Electric power supply system

Claim 2

An electric power supply system according to claim 1, wherein said power converter control circuit regulates the output frequency of said power converter such that said first AC power is constantly maintained higher than said second AC power.

Claim 3

An electric power supply system according to claim 1, wherein said regulation input means includes an analogue switch having inputs connected to the output of said comparator means and the output of a power sensor for detecting said active component of said first AC power, respectively, and having an output connected to a voltage-controlled oscillator, wherein when it is decided by said comparator means that said first AC current exceeds said predetermined, said analogue switch is closed to thereby apply said active component outputted from said power sensor to said voltage-controlled oscillator whose output frequency is utilized for regulating the output frequency of said power converter so that it coincides with the output frequency of said second AC power source.

Claim 4

An electric power supply system according to claim 1, wherein said regulation input means allows the active component of said first AC power to pass therethrough in a transient parallel operation for supplying said first and second AC powers to said load through said switch means, while inhibiting the active component of said first AC power from passing therethrough in an isolated operation for supplying only said first AC power to said load; and wherein said power converter control means regulates the output frequency of said power converter in said transient parallel operation by regulating the output frequency of said power converter to a center frequency corresponding to a no-load state in said isolated operation in succession to termination of said transient parallel operation.

Claim 5

An electric power supply system according to claim 4, wherein said regulation input means includes a variable gain amplifier having a gain variable in dependence on the output of said comparator means.

Claim 6

An electric power supply system according to Claim 4, wherein said power converter control circuit regulates the output frequency of said power converter such that said first AC power is constantly maintained higher than said second AC power.

Claim 7

A power supply system, comprising: a power converter for outputting a first AC power of a first AC voltage and a first AC current; an AC power source for outputting a second AC power of a second AC voltage and a second AC current; switch means for supplying at least one of said first and second AC powers to a load; and a power converter control circuit for regulating an output frequency of said power converter in accordance with an active component of said first AC power; wherein said power converter control circuit includes: power sensor means for detecting said first AC power; comparator means for making decision on the basis of output of said power sensor means as to whether or not said first AC power is in a regenerative state; and regulation input means for fetching an active component of said first AC power in response to an output signal of said comparator means; wherein an output frequency of said power converter is so regulated as to coincide with an output frequency of said AC power source in dependence on said active component of said first AC power, when said first AC power is in the regenerative state.

Claim 8

An electric power supply system according to Claim 7, wherein said regulation input means includes an analogue switch having an input connected to the output of said power sensor, a one-shot multivibrator connected between said comparator means and said analogue switch, and a voltage-controlled oscillator connected to an output of said analogue switch, and wherein when the output signal of said comparator means indicates that said power converter is in the regenerative state, said one-shot multivibrator outputs a signal of a duration selected longer than that of the parallel operation to said analogue switch which responds thereto by supplying the output of said power sensor to said voltage-controlled oscillator whose output frequency is utilized for controlling said power converter.

Claim 9

An electric power supply system according to Claim 7, wherein said power converter control circuit regulates the output frequency of said power converter such that said first AC power is constantly maintained higher than said second AC power.

Claim 10

An electric power supply system, comprising: a power converter for outputting a first AC power of a first AC voltage and a first AC current; an AC power source for outputting a second AC power of a second AC voltage and a second AC current; switch means for supplying at least one of said first and second AC powers to a load; and a power converter control circuit for regulating an output frequency of said power converter; wherein said power converter control circuit includes: current sensor means for detecting said first AC current; comparator means for making decision as to whether or not said first AC current exceeds a predetermined value; and frequency change-over means for changing the output frequency of said power converter in response to an output signal of said comparator means and in dependence on polarity of said active component of said first AC power; wherein the output frequency of said power converter is so regulated as to be maximum when said first AC current exceeds said predetermined value and when said active component is of negative polarity; while said output frequency of said power converter is so regulated as to be minimum when said first AC current exceeds said predetermined value and when said active component is of positive polarity; and said output frequency of said power converter is so regulated as to become a center frequency when said first AC current is below said predetermined value.

Claim 11

An electric power supply system, comprising: a power converter for outputting a first AC power of a first AC voltage and a first AC current; an AC power source for outputting a second AC power of a second AC voltage and a second AC current; switch means for supplying at least one of said first and second powers to a load; and a power converter control circuit for regulating an output frequency of said power converter; said power converter being constituted by an inverter; said power converter control circuit including a DC current sensor for detecting a DC current value of said inverter; wherein the output frequency of said power converter is so regulated as to coincide with the output frequency of said AC power source in dependence on said DC current value.