Optimized Motor Control Solutions

www.zilog.com

Zilog Motor Control Technologies• Optimized motor control strategies and solutions
relevant to today's industry requirements• Embedded software to leverage motor control
capabilities• Custom code development
Demands on the efficiency and control of electric motors isincreasing across every commercial sector, from white goods
and electric vehicles to industrial installations and aerospace
applications. ACIM machines have supported most commercial
requirements for decades, but the ability to control them hasoften been very limited due to their typical operation via
mains-supplied frequencies.
With the advent of affordable microcontrollers, control of
ACIM motors has greatly increased because the mains voltage
can be rectified and stepped down so that a microcontroller canbe used to generate a sine wave pattern and control signals to
operate the ACIM machine. Nevertheless, there is a slip factor

intrinsic to ACIM machines known as asynchronous speed, afactor which makes an ACIM machine less efficient than its
brushless DC (BLDC) counterparts, especially at smaller motor
sizes. Meanwhile, permanent-magnet synchronous (PMSM)
and synchronous AC motors are typically more efficient, andare suitable for even the most demanding of applications.
To evaluate suitable driving methods for BLDC, PMSM, or
ACIM motors, Zilog has developed a comprehensive MultiMotor Series motor control kit featuring Zilog's Z32F128 ARM
Cortex M3, which facilitates operation across these motor types
with differing control schemes so that developers can choose
the driver scheme that is most suitable for their application.

Topics Discussed Inside
•
•
•
•
•

Motor Control Strategies•

Characteristics and Applications:– Single-Phase BLDC Motors– Three-Phase BLDC Motors– Trapezoidal Hall Sensor vs.
Sensorless Commutation– Space Vector Modulation– Field Oriented Control– Stepper Motors•

The Z16FMC MCU and the Z32F128
ARM Cortex M3 MCU••

The MultiMotor Series Development Kit

Control Strategy by Motor Type
Open- vs. Closed-Loop Speed Control
Regenerative Braking Control
Projected Market Share for Electric
MotorsZilog Motor Control Development Tools

Zilog's MultiMotor Series Motor Control Development Kit

May 2016

PB025504-0516

Zilog-Supported Motor Control Strategies
The Difference Between Asynchronous and Synchronous
Machines
Permanent Magnet Synchronous Motors (PMSM, PMAC) andbrushless DC motors (BLDC) are synchronous machines
because they contain permanent magnets whose flux fields
interact immediately with the stator flux field to commutate
the rotor. Therefore PMSM machines are typically more efficient than ACIM, typically greater than 90% and less than100%.
AC Induction Motor Machines (ACIM) is an asynchronous electrodynamic machine with no permanent magnets. The current
induced flux field in the windings has to build up a flux field in
the air gap and iron of the rotor first before these two fields caninteract and produce the torque to commutate the shaft.
Therefore there is a lag between the iron flux and stator flux
fields, commonly termed slip. Due tothis slip, ACIM are less efficient, typically around 60 to 80%. Induction
motor machines have an intrinsicallypoor transient performance between
steady states but field-oriented control(FOC) motors address this issue.
Motor Control Methodologies
These motor control parameters can bemonitored with the following control
driving schemes, all of which Zilog supports with corresponding application
notes:• Sensorless 3-phase trapezoidal
commutation• Hall sensor 3-phase trapezoidal
commutation• Sinusoidal PWM commutation
with Hall sensor feedback• Space vector modulation with Hall sensor feedback for
BLDC motors• Space vector modulation ACIM machine commutation
with the V/F principle• Single-shunt space vector control/FOC for ACIM using
rectangular coordinates• Dual shunt space vector control/FOC for ACIM using polar coordinates
Types of Electric Motors
Brush-type BLDC motors
Three-phase brushless BLDC motor (suitable for trapezoidal commutation)• Permanent Magnet Synchronous (PMSM, PMAC) machines with sinusoidal wound stator wire distribution(suitable for sinusoidal-, space vector-, and FOC-controlled commutation due to less cogging torque)• AC induction motor (ACIM): asynchronous machines
suitable for sinusoidal, space vector modulation, andfield-oriented control••

May 2016

Common Control Strategies
Block commutation adjusts the phase-angle every sixty
degrees, thereby introducing a ± 30 degree error; however, thisis acceptable for many motor drive applications. Sinusoidal
control (including space vector modulation and field-oriented
control) allows for adjustment of the commutation so that therotor and stator flux fields are at 90 degrees to each other.
Common commutation schemes include:• Single-phase trapezoidal commutation (Hall sensor)• Three-phase trapezoidal commutation (sensored/sensorless)• Sinusoidal PWM modulation (Hall, encoder)• Space vector modulation (predominantly for ACIM andPMSM machines mostly sensor using encoders or Halls)• Space vector control/FOC mostly used for ACIM but canbe designed for PMSM
Choice of Control Strategy by Motor
Type
Sinusoidal controls are suitable for
BLDC type motors because this driving
scheme utilizes more of the bus voltage
and tends to run the BLDC machine
more quietly, both electrically andaccoustically. However, the current
waveform may not be very sinusoidal
because BLDC type machines have nosinusoidal wound stators and therefore,a higher detent. On the other hand,using trapezoidal motor control on
PMSM or ACIM machines with sinusoidal wound stators does not utilize thebenefits of these types of machines
either.
Sinusoidal PWM, Field Oriented Control and Space Vector Modulation strategies are best suited for
ACIM, PMSM or PMAC type machines because they havesinusoidal wound stators utilizing the benefits of these control
strategies.
Open-Loop vs. Closed-Loop Speed Control• To some extent, electric motors have self-governing
closed-loop properties• Closed-loop speed control operation may not be suitable
for some types of applications• In the case of air-moving fans and blowers, the pressure
vs. flow characteristics are very different not only between radial and axial types of motors, but also underclosed-loop and open-loop speed control (i.e., stall points).
Depending on these cases, closed-loop control may or may
not be desired• Arguably, in the case of vehicular applications, closedloop speed control may not be suitable unless when operated in a cruise control mode

PB025504-0516

•

Closed-loop torque or speed (inner/outer control loops)
controls are suitable for power tool applications because
the torque will go up under higher load conditions

Regenerative Braking• Depending on which qudrant the motor operates, an electric motor is in either motoring or generating mode
• One of the advantages of electrodynamic machines is theability to produce regenerative voltages even without sophisticated inverter switching techniques•

Some motor control applications may require the motor
to reach terminal speed at a defined acceleration rate andtherefore require closed-loop operation•

In generating mode, the motor currents produce negative
torque, causing a plug braking effect, which may be required for some applications.
In conjunction with the motor inverter bridge and PWM
switching techniques, regenerative energy can be efficiently channeled for battery charging purposes•

Regenerative Braking Control

Type of Control/Motor
BLDC with blockcommutation

Motor Types Suitable For Regeneration And Motoring

Sinusoidal
Wound Stator(PMSM, PMAC
and ACIM)

Nonsinusoidal
Wound Stator(BLDC)

Yes, but not ideal

Ideal

Type of Control/Motor

BLDC with Sinusoidal
PWM

Ideal

Space Vector Modulation

Ideal

Yes, but not ideal

Space Vector Control
(FOC)

Ideal

Yes, but not ideal

Yes, but not ideal

Motoring

Regeneration

Single phase

Yes

Not ideal

Three-phase blockcommutation

Yes

Yes

Sinusoidal and SVM/FOC
using ACIM/PMSM

Yes

Ideally suited

Stepper motor(discrete steps)

Yes

No

Servo motor

Yes

Not ideal

MCU Resource Usage Comparison By Control Strategy
Type of Control

Performance

Cost

Code Complexity

Low

Low

Low

Telecommunications,commercial

Three-phase sensor

MediumMediumLow

Telecommunications,commercial, vehicularThree-phase sensorless

Medium

Low to Medium

Medium to highTelecommunications,commercial, white goods

Sinusoidal PWM

Medium to highMedium to highMedium to highWhite goods, industrial,commercial, vehicularSpace Vector Modulation

Medium to highMedium to highMedium to highWhite goods, industrial,commercial, vehicular

Field Oriented Control

High

High

High

Single phase

Market Share by Motor Type• AC Induction Motor type machines are projected to havethe largest product segment of the market by 2017
• BLDC/PMSM machines are predicted to have the second
highest market share by 2017

May 2016•

Applications

High performance, industrial,
vehicular

Among major markets, BLDC machines for heating andcooling equipment are projected to be the fastest growing
market sector

PB025504-0516

Single-Phase BLDC Motors
Single-phase BLDC motors consist of simple hardware andsoftware requirements because they only require an H-bridge
inverter to produce a single-phase voltage.
Single-phase BLDC
motors are typicallyused in cost-sensitive
applications, and areoften used to control
fan motors.
Single-phase designs
can yield undesired
effects and exhibit
low efficiencies in fan
applications – as little as 35 to 40% –and generally produce high ripple currents. Single-phase
BLDC fan motors are found in every aspect of the industry,
mainly when removing heat from electrical systems is arequirement.
Applications that employ Single-Phase BLDC Motors• Telecommunications, radial/axial fans for:– Servers

•
•
•

–
–
–

Fans
Fan trays
Blowers
Automotive climate adjustment
Water pumps
Single-stator wire-wound for trapezoidal back electromotive force (BEMF) generation

Advantages of Single-Phase Control• Simple H-bridge hardware design• Simple software implementation• Low resource demands on MCU• Low BOM cost
Disadvantages of Single-Phase Control• High electrical noise signature• High acoustical noise signature• High total harmonics• High ripple currents• Higher stress on ripple current electrolytic capacitors• Higher stress on ball bearings• Typically less efficient than three phase machines

Zilog Single-Phase Motor Control Offerings
ZNEO32!

Z8 Encore!

ZNEO

Z8051

S3

Z32F128

Z8F0130, Z8F0230
Z8F0231, Z8F0430, Z8F0830
Z8FMC04, Z8FMC08,
Z8FMC16

Z16FMC2
Z16FMC3
Z16FMC6Z51F0410, Z51F0811
Z51F3220, Z51F3230
Z51F6412

S3F80P5,S3F80P9
S3F8S15, S3F8S19
S3F8S35, S3F8S39
S3F8S45

Three-Phase BLDC Motors
Trapezoidal commutation is also referred to as block or six-step
commutation. Hall sensor feedback can provide binary information to commutate a 3-phasemotor every 1/6thof an electrical revolution. With sensorlesscommutation, theBEMF is detected
every 1/6th of anelectrical revolution to commutate
the motor.
The phase angle
synchronization insix-step commutation is rather
May 2016

approximate, because the optimum commutation step occurs
when the rotor is perpendicular to the stator field. However,this state cannot be achieved commonly with Hall or sensorlesscommutation; therefore, the phase angle is adjusted every
sixty degrees, which introduces an error of ± 30 degrees. Nevertheless, for most applications, this compromise is acceptable.
Applications that employ 3-Phase Trapezoidal
Commutation• Used in virtually every aspect in the industry• Heavy use in vehicles (e.g., air movement, seat adjustment)• Power tools• Industrial• Commercial
Advantages of Three-Phase Trapezoidal Motor Control• Less acoustical noise
PB025504-0516

•
•
•
•
•

Less electrical noise
Generally higher life expectancy of electrical and mechanical components compared to single-phase machines
Less cost if operated sensorless
Generally higher torque than single phase
Less cogging torque and ripple current than single phasemachines

Disadvantages of Three-Phase Trapezoidal Motor Control• Higher BOM cost if operated with Hall sensors• Higher complexity of software for sensorless commutation mode
• Hardware design complexity higher than single phase• Manufacturability• Commutation angles are adjusted every 60 degrees as opposed to the ideal 90 degree commutation switching.
Phase Voltages with respect to Hall Binary States
Zilog Three-Phase Motor Control Offerings
Z8 Encore!

ZNEO

Z8051

S3

Z8FMC04
Z8FMC08
Z8FMC16

Z16FMC2
Z16FMC3
Z16FMC6

Z51F3220
Z51F3230

Only with additional softwareand discrete components;
contact Zilog Sales

Trapezoidal Hall Sensor vs. Sensorless Commutation
To commutate a Hall sensor-operated BLDC machine, therotor magnets pass across Hall sensors to generate the binary
information required to commutate the rotor shaft. This information is available at power-up; therefore the motor is capableof running at very low speeds. Hall sensor-operated BLDC
machines are often used for high torque requirements. Though
not always the case with sensorless operation, Hall sensor information is always available and is independent of high load currents.
For smooth startup, a sensorless-commutated BLDC machinemust have a defined startup ramp until the speed is highenough to detect the BEMF information required to commutate the motor, according to the equation EMF = B*L*v. Thisequation states that the generated BEMF is contingent on theflux field strength, the length of the inductor, and the velocity
of motor rotation. Therefore, if the velocity of the rotor is low,sensorless machines may not be
ideal candidates for low-speed applications and may not be as suitablefor high-torque applications because
DC OUT
the generated BEMF information
AC IN
may become lost at high currents.
This loss can occur because stored
magnetic energy in the motor windings will discharge in the form of
inductive spikes every six commutation steps. Therefore, if the load current is high, the width of the

May 2016

inductive spike containing the stored energy of the windings
can be wide enough to delay the rising BEMF signal so that it
can no longer be detected.
Characteristics of Sinusoidal Current Control of PMSM/
ACIM Machines
To operate BLDC permanent-magnet synchronous and permanent-magnet AC machines, three 120-degree sinusoidal waveforms must be applied to the motor’s windings. The simplified
diagram below illustrates a conversion from AC to DC andback to the MCU-generated AC signals across the inverter
bridge.
Applications that employ Sinusoidal PWM Modulation• Automotive• White goods

AC OUT frominverter

Z16FMCMCU

PB025504-0516

•

Motion control (e.g., ceiling fans)

Advantages of Sinusoidal PWM Modulation
Ideal for ACIM/PMSM and BLDC machine types
All three phases are energized at any given time
Near-constant torque
Flux is sinusoidally distributed
Virtually no ripple current
Electrical and acoustical noise is significantly lower thanin block-commutated machines due to absence of steep
current transitions• Generally higher lifetime and efficiency of electrical andmechanical components compared to single- or 3-phase
block-commutated machines• Simple V/F scaling operations (Volts per Hertz profiler)• As with space vector modulation and field-oriented control, PWM sine modulations have 15% more bus voltage

•
•
•
•
•
•

utilization and efficiency if a third harmonic-injected sine
wave is implemented
Potential Disadvantages of Sinusoidal PWM Modulation• Higher software complexity• MCU cost potentially higher than block commutated machines due to higher resource demands• If no third harmonic injected then sine wave then less efficient when compared to Space Vector Modulated machines• Total linear switching power losses typically higher thanblock commutated machines, unless Space Vector Modulation is used, which allows 2/3rd phase switching.
• Torque and field producing components (d-q) are not controlled separately, meaning the orthogonal relationship ofthe d-q components can become distorted at high speeds,
partially due to effects of the BEMF and lagging effects of
the PI loops.

Zilog Sinusoidal PWM Motor Control Offerings
ZNEO32!

Z8 Encore!

ZNEO

Z32F128

Z8FMC04, Z8FMC08, Z8FMC16Z16FMC2, Z16FMC3, Z16FMC6Space Vector Modulation
Contrary to the PWM Sine Modulation strategy in which eachleg in the inverter generates each phase sine wave independently, SVM strategy treats the entire inverter as a single unit
to generate the rotating space vector, VREF, and the three 120
degree-shifted waveforms, as illustrated in the hexagon below.

The rotating space vector VREF rotates within this hexagon,
according to the following equation.
V MAGjθ
V REF = ------------------ . e
V NOM

Therefore the magnitude and the angular position of the rotor
must be known to determine which sector of the hexagon VREF
is to be generated by using the adjacent base vectors. The adjacent base vectors are then time-modulated together with thezero vectors V0 and V7 and scalar quantities r1 and r2 using
the following two equations.
V REF = r 1 . V 1 + r 2 . V 2
r1 =r2
Rotating Reference Vector VS within the Hexagon at Angle Theta

May 2016=

us
3 ----------- sin ( 60° – ∆θ )U dc
us
3 ----------- sin ( ∆θ )U dc

The T0, T1, and T2 space vector modulation periods arederived from r1 and r2 using the following three equations.

PB025504-0516

T 0 = ( 1 – r 1 – r 2) T
= r T
1
T = r T
2
2
T

1

Using the equations above, a space vector can be generated at
any angular position within the hexagon. V0 and V7 are calledzero vectors because they produce no voltage across the inverter
bridge. In the hexagon figure, the adjacent base vectors are V1
and V2, and the reference vector VREF is located at approximately 40 degrees in the counterclockwise direction. The magnitude VMAG determines the length of this reference voltage
vector VREF.
Space Vector Modulation Waveform
The following figure presents the typical Space Vector Modulation phase voltage and phase current on a PMSM machine.

Applications that employ Space Vector Modulation• Automotive• White goods (washing machines and dryers)• Small home appliances• Aerospace
Advantages of Space Vector Modulation• Higher life time of electrical components• Suitable for ACIM and PMSM or BLDC machine operation• The same hardware as used for Sinusoidal PMM modulation can be implemented for Space Vector Modulation• Multiple Space Vector Modulation switching strategies
can be applied to:– Reduce linear switching power losses– Reduce total harmonics– Combination of switching strategies••

Higher bus voltage utilization than non-third harmonic
injected PWM sine modulation since center voltages canfloat around VDD/2
Simple V/F scaling operations (Volt per Hertz) where applicable

Disadvantages of Space Vector Modulation• Higher code complexity• Higher MCU cost due to resource demands• As with sinusoidal PWM, torque and field producing components (d-q) are not controlled separately, meaning thatthe orthogonal relationship of the d-q components can become distorted at high speeds due to BEMF and PI loop
lag effects.

Field Oriented Control
Field-oriented vector control (FOC) controls the d-q components of a brushless motor to mimic the d-q control characteristics of a brushed DC
machine in which
the orthogonal relationship between
flux and torque isalways maintainedby the motor’s contacts and brushes.
These d-q currents
exist naturally in an
orthogonal relationship; however, thisrelationship can
become nonorthogonal at very highmotor speeds due to
BEMF and PI loop lag effects, so that this orthogonal relationship between rotor and stator field can no longer be main-

May 2016

tained. As a result, the motor does not run as efficiently as it
could.
Therefore the goal of field-oriented control is to separately control the d-q (i.e., torque- and flux-producing currents) of themachine to eliminate these detrimental effects while maintaining an orthogonal relationship between the rotor and stator
flux, as governed by the following equation: Torque = Bs x Br,
where Bs and Br are vector quantities.
Another beneficial aspect of field-oriented control is the transitioning performance in between steady states and instantaneous torque control.
To achieve this controllability, sophisticated transform functions are implemented, as follows:
Clarke Transform
Is_α = Ia12Is_β = ------- × Ia + ------- × Ib
3
3

PB025504-0516

•••Park Transform
I_ds = Is_α × cos ( θ ) + Is_β × sin ( θ)I_qs = – Is_α × sinθ + Is_β × cos θ

Advantages of Field Oriented Control
Fast transient control of flux and currents from one
steady state to the next (direct torque control) especiallyin ACIM type machines• ACIM machines have intrinsically poor steady state transient performance unless operated with sophisticated controls such as FOC• Due to effects of the BEMF and the performance of current control loops at high speeds, the orthogonal relationship of the d-q axis becomes distorted unless the motor isoperated with Field Oriented Control• As with Space Vector Modulation and third harmonic
PWM sine, FOC utilizes about 15% more of the available
bus voltage, even at high speeds• As with Space Vector Modulation, FOC generates less total harmonics, acoustical and electrical noise•

Reverse Park Transform (for rectangular coordinates)
V_ds = V_dr × cos ( θ) – V_qr × sin ( θ)V_qs = V_dr × sin ( θ) + V_qr × cos ( θ)Reverse Clarke Transform (for rectangular coordinates)
V _ a = V_ds21
V_b = --- ( V_ds) + ------- ( V_qs)2321
V_c = --- ( V_ds) – ------- ( V_qs)
2
3
d-PI controller
q-PI controller

Disadvantages of Field Oriented Control• High code complexity• Higher hardware design complexity• MCU processing and resource demands are highApplications that employ Field Oriented Control• High performance industrial applications• Military

Vdr

Mag

PWM
Out

Polar
Conversion

ld_cmdVqrlq_cmdAerospace
Machine tools spindle drives
Automotive

Angle

Flux
Estimator

Park

SVM

l_ds

l_qr

l_dr

Inverter
BridgeClarke
l_qs

l_a
l_b

Speed
Integration

Tach andSpeed
Calculation

Motor
Phases A, B, C

Block Diagram: Field Oriented Control Using Polar Coordinates
Zilog Space Vector Modulation & FOC Motor Control Offerings

May 2016

Z8 Encore!

ZNEO

Z8051

Z8FMC04, Z8FMC08, Z8FMC16Z16FMC2, Z16FMC3, Z16FMC6

Z51F3220, Z51F3230

PB025504-0516

Stepper Motors
A stepper motor is an electromagnetic brushless DC motor that
divides its full rotation into a number of equal steps as it converts digital pulses into mechanical shaft rotation. The motor’s
position can then be commanded to move to and hold at one ofthese steps without a feedback sensor (i.e., an open-loop controller), as long as the motor is carefully sized to the application.
DC brushed motors rotate continuously when voltage isapplied to their terminals. Stepper motors typically convert aseries of square wave pulses into precisely-defined incrementsin the shaft position. Each pulse moves the shaft through afixed angle. Stepper motors effectively have multiple toothedelectromagnets arranged around a central gear. These electromagnets are energized by an external control circuit, such as a
microcontroller. To make the motor shaft turn, an initial electromagnet is powered, thereby magnetically attracting the
gear’s teeth. When this gear’s teeth are aligned to the first electromagnet, they are slightly offset from the next electromagnet. Therefore, when the next
electromagnet is turned on andthe initial one is turned off, thegear rotates slightly to alignwith the next one, and the process continues in a repeatedrotating cycle. Each of theserotations is called a step, with an
integer number of steps, toachieve a full rotation. With
these steps, a motor can beturned at precise angles.
There are four main types of
stepper motors:• Permanent Magnet (PM)• Variable Reluctance (VR)• Hybrid synchronous• Lavet-type
Permanent magnets in a motor’s rotor operate on the attraction or repulsion between the rotor PM and stator electromagnets. Variable Reluctance motors often feature a plain ironrotor and operate based on the principle that minimum reluctance occurs with minimum gap; as a result, the rotor points
are attracted toward the stator magnet poles. Hybrid synchronous stepper motors are so named because they use a combination of PM and VR techniques to achieve maximum power in asmall package size.
Permanent-magnet stepper motors can be further subdivided
into tin can and hybrid motor types. Tin can steppers are generally the cheaper of the two; hybrid motors generally include
higher-quality bearings, smaller step angles, and higher power
density.
Finally, Lavet-type stepping motors have widespread use as
drives in electromechanical clocks and are a special kind of single-phase stepping motor.

May 2016

Two-Phase Stepper Motors
Two basic winding arrangements exist for the electromagnetic
coils in a two-phase stepper motor: unipolar and bipolar.
Unipolar Motors. A unipolar stepper motor features one centertapped winding per phase. Each section of windings is switchedon for each direction of the magnetic field. In this arrangement,
and because a magnetic pole can be reversed without switching
the direction of the current, a simple commutation circuit (e.g.,a single transistor) can be made for each winding. Typically,
given a phase, the center tap of each winding is made common:by providing three leads per phase, or six leads, for a typical
two-phase motor. Often, these two phase commons are internally joined so that the motor has only five leads.
A microcontroller or stepper motor controller can be used toactivate the drive transistors in the right order, and this ease ofoperation makes unipolar motors popular with hobbyists; they
are probably the cheapest way to obtain precise angular movements.
Bipolar Motors. A bipolar step-

per motor features one winding
per phase. The current in thiswinding must be reversed inorder to reverse its magnetic
pole; therefore the driving circuit must be more complicated –typically with an H-bridge
arrangement. There are twoleads per phase; none are common.
Because the windings in a bipolar stepper motor are better utilized, they are more powerfulthan a unipolar motor of thesame weight due to the physicalspace occupied by the windings.
A unipolar motor requires twice
the amount of wire in the same space, but only half that wire isused at any one time; therefore a unipolar motor is 50% as efficient (or maintains approximately 70% of the available torqueoutput). Though a bipolar stepper motor is more complicatedto drive, the abundance of driver chips available on the market
makes driving a bipolar stepper much less difficult to achieve.
Higher Phase-Count Stepper Motors
Stepper motors with multiple phases tend to produce much
lower levels of vibration, though the cost of manufacture ishigher. These motors tend to be called hybrid and feature more
expensive machined parts and higher-quality bearings. Though
they are more expensive, multiphase motors effect a higher
power density and, with the appropriate drive electronics, areactually better suited to many types of applications in which
single-phase steppers are currently used.

PB025504-0516

Microstepping a Stepper Motor
Microstepping, or sine/cosine microstepping, is a stepper motor
drive technique in which the current in the motor windings iscontrolled to approximate a sinusoidal waveform. Microstepping produces a much smoother rotation than a full step drive
and provides greater resolution and freedom from resonanceproblems, due to there simply being more steps per revolution.
In a conventional full step drive, an equal amount of current isapplied to each of a motor’s stator coils. The magnetic rotoraligns itself in the coil’s magnetic field. With each motor step,current is reversed in one of the coils, and the rotor realigns to
the new magnetic field to move the rotor one motor step, or 90
degrees.
In microstepping, varying amounts of current are applied to a
motor’s coils so that the magnetic field smoothly transitions
from one polarity to the next. Each full step is now divided into
several microsteps of varying current to produce a larger number of magnetic fields that the rotor can align with. The resultis smoother motor rotation, quieter operation, and greater
motor resolution.

•
•
•
•
•
•

MedicalIndustrial machines
Scientific instrumentation
ChemicalSecurity
GamingAdvantages of Stepper Motors• Low cost
• High reliability• High torque at low speeds• Simple, rugged construction that operates in almost any
environment• Precise 360-degree positioning control• Smooth rotation at high speeds
Disadvantages of Stepper Motors• Resonance effect often exhibited at low speeds• Decreasing torque with increasing speed

Applications that employ Stepper Motors• Consumer electronics• Automotive and aircraft• Office printers and equipment

Zilog Stepper Motor Control Offerings
Z8 Encore!
Z8F2480, Z8F1680, Z8F0880

The Z32F128 ARM Cortex M3 and Z16FMC
Architectures
Zilog’s Z16FMC 16-bit and Z32F128 32-bit Cortex M3 architecture MCUs are optimized for multiphase AC and DC variable
speed motor control to provide the power, punch, and performance to satisfy the most demanding application requirements.
The ZNEO CPU boasts a highly-optimized instruction set that
achieves higher performance per clock cycle with less code spaceand lower overhead than competing architectures.
This powerful yet simple core with sixteen 32-bit general-purpose
registers supports complex CISC addressing modes and a singlecycle instruction set that includes frame pointer support, multibit
shift, and multiregister push/pop in addition to powerful 32-bit
math operations.

The Z16FMC Series features a flexible multichannel pulse widthmodulator (PWM) timer module with three complementary pairs
or six independent PWM outputs supporting deadband operationand fault protection trip input. These features provide multiphase control capability for a variety of motor types and ensure
safe operation of the motor by providing pulse-by-pulse orlatched fast shutdown of the PWM pins during fault conditions.
The Z16FMC Series also features up to twelve single-ended channels of 10-bit analog-to-digital conversion with a sample-andhold circuit, plus one operational amplifier for current sampling
and one comparator for overcurrent limiting or shutdown.
A high-speed analog-to-digital converter (ADC) enables voltage,current, and back-EMF sensing, while dual-edge interrupts and a
16-bit timer provide a Hall-effect sensor interface.
Two full-duplex 9-bit UARTs provide serial asynchronous communication and support the LIN serial communications protocol.
The LIN bus is a cost-efficient Single Master, Multiple Slaveorganization that supports speeds up to 20 Kbps.
Features

Z16FMC and Z32F128 MCUs

May 2016

The Z16FMC MCU offers the following key features:• Up to 128 KB internal Flash memory with 16-bit accessand In-Circuit Programming (ICP)• 4 KB internal RAM with 16-bit access• 12-channel, 10-bit Analog-to-Digital Converter (ADC)• Operational Amplifier
PB025504-0516

••Oscillators(XTAL, IPO)•

On-Chip
Debugger
ZNEO
CPU

POR/VBOand Reset
Controller

Interrupt
Controller

SystemClock••

WDT with
RC Oscillator•

Memory Buses•
Timers
(3)

UARTs
(2)

2

IC

ESPI

AnalogDMA

Flash
Controller

RAM
Controller

Flash
Memory

RAM

PWM
IrDA

•
•

GPIO

A Block Diagram of the Z16FMC MCU•••

Analog Comparator
4-channel Direct Memory Access (DMA)
controller
Two full-duplex 9-bit Universal Asynchronous Receiver/Transmitters(UARTs) with LIN and IrDA support
Internal Precision Oscillator (IPO)
Inter-Integrated Circuit (I2C) master/slave controller
Enhanced Serial Peripheral Interface(ESPI)
12-bit Pulse Width Modulation (PWM)
module with three complementary pairs
or six independent PWM outputs withdeadband generation and fault trip input
Three standard 16-bit timers with Capture, Compare, and PWM capability
Watchdog Timer (WDT) with internal
RC oscillator
46 General-Purpose Input/Output(GPIO) pins
24 interrupts with programmable priority
POR and VBO protection

The Z32F128 ARM Cortex M3 series
has an RISC architecture with single
cycle instructions particulary designed
for motor control.
Features• High performance low power
MCU20 Mhz internal oscillator up
to 80Mhz used with PLL– 128K Flash– 12K SRAM
• Two inverter bridges six channel
each for motor control applications configurable for:– ADC triggering functions– PWM interrupts on period
and duty cycles– Edge aligned complementarymode– Center aligned
complementary mode
– Independent PWM (up countmode)– Over voltage and over current
protection• 1.5 Msps high-speed ADC featuring up to three units
with 16 channels and burst conversion function.
May 2016

A Block Diagram of the Z32F128 MCU

PB025504-0516

•Analog Front End Peripheral– 4x OPAMPs– 4x Comparators– 6x General purpose 16-bit timers configurable for:• Capture compare• Continuous mode
• PWM mode••

Serial communications:– 4x UART– 2x SPI– 2x I2C
Quadrature Encoder for four quadrant motor operation
using 4 timers

MultiMotor Series Development Kit
Zilog’s MultiMotor Series Development Kit is built upon the
Z32F128 ARM Cortex and Z16FMC MCUs, yet is designed toallow additional MCU modules to be affixed to it for evaluationand development. These Z32F128, Z16FMC, Z8FMC 16100, andZ8051 MCU modules facilitate selection between terminal or
hardware control of the motor and a number of driving schemes
for its operation, plus the ability to monitor important motor
parameters such as:• Temperature• Speed (in RPM for trapezoidal commutation, and in frequency for sinusoidal commutation)• Current• Bus voltage• Total motor run time for maintenance-scheduling events• Direction of shaft rotation• Speed control (open or closed loop)
The MultiMotor Series Kit includes a Linix BLDC Motor

Zilog Motor Control Development Tools
ZNEO32!

Z8 Encore!

Z8051

S3

Keil MDK ARM Cortex
IAR
GCC for ARM Embedded
Third PartyZDS II – ZNEOZDS II – Z8 Encore!

Keil µVision IDE
Third Party

Third Party

Zilog Motor Control Solutions
To learn more about Zilog’s MultiMotor Series products, navigate your browser to http://zilog.com/mc, or contact your nearest Zilog
Sales Office at http://zilog.com/sales.
©2016 Zilog, Inc All rights reserved. Information in this publication concerning the devices, applications, or technology describedis intended to suggest possible uses and may be superseded. ZILOG, INC. DOES NOT ASSUME LIABILITY FOR OR PROVIDE A REPRESENTATION OF ACCURACY OF THE INFORMATION, DEVICES, OR TECHNOLOGY DESCRIBED IN
THIS DOCUMENT. ZILOG ALSO DOES NOT ASSUME LIABILITY FOR INTELLECTUAL PROPERTY INFRINGEMENT RELATED IN ANY MANNER TO USE OF INFORMATION, DEVICES, OR TECHNOLOGY DESCRIBEDHEREIN OR OTHERWISE. The information contained within this document has been verified according to the general principles of electrical and mechanical engineering.
ZNEO32!, Z8 Encore!, Z8 Encore!, XP, ZNEO, Z8051, S3, and ZDS II are trademarks or registered trademarks of Zilog, Inc.
(an IXYS Company). All other product or service names are the property of their respective owners.
May 2016

PB025504-0516