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M. Bellini, ABB Corporate Research, MOS-AK workshop, ESSDERC, Lausanne 2016
Use and extraction of compact models for EMI / EMC simulations of power devices
Slide 2 © ABB
• Motivation • Physics of Power Diodes • Review of Existing Models • Improved Model Power Diode Model • IGBT Model and Parameter Extraction • Results and Discussion
Motivation
Slide 3 © ABB
• Accurate and fast compact model needed for predictive EMI/EMC simulations. No clear standard power diode models. Parameter extraction is very complex, because of coupled phenomena.
• The proposed diode model can accurately simulate reverse recovery in 120 ms, in contrast with 5-10 s for FEM SPICE models and 2-10 minutes for TCAD.
• The SCR expansion and the excess charge simulated by the circuit model agree closely to calibrated TCAD simulations. But the high precision in reverse recovery is obtained at the expense of DC characteristics (less important for EMI/EMC).
Requirements & Motivation
Slide 4 © ABB
Typically used by designers: • PSPICE • Simmetrix (Verilog-A)
Being evaluated at CRC: • Xyce • Qucs
Requirements: • GUI, device library (Verilog A) • Command line operation (model fitting) • Model / Circuit convergence debugging capability
Typical simulation tools
Slide 5 © ABB
Power Diodes: Characteristics
Device under test:
VRRM 4500 [V] IFAV 1650 [A] Electron irradiation
Energy
Dose
1-5
5-20
[MeV]
[kGy]
He irradiation
Energy
Dose
5-12
1010-1011
[MeV]
[cm-2]
Slide 6 © ABB
Power Diodes: Structure and Physics
The depth of the semiconductor is used to sustain the applied voltage. The maximum doping is limited by the cosmic ray failure mechanism.
anode
cathode
The bulk region of the semiconductor is chosen with the appropriate n- doping, which is generally in the 1013 cm-3 range The p+ and n+ contact are diffused at the top and bottom of the wafer.
Slide 7 © ABB
Power Diodes: Structure and Physics
Modulation reduces the on-state voltage drop to a few volts for currents of thousand Ampere. However, excessive charge storage in the drift region leads to very high switching losses.
2
2
dxpdDp
dtdp
+−=τ Ambipolar Diffusion Equation (ADE)
Slide 8 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements
Slide 9 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements
Slide 10 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements
Slide 11 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements
Slide 12 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements Switching circuit used for measurements
Slide 13 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements
Slide 14 © ABB
Power Diodes: Structure and Physics
Switching circuit used for measurements
Slide 15 © ABB
• e.g. FLECS
• Lookup table models
• can only describe voltage drops and commutation losses
• no transient behavior
• very widely used for system-level simulation
Modelling Approaches Functional Models
October 6, 2016
Slide 16 © ABB
• e.g. Hefner, Kraus
• Physical
• Few parameters (doping, thickness, lifetime, transit time)
• Limited to moderate accuracy àcomplexity of the approximation and implementation
• Accurate models have typically convergence or speed problems
Modelling Approaches Approximate Solution Models (Physical Models)
October 6, 2016
Approximate solution of the Ambipolar Diffusion Equation (ADE)
2
2
dxpdDp
dtdp
+−=τ
Slide 17 © ABB
• e.g. Strollo, Bryant
• Physical behavior
• Better accuracy but implementation in circuit simulators (if implemented with RC networks it can cause convergence degradation)
• Possible oscillation / series truncation problems
Modelling Approaches Laplace Transform Models
October 6, 2016
( ) ( )ttxpp
xtxpD
∂
∂+=
∂
∂ ,,2
2
τ
( ) ( ) ( )( ) ⎟
⎟⎠
⎞⎜⎜⎝
⎛
−
−=∑
∞
=12
10
cos,xxxxktptxp
k kπ
x1 and x2 are the boundaries of the modulated region.
Slide 18 © ABB
• e.g. Ma, Lauritzen
• Physical behavior, potential for good accuracy
• Very high speed: it’s possible to simulate large circuits
• Very good convergence properties
• Parameter extraction can be quite challenging
Modelling Approaches Lumped Charge Models
October 6, 2016
Slide 19 © ABB
Modelling Approaches Numerical Solution Models (FE, FD)
October 6, 2016
• e.g. Buiatti
• Potential for very high accuracy
• Very low speed: Only small circuits can be simulated
• Circuit simulators are not the best tools for FD or FE models: use of a TCAD simulator can improve precision / speed
• Parameter extraction can be extremely challenging
Slide 20 © ABB
Lumped Charge Model Ma-Lauritzen Model Derivation
October 6, 2016
Slide 21 © ABB
Avalanche generation is introduced in the model. The simplification are balanced by a field dependent recombination rate.
Lumped Charge Model Extended Ma-Lauritzen Model Derivation
October 6, 2016
Slide 22 © ABB
The multi-objective genetic algorithm NSGA-II is used to identify the optimal tradeoff between DC and RR (Pareto Frontier).
Parameter Extraction Procedure Multi-objective genetic algorithm to automate parameter extraction
October 6, 2016
8 parameters, 2 objectives
Slide 23 © ABB
Excellent accuracy in RR (good for EMI simulations). DC shows excessively resistive behavior.
Results: DC and Reverse Recovery Comparison with measured electrical characteristics
October 6, 2016
Slide 24 © ABB
The width of the SCR and the excess charge closely match calibrated TCAD.
Results: Internal Parameters Match with internal quantities calculated by TCAD
October 6, 2016
Slide 25 © ABB
Parameter Extraction/Fitting Procedure Multi-objective genetic algorithm to automate parameter extraction
October 6, 2016
Optim
izer - Measurement - Simulation
The optimizer varies the model parameters’ until the F.O.M. confirms that simulation matches data.
Slide 26 © ABB
IGBT-DIE 5SMY 12K1721, Ic = 100 A, Multiobjective optimization: 5 targets, 14 parameters
Parameter Extraction Procedure Multi-objective genetic algorithm to automate parameter extraction
October 6, 2016
Gat
e ch
arge
Tu
rn-o
n Ic
O
n-st
ate
trans
fer
Turn
off
Vce
The model scales well with the load current
Good agreement with the remaining characteristics
Slide 27 © ABB
Line impedance stabilization network can be simulated in half time and without convergence issues on a circuit with 70’000 variables.
Results: System EMI/EMC simulations Low Voltage AC Drive Noise Simulations incl. cable models
October 6, 2016
Slide 28 © ABB
• Wide variety of users / applications • Both GUI and command line operation desired • Verilog A integration necessary to model a variety of components • Debugging capability could dramatically shorten model development
time
Conclusions
October 6, 2016
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