PWM power supply eliminating modulation-frequency components from ground potentials
First Claim
1. A power supply apparatus comprising:
- chopper means, coupled to an AC (alternating current) power source capable of supplying a first AC voltage having a low frequency from a pair of output terminals, for chopping said first AC voltage by switching first and second chopper switching elements to obtain a positive DC (direct current) voltage from a positive half cycle of said first AC voltage appearing at one output terminal of said output terminals and a negative DC voltage from a negative half cycle of said first AC voltage appearing at said one output terminal with a common voltage appearing at another output terminal of said output terminals which is a common voltage output terminal; and
DC-to-AC inverter means including a pair of third and fourth inverter switching elements and a chopper/PWM (pulse width modulation) controller for controlling chopper operations of said first and second chopper switching elements so as to obtain corresponding voltages to said positive and negative DC voltages and also for controlling switching operations of said third and fourth inverter switching elements in a PWM control mode so as to invert said positive and negative DC voltages into a second AC voltage having a modulation frequency higher than said low frequency with respect to said common voltage output terminal, whereby said second AC voltage contains no modulation frequency component.
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Accused Products
Abstract
In a PWM control type power supply apparatus, a modulation (high frequency) signal component is eliminated from an AC output. The PWM control type power supply apparatus includes: AC-to-DC converting means coupled to an AC (alternating current) power source capable of supplying a first AC voltage having a low frequency from a pair of output terminals, for converting the first AC voltage to obtain a positive DC (direct current) voltage from a positive half cycle of the first AC voltage appearing at one output terminal and a negative DC voltage from a negative half cycle of the first AC voltage appearing at one output terminal with a common voltage appearing at the other output terminal; and, DC-to-AC inverter means including a pair of first and second switching elements, and a PWM (pulse width modulation) controller for controlling switching operations of the first and second switching elements in a PWM control mode so as to invert the positive and negative DC voltage into a second AC voltage having a modulation frequency higher than the low frequency with respect to the common voltage output terminal, whereby the second AC voltage contains no modulation frequency component.
77 Citations
14 Claims
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1. A power supply apparatus comprising:
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chopper means, coupled to an AC (alternating current) power source capable of supplying a first AC voltage having a low frequency from a pair of output terminals, for chopping said first AC voltage by switching first and second chopper switching elements to obtain a positive DC (direct current) voltage from a positive half cycle of said first AC voltage appearing at one output terminal of said output terminals and a negative DC voltage from a negative half cycle of said first AC voltage appearing at said one output terminal with a common voltage appearing at another output terminal of said output terminals which is a common voltage output terminal; and DC-to-AC inverter means including a pair of third and fourth inverter switching elements and a chopper/PWM (pulse width modulation) controller for controlling chopper operations of said first and second chopper switching elements so as to obtain corresponding voltages to said positive and negative DC voltages and also for controlling switching operations of said third and fourth inverter switching elements in a PWM control mode so as to invert said positive and negative DC voltages into a second AC voltage having a modulation frequency higher than said low frequency with respect to said common voltage output terminal, whereby said second AC voltage contains no modulation frequency component. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A power supply apparatus comprising:
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chopper means, coupled to an AC (alternating current) power source capable of supplying a first AC voltage having a low frequency from a pair of output terminals, for chopping said first AC voltage by switching first and second chopper switching elements coupled across first and second diodes to obtain a positive DC (direct current) voltage from a positive half cycle of said first AC voltage appearing at one output terminal of said output terminals and a negative DC voltage from a negative half cycle of said first AC voltage appearing at said one output terminal with a common voltage appearing at another output terminal of said output terminals which is a common voltage output terminal; and DC-to-AC inverter means including a pair of third and fourth inverter switching elements, and a chopper/PWM (pulse width modulation) controller responsive to said first AC voltages for controlling chopper operations of said first and second chopper switching elements so as to obtain corresponding voltages to said positive and negative DC voltages and also for controlling switching operations of said third and fourth inverter switching elements in a PWM control mode so as to invert said positive and negative DC voltages into a second AC voltage having a modulation frequency higher than said low frequency with respect to said common voltage output terminal, whereby said second AC voltage contains no modulation frequency component. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification