Rotation angle detector

A steering system, comprising:

• a rotation angle detector, the rotation angle detector having:
• a rotation sensor configured to detect (i) a rotation angle of the motor and (ii) a number of rotations of the motor, the rotation sensor configured to receive a supply of voltage from a first chargeable power source;
• a second chargeable power source disposed separately from the first chargeable power source and configured to supply voltage to the rotation sensor;
• and a charger configured (i) to supply an electric power from the first chargeable power source to the second chargeable power source to charge the second chargeable power source, and (ii) to control whether to charge the second chargeable power source, wherein the second chargeable power source supplies voltage to the rotation sensor, regardless of whether the first chargeable power source is supplying voltage to the rotation sensor, and the charger is further configured to charge the second chargeable power source in response to an alternator charging the first chargeable power source.

An apparatus for detecting rotation angle of an electric power steering motor of a vehicle, comprising:

• a rotation sensor configured to detect rotation of the motor and to receive a supply of voltage from a first chargeable power source, the rotation sensor including:
• a rotation angle sensor configured (i) to receive a supply of voltage from the first chargeable power source when a power switch is turned ON, and (ii) to detect (a) therotation angle of the motor or (b) information corresponding to the rotation angle of the motor;
• and a rotation number sensor configured (i) to receive a supply of voltage from the first chargeable power source regardless of an ON position or an OFF position of the power switch, and (ii) to detect the number of rotations of the motor;
• a second chargeable power source disposed separately from the first chargeable power source and configured to supply voltage to the rotation sensor;
• and
• a charger configured (i) to supply an electric power from the first chargeable power source to the second chargeable power source to charge the second chargeable power source, and (ii) to control whether to charge the second chargeable power source, the charger further configured to charge the second chargeable power source in response to an alternator charging the first chargeable power source, wherein the second chargeable power source supplies voltage to the rotation sensor, regardless of whether the first chargeable power source is supplying voltage to the rotation sensor, the second chargeable power source is further configured to supply voltage to the rotation number sensor, the second chargeable power source has an electric power storage capacity configured to supply the continuous voltage to the rotation sensor for a preset time period, when the voltage of the first chargeable power source lowers, or the voltage supply from the first chargeable power source is interrupted, the electric power storage capacity of the second chargeable power source is configured to enable a continuous voltage supply to the rotation sensor for a required time period that is required for a replacement of the first chargeable power source, the second chargeable power source includes a plurality of power sources, each of the plurality of power sources configured to supply the rotation sensor with voltage, and the second chargeable power source includes a battery or a capacitor.