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What is the role of metallic copper in the motor manufacturing industry?

Date:2023-10-17   Author:XINDA MOTOR
Copper is integral to improving motor efficiency. Significant improvements in efficiency of standard induction motors require more copper in the windings, higher grade steel cores, improved bearings and insulation, and improved cooling fan designs. As the pursuit of improved motor efficiency continues, new motor technologies and designs move beyond induction motors, and copper becomes the focus of these new technologies.

permanent magnet motor

Permanent magnet synchronous motors are increasingly used in industrial motor drives. Permanent magnet motor technology replaces aluminum rods with rotor components made of rare earths with powerful permanent magnets. The permanent magnet methods are divided into surface mounting and internal mounting . The stator of a permanent magnet motor is very similar to a traditional copper-wound motor. The rotor in the motor is unique in that the permanent magnets are embedded in the rotor laminations or rod surfaces. Permanent magnet motors use less copper than similarly rated AC induction motors, however, they still rely on copper for efficiency.

In most cases, permanent magnet motors require matching variable speed drives to achieve gains, and permanent magnet motors offer up to 1.5–2% efficiency gains over good, efficient AC induction motors. Permanent magnet motors comply with the power density principle, that is to say, the size of the motor has determined the motor's horsepower, torque and efficiency. The frame structure of the motor generally compensates for changes in the length of the motor shaft.

Advantages of permanent magnet motors: excellent torque-speed curve, excellent dynamic response, high efficiency and reliability, low maintenance, longer service life, low noise, high speed capability, high torque/volume ratio or high power density. Disadvantages: High cost, variable speed drive required, sustainability of rare earth materials.
Switched reluctance motor

Switched reluctance technology has been around since the 1800s, and it was the advent of power electronics and computing power that brought this technology to the forefront of today's advanced motors. Switched reluctance motors are brushless DC motors that provide continuous torque when paired with an electronic driver. In variable speed applications, switched reluctance motors can replace and optimize induction motors. Switched reluctance motors have some distinct advantages over conventional motors in that they can operate with a phase loss or short circuit in one of the phases - a permanent magnet or induction motor system that would momentarily stop.

The amount and type of copper wire is very important in the design of a switched reluctance motor, with each turn of the coil nested together to help fill the large stator slots allowed by the switched reluctance motor design. Copper is an important component of coils, and motors are typically wound with 100% copper, which has a much lower resistance than alternative materials such as aluminum. Low winding resistance directly translates into less waste heat, thereby increasing energy efficiency and beneficially lowering the motor's operating temperature.

When necessary, switched reluctance motors use coils made of rope-like copper wire or Litz wire. The coil is made of many smaller copper wires twisted into a rope to form a rectangular shape. Using this type of wire allows the conductor to be transposed, thereby reducing the skin effect, a phenomenon that causes current to migrate to the outside of the conductor, effectively increasing the conductor's resistance.

Advantages of switched reluctance motors: high efficiency, especially in a wide load range, high torque and high speed, excellent constant power speed range function, high reliability and long life, simple and sturdy structure, high power density.

Disadvantages: ripple torque, high vibration levels, requires variable speed drive, noisy, slightly lower peak efficiency than permanent magnet motors.

Copper rotor motor

Innovation in copper rotor motor technology stems from meeting the low-voltage motor market's demand for higher energy efficiency, a demand that traditional die-cast aluminum rotor designs cannot meet. Using new copper rotor technology increases efficiency but retains the same footprint as traditional aluminum rotor designs, which is important not only for new applications, but also for retrofit applications.

In order to develop this new technology, the motor manufacturing industry redesigned the rotor, especially designing and developing complex rotor casting processes. The increased efficiency compared to conventional aluminum rotor designs justifies the substantial investment in design and development. Using die-cast aluminum technology, the die-casting of a solid copper rotor produces higher efficiency on the same size motor compared to traditional energy-saving motors.

The initial purchase price of a copper rotor motor is slightly higher than that of an aluminum rotor motor, making the payback period an important factor. The payback period is relatively short, which is generally not an issue given the 20-year design life. Copper is an amazing material that not only achieves efficiency requirements, but in many cases allows the motor to be shortened, making it more compact and achieve higher horsepower in the same footprint. Copper rotor motors are unique in that they allow us to create very efficient motors. More efficient motors run cooler and spin the rotor faster.

Advantages of copper rotor motors: high efficiency, inverter load capacity, high reliability, constant torque capability, low operating temperature, reduced maintenance costs, lower power costs, precise and better balanced rotor, lower vibration. Disadvantages: Higher initial purchase price, cast rotor, limited supply of casting machinery, higher cost of copper than other materials, more complex manufacturing process.

in conclusion

Each of these motor technologies, permanent magnet, switched reluctance and copper rotor induction motors, relies on copper design in its own unique way to produce more efficient and reliable motors. Permanent magnet motors with powerful permanent magnets in the rotor, switched reluctance motors with power electronic switches and their dense copper stator and rotor, and copper rotor motors with cold-running rotors that reduce current resistance all offer opportunities to achieve energy savings Targets and performance-enhancing options. Through innovative uses of copper, switching technology and permanent magnets, today's motor designs have more options to choose from to meet their efficiency and specific application requirements.