Open-phase detection method of three-phase motor and driver

Abstract

The invention provides an open-phase detection method of a three-phase motor and a driver. Whether any current phase winding in the three-phase motor is under-phase or not is judged according to the three-phase current effective value of the three-phase motor, whether two-phase or three-phase winding in the three-phase motor is under-phase or not is judged according to the d-axis current feedback value and the q-axis current feedback value of the three-phase motor, and therefore the under-phase fault detection method can be used for carrying out under-phase fault detection on the three-phase motor. The three-phase current effective value, the d-axis current feedback value and the q-axis current feedback value are all determined according to the three-phase current instantaneous value of the three-phase motor, and the three-phase current instantaneous value is not a new variable and needs to be detected in the running process of the three-phase motor. According to the under-phase detection method, the under-phase fault detection of the three-phase motor can be realized without adding new variables and hardware, so that the under-phase detection method can reduce the complexity of the under-phase fault detection of the three-phase motor and does not increase the hardware cost.

Description

Technical Field

[0001] The present invention relates to the technical field of three-phase motor control, and in particular to a phase loss detection method and a driver for a three-phase motor. Background Art

[0002] Compressors, fans, pumps and other dynamic equipment all need to be driven by three-phase motors. The phase failure in a three-phase motor may be a phase failure in one phase winding, or a phase failure in two phase windings or three phase windings.

[0003] As far as the inventors know, there are two main ways to detect whether a three-phase motor has the above-mentioned phase loss fault. One is achieved through hardware, and the cost is increased by adding new hardware; the other is achieved through software, but both require the addition of new variables, making the detection process more complicated.

[0004] Therefore, how to reduce the complexity of the under-phase fault detection of the three-phase motor without increasing the hardware cost is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a phase loss detection method and a driver for a three-phase motor, which reduce the complexity of phase loss fault detection of the three-phase motor without increasing hardware costs.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] On one hand, the present application provides a method for detecting a phase loss of a three-phase motor, which at least comprises:

[0008] Determining whether the three-phase motor is in a running state;

[0009] If the three-phase motor is in a running state, determining the three-phase current effective value, the d-axis current feedback value and the q-axis current feedback value of the three-phase motor at least according to the instantaneous value of the three-phase current of the three-phase motor;

[0010] When the first condition is met, it is determined that one phase of the three-phase motor is missing;

[0011] When the second condition is met, it is determined that two or three phases of the three-phase motor are missing;

[0012] The first condition at least includes being able to judge whether any current phase winding in the three-phase motor is under-phase by the effective value of the three-phase current of the three-phase motor;

[0013] The second condition at least includes being able to determine whether two or three phase windings in the three-phase motor are out of phase through the d-axis current feedback value and the q-axis current feedback value.

[0014] The present invention provides a method for detecting a phase failure of a three-phase motor. In the phase failure detection method, since the effective value of the three-phase current of the three-phase motor is used to determine whether any current phase winding in the three-phase motor is phase-deficient, and the d-axis current feedback value and the q-axis current feedback value of the three-phase motor are used to determine whether two or three-phase windings in the three-phase motor are phase-deficient, the phase failure detection method can detect a phase failure of the three-phase motor. Furthermore, since the effective value of the three-phase current, the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value are all determined according to the instantaneous value of the three-phase current of the three-phase motor, and the instantaneous value of the three-phase current is not a new variable and it needs to be detected during the operation of the three-phase motor, the phase failure detection method does not need to add new variables or new hardware to realize the phase failure detection of the three-phase motor, so the phase failure detection method can reduce the complexity of the phase failure detection of the three-phase motor without increasing the hardware cost.

[0015] Another aspect of the present application provides a driver, comprising at least a controller and a three-phase motor, wherein a signal output terminal of the controller is electrically connected to a controlled terminal of the three-phase motor,

[0016] The controller includes at least:

[0017] It can be used to determine whether the three-phase motor is in operation; if the three-phase motor is in operation, then at least according to the instantaneous value of the three-phase current of the three-phase motor, the effective value of the three-phase current, the d-axis current feedback value and the q-axis current feedback value of the three-phase motor are determined;

[0018] It can be used to determine whether one phase of a three-phase motor is missing when the first condition is met;

[0019] It can be used to determine whether two or three phases of a three-phase motor are missing when the second condition is met;

[0020] The first condition at least includes being able to judge whether any current phase winding in the three-phase motor is under-phase by the effective value of the three-phase current of the three-phase motor;

[0021] The second condition at least includes being able to judge whether two or three phase windings of the three-phase motor are lacking phases through the d-axis current feedback value and the q-axis current feedback value;

[0022] It can be used to output a stop command to the three-phase motor when it is determined that at least one winding phase of the three-phase motor is out of phase;

[0023] The three-phase motor is used to receive the stop command from the controller and stop.

[0024] The present invention provides a driver. Since the controller determines whether any current phase winding in the three-phase motor is out of phase through the effective value of the three-phase current of the three-phase motor, and determines whether two or three phase windings in the three-phase motor are out of phase through the d-axis current feedback value and the q-axis current feedback value of the three-phase motor, the controller can perform out-of-phase fault detection on the three-phase motor. Furthermore, since the effective value of the three-phase current, the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value are all determined according to the instantaneous value of the three-phase current of the three-phase motor, and the instantaneous value of the three-phase current is not a new variable and it originally needs to be detected during the operation of the three-phase motor, the controller does not need to add new variables or new hardware to realize the controller's out-of-phase fault detection of the three-phase motor, thereby reducing the complexity of the out-of-phase fault detection of the three-phase motor without increasing the hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0026] Figure 1 A schematic flow chart of a first implementation of a method for detecting phase loss in a three-phase motor provided in an embodiment of the present application;

[0027] Figure 2 A schematic flow chart of a second implementation of a method for detecting phase loss in a three-phase motor provided in an embodiment of the present application;

[0028] Figure 3 A schematic flow chart of a third implementation of the method for detecting phase loss of a three-phase motor provided in an embodiment of the present application;

[0029] Figure 4 A schematic diagram of a flow chart of a first implementation method of determining whether any current phase winding in a three-phase motor is under-phase provided in an embodiment of the present application;

[0030] Figure 5 A schematic diagram of a flow chart of a second implementation method of determining whether any current phase winding in a three-phase motor is under-phase provided in an embodiment of the present application;

[0031] Figure 6 A schematic diagram of a flow chart of a third implementation method of determining whether any current phase winding in a three-phase motor is under-phase provided in an embodiment of the present application;

[0032] Figure 7 A schematic diagram of a first implementation method of determining whether two or three phase windings of a three-phase motor are missing phases provided in an embodiment of the present application;

[0033] Figure 8A schematic diagram of a second implementation of determining whether two or three phase windings of a three-phase motor are missing phases provided in an embodiment of the present application;

[0034] Fig. 9 A flowchart of a third implementation method for determining whether two or three phase windings in a three-phase motor are missing phases is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to describe the technical solutions in the embodiments of the present application more clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other technical solutions obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In this application, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0037] In order to reduce the complexity of the phase failure detection of the three-phase motor and not increase the hardware cost, the embodiment of the present application provides an implementation method of the phase failure detection method of the three-phase motor, and the specific process is as follows: Figure 1 As shown, it specifically includes at least the following steps:

[0038] S110, at least determine whether the three-phase motor is in operation.

[0039] If the three-phase motor is in the running state, the subsequent steps are executed in sequence; if the three-phase motor is not in the running state, the subsequent steps are stopped.

[0040] The operating state refers to the state of the three-phase motor when it is operating normally. In other words, the three-phase motor is in the operating state, which indicates that the three-phase motor is operating normally.

[0041] In practical applications, the subsequent steps can be stopped by keeping silent or blocking the output port, which is not specifically limited here and can be determined according to the specific situation. In addition, the following embodiments stop the subsequent steps in the same manner and will not be described in detail.

[0042] It should be noted that how to determine whether a three-phase motor is in operation is already very mature in the prior art and will not be described in detail here.

[0043] S120. Determine the effective value of the three-phase current of the three-phase motor at least based on the instantaneous value of the three-phase current of the three-phase motor.

[0044] The instantaneous value of one phase current of a three-phase motor refers to the instantaneous value of the current of the phase of the three-phase motor. Specifically, the instantaneous value of the three-phase current of the three-phase motor specifically includes: the instantaneous value of the U-phase current iu, the instantaneous value of the V-phase current iv, and the instantaneous value of the W-phase current iw.

[0045] It should be noted that the instantaneous value of one-phase current of a three-phase motor is already very mature in the prior art and will not be described in detail here.

[0046] The effective value of one phase current of a three-phase motor refers to the effective value of the current of the phase of the three-phase motor. Specifically, the effective value of the three-phase current of the three-phase motor specifically includes: the effective value of the U-phase current iuRMS, the effective value of the V-phase current ivRMS, and the effective value of the W-phase current iwRMS.

[0047] It should be noted that the effective value of one-phase current of a three-phase motor is already very mature in the prior art, and will not be described in detail here. In addition, the method of determining the effective value of the three-phase current of the three-phase motor according to the instantaneous value of the three-phase current of the three-phase motor is already very mature in the prior art, and will not be described in detail here.

[0048] S130. Determine a d-axis current feedback value and a q-axis current feedback value of the three-phase motor at least based on the instantaneous value of the three-phase current of the three-phase motor.

[0049] The above-mentioned d-axis current feedback value refers to the d-axis current obtained after the instantaneous value of the three-phase current of the three-phase motor is transformed by Clark and Park. The above-mentioned q-axis current feedback value refers to the q-axis current obtained after the instantaneous value of the three-phase current of the three-phase motor is transformed by Clark and Park.

[0050] It should be noted that, according to the instantaneous value of the three-phase current of the three-phase motor, determining the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value is already very mature in the prior art, and will not be described in detail here.

[0051] S140. Whether any current phase winding in the three-phase motor is under-phase can be determined at least by using the effective value of the three-phase current of the three-phase motor.

[0052] Among them, any current phase winding in the three-phase motor is out of phase means that in the three-phase motor, only the current phase winding is out of phase. Any current phase winding refers to any phase in the three-phase motor, for example, the U-phase winding.

[0053] In this embodiment, at least the three-phase current effective value of the three-phase motor can be used to determine whether any current phase winding in the three-phase motor is under-phase. For example, the effective value of any current phase current is compared with a threshold value, where the threshold value can be a fixed threshold value or an adaptive threshold value. The adaptive threshold value can be determined by a segmented table lookup method, and of course, other methods that meet the above conditions can be used for determination, not limited to the examples given.

[0054] S150. It is at least possible to determine whether two or three phase windings in the three-phase motor are lacking in phase by at least using the above d-axis current feedback value and the above q-axis current feedback value.

[0055] Two or three phase windings in a three-phase motor are out of phase, which means that two or three phase windings in a three-phase motor are out of phase.

[0056] In this embodiment, at least the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value can be used to determine whether two or three phases of the three-phase motor are under-phase. For example, the method can be used to compare the effective value of any current phase current with a threshold value, where the threshold value can be a fixed threshold value or an adaptive threshold value. The adaptive threshold value can be a segmented table lookup method, and of course, it can also be judged in a way that meets the above conditions, and is not limited to the examples given.

[0057] Although the sequence number is indicated before each step, such as S110~S150, it is actually limited by the limitation of text expression. In actual application, it is not necessarily executed in the order from small to large sequence numbers. Specifically, as long as the following requirements are met, the execution order between the steps can be arranged at will: step S110 must be executed before steps S120~step S150, step S120 must be executed before step S140, and step S130 must be executed before step S150.

[0058] For example, Figure 1 As shown, steps S110 to S150 are executed in ascending order of serial numbers.

[0059] For example, Figure 2As shown, step S110 is performed first, step S120 is performed after step S110, step S140 is performed after step S120, step S130 is performed after step S140, and step S150 is performed after step S130.

[0060] For example, Figure 3 As shown, step S110 is executed first, and after step S110, step S120 and step S130 are executed simultaneously. If step S120 is satisfied, step S140 is executed, and if step S130 is satisfied, step S150 is executed.

[0061] It should be noted that, in addition to the above three examples, other implementation methods that meet the above requirements can also be adopted, not limited to the above three examples, and no specific limitation is made here, which can be determined according to the specific situation.

[0062] In this embodiment, since the effective value of the three-phase current of the three-phase motor is used to determine whether any current phase winding in the three-phase motor is out of phase, and the d-axis current feedback value and q-axis current feedback value of the three-phase motor are used to determine whether two or three phase windings in the three-phase motor are out of phase, the out-of-phase detection method can detect the out-of-phase fault of the three-phase motor. In addition, since the effective value of the three-phase current, the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value are all determined according to the instantaneous value of the three-phase current of the three-phase motor, and the instantaneous value of the three-phase current is not a new variable and it needs to be detected during the operation of the three-phase motor, the out-of-phase detection method does not need to add new variables or new hardware to realize the out-of-phase fault detection of the three-phase motor. Therefore, the out-of-phase detection method can reduce the complexity of the out-of-phase fault detection of the three-phase motor without increasing the hardware cost.

[0063] In addition, in this embodiment, the effective value of the three-phase current of the three-phase motor is used to determine whether any current phase winding in the three-phase motor is out of phase, so this implementation method can determine which phase winding in the three-phase motor is out of phase, which is conducive to quickly troubleshooting.

[0064] Another embodiment of the present application provides a specific implementation method that can at least determine whether any current phase winding in the three-phase motor is under-phase by using the effective value of the three-phase current of the three-phase motor. The specific process is as follows: Figure 4 As shown, the specific steps include:

[0065] S210. It is possible to determine whether the effective value of any current phase current of the three-phase motor is less than the first threshold, and whether the effective values ​​of the remaining two phase currents of the three-phase motor are both greater than the second threshold.

[0066] If the effective value of any current phase current of the three-phase motor is less than the first threshold, and the effective values ​​of the remaining two phase currents of the three-phase motor are greater than the second threshold, execute step S220; if the effective value of any current phase current of the three-phase motor is greater than or equal to the first threshold, and / or the effective values ​​of the remaining two phase currents of the three-phase motor are not greater than the second threshold, stop executing subsequent steps.

[0067] In this embodiment, the first threshold and the second threshold can be fixed thresholds or adaptive thresholds. The adaptive threshold can be a segmented table lookup method. By judging the two thresholds, instantaneous interference such as electromagnetic pulse signals can be avoided, thereby improving detection accuracy.

[0068] Any current effective value of the three-phase motor's current is less than the first threshold, indicating that the effective value of the current of this phase of the three-phase motor is very small. In other words, it indicates that the amplitude of the current of this phase of the three-phase motor is very small. On the contrary, any current effective value of the three-phase motor's current is greater than or equal to the first threshold, indicating that the effective value of the current of this phase of the three-phase motor is not very small. In other words, it indicates that the amplitude of the current of this phase of the three-phase motor is not very small. In practical applications, the first threshold is set according to actual conditions and is not specifically limited here.

[0069] The effective values ​​of the remaining two-phase currents of the three-phase motor are all greater than the second threshold value, indicating that the effective values ​​of the two-phase currents of the three-phase motor are both large. In other words, it indicates that the amplitudes of the two-phase currents of the three-phase motor are both large. On the contrary, the effective values ​​of the remaining two-phase currents of the three-phase motor are less than or equal to the second threshold value, indicating that the effective values ​​of the two-phase currents of the three-phase motor are not both large. In other words, it indicates that the amplitudes of the two-phase currents of the three-phase motor are not both large. In practical applications, the second threshold value is set according to actual conditions and is not specifically limited here.

[0070] S220, determining whether any current phase winding in the three-phase motor is under-phase.

[0071] It should be noted that any current phase winding of the three-phase motor is out of phase, which has been described in detail in the above embodiments and will not be repeated here.

[0072] For example, assuming that any current phase winding is the U-phase winding, and the other two phase windings are the V-phase winding and the W-phase winding, if the U-phase current effective value iuRMS is less than the first threshold, and the V-phase current effective value ivRMS and the W-phase current effective value iwRMS of the three-phase motor are both greater than the second threshold, it is determined that the U-phase winding is out of phase.

[0073] In this embodiment, since the effective value of the current phase current of the three-phase motor is less than the first threshold value, it is equivalent to: the effective value of the current of the phase of the three-phase motor is very small, that is, the amplitude of the current of the phase of the three-phase motor is very small, so if the three-phase motor meets this condition, it means that the current of the phase of the three-phase motor is very small. Since the effective values ​​of the remaining two phase currents of the three-phase motor are all greater than the second threshold value, it is equivalent to: the effective values ​​of the two phase currents of the three-phase motor are both very large, that is, the amplitudes of the two phase currents of the three-phase motor are both very large, so if the three-phase motor meets this condition, it means that the two phase currents of the three-phase motor are very large. In summary, if the three-phase motor is in a running state and satisfies the above two conditions at the same time, it means that any current phase current of the three-phase motor is very small and the other two phase currents are very large, which meets the characteristics of the current of each phase of the three-phase motor when any current phase winding in the three-phase motor is out of phase. Therefore, in this case, it is determined that any current phase winding in the three-phase motor is out of phase, so this implementation method can detect whether any current phase winding in the three-phase motor is out of phase.

[0074] Another embodiment of the present application provides another specific implementation method that can determine whether any one phase winding in a three-phase motor is missing phase by at least the effective value of the three-phase current of the three-phase motor. The difference between this implementation method and the above implementation method is that:

[0075] In this embodiment, the first threshold is equal to one fourth of the sum of the effective values ​​of the three-phase currents of the three-phase motor, and / or the second threshold is equal to one third of the sum of the effective values ​​of the three-phase currents of the three-phase motor.

[0076] When the first threshold is equal to one-fourth of the sum of the effective values ​​of the three-phase current of the three-phase motor and the second threshold is equal to one-third of the sum of the effective values ​​of the three-phase current of the three-phase motor, assuming that any current phase winding is the U-phase winding and the other two phase windings are the V-phase winding and the W-phase winding, if iuRMS﹤(iuRMS+ivRMS+iwRMS) / 4 and ivRMS﹥(iuRMS+ivRMS+iwRMS) / 3 and iwRMS﹥(iuRMS+ivRMS+iwRMS) / 3, it is determined that the U-phase winding is out of phase.

[0077] When the three-phase motor is operating normally, the effective values ​​of the three-phase currents of the three-phase motor are equal, that is, the effective value of each phase current of the three-phase motor is equal to one third of the sum of the effective values ​​of the three-phase currents of the three-phase motor. Therefore, if the effective value of any current phase current of the three-phase motor is less than one fourth of the sum of the effective values ​​of the three-phase currents of the three-phase motor, it can be indicated that the effective value of the phase current of the three-phase motor is very small. Therefore, the first threshold is equal to one fourth of the sum of the effective values ​​of the three-phase currents of the three-phase motor, which can ensure that: if the effective value of any current phase current of the three-phase motor is less than the first threshold, it can be indicated that the effective value of the phase current of the three-phase motor is very small.

[0078] When the three-phase motor is operating normally, the effective values ​​of the three-phase currents of the three-phase motor are equal, that is, the effective value of each phase current of the three-phase motor is equal to one third of the sum of the effective values ​​of the three-phase currents of the three-phase motor. Therefore, if the effective values ​​of the remaining two phase currents of the three-phase motor are greater than one third of the sum of the effective values ​​of the three-phase currents of the three-phase motor, it can be indicated that the effective values ​​of these two phase currents of the three-phase motor are very large. Therefore, the second threshold is greater than or equal to one third of the sum of the effective values ​​of the three-phase currents of the three-phase motor, which can ensure that: the effective values ​​of the remaining two phase currents of the three-phase motor are greater than the second threshold, which can indicate that the effective values ​​of these two phase currents of the three-phase motor are very large.

[0079] In this embodiment, since the first threshold and the second threshold are both related to the sum of the effective values ​​of the three-phase current of the three-phase motor, adaptive adjustment of the threshold is achieved, thereby reducing the possibility of false detection of the phase loss detection method.

[0080] Another embodiment of the present application provides another specific implementation method that can at least determine whether any current phase winding in the three-phase motor is under-phase by using the effective value of the three-phase current of the three-phase motor. The specific process can be found in Figure 5 This implementation includes step S210 to determine whether the effective value of any current phase current of the three-phase motor is less than a first threshold value and the effective values ​​of the remaining two phase currents of the three-phase motor are greater than a second threshold value. If the conditions are met, the following steps are also included:

[0081] S310. It is possible to determine the instantaneous current sine wave period of the three-phase motor according to the rotation speed and pole pair number of the three-phase motor.

[0082] Specifically, the instantaneous current sine wave period of the three-phase motor is determined by the following formula:

[0083] T = 60 / (n×P)

[0084] Among them, T is the instantaneous current sine wave period of the three-phase motor, n is the speed of the three-phase motor, and p is the number of pole pairs of the three-phase motor.

[0085] S320, determine whether the effective value of any current phase current of the three-phase motor is less than the first threshold value for N1 current sinusoidal wave cycles, and whether the effective values ​​of the remaining two phase currents of the three-phase motor are greater than the second threshold value.

[0086] If the effective value of any current phase current of the three-phase motor is less than the first threshold value for N1 cycles of the instantaneous current sine wave, and the effective values ​​of the remaining two phase currents of the three-phase motor are greater than the second threshold value, execute step S220; if the effective value of any current phase current of the three-phase motor is less than the first threshold value for N1 cycles of the instantaneous current sine wave, and the effective values ​​of the remaining two phase currents of the three-phase motor are greater than the second threshold value, stop executing subsequent steps.

[0087] Wherein, N1 is a positive integer, and the value of N1 may be determined according to the circumstances and is not specifically limited here.

[0088] In this embodiment, by adding steps S310 and S320, it is necessary to meet the following conditions within a continuous period of time: the effective value of any current phase current of the three-phase motor is less than the first threshold value and the effective values ​​of the other two phase currents of the three-phase motor are greater than or equal to the second threshold value, in order to determine whether any current phase winding in the three-phase motor is out of phase. Therefore, the possibility of false detection when detecting whether any current phase winding in the three-phase motor is out of phase can be further reduced.

[0089] In addition, step S310 may be performed between step S210 and step S320 or before step S210. Figure 6 As shown, in practical applications, including but not limited to this, as long as the implementation methods of step S310 before step S320 are within the protection scope of this application, no specific limitation is made here and it may depend on the specific situation.

[0090] Another embodiment of the present application provides an implementation method that can at least determine whether two or three phase windings in the three-phase motor are lacking phases by using the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value. The specific process is as follows: Figure 7 As shown, the specific steps include:

[0091] S410: It is possible to determine whether the square sum of the d-axis current feedback value and the q-axis current feedback value is less than a third threshold.

[0092] If the square sum of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold, step S420 is executed; if the square sum of the d-axis current feedback value and the q-axis current feedback value is greater than or equal to the third threshold, execution is stopped.

[0093] In this embodiment, the third threshold value may be a fixed threshold value or an adaptive threshold value. The adaptive threshold value may adopt a segmented table lookup method or the like.

[0094] The sum of the squares of the d-axis current feedback value and the q-axis current feedback value specifically refers to: the sum of the squares of the d-axis current feedback value and the squares of the q-axis current feedback value.

[0095] The sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value, indicating that the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is very small. In other words, it indicates that the instantaneous value of the three-phase current of the three-phase motor is very small. On the contrary, the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is greater than or equal to the third threshold value, indicating that the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is not very small. In other words, it indicates that the instantaneous value of the three-phase current of the three-phase motor is not very small. In practical applications, the third threshold value is set according to actual conditions and is not specifically limited here.

[0096] S420, determining whether two or three phase windings of the three-phase motor are missing a phase.

[0097] It should be noted that the lack of phases in two or three phase windings of the three-phase motor has been described in detail in the above embodiments and will not be repeated here.

[0098] In this embodiment, since the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value, it is equivalent to: the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is very small, that is, the instantaneous value of the three-phase current of the three-phase motor is very small, so if the three-phase motor meets this condition, it means that the three-phase currents of the three-phase motor are all very small, which is consistent with the characteristics of the currents of each phase of the three-phase motor when two or three-phase windings in the three-phase motor are out of phase. Therefore, in this case, it is determined that two or three-phase windings in the three-phase motor are out of phase, so this implementation method can detect whether two or three-phase windings in the three-phase motor are out of phase.

[0099] Another embodiment of the present application provides another specific implementation method that can determine whether two or three phase windings in a three-phase motor are lacking phases by at least using the above d-axis current feedback value and the above q-axis current feedback value. The difference between this implementation method and the above implementation method is that:

[0100] In this embodiment, the third threshold is equal to half of the square of the current vector command value of the three-phase motor.

[0101] When the third threshold is equal to half of the square of the current vector command value of the three-phase motor, if Idf2+Iqf2﹤Is2 / 2, it is determined that two or three phases of the three-phase motor winding are out of phase. Wherein, Idf is the d-axis current feedback value, Iqf is the q-axis current feedback value, and Is is the current vector command value of the three-phase motor.

[0102] The current vector command value is a specified value of the modulus of the current command vector in the vector control of the three-phase motor. In addition, the current vector command value is obtained from the vector control of the three-phase motor. Specifically, the current command vector is equal to the vector sum of the d-axis current of the three-phase motor and the q-axis current of the three-phase motor.

[0103] Normally, when the vector control of the three-phase motor reaches stability, the square of the specified value of the modulus of the current command vector is equal to the sum of the squares of the d-axis current feedback value and the q-axis current feedback value, that is, the square of the current vector command value of the three-phase motor is equal to the sum of the squares of the d-axis current feedback value and the q-axis current feedback value. Therefore, if the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than half of the square of the current command vector command value, it indicates that the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is very small.

[0104] In this embodiment, since the third threshold is related to the current vector command value of the three-phase motor, there is no artificial setting of the threshold, and adaptive adjustment of the threshold is achieved, thereby reducing the possibility of false detection of the phase loss detection method.

[0105] Another embodiment of the present application provides another specific implementation method that can determine whether two or three phase windings in the three-phase motor are lacking phases by at least the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value. The specific process can be found in Figure 8 In the above embodiment, when the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value, this embodiment further includes the following steps:

[0106] S510. It is possible to determine the instantaneous current sine wave period of the three-phase motor according to the rotation speed and pole pair number of the three-phase motor.

[0107] It should be noted that the method for determining the instantaneous current sine wave period of the three-phase motor according to the rotation speed and pole pair number of the three-phase motor is the same as step S310 and will not be repeated here.

[0108] S520: Determine whether the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than a third threshold value for N2 consecutive current sine wave cycles.

[0109] If the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value for N2 cycles of the instantaneous current sine wave, step S720 is executed; if the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value for not N2 cycles of the instantaneous current sine wave, subsequent steps are stopped.

[0110] Wherein, N2 is a positive integer, and the value of N2 may be determined according to the circumstances and is not specifically limited here.

[0111] In this embodiment, by adding steps S510 and S520, this implementation method is implemented only when the following conditions are met within a continuous period of time: the sum of the squares of the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value is less than the third threshold value, in order to determine whether two or three-phase windings in the three-phase motor are out of phase. Therefore, the possibility of false detection when detecting whether two or three-phase windings in the three-phase motor are out of phase can be further reduced.

[0112] In addition, step S510 may be performed between step S410 and step S520 or before step S410. Fig. 9 As shown, in practical applications, including but not limited to this, as long as the implementation methods of step S510 before step S520 are within the protection scope of this application, no specific limitation is made here and it may depend on the specific situation.

[0113] Another embodiment of the present application provides another implementation of a method for detecting a phase loss of a three-phase motor. The difference between this implementation and any of the above implementations is that:

[0114] In this embodiment, the instantaneous values ​​of the three-phase current of the three-phase motor are obtained from the vector control of the motor. Specifically, the instantaneous values ​​of the three-phase current of the motor are obtained from the sampling of the drive board current. As for the drive board current, it is already very mature in the prior art and will not be repeated here.

[0115] It should be noted that the vector control of a three-phase motor is a three-phase motor control strategy, which is a variable frequency drive control method for controlling a three-phase motor by controlling the amplitude and frequency of the output voltage of the motor controller of the three-phase motor. It is already very mature in the prior art and will not be described in detail here. Generally, the control loop of a three-phase motor includes a current loop and a speed loop.

[0116] Another embodiment of the present application provides a driver, which at least includes: a controller and a three-phase motor. The signal output end of the controller is electrically connected to the controlled end of the three-phase motor.

[0117] The controller includes at least:

[0118] It can at least be used to determine whether the three-phase motor is in operation; if the three-phase motor is in operation, then at least the three-phase current effective value, d-axis current feedback value and q-axis current feedback value of the three-phase motor are determined based on the instantaneous value of the three-phase current of the three-phase motor.

[0119] It can be used to determine whether any current phase winding in the three-phase motor is under-phased through the effective value of the three-phase current of the three-phase motor.

[0120] At least it can be used to determine whether two or three phase windings in the three-phase motor are out of phase through the above d-axis current feedback value and the above q-axis current feedback value.

[0121] It can be used to output a stop command to the three-phase motor when it is determined that at least one phase of the winding in the three-phase motor is out of phase.

[0122] It should be noted that the three-phase motor is in a running state, the instantaneous value of the three-phase current of the three-phase motor, the effective value of the three-phase current of the three-phase motor, the above-mentioned d-axis current feedback value, the above-mentioned q-axis current feedback value, two-phase or three-phase windings in the three-phase motor are out of phase, and any current phase winding in the three-phase motor is out of phase, all of which have been described in detail in the above embodiments and will not be repeated here.

[0123] The three-phase motor can be used to receive control instructions from the controller and execute corresponding control instructions.

[0124] In this embodiment, since the controller determines whether any current phase winding in the three-phase motor is out of phase through the effective value of the three-phase current of the three-phase motor, and determines whether two or three phase windings in the three-phase motor are out of phase through the d-axis current feedback value and the q-axis current feedback value of the three-phase motor, the controller can perform out-of-phase fault detection on the three-phase motor. In addition, since the effective value of the three-phase current, the above-mentioned d-axis current feedback value and the above-mentioned q-axis current feedback value are all determined according to the instantaneous value of the three-phase current of the three-phase motor, and the instantaneous value of the three-phase current is not a new variable and it needs to be detected during the operation of the three-phase motor, the controller does not need to add new variables or new hardware to realize the controller's out-of-phase fault detection of the three-phase motor, thereby reducing the complexity of the out-of-phase fault detection of the three-phase motor without increasing the hardware cost.

[0125] In addition, since the effective value of the three-phase current of the three-phase motor is used to determine whether any current phase winding in the three-phase motor is out of phase, the controller can determine which phase winding in the three-phase motor is out of phase, which is conducive to quickly troubleshooting.

[0126] Another embodiment of the present application provides another implementation of the driver, which is different from the above implementation in that:

[0127] In this embodiment, the controller can at least be used to determine whether any current phase winding in the three-phase motor is under-phase by means of the effective value of the three-phase current of the three-phase motor, specifically including:

[0128] It can determine whether the effective value of any current phase current of the three-phase motor is less than the first threshold, and whether the effective values ​​of the other two phase currents of the three-phase motor are greater than the second threshold. If the effective value of any current phase current of the three-phase motor is less than the first threshold, and the effective values ​​of the other two phase currents of the three-phase motor are greater than the second threshold, it is determined that any current phase winding in the three-phase motor is out of phase.

[0129] It should be noted that any current phase current effective value of the three-phase motor, the remaining two phase current effective values ​​of the three-phase motor, the implementation method of the first threshold value, and the implementation method of the second threshold value are all described in detail in the above embodiments and will not be repeated here.

[0130] In this embodiment, since the effective value of any current phase current of the three-phase motor is less than the first threshold value, it is equivalent to: the effective value of the current of this phase of the three-phase motor is very small, that is, the amplitude of the current of this phase of the three-phase motor is very small, so if the three-phase motor meets this condition, it means that the current of this phase of the three-phase motor is very small. Since the effective values ​​of the remaining two phase currents of the three-phase motor are all greater than the second threshold value, it is equivalent to: the effective values ​​of the two phase currents of the three-phase motor are both very large, that is, the amplitudes of the two phase currents of the three-phase motor are both very large, so if the three-phase motor meets this condition, it means that the two phase currents of the three-phase motor are very large. In summary, if the three-phase motor is in a running state and satisfies the above two conditions at the same time, it means that the current of any current phase of the three-phase motor is very small and the currents of the remaining two phases are very large, which meets the characteristics of the currents of each phase of the three-phase motor when any current phase winding in the three-phase motor is out of phase. Therefore, in this case, it is determined that any current phase winding in the three-phase motor is out of phase, so that the controller can detect whether any current phase winding in the three-phase motor is out of phase.

[0131] In another embodiment of the present application, a driver is provided, and the difference between the embodiment and the above embodiment is that:

[0132] In this embodiment, the controller can at least be used to determine whether two or three phase windings in the three-phase motor are lacking phases through the above d-axis current feedback value and the above q-axis current feedback value, specifically including:

[0133] It is possible to determine whether the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than a third threshold value. If the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value, it is determined that two or three phases of the three-phase motor winding are under-phase.

[0134] It should be noted that the implementation of the d-axis current feedback value, the q-axis current feedback value, and the third threshold value are described in detail in the above embodiments and will not be repeated here.

[0135] In this embodiment, since the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold value, it is equivalent to: the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is very small, that is, the instantaneous value of the three-phase current of the three-phase motor is very small, so if the three-phase motor meets this condition, it means that the three-phase currents of the three-phase motor are all very small, which is consistent with the characteristics of the currents of each phase of the three-phase motor when two or three-phase windings in the three-phase motor are out of phase. Therefore, in this case, it is determined that two or three-phase windings in the three-phase motor are out of phase, so that the controller can detect whether two or three-phase windings in the three-phase motor are out of phase.

[0136] When the above technical solution is applied to a driver, the controller may refer to a control chip in the driver.

[0137] The drivers here can be used in systems such as air conditioning.

[0138] The above specific examples are used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A method for detecting phase loss of a three-phase motor, characterized in that: At least: Determining whether the three-phase motor is in a running state; If the three-phase motor is in a running state, determining the three-phase current effective value, the d-axis current feedback value and the q-axis current feedback value of the three-phase motor at least according to the instantaneous value of the three-phase current of the three-phase motor; When the first condition is met, it is determined that one phase of the three-phase motor is missing; When the second condition is met, it is determined that two or three phases of the three-phase motor are missing; The first condition at least includes being able to judge whether any current phase winding in the three-phase motor is under-phase by the effective value of the three-phase current of the three-phase motor; The second condition at least includes being able to determine whether two or three phase windings in the three-phase motor are out of phase through the d-axis current feedback value and the q-axis current feedback value.

2. The method for detecting phase loss of a three-phase motor according to claim 1, characterized in that: Being able to judge whether any current phase winding in the three-phase motor is under-phase by the effective value of the three-phase current of the three-phase motor at least includes: It is possible to determine whether the effective value of any current phase current of the three-phase motor is less than a first threshold value, and whether the effective values ​​of the remaining two phase currents of the three-phase motor are both greater than a second threshold value; If the effective value of any current phase current of the three-phase motor is less than the first threshold value, and the effective values ​​of the other two phase currents of the three-phase motor are greater than the second threshold value, it is determined that any current phase winding of the three-phase motor is out of phase.

3. The method for detecting phase loss of a three-phase motor according to claim 2, characterized in that: The first threshold is equal to one quarter of the sum of the effective values ​​of the three-phase currents of the three-phase motor; and / or, The second threshold is equal to one third of the sum of the effective values ​​of the three-phase currents of the three-phase motor.

4. The method for detecting phase loss of a three-phase motor according to claim 1, characterized in that: Also includes: The instantaneous current sine wave period of the three-phase motor can be determined according to the rotation speed and the number of pole pairs of the three-phase motor; If the effective value of any current phase current of the three-phase motor is less than the first threshold value for N1 consecutive cycles of the instantaneous current sine wave, and the effective values ​​of the currents of the other two phases of the three-phase motor are greater than the second threshold value, it is determined that any current phase winding of the three-phase motor is out of phase; Wherein N1 is a positive integer.

5. The method for detecting phase loss of a three-phase motor according to any one of claims 1 to 4, characterized in that: Being able to judge whether two or three phase windings in the three-phase motor are lacking phases through the d-axis current feedback value and the q-axis current feedback value, at least includes: capable of judging whether the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than a third threshold; If the square sum of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold, it is determined that two or three phase windings of the three-phase motor are missing a phase.

6. The method for detecting phase loss of a three-phase motor according to claim 5, characterized in that: The third threshold is equal to half of the square of the current vector command value of the three-phase motor.

7. The method for detecting phase loss of a three-phase motor according to claim 1, characterized in that: Also includes: The instantaneous current sine wave period of the three-phase motor can be determined according to the rotation speed and the number of pole pairs of the three-phase motor; If the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than a third threshold value for N2 consecutive cycles of the instantaneous current sine wave, it is determined that two or three phases of the windings of the three-phase motor are out of phase; Wherein, N2 is a positive integer.

8. A driver, comprising at least a controller and a three-phase motor, wherein a signal output end of the controller is electrically connected to a controlled end of the three-phase motor, characterized in that: The controller at least comprises: It can be used to determine whether the three-phase motor is in a running state; if the three-phase motor is in a running state, then at least according to the instantaneous value of the three-phase current of the three-phase motor, determine the three-phase current effective value, d-axis current feedback value and q-axis current feedback value of the three-phase motor; It can be used to determine whether one phase of a three-phase motor is missing when the first condition is met; It can be used to determine whether two or three phases of a three-phase motor are missing when the second condition is met; The first condition at least includes being able to judge whether any current phase winding in the three-phase motor is under-phase by the effective value of the three-phase current of the three-phase motor; The second condition at least includes being able to judge whether two or three phase windings of the three-phase motor are lacking phases through the d-axis current feedback value and the q-axis current feedback value; can be used to output a stop command to the three-phase motor when it is determined that at least one winding phase of the three-phase motor is out of phase; The three-phase motor can be used to receive a stop instruction from the controller and stop.

9. The driver according to claim 8, characterized in that: The controller can be used to determine whether any current phase winding in the three-phase motor is under-phase by means of the effective value of the three-phase current of the three-phase motor, and at least includes: It is possible to determine whether the effective value of any current phase current of the three-phase motor is less than a first threshold value, and whether the effective values ​​of the remaining two phase currents of the three-phase motor are both greater than a second threshold value; If the effective value of any current phase current of the three-phase motor is less than the first threshold value, and the effective values ​​of the other two phase currents of the three-phase motor are greater than the second threshold value, it is determined that any current phase winding of the three-phase motor is out of phase.

10. The driver according to claim 8 or 9, characterized in that: The controller can be used to determine whether two or three phase windings in the three-phase motor are out of phase through the d-axis current feedback value and the q-axis current feedback value, and at least includes: capable of judging whether the sum of the squares of the d-axis current feedback value and the q-axis current feedback value is less than a third threshold; If the square sum of the d-axis current feedback value and the q-axis current feedback value is less than the third threshold, it is determined that two or three phase windings of the three-phase motor are missing a phase.

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