Method and apparatus for electronic power control

• US 7,595,613 B2
• Filed: 12/28/2007
• Issued: 09/29/2009
• Est. Priority Date: 01/11/1995
• Status: Expired due to Fees

• Current Assignee: MicroPlanet Incorporated (MicroPlanet Technology Corporation)
• Original Assignee: MicroPlanet Incorporated (MicroPlanet Technology Corporation)
• Inventors: Thompson, John, Baretich, David F., Wiegand, Gregory P.
• Primary Examiner(s): Patel; Rajnikant B
• Application Number:
  US11/965,942
• Publication Number:
  US 20080197819A1
• Time in Patent Office: 641 Days
• Field of Search: 323222-225, 323282-288, 323/243, 323/207, 323/335, 323/351, 363 16- 17, 363/65, 363/71, 363/89, 363/98
• US Class Current: 323/223
• CPC Class Codes: G05F 1/613 using semiconductor devices in parallel with the load as final control devices G05F1/461 takes precedence
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33569 having several active switching elements H02M3/3353 takes precedence
• CPC Class Codes: H02M 5/293 using semiconductor devices only
• 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

The method of the invention in one aspect involves electronic power control by varying the amplitude of an electrical power supply voltage, independent of frequency, whereby the output frequency will always be the same as the input frequency. An electrical circuit apparatus for accomplishing this function in a specific embodiment is also disclosed herein. The specific circuitry of this aspect of the invention uses eight solid state switches, such as IGBT'"'"'s, eight diodes, an inductor, input and output filters and novel controlling circuitry. The controller apparatus and methods of the invention may be used to implement all otherwise conventional converter types, buck, boost, and inverting (and duals of these) versions to obtain different regulating characteristics, including galvanic isolation of the output from the input. Indeed, the eight-switch controller can act to either buck or boost the input voltage, and can switch between bucking and boosting during a cycle, thus providing more control of the regulated output voltage. The inventive methods and devices may be used in power factor correction, voltage and/or current harmonic filtering and neutralization, line and load conditioning, control of power transfer between two power grids, and programmable control of surges, sags, dropouts and most other voltage regulation problems.

Claims

1. An AC to AC power controller having an output for connection to a load, the controller comprising:

a power regulator circuit comprising;

first, second, third and fourth independently controllable switches, wherein the first switch is connected to the second switch, the second switch is connected to the third switch, and the third switch is connected to the fourth switch; and

an inductor connected to at least one of the switches;

a polarity detector in parallel with an input voltage to the power regulator;

a duty cycle modulator; and

a logic control circuit comprising a first output connected to the first switch, a second output connected to the second switch, a third output connected to the third switch and a fourth output connected to the fourth switch, wherein the logic control circuit is connected to receive as input at least one output of the polarity detector and at least one output of the duty cycle modulator, and wherein the logic control circuit is configured to control the first, second, third and fourth switches such that there is always an electrically conducting path through the switches and such that at least one switch is conducting.

2. The controller of claim 1, wherein the power regulator circuit comprises a power regulator topology selected from the group consisting of a buck topology, a boost topology, an inverting topology, a flyback topology, a dual of a buck topology, a dual of a boost topology, a dual of an inverting topology, and a dual of a flyback topology.

3. The controller of claim 1, wherein the controller is a single stage controller.

4. The controller of claim 1, wherein the controller further comprises a second power regulator circuit comprising four independently controllable switches and an inductor, wherein the power regulator circuit is connected to a first input line and the second power regulator circuit is connected to a second input line.

5. The controller of claim 1, wherein the logic control circuit further comprises:

a first logic gate connected to receive as input;

an inverted output of the polarity detector via a first turn-off delay circuit; and

a non-inverted output of the duty cycle modulator via a first turn-on delay circuit; and

a second logic gate connected to receive as input;

a non-inverted output of the polarity detector via a second turn-off delay circuit; and

the non-inverted output of the duty cycle modulator via the turn-on delay circuit;

a third logic gate connected to receive as input;

the inverted output of the polarity detector via the first turn-off delay circuit; and

an inverted output of the duty cycle modulator via a second turn-on delay circuit; and

a fourth logic gate connected to receive as input;

the non-inverted output of the polarity detector via the second turn-off delay circuit; and

the inverted output of the duty cycle modulator via the second turn-on delay circuit.

6. The controller of claim 5, wherein the first, second, third and fourth logic gates are OR gates.

7. The controller of claim 5, wherein an output of the first logic gate is electrically connected to the first switch;

an output of the second logic gate is electrically connected to the second switch;

an output of the third logic gate is electrically connected to the third switch; and

an output of the fourth logic gate is electrically connected to the fourth switch.

8. The controller of claim 1, wherein at least one of the independently controllable switches comprises a solid state device, wherein the power regulator further comprises a diode connected in parallel across a source and a drain of the solid state device, and wherein an anode of the diode is connected to the source of the solid state device and a cathode of the diode is connected to the drain of the solid state device.

9. The controller of claim 1, wherein the switches comprise at least one device selected from the group consisting of a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET), a magnetic contact transistor (MCT), and a gate turn-off thyristor (GTO).

10. The controller of claim 1, wherein two of the four independently controllable switches are connected between the input voltage and the inductor, and wherein two of the four independently controllable switches are connected between the inductor and a return.

11. A method of controlling an electrical voltage produced by an AC to AC converter, the method comprising varying an amplitude of an input voltage waveform independent of its frequency to produce a selected output voltage to a load, wherein the varying comprises:

switching an input through an inductor by variable duty cycle modulation of a power regulator; and

modulating the switching during operation such that there is always an electrically conducting path through at least one switch.

12. A variable power factor corrector comprising:

a power factor capacitor connected in parallel with a load on an AC line;

a power controller for regulating an AC to AC input voltage conversion, the power controller connected in series with the power factor capacitor, wherein the power controller comprises;

a power regulator circuit comprising a pair of switches and an inductor, wherein each of the pair of switches is bi-directional and implemented as a pair of unidirectional switches;

a polarity detector in parallel with an input voltage to the power regulator;

a duty cycle modulator; and

a logic control circuit comprising a first output connected to a first unidirectional switch, a second output connected to a second unidirectional switch, a third output connected to a third unidirectional switch and a fourth output connected to a fourth unidirectional switch, wherein the logic control circuit is connected to receive as input at least one output of the polarity detector and at least one output of the duty cycle modulator, and wherein the logic control circuit is configured to control the unidirectional switches such that there is always an electrically conducting path through the switches and such that at least one switch is conducting; and

wherein the power controller generates a line-driven variable voltage output that varies an amount of capacitance reflected back onto the AC line.

13. The power factor corrector of claim 12, further comprising:

a current sensor in series with a load on the AC line;

a phase delay detector connected to receive voltage input from the AC line and current sense input from the current sensor;

a power factor error amplifier fed by an output of the phase delay detector, the amplifier feeding a signal to the power controller logic control circuit; and

whereby a selected power factor correction may be automatically maintained.

14. The power factor corrector of claim 13, further comprising:

a second current sensor connected in series between the power controller and the power factor capacitor; and

a harmonic error amplifier fed by an output of the current sensor, the amplifier feeding a signal to the power controller logic control circuit for auto resonance suppression and harmonic dampening.

15. The power factor corrector of claim 12, wherein the AC line is part of a three phase AC system:

wherein the power controller is connected in parallel between the AC line and a third AC line;

wherein the power factor capacitor is connected between an output of the power controller and the third AC line;

wherein a second power controller is connected in parallel between a second AC line and the third AC line;

wherein a second capacitor is connected between an output of the second power controller and the third AC line; and

wherein a third capacitor is connected between an output of the first power controller and the output of the second power controller.

16. An AC to AC power controller for controlling an AC input voltage to a load, the controller comprising:

a power regulator circuit comprising eight independently controllable switches; and

a polarity detector in parallel with an input voltage of the power regulator;

a duty cycle modulator; and

a logic control circuit comprising wherein each of the eight switches is controlled by an output of the logic control circuit, wherein the logic control circuit is connected to receive as input at least one output of the polarity detector and at least one output of the duty cycle modulator, and wherein the logic control circuit is configured to control the switches such that there is always an electrically conducting path through the switches and such that at least one switch is conducting.

17. The controller of claim 16, wherein the power regulator circuit comprises a power regulator topology selected from the group consisting of a buck topology, a boost topology, an inverting topology, a flyback topology, a dual of a buck topology, a dual of a boost topology, a dual of an inverting topology, and a dual of a flyback topology.

18. The controller of claim 16, wherein the controller is a single stage controller.

19. The controller of claim 16, wherein the controller further comprises a second power regulator circuit comprising eight independently controllable switches.

20. The controller of claim 19, wherein the power regulator circuit corresponds to a first input line and the second power regulator circuit corresponds to a second input line.

21. The controller of claim 16, wherein the logic control circuit further comprises eight logic gates, wherein the logical control circuit is connected such that:

the first, third, fifth and seventh logic gates each receive as a first input an inverted output from the polarity detector via a turn-off delay;

the second, fourth, sixth and eighth logic gates each receive as a first input a non-inverted output from the polarity detector via a turn-off delay;

the first, second, fifth, and sixth logic gates receive as a second input an inverted output from the duty cycle monitor via a turn-on delay; and

the third, fourth, seventh, and eighth logic gates receive as a second input a non-inverted output from the duty cycle modulator via a turn-on delay, and wherein an output of each logic gate drives one of the switches.

22. The controller of claim 21, wherein the first, second, third, fourth, fifth, sixth, seventh and eighth logic gates are OR gates.

23. The controller of claim 16, wherein a first pair of the switches is connected between an input and a first inductor, wherein a second pair of the switches is connected between the first inductor and a return, wherein a third pair of the switches is connected between the input and a second inductor, and wherein a fourth pair of the switches is connected between the second inductor and the return.