JP2011229260A - Uninterruptible power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply system capable of attaining high efficiency and a long life cooling fan.SOLUTION: The uninterruptible power supply comprises a main inverter 12 that provides AC power to a load 52 and also a sub-inverter 24 that provides AC power to a cooling fan 26, which controls a rotational speed of the cooling fan 26 to prevent a temperature T in a housing 1 from exceeding a predetermined temperature T0, when a load current I is larger than a threshold current Ith. When the load current I is smaller than the threshold current Ith, the cooling fan 26 is driven intermittently. And if the sub-inverter 22 is failed, the AC power will be provided to the cooling fan 26 from an AC power supply. Therefore, the efficiency of the uninterruptible power supply system becomes higher and the life of the cooling fan 26 becomes longer than that of the conventional art in which the cooling fan 26 is driven always at a rated speed.

Description

  The present invention relates to an uninterruptible power supply, and more particularly to an uninterruptible power supply having a cooling fan.

  Conventionally, an uninterruptible power supply has been widely used as a power supply that stably supplies AC power to an important load such as a computer system. An uninterruptible power supply is generally generated by a converter that converts commercial AC power into DC power, an inverter that converts DC power generated by the converter or DC power from a battery to AC power, and supplies the load to a load. And a cooling fan that is driven by AC power and cools the inside of the housing in which the main body of the uninterruptible power supply is housed (see, for example, Non-Patent Document 1).

"150kVA System Drawings" of 9700 series on the Internet homepage of MITSUBISHI ELECTRIC POWER PRODUCTS, INC

  However, in the conventional uninterruptible power supply, the AC power generated by the inverter is supplied to both the load and the cooling fan, and the cooling fan is always rotated at the rated speed. There was a problem that the life of the fan was short.

  Therefore, a main object of the present invention is to provide an uninterruptible power supply device with high efficiency and a long cooling fan life.

  An uninterruptible power supply according to the present invention is an uninterruptible power supply provided in a housing, and converts a first AC power from an AC power source into DC power, and DC power generated by the converter or A main inverter that converts DC power from the power storage device into second AC power of constant voltage at a constant frequency and supplies the second AC power to the load, and DC power generated by the converter or DC power from the power storage device at a desired frequency The sub-inverter for converting to the third AC power having a desired voltage in step S3, and if the sub-inverter has not failed, the third AC power is supplied to the power supply node, and if the sub-inverter has failed, the first AC power is supplied. Switching circuit that supplies power to the power supply node, a cooling fan that is driven by AC power supplied through the power supply node and cools the inside of the housing, and detects the temperature inside the housing When the load current detected by the current sensor and the load sensor detected by the current sensor are larger than the predetermined current, the temperature detected by the temperature sensor should not exceed the predetermined temperature. If the load current is smaller than the predetermined current by controlling the sub inverter and controlling the rotation speed of the cooling fan, the sub fan is controlled intermittently regardless of the temperature detected by the temperature sensor. And a control circuit to be driven.

  Preferably, the switching circuit supplies the third AC power to the power supply node when both the main inverter and the sub inverter have not failed, and the first AC power when both the main inverter and the sub inverter have failed. Is supplied to the power supply node, and when only the sub inverter out of the main inverter and the sub inverter fails, the second AC power is supplied to the power supply node.

  Preferably, the control circuit gradually increases the rotation speed of the cooling fan from a lower limit value to an upper limit value over a predetermined time when the rotation speed of the cooling fan is increased when the cooling fan is driven intermittently. Increase to.

  Further preferably, a lower limit limiting circuit for limiting the lower limit of the rotation speed of the cooling fan to a predetermined rotation speed larger than 0 when the load current is larger than the predetermined current is further provided.

  In the uninterruptible power supply according to the present invention, in addition to the main inverter that drives the load, a sub inverter that drives the cooling fan is provided, and when the load current is larger than a predetermined current, the temperature detected by the temperature sensor is Control the sub inverter to control the rotation speed of the cooling fan so as not to exceed the predetermined temperature. If the load current is smaller than the predetermined current, control the sub inverter to intermittently cool the cooling fan. Drive. Therefore, the efficiency of the uninterruptible power supply becomes higher and the life of the cooling fan becomes longer than in the conventional case where the cooling fan is always driven at the rated rotational speed. Further, when the sub inverter fails, the cooling fan is driven by the AC power supply, so that reliability can be ensured.

It is a circuit block diagram which shows the structure of the uninterruptible power supply by one embodiment of this invention. 2 is a time chart showing waveforms of control signals generated by the signal generation circuit shown in FIG. 1. It is a circuit block diagram which shows the example of a change of embodiment. It is a circuit block diagram which shows the other example of a change of embodiment. It is a circuit block diagram which shows the other example of a change of embodiment.

  As shown in FIG. 1, the uninterruptible power supply according to the present embodiment includes a housing 1 that houses a main body, a bypass input terminal T1, an AC input terminal T2, a battery terminal T3, And an output terminal T4. Each of input terminals T1, T2 receives AC power from an AC power supply. The AC power source is a commercial AC power source, a private generator, or the like. AC power is three-phase or single-phase. The battery terminal T3 is connected to the positive electrode 50a of the battery 50. The battery 50 is housed in a housing 51 different from the housing 1. A load 52 is connected to the output terminal T4.

  Further, a converter operation / stop command unit 2 and an inverter operation / stop command unit 3 are provided on the outer wall of the housing 1, and the main control circuit 4, switches 5, 10, 15, 16, Fuses 6 and 9, a reactor 7, a converter 8, capacitors 11 and 14, a main inverter 12, a transformer 13, and an STS (Static transfer Switch) 17 are provided. The switch 5, the fuse 6, the reactor 7, the converter 8, the main inverter 12, the transformer 13, and the switch 15 are connected in series between the AC input terminal T2 and the output terminal T4.

  Fuse 9 and switch 10 are connected in series between output node 8a of converter 8 and battery terminal T3. Capacitor 11 is connected between output node 8a of converter 8 and a reference voltage line. The capacitor 14 is connected between the output terminal 13a of the transformer 13 and a reference voltage line. The switch 16 and the STS 17 are connected in parallel between the bypass input terminal T1 and the output terminal T4.

  Each of converter operation / stop command unit 2 and inverter operation / stop command unit 3 is operated by a user of the uninterruptible power supply. When converter 8 is operated, a switch (not shown) of converter operation / stop command unit 2 is turned on, and signal φ2 is set to “H” level. When stopping the operation of converter 8, a switch (not shown) of converter operation / stop command unit 2 is turned off, and signal φ2 is set to the “L” level.

  When operating the main inverter 12, a switch (not shown) of the inverter operation / stop command unit 3 is turned on, and the signal φ3 is set to the “H” level. When stopping the operation of main inverter 12, a switch (not shown) of inverter operation / stop command unit 3 is turned off, and signal φ3 is set to the “L” level. The main control circuit 4 controls the entire uninterruptible power supply according to the signals φ2 and φ3 from the command units 2 and 3.

  Switch 5 is turned on when output signal φ2 of converter operation / stop command unit 2 is at “H” level, and is turned off when signal φ2 is at “L” level. The fuse 6 is blown when an excessive current flows from the AC input terminal T2 to the converter 8 to protect the converter 8 and the like. Reactor 7 blocks the carrier frequency signal generated in converter 8 and prevents the carrier frequency signal from adversely affecting the AC power supply side.

  Converter 8 is controlled by main control circuit 4 when output signal φ2 of converter operation / stop command unit 2 is at “H” level, and AC power supplied from AC power supply via AC input terminal T2 is converted to DC power. Convert. When signal φ2 is at “L” level, operation of converter 5 is stopped.

  The fuse 9 is blown when an excessive current flows between the node between the converter 8 and the main inverter 12 and the battery 50, and protects the converter 8, the main inverter 12, the battery 50, and the like. The switch 10 is controlled by the main control circuit 4 and is turned on when the battery 50 is charged and discharged, and turned off when the battery 50 is replaced. Capacitor 11 smoothes the DC voltage generated by converter 8.

  The main inverter 12 is controlled by the main control circuit 4 when the output signal φ3 of the inverter operation / stop command unit 3 is at “H” level, and is generated by the converter 8 or the DC power supplied from the battery 50. To AC power. The frequency and phase of the AC power generated by the main inverter 12 are the same as the frequency and phase of the AC power supplied from the AC power source. Further, the frequency and voltage of the AC power generated by the main inverter 12 are constant. When signal φ3 is at “L” level, operation of main inverter 12 is stopped.

  The transformer 13 boosts the output voltage of the main inverter 12 and supplies it to the load 52. Further, the transformer 13 and the capacitor 14 constitute an output filter, cut off the carrier frequency signal generated by the main inverter 12, and prevent the carrier frequency signal from adversely affecting the load 52.

  The switch 15 is controlled by the main control circuit 4 and is turned on in the inverter power supply mode in which the AC power generated by the main inverter 12 is supplied to the load 52. The switch 16 is controlled by the main control circuit 4 and is turned on in the bypass power supply mode in which the AC power supplied from the AC power supply via the bypass input terminal T1 is supplied to the load 52. The STS 17 is turned on when the main inverter 12 fails in the inverter power supply mode, and instantaneously applies AC power supplied from the AC power source via the bypass input terminal T1 to the load 52.

  Further, a setter 20, a signal generation circuit 21, a sub control circuit 22, switches 23 and 25, a sub inverter 24, a cooling fan 26, a current sensor 27, and a temperature sensor 28 are further provided in the housing 1. Yes. The sub inverter 24 is controlled by the sub control circuit 22 and converts the AC power generated by the converter 8 or the DC power supplied from the battery 50 into AC power having a desired voltage at a desired frequency.

  The switch 23 is connected between the AC input terminal T2 and the power supply node 26a of the cooling fan 26. The switch 25 is connected between the output node of the sub inverter 24 and the power supply node 26 a of the cooling fan 26. The sub control circuit 22 determines whether or not the sub inverter 24 has failed. When the sub inverter 24 has not failed, the sub control circuit 22 turns off the switch 23 and turns on the switch 25. The switch 25 is turned off and the switch 23 is turned on. The cooling fan 26 is driven by AC power supplied via the switches 23 and 25, discharges air in the housing 1, introduces outside air into the housing 1, and cools the inside of the housing 1.

  When the output frequency and voltage of the sub inverter 24 are increased, the rotational speed of the cooling fan 26 is also increased, and the amount of air discharged from the housing 1 and the amount of outside air introduced into the housing 1 are increased. When the frequency and voltage of the output of the sub inverter 24 are lowered, the number of rotations of the cooling fan 26 is also lowered, and the amount of air discharged into the housing 1 and the amount of outside air introduced into the housing 1 are reduced. Therefore, the rotation frequency of the cooling fan 26 can be controlled by controlling the frequency and voltage of the output of the sub inverter 24, and the temperature in the housing 1 can be adjusted. The output frequency / voltage ratio of the sub inverter 24 is controlled to be constant.

  The current sensor 27 is provided between the switches 15 and 16 and the output terminal T4, detects the load current, and gives a signal indicating the detected value to the signal generation circuit 21. The temperature sensor 28 detects the temperature in the housing 1 and gives a signal indicating the detected value to the sub-control circuit 22. The setting device 20 is operated by a user of the uninterruptible power supply. When the set value R1 is set by the user of the uninterruptible power supply, the setter 20 gives the set value R1 to the signal generation circuit 21.

  When the load current I detected by the current sensor 27 is smaller than the threshold current Ith that is sufficiently smaller than the rated current, the signal generation circuit 21 controls the control signal φR having a predetermined frequency for intermittently operating the cooling fan 26. Is generated. When the set value R1 is given from the setter 20, the level of the control signal φR is from 0 to the set value R1 in the first half period of each cycle (for example, t0 to t1) as shown in FIG. It gradually rises and becomes 0 in the second half period (for example, t10 to t2). Further, when the set value R1 is not given from the setter 20, the level of the control signal φR becomes a predetermined value R2 (> R1) in the first half period of each cycle as shown in FIG. It becomes 0 in the second half period.

  When the load current I is smaller than the threshold current Ith, the sub control circuit 22 controls the sub inverter 24 according to the control signal φR to drive the cooling fan 26 intermittently. In this case, the rotational speed of the cooling fan 26 changes according to the level change of the control signal φR shown in FIGS. That is, when the set value R1 is given from the setting device 20, the rotation speed of the cooling fan 26 is a rotation corresponding to the set value R1 from 0 in the first half period of each cycle as shown in FIG. It gradually increases to a number and becomes 0 in the second half period. Further, when the set value is not given from the setting device 20, the rotation speed of the cooling fan 26 corresponds to a predetermined value R2 (> R1) in the first half period of each cycle as shown in FIG. It becomes the rotation speed and becomes 0 in the second half period.

  Further, when the load current I is larger than the threshold current Ith, the sub-control circuit 22 determines that the temperature T in the housing 1 does not exceed a predetermined temperature T0 based on the detected temperature T of the temperature sensor 28. Thus, the sub inverter 24 is controlled to control the rotation speed of the cooling fan 26.

  Next, the operation of this uninterruptible power supply will be described. When the uninterruptible power supply is started, first, switches 5 and 10 are turned on, converter 8 is operated, and capacitor 11 and battery 50 are charged. When charging of the capacitor 11 and the battery 50 is completed, the main inverter 12 is operated. When the output voltage of the main inverter 12 is stabilized, the switch 15 is turned on, and AC power is supplied to the load 52 in the inverter power supply mode. When AC power is normally supplied from the AC power supply, the AC power is converted into DC power by the converter 8. The DC power generated by the converter 8 is supplied to the battery 50 and the main inverter 12. The main inverter 12 converts the DC power supplied from the converter 8 into DC power having a constant frequency and a constant voltage, and supplies the DC power to the load 52.

  At the time of a power failure in which the supply of AC power from the AC power supply is stopped, the switch 5 is turned off and the operation of the converter 8 is stopped, and the DC power of the battery 50 is supplied to the main inverter 12. The main inverter 12 converts the DC power supplied from the battery 50 into AC power having a constant frequency and a constant voltage, and supplies the AC power to the load 52. Thus, even when a power failure occurs, the operation of the load 52 can be continued as long as DC power is stored in the battery 50. When the power failure is recovered in a short time, the switch 5 is turned on again to operate the converter 8 and return to the inverter power supply mode.

  Further, when the main inverter 12 fails in the inverter power supply mode, the STS 17 is turned on, and the AC power supplied from the AC power supply via the bypass input terminal T1 is instantaneously applied to the load 52. Next, the switch 16 is turned on, the switch 15 and the STS 17 are turned off, and AC power is supplied to the load 52 in the bypass power supply mode.

  When the uninterruptible power supply is operated and current is supplied to the load 52, heat is generated in the main inverter 12 and the temperature T in the housing 1 is increased. The sub control circuit 22 controls the sub inverter 24 to control the rotation speed of the cooling fan 26 so that the temperature T detected by the temperature sensor 28 does not exceed the predetermined temperature T0. As the load capacity increases, the output of the main inverter 12 increases, the amount of heat generated by the main inverter 12 increases, and the temperature T in the housing 1 increases. When the temperature T in the housing 1 increases, the rotational speed of the cooling fan 26 increases. When the temperature in the housing 1 decreases below the predetermined temperature T0, the rotational speed of the cooling fan 26 decreases. In this way, the temperature T in the housing 1 is prevented from exceeding the predetermined temperature T0.

  Further, when the switch 15 is not turned on at the time of startup or when the load capacity is sufficiently small, the temperature rise in the housing 1 is small. Therefore, the signal generation circuit 21 and the sub control circuit 22 operate the cooling fan 23 intermittently when the load current I is smaller than the threshold current Ith. When the sub inverter 24 fails, the sub control circuit 22 turns on the switch 23 and turns off the switch 25. The cooling fan 26 is driven by AC power from an AC power source and cools the inside of the housing 1.

  In this embodiment, in addition to the main inverter 12 that drives the load 52, a sub inverter 24 that drives the cooling fan 26 is provided, so that the temperature T in the housing 1 does not exceed a predetermined temperature T0. To control the rotation speed of the cooling fan 26. When the load current I is smaller than the threshold current Ith, the cooling fan 26 is operated intermittently. The power consumption of the cooling fan 26 is proportional to the cube of the rotational speed, and the life of the cooling fan 26 is determined by the product of the rotational speed and time. Therefore, the power consumption of the cooling fan 26 is reduced, the efficiency of the uninterruptible power supply device is increased, and the life of the cooling fan 26 is extended as compared with the conventional case where the cooling fan 26 is always driven at the rated rotational speed.

  That is, when the uninterruptible power supply is activated, when only the converter 8 is operated and the operation of the main inverter 12 is stopped, the output of the uninterruptible power supply is zero. In this case, since the heat generation amount in the housing 1 is small, the cooling fan 26 is operated intermittently. When the capacity of the load 52 is smaller than the rated value, the cooling fan 26 is rotationally driven at a rotational speed smaller than the rated rotational speed. Accordingly, even in these cases, the cooling fan 26 is always driven to rotate at the rated rotational speed, and the power consumption of the cooling fan 26 can be reduced in the present embodiment as compared with the prior art.

  Further, when the sub inverter 24 fails, the cooling fan 26 is driven by AC power from an AC power source. Therefore, even if the sub inverter 24 fails, the inside of the housing 1 can be cooled, and reliability can be ensured.

  FIG. 3 is a circuit block diagram showing a modified example of this embodiment, and is a diagram to be compared with FIG. Referring to FIG. 3, this modified example is different from the uninterruptible power supply of FIG. 1 in that a lower limit limiting circuit 29 is added. The lower limit circuit 29 is operated by a user of the uninterruptible power supply. The lower limit circuit 29 gives the lower limit value RL to the signal generation circuit 21 when the lower limit value RL of the rotation speed of the cooling fan 26 is set by the user of the uninterruptible power supply.

  When the load current I is smaller than the threshold current Ith, the signal generating circuit 21 generates a control signal φR for intermittently operating the cooling fan 26, and the load current I is larger than the threshold current Ith. Generates a signal indicating the lower limit value RL. When the load current I is larger than the threshold current Ith, the sub control circuit 22 keeps the temperature T in the housing 1 from exceeding a predetermined temperature T0 based on the temperature T detected by the temperature sensor 28. Then, the sub inverter 24 is controlled to control the rotation speed of the cooling fan 26.

  Further, when the load current I is larger than the threshold current Ith, the sub control circuit 22 limits the lower limit of the output frequency of the sub inverter 24 to a predetermined frequency higher than 0, and the rotational speed of the cooling fan 26. Is limited to a predetermined rotational speed RL greater than zero. In this modified example, since the rotation speed of the cooling fan 26 is set to be larger than the predetermined lower limit value RL, even if the temperature sensor 28 fails, it is possible to prevent the temperature in the housing 1 from rising abnormally. . Therefore, it is possible to prevent the uninterruptible power supply device from being broken due to a temperature rise, and to improve the reliability.

  FIG. 4 is a circuit block diagram showing another modification of this embodiment, and is a diagram to be compared with FIG. Referring to FIG. 4, this modified example is different from the uninterruptible power supply of FIG. 1 in that a switch 30 is added. The switch 30 is connected between the output terminal 13 a of the transformer 13 and the power supply node 26 a of the cooling fan 26.

  The sub control circuit 22 determines whether or not each of the main inverter 12 and the sub inverter 24 has failed. When both the main inverter 12 and the sub inverter 24 have not failed, the sub control circuit 22 turns on the switch 25 and switches The AC power generated by the sub inverter 24 is supplied to the cooling fan 26.

  Further, when only the sub inverter 24 of the main inverter 12 and the sub inverter 24 fails, the sub control circuit 22 turns off the switches 23 and 25 and turns on the switch 30 to generate the AC generated by the main inverter 12. Electric power is supplied to the cooling fan 26. In addition, when both the main inverter 12 and the sub inverter 24 fail, the sub control circuit 22 turns off the switches 25 and 30 and turns on the switch 23 to supply AC power from the AC power source to the cooling fan 26. .

  In this modified example, when the sub inverter 24 breaks down, the cooling fan 26 is driven by the output of the main inverter 12, so that the temperature in the housing 1 is prevented from rising above. Therefore, it is possible to prevent the uninterruptible power supply device from being broken due to a temperature rise, and to improve the reliability.

  Further, as shown in FIG. 5, the modification example of FIG. 3 and the modification example of FIG. 4 may be combined, and a lower limit circuit 29 and a switch 30 may be added to the embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,51 Case, T1 bypass input terminal, T2 AC input terminal, T3 battery terminal, T4 output terminal, 2 converter operation / stop command section, 3 inverter operation / stop command section, 4 main control circuit, 5, 10, 15 16, 23, 25, 30 Switch, 6, 9 Fuse, 7 Reactor, 8 Converter, 11, 14 Capacitor, 12 Main inverter, 13 Transformer, 17 STS, 20 Setter, 21 Signal generation circuit, 22 Sub control circuit, 24 Sub inverter, 26 Cooling fan, 27 Current sensor, 28 Temperature sensor, 29 Lower limit circuit, 50 Battery, 52 Load.

Claims (4)

An uninterruptible power supply device provided in the housing,
A converter that converts first AC power from an AC power source into DC power;
A main inverter that converts the DC power generated by the converter or the DC power from the power storage device into a second AC power having a constant frequency and a constant voltage, and supplying the second AC power to the load;
A sub inverter that converts the DC power generated by the converter or the DC power from the power storage device into a third AC power having a desired voltage at a desired frequency;
A switching circuit for supplying the third AC power to the power supply node when the sub inverter is not faulty, and supplying the first AC power to the power supply node when the sub inverter is faulty;
A cooling fan that is driven by AC power supplied via the power supply node and cools the inside of the housing;
A temperature sensor for detecting the temperature in the housing;
A current sensor for detecting the load current;
When the load current detected by the current sensor is greater than a predetermined current, the cooling fan is controlled by controlling the sub inverter so that the temperature detected by the temperature sensor does not exceed a predetermined temperature. And controlling the sub inverter to drive the cooling fan intermittently regardless of the temperature detected by the temperature sensor when the load current is smaller than the predetermined current. An uninterruptible power supply comprising a circuit.   The switching circuit supplies the third AC power to the power supply node when both of the main inverter and the sub inverter are not faulty, and when both of the main inverter and the sub inverter are faulty, the switching circuit supplies the third AC power. The AC power of 1 is supplied to the power supply node, and when only the sub inverter of the main inverter and the sub inverter fails, the second AC power is supplied to the power supply node. Uninterruptible power supply.   When the rotation speed of the cooling fan is increased when the cooling fan is intermittently driven, the control circuit gradually increases the rotation speed of the cooling fan from a lower limit value to an upper limit value over a predetermined time. The uninterruptible power supply according to claim 1 or 2, wherein   Furthermore, when the said load current is larger than the said predetermined current, the lower limit limiting circuit which restrict | limits the minimum of the rotation speed of the said cooling fan to the predetermined rotation speed larger than 0 is provided. The uninterruptible power supply according to any one of claims 3 to 4.

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