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Overexcitation Deceleration

Overexcitation deceleration quickly decelerates motors without braking resistors.

This lets you stop a motor more quickly than with the ramp to stop processes.

Overexcitation deceleration increases excitation current during deceleration to cause a large quantity of braking torque through motor overexcitation. You can set the deceleration speed to adjust the deceleration time for overexcitation deceleration.

Overexcitation deceleration lets you accelerate the motor again during deceleration.

Enter the Run command during overexcitation deceleration to cancel overexcitation deceleration and accelerate the drive to the specified speed.

To enable this function, set L3-04 = 4, 5 [Stall Prevention during Decel = Overexcitation/High Flux, Overexcitation/High Flux 2].

When L3-04 = 4, the motor will decelerate for the deceleration time set in C1-02, C1-04, C1-06, or C1-08. If the drive detects ov [Overvoltage], increase the deceleration time.

When L3-04 = 5, the drive uses the value in C1-02, C1-04, C1-06, or C1-08 to decelerate and it adjusts the deceleration rate to keep the DC bus voltage at the level set in L3-17 [DC Bus Regulation Level]. The load inertia and motor characteristics have an effect on the braking time.

Notes on Overexcitation Deceleration

  • Do not use Overexcitation Deceleration with a braking resistor.

  • Do not use Overexcitation Deceleration for these applications. Connect a braking resistor to the drive as an alternative to Overexcitation Deceleration.

    • Frequent sudden decelerations

    • Continuous regenerative loads

    • Low inertia machines

    • Machines that have no tolerance for torque ripples

  • Motor loss increases during overexcitation deceleration. Use this function when the duty time factor is 5% ED or less and the braking time is 90 seconds or less. The load inertia and motor characteristics have an effect on the braking time. You can use overexcitation deceleration in OLV control and CLV control, but those control methods decrease the precision of torque control and braking efficiency. Use V/f control for the best results.

  • The drive disables these functions during braking with Overexcitation Deceleration 2:

    • Hunting Prevention Function (V/f Control)

    • Torque Limit Speed Control (OLV Control)