Presentation - Fluxgate Sensor Analysis

Transcript

Fluxgate Sensor Analysis Dennis Steward EM Application Engineer Ansoft Corporation Pittsburgh, PA Flux Gate Sensor Basics Z Simple Construction Z Drive Coil Z Core Z Easily Saturable Core Drive Coil Variable Inductance Z Z Function of Drive Current Function of External Magnetic Field Flux Gate Sensor Basics Typical B-H Curve 2 Saturated Saturated Region Region Linear Region 1.5 Saturated Region 1 B (T) 0.5 0 -8.0E+05 -6.0E+05 -4.0E+05 -2.0E+05 0.0E+00 2.0E+05 4.0E+05 6.0E+05 -0.5 Low Inductance -1 High Inductance -1.5 -2 H (A/m) Low Inductance Arrows Indicate Magnetizatio n Direction Sensor is Driven Between Linear and Saturated Regions of the B-H Curve 8.0E+05 Flux Gate Sensor Applications Z Z Typical Flux Gate Sensor Applications include: Z Proximity Sensing Z Magnetic Field Measurement (Navigation, Geomagnetics) Z Speed & Position Sensing Sensor has Linear Response Characteristic Arrows Indicate Magnetizatio n Direction Maxwell Setup How do I model a Flux Gate Sensor Using Maxwell? Maxwell 3D Optimetrics SIMPLORER Z Electromagentic Component Analysis Z Parametric Study of Component Z Model Extraction Z Initial Verification of Component Z Full System Simulation using Component Parametric Analysis Linear Region Saturated Region Z Curve Shifts Due To Influence of External Field Export Component Model Z Model Type Z Coil Parameters Z Extra Port (Bz) Component Analysis Fluxgate_Sensor_1 R1 oi_p E1 oi_m External Field Source Bz Z E2 EMF := 0 Waveform Distortion Caused by traversing the B-H Curve Sensor Current Response to a 2.5V, 100kHz Sinusoid 20.00m Z Current (A) 10.00m 0 -10.00m -20.00m 80.00u 85.00u 90.00u Time (s) 95.00u 100.00u Positive and Negative Areas are Equal Component Analysis Z External Field Shifts Curve Positively or Negatively Z Positive and Negative Areas are No Longer Equal Sensor Current Response to a 2.5V, 100kHz Sinusoid w/ External Field 25.0m 20.0m Current (A) 15.0m 10.0m 5.0m 0 -5.0m -10.0m -15.0m -20.0m -25.0m 8.00e-005 8.20e-005 8.40e-005 Force = 3.72N 8.60e-005 8.80e-005 Time (s) 9.00e-005 9.20e-005 9.40e-005 9.60e-005 Component Analysis Sensor Current Response to a 1.5V, 100kHz Sq. Wave w/ External Field 15.0m 12.5m 10.0m Current (A) 7.5m 5.0m 2.5m 0 -2.5m -5.0m -7.5m -10.0m -12.5m -15.0m 1.80e-004 1.83e-004 1.85e-004 1.88e-004 1.90e-004 1.93e-004 1.95e-004 1.98e-004 2.00e-004 Time (s) Z Sensor Behaves Similarly When Excited With a Square Wave Component Drive Signal Three State Drive Z 5V Z Ground 6.00 Z Float 5.00 Flux Gate Sensor Drive Voltage 5V Voltage (V) Z 5V 2.50 Float 0 0 GND Float Float GND 2.50e-006 5.00e-006 7.50e-006 1.00e-005 1.25e-005 1.50e-005 Time (s) Float 2.00e-005 Component Drive Circuit Z Drive Circuit Implementation Z 2 MOSFETS Are Fired alternately to create the 3 States for the Flux Gate Sensor TRAPEZ1 Fluxgate_Sensor_1 oi_m oi_p Bz GZ1 Delay EMSS - LINK System Analysis TRAPEZ1 Fluxgate_Sensor_1 Sensor Drive External Field Source oi_m oi_p Bz GZ1 Delay AM1 + A Component Model used in sensing circuit Low Pass Filter Integrator + + - - NSC_LM_741_2 NSC_LM_741_1 Translated SPICE Models Output + V System Analysis Z System Output Voltage is Proportional To Magnitude of External Field Flux Gate Sensor System Output Voltage 2.50 2.49 Voltage (V) 2.48 2.47 2.46 2.45 2.44 2.43 2.42 2.41 2.40 3.00e-003 3.50e-003 Time (s) 3.80e-003 System Analysis Final Differential Flux Gate Sensor Circuit Model Fluxgate_Sensor_1 External Field Source 1 oi_m oi_p MOS1 Sensor Drive 5V Bz E2 Float_1 1k Fluxgate_Sensor_2 MOS2 Float_2 Ground External Field Source 2 oi_m oi_p Bz E9 AM1 A + Low Pass Filter 220n 2k Integrator 1n 10n 2.5 + 1k 665 + - 10k NSC_LM_7411 - 68n NSC_LM_7412 2.5 Z State Machines Used to Fire MOSFETS Output + V VM1 System Analysis Z Differential Sensor Response Z External Field For Sensor 2 Changes from 0G to –2G at 2ms Z Output Voltage Shifts Downward to Reflect the Change Differential Flux Gate Sensor System Output Voltage 2.50 2.49 2.48 2.47 2.46 2.45 2.44 2.43 2.42 2.41 2.40 1.00e-003 2.00e-003 3.00e-003 4.00e-003 Conclusions Z Using Maxwell 3D and Optimetrics, the electromagnetic behavior of a Flux Gate Sensor may be accurately analyzed. Z A component model may be extracted from the Finite Element Analysis which may then be used to examine the impact of the component within a larger system. Z SIMPLORER provides an environment where the finite element component model may be combined with circuit, block diagram, and state machine elements to study the role of the component in a complete system.