JP2017017918A - Control apparatus of rotating machine driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus of a rotating machine driving device, capable of improving robustness.SOLUTION: A converter rectifies a full-wave of an N-phase AC voltage. A capacitor supports a DC voltage which ripples at a rate twice N as large as a frequency of the N-phase AC voltage. An inverter converts the DC voltage into the AC voltage, and outputs the AC voltage to a rotating machine. A command correction part corrects a command value iq** related on an AC current flowing in the rotating machine and generates a post-correction command value iq*. A control signal generation part generates a control signal to the inverter on the basis of the post-correction command value iq*. On the basis of a rotation speed ω of a rotation coordination system rotating in accordance with a rotation of the rotating machine, a second axial current id in the rotation coordination system, and a power source phase θ of the N-phase AC voltage, the command correction part obtains a current waveform of a first axial current in the rotation coordination system for matching the magnitude of AC voltage, and performs a correction on the basis of the current waveform to the command value iq** so that the first axial current is periodically changed in the same period as the current waveform and the same phase.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a control device for a rotating machine drive device, and more particularly to a technique for converting a DC voltage pulsating according to a power supply frequency into an AC voltage.

  Patent Document 1 describes a rotating machine control device. The rotating machine control device includes a single-phase diode bridge rectifier circuit, a capacitor having a small electrostatic capacity, and a three-phase inverter. The diode bridge rectifier circuit rectifies the AC voltage from the single-phase AC power source. The capacitor is connected between the output terminals of the diode bridge rectifier circuit. Since the capacitance of this capacitor is small, its smoothing function is small. Therefore, the DC voltage supported by the capacitor pulsates at twice the frequency of the power supply frequency. The three-phase inverter converts this DC voltage into a three-phase AC voltage and outputs the three-phase AC voltage to the rotating machine.

  The three-phase inverter is controlled by a control microcomputer. The control microcomputer controls the current flowing through the rotating machine by controlling the three-phase inverter. In Patent Document 1, a dq axis rotating coordinate system synchronized with a rotor of a rotating machine is introduced, and current is controlled as follows. That is, the d-axis component (d-axis current) of the current is kept substantially constant, and the q-axis component (q-axis current) of the current is pulsated at twice the power supply frequency.

Japanese Patent No. 4718041

  In driving a rotating machine, it has been desired to improve the stability (robustness) of control against disturbance.

  Therefore, an object of the present application is to provide a control device for a rotating machine drive device that can improve robustness.

  A first aspect of the control device for a rotating machine drive device according to the present invention is a full-wave rectification of N (N is a natural number) phase AC voltage, and a first DC line (LH) and a second DC line (LL) And a converter (2) that outputs a rectified voltage between the first DC line and the second DC line, and a DC voltage (Vdc) that pulsates at 2N times the frequency of the N-phase AC voltage. And a capacitor (C1) that supports the converter, the DC voltage is converted into an AC voltage based on a control signal, the AC voltage is output to the rotating machine (4), and an inverter that sends an AC current to the rotating machine ( 3) a device (5) for controlling a rotary machine drive device, comprising: a command generation unit (511) for generating the command value of the alternating current; and generating a corrected command value by correcting the command value And a control signal generator (52) that generates the control signal based on the corrected command value. In a rotating coordinate system including one axis and a second axis and rotating in accordance with the rotation of the rotating machine, the first axis component and the second axis component of the alternating current are respectively expressed as a first axis current (iq) and a second axis When defined as a biaxial current (id), the command correction unit is based on the rotational speed (ω) of the rotating coordinate system, the second axis current, the power phase of the N-phase AC voltage, and the device constant of the rotating machine. Then, a current waveform of the first axis current for matching the magnitude of the AC voltage with the DC voltage is obtained, and the first axis current periodically varies in the same cycle and the same phase as the current waveform. In addition, correction based on the current waveform is performed on the command value.

  A second aspect of the control device for the rotating machine drive device according to the present invention is the control device for the rotary machine drive device according to the first aspect, wherein the command correction unit (512) is configured to control the magnitude of the AC voltage. Is corrected when the average value is greater than the minimum value of the DC voltage (Vdc).

  A third aspect of the control device for the rotating machine drive device according to the present invention is the control device for the rotary machine drive device according to the first or second aspect, wherein the command generator (511) A first axis current command value for the first axis current is generated as the command value, and the command correction unit (512) has a value that is not less than the minimum value of the current waveform and not more than the maximum value of the current waveform. The correction is performed by multiplying the first axis current command value by a normalized waveform (Wq) obtained by normalizing the current waveform.

  A fourth aspect of the control device for a rotating machine drive device according to the present invention is the control device for a rotary machine drive device according to the third aspect, wherein the command correction unit is normalized by an average value of the current waveform. To obtain the normalized waveform.

  According to the first aspect of the control device for a rotating machine drive device according to the present invention, even if any of the rotation speed, the second shaft current, and the DC voltage changes due to a disturbance or the like, a pulsation waveform corresponding to this changes. The command value is calculated and corrected based on the pulsation waveform. Therefore, robustness can be improved.

  According to the 2nd aspect of the control apparatus of the rotary machine drive device concerning this invention, a voltage utilization factor can be improved.

  According to the 3rd aspect of the control apparatus of the rotary machine drive device concerning this invention, responsiveness can be improved.

  According to the 4th aspect of the control apparatus of the rotary machine drive device concerning this invention, the average value of the command value before correction | amendment and the average value of the command value after correction | amendment become equal. Therefore, the responsiveness can be improved most.

It is a figure which shows roughly an example of a structure of a rotary machine drive device. It is a figure which shows an example of DC voltage roughly. It is a figure which shows an example of the internal structure of an inverter roughly. It is a figure which shows roughly an example of the magnitude | size of a DC voltage and an output AC voltage. It is a figure which shows an example of q-axis current roughly. It is a figure which shows an example of a normalized current waveform roughly. It is a figure which shows roughly an example of an internal structure of a control apparatus. It is a figure which shows roughly an example of d-axis current command value and q-axis current command value. It is a flowchart which shows an example of the operation | movement which produces | generates an electric current command value. It is a figure which shows an example of an internal structure of a command correction | amendment part roughly. It is a figure which shows roughly an example of various electric quantities by this control. It is a figure which shows an example of various electric quantities by comparative control roughly. It is a figure which shows roughly an example of the relationship between the maximum value of the magnitude | size of output AC voltage, and a rotational speed. It is a figure which shows roughly an example of the relationship between the maximum value of the magnitude | size of output alternating current, and a rotational speed. It is a figure which shows roughly an example of the relationship between electric power and a rotational speed. It is a figure which shows an example of the harmonic component of an input electric current. It is a figure which shows an example of q-axis current command value roughly. It is a figure which shows an example of a normalized current waveform roughly. It is a figure which shows an example of q-axis current command value roughly.

<Configuration of power converter>
FIG. 1 schematically shows an example of the configuration of a rotating machine drive device. The rotating machine drive device includes a converter 2, a capacitor C 1, and an inverter 3.

  The converter 2 performs full-wave rectification on the N (N is a natural number) phase AC voltage input from the AC power source 1 to convert it into a rectified voltage, and outputs the rectified voltage between the DC lines LH and LL. The converter 2 is a diode rectifier circuit, for example. The converter 2 is not limited to a diode rectifier circuit, and may be another AC-DC converter that converts an AC voltage into a DC voltage. For example, a thyristor bridge rectifier circuit or a PWM (Pulse-Width-Modulation) type AC-DC converter can be adopted as the converter 2.

  In the example of FIG. 1, a three-phase AC voltage is input to the converter 2. However, the number of phases of the AC voltage input to the converter 2, that is, the number of phases of the converter 2 is not limited to three phases, and may be set as appropriate.

  The capacitor C1 is provided between the DC lines LH and LL. The capacitor C1 is a film capacitor, for example. Such a capacitor C1 is less expensive than an electrolytic capacitor. On the other hand, the capacitance of the capacitor C1 is smaller than the capacitance of the electrolytic capacitor, and the capacitor C1 does not sufficiently smooth the DC voltage Vdc between the DC lines LH and LL. In other words, the capacitor C1 allows pulsation of the rectified voltage rectified by the converter 2. For example, if full-wave rectification is used, the DC voltage Vdc pulsates at a frequency 2N times the frequency of the N-phase AC voltage (hereinafter also referred to as the power supply frequency). In the illustration of FIG. 1, the converter 2 full-wave rectifies the three-phase AC voltage, so the DC voltage Vdc pulsates at a frequency six times the frequency of the three-phase AC voltage.

  FIG. 2 is a diagram schematically showing an example of the DC voltage Vdc. In the illustration of FIG. 2, the power supply phase θ of the N-phase AC voltage input to the converter 2 is adopted on the horizontal axis, and the DC voltage Vdc is adopted on the vertical axis. In the example of FIG. 2, the DC voltage Vdc is normalized by the maximum value. As shown in FIG. 2, the DC voltage Vdc pulsates at a frequency six times the power supply frequency.

  As illustrated in FIG. 1, a reactor L <b> 1 may be provided on the DC link (DC lines LH and LL). Reactor L1 forms an LC filter together with capacitor C1. For example, the reactor L1 is provided on the DC line LH or the DC line LL (on the DC line LH in the illustration of FIG. 1) on the converter 2 side than the capacitor C1. Such an LC filter reduces, for example, current harmonics caused by switching of the inverter 3.

  The inverter 3 receives a DC voltage Vdc between the DC lines LH and LL (in other words, a DC voltage supported by the capacitor C1). Inverter 3 operates based on control signal S from control device 5 to convert this DC voltage Vdc into an AC voltage. The inverter 3 outputs the AC voltage to the rotating machine (for example, an electric motor) 4 and causes the AC currents iu, iv, and iw to flow to the rotating machine 4. Below, the alternating voltage and alternating current which the inverter 3 outputs are also called output alternating voltage and output alternating current, respectively. Here, the term “rotating machine” is adopted because the motor shows the behavior of the generator in the regenerative operation. The rotating machine 4 may be a synchronous machine or an induction machine.

  FIG. 3 schematically shows an example of the internal configuration of the inverter 3. For example, the inverter 3 includes a pair of switching units connected in series between the DC lines LH and LL for three phases. In the illustration of FIG. 3, a pair of switching units Sup and Sun are connected in series, a pair of switching units Svp and Svn are connected in series, and a pair of switching units Swp and Swn are connected in series. A connection point between a pair of switching units Sxp, Sxn (x represents u, v, w, and so on) of each phase is connected to the rotating machine 4 via the output line Px. When these switching units Sxp and Sxn are turned on / off based on an appropriate control signal S, the inverter 3 converts the DC voltage Vdc into an AC voltage and outputs it to the rotating machine 4.

  The rotating machine 4 is exemplified by a three-phase rotating machine, but the number of phases is not limited to this. In other words, the inverter 3 is not limited to a three-phase inverter.

  The rotating machine 4 includes a field 41 and an armature 42. The field 41 supplies interlinkage magnetic flux to the armature 42. For example, the field 41 has a permanent magnet, and an interlinkage magnetic flux is supplied by this permanent magnet. The armature 42 has an armature winding, and an alternating current from the inverter 3 flows through the armature winding. As a result, the armature 42 applies a rotating magnetic field to the field 41. The field 41 rotates relative to the armature 42 according to the rotating magnetic field.

<Overview of inverter control>
The inverter 3 in FIG. 3 cannot output an output AC voltage larger than the DC voltage Vdc. That is, an output AC voltage exceeding the DC voltage Vdc in FIG. 2 cannot be output. Therefore, when the control for outputting the output AC voltage with a substantially constant magnitude (corresponding to the amplitude) Vm is employed as in the prior art, the maximum value of the magnitude Vm is the minimum value of the DC voltage Vdc. In other words, the magnitude Vm is limited to the minimum value of the DC voltage Vdc. In the illustration of FIG. 2, a substantially constant magnitude Vm is also shown, which is smaller than the minimum value of the DC voltage Vdc.

  This point will be described in terms of the voltage utilization factor (= magnitude Vm / DC voltage Vdc). The voltage utilization rate is a value indicating how much the DC voltage Vdc is utilized. In the control for maintaining the magnitude Vm substantially constant as described above, the magnitude Vm is the minimum value of the DC voltage Vdc at the maximum. Therefore, in this control, the maximum value of the voltage utilization rate is smaller than 1.

  This voltage utilization factor is not always required to be high. For example, there are cases where the magnitude Vm of the output AC voltage may be small due to the low angular velocity (hereinafter referred to as “rotational speed”) ω of the electrical angle when the rotating machine 4 rotates. In this case, the voltage utilization rate is low.

  However, it is preferable that the maximum value of the voltage utilization rate is high. This is because a high maximum value of the voltage utilization rate means that a higher output AC voltage can be output, and thus the rotating machine 4 can be rotated at a higher rotational speed ω.

  Therefore, control that increases the maximum value of the voltage utilization rate, in other words, control that can output an output AC voltage larger than the minimum value of the DC voltage Vdc is adopted. In this control, the output AC voltage larger than the minimum value of the DC voltage Vdc is output by pulsating the magnitude Vm according to the pulsation of the DC voltage Vdc. FIG. 4 schematically shows an example of a waveform having a magnitude Vm that pulsates at substantially the same frequency and phase as the DC voltage Vdc. In the illustration of FIG. 4, the maximum value of the magnitude Vm is higher than the minimum value of the DC voltage Vdc, and the average value of the magnitude Vm is higher than the minimum value of the DC voltage Vdc. Therefore, the voltage utilization rate can be improved.

  In order to output the output AC voltage with such a periodically varying magnitude Vm, first, the output AC current flowing through the rotating machine 4 will be considered. This is because, in the present embodiment, as described later, it is intended to output the above-described output AC voltage by controlling the output AC current.

  First, a rotating coordinate system is introduced. The rotating coordinate system has a first axis and a second axis that are different from each other, and rotates according to the rotation of the rotating machine 4. For example, the first axis may be set in phase with the interlinkage magnetic flux from the field 41 to the armature 42. This first axis is also called the d-axis. Since the d-axis is along the interlinkage magnetic flux by the field 41, the rotating coordinate system rotates in synchronization with the rotating machine 4. As the second axis, an electrical angle that is orthogonal to the first axis can be employed. When the d-axis is adopted as the first axis, the second axis is also called the q-axis. This rotational coordinate system is also called a dq axis rotational coordinate system.

  Below, it demonstrates using a dq axis | shaft rotation coordinate system as an example. Hereinafter, the d-axis component and the q-axis component of the output AC voltage output to the rotating machine 4 are referred to as the d-axis voltage Vd and the q-axis voltage Vq, respectively, and the d-axis component and q of the output AC current flowing through the rotating machine 4 The axial components are called d-axis current id and q-axis current iq, respectively.

  In the range where the power supply phase θ is larger than −π / 6 and smaller than π / 6, the DC voltage Vdc is expressed by the following equation (see also FIG. 2).

  Vdc = √2 · Vs · cos θ (1).

  Here, Vs is an effective value of the amplitude of the N-phase AC voltage output from the AC power supply 1 (the amplitude of the line voltage). For example, the amplitude Vs may be set in advance and stored in a storage unit or the like, or may be detected. The power phase θ is detected by the power phase detector 8 (FIG. 1). The power phase detector 8 detects, for example, a zero cross of the N-phase AC voltage, and calculates the power phase θ based on the elapsed time from the detection timing.

  On the other hand, the magnitude Vm of the output AC voltage output from the inverter 3 is expressed by the following equation.

  Vm = √2 · √ (Vd ^ 2 + Vq ^ 2) (2).

  Here, X ^ Y represents a power with the base X and the exponent Y.

  In view of the voltage equation of the rotating machine 4, in a steady state, the d-axis voltage Vd and the q-axis voltage Vq are expressed by the following equations.

Vd = Ra · iq + ω · Ld · id + ω · φa (3)
Vq = Ra · id−ω · Lq · iq (4).

  Here, Ra is the resistance component of the armature winding of the armature 42, Ld and Lq are the d-axis inductance and q-axis inductance of the armature winding, respectively, and φa is applied to the armature 42 by the field 41. The flux linkage. These resistance component Ra, d-axis inductance Ld, q-axis inductance Lq, and linkage flux φa are device constants of the rotating machine 4, and may be preset and stored in a storage unit or the like, for example. Also good.

  As an example of a situation where the magnitude Vm pulsates at substantially the same frequency and the same phase as the DC voltage Vdc, consider a situation where the magnitude Vm and the DC voltage Vdc match. That is, consider a situation where Vdc = Vm. At this time, {right side of equation (1) = right side of equation (2)} holds. By substituting Equation (3) and Equation (4) into this equation and arranging the q-axis current iq, the following equation is derived.

  {Ra ^ 2 + (ω ・ Lq) ^ 2} ・ iq ^ 2 + 2 ・ Ra ・ ω ・ (Ld ・ id + φa-id ・ Lq) ・ iq + (ω ・ Ld ・ id) ^ 2 + (ω ・ φa ) ^ 2 + 2 ・ ω ^ 2 ・ Ld ・ id ・ φa ＋ (Ra ・ id) ^ 2-Vs ^ 2 ・ {cos (θ)} ^ 2 = 0 (5).

  When the q-axis current iq is obtained based on the equation (5) while paying attention to the fact that the q-axis current iq is positive, the following equation is derived.

  iq = {− b + √ (b ^ 2−a · c)} / a (6).

  Here, a, b, and c represent the coefficient of the square of the q-axis current iq, the coefficient of the q-axis current iq, and the constant term, respectively, in Expression (5).

  As illustrated in FIG. 5, the q-axis current iq also pulsates at a frequency 2N times the frequency of the N (here, 3) phase AC voltage.

  If the inverter 3 is controlled so that the q-axis current iq takes the current waveform represented by the equation (6), the magnitude Vm of the output AC voltage coincides with the DC voltage Vdc, so that the voltage utilization rate is the maximum value (= 1). That is, the current waveform represented by the equation (6) is a waveform for making the magnitude Vm of the output AC voltage coincide with the DC voltage Vdc.

  Such control can be realized by introducing a command value for the output alternating current flowing through the rotating machine 4. For example, a d-axis current command value id * and a q-axis current command value iq * are introduced. If the equation (6) is adopted as the q-axis current command value iq *, the q-axis current iq is controlled to take the current waveform represented by the equation (6).

  However, as described above, the voltage utilization factor does not always have to be 1, and in short, it is only necessary to output the output AC voltage with a magnitude Vm exceeding the minimum value of the DC voltage Vdc. For this purpose, the magnitude Vm does not need to coincide with the DC voltage Vdc, and as shown in FIG. 4, it may be pulsated at substantially the same frequency and phase as the DC voltage Vdc.

  (I) Conventionally, in a steady state, the q-axis current iq is controlled to be substantially constant, and an output AC voltage having a substantially constant magnitude Vm is output. (Ii) As described above, the q-axis current iq is If Equation (6) is adopted, considering that the magnitude Vm matches the DC voltage Vdc, if the q-axis current iq is pulsated with substantially the same frequency and substantially the same phase as the current waveform of Equation (6), The magnitude Vm can also be pulsated at substantially the same frequency and phase as the DC voltage Vdc.

  Therefore, in the present embodiment, the correction based on the current waveform is corrected so that the q-axis current iq pulsates with substantially the same frequency and the same phase as the current waveform of Equation (6). This is done for iq **. The q-axis current command value iq ** before correction is a command value determined according to the load of the rotating machine 4, and is ideally substantially constant in a steady state. The q-axis current command value iq ** will be described in detail later.

  First, a normalized waveform obtained by normalizing the current waveform of Equation (6) is obtained. Here, as an example, the current waveform is normalized with the maximum value Iq_p of the q-axis current iq. In view of Expression (6), when the value indicated by (a · c) is minimum, the q-axis current iq takes the maximum value Iq_p. That is, when the power supply phase θ is 0 degree, the q-axis current iq takes the maximum value Iq_p. Therefore, this maximum value iq_p is expressed by the following equation.

  iq_p = {− b + √ (b ^ 2−a · c ′)} / a (7).

  Here, c ′ is c when the power supply phase θ is 0 degree, and is specifically expressed by the following equation.

  c ’= (ω ・ Ld ・ id) ^ 2 + (ω ・ φa) ^ 2 + 2 ・ ω ^ 2 ・ Ld ・ id ・ φa + (Ra ・ id) ^ 2-Vs ^ 2 (8).

  The normalized waveform Wq is expressed by the following formula.

Wq = iq / iq_p
= {-B + √ (b ^ 2−a · c)} / {− b + √ (b ^ 2−a · c ′)} (9).

  FIG. 6 is a diagram schematically showing an example of the normalized waveform Wq. In this example, the maximum value of the normalized waveform Wq is 1. The normalized waveform Wq is multiplied by the q-axis current command value iq ** before correction to generate a corrected q-axis current command value iq *. The q-axis current command value iq * is expressed by the following equation.

  iq * = Wq · iq ** (10).

  By adopting this q-axis current command value iq *, the q-axis current iq can be pulsated with substantially the same frequency and substantially the same phase as the current waveform (FIG. 5). As a result, the magnitude Vm can be pulsated at substantially the same frequency and the same phase as the DC voltage Vdc (FIG. 4). Therefore, the maximum value of the voltage utilization rate can be improved.

  Moreover, the normalized waveform Wq includes the power supply phase θ, the rotational speed ω of the rotating machine 4 and the d-axis current id as variables. Therefore, even if a disturbance or the like that fluctuates these occurs, a normalized waveform Wq corresponding to the disturbance is generated. Therefore, robustness against disturbance can be improved.

  In actual control, not only the q-axis current command value iq * but also the d-axis current command value id * is calculated. Based on these d-axis current command value id * and q-axis current command value iq *, the inverter 3 To control. Below, the specific example of the control apparatus 5 which performs such control is demonstrated.

<Details of control device>
Referring to FIG. 1, control device 5 outputs control signal S to inverter 3. FIG. 7 is a diagram schematically illustrating an example of the internal configuration of the control device 5.

  The control device 5 includes a current command generation unit 51, a control signal generation unit 52, and a current phase command generation unit 53.

  Here, the control device 5 includes a microcomputer and a storage device. The microcomputer executes each processing step (in other words, a procedure) described in the program. The storage device is composed of one or more of various storage devices such as a ROM (Read Only Memory), a RAM (Random Access Memory), a rewritable nonvolatile memory (EPROM (Erasable Programmable ROM), etc.), and a hard disk device, for example. Is possible. The storage device stores various information, data, and the like, stores a program executed by the microcomputer, and provides a work area for executing the program.

  It can be understood that the microcomputer functions as various means corresponding to each processing step described in the program, or can realize that various functions corresponding to each processing step are realized. The control device 5 is not limited to this, and various procedures executed by the control device 5 or various means or various functions realized may be realized by hardware.

  The current command generator 51 generates a current command value for the output alternating current flowing through the rotating machine 4. Here, the d-axis current command value id * and the q-axis current command value iq * are generated and output to the control signal generation unit 52.

  The current command generation unit 51 includes a pre-correction command generation unit 511 and a command correction unit 512. The pre-correction command generation unit 511 generates a current command value before correction of the output alternating current flowing through the rotating machine 4. For example, a q-axis current command value iq ** for the q-axis current iq is generated. In the illustration of FIG. 7, the pre-correction command generation unit 511 includes a speed command generation unit 51a, a deviation calculation unit 51b, and a proportional integration control unit 51c.

  The speed command generation unit 51 a generates a rotation speed command value ω * for the rotation speed ω of the rotating machine 4. For example, the speed command generation unit 51a receives the rotational speed command value ω ** before correction, the current phase command value β *, and at least one of the d-axis current id and the q-axis current iq. The current phase command value β * is a command value for the current phase β, and the current phase β is the phase of the output alternating current in the dq axis rotation coordinate system (for example, the phase with respect to the q axis).

  The speed command generation unit 51a performs a correction using the current phase command value β * and at least one of the d-axis current id and the q-axis current iq on the rotation speed command value ω **, so that the rotation speed A command value ω * is generated. The rotation speed command value ω ** is given from, for example, an external CPU, and the current phase command value β * is given from the current phase command generation unit 53.

  The d-axis current id and the q-axis current iq are output from the three-phase / two-phase coordinate conversion unit 542. The three-phase / two-phase coordinate conversion unit 542 is provided in the control device 5, for example. The three-phase / two-phase converter 542 receives the output alternating currents iu, iv, iw flowing through the rotating machine 4 and the rotational speed ω of the rotating machine 4. The three-phase / two-phase coordinate conversion unit 5 performs coordinate conversion on the output currents iu, iv, iw based on the rotational speed ω, and calculates the d-axis current id and the q-axis current iq.

  The output alternating currents iu, iv, iw are detected based on, for example, the direct current Idc. In the illustration of FIG. 1, the current detection unit 6 detects a DC current Idc flowing through the DC link on the inverter 3 side of the capacitor C1. For example, the current detection unit 6 is provided on the DC line LL on the inverter 3 side of the capacitor C1. The direct current Idc and the control signal S to the inverter 3 are input to the three-phase detector 541. The three-phase detection unit 541 is provided in the control device 5, for example. The three-phase detection unit 541 associates the direct current Idc with one of the output alternating currents iu, iv, iw flowing through the rotating machine 4 based on the switching pattern of the inverter 3. That is, the DC current Idc is detected as one of the AC currents iu, iv, iw. Since the switching pattern changes with time, the alternating currents iu, iv, and iw can be detected based on the direct current Idc. In view of the fact that the sum of the alternating currents iu, iv, and iw is ideally zero, the remaining one-phase alternating current may be calculated from the two-phase alternating current. Such current detection is also called one-shunt current detection.

  The rotational speed command value ω * and the rotational speed ω are input to the deviation calculating unit 51b. The rotational speed ω of the rotating machine 4 is detected by, for example, a rotational speed detection unit (not shown). The rotation speed ω may be calculated by a known method based on the alternating currents iu, iv, iw. In this case, the rotational speed ω is not input to the control device 5. The deviation calculating unit 51b generates a deviation Δω by subtracting the rotational speed ω from the rotational speed command value ω *, and outputs this to the proportional-plus-integral control unit 51c.

  The proportional-integral control unit 51c performs proportional-integral control on the deviation Δω to generate a q-axis current command value iq ** before correction. The proportional-integral control unit 51c may determine the gain of at least one of proportional control and integral control based on at least one of the d-axis current command value id * and the q-axis current command value iq *. .

  In the illustration of FIG. 7, since proportional integral control is performed with respect to the deviation Δω of the rotational speed ω, the output of the proportional integral control unit 51c can be regarded as a torque command value.

  The command correction unit 512 calculates a current waveform of the q-axis current iq for making the magnitude Vm and the DC voltage Vdc coincide with each other based on, for example, the rotational speed ω, the d-axis current id, and the power supply phase θ. Based on this current waveform, the current command value before correction (here, the q-axis current command value iq **) is corrected, and the corrected command value (here, the q-axis current command value iq *). Is generated. Specifically, the q-axis current command value iq ** is multiplied by the normalized waveform Wq to generate the q-axis current command value iq *. In the example of FIG. 7, the generated q-axis current command value iq * is input to the limiter 514.

  In the example of FIG. 7, the current command generation unit 51 is also provided with a d-axis current command generation unit 513. For example, the maximum value iq * _p of the q-axis current command value iq * is input from the command correction unit 512 to the d-axis current command generation unit 513. As shown in FIG. 6, the normalized waveform Wq represented by equation (9) takes 1 as its maximum value, and therefore the maximum value iq * _p of the q-axis current command value iq * is q before correction. It matches the shaft current command value iq **. Therefore, in this example, the command correction unit 512 may output the q-axis current command value iq ** as the maximum value iq * _p.

  The d-axis current command generation unit 513 also receives the current phase command value β * from the current phase command generation unit 53. The d-axis current command generation unit 513 generates a d-axis current command value id * using the following formula, for example.

  id * = − iq * _p · tan β * (11).

  FIG. 8 is a diagram illustrating an example of the d-axis current command value id * and the q-axis current command value iq *. The q-axis current command value iq * periodically varies at substantially the same frequency and substantially the same phase as the current waveform (FIG. 5). The d-axis current command value id * takes a substantially constant value in a steady state. In calculating the d-axis current command value Id *, the maximum value iq * _p is not necessarily employed. For example, in equation (11), an average value or a minimum value of the q-axis current command value iq * may be employed instead of the maximum value iq * _p.

  In the illustration of FIG. 7, the current command generator 51 is also provided with a limiter 514. The limiter 514 receives the d-axis current command value id * from the d-axis current command generation unit 513 and receives the q-axis current command value iq * from the command correction unit 512. When the d-axis current command value id * and the q-axis current command value iq * are each greater than the upper limit value, the limiter 514 restricts each to the upper limit value and outputs it to the control signal generation unit 52. Note that the limiter 514 may not be provided.

  FIG. 9 is a flowchart showing an example of the operation of the current command generator 51. In the example of FIG. 9, in step ST1, the command correction unit 512 includes a power supply phase θ, a current phase command value β *, a rotational speed ω (or rotational speed command value ω *), and a q axis before correction. The current command value iq ** and the device constants of the rotating machine 4 (resistance component Ra, d-axis inductance Ld, q-axis inductance Lq, and linkage flux φa) are input.

  In the example of Expression (11), the d-axis current command value id * can be represented by (−iq ** · tan β *). Therefore, the d-axis current id used for calculation of the normalized waveform Wq can be substituted with (−iq ** · tan β *). Therefore, the q-axis current command value iq * can be calculated using the equation (10) based on the above-described parameters. In step ST2, command correction unit 512 generates q-axis current command value iq * using equation (10).

  Next, in step ST3, the d-axis current command generation unit 513 generates a d-axis current command value id * using Expression (11).

  The control signal generator 52 generates the control signal S based on the d-axis current command value id * and the q-axis current command value iq *. More specifically, the control signal S is generated so that the d-axis current id and the q-axis current iq approach the d-axis current command value id * and the q-axis current command value iq *, respectively.

  For example, the control signal generation unit 52 includes a voltage command generation unit 521, a magnitude phase calculation unit 522, a modulation factor calculation unit 523, and a switching modulation unit 524.

  The voltage command generation unit 521 generates a d-axis voltage command value Vd * and a q-axis voltage command value Vq * based on the d-axis current command value id * and the q-axis current command value iq *. The d-axis voltage command value Vd * and the q-axis voltage command value Vq * are command values for the d-axis voltage Vd and the q-axis voltage Vq, respectively.

  The voltage command generation unit 521 includes, for example, deviation generation units 52a and 52b, proportional integration control units 52c and 52d, calculation units 52e to 52h, and a limiter 52i. The limiter 52i receives the detected d-axis current id and q-axis current iq. When the d-axis current id and the q-axis current iq exceed the upper limit value, the limiter 52i limits the value to the upper limit value and outputs it.

  The deviation generator 52a receives the d-axis current command value id * and the d-axis current id. The deviation generator 52a subtracts the d-axis current id from the d-axis current command value id *, and outputs the deviation Δid to the proportional-integral controller 52c.

  The q-axis current command value iq * and the q-axis current iq are input to the deviation generation unit 52b. Deviation generation unit 52b subtracts q-axis current iq from q-axis current command value iq * and outputs deviation Δiq to proportional-integral control unit 52d.

  The proportional-integral control unit 52c performs proportional-integral control on the deviation Δid and outputs the result to the calculation unit 52g.

  The proportional-integral control unit 52d performs proportional-integral control on the deviation Δiq and outputs the result to the calculation unit 52h.

  The q-axis current iq, the rotation speed command value ω * of the rotating machine 4, and the q-axis inductance Lq are input to the calculation unit 52e. The computing unit 52e outputs the product (ω * · Lq · iq) of the rotational speed command value ω *, the q-axis inductance Lq, and the q-axis current iq to the computing unit 52g.

  The calculation unit 52g subtracts the output of the calculation unit 52e from the output of the proportional integration control unit 52c, and outputs the result to the magnitude phase calculation unit 522 as a d-axis voltage command value Vd *.

  The calculation unit 52f receives the d-axis current id, the rotational speed command value ω *, the d-axis inductance Ld, and the linkage flux φa. The calculation unit 52f adds the product of the rotational speed command value ω *, the d-axis inductance Ld, and the d-axis current id, and the product of the flux linkage φa and the rotational speed command value ω *, and the result (ω * · Ld · id + φa · ω *) is output to the calculation unit 52h.

  The calculation unit 52h adds the output of the proportional integration control unit 52d and the output of the calculation unit 52f, and outputs the result to the magnitude phase calculation unit 522 as the q-axis voltage command value Vq *.

  Based on the d-axis voltage command value Vd * and the q-axis voltage command value Vq *, the magnitude phase calculation unit 522 calculates the magnitude Vm of the output AC voltage and the voltage phase in the dq-axis rotational coordinate system. The magnitude Vm is calculated based on the formula (2). The voltage phase is calculated, for example, as an arctangent value obtained by dividing the d-axis voltage command value Vd * by the q-axis voltage command value Vq *. The magnitude Vm is output to the modulation factor calculator 523, and the voltage phase is output to the switching modulator 524.

  The modulation factor calculator 523 also receives the DC voltage Vdc supported by the capacitor C1. The DC voltage Vdc is detected by the voltage detector 7 with reference to FIG. Modulation rate calculation unit 523 calculates amplitude modulation rate k by dividing DC voltage Vdc from magnitude Vm, and outputs this amplitude modulation rate k to switching modulation unit 524. Note that the amplitude modulation rate k and the voltage utilization rate are the same in the equation.

  Switching modulation section 524 generates control signal S for controlling inverter 3 based on amplitude modulation factor k and voltage phase, and outputs this control signal S to inverter 3. For example, a three-phase voltage command value is generated based on the amplitude modulation factor k and the voltage phase, and the control signal S is generated based on a comparison between the three-phase voltage command value and a triangular wave. The inverter 3 converts the DC voltage Vdc into a desired AC voltage based on the control signal S, and outputs this to the rotating machine 4.

  The current phase command generator 53 receives the DC voltage Vdc and the magnitude Vm. The current phase command generation unit 53 generates a current phase command value β * based on the DC voltage Vdc and the magnitude Vm. For example, the current phase command generation unit 53 includes a peak extraction unit 531, a division unit 532, a subtraction unit 534, a proportional limit unit 535, a proportional integration control unit 536, and a proportional limit unit 537.

  The peak extraction unit 531 detects the maximum value Vdc_p of the DC voltage Vdc and outputs it to the division unit 532.

  Division unit 532 divides maximum value Vdc_p of DC voltage Vdc from magnitude Vm, and outputs the result (Vm / Vdc_p) to subtraction unit 534.

  Subtracting unit 534 subtracts 1 from the output of dividing unit 532 and outputs the result (Vm / Vdc_p−1) to proportional limiting unit 535.

  The proportional restriction unit 535 multiplies the output of the subtraction unit 534 by a gain. When the result exceeds the upper limit value, the output is limited to the upper limit value. When the result is lower than the lower limit value, the output is limited to the lower limit value. Proportional limiting unit 535 may limit the upper limit value and the lower limit value without multiplying the gain.

  The proportional-integral control unit 536 performs proportional-integral control on the output of the proportional limiter 535 and outputs the result.

  The proportional restriction unit 537 multiplies the output of the proportional integration control unit 536 by a gain. When the result exceeds the upper limit value, the output is limited to the upper limit value. When the result is lower than the lower limit value, the output is limited to the lower limit value. Proportional limiting unit 537 outputs the result as current phase command value β *. Note that the proportional limiter 537 may limit the upper limit value and the lower limit value without multiplying the gain.

  By the way, the current phase command generation unit 53 may increase the current phase command value β * in order to perform the flux-weakening control in a state where the magnitude Vm is close to the upper limit value (DC voltage Vdc). Thereby, the current phase β can be advanced and the d-axis current id can be increased. Therefore, the total magnetic flux (φa−Ld · id) can be reduced, and an increase in induced voltage can be suppressed by reducing the total magnetic flux. Therefore, the rotational speed ω can be further increased. That is, when the magnitude Vm is increased with the increase in the rotational speed ω, when the magnitude Vm is close to the upper limit value, the rotational speed ω is increased by advancing the current phase β instead of increasing the magnitude Vm. is there.

  For example, in FIG. 7, the proportional restriction unit 535 restricts to the lower limit value when the output of the subtraction unit 534 is smaller than the lower limit value. That is, when the magnitude Vm is small, a lower limit value is output, and a value corresponding to the lower limit value is output as the current phase command value β *. On the other hand, when the magnitude Vm increases and the output of the subtracting unit 534 becomes larger than the lower limit value, a value corresponding to this output is output as the current phase command value β *, and a larger current phase command value β * is adopted. Will be. Thereby, the magnetic flux weakening control is executed.

  In the illustration of FIG. 7, although the peak extraction unit 531 is provided, the maximum value Vdc_p of the DC voltage Vdc is not necessarily used. For example, an average value or a minimum value of the DC voltage Vdc may be extracted and output to the division unit 532. Further, the DC voltage Vdc itself may be output to the division unit 532.

  By such a control device 5, the q-axis current command value iq * can be pulsated at substantially the same frequency and substantially the same phase as the current waveform of Equation (6), and thus the magnitude Vm is the same frequency as the DC voltage Vdc. And it can be made to pulsate with the same phase.

<Conditions for correcting the current command value>
By the way, when the magnitude Vm is smaller than the minimum value of the DC voltage Vdc, the magnitude Vm may be substantially constant (see also FIG. 2).

  Therefore, when the magnitude Vm is smaller than the minimum value of the DC voltage Vdc, the command correction unit 512 may output the q-axis current command value iq ** as it is as the q-axis current command value iq *. On the other hand, when the magnitude Vm is larger than the minimum value of the DC voltage Vdc, the command correction unit 512 performs the correction based on the current waveform on the q-axis current command value iq ** as described above. The q-axis current command value iq * may be generated.

  FIG. 10 is a diagram schematically illustrating an example of the internal configuration of the command correction unit 512. The command correction unit 512 includes, for example, a comparison unit 5121, a correction unit 5122, and a selection unit 5123. The correction unit 5122 performs correction based on the above-described current waveform on the q-axis current command value iq **, and outputs the result (Wq · iq **) to the selection unit 5123. The q-axis current command value iq ** is also directly input to the selection unit 5123 without passing through the correction unit 5122. The selection unit 5123 is controlled by the comparison unit 5121 and selects one input. Then, the selected one is output as the q-axis current command value iq *. That is, the selection unit 5123 selects one of the q-axis current command value iq ** and the result (Wq · iq **) according to the comparison result of the comparison unit 5121, and outputs this as the q-axis current command value iq *. To do.

  The comparison unit 5121 compares the magnitude Vm with the minimum value Vdc_b of the DC voltage Vdc. This minimum value Vdc_b is extracted based on the detected DC voltage Vdc. When the magnitude Vm is smaller than the minimum value Vdc_b of the DC voltage Vdc, the comparison unit 5121 causes the selection unit 5123 to select the q-axis current command value iq ** and the magnitude Vm is greater than the minimum value Vdc_b of the DC voltage Vdc. Is larger, the selection unit 5123 is made to select the result (Wq · iq **). When the magnitude Vm varies periodically, an average value of the magnitude Vm (an average value in the pulsation cycle) may be input to the comparison unit 5121. That is, it is only necessary to compare the average value of the magnitude Vm and the minimum value Vdc_c of the DC voltage Vdc.

<Result>
FIG. 11 shows an example of various electrical quantities when this control is used. In the illustration of FIG. 11, alternating currents iu, iv, iw, an input current Iin, and a direct current voltage Vdc are shown. The input current Iin is an alternating current input to the converter 2. For comparison, FIG. 12 shows an example of various electrical quantities in the case of using control (hereinafter referred to as comparison control) that outputs an output AC voltage with a substantially constant magnitude Vm. Also in FIG. 12, the same electrical quantities as in FIG. 11 are shown.

  FIGS. 13 to 15 schematically show examples of electrical quantities output to the rotating machine 4 when this control is used and electrical quantities when comparative control is used. 13 shows the relationship between the maximum value of the magnitude Vm of the output AC voltage and the rotational speed ω, FIG. 14 shows the relationship between the maximum value of the magnitude of the alternating current output to the rotating machine 4 and the rotational speed ω, FIG. 15 shows the relationship between the electric power supplied to the rotating machine 4 and the rotational speed ω.

  As can be understood from FIG. 15, the power in this control and the power in comparison control are substantially equal. On the other hand, as can be understood from FIG. 13, the maximum value of the magnitude Vm in the present control is higher than the maximum value of the magnitude Vm in the comparison control, particularly in a region where the rotational speed ω is high. Further, as can be understood from FIG. 14, the maximum value of the output AC current in this control is smaller than the maximum value of the output AC current in the comparative example, particularly in the region where the rotational speed ω is high.

  11 and 12 show various electrical quantities in a region where the rotational speed ω is high. It can be seen that the amplitudes of the alternating currents iu, iv, iw applied to the main control are smaller than the amplitudes of the alternating currents iu, iv, iw applied to the comparative control when the rotational speed ω is high.

  This is considered for the following reason. That is, as shown in FIG. 13, in the region where the rotational speed ω is low, the maximum value of the magnitude Vm increases as the rotational speed ω increases. When the magnitude Vm increases to the minimum value of the DC voltage Vdc, the magnetic flux control is performed in the comparison control to increase the rotational speed ω. By this weakening magnetic flux control, as shown in FIG. 14, the maximum value of the output alternating current increases steeply as the rotational speed ω increases.

  On the other hand, in this control, the output AC voltage can be output with a higher magnitude Vm by pulsating the magnitude Vm at substantially the same frequency and substantially the same phase as the DC voltage Vdc. Thereby, even if it is rotational speed (omega) which performs a weak flux control in comparison control, according to this control, the rotary machine 4 can be controlled, without performing a weak flux control. Alternatively, even if the flux-weakening control is executed, the advance amount of the current phase β can be reduced. As a result, the maximum value of the output alternating current can be reduced.

  As described above, according to this control, the maximum value of the output alternating current flowing through the armature winding can be reduced. Therefore, a winding having a small current capacity can be adopted as the armature winding of the rotating machine 4. This contributes to downsizing or cost reduction of the rotating machine 4.

  As described above, the normalized waveform Wq includes the power source phase θ, the rotational speed ω of the rotating machine 4, and the d-axis current id (= −iq * · tan β *) as variables. Therefore, even if a disturbance or the like that fluctuates these occurs, a normalized waveform Wq corresponding to the disturbance is generated. Therefore, robustness against disturbance can be improved.

  FIG. 16 shows an example of harmonic components included in the input current Iin. FIG. 16 shows the ratio of the magnitude of each harmonic to the effective value of the input current Iin. In the illustration of FIG. 16, the white bar graph indicates the harmonic component in the comparison control, and the black bar graph indicates the harmonic component in the comparison control. Here, 110 [rps] was employed as the rotational speed ω, and a three-phase alternating current power source having an amplitude of 200 [V] and a frequency of 50 Hz was employed as the alternating current power source 1. A compressor is employed as the load of the rotating machine 4, and the high pressure is 2.5 [MPa] and the low pressure is 0.6 [MPa].

  FIG. 16 also shows a prescribed line in IEC6100-3-12, and it can be seen that this prescribed line is satisfied even if this control is adopted. For example, according to this control, the seventh-order component can be reduced as compared with the case where comparison control is employed. On the other hand, the fifth order component is increasing. However, in the fifth-order component and the seventh-order component, the value with the smaller margin to the allowable value can be larger in this control than in the comparison control. Specifically, the margin to the boundary of the fifth component by this control is larger than the margin to the allowable value of the seventh component by the comparison control. That is, although there is a trade-off relationship between the fifth-order component and the seventh-order component between the comparison control and the main control, this control can improve the minimum value of these margins.

  In the comparison control, the ratio TCH / Iref of the total harmonic current THC to the reference current Iref is 28.8 [%], and the ratio PWHD / Iref of the partially weighted harmonic distortion PWHD to the reference current Iref is 59.2 [%. ]Met. The ratio THC / Iref according to this control was 30.0 [%], and the partially weighted harmonic distortion PWHD was 51.7 [%]. Therefore, according to this control, the ratio PWHD / Irec can be reduced by 7.5 [%] without significantly increasing the ratio THC / Irec.

<Q-axis current command value>
In the above example, the normalized waveform Wq is calculated by normalizing the current waveform with the maximum value, but the current waveform may be normalized with a value not less than the minimum value and not more than the maximum value, for example. From the viewpoint of responsiveness, it is desirable to perform normalization with a value close to the average value of the current waveform. This will be described in detail below.

  FIG. 8 schematically shows an example of q-axis current command values iq * and iq **. Here, as an example, since the maximum value of the normalized waveform Wq is set to 1, the q-axis current command value iq * is smaller than the q-axis current command value iq **. Therefore, when the correction is performed from the state where the correction based on the current waveform is not performed, the rotational speed ω can be transiently moved away from the rotational speed command value ω *.

  However, when the deviation Δω between the rotational speed command value ω * and the rotational speed ω increases, the q-axis current command value iq ** before correction calculated by the proportional integration control unit 51c of the next loop increases. Along with this, the q-axis current command value iq * also increases. As a result, a q-axis current command value iq * is generated so that the rotation speed ω approaches the rotation speed command value ω *.

  FIG. 17 is a diagram schematically showing an example of a transient change in the q-axis current command values iq ** and iq *. For example, a substantially constant value is adopted as the q-axis current command value iq * before the time point t1. That is, the correction based on the current waveform is not performed before the time point t1, and the q-axis current command value iq * matches the q-axis current command value iq **. At time t1, correction for the q-axis current command value iq ** is started. For simplicity, it is assumed that the rotational speed command value ω * is approximately equal before and after time t1.

  By this correction, the pulsating q-axis current command value iq * is adopted after time t1. Further, the q-axis current command value iq ** immediately after the time point t1 is equal to the q-axis current command value iq ** before the time point t1. Since the corrected q-axis current command value iq * is smaller than the q-axis current command value iq **, the rotational speed ω can transiently move away from the rotational speed command value ω * immediately after time t1. However, as the deviation Δω increases as described above, the q-axis current command value iq ** increases. Therefore, the q-axis current command value iq ** at time t2 is higher than the q-axis current command value iq ** at time t1. Along with this, the q-axis current command value iq * also increases.

  In FIG. 17, for example, the rotational speed ω is assumed to be steady after time t2. Here, since it is assumed that the rotational speeds ω are substantially equal before and after the time point t1, in the steady state, the average value of the q-axis current command value iq * (the average value in the pulsation cycle) is earlier than the time point t1. That is, it is substantially equal to the q-axis current command value iq * (before correction).

  In the example of FIG. 17, the q-axis current command value iq ** immediately after the time point t1 is schematically shown as a constant value, but actually increases gradually or with fluctuations with time. .

  In view of the above viewpoint, in order to shorten the transition period and increase the responsiveness, the q-axis current command value iq * may be calculated to be large in advance. That is, the q-axis current command value iq * close to the q-axis current command value iq * at the time point t2 may be calculated immediately after the time point t1.

  Therefore, the normalized waveform Wq may be calculated by normalizing the current waveform with a value between the maximum value and the minimum value of the current waveform in Expression (5). As a result, the maximum value of the normalized waveform Wq becomes larger than 1. Thereby, the q-axis current command value iq * can be calculated larger. That is, the q-axis current command value iq * closer to the q-axis current command value iq * after time t2 can be calculated immediately after time t1. For example, FIG. 18 schematically shows an example of the normalized waveform Wq when the current waveform is normalized by the average value of the current waveform of Equation (5), and FIG. 19 adopts the normalized waveform Wq of FIG. An example of q-axis current command values iq ** and iq * is shown schematically.

  If the normalized waveform Wq of FIG. 18 is employed, the q-axis current command value iq * whose average value is equal to the q-axis current command value iq ** can be calculated immediately after the time point t1. In other words, immediately after the time point t1, the q-axis current command value iq * after the time point t2 can be calculated. Therefore, the transition period can be minimized. In other words, the responsiveness can be improved most.

<Correction target>
In the above example, although correction is performed on the q-axis current command value iq **, correction may be performed on the d-axis current command value id *. That is, the d-axis current id is obtained from the equation (5), and the waveform is grasped as a current waveform. Then, correction based on the current waveform may be performed on the d-axis current command value id * to generate a corrected d-axis current command value. In this case, a substantially constant value may be adopted as the q-axis current command value iq *.

  However, since the d-axis current id has a negative value (see FIG. 8), the corrected d-axis current command value has a sharp waveform at the peak. If it demonstrates simply, this d-axis current command value will have a waveform similar to the waveform obtained by reversing the q-axis current command value iq * of FIG. Such a waveform causes an increase in the harmonic component of the input current Iin. Therefore, from this viewpoint, it is desirable to correct the q-axis current command value.

  In the above example, the current command value in the dq axis rotation coordinate system is corrected, but the present invention is not necessarily limited thereto. For example, a rotating coordinate system having an axis in phase with the vector of the output AC voltage may be adopted, or a rotating coordinate system having an axis in phase with the total magnetic flux of the rotating machine 4 may be adopted.

  In the above example, the current command value in the rotating coordinate system is corrected, but the present invention is not necessarily limited thereto. A current command value for a three-phase AC current is introduced, and the first axis current for causing the first axis component (first axis current) of the rotating coordinate system to match the magnitude Vm of the output AC voltage with the DC voltage Vdc. The current command value may be corrected based on the current waveform so that the current waveform periodically fluctuates in the same cycle and in the same phase.

  Further, in the rotating machine drive device and the control device 5, the above-described various embodiments can be appropriately modified and omitted within the scope of the invention as long as there is no contradiction.

2 Converter 3 Inverter 4 Rotating Machine 5 Control Device 52 Control Signal Generation Unit 511 Command Generation Unit 512 Command Correction Unit

Claims (4)

A converter (2) for full-wave rectifying the N (N is a natural number) phase AC voltage and outputting a rectified voltage between the first DC line (LH) and the second DC line (LL);
A capacitor (C1) connected between the first DC line and the second DC line and supporting a DC voltage (Vdc) pulsating at 2N times the frequency of the N-phase AC voltage;
A rotating machine drive device comprising: an inverter (3) that converts the DC voltage into an AC voltage based on a control signal, outputs the AC voltage to the rotating machine (4), and flows an AC current to the rotating machine. A device (5) for controlling
A command generator (511) for generating a command value of the alternating current;
A command correction unit (512) for correcting the command value and generating a corrected command value;
A control signal generation unit (52) for generating the control signal based on the corrected command value;
In a rotating coordinate system including a first axis and a second axis that are different from each other and rotating in accordance with the rotation of the rotating machine, the components of the first axis and the second axis of the alternating current are expressed as a first axis current (iq ) And second axis current (id)
The command correction unit is
Based on the rotational speed (ω) of the rotating coordinate system, the second axis current, the power supply phase of the N-phase AC voltage, and the device constant of the rotating machine, to make the magnitude of the AC voltage coincide with the DC voltage A current waveform of the first axis current of
A control device for a rotating machine drive device, wherein correction based on the current waveform is performed on the command value so that the first axis current fluctuates periodically with the same cycle and the same phase as the current waveform.   2. The rotating machine drive device according to claim 1, wherein the command correction unit (512) performs the correction when an average value of the magnitude of the AC voltage is larger than a minimum value of the DC voltage (Vdc). 3. Control device. The command generation unit (511) generates a first axis current command value for the first axis current as the command value,
The command correction unit (512) generates a normalized waveform (Wq) obtained by normalizing the current waveform with a value not less than the minimum value of the current waveform and not more than the maximum value of the current waveform. The control device for a rotating machine drive device according to claim 1, wherein the correction is performed by multiplying a current command value.   The control device for a rotating machine drive device according to claim 3, wherein the command correction unit obtains the normalized waveform by normalizing with an average value of the current waveform.

Images