Drive device, compressor drive system, and refrigeration cycle device

Abstract

A drive device (4) that drives an AC motor (1) by an inverter (11) includes a current detection unit (12) that detects a current flowing through the AC motor, a rotor position calculation unit (14) that calculates rotor position information that is information about the position of a rotor of the AC motor, a voltage command determination unit (15) that determines a voltage command based on a current vector of a current and the rotor position information, and a beatless control unit (18) that suppresses current pulsation caused by periodic pulsation of a DC bus voltage by manipulating the voltage phase of the voltage command. The beatless control unit has a plant information calculation unit (107) that calculates plant information that is a characteristic of a plant of the AC motor, and manipulates the voltage phase based on the plant information and a pulsation component of the norm of the current vector.

Description

[Technical Field]

[0001] The present disclosure relates to a drive device that drives a driven object using AC power, a compressor drive system, and a refrigeration cycle device. [Background technology]

[0002] Drive systems that combine an AC (Alternating Current)-DC (Direct Current) converter with a DC-AC converter (inverter) are widely used to drive AC motors. A capacitor is used in the DC bus section of this drive system. A reactor is often inserted on the AC-DC converter side to improve the power factor and boost voltage. With the aim of reducing costs, efforts are being made to reduce the size and capacity of the capacitors and reactors used in these drive systems.

[0003] However, using a small-capacity capacitor or reactor increases the periodic pulsation of the DC bus voltage, adversely affecting the current control of the AC motor. In particular, when the pulsation frequency (disturbance frequency) of the DC bus voltage and the phase current frequency of the AC motor become close, a low-frequency current pulsation called beat vibration occurs. When the phase current pulsates due to beat vibration, disadvantages arise, such as a decrease in motor efficiency due to an increase in the current peak value, a decrease in the maximum output of the motor due to restrictions on overcurrent protection, and increased vibration or noise in the AC motor.

[0004] Various methods have been proposed for beatless control, which is a control method for suppressing beat vibration. For example, a drive device that performs beatless control detects at least one of the DC bus voltage and the motor current, extracts the pulsating component contained in the detected DC bus voltage or motor current using a band-pass filter or the like, and performs feedback control to reduce the extracted pulsating component, thereby suppressing beat vibration.

[0005] The beatless control of Patent Document 1 uses the principle of Fourier series to extract the cosine (cosine) component and sin (sine) component contained in the pulsation of the q-axis current, and after proportional control or integral control of these, restores the control results to AC signals and corrects the dq-axis voltages output to the inverter. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4988329 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technique of Patent Document 1 described above has the problem that it is not possible to perform desired voltage manipulation in the voltage saturation region of the inverter voltage, and therefore it is not possible to reduce pulsation as intended.

[0008] The present disclosure has been made in view of the above, and has an object to provide a drive device that can reduce pulsation as intended even in the voltage saturation region of the inverter voltage. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, a drive device disclosed herein is a drive device that drives an AC motor using an inverter, and includes a current detection unit that detects a current flowing through the AC motor, and a rotor position calculation unit that calculates rotor position information, which is information about the position of a rotor of the AC motor. The drive device disclosed herein also includes a voltage command determination unit that determines a voltage command based on a current vector of the current and the rotor position information, and a beatless control unit that suppresses current pulsation caused by periodic pulsation of a DC bus voltage by manipulating the voltage phase of the voltage command. The beatless control unit is a drive device that drives an AC motor using an inverter. Changes with the change in rotation speed based on the electrical angular velocity Plant characteristics InformationThe plant information calculation unit calculates plant information as follows: and operates the voltage phase based on the plant information and the pulsation component of the norm of the current vector. [Effects of the Invention]

[0010] The drive device according to the present disclosure has the effect of being able to reduce pulsation as intended even in the voltage saturation region of the inverter voltage. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a configuration of a driving device according to a first embodiment; [Figure 2] FIG. 10 is a diagram for explaining beat vibration when the driving device according to the first embodiment does not perform voltage phase manipulation; [Figure 3] FIG. 1 is a diagram for explaining the principle by which the driving device according to the first embodiment suppresses beat vibration by controlling the voltage phase. [Figure 4] 1 is an equivalent block diagram of a first example of an AC motor driven by a drive device according to a first embodiment; [Figure 5] 10 is an equivalent block diagram of a second example of an AC motor driven by the drive device according to the first embodiment; [Figure 6] FIG. 1 is a diagram showing an example of a Bode diagram from dq-axis voltages to dq-axis currents of an AC motor driven by a drive device according to a first embodiment; [Figure 7] FIG. 1 is a diagram showing a configuration of a beatless control unit included in a drive device according to a first embodiment; [Figure 8] FIG. 1 is a diagram showing a configuration of a pulsation suppression unit included in a beatless control unit according to a first embodiment; [Figure 9] FIG. 10 is a diagram showing a configuration of a rotation amount adjustment unit included in the beatless control unit according to the first embodiment; [Figure 10] FIG. 10 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the first embodiment performs beatless control when the rotation amount is in an optimal state. [Figure 11]FIG. 10 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the first embodiment performs beatless control when the rotation amount is within a range of less than ±90 degrees from the optimal value. [Figure 12] FIG. 10 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the first embodiment performs beatless control when the rotation amount is in a state where it is more than ±90 degrees away from the optimal value. [Figure 13] 10 is a flowchart showing a procedure of a control process executed by a control unit of the drive device according to the first embodiment; [Figure 14] 10 is a flowchart showing a procedure of beatless control processing executed by a beatless control unit of the drive device according to the first embodiment; [Figure 15] 10 is a flowchart showing a procedure of a pulsation suppression process executed by a pulsation suppressor of the drive device according to the first embodiment; [Figure 16] FIG. 1 is a diagram illustrating an example of a hardware configuration that realizes a control unit included in a driving device according to a first embodiment. [Figure 17] FIG. 10 is a diagram showing a configuration of a pulsation suppression unit included in a beatless control unit according to a second embodiment. [Figure 18] FIG. 10 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the second embodiment executes beatless control. [Figure 19] FIG. 10 is a first explanatory diagram for explaining a search direction corrected by a beatless control unit according to a second embodiment; [Figure 20] FIG. 2 is a second explanatory diagram for explaining a search direction corrected by the beatless control unit according to the second embodiment; [Figure 21] FIG. 3 is a third explanatory diagram for explaining a search direction corrected by the beatless control unit according to the second embodiment; [Figure 22] FIG. 4 is a fourth explanatory diagram for explaining a search direction corrected by the beatless control unit according to the second embodiment; [Figure 23] FIG. 10 is a diagram showing a first behavior of a deviation vector when a beatless control unit according to a second embodiment is performing beatless control. [Figure 24]FIG. 10 is a diagram illustrating a second behavior of the deviation vector when the beatless control unit according to the second embodiment is performing beatless control. [Figure 25] FIG. 10 is a diagram illustrating a third behavior of the deviation vector when the beatless control unit according to the second embodiment is performing beatless control. [Figure 26] FIG. 10 is a diagram illustrating an evaluation value used by the pulsation suppression unit according to the second embodiment to evaluate whether beatless control is being performed appropriately. [Figure 27] FIG. 10 is a diagram showing the configuration of a rotation amount adjusting unit included in a pulsation suppressing unit according to a second embodiment; [Figure 28] 10 is a flowchart showing a procedure of a rotation amount adjustment process executed by a rotation amount adjustment unit according to a second embodiment; [Figure 29] FIG. 11 is a diagram showing a configuration of a beatless control unit included in a drive device according to a third embodiment. [Figure 30] FIG. 11 is a diagram showing a configuration of a pulsation suppression unit included in a beatless control unit according to a third embodiment. [Figure 31] FIG. 10 is a diagram showing the configuration of a refrigeration cycle device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] A drive device, a compressor drive system, and a refrigeration cycle device according to embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0013] Embodiment 1 FIG. 1 is a diagram showing the configuration of a drive device according to a first embodiment. The drive device 4 is a device that converts AC power into desired power and drives an AC motor 1. The rotating shaft of the AC motor 1 is mechanically connected to a mechanical device 2. The mechanical device 2 is, for example, a refrigerant compression mechanism. The AC motor 1 and the mechanical device 2 form a compressor 3. A system including the drive device 4 and the compressor 3 is a compressor drive system 800, which will be described later.

[0014] The compression mechanism is merely one example of the mechanical device 2 driven by the AC motor 1, and the drive device 4 can be applied to other types of mechanical devices. The drive device 4 converts AC power input from an AC power source 5 to drive the AC motor 1. A source impedance (parasitic impedance) exists between the drive device 4 and the AC power source 5. The source inductance 6 is the inductance component of the source impedance.

[0015] For convenience of explanation, the case where the AC power supply 5, which is the input power supply, is a three-phase AC power supply will be described here, but the driving device 4 of the first embodiment is also applicable when the AC power supply 5 is a single-phase AC power supply.

[0016] The driving device 4 includes a diode rectifier 7 , a DC reactor 8 , a capacitor 9 , a DC bus voltage detector 10 , an inverter 11 , a current detector 12 , and a controller 400 .

[0017] In the drive unit 4, an AC-DC converter is configured by a diode rectifier 7, a DC reactor 8, a capacitor 9, etc. The drive unit 4 converts the input AC voltage into a DC voltage using this AC-DC converter. The AC-DC converter shown in Fig. 1 is a very simple AC-DC converter, but if power factor correction or voltage boosting is required, a different type of AC-DC converter may be used.

[0018] One end of DC reactor 8 is connected to the positive output point of diode rectifier 7, and the other end of DC reactor 8 is connected to the positive input point of inverter 11. In addition, one end of capacitor 9 is connected to the other end of DC reactor 8. The other end of capacitor 9 is connected to the negative output point of diode rectifier 7 and the negative input point of inverter 11. DC reactor 8 and capacitor 9 are provided to smooth the DC power output from diode rectifier 7.

[0019] The DC bus voltage detector 10 detects the voltage across the capacitor 9 as the DC bus voltage V DCand outputs it to the control unit 400. The inverter 11 converts the DC voltage into an AC voltage, and drives the AC motor 1 with the AC voltage.

[0020] The current detection unit 12 detects the phase current (phase current vector I uvw ) and outputs it to the control unit 400. The control unit 400 performs a series of control calculations for driving the AC motor 1. The detailed hardware configuration of the control unit 400 will be described later.

[0021] The control unit 400 has a modulation unit 13, a rotor position calculation unit 14, a voltage command determination unit 15, a coordinate conversion unit 16, a coordinate conversion unit 17, a beatless control unit 18, and an adder 19. The coordinate conversion unit 17 is a first coordinate conversion unit, and the coordinate conversion unit 16 is a second coordinate conversion unit.

[0022] The control unit 400 controls the AC motor 1 in a rotating two-phase coordinate system. Here, a case will be described in which the control unit 400 performs control in a dq rotating coordinate system based on the direction of the rotor magnet, but the control unit 400 may also perform control in a coordinate system other than the dq rotating coordinate system.

[0023] The control unit 400 calculates the angle difference between the fixed two-phase coordinates and the rotating two-phase coordinates in order to perform control in the rotating two-phase coordinate system. * dq and the dq-axis current vector I dq From this, the estimated magnetic pole position θ^ e and estimated angular velocity ω^ e It is estimated that * Information indicated with " is command information, and information indicated with "^" is inferred information.

[0024] dq-axis voltage command vector V * dq corresponds to the voltage that the inverter 11 applies to the AC motor 1. The dq-axis voltage command vector V * dq is the voltage command vector in the dq rotating coordinate system.

[0025] dq-axis current vector I dq is a current vector that is actually detected by the current detection unit 12 and is coordinate-transformed into the dq rotating coordinate system. e is information that estimates the magnetic pole position of the rotor of the AC motor 1. e is information that estimates the angular velocity of the rotor.

[0026] There are various methods for estimating the magnetic pole position of the rotor from the speed electromotive force generated while the AC motor 1 is rotating, such as an adaptive magnetic flux observer or an extended induced voltage observer. The control unit 400 may also directly observe the magnetic pole position of the rotor using a position sensor such as an encoder or a resolver. The control unit 400 calculates the angular velocity of the rotor based on the magnetic pole position of the rotor.

[0027] The coordinate conversion unit 17 converts the phase current vector (three-phase current vector) I of the AC motor 1 from the current detection unit 12. uvw The coordinate conversion unit 17 receives the phase current vector I uvw The dq-axis current vector I dq That is, the coordinate conversion unit 17 converts the three-phase current vectors into two vectors (d-axis current vector and q-axis current vector) that are current vectors in a rotating two-phase coordinate system. The coordinate conversion unit 17 converts the estimated magnetic pole position θ^ e That is, the coordinate conversion unit 17 uses the estimated magnetic pole position θ^, which is rotor position information. e The coordinate transformation unit 17 performs a rotational two-phase transformation based on the dq-axis current vector I dq are output to the rotor position calculation unit 14, the voltage command determination unit 15, and the beatless control unit 18.

[0028] The voltage command determination unit 15 determines a voltage command to be applied to the AC motor 1. That is, the voltage command determination unit 15 executes speed control calculation and current control calculation to determine the dq-axis current vector I dq to the dq-axis voltage command vector V * dqThe voltage command determination unit 15 determines the dq-axis current vector I by, for example, vector control. dq into a d-axis current vector and a q-axis current vector to determine a d-axis voltage command vector and a q-axis voltage command vector. Then, the voltage command determination unit 15 determines a dq-axis voltage command vector V * dq The voltage command determination unit 15 determines the speed command ω * e and the estimated angular velocity ω^ sent from the rotor position calculation unit 14 e The dq-axis voltage command vector V * dq Determine the speed command ω * e is a command for the angular velocity of the rotor. The voltage command determination unit 15 receives a speed command ω from a host program used by a host device of the drive device 4. * e The voltage command determination unit 15 obtains the dq-axis voltage command vector V * dq is output to the rotor position calculation unit 14 and the coordinate conversion unit 16.

[0029] The rotor position calculation unit 14 calculates the position information (rotor position information) of the rotor of the AC motor 1. Specifically, the rotor position calculation unit 14 calculates the dq-axis voltage command vector V * dq and the dq-axis current vector I dq From this, the estimated magnetic pole position θ^ e and estimated angular velocity ω^ e It is estimated that:

[0030] If a position sensor for detecting the rotor position is provided in the compressor 3, the rotor position calculation unit 14 calculates the estimated magnetic pole position θ^ based on the rotor position detected by the position sensor. e and estimated angular velocity ω^ e The rotor position calculation unit 14 may estimate (calculate) the estimated magnetic pole position θ^. e to the coordinate conversion unit 17 and the adder 19. The rotor position calculation unit 14 also outputs the estimated angular velocity ω^ eis output to the voltage command determination unit 15.

[0031] The beatless control unit 18 controls the DC bus voltage V by manipulating the voltage phase of the voltage command to the inverter 11. DC The beatless control unit 18 suppresses the pulsation of the motor current (current of the AC motor 1) caused by the periodic pulsation of the disturbance frequency f input by the user. dis Based on this, the dq axis current vector I dq The disturbance frequency f included in dis The voltage phase control amount (phase change amount) θ is used to reduce the extracted component. b At this time, the beatless control unit 18 determines the speed command ω * e One of the features of the driving device 4 of the first embodiment is that it calculates plant information, which is the plant characteristic of the AC motor 1, based on the disturbance frequency f dis is the DC bus voltage V DC The beatless control unit 18 controls the voltage phase by the manipulated variable θ b to the adder 19. In this way, the beatless control unit 18 outputs the manipulated variable θ b By outputting the voltage command, the voltage phase of the voltage command to the inverter 11 is controlled, thereby suppressing the pulsation of the motor current. The detailed internal configuration and effects of the beatless control unit 18 will be described later.

[0032] The adder 19 calculates the estimated magnetic pole position θ^ sent from the rotor position calculation unit 14. e The voltage phase control amount θ sent from the beatless control unit 18 b By adding the phase angle θ^ eb That is, the adder 19 determines the voltage phase control amount θ b and estimated magnetic pole position θ^ e The sum of these is the phase angle θ^ eb The phase angle θ^ is determined as follows. eb is the disturbance frequency f dis The rotor pole position is adjusted to suppress the pulsation corresponding to the phase angle θ^.eb is sent to the coordinate conversion unit 16.

[0033] The coordinate conversion unit 16 converts the phase angle θ^ eb Using the dq-axis voltage command vector V * dq is the three-phase voltage command vector V * uvw That is, the coordinate conversion unit 16 converts the rotor magnetic pole position (phase angle θ^) adjusted to suppress pulsation into eb ) based on the three-phase voltage command vector V * uvw Specifically, the coordinate conversion unit 16 generates the phase angle θ̂ eb Using the dq-axis voltage command vector V * dq The voltage phase of the dq-axis voltage command vector V * dq is the three-phase voltage command vector V * uvw The coordinate conversion unit 16 converts the three-phase voltage command vector V * uvw is output to the modulation unit 13.

[0034] The modulation unit 13 determines a PWM (Pulse Width Modulation) signal for operating the inverter 11. Specifically, the modulation unit 13 modulates the DC bus voltage V DC and the three-phase voltage command vector V sent from the coordinate conversion unit 16 * uvw Based on this, a PWM signal is determined and output to the inverter 11.

[0035] The inverter 11 outputs a voltage corresponding to the PWM signal to the AC motor 1. As a result, the AC motor 1 is driven by the driving device 4. Generally, when the capacity of the DC reactor 8 or the capacitor 9 is reduced, the DC bus voltage V DC When the input is a three-phase AC power supply, the DC bus voltage V DC It is known that the disturbance frequency, which is the pulsation frequency of the DC bus voltage V, is six times the power supply frequency.DC It is known that the disturbance frequency, which is the pulsation frequency of the DC bus voltage V, is twice the power supply frequency. Furthermore, harmonic pulsations occur at frequencies that are integer multiples of these. DC The pulsation of the motor current causes pulsation.

[0036] When viewed from the dq axis current, the frequency of this current pulsation coincides with the disturbance frequency and an integer multiple of the disturbance frequency. When this current pulsation is observed on the three-phase coordinate system, it is found that the disturbance frequency f dis and the frequency f of the phase current of AC motor 1 e The sum and difference frequencies |f dis ±f e This current pulsation has a frequency |f dis -f e This is more likely to become apparent when | is small.

[0037] DC bus voltage V DC This low frequency (disturbance frequency f dis ) phase current pulsation is called beat vibration, and various countermeasures have long been considered. When beat vibration causes phase current pulsation, it can have disadvantages such as a decrease in motor efficiency due to an increase in current peak value, a decrease in maximum output of AC motor 1 due to restrictions on overcurrent protection, and an increase in vibration or noise from AC motor 1.

[0038] The drive unit 4 of the first embodiment automatically minimizes beat vibration to suppress pulsation of the motor current. By manipulating the voltage phase, the drive unit 4 minimizes beat vibration even in the voltage saturation region of the inverter voltage, where the amplitude of the voltage command cannot be manipulated.

[0039] Fig. 2 is a diagram for explaining beat vibration when the driving device according to the first embodiment does not perform voltage phase manipulation, and Fig. 3 is a diagram for explaining the principle by which the driving device according to the first embodiment suppresses beat vibration by voltage phase manipulation.

[0040] The horizontal axis of the graphs shown in Figures 2 and 3 is the d axis, and the vertical axis is the q axis. In Figures 2 and 3, the voltage output by the driving device 4 on average is (v d0 ,v q0 ) and the average output current is (i d0 ,i q0 ) is shown. That is, on average, the drive unit 4 d0 and v q0 The AC motor 1 outputs a voltage of i d0 and i q0 is flowing.

[0041] When the inverter voltage, which is the voltage of the inverter 11, is saturated, the inverter voltage is DC The pulsation (disturbance voltage VD) of the d-axis current (i d0 ,i q0 ) is an elliptical locus centered on the point ∧. In other words, the current locus Ita, which is the locus of the dq-axis current, is an elliptical locus. The larger the elliptical current locus Ita of the dq-axis current, the larger the beat oscillation that appears in the phase current.

[0042] In the first embodiment, the driving device 4 cannot manipulate the amplitude of the voltage command in the voltage saturation region of the inverter voltage, and therefore manipulates the voltage phase to reduce beat vibration.

[0043] It is generally known that if the voltage phase is appropriately changed with respect to the dq-axis voltage command, the elliptical locus of the dq-axis current will become smaller. Various types of beatless control of this type of voltage phase manipulation have been studied, but what kind of voltage phase change (the manipulated variable θ of the voltage phase) is needed to efficiently reduce the elliptical current locus Ita of the dq-axis current? b ) should be given.

[0044] By appropriately changing the voltage phase, the driver 4 efficiently reduces the elliptical current locus Itb of the dq-axis current, as shown in Fig. 3. Fig. 3 shows a case where the driver 4 changes the voltage phase by a phase change amount Pc, so that the voltage locus of the driver 4 becomes the voltage locus Vt and the elliptical current locus of the dq-axis current becomes the current locus Itb.

[0045] Furthermore, in order to enhance the effect of beatless control, the drive device 4 drives the AC motor 1 so that the major and minor axis directions of the elliptical current locus Itb of the dq-axis currents are at an angle desired by the user.

[0046] In the first embodiment, the beatless control unit 18 is configured as shown in FIG. 7, which will be described later, so that the drive unit 4 reduces the elliptical current locus Itb of the dq-axis current and sets the long and short axis directions to the desired angle set by the user.

[0047] Here, a method for efficiently reducing the locus of the dq-axis current ellipse will be described in more detail. Fig. 4 is an equivalent block diagram of a first example of an AC motor driven by the drive device according to the first embodiment. Fig. 5 is an equivalent block diagram of a second example of an AC motor driven by the drive device according to the first embodiment.

[0048] 4 and 5 show equivalent block diagrams in the case where the AC motor 1 is a permanent magnet synchronous motor. For convenience of explanation, the AC motor 1 will be described as a permanent magnet synchronous motor, but the AC motor 1 may be other types of motors such as an induction motor or a synchronous reluctance motor. The AC motor 1 corresponding to the equivalent block diagrams of the first and second examples shown in FIGS. 4 and 5 is * d and q-axis voltage command v * q For d-axis current i d and q-axis current i q Generates.

[0049] The equivalent block diagram shown in Figure 4 is a commonly known equivalent block diagram, where s is the Laplace operator, and the electrical angular velocity ω e When AC motor 1 is driven with a constant current, the input voltage-output current characteristics of the permanent magnet synchronous motor on the dq coordinates can be described by a very simple block diagram.

[0050] As shown in FIG. 4, the equivalent block diagram of the first example of the AC motor 1 has two first-order lag filters 21A and 21B, two electrical reaction parts 22A and 22B, and two action parts 23A and 23B.

[0051] The electrical reaction section 22A converts the d-axis current i output from the first-order lag filter 21A into d Electrical reaction ω against e L d i d to the action unit 23B. The electrical reaction unit 22B outputs the q-axis current i output from the first-order lag filter 21B. q Electrical reaction ω against e L q i q is output to the action unit 23A.

[0052] The action unit 23A receives the d-axis voltage command v from the driving device 4. * d and ω output by the electrical reaction unit 22B e L q i q The action unit 23B outputs the sum of the q-axis voltage command v received from the driving device 4 to the first-order lag filter 21A. * q ω output from the electrical reaction unit 22A e L d i d and the speed electromotive force ω e Φ a The command obtained by subtracting the speed electromotive force ω is sent to the first-order lag filter 21B. e Φ a is the electromotive force induced when the rotor rotates.

[0053] The first-order lag filter 21A generates a d-axis current i according to the action result sent from the action unit 23A. d This d-axis current i d is sent to the electrical reaction section 22A. The first-order lag filter 21B generates a q-axis current i q This q-axis current i q is sent to the electrical reaction section 22B.

[0054] electrical angular velocity ω e When AC motor 1 is driven with a constant current, the equivalent block diagram of the permanent magnet synchronous motor can be approximated to a linear system. Based on this approximation, the equivalent block diagram of Figure 4 can be transformed to obtain the equivalent block diagram of Figure 5.

[0055] As shown in FIG. 5, the equivalent block diagram of the second example of the AC motor 1 has four second-order transfer functions (second-order lag blocks) 24A, 24B, 25A, and 25B, and action parts 26, 27A, and 27B.

[0056] The second-order transfer function 24A is the d-axis voltage command v * d is converted into a d-axis current and output to the action part 27A. Also, the second-order transfer function 25A converts the d-axis voltage command v * d is converted into a q-axis current and output to the action part 27B.

[0057] The action unit 26 is a q-axis voltage command v * q From the speed electromotive force ω e Φ a and outputs the calculation result to secondary transfer functions 24B and 25B. Secondary transfer function 24B converts the calculation result sent from action unit 26 into a q-axis current and outputs it to action unit 27B. Furthermore, secondary transfer function 25B converts the calculation result sent from action unit 26 into a d-axis current and outputs it to action unit 27A.

[0058] The action part 27A adds the d-axis currents sent from the secondary transfer function 24A and the secondary transfer function 25B, and outputs the resulting d-axis current i d The action unit 27B adds the q-axis currents sent from the second-order transfer function 24B and the second-order transfer function 25A, and outputs the q-axis current i q Output.

[0059] 6 is a diagram illustrating an example of a Bode diagram from d-axis voltage to d-axis current of the AC motor driven by the drive device according to the first embodiment. The Bode diagram of the transfer function from the d-axis voltage to the d-axis current is a Bode diagram of secondary transfer functions 24A, 24B, 25A, and 25B. Specifically, the Bode diagram of the transfer function from the d-axis voltage to the d-axis current includes a Bode diagram of secondary transfer function 25A from the d-axis voltage to the q-axis current, a Bode diagram of secondary transfer function 24A from the d-axis voltage to the d-axis current, a Bode diagram of secondary transfer function 24B from the q-axis voltage to the q-axis current, and a Bode diagram of secondary transfer function 25B from the q-axis voltage to the d-axis current. That is, the Bode diagram of the transfer function from the d-axis voltage to the d-axis current of the AC motor 1 includes a Bode diagram of the d-axis voltage command v * d From the q-axis current i q and the d-axis voltage command v * d From d-axis current i d and the q-axis voltage command v * q From the q-axis current i q and the q-axis voltage command v * q From d-axis current i d Here, the d-axis voltage (d-axis voltage command v * d ) to the q-axis current (q-axis current i q ) is explained.

[0060] The horizontal axis of the upper and lower graphs in Fig. 6 is frequency. The vertical axis of the upper graph in Fig. 6 is gain, and the vertical axis of the lower graph is phase. Fig. 6 shows three gain characteristics g1, g2, and g3 and three phase characteristics p1, p2, and p3.

[0061] The Bode diagram of AC motor 1 shows the electrical angular velocity ω e Here, the gain characteristic at low rotation speed is represented by gain characteristic g1, and the phase characteristic is represented by phase characteristic p1. If the rotation speed increases further from this state, the disturbance angular frequency 2πf dis and electrical angular velocity ω e The gain characteristic when the rotation speeds approach each other is represented by gain characteristic g2, and the phase characteristic is represented by phase characteristic p2. When the rotation speed increases further from this state, the gain characteristic is represented by gain characteristic g3, and the phase characteristic is represented by phase characteristic p3.

[0062] The second-order transfer function 24A from the d-axis voltage to the q-axis current has a resonance point, and the resonance angular frequency is the electrical angular velocity ω e The disturbance angular frequency is 2πf dis and electrical angular velocity ω e When the d-axis voltage and q-axis current approach each other, the impedance of the AC motor 1 appears to decrease due to this resonance characteristic, making the motor more susceptible to disturbances. This causes beat vibration. The Bode diagram of the second-order transfer function 25A from the d-axis voltage to the q-axis current varies significantly depending on the rotation speed. In particular, the phase characteristic changes rapidly from +180 degrees to -180 degrees.

[0063] FIG. 6 shows a Bode diagram of the transfer function from the d-axis voltage to the q-axis current. Since the four second-order transfer functions 24A, 24B, 25A, and 25B shown in FIG. 5 have the same denominator polynomial, the other three second-order transfer functions 24A, 24B, and 25B also have similar resonance characteristics.

[0064] In recent years, there have been an increasing number of cases where the DC reactor 8 or the capacitor 9 has been made smaller in capacity. In such a situation, the DC bus voltage V DC is large and prone to pulsation, so the disturbance angular frequency is 2πf dis and electrical angular velocity ω e Even if the d-axis and q-axis currents are far apart, large pulsations tend to appear in the d-axis and q-axis currents. dis and the frequency f of the phase current of AC motor 1 e The difference frequency between |fdis -f e There is a demand for beatless control that operates reliably even under conditions with large |

[0065] However, in conventional beatless control, the disturbance angular frequency is 2πf dis and electrical angular velocity ω e It was adjusted on the assumption that it would operate in a state where the disturbance angular frequency 2πf dis and electrical angular velocity ω e When the voltages are far apart, it becomes difficult to achieve the intended stable operation. This is because, as shown in Fig. 6, the phase characteristics (plant phase) of the AC motor 1 change significantly, which makes it easy for the manipulation of the voltage phase shown in Fig. 3 to have an adverse effect.

[0066] As described above, existing beatless control, which does not consider changes in plant characteristics (plant information) that accompany increases in rotation speed, has the drawback of reducing the control effect as the rotation speed changes. On the other hand, the drive unit 4 of the first embodiment considers changes in plant characteristics that accompany increases in rotation speed, thereby ensuring the effectiveness of beatless control over a wide range of operating conditions.

[0067] 7 is a diagram showing the configuration of a beatless control unit provided in the driving device according to the first embodiment. The beatless control unit 18 has a norm calculation unit 101, a weighting coefficient setting unit 102, a pulsation extraction unit 103, a pulsation suppression unit 104, and a plant information calculation unit 107. The norm calculation unit 101 receives the dq-axis current vector I dq is input to the pulsation extraction unit 103 and the pulsation suppression unit 104, and the disturbance frequency f dis The plant information calculation unit 107 also receives a speed command ω from a host program used by a host device of the driving device 4. * e is entered.

[0068] The norm calculation unit 101 calculates the dq-axis current vector I dq The beatless control unit 18 calculates the norm (absolute value) or weighted norm of the dq-axis current vector Idq The weighting coefficient setting unit 102 is required to calculate the weighted norm of the dq-axis current vector I dq When calculating the norm (when not calculating a weighted norm), the weighting coefficient setting unit 102 may not be provided. The weighting coefficient setting unit 102 stores weighting coefficients w1 and w2 (to be described later) set by the user, and sets the weighting coefficients w1 and w2 in the norm calculation unit 101.

[0069] The weighting coefficient w1 is the weight for the d-axis current, and the weighting coefficient w2 is the weight for the q-axis current. The weights for the d-axis current and the q-axis current are adjusted depending on the ratio of the weighting coefficients w1 and w2. There are various types of norms, but the most well-known norm is the L2 norm, which is calculated using the following equation (1).

[0070]

number

[0071] However, i in equation (1) d and i q are the d-axis current and the q-axis current. The norm calculation unit 101 calculates the norm |I dq Calculate |2. |I dq |2 is the dq axis current vector I dq It should be noted that the norm calculation unit 101 may use an L1 norm, an L∞ norm, or the like instead of the L2 norm.

[0072] Furthermore, the norm calculation unit 101 calculates the weighted norm |I dqw In this case, the norm calculation unit 101 may calculate |I dqw Calculate |.

[0073]

number

[0074] The weighting coefficients w1 and w2 in equation (2) are set to any value equal to or greater than zero. d 2 and i q 2 Instead of i d 3 and i q 3 may be applied, and i d 4 and i q 4 etc. may be applied. dq |2 is |I when w1=w2=1 dqw In FIG. 4, the norm calculation unit 101 is equal to |I dqw 10 shows the configuration of the beatless control unit 18 when calculating | and outputting it to the pulsation extraction unit 103.

[0075] The beatless control unit 18 of the first embodiment calculates the norm (|I dq |2 or |I dqw The effect obtained by beatless control varies depending on the norm of the pulsation component that the beatless control unit 18 suppresses.

[0076] For example, when it is desired to suppress the peak value of the phase current, the beatless control unit 18 dq The beatless control unit 18 suppresses the pulsation of the q-axis current by setting w1 = 0 and w2 = 1. When suppressing vibration and noise of the AC motor 1, the beatless control unit 18 may set w1 = 0 and w2 = 1 to suppress the pulsation of the q-axis current. When aiming for an intermediate state between these two, the beatless control unit 18 may change the weighting factors w1 and w2, such as w1 = 0.5 and w2 = 0.5. The beatless control unit 18 may change the weighting factors w1 and w2, such as w1 = 0.25 and w2 = 0.75, or may change the weighting factors w1 and w2, such as w1 = 0.75 and w2 = 0.25. When the d-axis current is larger than the q-axis current, the beatless control unit 18 may set w1 = 1 and w2 = 0 to suppress the pulsation of the d-axis current.

[0077] The calculation in the norm calculation unit 101 is a calculation for adjusting the long and short axis directions of the elliptical current locus Itb of the dq axis current to the angle desired by the user, and is a calculation for making beatless control work effectively.

[0078] The weighting coefficient setting unit 102 sets the weighting coefficients w1 and w2 according to the purpose of beatless control (what control effect is desired to be obtained by beatless control). The weighting coefficients w1 and w2 may be arbitrarily set by the user of the drive device 4. Note that, although an unweighted norm will be described below, the norm may also be a weighted norm. Note that the weighting coefficient setting unit 102 sets the weighting coefficients w1 and w2 according to the purpose of beatless control (what control effect is desired to be obtained by beatless control). The weighting coefficients w1 and w2 may be arbitrarily set by the user of the drive device 4. Note that, although an unweighted norm will be described below, the norm may also be a weighted norm. dq The weighting factors w1 and w2 may be adjusted based on the rotation speed of the AC motor 1 or the like.

[0079] The pulsation extraction unit 103 extracts the norm (unweighted norm |I dqw | or weighted norm |I dqw The frequency components extracted by the pulsation extractor 103 at this time are the disturbance frequency (fundamental frequency) f dis components and disturbance frequency f dis The pulsation extracting unit 103 may extract the pulsation component of the norm by any extraction method.

[0080] The pulsation extraction unit 103 extracts the norm pulsation component by separating the sine component and the cosine component of the norm pulsation using, for example, the principle of Fourier series. Alternatively, the pulsation extraction unit 103 may extract the pulsation component using a band-pass filter. The following describes a case where the pulsation extraction unit 103 extracts the norm pulsation component using the principle of Fourier series.

[0081] Here, the sin and cos components of the norm pulsation extracted by the pulsation extraction unit 103 are respectively expressed as y sin , y cos The pulsation extraction unit 103 extracts y sin , y cos is output to the pulsation suppression unit 104.

[0082] The plant information calculation unit 107 calculates the speed command ω * e The plant phase, which is the phase characteristic of the plant, is calculated as plant information from the above. The manipulated variable θ, which is the phase change amount of beatless control, is calculated as follows: b from the dq axis current vector I dq The transfer function for the pulsation of the norm or weighted norm is often nonlinear. This transfer function can sometimes be approximated by a very simple linear transfer function by making some assumptions.

[0083] Here, as an example, |v q * |≫|v d * Under the condition of |, we will explain the case where w1=0 and w2=1 are set and we want to suppress the pulsation of the q-axis current. q * |≫|v d * When the voltage phase is manipulated under the condition of |v d * The voltage change of | is |v q * Therefore, the voltage change caused by manipulating the voltage phase occurs mainly in the d-axis direction.

[0084] Which of the four second-order transfer functions 24A, 24B, 25A, and 25B shown in FIG. 5 is important for control depends on the case. In the above case, since we want to suppress the pulsation of the q-axis current by changing the voltage in the d-axis direction, what is important for control is the transfer characteristic from the d-axis voltage to the q-axis current (second-order transfer function 25A). Therefore, focusing on the transfer characteristic from the d-axis voltage to the q-axis current, the manipulated variable θ b from the dq axis current vector I dq Consider the frequency transfer function of the weighted norm of ripple. If we assume that the inverter voltage is saturated and the output voltage amplitude is roughly constant, we obtain the following equation (3).

[0085]

number

[0086] where j is an imaginary number, ω is the angular frequency of the input / output signal, and R a is the armature resistance, and L d is the d-axis inductance, and L q is the q-axis inductance, and ω e is the electrical angular velocity, and V dc is the DC bus voltage V DC The disturbance angular frequency ω dis =2πf dis The phase characteristic of the plant for the signal ∠G(jω dis ) can be written as the following equation (4).

[0087]

number

[0088] Here, G(jω) is a frequency transfer function, and arctan2 is a four-quadrant arctangent calculation function. From equation (4), the phase characteristic ∠G(jω dis ) is the electrical angular velocity ω e It can be seen that the ω in Eq. (4) e Substituting zero and infinity into , the phase characteristic ∠G(jω dis ) changes in the range of 180 degrees to 0 degrees. dis ) is ω e ≒ω dis The result of a trial calculation using an AC motor 1 for driving a compressor shows that the e ω dis When the phase characteristic ∠G(jω dis) has changed by 140 degrees or more. This phase change is very sudden, so if beatless control is performed without taking this phase change into consideration, it becomes difficult to stably obtain a pulsation suppression effect. For this reason, the driving device 4 of the first embodiment performs beatless control taking into consideration the phase change of the plant of the AC motor 1. That is, the plant information calculation unit 107 calculates the phase characteristic ∠G(jω dis The plant information calculation unit 107 calculates the phase characteristic ∠G(jω dis ) is sent to the pulsation suppression unit 104.

[0089] In addition, |v q * | and |v d * When the ratio of | or the ratio of w1 to w2 changes, the frequency transfer function G(jω) and the phase characteristic ∠G(jω dis ) is a slightly different equation from the above-mentioned equations (3) and (4), but a similar equation can be derived by approximating it near the operating point.

[0090] The pulsation suppressor 104 suppresses the phase characteristic ∠G(jω dis ) and use y sin , y cos The voltage phase control amount θ that reduces b The pulsation suppression unit 104 calculates, for example, the phase characteristic ∠G(jω dis ) and use y sin , y cos The voltage phase control amount θ that minimizes b The specific method of this calculation will be described later. In this way, the driving device 4 of the first embodiment automatically searches for the phase characteristic ∠G(jω dis ) to improve the performance of beatless control.

[0091] The driving device 4 has a phase characteristic ∠G(jω dis ), as well as the plant gain characteristic |G(jω dis )| can be used. Gain characteristic |G(jω disThe use of |)| will be described in detail in the third embodiment below. Hereinafter, information such as the transfer function, frequency transfer function, phase characteristics, and gain characteristics of the plant model including four second-order resonant systems (information used by the driving device 4 to improve the performance of beatless control) will be referred to as plant information. The plant information may include at least one of the transfer function, frequency transfer function, phase characteristics, and gain characteristics of the plant model including four second-order resonant systems.

[0092] Here, the calculation performed by the pulsation suppressor 104 will be described in detail. FIG. 8 is a diagram showing the configuration of the pulsation suppressor provided in the beatless control unit according to the first embodiment. The pulsation suppressor 104 calculates the target value r of the pulsation component. * and the cosine component of the norm, and the target value r of the pulsation component * The difference between the sine component of the norm and the voltage phase control amount θ b Calculate.

[0093] The pulsation suppression unit 104 includes subtractors 201A and 201B, a rotation calculation unit 202, integral control units (integral controllers) 203A and 203B, an AC restoration unit 204, and a rotation amount adjustment unit 205. The integral control unit 203A is a first integral control unit, and the integral control unit 203B is a second integral control unit. The rotation calculation unit 202 may be disposed inside the pulsation extraction unit 103.

[0094] The pulsation suppression unit 104 receives a target value r of the pulsation component stored in advance. * and y, which is the cosine component of the pulsation of the norm or weighted norm cos , and the sin component y sin and the disturbance frequency f dis Usually, the target value of the pulsating component r * is set to zero, but the target value of the pulsating component r * may be a non-zero value.

[0095] The subtractor 201A calculates the target value r of the pulsating component. * and y, which is the cosine component of the pulsation of the norm or weighted norm cosThe difference between the two is calculated, and the calculation result is the cosine component deviation e cos to the rotation calculation unit 202.

[0096] The subtractor 201B calculates the target value r of the pulsating component. * and y, the sin component of the pulsation of the norm or weighted norm sin The difference between these is calculated, and the calculation result is the deviation e of the sine component. sin to the rotation calculation unit 202.

[0097] The rotation calculation unit 202 cos and, e sin The rotation calculation is performed using the following equation (5). Here, the cosine component after the rotation calculation is e Rcos The sin component after the rotation is e Rsin That's what they say.

[0098]

number

[0099] θ in Equation (5) R is the rotation amount of the rotation calculation. The rotation amount adjustment unit 205 adjusts the phase characteristic ∠G(jω dis ) to calculate the rotation amount θ R The rotation amount adjustment unit 205 determines the rotation amount θ R is output to the rotation calculation unit 202.

[0100] The rotation calculation unit 202 receives the rotation amount θ from the rotation amount adjustment unit 205. R The rotation calculation unit 202 receives the rotation amount θ received from the rotation amount adjustment unit 205. R Using e cos and e sin A rotation operation is performed on and .

[0101] The integral control unit 203A calculates y cos The deviation e corresponding to Rcos (the rotated cosine component), and the integral control unit 203B integrates y sin The deviation e corresponding to RsinThat is, the integral control unit 203A integrates e Rcos By performing integral control over x cos The integral control unit 203B determines e Rsin By performing integral control over x sin Determine x cos , x sin are the cosine and sin components of the output signal of the beatless control, respectively. * The error between the actual value and the voltage phase is accumulated, and the amount proportional to this accumulated value is used as the voltage phase control amount θ b Integral control is performed by adding

[0102] The integral control unit 203A calculates the rotated cos component e Rcos In other words, the integral control section 203A performs integral control so that the target value r of the pulsating component becomes zero. * and y, which is the cosine component of the pulsation of the norm or weighted norm cos deviation e cos so that e Rcos From x cos That is, the integral control unit 203A determines y cos is the target value of the pulsating component r * By integrally controlling the x cos Determine.

[0103] Furthermore, integral control section 203B converts the rotated sine component e Rsin In other words, the integral control section 203B performs integral control so that the target value r of the pulsating component becomes zero. * and y, the sin component of the pulsation of the norm or weighted norm sin deviation e sin so that e Rsin From x sin That is, the integral control unit 203B determines y sin is the target value of the pulsating component r * By integrally controlling the x sin Determine.

[0104] Although the pulsation suppression unit 104 uses integral control units 203A and 203B here, other control units may be used for the pulsation suppression unit 104. For example, the pulsation suppression unit 104 may use a control unit that performs P (Proportional) control, a control unit that performs PI (Proportional-Integral) control, or a control unit that performs PID (Proportional-Integral-Differential) control.

[0105] The AC restoration unit 204 converts the output of the integral control into AC and outputs a manipulated variable θ b That is, the AC restoration unit 204 determines x cos , x sin , and f dis Based on this, the voltage phase control amount θ b Calculate the following.

[0106] Here, the manipulated variable θ of the voltage phase to be optimized is b First, let us consider the calculation formula for f dis The result of converting this to angular frequency is the disturbance angular frequency ω dis Let ω dis and f dis The relational expression is the following equation (6).

[0107]

number

[0108] Here, as shown in the following equation (7), ω dis The integral result of integrating over time t is θ dis We will represent this with the symbol

[0109]

number

[0110] where f dis can be considered as a constant, so θ discan be expressed as a linear function of time t. At this time, the voltage phase control amount θ b can be expressed as the following equation (8), for example.

[0111]

number

[0112] In equation (8), x cos , x sin are the cosine and sin components of the output signal of the beatless control, respectively. The AC restoration unit 204 adds x cos , x sin , and f dis By applying this, the voltage phase control amount θ b Calculate f in equations (6) to (8). dis By applying dis The sine and cosine waves corresponding to f are derived. dis The corresponding control variable θ b is derived.

[0113] 9 is a diagram illustrating the configuration of a rotation amount adjustment unit included in the beatless control unit according to the first embodiment. The rotation amount adjustment unit 205 according to the first embodiment includes an adder 309. The adder 309 calculates the rotation amount θ by adding a pre-stored default value (for example, 90 degrees) to the plant phase sent from the plant information calculation unit 107. R The adder 309 determines the rotation amount θ R to the rotation calculation unit 202. This allows the beatless control unit 18 to reflect the plant information in the beatless control. The default value may be a value determined for any reason. The default value is, for example, an empirical value (fixed value) estimated from past beatless control.

[0114] Fig. 10 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the first embodiment executes beatless control when the rotation amount is in an optimal state. Fig. 11 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the first embodiment executes beatless control when the rotation amount is in a range of less than ±90 degrees from the optimal value. Fig. 12 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the first embodiment executes beatless control when the rotation amount is away from the optimal value by more than ±90 degrees.

[0115] Rotation amount θ R When the rotation amount θ is within the range of ±90 degrees from the optimum value, R The absolute value of the difference between the rotation amount θ and the optimum value is less than 90 degrees. R When the angle is more than ±90 degrees from the optimum value, the rotation amount θ R and the optimum value is greater than 90 degrees.

[0116] The horizontal axis in Figures 10 to 12 is the cosine component (e cos ) and the vertical axis is the sin component (e sin 10 to 12, when the beatless control unit 18 executes beatless control, e cos and e sin The deviation vector E (not shown) is a motion pattern of the deviation vector E (not shown) which is composed of the deviation vector locus Et. The deviation vector E is a vector from the origin (e cos ,e sin ) is a vector pointing towards the beatless control unit 18. cos ,e sin ) approaches the origin, i.e., the absolute value of the deviation vector E becomes smaller. The deviation vector locus Et has a starting point "Start" and an end point "Goal". When integral control is included within the beatless control, the operation pattern of the deviation vector E under beatless control (deviation vector locus Et corresponding to the behavior of the control unit 400) is R They can be broadly classified into four types depending on the

[0117] The first operation pattern shown in FIG. 10 is a rotation amount θ R When the beatless control unit 18 starts beatless control in this state, e cos and e sin The deviation vector E, which is composed of the above, approaches the origin in the shortest distance due to the action of integral control.

[0118] The second operation pattern shown in FIG. 11 is a rotational movement pattern. R is within a range of less than ±90 degrees from the optimum value. If the beatless control unit 18 starts beatless control at this time, the deviation vector E approaches the origin while drawing a spiral.

[0119] The third operation pattern shown in FIG. 12 is a rotational movement pattern. R is deviated from the optimum value by more than ±90 degrees. If the beatless control unit 18 starts beatless control at this time, the deviation vector E moves away from the origin while drawing a spiral.

[0120] The fourth operation pattern (not shown) is R is in the worst state (a state where it is 180 degrees away from the optimum value). If the beatless control unit 18 starts beatless control at this time, the deviation vector E moves away from the origin in a straight line.

[0121] As described above, the pulsation suppressor 104 is configured to suppress the rotation by an appropriate amount of rotation θ R is given, the deviation e cos and deviation e sin can be controlled to zero, but the rotation amount θ R If is inappropriate, the deviation e cos and deviation e sin Therefore, the beatless control unit 18 according to the first embodiment uses the plant information to calculate the rotation amount θ R This allows the drive unit 4 to expand the range of stable operation compared to conventional beatless control that does not use plant information.

[0122] Typically, the target value of the pulsating component is r * is set to zero, so the deviation e cos ,e sin becomes zero, the cosine component of the pulsation of the dq axis current norm or weighted norm, y cos , and the sin component y sin also becomes zero.

[0123] If the integral control sections 203A and 203B are not provided in the beatless control section 18 (for example, if the beatless control section 18 executes P control), the beatless control section 18 does not calculate the deviation e cos ,e sin However, even in this case, the voltage phase control variable θ b By varying the value of the parameter, the possibility of improving the effect of beatless control can be increased.

[0124] The reason why the first embodiment aims to minimize the ripple of the norm or weighted norm is that minimization is best achieved in the voltage saturation region of the inverter voltage (inverter overmodulation region). DC When the voltage pulsates, pulsation occurs in both the d-axis and q-axis currents. To simultaneously suppress both the d-axis and q-axis current pulsations, both the amplitude and phase of the voltage must be manipulated. This is self-evident from the perspective of control freedom. In a state where only the voltage phase can be controlled, such as in the case of inverter overmodulation, the control unit 400 can control only one parameter. Therefore, under such circumstances, the control unit 400 aims to minimize the pulsation of the norm or weighted norm by controlling the voltage phase.

[0125] In this way, the control unit 400 minimizes the pulsation of the arbitrary norm or weighted norm by appropriately manipulating the voltage phase. However, the control unit 400 uses integral control to obtain the optimal voltage phase manipulated variable θ b 12, the control divergence may occur. Therefore, the control unit 400 of the first embodiment determines whether the plant phase is greater than the electrical angular velocity ωe The optimum voltage phase control amount θ b has been decided.

[0126] This allows the control unit 400 to accurately suppress pulsation in the phase current due to beat vibration under various operating conditions. Note that the effectiveness of beatless control varies depending on the type of pulsation to be reduced. By suppressing pulsation in the phase current, the control unit 400 can prevent, for example, a deterioration in motor efficiency due to an increase in the current peak value, a decrease in the maximum output of the AC motor 1 due to restrictions on overcurrent protection, and an increase in vibration and noise of the AC motor 1.

[0127] 13 is a flowchart illustrating a procedure of a control process executed by the control unit of the driving device according to the first embodiment. The control unit 400 detects the phase current (phase current vector I) flowing through the AC motor 1 detected by the current detection unit 12. uvw ) from the current detection unit 12 (step S10). Next, the control unit 400 acquires the DC bus voltage V DC is acquired from the DC bus voltage detection unit 10 (step S20).

[0128] Thereafter, the coordinate conversion unit 17 performs a coordinate conversion calculation of the current (step S30). That is, the coordinate conversion unit 17 converts the phase current vector I uvw The estimated magnetic pole position θ^ e Using the dq axis current vector I dq Transform the coordinates to

[0129] The rotor position calculation unit 14 calculates the rotor position (step S40). As a result, the rotor position calculation unit 14 acquires position information and rotor speed information of the rotor of the AC motor 1. Specifically, the rotor position calculation unit 14 calculates the dq-axis voltage command vector V * dq and the dq-axis current vector I dq From this, the estimated magnetic pole position θ^, which is the rotor position information, is eand the estimated angular velocity ω^, which is the rotor speed information. e It is estimated that:

[0130] The voltage command determination unit 15 calculates a voltage command for rotating the AC motor 1 at a desired speed and torque (step S50). Specifically, the voltage command determination unit 15 calculates a voltage command for rotating the AC motor 1 at a desired speed and torque (step S50). Specifically, the voltage command determination unit 15 calculates a speed command ω * e and the estimated angular velocity ω^ e The dq-axis current vector I dq to the dq-axis voltage command vector V * dq Calculate the following.

[0131] The beatless control unit 18 executes beatless control calculation (step S60). As a result, the beatless control unit 18 calculates the manipulated variable θ of the voltage phase. b Specifically, the beatless control unit 18 determines the dq-axis current vector I dq The disturbance frequency f included in dis The voltage phase control amount θ is used to reduce the extracted component. b Determine.

[0132] The coordinate conversion unit 16 converts the voltage command into a value on the three-phase coordinate system (step S70). Specifically, the coordinate conversion unit 16 converts the voltage phase manipulated variable θ b and estimated magnetic pole position θ^ e The phase angle θ^ is the sum of eb Using the dq-axis voltage command vector V * dq is the three-phase voltage command vector V * uvw Convert to.

[0133] The modulation unit 13 performs a modulation calculation (step S80). Specifically, the modulation unit 13 modulates the DC bus voltage V DC and three-phase voltage command vector V * uvw The modulation unit 13 determines a PWM signal based on the above.

[0134] Next, a description will be given of the operation of the beatless control unit 18. Fig. 14 is a flowchart showing the procedure of beatless control processing executed by the beatless control unit of the driving device according to the first embodiment.

[0135] In the beatless control unit 18, the weighting coefficient setting unit 102 sets the pre-stored weighting coefficients w1 and w2 in the norm calculation unit 101 (step S110). The norm calculation unit 101 executes a norm calculation (step S120). That is, the norm calculation unit 101 calculates the dq-axis current vector I dq Compute the norm or weighted norm of .

[0136] The pulsation extraction unit 103 executes a pulsation extraction calculation of the norm or weighted norm calculated by the norm calculation unit 101 (step S130). That is, the pulsation extraction unit 103 extracts the disturbance frequency f dis components of and f dis The pulsation extraction unit 103 extracts the pulsation components contained in the norm or weighted norm based on the harmonic components that are integer multiples of y. sin , y cos to the pulsation suppression unit 104.

[0137] The plant information calculation unit 107 calculates the plant information (step S140). That is, the plant information calculation unit 107 calculates the dq-axis voltage command vector V * dq and dq-axis current vector I dq The pulsation suppression unit 104 executes a pulsation suppression calculation (step S150). That is, the pulsation suppression unit 104 calculates the operation amount θ of the voltage phase so as to reduce the pulsation component. b Determine (automatic search).

[0138] Next, the operation of the pulsation suppression unit 104 will be described. Fig. 15 is a flowchart showing the procedure of pulsation suppression processing executed by the pulsation suppression unit of the driving device according to the first embodiment. The pulsation suppression unit 104 determines the point at which the pulsation of the norm or weighted norm is minimum by the following procedure.

[0139] The subtractor 201A subtracts the deviation e of the cos component cos The subtractor 201B calculates the deviation e of the sine component. sin (Step S210). The rotation amount adjustment unit 205 calculates the rotation amount θ R (Step S220). The rotation amount adjustment unit 205 adjusts the adjusted rotation amount θ R is set in the rotation calculation unit 202.

[0140] The rotation calculation unit 202 calculates the rotation amount θ R Specifically, the rotation calculation unit 202 performs a vector rotation calculation using e cos and, e sin and the rotation amount θ R By applying this to equation (5), the cosine component after rotation is obtained as e Rcos and the sin component after the rotation operation, e Rsin Calculate and.

[0141] The integral control units 203A and 203B execute integral control calculations (step S240). Specifically, the integral control unit 203A calculates e after the rotation calculation. Rcos By integrating, x, which is the cosine component of the output signal of beatless control, cos The integral control unit 203B determines the value of e after the rotation calculation. Rsin By integrating, x, which is the sine component of the output signal of beatless control, sin Determine.

[0142] The AC restoration unit 204 performs AC restoration calculation (step S250). Specifically, the AC restoration unit 204 adds x to the equations (6) to (8). cos , x sin , and f dis By applying this, the voltage phase control amount θ b The driving device 4 calculates the manipulated variable θ b By driving the AC motor 1 using this, it becomes possible to effectively suppress beat oscillation of the current even if the operating conditions change significantly.

[0143] Next, a description will be given of the hardware configuration of the control unit 400 included in the drive device 4. Fig. 16 is a diagram illustrating an example of a hardware configuration that realizes the control unit included in the drive device according to the first embodiment.

[0144] The control unit 400 is realized by the processor 91, the memory 92, and the peripheral devices 93. In not only the first embodiment but also the other embodiments, the control unit 400 is realized by the processor 91, the memory 92, and the peripheral devices 93.

[0145] Each function of the control unit 400 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a control program and stored in the memory 92. In the processing circuit that realizes the control unit 400, the processor 91 reads and executes the control program stored in the memory 92, thereby realizing each function. This control program may be provided by a computer-readable recording medium on which the control program is recorded, or may be provided by other means such as a communication medium. The control program can also be said to be a program that causes the control unit 400 to execute the processes of steps S10 to S80 in FIG. 13.

[0146] The processor 91 is a CPU (Central Processing Unit, also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration).

[0147] Examples of memory 92 include non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). Furthermore, memory 92 is not limited to these, and may also be a magnetic disk, optical disk, compact disk, minidisc, or DVD (Digital Versatile Disc).

[0148] The peripheral device 93 is, for example, a PWM pulse generating circuit, an analog-to-digital conversion circuit, an encoder counter, etc. The PWM pulse generating circuit is disposed in the modulation unit 13. The PWM pulse generating circuit is used to drive the inverter 11 and the AC-DC converter.

[0149] The analog-to-digital conversion circuit is disposed in the modulation unit 13, the coordinate conversion unit 17, etc. The analog-to-digital conversion circuit converts, for example, the DC bus voltage V DC It is also used to detect the phase current of the AC motor 1.

[0150] The encoder counter is arranged in the rotor position calculation unit 14 when the rotor position is detected by a position sensor arranged in the compressor 3. The encoder counter is used, for example, to acquire rotor position information.

[0151] As described above, according to the first embodiment, the control unit 400 of the driving device 4 determines the manipulated variable θ of the voltage phase so as to minimize the pulsating component based on the plant information. b Therefore, even in the voltage saturation region of the inverter voltage where the amplitude of the voltage command cannot be manipulated, the pulsation can be reduced as intended under various operating conditions. As a result, the control unit 400 can calculate the DC bus voltage V without performing complicated control adjustments. DC This effectively suppresses beat vibrations caused by pulsation.

[0152] Furthermore, the control unit 400 can effectively suppress beat vibration, which allows for the miniaturization and reduction in capacity of the DC reactor 8 and the capacitor 9. This reduces the manufacturing cost of the drive device 4 and improves energy-saving performance.

[0153] Furthermore, by suppressing beat vibration, the control unit 400 can prevent a deterioration in motor efficiency due to an increase in the current peak value, a decrease in the maximum output of the motor due to restrictions on overcurrent protection, and an increase in vibration and noise of the AC motor 1.

[0154] The control unit 400 also determines the voltage phase manipulation amount θ that minimizes the extracted pulsating component. b Calculate the manipulated variable θ b Since the inverter 11 is controlled using the above, it is possible to easily stabilize the effect of reducing current pulsation regardless of the operating conditions and installation conditions of the drive device 4. Therefore, the control unit 400 can effectively suppress beat oscillation of the current even if the operating conditions and installation conditions of the drive device 4 change significantly.

[0155] Embodiment 2 Next, the second embodiment will be described with reference to Figs. 17 to 24. R The optimum value of varies not only depending on the plant information but also on the power supply inductance 6 (the inductance component of the power supply impedance). There are also cases where the AC motor 1 must be driven at an operating point different from the expected operating point. Therefore, in the second embodiment, a method for stabilizing beatless control under various conditions will be described. In the second embodiment, beatless control is stabilized using not only the plant information but also various other information.

[0156] Fig. 17 is a diagram showing the configuration of a pulsation suppression unit provided in a beatless control unit according to embodiment 2. Among the components in Fig. 17, components that achieve the same functions as those of the pulsation suppression unit 104 of embodiment 1 shown in Fig. 8 are assigned the same reference numerals, and redundant explanations will be omitted.

[0157] Compared to the beatless control unit 18 of the first embodiment, the beatless control unit 18 of the second embodiment has a pulsation suppression unit 104A instead of the pulsation suppression unit 104. Compared to the pulsation suppression unit 104 of the first embodiment, the pulsation suppression unit 104A of the second embodiment has a rotation amount adjustment unit 206 instead of the rotation amount adjustment unit 205.

[0158] The pulsation suppressor 104A of the second embodiment differs from the pulsation suppressor 104 of the first embodiment in that the rotation amount adjuster 206 adjusts the deviation e cos , and the deviation of the sin component e sin Using the rotation amount θ R Fix.

[0159] FIG. 18 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the second embodiment executes beatless control. The horizontal axis of FIG. 18 represents the cosine component (e cos ) and the vertical axis is the sin component (e sin ) in the case where the beatless control unit 18 executes beatless control. cos and e sin 10 shows a deviation vector locus Et, which is a motion pattern of a deviation vector E (not shown) composed of the following: The deviation vector locus Et has a starting point "Start" and an end point "Goal".

[0160] The driving device 4 of the second embodiment uses y cos or the sin component of y sin If y is unintentionally increased, this increase is detected. cos and y sin If an unintended increase in is detected, the beatless control is in an abnormal state (rotation amount θ R is in an inappropriate state), and the rotation amount θ R The rotation amount adjustment unit 206 corrects y cos and y sinBy finding a search direction that reduces the deviation vector E, the deviation vector E is finally made to be zero. This allows the driving device 4 to reliably suppress beat vibration under any operating conditions.

[0161] Here, the concept of the search direction corrected by the beatless control unit 18 will be explained. FIG. 19 is a first explanatory diagram for explaining the search direction corrected by the beatless control unit according to the second embodiment. FIG. 20 is a second explanatory diagram for explaining the search direction corrected by the beatless control unit according to the second embodiment. FIG. 21 is a third explanatory diagram for explaining the search direction corrected by the beatless control unit according to the second embodiment. FIG. 22 is a fourth explanatory diagram for explaining the search direction corrected by the beatless control unit according to the second embodiment.

[0162] 19 to 22 show an image of the search direction corrected by the beatless control unit 18. The horizontal axis of FIG. 19 to FIG. 22 represents the cosine component (e cos ,e Rcos ,x cos ) and the vertical axis is the sin component (e sin ,e Rsin ,x sin 19 to 21, compared to FIGS. 10 to 12, a deviation vector locus ERt, which is the movement pattern (locus) of the deviation vector ER (not shown), an output signal locus xt, which is the movement pattern of the output signal vector x (not shown), and a sector-shaped area representing an image of the search direction are added. The deviation vector ER after the rotation operation is a vector resulting from the rotation operation performed by the rotation operation unit 202 on the deviation vector E before the rotation operation. The output signal locus xt is the locus of the output signal vector x of beatless control.

[0163] The deviation vector ER is (e Rcos ,e Rsin ), and the deviation vector E is, as mentioned above, a vector pointing from the origin (e cos ,e sin) Here, a case will be described in which the ideal values ​​of the deviation vector E before the rotation operation and the deviation vector ER after the rotation operation are zero (the origin).

[0164] 19 to 22, the search direction is shown as a sectorial figure (sector area) that mimics the human field of vision. If the center of the sectorial area is the position of the output signal vector x at a certain time, the arc part of the sectorial area is the image of the forward field of vision at that time.

[0165] Specifically, in Fig. 19, the image of the search direction is shown by search direction image SD1, and in Fig. 20, the image of the search direction is shown by search direction images SD2 and SD3. In Fig. 21, the image of the search direction is shown by search direction images SD4, SD5, and SD6, and in Fig. 22, the image of the search direction is shown by search direction images SD7 and SD8.

[0166] The search direction image SD1 shown in FIG. 19 is a rotation amount θ R This is an image of the search direction when the rotation amount θ is the optimal value. R is optimal, the search direction image SD1 does not need to be changed from the start to the end of the search.

[0167] The search direction images SD2 and SD3 shown in Fig. 20 are rotated by the amount of θ R is an appropriate value. Search direction image SD2 is an image of the search direction when the search starts, and search direction image SD3 is an image of the search direction when the search is completed. In other words, search direction image SD3 is a search direction image after a specific time has passed since the start of the search using search direction image SD2.

[0168] The search direction images SD4, SD5, and SD6 shown in Figure 21 are rotated by the amount of θ Ris an image of the search direction when is an inappropriate value. Search direction image SD4 is an image of the search direction when the search starts, search direction image SD5 is an image of the search direction during the search, and search direction image SD6 is an image of the search direction when the search fails. In other words, search direction image SD5 is an image of the search direction after a specific time has passed since the start of the search using search direction image SD4. Search direction image SD6 is an image of the search direction after a specific time has passed since the search using search direction image SD5.

[0169] 19 to 21, the trajectory of the deviation vector E before the rotation calculation when it tries to move from the point of the initial value Es of the deviation vector E to the point (origin) of the ideal value Ei of the deviation vector E is shown as a deviation vector trajectory Et.

[0170] 19 to 21, the trajectory of the deviation vector ER after the rotation calculation when it tries to move from the point of the initial value ERs of the deviation vector ER to the point of the ideal value Ei of the deviation vector ER (origin) is shown as a deviation vector trajectory ERt.

[0171] In addition, in FIG. 22, the rotation amount θ R is inappropriate and the search fails, and the rotation amount θ R After the adjustment, the trajectory of the deviation vector ER when moving from the point of the initial value ERs of the deviation vector ER to the point (origin) of the ideal value Ei of the deviation vector ER is shown as a deviation vector trajectory ERt2.

[0172] Here, if the ideal value of the output signal vector x can be found, it is assumed that the deviation vector E before the rotation operation and the deviation vector ER after the rotation operation can be set to zero. However, the beatless control unit 18 cannot know in advance where the ideal value of the output signal vector x is located in the diagram.

[0173] The beatless control unit 18 can determine whether or not the search for the ideal value of the output signal vector x has been successful only by observing the deviation vectors E and ER. However, the search range of the output signal vector x is limited. That is, the output signal vector x has a searchable range SR, which is the range within which it can be searched. If the ideal value of the output signal vector x is not within the searchable range SR, the deviation vectors E and ER cannot be set to zero. Therefore, the beatless control unit 18 searches for an output signal vector x that minimizes the deviation vectors E and ER within the searchable range SR.

[0174] The initial value xs of the output signal vector x is an arbitrary value, and is often set to zero, but here it is set to a non-zero value for convenience of drawing. The initial values ​​of the deviation vectors E and ER are also set to arbitrary non-zero values. In FIGS. 19 to 21, the initial value of the deviation vector E is indicated by the initial value Es, and the initial value of the deviation vector ER is indicated by the initial value ERs. Note that the initial value ERs of the deviation vector ER may be the same as the initial value Es of the deviation vector E.

[0175] In FIG. 19, the beatless control unit 18 according to the second embodiment controls the rotation amount θ R The figure shows the operating patterns of the deviation vectors E and ER and the output signal vector x when beatless control is performed when is in the optimal state.

[0176] The deviation vector locus Et, which is the locus of the deviation vector E, and the deviation vector locus ERt, which is the locus of the deviation vector ER after the rotation calculation, are different from each other by the rotation amount θ R The phase is different by the amount of rotation θ R When is in an ideal state, the deviation vectors E and ER move in the shortest distance from the initial values ​​Es and ERs toward the ideal value Ei (origin), which is the ideal point of the deviation vectors E and ER. To achieve this, the output signal vector x also needs to move in the shortest distance from the initial value xs toward the ideal value xi, which is the ideal point of the output signal vector x.

[0177] Since the output signal vector x is a vector obtained by integrating the deviation vector ER, if the direction of the deviation vector ER does not match the ideal direction of movement of the output signal vector x, it is impossible for the output signal vector x to move in the shortest distance. In this case, the parameter for adjusting the direction of the deviation vector ER is the rotation amount θ R Therefore, the beatless control unit 18 calculates the rotation amount θ R By optimizing the above, the deviation vectors E and ER can be moved toward the ideal value Ei in the shortest distance.

[0178] Since the output signal vector x moves along the direction of the deviation vector ER as seen from the origin, the direction of the deviation vector ER as seen from the origin can be considered to be the search direction of the output signal vector x. Alternatively, the search direction of beatless control can be said to be the approximate direction of movement of the output signal vector x.

[0179] The sector area (search direction image SD1) shown in Figure 19 is rotated by the amount of θ R is the optimal value. In this case, the ideal value xi of the output signal vector x is on the extension of the search direction, so the search for the ideal value xi of the output signal vector x is successful.

[0180] The sector area (search direction images SD2 and SD3) shown in Fig. 20 is rotated by the amount of θ R is within a range of less than ±90 degrees from the optimal value. In this case, there is a slight deviation between the direction of the ideal value xi of the output signal vector x and the search direction. The beatless control unit 18's internal integral control (integral control by integral control units 203A and 203B) allows for a slight deviation in the search direction, so the beatless control unit 18 can make the deviation vectors E and ER eventually reach the ideal value Ei. However, since the output signal vector x does not move toward the ideal value xi of the output signal vector x in the shortest distance, the deviation vectors E and ER decrease in a spiral manner.

[0181] The sector area (search direction images SD4, SD5, SD6) shown in Figure 21 is rotated by the amount of θR is more than ±90 degrees away from the optimal value. In this case, there is a large deviation between the direction of the ideal value xi of the output signal vector x and the search direction. In this case, even if the beatless control unit 18 changes the output signal vector x, the deviation vector E,ER does not decrease as intended, so the search direction cannot be uniquely determined and the beatless control unit 18 manipulates the output signal vector x so that the deviation vector E,ER points to a point different from the ideal value Ei. As a result, the beatless control unit 18 increases the deviation vector E,ER along a trajectory that draws a spiral, resulting in beatless control failure.

[0182] In Fig. 21, the points of the deviation vectors E and ER when a search failure is detected are indicated by deviation vectors Ef and ERf, respectively. Also, in Fig. 21, the point of the output signal vector x when a search failure is detected is indicated by the reached value xf.

[0183] In the second embodiment, in preparation for the case where the deviation vectors E and ER perform the operation shown in FIG. 21, the beatless control unit 18 is configured to control the rotation amount θ R A search failure detection unit may be provided to detect a failure in searching for the optimal value of . In the operation described in FIG. 21, the cause of the search failure was an inappropriate search direction (in other words, the rotation amount θ R If the search fails, the beatless control unit 18 detects the failure of the search and corrects the search direction, thereby eventually correcting the rotation amount θ R can be successfully searched for the optimal value of

[0184] In Figure 22, the rotation amount θ R 22 shows an operation image in the case where, after a search for the optimal value of θ has failed, the search direction is corrected and the search is performed again. That is, the behavior shown in FIG. 22 shows that when the beatless control unit 18 detects a search failure, the amount of rotation θ R Adjust the rotation amount θ RThis is the behavior when is reset to an appropriate value. In Fig. 22, as in Fig. 21, the points of the deviation vectors E and ER when a search failure is detected are shown as deviation vectors Ef and ERf, respectively.

[0185] In FIG. 22, the rotation amount before correction is the rotation amount Bθ R The corrected rotation amount is indicated by the rotation amount Aθ R In addition, in FIG. 22, the beatless control unit 18 changes the rotation amount Bθ R The search direction image after adjusting is shown as search direction image SD8. R When you adjust the amount of rotation, the amount of rotation Aθ R As a result, the deviation vector ER and the search direction after the rotation calculation change.

[0186] In Figure 22, the rotation amount Bθ R The locus of the output signal vector x after the adjustment is shown as a locus xt2. Also, in FIG. 22, the rotation amount Aθ after the adjustment R The locus of the deviation vector ER rotated by the rotation calculation is shown as a deviation vector locus ERt2. R The locus of the deviation vector E rotated by the above calculation is shown as a deviation vector locus Et2.

[0187] Suppose the rotation amount Bθ R By adjusting the rotation amount Aθ R When the optimum value is reached, the ideal value xi of the output signal vector x will be on the extension of the search direction, and the search for the optimum value will be completed smoothly.

[0188] In FIG. 22, for convenience of explanation, the rotation amount θ R By adjusting the rotation amount θ R The case where the rotation amount θ R Since the optimal value of is unknown, the rotation amount θ R The adjustment is performed little by little over multiple times by integral control sections 203A and 203B.

[0189] Furthermore, the beatless control unit 18 constantly controls the rotation amount θ during beatless control operation by a method that combines cross product calculation and PID control, which will be described later. R You can continue to modify the rotation amount θ R By the correction process of the deviation vector E, the deviation vector E may approach the origin through a complex deviation vector locus Et as shown in FIG. 18. Also, as shown in FIG. 22, the deviation vector E may approach the origin through a rotation amount θ R After the correction, the deviation vector E may move toward the origin along a linear deviation vector locus Et2.

[0190] In beatless control, it is unknown where the ideal value xi of the output signal vector x is, and if the output signal vector x is manipulated in an inappropriate direction, beat vibration will increase, so the search for the ideal value xi of the output signal vector x must be carried out carefully. For this reason, in the second embodiment, the beatless control unit 18 appropriately corrects the search direction of the beatless control so that the output signal vector x can reliably reach the ideal value xi.

[0191] The rotation amount adjustment unit 206 adjusts the rotation amount θ R The rotation amount adjusting unit 206 may adjust the rotation amount θ by, for example, a method that combines a cross product calculation and PID control, which will be described later. R Furthermore, the rotation amount adjustment unit 206 corrects (adjusts) the rotation amount θ R may be automatically searched for.

[0192] Here, the rotation amount θ RAn example of a method for adjusting the deviation vector will be described below. Fig. 23 is a diagram showing a first behavior of the deviation vector when the beatless control section according to the second embodiment is executing beatless control. Fig. 24 is a diagram showing a second behavior of the deviation vector when the beatless control section according to the second embodiment is executing beatless control. Fig. 25 is a diagram showing a third behavior of the deviation vector when the beatless control section according to the second embodiment is executing beatless control.

[0193] The horizontal axis in Figures 23 to 25 is the cosine component (e cos ) and the vertical axis is the sin component (e sin 23 to 25, the e when the pulsation suppression unit 104A is performing beatless control is cos and e sin The diagram shows the behavior of the deviation vector E.

[0194] The pulsation suppression unit 104A can determine whether beatless control is being performed appropriately by examining the deviation vector E and the time differential vector (d / dt)E of the deviation vector E. Hereinafter, the time differential vector (d / dt)E of the deviation vector E may be referred to as the time differential vector (d / dt)E.

[0195] When the deviation vector E and the time differential vector (d / dt)E are in opposite phases as in the first behavior of the deviation vector E shown in FIG. 23, the pulsation suppression unit 104A determines that beatless control is being performed satisfactorily.

[0196] Furthermore, when the direction of the time differential vector (d / dt)E is inward (toward the origin) from the vertical line of the deviation vector E, as in the second behavior of the deviation vector E shown in Figure 24, the pulsation suppression unit 104A determines that beatless control is being performed appropriately to a certain extent.

[0197] When the direction of the time differential vector (d / dt)E is outward from the vertical line of the deviation vector E, as in the third behavior of the deviation vector E shown in Figure 25, the pulsation suppression unit 104A determines that beatless control is not being performed appropriately.

[0198] If the state of the deviation vector E shown in FIG. 25 is left as it is, the beatless control will become unstable and diverge. Therefore, the pulsation suppressor 104A adjusts the rotation amount θ so that the deviation vector E is in the state shown in FIG. 23 or 24. R Fix.

[0199] As shown in FIG. 24, when the direction of the time differential vector (d / dt)E is inward from the perpendicular line of the deviation vector E, the pulsation suppression unit 104A adjusts the rotation amount θ so that the direction of the time differential vector (d / dt)E faces further inward. R may be corrected.

[0200] The pulsation suppressor 104A rotates by an amount of rotation θ R In order to correct the rotation amount θ , the pulsation suppression unit 104A evaluates whether the beatless control is being performed appropriately using a quantitative numerical value (evaluation value). R Fix.

[0201] 26 is a diagram for explaining an evaluation value used by the pulsation suppression unit according to the second embodiment to evaluate whether beatless control is being performed appropriately. The horizontal axis of FIG. 26 represents the cosine component, and the vertical axis represents the sinusoidal component.

[0202] FIG. 26 shows an example of the definition of the evaluation value. The pulsation suppression unit 104A evaluates the appropriateness of the operation of the beatless control by using, for example, the cross product of the deviation vector E and the time differential vector (d / dt)E of the deviation vector E (the area of ​​the parallelogram formed by the two vectors). Here, the evaluation value for evaluating whether the beatless control is being performed appropriately is defined as C. d The cross product of the deviation vector E and the time derivative vector (d / dt)E of the deviation vector E is C d is.

[0203] The pulsation suppression unit 104A increases the rotation amount θ as the area of ​​the parallelogram formed by the deviation vector E and the time differential vector (d / dt)E of the deviation vector E decreases. RAs a result, the closer the angle between the deviation vector E and the time differential vector (d / dt)E is to 180 degrees or to 0 degrees, the smaller the amount of rotation θ R That is, the closer the angle between the deviation vector E and the time differential vector (d / dt)E is to 90 degrees, the smaller the correction amount of the rotation amount θ R Increase the correction amount.

[0204] 27 is a diagram showing the configuration of a rotation amount adjustment unit included in the pulsation suppression unit according to embodiment 2. The rotation amount adjustment unit 206 according to embodiment 2 includes a cross product calculation unit 300, a dead zone 305, a PID control unit 306, and an adder 309.

[0205] The cross product calculation unit 300 includes pseudo differentiators 302A and 302B, multipliers 303A and 303B, and a subtractor 304. The rotation amount adjustment unit 206 receives the plant phase from the plant information calculation unit 107.

[0206] Note that the symbol s shown in Fig. 27 is a Laplace operator. For the rotation amount adjustment unit 206, a differentiator without a low-pass filter (LPF: Low Pass Filter) may be used instead of the pseudo differentiators 302A and 302B, but Fig. 27 describes a case where the pseudo differentiators 302A and 302B are provided with a low-pass filter to remove differentiation noise.

[0207] The deviation e from the subtractor 201A is input to the cross product calculation unit 300. cos is input, and the deviation e is output from the subtractor 201B. sin is entered.

[0208] The cross product calculation unit 300 calculates the evaluation value C d The cross product calculation unit 300 calculates the deviation e cos is input to the pseudo differentiator 302A and the multiplier 303B, and the deviation e sin is input to pseudo differentiator 302B and multiplier 303A.

[0209] The pseudo differentiator 302A calculates the deviation e cos By differentiating with respect to time t and passing it through a low-pass filter, (d / dt)e cos The multiplier 303A calculates and outputs e sin and (d / dt)e cos and outputs the multiplication result to the subtractor 304.

[0210] The pseudo differentiator 302B calculates the deviation e sin By differentiating with respect to time t and passing it through a low-pass filter, (d / dt)e sin The multiplier 303B calculates and outputs the result to the multiplier 303B. cos and (d / dt)e sin and outputs the multiplication result to the subtractor 304.

[0211] The subtractor 304 subtracts the multiplication result output from the multiplier 303B from the multiplication result output from the multiplier 303A to obtain an evaluation value C d The subtractor 304 calculates C d is output to the dead zone 305.

[0212] The dead zone 305 is the rotation amount θ after the beatless control has converged to the final value. R Stop the adjustment of the rotation amount θ R It is not preferable in terms of the stability of beatless control to adjust the rotation amount θ more than necessary. Therefore, the rotation amount adjustment unit 206 of the second embodiment adjusts the rotation amount θ by the dead band 305 after the beatless control has converged to the final value. R The rotation amount adjustment unit 206 stops adjusting the rotation amount θ R As a mechanism for stopping the adjustment, a circuit other than the dead zone 305 may be used.

[0213] The PID control unit 306 executes PID control on the signal output from the dead zone 305, and calculates the rotation amount θ R is output to the adder 309. Note that the rotation amount θ R The adjustment of the rotation amount θ may be performed using any circuit. RThe adjustment of the rotation amount θ may be performed, for example, by a PI control unit that performs PI control. If better control results can be expected, a different type of control unit or AI may be used to adjust the rotation amount θ R may be adjusted.

[0214] The adder 309 calculates the rotation amount θ R The plant phase transmitted from the plant information calculation unit 107 and a pre-stored default value (for example, 90 degrees) are added to the rotation amount θ R The adder 309 corrects the rotation amount θ R is output to the rotation calculation unit 202.

[0215] In this way, the rotation amount adjustment unit 206 of the second embodiment adjusts the rotation amount θ R is determined by the sum of a default value, the output from the PID control unit 306, and the plant information (plant phase).

[0216] The rotation amount adjustment unit 206 adjusts the rotation amount θ R By changing the value, the beatless control operation is optimized, and the evaluation value C d The evaluation value C decreases. d When decreases to a certain value, the rotation amount θ R At this time, the change in the rotation amount θ R Since is an appropriate value, the deviation vector E will eventually converge to zero.

[0217] Next, a description will be given of the operation of the rotation amount adjustment unit 206. Fig. 28 is a flowchart showing the procedure of the rotation amount adjustment process executed by the rotation amount adjustment unit according to the second embodiment.

[0218] The cross product calculation unit 300 calculates C, which is an evaluation value for determining whether beatless control is being performed appropriately. d That is, the cross product calculation unit 300 calculates the deviation e of the cosine component calculated by the subtractor 201A (step S320). cos and the deviation e calculated by the subtractor 201B. sin Based on this, the evaluation value Cd Calculate the following.

[0219] The dead zone 305 of the rotation amount adjustment unit 206 executes dead zone processing (step S330). The PID control unit 306 of the rotation amount adjustment unit 206 performs PID control calculation (step S340) to obtain the evaluation value C d Rotation amount θ so that R Fix.

[0220] The adder 309 executes the addition process (step S370). Specifically, the adder 309 adds the rotation amount θ R The plant phase transmitted from the plant information calculation unit 107 and a default value (for example, 90 degrees) are added to the rotation amount θ R Adjust.

[0221] As described above, according to the second embodiment, the control unit 400 of the drive unit 4 controls the rotation amount θ R is in an inappropriate state, the inappropriate state is automatically detected and the rotation amount θ R Therefore, the DC bus voltage V DC This effectively suppresses beat vibrations caused by pulsation.

[0222] Furthermore, according to the second embodiment, y cos and y sin When an unintended increase in R Since the above formula is corrected, beat vibration can be reliably suppressed under various operating conditions.

[0223] Embodiment 3 Next, a third embodiment will be described with reference to Figs. 29 and 30. In the beatless control described in the second embodiment, integration is performed, and in the beatless control of the third embodiment, integral control is also performed. If the control gain of integral control is not determined appropriately, the control response will be slow or will become oscillatory. Therefore, it is necessary to determine the control gain appropriately so that the control response will have a desired waveform. In the third embodiment, the control gain is determined using the gain characteristics of the plant.

[0224] Here, as an example, we will explain the case where the beatless control plant can be expressed as the frequency transfer function of equation (3). dis =2πf dis The gain characteristic of the plant for the signal |G(jω dis )| can be written as the following equation (9).

[0225]

number

[0226] From equation (9), the gain characteristic |G(jω dis )| is the electrical angular velocity ω e It can be seen that it changes depending on ω e ≒ω dis In the neighborhood of |G(jω dis )| increases, i.e., ω e and ω dis When the voltages are close to each other, the apparent impedance decreases. Therefore, even a slight change in voltage causes the current of the AC motor 1 to change sensitively.

[0227] On the other hand, ω e and ω dis When and are separated, |G(jω dis )| decreases, i.e., ω e and ω dis If the distance between the terminals is large, the apparent impedance increases. Therefore, unless a large voltage change is applied, the current of the AC motor 1 will not change.

[0228] In this way, the gain characteristic of the beatless control plant is the electrical angular velocity ω e Therefore, if beatless control is performed without taking into account the gain change, it is difficult to stably obtain a pulsation suppression effect. For this reason, in the third embodiment, beatless control is performed taking into account the gain change of the plant.

[0229] Rotation amount θ R When is appropriate, beatless control can be performed at any response angular frequency ω ctrl In order to make the pulsation suppressor 104B respond with the control gain K i can be determined as shown in the following equation (10).

[0230]

number

[0231] As shown in equation (10), the gain characteristic |G(jω dis )|, the control gain K i By increasing or decreasing the value of the parameter , it is possible to prevent the beatless control from becoming slow or oscillating. This also allows the beatless control section 18B to reliably suppress beat vibration under any operating conditions.

[0232] Here, the case where the control unit (controller) included in the pulsation suppression unit 104B is the integral control units 203A and 203B has been described. However, the control unit included in the pulsation suppression unit 104B may be another type of controller, such as a control unit that performs PI control or a control unit that performs PID control. Even in these cases, the gain characteristic |G(jω dis It is possible to design the control gain taking into account the change in |

[0233] In addition, |v q * | and |v d *If the ratio of | or the ratio of w1 to w2 changes, the frequency transfer function G(jω) will be a slightly different formula from equation (3), but if approximation is performed near the operating point, a similar formula can be derived. Therefore, it can be said that the design method for control gains does not change much in other cases.

[0234] 29 is a diagram showing the configuration of a beatless control unit provided in a driving device according to the third embodiment. Compared to the beatless control unit 18 of the first embodiment, the beatless control unit 18B of the third embodiment includes a plant information calculation unit 107B instead of the plant information calculation unit 107. Also, compared to the beatless control unit 18 of the first embodiment, the beatless control unit 18B of the third embodiment includes a pulsation suppression unit 104B instead of the pulsation suppression unit 104.

[0235] The plant information calculation unit 107B calculates a plant phase, which is a phase characteristic of the plant, and a plant gain, which is a gain characteristic of the plant. The plant information calculation unit 107B calculates the plant gain using, for example, equation (9). The plant information calculation unit 107B transmits the plant phase and the plant gain to the pulsation suppression unit 104B.

[0236] 30 is a diagram showing the configuration of a pulsation suppression unit included in the beatless control unit according to embodiment 3. The pulsation suppression unit 104B of embodiment 3 includes a control gain calculation unit 207 in addition to the components included in the pulsation suppression unit 104 of embodiment 1.

[0237] The control gain calculation unit 207 receives the plant gain, which is the gain characteristic of the plant, from the plant information calculation unit 107B. The control gain calculation unit 207 calculates the gain characteristic |G(jω dis )| to the control gain K i The control gain calculation unit 207 calculates the control gain K i are output to integral control sections 203A and 203B.

[0238] The integral control units 203A and 203B calculate the control gain Ki That is, the integral control section 203A operates based on the control gain K i Using deviation e Rcos By integrating x cos The integral control section 203B determines the control gain K i Using deviation e Rsin By integrating x sin Determine.

[0239] As described above, according to the third embodiment, the beatless control unit 18B executes beatless control based on the plant phase and plant gain, and therefore, it is possible to appropriately execute beatless control under a wide range of operating conditions.

[0240] Embodiment 4 Next, a fourth embodiment will be described with reference to Fig. 31. In the fourth embodiment, the driving device 4 described in the first to third embodiments is applied to a refrigeration cycle device.

[0241] Fig. 31 is a diagram showing the configuration of a refrigeration cycle device according to embodiment 4. Among the components in Fig. 31, components that achieve the same functions as the drive device 4 and compressor 3 of embodiment 1 shown in Fig. 1 are assigned the same reference numerals, and redundant explanations will be omitted.

[0242] A refrigeration cycle apparatus 900 of the fourth embodiment has a compressor drive system 800. The compressor drive system 800 includes a drive device 4 having a control unit 400, and a compressor 3 incorporating the AC motor 1 of the first embodiment. The refrigeration cycle apparatus 900 also includes a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, an outdoor heat exchanger 910, and refrigerant piping 912.

[0243] Refrigeration cycle device 900, which is a refrigeration cycle application device, can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, heat pump water heaters, etc. In compressor drive system 800, compressor 3, drive unit 4, four-way valve 902, indoor heat exchanger 906, expansion valve 908, and outdoor heat exchanger 910 are connected via refrigerant piping 912.

[0244] The compressor 3 includes a compression mechanism 904 that compresses the refrigerant and an AC motor 1 that operates the compression mechanism 904. The compression mechanism 904 corresponds to the mechanical device 2 described in the first embodiment. The refrigeration cycle device 900 can perform heating or cooling operation by switching the four-way valve 902. The compression mechanism 904 is driven by the AC motor 1 that is variable speed controlled.

[0245] During heating operation, as shown by the solid arrows, the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910, and the four-way valve 902, and returns to the compression mechanism 904.

[0246] During cooling operation, as indicated by the dashed arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906 and the four-way valve 902 and returns to the compression mechanism 904.

[0247] During heating operation, the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat. The expansion valve 908 decompresses and expands the refrigerant.

[0248] Thus, according to the fourth embodiment, the pulsation can be reduced as intended even in the voltage saturation region of the inverter voltage, and therefore, by suppressing beat vibration, the refrigeration cycle device 900 can prevent deterioration of motor efficiency due to an increase in current peak value, a decrease in maximum motor output due to restrictions on overcurrent protection, and an increase in vibration and noise of the AC motor 1.

[0249] Furthermore, the control unit 400 can effectively suppress beat vibration, which enables the DC reactor 8 and the capacitor 9 to be made smaller and have a smaller capacity. This reduces the manufacturing cost of the refrigeration cycle apparatus 900 and improves the energy-saving performance.

[0250] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0251] 1 AC motor, 2 mechanical device, 3 compressor, 4 drive device, 5 AC power supply, 6 power supply inductance, 7 diode rectifier, 8 DC reactor, 9 capacitor, 10 DC bus voltage detection unit, 11 inverter, 12 current detection unit, 13 modulation unit, 14 rotor position calculation unit, 15 voltage command determination unit, 16, 17 coordinate conversion unit, 18, 18B beatless control unit, 19, 309 adder, 21A, 21B first-order lag filter, 22A, 22B electrical reaction unit, 23A, 23B, 26, 27A, 27B action unit, 24A, 24B, 25A, 25B second-order transfer function, 91 processor, 92 memory, 93 peripheral equipment, 101 norm calculation unit, 102 weighting coefficient setting unit, 103 Pulsation extraction unit, 104, 104A, 104B Pulsation suppression unit, 107, 107B Plant information calculation unit, 201A, 201B, 304 Subtractor, 202 Rotation calculation unit, 203A, 203B Integral control unit, 204 AC restoration unit, 205, 206 Rotation amount adjustment unit, 207 Control gain calculation unit, 300 Cross product calculation unit, 302A, 302B Pseudo differentiator, 303A, 303B Multiplier, 305 Dead band, 306 PID control unit, 400 Control unit, 800 Compressor drive system, 900 Refrigeration cycle device, 902 Four-way valve, 904 Compression mechanism, 906 Indoor heat exchanger, 908 Expansion valve, 910 Outdoor heat exchanger, 912 Refrigerant piping, E, ER Deviation vector, Et, ERt Deviation vector locus, Ita, Itb current locus, Pc phase change amount, VD disturbance voltage, Vt voltage locus, g1, g2, g3 gain characteristics, p1, p2, p3 phase characteristics.

Claims

1. A drive device that drives an AC motor using an inverter, A current detection unit for detecting the current flowing through the AC motor, A rotor position calculation unit calculates rotor position information, which is information about the position of the rotor of the AC motor, A voltage command determination unit determines a voltage command based on the current vector of the current and the rotor position information, A beatless control unit that suppresses the current pulsation caused by periodic pulsation of the DC bus voltage by manipulating the voltage phase of the voltage command, Equipped with, The aforementioned beatless control unit is The plant information calculation unit calculates plant information, which is information about the characteristics of the plant that changes with the change in rotational speed based on the electrical angular velocity of the AC motor, and manipulates the voltage phase based on the plant information and the pulsating component of the norm of the current vector. A drive device characterized by the following features.

2. The aforementioned beatless control unit is A norm calculation unit that calculates the aforementioned norm, A pulsation extraction unit for extracting the pulsation component of the norm, A pulsation suppression unit that determines the amount of voltage phase manipulation that reduces the pulsation component using the plant information, It has, The beatless control unit manipulates the voltage phase using the manipulated amount. The drive device according to feature 1.

3. The pulsation extraction unit separates and extracts the pulsation component of the norm into a cosine component and a sine component. The pulsation suppression unit is, A rotation amount adjustment unit that determines the amount of rotation when performing rotation calculations on the cosine component and the sine component using the plant information, A rotation calculation unit that performs rotation calculations on the cosine component and the sine component using the rotation amount, A first integral control unit that integrates the rotated cosine component, A second integral control unit that integrates the rotated sine component, An AC restoration unit calculates the manipulated variable based on the integrated cosine component, the integrated sine component, and the disturbance frequency which is the pulsation frequency of the DC bus voltage. Equipped with, The drive device according to feature 2.

4. The rotation amount adjustment unit is, When an increase in the cosine component and the sine component is detected, the amount of rotation is corrected. The drive device according to feature 3.

5. The plant information calculation unit calculates the plant phase, which is the phase characteristic of the plant, from the velocity command, which is the command for the angular velocity of the rotor, as plant information. The rotation amount adjustment unit determines the rotation amount using the plant phase. The drive device according to feature 3.

6. The plant information calculation unit calculates the plant gain, which is the gain characteristic of the plant, as the plant information. The rotation amount adjustment unit determines the rotation amount using the plant gain. The drive device according to feature 3.

7. The norm is a weighted norm that is weighted with respect to the d-axis current and the q-axis current. The drive device according to feature 1.

8. A first coordinate transformation unit transforms the three-phase current vector of the current detected by the current detection unit into an axial current vector of a rotating two-phase coordinate system, which is the current vector, based on the rotor position information. A second coordinate transformation unit converts the voltage command, whose voltage phase has been manipulated by the aforementioned manipulated amount, into a three-phase voltage command vector. Furthermore, The voltage command determination unit generates the voltage command of the three-phase voltage command vector based on the axis current vector. The beatless control unit searches for the manipulated variable based on the axial current vector. The drive device according to feature 2.

9. A drive device according to any one of claims 1 to 8, A compressor driven by the aforementioned AC motor, Equipped with, A compressor drive system characterized by the following:

10. The compressor drive system is provided according to claim 9. A refrigeration cycle device characterized by the following features.

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