Fast response stepped-wave switching power converter circuit

Claim 2

A fast response stepped-wave power converter circuit responsive to a variable input electrical reference signal comprising a plurality of inverter modules each having at least two discrete output voltages, means for connecting together said inverter modules as a stepped-wave inverter so that the composite stepped-wave output voltage is the algebraic sum of the individual module output voltages, and control and logic means for selectively switching said inverter modules to produce the composite output voltage as a desired function of the reference signal, wherein said control and logic means comprises means for generating control band limits that are effectively arranged about the reference signal and have instantaneous values differing from the instantaneous reference signal by predetermined amounts, means for effectively comparing the instantaneous values of the composite output voltage and each control band limit, and logic means for deriving gating signals to change the individual output voltage of at least one inverter module and produce a step change in the composite stepped-wave output voltage when the instantaneous composite output voltage substantially equals a value related to the control band limits.

Claim 3

A circuit according to claim 1 wherein all of said inverter modules are identical and have individual output voltages of equal magnitude with positive and negative polarity, and said logic means derives gating signals to change the output of one or more inverter modules when the instantaneous composite output voltage substantially equals at least one control band limit.

Claim 4

A circuit according to claim 1 Wherein said inverter modules are unequal and include a plurality of identical inverter modules that have individual output voltages of equal magnitude with positive and negative polarity, and at least one inverter module that has individual output voltages of equal magnitude and opposite polarity that are a multiple of the individual output voltages of the identical modules, and wherein said logic means derives gating signals to change the output of one or more inverter modules when the instantaneous composite output voltage substantially equals at least one control band limit.

Claim 5

A circuit according to claim 2 wherein each of said inverter modules has a third discrete output voltage of 0 volts.

Claim 6

A circuit according to claim 2 wherein the magnitude of the total voltage between the two control band limits is approximately equal to the magnitude of the individual output voltages of the identical inverter modules.

Claim 7

A circuit according to claim 1 wherein said control band limits are symmetrical about the reference signal and each differs from the instantaneous reference signal by a constant value, and said logic means derives gating signals to change the output of one or more inverter modules when the instantaneous composite output voltage departs from the range between the two control band limits.

Claim 8

A circuit according to claim 1 wherein all of said inverter modules have individual output voltages of equal magnitude, or an integer multiple thereof, and opposite polarity, said control band limits are symmetrical about the reference signal and each differs from the instantaneous reference signal by a constant voltage, and said logic means derives gating signals to change the output of one or more inverter modules when the instantaneous composite output voltage is substantially equal to either control band limit voltage.

Claim 9

A circuit according to claim 1 wherein all of said inverter modules have individual output voltages of equal magnitude, or an integer multiple thereof, and opposite polarity, and said connecting means directly connects the output terminals of said inverter modules in series with one another.

Claim 10

A circuit according to claim 1 wherein all of said inverter modules have individual output voltages of equal magnitude, or an integer multiple thereof, and opposite polarity, and said connecting means connects together the input power terminals of said inverter modules in parallel with one another, and further including output transformer means comprising an output transformer for each inverter module including a primary winding coupled between the output terminals of each module, the secondary windings of said output transformers being connected together in series.

Claim 11

A fast response stepped-wave power amplifier circuit for amplifying a variable input electrical reference signal comprising a plurality of solid state inverter modules each including at least a pair of solid state switching devices controlled to provide at least two different output voltages of equal magnitude and opposite polarity, means for connecting together said inverter modules as a stepped-wave inverter so that the composite stepped-wave output voltage is the algebraic sum of the individual module output voltages, and control and logic means for selectively switching said inverter modules to produce the composite output voltage as a stepped-wave reproduction of the input reference signal, wherein said control and logic means comprises means for generating control band limits that are effectively arranged about the reference signal and have instantaneous voltage values such that the differences between the instantaneous reference signal and each control band limit have respectively constant predetermined voltage magnitudes, means for comparing a signal that is a function of the instantaneous output voltage with each control band limit, and logic means for deriving gating signals for the solid state switChing devices in said inverter modules to change the individual output voltage of at least one inverter module and produce a step change in the composite output voltage when the signal that is a function of the instantaneous output voltage substantially equals at least one control band limit.

Claim 12

A fast response stepped-wave power amplifier circuit for amplifying a variable input electrical reference signal comprising a plurality of solid state inverter modules each including at least a pair of solid state switching devices controlled to provide at least two different output voltages of equal magnitude and opposite polarity, means for connecting together said inverter modules as a stepped-wave inverter so that the composite stepped-wave output voltage is the algebraic sum of the individual module output voltages, and control and logic means for selectively switching said inverter modules to produce the composite output voltage as a stepped-wave reproduction of the input reference signal, wherein said control and logic means comprises means for generating control band limits that are effectively arranged about the reference signal and have instantaneous voltage values such that the differences between the instantaneous reference signal and each control band limit have respectively constant predetermined voltage magnitudes, means for comparing a signal that is a function of the instantaneous output voltage with each control band limit, and logic means for deriving gating signals for the solid state switChing devices in said inverter modules to change the individual output voltage of at least one inverter module and produce a step change in the composite output voltage when the signal that is a function of the instantaneous output voltage substantially equals at least one control band limit.

Claim 13

A circuit according to claim 10 wherein said solid state inverter modules are bridge inverter modules having two pairs of solid state switching devices arranged as a bridge circuit to provide an additional output voltage of 0 volts, all of said inverter modules being identical with the exception of at least one module having individual output voltages that are an integer multiple of the individual output voltages of the identical modules, and wherein said connecting means directly connects the output terminals of said inverter modules in series with one another.

Claim 14

A circuit according to claim 11 wherein said means for comparing the signal that is a function of the instantaneous composite output voltage with each control band limit comprises a summing circuit for continuously deriving the error voltage between the instantaneous reference signal and the stepped-wave output voltage, and an analog-to-digital compare and conversion circuit for comparing the error voltage with each control band limit and determining the information required to produce the proper change in composite output voltage.

Claim 17

The method according to claim 13 wherein the switching of at least one inverter module occurs when the signal that is a function of the instantaneous composite output voltage substantially equals either one of the control band limit signals.

Claim 18

The method according to claim 13 wherein the switching of at least one inverter module occurs when the signal that is a function of the instantaneous composite output voltage substantially equals one of the control band limit signals depending on the slope of the reference signal.

Claim 19

The method according to claim 14 wherein said control band limit signals and said reference signal are voltage signals.

Claim 20

The method according to claim 13 wherein the signal that is a function of the instantaneous stepped-wave output voltage is compared with the control band limit signals by the steps of deriving an indication of the instantaneous stepped-wave output voltage, obtaining the error voltage between the instantaneous reference signal and the indication of the instantaneous output voltage, comparing the error voltage with the control band limit signals and generating a compare output when the error voltage substantially equals either control band limit signal, and utilizing the compare outputs in an analog-to-digital conversion circuit to determine the information rEquired to switch the inverter modules.

Claim 21

The method according to claim 13 wherein the signal that is a function of the instantaneous stepped-wave output voltage is compared with the control band limit signals by the steps of deriving an indication of the instantaneous output current in the form of a voltage signal proportional to the output current, obtaining the error voltage between the instantaneous reference signal and the indication of the instantaneous output current, comparing the error voltage with the control band limit signals and generating a compare output when the error voltage substantially equals either control band limit, and utilizing the compare outputs in an analog-to-digital conversion circuit to determine the information required to switch the inverter modules.