Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
200 words
A power supply apparatus comprising: single-phase full-wave rectifier means coupled to a power source having a low frequency, for rectifying a first AC (alternating current) voltage to produce a DC (direct current) voltage; DC-to-AC inverter means including a first pair of switching elements connected to an input terminal thereof, and a second pair of switching elements connected to an output terminal thereof and to the first pair of switching elements to constitute a bridge inverter circuit, for inverting the DC voltage into a second AC voltage to be applied to a load; and, switching control means connected to the DC/AC inverter means for alternately turning ON/OFF the second pair of switching elements in response to a sync signal (SYC) in synchronism with the first AC voltage at the low frequency of the power source, and for alternately turning ON/OFF the first pair of switching elements in response to a PWM (pulse-width modulation) control signal obtained from the first AC voltage and the second AC voltage, in a PWM control mode at a modulation frequency higher than the low frequency of the power source, whereby a phase of the second AC voltage is opposite to that of the first AC voltage.
Claim 2
Dependent Claim
200 words
A power supply apparatus comprising: single-phase full-wave rectifier means coupled to a power source having a low frequency, for rectifying a first AC (alternating current) voltage to produce a DC (direct current) voltage; DC-to-AC inverter means including a first pair of switching elements connected to an input terminal thereof, and a second pair of switching elements connected to an output terminal thereof and to the first pair of switching elements to constitute a bridge inverter circuit, for inverting the DC voltage into a second AC voltage to be applied to a load; and, switching control means connected to the DC/AC inverter means for alternately turning ON/OFF the second pair of switching elements in response to a sync signal (SYC) in synchronism with the first AC voltage at the low frequency of the power source, and for alternately turning ON/OFF the first pair of switching elements in response to a PWM (pulse-width modulation) control signal obtained from the first AC voltage and the second AC voltage, in a PWM control mode at a modulation frequency higher than the low frequency of the power source, whereby a phase of the second AC voltage is opposite to that of the first AC voltage.
Claim 3
Dependent Claim
35 words
A power supply apparatus as claimed in claim 1, further comprising a smoothing capacitor interposed between the rectifier means and DC/AC inverter means, for smoothing the DC voltage E o derived from the rectifier means.
Claim 4
Dependent Claim
29 words
A power supply apparatus as claimed in claim 1, further comprising an L type filter constructed of an inductor and a capacitor, interposed between the DC/AC inverter and load.
Claim 5
Dependent Claim
81 words
A power supply apparatus as claimed in claim 1, wherein said switching control means includes: a zerocross detector for receiving the first AC voltage of the power source to detect zerocross points thereof, thereby producing said sync signal in synchronism with the zerocross points; a PLL (phase-locked loop) circuit for receiving the first AC voltage to derive a reference voltage; and, a PWM control signal generator for generating said PWM control signal from said reference voltage and said second AC voltage.
Claim 6
Dependent Claim
24 words
A power supply apparatus as claimed in claim 4, wherein said PWM control signal generator includes an adder an error amplifier and a comparator.