Q-factor detection method
First Claim
Patent Images
1. A wireless power transmitter, comprising:
- a transmit coil, the transmit coil configured to transmit wireless power;
a capacitor coupled in series with the transmit coil to form a resonant circuit between a first node at the transmit coil and a second node at the capacitor, the transmitter coil and the capacitor being coupled at a third node;
a bridge circuit coupled to the first node and the second node of the resonant circuit;
a charging circuit coupled to the third node and configured to charge the capacitor with a charging voltage; and
a detection circuit coupled to the third node to receive a voltage across the capacitor and provide data related to the voltage;
a control circuit coupled to the bridge circuit, the charging circuit, and the detecting circuit,wherein the control circuit controls the bridge circuit to provide current through the transmit coil to provide wireless power, and furtherwherein the control circuit determines a Q-factor by controlling the bridge circuit to ground the second node and disconnect the first node, controlling the charging circuit to charge the capacitor when the second node is grounded, when the capacitor is charged controlling the bridge circuit to further ground the first node, and receiving the data from the detecting circuit while the resonant circuit oscillates to determine the Q-factor.
2 Assignments
0 Petitions
Accused Products
Abstract
A method of measuring a Q-factor in a wireless power transmitter includes charging a capacitor in a LC tank circuit that includes a transmission coil to a voltage; starting a Q-factor determining by coupling the LC tank circuit to ground to form a free-oscillating circuit; monitoring the voltage across the capacitor as a function of time as the LC tank circuit oscillates; and determining the resonant frequency and the Q-factor from monitoring the voltage.
13 Citations
17 Claims
-
1. A wireless power transmitter, comprising:
-
a transmit coil, the transmit coil configured to transmit wireless power; a capacitor coupled in series with the transmit coil to form a resonant circuit between a first node at the transmit coil and a second node at the capacitor, the transmitter coil and the capacitor being coupled at a third node; a bridge circuit coupled to the first node and the second node of the resonant circuit; a charging circuit coupled to the third node and configured to charge the capacitor with a charging voltage; and a detection circuit coupled to the third node to receive a voltage across the capacitor and provide data related to the voltage; a control circuit coupled to the bridge circuit, the charging circuit, and the detecting circuit, wherein the control circuit controls the bridge circuit to provide current through the transmit coil to provide wireless power, and further wherein the control circuit determines a Q-factor by controlling the bridge circuit to ground the second node and disconnect the first node, controlling the charging circuit to charge the capacitor when the second node is grounded, when the capacitor is charged controlling the bridge circuit to further ground the first node, and receiving the data from the detecting circuit while the resonant circuit oscillates to determine the Q-factor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method of measuring a Q-factor in a wireless power transmitter, comprising:
-
discontinuing transmission of wireless power, the wireless power being transmitted with a transmission coil coupled in series with a capacitor between a first node and a second node and driven by a bridge circuit coupled to the first node and the second node, the transmission coil and the capacitor forming an LC tank circuit; operating the bridge circuit to ground the second node and disconnect the first node; charging the capacitor in the LC tank circuit to a charged voltage by applying a charging voltage to a third node between the transmission coil and the capacitor; when the capacitor is charged to the charged voltage, further operating the bridge circuit to ground the first node to form a free-oscillating circuit; monitoring the voltage across the capacitor as a function of time as the LC tank circuit oscillates; and determining the resonant frequency and a Q-factor from monitoring the voltage. - View Dependent Claims (11, 12, 13, 14, 15)
-
-
16. A wireless power transmitter, comprising:
-
means for charging a capacitor in a resonant circuit that includes the capacitor series coupled with a transmit coil between a first node and a second node, the means for charging the capacitor coupled to a third node between the capacitor and the transmit coil; means coupled to the first node and the second node for driving the resonant circuit to transmit wireless power and to ground the first node and the second node during a Q-factor determination, means for sampling a voltage across the capacitor at the third node as a function of time; means for controlling coupled to the means for charging the capacitor, the means coupled to the first node and the second node, and the means for sampling, wherein the means for controlling provides wireless power by controlling the means coupled to the first node and the second node to drive current through the transmit coil, and wherein the means for controlling determines a Q-factor by controlling the means coupled to the first node and the second node to ground the second node and disconnect the first node, then controlling the means for charging to charge the capacitor, then, when the capacitor is charged, controlling the means coupled to the first node and the second node to ground the first node and receiving operating the and wherein the means for sampling the voltage samples data while the first node and the second node are grounded to provide data to determine the Q-factor; wherein the means for controlling includes a means for determining a resonant frequency of the resonant circuit from the voltage sampled by the means for sampling; and wherein the means for controlling includes means for determining a Q-factor from the voltage sampled by the means for sampling. - View Dependent Claims (17)
-
Specification