Use and extraction of compact models for EMI / EMC simulations of power devices

Transcription

1 M. Bellini, ABB Corporate Research, MOS-AK workshop, ESSDERC, Lausanne 2016 Use and extraction of compact models for EMI / EMC simulations of power devices

2 Motivation Motivation Physics of Power Diodes Review of Existing Models Improved Model Power Diode Model IGBT Model and Parameter Extraction Results and Discussion Slide 2

3 Requirements & Motivation 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). Slide 3

4 Typical simulation tools 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 Slide 4

5 Power Diodes: Characteristics Device under test: V RRM 4500 [V] I FAV 1650 [A] Electron irradiation Energy Dose He irradiation Energy Dose [MeV] [kgy] 5-12 [MeV] [cm -2 ] Slide 5

6 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 cm -3 range The p+ and n+ contact are diffused at the top and bottom of the wafer. Slide 6

7 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. dp dt 2 p d p = + D 2 Ambipolar Diffusion Equation (ADE) τ dx Slide 7

8 Power Diodes: Structure and Physics Switching circuit used for measurements Slide 8

9 Power Diodes: Structure and Physics Switching circuit used for measurements Slide 9

10 Power Diodes: Structure and Physics Switching circuit used for measurements Slide 10

11 Power Diodes: Structure and Physics Switching circuit used for measurements Slide 11

12 Power Diodes: Structure and Physics Switching circuit used for measurements Switching circuit used for measurements Slide 12

13 Power Diodes: Structure and Physics Switching circuit used for measurements Slide 13

14 Power Diodes: Structure and Physics Switching circuit used for measurements Slide 14

15 Modelling Approaches Functional Models e.g. FLECS Lookup table models can only describe voltage drops and commutation losses no transient behavior very widely used for systemlevel simulation October 6, 2016 Slide 15

16 Modelling Approaches Approximate Solution Models (Physical Models) Approximate solution of the Ambipolar Diffusion Equation (ADE) dp dt 2 p d p = + D τ 2 dx 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 October 6, 2016 Slide 16

17 Modelling Approaches Laplace Transform Models ( x, t) p p( x t) p D 2 = +, 2 x τ t p ( x, t) p ( t) = k= 0 k π cos k( x x ) 1 ( x ) 2 x1 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 x 1 and x 2 are the boundaries of the modulated region. October 6, 2016 Slide 17

18 Modelling Approaches Lumped Charge Models 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 October 6, 2016 Slide 18

19 Modelling Approaches Numerical Solution Models (FE, FD) 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 October 6, 2016 Slide 19

20 Lumped Charge Model Ma-Lauritzen Model Derivation October 6, 2016 Slide 20

21 Lumped Charge Model Extended Ma-Lauritzen Model Derivation Avalanche generation is introduced in the model. The simplification are balanced by a field dependent recombination rate. October 6, 2016 Slide 21

22 Parameter Extraction Procedure Multi-objective genetic algorithm to automate parameter extraction The multi-objective genetic algorithm NSGA-II is used to identify the optimal tradeoff between DC and RR (Pareto Frontier). 8 parameters, 2 objectives October 6, 2016 Slide 22

23 Results: DC and Reverse Recovery Comparison with measured electrical characteristics Excellent accuracy in RR (good for EMI simulations). DC shows excessively resistive behavior. October 6, 2016 Slide 23

24 Results: Internal Parameters Match with internal quantities calculated by TCAD The width of the SCR and the excess charge closely match calibrated TCAD. October 6, 2016 Slide 24

25 Parameter Extraction/Fitting Procedure Multi-objective genetic algorithm to automate parameter extraction Optimizer The optimizer varies the model parameters until the F.O.M. confirms that simulation matches data. - Measurement - Simulation October 6, 2016 Slide 25

26 Parameter Extraction Procedure Multi-objective genetic algorithm to automate parameter extraction IGBT-DIE 5SMY 12K1721, Ic = 100 A, Multiobjective optimization: 5 targets, 14 parameters Gate charge Turn-on Ic Good agreement with the remaining characteristics The model scales well with the load current Turn off Vce transfer On-state October 6, 2016 Slide 26

27 Results: System EMI/EMC simulations Low Voltage AC Drive Noise Simulations incl. cable models Line impedance stabilization network can be simulated in half time and without convergence issues on a circuit with variables. October 6, 2016 Slide 27

28 Conclusions 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 October 6, 2016 Slide 28

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