CN116937919A - Systems, components, and methods for permanent magnet-less motors and their control - Google Patents

Abstract

The application relates to a system, components and methods for a permanent magnet-less motor and control thereof. Systems, components, and methods for driving a motor are disclosed, including: a motor, the motor comprising: a rotor; the stator comprises a plurality of stator phase coils and a plurality of electromagnets, and the electromagnets and the stator phase coils are mutually dispersed; wherein the motor is configured to generate a first plurality of motor signals. A controller coupled to the motor to receive the first plurality of motor signals is configured to: a first plurality of control signals is generated to drive the inverter and the DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

Description

Systems, components, and methods for permanent magnet-less motors and their control

Priority claim

The present application claims priority from U.S. provisional application No.63/327,158 filed on 4 months 2022, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to systems, components, and methods for permanent magnet-less motor design, construction, and control. Embodiments of the present disclosure are directed to inventive and non-conventional systems associated with traction applications for transportation and industrial applications.

Background

Permanent magnets ("PM") are widely used in traction motors to replace field windings (or "field windings") in salient pole rotors that generate a static magnetic field. Since PM is more compact than a wound field coil (or "field coil"), a higher power density is achieved by using PM and copper losses in the field coil are eliminated. However, PM motor technology has several drawbacks. One problem is that field weakening for high speed control cannot be performed without sacrificing efficiency and risking demagnetization. PM also produces a fixed unidirectional field that cannot operate to form a flux path. Furthermore, PM often has a serious limitation of availability to rare earth elements in a few countries, resulting in high costs and availability risks. In fault conditions, a motor using PM may generate uncontrolled open back emf that jeopardizes the power converter and safety (especially at high rotor speeds). Positioning the PM on the rotor also presents problems such as sticking problems in manufacturing and may limit the motor to lower allowable operating speeds. Emerging stator-PM machines rely on excessive PM to achieve high torque density, and torque increases are constrained by the saturation of the magnetic core, and further torque density increases by increasing the stator current are not feasible.

Accordingly, there is a need for improved systems, components, and methods for motor control. The present disclosure describes systems, components, and methods that overcome the disadvantages of rotor mounted PM by replacing the rotor mounted PM in a conventional motor topology with stator mounted electromagnets. By adopting the architecture, the dependence on key rare earth elements is eliminated; fine tuning of field weakening via reduced field excitation current results in wide constant power range performance; disabling inherent fault protection of field excitation by using a power electronic field drive converter to collapse back emf; and by using a simple laminated steel rotor without any permanent magnets, high speed rotor operation can be achieved, with up to four times higher power density, converting to weight and cost reductions compared to the state of the art.

The disclosed systems, components, and methods for permanent magnet-free motor control aim to overcome one or more of the problems set forth above and/or other problems of the prior art.

Disclosure of Invention

One aspect of the present disclosure may relate to a system for driving a motor, the system including: a motor, the motor comprising: a rotor; and a stator including a plurality of stator phase coils and a plurality of electromagnets. The plurality of electromagnets are interdispersed with the plurality of stator phase coils, wherein the motor is configured to generate a first plurality of motor signals. In one embodiment, a controller coupled to the motor to receive the first plurality of motor signals may be configured to: a first plurality of control signals is generated to drive the inverter and the DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

Another aspect of the present disclosure relates to a method for driving a motor, the method comprising: coupling a controller to a motor, the motor comprising: a rotor; and a stator including a plurality of stator phase coils and a plurality of electromagnets, the plurality of electromagnets being mutually dispersed with the plurality of stator phase coils. The method may include generating a first plurality of motor signals with the motor. The method may further include generating, with the controller, a first plurality of control signals to drive an inverter and a DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

Yet another aspect of the present disclosure relates to an n-phase motor, comprising: a rotor; and a stator including a plurality of stator phase coils and a plurality of electromagnets, the plurality of electromagnets being mutually dispersed with the plurality of stator phase coils. The plurality of electromagnets may be configured to generate a circumferential flux in a clockwise or counter-clockwise direction based on a DC excitation current, and the plurality of stator phase coils are configured to modulate a density of the circumferential flux.

Other systems, methods, and components are also discussed herein.

Drawings

Fig. 1A illustrates a cross-sectional view of an exemplary motor topology for magnet-less control consistent with some embodiments of the present disclosure.

Fig. 1B illustrates an alternative view of an exemplary motor topology for magnet-less control consistent with some embodiments of the present disclosure.

Fig. 2 illustrates circumferential flux associated with an exemplary magnet configuration consistent with some embodiments of the present disclosure.

Fig. 3 illustrates an exemplary magnet configuration associated with an electric machine including a single stator dual rotor configuration consistent with some embodiments of the present disclosure.

Fig. 4 illustrates an exemplary magnet configuration associated with an electric machine including a dual stator single rotor configuration consistent with some embodiments of the present disclosure.

Fig. 5 illustrates an exemplary magnet configuration associated with an electric machine including a dual stator single rotor configuration and both permanent magnets and electromagnets consistent with some embodiments of the present disclosure.

Fig. 6 is a system diagram of an exemplary motor control system consistent with some embodiments of the present disclosure.

Detailed Description

The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or like parts. Although a few illustrative embodiments have been described herein, modifications, adaptations, and other embodiments are possible. For example, substitutions, additions or modifications may be made to the components and steps illustrated in the drawings, and the illustrative methods described herein may be modified by substituting, reordering, removing, or adding steps to the disclosed methods. Therefore, the following detailed description is not limited to the disclosed embodiments and examples. Rather, the proper scope of the application is defined by the appended claims.

Known systems and methods for driving motors involve the use of permanent magnets on the rotor. Embodiments of the present disclosure relate to systems, components, and methods configured to drive a motor by: (1) Repositioning magnets from the rotor to the stator, (2) simplifying the rotor and stator structure using a modular core, and (2) replacing Permanent Magnets (PM) with electromagnets to partially or completely eliminate the use of permanent magnets. For ease of discussion, the following describes an example system for driving a motor, with the understanding that aspects of the example system are equally applicable to methods and components.

The disclosed embodiments may include an n-phase motor comprising: a rotor; and a stator, the stator comprising: the device comprises a plurality of stator phase coils and a plurality of electromagnets, wherein the plurality of electromagnets and the plurality of stator phase coils are mutually dispersed; wherein the plurality of electromagnets are configured to generate a circumferential flux in a clockwise or counter-clockwise direction based on a DC excitation current, and the plurality of stator phase coils are configured to modulate a density of the circumferential flux.

An n-phase motor may be a device that converts electric energy into mechanical motion by using a rotating magnetic field. The motor may be of the radial flux type, or of the axial flux type, or a hybrid combination of both. The motor of this topology may be driven by a combination of an inverter for phase current control and a DC-DC converter for field current control. Fig. 1A illustrates a cross-sectional view of an exemplary motor topology for magnet-less control consistent with some embodiments of the present disclosure. Fig. 1B illustrates an alternative view of an exemplary motor topology for magnet-less control consistent with some embodiments of the present disclosure. As shown in fig. 1A and 1B, one example of an n-phase motor 100 includes a device including three-phase coils, such as a phase a coil 101, a phase B coil 102, and a phase C coil 103. The motor may also include a plurality of electromagnets, such as electromagnet 104, interspersed with the plurality of stator phase coils 101, 102, 103 on the stator 105. Rotor 106 may also be devoid of magnets.

In some embodiments, the motor may include electromagnets disposed in a spaced relationship with the stator phase coils of the n-phase motor, as shown in fig. 1A and 1B. Fig. 2 illustrates circumferential flux associated with an exemplary magnet configuration consistent with some embodiments of the present disclosure. As shown in fig. 2, the DC excitation current of each electromagnet 201 may be selectively reversed by reversing the polarity of the respective field coil currents of the electromagnets 201 using a field driven power converter to provide a clockwise or counter-clockwise circumferential flux as desired.

In the configuration shown in fig. 2, the ac electromagnet is energized by modulating the field coil DC current in a manner that produces clockwise and counterclockwise fluxes. As the phase coil current increases, the phase coil current establishes a field that interacts with the electromagnet flux, and as a result the flux lines across the air gap increase and the air gap flux density increases. Thus, the air gap flux density can be modulated in amplitude and direction by closely adjusting the electromagnet excitation current via the DC-DC power converter and by adjusting the phase coil current via the inverter. The three-phase current generates a rotating magnetic field in the air gap, thereby generating motor torque, which rotates the rotor. Unlike other DC field excitation motor topologies that locate the field coils in the rotor, the topology of the presently disclosed embodiments with stator field coils does not require highly complex excitation current delivery mechanisms, such as brushes, slip rings, inductive wireless power transmitters, or capacitive wireless power transmitters.

In the cross-sectional view of the motor shown in fig. 1A, the cross-section of the DC field coil (electromagnet) 104 is rectangular. In other variations, the cross-section of the DC field coil may be other shapes. A specific variant with a trapezoidal cross section is shown in fig. 2, wherein the cross-sectional shape of the DC field coil (electromagnet) 201 is trapezoidal. In some embodiments, the motor may be a radial flux motor, as shown in fig. 1 and 2. In other embodiments, the motor may be an axial flux motor, as shown in fig. 3-5.

The variants shown in fig. 1A, 1B and 2 show that all permanent magnets in the motor stator are replaced by electromagnets or DC field coils. In other embodiments, hybrid approaches are possible in which some of the permanent magnets are replaced by electromagnets or DC field coils. In such an embodiment, permanent magnets are always present in the magnetic circuit to enable the motor to generate torque. In such embodiments, the DC field coils may be energized by a DC-DC power converter to generate the necessary additional electromagnetic torque when additional or enhanced output torque is desired.

In some embodiments, the motor configuration and operation may also be of the axial flux type. In the axial flux topology, several variants are possible, such as single stator and single rotor, single stator and double rotor, and double stator and double rotor. In some embodiments, similar to radial flux motors, hybrid versions may be implemented in which some of the permanent magnets are replaced with electromagnets (DC field windings), with the DC field coils selectively energized for time-limited boost torque generation.

Fig. 3 illustrates an exemplary magnet configuration associated with an electric machine including a single stator dual rotor configuration consistent with some embodiments of the present disclosure. As shown in fig. 3, the motor may include a single stator 301 and two rotors 302 and 303. In addition to the inter-dispersed electromagnets 307, the stator 301 may also include phase coils 304, 305 and 306. Fig. 4 illustrates an exemplary magnet configuration associated with an electric machine including a dual stator single rotor configuration consistent with some embodiments of the present disclosure. As shown in fig. 4, the motor may include two stators 401 and 402 and a single rotor 403. The first stator 401 may include phase coils 404, 405, and 406 in addition to the mutually dispersed electromagnets 407. In addition to the inter-dispersed electromagnets 411, the second stator 402 may also include phase coils 408, 409 and 410. Fig. 5 illustrates an exemplary magnet configuration associated with a motor including both permanent magnets and electromagnets consistent with some embodiments of the present disclosure. As shown in fig. 5, the motor may include two stators 501 and 502 and a single rotor 503. In addition to the inter-dispersed electromagnet 507, the first stator 501 may include phase coils 504, 505, and 506. In addition to the inter-dispersed permanent magnets 511, the second stator 502 may include phase coils 508, 509, and 510.

The disclosed embodiments may include a system for driving a motor, the system comprising: a motor, the motor comprising: a rotor; the stator comprises a plurality of stator phase coils and a plurality of electromagnets, and the electromagnets and the stator phase coils are mutually dispersed; wherein the motor is configured to generate a first plurality of motor signals; and a controller coupled to the motor to receive the first plurality of motor signals, the controller configured to: a first plurality of control signals is generated to drive the inverter and the DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

Fig. 6 is a system diagram of an exemplary motor control system consistent with some embodiments of the present disclosure. As shown in fig. 6, the system may include a motor 601 consistent with embodiments disclosed herein. For example, the motor 601 may include a radial flux type motor 100 as disclosed in fig. 1A and 1B. In other embodiments, the motor 601 may comprise an axial flux type motor as disclosed in any of fig. 3-5. The motor 601 may be any type of motor disclosed herein or may include any combination of the structures disclosed herein. The electric machine 601 may be used to power a vehicle 602. The motor 601 may generate a plurality of motor signals to a feedback and signal conditioning module 603 of the controller. The feedback and signal conditioning module 603 may process the plurality of motor signals to determine a plurality of values including motor speed, motor torque, phase current, and field current. The feedback and signal conditioning module 603 may be coupled to a plurality of control algorithm modules 604 configured to generate a plurality of control signals including speed control, torque control, stator current control, and field control. The control algorithm module 604 may generate a plurality of control signals to generate drive inverter switching functions 605 and DC-DC converter switching functions 606. The drive inverter 608 and DC-DC converter 607 may generate phase currents and electromagnet excitation currents to regulate the function of the motor 601.

The controller may include one or more processors and a storage medium coupled to the processors, on which one or more computer programs or software components may be stored. As used herein, a "processor" may include a processor core or a processing chip. For example, a programmable controller having multiple processors may include a single processing chip having multiple cores (e.g., 2, 4, 8, etc.), or may include multiple processing chips (e.g., multiple central processing units), where each processing chip includes one or more processors. Multiple processors may refer to any combination of chips and cores. The storage medium may store one or more executable programs to perform the methods described herein. In some embodiments, the controller may include a microcontroller or any other compact integrated circuit designed to manage specific operations in the embedded system. The microcontroller may be programmable. In other embodiments, the controller may comprise a Field Programmable Gate Array (FPGA) or any other semiconductor device based on a matrix of Configurable Logic Blocks (CLBs) connected via programmable interconnects. The FPGA may be reprogrammed after manufacture to accommodate the application or functional requirements corresponding to the functionality of the present disclosure.

As shown in fig. 6, in some embodiments, a separate DC-DC converter 606 for regulating the DC field current may be included in addition to the motor-driven inverter 605 providing motor phase current. The power electronics stack (PE stack) shown in fig. 6 may be constructed as a 2-stage output voltage stack or a multi-stage output voltage stack, depending on the availability of DC voltages and the blocking voltage ratings of the devices. Some example topologies for the level 2 and level 3 PE stacks are shown in fig. 6. In some embodiments, the stack may utilize a power semiconductor device, such as a MOSFET or IGBT.

In some embodiments, the controller may determine the phase current and the DC field current based on the speed and torque references and the measured speed and torque values. In PM machines, the electromagnetic torque produced is a function of the number of rotor poles, direct and quadrature inductances, stator current values, and permanent magnet flux. In such PM machines, the increase in commanded torque can only be achieved by increasing the magnitude of the stator phase current through the motor. However, in the embodiments disclosed herein, the electromagnetic torque generated may be a function of the number of rotor poles, direct and quadrature inductances, stator current values, and DC field coil currents, as shown in the following equations. The following equation provides an example of one implementation of a torque function. Other implementations may include additional variables or the removal of certain variables. Some other implementations may include other non-idealities or nonlinearities, or remove some non-idealities or nonlinearities.

Wherein T is _o Is to output electromagnetic torque, P _o Is the output power omega _m Is angular velocity, P is the number of poles, i _d ^e And i _q ^e Is the direct and quadrature currents obtained by abc-dq transformation, L _dd ^e And L _qq ^e Is the direct axis and quadrature axis inductance, lambda _dc Is the flux linkage caused by the current in the electromagnetic field winding.

In some embodiments, in addition to stator current as a variable, DC field coil current may also be used to regulate torque. The increase in electromagnetic torque demand can be achieved by adjusting the phase currents (using a multiphase inverter) and the DC field currents (using a field current DC-DC converter) in optimized proportions to achieve maximum operating efficiency. Positioning the DC field coils in the stator allows for high bandwidth control of the field flux, enabling fast and dynamic control of the electromagnetic torque of the motor. In other motor architectures, such as internal permanent magnet motors, replacing PM in the rotor with an electromagnet in the rotor requires a field transmission mechanism, such as brushes, slip rings, inductive wireless power transmitters, or capacitive wireless power transmitters. The control bandwidth available in these embodiments will be limited by the field transmission mechanism and therefore also the dynamic torque performance of the system.

When the motor enters a high-speed constant power region, field weakening can be used to minimize back emf voltage at the stator terminals. In embodiments of the present disclosure, this may be easily achieved by modulating the DC field coil current via a DC-DC power converter. PM machines rely solely on the injection of stator current, the phase difference of which from the back emf of the motor varies with operating speed. The embodiments disclosed herein may use modulation of the DC field coil current to weaken the field in addition to the stator current phase angle approach.

The disclosed embodiments may include a method for driving a motor, the method comprising: coupling a controller to a motor, the motor comprising: a rotor; the stator comprises a plurality of stator phase coils and a plurality of electromagnets, and the electromagnets and the stator phase coils are mutually dispersed; generating a first plurality of motor signals with a motor; and generating, with a controller, a first plurality of control signals to the drive inverter and the DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

While the disclosure has been shown and described with reference to particular embodiments thereof, it will be understood that the disclosure may be practiced in other environments without modification. The foregoing description has been presented for purposes of illustration. It is not intended to be exhaustive and is not limited to the precise form or embodiment disclosed. Other embodiments may include radial flux machines with dual (inner and outer) rotors, axial flux machines with one stator and one rotor, stacked axial flux machines with multiple stators and multiple rotors coupled together. Modifications and adaptations may become apparent to those skilled in the art from a consideration of the specification and practice of the disclosed embodiments.

Computer programs based on written description and disclosed methods are within the skill of an experienced developer. The various programs or program modules may be created using any technique known to those skilled in the art or may be designed in conjunction with existing software. For example, program portions or program modules may be designed in or with Net Framework, net Compact Framework (and related languages such as Visual Basic, C, etc.), java, C++, objective-C, HTML, HTML/AJAX combinations, XML, or HTML with Java applets. The program portions or program modules may also be designed or utilized in an integrated design environment as specified or provided by a commercially available microcontroller, processor, or field programmable gate array manufacturer.

Moreover, although illustrative embodiments have been described herein, those of ordinary skill in the art will, based on the present disclosure, appreciate the scope of any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., across aspects across various embodiments), adaptations and/or alterations. Limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the present specification or during prosecution of the application. These examples are to be construed as non-exclusive. In addition, the steps of the disclosed methods may be modified in any manner, including by reordering steps and/or inserting or deleting steps. It is intended, therefore, that the specification and examples be considered as exemplary only, with a true scope and spirit being indicated by the following claims and their full scope of equivalents.

Claims (20)

1. A system for driving a motor, the system comprising:

a motor, the motor comprising:

a rotor; and

the stator comprises a plurality of stator phase coils and a plurality of electromagnets, wherein the electromagnets and the stator phase coils are mutually dispersed;

wherein the motor is configured to generate a first plurality of motor signals; and

a controller coupled to the motor to receive the first plurality of motor signals, the controller configured to:

a first plurality of control signals is generated to drive the inverter and the DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

2. The system of claim 1, wherein the first plurality of motor signals comprises at least one of motor speed, motor torque, phase current, and field current.

3. The system of claim 1, wherein the first plurality of control signals includes at least one of speed control, torque control, stator current control, and field control.

4. The system of claim 1, wherein the system further comprises at least one field driven power converter to generate the at least one excitation current.

5. The system of claim 4, wherein the at least one field drive power converter is configured to generate the at least one excitation current by reversing current polarity of the plurality of stator phase coils.

6. The system of claim 1, wherein the at least one excitation current is configured to produce a clockwise flux.

7. The system of claim 1, wherein the at least one excitation current is configured to produce a counter-clockwise flux.

8. The system of claim 1, wherein the motor is free of permanent magnets.

9. The system of claim 1, wherein the motor further comprises at least one permanent magnet.

10. The system of claim 1, wherein the motor is an n-phase motor.

11. The system of claim 1, wherein the motor structure is of an axial flux type.

12. The system of claim 1, wherein the motor structure is of a radial flux type.

13. The system of claim 1, wherein the motor structure is a combination of an axial flux type and a radial flux type.

14. The system of claim 1, wherein the system further comprises a plurality of power electronics stacks configured to provide power to the motor.

15. A method for driving a motor, the method comprising:

coupling a controller to a motor, the motor comprising:

a rotor; and

the stator comprises a plurality of stator phase coils and a plurality of electromagnets, wherein the electromagnets and the stator phase coils are mutually dispersed;

generating a first plurality of motor signals with the motor; and

generating, with the controller, a first plurality of control signals to the drive inverter and the DC-DC converter to affect at least one phase current delivered to at least one of the plurality of stator phase coils and at least one excitation current delivered to at least one of the plurality of electromagnets.

16. The method of claim 15, wherein the first plurality of motor signals includes at least one of motor speed, motor torque, phase current, and field current.

17. The method of claim 15, wherein the first plurality of control signals includes at least one of speed control, torque control, stator current control, and field control.

18. The method of claim 15, wherein the method further comprises generating a clockwise flux using the at least one excitation current.

19. The method of claim 15, wherein the method further comprises generating a counter-clockwise flux using the at least one excitation current.

20. An n-phase motor comprising:

a rotor; and

a stator including a plurality of stator phase coils and a plurality of electromagnets, the plurality of electromagnets being mutually dispersed with the plurality of stator phase coils,

wherein the plurality of electromagnets are configured to generate a circumferential flux in a clockwise or counter-clockwise direction based on a DC excitation current, and the plurality of stator phase coils are configured to modulate a density of the circumferential flux.