High slip braking quickly decelerates motors without braking resistors.
This lets you stop a motor more quickly than with the ramp to stop processes. This function is best for applications that do not frequently stop the motor, for example the fast stop function for high-inertia loads. Braking starts when the MFDI for High Slip Braking (HSB) Activate [H1-xx = 68] activates.
Figure 1. High Slip Braking Time Chart
An induction motor is necessary to use high slip braking. Set A1-02 = 0 [Control Method Selection = V/f Control] to enable high slip braking:
Principles of Operation
HSB increases motor slip by significantly decreasing the frequency supplied to the motor at the same time that deceleration starts. A large quantity of current flows through the motor to increase the motor loss, and the motor decelerates while the motor windings consume the regenerative energy.
The drive keeps the motor current at a constant level during deceleration to prevent overvoltage and do automatic braking and it also keeps a slip level that causes the maximum quantity of deceleration torque.
High Slip Braking Precautions
-
Do not use the high slip braking function in these applications:
-
Frequent deceleration
-
Deceleration time differences
-
Continuous regenerative loads
-
It is necessary to accelerate again during deceleration
-
Motor loss increases during high slip braking. 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.
-
The drive ignores the configured deceleration time during high slip braking. To stop motors in the configured deceleration time, set L3-04 = 4 [Stall Prevention during Decel = Overexcitation/High Flux].
-
You cannot use high slip braking to decelerate deceleration at user-defined speeds. To decelerate at user-defined speeds, use the overexcitation deceleration function.
-
You cannot accelerate the motor again during high slip braking until you fully stop the motor and input the Run command again.
-
You cannot use high slip braking and the KEB Ride-Thru function at the same time. If you enable those two functions, the drive will detect oPE03 [Multi-Function Input Setting Err].