Vehicle alternator having rectifier circuit using diode and FET

• US 6,731,081 B2
• Filed: 03/21/2002
• Issued: 05/04/2004
• Est. Priority Date: 05/01/2001
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kusase, Shin, Shiga, Tsutomu
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US10/101,733
• Publication Number:
  US 20020163260A1
• Time in Patent Office: 775 Days
• Field of Search: 318/140, 318/141, 318/147, 318/156, 318/157, 318/158, 322/28
• US Class Current: 318/140
• CPC Class Codes: H02K 1/2773 consisting of tangentially magnetized radial magnets
• CPC Class Codes: H02K 11/05 Rectifiers associated with casings, enclosures or brackets
• CPC Class Codes: H02P 9/305 controlling voltage H02P9/302 takes precedence

Abstract

A vehicle alternator includes a permanent magnet rotor, a stator having armature coils, and a rectifier circuit. In the rectifier circuit, schottky barrier diodes and FETs are connected in series so that the forward directions of the schottky barrier diodes and parasitic diodes of the MOSFETs are opposite. The schottky barrier diodes are connected between the MOSFETs and the armature coils.

Claims

1. A vehicle alternator comprising:

a rotor having permanent magnets;

a stator having armature coils for generating alternating current outputs in response to rotation of the permanent magnets of the rotor; and

a rectifier circuit for converting the alternating current outputs to a direct current output,

wherein the rectifier circuit includes series connections of a first end of a first diode with a FET having a second diode as a parasitic diode, each of the series connections being connected to each of the armature coils by a second end of the first diode, and

wherein the first diode and the second diode are arranged in each of the series connections so that forward directions of the first diode and the second diode are opposite.

2. The vehicle alternator as in claim 1, wherein the first diode is a Schottky barrier diode.

3. The vehicle alternator as in claim 1, wherein the rectifier circuit further includes a third diode connected in series to each of the series connections, so that the first diode and the third diode full-wave rectifies the alternating current output under a condition that the FET is turned on.

4. The vehicle alternator as in claim 3, wherein the first diode has a forward voltage lower than that of the third diode.

5. The vehicle alternator as in claim 1, wherein the first diode is connected between the armature coil and the FET.

6. The vehicle alternator as in claim 1, wherein the rectifier circuit includes full-wave rectifying bridges corresponding to output terminals on which the alternating current outputs appear respectively, each of the full-wave rectifying bridges includes a negative potential side and a positive potential side, and each of the full-wave rectifying bridges has the series connection of the first diode and the FET provided at the negative potential side or the positive potential side.

7. A vehicle alternator comprising:

a rotor for generating a fixed rotating magnetic field when rotated;

a stator having armature coils for generating alternating current outputs in response to the fixed rotating magnetic field; and

an electric circuit including rectifying diodes connected in a full-wave rectifier bridge configuration for converting the alternating current outputs to a direct current output,

wherein the electric circuit further includes FETs, each FET connected to corresponding plurality of rectifying diodes for controlling output power generation of the armature coils when turned off, and

wherein the FET is arranged so that parasitic diode thereof is biased in reverse to the corresponding rectifying diodes.

8. The vehicle alternator as in claim 7, wherein:

the electric circuit has series connections in correspondence to the armature coils;

each of the series connections includes series-connected first and second rectifying diodes and FET;

each of the armature coils is connected to a junction between the first and the second rectifying diodes; and

the first diode connected to the FET in one arm of the bridge configuration has a forward voltage lower than the second diode.

9. The vehicle alternator as in claim 7, wherein the rotor is a permanent magnet type, and the rectifying diodes and the FETs are connected in series, respectively.