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VHDL-AMS modelization of an alternator vehicle power system for stability studies

VHDL-AMS modelization of an alternator vehicle power system for stability studies. Pierre Tisserand Pierre Chassard Jean-François Bisson Philippe Hazard. Automobile Club de France The Integrated Electrical Solutions Forum Paris 27 May 2008. Agenda. Energy Management in Vehicle

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VHDL-AMS modelization of an alternator vehicle power system for stability studies

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  1. VHDL-AMS modelization of analternator vehicle power system for stability studies Pierre Tisserand Pierre Chassard Jean-François Bisson Philippe Hazard Automobile Club de France The Integrated Electrical Solutions Forum Paris 27 May 2008

  2. Agenda • Energy Management in Vehicle • Electrical Power Car System • System Overview • Alternator stability study in vehicle environment • Models • Stability • Simulation and Measurements • Conclusion

  3. Energy Management in Vehicle

  4. Electrical Power Car System (1) Starters Alternators Stop-Start Systems Retarders Remanufacturing for Aftermarket

  5. Electrical Power Car System (2) Alternator Machine Loads ASIC Battery Alternators Rectifying Bridge Mechanical Domain Electrical / Thermal Domain

  6. Energy management in vehicle: system overview Pulley Car Engine Alternator machine + Rectifying bridge diode Electrical Power delivery Regulator + Electrical loads battery Feedback measurement - Vehicle environment Electrical Power Generator • Alternator role: • Battery charging ￫ cranking energy for starter • 14.3V regulated voltage ￫ embedded electronic supply • Close loop system: • Alternator loads: battery and electrical network • An instability causes supply voltage fluctuation: • Bad battery charging ￫ Time life reduced drastically • Glittering of lamps, …

  7. Alternator Stability Study in Vehicle EnvironmentModels

  8. Alternator Model Based Measurements Pulley Output Current Current Rotor Alternator Pulley Output Current Alternator 1) Characterization of I alternator versus speed rotation Output current I rotor = constant 120 Amps Alt. Speed 5000 Rpm 2) Characterization of alternator gain and phase Alt Speed = constant Gain 30 Frequency Phase Frequency 2 Hz Frequency injection -45° On first order the variables Ir and N are considered independant

  9. Build a predictive battery and harness model Power cable Gain [dB] Frequency [Hz] (log scale) + Battery - Phase [degree] 10 Hz Frequency [Hz] (log scale) -10° Resistor + Capacitor Internal resistor Resistor - • Characterization of quadripole gain and phase • 2) Schematic and values of components fitted with the measures above Battery AC model

  10. Regulator model Phase dB 75Hz f 10dB 14V Clock To the rotor + Power stage Setting point PWM Modulator Direct Filter GAIN K - Feedback measurement Feedback Filter dB 762Hz

  11. System based VHDL-AMS for simulation

  12. Alternator Stability Study in Vehicle EnvironmentStability

  13. Stability Criteria • Open loop: the stability criteria usually applied are deducted from the (A(f)*B(f)) AC simulation • Phase Margin (PM) > 45° @ gain = 0dB • Gain Margin (GM) > 10dB @ phase = 180° • Close loop: criteria effects

  14. Black Chart Gain (dB) -180° -90° Ex: FT= K/(1 + T1P)(1+T2P) K PhaseMargin Gain -90° Phase (°) -90° Gain Margin -135° -10dB

  15. Simulation and Measurements

  16. Transient simulations The regulator parameters not adapted for the system ￫ voltage battery oscillation appears The regulator parameters adjusted￫ voltage battery oscillation disappears

  17. Stability comparison measurement simulation Simulation results Transferometer measurement results • Main results: • PM -> 60° • GM -> 20dB

  18. Conclusion

  19. Optimization of the parameters Customer requests (Imax, ripple voltage, loads, pulsed loads …) Alternator machine library (VHDL-AMS models) Parameters of the loop (gain, cut-off frequency, sampling frequency…) Virtual platform (ASIC regulator + Alternator machine + customer environment) Engineering sample validation

  20. Virtual platform perspectives • VHDL-AMS modelization of analternator vehicle power system • Easy building of complex multi-domain models • Optimization of parameters and shorten reactivity • Measurements / Simulations correlation • VHDL-AMS executable specifications • Specification refinement • Prediction and design cycle reduction • Pre-validation by specification simulations • Dynamic or transient specifications • SPICE / VHDL-AMS on the same simulation platform • Communication “vehicle” between supplier and customer • Capitalization of knowledge

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