Charging device

Abstract

This charging device comprises: a rotating machine having a first winding, a second winding, and a field winding; a first inverter connected to the first winding; a second inverter connected to the second winding; a third inverter connected to the field winding; and a controller for outputting a gate signal to the third inverter and controlling the field current flowing through the field winding. In a charging operation, the first inverter converts a DC current into an AC current and supplies the AC current to the first winding, the second inverter converts the AC current of the second winding induced by the AC current of the first winding into a DC current and supplies the DC current to the battery, and the controller controls the field current so that the rotating shaft of the rotating machine does not rotate.

Description

charging device

[0001] This application claims priority to Japanese Patent Application No. 2024-102516, filed on Jun. 26, 2024, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a charging device that charges a battery with power from an AC power supply source.

[0003] Japanese Patent Application Publication No. 2014-239599

[0004] Charging devices for charging batteries generally use dedicated converters. However, rather than using a dedicated converter, using a rotating machine with multiple multiphase windings and an inverter for driving the rotating machine together as a converter contributes to cost and space savings. However, when using a rotating machine and an inverter as a charging device, rotational torque is generated in the rotating machine during power conversion, and this rotational torque can cause vibrations and noise.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to suppress vibrations and noise caused by rotational torque when performing power conversion in a configuration in which a rotating machine and an inverter are used as a charging device.

[0006] One aspect of the present disclosure is a charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a field winding; a first inverter connected to the first winding; a second inverter connected to the second winding; a third inverter connected to the field winding; and a controller that outputs a gate signal to the third inverter to control a field current flowing through the field winding, wherein in a charging operation, the first inverter converts a direct current into an alternating current and supplies it to the first winding, the second inverter converts the alternating current in the second winding induced by the alternating current in the first winding into a direct current and supplies it to the battery, and the controller controls the field current so that the rotating shaft of the rotating machine does not rotate.

[0007] According to the present disclosure, it is possible to provide a charging device that uses a rotating machine and an inverter to contribute to space saving, and that can suppress vibrations and noise caused by rotational torque when performing power conversion.

[0008] 1 is a block diagram of a charging system according to first to seventh embodiments. It is an electrical circuit diagram of the periphery of the rotating machine in FIG. 1. It is a block diagram explaining the function of generating a first gate signal and a second gate signal in a controller according to first and second embodiments. It is a block diagram explaining the function of generating a third gate signal in a controller according to second embodiment. It is a diagram explaining the winding arrangement on the stator side of a rotating machine having a double winding structure according to third embodiment. It is a diagram explaining the winding arrangement on the stator side of a rotating machine having a triple winding structure according to third embodiment. It is a line voltage waveform of a first inverter explaining the charging operation in fourth to seventh embodiments. It is a line voltage waveform of a second inverter explaining the charging operation in fourth to seventh embodiments. It is a block diagram explaining the function of generating a first gate signal and a second gate signal in a controller according to fourth to seventh embodiments. It is a diagram explaining the first gate signal and the second gate signal output by the controller in the charging operation in fourth to seventh embodiments. It is a diagram explaining the current waveform flowing in the first winding in the charging operation in fourth to seventh embodiments. It is a line voltage waveform of a first inverter explaining the discharging operation in fourth to seventh embodiments. 10 is a diagram illustrating a line voltage waveform of the second inverter, explaining the discharge operation in the fourth to seventh embodiments. FIG. 11 is a diagram illustrating a first gate signal and a second gate signal output by the controller in the discharge operation in the fourth to seventh embodiments. FIG. 12 is a diagram illustrating a current waveform flowing through the second winding 4 in the discharge operation in the fourth to seventh embodiments. FIG. 13 is a diagram illustrating a modification of the charging system in the fourth to seventh embodiments. FIG. 14 is a table illustrating the relationship between the two phases to be energized and the rotor position at the start of power conversion in the sixth embodiment. FIG. 15 is a flowchart for determining whether to energize a field current in the seventh embodiment. FIG. 16 is a block diagram of a charging system in the eighth embodiment.

[0009] 1 is an overall block diagram of a charging system 100 including a charging device 13 according to Embodiment 1. The charging system 100 includes a first connection terminal 12, a charging device 13, a second connection terminal 15, a third connection terminal 11, and a battery 16. The charging device 13 includes a rotating machine 1, a first inverter 5, a second inverter 6, a first current sensor 7, a second current sensor 8, a third current sensor 9, a third inverter 10, and a controller 14. The rotating machine 1 includes a field winding 2, a first winding 3, and a second winding 4.

[0010] The rotating machine 1 may be, for example, a drive motor for an automobile. That is, the charging device 13 and the charging system 100 may be mounted on a vehicle. The rotating machine 1 may also constitute a so-called e-axle. An e-axle is a unit that integrates a motor, a reducer, and an inverter. However, the rotating machine 1 does not have to be integrated with an inverter or the like. The charging device 13 and the charging system 100 may also be used for purposes other than vehicles.

[0011] The rotating machine 1 in this embodiment is a so-called wound-field dual three-phase rotating machine having dual three-phase windings on the stator side. The rotating machine 1 in this embodiment is non-salient and does not generate reluctance torque. Furthermore, the rotating machine 1 in this embodiment controls the field flux by the field current to the field winding. However, the rotating machine 1 may be a claw-pole type having a magnet in the rotor, for example. The first current sensor 7 and the second current sensor 8 may detect the currents of each of the three phases (U, V, W). Alternatively, the first current sensor 7 and the second current sensor 8 may detect the currents of two of the three phases (U, V, W) and calculate the current value of the remaining phase based on the detection results. The charging system 100 may be configured to perform feedback control based on the detection result of the first current sensor 7. Alternatively, the first current sensor 7 may be omitted by using feedforward control.

[0012] The first connection terminal 12, the second connection terminal 15, and the third connection terminal 11 are used to connect the charging device 13 to a configuration external to the charging device 13. The second connection terminal 15 can be connected to the positive and negative poles of the battery 16. The third connection terminal 11 can be connected to the positive and negative pole wires of the battery 16.

[0013] The first connection terminal 12 is connected to the first inverter 5. The first inverter 5 is connected to the first winding 3 of the rotating machine 1. The first current sensor 7 measures the current flowing between the first inverter 5 and the first winding 3. The second connection terminal 15 is connected to the second inverter 6. The second inverter 6 is connected to the second winding 4 of the rotating machine 1. The second current sensor 8 measures the current flowing between the second inverter 6 and the second winding 4. The third connection terminal 11 is connected to the third inverter 10. The third inverter 10 is connected to the field winding 2 of the rotating machine 1. The third current sensor 9 measures the current flowing between the third inverter 10 and the field winding 2. For example, a current transformer (CT) can be used as the first current sensor 7, the second current sensor 8, and the third current sensor 9.

[0014] The first current sensor 7 is connected to the controller 14 via three control lines. The first current sensor 7 inputs a measurement value of a three-phase current flowing between the first inverter 5 and the first winding 3 to the controller 14 as a first current measurement value I1. The second current sensor 8 is connected to the controller 14 via three control lines. The second current sensor 8 inputs a measurement value of a three-phase current flowing between the second inverter 6 and the second winding 4 to the controller 14 as a second current measurement value I2. The third current sensor 9 is connected to the controller 14 via one control line. The third current sensor 9 inputs a measurement value of a current flowing between the third inverter 10 and the field winding 2 to the controller 14 as a third current measurement value I3. Note that the number of control lines connecting the components is merely an example and can be changed as appropriate.

[0015] The rotating machine 1 can be regarded as a three-phase isolated transformer, with the first winding 3 and the second winding 4 wound around one stator tooth. The first inverter 5 connected to the first winding 3 and the second inverter 6 connected to the second winding 4 can be regarded as forming an isolated DC-DC converter circuit.

[0016] Figure 2 is a circuit diagram showing the peripheral configuration of the rotating machine 1 shown in Figure 1. The first winding 3 includes a U-phase winding 3u, a V-phase winding 3v, and a W-phase winding 3w. The second winding 4 includes a U-phase winding 4u, a V-phase winding 4v, and a W-phase winding 4w. The U-phase winding 3u, the V-phase winding 3v, and the W-phase winding 3w are star-connected. The U-phase winding 4u, the V-phase winding 4v, and the W-phase winding 4w are star-connected.

[0017] 2, the first inverter 5 includes first upper arm switching elements 5uH, 5vH, 5wH and first lower arm switching elements 5uL, 5vL, 5wL. The first upper arm switching elements 5uH, 5vH, 5wH are connected to the positive pole of a DC power supply via a first connection terminal 12. The first lower arm switching elements 5uL, 5vL, 5wL are connected to the negative pole of the DC power supply via a first connection terminal 12. The first lower arm switching elements 5uL, 5vL, 5wL are connected to the first upper arm switching elements 5uH, 5vH, 5wH, respectively.

[0018] In this embodiment, the first inverter 5 and the second inverter 6 have a so-called three-phase full-bridge inverter circuit. Each switching element of the first inverter 5, the second inverter 6, and the third inverter 10 may be, for example, a field effect transistor (FET). More specifically, each switching element may be a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0019] The first U-phase contact 5u, located between the first upper arm switching element 5uH and the first lower arm switching element 5uL, is connected to the U-phase winding 3u. The first V-phase contact 5v, located between the first upper arm switching element 5vH and the first lower arm switching element 5vL, is connected to the V-phase winding 3v. The first W-phase contact 5w, located between the first upper arm switching element 5wH and the first lower arm switching element 5wL, is connected to the W-phase winding 3w.

[0020] The second inverter 6 includes second upper arm switching elements 6uH, 6vH, and 6wH and second lower arm switching elements 6uL, 6vL, and 6wL. The second lower arm switching elements 6uL, 6vL, and 6wL are connected to the second upper arm switching elements 6uH, 6vH, and 6wH, respectively.

[0021] The second U-phase contact 6u, located between the second upper arm switching element 6uH and the second lower arm switching element 6uL, is connected to the U-phase winding 4u. The second V-phase contact 6v, located between the second upper arm switching element 6vH and the second lower arm switching element 6vL, is connected to the V-phase winding 4v. The second W-phase contact 6w, located between the second upper arm switching element 6wH and the second lower arm switching element 6wL, is connected to the W-phase winding 4w.

[0022] The rotating machine 1, the first inverter 5, and the second inverter 6 operate as follows. As shown in FIG. 1 , a DC voltage is input to the first connection terminal 12 from a DC power source 101 external to the charging device 13. When the charging system 100 is mounted on a vehicle, for example, the vehicle is connected to a charging stand, and the DC voltage is supplied from the DC power source 101 included in the charging stand. The DC voltage may be supplied to the first connection terminal 12 by other means. For example, a household outlet may be connected to the charging system 100. The first inverter 5 converts the DC voltage input via the first connection terminal 12 into a three-phase AC voltage and outputs it to the first winding 3 of the rotating machine 1. When the three-phase AC voltage is applied to the first winding 3, a three-phase AC voltage is induced in the second winding 4, which is magnetically coupled to the first winding 3. The three-phase AC voltage induced in the second winding 4 is rectified by the second inverter 6 and converted into a DC voltage.

[0023] The controller 14 outputs a first gate signal G1 for controlling the first inverter 5 to the first inverter 5. The controller 14 outputs a second gate signal G2 for controlling the second inverter 6 to the second inverter 6. The controller 14 outputs a third gate signal G3 for controlling the third inverter 10 to the third inverter 10.

[0024] The configuration of the controller 14 will be described with reference to Fig. 3. The controller 14 has a current command value calculator 18, a PI controller 19, an interference compensator 20, a carrier generator 21, a comparator 22, and a dead time adder 23. Control by the controller 14 will be described later.

[0025] Next, the operation of the charging system 100 according to the first embodiment will be described with reference to FIGS. 1 and 3. FIG.

[0026] Charging operation in embodiment 1. A DC voltage from a DC power source 101 is input to the first connection terminal 12. The DC voltage input to the first connection terminal 12 is converted to an AC voltage by the first inverter 5 and supplied to the first winding 3 of the rotating machine 1. At this time, the controller 14 outputs a first gate signal G1 to each of the switching elements 5uH, 5vH, 5wH, 5uL, 5vL, and 5wL of the first inverter 5 so that a three-phase balanced current flows from the first inverter 5 to the first winding 3.

[0027] The measurement value by the first current sensor 7 is input to the controller 14. In this embodiment, the controller 14 performs PI control so that the charging current flows according to the target value. The control by the controller 14 will be described with reference to FIG. 3 . The current command value calculator 18 determines a current command value, for example, according to the charging current. The current command value calculator 18 may output a current command value from which harmonic components have been subtracted. The deviation between this current command value and the first current measurement value I1, which is the measurement result of the first current sensor 7, is input to the PI controller 19.

[0028] Regarding the gain of the PI controller 19, interference compensation is performed using an interference compensator 20 to convert the first winding 3 and the second winding 4 into first-order lag elements of resistance and inductance. The first winding 3 and the second winding 4 have a low resistance structure to reduce copper loss. The integral gain of the PI controller 19 is the product of the resistance value and the crossover frequency. To improve responsiveness, the crossover frequency of the integral gain is set higher than the crossover frequency of the proportional gain. In this embodiment, a control method is adopted in which the first current measurement value I1 measured by the first current sensor 7 is forwarded back to the PI controller 19. However, the controller 14 may also perform feedforward control. When feedforward control is adopted, the first current sensor 7 is not required.

[0029] As shown in FIG. 3 , interference compensation is performed by adding the output value of the interference compensator 20 to the output value of the PI controller 19. The sum of the output value of the PI controller 19 and the output value of the interference compensator 20 is input to the comparator 22. A triangular wave carrier output from the carrier generator 21 is input to the comparator 22. The comparator 22 generates a basic gate signal by comparing the sum of the output value of the PI controller 19 and the output value of the interference compensator 20 with the triangular wave carrier. The basic gate signal generated by the comparator 22 is input to the dead time adder 23. The dead time adder 23 adds dead time to the basic gate signal to prevent arm short circuits in the first inverter 5 and the second inverter 6. The dead time adder 23 outputs the first gate signal G1 generated in this manner to the first inverter 5.

[0030] The first gate signal G1 operates the switching elements 5uH, 5vH, 5wH, 5uL, 5vL, and 5wL of the first inverter 5, causing a three-phase balanced current to flow through the first winding 3 of the rotating machine 1. Because the first winding 3 and the second winding 4 are magnetically coupled, a three-phase balanced current also flows through the second winding 4 due to an induced voltage. By turning off all of the second gate signals G2 directed to the second inverter 6, the switching elements 6uH, 6vH, 6wH, 6uL, 6vL, and 6wL of the second inverter 6 function as diodes. The three-phase balanced current flowing through the second winding 4 is rectified by the diodes and supplied as DC current to the second connection terminal 15. The DC current is supplied to the battery 16 via the second connection terminal 15, charging the battery 16. The second current measurement value I2 measured by the second current sensor 8 is input to the controller 14 as a control signal.

[0031] The DC voltage of the battery 16 is input to the third inverter 10 via the third connection terminal 11. The controller 14 outputs a third gate signal G3 to the third inverter 10 to turn off all switching elements (e.g., FETs) of the third inverter 10. This suppresses the flow of field current through the field winding 2 during charging. The rotating machine 1 in the first embodiment is a motor that does not generate reluctance torque, so no torque is generated even when current flows through the first winding 3 and the second winding 4. Furthermore, since no field current is passed and field flux does not link the first winding 3 and the second winding 4, no torque is generated by the field flux. The torque at this time is sufficiently small so that the rotating shaft of the rotating machine 1 does not rotate. A third current measurement value I3 measured by the third current sensor 9 is input to the controller 14 as a control signal. However, during charging, the third current measurement value I3 is not reflected in the third gate signal G3 because no current flows from the third inverter 10 to the field winding 2. Therefore, the third current sensor 9 is not essential.

[0032] Discharge Operation in First Embodiment. Next, the operation when discharging from the battery 16 to the first connection terminal 12 will be described. When the charging system 100 is mounted on a vehicle, the present disclosure may be applied to so-called V2H (Vehicle To Home) applications. That is, power from the battery 16 may be supplied from the vehicle to a building such as a residence. The power from the battery 16 is supplied to the second inverter 6 via the second connection terminal 15. The second inverter 6 converts the DC power from the battery 16 to AC power and supplies it to the second winding 4 of the rotating machine 1. At this time, the controller 14 outputs a second gate signal G2 to the second inverter 6 so that a three-phase balanced current flows from the second inverter 6 to the second winding 4. The control of the controller 14 will be described using FIG. 3. The second current measurement value I2 measured by the second current sensor 8 is input to the controller 14.

[0033] The controller 14 performs PI control so that the discharge current flows according to the target value. The current command value calculator 18 may output a current command value on which harmonic components are superimposed. The PI controller 19 receives the deviation between the current command value and the second current measurement value I2 measured by the second current sensor 8. Regarding the gain of the PI controller 19, interference compensation is performed using an interference compensator 20 to convert the first winding 3 and the second winding 4 into first-order lag elements of resistance and inductance. In this embodiment, a control method is adopted in which the second current measurement value I2 measured by the second current sensor 8 is forwarded back to the PI controller 19. However, the controller 14 may also perform feedforward control. When feedforward control is adopted, the second current sensor 8 is not required.

[0034] As shown in FIG. 3 , interference compensation is performed by adding the value of the interference compensator 20 to the output value of the PI controller 19. The sum of the output value of the PI controller 19 and the output value of the interference compensator 20 is input to the comparator 22. A triangular wave carrier output from a carrier generator 21 is input to the comparator 22. The comparator 22 generates a basic gate signal by comparing the sum of the output value of the PI controller 19 and the output value of the interference compensator 20 with the triangular wave carrier. The basic gate signal generated by the comparator 22 is input to the dead time adder 23. The dead time adder 23 adds dead time to prevent arm short circuits in the first inverter 5 and the second inverter 6. The dead time adder 23 outputs the second gate signal G2 generated in this manner to the second inverter 6.

[0035] The second gate signal G2 operates the switching elements 6uH, 6vH, 6wH, 6uL, 6vL, and 6wL of the second inverter 6, causing a three-phase balanced current to flow through the second winding 4 of the rotating machine 1. Because the second winding 4 and the first winding 3 are magnetically coupled, a three-phase balanced current also flows through the first winding 3 due to an induced voltage. At this time, by turning off all of the first gate signals G1 directed to the first inverter 5, the switching elements 5uH, 5vH, 5wH, 5uL, 5vL, and 5wL of the first inverter 5 function as diodes. The three-phase balanced current flowing through the first winding 3 is rectified by these diodes and output as a DC current to the first connection terminal 12. The DC current is supplied to the outside of the charging system 100 via the first connection terminal 12 and used.

[0036] The first current measurement value I1 measured by the first current sensor 7 is input to the controller 14 as a control signal. The DC voltage of the battery 16 is input to the third inverter 10 via the third connection terminal 11. The controller 14 outputs a third gate signal G3 to the third inverter 10 to turn off all switching elements of the third inverter 10. This suppresses the flow of field current through the field winding 2 during the discharge operation. The rotating machine 1 in the first embodiment is a motor that does not generate reluctance torque, so no torque is generated even when current flows through the first winding 3 and the second winding 4. Furthermore, because no field current is passed and field flux does not link the first winding 3 and the second winding 4, no torque is generated due to the field flux. The torque at this time is sufficiently small so that the rotating shaft of the rotating machine 1 does not rotate. The third current measurement value I3 measured by the third current sensor 9 is input to the controller 14 as a control signal. However, in the discharging operation, since no field current flows from the third inverter 10 to the field winding 2, the third current measurement value I3 is not reflected in the third gate signal G3.

[0037] As described above, the charging device 13 not only charges but also discharges. Therefore, the charging device 13 can also be called a "charging / discharging device." Similarly, the charging system 100 can also be called a "charging / discharging system."

[0038] As described above, the present disclosure relates to a charging device 13 that charges a battery 16. The charging device 13 according to the first embodiment includes a rotating machine 1 having a first winding 3, a second winding 4, and a field winding 2, a first inverter 5 connected to the first winding 3, a second inverter 6 connected to the second winding 4, a third inverter 10 connected to the field winding 2, and a controller 14 that outputs a gate signal G3 to the third inverter 10 to control a field current flowing through the field winding 2. In a charging operation, the first inverter 5 converts a direct current from the first connection terminal 12 into an alternating current and supplies the alternating current to the first winding 3, the second inverter 6 converts an alternating current in the second winding 4 induced by the alternating current in the first winding 3 into a direct current and supplies the direct current to the battery 16, and the controller 14 controls the field current so that the rotating shaft of the rotating machine 1 does not rotate. More specifically, the controller 14 according to the first embodiment does not allow a field current to flow through the field winding 2 when performing power conversion between the first inverter 5 and the second inverter 6 .

[0039] Advantages of the First Embodiment In the present embodiment, no field current flows through the field winding 2 during charging. Therefore, even in a configuration in which the rotating machine 1 is used as an isolation transformer, the field flux does not interlink with the first winding 3 and the second winding 4, resulting in a sufficiently small rotational torque and preventing the rotating shaft of the rotating machine 1 from rotating. This prevents vibration and noise caused by rotational torque during charging. Furthermore, although rotational torque may occur as a result of an error between the actual rotor position of the motor and the rotor position estimated by the controller due to the influence of a position sensor, a current sensor, and harmonic components of the magnetic flux of the magnet, the absence of field flux linkage prevents the generation of vibration and noise caused by such rotational torque. Another advantage is that the current flow is flexible, allowing for the adoption of a highly efficient power conversion method. Furthermore, removing harmonic components superimposed on the first winding 3 and the second winding 4 reduces harmonic copper loss and harmonic iron loss. This improves charging efficiency.

[0040] Modification of First Embodiment In the above description, MOSFETs have been exemplified as the switching elements that constitute the first inverter 5, the second inverter 6, and the third inverter 10. However, other power devices such as IGBTs (Insulated Gate Bipolar Transistors) may also be used as these switching elements.

[0041] In the above description, during charging, the controller 14 outputs the second gate signal G2 so that the switching elements 6uH, 6vH, 6wH, 6uL, 6vL, and 6wL of the second inverter 6 are turned OFF. However, to reduce conduction loss in the second winding 4, the controller 14 may perform synchronous rectification. In this case, the controller 14 outputs the second gate signal G2 so that the switching elements 6uH, 6vH, 6wH, 6uL, 6vL, and 6wL of the second inverter 6 are switched ON / OFF at a predetermined timing.

[0042] In the above description, during the discharge operation, the controller 14 outputs the first gate signal G1 so that the switching elements 5uH, 5vH, 5wH, 5uL, 5vL, and 5wL of the first inverter 5 are turned OFF. However, to reduce conduction loss in the first winding 3, the controller 14 may perform synchronous rectification. In this case, the controller 14 outputs the first gate signal G1 so that the switching elements 5uH, 5vH, 5wH, 5uL, 5vL, and 5wL of the first inverter 5 are switched ON / OFF at a predetermined timing.

[0043] In the above description, CTs are used as the first current sensor 7, the second current sensor 8, and the third current sensor 9. However, shunt resistors may be used as the first current sensor 7, the second current sensor 8, and the third current sensor 9. Although the first inverter 5 and the second inverter 6 have been described as having three-phase full-bridge inverter circuits, a multilevel inverter circuit such as a three-level inverter circuit may also be used.

[0044] In the above description, the output current of the first inverter 5 or the second inverter 6 is controlled to be a three-phase balanced current during charging and discharging. However, in this embodiment, the rotational torque is suppressed by not linking the field flux to the first winding 3 and the second winding 4. Therefore, the output current of the first inverter 5 or the second inverter 6 may be controlled to be an unbalanced current, as in a DAB (Dual Active Bridge) converter or a flyback converter.

[0045] In the above description, the controller 14 includes the PI controller 19. However, the controller 14 may include a controller other than the PI controller. Although the rotating machine 1 has been described using a wound-field dual three-phase rotating machine as an example, the present disclosure can also be applied to multiplex multi-phase rotating machines such as triple three-phase rotating machines and triple six-phase rotating machines.

[0046] Second Embodiment Next, a second embodiment of the present disclosure will be described. The second embodiment has the same basic configuration as the first embodiment. Therefore, the following mainly describes the differences from the first embodiment, and the same components are denoted by the same reference numerals and their description will be omitted. The overall configuration of the charging system 100 in the second embodiment is the same as that shown in FIG. 1. The rotating machine 1 in the second embodiment differs from the first embodiment in that it has a salient pole and generates reluctance torque. Furthermore, as shown in FIG. 4, the configuration of the controller 14 in the second embodiment differs from that in the first embodiment.

[0047] Charging Operation in Embodiment 2 As in Embodiment 1, the DC current input to the first connection terminal 12 is converted to an AC current by the first inverter 5 and supplied to the first winding 3 of the rotating machine 1. Here, the controller 14 in this embodiment outputs a first gate signal G1 to the first inverter 5 so that a three-phase balanced current corresponding to the rotor position flows from the first inverter 5 to the first winding 3. The rotor position can be estimated from the three-phase balanced current. The DC voltage of the battery 16 is input to the third inverter 10 via the third connection terminal 11.

[0048] In this embodiment, the controller 14 outputs a third gate signal G3 to the third inverter 10 so that a field current for canceling out the rotational torque of the rotating machine 1 flows from the third inverter 10 to the field winding 2. The controller 14 in this embodiment will be described with reference to Fig. 4. As shown in Fig. 4, the controller 14 according to this embodiment has a torque estimator 24, a field current command value calculator 25, a PI controller 26, an interference compensator 27, a comparator 28, a carrier generator 29, and a dead time adder 30.

[0049] As shown in FIG. 4 , the controller 14 receives a third current measurement value I3, which is the measurement result of the third current sensor 9. The torque estimator 24 receives a first current measurement value I1 and a second current measurement value I2, which are measurement results of the first current sensor 7 and the second current sensor 8. The torque estimator 24 calculates a torque estimation value based on the first current measurement value I1 and the second current measurement value I2. The torque estimation value is an estimate of the rotational torque acting on the rotor of the rotating machine 1. The torque estimator 24 inputs the torque estimation value to a field current command value calculator 25. The field current command value calculator 25 calculates a field current command value based on the torque estimation value. A deviation between the field current command value and the third current measurement value I3 is input to a PI controller 26, and the PI controller 26 performs PI control.

[0050] In this embodiment, a field current is passed through the field winding 2 so as to cancel out the rotational torque generated in the first winding 3 and the second winding 4. For this purpose, the crossover frequency of the loop transmission gain in the control system for the field current is set to a value higher than the crossover frequency of the loop transmission gain in the control system for the current flowing through the first winding 3 and the second winding 4. As a specific example, if the crossover frequency of the loop transmission gain in the control system for the current flowing through the first winding 3 and the second winding 4 is 500 rad / s, the gain of the PI controller 26 may be set so that the crossover frequency of the loop transmission gain in the control system for the field current is 3000 rad / s.

[0051] As shown in Fig. 4, interference compensation is performed by adding the output value of the interference compensator 27 to the output value of the PI controller 26. The sum of the output value of the PI controller 26 and the output value of the interference compensator 27 is input to the comparator 28. A triangular wave carrier output from a carrier generator 29 is input to the comparator 28. The comparator 28 generates a basic gate signal by comparing the sum of the output value of the PI controller 26 and the output value of the interference compensator 27 with the triangular wave carrier. The basic gate signal generated by the comparator 28 is input to the dead time adder 30.

[0052] The dead time adder 30 adds dead time to the basic gate signal to prevent arm short-circuiting in the third inverter 10. The dead time adder 30 outputs the third gate signal G3 generated in this manner to the third inverter 10. As a result, a field current flows from the third inverter 10 to the field winding 2. When the first winding 3 and the second winding 4 perform power conversion, the rotational torque of the rotating machine 1, which is generated by the flow of a three-phase balanced current, is canceled out by the field current. Therefore, the rotational torque generated in the rotating machine 1 is small enough to prevent the rotating shaft from rotating.

[0053] Discharge Operation in Embodiment 2 As in Embodiment 1, the DC current of the battery 16 is converted to AC current by the second inverter 6. Here, the controller 14 in this embodiment outputs a second gate signal G2 to the second inverter 6 so that a three-phase balanced current corresponding to the rotor position flows from the second inverter 6 to the second winding 4. The rotor position can be estimated from the three-phase balanced current. Even in the discharge operation, a field current is passed through the field winding 2 so as to cancel out the rotational torque generated in the first winding 3 and the second winding 4. The specific operation of the controller 14 is the same as in the charge operation, and therefore will not be described in detail.

[0054] Effects of the Second Embodiment As described above, the controller 14 according to the second embodiment flows a field current through the field winding 2 when power conversion is performed between the first inverter 5 and the second inverter 6, so as to cancel out the rotational torque generated by the current flowing through the first winding 3 and the second winding 4. Furthermore, the open-loop transfer gain of the control system for the field current flowing through the field winding 2 is set higher than the open-loop transfer gain of the control system for the current flowing through the first winding 3 and the second winding 4. This configuration allows the rotational torque generated when power is converted by the first winding 3 and the second winding 4 to be canceled out with high response by controlling the field current. Therefore, vibrations and noise caused by the rotational torque can be prevented during charging or discharging. Furthermore, harmonic copper loss and harmonic iron loss can be reduced by removing harmonic components superimposed on the first winding 3 and the second winding 4. Therefore, the efficiency of charging and discharging can be improved.

[0055] Modification of Embodiment 2 In the above description, a control method is adopted in which the third current measurement value I3 measured by the third current sensor 9 is forwarded back to the PI controller 26. However, feedforward control may also be adopted. When feedforward control is adopted, the third current sensor 9 is not essential.

[0056] The rotating machine 1 according to this embodiment is not limited to a field structure having only a field winding, and may employ a field structure having both a permanent magnet and a field winding. Furthermore, the rotating machine 1 may have either an axial gap structure or a radial gap structure. Furthermore, the rotor position may be measured using a position sensor instead of being estimated from the three-phase balanced current. Additionally, the modifications described in the first embodiment may also be applied to the second embodiment.

[0057] Third Embodiment Next, a third embodiment of the present disclosure will be described. The third embodiment has the same basic configuration as the first embodiment. Therefore, the following mainly describes the differences from the first embodiment, and the same components are denoted by the same reference numerals and will not be described again. The overall configuration of the charging system 100 in the third embodiment is the same as that shown in FIG. 1. As shown in FIG. 5, in this embodiment, the arrangement of the stator-side windings of the first winding 3 and the second winding 4 will be described.

[0058] FIG. 5 is a cross-sectional view of 0.5 turns of any one of the three-phase windings included in the first winding 3 and the second winding 4. In FIG. 5, black circles (●) and Xs (×) indicate the winding direction. Black circles indicate windings wound from the back to the front of the page, and Xs indicate windings wound from the front to the back. The winding shown in FIG. 5 is distributed winding and wave winding. Because FIG. 5 is a cross-sectional view, the first windings 3A to 3F are shown separately, but the first windings 3A to 3F are one of the three-phase windings of the first winding 3. Therefore, the first windings 3A to 3F are actually connected together. The second windings 4A to 4F are also one of the three-phase windings of the second winding 4 and are connected together.

[0059] As shown in FIG. 5 , the stator of the rotating machine 1 has stator teeth 31. The stator teeth 31 have multiple tooth openings 31A to 31F. The first winding 3A, an insulating material 32A, and a second winding 4A are arranged in the tooth opening 31A. The first winding 3B, an insulating material 32B, and a second winding 4B are arranged in the tooth opening 31B. The first winding 3C, an insulating material 32C, and a second winding 4C are arranged in the tooth opening 31C. The first winding 3D, an insulating material 32D, and a second winding 4D are arranged in the tooth opening 31D. The first winding 3E, an insulating material 32E, and a second winding 4E are arranged in the tooth opening 31E. The first winding 3F, an insulating material 32F, and a second winding 4F are arranged in the tooth opening 31F.

[0060] For example, in the tooth opening 31A, the second winding 4A, the insulating material 32A, and the first winding 3A are arranged in this order from the inside to the outside in the radial direction. Although not shown, the second winding 4A, the insulating material 32A, and the first winding 3A are arranged parallel to one another inside the tooth opening 31A along the axial direction of the rotating machine 1. The same arrangement is also true for the tooth openings 31B to 31F. In other words, the insulating materials 32A to 32F are arranged radially between the second windings 4A to 4F and the first windings 3A to 3F. Furthermore, the insulating materials 32A to 32F, the second windings 4A to 4F, and the first windings 3A to 3F are arranged parallel to one another along the axial direction.

[0061] Effects of Embodiment 3 In this embodiment, the first winding 3 and the second winding 4 are arranged parallel to each other in the axial direction (perpendicular to the plane of the paper in FIG. 5 ) within the opening of the same stator tooth 31. This increases the mutual inductance generated between the first winding 3 and the second winding 4. This has the effect of increasing the conversion efficiency when power is converted between the first winding 3 and the second winding 4. Furthermore, even if there is a potential difference between the first winding 3 and the second winding 4, short circuits can be prevented because an insulating material is arranged between the first winding 3 and the second winding 4.

[0062] Modification of Embodiment 3. The first winding 3 and the second winding 4 have been described as being wound using distributed winding and wave winding, but they may also be wound using concentrated winding or mixed-phase winding. Even in these cases, the same effect can be achieved by arranging the first winding 3 and the second winding 4 parallel to the axial direction inside one of the tooth openings 31A to 31F. The first windings 3A to 3F may also be arranged radially inward of the second windings 4A to 4F. In this case, the same effect can be achieved by arranging insulating materials 32A to 32F between the second windings 4A to 4F and the first windings 3A to 3F.

[0063] FIG. 5 illustrates a winding method when the rotating machine 1 is a dual three-phase rotating machine. However, as shown in FIG. 6, the rotating machine 1 may also be a triple three-phase rotating machine. Specifically, the first winding 3A, the insulating material 32A, the second winding 4A, the insulating material 32A', and the third winding 3A' may be arranged in this order from the radially outer side to the radially inner side inside one tooth opening 31A. As long as insulating material is sandwiched between the windings in this manner, similar effects can be achieved in multiple multi-phase rotating machines other than dual three-phase rotating machines. Furthermore, as shown in FIG. 6, the teeth 31 may be formed of multiple tooth pieces 34. In addition, the modifications described in the first and second embodiments may also be applied to the third embodiment.

[0064] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described. The fourth embodiment has the same basic configuration as the first embodiment. Therefore, the following mainly describes the differences from the first embodiment, and the same components are denoted by the same reference numerals and will not be described again. The overall configuration of the charging system 100 in the fourth embodiment is the same as that shown in FIG. 1. However, the control during the charging operation or discharging operation differs from that in the first and second embodiments. The control in this embodiment will be described below with reference to FIGS. 1, 2, 7, 8, 9, 10, 11, 12, 13, 14, and 15.

[0065] Charging Operation in Embodiment 4. The DC voltage input to the first connection terminal 12 is converted into power by the first inverter 5 and the second inverter 6. At this time, the controller 14 outputs a first gate signal G1 to the first inverter 5 and a second gate signal G2 to the second inverter so as to obtain the line voltage waveforms shown in FIGS. 7 and 8. In FIGS. 7 and 8, the horizontal axis represents time and the vertical axis represents voltage. FIG. 7 shows the waveform of the voltage between the contacts 5u and 5v in FIG. 2. The symbol "5uv" in FIG. 7 indicates the voltage between the contacts 5u and 5v. FIG. 8 shows the waveform of the voltage between the contacts 6u and 6v in FIG. 2. The symbol "6uv" in FIG. 8 indicates the voltage between the contacts 6u and 6v.

[0066] Here, in the charging operation of the battery 16 from the DC power source 101 connected to the first connection terminal 12, the first inverter 5 is defined as the reference phase, and the second inverter 6 is defined as the control phase. The phase difference between point 41 in FIG. 7 (the line voltage of the first inverter 5) and point 42 in FIG. 8 (the line voltage of the second inverter 6) is defined as the control phase difference φ [°]. The control phase difference φ [°] can be set within a range from −180° to +180°. Changing the control phase difference φ [°] changes the current value and, therefore, the transmission power. That is, the controller 14 controls the current command values ​​for the first winding 3 and the second winding 4 in the first and second inverters 5 and 6 to change the control phase difference, thereby controlling the transmission power in the power conversion from the first inverter 5 to the second inverter 6. Furthermore, the controller 14 may control the current command value so that the average value of point 41 in Fig. 7 (the line voltage of the first inverter 5) and the average value of point 42 in Fig. 8 (the line voltage of the second inverter 6) both become zero. Regarding the rotor position of the rotating machine 1, the position at which the magnetic flux linking with the U-phase winding 3u of the first winding 3 becomes maximum when a field current is applied is defined as 0°. However, power conversion may be started from any rotor position.

[0067] The control of the controller 14 related to the charging operation of the fourth embodiment will be described with reference to FIG. 9 . The controller 14 according to the fourth embodiment includes a current measurement value calculator 33, a current command value calculator 35, a PI controller 36, a phase shift controller 37, a PWM signal generator 38, and a duty ratio output unit 39. The first current measurement value I1 is input to the current measurement value calculator 33. The current measurement value calculator 33 calculates a combined current A flowing from the first connection terminal 12 to the first inverter 5 using the first current measurement value I1 and a first gate signal G1 output to the first inverter 5.

[0068] The PI controller 36 receives an input of the deviation between the output from the current command value calculator 35 and the composite current A, which is the output from the current measurement value calculator 33. Based on this deviation, the PI controller 36 performs PI control. A gain is set so that the output of the PI controller 36 becomes the control phase difference φ [°]. The output of the PI controller 36, i.e., the control phase difference φ [°], is input to a PWM signal generator 38 via a phase shift controller 37. A duty ratio output unit 39 also inputs a duty ratio to the PWM signal generator 38. In this embodiment, the duty ratio is, for example, 0.5.

[0069] The PWM signal generator 38 generates a first gate signal G1 for switching the switching elements 5uH, 5vH, 5uL, and 5vL (see FIG. 2) associated with the U and V phases of the first inverter 5. To perform single-phase operation in the W phase of the first inverter 5, the switching elements 5wH and 5wL associated with the W phase are turned OFF. The PWM signal generator 38 also generates a second gate signal G2 for switching the switching elements 6uH, 6uL, 6vH, and 6vL associated with the U and V phases of the second inverter 6. The second gate signal G2 is generated relative to the first gate signal G1 so as to generate a control phase difference φ [°] between the reference phase and the control phase, as shown in FIGS. 7 and 8 . To perform single-phase operation in the W phase of the second inverter 6, the switching elements 6wH and 6wL associated with the W phase are turned OFF.

[0070] The first gate signal G1 and the second gate signal G2 are provided with dead times to prevent arm short circuits in the first inverter 5 and the second inverter 6. As an example, FIG. 10 shows the first gate signal G1 and the second gate signal G2 when the control phase difference φ is 90° and the duty ratio is 0.5. The switching elements 5wH, 5wL, 5wH, and 6wL related to the W phases of the first inverter 5 and the second inverter are all OFF, and therefore are omitted from FIG. 10 . In FIG. 10 , the horizontal axis represents time. In FIG. 10 , time periods marked with a symbol such as "5uL" indicate that the corresponding switching element 5uL is ON, and time periods without a symbol indicate that the switching element is OFF.

[0071] The first gate signal G1 shown in Fig. 10 causes a current as shown in Fig. 11 to flow through the first winding 3 of the rotating machine 1. This causes power conversion between the first winding 3 and the second winding 4. The DC voltage of the battery 16 is input to the third inverter 10 via the third connection terminal 11. The controller 14 outputs a third gate signal G3 so that all switching elements of the third inverter 10 are turned OFF. This prevents a field current from flowing through the field winding 2.

[0072] Even if a current flows through the first winding 3 and the second winding 4, if no field current flows, the field flux does not interlink with the first winding 3 and the second winding 4, and the rotational torque becomes small enough to prevent the rotating shaft of the rotating machine 1 from rotating. Furthermore, since the rotating machine 1 has a non-salient pole structure, reluctance torque is not generated in principle. The third current measurement value I3 measured by the third current sensor 9 is input to the controller 14 as a control signal. However, in this embodiment, since no current flows from the third inverter 10 to the field winding 2, the third current measurement value I3 is not reflected in the third gate signal G3. Therefore, the third current sensor 9 is not essential.

[0073] Discharge Operation in Embodiment 4. DC power input from the battery 16 to the third connection terminal 11 is converted by the second inverter 6 and the first inverter 5. At this time, the controller 14 outputs a first gate signal G1 to the first inverter 5 and a second gate signal G2 to the second inverter so as to obtain the line voltage waveforms shown in FIGS. 12 and 13. In FIGS. 12 and 13, the horizontal axis represents time and the vertical axis represents voltage. FIG. 12 shows the waveform of the voltage between the contacts 5u and 5v in FIG. 2. The symbol "5uv" in FIG. 12 indicates the voltage between the contacts 5u and 5v. FIG. 13 shows the waveform of the voltage between the contacts 6u and 6v in FIG. 2. The symbol "6uv" in FIG. 13 indicates the voltage between the contacts 6u and 6v.

[0074] Here, in the discharge operation from the battery 16 to the first connection terminal 12, the second inverter 6 is set as the reference phase and the first inverter 5 is set as the control phase. As in the charging operation, the phase difference between point 41 in Fig. 12 and point 42 in Fig. 13 is defined as the control phase difference φ [°]. The rotor position is also defined as in the charging operation.

[0075] The control of the controller 14 for the discharge operation in the fourth embodiment will be described with reference to FIG. 9 . The current measurement value calculator 33 calculates a combined current B flowing from the second connection terminal 15 to the second inverter 6 using the second current measurement value I2 and the second gate signal G2 to the second inverter 6. The PI controller 36 receives the deviation between the output from the current command value calculator 35 and the combined current B, which is the output from the current measurement value calculator 33. Based on this deviation, the PI controller 36 performs PI control. A gain is set so that the output of the PI controller 36 becomes the control phase difference φ [°]. The output of the PI controller 36, i.e., the control phase difference φ [°], is input to the PWM signal generator 38 via the phase shift controller 37. The duty ratio is also input to the PWM signal generator 38 from the duty ratio output unit 39. In this embodiment, the duty ratio is, for example, 0.5.

[0076] The PWM signal generator 38 generates a second gate signal G2 for switching the switching elements 6uH, 6vH, 6uL, and 6vL (see FIG. 2) associated with the U and V phases of the second inverter 6. To perform single-phase operation in the W phase of the second inverter 6, the switching elements 6wH and 6wL associated with the W phase are turned OFF. The PWM signal generator 38 also generates a first gate signal G1 for switching the switching elements 5uH, 5uL, 5vH, and 5vL associated with the U and V phases of the first inverter 5. The first gate signal G1 is generated relative to the second gate signal G2 so that a control phase difference φ [°] occurs between the reference phase and the control phase, as shown in FIGS. 12 and 13 . To perform single-phase operation in the W phase of the first inverter 5, the switching elements 5wH and 5wL associated with the W phase are turned OFF.

[0077] The first gate signal G1 and the second gate signal G2 are provided with dead time to prevent arm short-circuiting in the first inverter 5 and the second inverter 6. As an example, Fig. 14 shows the first gate signal G1 and the second gate signal G2 when the control phase difference φ is 90° and the duty ratio is 0.5. The description of the notation in Fig. 14 is omitted because it is the same as Fig. 10 .

[0078] The second gate signal G2 shown in Fig. 14 causes a current as shown in Fig. 15 to flow through the second winding 4 of the rotating machine 1. This causes power conversion between the second winding 4 and the first winding 3. The DC voltage of the battery 16 is input to the third inverter 10 via the third connection terminal 11. The controller 14 outputs a third gate signal G3 so that all switching elements of the third inverter 10 are turned OFF. This prevents a field current from flowing through the field winding 2.

[0079] Even if a current flows through the first winding 3 and the second winding 4, the field flux does not interlink with the first winding 3 and the second winding 4, so the rotational torque is small enough to prevent the rotation of the rotating shaft of the rotating machine 1. Furthermore, since the rotating machine 1 has a non-salient pole structure, in principle no reluctance torque is generated.

[0080] Effects of the Fourth Embodiment In this embodiment, by not passing a field current through the field winding 2 during charging and discharging operations, the field flux does not interlink with the first winding 3 and the second winding 4. Furthermore, since the rotating machine 1 has a non-salient pole structure, reluctance torque is not generated in principle. This makes it possible to reduce the rotational torque generated when the rotating machine 1 is used as an isolation transformer to a level that does not cause the rotating shaft to rotate. Therefore, vibrations and noise caused by the rotational torque during charging and discharging operations can be prevented.

[0081] Modification of the Fourth Embodiment During the charging and discharging operations, the switching elements 6wH, 6wL, 5wH, and 5wL associated with the W phase in FIG. 2 are turned off, but this is not limiting. For example, the switching elements 5uH, 5uL, 6uH, and 6uL associated with the U phase may be turned off, and the switching elements 5vH, 5vL, 5wH, 5wL, 6wH, 6wL, 6vH, and 6vL associated with the V and W phases may be switched on.

[0082] During charging of battery 16, control was performed to obtain the line voltage waveforms shown in Figures 7 and 8, but the same effect can be obtained if a phase difference is provided between the line voltage waveform of first winding 3 on the primary side and the line voltage waveform of second winding 4 on the secondary side. In other words, the line voltage waveforms shown in Figures 7 and 8 are merely examples and can be changed. Similarly, the line voltage waveforms shown in Figures 12 and 13 during discharging are also merely examples and can be changed.

[0083] The rotating machine 1 may have either an axial gap structure or a radial gap structure. In the charging operation and the discharging operation, the first gate signal G1 to the first inverter 5 and the second gate signal G2 to the second inverter 6 are outputted so as to perform single-phase operation, but the same effect can be obtained even if the first gate signal G1 and the second gate signal G2 are outputted so as to perform three-phase operation, because the field magnetic flux is not linked.

[0084] Based on the first current measurement value I1 and the first gate signal G1, a combined current A flowing from the first connection terminal 12 to the first inverter 5 was calculated. Based on the second current measurement value I2 and the second gate signal G2, a combined current B flowing from the second connection terminal 15 to the second inverter 6 was calculated. However, as shown in FIG. 16 , the same effect can be obtained by using the measurement value of the fourth current sensor 47 as combined current A and the measurement value of the fifth current sensor 48 as combined current B.

[0085] In addition, the modifications of the first to third embodiments may be applied to the fourth embodiment.

[0086] Fifth Embodiment Next, a fifth embodiment of the present disclosure will be described. The fifth embodiment has the same basic configuration as the fourth embodiment. Therefore, the following mainly describes differences from the fourth embodiment, and the same components are denoted by the same reference numerals and will not be described again. The overall configuration of the charging system 100 in the fifth embodiment is the same as that shown in FIG. 1. The rotating machine 1 in the fifth embodiment has a salient pole structure, which generates reluctance torque and sets the winding phase angle between the first winding 3 and the second winding 4 to 30°. Furthermore, with regard to the configuration of the controller 14, the control of the currents flowing through the first winding 3 and the second winding 4 will be described using FIG. 9, and the current flowing through the field winding will be described using FIG. 4.

[0087] Charging Operation in Embodiment 5 The DC voltage input to the first connection terminal 12 is converted into power by the first inverter 5 and the second inverter 6. At this time, the controller 14 outputs a first gate signal G1 to the first inverter 5 and a second gate signal G2 to the second inverter 6 so as to obtain the line voltage waveforms shown in FIGS.

[0088] Here, in the charging operation of the battery 16 from the DC power source 101 connected to the first connection terminal 12, the first inverter 5 is set as the reference phase and the second inverter 6 is set as the control phase. The aforementioned control phase difference φ [°] can be operated within a range from −180° to +180°. Changing the control phase difference φ [°] changes the current value and, therefore, the transmission power. That is, the controller 14 controls the current command values ​​for the first winding 3 and the second winding 4 in the first and second inverters 5 and 6 to change the control phase difference, thereby controlling the transmission power in the power conversion from the first inverter 5 to the second inverter 6. The controller 14 may also control the current command values ​​so that the average value of point 41 in FIG. 7 (the line voltage of the first inverter 5) and the average value of point 42 in FIG. 8 (the line voltage of the second inverter 6) both become zero. The rotor position of the rotating machine 1 is defined as 0°, where the magnetic flux linking the U-phase winding 3u of the first winding 3 is at a maximum when a field current is applied. However, power conversion may be started from any rotor position.

[0089] The control of the controller 14 related to the charging operation of the fifth embodiment will be described with reference to FIG. 9 . The controller 14 according to the fifth embodiment includes a current measurement value calculator 33, a current command value calculator 35, a PI controller 36, a phase shift controller 37, a PWM signal generator 38, and a duty ratio output unit 39. The first current measurement value I1 is input to the current measurement value calculator 33. The current measurement value calculator 33 calculates a combined current A flowing from the first connection terminal 12 to the first inverter 5 using the first current measurement value I1 and a first gate signal G1 output to the first inverter 5.

[0090] The PI controller 36 receives an input of the deviation between the output from the current command value calculator 35 and the composite current A, which is the output from the current measurement value calculator 33. Based on this deviation, the PI controller 36 performs PI control. A gain is set so that the output of the PI controller 36 becomes the control phase difference φ [°]. The output of the PI controller 36, i.e., the control phase difference φ [°], is input to a PWM signal generator 38 via a phase shift controller 37. A duty ratio output unit 39 also inputs a duty ratio to the PWM signal generator 38. In this embodiment, the duty ratio is, for example, 0.5.

[0091] The PWM signal generator 38 generates a first gate signal G1 for switching the switching elements 5uH, 5vH, 5uL, and 5vL (see FIG. 2) associated with the U and V phases of the first inverter 5. To perform single-phase operation in the W phase of the first inverter 5, the switching elements 5wH and 5wL associated with the W phase are turned OFF. The PWM signal generator 38 also generates a second gate signal G2 for switching the switching elements 6uH, 6uL, 6vH, and 6vL associated with the U and V phases of the second inverter 6. The second gate signal G2 is generated relative to the first gate signal G1 so as to generate a control phase difference φ [°] between the reference phase and the control phase, as shown in FIGS. 7 and 8 . To perform single-phase operation in the W phase of the second inverter 6, the switching elements 6wH and 6wL associated with the W phase are turned OFF.

[0092] The first gate signal G1 and the second gate signal G2 are provided with dead times to prevent arm short circuits in the first inverter 5 and the second inverter 6. As an example, FIG. 10 shows the first gate signal G1 and the second gate signal G2 when the control phase difference φ is 90° and the duty ratio is 0.5. The switching elements 5wH, 5wL, 5wH, and 6wL related to the W phases of the first inverter 5 and the second inverter are all OFF, and therefore are omitted from FIG. 10 . In FIG. 10 , the horizontal axis represents time. In FIG. 10 , time periods marked with a symbol such as "5uL" indicate that the corresponding switching element 5uL is ON, and time periods without a symbol indicate that the switching element is OFF.

[0093] The first gate signal G1 shown in Fig. 10 causes a current as shown in Fig. 11 to flow through the first winding 3 of the rotating machine 1. This causes power conversion between the first winding 3 and the second winding 4. The charging operation will be described below with reference to Fig. 4. The torque estimator 24 calculates a torque estimate based on the first current measurement value I1 and the second current measurement value I2. Specifically, the torque estimator 24 performs the calculation based on the following equations (1) to (5).

[0094]

[0095] In equations (1) to (5), the symbols are defined as follows: ｍ …Torque estimate τ ｆ１ …1st group electromagnet torque τ ｒ１ …First group reluctance torque τ ｆ２ …Two-group electromagnet torque τ ｒ２ …2nd group reluctance torque M ｗ ...mutual inductance between the first winding 3 and the second winding 4 and the field winding 2 P ｍ ...Number of pole pairs i ｆ …field current i ｕ１ ...phase current i flowing through the U-phase of the first winding 3 ｖ１ ...phase current i flowing through the V phase of the first winding 3 ｗ１ ...phase current i flowing through the W phase of the first winding 3 ｕ２ ...phase current i flowing through the U-phase of the second winding 4 ｖ２ ...phase current i flowing through the V phase of the second winding 4 ｗ２...phase current M flowing through the W phase of the second winding 4 ｒ …Mutual inductance between windings θ ｒｅ …Rotor position a ｕ２ ...Phase angle from the U-phase of the first winding 3 to the U-phase of the second winding 4 a ｖ２ ...phase angle from the U phase of the first winding 3 to the V phase of the second winding 4 a ｗ２ ...phase angle from the U-phase of the first winding 3 to the W-phase of the second winding 4

[0096] The torque estimation value τ, which is the output value of the torque estimator 24 ｍ is input to the field current command value calculator 25. The field current command value calculator 25 calculates the field current i as a field current command value based on the following equation (6): ｆ Calculate the following.

[0097]

[0098] The field current i calculated by the field current command value calculator 25 ｆ and the third current measurement value I3 measured by the third current sensor 9 is input to the PI controller 26. Based on this deviation, the PI controller 26 performs PI control.

[0099] In this embodiment, a field current is passed through the field winding 2 so as to cancel out the rotational torque generated in the first winding 3 and the second winding 4. For this purpose, the crossover frequency of the loop transmission gain in the control system for the field current is set to a value higher than the crossover frequency of the loop transmission gain in the control system for the current flowing through the first winding 3 and the second winding 4.

[0100] As shown in Fig. 4, interference compensation is performed by adding the output value of the interference compensator 27 to the output value of the PI controller 26. The sum of the output value of the PI controller 26 and the output value of the interference compensator 27 is input to the comparator 28. A triangular wave carrier output from a carrier generator 29 is input to the comparator 28. The comparator 28 generates a basic gate signal by comparing the sum of the output value of the PI controller 26 and the output value of the interference compensator 27 with the triangular wave carrier. The basic gate signal generated by the comparator 28 is input to the dead time adder 30.

[0101] ​The dead time adder 30 adds dead time to the basic gate signal to prevent an arm short circuit in the third inverter 10. The dead time adder 30 outputs the third gate signal G3 generated in this manner to the third inverter 10. As a result, a field current flows from the third inverter 10 to the field winding 2. The rotational torque of the rotating machine 1, which is generated when the first winding 3 and the second winding 4 perform power conversion, is canceled out by the field current. Therefore, the rotational torque generated in the rotating machine 1 is small enough to prevent the rotating shaft from rotating.

[0102] Discharge operation in embodiment 5. DC power input from battery 16 to third connection terminal 11 is converted by second inverter 6 and first inverter 5. At this time, controller 14 outputs a first gate signal G1 to first inverter 5 and a second gate signal G2 to second inverter 5 so as to obtain the line voltage waveforms shown in FIGS.

[0103] Here, in the discharge operation from the battery 16 to the first connection terminal 12, the second inverter 6 is set as the reference phase and the first inverter 5 is set as the control phase. As in the charging operation, the phase difference between point 41 in Fig. 12 and point 42 in Fig. 13 is defined as the control phase difference φ [°]. The rotor position is also defined as in the charging operation.

[0104] The control of the controller 14 for the discharge operation in the fifth embodiment will be described with reference to FIG. 9 . The current measurement value calculator 33 calculates a combined current B flowing from the second connection terminal 15 to the second inverter 6 using the second current measurement value I2 and the second gate signal G2 to the second inverter 6. The PI controller 36 receives the deviation between the output from the current command value calculator 35 and the combined current B, which is the output from the current measurement value calculator 33. Based on this deviation, the PI controller 36 performs PI control. A gain is set so that the output of the PI controller 36 becomes the control phase difference φ [°]. The output of the PI controller 36, i.e., the control phase difference φ [°], is input to the PWM signal generator 38 via the phase shift controller 37. The duty ratio is also input to the PWM signal generator 38 from the duty ratio output unit 39. In this embodiment, the duty ratio is, for example, 0.5.

[0105] The PWM signal generator 38 generates a second gate signal G2 for switching the switching elements 6uH, 6vH, 6uL, and 6vL (see FIG. 2) associated with the U and V phases of the second inverter 6. To perform single-phase operation in the W phase of the second inverter 6, the switching elements 6wH and 6wL associated with the W phase are turned OFF. The PWM signal generator 38 also generates a first gate signal G1 for switching the switching elements 5uH, 5uL, 5vH, and 5vL associated with the U and V phases of the first inverter 5. The first gate signal G1 is generated relative to the second gate signal G2 so that a control phase difference φ [°] occurs between the reference phase and the control phase, as shown in FIGS. 12 and 13 . To perform single-phase operation in the W phase of the first inverter 5, the switching elements 5wH and 5wL associated with the W phase are turned OFF.

[0106] The first gate signal G1 and the second gate signal G2 are provided with dead time to prevent arm short-circuiting in the first inverter 5 and the second inverter 6. As an example, Fig. 14 shows the first gate signal G1 and the second gate signal G2 when the control phase difference φ is 90° and the duty ratio is 0.5. The description of the notation in Fig. 14 is omitted because it is the same as Fig. 10 .

[0107] 14 causes a current as shown in FIG. 15 to flow through the second winding 4 of the rotating machine 1. As a result, power conversion is performed between the second winding 4 and the first winding 3.

[0108] The first gate signal G1 shown in Fig. 10 causes a current as shown in Fig. 11 to flow through the first winding 3 of the rotating machine 1. This causes power conversion between the first winding 3 and the second winding 4. The charging operation will be described below with reference to Fig. 4. The torque estimator 24 calculates a torque estimate based on the first current measurement value I1 and the second current measurement value I2. Specifically, the torque estimator 24 performs the calculation based on the above-mentioned equations (1) to (5).

[0109] The torque estimation value τ, which is the output value of the torque estimator 24 ｍis input to the field current command value calculator 25. The field current command value calculator 25 calculates the field current i as the field current command value based on the above-mentioned equation (6). ｆ Calculate the following.

[0110] The deviation between the field current if calculated by the field current command value calculator 25 and the third current measurement value I3 measured by the third current sensor 9 is input to the PI controller 26. Based on this deviation, the PI controller 26 performs PI control.

[0111] In this embodiment, a field current is passed through the field winding 2 so as to cancel out the rotational torque generated in the first winding 3 and the second winding 4. For this purpose, the crossover frequency of the loop transmission gain in the control system for the field current is set to a value higher than the crossover frequency of the loop transmission gain in the control system for the current flowing through the first winding 3 and the second winding 4.

[0112] As shown in Fig. 4, interference compensation is performed by adding the output value of the interference compensator 27 to the output value of the PI controller 26. The sum of the output value of the PI controller 26 and the output value of the interference compensator 27 is input to the comparator 28. A triangular wave carrier output from a carrier generator 29 is input to the comparator 28. The comparator 28 generates a basic gate signal by comparing the sum of the output value of the PI controller 26 and the output value of the interference compensator 27 with the triangular wave carrier. The basic gate signal generated by the comparator 28 is input to the dead time adder 30.

[0113] The dead time adder 30 adds dead time to the basic gate signal to prevent an arm short circuit in the third inverter 10. The dead time adder 30 outputs the third gate signal G3 generated in this manner to the third inverter 10. As a result, a field current flows from the third inverter 10 to the field winding 2. The rotational torque of the rotating machine 1, which is generated when the first winding 3 and the second winding 4 perform power conversion, is canceled out by the field current. Therefore, the rotational torque generated in the rotating machine 1 is small enough to prevent the rotating shaft from rotating.

[0114] According to this embodiment, when the rotating machine 1 is used as an isolation transformer, a field current is passed through the rotating machine 1 so as to cancel out the reluctance torque generated by the first winding 3 and the second winding 4. This makes it possible to prevent vibrations and noise caused by the rotational torque. The modifications described in the first to fourth embodiments may also be applied to this embodiment.

[0115] Sixth Embodiment Next, a sixth embodiment of the present disclosure will be described. The sixth embodiment has the same basic configuration as the fourth embodiment. Therefore, the following mainly describes the differences from the fourth embodiment, and the same components are denoted by the same reference numerals and will not be described again. The overall configuration of the charging system 100 in the sixth embodiment is the same as that shown in FIG. 1. In the sixth embodiment, as shown in FIG. 5, the first winding 3 and the second winding 4 are arranged radially side by side in the same slot (tooth opening). Therefore, the winding phase difference is 0°. The sixth embodiment also differs from the first embodiment in that the rotating machine 1 has a saliency and generates reluctance torque.

[0116] Charging Operation of Embodiment 6. The following describes the charging operation, focusing on differences from Embodiment 4. The rotor position of the rotating machine 1 is defined as 0°, where the magnetic flux linking the U-phase winding 3u of the first winding 3 is maximized when a field current is applied. In this embodiment, the rotor position is determined by applying current to the first winding 3 and the second winding 4 at the start of power conversion so that the rotor position is 60°. In this state, the controller 14 outputs the first gate signal G1 and the second gate signal G2 to turn off the switching elements 5wH, 5wL, 6wH, and 6wL, thereby performing single-phase drive. As a result, based on equations (3) and (5), the reluctance torque generated during power conversion is sufficiently small to the extent that the rotating shaft of the rotating machine 1 does not rotate. The same effect as when the rotor position is 60° can be achieved even if the rotor position at the start of power conversion is 150°, 240°, or 330°.

[0117] In the discharging operation, as in the charging operation, current is passed through the first winding 3 and the second winding 4 to determine the rotor position at 60° at the start of power conversion. The same effect as when the rotor position at the start of power conversion is 60° can be obtained whether the rotor position is 150°, 240°, or 330°. Other controls are the same as in the charging operation except that the direction of the current is reversed, and therefore will not be described here.

[0118] As described above, the charging device 13 according to the sixth embodiment includes the first current sensor 7 that measures the current flowing through the first winding 3, the second current sensor 8 that measures the current flowing through the second winding 4, and the third current sensor 9 that measures the field current flowing through the field winding 2. The controller 14 is configured to output a first gate signal G1 that controls the first inverter 5, a second gate signal G2 that controls the second inverter 6, and a third gate signal G3 that controls the third inverter 10, based on the first current measurement value I1 measured by the first current sensor 7, the second current measurement value I2 measured by the second current sensor 8, and the third current measurement value I3 measured by the third current sensor 9. The rotating machine 1 has a salient pole. When power conversion is performed between the first inverter 5 and the second inverter 6, the controller 14 outputs a first gate signal G1 and a second gate signal G2 to energize two of the three phases (U, V, W) of the first winding 3 and the second winding 4 and to open the remaining phase. The rotor position of the rotating machine 1 is defined as 0°, where the U-phase flux linkage is maximized when a field current is applied. The controller 14 sets the rotor position when starting power conversion between the first winding 3 and the second winding 4 to an angle shifted by an integer multiple of 90° from the phase angle of the winding between the two energized phases. Note that the term "integer" includes zero, and "an angle shifted by zero times 90° from the phase angle of the winding between the two energized phases" is synonymous with the phase angle of the winding between the two energized phases.

[0119] Effects of the Sixth Embodiment According to the sixth embodiment, when the rotating machine 1 is used as an isolation transformer, the switching elements 5wH, 5wL, 6wH, and 6wL are turned OFF for single-phase drive, and power conversion is started from the rotor position of 60°, thereby suppressing the reluctance torque generated by the first winding 3 and the second winding 4. This makes it possible to prevent vibrations and noise caused by reluctance torque. Furthermore, while the fifth embodiment requires that a field current be passed through to cancel out the reluctance torque, the present embodiment does not require passing current through the field winding, thereby reducing copper loss due to the field current.

[0120] Modification of Sixth Embodiment In the above description, the switching elements 6wH, 6wL, 5wH, and 5wL related to the W phase are turned OFF during charging and discharging. However, this is not limited to this, and the switching elements 5vH, 5vL, 6vH, and 6vL related to the V phase may be turned OFF, and the switching elements 5uH, 5uL, 5wH, 5wL, 6uH, 6uL, 6wH, and 6wL related to the U and W phases may be switched. In this case, the rotor position when power conversion starts is set to one of 30°, 120°, 210°, and 300°.

[0121] Alternatively, during charging and discharging, the switching elements 6uH, 6uL, 5uH, and 5uL related to the U phase may be turned off, and the switching elements 5vH, 5vL, 5wH, 5wL, 6vH, 6vL, 6wH, and 6wL related to the V and W phases may be switched. In this case, the rotor position when power conversion starts is set to any one of 0°, 90°, 180°, and 270°.

[0122] The relationship between the energized phase and the rotor position at the start of power conversion is shown in FIG. 17 . That is, when energizing the U and V phases, the rotor position at the start of power conversion is set to one of 60°, 150°, 240°, and 330°. When energizing the V and W phases, the rotor position at the start of power conversion is set to one of 0°, 90°, 180°, and 270°. When energizing the W and U phases, the rotor position at the start of power conversion is set to one of 30°, 120°, 210°, and 300°. Note that although the rotor position is determined based on the energized phase here, the energized phase may be selected based on the rotor position instead. When the rotor position is 55°, the combination in which the angle shifted ±90° from the rotor position is closest to the phase angle of the winding between the two energized phases is the combination in which the U and V phases are energized, and therefore the U and V phases should be energized. That is, in the charging operation, the two conduction phases are selected so that the phase angle of the winding between the two conduction phases has a value closest to the angle obtained by adding 90°×N (N is an integer) to the angle of the rotor position. In addition, the modified examples described in the first embodiment and the like may be applied to the sixth embodiment.

[0123] Seventh Embodiment Next, a seventh embodiment of the present disclosure will be described. The seventh embodiment has the same basic configuration as the fifth embodiment. Therefore, the following mainly describes the differences from the fifth embodiment, and the same components are denoted by the same reference numerals and will not be described again. The overall configuration of the charging system 100 in the seventh embodiment is the same as that shown in FIG. 1.

[0124] Charging Operation of Embodiment 7 The following describes the charging operation, focusing on the differences from Embodiment 5. As shown in FIG. 4, the first current measurement value I1 and the second current measurement value I2 are input to the torque estimator 24. Here, the controller 14 selects an operation mode according to the flowchart of FIG. 18. The operation mode is selected for each control period. Here, the lower limit of torque at which the rotating shaft starts to rotate from a stopped state and the rotational speed does not become zero is defined as the static friction torque. The controller 14 calculates the torque estimation value τ ｍand the static friction torque, and based on the result, the operation mode I or the operation mode II is selected. More specifically, as shown in step S1 of FIG. 18, the torque estimation value τ ｍ is greater than the negative static friction torque and less than the positive static friction torque, the operation mode I is selected (step S2). Otherwise, the operation mode II is selected (step S3). ｍ The estimation method is as explained in the fifth embodiment.

[0125] The processing in operation mode I will be described below. The controller 14 outputs a third gate signal G3 to turn off all switching elements of the third inverter 10. This prevents field current from flowing through the field winding 2. Even if current flows through the first winding 3 and the second winding 4, field flux does not link the first winding 3 and the second winding 4, so the rotational torque is sufficiently small to prevent the rotating shaft from rotating. The controller 14 also starts power conversion when the rotor is at 60° and outputs a first gate signal G1 and a second gate signal G2 to turn off the switching elements 5wH, 5wL, 6wH, and 6wL. By operating the inverter in this single-phase manner, the reluctance torque is sufficiently small to prevent the rotating shaft from rotating, as expressed by equations (3) and (5).

[0126] The processing in the operation mode II will be described below. As shown in FIG. 4, the output of the torque estimator 24 (the torque estimation value τ ｍ ) is input to a field current command value calculator 25. The field current command value calculator 25 calculates a field current command value based on equation (6). A PI controller 26 performs PI control based on the deviation between the field current command value and the third current measurement value I3. As described in the second embodiment, a field current flows to the field winding 2 so that the rotational torque generated in the first winding 3 and the second winding 4 is canceled by the field winding 2. Therefore, the rotational torque generated in the rotating machine 1 is sufficiently small so that the rotating shaft does not rotate.

[0127] Discharge Operation of Embodiment 7 As with the charge operation, in the discharge operation, the controller 14 selects the operation mode in accordance with the flowchart of FIG. 18. Operation Mode I and Operation Mode II are similar to those in the charge operation, and therefore will not be described here. The modifications described in the first to sixth embodiments may also be applied to the seventh embodiment.

[0128] As described above, the charging device 13 according to the seventh embodiment includes the first current sensor 7 that measures the current flowing through the first winding 3 and the second current sensor 8 that measures the current flowing through the second winding 4. The controller 14 calculates a torque estimation value τ , which is an estimate of the rotational torque acting on the rotor of the rotating machine 1, based on the first current measurement value I1 measured by the first current sensor 7 and the second current measurement value I2 measured by the second current sensor 8. ｍ The controller 14 calculates the torque estimate τ ｍ If it is determined that the rotor is rotating based on the above, a field current is passed so as to cancel out the rotation torque, and if it is determined that the rotor is not rotating, the field current is not passed.

[0129] Advantages of the Seventh Embodiment According to the seventh embodiment, as shown in FIG. ｍ Based on the comparison result between the torque estimation value τ and the static friction torque, it is determined for each control period whether to select the operation mode I or II, i.e., whether to supply the field current. ｍ Even if the magnitude relationship between the torque and static friction torque changes, an appropriate operation mode is selected, thereby preventing vibration and noise.

[0130] Eighth Embodiment. Next, an eighth embodiment of the present disclosure will be described. FIG. 19 shows a configuration example of a charging system 100A according to the eighth embodiment. While the fourth embodiment uses a wound-field motor as the rotating machine 1, the eighth embodiment uses a permanent magnet field motor as the rotating machine 1. Therefore, the eighth embodiment differs from the fourth embodiment in that the field winding 2, which is the third winding, and the components connected to or associated with this third winding are omitted, and instead a permanent magnet M is provided. The rotating machine 1 also differs from the fourth embodiment in that it has a salient polarity and generates reluctance torque. The winding phase difference between the first winding 3 and the second winding 4 is 0 degrees. The eighth embodiment differs from the fourth embodiment in the field structure, and therefore the rotor position at which power conversion starts is different. Note that the permanent magnet M in FIG. 19 is merely a schematic representation. In an actual permanent magnet field motor, multiple permanent magnets M are arranged at intervals in the circumferential direction.

[0131] Charging Operation of Embodiment 8. The following describes the charging operation, focusing on differences from Embodiment 4. The rotor position of the rotating machine 1 is defined as 0° (reference angle) when the magnetic flux generated by the permanent magnets interlinks with a winding of one of the phases of the first winding 3, for example, the U-phase winding 3u, at a maximum. In this embodiment, the rotor position is determined by energizing each energized phase of the first winding 3 and the second winding 4 (in this example, windings 3u and 3v and windings 4u and 4v) so that the rotor position is 150° at the start of power conversion. The rotor position of 150° at the start of power conversion is obtained by adding 90° to the angle between the two energized phases (in this example, the difference between the angle of winding 3u from the reference angle and the angle of winding 3v from the reference angle, or the difference between the angle of winding 4u from the reference angle and the angle of winding 4v from the reference angle; hereinafter, referred to as the energized phase angle). In this state, the controller 14 outputs a first gate signal G1 and a second gate signal G2 to turn off the switching elements 5wH, 5wL, 6wH, and 6wL to open the remaining phases (windings 3w and 4w in this example), thereby performing single-phase drive. As a result, the reluctance torque inherent to the salient pole structure that occurs during power conversion becomes sufficiently small to prevent the rotating shaft of the rotating machine 1 from rotating. Note that even if the rotor position at the start of power conversion is set to 330°, the same effect as when it is set to 150° can be obtained. In other words, the rotor position at the start of power conversion should be set to (interphase angle + 90°) + 180° × N (N is an integer).

[0132] In the discharging operation, as in the charging operation, current is passed through the first winding 3 and the second winding 4 to determine the rotor position at the start of power conversion so that the rotor position is 150°. Even if the rotor position at the start of power conversion is 330°, the same effect as in the case of 150° can be obtained. Other control of the discharging operation in this embodiment is the same as that of the charging operation except that the direction of the current is reversed, and therefore will not be described.

[0133] Ninth Embodiment Next, a ninth embodiment of the present disclosure will be described. The ninth embodiment has a similar configuration to the eighth embodiment, but differs from the eighth embodiment in the method of generating a current command value for suppressing rotational torque.

[0134] Charging Operation of Embodiment 9 The charging operation will be described below with reference to FIG. 9, focusing on the differences from Embodiment 8. In the controller 14, the current command value calculator 35 is set in advance as a constant the static friction torque of the rotating machine 1. The current command value calculator 35 generates a current command value so that the drive torque generated for the rotating machine 1 when current is passed through is equal to or less than the static friction torque. Other operations are the same as those described above. As a result, by making the static friction torque greater than the drive torque, the drive torque that can be generated is such that the rotating machine 1 does not rotate.

[0135] In the discharging operation, as in the charging operation, the current command value calculator 35 generates a current command value so that the static friction torque is greater than the driving torque. The other points are the same as in the eighth embodiment.

[0136] Tenth Embodiment Next, differences from the eighth embodiment of the present disclosure will be mainly described with reference to FIG. 9 . Although the rotor position of the rotating machine 1 is not shown, the rotor position is measured by a resolver or an encoder. As the rotor position of the rotating machine 1, a position closest to the rotor position at the start of power conversion described in the eighth embodiment (the rotor stop position based on the reference angle) is selected, and each phase current command value in the controller 14 is generated so that the rotor is positioned at the selected position. Other operations are the same as those described above.

[0137] In the discharging operation, the rotor position is measured and the rotor position at the start of power conversion is selected, just like in the charging operation.

[0138] Note that a program for realizing the functions of the controller 14 described in the first to tenth embodiments may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to perform the processing of the controller 14. The term "computer system" here includes hardware such as an OS and peripheral devices.

[0139] Furthermore, "computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within computer systems that serve as servers or clients. The programs may also be designed to realize some of the aforementioned functions, or may be capable of realizing the aforementioned functions in combination with programs already stored in the computer system. The programs may also be stored on a designated server, and distributed (e.g., downloaded) via communication lines in response to requests from other devices.

[0140] Furthermore, some or all of the functions of the controller 14 may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each function may be implemented as a processor individually, or some or all of the functions may be integrated into a processor. The integrated circuit method is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

[0141] Various aspects of the present disclosure are summarized below as appendices.

[0142] (Supplementary Note 1) A charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a field winding; a first inverter connected to the first winding; a second inverter connected to the second winding; a third inverter connected to the field winding; and a controller that outputs a gate signal to the third inverter to control a field current flowing in the field winding, wherein in a charging operation, the first inverter converts a direct current into an alternating current and supplies it to the first winding; the second inverter converts the alternating current in the second winding, which is induced by the alternating current in the first winding, into a direct current and supplies it to the battery; and the controller controls the field current so that a rotating shaft of the rotating machine does not rotate.

[0143] (Supplementary Note 2) The charging device according to Supplementary Note 1, wherein the controller does not cause the field current to flow through the field winding when performing power conversion between the first inverter and the second inverter.

[0144] (Supplementary Note 3) The charging device according to Supplementary Note 1, wherein the controller, when performing power conversion between the first inverter and the second inverter, causes the field current to flow through the field winding so as to cancel out rotational torque generated by current flowing through the first winding and the second winding. (Supplementary Note 4) The charging device according to Supplementary Note 1, characterized in that the controller controls transmission power by changing a phase difference between the line voltage of the first inverter and the line voltage of the second inverter. (Supplementary Note 5) The charging device according to Supplementary Note 4, characterized in that the controller controls so that an average value of the line voltage of the first inverter and an average value of the line voltage of the second inverter both become zero.

[0145] (Supplementary Note 6) The charging device according to any one of Supplementary Notes 1 to 5, wherein the controller superimposes harmonic components on a command value of the current to be passed through the first winding.

[0146] (Appendix 7) The charging device according to any one of Appendices 1 to 5, wherein the rotating machine has stator teeth, the stator teeth have a plurality of tooth openings, and the first winding and the second winding are arranged inside the plurality of tooth openings, parallel to each other and aligned radially.

[0147] (Supplementary Note 8) The charging device according to Supplementary Note 3, wherein, in the controller, a loop transmission gain of a control system for the field current flowing through the field winding is higher than a loop transmission gain of a control system for the current flowing through the first winding and the second winding.

[0148] (Supplementary Note 9) A rotating machine includes a first current sensor that measures a current flowing through the first winding, a second current sensor that measures a current flowing through the second winding, and a third current sensor that measures the field current flowing through the field winding, wherein the controller is configured to output a first gate signal that controls the first inverter, a second gate signal that controls the second inverter, and a third gate signal that controls the third inverter based on a first current measurement value measured by the first current sensor, a second current measurement value measured by the second current sensor, and a third current measurement value measured by the third current sensor, wherein the controller is configured to output a first gate signal to the first inverter and a second gate signal to the second inverter, wherein the rotating machine has a salient pole, and wherein the controller outputs the first gate signal and the second gate signal so that two phases of the first winding and the second winding are energized phases and the remaining one phase is opened when power conversion is performed between the first inverter and the second inverter, the rotor position of the rotating machine is defined as 0°, where a U-phase flux linkage is maximized when the field current is applied; the controller sets the rotor position when starting power conversion between the first winding and the second winding to an angle that is an integer multiple of 90° from a phase angle of the winding between the two current-carrying phases; and does not apply the field current to the field winding while the power conversion is being performed.

[0149] (Supplementary Note 10) A charging device according to Supplementary Note 1, comprising: a first current sensor that measures a current flowing through the first winding; and a second current sensor that measures a current flowing through the second winding, wherein the controller calculates a torque estimation value that is an estimate of a rotational torque acting on a rotor of the rotating machine based on a first current measurement value by the first current sensor and a second current measurement value by the second current sensor, and the controller passes the field current so as to cancel out the rotational torque when it is determined based on the torque estimation value that the rotor is rotating, and does not pass the field current when it is determined that the rotor is not rotating. (Supplementary Note 11) The charging device according to Supplementary Note 2, wherein the controller is configured to output a first gate signal to the first inverter and a second gate signal to the second inverter, the rotating machine having a salient pole, the controller outputs the first gate signal and the second gate signal to set two phases of each of the first winding and the second winding as energized phases and open the remaining one phase of each when performing power conversion between the first inverter and the second inverter, and when a position at which magnetic flux linking with a winding of any phase of the first winding when the field current is applied is defined as 0° as a reference angle of a rotor position of the rotating machine, the controller sets the rotor position when starting power conversion between the first winding and the second winding to a position at an angle shifted by an integer multiple of 90° from the phase angle of the winding between the two energized phases. (Supplementary Note 12) The charging device according to Supplementary Note 2, wherein the controller is configured to output a first gate signal to the first inverter and a second gate signal to the second inverter, the rotating machine has a salient pole, the controller outputs the first gate signal and the second gate signal so that two phases of each of the first winding and the second winding are energized phases and the remaining one phase of each is open when performing power conversion between the first inverter and the second inverter, and the controller generates a current command value so that the drive torque is equal to or less than a static friction torque during the charging operation.(Supplementary Note 13) A charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a permanent magnet; a first inverter connected to the first winding; a second inverter connected to the second winding; and a controller that outputs a first gate signal to the first inverter to control a current flowing through the first winding and outputs a second gate signal to the second inverter to control a current flowing through the second winding, wherein the rotating machine has a salient pole, and the controller outputs the first gate signal and the second gate signal so as to set two phases of each of the first winding and the second winding as conducting phases and to open the remaining one phase of each of the first winding and the second winding in a charging operation for performing power conversion between the first inverter and the second inverter, a charging device in which, when a reference angle of a rotor position of the rotating machine is defined as 0°, the position at which magnetic flux linking any one of the phase windings of the first winding is maximum, the controller sets the rotor position when starting power conversion between the first winding and the second winding to a position shifted by ±90° with respect to the angle between the two current-carrying phases. (Supplementary Note 14) A charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a permanent magnet; a first inverter connected to the first winding; a second inverter connected to the second winding; and a controller that outputs a first gate signal to the first inverter to control a current flowing through the first winding and a second gate signal to the second inverter to control a current flowing through the second winding, wherein the rotating machine has a salient pole, and the controller outputs the first gate signal and the second gate signal to set two phases of each of the first winding and the second winding as conducting phases and open the remaining one phase of each, during a charging operation that performs power conversion between the first inverter and the second inverter, and the controller generates a current command value during the charging operation so that a drive torque is equal to or less than a static friction torque. (Supplementary Note 15) The charging device according to Supplementary Note 12 or 14, wherein during the charging operation, the two conducting phases are selected based on a rotor position of the rotating machine.(Supplementary Note 16) The charging device according to Supplementary Note 15, wherein, in the charging operation, the two current-carrying phases are selected such that a phase angle of a winding between the two current-carrying phases has a value closest to an angle obtained by adding a value of 90°×N (N is an integer) to an angle of a rotor position of the rotating machine.

[0150] REFERENCE SIGNS LIST 1...Rotating machine 2...Field winding 3...First winding 4...Second winding 5...First inverter 6...Second inverter 7...First current sensor 8...Second current sensor 9...Third current sensor 10...Third inverter 13...Charging device 14...Controller 16...Battery 31...Stator teeth 31A to 31F...Teeth openings G1...First gate signal G2...Second gate signal G3...Third gate signal I1...First current measurement value I2...Second current measurement value I3...Third current measurement value

Claims

1. A charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a field winding; a first inverter connected to the first winding; a second inverter connected to the second winding; a third inverter connected to the field winding; and a controller that outputs a gate signal to the third inverter to control a field current flowing in the field winding, wherein during charging operation, the first inverter converts DC current to AC current and supplies it to the first winding; the second inverter converts the AC current in the second winding, which is induced by the AC current in the first winding, into DC current and supplies it to the battery; and the controller controls the field current so that the rotating shaft of the rotating machine does not rotate.

2. The charging device according to claim 1, wherein the controller does not cause the field current to flow through the field winding when power conversion is performed between the first inverter and the second inverter.

3. The charging device of claim 1, wherein the controller, when performing power conversion between the first inverter and the second inverter, causes the field current to flow through the field winding so as to cancel out rotational torque generated by current flowing through the first winding and the second winding.

4. The charging device according to claim 1, wherein the controller controls the transmission power by changing the phase difference between the line voltage of the first inverter and the line voltage of the second inverter.

5. The charging device according to claim 4, wherein the controller controls the average value of the line voltage of the first inverter and the average value of the line voltage of the second inverter to be zero.

6. The charging device according to any one of claims 1 to 5, wherein the controller superimposes harmonic components on the command value of the current to be passed through the first winding.

7. A charging device according to any one of claims 1 to 5, wherein the rotating machine has stator teeth, the stator teeth have a plurality of tooth openings, and the first winding and the second winding are arranged inside the plurality of tooth openings, parallel to each other and aligned radially.

8. The charging device according to claim 3, wherein, within the controller, the open-loop transmission gain of the control system for the field current flowing through the field winding is higher than the open-loop transmission gain of the control system for the current flowing through the first winding and the second winding.

9. A rotating machine comprising a first current sensor that measures a current flowing through the first winding, a second current sensor that measures a current flowing through the second winding, and a third current sensor that measures the field current flowing through the field winding, wherein the controller is configured to output a first gate signal that controls the first inverter, a second gate signal that controls the second inverter, and a third gate signal that controls the third inverter based on a first current measurement value measured by the first current sensor, a second current measurement value measured by the second current sensor, and a third current measurement value measured by the third current sensor, wherein the controller is configured to output a first gate signal to the first inverter and a second gate signal to the second inverter, wherein the rotating machine has a salient pole, and wherein the controller outputs the first gate signal and the second gate signal so that two phases of the first winding and the second winding are energized phases and the remaining one phase is opened when power conversion is performed between the first inverter and the second inverter, 3. The charging device according to claim 2, wherein a rotor position of the rotating machine is defined as 0°, where a U-phase flux linkage is maximized when the field current is applied, and the controller sets the rotor position when starting power conversion between the first winding and the second winding to an angle that is an integer multiple of 90° from a phase angle of the winding between the two current-carrying phases.

10. A charging device as described in claim 1, comprising a first current sensor that measures the current flowing through the first winding, and a second current sensor that measures the current flowing through the second winding, wherein the controller calculates a torque estimation value that is an estimate of the rotational torque acting on the rotor of the rotating machine based on the first current measurement value by the first current sensor and the second current measurement value by the second current sensor, and wherein the controller passes the field current so as to cancel out the rotational torque if it determines, based on the torque estimation value, that the rotor is rotating, and does not pass the field current if it determines that the rotor is not rotating.

11. The charging device according to claim 2, wherein the controller is configured to output a first gate signal to the first inverter and a second gate signal to the second inverter, the rotating machine having a saliency, the controller outputs the first gate signal and the second gate signal so that two phases of each of the first winding and the second winding are energized and the remaining one phase of each is open when power conversion is performed between the first inverter and the second inverter, and when the reference angle of the rotor position of the rotating machine is defined as 0°, the position at which magnetic flux linking with any phase of the first winding when the field current is applied is maximized, the controller sets the rotor position when starting power conversion between the first winding and the second winding to a position shifted by an integer multiple of 90° from the phase angle of the winding between the two energized phases.

12. The charging device according to claim 2, wherein the controller is configured to output a first gate signal to the first inverter and a second gate signal to the second inverter, the rotating machine has a saliency, the controller outputs the first gate signal and the second gate signal so that two phases of each of the first winding and the second winding are energized phases and the remaining one phase of each is open when power conversion is performed between the first inverter and the second inverter, and the controller generates a current command value so that the drive torque is equal to or less than static friction torque during the charging operation.

13. A charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a permanent magnet; a first inverter connected to the first winding; a second inverter connected to the second winding; and a controller that outputs a first gate signal to the first inverter to control the current flowing through the first winding and outputs a second gate signal to the second inverter to control the current flowing through the second winding, wherein the rotating machine has a salient pole, and the controller outputs the first gate signal and the second gate signal so that two phases of each of the first winding and the second winding are energized phases and the remaining one phase of each is open during a charging operation in which power conversion is performed between the first inverter and the second inverter, a charging device in which, when a reference angle of a rotor position of the rotating machine is defined as 0°, the position at which magnetic flux linking any one of the phase windings of the first winding is maximum, the controller sets the rotor position when starting power conversion between the first winding and the second winding to a position shifted by ±90° with respect to the angle between the two current-carrying phases.

14. A charging device for charging a battery, comprising: a rotating machine having a first winding, a second winding, and a permanent magnet; a first inverter connected to the first winding; a second inverter connected to the second winding; and a controller that outputs a first gate signal to the first inverter to control the current flowing in the first winding and a second gate signal to the second inverter to control the current flowing in the second winding, wherein the rotating machine has salient polarity; and during a charging operation in which power is converted between the first inverter and the second inverter, the controller outputs the first gate signal and the second gate signal so that two phases of each of the first winding and the second winding are energized phases and the remaining one phase of each is open; and during the charging operation, the controller generates a current command value so that the drive torque is equal to or less than static friction torque.

15. The charging device according to claim 12 or 14, wherein, in the charging operation, the two current-carrying phases are selected based on a rotor position of the rotating machine.

16. The charging device of claim 15, wherein, during the charging operation, the two current-carrying phases are selected so that the winding phase angle between the two current-carrying phases has a value closest to an angle obtained by adding 90° × N (N is an integer) to the rotor position angle of the rotating machine.

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