AN1913D Freescale Semiconductor / Motorola, AN1913D Datasheet - Page 3

• Manufacturer Part Number: AN1913D
• Description: 3-phase BLDC Motor Control with Sensorless Back-EMF ADC Zero Crossing Detection using DSP 56F80x
• Manufacturer: Freescale Semiconductor / Motorola

3.
3.1 BLDC MotorTargeted by This Application
The PWM module is capable of providing the six PWM signals with bipolar switching (the diagonal
power switches are driven by the same signal). In addition, the PWM provides the six-step BLDC
commutation control (where one motor phase is left unpowered so the Back-EMF can be detected).
The PWM duty cycle can be set asynchronously to the commutation of the motor phases event using
the channel swap feature.
An Analog-to-Digital Converter (ADC) module has the following features:
The Analog-to-Digital Converter is utilized to measure DC-Bus voltage, DC-Bus current and the
power module temperature. The ADC’s Hi/Lo level detection capability provides automatic detection
of the over/under-voltage, over-current and over temperature protection (serviced in associated ISR).
The Brushless DC motor (BLDC) is also referred to as an electronically commuted motor. There are
no brushes on the rotor and the commutation is performed electronically at certain rotor positions. The
stator is usually made from magnetic steel sheets. The stator phase windings are inserted in the slots
(distributed winding) as shown on
magnetization of the permanent magnets and their displacement on the rotor is chosen so that the
Back-EMF (the voltage induced into the stator winding due to rotor movement) shape is trapezoidal.
This allows the DC voltage (see
field with low torque ripples
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Target Motor Theory
Deadtime distortion correction using current status inputs or software
Separate top and bottom polarity control
Edge-aligned or center-aligned PWM reference signals
15-bit resolution
Half-cycle reload capability
Integral reload rates from one to 16 period
Individual, software-controlled PWM output
Programmable fault protection
20-mA current sink capability on PWM pins
Write-protectable registers
Dual ADCs per module
Eight input channels per module
12-bit resolution
Monotonic over entire range with no missing codes
Simultaneous conversion mode
Single conversion time in 1.7 us; eight conversions in 5.3 us (using simultaneous mode)
Interrupt generating capabilities at: end-of-scan, Zero Crossing, and high/low limit check
Two output formats: two’s compliment and unsigned
BLDC control with BEMF Zero Crossing using ADC
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure
Figure 3-1
Go to: www.freescale.com
3-2), with a rectangular shape, to be used to create a rotational
or it can be wound as one coil on the magnetic pole. The
Target Motor Theory
3