阅读说明：本技术 一种磁场调制式无刷励磁凸极同步电机 (Magnetic field modulation type brushless excitation salient pole synchronous motor ) 是由 王凤翔 于 2020-12-21 设计创作，主要内容包括：本发明涉及一种磁场调制式无刷励磁凸极同步电机,该同步电机包括电源、定子铁心、定子功率绕组、励磁绕组、凸极转子铁心、转子磁场调制绕组,励磁绕组位于定子铁心上,转子磁场调制绕组位于凸极转子铁心上,电源可单独为定子功率绕组和励磁绕组供电。本发明的磁场调制式无刷励磁凸极同步电机结构简单,成本低廉和动态性能好。(The invention relates to a magnetic field modulation type brushless excitation salient pole synchronous motor which comprises a power supply, a stator iron core, a stator power winding, an excitation winding, a salient pole rotor iron core and a rotor magnetic field modulation winding, wherein the excitation winding is positioned on the stator iron core, the rotor magnetic field modulation winding is positioned on the salient pole rotor iron core, and the power supply can independently supply power for the stator power winding and the excitation winding. The magnetic field modulation type brushless excitation salient pole synchronous motor has the advantages of simple structure, low cost and good dynamic performance.)

1. A magnetic field modulation brushless excitation salient pole synchronous motor is characterized in that the synchronous motor comprises a power supply (1), a stator iron core (2), a stator power winding (3), an excitation winding (4), a salient pole rotor iron core (5) and a rotor magnetic field modulation winding (6),

the excitation winding (4) is positioned on the stator core (2),

the rotor magnetic field modulation winding (6) is located on the salient pole rotor core (5),

the power supply (1) can independently supply power to the stator power winding (3) and the excitation winding (4).

2. A field modulated brushless excited salient pole synchronous machine according to claim 1, further comprising a current limiting resistor (10), said current limiting resistor (10) being connected in series with said excitation winding (4) for limiting the current of the excitation winding.

3. A field modulated brushless excited salient pole synchronous machine according to claim 1 or 2, further comprising a transformer (8) controlling the voltage of the excitation winding (4) and a controllable rectifier (9) providing a direct current to the excitation winding (4), and wherein the transformer (8), the controllable rectifier (9) and the excitation winding (4) are connected in series.

4. Magnetic field modulated brushless excited salient pole synchronous machine according to claim 1 or 2, characterized in that the sum of the number of poles of the stator power winding (3) and the excitation winding (4) is equal to the number of poles of the synchronous machine, and the number of poles of the excitation winding (4) is at least 4 greater than the number of poles of the stator power winding (3).

5. Magnetic field modulated brushless excited salient pole synchronous machine according to claim 4, characterized in that the stator power winding (3) is closer to the outer surface of the stator core (2) than the excitation winding (4) in the radial direction.

6. The magnetic field modulated brushless excited salient pole synchronous machine according to claim 4, wherein the salient pole rotor core (5) has a plurality of salient poles (51), the salient poles (51) being for placing the rotor magnetic field modulation windings (6) therein, the number of salient poles (51) being one half of the sum of the pole numbers of the stator power windings (3) and the excitation windings (4).

7. The magnetic field modulated brushless-excited salient-pole synchronous machine according to claim 6, wherein a large slot (511) is provided between every two salient poles (51), a plurality of small slots (512) having different widths and depths are provided on each salient pole (51), the small slots (512) being used to place or wind the magnetic field modulation winding (6),

wherein the large groove (511) and the small groove (512) are both radial, and the central lines of the large groove and the small groove intersect at the center of the rotor rotating shaft in the radial direction.

8. The magnetic field modulated brushless-excited salient-pole synchronous machine according to claim 7, wherein the number of the plurality of small slots (512) is an odd number, the depth and width of the small slot located at the center line of the salient pole are the largest, other small slots are symmetrically distributed on both sides of the small slot at the center line, and the depth and width are gradually reduced.

9. The field modulated brushless-excited salient-pole synchronous machine according to claim 8, characterized in that the rotor field modulation winding (6) is composed of a plurality of self-shorted concentric coils (61), each concentric coil (61) comprises a plurality of multi-turn coils, two sides of each multi-turn coil are respectively placed or wound in different small slots (512) with the center line of the large slot (511) as a symmetry axis, wherein two multi-turn coils respectively coming from adjacent concentric coils are wound in the small slot (512) at the center line of the salient pole (51), and only one multi-turn coil is wound in the small slot (512) at the non-center line.

10. The magnetic field modulated brushless-excited salient-pole synchronous machine according to claim 9, wherein the salient pole (51) has 5 slots (512) of which the first slot (512a), the second slot (512b), the third slot (512c), the fourth slot (512d) and the fifth slot (512e) are arranged in the order from left to right, wherein the third slot (512c) is located at the center line of the salient pole (51) and has the largest depth and width, the second slot (512b) and the fourth slot (512d) are symmetrically arranged at both sides of the third slot (512c) and have the same depth and width and are smaller than the third slot (512c), and the first slot (512a) and the fifth slot (512e) are symmetrically arranged at the left of the second slot (512b) and the right of the fourth slot (512d), respectively, their depth and width are the same and smaller than the depth and width of the second small groove (512b) and the fourth small groove (512 d).

Each of the concentric coils (61) is composed of three multi-turn coils, wherein both sides of a first multi-turn coil (611) are wound in a first small slot (512a) on one salient pole and a fifth small slot (512e) on the left-adjacent salient pole, both sides of a second multi-turn coil (612) are wound in a second small slot (512b) on one salient pole and a fourth small slot (512d) on the left-adjacent salient pole, both sides of a third multi-turn coil (613) are wound in a third small slot (512c) on one salient pole and a third small slot (512c) on the left-adjacent salient pole, respectively, and a third multi-turn coil (613) of two adjacent concentric coils is wound in each of the third small slots (512 c).

11. The magnetic field modulated brushless-excited salient pole synchronous machine according to claim 9, wherein the salient poles (51) have 3 slots (512) of which the depth and width are the largest, and a first slot (512a), a second slot (512b) and a third slot (512c) are sequentially formed in the order from left to right, wherein the second slot (512b) is located at the center line of the salient poles and the first slot (512a) and the third slot (512c) are symmetrically distributed on both sides of the second slot (512b) and have the same depth and width and are smaller than the depth and width of the second slot (512b),

each concentric coil (61) is composed of two multi-turn coils, wherein both sides of a first multi-turn coil (611) are respectively wound in a first small slot (512a) on one salient pole and a third small slot (512c) on the left adjacent salient pole, both sides of a second multi-turn coil (612) are respectively wound in a second small slot (512b) on one salient pole and a second small slot (512b) on the left adjacent salient pole, and a second multi-turn coil (612) of two adjacent concentric coils is wound in each second small slot (512 b).

12. The field modulated brushless-excited salient-pole synchronous machine of claim 1, further comprising a circuit switcher K₁And K₂，

The circuit change-over switch K₁The current limiting resistor (10) is connected to a circuit where the excitation winding (4) is located after the stator power winding (3) is powered on when the motor is started, and the circuit change-over switch K is used for switching on the current limiting resistor₂Is turned off, and the power supply is turned off,

the circuit change-over switch K₂When the synchronous motor is accelerated to be close to the synchronous speed, the excitation winding (4) is switched to a circuit where the excitation winding, the transformer (8) and the controllable rectifier (9) are located, so that the synchronous motor enters a normal working state after being synchronous, and at the moment, the circuit transfer switch K is switched₁Is open.

Technical Field

The invention relates to an electrically excited synchronous motor, in particular to a magnetic field modulation type brushless excitation salient pole synchronous motor.

Background

The electro-magnetic synchronous motor has the advantages of strong overload capacity, high power factor, stable rotating speed and the like, and is widely applied to the fields of high-power compressors, fans, water pumps, rolling mills, ball mills, hydraulic generators and the like. The excitation winding of the traditional electric excitation synchronous motor is placed on a rotor, excitation current needs to be provided through a slip ring and an electric brush, and due to sliding contact, the traditional electric excitation synchronous motor not only needs to be maintained at regular time, but also is easy to generate sparks, and the application of the traditional electric excitation synchronous motor in flammable and explosive places such as coal mines, petroleum and chemical engineering is limited.

The brushless excitation of the electrically excited synchronous motor is an important development direction, and the main design mode of the brushless excitation of the synchronous motor at present is to add an excitation generator on a motor rotor, namely to add a three-phase alternating current generator for rotating an armature on a rotating shaft of the synchronous motor, after the generated alternating current is converted into direct current through a rectifier rotating together with the motor rotor, the direct current is supplied to an excitation winding of the synchronous motor placed on the rotor, the excitation winding of the excitation generator is placed on a stator, the armature voltage of the excitation generator is regulated through a controllable rectifier, and then the excitation control of the synchronous motor is realized. The main structure of the existing brushless excitation synchronous motor is shown in fig. 1, wherein 1 is a power supply, 2 is a stator core of the synchronous motor, 3 is a stator winding of the synchronous motor, 4 is a field winding of the synchronous motor on a rotor, 5 is a component rotating with the rotor of the synchronous motor, 6 is a rotary armature winding of an excitation generator, 7 is a rotor of the excitation generator, 8 is a field winding power supply transformer, 9 is a controllable rectifier for providing a field winding current of the excitation generator, 10 is a current limiting resistor connected in series with a field winding circuit of the synchronous motor when the motor is started, 11 is a field winding of the excitation generator, 12 is a rotary rectifier, and K1 and K2 are circuit change-over switches for starting the motor. Although a slip ring brush is omitted in the brushless excitation mode, an alternating current excitation generator and a rotating rectifier are required to be added, the structure is complex, the manufacturing cost is high, the current of the excitation winding of the synchronous motor needs to be controlled in two stages, and the dynamic control performance is poor.

Disclosure of Invention

Aiming at the defects of the existing brushless excitation synchronous motor, the invention aims to provide a magnetic field modulation type brushless excitation salient pole synchronous motor which is simple in structure, low in cost and good in dynamic performance.

In order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows:

a magnetic field modulation brushless excitation salient pole synchronous motor comprises a power supply, a stator core, a stator power winding, an excitation winding, a salient pole rotor core and a rotor magnetic field modulation winding,

wherein the excitation winding is positioned on the stator core,

rotor field modulation windings are located on the salient rotor cores,

the power supply may separately power the stator power windings and the field windings.

Preferably, the magnetic field modulation brushless excitation salient pole synchronous motor further comprises a current limiting resistor, and the current limiting resistor is connected in series with the excitation winding and used for limiting the current of the excitation winding.

Preferably, the field-modulated brushless-excited salient-pole synchronous machine further comprises a transformer for controlling the voltage of the excitation winding and a controllable rectifier for supplying a direct current to the excitation winding, and the transformer, the controllable rectifier and the excitation winding are connected in series.

Preferably, the sum of the number of poles of the stator power winding and the field winding is equal to the number of poles of the synchronous machine, and the number of poles of the field winding is at least 4 greater than the number of poles of the stator power winding.

Preferably, the stator power windings are closer to the outer surface of the stator core than the field windings in the radial direction.

Preferably, the salient pole rotor core has a plurality of salient poles for placing the rotor magnetic field modulation windings therein, the number of the salient poles being one-half of the sum of the numbers of poles of the stator power windings and the excitation windings. That is, the number of salient poles is one-half of the number of poles of the synchronous motor.

Preferably, a large slot is arranged between every two salient poles, each salient pole is provided with a plurality of small slots with different widths and depths, the small slots are used for placing or winding the magnetic field modulation winding, the large slot and the small slots are radial, and the central lines of the large slot and the small slots intersect at the center of the rotor rotating shaft in the radial direction.

Preferably, the number of the plurality of small grooves is an odd number, the depth and width of the small groove located at the center line of the salient pole are the largest, the other small grooves are symmetrically distributed on both sides of the small groove at the center line, and the depth and width are gradually reduced.

Preferably, the rotor magnetic field modulation winding is composed of a plurality of self-shorted concentric coils, each concentric coil comprises a plurality of multi-turn coils, two sides of each multi-turn coil are respectively placed or wound in different small grooves by taking the central line of the large groove as a symmetry axis, two multi-turn coils from adjacent concentric coils are placed or wound in the small groove at the central line of the salient pole, and only one multi-turn coil is placed or wound in the small groove at the non-central line.

Preferably, the salient pole has 5 small slots, which are a first small slot, a second small slot, a third small slot, a fourth small slot and a fifth small slot in sequence from left to right, wherein the third small slot is located at the center line of the salient pole and has the largest depth and width, the second small slot and the fourth small slot are symmetrically distributed on both sides of the third small slot, and have the same depth and width and are smaller than those of the third small slot, the first small slot and the fifth small slot are symmetrically distributed on the left side of the second small slot and on the right side of the fourth small slot, respectively, and have the same depth and width and are smaller than those of the second small slot and the fourth small slot, each of the concentric coils is composed of three multi-turn coils, wherein both sides of the first multi-turn coil are respectively wound in the first small slot on the salient pole and the fifth small slot on the left adjacent salient pole, and both sides of the second multi-turn coil are respectively wound in the second small slot on the salient pole and the fourth small slot on the left adjacent salient pole, two sides of the third multi-turn coil are respectively wound in a third small groove on one salient pole and a third small groove on the left adjacent salient pole, and a third multi-turn coil of two adjacent concentric coils is wound in each third small groove.

Preferably, the number of the small slots on the salient pole is 3, the first small slot, the second small slot and the third small slot are sequentially arranged from left to right, wherein the second small slot is positioned at the center line of the salient pole and has the largest depth and width, the first small slot and the third small slot are symmetrically distributed on two sides of the second small slot, the depth and width of the first small slot and the width of the third small slot are the same and are smaller than those of the second small slot, each concentric coil is composed of two multi-turn coils, wherein two sides of the first multi-turn coil are respectively wound in the first small slot on the salient pole and the third small slot on the left adjacent salient pole, two sides of the second multi-turn coil are respectively wound in the second small slot on the salient pole and the second small slot on the left adjacent salient pole, and the second multi-turn coil of the two adjacent concentric coils is wound in each second small slot.

Preferably, the magnetic field modulation brushless excitation salient pole synchronous motor further comprises a circuit transfer switch K₁And K₂D, circuit changeover switch K₁The circuit is used for connecting the current-limiting resistor into a circuit where the excitation winding is positioned after the stator power winding is switched on when the motor is started, and the circuit change-over switch K is used for switching on the current-limiting resistor₂Is open; circuit change-over switch K₂When the motor is accelerated to approach the synchronous speed, the excitation winding is switched to a circuit where the excitation winding, the transformer (8) and the controllable rectifier are located, so that the motor enters a normal working state after being synchronous, and at the moment, the circuit change-over switch K₁Is open.

Compared with the prior art, the invention achieves the following remarkable technical effects:

1. the excitation winding of the conventional electrically excited synchronous motor placed on the rotor is transferred to the stator, and power supply through a slip ring and an electric brush is not needed any more, so that brushless excitation is realized, the operation reliability of the motor is improved, and the maintenance cost is reduced.

2. The self short-circuit concentric winding on the rotor does not need power supply, and has simple structure, low cost and reliable operation. The motor starting and load running requirements can be met without additionally adding a starting winding, and the motor has quick excitation control dynamic performance.

3. The number of poles of the stator winding corresponding to the synchronous rotating speed of the magnetic field modulation type brushless excitation salient pole synchronous motor is the sum of the numbers of poles of the power winding and the excitation winding, and the number of poles of the rotor is one half of the number of poles of the rotor of the conventional synchronous motor. Because the number of poles of the stator winding and the number of salient poles of the rotor are reduced, the number of slots of the stator and rotor iron core can be correspondingly reduced, the utilization rate of the iron core and the winding can be improved, and the processing and manufacturing cost of the motor can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the embodiments and the drawings in the prior art, and it is obvious that the drawings described below are only some embodiments of the present invention, and that other drawings can be obtained by those skilled in the art without inventive work.

Fig. 1 schematically shows an example of the main structure of a conventional brushless-excitation synchronous motor.

Fig. 2 schematically shows the main structure of a magnetic field modulation brushless-excited salient pole synchronous motor of one embodiment of the present invention.

Fig. 3 schematically illustrates an embodiment of an end face structure of a salient pole rotor core of the magnetic field modulated brushless excited salient pole synchronous machine of fig. 2 and a rotor magnetic field modulation winding wound thereon.

Fig. 4 schematically illustrates another embodiment of an end face structure of a salient rotor core of the field modulated brushless excited salient pole synchronous machine of fig. 2 and a rotor field modulation winding wound thereon.

Fig. 5 schematically shows an axial structure of a stator core and windings of the magnetic field modulated brushless-excited salient pole synchronous machine of fig. 2.

Fig. 6 schematically shows a partial radial structure of a stator core and windings of the magnetic field modulated brushless-excited salient pole synchronous machine of fig. 2.

Detailed Description

In the description of the invention, the rotor magnetic field modulation winding is used for modulating the magnetic field generated by the stator power winding and the excitation winding current through the magnetic field generated by the rotor magnetic field winding current to obtain an air gap magnetic field with required pole number.

In a preferred embodiment of the invention, the sum of the number of poles of the stator power winding and the field winding is equal to the number of poles of the synchronous machine, and the number of poles of the field winding is at least 4 greater than the number of poles of the stator power winding. The excitation winding and the power winding cannot have the same pole number, otherwise, only electromagnetic coupling is generated between the two windings, and electromechanical energy conversion cannot be realized; if the difference between the pole numbers of the excitation winding and the power winding is 2, the air gap field of the motor is asymmetric, radial unilateral magnetic pull force is generated, and the motor cannot work normally.

The minimum pole number of the magnetic field modulation type brushless excitation salient pole synchronous motor is 8, the pole number can be 8, 12, 16, 20, 24, 24, 28, 32, 36, 40 and the like, and the difference between the adjacent pole numbers is 4. In one embodiment of the invention, the number of poles of the field modulated brushless field salient pole synchronous machine is 12, the number of poles of the stator power winding is 4, and the number of poles of the field winding is 8.

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below with the accompanying drawings.

Example 1

Fig. 2 shows the structure of a 12-field modulated brushless-excited salient-pole synchronous machine. In the embodiment shown in the figure, the synchronous machine comprises a power supply 1, a stator core 2, a stator power winding 3 and an excitation winding 4 located in the stator core 2, a salient rotor core 5, a rotor magnetic field modulation winding 6 (see fig. 3 or fig. 4) located in the salient rotor core 5, a rotating shaft 7 for mounting the salient rotor core 5, a transformer 8, a controllable rectifier 9, a current limiting resistor 10, a circuit changeover switch K₁And K₂。

The motor power supply 1 can supply power to the stator power winding 3 and the excitation winding 4 separately, so that the circuits of the stator power winding 3 and the excitation winding 4 are independent of each other. The motor power supply 1 may be a low-voltage or high-voltage three-phase power supply. The salient pole rotor core 5 may be laminated by electric steel sheets. A transformer 8 is installed in the line supplying the field winding 4 for regulating the voltage of the stator field winding 4. A controllable rectifier 9 is installed in the line feeding the field winding 4 for converting the alternating current output by the transformer 8 into a controllable direct current feeding the field winding 4. The current limiting resistor 10 is connected in series in the circuit of the excitation winding 4 and is used for limiting the current in the circuit. Circuit change-over switch K₁For connecting the current-limiting resistor 10 to the circuit of the excitation winding 4 when closed, the circuit switch K₂When closed, the excitation winding 4 is connected with the circuit of the controllable rectification power supply 9, the transformer 8 and the power supply 1.

Fig. 3 shows an embodiment of an end face structure of a salient pole rotor core of a field modulated brushless excited salient pole synchronous machine of the present invention and a rotor field modulation winding wound thereon. In this embodiment, the number of poles of the synchronous motor is 12, and the number of salient poles 51 of the salient pole rotor core 5 is 6. A large groove 511 is arranged between every two salient poles 51, and 5 small grooves 512 with different widths and depths are arranged on every salient pole 51. The large slots 511 and the small slots 512 are radially arranged, and center lines (not shown in the figure) of the large slots 511 and the small slots 512 intersect at the center of the rotor rotating shaft along the radial direction. The 5 small slots 512 on the salient pole 51 are a first small slot 512a, a second small slot 512b, a third small slot 512c, a fourth small slot 512d and a fifth small slot 512e in sequence from left to right. The third small groove 512c is located at the center line 51' of the salient pole and has the largest depth and width, the second small groove 512b and the fourth small groove 512d are symmetrically distributed on both sides of the third small groove 512c, and have the same depth and width and are smaller than those of the third small groove 512c, and the first small groove 512a and the fifth small groove 512d are symmetrically distributed on the left side of the second small groove 512b and the right side of the fourth small groove 512d, and have the same depth and width and are smaller than those of the second small groove 512b and the fourth small groove 512d, respectively.

The rotor magnetic field modulation winding 6 is composed of a plurality of self-shorted concentric coils, and each concentric coil comprises 3 multi-turn coils: a first multi-turn coil 61, a second multi-turn coil 62 and a third multi-turn coil 63. Both sides of the multi-turn coil 61 are respectively placed or wound in a first small slot 512a on one salient pole 51 and a fifth small slot 512e on the left adjacent salient pole 51 with the center line of the large slot 511 as a symmetry axis, both sides of the second multi-turn coil 62 are respectively wound in a second small slot 512b on one salient pole 51 and a fourth small slot 512d on the left adjacent salient pole 51, and both sides of the third multi-turn coil 63 are respectively wound in a third small slot 512c on one salient pole 51 and a third small slot 512c on the left adjacent salient pole 51. The multi-turn coils of the other concentric coils are also arranged in a similar manner such that the third multi-turn coil 63 of two adjacent concentric coils is wound in the third small slot 512c of each salient pole 51 and only one multi-turn coil (the first multi-turn coil 61 or the second multi-turn coil 62) is wound in the small slot at the non-center line. The advantage of arranging the rotor field modulation winding 6 in this way is that the effective area of the rotor core can be fully utilized, making the air gap field more close to a sinusoidal wave profile.

Fig. 4 shows another embodiment of the end face structure of a salient pole rotor core of a field modulated brushless excited salient pole synchronous machine of the present invention and a rotor field modulation winding wound thereon. In this embodiment, the number of poles of the synchronous motor is 20, and the number of salient poles 51 of the salient pole rotor core 5 is 10. A large groove 511 is arranged between every two salient poles 51, and 3 small grooves 512 with different widths and depths are arranged on every salient pole 51. The large slots 511 and the small slots 512 are radially arranged, and center lines (not shown in the figure) of the large slots 511 and the small slots 512 intersect at the center of the rotor rotating shaft along the radial direction. The 3 small slots 512 on the salient pole 51 are a first small slot 512a, a second small slot 512b and a third small slot 512c from left to right in sequence, the second small slot 512b is located at the center line 51' of the salient pole, the depth and the width of the second small slot are the largest, the first small slot 512a and the third small slot 512c are symmetrically distributed on two sides of the second small slot 512b, and the depth and the width of the first small slot 512a and the width of the third small slot 512c are the same and are smaller than the depth and the width of the second small slot 512 b.

The plurality of self-shorted concentric coils of the rotor field modulation winding 6 comprises 2 multi-turn coils, a first multi-turn coil 61 and a second multi-turn coil 62. Both sides of the first multi-turn coil 61 are respectively placed or wound in the first small slot 512a on one salient pole 51 and the third small slot 512c on the left adjacent salient pole 51 with the center line of the large slot 511 as a symmetry axis, and both sides of the second multi-turn coil 62 are respectively wound in the second small slot 512b on one salient pole 51 and the second small slot 512b on the left adjacent salient pole 51. The multi-turn coils of the other concentric coils are also arranged in a similar manner. Thus, the second multi-turn coil 62 of two adjacent concentric coils is wound in the second small slot 512b of each salient pole 51, and only one multi-turn coil 61 is wound in the small slot at the non-center line.

The number of multi-turn coils of the concentric coils on each salient pole of the salient pole rotor core shown in fig. 3 and 4 is related to the pole number of the motor, the pole number is small for 8-pole and 12-pole motors, the salient pole is wide, and 5-7 small grooves can be arranged on the salient pole. Therefore, each salient pole can be wound with 3-4 multi-turn coils, and for a motor with a large number of poles, the salient pole is narrow, and the number of small grooves which can be formed in the salient pole is small. Thus the number of turns that can be wound per salient pole is also reduced, but at least one turn needs to be in a small slot at the centre line of the salient pole.

Fig. 5 shows an axial section through the stator core 2 and the stator power winding 3 and the field winding 4 arranged thereon, from which the end-face structure of the stator power winding 3 and the field winding 4 can be seen. Fig. 6 shows a partial radial cross-section of the stator core 2 and the stator power windings 3 and the field windings 4 arranged thereon. As is apparent from the arrangement of the stator power winding 3 and the field winding 4 on the stator core 2 shown in fig. 5 and 6, the stator power winding 3 and the field winding 4 may be arranged in the same radial direction of the stator core, and the field winding 4 is arranged at a position closer to the central axis of the stator core 2 than the stator power winding 3, that is, the stator power winding 3 is closer to the outer surface of the stator core 2 than the field winding 4.

The working process of the magnetic field modulation type brushless excitation salient pole synchronous motor comprises the following steps:

when the motor is started, the stator power winding 3 is firstly switched on and then is closed K₁The circuit where the current-limiting resistor 10 and the excitation winding 4 are located is switched on, so that the current of the excitation winding is limited by the resistor connected in series with the excitation winding, the starting torque of the motor is increased, and when the motor accelerates to the speed close to the synchronous speed, the K is switched off₁Closing K₂And the circuit where the excitation winding 4, the transformer 8 and the controllable rectifier 9 are positioned is switched on, and the motor enters a normal working state after synchronous traction.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.