This paper presents an analysis of single discrete silicon carbide (SiC) JFET and BJT devices and their parallel operation. The static and dynamic characteristics of the devices were obtained over a wide range of temperature to study the scaling of device parameters. The static parameters like on-resistance, threshold voltage, current gains, transconductance, and leakage currents were extracted to show how these parameters would scale as the devices are paralleled. A detailed analysis of the dynamic current sharing between the paralleled devices during the switching transients and energy losses at different voltages and currents is also presented. The effect of the gate driver on the device transient behavior of the paralleled devices was studied, and it was shown that faster switching speeds of the devices could cause mismatches in current shared during transients.
This paper presents an analytical approach for evaluating the magnet eddy-current losses of interior permanent-magnet synchronous machines (IPMSMs) during flux weakening. To investigate the magnet eddy-current losses, an analytical method of the time-varying magnetic flux density in the magnet is proposed based on the armature reaction magnetic field analysis. According to the time-varying magnetic flux density, a coefficient is used to evaluate the magnet eddy-current losses during flux weakening. The coefficient can indicate how the major design parameters in an IPMSM affect magnet eddy-current losses during flux-weakening operation. Finite-element analysis was used to validate the proposed model and calculate the magnet eddy-current losses of IPMSM with different design parameters.
In order to take full advantage of SiC semiconductor devices, high temperature device packaging needs to be developed. The potential defects in design and fabrication procedure are detailed and their detection steps in the electrical evaluation are presented. The established systematic testing procedure can rapidly detect defects and reduce the risk in high temperature packaging testing. The multi-chip module development procedure is also presented and demonstrated with an example.
Along with the rapid growth in electric vehicle (EV) market, higher power density and more efficient motor drive inverters are required. It is well known that silicon carbide (SiC) has advantages of high temperature, high efficiency and high switching frequency. It is believed that the appropriate utilization of these merits can pave the way to ultra-high power density inverters. This paper presents issues about SiC chip's current-carrying capability enhancement which is crucial for a compact inverter of tens and hundreds of kilowatts. Technical approaches towards ultra-high power density EV inverter including SiC module packaging, dc-link capacitor function analysis and system level integration are discussed. Different PWM algorithms which may improve efficiency and help to reduce the inverter volume are also studied.
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