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‘Re-invented’ fan motor cuts energy use by up to 80%

30 September, 2015

A US company claims to have developed a new class of high-efficiency motor that that can cut energy consumption by up to 80%, while improving power quality. Missouri-based QM Power says that its Q-Sync smart synchronous motor – aimed initially at refrigeration fan applications – will also improve reliability and allow energy-saving retrofits at a similar cost to conventional motors. QM is planning to expand the technology into other applications.

The company’s claims have been backed by the US Department of Energy (DOE), which has helped to fund the development and testing of the motor and has issued a report describing it as a “high-impact technology”. On the basis of one field trial, the DOE calculates that retrofitting the new motors to refrigeration and HVAC system across the US could save the nation around 300TWh a year.

“Motors can consume up to 70% of all the energy used in commercial buildings, but amazingly there has been little-to-no innovation in motor efficiency over the past half-century,” says QM Power’s co-founder, president and CEO, PJ Piper. “With Q-Sync, we’ve reinvented the fan motor to exceed modern-day energy and environmental requirements, deliver bold new energy savings opportunities and dramatically reduce grid congestion. The motor can now be the next meaningful retrofit and OEM opportunity for energy savings in commercial buildings.”

Until now, the commercial refrigeration industry has had two main choices for fan motors: induction, or shaded-pole, motors, developed in the 1880s, which account for more than 65% of all commercial refrigeration motors in the US and are only 20% efficient; and electronically-commutated motors (ECMs), developed in the 1960s, which currently have a 35% market share and are about 60% efficient.

The new Q-Sync motor has a claimed efficiency of 75% and is similar in cost to an ECM. At the heart of the patent-pending design is a simpler, smarter controller.

Conventional ECM motors require continual conversion between AC and DC power. By contrast, once the new motor reaches its operating speed, it shifts to AC power direct from the grid, eliminating the need for continuous power conversion. And its permanent magnet design eliminates the additional energy requirements and slip associated with shaded-pole motors. The result is a motor that is said to provide a reduction in energy consumption of up to 80%, both at the meter and at the grid.

The technology is based on a split-wound stator coil and a controller that uses a Hall effect sensor to detect the rotor position. At start-up, or when the sensor detects that the motor is not running at synchronous speed, the controller varies the frequency of the current delivered to the stator coil to bring the motor up to synchronous speed. When the frequency is the same as the input and the motor is running synchronously, the controller is switched off until either the motor falls out of synch, or is stopped and restarted. If the motor falls below the synchronous speed, the controller adjusts the motor timing as it does at start-up.

Previously, synchronous motors have been prohibitively expensive for commercial refrigeration evaporator fan applications because of the high cost of the electronic control circuitry needed to bring the motors up to synchronous speed. The Q-Sync’s controller is simpler and lower in cost, making the new motors a cost-effective alternative for the commercial refrigeration market.

And, because its electronic circuitry runs for a fraction of the time required for an ECM motor, the Q-Sync motor is said to be more reliable and to last longer.

As well as transforming electrical energy into mechanical energy more efficiently than an ECM, the Q-Sync motor is said to have a much higher power factor, so it accepts energy from the grid more efficiently. It also reduces stresses on the grid and can help utilities to reduce spikes in energy use and costs.

“The introduction of Q-Sync will lead to a significant reduction in energy consumption and CO₂ emissions,” predicts Dr Bryan Becker, a professor at University of Missouri–Kansas City’s School of Computing and Engineering and a former chairman of Ashrae’s Technical Committee for Refrigeration Applications for Foods and Beverages. “Using Q-Sync technology instead of state-of-the-art electronically-commutated motors would be the energy equivalent of taking one of every two motors off the grid. And, using Q-Sync technology instead of shaded-pole motors would be the equivalent of taking four of every five motors off the grid.”

QM Power says that its Q-Sync motors are the most efficient fan motors on the market

The US DOE has been working with QM Power, as well as OEMs, supermarkets, service and retrofit contractors, and utilities, to install and demonstrate more than 10,000 Q-Sync fan assemblies in more than 50 grocery stores across the US.

A new report from the DOE’s Oak Ridge National Laboratory (ORNL) documents the results from one field trial, which compared two 12W Q-Sync motors with two 12W EC motors used in a refrigerated display in a supermarket. The trial found that the power consumption of the new motor was 27.4% lower than the EC motors, and the current it drew was 53.3% lower. The efficiency of the Q-Sync motor was 73.1% compared to 53.1% for the ECM, while the Q-Sync’s power factor was 0.936 compared to 0.601 for the ECM.

Based on the trial, the ORNL report extrapolates to the installed base of 9–12W commercial refrigerator fan motors in the US and calculates that retrofitting these with the new motors would result in energy savings of 68% – equivalent to 4.9TWh per year (worth more than $500m).

The report also says that the higher power factor of the Q-Sync motors means that utilities would need to supply 80% less apparent power and 80% less current for the new motors, compared to the current baseline combination of shaded-pole and EC motors.

It goes on to look at the potential savings of applying the Q-Sync technology to other equipment, such as evaporator and condenser fans used in domestic refrigerators, and commercial and residential HVAC systems. Because there are hundreds of millions of these motors in the US, and they tend to be larger than the trial motors, they consume almost 30 times more energy. So, the potential savings of converting these motors to the new design could be around 300TWh. 

QM Power is offering a two-year warranty on its new motors and is introducing a financing scheme that will allow refrigeration users to retrofit the Q-Sync motors to their equipment at no cost, in exchange for sharing their energy savings with QM Power.

Initially, the company is offering the new motors in ratings from 9–12W for use on 95–140V supplies, but plans to expand the range to include ratings up to 50W and versions that will operate on 240V supplies. It is also working on multi-speed and variable-speed versions.

Another QM technology – called PPMT (Parallel Path Magnetic Technology) – uses innovative flux-concentration topologies to deliver high power and torque densities, and efficiencies for motors, actuators and generators. Magnets are arranged to create parallel flux paths and field coils to direct their magnetic flux. QM claims that the result is four times the force from a given electrical input using the same electromechanical components. PPMT actuators can stay in a “locked” position without needing additional electrical input.

Since it was founded nine years ago, QM Power has received more than $20m in venture funding, contracts and grants. It is subcontracting the manufacture of its motors, with some initial production being carried out in China.

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