Driving With V/F Control With Encoder - Hitachi WJ Series User Manual

Chapter 9
9.5.5

Driving with V/f Control with Encoder

 How to use speed feedback from the motor to apply V/f control with a high degree of rotational
Q
accuracy?
 How to closely control fan and pump rotational output based on their speed characteristics?
 How to accurately make motor rotation follow the frequency command in order to calculate the
number of turns?
 The V/f control with encoder function is a function that uses an encoder to provide feedback of
A
the motor's actual speed for highly accurate frequency control.
 This function controls the motor by correcting PI control so that the number of motor rotations
follows the frequency command.
 The V/f control with encoder function is unavailable when "2nd-motor control [SET]" is ON. This
function is only available when using the first control mode
 To set "90 degrees shift pulse (01)" or "Forward and reverse command and pulse (03)" for "Pulse
input mode selection [P004]", set "Input terminal [7] function [C007]" to "Pulse input B [PLB]
(85)". [PLB] can only be assigned to input terminal [7], and the active state (NO/NC) settings will
also be disabled.
 For details on encoders, refer to "9.5.8 Using Encoder Feedback".
Deviation ε
Command
+
frequency
Code Item
[A044] Control mode selection
Pulse input, target function
[P003]
selection
[P004] Pulse input mode selection
[P011] Encoder constant
[P012] Simple positioning selection
[P026] Over-speed detection level
Speed deviation error
[P027]
detection level
Speed detection filter
[P901]
constant for encoder pulse
Slip compensation P-gain
[H050]
at V/f with encoder
Slip compensation I-gain at
[H051]
V/f with encoder
[C007] Input terminal [7] function
[C021]
[C022] Output terminal function
[C026]
PI control
1
�� (1 + )
��
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-
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Kp: Proportional gain setting, Ti: Integral time, s: Operator, ε: Deviation
Ki: Integral gain setting (Ki=Kp/Ti)
V/f control with encoder is only available when
using V/f control of first control mode.
Speed feedback
Single-phase pulse input
90° phase difference pulse input
Forward/reverse rotation command and pulse input
Sets the number of pulses per encoder revolution.
Simple position control disabled
If [P003] is 01 and [P026] is a value other than 0.0, an
"Over-speed error [E81]" trip will occur when the
"Detect speed monitor [d008]" equals or exceeds the
{Maximum frequency × [P026]} during operation.
Sets the excessive speed deviation level when an
"Speed over deviation [DSE]" is assigned to "Output
terminal function ([C021] to [C026])".
Filter time constant for the detected speed by
encoder pulse input.
Proportional (P) gain for slip compensation when
using V/f control with encoder.
Integral (I) gain for slip compensation when using
V/f control with encoder. Set using integral time.
Pulse input B [PLB]:
The [PLB] terminal is the input terminal for the
direction signal or phase B pulse input during
encoder feedback.
Speed over deviation [DSE]:
The [DSE] signal turns on when the following
conditions are met during operation.
.
Control
Frequency
+
frequency
voltage
+
control
Feedback
Description
| [d001] - [d008] | ≧ [P027]
9-5-8
Inverter Functions
Encoder
M
Data
00 to 02
01
00
01
03
32 to 1024
00
0.0 to 150.0 (%)
0.00 to 120.00 (Hz)
0 to 9999 (ms)
0.00 to 10.00
0 to 1000 (s)
85
22