JP2006141142A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply unit capable of attaining an uninterruptible power function in spite of relatively small power capacity. <P>SOLUTION: A constant-voltage and constant-frequency type uninterruptible power supply unit 12 is connected to an AC input terminal 11. A first load 8 is connected directly to an output terminal of the uninterruptible power supply unit 12. A second load 9 is connected through a variable-voltage and variable-frequency power supply unit 13. An output and a frequency of the variable-voltage and variable-frequency power supply unit 13 are increased gradually in response to a driving command of the second load 9 including a motor 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply device for supplying single-phase or multiphase AC power to a plurality of loads, and more specifically, a first load such as a communication device that requires uninterruptible power supply, and the power supply device The present invention relates to a power supply apparatus suitable for supplying electric power to a second load including an electric motor or the like for cooling one or both of the first load and the first load.

  An uninterruptible power supply for supplying electric power to a load without an uninterruptible power is, for example, as shown in Patent Documents 1, 2, 3, and 4 to be described later, a storage battery, and an AC-DC conversion for charging the storage battery. Means and DC-AC converting means for DC-AC converting the DC voltage of the storage battery.

  By the way, a plurality of loads may be connected to the uninterruptible power supply as shown in the figure. In FIG. 1, the input terminal 3 of the uninterruptible power supply 2 is connected to the AC input terminal 1 connected to the commercial AC power supply, and the output terminal 4 of the uninterruptible power supply 2 is connected to the output terminal 4 via the changeover switch 5. The 1st and 2nd alternating current output terminals 6 and 7 are connected. The changeover switch 5 bypasses the uninterruptible power supply 2 and the first and second contacts a for connecting the first and second AC output terminals 6 and 7 to the output terminal 4 of the uninterruptible power supply 2. A contact b for connecting the AC output terminals 6 and 7 to the AC input terminal 1;

  The first load 8 connected to the first AC output terminal 6 is an electronic device such as a communication device, and an instantaneous power failure is not permitted. The second load 9 connected to the second AC output terminal 7 includes, for example, an electric motor 10 and a blower fan 11 for cooling either one or both of the uninterruptible power supply 2 and the first load 8. including.

  FIG. 2 shows the positive half-wave envelope of the AC input terminal 1 of FIG. When the first load 8 is driven at time t1, a current lower than the rated current (100%) of the uninterruptible power supply 2 is supplied to the first load 8 through the uninterruptible power supply 2. Thereafter, when the temperature of the object to be cooled becomes equal to or higher than a predetermined value at time t2, the electric motor 10 is driven. When the motor 10 of the second load 9 is started at the time t2, the starting current that is larger than the rated current (100%) of the uninterruptible power supply 2 and exceeds the predetermined level (105%) of the overcurrent determination is a predetermined time. It continues to flow. As a result, the contact b of the changeover switch 5 is turned on at a time t3 after a predetermined time from the time t2, and the first and second loads 8 and 9 bypass the uninterruptible power supply 2 and are connected to the AC input terminal 1. Is done. When the current becomes lower than the predetermined level (105%) of the overcurrent determination at the time t4, the contact a of the changeover switch 5 is turned on, and the first and second loads 8 and 9 are connected via the uninterruptible power supply 2. Power is supplied.

  When the temperature of the object to be cooled becomes lower than a predetermined value, the electric motor 10 enters a non-driven state. Thereafter, when the temperature of the object to be cooled again exceeds a predetermined value, the electric motor 10 is activated, an activation current exceeding the overcurrent determination level flows, the contact b of the changeover switch 5 is turned on, and a bypass power supply state is established.

  If the power supply from the AC input terminal 1 is stopped due to a power failure during bypass power feeding, the power supply to the first and second loads 8 and 9 is interrupted. Therefore, the power supply apparatus of FIG. 1 does not have a sufficient uninterruptible power supply function. In the description of FIGS. 1 and 2, the motor 10 of the second load 9 is driven when the temperature of the object to be cooled is equal to or higher than a predetermined value. However, the motor 10 is also activated when the motor 10 is driven regardless of the temperature. Sometimes an overcurrent condition occurs and bypass power feeding occurs.

The rated current of the uninterruptible power supply 2 may be increased in order to prevent bypass power feeding at the start of the electric motor 10. However, increasing the capacity of the uninterruptible power supply inevitably causes problems such as an increase in equipment cost, an increase in installation location, and a deterioration in efficiency at light loads. This type of problem also occurs when the second load 9 is another load having the same characteristics as the electric motor 10.
Japanese Patent Laid-Open No. 12-60026 JP-A-11-178216 JP 2000-341881 A JP 2000-116137 A

  Therefore, the problem to be solved by the present invention is that it is difficult to provide a power supply device having a high uninterruptible function despite a relatively small power capacity.

  The present invention for solving the above problems includes an AC input terminal for inputting an AC voltage, a first AC output terminal for supplying AC power to the first load, and an AC power to the second load. A second AC output terminal for supplying power, and a function of being connected between the AC input terminal and the first AC output terminal and supplying power of constant voltage and constant frequency without interruption. A first power supply device, a first power supply device connected between the first power supply device and the second AC output terminal, and having a function of changing either or both of an amplitude and a frequency of an output voltage; 2 power supply devices. The present invention relates to a power supply device.

  In addition, as shown in claim 2, when the second load is supplied with a voltage having the same amplitude and frequency as the voltage of the first AC output terminal at the start-up, the second load is more than at the normal time. The load having a characteristic that a large current flows, and the second power supply device determines either or both of the amplitude and the frequency of the output voltage from a value lower than that in a steady state when the second load is started. It is desirable to have a function of gradually increasing toward the normal value.

  The power supply device of the present invention has a second power supply device having one or both of a variable frequency function and a variable voltage function in addition to the first power supply device having an uninterruptible function. The second power supply device is connected between the first power supply device and the second AC output terminal. Therefore, for example, the power supply to the second load including the AC motor or the like can be controlled by the second power supply device, and the overcurrent of the second load can be suppressed. As a result, the shared capacity for the second load of the first power supply device having the uninterruptible function can be reduced, and the cost, size, and efficiency of the first power supply device can be reduced. It becomes possible. When the second power supply device having at least one of the variable frequency function and the variable voltage function is added, the equipment cost and space for this are required. However, since an excessive current does not flow through the second power supply device, it is not necessary to design the second power supply device to withstand an excessive current such as a starting current of an AC motor. Cost and space are relatively small. That is, the cost, space, and space of the uninterruptible power supply when both the current of the first load and the excessive current of the second load are supplied by a conventional uninterruptible power supply without the second power supply, and One or two selected from the total cost, space and efficiency of the first and second power supplies according to the present invention rather than one or two selected from efficiency or all of them Etc. are all excellent.

  Next, an embodiment of the present invention will be described with reference to FIGS.

  The power supply apparatus according to the first embodiment of the present invention shown in FIG. 3 includes an AC input terminal 11, a constant voltage constant frequency uninterruptible power supply (UPS) 12 as a first power supply apparatus, and a second power supply apparatus. And a variable voltage variable frequency power supply device (VVVF) 13 that can be soft-started, and first and second AC output terminals 14 and 15. The first AC output terminal 14 is connected to a first load 8 made of an electronic device such as a communication device similar to that shown in FIG. Similarly to FIG. 1, the second AC output terminal 15 is coupled to an electric motor 10 composed of, for example, an induction motor for cooling one or both of the first load 8 and the uninterruptible power supply device 12. The second load 9 including the fan 10a is connected. In the embodiment of FIG. 3, the second load 9 is activated in response to the drive command from the drive command generating means 16. In addition, it is possible to include an object other than the electric motor 10 in the second load 9 and to connect a device in which an excessive current flows only for a predetermined period instead of the electric motor 10 as the second load 9.

  The AC input terminal 11 is connected to an AC power source such as a commercial power source (not shown) and inputs a sine wave AC voltage. The AC input terminal 11, the uninterruptible power supply 12, the variable voltage variable frequency power supply 13, the first and second AC output terminals 14 and 15 are actually in a three-phase configuration. For simplicity, a single phase configuration is shown.

  The uninterruptible power supply 12 generally called UPS has an input terminal 17 connected to the AC input terminal 11, a first AC output terminal 14, and an output terminal 18 connected to the variable voltage variable frequency power supply 13, and The first load 8 has a capacity capable of withstanding the sum of the allowable maximum current of the first load 8 and the allowable maximum current of the variable voltage variable frequency power supply device 13. In the present embodiment, since the power supply to the second load 9 is limited by the variable voltage variable frequency power supply device 13, the sum of the maximum current of the first load 8 and the maximum current of the second load 9 in FIG. Is smaller than that of FIG. Therefore, the current of the uninterruptible power supply 12 in FIG. 3 is larger than the current capacity of the conventional uninterruptible power supply 2 in the case of supplying both the current of the first load 8 in FIG. The capacity is small.

  Generally, the variable voltage variable frequency power supply device 13 called VVVF can be soft-started, and has an input terminal 19 connected to the uninterruptible power supply device 12 and an output terminal 20 connected to the second AC output terminal 15. And a function of gradually increasing the output voltage and the output frequency from zero or a low value toward the output voltage and output frequency at the rated output, that is, at the normal output in accordance with the drive command of the drive command generating means 16.

  FIG. 4 is a block diagram showing in detail the uninterruptible power supply 12 and the variable voltage variable frequency power supply 13 of FIG. The uninterruptible power supply 12 in FIG. 4 includes an AC-DC (alternating current-direct current) converter 21, a storage battery 22, and a DC-AC (direct current-alternating current) converter 23.

  The AC-DC converter 21 converts the alternating current of the input terminal 17 into direct current and charges the storage battery 22. The AC-DC converter 21 includes a rectifier circuit or an AC-DC conversion switching circuit. In this embodiment, in order to improve the power factor in the input stage of the uninterruptible power supply 12, the AC-DC converter 21 is a well-known AC-DC conversion switching having a power factor improving function as shown in Patent Document 4, for example. It consists of a circuit.

  The storage battery 22 connected to the AC-DC converter 21 functions as a DC power source for the DC-AC converter 23. In FIG. 4, the storage battery 22 is always connected to the AC-DC converter 21 and the DC-AC converter 23. However, the storage battery 22 is connected to the AC-DC converter 21 when there is no power failure, and the DC-AC converter is used when there is a power failure. 23 may be configured to be connected.

  The DC-AC converter 23 connected to the AC-DC converter 21 and the storage battery 22 is a known constant voltage frequency type inverter that converts the output DC voltage of the AC-DC converter 21 or the DC voltage of the storage battery 22 into an AC voltage. A sine wave output voltage having a constant voltage and a constant frequency is output to the output terminal 18. Since the constant voltage constant frequency type DC-AC converter 23 of FIG.

  The constant voltage constant frequency uninterruptible power supply 12 is not limited to the circuit of FIG. 4, and can be replaced with various uninterruptible power supplies as shown in Patent Documents 1 to 4.

  The variable voltage variable frequency power supply device 13 of FIG. 4 includes an AC-DC converter 24, a capacitor 25, and a DC-AC converter 26.

  The AC-DC converter 24 connected to the input terminal 19 is composed of a rectifier circuit, an AC-DC conversion switching circuit, or the like, converts the AC voltage output from the uninterruptible power supply device 12 into a DC voltage, and charges the capacitor 25. To do. Since this AC-DC converter 24 is composed of a well-known circuit in Patent Document 4 or the like, this detailed description is omitted.

  The capacitor 25 connected to the AC-DC converter 24 and the DC-AC converter 26 smoothes the output voltage of the AC-DC converter 24 and supplies it to the DC-AC converter 26.

  The DC-AC converter 26 in FIG. 4 includes a DC-AC conversion circuit 27 and its control circuit 28, as shown in detail in FIG.

  The DC-AC conversion circuit 27 includes first, second, third and fourth conversion switches Q1, Q2, Q3, Q4 made of, for example, IGBTs connected to a pair of direct current lines 29, 30, and a filter 31. Consists of. The pair of DC lines 29 and 30 are connected to both ends of the capacitor 25 of FIG. The series circuit of the first and second conversion switches Q1, Q2 and the series circuit of the third and fourth conversion switches Q3, Q4 are connected between the pair of DC lines 29, 30. The interconnection point P1 of the first and second conversion switches Q1 and Q2 and the interconnection point P2 of the third and fourth conversion switches Q3 and Q4 are connected to the pair of output terminals 20 via the filter 31. Yes. The filter 31 removes high frequency components based on on / off of the first to fourth conversion switches Q1 to Q4. When the second load 9 does not require high frequency removal, the filter 31 can be omitted. When the AC-DC converter 26 has a three-phase configuration, the fifth and sixth conversion switches are added to the pair of DC lines 29 and 30.

  The control circuit 28 of FIG. 5 is a known inverter control circuit, and has a function of forming a control signal for controlling the first to fourth conversion switches Q1 to Q4 so that the variable voltage and variable frequency can be controlled. The control circuit 28 can be composed of various known circuits capable of variable voltage and variable frequency control. In FIG. 5, the output voltage detection circuit 32, variable reference voltage source 33, error amplifier 34, and sine wave generation are shown. The circuit 35, the multiplier 36, the sawtooth generator 37, the comparator 38, the drive circuit 39, and the soft start circuit 40 are comprised.

  The output voltage detection circuit 32 is connected to the output terminal 20 and includes a known voltage detection resistor and a rectifying / smoothing circuit, and outputs an output voltage detection signal having a DC level corresponding to the amplitude of the output voltage.

  The variable reference voltage source 33 generates a reference voltage for comparison with the output voltage detection signal. For example, as shown in FIG. 6, the variable reference voltage source 33 includes a DC power source 33a, a fixed resistor 33b, and a variable resistor 33c formed of a transistor. Is done. Since the series circuit of the fixed resistor 33b and the variable resistor 33c is connected to the DC power source 33a and the output terminal 33d is connected to the interconnection point between the fixed resistor 33b and the variable resistor 33c, the resistance value of the variable resistor 33c changes. Then, the reference voltage of the output terminal 33d also changes.

The control terminal (base) of the variable resistor 33 c of the variable reference voltage source 33 is connected to the soft start circuit 40. For example, as shown in FIG. 6, the soft start circuit 40 includes a capacitor 40a, a charging power source 40b, a resistor 40c, a charging switch 40d, and a discharging switch 40e. The charging power source 40b is connected to the capacitor 40a via the charging switch 40d and the charging resistor 40c, and the discharging switch 40e is connected in parallel to the capacitor 40a. The control terminal of the charging switch 40d is connected to the start command generating means 16 in FIG. 3 via a line 16a. The control terminal of the discharge switch 40e is connected to the line 16a via a negation circuit 40f. Accordingly, when a drive command for the electric motor 10 is generated, the discharge switch 40d is turned on, and conversely, the discharge switch 40e is turned off. When the drive command for the electric motor 10 is not generated, the discharge switch 40e is turned on, and conversely, the discharge switch 40d is turned off. Accordingly, the voltage of the capacitor 40a, that is, the output voltage of the soft start circuit 40 gradually increases to a predetermined voltage simultaneously with the generation of the drive command.
Since the control terminal of the variable resistor 33c of the variable reference voltage source 33 is connected to the capacitor 40a of the soft start circuit 40, the value of the variable resistor 33c gradually decreases after the start of driving of the motor 10, and conversely, the variable reference voltage source The reference voltage 33 gradually increases toward a predetermined value.

  The error amplifier 34 of FIG. 5 has a first input terminal connected to the output voltage detection circuit 32 and a second input terminal connected to the variable reference voltage source 33, and a voltage corresponding to the difference between the two inputs. A signal having a level is output. The output of the error amplifier 34 can also be called a voltage feedback control signal. A circuit including the output voltage detection circuit 32, the variable reference voltage source 33, and the error amplifier 34 can also be called a voltage feedback control signal forming circuit.

  For example, as shown in FIG. 6, the sine wave generation circuit 35 includes an oscillator 35a, an address circuit 35b, and a memory 35c storing sine wave data, and generates a sine wave signal. A soft start circuit 40 is connected to the sine wave generation circuit 35 in order to gradually increase the output frequency of the output terminal 20 when the electric motor 10 is started. That is, the oscillator 35 a of the sine wave generation circuit 35 is connected to the capacitor 40 a of the soft start circuit 40. When the voltage of the capacitor 40a is gradually increased at the time of starting the electric motor 10, the output frequency of the oscillator 35a is gradually increased, the reading speed of the sine wave data stored in the memory 35c is gradually increased, and is transmitted from the output terminal 33d. The frequency of the generated sine wave gradually increases.

  One input terminal of the multiplier 36 in FIG. 5 is connected to the sine wave generation circuit 35, and the other input terminal is connected to the error amplifier 34. Thus, multiplier 36 multiplies the sinusoidal voltage by the voltage feedback signal to form a signal. The output signal of the multiplier 36 includes AC voltage waveform information and output voltage adjustment information.

  The sawtooth wave generator 37 generates a sawtooth voltage, that is, a carrier waveform at a repetition frequency of, for example, 20 to 100 kHz, which is sufficiently higher than the frequency (for example, 0 to 60 Hz) of the sine wave generated from the sine wave generation circuit 35.

  One input terminal of the comparator 38 is connected to the multiplier 36, and the other input terminal is connected to the sawtooth generator 37. Therefore, the comparator 38 compares the sawtooth voltage with the output signal of the multiplier 36 and outputs a DC-AC conversion control signal composed of a known PWM signal.

  The drive circuit 39 connected to the comparator 38 forms control signals for the first to fourth conversion switches Q1 to Q4 by a well-known method based on the PWM signal obtained from the comparator 38. 4 is supplied to the control terminals of the conversion switches Q1 to Q4.

  FIG. 7A shows the positive half-wave envelope or envelope of the output current of the uninterruptible power supply 12 of FIG. 3 as a ratio based on the rated current, and FIG. FIG. 7C shows a positive half-wave envelope (envelope) of the output voltage V1, and FIG. 7C shows a positive half-wave envelope (envelope) of the output voltage V2 of the variable voltage variable frequency power supply device 13. (D) shows the output frequency f2 of the variable voltage variable frequency power supply 13.

  When the uninterruptible power supply 12 is activated at time t0 in FIG. 7, a constant output voltage V1 is obtained at the output terminal 18 as shown in FIG. This output voltage V1 is an AC voltage having a constant frequency. When the first load 8 is activated at time t1, a current having a substantially constant first value I1 flows as shown in FIG. The first load 8 of this embodiment is a communication device or the like, and the current change is smaller than that of the second load 9. Accordingly, when a constant voltage V1 having a constant frequency is supplied to the first load 8, no current (for example, 105%) that greatly exceeds the rated current does not flow.

  When a drive command for the second load 9 is generated from the drive command generating means 16 at time t2 in FIG. 7, the drive of the second load 9 is started and the output voltage V2 and the output frequency of the variable voltage variable frequency power supply device 13 are started. An operation of gradually increasing f2 from a value (for example, zero) lower than the rated output voltage Vc and the rated output frequency fc toward the rated output voltage Vc and the rated output frequency fc occurs. As shown in FIGS. 7C and 7D, when the output voltage V2 and the output frequency f2 of the variable voltage variable frequency power supply device 13 are gradually increased, for example, the current of the second load 9 including the electric motor 10 composed of an induction motor and the like. The input and output currents of the variable voltage variable frequency power supply device 13 gradually increase. Since the current of the output terminal 18 of the uninterruptible power supply 12 is the sum of the currents of the first and second loads 8 and 9, it gradually increases during the period t2 to t3 in FIG. The value is almost constant I2. Since the electric motor 10 is included in the second load 9, the voltage and frequency of the electric motor 10 are controlled so as to gradually increase by the variable voltage variable frequency power supply device 13 during the activation period t 2 to t 3. Excessive starting current exceeding% does not flow. For this reason, the uninterruptible power supply 12 can continue the power supply to the first and second loads 8 and 9.

  When the electric motor 10 of the second load 9 is driven depending on the temperature of an object to be cooled such as the uninterruptible power supply 12 and the first and second loads 8 and 9, for example, after time t3 in FIG. When the temperature of the object to be cooled decreases, the output of the drive command generation means 16 becomes zero, the electric motor 10 stops, and the output voltage V2 and the output frequency f2 of the variable voltage variable frequency power supply device 13 become zero. Thereafter, when the temperature of the object to be cooled reaches a value that requires cooling, a drive command is generated from the drive command generating means 16, and the same operation as after t2 in FIG.

As is apparent from the above, this embodiment has the following effects.
(1) Since the voltage and frequency supplied to the second load 9 when the second load 9 is started up are gradually increased by the variable voltage variable frequency power supply device 13, an overcurrent is prevented. For this reason, an excessive current does not flow through the uninterruptible power supply 12 when the second load 9 is activated. Therefore, the allowable maximum current value of the uninterruptible power supply 12 can be set to a low value, and the cost, size, and efficiency of the uninterruptible power supply 12 can be reduced. In addition, although the cost and space based on the variable voltage variable frequency power supply device 13 increase and the efficiency decreases, an excessive start-up current does not flow in the variable voltage variable frequency power supply device 13. And the increase in space is not so great, and the decrease in efficiency is not so great. Therefore, the uninterruptible power supply 12 in FIG. 3 is compared with the conventional system in which the variable voltage variable frequency power supply 13 is not provided and power is supplied to the first and second loads 8 and 9 by the uninterruptible power supply 12 alone. And the variable voltage variable frequency power supply device 13 are superior in one, two or all of cost, space and efficiency.
(2) It has a higher uninterruptible power supply function for the first and second loads 8 and 9 than the conventional bypass power supply system.
(3) Since the voltage and frequency of the electric motor 10 gradually increase from a low value toward the rating at the time of starting, the noise level at the time of starting the electric motor 10 can be lowered.
(4) Since it has the variable voltage variable frequency power supply device 13 and the AC-DC converter 21 has a well-known power factor improvement function, the rated capacity and consumption of the uninterruptible power supply device 12 can be combined by these combinations. Electric power can be greatly reduced.

  The power supply device according to the second embodiment has the same configuration as that of the first embodiment except for a control circuit 28a of FIG. 8 in which the control circuit 28 of the first embodiment is modified. Therefore, in the description of the second embodiment, reference is made to FIGS. 3 to 7 for portions other than the control circuit 28a. Further, in the control circuit 28a of FIG. 8, parts that are substantially the same as those of the control circuit 28 of FIG.

  8 is replaced with the output detection circuit 32, the variable reference voltage source 33, the error amplifier 34, the sine wave generation circuit 35, and the multiplier 36, the output voltage detection circuit 32a and the sine wave generation circuit. 35 ', a subtractor 36a and a proportional integration (IP) circuit 36b are provided, and the others are configured in the same manner as in FIG.

The output voltage detection circuit 32a in FIG. 8 is configured to detect the AC voltage at the output terminal 20 without rectifying and smoothing. The sine wave generation circuit 35 ′ is a variable voltage variable frequency sine wave generation circuit whose amplitude and frequency change in response to the output of the soft start circuit 40. Accordingly, the amplitude and frequency of the output of the sine wave generation circuit 35 'gradually increase during the period from t2 to t3 in FIG. The subtractor 36a outputs a signal indicating the difference between the output of the sine wave generation circuit 35 'and the output of the output voltage detection circuit 32a. The proportional integration circuit 36b includes a subtractor 36.
A signal obtained by proportionally integrating the output of a is sent to the comparator 38. The comparator 38 compares the output of the sawtooth generator 37 and the output of the proportional integration circuit 36b to form a PWM signal.

  The DC-AC conversion circuit 27 in FIG. 5 can also be subjected to variable voltage variable frequency control by the control circuit 28a in FIG. Therefore, the same effect as in the first embodiment can be obtained also in the second embodiment.

The present invention is not limited to the first and second embodiments described above. For example, the following modifications are possible.
(1) As shown by a dotted line in FIG. 5, the voltage level adjustment circuit 41 is connected to the output stage of the output voltage detection circuit 32, the output stage of the error amplifier 34, the output stage of the sine wave generation circuit 35, or the multiplier 36. It can be provided at the output stage or the output stage of the sawtooth generator 37 and controlled by the output of the soft start circuit 40 to control the output voltage V2 as shown in FIG. In this case, the variable reference voltage source 33 in FIG. 5 is modified to a fixed reference voltage source. Similarly, as indicated by a dotted line in FIG. 8, a voltage level adjustment circuit 41 is provided at the output stage of the proportional integration circuit 36b or the output stage of the sawtooth wave generation circuit 37, and this is controlled by the output of the soft start circuit 40. As shown in FIG. 7C, the output voltage V2 can be controlled. In this case, the sine wave generating circuit 35 'is modified so that only the frequency is changed by the output of the soft start circuit 40.
(2) Of course, the DC-AC conversion circuit 27 may be controlled by a control circuit other than the control circuit 28 of FIG. 5 and the control circuit 28a of FIG.
(3) The first to fourth conversion switches of the DC-AC conversion circuit 27 of FIG. 5 can be configured by other semiconductor switches such as FETs and transistors other than IGBTs.
(4) Although the DC-AC conversion circuit 27 is shown as a single phase in FIG. 5, it can be configured as a three-phase DC-AC conversion circuit.
(5) A switch Sb is connected between the AC input terminal 11 and the output stage of the uninterruptible power supply 12 as shown by a dotted line in FIG. 3, and the first and second loads 8, 9 are connected from the uninterruptible power supply 12. When it becomes impossible to supply power to the first and second loads 8 and 9 directly from the AC power source (not shown) connected to the AC input terminal 11 via the switch Sb. Can be supplied.
(6) The drive command generation means 16 can be incorporated in the second load 9.
(7) Instead of the variable output variable frequency power supply device 13, a variable output power supply device or a variable frequency power supply device is provided, and only one of the voltage and frequency supplied to the second load 9 is controlled to generate the starting current. It may be reduced.

It is a block diagram which shows the conventional power supply voltage apparatus. It is a figure which shows the electric current change in the alternating current input terminal of FIG. 1 with the envelope (envelope) of a positive half wave. It is a block diagram which shows the power supply device of Example 1 of this invention. It is a block diagram which shows in detail the uninterruptible power supply and variable voltage variable frequency power supply of FIG. It is a circuit diagram which shows the DC-AC converter of FIG. 4 in detail. FIG. 6 is a circuit diagram illustrating in detail the variable reference voltage source, the sine wave generation circuit, and the soft start circuit of FIG. 5. It is a figure which shows the state of each part of FIG. 3 with progress of time. FIG. 6 is a block diagram illustrating a control circuit according to a second embodiment.

Explanation of symbols

11 AC input terminal 12 Uninterruptible power supply 13 Variable voltage variable frequency power supply 14 First AC output terminal 15 Second AC output terminal

Claims (2)

AC input terminal for inputting AC voltage;
A first AC output terminal for supplying AC power to the first load;
A second AC output terminal for supplying AC power to the second load;
A first power supply device connected between the AC input terminal and the first AC output terminal and having a function of supplying power of constant voltage and constant frequency without interruption;
A second power supply device connected between the first power supply device and the second AC output terminal and having a function of changing either or both of an amplitude and a frequency of the output voltage. A power supply device characterized by that. The second load is a load having such a characteristic that a current larger than that in a steady state flows when a voltage having the same amplitude and frequency as the voltage of the first AC output terminal is supplied at the time of starting. ,
The second power supply device has a function of gradually increasing one or both of the amplitude and frequency of the output voltage from a value lower than the steady state to a steady state value when starting the second load. The power supply device according to claim 1, further comprising:

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