IGBT Gate Driver Circuit for In-Field Threshold and VCESAT Measurement
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Solution Overview
Problem
Conventional methods for condition monitoring of Insulated Gate Bipolar Transistor (IGBT) modules require dedicated test equipment and are not suitable for operational field settings, making it difficult to measure critical parameters like collector-emitter saturation voltage (VCESAT) and threshold voltage (VGTH) effectively.
Innovation Solution
A method and device that connect the collector of one IGBT to the emitter of another, allowing for in-field measurement of VCESAT and VGTH by operating the IGBTs in their forward linear region, adjusting gate voltage to change collector current, and using analog-to-digital converters to determine these parameters, thereby integrating condition monitoring into existing gate driver circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dedicated test equipment is used to measure VCESAT and VGTH, then measurement precision is improved, but device complexity and system cost increase
Solution Approach 1:
The patent combines the condition monitoring functionality into the existing gate driver circuit by integrating an analog-to-digital converter and processor. The gate driver's output stage is reused to apply gate voltage, and existing collector current control capabilities are leveraged, merging measurement functions with the driver circuit rather than using separate dedicated test equipment.
Solution Approach 2:
The gate driver circuit is designed to perform multiple functions: normal IGBT switching control and condition monitoring. The same circuit components (analog-to-digital converter, processor, gate voltage output) are used for both operational control and parameter measurement, eliminating the need for specialized single-function test equipment.
2Measurement precision
If dedicated test equipment is used for IGBT condition monitoring, then measurement capability is improved, but ease of operation in field settings deteriorates
Solution Approach 1:
The measurement functionality is merged into the gate driver circuit that is already present in the IGBT module. This integration allows the condition monitoring to be performed using the same circuitry used for normal operation, enabling field measurements without requiring external dedicated test equipment or module removal.
Solution Approach 2:
The IGBT module performs its own condition monitoring through the integrated gate driver circuit. The system uses its existing resources (gate voltage output, collector current control, analog-to-digital converter) to measure its own parameters, eliminating the need for external testing equipment and simplifying field operation.
3Measurement precision
If module removal is required for testing, then measurement precision is improved, but productivity and operational time are reduced
Solution Approach 1:
The IGBT module monitors its own condition in-situ without requiring removal from the system. The integrated gate driver circuit continuously or periodically measures VCESAT and VGTH parameters during normal operation, eliminating downtime associated with module removal and reinstallation for testing.
Solution Approach 2:
The condition monitoring occurs continuously or periodically during normal IGBT operation rather than requiring separate testing intervals. The gate driver circuit maintains its normal switching function while simultaneously performing measurements, ensuring uninterrupted operation and continuous health assessment.
4Measurement precision
If conventional separate measurement methods are used, then measurement capability is improved, but board space requirements increase
Solution Approach 1:
The condition monitoring circuitry is merged with the existing gate driver circuit on the same integrated circuit or circuit board. The analog-to-digital converter, processor, and measurement circuitry share the same physical space with the gate driver components, eliminating the need for separate dedicated measurement hardware and reducing overall board space requirements.
Data Source
AI summary
An isolated insulated gate bipolar transistor (IGBT) gate driver is provided which integrates circuits, in-module, to support the measurements of threshold voltage, and collector-emitter saturation voltage of IGBTs. The measured gate threshold and collector-emitter saturation voltage can be used as precursors for state of health predictions for IGBTs. During the measurements, IGBTs are biased under specific conditions chosen to quickly elicit collector-emitter saturation and gate threshold information. Integrated analog-to-digital converter (ADC) circuits are used to convert measured analog signals to a digital format. The digitalized signals are transferred to a micro controller unit (MCU) for further processing through serial peripheral interface (SPI) circuits.