Open-phase detection method, open-phase detection system, compressor, and refrigeration device

Abstract

The application discloses a phase loss detection method, a phase loss detection system, a compressor and a refrigeration device. The phase loss detection method comprises the following steps: dividing the running time of a predetermined position stage into several time periods in sequence; detecting the three-phase current of a rotor in each time period and analyzing whether each phase has a phase loss risk; if a certain phase has a phase loss risk in at least two time periods, it is determined that the phase has a phase loss fault; after the predetermined position stage ends, entering a stable running stage, estimating the increment of the rotor position angle in each control period Ts, comparing the increment with a set boundary value, and making further analysis according to the comparison detection result. Different phase loss detection logics are adopted in the predetermined position stage and the stable running stage, the reliability of phase loss detection is effectively improved, single-phase phase loss can be detected, and two-phase phase loss or three-phase phase loss can also be detected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, in particular to a phase failure detection method, a phase failure detection system, a compressor and a refrigeration device. BACKGROUND

[0002] The phase failure of the three-phase motor used by the compressor refers to that a phase or multiple phases of the three-phase connection of the motor are in poor contact or open circuit, resulting in that the motor cannot operate normally. If a phase is in phase failure, the current of the phase is zero, and the currents of the other two phases increase rapidly, and the currents of the windings of the non-open phase increase rapidly, and the three-phase currents are unbalanced or too large.

[0003] At present, in the control of the permanent magnet synchronous motor of the compressor, the position angle of the rotor is an indispensable necessary variable. Due to the limitation of the structure and working environment of the compressor, it is difficult to install a mechanical position sensor, so a sensorless algorithm is widely used. However, since the sensorless control algorithm based on back electromotive force detection cannot estimate the position of the rotor when the motor is at rest, a rotor pre-positioning method is needed to determine the position of the rotor when the motor is at rest. The rotor pre-positioning refers to a method of dragging the rotor to a set position to realize rotor pre-positioning by sequentially generating a plurality of current vectors with fixed size and adjustable direction in the stator of the permanent magnet synchronous motor, and using the electromagnetic torque generated by the interaction of the stator winding current and the rotor. This results in a large difference in the properties of the rotor current in the pre-positioning and stable operation stages. If the same phase failure detection logic is used in the pre-positioning and stable operation stages, the reliability is not high, and false positives are easily caused.

[0004] For example, a motor phase failure detection method based on current balance detection is disclosed in the prior art. The method compares the actual current value with the reference current value at several pre-set current detection points to determine whether a phase exists phase failure. This detection method does not take into account the unbalanced characteristics of the three-phase current in the rotor pre-positioning stage, and the discrete sampling method of the current is also prone to false positives.

[0005] Therefore, how to design a phase failure detection method that can detect accurately and calculate simply is a technical problem to be solved in the industry. SUMMARY

[0006] In order to solve the defect that the existing detection method is prone to false positives, the present application proposes a phase failure detection method, a phase failure detection system, a compressor and a refrigeration device, which can improve the reliability of phase failure detection and can detect single-phase phase failure, two-phase phase failure or three-phase phase failure.

[0007] The technical scheme adopted by the present application is to design a phase failure detection method, comprising:

[0008] The running time of the pre-positioning stage is divided into several time periods in sequence;

[0009] In each time period, the three-phase current of the rotor is detected and it is analyzed whether each phase has the risk of open-phase, if a phase has the risk of open-phase in at least two time periods, it is determined that the phase has the open-phase fault.

[0010] Further, the open-phase risk analysis method of the pre-positioning stage is:

[0011] The three-phase current of the rotor is continuously detected in the current time period;

[0012] The sum of the absolute values of the detected three-phase current is calculated;

[0013] The single-phase current open-phase risk threshold is determined according to the sum of the absolute values of the three-phase current;

[0014] If the current of a phase is less than the single-phase current open-phase risk threshold and remains for a corresponding set time t, it is determined that the phase has the risk of open-phase in the current time period;

[0015] Wherein, 0 < t < the length of the current time period.

[0016] In some embodiments, when a phase has been determined to have the risk of open-phase in the previous time period and is determined to have the risk of open-phase again in any time period after the time period, it is determined that the phase has the open-phase fault.

[0017] Further, the open-phase detection method further comprises:

[0018] After the pre-positioning stage ends, entering the stable running stage;

[0019] Estimating the increment Δθ of the rotor position angle θ in each control period Ts;

[0020] When the increment Δθ is greater than a set boundary value, it is determined whether any phase of the three-phase current of the rotor has been determined to have the risk of open-phase, if not, the open-phase risk count and the open-phase fault count of the phase are both cleared, if yes, the open-phase fault count of the phase is incremented;

[0021] And / or when the increment Δθ is not greater than the set boundary value, the three-phase current of the rotor is detected and it is analyzed whether each phase has the risk of open-phase, if yes, the open-phase risk count of the phase is incremented.

[0022] Further, after the open-phase fault count of the phase is incremented, it is determined whether the open-phase fault count reaches a set fault count threshold, if yes, it is determined that the phase has the open-phase fault, if not, it is returned to re-estimate the increment Δθ.

[0023] Further, after the phase risk count of the phase is incremented, it is determined whether the phase risk count reaches a set risk count threshold, if yes, it is determined that the phase has a risk of open phase, if no, it returns to re-estimate the increment Δθ.

[0024] Further, the open phase risk analysis mode of the stable running stage is:

[0025] continuously detecting the three-phase currents of the rotor;

[0026] calculating the sum of the absolute values of the detected three-phase currents;

[0027] determining a single-phase current open phase risk threshold according to the sum of the absolute values of the three-phase currents;

[0028] if the current of a certain phase is less than the single-phase current open phase risk threshold for a continuous rotation of the rotor by a set angle θ1, it is determined that the phase has a risk of open phase.

[0029] Further, the open phase detection method further comprises: determining whether at least one phase has an open phase fault, if yes, executing a shutdown protection, and clearing all counts.

[0030] In some embodiments, the single-phase current open phase risk threshold is 1 / 4 of the sum of the absolute values of the three-phase currents.

[0031] The present application also proposes an open phase detection system, comprising:

[0032] a sampling module which collects the three-phase currents of the rotor in a predetermined positioning stage and / or a stable running stage;

[0033] a calculation module which receives the three-phase currents fed back by the sampling module and calculates a single-phase current open phase risk threshold;

[0034] a logical judgment module which divides the running time of the predetermined positioning stage into several time periods in a front-back order, analyzes whether each phase has a risk of open phase according to the three-phase currents and the single-phase current open phase risk threshold in each time period, and determines that a certain phase has an open phase fault when the phase has a risk of open phase in at least two time periods.

[0035] Further, the open phase detection system further comprises: a rotor position angle estimation module which estimates the increment Δθ of the rotor position angle θ in each control period Ts; and the logical judgment module receives the three-phase currents of the rotor and the increment Δθ in the stable running stage.

[0036] when the increment Δθ is greater than a set boundary value, the logical judgment module determines whether a certain phase of the three-phase currents of the rotor has been determined to have a risk of open phase, if no, the open phase risk count and the open phase fault count of the phase are cleared, if yes, the open phase fault count of the phase is incremented;

[0037] And / or when the increment Δθ is not greater than a set boundary value, the logic judging module analyzes whether there is a risk of phase loss in each phase according to the three-phase current, and if yes, the phase loss risk count of the phase is incremented.

[0038] The application further provides a compressor, comprising a motor, wherein the motor is subjected to phase loss detection by using the phase loss detection method.

[0039] The application further provides a refrigeration device, which has the compressor.

[0040] Compared with the prior art, the application has the following beneficial effects:

[0041] 1. The phase loss detection method is designed according to the current characteristics of the rotor in the pre-positioning stage, and the corresponding phase loss detection logic is used to divide the pre-positioning stage into several time periods, detect the three-phase current of the rotor in each time period, and determine that a phase has a phase loss fault if the phase has a risk of phase loss in at least two time periods.

[0042] 2. The increment of the rotor position angle is introduced to assist the phase loss fault detection in the stable running stage, the increment Δθ of the rotor position angle θ in each control period Ts is estimated, Δθ is compared with a set boundary value, and further analysis is made according to the comparison result to improve the reliability of the phase loss detection. BRIEF DESCRIPTION OF DRAWINGS

[0043] The application will be described in detail below with reference to the embodiments and the accompanying drawings.

[0044] Figure 1 Fig. 1 is a flowchart of the phase loss detection method of the application;

[0045] Figure 2 Fig. 2 is a module diagram of the phase loss detection system of the application. DETAILED DESCRIPTION

[0046] In order to make the technical problems, technical solutions and beneficial effects of the application clearer, the application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0047] The phase absence detection method is suitable for a three-phase motor, which is commonly used in a compressor. The inventor finds that after the motor is powered on, it enters a pre-positioning stage, and the rotor pre-positioning method is used to align the rotor magnetic field with the stator coil magnetic field. The current in the stator coil is often asymmetric, and the current value of a certain phase may even be set to zero at some time. Therefore, during the pre-positioning stage, i.e., the power-on stage of the three-phase motor, the method of detecting whether the current value of a certain phase is zero cannot be used to detect the phase absence of the motor.

[0048] Based on the above research, the inventor designs the corresponding phase absence detection logic according to the current characteristics of the rotor in the pre-positioning stage. The running time of the pre-positioning stage is divided into several time periods. The three-phase current of the rotor is continuously detected in each time period, and whether there is a risk of phase absence in each phase is analyzed. If there is a risk of phase absence in a certain phase in at least two time periods, it is determined that there is a phase absence fault in the phase, so as to improve the accuracy of phase absence detection.

[0049] It should be understood that the "running time of the pre-positioning stage" mentioned above can be obtained by experiment statistics in advance, and "several" means more than two. For example, the running time of the pre-positioning stage is divided into N time periods in the order of front and back. After the motor is powered on, as the working time increases, it enters the second time period from the first time period, and then enters the fourth time period from the third time period, and so on. After passing through each time period in turn, it finally enters the Nth time period. After the end of the Nth time period, the motor enters the stable running stage. In actual application, the running time of the pre-positioning stage can be divided into time periods with the same or different time lengths, which is designed according to specific use requirements, and the present application does not specially limit it.

[0050] In some embodiments, the phase absence risk analysis method in the pre-positioning stage is as follows:

[0051] The three-phase current of the rotor is continuously detected in the current time period;

[0052] The sum of the absolute values of the detected three-phase currents is calculated;

[0053] A single-phase current phase absence risk threshold is determined according to the sum of the absolute values of the three-phase currents;

[0054] If the current of a certain phase is less than the single-phase current phase absence risk threshold and remains for a corresponding set time t, it is determined that there is a risk of phase absence in the current time period.

[0055] It should be noted that 0 < t < the length of the current period, the smaller the value of t, the easier it is to determine the risk of single-phase failure, the set time t of each period can be different, of course, if the length of each period is the same, the set time t of each period can also be the same. In addition, the way to determine the single-phase current single-phase failure risk threshold based on the sum of the three-phase current absolute values can be to take a certain proportion of the sum of the three-phase current absolute values as the single-phase current single-phase failure risk threshold, that is, single-phase current single-phase failure risk threshold = sum of three-phase current absolute values × proportion coefficient, the proportion coefficient should be less than 1 / 3, in a specific application example of the application, 1 / 4 of the sum of the three-phase current absolute values is taken as the single-phase current single-phase failure risk threshold.

[0056] In fact, since the periods of the pre-positioning stage are in sequence, when a phase has been determined to have a single-phase failure risk in the previous period and is determined to have a single-phase failure risk again in any period after the period, the condition of having a single-phase failure risk in at least two periods is met, so the phase is directly determined to have a single-phase failure, and it is not necessary to continue the single-phase failure risk judgment of the next period. That is, in the pre-positioning stage, when any phase is determined to have a single-phase failure risk for the second time, the phase is directly determined to have a single-phase failure, and the shutdown protection is executed.

[0057] In some embodiments of the application, the inventors design corresponding single-phase detection logic for the rotor operating characteristics of the stable operation stage, introduce an incremental auxiliary single-phase failure detection of the rotor position angle, estimate the increment Δθ of the rotor position angle θ in each control period Ts, compare Δθ with a set boundary value, and make further analysis according to the comparison detection result to improve the reliability of single-phase detection.

[0058] Specifically, the single-phase detection method further comprises:

[0059] After the pre-positioning stage ends, the motor starts and starts to accelerate, enters the stable operation stage of medium and high speed, and the motor operates at this speed. The rotor position angle can be stably estimated by the detected motor back electromotive force. The back electromotive force observer is designed as follows:

[0060]

[0061]

[0062] In the formula, u αβ is the input control voltage of the motor, i αβ is obtained by coordinate transformation of the three-phase current, l s is the stator inductance, R s is the stator resistance, e αβ is the back electromotive force, θ is the rotor position angle, ω r is the rotor angular velocity, and ψ fTo estimate the rotor position angle θ.

[0063] The above formula is rewritten as an incremental formula, i.e. the increment Δθ of the position angle θ is obtained:

[0064]

[0065]

[0066] According to the above formula, the increment Δθ of the rotor position angle θ in each control period Ts is estimated;

[0067] When the increment Δθ is greater than the set boundary value, it indicates that the change of the rotor position angle θ is relatively large, and on this basis, it is determined whether a phase of the three-phase current of the rotor has been judged to have a risk of open-phase, to determine whether the phase is faulty. If a phase has not been judged to have a risk of open-phase before, it indicates that the increment Δθ of the position angle of the phase is within a normal range, and the open-phase risk count and the open-phase fault count of the phase are both cleared. If a phase has been judged to have a risk of open-phase before, it indicates that the increment Δθ of the position angle of the phase is abnormal, and the open-phase fault count of the phase is incremented.

[0068] When the increment Δθ is not greater than the set boundary value, it indicates that the increment Δθ of the rotor position angle is small under the current control period, and there is a possibility of open-phase fault. On this basis, the three-phase current of the rotor is detected to analyze whether each phase has a risk of open-phase. If the current of a phase has a risk of open-phase, the open-phase risk count of the phase is incremented.

[0069] It should be noted that the set boundary value refers to the maximum value of Δθ in a control period Ts, which can be obtained by experimental statistics. The increment refers to automatically adding one to the current count. The above open-phase detection method is continuously performed in the stable running stage, and the open-phase fault count of each phase of the three-phase current is counted separately. After the open-phase fault count of any phase is incremented, it is determined whether the open-phase fault count reaches a set fault count threshold. If yes, it is determined that the phase has an open-phase fault. If no, the increment Δθ is re-estimated. After the open-phase risk count of any phase is incremented, it is determined whether the open-phase risk count reaches a set risk count threshold. If yes, it is determined that the phase has a risk of open-phase. If no, the increment Δθ is re-estimated.

[0070] In order to protect the motor in time, the open-phase detection method further includes: judging in real time whether at least one phase has an open-phase fault. If yes, a shutdown protection is performed, and all counts are cleared. That is, in the predetermined position stage and the stable running stage, as long as a phase current is judged to have an open-phase fault, the motor will perform a shutdown protection, and subsequent detection and judgment actions are stopped, and the open-phase risk count and the open-phase fault count are cleared.

[0071] In some embodiments proposed by the present invention, the phase loss risk analysis method during the stable operation phase is as follows:

[0072] Continuously detect the three-phase current of the rotor;

[0073] Calculate the sum of the absolute values ​​of the three-phase currents detected;

[0074] Determine the single-phase current loss risk threshold based on the sum of the absolute values ​​of the three-phase currents;

[0075] If the current of a certain phase remains less than the single-phase current phase loss risk threshold within the time when the rotor continuously rotates the set angle θ1, it is determined that there is a phase loss risk in this phase.

[0076] It should be noted that during the stable operation phase, the time for the rotor to continuously rotate through a set angle θ1 is used as the holding time to improve the accuracy of phase loss judgment. This is because during the stable operation phase, the change in current is closely related to the rotation of the rotor, and the rotor position angle θ can be estimated in real time. If the current of a phase remains less than the single-phase current phase loss risk threshold during the time the rotor continuously rotates through the set angle θ1, it indicates that during the rotor rotation process, the phase current is too low during the time the rotor rotates through the angle θ1, and there is a phase loss risk. Of course, in actual applications, the time for continuous rotation through the set angle θ1 can also be directly designed as the set holding time, and the present invention does not impose any special restrictions on this.

[0077] In addition, the method of determining the single-phase current phase loss risk threshold based on the sum of the absolute values ​​of the three-phase currents can be to take a certain proportion of the value based on the sum of the absolute values ​​of the three-phase currents as the single-phase current phase loss risk threshold, that is, the single-phase current phase loss risk threshold = the sum of the absolute values ​​of the three-phase currents × the proportional coefficient, the proportional coefficient should be lower than 1 / 3. In a specific application example of the present invention, 1 / 4 of the sum of the absolute values ​​of the three-phase currents is taken as the single-phase current phase loss risk threshold.

[0078] like Figure 1 As shown, in a specific application example of the present invention, the running time of the pre-positioning stage is divided into two periods of equal length, the single-phase current phase loss risk threshold is 1 / 4 of the sum of the absolute values ​​of the three-phase currents, and the time t is set to 1 / 4 of the running time of the pre-positioning stage. The process of the phase loss control method is as follows.

[0079] Step S1, start phase failure detection;

[0080] Step S2, determining whether the motor is in the pre-positioning stage, if so, proceeding to step S3, if not, proceeding to step S10;

[0081] Step S3, calculating 1 / 4 of the sum of the absolute values ​​of the three-phase currents;

[0082] Step S4, it is judged whether or not it is in the first half of the predetermined position phase, if yes, step S5 is performed, if not, step S7 is performed;

[0083] Step S5, it is judged whether or not there is a phase current less than 1 / 4 of the sum of the absolute values of the three-phase currents and the operation time of the predetermined position phase is maintained for 1 / 4, if yes, step S6 is performed;

[0084] Step S6, it is judged that there is a risk of phase loss in the phase;

[0085] Step S7, it is in the second half of the predetermined position phase;

[0086] Step S8, it is judged whether or not there is a phase current less than 1 / 4 of the sum of the absolute values of the three-phase currents and the operation time of the predetermined position phase is maintained for 1 / 4, if yes, step S9 is performed;

[0087] Step S9, it is judged that there is a phase loss in the phase, step S22 is performed;

[0088] Step S10, the increment Δθ of the rotor position angle θ in each control period Ts is estimated;

[0089] Step S11, it is judged whether or not the increment Δθ is greater than a set boundary value, if yes, step S12 is performed, if not, step S18 is performed;

[0090] Step S12, it is judged whether or not there is a phase in which the phase loss risk has been judged in the three-phase currents of the rotor, if yes, step S13 is performed, if not, step S15 is performed;

[0091] Step S13, the phase loss risk count of the phase is cleared;

[0092] Step S14, the phase loss fault count of the phase is cleared, step S22 is performed;

[0093] Step S15, the phase loss fault count of the phase is incremented;

[0094] Step S16, it is judged whether or not the phase loss fault count reaches a set fault count threshold, if yes, step S17 is performed;

[0095] Step S17, it is judged that there is a phase loss in the phase, step S22 is performed;

[0096] Step S18, it is judged whether or not there is a phase current less than 1 / 4 of the sum of the absolute values of the three-phase currents and the time in which the rotor continuously rotates by a set angle θ1 is maintained, if yes, step S19 is performed;

[0097] Step S19, the phase loss risk count of the phase is incremented;

[0098] Step S20, judging whether the open-phase risk count reaches a set risk count threshold, if yes, proceeding to step S21;

[0099] Step S21, judging whether the phase exists open-phase risk;

[0100] Step S22, judging whether at least one phase exists open-phase fault in the three phases, if yes, proceeding to step S23;

[0101] Step S23, executing shutdown protection, and clearing all counts.

[0102] As shown in the figure, the present application further provides an open-phase detection system, comprising: Figure 2 a sampling module, which collects the three-phase currents of the rotor in the predetermined positioning phase and / or the stable operation phase;

[0103] a calculation module, which receives the three-phase currents fed back by the sampling module and calculates the open-phase risk threshold of the single-phase current;

[0104] a logical judgment module, which divides the operation time of the predetermined positioning phase into several time periods in the order of before and after, analyzes whether each phase exists open-phase risk according to the three-phase currents and the open-phase risk threshold of the single-phase current in each time period, and judges that the phase exists open-phase fault when the phase exists open-phase risk in at least two time periods.

[0105] In some embodiments, the open-phase detection system further comprises a rotor position angle estimation module, which estimates the increment Δθ of the rotor position angle θ in each control period Ts; and the logical judgment module receives the three-phase currents of the rotor and the increment Δθ in the stable operation phase.

[0106] When the increment Δθ is greater than a set boundary value, the logical judgment module judges whether any phase of the three-phase currents of the rotor has been judged to exist open-phase risk, if not, the open-phase risk count and the open-phase fault count of the phase are both cleared, and if yes, the open-phase fault count of the phase is incremented.

[0107] When the increment Δθ is not greater than the set boundary value, the logical judgment module analyzes whether each phase exists open-phase risk according to the three-phase currents, and if yes, the open-phase risk count of the phase is incremented.

[0108] It should be noted that the open-phase risk count and the open-phase fault count are both counted by the counter, and the open-phase detection logic executed by the logical judgment module is the same as the flow of the open-phase detection method in the above, which is not described here. In order to make the staff discover the open-phase fault of the motor as soon as possible, the open-phase detection system sends an alarm signal to the outside while executing the shutdown protection.

[0109]

[0110] ​The phase deficiency detection method can be applied to a compressor, and the compressor uses the phase deficiency detection method to detect phase deficiency of a motor.

[0111] The application further provides a refrigeration device having the compressor, and the refrigeration device includes but is not limited to a refrigerator and the like.

[0112] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0113] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in these embodiments are not meant to limit the scope of the present application unless otherwise specifically stated. It is also to be understood that the use of relational terms such as "first", "second", "third", and the like, if any, are used solely to distinguish one from another entity or action without necessarily implying a serial or chronological order, unless clearly stated otherwise. The technical, methodological and instrumental details known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of the example embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0114] The above descriptions are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A phase loss detection method, characterized in that: Comprising: Dividing the running time of the pre-positioning stage into several time periods in sequence; Detecting the three-phase current of the rotor in each time period and analyzing whether there is a risk of phase loss in each phase. If there is a risk of phase loss in a certain phase in at least two time periods, it is determined that there is a phase loss fault in this phase; Entering the stable operation stage after the end of the pre-positioning stage; Estimating the increment Δθ of the rotor position angle θ within each control cycle Ts; When the increment Δθ is greater than the set boundary value, determining whether there is a certain phase in the three-phase current of the rotor that has been determined to have a risk of phase loss. If not, both the phase loss risk count and the phase loss fault count of this phase are cleared. If so, the phase loss fault count of this phase is incremented; When the increment Δθ is not greater than the set boundary value, detecting the three-phase current of the rotor and analyzing whether there is a risk of phase loss in each phase. If so, the phase loss risk count of this phase is incremented; 2. The phase loss detection method according to claim 1, characterized in that: The method for analyzing the risk of phase loss in the pre-positioning stage is as follows: Continuously detecting the three-phase current of the rotor in the current time period; Calculating the sum of the absolute values of the detected three-phase currents; Determining the single-phase current phase loss risk threshold according to the sum of the absolute values of the three-phase currents; If the current of a certain phase is less than the single-phase current phase loss risk threshold and remains for the corresponding set time t, it is determined that there is a risk of phase loss in this phase in the current time period; Where, 0 < t < the duration of the current time period.

3. The phase loss detection method according to claim 1, characterized in that: When a certain phase has been determined to have a risk of phase loss in the previous time period and is determined to have a risk of phase loss again in any time period after this time period, it is determined that there is a phase loss fault in this phase.

4. The phase loss detection method according to claim 1, characterized in that: After the phase loss fault count of this phase is incremented, determining whether the phase loss fault count reaches the set fault count threshold. If so, it is determined that there is a phase loss fault in this phase. If not, return to re-estimate the increment Δθ; 5. The phase loss detection method according to claim 1, characterized in that: After the phase loss risk count of this phase is incremented, determining whether the phase loss risk count reaches the set risk count threshold. If so, it is determined that there is a risk of phase loss in this phase. If not, return to re-estimate the increment Δθ; 6. The phase loss detection method according to claim 1, characterized in that: The method for analyzing the risk of phase loss in the stable operation stage is as follows: Continuously detecting the three-phase current of the rotor; Calculating the sum of the absolute values of the detected three-phase currents; Determining the single-phase current phase loss risk threshold according to the sum of the absolute values of the three-phase currents; If the current of a certain phase remains less than the single-phase current phase loss risk threshold within the time when the rotor continuously rotates a set angle θ1, it is determined that there is a risk of phase loss in this phase.

7. The phase loss detection method according to any one of claims 1 to 6, characterized in that: It further comprises: Judging whether there is at least one phase with a phase loss fault. If so, performing shutdown protection and clearing all counts; 8. The phase loss detection method according to claim 6, characterized in that: The single-phase current phase loss risk threshold is 1 / 4 of the sum of the absolute values of the three-phase currents; 9. Phase loss detection system, characterized in that, Comprising: A sampling module, which samples the three-phase current of the rotor in the pre-positioning stage and / or the stable operation stage; A calculation module, which receives the three-phase current fed back by the sampling module and calculates the single-phase current phase loss risk threshold; A logic judgment module, which divides the running time of the pre-positioning stage into several time periods in sequence, analyzes whether there is a risk of phase loss in each phase according to the three-phase current and the single-phase current phase loss risk threshold in each time period, and when a certain phase has a risk of phase loss in at least two time periods, determines that there is a phase loss fault in this phase; a rotor position angle estimation module, which estimates an increment Δθ of the rotor position angle θ within each control period Ts; the logic judgment module receives the three-phase current of the rotor and the increment Δθ during the stable operation phase; When the increment Δθ is greater than a set boundary value, the logic judgment module determines whether a phase in the three-phase current of the rotor has been determined to have a phase loss risk. If not, the phase loss risk count and phase loss fault count of the phase are reset to zero. If so, the phase loss fault count of the phase is automatically incremented. When the increment Δθ is not greater than the set boundary value, the logic judgment module analyzes whether there is a phase loss risk for each phase based on the three-phase current. If so, the phase loss risk count of the phase is automatically incremented.

10. Compressor, including: The motor is characterized in that the compressor adopts the phase loss detection method described in any one of claims 1 to 8 to perform phase loss detection on the motor.

11. Refrigeration equipment, characterized in that The refrigeration device comprises the compressor according to claim 10.

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