The session describes how contactless magnetic position sensors are optimized for use in high-speed brushless DC (BLDC) motors to meet reliability/efficiency requirements. Attendees will learn: • Major advantages of BLDC motors including higher efficiency, low noise, longer life, and higher reliability • Key position sensing parameters and their relevance in the applications • How contact-less magnetic position sensors are optimized for use in BLDC motor apps • BLDC motor applications and key requirements in automotive and automation industries

1. Confidential © ams AG 2014
Efficient Motor Commutation through Advanced Position Sensing: The Trend towards Brushless DC Motors
Heinz Oyrer, Senior Manager Global Marketing
Sensors Expo and Conference , June 24-26, 2014

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EFFICIENT MOTOR COMMUTATION THROUGH ADVANCED POSITION SENSING
The Trend towards Brushless DC Motors
EFFICIENCY OF ELECTRICAL MOTORS
BRUSHLESS DC MOTORS
MOTOR POSITION SENSOR
INTEGRATED POSITION SENSING IN EPS

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•Electric motors are the single biggest consumer of electricity.
•They account for about 2/3 of industrial power consumption and, about 45% of global power consumption, according to a new analysis by the International Energy Agency
Source: CleanTechnica, abb.com/energyefficiency
Electric Motors Use Majority of Global Electricity

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•Thousands of words and column inches are devoted to topics such as nuclear power, renewable energy, and electric vehicles
•Rarely discussed is the fact that the majority of electric motors are inefficient, oversized, or running when they don’t need to be running.
Source: CleanTechnica, abb.com/energyefficiency
Majority of Electric Motors are Inefficient

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Opportunities for Efficiency
•Addressing the efficiency of electric motors is an important topic that needs to be tackled.
Source: CleanTechnica, abb.com/energyefficiency

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An electric motor system comprises three layers of equipment :
1.Electric motor: a fully functioning electric motor runs from the electric grid.
2.Core motor system. The core motor system controls torque and speed. It consists of the electric motor, its driven piece of mechanical equipment along with the necessary interconnection and a variable‐speed drive (VSD) system between the grid and the motor.
3.The total motor system consists of the core motor system plus the eventual application of power and the electric equipment between the grid and the motor.
Energy‐efficiency for Electric Motor‐driven Systems
Source: International Energy Agency,
Energy-Efficiency Policy Opportunities for Electric Motor-Driven Systems 2011

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EFFICIENT MOTOR COMMUTATION THROUGH ADVANCED POSITION SENSING
The Trend towards Brushless DC Motors
EFFICIENCY OF ELECTRICAL MOTORS
BRUSHLESS DC MOTORS
MOTOR POSITION SENSOR
INTEGRATED POSITION SENSING IN EPS

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Motor Types Key Parameters
Stepper Motor
AC Induction
Brushless / Servo
Universal

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•Brushless Direct Current (BLDC) motors are rapidly gaining popularity.
•BLDC motors are used in appliance, automotive, aerospace, consumer, medical, industrial automation equipment and instrumentation applications.
•BLDC motors do not use brushes for commutation; instead, they are electronically commutated.
•BLDC motors offer many advantages over brushed DC motors and induction motors, including:
Being more reliable: no brushes
Better speed versus torque characteristics
High dynamic response
High efficiency
Long operating life
Noiseless operation
Higher speed ranges, acceleration rates and torque/size ratio
Better EMC performance
•In addition, the ratio of torque delivered to the size of the motor is higher, making ideally suited for applications where space and weight are critical.
Introduction to Brushless DC Motors

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Brushless Direct Current (BLDC) motors are rapidly gaining popularity
•"Sales volumes of brushless DC motors are forecast to grow much faster than that of either brushed DC motors or stepper motors. Major advantages of brushless DC motors include higher efficiency at converting electricity into mechanical power, reduced noise, longer lifetime and higher reliability.“, Michael Liu, IMS Research
•E-Motor market is growing 40% from 2012 to 2017
Government regulations worldwide
•Require the industry to implement new efficiency classes IE1, IE2, IE3, … (IE = International Efficiency to reduce CO2 (higher efficiency means better motor control)
Key requirements in Automotive market
•Reducing CO2-emissions by saving weight and reducing fuel consumption
•Improve passenger safety and anti-collision systems and electric stability program
•Improve passenger comfort to reduce noise and improve handling
The Trend Towards Brushless Motors

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•Today: Cost of brushed > Cost of BLDC but < Cost of BLDC + electronics
•Near future: Cost of brushed = Cost of BLDC + PCB
•Future: Cost of brushed > Cost of BLDC + electronics  all brushed motors will be replaced by BLDC
•Most brushed motors do not have electronics but all BLDC need it. (Cost of brushed – Cost of BLDC) = available amount for electronics, however also cost pressure for electronics
•Reduce the number of gearboxes by increasing the torque of the motor - no gearbox means lower motor speed – direct drive
Cost Pressure for Brushless Motors

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•BLDC motors consist of a rotating permanent magnet (rotor) and (min) 3 equally spaced fixed windings (stator).
•By controlling the currents in the stator, a magnetic field of arbitrary direction and magnitude can be produced.
•Torque is produced by the attraction and repulsion between the rotor and stator field
•In the case of a brushed DC motor, feedback is implemented using a mechanical commutator and brushes. In a BLDC motor, it is achieved using multiple feedback sensors.
•The most commonly used sensors are hall sensors and optical encoders.
Brushless Motor Basics

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In order to apply the most efficient stator field, the position of the rotor must be known. There are several methods to detect the rotor position:
•Sensor-less
By measuring back-EMF and/or stator coil currents
•Optical switches
Using a coded disc
•Resolvers
Flanged onto the rotor shaft
•Hall switches
Embedded into the stator, actuated by the rotor magnet. Based on the combination of these three Hall sensor signals, the exact sequence of commutation can be determined.
•Integrated Hall sensors = Position Sensor
A Hall effect magnetic position sensor is a transducer that varies its output voltage in response to a magnetic field.
Mounted at the end of the shaft
Rotor Position Feedback

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Motor Application Requirements
Requirement
Sensor - Types
Sensorless
Speed control
•Magnetic Position Sensor
•Optical Encoder
Sensorless is possible with back EMF and FOC at speed > 300rpm*
Commutation
•3 discrete Hall switches
•Magnetic Position Sensor
•Optical Encoder
Sensorless is possible with back EMF and FOC at speed > 300rpm*
Position Control
Torque Control
•Optical Encoder
•Magnetic Position Sensor
•Inductive (Resolver)
Sensorless not possible Sensor always needed
EMF … electro magnetic force
FOC … field oriented control
* Lower rpm possible but very complex algorithms

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EFFICIENT MOTOR COMMUTATION THROUGH ADVANCED POSITION SENSING
The Trend towards Brushless DC Motors
EFFICIENCY OF ELECTRICAL MOTORS
BRUSHLESS DC MOTORS
MOTOR POSITION SENSOR
INTEGRATED POSITION SENSING IN EPS

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•One single Hall sensor can reduce component cost, the cost for precision mounting is saved
•It can output the rotor position by one single sensor and deliver the absolute angle position of the rotor during start
•Electric brake and hold
•Increase efficiency by software
•Applicable for small motor designs
•The sensor does not need to reside on specific positions inside the motor which results in more design freedom for the motor designer
•Power efficient (no power dissipation like with sensor-less/shunt)
•Easy integration
•High temperature environment
•High start-up torque, low torque ripple, low audible noise
•High accuracy, excellent reliability and high safety levels (automotive)
When Do Customers Need a Position Sensor?

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Efficient motor commutation
•Needs fast and accurate position measurement
Key enablers
•Measurement quantization (resolution)
•INL (integral-non-linearity)
•Noise
•System propagation delay
Benchmark
•INL (8mm Magnet + displacement) = 1.2deg
•Noise = 0.05deg
•System propagation delay = 1.9μs
•Core resolution = 14bit
•Maximum Speed = 28.000 rpm
•Flexible choice of interfaces
•Immunity to external stray field
Position Sensing for Efficient Motor Commutation

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Angle accuracy: ideal slope

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Angle accuracy: system propagation delay

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Integrated Dynamic Angle*) Error Compensation
Dynamic Angle Error
Hardware Compensation integrated!
No Software needed!
External HW + SW compensation needed
Magnetic Position Sensor System
*) DAEC™ - patent pending

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EFFICIENT MOTOR COMMUTATION THROUGH ADVANCED POSITION SENSING
The Trend towards Brushless DC Motors
EFFICIENCY OF ELECTRICAL MOTORS
BRUSHLESS DC MOTORS
MOTOR POSITION SENSOR
INTEGRATED POSITION SENSING IN EPS

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•Magnetic position sensing is now becoming the leading solution for automobile EPS systems that have greater operational effectiveness.
•Sophisticated sensor devices with multiple sensing elements on a single die enable faster and more accurate acquisition of information required by the EPS system.
•Precise position of the automobile's steering wheel, improved performance of its EPS system while keeping costs and required space to a minimum.
Stability over temperature
Robustness against tolerances
Robustness against interfering field
Up to 7 pole pairs
Up to 28.000 rpm (depending on application)
Angle error <1° deg
ISO26262-compliance (depending on OEM specification)
Integrated Position Sensing in EPS
BLDC
Rotor Position Sensor
Electric Power Steering dominates the steering market, EPS outperforms other markets in growth.
The motor position sensor controls the commutation of a brushless DC motor employed in the system.

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Summary
•Improving the efficiency of electric motors has become an important topic at a global level
•The core motor system offers a great potential for savings
Controlling torque and speed as well costs
BLDC motors as a key enabler
•BLDC motors offer many advantages over brushed DC motors and induction motors.
Better speed versus torque characteristics, high dynamic response, high efficiency, long operating life, noiseless operation, higher speed ranges, rugged construction and so on.
Torque delivered to the motor size is higher, making it ideal for applications where space and weight are critical factors.
BLDC motors find wide spread adoption in applications such as automotive, appliance, aerospace, consumer, medical, instrumentation and automation
•Magnetic position sensing as a monolithic integrated function is becoming the leading technology for motor control applications that demand:
Higher accuracy & broader speed specifications
Integrated chip design (no SW/HW compensation in ECU)
Reduced system & component costs
More design freedom for motor designers

24. Confidential © ams AG 2014
Thank you
Please contact me at heinz.oyrer@ams.com and/or visit our website www.ams.com

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APPENDIX

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1.) Higher efficiency (government – rules) … to reduce the CO2 ww
Motor market trends

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When Do Customers Need a Position Sensor?
Motor-Types
Benefits for the customer
Resolution [PPR]
Stepper Motor
- Count the steps and monitor the position - Reduce power consumption - Reduce motor size - Reduce total weight - Reduce system costs - Safety
200, 256 (10-bit) 300 400 500, 512 (11-bit)
BLDC Motor EC Motor
- Remove 3 discrete Hall switches (cost down) - Get also the absolute angle position of the rotor during start - Increase efficiency by software - Small motor designs possible
90 (8.5-bit) 360 (10.5-bit) 720 (11.5-bit)
PMSM Motor AC Servomotor
- Reduce system cost - Replace Optical Encoders - expensive (~15 – 50.- EUR) - Replace Resolvers - very expansive (> 50.- EUR) - Higher reliability compare to optical - Smaller motor design possible
500, 512 (11-bit) 1000, 1024 (12-bit) 2000 (13-bit) 2500 (~14-bit)
BLDC … Brushless DC Motor EC … Electric commutated PMSM … Permanent Magnet Synchron Motor

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Standard Interfaces
Interface name
Output for what?
Number of wires
Function
ABI (quadrature interface)
Incremental
3
- Speed & direction control - Position control
- Standardized - For high speed (up to 30.000 rpm)
UVW
Motor commutation
3
- Motor control (provide same output as 3 discrete Halls)
- Standardized on BLDC
PWM (pulse width modulation)
Absolute angle information
1
- Absolute rotor position information for start
- One wire only - Slow interface
SPI, I2C, SSI (digital interfaces)
Absolute angle information
2, 3, 4
- Absolute rotor position for start - Speed & direction control - Position control - Direct motor control
- Good for System Integrator - No standard for Motor Controller
Analog
Absolute angle information
1
Absolute rotor position information for start
- One wire only - Slow interface

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•Position sensors measure the distance a body has moved from its reference and the resulting output is given as a feedback to the control system.
•Motion of a body can be rectilinear or curvilinear; accordingly, position sensors are called linear position sensors or angular position sensors.
•Position sensors use different sensing principles to sense the displacement of a body. Depending on these different sensing principles they can be classified contacting or non-contacting position sensors.
•Contacting sensors measure linear or angular position through a mechanical connection whereas non-contacting position sensors measure the linear or angular position of an object without any physical contact.
What are position sensors?

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•Non-contacting position sensors are highly reliable and offer a long functional life due to the absence of mechanical parts and physical contact.
•Magnetic sensors use:
The Hall effect to determine position, angle, or displacement
The anisotropic magneto resistive effect or a magnetically actuated reed switch to detect magnetic fields generated by a reference magnet.
•Hall Effect based Magnetic Position Sensors - A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for sensing proximity switching, positioning, speed detection and current.
What are position sensors?

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•Emergence of contactless and integrated magnetic position sensors
•Traditional sensors are replaced by contactless sensors that handle complex and highly integrated electronics – delivering higher sensitivity, smaller form factors and increased flexibility
•Strong trend is going from simple angle and distance sensors towards robust, intelligent sensor systems and applications with multiple simultaneous measurement axes
•Tackling the shortcomings of optical, magneto resistive, inductive and linear Hall sensors and switches
•No wear, insensitive to humidity, dust, dirt and harsh environments
•Solutions offer enhanced precision, repeatability, and robustness in addition to stray field immunity.
Why hall-based magnetic position sensing?