Measurement method of flatband voltage of power semiconductor module

A measurement method of a flatband voltage of a power semiconductor module comprising at least one semiconductor element among a Metal-Oxide-Semiconductor element and a Metal-Insulator Semiconductor element during operational service, said method comprising:

• a. applying a bias voltage to said module such that said module switches from an off-state to an on-state, or from an on-state to an off-state;
• b. triggering a gate current Ig injection from a current source to a gate of the module when an initial gate-emitter/source voltage is equal to a flatband voltage Vfb,h of the module within +/−5V;
• c. measuring the voltage Vig across the current source;
• d. extracting of a flatband voltage Vfb,h+1 from the said measured voltage Vig across the current source
• e. stopping said gate current Ig injection
• when the absolute difference between the gate emitter/source voltage and the flatband voltage Vfb,h becomes superior to a predefined limit;
• or
• when the gate current Ig injection duration tinj exceeds a predetermined duration tmax;
• f. saving the extracted flatband voltage Vfb,h+1 value.