Flexible control of six-phase motors

Abstract

A method for controlling a multiphase motor, the method comprising the steps of: implementing a first control method for controlling the operation of a six-phase motor, the six-phase motor being configured as a combination of two three-phase motors. The method further comprises the step of: determining whether a fault exists in the six-phase motor. The method further comprises the step of: in response to determining that a fault exists in the six-phase motor, implementing a different second control method for controlling the operation of the six-phase motor.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 890,282, filed August 22, 2019, entitled “FLEXIBLE CONTROL FOR A SIX-PHASE MACHINE,” the entire disclosure of which is expressly incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to multiphase motors, and more particularly to the application of different control strategies to enable a six-phase motor to operate in both healthy and faulty conditions. Background Technology

[0004] Multiphase motors are used in a variety of applications, including electric vehicles. For example, the drive system of an electric vehicle typically includes an AC motor driven by a direct current (DC) power source (e.g., a main battery). The AC motor is connected to the DC power source via a power inverter that performs a switching function to convert DC power to AC power. An example of a multiphase motor is a six-phase AC motor. The performance of a six-phase AC motor can vary significantly between healthy and faulty conditions. Therefore, it remains necessary to develop optimal control strategies with fault-handling capabilities for operating six-phase AC motors. Summary of the Invention

[0005] According to one embodiment, this disclosure provides a method for operating a six-phase motor configured as a combination of two three-phase motors by applying different control strategies using a controller. The method includes the step of implementing a first control method for controlling the operation of the six-phase motor. The method further includes the step of determining whether a fault exists in the six-phase motor. In response to determining that a fault exists in the six-phase motor, the method includes the step of implementing different second control methods for controlling the operation of the six-phase motor.

[0006] On the other hand, the first control method is a six-phase control technique that controls all six phases of the six-phase motor, and the second control method is a three-phase control technique that controls each of the two three-phase motors individually.

[0007] On the other hand, the method includes the following steps: determining which of the two three-phase motors is experiencing a fault. To this end, the three-phase motor experiencing the fault is disabled, and a second control method is applied to the remaining three-phase motors that are not experiencing the fault. Since the two three-phase motors operate in a phase-shifted manner with their respective windings shifted by phase values, implementing the second control method requires referencing new phase values ​​so that the remaining three-phase motors that are not experiencing the fault operate in the same phase-shifted manner as before the fault occurred.

[0008] According to another embodiment, this disclosure provides a controller including a processor and a memory. The memory includes instructions that, when executed by the processor, cause the controller to implement a first control method for controlling the operation of a six-phase motor. The six-phase motor is configured as a combination of two three-phase motors. The processor also causes the controller to: determine whether a fault exists in the six-phase motor. In response to determining that a fault exists in the six-phase motor, the processor causes the controller to implement different second control methods for controlling the operation of the six-phase motor.

[0009] On the other hand, the first control method is a six-phase control technique that controls all six phases of the six-phase motor, and the second control method is a three-phase control technique that controls each of the two three-phase motors individually.

[0010] On the other hand, the processor enables the controller to determine which of the two three-phase motors is experiencing a fault. To this end, the three-phase motor experiencing the fault is disabled, and a second control method is applied to the remaining three-phase motors that are not experiencing a fault. Since the two three-phase motors operate in a phase-shifted manner with their respective windings shifted by phase values, implementing the second control method requires referencing new phase values ​​so that the remaining three-phase motors that are not experiencing a fault operate in the same phase-shifted manner as before the fault occurred.

[0011] According to another embodiment, this disclosure provides a system comprising: a six-phase motor and a controller coupled to the six-phase motor. The six-phase motor is configured as a combination of two three-phase motors. The controller is configured to implement a first control method for controlling the operation of the six-phase motor. The controller is also configured to determine whether a fault exists in the six-phase motor. In response to determining that a fault exists in the six-phase motor, the controller is configured to implement different second control methods for controlling the operation of the six-phase motor.

[0012] On the other hand, the first control method is a six-phase control technique that controls all six phases of the six-phase motor, and the second control method is a three-phase control technique that controls each of the two three-phase motors individually.

[0013] On the other hand, the controller is also configured to determine which of the two three-phase motors is experiencing a fault. To this end, the three-phase motor experiencing the fault is disabled, and a second control method is applied to the remaining three-phase motor that is not experiencing a fault. Since the two three-phase motors operate in a phase-shifted manner with their respective windings shifted by phase values, implementing the second control method requires referencing new phase values ​​so that the remaining three-phase motor that is not experiencing a fault operates in the same phase-shifted manner as before the fault occurred. Attached Figure Description

[0014] The above and other features and advantages of this disclosure, as well as the ways in which they are obtained, will become clearer and the invention itself will be better understood by referring to the following description of embodiments of the invention in conjunction with the accompanying drawings, in which:

[0015] Figure 1 This is a block diagram illustrating a six-phase motor system;

[0016] Figures 2 to 3 This is an example used to make Figure 1 A graphical representation of the control method for operating a six-phase motor system; and

[0017] Figure 4 This is an example used to make Figure 1 A flowchart of the operation method of a six-phase motor system.

[0018] Throughout these views, corresponding labels indicate the corresponding parts. The examples described herein illustrate exemplary embodiments of this disclosure, and these examples should not be construed as limiting the scope of this disclosure in any way. Detailed Implementation

[0019] For the purpose of promoting understanding of the principles of this disclosure, embodiments illustrated in the accompanying drawings are now described. The exemplary embodiments disclosed herein are not intended to be exclusive or to limit this disclosure to the precise forms disclosed in the following detailed description. Rather, these exemplary embodiments have been chosen and described so that others skilled in the art can utilize their teachings.

[0020] The terms “connected,” “connected,” and variations thereof are used to include both arrangements in which two or more components are in direct physical contact with each other and arrangements in which two or more components are not in direct contact with each other (e.g., these components are “connected” via at least a third component) but still cooperate or interact with each other.

[0021] Throughout this disclosure and in the claims, numerical terms such as first and second are used to refer to various components or features. This use is not intended to indicate an order of these components or features. Rather, numerical terms are used to help the reader identify the referenced components or features and should not be interpreted narrowly as providing a specific order of components or features.

[0022] Those skilled in the art will recognize that the provided implementations can be implemented in hardware, software, firmware, and / or a combination thereof. The programming code according to the implementations can be implemented in any feasible programming language, such as C, C++, HTML, XTML, JAVA, or any other feasible high-level programming language, or a combination of high-level and low-level programming languages.

[0023] Now refer to Figure 1 A block diagram of a six-phase motor system 100 is shown, which includes a six-phase AC motor 102, a six-phase inverter 104, a current regulator 106, and a controller 108. As used herein, the term "AC motor" refers to an AC power supply device that converts electrical energy into mechanical energy or mechanical energy into electrical energy. AC motors can be classified into synchronous AC motors and asynchronous AC motors. Synchronous AC motors can include permanent magnet motors and reluctance motors. In one embodiment, the six-phase AC motor 102 is a six-phase asymmetric internal permanent magnet synchronous AC motor used to provide torque in an electric vehicle. However, it should be appreciated that, in the context of other applications, the disclosed embodiments may relate to other types of multiphase motors.

[0024] The six-phase AC motor 102 has six windings 102A to 102F, each winding being associated with a corresponding phase A to F of the six-phase AC motor 102. Windings 102A to 102C are connected together at a first neutral connection 110, while windings 102D to 102F are connected together at a second neutral connection 112. Electrical isolation between the first neutral connection 110 and the second neutral connection 112 makes the six-phase AC motor 102 inherently asymmetrical. With this configuration, the six-phase AC motor 102 is mounted as if it were two separate three-phase motors. That is, windings 102A to 102C comprise the first three-phase motor, while windings 102D to 102F comprise the second three-phase motor. The two sets of windings are shifted relative to each other by phase value (e.g., spatially) to improve torque performance.

[0025] Windings 102A to 102F represent the stator of the six-phase AC motor 102. For ease of illustration, the stator and other components (e.g., rotor, shaft, etc.) of the six-phase AC motor 102 are not shown. Typically, the rotor is mounted to the shaft, and the rotor is separated from the stator by an air gap. When used as a motor, the stator uses electrical energy to rotate the rotor, which in turn rotates the shaft to provide mechanical energy. On the other hand, when used as a generator, external mechanical force rotates the shaft, which in turn rotates the rotor, thereby generating electrical energy in the stator.

[0026] The six-phase inverter 104 particularly includes switching devices (e.g., transistors, diodes, etc.) to properly switch the DC voltage and provide excitation to the windings 102A to 102F of the six-phase AC motor 102, as known to those skilled in the art. Specifically, the six-phase inverter 104 provides stator current (Ist) to the respective windings 102A to 102F. A to I F )114A to 114F. In one example, the six-phase inverter 104 is a pulse width modulation inverter.

[0027] The current regulator 106 includes current control modules 106A and 106B. Current control module 106A receives a reference current (I0) from windings 102A to 102C. d1q1ref )116, and the current control module 106B receives the reference current (I) from windings 102D to 102F. d2q2ref Reference currents 116 and 118 are in a synchronous (or rotating) reference frame and therefore include a direct-axis (d-axis) component, an orthogonal-axis (q-axis) component, and a zero-sequence component. Reference currents 116 and 118 are command signals that will cause the six-phase AC motor 102 to generate the desired torque at the desired rotational speed. The use of reference current signals is known to those skilled in the art.

[0028] Current control modules 106A and 106B also receive feedback current (I) from windings 102A to 102C and 102D to 102F, respectively. d1q1m )120 and (I d2q2m )122. The feedback currents 120 and 122 are the measured stator currents 114A to 114F that have been converted into the d-axis component, q-axis component, and zero-sequence component in the synchronous reference frame. This conversion process is known to those skilled in the art.

[0029] By using reference currents 116 and 118 and feedback currents 120 and 122, current control modules 106A and 106B generate reference voltages for the windings using a synchronous reference system. That is, the reference voltages (V) for windings 102A to 102C. d1q1 )124, and the reference voltage (V) for windings 102D to 102F. d2q2126. This current-to-voltage conversion process can be performed using any suitable device, such as a proportional-integral (PI) controller. Although Figure 1 While current control modules 106A and 106B are shown as separate modules, in other embodiments, they may be implemented as a single unit within control regulator 106. In some implementations, control regulator 106 may be part of controller 108.

[0030] The controller 108 receives reference voltages 124, 126 (e.g., from the current regulator 106), rotor / shaft position (θr) 128 (e.g., based on measured or estimated information from the six-phase AC motor 102), and DC voltage input (V). DC )130 (e.g., from a battery). Using these inputs, controller 108 generates a control voltage (V) with a stationary reference frame. A To V F The control voltage is then sent from windings 132A to 132F to control the switching operation of the six-phase inverter 104, thereby controlling the output supplied to windings 102A to 102F (e.g., 114A to 114F). The process of synchronous to static switching is known to those skilled in the art.

[0031] The controller 108 includes a fault detection unit or module 134 that receives information associated with the six-phase inverter 104 and / or the six-phase AC motor 102 to determine faults. For example, the fault detection module 134 may receive information from sensors (e.g., current sensors) indicating various characteristics (e.g., amplitude measurements, root mean square measurements, etc.) of the current supplied by the six-phase inverter 104 to windings 102A through 102F. As another example, the fault detection module 134 may receive information from sensors indicating the condition of windings 102A through 102F. The fault detection module 134 then processes the received information and determines whether a fault or failure condition has occurred in one or more phases (e.g., phases A through F) of the six-phase AC motor 102. Although Figure 1 The fault detection module 134 is shown as part of the controller 108, but in other embodiments, the fault detection module 134 may be a separate unit communicatively connected to the controller 108.

[0032] In one example, when an open circuit is detected between a winding in a six-phase AC motor 102 and the terminals connecting that winding to a six-phase inverter 104, the fault detection module 134 determines a fault in a phase of the six-phase AC motor 102. The open circuit may occur due to factors such as a physical disconnection (e.g., a broken wire) and / or winding damage. In another example, the fault detection module 134 determines a fault in a phase when one or more switches associated with a phase of the six-phase inverter 104 are turned off or are operating in a faulty manner. This may be due to factors such as failure or malfunction in electronic circuitry. Once the fault detection module 134 determines a fault, it generates information indicating the fault. This information may indicate the fault condition causing the fault and / or which(s) were currently experiencing the fault. In some implementations, the fault detection module 134 provides a fault signal to an output unit (e.g., a display, indicator light, speaker, etc.) to indicate the detected fault to an observer (e.g., the operator of an electric vehicle).

[0033] The controller 108 also includes a non-transitory memory 136 with instructions that, in response to execution by the processor 138, cause the processor 138 to perform the functions of the controller 108 and / or the fault detection module 134 as described above. The non-transitory memory 136, the processor 138, and the controller 108 are not particularly limited and may, for example, be physically separate.

[0034] In some implementations, controller 108 may form part of a processing subsystem that includes one or more computing devices having memory, processing, and communication hardware. Controller 108 may be a single device or a distributed device, and the functions of controller 108 may be executed by hardware and / or as computer instructions on a non-transitory computer-readable storage medium (such as non-transitory memory).

[0035] In some implementations, controller 108 includes one or more interpreters, determiners, evaluators, regulators, and / or processors that functionally perform the operations of controller 108. The interpreters, determiners, evaluators, regulators, and processors may implement computer instructions in hardware and / or as non-transitory computer-readable storage media, and may be distributed across various hardware or computer-based components.

[0036] Figure 1Configuring the six-phase AC motor 102 as two three-phase motors has some inherent advantages. For example, under normal or healthy conditions, the two three-phase motors can operate together as a whole. However, when one of the three-phase motors fails, the other three-phase motor can still operate. Since the performance of the six-phase AC motor 102 may differ between healthy and faulty conditions, the controller 108 implements different control strategies or methods to operate the six-phase AC motor 102 for various conditions.

[0037] Under healthy conditions, controller 108 implements a first control method optimized for controlling all six phases of the six-phase AC motor 102. In one example, all phases of the six-phase AC motor 102 are projected to determine the d-axis (flux) and q-axis (torque) components for use under vector control. Figure 2 A graph 200 illustrating the implementation of the first control method is shown, in which flux / torque transformation is performed so that flux and torque are controlled using only a pair of dq components 202, 204.

[0038] The first control method has several advantages. First, it aligns the fundamental d-axis components of the current / voltage in all phases. Second, it uses only a single synchronous or rotating reference frame to carry all the energy. Third, there is no mutual coupling between the fundamental and harmonic components of the current / voltage, resulting in lower current and torque ripple. Fourth, additional harmonic components (e.g., third harmonic d-axis current, third harmonic q-axis component, etc.) can be used for more advanced torque control. In some implementations, the first control method inherits harmonic control techniques and basic control techniques for advanced torque ripple minimization.

[0039] In operating the six-phase AC motor 102 as two three-phase motors, the corresponding windings of each three-phase motor (e.g., 102A to 102C and 102D to 102F) are phase-shifted by a certain phase value to obtain better torque performance. In one example, windings 102A to 102C and 102D to 102F are shifted by 30 degrees. To compensate for the phase shift, the controller 108 generates a control voltage (V0) for windings 102A to 102C at 0 degrees (or -15 degrees) using a mid-reference. A To V C )132A to 132C. Similarly, controller 108 generates control voltages (V) for windings 102D to 102F at 30 degrees (or 15 degrees) using an intermediate reference. D To V F )132D to 132F.

[0040] In the event of a fault (i.e., when one of the three-phase motors becomes unusable due to a fault), the first control method is no longer suitable. In this case, the controller 108 implements a second control method that individually controls each of the two three-phase motors. Figure 3 A diagram 300 illustrating an implementation of the second control method is shown, in which flux / torque transformation is performed to individually control the flux and torque of each of the two three-phase motors using two pairs of dq components 302 to 304 and 306 to 308. In the second control method, each component of 302 to 308 is controlled individually. This allows for individual three-phase fault-tolerant control. In some embodiments, the second control method can be used to operate the six-phase AC motor 102. For example, when software problems prevent the deployment of the first control method, the controller 108 can apply the second control method to operate the six-phase AC motor 102 as a partially three-phase motor.

[0041] Now refer to Figure 4 A method 400 for controlling a six-phase motor (e.g., 102) is shown. Method 400 can be executed by a controller (e.g., 108). At block 402, the controller implements a first control method for controlling the operation of the six-phase motor, which is configured as a combination of two three-phase motors. (Refer to...) Figure 1 Windings 102A to 102C can be associated with one of the three-phase motors, while windings 102D to 102F can be associated with the other three-phase motor. In one example, the first control method is a six-phase control technique that controls all six phases of a six-phase motor.

[0042] At box 404, the controller determines whether a fault exists in the six-phase motor. The controller includes a fault detection module (e.g., 134) or can communicate with such a fault detection module to determine the fault condition causing the fault (e.g., an open-circuit fault condition). The controller can generate a signal indicating the fault condition. In one example, determining the fault requires the controller to determine which of the two three-phase motors is experiencing a fault.

[0043] At block 406, in response to determining that a fault exists in the six-phase motor, the controller implements a different second control method for controlling the operation of the six-phase motor. In one example, the second control method is a three-phase control technique that controls each of the two three-phase motors individually. When the second control method is implemented, the controller disables the three-phase motor experiencing the fault and applies the second control method to the remaining three-phase motors that are not experiencing the fault.

[0044] The two three-phase motors are operated with a phase shift by shifting the corresponding windings (e.g., 102A to 102C and 102D to 102F) of the two three-phase motors. Thus, when the second control method is implemented, the controller references the new phase values, ensuring that the remaining three-phase motor, which did not experience a fault, continues to operate with the same phase shift as before the fault occurred.

[0045] As described herein, controller 108 provides a flexible control technique for operating a six-phase AC motor 102 under both healthy and faulty conditions. When the six-phase AC motor 102 is healthy, controller 108 implements a first control method to optimize performance from all six phases. When the six-phase AC motor 102 becomes faulty, controller 108 implements a second control method to achieve individual three-phase control. In this way, the flexible control technique maximizes drive performance while achieving fault tolerance. This enables the six-phase AC motor 102 to be used more reliably in a variety of applications such as electric vehicles and the aerospace industry.

[0046] While the invention has been described with exemplary design, further modifications are possible within the spirit and scope of this disclosure. Therefore, this application is intended to cover any variations, uses, and alterations of the invention utilizing its general principles. Furthermore, this application is intended to cover deviations from this disclosure that fall within the known or customary practice of the field to which this invention pertains and are limited by the appended claims.

[0047] Furthermore, the connecting lines shown in the various figures included herein are intended to represent exemplary functional relationships and / or physical connections between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in a practical system. However, any element that provides a benefit, advantage, solution to a problem, or from which any benefit, advantage, or solution may arise or become more significant is not considered a critical, essential, or fundamental feature or element. Therefore, the scope is not limited by anything other than the appended claims, wherein, unless expressly stated otherwise, reference to an element in the singular does not mean "one and only one," but rather "one or more."

[0048] Furthermore, when phrases such as "at least one of A, B, or C" are used in the claims, it is intended to be interpreted as meaning that in an embodiment A may be present alone, in an embodiment B may be present alone, in an embodiment C may be present alone, or in a single embodiment any combination of elements A, B, or C may be present; for example, A and B, A and C, B and C, or A and B and C.

[0049] This document provides systems, methods, and apparatus. In the detailed description herein, references to "one embodiment," "an embodiment," "an example embodiment," etc., indicate that the described embodiment may include a particular feature, structure, or characteristic, but each embodiment may not necessarily include that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is understood by those skilled in the art to be capable of implementing such a feature, structure, or characteristic having the benefits of this disclosure in conjunction with other embodiments, whether explicitly described or not. After reading this description, those skilled in the art will understand how this disclosure can be implemented in alternative embodiments.

[0050] Furthermore, regardless of whether an element, component, or method step is expressly stated in the claims, the elements, components, or method steps in this disclosure are not intended to be exclusive to the public. As used herein, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Claims

1. A method for controlling a six-phase motor, wherein the six-phase motor is configured as a combination of two three-phase motors, the method comprising the following steps: A first control method is implemented by a controller to control all six phases of the six-phase motor together; The controller determines whether a fault exists in the six-phase motor; In response to the determination of a fault in the six-phase motor, the controller implements a second control method for individually controlling the corresponding three phases of each of the two three-phase motors. The step of determining whether a fault exists includes: determining which of the two three-phase motors is experiencing a fault. The steps for implementing the second control method include: disabling one of the two three-phase motors that is experiencing a fault, and applying the second control method to the remaining three-phase motors that are not experiencing a fault. The method further includes the following step: operating the two three-phase motors under phase shift conditions where the windings of the two three-phase motors are shifted by phase value. The steps for implementing the second control method include: referencing a new phase value, causing the remaining three-phase motor of the two three-phase motors to operate under the same phase shift conditions as before the fault occurred.

2. The method according to claim 1, wherein, The first control method utilizes a first pair of currents having d-axis and q-axis components, and a second pair of currents having harmonic components.

3. The method according to claim 2, wherein, The second control method utilizes the first pair of currents having d-axis and q-axis components.

4. A controller for controlling a six-phase motor, the six-phase motor being configured as a combination of two three-phase motors, the controller comprising: processor; as well as The memory includes instructions that, when executed by the processor, cause the controller to: A first control method is implemented for controlling all six phases of the six-phase motor together. Determine if there is a fault in the six-phase motor; In response to determining that a fault exists in the six-phase motor, a second control method is implemented for individually controlling different three phases of each of the two three-phase motors. Specifically, the instruction executed by the processor that causes the controller to determine whether a fault exists also causes the controller to determine which of the two three-phase motors is experiencing a fault. Specifically, the instruction executed by the processor to cause the controller to implement the second control method also causes the controller to disable one of the two three-phase motors that is experiencing a fault, and to apply the second control method to the remaining three-phase motor that is not experiencing a fault. When executed by the processor, the instruction also causes the controller to operate the two three-phase motors under phase shift conditions where the windings of the two three-phase motors are shifted by a phase value. The instruction that causes the controller to implement the second control method when executed by the processor also causes the controller to reference a new phase value, so that the remaining three-phase motor of the two three-phase motors operates under the same phase shift conditions as before the fault occurred.

5. The controller according to claim 4, wherein, The first control method utilizes a first pair of currents having d-axis and q-axis components, and a second pair of currents having harmonic components.

6. The controller according to claim 5, wherein, The second control method utilizes the first pair of currents having d-axis and q-axis components.

7. A system comprising: A six-phase motor, wherein the six-phase motor is configured as a combination of two three-phase motors; as well as A controller, connected to the six-phase motor, is configured to: A first control method is implemented for controlling all six phases of the six-phase motor together. Determine if there is a fault in the six-phase motor; as well as In response to determining that a fault exists in the six-phase motor, a second control method is implemented for individually controlling different three phases of each of the two three-phase motors. The controller is further configured to determine which of the two three-phase motors is experiencing a fault. The controller is further configured to disable one of the two three-phase motors that is experiencing a fault, and to apply the second control method to the remaining three-phase motor that is not experiencing a fault. The controller is configured to operate the two three-phase motors under phase shift conditions, where the windings of the two three-phase motors are shifted by a phase value. The controller is also configured to reference the new phase value so that the remaining three-phase motor of the two three-phase motors operates under the same phase shift conditions as before the fault occurred.

8. The system according to claim 7, wherein, The first control method utilizes a first pair of currents having d-axis and q-axis components and a second pair of currents having harmonic components, and the second control method utilizes the first pair of currents having d-axis and q-axis components.

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