Power Conversion Equipment

Abstract

In a power conversion device that converts a DC voltage to an AC voltage by turning a semiconductor switching element (Q) on and off, a drive controller (10) that generates a gate signal for driving the semiconductor switching element (Q) on and off is configured to generate a first command which is a voltage command for a target voltage of the AC voltage, generate a triangular wave carrier signal whose frequency is an even multiple of a fundamental wave component of the first command, and generate the gate signal from the carrier signal and a second command composed of a harmonic signal including at least one odd-multiple harmonic signal whose frequency is an odd-multiple and one even-multiple harmonic signal whose frequency is an even multiple of the fundamental wave component of the first command, and the first command.

Description

[Technical field]

[0001] The present disclosure relates to a power conversion device. [Background technology]

[0002] Inverters are widely used as power conversion devices that convert DC power to AC power. Inverters apply a desired AC voltage to a load, such as a rotating machine, by comparing a sinusoidal modulating signal with a triangular carrier signal and using pulse width modulation (PWM) through the switching operation of semiconductor switching elements. (Hereinafter, PWM based on the result of comparison with a triangular carrier is referred to as triangular wave comparison type PWM.) However, because PWM causes harmonics to be contained in the voltage applied to the load, harmonics are also generated in the current flowing through the load. These harmonics cause noise or increased losses in the load, and in the case of a rotating machine, they cause not only increased noise or losses but also torque pulsation and vibration, so it is desirable to suppress the harmonics generated by PWM.

[0003] As a method for suppressing harmonics, there is a method called low-order harmonic elimination PWM or optimal pulse pattern, which designs the switching phase so as to suppress harmonic components of a specified order relative to the fundamental frequency of the load (for example, Patent Document 1). However, these methods cannot be implemented in a general-purpose controller IC because they require issuing a command to perform switching operation at a specified phase.

[0004] Therefore, an implementation method has been disclosed that can obtain effects equivalent to low-order harmonic removal PWM or optimal pulse patterns by using a triangular wave comparison type PWM mounted on a general-purpose controller IC (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-215041 A [Patent Document 2] JP 2020-171086 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the power conversion device of Patent Document 2, a PWM command is generated by comparing a triangular wave with a DC modulation signal that has a positive and negative symmetrical shape in one electrical angle cycle, so the number of PWM pulses (the number of on or off switching operations) in one electrical angle cycle is always odd. Therefore, when the number of pulses is even, there is a problem that the effect of suppressing harmonics cannot be obtained.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to control load noise and losses with a simple configuration even when the number of pulses is an even number, and to control the noise, torque pulsation, vibration, and losses of the rotating machine when the load is a rotating machine. [Means for solving the problem]

[0008] The power conversion device disclosed herein is a power conversion device that converts a DC voltage into an AC voltage by turning a semiconductor switching element on and off, and a drive controller that generates a gate signal for driving the semiconductor switching element on and off is configured to generate a first command which is a voltage command for a target voltage of the AC voltage, generate a triangular wave carrier signal whose frequency is an even multiple of the frequency of a fundamental wave component of the first command, and generate the gate signal from the carrier signal and a second command composed of a harmonic signal including at least one odd-number multiple harmonic signal whose frequency is an odd-number multiple of the frequency of the fundamental wave component of the first command and at least one even-number multiple harmonic signal whose frequency is an even multiple of the frequency of the fundamental wave component of the first command, and the first command. Effect of the Invention

[0009] According to the present disclosure, even when the number of pulses is an even number, a simple configuration using triangular wave comparison type PWM control mounted on a general-purpose controller IC can control load noise and losses, and when the load is a rotating machine, the noise, torque pulsation, vibration, and losses of the rotating machine can be controlled. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of a power conversion device according to a first embodiment. [Diagram 2] 4 is a diagram for explaining the operation of a gate signal generating means of the power conversion device according to the first embodiment. FIG. [Diagram 3] 2 is a block diagram showing a configuration of a carrier signal generating means of the power conversion device according to the first embodiment. FIG. [Figure 4] 3 is a diagram showing a carrier signal generated by a carrier signal generating means of the power conversion device according to the first embodiment. FIG. [Diagram 5] 3 is a diagram showing an example of a carrier signal generated by a carrier signal calculation unit of the power conversion device according to the first embodiment. FIG. [Figure 6] 2 is a block diagram showing a configuration of a modulated voltage generating means of the power conversion device according to the first embodiment. FIG. [Figure 7] FIG. 7A is a diagram showing an example of a second command value Mu of a conventional power conversion device, and FIG. 7B is a diagram showing an output voltage waveform of the power conversion device controlled by the second command value Mu of FIG. 7A. [Figure 8] FIG. 7C is a diagram showing harmonics contained in the output voltage waveform output by the conventional power conversion device shown in FIG. 7B. [Figure 9] 2 is a diagram showing an example of an output voltage waveform output by the power conversion device according to the first embodiment. [Figure 10] 10 is a diagram showing harmonics contained in an output voltage waveform output by the power conversion device according to the first embodiment shown in FIG. 9. FIG. [Figure 11]FIG. 11A is a diagram showing an example of a second command value Mu of the power conversion device according to embodiment 1, and FIG. 11B is a diagram showing an output voltage waveform of the power conversion device according to embodiment 1 controlled by the second command value Mu of FIG. 11A. [Figure 12] 12A is a diagram showing the magnitude of the harmonic components contained in the second command value Mu of FIG. 11A, and FIG. 12B is a diagram showing the phase of the harmonic components contained in the second command value Mu of FIG. 11A. [Figure 13] FIG. 11 is a block diagram showing a configuration of a power conversion device according to a second embodiment. [Figure 14] FIG. 11 is a block diagram showing a configuration of a carrier signal generating means of a power conversion device according to a second embodiment. [Figure 15] 11 is a diagram showing an example of a carrier signal generated by a carrier signal calculation unit of a power conversion device according to the second embodiment. FIG. [Figure 16] FIG. 11 is a block diagram showing a configuration of a modulated voltage generating means of a power conversion device according to a second embodiment. [Figure 17] FIG. 17A is a diagram showing an example of a second command value Mu of a conventional power conversion device, and FIG. 17B is a diagram showing an output voltage waveform of the power conversion device controlled by the second command value Mu of FIG. 17A. [Figure 18] FIG. 17C is a diagram showing harmonics contained in the output voltage waveform output by the conventional power conversion device shown in FIG. 17B. [Figure 19] 11 is a diagram showing an example of an output voltage waveform output by a power conversion device according to a second embodiment. FIG. [Figure 20] 20 is a diagram showing harmonics contained in an output voltage waveform output by the power conversion device according to the first embodiment shown in FIG. 19. FIG. [Figure 21] FIG. 21A is a diagram showing an example of a second command value Mu of a power conversion device according to embodiment 2, and FIG. 21B is a diagram showing an output voltage waveform of a power conversion device according to embodiment 2 controlled by the second command value Mu of FIG. 21A. [Figure 22] 22A is a diagram showing the magnitude of the harmonic components contained in the second command value Mu of FIG. 21A, and FIG. 22B is a diagram showing the phase of the harmonic components contained in the second command value Mu of FIG. 21A. [Diagram 23] FIG. 11 is a block diagram showing a configuration of a power conversion device according to a third embodiment. [Figure 24] FIG. 11 is a block diagram showing a configuration of a modulated voltage generating means of a power conversion device according to a third embodiment. [Diagram 25] 2 is a block diagram showing an example of a hardware configuration of a power conversion device according to the present disclosure. FIG. [Figure 26] 13 is a block diagram showing another example of a hardware configuration of a power conversion device according to the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Embodiment 1 Fig. 1 is a block diagram showing the configuration of a power conversion device according to a first embodiment. The power conversion device 1A includes an inverter circuit 3 connected to a DC power supply 2 and a rotating machine 4, which is a load, and a drive controller 10 which constitutes a voltage command generating means 5, a carrier signal generating means 6A, a modulated voltage generating means 7A, and a gate signal generating means 8. The drive controller 10 controls the on / off of a semiconductor switching element Q, which will be described next. The DC power supply 2 applies a DC voltage vdc to the inverter circuit 3. The DC power supply 2 may be any device that outputs a DC voltage Vdc, such as a battery, a DC-DC converter, a diode rectifier, or a PWM rectifier.

[0012] The inverter circuit 3 converts the DC power of the DC power source 2 into AC power and supplies the power to the rotating machine 4. Here, the number of phases of the inverter circuit 3 is three, and the phases are defined as u-phase, v-phase, and w-phase. However, the number of phases of the inverter circuit 3 does not have to be three, and may be the same as the number of phases of the rotating machine 4. The inverter circuit 3 is configured such that legs, each of which has two reversely conductive semiconductor switching elements Q connected in series between the positive and negative terminals of the DC power source 2, are connected in parallel in the same number as the number of phases. In this example, since the number of phases of the inverter circuit 3 is three, the inverter circuit 3 has six semiconductor switching elements Q, and as shown in FIG. 1, the six semiconductor switching elements Q are referred to as semiconductor switching elements Qup, Qun, Qvp, Qvn, Qwp, and Qwn. Moreover, a series connection of a positive-side semiconductor switching element Qup and a negative-side semiconductor switching element Qun corresponding to the u-phase is referred to as leg 31u, a series connection of a positive-side semiconductor switching element Qvp and a negative-side semiconductor switching element Qvn corresponding to the v-phase is referred to as leg 31v, and a series connection of a positive-side semiconductor switching element Qwp and a negative-side semiconductor switching element Qwn corresponding to the w-phase is referred to as leg 31w. The intermediate terminals of each leg are connected to each phase of the rotating machine 4.

[0013] Here, each semiconductor switching element Q is composed of an IGBT (Insulated Gate Bipolar Transistor) and an anti-parallel diode. In addition, when a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), an RC (Reverse Conducting)-IGBT, or the like is used instead of the IGBT, the anti-parallel diode may be omitted. Furthermore, each semiconductor switching element may be composed of a wide band gap semiconductor such as SiC or GaN. In the case of a wide band gap semiconductor, in addition to being able to reduce the loss of the semiconductor switching element, the dead time can be shortened by the high-speed switching operation, so that the effect of reducing the error between the command of the switching operation of the present disclosure and the actual switching operation can be obtained.

[0014] The rotating machine 4 has a stator consisting of three-phase stator windings, u-phase, v-phase, and w-phase, and a rotor that rotates due to a rotating magnetic field generated by an AC current flowing through the stator winding. The number of phases of the stator winding does not have to be three, and the stator winding may be configured with two or more sets. The load does not have to be a rotating machine, and may be a load composed of a resistor or a coil.

[0015] For example, when the load is a rotating machine, the voltage command generating means 5 calculates first commands vu*, vv*, vw*, which are phase voltage commands that are sinusoidal, i.e., mainly composed of fundamental sinusoidal components, as the voltage to be supplied to the rotating machine 4 as shown in equation (1) based on one or more operation commands of the torque, rotational speed, position, current amplitude, phase, and frequency of the rotating machine 4, and outputs the calculated vu*, vv*, vw* to the carrier signal generating means 6A and the modulated voltage generating means 7A, respectively. In equation (1), vphp represents the amplitude of the first commands vu*, vv*, vw*, and θv represents the fundamental wave phase of the u-phase.

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[0016] The voltage command generating means 5 may be configured to feed back to the voltage command generating means 5 at least one of the detected or estimated values ​​of the torque, rotational speed, position, amplitude, phase, and frequency of the rotating machine 4, and to calculate the first commands vu*, vv*, and vw* by feedback control based on the operation command and the detected or estimated values. For example, the first commands vu*, vv*, and vw* may be calculated by known current feedback control, speed feedback control, or position feedback control. The first commands vu*, vv*, and vw* are not limited to sine waves, and may be waveforms containing harmonic components in a sine wave. In addition, when the load is other than a rotating machine, since there is no torque parameter, the voltage command generating means 5 may calculate the first commands vu*, vv*, and vw*, which are sine wave phase voltage commands as voltages to be supplied to the load, from at least one of the operation commands of the amplitude, phase, and frequency of the voltage and current.

[0017] The carrier signal generating means 6A generates a triangular wave carrier signal c based on the first commands vu*, vv*, vw*, and outputs the generated carrier signal c to the gate signal generating means 8.

[0018] The modulation voltage generating means 7A generates second commands mu, mv, mw, which are phase voltage commands for modulation, based on the first commands vu*, vv*, vw*, and outputs the generated second commands mu, mv, mw to the gate signal generating means 8. Since the amplitudes of the second commands mu, mv, mw need to be changed according to the magnitude of the DC voltage vdc, the DC voltage vdc may be detected by a voltage sensor, and the first commands vu*, vv*, vw* may be normalized by dividing the first commands vu*, vv*, vw* by half the detected DC voltage vdc.

[0019] The gate signal generating means 8 generates gate signals gup, gun, gvp, gvn, gwp, and gwn (sometimes collectively referred to as gate signals g) that control the on and off of the semiconductor switching element Q of the inverter circuit 3 by comparing the magnitude of the second commands mu, mv, and mw with the magnitude of the carrier signal c. The gate signals gup, gun, gvp, gvn, gwp, and gwn correspond to the semiconductor switching elements Qup, Qun, Qvp, Qvn, Qwp, and Qwn, respectively, and turn on or off the corresponding semiconductor switching elements Q. The gate signals gup, gun, gvp, gvn, gwp, and gwn each have a high value "H" or a low value "L". When the value of the gate signal g is "H", the semiconductor switching element Q corresponding to the gate signal g is controlled to be on, and when the value of the gate signal g is "L", the semiconductor switching element Q corresponding to the gate signal g is controlled to be off.

[0020] FIG. 2 is a diagram for explaining the operation of the gate signal generating means 8 shown in FIG. 1. FIG. 2 shows one u-phase. The gate signal generating means 8 compares the second command mu with the carrier signal c to generate the gate signals gup and gun. Specifically, when the second command mu is greater than the carrier signal c, the value of the gate signal gup is set to "H" and the value of the gate signal gun is set to "L", and when the second command mu is smaller than the carrier signal c, the value of the gate signal gup is set to "L" and the value of the gate signal gun is set to "H". The gate signals gup and gun are complementary to each other. That is, when the gate signal gup is "H", the gate signal gun is set to "L", and when the gate signal gup is "L", the gate signal gun is set to "H". When the gate signal gup is “H”, the positive side semiconductor switching element Qup turns on and the output phase voltage vu becomes vdc, and when the gate signal gun is “H”, the negative side semiconductor switching element Qun turns on and the output phase voltage vu becomes 0.

[0021] Fig. 3 is a block diagram showing the configuration of the carrier signal generating means 6A shown in Fig. 1. The carrier signal generating means 6A includes a three-phase to two-phase conversion unit 601, a phase calculation unit 602, and a carrier signal calculation unit 603A. The three-phase to two-phase conversion unit 601 performs three-phase to two-phase conversion from first commands vu*, vv*, and vw* on the three-phase coordinate to first commands vα* and vβ* on the two-phase coordinate. Specifically, the three-phase to two-phase conversion unit 601 can perform three-phase to two-phase conversion using equation (2).

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[0022] The phase calculation unit 602 calculates the fundamental wave phase θv of the u-phase of the first commands vα* and vβ* on the two-phase coordinate. Specifically, as shown in equation (3), the arctangent calculation is performed on the first commands vα* and vβ* on the two-phase coordinate to obtain the phase of vα*. This phase is the same as the phase of vu*.

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[0023] In this description, it is assumed that the first commands vu*, vv*, vw* and the first commands vα*, vβ* have waveforms with sufficiently few harmonic components and are the same as the fundamental wave components. If the first commands vu*, vv*, vw* and the first commands vα*, vβ* contain many harmonic components, the fundamental wave components can be extracted by passing them through a low-pass filter, for example.

[0024] The carrier signal calculation unit 603A calculates a carrier signal c whose frequency is an even number Kc times the fundamental wave components of the first commands vu*, vv*, and vw*. Specifically, the fundamental wave phase θv is multiplied by the even number Kc as shown in equation (4) to generate the phase θc of the carrier signal.

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[0025] Then, the carrier signal calculation unit 603A generates a triangular carrier signal c as shown in FIG. 4. FIG. 4 is a diagram showing the carrier signal generated by the carrier signal calculation unit 603A shown in FIG. 3. The carrier signal c is a triangular wave with one cycle being 1 / Kc cycle of the fundamental wave components of the first commands vu*, vv*, and vw*, and has a maximum value when the phase θc of the carrier signal is 0° and 360°, a minimum value when it is 180°, and a median value when it is 90° and 270°. In the example shown in FIG. 3, the maximum value of the triangular wave is 1, the minimum value is -1, and the median value is zero. The carrier signal calculation unit 603A outputs the carrier signal c to the gate signal generation means 8.

[0026] In the first embodiment, as an example, the even number Kc is set to 6, and the phase of the carrier signal c is synchronized to the phase 0° of the fundamental wave component of the first command vu*, that is, the median value of the triangular wave. In this case, the carrier signal is as shown in FIG. 5. FIG. 5 is a diagram showing an example of the carrier signal c generated by the carrier signal calculation unit 603A shown in FIG. 3. In addition, in the first embodiment, the carrier signal c is synchronized to the fundamental wave phase θv of the first command vu*, and a common carrier signal c is used in three phases. In this case, since the phase difference between each phase is 120°, in order to generate a similar output phase voltage waveform in each phase, the even number Kc that determines the frequency of the carrier signal c may be set to a multiple of 6. Note that, when individual carrier signals c are used in three phases, it is not necessary to set the even number Kc that determines the frequency of the carrier signal c to a multiple of 6, and Kc may be set to any even number in each phase.

[0027] Fig. 6 is a diagram showing the configuration of the modulated voltage generating means 7A shown in Fig. 1. The modulated voltage generating means 7A includes a three-phase to two-phase conversion section 701, an amplitude calculation section 702, a phase calculation section 703, a fundamental wave signal calculation section 704, an odd-numbered harmonic signal calculation section 705, and an even-numbered harmonic signal calculation section 706A.

[0028] The three-phase to two-phase conversion unit 701 performs three-phase to two-phase conversion from first commands vu*, vv*, vw* which are sinusoidal phase voltage commands on the three-phase coordinates to first commands vα*, vβ* on the two-phase coordinates by processing similar to that of the three-phase to two-phase conversion unit 601, and outputs the first commands vα*, vβ* on the two-phase coordinates to the amplitude calculation unit 702 and the phase calculation unit 703.

[0029] The amplitude calculation unit 702 first calculates the amplitude vphp of the first commands vu*, vv*, and vw* from the first commands vα* and vβ* on the two-phase coordinates. For example, the amplitude calculation unit 702 can calculate the amplitude vphp of the first commands vu*, vv*, and vw* using the following equation (5).

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[0030] Next, the amplitude calculation unit 702 divides the calculated amplitude vphp of the first commands vu*, vv*, vw* by half the DC voltage vdc as shown in the following equation (6), converts it into a normalized amplitude M of the first commands vu*, vv*, vw*, and outputs the calculated amplitude M to the fundamental wave signal calculation unit 704, the odd multiple harmonic signal calculation unit 705, and the even multiple harmonic signal calculation unit 706A.

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[0031] The phase calculation unit 703 calculates the fundamental wave phase θv of the u-phase of the first commands vα*, vβ* on the two-phase coordinate system by processing similar to that of the phase calculation unit 602, and outputs the fundamental wave phase θv as the calculation result to the fundamental wave signal calculation unit 704, the odd multiple harmonic signal calculation unit 705, and the even multiple harmonic signal calculation unit 706A.

[0032] The fundamental wave signal calculation unit 704 calculates fundamental wave signals mu_1, mv_1, mw_1, which are the fundamental wave components of the first commands vu*, vv*, vw*, based on the amplitude M of the normalized first commands vu*, vv*, vw* and the fundamental wave phase θv of the u-phase.

[0033] The odd-multiple harmonic signal calculation unit 705 calculates odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, whose frequencies are odd multiples of the fundamental wave component of the first commands vu*, vv*, vw*, based on the amplitude M of the normalized first commands vu*, vv*, vw* and the fundamental wave phase θv of the u-phase.

[0034] The even-multiple harmonic signal calculation unit 706A calculates even-multiple harmonic signals mu_even, mv_even, mw_even, whose frequencies are even multiples of the fundamental wave component of the first commands vu*, vv*, vw*, based on the amplitude M of the normalized first commands vu*, vv*, vw* and the fundamental wave phase θv of the u-phase.

[0035] Then, the modulated voltage generating means 7A adds together the fundamental signals mu_1, mv_1, mw_1, odd harmonic signals mu_odd, mv_odd, mw_odd and even harmonic signals mu_even, mv_even, mw_even calculated by the fundamental signal calculation unit 704, the odd harmonic signal calculation unit 705 and the even harmonic signal calculation unit 706A, respectively, as shown in equation (7), to generate second commands mu, mv, mw, and output the generated second commands mu, mv, mw to the gate signal generating means 8.

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[0036] Hereinafter, we will explain in order the fundamental signals mu_1, mv_1, mw_1, odd harmonic signals mu_odd, mv_odd, mw_odd and even harmonic signals mu_even, mv_even, mw_even calculated by fundamental signal calculation unit 704, odd harmonic signal calculation unit 705 and even harmonic signal calculation unit 706A of modulated voltage generating means 7A.

[0037] 7A and 7B are diagrams showing an example of a phase voltage (FIG. 7B) output by a conventional power conversion device as a comparative example when the sinusoidal first command vu* is directly given to the gate signal generating means 8 as the second command mu (FIG. 7A). In FIG. 7A and FIG. 7B, the amplitude M of the normalized first commands vu*, vv*, and vw* is 0.6, and the waveform of the phase voltage output when the gate signal g is generated from the second commands mu, mv, and mw using the carrier signal c and the gate signal generating means 8 to operate the inverter circuit 3 is shown for the u-phase component. FIG. 7A shows the sinusoidal second command mu and the triangular carrier signal c, and FIG. 7B shows the output phase voltage vu output based on the sinusoidal second command mu and the triangular carrier signal c. Here, α1 to α11 shown in FIG. 7B represent the switching phases. When the carrier signal c of this embodiment is used, switching is performed 11 times in one period of the second command mu. Among them, when the fundamental wave phase θv is 180°, the second command mu and the carrier signal c always pass through 0, so the switching phase α6 is always 180°. In addition, since the output phase voltage vu is positive and negative symmetrical from phase 0° to 180° and from phase 180° to 360°, if the switching phases α1 to α5 are determined, the switching phases α7 to α11 are also determined. Therefore, in order to obtain an output phase voltage vu that reduces the amplitude of the predetermined frequency components of the voltage, current, torque, loss, vibration, voltage, and current of the rotating machine 4, which will be described below, and the voltage and current of the DC power supply, the switching phases α1 to α5 can be appropriately adjusted. Note that, when the load is other than the rotating machine 4, there is no torque parameter, so the switching phases α1 to α5 can be appropriately adjusted so that the voltage, current, loss, and amplitude of the predetermined frequency components of the load, voltage, and current of the DC power supply are reduced.

[0038] According to the technology disclosed herein, it is possible to freely control the harmonic components generated by switching. Therefore, if for some reason it is desired to increase the load noise and loss due to harmonic components, or if the load is a rotating machine, if it is desired to increase the rotating machine noise, torque pulsation, vibration, and loss due to harmonic components, the technology disclosed herein can be applied in the same manner as in reducing these. If it is desired to increase noise, loss, etc., it is sufficient to appropriately adjust the switching phases α1 to α5 to obtain an output phase voltage vu that increases the amplitude of a specified frequency component. In other words, compared to the case where a gate signal is generated by comparing a carrier signal with a sine wave modulated signal of the fundamental wave component of the first command to operate the power conversion device, the drive controller can be configured to generate the second command so that, when the load is a rotating machine, the amplitude of a predetermined frequency component included in at least one parameter of the rotating machine's voltage, current, torque, loss, vibration, or DC voltage or DC current flowing on the DC side is reduced or increased; and, when the load is other than a rotating machine, the amplitude of a predetermined frequency component included in at least one parameter of the load's voltage, current, loss, DC voltage, or DC current flowing on the DC side is reduced or increased.

[0039] FIG. 8 is a diagram showing the magnitude of the harmonic components included in the output phase voltage vu shown in FIG. 7B. The horizontal axis of FIG. 8 indicates the order relative to the fundamental wave, and the vertical axis indicates the magnitude of the harmonic components. From FIG. 8, it can be seen that the output phase voltage vu shown in FIG. 7B includes odd-numbered and even-numbered harmonic components. In addition, it can be seen that, excluding the integer multiple component of 3 that does not appear in the harmonic components of the phase current flowing through the rotating machine 4, the 11th-order and 13th-order harmonics are particularly large. Therefore, in this embodiment, as an example, it is assumed that the 11th-order and 13th-order harmonic components relative to the fundamental wave component of the output phase voltage vu excite the mechanical resonance of the rotating machine 4, causing large noise or torque pulsation, and also increasing the loss of the rotating machine 4, and the switching phases α1 to α5 are adjusted so that the 11th-order and 13th-order harmonic components of the output phase voltage vu are reduced.

[0040] In order to find the switching phases α1 to α5 that reduce the 11th and 13th harmonic components of the output phase voltage vu, for example, an optimization problem may be solved to minimize the objective function fobj(α) expressed by equation (8).

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[0041] In this embodiment, p in equation (8) is set to 50, and the objective function fobj(α) is set so as to minimize the total harmonic distortion for the 2nd to 50th harmonic voltages. In addition, by increasing the weighting coefficients of the 11th and 13th orders as shown in equation (10), the 11th and 13th harmonic components are preferentially reduced.

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[0042] FIG. 9 is a diagram showing an example of an output phase voltage vu in which switching phases α1 to α5 are adjusted so that the 11th and 13th harmonic components are minimized. FIG. 10 is a diagram showing the magnitude of the harmonic components included in the output phase voltage vu shown in FIG. 9. The horizontal axis of FIG. 10 represents the order relative to the fundamental wave, and the vertical axis represents the magnitude of the harmonic components. As shown in FIG. 9, by solving an optimization problem so as to minimize the objective function fobj(α) expressed by equation (8), it can be seen that these switching phases are changed from the switching phases α1 to α5 of the output phase voltage vu shown in FIG. 7B. Also, as shown in FIG. 10, it can be seen that the 11th and 13th harmonic components can be reduced compared to the magnitude of the harmonic components shown in FIG. 8. Therefore, the second command mu may be generated so that the output phase voltage vu shown in FIG. 9 can be output using triangular wave comparison type PWM.

[0043] 11A and 11B are diagrams showing an example of a phase voltage (FIG. 11B) output by the power conversion device 1A when the second command mu (FIG. 11A) generated so that the output phase voltage vu shown in FIG. 9 can be output is given to the gate signal generating means 8. In FIG. 11A and FIG. 11B, the waveform of the phase voltage output when the gate signal g is generated from the second commands mu, mv, and mw using the carrier signal c and the gate signal generating means 8 and the inverter circuit 3 is operated in the case where the amplitude M of the normalized first commands vu*, vv*, and vw* is 0.6 is shown for the u-phase component. FIG. 11A shows the second command mu and the triangular wave carrier signal c, and FIG. 11B shows the output phase voltage vu output based on the second command mu and the triangular wave carrier signal c. By performing triangular wave comparison type PWM using the second command mu shown in FIG. 11A, it is possible to output a waveform similar to the output phase voltage vu shown in FIG. 9.

[0044] In the above, as an example of the waveform of the second command, a waveform in which the value of the second command mu does not change and is a constant value in each period in which the carrier signal c changes from the minimum value to the maximum value and in each period in which the carrier signal c changes from the maximum value to the minimum value, that is, a case in which the waveform of the second command mu is a stepped waveform, has been described. However, if the output phase voltage vu shown in Fig. 9 can be output, that is, if the phase in which the second command mu crosses the carrier signal c is the phase of each switching phase α in Fig. 9, the second command mu does not need to have a constant value in a half cycle of the carrier signal c, and may be a waveform that changes smoothly.

[0045] 12A and 12B are diagrams showing the magnitude and phase of the harmonic components of the second command mu shown in FIG. 11A. The horizontal axis of FIG. 12A and FIG. 12B is the order relative to the fundamental wave. The vertical axis of FIG. 12A represents the magnitude of the harmonic components, and the vertical axis of FIG. 12B represents the phase of the harmonic components when the sine wave is used as a reference. From FIG. 12A, it can be seen that the second command mu is composed of a fundamental wave component, an odd-multiple harmonic component, and an even-multiple harmonic component. From FIG. 12B, it can be seen that the fundamental wave component, the odd-multiple harmonic component, and the even-multiple harmonic component of the second command mu are all composed of sine wave components (sine waves in which the phase 0° of each harmonic component is synchronized with the phase 0° of the fundamental wave component).

[0046] Therefore, the fundamental signal calculation unit 704, odd-multiple harmonic signal calculation unit 705, and even-multiple harmonic signal calculation unit 706A of the modulated voltage generation means 7A only need to calculate the fundamental signal mu_1, odd-multiple harmonic signal mu_odd, and even-multiple harmonic signal mu_even, respectively, as shown in equation (11), where q is a value set so that 2q+1 is the maximum order considered, M1 is the amplitude of the fundamental signal mu_1, M2n+1 is the amplitude of the odd-multiple harmonic signal mu_odd at the 2n+1th order, and M2n is the amplitude of the even-multiple harmonic signal mu_even at the 2nth order.

number

[0047] As described above, the harmonic signals of each order of the odd-multiple harmonic signal mu_odd and the even-multiple harmonic signal mu_even in this embodiment are preferably sine waves, and the phase zero of the harmonic signal of each order may be synchronized with the phase zero of the fundamental wave component of the first command vu*. Furthermore, the harmonic signals of each order of the odd-multiple harmonic signal mu_odd and the even-multiple harmonic signal mu_even are not limited to sine waves and may be distorted waveforms, and may be periodic signals in which the value at the start and end of one cycle of the fundamental wave component of the first command is the same and there is at least one point where one cycle crosses zero.

[0048] The odd-multiple harmonic signal mu_odd and the even-multiple harmonic signal mu_even constituting the second command preferably use a relatively large value for q in equation (11), i.e., are composed of a plurality of odd-multiple harmonic signals and a plurality of even-multiple harmonic signals. However, as long as the odd-multiple harmonic signal mu_odd and the even-multiple harmonic signal mu_even each contain at least one order harmonic signal, the switching phase can be controlled to control the harmonic components generated by switching, as compared to conventional synchronous PWM, and the effect of the present disclosure of increasing or decreasing the noise and loss of the load can be achieved.

[0049] In this embodiment, only the second command mu for the u phase has been described, but since the waveforms of the three-phase second commands mu, mv, and mw are waveforms in which the phases of the fundamental wave components are shifted from each other by 120°, the second commands mv and mw for the remaining two phases can also be generated in the same way as the second command mu.

[0050] As described above, according to the power conversion device of the first embodiment, even when the triangular wave carrier signal is an even multiple of the fundamental wave frequency, i.e., the number of pulses of the output voltage per one cycle of the fundamental wave is even, it is possible to control a predetermined order harmonics of the voltage or current generated by PWM with a relatively simple configuration using a triangular wave comparison type PWM mounted on a general-purpose controller IC. This makes it possible to control the noise and loss of the load, and when the load is a rotating machine, it is possible to control the noise, torque pulsation, vibration, and loss of the rotating machine.

[0051] Embodiment 2 13 is a diagram showing a configuration of a power conversion device 1B according to embodiment 2. The power conversion device 1B includes an inverter circuit 3 connected to a DC power supply 2 and a rotating machine 4, which is a load, a voltage command generating means 5, a carrier signal generating means 6B, a modulated voltage generating means 7B, and a gate signal generating means 8.

[0052] Power conversion device 1B has carrier signal generating means 6B having a different function from carrier signal generating means 6A of power conversion device 1A according to embodiment 1, and has modulated voltage generating means 7B having a different function from modulated voltage generating means 7A. Below, a description of the parts common to power conversion device 1A according to embodiment 1 will be omitted, and the following mainly describes the parts that differ from power conversion device 1A.

[0053] Fig. 14 is a block diagram showing the configuration of the carrier signal generating means 6B shown in Fig. 13. The carrier signal generating means 6B includes a three-phase to two-phase conversion unit 601, a phase calculation unit 602, and a carrier signal calculation unit 603B. The carrier signal generating means 6B has a slightly different function from the carrier signal calculation unit 603A of the carrier signal generating means 6A according to the first embodiment.

[0054] The function of the carrier signal calculation unit 603B is basically the same as that of the carrier signal calculation unit 603A, and the even number Kc that determines the frequency of the carrier signal is 6. In the carrier signal calculation unit 603A, the phase 90° of the carrier signal c, i.e., the median value of the triangular wave, is synchronized with the phase 0° of the fundamental wave component of the first command vu*, but in the carrier signal calculation unit 603B according to the second embodiment, the phase 180° of the carrier signal c, i.e., the minimum value of the triangular wave, is synchronized with the phase 0° of the fundamental wave component of the first command vu*. At this time, the carrier signal becomes as shown in FIG. 15. FIG. 15 is a diagram showing an example of the carrier signal c generated by the carrier signal calculation unit 603B shown in FIG. 14. Also, in the second embodiment, as in the first embodiment, the carrier signal c is synchronized with the fundamental wave phase θv of the first command vu*, and a carrier signal c common to the three phases is used. In this case, because the phase difference between each phase is 120°, in order to generate similar output phase voltage waveforms for each phase, the even number Kc that determines the frequency of carrier signal c should be set to a multiple of 6. Note that when separate carrier signals c are used for the three phases, it is not necessary to set the even number Kc that determines the frequency of carrier signal c to a multiple of 6.

[0055] Fig. 16 is a diagram showing the configuration of the modulated voltage generating means 7B shown in Fig. 13. The modulated voltage generating means 7B includes a three-phase to two-phase conversion unit 701, an amplitude calculation unit 702, a phase calculation unit 703, a fundamental wave signal calculation unit 704, an odd-multiple harmonic signal calculation unit 705, and an even-multiple harmonic signal calculation unit 706B. The even-multiple harmonic signal calculation unit 706B has an even-multiple harmonic signal calculation unit 706B whose function is slightly different from that of the even-multiple harmonic signal calculation unit 706A according to the first embodiment. The function of the even-multiple harmonic signal calculation unit 706B is basically the same as that of the even-multiple harmonic signal calculation unit 706A described in the first embodiment, but the even-multiple harmonic signals mu_even, mv_even, and mw_even that are calculated are different.

[0056] 17A and 17B are diagrams showing an example of a phase voltage (FIG. 17B) output by the power conversion device 1B when the sinusoidal first command vu* is directly given to the gate signal generating means 8 as the second command mu (FIG. 17A). FIG. 17B shows a waveform of a phase voltage output when the inverter circuit 3 is operated by generating a gate signal g from the second commands mu, mv, and mw using the carrier signal c and the gate signal generating means 8 in the case where the amplitude M of the normalized first commands vu*, vv*, and vw* is 0.6, for the u-phase component. FIG. 17A shows the sinusoidal second command mu and the triangular carrier signal c, and FIG. 17B shows the output phase voltage vu output based on the sinusoidal second command mu and the triangular carrier signal c. Here, α1 to α12 shown in FIG. 17B represent the switching phases. When the carrier signal c of the second embodiment is used, switching is performed 12 times in one period of the second command mu. The output phase voltage vu is inversion symmetric between the phases 0° to 90° and 90° to 180°, and between the phases 180° to 270° and 270° to 360°. Therefore, if the switching phases α1 to α3 and α7 to α9 are determined, the switching phases α4 to α6 and α10 to α12 are also determined. Therefore, in order to obtain an output phase voltage vu that reduces or increases the amplitude of a specified frequency component of the voltage, current, torque, loss, vibration of the rotating machine 4, and the voltage and current of the DC power supply, the switching phases α1 to α3 and α7 to α9 may be appropriately adjusted. In addition, when the load is other than the rotating machine 4, the switching phases α1 to α3 and α7 to α9 can be appropriately adjusted so that the voltage, current, and loss of the load, and the amplitude of the specified frequency components of the voltage and current of the DC power supply become smaller or larger.

[0057] FIG. 18 is a diagram showing the magnitude of the harmonic components included in the output phase voltage vu shown in FIG. 17B. The horizontal axis of FIG. 18 indicates the order relative to the fundamental wave, and the vertical axis indicates the magnitude of the harmonic components. From FIG. 18, it can be seen that the output phase voltage vu shown in FIG. 17B includes odd-numbered and even-numbered harmonic components. In addition, excluding the integer multiple component of 3 that does not appear in the harmonic components of the phase current flowing through the rotating machine 4, the 11th-order and 13th-order harmonics are particularly large. However, since the first embodiment has already described a case in which the 11th-order and 13th-order harmonic components are reduced, in this embodiment, as an example, it is assumed that the 5th-order and 7th-order harmonic components relative to the fundamental wave component of the output phase voltage vu excite the mechanical resonance of the rotating machine 4, causing large noise or torque pulsation, and also increasing the loss of the rotating machine 4. The switching phases α1 to α3 and α7 to α9 are adjusted so that the 5th-order and 7th-order harmonic components of the output phase voltage vu are reduced.

[0058] In order to find the switching phases α1 to α3 and α7 to α9 that reduce the fifth and seventh harmonic components of the output phase voltage vu, it is sufficient to solve an optimization problem so as to minimize the objective function fobj(α) expressed by, for example, equation (12).

number

[0059] Here, the objective function fobj(α) is set so that the root-sum-of-squares value of the n-th harmonic voltage vn in the range from the second to the pth harmonic voltage divided by the fundamental voltage v1, that is, the total harmonic distortion, is minimized. In addition, kn is a weighting coefficient, and by increasing the weighting coefficient kn of a specific order, it is possible to preferentially reduce harmonics of a specific order. Note that the switching phases α1 to α3 and α7 to α9 are restricted in that there exists a phase where the second command and the carrier signal cross every half cycle of the carrier signal, as shown in equation (13). Therefore, the optimization problem is solved while observing these constraints.

number

[0060] In the second embodiment, the objective function fobj(α) is set so as to minimize the total harmonic distortion for the second to fiftieth harmonic voltages. In addition, the fifth and seventh harmonic components are preferentially reduced by increasing the weighting coefficients for the fifth and seventh harmonic voltages as shown in equation (14).

number

[0061] FIG. 19 is a diagram showing an example of the output phase voltage vu in which the switching phases α1 to α3 and α7 to α9 are adjusted so that the fifth and seventh harmonic components are minimized. FIG. 20 is a diagram showing the magnitude of the harmonic components included in the output phase voltage vu shown in FIG. 18. The horizontal axis of FIG. 20 represents the order relative to the fundamental wave, and the vertical axis represents the magnitude of the harmonic components. By solving an optimization problem so as to minimize the objective function fobj(α) expressed by equation (12), as shown in FIG. 19, each switching phase is changed from the switching phases α1 to α3 and α7 to α9 of the output phase voltage vu shown in FIG. 17B. Also, it can be seen from FIG. 20 that the fifth and seventh harmonic components can be reduced compared to the magnitude of the harmonic components shown in FIG. 18. Therefore, the second command mu may be generated so that the output phase voltage vu shown in FIG. 19 can be output using triangular wave comparison type PWM.

[0062] 21A and 21B are diagrams showing an example of a phase voltage (FIG. 21B) output by the power conversion device 1B when the second command mu (FIG. 21A) generated so that the output phase voltage vu shown in FIG. 19 can be output is given to the gate signal generating means 8. FIG. 21B shows the waveform of the phase voltage output when the inverter circuit 3 is operated by generating the gate signal g from the second commands mu, mv, and mw using the carrier signal c and the gate signal generating means 8 in the case where the amplitude M of the normalized first commands vu*, vv*, and vw* is 0.6, for the u-phase component. FIG. 21A shows the second command mu and the triangular wave carrier signal c, and FIG. 21B shows the output phase voltage vu output based on the second command mu and the triangular wave carrier signal c. It can be seen that the triangular wave comparison type PWM using the second command mu and the triangular wave carrier signal c shown in FIG. 21A can output a waveform similar to the output phase voltage vu shown in FIG. 19.

[0063] In this embodiment, as an example of the waveform of the second command, a waveform in which the value of the second command mu does not change and is constant during the period in which the carrier signal c changes from the minimum value to the maximum value and during the period in which the carrier signal c changes from the maximum value to the minimum value, that is, a step-shaped waveform of the second command mu, has been described. However, if the output phase voltage shown in Fig. 19 can be output, that is, if the second command mu is such that the phase at which the second command mu crosses the carrier signal c is the phase of each switching phase α in Fig. 19, it goes without saying that the second command mu does not need to be constant over a half cycle of the carrier signal c, and may be a waveform that changes smoothly.

[0064] 22A and 22B are diagrams showing the magnitude (FIG. 22A) and phase (FIG. 22B) of the harmonic components of the second command mu shown in FIG. 21A. The horizontal axis of FIG. 22A and FIG. 22B is the order relative to the fundamental wave. The vertical axis of FIG. 21A represents the magnitude of the harmonic components, and the vertical axis of FIG. 22B represents the phase of the harmonic components when the sine wave is used as a reference. As shown in FIG. 22A, the second command mu is composed of a fundamental wave component, an odd-multiple harmonic component, and an even-multiple harmonic component. As shown in FIG. 22B, the fundamental wave component and the odd-multiple harmonic component of the second command mu are composed of sine wave components whose phase 0° is synchronized, and the even-multiple harmonic component is composed of sine wave components whose phase minus 90° is synchronized with the phase 0° of the fundamental wave component.

[0065] Therefore, the fundamental signal calculation unit 704, odd-multiple harmonic signal calculation unit 705, and even-multiple harmonic signal calculation unit 706B of the modulated voltage generation means 7B need only calculate the fundamental signal mu_1, odd-multiple harmonic signal mu_odd, and even-multiple harmonic signal mu_even as shown in equation (15), where q is a value set so that 2q+1 is the maximum order considered, M1 is the amplitude of the fundamental signal mu_1, M2n+1 is the amplitude of the odd-multiple harmonic signal mu_odd at the 2n+1th order, and M2n is the amplitude of the even-multiple harmonic signal mu_even at the 2nth order.

number

[0066] In this embodiment, the harmonic signals of each order of the odd-multiple harmonic signal mu_odd are sine waves, and the phases are synchronized with the phase zero of the fundamental wave component of the first command vu*. In addition, if the harmonic signals of each order of the even-multiple harmonic signal mu_even described as cosine waves in equation (15) are sine waves, the phase minus 90° of the sine wave of the harmonic signals of each order can be synchronized with the phase zero of the fundamental wave component of the first command vu*. Furthermore, the harmonic signals of each order of the odd-multiple harmonic signal mu_odd and the even-multiple harmonic signal mu_even are not limited to sine waves and may be distorted waveforms, and may be periodic signals in which the start and end of one cycle of the fundamental wave component of the first command have the same value and cross zero at least once in one cycle. Furthermore, if the odd-multiple harmonic signal mu_odd and the even-multiple harmonic signal mu_even each contain at least one harmonic signal of one order, the switching phase can be controlled to control the harmonic components generated by switching, as compared to conventional synchronous PWM, thereby achieving the effect of the present disclosure of increasing or decreasing load noise, losses, etc.

[0067] In this second embodiment, only the second command mu has been described, but since the waveforms of the three-phase second commands mu, mv, and mw are waveforms in which the phases of the fundamental wave components are shifted from each other by 120°, the second commands mv and mw of the remaining two phases can also be generated in the same way as the second command mu.

[0068] As described above, in the power conversion device 1B according to the second embodiment, the phase of the carrier signal c is shifted by 90° compared to the power conversion device 1A according to the first embodiment. However, even in such a case, when the number of pulses is an even number, it is possible to control a predetermined order of harmonics of the voltage or current generated by PWM with a relatively simple configuration using a triangular wave comparison type PWM mounted on a general-purpose controller IC. This provides the effect of controlling the noise, torque pulsation, vibration, and loss of the rotating machine when the load is a rotating machine.

[0069] Embodiment 3 23 is a diagram showing a configuration of a power conversion device 1C according to embodiment 3. The power conversion device 1C includes an inverter circuit 3 connected to a DC power supply 2 and a rotating machine 4 as a load, a voltage command generating means 5, a carrier signal generating means 6A, a modulated voltage generating means 7C, and a gate signal generating means 8.

[0070] The power conversion device 1C has a modulated voltage generating means 7C having a different function from the modulated voltage generating means 7A of the power conversion device 1A according to embodiment 1. Below, the description of the parts common to the power conversion device 1A according to embodiment 1 will be omitted, and the description will be mainly focused on the parts different from the power conversion device 1A.

[0071] Fig. 24 is a block diagram showing the configuration of the modulated voltage generating means 7C shown in Fig. 23. The modulated voltage generating means 7C includes a three-phase to two-phase conversion unit 701, an amplitude calculation unit 702, a phase calculation unit 703, a storage unit 707, and a modulated voltage calculation unit 708.

[0072] The memory unit 707 stores the waveforms of the second commands mu, mv, mw based on the first commands vu*, vv*, vw* or the signals that constitute the second commands mu, mv, mw, and outputs the stored waveforms of the second commands mu, mv, mw or the signals that constitute the second commands mu, mv, mw to the modulation voltage calculation unit 708.

[0073] The waveforms of the second commands mu, mv, mw can be obtained by setting the amplitude M of the normalized first commands vu*, vv*, vw*, the fundamental wave phase θv of the u-phase, and the harmonic order to be reduced. Therefore, for example, the waveforms of the second commands mu, mv, mw are obtained in advance as a function of M and θv, or for each M and θv, for each combination of harmonic orders to be reduced. The storage unit 707 then stores the waveforms of the second commands mu, mv, mw based on the amplitude M of the normalized first commands vu*, vv*, vw* and the fundamental wave phase θv of the u-phase. Alternatively, the storage unit 707 stores the waveforms of the fundamental signals mu_1, mv_1, mw_1, odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, and even-multiple harmonic signals mu_even, mv_even, mw_even, which are based on the amplitude M of the normalized first commands vu*, vv*, vw* and the fundamental phase θv of the u phase. Alternatively, the storage unit 707 stores the amplitudes of the fundamental signals mu_1, mv_1, mw_1, odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, and even-multiple harmonic signals mu_even, mv_even, mw_even, which constitute the second commands mu, mv, mw, which are based on the amplitude M of the normalized first commands vu*, vv*, vw*.

[0074] In the third embodiment, the second commands mu, mv, mw are symmetrical in positive and negative between the phases 0° to 180° and 180° to 360°, so only the waveforms of the second commands mu, mv, mw corresponding to a half cycle of the fundamental wave of the first commands vu*, vv*, vw* may be stored. Alternatively, only the waveforms of the fundamental wave signals mu_1, mv_1, mw_1, odd harmonic signals mu_odd, mv_odd, mw_odd, and even harmonic signals mu_even, mv_even, mw_even corresponding to a half cycle of the fundamental wave of the first commands vu*, vv*, vw* may be stored.

[0075] The modulation voltage calculation unit 708 refers to the waveforms of the second commands mu, mv, mw or the signals constituting the second commands mu, mv, mw stored in the memory unit 707 based on the first commands vu*, vv*, vw*, and calculates the second commands mu, mv, mw from the waveforms of the second commands mu, mv, mw or the signals constituting the second commands mu, mv, mw referred to.

[0076] Specifically, as shown in equation (16), the modulation voltage calculation unit 708 refers to the waveforms of the second commands mu, mv, mw stored in the memory unit 707 based on the amplitudes M of the normalized first commands vu*, vv*, vw* and the fundamental wave phase θv of the u phase, i.e., as a function of M and θv or for each value of M and θv, and calculates mu, mv, mw from the referred waveforms of mu, mv, mw.

number

[0077] Alternatively, as shown in equation (17), the modulation voltage calculation unit 708 refers to the waveforms of the fundamental signals mu_1, mv_1, mw_1, odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, and even-multiple harmonic signals mu_even, mv_even, mw_even stored in the memory unit 707 based on the amplitudes M of the normalized first commands vu*, vv*, vw* and the fundamental phase θv of the u-phase, i.e., as a function of M and θv, or for each value of M and θv, and calculates the second commands mu, mv, mw from the waveforms of the fundamental signals mu_1, mv_1, mw_1, odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, and even-multiple harmonic signals mu_even, mv_even, mw_even.

number

[0078] Alternatively, as shown in equation (18), the modulation voltage calculation unit 708 refers to the amplitudes of each order of the fundamental signals mu_1, mv_1, mw_1, odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, and even-multiple harmonic signals mu_even, mv_even, mw_even stored in the memory unit 707 based on the amplitudes M of the normalized first commands vu*, vv*, vw*, i.e., as a function of M or for each value of M, and calculates the second commands mu, mv, mw from the amplitudes of each order of the fundamental signals mu_1, mv_1, mw_1, odd-multiple harmonic signals mu_odd, mv_odd, mw_odd, and even-multiple harmonic signals mu_even, mv_even, mw_even and the fundamental phase θv of the u-phase.

number

[0079] Here, if the memory unit 707 only stores the waveforms of the second commands mu, mv, and mw corresponding to 1 / 2 the cycle of the fundamental wave, the second commands mu, mv, and mw are symmetrical in positive and negative from phase 0° to 180° and from phase 180° to 360°, and the second commands mu, mv, and mw for one cycle of the fundamental wave can be reproduced by referring to the waveforms of the second commands mu, mv, and mw corresponding to half the cycle of the fundamental wave.

[0080] Alternatively, if the memory unit 707 stores only the waveforms of the fundamental wave signals mu_1, mv_1, mw_1, odd harmonic signals mu_odd, mv_odd, mw_odd and even harmonic signals mu_even, mv_even, mw_even corresponding to 1 / 2 a cycle of the fundamental wave, the second commands mu, mv, mw for one cycle of the fundamental wave can be reproduced by referring to the waveforms of the fundamental wave signals mu_1, mv_1, mw_1, odd harmonic signals mu_odd, mv_odd, mw_odd and even harmonic signals mu_even, mv_even, mw_even corresponding to half a cycle of the fundamental wave.

[0081] In addition, since the waveforms of the second commands mu, mv, and mw are waveforms in which the phase of each phase is shifted by 120° from each other, the modulation voltage calculation unit 708 may generate the second command mu based on the fundamental wave phase θv of the u phase, and then generate the second commands mu, mv, and mw for three phases by shifting the phase.

[0082] As described above, according to the power conversion device 1C of the third embodiment, even when the number of pulses is an even number, it is possible to control a predetermined order of harmonics of the voltage or current generated by PWM with a relatively simple configuration using a triangular wave comparison type PWM mounted on a general-purpose controller IC. This has the effect of controlling the noise, torque pulsation, vibration, and loss of the rotating machine. At the same time, since the data for generating the second commands mu, mv, and mw described in the first embodiment is stored in the storage unit 707 in advance, it is possible to reduce the calculation load when calculating the second commands mu, mv, and mw.

[0083] Here, the hardware configuration of the power conversion devices 1A, 1B, and 1C according to the first to third embodiments will be described. Here, the power conversion devices 1A, 1B, and 1C are collectively referred to as the power conversion device 1. The functions of the drive controller 10 in the power conversion device 1, i.e., the voltage command generating means 5, the carrier signal generating means 6A and 6B, the modulated voltage generating means 7A, 7B, and 7C, and the gate signal generating means 8, can be realized using a processing circuit. The processing circuit may be dedicated hardware such as a dedicated processing circuit, or may be a processor and a storage means.

[0084] 25 is a diagram showing a configuration example of the power conversion device 1 when dedicated hardware is used. When dedicated hardware is used, the drive controller 10 is configured with a dedicated processing circuit. The dedicated processing circuit corresponds to a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. Each of the multiple functions of the power conversion device 1 described above may be realized by a different dedicated processing circuit, or the multiple functions of the power conversion device 1 may be realized collectively by a dedicated processing circuit.

[0085] FIG. 26 is a diagram showing a configuration example of the power conversion device 1 when a processor and a storage means are used. When the processor 15 and the storage means 16 are used as the drive controller 10, each function of the power conversion device 1 described above is realized by software, firmware, or a combination of these. The software or firmware is written as a program, and the processor 15 reads and executes the program stored in the storage means 16. It can also be said that these programs cause a computer to execute the procedure or method of each function of the power conversion device 1. The processor 15 is a CPU (Central Processing Unit) and is also called a processing device, an arithmetic device, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), etc. The storage means 16 is, for example, a non-volatile or volatile semiconductor memory such as a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), or an EEPROM (registered trademark) (Electrically EPROM), or a flexible disk, an optical disk, a compact disk, a DVD (Digital Versatile Disk), etc. Furthermore, some of the functions of the power conversion device 1 may be realized by dedicated hardware, and the other may be realized by software or firmware.

[0086] Although various exemplary embodiments and examples are described in this disclosure, various features, aspects, and functions described in one or more embodiments are not limited to application of a specific embodiment, but can be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are expected within the scope of the technology of this disclosure. For example, the following are included: modifying, adding, or omitting at least one component; and extracting at least one component and combining it with components of other embodiments.

[0087] For example, in the above embodiment, the inverter circuit 3 is a three-phase inverter circuit, but it may be an inverter circuit with another number of phases, and various inverter circuits can be used, including multilevel inverters such as a three-level inverter and a five-level inverter.

[0088] In the first and third embodiments, when the carrier signal generating means 6A synchronizes the median of the triangular wave, which is the carrier signal c, with the phase 0° of the first commands vu*, vv*, and vw*, the carrier signal generating means 6A uses the median of the decreasing side of the triangular wave, which is a phase of 90° in the example of FIG. 4. However, the carrier signal generating means 6A may synchronize the median of the ascending side of the triangular wave, which is a phase of 270° in the example of FIG. 4, with the phase 0° of the first commands vu*, vv*, and vw*. In this case, as described in the first embodiment, when the odd-numbered harmonic signal and the even-numbered harmonic signal constituting the second command are sine waves, the phase zero of each harmonic signal is composed of a sine wave synchronized with the phase zero of the fundamental wave component of the first command.

[0089] In the second embodiment, the carrier signal generating means 6B synchronizes the minimum value of the triangular wave, which is the carrier signal c, with the phase 0° of the first commands vu*, vv*, and vw*, which is 180° in the example of FIG. 4. However, the carrier signal generating means 6B may synchronize the maximum value of the triangular wave, which is 0° or 360° in the example of FIG. 4, with the phase 0° of the first commands vu*, vv*, and vw*. In this case, as described in the second embodiment, when the odd-multiple harmonic signal and the even-multiple harmonic signal constituting the second command mu are sine waves, the odd-multiple harmonic component is composed of a sine wave synchronized with the phase 0° of the fundamental wave component, and the even-multiple harmonic component is composed of a sine wave with a phase minus 90° synchronized with the phase 0° of the fundamental wave component. [Explanation of symbols]

[0090] 10 Drive controller, c Carrier signal, mu, mv, mw Second command, Q, Qup, Qun, Qvp, Qvn, Qwp, Qwn Semiconductor switching element, vu*, vv*, vw* First command, g, gup, gun, gvp, gvn, gwp, gwn Gate signal

Claims

1. A power conversion device that converts a DC voltage into an AC voltage by turning on and off a semiconductor switching element, a drive controller for generating a gate signal for driving the semiconductor switching element on and off; generating a first command which is a voltage command for a target voltage of the AC voltage; generating a triangular wave carrier signal having a frequency that is an even multiple of the frequency of the fundamental wave component of the first command; The gate signal is generated from a second command composed of a harmonic signal including at least one odd-multiple harmonic signal having a frequency that is an odd multiple of the frequency of the fundamental wave component of the first command and at least one even-multiple harmonic signal having a frequency that is an even multiple of the frequency of the fundamental wave component of the first command, and the carrier signal. A power conversion device configured as follows.

2. The power conversion device according to claim 1, wherein the odd-harmonic signal and the even-harmonic signal are periodic signals having the same value at the beginning and end of one cycle of the fundamental wave component of the first command and having at least one zero crossing point during one cycle.

3. The power conversion device according to claim 1 , wherein any one of a median value, a minimum value, and a maximum value of a triangular wave of the carrier signal is synchronized with a phase zero of a fundamental wave component of the first command.

4. 2. The power conversion device according to claim 1, wherein the carrier signal has a triangular wave whose median value is synchronized with phase zero of the fundamental wave component of the first command, and the odd-multiple harmonic signal and the even-multiple harmonic signal constituting the second command are sine waves, and phase zero of the sine wave is synchronized with phase zero of the fundamental wave component of the first command.

5. 2. The power conversion device according to claim 1, wherein the minimum or maximum value of a triangular wave of the carrier signal is synchronized with phase zero of the fundamental wave component of the first command, the odd-multiple harmonic signal and the even-multiple harmonic signal constituting the second command are sine waves, the phase zero of the odd-multiple harmonic signal is synchronized with phase zero of the fundamental wave component of the first command, and the phase minus 90° of the even-multiple harmonic signal is synchronized with phase zero of the fundamental wave component of the first command.

6. The power conversion device according to any one of claims 1 to 5, wherein the waveform of the second command is a waveform whose value does not change and remains constant during each period in which the carrier signal changes from a maximum value to a minimum value and during each period in which the carrier signal changes from a minimum value to a maximum value.

7. The drive controller includes:

6. The power conversion device according to claim 1, wherein a second command candidate stored as parameters are an amplitude and a phase of a voltage command of a target voltage within a predetermined range, and the second command is retrieved by referring to the generated first command and used as the second command.

8. The drive controller includes: The power conversion device according to claim 7 , wherein the second command candidates are stored as waveforms of one cycle or a half cycle of the fundamental wave component for each amplitude and phase of the voltage command.

9. The drive controller includes: The power conversion device according to claim 7 , wherein the second command candidates are stored as a function of the amplitude and phase of the voltage command.

10. The AC voltage is supplied to a load; the drive controller generates the first command based on at least one of a torque, a rotational speed, a position, an amplitude, a phase, and a frequency of a current of the rotating machine when the load is a rotating machine; 6. The power conversion device according to claim 1, wherein when the load is other than a rotating machine, the first command is generated based on at least one of an amplitude, a phase, and a frequency of a current of the load.

11. The AC voltage is supplied to a load; The drive controller includes: In comparison with a case where the power conversion device is operated by generating the gate signal by comparing the carrier signal with a sine wave modulated signal of the fundamental wave component of the first command, When the load is a rotating machine, the amplitude of a predetermined frequency component included in at least one parameter of the voltage, current, torque, loss, vibration, the DC voltage, and the DC current flowing on the DC side of the power conversion device is decreased or increased, When the load is other than a rotating machine, the amplitude of a predetermined frequency component included in at least one parameter of the voltage, current, loss of the load, the DC voltage, and the DC current flowing on the DC side of the power conversion device is decreased or increased. The power conversion device according to claim 1 , further comprising: a power supply means for supplying the second command to the power conversion device;

12. 6. The power conversion device according to claim 1, further comprising an inverter circuit in which a DC voltage is applied to both ends of the inverter circuit and in which a plurality of legs, each leg including two reverse-conducting semiconductor switching elements connected in series, are connected in parallel.

13. The power conversion device according to claim 1 , wherein the semiconductor switching elements are formed of a wide band gap semiconductor.