AN1917D Freescale Semiconductor / Motorola, AN1917D Datasheet - Page 19

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

MOTOROLA
6.1.1 DC-Bus Voltage Scaling
6.1.2 PI Controller Parameters
6.1.3 Velocity Calculation
6.2 Motor Constant Calculation
where:
Fractional Value is a fractional representation of the real value [Frac16]
Real Value is the real value of the quantity [V, A, RPM, etc.]
Real Quantity Range is the maximum range of the quantity, defined in the application [V, A, RPM,
etc.]
The DC-Bus voltage sense is defined by the following equation:
Where: u_dc_bus = variable of DC-Bus voltage, V
measurable DC-Bus voltage.
V
The P constant was chosen as 0.2 (26214 * 2
0.12 (31457 * 2
actual speed. The I constant equals 0.3 from 50 to 200 RPM. Over 200 RPM the I constant equals 0.12.
The controller parameters were experimentally tuned.
The constant OMEGA_ACTUAL_MECH_CONST is defined by the following equations:
position difference = 1/500 rev (given by each rising edge of one phase of Quadrature Encoder and two
pole pairs motor)
max. period time = 0.008 s (chosen according to required min. speed)
v
v
OMEGA_ACTUAL_MECH_CONST = 32767*v
The PM Synchronous motor control application uses the constants, which depend on a motor type
(number of pole pairs) and on a Quadrature Encoder type (number of pulses per revolution). The
depended constants are:
The following paragraphs explain the constant calculations. The range for all constants is unsigned
integer.
min
max
MAX
•
•
•
= 60*(position difference)/(max. period time) = 15 RPM
= 100*v
= 16V for the EVM Motor Board
PULSES_PER_REVOLUTION
VOLTAGE_SHIFT
SIN_TABLE_MULTIPLIER
min
-18
= 1500 RPM (chosen according to required max. speed)
). To get better response to error speed, the I constant is changed according the
3-Phase PMSM Control with Quadrature Encoder
Freescale Semiconductor, Inc.
For More Information On This Product,
u_dc_bus
Go to: www.freescale.com
=
V DC_BUS
--------------------------- - 32767
-17
min
V MAX
) and the I constant was chosen as 0.3 (31457 * 2
/v
DC_BUS
max
= 327
= measured DC-Bus voltage, V
Implementation Notes
MAX
= max.
-20
) or
19