Current harmonic, current form factor and power factor modification unit for rectifier supplied loads

• US 5,430,364 A
• Filed: 04/07/1994
• Issued: 07/04/1995
• Est. Priority Date: 01/23/1991
• Status: Expired due to Fees

• Current Assignee: John A. Gibson
• Original Assignee: John A. Gibson
• Inventors: Gibson, John A.
• Primary Examiner(s): Dougherty, Thomas M.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US08/224,999
• Time in Patent Office: 453 Days
• Field of Search: 363/37, 363/44, 363/81, 363/89, 363/79, 363/80, 363/95, 363/97, 363/124, 363/126, 323/207, 323/222, 323/282, 323/285, 323/299
• US Class Current: 323/207
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A device for connecting in series between a source of alternating current power and a direct current load which decouples the power flow from the source to the load and thereby enables efficient modification of the current waveform supplied by the source to reduce current harmonics, improve the current form factor and improve the power factor. Particular uses for the device include battery chargers, off-line switching power supplies as used by computers, electronic ballasts for fluorescent tubes and variable speed electric motor controls.

Claims

1. A device is provided for being connected in series between a source of electric power and a direct current load (for example, the input filter capacitor of an electronic ballast for a fluorescent lamp), comprising;

(I) a series electrical power circuit comprising;

(a) an electrical connector, such as one side of a male plug, for making the direct connection of one side of an electrical power supply to

(b) one of the A.C. input nodes of an electrical power rectifier module connected with the electrical connector means, such as four power diodes connected as a full wave bridge having first and second A.C. input nodes and a D.C. positive node and a D.C. negative node, with the D.C. positive node of the electrical power rectifier connected to

(c) one side of a current energy storage module connected with a direct current terminal of the electric power rectifier module, such as an inductor, whose other side is connected to the current input terminal of a current switch module for controlling the source current and connected with the current energy storage network such terminal being both

(d)(1) the current input side of a current switch, such as the drain terminal of a field effect power transistor, the current output side of said current switch, which is also the storage current output terminal of said current switch module, such as the source terminal of said field effect power transistor, which is connected to the first side of a current transducer module for providing an instantaneous measure of current which is the rectified source line current and

(d)(2) one side of a unidirectional switch, such as the anode side of a power diode, the second side of said unidirectional switch, such as the cathode side of said power diode, which is the load current output terminal of the current switch module, is connected to

(e) the positive node of a load, such as the input filter capacitor of an electronic fluorescent ballast, the negative node of which is in turn also connected to the first side of said current transducer module

(f)(1) making both the second side of said current switch and said negative node of the load connected to the first side of said current transducer module, such as one side of a very low value resistor, the second side of which is connected to the D.C. negative node of said electrical power rectifier

(f)(2) continuing via said electrical power rectifier to the other A.C. input node which is connected to

(g) an electrical power connector, such as the other side of said male plug, for finally making connection to the other side of the electrical power supply and

(II) a switch control module consisting of;

(a) a first sensing circuit network, connected to said current transducer module, for providing a first electrical signal, such as a voltage, that is a measure of AC current flowing from the electrical power source, said sensing circuit network provides differing electrical signals (voltages) corresponding to when said current switch is off, on, and the instantaneous level of AC current flow from the source, and

(b) a second sensing circuit network, connected to said D.C. positive node of said electrical power rectifier, for providing a second electrical signal, such as a voltage, that is a positive instantaneous measure of the voltage of the electrical power source, and

(c) an electrical switch control network which takes only said first and second current and voltage electrical signals and converts them, as is appropriate, into a digital "1'"'"'" or "0'"'"'" which is connected to the control terminal of said current switch, such as the gate terminal of said field effect power transistor thereby turning on or off said current switch.

2. Apparatus for connecting in series between a source of alternating current electrical power and a direct current load for decoupling the flow of power from the source to the load with said decoupling being arranged to maintain desired parameters of power flow such as current form factor, current harmonics, and power factor, to the combined device and load such apparatus being in combination;

(I) a series electrical power circuit comprising;

(a) an electrical connector, such as one side of a male plug, for making direct connection of one side of an electrical power supply to

(b) one of the A.C. input nodes of an electrical power rectifier module connected with the electrical connector means, such as four power diodes connected as a full wave bridge having first and second A.C. input nodes and a D.C. positive node and a D.C. negative node, with the D.C. positive node of the electrical power rectifier connected to

(c) one side of a current energy storage module connected with a direct current terminal of the electric power rectifier module, such as an inductor, whose other side is connected to both

(d)(1) the current input side of a current switch for controlling the source current and connected with the current energy storage network, such as the drain terminal of a field effect power transistor, the current output side of said current switch, such as the source side of said field effect power transistor, which is connected to the first side of a current transducer module for providing an instantaneous measure of current which is the rectified source line current and

(d)(2) one side of a unidirectional switch, such as the anode side of a power diode, the second side of said unidirectional switch, such as the cathode side of said power diode, is connected to

(e) the positive node of a load, such as the input filter capacitor of an electronic fluorescent ballast, the negative node of which is in turn also connected to the first side of said current transducer module

(f)(1) making both the second side of the current switch and the negative node of the load connected to the first side of said current transducer module, such as one side of a very low value resistor, the second side of which is connected to the D.C. negative node of the said electrical power rectifier

(f)(2) continuing via said electrical power rectifier to the other A.C. input node which is connected to

(g) an electrical power connector, such as the other side of said male plug, for finally making connection to the other side of the electrical power supply and

(II) an electronic sensing and switch control module consisting of;

(a) a first sensing circuit network, connected to said current transducer module, for providing a first electrical signal, such as a voltage, that is a measure of AC current flowing from the electrical power source, said sensing circuit network provides differing electrical signals (voltages) corresponding to when said current switch is off, on, and the instantaneous level of AC current flow in the supply, and

(b) a second sensing circuit network, connected to said D.C. positive node of said electrical power rectifier, for providing a second electrical signal, such as a voltage, that is a measure of the positive instantaneous voltage of the electrical power source, and

(d) an electrical signal processing network which takes only said first, and second, current and voltage electrical signals and converts them, as is appropriate, into a digital "1'"'"'" or "0'"'"'" which is connected to the control terminal of said current switch, such as the gate terminal of said field effect power transistor thereby turning on or off said current switch.

3. The combination defined in claim 2, wherein the current switch is a bipolar power transistor.

4. The combination defined in claim 2, wherein the current switch is an isolated base bipolar power transistor.

5. An apparatus for connecting in series between a source of alternating current electrical power and the input filter capacitor of an electronic ballast for a fluorescent lamp for decoupling the flow of power from the source to the load with said decoupling being arranged to maintain desired parameters of power flow such as current form factor, current harmonics, and power factor, to the combined device and electronic ballast such apparatus being in combination;

(I) a series electrical power circuit comprising;

(a) an electrical connector, such as one side of a male plug, for making direct connection of one side of an electrical power supply to

(b) one of the A.C. input nodes of an electrical power rectifier connected with the electrical connector means, such as four power diodes connected as a full wave bridge having first and second A.C. input nodes and a D.C. positive node and a D.C. negative node, with the D.C. positive node of the electrical power rectifier connected to

(c) one side of an inductor, whose other side is connected to the current input node of a current switch module for controlling the source current and connected with the current energy storage network, such node being connected to both

(d)(1) an input terminal of a current switch, such as the drain terminal of a field effect power transistor, whose output terminal, such as said transistor'"'"'s source terminal, is connected to the first side of a current measuring low value resistor

(d)(2) the anode side of a power diode, the cathode side of which is connected to

(e) the positive node of the input filter capacitor of an electronic fluorescent ballast, the negative node of which is in turn also connected to the first side of said current measuring low voltage value resistor

(f)(1) making both the switch output terminal and the negative node of the load connected to the first side of the low value resistor, the second side of which is connected to the D.C. negative node of said electrical power rectifier

(f)(2) continuing via said electrical power rectifier to the other A.C. input node which is connected to

(g) an electrical power connector, such as the other side of said male plug, for finally making connection to the other side of the electrical power supply and

(II) a switch control module consisting of;

(a) a first sensing circuit network, connected to said current measuring resistor, for providing a first electrical signal, such as a voltage, that is a measure of AC current flowing from the electrical power source, said sensing circuit network provides differing electrical signals (voltages) corresponding to when said current switch is off, on, and the instantaneous level of AC current flow from the source, and

(b) a second sensing circuit network, connected to said D.C. positive node of said electrical power rectifier, for providing a second electrical signal, such as a voltage, that is a positive instantaneous measure of the voltage of the electrical power source, a sensing circuit network in one embodiment being constructed using an operational amplifier integrated circuit and associated resistors, and

(d) an electrical signal processing network which takes only said first, and second, current and voltage electrical signals and converts them, as is appropriate, into a digital "1'"'"'" or "0'"'"'" which is connected to the control terminal of said current switch, such as the gate terminal of said field effect power transistor thereby turning on or off said current switch.

6. The combination defined in claim 5, wherein the current switch is a bipolar power transistor.

7. The combination defined in claim 5, wherein the current switch is an isolated base bipolar power transistor.