Forced voltage sharing in series-connected power inverters

Claim 2

In combination, a source of direct current, first and second inverters, each inverter having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, means for providing a sample of the AC output of one of said inverters, means for rectifying said sample to a direct current output, and means for feeding said direct current output to augment the DC input of the other inverter when the DC input of one inverter departs from a predetermined balance with respect to the other.

Claim 3

In combination, a source of direct current, first and second sine wave inverters coupled in series with each other and including serial-connected inductor Windings connected by way of switching means to said source of direct current, a capacitor connector to form a parallel resonant circuit with each of said inductor windings, means including a transformer having a primary winding coupled to the output of each serially connected inverter and a secondary winding coupled to an output circuit, means for sampling the alternating current output of said first inverter, means for rectifying said sampled alternating current to a direct current and feeding said direct current to the input of said second inverter, thereby to substantially balance the input voltages from said source of direct current to said first and second inverters.

Claim 4

In combination, a source of direct current, first and second sine wave inverters coupled in series with each other and including serial-connected inductor Windings connected by way of switching means to said source of direct current, a capacitor connector to form a parallel resonant circuit with each of said inductor windings, means including a transformer having a primary winding coupled to the output of each serially connected inverter and a secondary winding coupled to an output circuit, means for sampling the alternating current output of said first inverter, means for rectifying said sampled alternating current to a direct current and feeding said direct current to the input of said second inverter, thereby to substantially balance the input voltages from said source of direct current to said first and second inverters.

Claim 5

An inverter power supply comprising a source of direct current, first and second inverters, said inverters having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, capacitor means connected to the output of said first inverter, a pair of serially-connected diodes connected across the input of said second inverter, said capacitor means connected to feed its output to the common junction of said first and second diodes, thereby to substantially balance the input voltages from said direct current source to said first and second inverters.

Claim 6

An inverter power supply comprising a source of direct current, first and second inverters, said inverters having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, capacitor means connected to the output of said first inverter, a pair of serially-connected diodes connected across the input of said second inverter, said capacitor means connected to feed its output to the common junction of said first and second diodes, thereby to substantially balance the input voltages from said direct current source to said first and second inverters.

Claim 7

An inverter power supply comprising a direct current source, switching means, first and second sine wave inverters coupled in series with each other by way of said switching means to said source of direct current, a pair of series capacitors connected to form a parallel resonant circuit with each of said sine wave inverters and connected in series with each other to form an output circuit, means connected to the output of each series-connected inverter and adapted to provide an output which is the vector sum of said first and second sine wave inverters, a pair of serially connected diodes coupled respectively across the input of each of said first and second sine wave inverters, and coupling means cross-coupled from the common junction of each of the pairs of said series capacitors to the common junction, respectively, of each other pair of serially connected diodes to balance the input voltages from said direct current source to said first and second sine wave inverters irrespective of the direction of unbalance of the input voltage to either of said first and second sine wave inverters.

Claim 8

An inverter power supply comprising a direct current source, switching means, first and second sine wave inverters coupled in series with each other by way of said switching means to said source of direct current, a pair of series capacitors connected to form a parallel resonant circuit with each of said sine wave inverters and connected in series with each other to form an output circuit, means connected to the output of each series-connected inverter and adapted to provide an output which is the vector sum of said first and second sine wave inverters, a pair of serially connected diodes coupled respectively across the input of each of said first and second sine wave inverters, and coupling means cross-coupled from the common junction of each of the pairs of said series capacitors to the common junction, respectively, of each other pair of serially connected diodes to balance the input voltages from said direct current source to said first and second sine wave inverters irrespective of the direction of unbalance of the input voltage to either of said first and second sine wave inverters.

Claim 9

In combination; a source of direct current, first and second inverters, each inverter having a DC input and an AC output, the inputs of said first and second inverters connected in series with each other and said source of direct current, means for sampling the AC output of said first and second inverters, means for rectifying the AC output of each smaple, and means for feeding the rectified sampled output of said second inverter to the input of said first inverter and the rectified sampled output of said first inverter to the input of said second inverter, thereby to augment the DC input of either of said inverters to maintain the input voltages of said first and second inverters substantially in balance.

Claim 10

In combination; a source of direct current, first and second inverters, each inverter having a DC input and an AC output, the inputs of said first and second inverters connected in series with each other and said source of direct current, means for sampling the AC output of said first and second inverters, means for rectifying the AC output of each smaple, and means for feeding the rectified sampled output of said second inverter to the input of said first inverter and the rectified sampled output of said first inverter to the input of said second inverter, thereby to augment the DC input of either of said inverters to maintain the input voltages of said first and second inverters substantially in balance.

Claim 11

An inverter power supply comprising a source of direct current, first and second sine wave inverters coupled in series with each other and said source of direct current, each inverter having a DC input and an AC output, means for providing a sample output of the AC output of each of said inverters, means for rectifying each sample output to provide a direct current, means for applying the direct current from the output of the first of said sine wave inverters to the input of the second of said sine wave inverters and means for applying the direct current from the output of the second of said sine wave inverters to the input of the first of said sine wave inverters, an output circuit coupled to said first and second sine wave inverters and adpated to provide an output which is the vector sum of said first and second sine wave inverters, means for sampling said output, means for comparing sAid sampled output with a reference source to provide a difference control signal, and means in response to said control signal to alter the phase of one sine wave inverter with respect to the other to control the output of said inverters.

Claim 12

An inverter power supply comprising a source of direct current, first and second sine wave inverters coupled in series with each other and said source of direct current, each inverter having a DC input and an AC output, means for providing a sample output of the AC output of each of said inverters, means for rectifying each sample output to provide a direct current, means for applying the direct current from the output of the first of said sine wave inverters to the input of the second of said sine wave inverters and means for applying the direct current from the output of the second of said sine wave inverters to the input of the first of said sine wave inverters, an output circuit coupled to said first and second sine wave inverters and adpated to provide an output which is the vector sum of said first and second sine wave inverters, means for sampling said output, means for comparing sAid sampled output with a reference source to provide a difference control signal, and means in response to said control signal to alter the phase of one sine wave inverter with respect to the other to control the output of said inverters.

Claim 13

An inverter power supply comprising a source of direct current, switching means, first and second sine wave inverters having inductor windings coupled in series with each other by way of said switching means and said source of direct current, a capacitor connected to form a parallel resonant circuit with said inductor windings, means for coupling the output of said first and second sine wave inverters to an output circuit providing a resultant output voltage, means for rectifying said output voltage, means for comparing said rectified output voltage with a reference source to provide a control signal, means in response to said control signal to delay the triggering into conduction of said switching means of said inverter to maintain the amplitude of said resultant output voltage substantially constant, means for providing a sample of the output of one of said sine wave inverters, means for rectifying said sample to provide a direct current, and means for applying the rectified direct current to augment the input voltage of the other of said sine wave inverters to maintain in balance said soruce of direct current to said first and second sine wave inverters.

Claim 14

An inverter power supply comprising a source of direct current, switching means, first and second sine wave inverters having inductor windings coupled in series with each other by way of said switching means and said source of direct current, a capacitor connected to form a parallel resonant circuit with said inductor windings, means for coupling the output of said first and second sine wave inverters to an output circuit providing a resultant output voltage, means for rectifying said output voltage, means for comparing said rectified output voltage with a reference source to provide a control signal, means in response to said control signal to delay the triggering into conduction of said switching means of said inverter to maintain the amplitude of said resultant output voltage substantially constant, means for providing a sample of the output of one of said sine wave inverters, means for rectifying said sample to provide a direct current, and means for applying the rectified direct current to augment the input voltage of the other of said sine wave inverters to maintain in balance said soruce of direct current to said first and second sine wave inverters.

Claim 15

The inverter power supply as set forth in claim 7 in which the switching means comprises SCR''s.

Claim 16

The combination as set forth in claim 2 in which said switching means includes a diode connected in shunt with said switching means and poled in a direction to provide a voltage drop adapted to back bias said switching means on alternate half cycles of operation of said switching means.

Claim 17

The combination as set forth in claim 1 in which additional means is provided for obtaining another sample of the output of the other of said inverters, means for rectifying said other sample to another direct current output, and means for feeding said other rectified direct current output to the input of said first inverter to augment its DC input for maintaining substantially in balance the source of direct current to said first and second inverters.

Claim 18

An inverter power supply comprising, a source of direct current, first and second inverters, each inverter having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, means for coupling the output of said first and second inverters to an output circuit to provide a resultant output voltage, means for providing a sample of the AC output of one of said inverters, means for rectifying said sample to a direct current output, means for feeding said direct current output to the DC input of the other of said inverters, means for comparing the resultant output voltage with a reference voltage to provide a control signal, and means in response to said control signal to alter the phase of one of said inverters with respect to the phase of the other to vary the resultant output voltage.

Claim 19

An inverter power supply comprising, a source of direct current, first and second inverters, each inverter having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, means for coupling the output of said first and second inverters to an output circuit to provide a resultant output voltage, means for providing a sample of the AC output of one of said inverters, means for rectifying said sample to a direct current output, means for feeding said direct current output to the DC input of the other of said inverters, means for comparing the resultant output voltage with a reference voltage to provide a control signal, and means in response to said control signal to alter the phase of one of said inverters with respect to the phase of the other to vary the resultant output voltage.

Claim 20

The inverter power supply as set forth in claim 11 in which each of said inverters includes switching means connected in series with said source of direct current, and means for triggering said switching means of said first inverter into conduction at predetermined times with respect to the triggering into conduction of said second inverter.

Claim 21

In combination, a source of direct current, first and second inverters, said inverters having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, transformer coupling means connected to the output of said first inverter, a rectifier circuit having its output connected across the input of said second inverter, said transformer coupling means connected to feed its output to the input of said rectifier circuit, thereby to substantially balance the input voltages from saiD direct current source to said first and second inverters.

Claim 22

In combination, a source of direct current, first and second inverters, said inverters having a DC input and an AC output, said inverters connected in series with each other and said source of direct current, transformer coupling means connected to the output of said first inverter, a rectifier circuit having its output connected across the input of said second inverter, said transformer coupling means connected to feed its output to the input of said rectifier circuit, thereby to substantially balance the input voltages from saiD direct current source to said first and second inverters.