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DC Braking (DB) Settings

Normal DC braking performanceThe DC

braking feature can provide additional stopping torque when compared to a normal deceleration to a stop. DC braking is particularly useful at low speeds when normal deceleration torque is minimal. When you enable DC braking, the inverter injects a DC voltage into the motor windings during deceleration below a frequency you can specify (A052).

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Running

 

Free run

DC brake

 

0

 

 

 

 

 

 

 

 

 

 

 

t

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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A053

 

 

 

 

A055

 

Configuring Drive Parameters

The braking power (A054) and duration (A055) can both be set. You can optionally specify a wait time before DC braking (A053), during which the motor will free run.

DC Braking – Frequency DetectionAll above operations are done when the RUN command (FW signal) turns OFF. But you can even set DC braking during Run by setting frequency detection at A051. In this case the DC brake operates when the output frequency comes down to the one you specified (A052) even the Run command is active.

External DB and Internal DC are invalid during the frequency detection mode.

FW

ON

F-SET

A052

F-OUT

DB

Ex.1) Step change in F-SET.

FW

ON

F-SET

A052

F-OUT

DB DBDB

Ex.2) Analog change in F-SET.

Example 1, above to the left shows the performance when giving the pulsing frequency set point. In this case, when changing set point to 0, inverter immediately starts DB because the set point becomes lower than the value specified in A052. And the DB continues until the set point exceeds A052. And there will be no DC braking at next stop because the FW is being OFF.

Example 2, above to the right shows the gradual change in frequency set point, for example by analog input. In this case, there will be a DC braking period at start because the frequency set point is lower than the value specified in A052.

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Hitachi X200 Series instruction manual DC Braking DB Settings, Normal DC braking performance⎯ The DC