JP2004511199A - Rotary dynamic system power divider - Google Patents

Abstract

Provided is a highly reliable power distributor that switches power supply from a main power supply and a backup power supply to a target load.
A power distributor (PDU) stores energy in a device such as a flywheel, and when one power supply fails, an alternative power supply goes online while providing high-quality power supply to a load facility. Can be continued against. The three pole mechanical switch pair controls whether to use the main power supply or an alternative power supply. A standard motor generator is connected to the output of the mechanical switch, is used to transform the input power, and is used to utilize the stored energy while switching from the main power supply to the standby power supply.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to power switching systems, and more particularly to a reliable sub-cycle power switching / distribution system capable of supporting loads that are significantly affected by power interruptions.
[0002]
[Description of Background Art]
Buildings with large computer centers require large amounts of power. In the case of a core computer that needs to be provided with a power supply that needs to supply constant power continuously, it is more difficult to efficiently supply appropriate power to the building efficiently.
[0003]
Conventionally, the main computer has been supplied with power from a power circuit of an uninterruptible power supply (UPS). The UPS circuit monitors the power supply to the computer (that is, the circuit load), and switches to a standby power supply such as a battery to supply the power to the circuit load in the event of a power failure. From the computer's point of view, it is possible to continue operating normally without any loss of power.
[0004]
Critical data center computing devices are powered by two UPS systems and two UPS power distribution systems. Although such a system is redundant, it supplies power to the data processing device from the backup UPS system and the power transmission path, while maintaining the system or protecting it from failure or malfunction in one of the power transmission paths. Coping is possible.
[0005]
This system architecture is called a "system plus system" design. Referring to the electrical standpoint as close as possible to the critical load, by equipping the switching equipment, generally a static changeover switch (STS), the main power supply for the critical load, i. That is, it is possible to select an alternative power supply. Typically, this switch is located in a power distributor (PDU) that powers the computing device. A typical PDU includes at least one buck transformer and a distribution panel. The transformer converts the 480 volt power output of the UPS to the 208/120 volts required by the computing device. If a static switch is installed before the transformer, only one transformer is required, but if a static switch is installed after the transformer, two transformers are required. .
[0006]
As described above, a conventional important power distribution circuit uses a power switching circuit to switch power between a main power supply and a standby power supply. At the center of such a conventional power switching circuit is a static changeover switch (STS). With the STS, the system power supply is automatically switched from the main power supply to the backup power supply when the main power supply fails. Generally, STS circuits are designed with silicon controlled rectifier (SCR) power switching elements. In other words, the semiconductor device is used to quickly switch the power supply destination from the main power supply to the standby power supply.
In general, STS-based circuits are highly reliable in that they continue to power critical applications in the event of a main power failure, but are still vulnerable in that the STS circuit itself may fail. It is.
[0007]
A typical STS has a mean time between failures (MTBF) of 400,000 hours. Although it may seem like a long time, as the number of STSs installed at a site increases, the overall reliability of the site decreases proportionally. For example, at a site equipped with 20 STSs, the MTBF of the entire system is about 20,000 hours (slightly less than 2.5 years). MTBF in large data centers equipped with 50 or more devices is less than one year. For modern data centers that are designed to operate 24 hours a day, 7 days a year, this failure rate is very severe.
[0008]
Accordingly, there is a need in the art to provide a highly reliable switching circuit that switches power supply from a main power supply and a backup power supply to a target load.
[0009]
[Means for Solving the Problems]
The systems and methods are consistent with the principles of the present invention that address the needs raised above by providing an improved power divider that powers critical devices that require uninterrupted power. .
[0010]
According to one aspect of the present invention, there is provided a power distributor including a plurality of elements. Its elements include a synchronous motor generator, first and second mechanical switches, and a primary and secondary input power supply. The first mechanical switch is opened when a failure is detected in the primary power supply. A transfer logic circuit configured to reverse the switching states of the first and second mechanical switches so as to close the second mechanical switch.
[0011]
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, together with description, objects, advantages, and principles of the invention. Identical or similar parts in the several figures are indicated by the same reference numerals.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the following detailed description, reference is made to the accompanying drawings that illustrate embodiments of the invention. Other embodiments are possible, and modifications can be made to the embodiments without departing from the spirit and scope of the invention. Accordingly, the following detailed description does not limit the invention. Rather, the scope of the present invention is defined by the appended claims.
[0013]
As described herein, a power distributor (PDU) provides power to a target load, such as a critical computer system. The PDU has a main power supply and a backup power supply, and can switch to the backup power supply when a problem occurs in the regular power supply. The power is sent to the target load so that the target load can operate continuously as if there was no power interruption. PDUs can use rotary technology in the form of a synchronous motor generator set that includes a flywheel to provide a "transit" of power switching.
[0014]
FIG. 1 is a single-line wiring diagram showing components of a power distributor (PDU) according to the present invention.
[0015]
During normal operation, the PDU 100 receives electric power input from two individual power supplies named a normal power supply “A” 101 and an alternative power supply “B” 102. This input power is sent from one of the two 400 amp circuit breakers 105,106. Typically, the power from power supplies 101, 102 is 480 volts.
[0016]
Contactors 111, 112 are standard three-pole mechanical switches operated by electrical signals under the control of transfer logic 110. The line side of the contactors 111 and 112 is connected to a power supply, and the load side is connected to a motor generator 115. When the service power supply 101 fails, the transfer logic 110 controls the contactors 111 and 112 to switch to the alternative power supply 102.
[0017]
The transfer logic 110 performs control based on input information from the detection device. In particular, the current transformer (CT) 140 and the instrument transformer (PT) 141 are located at the output of the generator 121 in front of the contactors 111 and 112, and (a) the regular input power supply 101 and the alternative input power supply 102 (B) to identify abnormalities such as insufficient voltage and overcurrent occurring at the ends of the input power supplies 101 and 102 and at the output of the generator 121. Synchronous motor generator 115 is shown by peripheral components 116-122 within the dashed line in FIG.
[0018]
Components 116-122 include contactors 116, 117, start / execute logic 118, pony start motor 119, synchronous motor 120, generator 121, and flywheel 122.
[0019]
Motor generator 115 performs two functions of PDU 100. That is, (1) the input power of 480 volts is transformed into the power of 208/120 volts normally required by the load device, and (2) the connection is made when the normal power supply 101 is switched to the alternative power supply 102 (or vice versa). Is easy to do.
[0020]
Occasionally it may be necessary to take synchronous motor generator 115 offline for repair or maintenance. In that situation, a bypass control circuit 126 that activates the circuit breakers 127 and 128 and passes power from either the motor generator 115 or the transformer 125 is used to reduce the power path from the active power supply to the buck. Determined by transformer 125. Like the transformer 125, the synchronous motor generator 115 converts the input power to 208/120 volts of power utilized at the output. However, at the time of a power failure, the transformer 125 cannot continue stable power supply.
[0021]
Finally, power from the motor generator 115 or the transformer 125 is sent through the circuit breaker 130 to the circuit distribution panel to which the load device is connected. The circuit distribution panel may be, for example, a 225 amp, 3-pole, 4-wire 42-circuit distribution panel.
[0022]
(Normal operation)
Next, the normal operation of the PDU 100 will be described. In normal operation, power is supplied from the commercial power supply 101 to the contactor switch 111 through the circuit breaker 105. When the contactor switch 111 is closed, power can be sent to the synchronous motor generator 115. Conversely, when the contactor 112 opens, power supply from the alternative power supply 102 to the motor generator 115 is cut off. At this time, when the bypass transformer 125 is not used, it is preferable that the circuit breakers 107 and 108 are set to open.
[0023]
In the synchronous motor generator 115, the contactor 116 is opened, the contactor 117 is closed, and the input power is supplied to the motor 120 to rotate the generator 121. When connected as shown in FIG. 1, motor 120 and generator 121 transform 480 volts input power to 208/120 volts output power, which powers circuit breakers 128 and circuit breakers 130. Through the output circuit distribution panel and the target load. Since the motor 120 and the generator 121 are mechanically connected, the input of the power to the motor and the output of the power from the generator to the load of the main computer equipment are completely electrically separated.
[0024]
Further, the motor 120 supplies power to the flywheel 122. The flywheel 122 supplies backup power to the generator for a short time when the input power to the generator 121 is interrupted. Flywheels are well known in the art. Generally, flywheels store energy as mechanical kinetic energy due to the rotation of the flywheel. When the power to the generator 121 is interrupted, the generator 121 converts the kinetic energy of the rotating flywheel into electrical energy until a stable power supply is obtained online.
[0025]
(Operation during power transmission)
The transfer logic circuit 110 uses the current transformer 140 and the instrument transformer 141 to monitor whether or not the input power supply is defective. If a malfunction such as a power shutdown or a sudden decrease is detected, the transfer logic 110 starts switching to the alternative power supply 102 by opening the contactor switch 111 and closing the contactor switch 112 at the same time. .
[0026]
The three-pole mechanical contactor is characterized in that it takes a long time to close the contactor, so that an electric circuit is formed, and the circuit opens the contactor to interrupt the electric circuit. Therefore, when an electrical signal for opening the contactor 111 and closing the contactor 112 is output from the transfer logic 110, the contactor 111 opens before the contactor 112, so that the power sources 101 and 102 are electrically connected. Are reliably separated.
[0027]
The contactors 111, 112 are available as 400 amp triode contactors. This contactor can be purchased from several companies, such as General Electric. Contactor "pickup" (PU) time (i.e., elapsed time to close) is 110-115 milliseconds, and "dropout" (DO) time (i.e., open time) is 70-80 milliseconds. Seconds. PU is obtained by applying a voltage to the working coil and measuring from the end of operation of the armature of the contactor, and DO is measuring by turning off the voltage of the operating coil to the end of operation of the armature of the contactor. Obtained by When the transfer logic circuit 110 turns off the voltage of the coil of one contactor while applying voltage to the coil of the other contactor, the power supply is turned off because at least 30 milliseconds elapse between the opening and closing of the contactor. Separated reliably.
[0028]
The transfer logic 110 is configured not to be sensitive to undervoltage or overcurrent conditions downstream of the system, but only to the undervoltage, ie, single-phase condition, downstream of the contactor switches 111, 112.
[0029]
A power interruption caused by a delay before switching the alternative power source 102 to the motor generator 115 may cause the synchronous motor 120 to lose synchronization with the input power. Pony motor 119 is used to resynchronize with motor 120. Start / execute logic 118 closes contactor 116 when motor 120 loses synchronization and power is supplied to pony motor 119, and then when motor 120 detects resynchronization with the input power. At this time, the start / execute logic 118 opens the contactor 116 and supplies power to the pony motor 119.
[0030]
The flywheel 122 supplies energy to the generator 121 while the motor 120 is resynchronizing while the alternative power supply is provided online, and the generator 121 supplies available power to the target load. You can continue. From the viewpoint of the target load, power is not interrupted even for a moment.
[0031]
During the transmission process described above, the frequency of generator 121, which typically produces 60 Hertz of power, can attenuate to about 59.5 Hertz. This decay lasts for about 6 Hertz (1/10 second) until the alternate power is applied online and the motor 120 resynchronizes. The frequency is returned to normal within a further 15 seconds and never falls below the minimum input requirements of the load (eg, a computing device).
[0032]
Unlike power dividers based on static changeover switches, where power is completely interrupted for 4-8 milliseconds during operation, PDU 100 does not interrupt power. In the event of a power outage, the generator 121 will continue to generate power, usually with a voltage increase or decrease of only about 1 volt.
[0033]
(Operation during maintenance)
For maintenance or inspection, the motor generator 115 may be manually disconnected from the electrical circuit of FIG. In particular, when the circuit breakers 105, 106, 128 are opened, the motor generator 115 is electrically disconnected from the system. Before disconnecting the motor generator 115, the power supply is routed to the transformer 125 via the circuit breakers 107 or 108. Transformer 125 may be a delta-wye buck transformer that transforms 480 volts input power to 208/120 volts output power. The bypass control circuit 126 controls switching from the motor generator 115 to the transformer 125.
[0034]
In a delta star transformer, a phase shift (eg, a 30 degree phase shift) is inserted between the input voltage and the output voltage. If the transformer 125 is a delta-star type transformer, it is necessary to insert a phase shift into the output of the motor generator 115 to match the output of the transformer.
[0035]
(Physical mounting form)
FIG. 2 is a diagram showing a physical layout of the PDU 100. As shown, the proposed PDU unit is 82 inches high and 210 inches long. The depth of the PDU may be 38 inches. These dimensions are exemplary only, and those skilled in the art will appreciate that other equivalent PDUs can be constructed with other dimensions. Usually, the PDU 100 is installed in a building near the target load.
[0036]
Synchronous motor generators, such as synchronous motor generator 115, are well known in the art. One manufacturer of such motor generators is Kato Manufacturing of Mankato, Minnesota. If a phase shift is needed to match the phase shift inserted by the transformer 125, the Kato motor generator may be modified with non-standard windings to insert the phase shift.
[0037]
Above, the power distribution module without a power outage was described. PDUs use an internal backup energy source, such as a flywheel, to easily and reliably switch from a main power supply to a standby power supply during a power outage. Further, the PDU can realize a highly reliable operation without relying on a semiconductor static changeover switch, and can be constituted by off-the-shelf components that can be easily purchased.
[0038]
Reverting to the use of mechanical switching devices instead of static switching devices may seem backward, but the reliability of mechanical devices is higher than the reliability of their electronic equivalents. During operation of the mechanical switch, only a "transit" of power is required. It is supplied by a synchronous motor generator inserted in the power circuit between the switching device and the critical load equipment. As the voltage is reduced, the motor runs at 480 volts when the generator produces 208/120 volts of power. It replaces the standard PDU transformer.
[0039]
While figures and descriptions have been provided for the preferred embodiments of the invention described above, they are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Modifications and changes may be made in harmony with the above teachings, or modifications and changes may be made based on embodiments of the invention. For example, although described as converting 480 volts of power to 120 volts of power, those skilled in the art will appreciate that the predetermined level can be easily changed based on the power requirements of a particular site. Can be. It is also clear that the number of power supplies is not limited to two. More than two power supplies can be used within the scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.
[Brief description of the drawings]
FIG.
FIG. 1 is a circuit diagram showing components of a power distributor according to the present invention.
FIG. 2
FIG. 2 is a diagram showing a physical layout of the power distributor.

Claims (11)

A synchronous motor generator including a power input wiring for receiving power and a power output wiring for transmitting power, wherein the energy received from the power input wiring is stored, and a wiring failure of the received input power has occurred. When sending the stored energy to the power output wiring, the synchronous motor generator,
A first mechanical switch connected to a service power supply and the power input wiring of the synchronous motor generator;
A second mechanical switch connected to an alternative power supply and to the power input wiring of the synchronous motor generator;
The first and second mechanical power supplies are monitored so as to open the first mechanical switch and close the second mechanical switch when the service power supply and the alternative power supply are monitored and a failure of the service power supply is detected. A power divider comprising a transfer logic circuit configured to reverse a switching state of a switch. A power distribution panel connected to the output wiring of the synchronous motor generator,
2. The step-down transformer according to claim 1, further comprising a step-down transformer, wherein one input of a step-down transformer is connected to the service power supply and the alternative power supply via a circuit breaker, and the power distribution panel is connected to an output of the step-down transformer. 3. Power distributor. 3. The power distributor of claim 2, further comprising a bypass control circuit configured to route power supply to one of the synchronous motor generator and the step-down transformer. The power distributor of claim 1, wherein the power received by the synchronous motor generator is 480 volts, and the synchronous motor generator transforms the received power to 120 volts on output wiring of the synchronous motor generator. The power distributor of claim 1, wherein energy stored by the synchronous motor generator is stored as kinetic energy at a flywheel. The transfer logic circuit simultaneously sends a signal to the first and second mechanical switches when reversing the switching states of the first and second mechanical switches, 2. The power distributor of claim 1, wherein opening the first mechanical switch before closing the switch ensures that the utility power and the alternative power source are separated. A first power source;
A second power source;
A first three-pole mechanical switch connected to the first power supply on a line side;
A second three-pole mechanical switch to which the second power supply is connected on the line side;
A synchronous motor generator system including a motor, a generator, and a flywheel, wherein an input of the synchronous motor generator is connected to a load side of the first and second mechanical switches, A synchronous motor generator system for receiving electric power from the first and second power supplies via the second mechanical switch and outputting a transformed version of the received electric power,
Configured to monitor the first power supply and connected to a transformer / current transformer located before the first and second mechanical switches and located at the output of the motor generator. Transfer logic, the transfer logic including, when the transfer logic detects a failure of the first power supply, simultaneously outputting a command for reversing a switching state of the first and second mechanical switches. ,
By simultaneously outputting the command, a temporary interruption occurs in the power received by the synchronous motor generator, and the generator of the synchronous motor generator generates power from energy stored in the flywheel. A power distributor that compensates for the temporary interruption of the power and continuously outputs the power supplied from the synchronous motor generator as usable power. A power distribution panel connected to the output of the synchronous motor generator,
8. The power of claim 7, further comprising a step-down transformer having one input connected to the first and second power supplies via a circuit breaker and having an output connected to the distribution panel. Distributor. 9. The power distributor of claim 8, further comprising a bypass control circuit configured to route power from the service power source A or the alternative power source B to the step-down transformer and the synchronous motor generator. . 9. The power distributor of claim 7, wherein the power received by the synchronous motor generator is 480 volts, and the synchronous motor generator transforms the received power to an output power of 120 volts. When reversing the switching state of the first and second mechanical switches, the first mechanical switch opens before the second mechanical switch closes, so that the first power supply and the second 8. The power divider of claim 7, wherein the power supplies are reliably separated.

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