Delta Tau GEO BRICK LV User Manual
Geo Brick LV User Manual
Motor Setup
157
Dominant Clock Settings
The choice of clock settings usually relies on system requirements, and type of application.
Calculating Minimum PWM Frequency
The minimum PWM frequency of a system is based on the time constant of the motor. In general, the
lower the time constant, the higher the PWM frequency should be. The motor time constant is calculated
dividing the motor inductance by the resistance (phase-phase). The minimum PWM Frequency is then
determined using the following relationship:
lower the time constant, the higher the PWM frequency should be. The motor time constant is calculated
dividing the motor inductance by the resistance (phase-phase). The minimum PWM Frequency is then
determined using the following relationship:
Ohms
R
H
L
sec
sec
2
20
)
(
2
20
Hz
PWM
PWM
Example: A motor with an inductance of 2.80 mH, resistance of 14
(phase-phase) yields a time
constant of 200
sec. Therefore, the minimum PWM Frequency is about ~15.9KHz.
Recommended clock Frequencies
The most commonly used and recommended clock settings for the Geo Brick LV are 20 KHz PWM, 10
KHz Phase, and 5 KHz Servo.
KHz Phase, and 5 KHz Servo.
I6800=1473
; Macro IC0 Max Phase/PWM Frequency Control
I6801=3
; Macro IC0 Phase Clock Frequency Control
I6802=1
; Macro IC0 Servo Clock Frequency Control
I7100=1473
; Servo IC1 Max Phase/PWM Frequency Control
I7101=3
; Servo IC1 Phase Clock Frequency Control
I7102=1
; Servo IC1 Servo Clock Frequency Control
I7000=1473
; Servo IC0 Max Phase/PWM Frequency Control
I7001=3
; Servo IC0 Phase Clock Frequency Control
I7002=1
; Servo IC0 Servo Clock Frequency Control
I10=1677653
; Servo Interrupt Time
Note that downloading parameters to a non-existent Servo or Macro IC is usually neglected by PMAC but
it is not a good practice for documentation and future configuration downloads. Use/download only the
parameters pertaining to the IC’s present on your unit:
Condition
Use/Download
Description
I4900=$1 and I4902=$0
I7000s
Servo IC 0 present
I4900=$3 and I4902=$0
I7100s and I7000s
Servo ICs 0, and 1 present
I4900=$1 and I4902=$1
I6800s and I7000s
Servo IC 0 and Macro IC 0 present
I4900=$3 and I4902=$1
I6800s, I7100s and I7000s
Servo ICs 0, 1 and Macro IC 0 present
Clock Calculations
The following clock calculations are used in selected downloadable scripts in subsequent section(s). Thus,
it is highly recommended to adjoin them to your downloadable file:
it is highly recommended to adjoin them to your downloadable file:
I15=0
; Trigonometric calculation in degrees
#define MaxPhaseFreq P8000 ; Max Phase Clock [KHz]
#define PWMClk
#define PWMClk
P8001 ; PWM Clock [KHz]
#define PhaseClk
P8002 ; Phase Clock [KHz]
#define ServoClk
P8003 ; Servo Clock [KHz]
MaxPhaseFreq=117964.8/(2*I7000+3)
PWMClk=117964.8/(4*I7000+6)
PhaseClk=MaxPhaseFreq/(I7001+1)
ServoClk=PhaseClk/(I7002+1)