An Improved Voltage Clamp Circuit Suitable for Accurate Measurement of the Conduction Loss of Power Electronic Devices

Abstract

Power electronic devices are essential components of high-capacity industrial converters. Accurate assessment of their power loss, including switching loss and conduction loss, is essential to improving electrothermal stability. To accurately calculate the conduction loss, a drain–source voltage clamp circuit is required to measure the on-state voltage. In this paper, the conventional drain–source voltage clamp circuit based on a transistor is comprehensively investigated by theoretical analysis, simulations, and experiments. It is demonstrated that the anti-parallel diodes and the gate-shunt capacitance of the conventional drain–source voltage clamp circuit have adverse impacts on the accuracy and security of the conduction loss measurement. Based on the above analysis, an improved drain–source voltage clamp circuit, derived from the conventional drain–source voltage clamp circuit, is proposed to solve the above problems. The operational advantages, physical structure, and design guidelines of the improved circuit are fully presented. In addition, to evaluate the influence of component parameters on circuit performance, this article comprehensively extracts three electrical quantities as judgment indicators. Based on the working mechanism of the improved circuit and the indicators mentioned above, general mathematical analysis and derivation are carried out to give guidelines for component selection. Finally, extensive experiments and detailed analyses are presented to validate the effectiveness of the proposed drain–source voltage clamp circuit. Compared with the conventional drain–source voltage clamp circuit, the improved drain–source voltage clamp circuit has higher measurement accuracy and working security when measuring conduction loss, and the proposed component selection method is verified to be reasonable and effective for better utilizing the clamp circuit.

Current Collapse Phenomena Investigation in Automotive-Grade Power GaN Transistors

“…This sensing network [20][21][22][23] consists of a MOSFET depletion transistor M, a resistor R, and a constant voltage V CC (Figure 4). The gate of M is connected to a fixed potential, so its source potential controls its working state.…”

“…This sensing network [20][21][22][23][24][25] combines the two previous networks, adding a few components such as two Schottky diodes D 1 , D 2 , and the resistor R 2 to limit the current that flows through the Zener diode D 3 (Figure 5). M is a MOSFET transistor; V CC , R 1 , and C are, respectively, a DC voltage source, a resistor and a capacitor that set the gate potential and the on-state transient of M.…”

“…The junction capacitance of D 1 is charged only by the V DSON , so the system frequency capability depends on how fast D 1 enters the blocking state. The Schottky diodes, the capacitor C and the resistor R 2 are designated to mitigate the voltage spikes, respectively providing a current freewheeling path and a slower transient to the off-state for M [20,23,24]. The amplitude of the spikes can also be reduced by increasing the V CC voltage, but at the cost of a higher clamping voltage.…”

“…The amplitude of the spikes can also be reduced by increasing the V CC voltage, but at the cost of a higher clamping voltage. Another important aspect to be considered when choosing the network's components is that they could easily work out of their safe condition (SOA) when the DUT is subjected to high voltages or it commutates at high frequency [23].…”

In-place Characterization of On-state Voltage for SiC MOSFETs: Controlled Shoot-through vs. Film Heater

“…In addition, since a high voltage swing occurs at the device drain as soon as it is turned on, a clamper circuit like that of [15,16] is used to guarantee sufficient resolution in the on-state voltage measurement.…”