Slip Compensation; Encoder Feedback Control - Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual

• When the inverter protective function (E.OC[], E.THT) is activated due to increased magnetic excitation deceleration,
adjust the level set in Pr.662.
• The overcurrent preventive function is disabled when Pr.662 = "0".
NOTE
• When the level set in Pr.662 is more than the one set in Pr.22 Stall prevention operation level, the overcurrent preventive
function is activated at the level set in Pr.22. (The level set in Pr.662 is applied when Pr.22 = "0".)
Parameters referred to
Pr.22 Stall prevention operation
Pr.30 Regenerative function
Pr.60 Energy saving control
Pr.162 Automatic restart after instantaneous power failure
Pr.270 Stop-on contact/load torque high- speed frequency control
Pr.261 Power failure stop
Pr.350 Stop position command

5.16.14 Slip compensation

V/F V/F V/F
Under V/F control, the slip of the motor is estimated from the inverter output current to maintain the rotation of the motor
constant.
Pr.
245
Rated slip
G203
246 Slip compensation time
G204 constant
247 Constant output range slip
G205 compensation selection
• Calculate the rated motor slip and set the value in Pr.245 to enable slip compensation.
Slip compensation is not performed when Pr.245 = "0 or 9999".
Synchronized speed at the time of base frequency - rated rotation speed
Rated slip =
NOTE
• When the slip compensation is performed, the output frequency may become larger than the set frequency. Set Pr.1 Maximum
frequency higher than the set frequency.
• Slip compensation will be disabled in the following conditions:
Stall prevention (oL, OL) operation, regeneration avoidance operation, auto tuning, encoder feedback control operation
Parameters referred to
Pr.1 Maximum frequencypage 407
Pr.3 Base frequencypage 673

5.16.15 Encoder feedback control

Magnetic flux Magnetic flux Magnetic flux
V/F V/F V/F
This controls the inverter output frequency so that the motor speed is constant to the load variation by detecting the motor
speed with the speed detector (encoder) to feed back to the inverter.
A Vector control compatible option is required.
700
5. PARAMETERS
5.16 (G) Control parameters
levelpage 409
selectionpage 689
selectionpage 678
selectionpage 610
selectionpage 554
Name Initial value
9999
0.5 s
9999
Synchronized speed at the time of base frequency
selectionpage 597, page 604
selectionpage 546
Setting
range
0.01 to 50% Set the rated motor slip.
0, 9999 No slip compensation
Set the response time of the slip compensation. Reducing the
0.01 to 10 s value improves the response, but the regenerative overvoltage
(E.OV[]) error is more likely to occur with a larger load inertia.
No slip compensation in the constant power range (frequency
0
range higher than the frequency set in Pr.3).
9999 Slip compensation is performed in the constant power range.
Description
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