JP2013062985A - Rotary electric machine controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a rotary electric machine by suppressing the impact of frequency components, detected due to aliasing, on the current feedback control while suppressing increase in operation load of a controller.SOLUTION: The rotary electric machine controller comprises a sampling period setting unit setting a sampling period ST for acquiring a detection current by sampling a real current containing AC frequency components, a current sampling unit acquiring a detection current by sampling the real current depending on the sampling period ST, and a current control unit having a response region R set so as to respond to the input of the frequency component of a predetermined frequency region, and performing current feedback control based on the detection current and a target current. The sampling period setting unit sets the sampling period ST according to the rotational speed of the rotary electric machine so that at least one of a plurality of aliasing frequencies of a detection current detected due to aliasing deviates from the response region R of the current control unit.

Description

  The present invention relates to a rotating electrical machine control apparatus that detects an actual current flowing through a rotating electrical machine and performs current feedback control so that the actual current approaches a target current of the rotating electrical machine to control the rotating electrical machine.

  An AC rotating electric machine that functions as an electric motor and a generator is often subjected to current feedback control in accordance with a deviation between a target current and an actual current flowing through the rotating electric machine by a control device that is configured with a microcomputer or the like as a core. In a microcomputer or the like, the actual current is often acquired by digital sampling corresponding to a predetermined sampling period. In digital sampling, it is necessary to pay attention to the sampling theorem between the sampling frequency that is the reciprocal of the sampling period and the frequency component of the signal to be measured. That is, for accurate digital sampling, it is necessary to use a sampling frequency that is twice or more the frequency component of the signal to be measured. When the frequency component of the signal to be measured exceeds 1/2 of the sampling frequency, low-frequency aliasing noise may appear due to a phenomenon called aliasing (also referred to as aliasing). For example, as described in Japanese Patent Application Laid-Open No. 2011-83068 (Patent Document 1), when the rotational speed of the rotating electrical machine increases, the frequency component of alternating current included in the actual current also increases, and this aliasing problem occurs. It becomes easier (6th paragraph etc.).

  By the way, in current feedback control, in many cases, an actual current is detected corresponding to one feedback calculation. For this reason, if the sampling period is shortened in order to suppress aliasing, the frequency of feedback calculation becomes higher than necessary, and the calculation load of the control device increases. Therefore, in Patent Document 1, while current is detected at each reference calculation cycle, current feedback calculation is performed using detection results for N times at a cycle N times the reference calculation cycle (N is an integer of 2 or more). This reduces the calculation load on the control device (7th to 9th paragraphs, etc.).

  By the way, the actual current of the rotating electrical machine to be measured includes a frequency component of a harmonic of the fundamental wave in addition to the frequency component of the fundamental wave corresponding to the rotation speed. Such harmonics appear over a plurality of frequency components such as the fifth, seventh, eleventh, and thirteenth of the fundamental frequency component. These higher-order harmonics often have a frequency component much higher than 1/2 of the sampling frequency, and can be dealt with by simply increasing the sampling frequency (shortening the sampling period). There is a limit.

JP 2011-83068 A

  In view of the above background, it is desirable to provide a technique for controlling the rotating electrical machine by suppressing the influence of the frequency component that appears due to aliasing on the current feedback control while suppressing an increase in the calculation load of the control device. It is.

In view of the above problems, the characteristic configuration of the rotating electrical machine control device according to the present invention is as follows.
A rotating electrical machine control device that detects an actual current flowing through the rotating electrical machine, performs current feedback control so that the actual current approaches a target current of the rotating electrical machine, and controls the rotating electrical machine,
A sampling period setting unit for setting a sampling period for sampling the actual current including the AC frequency component to obtain a detected current;
A current sampling unit that samples the actual current according to the sampling period to obtain a detected current;
A response region is set to respond to an input of a frequency component of a predetermined frequency region, and a current control unit that performs the current feedback control based on the detected current and the target current, and
The sampling period setting unit responds to the rotation speed of the rotating electrical machine so that at least one of a plurality of aliasing frequencies of the detected current detected due to aliasing is outside the response region of the current control unit. Thus, the sampling period is set.

  The aliasing frequency, which is the frequency of the noise signal superimposed on the detection current due to aliasing, is determined by the frequency component included in the actual current and the sampling frequency that is the reciprocal of the sampling period. That is, the aliasing frequency becomes a frequency in the response region in the current control unit, and whether or not the influence on the current feedback control is large can be determined by the rotation speed of the rotating electrical machine and the sampling frequency. For example, even if the detected current acquired in the current sampling unit includes an aliasing frequency, if the aliasing frequency is outside the response region of the current control unit, the influence on the current feedback control is slight.

  The actual current including the AC frequency component includes a plurality of frequency components including a fundamental wave component and a plurality of harmonic components. For this reason, a plurality of aliasing frequencies often appear in the detection current. According to this feature configuration, the sampling period is set according to the rotation speed so that at least one of the plurality of aliasing frequencies is outside the response region of the current control unit. That is, the sampling period is not simply shortened according to the rotation speed so as not to cause aliasing. The sampling period is set so that even if aliasing occurs, the sampling frequency becomes an aliasing frequency outside the response region, and the influence on the current Fordback control is suppressed. That is, the sampling period may be changed in a longer direction. Thus, according to this feature configuration, the sampling period is not shortened unilaterally, and the frequency component that appears due to aliasing is suppressed in current feedback control while suppressing an increase in the computation load of the control device. It is possible to control the rotating electrical machine while suppressing the influence.

  As described above, the number of aliasing frequencies that fall within the response region of the current control unit can be reduced by appropriately setting the sampling period. Further, by changing the response region, the aliasing frequency that falls within the response region can be set as an aliasing frequency outside the response region. Such a response region is often defined by a cutoff frequency. Therefore, it is possible to change the response region by changing the cutoff frequency. As one aspect, it is preferable that the rotating electrical machine control device according to the present invention further includes a response region setting unit capable of changing a cutoff frequency defining the response region of the current control unit.

  When all the aliasing frequencies that fall within the response region of the current control unit can be suppressed by appropriately setting the sampling period, the normal response region is maintained without changing the response region of the current control unit. In this way, responsiveness and followability can be ensured. Therefore, as one aspect, the response region setting unit of the rotating electrical machine control device according to the present invention includes at least one of the aliasing frequencies in the sampling region set by the sampling cycle setting unit. In this case, it is preferable to change the response region by lowering the cutoff frequency.

  As described above, since the actual current includes a plurality of frequency components of the fundamental wave component and the plurality of harmonic components, a plurality of aliasing frequencies may appear in the detected current. Aliasing frequencies having different amplitudes and frequencies have different effects on current feedback control. However, as one aspect, the smaller the number of aliasing frequencies having frequency components in the response region of the current control unit, the smaller the influence on the current feedback control. As one aspect based on such a viewpoint, in the rotating electrical machine control device according to the present invention, the sampling cycle setting unit is configured so that most of all the aliasing frequencies of the detected current are outside the response region. It is preferable to set the sampling period.

Block diagram schematically showing the configuration of a rotating electrical machine control device with a microcomputer as the core Block diagram schematically showing functional configuration of rotating electrical machine control using current feedback control The figure which shows the concept of the response region of the current controller Graph showing aliasing according to sampling frequency Graph showing relationship between aliasing frequency and cutoff frequency of current controller Map showing an example of sampling frequency (sampling period) according to rotation speed and cutoff frequency of response region A flowchart showing an example of a procedure for setting a sampling period and a cutoff frequency of a response region

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking as an example a rotating electrical machine control device that controls a rotating electrical machine serving as a regeneration source for a drive source of a vehicle such as a hybrid vehicle and an electric vehicle and a DC power source of the vehicle To do. For ease of explanation, in the present embodiment, a case where one rotating electrical machine is controlled will be described as an example. However, the present invention can also be applied to a rotating electrical machine control device that controls a plurality of rotating electrical machines. is there. Hereinafter, the rotary electric machine will be described as a “motor” as appropriate, and this refers to a rotary electric machine that functions as an electric motor and a generator.

  The block diagram of FIG. 1 schematically shows an example of a system configuration of a vehicle including such a control device (rotary electric machine control device) for the motor 20. As shown in FIG. 1, in this embodiment, the rotating electrical machine control device detects an actual current flowing through a motor 20 that is an AC rotating electrical machine (three-phase synchronous motor), and the actual current approaches the target current of the motor 20. Thus, the current feedback control is performed to drive and control the motor 20. As shown in FIG. 1, the motor 20 is electrically connected to a DC power supply 30 via an inverter 40. The DC power supply 30 may be a battery, or may include a battery and a converter that boosts the output voltage of the battery. The inverter 40 converts the DC power output from the DC power supply 30 into three-phase AC power (multiphase AC power). A motor 20 that functions as an electric motor is driven by the converted three-phase AC power. Further, when the motor 20 functions as a generator, the inverter 40 converts the generated three-phase AC power into DC power and regenerates it to the DC power supply 30.

  As is well known, the inverter 40 is constituted by a bridge circuit of a plurality of phases (here, three phases) using switching elements. It is preferable to apply an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET) to the switching element. The control terminal of each switching element is connected to an ECU (electronic control unit) 50 corresponding to the rotating electrical machine control device of the present invention via a driver circuit 55 described later, and is individually controlled to be switched.

  The ECU 50 includes a logic circuit such as a microcomputer or a DSP (digital signal processor) as a core. In the present embodiment, the ECU 50 includes a microcomputer 51, an interface circuit 52, and other peripheral circuits. The microcomputer 51 is a computer that executes a rotating electrical machine control program, and forms the core of the rotating electrical machine control device of the present invention. The interface circuit 52 includes EMI (electro-magnetic interference) countermeasure parts, a buffer circuit, and the like. The driver circuit 55 is a circuit that converts the voltage of a drive signal (switching control signal) that drives the switching element of the inverter 40. A drive signal input to a control terminal (gate terminal or the like) of an IGBT or MOSFET that switches a high voltage requires a voltage higher than a power supply voltage of a general electronic circuit such as a microcomputer. For this reason, the drive signal is voltage-converted (for example, boosted) through the driver circuit 55 and then input to the inverter 40.

  As shown in FIG. 1, the microcomputer 51 of the present embodiment includes, for example, a CPU core 11, a program memory 12, a parameter memory 13, a work memory 14, a communication control unit 15, and an A / D converter 16. And a timer 17 and a port 18. The CPU core 11 is the core of the microcomputer 51, and includes an instruction register, an instruction decoder, an ALU (arithmetic logic unit), a flag register, a general-purpose register, an interrupt controller, and the like that perform various operations. . That is, the rotating electrical machine control apparatus is configured mainly by the cooperation of the CPU core 11 and other hardware including the work memory 14 and the timer 17 with software such as programs and parameters stored in the program memory 12 and the parameter memory 13. Is done.

  The program memory 12 is a non-volatile memory that stores a motor control program (rotary electric machine control program). The parameter memory 13 is a non-volatile memory that stores various parameters that are referred to when the program is executed. The parameter memory 13 may be constructed without being distinguished from the program memory 12. Further, the program memory 12 and the parameter memory 13 are preferably constituted by a flash memory, for example. The work memory 14 is a memory that temporarily stores temporary data during program execution. The work memory 14 is composed of DRAM (dynamic RAM) or SRAM (static RAM) that is volatile and can read and write data at high speed.

  The communication control unit 15 controls communication with other systems in the vehicle. For example, communication with the traveling control system 60, other systems, sensors, and the like is controlled via a network such as a CAN (controller area network) in the vehicle. In the present embodiment, the microcomputer 51 receives a motor control command (for example, a required torque for the motor 20) from the travel control system 60 via the communication control unit 15, and controls the motor 20 based on this.

  The A / D converter 16 converts an analog electric signal into digital data. In the present embodiment, the detection result of the motor current flowing through each stator coil of the motor 20 is received from the current sensor 91 and converted into digital data. In the present embodiment, an example is shown in which the actual current of each of the three phases is detected by a current sensor 91 that detects the current in a non-contact manner in proximity to a current line such as a bus bar using the Hall effect. In the present embodiment, an example is shown in which the currents of all three phases are detected. However, since the three phases are balanced, only the two phases can be detected and the remaining one phase can be calculated by the microcomputer 51. Good.

  In the present embodiment, the rotating electrical machine control device (microcomputer 51) is defined by a d-axis set in the direction of the magnetic pole by a permanent magnet disposed on the rotor of the motor 20 and a q-axis orthogonal to the d-axis. The motor 20 is driven and controlled by vector control in the orthogonal vector space. As shown in FIG. 2, the rotating electrical machine control apparatus includes a main control unit 10 a that is a center of vector control calculation, and a management unit 10 b that manages calculation by the main control unit 10 a.

  The main control unit 10a includes a torque control unit 1 (current command determination unit), a current command map 1a, a current control unit 3 (voltage command determination unit), a feedback current coordinate conversion unit 4, and a voltage control unit 5 (drive). A command calculation unit), a position detection unit 93, a speed detection unit 94, and a current sampling unit 95. The inverter 40 is drive-controlled based on the drive command generated by the voltage control unit (drive command calculation unit) 5. The management unit 10b includes a control cycle setting unit 6 (sampling cycle setting unit), a response region setting unit 7, and a control condition map 6a. In the present embodiment, the calculation cycle (control cycle) by the main control unit 10a coincides with the sampling cycle of the actual current, and this cycle can be changed by the control cycle setting unit 6. Further, the response region of the frequency in the current feedback control can be changed by the response region setting unit 7. The management unit 10b is a functional unit that manages and sets these control conditions.

  Each functional unit that controls the motor 20 is realized by cooperation of hardware such as a microcomputer or DSP and software such as a program executed on the hardware. Accordingly, some or all of the functional units may share the same hardware or the same program module. Hereinafter, each functional unit will be described.

The torque control unit (current command determining unit) 1 is a command (target current) of a current that flows through the stator coil of the motor 20 in accordance with the target torque T ^* , and the current command id ^* corresponding to the d-axis and the q-axis, respectively ^. , Iq ^* is a functional unit that determines the current command map 1a. The current command map 1a is a map generated in advance based on, for example, a torque map that represents the relationship between d-axis current, q-axis current, and torque.

The current control unit (voltage command determination unit) 3 is a functional unit that determines voltage commands vd ^* and vq ^* which are commands of a voltage applied to the stator coil. The voltage control unit (drive command calculation unit) 5 is a functional unit that generates a drive signal for driving a switching element such as an IGBT constituting the inverter 40 based on the voltage commands vd ^* and vq ^* .

The current control unit 3 has a response region set so as to respond to frequency components in a predetermined frequency region, and performs current feedback control based on the detected currents iu, iv, iw and the target current (current commands id ^* , iq ^* ). I do. Specifically, the current control unit 3 uses proportional-integral control (PI control) or proportional-integral-derivative control (PID control) based on the deviation between the feedback currents id, iq and the current commands id ^* , iq ^* . Current control is performed to determine voltage commands vd ^* and vq ^* . The feedback currents id and iq are obtained by feeding back the detected currents iu, iv and iw obtained by detecting the actual current flowing through the stator coil by the current sampling unit 95 via the feedback current coordinate conversion unit 4. In the present embodiment, PI control is performed as shown in FIG. In FIG. _3, L d, _{L q} are, d-axis inductance, respectively, show the q-axis inductance, _{R a} denotes a resistance of the stator coil, s denotes a differential operator. Further, ω _C represents a cut-off frequency (cut-off angular frequency) that defines a response region of the PI controller of the current control unit 3. Here, PI controller is set with a low-pass filter characteristic so as to respond to the input of the frequency band below the cut-off frequency omega _C.

  The feedback current coordinate conversion unit 4 is a functional unit that performs coordinate conversion of the detected currents iu, iv, iw into two-phase feedback currents id, iq in the dq vector space based on the rotation angle θ of the rotor of the motor 20. . The detected currents iu, iv, and iw are obtained by sampling a three-phase actual current including an AC frequency component by the current sampling unit 95 according to the sampling period. The current sampling unit 95 is a functional unit realized by, for example, the A / D converter 16 or a general-purpose register of the CPU core. As one aspect, a value digitally converted by the A / D converter 16 is latched in a general-purpose register or the like of the CPU core 11 at predetermined sampling periods, and detection currents iu, iv, and iw are acquired. The rotation angle θ of the rotor is detected by the position detector 93 using the measurement result of the rotation sensor 92 such as a resolver. Similarly, the rotation speed ω of the rotor is detected by the speed detection unit 94 using the measurement result of the rotation sensor 92. Of course, the rotation sensor 92 may be configured to directly output the rotation angle θ and the rotation speed ω.

  By the way, in the discrete acquisition of data according to a predetermined sampling period, that is, in digital sampling, the sampling theorem between the sampling frequency (the reciprocal of the sampling period) and the frequency component included in the measurement object It is necessary to consider the impact. When the frequency component of the signal to be measured exceeds 1/2 of the sampling frequency, low-frequency aliasing noise that is 1/2 or less of the sampling frequency appears due to a phenomenon called aliasing. Therefore, for accurate sampling, it is necessary to use a sampling frequency that is twice the frequency component included in the measurement object.

  FIG. 4 schematically shows the relationship between the sampling frequency and aliasing. The vertical axis indicates the frequency (sampling result) of the actually detected signal, and the horizontal axis indicates the actual frequency of the detection target signal. The dotted line in the graph indicates the sampling result at the first sampling frequency fs1, that is, the sampling result when the sampling period ST is the first sampling period ST1. The solid line indicates the sampling result at the second sampling frequency fs2, that is, the sampling result when the sampling period ST is the second sampling period ST2.

  As described above, digital sampling has only a resolution up to half the sampling frequency. As shown in FIG. 4, the frequency of the sampling result with respect to the actual frequency changes linearly with a slope of “1” up to ½ of the sampling frequency. That is, the frequency of the sampling result matches the actual frequency. However, after 1/2 of the sampling frequency, the frequency of the sampling result decreases at the gradient “−1”, and after the sampling frequency, the frequency of the sampling result increases again at the gradient “1”. In this way, the frequency of the sampling result changes by repeating the gradients “1” and “−1” every ½ of the sampling frequency on the horizontal axis. After exceeding 1/2 of the sampling frequency on the horizontal axis, aliasing noise having a frequency (aliasing frequency) different from the actual frequency is generated.

  For example, when the frequency f1 shown in FIG. 4 is sampled at the first sampling frequency fs1 (first sampling period ST1), the frequency f1 is detected as the frequency fa2 and sampled at the second sampling frequency fs2 (second sampling period ST2). In this case, the frequency fa3 is detected. The frequency f1 is higher than the first sampling frequency fs1 and the second sampling frequency fs2, but the detected frequencies fa2 and fa3 are far more than half of the first sampling frequency fs1 and the second sampling frequency fs2. Low frequency. That is, the frequency f1 is detected as a noise signal having a frequency much lower than the actual frequency due to aliasing.

  As described above, the actual current is sampled by the current sampling unit 95 every predetermined sampling period ST. In the actual current, harmonics of the fundamental frequency are superimposed on the fundamental frequency corresponding to the rotational speed ω of the motor 20. This harmonic includes high-order harmonics such as the fifth, seventh, eleventh, and thirteenth, and the frequency of these higher-order harmonics is often higher than the sampling frequency. For this reason, the detection currents iu, iv, iw detected by the current sampling unit 95 are mixed with noise signals having a frequency (aliasing frequency) that is much lower than the actual frequency due to aliasing.

This low-frequency aliasing frequency noise signal also enters the current control unit 3 via the feedback current coordinate conversion unit 4. As described above, the current control unit 3 includes a PI controller that responds to a predetermined response region. This response region is defined by the cutoff frequency ω _C. For example, the frequency fc1 shown in FIG. 4 by a two-dot chain line corresponds to the cut-off frequency omega _C, the frequency range indicated by reference numeral R correspond to the response region R. If the frequency component of the noise signal that appears due to aliasing is higher than the frequency fc1 (cut-off frequency ω _C ), the responsiveness of the current control unit 3 is low, so the influence of the noise signal on the current feedback control is small. On the other hand, if the frequency component of the noise signal that appears due to aliasing is lower than the frequency fc1 (cut-off frequency ω _C ), the noise signal responds satisfactorily in the current control unit 3, and the noise signal is subjected to current feedback control. It will have a big impact.

By the way, referring to FIG. 4, the sampling results by the first sampling frequency fs1 (first sampling period ST1) and the second sampling frequency fs2 (second sampling period ST2) for the actual frequencies f1, f2, f3, and f4 are as follows. It becomes as follows.
First sampling frequency fs1 (first sampling period ST1)
Frequency fc1 or more: f2 (fa5), f4 (fa5)
Less than frequency fc1: f1 (fa2), f3 (fa1)
Second sampling frequency fs2 (second sampling period ST2)
Frequency fc1 or more: f1 (fa3), f3 (fa4), f4 (fa6)
Less than frequency fc1: f2 (fa2)

  For example, when the motor 20 has a rotational speed ω, the frequency components of the harmonics superimposed on the actual current are frequencies f1, f2, f3, and f4. When the actual current is sampled at the first sampling frequency fs1 and the detection currents iu, iv, and iw are acquired, the noise signals of the aliasing frequencies (frequency fa2 and fa1) for the two frequencies f1 and f3 affect the current feedback control. It will be. On the other hand, when the actual current is sampled at the second sampling frequency fs2 and the detection currents iu, iv, and iw are acquired, only the noise signal of the aliasing frequency (frequency fa2) for one frequency f2 affects the current feedback control. become.

  Therefore, in this case, it is preferable that the current sampling unit 95 acquires the detected currents iu, iv, iw by sampling the actual current at the second sampling frequency fs2 (second sampling period ST2). A sampling period setting unit that sets a sampling period for sampling a real current including an AC frequency component to acquire a detected current sets the sampling period to a more appropriate period. In the present embodiment, since the actual current is sampled once in one control cycle, the sampling cycle ST (the reciprocal of the sampling frequency) matches the control cycle. Therefore, the control cycle setting unit 6 of the management unit 10b corresponds to the sampling cycle setting unit, and the control cycle setting unit 6 sets the control cycle so that the sampling cycle ST becomes the second sampling cycle ST2. That is, the control cycle setting unit 6 (sampling cycle setting unit) has at least one of a plurality of aliasing frequencies of the detected currents iu, iv, iw detected due to aliasing to be outside the response region R of the current control unit 3. Thus, the sampling cycle ST is set according to the rotational speed ω of the motor 20. More preferably, the control cycle setting unit 6 (sampling cycle setting unit) may set the sampling cycle ST so that most of all aliasing frequencies of the detected current are outside the response region R.

  FIG. 5 illustrates a case where the control cycle setting unit 6 sets the sampling cycle ST to be the second sampling cycle ST2. As described above, by appropriately setting the sampling cycle ST, it is possible to suppress the influence of the aliasing frequency included in the detection currents iu, iv, iw on the current feedback control. However, as will be described below, by changing the response region R of the current control unit 3, it is possible to further suppress the influence of the aliasing frequency included in the detected currents iu, iv, and iw on the current feedback control. is there.

For example, in this embodiment, as described above, even if the actual current is sampled at the second sampling frequency fs2 (second sampling period ST2), below the frequency fc1 corresponding to the cutoff frequency omega _C of the current controller 3 A noise signal having an aliasing frequency (frequency fa2) is mixed in the detection currents iu, iv, and iw. Here, as shown in FIG. 5, when the cut-off frequency ω _C is lowered by Δω _C , the frequency corresponding to the cut-off frequency ω _C changes from the frequency fc1 to the frequency fc2 (frequency fa1). This frequency fc2 is a frequency lower than the frequency fa2 of the noise signal. Accordingly, all aliasing frequencies are higher than the cutoff frequency ω _C (= frequency fc2). That is, it is possible to suppress the influence of noise signals of all aliasing frequencies on the harmonic frequencies f1, f2, f3, and f4 superimposed on the actual current.

Response area setting unit 7 of the management unit 10b is a functional unit capable of changing the cutoff frequency omega _C defining the response region R of the current control unit 3. As one aspect, the response region setting unit 7 includes a case where at least one of the aliasing frequencies is included in the response region R in the sampling cycle ST set by the control cycle setting unit 6 (sampling cycle setting unit) as described above. the changes the response region R by lowering the cutoff frequency omega _C.

As one aspect, the control cycle setting unit 6 (sampling cycle setting unit) and the response region setting unit 7 of the management unit 10b refer to the control condition map 6a using the rotation speed ω as an argument, and the sampling cycle ST (control cycle). And a cut-off frequency ω _C is set. FIG. 6 shows an example of the control condition map 6a. In FIG. 6, a solid line indicates a map of sampling frequency, and a broken line indicates a map of cut-off frequency. FIG. 6 shows an example in which four types of frequencies (fs1, fs2, fs3, fs4) from the first sampling frequency fs1 to the fourth sampling frequency fs4 can be selected as sampling frequencies. For example, the first sampling frequency fs1 is 5 [kHz], the second sampling frequency fs2 is 4.5 [kHz], the third sampling frequency fs3 is 4 [kHz], and the fourth sampling frequency is 3.5 [kHz]. Different frequencies can be used. The aliasing frequency is determined by the relationship between the sampling target signal and the sampling frequency. Therefore, when the sampling frequency is set as a frequency value such that the common divisor common to each other is reduced (the least common multiple is increased) so that the same aliasing frequency does not occur for the same frequency component. Is preferred.

Further, in FIG. 6, as a cut-off frequency omega _C, the first cut-off frequency fc1, a second cutoff frequency fc2 indicates the selectable example. For example, the angular velocity (2π · fc1) based on the first cutoff frequency fc1 is set to 1500 [rad / s], and the angular velocity (2π · fc2) based on the second cutoff frequency fc2 is set to 750 [rad / s]. it can.

  In FIG. 6, a white mark indicates that the corresponding rotation speed is not included, and a filled mark indicates that the corresponding rotation speed is included. 6 uses the first sampling frequency fs1 when the rotational speed ω is in the range from v0 to less than v1 and v5, and uses the second sampling frequency fs2 in the range from v1 to less than v2 and from v4 to less than v5. The third sampling frequency fs3 is used in the range below v3, and the fourth sampling frequency fs4 is used in the range from v3 to less than v4. FIG. 6 shows that when the rotational speed ω is greater than v0 and less than or equal to v2 and greater than v4 and less than v5, the first cutoff frequency fc1 (angular velocity 2π · fc1) is used. In this case, and in the case of greater than v2 and less than or equal to v4, the second cutoff frequency fc2 (angular velocity 2π · fc1) is used.

  The flowchart of FIG. 7 shows the flow of a program (management program) executed mainly as a function of the management unit 10b. A program (main program) executed mainly as a function of the main control unit 10a is executed in parallel with the flowchart of FIG. 7 or in the flowchart of FIG. 7 as appropriate. The illustration and detailed description of the program are omitted.

  First, the current control cycle of the main program corresponding to the current actual current sampling cycle ST is acquired (# 1). Next, the rotational speed ω of the motor 20 detected by the speed detector 94 is acquired (# 2). Subsequently, based on the rotational speed ω, for example, the control cycle setting unit 6 calculates the frequency of the fundamental wave (fundamental frequency) constituting the waveform of the actual current and the frequency of the harmonic of the fundamental wave (# 3). Of course, in order to realize the function of step # 3, a harmonic frequency calculation unit or the like may be provided separately. In the present embodiment, odd-order harmonics are generated, but since the motor 20 is a three-phase synchronous motor, harmonics of orders that are multiples of 3 are suppressed. For example, fifth, seventh, eleventh, and thirteenth The following harmonic components are superimposed on the actual current.

Based on the obtained harmonic component frequency and the sampling frequency (the reciprocal of the sampling period ST), for example, the control period setting unit 6 derives the optimum sampling period ST _B within a settable range (# 4). That is, it is optimal that at least one of a plurality of aliasing frequencies appearing in the detected current due to aliasing, preferably, most of all the aliasing frequencies are outside the response region of the current control unit 3. A sampling cycle ST _B is obtained. If the sampling period ST can be continuously set to an arbitrary value, an optimum value within the variable range is derived. As described above with reference to FIG. 6, an optimum mode may be selected from among a plurality of sampling periods ST (sampling frequency).

When the optimum sampling period ST _B is derived, it is determined whether or not the current sampling period ST and the optimum sampling period ST _B match (# 5). If the current sampling period ST is different from the optimum sampling period ST _B , the current sampling period ST is changed to the optimum sampling period ST _B (# 6). If the current sampling period ST matches the optimum sampling period ST _B , the sampling period ST is not changed and the process proceeds to the next step.

Then, in response region setting unit 7, whether the cutoff frequency omega _C below aliasing frequencies that define the response region of the current control unit 3 there is determined (# 7). When there is no aliasing frequency equal to or lower than the cutoff frequency ω _C , the response region setting unit 7 determines (sets) the value of the cutoff frequency ω _C as the initial setting value as the cutoff frequency ω _C (# 10). . On the other hand, when one or more aliasing frequencies equal to or lower than the cut-off frequency ω _C exist, a decrease width Δω that reduces the cut-off frequency ω _C so that the aliasing frequency falls outside the response region within the settable range. _C is derived (# 8).

If the cut-off frequency ω _C can be continuously set to an arbitrary value, an optimum value within the settable range is derived as the decrease width Δω _C. Also, as described above with reference to FIG. 6, if the form of selecting the optimum from among a plurality of cut-off frequency omega _C, the decline [Delta] [omega _C up to the cutoff frequency omega _C, which is selected It is preferred that it be derived. If the aliasing frequency does not fall outside the response region even when the cut-off frequency ω _C is reduced within the settable range, the maximum reduction width allowed for ensuring the responsiveness of the current control unit 3 When [Delta] [omega _C is set it is suitable. When the decrease width Δω _C is obtained, the response area setting unit 7 changes the response area by reducing the cut-off frequency ω _C by the decrease width Δω _C (# 9).

  As described above, according to the present invention, since the control cycle is not significantly changed in order to suppress the influence of aliasing, an increase in the calculation load of the rotating electrical machine control device is suppressed. In addition, since the control period (sampling period) is set so that the aliasing frequency is outside the current control response region, the influence of the aliasing frequency on the current feedback control is also suppressed.

[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described. Note that the configuration of each embodiment described below is not limited to being applied independently, and can be applied in combination with the configuration of other embodiments as long as no contradiction arises.

(1) In the said embodiment, the example which changes both sampling period ST and cutoff frequency (omega) _C was shown as a suitable aspect. However, without changing the cutoff frequency omega _C, may be configured to set only the proper sampling period ST. For example, the management unit 10b may not include the response region setting unit 7, but may be configured by a control cycle setting unit 6 (sampling cycle setting unit) and a control condition map 6a.

(2) The sampling period ST and the cut-off frequency ω _C are not necessarily set as in the procedure shown in the flowchart of FIG. For example, the sampling period ST and the cut-off frequency ω _C may be uniquely determined according to the rotational speed ω according to the control condition map 6a illustrated in FIG.

(3) In the above-described embodiment, the case where the PI control unit of the current control unit 3 has a low-pass filter characteristic is illustrated. For this reason, in order to change a filter characteristic, the example which reduces a cutoff frequency was shown, However, The change of a filter characteristic is not limited to reducing a cutoff frequency. For example, when the filter characteristic has a band pass characteristic, either the upper limit frequency or the lower limit frequency may be changed. In this case, the upper limit frequency may be decreased or the lower limit frequency may be increased. Further, both the upper limit frequency and the lower limit frequency may be lowered or both may be raised. That is, it is only necessary to change the characteristics of the response region so that the responsiveness of the aliasing frequency remaining even if the sampling frequency is changed.

(4) In the above embodiment, the case where the control cycle, which is the cycle of calculation by the main control unit 10a, matches the sampling cycle of the actual current has been described as an example. However, the control period and the sampling period may be set to different periods. In the example described above with reference to FIG. 2, the case where the control cycle setting unit 6 is a sampling cycle setting unit is illustrated. However, when the control cycle and the sampling cycle are set to different periods, or the control cycle is constant. In the case where only the sampling period is variable, an independent sampling period setting unit may be provided.

  The present invention is applied to a rotating electrical machine control device that controls the rotating electrical machine by suppressing the influence of the frequency component detected due to aliasing on the current feedback control while suppressing an increase in calculation load of the control device. can do.

ω: rotational speed ω _C : cut-off frequency 3: current control unit 6: control cycle setting unit (sampling cycle setting unit)
7: Response region setting unit 20: Motor (rotating electric machine)
30: DC power supply ST: Sampling period iu, iv, iw: Detection current

Claims (4)

A rotating electrical machine control device that detects an actual current flowing through the rotating electrical machine, performs current feedback control so that the actual current approaches a target current of the rotating electrical machine, and controls the rotating electrical machine,
A sampling period setting unit for setting a sampling period for sampling the actual current including the AC frequency component to obtain a detected current;
A current sampling unit that samples the actual current according to the sampling period to obtain a detected current;
A response region is set to respond to an input of a frequency component of a predetermined frequency region, and a current control unit that performs the current feedback control based on the detected current and the target current, and
The sampling period setting unit responds to the rotation speed of the rotating electrical machine so that at least one of a plurality of aliasing frequencies of the detected current detected due to aliasing is outside the response region of the current control unit. A rotating electrical machine control device for setting the sampling period.   The rotating electrical machine control device according to claim 1, further comprising a response region setting unit capable of changing a cutoff frequency defining the response region of the current control unit.   The response region setting unit lowers the cutoff frequency and changes the response region when at least one of the aliasing frequencies is included in the response region in the sampling period set by the sampling period setting unit. The rotating electrical machine control device according to claim 2.   The rotation according to any one of claims 1 to 3, wherein the sampling period setting unit sets the sampling period so that most of all aliasing frequencies of the detection current are outside the response region. Electric control device.

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