JP2020010460A - Inverter controller - Google Patents

Abstract

To suppress sound generated by a carrier signal from being recognized as noise.SOLUTION: An inverter controller includes: a motor command calculation unit; a carrier signal generation unit; and a PWM unit. The carrier signal generation unit sets a fundamental frequency Fc1 of a carrier signal based on an operating point of a motor to disperse a frequency of the carrier signal by a dispersion width ΔFc1 with the fundamental frequency Fc1 being a center. When the fundamental frequency Fc1 is in a low frequency range, each frequency of the carrier signal is dispersed so that a frequency of each frequency of the carrier signal to be dispersed is a normal distribution centered on the fundamental frequency. When the fundamental frequency is in a high frequency range, each frequency of the carrier signal is dispersed so that a frequency of each frequency of the carrier signal to be dispersed is a rectangular distribution centered on the fundamental frequency.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a configuration of an inverter control device, and more particularly, to dispersion control of a frequency of a carrier signal.

  A motor is driven by converting a DC power supply into an AC power supply by an inverter by PWM control. At this time, if the frequency of the carrier signal used for the PWM control is in the human audible band, it may be recognized as noise. For this reason, a method of randomly dispersing the frequency of the carrier signal to make noise less audible by making the noise white noise has been used (for example, see Patent Documents 1 and 2).

JP 2006-174645 A International Publication No. 2011/148481

  By the way, in recent years, a carrier signal of a low frequency may be used for the purpose of reducing the loss of the inverter and protecting the heat during downsizing. The frequency of the carrier signal is set to a frequency that does not resonate with the motor or the case, but in the low frequency range, frequencies at which resonance with the motor or the case occur near the frequency of the carrier signal. ing. For this reason, when the frequency of the carrier signal is dispersed, a sound different from a normal sound is generated due to resonance, which causes a problem that the sound is easily recognized as noise.

  In this regard, in the related art described in Patent Literature 1, when the frequency of the carrier signal is set to be low, the width of the frequency dispersion is narrowed to prevent resonance from occurring. However, in this method, there is a case where the vibration of the frequency in the human audible range is not sufficiently converted into white noise and is recognized as noise.

  Therefore, an object of the present invention is to suppress recognition of noise generated by a carrier signal as noise.

  An inverter control device of the present invention is an inverter control device for controlling an inverter including a plurality of switching elements, comprising: a motor command calculation unit that generates a control command for a voltage or a current supplied from the inverter to a motor; A plurality of switching elements of the inverter by PWM control based on the control command from the motor command calculation unit and the carrier signal from the carrier signal generation unit. A PWM section for performing an off operation, wherein the carrier signal generating section sets a fundamental frequency of the carrier signal based on an operating point of the motor, and sets the carrier signal in a predetermined frequency range around the fundamental frequency. And when the fundamental frequency is in the low frequency range, the Each frequency of the carrier signal is dispersed so that the frequency of each frequency of the carrier signal has a normal distribution centered on the fundamental frequency, and when the fundamental frequency is in a high frequency range, each of the carrier signals to be dispersed is dispersed. Each frequency of the carrier signal is dispersed such that the frequency of the frequency has a rectangular distribution centered on the fundamental frequency.

  ADVANTAGE OF THE INVENTION The inverter control apparatus of this invention can suppress that the sound generate | occur | produced by a carrier signal is recognized as noise.

It is a system diagram showing the composition of the motor control system using the inverter control device of an embodiment. FIG. 2 is a functional block diagram of the inverter control device shown in FIG. FIG. 3 is a waveform diagram illustrating PWM control by a PWM unit shown in FIG. 2. 4 is a flowchart illustrating an operation of the inverter control device according to the embodiment. 4 is a map for setting a fundamental frequency of a carrier signal from a motor operating point. FIG. 9 is a diagram illustrating the appearance frequency of each frequency when the fundamental frequency of the carrier signal is in a low frequency range, and the change in transmission sensitivity with respect to the frequency. FIG. 7 is a conceptual diagram showing the appearance frequency of each frequency with respect to time when the frequencies are dispersed as shown in FIG. 6. FIG. 9 is a diagram illustrating the appearance frequency of each frequency when the fundamental frequency of the carrier signal is in a high frequency range, and the change in transmission sensitivity with respect to the frequency. FIG. 9 is a conceptual diagram showing the appearance frequency of each frequency with respect to time when each frequency is dispersed as shown in FIG. 8.

  Hereinafter, the inverter control device 60 of the embodiment will be described with reference to the drawings. First, a motor control system 100 using an inverter control device 60 will be described with reference to FIG.

  As shown in FIG. 1, the motor control system 100 includes a motor 50, a DC power supply 20 including a battery or a battery and a boost converter, and a plurality of switching elements 33a to 35a and 33b to 35b. The inverter 30 includes an inverter 30 that converts DC power supplied from the inverter into AC power and supplies the AC power to the motor 50, and an inverter control device 60 that controls the inverter 30.

  A smoothing capacitor 31 for smoothing the voltage from the DC power supply 20 and a high voltage VH across the smoothing capacitor 31 are provided between the negative side electric circuit 11 on the input side of the inverter 30 (the side of the DC power supply 20) and the high-voltage piezoelectric path 13. Is provided. Further, between the negative electric path 11 on the opposite side of the DC power supply 20 of the smoothing capacitor 31 and the high piezoelectric path 13 opposed thereto, the upper arm switching elements 33a to 35a, Six switching elements of the lower arm switching elements 33b to 35b are arranged in series two by two for each phase. Output lines 55, 56, and 57 for each phase of U, V, and W are connected between each of the upper arm switching elements 33a to 35a and each of the lower arm switching elements 33b to 35b. The U, V, and W output lines 55, 56, and 57 are connected to the U, V, and W input terminals of the motor 50, respectively. Further, diodes 36a to 38a and 36b to 38b are connected in antiparallel to the upper arm switching elements 33a to 35a and the lower arm switching elements 33b to 35b of the U, V, and W phases, respectively. The inverter 30 turns on / off the six switching elements of the upper arm switching elements 33 a to 35 a and the lower arm switching elements 33 b to 35 b to convert DC power to AC power and supply the AC power to the motor 50.

  A current sensor 53 for detecting the current flowing through each output line 56, 57 and outputting it as current signals Iv, Iw is provided on two output lines 56, 57 for supplying V- and W-phase power from the inverter 30 to the motor 50. , 54 are mounted. A resolver 52 for detecting the number of rotations or the rotation angle θ of the rotor is attached to the motor 50. The inverter control device 60 includes therein a CPU 61, a storage unit 62, and a device / sensor interface 63 for connecting each device and sensor. The CPU 61, the storage unit 62, and the device / sensor interface 63 Computers connected by a data bus 64.

  Each of the switching elements 33a to 35a and 33b to 35b of the inverter 30 is connected to the inverter control device 60 via the device / sensor interface 63, and is configured to be driven by a command from the inverter control device 60. The V- and W-phase current sensors 53 and 54 and the resolver 52 attached to the motor 50 are connected to the device / sensor interface 63 of the inverter control device 60, respectively, and the current detected by each sensor, the rotation angle θ of the rotor, etc. Is input to the inverter control device 60 via the device / sensor interface 63.

  The inverter control device 60 stores a control program for controlling the inverter 30 and control data in the storage unit 62. As shown in FIG. 2, the inverter control device 60 has three functional blocks of a motor command calculation unit 65, a carrier signal generation unit 66, and a PWM unit 67 that operate by the cooperation of the CPU 61 and the storage unit 62. ing.

The motor command calculation unit 65 includes a torque command Trqcom of the motor 50 input from an external control device or another control block, current signals Iv and Iw detected by the current sensors 53 and 54, and a rotor signal detected by the resolver 52. Based on the rotation angle θ, the control command U, V, and W phase voltage commands V _U , V _V , and V _W are calculated and output to the PWM unit 67.

  The carrier signal generation unit 66 specifies the rotation speed of the motor 50 and the operating point of the torque based on the rotation speed of the rotor detected by the resolver 52 and the torque command Trqcom of the motor 50 and stores the map stored in the storage unit 62 (described later). The basic frequency Fc of the carrier signal is set based on the operating point of the motor 50 with reference to FIG. Further, the carrier signal generator 66 disperses the frequency of the carrier signal in a dispersion width that is a predetermined frequency range around the fundamental frequency Fc. Then, it outputs the dispersed carrier signals of the respective frequencies to the PWM unit 67. The vehicle speed is input from an external control device or another control block.

  The PWM unit 67 turns on / off the plurality of switching elements 33a to 35a and 33b to 35b of the inverter 30 by PWM control based on the voltage command from the motor command calculation unit 65 and the carrier signal from the carrier signal generation unit 66. Turn off.

  The PWM control of the inverter control device 60 will be briefly described with reference to FIG.

As shown in FIG. 3A, the angular frequency ω ₀ , the sine wave signals e _U , e _V , and e _W of the respective phases U, V, and W of the peak value V ₀ , and the angular frequency ω _{c as the} carrier signal compares the triangular carrier _{e c} of the peak value _{V c,} a, each phase of the upper arm switching element 33a of the inverter 30 shown in FIG. 1 by the amplitude of the magnitude, 34a, 35a and the lower arm switching elements 33b, 34b, 35b are alternately turned on / off. As a result, the voltages V _U , V _V , and V _W of the U, V, and W output lines 55, 56, and 57 with respect to the DC midpoint (the midpoint between the high piezoelectric path 13 and the negative electric path 11) are shown in FIG. As shown in FIG. 3D from FIG. 3B, it becomes either VH / 2 or −VH / 2, and the dashed line a, the two-dot chain line b, and the dashed line in FIG. 3B to FIG. A pulse train modulated like sine waves d, e, and f as shown in FIG. Further, the potential difference to become line voltage _{V UV} between the U-phase voltage _{V U} and V phase voltage _{V V,} as a sine wave h between the VH and -VH as shown in FIG. 3 (e) The result is a modulated pulse train g. Here, the frequency of the output sine wave signals _{e U,} e V, can be controlled by the angular frequency omega ₀ of _{e W,} the size thereof, a sine wave signal _{e U,} e V, _{e W} peak value V of it can be controlled by ₀ and the ratio of the peak value _{V c} of the triangular carrier _{e c (α = V 0 /} V c).

When the frequency of the triangular carrier e _c is the carrier signal is high, the number of switching times, alternating current waveform supplied to the motor 50 is closer to the sine wave, it is smooth control. On the other hand, since the number of times of switching increases, the switching loss increases and the amount of heat generated increases. On the other hand, when the frequency is low, the current waveform supplied to the motor 50 is shifted from the sine wave. However, since the number of times of switching is small, the switching loss is small and the heat generation is small.

Therefore, when the rotation speed of the motor 50 is high, using a triangular carrier e _c of the high frequency, when the rotation speed of the motor 50 is low, is often to use a triangular carrier e _c of the lower frequency . Further, there is a switching element 33a to 35a, even when the temperature of 33b~35b rises, to lower the frequency of the triangular carrier _{e c,} the case of suppressing the heat generation.

  Next, the operation of the inverter control device 60 of the present embodiment will be described with reference to FIGS. In addition, during the operation of the motor 50, the inverter control device 60 repeatedly executes steps S101 to S112 in FIG.

  As shown in step S101 of FIG. 4, the carrier signal generation unit 66 specifies the operating point of the motor 50 from the rotation speed of the rotor detected by the resolver 52 and the torque command Trqcom of the motor 50. In step S102 of FIG. 4, the carrier signal generation unit 66 determines whether or not the operating point specified in step S101 is within the range of the rotational speed and the torque at which the frequency of the carrier signal can be dispersed. If NO is determined in step S102 in FIG. 4, the process proceeds to step S112 in FIG. 4, and the carrier signal generation unit 66 ends the process without performing dispersion on the frequency of the carrier signal.

  On the other hand, if the determination is YES in step S102 of FIG. 4, the carrier signal generation unit 66 proceeds to step S103 of FIG. 4 and selects the fundamental frequency of the carrier signal with reference to the map shown in FIG. The map shown in FIG. 5 is a map in which the basic frequency is defined with respect to the rotation speed, output torque, and temperature of the motor 50.

  The map shown in FIG. 5 includes three areas A1, B1, C1 indicated by solid lines and three areas A2 indicated by broken lines, indicating an operation area surrounded by a maximum torque line p, an equal output line q, and a maximum speed line r. B2 and C2. The region A1 is a region where the rotation speed is low and the torque is large, the region B1 is a region where the rotation speed is large and the torque is small compared to the region A1, and the region C1 is a region where the rotation speed is a predetermined value or more or the output torque is a predetermined value or less. . The carrier signal generator 66 sets the low frequency Fc1 to the basic frequency when the operating point of the motor 50 is in the area A1, and sets the high frequency Fc3 to the basic frequency when the operating point is in the area C1. When the operating point is in the area B1, the medium frequency Fc2 is set as the fundamental frequency. Here, Fc1, Fc2, and Fc3 can take various values.

  The three areas A2, B2, and C2 indicated by broken lines in FIG. 5 are areas where the fundamental frequencies are set to Fc1, Fc2, and Fc3 when the temperatures of the switching elements 33a to 35a and 33b to 35b and the motor 50 rise. . The areas A2 and B2 are obtained by expanding the areas A1 and B1 to areas where the rotation speed is high and the output torque is small. The area C2 is obtained by reducing the area from the area C1 by the extension of the area B2. When the temperatures of the switching elements 33a to 35a and 33b to 35b and the motor 50 further rise, the areas A2 and B2 shown in FIG. 5 are expanded to the high-speed rotation area, and the area C2 is further reduced accordingly. Such a map may be used.

  When the fundamental frequency selected in step S103 is the low frequency Fc1, the carrier signal generation unit 66 determines YES (the fundamental frequency is in the low frequency range) in step S104 in FIG. 4 and determines in step S104 in FIG. Proceeding to S105, it is determined whether or not the vehicle speed is in a low speed region where the occurrence of abnormal noise is a concern. This low-speed region can be set variously depending on the type of vehicle. For example, the low-speed region may be set to 20 to 40 km / h or less.

  If YES is determined in step S105 of FIG. 4, the carrier signal generation unit 66 proceeds to step S106 of FIG. 4 and selects the normal distribution method. The normal distribution method is a control method for dispersing each frequency of the carrier signal so that each frequency of the carrier signal has a normal distribution centered on the fundamental frequency Fc1. Then, the carrier signal generation unit 66 determines the dispersion width ΔFc1 that is a predetermined frequency range from the fundamental frequency Fc1 in step S107 in FIG. 4, and determines the maximum frequency Fmax1 and the minimum frequency Fmin1 of the dispersion illustrated in FIG. I do. Then, the process proceeds to step S108 in FIG. 4 to determine a detailed frequency distribution from the fundamental frequency Fc1 and the dispersion width ΔFc1, and executes frequency dispersion control in step S109 in FIG.

  FIG. 7 shows an example of the detailed frequency distribution. As shown in FIG. 7, the frequency of a carrier signal is randomly varied at each time Δt so that the frequency of the number of times that a certain frequency continues for a time Δt has a normal distribution between the maximum frequency Fmax1 and the minimum frequency Fmin1. It is. As a result, noise generated by the frequency of the carrier signal is dispersed between the maximum frequency Fmax1 and the minimum frequency Fmin1, and the human perceives that the noise is reduced. The time Δt, each frequency of the carrier signal, and the dispersion width ΔFc1 are selected with reference to a map created in advance. In this case, the average value of each frequency of the carrier signal becomes the fundamental frequency Fc1.

  As shown in FIG. 6B, the fundamental frequency Fc1 is set to a frequency that does not resonate with the motor 50 or the like, and the vibration transmission sensitivity is low. Since the fundamental frequency Fc1 is a low frequency, frequencies where resonance with the motor 50 and the like occur are scattered near the fundamental frequency Fc1. For this reason, as shown in FIG. 6B, in a region where the frequency is slightly higher than the basic frequency Fc1 or in a region where the frequency is slightly lower, the vibration transmission sensitivity is high.

  The inverter control device 60 according to the present embodiment increases the frequency of appearance in the vicinity of the fundamental frequency Fc1 with low transmission sensitivity and disperses the frequency of the carrier signal so that the frequency of frequency in the region with high transmission sensitivity decreases. In addition, it is possible to suppress generation of noise due to resonance, and to suppress noise. Thereby, even when the frequency of the carrier signal is low, it is possible to suppress the sound generated by the carrier signal from being recognized as noise.

  On the other hand, when the high frequency Fc3 is selected as the fundamental frequency in step S103 of FIG. 4, the carrier signal generating unit 66 determines NO (the fundamental frequency is not in the low frequency range but in the high frequency range) in step S104 of FIG. Then, the process proceeds to step S110 in FIG. 4 to select the rectangular distribution method. The rectangular distribution method is a control method for dispersing each frequency of the carrier signal so that each frequency of the carrier signal has a rectangular distribution centered on the fundamental frequency Fc3. Then, the carrier signal generator 66 determines the dispersion width ΔFc3 which is a predetermined frequency range from the fundamental frequency Fc3 in step S111 in FIG. 4, and determines the maximum frequency Fmax3 and the minimum frequency Fmin3 of the dispersion shown in FIG. I do. Here, the dispersion width ΔFc3 may be the same frequency width as the dispersion width ΔFc1 described above, or may be a wider or narrower frequency width.

  In the frequency dispersion control in this case, as shown in FIG. 9, the frequency of the carrier signal is randomly changed at every time Δt, and the frequency of a certain frequency continuing for the time Δt is between the maximum frequency Fmax3 and the minimum frequency Fmin3. , So as to be evenly distributed in the range of the dispersion width ΔFc3. For this reason, the noise generated by the frequency of the carrier signal becomes white noise uniformly distributed between the maximum frequency Fmax3 and the minimum frequency Fmin3, and it feels as if the noise has been reduced. The time Δt, the frequency of the carrier signal, and the dispersion width ΔFc3 are selected with reference to a map created in advance. In this case, the average frequency of the carrier signal is the fundamental frequency Fc3.

  As shown in FIG. 8B, the fundamental frequency Fc3 is a high frequency that does not resonate with the motor 50 or the like. Therefore, there is no frequency region where resonance with the motor 50 or the like occurs near the fundamental frequency Fc3. The frequency region near the fundamental frequency Fc3 is a region where high-order fine film vibration of each device occurs. For this reason, as shown in FIG. 8B, there is no significant change in the transmission sensitivity of the vibration near the fundamental frequency Fc3, and even when the frequency of the carrier signal is dispersed with the dispersion width ΔFc3, the noise due to the resonance at a specific frequency is obtained. Does not occur.

  As described above, when selecting the fundamental frequency Fc3 in the frequency region where the transmission sensitivity does not greatly change, the inverter control device 60 of the present embodiment uniformly distributes the frequency of the carrier signal in the range of the dispersion width ΔFc3. Noise can be reduced as white noise. Thereby, it is possible to suppress the sound generated by the carrier signal from being recognized as noise.

  In addition, when the low frequency Fc1 or the intermediate frequency Fc2 is selected as the fundamental frequency in step S103 in FIG. 4, the carrier signal generation unit 66 determines YES in step S104 in FIG. Then, the process proceeds to step S105 in FIG. 4, and it is determined whether the vehicle speed is a vehicle speed at which abnormal noise is anxious. If YES is determined in step S105 of FIG. 4, the carrier signal generation unit 66 proceeds from step S106 of FIG. 4 to S109, and disperses the frequency of the carrier signal by the normal distribution method. On the other hand, if NO is determined in step S105 of FIG. 4, the carrier signal generation unit 66 proceeds to step S110 of FIG. 4 to disperse the carrier signal by the rectangular distribution method.

  In this way, when the vehicle speed is high and abnormal noise is difficult to hear due to background noise, the carrier signal is dispersed by the rectangular distribution method, and the sound generated by the carrier signal that is not easily mixed with the background noise is converted to white noise and recognized as noise. Can be suppressed.

  In the above embodiment, it is determined whether or not abnormal noise is difficult to hear due to background noise, based on the vehicle speed. However, the present invention is not limited to this, and abnormal noise can be heard due to background noise depending on the engine on / off or the engine speed. It may be determined whether it is difficult.

  As described above, the inverter control device 60 of the present embodiment can suppress the sound generated by the carrier signal from being recognized as noise.

  11 negative side electric circuit, 13 high piezoelectric circuit, 20 DC power supply, 30 inverter, 31 smoothing capacitor, 32 high voltage sensor, 33a-35a upper arm switching element, 33b-35b lower arm switching element, 36a-38a, 36b-38b diode, 50 motor, 52 resolver, 53, 54 current sensor, 55, 56, 57 output line, 60 inverter control device, 61 CPU, 62 storage unit, 63 device / sensor interface, 64 data bus, 65 motor command calculation unit, 66 carrier Signal generator, 67 PWM, 100 motor control system.

Claims (1)

An inverter control device that controls an inverter including a plurality of switching elements,
A motor command calculation unit that generates a control command of a voltage or a current supplied to the motor from the inverter,
A carrier signal generator for generating a carrier signal;
A PWM unit that turns on and off the plurality of switching elements of the inverter by PWM control based on the control command from the motor command calculation unit and the carrier signal from the carrier signal generation unit. ,
The carrier signal generator,
While setting the fundamental frequency of the carrier signal based on the operating point of the motor, dispersing the frequency of the carrier signal in a predetermined frequency range around the fundamental frequency,
When the fundamental frequency is in the low frequency range, the frequency of each frequency of the carrier signal to be dispersed is dispersed so that each frequency of the carrier signal has a normal distribution centered on the fundamental frequency,
When the fundamental frequency is in a high frequency range, dispersing each frequency of the carrier signal so that the frequency of each frequency of the carrier signal to be dispersed has a rectangular distribution centered on the fundamental frequency,
An inverter control device characterized by the above-mentioned.

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