switching transistors are large in size and have an unstable clamping effect due to the limitations of capacitance clamp circuits and resistor capacitor diode (RCD) clamp circuits, which result in high costs and poor voltage clamping performance.

Innovation Solution

The proposed solution involves a clamp circuit design that includes an RCD circuit with a stabilivolt diode and additional resistors, which divides the spike voltage across the switching transistor, reducing the voltage withstand requirements of components and minimizing the size and cost of the clamp circuit by increasing the operating threshold and reducing resonance energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a capacitor clamp circuit is used, then the clamp circuit can absorb voltage spikes, but the capacitor volume is relatively large and the device size increases

Engineering Contradiction:

Improvevoltage spike absorptionVSAvoidcapacitor volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The clamp circuit is divided into two functional parts: an RCD circuit for absorbing voltage spikes and a stabilivolt diode for clamping the voltage. This segmentation allows each component to be optimized for its specific function, reducing the overall size compared to a single large capacitor.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the operating parameters by using a stabilivolt diode with a specific reverse breakdown voltage that is lower than the switching transistor's withstand voltage. This parameter change enables effective clamping at lower voltages, allowing the use of smaller RCD circuit components.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a capacitor clamp circuit is used, then voltage clamping is provided, but the switching transistor generates heat due to charge discharge through its channel

Engineering Contradiction:

Improvevoltage clampingVSAvoidswitching transistor heat

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The stabilivolt diode acts as an intermediary element that provides a dedicated path for charge discharge. When the switching transistor turns on, charge flows through the stabilivolt diode instead of through the transistor channel, eliminating the heat generation problem while maintaining voltage clamping functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If an RCD clamp circuit is used, then the diode prevents charge from flowing through the switching transistor channel, but the device size is relatively large due to component matching requirements

Engineering Contradiction:

Improveswitching transistor heat reductionVSAvoiddevice size

Core Design Contradiction:

TemperatureVSVolume of stationary object

Solution Approach 1:

The stabilivolt diode's reverse breakdown voltage is specifically selected to be lower than the switching transistor's withstand voltage but higher than the normal operating voltage. This parameter selection allows the RCD circuit components to be smaller while still providing effective protection, as they only need to handle the excess voltage above the breakdown point.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If an RCD clamp circuit is used, then the resistor discharges the capacitor, but the clamping effect is unstable due to residual voltage affecting turn-off spike voltage

Engineering Contradiction:

Improvecapacitor dischargeVSAvoidclamping effect stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The stabilivolt diode serves as a mediator that stabilizes the clamping effect by providing a consistent breakdown voltage reference. Regardless of the capacitor's residual voltage, the stabilivolt diode ensures that the clamping voltage remains stable at its breakdown point, eliminating the instability caused by varying residual voltages.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design effectively reduces the spike voltage at turn-off, enhances clamping reliability, and achieves a more stable clamping effect by using stabilivolt diodes to manage voltage spikes and leakage currents, thereby improving the overall performance and efficiency of the clamp circuit.

Implementation Method 1

when voltage between the first end and the second end of the switching transistor exceeds reverse breakdown voltage of the first stabilivolt diode, the first stabilivolt diode is turned on

Methodology Applied

Scientific EffectReverse breakdown voltage: Avalanche Breakdown

Implementation Method 2

The resistor is used for discharging the capacitor, to prevent continues rise of the capacitor voltage caused by charge accumulation

Methodology Applied

Scientific EffectEnergy dissipation: Joule Heating

Data Source

PatentUS11336274B2Clamp circuit and power module using the same

Publication Date: 2022.05.17 DELTA ELECTRONICS (SHANGHAI) CO LTD

AI summary

The present disclosure mainly provides a clamping circuit, coupled to a first end and a second end of a switching transistor through a first node and a second node, comprising: an RCD circuit, comprising a first resistor and a first capacitor connected in parallel between the second node and a third node, and a diode having a negative electrode coupled to the third node; and a first stabilivolt diode, having a negative electrode coupled to the first node and a positive electrode coupled to a positive electrode of the diode at a fourth node.