System and method for providing constant loading in AC power applications

• US 8,120,307 B2
• Filed: 08/06/2008
• Issued: 02/21/2012
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: Powerwise Group, Inc.
• Original Assignee: Powerwise Group, Inc.
• Inventors: Lumsden, John L.
• Primary Examiner(s): Benson, Walter
• Assistant Examiner(s): Chan, Kawing
• Application Number:
  US12/187,186
• Publication Number:
  US 20090200981A1
• Time in Patent Office: 1,294 Days
• Field of Search: 318/34, 318/727, 318/767, 318/812, 318/400.17, 318/599
• US Class Current: 318/812
• CPC Class Codes: H02P 23/02 specially adapted for optimising the efficiency at low load

Abstract

A system and method are provided for constant loading in AC power applications where at least one turn-on point of at least one half cycle of a modulating sine wave is randomly selected; at least one turn-off point is determined; and at least one slice located between the at least one turn-on point and turn-off point is removed. The slices may be removed by utilizing insulated gate bipolar transistors or field effect transistors.

Claims

1. A method for providing constant loading in AC power applications using a modulating sine wave having a constant first root mean squared voltage and positive half cycles and negative half cycles, said method comprising the steps of:

selecting randomly a plurality of turn-on points along said modulating sine wave, wherein each of said turn-on points is paired with a turn-off point that immediately precedes said turn-on point, and wherein said selection of said turn-on points is made via at least one insulated gate bipolar transistor;

determining said turn-off points;

removing slices from said modulating sine wave wherein each of said slices is between one of said pairs of turn-off points and turn-on points;

reducing said constant first root mean squared voltage to a constant second root mean squared voltage during said step of removing;

controlling said positive half cycles with a first IGBT device;

controlling said negative half cycles with a second IGBT device;

routing said positive half cycles to said first IGBT device with a first diode connected across said first IGBT device; and

routing said negative half cycles to said second IGBT device with a second diode connected across said second IGBT device;

wherein a first IGBT shunt control transistor is placed in a shunt configuration with said first IGBT device, and

wherein a second IGBT shunt control transistor is placed in a shunt configuration with said second IGBT device.

2. The method of claim 1, wherein a third diode is connected across said first IGBT shunt control transistor, and

wherein a fourth diode is connected across said second IGBT shunt control transistor.

3. The method of claim 2, further comprising the steps of:

modulating said positive half cycles with said first IGBT device and said first diode, and

clamping an opposite polarity voltage resulting from an electromagnetic field during said step of modulating with said first IGBT shunt control transistor and said third diode.

4. The method of claim 3, further comprising the steps of:

modulating said negative half cycles with said second IGBT device and said second diode, and

clamping an opposite polarity voltage resulting from an electromagnetic field during said step of modulating said negative half cycles with said second IGBT shunt control transistor and said fourth diode.

5. The method of claim 4, wherein a first transorb device is connected across said first and second IGBT devices, and

wherein a second transorb device is connected across said first and second IGBT shunt control transistors.

6. The method of claim 4, further comprising the step of:

clamping a spike during a switching transition with a first transorb device connected across said first and second IGBT devices.

7. The method of claim 6, further comprising the step of:

clamping a mains bourne transient signal with said first transorb device.

8. A method for providing constant loading in AC power applications using a modulating sine wave having a constant first root mean squared voltage and positive half cycles and negative half cycles, said method comprising the steps of:

selecting randomly a plurality of turn-on points along said modulating sine wave, wherein each of said turn-on points is paired with a turn-off point that immediately precedes said turn-on point, and wherein said selection of said turn-on points is made via at least one field effect transistor;

determining said turn-off points;

removing slices from said modulating sine wave wherein each of said slices is between one of said pairs of turn-off points and turn-on points;

reducing said constant first root mean squared voltage to a constant second root mean squared voltage during said step of removing;

controlling said positive half cycles with a first FET device;

controlling said negative half cycles with a second FET device;

routing said positive half cycles to said first FET device with a first diode connected across said first FET device; and

routing said negative half cycles to said second FET device with a second diode connected across said second FET device;

wherein a first FET shunt control transistor is placed in a shunt configuration with said first FET device, and

wherein a second FET shunt control transistor is placed in a shunt configuration with said second FET device.

9. The method of claim 8, wherein a third diode is connected across said first FET shunt control transistor, and

wherein a fourth diode is connected across said second FET shunt control transistor.

10. A system for providing constant loading in AC power applications comprising:

a modulating sine wave having a plurality of positive half cycles and negative half cycles and a constant first root mean squared voltage;

a means for selecting randomly a plurality of turn-on points along said positive half cycles of said modulating sine wave, wherein each of said turn-on points along said positive half cycles is paired with a turn-off point that immediately precedes said turn-on point;

a means for determining said turn-off points of said positive half cycles of said modulating sine wave;

a means for selecting randomly a plurality of turn-on points along said negative half cycles of said modulating sine wave, wherein each of said turn-on points along said negative half cycles is paired with a turn-off point that immediately precedes said turn-on point;

a means for determining said turn-off points of said negative half cycles of said modulating sine wave;

a means for removing slices from said positive half cycles of said modulating sine wave wherein each of said slices is between one of said pairs of turn-off points and turn-on points; and

a means for removing slices from said negative half cycles of said modulating sine wave wherein each of said slices is between one of said pairs of turn-off points and turn-on points,

wherein said turn-off points of said positive half cycles and said turn-off points of said negative half cycles are determined so as to reduce said constant first root mean squared voltage to a constant second root mean squared voltage,

wherein said means for removing slices from said positive half cycles comprises a first IGBT device, and said means for removing slices from said negative half cycles comprises a second IGBT device,

wherein a first diode is connected across said first IGBT device and is configured to rout said positive half cycles to said first IGBT device, and a second diode is connected across said second IGBT device and is configured to rout said negative half cycles to said second IGBT device, and

wherein a first IGBT shunt control transistor is placed in shunt configuration with said first IGBT device, and a second IGBT shunt control transistor is placed in a shunt configuration with said second IGBT device.

11. The system of claim 10, wherein a third diode is connected across said first IGBT shunt control transistor, and

wherein a fourth diode is connected across said second IGBT shunt control transistor.

12. The system of claim 11, wherein a first transorb device is connected across said first and second IGBT devices, and

wherein a second transorb device is connected across said first and second IGBT shunt control transistors.

13. A system for providing constant loading in AC power applications comprising:

a modulating sine wave having a plurality of positive half cycles and negative half cycles and a constant first root mean squared voltage;

a means for selecting randomly a plurality of turn-on points along said positive half cycles of said modulating sine wave, wherein each of said turn-on points along said positive half cycles is paired with a turn-off point that immediately precedes said turn-on point;

a means for determining said turn-off points of said positive half cycles of said modulating sine wave;

a means for selecting randomly a plurality of turn-on points along said negative half cycles of said modulating sine wave, wherein each of said turn-on points along said negative half cycles is paired with a turn-off point that immediately precedes said turn-on point;

a means for determining said turn-off points of said negative half cycles of said modulating sine wave;

a means for removing slices from said positive half cycles of said modulating sine wave wherein each of said slices is between one of said pairs of turn-off points and turn-on points; and

a means for removing slices from said negative half cycles of said modulating sine wave wherein each of said slices is between one of said pairs of turn-off points and turn-on points,

wherein said turn-off points of said positive half cycles and said turn-off points of said negative half cycles are determined so as to reduce said constant first root mean squared voltage to a constant second root mean squared voltage,

wherein said means for removing slices from said positive half cycles comprises a first FET device, and said means for removing slices from said negative half cycles comprises a second FET device,

wherein a first diode is connected across said first FET device and is configured to rout said positive half cycles to said first FET device, and a second diode is connected across said second FET device and is configured to rout said negative half cycles to said second IGBT device, and

wherein a first FET shunt control transistor is placed in shunt configuration with said first FET device, and a second FET shunt control transistor is placed in a shunt configuration with said second FET device.

14. The system of claim 13, wherein a third diode is connected across said first FET shunt control transistor, and

wherein a fourth diode is connected across said second FET shunt control transistor.

15. The system of claim 14, wherein a first transorb device is connected across said first and second FET devices, and

wherein a second transorb device is connected across said first and second FET shunt control transistors.

16. A system for providing constant loading in AC power applications comprising:

a means for polling at least one motor controller in a network configuration to determine a consumption level of power;

a means for grouping said at least one motor controller according to said consumption level of power;

at least one modulating sine wave applied to said at least one motor controller having at least one positive half cycle and at least one negative half cycle and a constant first root mean squared voltage;

a means for selecting randomly at least one turn-on point of said at least one positive half cycle of said at least one modulating sine wave applied to said at least one motor controller;

a means for determining at least one turn-off point of said at least one positive half cycle of said at least one modulating sine wave applied to said at least one motor controller;

a means for selecting randomly at least one turn-on point of said at least one negative half cycle of said at least one modulating sine wave applied to said at least one motor controller;

a means for determining at least one turn-off point of said at least one negative half cycle of said at least one modulating sine wave applied to said at least one motor controller;

a means for removing at least one slice located under said at least one positive half cycle of said modulating sine wave applied to said at least one motor controller wherein said at least one slice is an area under said at least one positive half cycle between said at least one turn-off point and said at least one turn-on point; and

a means for removing at least one slice located under said at least one negative half cycle of said modulating sine wave applied to said at least one motor controller wherein said at least one slice is an area under said at least one negative half cycle between said at least one turn-off point and said at least one turn-on point,

wherein said at least one turn-off point of said at least one positive half cycle and said at least one turn-off point of said at least one negative half cycle are determined so as to reduce said constant first root mean squared voltage to a constant second root mean squared voltage,

wherein said means for removing slices from said positive half cycles comprises a first IGBT device, and said means for removing slices from said negative half cycles comprises a second IGBT device,

wherein a first diode is connected across said first IGBT device and is configured to rout said positive half cycles to said first IGBT device, and a second diode is connected across said second IGBT device and is configured to rout said negative half cycles to said second IGBT device,

wherein a first IGBT shunt control transistor is placed in shunt configuration with said first IGBT device, and a second IGBT shunt control transistor is placed in a shunt configuration with said second IGBT device.

17. The system of claim 16, wherein a third diode is connected across said first IGBT shunt control transistor, and

wherein a fourth diode is connected across said second IGBT shunt control transistor.

18. The system of claim 17, wherein a first transorb device is connected across said first and second IGBT devices, and

wherein a second transorb device is connected across said first and second IGBT shunt control transistors.