Dynamic feedback adaptive control system and method for paralleling electric power sources and an uninterruptible power supply including same
First Claim
1. A method of controlling a first electrical power source, the first electrical power source being in parallel operation with at least one other electrical power source to supply an electrical load, the method comprising the steps of:
- generating a desired reference voltage signal;
sensing an output voltage generated by the first electrical power source;
sensing an output current generated by the first electrical power source; and
compensating the desired reference voltage signal with an integration of the sensed output voltage and a proportion of the sensed output current to maintain proper division of the electrical load on a per unit basis.
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Accused Products
Abstract
A connectionless paralleling and load sharing system and method for power sources are presented. The invention provides a dynamic feedback adaptive control system that enables proper load sharing among paralleled power sources without the need for interconnection therebetween. Only the individual source'"'"'s voltage and current are sensed by its controller. These output parameters are then used to modify a reference voltage used by the controller to control the source'"'"'s output waveform. This reference voltage compensation is accomplished through two feedback control loops, an outer loop for the voltage compensation and an inner loop for the current compensation. The outer loop includes an integration of the voltage error between the desired voltage and the actual voltage sensed at the source'"'"'s output. The inner loop is filtered and operates in a proportional fashion to rapidly adjust the output. Through proper constant selection the control system and method of the invention provides load sharing control proportional to an individual source'"'"'s power supplying capacity, i.e. on a per unit basis. This allows the use of supplies of different rating in a single paralleled environment. This system and method are particularly well suited for systems requiring uninterruptible power supplies.
107 Citations
19 Claims
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1. A method of controlling a first electrical power source, the first electrical power source being in parallel operation with at least one other electrical power source to supply an electrical load, the method comprising the steps of:
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generating a desired reference voltage signal;
sensing an output voltage generated by the first electrical power source;
sensing an output current generated by the first electrical power source; and
compensating the desired reference voltage signal with an integration of the sensed output voltage and a proportion of the sensed output current to maintain proper division of the electrical load on a per unit basis.
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2. A method of controlling a first electrical power source, the first electrical power source being in parallel operation with at least one other electrical power source to supply an electrical load, the method comprising the steps of:
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generating a desired reference voltage signal;
sensing an output voltage generated by the first electrical power source;
sensing an output current generated by the first electrical power source; and
compensating the desired reference voltage signal with only the sensed output voltage and the sensed output current to maintain division of the electrical load on a per unit basis; and
wherein the step of compensating comprises the steps of;
calculating a difference between a magnitude of the reference voltage signal and the sensed output voltage;
integrating the difference;
adding a constant selected based on a power capacity of the first electrical power source;
multiplying a result of said step of adding by the reference voltage signal;
subtracting the sensed output current to develop a compensation signal; and
adding the compensation signal to the reference voltage signal. - View Dependent Claims (3)
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4. A method of controlling an electrical power source, the electrical power source being in parallel operation with at least one other electrical power source to supply an electrical load, the method comprising the steps of:
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generating a desired reference voltage signal;
sensing an output voltage generated by the electrical power source;
sensing an output current generated by the electrical power source; and
compensating the desired reference voltage signal with only the sensed output voltage and the sensed output current to maintain proper division of the electrical load on a per unit basis; and
wherein the step of compensating comprises the step of calculating a compensated reference signal to control the output of the electrical power source in accordance with the following equation;
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5. A method of controlling an electrical power source, the electrical power source being in parallel operation with at least one other electrical power source to supply an electrical load, the method comprising the steps of:
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generating a desired reference voltage signal;
sensing an output voltage generated by the electrical power source;
sensing an output current generated by the electrical power source; and
compensating the desired reference voltage signal with only the sensed output voltage and the sensed output current to maintain proper division of the electrical load on a per unit basis; and
wherein said step of compensating comprises the step of utilizing a fast current compensation loop and a slow voltage compensation loop. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. An electrical source capable of operating in parallel with other electrical power sources to supply a connected electrical load, comprising:
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an output voltage generator producing an output voltage and an output current; and
a controller calculating a reference control signal in a connectionless manner, the reference control signal used by the output voltage generator to control the output such that the electrical source supplies an amount of the connected electrical load in proportion to a total power capacity of the electrical source, said controller further calculating said reference control signal by sensing only said output voltage and said output current, said controller including a dynamic feedback adaptive control system utilizing said output voltage and said output current to compensate a desired voltage reference signal to achieve said reference control signal; and
wherein said dynamic feedback adaptive control system includes a slow voltage control loop and a fast current control loop, said slow voltage control loop integrating a difference between said output voltage and said desired voltage reference signal, and said fast current control loop providing proportional compensation that is inversely proportional to said output current. - View Dependent Claims (13, 14)
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15. An electrical source capable of operating in parallel with other electrical power sources to supply a connected electrical load, comprising:
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an output voltage generator producing an output voltage and an output current; and
a controller calculating a reference control signal in a connectionless manner, the reference control signal used by the output voltage generator to control the output such that the electrical source supplies an amount of the connected electrical load in proportion to a total power capacity of the electrical source, said controller further calculating said reference control signal by sensing only said output voltage and said output current, said controller including a dynamic feedback adaptive control system utilizing said output voltage and said output current to compensate a desired voltage reference signal to achieve said reference control signal; and
wherein said dynamic feedback adaptive control system calculates said reference control signal in accordance with the following equation;
- View Dependent Claims (16, 17, 18)
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19. A dynamic adaptive feedback controller for a first electrical power source, the first electrical power source being capable of supplying electric power in parallel with at least one other at least one power sources to a connected electrical load, comprising:
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a desired reference waveform generator;
an output voltage sense circuit coupled to an output of the first electrical power source;
an output current sense circuit coupled to the output of the first electrical power source; and
wherein the controller utilizes a slow voltage feedback loop and a fast current feedback loop to maintain load division on a per unit basis in a connectionless manner with the at least one other power sources.
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Specification