JP6921273B1 - Rotating machine control device - Google Patents

Abstract

When a plurality of PWM-controlled inverters are operated in parallel, if the carrier frequency region is limited for each inverter by paying attention to the reduction of noise, the switching loss of an electric motor using a higher carrier frequency always deteriorates. However, there is a problem that the current ripple always deteriorates in the motor using a low carrier frequency. SOLUTION: The relationship between an input / output state of an inverter and a carrier frequency is set as one PWM pattern, and the inverter has a combination pattern in which two or more of the PWM patterns are combined according to a region of the input / output state. It is provided with a PWM pattern determination unit that switches the PWM pattern according to the combination pattern that is different for each. [Selection diagram] Fig. 1

Description

The present application relates to a rotary machine control device.

When a plurality of inverters are operated in parallel, the PWM pattern, which is the relationship between the input / output state of the inverters and the carrier frequency, is generally common to the plurality of inverters. However, when the carrier frequencies operating in a plurality of inverters match, the noise generated by the switching of the inverter elements overlaps, and there is a problem that the noise becomes large.

As a countermeasure against the above problem, for example, a technique such as the following Patent Document 1 is known. Patent Document 1 shows that noise generated by switching of inverter elements is reduced by setting carrier frequencies having a specific frequency width so as not to overlap each other among a plurality of inverters.

International Publication No. 2011/135687

If the carrier frequency is high, the switching loss due to PWM control increases, and if the carrier frequency is low, the current ripple deteriorates and the control becomes unstable, which is a problem of the rotary machine control device by PWM control. In order to perform stable PWM control, it is necessary to consider switching loss and current ripple when setting the PWM pattern, and make appropriate settings so that switching loss and current ripple do not increase according to the fundamental frequency or output current of the inverter. There is a need to.

However, in the rotary machine control device described in Patent Document 1, only the reduction of noise is focused on, the switching loss always deteriorates in the motor using a higher carrier frequency, and the current in the motor using a lower carrier frequency. There was a problem that the ripple always got worse.

In view of these problems, the present application can reduce noise while performing stable PWM control in consideration of reduction of switching loss and reduction of current ripple when operating a plurality of inverters in parallel. The purpose is to obtain a rotating machine control device.

The rotary machine control device according to the present application is a rotary machine control device having a plurality of inverters that are PWM-controlled, and the relationship between the input / output state of the inverter and the carrier frequency is set as one PWM pattern, and the input / output state of the input / output state. It has a combination pattern in which two or more of the PWM patterns are combined according to a region, and is provided with a PWM pattern determination unit that switches the PWM pattern according to the combination pattern that is different for each inverter.

According to the rotary machine control device of the present application, two or more PWM patterns can be set for each inverter, so that stable PWM control can be performed by switching to an appropriate PWM pattern according to the region of the input / output state. Further, since the combination pattern in which the PWM pattern is combined is different for each inverter, it is possible to reduce noise due to the overlap of carrier frequencies between the inverters.

It is a block diagram which shows the rotary machine control device which concerns on Embodiment 1. FIG. It is a figure explaining the processing circuit of the inverter control part which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern by the fundamental wave frequency of the inverter which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern by the output current of the inverter which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern by the fundamental wave frequency of the inverter which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern using the random PWM of the inverter which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern between a plurality of inverters which concerns on Embodiment 1. FIG. It is a flowchart which shows the operation by the PWM pattern of the inverter which concerns on Embodiment 1. It is a flowchart which shows the operation by the PWM pattern of the inverter which concerns on Embodiment 1. It is a figure which shows the setting example of the PWM pattern between a plurality of inverters which concerns on Embodiment 1. FIG. It is a flowchart which shows the operation by the PWM pattern of the inverter which concerns on Embodiment 1. It is a figure which shows the setting example of the PWM pattern by the fundamental wave frequency of the inverter which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern between a plurality of inverters which concerns on Embodiment 1. FIG. It is a figure which shows the setting example of the PWM pattern between a plurality of inverters which concerns on Embodiment 1. FIG.

Embodiment 1.
The inverter and the rotating machine according to the first embodiment will be described with reference to the drawings. FIG. 1 is a configuration diagram of a rotary machine control device including a plurality of inverters according to the present embodiment and a plurality of rotary machines driven by the rotary machine control device. In the following description of the embodiment, the case where the inverter and the rotating machine driven by the inverter are two units each will be described.

For example, the first rotating machine 1a is a permanent magnet type synchronous rotating machine having a plurality of phases (three phases in this example) windings on the stator and a permanent magnet on the rotor, and the second rotating machine. Reference numeral 1b is a permanent magnet type synchronous rotor having a stator having a plurality of phases (three phases in this example) windings and a rotor having a permanent magnet.

The rotary machine control device 100 includes a first inverter 20a and a first inverter control unit 30a for controlling the first inverter 20a for driving the first rotary machine 1a. Further, the rotary machine control device 100 has a second inverter 20b for driving the second rotary machine 1b, and a second inverter control unit 30b for controlling the second inverter 20b.

The first inverter 20a is a power conversion device that converts DC power of a DC power supply into AC power and supplies it to the windings of a plurality of phases of the first rotating machine 1a, and has a plurality of switching elements. .. The second inverter 20b is a power conversion device that converts the DC power of the DC power supply into AC power and supplies it to the multi-phase windings of the second rotating machine 1b, and has a plurality of switching elements. .. Each of the first and second inverters 20a and 20b corresponds to the winding of each phase, the switching element on the positive electrode side connected to the positive electrode side of the DC power supply, and the negative electrode connected to the negative electrode side of the DC power supply. A series circuit in which the switching element on the side is connected in series is provided. The connection points of the two switching elements in each series circuit are connected to the windings of the corresponding phases of the first and second rotating machines 1a and 1b. Each of the first and second inverters 20a and 20b has a current sensor that detects the output current flowing through each winding. The detected output current is input to the first and second inverter control units 30a and 30b as effective values of the three-phase alternating current, respectively.

As the switching element, an IGBT (Insulated Gate Bipolar Transistor) in which diodes are connected in antiparallel, a bipolar transistor in which diodes are connected in antiparallel, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or the like is used. The gate terminal of each switching element is connected to the first and second PWM control units 31a and 31b provided in the first and second inverter control units 30a and 30b, respectively, via a gate drive circuit or the like. There is. In this way, each switching element is turned on or off by the first and second PWM control units 31a and 31b provided in the first and second inverter control units 30a and 30b, respectively.

The first inverter control unit 30a has a first PWM control unit 31a and a first PWM pattern determination unit 32a. The first PWM control unit 31a is an AC voltage developed into a three-phase AC in which the phase of the sine wave of the fundamental wave frequency is shifted by 120 degrees according to the fundamental wave frequency given to the first inverter control unit 30a as a command value. Generate a pattern. The AC voltage pattern of each phase of these AC voltages is compared with the carrier wave (for example, triangular wave) generated by the carrier frequency instructed by the PWM pattern determination unit, and a switching signal is generated based on the comparison result. The carrier frequency of the first PWM control unit 31a is determined by the first PWM pattern determination unit 32a based on the input / output state 33a input as sensing information to the first inverter control unit 30a. Details will be described later.

The second inverter control unit 30b has a second PWM control unit 31b and a second PWM pattern determination unit 32b. The second PWM control unit 31b is an AC voltage developed into a three-phase AC in which the phase of the sine wave of the fundamental wave frequency is shifted by 120 degrees according to the fundamental wave frequency given to the second inverter control unit 30b as a command value. Generate a pattern. The AC voltage pattern of each phase of these AC voltages is compared with the carrier wave (for example, triangular wave) generated by the carrier frequency instructed by the PWM pattern determination unit, and a switching signal is generated based on the comparison result. The carrier frequency of the second PWM control unit 31b is determined by the second PWM pattern determination unit 32b based on the input / output state 33b input as sensing information to the second inverter control unit 30b. Details will be described later.

As shown in FIG. 2, the first inverter control unit 30a and the second inverter control unit 30b include a processing circuit centered on the processor 201 and the storage device 202, and the processing of each unit is realized by the processing circuit. .. As the processing circuit, an ASIC (Application Specific integrated circuit), an FPGA (Field Programmable Gate Array), various logic circuits, various signal processing circuits, and the like may be provided.

The first inverter control unit 30a collects information in the input / output state 33a from various devices and sensors including the first inverter 20a and the first rotating machine 1a. For example, the fundamental wave frequency 33a1 which is a command value given to the first inverter control unit 30a, and the output current 33a2 of the first inverter 20a. The fundamental wave frequency 33a1 is a command value proportional to the rotation speed of the first rotating machine 1a, and the rotation speed sensed from the first rotating machine 1a may be substituted. Further, the output current 33a2 is input to the first inverter control unit 30a as an effective value of the output current of each phase of the first inverter 20a described above. This current value may substitute the current value of the DC power supply supplied to the first inverter 20a. Further, the output current 33a2 may be a torque component current or a current amplitude.

The second inverter control unit 30b collects information in the input / output state 33b from various devices and sensors including the second inverter 20b and the second rotating machine 1b. For example, the fundamental wave frequency 33b1 which is a command value given to the second inverter control unit 30b, and the output current 33b2 of the second inverter 20b. The fundamental wave frequency 33b1 is a command value proportional to the rotation speed of the second rotating machine 1b, and the rotation speed sensed from the second rotating machine 1b may be substituted. Further, the output current 33b2 is input to the second inverter control unit 30b as an effective value of the output current of each phase of the second inverter 20b described above. This current value may substitute the current value of the DC power supply supplied to the second inverter 20b. Further, the output current 33b2 may be a torque component current or a current amplitude.

Hereinafter, in FIGS. 3 to 6, the first PWM pattern determination unit 32a corresponding to the first inverter 20a and the second PWM pattern determination unit 32b corresponding to the second inverter 20b are provided, respectively. The PWM pattern will be described. Since there is no difference in the operation and function of the first and second PWM pattern determination units 32a and 32b for the input / output states 33a and 33b in either of the first and second PWM patterns, the following description will be made. Unless otherwise specified, the first PWM pattern determination unit 32a and its input / output state 33a will be described as an example.

FIG. 3 shows an example in which two PWM patterns are set and the PWM patterns are switched according to the fundamental wave frequency 33a1 of the first inverter 20a. At this time, there are two PWM patterns, asynchronous PWM and synchronous PWM. When the fundamental wave frequency 33a1 is low, the carrier frequency is kept constant, and when the carrier frequency becomes the threshold value a or more, the carrier frequency is increased in proportion to the increase of the fundamental wave frequency 33a1.

There are some constraints in determining the PWM pattern. First, when the carrier frequency is set high, the carrier cycle becomes very fine, so that PWM control can be performed in a state closer to a continuous waveform, and the stability of control is improved. On the other hand, there is a concern that the number of times the element is switched by PWM control increases and the switching loss increases. On the contrary, if the carrier frequency is set low, the switching loss is reduced, but there is a concern that the control becomes unstable. As described above, there is a trade-off relationship between switching loss and control stability in setting the carrier frequency, and it is necessary to set it appropriately.

As the fundamental wave frequency 33a1 of the first inverter 20a becomes higher, it is necessary to set the carrier frequency higher in order to carry out stable control. Synchronous PWM is an effective PWM pattern for that purpose. By changing the carrier frequency in synchronization with the fundamental wave frequency 33a1 of the first inverter 20a, it is possible to control a region where the fundamental wave frequency is high with one PWM pattern.

However, if synchronous PWM is performed even in a region where the fundamental wave frequency 33a1 is low, the carrier frequency becomes too low, which may cause control failure. Therefore, in a region where the fundamental wave frequency is low, stable control can be performed by using asynchronous PWM that sets the carrier frequency constant. FIG. 3 shows an example in which two PWM patterns, asynchronous PWM and synchronous PWM, are set as a combination pattern according to a change in the fundamental wave frequency.

FIG. 4 is an example showing two combination patterns of PWM patterns that are switched according to the output current 33a2 of the first inverter 20a as the input / output state 33a. At this time, there are two PWM patterns due to the difference in carrier frequency of asynchronous PWM. By switching the PWM pattern according to the output current 33a2, the carrier frequency can be set high in a state where the output current 33a2 is large, and more stable PWM control can be performed.

In the embodiment of the present application, the first PWM pattern determination unit 32a and the second PWM pattern determination unit 32b are provided with different PWM pattern combination patterns, and the carrier frequencies overlap between the first and second inverters. I'm reducing it. Each of the first and second PWM pattern determination units 32a and 32b selects one of the suitable combination patterns according to the characteristics of the first and second rotating machines 1a and 1b to be controlled. Then, PWM control is performed. Therefore, various combination patterns are assumed as combinations of PWM patterns, and the combination patterns thereof will be described.

Setting the carrier frequency of asynchronous PWM to a different value is also a different PWM pattern. Setting the number of pulses of synchronous PWM to a different number of pulses can also be said to be a combination pattern of different PWM patterns. FIG. 5 is an example of a combination pattern of PWM patterns different from that of FIG. 3, and the carrier frequency of asynchronous PWM is lower than that of FIG. 3, and the gradient of the carrier frequency increase with respect to the fundamental wave frequency 33a1 in the synchronous PWM region is large. This is an example. Further, in FIG. 3, the value of the fundamental wave frequency 33a1 for switching the PWM pattern from asynchronous PWM to synchronous PWM is different between the threshold value a and the threshold value b.

If the inverter 20a continues to operate at the same carrier frequency, noise of a specific frequency will be generated even with the inverter alone. Therefore, a technique of randomly changing the carrier frequency within a specific frequency range is known as a noise reduction method. Random PWM that randomly changes the carrier frequency in a specific frequency range may be used as the PWM pattern to be set. FIG. 6 shows an example of switching between random PWM and non-random PWM PWM patterns as a combination pattern according to a change in the fundamental wave frequency 33a1.

The first and second inverters 20a and 20b and the first and second rotors 1a and 1b are set to be paired, respectively, and an appropriate carrier frequency is set according to the parameters due to the characteristics unique to the rotor. Will also change. Therefore, when trying to set an appropriate carrier frequency for each of the first and second rotating machines 1a and 1b, it is more efficient to set different PWM patterns than to set them as a common PWM pattern. It becomes possible to control well. Therefore, the combination patterns of the PWM patterns are changed to have different settings so that the PWM patterns set by the plurality of inverters do not match at all.

FIG. 7 shows an example of setting the carrier frequency for the fundamental wave frequencies 33a1 and 33b1 of the first and second inverters 20a and 20b, respectively. Each of the PWM pattern determination units 32a and 32b has two patterns, asynchronous PWM and synchronous PWM, and the timing at which the PWM patterns are switched is set to be different between the two inverters. FIG. 8A shows an operation flow of the first PWM pattern determining unit 32a that determines the PWM pattern of the first inverter 20a of FIG. 7. In step S11, it is determined whether the fundamental wave frequency 33a1 of the first inverter 20a is smaller than the threshold value a, and in step S12, the PWM pattern a to be asynchronous PWM is selected. If the fundamental wave frequency of the inverter is equal to or higher than the threshold value a, step S13. Select the PWM pattern b to be the synchronous PWM with. Similarly, FIG. 8B shows an operation flow of the second PWM pattern determination unit 32b that determines the PWM pattern of the second inverter 20b of FIG. 7. In step S21, it is determined whether the fundamental wave frequency 33b1 of the inverter 20b is smaller than the threshold value b, and in step S22, the PWM pattern b to be asynchronous PWM is selected. Select the PWM pattern b to be the synchronous PWM.

The number of combined PWM patterns may be any number as long as it is two or more for each inverter, and FIG. 9 shows a case where each of the first inverter 20a and the second inverter 20b has four PWM patterns. The figure shows an example of a combination pattern in which the PWM pattern is switched according to the fundamental wave frequencies 33a1 and 33b1.

FIG. 10 is an operation flow for explaining the operation of the first PWM pattern determination unit 32a using the first inverter 20a as an example, and shows the output current 33a2 and the fundamental wave frequency 33a1 as the input / output states 33a for determining the PWM pattern. An example of switching between four PWM patterns a to d by combining two types of parameters is shown. First, in step S31, it is determined whether or not the output current 33a2 is larger than the threshold value a. If the determination result is smaller than the threshold value a, the PWM pattern is switched to the PWM pattern a in step S33 and to the PWM pattern b in step S34 according to the result of further comparing the fundamental wave frequency 33a1 with the threshold value b in step S32. When the output current 33a2 is equal to or higher than the threshold value a in step S31, the PWM pattern is added to the PWM pattern c in step S36 and the PWM pattern d in step S37 according to the result of comparing the fundamental wave frequency 33a1 with the threshold value c in step S35. Switch.

As described above, in the control of FIG. 10, the PWM pattern can be finely set according to the change of both the output current 33a2 and the fundamental wave frequency 33a1, and it is more appropriate according to the state of the first inverter 20a and the first rotating machine 1a. PWM pattern can be set.

In FIG. 11, by setting different PWM patterns for both the first and second inverters 20a and 20b, a carrier frequency region that is used only by the second inverter 20b and not used by the first inverter 20a is created. Shows that is possible. There is a concern that switching noise will increase if the PWM patterns overlap, but the combination pattern can be set so that the PWM patterns of multiple inverters do not overlap for a specific carrier frequency region for which noise reduction is desired. .. By doing so, it becomes possible to prevent the increase of noise in the region of the carrier frequency for which noise reduction is desired.

As described above, the rotary machine control device 100 of the first embodiment has a carrier frequency that changes according to the input / output states 33a and 33b of the first and second inverters 20a and 20b, respectively. The relationship is set as one PWM pattern, a combination pattern of two or more PWM patterns is provided according to the regions of the respective input / output states 33a and 33b, and the PWM combined for each of the first and second inverters 20a and 20b. The patterns are set to be different, and the first and second PWM pattern determination units 32a and 32b for switching the PWM pattern according to the respective input / output states 33a and 33b are provided.

With this configuration, two or more PWM patterns can be set for each of the first and second inverters 20a and 20b, and reduction of switching loss and reduction of current ripple are taken into consideration according to the region of the input / output state. By setting the PWM pattern, stable PWM control can be performed. Further, since the combination pattern combined for each of the first and second inverters 20a and 20b is different, it is possible to reduce noise due to the overlap of carrier frequencies between the first inverter 20a and the second inverter 20b. can.

Further, the PWM pattern can be set so that the specific carrier frequency regions do not overlap between the first and second inverters 20a and 20b, respectively, and the carrier frequency region for which noise reduction is desired can be achieved. It is possible to prevent the increase of noise.

Embodiment 2.
In the second embodiment, the rotary machine control device 100 including the plurality of first and second inverters 20a and 20b shown in FIG. 1 and the first and second rotary machines 1a and 1b driven by the rotary machine control device 100 are provided. The setting of the PWM pattern in consideration of noise reduction of the entire mounted system (for example, the entire mounted vehicle) will be described.

When setting the PWM pattern, the frequency domain for avoiding noise is set for each of the first and second inverters 20a and 20b, respectively. The carrier frequency region for avoiding noise may be determined from the frequency region in which noise is likely to increase for the entire system equipped with the configuration of FIG. 1. If the first inverter 20a and the second inverter 20b operate in the same carrier frequency PWM pattern in the frequency domain where noise should be avoided in the entire system, PWM switching noise overlaps and the system as a whole noise. There is a concern that it will grow more. Therefore, by setting a combination pattern of PWM patterns for each of the first and second inverters 20a and 20b so that the regions of the carrier frequencies to be avoided do not overlap, it is possible to prevent the noise increase of the entire system.

In FIG. 12, the carrier frequency region in which noise is avoided in the entire system is avoided by both the first inverter 20a and the second inverter 20b. By avoiding the carrier frequency region to be avoided by all inverters if possible, it is possible to prevent the increase of noise in the carrier frequency region.

However, if the PWM pattern appropriately set according to the input / output state of the first inverter 20a and the second inverter 20b overlaps with the carrier frequency region in which noise should be avoided in the entire system, all of them overlap. If an inverter tries to avoid the same carrier frequency region, there is a concern that it will not operate efficiently.

FIG. 13 shows an example of setting a PWM pattern when only the second inverter 20b avoids the frequency domain for avoiding noise as compared with FIG. 12. By setting only one inverter to avoid noise in the frequency domain for avoiding noise as a whole system, it is possible to operate efficiently and to reduce noise.

The inverter that avoids the noise of the entire system may be only one of a plurality of inverters, or may be avoided by all the inverters. If the number of inverters to be avoided is increased one by one and noise reduction is achieved to the desired noise magnitude, the remaining inverters will be able to create an efficient PWM pattern combination pattern without worrying about the carrier frequency region to be avoided. By setting it, it is desirable because it has a target noise reduction effect and enables efficient operation.

According to the present embodiment, in addition to the PWM pattern according to the input / output state of the inverter set in the first embodiment, the reduction of noise generated assuming the entire system equipped with the configuration of FIG. 1 is also considered. A combination pattern of PWM patterns can be set. In addition, the entire system can be operated with high efficiency and low noise.

In the first embodiment and the second embodiment, as shown in FIG. 1, the system configuration of each of the first inverter 20a and the second inverter 20b, the first rotating machine 1a, and the second rotating machine 1b is configured. Although the rotary machine control device 100 in the case has been described, the number of inverters and rotary machines may be a plurality of three or more, and even in these cases, the same effect can be obtained.

Although the present application describes various exemplary embodiments and examples, the various features, embodiments, and functions described in one or more embodiments are applications of a particular embodiment. It is not limited to, but can be applied to embodiments alone or in various combinations. Therefore, innumerable variations not illustrated are envisioned within the scope of the techniques disclosed herein. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments. ..

1a 1st rotary machine, 1b 2nd rotary machine, 20a 1st inverter, 20b 2nd inverter, 30a 1st inverter control unit, 30b 2nd inverter control unit, 31a 1st PWM control unit, 31b 2nd PWM control unit, 32a 1st PWM pattern determination unit, 32b 2nd PWM pattern determination unit, 33a, 33b input / output state, 33a1, 33b1 fundamental wave frequency, 33a2, 33b2 output current, 100 inverter control Device, 201 processor, 202 storage device

Claims (8)

It is a rotary machine control device having a plurality of inverters controlled by PWM.
The relationship between the input / output state of the inverter and the carrier frequency is set as one PWM pattern.
It has a combination pattern in which two or more of the PWM patterns are combined according to the region of the input / output state.
A rotary machine control device including a PWM pattern determining unit that switches the PWM pattern according to the combination pattern that is different for each inverter. The rotary machine control device according to claim 1, wherein the combination pattern does not overlap the regions of a specific carrier frequency among the plurality of inverters. The rotary machine control device according to claim 1 or 2, wherein the input / output state is the fundamental wave frequency of the inverter. The rotary machine control device according to claim 1 or 2, wherein the input / output state is the output current of the inverter. The rotary machine control device according to claim 1 or 2, wherein the PWM pattern combined as the combination pattern is synchronous PWM and asynchronous PWM. The rotary machine control device according to claim 1 or 2, wherein the PWM pattern combined as the combination pattern is a random PWM and a non-random PWM. The combination pattern in which the PWM patterns are combined according to any one of claims 1 to 6, wherein a region of a carrier frequency for avoiding noise is commonly set in the plurality of inverters. The rotating machine control device described. The rotation according to any one of claims 1 to 6, wherein a carrier frequency region for avoiding noise is set for each of the inverters in the combination pattern in which the PWM patterns are combined. Machine control device.

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