1) Introduction
The Koch Bremsenergie (Koch Brake Energy) module is an energy management module which provides several advantages and safety features to your drive.
Advantages for Energy Management
Manage braking energy
Smoothing of DC bus voltage (in here from now on called DC link voltage)
Increasing energy efficiency (up to 25%)
Enhancing productivity (up to 50%)
Compensation for voltage dips
Bridging power failures
Controlled stops in case of power outage
Reducing peak loads on the power grid
Safety Features
Reverse polarity protection for intermediate circuit
Integrated pre-charging
Charging protection switch
Integrated load monitoring on both sides
Internal fuses
Extensions
Plug-On module PxtMX for current-based load-reduction and fieldbus connection (EtherCAT)
2) Lay Out and Sizing
The layout and sizing can be done in cooperation with Koch Bremsenergie (Contact Information).
In order to find the best solution, it will be beneficial to provide some data depending on the use case.
Furthermore, the layout-portal can be used to gather some initial information.
Here is a detailed list of which data one should prepare:
In General
Limit current / power from grid
Grid topology (voltage, phase number, frequency)
Energy of load peaks / load cycle
Infeed rectifier (XCS, XVE) / active front end (XVR)
Intermediate circuit capacity
Connection cable length (Converter and PxtFX / PxtRX)
Recuperation
Max. braking power
Braking time
Braking power curve over time (block / ramp)
Cycle time
Load peak reduction
Average power demand
Max. power demand and peak load
Duration of load peak
Load peak curve over time
Cycle time of load peak
Short-term UPS (uninterruptible power supply) (German: USV)
Max. power demand
Support time ("Stütz-Zeit")
Power demand curve over time (block / ramp)
Cycle time
You can use several options to generate a power-time-diagram:
Oscilloscope App (probably lowest effort)
IndraSize
Servosoft
Use InfluxDB to store your data (Getting started with InfluxDB on ctrlX CORE)
You will need to use NodeRED or Telegraf to contribute data to InfluxDB
In general, a power-time-diagram will be sufficient. (Mains Power: P-0-0382.0.0)
3) Connection
The Koch Module has several different connections that will be shown in the following diagram:
Further technical details are available on the product webpage.
The connection itself is quite simple.
One can easily connect the Koch Module to the intermediate circuit of the drive. There is no further configuration needed.
In the following image, which is taken in Ulm, one Koch-Module (red) and two Supercaps (black) are visible:
4) Control Strategy
Short-term UPS - Functionality
The Koch Module is used to protect the application against short-term grid power faults. Define an UPS voltage level (e.g. 470 VDC) which the company Koch will parametrize inside the module.
If the voltage is above 470 VDC, the drive system will be fed by the power from the grid. In case of power interruption, the DC-bus voltage decreases. If the voltage would go below 470 VDC, the Koch Module will power up the DC-bus and stabilize the voltage level as long as energy is available. The Koch Module will start to recharge itself when a defined DC-bus voltage is reached.
Manage Braking Power
The Koch module can be efficiently used to manage braking power. The braking power of a drive, which normally would dissipate into heat and be wasted, can be saved by an energy storage system.
The Koch Module provides two working principles:
a) Set a fixed DC-bus voltage level (e.g. 730 VDC) to activate and deactivate the Koch Module
When the DC-bus voltage exceeds 730 VDC, the Koch module starts to take energy out of the DC-bus with a current/voltage-ramp of 1 A/V.
If the Koch Module's power is not enough, and the DC-bus power is still increasing, the Koch Module increases the current with 1 A/V. (E.g. 735V = 5V difference -> 5A).
When the voltage decreases and gets below 730 VDC, the Koch Module will be discharged and stabilize the DC-bus voltage with a current/voltage-ramp of 1 A/V.
b) The Koch Module is triggered by brake off chopper-signal
The Koch Module will be triggered by BRC signal (brake chopper off signal) in this case. It will be in teaching mode and automatically set the DC-bus voltage level to 40 VDC below the chopper-off-voltage-level. Activation and Deactivation of the Module will behave exactly like in case a).
Example: Chopper off voltage level = 770 VDC -> After some cycles, the Koch Module will be activated by 730 VDC with storage current per DC Bus voltage difference of 1 A/V (PxtFX).
-> In this mode, the Koch Module will set the DC-Bus voltage level to max. 760 VDC.
Peak power shaving with active front end power supply XVR
The use of active front-end inverters enhances functionality. XVR offers features such as infeed current limitation (power limitation) and regenerative current limitation. Hence, the Koch Module can provide peak power shaving functionality.
Example: The application needs 160kW peak power on DC-bus and the connected Koch Module can provide 40kW peak which reduces the necessary power supply to 120kW. In result, the infeed current can be limited to 173A (120kW at a three-phase 400 VAC supply).
The same procedure is possible for regenerative power to the grid.
Power control with Koch PxtMX communication module
Using the Koch PxtMX communication module, the system can be controlled via EtherCAT, enabling cyclic command value control of the Koch Modules. This will provide more flexibility in power and energy control.
For more details on technical data, visit the company website or reach out directly to a Koch team member.
5) Exemplary Topology
