JP5292599B2 - Uninterruptible power system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an uninterruptible power supply unit with high efficiency that extends the service life of a cooling fan. <P>SOLUTION: The uninterruptible power supply unit includes a main inverter 12 for supplying AC power to a load 32 and a sub-inverter 23 for supplying AC power to a cooling fan 24. If a load current I is larger than a threshold current Ith, the power supply unit controls the sub-inverter 23 to control the number of rotations of the cooling fan 24 so that a temperature T in a casing 1 may not exceed a predetermined temperature T0. If the load current I is smaller than the threshold current Ith, the power supply unit controls the sub-inverter 23 to intermittently drive the cooling fan 24. Accordingly, the efficiency of the uninterruptible power supply unit is improved to extend the service life of the cooling fan 24, compared to a conventional power supply unit in which the cooling fan 24 is always driven at a rated number of rotations. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

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 of the desired voltage at the time, and when the sub-inverter is not malfunctioning are driven by the third AC power, and when the sub-inverter is malfunctioning, the second AC power is is driven by a portion, forming a cooling fan for cooling the housing, the normal time binds the the sub inverter cooling fan, the failure is the main inverter and the cooling fan A switching circuit for a temperature sensor for detecting the temperature in the housing, a current sensor for detecting a load current, the normal, when the load current detected by the current sensor is larger than the current that is determined in advance, the temperature Control the sub inverter to control the rotation speed of the cooling fan so that the detected temperature of the sensor does not exceed the predetermined temperature. If the load current is smaller than the predetermined current, the detected temperature of the temperature sensor Regardless of the control circuit, the control circuit includes a control circuit that controls the sub inverter and drives the cooling fan intermittently.

  Preferably, 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. Increase.

Also preferably, further, the rotational speed of the lower limit of the cooling fan comprises a lower limiting circuit for setting the rotational speed that is determined greater advance than 0, the control circuit, the load current detected by the current sensor is predetermined It was larger than current Ru driven at a higher rotational speed than the rotational speed that is determined cooling fan in advance.

  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.

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 30a of the battery 30. The battery 30 is housed in a housing 31 different from the housing 1. A load 32 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 30, and protects the converter 8 , the main inverter 12, the battery 30, and the like. The switch 10 is controlled by the main control circuit 4 and is turned on when the battery 30 is charged and discharged, and turned off when the battery 30 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 30. 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 32. Further, the transformer 13 and the capacitor 14 constitute an output filter, cut off the carrier frequency signal generated in the main inverter 12, and prevent the carrier frequency signal from adversely affecting the load 32.

  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 32. The switch 16 is controlled by the main control circuit 4 and is turned on in the bypass power supply mode in which AC power supplied from the AC power supply via the bypass input terminal T1 is supplied to the load 32. 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 32.

In addition, a setter 20, a signal generation circuit 21, a sub control circuit 22, a sub inverter 23, a cooling fan 24, a current sensor 25, and a temperature sensor 26 are further provided in the housing 1. Secondary inverter 23 is controlled by the sub-control circuit 22 converts direct current power generated by the converter 8, or a DC power supplied from the battery 30 into AC power of a desired voltage at the desired frequency. The cooling fan 24 is driven by the AC power generated by the sub inverter 23, 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 23 are increased, the rotational speed of the cooling fan 24 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 23 are lowered, the number of rotations of the cooling fan 24 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 24 can be controlled by controlling the frequency and voltage of the output of the sub inverter 23, and the temperature in the housing 1 can be adjusted. Note that the ratio of the frequency and voltage of the output of the sub inverter 23 is controlled to be constant.

  The current sensor 25 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 26 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 25 is smaller than the threshold current Ith that is sufficiently smaller than the rated current, the signal generating circuit 21 controls the control signal φR having a predetermined frequency for intermittently operating the cooling fan 24. 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 23 according to the control signal φR to drive the cooling fan 24 intermittently. In this case, the rotational speed of the cooling fan 24 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 setter 20, the rotation speed of the cooling fan 24 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 24 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 temperature T detected by the temperature sensor 26. Thus, the sub inverter 23 is controlled to control the rotation speed of the cooling fan 24.

  Next, the operation of this uninterruptible power supply will be described. When the uninterruptible power supply is started, switches 5 and 10 are first turned on, converter 8 is operated, and capacitor 11 and battery 30 are charged. When charging of the capacitor 11 and the battery 30 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 32 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 30 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 32.

  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 30 is supplied to the main inverter 12. The main inverter 12 converts DC power supplied from the battery 30 into AC power having a constant frequency and a constant voltage, and supplies the AC power to the load 32. Thus, even when a power failure occurs, as long as DC power is stored in the battery 30, the operation of the load 32 can be continued. 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 source via the bypass input terminal T1 is instantaneously applied to the load 32. 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 32 in the bypass power supply mode.

  Further, when the uninterruptible power supply is operated and current is supplied to the load 32, 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 23 to control the rotation speed of the cooling fan 24 so that the temperature T detected by the temperature sensor 26 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 24 increases. When the temperature in the housing 1 decreases below the predetermined temperature T0, the rotational speed of the cooling fan 24 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.

  In this embodiment, in addition to the main inverter 12 that drives the load 32, a sub-inverter 23 that drives the cooling fan 24 is provided, so that the temperature T in the housing 1 does not exceed a predetermined temperature T0. To control the rotational speed of the cooling fan 24. When the load current I is smaller than the threshold current Ith, the cooling fan 23 is operated intermittently. The power consumption of the cooling fan 24 is proportional to the cube of the rotational speed, and the life of the cooling fan 24 is determined by the product of the rotational speed and time. Therefore, the power consumption of the cooling fan 24 is reduced, the efficiency of the uninterruptible power supply device is increased, and the life of the cooling fan 24 is extended as compared with the conventional case where the cooling fan 24 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 24 is operated intermittently. When the capacity of the load 32 is smaller than the rated value, the cooling fan 24 is driven to rotate at a rotational speed smaller than the rated rotational speed. Therefore, even in these cases, the cooling fan 24 is always driven to rotate at the rated rotational speed, and the power consumption of the cooling fan 24 can be reduced in the present embodiment as compared with the conventional case.

  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 27 is added. The lower limit circuit 27 is operated by the user of the uninterruptible power supply. The lower limit circuit 27 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 24 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 24, 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 the predetermined temperature T0 based on the temperature T detected by the temperature sensor 26. The sub inverter 23 is controlled to control the rotation speed of the cooling fan 24.

Further, the sub-control circuit 22, when the load current I is greater than the threshold current Ith limits the lower limit of the frequency of the output of the auxiliary inverter 23 to a predetermined frequency higher than 0, the rotation of the cooling fan 24 The lower limit of the number is limited to a predetermined rotational speed RL greater than zero. In this modified example, since the rotation speed of the cooling fan 24 is set to be larger than the predetermined lower limit value RL, even if the temperature sensor 26 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 switches 28 and 29 are added. The switch 28 is connected between the output node of the sub inverter 23 and the input node of the cooling fan 24, and the switch 29 is connected between the output node of the main inverter 12 and the input node of the cooling fan 24.

  If the sub inverter 23 has not failed, the sub control circuit 22 turns on the switch 28 and turns off the switch 29, and supplies the AC power generated by the sub inverter 23 to the cooling fan 24. In addition, when the sub inverter 23 fails, the sub control circuit 22 turns off the switch 28 and turns on the switch 29, and supplies the AC power generated by the main inverter 12 to the cooling fan 24. In this modified example, when the sub inverter 23 fails, the cooling fan 24 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 27 and switches 28 and 29 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.

  1,31 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, 28, 29 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, 23 Sub Inverter, 24 cooling fan, 25 current sensor, 26 temperature sensor, 27 lower limit circuit, 30 battery, 32 load.

Claims (3)

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;
The sub-inverter is driven by the third AC power when it is normal and the sub-inverter is driven by a part of the second AC power when the sub-inverter is faulty to cool the casing. With fans,
A switching circuit for coupling the sub inverter and the cooling fan at the normal time, and coupling the main inverter and the cooling fan at the time of the failure;
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 larger than a predetermined current at the normal time, the sub-inverter is controlled so that the temperature detected by the temperature sensor does not exceed the predetermined temperature. Then, when the rotation speed of the cooling fan is controlled and the load current is smaller than the predetermined current, the cooling fan is intermittently controlled by controlling the sub inverter regardless of the temperature detected by the temperature sensor. And an uninterruptible power supply device.   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, wherein the uninterruptible power supply is increased. Further, the rotational speed of the lower limit of the previous SL cooling fan comprises a lower limiting circuit for setting the rotational speed that is determined greater advance than 0,
Wherein the control circuit, the when the current the load current detected by the sensor is the greater than the predetermined current, the Ru cooling fan is driven at a higher rotational speed than the rotational speed of the predetermined billing The uninterruptible power supply according to claim 1 or claim 2.

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