Kinetic Buffer

A Kinetic Buffer (KB) axis is used to store energy mechanically in a rotating disc, also known as a Flywheel. This energy can be used in a mains power loss to feed the DC bus with energy for a machine to finish its cycle and come to a controlled stop. During a mains power loss, the KB can also be used to absorb energy in a rapid braking event.

Enable the KB feature in the Rotary mechanism form. When the KB feature is enabled, the axis sequence is a locked down and cannot be changed in the Sequence form unless the KB feature is turned off.

In Normal mode, the KB maintains its Constant Velocity [Const Vel].

In Backup Power mode, during the mains power loss, the KB is engaged to maintain the DC bus within KB_V0 and KB_V1. If the KB velocity drops below its Minimum Velocity [Min Vel], or rises above its Maximum Velocity [Max Vel], then a System Check warning message occurs. The Min Vel Is used as a warning, as the KB can still drop to 0. However, the Max Vel is the maximum allowed, such that when adding energy to the flywheel, the KB absorbs energy up to its MaxVel. And when MaxVel is reached, then the regen energy will accumulate on the DC bus and then eventually overflow to the Bleeder. When the power loss ends, the Recovery ramp is used to ramp the KB to its Const Vel.

When in Max-Stop mode, the KB maintains its Constant Velocity. The KB is assumed to be in its own protected cage and always runs at its set speed until a power loss triggers it to be used for backup power management.

In Master Follower applications, when in Normal Operating Mode, the KB axis maintains its Constant Velocity regardless of any changes to the Master.

The only time the KB velocity changes from is in Backup Power Mode during the loss of mains supply power.

Maximum Power Samples

When a KB is in a power group, then the maximum number of power samples is limited to 10,000, which is the maximum allowed sequence segments.

Voltage Levels: KB Only

For proper KB operation, set the voltage levels per the following.

KB_V0 <= Vz0 <= KB_V1 <= Vz1

Typical values:

KB_V1 = 0.95 * Vz1

KB_V0 = 0.95 * Vz0

Voltage Levels: KB + ESM

While it is possible to use both a Kinertic Buffer and Energy Storage Modules on the same DC bus, it is not common. If using both on the same DC bus, check with the vendor to ensure both features are supported together, and pay special attention to the voltage levels to meet the following requirements.

KB_V0 < ESM_V0 < Vz0 < ESM_V1 < KB_V1 <= Vz1

Each voltage level should be separated by a voltage gap.
Check with the drive vendor.

Symbol	Description	Units
KB_V1	Kinetic Buffer DC Bus Voltage Upper KB starts motoring to remove energy from the DC bus	Vdc
KB_V0	Kinetic Buffer DC Bus Voltage Lower KB starts generating to feed energy to the DC bus	Vdc
Vz1	DC Bus Threshold Voltage Chopper starts feeding excess energy to the bleeder	Vdc
Vz0	DC Bus Nominal Voltage Infeed/Drive normal operating DC bus voltage	Vdc
ESM_V1	Energy Storage Module DC Bus Voltage Upper ESM starts storing excess energy from the DC bus	Vdc
ESM_V0	Energy Storage Module DC Bus Voltage Lower ESM starts feeding energy to the DC bus	Vdc

Kinetic Buffer

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