ADLINK AMP-208C - Manual (Page 157)

Motion Control Theory 143
AMP-204C / AMP-208C
c. Mode 3: PWM frequency mode with fixed duty cycle
This control mode changes PWM frequency according to speed at
fixed PWM duty cycle. As shown in figure below, the duty cycle
W
1
/T
1
, W
2
/T
2
and W
3
/T
3
are the same under varying speed while
thier frequency and pulse width changes according to the VAO
table.
1. Set up control mode: Use APS_set_vao_param( ) to set
up value of VAO_TABLE_OUTPUT_TYPE parameter to 0x3 .
2. Set up fixed PWM duty cycle: Use APS_set_vao_param
( ) to set up parameter VAO_TABLE_PWM_Config in unit of
%. Valid range is 0.05% ~ 100% now.
4.9.3.3 VAO Table
The VAO table is designed to give speed-based PWM power for
VAO controller to control actual PWM output signal. The VAO
module features eight VAO tables for layered cutting. Each table
may contain up to 32 VAO pairs. See below for details on
calculating speed-based power value. In figure below the X-axis is
for composite speed of axes and the Y-axis its relevant PWM
power. Please note the unit of power varies with control modes.
Take example. If the control mode is set to mode 1: PWM mode
the corresponding power is PWM duty cycle; if the control mode is
set to mode 2: PWM frequency mode with fixed width then its
power is PWM frequency. If the composite speed V
X
is available,
its corresponding power P
x
can be interpolated as