CN115085621A

CN115085621A - Method and device for determining initial angle of permanent magnet synchronous motor rotor and motor

Info

Publication number: CN115085621A
Application number: CN202210901644.2A
Authority: CN
Inventors: 苗强; 徐亚美; ***
Original assignee: Weichai Power Co Ltd; Weifang Weichai Power Technology Co Ltd
Current assignee: Weichai Power Co Ltd; Weifang Weichai Power Technology Co Ltd
Priority date: 2022-07-28
Filing date: 2022-07-28
Publication date: 2022-09-20

Abstract

The application provides a method and a device for determining an initial angle of a permanent magnet synchronous motor rotor and a motor. Acquiring a two-phase voltage signal; converting the two-phase voltage signal into a two-phase current signal; converting the two-phase current signal into a three-phase current signal, wherein the three-phase current signal is represented by a three-phase coordinate system, three coordinate axes in the three-phase coordinate system are coplanar, and an included angle between any two coordinate axes is larger than 0 degree; and determining the initial angle of the rotor according to the three-phase current signals. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively.

Description

Method and device for determining initial angle of permanent magnet synchronous motor rotor and motor

Technical Field

The application relates to the technical field of permanent magnet synchronous motors, in particular to a method and a device for determining an initial angle of a rotor of a permanent magnet synchronous motor and a motor.

Background

The permanent magnet synchronous motor has the advantages of high power density, high efficiency, energy conservation and the like, and is widely applied to the field of motor controllers, while the permanent magnet synchronous motors such as commercial vehicle oil pumps and air pumps can cancel a position sensor due to the consideration of reducing cost and space occupation, so that the rotor position signal calibration is needed, and the initial angle at zero speed needs to be detected in order to improve the load carrying capacity of the permanent magnet synchronous motor.

At present, the pulse input method is adopted to detect the initial angle, and multiple times of coordinate transformation and current-voltage signal transformation are needed. Resulting in inaccurate sampling points during sampling and thus less accurate initial angle of the rotor.

Disclosure of Invention

The application mainly aims to provide a method and a device for determining an initial angle of a rotor of a permanent magnet synchronous motor and the motor, so as to solve the problem that the accuracy of the initial angle of the rotor is low in the prior art.

According to an aspect of the embodiments of the present invention, there is provided a method for determining an initial angle of a rotor of a permanent magnet synchronous motor, including: acquiring a two-phase voltage signal, wherein the two-phase voltage signal is obtained by performing two-phase representation on an input voltage signal, and the input voltage signal is a voltage signal input to a stator of a permanent magnet synchronous motor to be detected; converting the two-phase voltage signal into a two-phase current signal; converting the two-phase current signals into three-phase current signals, wherein the three-phase current signals are represented by a three-phase coordinate system, three coordinate axes in the three-phase coordinate system are coplanar, an included angle between any two coordinate axes is larger than 0 degrees, and the directions of any two coordinate axes are different; and determining the initial angle of the rotor according to the three-phase current signals.

Optionally, converting the two-phase voltage signal into a two-phase current signal includes: obtaining a resistance value of a resistor in the stator, a first inductance on a d-axis of a two-phase coordinate system, a second inductance on a q-axis of the two-phase coordinate system, a duration of a high level of the input voltage signal, a target duration, a first angle, a second angle, and an angle difference value, where the first angle is a target included angle before the input voltage signal is input to the stator, the second angle is the target included angle after the input voltage signal is input to the stator, the angle difference value is a difference value between the first angle and the second angle, the target included angle is an included angle between the d-axis of the two-phase coordinate system and a d-axis of a standard coordinate system, a direction of the d-axis of the two-phase coordinate system is a direction from an S-pole to an N-pole of a winding of the stator, and the q-axis of the two-phase coordinate system is perpendicular to the d-axis of the two-phase coordinate system, the direction of the d axis of the standard coordinate system is parallel to the transverse symmetrical axis of the stator, and the q axis of the standard coordinate system is perpendicular to the d axis of the standard coordinate system; and constructing a first relational expression according to the input voltage signal, the resistance value, the first inductor, the second inductor, the duration of the high level of the input voltage signal, the target time length and the angle difference value, and converting the two-phase voltage signal into a two-phase current signal by at least adopting the first relational expression.

Optionally, converting the two-phase voltage signal into a two-phase current signal using at least the first relation comprises: constructing a voltage conversion relation:

t≤t ₀ wherein u is _d Representing the voltage component, u, of the two-phase voltage signal on the d-axis of the two-phase coordinate system _q Representing a voltage component, U, of said two-phase voltage signal on the q-axis of said two-phase coordinate system _m Representing the input voltage signal, t representing the duration of the high level of the input voltage signal, t ₀ Representing the target duration; using the first relationship:

t≤t ₀ converting the two-phase voltage signal in relation to the voltage conversionIs the two-phase current signal, wherein i _d Representing a current component, i, of the two-phase current signal on a d-axis of the two-phase coordinate system _q Represents a current component of the two-phase current signal on a q-axis of the two-phase coordinate system, R represents the resistance value,

represents the angular difference, L _d Represents the first inductance, L _q Representing the second inductance.

Optionally, converting the two-phase current signal into a three-phase current signal includes: constructing a second relation based on the two-phase current signal and the second angle; using the second relationship:

converting the two-phase current signal into the three-phase current signal, wherein i _A Representing a first current signal, i, on a first coordinate axis of said three-phase coordinate system _B Representing a second current signal, i, on a second coordinate axis of said three-phase coordinate system _C And represents a third current signal on a third coordinate axis of the three-phase coordinate system, and theta represents the second angle.

Optionally, the method further comprises: constructing a third relation according to the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference; and determining the second angle and the angle difference value by adopting the third relation and the first current signal on the first coordinate axis of the three-phase coordinate system.

Optionally, determining the second angle and the angle difference value by using the third relation and the first current signal on the first coordinate axis of the three-phase coordinate system includes: using the third relationship:

and the first current signal determines the second angle and the angle difference, wherein i _A Representing said first current signal, U _m A voltage signal representing the d-axis of the input voltage signal in the two-phase coordinate system, R represents the resistance value, and L represents _d Representing said first inductance, L _q Representing the second inductance, t representing the duration of the high level of the input voltage signal, θ ^* Represents the first angle, theta represents the second angle,

representing the angular difference.

Optionally, after constructing a third relation according to the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference, the method further includes: determining whether the first inductance and the second inductance are equal; and under the condition that the first inductance and the second inductance are equal, determining that the second angle detection fails, and generating first prompt information.

Optionally, after constructing a third relation according to the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference, the method further includes: determining whether a duration of a high level of the input voltage signal is greater than a first predetermined multiple of a duration threshold; and under the condition that the duration of the high level of the input voltage signal is greater than the duration threshold of the first preset multiple, determining that the second angle detection fails, and generating second prompt information.

Optionally, the determining the initial angle of the rotor according to the three-phase current signals includes: determining a maximum first angle from a plurality of the first angles based on the first current signal; and determining the initial angle of the rotor according to the maximum first angle corresponding to the first current signal, the first angle corresponding to the second current signal and the first angle corresponding to the third current signal.

Optionally, determining the initial angle of the rotor according to the maximum first angle corresponding to the first current signal, the first angle corresponding to the second current signal, and the first angle corresponding to the third current signal includes: determining a maximum first angle from a plurality of the first angles based on the second current signal; determining a maximum first angle from a plurality of the first angles based on the third current signal; and checking according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to a checking result.

Optionally, the verifying according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to a verification result includes: determining a verification condition, wherein the verification condition comprises: the maximum first angle corresponding to the second current signal is equal to a first target angle and the maximum first angle corresponding to the third current signal is equal to a second target angle; determining that the verification result representation passes verification under the condition that the verification condition is met; determining that the second angle is a second predetermined multiple of a maximum first angle corresponding to the first current signal under the condition that the verification result representation passes; determining the initial angle of the rotor to be the second angle.

According to another aspect of the embodiments of the present invention, there is also provided a device for determining an initial angle of a rotor of a permanent magnet synchronous motor, including: the device comprises an acquisition unit, a detection unit and a control unit, wherein the acquisition unit is used for acquiring a two-phase voltage signal, the two-phase voltage signal is obtained by performing two-phase representation on an input voltage signal, and the input voltage signal is a voltage signal input to a stator of the permanent magnet synchronous motor to be detected; a first conversion unit for converting the two-phase voltage signal into a two-phase current signal; the second conversion unit is used for converting the two-phase current signals into three-phase current signals, wherein a three-phase coordinate system is adopted to represent the three-phase current signals, three coordinate axes in the three-phase coordinate system are coplanar, an included angle between any two coordinate axes is larger than 0 degree, and the directions of any two coordinate axes are different; and the first determining unit is used for determining the initial angle of the rotor according to the three-phase current signals.

According to still another aspect of the embodiments of the present invention, there is also provided a motor including: the device comprises a stator, a rotor and a device for determining the initial angle of the rotor, wherein the stator is sleeved on the rotor, the device for determining the initial angle of the rotor is electrically connected with the stator and the rotor respectively, and the device for determining the initial angle of the rotor is used for executing any one of the methods.

In the embodiment of the invention, firstly, a two-phase voltage signal is obtained, then the two-phase voltage signal is converted into a two-phase current signal, then the two-phase current signal is converted into a three-phase current signal, and finally, the initial angle of the rotor is determined according to the three-phase current signal. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application. In the drawings:

fig. 1 shows a flow diagram of a method of determining an initial angle of a rotor of a permanent magnet synchronous motor according to an embodiment of the present application;

FIG. 2 shows a schematic diagram of a two-phase coordinate system according to an embodiment of the present application;

FIG. 3 shows a schematic diagram of a system for determining an initial angle of a rotor in some embodiments;

fig. 4 is a schematic structural diagram illustrating an initial angle determining apparatus of a rotor of a permanent magnet synchronous motor according to an embodiment of the present application;

fig. 5 shows a flow diagram of another method for determining an initial angle of a rotor of a permanent magnet synchronous motor according to an embodiment of the application.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Also, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element.

At present, a pulse input method is adopted to detect an initial angle, an input voltage signal is expressed on a two-phase coordinate system, the input voltage signal is expressed on a three-phase coordinate system through coordinate transformation, the input voltage signal expressed on the three-phase coordinate system is converted into a current signal, the current signal is converted into a current signal of the two-phase coordinate system, and then the initial angle is determined.

As mentioned in the background of the invention, in order to solve the above problem, the accuracy of the initial angle of the rotor in the prior art is low, and in one embodiment of the present application, a method, an apparatus and a motor for determining the initial angle of the rotor of a permanent magnet synchronous motor are provided.

According to an embodiment of the present application, a method of determining an initial angle of a rotor of a permanent magnet synchronous motor is provided.

Fig. 1 is a flowchart of a method of determining an initial angle of a rotor of a permanent magnet synchronous motor according to an embodiment of the present application. As shown in fig. 1, the method comprises the steps of:

step S101, obtaining a two-phase voltage signal, wherein the two-phase voltage signal is obtained by performing two-phase representation on an input voltage signal, and the input voltage signal is a voltage signal input to a stator of a permanent magnet synchronous motor to be detected;

step S102, converting the two-phase voltage signal into a two-phase current signal;

step S103, converting the two-phase current signals into three-phase current signals, wherein the three-phase current signals are represented by a three-phase coordinate system, three coordinate axes in the three-phase coordinate system are coplanar, an included angle between any two coordinate axes is larger than 0 degrees, and the directions of any two coordinate axes are different;

and step S104, determining the initial angle of the rotor according to the three-phase current signals.

In the method, firstly, a two-phase voltage signal is obtained, then the two-phase voltage signal is converted into a two-phase current signal, then the two-phase current signal is converted into a three-phase current signal, and finally the initial angle of the rotor is determined according to the three-phase current signal. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than here.

In an embodiment of the present application, converting the two-phase voltage signal into a two-phase current signal includes: obtaining a resistance value of a resistor in the stator, a first inductance on a d-axis of a two-phase coordinate system, a second inductance on a q-axis of the two-phase coordinate system, a duration of a high level of the input voltage signal, a target time length, a first angle, a second angle, and an angle difference, the first angle being a target angle before the input voltage signal is input to the stator, the second angle being the target angle after the input voltage signal is input to the stator, the angle difference being a difference between the first angle and the second angle, the target angle being an angle between the d-axis of the two-phase coordinate system and a d-axis of a standard coordinate system, a direction of the d-axis of the two-phase coordinate system being a direction from an S-pole to an N-pole of a winding of the stator, the q-axis of the two-phase coordinate system being perpendicular to the d-axis of the two-phase coordinate system, the direction of the d axis of the standard coordinate system is parallel to the transverse symmetrical axis of the stator, and the q axis of the standard coordinate system is vertical to the d axis of the standard coordinate system; and constructing a first relational expression according to the input voltage signal, the resistance value, the first inductor, the second inductor, the duration of the high level of the input voltage signal, the target time length and the angle difference, and converting the two-phase voltage signal into a two-phase current signal by at least adopting the first relational expression. In this embodiment, a plurality of parameter data relating to the initial angle of the rotor are collected, and a first relation is constructed based on a portion of the parameter data, according to which the two-phase voltage signal can be more accurately converted into the two-phase current signal.

In another embodiment of the present application, the converting the two-phase voltage signal into the two-phase current signal using at least the first relation includes: constructing a voltage conversion relation:

t≤t ₀ wherein u is _d A voltage component u representing the two-phase voltage signal on the d-axis of the two-phase coordinate system _q Represents a voltage component, U, of the two-phase voltage signal on the q-axis of the two-phase coordinate system _m Representing the input voltage signal, t representing the duration of the high level of the input voltage signal, t ₀ Indicating the target time length; using the first relationship:

t≤t ₀ and converting the two-phase voltage signal into the two-phase current signal according to the voltage conversion relation, wherein i _d A current component i representing the two-phase current signal on the d-axis of the two-phase coordinate system _q Represents a current component of the two-phase current signal on a q-axis of the two-phase coordinate system, R represents the resistance value,

represents the above-mentioned angular difference, L _d Represents the first inductance, L _q Representing the second inductance mentioned above. In this embodiment, for the q axis of the two-phase coordinate system, the voltage component is 0, because if there is voltage on the q axis, the rotation of the motor will be generated, and if there is voltage on the d axis, the current of the magnetic field will be generated, and no torque will be generated, so that only the d axis is divided, which further ensures that the initial angle of the rotor is calculated more accurately, and simultaneously the two-phase voltage signal can be converted into the two-phase current signal more accurately according to the voltage conversion relation and the first relation. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

In addition, the voltage conversion relation further includes:

t＞t ₀ the first relation further includes:

t＞t ₀ since t is a time parameter, and is a high level when the time is shorter than the target and a low level when the time is longer than the target, the calculation is performed using the high level. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

In another embodiment of the present application, converting the two-phase current signal into a three-phase current signal includes: constructing a second relational expression according to the two-phase current signal and the second angle; using the second relationship:

converting the two-phase current signal into the three-phase current signal, wherein i _A Representing a first current signal, i, on a first coordinate axis of said three-phase coordinate system _B Representing a second current signal, i, on a second coordinate axis of said three-phase coordinate system _C And θ represents the second angle, and represents a third current signal on a third coordinate axis of the three-phase coordinate system. In this embodiment, the two-phase current signal can be more accurately converted into the three-phase current signal by using the second relational expression, and then the initial angle of the rotor can be more accurately determined subsequently according to the three-phase current signal. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

Specifically, the two-phase coordinate system is shown in fig. 2, where the d axis in fig. 2 is a d axis in the two-phase coordinate system, α is a d axis in the standard coordinate system, the q axis is a q axis in the two-phase coordinate system, β is a q axis in the standard coordinate system, the q axis in the two-phase coordinate system is obtained by shifting the d axis of the standard coordinate system by 120 degrees to the left, and may be obtained by inverse park change, so as to obtain a second coordinate axis of the three-phase coordinate system, and then obtain the three-phase coordinate system by inverse clark conversion, and obtain a third coordinate axis of the three-phase coordinate system by 120 degrees to the right, where the first coordinate axis is the d axis of the standard coordinate system.

In addition, in some embodiments, the initial angle of the rotor is determined by an inverse park transformation and an inverse clark transformation, as shown in fig. 3, the permanent magnet synchronous motor is electrically connected with the inverse park transformation module and the inverse clark transformation module, respectively, and the angle transformation is performed by the inverse park transformation module and the inverse clark transformation module.

In yet another embodiment of the present application, the method further includes: constructing a third relation based on the two-phase voltage signal, the resistance value, the first inductance, the second inductance, a duration of a high level of the input voltage signal, the first angle, the second angle, and the angle difference; and determining the second angle and the angle difference value by using the third relation and the first current signal on the first coordinate axis of the three-phase coordinate system. In this embodiment, actually, the first angle is a known parameter, the second angle is an unknown parameter, and correspondingly, the angle difference is also an unknown parameter, so that a third relational expression is constructed, the second angle and the angle difference can be accurately determined by using the third relational expression, and then the initial angle of the rotor can be more accurately determined subsequently.

In addition, in practical applications, not only the first current signal on the first coordinate axis may be used to determine the second angle and the angle difference, but also the second current signal on the second coordinate axis and the third current signal on the third coordinate axis are also applicable, when the second current signal is used to perform the calculation, the difference due to the angle change needs to be subtracted, and when the third current signal is used to perform the calculation, the difference due to the angle change needs to be added.

In a specific embodiment of the present application, the determining the second angle and the angle difference by using the third relation and the first current signal on the first coordinate axis of the three-phase coordinate system includes: adopting the third relation:

and said first current signal determining said second angle and said angle difference, wherein i _A Representing said first current signal, U _m A d-axis voltage signal represented by the two-phase coordinate system, R represents the resistance value, and L represents the input voltage signal _d Representing the first inductance, L _q Represents the second inductance, t represents the duration of the high level of the input voltage signal, θ ^* Represents the first angle, theta represents the second angle,

indicating the angular difference. In this embodiment, after the first current signal is analyzed by using the third relational expression, the second angle and the angle difference value may be determined, and since the second angle and the angle difference value are unknown parameters, the third relational expression may be deformed, and the second angle and the angle difference value may be obtained. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

In order to further accurately detect the second angle, in an embodiment of the present application, after constructing a third relation based on the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference, the method further includes: determining whether the first inductance and the second inductance are equal; and determining that the second angle detection fails when the first inductance and the second inductance are equal to each other, and generating first prompt information.

Specifically, it can be determined from the third relation that if the first inductance and the second inductance are equal, the term e is 1, and the term after cos is 0, the angle measurement cannot be performed using the manner in which the pulse injection and the response current are performed.

In order to further accurately detect the second angle, in another embodiment of the present application, after constructing a third relation based on the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference, the method further includes: determining whether the duration of the high level of the input voltage signal is greater than a first preset multiple of a time length threshold; and determining that the second angle detection fails and generating second prompt information when the duration of the high level of the input voltage signal is greater than the duration threshold of the first preset multiple.

In particular, it can be determined from the third relation that if the duration of the high level of the input voltage signal is greater than the duration threshold of the first predetermined multiple, the three-phase current signals are only related to the first angle, and are not related to the second angle, and the initial angle of the rotor cannot be determined from the sampled values.

In addition, according to a modification of the third relation, when the duration of the high level of the input voltage signal is greater than the duration threshold of the first predetermined multiple, the following formula can be obtained:

according to the formula, the three-phase current signals can be determined to be only related to the first angle, so that the second angle cannot be determined, and the duration of the high level of the input voltage signals needs to be ensured to be short.

In another embodiment of the present invention, the determining of the initial angle of the rotor based on the three-phase current signals includes: determining a maximum first angle from a plurality of the first angles based on the first current signal; the initial angle of the rotor is determined based on a maximum first angle corresponding to the first current signal, the first angle corresponding to the second current signal, and the first angle corresponding to the third current signal. In this embodiment, the second angle is changed with the change of the first angle, so that the largest first angle of the first angles is extracted, and the initial angle of the rotor can be accurately determined. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

Specifically, let i _A ＝i _A1 +i _A2 ，

Assuming that the axis of the rotor is stationary, it can be seen from the above equations that, when the steady state is not reached, since the first angle is known, the parameters of the plurality of motors are known, i _A1 Approximated by a known quantity, i _A2 Varies with the variation of the first angle, and it can be thus determined that the first angle and the second angle satisfy θ ^* The amplitude collected is maximum at 2 θ. The three-phase current signals are processed, e.g. first current signal minus i _A1 Obtaining a current with a second angle, the first current signal only remaining i _A2 . The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

In another embodiment of the present invention, the determining the initial angle of the rotor based on a maximum first angle corresponding to the first current signal, the first angle corresponding to the second current signal, and the first angle corresponding to the third current signal includes: determining a maximum first angle from a plurality of the first angles based on the second current signal; determining a maximum first angle from a plurality of the first angles based on the third current signal; and verifying according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to a verification result. In this embodiment, in order to compare the magnitude of the current signal having the second angle and further determine the second angle, the maximum first angle of the first current signal needs to be verified by using the maximum first angle of the second current signal and the maximum first angle of the third current signal, so that it is ensured that the accuracy of the initial angle of the rotor for subsequent detection is higher.

In a specific embodiment of the present application, the verifying according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to a verification result includes: determining a checking condition, wherein the checking condition comprises the following steps: the maximum first angle corresponding to the second current signal is equal to a first target angle and the maximum first angle corresponding to the third current signal is equal to a second target angle; determining that the verification result representation passes verification under the condition that the verification condition is met; determining that the second angle is a second predetermined multiple of a maximum first angle corresponding to the first current signal when the verification result is characterized to pass; determining the initial angle of the rotor to be the second angle. In this embodiment, the maximum first angle of the first current signal is further verified, which can ensure a higher accuracy of the detected initial angle of the rotor.

In particular, the first angle at which the first current signal is maximum should be

The second angle should be

The maximum first angle corresponding to the second current signal should be

The maximum second angle corresponding to the third current signal should be

The specific relationships described above are exemplary only, and any variations fall within the scope of the present application.

It should be noted that the device for determining an initial angle of a rotor of a permanent magnet synchronous motor according to the embodiment of the present application may be used to execute the method for determining an initial angle of a rotor of a permanent magnet synchronous motor according to the embodiment of the present application. The following describes an initial angle determining apparatus for a rotor of a permanent magnet synchronous motor according to an embodiment of the present application.

Fig. 4 is a schematic view of an initial angle determining apparatus of a rotor of a permanent magnet synchronous motor according to an embodiment of the present application. As shown in fig. 4, the apparatus includes:

an obtaining unit 10, configured to obtain a two-phase voltage signal, where the two-phase voltage signal is obtained by performing two-phase representation on an input voltage signal, and the input voltage signal is a voltage signal input to a stator of a to-be-detected permanent magnet synchronous motor;

a first conversion unit 20 configured to convert the two-phase voltage signal into a two-phase current signal;

a second conversion unit 30, configured to convert the two-phase current signal into a three-phase current signal, where the three-phase current signal is represented by a three-phase coordinate system, three coordinate axes in the three-phase coordinate system are coplanar, an included angle between any two coordinate axes is greater than 0 °, and directions of any two coordinate axes are different;

and a first determining unit 40 for determining an initial angle of the rotor according to the three-phase current signals.

In the device, the obtaining unit obtains the two-phase voltage signal, the first conversion unit converts the two-phase voltage signal into the two-phase current signal, the second conversion unit converts the two-phase current signal into the three-phase current signal, and the first determining unit determines the initial angle of the rotor according to the three-phase current signal. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

In an embodiment of the present application, the first conversion unit includes an obtaining module and a first conversion module, the obtaining module is configured to obtain a resistance value of a resistor in the stator, a first inductance on a d-axis of a two-phase coordinate system, a second inductance on a q-axis of the two-phase coordinate system, a duration of a high level of the input voltage signal, a target time length, a first angle, a second angle, and an angle difference, the first angle is a target included angle before the input voltage signal is input to the stator, the second angle is a target included angle after the input voltage signal is input to the stator, the angle difference is a difference between the first angle and the second angle, the target included angle is an included angle between a d-axis of the two-phase coordinate system and a d-axis of a standard coordinate system, a direction of the d-axis of the two-phase coordinate system is a direction from an S pole to an N pole of a winding of the stator, the q axis of the two-phase coordinate system is perpendicular to the d axis of the two-phase coordinate system, the direction of the d axis of the standard coordinate system is parallel to the transverse symmetrical axis of the stator, and the q axis of the standard coordinate system is perpendicular to the d axis of the standard coordinate system; the first conversion module is configured to construct a first relation according to the input voltage signal, the resistance value, the first inductor, the second inductor, the duration of the high level of the input voltage signal, the target time duration, and the angle difference, and convert the two-phase voltage signal into a two-phase current signal by using at least the first relation. In this embodiment, a plurality of parameter data relating to the initial angle of the rotor are collected, and a first relation is constructed based on a portion of the parameter data, according to which the two-phase voltage signal can be more accurately converted into the two-phase current signal.

In another embodiment of the present application, the first conversion module includes a construction submodule and a conversion submodule, and the construction submodule is configured to construct a voltage conversion relation:

wherein u is _d A voltage component u representing the two-phase voltage signal on the d-axis of the two-phase coordinate system _q Represents a voltage component, U, of the two-phase voltage signal on the q-axis of the two-phase coordinate system _m Representing the input voltage signal, t representing the duration of the high level of the input voltage signal, t ₀ Indicating the target time length; the conversion submodule is configured to use the first relation:

represents the above-mentioned angular difference, L _d Representing the first inductance, L _q Representing the second inductance mentioned above. In this embodiment, for the q axis of the two-phase coordinate system, the voltage component is 0, because if there is voltage on the q axis, the rotation of the motor will be generated, and if there is voltage on the d axis, the current of the magnetic field will be generated, and no torque will be generated, so that only the d axis is divided, which further ensures that the initial angle of the rotor is calculated more accurately, and simultaneously the two-phase voltage signal can be converted into the two-phase current signal more accurately according to the voltage conversion relation and the first relation. The specific relationships described above are exemplary only, and any variations fall within the scope of the present application.

In addition, the voltage conversion relation further includes:

t＞t ₀ the first relation further includes:

In another embodiment of the present application, the second conversion unit includes a construction module and a second conversion module, and the construction module is configured to construct a second relation according to the two-phase current signal and the second angle; the second conversion module is configured to adopt the second relation:

In yet another embodiment of the present application, the apparatus further includes a constructing unit and a second determining unit, the constructing unit is configured to construct a third relation based on the two-phase voltage signal, the resistance value, the first inductance, the second inductance, a duration of a high level of the input voltage signal, the first angle, the second angle, and the angle difference; the second determining unit is configured to determine the second angle and the angle difference value by using the third relation and the first current signal on the first coordinate axis of the three-phase coordinate system. In this embodiment, actually, the first angle is a known parameter, the second angle is an unknown parameter, and correspondingly, the angle difference is also an unknown parameter, so that a third relational expression is constructed, the second angle and the angle difference can be accurately determined by using the third relational expression, and then the initial angle of the rotor can be more accurately determined subsequently.

In a specific embodiment of the present application, the second determining unit includes a first determining module, and the first determining module is configured to adopt the third relation:

representing the angular difference. In this embodiment, after the first current signal is analyzed by using the third relational expression, the second angle and the angle difference value may be determined, and since the second angle and the angle difference value are unknown parameters, the third relational expression may be deformed, and the second angle and the angle difference value may be obtained. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

In order to further accurately detect the second angle, in an embodiment of the present application, the apparatus further includes a third determining unit and a first processing unit, the third determining unit is configured to determine whether the first inductance and the second inductance are equal after constructing a third relational expression according to the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference; the first processing unit is used for determining that the second angle detection fails and generating first prompt information under the condition that the first inductance and the second inductance are equal.

In order to further accurately detect the second angle, in another embodiment of the present application, the apparatus further includes a fourth determining unit and a second processing unit, the fourth determining unit is configured to determine whether the duration of the high level of the input voltage signal is greater than a duration threshold of a first predetermined multiple after constructing a third relation according to the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference; the second processing unit is used for determining that the second angle detection fails and generating second prompt information under the condition that the duration time of the high level of the input voltage signal is greater than the duration time threshold of the first preset multiple.

from this formula, the three-phase current can be determinedThe signal is only related to the first angle, and the second angle cannot be determined, so that the duration of the high level of the input voltage signal needs to be ensured to be short.

In another embodiment of the present application, the second angle varies with a variation of the first angle, and when there are a plurality of first angles, there are a plurality of second angles, the three-phase current signals include a first current signal on a first coordinate axis, a second current signal on a second coordinate axis, and a third current signal on a third coordinate axis, the first determining unit includes a second determining module and a third determining module, and the second determining module is configured to determine a maximum first angle from the plurality of first angles based on the first current signal; the third determining module is configured to determine the initial angle of the rotor according to a maximum first angle corresponding to the first current signal, the first angle corresponding to the second current signal, and the first angle corresponding to the third current signal. In this embodiment, the second angle is changed with the change of the first angle, and thus the initial angle of the rotor can be accurately determined by extracting the largest first angle among the first angles. The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

Specifically, let i _A ＝i _A1 +i _A2 ，

Assuming that the axis of the rotor is stationary, it can be seen from the above equations that, when the steady state is not reached, since the first angle is known, the parameters of the plurality of motors are known, i _A1 Approximated by a known quantity, i _A2 Varies with the variation of the first angle, and it can be thus determined that the first angle and the second angle satisfy θ ^* The amplitude collected is maximum at 2 θ. The three-phase current signals are processed, e.g. first current signal minus i _A1 To obtainTo a current containing a second angle, the first current signal only remains i _A2 . The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

In yet another embodiment of the present application, the third determining module includes a first determining submodule, a second determining submodule, and a third determining submodule, the first determining submodule is configured to determine a maximum first angle from a plurality of the first angles based on the second current signal; the second determining submodule is used for determining the maximum first angle from a plurality of first angles based on the third current signal; the third determining submodule is used for performing verification according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to a verification result. In this embodiment, in order to compare the magnitude of the current signal having the second angle and further determine the second angle, the maximum first angle of the first current signal needs to be verified by using the maximum first angle of the second current signal and the maximum first angle of the third current signal, so that it is ensured that the accuracy of the initial angle of the rotor for subsequent detection is higher.

In a specific embodiment of the present application, the third determining sub-module is further configured to determine a checking condition, where the checking condition includes: the maximum first angle corresponding to the second current signal is equal to a first target angle and the maximum first angle corresponding to the third current signal is equal to a second target angle; the third determining submodule is also used for determining that the verification result representation passes the verification under the condition that the verification condition is met; the third determining submodule is further used for determining that the second angle is a second preset multiple of the maximum first angle corresponding to the first current signal under the condition that the verification result represents that the first current signal passes; the third determining submodule is further configured to determine that the initial angle of the rotor is the second angle. In this embodiment, the maximum first angle of the first current signal is further verified, which can ensure a higher accuracy of the detected initial angle of the rotor.

In particular, the amount of the solvent to be used,the first angle at which the first current signal is maximum should be

The second angle should be

The maximum first angle corresponding to the second current signal should be

The maximum second angle corresponding to the third current signal should be

The specific relationships described above are exemplary only, and any variations are within the scope of the present application.

The device for determining the initial angle of the rotor of the permanent magnet synchronous motor comprises a processor and a memory, wherein the acquisition unit, the first conversion unit, the second conversion unit, the first determination unit and the like are stored in the memory as program units, and the processor executes the program units stored in the memory to realize corresponding functions.

The processor comprises a kernel, and the kernel calls the corresponding program unit from the memory. The kernel can be set to one or more than one, and the initial angle of the rotor is accurately determined by adjusting the kernel parameters.

The memory may include volatile memory in a computer readable medium, Random Access Memory (RAM) and/or nonvolatile memory such as Read Only Memory (ROM) or flash memory (flash RAM), and the memory includes at least one memory chip.

An embodiment of the present invention provides a computer-readable storage medium, on which a program is stored, which, when executed by a processor, implements the method for determining an initial angle of a rotor of a permanent magnet synchronous motor described above.

The embodiment of the invention provides a processor, which is used for running a program, wherein the program is run to execute the method for determining the initial angle of the rotor of the permanent magnet synchronous motor.

The application also provides a motor, which comprises a stator, a rotor and a device for determining the initial angle of the rotor, wherein the stator is sleeved on the rotor, the device for determining the initial angle of the rotor is electrically connected with the stator and the rotor respectively, and the device for determining the initial angle of the rotor is used for executing any one of the methods.

The motor firstly obtains two-phase voltage signals, then converts the two-phase voltage signals into two-phase current signals, then converts the two-phase current signals into three-phase current signals, and finally determines the initial angle of the rotor according to the three-phase current signals. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

The embodiment of the invention provides equipment, which comprises a processor, a memory and a program which is stored on the memory and can run on the processor, wherein when the processor executes the program, at least the following steps are realized:

The device herein may be a server, a PC, a PAD, a mobile phone, etc.

The present application further provides a computer program product adapted to perform a program of initializing at least the following method steps when executed on a data processing device:

In order to make the technical solutions of the present application more clearly understood by those skilled in the art, the technical solutions and technical effects of the present application will be described below with reference to specific embodiments.

Examples

The present embodiment relates to a method for determining an initial angle of a rotor of a permanent magnet synchronous motor, as shown in fig. 5, the method includes:

firstly, data acquisition is started, an input voltage signal is injected at an angle of 0 degree, a current signal of a three-phase coordinate system is acquired, a first current signal, a second current signal and a third current signal are acquired, whether the first angle is larger than 360 degrees or not is determined, and the first angle is changed at a fixed step length under the condition that the first angle is not larger than 360 degrees;

under the condition that the first angle is larger than 360 degrees, respectively selecting the largest first angle from the first current signal, the second current signal and the third current signal, calculating a second angle by using the largest amplitude value corresponding to the first current signal, determining whether the largest first angle corresponding to the second current signal is equal to a first target angle or not, and determining whether the largest first angle corresponding to the third current signal is equal to a second target angle or not;

and in the case that the verification passes, determining that the second angle is half of the maximum first angle corresponding to the first current signal.

And finishing the detection.

In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the above-described division of the units may be a logical division, and in actual implementation, there may be another division, for example, multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit may be stored in a computer-readable storage medium if it is implemented in the form of a software functional unit and sold or used as a separate product. Based on such understanding, the technical solution of the present invention, which is substantially or partly contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic disk, or an optical disk, and various media capable of storing program codes.

From the above description, it can be seen that the above-described embodiments of the present application achieve the following technical effects:

1) the method for determining the initial angle of the permanent magnet synchronous motor rotor comprises the steps of firstly obtaining a two-phase voltage signal, then converting the two-phase voltage signal into a two-phase current signal, then converting the two-phase current signal into a three-phase current signal, and finally determining the initial angle of the rotor according to the three-phase current signal. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

2) The device for determining the initial angle of the permanent magnet synchronous motor rotor comprises an acquisition unit, a first conversion unit, a second conversion unit and a first determination unit, wherein the acquisition unit acquires two-phase voltage signals, the first conversion unit converts the two-phase voltage signals into two-phase current signals, the second conversion unit converts the two-phase current signals into three-phase current signals, and the first determination unit determines the initial angle of the rotor according to the three-phase current signals. In this scheme, through the current signal that the direct two-phase voltage signal that surveys the injection produced on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and change to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

3) The motor firstly acquires a two-phase voltage signal, then converts the two-phase voltage signal into a two-phase current signal, then converts the two-phase current signal into a three-phase current signal, and finally determines the initial angle of the rotor according to the three-phase current signal. In this scheme, adopt through the direct current signal that looks into the two-phase voltage signal that injects and produce on the three-phase coordinate system and confirm the rotor position, compare and need further pass through the multiple conversion with three-phase current signal among the prior art and then shift to two-phase coordinate current signal again and just can estimate the rotor position signal, this scheme need not more conversion process, can guarantee that the sampling point is comparatively accurate, and then the degree of accuracy of the initial angle of the rotor that detects is higher, and the calculated amount is less relatively. Meanwhile, the scheme does not relate to the process of multiple conversion in the prior art, so that the calculation process of the scheme is simpler than that in the prior art.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for determining an initial angle of a rotor of a permanent magnet synchronous motor, comprising:

acquiring a two-phase voltage signal, wherein the two-phase voltage signal is obtained by performing two-phase representation on an input voltage signal, and the input voltage signal is a voltage signal input to a stator of a permanent magnet synchronous motor to be detected;

converting the two-phase voltage signal into a two-phase current signal;

converting the two-phase current signals into three-phase current signals, wherein the three-phase current signals are represented by a three-phase coordinate system, three coordinate axes in the three-phase coordinate system are coplanar, an included angle between any two coordinate axes is larger than 0 degrees, and the directions of any two coordinate axes are different;

and determining the initial angle of the rotor according to the three-phase current signals.

2. The method of claim 1, wherein converting the two-phase voltage signal to a two-phase current signal comprises:

obtaining a resistance value of a resistor in the stator, a first inductance on a d-axis of a two-phase coordinate system, a second inductance on a q-axis of the two-phase coordinate system, a duration of a high level of the input voltage signal, a target duration, a first angle, a second angle, and an angle difference value, where the first angle is a target included angle before the input voltage signal is input to the stator, the second angle is the target included angle after the input voltage signal is input to the stator, the angle difference value is a difference value between the first angle and the second angle, the target included angle is an included angle between the d-axis of the two-phase coordinate system and a d-axis of a standard coordinate system, a direction of the d-axis of the two-phase coordinate system is a direction from an S pole to an N pole of a winding of the stator, and the q-axis of the two-phase coordinate system is perpendicular to the d-axis of the two-phase coordinate system, the direction of the d axis of the standard coordinate system is parallel to the transverse symmetrical axis of the stator, and the q axis of the standard coordinate system is perpendicular to the d axis of the standard coordinate system;

and constructing a first relational expression according to the input voltage signal, the resistance value, the first inductor, the second inductor, the duration of the high level of the input voltage signal, the target time length and the angle difference value, and converting the two-phase voltage signal into a two-phase current signal by at least adopting the first relational expression.

3. The method of claim 2, wherein converting the two-phase voltage signal to a two-phase current signal using at least the first relationship comprises:

constructing a voltage conversion relation:

wherein u is _d Representing the voltage component, u, of the two-phase voltage signal on the d-axis of the two-phase coordinate system _q Representing a voltage component, U, of said two-phase voltage signal on the q-axis of said two-phase coordinate system _m Representing the input voltage signal, t representing the duration of the high level of the input voltage signal, t ₀ Representing the target duration;

using the first relationship:

and the voltage conversion relation converts the two-phase voltage signal into the two-phase current signal, wherein i _d Representing a current component, i, of the two-phase current signal on a d-axis of the two-phase coordinate system _q Represents a current component of the two-phase current signal on a q-axis of the two-phase coordinate system, R represents the resistance value,

represents the angular difference, L _d Representing said first inductance, L _q Representing the second inductance.

4. The method of claim 3, wherein converting the two-phase current signal to a three-phase current signal comprises:

constructing a second relation based on the two-phase current signal and the second angle;

using the second relationship:

5. The method of claim 2, further comprising:

constructing a third relation according to the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference;

and determining the second angle and the angle difference value by adopting the third relation and the first current signal on the first coordinate axis of the three-phase coordinate system.

6. The method of claim 5, wherein determining the second angle and the angle difference using the third relationship and the first current signal on the first coordinate axis of the three-phase coordinate system comprises:

using the third relationship:

and the firstThe current signal determines the second angle and the angle difference, where i _A Representing said first current signal, U _m A voltage signal representing the d-axis of the input voltage signal in the two-phase coordinate system, R represents the resistance value, and L represents _d Representing said first inductance, L _q Representing the second inductance, t representing the duration of the high level of the input voltage signal, θ ^* Represents the first angle, theta represents the second angle,

representing the angular difference.

7. The method of claim 5, wherein after constructing a third relationship based on the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference, the method further comprises:

determining whether the first inductance and the second inductance are equal;

and under the condition that the first inductance and the second inductance are equal, determining that the second angle detection fails, and generating first prompt information.

8. The method of claim 5, wherein after constructing a third relationship based on the two-phase voltage signal, the resistance value, the first inductance, the second inductance, the duration of the high level of the input voltage signal, the first angle, the second angle, and the angle difference, the method further comprises:

determining whether a duration of a high level of the input voltage signal is greater than a first predetermined multiple of a duration threshold;

and under the condition that the duration of the high level of the input voltage signal is greater than the duration threshold of the first preset multiple, determining that the second angle detection fails, and generating second prompt information.

9. The method of claim 2, wherein the second angle varies with a variation of the first angle, and in a case where there are a plurality of the first angles, the second angle is also plural, and the three-phase current signals include a first current signal on a first coordinate axis, a second current signal on a second coordinate axis, and a third current signal on a third coordinate axis, and determining an initial angle of the rotor based on the three-phase current signals includes:

determining a maximum first angle from a plurality of the first angles based on the first current signal;

and determining the initial angle of the rotor according to the maximum first angle corresponding to the first current signal, the first angle corresponding to the second current signal and the first angle corresponding to the third current signal.

10. The method of claim 9, wherein determining the initial angle of the rotor according to the maximum first angle for the first current signal, the first angle for the second current signal, and the first angle for the third current signal comprises:

determining a maximum first angle from a plurality of the first angles based on the second current signal;

determining a maximum first angle from a plurality of the first angles based on the third current signal;

and checking according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to a checking result.

11. The method of claim 10, wherein checking according to the maximum first angle corresponding to the second current signal and the maximum first angle corresponding to the third current signal, and determining the initial angle of the rotor according to the checking result comprises:

determining a verification condition, wherein the verification condition comprises: the maximum first angle corresponding to the second current signal is equal to a first target angle and the maximum first angle corresponding to the third current signal is equal to a second target angle;

determining that the verification result representation passes verification under the condition that the verification condition is met;

determining that the second angle is a second predetermined multiple of a maximum first angle corresponding to the first current signal under the condition that the verification result representation passes;

determining the initial angle of the rotor to be the second angle.

12. An apparatus for determining an initial angle of a rotor of a permanent magnet synchronous motor, comprising:

the device comprises an acquisition unit, a detection unit and a control unit, wherein the acquisition unit is used for acquiring a two-phase voltage signal, the two-phase voltage signal is obtained by performing two-phase representation on an input voltage signal, and the input voltage signal is a voltage signal input to a stator of the permanent magnet synchronous motor to be detected;

a first conversion unit for converting the two-phase voltage signal into a two-phase current signal;

the second conversion unit is used for converting the two-phase current signals into three-phase current signals, wherein a three-phase coordinate system is adopted to represent the three-phase current signals, three coordinate axes in the three-phase coordinate system are coplanar, an included angle between any two coordinate axes is larger than 0 degree, and the directions of any two coordinate axes are different;

and the first determining unit is used for determining the initial angle of the rotor according to the three-phase current signals.

13. An electric machine, comprising: initial angle determination means for a stator, a rotor and a rotor, said stator being mounted on said rotor, said initial angle determination means for said rotor being electrically connected to said stator and said rotor, respectively, said initial angle determination means for said rotor being adapted to perform the method of any one of claims 1 to 11.