SiC BJT Research Articles

The First 4H-SiC BJT-Based 20 kHz, 7HP PWM DC-to-AC Inverter for Induction Motor Control Applications

This paper reports the design, fabrication and testing of the first 4H-SiC BJT-based, PWM DC-to-AC inverter at a record high power (7.4HP) and PWM frequency of 20 kHz with a bus voltage of 330V. Six 4H-SiC BJT switches and six 4H-SiC MPS diodes are used to form an all-SiC power board which is driven by a Si base driver, interfaced with a Si-based voltage source driver. The inverter has been used to control a GE three-phase AC induction motor of 7.5HP and has run up to an input power of 7.4HP (5.5kW). The SiC BJT I-V characteristics, the inverter switching waveforms and the inverter efficiency at different input power levels are presented.

SiC BJT Technology for Power Switching and RF Applications

SiC BJT Technology for Power Switching and RF Applications

SiC BJT's for High Power Switching and RF Applications

ABSTRACTIn this paper, high performance, high voltage NPN bipolar junction transistors in 4H-SiC are presented for applications in low frequency (< 5 MHz) power conversion systems as well as in RF (425 MHz) power amplifiers. The power BJTs for low frequency switching applications were designed to block 1300 V and showed a specific on-resistance of 8.0 mohm-cm2, which outperforms all SiC power switching devices ever reported. Moreover, these transistors show a positive temperature coefficient in the on-resistance and a negative temperature coefficient in the current gain, which enable easy paralleling of the devices. In addition, RF BJTs were designed, fabricated and tested for operation at UHF frequencies. The common emitter breakdown voltage was in excess of 500 V consistent with the 5 micron collector thickness. For VCC = 20 V, fT peaked at about 1.5 GHz. A single cell was measured in common emitter mode with a collector supply voltage of 80 V in class AB at 425 MHz. A 100 μs pulse width with 10% duty cycle was used. A maximum output power of 50 W for a single cell was achieved. The peak large signal power gain was 9.6 dB. The collector efficiency at the power output of 50 W was 51% with a power gain of 9.3 dB. This represents the first demonstration of a SiC RF BJT.

The 4H-SiC npn power bipolar junction transistor

The static and dynamic performance of the power silicon carbide BJT is investigated and compared with the silicon carbide UMOSFET by employing a numerical semiconductor simulator. The silicon carbide BJT exhibits superior current handling ability to and switching speed comparable with the SiC MOSFET in the voltage range simulated (1 kV-4 kV). The high current gain of the SiC BJT redresses the base drive problem of the silicon power BJT. It is proposed that research be carried out on the power silicon carbide NPN BJT, since it does not have the premature gate oxide breakdown and low inversion layer mobility problems associated with SiC MOSFET technology.