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Chapter 4
The speed control normally incorporates the proportional integrated
compensation (PI control), and the motor speed is controlled so that the
difference between the frequency specified by the frequency command
and the actual motor speed is zero. However, a specific operation mode
(called drooping operation), in which one load is driven by multiple motors,
sometimes requires the proportional control (P control). To enable the
proportional (P) control mode, assign function "43" (P/PI switching
function) to one of the terminal [1] to [8] functions (C001 to C008), and
turn on the intelligent input terminal. For the proportional control, set the
value of the P control proportional gain (H052) as the KPP value.
The following formula generally represents the relation between the KPP
value and momentary speed variation:
(Momentary speed variation) =
The following formula generally represents the relation between the momentary speed variation and speed error:
(Momentary speed variation) =
4.2.56 Analog command holding function (AHD)
- The analog command holding function allows you to make the inverter hold the
analog command input via the external analog input terminal when the AHD
terminal is on.
- While the AHD terminal is on, the up/down function can be used based on the analog signal held by this function as reference
data.
- When "01" is specified for Up/Down memory mode selection (C101), the result of up/down processing can be stored in memory.
- If the inverter power is turned on or the RS terminal turned off with the AHD terminal left turned on, the data held immediately
before power-on or turning off the RS terminal will be used.
Item
Terminal [1] to [8] functions
AHD terminal
Input analog command
Frequency command
4.2.57 Intelligent pulse counter (PCNT and PCC)
- The intelligent pulse counter function allows you to input a pulse
train via an intelligent input terminal.
- The cumulative count of input pulses can be monitored by the pulse counter monitor (d028) function.
- The value of cumulative counter cannot be stored. The counter value is cleared to zero when the inverter power is turned on or
the inverter reset.
- Turning on the PCC (pulse counter clear)terminal clears the cumulative counter.
- The frequency resolution of the input pulse can be calculated by the formula shown below (for pulse signal input with a duty ratio
of 50%). Frequencies not less than the relevant resolution cannot be input. It is recommended to use this function up to 100Hz. For
the input terminal response, see Section 4.2.79.
Frequency resolution (Hz) = 250/(input terminal response time setting [C160 to C168] + 1)
Example: When the input terminal response time is 1, the frequency resolution is 125 Hz.
Input pulse
ON
PCNT
OFF
Value of counter
10
(%)
(Set value of KPP)
Speed error at rated torque (X)
Synchronous rotation speed at base frequency
Function code
C001 to C008
ON
Input terminal response time
1
2
4-59
Explanation of Functions
P control mode
Torque
100%
0
100%
Related code
C001 to C008: Terminal [1] to [8] functions
C101 : UP/DWN holding function
Data
65
AHD: Analog command holding
Remark)
Set frequency remains when inverter is
switched with SET/SET3 terminal with
AHD on. Turn AHD terminal off to
re-hold the set frequency.
Remark )
Frequent use of this function may
damage the memory element.
Related code
C001 to C008: Terminal [1] to terminal [8] functions
d028: Pulse counter monitor
3
PI control mode
(X)
Rotation speed
Description
4
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