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Yaskawa E7 Drive Technical Manual User Manual

Page 21

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Date: 02/25/2010, Rev: 10-02

Page 21 of 34

TM.F7SW.064

5.0 Function Description

5.1 Basic Electronic Lineshaft

When the Follower Mode Selection P1-01 = 1 ~ 3 (speed follower mode), the follower drive will follow the

speed of the master encoder signal. Using the gear ratio parameters P1-03 ~ P1-06, the follower drive

can be made to run at a ratio of the master speed. The alternate gear ratio (P1-07 & P1-08) can be

selected using the Ratio 2 Select multi-function digital input (H1-0X = 81). The basic gear ratio formula is:

Follower Frequency Reference = Master Encoder Frequency Reference x (Numerator / Denominator)

For the primary gear ratio, the formula is:

Master

Encoder

Frequency

Reference

(U1-90)

X

X X X X X X X X
X X X X X X X X

=

Follower

Frequency

Reference

(U1-91)

P1-03

P1-04

P1-05

P1-06

The pairs of numerator and denominator parameters are used together to form an 8-digit number divided

by an 8-digit number. For ratio’s that can be expressed using 4-digit numbers or less, simply use P1-

03/P1-04. Gear ratio 2 can only be expressed as a 4-digit number divided by a 4-digit number.

The gear ratio needed for the application must be able to be exactly expressed by the above formula.

This includes the complete remainder. If the ratio cannot be exactly expressed, the follower will drift in

phase over time.

The gear ratio can be further adjusted using the Digital Ratio Adjustment P2-01), the Analog Ratio

Adjustment (H3-05/09 = 20), the MOP Adjust multi-function inputs (H1-0X = 84 ~ 86), and the Network

Communication Ratio Adjustment (Modbus register 61CH). These adjustments are summed and then

added to 100% to produce the total gear ratio adjustment, which is multiplied by the master encoder

frequency (after gear ratio calculation). See Figure 8 at the end of the document.

When Follower Mode Selection P1-01 = 4 or 5 (ELS modes), the drive will track follower position relative

to the master encoder. A PI regulator is applied to the position error. The output of the position PI

regulator is used to trim the speed reference calculated from the master encoder signal, gear ratio

parameters, and gear ratio adjustment. In this manner, the position of the follower motor will be

synchronized with the position of the master encoder. The Advance Follower (H1-0X = 82) and Retard

Follower (H1-0X = 83) multi-function inputs can be used to change the position of the follower relative to

the master. See Figure 7 at the end of the document.

When the gear ratio of the drive is changed instantaneously in ELS mode (either due to the gear ratio

parameters being changed during run or because of a change of state of the Ratio 2 Select multi-function

input), the drive will ramp to the new ratio using Accel/Decel Time 2 (C1-03/C1-04). The position error will

be held to zero during the ratio change until the drive re-enters Speed Agree (based on the Ratio Change

Speed Agree Width P3-07).

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