Battery regulated bus spacecraft power control system

A solar power supply system of the type containing a rechargeable battery clamping a power bus, comprising:

• a plurality of DC power sources, each of said DC power sources comprising a solar panel and a computer controlled variable transconductance means connected in electrical series circuit to said power bus and to said rechargeable battery;
• said solar panel producing DC voltage responsive to sunlight and said variable transconductance means, associated with said solar panel, passing DC current produced by said solar panel in dependence upon the transconductance value to which said variable transconductance means is set;
• and
• digital computer means for individually controlling said transconductance value of each said variable transconductance means of said plurality of DC power sources, whereby said digital computer means controls DC electrical power flowing into said power bus, and DC current from said power bus flows into said rechargeable battery:
• computer readable battery current sensor means for monitoring current into and from said battery, said battery current sensor means being periodically read by said digital computer means for permitting said digital computer means to compute the state of charge of said rechargeable battery;
• said digital computer means including program means for prescribing transconductance levels for each of said variable transconductance means responsive to said state of charge of said rechargeable battery;
• and means for periodically adjusting said transconductance level of at least one of said variable transconductance means that is supplying current to said power bus to a transconductance level falling between low transconductance and high transconductance so long as said battery current sensor means does not detect a prescribed value of battery current, while maintaining the remainder of said variable transconductance means that are also supplying current to said power bus at high transconductance, and wherein said prescribed value of battery current is a full charge current prescribed for said rechargeable battery and wherein said computer readable battery current sensor means comprises:
• a first magnetic amplifier type current sensor, said first magnetic amplifier type current sensor containing a magnetic core, a first winding for receiving current to be measured, and an output winding for producing an output voltage, Vrdg1, in dependence upon current through said first winding and a predetermined sensor gain slope of G.sub.1 ;
• a second magnetic amplifier type current sensor, said second magnetic amplifier type current sensor containing a magnetic core, a first winding for receiving current to be measured, a bias winding and an output winding for producing an output voltage, Vrdg.sub.2, in dependence upon current through said first winding and said bias winding and a predetermined sensor gain slope of G.sub.2 ;
• means coupling said first winding of each of said first and second magnetic amplifier type current sensors in electrical series circuit to an electrical load, whereby current to said electrical load passes through both said first windings;
• means providing a dc bias current in said bias winding of said second current sensor only to produce an offset current X for said second magnetic amplifier type current sensor;
• means for reading the output voltage of each of said first and second magnetic amplifier type current sensors in quick succession to provide two voltage readings, Vrdg.sub.1 and Vrdg.sub.2, said respective voltage readings being representative of the respective load current through said first winding of each said first and second magnetic amplifier type current sensors, respectively;
• correlation means for correlating said two voltage readings, said correlation means comprising:
• first means for computing first and second potential load current values from said two voltage readings, Vrdg.sub.1 and Vrdg.sub.2 according to the following equation 1-1;
• Current (+)=(Vrdg-Voff).times.G, 1-1
• where
• Vrdg is said voltage reading at said respective sensor output,
• Voff is the offset voltage, where
• Voff=X/G, and
• X is said respective sensor offset current,
• G is said sensor gain slope;
• second means for computing third and fourth potential load current values from said two voltage readings, Vrdg.sub.1 and Vrdg.sub.2 according to the following equation 1-2:
• Current(-)=-(Vrdg+Voff).times.G, 1-2
• where Vrdg is a positive number;
• and
• means for defining a predefined error band of differences in current values;
• means for determining the difference between said first and second computed current values;
• means for determinging the difference between said third and fourth computed current values;
• means for determining the absolute value of said first and second differences and comparing said absolute vaules to determine which of said absolute values yields the smallest difference;
• means for selecting said smallest difference in absolute values and determining whether such difference falls within said error band and, if not falling within said error band, then selecting the next difference computation and determining whether said next difference computation falls within said error band;
• means responsive to selection of said difference computation that falls within said error band for providing an output signal representative of one of said two current values used to determine said difference computation that falls within said error band, whereby said output signal comprises an indication of load current magnitude.

In a power supply system for supplying dc power over a power bus to an electrical load, said system including adc current generating means coupled to said power bus for supplying current to said electrical load with said generating means being interruptable, a rechargeable battery coupled to said power bus for supplying dc current to said bus in the absence of current from said dc current generating means, whereby electrical charge stored in said battery is depleted and receiving charging current from said dc current generating means over said power bus, whereby electrical charge in said battery is replenished, the improvement comprising:

• stored program computer means, including a program, for regulating the rate of charge of said battery from between a maximum allowable charge rate and a trickle charge rate in dependence upon the amount of electrical charge depleted from said battery during any prior period of time during which said battery was supplying current to said power bus;
• current monitoring means for monitoring electrical current exiting said battery and supplying information thereon to said computer;
• said computer integrating said information in accordance with said stored program to determine the electrical charge depleted by said battery and the amount of electrical charge required thereby to replenish said charge in said battery;
• and
• computer controlled regulator means coupled between said power bus and said dc current generating means for regulating the level of current applied from said dc current generating means to said bus, said computer controlled regulator means being controlled by said stored program computer means to cause said generating means to provide current levels prescribed by said program over time intervals prescribed by said program to supply electrical current required by said electrical load and specified levels of charging current to recharge said battery.

In a power supply system for supplying dc power to an electrical load over a power bus, said power supply system including generating means coupled to said power bus for supplying current to said electrical load with said generating means being of an interruptable characteristic;

• a rechargeable battery coupled to said power bus for supplying dc current to said power bus during interruption of said generating means, whereby charge stored in said rechargeable battery is depleting, and alternately for receiving dc charging current from said generating means over said bus, whereby charge depleted from said rechargeable battery is replenished;
• the improvement comprising:
• stored program computer means, including a program, for regulating the rate of charge of said rechargeable battery from between a maximum rate and a trickle charge in dependence upon the amount of charge depleted from said battery during any interval in which said battery supplied dc current to said power bus;
• current monitoring means for monitoring the current discharged from said battery and supplying information thereon to said stored program computer means, said stored program computer means checking said current monitoring means in accordance with said stored program and integrating such information in accordance with said stored program to determine the amount of charge depleted from said battery;
• and
• computer controlled regulator means coupled between said power bus and said generating means for regulating the instantaneous level of dc current applied from said generating means to said bus, said computer controlled regulator means being controlled by said computer to cause said generating means to provide prescribed current levels for prescribed increments of time prescribed by said stored program, responsive to less than full charge in said rechargeable battery, to provide current to said load and full charge current to said rechargeable battery and, responsive to said battery attaining a full state of charge, to supply current required by said load and a trickle current required by said rechargeable battery.

A computer controlled solar array type electrical supply system for converting solar energy to electricity and supplying such electricity to an electrical load requiring a predetermined load current, comprising:

• a plurality of M solar panels, M being a number greater than two;
• a plurality of M buck converters, each of said buck converters being associated with a corresponding one of said solar panels to form a plurality of solar panel and buck converter combinations, with each of said solar panel and buck converter combinations being adapted to be selectively connected in common to an electrical load to supply current thereto;
• means for selecting K panels from amongst said M solar panels, where K is a number equal to or less than the quantity M, and applying an output of each said selected solar panel and buck converter combinations to said electrical load for supplying current to said electrical load and leaving any remainder of said solar panel and buck converter combinations in reserve, effectively disconnected from said electrical load;
• means for programming a plurality of N of said buck converters from within said group of K solar panel and buck converter combinations to each produce a high current output, said plurality N being no greater than the number (K-1);
• means for programming one of said buck converters from within the remaining K-N solar panel and buck converter combinations to produce a low current output;
• and
• wherein the sum of said high current outputs from said N Buck converters and said low currrent output of said one Buck converter equals said predetermined load current.

A computerized solar array electrical supply system, comprising:

• A plurality of M solar panels;
• a plurality of M programmable Buck converters, each of said buck conveters being associated with a corresponding one of said solar panels to form a plurality of solar panel and buck converter combinations, with each of said solar panel and buck converter combinations being adapted to be selectively connected in common to an electrical load;
• said Buck converters having a programmable duty cycle and in which the transconductance thereof is variable as a dependent function of the duty cycle;
• means for periodically determining the load demand current of said electrical load;
• means for periodically calculating the number of solar panel and buck converter combinations, K, where K is equal to or less than the quantity M, required to produce said load demand current;
• means for periodically selecting said K panels from amongst said M solar panels and applying an output of each said selected solar panel and buck converter combinations in common to said electrical load for supplying current thereto and leaving any remainder, M-K, of said solar panel and buck converter combinations in reserve inhibited from supplying current to said electrical load;
• means for programming a plurality of N of said buck converters from within said selected K solar panel and buck converter combinations to each produce a high current output, said plurality N being no greater than the number (K-1);
• and
• means for programming one of said buck converters from within the remaining ones of said selected K solar panel and buck converter combinations to produce a low current output.

An electrical current sensor for providing an indication of load current magnitude and direction, said current sensor having wide dynamic range comprising:

• a first magnetic amplifier type current sensor, said first magnetic amplifier type current sensor containing a magnetic core, a first winding for receiving current to be measured, and an output winding for producing an output voltage, Vrdg1, in dependence upon current through said first winding and a predetermined sensor gain slope of G;
• a second magnetic amplifier type current sensor, said second magnetic amplifier type current sensor containing a magnetic core, a first winding for receiving current to be measured, a bias winding and an output winding for producing an output voltage, Vrdg2, in dependence upon current through said first winding and said bias winding and a predetermined sensor gain slope of G;
• means coupling said first winding of each of said first and second magnetic amplifier type current sensors in electrical series circuit to an electrical load, whereby current to said electrical load passes through both said first windings;
• means providing a dc bias current in said bias winding of said second magnetic amplifier type current sensor only to produce an offset current X for said second magnetic amplifier type current sensor;
• means for contemporaneously reading the output voltage of each of said first and second magnetic amplifier type current sensor to provide two voltage readings, Vrdg.sub.1 and Vrdg.sub.2, said respective voltage readings being representative of the respective load current through said first winding of each said first and second magnetic amplifier type current sensors, respectively;
• means for computing first and second potential load current values from said two voltage readings, Vrdg.sub.1 and Vrdg.sub.2 according to the following equation 1--1;
• Current (+)=(Vrdg-Voff).times.G, 1--1
• where
• Vrdg is said respective DC voltage read at the sensor output from said respective output winding,
• Voff is an offset voltage, where
• Voff=X/G, and
• X is said magnetic amplifier type current sensor offset current,
• G is said magnetic amplifier type sensor gain slope in amps per volt;
• means for computing third and fourth potential load current values from said two voltage readings, Vrdg1 and Vrdg2, according to the following equation 1-2:
• Current(-)=-(Vrdg+Voff).times.G, 1-2
• where Vrdg is a positive number;
• and
• means for selecting the two respective computations of said load current from amongst said four computed values that are essentially equal in value as the indication of load current magnitude.

A computer assisted electrical current sensor for providing an indication of load current magnitude and direction, said current sensor having a wide dynamic range, comprising:

• a first magnetic amplifier type current sensor, said first magnetic amplifier type current sensor containing a magnetic core, a first winding for receiving current to be measured, and an output winding for producing an output voltage, Vrdg1, in dependence upon current through said first winding and a predetermined sensor gain slope of G.sub.1 ;
• a second magnetic amplifier type current sensor, said second magnetic amplifier type current sensor containing a magnetic core, a first winding for receiving current to be measured, a bias winding and an output winding for producing an output voltage, Vrdg.sub.2, in dependence upon current through said first winding and said bias winding and a predetermined sensor gain slope of G.sub.2 ;
• means coupling said first winding of each of said first and second magnetic amplifier type current sensors in electrical series circuit to an electrical load, whereby current to said electrical load passes through both said first windings;
• means providing a dc bias current in said bias winding of said second current sensor only to produce an offset current X for said second magnetic amplifier type current sensor;
• means for contemporaneously reading the output voltage of each of said first and second magnetic amplifier type current sensor to provide two voltage readings, Vrdg.sub.1 and Vrdg.sub.2, said respective voltage readings being representative of the respective load current through said first winding of each said first and second magnetic amplifier type current sensors, respectively;
• correlation means for correlating said two voltage readings, said correlation means comprising:
• first means for computing first and second potential load current values from said two voltage readings, Vrdg.sub.1 and Vrdg.sub.2 according to the following equation 1-1;
• Current (+)=(Vrdg-Voff).times.G, 1--1
• where
• Vrdg is said voltage reading at said respective sensor output,
• Voff is the offset voltage, where
• Voff=X/G, and
• X is said respective sensor offset current,
• G is said sensor gain slope;
• second means for computing third and fourth potential load current values from said two voltage readings., Vrdg.sub.1 and Vrdg.sub.2 according to the following equation 1-2:
• Current(-)=-(Vrdg+Voff).times.G, 1-2
• where Vrdg is a positive number;
• and;
• third means for defining a predefined error band of differences in current values;
• fourth means for determining the difference between said first and second computed current values;
• fifth means for determinging the difference between said third and fourth computed current values;
• sixth means for determining the absolute value of said first and second differences and comparing said absolute vaules to determine which of said absolute values yields the smallest difference;
• seventh means for selecting said smallest difference in absolute values and determining whether such difference falls within said error band and, if not falling within said error band, then selecting the next difference computation and determining whether said next difference computation falls within said error band;
• eighth means responsive to selection of said difference computation that falls within said error band for providing an output signal representative of one of said two current values used to determine said difference computation that falls within said error band, whereby said output signal comprises an indication of load current magnitude.