A GaN-HEMT Compact Model Including Dynamic RDSon Effect for Power Electronics Converters

Abstract

In order to model GaN-HEMT switching transients and determine power losses, a compact model including dynamic RDSon effect is proposed herein. The model includes mathematical equations to represent device static and capacitance-voltage characteristics, and a behavioural voltage source, which includes multiple RC units to represent different time constants for trapping and detrapping effect from 100 ns to 100 s range. All the required parameters in the model can be obtained by fitting method using a datasheet or experimental characterisation results. The model is then implemented into our developed virtual prototyping software, where the device compact model is co-simulated with a parasitic inductance physical model to obtain the switching waveform. As model order reduction is applied in our software to resolve physical model, the device switching current and voltage waveform can be obtained in the range of minutes. By comparison with experimental measurements, the model is validated to accurately represent device switching transients as well as their spectrum in frequency domain until 100 MHz. In terms of dynamic RDSon value, the mismatch between the model and experimental results is within 10% under different power converter operation conditions in terms of switching frequencies and duty cycles, so designers can use this model to accurately obtain GaN-HEMT power losses due to trapping and detrapping effects for power electronics converters.

A Fast and Accurate GaN Power Transistor Model and Its Application for Electric Vehicle

“…Therefore, conduction losses due to dynamic R dson can be modelled. In each cell, voltage increase (τ off i ) and decrease rate (τ on i ) are modelled by a RC circuit to represent the lifetime of the trapped charge, which is from our previous work [26] and is given below.…”

An Overview of Strengths and Weaknesses in Using MOSFET Experience for Modeling GaN HEMT

“…Therefore, the successful adoption in the GMOS block of MOSFET models for GaN HEMTs and vice versa confirms the usefulness of exploiting the wide MOSFET circuit modeling experience for developing the GMOS block when the temperature variation can be neglected. Another GaN HEMT model of the GMOS that does not account for the dependence on temperature has been developed by GaNSystem [31]:…”

“…Only the following equations have been proposed for GaN HEMT so far. A model without any temperature-dependence term that emulates the TQ current has been developed by GaNSystem [31]:…”

“…According to Figure 4H, ( 18) enables a satisfactory average error, but the maximum is not negligible. In [31], a more complex equation that contains three hyperbolic tangent functions and 10 fitting parameters has been presented:…”

“…In [31], a modeling approach that accounts for soft switching has been proposed. In this case, the off-time, duty cycle, and partially frequency have been considered, but the temperature and load conditions have been neglected.…”