NXP Semiconductors MC56F8013, 56F8000 Targeting User Manual

3-Phase BLDC Motor Control
with Hall Sensors Using the
MC56F8013

Targeting User Guide

56F8000

16-bit Hybrid Controllers

56F8013BLDCUG
Rev. 1
11/2005

freescale.com

TABLE OF CONTENTS

About This Book

Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface-v

Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface-v

Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface-v

Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface-vi

Definitions, Acronyms, and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface-vii

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preface-vii

Chapter 1
Introduction

1.1 Application Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Chapter 2
System Description

2.1 Application Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

2.2 Hardware Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

2.3 Software Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

2.3.1 Data Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Chapter 3
Setting Up the Application

3.1 Required Parts and Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Chapter 4
Running the Application

4.1 BLDC with Hall Sensor Demonstration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Freescale Semiconductor i
Preliminary

Table of Contents, Rev. 1

ii Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

LIST OF FIGURES

2-2 System Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2-3 Main Data Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2-4 Speed Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

3-1 56F8000 Motor Control Daughter Card and 56F8013 Demonstration Board . . . . . . . . 3-1

Freescale Semiconductor iii
Preliminary

List of Figures, Rev. 1

iv Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

About This Book

This manual describes the applications for 3-Phase BLDC motor control with Hall sensors using
the 56F8013 device.

Audience

This document targets software developers using 3-Phase BLDC motor control for the 56F8013
processor.

Organization

• Chapter 1, Introduction—provides a brief overview of this document

• Chapter 2, System Description—describes the theory of BLDC motor control with Hall
sensors for the 56F8013 processor

• Chapter 3, Setting Up the Application—explains how to set up the application

• Chapter 4, Running the Application—describes how the BLDC with Hall Sensor
application operates

Suggested Reading

We recommend that you have a copy of the following references:

• 56F8013 Technical Data, MC56F8013

• 56F8013 Motor Control Demonstration System using the 56F8013 Demonstration Board
User Guide, 56F8013MCSUG

• 3-Phase BLDC Motor Control with Hall Sensors using 56800/E Digital Signal Controllers,
AN1916

• 56F8000 Peripheral Reference Manual, MC56F8000RM

• Inside CodeWarrior: Core Tools, Metrowerks Corp.

Preface, Rev. 1

Freescale Semiconductor v
Preliminary

Conventions

This document uses the following notational conventions:

Typeface,

Symbol or Term

Courier
Monospaced
Type

Italic Directory names,

Code examples //Process command for line flash

project names,
calls,
functions,
statements,
procedures,
routines,
arguments,
file names,
applications,
variables,
directives,
code snippets
in text

Bold Reference sources,

paths,
emphasis

Meaning Examples

...and contains these core directories:
applications contains applications software...

...CodeWarrior project, 3des.mcp is...

...the pConfig argument....

...defined in the C header file, aec.h....

...refer to the Targeting DSP56F80x Platform

manual....

...see: C:\Program Files\Motorola\help\tutorials

Blue Text Linkable on-line ...refer to Chapter 7, License....

Number Any number is consid-

ered a positive value,
unless preceded by a

3V

-10

DES

-1

minus symbol to signify
a negative value

ALL CAPITAL
LETTERS

# defines/
defined constants

# define INCLUDE_STACK_CHECK

Brackets [...] Function keys ...by pressing function key [F7]

Quotation

Returned messages ...the message, “Test Passed” is displayed....

marks, “...”

...if unsuccessful for any reason, it will return
“NULL”...

vi Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Definitions, Acronyms, and Abbreviations

The following list defines the acronyms and abbreviations used in this document. As this template
develops, this list will be generated from the document. As we develop more group resources, these
acronyms will be easily defined from a common acronym dictionary. Please note that while the acronyms
are in solid caps, terms in the definition should be initial capped ONLY IF they are trademarked names or
proper nouns.

BLDC Brushless DC Motor

PI Proportional-Integral

PWM Pulse Width Modulation

References

The following sources were used to produce this book:

1. 56F8000 Peripheral Reference Manual, MC56F8000RM, Freescale Semiconductor, Inc.

2. 56F8013 Demonstration Board User Guide, MC56F8013DBUG, Freescale Semiconductor, Inc.

3. 56F8000 Motor Control Board User Guide, 56F8000MCBUG, Freescale Semiconductor, Inc.

4. DSP56800E Reference Manual, DSP56F800ERM, Freescale Semiconductor, Inc.

5. 56F8013 Technical Data, MC56F8013, Freescale Semiconductor, Inc.

6. 3-Phase BLDC Motor Control with Hall Sensors using 56800/E Digital Signal Controllers,

AN1916, Freescale Semiconductor, Inc.

7. 56800/E Accelerated Development System Resource Pak CD-ROM, CD342, Freescale
Semiconductor, Inc. (available from the Literature Distribution Center)

Freescale Semiconductor vii
Preliminary

Preface, Rev. 1

viii Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Chapter 1
Introduction

1.1 Application Benefits

This document describes the design of a 3-phase BLDC (Brushless DC) motor control applciation
with Hall Sensors, and explains how it is targeted for Freescale’s 56F8013 dedicated motor

control device. The software design takes advantage of the Processor Expert
included with CodeWarrior.

The theoretical concepts of this application are explained in an application note 3-Phase BLDC
Motor Control with Hall Sensors using 56800/E Digital Signal Controllers, found on the
Freescale Semiconductor web site:

www.freescale.com

TM

(PE) tool,

Freescale Semiconductor 1-1
Preliminary

Introduction, Rev. 1

Introduction

1-2 Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Chapter 2
System Description

The system is designed to drive a 3-phase BLDC motor. The application meets the following performance
specifications:

• Speed/Voltage control of BLDC motor using Hall sensors

• Torque/Current control

• Start from any motor position without rotor alignment

• DCBus undervoltage fault protection

• Real-time application monitoring via the PC master software application

The BLDC drive introduced in this manual is designed to power a low-voltage BLDC motor equipped
with Hall sensors, which is supplied with the Motor Control Daughter Card. The motor has the following
specifications:

Table 2-1. Motor Information

M1

Characteristic Typical Value Units

Power Rating 6 W

Nominal Voltage 9.0 Volt

No-Load Speed 8600 rpm

Stall Torque 20 mNm

Speed / Torque Gradient 479.0 rpm / mNm

No-Load Current 110 mA

Terminal Resistance
Phase-to-Phase

Maximum Permissable Speed 12000 rpm

Maximum Continuous Current at 5000rpm 1.03 A

Maximum Continuous Torque at 5000rpm 8.70 mNm

Maximum Efficiency 60.0 %

Torque Constant 9.5 mNm / A

Speed Constant 1007 rpm / v

System Description, Rev. 1

4.50 Ohm

Freescale Semiconductor 2-1
Preliminary

System Description

Table 2-1. Motor Information (Continued)

M1

Characteristic Typical Value Units

Mechanical Time Constant 70.0 ms

Rotor Inertia 13.9

Terminal Inductance
Phase-to-Phase

Thermal Resistance Housing
Ambient

Thermal Resistance
Winding-Housing

Thermal Time Constant
Windings

Thermal Time Constant
Stator

1.070 mH

6.8 K / W

7.4 K / W

3.7 s

16.1 s

gcm

2

2.1 Application Description

A standard system concept is chosen for the drive; see Figure 2-2. The system incorporates the following
hardware:

• 9V DC Power Supply

• 56F8000 Motor Control Daughter Card (Part #APMOTOR56F8000)

• Demostration board for MC56F8013 (Part #DEMO56F8013 or DEMO56F8013-E)

The 56F8013 runs the main control algorithm and generates 3-phase PWM output signals for a 3-phase
inverter according to the user interface and feedback signals.

3-Phase BLDC Motor Control, Rev. 1

2-2 Freescale Semiconductor

Preliminary

DEMO56F8013

DEMO56F8013

PC Remote

PC Remote

Monitoring

Monitoring

Fault

Fault

LED

LED

Speed

Speed

Control

Control

56F8013

56F8013

S

S
C

C

I

I

G

G
P

P

I

I

O

O

PI (Torque)

PI (Torque)

Controller

Controller

PI (Speed)

PI (Speed)
Controller

Controller

Ω

Ω

Duty Cycle

Duty Cycle

Ω

Ω

Act

Act

Req

Req

Commutation

Commutation

Handler

Handler

Under-Voltage

Under-Voltage

Fault Detection

Fault Detection

Speed

Speed

Calculation

Calculation

Application Description

9V DC

9V DC

PWM1-6

PWM1-6

P

P
W

W
M

M

DC Bus Voltage

DC Bus Voltage

A

A
D

D
C

C

T

T

I

I

M

M
E

E
R

R

DC Bus Current

DC Bus Current

Hall Sensors

Hall Sensors

APMOTOR56F8000

APMOTOR56F8000

Motor Control

Motor Control

Daughter Card

Daughter Card

BLDC

BLDC
motor

motor

Figure 2-2. System Concept

The control process is as follows:

The state of the user interface is periodically scanned, while the speed of the motor is measured with each
new edge from the Hall sensors; only one phase is used for speed measurement. The speed command is
calculated according to the state of the control signals. The comparison between the actual speed
command and the measured speed generates a speed error, which is input to the PI Speed controller that
acts as an input to the PI Torque controller. Together with measured current, it forces the PI Torque
controller to generate a new corrected duty cycle. The duty cycle value, together with the commutation
algorithm, creates the PWM output signals for the BLDC power stage.

The Hall sensor signals are scanned independently of speed and torque controls. Each new coming edge
of any Hall sensor signal calls the interrupt routine, which executes the commutation algorithm.

If undervoltage occurs, the PWM outputs are disabled and the fault state is displayed.

Freescale Semiconductor 2-3
Preliminary

System Description, Rev. 1

System Description

2.2 Hardware Design

This application utilizes the following HW modules:

• 56F8000 Motor Control Daughter Card (Part #APMOTOR56F8000)

• Demostration board for 56F8013 (Part #DEMO56F8013 or DEMO56F8013-E)

Refer to corresponding User Manual for more information on these boards.

2.3 Software Design

This section descibes the design of software blocks.

2-4 Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Software Design

2.3.1 Data Flow

The control algorithm of a closed-loop BLDC drive is described in Figure 2-3. The individual processes are
described in the following sections.

DCBus
Current

ADC Conversion

Interrupt

Calculate Moving

Average

ADCAvg

Speed

Setting

via

Button

Calculate Desired

Speed

DesiredVoltageFraction

PI Speed Controller

PI Speed Controller

Calculate Actual

Speed

MeasuredVoltageFraction

Hall

Sensors

Capture Interrupt

SensorState

Mask and Swap

Calculation

DCBus

Voltage

ADC Conversion

Interrupt

Calculate Moving

Average

DCBusAvg

Overvoltage

Fault?

PI Torque
Controller

Calculate Duty

Cycle

Figure 2-3. Main Data Flow

The main data flow can be divided into five parts:

• Speed control

• Torque control

• Velocity calculation

• Rotor commutation

• DCBus voltage measurement

System Description, Rev. 1

DutyCycle

Yes

Shutdown PWM

PWM

Generation

Freescale Semiconductor 2-5
Preliminary

System Description

Speed control starts with the DesiredVoltageFraction variable, which is set by the user button. This
variable is used as one of the inputs to a Speed PI controller. The second input to the Speed PI controller
is the MeasuredVoltageFraction variable, which is derived from the Velocity Calculation algorithm.

Velocity calculation is done by counting CPU clocks between the edges on one of the Hall Sensor phases
(phase A). With a 4-pole motor, there are eight speed captures per one mechanical revolution, as shown in

Figure 2-4:

Speed

Capture

Hall Sensor

Phase A

Hall Sensor

Phase B

Hall Sensor

Phase C

Commutation

1

1

2

3

1 Electrical Rev.

2

4

3

1

5

6

4

2

3

4

5

1 Electrical Rev.

1 Mechanical Revolution

5

6

1

6

2

3

4

5

1 Electrical Rev.

7

6

1

8

2

3

4

5

1 Electrical Rev.

6

At a maximum speed of 8600rpm, each timer capture should have a count of 218, calculated as follows:

9V = 8600rpm or 143.3 revolutions per second

By performing eight speed captures per revolution, there are 1146.6 captures per second, which translates
to 872µsec per capture.

Since the capture timer is running at 250KHz or 32MHz / 128, a maximum rate of 8600 rpm will translate
to 218 timer ticks for each capture.

To find the actual voltage fraction, divide 218 by the measured timer ticks. For example, if 218 timer
ticks are measured, the voltage fraction is 1, or 100% (9V). If 436 timer ticks are measured, the voltage
fraction is 0.5, or 50% (4.5V)

2-6 Freescale Semiconductor

Figure 2-4. Speed Capture

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Software Design

The output from the Speed PI controller is used as one of the inputs to a Torque PI controller. The second
input to the Torque PI controller is the ADCAvg variable, which is derived from the DCBus current’s
moving average algorithm. The Torque PI controller’s output determines the duty cycle of the generated
PWM output signals.

The rotor commutation process performs mask and swap calculations’ control. The proper PWM output
can be generated by changing the PWM value (duty cycle) registers only. This has two disadvantages:
The first is that the speed controller, which changes the duty cycle, affects the commutation algorithm
(performed by changing the duty cycle). The second disadvantage is that a change in the duty cycle is
synchronized with PWM reload, which may cause a delay between a proper commutation moment and
the PWM reload. This is especially pronounced at high speed when the commutation period is very short.

The 56F801x device has two features dedicated to BLDC motor control: the ability to swap odd and even
PWM generator outputs and the ability to mask (disable) any PWM generator outputs. These two features
allow creation of a rotational field without changing the contents of the PWM value registers. The
commutation algorithms calculate PWM mask and swap values based on the SensorState variable and the
ClockWiseCommTable look-up table. The mask and swap values are written into the PWM Channel
Control Register.

The DCBus voltage measurement acts as a fault detection, which disables PWM if voltage drops below
7V.

Freescale Semiconductor 2-7
Preliminary

System Description, Rev. 1

System Description

2-8 Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Chapter 3
Setting Up the Application

3.1 Required Parts and Instructions

To run this application, the user will need the 56F8013 Demonstration Board (DEMO56F8013 or
DEMO56F8013-E) and the 56F8000 Motor Control Daughter Card (APMOTOR56F8000). These parts
can be ordered through the Freescale website.

Please follow the instructions printed in the kit installation guide included in each kit to install and
connect both boards, as well as to install CodeWarrior development tools.

The final set up should look like in the picture in Figure 3-1. Please the use default settings shown in the
56F8013 Demonstration Board User Guide.

Figure 3-1. 56F8000 Motor Control Daughter Card and 56F8013 Demonstration Board

Freescale Semiconductor 3-1
Preliminary

Apply power here

Setting Up the Application, Rev. 1

Setting Up the Application

3-2 Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

Chapter 4
Running the Application

4.1 BLDC with Hall Sensor Demonstration

Once this demonstration application is downloaded into the 56F8013 Demonstration Board,
(DEMO56F8013), the user can control the speed of the BLDC motor by pressing and releasing the IRQ
#2 button (S2) located on the demonstration board. Button control works as follows:

• Initially pressing and releasing the IRQ #2 button increases rotation speed

• Motor speed increases each time the IRQ #2 button is pressed, until the motor reaches maximum
speed

• Once maximum speed is reached, motor speed decreases each time the IRQ #2 button is pressed,
until the motor stops

Freescale Semiconductor 4-1
Preliminary

Running the Application, Rev. 1

Running the Application

4-2 Freescale Semiconductor

3-Phase BLDC Motor Control, Rev. 1

Preliminary

INDEX

Numerics

3-Phase BLDC Motor Control with Hall Sensors using

56800/E Digital Signal Controllers

56800/E Accelerated Development System Resource

Pak CD-ROM

56F8000 Motor Control Board User Guide Preface-vii
56F8000 Peripheral Reference Manual Preface-vii
56F8013 Demonstration Board User Manual Preface-vii
56F8013 Technical Data Preface-vii

Preface-vii

B

BLDC Preface-vii, 1-1
Brushless DC Motor

BLDC Preface-vii, 1-1

D

DSP56800E Reference Manual Preface-vii

Preface-vii

P

PI Preface-vii
Proportional-Integral

PI Preface-vii

Pulse Width Modulation

PWM Preface-vii

PWM Preface-vii

Freescale Semiconductor Index-1
Preliminary

Index, Rev. 1

Freescale Semiconductor Index-2
Preliminary

Index, Rev. 1

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© Freescale Semiconductor, Inc. 2005. All rights reserved.

56F8013BLDCUG
Rev. 1
11/ 200 5