Engine-driven generator

A method of operating an engine-driven generator so as to generate an alternating potential having a frequency and voltage that remain within predetermined limits despite varying loads, said methods comprising the steps of;

• turning an alternator with an engine to develop a first alternating potential having a frequency and no-load voltage related directly to the engine speed;
• converting said first alternating potential into a second alternating potential of lower frequency than said first alternating potential wherein each positive polarity half-cycle of said second alternating potential consists essentially of an integral number of positive polarity half-cycles of said first alternating potential, and wherein each negative polarity half-cycle of said second alternating potential consists essentially of an equal number of negative polarity half-cycles of said first alternating current;
• and
• increasing said integral number with increasing frequency of said second alternating potential so that the frequency of said first alternating potential remains within predetermined upper and lower frequency limits.

An engine-driven generator comprising:

• an internal combustion engine;
• an alternator coupled to said engine and operable to develop a first alternating potential having a frequency and no-load voltage dependent on the speed of said engine;
• means for converting said first alternating potential into a second alternating potential wherein said second alternating potential is of a lower frequency than said first alternating potential and wherein said second alternating potential comprises a predetermined number of positive polarity half-cycles of said first alternating potential followed by an equal number of negative polarity half-cycles of said first alternating potential;
• means for increasing or decreasing said predetermined number in accordance with the frequency of said first alternating potential so as to maintain the frequency of said second alternating potential between pre-established upper and lower frequency limits;
• and
• means for deleting from said second alternating current selected ones of said positive and negative polarity half-cycles of said first alternating current so as to maintain the RMS voltage of said second alternating current between pre-established upper and lower voltage limits.

A method of operating an engine-driven generator so as to generate an alternating potential having a frequency and voltage that remain within predetermined limits despite varying loads, said method comprising the steps of:

• turning an alternator with an engine to develop a first alternating potential having a frequency and no-load voltage related directly to the engine speed;
• converting said first alternating potential into a second alternating potential of lower frequency than said first alternating potential wherein each positive polarity half-cycle of said alternating potential comprises a predetermined number of positive polarity half-cycles of said first alternating potential, and wherein each negative polarity half-cycle of said second alternating potential comprises an equal number of negative polarity half-cycles of said first alternating current;
• increasing said predetermined number with increasing frequency of said second alternating potential so that the frequency of said first alternating potential remains within predetermined upper and lower frequency limits;
• and
• varying the engine speed so as to maintain an integral number of said half-cycles of said first alternating potential in each of said half-cycles of said second alternating potential and to maintain the RMS voltage of said second alternating potential between said predetermined upper and lower voltage limits.

An engine-driven generator comprising:

• an internal combustion engine;
• an alternator coupled to said engine, said alternator developing an alternator current having a frequency and no-load voltage dependent on the speed of said engine;
• a controlled bridge coupled to said alternator operable to convert said alternator current to a series of pulses of selectable polarity, each of said pulses comprising substantially one half-cycle of said alternator current;
• and
• a system control coupled to said controlled bridge operable to control the polarity of said pulses and thereby arrange said pulses into alternating sequences of opposite polarity, each of said sequences containing substantially exactly an integral number of said pulses;
• said system control being further operable to vary said integral number so as to maintain the cyclical alternating rate of said alternating sequences substantially between pre-established upper and lower frequency limits.