Constant current power supply

Claim 2

A power supply for energizing a load in response to a given alternating waveform having successive rising and declining portions and slope reversal points Between each rising and declining portion and between each declining and rising portion, comprising rectifier means for responding to the power waveform for producing a unidirectional voltage, control means in said rectifier means for turning said rectifier means on and off, current sensing means at the output of said rectifier means for producing a value signal responsive to the value of the current emerging from said rectifier means, sweep circuit means for producing a periodic sweep signal having a given period timed to straddle the reversing points so that at least a part of the rising portion and declining portion occur during each period, said sweep circuit means varying within the period, comparator means responsive to said sweep circuit means and said current sensing means for comparing the momentary levels of the signals and connected to said control means for constraining said control means to turn on said rectifier means after each time one of the signals bears a predetermined relation to the other, said sweep circuit means producing a sweep signal which is substantially constant during each period before the reversal and changes continuously in a given direction during at least a part of the remainder of the period.

Claim 3

A supply as in claim 1, wherein said rectifier means include capacitor means and said control means include a thyristor.

Claim 4

A supply as in claim 1, wherein the sweep signal changes slowly after the reversal and thereafter faster for the remainder of the period.

Claim 5

A supply as in claim 3, wherein said rectifier means include capacitor means and said control means include a thyristor.

Claim 6

A supply as in claim 3, wherein said sweep circuit means produces a sweep signal after a reversal with a rate of change corresponding to the rate of change of the power waveform afer the reversal.

Claim 7

A supply as in claim 5, wherein said rectifier means includes a rectifier bridge and capacitor filter means.

Claim 8

A supply as in claim 6, wherein said control means form part of said bridge and include a thyristor.

Claim 9

A supply as in claim 7, wherein said bridge includes four arms two of which include respective thyristors and two of which include respective diodes.

Claim 10

A supply as in claim 7, wherein said bridge includes four arms two of which include respective thyristors and two of which include respective diodes.

Claim 11

A supply as in claim 3, wherein the sweep circuit means produces the sweep signal so that its value remains constant through one half period up to the reversal and rises slowly and thereafter faster for the remaining half period.

Claim 12

A supply as in claim 10, wherein said rectifier means include capacitor means and said control means include a thyristor.

Claim 13

A supply as in claim 3, wherein the signal produced by said sweep circuit means follows the portion of a full wave rectified sinusoid, having zero slopes and clamped at the zero slopes, which follows the zero slope.

Claim 14

A supply as in claim 12, wherein said rectifier means include capacitor means and said control means include a thyristor.

Claim 15

A supply as in claim 10, wherein the signal produced by the sweep circuit follows the rising portion of a positively-clamped negative-going full-wave rectified sinusoid.

Claim 16

A supply as in claim 14, wherein said rectifier means include capacitor means and said control means include a thyristor.

Claim 17

A supply as in claim 12, wherein said sweep circuit means has diode means for forming the clamped waveform, and switch means connected to said diode means for preventing generation of the portion of the full-wave rectified waveform prior to the zero slope.

Claim 18

A supply as in claim 16, wherein said rectifier means include capacitor means and said control means include a thyristor.

Claim 19

A supply as in claim 16, wherein said switch means shunts the portion of the full-wave rectified signal to ground and passes the remaining portion of the signal.

Claim 20

A supply as in claim 18, wherein said rectifier means include capaCitor means and said control means include a thyristor.

Claim 21

A supply as in claim 16, wherein said switch means includes a switch connected across said diode means and voltage generator means for turning said switch means on during the portion of the full-wave rectified signal prior to the zero slope and turning said switch means off during the portion of the full-wave rectified waveform after the zero slope.

Claim 22

A supply as in claim 20, wherein said voltage generator means includes second diode means for producing a full-wave rectified potential, shunt means connected across said full-wave rectified potential, clamping means for clamping the full-wave rectified potential so that the zero slope is at zero level and connecting it to said shunt means so as to turn on said shunt means at the zero slope of each full-wave rectified waveform.

Claim 23

A supply as in claim 21, wherein said shunt means includes a thyristor.

Claim 24

A supply as in claim 22, wherein said switch means includes a transistor and said thyristor is connected between the base and emitter of said transistor, said diode means being connected from collector to emitter of said transistor.

Claim 25

A supply as in claim 3, wherein said rectifier means includes a rectifier bridge and capacitor filter means, and wherein said control means forms part of said bridge and includes a transistor.

Claim 26

A supply as in claim 24, wherein said sweep circuit means has diode means for forming a negative-going positively-clamped full-wave rectified waveform, and switch means connected to said diode means for preventing generation of the declining portion of the full-wave rectified waveform.

Claim 27

A supply as in claim 25, wherein said switch means shunts the declining portion of the positively-clamped full-wave rectified waveform to ground and passes the remaining portion of the waveform.

Claim 28

A supply as in claim 25, wherein said switch means includes a switch connected across said diode means and voltage generator means for turning said switch means on during the declining portion of the positively-clamped full-wave rectified waveform and turning said switch means off during the ascending portion of the positively-clamped full-wave rectified waveform.

Claim 29

A supply as in claim 27, wherein said voltage generating means includes second diode means for producing a full-wave rectified potential, shunt means connected across said full-wave rectified potential, clamping means for clamping the full-wave rectified potential negatively and connecting it to said shunt means so as to turn on said shunt means at the peak of each full-wave rectified waveform.

Claim 30

A supply as in claim 28, wherein said shunt means includes a thyristor.

Claim 31

A supply as in claim 29, wherein said switch means includes a transistor and said thyristor is connected between the base and emitter of said transistor, said diode means being connected from collector to emitter of said transistor.

Claim 32

A supply as in claim 24, wherein said bridge includes four arms, two of said arms having respective thyristors connected therein and two of said arms having diodes connected therein, said thyristors being connected to the output of said comparator means.

Claim 33

A supply as in claim 24, wherein said bridge includes four arms, two of said arms having respective thyristors connected therein and two of said arms having diodes connected therein, said thyristors being connected to the output of said comparator means.

Claim 34

A power supply for energizing a load from a multiphase power source each of whose phases includes successive rising and descending portions with zero slope points between the rising and descending portions, comprising a plurality of rectifier means each responsive to the source for producing a unidirectional voltage from one phase, control means in each of said rectifier means for turning said rectifier means on and off, current-sensing means connected to the output of each rectifier means for producing a value signal responsive to the vaLue of currents emerging from each of said rectifier means, a plurality of sweep circuit means each for producing a sweep signal having a given period which straddles the zero slope points of each phase so as to occur at least in part during a rising and descending portion and varying within the period, a plurality of comparator means each responsive to one of said sweep circuit means in said current-sensing means for comparing the momentary levels of the signals and connecting to each of said control means for constraining said control means to turn on said rectifier means after each time one of said signals bears a predetermined relation to the other, said sweep circuit means producing a sweep signal during each period which is substantially constant before the zero slope point and changes continually in a given direction during at least a part of the remainder of the period.

Claim 35

A power supply for energizing a load from a multiphase power source each of whose phases includes successive rising and descending portions with zero slope points between the rising and descending portions, comprising a plurality of rectifier means each responsive to the source for producing a unidirectional voltage from one phase, control means in each of said rectifier means for turning said rectifier means on and off, current-sensing means connected to the output of each rectifier means for producing a value signal responsive to the vaLue of currents emerging from each of said rectifier means, a plurality of sweep circuit means each for producing a sweep signal having a given period which straddles the zero slope points of each phase so as to occur at least in part during a rising and descending portion and varying within the period, a plurality of comparator means each responsive to one of said sweep circuit means in said current-sensing means for comparing the momentary levels of the signals and connecting to each of said control means for constraining said control means to turn on said rectifier means after each time one of said signals bears a predetermined relation to the other, said sweep circuit means producing a sweep signal during each period which is substantially constant before the zero slope point and changes continually in a given direction during at least a part of the remainder of the period.

Claim 36

A supply as in claim 33, wherein each of said sweep circuit means produces a signal which first rises slowly after the zero slope point and thereafter faster for the remaining period of each cycle.

Claim 37

A supply as in claim 34, wherein each of said sweep circuit means produces a sweep signal after each zero slope point so that the rate of change corresponds to the rate of change of the source after a zero slope point.