Refrigeration device, detection device for synchronous machine and out-of-step detection method thereof

Abstract

The application provides a refrigeration equipment, a synchronous motor detection device and a step-out detection method thereof. The step-out detection method comprises the following steps: starting the synchronous motor, identifying a running event of the synchronous motor after starting, judging whether the rotor back electromotive force of the synchronous motor is in a normal state when the uniform speed running event of the synchronous motor is identified, recording the current peak value of the synchronous motor in a plurality of continuous preset time intervals respectively under the condition that the rotor back electromotive force of the synchronous motor is in the normal state, and determining that the synchronous motor is in a step-out state under the condition that the plurality of current peak values attenuate with time. The step-out detection method of the application can improve the reliability of detection by means of multiple detection, has strong practicability and is easy to popularize.

Description

Technical Field

[0001] This invention relates to the field of motor protection, and in particular to a detection device for refrigeration equipment and synchronous motors, and a method for detecting out-of-step behavior. Background Technology

[0002] Synchronous motors are widely used in intelligent devices due to their high efficiency and wide speed range. However, in actual operation, synchronous motors may experience step loss, resulting in a mismatch between the generated power and the preset power, which can even lead to serious consequences such as damage to the equipment.

[0003] Existing technologies include several methods for detecting synchronous motors, such as using various sensors to detect whether the synchronous motor has lost synchronization. However, these methods increase costs and are difficult to promote. Summary of the Invention

[0004] One object of the present invention is to overcome at least one defect in the prior art and to provide a detection device for refrigeration equipment and synchronous motor and a method for detecting out-of-step behavior.

[0005] A further objective of this invention is to improve the reliability of out-of-step detection for synchronous motors.

[0006] Another further objective of this invention is to detect the loss of synchronization phenomenon in a timely manner, which is prone to occur in self-synchronizing motors.

[0007] Specifically, the present invention provides a method for detecting out-of-step operation of a synchronous motor, comprising: starting the synchronous motor; identifying a running event of the synchronous motor after starting, the running event including a constant speed running event; when a constant speed running event of the synchronous motor is identified, determining whether the rotor back electromotive force of the synchronous motor is in a normal state; when the rotor back electromotive force of the synchronous motor is in a normal state, recording the current peak value of the synchronous motor within multiple consecutive preset time intervals; and determining that the synchronous motor is in an out-of-step state when the multiple current peak values ​​decay over time.

[0008] Optionally, the running event also includes an accelerated running event that transitions from a uniform running event to a subsequent uniform running event; and the steps following the identification of the synchronous motor being in a running event after startup further include: when an accelerated running event is identified, determining the warning current value of the synchronous motor; during the subsequent uniform running process, accumulating the total duration for which the real-time current of the synchronous motor is lower than the warning current value based on a preset duration period; and determining whether the synchronous motor is in a state of loss of synchronization based on the total duration.

[0009] Optionally, the step of determining whether the synchronous motor is in the out-of-step state according to the total duration further comprises: determining whether a ratio of the total duration to a preset duration period is greater than a preset ratio; if yes, determining that the synchronous motor is in the out-of-step state; and if no, determining that the synchronous motor is in the in-step state.

[0010] Optionally, the warning current value is an arithmetic mean of the plurality of current peaks.

[0011] Optionally, the preset ratio is between 3% and 20%.

[0012] Optionally, the step of determining whether the rotor back electromotive force of the synchronous motor is in the normal state further comprises: detecting a direct-axis voltage Vd and a quadrature-axis voltage Vq of the synchronous motor, and calculating a real-time rotor back electromotive force V1 of the synchronous motor, wherein V1 = sqrt(Vd^2 + Vq^2); detecting a rotor speed ω of the synchronous motor, and calculating a theoretical back electromotive force V2 corresponding to the rotor speed ω, V2 = Ke x ω, Ke being a back electromotive force constant of the synchronous motor; determining whether an error rate of the rotor back electromotive force V1 relative to the theoretical back electromotive force V2 is in a preset error rate range; if yes, determining that the synchronous motor is in the normal state; and if no, determining that the synchronous motor is in the abnormal state, and further determining that the synchronous motor is in the out-of-step state.

[0013] Optionally, the preset error rate range has a low threshold and a high threshold; the low threshold is configured to be between 5% and 15%; and the high threshold is configured to be between 40% and 60%.

[0014] Optionally, the preset time interval is configured to be between 30s and 120s.

[0015] In particular, the application further provides a detection device of a synchronous motor, which comprises a memory, a processor, and a machine-executable program stored in the memory and running on the processor, and the processor implements the out-of-step detection method of any one of the above when executing the machine-executable program.

[0016] In particular, the application further provides a refrigeration device comprising a synchronous motor and the above detection device.

[0017] The synchronous motor detection method of the application can make up for the deficiency of only using the rotor back electromotive force for determination and improve the reliability of detection, because the synchronous motor detection method adopts twice detection means in the process of uniform speed running of the synchronous motor, first determines whether the synchronous motor appears out-of-step phenomenon according to the rotor back electromotive force of the synchronous motor, and then performs secondary detection according to the current value of the synchronous motor in the case of first detection being normal, that is, compares the current peaks of the synchronous motor in a plurality of continuous preset time intervals, and determines that the synchronous motor is in the out-of-step state in the case of a plurality of current peaks decaying.

[0018] Further, the synchronous motor detection method of the present application can timely detect whether the synchronous motor has lost step in the process of increasing load (the stage where the step loss phenomenon is prone to occur) based on the total duration of the real-time current of the synchronous motor being lower than the warning current value accumulated in the preset duration period during the process of the synchronous motor running at a constant speed after the event of the synchronous motor running at a constant speed before and then accelerating, and determining whether the synchronous motor has lost step according to the relationship between the accumulated total duration and the preset duration period, thereby further improving the reliability of detection.

[0019] The above and other objects, advantages and features of the present application will become more apparent from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] Some specific embodiments of the present application will be described in detail below with reference to the accompanying drawings, in an exemplary and non-limiting manner. The same reference numerals in the drawings denote the same or similar components or parts. Those skilled in the art should understand that the drawings are not necessarily drawn to scale. In the drawings:

[0021] Figure 1 is a schematic diagram of a refrigeration device according to an embodiment of the present application;

[0022] Figure 2 is a flowchart of a step loss detection method for a synchronous motor according to an embodiment of the present application;

[0023] Figure 3 is a graph of the relationship between time and current in a running scenario of a synchronous motor according to an embodiment of the present application;

[0024] Figure 4 is a flowchart of a step loss detection method for a synchronous motor according to another embodiment of the present application. DETAILED DESCRIPTION

[0025] Reference is made to Figure 1 , Figure 1 is a schematic diagram of a refrigeration device according to an embodiment of the present application. The present application provides a refrigeration device 1, which can be understood as a device that can generate cold energy in a broad sense, such as a device known to those skilled in the art, e.g., a refrigerator, a freezer, an air conditioner, etc.

[0026] The refrigeration device 1 can include a synchronous motor 10, which can provide a power source for an electric unit requiring a power source in the refrigeration device 1. For example, in the refrigeration device 1, the synchronous motor 10 can provide power for a compressor to enable it to compress refrigerant; for another example, the synchronous motor 10 can also provide a power source for a heat exchange fan in an air conditioner, a forced air refrigerator, etc. Those skilled in the art can configure it according to actual needs.

[0027] The synchronous motor 10 generally comprises a stator and a rotor, and the rotor is supplied with a direct current excitation current, and a sinusoidal distribution magnetic field is generated on the rotor. When the synchronous motor 10 is normally operated, the stator magnetic field attracts the rotor magnetic field to operate at a synchronous speed, and the rotor magnetic field lags behind the stator magnetic field. When the permanent magnet synchronous motor 10 is operated to drive a load, there is a torque balance between the electromagnetic torque and the load torque. When the torque balance on the motor shaft is destroyed, the rotor speed and the stator speed are no longer synchronized, and the synchronous motor 10 may appear to be out of step. Once the synchronous motor 10 appears to be out of step, it may cause the equipment driven by the synchronous motor 10 to fail to achieve the expected effect, and even may cause a dangerous accident to occur.

[0028] In some embodiments, the refrigeration equipment 1 further comprises a detection device 20 of the synchronous motor 10, which is electrically connected with the synchronous motor 10 to detect whether the synchronous motor 10 is out of step during operation, and timely feedback once the synchronous motor 10 is detected to be out of step to avoid accidents.

[0029] Referring to Figure 1 , further, the detection device 20 comprises a memory 22, a processor 24, and a machine executable program 220 stored in the memory 22 and running on the processor 24, and the processor 24 implements a synchronous motor 10 out-of-step detection method when executing the machine executable program 220.

[0030] Referring to Figure 2 , Figure 2 is a flowchart of the synchronous motor 10 out-of-step detection method according to an embodiment of the present application. Specifically, the out-of-step detection method can comprise the following execution steps:

[0031] Step S310, starting the synchronous motor 10;

[0032] Step S320, identifying a running event of the synchronous motor 10 after starting, and the running event comprises a uniform speed running event, and the running event comprises the uniform speed running event;

[0033] Step S330, when the uniform speed running event of the synchronous motor 10 is identified, judging whether the rotor back electromotive force of the synchronous motor 10 is in a normal state;

[0034] Step S340, in the case that the rotor back electromotive force of the synchronous motor 10 is in the normal state, recording current peak values of the synchronous motor 10 in a plurality of continuous preset time intervals, respectively;

[0035] Step S350, in the case that the plurality of current peak values decay over time, determining that the synchronous motor 10 is in an out-of-step state.

[0036] As can be seen from the above, the synchronous motor 10 can be used to drive the electric unit in the refrigeration device 1, and such electric unit can be started and stopped by the active operation of the user and can also be started and stopped by the operation logic of the refrigeration device 1. In step S310, the process of driving the synchronous motor 10 can be the active operation of the user and can also be the automatic control of the system. In the starting process of the synchronous motor 10, the synchronous motor 10 can be preset to drive at a certain output power.

[0037] Referring to Figure 3 , Figure 3 is a time-current relationship diagram of the synchronous motor 10 in one operation scenario according to one embodiment of the present application. The operation events of the synchronous motor 10 after starting generally can include multiple events, for example, a starting event, a uniform speed operation event, an acceleration operation event, and the like.

[0038] For example (it should be noted that the following examples are only for the purpose of describing the operation stages of the synchronous motor 10 and represent a special limitation on the synchronous motor 10), when the synchronous motor 10 receives a starting instruction at a certain predetermined output power, it is considered that a starting event occurs (O-T1 period in FIG. 8), and when the starting event occurs, the current value of the synchronous motor 10 first rises and then falls. Subsequently, the real-time current value of the synchronous motor 10 fluctuates above and below the rated current corresponding to the predetermined output power, and it is considered that a uniform speed operation event occurs (T1-T2 period in FIG. 8). When the user or the system increases the output power of the synchronous motor 10, the synchronous motor 10 enters an acceleration operation from the previous uniform speed operation, and the real-time current value of the synchronous motor 10 gradually increases with the increase of the output power (T2-T3 period in FIG. 8), and when the output power is increased to the adjusted output power, the real-time current value of the synchronous motor 10 fluctuates above and below the rated current corresponding to the adjusted output power, and the synchronous motor 10 enters a subsequent uniform speed stage (T3-T4 period in FIG. 8), and it is considered that an acceleration operation event occurs. Figure 3 Figure 3 Figure 3 Figure 3

[0039] When the synchronous motor 10 starts, the magnetic flux in the rotor coil of the synchronous motor 10 will change, so that the rotor of the synchronous motor 10 generates a back electromotive force. The faster the rotor of the synchronous motor 10 rotates, the faster the magnetic flux changes, and the higher the back electromotive force of the synchronous motor 10. Therefore, the back electromotive force of the rotor of the synchronous motor 10 is proportional to the speed of the rotor. That is, when the synchronous motor 10 is normally running, the speed continuously rises with the increase of time, and the back electromotive force continuously rises, and when the target speed is reached, the speed does not change, and the back electromotive force does not change. Then, once the synchronous motor 10 loses synchronization, the rotor begins to drop, and the back electromotive force decreases.

[0040] ​​​​Therefore, in step S330, the aforementioned properties are first used to detect whether the synchronous motor 10 has lost synchronism. When an abnormal rotor back electromotive force of the synchronous motor 10 is detected, it is determined that the synchronous motor 10 has lost synchronism. At this time, the loss-of-synchronism signal can be sent to the power supply unit of the synchronous motor 10 to cut off the power supply and stop the synchronous motor 10, thus avoiding accidents caused by the loss of synchronism of the synchronous motor 10.

[0041] When the rotor back EMF of synchronous motor 10 is detected to be normal, it cannot be completely concluded that synchronous motor 10 is in a non-out-of-step state. Because the specific judgment process in step S330 requires comparing the rotor back EMF V1 with the theoretical back EMF V2 (the specific judgment steps of step S330 are described below), and the theoretical back EMF V2 introduces the back EMF constant of synchronous motor 10, since the back EMF constant is an empirical value obtained before the synchronous motor 10 leaves the factory, it may be unreliable to determine whether the synchronous motor 10 is out of step solely based on the rotor back EMF of synchronous motor 10.

[0042] Therefore, after determining in step S330 that the rotor back electromotive force of the synchronous motor 10 is in a normal state, steps S340 and S350 are also performed to perform a secondary detection on whether the synchronous motor 10 has lost synchronism, in order to ensure the reliability of the detection.

[0043] Specifically, in step S340, the peak current of the synchronous motor 10 within multiple consecutive preset time intervals is recorded. The preset time interval can be any value between 30s and 120s, such as 30s, 50s, 100s, 120s, etc.

[0044] by Figure 3 For example, the T1-T2 time period can be considered as triggering the uniform speed operation event of the synchronous motor 10. The T1-T2 time period is divided into three time periods within a preset time interval, namely the T1-t1 time period, the t1-t2 time period, and the t2-T2 time period. The peak current I1, I2, and I3 of the synchronous motor 10 are extracted and recorded in these three time periods respectively.

[0045] In step S350, the three current peaks I1, I2, and I3 can be compared to determine whether they decay over time. If so, the synchronous motor 10 is determined to be in a state of being out of step; otherwise, the synchronous motor 10 is determined to be in a state of being in a state of being out of step.

[0046] Since the synchronous motor 10 will generate more heat, increase its resistance, and decrease its current once it loses its steps, the synchronous motor 10 can be said to have lost its steps when the current value decreases over time in three time cycles. This can further improve the reliability of the detection.

[0047] In the embodiment, the more the preset time intervals are, the more the recorded current peak values of the synchronous motor 10 are, so as to ensure the diversity of sampling and the reliability of detection. In some specific embodiments, the number of the preset time intervals can also be configured to be not less than 3, that is, the recorded current peak values of the synchronous motor 10 are not less than 3, further ensuring the diversity of sampling.

[0048] In summary, the synchronous motor 10 detection method in the embodiment adopts twice detection means in the uniform speed stage. First, whether the synchronous motor 10 appears out-of-step phenomenon is determined according to the rotor back electromotive force of the synchronous motor 10. In the case that the first detection is normal, secondary detection is performed according to the current value of the synchronous motor 10, that is, the current peak values of the synchronous motor 10 in a plurality of continuous preset time intervals are compared, and in the case that a plurality of current peak values decay, it is determined that the synchronous motor 10 is in an out-of-step state. This detection method can make up for the deficiency of only using the rotor back electromotive force for determination, and improve the reliability of detection.

[0049] In some embodiments, the step of identifying that the synchronous motor 10 is in the running state after the start-up can further include:

[0050] When it is identified that the synchronous motor 10 has an acceleration running event, a warning current value of the synchronous motor 10 is determined. The warning current value can represent the lowest value of the synchronous motor 10 in the last uniform speed running.

[0051] In the process of being in the last uniform speed running, a total duration of the real-time current of the synchronous motor 10 being lower than the warning current value is accumulated based on a preset time period. In this step, the preset time period can be configured according to actual conditions, for example, any value between 30s and 120s.

[0052] According to the total duration, whether the synchronous motor 10 is in an out-of-step state is determined.

[0053] When it is detected that the synchronous motor 10 accelerates from the previous uniform speed running to the last uniform speed running, the rotating speed of the synchronous motor 10 increases, and the current value rises. When the adjustment is completed (that is, after the acceleration stage ends), the current value fluctuates around the rated current value corresponding to the output power after adjustment.

[0054] In the above step, the process of accumulating the total duration of the real-time current of the synchronous motor 10 being lower than the warning current value can be implemented by using a timer. For example, after the acceleration running ends, when it is detected that the real-time current value of the synchronous motor 10 is lower than the warning current value, the accumulation timer is started. When the real-time current value of the synchronous motor 10 is higher than the warning current value, the timer is paused. Finally, the accumulation timer task in the preset time period is completed, and the total duration is obtained.

[0055] Continue with the above exampleFigure 3 For example, Figure 3 The T3-T4 time period represents a preset time period in the last constant-speed running process of the synchronous motor 10 after the acceleration running, Ia represents the warning current value, t3 and t4 represent the time lengths in which the real-time current of the synchronous motor 10 is lower than the warning current value in the preset time period, and t3+t4 is the total duration.

[0056] When determining whether the synchronous motor 10 is in the step-out state according to the total duration, it can be determined whether the ratio of the total duration accumulated above to the preset time period is greater than a preset ratio. If it is greater than the preset ratio, it means that the current value of the synchronous motor 10 is small, and the step-out phenomenon may have occurred. If it is less than the preset ratio, it can be considered that the current value of the synchronous motor 10 is normal, and the step-out phenomenon has not occurred.

[0057] For example, Figure 3 When determining whether the synchronous motor 10 is in the step-out state according to the total duration, it can be determined whether the ratio of (t3+t4) / (T4-T3) is greater than a preset ratio.

[0058] In some specific embodiments, the preset ratio can also be configured to be any value between 3% and 20%, such as 3%, 10%, 20%, etc. Those skilled in the art can configure it according to the actual situation.

[0059] Further, the warning current value of the synchronous motor 10 can also be configured as the arithmetic mean of the current peak values recorded in a plurality of continuous preset time intervals in the last constant-speed running. Since the current value of the synchronous motor 10 after acceleration is larger than that before acceleration, using the arithmetic mean of a plurality of current peak values as the warning current value can not only ensure the reliability of the judgment basis, but also make full use of the previously collected data, further optimize the program, and save resources.

[0060] The following will introduce in detail the judgment process of step S330 in the above embodiment, i.e., whether the rotor back electromotive force of the synchronous motor 10 is in a normal state can further include the following steps:

[0061] Detect the direct-axis voltage Vd and the quadrature-axis voltage Vq of the synchronous motor 10, and calculate the real-time rotor back electromotive force V1 of the synchronous motor 10, wherein

[0062] Detect the rotor speed ω of the synchronous motor 10, and calculate the theoretical back electromotive force V2 corresponding to the rotor speed ω, V2=Ke×ω, Ke being the back electromotive force constant of the synchronous motor 10.

[0063] Determine whether the error rate N of the rotor back electromotive force V1 relative to the theoretical back electromotive force V2 is in a preset error rate interval.

[0064] If so, then the synchronous motor 10 is confirmed to be in normal condition.

[0065] If not, then the synchronous motor 10 is determined to be in an abnormal state, and thus the synchronous motor 10 is determined to be in a state of loss of synchronization.

[0066] In the above judgment process, the error rate N = |(V2-V1) / V2| × 100%. When the error rate N is within the error rate range, it can be considered that the real-time rotor back EMF V1 and the theoretical back EMF V2 are not significantly different and are within a reasonable range. At this time, a second step loss detection is required. When the error rate N exceeds the error rate range, it is considered that the real-time rotor back EMF V1 and the theoretical back EMF V2 are significantly different and are judged to be in a step loss state.

[0067] In some specific embodiments, the lower threshold of the preset error rate range can also be configured to be between 5% and 15%, such as 5%, 10%, 15%, etc. The higher threshold of the preset error rate range can also be configured to be between 40% and 60%, such as 40%, 50%, 60%, etc. Those skilled in the art should understand that selecting a reasonable point value within the above-mentioned lower and higher threshold ranges can determine the preset error rate range. For example, the preset error rate range can be 5%-40%, 12%-50%, 15%-60%, 5%-55%, 15%-50%, etc.

[0068] See Figure 4 , Figure 4 This is a flowchart of a method for detecting step loss in a synchronous motor 10 according to another embodiment of the present invention. In some more detailed embodiments, the method for detecting step loss in the synchronous motor 10 may also be performed through the following steps:

[0069] Step S410: Start the synchronous motor 10.

[0070] Step S420: Determine the running events after the synchronous motor 10 starts.

[0071] In step S420, when the synchronous motor 10 experiences a uniform speed operation event, the following steps are performed.

[0072] Step S432: Detect the direct-axis voltage Vd and quadrature-axis voltage Vq of the synchronous motor 10, and calculate the real-time rotor back electromotive force V1 of the synchronous motor 10.

[0073] Step S433: Detect the rotor speed ω of the synchronous motor 10 and calculate the theoretical back electromotive force V2 corresponding to the rotor speed ω.

[0074] Step S434: Determine whether the error rate of the rotor back EMF V1 relative to the theoretical back EMF V2 is within the preset error rate range.

[0075] If not, step S437 is performed, it is determined that the synchronous motor 10 is in an abnormal state, and it is further determined that the synchronous motor 10 is in a step-out state, and the synchronous motor 10 is shut down.

[0076] If yes, step S435 is performed, and the current peak values in a plurality of continuous preset time intervals are recorded.

[0077] Step S436 is performed to determine whether the plurality of current peak values decay over time.

[0078] If yes, step S452 is performed, it is determined that the synchronous motor 10 is in a step-out state, and the synchronous motor 10 is shut down.

[0079] If not, step S454 is performed, it is determined that the synchronous motor 10 is in a non-step-out state.

[0080] When the synchronous motor 10 has an acceleration operation event in step S420, the following steps are performed.

[0081] Step S442 is performed to determine the warning current value of the synchronous motor 10.

[0082] Step S443 is performed to detect the total duration of the real-time current of the synchronous motor 10 being lower than the warning current value in a preset time period.

[0083] Step S444 is performed to determine whether the ratio of the total duration to the preset time period is greater than a preset ratio.

[0084] If yes, step S452 is performed, it is determined that the synchronous motor 10 is in a step-out state, and the synchronous motor 10 is shut down.

[0085] If not, step S454 is performed, it is determined that the synchronous motor 10 is in a non-step-out state.

[0086] At this point, those skilled in the art should recognize that, although the present application has been fully illustrated and described herein with reference to a plurality of exemplary embodiments, many other variants or modifications in accordance with the principles of the present application can be directly determined or deduced from the disclosure of the present application without departing from the spirit and scope of the present application. Therefore, the scope of the present application should be understood and recognized as covering all such other variants or modifications.

Claims

1. A method for detecting step loss in a synchronous motor, comprising: Start the synchronous motor; Identify the running events of the synchronous motor after startup, including constant speed running events; When the synchronous motor is detected to be running at a constant speed, it is determined whether the rotor back electromotive force of the synchronous motor is in a normal state. When the rotor back electromotive force of the synchronous motor is in the normal state, the peak current of the synchronous motor is recorded in multiple consecutive preset time intervals. If multiple current peaks decay over time, the synchronous motor is determined to be in a state of being out of sync. The running event also includes an accelerated running event, which is a uniform running event that is accelerated into a uniform running event; and The steps following the identification of the synchronous motor being in operation after startup also include: When the synchronous motor is detected to have accelerated operation, the warning current value of the synchronous motor is determined. During the last uniform speed operation, the total duration during which the real-time current of the synchronous motor is lower than the warning current value is accumulated based on a preset time period. Whether the synchronous motor is out of sync is determined based on the total duration.

2. The method for detecting out-of-step movement according to claim 1, wherein the step of determining whether the synchronous motor is in a state of out-of-step movement based on the total duration further includes: Determine whether the ratio of the total duration to the preset duration period is greater than a preset ratio; If so, then the synchronous motor is determined to be in a state of being out of sync; If not, then the synchronous motor is determined to be in a non-out-of-step state.

3. The out-of-step detection method according to claim 1, wherein... The warning current value is the arithmetic mean of the multiple current peak values.

4. The out-of-step detection method according to claim 2, wherein... The preset ratio is between 3% and 20%.

5. The out-of-step detection method according to claim 1, wherein the step of determining whether the rotor back electromotive force of the synchronous motor is in a normal state further includes: The direct-axis voltage Vd and quadrature-axis voltage Vq of the synchronous motor are detected, and the real-time rotor back electromotive force V1 of the synchronous motor is calculated, where V1 = The rotor speed ω of the synchronous motor is detected, and the theoretical back electromotive force V2 corresponding to the rotor speed ω is calculated, where V2 = Ke × ω, and Ke is the back electromotive force constant of the synchronous motor. Determine whether the error rate of the rotor back electromotive force V1 relative to the theoretical back electromotive force V2 is within a preset error rate range; If so, then the synchronous motor is determined to be in the normal state; If not, then the synchronous motor is determined to be in an abnormal state, and further determined to be in a state of loss of synchronization.

6. The method for detecting out-of-step according to claim 5, wherein... The preset error rate range has a low threshold and a high threshold; The low threshold is configured to be between 5% and 15%; The high threshold is configured to be between 40% and 60%.

7. The out-of-step detection method according to claim 1, wherein... The preset time interval is configured to be between 30s and 120s.

8. A detection device for a synchronous motor, the detection device comprising a memory, a processor, and a machine-executable program stored in the memory and running on the processor, wherein the processor, when executing the machine-executable program, implements the out-of-step detection method according to any one of claims 1 to 7.

9. A refrigeration device, the refrigeration device comprising a synchronous motor and a detection device according to claim 8.

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