Microchip Technology DM183021 User Manual
PICDEM™ MC LV
DEVELOPMENT BOARD
© 2006 Microchip Technology Inc.
DS51554B-page 27
Chapter 7. Using dsPIC DSCs to Run a Sensorless BLDC Motor
7.1
INTRODUCTION
The PICDEM MC LV Development Board can be used to run a BLDC motor without a
Hall effect sensor. To find out more and get a full description of the application, refer to
Application Note
Hall effect sensor. To find out more and get a full description of the application, refer to
Application Note
AN992, “Sensorless BLDC Motor Control Using dsPIC30F201
0”
(DS00992). For jumper settings and details on how to connect the motor, refer to
Chapter 6. “Getting Started with dsPIC Digital Signal Controllers”.
Chapter 6. “Getting Started with dsPIC Digital Signal Controllers”.
In this chapter, we will briefly explain how a sensorless BLDC motor application is run
using a dsPIC device and describe how to adjust some of the parameters in order to
make specific BLDC motors run. For more details on the hardware and firmware
specifications, refer to Application Notes
using a dsPIC device and describe how to adjust some of the parameters in order to
make specific BLDC motors run. For more details on the hardware and firmware
specifications, refer to Application Notes
AN901, “Using the dsPIC30F for Sensorless
BLDC Contro
l” (DS00901) and AN992, “Sensorless BLDC Motor Control Using
dsPIC30F201
0” (DS00992). These Application Notes can be found on the Microchip
web site (www.microchip.com).
7.2
HIGHLIGHTS
This items discussed in this chapter are:
7.3
SENSORLESS CONTROL OF A BLDC MOTOR
To run a BLDC motor without sensors, it is important to sense the rotor magnet position
with reference to the windings on the stator. In order to do this properly, the Back EMF
on the unexcited winding is monitored. As the motor is spun, the voltage waveform on
the three winding phases will be seen, as shown in an idealized manner in Figure 7-1.
with reference to the windings on the stator. In order to do this properly, the Back EMF
on the unexcited winding is monitored. As the motor is spun, the voltage waveform on
the three winding phases will be seen, as shown in an idealized manner in Figure 7-1.
FIGURE 7-1:
ZERO-CROSSING DETECTION
5
0
1
2
3
4
5
0
1
Sector
0
0
0
= BEMF Zero Crossing
30°