Power Transistor Gate-Voltage Short-Circuit Detection
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Solution Overview
Problem
Existing methods for detecting short-circuit currents in power transistors are either bulky, energy-consuming, or require specific adaptations, making them inefficient and costly for reliable operation.
Innovation Solution
A compact power stage with a detection device that uses a voltage sensor to monitor the gate voltage of a power transistor, an energy storage device to deliver additional voltage when the gate capacitance is discharged, and a voltage reducer to manage the gate voltage and switch off the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an insulated current sensor is added at one of the two terminals of the power transistor, then the current passing through the terminal can be directly evaluated, but the volume of the transistor is increased
Solution Approach 1:
The patent uses the gate voltage as an intermediary parameter to indirectly detect the collector-emitter current. Instead of directly measuring the current through the power transistor terminals, the system measures the gate voltage which correlates with the current state, thereby avoiding the need for additional current sensors and reducing overall device volume
Solution Approach 2:
The patent replaces the physical current sensor (mechanical/electrical component) with an electrical measurement approach using existing gate voltage signals. By substituting direct current measurement with voltage-based indirect measurement, the system eliminates the need for additional sensor components
2Measurement precision
If a resistor is positioned in series with one of the two terminals to measure current, then the current can be measured, but the energy consumption is increased due to power dissipation
Solution Approach 1:
The patent replaces the resistive measurement method (which dissipates power) with a voltage-based measurement approach using the existing gate driver circuitry. The gate voltage measurement requires no additional power-dissipating components, thereby eliminating the energy loss associated with series measurement resistors
3Ease of operation
If a current mirror is incorporated in the power component to measure collector current, then access to the current value is simplified, but large investment in terms of adaptation is required
Solution Approach 1:
The patent makes the gate voltage measurement approach universal and applicable to different power transistor configurations without requiring specific adaptation. The method works with standard IGBT and MOSFET structures using existing gate driver circuits, eliminating the need for complex current mirror implementations or specialized component designs
4Reliability
If voltage at the collector is studied via a diode, then the detection can be performed, but the bulk is increased and detection is blind during off/on transition
Solution Approach 1:
The patent uses gate voltage as an intermediary that provides continuous information about the transistor state including during switching transitions. The gate voltage remains a reliable indicator throughout the entire operating cycle including off/on transitions, unlike collector voltage which is blind during transitions
Solution Approach 2:
The gate voltage measurement provides continuous detection capability throughout the entire switching cycle including during off/on transitions. The measurement is not interrupted or blinded during state changes, ensuring continuous monitoring of the transistor health status
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 solution allows for efficient detection and management of short-circuit currents, preventing component degradation and ensuring reliable operation with reduced bulk and energy consumption.
Implementation Method 1
a voltage sensor capable of detecting a voltage Vge at the gate g of the power transistor
Implementation Method 2
if the equivalent capacitance of the gate Cge is discharged
Implementation Method 3
an energy storage device configured to deliver an additional voltage to the gate g
Data Source
AI summary
A power stage includes a power transistor controlled via a driver, the power transistor comprising three terminals, including a collector c, an emitter e and a gate g linked to the driver, the power stage comprising a detection device for detecting a short-circuit current cc between the collector c and the emitter e, the detection device comprising a voltage sensor capable of detecting a voltage Vge at the gate g of the power transistor outside of a predefined voltage range.