Transitioning to sustainable energy in motion control
Published on : Friday 15-09-2023
Rising energy costs are causing many companies to get creative in order to optimise their products and production processes.
Energy efficiency and sustainability are not just tending topics, they are important factors for a green future – B&R is aiming for carbon neutrality by 2030. Against this background, Wilfried Guerry, global product manager for drive technology, talks in an interview about how B&R gets the maximum energy efficiency out of its servo motors and servo drives.
What influence do electric motors have on the energy efficiency of machines?
Even though they are more efficient than pneumatic or hydraulic actuators, electric motors are among the largest energy consumers in machines after air compressors and furnaces. This is a significant factor in times of sharply rising energy costs. When speaking of motors as energy consumers, undesirable phenomena include eddy current losses, Joule losses and reactive current consumption.
How much of the electrical power used is lost?
Reactive energy, which cannot be converted into mechanical energy, accounts for more than 15% of the electricity consumed by machines. B&R integrates active power supplies with power factor correction (PFC) into its ACOPOSmulti drives, which virtually eliminates the reactive component of the electrical power consumed. In addition, unlike passive variants, they also allow energy to be fed back into the power grid during regenerative braking. As a result, braking resistors no longer need to be installed in order to dissipate excess energy, which leads to more compact machines. B&R has relied on this proven solution for more than 15 years. Just by switching from passive to active power supplies, customers can lower their electricity costs and reduce their carbon footprint.
Where is B&R heading in terms of energy efficiency?
To further reduce the energy consumption of machines, it is necessary to have a complete recording of the actual energy consumed. While there are solutions for monitoring energy consumption, they don't provide information about how much energy each individual servo drive consumes and when peaks occur during the machine cycle. With a new energy monitoring function that will be integrated into B&R servo drives in the near future, operators will always know how much energy each servo drive in the machine is using. We will also soon be offering features for planned maintenance tasks. Detecting unusual current consumption on an inverter can help identify and locate an imminent mechanical problem early on.
What about switching or eddy current losses?
Servo drives from B&R can automatically reduce the switching frequency of their power transistors based on the motor speed. This can reduce electrical losses by up to 30% at low motor speeds or at a standstill. The high torque density motors offered by B&R minimize eddy current losses and deliver around 50% more torque compared to standard motors. This value clearly shows the high energy savings potential of B&R's complete motion control solution compared to the competition.
Has the mains-side supply also been reconsidered?
As effective as these measures are on the motor side, by themselves they are not enough. To achieve maximum energy efficiency of the power transmission system, we have also redesigned the mains-side supply. A new approach was necessary here: The hybrid solution developed by B&R combines the advantages of IGBT and MOSFET technology and almost completely eliminates high-loss components such as regenerative chokes and line filters. We have already been able to successfully test this patented solution in the laboratory and on pilot customers' machines. It enables energy efficiency of almost 99% with a nominal power output of 32 kW.
Do customers benefit from space savings?
The improvements increase the efficiency of the motors, and also eliminate the need for external components. For our customers, this means a space saving of almost 70% compared to existing solutions, an impressive value seen together with the increased energy efficiency.
Thank you for taking the time for this interview.
Explanation of abbreviations and functionality
• PFC – Power Factor Correction: Power factor correction filter. A technique used to minimize the reactive energy.
• IGBT – Insulated-Gate Bipolar Transistor: Bipolar transistor with insulated gate electrode. Used to achieve higher efficiency and energy savings.
• MOSFET – Metal Oxide Semiconductor Field-Effect Transistors. Allows the current flow to vary by several orders of magnitude in inverters, for example.
B&R's energy efficient motors have enabled it to become one of the very few suppliers to certify its entire motor portfolio as Class 1 of the China Energy Label (CEL). CEL certification is essential for OEMs who wish to sell their machines in China. In addition, this certification makes it easier for users worldwide to compare the energy efficiency of different devices.
“We have already been able to successfully test our patented mains-side supply solution in the laboratory and with pilot customers: It enables energy efficiency of nearly 99% with a nominal power of 32 kW,” says Wilfried Guerry.