Controlling inductive power transfer systems
First Claim
1. A portable device separable from a primary unit, the portable device comprising:
- a secondary adapted to couple with a field generated by a primary unit such that power is received inductively from the primary unit without direct electrical conductive contacts, said secondary adapted to impose a load associated with the portable device on the primary unit;
a load control unit operably coupled to said secondary, said load control unit capable of selectively changing said load imposed by the portable device on the primary unit;
wherein said load control unit is configured to affect said load to impose a first load on the primary unit during a first measurement period conducted by the primary unit to determine friendly parasitic information about the portable device;
wherein said load control unit is configured to affect said load to impose a second load on the primary unit during a second measurement period conducted by the primary unit to determine friendly parasitic information about the portable device, wherein said second load is different from said first load; and
wherein at least one of the first and second loads is based at least in part on a friendly parasitic load of the portable device.
1 Assignment
0 Petitions
Accused Products
Abstract
An inductive power transfer system comprises a primary unit, having a primary coil and an electrical drive unit which applies electrical drive signals to the primary coil so as to generate an electromagnetic field. The system also comprises at least one secondary device, separable from the primary unit and having a secondary coil which couples with the field when the secondary device is in proximity to the primary unit. A control unit causes a circuit including said primary coil to operate, during a measurement period, in an undriven resonating condition. In this condition the application of the drive signals to the primary coil by the electrical drive unit is suspended so that energy stored in the circuit decays over the course of the period. A decay measurement unit takes one or more measures of such energy decay during the measurement period. In dependence upon said one or more energy decay measures, the control unit controls the electrical drive unit so as to restrict or stop inductive power transfer from the primary unit.
-
Citations
23 Claims
-
1. A portable device separable from a primary unit, the portable device comprising:
-
a secondary adapted to couple with a field generated by a primary unit such that power is received inductively from the primary unit without direct electrical conductive contacts, said secondary adapted to impose a load associated with the portable device on the primary unit; a load control unit operably coupled to said secondary, said load control unit capable of selectively changing said load imposed by the portable device on the primary unit; wherein said load control unit is configured to affect said load to impose a first load on the primary unit during a first measurement period conducted by the primary unit to determine friendly parasitic information about the portable device; wherein said load control unit is configured to affect said load to impose a second load on the primary unit during a second measurement period conducted by the primary unit to determine friendly parasitic information about the portable device, wherein said second load is different from said first load; and wherein at least one of the first and second loads is based at least in part on a friendly parasitic load of the portable device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method of controlling inductive power transfer in an inductive power transfer system comprising a primary unit having a primary and electrical drive circuitry connected to the primary, the system including a portable device separable from the primary unit and having a secondary adapted to couple with the primary to receive power inductively without direct electrical conductive contacts, said method comprising:
-
applying electrical drive signals to the primary so as to transfer power inductively to the portable device; imposing on the primary a first load associated with the portable device; measuring, in a first measurement period, a first quantity associated with the primary under the first load imposed on the primary; imposing on the primary a second load associated with the portable device, the second load being different from the first load; measuring, in a second measurement period, a second quantity associated with the primary unit under the second load imposed on the primary; and determining, based on the first and second quantities measured respectively under the first and second loads, presence of a parasitic load in proximity to the primary unit. - View Dependent Claims (12, 13, 14, 15, 16)
-
-
17. An inductive power transfer system including a primary unit having a primary and electrical drive circuitry connected to the primary for applying electrical drive signals thereto so as to generate an electromagnetic field, the system including a portable device separable from the primary unit and having a secondary adapted to couple with the primary to receive power inductively without direct electrical conductive contacts, the inductive power transfer system comprising:
-
a control unit operable to control the electrical drive circuitry to control application of the electrical drive signals to the primary; a measurement unit operable to take a first measurement in a first measurement period and a second measurement in a second measurement period; a load control unit configured to affect a load associated with the portable device, the load being imposed during the first measurement period and the second measurement period; wherein the load control unit is configured to affect the load to impose a) a first load on the primary unit during the first measurement period and b) a second load on the primary unit during the second measurement period, wherein the first load is different from the second load; and wherein the control unit is operable, in dependence upon the first measurement and the second measurement, to detect presence of a parasitic load in proximity to the primary. - View Dependent Claims (18, 19, 20, 21, 22, 23)
-
Specification