Electric power conversion systems – Current conversion – Having plural converters for single conversion
Reexamination Certificate
1999-07-12
2001-01-30
Sterrett, Jeffrey (Department: 2838)
Electric power conversion systems
Current conversion
Having plural converters for single conversion
C363S017000, C363S132000
Reexamination Certificate
active
06181585
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to an ion propulsion system, and in particular to a method and apparatus for supplying electrical power to an ion engine.
BACKGROUND OF THE INVENTION
For over thirty years, ion engines have been proposed for propulsion of vehicles in space. Outside of space propulsion, ion generation may also be applied to various types of materials processing systems involving ion sources, such as for ion beam etching or micromachining. Ion engines use movement of ions to provide thrust.
Generally, an ion engine has an ion accelerator system that uses an anode, a cathode, a screen grid and an accelerator grid coupled within a thruster housing. Generally, an ion engine works by generating an inert gas plasma within the thruster housing. Xenon is an example of a suitable gas. A charge within the plasma between the anode and cathode forms ions. The inert gas ions leave the thruster through the charged screen and accelerator. The net force from the ions leaving the thruster housing generates a thrust. A neutralizer is located outside the thruster housing and generates electrons. The electrons are attracted to the ions so the ions do not re-enter the thruster housing as they otherwise would in space.
A number of power supplies are used to power the various components of the system. Heaters, the accelerator, the screen, the anode and cathode of the thruster, and the anode and cathode of the neutralizer each have separate power supplies. The power supply for the screen processes a majority of the power of the spacecraft. The anode and cathode of the thruster also a substantial amount of power. The remaining four power supplies use a relatively little amount of power (less than 100 Watts).
Although the four power supplies use little power they account for a significant amount of parts and complexity. In spacecraft design, it is desirable to eliminate parts and complexity when possible. More parts increases weight of the spacecraft. More parts and complexity inherently reduces reliability.
It is therefore an object of the invention to provide a power supply system that operates reliably while maintaining good efficiency over the dynamic range.
SUMMARY OF THE INVENTION
It is therefore one object of the invention to provide a power supply system that operates reliably over a wide dynamic range. It is a further object of the invention to provide a module that is capable of operating at lower power and lower stress levels as well as higher power and high stress levels and that spreads power distribution over a large area to reduce stress.
In one aspect of the invention, a power supply circuit for an ion engine suitable for a spacecraft is coupled to a bus having a bus input and a bus return. The power supply circuit has a first primary winding of a first transformer. An upper inverter circuit is coupled to the bus input and the first primary winding. The power supply circuit further includes a first lower inverter circuit coupled to the bus return and the first primary winding. The second primary winding of a second transformer is coupled to the upper inverter circuit. A second lower inverter circuit is coupled to the bus return and the second primary winding.
In a further aspect of the invention, a method for controlling a power supply circuit having an upper inverter circuit, a first lower inverter circuit, and a second lower inverter circuit, said first lower inverter circuit and said second lower inverter circuit coupled to the upper inverter circuit, the method comprising the steps of:
controlling a first lower inverter circuit using a first output signal of a pulse width modulating circuit, said first output signal having a first duty cycle;
increasing the first duty cycle to attain a first predetermined voltage;
controlling a second lower inverter circuit using a second output signal of a pulse width modulating circuit, said second output signal having a second duty cycle; and
increasing the second duty cycle to attain a second predetermined voltage independent of the first predetermined voltage.
One advantage of the invention is that independent control of the individual power supplies is maintained. This has been achieved using a reduce part count.
Other features and advantages of the invention are readily apparent from the following detailed description of carrying out the invention when taken in connection with the accompanying drawings.
REFERENCES:
patent: 3491250 (1970-01-01), Shoh
patent: 4533836 (1985-08-01), Carpenter et al.
patent: 4695933 (1987-09-01), Nguyen et al.
patent: 4825646 (1989-05-01), Challoner et al.
patent: 5269131 (1993-12-01), Brophy
patent: 5369953 (1994-12-01), Brophy
patent: 5434770 (1995-07-01), DreiFuerst et al.
patent: 5451962 (1995-09-01), Steigerwald
patent: 5576940 (1996-11-01), Steigerwald et al.
patent: 5610452 (1997-03-01), Shimer et al.
patent: 5657217 (1997-08-01), Watanabe et al.
patent: 5666278 (1997-09-01), Ng et al.
patent: 5852555 (1998-12-01), Martin
patent: 5862041 (1999-01-01), Martin
patent: 5862042 (1999-01-01), Jiang
patent: 5875103 (1999-02-01), Bhagwat et al.
patent: 5923549 (1999-07-01), Kobayashi et al.
patent: 5930122 (1999-07-01), Moriguchi et al.
patent: 5949668 (1999-09-01), Schweighofer
patent: 5991179 (1999-11-01), Schweighofer
Thomas A. Bond et al., “NSTAR Ion Engine Power Processor Unit Performance: Ground Test and Flight Experience”, SAE Paper 99APSC-47, Apr. 1999.
Thomas A. Bond et al., “The NSTAR Ion Propulsion Subsystem for DS1”, AIAA Joint Propulsion Conference, AIAA Paper 99-2972, Jun. 23, 1999.
John A. Hamley et al., “The Design and Performance Characteristics of the NSTAR PPU and DCIU”, AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 34th, Cleveland, OH, Jul. 13-15, 1998, AIAA Paper 98-3938.
Cardwell, Jr. Gilbert I.
Phelps Thomas K.
Gudmestad Terje
Hughes Electronics Corporation
Sterrett Jeffrey
LandOfFree
Multiple output power supply circuit for an ion engine with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiple output power supply circuit for an ion engine with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiple output power supply circuit for an ion engine with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2555265