HALL EFFECT MAGNETIC SENSOR FOR AUTOMOTIVE APPLICATION

Transcription

1 HALL EFFECT MAGNETC SENSOR FOR AUTOMOTVE APPLCATON Samir GUERBAOU R&D Engineering 16/10/2013

2 Summary : Part 1 Reminder on the position measurement 1 Hall Effect sensor Part 2 Permanent magnets Mathematic method for measurement... Product studies presentation 5 minutes 13 minutes Magnetic position sensors for EGR systems. Magnetic position sensors for E-Valve actuators... Magnetic position sensors for transmission. Part 3 Prediction accuracy status 6 7 Valeo status on Flux3D simulations use. 2 minutes 2011/04/11 2 CONFDENTAL

3 Part 1 1 Reminder on the position measurement

4 1 Hall Effect sensor

5 Operation principle : The magnetic sensor used is a monolithic sensor C featuring the Triaxis Hall technology. The Triaxis Hall sensor is also sensitive to the flux density applied parallel l to the C surface.. This is obtained through an ntegrated Magneto- Concentrator which is deposited on the CMOS die (as an additional back-end step). The magnetic sensor used is sensitive to the 3 components of the flux density applied to the C (Bx, By and Bz). This allows the magnetic sensor used to sense any magnet moving in its surrounding and it enables the design of new generation of non-contacting joystick position sensors which are often required for both automotive and industrial applications. Melexis with Triaxis sensor is the main supplier for 3D/Joystick application hall effect sensor. CONFDENTAL

6 Physic understanding (1) : Hall effect inputs and outputs ts : An electrical conductor active element converses magnetic field in an electrical stress (Hall effect phenomenon). élément Active actif element Current in the element Magnetic induction Hall electric tension Élément actif Filtrage Préamplification Suiveur Miroir de courant An electronic treatment allows to condition the output signal to create a linearization of the response. The main action to lead for the sensor design is to associate it with a controlled magnetic source. 18/02/ CONFDENTAL

7 Physic understanding (2) : Hall effect operation : A magnetic source permits to disturb the hall effect sensor active element on a specific area. The following picture presents as an example a linear magnetic position sensor (in red) using a NdFeB magnet as magnetic source. 400 µm air gap The Flux3D simulations enable to calculate the induction level read dby the Hall effect sensor. Permanent magnet, air gap and hall effect sensor create a position measurement system. 18/02/ CONFDENTAL

8 Hall effect sensor available : The hall effect suppliers Road map for 3D/Joystick application hall effect sensors is presented below : Hall effect supplier 2D sensor Sensor 2D type 3D sensor Melexis YES n production YES Sensor 3D type See following slide Micronas YES n development NO AMS YES n development YES AS5412 NXP YES AMR NO nfineon YES GMR NO Allegro YES Circular Certical Hall NO Melexis with Triaxis sensor is the main supplier for 3D/Joystick application hall effect sensors. 2011/04/11 8 CONFDENTAL

9 Melexis Hall effect sensor available : The Melexis Road map for 3D/Joystick application hall effect sensor is presented below : MLX90333 (Gen ) MLX90363 (Gen ) MLX90365 (Gen ) MLX90366 (Gen ½) MLX90366 (Gen ½) Leadframe MLX90367 (Gen ½) Calibration 16 points per signal same calibration for each signal Calibration 3 points per signal Calibration Specific Firmwafre 50 k Calibration 16 points per signal same calibration for each signal Calibration Via interface microcontroleur du SP Pin number 3 Pin number 4 Pin number 3 Pin number 3 Pin number 5 Specific Serial Protocol SENT Protocol Analog or PWM Protocol Protocol SENT Protocol SP PWM Time 2008 Q Q Q Currently no standard hall effect sensors allow us to have multipoint calibration for each signal with PWM protocol. 2011/04/11 9 CONFDENTAL

10 2 Permanent magnets

11 Physical characteristics: Main characteristics : To choose a magnet, a compromise is searched between the packaging (air gap available), the induction tolerated by the Hall effect sensor electronic architecture and the demagnetization risk in the environment. The intrinsic induction-magnetic field applied characteristic of the magnet material associated with the air gap are sufficient to determine the magnetic functional point of the magnetic flux generator. All physical information are contained in the intrinsic inductionmagnetic field applied characteristic. 18/02/ CONFDENTAL

12 Magnetic functional point : Determination of the magnetic functional point : 30 mt 20 mt For a magnet alone, the magnetic functional point is due to multipolar magnetic fields (demagnetization field also called the magnetocrystal anisotropic interaction). To determine this point, it is possible to calculate it with an abacus or to measure the induction level with a Gaussmeter. 10 mt 19,12 mm 0mT 9,54 mm -10 mt -20 mt -30 mt 15 mm 20 mm 25 mm 30 mm 35 mm 40 mm 45 mm 50 mm 55 mm 60 mm 65 mm 70 mm 75 mm 80 mm 85 mm 0,45 T Weiss domain in the magnet Thermodynamic balance for each domain The magnetic functional point allows to determine the real intrinsic induction level create by the magnet and due to the thermodynamic equilibrium of the Weiss magnetic domain. 18/02/ CONFDENTAL

13 Permanent magnets multi-performances : The choice of a magnet is a compromise : The choice for the magnetic source is a compromise between the induction level, the coercivity field and others physical characteristics. The Hall effect sensor and the magnet have to be designed together to ensure the coherence between Hall sensor input needs and magnet performances. The magnetic sensor performances depend on the magnet characteristics. 18/02/ CONFDENTAL

14 3 Mathematic ti method for measurement

15 Operation principle (1) : Mathematic operations : By Bz Bx The magnetic induction created by a magnet with an axial magnetization in the 3 dimensions present a cosinusoidal behavior for the axial direction and a sinusoidal behavior for the radial direction. Co omponent indu uction (G) Evolution of magnetic field during translation Shifter shaft translation (degree) Atan ( degr ré) 160,00 120,00 80,00 40,00 0, Position (mm) The arctangent calculation associated to these signals allows to obtain a nearly linear signal The magnetic sensor performances depend on the phase shift between the different induction magnetic components. 2011/04/11 15 CONFDENTAL

16 Operation principle (2) The magnet is moving Measurement of the 3 Arctangent t calculation l and and the sensor is fixed components of the magnetic field linearization The rotation and/or translation creates a variation of the magnetic flux all around the magnet LATON X TRANS nt induction (G) Compone By Bz Evolution of magnetic field during translation Bx t signal X X sensor res sponse (arctg value) Output Before calibration After calibration SPEED AR SPEED 1 and 2 SPEED 3 and 4 SPEED 5 and Shifter shaft translation (degree) X position (mm) Shifter shaft translation ti (mm) 600 By Bz Bx Before calibration After calibration ROTATON (G) Co omponent induction Evolution of magnetic field during rotation Theta sensor response (arctg value) Output signal SPEED AR, 1 ou 5 Neutral point SPEED 2, 4 ou Shifter shaft rotation (degree) Angle Theta ( ) Shifter shaft rotation (degree) The sensor measures X and θ positions. 2011/04/11 16 CONFDENTAL

17 Part 2 1 Product studies presentation

18 4 Magnetic position sensors for EGR systems

19 Fuel combustion : -During combustion with high percent of oxygen, the thermal range is very high (> 1200 C) - this level of temperature allows chemical reactions between molecules in the combustion chamber - Some of the new chemical molecules are considered as pollution The combustion at high temperature creates new chemical molecules. 2011/04/11 19 CONFDENTAL

20 Diesel EGR Valve presentation : The EGR valve allows to reduce NOx emission if the close loop is ensured. 2011/04/11 20 CONFDENTAL

21 Drivability and position sensor (1) : Sensor position localization EGR Valve with DC motor t s the same operation principle p for the bypass components and the same Hall effect magnetic sensor. The current Valeo EGR valves are electrically piloted, the position valve is realized by a DC motors and the close loop control is ensured by an angular Hall effect magnetic sensor. All EGR valves and Throttles use the same Hall effect magnetic sensor for close loop control. 2011/04/11 21 CONFDENTAL

22 Drivability and position sensor (2) : To ensure the drivability of EGR valve, a permanent measurement has to be realized. Hall effect sensor The drivability requires an angular position sensor. Permanent magnet in rotation with the DC motors activation The Hall effect magnetic position sensor ensures the EGR valve close loop control. 2011/04/11 22 CONFDENTAL

23 Hall effect magnetic position sensor simulations: Simulation for a ferrite magnet in rotation 600 By Bz Bx 500 Component in nduction (G) Evolution of magnetic field during rotation Magnet rotation (degree) Mag gnetic induction (mt) Flux3D simulations Gaussmeter measurements Ferrite magnet 10x12x6 upper sensor limit upper sensor limit for Ferrite lower sensor limit for Ferrite lower sensor limit The rotation is simulated by taking the intensity of each induction components for different positions around the magnet (simulated in magnetostatic). The correlation was made with a variation of the air gap between magnet and the hall effect sensor. Currently, for the ferrite magnet, the simulation prediction accuracy is evaluated at +/- 5 mt in the air gap air gap (mm) The Flux3D simulations accuracy prediction ensures the performance calculations relevance. 2011/04/11 23 CONFDENTAL

24 5 Magnetic position sensors for E-Valve actuators

25 E-valve micrometric magnetic sensor non linearity: NdFeB permanent 1T Diamètre extérieur : 7.5 mm Déflexion angulaire de 50 Flux3D simulations enable to evaluate the flux variation function of shaft position. Diamètreintérieur intérieur : 5,5 55mm Aimantation radiale d amplitude 700 mt Hauteur: 10 mm E-valve actuator with shaft translation from 0 to 8 mm. The simulated non linearity of the magnetic sensor is evaluated with an accuracy prediction of +/-5%. 2011/04/11 25 CONFDENTAL

26 E-valve micrometer magnetic sensor optimization: Flux3D simulations are used in the DOE response surfaces studies to design and optimize the products. E-valve actuator with shaft translation of 0 to 8 mm. Flux3D simulations allow optimization without the use of costly prototypes. 2011/04/11 26 CONFDENTAL

27 6 Magnetic position sensors for transmission

28 Magnetic sensors for position measurements: No view Confidential No view Confidential No view Confidential Lots of sensors used in transmission are based on the Hall effect sensor technology. 2011/04/11 28 CONFDENTAL

29 X-Theta sensors position measurements: For example, the X-Theta sensor is perfect to show all the possibilities existing for measurements in the 3-dimensions Steel axis X X Z θ Y 600 By Bz Bx 500 Flux3D simulations NdFeB magnet Calculation area ction (G) Component indu Evolution of magnetic field during rotation Magnet rotation (degree) All rotations and/or translations can be measured by the X-Theta sensor 2011/04/11 29 CONFDENTAL

30 X-Theta sensors simulations: Flux3D simulations indicate the magnetic components variation with rotations and/or translations The induction components variation analysis allow to design the magnetic sensor. 2011/04/11 30 CONFDENTAL

31 X-Theta sensors correlations: nduction magnetic components Simulations Measurements duction (mt) nd Position X( (mm) After the discrimination of all influent factors associated to the difference between simulations and measurements, correlations show an accuracy prediction of +/-15% The arctangent operation allows to reduce this value and, after realizing induction components ratio, the value decreases to +/-5% The Flux3D simulations accuracy prediction is increased by the arctangent operation. 2011/04/11 31 CONFDENTAL

32 Clutch position magnetic sensors : Clutch actuator system Measurements 30 mt Simulations 20 mt 10 mt The sensor conception Th ti and d optimization are realized with the association of Flux3D simulations and Design Expert DOE. 0 mt -20 mt -30 mt 15 mm 20 mm 25 mm 30 mm 35 mm 40 mm 45 mm 50 mm 55 mm 60 mm 65 mm 70 mm 75 mm 80 mm (m ur ue ng Lo m ) The correlation shows that the AlNiCo magnet, this due to its low anisotropic configuration, does not allows to have a good accuracy prediction with simulations (in comparison with the Rare Earth magnets). 85 mm Pe nte magnéti P m) que (mt/mm -10 mt ) (mm è tre Diam For AlNiCo magnet the accuracy prediction is +/- 40%. 2011/04/11 32 CONFDENTAL

33 7 Valeo status on Flux3D simulations use

34 Valeo status on Flux3D simulations use : The accuracy prediction errors are mainly due to : - the bad material intrinsic properties knowledge - the fact of not taking into account of all physical phenomena in simulations - limited numerical performances (very poor mesh density in residual air gap) Prediction accuracy Product Relevant factors Response (due to correlation with measurements) AlNiCo Magnetic position sensors Ferrite Magnetic position sensors Rare Earth Magnetic position sensors Air gap Magentization intensity Magnet volume Air gap Magentization intensity Magnet volume Air gap Magentization intensity Magnet volume nduction (mt) +/ 40% nduction (mt) +/ 15% nduction (mt) +/ 5% Valeo studies have shown that simulations need a good material intrinsic properties knowledge and a good physical phenomena knowledge in order to limit errors on accuracy prediction. 2011/04/11 34 CONFDENTAL

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