How SiC-IGBTs Perform in an AGPU System

SiC-IGBTs can be utilized in numerous applications, from AC motor drives and three-phase inverters to AC motor drives and three-phase inverters. Their advantages include high efficiency and minimal switching loss while simultaneously helping reduce component size.

In order to evaluate their operating performance, we designed an experimental system. As a result, results revealed that these new switches could increase efficiency of traditional AGPU systems.

Cost

Cost is often a determining factor in power converter applications. Silicon carbide (SiC) devices offer significant cost advantages over their Si-IGBT counterparts, making them attractive options for high-efficiency and high-speed motor drives due to their lower manufacturing cost and increased switching frequency capabilities that enable better performance and power density than standard Si-IGBTs.

Selecting an efficient gate-driver circuit is central to reducing converter cost. A good gate driver circuit should feature low inductance to reduce voltage overshoot and ringing due to stray inductance; additionally, it must withstand high current loads while providing sufficient galvanic isolation between itself and the load.

Designers looking to reduce costs must select an optimal gate-driver design and switching frequency. An optimal frequency should be as low as possible without producing bulky filter components, according to research on SiC-IGBT and Si-IGBT converters at different wind speeds and 30kHz and 3kHz switching frequencies; efficiency was greater for SiC-IGBT at higher wind speeds – though this was counterbalanced by higher costs and volumes associated with siC-IGBT converters.

Performance

SiC-IGBT devices boast superior efficiency and power density compared to traditional Si-based devices, as well as lower device losses and operating temperatures that make them suitable for high performance applications such as motor drives. To maximize their performance, these devices must operate at higher switching frequencies; so the purpose of this paper is to examine how SiC-IGBTs perform in an AGPU system.

Experimental work involved using a 62 mm, 400A, 1.2kV Si-IGBT module comprising DC link capacitors, inverter-side inductor, forced air-cooled heat sink, gate drivers with protection logic and sensors as well as voltage and current measurements using both handheld oscilloscopes (MICsig 200MHZ handheld multifunctional oscilloscope and Hantek UT201 clamp meter), gate-to-emitter voltage and overshoot current measurements respectively; results demonstrated that SiC-IGBTs had shorter switching durations than their traditional counterparts (Figure 4).

SiC-IGBT inverters demonstrated low switching loss with 2 A loads. Their collector-to-emitter voltage transient response analysis also demonstrated this fact: turn-on gate resistance decreased as load current increased; however, turn-off gate resistance increased as load current did, leading to large overshoot current and voltage waveform ringing. Passive component volumes such as inductor volumes on either grid side (grid-side inducor volumes were calculated), capacitor volumes and filter volumes were all evaluated and compared; these results indicated that SiC IGBT converter had lower total volumes than traditional Si-IGBT converter.

Efficiency

SiC-IGBTs in AGPU systems can significantly increase their efficiency by replacing traditional Si transistors with SiC transistors. This can be accomplished by lowering overall system losses and speeding up switching speeds; for instance by decreasing their resonant frequency, increasing turn-off delay time, or using gate drivers with reduced stray inductance.

In this paper, the performance of SiC-IGBT modules used in AGPU-based power conversion systems is investigated. Three experimental systems were designed and created: traditional AGPU system, single pulse test (SPT) system and three phase inverter. Their results are then compared and analyzed to compare differences in operating performance between Si-IGBTs and SiC-IGBT modules.

An exhaustive hard switching behavior comparison was conducted using 1200-V Si-IGBT and SiC-IGBT modules, with results showing that SiC-IGBTs possess lower resonant frequencies, lower overshoot current and reduced switching losses than Si-IGBTs. Turn-on characteristics for both types of power devices were also compared, showing that SiC-IGBTs had shorter turn-on delay time and lower resonant frequencies than Si-IGBTs.

SiC-IGBTs rely on having low turn-on gate resistance as a key element of their successful operation, as fast charging of their gate-to-emitter voltage requires fast charge times. External turn-on/off gate resistors must have low inductance values so as to reduce any ringing caused by stray inductances and prevent any potential ringing effects.

Säkerhet

SiC MOSFETs’ higher switching frequencies help reduce diode and gate driver losses, increasing overall converter efficiency. Furthermore, these MOSFETs may be less susceptible to high energy particle induced failures caused by three main factors – device material type, surface area of device and voltage stress – with wider band gaps and smaller device sizes making them less vulnerable.

SiC MOSFETs were evaluated against standard silicon (Si) IGBTs to compare their performance as converter components. The results revealed that SiC devices reduced power losses for a typical 3-phase SPWM 2-level inverter by nearly 10 fold; raising switching frequency also helped significantly lower inductor weight by 68% resulting in significant savings off total converter weight.

This study compares the components of a grid-tied 190 kVA 2L-VSC comprising of SiC-MOSFETs and Si-IGBTs designed for use on a 690 V grid, including DC-Link and grid side LCL-Filter designs using SiC-MOSFETs as part of an LCL filter design for 690V grid. Comparison is made based on experimental characterization of switching behavior as well as data sheet values demonstrating on-state behavior; siC-MOSFETs feature reduced switching losses as well as reduced current de-rating at high temperatures; making them ideal for industrial applications where stable power output is key.