Electricity: power supply or regulation systems – Output level responsive
Reexamination Certificate
1999-10-22
2001-01-30
Wong, Peter S. (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
C323S909000, C320S117000, C320S101000
Reexamination Certificate
active
06181115
ABSTRACT:
The present invention relates to a device for generating electrical energy for a power supply bus, in particular a regulated bus of the kind used on board satellites.
BACKGROUND OF THE INVENTION
Such devices provide the best results for a minimum area of solar sensor and a minimum mass of batteries. Such regulated buses at 50 V or indeed at 100 V are used for geostationary telecommunications satellites and are presently implemented for constellations of satellites such as SKYBRIDGE or indeed CELESTRI/TELEDESIC.
At present, there exist several known architectures for powering a bus from a solar energy generator and from an electrical energy storage unit comprising one or more batteries.
The first concept implements three operating domains, specifically shunt control of excess solar energy generated at a given instant (via a short circuit), charging the energy storage unit, and discharging the energy storage unit. The operating domains are controlled by a control loop which governs the transition between modes and which manages conflicts between operating modes (for example charging and discharging the battery(ies)). That concept requires both a battery charge regulator and a battery discharge regulator to be implemented.
A second concept implements two operating domains, specifically shunt control and discharge of the battery(ies). The charge regulator is not controlled by the control loop, and operation thereof is simplified, however it is no longer possible to manage conflicts.
In a third known concept, referred to as a “hybrid bus”, the solar generators are subdivided into two groups, one of which is allocated to powering the bus and the other to charging the batteries. This makes it possible to omit the charge regulator, but operation is not optimized and it turns out to be sensitive to failures in the solar generators.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention relates to an electrical energy generator device for a power supply bus that makes it possible:
in practice to ensure that operation takes place correctly in all three above-mentioned domains; and
to avoid implementing a charge regulator of the kind that is to be found in prior art devices.
In other words, the problem posed by the invention is that of conserving operation over three domains while simplifying the architecture of the device.
The idea on which the invention is based is to allocate each of the modules constituting the energy generator either to powering the bus or to charging the battery(ies), or to being short circuited to dump excess energy, depending on requirements, with the modules being individually controllable for this purpose to take up each of the three states.
The invention thus provides a device for generating electrical energy for a power supply bus connected to a load, and comprising:
a) an electrical energy storage unit comprising at least one battery;
b) a solar energy generator presenting a plurality of modules;
c) a regulator for controlling discharging of the storage unit to power said bus from the storage unit, the device including:
d) for each module, a three-state control device presenting:
i) a first state in which the current from said module powers the bus;
ii) a second state in which the current from said module powers the storage unit; and
iii) a third state in which said module is short circuited; and
e) a control unit for causing the control devices to take up one of their three states.
In general, each module constitutes a section having a plurality of elementary generators.
In general, the power supply bus presents a capacitive element.
In an advantageous variant, the control unit has a control state for subdividing the control modules in two groups, namely:
i) a first group in which at least one module is in its first state to power the bus, and in which one of the modules is allocated to regulating the bus voltage, and is for this purpose in its first state only while the maintenance of a nominal voltage on the bus requires current to be delivered from said module; and
ii) a second group in which at least one module is either in its second state, or else in its third state, as a function of a desired level of charging current, the number of modules in the second state being a function of the desired charging current value.
When maintaining the nominal voltage of the bus does not require current to be supplied from said module, it can be placed in its third state, and preferably it is placed in its second state if the level of said charging current makes that possible, and in its third state otherwise.
A charging control device can generate said value of charging current desired for the electrical energy storage unit. It preferably has an output for an end-of-charging logic signal so as to place at least some of the modules forming a portion of the second group into the third state.
In a preferred embodiment, the modules are connected to the bus via a forwardly-conductive diode, and to the electrical energy storage unit via a controlled switch and a forwardly-conductive diode, closure of the controlled switch placing the module in its second state.
Finally, the invention provides the above-specified device in a system for which the final charging voltage of the storage unit is significantly lower than the nominal voltage of the bus.
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Haines James Edward
Olsson Dan
Perol Philippe Alfred
Agence Spatiale Europeenne
Sughrue Mion Zinn Macpeak & Seas, PLLC
Vu Bao Q.
Wong Peter S.
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