The present invention relates to a power steering apparatus which depends on DC power as an energy source for generating an auxiliary steering force; and more specifically, the present invention relates to a motor-driven power steering apparatus which is profitable for a passenger car using a DC motor as an actuator for generating a auxiliary steering force. 
A conventional power steering apparatus comprises a motor for generating an auxiliary steering force, a control apparatus for regulating current of the motor corresponding to the steering force, and a battery as a current source, for instance, as disclosed on FIG.  1 of Japanese Patent Laid-Open No.  59-156863 (1984), published on Sept. 6, 1984, and entitled "Power Steering Apparatus of Automobile". 
The apparatus of the prior art uses a standard battery which is used in the automobile as a current power source for all electric devices thereof.  However, the standard battery does not have the function of providing an output corresponding to the current value of the load of the automobile. 
On the other hand, a generator for charging batteries which has two armature windings connected in star connection, respectively, for generating two similar voltages is disclosed in FIG.  3 of the U.S. Pat.  No.  4,045,718, entitled "Multiple Winding Multiple Voltage Alternator Electrical Supply System". 
In the conventional power steering apparatus sufficient consideration is not given to the large current consumption of the motor for generating an auxiliary steering force and the affect thereof an other electrical systems in the vehicle.  Especially, the conventional power steering apparatus has a drawback in that the illumination provided by the headlights of the automobile is reduced and the electrical devices mounted on the vehicle, such as lights, wiper, and air-conditioner, etc.  are undesirably influenced by the steering of the wheel at night when the automobile stops or while the engine is idling.