Voltage regulated capacitive discharge welding power supply

A highly regulated capacitive discharge resistance welder comprising:

• an alternating current source of charging electrical energy;
• energy storage capacitive means;
• error detector means for comparing the energy level of the energy storage means to a pre-selected level;
• first circuit means for supplying charging electrical energy to the capacitive means such that energy supply is a function of the difference between the energy level of the capacitive means and the pre-selected level;
• second circuit means responsive to the error detector means for shunting the charging electrical energy away from the capacitive means only during a portion of the cycle of the alternating current source signal when the energy level of the capacitive means reaches the pre-selected level, whereby storage of the energy above the pre-selected level is prevented, and whereby during any charging of the capacitor means no further current passes through the second circuit means beyond that provided in the remainder of the cycle of the alternating current source signal when the pre-selected level is reached;
• third circuit means responsive to the error detector means for initiating the supply of charging electrical energy by the first circuit means, and phasing forward the conduction angle of the charging electrical energy, when the energy level of the capacitive means drops below the pre-selected level, such that the source of charging electrical energy resupplies that amount of charge energy lost by the capacitive means due to leakage;
• and
• means for delivering the energy stored in the capacitive means to a pair of welding electrodes.