JP4789376B2 - Power switching device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply switching device capable of switching between two different AC power supply systems, and particularly when the load side is short-circuited and an overcurrent is detected, the power supply switching operation is interlocked, The present invention relates to a power supply switching device that can immediately restore the load power supply from the other healthy power supply system after the trouble such as a short circuit on the load side is solved by not affecting the power supply system. .
[0002]
[Prior art]
FIG. 7 is a block circuit diagram showing a configuration example of a conventional uninterruptible power supply.
[0003]
In FIG. 7, the output of the inverter 1 is connected to one winding of the inverter transformer 2.
[0004]
The other winding of the inverter transformer 2 is an output of the uninterruptible power supply and is connected to the output of the switching circuit 3.
[0005]
The switching circuit 3 includes a contactor 4 and a semiconductor switch 5, and is used to switch the power supply to the load 6 from the inverter 1 or the commercial power source 7.
[0006]
Although the contactor 4 is described as a double-headed type, a single-headed contactor may be attached to the inverter 1 and the commercial power source 7 as long as the power supply system can be switched.
[0007]
The DC power source 9 may be a converter, a storage battery, or the like as long as it can constitute a DC voltage source.
[0008]
On the other hand, a voltage detector 8 a is connected to the other winding of the inverter transformer 2.
[0009]
The output of the voltage detector 8 a is input to the inverter control circuit 11 and input to the output voltage control circuit 22 in the inverter control circuit 11 as the output voltage feedback 31.
[0010]
The output of the reference generation circuit 21 in the inverter control circuit 11 is input to the output voltage control circuit 22 as the output voltage reference 32.
[0011]
Further, in order to operate the inverter output voltage in synchronization with the commercial power supply, the output of the voltage detector 8b is input to the PLL circuit 23, and the output of the PLL circuit 23 is input to the output voltage control circuit 22 as the output voltage phase 33. ing.
[0012]
The output of the output voltage control circuit 22 is input to the gate control circuit 24 as an output voltage command 34.
[0013]
Further, the output of the gate control circuit 24 is input to the inverter 1 as a gate signal 35.
[0014]
In FIG. 7, the reference generation circuit 21 outputs an output voltage reference 32 corresponding to the voltage that the uninterruptible power supply should output.
[0015]
The output voltage control circuit 22 performs control so that the output voltage feedback 31 detected by the voltage detector 8a is equal to the output voltage reference 32, and outputs an output voltage command 34.
[0016]
The gate control circuit 24 outputs a gate signal 35 so that the output of the inverter 1 matches the output voltage command 34.
[0017]
The inverter 1 performs an output 36 corresponding to the gate signal 35, and the output converted by the winding configuration, winding ratio, etc. of the inverter transformer 2 becomes the output of the uninterruptible power supply.
[0018]
FIG. 8 is a circuit diagram showing a configuration example of the inverter 1.
[0019]
In FIG. 8, the positive electrode P of the DC power supply 9 is connected to one terminal of the DC capacitor 41.
[0020]
Further, the positive electrode P of the DC power supply 9 is connected to the collectors of the switching elements 42a, 42c, and 42e, respectively.
[0021]
Furthermore, these are the inverter outputs 36 as U phase, V phase and W phase, respectively.
[0022]
The emitters of the switching elements 42 b, 42 d, 42 f are connected to the other terminal of the DC capacitor 41 and further connected to the negative electrode N of the DC power supply 9.
[0023]
Further, the gate signal 35 is input to the gate drive circuit 43.
[0024]
Note that each switching element 42b, 42d, 42f is provided with a snubber circuit for suppressing surge voltage during switching individually or collectively, but the illustration thereof is omitted here for the sake of simplicity. ing.
[0025]
In response to the gate signal 35, the gate drive circuit 43 generates a dead time that prevents the switching elements connected in series vertically, for example, 42a, 42b, etc., from being turned on at the same time, and the charge / discharge period of each snubber circuit Or to secure.
[0026]
The inverter 1 controls the output voltage by pulse width modulation (PWM).
[0027]
FIG. 9 is a block diagram illustrating a configuration example of the reference generation circuit 21 in the inverter control circuit 11.
[0028]
In FIG. 9, the outputs of the voltage reference signals 51a to 51c are input to the multipliers 53a to 53c, respectively.
[0029]
The outputs of the multipliers 53a to 53c become the reference generation circuit output 32.
[0030]
FIG. 9 is an example of a case in which three phases of U phase, V phase, and W phase are configured, and shows an example of outputting a constant sine wave voltage.
[0031]
There may be a case where the voltage reference changes with time (for example, VVVF... Variable voltage variable frequency power supply).
[0032]
The soft start signal 52 is a signal that gradually increases the output voltage from zero when the inverter 1 is started, and is a temporary increase function such as a ramp function during the start-up period, and becomes a constant value such as 1 after the start-up is completed.
[0033]
With this circuit, the uninterruptible power source can gradually increase the output voltage at the time of startup. This is a technique generally called soft start.
[0034]
FIG. 10 is a block diagram illustrating a configuration example of the output voltage control circuit 22 in the inverter control circuit 11.
[0035]
In FIG. 10, the output voltage reference 32 has a difference from the output voltage feedback 31, and is input to the PI control circuits 54a to 54c.
[0036]
In this example, an example is shown in which P1 control is used as voltage control, but other general control methods such as PID control and I-P control, and control circuits using modern control theory may be used. .
[0037]
In FIG. 10, PI control circuits 54 a to 54 c perform control so that the output voltage feedback 31 follows the output voltage reference 32.
[0038]
In particular, a current control circuit such as an output current may be added after the output voltage, before the output voltage, or in parallel in order to increase the speed and stability. Here, it is omitted for the sake of simplicity.
[0039]
FIG. 11 is a block diagram illustrating a configuration example of the gate control circuit 24 in the inverter control circuit 11.
[0040]
In FIG. 11, the output voltage command 34 is input to the comparators 56a to 56c after the difference from the carrier generation circuit 55 is obtained.
[0041]
Outputs of the comparators 56a to 56c are input to the gate control circuits 57a to 57c.
[0042]
The outputs of the gate control circuits 57a to 57c are the gate signal 35.
[0043]
This configuration example is an example showing a generally-known triangular wave comparison method. The method for generating the gate pulse is not particularly limited.
[0044]
FIG. 12 is a block circuit diagram showing a configuration example of a conventional power supply switching device.
[0045]
In FIG. 12, the power supply switching device is used as an input power source for the power supply system of the uninterruptible power supply devices 61a and 61b.
[0046]
The switching circuit 3 includes a contactor 4 and semiconductor switches 5a and 5b, and supplies power to the load 6 by supplying the one uninterruptible power supply (system A) 61a and the other uninterruptible power supply ( B system) Used to operate to switch power supply to any of 61b.
[0047]
In order to suppress the current flowing between the power supply systems, a reactor may be loaded in series with the semiconductor switches 5a and 5b, but this is omitted here for the sake of simplicity.
[0048]
When the uninterruptible power supply (system A) 61a supplies power to the load 6, the switching control circuit 60 detects a power failure when the power failure detection circuit 62a that receives the output of the voltage detector 8a detects a voltage drop. The signal 63a is output and input as a set signal of the signal holding circuit 64b.
[0049]
Here, the signal holding circuit 64b is composed of an RS flip-flop circuit, and performs output setting (“1”) and resetting (“0”) according to the input signal.
[0050]
The input of the signal holding circuit 64b is given priority to the reset signal, and when both the set (S) input and reset (R) input are simultaneously given, the reset signal is given priority.
[0051]
The output of the signal signal holding circuit 64b becomes the switching control signal 65b, and the contactor 4 and the semiconductor switches 5a and 5b in the switching circuit 3 are operated in order to switch the power supply to the B system side.
[0052]
The switching control signal 65a performs a switching operation on the uninterruptible power supply (A system) 61a side, and the switching signal 65b performs a switching operation on the uninterruptible power supply (B system) 61b side.
[0053]
Since the output of the manual operation circuit 66b is the same as that of the power failure signal 63a, the power supply switching from the uninterruptible power supply (B system) 61b to the load 6 can be switched by inputting this manual operation signal. Can be done.
[0054]
Further, the power failure detection signal 63b and the output of the manual operation circuit 66a, which have not been described, serve as a power supply switching signal for the uninterruptible power supply (system A) 6.
[0055]
[Problems to be solved by the invention]
However, in the conventional power supply switching apparatus as described above, when a short circuit occurs on the load 6 side and an overcurrent occurs, the power supply system is in a voltage drop state, and the power supply is switched to the other healthy power supply system. become.
[0056]
At this time, when the short circuit on the load 6 side continues, the other healthy power supply system cannot be fed and the system is stopped.
[0057]
In addition, after the short circuit on the load 6 side is resolved, inspection and restarting operation on the power system side are required, and it takes a long time to restore the load power supply.
[0058]
The object of the present invention is to short-circuit the load side by interlocking the power feeding switching operation so that the other healthy power system is not affected when the load side is short-circuited and an overcurrent is detected. An object of the present invention is to provide a power supply switching device capable of immediately recovering load power supply from another healthy power supply system after such problems as above are resolved.
[0059]
[Means for Solving the Problems]
In order to achieve the above object, a power supply switching device according to the present invention includes a first power supply for supplying power to a load, a second power supply for supplying power to the load, and power supplied to the load. Switching means for switching between the power from the first power source and the power from the second power source; first voltage drop detecting means for detecting a voltage drop of the first power source; and the first voltage. When a voltage drop is detected by the drop detecting means, a first switching operation is performed by the switching means to switch the power supplied to the load from the power supplied from the first power supply to the power supplied from the second power supply. A first switching operation means for outputting a command; a second voltage drop detecting means for detecting a voltage drop of the second power supply; and a voltage drop detected by the second voltage drop detecting means. By means A second switching operation means for outputting a second switching command for switching the power supplied to the load from the power from the second power source to the power from the first power source; When overcurrent is detected by the overcurrent detection means for detecting an overcurrent of the current and the overcurrent detection means, In a state where power supply is continued from the first power source or the second power source to the load, Lock means for locking both the output of the first switching command by the first switching operation means and the output of the second switching command by the second switching operation means.
[0072]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0073]
(First embodiment)
FIG. 1 is a block circuit diagram showing a configuration example of a power supply switching device according to the present embodiment. The same parts as those in FIG. 12 are denoted by the same reference numerals, and the description thereof is omitted. Only different parts will be described here.
[0074]
That is, as shown in FIG. 1, the power supply switching apparatus according to the present embodiment includes a current detector 71 as current detection means, an overcurrent detection circuit 72 as overcurrent determination means, and a hold circuit 73a as lock means. And 73b are added to FIG.
[0075]
The current detector 71 detects the output current of the power supply switching device main body.
[0076]
When the overcurrent detection circuit 72 determines that the output from the current detector 71 is equal to or higher than a predetermined constant level, that is, for example, greater than twice the rated current of the power supply switching device body, the overcurrent detection output is set to a predetermined value. Occurs.
[0077]
When the overcurrent detection output from the overcurrent detection circuit 72 is input, the hold circuits 73a and 73b lock the power supply switching operation of the switching circuit 3 by the input, that is, hold the switching control signals 65a and 65b.
[0078]
In this example, the output of the overcurrent detection output has a one-shot pulse configuration. However, the present invention is not limited to this. For example, the output of the overcurrent detection output may be latched by a signal holding circuit or the like. Absent.
[0079]
Next, the operation of the power supply switching device according to the present embodiment configured as described above will be described.
[0080]
In FIG. 1, the output current of the power supply switching device main body is detected by a current detector 71, and if this current detection value is equal to or greater than a predetermined set value, the overcurrent detection circuit 72 can determine that it is an overcurrent. .
[0081]
In such an overcurrent detection state, the overcurrent detection circuit 72 outputs a signal that has been latched for a certain period of time, and holds the switching control signals 65a and 65b of the switching circuit 3 by the hold circuits 73a and 73b.
[0082]
Thereby, even when an overcurrent due to a load short circuit or the like occurs and one power supply system detects a voltage drop, the other healthy power supply system can be maintained.
[0083]
As described above, in the power supply switching device according to the present embodiment, the interlock circuit of the power supply switching device body is operated in response to the occurrence of an abnormality due to a load-side short circuit or the like. Since the system can be protected and the load-side power supply can be easily restored after the load-side abnormality is resolved, the load-power-supply reliability can be improved.
[0084]
That is, for example, even when a transient overcurrent state, that is, a temporary short circuit state on the load side, is caused by a rush current caused by turning on the transformer on the load side or starting the motor, the power supply switching device is switched to the other healthy power system. Since power supply is continued without performing a power supply switching operation, a restoration operation for load power supply becomes unnecessary, and power supply reliability can be improved.
[0085]
(Second Embodiment)
FIG. 2 is a block circuit diagram showing a configuration example of the power supply switching device according to the present embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals and the description thereof is omitted. Only different parts will be described here.
[0086]
That is, in the power supply switching device according to the present embodiment, as shown in FIG. 2, the contactor 4 in FIG. 1 is omitted, and the switching circuit 3 is configured only by the semiconductor switches 5a and 5b.
[0087]
Next, the operation of the power supply switching device according to the present embodiment configured as described above will be described.
[0088]
In FIG. 2, the output current of the power supply switching device main body is detected by the current detector 71, and if this current detection value is equal to or greater than a predetermined set value, the overcurrent detection circuit 72 can determine that it is an overcurrent. .
[0089]
In such an overcurrent detection state, the overcurrent detection circuit 72 outputs a signal that has been latched for a certain period of time, and holds the switching control signals 65a and 65b of the switching circuit 3 by the hold circuits 73a and 73b.
[0090]
Thereby, even when an overcurrent due to a load short circuit or the like occurs and one power supply system detects a voltage drop, the other healthy power supply system can be maintained.
[0091]
As described above, the power switching device according to the present embodiment can achieve the same effects as those of the power switching device according to the first embodiment described above.
[0092]
(Third embodiment)
FIG. 3 is a block circuit diagram showing a configuration example of the power supply switching apparatus according to the present embodiment. The same parts as those in FIG. 12 are denoted by the same reference numerals, and the description thereof is omitted. Only different parts will be described here.
[0093]
In other words, as shown in FIG. 3, the power supply switching apparatus according to the present embodiment has a configuration in which a switch circuit 74 as manual operation means and hold circuits 73a and 73b as lock means are added to FIG. .
[0094]
The switch circuit 74 prompts input of a signal by manual operation.
[0095]
When a signal by a manual operation is input from the switch circuit 74, the hold circuits 73a and 73b lock the power feeding switching operation of the switching circuit 3 during the input of the input signal by the input signal, that is, the switching control signals 65a and 65b. Hold.
[0096]
Next, the operation of the power supply switching device according to the present embodiment configured as described above will be described.
[0097]
In FIG. 3, when a signal by manual operation is input from the switch circuit 74, the hold control signals 65a and 65b of the switching circuit 3 are held by the hold circuits 73a and 73b by the input signal while the input signal is being input.
[0098]
Thereby, even when an overcurrent due to a load short circuit or the like occurs and one power supply system detects a voltage drop, the other healthy power supply system can be maintained.
[0099]
As described above, in the power supply switching device according to the present embodiment, in addition to an unexpected short circuit on the load side, a case where an overcurrent is generated in advance and the power supply system can be expected to detect a voltage drop, for example, the load side In the case of rush current due to turning on the transformer, overcurrent at start-up due to motor start-up and load short-circuit due to erroneous operation when checking the load side equipment, the switching control signals 65a and 65b of the power source switching device main body are held only during the load equipment operation time zone. As a result, the other healthy power supply system can be prevented from being adversely affected, and the load power supply can be easily restored after the load side is eliminated.
[0100]
(Fourth embodiment)
FIG. 4 is a block circuit diagram showing a configuration example of the power supply switching device according to the present embodiment. The same parts as those in FIG. 3 are denoted by the same reference numerals and the description thereof is omitted, and only different parts are described here.
[0101]
That is, in the power supply switching device according to the present embodiment, as shown in FIG. 4, the contactor 4 in FIG. 3 is omitted, and the switching circuit 3 is configured only by the semiconductor switches 5a and 5b.
[0102]
Next, the operation of the power supply switching device according to the present embodiment configured as described above will be described.
[0103]
In FIG. 4, when a signal by manual operation is input from the switch circuit 74, the hold control signals 65a and 65b of the switching circuit 3 are held by the hold circuits 73a and 73b by the input signal while the input signal is being input.
[0104]
Thereby, even when an overcurrent due to a load short circuit or the like occurs and one power supply system detects a voltage drop, the other healthy power supply system can be maintained.
[0105]
As described above, the power switching device according to the present embodiment can obtain the same effects as those of the power switching device according to the third embodiment described above.
[0106]
(Fifth embodiment)
FIG. 5 is a block circuit diagram showing a configuration example of the power supply switching device according to the present embodiment. The same parts as those in FIG. 12 are denoted by the same reference numerals and the description thereof is omitted, and only different parts are described here.
[0107]
That is, as shown in FIG. 5, the power supply switching apparatus according to the present embodiment includes a current detector 71 as current detection means, an overcurrent detection circuit 72 as overcurrent determination means, and a switch circuit as manual operation means. 74, a logical sum (OR) circuit 75, and hold circuits 73a and 73b as lock means are added to FIG.
[0108]
The current detector 71 detects the output current of the power supply switching device main body.
[0109]
When the overcurrent detection circuit 72 determines that the output from the current detector 71 is equal to or higher than a predetermined constant level, that is, for example, greater than twice the rated current of the power supply switching device body, the overcurrent detection output is set to a predetermined value. Of time.
[0110]
The switch circuit 74 prompts input of a signal by manual operation.
[0111]
A logical sum (OR) circuit 75 receives an overcurrent detection output from the overcurrent detection circuit 72 and a signal by manual operation from the switch circuit 74, and outputs a logical sum signal of both.
[0112]
When the logical sum signal from the logical sum (OR) circuit 75 is input, the hold circuits 73a and 73b lock the power supply switching operation of the switching circuit 3 by the input, that is, hold the switching control signals 65a and 65b.
[0113]
In this example, the output of the overcurrent detection output has a one-shot pulse configuration. However, the present invention is not limited to this. For example, the output of the overcurrent detection output may be latched by a signal holding circuit or the like. Absent.
[0114]
Next, the operation of the power supply switching device according to the present embodiment configured as described above will be described.
[0115]
In FIG. 5, the output current of the power supply switching device main body is detected by the current detector 71, and if this current detection value is equal to or greater than a predetermined set value, the overcurrent detection circuit 72 can determine that it is an overcurrent. .
[0116]
In such an overcurrent detection state, the overcurrent detection circuit 72 outputs a signal that has been latched for a certain period of time or via the OR circuit 75, and the hold circuits 73a and 73b cause the switching circuit 3 to The switching control signals 65a and 65b are held.
[0117]
On the other hand, when a signal by manual operation is input from the switch circuit 74, the switching control of the switching circuit 3 is performed by the hold circuits 73a and 73b via the OR circuit 75 while the input signal is being input by this input signal. The signals 65a and 65b are held.
[0118]
As described above, in the power supply switching device according to the present embodiment, the interlock circuit of the power supply switching device body is operated in response to the occurrence of an abnormality due to a load-side short circuit or the like. Since the system can be protected and the load-side power supply can be easily restored after the load-side abnormality is resolved, the load-power-supply reliability can be improved.
[0119]
That is, for example, even when a transient overcurrent state, that is, a temporary short circuit state on the load side, is caused by a rush current caused by turning on the transformer on the load side or starting the motor, Since power supply is continued without performing a power supply switching operation, a restoration operation for load power supply becomes unnecessary, and power supply reliability can be improved.
[0120]
In addition to unexpected short-circuits on the load side, a case where an overcurrent occurs in advance and the power supply system can be expected to detect a voltage drop, for example, a rush current due to turning on the load-side transformer or an excessive start-up due to motor startup. In the case of a load short circuit due to an erroneous operation during inspection of the current and load side equipment, the switching control signals 65a and 65b of the power supply switching device main body are held only during the load equipment operation time period. It is possible to prevent adverse effects on the system, and it is possible to easily restore the load power supply after the load side is eliminated.
[0121]
(Sixth embodiment)
FIG. 6 is a block circuit diagram showing a configuration example of the power supply switching device according to the present embodiment. The same parts as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted. Only different parts will be described here.
[0122]
That is, in the power supply switching apparatus according to the present embodiment, as shown in FIG. 6, the contactor 4 in FIG. 5 is omitted, and the switching circuit 3 is configured only by the semiconductor switches 5a and 5b.
[0123]
Next, the operation of the power supply switching device according to the present embodiment configured as described above will be described.
[0124]
In FIG. 6, the output current of the power supply switching device main body is detected by the current detector 71, and if this current detection value is equal to or greater than a predetermined set value, the overcurrent detection circuit 72 can determine that it is an overcurrent. .
[0125]
In such an overcurrent detection state, the overcurrent detection circuit 72 outputs a signal that has been latched for a certain period of time or via the OR circuit 75, and the hold circuits 73a and 73b cause the switching circuit 3 to The switching control signals 65a and 65b are held.
[0126]
On the other hand, when a signal by manual operation is input from the switch circuit 74, the switching control of the switching circuit 3 is performed by the hold circuits 73a and 73b via the OR circuit 75 while the input signal is being input by this input signal. The signals 65a and 65b are held.
[0127]
As described above, the power switching device according to the present embodiment can achieve the same effects as those of the power switching device according to the fifth embodiment described above.
[0128]
(Other embodiments)
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation.
In addition, the embodiments may be implemented in appropriate combinations as much as possible, and in that case, combined effects can be obtained.
Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.
For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem (at least one) described in the column of the problem to be solved by the invention can be solved, and the effect of the invention can be solved. When (at least one of) the effects described in the column can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.
[0129]
【The invention's effect】
As described above, according to the power supply switching device of the present invention, when an overcurrent occurs due to a short circuit in the load and the power supply system detects a voltage drop, the power supply switching operation is interlocked by overcurrent detection or the like. So, because it protects a healthy power supply system and the load-side abnormality is resolved, load power supply can be resumed quickly, and the expansion of short-circuit accidents to the upper system can be prevented. It is possible to improve load power supply reliability.
[0130]
In addition to unexpected short-circuits on the load side, overcurrent can occur in advance and the power supply system can be expected to detect a voltage drop.For example, a rush current due to turning on the load-side transformer or an overcurrent at start-up due to motor startup In the case of load short-circuiting due to incorrect operation when checking the load-side equipment, the power supply switching control signal is held only during the load equipment operation time period, so that it does not adversely affect a healthy power system. It is possible to recover load power supply after the abnormalities on the load side have been resolved and to prevent the occurrence of a short-circuit accident to the host system, thereby improving load power supply reliability. Become.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a first embodiment of a power supply switching device according to the present invention.
FIG. 2 is a block circuit diagram showing a second embodiment of a power supply switching device according to the present invention.
FIG. 3 is a block circuit diagram showing a third embodiment of a power supply switching device according to the present invention.
FIG. 4 is a block circuit diagram showing a fourth embodiment of a power supply switching device according to the present invention.
FIG. 5 is a block circuit diagram showing a fifth embodiment of a power supply switching device according to the present invention.
FIG. 6 is a block circuit diagram showing a sixth embodiment of a power supply switching device according to the present invention.
FIG. 7 is a block circuit diagram showing a configuration example of a conventional uninterruptible power supply.
FIG. 8 is a circuit diagram showing a configuration example of an inverter of a conventional uninterruptible power supply.
FIG. 9 is a block diagram showing a configuration example of a reference generation circuit in an inverter control circuit used in a conventional uninterruptible power supply device.
FIG. 10 is a block diagram showing a configuration example of an output voltage control circuit in an inverter control circuit used in a conventional uninterruptible power supply device.
FIG. 11 is a block diagram showing a configuration example of a gate control circuit in an inverter control circuit used in a conventional uninterruptible power supply device.
FIG. 12 is a block circuit diagram showing a configuration example of a conventional power supply switching device.
[Explanation of symbols]
1 ... Inverter
2 ... Inverter transformer
3. Switching circuit
4 ... Contactor
5 ... Semiconductor switch
6 ... Load
7. Commercial power supply
8 ... Voltage detector
9 ... DC power supply
11 ... Inverter control circuit
21. Reference generation circuit
22 ... Output voltage control circuit
23 ... PLL circuit
24. Gate control circuit
31 ... Output voltage feedback
32 ... Output voltage reference
33 ... Output voltage phase reference command
34 ... Output voltage command
35 ... Gate signal
36 ... Inverter output voltage
41 ... DC capacitor
42. Switching element
43. Gate drive circuit
51 ... Voltage reference signal
52 ... Soft start signal
53 ... Multiplier
54 ... P1 control circuit
55. Carrier generation circuit
56 ... Comparator
57. Gate signal output circuit
60. Switching control circuit
61 ... Uninterruptible power supply
62 ... Power failure detection circuit
63 ... Power failure detection signal
64... Signal holding circuit
65. Switching control circuit
66 ... Manual operation circuit
71 ... Current detection circuit
72. Overcurrent detection circuit
73. Hold circuit
74: Switch circuit.

Claims (5)

A first power source for supplying power to the load;
A second power source for supplying power to the load;
Switching means for switching between power from the first power source and power from the second power source as power supplied to the load;
First voltage drop detection means for detecting a voltage drop of the first power supply;
When the voltage drop by the first voltage drop detection means is detected, the switching means performs a switching operation for switching the power supplied to the load from the power from the first power supply to the power from the second power supply. First switching operation means for outputting the first switching command;
Second voltage drop detection means for detecting a voltage drop of the second power supply;
When a voltage drop is detected by the second voltage drop detection means, the switching means performs a switching operation for switching the power supplied to the load from the power supplied by the second power supply to the power supplied by the first power supply. Second switching operation means for outputting a second switching command of:
Overcurrent detection means for detecting an overcurrent of the current flowing through the load;
When overcurrent is detected by the overcurrent detection means , the first switching operation means by the first switching operation means in a state in which power supply is continued from the first power supply or the second power supply to the load. A power supply switching device comprising: a lock unit that locks both the command and the output of the second switching command by the second switching operation unit. And a manual lock means for manually locking both the output of the first switching command by the first switching operation means and the second switching command by the second switching operation means. The power supply switching device according to 1. A first power source for supplying power to the load;
A second power source for supplying power to the load;
Switching means for switching between power from the first power source and power from the second power source as power supplied to the load;
First voltage drop detection means for detecting a voltage drop of the first power supply;
When the voltage drop by the first voltage drop detection means is detected, the switching means performs a switching operation for switching the power supplied to the load from the power from the first power supply to the power from the second power supply. First switching operation means for outputting the first switching command;
Second voltage drop detection means for detecting a voltage drop of the second power supply;
When a voltage drop is detected by the second voltage drop detection means, the switching means performs a switching operation for switching the power supplied to the load from the power supplied by the second power supply to the power supplied by the first power supply. Second switching operation means for outputting a second switching command of:
In the state where power supply is continued from the first power supply or the second power supply to the load manually, the first switching command by the first switching operation means and the second switching operation means. A power supply switching device comprising: manual locking means for locking together the outputs of the second switching command. The switching means is
A first semiconductor switch for supplying and stopping power supplied from the first power source to the load;
4. The power supply switching according to claim 1, further comprising: a second semiconductor switch that supplies and stops power supplied from the second power supply to the load. 5. apparatus. The said switching means is provided with the contactor which switches the electric power by the said 1st power supply, and the electric power by the said 2nd power supply mutually as electric power supplied to the said load. Power supply switching device.

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