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MULTIPLE RLC RESONANT SURGE TESTER FOR SEMICONDUCTOR TESTING AND VALIDATION

IP.com Disclosure Number: IPCOM000244041D
Publication Date: 2015-Nov-07
Document File: 7 page(s) / 186K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and circuitry topology based on RLC resonant circuit for surge testing and validation of semiconductors is disclosed The circuitry and method disclosed herein is used to test high power semiconductors by reproducing single and multiple half sinusoid waveforms observed in a surge current event with variable amplitude and duration through a device under test

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MULTIPLE RLC-RESONANT SURGE TESTER FOR SEMICONDUCTOR TESTING AND VALIDATION

BACKGROUND

 

The present disclosure relates generally to surge current testing and more particularly to a method and circuitry topology based on RLC-resonant circuit for surge current testing and validation for semiconductors.

In various industrial applications, induction motors are usually fed via an inverter to produce mechanical characteristics desired by a user. Such inverter fed induction motors need a very accurate fault tolerant system for smooth operation. There are various technologies for fault analysis, monitoring and diagnosis of the inverter fed induction motors. These faults include the transistor failure, gate drive pulse failure, open inverter leg, DC link capacitor faults.  Microcontrollers and FPGA based control systems reduce failure probability for semiconductor components.

Capacitors are used in various power electronics applications including the inverters and Switch Mode Power Supply (SMPS) and capacitors are generally known to have failure probability of about 60%. Also, Equivalent Series Resistance (ESR) of the capacitor increases with passage of time. In some circuits, increasing ESR may not present a problem but when the capacitor is used in a switching circuit the ESR can combine with the switching frequency and cause self-heating, thereby indirectly leading to failure of capacitor.

Further, verifying stress on semiconductor devices is essential for a three phase inverter feeding an inductive load. Freewheeling diodes are connected in anti-parallel direction and provide a path for current to flow in same direction when motor inductance changes its polarity. In regular conditions current drawn by the motor is controlled by the state of switches and the generation of back e.m.f. If the back e.m.f. exceeds applied voltage, the motor starts behaving like a generator. If the terminal voltages become zero while the motor is running, the back e.m.f. becomes greater than the applied voltage. There are several reasons for terminal voltages to be zero for example, inverter output terminal open circuit, shut down of input supply and DC Link capacitor short circuit.

The problem of inverter output terminal open circuit may occur due to loose connection which hampers the operation and shuts down the motor making its speed zero. The shutdown of input supply makes the output voltage zero and for a little time the freewheeling diode will conduct and motor will stop depending upon the inertia of load. In case of a short circuit across a DC link capacitor output of inverter becomes zero making the back e.m.f. greater than the applied voltage. The induction motor starts behaving like an induction generator. A short circuit appears at the terminals of the motor via faulty DC link capacitor and draws current from the motor. The short circuit current is defined as surge current and has duration in the millisecond range. Such surge current passes through the swi...