Dynamic configuration synchronous motor and generator with permanent magnetic poles

Abstract

A dynamically configured device includes a rotor magnetically coupled to a stator through an air gap, and a plurality of sets of phase windings within the stator to generate a first magnetic field in the air gap. The rotor includes a set of permanent magnetic poles and a set of field winding poles configured to generate a second magnetic field in the air gap. A field winding pole has an excitation winding around a pole body and a d-axis reluctance barrier inside or around the pole body such that the d-axis reluctance of the field winding pole is substantially equal to the d-axis reluctance of a permanent magnetic pole.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Application No. 19 / 080,441, filed March 14, 2025, entitled "Dynamically Configured Synchronous Motor and Generator with Permanent Magnet Poles," a partial continuation of U.S. Patent Application No. 18 / 153,555, entitled "Dynamically Reconfigurable Synchronous Motor and Generator," and claims the benefit of U.S. Provisional Application No. 63 / 301,136, filed January 20, 2022, entitled "Dynamically Configured Synchronous Motor and Generator," which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to electric motors, generators, and electric drive systems, and in certain embodiments to innovative technical electronic devices that improve the performance of electric motors / generators and electric drives by dynamically changing the pole and phase configuration of the electric motor / generator and its associated power. Background Technology

[0003] High-performance electric motor and generator systems are widely required in many industrial, automotive, and consumer product applications. There is a strong interest in achieving high-performance and cost-effective motor drive or generator systems. The overall goal is typically to achieve higher power and torque density, as well as higher overall efficiency in motor / generator designs. Multiphase motors, whether used as motors or generators, can generally achieve higher performance than single-phase or three-phase motors in various aspects, including efficiency, power density, torque density, reliability, and cost. Through special arrangements in the design and control of multiphase motors, the number of poles and the number of phases per pole can be dynamically adjusted during operation using dynamic configuration techniques to further improve system performance and reduce costs. Special control architectures such as multi-harmonic field-oriented control (field-oriented (FoC)) can be used to control such dynamically configured drive systems. However, to date, dynamic configuration techniques have been primarily implemented in induction motors, and achieving them in synchronous motors presents a challenge to overcome.

[0004] This disclosure presents innovative techniques for achieving dynamic configuration in various synchronous motors, such as wound-rotor synchronous motors, permanent magnet motors, or hybrid-excitation motors. While the description will be based on electric motors, these techniques can be applied to their generator counterparts or to regenerative operation of the motors. The primary focus will be on addressing the power / torque density and efficiency issues of the motor / generator and drive systems, particularly for applications requiring high performance over a very wide speed range. Summary of the Invention

[0005] High-performance motor drive systems are achieved through dynamic configuration of the number of poles and / or phases of motors and generators, which often solves or avoids these and other problems and usually achieves technological advantages.

[0006] This application discloses a dynamically configured device comprising a rotor magnetically coupled to a stator via an air gap, and multiple sets of phase windings located within the stator for generating a first magnetic field in the air gap. The rotor includes a set of permanent magnet poles and a set of wire-wound poles, the wire-wound poles being configured to generate a second magnetic field in the air gap. Each wire-wound pole has an excitation winding around its pole body, and a d-axis magnetic reluctance barrier is provided inside or around the magnet body, such that the d-axis magnetic reluctance of the wire-wound pole is approximately equal to the d-axis magnetic reluctance of the permanent magnet pole.

[0007] This application also discloses an electrical system including a motor, wherein a stator has a plurality of phase windings, and a rotor is magnetically coupled to the stator through an air gap. The phase windings are configured to generate a first magnetic field in the air gap. The rotor has a plurality of permanent magnet poles and a set of wire-wound poles for generating a second magnetic field in the air gap. An excitation winding is wound around the pole body of the wire-wound pole, and a d-axis magnetic barrier is provided inside or around the pole body, making the d-axis reluctance of the wire-wound pole approximately equal to that of one of the permanent magnet poles. Multiple power inverters are coupled to the multi-phase windings for controlling the phase winding current. A magnetic field current regulator is connected to the wire-wound poles for controlling the excitation winding current.

[0008] This application also discloses a motor control method, including arranging a rotor to have a permanent magnet pole group and a wound magnetic pole group, wherein a wound magnetic pole is placed next to the permanent magnet pole. The method further includes adding a d-axis magnetic barrier inside the wound magnetic pole body to increase its d-axis magnetic reluctance, such that the spatial distribution of a first magnetic field generated in the air gap by the permanent magnet pole and the wound magnetic pole is similar to the spatial distribution near the wound magnetic pole in the operating mode. The method also includes magnetically coupling the stator and rotor through the air gap, and arranging multiple phase windings in the stator, such that the phase windings generate a second magnetic field in the air gap when current flows through them, the spatial distribution of this second magnetic field near the permanent magnet pole being similar to the spatial distribution near the wound magnetic pole in an operating mode.

[0009] One advantage of this invention is that it improves the operating performance of the synchronous motor drive system by changing the number of poles.

[0010] The features and technical advantages of this disclosure have been outlined quite extensively above to facilitate a better understanding of the detailed description that follows. Additional features and advantages of this disclosure will be described below, forming the subject matter of the claims. Those skilled in the art will understand that the disclosed concepts and specific embodiments can be readily used as the basis for modifying or designing other structures or processes to achieve the same purpose as this disclosure. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure as set forth in the appended claims. Attached Figure Description

[0011] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein: Figure 1 Block diagrams of reconfigurable motor / generator systems according to various embodiments of the present disclosure are shown; Figure 2 Examples of multi-harmonic magnetic field orientation control systems according to various embodiments of the present disclosure are shown; Figure 3 A 12-pole arrangement diagram in an electric motor / generator according to various embodiments of the present disclosure is shown; Figure 4 Various embodiments according to this application are shown. Figure 3 The 12-pole arrangement shown is a 4-pole configuration; Figure 5 Various embodiments according to this disclosure are shown. Figure 3 Different configurations of the 12-pole arrangement shown; Figure 6 Exemplary magnetic field waveforms in high pole number configurations according to various embodiments of the present disclosure are shown; Figure 7A Exemplary magnetic field waveforms in low pole number configurations according to various embodiments of the present disclosure are shown; Figure 7B Another exemplary magnetic field waveform in a low pole number configuration according to various embodiments of the present disclosure is shown; Figure 8 Exemplary arrangements of the invariant and reversible groups of the 12-pole arrangement according to various embodiments of the present disclosure are shown; Figure 9A Conceptual diagrams of excitation poles or magnets according to various embodiments of the present disclosure are shown; Figure 9B A conceptual diagram of three excitation poles having an excitation winding is shown according to various embodiments of the present disclosure; Figure 9C A conceptual diagram of six excitation poles having an excitation winding is shown according to various embodiments of the present disclosure; Figure 10AA conceptual diagram of a dynamically configured excitation current according to various embodiments of the present disclosure is shown; Figure 10B Another conceptual diagram showing a dynamically configured excitation current according to various embodiments of the present disclosure is illustrated; Figure 11 A conceptual diagram of a hybrid excitation system having a mixture of excitation poles and permanent magnet poles according to various embodiments of the present disclosure is shown; Figure 12 Block diagrams of excitation control systems according to various embodiments of the present disclosure are shown; Figure 13 A block diagram of a power converter for controlling the excitation current of an excitation winding according to various embodiments of the present disclosure is shown; Figure 14 A device with d-axis reluctance that has controllable excitation poles is shown according to various embodiments of the present disclosure; Figure 15 Different configurations of d-axis reluctance-controlled excitation poles according to various embodiments of the present disclosure are shown; Figure 16 Excitation poles with controllable d-axis reluctance and integrated additional features are shown according to various embodiments of the present disclosure; Figure 17 Excitation magnetic poles with additional conductors and controllable d-axis reluctance are shown according to various embodiments of the present disclosure; Figure 18 Excitation poles with multiple features for controlling d-axis reluctance are shown according to various embodiments of the present disclosure; Figure 19 A rotor with shallow permanent magnet poles according to various embodiments of the present disclosure is shown; Figure 20 The magnetic field of a portion of the air gap surrounding a rotor having shallow permanent magnet poles according to various embodiments of the present disclosure is shown; Figure 21 Exemplary strategies for magnetic field control in shallow permanent magnet pole permanent magnet motors according to various embodiments of the present disclosure are shown; Figure 22 This illustrates a shallow permanent magnet pole rotor integrating features for increasing the d-axis reluctance of the third harmonic magnetic field according to various embodiments of the present disclosure; and Figure 23 Examples of wire-wound magnetic poles with magnetic barriers for increasing the d-axis reluctance of the third harmonic magnetic field are shown according to various embodiments of the present disclosure.

[0012] Unless otherwise stated, corresponding numbers and symbols in the different figures generally refer to corresponding parts. The figures are drawn to clearly illustrate relevant aspects of the various embodiments and are not necessarily drawn to scale. Detailed Implementation

[0013] The manufacture and use of the presently preferred embodiments are discussed in detail below. However, it should be understood that this disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific environments. The specific embodiments discussed are merely illustrative of specific ways of making and using this disclosure and do not limit the scope of this disclosure.

[0014] This disclosure will be described in a specific context with regard to preferred embodiments, namely high-performance electric motors or motor drive systems. These motor drive systems can be applied to a variety of electric or hybrid vehicles, robots, drones, home appliances, wind power generation, industrial drives, and / or other applications. Throughout the description, a dynamically configured wound-rotor synchronous motor is used as an example, but the techniques discussed are generally applicable to other motors, such as permanent magnet motors, hybrid excitation motors, and various generator counterparts. The embodiments will be explained in detail below with reference to the accompanying drawings.

[0015] In electric motors, there is always an inherent conflict between low-speed, high-torque performance and high-speed, high-power operation. For a long time, there has been a desire to improve the performance and cost of motors and motor drive systems by dynamically changing the number of magnetic poles (or simply pole number) during operation in demanding applications. It is well known that specially designed multiphase motors can be reconfigured to operate with different pole numbers and different numbers of phases within a single pole pair by adjusting the phase shift states between phase currents. In dynamically configured motors, the pole number is the number of positive / negative halves of the magnetic field waveform, typically in the air gap (see examples in Figures 6-8). Note that due to the rotational nature of the magnetic field in a motor, the magnetic field waveform may be observed as a spatial waveform taken as a snapshot at a certain point in time, or as a time-varying waveform of the magnetic field strength at a given point. The waveform of the magnetic field can also be indirectly obtained from the voltage of a winding, for example, from the voltage of a phase winding, especially the open-circuit voltage, often allowing observation of the air gap flux waveform. For instance, the waveform of the air gap magnetic field generated by the poles in a synchronous motor can be derived from the waveform of the open-circuit voltage of a phase winding (or a nearby sensing winding). The dynamic configuration of a multiphase motor can be directly achieved in a squirrel-cage induction motor because the current in the squirrel-cage structure can easily follow the magnetic field in the air gap. Therefore, the magnetic field generated by the rotor current in the induction motor naturally has the same number of poles as the magnetic field generated by the stator current. Achieving this in a synchronous motor requires more delicate work, which is the focus of this disclosure. Although the phase windings (sometimes simply referred to as windings) are shown in the stator in this disclosure, this is merely an example illustrating various aspects of the invention. In the design, the roles of the rotor and stator can be interchanged, and the rotor can be inside, outside, or on the side of the stator.

[0016] A motor can have multiple stators and multiple air gaps mechanically separated from each other. Figure 1 shows a topology example of a dynamically configured motor system (DR motor). It is an exemplary multiphase drive system with a multiphase motor having a rotor, stator, and air gaps coupled to a multiphase inverter, which can be used to control the dynamically configured system. The motor has multiple windings arranged in multiple groups, each winding coupled to an output of the inverter. The windings on the stator or rotor can be distributed windings or concentrated windings, and can be either full-pitch or short-pitch windings. We will take the windings on the stator as an example below. The rotor can be located outside the stator as in an external rotor motor, or next to the stator as in an axial flux motor. The inverter can include multiple groups, and each group can have multiple inverter branches coupled to the power supply. The power supplies of the inverter can be isolated from each other, or connected in series or parallel.

[0017] exist Figure 1 In this reconfigurable motor system 100, a stator 104, a rotor 102, and an air gap 103 are included. The rotor 102 may have a squirrel-cage structure or other structures. The stator 104 includes multiple stator windings. The multiple stator windings may be embedded in a stator core. More specifically, the stator core may include multiple slots. Each slot is used to accommodate one stator winding. Alternatively, depending on different application and design requirements, each slot may be used to accommodate multiple stator windings. Furthermore, the reconfigurable motor system may not include a stator core (e.g., a coreless motor), or may have no slots in the stator core.

[0018] like Figure 1 As shown, multiple stator windings can be divided into M groups, where M is a predetermined integer. Each group of stator windings is connected by a connecting ring or a connecting rod. For example, the first group of stator windings S11-S1N is connected by a first connecting ring 151, as shown... Figure 1 As shown. Similarly, the m-th group of stator windings SM1-SMN are connected through the M-th connecting ring 15M, as follows. Figure 1 As shown in Figure 1, the connecting rings are shown as floating (e.g., as shown in Figure 1, the connecting rings are isolated from each other). In this invention, the connecting rings may not be closed in shape and can therefore be connecting rods. If some of the M input power sources are isolated from each other, some of the connecting rings 151-15M can be electrically connected together or form a single connecting ring.

[0019] Furthermore, the reconfigurable motor system 100 includes multiple power converter (or equivalently, inverter) groups. Each power converter group is connected between a power source and a corresponding stator winding group. For example... Figure 1 As shown, the first power converter group 101 is connected between the first power supply VS1 and the first set of stator windings S11-S1N. Figure 1As shown, the first power converter group 110 includes multiple power converters 111-11N. Similarly, the Mth power converter group 1M0 is connected between the mth power supply VSM and the mth stator windings SM1-SMN. Figure 1 As shown, the Mth power converter group 1M0 includes multiple power converters 1M1-1MN. In some embodiments, the multiple power converters are sequentially divided into multiple power converter groups.

[0020] In some embodiments, the power supplies VS1-VSM are independent power supplies as shown in Figure 1. In alternative embodiments, the power supplies VS1-VSM may be connected in series to accommodate high input voltages applied to the reconfigurable motor system 100. Furthermore, the power supplies VS1-VSM may be developed by series-connected capacitors and coupled to a common power supply. Therefore, achieving charge balance between the power supplies may be important. To achieve charge balance among the series-connected power supplies, it is desirable that the DC currents flowing into / out of the power supplies are equal or approximately equal to each other (e.g., within a 20% tolerance).

[0021] In some embodiments, the power supplies can operate efficiently and reliably when the current flowing through each power supply is direct current (DC) or has a low-frequency component. For example, harmonic components of the current (e.g., fundamental and lower harmonics) should be minimized. In some embodiments, each winding should have at least three stator windings evenly spaced between a pair of poles. The stator windings are configured to conduct currents with the same amplitude and frequency. Furthermore, the phase angle of the currents is evenly distributed among the stator windings. In this way, the stator windings in each winding group form a symmetrical, balanced multiphase system, and the current flowing through each power supply is DC under ideal operating conditions.

[0022] During operation, each phase winding is controlled to conduct the desired current. By controlling the current in the phase winding (phase current), or more precisely by controlling the magnetization component of the phase current, a desired magnetic field can be established in the air gap 103 between the stator 104 and the rotor 102. The phase windings can be divided into several groups, each of which can be coupled to the power source through multiple power inverters, which can be configured and controlled as a multiphase inverter as needed. The phase windings can be conductors in slots, or concentrated or distributed windings of various structures. Multiple windings can be connected in series or parallel if required. The inverter can be controlled using field-oriented control of harmonic currents with multiple harmonic frequencies.

[0023] In some embodiments, the reconfigurable motor system 100 has N-phase windings arranged symmetrically in a P-pole configuration in the stator. The number of phases M is equal to N divided by P (N / P). The basic phase shift angle (phase shift) can be expressed as: (1) Compared to traditional structures where the windings within each pair of magnetic poles are fixed by a predetermined structure and design, in situations such as Figure 1 In the dynamically configured structure shown, the number of phases M can be an integer or a non-integer. For example, a motor can have 16 phase windings, which can be configured in six poles. As a result, each pair of poles has 5.33 phases (16 / 3). This is a fractional phase structure. That is, a pole pair may sometimes have five phases and sometimes six phases.

[0024] An advantageous feature of fractional-phase pole structures is the asymmetry between different pole pairs at any given time, and this asymmetry can be advantageously used to generate additional torque similar to the effect of reluctance variation. The possibility of phase-splitting configuration in dynamic configuration (DR) motors provides greater flexibility for improving DR motor design.

[0025] The system can be controlled through multiple harmonic planes, each corresponding to harmonic current / voltage / magnetic flux at different harmonic frequencies. At any given time, one or more harmonic components may exist in the current and voltage of a phase winding. Taking current as an example, in some embodiments, the fundamental frequency component of the current in the i-th phase winding satisfies the following equation: (2) in It is the phase shift angle of the fundamental frequency component.

[0026] In some embodiments, the j-th harmonic component can be represented as: (3) Equation (3) can be simplified to: (4) The phase shift angle of the j-th harmonic component is: (5) In some embodiments, if the j-th harmonic satisfies the following formula, then the j-th harmonic applied to the motor constitutes a balanced system with a pole pair number equal to j multiplied by P.

[0027] (6) The synchronous speed of the j-th harmonic can be expressed as: (7) As shown in formula (7), the synchronous speed S of the j-th harmonic in the DR motor system j It has the same synchronization speed as the fundamental component.

[0028] As current flows through the windings, the magnetic field they generate along the air gap exhibits a repeating waveform pattern. Specifically, along the circumference of the air gap, the magnetic field waveform can be divided into multiple segments, each with a positive and a negative half-wave. Such a segment can be considered a pair of magnetic poles, so the number of segments corresponds to the number of pole pairs, i.e., the number of positive and negative half-waves along the entire circumference of the air gap in the complete waveform. In dynamically configured motors (DR motors), the number of poles can be quickly and smoothly adjusted during operation by changing the phase shift between the currents in adjacent windings, and the motor should be able to operate effectively in all pole configurations designed for operation. For example, if the winding system in the motor is constructed with P poles, a harmonic mitigation motor might operate with 2P poles, 3P poles, etc. Note that each winding may be full-pitch or short-pitch, but care should be taken to use a pitch that provides acceptable performance in all expected pole configurations to produce high torque.

[0029] Mathematically, a DR motor can be modeled and controlled in multiple synchronous dq planes (called harmonic planes). The number of poles of a harmonic plane is proportional to the order of the harmonics, so all harmonic planes have the same synchronous speed. These harmonic planes can be controlled to rotate in the same direction as independent synchronous planes. A DR motor can be designed to efficiently generate torque and transmit power on all or some of the synchronous planes. Typically, each harmonic plane can be handled independently of each other and may independently transmit energy and generate mechanical torque, but not all independent harmonic planes are used for this purpose at any given time. For example, in a 9-phase or 9-winding motor, the 1st (fundamental), 3rd, 5th, and 7th harmonic planes can be controlled independently, but the choice of harmonic group may not be unique. For example, the 1st (fundamental), 2nd, 3rd, and 5th harmonic planes can also be controlled independently. Some or all of these harmonic planes can be used to generate power and torque in certain operating modes, or to control them in other operating modes to obtain better current waveform quality (e.g., setting the 2nd, 3rd, and 5th harmonic current references to zero) to reduce power losses in the inverter, windings, and motor core, as harmonic currents typically cause additional power losses. For example, in a DR motor, the fundamental frequency current, the third harmonic frequency current, and / or the fifth harmonic current can be controlled to generate rotating magnetic fields of the same direction and speed, thereby transferring energy and simultaneously generating torque during steady-state operation or during transitions from one operating mode with a pole configuration to another. At any given time, one or more harmonic planes can be selected to transfer power and / or generate torque. The current references in other independent harmonic planes (inactive harmonic planes) can be set to zero to reduce harmonic power losses in the motor and inverter, or the inactive planes can be left uncontrolled. Different pole and phase numbers can be obtained when the phase shift between the currents in the phase windings can be varied. Magnetic field-oriented harmonic injection techniques can be examined and applied to various pole or phase configurations in such systems.

[0030] To fully utilize the potential of such systems, it is advantageous to implement coordinated field-oriented control (FOC) across multiple harmonic planes. Figure 2 shows an example block diagram of a control system using multiple harmonic planes for the DR motor system shown in Figure 1. The torque setpoint input Tr represents the reference for the system output, obtained according to the current system control objective, and can also be power or other parameters. It may come from the torque command, or from the output of the speed regulator or position regulator in the control system. Changes in Tr cause changes in the current reference value. Figure 2 In this multiphase motor 240, the phase currents (i.e., the currents in the windings of motor 240) I11 to Imn sensed can be converted into synchronization variables Id1, Iq1 to IdK, and IqK, where K is the number of independent harmonic planes through multiharmonic Park and Clarke transformations. Typically, on each harmonic plane, the d-axis component corresponds to the magnetization component, while the q-axis component corresponds to the torque component. The multiharmonic Park and Clarke transformation block 201 is a coordinate transformation mechanism that changes the phase currents with various harmonic contents into values ​​in the dq coordinate system on each harmonic plane. These synchronization variables are DC values ​​during steady-state operation. The transformation matrix used in function block 201 contains trigonometric functions at each harmonic frequency of interest. Note that, assuming a balanced multiphase system, the harmonic components of a specific frequency in the phase current will be converted to DC values ​​in the dq coordinate system with the same harmonic order in the corresponding harmonic plane, while being converted to zero in the dq coordinate system in other harmonic planes. In other words, multiharmonic transformation (MMT) is a filter that removes other harmonic components but transforms the relative harmonic components of current or voltage at the frequency of interest into DC values ​​in the dq coordinate system on the same harmonic plane. For example, in a balanced 9-phase system with four independent harmonic planes, we can choose the first (fundamental), second, third, and fifth harmonic planes as active planes. Through MMT, in steady-state operation, the fundamental component of the phase current will be represented by the d-axis and q-axis constants in the fundamental plane, but their corresponding second, third, and fifth harmonic planes will be zero. Similarly, the third harmonic component of the phase current will be represented by the d-axis and q-axis components in the third harmonic plane, but their contributions to the fundamental, second, and fifth harmonic planes will be zero. In such a system, the current component on each independent harmonic plane can be controlled independently of the current on other harmonic planes.

[0031] Multi-harmonic field-oriented control (FoC) block 202 generates current reference values ​​Idir to Iqir in the dq coordinate system based on the principle of synchronous field-oriented control between different harmonic planes, where i is an exponent in the range of 1 to K. Synchronizing and coordinating power transmission across different harmonic planes can optimize system performance, such as increasing power or torque output while mitigating magnetic saturation in different regions of the motor. Based on the current references in the dq coordinate system across different harmonic planes, multi-harmonic current control block 210 regulates the winding current of motor 230 through multiple current regulators 211 to 21K in harmonic planes 1 to K. The current control block 210 also includes multi-harmonic inverse Parker and inverse Clarke transform functions 220, and generates duty cycle signals D11 to Dmn for the power switches in power inverter 230. The output of power inverter 230 is coupled to the windings of multiphase motor 240, thereby controlling the winding current of motor 240 and producing the desired system output.

[0032] In order to generate torque in the harmonic plane corresponding to a specific frequency of the winding current, the magnetic field generated by the motor rotor along the air gap must have the same harmonic characteristics; that is, the rotor magnetic field must have the same number of spatial poles and must travel at the same speed and in the same direction as the stator magnetic field generated by the winding current. If the stator of the motor is controlled according to the above dynamic configuration principle, the rotor also needs to have a pole-changing structure, so that the change in the number of rotor poles can be synchronized with the change in stator winding current, regardless of how the rotor generates the magnetic field. The focus of this disclosure is pole reconfiguration in motors with wound magnets, especially in synchronous motors. Note that this pole reconfiguration can be applied to both the rotor and the stator, although the following discussion will primarily focus on the magnets in the rotor.

[0033] In a synchronous motor, the rotor has multiple magnetic poles with polarities S and N. The polarity of a magnetic pole is determined by the magnetic flux density it generates in the air gap between adjacent regions. In this invention, when this magnetic flux density (denoted by the symbol B) is positive, the polarity is N (North), and when the magnetic flux density is negative, the polarity is S (South). Figure 3 This is a conceptual diagram of a 12-pole rotor, with 12 magnetic poles (also called magnets, or simply magnetic poles) labeled N or S according to their polarity. Magnetic barriers may be present between the poles to prevent or reduce magnetic field leakage between adjacent poles. Although the poles are shown covering the outer perimeter of the rotor, other pole shapes and arrangements are possible and known in the industry. The inventive aspect of this disclosure does not depend on any details of the pole construction. Figure 4Another conceptual diagram shows the reversal of the polarity of the four magnetic poles of the same rotor. If the magnetic poles are wound magnetic poles, the polarity can be achieved simply by reversing the direction of the current in the excitation windings of these magnetic poles. The magnetic poles with reversed polarity are labeled as the previous polarity / new polarity, such as S / N or N / S. Basically, the magnetic poles are now configured into four groups, with the magnetic poles in each group having the same polarity, so they effectively become a reinforcing magnetic pole. Therefore, by changing the polarity of those four poles, the rotor now effectively becomes a four-pole structure. That is, by adjusting the magnetic field of a group of magnetic poles, the overall shape of the magnetic field is changed, achieving dynamic adjustment of the rotor pole number. Thus, for the same rotor (or motor), Figure 3 shows a high pole number configuration with a large number of poles, and Figure 4 shows a low pole number configuration with a small number of poles. Figure 5 shows the variation in magnetic pole configuration more clearly, where the pole numbering is continuous along the periphery of the air gap. Figure 5(a) shows a 12-pole configuration (high pole number configuration). If the polarities of poles 2, 5, 8, and 11 are changed, the rotor has a 4-pole configuration (low pole number configuration), as shown in Figure 5(b). Other possibilities exist. From the 12-pole configuration shown in Figure 5(a), a 6-pole configuration (medium pole number configuration) can be achieved by changing the polarities of poles 2, 3, 6, 7, 10, and 11, as shown in Figure 5(c). Figure 5 (a) Figure 5 (b) and Figure 5 (c) also referred to herein as Figure 5 Figures 3, 4, and 5 show that different magnetic pole configurations can be achieved simply by changing the polarity of a set of magnetic poles. Furthermore, the amplitude of the magnetic field strength of the magnetic poles can be adjusted to more finely control the magnetic field distribution (which can also be reflected in controlling the harmonic content in the magnetic field waveform), shaping the magnetic field in the air gap for better motor performance. In a motor, the magnetic field in the air gap is most critical for power and torque generation. The total magnetic field in the air gap includes components generated by the current and magnets in the rotor and components generated by the current and magnets in the stator. The magnetic field (or components) generated by the rotor and the magnetic field (or components) generated by the stator interact in the air gap, converting energy and generating torque and power in the motor. To produce consistent torque / power output, both magnetic fields (or magnetic field components) need to have the same number of poles and the same rotational speed. This disclosure focuses more on adjusting the shape of the air gap magnetic field generated by the rotor, including adjusting its number of poles and / or harmonic content, to improve the performance of the motor and drive system. However, it should be noted that the roles of the stator and rotor are interchangeable, so all techniques and constructions applied to one can also be applied to the other. Furthermore, there may be multiple rotors or multiple stators in a motor.

[0034] Different designs can use different numbers of poles, and a design can have a set of implementable poles to suit the application. In this disclosure, we will use the pole number changes from 12 to 4 corresponding to Figures 5(a) to 5(c) as examples to illustrate the concept of pole number reconfiguration.

[0035] It is known in the industry that the magnetic field generated by the rotor can have different shapes along the air gap (also known as spatial magnetic field distribution or simply magnetic field distribution, the shape of which is the same as the waveform of the magnetic field strength seen at a point in the motor's magnetic circuit), such as sine wave, square, trapezoidal, or any other shape. While existing synchronous motors primarily use sine waves, waveforms with significant harmonic content, such as trapezoidal or square waves, can also be used to dynamically configure synchronous motors (motors or generators, abbreviated as DRSM), because multi-harmonic field orientation (FoC) can be used to generate torque in multiple harmonic planes, significantly improving the motor's torque density and power density. Figure 6 shows an example of a 6-pole trapezoidal magnetic field, where the spatial distribution of the magnetic field strength in the air gap below each pole is a trapezoidal half-wave. As mentioned earlier, other waveforms can also be achieved if desired. Figure 6 can be considered half of the 12-pole configuration in Figure 5. In Figure 6, the horizontal axis represents the mechanical distance or angle of the air gap along its circumference, and the vertical axis is the magnetic field strength air gap. The polarity of the magnetic poles in the air gap is also marked accordingly, with positive magnetic density corresponding to N-pole magnets and negative magnetic density corresponding to S-pole magnets. Because motor structures with salient poles (e.g., rotors with internal permanent magnets or salient poles) have significantly lower magnetic field strength near the pole edges, this trapezoidal waveform is easier to generate, meaning there is a large difference in inductance along the d-axis and q-axis. Square-wave magnetic fields are easier to generate using motor structures without salient poles, where the inductance along the q-axis and d-axis is approximately equal (e.g., rotors with surface-mount magnets or circularly wound poles). Of course, the actual shape of the magnetic field can be any other waveform, designed to achieve the performance required for the target application. For example, if desired, a sinusoidal waveform, sometimes with some harmonic components, can be formed by shaping the surfaces of the pole shoes, particularly adjusting the distance between the pole surfaces facing the air gap and adjacent pole shoes, to create an intentionally non-uniform air gap with a suitable shape and bulges, which is well known in the industry. If the polarities of poles 2 and 5 are reversed, the magnetic field is as shown in Figure 7A. Now the structure effectively becomes two poles, still roughly a trapezoidal waveform. The waveform can have a flat top with some fluctuations, or it can be made into other shapes if needed. Since it may contain non-negligible harmonic components, the motor can be controlled using multi-harmonic field-oriented (FoC) control as shown in Figure 2. In Figures 6 and 7A, the positive and negative amplitudes are equal. When using the low pole number configuration corresponding to Figure 7A, sometimes, for example at high speeds, it may be necessary to reduce the high-order harmonic content of the magnetic field generated by the rotor poles in the air gap. This can be achieved by adjusting the relative magnetic field strength under each pole, so that the magnetic field can have more levels to simulate a sinusoidal waveform, such as... Figure 7B As shown, B1 > B2. Figure 7A and Figure 7B In this disclosure, they are also collectively referred to as Figure 7. Generally speaking, as... Figure 6As shown in Figure 7, it is sometimes desirable for the positive and negative halves of the magnetic field to be symmetrical, or even symmetrical along the 45° and 135° lines corresponding to the midpoints of magnetic poles 2 and 5, to control harmonic content. This illustrates the basic concept of dynamic configuration of motor excitation, here on the rotor side. Similarly, other magnetic distribution shapes can be used if desired. Sometimes, it is also desirable to generate asymmetrical magnetic waveforms, which can be easily achieved by adjusting the relative strength of the magnetic fields of these poles.

[0036] like Figure 5 , 6 As shown in Figure 7, between different pole configurations, only some poles undergo polarity changes, while others maintain the same polarity. Therefore, the poles in the motor can be divided into two or more groups, each group having the same change pattern: the first group (constant group) contains poles that do not need to change polarity, and the second group (reversible group) contains those poles that need to change polarity during pole transition. If there are more than two pole configurations (i.e., more than two pole numbers or more than two configurations with different magnetic field strength levels), more than one reversible group (and similarly more than one constant group) can be used. Thus, units that synchronously change polarity or magnetic field strength can be grouped together, simplifying control implementation. In this way, the arrangement and control of different pole numbers or different magnetic field shapes can be viewed as the control of the current in the excitation windings of different pole groups. Figure 8 shows an example. Group A contains poles with constant polarity, called constant poles, and is labeled with their polarity (N or S), while group B contains poles that may need to reverse polarity during operation, called reversible poles, and is labeled S / N or N / S. Similarly, if more precise control over the magnetic field reconstruction is required, it can be divided into more groups.

[0037] Magnetic fields can be generated by permanent magnets (permanent magnet poles), magnetic poles embedded in excitation windings and through which appropriate current flows (excitation poles, or wire-wound poles), or combinations of permanent magnets and excitation poles (hybrid excitation). The permanent magnets and excitation poles can achieve the desired performance through proper design, shaping, and placement, including correct magnetic field strength distribution and suitable salient pole properties. With the advent of memory effect permanent magnets, reversible permanent magnet poles can be made using such magnets and control windings. However, it is currently easier to fabricate reversible poles with excitation poles because the polarity reversal of such poles can be easily achieved by reversing the direction of the excitation current. Figure 9A shows a conceptual diagram of an excitation pole; the black circles represent the conductors of the excitation winding. The magnetic material of the excitation pole includes pole shoes that conduct the magnetic field generated by the excitation winding into the air gap adjacent to the pole. The pole body wound with the excitation winding supports the excitation winding while conducting the magnetic flux. The yoke region connects the magnetic flux generated by the different poles. The magnetic field from the excitation poles is primarily determined by the excitation winding and the current within it. A damping winding can be placed within the excitation poles if desired, but this is optional. The magnetic field distribution formed by the poles in the air gap is mainly determined by the tip (outer surface) of the pole shoe; therefore, the shape of the pole shoe's outer surface should be designed to provide the desired field distribution, including protrusions. If the surface is circular (i.e., part of a circle), the air gap across the pole is uniform, as most stator surfaces are circular, which tends to give a flat distribution, such as in a square or trapezoidal wave magnetic field. However, if the surface of the pole span is shaped to create a non-uniform air gap across the pole span, the magnetic field strength in the nearby air gap can be controlled to follow a specific curve, such as a sinusoidal shape. Thus, by controlling the excitation winding current and / or adjusting the shape of the pole shoe, the magnetic field distribution in the nearby air gap can be shaped, thereby providing good motor performance for the desired operation.

[0038] While it is standard practice to wind the excitation winding around each pole, it may be desirable to wind the excitation winding around multiple poles in a coordinated manner to improve the performance of the motor. Figure 9B An example is shown where two windings are wound around three magnetic poles (which can be considered as...) Figure 6(and half of the magnetic poles in Figure 7). As shown, the excitation winding is placed in the window region 951 between the pole bodies 981 of adjacent magnetic poles. The space 955 between the tips of adjacent magnetic poles has no magnetic material and can be regarded as a magnetic barrier. The starting lead W2+ and the ending lead W2- of winding 2 (whose conductor is represented by a circle filled with dashed lines), marked 983, are wound around magnetic pole 2, and the starting lead W1+ and the ending lead W1- of winding 1 (whose conductor is represented by a circle filled with black lines), marked 982, are wound around magnetic poles 1, 2, and 3. In a high pole number configuration (multiple poles), the current (Iw1) in winding 1 and the current (Iw2) in winding 2 should be arranged so that the ampere turns of winding 1 and winding 2 are the same but the polarities are opposite (i.e., Iw1 is positive, but Iw2 is negative, that is, the directions of Iw1 and Iw2 are opposite). In a low-pole configuration, the polarity of pole 2 can be changed by reversing Iw2 (i.e., both Iw1 and Iw2 are positive or in the same direction), and the amplitudes of Iw1 and Iw2 can be adjusted to give the desired magnetic field waveform, as shown in Figures 7A and 7B. A particular advantage of this arrangement is that the conductor in each window region carries current in only one direction, resulting in lower power loss for the windings at the same magnetic field strength compared to an arrangement where each magnetic pole is wound with an excitation winding. Figure 9C It shows Figure 3 and 4 The view shown is of half of the rotor, cut along one perimeter to expose the excitation windings and magnets, where poles 4 to 6 are added. Figure 9B In the configuration. Figure 9CIn the diagram, each pole body 981 is represented in light gray, the small windings 983 and 985 that only wrap around one pole body are represented in black, and the large windings 982 and 984 that wrap around three pole bodies are represented in dark gray. The number of turns in each winding can be designed according to system requirements and can be different from each other. However, all windings connected in series or parallel should be designed to have the same current or voltage. Winding 3 (984) (starting lead W3+, ending lead W3-) is wound on pole 5, and winding 4 (985) is wound around poles 4, 5, and 6. Winding 1 (982) and winding 3 (984) reverse the connection of W1- and W3-, so that the current in windings 982 and 984 is the same in magnitude but opposite in direction. Connecting W2- and W4- reverses the connection of windings 2 (983) and winding 4 (985), so that the current in windings 983 and 985 is the same in value but opposite in direction. Of course, windings 1 and 3 can also be connected in reverse parallel, as can windings 2 and 4. This connection method can be extended to other poles of the motor. By connecting multiple excitation windings in series and parallel in the motor, excitation windings with the same changing pattern can be combined together, making current control easier. Note that the magnetic material in poles 2 and 5 may have a shorter length to accommodate more conductors from the ends of rotor excitation windings 982 and 983 or 984 and 985. It is well known that the magnetic material of the poles can be silicon steel sheets, ferrite, iron powder, or other magnetically conductive materials formed through various suitable processes.

[0039] We will illustrate the pole-changing process using a scenario where all magnetic poles are excitation poles. In Figure 10, the current number refers to the number of the excitation winding corresponding to the magnetic pole (i.e., I1 represents the current in the excitation winding of pole 1). Before t0, the rotor and motor are in a low-pole configuration. At t0, the system begins pole-changing, and the excitation current begins to change. The excitation winding current in the constant magnetic poles (poles 1, 3, 4, 6, etc.) does not change direction during this process, while the current in the commutating poles (poles 2, 5, etc.) changes direction during this pole-changing process. With proper control, the current can be gradually changed to achieve a smooth transition. The figure shows a linear transition, but other shapes of transitions, such as sinusoidal transitions, are also possible. At t1, the motor reaches the end of the transition, and the system reaches the desired high-pole configuration. Because the excitation winding current transitions smoothly during the transition, there are significant magnetic field strengths in both the cut-out and cut-in harmonic planes. Therefore, significant harmonic content exists in the phase winding current / voltage and the motor magnetic field during this transition. The stator current can be controlled using the principle of multi-harmonic field-oriented control (FoC) to generate torque on two harmonic planes when needed and to control the total torque generated by the motor during the transition. The stator current can be controlled synchronously, ensuring that the sum of torques generated on all active harmonic planes remains approximately the same or follows the desired pattern. The motor output can remain continuous or even constant during the pole-changing transition, thus avoiding significant disturbances caused by the pole-changing action. At t3, the system begins another pole-changing transition, similar to the transition between t0 and t1, but in the opposite direction. In Figure 10A, winding currents I1, I3, I4, and I6 are shown as equal, and I2 and I5 are also equal. These currents can have different values ​​if needed. Figure 10B shows a similar process, but the excitation windings are connected in two groups, winding W1 and winding W2, in a manner similar to that shown in Figures 9B and 9C. By appropriately grouping the excitation windings, the number of controllable currents is much lower than the number of poles, thus reducing system cost. Although two groups are indicated in Figure 10B, more groups are possible if needed.

[0040] This pole-changing operation can be applied to various motor topologies and configurations. Note that, as shown in Figure 7, the amplitude of the reversible pole excitation current affects the intensity of magnetic field harmonics in the air gap during both low and high pole number configurations, and can be used to inject third harmonics or other harmonics during steady-state operation to optimize system performance. For example, when the required torque is not very high, by increasing the magnetic field of the reversible poles to be higher than that of the constant poles, the third (and possibly other higher-order) harmonic components can be reduced (and the shape of the pole shoe surface can be designed as needed to reduce such harmonic content), thus reducing motor power losses and improving motor and system efficiency. In this way, the motor can operate with a more sinusoidal current and air gap magnetic field in the low to medium torque range, significantly improving system efficiency in applications such as electric vehicles. When the required torque is higher, the excitation current can be adjusted to generate an appropriate amount of harmonic content in the air gap (and in the rotor and stator) magnetic field, and coordinated with multi-harmonic control of the stator windings to reduce magnetic saturation in certain areas of the rotor and / or stator, generating more torque in multiple harmonic planes, thus significantly improving the motor's torque and power capabilities.

[0041] Although the preceding discussion assumed that the current in the excitation winding was DC during steady-state operation, it is also feasible to feed an AC current with appropriate frequency, phase, and amplitude into the excitation winding to establish a rotating magnetic field, thus making the motor a wound-rotor induction motor or a doubly-fed induction motor. The pole reconfiguration principle discussed earlier can still be applied to this type of motor.

[0042] Constant poles can also be achieved using surface-mount or embedded (embedded) permanent magnet configurations with various permanent magnet arrangements, while reversible poles use excitation poles. Figure 11 shows an example with internal permanent magnets and excitation poles with V-grooves. If desired, the area around the tip of the excitation pole (shown as shaded areas) can be filled with a non-magnetic material, such as a plastic compound, glue, or epoxy resin. Alternatively, the same or different non-magnetic materials can be incorporated into the space between the excitation winding or, optionally, the damping winding. Non-magnetic materials can improve the mechanical strength and integrity of the poles and / or windings, and can also be designed to conduct heat and provide cooling for the poles and / or windings. The shape of the pole shoes (especially their surfaces) of the reversible poles should be designed to match the permanent magnet poles so that the d-axis and q-axis inductances of these poles have similar values ​​to facilitate smooth torque and current control, which can be used... Figure 2 The multi-harmonic field-oriented (FoC) control principle is illustrated. In this hybrid excitation rotor, in addition to changing the number of poles as discussed previously, the amplitude of the excitation winding in the reversible poles can also be adjusted to control the amount of harmonic injection into the magnetic field. Furthermore, intentionally reducing the amplitude of the excitation current in the reversible poles can also reduce the fundamental component of the air gap flux, thereby achieving a field-weakening effect. This can be advantageously used in certain designs.

[0043] The amplitude of the excitation current affects not only the rotor flux linkage but also, as shown in Figure 7, the harmonic content of the magnetic field in the air gap. During steady-state operation, the desired magnetic field waveform can be generated by increasing or decreasing the harmonic content of the motor's magnetic field through controlling the current in the excitation winding, especially the current in the reversible poles. This improves the motor's torque and power while optimizing performance indicators such as power loss or efficiency. Since the magnetic field in the air gap is primarily established by the phase winding current and the excitation winding current, the excitation current and the excitation current should be coordinated and determined based on better system performance (typically system or motor efficiency). It should be noted that using the excitation winding current to generate the desired harmonic content in the air gap flux is generally more efficient than generating it through the phase winding current, thus contributing to higher motor efficiency. Therefore, whenever possible, it is best to use the excitation current as the primary means of generating harmonic flux and adjust the phase current accordingly when necessary. Furthermore, if the rotor poles generate unwanted harmonic components in the air gap and stator magnetic fields, the harmonic currents of the phase windings can be controlled to weaken these harmonic components in the air gap and stator magnetic fields. By using multi-harmonic field orientation (FoC) control, greater torque can be generated on each harmonic plane by utilizing the harmonic content in the magnetic field.

[0044] Dynamic configuration of the synchronous motor control can be achieved by combining the multi-harmonic field-oriented (FoC) principle shown in Figure 2 with current regulation in the excitation winding. If the excitation winding is located in the rotor, slip rings and / or wireless power transfer (WPT) can be used to bring the excitation energy to the winding on the rotor. By combining excitation windings with the same variation pattern, power transfer to the excitation winding can be greatly simplified. Figure 12 shows an exemplary excitation current regulator for controlling the current in the excitation winding, where W1 to W6 are the excitation windings of poles (or pole groups) 1 to 6, and SR1, SR2, and SR3 are three slip rings. The windings in the rotor can be arranged in series and parallel to reduce power supply interconnections. Figure 12In this configuration, W2 and W5 are connected in parallel to form a reversible group 1203. W1 and W4 are connected in series to form one branch, and W3 and W6 are connected in series to form another branch. These two branches are connected in parallel to form a constant group 1204. Power switches Q1 and Q2, together with inductor L1 and capacitor C1, form a buck converter 1201 with output V1. Power switches Q3 and Q4, together with inductor L2 and capacitor C2, form another buck converter 1202 with output V2. Other power converter topologies can be used in power converters 1201 and / or 1202 if desired. The controller controls the power converter to generate current for the windings. Typically, the windings of the constant group can be connected between the output of the power converter and the power rail (P or N), while the windings of the reversible group can be connected between the outputs of two or more power converters, thus the output voltage of the power converter can be configured to provide the correct voltage for different winding groups. The power converter can be located in or outside the rotor. In Figure 12, assuming the power converter is located outside the rotor, slip rings SR1 to SR3 are used to transfer power from the output of the power converter to the windings. Typically, 3 or 4 slip rings are sufficient for a rotor with a dynamic configuration. Of course, the winding interconnections can have different patterns to suit a specific design, and different ways of arranging the power converter are possible. For example, the power converter can be located inside the rotor. Furthermore, if needed, the full-bridge converter can change the direction of the current while controlling the current amplitude via PWM and other control mechanisms. If wireless power transfer is used to transfer excitation power to the rotor, it is best to use a high frequency (e.g., in the MHz range) to reduce the size and weight of the receiver, while also reducing power losses in the motor's metal materials in the presence of the magnetic field of the WPT system. Figure 13 A full-bridge converter 1301 consisting of four power switches Q1 to Q4 is shown as an example. This structure can simultaneously control the magnitude and direction of the current Ip in the excitation winding Wp (1302), where the excitation Wp can physically be multiple excitation windings connected in parallel or series. Although the excitation windings in the figure are located on the rotor and conduct DC current, in practical applications they may be located on the stator and conduct AC current.

[0045] In rotors that combine permanent magnet poles and wound magnetic poles (such as...) Figure 11As shown, the permanent magnet poles and wound poles need to have equal or approximately equal magnetic reluctance in the d-axis and q-axis directions (e.g., within ±25% tolerance). This ensures that when the motor operates in a high-pole configuration, the magnetic field behavior of the permanent magnet poles and wound poles in the air gap will be similar. The magnetic field generated by the stator phase windings will exhibit the same or similar spatial distribution in the air gap near the permanent magnet poles and wound poles. The spatial distribution of the magnetic field generated by the rotor poles in the air gap near the permanent magnet poles and wound poles will also be the same or similar. Since the magnetic reluctance of the permanent magnet poles in the d-axis direction is higher than that in the q-axis direction (opposite to traditional wound poles), special structures need to be added inside or around the wound poles to make their magnetic reluctance characteristics close to those of the permanent magnet poles. Because the d-axis magnetic reluctance of traditional wound poles is usually low, resulting in a much higher d-axis inductance than the q-axis inductance, it is necessary to significantly increase the d-axis magnetic reluctance of the wound poles, such as... Figure 11 As shown. Figure 14 An example of such a reluctance regulation mechanism is illustrated, in which the dimensions and shapes of the d-axis magnetic barrier 1401 and the excitation winding chamber 1403 can be appropriately configured to provide a suitable d-axis reluctance value for the wire-wound magnetic poles shown in the figure. 1403 both provides a location for the excitation winding and constitutes a magnetic barrier (of course, 1403 can also be configured as a magnetic barrier independent of the excitation winding chamber). The d-axis magnetic barrier can increase the d-axis reluctance of the wire-wound magnetic poles, and it can be implemented as a cut or opening on the rotor and / or pole body. The rotor or pole body structure can be a component made of solid magnet steel or a stack of silicon steel sheets. The dimensions and shape of the magnetic barrier can be adjusted according to design requirements, but the magnetic barrier should not completely cut off the rotor / pole body; it is best to retain the body bridging component 1402 to achieve mechanical connection of the rotor / pole body parts at the necessary locations. The shape design of the excitation winding chamber 1403 also enables it to function as a magnetic barrier, used to reduce magnetic flux leakage between adjacent rotor poles. For example, Figure 14 The extra space 1404 in the upper left corner of the intermediate excitation winding chamber can be regarded as a magnetic barrier structure designed specifically to reduce inter-pole flux leakage.

[0046] The d-axis magnetic barrier can be configured as a multi-component structure. Figure 15 The d-axis magnetic barrier 1401 is implemented through two cuts on the pole body. Figure 16 This indicates that other structures, such as cooling component 1601, can be added to the cut. The cooling structure can take the form of pipes filled with coolant, heat pipes, or heat-conducting metal plates. Furthermore, such as... Figure 17 As shown, a portion of the excitation winding and other conductors can also be placed inside the cut of the d-axis magnetic barrier. This is an example demonstrating that, through a specially constructed winding chamber, the d-axis magnetic reluctance of the wire-wound magnetic pole can be much higher than the q-axis magnetic reluctance. This is a design that integrates the magnetic barrier and the excitation winding chamber.

[0047] In practical applications, rotors are often weight-reducing by using weight-reduction cuts. For example... Figure 18As shown, cut 1802 can serve as a weight reduction cut. A large cut 1801 at or near the wire-wound magnetic pole body can simultaneously serve as a weight reduction cut and a d-axis magnetic barrier. Note: Although the illustration uses a rectangular structure to represent the d-axis magnetic barrier, any shape or combination of different shapes can be used to achieve this function.

[0048] The aforementioned magnetic barrier technology can be applied to any motor with a hybrid permanent magnet pole and a pole with a different structure, regardless of whether the number of poles changes during operation. On the other hand, for motors with variable pole numbers, such as the aforementioned dynamically reconfigurable synchronous motor, the magnetic barrier technology can achieve the required magnetic flux distribution in the air gap in both high-pole and low-pole configurations.

[0049] The stator windings can be distributed or concentrated, depending on system requirements. Concentrated windings are easier to manufacture and less expensive. Using a dynamically configurable synchronous motor, the number of poles can be adjusted to provide better system performance. For example, at very low speeds, a high-pole configuration can be used to increase the frequency of the winding current, which makes parameter identification and / or sensorless control easier. When very high torque is required, a high-pole configuration with near-square wave current and magnetic field can be used, thus significantly reducing the motor size compared to existing technologies. At high speeds, a low-pole configuration with current and magnetic field closer to a sinusoidal waveform can be selected. The harmonic content in the winding current and the magnetic field in the air gap can be reduced by controlling the amplitude of the excitation current in the reversible poles, as shown in Figure 7B, thus achieving high efficiency. Please note that changes in the stator pole number (the number of poles of the magnetic field generated by the current and magnets in the air gap in the stator) should be synchronized with changes in the rotor pole number (the number of poles of the magnetic field generated by the current and magnets in the air gap in the rotor). Ideally, the pole transitions in both the stator and rotor should be coordinated and synchronized to ensure that the output torque follows the desired pattern during the transition, thus avoiding significant disturbance to the system user. As previously mentioned, dynamic configuration techniques can be implemented using multi-harmonic field-oriented (FoC) control with appropriate excitation current control. This technique can be advantageously used to improve system efficiency while reducing system size, weight, and cost. Because multi-harmonic field-oriented (FoC) control coordinates torque generation at different frequencies, it can also be used to reduce ripples in mechanical torque, thereby improving the noise and vibration performance of the motor and motor drive system.

[0050] Considering that different pole numbers correspond to different harmonic orders of the spatial flux in the air gap on the rotor surface, a dynamically configured synchronous motor is essentially a synchronous motor capable of operating using different harmonic components of the air gap flux. In reality, multiple orders of harmonics may coexist in the spatial flux of the air gap within the motor, such as in the low-pole configuration discussed earlier. In certain applications, the amplitude of higher-order components in the air gap flux can be intentionally increased to gain advantages. For example, an appropriate third harmonic can be added to the air gap flux to achieve a higher total flux linkage containing both the fundamental and third harmonic components, significantly improving the motor's torque and power density. The key lies in the rational configuration of permanent magnet poles and wound poles to obtain ideal air gap harmonic components. The arc length and the convexity of the wound poles can be used to adjust the relative intensity of the harmonic components.

[0051] As is well known, surface-mount permanent magnet (SPM) rotors contain high harmonic components in their air gap flux, making it difficult to maintain good performance over a wide speed range. Furthermore, in traditional three-phase systems, the third harmonic flux in the air gap of an SPM motor cannot be used to generate torque because the motor phase winding current does not contain a third harmonic component. In contrast, integrated permanent magnet (IPM) rotors typically employ a deep V-shaped pole arrangement, resulting in low harmonic content in their air gap flux and maintaining reasonable performance over a wide speed range. To achieve even better performance, [further details can be added]. Figure 19 The shallow magnet structure shown realizes permanent magnet poles. This structure can enhance the harmonic components of the air gap flux and operate efficiently in deep magnetic weakening mode, thus maintaining excellent performance over a wide speed range. Figure 19 Configuration A illustrates a shallow magnet structure consisting of two magnetic segments 1904 and 1905, which can be symmetrical or asymmetrical. Each segment can be a straight line filled with a set of magnets, leaving a small gap as a magnetic barrier. Other shapes or different numbers of segments can also be used. The two segments 1904 and 1905 can be achieved by slotting a core of silicon steel or other suitable material and embedding permanent magnets within the slots. Additional magnetic barriers can be added. The height of the pole is much smaller than its width; for example, the ratio of magnet height to width can be less than 1 / 4. In this way, a good balance is achieved between harmonic content and rotational speed range. Configuration B shows an example of combining two segments into a single structure. Note the barriers and magnetic bridges and / or magnetic barriers that can be added to the pole structure as needed to further shape the reluctance characteristics of the d-axis and q-axis and / or enhance the mechanical integrity of the poles. For example, magnetic barriers 1901 and 1902 can be added to the pole structure, as shown in Configuration B. Magnetic barriers 1901 and 1902 can be arranged symmetrically or asymmetrically, depending on the design requirements.

[0052] Shallow magnet structures can utilize harmonic components to smooth the magnetic flux distribution in the motor's air gap, making the waveform top of the magnetic flux density in the air gap tend to be flat or nearly flat (for example, controlling the fluctuation amplitude to within 20%, except for high-frequency fluctuations caused by the cogging effect). Figure 20 As shown. In Figure 20 In the diagram, the X-axis represents the spatial angle along the circumference of the air gap, and the Y-axis represents the magnetic flux density in the air gap (ignoring fluctuations caused by the slotting effect). Figure 20 The magnetic flux distribution shown has a flat top 2001, with positive and negative values ​​corresponding to the N (north) and S (south) poles, respectively. The flat top is connected by a transient transition region 2002; although illustrated as a linear transition, the actual transition shape may vary. The flat-top waveform can reduce the maximum magnetic flux density in the motor, thereby alleviating magnetic saturation in the motor's magnetic circuit and achieving high torque and power density. On the other hand, as with flat-top waves... Figure 20 The configuration shown contains strong third harmonic components, requiring proper configuration of the phase winding current control to effectively utilize the third harmonic flux while minimizing its side effects. For example, the phase current should contain an appropriate third harmonic component to generate greater torque output while reducing power losses caused by the third harmonic current and flux. Since conventional star-connected three-phase motors cannot generate third harmonic currents in their phase windings, a higher number of phases and / or special winding structures are needed to achieve the flow of subharmonic currents, such as delta windings, open-circuit windings, or winding neutral points.

[0053] Therefore, effective strategies are needed to control the third harmonic component in the air gap flux and phase current. Typically, at low torque demands, it is unnecessary to utilize the third harmonic component in the winding current and flux to generate high torque. Instead, priority should be given to reducing power losses – especially in the high-speed operating range, as winding resistance and core losses both increase with frequency (i.e., motor speed). In this case, a negative excitation component can be introduced into the winding current at the third harmonic and / or higher harmonic frequencies to reduce the corresponding harmonic components in the air gap and stator flux. Simultaneously, a torque component of the corresponding frequency can be added to the winding current to generate torque. The relative strength of these harmonic components to their fundamental component can be determined by minimizing the power losses of the motor and / or drive system under given torque and power output conditions. When the speed exceeds a certain value, the third harmonic excitation current can be configured to reduce the third harmonic flux in the stator core to zero or near zero (e.g., below 25% of the original value generated by the permanent magnet). At this point, the torque component at the third harmonic frequency can be controlled to generate the required torque, thereby minimizing the total power loss of the motor or drive system for a given drive system output power.

[0054] When the required torque is very high, it may be necessary to fully utilize the fundamental and harmonic components (mainly the third harmonic component in actual motors) of the rotor flux (i.e., the air gap flux contributed by the rotor poles) to generate maximum torque. In this case, the maximum torque output can be achieved while keeping the total current constant by optimizing the amplitude and phase of the harmonic current relative to the fundamental frequency current. This is similar to the "maximum torque per ampere" control strategy in traditional motor drives—this optimization is only implemented for the fundamental frequency current in traditional solutions. Alternatively, the optimization objective can be changed to generate the maximum torque under certain power losses, where power losses can be defined as: motor power losses, inverter power losses driving the motor, total power losses of the drive system (i.e., losses of the inverter plus the motor), or power losses of a key component (such as power semiconductor devices in the inverter, motor phase windings, or motor rotor power losses). Specific performance parameters can also be selected as optimization indicators based on system requirements.

[0055] Figure 21 A strategy embodying the aforementioned control logic is illustrated, using the excitation components (typically denoted as Id) at the fundamental frequency (1f) and third harmonic frequency (3f) of the phase current as an example. As previously mentioned, the torque components at these frequencies are determined based on the required torque / power and optimization objectives. Of course, more harmonics, such as the fifth and seventh harmonics, can be considered if necessary. Furthermore, if there is significant asymmetry in the magnetic pole design, similar logic can be incorporated into flux control at even harmonics (such as the second and fourth harmonics). To flexibly utilize harmonic magnetic fields under different operating modes or configurations, the phase winding current can be adjusted according to the field-oriented control principle for different harmonic frequencies, and different optimization objectives can be set for each operating mode.

[0056] Please note that with this flux control logic, most of the motor torque will be generated at the fundamental frequency. However, higher harmonic flux helps increase the amplitude of the fundamental frequency flux linkage when high torque is required without oversaturating the stator core, and / or reduces power losses caused by high-frequency flux in the stator core. To maintain good efficiency while increasing the motor's power / torque density, it is important to ensure that the torque generated in the higher harmonics (sometimes called the higher harmonic plane) is in the same direction as the torque generated at the fundamental frequency. This requires that the magnetic reluctance of the poles on the d-axis and q-axis be the same in the higher harmonics as in the fundamental frequency mode (this is essentially similar to the characteristic of low-convexity IPM motors, where the d-axis reluctance is higher than the q-axis reluctance). For example, to utilize the third harmonic magnetic field in the motor (actually the air gap or rotor), the key is to increase the magnetic reluctance of the third harmonic magnetic field d-axis flux path in the rotor. Figure 22 This illustrates the basic principle: one magnetic pole is equipped with three magnetic barriers 2201, 2202, and 2203. Other magnetic poles should be configured with the same or similar magnetic barriers, which are not shown in the diagram for simplicity. The three magnetic barriers 2201, 2202, and 2203 should possess the same... Figure 14-17The same or similar characteristics may have the same or different shapes and sizes. If the angular offset between adjacent magnetic poles is ϴm, then the positions of barriers 2201 and 2203 should be approximately centered at ϴm / 3, which corresponds to the d-axis of the third harmonic magnetic field. Of course, the magnet structure can adopt different shapes. Figure 22 Another multi-segment magnetic pole structure with angular offset was also demonstrated, but the principle of using magnetic barriers to shape the higher-order component reluctance of the rotor flux is the same. If other orders of harmonic magnetic fields are required, the position of the magnetic barrier can be adjusted accordingly.

[0057] A special application that utilizes the higher harmonics of magnetic flux and phase current to simultaneously reduce power loss and generate torque is the operation of a low-pole configuration synchronous motor with changing poles, where the magnetic flux generated by the rotor poles contains significant harmonic components. Using magnetic barriers to shape harmonic reluctance can also be used in wound-pole synchronous motors with significant harmonic magnetic fields. If the motor has only wound poles (or winding excitation poles), and the air gap magnetic field generated by the wound poles contains significant third harmonic components, then the magnetic barrier can be applied to the q-axis of the third harmonic magnetic field on the rotor, because the d-axis reluctance of the fundamental magnetic field of the wound poles is naturally lower than its q-axis reluctance. Figure 23 In just one example, magnetic barriers 2301 and 2302 are positioned in the pole shoe region to increase the q-axis magnetoresistance of the third harmonic magnetic field.

[0058] Please note that the magnetic barrier used for magnetoresistive adjustment can also be integrated with other functions or used for other purposes, such as noise reduction, vibration reduction, etc.

[0059] In the above discussion, the magnetic poles are located on the rotor inside the stator. However, the disclosed technology is also applicable to motors with rotors located outside the stator (such as external rotors or multi-rotor motors), as well as motors with rotors arranged in parallel with the stator (such as axial flux motors). Furthermore, this technology can also be applied to motors with magnetic poles built into the stator. Moreover, although the discussion focuses on electric motors, the disclosed technology is also applicable to generators or electric motors in generator mode.

[0060] The above discussion is based on synchronous motors. This is merely one example. The techniques discussed above can also be applied to other types of motors and generators. For example, in brushless DC motors, dynamic configuration can be used to generate torque at multiple selected harmonics to output high torque in certain operating modes and reduce one or more unwanted higher-order fluxes in other operating modes to reduce power losses and mechanical vibrations, thereby improving efficiency and / or torque ripple in certain operating modes while increasing power / torque density when needed. The desired harmonic injection in multi-harmonic control depends on the characteristics, size, shape, and location of the permanent magnets and can be obtained through various methods, including analysis, simulation, calculation, testing, and arbitrary combinations thereof.

[0061] The magnetic poles described in this disclosure can be arranged in different parts of a motor or generator. For example, fixed magnetic poles can be arranged on one rotor or stator of the motor, while reversible magnetic poles can be arranged on another rotor or stator of the motor. If the motor contains multiple rotors or stators, the arrangement of magnetic poles between different rotors or stators can be different. For example, when the motor adopts a dual-rotor topology, one rotor can contain both fixed and reversible magnetic poles, while the other rotor contains only fixed magnetic poles, or different proportions of fixed and reversible magnetic poles can be combined. Technical solutions in motors that utilize magnetic field harmonics in different ways to achieve changes in the number of poles or different operating modes through different magnetic pole arrangements are all within the protection scope of this disclosure.

[0062] Although embodiments of the invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

[0063] Furthermore, the scope of this application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, means, methods, and steps described in the specification. As will be readily understood by those skilled in the art from the disclosure of this invention, processes, machines, manufactures, compositions of matter, means, methods, or steps that are currently existing or will be developed in the future and perform substantially the same function or achieve substantially the same effect as the corresponding embodiments described herein can be used according to the present invention. Therefore, the appended claims are intended to include such processes, machines, manufactures, compositions of matter, means, methods, or steps within their scope.

Claims

1. A dynamic configuration device, comprising: The rotor is magnetically coupled to the stator through the air gap; A multiphase winding located within the stator and configured to generate a first magnetic field in the air gap; as well as A set of permanent magnet poles and a set of wound magnetic poles located within the rotor are used to generate a second magnetic field in the air gap, wherein: A wire-wound magnetic pole has an excitation winding around its pole body; A d-axis magnetic barrier is set inside or around the wire-wound magnetic pole so that the d-axis magnetic reluctance of the wire-wound magnetic pole is approximately equal to the d-axis magnetic reluctance of a permanent magnet pole.

2. The apparatus of claim 1, wherein: A wound magnetic pole is located on the side of a permanent magnet pole; The polarity of the wire-wound magnetic pole can be switched in an operating mode by changing the direction of the current in the excitation winding around its pole body. After switching, the wire-wound magnetic pole and the permanent magnet magnetic pole are essentially merged into one magnetic pole, thereby changing the number of poles of the second magnetic field. as well as The number of poles of the first magnetic field is dynamically adjusted according to the change in the number of poles of the second magnetic field.

3. The apparatus of claim 2, wherein: All excitation windings of multiple wire-wound magnetic poles are connected to the power supply leads, so that the polarity of these wire-wound magnetic poles can be changed synchronously.

4. The apparatus of claim 1, wherein: In one operating mode, the harmonic components of the second magnetic field are adjusted by regulating the current amplitude in a wire-wound magnetic pole excitation winding.

5. The apparatus of claim 1, further comprising: Its d-axis magnetic barrier integrates cooling functionality.

6. The apparatus of claim 1, wherein: The current configuration of the excitation winding is synchronized and smoothly changes with the phase winding current adjustment during pole switching, so that the mechanical torque generated by the rotor remains constant or follows a predetermined pattern during pole switching.

7. The apparatus of claim 1, wherein: In one operating mode, the q-axis reluctance of a wire wound around a magnetic pole is approximately the same as the reluctance of a permanent magnet pole.

8. The apparatus of claim 1, wherein: The d-axis magnetic barrier is integrated with an excitation winding cavity and filled with the conductor of the excitation winding.

9. The apparatus of claim 8, wherein: The excitation winding chamber is shaped to reduce leakage flux between adjacent magnetic poles.

10. The apparatus of claim 1, wherein: The d-axis magnetic barrier is divided into multiple parts.

11. An electrical system comprising: The motor has multiple phase windings in its stator, and the rotor is magnetically coupled to the stator through an air gap, wherein: The multiphase winding is configured to generate a first magnetic field in the air gap; and The rotor is equipped with a set of permanent magnet poles and a set of wound magnetic poles to generate a second magnetic field in the air gap, wherein: Each wire-wound magnetic pole has an excitation winding surrounding its pole body; and The d-axis magnetic barrier is set inside or around the wire-wound magnetic pole body, so that the d-axis magnetic reluctance of the wire-wound magnetic pole is approximately equal to the d-axis magnetic reluctance of a permanent magnet pole. Multiple power converters connected to the multiple phase windings and configured to control the current in the multiple phase windings; and An excitation current regulator is configured to control the current in the excitation winding.

12. The system of claim 11, wherein: During the pole-switching transition, the excitation current regulator changes the direction of the current in the excitation winding of a single-wire magnetic pole to change the magnetic field polarity of the wire-wire magnetic pole. Thereafter, the wire-wire magnetic pole and at least one adjacent permanent magnet magnetic pole substantially merge into one magnetic pole, resulting in a change in the number of poles of the second magnetic field. as well as In response to changes in the number of poles of the second magnetic field, the number of poles of the first magnetic field is dynamically adjusted by controlling the current in the multiphase winding.

13. The system of claim 12, wherein: The plurality of power converters include a multi-harmonic current regulator in the dq coordinate system; The multi-harmonic magnetic field orientation control mechanism is configured to control torque across multiple harmonic planes during the transition between poles; and The excitation current regulator is configured to synchronize with the first magnetic field pole switching, and smoothly change the excitation winding current so that the output torque of the motor during the pole switching transition remains constant or follows a preset curve.

14. The system of claim 11, wherein: The excitation current regulator changes the amplitude of the excitation winding current in an operating mode to adjust the harmonic components of the second magnetic field.

15. The system of claim 11, wherein: One of the wire-wound magnetic poles has its excitation winding embedded in an excitation winding cavity, and the shape of the cavity makes its q-axis magnetic reluctance approximately equal to that of one of the permanent magnet poles.

16. The system of claim 11, wherein: In one operating mode, the amplitude of the current in the excitation winding is reduced, thereby weakening the fundamental component of the second magnetic field in the air gap, thus achieving weak magnetic operation.

17. A motor control method, comprising: The stator and rotor are magnetically coupled through an air gap; The rotor is configured to have a set of permanent magnet poles and a set of wound poles, wherein each wound pole has an excitation winding around its pole body. A d-axis magnetic barrier is configured in the wire-wound magnetic pole body to increase its d-axis magnetic reluctance, so that the spatial distribution of the first magnetic field generated by the permanent magnet pole and the wire-wound magnetic pole in the air gap in a working mode is similar to the spatial distribution in the vicinity of the wire-wound magnetic pole. as well as Multiple phase windings are configured in the stator, and a second magnetic field is generated in the air gap when current flows through the phase windings. The spatial distribution of the second magnetic field near a permanent magnet pole is similar to the spatial distribution near a first-line winding pole in an operating mode.

18. The method of claim 17, further comprising: The polarity of the first magnetic field poles is changed by reversing the current direction of its excitation winding during a pole-changing transition, thereby synchronously changing the number of poles of the first magnetic field, and the number of poles of the second magnetic field is changed by controlling the current in the multiphase winding.

19. The method of claim 18, further comprising: The current of the phase winding and the current of the excitation winding are controlled so that the torque generated by the rotor remains constant or follows a preset pattern during the pole changing process.

20. The method of claim 17, further comprising: By configuring the excitation winding chamber or magnetic barrier of a single-pole magnetic field, its d-axis magnetic reluctance can be adjusted to be approximately equal to that of a permanent magnet pole.

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