AN1917D Freescale Semiconductor / Motorola, AN1917D Datasheet - Page 20

• Manufacturer Part Number: AN1917D
• Description: 3-Phase PM Synchronous Motor Control with Quadrature Encoder Using DSP56F80x
• Manufacturer: Freescale Semiconductor / Motorola

20
Implementation Notes
6.2.1 Constant PULSES_PER_REVOLUTION
Note:
6.2.2 Constant VOLTAGE_SHIFT
6.2.3 Constant SIN_TABLE_MULTIPLIER
The constant PULSES_PER_REVOLUTION defines the number of pulses of the Quadrature Encoder
per electrical revolution. Since the Quadrature Encoder counts both rising and falling edges, the value
is multiplied by four. The resultant value must be an integer.
In the case of presented application the constant is equal:
The constant VOLTAGE_SHIFT defines the shift of applied voltage by 90 el. degree and is calculated
as:
Then for the presented application the constant is equal to:
The constant SIN_TABLE_MULTIPLIER rescales the rotor position, which is defined in pulses per
electrical revolution, to the sinewave table, which is scaled from -1 to 1 <- ; ). Detailed information
about sinewave generation can be found in the SDK documentation [11]. The constant is calculated as:
For the presented calculation can be calculated:
PULSES_PER_REVOLUTION
In case that the constant is not an integer, it is necessary to set the constant
PULSES_PER_REVOLUTION to a value which is equal to the number of pulses per
mechanical revolution minus one. Then the actual rotor position has to be recalculated from
the mechanical to electrical revolution.
SIN_TABLE_MUTIPLIER
VOLTAGE_SHIFT
3-Phase PMSM Control with Quadrature Encoder
SIN_TABLE_MUTIPLIER
Freescale Semiconductor, Inc.
PULSES_PER_REVOLUTION
For More Information On This Product,
VOLTAGE_SHIFT
Go to: www.freescale.com
=
=
4
----------------------------------------------------------------------------------------------------- - 1
=
-----------------------------------------------------------------------------------------
PULSES_PER_REVOLUTION
-------------------------------------------------------------------------- -
PULSES_PER_REVOLUTION
number of pulses per mech. revolution
=
number of pole pairs
---------------------- -
999
=
65535
4
65535
-------------- -
=
+
999
4
1
4
----------------- - 1
=
2
500
250
256
–
=
=
16794
+
999
1
256
–
MOTOROLA
(EQ 6-3.)
(EQ 6-4.)
(EQ 6-5.)