JP2015192498A - Ac regulated power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC regulated power unit capable of suppressing a power loss within a voltage variation range without requiring load voltage compensation.SOLUTION: An AC regulated power unit 100 is configured to apply an AC voltage that is applied from a commercial power source 1, after compensating the AC voltage within a voltage allowable range of a load. The AC regulated power unit 100 includes: a transformer 2 for transforming the AC voltage; a first switch 3 for changing over whether the AC voltage is applied to the transformer 2; a second switch 4 for switching the voltage to be applied to the load 7 between the voltage transformed by the transformer 2 and the AC voltage from the commercial power source 1; voltage detection means 5 for detecting a voltage of the commercial power source 1; and control means 6 for controlling the first switch 3 and the second switch 4 in accordance with the voltage of the commercial power source 1.

Description

  The present invention relates to an AC stabilized power supply device.

  As an AC stabilized power supply device that compensates for voltage fluctuations of the AC power supply and stabilizes the voltage applied to the load, for example, when the voltage applied from the AC power supply exceeds the allowable voltage range of the load, the compensation voltage is injected. A technique is disclosed in which the compensation voltage is not injected when the voltage is within the allowable voltage range (for example, Patent Document 1). As a result, it is said that power supply loss from the AC power source to the load can be reduced in a voltage fluctuation range that does not require load voltage compensation.

JP 2003-264882 A

  In the above prior art, the injection transformer is always present in the power supply path from the AC power source to the load. For this reason, an excitation current flows through the injection transformer even in a voltage fluctuation range that does not require load voltage compensation, which is inefficient.

  The present invention has been made in view of the above, and an object of the present invention is to obtain an AC stabilized power supply device that can suppress power loss in a voltage fluctuation range that does not require load voltage compensation.

  In order to solve the above-described problems and achieve the object, an AC stabilized power supply device according to a first aspect of the present invention compensates an AC voltage applied from a commercial power source within a voltage allowable range of a load, and An AC stabilized power supply device to be applied to a load, the transformer for transforming the AC voltage, a first switch for switching presence / absence of application of the AC voltage to the transformer, and the voltage applied to the load to the transformer A second switch for switching to one of the voltage transformed by the voltage and the AC voltage, voltage detection means for detecting the AC voltage, and the first switch and the second switch according to the AC voltage. And a control means for controlling the switch.

  The AC stabilized power supply according to the second aspect of the present invention is the AC stabilized power supply according to the first aspect of the present invention, wherein the control means has the AC voltage within the allowable voltage range. In this case, the second switch is controlled to apply the AC voltage to the load, and the first switch is controlled to stop the application of the AC voltage to the transformer. To do.

  Moreover, the AC stabilized power supply according to the third aspect of the present invention is the AC stabilized power supply according to the second aspect of the present invention, wherein the control means has the AC voltage within the voltage range. When the first switch is detected, the first switch is controlled after the second switch is controlled.

  Further, the AC stabilized power supply according to the fourth aspect of the present invention is the AC stabilized power supply according to the first aspect of the present invention, wherein the control means has the AC voltage at least outside the voltage allowable range. In some cases, controlling the first switch to apply the AC voltage to the transformer, and controlling the second switch to apply the voltage transformed by the transformer to the load. Features.

  The AC stabilized power supply according to the fifth aspect of the present invention is the AC stabilized power supply according to the fourth aspect of the present invention, wherein the control means is such that the AC voltage is outside the voltage range. When the first switch is detected, the second switch is controlled after the first switch is controlled.

  According to the present invention, it is possible to suppress power loss in a voltage fluctuation range that does not require load voltage compensation.

FIG. 1 is a diagram of a configuration example of the AC stabilized power supply device according to the first embodiment. FIG. 2 is a diagram illustrating an example of a state of each unit corresponding to the voltage range of the commercial power supply of the stabilized power supply according to the first embodiment. FIG. 3 is a diagram illustrating an example in which the first switch and the second switch of the AC stabilized power supply device according to the first embodiment are configured by semiconductor bidirectional switches. FIG. 4 is a diagram of a configuration example of the AC stabilized power supply device according to the second embodiment. FIG. 5 is a diagram illustrating an example of a state of each unit corresponding to the voltage range of the commercial power supply of the stabilized power supply according to the second embodiment.

  Embodiments of an AC stabilized power supply device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a diagram illustrating a configuration example of the AC stabilized power supply device 100 according to the first embodiment. As shown in FIG. 1, the AC stabilized power supply device 100 according to the first embodiment has an input terminal (L1, N1 terminal) connected to a commercial power source 1 and an output terminal (L2, N2 terminal) connected to a load 7, The AC voltage applied from the commercial power source 1 is compensated within the allowable voltage range of the load 7 and applied to the load 7.

  The AC stabilized power supply device 100 includes a transformer 2 that transforms an AC voltage applied from a commercial power source 1, a first switch 3 that switches whether or not an AC voltage is applied to the transformer 2, and an applied voltage to a load 7. A second switch 4 for switching to one of a voltage transformed by the transformer 2 and an AC voltage, a voltage detection means 5, and a control means 6 are provided.

  The voltage detection means 5 is connected between the L1-N1 terminals and detects the voltage of the commercial power source 1. Further, the control means 6 controls the first switch 3 and the second switch 4 according to the voltage of the commercial power source 1 output from the voltage detection means 5.

  In the present embodiment, the transformer 2 is a single-winding transformer in which a part of one winding is shared by the primary side and the secondary side. The transformer 2 includes a power input terminal P connected to an intermediate point of the winding, a ground terminal G connected to one end of the winding, and a plurality of transformer output terminals Sb connected to each point of the winding. Sc, Sd, and Se are provided. The power input terminal P is connected to the L1 terminal, and the ground terminal G is connected to one end of the first switch 3.

  The other end of the first switch 3 is connected to the N1 and N2 terminals. When the first switch 3 is closed and controlled by the control means 6, an AC voltage is applied from the commercial power source 1 to the transformer 2.

  The second switch 4 has a contact a connected to the L1 terminal and each contact b, c, d, e provided corresponding to the plurality of transformer output terminals Sb, Sc, Sd, Se of the transformer 2. ing. When the second switch 4 is switched by the control means 6, either the AC voltage applied from the commercial power source 1 or the voltage transformed by the transformer 2 is applied to the load 7.

  Next, the operation of the AC stabilized power supply apparatus 100 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 2 is a diagram illustrating an example of a state of each unit corresponding to the voltage range of the commercial power supply 1 of the stabilized power supply apparatus 100 according to the first embodiment. In the present embodiment, the allowable voltage range of the load 7 is 90 V or more and 110 V or less. 2 shows an example in which the voltage compensation range by the AC stabilized power supply apparatus 100 is 75V ≦ X <125V, and the voltage of the commercial power supply 1 detected by the voltage detection means 5 (detected voltage value). X) is in the range of 95V ≦ X <105V, state A, in the case of 75V ≦ X <85V, in state B, in the case of 85V ≦ X <95V, in state C, 105V ≦ X <115V The state D is in the state D, and the state E is in the range 115V ≦ X <125V.

  As shown in FIG. 2, in the present embodiment, in the state A, that is, when the voltage (detected voltage value X) of the commercial power source 1 detected by the voltage detecting means 5 is in the range of 95V ≦ X <105V. The control means 6 controls to open the first switch 3 and select the contact a of the second switch 4. As a result, the AC voltage from the commercial power source 1 is not applied to the transformer 2, and the AC voltage from the commercial power source 1 is directly applied to the load 7. For this reason, in this state A, the exciting current does not flow through the transformer 2, and power loss due to the transformer 2 can be eliminated.

  In the state B, that is, when the voltage of the commercial power supply 1 (detected voltage value X) detected by the voltage detecting means 5 is in the range of 75V ≦ X <85V, the control means 6 is connected to the first switch 3. Is controlled to be closed, and the contact b of the second switch 4 is selected. Thereby, the AC voltage from the commercial power source 1 is applied to the transformer 2, and the voltage transformed by the transformer 2 is applied to the load 7. At this time, by setting the transformation ratio at the transformation output terminal Sb to 1.25, the voltage applied to the load 7 is in the range of 95.83V to 104.17V.

  In the state C, that is, when the voltage (detected voltage value X) of the commercial power source 1 detected by the voltage detecting means 5 is in the range of 85V ≦ X <95V, the control means 6 is connected to the first switch 3. Is controlled to be closed, and the contact c of the second switch 4 is selected. Thereby, the AC voltage from the commercial power source 1 is applied to the transformer 2, and the voltage transformed by the transformer 2 is applied to the load 7. At this time, by setting the transformation ratio at the transformation output terminal Sc to 1.11, the voltage applied to the load 7 is in the range of 95.45V to 104.55V.

  In the state D, that is, when the voltage (detected voltage value X) of the commercial power source 1 detected by the voltage detecting means 5 is in the range of 105V ≦ X <115V, the control means 6 is connected to the first switch 3. Is controlled to be closed and the contact d of the second switch 4 is selected. Thereby, the AC voltage from the commercial power source 1 is applied to the transformer 2, and the voltage transformed by the transformer 2 is applied to the load 7. At this time, by setting the transformation ratio at the transformation output terminal Sd to 0.91, the voltage applied to the load 7 falls within the range of 94.44V to 105.56V.

  In the state E, that is, when the voltage (detected voltage value X) of the commercial power supply 1 detected by the voltage detecting means 5 is in the range of 115V ≦ X <125V, the control means 6 is connected to the first switch 3. Is controlled so as to select the contact e of the second switch 4. Thereby, the AC voltage from the commercial power source 1 is applied to the transformer 2, and the voltage transformed by the transformer 2 is applied to the load 7. At this time, the voltage applied to the load 7 is within the range of 93.75V to 106.25V by setting the transformation ratio at the transformation output terminal Se to 0.83.

  By controlling in this way, the voltage range applied to the load 7 can be compensated within the voltage allowable range of the load 7 (here, 90 V or more and 110 V or less).

  In the present embodiment, when the state C or the state D is shifted to the state A, the control means 6 controls the second switch 4 to supply the load 7 from the commercial power source 1. After the application of the AC voltage is started, the first switch 3 is controlled to be opened, and the application of the AC voltage from the commercial power source 1 to the transformer 2 is stopped. Further, when shifting from the state A to the state C or the state D, the control means 6 controls the first switch 3 to be closed and starts applying the AC voltage from the commercial power source 1 to the transformer 2. After that, the second switch 4 is controlled to start application of the voltage transformed by the transformer 2 to the load 7.

  By controlling in this way, it is possible to prevent the application of voltage to the load 7 from being stopped.

  Even when the above-described control is performed, between the respective contacts a, b, c, d, e of the second switch 4 in the transition between the states A, B, C, D, E. Therefore, a non-connection time in which no contact is made occurs. For this reason, although it is an extremely short time, it is equivalent to the state where the application of the voltage to the load 7 is stopped, which may cause the load 7 to stop or malfunction. On the other hand, if the non-connection time is short, continuous operation is possible by the capacity component of the load 7. Accordingly, the non-connection time that occurs when the second switch 4 is switched needs to be shorter than the time during which the continuous operation of the load 7 is impossible.

  FIG. 3 is a diagram illustrating an example in which the first switch 3 and the second switch 4 of the AC stabilized power supply apparatus 100 according to the first embodiment are configured by semiconductor bidirectional switches.

  As shown in FIG. 3, when the first switch 3 and the second switch 4 are constituted by semiconductor bidirectional switches using, for example, an IGBT or the like, the switching speed of the first switch 3 and the second switch 4 is increased. Can be

  For example, when the second switch 4 is formed of a semiconductor bidirectional switch, the above-described disconnection time can be reduced to the time required for turning on / off the semiconductor bidirectional switch.

  Further, for example, when the first switch 3 is constituted by a semiconductor bidirectional switch, the time required for the transition from the state C or the state D to the state A and the transition from the state A to the state C or the state D is shortened. be able to.

  In the example illustrated in FIG. 2, the example in which the voltage compensation range by the AC stabilized power supply apparatus 100 is in the range of 75 V ≦ X <125 V has been described. However, the voltage compensation range may be set to a wider range. In this case, the number of transformer output terminals of the transformer 2 (the number of contacts of the second switch) may be increased. Alternatively, the voltage compensation range can be set to a narrower range. In the example illustrated in FIG. 2, the example in which the range of the detected voltage value X in each state is 10 V has been described. However, the range of the detected voltage value X in each state is further narrowed, and the compensated voltage range is May be narrower, or may be set wider within a range not exceeding the allowable voltage range of the load 7. It goes without saying that the present invention is not limited by these voltage compensation ranges, the number of transformer output terminals (number of contacts of the second switch) of the transformer 2, or the range of the detected voltage value X.

  Further, when the AC voltage applied from the commercial power supply 1 exceeds the voltage compensation range (75V ≦ X <125V in the example shown in FIG. 2) by the AC stabilized power supply apparatus 100, or the temperature of the transformer 2 is detected. If the temperature of the transformer 2 is controlled by providing temperature detecting means for performing the above operation and the rated temperature of the transformer 2 is exceeded, for example, the power supply path from the commercial power source 1 may be disconnected by a switch means (not shown). . With such a configuration, the transformer 2 and the load 7 can be protected, and the transformer 2 having a low rated capacity can be used.

  As described above, according to the first embodiment, the first switch for switching the application of the AC voltage from the commercial power supply to the autotransformer and the voltage applied to the load are transformed by the autotransformer. Since the second switch for switching to one of the voltage and the AC voltage applied from the commercial power source is provided, when the commercial power source voltage is within the allowable voltage range of the load, the commercial power source is connected to the load. When the AC voltage is applied and the application of the AC voltage from the commercial power supply to the autotransformer is stopped, and the commercial power supply voltage is outside the above voltage range, the AC voltage from the commercial power supply is supplied to the autotransformer. And a voltage transformed by a single-winding transformer to the load to suppress power loss in the voltage fluctuation range that does not require load voltage compensation, while reducing the voltage range applied to the load. It can be compensated for within the allowable voltage range.

  In addition, when it is detected that the voltage of the commercial power source is within the voltage range described above, the second switch is controlled to start application of the AC voltage from the commercial power source to the load. Is controlled to open, and the application of the AC voltage from the commercial power source to the autotransformer is stopped. In addition, when it is detected that the voltage of the commercial power supply is outside the voltage range described above, the first switch is closed and the application of the AC voltage from the commercial power supply to the single-winding transformer is started. Then, the control of the second switch is performed, and the application of the voltage transformed by the single transformer is started with respect to the load. Thereby, it can prevent that the application of the voltage to load stops.

  Further, by configuring one or both of the first switch and the second switch with a semiconductor bidirectional switch, the time required for switching the voltage applied to the load can be shortened.

(Embodiment 2)
FIG. 4 is a diagram of a configuration example of the AC stabilized power supply device 100a according to the second embodiment. In the first embodiment, the configuration using a single-winding transformer as the transformer 2 has been described. However, in this embodiment, an example in which a multi-winding transformer having a primary winding and a secondary winding is used as the transformer 2a. Will be described. In addition, the same code | symbol is attached | subjected to the component which is the same as that of Embodiment 1, or equivalent, and the detailed description is abbreviate | omitted.

  As shown in FIG. 4, the AC stabilized power supply device 100a according to the second embodiment has a primary winding and a secondary winding as a transformer 2a instead of the single-winding transformer described in the first embodiment. The configuration uses a compound winding transformer. The transformer 2a is provided with a power supply input terminal P connected to one end of the primary winding, a ground terminal G1 connected to the other end of the primary winding, and a secondary winding facing the ground terminal G1. A plurality of transformer output terminals Sb, Sc, Sd, Se connected to each point of the ground terminal G2 and the secondary winding are provided. The power input terminal P is connected to the L1 terminal, the ground terminal G1 is connected to the contact f of the first switch 3a, and the ground terminal G2 is connected to the contact g and the N2 terminal of the first switch 3a.

  The first switch 3a is a three-way switch, and is configured to selectively connect the f contact and the contact g connected to the N2 terminal to the N1 terminal. When the first switch 3a selects the contact point f by the control means 6, an AC voltage is applied from the commercial power source 1 to the primary winding of the transformer 2a.

  Next, the operation of the AC stabilized power supply apparatus 100a according to the present embodiment will be described with reference to FIGS. FIG. 5 is a diagram illustrating an example of the state of each unit corresponding to the voltage range of the commercial power supply 1 of the stabilized power supply apparatus 100a according to the second embodiment. In FIG. 5, the allowable voltage range of the load 7, the voltage compensation range by the AC stabilized power supply device 100a, and the range of the detected voltage value X in each state A, B, C, D, E are the same as in the first embodiment. is there.

  As shown in FIG. 5, in the present embodiment, in the state A, that is, when the voltage of the commercial power source 1 (detected voltage value X) detected by the voltage detecting means 5 is in the range of 95V ≦ X <105V. The control means 6 controls to select the contact point g of the first switch 3a, and controls to select the contact point a of the second switch 4. Thereby, the AC voltage from the commercial power source 1 is not applied to the primary winding of the transformer 2a, and the AC voltage from the commercial power source 1 is directly applied to the load 7. For this reason, in this state A, the exciting current does not flow through the transformer 2a, and power loss due to the transformer 2a can be eliminated.

  In the state B, that is, when the voltage of the commercial power source 1 (detected voltage value X) detected by the voltage detecting means 5 is in the range of 75V ≦ X <85V, the control means 6 is connected to the first switch 3a. And control to select the contact b of the second switch 4. As a result, the AC voltage from the commercial power source 1 is applied to the primary winding of the transformer 2a, and the voltage transformed by the transformer 2a is applied to the load 7. At this time, by setting the transformation ratio at the transformation output terminal Sb to 1.25, the voltage applied to the load 7 is in the range of 95.83V to 104.17V.

  In the state C, that is, when the voltage (detected voltage value X) of the commercial power supply 1 detected by the voltage detecting means 5 is in the range of 85V ≦ X <95V, the control means 6 controls the first switch 3a. And control to select the contact c of the second switch 4. As a result, the AC voltage from the commercial power source 1 is applied to the primary winding of the transformer 2a, and the voltage transformed by the transformer 2 is applied to the load 7. At this time, by setting the transformation ratio at the transformation output terminal Sc to 1.11, the voltage applied to the load 7 is in the range of 95.45V to 104.55V.

  In the state D, that is, when the voltage of the commercial power supply 1 (detected voltage value X) detected by the voltage detecting means 5 is in the range of 105V ≦ X <115V, the control means 6 is connected to the first switch 3a. And control to select the contact d of the second switch 4. As a result, the AC voltage from the commercial power source 1 is applied to the primary winding of the transformer 2a, and the voltage transformed by the transformer 2a is applied to the load 7. At this time, by setting the transformation ratio at the transformation output terminal Sd to 0.91, the voltage applied to the load 7 falls within the range of 94.44V to 105.56V.

  In the state E, that is, when the voltage (detection voltage value X) of the commercial power supply 1 detected by the voltage detection means 5 is in the range of 115V ≦ X <125V, the control means 6 controls the first switch 3a. And control to select the contact e of the second switch 4. As a result, the AC voltage from the commercial power source 1 is applied to the primary winding of the transformer 2a, and the voltage transformed by the transformer 2a is applied to the load 7. At this time, the voltage applied to the load 7 is within the range of 93.75V to 106.25V by setting the transformation ratio at the transformation output terminal Se to 0.83.

  By controlling in this way, the applied voltage range to the load 7 can be compensated within the allowable voltage range of the load 7 (here, 90 V or more and 110 V or less) as in the first embodiment.

  Also in the present embodiment, as in the first embodiment, when the state C or the state D is shifted to the state A, the control unit 6 controls the second switch 4 to load the load 7. On the other hand, after the application of the AC voltage from the commercial power source 1 is started, the first switch 3a is controlled to stop the application of the AC voltage from the commercial power source 1 to the transformer 2a. Further, when shifting from the state A to the state C or the state D, the control means 6 controls the first switch 3a to start application of the AC voltage from the commercial power source 1 to the transformer 2a. Later, the second switch 4 is controlled to start applying the voltage transformed by the transformer 2a to the load 7.

  By controlling in this way, it is possible to prevent the application of voltage to the load 7 from being stopped as in the first embodiment.

  Furthermore, although not shown here, as in the first embodiment, when the first switch 3a and the second switch 4 are configured by a semiconductor bidirectional switch using, for example, an IGBT or the like, the first switch 3a and the second switch 4 are configured. The switching speed of the second switch 4 can be increased, and the time required for switching the voltage applied to the load can be shortened.

  Similarly to the first embodiment, the voltage compensation range may be set wider or narrower, and the number of transformer output terminals (number of contacts of the second switch) provided in the secondary winding of the transformer 2a may be set. May increase. Further, the range of the detected voltage value X in each state may be narrowed to make the compensated voltage range narrower, or may be set wider within a range not exceeding the allowable voltage range of the load 7. . It goes without saying that the present invention is not limited by the voltage compensation range, the number of transformer output terminals (number of contacts of the second switch), the range of the detected voltage value X, or the like.

  Similarly to the first embodiment, when the AC voltage applied from the commercial power source 1 exceeds the voltage compensation range by the AC stabilized power supply device 100a, or a temperature detecting means for detecting the temperature of the transformer 2a is provided. If the temperature of the transformer 2a is managed and the rated temperature of the transformer 2a is exceeded, the power supply path from the commercial power supply 1 may be cut off by a switch means (not shown), for example. With such a configuration, the transformer 2a and the load 7 can be protected, and a transformer 2a having a low rated capacity can be used.

  As described above, according to the second embodiment, the first switch for switching the application of the AC voltage from the commercial power supply to the compound transformer and the voltage applied to the load are transformed by the compound transformer. Since the second switch for switching to one of the voltage and the AC voltage from the commercial power supply is provided, if the commercial power supply voltage is within a voltage range narrower than the allowable voltage range of the load, While applying the AC voltage from the power source and stopping the application of the AC voltage from the commercial power source to the compound transformer, if the voltage of the commercial power source is outside the above voltage range, As in the first embodiment, the power loss in the voltage fluctuation range that does not require load voltage compensation is suppressed by applying the AC voltage and the voltage transformed by the double winding transformer to the load. One, the range of applied voltages to the load can be compensated within the allowable voltage range of the load.

  In addition, when it is detected that the voltage of the commercial power source is within the voltage range described above, the second switch is controlled to start application of the AC voltage from the commercial power source to the load. Is controlled to stop the application of the AC voltage from the commercial power supply to the compound transformer. In addition, when it is detected that the voltage of the commercial power source is outside the above-described voltage range, the first switch is controlled to start application of the AC voltage from the commercial power source to the compound transformer. Control of the second switch is performed, and application of the voltage transformed by the compound transformer is started with respect to the load. Thereby, it is possible to prevent the application of the voltage to the load from being stopped as in the first embodiment.

  Further, by configuring one or both of the first switch and the second switch with a semiconductor bidirectional switch, the time required for switching the voltage applied to the load can be shortened as in the first embodiment. Can do.

  In the above-described embodiment, an example in which the commercial power source is a single-phase AC power source is shown. However, even when the commercial power source is a three-phase AC power source, the first switch and the second switch are provided for each phase. It can be applied by providing a switch.

  The configurations described in the above embodiments are examples of the configurations of the present invention, and can be combined with other known techniques, and a part of the configurations is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

  As described above, the AC stabilized power supply device according to the present invention compensates for load voltage in a configuration in which an AC voltage applied from a commercial power supply is compensated within the allowable voltage range of the load using a transformer and applied to the load. This is useful for suppressing power loss in a voltage fluctuation range that is not required.

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2,2a Transformer 3,3a 1st switch 4 2nd switch 5 Voltage detection means 6 Control means 7 Load 100,100a AC stabilized power supply device

Claims (5)

An AC stabilized power supply device that compensates an AC voltage applied from a commercial power source within a voltage allowable range of the load and applies the AC voltage to the load,
A transformer for transforming the AC voltage;
A first switch for switching presence / absence of application of the AC voltage to the transformer;
A second switch for switching a voltage applied to the load to one of the voltage transformed by the transformer and the AC voltage;
Voltage detecting means for detecting the AC voltage;
Control means for controlling the first switch and the second switch according to the AC voltage;
An AC stabilized power supply device comprising:   The control means controls the second switch so as to apply the AC voltage to the load when the AC voltage is within the allowable voltage range, and applies the AC voltage to the transformer. The AC stabilized power supply device according to claim 1, wherein the first switch is controlled to stop.   3. The control unit according to claim 2, wherein when the AC voltage is detected to be within the voltage range, the control unit controls the first switch after controlling the second switch. 4. AC stabilized power supply.   The control means controls the first switch to apply the AC voltage to the transformer when the AC voltage is at least outside the allowable voltage range, and is transformed to the load by the transformer. The AC stabilized power supply device according to claim 1, wherein the second switch is controlled to apply a voltage.   5. The control unit according to claim 4, wherein when the AC voltage is detected to be outside the voltage range, the control unit controls the second switch after controlling the first switch. 6. AC stabilized power supply.

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