Nidec's Technical Capabilities

Brushless Motors

Brushless DC motors exhibit reduced energy use, long life, low noise, compact size and light weight characteristics.
Nidec is the world leader in the development and production of these high-performance motors.

Brush DC motors have various advantages such as high efficiency, potential to downsize, ability to run on electric power, and low manufacturing costs. However, these motors have a number of disadvantages such as noise due to brush friction, generation of sparks and electrical noise, and limited life due to brush wear. Development of the brushless DC motor has solved all these problems.

In the brushless DC motor, the rotor, made of a permanent magnet, is driven by the magnetic force of the stator's winding circuit. While the brush DC motor uses a brush and commutator for current switching, the brushless DC motor uses a sensor and an electronic circuit for current switching. Development of this motor has been made possible due to the evolution of the semiconductor and peripheral device technologies. This motor has advantageous characteristics of DC motors (current and voltage are respectively proportional to torque and rotating speed) and AC motors (brushless structure). Features of the brushless DC motor include compact size, high output, long life, and no generation of sparks and noise, and it is used in a wide range of applications from PCs to home appliances.

Characteristics and Classification of Brushless DC Motors

The brushless DC motor "rotates its magnet".

The rotor, made of a magnet, is rotated by magnetic fields that are generated by the current flowing through the stator windings. The current is switched by the sensor and electronic circuit.

Outer rotor type (the rotor is outside the stator)

Outer rotor type
  • Easy to obtain large torque.
  • Speed is stable during constant rotation.
  • The rotor is large (the motion is slow).
  • The outside rotor requires appropriate safety measures.

Inner rotor type (the rotor is inside the stator)

Inner rotor type
  • The rotor is small and can respond quickly.
  • The coil is located on the outside and the level of heat dissipation is high.
  • Difficult to obtain large torque.
  • Magnets can be damaged by centrifugal force.

Motor Type Comparison Table

Brushless DC motors have many advantages (in particular in the area of efficiency).

When compared to other types of motor, the brushless DC motor has many advantages such as compact size, high output, low vibration, low noise, and long life.

Item/Motor AC motor Universal motor Brush DC motors Brushless DC motor Stepping motor Servo motor
Single-phase Three-phase
AC servo DC servo
Power type AC AC/DC DC DC (including driver)/Driver Drivers Drivers Drivers
Efficiency 40-60% 60-70% 70-80% 50-60% 60-80% 80%- 60-70% 50-80% 60-80%
Size (same output) Large Intermediate or large Large Small Small Intermediate Small or intermediate Small
Noise Small Large Large Small Intermediate Small Large
Speed range Narrow Wide Intermediate Wide Wide Wide Intermediate Narrow
Response Slow Slow Intermediate Intermediate Intermediate Fast
Service life Long Short Short Long Long Short
Price Low Intermediate Low Low Intermediate or high Intermediate High
Applications Washing machines
Air blowers
Vacuum cleaners
Air conditioners
Industrial machinery
Washing machines
Vacuum cleaners
Electric tools
Electric toys
Electric tools
Automobile electric components
Small home appliances
Air conditioners
Washing machines
Small home appliances
Small home appliances
Air-conditioning equipment
Machine tools
Working machines
Judgment Cost focused Versatility focused Cost focused Cost focused Efficiency focused
Versatility focused
Versatility focused Performance focused

Nidec has a significant amount of experience in the fields of small brushless DC motors. The company has an 80% share of the global market for HDD spindle motors, a 60% share of the global market for DVD and other ODD motors, and a 40% share of the global market for fan motors. Nidec operates in the field of small precision motors that has experienced the most rapid shift to brushless motors. We succeeded in mass production of brushless DC motors earlier than our competitors and achieved a leading position in the market. In addition, we have held on to the world's No. 1 position by constantly introducing new technologies, such as the industry first employment of FDBs (Fluid Dynamic Bearings) that meet the needs of increasingly precise HDDs, as well as our in-house creation of design and simulation tools.

The market that is becoming the most fertile as an application field of brushless DC motors is the in-vehicle motor market. As evidenced by the power steering system whose level of fuel consumption can be improved by 3 to 5% if the hydraulic system is replaced by an electric system, the energy saving effect is very high due to the use of electric power systems. In various locations, more and more hydraulic systems are being replaced with motors. In particular, the brushless DC motor plays a leading role in function replacement where controllability is required and locations where parts are frequently used and thus long-life parts are required. The main area of application after power steering systems is compressor motors of air conditioners. Also, traction motors for electric vehicles (EVs) are a promising area for brushless DC motors. Because the system is operated on limited battery power, the motor must be highly efficient and compact so that it can be mounted in small spaces. With the experience we have accumulated so far in small precision motors, we are aiming to become the world's No. 1 company operating in the field of in-vehicle motors.

The in-vehicle component market is expanding significantly as an application field for brushless DC motors.