Motorola M68HC08 - Manual (Page 17)

System Description
System Specification
DRM028 — Rev 0 Designer Reference Manual
MOTOROLA System Description 17
The A/D converter is also used to sense the dc-bus voltage and the drive
temperature. The dc-bus voltage is stepped down to a 3.3-V signal level
by a resistor network.
The six IGBTs (copack with built-in fly back diode), or MOSFETs, and
gate drivers create a compact power stage. The drivers provide the level
shifting that is required to drive the high side switch. The PWM technique
is used to control motor phase voltage.
2.3 System Specification
The concept of the application is that of a speed-closed loop drive using
back-EMF zero crossing technique for position detection. It serves as an
example of a sensorless BLDC motor control system using Motorola’s
MC68HC908MR32 MCU. It also illustrates the usage of dedicated motor
control on-chip peripherals.
The system for BLDC motor control consists of hardware and software.
The application uses universal modular motion control development
hardware boards, which are provided by Motorola for customer
development support. For a description of these hardware boards refer
to
Appendix A. References 3. , 4. , 5. , 6. , 7. , and the World Wide Web at:
http://www.motorola.com
There are three board and motor hardware sets for the application:
1. High-Voltage Hardware Set — For variable line voltage 115–230
Vac and medium power (phase current < 2.93 A)
2. Low-Voltage Evaluation Motor Hardware Set — For automotive
voltage (12 V) and very low power (phase current < 4 A)
3. Low-Voltage Hardware Set — For automotive voltage (12 V or
possibly 42 V) and medium power (phase current < 50 A)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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