Information

8 Automotive Capabilities
The on-chip A/D converter samples the motor phase
voltages. From the voltages, the CPU determines the
rotor position and drives the motor control PWM module
to generate trapezoidal output signals for the 3 phase
inverter circuit.
FIR Filtering of the BEMF helps with high-speed motors
or motors with distorted BEMF signals. Majority Detect
reduces the amount of time on motor tuning.
BLDC Fan Control
Need a highly integrated fan controller with a
customizable speed/temperature profi le? Take a
look at the PIC12HV and PIC16HV families. With a
on-chip 5V regulator and comparator, the system
designer is able to reduce components on the board
and associated system costs. The rotor position is
determined by a Hall effect sensor connected to the
on-chip comparator. The Enhanced Capture Compare
PWM (ECCP) peripheral uses the feedback information
to drive the motor by steering the PWM signal to the
appropriate motor phase. Temperature sensor inputs
can be used to create a unique fan profi le and the PIC
MCU processes the information and transfers digital
status to the vehicle’s body computer module.
The trend toward a beltless vehicle continues to build
momentum as the demand for innovative solutions
with a small footprint to support the consumer’s
demand for improved fuel economy and reduced
emissions, PICmicrocontrollers and dsPIC® digital
signal controllers provide an innovative suite of on-chip
peripherals coupled with wide range of performance
options that support the development of precision
motor control systems. BLDC motors usage is growing
due to the affordability of their operations being more
energy effi cient, quieter, with a greater range and
extended life.
For example, in a brushless fuel pump design, the
innovative electronically commutated three phase
motor eliminates the need for mechanical brushes. As
a result, reduced power consumption is achieved due
to the elimination of friction caused by the brush to
commutator interface and functionally enhanced due
to the ability to have variable output to allow the fuel
pump to operate at speeds which match the engine’s
demand. Plus with Microchip’s sensorless fi eld-oriented
control algorithm which uses the single cycle MAC
with data saturation, zero overhead looping and barrel
shifting to achieve stunning performance.
The broad
product
portfolio of
microcontroller
and analog
devices from
Microchip
enables creative
solutions for
motor control
challenges
within the
vehicle. The Enhanced Capture Compare PWM
Peripheral (ECCP) module found on some devices in
the PIC16/18 families of microcontrollers is optimized
for controlling ½ bridge or H bridge motor drive circuits.
Plus it can be used for BLDC motor commutation or
stepper motor control as shown in the brushless fan
control illustration.
BLDC Sensorless
Want to reduce the vehicle weight and cost of Hall
effect sensors and wiring harness cabling by going
sensorless? Take a look at the PIC18, PIC24 or
dsPIC33 families for your sensorless BLDC solutions.
FIR fi ltering of the BEMF and/or using Majority Detect
can help with high speed motors or motors with
distorted BEMF signals.
Supporting the Advancements Toward a Beltless Vehicle
N
S
Hall
Sensor
PIC
®
MCU
12V DC
A
B
Temperature
PW M Command
I
2
C™
Commutation
& Speed
5V Reg
ECCP
Comp
Fan Control Application Using PIC® MCUs
www.microchip.com/motorcontrol
3-ph
Inverter
IBUS
BLDC
Demand
Fault
VDC
PIC18F MCU or
dsPIC
®
DSC
Phase Terminal Voltage Feedback
PWM3H
PWM3L
PWM2H
PWM2L
PWM1H
PWM1L
FLTA
AN0
AN1
AN2
AN12
AN13
AN14
3-Phase BLDC with BEMF
T
p
p
m
a
d
M
e
s
m
c
w
dsPIC33F/
dsPIC30F
DSC
PIC16F
MCU
PIC18F
MCU
Relative
Cost
Sensorless BLDC, Back EMF
Application/Control Complexity
Low Speed High Speed
FOC