Electrical transmission or interconnection systems – Plural supply circuits or sources – Substitute or emergency source
Reexamination Certificate
1999-03-18
2001-03-20
Ballato, Josie (Department: 2836)
Electrical transmission or interconnection systems
Plural supply circuits or sources
Substitute or emergency source
C318S150000
Reexamination Certificate
active
06204572
ABSTRACT:
FIELD OF INVENTION
This invention relates to rotating electric machines for electric power generation. More specifically, the invention relates to synchronous motors and generators as well as means for providing or furnishing a substantially instantaneous energy supply to a sensitive load in case that the electric utility fails to provide energy to the load.
BACKGROUND OF THE INVENTION
Sensitive loads such as computers, data processing equipment and medical equipment must be protected from sudden changes of the line voltage and/or frequency. Such sensitive or critical loads also include hospitals, clinics, life support system, military installations, land, air and sea borne traffic control installations, remote systems such as those controlled by the armed forces, weather monitoring systems, critical manufacturing processes, nuclear facilities, large banking facilities, computer installations, large building elevators, emergency lighting and other loads where loss of power can be threatening to human life or property. It is desirable to limit undesirable electrical power instabilities coming from the electric utility lines by using backup power sources.
British patent 1,309,858 discloses an uninterrupted power supply for ensuring that uninterrupted power is supplied to a load. This supply provides partial compensation to a voltage drop by connecting an auxiliary power supply to the load via a secondary winding of a transformer, the primary winding of which is connected to a choke located between the main power supply and the supply. The use of a transformer disadvantageously makes the system expensive.
Many of the current uninterrupted power supplies may accomplish the required protection using a rotating flywheel disadvantageously having large weight. Depending upon rotating flywheel mass requirements, the flywheel may be a separate structure or incorporated into an arrangement of the a motor, shaft, or rotor. For sensitive or critical loads where even a small change in frequency can cause problems, flywheel size requirement may become impractical. The flywheel large spinning mass also creates problems in startup and performance when acceleration or deceleration of the spinning mass is required.
EP 69568 discloses an uninterrupted power supply using a high frequency method wherein a high frequency alternating current (AC) power generator drives a small, high speed motor and flywheel both located in a sealed chamber. This approach is relatively expensive due to the use of an additional high frequency generator. Maintaining electric power frequency and phase within tolerances for sensitive or critical loads has also been a problem. Apparatus, which modifies frequency and other complex devices, have been used.
U.S. Pat. Nos. 4,827,152, 5,311,062 and 5,434,454 disclose uninterrupted power supplies having high pressurized hydraulic systems. These systems are unreliable since the high pressure piping included in these systems can burst. Furthermore, these systems do not provide the required frequency needed for such systems due to the need to accelerate the hydraulic motor at the outage instant.
There exists a need for a simpler and more effective power backup system which can substantially instantaneously respond to utility failures of the line power without the disadvantages of heavy flywheels or high pressurized hydraulics, and frequent maintenance. These and other disadvantages are solved or reduce using the present invention.
SUMMARY OF THE INVENTION
An object of the invention is to provide substantially instantaneous power to a sensitive or critical load, in case that the electric utility fails to provide adequate power to the load.
Another object of the invention is to provide a power supply having rotating flywheel in a compact design for providing a substantially instantaneous energy to a synchronous machine then providing the instantaneous power to the load during utility power failures.
Another object of the invention is to provide a drive motor powered by utility power functioning as for driving a rotating flywheel rotating at a speed greater than a synchronous machine which also functions as a generator providing instantaneously power to the load by transferring kinetic energy from the high speed flywheel to the generator during utility power failures.
Another object of the invention is to provide a magnetic clutch for controlling the amount of instantaneously kinetic energy transfer from the rotating flywheel to the synchronous machine.
Another object of the invention is to provide smooth phase sync transitions when transiting between utility power from the utility during normal operation, instantaneous power from the machine during a transitory period of utility failure and backup power from a backup supply during an extended period of utility failure.
The present invention is a power supply and method for providing a substantially instantaneous power to a sensitive load in case that the electric utility fails to provide energy to a load during a power outage. The power supply comprises a drive motor driving a high RPM rotating flywheel when the utility supplies operating utility power to the load and drives a synchronous machine functioning as a generator providing a substantially instantaneous power to the load during transitory utility power outages. The synchronous machine is coupled through a rotating shaft and a magnetic clutch to the flywheel. The magnetic clutch includes an induction bars coupled to the flywheel and field coils coupled to the shaft. A sensing means is used to detect when the utility power to the load is interrupted. During utility power outages, the magnetic clutch control changes the magnetic coupling of the induction bars and field coils so as to transfer instantaneous energy from the rotating flywheel to the shaft and to the synchronous machine now functioning as a generator supplying instantaneous power to the load during the transitory utility power outages.
The magnetic clutch is preferably driven by a split core transformer having its core split into two parts, one for the primary windings and the other for the secondary windings of the split core transformer. The magnetic clutch has induction bars coupled to the flywheel and has the field coil coupled to the secondary of the a split core transformer. The primary winding is coupled to a magnetic clutch control means. A magnetic clutch control signal is transmitted to the field coil of the magnetic clutch from the secondary winding of the split core transformer for controlling the amount of kinetic transferred energy magnetically coupled from the flywheel to the synchronous machine. The magnetic clutch control is regulated to control the amount of magnetic flux in the primary winding to control the clutch control signal from the secondary winding to generate magnetic flux in the magnetic clutch to variably control the magnetic coupling between the induction bars and the field coils for variably controlling the amount of energy transfer from the flywheel to the synchronous machine. During electric utility outage failure, the electromagnetic clutch maintains a constant speed on the common shaft driving the synchronous machine which then supplies the instantaneous power to the load. In the preferred embodiment, the stator of the magnetic clutch having the field coils is turning with the shaft of the synchronous machine, and the induction bars are coupled to the magnetic clutch housing and to the flywheel. The primary winding of the transformer is attached to a stationary frame of the power supply and the secondary winding of the transformer is attached to the rotating stator of the magnetic clutch. The preferred electromagnetic clutch control is controlled by a clutch control means and a control unit that variably changes the voltage across the primary winding of the transformer for coupling a control signal to the secondary winding and then to the field coils as a regulated variable control signal, which in turn, controls the amount of magnetic flux in the field coils of magnetic clutch
Ballato Josie
DeBeradinis Robert L.
Perfect Power Inc.
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