CN112034338B

CN112034338B - Phase current open circuit diagnosis method and device for electric power steering motor

Info

Publication number: CN112034338B
Application number: CN201910406370.8A
Authority: CN
Inventors: 郑冬霞; 苏阳; 刘飞; 张成宝; 邓念; 刘咏萱; 陈远龙; 林龙贤; 韩东冬; 徐灯福; 李勇
Original assignee: SAIC Motor Corp Ltd
Current assignee: SAIC Motor Corp Ltd
Priority date: 2019-05-16
Filing date: 2019-05-16
Publication date: 2023-06-20
Anticipated expiration: 2039-05-16
Also published as: CN112034338A

Abstract

The embodiment of the application discloses a diagnosis method for open circuit of EPS motor phase current, which can determine to perform low-speed open circuit diagnosis or high-speed open circuit diagnosis according to the relation between the motor rotating speed and the threshold rotating speed. When the low-speed circuit breaking diagnosis is carried out, as the phase relation between the motor electrical angle and each phase of current of the motor is fixed, one phase or multiple phases of current in a non-zero-crossing interval can be determined according to the acquired motor electrical angle, and then the low-speed circuit breaking diagnosis mode is started for the phase or multiple phases of current, so that the diagnosis of the phase current in the zero-crossing interval is avoided, the situation of misdiagnosis caused by too small current in the zero-crossing interval is avoided, and the phase current circuit breaking diagnosis of the EPS motor current can be accurately carried out even under the condition of low rotating speed of the EPS motor.

Description

Phase current open circuit diagnosis method and device for electric power steering motor

Technical Field

The application relates to the field of motor diagnosis, in particular to a method and a device for diagnosing phase current breaking of an electric power steering motor.

Background

The electric power steering (Electric Power Steering, EPS) is to directly provide steering power for the automobile by a motor, so that a power steering oil pump, a hose, hydraulic oil, a conveyor belt and a belt pulley arranged on an engine which are necessary for a hydraulic power steering system are omitted, energy is saved, pollution to the environment is avoided, and the electric power steering is an important development direction of the current automobile steering system.

The motor directly provides steering assistance for the automobile, the current of the EPS motor under all working conditions needs to be diagnosed, when the diagnosis finds that the phase current of the EPS motor is broken, the working state of the EPS motor needs to be adjusted timely, so that steering abnormality caused by the abnormal operation of the EPS motor is avoided, and in the running process of the automobile, the steering abnormality brings great safety risks to drivers and passengers on the automobile.

However, when the rotational speed of the EPS motor is low, the corresponding EPS motor phase current frequency is low, and the phase current zero-crossing time is long, so that there is a high possibility that the motor phase current is broken due to the fact that the motor phase current change is small and does not reach the monitoring threshold value in the fault confirmation time. In order to prevent the occurrence of the above-mentioned misdiagnosis, the conventional art generally does not start the phase current interruption diagnosis when the rotation speed of the EPS motor is low. However, the diagnosis of the phase current of the motor under all working conditions cannot be realized, and certain potential safety hazards may exist in the running process of the automobile.

Disclosure of Invention

In order to solve the technical problem, the application provides an EPS motor phase current open circuit diagnosis method which is used for carrying out open circuit diagnosis on the EPS motor phase current under the full working condition, and even if the EPS motor rotating speed is lower, the EPS motor phase current can be ensured to be accurately subjected to open circuit diagnosis.

The embodiment of the application discloses the following technical scheme:

in a first aspect, embodiments of the present application provide a method for diagnosing phase current interruption of an electric power steering motor, the method including:

acquiring motor working information, wherein the motor working information comprises: the motor speed, the motor electrical angle, the motor first phase current, the motor second phase current and the motor third phase current;

judging whether the motor rotating speed is smaller than a threshold rotating speed or not;

if the motor rotating speed is smaller than the threshold rotating speed, judging whether the motor electrical angle is in a non-zero crossing region of the motor first phase current, if yes, starting a low-speed circuit breaking diagnosis mode of the motor first phase current; judging whether the electric angle of the motor is in a non-zero crossing region of the second phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the second phase current of the motor; judging whether the electric angle of the motor is in a non-zero crossing region of the third phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the third phase current of the motor;

and if the motor rotating speed is greater than or equal to the threshold rotating speed, respectively starting a high-speed circuit breaking diagnosis mode of the motor first phase current, the motor second phase current and the motor third phase current.

Optionally, the low-speed circuit breaking diagnosis mode for starting the first phase current of the motor includes:

judging whether the first phase current of the motor is smaller than a low-speed single-phase current preset value, if so, adding a first preset value to a low-speed error confirmation value corresponding to the first phase current of the motor, and if so, subtracting a second preset value from the low-speed error confirmation value corresponding to the first phase current of the motor;

judging whether a low-speed error confirmation value corresponding to the motor first phase current is larger than a low-speed error threshold value, and if so, judging that the motor first phase current is disconnected;

the low-speed circuit breaking diagnosis mode for starting the second phase current of the motor comprises the following steps:

judging whether the second phase current of the motor is smaller than the low-speed single-phase current preset value, if so, adding the first preset value to the low-speed error confirmation value corresponding to the second phase current of the motor, and if so, subtracting the second preset value from the low-speed error confirmation value corresponding to the second phase current of the motor;

judging whether a low-speed error confirmation value corresponding to the motor second phase current is larger than the low-speed error threshold value, and if so, judging that the motor second phase current is broken;

The low-speed circuit breaking diagnosis mode for starting the third phase current of the motor comprises the following steps:

judging whether the third phase current of the motor is smaller than the low-speed single-phase current preset value, if so, adding the first preset value to the low-speed error confirmation value corresponding to the third phase current of the motor, and if so, subtracting the second preset value from the low-speed error confirmation value corresponding to the third phase current of the motor;

and judging whether a low-speed error confirmation value corresponding to the motor third-phase current is larger than the low-speed error threshold value, and if so, judging that the motor third-phase current is broken.

Optionally, the high-speed circuit breaking diagnosis mode for respectively turning on the motor first phase current, the motor second phase current and the motor third phase current includes:

judging whether the first phase current of the motor is smaller than a high-speed single-phase current preset value, if so, adding a third preset value to a high-speed error confirmation value corresponding to the first phase current of the motor, and if so, subtracting a fourth preset value from the high-speed error confirmation value corresponding to the first phase current of the motor;

judging whether a high-speed error confirmation value corresponding to the motor first phase current is larger than a high-speed error threshold value, and if so, judging that the motor first phase current is disconnected;

Judging whether the second phase current of the motor is smaller than the high-speed single-phase current preset value, if so, adding the third preset value to the high-speed error confirmation value corresponding to the second phase current of the motor, and if so, subtracting the fourth preset value from the high-speed error confirmation value corresponding to the second phase current of the motor;

judging whether a high-speed error confirmation value corresponding to the second phase current of the motor is larger than the high-speed error threshold value, and if so, judging that the second phase current of the motor is broken;

judging whether the third phase current of the motor is smaller than the preset value of the high-speed single-phase current, if so, adding the third preset value to the high-speed error confirmation value corresponding to the third phase current of the motor, and if so, subtracting the fourth preset value from the high-speed error confirmation value corresponding to the third phase current of the motor;

judging whether the high-speed error confirmation value corresponding to the motor third-phase current is larger than the high-speed error threshold value, and if so, judging that the motor third-phase current is broken.

Optionally, the high-speed error confirmation value corresponding to the first phase current of the motor, the high-speed error confirmation value corresponding to the second phase current of the motor and the high-speed error confirmation value corresponding to the third phase current of the motor are all proportional to the proximity degree of the high-speed fault confirmation time.

Optionally, the high-speed fault confirmation time is greater than one third of the electrical period corresponding to the threshold rotation speed.

Optionally, the non-zero crossing interval of the first phase current of the motor is an interval including an electrical angle corresponding to a peak value of the first phase current of the motor;

the non-zero crossing interval of the motor second phase current is an interval comprising an electrical angle corresponding to the motor second phase current peak value;

the non-zero crossing interval of the motor third phase current is an interval comprising an electrical angle corresponding to the motor third phase current peak value.

Optionally, the threshold rotation speed is less than the initial field weakening rotation speed of the motor.

Optionally, the motor operation information further includes: the current target torque of the motor and the root mean square of dq axis current;

the method further includes, prior to determining whether the motor speed is less than a threshold speed:

judging whether the root mean square of the dq axis current is smaller than the calibratable current or not;

if the dq axis current root mean square is smaller than the calibratable current, judging whether the current target torque of the motor is larger than a threshold torque, and if so, adding a fifth preset value to the multiphase open circuit error confirmation value;

judging whether the multiphase disconnection error confirmation value is larger than a multiphase disconnection error threshold value, and if so, judging that the multiphase current of the motor is disconnected;

And if the dq axis current root mean square is larger than the calibratable current, subtracting a sixth preset value from the multiphase disconnection error confirmation value.

In a second aspect, embodiments of the present application provide an electric power steering motor phase current interruption diagnostic apparatus, the apparatus comprising:

the acquisition module is used for acquiring motor working information, and the motor working information comprises: the motor speed, the motor electrical angle, the motor first phase current, the motor second phase current and the motor third phase current;

the judging module is used for judging whether the motor rotating speed is smaller than a threshold rotating speed or not;

the low-speed circuit breaking diagnosis module is used for judging whether the electric angle of the motor is in a non-zero crossing region of the first phase current of the motor if the rotating speed of the motor is smaller than the threshold rotating speed, and if so, starting a low-speed circuit breaking diagnosis mode of the first phase current of the motor; judging whether the electric angle of the motor is in a non-zero crossing region of the second phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the second phase current of the motor; judging whether the electric angle of the motor is in a non-zero crossing region of the third phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the third phase current of the motor;

And the high-speed circuit breaking diagnosis module is used for respectively starting a high-speed circuit breaking diagnosis mode of the motor first phase current, the motor second phase current and the motor third phase current if the motor rotating speed is greater than or equal to the threshold rotating speed.

Optionally, the low-speed circuit breaker diagnosis module includes:

the first low-speed circuit breaking diagnosis unit is used for judging whether the first phase current of the motor is smaller than a low-speed single-phase current preset value, if so, adding a first preset value to a low-speed error confirmation value corresponding to the first phase current of the motor, and if so, subtracting a second preset value from the low-speed error confirmation value corresponding to the first phase current of the motor; judging whether a low-speed error confirmation value corresponding to the motor first phase current is larger than a low-speed error threshold value, and if so, judging that the motor first phase current is disconnected;

the second low-speed circuit breaker diagnosis unit is used for judging whether the second phase current of the motor is smaller than the low-speed single-phase current preset value, if so, adding the first preset value to the low-speed error confirmation value corresponding to the second phase current of the motor, and if so, subtracting the second preset value from the low-speed error confirmation value corresponding to the second phase current of the motor; judging whether a low-speed error confirmation value corresponding to the motor second phase current is larger than the low-speed error threshold value, and if so, judging that the motor second phase current is broken;

The third low-speed circuit breaking diagnosis unit is used for judging whether the third-phase current of the motor is smaller than the low-speed single-phase current preset value, if so, the first preset value is added to the low-speed error confirmation value corresponding to the third-phase current of the motor, and if so, the second preset value is subtracted from the low-speed error confirmation value corresponding to the third-phase current of the motor; and judging whether a low-speed error confirmation value corresponding to the motor third-phase current is larger than the low-speed error threshold value, and if so, judging that the motor third-phase current is broken.

Optionally, the high-speed circuit breaker diagnosis module includes:

the first high-speed circuit breaking diagnosis unit is used for judging whether the first phase current of the motor is smaller than a high-speed single-phase current preset value, if so, adding a third preset value to a high-speed error confirmation value corresponding to the first phase current of the motor, and if so, subtracting a fourth preset value from the high-speed error confirmation value corresponding to the first phase current of the motor; judging whether a high-speed error confirmation value corresponding to the motor first phase current is larger than a high-speed error threshold value, and if so, judging that the motor first phase current is disconnected;

the second high-speed circuit breaking diagnosis unit is used for judging whether the second phase current of the motor is smaller than the high-speed single-phase current preset value, if so, adding the third preset value to the high-speed error confirmation value corresponding to the second phase current of the motor, and if so, subtracting the fourth preset value from the high-speed error confirmation value corresponding to the second phase current of the motor; judging whether a high-speed error confirmation value corresponding to the second phase current of the motor is larger than the high-speed error threshold value, and if so, judging that the second phase current of the motor is broken;

A third high-speed circuit breaking diagnosis unit, configured to determine whether the third phase current of the motor is less than the high-speed single-phase current preset value, if so, add the third preset value to a high-speed error confirmation value corresponding to the third phase current of the motor, and if so, subtract the fourth preset value to a high-speed error confirmation value corresponding to the third phase current of the motor; judging whether the high-speed error confirmation value corresponding to the motor third-phase current is larger than the high-speed error threshold value, and if so, judging that the motor third-phase current is broken.

the apparatus further comprises: a multi-phase disconnection diagnosis unit;

the multiphase circuit breaking diagnosis unit is used for judging whether the root mean square of the dq axis current is smaller than the calibratable current;

According to the technical scheme, the EPS motor phase current circuit breaking diagnosis method can determine to conduct low-speed circuit breaking diagnosis or high-speed circuit breaking diagnosis according to the relation between the motor rotating speed and the threshold rotating speed. When the low-speed circuit breaking diagnosis is carried out, as the phase relation between the motor electrical angle and each phase of current of the motor is fixed, one phase or multiple phases of current in a non-zero-crossing interval can be determined according to the acquired motor electrical angle, and then the low-speed circuit breaking diagnosis mode is started for the phase or multiple phases of current, so that the diagnosis of the phase current in the zero-crossing interval is avoided, the situation of misdiagnosis caused by too small current in the zero-crossing interval is avoided, and the phase current circuit breaking diagnosis of the EPS motor current can be accurately carried out even under the condition of low rotating speed of the EPS motor.

In addition, the diagnosis method for the open circuit of the phase current of the EPS motor, provided by the application, determines the diagnosed phase current according to the motor electrical angle under the condition that the rotation speed of the EPS motor is low, and respectively diagnoses the phase currents of the motor under the condition that the rotation speed of the EPS motor is high. That is, the EPS motor phase current open circuit diagnosis method provided by the present application does not perform open circuit diagnosis according to the overall voltage or current signal output by the EPS motor, but performs open circuit diagnosis according to the diagnosis result of each phase current, so that the fault phase where current open circuit occurs can be accurately located.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive faculty for a person skilled in the art.

Fig. 1 is a schematic circuit diagram of an EPS motor driving system according to an embodiment of the present application;

fig. 2 is a schematic flow chart of a method for diagnosing open circuit of phase current of an EPS motor according to an embodiment of the present application;

fig. 3 is a schematic flow chart of another EPS motor phase current interruption diagnostic method according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of an EPS motor phase current interruption diagnostic apparatus according to an embodiment of the present application.

Detailed Description

Embodiments of the present application are described below with reference to the accompanying drawings.

The motor directly provides steering assistance for the automobile, the full-working-condition EPS motor current needs to be subjected to circuit breaking diagnosis, and when the diagnosis finds that the EPS motor current is abnormal, the working state of the motor is timely adjusted and/or fault prompt is carried out, so that the automobile steering abnormality caused by the EPS motor current abnormality is prevented, and safety risks are brought to drivers and passengers on the automobile.

The conventional methods for diagnosing the open circuit of the phase current of the EPS motor are two, and the two methods for diagnosing the open circuit of the phase current of the EPS motor are described below:

the first method is to collect a synthesized voltage signal in a pulse form generated when the EPS motor works, pass the synthesized voltage signal through a low-pass filter with a cut-off frequency lower than the PWM carrier frequency to set the synthesized voltage signal into sine wave voltage, further calculate current corresponding to the sine wave voltage according to an EPS motor voltage equation and EPS motor parameters, compare the current with a preset current threshold, and judge whether the phase current of the EPS motor is broken or not according to a comparison result.

In the second method, current signals in a sine wave form generated when the EPS motor works are collected, the sine wave current signals are converted into direct current voltage signals through Park coordinate conversion and Clark coordinate conversion, then current corresponding to the direct current voltage signals is calculated according to an EPS motor voltage equation and EPS motor parameters under a rotating coordinate system, the current is compared with a preset current threshold, and whether the phase current of the EPS motor is broken or not is judged according to a comparison result.

The inventor researches and discovers that the two traditional methods are adopted to carry out the phase current breaking diagnosis of the EPS motor, and the phase current breaking diagnosis is not started under the condition that the rotating speed of the EPS motor is low. The reason for this is that when the EPS motor is low in rotation speed, the frequency of each phase current is low, and the zero-crossing time of each phase current is long, so that the probability that the phase current collected in the fault confirmation time is the phase current in the zero-crossing interval is high, and the current value of the phase current in the zero-crossing interval is generally low and cannot reach the monitoring threshold value, so that when the EPS motor is low in rotation speed, the probability that the motor phase current is broken due to misdiagnosis is high. In order to thoroughly prevent such misdiagnosis, the conventional phase current shutdown diagnostic method generally does not start the phase current shutdown diagnostic mode in the case of a low rotational speed of the EPS motor.

However, without opening the phase current circuit breaking diagnosis mode under the condition that the rotation speed of the EPS motor is low, real-time diagnosis of the phase current under all working conditions of the EPS motor cannot be achieved, and the motor working state is adjusted and/or early warning prompt is carried out according to the diagnosis result.

In order to solve the problems, the application provides a method for diagnosing the open circuit of the phase current of an EPS motor, which can carry out the open circuit diagnosis on the phase current of the EPS motor under the full working condition, and can ensure the accurate open circuit diagnosis on the phase current of the EPS motor even if the rotating speed of the EPS motor is lower.

The EPS motor phase current circuit breaking diagnosis method comprises the steps of firstly obtaining motor working information such as motor rotating speed, motor electric angle, motor phase currents and the like; judging whether the collected motor rotating speed is smaller than a threshold rotating speed, and if the motor rotating speed is smaller than the threshold rotating speed, performing low-speed circuit breaking diagnosis: judging whether the acquired motor electric angle is in a non-zero crossing interval of each phase of current of the motor, and if the motor electric angle is in a non-zero crossing interval corresponding to any phase or multi-phase current in the three-phase current, starting a low-speed circuit breaking diagnosis mode aiming at the phase or multi-phase current; if the motor rotation speed is greater than the threshold rotation speed, performing high-speed circuit breaking diagnosis: the high-speed circuit breaking diagnosis mode is directly started for the current of each phase of the motor.

Therefore, the EPS motor phase current circuit breaking diagnosis method can determine to perform low-speed circuit breaking diagnosis or high-speed circuit breaking diagnosis according to the relation between the motor rotating speed and the threshold rotating speed. When the low-speed circuit breaking diagnosis is carried out, as the motor electric angle and the motor phase currents have the association relation, one phase or multiple phases of current in a non-zero-crossing interval can be determined according to the acquired motor electric angle, and then the low-speed circuit breaking diagnosis mode is started for the phase or multiple phases of current, so that the diagnosis for the phase current in the zero-crossing interval is avoided, the situation of misdiagnosis caused by too small current in the zero-crossing interval is avoided, and the phase current circuit breaking diagnosis for the EPS motor current can be accurately carried out even under the condition of low rotating speed of the EPS motor.

It should be understood that the EPS motor phase current interruption diagnosis method provided in the present application is applied to an EPS motor driving system, referring to fig. 1, fig. 1 is a schematic circuit diagram of the EPS motor driving system provided in the present application. The motor driving system includes an EPS motor 101, a microcontroller (Microcontroller Unit, MCU) 102, a driving circuit 103, a motor rotation angle detector 104, and a phase current sensor 105. The MCU102 has functions of data processing, fault recognition and motor control, and can execute the EPS motor phase current open circuit diagnosis method provided in the present application, so as to perform open circuit diagnosis on the EPS motor phase current according to motor working information collected by each component in the EPS motor driving system.

The following describes, in an embodiment, a method for diagnosing open circuit of phase current of an EPS motor provided in the present application:

referring to fig. 2, fig. 2 is a flow chart of a method for diagnosing open circuit of phase current of an EPS motor according to the present embodiment, where the method includes:

step 201: acquiring motor working information, wherein the motor working information comprises: motor speed, motor electrical angle, motor first phase current, motor second phase current, and motor third phase current.

Each sensor in the EPS motor driving system acquires motor working information, and the MCU processes the motor working information acquired by each sensor to acquire motor working information comprising motor rotating speed, motor electric angle, motor first phase current, motor second phase current, motor third phase current and the like.

Step 202: and judging whether the motor rotating speed is smaller than a threshold rotating speed or not.

Judging whether the motor rotation speed obtained in the step 201 is smaller than a threshold rotation speed, wherein the threshold rotation speed is a demarcation point for performing low-speed circuit breaking diagnosis and high-speed circuit breaking diagnosis, and performing low-speed circuit breaking diagnosis when the motor rotation speed is smaller than the threshold rotation speed, namely executing the step 203; when the motor speed is greater than or equal to the threshold speed, a high speed trip diagnosis is performed, i.e., step 204 is performed.

Step 203: if the motor rotating speed is smaller than the threshold rotating speed, judging whether the motor electrical angle is in a non-zero crossing region of the motor first phase current, if yes, starting a low-speed circuit breaking diagnosis mode of the motor first phase current; judging whether the electric angle of the motor is in a non-zero crossing region of the second phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the second phase current of the motor; and judging whether the electric angle of the motor is in a non-zero crossing region of the third phase current of the motor, and if so, starting a low-speed circuit breaking diagnosis mode of the third phase current of the motor.

And when the motor rotating speed is smaller than the threshold rotating speed, correspondingly performing low-speed circuit breaking diagnosis: since the phase relationship between the motor electrical angle and the motor phase currents is fixed, according to the motor electrical angle obtained in step 201, one or more phase currents currently in a non-zero crossing region can be determined, and then a low-speed circuit breaker diagnosis mode is started for the one or more phase currents. Therefore, the diagnosis of the phase current in the zero crossing region is avoided when the rotating speed of the EPS motor is low, and the situation of misdiagnosis caused by too small phase current in the zero crossing region is avoided.

When the motor is in the zero-crossing interval, the motor first phase current is larger when the EPS motor works normally, and the motor first phase current has a reference value for judging the open circuit of the phase current. Thus, when the motor electrical angle is in a non-zero crossing of the motor first phase current, a low speed circuit breaker diagnostic mode of the motor first phase current is enabled.

Similarly, when the electric angle of the motor is in the non-zero crossing interval of the second phase current of the motor, the second phase current value of the motor is indicated to have a reference value for judging the open circuit of the phase current, so that the low-speed open circuit diagnosis mode of the second phase current of the motor can be started at the moment; when the motor electrical angle is in the non-zero crossing of the motor third phase current, it is stated that the motor third phase current value has a reference value for determining that the phase current is open, and therefore, the low-speed open-circuit diagnostic mode of the motor third phase current can be turned on at this time.

It should be noted that, the above non-zero crossing interval of the first phase current of the motor, the non-zero crossing interval of the second phase current of the motor, and the non-zero crossing interval of the third phase current of the motor may be set according to practical situations, and two methods for determining the non-zero crossing interval of each phase current of the motor are described below:

The first method can preset the interval length of the non-zero crossing interval of each phase of current of the motor, takes the electric angle corresponding to the peak value of the first phase of current of the motor as the midpoint of the non-zero crossing interval of the first phase of current of the motor, and further determines the non-zero crossing interval of the first phase of current of the motor; taking an electric angle corresponding to the peak value of the second phase current of the motor as the midpoint of the non-zero crossing interval of the second phase current of the motor, and further determining the non-zero crossing interval of the second phase current of the motor; and taking the electric angle corresponding to the peak value of the third-phase current of the motor as the midpoint of the non-zero-crossing interval of the third-phase current of the motor, and further determining the non-zero-crossing interval of the third-phase current of the motor.

For example, the interval length of the non-zero crossing interval of the current of each phase of the motor is preset to be pi/3, the motor electrical angles corresponding to the current peak value of the first phase of the motor are pi/2 and 3 pi/2 respectively, pi/2 and 3 pi/2 are respectively taken as the midpoints of the non-zero crossing intervals of the current of the first phase of the motor, and then the non-zero crossing intervals of the current of the first phase of the motor are [ pi/3, 2 pi/3) and [4 pi/3, 5 pi/3 respectively); the electric angles of the motor corresponding to the peak value of the second phase current of the motor are pi/6 and 7 pi/6 respectively, pi/6 and 7 pi/6 are respectively taken as the midpoints of the non-zero crossing intervals of the second phase current of the motor, and then the non-zero crossing intervals of the second phase current of the motor are [0, pi/3) and [ pi, 4 pi/3 respectively); the motor electric angles corresponding to the motor third phase current peak values are 5 pi/6 and 11 pi/6 respectively, and the 5 pi/6 and the 11 pi/6 are respectively taken as the midpoints of the non-zero crossing intervals of the motor third phase current, so that the non-zero crossing intervals of the motor third phase current are [2 pi/3, pi) and [5 pi/3, 2 pi) respectively.

In the second method, a current threshold may be preset, an electrical angle interval in which an absolute value of a first phase current of the motor is greater than the current threshold is taken as a non-zero-crossing interval of the first phase current of the motor, an electrical angle interval in which an absolute value of a second phase current of the motor is greater than the current threshold is taken as a non-zero-crossing interval of the second phase current of the motor, and an electrical angle interval in which an absolute value of a third phase current of the motor is greater than the current threshold is taken as a non-zero-crossing interval of the third phase current of the motor.

Of course, other methods of setting the non-zero crossing of the motor phase currents may be used, and the method of setting the non-zero crossing of the motor phase currents is not limited.

In order to simplify calculation in the motor phase current open circuit diagnosis process, improve accuracy of motor phase current open circuit diagnosis, when low-speed open circuit diagnosis is carried out on each phase current of a motor, whether each phase current of the motor is open circuit during low-speed operation of the EPS motor can be judged according to the low-speed error confirmation value corresponding to each phase current of the motor by a method of accumulating or decrementing a corresponding preset value for the low-speed error confirmation value corresponding to each phase current of the motor.

When the electric angle of the motor is in a non-zero crossing interval of the first phase current of the motor, the low-speed circuit breaking diagnosis of the first phase current of the motor is carried out: and judging whether the first phase current of the motor is smaller than a low-speed single-phase current preset value, if so, adding a first preset value to a low-speed error confirmation value corresponding to the first phase current of the motor, and if so, subtracting a second preset value from the low-speed error confirmation value corresponding to the first phase current of the motor. And further, judging whether the low-speed error confirmation value corresponding to the motor first phase current is larger than a low-speed error threshold value, if so, indicating that the motor first phase current is possibly judged to be smaller than a low-speed single-phase current preset value for many times, and the possibility of the motor first phase current breaking is very high, so that the motor first phase current breaking is judged, and correspondingly, the motor first phase current can be adjusted and/or prompt and early warning can be carried out.

Similarly, when the motor electrical angle is in a non-zero crossing of the motor second phase current, a low speed circuit breaking diagnostic mode of the motor second phase current is turned on: and judging whether the second phase current of the motor is smaller than a low-speed single-phase current preset value, if so, adding a first preset value to a low-speed error confirmation value corresponding to the second phase current of the motor, and if so, subtracting the second preset value from the low-speed error confirmation value corresponding to the second phase current of the motor. And judging whether the low-speed error confirmation value corresponding to the second-phase current of the motor is larger than the low-speed error threshold value, if so, judging that the second-phase current of the motor is broken, and correspondingly adjusting and/or prompting and early warning the second-phase current of the motor.

Similarly, when the motor electrical angle is in a non-zero crossing of the motor third phase current, a low speed circuit breaking diagnostic mode of the motor third phase current is started: and judging whether the third phase current of the motor is smaller than a low-speed single-phase current preset value, if so, adding a first preset value to a low-speed error confirmation value corresponding to the third phase current of the motor, and if so, subtracting a second preset value from the low-speed error confirmation value corresponding to the third phase current of the motor. And judging whether the low-speed error confirmation value corresponding to the third-phase current of the motor is larger than the low-speed error threshold value, if so, judging that the second-phase current of the motor is broken, and correspondingly adjusting and/or prompting and early warning the third-phase current of the motor.

The low-speed single-phase current preset value may be set according to actual conditions, and the low-speed single-phase preset value is not specifically limited. The first preset value and the second preset value may also be set according to actual conditions, and no specific limitation is made to the first preset value and the second preset value.

It should be noted that, the low-speed circuit breaking diagnosis may be repeatedly executed in response to a command triggered by a user, and in each diagnosis process, the motor phase current to be diagnosed needs to be determined according to the motor electrical angle, and then according to the comparison result of the diagnosed motor phase current and the low-speed single-phase current preset value, the corresponding preset value is added or subtracted to the low-speed error confirmation value corresponding to each phase current of the motor, and then, according to the low-speed error confirmation value corresponding to each phase current of the motor in the current diagnosis process, whether the motor phase current is broken or not is determined. When the next low-speed circuit breaking diagnosis is carried out, the low-speed circuit breaking error confirmation value corresponding to each phase current of the motor obtained in the last diagnosis process is required to be used as the initial value of the low-speed circuit breaking error confirmation value corresponding to each phase current of the motor in the current low-speed circuit breaking diagnosis process, namely, in the next low-speed circuit breaking diagnosis process, the low-speed error confirmation value corresponding to each phase current of the motor obtained in the last diagnosis process is used as a basis, and the corresponding preset value is added or subtracted according to the comparison result of each phase current of the motor and the low-speed single-phase current preset value.

According to the low-speed circuit breaking diagnosis method, according to a comparison result between each phase current of the motor and a low-speed single-phase current preset value, a corresponding preset value is added or subtracted to a low-speed error confirmation value corresponding to each phase current, and whether each phase current is broken or not is judged according to the low-speed error confirmation value corresponding to each phase current. The method simplifies the calculated amount when the motor phase current is subjected to the open circuit diagnosis to a certain extent, and improves the accuracy of the open circuit diagnosis of the phase current.

Of course, other phase current breaking diagnosis methods may be adopted, and when the motor runs at low speed, the phase current breaking diagnosis is performed on each phase current of the motor, and the low-speed breaking diagnosis method is not limited.

Step 204: and if the motor rotating speed is larger than the threshold rotating speed, respectively starting a high-speed circuit breaking diagnosis mode of the motor first phase current, the motor second phase current and the motor third phase current.

And when the motor rotating speed is greater than the threshold rotating speed, correspondingly performing high-speed circuit breaking diagnosis. When the high-speed circuit breaking diagnosis is carried out, because the zero crossing interval of the current of each phase of the motor is short, the probability of measuring the current of each phase in the zero crossing interval is low in fault phase confirmation time, and therefore, the phase current to be diagnosed is not required to be determined according to the electric angle of the motor, and the high-speed circuit breaking diagnosis mode is directly started for the current of the first phase of the motor, the current of the second phase of the motor and the current of the third phase of the motor.

When the high-speed circuit breaking diagnosis is carried out on the current of each phase of the motor, the diagnosis method similar to the low-speed circuit breaking diagnosis can be adopted for carrying out the high-speed circuit breaking diagnosis on the current of each phase of the motor, and according to the comparison result of the current of each phase of the motor and the preset value of the high-speed single-phase current, the corresponding preset value is added or subtracted to the high-speed error confirmation value corresponding to the current of each phase of the motor, and then whether the current of each phase of the motor is broken or not is judged according to the high-speed error confirmation value corresponding to the current of each phase of the motor.

When the method is specifically implemented, whether the first phase current of the motor is smaller than a high-speed single-phase current preset value can be judged, if so, a third preset value is added to a high-speed error confirmation value corresponding to the first phase current of the motor, and if so, a fourth preset value is subtracted from the high-speed error confirmation value corresponding to the first phase current of the motor. And judging whether the high-speed error confirmation value corresponding to the first phase current of the motor is larger than a high-speed error threshold value, if so, judging that the first phase current of the motor is broken, and further making corresponding adjustment measures and/or carrying out early warning prompt on the first phase current of the motor.

Similarly, when the high-speed circuit breaking diagnosis is carried out on the second phase current of the motor, judging whether the second phase current of the motor is smaller than a high-speed single-phase current preset value, if so, adding a third preset value to a high-speed error confirmation value corresponding to the second phase current of the motor, and if so, subtracting a fourth preset value from the high-speed error confirmation value corresponding to the second phase current of the motor. And judging whether the high-speed error confirmation value corresponding to the second-phase current of the motor is larger than a high-speed error threshold value, if so, judging that the second-phase current of the motor is broken, and further carrying out corresponding adjustment measures and/or early warning prompt on the second-phase current of the motor.

Similarly, when the high-speed circuit breaking diagnosis is carried out on the third phase current of the motor, judging whether the third phase current of the motor is smaller than a high-speed single-phase current preset value, if so, adding the third preset value to a high-speed error confirmation value corresponding to the third phase current of the motor, and if so, subtracting the fourth preset value from the high-speed error confirmation value corresponding to the third phase current of the motor. And judging whether the high-speed error confirmation value corresponding to the third-phase current of the motor is larger than a high-speed error threshold value, if so, judging that the third-phase current of the motor is broken, and further making corresponding adjustment measures and/or carrying out early warning prompt on the third-phase current of the motor.

The high-speed single-phase current preset value may be set according to actual needs, and the method for determining the high-speed single-phase preset value is not limited. The third preset value and the fourth preset value may be set according to actual needs, and the determination method of the third preset value and the fourth preset value is not set.

The order of performing the high-speed circuit breaking diagnosis on the motor first phase current, the motor second phase current and the motor third phase current is not fixed, the motor first phase current, the motor second phase current and the motor third phase current can be simultaneously subjected to the high-speed circuit breaking diagnosis, and the motor first phase current, the motor second phase current and the motor third phase current can be sequentially diagnosed according to the sequence, so that the high-speed circuit breaking diagnosis order is not limited.

It should be noted that, the high-speed circuit breaking diagnosis can be repeatedly executed in response to the instruction triggered by the user, and in each diagnosis process, the corresponding preset value is added or subtracted to the high-speed error confirmation value corresponding to each phase current of the motor according to the comparison result between each phase current of the motor and the preset value of the high-speed single-phase current, so as to determine whether the circuit breaking occurs to each phase current of the motor according to the high-speed error confirmation value corresponding to each phase current of the motor in the current diagnosis process. When the next high-speed circuit breaking diagnosis is carried out, the high-speed circuit breaking error confirmation value corresponding to each phase current of the motor obtained in the last diagnosis process is required to be used as the initial value of the high-speed circuit breaking error confirmation value corresponding to each phase current of the motor in the current high-speed circuit breaking diagnosis process, namely, in the next high-speed circuit breaking diagnosis process, the high-speed error confirmation value corresponding to each phase current of the motor obtained in the last diagnosis process is used as a basis, and the corresponding preset value is added or subtracted according to the comparison result of each phase current of the motor and the high-speed single-phase current preset value.

According to the high-speed circuit breaking diagnosis method, according to the comparison result between each phase current of the motor and the high-speed single-phase current preset value, the corresponding preset value is added or subtracted to the high-speed error confirmation value corresponding to each phase current, and then whether each phase current is broken or not is judged according to the high-speed error confirmation value corresponding to each phase current. The method simplifies the calculated amount when the motor phase current is subjected to the open circuit diagnosis to a certain extent, and improves the accuracy of the open circuit diagnosis of the phase current.

Of course, other phase current breaking diagnosis methods may be adopted, and when the motor operates at high speed, the phase current breaking diagnosis is performed on each phase current of the motor, and the high-speed breaking diagnosis method is not limited.

In addition, the high-speed error confirmation value corresponding to the first phase current of the motor, the high-speed error confirmation value corresponding to the second phase current of the motor and the high-speed error confirmation value corresponding to the third phase current of the motor are proportional to the approaching degree of the high-speed fault confirmation time, and the higher the high-speed error confirmation value corresponding to each phase current of the motor is, the closer the high-speed fault confirmation time is, the high-speed error confirmation value reaches the high-speed error threshold value, namely the high-speed fault confirmation time is reached.

In order to ensure that whether the motor phase currents are broken or not can be more accurately diagnosed in the high-speed breaking diagnosis mode, zero-crossing intervals of the motor phase currents need to be avoided as much as possible when the high-speed breaking diagnosis is performed. The motor electrical angle interval in which the absolute value of each phase current of the motor is smaller than one half of the peak value of each phase current is generally determined as a zero crossing interval, and in one period of the motor phase current, the motor electrical angle interval in which the absolute value of the phase current is larger than one half of the peak value of the phase current accounts for two thirds, and the electrical angle interval corresponding to the phase current in which the absolute value of the phase current is smaller than one half of the peak value of the phase current accounts for one third, namely, the interval length of the non-zero crossing interval is twice the interval length of the zero crossing interval. Therefore, in order to ensure that the current collected in the high-speed diagnostic mode is not entirely the current in the zero-crossing region, it is necessary to ensure that the current sampling frequency is greater than 2 times the phase current frequency, and accordingly, the high-speed fault phase verification time is required to be greater than one third of the electrical period corresponding to the threshold rotation speed.

It should be noted that, in order to prevent the phase relationship between the motor electrical angle and the motor phase current from being affected by the field weakening after the field weakening is added, the current of the motor phase in the non-zero crossing region cannot be accurately determined according to the motor electrical angle, and the threshold rotation speed is generally set to be less than the initial field weakening rotation speed of the motor.

The EPS motor phase current circuit breaking diagnosis method provided by the application can determine to perform low-speed circuit breaking diagnosis or high-speed circuit breaking diagnosis on each phase current of the motor according to the acquired relation between the motor rotating speed and the threshold rotating speed. When the low-speed circuit breaking diagnosis is carried out, whether the collected motor electric angle is in a non-zero-crossing interval of each phase current of the motor is judged, if the motor electric angle is in the non-zero-crossing interval of any phase or multi-phase motor current, a low-speed circuit breaking diagnosis mode is started for the phase or multi-phase current, so that the diagnosis of the phase current in the zero-crossing interval is avoided, the situation of misdiagnosis caused by too small current in the zero-crossing interval is avoided, and the phase current circuit breaking diagnosis of the EPS motor current can be accurately carried out even if the rotating speed of the EPS motor is low. In addition, the diagnosis method for the open circuit of the phase current of the EPS motor, provided by the application, determines the diagnosed phase current according to the motor electrical angle under the condition that the rotation speed of the EPS motor is low, and respectively diagnoses the phase currents of the motor under the condition that the rotation speed of the EPS motor is high. That is, the EPS motor phase current open circuit diagnosis method provided by the present application does not perform open circuit diagnosis according to the overall voltage or current signal output by the EPS motor, but performs open circuit diagnosis according to the diagnosis result of each phase current, so that the fault phase where current open circuit occurs can be accurately located.

In addition, on the basis of the EPS electric power steering motor phase current breaking diagnosis method, multiphase current breaking diagnosis can be performed before low-speed breaking diagnosis or high-speed breaking diagnosis is performed according to motor rotation speed judgment.

Before the multiphase current breaking diagnosis is carried out, motor working information such as the current target torque of the motor, the root mean square of dq axis current and the like needs to be further acquired. The current target torque of the motor is the torque which is set by the system and is currently required to be reached by the motor; the root mean square of dq-axis current is the current of d-axis and q-axis current, according to the formula:

calculated I _dq 。

And judging whether the root mean square of the dq axis current is smaller than the calibratable current.

If the root mean square of the dq axis current is smaller than the calibratable current, the condition that the whole current of the current EPS motor is smaller and multiphase current break possibly occurs is indicated; otherwise, if the root mean square of the dq axis current is larger than the calibratable current, the current EPS motor has larger overall current and smaller possibility of multiphase current open circuit.

The calibratable current may be set according to the actual situation, and is not specifically limited herein.

If the root mean square of the dq axis current is smaller than the calibratable current, continuing to judge whether the current target torque of the motor is larger than the threshold torque, and if the current target torque of the motor is smaller than the threshold torque, indicating that the current target torque of the motor is smaller than the threshold torque, wherein the current target torque of the motor is smaller than the current target torque of the motor, and correspondingly, the root mean square of the dq axis current is smaller than the threshold torque and is in a normal state; otherwise, if the current target torque of the motor is greater than the threshold torque, the motor set by the system is indicated to have larger torque to be achieved, the current EPS motor is smaller, the current EPS motor is abnormal, multi-phase disconnection can occur, and accordingly, a fifth preset value is added to the multi-phase disconnection error confirmation value.

Judging whether the multi-phase open circuit error confirmation value is larger than a multi-phase open circuit error threshold value, if so, judging that the EPS motor is subjected to multi-phase open circuit, and then correspondingly making adjustment measures and/or carrying out corresponding early warning prompt.

If the root mean square of the dq axis current is larger than the calibratable current, the probability of the occurrence of the multi-phase current disconnection of the EPS motor is smaller, and the sixth preset value is subtracted from the multi-phase disconnection error confirmation value.

The threshold torque may be set according to actual requirements, and the threshold torque is not particularly limited here. The fifth preset value and the sixth preset value may be set according to actual needs, and are not specifically limited herein.

Before judging whether the motor rotation speed is smaller than the threshold rotation speed, judging whether the EPS motor is subjected to multiphase disconnection according to the root mean square of dq shaft current and the current target torque of the motor, judging whether the EPS motor is subjected to multiphase disconnection in advance before judging whether the motor is subjected to multiphase disconnection or not, and when judging that the EPS motor is subjected to multiphase current disconnection, correspondingly, not continuing to carry out subsequent judgment, directly adjusting and/or carrying out early warning prompt aiming at the multiphase current disconnection, so that the workload of a system is reduced to a certain extent.

In order to facilitate further understanding of the EPS motor phase current interruption diagnostic method provided in the present application, the following general description of the EPS motor phase current interruption diagnostic method provided in the present application is provided with reference to fig. 3:

step 301: and acquiring motor working information.

The acquired motor operation information includes: motor speed, motor electrical angle, motor first phase current, motor second phase current, motor third phase current, motor current target torque, and dq axis current root mean square.

Step 302: and judging whether the root mean square of the dq axis current is smaller than the calibratable current.

If the root mean square of the dq axis current is less than the calibratable current, then step 303 is performed; otherwise, the sixth preset value is subtracted from the multi-phase open error confirmation value, and step 304 is performed.

Step 303: a multi-phase open circuit diagnostic mode is entered.

Specifically, judging whether the current target torque of the motor is larger than a threshold torque or not; if the current target torque of the motor is larger than the threshold torque, adding a fifth preset value to the multiphase disconnection error confirmation value; otherwise, if the current target torque of the motor is smaller than the threshold torque, no processing is carried out on the multiphase disconnection error confirmation value.

Step 304: and judging whether the rotating speed of the motor is smaller than a threshold rotating speed.

If the motor speed is less than the threshold speed, then step 305 is performed; otherwise, if the motor speed is greater than the threshold speed, step 306 is performed.

Step 305: a low speed circuit breaking diagnostic mode is entered.

Specifically, whether the electric angle of the motor is in a non-zero crossing interval of each phase current of the motor is judged, if the electric angle of the motor is in the non-zero crossing interval of a certain phase current of the motor, whether the phase current is smaller than a low-speed single-phase current preset value is judged, if the phase current is smaller than the preset value, a first preset value is added to a low-speed error confirmation value corresponding to the phase current of the motor, and if the phase current is larger than the preset value, a second preset value is subtracted from the low-speed error confirmation value corresponding to the phase current of the motor.

Step 306: a high speed circuit breaking diagnostic mode is entered.

Specifically, the high-speed circuit breaking diagnosis mode is directly started for each phase current of the motor, whether each phase current of the motor is smaller than a high-speed single-phase current preset value is judged, if so, a third preset value is added to a high-speed error confirmation value corresponding to the phase current of the motor, and if so, a fourth preset value is subtracted from the high-speed error confirmation value corresponding to the phase current of the motor.

Step 307: and performing open circuit diagnosis according to each error confirmation value.

Specifically, whether the multiphase disconnection error confirmation value is larger than a multiphase disconnection error threshold value or not is judged, and if the multiphase disconnection error confirmation value is larger than the multiphase disconnection error threshold value, the multiphase current disconnection of the EPS motor is judged.

Judging whether the low-speed error confirmation value corresponding to each phase current of the motor is larger than a low-speed error threshold value, and if the low-speed error confirmation value corresponding to a certain phase current of the motor is larger than the low-speed error threshold value, judging that the phase current of the motor is broken.

Judging whether the high-speed error confirmation value corresponding to each phase current of the motor is larger than a high-speed error threshold value, and if the high-speed error confirmation value corresponding to a certain phase current of the motor is larger than the high-speed error threshold value, judging that the phase current of the motor is broken.

The application provides an EPS motor phase current circuit breaking diagnostic apparatus, see fig. 4, fig. 4 is a schematic structural diagram of the EPS motor phase current circuit breaking diagnostic apparatus, the apparatus includes:

the obtaining module 401 is configured to obtain motor operation information, where the motor operation information includes: the motor speed, the motor electrical angle, the motor first phase current, the motor second phase current and the motor third phase current;

a judging module 402, configured to judge whether the motor rotation speed is less than a threshold rotation speed;

a low-speed circuit breaking diagnosis module 403, configured to determine whether the electrical angle of the motor is in a non-zero crossing region of the first phase current of the motor if the rotational speed of the motor is less than the threshold rotational speed, and if yes, turn on a low-speed circuit breaking diagnosis mode of the first phase current of the motor; judging whether the electric angle of the motor is in a non-zero crossing region of the second phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the second phase current of the motor; judging whether the electric angle of the motor is in a non-zero crossing region of the third phase current of the motor, if so, starting a low-speed circuit breaking diagnosis mode of the third phase current of the motor;

The high-speed circuit breaking diagnosis module 404 is configured to respectively turn on a high-speed circuit breaking diagnosis mode of the motor first phase current, the motor second phase current, and the motor third phase current if the motor rotation speed is greater than or equal to the threshold rotation speed.

Optionally, the low-speed circuit breaker diagnosis module includes:

Optionally, the high-speed circuit breaker diagnosis module includes:

the apparatus further comprises: a multi-phase disconnection diagnosis unit;

The EPS motor phase current circuit breaking diagnosis device provided by the application can determine to perform low-speed circuit breaking diagnosis or high-speed circuit breaking diagnosis on each phase current of the motor according to the acquired relation between the motor rotating speed and the threshold rotating speed. When the low-speed circuit breaking diagnosis is carried out, whether the collected motor electric angle is in a non-zero-crossing interval of each phase current of the motor is judged, if the motor electric angle is in the non-zero-crossing interval of any phase or multi-phase motor current, a low-speed circuit breaking diagnosis mode is started for the phase or multi-phase current, so that the diagnosis of the phase current in the zero-crossing interval is avoided, the situation of misdiagnosis caused by too small current in the zero-crossing interval is avoided, and the phase current circuit breaking diagnosis of the EPS motor current can be accurately carried out even if the rotating speed of the EPS motor is low. In addition, the diagnosis method for the open circuit of the phase current of the EPS motor, provided by the application, determines the diagnosed phase current according to the motor electrical angle under the condition that the rotation speed of the EPS motor is low, and respectively diagnoses the phase currents of the motor under the condition that the rotation speed of the EPS motor is high. That is, the EPS motor phase current open circuit diagnosis method provided by the present application does not perform open circuit diagnosis according to the overall voltage or current signal output by the EPS motor, but performs open circuit diagnosis according to the diagnosis result of each phase current, so that the fault phase where current open circuit occurs can be accurately located.

It should be noted that, in the present specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment is mainly described in a different point from other embodiments. In particular, for the apparatus and system embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, with reference to the description of the method embodiments in part. The apparatus and system embodiments described above are merely illustrative, in which elements illustrated as separate elements may or may not be physically separate, and elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.

The foregoing is merely one specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for diagnosing phase current interruption of an electric power steering motor, the method comprising:

if the motor rotating speed is greater than or equal to the threshold rotating speed, respectively starting a high-speed circuit breaking diagnosis mode of the motor first phase current, the motor second phase current and the motor third phase current;

The high-speed circuit breaking diagnosis mode for respectively starting the motor first phase current, the motor second phase current and the motor third phase current comprises the following steps:

Judging whether a high-speed error confirmation value corresponding to the third-phase current of the motor is larger than the high-speed error threshold value, and if so, judging that the third-phase current of the motor is broken;

the high-speed error confirmation value corresponding to the first phase current of the motor, the high-speed error confirmation value corresponding to the second phase current of the motor and the high-speed error confirmation value corresponding to the third phase current of the motor are proportional to the proximity degree of the high-speed fault confirmation time;

the high-speed fault confirmation time is greater than one third of the electrical period corresponding to the threshold rotational speed.

2. The method of claim 1, wherein said turning on a low-speed circuit-breaking diagnostic mode of the motor first phase current comprises:

3. The method of claim 1, wherein the non-zero crossing interval of the motor first phase current is an interval including an electrical angle corresponding to a peak value of the motor first phase current;

4. The method of claim 1, wherein the threshold rotational speed is less than a motor start field weakening rotational speed.

5. The method of claim 1, wherein the motor operation information further comprises: the current target torque of the motor and the root mean square of dq axis current;

6. An electric power steering motor phase current interruption diagnostic device, the device comprising:

The high-speed circuit breaking diagnosis module is used for respectively starting a high-speed circuit breaking diagnosis mode of the motor first phase current, the motor second phase current and the motor third phase current if the motor rotating speed is greater than or equal to the threshold rotating speed;

the high-speed circuit breaking diagnosis module includes:

A third high-speed circuit breaking diagnosis unit, configured to determine whether the third phase current of the motor is less than the high-speed single-phase current preset value, if so, add the third preset value to a high-speed error confirmation value corresponding to the third phase current of the motor, and if so, subtract the fourth preset value to a high-speed error confirmation value corresponding to the third phase current of the motor; judging whether a high-speed error confirmation value corresponding to the third-phase current of the motor is larger than the high-speed error threshold value, and if so, judging that the third-phase current of the motor is broken;

7. The apparatus of claim 6, wherein the low-speed circuit breaker diagnostic module comprises:

8. The apparatus of claim 6, wherein the motor operation information further comprises: the current target torque of the motor and the root mean square of dq axis current;

The apparatus further comprises: a multi-phase disconnection diagnosis unit;