Power Transistor Gate Voltage Monitoring for Short-Circuit Protection
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Solution Overview
Problem
Existing methods for monitoring and protecting power transistors like IGBT and MOSFET are bulky, energy-consuming, or specific to certain component types, failing to effectively detect short-circuit currents and integrity issues.
Innovation Solution
A compact power stage with a voltage sensor and capacitance measuring device at the gate of the transistor, coupled with an energy storage device and voltage reducer, to detect and manage short-circuit currents by monitoring gate voltage and capacitance, and applying additional voltage to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an isolated current sensor (transformer) is added to measure current at the collector terminal, then current measurement capability is improved, but the transistor size increases
Solution Approach 1:
The patent uses the gate terminal as an intermediary measurement point. Instead of directly measuring collector current with a transformer, the system measures gate voltage which indirectly reflects the conduction state and current flow through the transistor, thereby avoiding the need for additional sensing components at the collector terminal
Solution Approach 2:
The patent replaces the mechanical/electromagnetic transformer-based current sensing with an electrical voltage measurement approach. By monitoring gate voltage characteristics, the system substitutes direct current measurement with a voltage-based indirect measurement method that requires no additional bulky sensing components
2Measurement precision
If a resistor (shunt) is connected in series to measure current, then current measurement capability is improved, but energy consumption increases due to resistor dissipation
Solution Approach 1:
The patent replaces the resistive shunt measurement method with a voltage-based measurement at the gate terminal. This substitution eliminates the need for power-dissipating resistors in series with the current path, thereby reducing energy consumption while maintaining measurement capability through voltage sensing
3Ease of operation
If a current mirror circuit is integrated into the power component to measure collector current, then measurement access is improved, but device complexity and adaptation requirements increase
Solution Approach 1:
The patent extracts the measurement function from complex internal current mirror circuits and implements it through simple gate voltage monitoring. By taking out the measurement requirement from the internal transistor structure and addressing it through external gate voltage sensing, the system avoids the complexity of integrated current mirror circuits while maintaining measurement accessibility
Solution Approach 2:
The gate voltage monitoring approach serves multiple functions: it indicates conduction state, provides short-circuit detection capability, and enables current measurement all through a single measurement point. This universal approach replaces the specialized current mirror circuit with a multi-functional measurement method
4Measurement precision
If collector voltage is studied using a diode, then voltage measurement is improved, but the device size increases and short-circuit detection becomes blind during transition periods
Solution Approach 1:
The patent uses the gate terminal as an intermediary measurement point that provides continuous information about the transistor state. By monitoring gate voltage, the system gains insight into conduction state and short-circuit conditions without needing to directly measure collector voltage with additional diode components
Solution Approach 2:
The gate voltage inherently reflects the transistor's operational state and conduction level. The system leverages this self-indicating property of the gate voltage to obtain measurement information without requiring additional sensing components, thereby avoiding increased device size
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
Effectively detects and prevents short-circuit currents in power transistors, ensuring operational integrity through precise voltage and capacitance monitoring, reducing component size and energy consumption.
Implementation Method 1
a voltage sensor capable of detecting a voltage Vge at the level of the grid g of the power transistor outside a predefined voltage range
Implementation Method 2
an energy storage device configured to deliver an additional voltage to the grid g if the equivalent capacity of the grid Cge is unloaded
Implementation Method 3
the energy storage device is an inductor positioned between the driver and the grid g of the power transistor
Implementation Method 4
the power stage includes a voltage reducer capable of reducing the voltage Vge à the grid g up to a threshold voltage
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a power stage (2) comprising a power transistor (4) controlled via a driver (6), the power transistor (4) comprising three terminals including a collector c, an emitter e and a gate g connected to the driver (6), the power stage (2) comprising a detection device (8) for a short-circuit current cc between the collector c and the emitter e, the detection device (8) comprising a voltage sensor (82) capable of detecting a voltage Vge at the gate g of the power transistor (4) outside a predefined voltage range.