Permanent Magnet Synchronous Fan Motors SFP

The motor technology examined in this study is an evaporator fan that uses a permanent magnet, synchronous AC motor (PMSM) with a new control design. These motors are inherently more energy efficient than all of the previously discussed motor technologies due to a number of design improvements. First, energy savings are realized through the use of permanent magnets which reduce the power necessary to operate the motor. Similar to ECMs, the use of permanent magnets eliminates the need for magnetizing current and shaft brush. However, unlike an ECM this new synchronous motor runs off existing AC current without the need to rectify the current to DC. The elimination of the rectifying electronics realizes further energy efficiency improvement. The elimination of the electronics also decreases the motor complexity while increasing the reliability and service life of the motor. Implementation of these PMSM fans has been shown to increase fan efficiency to 73%, thereby reducing both the direct energy use of the fans and the thermal load on the refrigeration system.

In support of California’s strategic goals to accelerate the penetration of Energy Efficiency (EE) technologies, SCE’s EP group, together with AESC, performed an assessment study of a new display case evaporator fan product. The primary goals were to characterize the refrigerated display case fan market and to quantify the energy savings and demand reduction of a high-efficiency fan with Permanent Magnet Synchronous Motors (PMSM). A scaled field placement of 208 fan retrofits was performed at four grocery stores in SCE territory, each in a different Climate Zone (CZ). Fan power, refrigeration system power and temperatures, weather, and case air were monitored for several months of baseline and postretrofit conditions. In addition to data logging, spot measurements of each fan were taken during the retrofits. To complement the field data, refrigeration system modeling was used to study the Interactive Effect (IE) on the compressors. Finally, a market survey of refrigeration professionals and energy managers characterized the market and baseline conditions. The 208 fan retrofits showed clear and consistent improvements in electrical demand, energy usage, and Power Factor (PF), without negatively impacting case operation or compressor power or compression ratios. As seen in the following table, savings were calculated for different baseline conditions: Low-Temperature (LT) versus Medium-Temperature (MT) cases, and Shaded Pole (SP) versus Electrically Commutated Motors (ECM). In addition to fan power savings, the reduced case heat load will result in compressor savings. Refrigeration modeling of the measure was used to determine the IE and total per-fan system savings shown in the following table. Estimated simple payback for the full measure cost was between 1.6 and 9.5 years, depending on the case and baseline motor type (at an assumed blended rate of $0.15/kWh). Incremental cost payback is much quicker, and the net present value for a total supermarket retrofit is likely tens of thousands of dollars. The market survey suggested an average baseline blend of 60% ECM and 40% SP, while the field sites had a blend of 85% ECM and 15% SP. Using these estimated existing conditions and the calculated savings, the California market potential is estimated to be 252-411 Gigawatt-hours per year (GWh/yr), which equals 60,500-98,500 metric tons of reduced CO2e emissions per year. Based on the savings results, market potential, and simple implementation, the product appears well-positioned to gain market traction. Targeted utility program support would help hasten and ensure this market adoption by mitigating market barriers such as low product awareness, low customer priority, long baseline Effective Useful Life (EUL), and case repair habits.