Motor control device

Abstract

In a motor with multiple winding systems having spatial phase differences in the circumferential direction between systems, the present invention provides a motor control device that enhances the torque ripple suppression effect. [Solution] The motor control device 400 controls the driving of multiple inverters 601, 602, which are provided corresponding to each winding set 801, 802, in a motor 80 with multiple winding sets 801, 802 having a spatial phase difference in the circumferential direction between the sets. Voltage command calculation units 411, 412 calculate voltage commands for each set that have an electrical angular phase difference between the sets corresponding to the spatial phase difference of the winding sets. Pulse voltage generation units 501, 502 generate pulse voltages that switch the switching elements of each phase constituting the inverter on and off based on the voltage commands for each set. The pulse voltage generation units 501, 502 include output voltage matching pulse generation units 511, 512 that generate pulse voltages so that the waveforms of the pulse voltages of each set match.

Description

[Technical Field]

[0001] This invention relates to a motor control device. [Background technology]

[0002] Conventionally, in a motor with multiple winding sets having a spatial phase difference in the circumferential direction between the sets, a motor control device is known that generates a pulse voltage to switch the switching elements of the inverters of each set on and off.

[0003] For example, the power converter disclosed in Patent Document 1 is a three-phase two-system motor in which two sets of windings are arranged with an electrical angle offset of 30 degrees from each other. It generates pulse voltages by comparing the voltage command of each system with a PWM reference signal (carrier wave). The voltage commands of the two systems are generated with a phase difference of 30 degrees from each other. The carrier waves of the two systems have the same frequency, but are generated with a phase difference of (1 / 4) period from each other. This ensures that when the amplitude of the duty cycle command is within a predetermined range, the discharge periods of the inverter's smoothing capacitors do not overlap between the systems, thereby suppressing current ripple flowing through the smoothing capacitors (see Figure 14). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5040799 [Overview of the project] [Problems that the invention aims to solve]

[0005] By shifting the phase of the voltage commands for two three-phase motor systems by an electrical angle of 30 degrees, the sixth-order torque ripple is almost canceled out when considering the fundamental wave. However, when comparing the pulse voltages that drive the inverters between the systems, the pulse voltages of the two systems do not perfectly match in the conventional technology described in Patent Document 1, which shifts the PWM reference signal by (1 / 4) period.

[0006] At low motor speeds, the carrier frequency per electrical cycle of the voltage command is relatively high, resulting in small differences in pulse voltage between systems. However, at high motor speeds, the carrier frequency per electrical cycle of the voltage command becomes relatively low, leading to larger differences in pulse voltage between systems. This results in differences in the harmonic content of the output voltage, particularly the sixth-order component, reducing the cancellation effect of the sixth-order torque ripple. Consequently, for example, in motors mounted in vehicles, there are concerns about deterioration of NV (noise, vibration) characteristics.

[0007] The present invention has been made in view of the above-mentioned problems, and its object is to provide a motor control device that enhances the torque ripple suppression effect in a motor with multiple winding sets having a spatial phase difference in the circumferential direction between the sets. [Means for solving the problem]

[0008] The motor control device of the present invention controls the drive of multiple inverters (601, 602) provided corresponding to each winding set (801, 802) in a motor (80) with multiple winding sets (801, 802) having a spatial phase difference in the circumferential direction between the sets. This motor control device comprises a voltage command calculation unit (411, 412) and a pulse voltage generation unit (501, 502).

[0009] The voltage command calculation unit calculates the voltage command for each system, which has an electrical angular phase difference between systems corresponding to the spatial phase difference of the winding assemblies.

[0010] The pulse voltage generation unit generates pulse voltages that switch the on / off state of the switching elements of each phase constituting the inverter based on the voltage commands of each system.

[0011] The pulse voltage generation unit includes output voltage matching pulse generation units (511, 512) that generate pulse voltages so that the waveforms of the pulse voltages of each system match.

[0012] In the present invention, by matching the waveforms of the pulse voltages of each system, the content ratios of the harmonic components of the output voltages of each system can be made highly uniform, and the effect of suppressing torque ripple can be maximized. In particular, in the case of a three-phase motor, the effect of suppressing the sixth-order torque ripple can be maximized.

Brief Description of the Drawings

[0013] [Figure 1] Schematic configuration diagram of a three-phase two-system motor and a motor control device. [Figure 2] Schematic diagram showing the spatial phase shift of the winding sets of two systems. [Figure 3] Block diagram showing the general configuration of the motor control device according to the first embodiment. [Figure 4] Block diagram of the output voltage matching pulse generation unit according to the first embodiment. [Figure 5] Block diagram of the capacitor ripple suppression pulse generation unit according to the first embodiment. [Figure 6] Block diagram showing the phase reference centralized configuration of the motor control device according to the first embodiment. [Figure 7] Waveform diagram showing the voltage commands, triangular waves, and line-to-line voltages of each system during the generation of the output voltage matching pulse according to the first embodiment. [Figure 8] Waveform diagram showing the voltage commands, triangular waves, and line-to-line voltages of each system during the generation of the capacitor ripple suppression pulse according to the first embodiment. [Figure 9] Diagram comparing the harmonic component content ratios of the output voltage during the generation of the output voltage matching pulse and during the generation of the capacitor ripple suppression pulse. [Figure 10] Diagram showing switching examples 1 and 2 between the output voltage matching pulse generation unit and the capacitor ripple suppression pulse generation unit. [Figure 11] Block diagram of the output voltage matching pulse generation unit according to the second embodiment. [Figure 12] Waveform diagram showing the voltage commands, triangular waves, and line-to-line voltages of each system during the generation of the output voltage matching pulse according to the second embodiment. [Figure 13] Block diagram of the output voltage matching pulse generation unit according to the third embodiment. [Figure 14] A diagram illustrating the effect of suppressing capacitor ripple. [Modes for carrying out the invention]

[0014] Multiple embodiments of the motor control device according to the present invention will be described with reference to the drawings. In multiple embodiments, substantially identical components are denoted by the same reference numerals, and redundant descriptions are omitted. The first to third embodiments are collectively referred to as "this embodiment." The motor control device of the present invention controls the drive of multiple inverters provided corresponding to each winding set in a motor with multiple winding sets having a circumferential spatial phase difference between the sets. In this embodiment, a motor control device applied to a three-phase two-set motor and controlling the drive of two inverters will be described.

[0015] [Outline configuration of a three-phase two-system motor and motor control device] Referring to Figures 1 and 2, the schematic configuration of the three-phase two-system motor and motor control device will be described. The motor 80 is a three-phase brushless motor in which two winding sets 801 and 802 have a spatial phase difference in the circumferential direction between the systems. The first winding set 801 consists of a U-phase winding 811, a V-phase winding 812, and a W-phase winding 813. The second winding set 802 consists of a U-phase winding 821, a V-phase winding 822, and a W-phase winding 823. Each phase winding 821, 822, and 823 of the second winding set 802 is positioned at a position shifted by an electrical angle of 30 degrees in the circumferential direction relative to each phase winding 811, 812, and 813 of the first winding set 801.

[0016] The first inverter 601 and the second inverter 602 are provided corresponding to the winding sets 801 and 802 of each system. Each inverter 601 and 602 has six switching elements 611-616 and 621-626, such as MOSFETs, bridged between a high-potential line Lp and a low-potential line Lg. Switching elements 611, 612, 613, 621, 622, and 623 are upper-arm switching elements for the U-phase, V-phase, and W-phase, respectively. Switching elements 614, 615, 616, 624, 625, and 626 are lower-arm switching elements for the U-phase, V-phase, and W-phase, respectively.

[0017] Current sensors 701 and 702, which detect the three-phase currents Iu1, Iv1, Iw1, Iu2, Iv2, and Iw2 of each system and output them to the motor control device 400, are provided, for example, on the low-potential side of the lower arm switching element. The three-phase currents of each system are converted into dq-axis currents by, for example, vector control and used for current feedback control.

[0018] DC voltage is supplied from the battery 33 to the inverters 601 and 602 of each system. For example, when applied to a motor 80 mounted on a vehicle, a battery of 12V to several hundred volts is used. The battery 33 is not limited to a configuration that is provided in common to both systems as shown in Figure 1, but may also be provided individually for each system.

[0019] A smoothing capacitor 34 is connected in parallel with the battery 33 to the input side of inverters 601 and 602. The smoothing capacitor 34 stores charge, assisting in the power supply from the battery 33 to inverters 601 and 602, and suppressing surge currents and inverter switching noise from flowing into the circuit. When the smoothing capacitors 34 connected to the two inverters 601 and 602 repeatedly charge and discharge in response to switching operations, a capacitor ripple current is generated. It is known that the capacitor ripple current when the discharge periods of the two systems overlap is larger than the capacitor ripple current when the charging periods overlap.

[0020] The motor control device 400 is configured as an ECU, primarily consisting of a microcontroller. Inside the motor control device 400 are a CPU, ROM, RAM, I / O (not shown in the diagram), and bus lines connecting these components. The motor control device 400 performs control through software processing by executing pre-stored programs on the CPU, and through hardware processing using dedicated electronic circuits.

[0021] The motor control device 400 acquires the three-phase currents Iu1, Iv1, Iw1, Iu2, Iv2, and Iw2 from the current sensors 701 and 702, and the motor rotation angle θ from the rotation angle sensor 85 provided on the motor 80. In addition, a torque command is input to the motor control device 400 from a higher-level control circuit (not shown). Based on this information, the motor control device 400 calculates a voltage command that has an electrical angular phase difference between the systems corresponding to the spatial phase difference of the winding assemblies 801 and 802. In other words, it calculates a voltage command with an electrical angular phase difference of 30 degrees between the systems.

[0022] The motor control device 400 also generates pulse voltages that switch the on and off of the switching elements 611-616 and 621-626 of each phase that make up inverters 601 and 602, and outputs them to inverters 601 and 602 of each system. In this way, the motor control device 400 controls the drive of the two systems of inverters 601 and 602.

[0023] The inverters 601 and 602 of each system switch according to the pulse voltage output by the motor control device 400, converting the DC voltage supplied from the battery 33 into three-phase voltages Vu1, Vv1, Vw1, Vu2, Vv2, and Vw2, and supplying them to the winding assemblies 801 and 802.

[0024] As shown in Figure 2, the two-system three-phase motor 80 is a double-winding rotating machine in which two sets of three-phase windings 801 and 802 are mounted coaxially. The two sets of three-phase windings 801 and 802 have equivalent electrical characteristics and are arranged on a common stator with a phase shift of 30 degrees [electrical angle]. When an unmodulated sinusoidal voltage is applied to each phase of the first and second systems, if the voltage amplitude is A, the three-phase voltages Vu1, Vv1, Vw1 of the first system and the three-phase voltages Vu2, Vv2, Vw2 of the second system are expressed by equations (1.1) to (1.3) and (2.1a) to (2.3a).

[0025] Vu1 = Asinθ ···(1.1) Vv1 = Asin(θ - 120) ... (1.2) Vw1 = Asin(θ - 240) ... (1.3) Vu² = Asin(θ + 30) ... (2.1a) Vv² = Asin(θ - 90) ... (2.2a) Vw2 = Asin(θ - 2¹⁰) ... (2.3a)

[0026] If the phase relationship between the two systems is reversed for the leading and lagging sides, for example, the phase of the second system's U-phase (θ+30) is replaced with (θ-30). In that case, the three-phase voltages Vu2, Vv2, and Vw2 of the second system are expressed by equations (2.1b) to (2.3b) instead of equations (2.1a) to (2.3a). Furthermore, generalizing by considering the symmetry of the U-phase, V-phase, and W-phase, a phase shift equivalent to 30 [deg] can be expressed as an electrical angle of (30 ± 60 × k) [deg] (where k is an integer).

[0027] Vu² = Asin(θ-30) ···(2.1b) Vv² = Asin(θ - 150) ... (2.2b) Vw² = Asin(θ - 270) ... (2.3b)

[0028] (First Embodiment) Next, with reference to Figures 3 to 6, the configuration of the motor control device 400 according to the first embodiment will be described. In the first embodiment, pulse voltages for driving inverters 601 and 602 are generated by a PWM method that compares a duty cycle command based on a voltage command with a carrier wave for each system. In this description, "carrier wave" will be referred to as a "triangular wave". In other embodiments, a sawtooth wave may be used as the carrier wave. In the first embodiment, pulse voltages are generated by a PWM method using triangular wave comparison for each system.

[0029] Referring to Figure 3, a general configuration of a motor control device 400 in which the phase reference of the triangular wave of each system can be arbitrarily set will be described. The motor control device 400 includes a voltage command calculation unit 411 and a pulse voltage generation unit 501 for the first system, and a voltage command calculation unit 412 and a pulse voltage generation unit 502 for the second system. As shown by the dashed lines, modulation processing units 421 and 422 may be provided after the voltage command calculation units 411 and 412 as appropriate.

[0030] The first voltage command calculation unit 411 calculates the first current command Idq * 1 and the actual current Idq1 are input, and a voltage command is calculated by current feedback control. Specifically, the voltage command calculation unit 411 calculates the dq axis voltage command, and further converts the dq axis voltage command into a two-phase to three-phase command Vuvw based on the rotation angle θ. * Output 1.

[0031] The modulation processing unit 421 performs modulation processing such as overmodulation and high-frequency superposition to improve voltage utilization, and the modulated three-phase voltage command Vuvw ** Output 1. Alternatively, as described later, modulation processing may be performed in the duty ratio calculation unit 551 within the pulse voltage generation unit 501. If the modulation processing unit 421 is not provided, the three-phase voltage command Vuvw output by the voltage command calculation unit 411 is output. * The value 1 is directly input to the pulse voltage generation unit 501.

[0032] The pulse voltage generation unit 501 generates the voltage command Vuvw **Based on 1, a pulse voltage Vpulse1 for switching on and off the switching elements 611 to 616 of each phase constituting the first system inverter 601 is generated.

[0033] Similarly, the voltage command calculation unit 412 of the second system receives the current command Idq of the second system * 2 and the actual current Idq2 as inputs, calculates a voltage command by current feedback control, and outputs a three-phase voltage command Vuvw * 2. The modulation processing unit 422 appropriately modulates the three-phase voltage command Vuvw * 2 and outputs the modulated three-phase voltage command Vuvw ** 2. The pulse voltage generation unit 502 generates a pulse voltage Vpulse2 for switching on and off the switching elements 621 to 626 of each phase constituting the second system inverter 602 based on the voltage command Vuvw ** 2.

[0034] Here, the voltage command calculation units 411 and 412 calculate the voltage command Vuvw of the first system * 1 and the three-phase voltage command Vuvw of the second system * 2 so as to have an electrical angle phase shift between systems corresponding to the spatial phase shift of the winding sets 801 and 802. As described above with reference to FIG. 2, the voltage commands Vuvw of each system are such that they have a phase shift of an electrical angle of 30 [deg], or in a general formula, an electrical angle of (30 ± 60 × k) [deg]. * 1, Vuvw * 2 are calculated.

[0035] The first system pulse voltage generation unit 501 includes an output voltage matching pulse generation unit 511, a capacitor ripple suppression pulse generation unit 521, and a switching unit 591. The second system pulse voltage generation unit 502 includes an output voltage matching pulse generation unit 512, a capacitor ripple suppression pulse generation unit 522, and a switching unit 592. In the figure, "capacitor ripple" is denoted as "C ripple". The same shall apply in the following figures. The first system pulse voltage generation unit 501 and the second system pulse voltage generation unit 502 communicate the information of the triangular wave phase with each other.

[0036] [[ID=३३]] The motor control device 400 also has a speed calculation unit 45 that calculates the rotational angular velocity ω by differentiating the rotational angle θ detected by the rotational angle sensor 85 with respect to time. The rotational angular velocity ω [rad / s] is converted to rotational speed by multiplying it by a proportionality constant, and is therefore referred to as "(motor) rotational speed ω" below.

[0037] The rotational speed ω calculated by the speed calculation unit 45 is input to the output voltage matching pulse generation units 511 and 512 of one or both systems. The dashed arrows indicate that, by setting a triangular wave phase reference, the input of the rotational speed ω can be omitted to, for example, the output voltage matching pulse generation unit 511 of the first system. Furthermore, as will be described later with reference to Figure 10, in an embodiment where the pulse voltage is switched based on the rotational speed ω, the rotational speed ω is input to the switching units 591 and 592.

[0038] Next, referring to Figures 4 and 5, the configurations of the output voltage matching pulse generation units 511 and 512 and the capacitor ripple suppression pulse generation units 521 and 522 in a general configuration will be described. The output voltage matching pulse generation units 511 and 512 and the capacitor ripple suppression pulse generation units 521 and 522 each share triangular wave phase information and function in cooperation with each other within the system.

[0039] In Figure 4, the collaborative function unit of the output voltage matching pulse generation unit spanning two systems is represented by the symbol "51". Furthermore, the pulse voltages Vpulse1 and Vpulse2 output by the output voltage matching pulse generation units 511 and 512 of each system are appended with "_F", the initial of "Fit". The output voltage matching pulse generation units 511 and 512 generate pulse voltages Vpulse1_F and Vpulse2_F so that the waveforms of the pulse voltages of each system match. An example of triangular wave comparison by the output voltage matching pulse generation units 511 and 512 is shown in Figure 7.

[0040] In Figure 5, the collaborative function unit of the capacitor ripple suppression pulse generation unit spanning two systems is represented by the symbol "52". Furthermore, the pulse voltages Vpulse1 and Vpulse2 output by the capacitor ripple suppression pulse generation units 521 and 522 of each system are denoted with "_C". An example of triangular wave comparison by the capacitor ripple suppression pulse generation units 521 and 522 is shown in Figure 8. Figure 8 has two aspects: a comparative example illustrating the effect of the output voltage matching pulse generation unit 51 in comparison with Figure 7, and an embodiment that is switched and implemented depending on the conditions.

[0041] As shown in Figure 4, the first output voltage matching pulse generation unit 511 includes a triangular wave generation unit 531, a duty cycle calculation unit 551, and a triangular wave comparison unit 561. The second output voltage matching pulse generation unit 512 includes a triangular wave generation unit 532, a duty cycle calculation unit 552, and a triangular wave comparison unit 562.

[0042] The triangular wave generation units 531 and 532 in each system generate triangular waves with the same frequency and constant regardless of the rotational speed ω. The output voltage matching pulse generation unit 51 shifts the phase of the triangular waves in each system in accordance with the electrical angular phase shift of the voltage command. Therefore, the triangular waves in each system are generated to have a phase shift of 30 degrees. For example, if the first system is used as the phase reference for the triangular waves, the phase of the triangular wave in the second system is adjusted to be shifted by an electrical angle of 30 degrees relative to the phase reference.

[0043] In this case, the second triangular wave generation unit 532 calculates the time to shift the phase of the triangular wave based on the rotational speed ω [rad / s] information. Since the time T360, which corresponds to one period of electrical angle (i.e., an electrical angle of 360 [deg]), is "T360 = 2π / ω", the corresponding time T30 for an electrical angle of 30 [deg] is calculated as "T30 = π / 6ω". Therefore, the second triangular wave generation unit 532 can generate a triangular wave with a phase shift of an electrical angle of 30 [deg] by shifting the time by (π / 6ω) relative to the reference timing of the triangular wave of the first system.

[0044] Alternatively, the phase of the triangular wave in the first system may be adjusted using the second system as the phase reference for the triangular wave. Or, the rotational speed ω may be input to the triangular wave generation units 531 and 532 of both systems, and the phase may be adjusted so that, for example, the triangular wave phase of the first system leads by 15 degrees and the triangular wave phase of the second system lags by 15 degrees relative to a phase reference set separately for each system.

[0045] Each system's duty cycle calculation unit 551, 552 calculates the three-phase voltage command Vuvw for the inverter input voltage. ** 1. Vuvw ** Based on the amplitude ratio of 2, a duty cycle is calculated with the negative peak voltage at 0%, the center voltage at 50%, and the positive peak voltage at 100%. Then, the duty cycle calculation units 551 and 552 receive the voltage command Vuvw ** 1. Vuvw ** The duty cycle commands Duvw1 and Duvw2, converted from 2 to duty cycles, are output to the triangular wave comparison units 561 and 562.

[0046] Furthermore, the duty ratio calculation units 551 and 552 may perform modulation processing, such as equalizing the maximum and minimum duty ratios, on the duty commands Duvw1 and Duvw2 converted from the voltage command. In this case, the duty ratio calculation units 551 and 552 are considered to also function as a modulation processing unit.

[0047] The triangular wave comparison units 561 and 562 in each system compare the duty cycle commands Duvw1 and Duvw2 with the triangular waves to generate pulse voltages Vpulse1_F and Vpulse2_F. The pulse voltages Vpulse1_F and Vpulse2_F generated in this way for each system have waveforms that are perfectly identical, as shown in Figure 7.

[0048] As shown in Figure 5, the configuration of the capacitor ripple suppression pulse generation unit 52 is the same as that of the output voltage matching pulse generation unit 51. The duty ratio calculation units 551, 552 and the triangular wave comparison units 561, 562 may be provided in common with the output voltage matching pulse generation unit 51. The triangular wave generation units 531, 532 of each system generate triangular waves with the same and constant frequency. However, in the capacitor ripple suppression pulse generation unit 52, the phase difference of the triangular waves between systems is different from that of the output voltage matching pulse generation unit 51.

[0049] In the capacitor ripple suppression pulse generation unit 52, the triangular waves of each system are generated with a phase shift of (1 / 4) period relative to the triangular wave, regardless of the rotational speed ω. For example, if the first system is used as the phase reference for the triangular wave, the phase of the triangular wave of the second system is adjusted to be shifted by (1 / 4) period relative to the phase reference.

[0050] Similar to the output voltage matching pulse generation unit 51, the capacitor ripple suppression pulse generation unit 52 may also use the second system as the phase reference for the triangular wave and adjust the phase of the triangular wave of the first system. Alternatively, the phases may be adjusted so that, for example, the triangular wave phase of the first system is shifted forward (1 / 8) period and the triangular wave phase of the second system is shifted backward (1 / 8) period with respect to a phase reference set separately from each system.

[0051] The triangular wave comparison units 561 and 562 in each system compare the duty cycle commands Duvw1 and Duvw2 with the triangular waves to generate pulse voltages Vpulse1_C and Vpulse2_C. As shown in Figure 8, the waveforms of the pulse voltages Vpulse1_C and Vpulse2_C generated in this way do not perfectly match.

[0052] Instead, it is conventionally known that if the phases of the two triangular waves are shifted by (1 / 4) period, the discharge periods of the smoothing capacitor 34 will not overlap between the systems, as long as the amplitude of the duty cycle command is within a predetermined range, as shown in Figure 14. In Figure 14, Du1, Dv1, and Dw1 represent the duty cycle commands for the U, V, and W phases of the first system, respectively, and Du2, Dv2, and Dw2 represent the duty cycle commands for the U, V, and W phases of the second system, respectively. The minimum and maximum values ​​of the duty cycle command are set to fall within approximately the range from the lower quarter to the upper quarter (duty cycle ratio of 25-75%). P1 and P2 represent the triangular waves of the first and second systems, respectively. The phase of the triangular wave P1 of the first system and the triangular wave P2 of the second system are shifted by (1 / 4) period. Because the discharge periods of the smoothing capacitor 34 do not overlap between the systems, current ripple flowing through the smoothing capacitor 34 can be suppressed, and heat generation can be reduced.

[0053] Here, even if the amplitude of the duty cycle command exceeds the above range and it is not possible to completely eliminate the overlap between discharge periods, if the overlap between systems can be reduced even slightly, the effective value of the ripple current and the average ripple current can be lowered. In other words, the capacitor ripple suppression pulse generation unit 52 can generate pulse voltages Vpulse1_C and Vpulse2_C so as to reduce the overlap between discharge periods of each system.

[0054] Next, let's elaborate on setting the phase reference for the triangular wave. As shown in Figures 4 and 5, the output voltage matching pulse generation unit 51 and the capacitor ripple suppression pulse generation unit 52 may both be set to use, for example, the phase of the triangular wave generated by the first triangular wave generation unit 531 as the reference, and the second triangular wave generation unit 532 may always adjust for the phase shift. Figure 6 shows the configuration of such a phase-reference-centralized motor control device 400. In the phase-reference-centralized type, the rotational speed ω information is input only to the pulse voltage generation unit 502 of one system (for example, the second system), and a switching unit 592 is provided to switch between the pulse voltages generated by the output voltage matching pulse generation unit 512 and the capacitor ripple suppression pulse generation unit 522. Therefore, the configuration of the pulse voltage generation unit 501 of the other system (for example, the first system) can be simplified.

[0055] In Figure 6, it appears superficially that the first pulse voltage generation unit 501 does not have an output voltage matching pulse generation unit 511 and a capacitor ripple suppression pulse generation unit 521. However, as explained above, the function of a phase reference for the second output voltage matching pulse generation unit 512 and capacitor ripple suppression pulse generation unit 522 is included within the first pulse voltage generation unit 501. Therefore, even though it is a phase reference-centralized type, conceptually, the first pulse voltage generation unit 501 is interpreted as having an output voltage matching pulse generation unit 511 and a capacitor ripple suppression pulse generation unit 521.

[0056] Next, Figures 7 and 8 show the waveforms of the voltage command, triangular wave, and line voltage for each system during output voltage matching pulse generation and capacitor ripple suppression pulse generation, respectively. The voltage command is expressed as a duty cycle command converted to a duty cycle of 0-100%, and the waveform of the voltage command for one phase (e.g., U-phase) is shown. Corresponding to the spatial phase shift of winding sets 801 and 802, the phases of the in-phase voltage commands of the first and second systems are shifted by an electrical angle of 30 degrees.

[0057] In the examples in Figures 7 and 8, the waveform of the voltage command is exemplified by a waveform obtained by cutting off the portions exceeding the upper limit (100% duty cycle) and lower limit (0% duty cycle) from an overmodulated sine wave. In addition, waveforms in which the 5th and 7th harmonics are superimposed on the fundamental wave, or waveforms of voltage commands that have undergone modulation processing such as maximum and minimum duty cycle equalization processing, may also be used.

[0058] This example shows a motor rotation speed where the frequency of the triangular wave is 5 for each electrical cycle of the voltage command. In this case, one cycle of the triangular wave corresponds to an electrical angle of 72 degrees. Hereafter, the lower left point of the triangular wave, i.e., the point where it rises from a duty cycle of 0%, will be called the origin of the triangular wave. In both Figure 7 and Figure 8, the origin of one triangular wave in the first system is an electrical angle of 0 degrees. The frequencies of the triangular waves in the first and second systems are the same.

[0059] In the capacitor ripple suppression pulse generation shown in Figure 8, the second triangular wave is generated with a phase shift of (1 / 4) period relative to the first triangular wave, so that the starting point of one triangular wave is an electrical angle of 18 degrees. In this configuration, the discharge period of the smoothing capacitor 34 does not overlap between systems, or the overlap of the discharge periods between systems is minimized, thereby suppressing the current ripple flowing through the smoothing capacitor 34 and contributing to reduced heat generation (see Figure 14). However, because the phase relationship between the voltage command and the triangular wave differs between systems, the output voltages (line voltages) between systems do not perfectly match.

[0060] In contrast, when generating output voltage matching pulses as shown in Figure 7, the second triangular wave is generated with an electrical angle shift of 30 degrees relative to the first triangular wave, so the starting point of each triangular wave is an electrical angle of 30 degrees. In other words, the phase of both the voltage command and the triangular wave are shifted by an electrical angle of 30 degrees between the systems. As a result, the output voltages (line voltages) obtained by triangular wave comparison perfectly match between the systems.

[0061] The upper panel of Figure 9 shows the harmonic component content of the output voltage when an output voltage matching pulse is generated, and the lower panel shows the harmonic component content when a capacitor ripple suppression pulse is generated. Specifically, the first-order component ratio of the first system is set to 1, and the content of the first-order, fifth-order, and seventh-order components of the first and second systems are compared. The fifth-order and seventh-order components contribute to the sixth-order component of torque ripple.

[0062] When generating capacitor ripple suppression pulses, the proportions of the first, fifth, and seventh order components in the first and second systems do not match. Therefore, the cancellation effect of sixth-order torque ripple between systems cannot be maximized. On the other hand, when generating output voltage matching pulses, the proportions of the first, fifth, and seventh order components in the first and second systems match. Therefore, the cancellation effect of sixth-order torque ripple between systems can be maximized. Thus, for example, the NV (noise, vibration) characteristics can be improved in motors mounted on vehicles.

[0063] As described above, from the viewpoint of suppressing sixth-order torque ripple of a three-phase motor, it is preferable that the pulse voltage generation units 501 and 502 generate pulse voltages Vpulse1_F and Vpulse2_F using output voltage matching pulse generation units 511 and 512 in principle.

[0064] However, depending on the motor's driving conditions, it may be better to generate pulse voltages Vpulse1_C and Vpulse2_C using the capacitor ripple suppression pulse generation units 521 and 522. Therefore, the pulse voltage generation units 501 and 502 of the first embodiment switch between generating pulse voltages Vpulse1_C and Vpulse2_C using the capacitor ripple suppression pulse generation units 521 and 522 and generating pulse voltages Vpulse1_F and Vpulse2_F using the output voltage matching pulse generation units 511 and 512, depending on predetermined conditions.

[0065] For example, at low motor speeds, the frequency of the voltage command decreases while the triangular wave frequency remains constant, resulting in a relatively higher triangular wave frequency per electrical cycle of the voltage command. Therefore, the phase difference between the voltage command and the triangular wave across systems is less likely to affect the pulse voltage. Thus, at low motor speeds, it is considered advantageous to prioritize suppressing capacitor ripple over suppressing sixth-order torque ripple.

[0066] In this case, as shown in Switching Example 1 of Figure 10, the pulse voltage generation units 501 and 502 switch the pulse voltage generation mode according to the motor rotation speed ω. That is, when the motor rotation speed ω is less than a predetermined rotation speed threshold ω_th, the pulse voltage generation units 501 and 502 generate pulse voltages Vpulse1_C and Vpulse2_C using the capacitor ripple suppression pulse generation units 521 and 522. Also, when the motor rotation speed ω is greater than or equal to the rotation speed threshold ω_th, the pulse voltage generation units 501 and 502 generate pulse voltages Vpulse1_F and Vpulse2_F using the output voltage matching pulse generation units 511 and 512. In Figures 3 and 6, the rotation speed ω is input to the switching units 591 and 592 (or the switching unit 592 of one system), which corresponds to this configuration.

[0067] Furthermore, as shown in the switching example 2 of Figure 10, the pulse voltage generation units 501 and 502 may switch the pulse voltage generation mode according to the load torque trq or the capacitor temperature Tc. That is, when the load torque trq is less than a predetermined torque threshold trq_th, or the capacitor temperature Tc is less than a predetermined temperature threshold Tc_th, the pulse voltage generation units 501 and 502 generate pulse voltages Vpulse1_F and Vpulse2_F using the output voltage matching pulse generation units 511 and 512. Also, when the load torque trq is greater than or equal to the torque threshold trq_th, or the capacitor temperature Tc is greater than or equal to a predetermined temperature threshold Tc_th, the pulse voltage generation units 501 and 502 generate pulse voltages Vpulse1_C and Vpulse2_C using the capacitor ripple suppression pulse generation units 521 and 522. This makes it possible to suppress the heat generation of the smoothing capacitor 34 and to miniaturize the smoothing capacitor 34 by reducing the required capacitor capacitance.

[0068] (Second Embodiment) Referring to Figures 11 and 12, the configuration of the output voltage matching pulse generation units 511 and 512 according to the second embodiment will be described. In the block diagram of Figure 11, the functions of the duty cycle calculation units 551 and 552 and the triangular wave comparison units 561 and 562 are the same as in the first embodiment. In the second embodiment, pulse voltages Vpulse1_F and Vpulse2_F are generated by a synchronous PWM method that synchronizes the frequency of the triangular wave with the motor rotation speed ω.

[0069] The triangular wave generation units 541 and 542 in each system synchronize the reference phase of the triangular wave and communicate with each other so that the phase difference is zero. The motor rotation speed ω is input to the triangular wave generation units 541 and 542 in each system, and a triangular wave is generated such that the frequency of the triangular wave per electrical angle period is a multiple of 12. That is, the triangular wave generation units 541 and 542 in each system each generate a triangular wave with a "synchronization number" of 12n (where n is a natural number). Alternatively, the output voltage matching pulse generation unit 51 may have a single triangular wave generation unit common to both systems, and the triangular wave generated in common may be output to the triangular wave comparison units 561 and 562 in each system.

[0070] Here, we will explain the case where the number of synchronizations is 12 (n=1). As shown in Figure 12, in the case of a number of synchronizations of 12, one period of the triangular wave coincides with an electrical angle of 30 degrees. Therefore, the phase relationship between the voltage command and the triangular wave is the same in the first and second systems, and the pulse voltages Vpulse1_F and Vpulse2_F of the first and second systems generated by triangular wave comparison always match. Thus, in the second embodiment, as in the first embodiment, the objective of suppressing sixth-order torque ripple is achieved.

[0071] (Third embodiment) Referring to Figure 13, the configuration of the output voltage matching pulse generation units 511 and 512 according to the third embodiment will be described. In the third embodiment, pulse voltages Vpulse1_F and Vpulse2_F are generated by a pulse pattern method instead of the PWM method. The pulse pattern method is used, for example, in an overmodulation control region or a square wave control region that exceeds the upper limit of the modulation rate of the PWM control region, and inverters 601 and 602 are driven by one of the pulse patterns selected from a plurality of pulse patterns stored in advance.

[0072] Each output voltage matching pulse generation unit 511, 512 has a storage unit 571, 572 that stores multiple pulse patterns, and a pulse pattern setting unit 581, 582 that selects a pulse pattern according to the voltage command based on the rotation angle θ and rotation speed ω. The pulse pattern setting units 581, 582 are input to the voltage command amplitudes Vr1, Vr2 and voltage command phases ψ1, ψ2 calculated, for example, by torque feedback control.

[0073] The pulse patterns stored in memory units 571 and 572 are generated, for example, by comparing a voltage command with a fixed-frequency triangular wave and may be stored in their original form, or they may be stored in a corrected form, for example, so that the pulse width falls within a predetermined range. For example, memory units 571 and 572 store multiple patterns of the triangular wave used to generate pulse patterns, including the case where the phase difference between systems is an electrical angle of 30 degrees.

[0074] When there is a need for sixth-order torque ripple suppression, the pulse pattern setting units 581 and 582 read out pulse patterns generated using triangular waves with an electrical angle of 30 degrees between systems from the storage units 571 and 572 and output them as pulse voltages Vpulse1_F and Vpulse2_F. As a result, the output voltage matching pulse generation units 511 and 512 function in the same manner as in the first embodiment.

[0075] (Other embodiments) (a) The pulse voltage generation unit may not include a capacitor ripple suppression pulse generation unit, but may include only an output voltage matching pulse generation unit. In this case, the number of motor systems is not limited to two, but may be three or more. For example, in a three-phase, three-system motor control device, sixth-order torque ripple can be canceled by shifting the phase of the voltage command of the second system by an electrical angle of 20 degrees and the phase of the voltage command of the third system by an electrical angle of 40 degrees relative to the voltage command of the first system.

[0076] (b) When upper two-phase modulation processing or lower two-phase modulation processing is performed for duty commands Duvw1 and Duvw2, the capacitor ripple suppression pulse generation units 521 and 522 may shift the triangular wave phase between systems by (1 / 2) period of the triangular wave.

[0077] (c) The switching units 591 and 592 are not limited to a configuration in which they select voltage pulses already generated on the output side of the output voltage matching pulse generation units 511 and 512 and the capacitor ripple suppression pulse generation units 521 and 522. Depending on the selection result of the switching units 591 and 592 provided on the input side of the output voltage matching pulse generation units 511 and 512 and the capacitor ripple suppression pulse generation units 521 and 522, only the pulse generation unit on the selected side may perform triangular wave comparison.

[0078] (d) Regarding the switching threshold between output voltage matching pulse generation and capacitor ripple suppression pulse generation shown in Figure 10, in order to prevent control hunting, a forward switching threshold and a reverse switching threshold may be set in two stages, and the switching may be performed by hysteresis.

[0079] The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit.

[0080] The control devices and methods described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control devices and methods described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control devices and methods described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0081] 400...motor control device, 411, 412...Voltage command calculation unit, 501, 502...Pulse voltage generation unit. 51 (511, 512) ... Output voltage matching pulse generation unit, 52 (521, 522) ... Capacitor ripple suppression pulse generation unit, 601, 602... Inverter, 80...Motor, 801, 802...Winding assemblies.

Claims

1. A motor control device for a motor (80) with multiple winding sets (801, 802) having a spatial phase difference in the circumferential direction between the sets, which controls the driving of multiple inverters (601, 602) provided corresponding to each winding set of each set, Voltage command calculation units (411, 412) that calculate voltage commands for each system having an electrical angular phase difference between systems corresponding to the spatial phase difference of the winding assembly, A pulse voltage generation unit (501, 502) generates pulse voltages that switch the on / off state of the switching elements of each phase constituting the inverter based on the voltage commands of each system, Equipped with, The pulse voltage generation unit is a motor control device that includes output voltage matching pulse generation units (511, 512) that generate pulse voltages so that the waveforms of the pulse voltages of each system match.

2. The pulse generation unit generates pulse voltages using a PWM method that compares a duty cycle command based on the voltage command with a carrier wave for each system. The motor control device according to claim 1, wherein the output voltage matching pulse generation unit shifts the phase of the carrier wave of each system in accordance with the electrical angular phase shift of the voltage command.

3. A motor control device applicable to two motor systems, The pulse voltage generation unit is The inverter further includes capacitor ripple suppression pulse generation units (521, 522) that generate pulse voltages by shifting the phase of the carrier waves of each system by a predetermined amount so that the overlap of the discharge periods of the smoothing capacitors (34) connected between the two inverter systems, which are connected between the power line (Lp) and the ground line (Lg), is reduced. The motor control device according to claim 2, which switches between generating a pulse voltage by the capacitor ripple suppression pulse generation unit and generating a pulse voltage by the output voltage matching pulse generation unit according to predetermined conditions.

4. The motor control device according to claim 3, wherein the pulse voltage generation unit generates a pulse voltage using the capacitor ripple suppression pulse generation unit when the motor rotation speed is less than a predetermined rotation speed threshold, and uses the output voltage matching pulse generation unit when the motor rotation speed is equal to or greater than the rotation speed threshold.

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