Power factor corrected single-phase AC-DC power converter using natural modulation
First Claim
1. A single-phase power factor correcting ac-dc converter having an input for receiving a full-wave rectified ac input voltage and an input current, an output for putting out a dc output voltage, and a common return, comprisinga main power path in a series connection from the input to the output comprisingan input inductor,a boost switch,a first buck switch, andan output inductor, anda storage energy path in a series connection from a connection of the input inductor with the boost switch to a connection of the first buck switch with the output inductor comprisinga boost rectifier, anda second buck switch,there also beinga buffer capacitor connected from a connection of the boost switch with the first buck switch to the common return,a storage capacitor for storing energy connected from a connection of the boost rectifier with the second buck switch to the common return,a catch rectifier switch connected from the connection of the first buck switch with the output inductor to the common return, andan output filter capacitor connected from the output to the common return,the single-phase power factor correcting ac-dc converter further having at leasta first mode of operation for when the full wave rectified ac voltage is below its rms voltage, anda second mode of operation for when the full wave rectified ac voltage is above its rms voltage,the first mode of operation comprising:
- the boost switch is on,the boost rectifier is reverse-biased,the first buck switch controls by pulse width modulation the input current for power factor correction,the second buck switch controls by pulse width modulation the output dc voltage, andthe catch rectifier conducts a current of the output inductor when the first and second buck switches are off, andthe second mode of operation comprising;
the first buck switch is on,the second buck switch is offthe boost switch controls by pulse width modulation the output dc voltage, andthe boost rectifier is forward biased when the boost switch is off.
0 Assignments
0 Petitions
Accused Products
Abstract
A power factor corrected (pfc) ac-dc converter has a modified boost input and a modified buck output. Unlike the prior art boost input, the boost switch returns to the output, not to ground. Unlike the prior art buck output stage, a third switch connects to the input. This allows much of the input current to pass through the converter to the output. There is no input current measurement, but nearly ideal power factor correction is achieved through “natural modulation.” A preferred pfc ac-dc converter uses a variable dc-dc transformer on its output, as a post regulator, to provide dielectric isolation and to provide voltage level shifting. The output of the pfc ac-dc converter has the control characteristics of a buck converter, so it is a natural mate for the variable dc-dc transformer. An ac-dc buck converter is most efficient at its maximum duty cycle. It cannot regulate for a lower input voltage, but it can reduce its duty-cycle to control for higher input voltages. A variable dc-dc transformer is most efficient at its maximum ratio. It cannot regulate for a higher input voltage, but it can reduce its effective turns ratio to control for a lower input voltage. With a small overlap in their control ranges, both parts of the power system can operate at maximum efficiency. The variable dc-dc transformer controls the output voltage for nominal and low input voltage. The ac-dc buck converter limits over-voltage transients.
-
Citations
22 Claims
-
1. A single-phase power factor correcting ac-dc converter having an input for receiving a full-wave rectified ac input voltage and an input current, an output for putting out a dc output voltage, and a common return, comprising
a main power path in a series connection from the input to the output comprising an input inductor, a boost switch, a first buck switch, and an output inductor, and a storage energy path in a series connection from a connection of the input inductor with the boost switch to a connection of the first buck switch with the output inductor comprising a boost rectifier, and a second buck switch, there also being a buffer capacitor connected from a connection of the boost switch with the first buck switch to the common return, a storage capacitor for storing energy connected from a connection of the boost rectifier with the second buck switch to the common return, a catch rectifier switch connected from the connection of the first buck switch with the output inductor to the common return, and an output filter capacitor connected from the output to the common return, the single-phase power factor correcting ac-dc converter further having at least a first mode of operation for when the full wave rectified ac voltage is below its rms voltage, and a second mode of operation for when the full wave rectified ac voltage is above its rms voltage, the first mode of operation comprising: -
the boost switch is on, the boost rectifier is reverse-biased, the first buck switch controls by pulse width modulation the input current for power factor correction, the second buck switch controls by pulse width modulation the output dc voltage, and the catch rectifier conducts a current of the output inductor when the first and second buck switches are off, and the second mode of operation comprising; the first buck switch is on, the second buck switch is off the boost switch controls by pulse width modulation the output dc voltage, and the boost rectifier is forward biased when the boost switch is off. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 17, 18)
-
-
11. A single-phase power factor correcting ac-dc converter having a first input and a second input for receiving an ac input voltage and an input current, an output for putting out a dc output voltage, and a common output return, comprising
a first main power path in a series connection from the first input to the output comprising at least a first input inductor, a first boost switch, a first buck switch, and an output inductor, and a first storage energy path in a series connection from a connection of the input inductor with the first boost switch to a connection of the first buck switch with the output inductor comprising a first boost rectifier, and a second buck switch, a second main power path in a series connection from the second input to a connection of the first boost switch with the first buck switch comprising a second boost switch a second storage energy path in a series connection from the second input to a connection of the first boost rectifier with the second buck switch compising a second boost rectifier a first ac return path in a series connection from the first input to the common output return comprising a first return rectifier, and a second ac return path in a series connection from the second input to the common output return comprising a second return rectifier, there also being a buffer capacitor connected from a connection of the first boost switch with the first buck switch to the common output return, a storage capacitor for storing energy connected from a connection of the first boost rectifier with the second buck switch to the common output return, a catch rectifier switch connected from the connection of the first buck switch with the output inductor to the common output return, and an output filter capacitor connected from the output to the common output return, when the ac input voltage is positive when referenced from the first input to the second input the second return rectifier is forward-biased and the first return rectifier is reverse-biased, when the ac input voltage is negative when referenced from the first input to the second input the first return rectifier is forward-biased and the second return rectifier is reverse-biased, the single-phase power factor correcting ac-dc converter further having at least a first mode of operation for when the magnitude of the ac input voltage is below its rms voltage, and a second mode of operation for when the magnitude of the ac input voltage is above its rms voltage, the first mode of operation comprising: -
when the ac input voltage is positive when referenced from the first input to the second input the first boost switch is on, and the second boost switch is off, when the ac input voltage is negative when referenced from the first input to the second input the second boost switch is on and the first boost switch is off, the first and second boost rectifiers are reverse-biased, the first buck switch controls by pulse width modulation the input current for power factor correction, the second buck switch controls by pulse width modulation the output dc voltage, and the catch rectifier conducts a current of the output inductor when the first and second buck switches are off, and the second mode of operation comprising; the first buck switch is on and the second buck switch is off when the ac input voltage is positive when referenced from the first input to the second input the first boost switch controls by pulse width modulation the output voltage, and the second boost switch is off the first boost rectifier is forward-biased when the first boost switch is off, and the second boost rectifier is reversed-biased when the ac input voltage is negative when referenced from the first input to the second input the second boost switch controls by pulse width modulation the output voltage, and the first boost switch is off the second boost rectifier is forward-biased when the second boost switch is off, and the first boost rectifier is reversed-biased. - View Dependent Claims (12, 13, 14, 15, 16, 19, 20, 21, 22)
-
Specification
-
- Resources
-
Current AssigneeEdward Herbert
-
Original AssigneeEdward Herbert
-
InventorsHerbert, Edward
-
Primary Examiner(s)Ullah; Akm E
-
Assistant Examiner(s)Zhang; Jue
-
Application NumberUS11/767,704Time in Patent Office757 DaysField of Search363/34, 363/44, 363/124, 363/125, 363/127, 363/89, 323/222US Class Current363/124CPC Class CodesG05F 1/70 Regulating power factor; Re...H02M 1/4208 Arrangements for improving ...H02M 1/4258 using a single converter st...Y02B 70/10 Technologies improving the ...Y02P 80/10 Efficient use of energy, e....
