The document discusses a project to implement sensorless control of an e-bike motor using the IR3230 motor controller and HVIC driver. The goal is to reduce costs by eliminating hall sensors in the motor. A microcontroller will sense the back electromotive force (BEMF) generated in the motor windings during rotation to determine the rotor position, replacing the hall sensors. The algorithm works like a phase locked loop to continuously adjust the commutation timing to keep the zero crossings of the BEMF in the middle of switching periods. A demo board is built to test measuring the BEMF voltages and input them to the IR3230 for sensorless motor control.

1. eBike Sensorless Motor Control
Alex Lollio, Global Rotation Engineer
Automotive Products Business Unit
Provence Design Centre, France
May, 2013 - Jul, 2013
Project Manager : Andre Mourrier
Program Mentor : Massimo Grasso
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2. e-Bike Overview
Market Info:
• $8.4 billion in 2013*
• 90% of e-Bike sales in China*
48V Lit Battery
General Specifications:
• Battery 40-48V (10AH)
• Power 150W - 500W
• Input Current 10-15ARMS
• BLDC Motor
Control Board
BLDC Motor
IR Interests:
• 6 Power MOSFETS (IRFB3607)
• IC Controller and Gate Driver (IR3230)
*http://www.navigantresearch.com/research/electric-bicycles
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3. BLCD Motor Working Principle: 2 Pole
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4. IR Controller for e-Bike: IR3230
Main Features:
• Brushless DC Motor Sensor Decoder & HVIC MOSFET Driver
• Charge pump operation (No bootstrap capacitor)
• Up to 30Khz PWM switching capability (on the low switches)
• Programmable over current and over temperature protections
+5V
Yellow = sensor3
Green = sensor2
Blue = sensor1
IR3230
GND
GND
+5V
Battery power supply Battery power supply +
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5. Project Goal: Sensorless Implementation
Costumer Request:
• Sensorless driving strategy: reducing costs, simplify motor assembly and
reducing failure (most failure = Hall sensors)
Electronic Board
Sensorless Cost Saving
BLDC Motor
Power FETs: 0.2$ x 6 ≈ 1.2$
Discrete Components ≈ 0.5$
Microcontroller ≈ 0.6$
Hall Sensors: 0.4$ x 3 ≈ 1.2$
Sensors(0.15$)+Assembly(0.15$)+Cabling(0.1$)
Goal of the Project:
• Adapt IR3230 Controller & HVIC driver for a Sensorless implementation
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6. +Vbat
Cpum
p
Cd
Pmp
Vcc
Tp
CTN
Gnd_p
Shunt
Charge pump
Ground
Shtp
Rs hunt
Shtm
Vss
+5v
Power _m f et
os
Rdig_in
Diagnostic
and Reset
Flt
Rdig_in1
Flt_rst
D gi t al
i
I/O
Rdig_in2
Gls1
Ho2
Ghs2
Sk_ph2
Lo2
Gls2
Ho3
Ghs3
Sk_ph3
Gls3
Vbattery
Lo1
Lo3
SOIC28
5V Power Supply Gnd
Sk_ph1
Vs3
IR3230
IR3230
Vs1
Vs2
5.6V
Ghs1
M1
Ph1
Ph1
Ph2
Ph2
Ph3
+5v
Ph3
Gnd
Ho1
BLDC
Motor
Power
Mosfet
Out_Supply
Gnd
+
+
TºC
Measurement
IR3230 Typical Schematic
Gnd_p
120/60
+5v
Sens1
Sens2
Sens3
Gnd
Rdig_in3
Rev /Fwd
Rdig_in4
Mot/Regen
Rdig_in5
Pwm
Order input
and Selection
En
Gnd
Rdig_in6
Gndpwr
+5v
Sens1
Sens2
Sens3
Sensors interface
Gnd
Basic Idea: replacing the Hall Sensor with a Micro which senses the generated BEMF
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7. What is Back Electromagnetic Force?
A
GND
Example: Trapezoidal Motor Driving
Faraday Law:
The induced Electromagnetic Force
(EMF) is the voltage produced by
changing magnetic flux into the
windings
C
B
C
Floating
VCC
Floating phase, C, can be used to measure the
Back EMF generated by the turning rotor.
Generated Back EMF is proportional to angular
rotation speed
A
+
-
B
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8. Back EMF when duty cycle is 100%
Trapezoidal Driving
6 Step Sequence
A
A
C
Step 1
B C
Step 2
THIS GRAPH SHOWS THE VOLTAGE OF NODE PHA
High Side ON
B
PHA
VDD
BEMF crosses VDD/2
in the middle of the
switching period
A
A
VDD/2
C
Step 3
BC
A
Step 4
High Side ON
Switching Period
B
A
Low Side ON
Inductive
transient
C
Step 5
B C
B
Step 6
PHA 1
Step 2
Z
3
Inductive
transient
0
4
0
5
Z
6
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9. Back EMF @Duty=20% (low side modulation)
Trapezoidal Driving
6 Step Sequence
C
Step 1
High Side ON
A
A
B C
Step 2
THIS GRAPH SHOWS THE VOLTAGE OF NODE PHA
High Side ON
Switching Period
B
PHA
A
A
VDD/2
C
Step 3
BC
A
Step 4
B
A
Low Side PWM
C
Step 5
B C
B
Step 6
PHA
Step
1
2
Z
3
PWM
4
PWM
5
Z
6
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10. BEMF in Trapezoidal Motor Driving
Z 0 0 Z 1 1
PH1-A
PH2-B
VDD
VDD/2
1 1 Z 0 0
PH3-C
T/2
Z
0 Z 1 1 Z 0
T
Sens3
Sens1
6 STEPS
1
0
0
0
1
0
0
0
1
1
1
0
Sens2
1
1
1
1
0
0
1
2
3
4
5
6
Algorithm Strategy: VDD/2 crossing point in the middle of the switching cycle
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11. Basic Idea: Circuital Implementation
PICF1937
IR3230
RE0
RE1
RE2
VSUP
VREF
MOTOR
WINDINGS
POWER
MOSFET
RA3
SNS1
SNS2
SNS3
A
RD5
PWM
C
B
RB1 RA1 RB3
• Microcontroller compares the
BEMF voltages to the
reference voltage VREF
• When BEMF<VREF the
internal comparator generates
an interrupt (let’s call this
event “zero-cross”)
BEMF
Voltage
TS
TS/2
zero-cross
VREF
time
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12. Basic Idea: Algorithm working principle
The Back EMF tracking Algorithm works like a PLL: adjusting the
commutation period in order to keep zero-cross in the middle
TIMER1
Commutation periods
Timer1 overflow
FFFFh
Late zero-cross
Perfe
o-c
t ze r
c
r o ss
error
Perfe
-N/2
Half
commutation
preset
r o ss
ero-c
ct z
-N’/2
-N
error
-N’ = -(N+error)
0000h
Time
Full
commutation
preset
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13. Demoboard Image
Connector to ICD3
BEMF
programmer
Voltage
Divider
PHA
IR3230
PWM
Trimmer
PHB
PHC
BEMF Voltage Divider are
tested for input supply voltage
into the range 12-48V
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