Foreign object detection method and power system capable of detecting foreign object

A power system capable of detecting a foreign object, comprising:

• a power supplier side, which is configured to be coupled to a power receiver side through a cable which includes a positive power transmission line, a negative power transmission line, and a signal transmission line the power system being adapted to detecting whether a foreign object exists in the power receiver side, the power supplier side having a supplier transmission node and the power receiver side having a receiver transmission node, and the signal transmission line transmitting a communication signal between the supplier transmission node and the receiver transmission node the power supplier side including:
• a power converter configured to supply a supply voltage to the power receiver side according to a power supply control signal;
• a foreign object detection and control circuit configured to generate the power supply control signal for controlling the power converter, and the foreign object detection and control circuit being further configured to generate a foreign object detection and control signal according to a voltage at the supplier transmission node, for determining whether a foreign object exists in the power receiver side;
• and
• a pull-up circuit configured to adaptively adjust a level of a supply current which is supplied from the supplier transmission node to the power receiver side
• wherein the foreign object detection and control circuit generates the foreign object detection and control signal according to the voltage at the supplier transmission node by the following steps:
• (A) providing a low current to the supplier transmission node, and determining whether a voltage at the supplier transmission node is higher than or equal to a first voltage by the transmission voltage detection circuit, wherein the low current corresponds to a low level of the supply current;
• (B1) when the step (A) determines that the voltage at the supplier transmission node is higher than or equal to the first voltage, indicating that the power supplier side and the power receiver side are not properly coupled with each other, then, the next step being (B2);
• (B2) supplying the low current from the supplier transmission node to the power receiver side by the pull-up circuit;
• (C) when the step (A) determines that the voltage at the supplier transmission node is not higher than and not equal to the first voltage, determining that the power supplier side and the power receiver side are coupled with each other, then, supplying a high current from the supplier transmission node to the power receiver side, wherein the high current corresponds to a high level of the supply current, wherein the high current is higher than the low current;
• (D) when the power supplier side and the power receiver side are determined coupled with each other and the pull-up circuit supplies the high current from the supplier transmission node to the power receiver side, determining whether the voltage at the supplier transmission node is between a second voltage and a third voltage, wherein the first voltage is higher than the second voltage, the second voltage is higher than the third voltage, and the third voltage is higher than 0;
• (E) when the step (D) determines that the voltage at the supplier transmission node is between the second voltage and the third voltage, which confirms that the power supplier side and the power receiver side are properly coupled with each other, keeping supplying the high current from the supplier transmission node to the power receiver side by the pull-up circuit;
• (F1) when the step (D) determines that the voltage at the supplier transmission node is not between the second voltage and the third voltage, indicating that a foreign object exists, then, the next step being (F2);
• and
• (F2) stopping supplying the high current and changing to supplying the low current from the supplier transmission node to the power receiver side by the pull-up circuit, to avoid damaging or rusting the receiver side.

A foreign object detection method for detecting whether a foreign object exists in a power receiver side in a power delivery loop formed by a power supplier side and the power receiver side, wherein the power supplier side and the power receiver side are configured to be coupled with each other through a cable which includes a positive power transmission line, a negative power transmission line, and a signal transmission line the power supplier side having a supplier transmission node and the power receiver side having a receiver transmission node, and the signal transmission line transmitting a communication signal between the supplier transmission node and the receiver transmission node, the method comprising:

• providing a low current to the supplier transmission node;
• and
• determining whether the power receiver side is coupled to the power supplier side and whether a foreign object exists, and when the power receiver side is coupled to the power supplier side and no foreign object exists, changing to supplying a high current through the supplier transmission node, wherein the high current is higher than the low current;
• otherwise keeping supplying the low current to the supplier transmission node;
• wherein the step of determining whether the power receiver side is coupled to the power supplier side and whether a foreign object exists includes:
• (A) after providing the low current to the supplier transmission node, determining whether the voltage at the supplier transmission node is higher than or equal to a first voltage;
• (B1) when the step (A) determines that the voltage at the supplier transmission node is higher than or equal to the first voltage, indicating that the power supplier side and the power receiver side are not properly coupled with each other, then, the next step being (B2);
• (B2) supplying the low current from the supplier transmission node to the power receiver side;
• (C) when the step (A) determines that the voltage at the supplier transmission node is not higher than and not equal to the first voltage, determining that the power supplier side and the power receiver side are coupled with each other, then, supplying a high current from the supplier transmission node to the power receiver side, wherein the high current is higher than the low current;
• (D) when the power supplier side and the power receiver side are determined coupled with each other and the pull-up circuit supplies the high current from the supplier transmission node to the power receiver side, determining whether the voltage at the supplier transmission node is between a second voltage and a third voltage, wherein the first voltage is higher than the second voltage, the second voltage is higher than the third voltage, and the third voltage is higher than 0;
• (E) when the step (D) determines that the voltage at the supplier transmission node is between the second voltage and the third voltage, which confirms that the power supplier side and the power receiver side are properly coupled with each other, keeping supplying the high current from the supplier transmission node to the power receiver side;
• (F1) when the step (D) determines that the voltage at the supplier transmission node is not between the second voltage and the third voltage, indicating that a foreign object exists, then, the next step being (F2);
• and
• (F2) stopping supplying the high current and changing to supplying the low current from the supplier transmission node to the power receiver side, to avoid damaging or rusting the receiver side.