APEC Highlights - Part Three

April 8, 2019 Alix Paultre

We’ve said how energetic the power industry demonstrated itself to be at the Applied Power Electronics Conference (APEC) this year in Anaheim. One of the reasons for this, beyond the sheer friendly camaraderie of the power community, is the amount of dynamic and disruptive change going on. This is being manifested in things from advanced materials like wide-bandgap (WBG) semiconductors, to newer, software-oriented power electronic topologies, to better and more accurate measuring technology. This rising tide is lifting and challenging all boats with the sudden increase in depth.

For example, the technology advantages of WBG put pressure on all aspects of a circuit, from the need for better magnetics and passives to the semiconductor packaging itself and the related interconnect technologies. These issues are being addressed in real time, and we are already looking forward to the advances we will see next month in Nuremberg at the Power Control and Intelligent Motion (PCIM) event. For now, though, here are some of the last of our APEC highlights.

SiC

More and more companies are coming out with Silicon Carbide (SiC) parts for challenging applications like automotive systems. Littelfuse introduced two second-generation, 650V, AEC-Q101-qualified SiC Schottky Diodes, offering negligible reverse recovery current, high surge capability, and a maximum operating junction temperature of 175°C.

Dissipating less energy and operating at higher junction temperatures mean smaller heat sinks and a smaller system footprint. Key benefits include lower switching losses than silicon bipolar diodes and fast, temperature-independent switching behavior. The LSIC2SD065DxxA Series SiC Schottky Diode comes in current ratings of 6A, 10A, or 16A in a TO 263-2L package; the LSIC2SD065ExxCCA Series SiC Schottky Diode is available with current ratings of 12A, 16A, 20A or 40A in a TO-247-3L package.

One announcement in SiC devices at APEC came from ROHM, who released 10 more automotive-grade SiC MOSFETs, the SCT3xxxxxHR series. Targeting demanding power applications like onboard chargers, these devices address the need of higher-voltage batteries to have power systems with low loss and higher withstand voltages.

Measurement

There is no precision without feedback, and precise current and voltage data from the high-voltage rails is needed to maximize efficiency and respond quickly to faults or changes in the load. Silicon Labs introduced a family of isolated analog amplifiers, voltage sensors and delta-sigma modulator (DSM) devices at APEC, designed to provide accurate current and voltage measurement with very low drift across temperature. 

Their Si89xx family provides flexible voltage, current, output, and package options to address industrial and green-energy applications such as EV battery management and charging systems, dc-dc converters, and motor, solar and wind turbine inverters. Silicon Labs’ third-generation isolation technology keeps controllers safe across wide temperature variations with a 1414V working voltage and 13kV bipolar surge, exceeding industry requirements.

The Si89xx devices’ 75 kV/µs immunity to fast transients ensures reliable and accurate current readings in demanding industrial applications. The Si89xx family also supports a fail-safe indication to the host controller if the high-side supply voltage is not detected.

Typical offset error is as low as ±40 µV, with a ±0.1 percent gain error, as well as a typical offset drift as low as ±0.15 µV/˚C and a typical gain drift as low as –6 ppm/˚C. The signal-to-noise ratio is up to 90 dB, and a low-power mode automatically reduces current draw on one side of the isolation barrier to approximately 1 mA whenever voltage is removed from the other side.

Looking Forward

The field of power electronics is a rapidly-moving target today, with new technology and tools to address the growing number of applications across the spectrum of society. With APEC in the rear-view mirror and PCIM (and other shows) on the horizon, traveling the road of embedded development is turning out to be a very entertaining and informative ride indeed.

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