A fault-tolerant control method and device for a multiphase motor

Abstract

This invention provides a fault-tolerant control method and apparatus for a multiphase motor, used in a drive circuit composed of the multiphase motor and a corresponding multiphase inverter bridge. The multiphase inverter bridge experiences a short-circuit or open-circuit fault, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all on the same half of the voltage vector space. The fault-tolerant control method includes: determining an available voltage vector range in the voltage vector space based on the controllable voltage vectors; determining a target voltage vector based on the current vehicle torque command; and determining an equivalent voltage vector of the target voltage vector within the available voltage vector range based on the relative positional relationship between the rotor flux direction, the target voltage vector, and the available voltage vector range, to control the multiphase motor.

Description

Technical Field

[0001] This invention relates to the field of inverter control, and more particularly to a fault-tolerant control method and apparatus for a multiphase motor. Background Technology

[0002] With the increasing market penetration of electric vehicles, various control technologies related to electric vehicles are also developing rapidly. Among them, the fault-tolerant control of inverters is a very important function in the field of electric vehicle control, and many existing technical solutions revolve around fault-tolerant control.

[0003] The electric drive system of an electric vehicle typically includes a matched multiphase inverter bridge and a multiphase motor. Fault-tolerant control of the inverter or multiphase motor refers to the ability of the inverter in the electric drive system to continue driving the motor and thus propel the electric vehicle even after one component of the inverter fails. Current technology for fault-tolerant control of multiphase motors generally achieves this by modifying the hardware topology. However, hardware modifications often increase system costs, hindering widespread adoption.

[0004] In order to overcome the above-mentioned defects in the existing technology, there is an urgent need in the field for a fault-tolerant control method and device for multiphase motors, which can realize the fault-tolerant control of multiphase motors without adding extra components or changing the hardware structure, and can effectively improve the reliability of electric vehicle electric drive system while saving costs. Summary of the Invention

[0005] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0006] To overcome the aforementioned deficiencies in the prior art, this invention provides a fault-tolerant control method for a multiphase motor, used in a drive circuit composed of the multiphase motor and a corresponding multiphase inverter bridge. The multiphase inverter bridge experiences a short-circuit or open-circuit fault, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all located on the same half of the voltage vector space. The fault-tolerant control method includes: determining an available voltage vector range in the voltage vector space based on the controllable voltage vector; determining a target voltage vector based on the current vehicle torque command; and determining an equivalent voltage vector of the target voltage vector within the available voltage vector range based on the relative positional relationship between the rotor flux direction, the target voltage vector, and the available voltage vector range, to control the multiphase motor.

[0007] In one embodiment, preferably, determining the equivalent voltage vector of the target voltage vector within the available voltage vector range based on the relative positional relationship of the rotor flux direction, the target voltage vector, and the available voltage vector range to control the multiphase motor includes: setting a d-axis and a q-axis in the voltage vector space, wherein the d-axis is the rotor flux direction, and the q-axis leads the d-axis by 90° along the motor rotation direction; as the multiphase motor rotates, dividing the voltage vector space into multiple working regions based on the relative positional relationship of the target voltage vector, the d-axis, the q-axis, and the available voltage vector range; and determining the equivalent voltage vector of the target voltage vector within each working region based on a preset strategy to control the multiphase motor.

[0008] In one embodiment, optionally, the multiphase motor is a three-phase motor. A short-circuit or open-circuit fault occurs in one switch of the multiphase inverter bridge. The target voltage vector is located in the second quadrant of the coordinate system formed by the d-axis and the q-axis. As the three-phase motor rotates counterclockwise, the target voltage vector, the d-axis, and the q-axis also rotate in the voltage vector space along the motor's rotation direction. Based on the relative positional relationship of the target voltage vector, the d-axis, the q-axis, and the available voltage vector range, the voltage vector space is divided into five working regions. The first working region begins in the counterclockwise direction of motor rotation, responding to the d-axis coinciding with the reverse extension of the starting vector of the available voltage vector range; in response to the target... When the voltage vector coincides with the starting vector of the available voltage vector range, the first working region ends and the second working region begins, during which the multiphase motor operates normally; in response to the target voltage vector coinciding with the ending vector of the available voltage vector range, the second working region ends and the third working region begins; in response to the q-axis coinciding with the ending vector of the available voltage vector range, the third working region ends and the fourth working region begins; in response to the q-axis coinciding with the reverse extension of the starting vector of the available voltage vector range, the fourth working region ends and the fifth working region begins; and in response to the d-axis coinciding again with the reverse extension of the starting vector of the available voltage vector range, the fifth region ends.

[0009] In one embodiment, preferably, in the first working region, determining the equivalent voltage vector of the target voltage vector based on a preset strategy to control the multiphase motor includes: selecting the equivalent voltage vector that produces the same torque as the target voltage vector between the reverse extension line of the d-axis and the termination vector of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage such that the q-axis current is positive and the d-axis current is negative; or selecting the equivalent voltage vector that produces the same torque as the target voltage vector between the reverse extension line of the d-axis and the starting vector of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage such that the q-axis current is positive and the d-axis current is negative.

[0010] In one embodiment, preferably, in the third working region, the step of determining the equivalent voltage vector of the target voltage vector based on a preset strategy to control the multiphase motor further includes: selecting the equivalent voltage vector that produces the same torque as the target voltage vector between the q-axis and the termination vector of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage such that the q-axis current is positive and the d-axis current is negative; or selecting the equivalent voltage vector between the d-axis and q-axis, and controlling the q-axis voltage and d-axis voltage such that the q-axis current is negative and the d-axis current is positive and greater than... Where Ψf is the magnetic flux linkage, and Ld and Lq are the inductance values ​​of the d-axis and q-axis, respectively.

[0011] Optionally, in one embodiment, the fault-tolerant control method further includes: within the third working region, along the counterclockwise direction of motor rotation, starting from the point where the d-axis coincides with the starting vector of the available voltage vector range, and ending when the q-axis coincides with the ending vector of the available voltage vector range, controlling the q-axis voltage and d-axis voltage within this region so that the d-axis current is positive and the q-axis current is 0 to control the multiphase motor.

[0012] In one embodiment, preferably, in the fourth working region, the step of determining an equivalent voltage vector that produces the same torque as the target voltage vector based on a preset strategy to control the multiphase motor further includes: selecting the equivalent voltage vector between the d-axis and the termination vector of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage such that the q-axis current is negative and the d-axis current is positive and greater than 0.5%. Where Ψf is the magnetic flux linkage, and Ld and Lq are the inductance values ​​of the d-axis and q-axis, respectively.

[0013] Optionally, the fault-tolerant control method further includes: within the fourth working region, along the counterclockwise direction of motor rotation, starting from the point where the q-axis coincides with the termination vector of the available voltage vector range, and ending at the point where the q-axis coincides with the reverse extension line of the starting vector of the available voltage vector range, controlling the q-axis voltage and d-axis voltage within this region so that the d-axis current is positive and the q-axis current is 0 to control the multiphase motor.

[0014] In one embodiment, preferably, in the fifth working region, determining the equivalent voltage vector that produces the same torque as the target voltage vector based on a preset strategy to control the multiphase motor includes: selecting the equivalent voltage vector between the reverse extension of the q-axis and the starting vector of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage so that the q-axis current is positive and the d-axis current is negative.

[0015] In one embodiment, optionally, in the fifth working area, the fault-tolerant control method further includes: directly selecting the 000 basic voltage vector in the voltage vector space as the equivalent voltage vector to control the multiphase motor.

[0016] In one embodiment, optionally, in the fifth working area, the fault-tolerant control method further includes: disconnecting all non-faulty switching transistors and waiting for the freewheeling process to end in order to control the multiphase motor.

[0017] Another aspect of the present invention provides a fault-tolerant control device for a multiphase motor, for use in a drive circuit composed of the multiphase motor and a corresponding multiphase inverter bridge, wherein the multiphase inverter bridge experiences a phase loss fault, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all on the same half of the voltage vector space. The fault-tolerant control device includes: a memory; and a processor coupled to the memory, the processor being configured to execute the fault-tolerant control method for the multiphase motor described in any of the above embodiments.

[0018] The present invention also provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, implements the fault-tolerant control method for the multiphase motor described in any of the above claims. Attached Figure Description

[0019] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0020] Figure 1 This is a drive circuit consisting of a three-phase motor and a three-phase inverter bridge, illustrated according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the basic vector voltage in the voltage vector space of a three-phase inverter bridge under normal operating mode;

[0022] Figure 3 This is a schematic diagram of the available voltage vector in a three-phase inverter bridge under the conditions of U-phase upper bridge open circuit or U-phase lower bridge short circuit.

[0023] Figure 4 This is a schematic diagram of the available voltage vector in a three-phase inverter bridge under the conditions of U-phase upper bridge short circuit or U-phase lower bridge open circuit.

[0024] Figure 5 This is a schematic flowchart illustrating a fault-tolerant control method for a multiphase motor according to an embodiment of the present invention.

[0025] Figure 6 , Figure 7 , Figure 8 These are schematic diagrams illustrating the starting position, interior of the region, and ending position of a first working area according to an embodiment of the present invention.

[0026] Figure 9 , Figure 10 , Figure 11 These are schematic diagrams illustrating the starting position, interior, and ending position of the second working area according to an embodiment of the present invention.

[0027] Figure 12 , Figure 13 , Figure 14 These are schematic diagrams illustrating the starting position, interior, and ending position of the third working area according to an embodiment of the present invention.

[0028] Figure 15 , Figure 16 , Figure 17 These are schematic diagrams illustrating the starting position, interior of the region, and ending position of the fourth working area according to an embodiment of the present invention.

[0029] Figure 18 , Figure 19 , Figure 20 These are schematic diagrams illustrating the starting position, interior, and ending position of the fifth working area according to an embodiment of the present invention; and

[0030] Figure 21 This is a schematic diagram of the fault-tolerant control device for a multiphase motor according to another aspect of the present invention.

[0031] For clarity, a brief explanation of the reference numerals in the accompanying drawings is provided below:

[0032] 1001 Three-phase motor

[0033] 1002 Three-phase inverter bridge Detailed Implementation

[0034] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a thorough understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood as the orientations shown in the relevant paragraphs and accompanying drawings. These relative terms are for illustrative purposes only and do not imply that the described apparatus must be manufactured or operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0037] It is understood that although terms such as "first," "second," and "third" may be used herein to describe various components, regions, layers, and / or parts, these components, regions, layers, and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers, and / or parts. Therefore, the first components, regions, layers, and / or parts discussed below may be referred to as second components, regions, layers, and / or parts without departing from some embodiments of the present invention.

[0038] To overcome the aforementioned deficiencies in the existing technology, the present invention provides a fault-tolerant control method and apparatus for a multiphase motor, which can realize fault-tolerant control of a multiphase motor without adding additional components or changing the hardware structure, thereby effectively improving the reliability of the electric drive system of electric vehicles while saving costs.

[0039] The fault-tolerant control method and apparatus for a multiphase motor provided by the present invention are used in a drive circuit composed of the multiphase motor and the corresponding multiphase inverter bridge. When the switching transistor in the multiphase inverter bridge of the drive circuit experiences a short circuit or open circuit fault, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all on the same half of the voltage vector space, the fault-tolerant control method provided by the present invention can be applied.

[0040] The following explanation uses a drive circuit consisting of a three-phase motor and a three-phase inverter bridge as an example.

[0041] Figure 1 This is a drive circuit consisting of a three-phase motor and a three-phase inverter bridge, illustrated according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the basic vector voltage in the voltage vector space of a three-phase inverter bridge under normal operating mode.

[0042] Please refer to Figure 1 The drive circuit consisting of a three-phase motor 1001 and a three-phase inverter bridge 1002 includes six switching transistors U1, U2, V1, V2, W1, and W2. The combination of turning these six transistors on and off can generate the following: Figure 2 The eight spatial vectors shown.

[0043] Please refer to this again. Figure 2 These eight space vectors include six valid basic voltage vectors (100, 110, 010, 011, 001, 101) and two zero vectors (000, 111). The default motor rotation direction is... Figure 2 The direction indicated by the curved arrow in the middle is counterclockwise.

[0044] It should be noted that the three-phase motor and three-phase inverter bridge described here are illustrative examples and not intended to limit the scope of protection of this invention. In fact, the fault-tolerant control method provided by this invention is not limited to three-phase motors; similar methods and principles can also be applied to multi-phase motors with more phases for fault-tolerant control. Similarly, the counter-clockwise rotation direction of the motor is also illustrative. In practical applications, motors rotating in any direction can be controlled using the fault-tolerant control method provided by this invention, achieving enhanced reliability of the drive circuit without additional changes to the hardware structure.

[0045] When a switch in the inverter fails, the effective available voltage vector and zero vector in the corresponding voltage vector space will change. The following explains the change in the space voltage vector when the inverter bridge fails.

[0046] Figure 3 This is a schematic diagram of the available voltage vector in a three-phase inverter bridge under the conditions of U-phase upper bridge open circuit or U-phase lower bridge short circuit. Figure 4This is a schematic diagram of the available voltage vector in a three-phase inverter bridge under the conditions of U-phase upper bridge short circuit or U-phase lower bridge open circuit.

[0047] by Figure 1 Taking phase U in an inverter bridge as an example, when the upper bridge switch U1 of phase U is open-circuited or experiences an open-circuit fault, the lower bridge switch U2 of phase U can be controlled to remain in the conducting state. At this time, the available basic voltage vector is as follows: Figure 3 As indicated by the thick arrows, this includes three valid basic voltage vectors: 010, 011, and 001, and one zero vector: 000. Furthermore, when the lower bridge switch U2 of phase U is short-circuited or experiences a short-circuit fault, the upper bridge switch U1 of phase U can be controlled to remain in the off state. In this case, the available basic voltage vectors are also as follows... Figure 3 As shown, in a three-phase inverter bridge, the available basic voltage vectors corresponding to these two fault states in the voltage vector space are the same.

[0048] Please continue to combine Figure 1 When the upper bridge switch U1 of phase U is short-circuited or experiences a short-circuit fault, the lower bridge switch U2 of phase U can be controlled to remain in the off state. Correspondingly, the available basic voltage vector is as follows: Figure 4 As shown, this includes three effective basic voltage vectors 110, 100, and 101, and one zero vector 111. Similarly, when the lower bridge switch U2 of phase U is open-circuited or experiences an open-circuit fault, the upper bridge switch U1 of phase U is kept in the on state, and the available basic voltage vectors are as follows. Figure 4 As shown, this means that the available basic voltage vectors corresponding to these two fault states in the voltage vector space are also the same.

[0049] Similarly, if a switch in phase V or phase W of a three-phase inverter bridge fails, the principle is similar to that of phase U, which will not be repeated here. From the above examples, it can be seen that if any one of the six switches in a three-phase inverter experiences a short circuit or open circuit fault, it can be controlled according to the above method, and correspondingly, a valid basic voltage vector and zero vector will be generated in the voltage vector space.

[0050] For the sake of simplicity, this article has... Figure 3 The fault-tolerant control method of the present invention is illustrated using the fault scenario in the illustrated embodiment as an example. For other fault scenarios of the V phase and W phase, as well as similar faults of multi-phase motors, the fault-tolerant control method provided in the embodiments below can be used for control.

[0051] Figure 5 This is a schematic flowchart illustrating a fault-tolerant control method for a multiphase motor according to an embodiment of the present invention.

[0052] Please refer to Figure 5 The fault-tolerant control method 500 for a multiphase motor provided by the present invention includes:

[0053] Step 501: Determine the range of available voltage vectors in the voltage vector space based on the controllable voltage vector.

[0054] Can be combined Figure 3 The usable voltage vector range is the region formed by the effective voltage vectors; more specifically, in Figure 3 In the embodiment shown, the available voltage vector range is the acute-angled sector region enclosed by the basic voltage vectors 010 and 001. With the motor rotating in a counterclockwise direction, the starting vector of this available voltage vector range is the basic voltage vector 010, and the ending vector is the basic voltage vector 001.

[0055] Please continue to refer to Figure 5 The fault-tolerant control method 500 for multiphase motors provided by the present invention further includes:

[0056] Step 502: Determine the target voltage vector Us based on the current vehicle torque command.

[0057] More specifically, the current vector Is can be calculated based on the current vehicle torque command, and then the target voltage vector Us can be calculated based on the current current vector Is. As will be readily understood by those skilled in the art, since the currently available voltage vector range is the acute-angled sector region enclosed by the basic voltage vectors 010 and 001, if Us exceeds this range, it cannot be output. In this case, the fault-tolerant control method provided by this invention is required.

[0058] Please continue to refer to Figure 5 The fault-tolerant control method 500 for multiphase motors provided by the present invention further includes:

[0059] Step 503: Based on the relative positional relationship between the rotor flux direction, the target voltage vector, and the available voltage vector range, determine the equivalent voltage vector of the target voltage vector within the available voltage vector range to control the multiphase motor, thereby achieving fault-tolerant control of the multiphase motor.

[0060] In one embodiment, preferably, determining the equivalent voltage vector of the target voltage vector within the available voltage vector range based on the relative positional relationship between the rotor flux direction, the target voltage vector, and the available voltage vector range to control the multiphase motor may include: setting a d-axis and a q-axis in the voltage vector space, wherein the d-axis is the rotor flux direction, and the q-axis leads the d-axis by 90° along the motor rotation direction; as the multiphase motor rotates, dividing the voltage vector space into multiple working regions based on the relative positional relationship between the target voltage vector, the d-axis, the q-axis, and the available voltage vector range; and determining the equivalent voltage vector of the target voltage vector within each working region based on a preset strategy to control the multiphase motor.

[0061] In the fault-tolerant control method for multiphase motors provided by this invention, d-axis and q-axis are introduced into the voltage vector space. This can be referenced in the reference. Figure 6 , Figure 6 This is a schematic diagram illustrating the starting position of the first working region in the voltage vector space according to an embodiment of the present invention. Figure 6 As shown, the d-axis represents the rotor flux linkage direction, and the q-axis leads the d-axis by 90° along the motor rotation direction. As the motor rotates counterclockwise, the target voltage vector, the d-axis, and the q-axis all rotate counterclockwise within this vector space. The fault-tolerant control method provided by this invention divides the voltage vector space into multiple working regions, and within each working region, determines the equivalent voltage vector of the target voltage vector based on a preset strategy to achieve fault-tolerant control.

[0062] More specifically, in this embodiment of the invention, the multiphase motor is a three-phase motor. If a short circuit or open circuit fault occurs in one of the switching transistors in the multiphase inverter bridge, it can be combined with... Figure 6 The target voltage vector U s Located in the second quadrant of the coordinate system formed by the d-axis and the q-axis, as the three-phase motor rotates counterclockwise, the target voltage vector, the d-axis, and the q-axis also rotate in the voltage vector space along the direction of the motor's rotation. To ensure the motor can rotate normally and the torque direction is controllable, the motor's rotation is divided into 5 working regions. The division of each working region and the specific control strategy are explained below.

[0063] Figure 7 , Figure 8 These are schematic diagrams illustrating the interior and termination positions of the first working area according to an embodiment of the present invention.

[0064] Please combine Figure 6 , Figure 7 , Figure 8 In the fault-tolerant control method provided by the present invention, as the motor rotates counterclockwise, the first working region begins in response to the d-axis coinciding with the reverse extension of the starting vector (i.e., the basic voltage vector 010) of the available voltage vector range; the first working region ends in response to the target voltage vector Us coinciding with the starting vector (i.e., the basic voltage vector 001) of the available voltage vector range.

[0065] Since the target voltage vector U at this time s Since the voltage vector is outside the available range and therefore cannot output, in order to achieve equivalent fault-tolerant control, the following formula can be used to control physical quantities to obtain equivalent control torque:

[0066] Ud=-wrLqiq·······················Eq1

[0067] Uq=wrLdid+wrΨf························Eq2

[0068]

[0069] Where Ud and id are the voltage and current on the d-axis, respectively; Uq and iq are the voltage and current on the q-axis, respectively; wr is the rotational angular velocity; Ψf is the magnetic flux linkage; Ld and Lq are the inductance values ​​on the d-axis and q-axis, respectively; Te is the torque; and P is the number of pole pairs.

[0070] Specifically, in this embodiment, preferably, in the first working area, determining the equivalent voltage vector of the target voltage vector based on a preset strategy to control the multiphase motor includes:

[0071] An equivalent voltage vector with the same torque as the target voltage vector Us is selected between the reverse extension line of the d-axis and the termination vector 001 of the available voltage vector range. The q-axis voltage and d-axis voltage are controlled so that the q-axis current is positive and the d-axis current is negative. Alternatively, an equivalent voltage vector with the same torque as the target voltage vector Us is selected between the reverse extension line of the d-axis and the starting vector 010 of the available voltage vector range. The q-axis voltage and d-axis voltage are controlled so that the q-axis current is positive and the d-axis current is negative. The desired output equivalent voltage vector can be adjusted by adjusting the vector's duration and intensity. These two control strategies enable the motor to output positive torque within the first working region, thereby achieving equivalent fault-tolerant control within the first working region.

[0072] Figure 9 , Figure 10 , Figure 11 These are schematic diagrams illustrating the starting position, interior, and ending position of the second working area according to an embodiment of the present invention.

[0073] Please refer to Figures 9-11 In the fault-tolerant control method provided by this invention, as the motor rotates counterclockwise, the second working region begins in response to the target voltage vector Us coinciding with the starting vector 010 of the available voltage vector range; the second working region ends in response to the target voltage vector Us coinciding with the ending vector 001 of the available voltage vector range. It is readily understood that within the second working region, the target voltage vector Us falls within the available voltage vector range, allowing the multiphase motor to operate normally and perform SVPWM modulation.

[0074] Figure 12 , Figure 13 , Figure 14These are schematic diagrams illustrating the starting position, interior, and ending position of the third working area according to an embodiment of the present invention.

[0075] Please refer to Figures 12-14 In the fault-tolerant control method provided by the present invention, as the motor rotates counterclockwise, the third working region begins in response to the target voltage vector Us coinciding with the termination vector 001 of the available voltage vector range; the third working region ends in response to the q-axis coinciding with the termination vector 001 of the available voltage vector range.

[0076] In this third working region, the target voltage vector Us is outside the basic voltage vectors 010 and 001, that is, outside the range of available voltage vectors, so Us cannot be modulated in the third working region.

[0077] In this embodiment, preferably, in the third working region, the determination of the equivalent voltage vector of the target voltage vector based on a preset strategy to control the multiphase motor may further include: selecting the equivalent voltage vector that produces the same torque as the target voltage vector Us between the q-axis and the termination vector 001 of the available voltage vector range, and controlling the voltage vector duration of the q-axis voltage and d-axis voltage so that the q-axis current is positive and the d-axis current is negative; or selecting the equivalent voltage vector between the d-axis and q-axis, and controlling the q-axis voltage and the d-axis voltage so that the q-axis current is negative and the d-axis current is positive and greater than 0.5%. Where Ψf is the magnetic flux linkage, and Ld and Lq are the inductance values ​​of the d-axis and q-axis, respectively, with Ld being less than Lq. Using these two control strategies ensures an equivalent positive output torque.

[0078] It is easy to understand, according to the formula P is the pole pair number, Ψf is the flux linkage, id is the d-axis current, iq is the q-axis current, and Ld and Lq are the d-axis and q-axis inductances, respectively, with Ld being less than Lq. Therefore, when iq is negative, Ψf*iq is also negative, and id must be greater than 1. Only in this way can the torque be guaranteed to be positive. However, if the voltage vector between the d-axis and the basic voltage vector 010 is used, the projection of this voltage vector on the d-axis is positive and the projection on the q-axis is negative. Therefore, iq is negative and id is also negative, resulting in negative torque, which does not meet the requirements and cannot achieve equivalent fault-tolerant control.

[0079] In addition, within the third working area, the fault-tolerant control method provided by the present invention may further include: along the counterclockwise direction of motor rotation, starting from the point where the d-axis coincides with the starting vector 010 of the available voltage vector range, and ending when the q-axis coincides with the ending vector 001 of the available voltage vector range, controlling the q-axis voltage and d-axis voltage within this area so that the d-axis current is positive and the q-axis current is 0, thereby controlling the multiphase motor.

[0080] Those skilled in the art will understand that, under this control method, according to the torque formula, when iq is zero, the torque is also zero. Therefore, the control of this multiphase motor can also be referred to as 0Nm control. The voltage vector used here is between 010 and 001, rather than using the zero vector 000, thus avoiding the generation of negative torque.

[0081] Figure 15 , Figure 16 , Figure 17 These are schematic diagrams illustrating the starting position, interior, and ending position of the fourth working area according to an embodiment of the present invention.

[0082] Please refer to Figures 15-17 In the fault-tolerant control method provided by the present invention, as the motor rotates counterclockwise, the fourth working region begins in response to the q-axis coinciding with the termination vector 001 of the available voltage vector range; the fourth working region ends in response to the q-axis coinciding with the reverse extension line of the starting vector 010 of the available voltage vector range.

[0083] In the fourth working region, preferably, determining the equivalent voltage vector that produces the same torque as the target voltage vector based on a preset strategy to control the multiphase motor may further include: selecting the equivalent voltage vector between the d-axis and the termination vector 001 of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage such that the q-axis current is negative and the d-axis current is positive and greater than 0.5%. Where Ψf is the magnetic flux linkage, and Ld and Lq are the inductance values ​​of the d-axis and q-axis, respectively.

[0084] Those skilled in the art will understand that within this fourth working region, the projections of voltage vectors within the available voltage vector range onto the d-axis are all positive. Therefore, according to Eq.1 above, if iq is negative, id must be positive and greater than [a certain value]. Furthermore, based on the formula Eq.2 above, it can be deduced that the projection of the voltage vector onto the q-axis must be greater than [the value of the projection]. In other words, the voltage vector used must be projected onto the q-axis as a positive value. Therefore, the voltage vector used in this fourth working region is the voltage vector between the d-axis and the basic voltage vector 001.

[0085] In addition, within the fourth working region, the fault-tolerant control method provided by the present invention may further include: starting from the point where the q-axis coincides with the termination vector 001 of the available voltage vector range along the counterclockwise direction of the motor rotation, and ending at the point where the q-axis coincides with the reverse extension line of the starting vector 010 of the available voltage vector range, controlling the q-axis voltage and d-axis voltage within this region so that the d-axis current is positive and the q-axis current is 0 to control the multiphase motor.

[0086] Similar to the 0Nm control in the third operating region, 0Nm control can also be used in the fourth operating region, specifically in the area from when the q-axis coincides with 001 to when the q-axis coincides with the reverse extension of 010. In this case, the d-axis current id is set to positive, and the q-axis current iq is set to zero. According to the torque formula, when iq is zero, the torque is also zero, hence the name 0Nm control. The voltage vector used here is between 010 and 001, rather than the zero vector 000, thus avoiding the generation of negative torque.

[0087] Figure 18 , Figure 19 , Figure 20 These are schematic diagrams illustrating the starting position, interior, and ending position of the fifth working area according to an embodiment of the present invention.

[0088] Please refer to Figures 18-20 In the fault-tolerant control method provided by the present invention, as the motor rotates counterclockwise, the fifth working region begins in response to the q-axis coinciding with the reverse extension of the starting vector 010 of the available voltage vector range; the fifth region ends in response to the d-axis coinciding again with the reverse extension of the starting vector 010 of the available voltage vector range.

[0089] In the fifth working area, preferably, the method of determining the equivalent voltage vector that produces the same torque as the target voltage vector based on a preset strategy to control the multiphase motor may further include: selecting the equivalent voltage vector between the reverse extension line of the q-axis and the starting vector 010 of the available voltage vector range, and controlling the q-axis voltage and d-axis voltage so that the q-axis current is positive and the d-axis current is negative, so as to ensure that the torque is positive.

[0090] Understandably, if the voltage vector between the q-axis extension and the basic voltage vector 001 is used, and the Ud projected onto the d-axis is positive, then the q-axis current is negative. At the same time, if the Uq projected onto the q-axis is negative, then the d-axis current is negative, which will generate negative torque, which does not meet the requirements.

[0091] In practical applications, implementing the above control methods within the fifth working area is difficult. Therefore, this invention also provides alternative control schemes within the fifth working area. Although these alternative schemes cannot achieve completely equivalent operation, they can still achieve the fault-tolerant control effect of this invention to a certain extent from an overall perspective.

[0092] For example, in one embodiment, in the fifth working region, the fault-tolerant control method may further include: directly selecting the 000 basic voltage vector in the voltage vector space as the equivalent voltage vector to control the multiphase motor.

[0093] In other words, in this embodiment, references can be used. Figure 1 This allows the lower tubes of phases V and W to be in a conducting state, while the lower tube of phase U is short-circuited. In this 000 mode, negative torque will always be generated in the fifth region. However, in terms of the entire rotation cycle, since positive torque can be ensured in the other four working regions, the average torque is still positive, and the fault-tolerant control of this invention can still be achieved.

[0094] In addition, in another embodiment, in the fifth working area, the fault-tolerant control method may further include: disconnecting all non-faulty switching transistors and waiting for the freewheeling process to end in order to control the multiphase motor.

[0095] You can refer to the following: Figure 1 As those skilled in the art will understand, due to the short-circuit fault in the lower U-phase transistor, even if the drive of the lower U-phase transistor is disconnected, the lower U-phase transistor remains in a short-circuit state. However, within this fifth operating region, the other five switching transistors are controllable, and their drives can be disconnected, putting them in an off-mode. At this time, the current in the three-phase inductors of the motor will freewheel back into the power supply. Although this process is accompanied by the generation of negative torque, once the freewheeling process ends, because the three-phase currents are all zero, the torque will remain zero. Thus, fault-tolerant control of the multiphase motor can be achieved even during the positive cycle of rotor rotation.

[0096] The fault-tolerant control method for multiphase motors provided by this invention allows for fault-tolerant control of the motor even after a short circuit or open circuit fault occurs in a switching transistor of the inverter bridge in the drive circuit, achieving the fault-tolerant control function without incurring additional hardware costs. Furthermore, this method is not limited to three-phase motors; it can be extended to various multiphase motor applications. It can be used for both forward and reverse drives, and is applicable not only to electric vehicle drive systems but also to inverter fault-tolerant control in other motor control applications, facilitating widespread adoption.

[0097] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0098] Another aspect of the present invention provides a fault-tolerant control device for a multiphase motor, for use in a drive circuit composed of the multiphase motor and a corresponding multiphase inverter bridge, wherein the multiphase inverter bridge experiences a phase loss fault, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all on the same half of the voltage vector space. The fault-tolerant control device includes: a memory; and a processor coupled to the memory, the processor being configured to execute the fault-tolerant control method for the multiphase motor described in any of the above embodiments.

[0099] Figure 21 This is a schematic diagram of the fault-tolerant control device for a multiphase motor according to another aspect of the present invention.

[0100] like Figure 21 As shown, the fault-tolerant control device 2100 for a multiphase motor provided in this embodiment may include a memory 2101 and a processor 2102 coupled to the memory 2101. The processor 2102 may be configured to implement any of the fault-tolerant control methods for the multiphase motor described above.

[0101] According to another aspect of the invention, an embodiment of a computer storage medium is also provided herein.

[0102] The computer storage medium contains a computer program. When executed by a processor, this computer program can implement the steps of any of the aforementioned fault-tolerant control methods for multiphase motors.

[0103] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps are described above in a generalized manner in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as departing from the scope of the invention.

[0104] The processors described herein can be implemented using electronic hardware, computer software, or any combination thereof. Whether such processors are implemented as hardware or software will depend on the specific application and the overall design constraints imposed on the system. As an example, the processors, any portion thereof, or any combination thereof presented in this disclosure can be implemented using microprocessors, microcontrollers, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuitry, and other suitable processing components configured to perform the various functions described throughout this disclosure. The functionality of the processors, any portion thereof, or any combination thereof presented in this disclosure can be implemented using software executed by a microprocessor, microcontroller, DSP, or other suitable platform.

[0105] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor such that the processor can read and write information to / from the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside as discrete components in the user terminal.

[0106] In one or more exemplary embodiments, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functionality may be stored or transmitted as one or more instructions or code on or through a computer-readable medium. A computer-readable medium includes both computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium accessible to a computer. By way of example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and is accessible to a computer. Any connection is also legitimately referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of a medium. As used in this article, disk and disc include compact discs (CDs), laser discs, optical discs, digital multi-purpose discs (DVDs), floppy disks, and Blu-ray discs. Disks typically reproduce data magnetically, while discs reproduce data optically using lasers. Combinations of these should also be included within the scope of computer-readable media.

[0107] The prior description of this disclosure is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fault-tolerant control method for a multiphase motor, used in a drive circuit composed of the multiphase motor and a corresponding multiphase inverter bridge, wherein a short-circuit or open-circuit fault occurs in the switching transistors of the multiphase inverter bridge, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all on the same half of the voltage vector space, the fault-tolerant control method comprising: The range of available voltage vectors is determined in the voltage vector space based on the controllable voltage vector. Determine the target voltage vector based on the current vehicle torque command; as well as The equivalent voltage vector of the target voltage vector is determined within the available voltage vector range based on the relative positional relationship between the rotor flux direction, the target voltage vector, and the available voltage vector range, in order to control the multiphase motor.

2. The fault-tolerant control method as described in claim 1, characterized in that, The method of determining the equivalent voltage vector of the target voltage vector within the available voltage vector range based on the relative positional relationship between the rotor flux direction, the target voltage vector, and the available voltage vector range to control the multiphase motor includes: In the voltage vector space, a d-axis and a q-axis are defined, wherein the d-axis is the direction of the rotor flux linkage, and the q-axis leads the d-axis by 90° along the motor rotation direction; As the multiphase motor rotates, the voltage vector space is divided into multiple working regions based on the relative positions of the target voltage vector, the d-axis, the q-axis, and the available voltage vector range; and In each working area, the equivalent voltage vector of the target voltage vector is determined based on a preset strategy to control the multiphase motor.

3. The fault-tolerant control method as described in claim 2, characterized in that, The multiphase motor is a three-phase motor. A short circuit or open circuit fault occurs in one of the switching transistors in the multiphase inverter bridge. The target voltage vector is located in the second quadrant of the coordinate system formed by the d-axis and the q-axis. As the three-phase motor rotates counterclockwise, the target voltage vector, the d-axis, and the q-axis also rotate in the voltage vector space along the direction of motor rotation. Based on the relative positional relationship of the target voltage vector, the d-axis, the q-axis, and the available voltage vector range, the voltage vector space is divided into five working regions. Among these, the region along the counterclockwise direction of motor rotation... The first working region begins in response to the d-axis coinciding with the reverse extension of the starting vector of the available voltage vector range; In response to the target voltage vector coinciding with the starting vector of the available voltage vector range, the first working region ends and the second working region begins, during which the multiphase motor operates normally; In response to the target voltage vector coinciding with the termination vector of the available voltage vector range, the second working region ends and the third working region begins; The third working region ends and the fourth working region begins in response to the q-axis coinciding with the termination vector of the available voltage vector range; In response to the q-axis coinciding with the reverse extension of the starting vector of the available voltage vector range, the fourth working region ends and the fifth working region begins; and The fifth working region ends when the reverse extension of the d-axis and the starting vector of the available voltage vector range coincides again.

4. The fault-tolerant control method as described in claim 3, characterized in that, In the first working area, determining the equivalent voltage vector of the target voltage vector based on a preset strategy to control the multiphase motor includes: Between the reverse extension of the d-axis and the termination vector of the available voltage vector range, select an equivalent voltage vector that produces the same torque as the target voltage vector, and control the q-axis voltage and d-axis voltage such that the q-axis current is positive and the d-axis current is negative; or Between the reverse extension of the d-axis and the starting vector of the available voltage vector range, an equivalent voltage vector that produces the same torque as the target voltage vector is selected, and the q-axis voltage and the d-axis voltage are controlled such that the q-axis current is positive and the d-axis current is negative.

5. The fault-tolerant control method as described in claim 3, characterized in that, In the third working area, the step of determining the equivalent voltage vector of the target voltage vector based on a preset strategy to control the multiphase motor further includes: Select an equivalent voltage vector that produces the same torque as the target voltage vector between the q-axis and the termination vector of the available voltage vector range, and control the q-axis voltage and d-axis voltage such that the q-axis current is positive and the d-axis current is negative; or The equivalent voltage vector is selected between the d-axis and q-axis, and the q-axis voltage and d-axis voltage are controlled such that the q-axis current is negative and the d-axis current is positive and greater than 0.5%. Where Ψf is the magnetic flux linkage, and Ld and Lq are the inductance values ​​of the d-axis and q-axis, respectively.

6. The fault-tolerant control method as described in claim 3, characterized in that, The fault-tolerant control method further includes: Within the third working area, along the counterclockwise direction of motor rotation, starting from the point where the d-axis coincides with the starting vector of the available voltage vector range, and ending when the q-axis coincides with the ending vector of the available voltage vector range, the q-axis voltage and d-axis voltage are controlled within this area so that the d-axis current is positive and the q-axis current is 0, thereby controlling the multiphase motor.

7. The fault-tolerant control method as described in claim 3, characterized in that, In the fourth working region, the step of determining an equivalent voltage vector that produces the same torque as the target voltage vector based on a preset strategy to control the multiphase motor further includes: The equivalent voltage vector is selected between the d-axis and the termination vector of the available voltage vector range, and the q-axis voltage and d-axis voltage are controlled such that the q-axis current is negative and the d-axis current is positive and greater than 0.5%. Where Ψf is the magnetic flux linkage, and Ld and Lq are the inductance values ​​of the d-axis and q-axis, respectively.

8. The fault-tolerant control method as described in claim 3, characterized in that, The fault-tolerant control method further includes: Within the fourth working region, along the counterclockwise direction of the motor rotation, starting from the point where the q-axis coincides with the termination vector of the available voltage vector range, and ending when the q-axis coincides with the reverse extension line of the starting vector of the available voltage vector range, the q-axis voltage and d-axis voltage are controlled within this region so that the d-axis current is positive and the q-axis current is 0 to control the multiphase motor.

9. The fault-tolerant control method as described in claim 3, characterized in that, In the fifth working area, the step of determining an equivalent voltage vector that produces the same torque as the target voltage vector based on a preset strategy to control the multiphase motor further includes: The equivalent voltage vector is selected between the reverse extension of the q-axis and the starting vector of the available voltage vector range, and the q-axis voltage and d-axis voltage are controlled such that the q-axis current is positive and the d-axis current is negative.

10. The fault-tolerant control method as described in claim 3, characterized in that, In the fifth working area, the fault-tolerant control method further includes: The 000 basic voltage vector in the voltage vector space is directly selected as the equivalent voltage vector to control the multiphase motor.

11. The fault-tolerant control method as described in claim 3, characterized in that, In the fifth working area, the fault-tolerant control method further includes: Disconnect all non-faulty switching transistors and wait for the freewheeling process to end in order to control the multiphase motor.

12. A fault-tolerant control device for a multiphase motor is used in a drive circuit composed of the multiphase motor and a corresponding multiphase inverter bridge, wherein a short-circuit or open-circuit fault occurs in the switching transistor of the multiphase inverter bridge, and the controllable voltage vectors corresponding to the multiphase inverter bridge under the current fault are all on the same half of the voltage vector space, the fault-tolerant control device comprising: Memory; as well as A processor coupled to the memory, the processor being configured to execute the fault-tolerant control method for a multiphase motor as described in any one of claims 1 to 11.

13. A computer-readable medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the fault-tolerant control method for a multiphase motor as described in any one of claims 1 to 11.

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