Uninterruptible power supply device and switch control method

Abstract

To provide an uninterruptible power supply device and a switch control method capable of preventing welding of a mechanical switch.SOLUTION: An uninterruptible power supply (UPS) 1 includes a switching control part 31 that turns on a bypass switch 61 in bypass power feeding via a bypass line 20, and turns off the bypass switch 61 in inverter power feeding. The switching control part 31 simultaneously performs ON control of a mechanical switch 611 and a semiconductor switch 612 at the time of returning from the inverter power feeding to the bypass power feeding, and performs ON control of the mechanical switch 611 after elapse of a period in which an inrush current converges to a predetermined level or less after performing ON control of the semiconductor switch 612 at the time of power-on.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an uninterruptible power supply and a switch control method. [Background technology]

[0002] Patent Document 1 discloses a method for detecting relay welding that can quickly determine whether a relay has welded or not without requiring an auxiliary contact or a dedicated circuit. Patent Document 1 determines whether a relay has welded or not based on whether the frequency deviates from a predetermined range during the synchronization process between the first and second electric circuits that sandwich the relay when a voltage is detected in the first electric circuit (commercial power system) during power supply from an independent output. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-171161 Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional technology is a technique for dealing with relay welding after it has occurred. However, since relay welding can cause equipment failure, there is a need for a technique for preventing relay welding itself.

[0005] An aspect of the present invention is to provide an uninterruptible power supply and a switch control method that can prevent welding of a mechanical switch. [Means for solving the problem]

[0006] An uninterruptible power supply according to one aspect of the present invention includes a bypass switch, which is provided on a bypass line consisting of two lines connecting an input terminal connected to an AC power source and an output terminal connected to a load, and which includes a mechanical switch and a semiconductor switch connected in parallel. The uninterruptible power supply includes a unit that performs inverter power supply, converting AC voltage input to the input terminal into DC voltage to charge a power storage device and converting DC voltage stored in the power storage device into AC voltage to output from the output terminal. The uninterruptible power supply includes a switching control unit that turns on the bypass switch during bypass power supply via the bypass line and turns off the bypass switch during inverter power supply. The switching control unit simultaneously turns on the mechanical switch and the semiconductor switch when returning from the inverter power supply to the bypass power supply. The switching control unit turns on the semiconductor switch when power is turned on, and then turns on the mechanical switch after a period has passed during which an inrush current converges to or below a predetermined level. A switch control method according to one aspect of the present invention controls the on / off of a bypass switch, which is provided in a bypass line consisting of two lines connecting an input terminal connected to an AC power source and an output terminal connected to a load, and which includes a mechanical switch and a semiconductor switch connected in parallel. The switch control method switches between bypass power supply via the bypass line and inverter power supply from a power storage device by turning the bypass switch on and off. The switch control method simultaneously turns on the mechanical switch and the semiconductor switch when returning from the inverter power supply to the bypass power supply. The switch control method turns on the semiconductor switch when power is turned on, and then turns on the mechanical switch after a period has passed during which an inrush current converges to or below a predetermined level. [Effects of the Invention]

[0007] According to one aspect of the present invention, when the mechanical switch is closed (turned on), the inrush current is converged to at least a level that does not cause any problems, so that welding of the mechanical switch can be prevented. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an uninterruptible power supply. [Figure 2] 2 is a diagram showing an inverter power supply state of the uninterruptible power supply device shown in FIG. 1. FIG. [Figure 3] 1. FIG. 4 is a diagram illustrating an ON control at the time of restoration of the switching control unit shown in FIG. [Figure 4] 2 is a diagram illustrating an on-control when power is turned on in the switching control unit shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, components having similar functions will be given the same reference numerals and descriptions thereof will be omitted as appropriate.

[0010] An uninterruptible power supply 1 (hereinafter referred to as UPS 1) of this embodiment is of a continuous commercial power supply type, and with reference to FIG. 1, includes a plurality of units 10a, 10b and a power storage device 100 that supplies backup power in the event of a power outage.

[0011] The power storage device 100 includes, for example, a battery pack in which a plurality of battery cells (secondary batteries such as lithium ion batteries and lead-acid batteries) are connected in series and / or parallel, and a battery management system (BMS) that manages the plurality of battery cells. The power storage device 100 may be configured using a flywheel or a capacitor. There is no limit to the number of power storage devices 100, and the number can be increased or decreased depending on the required backup time.

[0012] The multiple units 10a, 10b may operate independently as a continuous commercial power supply type uninterruptible power supply. The units 10a, 10b are connected in parallel to increase the output capacity of the UPS 1. There is no limit to the number of units 10a, 10b, and they can be increased or decreased depending on the required output capacity.

[0013] The UPS 1 includes a two-line bypass line 20. The bypass line 20 connects an input end 2 (terminal block or inlet) from the AC power source to the UPS 1 and an output end 3 (terminal block or outlet) from the UPS 1 to a load.

[0014] The UPS 1 includes a switch 4 that opens and closes the connection between the AC power source and the bypass line 20 on the upstream side of the bypass line 20. The switch 4 is an input-side bypass switch, and is provided on one of the lines of the two-line bypass line 20. The switch 4 is made up of a relay, which is a mechanical switch that is two lines of the AC circuit, and is turned off in the event of a power outage to prevent voltage from occurring at the input terminal 2 of the UPS 1.

[0015] The UPS 1 includes a rectifier circuit 5, one end of which is connected to the bypass line 20 upstream of the switch 4. The UPS 1 includes a master control unit 30, the other end of which is connected to the rectifier circuit 5. When there is no power outage, the rectifier circuit 5 half-wave rectifies the AC voltage input from one end and supplies the rectified DC voltage (control power) to the master control unit 30. The master control unit 30 is an arithmetic processing circuit such as a microcomputer including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. A control program for controlling the operation of the UPS 1 is stored in the ROM. The master control unit 30 functions as a switching control unit 31 by reading the control program stored in the ROM and loading the control program into the RAM.

[0016] The UPS 1 includes a branch line 21 branching off from the bypass line 20 downstream of the switch 4, and a branch line 22 branching off from the bypass line 20 downstream of the branch point of the branch line 21. Each of the units 10a and 10b has an input terminal T in and a battery connection terminal T connected to the power storage device 100. Batt and the output terminal T connected to the branch line 22. out That is, the plurality of units 10a and 10b are connected in parallel to the bypass line 20.

[0017] Each unit has input terminal T in The input noise filter 11 is provided downstream of the in and output terminal T out An output noise filter 11 provided upstream of the out Each unit includes a charger (CHG) 12, a converter 13, an inverter 14, a control power supply 15, and a slave control unit 16.

[0018] Charger (CHG) 12 is connected to input terminal T in Input noise filter 11 in The charger (CHG) 12 converts the AC voltage input via the charger 12 into a DC voltage and outputs it to the DC power line DC.

[0019] The converter 13 is configured, for example, by an insulated DC-DC converter, and is connected to the downstream side of the charger CHG via a DC power line DC. The DC power line DC is connected to the battery connection terminal T via wiring (not shown) in each of the units 10a and 10b. Batt The converter 13 converts the voltage of the direct current power line DC into a predetermined voltage and supplies it to the inverter 14.

[0020] The inverter 14 converts the DC voltage supplied from the converter 13 into an AC voltage. The AC voltage converted by the inverter 14 is passed through the output-side noise filter 11. out via output terminal T out is output from

[0021] The unit 10a is connected to the input terminal T in and output terminal T out The unit 10a is provided with an individual bypass line 23 that connects the power storage device 100 and the power storage device 100. The unit 10a is provided with a switch 17 that switches between power supply from the individual bypass line 23 and power supply from the power storage device 100 via the inverter 14. The unit 10a can also operate independently as an uninterruptible power supply of a continuous commercial power supply type.

[0022] The UPS 1 may be constructed by using units 10a or 10b with the same configuration for each unit, which can further enhance mass production efficiencies such as improved parts procurement and reduced production costs.

[0023] The UPS 1 includes a bypass switch 61 provided on the bypass line 20 and an inverter switch 62 provided on the branch line 22. The bypass switch 61 is an output-side bypass switch and is provided on a line of the two-wire bypass line 20 where no switch 4 is provided. The bypass switch 61 is provided on the bypass line 20 between the branch point of the branch line 21 and the branch point of the branch line 22. The bypass switch 61 includes a mechanical switch 611 such as a relay, and a semiconductor switch 612 such as a triac or thyristor connected in parallel with the mechanical switch 611. The inverter switch 62 includes a mechanical switch 621 such as a relay, and a semiconductor switch 622 such as a triac or thyristor connected in parallel with the mechanical switch 621.

[0024] UPS1 is connected to the output terminal T of unit 10a. out and the output side switch 7a provided on the AC power line connecting the branch line 22, and the output terminal T out and an output-side switch 7b provided on the AC power line connecting the branch line 22. The output-side switches 7a and 7b are configured by relays, which are mechanical switches.

[0025] The UPS 1 is connected to the inverter switch 62 and the output terminals T of the units 10a and 10b. out The other ends of the rectifier circuits 8a and 8b are connected to the master control unit 30.

[0026] UPS1 is connected to the branch line 21 and the input terminal T of the unit 10a. in and an input side switch 9a provided on the AC power line connecting the branch line 21 and the input terminal T of the unit 10b. inand an input-side switch 9b provided on an AC power line connecting the two. The input-side switches 9a and 9b are configured by relays, which are mechanical switches.

[0027] The slave control unit 16 is an arithmetic processing circuit such as a microcomputer equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The ROM stores a control program for controlling the operation of each of the units 10a and 10b. The slave control unit 16 reads the control program stored in the ROM and loads the control program into the RAM, thereby controlling the operation of each part in each of the units 10a and 10b.

[0028] When the power supply to the UPS 1 is turned on, the master control unit 30 (switching control unit 31) turns on the input side switches 9a, 9b and the output side switches 7a, 7b during the startup sequence. Also, during the startup sequence of the UPS 1, the slave control units 16 of the units 10a, 10b switch the switches 17 to connect the inverter 14 and the output terminal T out Connect with.

[0029] The UPS 1 is powered on during normal operation (non-power outage). Therefore, during the startup sequence, the master control unit 30 (switching control unit 31) turns on the switch 4 and the bypass switch 61 and turns off the inverter switch 62, as shown in Fig. 1, to supply AC voltage from the AC power source to the load via the bypass line 20.

[0030] When the master control unit 30 (switching control unit 31) detects a power outage, it transmits an inverter start-up signal and phase information to the slave control units 16 of each of the units 10a and 10b, and turns off the input-side switches 9a and 9b, as shown in FIG. 2. The slave control units 16 of each of the units 10a and 10b that have received the inverter start-up signal and phase information start up the inverter 14. Next, as shown in FIG. 2, the master control unit 30 (switching control unit 31) turns off the switch 4 and the bypass switch 61, and turns on the inverter switch 62. This switches the bypass power supply, which supplies power from the bypass line 20 to the load, to the inverter power supply, which supplies power from the power storage device 100 to the load via the inverter 14. The switch 17 switches off the inverter 14 and the output terminal T before the power outage is detected. out By connecting these, it is possible to shorten the time required to switch from bypass power supply via the bypass line 20 to inverter power supply. In the event of a power outage (emergency), the rectifier circuits 8a and 8b half-wave rectify the AC voltage input from one end and supply the rectified DC voltage (control power supply) to the master control unit 30.

[0031] When it is detected that the power supply has returned to a non-power outage (normal state), the switching control unit 31 turns the inverter switch 62 off and the switch 4 and the bypass switch 61 on, as shown in FIG. 1, and supplies the AC voltage from the AC power supply to the load via the bypass line 20.

[0032] 3 is a diagram showing the on-control of the switch 4 and the bypass switch 61 by the switching control unit 31 when power is restored from a non-power outage (normal state) (hereinafter referred to as restoration on-control). In FIG. 3, (a) shows the coil voltage that operates the mechanical switch 611 of the bypass switch 61, and (b) shows the drive current that operates the semiconductor switch 612 of the bypass switch 61.

[0033] In the bypass switch 61, the semiconductor switch 612 can close the circuit (switch to the ON state) faster than the mechanical switch 611, but it also generates a large amount of heat and has a high risk of malfunction. Therefore, when performing the ON control at the time of recovery, the switching control unit 31 simultaneously raises the coil voltage of the mechanical switch 611 and the drive current of the semiconductor switch 612, as shown in Fig. 3. By raising the coil voltage and drive current simultaneously, the semiconductor switch 612 closes the circuit (switches ON) faster than the mechanical switch 611, and can be quickly switched so that the power supply to the load is not interrupted.

[0034] After the mechanical switch 611 is closed (ON) by raising the coil voltage, the switching control unit 31 lowers the drive current of the semiconductor switch 612 as shown in Fig. 3. By lowering the drive current, the semiconductor switch 612 is opened (OFF). Thereafter, power is supplied to the load only via the mechanical switch 611, so that heat loss in the semiconductor switch 612 can be reduced and the risk of failure is also reduced.

[0035] The on-control of the switch 4 and the bypass switch 61 is also performed when the UPS 1 is powered on. Fig. 4 is a diagram showing the on-control of the switch 4 and the bypass switch 61 by the switching control unit 31 when the power is turned on (hereinafter referred to as on-control at power-on). In Fig. 4, (a) shows the coil voltage that operates the switch 4, (b) shows the coil voltage that operates the mechanical switch 611 of the bypass switch 61, and (c) shows the drive current that operates the semiconductor switch 612 of the bypass switch 61.

[0036] When the power is turned on, no power is supplied to the load. Therefore, a large inrush current occurs when the switch 4 and the bypass switch 61 are closed (ON). A large inrush current increases the risk of welding the switch 4 and the mechanical switch 611 of the bypass switch 61. Therefore, when performing ON control at power-on, the switching control unit 31 sequentially increases the coil voltage of the switch 4, the drive current of the semiconductor switch 612, and the coil voltage of the mechanical switch 611 at intervals, as shown in FIG.

[0037] Power supply to the load is not initiated by the closing (ON) of the switch 4, but by the closing (ON) of the semiconductor switch 612. When the semiconductor switch 612 is closed (ON), an inrush current flows. A period T1 from the ON control of the semiconductor switch 612 to the ON control of the mechanical switch 611 is set to a time during which the inrush current converges to a level that does not cause any problems, for example, 50 ms. Therefore, when the mechanical switch 611 is closed (ON), the inrush current has converged to at least a level that does not cause any problems, and therefore welding of the mechanical switch 611 can be prevented.

[0038] (summary) (1) A UPS 1 (uninterruptible power supply) according to each embodiment of the present invention includes a bypass line 20 connecting an input terminal 2 connected to an AC power source and an output terminal 3 connected to a load. The UPS 1 includes a bypass switch 61 provided on the bypass line 20, in which a mechanical switch 611 and a semiconductor switch 612 are connected in parallel. The UPS 1 includes units 10a and 10b that perform inverter power supply, converting an AC voltage input to the input terminal 2 into a DC voltage to charge a power storage device 100, and converting the DC voltage stored in the power storage device into an AC voltage to output from the output terminal 3. The UPS 1 includes a switching control unit 31 that turns on the bypass switch 61 during bypass power supply via the bypass line 20 and turns off the bypass switch 61 during inverter power supply. When returning from inverter power supply to bypass power supply, the switching control unit 31 simultaneously turns on the mechanical switch 611 and the semiconductor switch 612. When power is turned on, the switching control unit 31 turns on the semiconductor switch 612, and then turns on the mechanical switch 611 after a period has passed during which the inrush current converges to a predetermined level or less.

[0039] In the UPS 1 described in (1) above, when the power is turned on, the inrush current converges to at least a negligible level when the mechanical switch 611 is closed (ON), preventing the mechanical switch from welding. When the UPS 1 recovers, the semiconductor switch 612 closes (ON) at a higher speed than the mechanical switch 611, enabling quick switching so that the power supply to the load is not interrupted.

[0040] (2) In addition to the UPS 1 described in (1) above, the switching control unit 31 controls the semiconductor switch 612 to turn off after the mechanical switch 611 is turned on, both at the time of recovery and at the time of power-on.

[0041] The UPS 1 described in (2) above can reduce the heat loss of the semiconductor switch 612, and also reduces the risk of failure.

[0042] (3) A switch control method according to each embodiment of the present invention controls on / off of a bypass switch 61 provided on a bypass line 20 connecting an input terminal 2 connected to an AC power supply and an output terminal 3 connected to a load. The bypass switch 61 has a mechanical switch 611 and a semiconductor switch 612 connected in parallel. The switch control method switches between bypass power feeding via the bypass line 20 and inverter power feeding from the power storage device 100 by turning on / off the bypass switch 61. The switch control method simultaneously controls on the mechanical switch 611 and the semiconductor switch 612 when returning from inverter power feeding to bypass power feeding. The switch control method controls on the semiconductor switch 612 when power is turned on, and then controls on the mechanical switch 611 after a period has passed during which an inrush current converges to a predetermined level or less.

[0043] The switch control method described in (3) above can prevent welding of the mechanical switch when the mechanical switch 611 is closed (ON) at power-on because the inrush current converges to at least a negligible level. When the UPS 1 recovers, the semiconductor switch 612 is closed (ON) at a higher speed than the mechanical switch 611, enabling quick switching so as not to interrupt the power supply to the load.

[0044] Although the present invention has been described above with reference to specific embodiments, it goes without saying that the above embodiments are merely examples and can be modified and implemented without departing from the spirit of the present invention. [Explanation of symbols]

[0045] 1 Uninterruptible power supply (UPS) 2 input terminals 3 Output terminal 4 Switches 5 Rectifier circuit 7a, 7b Output side switches 8a, 8b rectifier circuit 9a, 9b Input side switches 10a, 10b units 11in input noise filter 11out Output noise filter 12 Charger (CHG) 13 Converter 14 Inverter 15 Control power supply 16 Slave control unit 17 Switch 20 Bypass Line 21, 22 Branch lines 23 Individual bypass line 30 Master control unit 31 Switching control section 32 Short circuit fault detection section 41 Input voltage detector 42 Bypass voltage detector 43 Load voltage detector 44 Bus voltage detector 61 Bypass switch 62 Inverter switch 100 Electricity storage device 611, 621 Mechanical Switches 612, 622 Semiconductor switches

Claims

1. a bypass switch, which is provided in a bypass line consisting of two lines connecting an input end connected to an AC power supply and an output end connected to a load, and which includes a mechanical switch and a semiconductor switch connected in parallel; a unit that performs inverter power supply, which converts an AC voltage input to the input terminal into a DC voltage to charge a power storage device, and converts the DC voltage stored in the power storage device into an AC voltage to output from the output terminal; a switching control unit that turns on the bypass switch in bypass power feeding via the bypass line and turns off the bypass switch in inverter power feeding, The switching control unit simultaneously controls to turn on the mechanical switch and the semiconductor switch when returning from the inverter power supply to the bypass power supply, and when power is turned on, after controlling to turn on the semiconductor switch, controls to turn on the mechanical switch after a period has passed during which an inrush current converges to a predetermined level or less.

2. 2. The uninterruptible power supply according to claim 1, wherein the switching control unit controls the semiconductor switch to be turned off after the mechanical switch is turned on both at the time of the recovery and at the time of the power-on.

3. A switch control method for switching between bypass power supply via the bypass line and inverter power supply from a power storage device by turning on and off a bypass switch, the bypass switch being provided in a bypass line consisting of two lines connecting an input end connected to an AC power supply and an output end connected to a load, the bypass switch comprising a mechanical switch and a semiconductor switch connected in parallel, the method comprising: a switch control method for simultaneously controlling the mechanical switch and the semiconductor switch to be on when returning from the inverter power supply to the bypass power supply, and for controlling the semiconductor switch to be on when power is turned on, and then controlling the mechanical switch to be on after a period has passed during which an inrush current converges to a predetermined level or less.

Images