Ground Fault Detection Architectures, Systems, Circuits, and Methods
A new approach to Ground Fault Detection and Interruption. The entire DC port is driven with a small-amplitude oscillation or modulation, and the power converter's controller tests for the presence of some version of that signal. If the detected oscillations are too small, either as a result of the GFDI fuse being blown, OR as a result of the DC port having too low of an impedance to ground (ground fault), the circuit detects that and causes the power converter to shut down.
1 . A method of operating a power converter, comprising the actions of:
a) performing power conversion to transfer power from a first port to a second port; and
b) also driving an additional signal, onto at least one wire of the second port, which has a magnitude much smaller than the power transferred in step a), and which contains AC energy; and
c) detecting whether the additional signal is propagating through to another wire of the second port.
2 . The method of claim 1 , wherein the second port is a DC port.
3 . The method of claim 1 , wherein the additional signal is a square wave.
4 . The method of claim 1 , wherein a single controller circuit operates a driver circuit to perform the driving action, and also performs the detection action itself.
5 . A power converter which implements the method of claim 1 .
6 . A method of ground fault detection, comprising the actions of:
driving an AC signal onto a line which carries a predominantly DC current; and
detecting whether the AC signal is propagating along with the DC current, without attenuation due to a blown fuse or a short to ground.
7 . A ground fault detection circuit which implements the method of claim 6 .
8 . The method of claim 6 , wherein the AC signal is a square wave.
9 . The method of claim 6 , wherein a single controller circuit operates a driver circuit to perform the driving action, and also performs the detection action itself.