Fault managed power method for AC powering systems
Techniques for alternating current (AC) powering methods deployed at a power transmitter and a power receiver for line fault detection. AC power is applied to a pair of lines at a power transmitter to transmit the AC power to a power receiver. An occurrence of a predetermined characteristic of an AC voltage waveform or an AC current waveform is detected. The AC power is disconnected from the pair of lines upon detecting occurrence of the predetermined characteristic. Fault detection is performed during a safety check time window upon disconnecting the AC power from the pair of lines. The AC power is reconnected to the pair of lines when a fault is not detected from the fault detection during the safety check time window, and the AC power is maintained disconnected from the pair of lines when a fault is detected during the safety check time window.
1 . A method comprising:
applying alternating current (AC) power to a pair of lines at a power transmitter to transmit the AC power to a power receiver, the AC power comprising an AC voltage waveform and an AC current waveform;
detecting occurrence of a predetermined characteristic of the AC voltage waveform or the AC current waveform;
disconnecting the AC power from the pair of lines upon detecting occurrence of the predetermined characteristic of the AC voltage waveform or the AC current waveform;
performing a fault detection during a safety check time window upon disconnecting the AC power from the pair of lines; and
reconnecting the AC power to the pair of lines when a fault is not detected from the fault detection during the safety check time window, and maintaining the AC power disconnected from the pair of lines when a fault is detected during the safety check time window.
2 . The method of claim 1 , wherein the detecting and the disconnecting are performed at the power transmitter.
3 . The method of claim 1 , wherein the predetermined characteristic is a crossing point of the AC voltage waveform or the AC current waveform.
4 . The method of claim 3 , wherein the crossing point is a zero-crossing point of the AC voltage waveform or the AC current waveform, or a root mean squared (RMS) level crossing point of the AC voltage waveform or the AC current waveform.
5 . The method of claim 4 , further comprising:
applying a charging pulse of a predetermined time duration to the pair of lines after disconnecting the AC power from the pair of lines,
wherein the safety check time window begins after termination of the charging pulse.
6 . The method of claim 1 , wherein the predetermined characteristic is a phase offset with respect to a reference point of the AC voltage waveform or the AC current waveform.
7 . The method of claim 6 , wherein the phase offset is selected so that the disconnecting is performed when the AC voltage waveform is at a level to charge the pair of lines prior to performing the fault detection during the safety check time window.
8 . The method of claim 7 , wherein the phase offset is selected so that the disconnecting and the performing the fault detection are performed when the AC voltage waveform is rising and reaching a peak, and the fault detection is completed before the AC current waveform becomes non-zero.
9 . The method of claim 6 , wherein the phase offset is selected so that the disconnecting and the performing the fault detection are performed when the AC voltage waveform is falling from a peak and the AC current waveform crosses zero.
10 . The method of claim 6 , further comprising adjusting a capacitance or inductance in a path of the pair of lines or at a load of the power receiver to induce the phase offset.
11 . The method of claim 10 , wherein adjusting comprises controlling an amount of capacitance or inductance that is applied to the path by a power factor adjustment circuit.
12 . The method of claim 1 , wherein the predetermined characteristic used to trigger the disconnecting and the performing fault detection is based on a type of fault detection to be performed on the pair of lines.
13 . The method of claim 1 , further comprising, at the power receiver:
receiving, via the pair of lines, the AC power including the AC voltage waveform or the AC current waveform;
detecting occurrence of the predetermined characteristic of the AC voltage waveform or the AC current waveform received by the power; and
disconnecting from the pair of lines upon detecting occurrence of the predetermined characteristic of the AC voltage waveform or the AC current waveform.
14 . An apparatus comprising:
an alternating current (AC) power source to provide AC power comprising an AC voltage waveform and an AC current waveform;
a pair of lines configured to carry the AC power from the AC power source;
a switch circuit connected to the pair of lines and configured to either connect the AC power to the pair of lines or disconnect the AC power from the pair of lines;
a detection circuit coupled to the pair of lines and to the switch circuit, wherein the detection circuit is configured to detect a predetermined characteristic of the AC voltage waveform or the AC current waveform and provide a control output to the switch circuit to cause the switch circuit to disconnect the AC power from the pair of lines for a period of time upon detecting the predetermined characteristic; and
a fault detector coupled to the pair of lines and to the switch circuit, wherein the fault detector is configured to perform a fault detection during a safety check time window after the switch circuit has disconnected the AC power from the pair of lines, wherein the fault detector is further configured to control the switch circuit to reconnect the AC power to the pair of lines when a fault is not detected during the safety check time window, and to maintain the AC power disconnected from the pair of lines when a fault is detected during the safety check time window.
15 . The apparatus of claim 14 , wherein the predetermined characteristic is a crossing point of the AC voltage waveform or the AC current waveform.
16 . The apparatus of claim 15 , wherein the crossing point is a zero-crossing point of the AC voltage waveform or the AC current waveform, or a root mean squared (RMS) level crossing point of the AC voltage waveform or the AC current waveform.
17 . The apparatus of claim 16 , further comprising a pulse generator circuit configured to apply a charging pulse of a predetermined time duration to the pair of lines after disconnecting the AC power from the pair of lines, wherein the safety check time window begins after termination of the charging pulse.
18 . The apparatus of claim 14 , wherein the predetermined characteristic is a phase offset with respect to a reference point of the AC voltage waveform or AC current waveform, wherein the phase offset is selected so that the switch circuit disconnects the AC power from the pair of lines when the AC voltage waveform is at a level to charge the pair of lines prior to the fault detector performing the fault detection during the safety check time window.
19 . The apparatus of claim 18 , wherein the phase offset is selected so that the switch circuit disconnects the pair of lines from the AC power and the fault detector performs the fault detection when the AC voltage waveform is rising and reaching a peak, and the fault detection is completed before the AC current waveform becomes non-zero.
20 . The apparatus of claim 18 , further comprising a power factor adjustment circuit configured to adjust a capacitance or inductance in a path of the pair of lines or at a load of a power receiver to induce the phase offset.
21 . An apparatus comprising:
an alternating current (AC) power source to provide AC power comprising an AC voltage waveform and an AC current waveform;
a pair of lines configured to carry the AC power from the AC power source;
a switch circuit connected to the pair of lines and configured to either connect the AC power to the pair of lines or disconnect the AC power from the pair of lines;
an analog-to-digital converter coupled to receive the AC voltage waveform and the AC current waveform carried on the pair of lines and to convert the AC voltage waveform and the AC current waveform to digital data; and
a processor coupled to the analog-to-digital converter and to the switch circuit, wherein the processor is configured to:
detect a predetermined characteristic of the AC voltage waveform or the AC current waveform based on the digital data and provide a control output to the switch circuit to cause the switch circuit to disconnect the AC power from the pair of lines for a period of time upon detecting the predetermined characteristic;
perform fault detection during a safety check time window after the switch circuit has disconnected the AC power from the pair of lines; and
control the switch circuit to reconnect the AC power to the pair of lines when a fault is not detected during the safety check time window, or control the switch circuit to maintain the AC power disconnected from the pair of lines when a fault is detected during the safety check time window.
22 . The apparatus of claim 21 , wherein the predetermined characteristic is a crossing point of the AC voltage waveform or the AC current waveform.
23 . The apparatus of claim 22 , wherein the crossing point is a zero-crossing point of the AC voltage waveform or the AC current waveform, or a root mean squared (RMS) level crossing point of the AC voltage waveform or the AC current waveform.
24 . The apparatus of claim 21 , wherein the predetermined characteristic is a phase offset with respect to a reference point of the AC voltage waveform or AC current waveform, wherein the phase offset is selected so that the switch circuit disconnects the AC power from the pair of lines when the AC voltage waveform is at a level to charge the pair of lines prior to the processor performing fault detection during the safety check time window.
25 . The apparatus of claim 24 , wherein the phase offset is selected so that the switch circuit disconnects the pair of lines from the AC power and the processor performs the fault detection when the AC voltage waveform is rising and reaching a peak, and the fault detection is completed before the AC current waveform becomes non-zero.
26 . The apparatus of claim 24 , further comprising a power factor adjustment circuit configured to adjust a capacitance or inductance in a path of the pair of lines or at a load of a power receiver to induce the phase offset.