Voltage control unit for vehicular AC generator

• US 6,433,519 B2
• Filed: 07/06/2001
• Issued: 08/13/2002
• Est. Priority Date: 07/06/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Takahashi, Keiji, Taniguchi, Makoto, Maruyama, Toshinori
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/899,054
• Publication Number:
  US 20020003418A1
• Time in Patent Office: 403 Days
• Field of Search: 322/25, 322/27, 322/28, 322/36, 322/37, 322/18
• US Class Current: 322/28
• CPC Class Codes: H02J 2207/10 Control circuit supply, e.g. means for supplying power to the control circuit
• CPC Class Codes: H02J 7/243 with on/off action
• CPC Class Codes: H02P 9/08 Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation
• CPC Class Codes: H02P 9/305 controlling voltage H02P9/302 takes precedence

Abstract

In an apparatus for detecting a rotation by utilizing a residual magnetism remaining in a core, when a field current attenuates gradually through a current return diode during a deceleration period for the stop of rotation, there occurs an AC demagnetizing action which causes the field current to attenuate, so that also during the deceleration period, the supply of electric power to a control circuit and field current to a field coil are continued.

Claims

1. A voltage control unit for a vehicular AC generator, comprising:

a rotor having a field core including a plurality of field poles formed thereon;

a field coil to which a field current for magnetizing said field poles is supplied;

a diode for current return connected in parallel with said field coil;

an armature having an armature core including a polyphase coil applied thereon;

a rectifier circuit for rectifying a voltage generated from said polyphase coil and outputting the voltage as a DC output voltage, the DC output voltage being controlled by adjusting the field current;

switch means for switching between ON and OFF of the field current;

a control circuit for controlling said switch means in accordance with a signal associated with the DC output voltage;

a power supply circuit for supplying electric power to said control circuit; and

power supply hold means for holding the supply of electric power to said control circuit by said power supply circuit for a period from just before stop of rotation of said rotor until lapse of a predetermined time after the stop of rotation of said rotor.

2. A voltage control unit according to claim 1, wherein

based on a rotation-induced electric signal associated with the rotation of said rotor or the signal associated with the DC output voltage, said power supply hold means holds said power supply circuit in an active state during a predetermined period from a time when a number of rotation of said rotor has decreased smaller than a predetermined number until exceeding a predicted time-point of normally rotation stop of said rotor.

3. A voltage control unit according to claim 1, wherein said switch means is not turned OFF for a predetermined time or more at least during a period from just before the stop of rotation of said rotor until after a completion of the rotation stop.

4. A voltage control unit according to claim 3, wherein the switch means is turned ON continuously during the period.

5. A voltage control unit according to claim 1, wherein said power supply hold means causes the supply of electric power to said control circuit by said power supply circuit to start when a number of rotation of said rotor is more than a predetermined number, based on a rotation-induced electric signal associated with the rotation of said rotor.

6. A voltage control unit according to claim 5, wherein the rotation induced electric signal is formed by a field coil induced voltage with residual magnetism induced in said field coil by interlinkage of a residual magnetic flux in said armature core with said field core during rotation of the rotor or by an armature coil induced voltage with residual magnetism induced in said polyphase coil by interlinkage of a residual magnetic flux in said field core with said polyphase coil.

7. A voltage control unit according to claim 6, wherein said power supply hold means includes:

timer means which operates when the number of rotation has reached a predetermined value by the field coil or armature coil induced voltage with residual magnetism as the rotation induced electric signal; and

comparator means for determining whether the DC output voltage has exceeded a predetermined voltage or not, wherein

said power supply hold means causes the supply of electric power to said control circuit by said power supply circuit to start in accordance with an OR output of both output of said timer means and output of said comparator means.