Ac-to-ac power regulation circuits having low e.m.i. and shorted load protection

Claim 2

In an AC power line circuit, having a power regulating switch means comprising a power transistor connected across a diode bridge to be conductive bi-directionally in said line circuit, the method of regulating the power output, comprising: a. establishing said power transistor in a conductive condition substantially coincident with the occurrence of zero current phase of the line power each half-cycle of the line power; b. developing an input control voltage as a function of the regulated power desired for the load; c. controlling the base bias of said power transistor in response to said input control voltage to render said power transistor non-conductive at a time during each half-cycle of line power when the phase of the line current is more than zero current phase and a substantial line voltage is across said power regulating switch means; and d. capacitatively filtering the power output applied to the load to minimize changing current in the line and load and thereby reduce generation of electromagnetic interference.

Claim 3

An AC-to-AC power regulation circuit for use in a line circuit developing from an unregulated AC input a regulated AC output responsive to an externally derived input control voltage indicative of regulated power desired for a load connected to said output, said power regulation circuit comprising: a. zero cross detection means generating a synchronizing pulse substantially coincident with each occurrence of zero current phase of the input AC power; b. variable width pulse generator means developing a pulsed wave output having a voltage excursion each half-cycle of said input AC power which is substantially coincident with each synchronization pulse from said zero cross detection means and a second pulsed wave output having a voltage excursion each half-cycle of said input AC power which is responsive to the level of said input control voltage; c. power regulating switch means including a power transistor connected to operate bi-directionally in series with said line circuit and the output load; d. power transistor bias control circuitry responsive to said first and second pulsed wave outputs to render said power transistor conductive each occurrence of the said first voltage excursion and non-conductive each occurrence of the said second voltage excursion; and e. capacitative line filtering means in the line output load circuit acting to minimize change in current in the line and load and thereby reduce generation of electromagnetic interference therein.

Claim 4

An AC-to-AC power regulation circuit for use in a line circuit developing from an unregulated AC input a regulated AC output responsive to an externally derived input control voltage indicative of regulated power desired for a load connected to said output, said power regulation circuit comprising: a. zero cross detection means generating a synchronizing pulse substantially coincident with each occurrence of zero current phase of the input AC power; b. variable width pulse generator means developing a pulsed wave output having a voltage excursion each half-cycle of said input AC power which is substantially coincident with each synchronization pulse from said zero cross detection means and a second pulsed wave output having a voltage excursion each half-cycle of said input AC power which is responsive to the level of said input control voltage; c. power regulating switch means including a power transistor connected to operate bi-directionally in series with said line circuit and the output load; d. power transistor bias control circuitry responsive to said first and second pulsed wave outputs to render said power transistor conductive each occurrence of the said first voltage excursion and non-conductive each occurrence of the said second voltage excursion; and e. capacitative line filtering means in the line output load circuit acting to minimize change in current in the line and load and thereby reduce generation of electromagnetic interference therein.

Claim 5

A power regulation circuit according to claim 2, wherein said power regulating switch means comprises a power transistor and four rectifier diodes connected in bridge circuit with said power transistor and in series with the line.

Claim 6

A power regulation circuit according to claim 3, wherein said capacitative line filtering means is connected across the rectifier bridge.

Claim 7

A power regulation circuit according to claim 4, wherein the output from the rectifier bridge is coupled to the load through step-down transformer means.

Claim 8

A power regulation circuit according to claim 2, wherein the power transistor bias control circuitry includes control transistor means in circuit with said power transistor means to be non-conductive when the control transistor means is conductive and to be conductive when the control transistor is non-conductive, said control transistor means being responsive to said second pulsed wave output to be rendered conductive by the said voltage excursion thereof.

Claim 9

A power regulation circuit according to claim 6, wherein said bias control circuitry includes impedance means coupled to the collector means of the power transistor and supplying base bias to saturate a control transistor whenever the collector current of the power transistor is excessive and under such condition rendering the power transistor non-conductive, thereby providing protection for the power regulating circuit in the event of load short circuit.

Claim 10

In an AC-to-AC regulated power supply circuit wherein an AC input is interrupted a variable amount each half-cycle to vary the power output in response to a DC control input variable independently of the power input and wherein the power interruption each half-cycle is obtained by power switch means coupled to the load to which the regulated power output is applied; the improvement comprising: a. turn-on pulse generation means developing a first series of voltage excursions at twice the AC power input frequency, b. turn-off pulse generation means developing a second series of voltage excursions at twice the AC power input frequency and related in phase to the said first series of voltage excursions in a manner determined by said DC control input, c. bridge type power switch means including a power transistor, and power transistor bias control circuitry responsive to the output of said turn-on pulse generation means to render such power transistor means conductive each half-cycle of the AC power input and responsive to the output of said turn-off pulse generation means to render such power transistor means non-conductive each half-cycle of the AC power input.

Claim 11

In an AC-to-AC regulated power supply circuit wherein an AC input is interrupted a variable amount each half-cycle to vary the power output in response to a DC control input variable independently of the power input and wherein the power interruption each half-cycle is obtained by power switch means coupled to the load to which the regulated power output is applied; the improvement comprising: a. turn-on pulse generation means developing a first series of voltage excursions at twice the AC power input frequency, b. turn-off pulse generation means developing a second series of voltage excursions at twice the AC power input frequency and related in phase to the said first series of voltage excursions in a manner determined by said DC control input, c. bridge type power switch means including a power transistor, and power transistor bias control circuitry responsive to the output of said turn-on pulse generation means to render such power transistor means conductive each half-cycle of the AC power input and responsive to the output of said turn-off pulse generation means to render such power transistor means non-conductive each half-cycle of the AC power input.