Proportional Control Of Speed - Toshiba Tosvert RS485 Instruction Manual

6.1. Proportional control of speed

Proportional control of frequency can be performed in two ways: control by selecting frequency
points and control by adjusting the ratio to the maximum frequency. This section explains propor-
tional control of inverters by means of a master inverter (inter-drive communication), although the
AS1 series inverters are ready for proportional control by means of the "S" command even when
they are operated under the control of a computer (computer-linked communication) (in the latter
cases, read the master inverter as the computer).
Proportional control can also be performed in units of Hz using ordinary write commands (W and P
commands) (frequency point selection only). For proportional control in units of %, however, the S
command should be used.
* For proportional control by selecting frequency points, the gradient can be set variously according
to the way each inverter is used. For proportional control by controlling the ratio to the maximum
frequency, settings can be made easily without consideration of the rate at which the frequency is
increased or decreased to the target frequency.
• Data sent by the master inverter to slave inverters in inter-drive communication mode (frequency
command value)
fc (%)
* Fractions under 1 (0.01%) are omitted. Therefore, an error of 0.01% is introduced at the maxi-
mum.
• Conversion of the frequency command received by a slave inverter (when the "frequency point
selection" option is not selected)
The value obtained by the following conversion calculation is written in RAM as a frequency com-
mand value.
( fc
* Fractions under 1 (0.01Hz) are omitted. Therefore, an error of 0.01Hz is introduced at the maxi-
mum.
[Diagram of speed proportional control]
<Outside> ← →<Inverter's internal computation>
Operation performed by the slave
Operation performed by the
master (or use of S command)
fc %
Master
× 0
Master send data＝ 1000
Master FH
%
Master side fc 10000
×
＝
Master side FH
Slave receive data (%)
=
Hz )
10000
Slave receive data
×
Data ( Hz ) ＝ Slave FH
10000
(1=0.01%)
×
Slave side FH
(1=0.01Hz)
* fc=frequency reference, FH=maximum frequency
Hz
Point conversion
(Hz)
fc ( )
Setting 2

Slave command
fc ( )
Setting 1

(

fc
− Po int
Point 2
Slave command＝
−
Point2 Point1
fc
Hz
×
Data＝ 10 000
Slave FH
37
Point selection ()
Points not selected
Point1 Point2
(%)
) )
(
Master command
fc
1
fc
×
( Master command －Point1）＋P oint 1
%
E6581315
Fc
(Hz)
Points selected
Hz