Inverter System

Abstract

To provide an inverter system which can suppress a torque ripple caused by a mechanical reason of a multi-phase motor.SOLUTION: The inverter system includes: a plurality of single-phase inverters connected to a plurality of phases of a multi-phase motor to apply an AC voltage to the phases of the multi-phase motor; and a plurality of single-phase controllers for operating the estimated value of a torque ripple caused by a mechanical reason of the multi-phase motor on the basis of the detected value of the mechanical angle of the multi-phase motor and the estimated value of the torque ripple at the time of a reduced-phase operation, and controlling the single-phase inverters on the basis of the correction value corresponding to the estimated value of the torque ripple.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to inverter systems. [Background technology]

[0002] Patent Document 1 discloses an inverter system that can suppress vibrations of a polyphase motor by supplying a balanced AC output to a polyphase load even when a single-phase inverter device of any phase fails and enters reduced-phase operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-25720 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inverter system described in Patent Document 1 does not take into consideration torque ripple due to mechanical factors of the polyphase motor or torque ripple due to magnetic field distribution during reduced-phase operation, making it impossible to suppress vibrations due to mechanical factors of the polyphase motor.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present invention is to provide an inverter system that can suppress torque ripple caused by mechanical factors of a polyphase motor or by reduced-phase operation. [Means for solving the problem]

[0006] The inverter system according to the present disclosure includes a plurality of single-phase inverters connected to a plurality of phases of a polyphase motor, respectively, and applying an AC voltage to each of the plurality of phases of the polyphase motor; and a plurality of single-phase control devices that calculate an estimated value of torque ripple due to mechanical factors of the polyphase motor and torque ripple during reduced-phase operation based on a detected value of the mechanical angle of the polyphase motor, and control each of the plurality of single-phase inverters based on a correction value corresponding to the estimated value of torque ripple. [Effects of the Invention]

[0007] According to the present disclosure, the multiple single-phase control devices calculate torque ripple due to mechanical factors of the multi-phase motor and estimated values ​​of torque ripple during reduced-phase operation based on detected values ​​of the mechanical angle of the multi-phase motor. The multiple single-phase control devices control the multiple single-phase inverters based on correction values ​​corresponding to the estimated torque ripple. This makes it possible to suppress torque ripple due to mechanical factors of the multi-phase motor and reduced-phase operation. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of a power system to which an inverter system according to a first embodiment is applied. [Figure 2] 2 is a block diagram of a main part of a single-phase control device and a main part of an inverter command device of the inverter system according to the first embodiment. FIG. [Figure 3] FIG. 3 is a block diagram of a ripple data table unit of the inverter system according to the first embodiment. [Figure 4] 4 is a flowchart for illustrating the operation of the inverter command device of the inverter system in the first embodiment. [Figure 5] 5 is a flowchart for illustrating the operation of the inverter command device of the inverter system in the first embodiment. [Figure 6] FIG. 10 is a diagram showing the relationship between the mechanical angle and the torque ripple. [Figure 7] FIG. 1 is a diagram showing the relationship between the mechanical angle and the output when a four-phase, four-pole motor is used as a generator in reduced-phase operation. [Figure 8] 1 is a hardware configuration diagram of an inverter command device of an inverter system according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments will be described with reference to the accompanying drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals. Duplicate descriptions of these parts will be appropriately simplified or omitted.

[0010] Embodiment 1 FIG. 1 is a configuration diagram of a power system to which an inverter system according to a first embodiment is applied.

[0011] In FIG. 1, the polyphase motor 1 is a motor having multiple phases. For example, the polyphase motor 1 has four phases. For example, the polyphase motor 1 is a synchronous motor. The type of rotor of the polyphase motor 1 is not important. For example, the rotor of the polyphase motor 1 is a wound rotor. For example, the rotor of the polyphase motor 1 is a permanent magnet rotor.

[0012] The mechanical angle detection device 2 is adjacent to the polyphase electric motor 1. The mechanical angle detection device 2 detects the mechanical angle of the polyphase electric motor 1 and outputs a signal representing the detected value of the mechanical angle.

[0013] The inverter system includes a plurality of single-phase inverters 3, a plurality of current detectors 4, a plurality of single-phase control devices 5, and an inverter command device 6.

[0014] The plurality of single-phase inverters 3 respectively correspond to the plurality of phases of the polyphase motor 1. The plurality of single-phase inverters 3 apply AC voltages to the plurality of phases of the polyphase motor 1, respectively.

[0015] The plurality of current detectors 4 detect the currents flowing through the plurality of phases of the polyphase motor 1, and then output signals representing the detected values ​​of the currents.

[0016] The multiple single-phase control devices 5 respectively correspond to the multiple single-phase inverters 3. Each of the multiple single-phase control devices 5 includes a current command value calculation unit 5a, an induced voltage ripple data unit 5b, a first conversion unit 5c, a d-axis current control unit 5d, a q-axis current control unit 5e, a second conversion unit 5f, and a PWM control unit 5g. Here, the d-axis current refers to a current component in the output current of each single-phase inverter that is orthogonal in phase with the output voltage of each single-phase inverter, and the q-axis current refers to a current component that is in phase with the output voltage of each single-phase inverter.

[0017] The current command value calculation unit 5a receives an input of a current amplitude command value signal from the outside, and calculates a d-axis current command value and a q-axis current command value based on the current amplitude command value.

[0018] The induced voltage ripple data unit 5b receives an input of a signal of the detected value of the mechanical angle from the mechanical angle detection device 2. The induced voltage ripple data unit 5b calculates a d-axis current correction value and a q-axis current correction value based on the detected value of the mechanical angle.

[0019] The first conversion unit 5c receives an input of an electrical angle command value signal from the outside. The first conversion unit 5c receives a signal of a current detection value from the current detector 4. The first conversion unit 5c converts the current detection value into a d-axis actual current detection value and a q-axis actual current detection value based on the electrical angle command value.

[0020] The subtractor 51d outputs a corrected d-axis current command value, which is the difference between the d-axis current command value and the d-axis current correction value.The subtractor 51q outputs a corrected q-axis current command value, which is the difference between the q-axis current command value and the q-axis current correction value.

[0021] The d-axis current control unit 5d receives an input signal of a value obtained by subtracting the d-axis actual current detection value from the corrected d-axis current command value via a subtractor 52d, and calculates a d-axis voltage command value so that the d-axis actual current detection value follows the corrected d-axis current command value.

[0022] The q-axis current control unit 5e receives an input of a signal obtained by subtracting the q-axis actual current detection value from the corrected q-axis current command value via the subtractor 52q, and calculates a q-axis voltage command value so that the q-axis actual current detection value follows the corrected q-axis current command value.

[0023] The second conversion unit 5f receives an input of a d-axis voltage command value signal from the d-axis current control unit 5d. The second conversion unit 5f receives an input of a q-axis voltage command value signal from the q-axis current control unit 5e. The second conversion unit 5f receives electrical angle command values ​​corresponding to each single-phase inverter from the electrical angle calculation unit 6d. The second conversion unit 5f calculates a voltage amplitude command value based on the d-axis voltage command value, the q-axis voltage command value, and the electrical angle command value.

[0024] The PWM control unit 5g receives an input of a voltage amplitude command value signal from the second conversion unit 5f, and controls the single-phase inverter 3 by PWM control at a predetermined carrier frequency based on the voltage amplitude command value.

[0025] The inverter command device 6 includes a first angular velocity calculation unit 6a, a PI control unit 6b, an inverter operation signal generation unit 6c, and an electrical angle calculation unit 6d.

[0026] The first angular velocity calculation unit 6a receives an input of a signal representing the detected value of the mechanical angle from the mechanical angle detection device 2. The first angular velocity calculation unit 6a calculates a detected value of the angular velocity of the polyphase electric motor 1 by differentiating the detected value of the mechanical angle with respect to time.

[0027] The PI control unit 6b receives an input of a speed command value signal from the outside. The PI control unit 6b receives an input of a signal of the detected value of the angular velocity from the first angular velocity calculation unit 6a. The PI control unit 6b calculates a current amplitude command value based on a value obtained by subtracting the detected value of the angular velocity from the speed command value so that the detected value of the angular velocity follows the speed command value. The PI control unit 6b outputs the current amplitude command value to the multiple single-phase control devices 5.

[0028] The inverter operation signal generating unit 6c determines which single-phase inverters 3 to operate when it receives abnormality detection signals for the multiple single-phase inverters 3 from an abnormality detection unit (not shown) and operation signals from a higher-level device (not shown). The inverter operation signal generating unit 6c outputs DEB / GB command signals to the multiple single-phase control devices 5 based on the abnormality signals for the multiple single-phase inverters 3 and the operation signals from the higher-level device. Note that the DEB / GB signals are not shown in FIG. 1. Each single-phase control device 5 deblocks or gate-blocks each single-phase inverter 3 based on the received DEB / GB command signal. The inverter operation signal generating unit 6c outputs multiple operable inverter signals to the electrical angle calculation unit based on the abnormality signals for the multiple single-phase inverters 3. The operable inverter signals are signals that indicate which single-phase inverters 3 are operable among the multiple single-phase inverters 3.

[0029] The electrical angle calculation unit 6d receives an input of a signal representing the detected mechanical angle value from the mechanical angle detection device 2. The electrical angle calculation unit 6d receives an input of a plurality of operable inverter signals (e.g., operable inverter signals 1 to 4) for each single-phase inverter 3 from the inverter operation signal generation unit 6c. Hereinafter, in this specification, the plurality of operable inverter signals for each single-phase inverter 3 will be collectively referred to as the "plurality of operable inverter signals." The electrical angle calculation unit 6d outputs electrical angle command value signals to the plurality of single-phase control devices 5 based on the detected mechanical angle value and the plurality of operable inverter signals.

[0030] Next, the main parts of the single-phase control device 5 and the main parts of the inverter command device 6 will be described with reference to FIG.

[0031] FIG. 2 is a block diagram of a main part of the single-phase control device and a main part of the inverter command device of the inverter system according to the first embodiment.

[0032] As shown in FIG. 2, the induced voltage ripple data unit 5b includes a ripple data table unit 7, a d-axis gain unit 8, and a q-axis gain unit 9.

[0033] The ripple data table unit 7 receives input of a plurality of operable inverter signals from the inverter operation signal generation unit 6c. The ripple data table unit 7 receives input of a signal of a detected mechanical angle value from the mechanical angle detection device 2. The ripple data table unit 7 calculates the d-axis component and the q-axis component of an estimated value of the torque ripple of the polyphase motor 1 based on the plurality of operable inverter signals and the detected mechanical angle value.

[0034] The d-axis gain unit 8 receives an input of a signal of the d-axis component of the torque ripple estimate value from the ripple data table unit 7. The d-axis gain unit 8 calculates a d-axis current correction value based on the d-axis component of the torque ripple estimate value. The d-axis gain unit 8 outputs a signal of the d-axis current correction value.

[0035] The q-axis gain unit 9 receives an input of a signal of the q-axis component of the torque ripple estimated value from the ripple data table unit 7. The q-axis gain unit 9 calculates a q-axis current correction value based on the q-axis component of the torque ripple estimated value. The q-axis gain unit 9 outputs a signal of the q-axis current correction value.

[0036] As shown in FIG. 2, the electrical angle calculation unit 6d includes an electrical angle conversion unit 10, an operating vehicle number determination unit 11, a current phase interval calculation unit 12, and an electrical angle phase allocation unit 13.

[0037] The electrical angle converter 10 receives an external input of a signal representing the detected value of the mechanical angle. The electrical angle converter 10 converts the detected value of the mechanical angle θm into a detected value of the electrical angle θe by multiplying the input signal representing the detected value of the mechanical angle θm by the number of poles p of the polyphase motor 1 and dividing the result by 2, as shown in the following equation (1).

[0038] θe=θm×p / 2 (1)

[0039] The operating unit number determination unit 11 receives input of a plurality of operable inverter signals from the outside, and determines the operable single-phase inverters 3 based on the plurality of operable inverter signals.

[0040] The current phase interval calculation unit 12 receives an input of a signal of the operable single-phase inverters 3 from the operating unit number determination unit 11. The current phase interval calculation unit 12 calculates 360° / the number of operable single-phase inverters 3, thereby calculating the interval of the current phases of the operable single-phase inverters 3.

[0041] The electrical angle phase allocation unit 13 receives an input of a signal representing the detected value of the electrical angle from the electrical angle conversion unit 10. The electrical angle phase allocation unit 13 receives an input of a signal representing the operable single-phase inverters 3 from the operating unit number determination unit 11. The electrical angle phase allocation unit 13 receives an input of a signal representing the interval between the current phases of the operable single-phase inverters 3 from the current phase interval calculation unit 12. The electrical angle phase allocation unit 13 outputs signals representing the respective electrical angle command values ​​(electrical angle command values ​​1 to 4) to each of the operable single-phase inverters 3 based on the detected value of the electrical angle and the interval between the current phases of the operable single-phase inverters 3.

[0042] Next, the ripple data table unit 7 will be described with reference to FIG.

[0043] FIG. 3 is a block diagram of a ripple data table unit of the inverter system according to the first embodiment.

[0044] As shown in FIG. 3, the apparatus includes a second angular velocity calculation unit 14, a first ripple data unit 15, a second ripple data unit 16, and a synthesis unit 17.

[0045] The second angular velocity calculation unit 14 receives an input of a signal representing the detected value of the mechanical angle from the outside. The second angular velocity calculation unit 14 calculates the detected value of the angular velocity by differentiating the detected value of the mechanical angle with respect to time.

[0046] The first ripple data unit 15 stores information about a first reference value of torque ripple due to mechanical factors of the polyphase motor 1. The first reference value of torque ripple is calculated from induced voltages of multiple phases of the polyphase motor 1 when the polyphase motor 1 is mechanically rotated at a constant rotational speed by an external power source during a test at a factory, etc. The first reference value of torque ripple is data for a mechanical angle of 2π.

[0047] The first reference value for torque ripple can be determined, for example, by connecting a resistive load to each AC input terminal of the multi-phase motor 1 so that the voltage or output power can be measured, and then rotating the motor mechanically at a constant rotational speed using an external power source, i.e., operating it as a generator, and measuring the induced voltage or output power for one mechanical rotation. The difference from the reference induced voltage or reference output power can then be determined. That is, the deviation from the sine wave for each phase's mechanical angle can be converted to the d-axis and q-axis, and obtained as a torque ripple function for the mechanical angle, as shown in Figure 6. Generally, this torque ripple is of a higher order than the frequency of the mechanical angle. It is desirable to maintain a constant angular velocity during one rotation when the motor is rotated mechanically.

[0048] The first ripple data unit 15 receives an input of a signal representing the detected value of the mechanical angle from the outside. The first ripple data unit 15 receives an input of a signal representing the detected value of the angular velocity from the second angular velocity calculation unit 14. The first ripple data unit 15 calculates a first estimated value of the torque ripple due to mechanical factors of the polyphase electric motor 1 based on the detected value of the mechanical angle and the detected value of the angular velocity. In this case, the first ripple data unit 15 calculates the first estimated value of the torque ripple due to mechanical factors of the polyphase electric motor 1 based on a first reference value of the torque ripple.

[0049] The second ripple data unit 16 stores information about a second reference value of torque ripple that occurs when the current in the coil connected to the failed single-phase inverter 3 becomes zero. The second reference value of torque ripple is calculated in advance based on the magnetic pole arrangement of the coil corresponding to the failed inverter. Since calculating the torque ripple during reduced-phase operation due to the magnetic pole arrangement of the coil is complicated, the second reference value of torque ripple may alternatively be determined by factory testing or the like. The second reference value of torque ripple is data for a mechanical angle of 2π. Note that the data for a mechanical angle of 2π may be created by repeating data for an electrical angle of 2π by a value obtained by dividing the number of poles by 2. In other words, if the number of poles is p, the data for a mechanical angle of 2π may be obtained by repeating the electrical angle of 2π p / 2 times.

[0050] The second ripple data unit 16 receives an external input of a signal representing the detected mechanical angle. The second ripple data unit 16 receives an external input of a plurality of operable inverter signals. The second ripple data unit 16 receives an external input of a signal representing a q-axis current command value. The second ripple data unit 16 calculates a second estimated value of torque ripple caused by the current in the coil connected to the failed single-phase inverter 3 becoming zero, based on the detected mechanical angle, the plurality of operable inverter signals, and the q-axis current command value. In this case, the second ripple data unit 16 calculates the second estimated value of torque ripple caused by the current in the coil connected to the failed single-phase inverter 3 becoming zero, based on a second reference value of the torque ripple.

[0051] The second reference value of the torque ripple may be measured in advance by intentionally disabling the single-phase inverter 2 during a factory test or the like. Alternatively, the second reference value of the torque ripple may be measured by, for example, connecting a resistive load to each AC input terminal of a phase other than the one assumed to be the faulty phase of the polyphase motor 1 so that the voltage or current can be measured, and furthermore, the AC input terminal of the phase assumed to be the faulty phase is mechanically rotated at a constant rotational speed by an external power source (operated as a generator), and the output power of each phase for one mechanical rotation is measured. Figure 7 is a schematic diagram showing the total output power of each phase in the above case.

[0052] Figure 7 shows an example where the polyphase motor 1 is a four-phase, four-pole motor. The vertical axis is torque, which corresponds to the power output when used as a generator. The dashed line a represents the torque when the single-phase inverter 3 is functioning properly, and the solid line b represents the torque when the first phase of the single-phase inverter fails. The horizontal axis represents the angle, with both the mechanical angle and the electrical angle shown. As a four-pole motor is assumed, the mechanical angle of 2π becomes the electrical angle of 4π.

[0053] The difference between the output power when all phases are healthy and the output power when a specific phase is missing (terminal open) corresponds to the torque ripple. Therefore, the difference between dashed line a and solid line b is the power ripple equivalent to the torque ripple. The second torque ripple criterion is obtained by operating the polyphase motor 1 as a generator with a resistor as the load, and from the difference between the actual measured value when resistors are connected to all terminals and the actual measured value of the output power when resistors are connected to the phase assumed to have a fault, the power equivalent to the torque ripple can be obtained as a function of angle (electrical angle or mechanical angle). The second torque ripple criterion is generated to compensate for this ripple component.

[0054] In the case of four poles, an electrical angle of 4π corresponds to a mechanical angle of 2π. However, since the values ​​for mechanical angles 0 to π and mechanical angles π to 2π are theoretically equal, the second reference data for torque ripple may be data for electrical angles 0 to 2π, and data for mechanical angles π to 2π may be automatically generated. That is, in the case of a polyphase motor 1 with n phases and p poles, data for mechanical angles 0 to 4π / p (i.e., electrical angles 0 to 2π) may be created, and data for mechanical angles 4π / p to 2π may be obtained by repeating the data for mechanical angles 0 to 4π / p (i.e., electrical angles 0 to 2π) m times. Here, the number of repetitions m is given by the following equation (2):

[0055] m=p / 2-1 (2)

[0056] Furthermore, in the case where one of the single-phase inverters 3 of the kth phase in the entire n-phase polyphase motor 1 fails, the torque ripple is, in principle, the same as the torque ripple when one of the single-phase inverters 3 of the 1st phase fails, but is delayed by the electrical angle phase α calculated by the following equation (3).

[0057] α=(k-1)×2π / n (3)

[0058] Therefore, when a failure of only one of the single-phase inverters 3 is assumed, the second torque ripple reference data may be generated assuming a failure of only the first phase, and when a failure occurs in another phase, the second torque ripple reference data may be used with a delay of the electrical angle phase α.

[0059] When failures of multiple single-phase inverters 3 are assumed, the torque ripple data of only one phase described above may be used to calculate torque ripple data showing the relationship between phase and torque assuming a single-phase failure of only each of the failed phases, and the data may be added together using the principle of superposition to be used as the second torque ripple reference data.

[0060] Note that due to differences in motor structure, etc., when assuming a failure of multiple phases, the overlap principle may not necessarily provide the required torque ripple accuracy due to the influence of magnetic field distribution. For example, consider the case of a failure of two single-phase inverters 3. In this case, only one type of torque ripple data with the same phase difference between the first and second failed phases can be acquired and delayed or advanced according to the phase of the failed phase to generate second torque ripple reference data. That is, for example, torque ripple data assuming a failure of the first and n1 phases of the single-phase inverter 3 can also be used when a failure of the n2 and n2+n1 phases is assumed. In other words, by delaying the data by the phase difference between the first and n2 phases, second reference data for a failure of the n2 and n2+n1-1 phases can be generated and used. Here, n1 and n2 are integers.

[0061] In other words, it is not necessary to prepare data for all combinations of torque ripple data for faulty single-phase inverters 3 during reduced-phase operation. If a failure of only one phase of the single-phase inverter 3 is assumed, only one type of data is prepared. If a failure of multiple phases of the single-phase inverter 3 is assumed, only the number of types of phase differences between the faulty phases is prepared, and the phase of the torque ripple data can be advanced or delayed as necessary depending on the faulty phase.

[0062] When obtaining data for creating the first reference value of torque ripple and the second reference value of torque ripple through testing, it is not necessary to carry out the test for each individual polyphase motor 1, but rather it is possible to carry out the test for one motor of the same model and reuse the test for motors of the same model. The reason for this is that torque ripple depends on the structure of the motor, and therefore torque ripple is approximately the same for motors of the same model.

[0063] In the torque ripple suppression mode, the synthesizer 17 receives an input of a signal representing a first torque ripple estimate from the first ripple data unit 15. In the phase reduction mode, the synthesizer 17 receives an input of a signal representing a second torque ripple estimate from the second ripple data unit 16. The synthesizer 17 calculates the d-axis and q-axis components of the torque ripple estimate based on the first and second torque ripple estimates. The command for the torque ripple suppression mode is set by a command signal from a higher-level unit (not shown) or a predetermined speed command value, and is transmitted from the inverter command device 6 to the synthesizer 17 in the single-phase control device 5. The command for the phase reduction mode is transmitted from the operating unit number determination unit 11 of the inverter command device 6 to the synthesizer 17 in the single-phase control device 5 when a fault occurs in any of the multiple single-phase inverters.

[0064] Next, the operation of the inverter command device 6 will be described with reference to FIGS.

[0065] 4 and 5 are flowcharts for explaining the operation of the inverter command device of the inverter system according to the first embodiment.

[0066] In step S1, the inverter command device 6 determines whether or not an operation command signal has been input from the outside.

[0067] If an operation command signal is not input from the outside in step S1, the inverter command device 6 performs the operation of step S2. In step S2, the inverter command device 6 stops the operation of all single-phase inverters 3.

[0068] If an external operation command signal is input in step S1, the inverter command device 6 performs the operation in step S3. In step S3, the inverter command device 6 determines whether or not any single-phase inverter 3 is faulty.

[0069] If there is no faulty single-phase inverter 3 in step S3, the inverter command device 6 performs the operation of step S4. In step S4, the inverter command device 6 determines whether or not it is necessary to suppress the torque ripple.

[0070] If it is determined in step S4 that torque ripple suppression is necessary, the inverter command device 6 performs the operation of step S5. In step S5, the inverter command device 6 outputs a torque ripple suppression mode command, and then the process proceeds to step S6.

[0071] In step S6, the induced voltage ripple data unit 5b of the single-phase control device 5 receives the torque ripple suppression mode command, calculates a first torque ripple estimate, and generates a d-axis current correction value and a q-axis current correction value based on the calculated value. All single-phase inverters 3 are operated so that the d-axis actual current detection value follows the corrected d-axis current command value based on their respective d-axis current command values ​​and d-axis current correction values. Also, all single-phase inverters 3 are operated so that the q-axis actual current detection value follows the corrected q-axis current command value based on their respective q-axis current command values ​​and q-axis current correction values.

[0072] If torque ripple suppression is not required in step S4, the inverter command device 6 performs the operation of step S7. In step S7, the inverter command device 6 operates all the single-phase inverters 3 in a mode other than the torque ripple suppression mode.

[0073] If there is a faulty single-phase inverter 3 in step S3, the inverter command device 6 performs the operation of step S8. In step S8, the inverter command device 6 determines whether the number of faulty single-phase inverters 3 is less than the allowable number. Even if the number is within the allowable number, the inverter command device 6 determines whether the phases of the faulty single-phase inverters 3 are close to each other and whether the torque ripple during the expected reduced phase operation is within the allowable value.

[0074] If the number of faulty single-phase inverters 3 is less than the allowable number in step S8, and if the torque ripple during the expected reduced-phase operation is within the allowable value, the inverter command device 6 performs the operation of step S9. In step S9, the inverter command device 6 outputs a command for the reduced-phase operation mode.

[0075] Thereafter, the inverter command device 6 performs the operation of step S10. In step S10, the inverter command device 6 calculates the phase of the electrical angle command value. Thereafter, the inverter command device 6 performs the operation of step S11. In step S11, the inverter command device 6 determines whether or not it is necessary to suppress torque ripple.

[0076] If it is determined in step S11 that torque ripple suppression is necessary, the inverter command device 6 performs the operation of step S12. In step S12, the inverter command device 6 outputs a torque ripple suppression mode command, and then the process proceeds to step S13.

[0077] In step S13, the induced voltage ripple data unit 5b of each non-faulty single-phase control device 5 calculates a first torque ripple estimate in response to a torque ripple suppression mode command, calculates a second torque ripple estimate that reflects the presence of a faulty single-phase inverter 3 in response to a phase reduction operation mode command, combines the first and second torque ripple estimates, and generates a d-axis current correction value and a q-axis current correction value based on the combined torque ripple estimate. Each non-faulty single-phase inverter 3 is operated so that the d-axis actual current detection value follows the corrected d-axis current command value based on its respective d-axis current command value and d-axis current correction value. Furthermore, all single-phase inverters 3 are operated so that the q-axis actual current detection value follows the corrected q-axis current command value based on its respective q-axis current command value and q-axis current correction value.

[0078] If torque ripple suppression is not required in step S11, in step S13, the induced voltage ripple data unit 5b of each non-faulty single-phase control device 5 receives the command for the reduced-phase operation mode, calculates a second torque ripple estimate that reflects the presence of the faulty single-phase inverter 3, and generates a d-axis current correction value and a q-axis current correction value based on the calculated value. Each non-faulty single-phase inverter 3 is operated so that the d-axis actual current detection value follows the corrected d-axis current command value based on its respective d-axis current command value and d-axis current correction value. Furthermore, all single-phase inverters 3 are operated so that the q-axis actual current detection value follows the corrected q-axis current command value based on its respective q-axis current command value and q-axis current correction value.

[0079] If the number of faulty single-phase inverters 3 is not less than the allowable number in step S8, or if the torque ripple during the expected reduced-phase operation is greater than the allowable value, the inverter command device 6 performs the operation of step S15. In step S15, the inverter command device 6 stops the operation of all single-phase inverters 3. Furthermore, an alarm may be output to a higher-level device or an operator (not shown).

[0080] According to the first embodiment described above, the multiple single-phase control devices 5 calculate an estimated value of torque ripple due to mechanical factors of the multi-phase motor 1 based on a detected value of the mechanical angle of the multi-phase motor 1. The multiple single-phase control devices 5 control the multiple single-phase inverters 3 based on a correction value corresponding to the estimated value of torque ripple. Therefore, the torque ripple due to mechanical factors of the multi-phase motor 1 can be suppressed.

[0081] Furthermore, the plurality of single-phase control devices 5 calculate an estimated value of torque ripple due to mechanical factors of the polyphase motor 1 in accordance with the angular velocity of the polyphase motor 1. This makes it possible to more reliably suppress torque ripple due to mechanical factors of the polyphase motor 1.

[0082] Furthermore, if any of the plurality of single-phase inverters 3 fails, the inverter command device 6 outputs a signal of an electrical angle command value for the remaining non-failed single-phase inverters 3. At this time, the single-phase control devices 5 corresponding to the remaining non-failed single-phase inverters 3 respectively calculate an estimated value of torque ripple that will be generated due to a failure of any of the plurality of single-phase inverters 3, in accordance with the arrangement of the coils of the plurality of phases corresponding to the remaining non-failed single-phase inverters 3. This makes it possible to suppress torque ripple caused by reduced-phase operation of the polyphase motor 1.

[0083] Furthermore, the corresponding single-phase control device 5 calculates an estimated value of torque ripple that occurs when any of the single-phase inverters 3 fails, depending on the d-axis current command value. This makes it possible to more reliably suppress torque ripple caused by reduced-phase operation of the multi-phase motor 1.

[0084] The inverter system of the first embodiment may be applied to a polyphase motor 1 having four or more phases. In this case, the polyphase motor 1 may be controlled using the same number of single-phase inverters 3 and single-phase control devices 5 as the number of phases of the polyphase motor 1.

[0085] Next, an example of the inverter command device 6 will be described with reference to FIG.

[0086] FIG. 8 is a hardware configuration diagram of the inverter command device of the inverter system according to the first embodiment.

[0087] Each function of the inverter command device 6 can be realized by a processing circuit. For example, the processing circuit includes at least one processor 100a and at least one memory 100b. For example, the processing circuit includes at least one dedicated hardware 200.

[0088] When the processing circuit includes at least one processor 100a and at least one memory 100b, the functions of the inverter command device 6 are realized by software, firmware, or a combination of software and firmware. At least one of the software and firmware is written as a program. At least one of the software and firmware is stored in the at least one memory 100b. The at least one processor 100a realizes the functions of the inverter command device 6 by reading and executing the program stored in the at least one memory 100b. The at least one processor 100a is also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. For example, the at least one memory 100b may be a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM, a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD.

[0089] When the processing circuit includes at least one dedicated hardware 200, the processing circuit is realized, for example, by a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. For example, each function of the inverter command device 6 is realized by a processing circuit. For example, each function of the inverter command device 6 is realized collectively by a processing circuit.

[0090] Some of the functions of the inverter command device 6 may be realized by dedicated hardware 200, and the other parts may be realized by software or firmware. For example, the function of the inverter operation signal generating unit 6c may be realized by a processing circuit as dedicated hardware 200, and the functions other than the function of the inverter operation signal generating unit 6c may be realized by at least one processor 100a reading and executing a program stored in at least one memory 100b.

[0091] In this way, the processing circuitry realizes the functions of the inverter command device 6 by using hardware 200, software, firmware, or a combination of these.

[0092] Although not shown, each function of the single-phase control device 5 is also realized by a processing circuit equivalent to the processing circuit that realizes each function of the inverter command device 6.

[0093] According to the present disclosure, it is possible to provide an inverter system that can suppress torque ripple caused by mechanical factors of a polyphase motor or by reduced-phase operation. [Explanation of symbols]

[0094] REFERENCE SIGNS LIST 1 Multi-phase motor, 2 Mechanical angle detection device, 3 Single-phase inverter, 4 Current detector, 5 Single-phase control device, 5a Current command value calculation unit, 5b Induced voltage ripple data unit, 5c First conversion unit, 5d D-axis current control unit, 5e Q-axis current control unit, 5f Second conversion unit, 5g PWM control unit, 6 Inverter command device, 6a First angular velocity calculation unit, 6b PI control unit, 6c Inverter operation signal generation unit, 6d Electrical angle calculation unit, 7 Ripple data table unit, 8 D-axis gain unit, 9 Q-axis gain unit, 10 Electrical angle conversion unit, 11 Unit for determining the number of operating units, 12 Current phase interval calculation unit, 13 Electrical angle phase allocation unit, 14 Second angular velocity calculation unit, 15 First ripple data unit, 16 Second ripple data unit, 17 Synthesis unit, 100a processor, 100b memory, 200 hardware

Claims

1. a plurality of single-phase inverters connected to a plurality of phases of a polyphase motor, respectively, and applying an AC voltage to each of the plurality of phases of the polyphase motor; a plurality of single-phase control devices that calculates estimated values ​​of torque ripple due to mechanical factors of the polyphase motor and torque ripple during reduced-phase operation based on detected values ​​of mechanical angles of the polyphase motor, and controls the plurality of single-phase inverters based on correction values ​​corresponding to the estimated torque ripple; An inverter system equipped with

2. 2. The inverter system according to claim 1, wherein the plurality of single-phase control devices each calculate an estimated value of torque ripple due to mechanical factors of the polyphase motor in accordance with the angular velocity of the polyphase motor.

3. an inverter command device that outputs, when any one of the plurality of single-phase inverters fails, a signal of an electrical angle command value for the remaining single-phase inverter that is not faulty; Equipped with 3. The inverter system according to claim 1, wherein a plurality of single-phase control devices respectively corresponding to the remaining non-faulty single-phase inverters calculate estimated values ​​of torque ripples caused by a failure in any of the plurality of single-phase inverters in accordance with arrangements of coils of a plurality of phases of the polyphase motor respectively corresponding to the remaining non-faulty single-phase inverters.

4. 4. The inverter system according to claim 3, wherein a plurality of single-phase control devices respectively corresponding to the remaining non-faulty single-phase inverters calculate, in accordance with a d-axis current command value, an estimated value of torque ripple that will be generated when any of the plurality of single-phase inverters has failed.

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