Power converting

Power conversion system includes power amplifiers that receive D.C. potentials from rectifying and filtering circuitry that direct couple the power amplifiers to the conventional A.C. power lines. An output transformer couples the power amplified signal to an output terminal. A feedback network couples the output terminal to one input of a signal combiner that has a reference input terminal for receiving a reference signal. An isolation amplifier couples the output of the signal combiner to the input of the power amplifiers. The isolation amplifier has a combining network that receives on one input a signal from the input terminal coupled through a high pass filter cascaded with a transformer coupled amplifying stage and on the other input from the input terminal through an optocoupler amplifying stage cascaded with a low pass filter. The power amplifiers comprise like class B amplifiers having substantially the same gain driving the primary of the output transformer. An attenuator imparts an attenuation to the output of the first amplifier that is the reciprocal of the amplifier gain and delivers the attenuated signal to the input of the second amplifier. Current shunts in series with a lead from the rectifiers and filters provide a signal representative of the current drawn by each of the class B amplifiers. For D.C. output, there is a precision diode and 600 Hz signal inverter that couples the output of the signal combining network with the isolation amplifier and a 600 Hz output transformer cascaded with a rectifier and filter that couples the output of the power amplifiers to the output terminal.

What is claimed is:

1. Power conversion apparatus comprising,

an input terminal for receiving A.C. power from a conventional power line,

power amplifying means for amplifying an input signal,

rectifying and filtering means for direct coupling said power amplifying means to said A.C. power input terminal for providing D.C. energy to said power amplifying means,

an output terminal,

output transformer coupling means for coupling said power amplifying means to said output terminal while providing D.C. isolation from said A.C. power input terminal,

a reference input terminal for receiving a signal for controlling the signal on said output terminal,

feedback means for providing a feedback signal,

combining means for combining a feedback signal from said feedback means with a signal on said reference input terminal to provide a combined signal,

and isolation amplifying means for coupling said combined signal to said power amplifying means while providing D.C. isolation for both said output terminal and said reference input terminal from said A.C. power input terminal.

wherein said isolation amplifying means comprises,

a signal input terminal,

a signal output terminal,

transformer coupled amplifying means,

an optocoupler amplifying means for providing D.C. isolation,

low pass filtering means for selectively transmitting spectral components below a predetermined cutoff frequency,

high pass filtering means for selectively transmitting spectral components above said cutoff frequency,

a combining network coupled to said output terminal having first and second inputs for providing an output signal representative of the combination of the signals on said first and second inputs,

means including said high pass filtering means and said transformer coupled amplifying means for coupling said input terminal to said first input,

and means including said optocoupler amplifying means and said low pass filtering means for coupling said signal input terminal to said second input,

whereby said optocoupler amplifying means and said transformer coupled amplifying means coact to provide D.C. isolation between said signal input terminal and said signal output terminal.

2. Power conversion apparatus comprising,

an input terminal for receiving A.C. power from a conventional power line,

power amplifying means for amplifying an input signal,

rectifying and filtering means for direct coupling said power amplifying means to said A.C. power input terminal for providing D.C. energy to said power amplfiying means,

an output terminal,

output transformer coupling means for coupling said power amplifying means to said output terminal while providing D.C. isolation from said A.C. power input terminal,

a reference input terminal for receiving a signal for controlling the signal on said output terminal,

feedback means for providing a feedback signal,

combining means for combining a feedback signal from said feedback means with a signal on said reference input terminal to provide a combined signal,

and isolation amplifying means for coupling said combined signal to said power amplifying means while providing D.C. isolation for both said output terminal and said reference input terminal from said A.C. power input terminal,

wherein said power amplifying means comprises,

first and second power amplifying means for providing an amplified signal connected in a bridge circuit,

said output transformer coupling means comprising an output transformer having primary winding means for receiving amplified signals from said first and second amplifying means and coupled thereto,

each of said first and second amplifying means having a power amplifier input and characterized by first and second gains,

means for coupling said combined signal to the input of said first amplifying means,

attenuating means characterized by a first attenuation coupling the output of said first amplifying means to the input of said second amplifying means,

the product of said first gain and said first attenuation being substantially equal to said second gain.

3. Power conversion apparatus in accordance with claim 2 and further comprising,

first and second shunt resistive means in series with the D.C. current path between said first and second amplifying means, respectively, for providing current feedback signals representative of the current drawn by said first and second amplifying means respectively.

4. Power conversion apparatus comprising,

an input terminal for receiving A.C. power from a conventional power line,

power amplifying means for amplifying an input signal,

rectifying and filtering means for direct coupling said power amplifying means to said A.C. power input terminal for providing D.C. energy to said power amplifying means,

an output terminal,

output transformer coupling means for coupling said power amplifying means to said output terminal while providing D.C. isolation from said A.C. power input terminal,

a reference input terminal for receiving a signal for controlling the signal on said output terminal,

feedback means for providing a feedback signal,

combining means for combining a feedback signal from said feedback means with a signal on said reference input terminal to provide a combined signal,

isolation amplifying means for coupling said combined signal to said power amplifying means while providing D.C. isolation for both said output terminal and said reference input terminal from said A.C. power input terminal,

inverting means for coupling said combined signal to said isolation amplifying means to provide a signal of a predetermined frequency having an amplitude representative of the D.C. component of said combined signal,

and said transformer coupling means comprises,

a transformer for transmitting the amplified signal of said power amplifying means at said predetermined frequency,

and rectifying and filtering means coupled to the output of said transformer for delivering a D.C. signal to said output terminal representative of the amplitude of said signal of predetermined frequency.

5. Power amplifying means comprising,

first and second power amplifying means for providing an amplified signal connected in a bridge circuit,

means for combining amplified signals from said first and second amplifying means,

each of said first and second amplifying means having a power amplifier input and characterized by first and second gains,

means for coupling an input signal to the input of said first amplifying means,

and attenuating means characterized by a first attenuation coupling the output of said first amplifying means to the input of said second amplifying means,

the product of said first gain and said first attenuation being substantially equal to said second gain.

6. Power amplifying means in accordance with claim 5 wherein said means for combining comprises an output transformer having primary winding means for receiving amplified signals from said first and second amplifying means and coupled thereto.