Angular Position Sensing using
Inductive Sensing
Inductance-to-digital converters (LDC) from Texas Instruments
ti.com/ldc
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LDC for Angular Position Sensing
PCB Sensor
Coil
Benefits of
Inductive Sensing
Conductive
target shape
High-resolution applications:
• Steering angle
• Brake pedal
• Throttle position
• Transmission
• Torque sensing
• Etc.
Low-resolution applications:
• Knobs for white goods,
consumer and human
interface systems
Advantages of Inductive Sensing:
 Does not require magnets
 Reliable by virtue of being contactless
 Insensitive to environmental contaminants (dust, dirt, etc.)
 Sub-micron resolution
 Sensor is low-cost
 Electronics can be located remotely from the sensor
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Rotational Sensing
CONDUCTIVE
TARGET
CONDUCTIVE
TARGET
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OUTPUT3
OUTPUT1
OUTPUT2
LDC for Angular Position Sensing
Example: BLDC Motor Encoder demo design
The LDC1000 can sense the absolute
position and direction of the motor’s
rotor by measuring the unique
inductance waveform generated by a
rotating conductive target.
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Demo Hardware
TI Rotational Demo
featuring TI LDC1000
TBD
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Avnet ZedBoard
featuring Xilinx Zynq 7020
Avnet FMC Motor
Control Module
featuring TI signal chain
AES-Z7EV-7Z020-G
AES-FMC-MC1-G
13 unique TI devices
Supplier
Part #
TI
LDC1000
TI
ADS1204
TI
DRV8312
TI
TPS61240
3.5MHz High Efficiency Step-up Converter
TI
TLV70025
LDO 200mA
TI
LMV324
Quad Rail-To-Rail O/P OpAmp
TI
SN74LVC1G14
Single Schemitt Trigger Inverter
TI
CAT24C02
I2C 2Kb Serial EEProm
TI
SN74AVCH16T245
16b Dual Supply Bus Transceiver
THS4524
Ver Low Power, Negative Rail Input, Rail-ToRail O/P Full Differental Amp
LP339
Quad Differential Comparators
SN74CB3T3245
8-Bit FET 2.5-V/3.3-V Low-Voltage Bus Switch
With 5-V Tolerant Level Shifter
SN74LVCH8T245
8b Dual Supply Bus Transceiver
TI
TI
TI
TI
TI Information – Selective Disclosure
Desc.
Inductive Sensing
Quad 1-Bit 10MHz 2nd Order Delta-Sigma
Modulators
Three Phase PWM Motor Driver
6
What does it show?
• A new way to implement motor encoding
• LDC1000 senses the absolute position of the motor’s rotor by
measuring the unique inductance waveform generated by a rotating
conductive target
• The 3-phase brushless DC motor is driven by a velocity controller using
a Xilinx Zynq®-7000 AP SoC on the ZedBoard platform
TI Information – Selective Disclosure
Demo Setup Instructions
• Follow steps 1-5 below to setup and start the demo
(2) Connect Motor
to FMC
(1) Connect 12V
supply
(3) Connect Hall
Sensors to FMC
(4) Turn ON
(5) Press to start motor
[up/down buttons control speed]
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Demo System Diagram
TI Information – Selective Disclosure
What is the demo rollout plan?
• Phase 1 (now)
– TI LDC1000 hardware design for absolute angular measurement
– Xilinx Zynq 7020 velocity controller
– TI signal chain driving a 3-phase BLDC motor via Avnet’s FMC-MC1 module
• Phase 2 (coming soon)
– Xilinx Zynq 7020 uses LDC1000 measurements to estimate velocity
– Report velocity using ZedBoard OLED display
• Phase 3 (future)
– Add Field Oriented Controller (FOC) for torque control
– Waveform capture
Gauging customer interest for a similar development kit
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Exhibit Collateral
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APPENDIX
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Avnet’s Motor Control FMC Module
Featuring TI Analog Signal Chain (inc. DRV8312 and ADS1204)
• AES-FMC-MC1-G
$499 USD
– Includes BLDC and Stepper
• AES-FMC-MC1-LT-G
– No motors
TI Information – Selective Disclosure
$349 USD