US Patent No. 10,117,302

ELECTRONIC DRIVER WITH ELECTRIC-LEAKAGE PROTECTION FOR LED LIGHTING


Patent No. 10,117,302
Issue Date October 30, 2018
Title Electronic Driver With Electric-leakage Protection For Led Lighting
Inventorship Chun Tung Lo, Hong Kong (HK)
Assignee AMPCO PRODUCTS LTD., Hong Kong (HK)

Claim of US Patent No. 10,117,302

1. An electronic driver for driving a light-emitting diode (LED) load comprising:a converter circuit for converting electrical power provided by a unipolar voltage source to an output current used for driving the LED load, the converter circuit including a local ground node for collecting the output current and an operating current drawn by the converter circuit to form a return current to be returned to the unipolar voltage source, the unipolar voltage source having a source-side ground node for receiving at least the return current;
two electrical contacts collectively for electrically connecting to an external voltage source and receiving electrical power therefrom, the received electrical power being used for powering the unipolar voltage source;
a series cascade of a current sensor and a solid-state switch, the series cascade connecting the source-side ground node and the local ground node such that the current sensor is used for measuring the return current; and
an electronic controller configured to execute a control process for controlling the solid-state switch to switch on and off, the control process comprising a test subprocess for testing whether the external voltage source is electrically connected to both the electrical contacts, the test subprocess comprising:
switching on the solid-state switch for a test duration so as to drive the converter circuit to operate during the test duration, wherein the test duration is selected to be not greater than a maximum test duration predetermined for avoiding a person to absorb from the external voltage source an energy greater than a pre-defined human-tolerable shock energy under a condition that the external voltage source is electrically connected to only one of the electrical contacts and the person accidentally touches another one of the electrical contacts;
obtaining, from the current sensor, a measured value of the return current observed during the test duration; and
determining whether the external voltage source is electrically connected to both the electrical contacts according to the measured return-current value;
the control process further comprising:
responsive to determining that the external voltage source is electrically connected to both the electrical contacts, switching on the solid-state switch so as to drive the LED load; and
responsive to determining that the external voltage source is not electrically connected to both the electrical contacts, switching off the solid-state switch for an idle period so as to isolate the converter circuit from the unipolar voltage source, and then repeating the test subprocess, wherein the idle period is selected such that an energy absorbed by the converter circuit during the test period is substantially dissipated during the idle period.