What is a DC Link Connection?

A DC link connection connects the DC links of multiple servo inverters to form a common network. When one axle brakes, its motor feeds the braking energy into this shared intermediate circuit, from which another axle that is accelerating immediately draws on it. The energy is thus reused instead of being converted into heat in the braking resistor, which reduces power consumption from the grid.

For Which Machines is a DC Link Connection Worthwhile?

A DC link connection is beneficial for any machine whose servo axes brake and accelerate out of sync, because only then can the braking energy from one axis be fed to the other. Typical applications for a DC link connection include twin-shaft shredders, screw presses and plastics and packaging machinery.

Can I reduce the number of braking resistors by using a DC link connection?

Yes, the number of braking resistors can be reduced. Since the braking energy is distributed among the axles, less energy needs to be dissipated through the braking resistor. The braking resistor can be sized smaller or eliminated entirely, which saves space in the control cabinet and reduces costs. The brake chopper remains in the device as the control circuit; The external ballast resistor is only installed when needed.

Does a DC Link Connection Help During Load Peaks and Power Outages?

A DC link connection is effective in two situations. It reduces peak loads because some of the energy required for acceleration comes from recovered braking energy rather than from the grid. And the energy stored in the intermediate circuit serves as a buffer: In the event of a power failure, the axes move in a controlled manner to a defined position, depending on the remaining energy. This protects the mechanical components and can eliminate the need for a separate, independent power supply.

How are the servo inverters connected to a DC link connection?

Connecting to a DC link connection is simple: For single-unit systems with integrated DC bus capacitors, such as the b maXX 5500 and 6500, all you need to do is connect two units in the control cabinet using two cables. For larger or mixed setups, the Drive Connect System handles the daisy-chain configuration, and an intermediate circuit coupling module connects wired devices to devices on a shared copper bus bar in accordance with industry standards.

Do I Need a Separate Feed-In or Feed-Back Module?

A separate module is not required. In a DC link connection, power fed back into the grid is minimized or eliminated, so no additional power-feedback unit is required. A high-performance single unit can also serve as the power supply for the axis group, eliminating the need for a separate power supply. Where there is a persistent surplus of braking energy that needs to be fed back into the grid, Baumüller offers the b maXX 5100 series of energy recovery and feed-back units with sinusoidal grid feed-back in a power range of 36 to 200 kW of DC link power.

How is the Intermediate Circuit Protected Against Overvoltage?

Excess braking energy causes the DC link voltage to rise. Traditionally, the energy is converted into heat via a braking resistor to protect the drive from overvoltage. In a DC link connection, this energy is instead transferred to other drives or fed back into the grid via a regenerative feed-in system. This stabilizes the DC link and reduces the load on the braking resistor.

How is the Intermediate Circuit Protected and Designed?

In a DC link connection, an optional integrated DC link fuse replaces the external fuse. The charging circuit in the servo converter can be configured as a thyristor-based charging circuit or a resistive charging circuit. With thyristor-controlled power injection, the grid reactor may not be necessary, depending on the application. The specific sizing, i.e. fuse ratings as well as pre-load and protection configurations, is specific to each device and system and is defined in the project planning manual.

Can a DC Link Connection be Retrofitted or Combined with Older Model Series?

A DC link connection can be easily retrofitted: Devices with built-in intermediate circuit capacities are connected inside the control cabinet. The transition to the new generation is seamless; The firmware of the b maXX 6000 series is fully compatible with that of its predecessor, the b maXX 5000 series. The switch can be made without any new programming or parameterization. Baumüller evaluates on a case-by-case basis whether or not specific older servo controllers can be connected and how balancing currents and fuses should be configured in such cases.

Is a DC link connection worth it?

A DC link connection offers three benefits: reduced energy consumption from the grid, smaller or eliminated braking resistors, resulting in a smaller control cabinet and a lower load on the grid. The amount of the savings depends on the machine's load profile, i.e. how often and how intensely the axes brake and accelerate in a staggered manner. Baumüller calculates specific savings potential based on the specific application.

What is a DC Link Connection?

A DC link connection connects the DC links of multiple servo inverters to form a common network. When one axle brakes, its motor feeds the braking energy into this shared intermediate circuit, from which another axle that is accelerating immediately draws on it. The energy is thus reused instead of being converted into heat in the braking resistor, which reduces power consumption from the grid.

For Which Machines is a DC Link Connection Worthwhile?

A DC link connection is beneficial for any machine whose servo axes brake and accelerate out of sync, because only then can the braking energy from one axis be fed to the other. Typical applications for a DC link connection include twin-shaft shredders, screw presses and plastics and packaging machinery.

Can I reduce the number of braking resistors by using a DC link connection?

Yes, the number of braking resistors can be reduced. Since the braking energy is distributed among the axles, less energy needs to be dissipated through the braking resistor. The braking resistor can be sized smaller or eliminated entirely, which saves space in the control cabinet and reduces costs. The brake chopper remains in the device as the control circuit; The external ballast resistor is only installed when needed.

Does a DC Link Connection Help During Load Peaks and Power Outages?

A DC link connection is effective in two situations. It reduces peak loads because some of the energy required for acceleration comes from recovered braking energy rather than from the grid. And the energy stored in the intermediate circuit serves as a buffer: In the event of a power failure, the axes move in a controlled manner to a defined position, depending on the remaining energy. This protects the mechanical components and can eliminate the need for a separate, independent power supply.

How are the servo inverters connected to a DC link connection?

Connecting to a DC link connection is simple: For single-unit systems with integrated DC bus capacitors, such as the b maXX 5500 and 6500, all you need to do is connect two units in the control cabinet using two cables. For larger or mixed setups, the Drive Connect System handles the daisy-chain configuration, and an intermediate circuit coupling module connects wired devices to devices on a shared copper bus bar in accordance with industry standards.

Do I Need a Separate Feed-In or Feed-Back Module?

A separate module is not required. In a DC link connection, power fed back into the grid is minimized or eliminated, so no additional power-feedback unit is required. A high-performance single unit can also serve as the power supply for the axis group, eliminating the need for a separate power supply. Where there is a persistent surplus of braking energy that needs to be fed back into the grid, Baumüller offers the b maXX 5100 series of energy recovery and feed-back units with sinusoidal grid feed-back in a power range of 36 to 200 kW of DC link power.

How is the Intermediate Circuit Protected Against Overvoltage?

Excess braking energy causes the DC link voltage to rise. Traditionally, the energy is converted into heat via a braking resistor to protect the drive from overvoltage. In a DC link connection, this energy is instead transferred to other drives or fed back into the grid via a regenerative feed-in system. This stabilizes the DC link and reduces the load on the braking resistor.

How is the Intermediate Circuit Protected and Designed?

In a DC link connection, an optional integrated DC link fuse replaces the external fuse. The charging circuit in the servo converter can be configured as a thyristor-based charging circuit or a resistive charging circuit. With thyristor-controlled power injection, the grid reactor may not be necessary, depending on the application. The specific sizing, i.e. fuse ratings as well as pre-load and protection configurations, is specific to each device and system and is defined in the project planning manual.

Can a DC Link Connection be Retrofitted or Combined with Older Model Series?

A DC link connection can be easily retrofitted: Devices with built-in intermediate circuit capacities are connected inside the control cabinet. The transition to the new generation is seamless; The firmware of the b maXX 6000 series is fully compatible with that of its predecessor, the b maXX 5000 series. The switch can be made without any new programming or parameterization. Baumüller evaluates on a case-by-case basis whether or not specific older servo controllers can be connected and how balancing currents and fuses should be configured in such cases.

Is a DC link connection worth it?

A DC link connection offers three benefits: reduced energy consumption from the grid, smaller or eliminated braking resistors, resulting in a smaller control cabinet and a lower load on the grid. The amount of the savings depends on the machine's load profile, i.e. how often and how intensely the axes brake and accelerate in a staggered manner. Baumüller calculates specific savings potential based on the specific application.

DC Link Connection: Harnessing Braking Energy and Saving Energy

Baumüller has increased its focus on the development of energy-efficient drive concepts for many years. The efficient use of resources is also evident in the b maXX servo drives, which can be connected to each other via a common DC link. For example, during braking, the system’s kinetic energy can be converted into electrical energy and distributed to other axes by the DC link system.

Saving Energy with a Two-Shaft Shredder

In a two-shaft shredder, the regenerated braking energy from the first shredder shaft can be used to drive the second shaft. This principle works in both normal operation and reverse operation. To save even more energy and reduce costs, one shredder shaft can accelerate as soon as the other slows down.

How a DC link connection works

Energy efficiency through temporary storage

When a motor decelerates, energy is fed back into the servo drive’s DC link. The DC link connection thus transfers the regenerative braking energy of the motor as motor energy for another servo drive. This means that overall, less energy is required from the power grid.

Temporary store saves brake resistors

To protect the servo drive from overvoltage, a braking resistor converts the surplus energy into heat. The energy is "burned" in the process. A DC link system allows surplus energy to be divided between two or more b maXX servo drives. This means that brake resistors can be designed smaller or omitted entirely. This saves space and reduces costs for the control cabinet and energy.

Energy buffer for controlled shutdown of the system

The DC link system also impresses in the event of malfunctions. In the event of a power outage or malfunction, the stored energy can be used to shut down the system in a controlled manner. The drive axles can thus be moved to a defined position depending on the available residual energy and the energy requirement. This prevents damage and accelerates a machine restart considerably. This function is integrated directly into the drive and can immediately execute this response in the event of a fault, e.g., to prevent damage to the mechanics.
In addition to increasing system availability, the energy buffer can also remove the need for an independent power supply.

How can servo drives be connected to a DC link system?

Implementing a DC link connection is very simple. Since the mono units of the b maXX 5500 and b maXX 6500 series are equipped with integrated DC link capacitors as standard, the two devices for two drives, for example, only need to be connected in the control cabinet with two cables.

What are the advantages of a DC link connection?

Energy exchange between drives: In a DC link system, drives that brake can feed energy back into the DC link. This braking energy can be used by other drives that are accelerating. This significantly improves the efficiency of the overall system, as less energy is drawn from the power supply, and less energy is wasted as heat.
Reduction in energy consumption: The external energy requirement can be reduced by reusing braking energy. This leads to lower operating costs and a better energy balance.
Hardware cost savings: Since brake resistors can be designed smaller or eliminated entirely, control cabinets can be made smaller. This reduces the cost of the required hardware.
Greater system availability: Thanks to energy buffers, the machine can often be shut down in a controlled manner in the event of a malfunction, meaning that it is ready for use again more quickly.
Lower network load: Energy exchange via the DC link reduces power supply demand.
Reduction of energy & costs as well as CO₂ footprint.

Saving Energy Beyond the Shredder

The twin-shaft shredder illustrates the principle particularly clearly, but it is not limited to that. A DC link connection is beneficial anywhere where multiple servo axes brake and accelerate at different times, for example in screw presses, plastic processing machines or packaging systems. The page on the fully electric high-torque drive solution for shredders shows how Baumüller designs the complete drive system for shredders. The technical fundamentals of this topic are explored in greater depth in the introductory article on the intermediate circuit.

Are you interested in buying our products?

Write us a message, our sales experts will be happy to advise you.

Contact sales now

FAQ
Frequently Asked Questions About Baumüller’s DC Link Connection

Do you have any questions about our DC bus system? You can find answers here. Our FAQs provide initial assistance. Please send us a message if you require further information.

What is a DC Link Connection?

A DC link connection connects the DC links of multiple servo inverters to form a common network. When one axle brakes, its motor feeds the braking energy into this shared intermediate circuit, from which another axle that is accelerating immediately draws on it. The energy is thus reused instead of being converted into heat in the braking resistor, which reduces power consumption from the grid.
For Which Machines is a DC Link Connection Worthwhile?

A DC link connection is beneficial for any machine whose servo axes brake and accelerate out of sync, because only then can the braking energy from one axis be fed to the other. Typical applications for a DC link connection include twin-shaft shredders, screw presses and plastics and packaging machinery.
Can I reduce the number of braking resistors by using a DC link connection?

Yes, the number of braking resistors can be reduced. Since the braking energy is distributed among the axles, less energy needs to be dissipated through the braking resistor. The braking resistor can be sized smaller or eliminated entirely, which saves space in the control cabinet and reduces costs. The brake chopper remains in the device as the control circuit; The external ballast resistor is only installed when needed.
Does a DC Link Connection Help During Load Peaks and Power Outages?

A DC link connection is effective in two situations. It reduces peak loads because some of the energy required for acceleration comes from recovered braking energy rather than from the grid. And the energy stored in the intermediate circuit serves as a buffer: In the event of a power failure, the axes move in a controlled manner to a defined position, depending on the remaining energy. This protects the mechanical components and can eliminate the need for a separate, independent power supply.
How are the servo inverters connected to a DC link connection?

Connecting to a DC link connection is simple: For single-unit systems with integrated DC bus capacitors, such as the b maXX 5500 and 6500, all you need to do is connect two units in the control cabinet using two cables. For larger or mixed setups, the Drive Connect System handles the daisy-chain configuration, and an intermediate circuit coupling module connects wired devices to devices on a shared copper bus bar in accordance with industry standards.
Do I Need a Separate Feed-In or Feed-Back Module?

A separate module is not required. In a DC link connection, power fed back into the grid is minimized or eliminated, so no additional power-feedback unit is required. A high-performance single unit can also serve as the power supply for the axis group, eliminating the need for a separate power supply. Where there is a persistent surplus of braking energy that needs to be fed back into the grid, Baumüller offers the b maXX 5100 series of energy recovery and feed-back units with sinusoidal grid feed-back in a power range of 36 to 200 kW of DC link power.
How is the Intermediate Circuit Protected Against Overvoltage?

Excess braking energy causes the DC link voltage to rise. Traditionally, the energy is converted into heat via a braking resistor to protect the drive from overvoltage. In a DC link connection, this energy is instead transferred to other drives or fed back into the grid via a regenerative feed-in system. This stabilizes the DC link and reduces the load on the braking resistor.
How is the Intermediate Circuit Protected and Designed?

In a DC link connection, an optional integrated DC link fuse replaces the external fuse. The charging circuit in the servo converter can be configured as a thyristor-based charging circuit or a resistive charging circuit. With thyristor-controlled power injection, the grid reactor may not be necessary, depending on the application. The specific sizing, i.e. fuse ratings as well as pre-load and protection configurations, is specific to each device and system and is defined in the project planning manual.
Can a DC Link Connection be Retrofitted or Combined with Older Model Series?

A DC link connection can be easily retrofitted: Devices with built-in intermediate circuit capacities are connected inside the control cabinet. The transition to the new generation is seamless; The firmware of the b maXX 6000 series is fully compatible with that of its predecessor, the b maXX 5000 series. The switch can be made without any new programming or parameterization. Baumüller evaluates on a case-by-case basis whether or not specific older servo controllers can be connected and how balancing currents and fuses should be configured in such cases.
Is a DC link connection worth it?

A DC link connection offers three benefits: reduced energy consumption from the grid, smaller or eliminated braking resistors, resulting in a smaller control cabinet and a lower load on the grid. The amount of the savings depends on the machine's load profile, i.e. how often and how intensely the axes brake and accelerate in a staggered manner. Baumüller calculates specific savings potential based on the specific application.