Adaptive Gate Voltage Control in Power Transistor Modules

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Solution Overview

Problem

Power transistor modules using wide band-gap semiconductors like SiC MOSFETs face a trade-off between performance and lifetime due to the impact of gate voltage on conduction loss and dielectric layer lifetime, with higher gate voltages improving performance but reducing dielectric layer lifetime, and lower gate voltages extending dielectric layer lifetime but increasing on-resistance and switching losses.

Innovation Solution

A power transistor module with a control circuit that adjusts the gate voltage based on output power, applying a higher gate voltage for high output power to reduce on-resistance and conduction loss, and a lower gate voltage for low output power to extend dielectric layer lifetime and reduce power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a higher gate voltage is applied to the power transistor device, then the on-resistance is reduced and conduction loss decreases, but the lifetime of the gate dielectric layer is reduced

Engineering Contradiction:

Improveconduction lossVSAvoidgate dielectric layer lifetime

Core Design Contradiction:

Loss of energyVSDuration of action of stationary object

Solution Approach 1:

The control circuit dynamically adjusts the gate voltage based on the output power of the power transistor module. When output power is high, a higher gate voltage is applied to reduce on-resistance and conduction loss. When output power is low, a lower gate voltage is applied to extend gate dielectric layer lifetime. This dynamic adjustment resolves the contradiction by adapting the gate voltage to actual operating conditions rather than using a fixed voltage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the gate voltage parameter according to the output power level. The control circuit monitors output power and adjusts the gate voltage parameter accordingly - increasing it when high power is needed (to reduce conduction loss) and decreasing it when low power is needed (to protect dielectric layer lifetime). This parameter change strategy directly addresses the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If a higher gate voltage is applied to the power transistor device, then the current density increases and switching loss decreases, but the electrical field on the gate dielectric layer increases reducing its lifetime

Engineering Contradiction:

Improveswitching lossVSAvoidgate dielectric layer lifetime

Core Design Contradiction:

Loss of energyVSDuration of action of stationary object

Solution Approach 1:

The control circuit dynamically adjusts the gate voltage based on output power requirements. During high-power operation, a higher gate voltage is applied to increase current density and reduce switching loss. During low-power operation, a lower gate voltage is applied to reduce electrical field stress on the gate dielectric layer and extend its lifetime. This dynamic control resolves the contradiction between switching loss and dielectric layer lifetime.

Inventive Principle:

Principle #15Dynamics

3Duration of action of stationary object

If a lower gate voltage is applied to the power transistor device, then the gate dielectric layer lifetime is extended, but the on-resistance increases and conduction loss increases

Engineering Contradiction:

Improvegate dielectric layer lifetimeVSAvoidconduction loss

Core Design Contradiction:

Duration of action of stationary objectVSLoss of energy

Solution Approach 1:

The control circuit implements dynamic gate voltage adjustment based on output power monitoring. When the power transistor module operates at high output power, the control circuit applies a higher gate voltage to maintain low on-resistance and minimize conduction loss. When operating at low output power, it applies a lower gate voltage to extend gate dielectric layer lifetime. This dynamic adaptation eliminates the need to permanently compromise between these conflicting requirements.

Inventive Principle:

Principle #15Dynamics

4Use of energy by moving object

If a lower gate voltage is applied to the power transistor device, then power consumption is reduced, but the on-resistance increases reducing efficiency

Engineering Contradiction:

Improvepower consumptionVSAvoidconduction loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The control circuit dynamically adjusts gate voltage based on output power to optimize the balance between power consumption and conduction loss. At high output power levels, a higher gate voltage is applied to minimize conduction loss, which is the dominant loss mechanism. At low output power levels, a lower gate voltage is applied to reduce power consumption, as the absolute conduction loss is smaller. This dynamic strategy optimizes overall energy efficiency across different operating conditions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11489521B2Power transistor module and controlling method thereof

Publication Date: 2022.11.01 FAST SIC SEMICON INC

AI summary

A power transistor module includes a power transistor device and a control circuit. The control circuit is electrically connected to the power transistor device for providing at least one gate voltage to drive the power transistor device, and adjusting the at least one gate voltage in response to an output power of the power transistor module. When the output power is greater than a predetermined power load, the at least one gate voltage has a first swing amplitude; and when the output power is less than or equal to the predetermined power load the at least one gate voltage has a second swing amplitude less than the first swing amplitude.