JP2019201444A - Inverter controller and inverter control method - Google Patents

Abstract

To provide an inverter device capable of suppressing excessive ripple current generated by resonance in a DC side of an inverter driving a motor.SOLUTION: In a vehicle system 100, an inverter controller 36 for controlling an inverter 34 driving a motor 38 with PWM control comprises a control section where a carrier frequency of PWM control is changed so that a frequency of harmonic current generated on a DC side of the inverter 34 to which DC power is supplied from a power supply 10 is not included in a resonance frequency band determined in accordance with other units 44 and 54 connected in parallel to the inverter 34 with respect to the power supply 10 and the inverter 34.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inverter control device and an inverter control method.

  In patent document 1, it has the 1st vehicle-mounted electrical equipment provided with a power converter (for example, inverter), and the 2nd vehicle-mounted electrical device which shares a power supply with a 1st vehicle-mounted electrical apparatus while having a power converter similarly. In a vehicle, a protection device for an LC filter provided between a power converter and a power source of a first in-vehicle electric device is described. The protection device for the LC filter switches the resonance frequency band of the LC filter when the ripple amount of the current flowing through the power converter LC filter exceeds a specified value defined based on the withstand current of the capacitor. In this LC filter protection device, the carrier frequency of the power converter provided in the second in-vehicle electric device approaches the current resonance frequency band of the LC filter, and the ripple amount of the current flowing through the LC filter is lower than the specified value. When it becomes larger, the resonance frequency of the LC filter is switched. Thereby, the resonance frequency band of the LC filter is separated from the carrier frequency of the power converter provided in the second in-vehicle electric device, and an increase in the ripple amount is suppressed.

Japanese Patent No. 5673629

  However, since the protection device has a configuration including a plurality of capacitors, a plurality of coils, a plurality of switching elements, etc., in order to switch the resonance frequency band of the LC filter, the device is complicated, enlarged, increased in cost, etc. There is a problem. Therefore, there is a demand for a technique that suppresses an increase in the amount of current ripple while avoiding these problems.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

  According to one form of this invention, the inverter control apparatus (36) which controls the inverter (34) which drives an electric motor (38) by PWM control is provided. In this inverter control apparatus, the frequency of the harmonic current generated on the DC side of the inverter to which DC power is supplied from the power source (10) is connected to another device (44 , 54) and a control unit (370, 380, 390) for changing the carrier frequency of the PWM control so as not to be included in the forbidden band set from the resonance frequency band determined according to the circuit parameters between the inverter and the inverter Have

  According to this aspect, since the frequency of the harmonic current generated on the DC side of the inverter can be changed so that it is not included in the forbidden band set from the resonance frequency band, the carrier frequency of the PWM control can be changed. It is possible to suppress an increase in the amount of current ripple while avoiding problems such as technical complexity, enlargement, and cost increase. In addition, it is possible to suppress damage to the equipment due to the current exceeding the allowable current flowing through the inverter and other equipment connected in parallel.

  In addition, this invention can be implement | achieved with various forms, for example, can be implement | achieved with the form of an inverter control method other than an inverter control apparatus.

Explanatory drawing which showed typically the electric constitution of the system with which the inverter control apparatus of 1st Embodiment is applied. Explanatory drawing which shows the structure of an inverter control apparatus typically. The flowchart which shows the carrier frequency switching control routine performed with an inverter control apparatus. Explanatory drawing which shows an example of the change of the frequency of the harmonic component to generate | occur | produce. Explanatory drawing which shows an example of switching of a carrier frequency. Explanatory drawing which shows another example of switching of a carrier frequency. The flowchart which shows the carrier frequency switching control routine performed with the inverter control apparatus of 2nd Embodiment. Explanatory drawing which shows the prohibition zone | band and setting example of a carrier frequency. The flowchart which shows the carrier frequency switching control routine performed with the inverter control apparatus of 3rd Embodiment.

A. First embodiment:
Hereinafter, in the vehicle system 100 illustrated in FIG. 1, an example in which the inverter control device as one embodiment is applied to the inverter control device 36 of the travel inverter 34 that drives the travel motor 38 will be described.

  A travel motor drive unit 30, an A / C motor drive unit 40, and a power supply unit 50 are connected in parallel to the battery 10 as a power source of the vehicle system 100 via a power supply wiring 20. Yes. The travel motor drive unit 30 is a device that drives a travel motor (described as “TM” in FIG. 1) 38. The A / C motor drive unit 40 operates an A / C motor (not shown) (not shown) as an example of an auxiliary machine mounted as the vehicle system 100 (in FIG. 1). This is a device for driving 48). The power supply unit 50 is a device that converts the DC power supplied from the battery 10 into a voltage that can be supplied to a load 58 as another supplementary mounted as the vehicle system 100 and supplies the converted voltage.

  The travel motor drive unit 30 travels from the travel inverter 34 that controls the drive power of the travel motor 38 that generates power for the vehicle, the travel inverter control device 36 that controls the operation of the travel inverter 34, and the battery 10. And a filter 32 having a smoothing capacitor that smoothes the DC power supplied to the inverter 34. The traveling motor 38 is a three-phase AC motor. The traveling inverter control device 36 performs feedback control of the three-phase AC power that the traveling inverter 34 supplies to the traveling motor 38 so that the traveling motor 38 operates at the required operation amount (torque or rotation speed). At this time, the traveling inverter control device 36 is included in the traveling inverter 34 in order for the traveling inverter 34 to convert the direct current power from the battery 10 into three-phase alternating current power supplied to the traveling motor 38 and output it. The switching signal supplied to the switching element is controlled by pulse width modulation (PWM). The switching signal is a signal obtained by modulating the pulse width of a signal having a basic carrier frequency (hereinafter also referred to as “carrier frequency”) based on a change in a modulation wave having a modulation wave frequency according to the number of revolutions of the traveling motor 38. It is. Further, the traveling inverter control device 36 variably controls the carrier frequency based on the modulation wave frequency, as will be described later.

  The A / C motor drive unit 40 includes an A / C inverter 44 that controls the drive power of the A / C motor 48, an A / C inverter control device 46 that controls the operation of the A / C inverter 44, and And an LC filter 42 for smoothing the DC power supplied from the battery 10 to the A / C inverter 44. The A / C motor 48 is also a three-phase AC motor. As with the traveling inverter control device 36, the A / C inverter control device 46 is configured so that the A / C inverter 44 operates so that the A / C motor 48 operates at the required operation amount (torque or rotational speed). The three-phase AC power supplied to the A / C motor 48 is feedback-controlled. At this time, the A / C inverter control device 46 performs PWM control of the switching signal supplied to the switching element included in the traveling inverter 34, similarly to the traveling inverter control device 36.

  The power supply unit 50 includes a DC / DC converter 54 that converts DC power supplied from the battery 10 into a voltage that can be supplied to the load 58, and a DC / DC controller 56 that controls the operation of the DC / DC converter 54. And an LC filter 52 that smoothes the DC power supplied from the battery 10 to the DC / DC converter 54.

In this vehicle system 100,
(A) Between the traveling inverter 34 and the battery 10,
(B) Between the traveling inverter 34 and the A / C inverter 44,
(C) Between the traveling inverter 34 and the DC / DC converter 54,
, There may be a resonance frequency band in which circuit resonance occurs due to parasitic elements of wiring, capacitors, inductors, and the like constituting the filter. The A / C inverter 44 and the DC / DC converter 54 correspond to “other devices”.

Here, the current flowing on the DC side of the traveling inverter 34, that is, the DC power input side (DC side current) is expressed by the following equation (1) based on the PWM carrier frequency fc and the modulation wave frequency fe. The harmonic current of the nth order (n is an odd number) sideband harmonic component of the carrier wave and the mth order (m is an even number) harmonic component of the carrier wave expressed by the following equation (2) is generated (reference) Document: IEEJ Transaction D, Vol. 126, No. 7, 2006, pp. 1049-1057, “Theoretical Analysis of Sideband Harmonics of DC Current in Railway Vehicle Drive Inverters”).
n · fc ± 3 · fe Equation (1)
m · fc Formula (2)

  The closer the harmonic component is to the resonance frequency band existing between the circuits, the greater the amount of ripple of the DC side current. If the amount of ripple increases so as to exceed the allowable current of the device, the device will be damaged. In order to cope with such a problem, the traveling inverter control device 36 that controls the traveling inverter 34 has a configuration described below, thereby suppressing an increase in the ripple amount.

  As shown in FIG. 2, the traveling inverter control device 36 includes a difference detection unit 310, a current control unit 320, a coordinate conversion unit 330, a PWM unit 340, a current detection unit 350, a coordinate conversion unit 360, A rotation frequency calculation unit 370, a carrier frequency deriving unit 380, and a carrier frequency switching unit 390 are provided.

  The difference detection unit 310 is a difference between the d-axis current command Id * and the q-axis current command Iq * set according to the torque required for the traveling motor 38 and the measured d-axis current Id and q-axis current Iq. Is detected. The d-axis current Id and the q-axis current Iq are calculated by the coordinate conversion unit 360 from the three-phase currents Iu, Iv, and Iw flowing through the traveling inverter 34, as will be described later. However, since Iu + Iv + Iw = 0, the actually measured current may be a two-phase current among the three-phase currents. In this example, two-phase currents Iu and Iv are measured.

  The current control unit 320 generates a d-axis voltage command Vd * and a q-axis voltage command Vq * corresponding to the d-axis differential current ΔId and the q-axis differential current ΔIq. The coordinate conversion unit 330 outputs the d-axis voltage command Vd * and the q-axis voltage command Vq * to U, V, W based on the rotational displacement θ of the traveling motor 38 detected by the encoder 39 provided in the traveling motor 38. Are converted into three-phase voltage commands Vu *, Vv *, and Vw *.

  The PWM unit 340 includes three-phase switch signals Su, Sv, Sw in which the carrier pulse width of the carrier frequency fc output from the carrier frequency switching unit 390 is modulated based on the voltage commands Vu *, Vv *, Vw *. Is supplied to the traveling inverter 34.

  The travel inverter 34 supplies drive signals Vu, Vv, Vw to the travel motor 38 according to the switching pattern represented by the switch signals Su, Sv, Sw.

  The current detection unit 350 detects the current Iu flowing through the U-phase drive signal line using the current sensor 35u provided on the U-phase drive signal line, and the current sensor 35v provided on the V-phase drive signal line detects the current Iu. The current Iv flowing through the drive signal line is detected. The current detection unit 350 obtains the current Iw flowing through the W-phase drive signal line from Iw = − (Iu + Iv). The coordinate conversion unit 360 is based on the rotational displacement θ of the traveling motor 38 detected by the encoder 39 provided in the traveling motor 38, and the U, V, W three-phase d-axis voltage command Vd * and the q-axis voltage command. Vq * is converted into three-phase currents Iu, Iv, and Iw of U, V, and W into d-axis current Id and q-axis current Iq. Instead of obtaining the W-phase current Iw in the current detection unit 350, the coordinate conversion unit 360 may convert the two-phase currents Iu and Iv into the d-axis current Id and the q-axis current Iq. As described above, the d-axis current Id and the q-axis current Iq are used in the difference detection unit 310 to detect a difference between the d-axis current command Id * and the q-axis current command Iq *.

  As described above, the traveling inverter control device 36 includes the difference detection unit 310, the current control unit 320, the coordinate conversion unit 330, the PWM unit 340, the current detection unit 350, the coordinate conversion unit 360, and the traveling inverter 34. The operation of the traveling motor 38 is controlled by feedback control based on vector control executed by the encoder 39.

  Further, in the traveling inverter control device 36, the rotation frequency calculation unit 370, the carrier frequency deriving unit 380, and the carrier frequency switching unit 390 repeatedly execute the carrier frequency switching control routine shown in FIG. 3 together with the feedback control. Thus, the carrier frequency is variably controlled.

The rotation frequency calculation unit 370 calculates the modulation wave frequency fe according to the following expression (3) (step S10 in FIG. 3). The modulation wave frequency fe corresponds to an effective voltage fluctuation frequency represented by the PWM drive signals Vu, Vv, and Vw.
fe = P · fm Formula (3)
fm is the rotational frequency of the traveling motor 38, and is obtained from the change over time of the rotational displacement θ of the traveling motor 38 detected by the encoder 39. P is the number of pole pairs P of the traveling motor 38 (P is an integer of 1 or more).

  The carrier frequency deriving unit 380 is configured such that the frequency [n · fc ± 3 · fe] (formula (1)) and the frequency [m · fc] (formula (2)) of the harmonic component are resonant frequencies. When included in the band RFB (step S20 in FIG. 3: YES), the value of the carrier frequency fc to be changed is derived (step S30 in FIG. 3). The value of the carrier frequency fc to be changed is a value in which the frequency of the harmonic component generated according to the carrier frequency fc is not included in the resonance frequency band RFB. Then, carrier frequency deriving unit 380 outputs the derived value of carrier frequency fc to carrier frequency switching unit 390 as carrier frequency command fc *.

  The carrier frequency switching unit 390 switches the carrier signal to be output from the current carrier frequency fc value to a value corresponding to the carrier frequency command fc *, and outputs the carrier signal having the switched carrier frequency fc (FIG. 3). Step S40).

  On the other hand, the carrier frequency deriving unit 380 includes the harmonic component frequency [n · fc ± 3 · fe] (formula (1)) and frequency [m · fc] (formula (2)) in the resonance frequency band RFB. If not (step S20 in FIG. 3: NO), the value of the carrier frequency fc to be changed is not derived and the carrier frequency command fc * is not output. Also, the carrier frequency switching unit 390 does not switch the carrier frequency fc.

  As described above, the traveling inverter control device 36 has the harmonic component of the current generated on the DC side of the traveling inverter 34 by the rotation frequency calculating unit 370, the carrier frequency deriving unit 380, and the carrier frequency switching unit 390. The carrier frequency is controlled so as not to be included in the resonance frequency band RFB.

  Hereinafter, an example of control for changing the carrier frequency in the case of the resonance frequency and the harmonic component shown in FIG. 4 will be described. However, for ease of explanation, assuming that the rotation speed of the traveling motor 38 is in the range of 0 rpm to 18000 rpm and n is 1 and m is 2, the frequency of the harmonic component that changes according to the rotation speed [n For fc ± 3 · fe] (= [fc ± 3 · fe]) and frequency [m · fc] (= 2 · fc]), the carrier frequency fc is 4 kHz, 5 kHz, 6 kHz, 7 kHz, and 8 kHz, respectively. As an example. Further, as the resonance frequency band RFB, a case where a first resonance frequency band RFB1 of 5 kHz to 6 kHz and a second resonance frequency band RFB2 of 1 kHz to 3 kHz exist is taken as an example. Note that the frequency [m · fc] of harmonic components other than the carrier frequency fc of 4 kHz is much higher than the resonance frequency bands RFB1 and RFB2, and is not shown.

  As shown in Expression (3), the modulation wave frequency fe changes in proportion to the rotation frequency fm of the traveling motor 38. Therefore, as shown in FIG. 4, the frequency of the harmonic component [n · fc ± 3 · fe] changes in proportion to the rotational speed (60 · fm) [rpm]. Here, since the rotation frequency fm is expressed by fm = fe / P from the equation (3), the frequency [n · fc ± 3 · fe] of the harmonic component changes in proportion to the modulation wave frequency fe. The frequency [n · fc ± 3 · fe] of the harmonic component in FIG. 4 is shown as an example when the number of pole pairs P = 4.

  In the case of fc = 4 kHz, as indicated by the thick solid line, the harmonic component of the frequency [fc-3 · fe] is a frequency included in the second resonance frequency band RFB2 at a rotational speed of 5000 rpm to 15000 rpm, and the frequency [fc + 3 · The harmonic component of [fe] is a frequency included in the first resonance frequency band RFB1 at a rotational speed of 5000 rpm to 10,000 rpm. Similarly, at other frequencies fc = 5 kHz, 6 kHz, 7 kHz, and 8 kHz, the harmonic component of the frequency [fc ± 3 · fe] is generated in the resonance frequency bands RFB1 and RFB2 at the number of rotations corresponding to each change state. included.

  Therefore, when fc = 4 kHz, it is preferable not to set the carrier frequency fc to 4 kHz between the rotational speeds of 5000 rpm to 15000 rpm, as indicated by the thick solid line. Similarly, in the case of fc = 5 kHz, it is preferable not to set the carrier frequency fc to 5 kHz between the rotational speeds of 0 rpm to 5000 rpm and 10000 rpm to 18000 rpm, as indicated by the thick dashed line. In the case of fc = 6 kHz, it is preferable not to set the carrier frequency fc to 6 kHz between the rotational speeds of 0 rpm to 5000 rpm and 15000 rpm to 18000 rpm, as indicated by a thick two-dot chain line. In the case of fc = 7 kHz, it is preferable not to set the carrier frequency fc to 7 kHz between the rotational speeds of 5000 rpm to 10000 rpm as shown by the thick broken line. In the case of fc = 8 kHz, it is preferable not to set the carrier frequency fc to 8 kHz between the rotational speeds of 10000 rpm to 15000 rpm, as shown by the thick broken lines.

  Therefore, for example, as shown in FIG. 5, fc = 4 kHz can be set when the rotational speed is less than 5000 rpm, fc = 6 kHz when the rotational speed is 5000 rpm or more and less than 15000 rpm, and fc = 8 kHz when the rotational speed is 15000 rpm or more. As a result, the frequency [fc ± 3 · fe] of the generated harmonic component is changed as shown by the solid line, the thick two-dot chain line, and the thick broken line, and does not become the frequencies in the resonance frequency bands RFB1 and RFB2. Can be.

  For example, as shown in FIG. 6, fc = 7 kHz when the rotational speed is less than 5000 rpm, fc = 8 kHz when the rotational speed is 5000 rpm or more and less than 10,000 rpm, fc = 9 kHz when the rotational speed is 10,000 rpm or more and less than 15000 rpm, and 15000 rpm or more. Then, fc = 10 kHz can also be set. As a result, the frequency [fc ± 3 · fe] of the generated harmonic component is changed as shown by the thick solid line, the bold one-dot chain line, the thick two-dot chain line, and the thick dashed line, and the resonance frequency bands RFB1, RFB2 It is possible to prevent the frequency from being within.

  As described above, in the traveling inverter control device 36 of the first embodiment, the harmonic component frequency generated in the DC side current of the traveling inverter 34 is represented by the harmonics represented by the equations (1) and (2). It can be obtained with high accuracy based on the theoretical expression of the wave component. Then, the carrier frequency can be switched so that the frequency of the determined harmonic component is not included in the resonance frequency band. This suppresses an increase in the ripple amount of the DC current that occurs as the frequency of the harmonic component approaches the resonance frequency band, and the ripple amount increases as the device exceeds the allowable current, leading to damage to the device. Can be suppressed.

B. Second embodiment:
In the inverter control apparatus according to the second embodiment, switching control of the carrier frequency fc is executed in accordance with the carrier frequency switching control routine shown in FIG. The configuration of the system to which the inverter control device of the second embodiment is applied and the configuration of the inverter control device are the same as those of the first embodiment.

In the carrier frequency switching control routine of the second embodiment shown in FIG. 7, step S20 in FIG. 3 is replaced with step S20B. In step S20B, the carrier frequency deriving unit 380 determines whether the current carrier frequency fc is within the forbidden band PFB that satisfies the conditions expressed by the following equations (4) to (6).
[Fu / n + 3 · fc / n]>fc> [fl / n + 3 · fe / n] (4)
[Fu / n-3 · fc / n]>fc> [fl / n-3 · fe / n] (5)
[Fu / m]>fc> [fl / m] (6)
n is an odd number, m is an even number, fu is a maximum frequency in the resonance frequency band, and fl is a minimum frequency in the resonance frequency band.

  When the current carrier frequency fc is within the forbidden band PFB (step S20B: YES), the carrier frequency deriving unit 380 (see FIG. 2) changes the value of the carrier frequency fc to be outside the forbidden band PFB. (Step S30 in FIG. 7), and the derived carrier frequency fc value is output as a carrier frequency command fc * to the carrier frequency switching unit 390 (see FIG. 2). Then, the carrier frequency switching unit 390 switches the carrier frequency fc (step S40 in FIG. 7).

  On the other hand, when the carrier frequency fc is not included in the forbidden band PFB (step S20B: NO in FIG. 7), the carrier frequency deriving unit 380 derives the value of the carrier frequency fc to be changed and outputs the carrier frequency command fc *. Do not do. Accordingly, the carrier frequency switching unit 390 does not switch the carrier frequency fc.

  FIG. 8 shows an example of the forbidden band PFB of the carrier frequency fc. However, for ease of explanation, the maximum frequency fu of the resonance frequency band RFB is 6 kHz, the minimum frequency fl is 5 kHz, and n in the expressions (4) to (6) indicating the conditions of the forbidden band PFB is 1. The case where m is 2 is shown as an example.

  For example, as shown in the carrier frequency setting example, the carrier frequency fc may be set to a frequency having a value not included in the forbidden band PFB that satisfies the conditions of Expressions (4) to (6). In the carrier frequency setting example, fc = 4 kHz when the rotational speed is less than 5000 rpm, and fc = 5 kHz when the rotational speed is 5000 rpm or more. However, the present invention is not limited to this, and various values that are not included in the forbidden band PFB can be used.

  In the above description, for ease of explanation, the case of having one resonance frequency band RFB has been described as an example. However, in the case of having a plurality of resonance frequency bands RFB, an equation is provided for each resonance frequency band. The forbidden band PFB represented by (4) to (6) is set.

  As described above, in the traveling inverter control device 36 according to the second embodiment, the harmonics shown in the expressions (1) and (2) are used as the frequencies of the harmonic components generated in the DC side current of the traveling inverter 34. By using the theoretical expression of the wave component, the forbidden band of the carrier frequency that satisfies the conditions shown in Expressions (4) to (6) can be obtained with high accuracy. The carrier frequency can be switched so that the carrier frequency is not included in the obtained forbidden band. This suppresses an increase in the ripple amount of the DC current that occurs as the frequency of the harmonic component approaches the resonance frequency band, and the ripple amount increases as the device exceeds the allowable current, leading to damage to the device. Can be suppressed.

C. Third embodiment:
In the inverter control apparatus of the third embodiment, switching control of the carrier frequency fc is executed according to the carrier frequency switching control routine shown in FIG. The configuration of the system to which the inverter control device of the third embodiment is applied and the configuration of the inverter control device are the same as those of the first embodiment.

  In the carrier frequency switching control routine of the third embodiment shown in FIG. 9, step S20 in FIG. 3 is omitted, step S30 is replaced with step S30C, and step S35C is inserted between step S30C and step S40. Yes.

  In step S30C, the carrier frequency deriving unit 380 (see FIG. 2) determines the rotational frequency in step S10 from a map (not shown) indicating the relationship between the modulation wave frequency fe prepared in advance and the settable carrier frequency fc. A value of the carrier frequency fc corresponding to the modulation wave frequency fe obtained according to the equation (3) based on fm is derived. Then, the carrier frequency deriving unit 380 determines whether or not the carrier frequency fc needs to be changed in step S35C. Specifically, when the value of the derived carrier frequency fc is different from the current carrier frequency fc, it is determined that the change is necessary (step S35C: YES), and the carrier frequency deriving unit 380 determines the derived carrier frequency. The value of fc is output as a carrier frequency command fc * to the carrier frequency switching unit 390 (see FIG. 2). Then, the carrier frequency switching unit 390 switches the carrier frequency fc (step S40 in FIG. 9). On the other hand, if the derived carrier frequency fc is the same as the current carrier frequency fc, it is determined that the change is not necessary (step S35C: NO), and the carrier frequency command fc * is not output. Accordingly, the carrier frequency switching unit 390 does not switch the carrier frequency fc.

  The map used for deriving the value of the carrier frequency fc has a value of the carrier frequency fc that does not become a forbidden band satisfying the expressions (4) to (6) for the values of the plurality of modulation wave frequencies fe in advance. It can be created by obtaining (see FIG. 8).

  As described above, in the third embodiment, the harmonic component theoretical expression shown in the equations (1) and (2) is used as the frequency of the harmonic component generated in the DC side current of the traveling inverter 34. Thus, the forbidden band of the carrier frequency that satisfies the conditions shown in the equations (4) to (6) can be obtained with high accuracy. A relationship between the modulation wave frequency and the carrier frequency that is not included in the forbidden band can be obtained in advance. Thereby, in the inverter control apparatus 36 for driving | running | working of 3rd Embodiment, a carrier frequency is included in a prohibition band by calculating | requiring the carrier frequency corresponding to the modulation wave frequency calculated | required according to a rotation frequency from the map prepared beforehand. So that the carrier frequency can be switched. This suppresses an increase in the ripple amount of the DC current that occurs as the frequency of the harmonic component approaches the resonance frequency band, and the ripple amount increases as the device exceeds the allowable current, leading to damage to the device. Can be suppressed. Further, from the prepared map, the carrier frequency that can prevent the carrier frequency from being included in the forbidden band and the frequency of the harmonic component from being included in the resonance frequency band can be obtained in advance, and the processing time can be obtained. Can be shortened.

D. Other embodiments:
(1) In the above embodiment, the frequencies [n · fc + 3 · fc] and [n · fc−3 / fc] of the n-th order (n is an odd number) sideband harmonic of the carrier wave represented by the equation (1), The carrier frequency fc is changed so that the frequency [m · fc] of the m-th order (m is an even number) harmonic is not included in the resonance frequency band. However, the present invention is not limited to this. The carrier frequency fc may be changed so that one of the frequency [n · fc + 3 · fe] and the frequency [n · fc−3 · fe] is not included in the resonance frequency band. According to this, compared with the case where both the frequency [n · fc + 3 · fe] and the frequency [n · fc−3 · fe] are included in the resonance frequency band, the ripple amount of the DC side current of the inverter is reduced. can do. Further, the carrier frequency fc is set so that at least one of the frequency [n · fc + 3 · fe], the frequency [n · fc−3 · fe], and the frequency [m · fc] is not included in the resonance frequency band. It may be changed. According to this, compared with the case where the frequency [n · fc + 3 · fe], the frequency [n · fc−3 · fe], and the frequency [m · fc] are included in the resonance frequency band, the DC side of the inverter The amount of current ripple can be reduced.

(2) In the above embodiment, the harmonics having the frequencies represented by the equations (1) and (2) are generated as the harmonics generated depending on the carrier frequency fc. However, the present invention is not limited to this. It is not something. For example, it is also possible to use the frequency of the harmonic component using various logical expressions obtained by analyzing the generated harmonic component such as the harmonic component shown in the above-mentioned reference document.

(3) In the above embodiment, the case where the inverter control device of the invention is applied to the travel inverter control device 36 that controls the travel inverter 34 has been described as an example, but the A / C that controls the A / C inverter 44 is described. The inverter control device of the invention may be applied to the inverter control device 46 for C. That is, the present invention can be applied to an inverter control device that controls various inverters.

(4) In the inverter control apparatus of the above embodiment, the case where the electric motor is operated via the inverter by feedback control using vector control has been described as an example. In addition, V / f that outputs a voltage corresponding to the frequency is used. The invention of the present application is also applicable to the case where the electric motor is operated via an inverter by general feedback control using control.

  The present invention is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present invention. For example, the technical features of the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems, or part of the above-described effects. Or, in order to achieve the whole, it is possible to replace or combine as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

    DESCRIPTION OF SYMBOLS 10 ... Battery, 20 ... Wiring, 30 ... Traveling motor drive part, 32 ... Filter, 34 ... Traveling inverter, 36 ... Traveling inverter control apparatus, 38 ... Traveling motor, 40 ... A / C motor drive part, 42 ... LC Filter, 44 ... A / C inverter, 46 ... A / C inverter control device, 48 ... A / C motor, 50 ... Power supply unit, 52 ... LC filter, 54 ... DC / DC converter, 56 ... DC / DC Control device 58 ... Load 100 ... Vehicle system 310 ... Difference detection unit 320 ... Current control unit 330 ... Coordinate conversion unit 340 ... PWM unit 350 ... Current detection unit 360 ... Coordinate conversion unit 370 ... Rotation Frequency calculation unit, 380... Carrier frequency deriving unit, 390... Carrier frequency switching unit.

Claims (9)

An inverter control device (36) for controlling an inverter (34) for driving an electric motor (38) by PWM control,
The frequency of the harmonic current generated on the DC side of the inverter to which DC power is supplied from the power source (10) is connected to another device (44, 54) connected in parallel to the inverter with respect to the power source and the inverter An inverter control device having a control unit (370, 380, 390) that changes the carrier frequency of the PWM control so that it is not included in the resonance frequency band determined according to. The inverter control device according to claim 1,
The frequency of the harmonic current includes a frequency [n · fc + 3 · fe] (n is an odd number) represented by fc indicating the carrier frequency and fe indicating the modulation wave frequency of the PWM control, and a frequency [ n · fc−3 · fe] and frequency [m · fc] (m is an even number). The inverter control device according to claim 2,
The control unit is configured so that the frequency (n · fc + 3 · fe), the frequency (n · fc−3 · fe), and the frequency (m · fc) are not included in the resonance frequency band. An inverter control device that changes the carrier frequency. The inverter control device according to claim 3,
Forbidden bands set based on the resonance frequency band of frequency fl to frequency fu (fu> fl) are [fu / n + 3 · fe / n]>fc> [fl / n + 3 · fe / n], [fu / n-3 · fe / n]>fc> [fl / n-3 · fe / n], and [fu / m]>fc> [fl / m].
The said control part is an inverter control apparatus which changes the said carrier frequency so that it may not be contained in the said prohibition zone. The inverter control device according to claim 4,
A plurality of the resonance frequency bands,
The inverter control device, wherein the forbidden band is set based on at least one of the resonance frequency bands. The inverter control device according to claim 4 or 5, wherein
The control unit is an inverter control that changes the carrier frequency based on a predetermined relationship between a modulation wave frequency determined from a rotation frequency of the motor and a carrier frequency that satisfies a condition not included in the prohibited band. apparatus. The inverter control device according to claim 2,
The control unit changes the carrier frequency so that one of the frequency (n · fc + 3 · fe) and the frequency (n · fc−3 · fe) is not included in the resonance frequency band. . The inverter control device according to claim 2,
The inverter control device, wherein the control unit changes the carrier frequency so that the frequency (n · fc + 3 · fe) and the frequency (n · fc−3 · fe) are not included in the resonance frequency band. An inverter control method for controlling an inverter (34) for driving an electric motor (38) by PWM control,
The frequency of the harmonic current generated on the DC side of the inverter to which DC power is supplied from the power source (10) is connected to the power source in parallel with the inverter, the other device (44), and the inverter An inverter control method in which the carrier frequency of the PWM control is changed so that it is not included in the resonance frequency band determined according to (S10 to S40, S20B, S30C, S35C).

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