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Several
design elements were responsible for the increased energy
efficiency of EPC's new evaporator motor, according to Darrell
Schuh, A.O.
Smith Electrical Products Company (EPC engineer.
"The rotor was designed with magnetic
ferrite materials, while using standard commercial grade
steel laminations for the stator and an electronic control
board for current control," he explains. |
The new designs are intended to replace current
C-frame models of evaporator motors and condenser motors in frost-free
refrigerators.
Instead of relying on standard brushless d.c. technology
to achieve the efficiency gains, EPC decided to transform its standard
C-frame motors
into brushless d.c. models. According to Darrell Schuh, engineering manager
for Subfractional Motors, EPC chose this approach to provide users with
a motor that would require no mechanical changes in the end unit, but
would still give a substantial energy-efficiency improvement. This, he
says, was not only in response to customer requests for "drop-in" replacement
products, but was also part of EPC's proactive goal to develop a system
that is much more efficient than other products currently on the market.
The
company also wanted the new designs to help appliance producers reach
the energy efficiency standard recently established by the U. S. government,
and to make it easier for manufacturers to achieve and display the
Energy Star(R) rating for high efficiency.
Because EPC already supplies evaporator
products to its appliance customers, it elected to pursue the redesign
of the evaporator motors before developing
the new condenser motors. A design team made up of Corporate Technology,
Electrical Products' Electronics Group, and its Ventilation and Refrigeration
(V & R) Design Group worked together to develop the evaporator motors
and to overcome several design challenges such as space and mounting
constraints.
Corporate Technology came up with the concept of a permanent-magnet
motor, using ceramic ferrite magnets, with the drive electronics mounted
on
the motor. The EPC Electronics Group and V & R Design Group then
took those initial concepts and refined the design of the evaporator
motor using new 3D CAD software.
The goal was to maintain the basic width
of the motor so it could continue to use the same mounting bracket.
To achieve that, A.O. Smith designers took the
basic motor design, customer-supplied proofs, and 3D parts and designed a 3D
motor that fit the space, while, at the same time, blocking out an area for
mounting the electronics to the motor.
Pre-production prototypes of the evaporator motors
have been shipped to customers, and mass production will begin toward the end
of the third quarter, says Mr.
Schuh.
The next phase of the redesign project is to replace the unit-bearing
condenser motor with a brushless d.c. design. According to EPC,
this would represent a
significant improvement for customers since traditional, unit-bearing, shaded-pole
motors are typically inefficient. Design plans include applying electronics
to make the motors more efficient. |
