in a double role

In start-stop systems, a suitably modified traditional starter is most often used to start the engine, but there are solutions where starting is done using a so-called reversible generator.

Such a device called StARS (Starter Alternator Reversible System) was developed by Valeo. The basis of the solution is a reversible electric machine that combines the functions of a starter and an alternator. The starter-alternator, installed instead of the classic generator, provides a quick and at the same time very smooth start-up, since there is no gearing in it. The torque generated by the reversible alternator when starting the engine is transmitted through a belt drive to the engine crankshaft.

The use of a reversible alternator in a car entails additional devices and solutions. When this machine becomes an electric motor to start the car, its rotor windings are supplied with direct current, while the stator windings must be connected to an alternating voltage system. The generation of alternating voltage from a direct current source, which is an on-board battery, requires the use of a so-called inverter. The stator windings must be powered by alternating voltage without a rectifier diode assembly and a voltage regulator. The connection of diodes and a voltage regulator to the stator winding terminals occurs as soon as the reversible generator becomes an alternator again.

Due to the placement of the rectifier diode unit, voltage regulator and inverter, the reversible generators currently produced by Valeo can be divided into two groups. In the first, the diodes, regulator and inverter are mounted on the generator, in the second, these elements form a separate unit mounted outside.