Transistor inverter with saturable winding and series capacitor for forced switching

Claim 2

In an inverter circuit including switching transistors for connection to a direct voltage source for providing an alternating current voltage to a load and first and second driver transistors for controlling the conducting states of said switching transistors having a secondary drive winding connected between their bases, a primary drive winding connected to said source and said driver transistors so that the direction of current flow therethrough is switched when said driver transistors are switched, the improvement comprising: a. a capacitor and a secondary winding of a saturable reactor connected in series with each other and across the said secondary drive b. a primary winding of said saturable reactor connected to be responsive to the flow of current through the switching transistors and load of (in) the inverter circuit; and c. means providing charging and discharging paths for said capacitor to apply switching potentials to the nonconducting driver transistors to produce rapid and positive switching, said secondary winding being poled to provide charging current to said capacitor in the same direction as the base drive applied to the conducting one of said driver transistors, whereby said capacitor charges to a potential having a polarity to drive the nonconducting transistor into the conducting state, said secondary winding holding said potential off while unsaturated so that upon saturation of said saturable reactor, said capacitor discharges and applies base drive of the proper polarity to the nonconducting one of said driver transistors to switch the conducting states of said driver transistors.

Claim 3

An inverter circuit according to claim 1 wherein said primary winding of said saturable reactor is connected across the load.

Claim 4

An inverter circuit according to claim 1 in which said primary winding of said saturable reactor is connected across said primary winding of said saturable reactor is connected across said primary drive winding.

Claim 5

In a center-tapped transistor inverter including a center-tapped primary drive winding having means for connecting its center tap a first terminal of a direct current voltage source, first and second transistors having their emitter-collector circuits connected between ends of said primary drive winding and means for connecting to a second terminal of the direct current voltage source, a secondary drive winding connected between the bases of said transistors, the improvement comprising: a. a saturable reactor having a primary winding connected across said primary drive winding: b. a secondary winding of said saturable reactor and a capacitor both connected in series across said secondary drive winding, said secondary winding of said saturable reactor being poled to provide charging current to said capacitor in the same direction as drive current applied to the bases of said transistors by said secondary drive windings, whereby said capacitor charges to a potential having a polarity to drive the nonconducting one of said driver transistors into the conducting states, said secondary winding of said saturable reactor holding said potential off while in the unsaturated state so that upon saturation of the saturable reactor said capacitor discharges and applies base drive of the proper polarity to the nonconducting driver transistor to switch the conducting state of said driver transistors; and c. first and second diodes, said first diode being connected to complete a charging path for said capacitor including the base-emitter junction of said first transistor, and said second diode being connected to complete a charging path for said capacitor through the base-emitter junction of said second transistor.

Claim 6

In a center-tapped transistor inverter including a center-tapped primary drive winding having means for connecting its center tap a first terminal of a direct current voltage source, first and second transistors having their emitter-collector circuits connected between ends of said primary drive winding and means for connecting to a second terminal of the direct current voltage source, a secondary drive winding connected between the bases of said transistors, the improvement comprising: a. a saturable reactor having a primary winding connected across said primary drive winding: b. a secondary winding of said saturable reactor and a capacitor both connected in series across said secondary drive winding, said secondary winding of said saturable reactor being poled to provide charging current to said capacitor in the same direction as drive current applied to the bases of said transistors by said secondary drive windings, whereby said capacitor charges to a potential having a polarity to drive the nonconducting one of said driver transistors into the conducting states, said secondary winding of said saturable reactor holding said potential off while in the unsaturated state so that upon saturation of the saturable reactor said capacitor discharges and applies base drive of the proper polarity to the nonconducting driver transistor to switch the conducting state of said driver transistors; and c. first and second diodes, said first diode being connected to complete a charging path for said capacitor including the base-emitter junction of said first transistor, and said second diode being connected to complete a charging path for said capacitor through the base-emitter junction of said second transistor.

Claim 7

In a transistor inverter comprising first, second, third, and fourth transistors, first and second transistors having their means for connecting emitter-collector circuits connected in series between first and second terminals of a direct current voltage source, and third and fourth transistors having means for connecting their emitter-collector circuits connected in series between the terminals of the direct current voltage source, the improvement comprising: a primary drive winding connected for conduction in first and second directions in response to rendering said first and third and said second and fourth transistors conductive alternately; b. a first secondary drive winding connected between the bases of said first and third transistors, and second and third secondary drive windings respectively connected in the emitter-base circuits of said second and fourth transistors, said secondary drive windings being poled to simultaneously turn on said first and fourth transistors while biasing said second and third transistors off; c. a saturable reactor having a primary winding connected across said primary drive winding; d. a first secondary winding of said saturable reactor and a capacitor both connected in series across said first secondary drive winding, second and third secondary windings of said saturable reactor and second and third capacitors respectively connected in series with said second and third secondary windings of said saturable reactor across said second and third drive windings respectively, each secondary winding of said saturable reactor being poled to provide capacitor charging current in the same direction as drive current; and e. first, second, third and fourth diodes each connected across the emitter-base circuit of said first, second, third and fourth transIstors for completing charging and discharging paths for said capacitors.

Claim 8

In a transistor inverter comprising first, second, third, and fourth transistors, first and second transistors having their means for connecting emitter-collector circuits connected in series between first and second terminals of a direct current voltage source, and third and fourth transistors having means for connecting their emitter-collector circuits connected in series between the terminals of the direct current voltage source, the improvement comprising: a primary drive winding connected for conduction in first and second directions in response to rendering said first and third and said second and fourth transistors conductive alternately; b. a first secondary drive winding connected between the bases of said first and third transistors, and second and third secondary drive windings respectively connected in the emitter-base circuits of said second and fourth transistors, said secondary drive windings being poled to simultaneously turn on said first and fourth transistors while biasing said second and third transistors off; c. a saturable reactor having a primary winding connected across said primary drive winding; d. a first secondary winding of said saturable reactor and a capacitor both connected in series across said first secondary drive winding, second and third secondary windings of said saturable reactor and second and third capacitors respectively connected in series with said second and third secondary windings of said saturable reactor across said second and third drive windings respectively, each secondary winding of said saturable reactor being poled to provide capacitor charging current in the same direction as drive current; and e. first, second, third and fourth diodes each connected across the emitter-base circuit of said first, second, third and fourth transIstors for completing charging and discharging paths for said capacitors.