Single-phase power converter and electromagnetic vibrator equipped with same

Abstract

To achieve a compact and long-life configuration without using a capacitor in a single-phase power converter that supplies single-phase power to a coil from an AC power supply.SOLUTION: A single-phase power converter 1 is a single-phase power converter that supplies single-phase power to a coil 3 from an AC power supply 2. The single-phase power converter 1 has: a switching circuit 10 that has a plurality of switching elements SW1-SW4 electrically connected with the AC power supply 2 and the coil 3 to supply a current flowing in one direction and changing periodically to the coil 3 from the AC power supply 2; and a drive control unit 20 that controls the drive of the plurality of switching elements SW1-SW4. The drive control unit 20 controls the drive of the plurality of switching elements SW1-SW4 based on the tendency of change of a current command to be input and the difference between the current command and the current flowing in the coil 3, thereby operating the switching circuit 10 in any one of a power running operation, a regenerative operation, and a reflux operation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a single-phase power conversion device that supplies single-phase power from an AC power source to a coil, and an electromagnetic vibration machine equipped with the same.

Background Art

[0002] A single-phase power conversion device that supplies single-phase power from an AC power source to a coil is known. As such a single-phase power conversion device, for example, a single-phase inverter circuit for an electromagnetic vibration machine disclosed in Patent Document 1 is known.

[0003] The single-phase inverter circuit for electromagnetic vibration has an inverse conversion circuit in which two switching means and two diodes are bridge-connected. The input side of the inverse conversion circuit is connected to a DC power source, and the output side of the inverse conversion circuit is connected to the input terminal of the exciting coil for the electromagnetic vibration machine. With such a circuit configuration, the single-phase inverter circuit for electromagnetic vibration constitutes a single-phase inverter that intermittently supplies current only in one direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the single-phase inverter circuit for electromagnetic vibration disclosed in Patent Document 1, a DC power source is used. The DC power source is configured to supply DC power to a load by, for example, a rectifier circuit having an AC power source and a capacitor. Further, in a circuit that supplies power to a coil, which is an inductive load, like the single-phase inverter circuit for electromagnetic vibration disclosed in Patent Document 1, a power running operation of supplying power to the coil and a regeneration operation of returning power from the coil to the power source side are repeated.

[0006] When supplying power to an inductor load coil using a rectifier circuit having a capacitor as described above, the current flowing through the capacitor fluctuates due to the power running operation and the regeneration operation as described above, so the voltage of the rectifier circuit fluctuates. In order to suppress this voltage fluctuation within an appropriate range, it is necessary to increase the capacitance of the capacitor, and an electrolytic capacitor is generally used as the capacitor that satisfies such requirements.

[0007] The capacitor generates heat due to current fluctuations caused by the power running operation and the regeneration operation of the single-phase inverter circuit. When an electrolytic capacitor is used as the capacitor as described above, it deteriorates due to the current fluctuations and self-heating due to the ambient temperature, so its lifespan may be shorter than that of other components.

[0008] In this way, the capacitor of the rectifier circuit increases the size of the entire power conversion device and determines the lifespan of the power conversion device.

[0009] An object of the present invention is to achieve a compact and long-life configuration without using a capacitor in a single-phase power conversion device that supplies single-phase power from an AC power source to a coil.

Means for Solving the Problem

[0010] A single-phase power conversion device according to an embodiment of the present invention is a single-phase power conversion device that supplies single-phase power from an AC power supply to a coil. This single-phase power conversion device has a switching circuit electrically connected to the AC power supply and the coil so as to supply a current that flows in one direction from the AC power supply to the coil and periodically changes, and a drive control unit that controls the driving of the plurality of switching elements. The drive control unit controls the driving of the plurality of switching elements based on the change tendency of the input current command and the difference between the current command and the current flowing through the coil, thereby operating the switching circuit in any one of a power running operation, a regeneration operation, and a reflux operation (first configuration).

[0011] The switching circuit can supply a current that flows in one direction from the AC power supply to the coil and periodically changes, and based on the change tendency of the current command and the difference between the current command and the current flowing through the coil, the switching circuit can be operated in any one of a power running operation, a regeneration operation, and a reflux operation with respect to the coil that is an inductive load. Therefore, without using a rectifier circuit having a capacitor, a current that flows in one direction from the AC power supply to the coil and periodically changes can be supplied, and a power running operation, a regeneration operation, and a reflux operation can be realized in a circuit including the coil.

[0012] Therefore, in a single-phase power conversion device that supplies single-phase power from an AC power supply to a coil, since it is not necessary to use a capacitor, a compact and long-life configuration can be realized.

[0013] In the first configuration, when the current command is increasing and the current flowing through the coil is smaller than the current command, the drive control unit controls the driving of the plurality of switching elements so as to cause the switching circuit to perform a power running operation. When the current command is decreasing and the current flowing through the coil is larger than the current command, the drive control unit controls the driving of the plurality of switching elements so as to cause the switching circuit to perform a regeneration operation. When the current command is increasing and the current flowing through the coil is larger than the current command, or when the current command is decreasing and the current flowing through the coil is smaller than the current command, the drive control unit controls the driving of the plurality of switching elements so as to cause the switching circuit to perform a reflux operation (second configuration).

[0014] Accordingly, when the current command is increasing and the current flowing through the coil is smaller than the current command, power can be supplied from the AC power supply to the coil by causing the switching circuit to perform a power running operation. On the other hand, when the current command is decreasing and the current flowing through the coil is larger than the current command, power can be returned from the coil to the AC power supply by causing the switching circuit to perform a regeneration operation. Also, when the current command is increasing and the current flowing through the coil is larger than the current command, or when the current command is decreasing and the current flowing through the coil is smaller than the current command, current can be refluxed in the switching circuit by causing the switching circuit to perform a reflux operation. Thereby, while reducing the number of switchings of the switching elements constituting the switching circuit, the current flowing through the coil can be made closer to the current command.

[0015] As described above, with the above-described configuration, the operation of the drive control unit in the first configuration can be realized. Therefore, with the above-described configuration, in a single-phase power conversion device that supplies single-phase power from an AC power supply to a coil, it is not necessary to use a capacitor, and thus a compact and long-life configuration can be realized.

[0016] In the first or second configuration, the plurality of switching elements each include two pairs of switching elements electrically connected in series. The two pairs of switching elements are electrically connected in parallel to the coil, and the midpoints thereof are each electrically connected to the AC power supply (third configuration).

[0017] With the above configuration, the configuration of the switching circuit in the first configuration can be realized. Therefore, with the above configuration, in a single-phase power conversion device that supplies single-phase power from an AC power supply to a coil, there is no need to use a capacitor, so a compact and long-life configuration can be realized.

[0018] In the third configuration, when the switching circuit is operating in a power running operation or a regeneration operation, the drive control unit determines, according to the polarity of the voltage output from the AC power supply, the switching element to be turned on among the pair of switching elements in the two pairs of switching elements (fourth configuration).

[0019] Thereby, according to the polarity of the voltage output from the AC power supply, one of the pair of switching elements in the two pairs of switching elements can be turned on, and the switching circuit can be caused to perform a power running operation or a regeneration operation.

[0020] An electromagnetic vibrator according to an embodiment of the present invention includes a single-phase power conversion device having any one of the first to fourth configurations, a coil to which a current flowing in one direction and periodically changing is supplied by the single-phase power conversion device, and an elastic deformation portion that generates vibration by elastically deforming due to energization of the coil (fifth configuration).

[0021] Thereby, a compact and long-life electromagnetic vibrator can be realized.

Advantages of the Invention

[0022] A single-phase power conversion device according to an embodiment of the present invention includes a switching circuit having a plurality of switching elements electrically connected to the AC power source and the coil so as to supply a current that flows in one direction to the coil from the AC power source and periodically changes, and a drive control unit that controls the driving of the plurality of switching elements. The drive control unit controls the driving of the plurality of switching elements based on the change tendency of the input current command and the difference between the current command and the current flowing through the coil, thereby operating the switching circuit in any one of a power running operation, a regeneration operation, and a reflux operation.

[0023] Thereby, without using a rectifier circuit having a capacitor, a current that flows in one direction to the coil from the AC power source and periodically changes is supplied, and a power running operation, a regeneration operation, and a reflux operation can be realized in a circuit including the coil. Therefore, in a single-phase power conversion device that supplies single-phase power from the AC power source to the coil, it is not necessary to use a capacitor, so a compact and long-life configuration can be realized.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and their descriptions will not be repeated.

[0026] (Configuration of Single-Phase Power Conversion Device) FIG. 1 is a diagram showing a schematic configuration of a single-phase power conversion device 1 according to an embodiment of the present invention. This single-phase power conversion device 1 supplies a current that flows in one direction and changes periodically from an AC power supply 2 to a coil 3. That is, the single-phase power conversion device 1 causes a current to flow through the coil 3 in one direction and periodically changes the current flowing through the coil 3 (see FIG. 10(d) described later). The coil 3 is, for example, a coil for an electromagnetic vibrator used in an electromagnetic vibrator. The configuration of the electromagnetic vibrator will be described later.

[0027] The single-phase power conversion device 1 includes a switching circuit 10 and a drive control unit 20. The switching circuit 10 includes a plurality of switching elements SW1 to SW4 and diodes D1 to D4.

[0028] Of the multiple switching elements SW1 to SW4, the switching elements SW1 and SW2 are electrically connected in series, and therefore form a first switching leg 11. The switching elements SW1 and SW2 are a pair of switching elements in the present invention.

[0029] Of the multiple switching elements SW1 to SW4, the switching elements SW3 and SW4 are electrically connected in series. Therefore, the switching elements SW3 and SW4 form a second switching leg 12. The switching elements SW3 and SW4 are a pair of switching elements in the present invention.

[0030] As described above, the switching circuit 10 has the first switching leg 11 and the second switching leg 12. That is, the switching circuit 10 has two pairs of switching elements.

[0031] The first switching leg 11 and the second switching leg 12 are electrically connected in parallel to the coil 3. Specifically, one end of the first switching leg 11 and the second switching leg 12 is connected to the other end of the coil 3, and the other end of the first switching leg 11 and the second switching leg 12 is connected to one end of the coil 3.

[0032] The midpoint of the switching elements SW1 and SW2 in the first switching leg 11 and the midpoint of the switching elements SW3 and SW4 in the second switching leg 12 are electrically connected to the AC power supply 2. Specifically, the midpoint of the switching elements SW1 and SW2 in the first switching leg 11 is electrically connected to one terminal of the AC power supply 2, and the midpoint of the switching elements SW3 and SW4 in the second switching leg 12 is electrically connected to the other terminal of the AC power supply 2.

[0033] Diodes D1 to D4 are electrically connected in series to switching elements SW1 to SW4 between the switching elements SW1 to SW4 and coil 3. Specifically, diode D1 is provided between switching element SW1 and coil 3 so that current flows from coil 3 to switching element SW1. Diode D2 is provided between switching element SW2 and coil 3 so that current flows from switching element SW2 to coil 3. Diode D3 is provided between switching element SW3 and coil 3 so that current flows from coil 3 to switching element SW3. Diode D4 is provided between switching element SW4 and coil 3 so that current flows from switching element SW4 to coil 3.

[0034] By providing diodes D1 to D4 in the switching circuit 10 as described above, it is possible to prevent current from flowing in the reverse direction through switching elements SW1 to SW4. Therefore, switching elements with a relatively low breakdown voltage can be used for switching elements SW1 to SW4. Moreover, in order to ensure the flow of current in the switching circuit 10, even when all of the switching elements SW1 to SW4 are turned on during the switching operation of the switching elements SW1 to SW4, diodes D1 to D4 can prevent current from flowing in the reverse direction through switching elements SW1 to SW4.

[0035] The drive control unit 20 controls the drive of switching elements SW1 to SW4 according to the input current command. The drive control unit 20 outputs a drive signal for turning on the switching elements SW1 to SW4, for example, to the switching elements SW1 to SW4 based on the change tendency of the input current command and the difference between the current command and the current flowing through coil 3. The change tendency of the current command is, for example, an increasing tendency when the amount of change per unit time of the current command is increasing, and a decreasing tendency when the amount of change per unit time of the current command is decreasing.

[0036] Specifically, when the current command is increasing and the current flowing through coil 3 is smaller than the current command, the drive control unit 20 controls the driving of the switching elements SW1 to SW4 so as to cause the switching circuit 10 to perform a power running operation described later. Further, when the current command is decreasing and the current flowing through coil 3 is larger than the current command, the drive control unit 20 controls the driving of the switching elements SW1 to SW4 so as to cause the switching circuit 10 to perform a regeneration operation described later. Further, when the current command is increasing and the current flowing through coil 3 is larger than the current command, or when the current command is decreasing and the current flowing through coil 3 is smaller than the current command, the drive control unit 20 controls the driving of the switching elements SW1 to SW4 so as to cause the switching circuit 10 to perform a reflux operation described later.

[0037] Although details will be described later, the power running operation is an operation in which the switching circuit 10 supplies power from the AC power supply 2 to the coil 3 by driving the switching elements SW1 to SW4. The regeneration operation is an operation in which the switching circuit 10 returns power from the coil 3 to the AC power supply 2 by driving the switching elements SW1 to SW4. The reflux operation is an operation in which a current is refluxed in a circuit constituted by the switching circuit 10 and the coil 3 by driving the switching elements SW1 to SW4.

[0038] In the switching circuit 10 having the above configuration, by driving the switching elements SW1 to SW4 by the drive control unit 20, it is possible to supply a current that flows in one direction and changes periodically from the AC power supply 2 to the coil 3. Moreover, by driving the switching elements SW1 to SW4, the switching circuit 10 can be operated in any of a power running operation, a regeneration operation, and a reflux operation. Each operation of the switching circuit 10 will be described below.

[0039] (Power running operation) First, the power running operation of the switching circuit 10 will be described with reference to FIGS. 2 and 3. As described above, the power running operation of the switching circuit 10 is an operation performed when the current command is on an increasing trend and the current flowing through the coil 3 is smaller than the current command. In the power running operation of the switching circuit 10, according to the polarity of the voltage output from the AC power supply 2, the switching elements SW2 and SW3 are in the on state, or the switching elements SW1 and SW4 are in the on state.

[0040] In the following description, the polarity of the voltage such that current flows from the AC power supply 2 to the first switching leg 11 is defined as positive, and the polarity of the voltage such that current flows from the AC power supply 2 to the second switching leg 12 is defined as negative. FIG. 2 shows the current flow when the polarity of the voltage output from the AC power supply 2 is positive and the switching elements SW2 and SW3 are in the on state. FIG. 3 shows the current flow when the polarity of the voltage output from the AC power supply 2 is negative and the switching elements SW1 and SW4 are in the on state.

[0041] In the power running operation, when the polarity of the voltage output from the AC power supply 2 is positive and the switching elements SW2 and SW3 are in the on state, the switching elements SW1 and SW4 are in the off state. In this case, as shown by the solid arrows in FIG. 2, current flows through the circuit from the AC power supply 2 in the order of the switching element SW2, the diode D2, the coil 3, the diode D3, and the switching element SW3.

[0042] On the other hand, in the power running operation, when the polarity of the voltage output from the AC power supply 2 is negative and the switching elements SW1 and SW4 are in the on state, the switching elements SW2 and SW3 are in the off state. In this case, as shown by the solid line in FIG. 3, current flows through the circuit from the AC power supply 2 in the order of the switching element SW4, the diode D4, the coil 3, the diode D1, and the switching element SW1.

[0043] In either case of FIGS. 2 and 3, the switching circuit 10 can supply a periodic current in one direction from the AC power supply 2 to the coil 3. That is, power is supplied from the AC power supply 2 to the coil 3.

[0044] (Regenerative operation) The regenerative operation of the switching circuit 10 will be described with reference to FIGS. 4 and 5. As described above, the regenerative operation of the switching circuit 10 is an operation performed when the current command is decreasing and the current flowing through the coil 3 is greater than the current command. In the regenerative operation of the switching circuit 10, according to the polarity of the voltage output from the AC power supply 2, the switching element SW1 and the switching element SW4 are in the on state, or the switching element SW2 and the switching element SW3 are in the on state. FIG. 4 shows the current flow when the polarity of the voltage output from the AC power supply 2 is positive and the switching elements SW1 and SW4 are in the on state. FIG. 5 shows the current flow when the polarity of the voltage output from the AC power supply 2 is negative and the switching elements SW2 and SW3 are in the on state.

[0045] In the regenerative operation, when the polarity of the voltage output from the AC power supply 2 is positive and the switching elements SW1 and SW4 are in the on state, the switching elements SW2 and SW3 are in the off state. In this case, since the current continues to flow in one direction through the inductive load coil 3, as shown by the solid arrows in FIG. 4, the current flows through the circuit in the order of the coil 3, the diode D1, the switching element SW1, the AC power supply 2, the switching element SW4, and the diode D4. That is, the current flows through the circuit from the coil 3 toward the AC power supply 2.

[0046] On the other hand, in the regenerative operation, when the polarity of the voltage output from the AC power supply 2 is negative and the switching elements SW2 and SW3 are in the on state, the switching elements SW1 and SW4 are in the off state. In this case, since the current continues to flow in one direction through the inductive load coil 3, as shown by the solid arrows in FIG. 5, the current flows through the circuit in the order of the coil 3, the diode D3, the switching element SW3, the AC power supply 2, the switching element SW2, and the diode D2. That is, the current flows through the circuit from the coil 3 toward the AC power supply 2.

[0047] In either case of FIGS. 4 and 5, the switching circuit 10 can cause a current to flow from the coil 3 to the AC power supply 2. That is, power is returned from the coil 3 to the AC power supply 2.

[0048] (Regeneration operation) The regeneration operation of the switching circuit 10 will be described with reference to FIGS. 6 and 7. As described above, the regeneration operation of the switching circuit 10 is performed when the current command is increasing and the current flowing through the coil 3 is greater than the current command, or when the current command is decreasing and the current flowing through the coil 3 is less than the current command. In the regeneration operation of the switching circuit 10, regardless of the polarity of the voltage output from the AC power supply 2, the switching element SW1 and the switching element SW2 are in the on state, or the switching element SW3 and the switching element SW4 are in the on state. The current flow when the switching elements SW1 and SW2 are in the on state is shown in FIG. 6. The current flow when the switching elements SW3 and SW4 are in the on state is shown in FIG. 7.

[0049] In the regeneration operation, when the switching elements SW1 and SW2 are in the on state, the switching elements SW3 and SW4 are in the off state. In this case, since a current continues to flow in one direction through the inductive load coil 3, as shown by the solid arrows in FIG. 6, the current flows through the circuit from the coil 3 in the order of the diode D1, the switching element SW1, the switching element SW2, and the diode D2.

[0050] On the other hand, in the regeneration operation, when the switching elements SW3 and SW4 are in the on state, the switching elements SW1 and SW2 are in the off state. In this case, since a current continues to flow in one direction through the inductive load coil 3, as shown by the solid arrows in FIG. 7, the current flows through the circuit from the coil 3 in the order of the diode D3, the switching element SW3, the switching element SW4, and the diode D4.

[0051] Next, an example of the current flowing through the coil 3 when the switching circuit 10 performs each of the above operations will be described. FIG. 8 is a diagram showing an example of the waveform of the current flowing through the coil 3 when the switching circuit 10 performs each of the above operations. For the sake of explanation, the waveform of the alternating current output from the AC power supply 2 is also shown by a thin solid line in FIG. 8.

[0052] When the switching circuit 10 performs each of the above operations, as the current waveform flowing through the coil 3, a current waveform (thick solid line) close to the sinusoidal current command (broken line) as shown in FIG. 8 can be obtained.

[0053] FIG. 9 is a diagram showing a list of the switching patterns of the switching elements SW1 to SW4 at each timing in FIG. 8. In FIG. 9, the switching patterns in I to VIII are the switching patterns at each of the time points I to VIII shown in FIG. 8.

[0054] Also, in FIG. 9, A indicates the tendency of change of the current command, which is "+" when the current command is increasing and "-" when the current command is decreasing. In FIG. 9, B indicates the polarity of the difference between the current command and the current flowing through the coil 3, which is "+" when the current flowing through the coil 3 is smaller than the current command and "-" when the current flowing through the coil 3 is larger than the current command. In FIG. 9, C indicates the polarity of the voltage output from the AC power supply 2, which is "+" when the polarity of the voltage is positive and "-" when the polarity of the voltage is negative.

[0055] For example, as shown in I and III of FIG. 9, when the current command is increasing (A is +) and the current flowing through coil 3 is smaller than the current command (B is +), the switching circuit 10 performs a power running operation by the drive control of the switching elements SW1 to SW4 by the drive control unit 20. That is, the switching element SW2 and the switching element SW3 of the switching circuit 10 are turned on, or the switching element SW1 and the switching element SW4 are turned on. Which of the switching element SW2 and the switching element SW3, or the switching element SW1 and the switching element SW4 is turned on is determined according to the polarity (+, -) of the voltage output from the AC power supply 2. That is, the drive control unit 20 determines the switching elements to be driven in each of the two pairs of switching elements (the first switching leg 11, the second switching leg 12) according to the polarity of the voltage output from the AC power supply 2.

[0056] By the switching circuit 10 performing the power running operation as described above, power is supplied from the AC power supply 2 to the coil 3. The current flowing from the AC power supply 2 to the coil 3 is a current that flows in one direction and changes periodically, as shown in FIG. 10(d) described later.

[0057] Also, as shown in VI and VIII of FIG. 9, when the current command is decreasing (A is -) and the current flowing through coil 3 is greater than the current command (B is -), the switching circuit 10 performs a regeneration operation by the drive control of switching elements SW1 to SW4 by the drive control unit 20. That is, the switching element SW1 and the switching element SW4 of the switching circuit 10 are turned on, or the switching element SW2 and the switching element SW3 are turned on. Which of the switching element SW1 and the switching element SW4, or the switching element SW2 and the switching element SW3 is turned on is determined according to the polarity (+, -) of the voltage output from the AC power supply 2. That is, the drive control unit 20 determines the switching elements to be driven in each of the two pairs of switching elements (the first switching leg 11, the second switching leg 12) according to the polarity of the voltage output from the AC power supply 2.

[0058] As described above, when the switching circuit 10 performs the regeneration operation, power is returned from the coil 3 to the AC power supply 2. Also in this case, the current flowing through the coil 3 is a current that flows in one direction and changes periodically.

[0059] Also, as shown in II and IV of FIG. 9, when the current command is increasing (A is +) and the current flowing through coil 3 is greater than the current command (B is -), or as shown in V and VII of FIG. 9, when the current command is decreasing (A is -) and the current flowing through coil 3 is smaller than the current command (B is +), the switching circuit 10 performs a reflux operation by the drive control of switching elements SW1 to SW4 by the drive control unit 20. That is, the switching element SW1 and the switching element SW2 of the switching circuit 10 are turned on, or the switching element SW3 and the switching element SW4 are turned on. For example, the switching element SW1 and the switching element SW4 may be turned on, or the switching element SW2 and the switching element SW3 may be turned on so that the switching operation of the switching elements SW1 to SW4 is minimized.

[0060] As described above, when the switching circuit 10 performs the reflux operation, without performing the power running operation or the regeneration operation, the current command changes and the difference between the current command and the current flowing through the coil 3 becomes smaller. Therefore, while reducing the number of switching operations of the switching elements SW1 to SW4, the current flowing through the coil 3 can be made closer to the current command. Thereby, the loss generated in the single-phase power conversion device 1 can be reduced.

[0061] The single-phase power conversion device 1 of the present embodiment is a single-phase power conversion device that supplies single-phase power from the AC power supply 2 to the coil 3. The single-phase power conversion device 1 includes a switching circuit 𝟏𝟎 having a plurality of switching elements SW1 to SW4 electrically connected to the AC power supply 2 and the coil 3 so as to supply a current that flows in one direction from the AC power supply 2 to the coil 3 and changes periodically, and a drive control unit 20 that controls the driving of the plurality of switching elements SW1 to SW4. The drive control unit 20 controls the driving of the plurality of switching elements SW1 to SW4 based on the change tendency of the input current command and the difference between the current command and the current flowing through the coil 3, thereby operating the switching circuit 10 in any one of a power running operation, a regeneration operation, and a reflux operation.

[0062] The switching circuit 10 of the present embodiment can supply a current that flows in one direction from the AC power supply 2 to the coil 3 and changes periodically, and based on the change tendency of the current command and the difference between the current command and the current flowing through the coil 3, the switching circuit 10 can be operated in any one of a power running operation, a regeneration operation, and a reflux operation with respect to the coil 3 which is an inductive load. Therefore, without using a rectifier circuit having a capacitor, a current that flows in one direction from the AC power supply 2 to the coil 3 and changes periodically can be supplied, and a power running operation, a regeneration operation, and a reflux operation can be realized in a circuit including the coil 3.

[0063] Therefore, in the single-phase power conversion device 1 that supplies single-phase power from the AC power supply 2 to the coil 3, since there is no need to use a capacitor, a compact and long-life configuration can be realized.

[0064] Moreover, in the single-phase power conversion device 1 of the present embodiment, since a capacitor is not required, it is not necessary to consider the inrush current to the capacitor when the power switch is turned on. Therefore, in the single-phase power conversion device 1 of the present embodiment, an inrush current prevention circuit is not required.

[0065] Also, in the present embodiment, when the current command is increasing and the current flowing through the coil 3 is smaller than the current command, the drive control unit 20 controls the drive of the switching elements SW1 to SW4 so as to make the switching circuit 10 perform a power running operation. When the current command is decreasing and the current flowing through the coil 3 is larger than the current command, the drive control unit 20 controls the drive of the switching elements SW1 to SW4 so as to make the switching circuit 10 perform a regeneration operation. When the current command is increasing and the current flowing through the coil 3 is larger than the current command, or when the current command is decreasing and the current flowing through the coil 3 is smaller than the current command, the drive control unit 20 controls the drive of the switching elements SW1 to SW4 so as to make the switching circuit 10 perform a reflux operation.

[0066] Thereby, when the current command is increasing and the current flowing through the coil 3 is smaller than the current command, power can be supplied from the AC power supply 2 to the coil 3 by making the switching circuit 10 perform a power running operation. On the other hand, when the current command is decreasing and the current flowing through the coil 3 is larger than the current command, power can be returned from the coil 3 to the AC power supply 2 by making the switching circuit 10 perform a regeneration operation. Also, when the current command is increasing and the current flowing through the coil 3 is larger than the current command, or when the current command is decreasing and the current flowing through the coil 3 is smaller than the current command, the current can be refluxed by the switching circuit 10 by making the switching circuit 10 perform a reflux operation. Thereby, while reducing the number of switching operations of the switching elements SW1 to SW4 constituting the switching circuit 10, the current flowing through the coil 3 can be made closer to the current command.

[0067] Also, in this embodiment, when the switching circuit 10 is operating in the power running operation or the regeneration operation, the drive control unit 20 determines, according to the polarity of the voltage output from the AC power supply 2, which one of the pair of switching elements in the two sets of switching elements is to be turned on.

[0068] Accordingly, according to the polarity of the voltage output from the AC power supply 2, one of the pair of switching elements in the two sets of switching elements can be turned on, and the switching circuit 10 can be made to perform the power running operation or the regeneration operation.

[0069] FIG. 10 is a diagram showing the relationships such as the current command, the output current of the AC power supply 2, the current flowing through the coil 3, and the switching patterns of the switching elements SW1 to SW4 when the single-phase power conversion device 1 having the above-described configuration is being driven. In FIG. 10, (a) is the current command, (b) is the change tendency of the current command, (c) is the output current of the AC power supply 2, (d) is the current flowing through the coil 3, (e) is the difference between the current command and the current flowing through the coil 3, and (f) to (i) are the switching patterns of the switching elements SW1 to SW4.

[0070] As shown in FIG. 10, in the single-phase power conversion device 1, the switching elements SW1 to SW4 perform intermittent switching operations. Therefore, compared with the sinusoidal PWM method on the voltage control side, the number of switching operations of the switching elements SW1 to SW4 can be reduced. Therefore, the loss of the single-phase power conversion device 1 can be reduced.

[0071] (Electromagnetic vibrator) FIG. 11 is a schematic diagram showing a schematic configuration of an example of the electromagnetic vibrator 100 including the single-phase power conversion device 1 and the coil 3 having the above-described configuration. The electromagnetic vibrator 100 may be any device as long as it has a configuration that can vibrate by utilizing the magnetic attraction force generated in the coil 3, such as a parts feeder, a linear feeder, a bowl feeder, a vibrating conveyor, or the like.

[0072] As shown in FIG. 11, the electromagnetic vibrator 100 includes a single-phase power conversion device 1, a coil 3, an elastic deformation portion 101, a movable core 102, a trough 103, and a base portion 104.

[0073] The electromagnetic vibrator 100 supplies, by means of the single-phase power conversion device 1, a current that flows in one direction and periodically changes from the AC power supply 2 to the coil 3. The coil 3 generates a magnetic attraction force by the current supplied from the AC power supply 2 via the single-phase power conversion device 1.

[0074] The elastic deformation portion 101 connects the base portion 104 and the trough 103. In the present embodiment, the electromagnetic vibrator 100 has a pair of elastic deformation portions 101. The elastic deformation portion 101 is a plate-like member that can be elastically deformed. The elastic deformation portion 101 is, for example, a metal leaf spring extending in one direction. Note that the elastic deformation portion 101 has, for example, a resonance frequency that coincides with the driving frequency of the coil 3 (the frequency at which the magnetic attraction force is generated).

[0075] The movable core 102 is connected to the trough 103. The movable core 102 is located in the vicinity of the coil 3 and is attracted to the coil 3 by the magnetic attraction force generated in the coil.

[0076] With the above-described configuration, when a current flows in one direction and periodically changes in the coil 3, the magnetic attraction force generated in the coil 3 changes, and the movable core 102 moves in a direction approaching and a direction away from the coil 3. That is, when the current flowing through the coil 3 increases, the magnetic attraction force generated in the coil 3 increases and the movable core 102 is attracted to the coil 3. On the other hand, when the current flowing through the coil 3 decreases, the magnetic attraction force generated in the coil 3 decreases and the movable core 102 moves away from the coil 3.

[0077] As a result, the trough 103 to which the movable core 102 is connected also moves in a direction approaching and a direction away from the coil 3. Since the trough 103 is elastically supported by the base portion 104 by a pair of elastic deformation portions 101, vibrations occur in the vertical and horizontal directions.

[0078] In this embodiment, the electromagnetic vibrator 100 includes a single-phase power conversion device 1, a coil 3 to which a periodic current in one direction is supplied by the single-phase power conversion device 1, and an elastic deformation portion 101 that generates vibration by undergoing elastic deformation when current is applied to the coil 3.

[0079] As described above, the single-phase power conversion device 1 does not require a capacitor. Since the electromagnetic vibrator 100 has the single-phase power conversion device 1 that does not require a capacitor, a compact and long-life electromagnetic vibrator 100 can be realized.

[0080] [Other Embodiments] Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for implementing the present invention. Therefore, without being limited to the above-described embodiments, it is possible to appropriately modify and implement the above-described embodiments within the scope not departing from the gist thereof.

[0081] In the above embodiment, the switching circuit 10 has diodes D1 to D4 electrically connected in series to the switching elements SW1 to SW4 between the switching elements SW1 to SW4 and the coil 3. However, the switching circuit may have a diode electrically connected in series to a part of the switching elements between the part of the switching elements and the coil. Further, the switching circuit may not have a diode.

[0082] In the above embodiment, the diodes D1 to D4 are located between the switching elements SW1 to SW4 and the coil 3 in the switching circuit 10. However, the switching element may be located between the diode and the coil.

[0083] In the above embodiment, the plurality of switching elements SW1 to SW4 include two pairs of switching elements that are electrically connected in series. The two pairs of switching elements are electrically connected in parallel to the coil 3, and the midpoints thereof are electrically connected to the AC power supply 2. However, as long as the switching circuit can supply a current that flows in one direction from the AC power supply to the coil and periodically changes, and has a configuration that can operate in any of the power running operation, regeneration operation, and reflux operation based on the change tendency of the input current command and the difference between the current command and the current flowing through the coil, other configurations may be used.

[0084] In the above embodiment, the single-phase power conversion device 1 is used in the electromagnetic vibrator 100. However, as long as the single-phase power conversion device has a configuration that supplies a current that flows in one direction and periodically changes to the coil, it may be applied to configurations other than the electromagnetic vibrator.

Industrial Applicability

[0085] The present invention can be used in a single-phase power conversion device that supplies single-phase power from an AC power supply to a coil and an electromagnetic vibrator including the same.

Explanation of Signs

[0086] 1 Single-phase power conversion device 2 AC power supply 3 Coil 10 Switching circuit 11 First switching leg 12 Second switching leg 20 Drive control unit 100 Electromagnetic vibrator 101 Elastic deformation part 102 Movable core 103 Trough 104 Base part SW1, SW2, SW3, SW4 Switching elements D1, D2, D3, D4 Diodes

Claims

1. In a single-phase power conversion device that supplies single-phase power from an AC power source to a coil, a switching circuit having a plurality of switching elements electrically connected to the AC power source and the coil so as to supply a current that flows in one direction and periodically changes from the AC power source to the coil; a drive control unit that controls the driving of the plurality of switching elements; characterized by comprising: the drive control unit controls the driving of the plurality of switching elements based on the change tendency of the input current command and the difference between the current command and the current flowing through the coil, thereby operating the switching circuit in any one of a power running operation, a regeneration operation, and a reflux operation. Single-phase power conversion device.

2. In the single-phase power conversion device according to claim 1, the drive control unit: when the current command is increasing and the current flowing through the coil is smaller than the current command, controls the driving of the plurality of switching elements so as to operate the switching circuit in a power running operation; when the current command is decreasing and the current flowing through the coil is larger than the current command, controls the driving of the plurality of switching elements so as to operate the switching circuit in a regeneration operation; when the current command is increasing and the current flowing through the coil is larger than the current command, or when the current command is decreasing and the current flowing through the coil is smaller than the current command, controls the driving of the plurality of switching elements so as to operate the switching circuit in a reflux operation. Single-phase power conversion device.

3. In the single-phase power conversion device according to claim 1 or 2, the plurality of switching elements include two sets of a pair of switching elements electrically connected in series to each other, the two sets of a pair of switching elements are electrically connected in parallel to the coil, and the midpoints thereof are electrically connected to the AC power source respectively. Single-phase power conversion device.

4. In the single-phase power conversion device according to claim 3, when the switching circuit is operating in a power running operation or a regeneration operation, the drive control unit determines, according to the polarity of the voltage output from the AC power source, the switching element to be turned on among the pair of switching elements in the two sets of a pair of switching elements respectively. Single-phase power conversion device.

5. A single-phase power conversion device according to any one of claims 1 to 4, the coil to which a periodic current is supplied in one direction by the single-phase power conversion device, an elastic deformation part that generates vibration by causing elastic deformation due to energization of the coil, having, an electromagnetic vibrator.

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