Inductive battery recharging system with peak voltage detection

• US 7,208,912 B2
• Filed: 09/24/2004
• Issued: 04/24/2007
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Ghabra, Riad, Tang, Qingfeng
• Primary Examiner(s): Tso; Edward H.
• Application Number:
  US10/949,498
• Publication Number:
  US 20060071632A1
• Time in Patent Office: 942 Days
• Field of Search: 320/108, 320/109
• US Class Current: 320/108
• CPC Class Codes: G01V 3/101 by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence

Abstract

A method is provided for inductively charging a rechargeable battery of a portable device in a vehicle via a primary circuit that includes a primary inductive coil, a secondary circuit that includes a secondary inductive coil, and a rectifying circuit electrically coupled to the rechargeable battery. A primary coil is energized with a supply voltage. A frequency of the supply voltage is varied. A peak voltage of the primary circuit is detected. The frequency of the supply voltage is adjusted to a respective frequency associated with the peak voltage.

Claims

1. A method of inductively charging a rechargeable battery of a portable device in a vehicle via a primary circuit that includes a primary inductive coil, a secondary circuit that includes a secondary inductive coil, and a rectifying circuit electrically coupled to said rechargeable battery, said method comprising the steps of:

energizing said primary inductive coil with a supply voltage;

varying a frequency of said supply voltage;

detecting a peak voltage of said primary inductive coil; and

adjusting said frequency of said supply voltage to a respective frequency associated with said peak voltage.

2. The method of claim 1 wherein said step of varying said frequency of said supply voltage includes sweeping said frequency within a predetermined bandwidth.

3. The method of claim 1 wherein a controller determines said frequency adjustment and automatically adjusts said frequency of said supply voltage.

4. The method of claim 1 wherein a phase locked loop determines said frequency adjustment and automatically adjusts said frequency of said supply voltage.

5. A method of inductively charging a cellular telephone rechargeable battery in a vehicle via a primary circuit that includes a primary inductive coil, a secondary circuit that includes a secondary inductive coil, and a rectifying circuit electrically coupled to said rechargeable battery, said method comprising the steps of:

energizing said primary inductive coil with a supply voltage;

varying a frequency of said supply voltage;

monitoring a voltage across said primary inductive coil;

determining a peak voltage as said frequency of said supply voltage is varied across said primary inductive coil; and

adjusting said frequency of said supply voltage to a respective frequency associated with said peak voltage.

6. The method of claim 5 wherein a controller determines said peak voltage and automatically adjusts said frequency of said supply voltage for maximizing said voltage across said primary inductive coil.

7. The method of claim 5 wherein a phase locked loop provides said peak voltage by locking on to a resonance formed by said primary inductive coil.

8. A charging system for inductively charging a rechargeable battery of a portable device in a vehicle, said charging system including a vehicle-based recharging unit that maximizes a supply voltage inductively supplied to said rechargeable battery, the system comprising:

a primary circuit including a control device and a primary inductive coil, said control device varying a frequency of said supply voltage to said primary inductive coil, said control device detecting a peak voltage of said primary inductive coil; and

a secondary circuit including a secondary inductive coil, said primary inductive coil inducing a voltage in said secondary inductive coil;

wherein said control device adjusts said frequency of said supply voltage to a respective frequency associated with said peak voltage for maximizing said supply voltage inductively to said rechareable battery.

9. The charging system of claim 8 wherein said control device includes a microprocessor.

10. The charging system of claim 9 wherein said microprocessor provides a drive signal to at least one voltage driver for varying said frequency of said supply voltage.

11. The charging system of claim 8 wherein said control device includes a phase-locked loop.

12. The charging system of claim 8 wherein said frequency is varied within a predetermined bandwidth for determining said respective frequency associated with said peak voltage.