Vehicle power supply device

• US 7,847,429 B2
• Filed: 03/11/2009
• Issued: 12/07/2010
• Est. Priority Date: 03/12/2008
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Yasuoka, Kentaro, Miyama, Syuji
• Primary Examiner(s): Fureman; Jared J
• Assistant Examiner(s): Amrany; Adi
• Application Number:
  US12/401,880
• Publication Number:
  US 20090230766A1
• Time in Patent Office: 636 Days
• Field of Search: 307/9.1
• US Class Current: 307/9.1
• CPC Class Codes: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

The present invention provides a vehicle power supply device that is capable of suppressing deterioration of a capacitor, shortening a precharging time, and suppressing power loss. An ECU estimates a polarization condition of a battery after a key has been switched OFF (IG SW_OFF), and opens a main relay after determining that the polarization condition of the battery has been eliminated. Thus, a voltage difference between a battery voltage and a capacitor voltage when the main relay is subsequently reconnected can be reduced. Hence, even when the capacity of the capacitor is increased, the time required for precharging can be shortened, and energy regeneration and so on can be realized efficiently within a short time period after switching the key ON. In this case, a situation in which the post-release capacitor voltage is maintained at an unnecessarily high level can be prevented even when charging polarization occurs in the battery, and as a result, deterioration of the capacitor can be suppressed.

Claims

1. A vehicle power supply device, comprising a secondary battery, a capacitor connected parallel to said secondary battery, a relay interposed between said secondary battery and said capacitor, and relay control means for open-controlling said relay after a key is switched OFF,

the vehicle power supply device further comprising polarization estimating means for estimating a polarization condition of said secondary battery after said key has been switched OFF,

wherein said relay control means opens said relay when polarization in said secondary battery is estimated to have been eliminated by said polarization estimating means.

2. The vehicle power supply device according to claim 1, wherein said polarization estimating means estimates that said polarization in said secondary battery has been eliminated when an elapsed time after said key is switched OFF reaches or exceeds a set time.

3. The vehicle power supply device according to claim 2, wherein said set time is set variably on the basis of a temperature of said secondary battery.

4. The vehicle power supply device according to claim 2, wherein said set time is set variably on the basis of a parameter that is calculated on the basis of an SOC and an actual voltage of said secondary battery.

5. The vehicle power supply device according to claim 1, wherein said polarization estimating means calculates an open circuit voltage on the basis of at least an SOC of said secondary battery, and estimates that said polarization in said secondary battery has been eliminated when an actual voltage of said secondary battery falls below said open circuit voltage.

6. The vehicle power supply device according to claim 1, wherein said polarization estimating means estimates that said polarization in said secondary battery has been eliminated when a variation in a voltage of said secondary battery falls below a set variation.