Rotating electric machine drive circuit, rotating electric machine system, and method for controlling rotating electric machine

Abstract

In a memory motor having a field winding in the rotor, it is possible to reduce the voltage required for magnetization operation. According to an embodiment, a rotary electric machine drive circuit 200 includes a three-phase inverter 221 that converts DC power from a DC power supply into three-phase AC power, and a controller 215 that controls the three-phase inverter 221. When the q-axis is defined as the direction in phase with the no-load induced voltage and the d-axis is defined as the direction of a phase that lags behind the q-axis by 90 electrical degrees, the field current generated by the three-phase inverter 221 includes a d-axis current that flows in the negative direction with respect to the d-axis direction.

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine drive circuit, a rotating electric machine system, and a method for controlling a rotating electric machine. [Background technology]

[0002] In recent years, interior permanent magnet synchronous motors have been widely adopted in electric drive systems for mobile vehicles due to their compact size and high efficiency. To achieve even higher efficiency, variable magnetic flux motors (memory motors) are known, which instantaneously apply a magnetic field to the magnet to actively change the magnetization state. From the perspective of high motor efficiency, high magnetic force is desirable at low speeds and low magnetic force at high speeds, and variable magnetic flux is a technology that solves this trade-off problem.

[0003] Magnets that change their magnetic state (hereafter referred to as variable magnetic force magnets) use magnets with low coercivity, but are designed to have a certain degree of demagnetization resistance to prevent unintended demagnetization during load operation. However, this means that a larger magnetomotive force is required to actively control the magnetic state. Therefore, in order to change the magnetic state of a variable magnetic force magnet, it is necessary to pass a large instantaneous current (hereafter referred to as magnetizing current) to apply an external magnetic field to the variable magnet.

[0004] Known methods for demagnetizing variable coercive force magnets include using the armature current to generate a magnetizing current, or providing a field winding in the rotor to generate a magnetizing current independent of the armature current. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5624284 [Patent Document 2] Patent No. 6833907 Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned method of using the armature current to pass the magnetizing current has the following problems.

[0007] It is difficult to perform demagnetization during load operation. In other words, the rotor drive and demagnetization of the variable coercive force magnet must be performed by controlling the same armature current. In particular, the above-mentioned prior art requires the passage of a magnetizing current that is much larger than the current used in normal load operation. Therefore, in order to obtain the desired magnetizing current, the rotating electric machine must be operated in a state other than under load.

[0008] Furthermore, it is difficult to achieve both a wide variable flux range within the inverter's allowable current and prevention of demagnetization during load operation. Furthermore, increasing the number of turns of the armature winding instead of reducing the conductor cross-sectional area can increase the magnetomotive force for demagnetization while maintaining the inverter current. However, this significantly increases the electrical resistance of the armature winding, and even if the variable flux performance improves, the loss caused by the winding increases, preventing the benefit of higher efficiency. Specifically, the first point is that a wide variable flux range requires a low demagnetization resistance of the variable coercivity magnet. Meanwhile, the second point is that the variable coercivity magnet must be able to withstand the opposing magnetic field that acts on it during load operation. These two points are mutually exclusive, making it difficult to achieve both.

[0009] Furthermore, in the method of demagnetizing using the armature current, the number of turns is designed to be small and the cross-sectional area of ​​the conductor per turn is large, taking into account that the armature winding is continuously energized. Because the magnetomotive force of the winding is proportional to the product of the number of turns and the current, in order to generate a strong magnetomotive force for demagnetization, it is necessary to pass an extremely large armature current as the magnetizing current, which poses the problem of a large load on the inverter elements or requiring an increase in inverter capacity.

[0010] In contrast, in the method of installing a field winding inside the rotor, the field winding is specialized for the instantaneous current supply for demagnetization, and by designing it with a very large number of turns and a small conductor cross-sectional area per turn, it is possible to obtain sufficient magnetomotive force even with a relatively small field current, thereby solving the problem of the aforementioned magnetizing current becoming enormous.

[0011] Furthermore, the above-mentioned method of providing a field winding in the rotor and passing a magnetizing current independently of the armature current has the following problems.

[0012] On the other hand, even with a method of providing a field winding in the rotor, the difficulty of magnetization at high rotational speeds remains. Typically, when magnetizing a memory motor, a magnetizing current is applied in a direction that strengthens the magnetic force of the variable magnet. During the magnetization operation, the magnetic force of the variable magnet is stronger than after magnetization, i.e., when the magnetization current has finished flowing. Therefore, during the magnetization operation, the magnetic flux resulting from the magnet and the magnetizing current interlinks with the armature winding, requiring a high voltage for the magnetization operation. Meanwhile, in a rotating electric machine drive circuit configuration without a boost function, the magnetization operation must be performed under the constraints of a fixed voltage source. As a result, magnetization cannot be performed at high rotational speeds due to voltage limitations.

[0013] From the perspective of improving efficiency under operating conditions where the motor is operated frequently (low speed, high load, high speed, light load), it is desirable to weaken the magnetization state in the high speed range. However, since a high load may be required even in the high speed range at low frequency, magnetization operation in the high speed range is also necessary from the perspective of achieving maximum motor performance.

[0014] The problem to be solved by the present invention is to provide a rotating electric machine drive circuit, a rotating electric machine system, and a method for controlling a rotating electric machine that are capable of reducing the voltage required for magnetization operation in a memory motor having a field winding in the rotor. [Means for solving the problem]

[0015] In order to achieve the above-mentioned object, a rotary electric machine drive circuit according to an embodiment of the present invention is a rotary electric machine drive circuit comprising a three-phase inverter that converts DC power from a DC power source into three-phase AC power, and a controller that controls the three-phase inverter, characterized in that, when the q-axis is in the same phase as the no-load induced voltage and the d-axis is in the phase direction that is 90 degrees behind the q-axis, the field current generated in the three-phase inverter by the controller includes a d-axis current in a negative direction with respect to the d-axis direction. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a partial horizontal cross-sectional view showing the configuration of a rotating electric machine to which a rotating electric machine drive circuit according to a first embodiment is applied. [Figure 2] 4 is a partial horizontal cross-sectional view showing a modified example of the configuration of a rotating electric machine that is the subject of the rotating electric machine drive circuit according to the first embodiment. FIG. [Figure 3] 1 is a circuit diagram showing a configuration of a rotating electrical machine system according to a first embodiment. [Figure 4] 3 is a flowchart showing the procedure of a control method for a rotating electric machine according to the first embodiment. FIG. [Figure 5] 4 is a graph showing a magnetizing operation pattern in the control method for the rotary electric machine according to the first embodiment. [Figure 6] 3 is an explanatory diagram conceptually illustrating the action of a field winding in the rotating electrical machine system according to the first embodiment. FIG. [Figure 7] FIG. 6 is a circuit diagram showing the configuration of a rotating electrical machine system according to a second embodiment. [Figure 8] 10 is a conceptual partial horizontal cross-sectional view showing an example of the arrangement of armature winding conductors in slots of a rotating electric machine targeted by a rotating electric machine drive circuit according to a second embodiment. FIG. [Figure 9] 10 is a conceptual partial horizontal cross-sectional view showing an example of a lamination state of an armature winding conductor in a slot of a rotating electric machine targeted by a rotating electric machine drive circuit according to a second embodiment. FIG. [Figure 10]10 is a conceptual partial horizontal cross-sectional view showing a comparative example for explaining the effect of an example of arrangement of armature winding conductors in slots of a rotating electric machine targeted by a rotating electric machine drive circuit according to a second embodiment. FIG. [Figure 11] FIG. 10 is a flowchart showing the procedure of a control method for a rotating electric machine according to a second embodiment. [Figure 12] 10 is a graph conceptually showing phase voltage waveforms in which a three-phase AC voltage and a zero-phase component are superimposed in a control method for a rotary electric machine according to a second embodiment. [Figure 13] 10 is a first conceptual graph illustrating a maximum value of a required voltage in a control method for a rotating electric machine according to a second embodiment. [Figure 14] 10 is a second conceptual graph illustrating the maximum value of the required voltage in the control method for the rotary electric machine according to the second embodiment. [Figure 15] 10 is a graph showing a magnetizing operation pattern in a control method for a rotary electric machine according to a second embodiment. [Figure 16] 10 is a graph showing the state of each current based on a rotating coordinate system during magnetization in the first case. [Figure 17] 10 is a graph showing the state of each current based on a stationary coordinate system during magnetization in the first case. [Figure 18] 10 is a graph showing the state of each current based on a rotating coordinate system after magnetization in the first case. [Figure 19] 10 is a graph showing the state of each current based on a stationary coordinate system after magnetization in the first case. [Figure 20] 10 is a graph showing the state of each current based on a rotating coordinate system during magnetization in a second case. [Figure 21] 10 is a graph showing the state of each current based on a stationary coordinate system during magnetization in a second case. [Figure 22] 10 is a graph showing the state of each current based on a rotating coordinate system during magnetization in a third case. [Figure 23] 10 is a graph showing the state of each current based on a stationary coordinate system during magnetization in a third case. [Figure 24]Table 1 shows the results of each case in which the magnetization operation was performed under conditions of low-speed, light-load operation. [Figure 25] Table 2 shows the results of each case in which the magnetization operation was performed under high-speed conditions. [Figure 26] FIG. 10 is a circuit diagram showing the configuration of a rotating electrical machine system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a rotating electric machine, a rotating electric machine system, and a method for controlling a rotating electric machine according to embodiments of the present invention will be described with reference to the drawings. Hereinafter, identical or similar parts will be denoted by common reference numerals, and duplicated explanations will be omitted.

[0018] [First embodiment]

[0019] <Configuration explanation> FIG. 1 is a partial horizontal cross-sectional view showing the configuration of a rotating electric machine 100 to which a rotating electric machine drive circuit according to the first embodiment is applied.

[0020] The rotating electric machine 100 has a rotor 110 and a stator 120. A sector-shaped portion enclosed by a dashed line indicates one magnetic pole 100p.

[0021] The rotor 110 has a rotor shaft 111, a rotor core 112 attached radially outside the rotor shaft 111, variable magnetic force magnets 113, a field winding 114, inner fixed magnetic force magnets 115, and outer fixed magnetic force magnets 116. The rotor shaft 111 is rotatably supported on both axial sides by bearings (not shown).

[0022] The inner fixed magnetic force magnet 115 is a conventionally used permanent magnet with a sufficiently large coercive force. On the other hand, the variable magnetic force magnet 113 is a permanent magnet with a smaller coercive force than the inner fixed magnetic force magnet 115, and the magnetization state is adjusted by the external magnetic field generated by the field winding 114. Both magnets are already magnetized.

[0023] Here, for convenience of explanation, directions will be defined. In a cross section perpendicular to the central axis of rotation CL of the rotor 110, the direction away from the central axis of rotation will be referred to as the radial direction. Note that the term radial direction does not limit the cross section of the rotor shaft 111 to a circular shape. Furthermore, the direction in which the central axis of rotation CL extends and the direction parallel to this will be referred to as the axial direction or rotation axis direction. Furthermore, the direction in which a target part in the rotor 110 moves while the rotor 110 is rotating will be referred to as the circumferential direction. Note that the radial direction, axial direction (rotation axis direction), and circumferential direction also include the opposite directions of their respective definitions.

[0024] The configuration of each magnetic pole 110a will be described below. Note that hereinafter, as the reference phase of the three-phase AC current, the q-axis is defined as the direction in phase with the no-load induced voltage generated in the three-phase armature winding 125 (FIG. 2) during forward rotation when no three-phase AC current is flowing through the armature winding 125. Also, the d-axis is defined as the phase direction that lags behind the q-axis by 90 electrical degrees. The direction of the d-axis (d-axis direction) is the same as the direction of the magnetic flux of the magnet when there is no load.

[0025] The variable magnetic force magnets 113 are arranged at the circumferential center of each magnetic pole. Field windings 114 are arranged on both circumferential sides of the variable magnetic force magnets 113. The field windings 114 function as single-phase field windings. The inner fixed magnetic force magnets 115 are arranged on the circumferential outside of each field winding.

[0026] In each magnetic pole 110a of the rotor core 112, an inner magnet storage outer flux barrier 112a, an inner magnet storage portion 112b, an inner magnet storage inner flux barrier 112c, and an inner bridge 112d are formed radially inward from one side of the rotor core surface 112s. Furthermore, from the inner bridge 112d to the other side of the rotor core surface 112s, the inner magnet storage portion inner flux barrier 112c, the inner magnet storage portion 112b, and the rotor core surface 112s are formed. These are arranged continuously and in a generally convex shape toward the central axis of rotation CL. This region is referred to as the first flux barrier band. Although the lead wire of the inner magnet storage portion 112b points to the inner fixed magnetic force magnet 115, this refers to the space where the inner fixed magnetic force magnet 115 is not present.

[0027] Additionally, on the radially inner side, from one side of the rotor core surface 112s, an outer magnet storage outer flux barrier 112e, an outer magnet storage portion 112f, an outer magnet storage inner flux barrier 112g, an outer bridge 112h, and an outer central flux barrier 112j are formed. Furthermore, from the outer central flux barrier 112j to the other side of the rotor core surface 112s, the outer bridge 112h, the outer magnet storage inner flux barrier 112g, the outer magnet storage portion 112f, and the outer magnet storage outer flux barrier 112e are formed. These are arranged continuously and in a generally convex shape toward the central axis of rotation CL. This region is referred to as the second flux barrier band. Although the lead wire of the outer magnet storage portion 112f points to the outer fixed magnetic force magnet 116, this refers to the space where the outer fixed magnetic force magnet 116 is not present.

[0028] In the following embodiment, the rotor 110 will be described as having both the variable magnetic force magnets 113 and the inner fixed magnetic force magnets 115, but it may also have only the variable magnetic force magnets 113 without the inner fixed magnetic force magnets 115. In addition, in the figure, of the two-layer flux barrier bands, the variable magnetic force magnets are loaded only in the flux barrier band on the inner diameter side, but it may also be configured so that the variable magnetic force magnets are loaded only in the flux barrier band on the outer diameter side, or in both flux barrier bands.

[0029] Fig. 2 is a partial horizontal cross-sectional view showing a modified configuration of the rotating electric machine 100 targeted by the rotating electric machine drive circuit according to the first embodiment. In the rotor 110a of the modified configuration shown in Fig. 2, a variable magnetic force magnet 113s is provided at the circumferential center of the second flux barrier band, instead of the outer central flux barrier 112j. In addition, a field winding 114s for adjusting the magnetization state of the variable magnetic force magnet 113s is provided adjacent to the variable magnetic force magnet 113s. Fig. 2 shows an example configuration in which variable magnetic force magnets are installed in both flux barrier bands.

[0030] 2, the field winding 114 for exciting the variable magnetic force magnet 113 of the first flux barrier band and the field winding 114s for exciting the variable magnetic force magnet 113s of the second flux barrier band are electrically connected in series. Alternatively, the field winding 114 and the field winding 114s are provided so as to be electrically connectable to each other.

[0031] The field winding 114 generates a magnetic field by means of a field winding current that adjusts the magnetization state of the variable magnetic force magnet 113. The magnetic field generated by the field winding current flowing through the field winding 114 is directed radially inward or radially outward depending on the flow of the field winding current in one or the opposite direction.

[0032] The field winding 114 is configured to form a coil using a conductor having a round cross section, but may also be configured to have conductors having a square cross section stacked in the radial direction.

[0033] The stator 120 has a stator core 121 disposed radially outside the rotor core 112, and a three-phase armature winding 125 (hereinafter referred to as the armature winding 125). Teeth 122 are formed on the inner surface of the stator core 121 at intervals in the circumferential direction. Adjacent teeth 122 form slots 122a. The stator core 121 has an annular yoke 123 formed on the radially outer side of the teeth 122. Adjacent teeth 122 form slots 122a. The armature winding 125 is disposed to pass through the slots 122a and is wound around the teeth 122. For ease of explanation of the slots 122a, the armature winding 125 within the slots 122a, which are indicated by lead lines, is not shown in FIGS. 1 and 2. The armature winding 125 is arranged to pass through the slot portion 122 a and is wound around the tooth portion 122 .

[0034] Fig. 3 is a circuit diagram showing the configuration of a rotating electric machine system 20 according to the first embodiment. The rotating electric machine system 20 includes a rotating electric machine 100 and a rotating electric machine drive circuit 200 for the rotating electric machine 100 (Figs. 1 and 2). Fig. 3 shows a power circuit including the rotating electric machine 100 (Figs. 1 and 2) and the rotating electric machine drive circuit 200 in the rotating electric machine system 20, and shows the armature winding 125 of the rotating electric machine 100.

[0035] The rotary electric machine drive circuit 200 has a first three-phase inverter 221 that supplies power to the armature winding 125, and a dedicated field winding circuit, such as a chopper circuit 32, that generates magnetic force for the variable magnetic force magnet 113. Note that the dedicated field winding circuit may be any other circuit as long as it supplies direct current for the field winding 114, but the following description will be given taking the chopper circuit 32 as an example.

[0036] The first three-phase inverter 221 uses an external DC power supply 1 as a power source and supplies AC power to the armature winding 125 of the rotating electrical machine 100 .

[0037] The three-phase inverter 210 is a full-bridge inverter circuit configured with a plurality of IGBTs (Insulated Gate Bipolar Transistors) 5. The three-phase inverter 210 receives DC power from a DC power supply 1 as input and supplies three-phase AC power to external connection terminals 131a, 131b, and 131c of the rotating electric machine 100. Note that the components are not limited to IGBTs, and other power semiconductors such as MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) may be used depending on the purpose.

[0038] The armature winding 125 has armature winding conductors, namely, a U-phase conductor 126u, a V-phase conductor 126v, and a W-phase conductor 126w, which are connected in parallel to one another. One end of the U-phase conductor 126u, the V-phase conductor 126v, and the W-phase conductor 126w is connected to external connection terminals 131a, 131b, and 131c, respectively. The other ends of the U-phase conductor 126u, the V-phase conductor 126v, and the W-phase conductor 126w are connected to one another at a neutral point 125n.

[0039] Chopper circuit 32, exemplified as a field winding-dedicated circuit for field winding 114, receives DC power from external DC power supply 1 as a power source to be passed through field winding 114. Chopper circuit 32 has field winding 114 and an H-bridge circuit made up of switching elements that supplies power to field winding 114. Note that the following description will be given taking IGBT 5 as an example of the switching elements.

[0040] A first end 114a of the field winding 114 is electrically connected or configured to be electrically connectable to one midpoint of the H-bridge circuit via a first slip ring 117a, and a second end 114b of the field winding 114 is electrically connected or configured to be electrically connectable to the other midpoint of the H-bridge circuit via a second slip ring 117b.

[0041] The controller 215 controls the gate voltages of the IGBTs 5 that constitute the three-phase inverter 210 and the chopper circuit 32. In other words, the controller 215 outputs command signals for turning on and off the IGBTs 5.

[0042] The controller 215 has an input unit 215a, a storage unit 215b, a calculation unit 215c, and an output unit 215d. Details of the controller 215 will be described later with reference to FIGS.

[0043] As described above, the rotating electric machine 100 includes the rotor 110 and the stator 120 .

[0044] <Explanation of action> 4 is a flowchart showing the procedure of the control method for the rotary electric machine according to the first embodiment, that is, the control procedure by the controller 215 of the rotary electric machine drive circuit 200.

[0045] For convenience of explanation, the procedure will be described taking as an example a case where the rotary electric machine 100 is a drive motor for a vehicle. For example, the procedure starts when the drive key for the vehicle is inserted.

[0046] First, the input unit 215a of the controller 215 receives magnetization condition data as external data (step S01). The magnetization condition data is data including magnetization conditions for changing the magnetic force of the variable magnetic force magnet 113 when switching between each operating state. The magnetization condition data received by the input unit 215a is stored in the storage unit 215b.

[0047] Next, the calculation unit 215c of the controller 215 determines whether or not it is necessary to switch the magnetic force of the variable magnetic force magnet 113 (step S02). The determination of whether or not to switch the magnetic force is made by receiving information relating to a change in the driving state, for example, when the vehicle starts moving or when a gear is changed. The information relating to a change in the driving state may be stored in the memory unit 215b as a table, for example, and the calculation unit 215c may make a determination by comparing it with the table. If it is not determined that a change in magnetic force is necessary (step S02 NO), the controller 215 remains in a standby state.

[0048] If it is determined that switching of the magnetic force is necessary (step S02: YES), the calculation unit 215c accesses the memory unit 215b and reads the magnetization conditions at the time of switching from the magnetization conditions at the time of each switching stored in the memory unit 215b (step S03).

[0049] The calculation unit 215c derives magnetization currents (field current and armature current) corresponding to the read magnetization conditions (step S04). The calculation unit 215c further derives gate voltages for each IGBT 5 for passing the magnetization current based on the derived magnetization current. If the voltage exceeds the voltage limit in the drive circuit, the calculation unit 215c corrects the magnetization current to take this into account and derives the voltage again. The output unit 215d outputs the results to the IGBTs 5 of the H-bridge of the chopper circuit 32 and the IGBTs 5 of the three-phase inverter 210.

[0050] Next, a magnetizing current is passed (step S05). In detail, first, the three-phase inverter 210 outputs the gate voltage of each IGBT 5 of the chopper circuit 32 derived by the calculation unit 215c for a predetermined time (magnetization time). The predetermined time here is the time required for the magnetization state of the variable magnetic force magnet 113 to change. Note that the above explanation has been given taking as an example a method of calculating and applying the voltage required to pass the magnetizing current in a feedforward manner, but in addition to this, a method of determining and applying a command voltage by combining feedback control based on the difference between a current command value and a current detection value may also be used.

[0051] Next, the calculation unit 215c determines whether or not the operation is to be stopped (step S06). That is, it determines whether or not information to the effect that the operation of the rotating electric machine 100 is to be stopped has been received. If it is not determined that the operation is to be stopped (step S06: NO), steps S02 to S06 are repeated. If it is determined that the operation is to be stopped (step S06: YES), the control is terminated.

[0052] 5 is a graph showing a magnetization operation pattern in the control method for a rotating electric machine according to the first embodiment. With respect to the magnetization operation during load operation, the field current, armature current, and armature voltage values ​​during and after magnetization are conceptually shown.

[0053] Regarding the field current, a field current of value if is passed through the field winding 114 during magnetization, and becomes zero after magnetization.

[0054] Regarding the armature current, the absolute value of the negative side of the d-axis current, which is the current element that generates magnetic flux, is larger during magnetization compared to after magnetization. Accordingly, the value of the q-axis current, which acts as a torque current, is smaller during magnetization compared to after magnetization. As a result, the armature voltage required for the magnetizing operation is reduced.

[0055] 6 is an explanatory diagram conceptually illustrating the action of the field winding in the rotating electric machine system according to the first embodiment. Fig. 6 shows adjacent magnetic poles P1 and P2. The solid arrows indicate the direction of the magnetic force of the inner fixed magnetic force magnet 115 and the outer fixed magnetic force magnet 116. The dashed arrows indicate the direction of the magnetic force of the variable magnetic force magnets 113 and 113a. The dashed arrows indicate the direction of the magnetic force generated by the armature current flowing through the armature winding 125.

[0056] 6, only the directions of the magnetic forces of the inner fixed magnetic force magnet 115 and the outer fixed magnetic force magnet 116 are fixed. In magnetic pole P1, the directions of the magnetic forces of the inner fixed magnetic force magnet 115 and the outer fixed magnetic force magnet 116 are both oriented such that the overall magnetic force faces radially outward. On the other hand, in magnetic pole P2, the directions of the magnetic forces of the inner fixed magnetic force magnet 115 and the outer fixed magnetic force magnet 116 are both oriented such that the overall magnetic force faces radially inward. Because adjacent magnetic poles have this relationship, a magnetic flux is formed that closes as a whole and passes through the stator core 121.

[0057] On the other hand, the direction of the magnetic force of variable magnetic force magnets 113 and 113a, indicated by the open dashed arrows, is variable depending on the direction of the current flowing through field windings 114 and 114s. Figure 6 shows a case where the direction of the magnetic force of variable magnetic force magnets 113 and 113a is oriented in the same direction as the direction of the magnetic force of inner fixed magnetic force magnet 115 and outer fixed magnetic force magnet 116.

[0058] Increasing the magnitude of the magnetic force of the variable magnetic force magnets 113 and 113a is referred to as magnetization. That is, in magnetic pole P1, magnetization occurs when the magnitude of the magnetic force directed radially outward of the variable magnetic force magnets 113 and 113a increases. On the other hand, in magnetic pole P2, magnetization occurs when the magnitude of the magnetic force directed radially inward of the variable magnetic force magnets 113 and 113a increases.

[0059] Furthermore, the direction of the magnetic force generated by the armature current flowing through the armature winding 125, indicated by the dashed arrow, is also variable depending on the armature current.

[0060] When the variable magnetic force magnets 113, 113a are magnetized, the magnetic force generated by the inner fixed magnetic force magnet 115, the outer fixed magnetic force magnet 116, and the variable magnetic force magnets 113, 113a and directed toward the stator core 121 reaches a maximum. As a result, the induced electromotive force induced in the armature winding 125 by the magnetic force of each permanent magnet in the rotor also reaches a maximum. If this induced electromotive force exceeds the power supply voltage of the DC power supply 1, it becomes difficult to control the current, which means that the intended magnetization operation cannot be performed.

[0061] 6, the direction of the magnetic force generated by the armature current flowing through the armature winding 125, indicated by the dashed arrows, is radially inward at magnetic pole P1 and radially outward at magnetic pole P2. That is, it is opposite to the direction of the magnetic forces generated by the inner fixed magnetic force magnet 115, the outer fixed magnetic force magnet 116, and the variable magnetic force magnets 113 and 113a and directed toward the stator core 121. That is, it is in a direction that reduces the value of the induced electromotive force induced in the armature winding 125 by the magnetic force of each permanent magnet in the rotor.

[0062] <Explanation of effect> As described above, the rotating electrical machine system 20 according to this embodiment has the following effects by providing the field winding 114 and simultaneously passing a positive field current and a negative d-axis current during the magnetizing operation.

[0063] (1) It is possible to separate the dq-axis current control of the armature winding 125 for load operation of the rotating electric machine 100 from the field winding current control for demagnetizing the variable magnetic force magnet 113. As a result, it is possible to change the magnetization state even during load operation of the rotating electric machine 100. (2) To address the problem of an increase in the induced electromotive force in the armature winding 125 due to the magnetization of the variable magnetic force magnet 113, a larger negative d-axis current is passed through the armature winding 125 than after magnetization, thereby reducing the voltage required for the magnetization operation.

[0064] [Second embodiment] FIG. 7 is a circuit diagram showing the configuration of a rotating electrical machine system 20a according to the second embodiment.

[0065] This embodiment is a modification of Embodiment 1. A rotating electric machine drive circuit 200a of a rotating electric machine system 20a according to this embodiment has a first three-phase inverter 221, a second three-phase inverter 222, and a controller 216.

[0066] In the rotating electric machine 100a of the rotating electric machine system 20a according to this embodiment, the armature winding 125 has two series of armature winding conductors: a first series of armature winding conductors 127 and a second series of armature winding conductors 128. The armature winding first series conductor 127 includes a first series U-phase conductor 127u, a first series V-phase conductor 127v, and a first series W-phase conductor 127w, one end of each of which is connected to external connection terminals 131a, 131b, and 131c. The armature winding first series conductor 127 is electrically connected or configured to be electrically connectable to the first three-phase inverter 221 via the external connection terminals 131a, 131b, and 131c. The other ends of the first series U-phase conductor 127u, the first series V-phase conductor 127v, and the first series W-phase conductor 127w are connected to one another at a neutral point 127n. The neutral point 127n functions as a first neutral point.

[0067] The second-series armature winding conductor 128 includes a second-series U-phase conductor 128u, a second-series V-phase conductor 128v, and a second-series W-phase conductor 128w, one end of each of which is connected to external connection terminals 132a, 132b, and 132c. The second-series armature winding conductor 128 is electrically connected or configured to be electrically connectable to the second three-phase inverter 222 via the external connection terminals 132a, 132b, and 132c. The other ends of the second-series U-phase conductor 128u, the second-series V-phase conductor 128v, and the second-series W-phase conductor 128w are connected to one another at a neutral point 128n. The neutral point 128n functions as a second neutral point.

[0068] A first end 114a of the field winding 114 is electrically connected to a neutral point 127n of the armature winding first series conductor 127 by a neutral point lead wire 127m via a first slip ring 117a, or is configured to be connectable to each other. Also, a second end 114b of the field winding 114 is electrically connected to a neutral point 128n outside the armature winding second series conductor 128 by a neutral point lead wire 128m via a second slip ring 117b, or is configured to be connectable to each other.

[0069] In the first embodiment, the voltage across the field winding 114 is generated by a chopper circuit 32 that receives power from a DC power supply 1. On the other hand, in the second embodiment, the field winding is connected between two three-phase inverters, and therefore the difference between the zero-phase voltages of the three-phase inverters becomes the voltage that passes the zero-phase current. For example, the first three-phase inverter 221 is controlled so that the zero-phase voltage is positive, and the second three-phase inverter 222 is controlled so that the zero-phase voltage is negative, thereby generating a zero-phase voltage difference.

[0070] The controller 216 has the same configuration as in the first embodiment, that is, an input unit 216a, a storage unit 216b, a calculation unit 216c, and an output unit 216d, but differs from the first embodiment in parts corresponding to the differences in configuration.

[0071] FIG. 8 is a conceptual partial horizontal cross-sectional view showing an example of the arrangement of armature winding conductors 126 in slots of a rotating electric machine 100 that is the subject of a rotating electric machine drive circuit according to the second embodiment.

[0072] A plurality of slots 122a are formed at intervals in the circumferential direction on a stator core inner peripheral surface 121x on the radially inner side of the stator core 121. The stator core inner peripheral surface 121x is cylindrical, but in Fig. 8, its cross section is simplified and shown as a straight line.

[0073] In each slot portion 122a, a U-phase conductor, a U-phase conductor, a V-phase conductor, a V-phase conductor, a W-phase conductor, and a W-phase conductor are arranged in a repeating pattern of six slots. Within each slot portion 122a, the U-phase conductor, the V-phase conductor, or the W-phase conductor is stacked in the radial direction.

[0074] Here, the U-phase conductor refers to the first-series U-phase conductor 127u or the second-series U-phase conductor 128u, the V-phase conductor refers to the first-series V-phase conductor 127v or the second-series V-phase conductor 128v, and the W-phase conductor refers to the first-series W-phase conductor 127w or the second-series W-phase conductor 128w.

[0075] 9 is a conceptual partial horizontal cross-sectional view showing an example of the lamination state of the armature winding conductors 126 in the slots 122a of the rotating electric machine 100 targeted by the rotating electric machine drive circuit according to the second embodiment. Fig. 9 shows the lamination state of the U-phase conductors in two adjacent slots 122a and the current flow direction when only a zero-phase current is flowing.

[0076] A plurality of U-phase conductors (four in FIG. 9) are stacked in each slot 122a. Furthermore, the same number (two) of first-series U-phase conductors 127u and second-series U-phase conductors 128u are alternately stacked in one slot 122a. The current flowing through the first-series U-phase conductor 127u is from the back to the front of the page, and the current flowing through the second-series U-phase conductor 128u is from the front to the back of the page, and these currents are opposite to each other in the direction of the rotation axis (direction parallel to the rotation axis).

[0077] The reason for this is that in FIG. 5, zero-phase current flows from one inverter to the other (for example, from neutral point 127n to neutral point 128n). As a result, the direction of the zero current is reversed between the two inverters, i.e., between the conductors of the two series. Meanwhile, although not shown in FIGS. 8 and 9, the direction of the three-phase AC current flowing through each series is the same in the first series U-phase conductor 127u and the second series U-phase conductor 128u. Therefore, during normal load operation, the two inverters control three-phase AC currents that are roughly in phase.

[0078] Furthermore, the stacking order within two adjacent slots 122a is reversed. That is, in the slot 122a on the left side of Fig. 9, the first series U-phase conductor 127u and the second series U-phase conductor 128u are stacked in this order from the inside in the radial direction, while in the slot 122a on the right side of Fig. 9, the second series U-phase conductor 128u and the first series U-phase conductor 127u are stacked in this order from the inside in the radial direction.

[0079] Fig. 10 is a conceptual partial horizontal cross-sectional view showing a comparative example for describing the effect of an example of arrangement of the armature winding conductors 126 in the slots 122a of the rotating electric machine 100 targeted by the rotating electric machine drive circuit according to the second embodiment. In the comparative example, only the first-series U-phase conductor 127u is laminated in the slot 122a on the left side of Fig. 10. Also, only the second-series U-phase conductor 128u is laminated in the slot 122a on the right side of Fig. 10. The currents in the U-phase conductors in two adjacent slots 122a flow in the same direction within each slot 122a, and the zero-phase current flowing through the first-series U-phase conductor 127u and the zero-phase current flowing through the second-series U-phase conductor 128u flow in opposite directions in the axial direction.

[0080] The dashed lines in FIG. 10 indicate the magnetic fields formed by the zero-phase current flowing through the U-phase conductors in each slot 122a. The magnetic field MF1 formed by the zero-phase current flowing through the first-series U-phase conductor 127u in the left slot 122a rotates counterclockwise. On the other hand, the magnetic field MF2 formed by the zero-phase current flowing through the second-series U-phase conductor 128u in the right slot 122a rotates clockwise. As a result, the magnetic fields MF1 and MF2 do not cancel each other out, and a magnetic field directed radially outward is generated between the two slots 122a. This can lead to a deterioration in transient response characteristics due to an increase in the inductance of the field winding or to unintended behavior due to local magnetic saturation.

[0081] In the rotating electric machine 100 according to this embodiment, the magnetic fields of the armature windings of the same phase housed in adjacent slots 122a cancel each other out, so this problem does not occur.

[0082] 11 is a flowchart showing the procedure of the control method for the rotary electric machine according to the second embodiment, that is, the control procedure by the controller 216 of the rotary electric machine drive circuit 200.

[0083] For convenience of explanation, the procedure will be described taking as an example a case where the rotary electric machine 100 is a drive motor for a vehicle. For example, the procedure starts when the drive key for the vehicle is inserted.

[0084] First, the input unit 216a of the controller 216 receives magnetization condition data as external data (step S01). The magnetization condition data is data including magnetization conditions for changing the magnetic force of the variable magnetic force magnet 113 when switching between each operating state. The magnetization condition data received by the input unit 216a is stored in the memory unit 216b.

[0085] Next, the calculation unit 216c of the controller 216 determines whether or not it is necessary to switch the magnetic force of the variable magnetic force magnet 113 (step S02). Note that even if a variable magnetic force magnet 113s is provided in addition to the variable magnetic force magnet 113, it is sufficient to simply read "variable magnetic force magnet 113" as "variable magnetic force magnet 113 and variable magnetic force magnet 113s." The decision to switch the magnetic force is made by receiving information related to a change in the driving state, such as when the vehicle starts moving or when a gear is changed. If it is not determined that a switch of the magnetic force is necessary (step S02 NO), the controller 216 remains in a standby state.

[0086] If it is determined that switching of the magnetic force is necessary (step S02 YES), the calculation unit 216c accesses the memory unit 216b and reads the magnetization conditions at the time of switching from the magnetization conditions at the time of each switching stored in the memory unit 216b (step S03).

[0087] The calculation unit 216c derives a zero-phase current corresponding to the read magnetization condition (step S04a). Based on the derived zero-phase current, the calculation unit 216c further derives a gate voltage of each IGBT 5 that superimposes the zero-phase current, and the output unit 216d outputs the gate voltage to the three-phase inverter 210. As a result, a zero-phase voltage of the same value is added to the voltage of each phase of the output of the three-phase inverter 210, and this zero-phase voltage causes a zero-phase current to flow.

[0088] Next, a zero-phase current is passed (step S05a). Specifically, first, the three-phase inverter 210 outputs the gate voltage of each IGBT 5 derived by the calculation unit 216c for a predetermined time (magnetization time). The predetermined time is the time required for the magnetization state of the variable magnetic force magnet 113 to change.

[0089] Next, the calculation unit 216c determines whether or not operation has been stopped (step S06). That is, it determines whether or not information to the effect that operation of the rotating electric machine 100 is to be stopped has been received. If it has not been determined that operation has been stopped (step S06 NO), steps S02 to S06 are repeated. If it has been determined that operation has been stopped (step S06 YES), the control ends. Note that while the same figure has described an example of an operation in which only a zero-phase current is applied to change the magnetic state of the variable magnetic force magnet, the ability to change the magnetic state can be further improved by simultaneously applying a zero-phase current and an armature current.

[0090] 12 is a graph conceptually illustrating phase voltage waveforms in which a three-phase AC voltage and a zero-phase component are superimposed in the control method for the rotating electrical machine system 20a according to the second embodiment. The voltage of each phase has a waveform in which an AC component and a zero-phase component are superimposed.

[0091] FIG. 13 is a first conceptual graph illustrating the maximum value of the required voltage in the control method for the rotary electric machine according to the second embodiment.

[0092] 13 shows a phase voltage Va1 generated by the first three-phase inverter 221 and a phase voltage Va2 generated by the second three-phase inverter 222. The difference between the zero-phase component (neutral point voltage) of the phase voltage Va1 and the zero-phase component (neutral point voltage) of the phase voltage Va2 is the voltage applied across the field winding 114. In the case shown in FIG. 13, the absolute value of the neutral point voltage is greater for the phase voltage Va1.

[0093] FIG. 14 is a second conceptual graph illustrating the maximum value of the required voltage in the control method for a rotary electric machine according to the second embodiment.

[0094] 14 similarly shows a phase voltage Vb1 generated by the first three-phase inverter 221 and a phase voltage Vb2 generated by the second three-phase inverter 222. As shown in FIG.

[0095] In the case shown in FIG. 14, the absolute value of the neutral point voltage is equal between the phase voltage Vb1 and the phase voltage Vb2.

[0096] Comparing the case shown in Figure 13, in which the absolute value of the neutral point voltage is larger for phase voltage Va1, with the case shown in Figure 14, in which the absolute value of the neutral point voltage is equal for phase voltage Vb1 and phase voltage Vb2, the absolute value Vmaxb of the maximum voltage of the phase voltage in the case shown in Figure 14 is smaller than the absolute value Vmaxa of the maximum voltage of the phase voltage in the case shown in Figure 13.

[0097] In this way, the absolute value of the maximum voltage of the phase voltages can be minimized by equalizing the absolute value of the neutral point voltage of the phase voltages generated by the first three-phase inverter 221 and the absolute value of the neutral point voltage of the phase voltages generated by the second three-phase inverter 222. In other words, by equally sharing the zero-phase voltage between the two inverters, the maximum value of the required voltage during the magnetizing operation can be reduced and suppressed.

[0098] In the configuration of this embodiment, when performing a magnetization operation, the inverter must output a voltage waveform in which a three-phase AC voltage resulting from the magnetic flux of the magnet and a DC zero-phase voltage for energizing the field winding are superimposed. In a rotating electric machine drive circuit that does not have a boost circuit, behavior is limited by the DC voltage input to the inverter, and unless the peak value of the above-mentioned voltage waveform falls within the phase voltage output limit (-Vdc / 2 to +Vdc / 2), the magnetization operation cannot be performed due to insufficient voltage. By equally sharing the zero-phase voltage between the two inverters while maintaining the difference between them, the peak values ​​of each phase voltage become equal and are less likely to be subject to voltage limits. This reduces and suppresses the peak value of the voltage required for the magnetization operation.

[0099] 15 is a graph showing a magnetization operation pattern in the control method for a rotating electric machine according to the second embodiment. With respect to the magnetization operation during load operation, the field current, armature current, and armature voltage values ​​during and after magnetization are conceptually shown.

[0100] Regarding the field current, a field current of value if is passed through the field winding 114 during magnetization, and becomes zero after magnetization.

[0101] The armature current flows as zero-phase currents iz1 (= +if / √3) and iz2 (= -if / √3), which correspond to the field current, and becomes zero after magnetization. Furthermore, during magnetization, the absolute value of the negative side of the d-axis current (id1 = id2), which is the current element that generates magnetic flux, becomes larger than after magnetization. Accordingly, during magnetization, the value of the q-axis current (iq1 = iq2), which acts as a torque current, decreases compared to after magnetization. As a result, the armature voltage required for the magnetization operation is reduced.

[0102] Regarding the armature voltage, during magnetization, the voltage is applied so that the absolute values ​​of one zero-phase sequence voltage (Vz1 = +|Vz|) and the other zero-phase sequence voltage (Vz2 = -|Vz|) are equal, and after magnetization, they become zero.

[0103] Below we will compare the magnetization operations and results for each of Cases 1 to 3. The details of each case are as follows:

[0104] (1) In all cases, a positive field current is applied during magnetization, and after magnetization, the same d-axis current and q-axis current are applied in all cases.

[0105] (2) In the first case, the same d-axis and q-axis currents as those after magnetization are applied during magnetization.

[0106] (3) In the second case, during magnetization, the d-axis current is kept the same as after magnetization, and a q-axis current adjusted to make the torque equivalent to that after magnetization is applied.

[0107] (4) In the third case, during magnetization, a negative d-axis current that is larger than that after magnetization and a q-axis current adjusted so that the torque matches that after magnetization are applied.

[0108] The simulation results for each case are shown below in the graphs shown in Figures 16 to 23. The horizontal axis of each graph represents the electrical angle (degrees), and the vertical axis represents the relative value (%) to the standard value.

[0109] Fig. 16 is a graph showing the state of each current based on a rotating coordinate system during magnetization in the first case, and Fig. 17 is a graph showing the state of each current based on a stationary coordinate system during magnetization in the first case.

[0110] Fig. 18 is a graph showing the state of each current based on a rotating coordinate system after magnetization in the first case, and Fig. 19 is a graph showing the state of each current based on a stationary coordinate system after magnetization in the first case.

[0111] In the first case, as described above, the same d-axis current and q-axis current are passed during magnetization as after magnetization.

[0112] Fig. 20 is a graph showing the state of each current based on a rotating coordinate system during magnetization in the second case. Fig. 21 is a graph showing the state of each current based on a stationary coordinate system during magnetization in the second case. The state after magnetization is as shown in Figs. 18 and 19.

[0113] In the second case, as described above, during magnetization, the d-axis current is the same as that after magnetization, and a q-axis current adjusted to make the torque equivalent to that after magnetization is passed.

[0114] Fig. 22 is a graph showing the state of each current based on a rotating coordinate system during magnetization in the third case. Fig. 23 is a graph showing the state of each current based on a stationary coordinate system during magnetization in the third case. The state after magnetization is as shown in Figs. 18 and 19.

[0115] In the third case, as described above, during magnetization, a negative d-axis current that is larger than that after magnetization and a q-axis current that is adjusted so that the torque matches that after magnetization are applied.

[0116] Figure 24 is Table 1, which shows the results of each case in which magnetization was performed under conditions of low-speed, light-load operation. Each value is the result of a simulation using an ideal current source with a rotation speed of 1,000 rpm, which is the low-speed range. Each value is a relative value (pu) to the standard value. Each column is the case number. Each row shows the d-axis current id, q-axis current iq, zero-phase current iz1, d-axis magnetic flux, torque, and total voltage to be borne by the armature winding during and after magnetization at low speed.

[0117] Here, the total voltage is the sum of the absolute value of the DC component of the phase voltage required for operation and the fundamental amplitude of the AC component. Note that the total voltage of the first three-phase inverter 221 and the second three-phase inverter 222 is equal to each other in order to equally share the zero-phase voltage (Vz (Vz1, Vz2)).

[0118] The reference values ​​for the d-axis current id, q-axis current iq, and zero-phase current iz are the current limit values. The reference value for the total voltage is the voltage limit value. The reference value for the torque is the maximum torque in the low-speed range. The d-axis magnetic flux is the no-load d-axis magnetic flux value in a demagnetized state so that it is minimum.

[0119] As shown in Table 1, the total voltage value during magnetization is below the specified value, being equal to or less than 1. In this way, under low-speed conditions, the influence of the AC component is small and the voltage required for the magnetization operation is below the limit, so the magnetization operation can be performed.

[0120] Figure 25 is a table showing the results of each case in which magnetization was performed under high-speed conditions. Each value is the result of a simulation using an ideal current source at a rotation speed of 9000 rpm, which is the high-speed range. The table structure and the definitions of each value are the same as those in Table 1.

[0121] As shown in Table 2, under high-speed conditions, the total voltage during magnetization is 2.09 in Case 1, 2.03 in Case 2, and 0.91 in Case 3. As shown, in Cases 1 and 2, the negative d-axis current does not sufficiently suppress the d-axis magnetic flux, so the voltage during magnetization under the current conditions shown in the table greatly exceeds the voltage limit, making it impossible to actually operate.

[0122] On the other hand, in the third case, the d-axis magnetic flux is suppressed to approximately zero by a negative d-axis current that is larger than the operating state after magnetization. As a result, the total voltage is below the voltage limit. In other words, in the third case, that is, in which a negative d-axis current that is larger than the one after magnetization and a q-axis current adjusted to match the torque after magnetization are applied during magnetization, the magnetization operation can be performed even under load operating conditions in the high-speed rotation range where voltage limits are strict.

[0123] The rotating electric machine 100 according to this embodiment is provided with two inverters (a first three-phase inverter 221 and a second three-phase inverter 222), but the capacity of each inverter is about half that of the three-phase inverter 210 in the first embodiment, so the size of the inverters in the rotating electric machine system 20a is not significantly larger than that of the rotating electric machine system 20 in the first embodiment. Furthermore, because the chopper circuit 32 is not required, the same effect can be obtained while the system is miniaturized.

[0124] In the second embodiment, two inverters are used, and the same number of conductors of the systems connected to each inverter are loaded into the slots, which provides various benefits regarding inverter harmonics.

[0125] Although the zero-phase sequence voltage of the inverter pulsates over time, the voltage applied to the field winding is the difference between the zero-phase sequence voltages of the two inverters, so if the output voltages of the two inverters are equal, the field current will not pulsate.

[0126] By controlling the phase of the carrier harmonics to be shifted between the two inverters, even if the current flowing through the conductors of each system pulsates, the total current within the slot, i.e., the pulsation of the magnetomotive force, is suppressed, thereby making it possible to suppress iron loss and eddy current loss in the magnet caused by carrier harmonics.

[0127] In a modification of the second embodiment, the first three-phase inverter 221 and the second three-phase inverter 222 are each a three-phase inverter equipped with current sensors for two phases. Although not shown in the figure, a current sensor 114f is provided between the first neutral point 127n and the second neutral point 128n to directly detect the field current. In other words, the current sensor 114f is provided on at least one of the lead wire from the first neutral point 127n and the lead wire from the second neutral point 128n.

[0128] Normally, when driving a three-phase AC rotating electric machine in which no zero-phase current flows, the sum of the three-phase currents is zero, so the current of the remaining phase can be estimated from the detected current values ​​of two phases.

[0129] Typically, in a three-phase AC rotating electric machine in which a zero-phase current flows, a three-phase inverter equipped with current sensors for all three phases is used because the sum of the three-phase currents is not zero. In contrast, in this embodiment, the detected value of the field current is used, and if the first inverter is equipped with current sensors (221u, 221v) for the U and V phases, the W-phase current of the first inverter can be detected using the following equation (2) based on the following relational equation (1). Iu1+Iv1+Iw1=If (1) Iw1=If-Iu1-Iv1 (2)

[0130] Similarly, if the second inverter also has U-phase and V-phase current sensors (222u, 222v), the W-phase current of the second inverter can be detected using the following equation (4) based on the following relational equation (3). Iu2+Iv2+Iw2=If (3) Iw2=If-Iu2-Iv2 (4)

[0131] According to this embodiment, since three-phase inverters equipped with current sensors for two phases are widely used, it is possible to configure a drive circuit by combining only general inverters.

[0132] [Third embodiment]

[0133] FIG. 26 is a circuit diagram showing the configuration of a rotating electrical machine system according to the third embodiment.

[0134] The rotating electric machine system 20 includes a rotating electric machine 100 and a rotating electric machine drive circuit 200 for the rotating electric machine 100 .

[0135] First, the rotating electric machine drive circuit 200 uses an external DC power supply 1 as a power source to supply AC power to the armature winding 125 of the rotating electric machine 100, and also supplies DC power to the field winding 114 of the rotating electric machine 100. Here, the DC power supply 1 is a power supply having a first power supply 1a and a second power supply 1b, and having a midpoint 2 that is a connection point between the first power supply 1a and the second power supply 1b. The first power supply 1a and the second power supply 1b have the same voltage value, but may have different voltage values. A midpoint lead 2m is provided from the midpoint 2 for connection.

[0136] The rotating electric machine drive circuit 200 includes a three-phase inverter 210 and a controller 215 .

[0137] First, as described above, the stator 120 has the armature winding 125. The armature winding 125 has phase conductors connected in parallel to one another, namely, a U-phase conductor 126u, a V-phase conductor 126v, and a W-phase conductor 126w. One end of the U-phase conductor 126u, the V-phase conductor 126v, and the W-phase conductor 126w is connected to external connection terminals 131a, 131b, and 131c, respectively. The other end of the U-phase conductor 126u, the V-phase conductor 126v, and the W-phase conductor 126w is connected to one another at a neutral point 126n. A neutral point lead wire 126m is provided from the neutral point 126n for connection.

[0138] On the other hand, when changing the magnetic force of the variable magnetic force magnet 113 in a state including the normal operating state of the rotating electric machine 100, the voltage of the AC power supplied to each phase of the armature winding 125 is shifted by the same voltage value in the same direction (positive or negative). That is, a predetermined voltage of the same sign and absolute value is superimposed on the time-averaged zero AC power voltage for each phase. In this way, the neutral point 126n is shifted to the predetermined zero-phase sequence voltage. As a result, a potential difference is generated on both sides of the field winding 114, and a predetermined zero-phase sequence current flows through the field winding 114.

[0139] Next, a circuit configuration for passing a field current through the field winding 114 provided on the rotor 110 will be described. A first end 114a of the field winding 114 is electrically connected or configured to be electrically connectable to a neutral point 126n of the armature winding 125 via a first slip ring 117a. A second end 114b of the field winding 114 is electrically connected or configured to be electrically connectable to a midpoint connection line 114m connected to an external connection terminal 132 via a second slip ring 117b. The external connection terminal 132 is connected or configured to be electrically connectable to a midpoint lead line 2m from the midpoint 2 of the DC power supply 1.

[0140] In addition, the stationary side (neutral point lead wire 126m and neutral point connection wire 114m) that mechanically contacts the first slip ring 117a and the second slip ring 117b to electrically connect them respectively has brushes, for example, that contact each slip ring, but these are not shown in the figure.

[0141] The zero-phase current can be adjusted using only the first three-phase inverter 221, and the current flowing through the field winding 114, that is, the magnetic force applied to the variable magnetic force magnets 113, 113a can be adjusted.

[0142] This embodiment and the second embodiment are similar in that they both utilize the zero-phase sequence component for the field current, but they differ in the magnitude of the available zero-phase sequence voltage. In this embodiment, the voltage of the DC voltage source is maximized by dividing it in half, while in the second embodiment, the voltage of the DC voltage source is maximized. That is, in the second embodiment, the voltage utilization rate of the zero-phase sequence component is doubled, allowing for more active utilization of the zero-phase sequence current.

[0143] According to the embodiments described above, it is possible to provide a rotating electric machine drive circuit, a rotating electric machine system, and a method for controlling a rotating electric machine that are capable of reducing the voltage required for magnetization operation in a memory motor having a field winding in its rotor.

[0144] [Other embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0145] 1...DC power supply, 1a...first power supply, 1b...second power supply, 2...neutral point, 2m...neutral point lead wire, 5...insulated gate bipolar transistor (IGBT), 6...three-phase inverter, 10...rotating electric machine, 11...armature winding, 20...rotating electric machine system, 30...rotating electric machine system as a comparative example, 31...field winding, 32...chopper circuit, 100, 100a...rotating electric machine, 100p...magnetic pole, 110, 110a...rotor, 111...rotor shaft, 112...rotor core, 112a...inner magnet housing outer flux barrier, 112b...inner magnet housing, 112c...inner magnet housing inner flux barrier of the outer magnet housing, 112d...inner bridge, 112e...outer flux barrier of the outer magnet housing, 112f...outer magnet housing, 112g...inner flux barrier of the outer magnet housing, 112h...outer bridge, 112j...outer central flux barrier, 112s...rotor core surface, 113, 113a...variable magnetic force magnet, 114, 114s...field winding, 114a...first end, 114b...second end, 114m...midpoint connecting wire, 115...inner fixed magnetic force magnet, 116...outer fixed magnetic force magnet, 117a...first slip ring, 117b...second slip ring, 118 , 118a... magnetized portion, 120... stator, 121... stator core, 121x... inner peripheral surface of stator core, 122... teeth portion, 122a... slot portion, 123... yoke portion, 125... armature winding, 125n... neutral point, 126... armature winding conductor, 126m... neutral point lead wire, 126n... neutral point, 126u... U-phase conductor, 126v... V-phase conductor, 126w... W-phase conductor, 127... armature winding first series conductor, 127m... neutral point lead wire, 127n... neutral point, 127u... first series U-phase conductor, 127v... first series V-phase conductor, 127w... first series W-phase conductor, 128... armature winding second series conductor, 128m...neutral point lead wire, 128n...neutral point, 128u...second series U-phase conductor, 128v...second series V-phase conductor, 128w...second series W-phase conductor, 130, 131a, 131b, 131c, 132, 133a, 133b, 133c, 134a, 134b, 134c...external connection terminals, 200, 200a...rotating electric machine drive circuit, 210...three-phase inverter, 215...controller, 215a...input unit, 215b...storage unit, 215c...calculation unit, 215d...output unit, 216...controller, 216a...input unit, 216b...storage unit, 216c...calculation unit, 216d...output unit,221...first three-phase inverter, 222...second three-phase inverter, MF1, MF2...magnetic field, CL...rotation center axis,

Claims

1. It comprises a three-phase inverter that converts DC power to three-phase AC power, and a controller that controls the three-phase inverter, The zero-phase current generated by the potential difference between the midpoint, which has a potential midway between the ends of the DC power supply that supplies the DC power, and the three-phase inverter, is used to generate the field current. When the direction in phase with the no-load induced voltage is defined as the q-axis, and the direction with a phase lag of 90 degrees electrical angle relative to the q-axis is defined as the d-axis, the field current generated by the three-phase inverter by the controller includes a d-axis current in the negative direction with respect to the d-axis. A rotating electric motor drive circuit characterized by the following.

2. A rotating electric machine having a stator core, a three-phase armature winding wound around the stator core, a rotor core, a variable force magnet housed within the rotor core, and a field winding positioned near the variable force magnet that changes the magnetization state of the variable force magnet by the flow of a zero-phase current. The rotating electric motor drive circuit according to claim 1, A rotating electric machine system characterized by having the following features.

3. A rotating electric machine having a stator core, a three-phase armature winding wound around the stator core, a rotor core, a variable force magnet provided on the rotor core, and a field winding, A three-phase inverter that converts DC power into three-phase AC power and supplies the three-phase AC power to the three-phase armature winding, The system includes a controller that controls the three-phase inverter, One end of the field winding is provided so as to be electrically connectable to a midpoint having a potential midway between the ends of the DC power supply that supplies the DC power. The other end of the field winding is provided so as to be electrically connectable to the neutral point of the three-phase armature winding. The zero-phase current generated by the potential difference between the three-phase inverter and the aforementioned inverter is used as the field current. As the reference phase of the three-phase AC current of the three-phase AC power, the direction in phase with the no-load induced voltage generated in the three-phase armature winding when the three-phase AC current is not flowing during forward rotation is defined as the q-axis, and the direction of phase lagging 90 degrees electrical angle with respect to the q-axis is defined as the d-axis. The direction in which the no-load induced voltage increases when the field current flowing through the field winding is energized is defined as positive. When the aforementioned field current is applied in the positive direction, A rotating electric machine system characterized in that the three-phase alternating current supplied from the three-phase inverter to the three-phase armature winding includes a negative d-axis current.

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