When a vehicle is running, the alternator produces electric power for the electric devices. The alternator also charges the battery that powers those devices when the engine is stopped.

In recent years, vehicle power consumption has increased with the emergence of information and communication products such as navigation systems, and electronic control products to improve comfort and safety and make vehicles environmentally friendly. To meet the demand for additional power, alternators must produce electric power more efficiently with smaller size and lighter weight. DENSO has been developing a variety of alternators that meet those requirements for a variety of vehicles including passenger cars, motorcycles, and large trucks.

DENSO Technology – Leading the World
In 2000, DENSO introduced the world’s first SC (Segment Conductor) alternator using a rectangular conductor for its stator coil. By raising the winding density (space factor) from 45 percent to 70 percent, DENSO made the SC alternator 20 percent lighter and increased the output 50 percent higher than a conventional type.

The alternator generates alternating current at the stator coil when the rotor (rotor coil) is rotated by the engine torque through a belt. The diode then rectifies the alternating current into direct current. Because the voltage generated by the alternator varies depending on the engine speed, the alternator has a regulator that controls the voltage to be constant.

Technology Evolution

Alternator with Separate Regulator

  • First alternator using a silicon rectifier.
  • Separate contact regulator.

Alternator with Integrated IC Regulator

  • Produced higher output using a cold forged rotor core to improve magnetic circuit.
  • Reduced size and weight by using internal regulator IC.

Alternator with Small Internal Fan

  • Increased output by optimizing stator and rotor sizes to improve the magnetic circuit and decreasing the pulley diameter for a faster rotor.
  • Fan having two fan blades, integrated with the rotor, reduces fan noise, size and weight.

SC Alternator

  • Using the world’s first rectangular conductor in the stator coil increases winding density, reduces weight and increases output.
  • One chip IC regulator