DE112020006657T5 - INVERTER CONTROL DEVICE AND ELECTRIC MOTOR DRIVE DEVICE - Google Patents

Abstract

An inverter control device (5) comprises a carrier wave generation unit (8) that generates three-phase carrier waves, and a PWM control unit (7) that controls a switching state of an inverter by comparing a carrier wave and a modulated wave. The carrier wave generation unit (8) includes a phase calculation unit (81) that calculates first to third carrier wave phases based on a carrier wave frequency command and an electric motor frequency, and a carrier wave output unit (82) that outputs the three-phase carrier waves based on the first to third carrier wave phases. The first to third carrier wave phases have phase differences from each other, and the phase difference changes continuously in accordance with a change in electric motor frequency.

Description

Area

The present disclosure relates to an inverter control device that controls an inverter and an electric motor driving device that includes the inverter control device.

background

Electric motors, which exert a driving force on electric vehicles, are driven or controlled by inverters. Track antenna beacons, which represent receivers of various signal types, are arranged on a track where electric vehicles are traveling. In order to prevent these track antenna beacons from malfunctioning, rules about leakage noise are set for the electric vehicles. Patent Literature 1 below describes that, in order to reduce leakage noise, a hollow core formed of a ferromagnetic material such as ferrite or an amorphous metal is placed around a wire connected to which connects the inverter and the electric motor.

quote list

patent literature

Patent Literature 1: Japanese Patent Application Laid-Open No. 2004-187368

summary

Technical problem

However, a space under a floor of an electric vehicle is limited. Therefore, in some cases, there is not enough space to additionally provide a filter component such as the cores described in Patent Literature 1 described above. In such a case, it is necessary in some cases to look through the descriptions of the inverter control devices in order to secure the space for additionally providing the filter component.

Furthermore, the filter characteristics of the filter component must be determined in accordance with impedance including that of an electric motor. However, the manufacturer of the electric motor and the manufacturer of the inverter control device are not necessarily the same. In this case, depending on additional provision of the filter component, the number of planning steps for the manufacturer of the inverter control device will increase and adjustment work will increase in practical vehicles. Therefore, it is desirable to reduce leakage noise without depending on providing an additional filter component.

The present disclosure is made in view of the above, and an object of the present disclosure is to provide an inverter control device that can reduce leakage noise without depending on providing an additional filter component.

Troubleshooting

In order to solve the above problems and achieve the object, the present disclosure relates to an inverter control device that controls an inverter that drives a three-phase electric motor by pulse width modulation. The inverter control device includes: a carrier wave generation unit for generating three-phase carrier waves; and a pulse width modulation controller for controlling a switching state of the inverter by comparing the carrier wave with a modulated wave. The carrier wave generation unit includes a phase calculation unit for calculating first to third carrier wave phases based on a carrier wave frequency command and an electric motor frequency, and a carrier wave output unit for outputting the three-phase carrier waves based on the first to third carrier wave phases. The first to third carrier wave phases have phase differences from each other, and the phase differences continuously change in accordance with a change in electric motor frequency.

Advantageous Effects of the Invention

The inverter control device according to the present disclosure produces an effect that leakage noise can be reduced without depending on providing an additional filter component.

character list

• 1 12 is a diagram illustrating an example configuration of an electric motor drive device including an inverter control device according to a first embodiment.
• 2 FIG. 12 is a diagram illustrating an example configuration of a general inverter main circuit.
• 3 represents a diagram showing an equivalent circuit in 1 illustrates which is used to explain a leakage current.
• 4 FIG. 12 is a diagram used for explaining a method of generating pulse width modulation (PWM) control signals provided to semiconductor elements of each arm shown in FIG 2 is illustrated.

• 5 FIG. 12 is a diagram illustrating PWM control signals generated in accordance with individual phase voltage commands given in FIG 4 are illustrated.
• 6 represents a diagram illustrating a common-mode voltage represented by the in 5 illustrated PWM control signals is generated.
• 7 FIG. 12 is a diagram illustrating an example of each phase voltage command with a modulation rate different from that in FIG 4 differs.
• 8th FIG. 12 is a diagram illustrating PWM control signals generated according to individual phase voltage commands given in FIG 7 are illustrated.
• 9 represents a diagram illustrating a common-mode voltage represented by the in 8th illustrated PWM control signals is generated.
• 10 12 is a diagram showing an example of waveforms in a case where carrier wave phases are shifted from respective phases by 120° from each other in a carrier wave and each in 7 illustrated phase voltage command.
• 11 FIG. 12 is a diagram illustrating PWM control signals generated by individual phase voltage commands and individual phase carrier waves, shown in FIG 10 are illustrated.
• 12 Figure 12 is a diagram illustrating an example of a common mode voltage waveform represented by the in 11 illustrated PWM control signals is generated.
• 13 12 is a diagram illustrating an example of harmonic distribution of an electric motor current according to conventional control when the carrier wave is the same in each phase.
• 14 12 is a diagram illustrating an example of the harmonic distribution of the electric motor current according to the conventional control in a case where the carrier wave phases of the respective phases are shifted from each other by 120°.
• 15 12 is a diagram showing an example of the common mode voltage waveform according to the conventional control in a case where the carrier wave phases of the respective phases are shifted by 120° from each other.
• 16 FIG. 14 is a diagram used for explaining a concept of a control method according to the first embodiment.
• 17 FIG. 14 is a diagram illustrating an exemplary configuration of a carrier wave generation unit according to the first embodiment.
• 18 12 is a diagram illustrating an exemplary configuration of a carrier wave generation unit according to a modification of the first embodiment.
• 19 12 is a block diagram illustrating an example of a hardware configuration that implements functions of the inverter control device according to the first embodiment.
• 20 12 is a block diagram illustrating another example of the hardware configuration that implements the functions of the inverter control device according to the first embodiment.
• 21 12 is a diagram illustrating an exemplary configuration of a carrier wave generation unit according to a second embodiment.
• 22 12 is a diagram illustrating an exemplary configuration of a carrier wave generation unit according to a third embodiment.
• 23 Figure 12 is a diagram showing a detailed configuration of a frequency modulation unit used in 22 is illustrated.
• 24 FIG. 12 is a diagram showing an output image of a frequency modulation amount output from FIG 23 illustrated frequency modulation unit illustrated.

Description of the embodiments

Hereinafter, an inverter control device and an electric motor drive device according to embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that although an electric motor driving device applied to a railroad system will be described as an example in the following embodiments, it is not intended to exclude applications for other uses.

First embodiment.

1 12 is a diagram illustrating an example configuration of an electric motor drive device 1 including an inverter control device 5 according to a first embodiment. As in 1 1, the electric motor drive device 1 according to the first embodiment includes a filter capacitor 3, an inverter 4, and the inverter control device 5. The inverter 4 is connected to an electric motor 105. FIG. The electric motor 105 is a three-phase electric motor mounted on an electric vehicle.

A DC power fed from a trolley wire 101 is supplied to the electric motor driving device 1 via a current collector 102 and a filter reactor (coil) 2 . Beyond the trolley wire 101 there is a substation (not illustrated), and the trolley wire 101 serves as an external power supply for the electric motor drive device 1 . It is noted that a trolley line voltage, which is a voltage of the trolley line 101, is applied to the pantograph 102, and each conversion capacity of the inverter 4 differs depending on a drive system. The catenary voltage ranges from about 600 to 3000 [V]. Furthermore, the conversion capacities range from a few tens to a few hundred kilovolt-amperes [kVA].

The positive-side terminal P of the electric motor drive device 1 is connected to the filter reactor 2 . The negative-side terminal N of the electric motor driving device 1 is connected to a rail 104 via a wheel 103 . As a result, due to the DC power fed from the trolley wire 101, a direct current flows through the filter reactor 2, the electric motor drive device 1, the electric motor 105, the wheel 103 and the rail 104, and then returns to the substation.

It is noted that although in 1 an overhead electric line is illustrated as the overhead line 101 and a pantograph pantograph is illustrated as the pantograph 102, the present disclosure is not limited thereto. As the trolley line 101, a third rail used for subways or the like could be used, and accordingly, a pantograph suitable for a third rail could be used as the pantograph 102. Furthermore, the catenary 101 could be an AC catenary, although in 1 a case where the trolley line 101 is a DC trolley line is illustrated. It is noted that in a case where the trolley line 101 is an AC trolley line, a transformer that steps down the received AC voltage is provided instead of the filter reactor 2, and a converter that converts the AC voltage output from the transformer into a Converting DC voltage is provided in a subsequent stage of the transformer.

Furthermore, the present disclosure, although in 1 the filter reactor 2 is illustrated as a component external to the electric motor drive device 1, not limited thereto. The filter choke 2 could be provided in the electric motor drive device 1 .

The filter capacitor 3 is connected between the positive-side terminal P and the negative-side terminal N inside the electric motor drive device 1 . As a result, the filter capacitor 3 on the input side of the inverter 4 is connected to both ends of the inverter 4 in parallel.

The filter capacitor 3 smoothes the applied DC voltage. Furthermore, the filter capacitor 3 is connected to the filter choke 2 and configures an LC filter circuit together with the filter choke 2 . This LC filter circuit reduces a surge voltage applied from the trolley line 101 side. Furthermore, the LC filter circuit reduces the magnitude of a ripple component of the current flowing in the inverter 4 . The inverter 4 is a power conversion circuit that supplies power to the electric motor 105 .

An operation of the inverter 4 is controlled by the inverter control device 5 . The inverter 4 converts the DC voltage of the filter capacitor 3 into an AC voltage having a given voltage value and a given frequency, and applies the AC voltage to the electric motor 105 .

The inverter control device 5 includes a voltage command calculation unit 6 , a PWM control unit 7 , and a carrier wave generation unit 8 . Information on a torque command and information on an electric motor frequency are input to the inverter control device 5 . The voltage command calculation unit 6 calculates a voltage command based on the torque command and the electric motor frequency. The carrier wave generation unit 8 generates a carrier wave based on the electric motor frequency. The PWM controller 7 generates a PWM control signal used to control a switching element of the inverter 4 based on the voltage command and the carrier wave, and outputs the PWM control signal to the inverter 4 . The PWM control signal is generated by making an amplitude comparison between the voltage command and the carrier wave. A method of generating the PWM control signal will be described later.

2 FIG. 12 is a diagram illustrating an example configuration of the general inverter main circuit. The inverter main circuit includes upper arm semiconductor elements UPI, VPI and WPI and lower arm semiconductor elements UNI, VNI and WNI.

The semiconductor elements UPI and UNI are connected in series so as to form a U-phase leg. The semiconductor elements VPI and VNI are connected in series so as to form a V-phase leg. The semiconductor elements WPI and WNI are connected in series so as to form a W-phase leg. The U-phase leg, the V-phase leg and the W-phase leg are connected in parallel to establish a three-phase bridge circuit.

3 represents a diagram showing an equivalent circuit in 1 illustrates which is used to explain a leakage current. In 3 the electric motor 105 is represented by circuit symbols of an inductor. Regardless of the type of the electric motor, in a case where a three-phase motor is driven by a three-phase inverter, a neutral point potential of the three-phase motor fluctuates. Therefore, as in 3 1, the equivalent circuit is formed in which a stray capacitor 34 is connected between a neutral point potential 32 of the electric motor 105 and a reference potential 31 which is the ground potential. The neutral point potential 32 includes a high frequency component caused by PWM control. Therefore, when a U-phase voltage 33U, a V-phase voltage 33V, and a W-phase voltage 33W are applied to the electric motor 105, a leakage current 35 flows through the stray capacitor 34.

It is noted that the potential difference between the neutral point potential 32 and the reference potential 31 is referred to as a "common mode voltage". In a case of the three-phase inverter, the common mode voltage is calculated by (Vu+Vv+Vw)/3, where Vu indicates U-phase voltage 33U, Vv indicates V-phase voltage 33V, and Vw indicates W-phase voltage 33W.

4 Fig. 12 is a diagram used to explain the method of generating PWM control signals provided to the semiconductor elements of each arm shown in Fig 2 is illustrated. In 4 Illustrated are a U-phase voltage command 26U, a V-phase voltage command 26V, and a W-phase voltage command 26W representing sine waves, and a carrier wave 28 representing a triangle wave. The horizontal axis represents the phase angle and the vertical axis represents the amplitude value. A value 1 [Vpu] on the vertical axis is equivalent to half the amplitude of the voltage applied to the inverter 4, in other words, half the DC voltage which is a voltage of the filter capacitor 3.

5 represents a diagram illustrating PWM control signals generated by the in 4 illustrated individual phase voltage commands. 5 12 illustrates a U-phase PWM control signal, a V-phase PWM control signal, and a W-phase PWM control signal in this order from above. The horizontal axis in 5 represents the phase angle as in 4 . In 5 Illustrated are waveforms of the PWM control signals when the modulation rate is 0.8. In this description, the modulation rate is defined as a ratio between a half of the DC voltage applied to the inverter 4 and the amplitude of an AC phase voltage applied to the electric motor 105 through the inverter 4 . It should be noted that the definition here is exemplary and that the modulation rate could be defined in any way.

The PWM controller 7 compares the U-phase voltage command 26U and the carrier wave 28 which is a triangular wave signal. When the U-phase voltage command 26U is greater than the carrier wave 28, the U-phase PWM control signal becomes "ON", and when the U-phase voltage command 26U is less than or equal to the carrier wave 28, the U-phase PWM -Control signal to "OFF". In this way, the U-phase PWM control signal generated that in the upper part of the 5 is illustrated. Similarly to the U-phase PWM control signal, the V-phase PWM control signal and the W-phase PWM control signal are generated by comparing the V-phase voltage command 26V and the W-phase voltage command 26W with the carrier wave 28, respectively. The V-phase PWM control signal and the W-phase PWM control signal generated at this time are respectively in the middle part and the lower part of the 5 illustrated.

6 represents a diagram illustrating a common-mode voltage represented by the in 5 illustrated PWM control signals is generated. In 6 the horizontal axis represents the phase angle and the vertical axis represents the amplitude of the common mode voltage. As in 6 1, when the modulation rate is relatively large, a common mode voltage has a waveform that changes stepwise between steps of ±1 [Vpu] or ±1/3 [Vpu].

Leakage current flows every time the common mode voltage changes. Furthermore, since the change amount (voltage change rate) of the common mode voltage per unit time increases, the amplitude of the leakage current increases. Therefore, in order to reduce the leakage current 35 flowing through the stray capacitor 34, a reduction in the rate of change of a common mode is important.

7 represents a diagram illustrating an example of each phase voltage command with the modulation rate different from that in 4 differs. In 7 each phase voltage command is illustrated when the modulation rate is 0.1. A distinction between a solid line, a broken line and a long-short dashed line is the same as that in 4 . That is, the solid line indicates the U-phase voltage command 26U, the broken line indicates the V-phase voltage command 26V, and the long-short dashed line indicates the W-phase voltage command 26W.

8th FIG. 12 is a diagram illustrating PWM control signals generated by the individual phase voltage commands shown in FIG 7 are illustrated. In 8th Illustrated are waveforms of the PWM control signals when the modulation rate is 0.1. The order of the PWM control signals is the same as those in 5 , and the U-phase PWM control signal, the V-phase PWM control signal, and the W-phase PWM control signal are illustrated in this order from above.

When the modulation rate takes a value close to zero, as in 8th 1, the difference between the PWM control signals in the respective phases decreases and the output of the inverter 4 is in almost a zero voltage vector state. Here, the state of zero voltage vector means a state in which all of the upper-side arm members are turned on or all of the lower-side arm members are turned on.

9 represents a diagram illustrating a common-mode voltage represented by the in 8th illustrated PWM control signals is generated. As in 9 As illustrated, when the modulation rate is near zero, a common-mode voltage has a waveform that sweeps back and forth between steps of ±1 [Vpu] in the shortest possible time. Therefore, the voltage change rate increases compared to a case where the modulation rate is 0.8, which is relatively large, and the leakage current 35 flowing through the stray capacitor 34 increases.

10 12 is a diagram illustrating an example of waveforms in a case where the carrier wave phases of the respective phases are shifted by 120° in the carrier wave and each phase voltage command shown in 7 are illustrated. in the in 10 In the illustrated example, the phase of the V-phase carrier wave 28V indicated by a broken line is delayed by 120° with respect to the phase of a U-phase carrier wave 28U indicated by a solid line. Furthermore, the phase of a W-phase carrier wave 28W indicated by a long-short dashed line advances by 120° with respect to the U-phase carrier wave 28U. It is noted that advancing the phase by 120° is equivalent to retarding the phase by 240°.

11 FIG. 12 is a diagram illustrating PWM control signals generated by the individual phase voltage commands and the individual phase carrier waves shown in FIG 10 are illustrated. In the 11 The illustrated waveforms indicate that on or off timings of the PWM control signals of the respective phases are different from each other. Therefore, in a case where the carrier wave phases of the respective phases are shifted by 120° from each other, it is understandable that even in a case where the modulation rate takes a value close to zero, the zero voltage vector is not equal to 8th is not evoked.

12 Figure 12 is a diagram illustrating an example of a common mode voltage waveform represented by the in 11 illustrated PWM control signals is generated. According to 12 exhibits itself in a case where the modulation rate is close to zero, the common mode voltage exhibits a waveform that goes back and forth between steps of ±1/3 [Vpu]. Therefore, the voltage change rate compared to example in 9 smaller in which the carrier wave phase of each phase is the same. Therefore, the leakage current 35 flowing through the stray capacitor 34 decreases.

13 12 is a diagram illustrating an example of a harmonic distribution of an electric motor current according to a conventional control when the carrier waves of the respective phases are the same. In 13 the vertical axis represents the current amplitude. Control parameters of a waveform in 13 include a carrier wave frequency of 800 Hz, a drive frequency of 20 Hz and a modulation rate of 0.2. According to 13 a 20 Hz component of the drive frequency appears large, and a 2f component (1600 Hz) of the carrier wave frequency appears although its amplitude is relatively small.

14 12 is a diagram illustrating an example of the harmonic distribution of the electric motor current according to the conventional control in a case where the carrier wave phases of the respective phases are shifted from each other by 120°. It is noted that control parameters other than the carrier wave phase are the same as those in the example of FIG 13 are. 14 shows that a 1f component (800 Hz) of the carrier wave frequency increases significantly. As can be understood from this result, in a case where the carrier wave phases of the respective phases are shifted by 120° from each other, this causes a problem that electromagnetic noise emitted from the electric motor increases.

In 12 it has been described that in a case where the carrier wave phases of the respective phases are shifted by 120° from each other, the leakage current 35 flowing through the stray capacitor 34 is reduced. However, the disclosure of the present application has found that in a case where the carrier wave phases of the respective phases are shifted by 120° from each other, when a value of the modulation rate is relatively large, an effect of reducing the leakage current 35 flowing through the stray capacitor is reduced 34 flows. This point will be described below.

15 12 is a diagram showing an example of the common mode voltage waveform according to the conventional control in a case where the carrier wave phases of the respective phases are shifted by 120° from each other. Control parameters that differ from the carrier wave phase in the waveform of the 15 include a carrier wave frequency of 800 Hz, a drive frequency of 20 Hz, and a modulation rate of 0.8. According to 15 it is understandable that even in a state where the carrier wave phases are shifted by 120°, when the modulation rate increases, the common mode voltage waveform changes to the level of ±1 [Vpu], and thus the effect of reducing the leakage current 35 is reduced.

16 FIG. 12 is a diagram used to explain a concept of a control method according to the first embodiment. The horizontal axis represents modulation rate and the vertical axis represents noise level. As the speed of the electric motor is greater, the modulation rate is greater. Therefore the modulation rate in the horizontal axis could be read as the speed of the electric motor. The noise level in the vertical axis means a noise level caused by the leakage current 35. FIG. The thick solid line K1 represents a noise level in a case where there is a carrier wave phase difference, that is, where there is a phase difference between the carrier wave phases of the respective phases. A thick broken line K2 represents a noise level in a case where there is no carrier wave phase difference, that is, in a case where there is no phase difference between the carrier wave phases of the respective phases. Furthermore, a thin broken line K3 drawn parallel to the horizontal axis represents the threshold of the noise level. It is noted that the threshold is a value that changes according to a car type and a route of an electric vehicle.

16 shows that in a case where there is no carrier wave phase difference, a noise level caused by the leakage current 35 is lowered as the modulation rate increases. On the other hand, the 16 also that in a case where there is a carrier wave phase difference, the noise level caused by the leakage current 35 increases as the modulation rate increases. Therefore, in a range where the limit of the noise level can be satisfied without a carrier wave phase difference, it can be said that it is desirable to select a conventional modulation method with no carrier wave phase difference from the viewpoint of noise.

Based on the above-described matters, the carrier wave generation unit 8 in the inverter control device 5 according to the first embodiment is as in FIG 17 furnished. 17 12 is a diagram showing an exemplary configuration of the carrier wave generation unit 8 according to the first embodiment. As in 17 1, according to the first embodiment, the carrier wave generation unit 8 comprises a phase calculation unit 81 and a carrier wave output unit 82.

The phase calculation unit 81 includes an integrator 811, a phase difference calculation unit 812, a subtractor 813, and an adder 814. The integrator 811 calculates a first carrier wave phase θ _cu based on a carrier wave frequency command f _c . The phase difference calculation unit 812 calculates a phase difference Δθ _c based on the electric motor frequency. The subtracter 813 calculates a second carrier wave phase θ _cv by subtracting the phase difference Δθ _c from the first carrier wave phase θ _cu . The adder 814 calculates a third carrier wave phase θ _cw by adding the phase difference Δθ _c to the first carrier wave phase θ _cu . It is noted that in 17 an input signal of the phase difference calculation unit 812 is adopted as the electric motor frequency. However, the present disclosure is not limited to this. Modulation rate or speed information about the electric vehicle could be used instead of electric motor frequency. Furthermore, the phase difference calculation unit 812 may have a configuration that outputs the phase difference Δθ _c according to a reference table or a configuration that outputs the phase difference Δθ _c by a function calculation.

When processing in 17 the phase difference Δθ _c means a shift width of the carrier wave phase. As referred to 16 described, the shift width of the carrier wave phase between the respective phases causes a problem of noise related to the modulation rate. Therefore, it is desirable to set the carrier wave phase shift width to the necessary minimum. Furthermore, a configuration can be considered in which an operation mode is provided and the shift width of the carrier wave phase is controlled by switching the operation mode. However, there is a concern that the configuration that switches the operation mode causes torque shock. Therefore, in the first embodiment, a configuration is used in which the shift width of the carrier wave phase changes continuously, and a configuration is used in which the shift width of the carrier wave phase decreases stepwise as the electric motor frequency increases.

The first carrier wave phase θ _cu , the second carrier wave phase θ _cv , and the third carrier wave phase Q _cw calculated by the phase calculation unit 81 are input to the carrier wave output unit 82 . The carrier wave output unit 82 generates a U-phase carrier wave c _u using the first carrier wave phase θ _eu and outputs the U-phase carrier wave c _u . The carrier wave output unit 82 generates a V-phase carrier wave c _v using the second carrier wave phase θ _cv and outputs the V-phase carrier wave c _v . The carrier wave output unit 82 generates a W-phase carrier wave c _w using the third carrier wave phase θ _cw and outputs the W-phase carrier wave c _w .

As described above, the phase calculation unit 81 calculates the first carrier wave phase θ _cu , the second carrier wave phase θ _cv , and the third carrier wave phase θ _cw based on the carrier wave frequency command f _c and the electric motor frequency. Furthermore, the carrier wave output unit 82 outputs the U-phase carrier wave c _u , the V-phase carrier wave c _v and the W-phase carrier wave c _w , which are three-phase carrier waves, based on the first carrier wave phase θ _cu , the second carrier wave phase θ _cv and the third carrier wave phase θ _{c w} . According to the carrier wave generation unit 8 configured in this way, both common mode noise reduction in a low speed range and noise reduction in a middle to high speed range can be achieved. Furthermore, control that does not cause a shock at a mode transition can be achieved.

It is noted that in 17 the configuration is such that the phase difference between the first carrier wave phase θ _cu and the second carrier wave phase θ _cv is equal to the phase difference between the first carrier wave phase θ _cu and the third carrier wave phase θ _cw . However, these phase differences could differ. What is important is that the first carrier wave phase θ _cu , the second carrier wave phase θ _cv and the third carrier wave phase θ _cw have phase differences from each other, and that the phase difference changes according to the change in electric motor frequency. If this point is secured, an effect of the first embodiment described herein can be obtained.

Furthermore, the carrier wave generation unit 8, which is 17 illustrated, be set up as shown in 18 is illustrated. 18 12 is a diagram illustrating an exemplary configuration of a carrier wave generation unit 8A according to a modification of the first embodiment. in the in 18 Illustrated carrier wave generation unit 8A is the phase calculation unit 81 in the configuration of the carrier wave generation unit 8 shown in FIG 17 is replaced by a phase calculation unit 81A. In the phase calculation unit 81A, integrators 815 and 816 are added to the configuration of the phase calculation unit 81 shown in FIG 17 is illustrated. Other components are equivalent to the components of the phase calculation unit 81 shown in 17 is illustrated, and the equivalent components will be denoted by the same reference numerals and overlapping description will be omitted.

In 18 A configuration is used in which the input carrier wave frequency command f _c is branched into three carrier wave frequency commands of the respective phases, i.e., a U-phase carrier wave frequency command f _cu , a V-phase carrier wave frequency command f _cv , and a W-phase carrier wave frequency command f _cw , in the phase calculation unit 81A and input to individual integrators provided for the respective phases. Since signals input to the respective integrators 811, 815 and 816 are the same, operation becomes equivalent to 17 carried out.

As described above, the inverter control device according to the first embodiment includes the carrier wave generation unit that generates the three-phase carrier waves, and the carrier wave generation unit calculates the first to third carrier wave phases based on the carrier wave frequency command and the electric motor frequency. The first to third carrier wave phases have the phase differences from each other, and the phase difference changes continuously according to the change in the electric motor frequency. As a result, the common mode voltage generated by the PWM control signals can be reduced. As a result, the leakage current that might flow through the stray capacitor can be reduced; therefore, it is possible to reduce leakage noise without additionally providing a filter component.

It is noted that it is desirable that the second and third carrier wave phases have the phase differences with respect to the first carrier wave phase that are equal in magnitude but opposite in sign. In this way, the effect of reducing common mode noise can be enhanced.

Furthermore, when the electric motor frequency is zero, it is desirable that the phase difference between the first to third carrier wave phases is 120°. In this way, the effect of reducing the common mode noise can be further enhanced.

Next, a hardware configuration for implementing functions of the inverter control device 5 according to the first embodiment will be explained with reference to the drawings in FIGS 19 and 20 to be discribed. 19 12 is a block diagram illustrating an example of the hardware configuration that implements the functions of the inverter control device 5 according to the first embodiment. 20 12 is a block diagram illustrating another example of the hardware configuration that implements the functions of the inverter control device 5 according to the first embodiment.

In a case where some or all of the functions of the inverter control device 5 according to the first embodiment are implemented as in FIG 20 As illustrated, a configuration including a processor 200 that performs calculations, a memory 202 that stores a program read by the processor 200, and an interface 204 that inputs and outputs signals can be used.

Processor 200 could be a computing device, such as a computing device, microprocessor, microcomputer, central processing unit (CPU), or digital signal processor (DSP). Furthermore, memory 202 could be, for example, non-volatile or volatile semiconductor memory, such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), or electronic EPROM (EEPROM) (registered trademark), a magnetic disk, a floppy disk, an optical disk, a compact disk, a mini disk or a DVD.

The memory 202 stores a program that executes the functions of the inverter control device 5 according to the first embodiment. The processor 200 can perform the above processing by receiving required information via the interface 204, executing the program stored in the memory 202 by the processor 200, and referring to a table stored in the memory 202 by the processor 200 is taken. A calculation result of the processor 200 can be stored in the memory 202 .

Furthermore, in a case where some of the functions of the inverter control device 5 are implemented according to the first embodiment, a processing circuit 203 can be used, which is shown in FIG 24 is illustrated. The processing circuitry 203 corresponds to a single circuit, a compound circuit, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a combination thereof. Information input to the processing circuit 203 and information output from the processing circuit 203 can be obtained via the interface 204 .

It is noted that part of the processing of the inverter control device 5 may be performed by the processing circuit 203 , and processing that is not performed by the processing circuit 203 may be performed by the processor 200 and memory 202 .

Second embodiment.

21 12 is a diagram illustrating an exemplary configuration of a carrier wave generation unit 8B according to a second embodiment. In the carrier wave generation unit 8B shown in FIG 21 1, a frequency modulation unit 83 and an adder 84 are provided in a stage preceding the phase calculation unit 81 in the configuration of the carrier wave generation unit 8 shown in FIG 17 is illustrated. The frequency modulation unit 83 is provided to reduce noise.

The frequency modulation unit 83 includes a random number generator 831 and an amplifier 832. The adder 84 has a configuration to which a basic carrier wave frequency command f _c0 and an output of the frequency modulation unit 83 are input. Other components are equivalent to the components of the phase calculation unit 81 shown in 17 is illustrated, and the equivalent components are denoted by the same reference numerals, and overlapping description will be omitted.

In 21 in the frequency modulation unit 83, the amplifier 832 amplifies an output of the random number generator 831. An output of the amplifier 832 is input to the adder 84 as a frequency modulation amount Δf _c . The frequency modulation unit 83 is a configuration unit that performs so-called random modulation and that calculates the frequency modulation amount Δf _c based on the output of the random number generator 831 . The adder 84 adds the carrier wave frequency command f _c and the frequency modulation amount Δf _c and outputs the addition result to the phase calculation unit 81 as a new carrier wave frequency command f _c1 .

According to the carrier wave generation unit 8B disclosed in FIG 21 As illustrated, the frequency modulation amount Δf _c is generated based on a random number generated by the random number generator 831 . Then, the generated frequency modulation amount Δf _c is added to the carrier wave frequency command f _c common to each phase. Therefore, even in a case where the phase difference between the respective carrier waves is provided, all the carrier waves are frequency-modulated based on a random number generated from only a seed. As a result, while the carrier wave of each phase is frequency-modulated, a state is maintained where the waveforms maintain a phase difference therebetween. Therefore, it is possible to prevent the effect of reducing the common mode noise from deteriorating.

As described above, according to the inverter control device according to the second embodiment, the carrier wave generation unit calculates the frequency modulation amount based on the output of the random number generator and adds the calculated frequency modulation amount to all carrier wave frequency commands to be input to the phase calculation unit. As a result, it is possible to reduce noise while preventing the effect of reducing common mode noise from deteriorating

Third embodiment.

22 12 is a diagram illustrating an exemplary configuration of a carrier wave generation unit 8C according to a third embodiment. In the carrier wave generation unit 8C shown in FIG 22 1, a frequency modulation unit 85 is in a stage preceding the phase calculation unit 81A in the configuration of the carrier wave generation unit 8A shown in FIG 18 is provided and the phase calculation unit 81A in the configuration of the carrier wave generation unit 8A shown in FIG 18 illustrated is replaced by a phase calculation unit 81B. in the in 22 In the phase calculation unit 81B illustrated in FIG 18 is illustrated. The frequency modulation unit 85 is provided to reduce noise more effectively than the Fre to reduce frequency modulation unit 83 according to the second embodiment shown in 21 is illustrated. Other components are equivalent to the components of the carrier wave generation unit 8A shown in FIG 18 is illustrated, with the equivalent components being denoted by the same reference numerals and overlapping description will be omitted.

23 12 is a diagram showing a detailed configuration of the frequency modulation unit 85 shown in FIG 22 is illustrated. The frequency modulation unit 85 includes a list 851, an order control unit 852, and switching units 853a, 853b, and 853c. In the list 851, frequency values of a plurality of numbers of pieces of data are stored. More specifically, the list 851 stores frequency values f _i ( _{f_0} , _{f_1} ,..., and f_n) of _n +1 points that have a value greater than or equal to -f _L and less than or equal to +f _H and which are optionally selected. The number n+1 is the number of data pieces. Reference characters n, f _L and f _H indicate preset setting values. Preferably, f _L =f _H . Furthermore, it is desirable that the frequency values f _i of the n+1 points are at equal intervals, that is, all differences between adjacent frequency values f _i are all equal to each other when the frequency values f _i are arranged in an ascending or descending order . Furthermore shows 23 that n, f _L and f _H are applied from outside the frequency modulation unit 85. However, a configuration in which n, f _L and f _H are set in the frequency modulation unit 85 can be used.

The sequence control unit 852 controls the switching units 853a, 853b and 853c and randomly selects an item from items stored in the list 851 without overlapping so as to select the selected items as a first frequency modulation amount Δf _cu , a second frequency modulation amount Δf _cv and to output a third frequency modulation amount Δf _cw . Furthermore, after all items in the list 851 have been selected, the items in the list are selected in a random order different from the previous order, and this selection processing is repeated.

The frequency modulation unit 85 outputs the selected items one by one in a first random order without an overlap with the items stored in the list 851 as the first frequency modulation amount Δf _cu , and the first frequency modulation amount Δf _cu is input into the adder 817a entered. Furthermore, the frequency modulation unit 85 outputs the selected items one by one in a second random order without an overlap with the items stored in the list 851 as the second frequency modulation amount Δf _cv , and the second frequency modulation amount Δf _cv is converted into the adder 817b input. Furthermore, the frequency modulation unit 85 outputs the selected items one by one in a third random order without an overlap with the items stored in the list 851 as the third frequency modulation amount Δf _cw , and the third frequency modulation amount Δf _cw is converted into the adder 817c input.

In 22 the adder 817a adds the carrier wave frequency command f _c and the first frequency modulation amount Δf _cu , and the addition result is input to the integrator 811 as the U-phase carrier wave frequency command f _cu . The adder 817b adds the carrier wave frequency command f _c and the second frequency modulation amount Δf _cv , and the addition result is input to the integrator 815 as the V-phase carrier wave frequency command fcv. The adder 817c adds the carrier wave frequency command f _c and the third frequency modulation amount Δf _cw , and the addition result is input to the integrator 816 as the W-phase carrier wave frequency command f _cw . The subsequent operation is as described above, and description will be omitted here.

24 FIG. 12 is a diagram illustrating an output image of the frequency modulation amount Δf _c obtained from the FIG 23 illustrated frequency modulation unit 85 is output. The frequency modulation amount Δf _c represents any one of the first frequency modulation amount Δf _cu , the second frequency modulation amount Δf _cv , and the third frequency modulation amount Δf _cw . In the upper part of the 24 the frequency modulation amount Δf _c output from the frequency modulation unit 85 is expressed as a sequence {f _xi }={f _x0 ,f _x1 ,f _x2 ,...,f _xn } (i=0,1,2,.. .,n) represented. Furthermore, in the lower part of the 24 illustrates a time when each element of the sequence {f _xi } is output. An output time of each element could be reformulated as a time taken to switch the output. According to 24 an output time of element f _xi is a reciprocal of element f _xi . That is, a time from when an i-th item is selected until the i-th item is switched to an i+1-th item is set as a reciprocal of the i-th item. Assuming that a time from when a first item is output until a final item is output is T _cyc , the time T _cyc in the list 851 can be expressed by the following formula (1).
[Formula 1] $$T_{cyc}={\displaystyle {\sum }_{i=0}^{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="DE112020006657T5\_0002.png,DE112020006657T5\_0005.png"\; state="\{\{state\}\}">n</figure-callout>}}\frac{1}{{ƒ}_{xi}}}$$

Although the frequency modulation amount Δf _c of each phase differs, only the order of selection of the items from the list 851 differs. Therefore, even if the items stored in the list 851 are selected in any order, the time is T _cyc always the same, which is needed until all items in the list 851 are selected. This means that although the carrier wave frequencies of the respective phases are modulated with different random numbers, the carrier wave phase difference is returned to the adjusted value every time T _cyc . Therefore, by using the frequency modulation unit 85 according to the third embodiment, it is possible to achieve both the reduction in common mode noise and improvement in listening feeling. In particular, since the number of pieces of data n+1 is smaller and a value range of the frequency value stored in the list 851 is narrower, the effect of reducing the common mode noise is prioritized. Conversely, when the number of pieces of data n+1 is larger and the value range of the frequency values stored in the list 851 is wider, the improvement of the hearing feeling is prioritized.

As described above, according to the inverter control device according to the third embodiment, the carrier wave generation unit includes the frequency modulation unit that outputs the first frequency modulation amount Δf _cu , the second frequency modulation amount Δf _cv , and the third frequency modulation amount Δf _cw . The first frequency modulation amount Δf _cu is an item selected one by one in the first random order without overlapping with items stored in a first phase list. Furthermore, the second frequency modulation amount Δf _cv is an item selected one by one in the second random order without overlapping with items stored in a second phase list. The third frequency modulation amount Δf _cw is an item selected one by one in the third random order without overlapping with items stored in a third phase list. The first frequency modulation amount Δf _cu , the second frequency modulation amount Δf _cv , and the third frequency modulation amount Δf _cw are added on a one-to-one basis to the carrier wave frequency command. Furthermore, when the first frequency modulation amount Δf _cu , the second frequency modulation amount Δf _cv , and the third frequency modulation amount Δf _cw are selected from the lists of the respective phases and output, is the time from which the ith item is selected to the ith item is switched to the i+1th element, the reciprocal of the ith element. This makes it possible to achieve both the reduction in common mode noise and the improvement in hearing feeling.

It is noted that the number of items in the list of each phase could be changed according to the motor frequency. Furthermore, if a minimum value of the items stored in the list of each phase is set as a first value and a maximum value is set as a second value, the first value and/or the second value could be changed according to the electric motor frequency . By changing the number of data pieces of the first value or the second value according to the electric motor frequency, it is possible to perform control according to a priority between the effect of reducing the common mode noise and improving the hearing feeling.

Furthermore, it is desirable that the first value and the second value in the list of each phase have the same absolute values but different signs, and that the respective elements in the list have equidistant values. With this setting, without changing a total amount of a switching loss caused by the inverter 4, it is possible to perform the control according to the priority between the reduction of the common mode noise and the improvement of the hearing feeling.

The configurations given in the above embodiments are examples and can be combined with other known technology, and the embodiments can be combined with each other, and the configurations given in the embodiments can be partially omitted or changed , without deviating from the scope.

For example, the inverter control device has been described as the device included in the electric motor drive device. However, the inverter control device is not limited to this. It is sufficient that the inverter control device is electrically connected to the inverter, and the inverter control device may be configured as a device external to the electric motor drive device.

reference list

1

electric motor drive device;

2

filter choke(coil);

3

filter capacitor;

4

inverter;

5

inverter control device;

6

voltage command calculation unit;

7

PWM control unit;

8, 8A, 8B, 8C

carrier wave generation unit;

26U

U phase voltage command;

26V

V phase voltage command;

26W

W phase voltage command;

28

carrier wave;

28U

U-phase carrier wave;

28V

V-phase carrier wave;

28W

W-phase carrier wave;

31

reference potential;

32

neutral point potential;

33U

U phase voltage;

33V

V phase voltage;

33W

W phase voltage;

34

stray capacitor;

35

leakage current;

82

carrier wave output unit;

81, 81A, 81B

phase calculation unit;

83, 85

frequency modulation unit;

84, 814, 817a, 817b, 817c

adder;

101

catenary;

102

pantograph;

103

Wheel;

104

Rail;

105

electric motor;

200

Processor;

202

Storage;

203

processing circuit;

204

Interface;

811, 815, 816

integrator;

812

phase difference calculation unit;

813

subtractor;

831

random number generator;

832

Amplifier;

851

List;

852

sequence control unit;

853a, 853b, 853c

switching unit;

N

negative side connection;

P

positive side connection;

UNI, UPI, VNI, VPI, WNI, WPI

semiconductor element.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP2004187368 [0003]

Claims (9)

An inverter control device that controls an inverter that drives a three-phase electric motor by pulse width modulation, the inverter control device comprising: a carrier wave generating unit for generating three-phase carrier waves; and a pulse width modulation controller for controlling a switching state of the inverter by comparing the carrier wave with a modulated wave, wherein comprises the carrier wave generation unit a phase calculation unit for calculating first to third carrier wave phases based on a carrier wave frequency command and an electric motor frequency, and a carrier wave output unit for outputting the three-phase carrier waves based on the first to third carrier wave phases, the first to third carrier wave phases have phase differences from each other, and the phase difference changes continuously in accordance with a change in the electric motor frequency. Inverter control device according to claim 1 , wherein the second and third carrier wave phases have phase differences with respect to the first carrier wave phase that are equal in magnitude but opposite in sign. Inverter control device according to claim 2 , where the phase difference when the electric motor frequency is zero is 120°. Inverter control device according to one of Claims 1 until 3 wherein the carrier wave generation unit comprises a frequency modulation unit for calculating a frequency modulation amount based on an output of a random number generator and adding the frequency modulation amount to all carrier wave frequency commands to be input to the phase calculation unit. Inverter control device according to one of Claims 1 until 3 , wherein the carrier wave generation unit comprises a frequency modulation unit for calculating first to third frequency modulation amounts, the frequency modulation unit comprises a list for storing frequency values of a plurality of numbers of pieces of data, each item stored in the list having a value greater than or equal to one first value and which is less than or equal to a second value, an item selected one by one in a first random order without overlapping from the items stored in the list when outputting the first frequency modulation amount Item selected one by one in a second random order without an overlap against the items stored in the list when outputting the second frequency modulation amount, one item selected one by one in a third random order without an overlap is selected against the items stored in the list when the third frequency modulation amount is output when the number of data pieces is set as n+1 and i is set as an integer greater than or equal to one and less than or equal to n, a time from when an i-th element is selected until an i-th element is switched to an i+1-th element is a reciprocal of the i-th element, and the first to third frequency modulation amounts on a one-to-one One base added to the carrier wave frequency command. Inverter control device according to claim 5 , wherein the number of pieces of data in the list is changed in accordance with the electric motor frequency. Inverter control device according to claim 5 or 6 , wherein the first value and/or the second value is changed in accordance with the electric motor frequency. Inverter control device according to one of Claims 5 until 7 , where the first and second values in the list have equal absolute values but different signs, and respective elements in the list have equal values at equal distances. An electric motor driving device comprising: the inverter control device according to any one of Claims 1 until 8th ; and an inverter controlled by the inverter control device.

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