1. A three-phase rectifier that converts three-phase alternating current (AC) power supplied from a three-phase AC power supply into direct current (DC) power, the three-phase rectifier comprising:
a full-wave rectifier circuit that rectifies the three-phase AC power to the DC power;
a bidirectional switch circuit that switches on and off inputs of respective phases from the three-phase AC power supply to the full-wave rectifier circuit; and
a controller that detects voltages of the respective phases of the three-phase AC power supply, generates switching patterns for the respective phases to switch the bidirectional switch circuit on and off based on the voltages of the phases, and controls switching of the bidirectional switch circuit based on the switching patterns, wherein
the switching patterns for the respective phases have a predetermined switching cycle, and
the controller detects a maximum potential phase, an intermediate potential phase, and a minimum potential phase in the voltages of the respective phases of the three-phase AC power supply, and generates, for the maximum potential phase and the minimum potential phase, switching patterns for switching on for a time proportional to respective potentials, at least one of which is on in the switching cycle, and generates, for the intermediate potential phase, a switching pattern for switching on constantly.
2. The three-phase rectifier according to claim 1, wherein a capacitor is connected between the three-phase AC power supply and the bidirectional switch circuit.
3. The three-phase rectifier according to claim 2, wherein a DC reactor is connected between the full-wave rectifier circuit and a load.
4. The three-phase rectifier according to claim 1, wherein a DC reactor is connected between the full-wave rectifier circuit and a load.
5. A three-phase rectifier that converts three-phase alternating current (AC) power supplied from a three-phase AC power supply into direct current (DC) power, the three-phase rectifier comprising:
a full-wave rectifier circuit that rectifies the three-phase AC power to the DC power;
a bidirectional switch circuit that switches on and off inputs of respective phases from the three-phase AC power supply to the full-wave rectifier circuit; and
a controller that detects voltages of the respective phases of the three-phase AC power supply, generates switching patterns for the respective phases to switch the bidirectional switch circuit on and off based on the voltages of the phases, and controls switching of the bidirectional switch circuit based on the switching patterns, wherein
the controller divides one cycle of the three-phase AC power into a plurality of modes according to magnitude relation of the voltages of the respective phases,
the controller, in one mode of the plurality of modes, detects a maximum potential phase, an intermediate potential phase, and a minimum potential phase in the voltages of the respective phases of the three-phase AC power supply, and generates, for the maximum potential phase and the minimum potential phase, switching patterns for switching on for a time proportional to respective potentials, and generates, for the intermediate potential phase, a switching pattern for switching on when the pulse of either of the maximum potential phase or the minimum potential phase is on, and
the switching patterns have the same regularity for the same phase in all the plurality of modes.
6. The three-phase rectifier according to claim 5, wherein the switching patterns for the respective phases have a predetermined switching cycle, and
the controller introduces a period in which the bidirectional switch circuit is switched off for at least two phases in the switching cycle.
7. The three-phase rectifier according to claim 6, wherein the controller inserts zero voltage to a switching pattern for one phase.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A fiber web, comprising:
a plurality of cellulose fibers having an average fiber diameter between about 2 microns and about 75 microns and an average length between about 1 mm and about 15 mm;
a resin comprising a non-particulate acid scavenger; and
0-30 wt. % synthetic fibers.
2. A fiber web, comprising:
a plurality of cellulose fibers having an average fiber diameter between about 2 microns and about 75 microns and an average length between about 1 mm and about 15 mm;
0-30 wt. % synthetic fibers; and
an acid scavenger,
wherein the fiber web has a dry Mullen burst strength of greater than or equal to about 12 psi after being immersed in 150\xb0 C. synthetic oil for at least 168 hours.
3. A method of filtering a liquid, comprising:
passing a liquid across a fiber web, wherein the fiber web comprises:
a plurality of cellulose fibers having an average fiber diameter between about 2 microns and about 75 microns and an average length between about 1 mm and about 15 mm;
a resin comprising a non-particulate acid scavenger; and
0-30 wt. % synthetic fibers.
4. (canceled)
5. A fiber web as in claim 1, wherein the acid scavenger comprises a nitrogen.
6. A fiber web as in claim 1, wherein the acid scavenger comprises an amine.
7. A fiber web as in claim 1, wherein the acid scavenger is immobilized on the fiber web.
8. A fiber web as in claim 2, wherein the acid scavenger is a non-particulate acid scavenger.
9. A fiber web as in claim 1, wherein the solubility of the acid scavenger in water is greater than or equal to about 0.01 gmL.
10. A fiber web as in claim 1, wherein the acid scavenger is an organic molecule.
11. A fiber web as in claim 1, wherein the fiber web comprises greater than or equal to about 0.01 wt % and less than about 0.1 wt % acid scavenger.
12. A fiber web as in claim 1, wherein the fiber web comprises greater than or equal to about 40 wt. % of cellulose fibers.
13. A fiber web as in claim 1, wherein the fiber web has a dry Mullen burst strength of greater than or equal to about 12 psi after being immersed in 150\xb0 C. synthetic oil for at least 168 hours.
14. A fiber web as in claim 1, wherein the air permeability of the fiber web is between about 2 CFM and about 100 CFM.
15. A fiber web as in claim 1, wherein the dust holding capacity of the fiber web is between about 80 gm2 and about 500 gm2.
16-17. (canceled)
18. A filter element comprising the fiber web of claim 1.
19. A filter element comprising the fiber web of claim 2.
20. A fiber web as in claim 1, wherein the fiber web has a dry Mullen burst strength of greater than or equal to about 20 psi after being immersed in 150\xb0 C. synthetic oil for at least 68 hours.
21. A fiber web as in claim 1, wherein the fiber web comprises a residue of a binder fiber.
22. A fiber web as in claim 1, wherein the fiber web comprises an antioxidant.