JP7278231B2 - Motor drive device and state detection method - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to an electric motor drive device and a state detection method.

A motor drive device controls a plurality of single-phase inverters to drive an AC motor having a plurality of mutually independent single-phase windings. Each single-phase inverter is provided in association with each single-phase winding, and independently controls the current flowing through the single-phase winding. Even if the electric motor driving device controls the single-phase inverters so that they output equal drive amounts, the drive amounts of the inverters may not match. When the AC motor is driven in such a situation, an abnormal state such as increased vibration of the AC motor may occur.

JP 2015-104235 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor drive device and a state detection method that can further improve the reliability when driving an AC motor.

An electric motor drive device according to an embodiment includes a drive amount command section, an integrator, and a determination section. The driving amount command unit sends commands to a plurality of single-phase inverters for supplying current to each single-phase winding of an AC motor having a plurality of independent single-phase windings. The integrating unit integrates measured values of a first current flowing through a first single-phase winding of the plurality of single-phase windings at predetermined intervals to generate a first integrated value, Measured values of the second current flowing through the second single-phase winding of the windings are integrated at the predetermined intervals to generate a second integrated value. The integrating section sets an integration period of the first integrated value and the second integrated value to be constant, and calculates the first integrated value and the second integrated value by a moving average of the integrated period. The determination unit determines states of the plurality of single-phase inverters based on the first integrated value and the second integrated value.

1 is a schematic configuration diagram of an electric motor drive device according to an embodiment; FIG. The block diagram of the electric-motor drive device of embodiment. FIG. 4 is a conceptual diagram for explaining differences in current values of single-phase windings according to the embodiment; 4 is a flowchart of abnormal state detection processing according to the embodiment; The figure for demonstrating the abnormal state detection process of embodiment. The schematic block diagram of the electric-motor drive device of a modification.

Hereinafter, an electric motor drive device and a state detection method according to embodiments will be described with reference to the drawings.
In addition, in the following description, the same code|symbol is attached|subjected to the structure which has the same or similar function. Duplicate descriptions of those configurations may be omitted. It should be noted that being electrically connected is sometimes simply referred to as being “connected”. "Single-phase pulse width modulation" in the following description means pulse width modulation for outputting a single-phase alternating current, and is sometimes simply called PWM. A "measured value of current" used in the following description refers to an actual measured value of current, an index value indicating the actual magnitude of current, or an estimated value indicating the magnitude of current.

(embodiment)
FIG. 1 is a schematic configuration diagram of an electric motor drive device 1 according to an embodiment. A motor drive device 1 drives an AC motor 2 .

The AC motor 2 has a plurality of single-phase windings (not shown). The multiple single-phase windings are independent (insulated) from each other. Each single-phase winding is arranged at a position sequentially shifted by a predetermined angle in the rotating direction of the rotor (not shown) of the AC motor 2 . The alternating magnetic field generated from each single-phase winding forms a plurality of poles, which causes current to flow through each single-phase winding so as to generate a rotating magnetic field. The number of single-phase windings in the AC motor 2 shown in FIG. 1 is eight, for example.

The AC motor 2 is provided with a position detector 2A. The position detector 2</b>A detects the rotor position of the AC motor 2 and supplies a position detection signal Rp to the motor control section 4 .

The motor drive device 1 includes, for example, single-phase inverters 3-1 to 3-8 and a motor control section 4. As shown in FIG.

The single-phase inverters 3-1 to 3-8 are provided in association with the single-phase windings of the AC motor 2, and the electric motor controller 4 controls the single-phase windings to apply currents to the single-phase windings. The single-phase inverters 3-1 to 3-8 supply the detection result of the current value to the motor control section 4, respectively. Single-phase inverters 3-1 to 3-8 are examples of a plurality of single-phase inverters. The single-phase inverters 3-1 to 3-8 may be collectively called a single-phase inverter 3.

A more specific example of the electric motor drive device 1 according to the embodiment will be described with reference to FIG. 2 . FIG. 2 is a configuration diagram of the electric motor drive device 1 of the embodiment.

The single-phase inverter 3-1 includes, for example, a main circuit 31, a current detection section 32, and a current control section 33.

The main circuit 31 includes a plurality of semiconductor switches, and converts DC power into AC power by switching to output single-phase AC power. The current detector 32 detects current flowing from the output terminal of the main circuit 31 to the single-phase winding of the AC motor 2 and generates a current detection value IFBK1. The current detection value IFBK1 is, for example, a value indicating the amplitude (magnitude) of the current flowing from the output terminal of the main circuit 31 to the single-phase winding of the AC motor 2 . The current control unit 33 performs PWM control, for example. For example, the current control unit 33 detects the current so that the single-phase AC current I1 corresponding to the current reference Ir1 supplied from the motor control unit 4 is caused to flow through the single-phase winding corresponding to the single-phase inverter 3-1. The value IFBK1 is used to control the main circuit 31 . The current control unit 33 may individually perform position control (rotational angle control) or speed control (rotational speed control) of the rotor of the AC motor 2 based on the position detection signal Rp.

The single-phase inverters 3-2 to 3-8 are also configured in the same manner as the single-phase inverter 3-1. The single-phase inverters 3-1 to 3-8, for example, individually perform PWM control. The single-phase inverters 3-1 to 3-8 pass single-phase AC currents I1 to I8 corresponding to the current references Ir1 to Ir8 through the corresponding single-phase windings to generate a rotating magnetic field in the AC motor 2 to generate alternating current. The rotor of the electric motor 2 is rotated.

The electric motor control unit 4 includes, for example, a drive amount command unit 41, an integration unit 42, a determination unit 43, and a control unit body 44.

Drive amount command unit 41 generates current references Ir1 to Ir8 based on speed reference Nr given from host device 5 and position detection signal Rp from position detector 2A.

For example, the drive amount command unit 41 includes a speed conversion unit 41a, a subtractor 41b, and a command value generation unit 41c. The speed converter 41a calculates the rotor speed N of the AC motor 2 based on the position detection signal Rp from the position detector 2A. The subtractor 41b calculates the difference between the speed reference Nr given from the host device 5 and the rotor speed N, that is, the speed deviation ΔN. The command value generator 41c generates the current references Ir1 to Ir8 so as to eliminate the speed deviation ΔN. The current references Ir1 to Ir8 may have the same value or different values depending on conditions.

The drive amount command unit 41 supplies the current reference Ir1 to the single-phase inverter 3-1 together with the position detection signal Rp. The drive amount command unit 41 similarly supplies the current references Ir2 to Ir8 together with the position detection signal Rp to the corresponding single-phase inverters 3-2 to 3-8.

The integration unit 42 acquires the measured values IFBK1 to IFBK8 of the current of each single-phase winding of the AC motor 2 from each single-phase inverter 3 and integrates them at predetermined intervals over a predetermined period. For example, the integrating section 42 integrates the measured value IFBK1 of the alternating current I1 (first current) flowing through the first single-phase winding at predetermined intervals to generate a first integrated value. The integrator 42 similarly integrates the measured value IFBK2 of the alternating current I2 (second current) flowing through the second single-phase winding at predetermined intervals to generate a second integrated value. The integrating section 42 also integrates the detected values IFBK3 to IFBK8 of the respective alternating currents for the third to eighth windings.

The determination unit 43 determines the state of each single-phase inverter 3 using each integration result obtained by the integration unit 42 . The control unit main body 44 controls each unit of the motor control unit 4 and the operating state of each single-phase inverter 3 according to the determination result of the determination unit 43 .

For example, when the control unit body 44 detects that an abnormal state has occurred in the single-phase inverters 3-1 to 3-8 from the determination result of the determination unit 43, it controls the drive amount command unit 41 to control the drive amount. The current references Ir1 to Ir8 output by the command unit 41 are controlled. Thereby, the control part main body 44 can control the operating state of each single-phase inverter 3 . Alternatively, the control unit body 44 may control each of the single-phase inverters 3-1 to 3-8 to stop outputting the respective output currents when the above abnormal state is detected. .

Next, the electric motor drive device 1 will be described with a more specific example.
3A and 3B are conceptual diagrams showing differences in the currents of the single-phase windings of the embodiment.
FIG. 3(a) shows the distribution of the integrated value of the current of each phase during normal operation, and FIG. 3(b) shows the distribution of the integrated value of the current of each phase during the abnormal operation. The range (horizontal axis) shown in FIG. 3 indicates n phases (n is a natural number). It becomes 8 integrated values. In order to simplify the explanation, in the electric motor drive device 1, the current references Ir1 to Ir8 supplied by the drive amount command section 41 are controlled to be equal to each other and do not change throughout the integration period.

Even if the system of the motor drive device 1 is in a normal state, the magnitude of the current flowing through each single-phase winding may vary as shown in FIG. 3(a). However, the variation between the phases is relatively small with respect to the integrated value of each phase, and does not greatly affect the rotation of the AC motor 2 .

By the way, when an abnormal state occurs in the system of the motor drive device, the magnitude of the current flowing through each single-phase winding may have a relatively large variation with respect to the integrated value of each phase. Such an abnormal state may occur, for example, when the command value acquired by a specific single-phase inverter 3 differs from the command value acquired by other single-phase inverters 3 . Even in such an abnormal state, if each single-phase inverter 3 operates autonomously according to a command, the abnormality may not be detected by the abnormality detection function of each single-phase inverter 3 .

For example, when the above event occurs, the magnitude of the integrated value of the first current in the single-phase winding of a specific phase changes from the magnitude of the integrated value of the second current in the single-phase winding of the other phase. There may be deviations. The deviation of the magnitude of the integrated value of the first current from the magnitude of the integrated value of the second current means that the variation in the magnitude of the integrated value of the second current in each single-phase winding when the system is normal says something very different. If such a situation occurs, an influence such as an increase in vibration of the AC motor 2 may occur.

Therefore, the abnormal state detection processing for the above events will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a flowchart of abnormal state detection processing according to the embodiment. FIG. 5 is a diagram for explaining the abnormal state detection processing of the embodiment.

The integration unit 42 acquires the measured values IFBK1 to IFBK8 of the current of each single-phase winding of the AC motor 2 from each single-phase inverter 3 (step S10), and accumulates them at predetermined intervals over a predetermined period. are integrated to calculate an integrated value (step S11).

Here, in order to facilitate the determination process described later, the integrated value is normalized. For example, the integration unit 42 calculates the average value of the integrated values of the currents of the phases other than the phase to be determined (step S12), and calculates the average value of the integrated value of the currents of the phase to be determined and the average value. Each ratio is calculated (step S13). The phase to be determined is an example of a system to be determined.

The determination unit 43 determines the state of the single-phase inverter 3 to be determined using the ratio between the integrated value of the current of the phase to be determined and the average value. Specifically, the determination unit 43 determines whether or not the ratio to the average value is smaller than a predetermined threshold (step S14).

When the ratio to the average value is equal to or greater than a predetermined threshold value, the determining unit 43 determines that the phase to be determined is normal (step S15), and determines that the operation of that phase can be continued. (step S16) and the process proceeds to step S19.

If the ratio to the average value is smaller than a predetermined threshold value, the determination unit 43 determines that the phase to be determined is abnormal (step S17), and stops the operation of that phase ( Step S18), and the process proceeds to step S19.

After completing the processing of step S16 or step S18, the control unit main body 44 determines whether or not all the phases have been determined (step S19). Proceeding to step S12, the undetermined phase is determined. When all the phases have been determined, the control unit main body 44 outputs the determination result (step S20) and finishes the process.

The electric motor drive device 1 detects an abnormal state that has occurred in the system of the electric motor drive device 1, for example, using the procedure of the abnormal state detection process described above.

By the way, while the motor driving device 1 is operating the AC motor 2, current flows through the windings. Since each integrated value by the integrating section 42 changes accordingly, it is not easy to directly determine the integrated value. On the other hand, the ratio between the average value of each integrated value and each integrated value does not change significantly unless there is an abnormality. In this embodiment, the state of each phase is detected using the ratio between the average value of each integrated value and each integrated value.

For example, in FIG. 5, when an open phase occurs in a specific phase and the current value of that phase is no longer detected, the integrated value of that phase is indicated by a dashed line. The integrated value based on the current values of the phases in the healthy state changes with time. Their average values also change over time. Since the vertical axis in FIG. 5 indicates the normalized value based on the average value, the value on the vertical axis becomes 100% even after the passage of time.

On the other hand, the integrated value of the phase in which the open phase has occurred does not change after the open phase has occurred. Therefore, when normalized using a changing average value, the value decreases with the passage of time.

If an open phase occurs 1 hour after the start of integration, the ratio of the integrated value of the phase where the open phase has occurred will gradually decrease after the open phase, and 2 hours after the start of integration down to 50%. For example, when 50% is used as the threshold, the determination unit 43 can determine that there is an abnormality in the phase in which the integrated value has decreased to 50%.

It should be noted that the integration unit 42 may subject some phases of the plurality of phases to integration. In this case, the integrator 42 integrates the current values of the plurality of target phases by, for example, the same method as described above for each phase to calculate the first integrated value and the second integrated value. The above-mentioned first integrated value is the integrated value of any one of the plurality of phases targeted for integration, and the second integrated value is any of the above-mentioned phases out of the plurality of phases targeted for integration. It is the integrated value of a specific phase other than the phase specified as the phase of

The length of the common predetermined period (accumulation period), the timing to start integration, and the timing to end integration may be determined as appropriate according to how the AC motor 2 is driven.

The shorter the elapsed time from the start of integration until the occurrence of an abnormality, the more abrupt the change in the integrated value of the current value of the phase due to the occurrence of the abnormality. This reduces the time required to detect the abnormal phase.

For example, when the integration period has a predetermined length, the integration unit 42 sets the time width of the integration period to a fixed value (constant), and calculates the first integrated value and the second integrated value of the integration period. can be calculated. A moving average calculation method may be applied to this calculation method.

Alternatively, the integration unit 42 may integrate over an integration period determined according to the magnitude of the mechanical load driven by the AC motor 2 . For example, if the fluctuation of the mechanical load is relatively large, the accumulation period is lengthened, and if the fluctuation of the mechanical load is relatively small, the accumulation period is shortened. It is possible to reduce erroneous detection caused by load fluctuations.

Next, initialization of the integrated value will be described. In order to detect an abnormality at an early stage, it is preferable to initialize the first integrated value and the second integrated value periodically with a relatively short period or at a predetermined timing. For example, the integrating section 42 may initialize the first integrated value and the second integrated value for each integration period defined as a common predetermined period. Alternatively, the integrating section 42 may initialize the first integrated value and the second integrated value in response to receiving a command to stop the operation of the AC motor 2 . Further, the integrating section 42 may initialize the first integrated value and the second integrated value with a period or timing determined according to the magnitude of the load on the AC motor 2 .

According to the above-described embodiment, the drive amount command unit 41 supplies a current to each of the single-phase windings of the AC motor 2 having a plurality of single-phase windings that are independent of each other. Send command to 8. The integrating unit 42 integrates the measured value IFBK1 of the current I1 flowing through the first single-phase winding among the plurality of single-phase windings at predetermined intervals to generate a first integrated value, Measured values IFBK2 to IFBK8 of the currents I2 to I8 flowing through the second single-phase windings are integrated at predetermined intervals to generate a second integrated value. The determination unit 43 determines the states of the single-phase inverters 3-1 to 3-8 based on the first integrated value and the second integrated value, thereby further increasing the reliability of driving the AC motor 2. can be done. The first integrated value and the second integrated value are examples of current integrated values.

The determination unit 43 can detect the states of the single-phase inverters 3-1 to 3-8 of each phase by suppressing the influence of the successive changes in each integrated value. Furthermore, as described above, the integrated value of the current of each single-phase winding varies, but by using the average value of the integrated current, the influence of the variation is suppressed and the state of each phase is detected. be able to.

(First modification)
The current flowing through each single-phase winding during acceleration and deceleration of the rotation speed of the AC motor 2 differs from a steady value. Therefore, this period may be excluded from evaluation targets.

For example, the drive amount command unit 41 detects the above acceleration and deceleration based on any of the speed reference Nr, the position detection signal Rp, and the rotor speed N, and selects the acceleration period or deceleration period. Alternatively, both are notified to the integrating section 42 and the determining section 43 . In response to this, the integrating section 42 may exclude either or both of the acceleration period and the deceleration period of the rotation speed of the AC motor 2 from the integration period. Similarly, the determination unit 43 may exclude either or both of the acceleration period and the deceleration period of the rotation speed of the AC motor 2 from the determination period. As a result, erroneous detection due to changes in the current value during acceleration and deceleration can be reduced.

(Second modification)
In the above embodiment, an example was explained in which an abnormality occurring in a specific phase is detected for each phase. In this modified example, instead of or in addition to this, a case will be described in which a group including a specific phase in which an abnormality has occurred is detected for each group in units of groups including a plurality of phases.

FIG. 6 is a schematic configuration diagram of an electric motor driving device according to a modification.
For example, each phase of AC motor 2 is divided into a plurality of groups. Accordingly, the single-phase inverters 3-1 to 3-8 are divided into any of a plurality of groups including a first group and a second group so that the number of single-phase inverters in each group is the same. .

For example, the single-phase inverters 3-1 and 3-2 (first single-phase inverter) belong to the first group G1, the single-phase inverters 3-3 and 3-4 (second single-phase inverter) belong to the second group G2, Single-phase inverters 3-5 and 3-6 are classified into a third group G3, and single-phase inverters 3-7 and 3-8 are classified into a fourth group G4. The integration unit 42 integrates the currents IFBK1 and IFBK2 that flow through the first single-phase windings of the single-phase inverters 3-1 and 3-2 included in the first group G1 for each group, and outputs the currents to the second group G2. Currents IFBK3 and IFBK4 that are supplied to the second single-phase windings of single-phase inverters 3-3 and 3-4, respectively, are integrated. The same applies to the third group G3 and the fourth group G4.

For example, the determination unit 43 groups based on the integrated value (integrated value of the first current) based on the currents IFBK1 and IFBK2 and the integrated value (integrated value of the second current) based on the currents IFBK3 and IFBK4. determine the states of a plurality of single-phase inverters included in . The method of the embodiment may be applied to this determination method.

According to this modification, it is possible to detect a group including a specific phase in which an abnormality has occurred. In addition, this modification may be implemented independently and may be added to the example of embodiment.

According to at least one embodiment described above, the drive amount command unit commands the plurality of single-phase inverters to supply current to each of the single-phase windings of the AC motor provided with a plurality of independent single-phase windings. send. The integration unit integrates measured values of a first current flowing through a first single-phase winding of the plurality of single-phase windings at predetermined intervals to generate a first integrated value, A second integrated value is generated by integrating the measured value of the second current flowing through the second single-phase winding in the inside at the predetermined interval. By determining the states of the plurality of single-phase inverters based on the first integrated value and the second integrated value, the determination unit can further increase reliability when driving the AC motor.

At least a part of the above control device may be implemented by a software functional unit that functions by a processor such as a CPU executing a program, or may be implemented entirely by a hardware functional unit such as an LSI. .

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1... Motor drive device, 2... AC motor, 3-1 to 3-8... Single-phase inverter, 4... Motor control part, 2A... Position detector, 31... Main circuit, 32... Current detection part, 33... Current control Part 41... Drive amount command part 42... Integration part 43... Judgment part 44... Control part body

Claims (11)

a drive amount command unit that sends a command to a plurality of single-phase inverters that cause a current to flow through each single-phase winding of an AC motor that is provided with a plurality of single-phase windings that are independent of each other;
Measured values of a first current flowing through a first single-phase winding of the plurality of single-phase windings are integrated at predetermined intervals to generate a first integrated value; an integrator that integrates measured values of the second current flowing through the second single-phase winding at the predetermined intervals to generate a second integrated value;
a determination unit that determines states of the plurality of single-phase inverters based on the first integrated value and the second integrated value;
with
The integration unit
calculating the first integrated value and the second integrated value by fixing the integration period of the first integrated value and the second integrated value, and calculating the moving average of the integrated period;
electric motor drive. The determination unit is
determining that there is an abnormality in the system of the first single-phase winding when the first integrated value is smaller than a predetermined threshold for the second integrated value;
The electric motor drive device according to claim 1. The integration unit
continuing the integration of the first integrated value and the second integrated value over a common predetermined period;
The electric motor driving device according to claim 1 or 2. The integration unit
initializing the first integrated value and the second integrated value in response to a command to stop operation of the AC motor;
The electric motor driving device according to any one of claims 1 to 3. The integration unit
Exclude at least one of an acceleration period and a deceleration period of the rotation speed of the AC motor from the integration period.
The electric motor drive device according to any one of claims 1 to 4 . The determination unit is
Exclude at least one of an acceleration period and a deceleration period of the rotational speed of the AC motor from the period subject to the determination;
The electric motor drive device according to any one of claims 1 to 4 . The integration unit
integrating the first integrated value and the second integrated value over the integration period determined according to the magnitude of the load of the AC motor;
The electric motor drive device according to any one of claims 1 to 4 . The integration unit
Initializing the first integrated value and the second integrated value at timing according to the magnitude of the load of the AC motor;
The electric motor drive device according to claim 4. The plurality of single-phase inverters are divided into any of a plurality of groups including a first group and a second group such that the number of single-phase inverters in each group is the same;
The integration unit
accumulating a first current that each of the plurality of first single-phase inverters included in the first group flows to each first single-phase winding;
accumulating a second current that each of the plurality of second single-phase inverters included in the second group flows to each of the second single-phase windings;
The determination unit is
Based on the integrated value of the first current and the integrated value of the second current, the states of the plurality of single-phase inverters included in the group are determined for each group;
The electric motor drive device according to any one of claims 1 to 4 . 10. The motor drive device according to any one of claims 1 to 9, further comprising a plurality of single-phase inverters that apply current to each of the plurality of single-phase windings that are independent of each other. Sending a command to a plurality of single-phase inverters that apply current to each single-phase winding of an AC motor that has a plurality of single-phase windings that are independent of each other;
Measured values of a first current flowing through a first single-phase winding of the plurality of single-phase windings are integrated at predetermined intervals to generate a first integrated value; Integrating the measured value of the second current flowing through the second single-phase winding at the predetermined interval to generate a second integrated value;
calculating the first integrated value and the second integrated value by fixing the integration period of the first integrated value and the second integrated value, and calculating the moving average of the integrated period as the first integrated value and the second integrated value;
a step of determining states of the plurality of single-phase inverters based on the first integrated value and the second integrated value;
A state detection method for a motor drive device comprising:

Images