Voltage Rectification

Voltage Rectification












The battery and the electrical system cannot store or use the 3-phase AC voltage produced by a generator, it must be rectified or converted to DC voltage.

A diode rectifier bridge is used to make the conversion.

The diode is similar to a non-return or one way valve which permits the passage of a fluid or gas in only one direction.

In a simple conversion the rectifier diode suppresses the negative halt waves and allows only positive half waves to pass.

To make use of the negative value half waves full rectification is applied.

Full rectification of the negative half waves invert them into positive half waves.

The result is a rectified pulsating direct current.

Three-Phase Voltage Rectification

Six diodes are used to achieve three-phase AC voltage rectification. Three diodes are positive biased and three are negative biased.

The positive half-waves pass through the positive biased diodes and the negative halfwaves through the negative biased diodes.

Diode rectification of the negative half-waves invert them into positive half-waves.

With full rectification DC voltage supplied to vehicle by generator is not ideally smooth, but exhibits a slight ripple. This ripple is further smoothed by the battery which is connected in parallel with the generator.

The rectifier diodes in the generator not only convert the current but also prevent battery discharging through the 3 phase windings of the stator. Current flow can only take place from the generator to the battery.