When microseconds count: Fast Current Loop innovation helps motors work smarter, not harder

For high-volume manufacturing and industrial robots, microseconds matter.Intelligent machines shape the world around us.

At the heart of powerful automated motion technology are countless electric motors and motor drives, sometimes referred to as industrial servo drives. And now – thanks to new software and other innovations from our company – system designers are able to make those drives smarter, smaller and faster.

“When today's industrial automation innovators set out to build better motor drives, they aren't just trying to deliver more raw power so they can move heavier car parts or build bigger products,” said Marketing Manager Brian Fortman. “They're trying to design motor drives that turn motors into smart motion actuators and make the industrial machines more productive and efficient.”

Today’s smart motors

Today's robots can help physicians perform complex surgical procedures or manufacturers build products ranging from dollhouse furniture to massive trucks. Factory machinery picks up and places parts where they are needed at the next step on an assembly line or prepares packages for customer delivery. Automated lathes quickly mold and carve finished products from solid blocks of wood or metal, and 3-D printers build everything from toys to buildings from plastic, metal or concrete.

In the landscape of automated motors, “smarter" means being able to make more torque adjustments per second and to make those adjustments more accurately. That leads to improved manufacturing speeds, reduced waste and errors, and higher-quality outcomes.

Sophisticated industrial motors are all guided by motor drives based on an embedded computer chip called a microcontroller (MCU) or microprocessor (MPU). Our DesignDRIVE engineering team has enhanced the C2000™ MCU line with its new Fast Current Loop (FCL) software solution, which makes it easier for motor-drive designers to deliver smarter products to their industrial customers. And, in turn, those customers can build more advanced robots, manufacture better products, and innovate more than ever. (Learn more by downloading our white paper.)

Fast Current Loop: When microseconds matter

The MCU ensures that the motor moves where it is needed at every moment, while also tracking currents, position and operating conditions. It takes a great deal of precisely timed high-speed mathematics and synchronized measurements to design a great motor drive.

For high-volume manufacturing and industrial robots, microseconds matter. The faster a motor can be controlled to respond and move, the more accurate the resulting motions will be. Saving millionths of a second by having motors respond more quickly can also increase manufacturing output, making factories more efficient and cost-effective.

But until recently, servo-drive designers who wanted to be able to make their motors respond in less than one microsecond had limited choices. One common solution was to add specialized chips to the motor's controller board to handle some of the tasks an ordinary, general purpose MCU couldn't do within the microsecond window. Instead of being commercial, off-the-shelf components, these chips typically are specially designed for each new motor.

But adding more chips makes motor drives more expensive, more power-consuming and more complex to design. These chips take up additional space on the controller board, making the overall motor drive larger, more costly and more power-hungry.

Our C2000 MCU engineers have developed a new solution to this problem: Fast Current Loop (FCL). FCL, an innovative software available for the latest C2000 MCUs, makes it possible to update the actuation of the motor within one microsecond from sampling the current, using the existing resources used in leading servo motor drive designs.

And FCL isn't the only innovation in C2000 MCUs. Combined with C28 platform innovations such as dedicated trigonometric instructions useful for motor positioning, FCL is changing the way designers think about the next generation of motor drives – and that's good news for the industrial future.

"FCL technology quite simply breaks many long-held assumptions," Brian said. "FCL avoids the trade-offs of adding hardware for additional current loop performance or increasing inverter frequency for improving control bandwidth."

Rise of the machines

Because of the C2000 commitment to the industrial market, the commercial, off-the-shelf C2000 MCUs offer predictable long-term availability over many custom chips. Since some servos can operate in factory settings for 20 years or more, supply longevity matters.

Single-chip solutions also help motor drive designers miniaturize – to create new products using fewer chips and with smaller housings. Multi-chip control solutions, even when based on custom chips, might need a drive board thousands of square millimeters in size. A drive control system-on-chip, like a C2000 MCU, can cut that down to just a few hundred square millimeters.

That's important, because a single drive and motor is sometimes just one component in a much larger machine. Robotic arms are typically made up of several motors, each creating one axis of movement. Motor-drive combinations that can do the same amount of work with less space and less weight allow more flexible designs, and can spur more innovation from industrial machine designers.

"In some cases, electronic hardware miniaturization means designers can start to think about more economical or higher performance architectures,” Brian said. “Placing more control directly at each motorized axis on a robot, for example, can mean a significant reduction in cabling and installation costs on the machine."

For more than 20 years, our engineers have been designing MCUs to meet the specific needs of industrial automation and motion control customers. FCL, and other enhancements created by the C2000 MCU DesignDRIVE team, are helping designers create machines that can do more work with less waste, more precision, lower power consumption and in smaller spaces.

"We're designing these innovations for C2000 MCUs," Brian said, "because that’s what our customers are demanding."