Electronic converter with regulated output current and frequency

Claim 2

A converter for generating a substantially constant current over widely varying load conditions, comprising: a free-running, two-transformer inverter utilizing current feedback; means, response to the free-running, two-transformer inverter, for generating a frequency synchronized switching voltage having a duty cycle which is proportional to the output current from said inverter; a switching regulator, responsive to the switching voltage for switching a supply voltage; and means for filtering the switched supply voltage to provide a variable dc supply voltage to said inverter which tends to oppose changes in the output current thereof; whereby the output current and the frequency of the inverter remain substantially constant over widely varying load conditions.

Claim 3

A dc to dc converter, for generating a substantially constant current over widely varying load conditions, comprising: a free-running, two-transformer push-pull inverter having a saturating driver transformer utilizing current feedback, and a non-saturating output transformer; means for generating a dc control voltage which varies in proportion to the current in said non-saturating output transformer; means responsive to the switched output voltage of said two-transformer push-pull inverter, for generating a sawtooth voltage of substantially constant amplitude; drive circuit means, responsive to the sawtooth voltage superimposed on said dc control voltage, for generating a switching voltage having a variable duty cycle; a switching regulator, responsive to said switching voltage, for switching a supply voltage; means for filtering the switched supply voltage to provide a variable dc supply voltage to said inverter which opposes changes in the output current of the non-saturating output transformer; and means for rectifying and filtering the output of said non-saturating output transformer to provide a substantially constant direct current output over widely varying load conditions; whereby the frequency of the inverter also remains substantially constant over said conditions.

Claim 4

A dc to dc converter, for generating a substantially constant current over widely varying load conditions, comprising: a free-running, two-transformer push-pull inverter having a saturating driver transformer utilizing current feedback, and a non-saturating output transformer; means for generating a dc control voltage which varies in proportion to the current in said non-saturating output transformer; means responsive to the switched output voltage of said two-transformer push-pull inverter, for generating a sawtooth voltage of substantially constant amplitude; drive circuit means, responsive to the sawtooth voltage superimposed on said dc control voltage, for generating a switching voltage having a variable duty cycle; a switching regulator, responsive to said switching voltage, for switching a supply voltage; means for filtering the switched supply voltage to provide a variable dc supply voltage to said inverter which opposes changes in the output current of the non-saturating output transformer; and means for rectifying and filtering the output of said non-saturating output transformer to provide a substantially constant direct current output over widely varying load conditions; whereby the frequency of the inverter also remains substantially constant over said conditions.

Claim 5

A dc to dc converter as defined in claim 2 in which the drive circuit means comprises: a switching transistor in which the sawtooth voltage is ac coupled and the dc control voltage is dc coupled thereto, so that a change in the level of the dc control voltage alters the portion of the sawtooth voltage which causes the switching transistor to conduct, thereby altering said duty cycle.

Claim 6

A dc to dc converter as defined in claim 2 in which the means for generating a dc control voltage comprises: a resistive bridge in which one pair of opposed ends is connected across a source of reference voltage and the other pair of opposed ends is connected tO the inputs of a differential amplifier, and the current in said non-saturating output transformer is introduced across one arm of said bridge.

Claim 7

A dc to dc converter as defined in claim 4 which additionally includes an over-voltage limiter comprising: means for generating an over-voltage control signal when the dc output voltage exceeds a predetermined value; and means for introducing said over-voltage control signal to the arm of said bridge opposed said one arm.

Claim 8

A converter for generating a substantially constant current over widely varying load conditions, comprising: a free-running inverter utilizing current feedback; switching regulator means, responsive to the output current from the free-running inverter, for switching a supply voltage so that the duty cycle thereof opposes changes in the output current of said free-running inverter; and means for filtering the switched supply voltage to provide a variable dc supply voltage to said inverter; whereby the output current and the frequency of the inverter remain substantially constant over widely varying load conditions.

Claim 9

A converter for generating a substantially constant current over widely varying load conditions, comprising: a free-running inverter utilizing current feedback; switching regulator means, responsive to the output current from the free-running inverter, for switching a supply voltage so that the duty cycle thereof opposes changes in the output current of said free-running inverter; and means for filtering the switched supply voltage to provide a variable dc supply voltage to said inverter; whereby the output current and the frequency of the inverter remain substantially constant over widely varying load conditions.