3-Phase Alternator Voltage Regulator
Created: Aug 10, 2015
No description available.
This reference design features a voltage regulator circuit for 3-phase alternators. Alternators are electrical generator that convert mechanical energy into electrical energy. Before, vehicles used DC dynamo generators with commutators to charge their battery. When the silicon diode rectifier was invented, vehicles now use alternator to charge the battery and power up the electrical system because it is much lighter, cheaper and more rugged. Alternator uses slip rings which extends brush life over a commutator. Both DC dynamo generator and alternator initially produces alternating current. In DC dynamo generator, AC current is generated in the rotating armature and then converted to DC by the commutator and brushes while in alternator, the AC current is generated in the stationary stator and rectified by diode rectifiers.
In this circuit, the IC CS3361 is used to control the amount of the alternator field current. The magnetic field of the alternator rotor is produced when a current is injected into the field or the rotor winding of the alternator. The output voltage of the alternator is dependent to the magnetic field strength, therefore by controlling the amount of field current the output voltage of the alternator can be controlled also. The field current is dependent on the duty cycle set by the IC regulator. The voltage at the Sense pin of the regulator determines the duty cycle. A low voltage on the sense pin produces long duty cycle while a high voltage means short duty cycle. The purpose of the Stator pin is to monitor the voltage from the stator to check if the engine stopped. The Lamp pin will turn high if the stator timeout expires. Also, the Lamp pin will turn high if there is an overvoltage condition detected at the Sense pin. If the voltage continues to increase, the field and lamp output will turn off. The SC pin monitors the field voltage so that if the drive output and the SC voltage are both high for a long period the output will be disabled.
The whole system is composed of a regulator, alternator, rectifier, indicator and a battery. These components must be placed properly in an area that fits their operating temperature range condition. To connect these components, an automotive wire with the right current rating must be used and attach these components according to their connection shown in the circuit. The TE Connectivity 1986713 terminal block connectors allow all of these components to be connected. These terminal blocks can withstand voltage up to 600V and current up to 130A.