Rotating electrical machine control device

Abstract

When a plurality of PWM-controlled inverters are operated in parallel, if the range of the carrier frequency is limited in each inverter in order to reduce noise, there is a problem that the switching loss of the motor using a higher carrier frequency is always worsened, and the current ripple of the motor using a lower carrier frequency is always worsened. The rotary electric machine control device of the present invention sets the relationship between the input / output state of the inverter and the carrier frequency as one PWM mode, has a combination mode obtained by combining two or more of the PWM modes according to the range of the input / output state, and has a PWM mode determination unit that switches the PWM mode according to the different combination modes in each of the inverters.

Description

Technical Field

[0001] The present application relates to a rotating electrical machine control device. Background Art

[0002] When multiple inverters are operated in parallel, the relationship between the input and output state of the inverter and the carrier frequency, i.e., the PWM mode, is usually set to be common among the multiple inverters. However, if the carrier frequencies of the multiple inverters are the same, the noise generated by the switching of the inverter elements overlaps, causing the noise to increase.

[0003] As a countermeasure to the above problem, there is known a technique such as the following Patent Document 1. Patent Document 1 discloses that the noise generated by switching of inverter elements is reduced by setting the carrier frequencies having a specific bandwidth so as not to overlap between a plurality of inverters.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2011 / 135687 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The rotating electrical machine control device based on PWM control has the following problems: if the carrier frequency becomes higher, the switching loss caused by PWM control increases, and if the carrier frequency becomes lower, the current ripple worsens and the control becomes unstable. In order to perform stable PWM control, the setting of the PWM mode needs to take into account the switching loss and current ripple, and it is necessary to make appropriate settings so that the switching loss and current ripple do not increase depending on the base frequency or output current of the inverter.

[0009] However, the rotating electrical machine control device described in Patent Document 1 has the following problems: if only the reduction of noise is focused on, the switching loss of the motor using a high carrier frequency always worsens, and the current ripple of the motor using a low carrier frequency always worsens.

[0010] The present application is based on the above-mentioned problems, and its object is to obtain a rotating electrical machine control device that can perform stable PWM control taking into account the reduction of switching loss and current ripple when operating a plurality of inverters in parallel, and strive to achieve noise reduction.

[0011] Technical solutions adopted to solve technical problems

[0012] The rotating electrical machine control device involved in the present application is a rotating electrical machine control device having multiple inverters controlled by PWM. The rotating electrical machine control device sets the relationship between the input and output states of the inverters and the carrier frequency as one PWM mode, has a combination mode obtained by combining two or more of the PWM modes according to the area of ​​the input and output states, and has a PWM mode determination unit that switches the PWM mode according to the combination mode that is different in each of the inverters.

[0013] Effects of the Invention

[0014] According to the rotary electric machine control device of the present application, two or more PWM modes can be set in each inverter, so that stable PWM control can be performed by switching to an appropriate PWM mode according to the region of the input and output state. In addition, the combined mode obtained by combining the PWM modes in each inverter is different, so the noise caused by the overlap of the carrier frequency between the inverters can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a diagram showing a configuration of a rotating electrical machine control device according to the first embodiment.

[0016] Figure 2 This is a diagram for explaining a processing circuit of the inverter control unit according to the first embodiment.

[0017] Figure 3 This is a diagram showing a setting example of a PWM pattern based on the fundamental wave frequency of the inverter according to the first embodiment.

[0018] Figure 4 This is a diagram showing a setting example of a PWM pattern based on an output current of the inverter according to the first embodiment.

[0019] Figure 5 This is a diagram showing a setting example of a PWM pattern based on the fundamental wave frequency of the inverter according to the first embodiment.

[0020] Figure 6 This is a diagram showing a setting example of a PWM pattern using random PWM of the inverter according to the first embodiment.

[0021] Figure 7 This is a diagram showing a setting example of a PWM pattern among a plurality of inverters according to the first embodiment.

[0022] Fig. 8A This is a flowchart showing the operation based on the PWM pattern of the inverter according to the first embodiment.

[0023] Figure 8BThis is a flowchart showing the operation based on the PWM pattern of the inverter according to the first embodiment.

[0024] Fig. 9 This is a diagram showing a setting example of a PWM pattern among a plurality of inverters according to the first embodiment.

[0025] Fig.10 This is a flowchart showing the operation based on the PWM pattern of the inverter according to the first embodiment.

[0026] Fig.11 This is a diagram showing a setting example of a PWM pattern based on the fundamental wave frequency of the inverter according to the first embodiment.

[0027] Fig.12 This is a diagram showing a setting example of a PWM pattern among a plurality of inverters according to the first embodiment.

[0028] Fig.13 This is a diagram showing a setting example of a PWM pattern among a plurality of inverters according to the first embodiment. DETAILED DESCRIPTION

[0029] Implementation method 1.

[0030] The inverter and the rotating electric machine according to the first embodiment will be described with reference to the drawings. Figure 1 1 is a diagram showing a structure of a rotating electrical machine control device including a plurality of inverters and a plurality of rotating electrical machines driven by the inverters according to the present embodiment. In the following description of the embodiment, an example is given in which there are two inverters and two rotating electrical machines driven by the inverters.

[0031] For example, the first rotating motor 1a is a permanent magnet synchronous rotating motor with a stator having a multi-phase (three-phase in this example) winding and a rotor having a permanent magnet, and the second rotating motor 1b is a permanent magnet synchronous rotating motor with a stator having a multi-phase (three-phase in this example) winding and a rotor having a permanent magnet.

[0032] The rotating electrical machine control device 100 includes a first inverter 20a for driving the first rotating electrical machine 1a and a first inverter control unit 30a for controlling the first inverter 20a. The rotating electrical machine control device 100 includes a second inverter 20b for driving the second rotating electrical machine 1b and a second inverter control unit 30b for controlling the second inverter 20b.

[0033] The first inverter 20a 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 winding of the first rotating electrical 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 winding of the second rotating electrical machine 1b, and has a plurality of switching elements. The first and second inverters 20a and 20b are provided with a series circuit corresponding to the winding of each phase, and the series circuit is connected in series with a switching element on the positive side connected to the positive side of the DC power supply and a switching element on the negative side connected to the negative side of the DC power supply. The connection point of the two switching elements in each series circuit is connected to the winding of the corresponding phase of each of the first and second rotating electrical machines 1a and 1b. The first and second inverters 20a and 20b each have 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 the effective value of the three-phase AC current.

[0034] As the switching element, an IGBT (Insulated Gate Bipolar Transistor) with a diode connected in reverse parallel, a bipolar transistor with a diode connected in reverse parallel, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), etc. are used. The gate terminal of each switching element is connected to the first and second PWM control units 31a and 31b respectively provided in the first and second inverter control units 30a and 30b via a gate drive circuit, etc. Thus, each switching element is turned on or off by the first and second PWM control units 31a and 31b respectively provided in the first and second inverter control units 30a and 30b.

[0035] The first inverter control unit 30a has a first PWM control unit 31a and a first PWM mode determination unit 32a. The first PWM control unit 31a generates an AC voltage pattern of a three-phase AC that is expanded so that the phases of the sine waves of the fundamental frequency are shifted by 120 degrees, based on the fundamental frequency provided to the first inverter control unit 30a as a command value. The AC voltage pattern of each phase of the above-mentioned AC voltage is compared with a carrier (for example, a triangular wave) generated according to the carrier frequency indicated by the PWM mode 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 mode determination unit 32a based on the input-output state 33a input to the first inverter control unit 30a as sensing information. The details are explained later.

[0036] The second inverter control unit 30b has a second PWM control unit 31b and a second PWM mode determination unit 32b. The second PWM control unit 31b generates an AC voltage pattern of a three-phase AC that is expanded so that the phases of the sine waves of the fundamental frequency are shifted by 120 degrees, based on the fundamental frequency provided to the second inverter control unit 30b as a command value. The AC voltage pattern of each phase of the above-mentioned AC voltage is compared with a carrier (for example, a triangular wave) generated according to the carrier frequency indicated by the PWM mode 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 mode determination unit 32b according to the input-output state 33b input to the second inverter control unit 30b as sensing information. The details are explained later.

[0037] The first inverter control unit 30a and the second inverter control unit 30b are as follows Figure 2 As shown, the processing circuit is provided with a processor 201 and a storage device 202 as the core, and the processing of each part is realized by the processing circuit. As the processing circuit, it can include ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), various logic circuits and various signal processing circuits.

[0038] The first inverter control unit 30a includes the first inverter 20a and the first rotating motor 1a, and collects information on the input and output state 33a from various devices and sensors. For example, the command value provided to the first inverter control unit 30a, that is, the fundamental frequency 33a1, and the output current 33a2 of the first inverter 20a. The fundamental frequency 33a1 is a command value proportional to the rotation speed of the first rotating motor 1a, and can replace the rotation speed sensed from the first rotating motor 1a. In addition, the output current 33a2 is input to the first inverter control unit 30a as the effective value of the output current of each phase of the above-mentioned first inverter 20a. This current value can replace the current value of the DC power supply provided to the first inverter 20a. In addition, the output current 33a2 can be the current of the torque component or the current amplitude.

[0039] The second inverter control unit 30b includes the second inverter 20b and the second rotating motor 1b, and collects information on the input and output state 33b from various devices and sensors. For example, the command value provided to the second inverter control unit 30b, namely the fundamental frequency 33b1, and the output current 33b2 of the second inverter 20b. The fundamental frequency 33b1 is a command value proportional to the rotation speed of the second rotating motor 1b, and can replace the rotation speed sensed from the second rotating motor 1b. In addition, the output current 33b2 is input to the second inverter control unit 30b as the effective value of the output current of each phase of the second inverter 20b. This current value can replace the current value of the DC power supply provided to the second inverter 20b. In addition, the output current 33b2 can be the current of the torque component or the current amplitude.

[0040] Below, in Figures 3 to 6 In the present invention, the respective PWM modes provided in the first PWM mode determination unit 32a corresponding to the first inverter 20a and the second PWM mode determination unit 32b corresponding to the second inverter 20b are described. In either of the first and second PWM modes, there is no difference in the respective actions and functions of the first and second PWM mode determination units 32a and 32b for the respective input and output states 33a and 33b. Therefore, in the following description, unless otherwise specified, the first PWM mode determination unit 32a and its input and output state 33a are used as an example for description.

[0041] Figure 3 An example is shown in which two PWM modes are set and the PWM mode is switched according to the fundamental frequency 33a1 of the first inverter 20a. The PWM modes at this time are two: asynchronous PWM and synchronous PWM. When the fundamental frequency 33a1 is low, the carrier frequency is kept constant, and when the carrier frequency is above the threshold a, the carrier frequency is increased in proportion to the increase in the fundamental frequency 33a1.

[0042] There are several restrictions when determining the PWM mode. First, when the carrier frequency is set higher, the period of the carrier becomes very fine, so PWM control can be performed in a state closer to a continuous waveform, and the stability of the control is improved. On the other hand, the number of switching times of the components based on PWM control increases, and the switching loss may increase. Conversely, if the carrier frequency is set lower, the switching loss decreases, but the control may become unstable. Therefore, there is a trade-off between switching loss and control stability in the setting of the carrier frequency, and it needs to be set appropriately.

[0043] As the fundamental frequency 33a1 of the first inverter 20a increases, the carrier frequency needs to be set higher in order to implement stable control. As an effective PWM mode for setting the carrier frequency higher, there is synchronous PWM. By changing the carrier frequency synchronously with the fundamental frequency 33a1 of the first inverter 20a, a region with a higher fundamental frequency can be controlled with one PWM mode.

[0044] However, if synchronous PWM is also implemented in the region where the fundamental frequency 33a1 is low, the carrier frequency will become too low, which may cause control failure. Therefore, in the region where the fundamental frequency is low, asynchronous PWM with a constant carrier frequency is used to implement stable control. An example of setting the two PWM modes of asynchronous PWM and synchronous PWM as a combination mode according to the change of the fundamental frequency is Figure 3 .

[0045] Figure 4 Two combination modes of PWM modes switched according to the output current 33a2 of the first inverter 20a are shown as examples of the input-output state 33a. At this time, the PWM modes are two due to the difference in the carrier frequency of the asynchronous PWM. By switching the PWM mode according to the output current 33a2, the carrier frequency can be set higher when the output current 33a2 is large, and more stable PWM control can be implemented.

[0046] In the embodiment of the present application, the first PWM mode determination unit 32a and the second PWM mode determination unit 32b have different PWM mode combination modes to reduce the overlap of carrier frequencies between the first and second inverters. According to the respective characteristics of the first and second rotating electrical machines 1a and 1b as the control objects, the first and second PWM mode determination units 32a and 32b respectively select any appropriate combination mode to implement PWM control. Therefore, various combination modes are assumed as the combination of PWM modes, and these combination modes are explained.

[0047] Setting the carrier frequency of the asynchronous PWM to different values ​​is also a different PWM mode. Setting the number of pulses of the synchronous PWM to different pulse numbers can also be called a different combination mode of the PWM mode. Figure 5 is with Figure 3 Examples of different PWM mode combinations, with Figure 3 Compared with the case of , it is an example as follows: the carrier frequency of the asynchronous PWM is low, and the slope of the carrier frequency increase relative to the fundamental frequency 33a1 in the synchronous PWM region is large. In addition, Figure 3 In FIG. 1 , the threshold a and the threshold b are made different for the value of the fundamental frequency 33a1 for switching the PWM mode from the asynchronous PWM to the synchronous PWM.

[0048] If the inverter 20a continues to operate at the same carrier frequency, the inverter alone will also generate noise of a specific frequency. Therefore, as a noise reduction method, there is a known technique for randomly changing the carrier frequency within a specific frequency range. As a PWM mode for setting, a random PWM that randomly changes the carrier frequency within a certain specific frequency range can be used. Figure 6 , a PWM mode in which random PWM and non-random PWM are switched according to a change in the fundamental frequency 33a1 is shown as an example of a combination mode.

[0049] The first and second inverters 20a and 20b are set to form a pair with the first and second rotating electrical machines 1a and 1b, respectively, and the setting of the appropriate carrier frequency also changes according to the parameters caused by the inherent characteristics of the rotating electrical machines. Therefore, when the appropriate carrier frequency is set according to the first and second rotating electrical machines 1a and 1b, respectively, the setting of different PWM modes can achieve more efficient control than setting a common PWM mode. Therefore, the combination mode of the PWM mode is changed to set different settings so that the PWM modes set in the plurality of inverters are not all the same.

[0050] Figure 7 , an example of setting the carrier frequency with respect to the fundamental frequency 33a1, 33b1 of each of the first and second inverters 20a, 20b is shown. Each PWM mode determination unit 32a, 32b has two modes, asynchronous PWM and synchronous PWM, and is set so that the timing of PWM mode switching is different in the two inverters. Fig. 8A In the Figure 7 The operation flow of the first PWM mode determination unit 32a of the PWM mode of the first inverter 20a is shown in FIG. In step S11, it is determined whether the fundamental frequency 33a1 of the first inverter 20a is less than the threshold a, and the PWM mode a of the asynchronous PWM is selected in step S12. If the fundamental frequency of the inverter is above the threshold a, the PWM mode b of the synchronous PWM is selected in step S13. Similarly, Figure 8B In the Figure 7 The operation flow of the second PWM mode determination unit 32b of the PWM mode of the second inverter 20b is shown in FIG. In step S21, it is determined whether the fundamental frequency 33b1 of the inverter 20b is less than the threshold value b, and the PWM mode b that becomes the asynchronous PWM is selected in step S22. If the fundamental frequency 33b1 of the inverter 20b is above the threshold value b, the PWM mode b that becomes the synchronous PWM is selected in step S23.

[0051] If the number of combined PWM modes in each inverter is 2 or more, it can be any number. Fig. 92 shows a case where there are four PWM modes in each of the first inverter 20a and the second inverter 20b. The figure shows an example of a combination mode of switching the PWM modes according to the fundamental wave frequencies 33a1 and 33b1.

[0052] Fig.10 The operation flow of the first PWM mode determination unit 32a is described by taking the first inverter 20a as an example, and the following example is shown: as the input-output state 33a for determining the PWM mode, the four PWM modes a to d are switched by combining two parameters of the output current 33a2 and the fundamental frequency 33a1. First, in step S31, it is determined whether the output current 33a2 is larger than the threshold value a. As a result of the determination, if it is smaller than the threshold value a, the fundamental frequency 33a1 is further compared with the threshold value b in step S32, and according to the result, the PWM mode is switched to the PWM mode a in step S33, and the PWM mode is switched to the PWM mode b in step S34. In addition, if the output current 33a2 is greater than the threshold value a in step S31, the fundamental frequency 33a1 is further compared with the threshold value c in step S35, and according to the result, the PWM mode is switched to the PWM mode c in step S36, and the PWM mode is switched to the PWM mode d in step S37.

[0053] As mentioned above, Fig.10 In the control, the PWM mode is set more finely according to the changes in both the output current 33a2 and the fundamental frequency 33a1, and the appropriate PWM mode can be set according to the states of the first inverter 20a and the first rotating electrical machine 1a.

[0054] Fig.11 The following is shown: by setting different PWM modes in 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 can be generated. When the PWM modes overlap, the switching noise may increase, but the combination mode can be set so that the PWM modes of multiple inverters do not overlap with respect to the region of the specific carrier frequency where noise reduction is desired. As a result, the increase of noise can be prevented in the region of the carrier frequency where noise reduction is desired.

[0055] As shown above, the rotating electrical machine control device 100 of embodiment 1 sets the relationship between the carrier frequencies that change according to the respective input-output states 33a, 33b as one PWM mode for each of the first and second inverters 20a, 20b, sets a combination mode of two or more PWM modes according to the regions of the respective input-output states 33a, 33b, and sets it so that the PWM mode combined for each of the first and second inverters 20a, 20b is different, and has first and second PWM mode determination units 32a, 32b that switch the PWM mode according to the respective input-output states 33a, 33b.

[0056] By configuring in this way, two or more PWM modes can be set for each of the first and second inverters 20a and 20b, and by setting the PWM mode taking into account the reduction of switching loss and the reduction of current ripple according to the region of the input and output state, stable PWM control can be performed. In addition, since the combination mode for each of the first and second inverters 20a and 20b is different, it is possible to reduce the noise caused by the overlap of the carrier frequency between the first inverter 20a and the second inverter 20b.

[0057] Furthermore, the PWM pattern can be set so that specific carrier frequency regions do not overlap between the first and second inverters 20a and 20b, thereby preventing an increase in noise in the carrier frequency region where noise reduction is desired.

[0058] Implementation method 2.

[0059] In the second embodiment, the setting of the PWM mode taking into account the noise reduction of the entire system (for example, the entire vehicle on which the system is mounted) is described. Figure 1 The illustrated rotating electrical machine control device 100 includes a plurality of first and second inverters 20a, 20b, and first and second rotating electrical machines 1a, 1b driven thereby.

[0060] When the PWM mode is set, a frequency region to avoid noise is set for each of the first and second inverters 20a and 20b. Figure 1 For the system as a whole having a structure of , the carrier frequency region to avoid noise can be determined by the frequency region where noise is likely to grow. If the first inverter 20a and the second inverter 20b operate in the PMW mode of the same carrier frequency in the frequency region to avoid noise as the system as a whole, the switching noise of PWM overlaps, and the noise of the system as a whole may further increase. Therefore, by setting a combination mode of PWM modes for each of the first and second inverters 20a and 20b so that the carrier frequency regions to be avoided do not overlap, the growth of noise as the system as a whole can be prevented.

[0061] Fig.12 In the embodiment, as a whole system, the region of the carrier frequency that avoids noise is avoided in both the first inverter 20a and the second inverter 20b. If possible, by avoiding the region of the carrier frequency that should be avoided in all inverters, the growth of noise in the region of the carrier frequency can be prevented.

[0062] However, when the PWM mode appropriately set according to the input and output states of the first inverter 20a and the second inverter 20b does not overlap with the carrier frequency regions where noise should be avoided in the entire system, if the same carrier frequency region is avoided in all inverters, efficient operation may not be possible.

[0063] Fig.13 In, with Fig.12 In contrast, an example of setting the PWM mode when only the second inverter 20b avoids the frequency region to avoid noise is shown. By setting only one inverter to avoid the frequency region to avoid noise as the system as a whole, the operation can be performed efficiently and noise can also be reduced.

[0064] The inverter to avoid noise as a whole system may be only one of multiple inverters, or may be avoided in all inverters. If the number of inverters to be avoided is increased one by one, and the noise reduction reaches the required noise level, the remaining inverters do not need to care about the avoided carrier frequency area, and by setting a combination mode of efficient PWM mode, the target noise reduction effect can be obtained and the operation can be performed efficiently, so it is more preferred.

[0065] According to this embodiment, in addition to the PWM mode that matches the input and output state of the inverter set in the first embodiment, it is also possible to set the inverter to be equipped with Figure 1 The combination mode of the PWM mode is also considered to reduce the noise generated by the overall system structure. In addition, the overall system can be operated efficiently and with low noise.

[0066] In implementation mode 1 and implementation mode 2, as Figure 1 As shown, the rotating electrical machine control device 100 is described for the case of a system structure with two first inverters 20a and two second inverters 20b, and two first rotating electrical machines 1a and two second rotating electrical machines 1b, but the number of inverters and rotating electrical machines may be more than three, and the same effect can be obtained in this case.

[0067] This application describes various illustrative embodiments and examples, but the various features, forms and functions described in one or more embodiments are not limited to the application of specific embodiments, and can be applied to the embodiments alone or in various combinations. Therefore, it can be considered that countless unillustrated variations are also included in the technical scope disclosed in the specification of this application. For example, it is assumed that at least one constituent element is deformed, added or omitted, and at least one constituent element is extracted and combined with constituent elements of other embodiments.

[0068] Description of symbols

[0069] 1a First rotating electrical machine

[0070] 1b Second rotating electrical machine

[0071] 20a First inverter

[0072] 20b Second inverter

[0073] 30a First inverter control unit

[0074] 30b Second inverter control unit

[0075] 31a First PWM control unit

[0076] 31b Second PWM control unit

[0077] 32a First PWM mode determination unit

[0078] 32b Second PWM mode determination unit

[0079] 33a, 33b Input and output status

[0080] 33a1, 33b1 fundamental frequency

[0081] 33a2, 33b2 Output current

[0082] 100 Rotating motor control device

[0083] 201 Processor

[0084] 202 storage device.

Claims

1. A rotating electrical machine control device having a plurality of inverters controlled by PWM, wherein: The relationship between the input and output state of the inverter and the carrier frequency is set to a PWM mode, A combination mode is provided by combining two or more of the PWM modes according to the region of the input / output state, A PWM mode determination unit is provided, the PWM mode determination unit switching the PWM mode according to the combination mode that is different in each of the inverters, The input / output state is at least one of the fundamental frequency and the output current of the inverter. The PWM modes combined as the combination mode are synchronous PWM and asynchronous PWM, or random PWM and non-random PWM.

2. The rotating electrical machine control device according to claim 1, characterized in that: In the combination mode, the carrier frequency regions for avoiding noise do not overlap between the plurality of inverters.

3. The rotating electrical machine control device according to claim 1 or 2, characterized in that: In the combination pattern obtained by combining the PWM patterns, a region of a carrier frequency for avoiding noise is set in common to the plurality of inverters.

4. The rotating electrical machine control device according to claim 1 or 2, characterized in that: In the combined pattern obtained by combining the PWM patterns, a carrier frequency region for avoiding noise is set in each of the inverters.

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