阅读说明：本技术 励磁绕组型旋转电机 (Field winding type rotating electrical machine ) 是由 濑口正弘 于 2019-09-02 设计创作，主要内容包括：励磁绕组型的旋转电机(30)包括：励磁绕组(70、73),其具有第一绕组部(71a、74a)和第二绕组部(71b、74b)的串联连接体；以及转子(60),其具有沿径向突出的主极部(62),第一绕组部和第二绕组部分别卷绕于各主极部,用于使励磁绕组感应出励磁电流的谐波电流流过定子绕组(31U～31W)。旋转电机包括连接到上述串联连接体的两端的二极管(80、81)以及与第二绕组部并联连接的电容器(90)。构成有包括第一绕组部和电容器的串联共振电路、以及包括第二绕组部和电容器的并联共振电路,在将第一绕组部的电感设为L1,将第二绕组部的电感设为L2的情况下,第一绕组部和第二绕组部的电感设定成满足“0.5＜L2/L1＜2”和“0.5＜L1/L2＜2”中的至少一个。(A field winding type rotating electrical machine (30) is provided with: excitation windings (70, 73) having a series connection body of first winding parts (71a, 74a) and second winding parts (71b, 74 b); and a rotor (60) having main pole portions (62) protruding in the radial direction, the first winding portion and the second winding portion being wound around each of the main pole portions, respectively, for causing a harmonic current induced by an excitation current in the excitation winding to flow through the stator windings (31U-31W). The rotating electric machine includes diodes (80, 81) connected to both ends of the series-connected body, and a capacitor (90) connected in parallel to the second winding portion. A series resonance circuit including a first winding unit and a capacitor, and a parallel resonance circuit including a second winding unit and a capacitor are configured, and when the inductance of the first winding unit is L1 and the inductance of the second winding unit is L2, the inductances of the first and second winding units are set so as to satisfy at least one of "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2".)

1. A field winding type rotating electrical machine (30) comprising:

a stator (50) having stator windings (31U-31W);

an excitation winding (70, 73) having a series connection body of a first winding part (71a, 74a) and a second winding part (71b, 74 b); and

a rotor (60) having a rotor core (61) and main pole portions (62) that are provided at regular intervals in a circumferential direction and that protrude from the rotor core in a radial direction,

the first winding portion and the second winding portion are wound around the respective main pole portions, respectively, for causing a harmonic current of an excitation current induced in the excitation winding to flow through the stator winding,

the field winding type rotating electrical machine includes:

a diode (80, 81) having a cathode connected to the first winding section side of the two ends of the series connection body and an anode connected to the second winding section side of the two ends of the series connection body; and

a capacitor (90) connected in parallel with the second winding portion,

a series resonance circuit including the first winding portion and the capacitor and a parallel resonance circuit including the second winding portion and the capacitor are configured,

when the inductance of the first winding part is L1 and the inductance of the second winding part is L2, the inductance of each of the first winding part and the second winding part is set to satisfy at least one of "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2".

2. The field winding type rotary electric machine according to claim 1,

the inductance of each of the first winding portion and the second winding portion is set to satisfy both "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2".

3. A field winding type rotating electrical machine (30) comprising:

a stator (50) having stator windings (31U-31W);

an excitation winding (70, 73) having a series connection body of a first winding part (71a, 74a) and a second winding part (71b, 74 b); and

a rotor (60) having a rotor core (61) and main pole portions (62) that are provided at regular intervals in a circumferential direction and that protrude from the rotor core in a radial direction,

the first winding portion and the second winding portion are wound around the respective main pole portions, respectively, for causing a harmonic current of an excitation current induced in the excitation winding to flow through the stator winding,

the field winding type rotating electrical machine includes:

a diode (80, 81) having a cathode connected to the first winding section side of the two ends of the series connection body and an anode connected to the second winding section side of the two ends of the series connection body; and

a capacitor (90) connected in parallel with the second winding portion,

a series resonance circuit including the first winding portion and the capacitor and a parallel resonance circuit including the second winding portion and the capacitor are configured,

the series resonant circuit and the parallel resonant circuit have the same resonance frequency, the torque of the rotating electrical machine is maximized when the frequency of the harmonic current is made to coincide with the resonance frequency, the frequency of the harmonic current when the torque of the rotating electrical machine is maximized is set to a reference frequency f0,

of the two frequencies of the harmonic current at which the torque of the rotating electrical machine is equal to the allowable lower limit value (Tmin), the lower limit frequency fL and the higher upper limit frequency fH are expressed by the following expression c1,

[ mathematical formula 1 ]

The inductance of each of the first and second winding portions is set to satisfy at least one of the following expressions c2 and c3 when the inductance of the first winding portion is L1 and the inductance of the second winding portion is L2,

[ mathematical formula 2 ]

[ mathematical formula 3 ]

4. The field winding type rotary electric machine according to any one of claims 1 to 3,

when the amount of phase shift between the current flowing through the series resonant circuit and the current flowing through the parallel resonant circuit is θ s, "120 ° < θ s < 240 °".

5. The field winding type rotary electric machine according to any one of claims 1 to 4,

the first winding portion is disposed radially closer to the stator than the second winding portion,

when the number of turns of the first winding portion is N1 and the number of turns of the second winding portion is N2, "N1 < N2".

6. The field winding type rotary electric machine according to any one of claims 1 to 5,

the diodes are a rectifier diode (80) and a zener diode (81) connected in parallel with each other.

7. The field winding type rotary electric machine according to any one of claims 1 to 5,

the diode is constituted only by a zener diode (81).

8. The field winding type rotary electric machine according to any one of claims 1 to 7,

the diode is a plurality of zener diodes (81) connected in series.

9. The field winding type rotary electric machine according to any one of claims 1 to 8,

the frequency of the harmonic current is set to a resonance frequency of the series resonant circuit.

Technical Field

The present disclosure relates to a field winding type rotating electrical machine.

Background

As such a rotating electrical machine, as shown in patent document 1, there is known a rotating electrical machine including: a stator having a stator winding; an excitation winding formed of a series connection body of a first winding part and a second winding part; a rotor having a rotor core and a main pole portion; and a diode. The main pole portions are provided at predetermined intervals in the circumferential direction and protrude from the rotor core in the radial direction. In the rotor, a cathode of a diode is connected to the first winding unit side and an anode of the diode is connected to the second winding unit side at both ends of the series-connected unit. The first winding portion and the second winding portion are wound around the respective main pole portions. A fundamental current mainly for generating torque and a harmonic current mainly for exciting the field winding flow through the stator winding.

When a harmonic current flows, a main magnetic flux flows through a magnetic path including the circumferentially adjacent main pole and the rotor core. Since the main magnetic flux flows, induced voltages are generated in the first winding portion and the second winding portion connected in series, respectively, and currents are induced in the first winding portion and the second winding portion. At this time, the current flowing through the first winding portion and the second winding portion is rectified in one direction by the diode. Thereby, the excitation current flows through the field winding in the direction rectified by the diode, and the field winding is excited.

On the other hand, when a harmonic current flows, a leakage magnetic flux is generated in addition to the main magnetic flux. The leakage magnetic flux flows in a transverse manner from one of the circumferentially adjacent main pole portions to the other, and is interlinked with the field winding without passing through the rotor core. In this case, induced voltages having opposite polarities are generated in each winding portion, and the induced current is reduced. As a result, the total value of the currents induced in the first winding portion and the second winding portion decreases, and the excitation current flowing through the excitation winding decreases.

Therefore, the rotating electric machine described in patent document 1 includes a capacitor connected in parallel to the second winding portion. This increases the excitation current.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-42401

Disclosure of Invention

Here, in order to increase the torque of the rotating electric machine, it is desirable to further increase the field current.

A primary object of the present disclosure is to provide a field winding type rotating electrical machine capable of increasing a field current flowing through a field winding.

The present disclosure is a field winding type rotating electrical machine including: a stator having a stator winding;

a field winding having a series connection body of a first winding part and a second winding part; and

a rotor having a rotor core and main pole portions provided at predetermined intervals in a circumferential direction and protruding in a radial direction from the rotor core,

the first winding portion and the second winding portion are wound around the respective main pole portions, and are configured to allow a harmonic current, which is an excitation current induced in the excitation winding, to flow through the stator winding, and the motor includes:

a diode having a cathode connected to the first winding unit side of the two ends of the series-connected unit and an anode connected to the second winding unit side of the two ends of the series-connected unit; and

a capacitor connected in parallel with the second winding portion,

a series resonant circuit including the first winding unit and the capacitor, and a parallel resonant circuit including the second winding unit and the capacitor,

when the inductance of the first winding part is L1 and the inductance of the second winding part is L2, the inductances of the first winding part and the second winding part are set so as to satisfy at least one of "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2".

There is a rotating electrical machine having the following characteristics: when the resonance frequencies of the series resonance circuit and the parallel resonance circuit are equal to each other and the frequency of the harmonic current flowing through the stator winding is made to coincide with the resonance frequency, the excitation current is maximized and the torque is maximized. Here, the frequency of the harmonic current when the torque of the rotating electric machine is maximum is set as the reference frequency f 0.

Although it is desirable to set the frequency of the harmonic current at which the torque of the rotating electric machine becomes maximum, actually, the frequency range of the harmonic current is set to a certain width. In this case, the frequency range is set so that the torque of the rotating electric machine becomes equal to or more than the lower limit value of the required torque.

Here, of the two frequencies of the harmonic current at which the torque matches the allowable lower limit value Tmin, the lower one is set as the lower limit frequency fL, and the higher one is set as the upper limit frequency fH. In the rotary electric machine which the inventors of the present application are developing, the lower limit frequency fL is a frequency 0.7 times the reference frequency f0 and the upper limit frequency fH is a frequency 1.4 times the reference frequency f 0. On the premise of the above-described relationship between the lower limit frequency fL and the upper limit frequency fH with the reference frequency f0, the inventors of the present application have obtained the following findings: if a condition is set such that the resonance frequency of the series resonant circuit matches the reference frequency f0, a condition "0.5 < L2/L1 < 2" is derived. Further, the inventors of the present application have obtained the following findings: if a condition is set such that the resonance frequency of the parallel resonance circuit matches the reference frequency f0, a condition "0.5 < L1/L2 < 2" is derived.

Therefore, in the present disclosure, the inductance of each of the first winding portion and the second winding portion is set to satisfy at least one of "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2". This can increase the excitation current.

Drawings

The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. The drawings are as follows.

Fig. 1 is an overall configuration diagram of a control system of a rotating electric machine according to a first embodiment.

Fig. 2 is a diagram showing an electric circuit included in the rotor.

Fig. 3 is a cross-sectional view of the rotor and stator.

Fig. 4 is a diagram showing transition of a fundamental current, a harmonic current, and the like.

Fig. 5 is a diagram showing transition of three-phase currents.

Fig. 6 is a diagram showing transition of a fundamental current, a harmonic current, and the like.

Fig. 7 is a diagram showing transition of three-phase currents.

Fig. 8 is a diagram showing a pattern of generation of induced voltage.

Fig. 9 is a diagram showing a circuit corresponding to modes 2 and 3.

Fig. 10 is a diagram showing a series resonance circuit.

Fig. 11 is a diagram showing a parallel resonance circuit.

Fig. 12 is a diagram showing a rectifier circuit for the excitation current.

Fig. 13 is a timing chart showing changes in currents flowing through the first winding portion, the second winding portion, and the capacitor.

Fig. 14 is a timing chart showing changes in currents flowing through the first winding portion, the second winding portion, and the capacitor.

Fig. 15 is a timing chart showing results of an actual simulation of currents flowing through the first winding unit, the second winding unit, and the capacitor.

Fig. 16 is a characteristic diagram showing a relationship among the frequency of the harmonic current, the excitation current, and the torque.

Fig. 17 is a diagram showing an electric circuit included in the rotor according to modification 2 of the first embodiment.

Fig. 18 is a diagram showing an electric circuit included in the rotor according to modification 3 of the first embodiment.

Fig. 19 is a diagram showing an electric circuit included in the rotor according to modification 3 of the first embodiment.

Fig. 20 is a cross-sectional view of a rotor and a stator according to modification 4 of the first embodiment.

Fig. 21 is a diagram showing the flow of magnetic flux in the second embodiment.

Fig. 22 is a diagram showing the flow of magnetic flux.

Fig. 23 is a cross-sectional view of a rotor and a stator of the third embodiment.

Fig. 24 is an enlarged view of a part of fig. 23.

Fig. 25 is a cross-sectional view of a rotor and a stator of the fourth embodiment.

Fig. 26 is a diagram showing an electric circuit included in the rotor.

Fig. 27 is a diagram showing an electric circuit included in the rotor according to the modification of the fourth embodiment.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings. The rotating electric machine according to the present embodiment is mounted on a vehicle, for example. In the following embodiments, the same or equivalent portions are denoted by the same reference numerals in the drawings, and the description thereof will be referred to for the portions having the same reference numerals.

< first embodiment >

First, description will be given with reference to fig. 1 to 3. The control system includes a dc power supply 10, an inverter 20, a rotating electric machine 30, and a control device 40. In the present embodiment, a field winding type synchronous rotating electrical machine is used as the rotating electrical machine 30. In the present embodiment, the control device 40 controls the rotating electrical machine 30 such that the rotating electrical machine 30 functions as an Integrated Starter Generator (ISG) or a Motor Generator (MG), which is a Motor Generator. For example, the present invention is configured as an electromechanical integrated drive device including the rotating electrical machine 30, the inverter 20, and the control device 40, or the rotating electrical machine 30, the inverter 20, and the control device 40 are each configured by a separate component.

The rotary electric machine 30 includes a rotor 60 having a field winding 70. The field winding 70 is formed of a series connection body of a first winding portion 71a and a second winding portion 71 b. The field winding 70 is formed by compression molding, for example. This improves the space factor and improves the ease of assembly of the field winding. The field winding 70 may be made of, for example, an aluminum wire. The aluminum wire has a small specific gravity, so that the centrifugal force when the rotor 60 rotates can be reduced. In addition, aluminum wire has lower strength and hardness than copper wire, and is suitable for compression molding.

The rotary electric machine 30 includes a stator 50 having stator windings 31. The stator winding 31 is made of, for example, copper wire, and includes a U-phase winding 31U, V-phase winding 31V, W-phase winding 31W arranged in a state shifted from each other by 120 ° in electrical angle.

Inverter 20 includes a series connection of U-phase upper arm switch SUp, V-phase upper arm switch SVp, W-phase upper arm switch Swp, and U-phase lower arm switch SUn, V-phase lower arm switch SVn, and W-phase lower arm switch SWn. The first end of the U-phase winding 31U, V phase winding 31V, W phase winding 31W is connected to the connection point of the U-phase upper arm switch SUp, the V-phase upper arm switch SVp, the W-phase upper arm switch SWp, and the U-phase lower arm switch SUn, the V-phase lower arm switch SVn, and the W-phase lower arm switch SWn. The second ends of the U-phase winding 31U, V phase winding 31V, W phase winding 31W are connected at a neutral point. That is, in the present embodiment, the U-phase winding 31U, V phase winding 31V, W phase winding 31W is star-connected. In the present embodiment, the switches SUp to SWn are IGBTs. A freewheeling diode is connected in anti-parallel to each of the switches SUp, SVp, SWp, SUn, SVn, and SWn.

The collectors of the U-phase upper arm switch SUp, the V-phase upper arm switch SVp, and the W-phase upper arm switch SWp are connected to the positive terminal of the dc power supply 10. The emitters of the U-phase lower arm switch SUn, the V-phase lower arm switch SVn, and the W-phase lower arm switch SWn are connected to the negative terminal of the dc power supply 10. The smoothing capacitor 11 is connected in parallel with the dc power supply 10.

The control system includes an angle detection section 41. The angle detection unit 41 outputs an angle signal, which is a signal corresponding to the rotation angle of the rotor 60. An output signal of the angle detection unit 41 is input to the control device 40.

Next, the stator 50 and the rotor 60 will be explained.

The stator 50 and the rotor 60 are coaxially arranged together with the rotary shaft 32. In the following description, a direction in which the rotary shaft 32 extends is an axial direction, a direction in which the rotary shaft 32 radially extends from the center thereof is a radial direction, and a direction in which the rotary shaft 32 circumferentially extends around the center thereof is a circumferential direction.

The stator 50 is formed of a laminated steel plate made of a soft magnetic material, and the stator 50 includes an annular stator core 51 and a plurality of pole teeth 52 protruding radially inward from the stator core 51. In the present embodiment, the phase windings 31U, 31V, and 31W are wound in a distributed manner or in a concentrated manner around the teeth 52. As shown in fig. 3, in the present embodiment, forty-eight pole teeth are provided at equal intervals in the circumferential direction. Therefore, the rotary electric machine 30 is a forty-eight slot rotary electric machine.

The rotor 60 is formed of a laminated steel plate made of a soft magnetic material, and the rotor 60 includes a cylindrical rotor core 61 and a plurality of main pole portions 62 protruding radially outward from the rotor core 61. The surface of the leading end side of each main pole portion 62 faces the end surface of the tooth 52. In the present embodiment, eight main poles 62 are provided at equal intervals in the circumferential direction.

In each main pole portion 62, a first winding portion 71a is wound radially outward, and a second winding portion 71b is wound radially inward of the first winding portion 71 a. In each main pole portion 62, the winding directions of the first winding portion 71a and the second winding portion 71b are the same as each other. The winding direction of the respective winding portions 71a, 71b wound around one of the circumferentially adjacent main pole portions 62 is opposite to the winding direction of the respective winding portions 71a, 71b wound around the other. Therefore, the magnetization directions of the circumferentially adjacent main pole portions 62 are opposite to each other.

Fig. 2 shows a rotor-side circuit including the respective winding portions 71a and 71b wound around the common main pole portion 62. The rotor 60 is provided with a diode 80 and a capacitor 90 as a rectifying element. A first end of the first winding portion 71a is connected to a cathode of the diode 80, and a first end of the second winding portion 71b is connected to a second end of the first winding portion 71 a. An anode of the diode 80 is connected to a second end of the second winding portion 71 b. The capacitor 90 is connected in parallel to the second winding portion 71 b. In fig. 2, L1 represents the inductance of the first winding portion 71a, L2 represents the inductance of the second winding portion 71b, and C represents the capacitance of the capacitor 90.

Next, the control device 40 will be explained. A part or all of the functions of the control device 40 may be configured by hardware such as one or a plurality of integrated circuits, for example. Each function of the control device 40 may be constituted by software stored in a non-transitory tangible storage medium and a computer that executes the software, for example.

The control device 40 acquires the angle signal of the angle detection unit 41, and generates a drive signal for turning on and off the switches SUp to SWn constituting the inverter 20 based on the acquired angle signal. Specifically, when the rotating electric machine 30 is driven as a motor, the control device 40 generates a drive signal for turning on and off the arm switches SUp to SWn and supplies the generated drive signal to the gates of the arm switches SUp to SWn in order to convert dc power output from the dc power supply 10 into ac power and supply the ac power to the U-phase winding 31U, V and the phase winding 31V, W and the phase winding 31W. On the other hand, when the rotating electrical machine 30 is driven as a generator, the control device 40 generates a drive signal for turning on and off the arm switches SUp to SWn in order to convert ac power output from the U-phase winding 31U, V phase winding 31V, W phase winding 31W into dc power and supply the dc power to the dc power supply 10.

The controller 40 turns on and off the switches SUp to SWn so that the combined current of the fundamental wave current and the harmonic current flows through the phase windings 31U, 31V, and 31W. As shown in fig. 4 (a), the fundamental wave current is a current mainly used for generating torque in the rotating electrical machine 30. As shown in fig. 4 (b), the harmonic current is a current mainly used for exciting the field winding 70. Fig. 4 (c) shows a phase current which is a combined current of a fundamental current and a harmonic current. The values on the vertical axis shown in fig. 4 represent the relative relationship between the magnitudes of the waveforms shown in fig. 4 (a) to 4 (c). As shown in fig. 5, phase currents IU, IV, and IW flowing through the phase windings 31U, 31V, and 31W are shifted by an electrical angle of 120 ° respectively.

In the present embodiment, as shown in fig. 4 (a) and (b), the envelope of the harmonic current has 1/2 cycles of the fundamental current. In fig. 4 (b), an envelope is indicated by a chain line. Further, the timing at which the envelope reaches its peak is shifted from the timing at which the fundamental current reaches its peak. Specifically, the timing at which the envelope reaches its peak is the timing at which the fluctuation center (0) of the fundamental current is present. The control device 40 independently controls the amplitude and the period of each of the fundamental wave current and the harmonic current.

By passing the harmonic current shown in fig. 4 (b), the maximum value of the phase currents flowing through the phase windings 31U, 31V, and 31W can be reduced, and the torque of the rotating electrical machine 30 can be set to the commanded torque without increasing the capacity of the inverter 20.

Incidentally, as the harmonic current, a current shown in (b) of fig. 6 may be used. Fig. 6 (a) and (c) correspond to fig. 4 (a) and (c) described above. As shown in fig. 6 (a) and (b), the timing at which the envelope of the harmonic current reaches its peak is the timing at which the fundamental current reaches its peak. The harmonic current shown in fig. 6 (b) is 1/4 in which the phase of the harmonic current shown in fig. 4 (b) is shifted by the period of the fundamental current. Fig. 7 shows the course of the phase currents IU, IV, IW flowing through the phase windings 31U, 31V, 31W in this case.

In the present embodiment, a series resonant circuit including the first winding portion 71a, the capacitor 90, and the diode 80 is configured, and a parallel resonant circuit including the second winding portion 71b and the capacitor 90 is configured. The first resonance frequency, which is the resonance frequency of the series resonance circuit, is f1, and the second resonance frequency, which is the resonance frequency of the parallel resonance circuit, is f 2. The resonance frequencies f1 and f2 are expressed by the following formulas (eq1) and (eq 2).

[ mathematical formula 1 ]

[ mathematical formula 2 ]

When harmonic currents flow through the respective phase windings 31U, 31V, 31W, a ripple due to harmonics of the main magnetic flux is generated in a magnetic circuit including the circumferentially adjacent main pole 62, rotor core 61, pole teeth 52, and stator core 51. By generating the ripple of the main magnetic flux, induced voltages are generated in the first winding portion 71a and the second winding portion 71b, respectively, and currents are induced in the first winding portion 71a and the second winding portion 71 b. At this time, as shown in modes 1 and 4 of fig. 8, when induced voltages having the same polarity are generated in the first and second winding portions 71a and 71b, the induced currents of the first and second winding portions 71a and 71b do not cancel each other, and therefore the induced currents increase. The current flowing through the first and second winding portions 71a and 71b is rectified into one direction by the diode 80. As a result, the field current flows through the field winding 70 in the direction rectified by the diode 80, and the field winding is excited. In fig. 8, e1 indicates an induced voltage generated in the first winding portion 71a, and e2 indicates an induced voltage generated in the second winding portion 71 b.

On the other hand, when a harmonic current flows, leakage magnetic flux is easily generated in addition to the fluctuation of the main magnetic flux. The leakage magnetic flux flows from one of the circumferentially adjacent main pole portions 62 to the other in a crossing manner without passing through the rotor core 61, and is interlinked with the field winding 70. At this time, leakage magnetic flux interlinking the respective winding portions 71a and 71b is also generated. When the leakage magnetic flux is interlinked with the field winding 70, an induced voltage in a certain direction may be generated in the first winding portion 71a, and an induced voltage in a different direction may be generated in the second winding portion 71 b. As a result, the total value of the currents induced in the first winding portion 71a and the second winding portion 71b is reduced, and the excitation current flowing through the excitation winding 70 is further reduced.

In the present embodiment, the capacitor 90 is connected in parallel to the second winding portion 71 b. Therefore, as shown in modes 2 and 3 of fig. 8, even when the induced voltages generated in the first and second winding portions 71a and 71b have opposite polarities, the induced currents flow through the capacitor 90, and therefore the induced currents flowing through the first and second winding portions 71a and 71b do not cancel each other. Therefore, as shown in fig. 9 (a), the current induced by the first winding portion 71a and the current induced by the second winding portion 71b flow to the anode side of the diode 80 via the capacitor 90, and as shown in fig. 9 (b), the current flows from the capacitor 90 to the anode side of the diode 80 via the second winding portion 71 b. As a result, the field current flowing through the field winding 70 can be increased.

In the present embodiment, the frequency fh of the harmonic current flowing through the stator winding 31 is set to the same frequency as or a frequency near the first resonance frequency f 1. Therefore, the currents induced in the first and second winding portions 71a and 71b can be further increased, and the excitation current can be further increased.

Here, the present inventors further examined the cases of modes 2 and 3. This will be explained below.

The circuit shown in fig. 2 is basically constituted by three circuits shown in fig. 10 to 12. Fig. 10 shows a series resonant circuit composed of the first winding portion 71a, the capacitor 90, and the diode 80, and fig. 11 shows a parallel resonant circuit composed of the second winding portion 71b and the capacitor 90. Fig. 12 shows a rectifier circuit of the excitation current constituted by the first and second winding portions 71a and 71b and the diode 80.

In the series resonant circuit shown in fig. 10, the impedance is minimum and the alternating current is maximum at the first resonant frequency f 1. In addition, a half-wave current flows through the series resonant circuit due to the presence of the diode 80.

In the parallel resonant circuit shown in fig. 11, the impedance is minimum and the alternating current is maximum at the second resonant frequency f 2.

When the frequency of the harmonic current flowing through the stator winding 31 is the first resonance frequency f1, a current fluctuating at the first resonance frequency f1 is supplied to the capacitor 90 in the series resonance circuit. The current supplied to the capacitor 90 becomes a half-wave current through the diode 80. Here, the current blocked by the diode 80 in the series resonant circuit returns to the cathode side of the diode 80 via the second winding portion 71b of the parallel resonant circuit. When the first resonance frequency f1 and the second resonance frequency f2 are equal or close to each other, the ac currents flowing through the series resonance circuit and the parallel resonance circuit are at or close to the maximum value, respectively.

In the circuit shown in fig. 12, the combined impedance of the first winding portion 71a and the first winding portion 71b becomes very large in the vicinity of the first resonance frequency f 1. Therefore, the current flowing through the circuit shown in fig. 12 is mainly the current of the alternating component flowing through the circuits shown in fig. 10 and 11. In the circuit shown in fig. 12, a current of a dc component rectified by a diode 80 flows.

Next, fig. 13 and 14 show changes in the current flowing through the circuits shown in fig. 10 to 12. In fig. 13 and 14, IC indicates a capacitor current as a current flowing through the capacitor 90, and IL1 indicates a current flowing through the first winding portion 71 a. IL2 represents a current flowing through the second winding portion 71b, and If represents a current of a dc component flowing through the circuit shown in fig. 12, that is, an excitation current. The values on the vertical axis shown in fig. 13 and 14 are used to show the relative relationship between the magnitudes of the waveforms.

As shown by the arrows in fig. 10, the capacitor current IC flows in the direction from the first winding portion 71a toward the capacitor 90, and is positive. As shown by the arrows in fig. 10, the current IL1 flowing through the first winding portion 71a is positive when flowing in a direction from the first end toward the second end of the first winding portion 71 a. As shown by the arrows in fig. 11, the current IL2 flowing through the second winding portion 71b is positive when flowing in a direction from the first end toward the second end of the second winding portion 71 b. As shown by the arrow in fig. 12, the case where the excitation current If flows in the direction from the anode to the cathode of the diode 80 is positive.

Fig. 13 shows a state immediately after the excitation winding 70 starts to be excited. In the first period T1 of fig. 13, the capacitor current IC is a positive value. That is, in the series resonant circuit of fig. 10, in the first period T1, a current flows from the first winding portion 71a to the capacitor 90. The magnitude of the flowing capacitor current IC is equal to the magnitude of the current IL1 flowing through the first winding portion 71 a. Here, the frequency fh of the harmonic current flowing through the stator winding 31 is set to the first resonance frequency f1, whereby the alternating current flowing through the series resonance circuit increases.

In a second period T2 temporally adjacent to the first period T1 of fig. 13, the capacitor current IC is a negative value. That is, in the second period T2, in the parallel resonance circuit of fig. 11, a current flows from the capacitor 90 to the second winding portion 71 b. The magnitude of the capacitor current IC flowing out is equal to the magnitude of the positive current IL2 flowing through the second winding portion 71 b.

By repeating the state of the first period T1 and the state of the second period T2, the excitation current If increases as shown in fig. 14. Fig. 15 shows the results of simulation using a structure corresponding to the real machine model.

In the present embodiment, as shown in fig. 14, the amount θ s of phase shift between the current IL1 flowing through the first winding portion 71a and the current IL2 flowing through the second winding portion 71b is 180 ° in electrical angle. This makes it possible to cancel the ripple part of the combined magnetic field of the magnetic fields generated by the first and second winding portions 71a and 71b, and to smooth the ripple part of the combined magnetic field to a constant magnetic field.

The phase shift amount θ s may be a value other than 180 ° in "120 ° < θ s < 240 °". If the shift amount θ s is in the range of 180 ° ± 60 °, the pulsation of the combined magnetic field of the magnetic field generated by the current flowing through the first winding portion 71a and the magnetic field generated by the current flowing through the second winding portion 71b can be reduced.

In order to set the phase shift amount θ s as described above, in the present embodiment, the inductance L1 of the first winding portion 71a and the inductance L2 of the second winding portion 71b are set so as to satisfy the following expressions (eq3) and (eq 4). This setting will be explained below.

[ mathematical formula 3 ]

[ mathematical formula 4 ]

Fig. 16 shows the relationship among the frequency fh of the harmonic current, the field current flowing through the field winding 70, and the torque of the rotary electric machine 30. In a range where the frequency fh as the harmonic current is expected to be used, the torque of the rotating electrical machine 30 becomes maximum at a certain frequency. The frequency at which the maximum torque is reached is referred to as a reference frequency f 0. The reference frequency f0 is a frequency when the first resonance frequency f1 and the second resonance frequency f2 are equal to each other. When the frequency fh of the harmonic current deviates from the reference frequency f0, the field current decreases, and the torque decreases. Here, the smaller the field current, the lower the torque.

Here, it is considered that the torque of the rotating electrical machine 30 is equal to or greater than the allowable lower limit Tmin. The allowable lower limit Tmin is set to a value of, for example, 80% to 90% of the maximum torque. In fig. 16, of the two frequencies fH of the harmonic current at which the torque matches the allowable lower limit value Tmin, the lower frequency is referred to as a lower limit frequency fL, and the higher frequency is referred to as an upper limit frequency fH. Here, the lower limit frequency fL and the upper limit frequency fH are expressed by the following expression (eq 5). For example, a is set to 0.3 (30%), and B is set to 0.4 (40%).

[ math figure 5 ]

In the above formula (eq5), the real numbers A and B are set to values in the range of "0 < A.ltoreq.0.5 and 0 < B.ltoreq.0.5", for example, and preferably in the range of "0 < A.ltoreq.0.4 and 0 < B.ltoreq.0.4". Preferably, the first resonance frequency f1 and the second resonance frequency f2 are in a frequency range higher than the lower limit frequency fL and lower than the upper limit frequency fH, respectively. From this, the following expressions (eq6) and (eq7) were derived.

[ mathematical formula 6 ]

(1-A)f0＜f1＜(1+B)f0…(eq6)

[ mathematical formula 7 ]

(1-A)f0＜f2<(1+B)f0…(eq7)

The following equation (eq8) is derived from the above equations (eq6) and (eq 1).

[ mathematical formula 8 ]

When the following formula (eq9) is used, the above formula (eq8) is the following formula (eq 10).

[ mathematical formula 9 ]

[ MATHEMATICAL FORMULATION 10 ]

In the above formula (eq10), when L1 is collated, the following formula (eq11) is derived.

[ mathematical formula 11 ]

On the other hand, the following formula (eq12) is derived from the above formulas (eq7) and (eq 2).

[ MATHEMATICAL FORMULATION 12 ]

The following formula (eq13) is derived from the above formula (eq12) and (eq9) in the same manner as the above formula (eq 11).

[ mathematical formula 13 ]

Here, the following equation (eq14) is derived from the condition that the first resonance frequency f1 is equal to the reference frequency f 0. In this case, "L1 ═ K".

[ CHEMICAL EQUATION 14 ]

The formula (eq3) is derived by substituting "K ═ L1" into the formula (eq13) and then rectifying the result.

On the other hand, the following equation (eq15) is derived from the condition that the second resonance frequency f2 is equal to the reference frequency f 0. In this case, L2 ═ K.

[ mathematical formula 15 ]

The formula (eq4) is derived by substituting "K ═ L2" into the formula (eq11) and then rectifying the result.

When "a is 0.3 and B is 0.4", the above formula (eq3) is "0.5 < L2/L1 < 2". When "a is 0.3 and" B is 0.4 ", the above formula (eq4) is" 0.5 < L1/L2 < 2 ".

Here, the relationship between L1 and L2 may be set to "L1 — L2", for example. In this case, f1 becomes f2, and the effect of increasing the excitation current becomes large.

For example, L1 and L2 may be set so that "L1 ≠ L2" under the conditions that "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2" are satisfied. A specific example of the setting will be described below.

< example 1>

If f 1> f2 is set, the expression "L2 > L1" is derived from the above expressions (eq1) and (eq 2). In this case, the following expression (eq16) holds.

[ mathematical formula 16 ]

Here, "a" is 0.2 and "B" is 0.2. This setting is, for example, a setting in which the allowable lower limit value Tmin is set to a value of 90% of the maximum torque. In this case, "1 < L2/L1 < 1.56" and "0.69 < L1/L2 < 1" are derived from the above formulae (eq3), (eq4), (eq 16).

< example 2 >

If f2 > f1 is set, the expression "L1 > L2" is derived from the above expressions (eq1) and (eq 2). In this case, the following expression (eq17) holds.

[ mathematical formula 17 ]

Here, as in the above-mentioned specific example 1, "a" is 0.2 and "B" is 0.2 ". In this case, "0.69 < L2/L1 < 1" and "1 < L1/L2 < 1.56" are derived from the above formulae (eq3), (eq4), (eq 17).

As described above, when the absolute value of A, B is made smaller, that is, the frequency range defined by fL to fH is made narrower, the ranges that L2/L1 and L1/L2 can take respectively become narrower.

As described above, by setting the inductance L1 of the first winding part 71a and the inductance L2 of the second winding part 71b so as to satisfy the above-described equations (eq3) and (eq4), the excitation current can be increased.

Further, according to the present embodiment, a configuration in which the excitation current is increased based on a simple parameter such as each of the inductances L1 and L2 can be realized.

< modification 1 of the first embodiment >

The first winding portion and the second winding portion of the field winding may be formed of flat wires, respectively. By using the flat wire, the space factor of the field winding can be increased, and the loss can be reduced. In addition, according to the flat wire, when a centrifugal force acts on the winding portion, the load applied between the windings can be received by the surface, and therefore, the coating of the winding can be prevented from being damaged. Further, according to the flat wire, the ampere-turn number (AT) can be increased, and the excitation range of the field winding can be expanded. As a result, torque controllability is improved.

The first winding portion and the second winding portion may be each formed of an α -winding using a flat wire. As the winding portion of the α -winding using the flat wire, for example, a structure shown in fig. 5 (a) of japanese patent application laid-open No. 2008-178211 can be used.

< modification 2 of the first embodiment >

As shown in fig. 17, a zener diode 81 may be connected in parallel to the rectifier diode 80. Therefore, surge voltage applied to the diode 80, the field winding 70, and the capacitor 90 can be absorbed, and deterioration of the diode 80, the field winding 70, and the capacitor 90 can be suppressed.

The surge voltage can be generated, for example, by largely distorting a harmonic current flowing through the stator winding 31 from a sine wave. In particular, as described in japanese patent laid-open nos. 2010-273476 and 2018-98907, when 180-degree rectangular wave conduction control is performed, if a pulse-like voltage is superimposed on a voltage applied to the stator winding 31 in order to flow a harmonic current, distortion of the harmonic current becomes large, and the surge voltage tends to become large. Therefore, in the structure in which the surge voltage is likely to become large, the advantage of including the zener diode 81 is large.

< modification 3 of the first embodiment >

As shown in fig. 18, only the zener diode 81 may be included instead of the rectifier diode 80. Thus, the zener diode 81 has both a rectifying function and a surge absorbing function. As a result, the number of components of the rotating electric machine 30 can be reduced.

As shown in fig. 19, a plurality of zener diodes 81 may be provided. Fig. 19 shows an example including two zener diodes 81.

< modification example 4 of the first embodiment >

The field winding 73 shown in fig. 20 may also be used. Specifically, the first winding portion 74a is wound around the main pole portion 62, and the second winding portion 74b is wound outside the first winding portion 74 a.

< second embodiment >

In the present embodiment, when the number of turns of the first winding portion 71a is N1 and the number of turns of the second winding portion 71b is N2, "N1 < N2" is set. This setting will be explained below.

The inductance L1 of the first winding portion 71a can be represented by the following equation (eq18), and the inductance L2 of the second winding portion 71b can be represented by the following equation (eq 19).

[ 18 ] of the mathematical formula

[ mathematical formula 19 ]

In the above equations (eq18) and (eq19), μ represents the magnetic permeability, S1 and S2 represent the magnetic path area (cross-sectional area of the magnetic path) of the magnetic path formed when the first and second winding parts 71a and 71b are energized, and m1 and m2 represent the magnetic path length of the magnetic path formed when the first and second winding parts 71a and 71b are energized.

FIG. 21 shows an example where S1/m1 is the same as S2/m 2. Here, the state close to no load is shown, and the magnetic flux passes only through the thin broken line. In this case, in order to make "L1 ═ L2", it is sufficient to make "N1 ═ N2".

However, actually, there is leakage flux like the thick broken line in fig. 21, and due to this leakage flux and the like, S1 tends to be larger than S2, and m1 tends to be shorter than m 2. As a result, S1/m1 became larger than S2/m 2. Fig. 22 shows another example of this case. This example shows a near maximum load condition. When S1/m1 is larger than S2/m2, it is required to make "N1 < N2" so that "L1 is L2".

< third embodiment >

As shown in fig. 23, in the rotor 60, a partition 100 made of a soft magnetic material may be provided between the first winding portion 71a and the second winding portion 71 b. The partition portion 100 is, for example, annular, and a central hole of the partition portion 100 is inserted into the main pole portion 62. The partition portion 100 has a flat shape extending in the circumferential direction when viewed from the axial direction. The first winding portion 71a and the second winding portion 71b are blocked by the partition portion 100 in the radial direction by sandwiching the partition portion 100 between the first winding portion 71a and the second winding portion 71 b. The radial thickness of the partition 100 is smaller than the respective radial thicknesses of the first and second winding portions 71a and 71 b. The circumferential length of the partition 100 is equal to or greater than the circumferential length of each of the winding portions 71a and 71 b.

As shown in fig. 24, the partition portion 100 may be formed by radially stacking soft magnetic bodies. This can reduce eddy current loss. Further, by making the stacking direction radial, the thickness in the radial direction can be set to be thin in accordance with the steel sheet thickness dimension while ensuring the circumferential length of the partition portion 100.

By providing the partition portion 100, most of the leakage magnetic flux flows in the partition portion 100 without flowing through the field winding 70. As a result, it is difficult to generate induced voltages having mutually opposite polarities in the first winding portion 71a and the second winding portion 71b, and further in the partial coils therein, respectively, and to increase the induced current. This can increase the currents induced in the first and second winding portions 71a and 71b in the respective modes 1 to 4 shown in fig. 8.

In the configuration shown in fig. 20, a partition portion may be interposed between the first winding portion 74a and the second winding portion 74 b.

< fourth embodiment >

In the present embodiment, as shown in fig. 25, the field winding 70 is constituted by a series connection body of a first winding portion 71a, a second winding portion 71b, and a third winding portion 71 c. In each main pole portion 62, a first winding portion 71a is wound around the outermost side in the radial direction, a second winding portion 71b is wound around the radially inner side of the first winding portion 71a, and a third winding portion 71c is wound around the radially inner side of the second winding portion 71 b. In each main pole portion 62, the winding directions of the winding portions 71a, 71b, and 71c are the same. The winding direction of the respective winding portions 71a, 71b, 71c wound around one of the circumferentially adjacent main pole portions 62 is opposite to the winding direction of the respective winding portions 71a, 71b, 71c wound around the other.

Fig. 26 shows a rotor-side circuit including the respective winding portions 71a, 71b, and 71c wound around the common main pole portion 62. In this embodiment, the capacitor 90 is referred to as a first capacitor 90.

The rotor 60 is provided with a first capacitor 90 and a second capacitor 91. A first end of the third winding portion 71c is connected to a second end of the second winding portion 71 b. An anode of the diode 80 is connected to a second end of the third winding portion 71 c. The second capacitor 91 is connected in parallel to the third winding portion 71 c. In fig. 26, L3 represents the inductance of the third winding portion 71C, and C1 and C2 represent the capacitance of the first capacitor 90 and the second capacitor 91.

In the present embodiment, the series resonant circuit including the first winding portion 71a, the first capacitor 90, and the diode 80 is referred to as a first series resonant circuit, and the parallel resonant circuit including the second winding portion 71b and the first capacitor 90 is referred to as a first parallel resonant circuit. In the present embodiment, a second series resonant circuit including the first winding portion 71a, the second winding portion 71b, the second capacitor 91, and the diode 80, and a second parallel resonant circuit including the third winding portion 71c and the second capacitor 91 are also configured. When the third resonance frequency, which is the resonance frequency of the second series resonance circuit, is f3 and the fourth resonance frequency, which is the resonance frequency of the second parallel resonance circuit, is f4, the resonance frequencies f3 and f4 are expressed by the following expressions (eq20) and (eq 21).

[ mathematical formula 20 ]

[ mathematical formula 21 ]

The second series resonant circuit and the second parallel resonant circuit function in the same manner as the first series resonant circuit and the first parallel resonant circuit. With this configuration, even when the frequency of the harmonic current flowing through each phase winding 31U, 31V, 31W deviates from the set frequency, for example, if the deviated frequencies are the resonance frequency f3 of the third resonance circuit and the resonance frequency f4 of the fourth resonance circuit, an effect of increasing the excitation current can be obtained at the frequencies. Similarly to f1 and f2, f3 may be set to f 4.

Here, a phenomenon in which the frequency of the harmonic current deviates from the set frequency may occur, for example, in a region where the electrical angular frequency of the rotating electrical machine 30 is high. This is because the higher the electrical angular frequency is, the smaller the number M (M is a natural number) of harmonic currents that can be superimposed in one cycle of the fundamental current is, and the larger the frequency fluctuation when the number of superimposed harmonic currents is changed from M to M-1. For example, in the case where M varies between 4 and 3, there is a fluctuation in frequency of around 30%, and there is a fluctuation in frequency fh of the harmonic current before and after at least around 30%. M — 3 represents a harmonic current in which one cycle of the fundamental current of each of the three-phase currents includes three cycles, and is considered as a minimum unit of the excitation frequency of the excitation winding.

< modification of the fourth embodiment >

The field winding may be formed of a series connection of four or more winding portions. In this case, as shown in fig. 27, when the number of winding portions is n +1, the number of capacitors is n.

< other embodiments >

The above embodiments may be modified as follows.

The inductance L1 of the first winding part 71a and the inductance L2 of the second winding part 71b may be set so as to satisfy any of the above equations (eq3) and (eq4) instead of both of the above equations (eq3) and (eq 4). Specifically, for example, the inductances L1 and L2 may be set so as to satisfy any of "0.5 < L2/L1 < 2" and "0.5 < L1/L2 < 2".

The rotating electric machine is not limited to the inner rotor type rotating electric machine, and may be an outer rotor type rotating electric machine. In this case, the main pole portion protrudes radially inward from the rotor core.

The field winding of the rotor is not limited to an aluminum wire, and may be, for example, a copper wire, a CNT (carbon nanotube), or the like. The field winding may not be formed by compression molding.

Although the present disclosure has been described based on the embodiments, it should be understood that the present disclosure is not limited to the embodiments and configurations described above. The present disclosure also includes various modifications and variations within an equivalent range. In addition, various combinations and modes, including only one element, and one or more or less other combinations and modes also belong to the scope and idea of the present disclosure.