Solid-state electric circuit for reversing polarity

Claim 2

Apparatus of the character disclosed for controlling current through an instrumentality, comprising, a source of AC, power circuit means connected with the AC source and including the instrumentality, control circuit means connected with the AC source, rectifier means in the power circuit for converting the AC to DC and applying to the instrumentality, said rectifier means including a first pair and a second pair of back-to-back controllable rectifiers, transformer means including primaries in the control circuit means and secondaries in the power circuit means individually related to and controlling the respective back-to-back rectifiers, and means responsive to the transformer primaries in the control circuit means for thereby controlling the respective secondaries and thereby controlling the controllable rectifiers and interrupting circuit to the instrumentality, the control circuit means through said transformer means being operative for reducing the degree of magnetism in the instrumentality in a series of steps.

Claim 3

Apparatus according to claim 1 and including means in the control circuit means operative for alternately reversing the voltage applied to the instrumentality and reducing the value of the voltage in successive steps whereby to reduce the level of magnetism in the instrumentality to a value near zero.

Claim 4

Apparatus of the character disclosed for controlling current through an instrumentality, comprising power circuit means including the instrumentality, an AC source, rectifier means for converting the AC to DC and imposing it on the instrumentality whereby the instrumentality becomes magnetized, said rectifier means including a first pair of back-to-back SCR''s, transformer secondaries operative for controlling the energization of the SCR''s, a second pair of back-to-back SCR''s respectively associated with the first pair of SCR''s, control circuit means, transformer means in the apparatus, including a secondary operatively controlling each of the rectifier means and a primary related to each secondary, the rectifier means being so interrelated that the said pairs thereof are operative for imposing DC voltage in respectively opposite directions in the instrumentality, means in the control circuit for alternately energizing the pairs of primaries and therethrough the secondaries and the rectifier means, respectively, in a succession of steps in which the voltage is reversed in successive steps, and means for reducing the value of the voltage in each successive step.

Claim 5

Apparatus of the character disclosed for controlling current through an instrumentality, comprising power circuit means including the instrumentality, an AC source, rectifier means for converting the AC to DC and imposing it on the instrumentality whereby the instrumentality becomes magnetized, said rectifier means including a first pair of back-to-back SCR''s, transformer secondaries operative for controlling the energization of the SCR''s, a second pair of back-to-back SCR''s respectively associated with the first pair of SCR''s, control circuit means, transformer means in the apparatus, including a secondary operatively controlling each of the rectifier means and a primary related to each secondary, the rectifier means being so interrelated that the said pairs thereof are operative for imposing DC voltage in respectively opposite directions in the instrumentality, means in the control circuit for alternately energizing the pairs of primaries and therethrough the secondaries and the rectifier means, respectively, in a succession of steps in which the voltage is reversed in successive steps, and means for reducing the value of the voltage in each successive step.

Claim 6

Apparatus according to claim 3 and including full wave rectifier means operatively connected with the instrumentality and second transformer means connected in parallel with the full wave rectifier means and operative for controlling the first mentioned pairs of transformer means, whereby to reduce the voltage imposed on the instrumentality in the successive steps.

Claim 7

Apparatus according to claim 3 and including capacitor means controlled by the instrumentality whereby to charge the capacitor means according to the value of the magnetism in each of said steps, whereby to correspondingly control the control circuit to impose progressively lesser values of voltage on the instrumentality.

Claim 8

Apparatus according to claim 4 and including second transformer means operatively responsive to the value of magnetism in the instrumentality for producing controlling current in the control circuit means, and further including capacitor means in the control circuit means having capacity sufficient to be charged during each step to a condition whereby to be operative for opposing the current produced in said second transformer means and thereby reduce the value of the current in successive steps.

Claim 9

Apparatus according to claim 6 and including relay means operative for establishing subcircuits for imposing respectively opposite polarity on the instrumentality, and wherein the control circuit includes means for delaying effective operative control condition of the respective relay means.

Claim 10

Apparatus according to claim 3 and including circuitry having first condition in which it is operative for controlling a continuous operation, the means for the step operation is deenergized, and having manually controlled means for placing the circuitry in second condition in which the means for the step operation is activated.

Claim 11

Apparatus according to claim 3 and including manually operative means for interrupting the means for reversing the voltage in said successive steps, and including means for fast pulsing for reducing the level of magnetism in the instrumentality in two steps.

Claim 12

Apparatus of the character disclosed for controlling the energization and magnetization of an object, comprising an AC source, power circuit means connected with the AC source and including said object, rectifier means for converting the AC to DC and imposing it on the object, said rectifier means including a first and a second pair of back-to-back SCR''s respectively opposed, a first and a second pair of transformer secondaries controlling the respective SCR''s, a full wave rectifier connected with the object and in series with the SCR''s, a second transformer means having a primary connected across the full wave rectifier, the apparatus also including control circuit means which includes a first and a second pair of transformer primaries operatively associated with respective ones of the first pair and second pair of secondaries, the control circuit means having a first active conDition, including means operative in its first active position or energizing the first pair of transformer primaries in constant condition whereby to impose DC in a predetermined direction on the object, the control circuit means including a first secondary associated with the first transformer, capacitor means energized by said second transformer secondary, a first and a second relay operatively associated with the first and second pair of first transformer primaries, means for alternately energizing the first and second relay for correspondingly energizing the first and second pairs of transformer primaries for correspondingly reversing the voltage in the object, a third relay having contacts respectively associated with the first and second relays in opposite senses and operative when energized, and deenergized, for correspondingly energizing the first and second relays, control rectifier means in the control circuit means, the second transformer secondary and said capacitor means being operative for imposing control on the control rectifier means, the control rectifier means being operative for imposing control on the first and second relays, the capacitor means being energized by current established in said second transformer means and being opposed thereto, and the capacitor means having such capacity that upon discharge thereof it is energized, said control rectifier means in opposition to the current established in said second transformer secondary whereby to control the energization of said first and second relays alternately in a succession of steps and operative for correspondingly reducing the level of magnetism in the object in successive steps to a final step in which the level of magnetism is substantially zero.

Claim 13

Apparatus of the character disclosed for controlling the energization and magnetization of an object, comprising an AC source, power circuit means connected with the AC source and including said object, rectifier means for converting the AC to DC and imposing it on the object, said rectifier means including a first and a second pair of back-to-back SCR''s respectively opposed, a first and a second pair of transformer secondaries controlling the respective SCR''s, a full wave rectifier connected with the object and in series with the SCR''s, a second transformer means having a primary connected across the full wave rectifier, the apparatus also including control circuit means which includes a first and a second pair of transformer primaries operatively associated with respective ones of the first pair and second pair of secondaries, the control circuit means having a first active conDition, including means operative in its first active position or energizing the first pair of transformer primaries in constant condition whereby to impose DC in a predetermined direction on the object, the control circuit means including a first secondary associated with the first transformer, capacitor means energized by said second transformer secondary, a first and a second relay operatively associated with the first and second pair of first transformer primaries, means for alternately energizing the first and second relay for correspondingly energizing the first and second pairs of transformer primaries for correspondingly reversing the voltage in the object, a third relay having contacts respectively associated with the first and second relays in opposite senses and operative when energized, and deenergized, for correspondingly energizing the first and second relays, control rectifier means in the control circuit means, the second transformer secondary and said capacitor means being operative for imposing control on the control rectifier means, the control rectifier means being operative for imposing control on the first and second relays, the capacitor means being energized by current established in said second transformer means and being opposed thereto, and the capacitor means having such capacity that upon discharge thereof it is energized, said control rectifier means in opposition to the current established in said second transformer secondary whereby to control the energization of said first and second relays alternately in a succession of steps and operative for correspondingly reducing the level of magnetism in the object in successive steps to a final step in which the level of magnetism is substantially zero.