Motor control device, motor, generator control device, generator, and wind generator

Abstract

This control device for a motor, a generator or the like is provided with: current supply lines (42a, 42b, 42c) for supplying currents having a phase difference to each coil (32 (32a)) of a motor or a generator provided with a magnet; and a switching unit (44) that switches between a disconnected state and a connected state between the current supply lines.

Description

Technical Field

[0001] The invention relates to a control device for an electric motor, a control device for an electric motor and a generator, a generator and a wind power generator. Background Art

[0002] As a technology related to a motor and a motor control device for controlling the motor, a technology for demagnetizing or magnetizing a magnet of a motor has been proposed. For example, Patent Document 1 describes changing the speed torque characteristic of a motor by demagnetizing or magnetizing a magnet of a motor.

[0003] However, in order to demagnetize or magnetize the magnets of the motor, a strong magnetic force must be generated around the magnets at least temporarily. Therefore, for example, a larger current than when the motor is driven to rotate must flow through the coil to generate a magnetic field that demagnetizes or magnetizes the magnets.

[0004] Therefore, the inverter for driving the motor needs to be enlarged, and efforts need to be made to reduce the size. In addition, there is also a demand for demagnetizing or magnetizing magnets in generators such as wind power generators.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-72046 Summary of the invention

[0008] Problems to be solved by the invention

[0009] An object of the present invention is to provide a motor control device, a motor and a generator control device, a generator, and a wind turbine generator that can be used to easily demagnetize or magnetize magnets of a motor or a generator.

[0010] Technical solutions to solve problems

[0011] In order to achieve the above object, one aspect of the present invention provides a control device for a motor, which has:

[0012] a current supply line for supplying currents having phase differences to each coil of the motor having the magnet; and

[0013] A switching unit switches between a non-connected state and a connected state between the current supply lines.

[0014] While the current supply lines are kept disconnected by the switching unit, AC currents having phase differences are supplied to the motor, and the motor rotates during normal operation. When the magnets provided in the rotor or stator of the motor are demagnetized or magnetized, the current supply lines are connected by the switching unit.

[0015] If the current supply lines with a phase difference are connected, a short-circuit current flows between the lines, thereby increasing the amplitude of the current. Therefore, a current larger than that in normal operation (for example, more than twice) can be passed through the coil of the motor without changing the output of the inverter or the like. As a result, a magnetic field higher than that applied in normal operation (for example, more than 1.8 times) is applied to the magnet of the motor, making it easy to demagnetize or magnetize the magnet.

[0016] Preferably, the switching unit has a switching element for switching the current supply lines between a non-connected state and a connected state. By configuring the switching element between the current supply lines, the current supply lines with different phases can be switched from a non-connected state to a connected state, or from a connected state to a non-connected state.

[0017] The control device may also have a capacitor (at least one) connected in series with the switching element. In addition, the capacitor connected in series with the switching element does not necessarily have to be arranged inside the switching unit, that is, between the current supply lines, but may be arranged in the current supply line itself, or may be arranged inside the motor or inside the inverter. However, when the current supply lines are disconnected from each other by the switching element, from the viewpoint of stopping the function of the capacitor, the capacitor is preferably arranged in series with the switching element between the current supply lines.

[0018] By providing a capacitor connected in series with the switching element, the path through which the short-circuit current flows can be changed to either a capacitive impedance characteristic or an inductive impedance characteristic according to the frequency of the current.

[0019] Preferably, part or all of the magnets are variable flux magnets with low coercive force. Variable flux magnets can be used, for example, in variable magnetic force motors of vehicles, and the magnetic force of the magnets can be changed by demagnetizing or magnetizing the magnets. Therefore, depending on the operating state, the loss during motor driving can be reduced, and the efficiency of the motor can be improved. In addition, "variable flux magnets with low coercive force" refers to "magnets with a coercive force lower than the magnetic field that can be applied by the coils of the motor, and whose magnetic force can be changed by demagnetizing or magnetizing the magnets."

[0020] Preferably, the device further comprises a control unit for controlling the driving frequency of the motor and the operation of the switching unit. The control unit may control the driving frequency to a first predetermined frequency, and control the switching unit so that the current supply lines are connected to demagnetize the magnet. Preferably, the first predetermined frequency is substantially equal to or higher than the resonant frequency of a resonant circuit composed of a circuit including the coil of the motor and a circuit of the switching unit.

[0021] In addition, the control unit may control the driving frequency to a second predetermined frequency, control the switching unit, connect the current supply lines, and magnetize the magnet. Preferably, the second predetermined frequency is lower than the first predetermined frequency. Preferably, the second predetermined frequency is substantially equal to or lower than the resonant frequency.

[0022] The path has a resonance point due to the presence of a capacitor connected in series with the switching element, and the path becomes a capacitive impedance characteristic at a second predetermined frequency lower than the resonance point, and becomes an inductive impedance characteristic at a first predetermined frequency higher than the resonance point. Therefore, at the first predetermined frequency, the coil generates a magnetic field suitable for demagnetizing the magnet, and at the second predetermined frequency, the coil easily generates a magnetic field suitable for magnetizing the magnet. In addition, the frequency corresponds to the driving speed (e.g., the rotation speed) of the motor.

[0023] The control device may further include an inverter that supplies currents with phase differences to the motor. By using the inverter, currents of a predetermined frequency can be supplied to the motor with phase differences, and the motor can be operated at a predetermined driving speed (eg, rotation speed).

[0024] The motor of the present invention is a motor having any of the above control devices, preferably a motor having a rotor and a stator, but may also include other motors such as a linear motor. The magnet is preferably provided on the rotor, but may also be provided on the stator.

[0025] The present invention provides a control device for a generator, which comprises:

[0026] a current supply line for supplying currents having phase differences to each coil of a generator having a magnet; and

[0027] A switching unit switches between a non-connected state and a connected state between the current supply lines.

[0028] In a generator, a moving body such as a rotor is moved by utilizing forces such as water power, wind power, geothermal steam, and wave power, so that an induced electromotive force is generated in a coil facing a magnet to output power. However, magnets of generators such as wind turbines are sometimes demagnetized or demagnetized due to reasons such as lightning strikes. In such cases, large-scale operations such as recovery, transportation, and disassembly of the magnets of the generator are required, which results in huge maintenance costs, especially in offshore wind turbines.

[0029] In the generator control device of the present invention, by using the same device as the above-mentioned motor control device, it is possible to easily remagnetize the magnets of the generator without replacing the magnets of the generator. In addition, by using the same device as the above-mentioned motor control device, it is also possible to expect to improve the efficiency of the generator by freely demagnetizing and magnetizing the magnets of the generator.

[0030] Similar to the control device for the electric motor, in the control device for the generator, it is preferable that the switching unit includes a switching element that switches between a disconnected state and a connected state between the current supply lines.

[0031] In addition, similar to the control device for the electric motor, the control device for the generator may further include (at least one or more) a capacitor connected in series with the switching element.

[0032] Preferably, the control device of the generator further comprises a detection unit for detecting a driven frequency of a driven body in the generator and a control unit for controlling the operation of the switching unit. Preferably, the control unit controls the switching unit to connect the current supply lines and magnetize the magnet when it is detected that the driven frequency detected by the detection unit is substantially equal to or less than the resonant frequency of a resonant circuit constituted by a circuit including a coil of the generator and a circuit of the switching unit.

[0033] When the driven frequency detected by the detection unit is lower than the resonant frequency of the resonant circuit, if the switching unit is controlled to connect the current supply lines, the increase in the amplitude of the current supplied by the inverter or the like is insufficient, and it is sometimes difficult to magnetize the magnet. On the other hand, when the driven frequency detected by the detection unit exceeds the resonant frequency of the resonant circuit, if the switching unit is controlled to connect the current supply lines, the amplitude of the current supplied by the inverter or the like is amplified, for example, by more than 3 times. As a result, the applied magnetic field applied to the magnet also increases, and the magnet can be effectively magnetized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1A This is a conceptual diagram of a motor control device according to an embodiment of the present invention.

[0035] Figure 1B This is a conceptual diagram of a generator control device according to another embodiment of the present invention.

[0036] Figure 2A It is a cross-sectional view showing an example of a motor.

[0037] Figure 2B It is a cross-sectional view showing an example of a generator.

[0038] Figure 3 This is a graph showing a B-H curve of a magnet used in a motor, and is a diagram showing the principle of demagnetization and magnetization.

[0039] Figure 4A Yes means Figure 1A FIG. 2 is a graph of phase currents showing an example of the operation of the switching element shown.

[0040] Figure 4B Yes means Figure 1A Graph of phase current showing another example of the operation of the switching element shown.

[0041] Figure 4C Yes means Figure 1B Graph of phase currents showing an operation example of a switching element shown.

[0042] Figure 5A It means Figure 4A A graph showing the change in the magnetic field applied to the magnet.

[0043] Figure 5B It means Figure 4B A graph showing the change in the magnetic field applied to the magnet.

[0044] Figure 5C It means Figure 4C A graph showing the change in the magnetic field applied to the magnet. DETAILED DESCRIPTION

[0045] Hereinafter, embodiments shown in the drawings will be described.

[0046] First embodiment

[0047] like Figure 1A As shown, the motor control device 10 of this embodiment is a device for controlling the operation of the motor 30, and includes a main control unit 20, a circuit 40 for supplying current to the motor 30, a voltage source 48, an inverter 46, a switching unit 44, and the like.

[0048] In this embodiment, as the motor 30 controlled by the motor control device 10, Figure 2AThe motor of the structure shown is used as an example for explanation, but it can also be a motor of other structures, such as an interior permanent magnet synchronous motor (IPMSM), other PM (permanent magnet) motors, etc. Or it can also be a linear motor.

[0049] like Figure 1A As shown, the main control unit 20 of the motor control device 10 outputs a command for controlling the motor 30 to the inverter 46 and the switching unit 44. As an example, the main control unit 20 may output a control signal to the inverter 46 and the switching unit 44, or may output command data including data for controlling the motor 30.

[0050] In addition, the main control unit 20 obtains information such as the rotation speed of the motor 30. As an example, the main control unit 20 may also obtain information such as the rotation speed of the motor 30 via a rotary transformer or a converter. In addition, the method of obtaining the rotation speed of the motor, the position of the rotor, etc. is not particularly limited, and an appropriate method may be selected according to the type of the motor, the control method, etc.

[0051] The main control unit 20 has a command output unit 22, an operation control unit 24, a current and speed adjustment unit 25, an input unit 26, a storage unit 27, etc. In addition, each unit such as the operation control unit 24, the current and speed adjustment unit 25, the input unit 26, and the storage unit 27 is a block representing the function of controlling the motor 30, and can be implemented as an independent device or processing unit, or two or more parts can be merged, or one part can be further divided. These devices can be configured using, for example, a microprocessor or a memory, in which case, the function of the motor control device 10 can also be implemented by executing appropriate software / programs. The main control unit 20 can also be configured using, for example, one or more dedicated hardware devices (integrated circuits, etc.).

[0052] Figure 1A The command output unit 22 shown in the figure instructs the circuit 40 including the coil 32 included in the motor 30 to output the current supplied to the coil 32. For example, the command output unit 22 can control the rotor 33 of the motor 30 by controlling the inverter 46 or the switching unit 44 to adjust the output of the current (see Figure 2A ) or controls the rotation of the magnet 34 (see Figure 2A ) or demagnetization of magnet 34.

[0053] The command output unit 22 is controlled by the operation control unit 24, the current and speed adjustment unit 25, the storage unit 27, etc. Figure 1AIn the embodiment, the command output unit 22 is configured as a part of the main control unit 20, but may be configured as a part different from the main control unit 20. The instruction of the current output by the command output unit 22 will be described in detail later.

[0054] The main control unit 20 controls the command output unit 22 based on information related to the current value of the circuit 40, information on the rotation speed of the motor 30, external input information input via the input unit 26, etc. The command output unit 22 controlled by the main control unit 20 outputs a command related to the current supplied to the motor 30 to the inverter 46 or the switching unit 44.

[0055] The current / speed adjustment unit 25 calculates an adjustment value of the output of the current supplied to the circuit 40 based on information related to the current value of the circuit 40, information on the speed (rotation speed) of the motor 30, external input information input via the input unit 26, etc. The current / speed adjustment unit 25 can perform dq conversion of the AC signal based on, for example, the UVW three-phase AC signal from the circuit 40, information on the rotation speed of the motor 30, and external input information, and can also calculate the gains of the d-axis and q-axis currents.

[0056] The operation control unit 24 performs operation control of the motor 30 such as non-interference control. For example, the operation control unit 24 performs signal processing to eliminate the influence of the q-axis current on the d-axis voltage, the influence of the d-axis current and magnetic flux on the q-axis voltage, and calculates the voltage of each axis. Through such non-interference control of the operation control unit 24, the interference between the d-axis and the q-axis can be reduced or eliminated, and the control device 10 of the motor can independently control the d-axis and the q-axis.

[0057] Figure 1A The storage unit 27 shown stores information used in calculations by the operation control unit 24. The operation control unit 24 can read information from the storage unit 27 as necessary and use the information for calculations related to the control of the motor 30.

[0058] Towards Figure 1A The input unit 26 of the motor control device 10 shown in the figure inputs external input information such as speed (rotation speed) command and current command related to the motor 30. The external input information input to the input unit 26 is transmitted to the main control unit 20 and used for controlling the motor 30.

[0059] Figure 2A It is a schematic representation Figure 1A The sectional view of the internal structure of the motor 30 shown in FIG. The motor 30 includes a rotor 33 having a plurality of magnets 34 and a stator 31 having a plurality of coils 32. Figure 2AIn the specific example shown, the motor 30 includes 12 coils 32 arranged at substantially equal intervals in the circumferential direction. Ten magnets 34 are arranged at substantially equal intervals in the circumferential direction on the rotor 33, which can rotate with the approximate center position of the rotor 33 as the rotation center.

[0060] like Figure 2A As shown, the coil 32 is arranged so as to surround the rotor 33 having the magnet 34. The magnet 34, which is a permanent magnet, is attached to the surface of the rotor 33, but may be buried inside.

[0061] The magnetic field formed by the coil 32 exerts an electromagnetic force on the magnet 34, thereby rotating the rotor 33 of the motor 30. When the coil 32 forms a strong magnetic field around the magnet 34, the magnet 34 is magnetized or demagnetized by the formed magnetic field. Figure 1A and Figure 2A In the motor 30 shown in FIG. 1 , the coil 32 for rotating the motor 30 and the coil 32 for magnetizing or demagnetizing the magnet 34 are common, but as Figure 1A The motor controlled by the motor control device 10 shown is not limited to this.

[0062] For example, the motor controlled by the motor control device 10 may be configured to magnetize or demagnetize the magnet 34 using a coil 32 different from the coil 32 that rotates the motor, or may be configured to magnetize or demagnetize the magnet 34 using a part of the coil 32 that rotates the motor 30 .

[0063] The magnet 34 of this embodiment is not particularly limited, and may be a sintered magnet or a bonded magnet. The material of the magnet is not particularly limited, and examples thereof include R-T-B permanent magnets, Sm-Co permanent magnets, ferrite permanent magnets, and aluminum-nickel permanent magnets. In addition, as the magnet, a variable flux magnet with a low coercive force is preferably used.

[0064] A variable flux magnet is a magnet that can switch its magnetization state by a magnetic field from the outside, and can reversibly realize a high magnetization state and a low magnetization state. In a variable magnetic force motor equipped with such a variable flux magnet, the magnetic field can be controlled according to the rotation speed and load state. For example, when high torque is required (at low rotation or high load), the magnetization state of the variable flux magnet is controlled in a manner that displays a large magnetic flux, and when high torque is not required (at high rotation or low load), the magnetization state of the variable flux magnet is controlled in a manner that displays a small magnetic flux. With such a variable flux magnet, the efficiency of the variable magnetic force motor can be improved regardless of the torque value.

[0065] like Figure 1AAs shown, power is supplied to the coil 32 of the motor 30 through the current supply lines 42a, 42b, 42c of the circuit 40. The coil 32 of the motor 30, the switching unit 44, the inverter 46, etc. are connected to the current supply lines 42a, 42b, 42c of the circuit 40.

[0066] The inverter 46 uses the DC voltage from the voltage source 48 to make the circuit 40 generate a predetermined current and voltage based on the command from the command output unit 22. Specifically, the inverter 46 supplies three-phase AC current (current of a predetermined frequency) of UVW with different phases to each current supply line 42a, 42b, 42c. Figure 1A In the illustrated system, a DC voltage realized by a battery is used as the voltage source 48 , but the voltage source 48 for driving the motor 30 is not limited thereto, and the voltage source may be an AC voltage.

[0067] Figure 1A The switching unit 44 shown has a switching switch element 44a1, which switches between a non-connected state and a connected (short-circuited) state between the current supply lines 42a and 42b that supply currents having phase differences to the coil 32. In addition, the switching unit 44 has a switching switch element 44a2, which switches between a non-connected state and a connected state between the current supply lines 42b and 42c that supply currents having phase differences to the coil 32.

[0068] In the present embodiment, the switch unit 44 includes capacitors 44b1 and 44b2 connected in series to the switch elements 44a1 and 44a2, respectively.

[0069] The command output unit 22 of the main control unit 20 sends a control signal to the switching unit 44, or does not send a control signal, so that the switch elements 44a1 and 44a2 of the switching unit 44 are turned off. When the switch elements 44a1 and 44a2 are turned off, the current supply lines 42a, 42b, and 42c are kept disconnected from each other. In this case, the three-phase phase current from the inverter 46 to the coil 32 is maintained, for example, Figure 4A Before the timing t1 shown ( Figure 4A The state of t1 on the left side).

[0070] In this state, Figure 1A The coils 32 of the motor 30 shown in the figure are supplied with three-phase alternating currents having phase differences with each other, and the rotor 33 of the motor 30 (see Figure 2A ) operates normally at a first speed corresponding to a first specified frequency. Figure 4A The timing t1 shown in the figure is Figure 2AWhen the magnet 34 provided in the rotor 33 of the motor 30 shown in FIG. 1 is demagnetized, Figure 1A The main control unit 20 shown sends a control signal to the switching unit 44 to turn on the switch elements 44a1 and 44a2. As a result, the current supply lines 42a, 42b, and 42c are connected via the capacitors 44b1 and 44b2.

[0071] When the current supply lines 42a, 42b, and 42c having a phase difference are connected, a short-circuit current flows between each pair of lines via the capacitor, thereby Figure 4A After the timing t1 ( Figure 4A As shown in FIG. 1 , the amplitude of the current increases. Therefore, a larger current (for example, more than twice) than that in normal operation can be passed through the coil 32 of the motor 30 without changing the output of the inverter 46 or the like. As a result, Figure 5A After the timing t1, Figure 2A The magnet 34 of the illustrated motor 30 applies a magnetic field that is higher on the negative side (for example, 1.8 times or more) than the magnetic field applied during normal operation, and the magnet 34 can be demagnetized.

[0072] For example, Figure 3 As shown in FIG. 1 , for the hysteresis curve 34a of the B-H curve of the magnet 34, in this embodiment, demagnetization can be performed with a sufficiently large magnetic field ml1 (on the negative side). Figure 1A In the conventional control device of the switching unit 44 shown in FIG. 1 , when demagnetization is performed, demagnetization is performed using the magnetic field ml0. That is, in this embodiment, even if the magnetic field is further reduced, Figure 1A The output of the inverter 46 shown can also be demagnetized.

[0073] In addition, at the timing t2 (refer to Figure 4A ),from Figure 1A The main control unit 20 shown sends a control signal to the switching unit 44 to turn off the switch elements 44a1 and 44a2. As a result, the connection between the current supply lines 42a, 42b, and 42c is cut off, and the short-circuit current does not flow. In addition, in this embodiment, the short-circuit current refers to the current that flows between the current supply lines 42a, 42b, and 42c through or without the capacitors 44b1 and 44b2 before the current is supplied to the motor 30.

[0074] When the connection between the current supply lines 42a, 42b, 42c is cut off, the current flowing in each current supply line 42a, 42b, 42c is as follows: Figure 4A After the timing t2 ( Figure 4ASimilarly, when the connection between the current supply lines 42a, 42b, and 42c is cut off, the applied magnetic field supplied to each magnet 34 of the motor 30 is as shown in FIG. Figure 5A After the timing t2 ( Figure 5A As shown on the right side of FIG. 3 , the motor 30 returns to the state before the timing t1. As a result, the motor 30 returns to normal operation.

[0075] In addition, Figure 4A and Figure 5A In the figure, the electrical angle of the horizontal axis corresponds to the elapsed time. The elapsed time from timing t1 to t2 is, for example, within a few milliseconds to a few seconds, during which all the magnets 34 of the motor 30 are demagnetized. After the magnets 34 are demagnetized, Figure 1A The main control unit 20 shown performs normal control of the electric motor 30 .

[0076] Next, when magnetizing the magnet of the motor 30, first, Figure 1A The main control unit 20 shown in FIG. 1 controls the motor 30 so that the rotor 33 (see FIG. Figure 2A ) rotates at a second rotational speed corresponding to a second predetermined frequency. The second rotational speed (second predetermined frequency) is lower than the first rotational speed (first predetermined frequency) described above.

[0077] For example, in this embodiment, when the first drive frequency is set to Fd1, the second drive frequency is set to Fd2, and the resonant frequency of the resonant circuit determined by the capacitance of the capacitors 44b1 and 44b2, the inductance of the coil 32, etc. is set to Fr, Fd1 / Fr is preferably greater than 1.0 and less than 3.0, and more preferably greater than 1.0 and less than 2.0. Fd2 / Fr is preferably greater than 0.3 and less than 1.0, and more preferably greater than 0.6 and less than 1.0.

[0078] Afterwards, for example Figure 4B The timing t1a shown is to make Figure 2A The magnet 34 of the rotor 33 of the motor 30 shown is magnetized. Figure 1A The main control unit 20 shown sends a control signal to the switching unit 44 to turn on the switch elements 44a1 and 44a2. As a result, the current supply lines 42a, 42b, and 42c are connected via the capacitors 44b1 and 44b2.

[0079] When the current supply lines 42a, 42b, and 42c having a phase difference are connected, a short-circuit current flows between each pair of lines via the capacitor, thereby Figure 4B After the timing t1a ( Figure 4B As shown on the right side of t1a, the current amplitude increases. Therefore, it is possible to Figure 1A The output of the inverter 46 shown in FIG. 4A is used to make a larger current (for example, three times or more) than that in normal operation flow through the coil 32 of the motor 30. As a result, Figure 5B After the timing t1a, Figure 2A The magnet 34 of the illustrated motor 30 applies a magnetic field that is higher (for example, three times or more) on the positive side than the magnetic field applied during normal operation, and the magnet 34 can be magnetized.

[0080] For example, Figure 3 As shown in FIG. 1 , with respect to the hysteresis curve 34a of the B-H curve of the magnet 34, in this embodiment, it is possible to magnetize with a sufficiently large magnetic field mh1 (on the positive side). Figure 1A In the conventional control device of the switching unit 44 shown in FIG. 1 , when magnetization is performed, the magnetic field mh0 is used for magnetization. That is, in this embodiment, it is possible to increase the Figure 1A The magnetization is performed by the output of the inverter 46 shown.

[0081] In addition, at the timing t2a (refer to Figure 4B ),from Figure 1A The main control unit 20 shown sends a control signal to the switching unit 44 to turn off the switch elements 44a1 and 44a2. As a result, the connection between the current supply lines 42a, 42b, and 42c is cut off, and the short-circuit current does not flow.

[0082] When the connection between the current supply lines 42a, 42b, 42c is cut off, the current flowing in each current supply line 42a, 42b, 42c is as follows: Figure 4B After the timing t2a ( Figure 4B Similarly, when the connection between the current supply lines 42a, 42b, and 42c is cut off, the applied magnetic field supplied to each magnet 34 of the motor 30 is as shown in FIG. Figure 5B After the timing t2a ( Figure 5B As shown on the right side of FIG. 3 , the motor 30 returns to the state before the timing t1a. As a result, the motor 30 returns to normal operation.

[0083] In addition, Figure 4B and Figure 5B In, with Figure 4A and Figure 5A Similarly, the electrical angle of the horizontal axis also corresponds to the elapsed time. The elapsed time from timing t1a to t2a may be the same as or different from the elapsed time from timing t1 to t2, for example, within a few milliseconds to a few seconds, during which all the magnets 34 of the motor 30 are magnetized. After the magnetization of the magnets 34 is completed, Figure 1AThe main control unit 20 shown performs normal control of the electric motor 30 .

[0084] In this embodiment, if Figure 1A As shown, due to the presence of capacitors 44b1 and 44b2 connected in series to the switching elements 44a1 and 44a2, the path through which the short-circuit current flows can be changed to either a capacitive impedance characteristic or an inductive impedance characteristic according to the frequency of the current.

[0085] The presence of capacitors 44b1 and 44b2 connected in series with the switching elements 44a1 and 44a2 causes the path to have a resonance point, and at a second predetermined frequency lower than the resonance point, the path becomes a capacitive impedance characteristic, and at a first predetermined frequency higher than the resonance point, the path becomes an inductive impedance characteristic. Therefore, at the first predetermined frequency, the coil 32 generates a magnetic field suitable for demagnetizing the magnet 34, and at the second predetermined frequency, the coil 32 easily generates a magnetic field suitable for magnetizing the magnet 34. In addition, the predetermined frequency corresponds to the driving speed (e.g., the rotation speed) of the motor.

[0086] Second embodiment

[0087] Figure 1B The control device 10a of the generator 30a of the embodiment shown is used for example in a wind turbine, but is not limited thereto and may be used for example in a hydroelectric generator, a geothermal steam generator, a wave generator, a tidal current generator, a tidal current generator, and the like.

[0088] The generator 30a has Figure 2B The structure of the motor 30 shown is the same as that of the motor 30, and includes a rotor connected to a driving force generating source such as a windmill (driven body) to rotate, and a stator having coils 32a similar to the coils 32 arranged around it. On the rotor, magnets similar to the magnets 34 are mounted similarly to the motor 30.

[0089] like Figure 1B As shown, the main control unit 20a of the generator control device 10a outputs a command for controlling the generator 30a to the inverter 46 and the switching unit 44. As an example, the main control unit 20a may output a control signal to the inverter 46 and the switching unit 44, or may output command data including data for controlling the generator 30a.

[0090] like Figure 1B As shown, the main control unit 20a of the generator control device 10a outputs a command for controlling the generator 30a to the inverter 46 and the switching unit 44. As an example, the main control unit 20a may output a control signal to the inverter 46 and the switching unit 44, or may output command data including data for controlling the generator 30a.

[0091] In addition, the main control unit 20a obtains information such as the rotation speed of the generator 30a. As an example, the main control unit 20 preferably obtains information such as the rotation speed (driven frequency) of the windmill (driven body) of the generator 30a via a detection unit 29 such as a rotary transformer or a converter. In addition, the detection unit 29 for obtaining the rotation speed (driven frequency) of the generator, the position of the rotor, etc. is not particularly limited, and an appropriate detection unit can be selected based on the type of the generator, the control method, etc.

[0092] The main control unit 20a includes a command output unit 22a, an operation control unit 24a, a current and speed adjustment unit 25a, an input unit 26a, and a storage unit 27a. In addition, the command output unit 22a, the operation control unit 24a, the current and speed adjustment unit 25a, the input unit 26a, and the storage unit 27a correspond to the command output unit 22, the operation control unit 24, the current and speed adjustment unit 25, the input unit 26, and the storage unit 27 of the first embodiment. However, since these control objects are different in the motor 30 and the generator 30a, there are parts with slightly different functions. Hereinafter, the parts not particularly described are the same as those of the first embodiment.

[0093] In this embodiment, the configurations of the voltage source 48, the inverter 46, and the switching unit 44 are the same as those of the first embodiment. The generator 30a of this embodiment is connected to the output unit 60 via the input / output force switching unit 50. The output unit 60 is a circuit for outputting the induced electromotive force generated in the coil 32a of the generator 30a to the outside.

[0094] The input / output switching unit 50 includes switching elements 54a, 54b, 54c for switching the output lines 52a, 52b, 52c respectively connected to the three-phase coil 32a to be connected to the output unit 60 and to be connected to the current supply lines 42a, 42b, 42c. Figure 1B The main control unit 20a shown controls the output lines 52a, 52b, 52c via the switching elements 54a, 54b, 54c so as to maintain the connection with the output unit 60. Thus, the power generated by the generator 30a can be taken out from the output unit 60 to the outside.

[0095] When the magnet of the generator 30a needs to be demagnetized or magnetized for some reason, the main control unit 20a sends a signal to the input / output switching unit 50 to switch the output lines 52a, 52b, 52c to be connected to the current supply lines 42a, 42b, 42c, respectively. In addition, the main control unit 20a controls the rotor of the generator 30a to be disconnected from the power source such as wind power, so that the rotor of the generator 30a can rotate freely regardless of the power source, as needed.

[0096] In this state, the magnet can be demagnetized and magnetized as in the first embodiment described above. In addition, unlike the first embodiment described above, in this embodiment, the rotor of the generator 30a can be rotated by natural energy such as wind power. Therefore, in this embodiment, the switching element of the switching unit 44 for short circuit can be controlled to be turned on and off according to the rotation speed to control the demagnetization or magnetization of the magnet.

[0097] For example, magnets of generators such as wind turbines are sometimes demagnetized or demagnetized due to lightning strikes, etc. In such cases, large-scale operations such as recovery, transportation, and disassembly of the generator magnets for replacement are required, which results in huge maintenance costs, especially in offshore wind turbines.

[0098] In the control device 10a of the generator 30a of the present embodiment, by using the same device as the control device 10 of the motor 30 of the first embodiment described above, it is possible to easily remagnetize the magnets of the generator 30a without replacing the magnets. In addition, by using the same device 10a as the control device 10 of the motor 30 of the first embodiment described above, it is possible to expect to improve the efficiency of the generator 30a by freely performing demagnetization and magnetization of the magnets of the generator 30a.

[0099] In the present embodiment, the voltage source 48 may be a power storage device that stores a portion of the power taken out from the output unit 60 of the generator 30a. In the generator 30a of the present embodiment, the coil 32a for outputting power also serves as a coil for demagnetizing or magnetizing the magnet of the generator 30a, but they may be prepared separately.

[0100] Third embodiment

[0101] In this embodiment, Figure 1B The specific structure of the generator 30a shown in the figure is different from that of the second embodiment. Figure 2B The structure shown is the same as that of the second embodiment described above, except that it has the structure of the control device 10a shown below, and the repeated description is omitted.

[0102] like Figure 2B As shown, the generator 30a of this embodiment has a cylindrical rotor 33a as a rotor connected to a driving force generating source such as a windmill (driven body) and rotated. On the inner peripheral surface of the rotor 33a, a plurality of magnets 34 are arranged at approximately equal intervals in the circumferential direction. In addition, a shaft 31a as a stator having coils 32a arranged in a manner opposite to these magnets 34 at a predetermined interval is attached to the inner side of the rotor 33a.

[0103] The control device 10a of the generator 30a of the present embodiment has a control Figure 1B The main control unit 20a for the operation of the switching unit 44 shown in the figure, and the detection unit 29 for detecting the driven frequency of the windmill or the like as the driven body in the generator 30a. The detection unit 29 is, for example, arranged near the driven body of the generator 30a, and is not particularly limited. For example, a rotation angle sensor such as a rotary transformer, an angular velocity sensor, and other sensors that can obtain information such as the rotation speed (driven frequency) of the windmill (driven body) or the like can be exemplified.

[0104] The main control unit 20a has a comparison unit 28 that compares the driven frequency detected by the detection unit 29 with the resonant frequency of a resonant circuit formed by a circuit including the coil 32a of the generator 30a and a switching unit 44 or a capacitor included in another circuit (circuit from the inverter to the generator 30a). The main control unit 20a determines in the comparison unit 28 whether the driven frequency from the detection unit 29 is substantially equal to or lower than the resonant frequency of the resonant circuit stored in, for example, the storage unit 27a. When the comparison unit 28 detects that the driven frequency is substantially equal to or lower than the resonant frequency, the switching elements 44a1 and 44a2 of the switching unit 44 are controlled to connect the current supply lines 42a, 42b, and 42c, and perform Figure 2B The magnetization of magnet 34 is shown.

[0105] When the driven frequency detected by the detection unit 29 is smaller than the resonant frequency of the resonant circuit, for example, less than 0.3 times, and assuming that the switching unit 44 is controlled to connect the current supply lines 42a, 42b, and 42c, the amplitude of the current supplied by the inverter 46, etc. is not increased sufficiently, and it is sometimes difficult to magnetize the magnet 34.

[0106] On the other hand, when it is detected that the driven frequency detected by the detection unit 29 is substantially equal to or lower than the resonant frequency of the resonant circuit, at the timing t1a (see Figure 4C ), the switch 44 is controlled to connect the current supply lines 42a, 42b, and 42c. Figure 4C As shown in FIG. 1 , the amplitude of the current supplied by the inverter 46 and the like is amplified by more than 3 times. As a result, Figure 5C As shown, after time t1a, the magnetic field applied to the magnet 34 also becomes larger, and the magnet can be magnetized efficiently.

[0107] For example, the magnet 34 of a generator such as a wind turbine is sometimes demagnetized or demagnetized due to a lightning strike, etc. In this case, large-scale operations such as recovery, transportation, and replacement of the magnets of the generator are required, which would result in huge maintenance costs, particularly in offshore wind turbines.

[0108] In the control device 10a of the generator 32a of the present embodiment, by using the same device as the control device 10a of the generator 30a of the second embodiment described above, the magnet 34 can be easily magnetized without replacing the rotor 33a of the generator 30a including the magnet 34. In addition, by using the same device 10a as the control device 10a of the generator 30a of the second embodiment described above, the magnet 34 of the generator 30a can be easily re-magnetized.

[0109] This can reduce the costs of collecting, transporting, disassembling the generator, replacing the magnets, etc., and eliminate the need for large-scale operations. In particular, it is possible to achieve a significant reduction in maintenance costs in offshore wind turbines.

[0110] In addition, Figure 4C and Figure 5C In the figure, the electrical angle of the horizontal axis corresponds to the elapsed time. The elapsed time from timing t1 to t2 is, for example, within a few milliseconds to a few seconds, during which all the magnets 34 of the generator 30a are magnetized. After the magnets 34 are magnetized, Figure 1B The main control unit 20 shown performs normal control of the generator 30a.

[0111] In addition, in the present embodiment, when the driven frequency of the driven body detected by the detection unit 29 is set to Fd and the resonant frequency of the resonant circuit is set to Fr, Fd / Fr is preferably 0.3 or more and less than 1.0, and more preferably 0.6 or more and less than 1.0. Furthermore, in the present embodiment, the driven frequency detected by the detection unit 29 may be not only the rotation frequency of a windmill, etc., but also a motion frequency other than rotation. In addition, the frequency of the three-phase current used for magnetization in the generator is preferably lower than the resonant frequency of the circuit, as in the case of the motor.

[0112] The present invention is not limited to the first, second, and third embodiments described above, and these elements may be combined to form a modified embodiment, or elements of the above-described embodiments may be omitted to form a modified embodiment.

[0113] For example, in Figure 1A or Figure 1B In the illustrated embodiment, the switch elements 44a1 and 44a2 and the capacitors 44b1 and 44b2 are provided between the current supply lines 42a and 42b and between the current supply lines 42b and 42c among the three current supply lines 42a, 42b, and 42c, but the present invention is not limited to these.

[0114] For example, if a switch element is provided between any one or more pairs of the three current supply lines 42a, 42b, and 42c, the same effect as in the above embodiment can be achieved. However, it is preferred that a switch element is provided between any two or more pairs of the three current supply lines 42a, 42b, and 42c. More preferably, at least one capacitor is connected in series with each switch element.

[0115] In addition, it is preferred that capacitors 44b1 and 44b2 are connected in series with the switch elements between any one or more pairs of current supply lines 42a, 42b, and 42c in the switch section 44, but the present invention is not limited thereto. For example, even if no capacitor is provided in the switch section 44, a capacitor connected in series with each switch element 44a1 and 44a2 may be provided at any position of the circuit 40 or 40a.

[0116] In addition, the capacitor connected in series with the switching element may be arranged inside the motor 30 or the generator 30a or inside the inverter 46. However, when the current supply lines 42a, 42b, and 42c are disconnected from each other by the switching elements 44a1 and 44a2, the capacitor is preferably arranged in series with the switching element between the current supply lines from the viewpoint of stopping the function of the capacitor.

[0117] In addition, in the above-mentioned embodiment, a variable flux magnet with low coercivity is used as the magnet 34, but it is not limited to this. At least one or more of the multiple magnets 34 constituting the magnetic poles of the motor 30 (the same applies to the generator) may also be a variable flux magnet with low coercivity. In addition, for example, at least one or more of the multiple magnets 34 may also be a composite of multiple magnets including a variable flux magnet with low coercivity and a fixed flux magnet with high coercivity. In the composite, the variable flux magnet and the fixed flux magnet may be arranged in series, in parallel, or in a composite arrangement. In addition, the magnet 34 may also be composed of only a fixed flux magnet with high coercivity.

[0118] Furthermore, the motor of the above-mentioned embodiment is a motor having a rotor and a stator, but it may be another motor such as a linear motor. In addition, the magnet is preferably provided on the rotor, but it may also be provided on the stator. In addition, the command output unit 22, 22a, the operation control unit 24, 24a, the current / speed adjustment unit 25, 25a, the input unit 26, 26a, and the comparison unit 28 in the main control unit 20, 20a of the above-mentioned embodiment may be composed of a dedicated circuit, but may also be a program executed by a computer.

[0119] Description of Reference Numerals

[0120] 10…Motor control device

[0121] 10a…Generator control device

[0122] 20, 20a…main control unit

[0123] 22, 22a ... command output unit

[0124] 24, 24a…Operation control unit

[0125] 25, 25a…current and speed adjustment unit

[0126] 26, 26a…Input section

[0127] 27, 27a ... storage unit

[0128] 28…Comparison

[0129] 29…Detection Department

[0130] 30…Electric motor

[0131] 30a...Generator

[0132] 31…stator

[0133] 31a…stator (shaft)

[0134] 32, 32a…coil

[0135] 33, 33a…rotor

[0136] 34…Magnet

[0137] 34a…Hysteresis curve

[0138] 40...Circuit

[0139] 42a, 42b, 42c ...current supply lines

[0140] 44…Switching unit

[0141] 44a1, 44a2…Switching element

[0142] 44b1, 44b2...capacitors

[0143] 46…Inverter

[0144] 48…Voltage source

[0145] 50…Input / output switching unit

[0146] 52a, 52b, 52c…output lines

[0147] 54a, 54b, 54c ... switch elements

[0148] 60…output section.

Claims

1. A control device for an electric motor, comprising: a current supply line for supplying currents having phase differences to each coil of the motor having the magnet; and A switching unit switches between a non-connected state and a connected state between the current supply lines.

2. The control device for the electric motor according to claim 1, wherein: The switching unit includes a switch element that switches between a disconnected state and a connected state between the current supply lines.

3. The control device for the electric motor according to claim 2, wherein: A capacitor is also provided which is connected in series with the switching element.

4. The control device for the electric motor according to claim 1, wherein: Some or all of the magnets are low coercive force variable flux magnets.

5. The control device for the electric motor according to claim 1, wherein: further comprising a control unit for controlling the driving frequency of the motor and the operation of the switching unit, In the control unit, The driving frequency is controlled to be a first predetermined frequency, and the switching unit is controlled so that the current supply lines are connected to each other, thereby demagnetizing the magnet.

6. The control device for the electric motor according to claim 5, wherein: In the control unit, The driving frequency is controlled to be a second predetermined frequency, the switching unit is controlled to connect the current supply lines, and the magnet is magnetized. The second prescribed frequency is lower than the first prescribed frequency.

7. The control device for the electric motor according to claim 1, wherein: An inverter is further provided, which supplies currents having a phase difference to the electric motors. 8 . An electric motor comprising the electric motor control device according to claim 1 .

9. A control device for a generator, comprising: a current supply line for supplying currents having phase differences to each coil of a generator having a magnet; and A switching unit switches between a non-connected state and a connected state between the current supply lines.

10. The control device for the generator according to claim 9, wherein: The switching unit includes a switch element that switches between a disconnected state and a connected state between the current supply lines.

11. The control device for a generator according to claim 10, wherein: A capacitor is also provided which is connected in series with the switching element.

12. The control device for a generator according to any one of claims 9 to 11, wherein: The device further comprises a detection unit for detecting a driven frequency of a driven object in the generator and a control unit for controlling the operation of the switching unit. In the control unit, when it is detected that the driven frequency detected by the detection unit is substantially equal to or lower than the resonant frequency of a resonant circuit composed of a circuit including a coil of the generator and a circuit of the switching unit, the switching unit is controlled to connect the current supply lines and magnetize the magnet. 13 . A generator comprising the generator control device according to claim 9 .

14. A wind power generator comprising the generator control device according to any one of claims 9 to 12.

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