JP2012130121A - Motor control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of diagnosis of abnormalities in a motor driving unit 22.SOLUTION: The motor control system comprises: the motor driving unit 22 comprising an inverter 4 for converting DC power into three-phase AC power and a three-phase induction motor 1 driven by the AC power converted by the inverter 4; a current abnormality detection unit 23a which detects a current abnormality when the value of a current flowing through the inverter 4 exceeds a predetermined threshold; and an abnormality processing unit 6 which diagnoses the motor driving unit 22 as having an abnormality when the current abnormalities are periodically detected.

Description

  The present invention relates to a motor control system for diagnosing abnormalities such as disconnection and poor connection of a three-phase induction motor.

  When driving a three-phase induction motor, a motor drive device is used in which power from a DC power source is converted into AC power by an inverter and the torque of the three-phase induction motor is controlled by PWM control of the inverter.

  When one phase of the three-phase induction motor is disconnected or when one of the motor terminals U, V, W is disconnected, the ripple peak value of the input current to the inverter circuit is Become bigger. Therefore, in Patent Document 1, the input current to the inverter unit is detected using a shunt resistor, and the abnormality of the three-phase induction motor is detected according to the time when the ripple peak value of the input current exceeds a predetermined threshold value. I have a diagnosis.

Japanese Patent Laid-Open No. 6-133591

  As shown in FIG. 13, in Patent Document 1, when the time during which the ripple peak value CD1 of the input current continuously exceeds the predetermined threshold is equal to or longer than the predetermined abnormality determination time HT, it is determined as abnormal. ing. Therefore, when the time HS during which the ripple peak value CD2 of the input current exceeds the predetermined threshold value is less than the abnormality determination time HT, the abnormality cannot be detected.

  In other words, if an attempt is made to determine an abnormality in the motor drive unit based on the duration of the current abnormality, an inconsistency between the abnormality determination time HT and the actual occurrence state of the abnormality necessarily occurs. For this reason, the abnormality of a three-phase induction motor cannot be diagnosed correctly, but there existed a subject that a diagnostic precision fell.

  In view of the above problems, an object of the present invention is to improve abnormality diagnosis accuracy of a motor drive unit.

  One aspect of the present invention that achieves the above object is a motor control system including an inverter that converts DC power into three-phase AC power, and a three-phase induction motor that is driven by the AC power converted by the inverter. There is an abnormality in the motor drive unit, a current abnormality detection unit that detects a current abnormality when the value of the current flowing through the inverter exceeds a predetermined threshold value, and a current abnormality detected periodically And a motor abnormality diagnosis unit that diagnoses the above.

  According to the motor control system of the present invention, the abnormality of the motor drive unit is diagnosed not from the current abnormality duration but from the periodicity of the current abnormality. The abnormality diagnosis accuracy of the unit can be improved.

FIG. 1 is a block diagram showing the overall configuration of the motor control system according to the first embodiment of the present invention. FIG. 2 is a flowchart showing an example of the flow of arithmetic processing performed by the abnormality processing unit 6 of FIG. FIG. 3 is a graph showing a case where current abnormality is determined to have periodicity from the comparison between the alternating current (AC) component of the current detected by the shunt resistor 8 and the first threshold value. FIG. 4 is a graph showing a case where it is determined that the current abnormality has no periodicity from the comparison between the alternating current (AC) component of the current detected by the shunt resistor 8 and the first threshold value. FIG. 5 is a block diagram showing the overall configuration of the motor control system according to the second embodiment of the present invention. FIG. 6 is a flowchart illustrating an example of a flow of arithmetic processing performed by the abnormality processing unit 6 of FIG. FIG. 7 is a graph showing a case where current abnormality is diagnosed as having periodicity based on the comparison between the sum of three-phase alternating current values and the upper threshold value and the lower threshold value. FIG. 8 is a graph showing a case where it is diagnosed that there is no periodicity in the current abnormality from the comparison between the sum of the three-phase alternating current values and the upper threshold value and the lower threshold value. FIG. 9 is a block diagram showing the overall configuration of a motor control system according to the third embodiment of the present invention. FIG. 10 is a flowchart illustrating an example of the flow of arithmetic processing performed by the abnormality processing unit 6 of FIG. FIG. 11 is a block diagram illustrating a configuration example of the abnormality processing unit 6 that executes the processing of the subroutine A in FIG. 10. FIG. 12 is a flowchart showing the subroutine A of FIG. FIG. 13 is a diagram for explaining the problems of the prior art.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals.

(First embodiment)
First, the overall configuration of the motor control system according to the first embodiment of the present invention will be described with reference to FIG. The motor control system according to the first embodiment includes a battery 2 that supplies DC power, an inverter 4 that converts DC power into three-phase AC power, and a three-phase drive driven by the AC power converted by the inverter 4. A motor drive unit 22 having an induction motor 1, a current abnormality detection unit (first current abnormality detection unit 23a) for detecting a current abnormality when a current value flowing through the inverter 4 exceeds a predetermined threshold value, a current An abnormality processing unit (motor abnormality diagnosis unit) 6 that diagnoses that the motor drive unit 22 has an abnormality when abnormality is periodically detected is provided.

  Here, the “abnormality occurring in the motor drive unit 22” diagnosed by the abnormality processing unit 6 includes three AC wirings for transmitting three-phase AC power input from the inverter 4 to the three-phase induction motor 1, or a battery. 2 includes disconnection of DC wiring for transmitting DC power input from 2 to the inverter 4, AC wiring or DC wiring, and connection failure between the inverter 4, the three-phase induction motor 1 or the battery 2.

  Further, the “current value flowing through the inverter 4” includes a direct current value input to the inverter 4 and an alternating current value output from the inverter 4. In the first embodiment, a case where the “current value flowing through the inverter 4” is a direct current value input to the inverter 4 will be described.

  That is, as an example of the current abnormality detection unit, a first current abnormality detection unit 23a that detects a current abnormality when the DC current value input to the inverter 4 is equal to or greater than a first threshold value will be described. The abnormality processing unit 6 diagnoses that there is an abnormality in the motor drive unit 22 when a current abnormality is detected for each cycle of the electrical angle of the three-phase induction motor 1 (hereinafter simply referred to as “electrical angle”). To do.

  Specifically, the first current abnormality detection unit 23a includes a shunt resistor 8 as an example of a DC current detection unit that detects a DC current input to the inverter 4, and the DC current detected by the shunt resistor 8 is the first. A first comparison that outputs an abnormal signal indicating that there is a current abnormality when the current value is equal to or greater than the threshold value, and outputs a normal signal indicating that there is no current abnormality when the direct current is less than the first threshold value. Part 12.

  The abnormality processing unit 6 outputs a normal signal from the first current abnormality detection unit 23a and outputs the normal signal within one cycle of the electrical angle after the abnormality signal is output from the first current abnormality detection unit 23a. When the abnormal signal is output again from the first current abnormality detection unit 23a within one cycle of the electrical angle after the is output, the motor drive unit 22 is diagnosed as having an abnormality. When it is diagnosed that there is an abnormality in the motor drive unit 22, a motor abnormality signal ES is output to notify the user or the like.

  The arithmetic processing performed by the abnormality processing unit 6 can be performed using the CPU 5 provided in the computer by installing a computer program defining the arithmetic processing in the computer. The motor control system includes a stabilized power supply 3 that supplies power necessary for the CPU 5 to operate. Of course, the abnormality processing unit 6 can be implemented not only as software such as a computer program, but also as hardware such as an ASIC (application-specific integrated circuit) or FPGA (field programmable gate array).

  The inverter 4 converts DC power into three-phase AC power using a power switching element such as an IGBT. The shunt resistor 8 is connected in parallel to the battery 2 between the inverter 4 and the ground potential. The shunt resistor 8 is a sensor that detects a current flowing through the inverter 4, and the current detected by the shunt resistor 8 corresponds to the potential between the shunt resistor 8 and the inverter 4. The potential between the shunt resistor 8 and the inverter 4 is amplified by the amplifier circuit 9. Of the signal output from the amplifier circuit 9, the direct current (DC) component is removed by coupling by the capacitor 10, and only the alternating current (AC) component is extracted. The alternating current (AC) component is amplified by the amplifier circuit 11 and then input to one input terminal of the first comparison unit 12 as a signal SGa. A reference power supply 13 is connected to the other input terminal of the first comparison unit 12, and a reference voltage output from the reference power supply 13 is input to the other input terminal.

  The first comparison unit 12 compares the potential of the signal SGa with a reference voltage. When the potential of the signal SGa is equal to or higher than the reference voltage, the first comparison unit 12 determines that the direct current detected by the shunt resistor 8 is equal to or higher than the first threshold value, and determines the H level signal (abnormal signal). ) Is output. When the potential of the signal SGa is less than the reference voltage, the first comparison unit 12 determines that the direct current detected by the shunt resistor 8 is less than the first threshold, and the L level signal (normal signal) ) Is output. The H level signal and the L level signal are input to the CPU 5.

  The CPU 5 has a function as a control unit 7 that performs PWM control of the three-phase induction motor 1. The control unit 7 generates a signal indicating the current rotational speed RC of the three-phase induction motor 1 and a signal indicating the magnitude of the load applied to the three-phase induction motor 1 or a signal indicating the rotational speed necessary for the three-phase induction motor 1. Based on this, the torque of the three-phase induction motor 1 is calculated, and a switching signal DS for realizing the motor current necessary for generating the torque is output to the inverter 4.

  Next, an example of the flow of arithmetic processing executed by the CPU 5 of FIG. 1 as the abnormality processing unit 6 will be described with reference to the flowchart of FIG. First, in step S01, it is determined whether or not an H level signal is input from the first current abnormality detector 23a. When the L level signal is detected and the H level signal is not detected, it can be diagnosed that the motor drive unit 22 is normal. Therefore, in step S01, the input of the H level signal is monitored.

  When the H level signal is detected (YES in S01), the process proceeds to step S03, and it is determined whether or not the L level signal is detected within one cycle of the electrical angle after the H level signal starts to be detected. If the L level signal is detected within one cycle of the electrical angle (YES in S03), the process proceeds to step S05 and whether the H level signal is detected again within one cycle of the electrical angle after starting to detect the L level signal. Judge whether or not. When the H level signal is detected again (YES in S05), since the detection of the H level signal is periodic, it can be determined that there is an abnormality in the motor drive unit 22, so the process proceeds to step S07 and the motor abnormality signal ES is output. To do.

  On the other hand, if the H level signal is not detected again within one cycle of the electrical angle (NO in S05), since there is no periodicity in the detection of the H level signal, it cannot be determined that there is an abnormality in the motor drive unit 22. Return to.

  Further, when the L level signal is not detected within one cycle of the electrical angle from the start of detecting the H level signal (NO in S03), the state where the DC current value input to the inverter 4 is high continues for one cycle or more of the electrical angle. Therefore, since it can be determined that there is an abnormality in the motor drive unit 22, the process proceeds to step S07 and a motor abnormality signal ES is output.

  The graph of FIG. 3 shows a case where the current abnormality has periodicity from the comparison between the first threshold value and the alternating current (AC) component extracted by the capacitor 10 in the current detected by the shunt resistor 8. In the alternating current (AC) component, a current peak value appears for each period of the electrical angle. If the current peak value is less than the first threshold value, the CPU 5 detects an L level signal in the vicinity of the current peak value. On the other hand, as shown in FIG. 3, when the current peak value is equal to or higher than the first threshold value, the CPU 5 detects an H level signal indicating a current abnormality in the vicinity of the current peak value.

  Thereafter, since the alternating current (AC) component becomes less than the first threshold value, the CPU 5 detects the L level signal. Further, in the next cycle, when the current peak value becomes equal to or higher than the first threshold value, the CPU 5 again detects an H level signal indicating a current abnormality in the vicinity of the current peak value.

  In the case shown in FIG. 3, the abnormality processing unit 6 of the CPU 5 detects the L level signal within one cycle of the electrical angle after detecting the H level signal and detects the L level signal and then detects the electrical angle. The H level signal is detected again within one cycle. Therefore, since periodicity is recognized in the current abnormality, it is diagnosed that the motor drive unit 22 is abnormal.

  On the other hand, the graph of FIG. 4 shows a case where there is no periodicity in the current abnormality from the comparison between the alternating current (AC) component taken out by the capacitor 10 of the current detected by the shunt resistor 8 and the first threshold value. Show. Here, the case where the electrical noise NS is added to the current peak value in a specific period is illustrated. Although the current peak value itself included in the alternating current (AC) component is less than the first threshold value, an electrical noise NS is added thereto, whereby the current peak value including the noise NS is the first peak value. It becomes more than the threshold.

  In the case shown in FIG. 4, the CPU 5 detects an H level signal indicating a current abnormality in the vicinity of the current peak value in a specific cycle in which the noise NS is added in the same manner as in FIG. Since the component is less than the first threshold value, the CPU 5 detects the L level signal. However, since the current peak value is less than the first threshold value in the next cycle, the CPU 5 does not detect the H level signal and continues to detect the L level signal in the vicinity of the current peak value.

  In the case shown in FIG. 4, the abnormality processing unit 6 of the CPU 5 detects the L level signal within one cycle of the electrical angle after detecting the H level signal. The H level signal is not detected again within one cycle. Therefore, since periodicity is not recognized in the current abnormality, it is not determined that the motor drive unit 22 is abnormal.

  As described above, according to the first embodiment of the present invention, the following operational effects can be obtained.

  When an abnormality occurs in the motor drive unit 22, there is a characteristic that periodicity occurs in the current abnormality. Using this characteristic, the abnormality of the motor drive unit 22 is diagnosed not from the duration of the current abnormality but from the periodicity of the current abnormality. That is, the abnormality processing unit 6 of the CPU 5 detects the L level signal within one cycle of the electrical angle after detecting the H level signal, and within one cycle of the electrical angle after detecting the L level signal. When the H level signal is detected again, since periodicity is recognized in the current abnormality, it is diagnosed that the motor drive unit 22 is abnormal. Thereby, the noise NS without periodicity and the abnormality of the motor drive unit 22 can be identified with high accuracy, and the abnormality diagnosis accuracy of the motor drive unit 22 can be improved.

  The first current abnormality detection unit 23a detects a current abnormality when the direct current input to the inverter 4 is equal to or greater than the first threshold value. The abnormality processing unit 6 diagnoses that the motor drive unit 22 is abnormal when a current abnormality is detected for each cycle of the electrical angle of the three-phase induction motor 1. A direct current input from the battery 2 to the inverter 4 is detected, and an abnormality of the motor drive unit 22 is diagnosed based on the detected direct current. For this reason, since the electric current detected compared with an alternating current is stable, diagnostic accuracy improves.

  Thus, the first current abnormality detection unit 23a detects a current abnormality when the value of the current flowing through the inverter 4 exceeds a predetermined threshold value. The abnormality processing unit 6 diagnoses that there is an abnormality in the motor drive unit 22 when current abnormality is periodically detected. The abnormality of the motor drive unit can be accurately diagnosed from the periodicity of the current abnormality.

(Second Embodiment)
In the second embodiment, a case where the “current value flowing through the inverter 4” is an alternating current output from the inverter 4 will be described.

  The sum of the three-phase alternating current values output from the inverter 4 is theoretically 0A. However, when an abnormality occurs in the output of the current sensor due to a gain failure of the current sensor that detects the alternating current, the sum of the three-phase alternating current values does not become 0A, but a sine wave centered on 0A is formed. Therefore, when there is an abnormality in the output of the current sensor, an abnormality in the motor drive unit 22 is detected by utilizing the fact that the peak value of the sum of the three-phase alternating current values is increased.

  First, the overall configuration of a motor control system according to the second embodiment of the present invention will be described with reference to FIG. In the motor control system according to the second embodiment, the second current abnormality detection unit 23b, which is another example of the current abnormality detection unit, is configured such that the sum of the three-phase AC current values output from the inverter 4 is the upper side. When it is equal to or greater than the threshold value (second threshold value) or less than the lower threshold value (third threshold value) smaller than the upper threshold value (second threshold value) Detect current anomalies. The abnormality processing unit 6 diagnoses that there is an abnormality in the motor drive unit 22 when a current abnormality is detected every half cycle of the electrical angle.

  Specifically, the second current abnormality detection unit 23b includes a current sensor 20 that detects a three-phase alternating current value output from the inverter 4, and a sum of the three-phase alternating current values detected by the current sensor 20. And a second comparison unit 21 that compares the sum of the three-phase alternating current values with the second and third threshold values. Specifically, each of the three-phase alternating current values detected by the current sensor 20 is an analog signal. The analog signals indicating the three-phase alternating current values detected by the current sensor 20 are converted into digital signals indicating the three-phase alternating current values in the A / D unit 19, respectively. The three-phase sum calculation unit 18 receives the three-phase alternating current value converted into a digital signal by the A / D unit 19.

  The second comparison unit 21 outputs an upper abnormality signal indicating that there is a current abnormality when the sum of the alternating current values calculated by the three-phase sum calculation unit 18 is equal to or greater than the upper threshold value, and A normal signal indicating that there is no current abnormality is output when the sum is greater than or equal to the lower threshold and less than the upper threshold, and there is current abnormality when the sum of the alternating current values is less than the lower threshold. The lower normal signal indicating is output. The upper abnormal signal, the normal signal, and the lower normal signal output from the second comparison unit 21 are respectively input to the abnormality processing unit 6.

  It is desirable that the upper threshold value and the lower threshold value have different signs and have the same absolute value. Since the sum of three-phase alternating current values forms a sine wave centered at 0 A, when the motor drive unit 22 is abnormal, the upper abnormal signal and the lower abnormal signal are detected alternately every half cycle. Can do.

  The abnormality processing unit 6 outputs a normal signal within a half cycle of the electrical angle after the output of the upper abnormal signal or the lower abnormal signal, and falls within a half cycle of the electrical angle after the normal signal is output. When the side abnormality signal or the upper side abnormality signal is output, the motor drive unit 22 is diagnosed as having an abnormality. When diagnosing that there is an abnormality in the motor drive unit 22, a motor abnormality signal ES is output to notify the user.

  The arithmetic processing performed by each of the A / D unit 19, the three-phase sum calculation unit 18, and the abnormality processing unit 6 is performed using the CPU 5 of the computer by installing a computer program that defines the arithmetic processing in the computer. can do. Of course, the A / D unit 19, the three-phase sum calculation unit 18, and the abnormality processing unit 6 can be implemented not only as software such as a computer program but also as hardware such as an ASIC or FPGA. Other configurations are the same as those in FIG.

  Next, an example of the flow of arithmetic processing executed by the CPU 5 of FIG. 5 as the abnormality processing unit 6 will be described with reference to the flowchart of FIG. First, in step S11, it is determined whether or not an H level signal (upper side abnormal signal) is input from the second current abnormality detection unit 23b. When the M level signal (normal signal) is detected and the H level signal (upper abnormal signal) and the L level signal (lower abnormal signal) are not detected, it can be diagnosed that the motor drive unit 22 is normal. In step S01, the input of the H level signal is monitored.

  When the H level signal is detected (YES in S11), the process proceeds to step S13, and it is determined whether or not the M level signal is detected within a half cycle of the electrical angle after starting to detect the H level signal. If the M level signal is detected within the half cycle of the electrical angle (YES in S13), the process proceeds to step S15, and the L level signal is detected within every half cycle of the electrical angle after starting to detect the M level signal. Judge whether or not. When the L level signal is detected (YES in S15), since the detection of the H level signal or the L level signal indicating that there is a current abnormality is periodic, it can be determined that the motor drive unit 22 is abnormal. Proceed to the stage and output the motor abnormality signal ES.

  On the other hand, when the L level signal is not detected within every half cycle of the electrical angle (NO in S15), the motor drive unit 22 has no periodicity in detecting the H level signal or L level signal indicating that there is a current abnormality. Since it cannot be determined that there is an abnormality, the process returns to step S11.

  In addition, when the M level signal is not detected within a half cycle of the electrical angle after the start of the detection of the H level signal (NO in S13), the state where the sum of the three-phase alternating current values is high continues for a half cycle or more of the electrical angle. Therefore, since it can be determined that there is an abnormality in the motor drive unit 22, the process proceeds to step S17, and the motor abnormality signal ES is output.

  In the example shown in FIG. 6, the operation example when the H level signal is first detected in the S01 stage is shown. However, the present invention is not limited to this, and the abnormality processing unit 6 performs the same operation as in FIG. 6 by replacing the H level signal and the L level signal in FIG. By doing so, abnormality of the motor drive unit 22 can be diagnosed.

  The graph of FIG. 7 shows a case where current abnormality is diagnosed as having periodicity from the comparison between the sum of three-phase alternating current values and the upper threshold value and the lower threshold value. When the current sensor 20 is abnormal, the sum of the three-phase alternating current values forms a sine wave centered on 0A. In the sine wave, a current peak value, that is, a maximum value or a minimum value appears every half cycle of the electrical angle. If the maximum value is less than the upper threshold value, the CPU 5 detects the M level signal in the vicinity of the maximum value. On the other hand, as shown in FIG. 7, when the maximum value is equal to or greater than the upper threshold value, the CPU 5 detects an H level signal indicating a current abnormality in the vicinity of the maximum value. Thereafter, since the sum of the three-phase alternating current values becomes less than the upper threshold value, the CPU 5 detects the M level signal. After that, if the minimum value is equal to or greater than the lower threshold value after a half cycle, the CPU 5 detects the M level signal in the vicinity of the minimum value. On the other hand, as shown in FIG. 7, when the minimum value is less than the lower threshold value, the CPU 5 detects an L level signal indicating a current abnormality in the vicinity of the minimum value.

  In the case of FIG. 7, the abnormality processing unit 6 of the CPU 5 detects the M level signal within the half cycle of the electrical angle after detecting the H level signal, and detects the M level signal after detecting the M level signal. Within the period, the L level signal is detected. Therefore, since periodicity is recognized in the current abnormality, it is diagnosed that the motor drive unit 22 is abnormal.

  On the other hand, the graph of FIG. 8 shows a case where it is diagnosed that there is no periodicity in the current abnormality from the comparison between the sum of the three-phase alternating current values and the upper threshold value and the lower threshold value. Here, the case where the electrical noise NS is added to the maximum value in a specific period is illustrated. The maximum value itself in the sum of the three-phase alternating current values is less than the upper threshold value. However, when the electrical noise NS is added thereto, the maximum value including the noise NS is more than the upper threshold value. turn into.

  In the case illustrated in FIG. 8, the CPU 5 detects an H level signal indicating a current abnormality in the vicinity of the maximum value in a specific cycle in which the noise NS is added in the same manner as in FIG. Since the sum of the values is less than the upper threshold value, the CPU 5 detects the M level signal. However, since the minimum value is equal to or greater than the lower threshold value in the same cycle, the CPU 5 does not detect the L level signal and continues to detect the M level signal in the vicinity of the minimum value.

  In the case shown in FIG. 8, the abnormality processing unit 6 of the CPU 5 detects the M level signal within a half cycle of the electrical angle after detecting the H level signal. The L level signal is not detected within every half cycle. Therefore, since periodicity is not recognized in the current abnormality, it is not determined that the motor drive unit 22 is abnormal.

  As described above, according to the second embodiment of the present invention, the following operational effects can be obtained.

  The abnormality processing unit 6 of the CPU 5 detects the M level signal within a half cycle of the electrical angle after detecting the H level signal or the L level signal, and detects the M level signal and then the half cycle of the electrical angle. When the L level signal or the H level signal is detected within the period, periodicity is recognized in the current abnormality, so that the motor drive unit 22 is diagnosed as having an abnormality. Thereby, the noise NS without periodicity and the abnormality of the motor drive unit 22 can be identified with high accuracy, and the abnormality diagnosis accuracy of the motor drive unit 22 can be improved.

  The second current abnormality detection unit 23b detects a current abnormality when the sum of the three-phase alternating current values output from the inverter 4 is equal to or greater than the upper threshold value or less than the lower threshold value. To do. The abnormality processing unit 6 diagnoses that the motor drive unit 22 is abnormal when a current abnormality is detected every half cycle of the electrical angle of the three-phase induction motor 1. As a result, the detection cycle is shortened to approximately half compared to the current abnormality detected every cycle, and in addition to improving the diagnostic accuracy, the diagnostic speed is increased.

(Third embodiment)
In the third embodiment, a motor control system for diagnosing an abnormality of the motor drive unit 22 by selecting an appropriate diagnosis method according to a diagnosis request time required for diagnosing the abnormality of the motor drive unit 22 Will be described.

  The motor control system according to the third embodiment corresponds to a system in which the motor control system according to the first embodiment and the motor control system according to the second embodiment are combined. That is, as shown in FIG. 9, the motor control system includes a battery 2 that supplies DC power, an inverter 4 that converts DC power into three-phase AC power, and three drives driven by AC power converted by the inverter 4. A motor drive unit having the phase induction motor 1, a first current abnormality detection unit 23 a that detects a current abnormality when the direct current input to the inverter 4 is equal to or greater than the first threshold value, and an output from the inverter 4. When the sum of the three-phase alternating current values is greater than or equal to the upper threshold value (second threshold value) or less than the lower threshold value (third threshold value), A second current abnormality detecting unit 23b for detecting, and an abnormality processing unit (motor abnormality diagnosing unit) 6 for diagnosing an abnormality in the motor drive unit when current abnormality is periodically detected.

  Further, the CPU 5 has a function as a request time determination unit 24 that determines a diagnosis request time required for diagnosing abnormality of the motor drive unit. The request time determination unit 24 receives a signal MT indicating a diagnosis request time transmitted from a host control unit (not shown), and determines the diagnosis request time based on the signal MT. When the diagnosis request time determined by the request time determination unit 24 is equal to or longer than a half cycle of the electrical angle, the abnormality processing unit 6 determines whether the current abnormality is periodically detected or not. Diagnose the abnormality. On the other hand, when the diagnosis request time determined by the request time determination unit 24 is less than a half cycle of the electrical angle, the abnormality processing unit 6 diagnoses the abnormality of the motor drive unit 22 based on the time during which the current abnormality continues. . A method for diagnosing an abnormality of the motor drive unit 22 based on the time during which the current abnormality continues will be described later with reference to FIGS. 11 and 12.

  Further, when the diagnosis request time determined by the request time determination unit 24 is equal to or greater than a half cycle of the electrical angle and less than one cycle of the electrical angle, the second current abnormality detection unit 23b outputs from the inverter 4 The current abnormality is detected when the sum of the three-phase alternating current values is equal to or higher than the upper threshold value or equal to or lower than the lower threshold value. Then, the abnormality processing unit 6 diagnoses that there is an abnormality in the motor drive unit 22 when a current abnormality is detected every half cycle of the electrical angle.

  In the case where the diagnosis request time determined by the request time determination unit 24 is one cycle or more of the electrical angle, the first current abnormality detection unit 23a has the DC current input to the inverter 4 equal to or greater than the first threshold value. Detect current anomalies when Then, the abnormality processing unit 6 diagnoses that there is an abnormality in the motor drive unit 22 when a current abnormality is detected for each cycle of the electrical angle.

  Other configurations are the same as those in FIG. 1 or FIG.

  Next, an example of the flow of arithmetic processing executed by the CPU 5 of FIG. 9 as the abnormality processing unit 6 will be described with reference to the flowchart of FIG. First, in step S21, it is determined whether the diagnosis request time is equal to or longer than a half cycle of the electrical angle. If it is equal to or longer than a half cycle of the electrical angle, the process proceeds to step S23. On the other hand, if the electrical angle is less than a half cycle, sufficient time cannot be obtained for accurately diagnosing the abnormality based on the periodicity of the current abnormality, and therefore the motor drive unit 22 is based on the time that the current abnormality continues. The process proceeds to the subroutine A for diagnosing the abnormality.

  In step S23, it is determined whether the diagnosis request time is one cycle or more of the electrical angle. When the diagnosis request time is one cycle or more of the electrical angle (YES in S23), the process proceeds to step S25, and in step S25 to S29, the periodicity of current abnormality is determined based on the direct current input to the inverter 4. . The processing operations in steps S25 to S29 are the same as those in steps S01 to S05 in FIG.

  On the other hand, when the diagnosis request time is less than one cycle of the electrical angle (NO in S23), the process proceeds to step S31, and in steps S31 to S35, based on the sum of the three-phase alternating current values output from the inverter 4, Determine the periodicity of current anomalies. The processing operations in steps S31 to S35 are the same as those in steps S11 to S15 in FIG.

  If the current abnormality is periodic (YES in S29, YES in S35), it can be determined that there is an abnormality in the motor drive unit 22. Therefore, the process proceeds to step S37, and the motor abnormality signal ES is output.

  FIG. 11 shows a configuration example of the abnormality processing unit 6 that executes the processing of the subroutine A of FIG. FIG. 12 is a flowchart showing the subroutine A of FIG. The abnormality processing unit 6 measures the H level time during which the H level signal is continuously output among the H level signal (abnormal signal) and the L level signal (normal signal) output from the first comparison unit 12. An abnormality determination time output unit 33 that outputs an abnormality determination time t according to a time RC-abnormality determination time t map MP indicating the relationship between the H-level time measurement unit 31 and the rotational speed RC of the three-phase induction motor and the abnormality determination time t. The third comparison unit 32 that compares the abnormality determination time t output from the abnormality determination time output unit 33 with the H level time measured by the H level time measurement unit 31, and the comparison by the third comparison unit 32 And a diagnosis result output unit 34 for outputting a diagnosis result based on the result.

  The abnormality determination time output unit 33 receives a signal indicating the rotational speed RC of the three-phase induction motor 1 and outputs an abnormality determination time t corresponding to the rotational speed RC according to the time RC-abnormality determination time t map MP. According to the time RC-abnormality determination time t map MP, the abnormality determination time t decreases as the rotational speed RC increases. The third comparison unit 32 determines whether or not the H level time is longer than the abnormality determination time t (S41). When the H level time is longer than the abnormality determination time t (YES in S41), the diagnosis result output unit 34 outputs a motor abnormality signal ES (S43). When the H level time is equal to or less than the abnormality determination time t (NO in S41), the diagnosis result output unit 34 outputs the motor normal signal FS (S45).

  As described above, according to the third embodiment of the present invention, the following operational effects can be obtained.

  When the diagnosis request time is equal to or longer than a half cycle of the electrical angle, the abnormality processing unit 6 diagnoses an abnormality of the motor drive unit 22 according to whether or not a current abnormality is periodically detected. When the diagnosis request time is less than a half cycle of the electrical angle, the abnormality processing unit 6 diagnoses the abnormality of the motor drive unit 22 based on the time during which the current abnormality continues. As described above, according to the diagnosis request time determined by the request time determination unit 24, the abnormality processing unit 6 diagnoses the abnormality of the motor drive unit 22 based on the periodicity of the current abnormality or the time during which the current abnormality continues. To do. Thus, an appropriate abnormality diagnosis method can be selected according to the time required for diagnosis while improving diagnosis accuracy.

  Further, when diagnosing an abnormality of the motor drive unit 22 based on the periodicity of the current abnormality, if the diagnosis request time is equal to or greater than a half period of the electrical angle and less than one period of the electrical angle, the abnormality processing unit 6 Diagnoses the abnormality of the motor drive unit 22 based on the periodicity of the current abnormality that occurs in the sum of the three-phase alternating current values output from the inverter 4. On the other hand, when the diagnosis request time is one cycle or more of the electrical angle, the abnormality processing unit 6 diagnoses the abnormality of the motor drive unit 22 based on the periodicity of the current abnormality generated in the direct current input to the inverter 4. To do. Thus, an appropriate diagnosis method can be selected according to the time required for diagnosis, and an abnormality of the motor drive unit 22 can be diagnosed with high accuracy.

  Of course, when the diagnostic method corresponding to the first embodiment or the second embodiment is selected, the same effects as described in the first embodiment and the second embodiment can be obtained. .

  As described above, the present invention has been described according to the first to third embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

DESCRIPTION OF SYMBOLS 1 ... Three-phase induction motor 2 ... Battery 4 ... Inverter 6 ... Abnormal processing part (motor abnormality diagnostic part)
8 ... Shunt resistor (DC current detector)
DESCRIPTION OF SYMBOLS 12 ... 1st comparison part 18 ... Three-phase sum calculation part 20 ... Current sensor 21 ... 2nd comparison part 22 ... Motor drive unit 23a ... 1st current abnormality detection part (current abnormality detection part)
23b ... second current abnormality detection unit (current abnormality detection unit)
24: Request time determination unit

Claims (7)

A motor drive unit including an inverter that converts DC power into three-phase AC power, and a three-phase induction motor that is driven by the AC power converted by the inverter;
A current abnormality detector for detecting a current abnormality when a current value flowing through the inverter exceeds a predetermined threshold;
And a motor abnormality diagnosis unit that diagnoses that the motor drive unit is abnormal when the current abnormality is periodically detected. The current abnormality detection unit detects a current abnormality when a direct current input to the inverter is equal to or greater than a first threshold value,
The motor abnormality diagnosis unit diagnoses that there is an abnormality in the motor drive unit when the current abnormality is detected every cycle of the electrical angle of the three-phase induction motor. The motor control system described. The current abnormality detector is
A direct current detector for detecting a direct current input to the inverter;
When the direct current detected by the direct current detector is greater than or equal to the first threshold value, an abnormality signal indicating that the current abnormality is present is output, and the direct current is less than the first threshold value. A first comparison unit that outputs a normal signal indicating that there is no current abnormality at a certain time, and
The motor abnormality diagnosis unit outputs a normal signal within one cycle of the electrical angle after the output of the abnormal signal, and again outputs an abnormal signal within one cycle of the electrical angle after the normal signal is output. The motor control system according to claim 2, wherein a diagnosis is made that there is an abnormality in the motor drive unit. The current abnormality detector is configured to output a third signal when the sum of the three-phase alternating current values output from the inverter is equal to or greater than a second threshold value or smaller than the second threshold value. Detect current anomalies when the threshold is less than
The motor abnormality diagnosis unit diagnoses that there is an abnormality in the motor drive unit when the current abnormality is detected every half cycle of the electrical angle of the three-phase induction motor. The motor control system described. The current abnormality detector is
A current sensor for detecting a three-phase alternating current value output from the inverter;
A three-phase sum calculator for calculating the sum of three-phase alternating current values detected by the current sensor;
When the sum of the alternating current values calculated by the three-phase sum calculation unit is equal to or greater than the second threshold value, an upper abnormality signal indicating that the current abnormality is present is output, and the sum of the alternating current values is A normal signal indicating that there is no current abnormality is output when the current is not less than a third threshold and less than the second threshold, and the sum of the alternating current values is less than the third threshold. A second comparator that outputs a lower normal signal that sometimes indicates that there is an abnormality in the current,
The motor abnormality diagnosing unit outputs a normal signal within a half cycle of the electrical angle from the output of the upper side abnormal signal or the lower side abnormal signal, and the half cycle of the electrical angle after the normal signal is output. 5. The motor control system according to claim 4, wherein the motor drive unit is diagnosed as having an abnormality when a lower abnormality signal or an upper abnormality signal is output within 5 minutes. A request time determination unit for determining a diagnosis request time required for diagnosing abnormality of the motor drive unit;
When the diagnosis request time determined by the request time determination unit is equal to or greater than a half cycle of the electrical angle of the three-phase induction motor, the motor abnormality diagnosis unit determines whether the current abnormality is periodically detected. According to the diagnosis of abnormality of the motor drive unit,
When the diagnosis request time determined by the request time determination unit is less than a half cycle of the electrical angle of the three-phase induction motor, the motor abnormality diagnosis unit drives the motor based on the time that the current abnormality continues. The motor control system according to any one of claims 1 to 5, wherein an abnormality of the unit is diagnosed. A request time determination unit for determining a diagnosis request time required for diagnosing abnormality of the motor drive unit;
In the case where the diagnosis request time determined by the request time determination unit is not less than a half cycle of the electrical angle of the three-phase induction motor and less than one cycle of the electrical angle,
The current abnormality detector is configured to output a third signal when the sum of the three-phase alternating current values output from the inverter is equal to or greater than a second threshold value or smaller than the second threshold value. Detect current anomaly when below threshold,
The motor abnormality diagnosis unit diagnoses that there is an abnormality in the motor drive unit when the current abnormality is detected every half cycle of the electrical angle,
In the case where the diagnosis request time determined by the request time determination unit is one cycle or more of the electrical angle,
The current abnormality detection unit detects a current abnormality when a direct current input to the inverter is equal to or greater than a first threshold value,
The motor control system according to claim 1, wherein the motor abnormality diagnosis unit diagnoses that the motor drive unit is abnormal when the current abnormality is detected for each cycle of the electrical angle. .

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