May 2020

www.Finepower.com POWER GaN 17 www.power-mag.com Issue 2 2020 Power Electronics Europe and electric propulsion, the automotive industry is facing a massive transformation. IHS Markit estimates that 12 million cars will drive autonomously by 2035. According to Bloomberg New Energy, 32 million cars are expected to have electric drives by that year. Both trends will significantly increase the demand for power semiconductors. In the car, it is the innovative but power-hungry electronically controlled functions and features that require a 48 V power supply. These include start/stop systems, electric steering, and turbochargers, electronic chassis controls, and electronically controlled air conditioning, to name just a few examples. The intelligent control systems of (partially) autonomous vehicles also require sophisticated sensor technology such as lidar, radar, and cameras, as well as powerful graphics processors. All these systems increase the power consumption in the car. In particular GPUs are very energy-hungry and represent a major additional load on the car’s traditional 12 V power supplies. For 48 V automotive power systems, GaN technology increases the efficiency, shrinks the size, and reduces system cost (Figure 2). For applications in autonomous and assisted driving, where lidar systems serve as the “eyes” of the vehicles, very short laser pulses of the order of a few nanoseconds are used to achieve the required distance resolution. These pulses are typically generated by a laser diode. To achieve a sufficient range, the optical peak power must be high, i. e. current peaks of a few 10 A up to a few 100 A are involved. Until now, this has required complex circuits and exotic, expensive semiconductors. A typical lidar pulsed laser driver uses a semiconductor switch in series with the laser source and a power supply. Limiting factors for system performance are stray inductances and the speed of the semiconductor power switch. In recent years, low-cost GaN power FETs and ICs have come on the market that offer significantly lower inductance while providing switching frequencies up to 10 times higher than comparable Silicon MOSFETs. The advent of GaN FETs and ICs makes it possible to achieve the desired performance with simple, space-saving circuits at low cost. The greatly improved performance of GaN FETs compared to Silicon MOSFET technology results in much faster switching for a given peak current capability, enabling currents >100 A and pulse widths <2 ns with one laser load. Automotive electronics can now take full advantage of the improved efficiency, speed, smaller size, and lower cost of eGaN devices. EPC has a growing line of products that have achieved AEC Q101 qualification. To complete AEC-Q101 testing, these eGaN FETs had to undergo rigorous environmental and bias-stress testing. Of particular note is the fact that these wafer level chip-scale devices passed all the same testing standards created for convention packaged parts. GaN in precision motor drives Low cost, high-precision motor drives are finding expanding use in applications such as industrial automation, robotics, drones, and emobility such as scooters and ebikes. The brushless direct current (BLDC) motor offers these applications a lot of power in a small installation space, precise control, and a high electromechanical efficiency while generating only minimal vibrations. BLDC motors are driven by inverter circuits, most of which are multiphase and traditionally use MOSFETs. The higher switching speed of GaN FETs and ICs compared to Silicon MOSFETs allows the construction of converters with a much higher switching frequencies. This not only benefits efficiency, but also Figure 2: Efficiency comparison of eGaN FET vs. Silicon MOSFET in a 48 V to 12 V, 3 kW system Figure 3: Overview of a typical lidar system

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