The Speed Search function detects the actual speed of a coasting motor, then restarts the motor before the motor stops. Use Speed Search in these conditions:

  • To continue operation after momentary power loss

  • To switch from commercial power supply to drive power

  • To restart a coasting fan

For example, the drive output turns off and the motor coasts when there is a momentary loss of power. After you return power, the drive does Speed Search on the coasting motor, and restarts the motor from the detected speed.

When you use a PM motor, enable b3-01 [Speed Search at Start Selection].

There are two types of Speed Search for induction motors: Current Detection and Speed Estimation. Use parameter b3-24 [Speed Search Method Selection] to select the type of Speed Search.

Parameter settings are different for different types of Speed Search. Refer to Table 1 for more information.

Table 1. Speed Search and Related Parameters

Parameter

Speed Estimation

Current Detection 2

b3-24 = 1

b3-24 = 2

b3-01 [Speed Search at Start Selection]

x

x

b3-03 [Speed Search Deceleration Time]

-

x

b3-05 [Speed Search Delay Time]

x

x

b3-06 [Speed Estimation Current Level 1]

x

-

b3-07 [Speed Estimation Current Level 2]

x

-

b3-08 [Speed Estimation ACR P Gain]

x

-

b3-09 [Speed Estimation ACR I Time]

x

-

b3-10 [Speed Estimation Detection Gain]

x

-

b3-14 [Bi-directional Speed Search]

x

x 1

b3-17 [Speed Est Retry Current Level]

x

x

b3-18 [Speed Est Retry Detection Time]

x

x

b3-19 [Speed Search Restart Attempts]

x

x

b3-24 [Speed Search Method Selection]

x

x

b3-25 [Speed Search Wait Time]

x

x

b3-26 [Direction Determination Level]

x

-

b3-27 [Speed Search RUN/BB Priority]

x

x

b3-29 [Speed Search Back-EMF Threshold]

-

-

b3-31 [Spd Search Current Reference Lvl]

-

x

b3-32 [Spd Search Current Complete Lvl]

-

x

b3-33 [Speed Search during Uv Selection]

x

x

b3-35 [Low Back EMF Detection Level]

x

x

b3-36 [High Back EMF Detection Level]

x

x

b3-54 [Search Time]

-

-

b3-55 [Current Increment Time]

-

-

b3-56 [InverseRotationSearch WaitTime]

-

x
 
Note:

  • To use Speed Estimation Speed Search with V/f Control, do Rotational Auto-Tuning before you set the Speed Search function. If the wire length between the drive and motor changed since the last time you did Auto-Tuning, do Stationary Auto-Tuning for Line-to-Line Resistance process again.

  • If A1-02 = 5, 6 [PM Open Loop Vector, PM Advanced Open Loop Vector] and the wiring distance between the motor and drive is long or if the motor is coasting at more than or equal to 200 Hz, do not use Speed Search to restart the motor. Use Short Circuit Braking.

1

On drives with software versions PRG: 01023 and later, this function is enabled. On drives with software versions PRG: 01022 and earlier, when b3-24 = 2 [Speed Search Method Selection = Current Detection 2], setting b3-14 = 1 will not have an effect on the drive operation. The “PRG” column on the nameplate on the right side of the drive identifies the software version. You can also use U1-25 [SoftwareNumber Flash] to identify the software version.