A power conversion device including a switching element includes: a temperature change estimation unit estimating temperature change in a semiconductor chip containing the switching element; a number calculator calculating the number of power cycles to fracture of the semiconductor chip due to power cycles; and a degradation degree calculator computing a degree of degradation of the semiconductor chip caused by the power cycles. The temperature change estimation unit calculates a maximum value and a minimum value of temperature of the semiconductor chip in one power cycle based on a first threshold of temperature fall allowed when it is determined that the temperature of the semiconductor chip is rising, and a second threshold of temperature rise allowed when it is determined that the temperature of the semiconductor chip is falling. The number calculator calculates the number of power cycles to fracture based on the maximum value and the minimum value.

The present invention provides a system and method for measuring intermittent operating life (IOL) of a GaN-based device under test (DUT) is provided. The system is operable in a stressing mode, a cooling mode and a measure mode. A power regulation approach is adopted to ensure that DUT of the same thermal resistance have same temperature increase during the IOL test. The present invention eliminates the influence caused by parasitic parameters of testing circuits and the inconsistency of threshold voltage and drain-source resistance of the device itself. Through power regulation, it is the junction temperature of the device, not the housing temperature of the device, being directly controlled. Therefore, higher measurement accuracy can be achieved.

A detection circuit for open, close and suspension states of a high and low level effective switch in a vehicle. The circuit includes an optocoupler circuit module, a low-level active path module, a high-level active path module, a filtering and debouncing module, a transient suppression module, and a wiring terminal. The optocoupler circuit module is connected to the low-level active path module, the high-level active path module and the low-level active path module are connected in parallel to the filtering and debouncing module, and the filtering and debouncing module is connected to the transient suppression module, and then connected to the external high-level active switch or low-level active switch through the wiring terminal. Whether it is a high-level active switch or a low-level active switch, the detection circuit can distinguish whether the switch is in the closed or suspended state, and the strong and weak voltages are isolated.

Provided is a test method of a semiconductor device under test, the test method comprising: controlling the semiconductor device under test to an on state by inputting a control signal to the semiconductor device under test; and observing the semiconductor device under test at a time of controlling the semiconductor device under test in the on state to an off state and evaluating the semiconductor device under test, wherein the semiconductor device under test includes one semiconductor device under test or a plurality of semiconductor devices under test, and in the controlling to the on state, a length of an on-time for which the one semiconductor device under test or the plurality of semiconductor devices under test are set to the on state is adjusted based on a magnitude of a variation in a delay time of the control signal.

A method for identifying a malfunctioning current sensor in an electrical apparatus, in which an electrical power supply of the electrical apparatus is at least partly supplied by a switched-mode electrical power supply circuit connected to at least one current sensor which samples an electrical current in a phase conductor of an electrical installation, the power supply circuit delivering a regulated electrical voltage, the method including: determining a switching duty cycle of a power switch of the switched-mode electrical power supply; analysing the determined switching duty cycle; and identifying a failure condition if the behaviour of the switching duty cycle is representative of a malfunctioning of at least one of the current sensors.

A front-end device for monitoring operation of an associated electric power device with semiconductor power switches generating a power output, e.g. a three-phase power output. The front-end device has input terminals arranged for connection to the electric phase(s) of the power output of the associated electric power device, and an electric circuit connected to the input terminals and connected to at set of output terminals. The electric circuit has a passive interconnection comprising electric semiconductor switches and diodes. The electric circuit serves to electrically block any high voltage component from the input terminals from reaching the output terminals, while allowing an on-state voltage of at least one semiconductor power switch in the associated electric power device to pass to the at least two output terminals. The front-end allows low voltage equipment to be connected to its output terminals for determining an on-state voltage of switches of the electric power device. Especially, embodiments with self-powered reference voltage circuits provided by zener diodes allow compact low cost versions for use in e.g. portable test equipment or as part of permanently installed health condition monitoring of power devices. The front-end device can be used as a simple and low cost solution for non-invasive health condition monitoring of power devices, e.g. power converters in such as power electric generation system or electric vehicles. Such monitoring allows predictive maintenance to be performed to avoid any faults in the power device that may cause permanent damages.

A method of monitoring the health of a semiconductor power electronic switch such as an insulated gate bipolar transistor (IGBT) is provided. The method having the steps of: measuring one or more parameters selected from the group consisting of: a rate of change of voltage

[00001]$\left(\frac{\mathrm{dV}}{\mathrm{dt}}\right)$

across the switch; a rate of change of current

[00002]$\left(\frac{\mathrm{di}}{\mathrm{dt}}\right)$

through the switch, a charge present on a gate of the switch (Q.sub.G), a peak overshoot voltage (V.sub.PO) across the switch, and a peak overshoot or reverse recovery current (I.sub.RR) through the switch; and estimating the health of the switch based on the measured parameter(s).

Provided is a testing apparatus for testing a semiconductor device including a first main terminal to which a first power source voltage is applied and a second main terminal to which a second power source voltage is applied, comprising: a condition setting unit for setting a changing speed of a terminal voltage of the first main terminal at turn-off of the device; an operation controlling unit for turning off the device under a condition set by the condition setting unit; and a determining unit for screening the device based on an operation result of the device, wherein: a time waveform of the terminal voltage at turn-off of the device includes a maximum changing point where a changing speed becomes maximum; and the condition setting unit sets the changing speed at a first set voltage higher than a voltage at the maximum changing point, to a predetermined value.

An apparatus provides precision measurement of voltage drop across a semiconductor switching element of a subsea device. The apparatus includes (a) a first circuit path having a first protective element, a first impedance element and a voltage source, wherein the first circuit path is configured to be connected between the first terminal and the second terminal of the semiconductor switching element, (b) a second circuit path formed between a first output terminal and a second output terminal, the second circuit path having a second protective element and a second impedance element, wherein the second protective element is identical to the first protective element, and wherein the second impedance element is identical to the first impedance element, and (c) a regulating circuit configured to regulating the current in the second circuit path such that said current in the second circuit path is equal to the current in the first circuit path, wherein the voltage drop between the first terminal and the second terminal of the semiconductor switching element equals the difference between the voltage provided by the voltage source and the voltage drop between the first output terminal and the second output terminal.

Disclosed examples include systems to determine an on-state impedance of a high voltage transistor, and measurement circuits to measure the drain voltage of a drain terminal of the high voltage transistor during switching, including an attenuator circuit to generate an attenuator output signal representing a voltage across the high voltage transistor when the high voltage transistor is turned on, and a differential amplifier to provide an amplified sense voltage signal according to the attenuator output signal. The attenuator circuit includes a clamp transistor coupled with the drain terminal of the high voltage transistor to provide a sense signal to a first internal node, a resistive voltage divider circuit to provide the attenuator output signal based on the sense signal, and a first clamp circuit to limit the sense signal voltage when the high voltage transistor is turned off.