Patent ID: 9608533
Date: 2017-03-28
CPC Classifications: H02M,H05B

Claim:
1. An apparatus to control an amount of current delivered from an AC power source to an electrical load, the apparatus comprising: a line terminal configured to be connected to the AC power source; a load terminal configured to be connected to the electrical load; a controllably conductive power switch in series electrical connection between the line terminal and the load terminal; and a switching circuit configured to provide phase control of the controllably conductive power switch so as to control the amount of current delivered to the electric load, wherein the switching circuit is also configured to automatically detect at least one of: wherein the switching circuit is further configured to: apply a control pulse to the controllably conductive power switch at a first firing angle during a first period of time; apply the control pulse to the controllably conductive power switch at a test firing angle during a subsequent, second period of time; sense whether the controllably conductive power switch remains conductive after application of the control pulse at the test firing angle; wherein if the controllably conductive power switch does not remain conductive, incrementing the test firing angle by a predetermined amount and repeating application of a control pulse during a further subsequent period of time and sensing whether the controllably conductive power switch remains conductive; and wherein if the controllably conductive power switch remains conductive, set the test firing angle as a firing angle limit.