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Startup eyes better motor control for the IoT

March 19, 2018

rick.merritt-March 19, 2018

SAN JOSE, Calif. — A startup designing a new kind of smart, networked motor provides a view into the state of the Internet of Things. So far, Software Motor Company (SMC) has found that lowering costs through integrated designs may be one key to success in an IoT market that has not yet lived up to its hype.

SMC makes switch magnetic reluctance motors that it claims are more efficient and reliable than traditional inductance motors. It currently sells a 5-horsepower motor for five- to 15-ton HVAC systems that draw nearly half a building’s energy use. Test customers include national retail grocery and restaurant chains and biomedical and professional offices.

“We have seen energy reductions of 50% and more in HVAC systems with our motors … we also are working with a number of OEMs to eliminate gearboxes and replace mechanical complexity with our advanced software-controlled motors,” said Ryan Morris, SMC’s executive chairman.

The key to the new motor is a custom inverter. It adjusts current about 20,000 times per second to generate the three-phase magnetic field that drives the motor.

“What’s really tricky is determining the position of the rotors in flight relative to the coils … You need to know where the rotor is to within half a mechanical degree of rotation,” said Trevor Creary, SMC’s chief technologist and a veteran designer of computer chips for Broadcom and the former Sun Microsystems.

A 200-MHz TI Delfino C2000 DSP does the heavy lifting, running algorithms and firmware that SMC’s engineers spent 18 months developing. The work required collaboration from specialists in motor control, magnetics, finite-element analysis, and power electronics. The design also uses a custom power module from Semikron.

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A C2000 DSP and custom power module are at the heart of a custom inverter. Click to enlarge. Images: SMC.

One of the DSP’s two cores handles external communications over Modbus or other protocols to a separate SMC industrial controller. The controller uses an embedded TI ARM Cortex-A8 processor to track sensor data from the motor and the HVAC system.

SMC struck a deal with Tridium to embed its Niagara management software in the controller to monitor and control the motor and HVAC. “You shouldn’t have to be a firmware programmer to write flow-control programs,” said Creary.

Customers like the dashboard that the controller provides, but they chafe at the costs of a separate industrial controller. In addition, the controller talks over wired or Wi-Fi links to a third-party LTE gateway, typically sourced from carriers, that comes with a data plan.

 

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The magnetic reluctance motor uses six coil windings to define its three phases. Click to enlarge.

Continue reading page two on Embedded's sister site, EE Times: "Motor maker revs up for IoT."

 

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