Synchronous motor electric field type excitation coupler, system and rotor position identification method

Abstract

The invention discloses a synchronous motor electric field type excitation coupler, a synchronous motor electric field type excitation system and a rotor position identification method. The synchronous motor electric field type excitation coupler comprises a transmitting polar plate and a receiving polar plate; the height of the concentric circular deep groove in the # imgabs0 # fan-shaped area of the emitting polar plate is lower than that of the concentric circular deep grooves in other areas of the emitting polar plate; the heights of the concentric circular deep grooves in the receiving pole plate are distributed in a staggered mode in a high-low and high-low regular mode with the # imgabs 1 # fan-shaped area as the period, and p is the number of motor pole pairs of the synchronous motor. And determining the electrical angle of the rotor according to the identified coupling capacitance by establishing a mapping relationship between the coupling capacitance between the transmitting polar plate and the receiving polar plate and the electrical angle of the rotor. Based on the improvement of the structure of the electric field type excitation coupler of the synchronous motor, no extra hardware cost needs to be increased while a rotor position sensor which is high in cost and failure rate is omitted, the method has the advantages of economical efficiency and reliability, and the rotor position can be accurately identified within the full-speed domain range.

Description

Technical Field

[0001] The present invention belongs to the field of motors, and more specifically, relates to an electric field excitation coupler, a system and a rotor position identification method for a synchronous motor. Background Art

[0002] Synchronous motors have the characteristics of high power density and small torque pulsation, so they are widely used in many fields such as new energy vehicles and ship electric propulsion. According to the way the rotor magnetic field is established, synchronous motors can be divided into permanent magnet synchronous motors and electrically excited synchronous motors. Compared with permanent magnet synchronous motors, electrically excited synchronous motors do not have the risk of high temperature and vibration demagnetization of permanent magnets, and the excitation magnetic field is flexible and adjustable. They have more advantages than permanent magnet synchronous motors in terms of high temperature reliability, impact resistance and speed-up operation efficiency. Especially after the use of wireless excitation technology to overcome the problem of power supply of the excitation winding, electrically excited synchronous motors have an increasingly broad application prospect.

[0003] At the same time, the ever-expanding application scope and increasingly complex working conditions have put forward higher and higher requirements for the control of electrically excited synchronous motors. High-performance control algorithms such as vector control and direct torque control have overcome the inherent difficulties of nonlinearity and strong coupling in synchronous motor control, and achieved high-performance control of synchronous motors through coordinate transformation, but the implementation process of these control algorithms requires real-time rotor position information.

[0004] Installing sensors such as photoelectric encoders or rotary transformers on the motor rotor shaft is a traditional way to obtain the rotor position. However, the embedded rotor position sensor not only increases the size of the motor, but is also easily damaged, resulting in a significant increase in the maintenance cost of the motor and reduced reliability. To this end, technicians in this field have conducted a large number of studies on sensorless rotor position identification, and according to the motor speed range, two technical solutions, high-frequency injection method and back-electromotive force method, are used respectively.

[0005] (1) Back electromotive force method The basic principle of the back-EMF method is to use the fundamental frequency voltage and current components of the motor to estimate the rotor flux vector and then extract the rotor position information. Since the higher the motor speed, the greater the back-EMF, the greater the signal-to-noise ratio during position extraction and the more accurate the result, the back-EMF method is more suitable for the medium and high speed range of the motor. At medium speeds, the signal-to-noise ratio of the fundamental frequency information is sometimes not enough to obtain accurate rotor position information, and the fundamental frequency information needs to be processed in combination with methods such as model reference adaptation, extended Kalman filter and sliding mode observer. However, the back-EMF method is difficult to avoid the problem of flux trajectory offset and is easily affected by noise.

[0006] (2) High frequency injection method When the motor is stationary or running in the low speed zone, the back electromotive force is too small, and it is difficult to identify the rotor position by detecting the fundamental frequency information. At this time, the high-frequency injection method is required, that is, injecting additional high-frequency signals into the motor windings, and estimating the rotor position by extracting the high-frequency feedback signal. Depending on the type of injected signal, the high-frequency injection method can be divided into high-frequency rotation signal injection, pulsating high-frequency voltage injection, and square wave voltage injection. Among them, high-frequency square wave voltage injection is widely used because it does not require filtering and the system structure is relatively simple. However, the high-frequency injection method has the problem of difficulty in signal extraction and filtering, and cannot be used in control systems with rapidly changing currents.

[0007] In summary, there is currently no synchronous motor rotor position identification technology suitable for the full speed range, and the identification methods within the corresponding speed range are difficult to implement, and the ease of use needs to be improved urgently. Summary of the invention

[0008] In view of the above defects or improvement needs of the prior art, the present invention provides a synchronous motor electric field excitation coupler, a system and a rotor position identification method. Based on the improvement of the structure of the synchronous motor electric field excitation coupler, it eliminates the expensive rotor position sensor with a high failure rate and does not require additional hardware costs. It has the advantages of economy and reliability, and can accurately identify the rotor position within the full speed range.

[0009] To achieve the above object, according to a first aspect of the present invention, there is provided an electric field excitation coupler for a synchronous motor, comprising: At least one pair of emitter plates and at least one pair of receiver plates, wherein the emitter plates and the receiver plates are arranged in a coupled manner; The emitter plate is fixedly connected to the stator of the synchronous motor, and the receiving plate is fixedly connected to the rotating shaft of the synchronous motor rotor, and the receiving plate is driven to rotate by the rotation of the rotating shaft; The emitter plate and the receiving plate are both disc-shaped, and a circular hole is opened in the middle of the emitter plate and the receiving plate. The emitter plate is sleeved on the rotating shaft through the circular hole and does not contact the rotating shaft, and the receiving plate is sleeved on the rotating shaft through the circular hole and contacts and is fixedly connected to the rotating shaft; Concentric circular deep grooves are provided on the surfaces opposite to each other of the emitter plate and the receiver plate, and the concentric circular deep grooves of the receiver plate are embedded in the concentric circular deep grooves of the emitter plate and do not contact each other; The emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; the height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with a periodic high-low pattern, and p is the number of motor pole pairs of the synchronous motor.

[0010] Furthermore, p=4, the emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; the height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with highs and lows in a periodic manner.

[0011] Furthermore, the emitter plate and the receiver plate are both integrally formed whole metal plates.

[0012] Furthermore, the electric field excitation coupler of the synchronous motor includes a plurality of pairs of emitter plates and a plurality of pairs of receiving plates.

[0013] Furthermore, the centers of the emitting plate and the receiving plate are facing each other.

[0014] According to a second aspect of the present invention, there is provided a synchronous motor electric field excitation system, comprising a synchronous motor electric field excitation coupler, wherein the synchronous motor electric field excitation coupler comprises: At least one pair of emitter plates and at least one pair of receiver plates, wherein the emitter plates and the receiver plates are arranged in a coupled manner; The emitter plate is fixedly connected to the stator of the synchronous motor, and the receiving plate is fixedly connected to the rotating shaft of the synchronous motor rotor, and the receiving plate is driven to rotate by the rotation of the rotating shaft; The emitter plate and the receiving plate are both disc-shaped, and a circular hole is opened in the middle of the emitter plate and the receiving plate. The emitter plate is sleeved on the rotating shaft through the circular hole and does not contact the rotating shaft, and the receiving plate is sleeved on the rotating shaft through the circular hole and contacts and is fixedly connected to the rotating shaft; Concentric circular deep grooves are provided on the surfaces opposite to each other of the emitter plate and the receiver plate, and the concentric circular deep grooves of the receiver plate are embedded in the concentric circular deep grooves of the emitter plate and do not contact each other; The emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; the height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with a periodic high-low pattern, and p is the number of motor pole pairs of the synchronous motor.

[0015] Furthermore, p=4, the emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; the height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with highs and lows in a periodic manner.

[0016] Furthermore, the electric field excitation system of the synchronous motor also includes a transmitting side circuit and a receiving side circuit; The emitter plate is electrically connected to the transmitter side circuit, and the receiver plate is electrically connected to the receiver side circuit; The emitter plate and the transmitter-side circuit are fixedly connected to the motor stator of the electromagnetic motor, and the receiver plate and the receiver-side circuit are fixedly connected to the rotating shaft of the motor rotor of the electromagnetic motor.

[0017] According to the third aspect of the present invention, a rotor position identification method for an electric field excitation system of a synchronous motor is provided, a mapping relationship between the coupling capacitance between the emitter plate and the receiving plate and the rotor electrical angle is established, and the rotor electrical angle is determined based on the identified coupling capacitance.

[0018] Furthermore, the transmitting side voltage or the transmitting side current is selected as a test parameter, a mapping relationship between the test parameter and the coupling capacitance is established, and the coupling capacitance is calculated according to the measured value of the test parameter.

[0019] In general, the present invention improves the structure of the electric field excitation coupler of the synchronous motor, and can achieve a one-to-one correspondence between the coupling capacitor and the rotor electrical angle in the same electrical cycle, thus overcoming the limitations of existing motor rotor position identification methods. Compared with the rotor position sensor, the present invention is completely based on the improvement and enhancement of the structure of the electric field excitation coupler of the synchronous motor. It does not require additional hardware costs while eliminating the expensive rotor position sensor with a high failure rate, and has the advantages of economy and reliability. Compared with the existing sensorless position identification method, the present invention does not invade the motor body winding, and the identification accuracy is decoupled from the rotational speed, and can accurately identify the rotor position within the full speed range. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is an overall schematic diagram of an electric field coupled wireless excitation system for a synchronous motor according to an embodiment of the present invention; Figure 2 It is an overall schematic diagram of the electric field excitation coupler of a synchronous motor according to an embodiment of the present invention; Figure 3 A schematic structural diagram of an electric field excitation coupler for a synchronous motor according to an embodiment of the present invention; Figure 4 This is a graph showing the coupling capacitance changing with the rotor angle according to an embodiment of the present invention; Figure 5 Flow chart of a rotor position identification method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] In the description of the embodiments of the present application, "multiple pairs" means two pairs or more than two pairs.

[0023] The naming or numbering of the steps in the embodiments of the present invention does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The execution order of the named or numbered process steps can be changed according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] The embodiments of the present invention provide a synchronous motor electric field excitation coupler, a system and a rotor position identification method, which are described below respectively.

[0026] An embodiment of the present invention provides an electric field excitation coupler for a synchronous motor, comprising: At least one pair of emitter plates and at least one pair of receiver plates, the emitter plates and the receiver plates are coupled and arranged; The emitter plate is fixedly connected to the stator of the synchronous motor, and the receiver plate is fixedly connected to the rotating shaft of the synchronous motor rotor, and the receiving plate is driven to rotate by the rotation of the rotating shaft; The emitter plate and the receiving plate are both disc-shaped, and a circular hole is opened in the middle of the emitter plate and the receiving plate. The emitter plate is sleeved on the rotating shaft through the circular hole and does not contact the rotating shaft, and the receiving plate is sleeved on the rotating shaft through the circular hole and contacts and is fixedly connected with the rotating shaft; Concentric circular deep grooves are provided on the surfaces opposite to the emitter plate and the receiver plate, and the concentric circular deep grooves of the receiver plate are embedded in the concentric circular deep grooves of the emitter plate without contacting each other, so that a coupling capacitor is formed between the emitter plate and the receiver plate to realize energy transmission; Emitter Plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; the height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with a periodic high-low pattern, and p is the number of motor pole pairs of the synchronous motor.

[0027] Due to the change in the height of the slots on the plates, the effective facing area and equivalent capacitance of the transmitting and receiving plates can be changed in the process of rotor rotation. The circumference changes approximately linearly in the manner of "increase-decrease-increase-decrease...", thereby achieving a one-to-one correspondence between the rotor electrical angle and the coupling capacitance within the same electrical cycle. Combined with parameter identification technology, the rotor electrical angle can be obtained online and in real time.

[0028] Furthermore, the emitter plate and the receiver plate are both integrally formed metal plates. For example, the emitter plate and the receiver plate are both made of a whole piece of metal with good conductivity, such as copper or aluminum, and the whole plate can be regarded as an equipotential body when current is passed.

[0029] Furthermore, the electric field excitation coupler of the synchronous motor includes multiple pairs of emitter plates and multiple pairs of receiving plates, that is, adopts a multi-channel parallel connection method, which can increase the excitation power and improve fault tolerance.

[0030] Furthermore, the centers of the emitter plate and the receiver plate face each other. When the centers of the emitter plate and the receiver plate face each other, the slots thereon are staggered and distributed, so that the two can be nested and arranged on the motor shaft without contact, which can increase the effective facing area and increase the coupling capacitance.

[0031] Let's take p=4 as an example.

[0032] Figure 1 The overall schematic diagram of the electric field excitation system of a synchronous motor according to an embodiment of the present invention includes: a DC power supply 4, an inverter 5, a resonant network 6, a transmitter 1, a receiver 2, and a rectifier 7, 8 being the excitation winding of the synchronous motor. The transmitter 1 and the receiver 2 together constitute the electric field excitation coupler of the synchronous motor, which functions to transmit the energy from the transmitting side of the stator to the receiving side of the rotor contactlessly in the form of electric field coupling, supply the excitation winding 8, and generate the main magnetic field of the motor.

[0033] Figure 2 Schematic diagram of the whole body of the electric field excitation coupler of the synchronous motor according to the embodiment of the present invention. This special embodiment corresponds to a 4-pole motor ( ). This special embodiment includes a transmitter 1 and a receiver 2. The transmitter 1 includes two transmitting plates 11 and 12; the receiver 2 includes two receiving plates 21 and 22.

[0034] The emitter plate is fixed to the motor stator and remains stationary during the entire operation of the motor; the receiver plate is fixed to the rotating shaft 3 and rotates coaxially with the motor rotor winding. Furthermore, both the transmitter 1 and the receiver 2 are made of a whole piece of aluminum plate, and the whole plate can be regarded as an equipotential body when current is passed. There is electric field coupling between the transmitter 1 and the receiver 2, which can be regarded as a capacitor, and the AC current can flow normally, thereby realizing the supply of excitation energy from the exciter to the rotor winding.

[0035] Figure 3 The structure diagram of the electric field excitation coupler of the synchronous motor according to the embodiment of the present invention is shown in FIG. The target of the rotor position identification is the rotor electrical angle. According to the basic electromagnetic relationship of synchronous motor, the rotor electrical angle , Mechanical angle and motor pole pairs There is the following relationship between them: ; That is to say, A complete electrical cycle of the pole motor corresponds to A mechanical cycle.

[0036] The receiving side of the synchronous motor electric field excitation coupler is mechanically coaxially fixed with the rotor, and the mechanical period of the two rotations is the same when the motor is working. On this basis, if the structure of the synchronous motor electric field excitation coupler can be designed to make its coupling capacitor The rotor electrical angle can be realized by monotonically changing within a mechanical cycle. One-to-one mapping with coupling capacitance.

[0037] like Figure 3 As shown, in this embodiment, the emitter plate 11 is in the shape of a disk as a whole, and has concentrically distributed circular deep grooves on the surface opposite to the receiving plate 21; at the same time, the height of the grooves on the 1 / 4 sector area of ​​the emitter plate is lower than that of other parts. The receiving plate 21 is also in the shape of a disk as a whole, and has concentrically distributed circular deep grooves on the surface opposite to the emitter plate 11; at the same time, the height of the grooves on the receiving plate is "high-low-high-low" with a 1 / 4 sector area as a period.

[0038] It should be noted that when the pole plate diameter and the number of slots of the synchronous motor electric field excitation coupler remain unchanged, the greater the slot depth, the greater the peak coupling capacitance of the synchronous motor electric field excitation coupler, and the system has a higher excitation power transmission capacity; the greater the difference between the "high" and "low" slot heights, the greater the variation of the coupling capacitance of the synchronous motor electric field excitation coupler within one electrical cycle, which is beneficial to improve the accuracy of rotor position identification, but puts forward higher requirements on the control performance of the excitation control system. It can be designed according to specific needs during use.

[0039] Figure 4 FIG. 1 is a graph showing the coupling capacitance of an embodiment of the present invention changing with the rotor angle. Figure 4 As shown, the rotor mechanical angle rotates During this process, the rotor electrical angle will rotate The coupling capacitance of the synchronous motor electric field excitation coupler changes monotonically in each electrical cycle. This means that the present invention realizes a one-to-one correspondence between the coupling capacitance and the rotor angle in the same electrical cycle through the structural design of the synchronous motor electric field excitation coupler.

[0040] When the wireless excitation system is working, the coupler rotates with the shaft, and its coupling capacitance cannot be directly measured. Therefore, the corresponding rotor electrical angle is also difficult to obtain directly, and needs to be indirectly measured by parameter identification. Therefore, the embodiment of the present invention proposes a rotor position identification method for a synchronous motor electric field excitation system, establishes a mapping relationship between the coupling capacitance between the emitter plate and the receiving plate and the rotor electrical angle, and determines the rotor electrical angle according to the identified coupling capacitance.

[0041] Furthermore, the transmitting side voltage or the transmitting side current is selected as a test parameter, a mapping relationship between the test parameter and the coupling capacitance is established, and the coupling capacitance is calculated according to the measured value of the test parameter.

[0042] Figure 5 This is a flow chart for realizing rotor position identification using electric field excitation coupler of synchronous motor. This method is based on mature parameter identification technology in the field of wireless power transmission and is divided into two steps: modeling and identification: Step 1: Modeling. First, it is necessary to establish an equivalent circuit model based on the actual circuit of the wireless excitation system and analyze it to obtain the mapping relationship between the parameters to be identified and the easy-to-measure parameters. In the electric field wireless excitation system, when the parameter to be identified is the coupling capacitor, the easily measured transmitter voltage and current can be selected as the easy-to-measure parameters to establish the mapping relationship between the transmitter voltage, current and coupling capacitor.

[0043] Step 2: Identification. When the system is working, the voltage and current on the transmitting side are measured in real time, and the coupling capacitance at this time is calculated according to the established mapping relationship; Figure 4 The electric field excitation coupler of the synchronous motor realizes a one-to-one correspondence between the coupling capacitance and the rotor electrical angle in the same electrical cycle. The real-time electrical angle of the synchronous motor rotor can be obtained by looking up the table based on the calculated coupling capacitance.

[0044] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A synchronous motor electric field excitation coupler, characterized in that: include: At least one pair of emitter plates and at least one pair of receiver plates, wherein the emitter plates and the receiver plates are arranged in a coupled manner; The emitter plate is fixedly connected to the stator of the synchronous motor, and the receiving plate is fixedly connected to the rotating shaft of the synchronous motor rotor, and the receiving plate is driven to rotate by the rotation of the rotating shaft; The emitter plate and the receiving plate are both disc-shaped, and a circular hole is opened in the middle of the emitter plate and the receiving plate. The emitter plate is sleeved on the rotating shaft through the circular hole and does not contact the rotating shaft, and the receiving plate is sleeved on the rotating shaft through the circular hole and contacts and is fixedly connected to the rotating shaft; Concentric circular deep grooves are provided on the surfaces opposite to each other of the emitter plate and the receiver plate, and the concentric circular deep grooves of the receiver plate are embedded in the concentric circular deep grooves of the emitter plate and do not contact each other; The emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; The height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with a periodic high-low pattern, and p is the number of motor pole pairs of the synchronous motor.

2. The electric field excitation coupler of a synchronous motor according to claim 1, characterized in that: p=4, the emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; The height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with highs and lows in a periodic manner.

3. The electric field excitation coupler of a synchronous motor according to claim 1, characterized in that: The emitter plate and the receiver plate are both integrally formed whole metal plates.

4. The electric field excitation coupler of a synchronous motor according to claim 1, characterized in that: It includes multiple pairs of transmitting plates and multiple pairs of receiving plates.

5. The electric field excitation coupler of a synchronous motor according to claim 1, characterized in that: The centers of the emitting plate and the receiving plate are facing each other.

6. A synchronous motor electric field excitation system, characterized in that: It includes a synchronous motor electric field excitation coupler, and the synchronous motor electric field excitation coupler includes: At least one pair of emitter plates and at least one pair of receiver plates, wherein the emitter plates and the receiver plates are arranged in a coupled manner; The emitter plate is fixedly connected to the stator of the synchronous motor, and the receiving plate is fixedly connected to the rotating shaft of the synchronous motor rotor, and the receiving plate is driven to rotate by the rotation of the rotating shaft; The emitter plate and the receiving plate are both disc-shaped, and a circular hole is opened in the middle of the emitter plate and the receiving plate. The emitter plate is sleeved on the rotating shaft through the circular hole and does not contact the rotating shaft, and the receiving plate is sleeved on the rotating shaft through the circular hole and contacts and is fixedly connected to the rotating shaft; Concentric circular deep grooves are provided on the surfaces opposite to each other of the emitter plate and the receiver plate, and the concentric circular deep grooves of the receiver plate are embedded in the concentric circular deep grooves of the emitter plate and do not contact each other; The emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; the height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with a periodic high-low pattern, and p is the number of motor pole pairs of the synchronous motor.

7. The electric field excitation system for a synchronous motor according to claim 6, characterized in that: p=4, the emitter plate The height of the concentric circular deep grooves on the fan-shaped area is lower than the height of the concentric circular deep grooves in other areas of the emitter plate; The height of the concentric circular deep grooves on the receiving plate is The fan-shaped area is distributed in a staggered manner with highs and lows in a periodic manner.

8. The electric field excitation system for a synchronous motor according to claim 6, characterized in that: Also includes a transmitting side circuit and a receiving side circuit; The emitter plate is electrically connected to the transmitter side circuit, and the receiver plate is electrically connected to the receiver side circuit; The emitter plate and the transmitter-side circuit are fixedly connected to the motor stator of the electromagnetic motor, and the receiver plate and the receiver-side circuit are fixedly connected to the rotating shaft of the motor rotor of the electromagnetic motor.

9. The rotor position identification method of the synchronous motor electric field excitation system according to any one of claims 6 to 8, characterized in that: A mapping relationship between the coupling capacitance between the transmitting plate and the receiving plate and the rotor electrical angle is established, and the rotor electrical angle is determined according to the identified coupling capacitance.

10. The rotor position identification method of the synchronous motor electric field excitation system according to claim 9, characterized in that: Select the transmitting side voltage or the transmitting side current as the test parameter, establish a mapping relationship between the test parameter and the coupling capacitance, and calculate the coupling capacitance according to the measured value of the test parameter.

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