Anti–flickering power modulation for electrical loads

Abstract

A power modulation method (20) for the supply of an electrical load (30) connected by means of a switch (SSR) to a network (5) with alternating-current supply voltage (10), in which to said network (5) there are also connected other loads such as lighting sources (40), in which said method comprises the step of feeding (16) said load (30) over time alternately with a first percentage power value (V1) and a second percentage power value (V2), i.e., with two percentage power values (V1, V2) defined with respect to the total alternating-current supply voltage (10) considered, obtaining a resultant average power (VM) intermediate between the two selected percentage power values (V1, V2), in which said method comprises the step of using the two different percentage power values (V1, V2) for time periods of different length, in which said method comprises the step of defining at least one of the two percentage power values (V1, V2) by means of a fixed on / off repetition scheme (22) of said switch (SSR) which, when switched off, prevents the passage of the half-15waves of the alternating-current supply voltage (10) to the load (30), wherein the fixed repetition scheme (22) defines, within a time period, how many and which half-waves are switched on and how many and which are switched off, in which said method comprises the step of selecting said fixed repetition scheme (22) so as to keep balanced the number of positive half-waves and negative half-waves, so as not to unbalance the network (5), and in which said repetition scheme (22) works with complete half-waves, and in particular using an on / off command of said switch(SSR) in zero crossing mode, in which said method comprises the step of selecting said two percentage power values (V1, V2) and said repetition scheme (22) so as to generate a signal of resultant power (16) modulated in power to feed the load (30), in which said signal of resultant power (16) generates periodic disturbances on the network (5), caused by the fixed repetition scheme (22) and by the transition between the two percentage power values (V1, V2), at a frequency equal to or greater than 25Hz, preferably equal to or greater than 33 Hz, thereby obtaining a continuous adjustment of the power that minimizes the undesired flickering phenomenon on the other loads such as lighting sources (40).

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