Drive device, compressor drive system, and refrigeration cycle device

Abstract

A drive device (4) for driving an AC motor (1) by an inverter (11) comprises: a current detection unit (12) for detecting a current flowing through the AC motor; a rotor position calculation unit (14) for calculating rotor position information that is information on the position of the rotor of the AC motor; a voltage command determination unit (15) for determining a voltage command on the basis of a current vector of the current and the rotor position information; and a beatless control unit (18) for suppressing pulsation of the current caused by periodic pulsation of a DC bus voltage by manipulating the voltage phase of the voltage command. The beatless control unit has a norm calculation unit for calculating a norm of the current vector, a pulsation extraction unit for extracting a pulsation component of the norm, and an automatic search unit for searching for a voltage phase manipulation amount at which the pulsation component is minimized. The beatless control unit manipulates the voltage phase using the manipulation amount.

Description

Drive device, compressor drive system, and refrigeration cycle device

[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.

[0002] Drive devices that combine an AC (Alternating Current)-DC (Direct Current) converter and a DC-AC converter (inverter) are widely used to drive AC motors. A capacitor is used in the DC bus section of these drive devices. A reactor is often inserted on the AC-DC converter side for the purposes of power factor improvement and voltage boosting. For these drive devices, miniaturization and reduction in capacity of the capacitor and reactor are being considered in order to reduce costs.

[0003] However, using a small-capacity capacitor or reactor increases the periodic pulsation of the DC bus voltage, adversely affecting 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 maximum motor output due to restrictions on overcurrent protection, and increased vibration and 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 and sin components 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 to correct the dq-axis voltages output to the inverter.

[0006] Patent No. 4988329

[0007] However, the technique of Patent Document 1 has the problem that the desired voltage control cannot be performed in the voltage saturation region of the inverter voltage, and therefore the pulsation cannot be reduced 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.

[0009] To solve the above-mentioned problems and achieve the object, a drive device disclosed herein 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 the rotor of the AC motor. The drive device also includes a voltage command determination unit that determines a voltage command based on a current vector and the rotor position information, and a beatless control unit that suppresses current pulsation caused by periodic pulsation in a DC bus voltage by manipulating the voltage phase of the voltage command. The beatless control unit includes a norm calculation unit that calculates the norm of the current vector, a pulsation extraction unit that extracts the pulsation component of the norm, and an automatic search unit that searches for a manipulated variable for the voltage phase that minimizes the pulsation component. The beatless control unit manipulates the voltage phase using the manipulated variable.

[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.

[0011] FIG. 1 is a diagram showing the configuration of a drive device according to a first embodiment; FIG. 2 is a diagram for explaining beat vibrations when the drive device according to the first embodiment does not perform voltage phase manipulation; FIG. 3 is a diagram for explaining the principle by which the drive device according to the first embodiment suppresses beat vibrations by voltage phase manipulation; FIG. 4 is a diagram showing the configuration of a beatless control unit provided in the drive device according to the first embodiment;FIG. 1 is a diagram showing an operation pattern of a deviation vector when beatless control is executed when the rotation amount is away from the optimal value by more than ±90 degrees. FIG. 2 is a flowchart showing the processing procedure of the automatic search processing executed by the automatic search unit of the drive device according to the second embodiment. FIG. 3 is a diagram showing the configuration of the beatless control unit provided in the drive device according to the third embodiment. FIG. 4 is a diagram showing an operation pattern of a deviation vector when beatless control is executed by the beatless control unit according to the third embodiment. FIG. 1 shows a second behavior of the deviation vector when the beatless control unit according to the third embodiment automatically searches for an operation amount for a voltage phase. FIG. 2 shows a third behavior of the deviation vector when the beatless control unit according to the third embodiment automatically searches for an operation amount for a voltage phase. FIG. 3 shows an evaluation value used by the automatic search unit according to the third embodiment to evaluate whether beatless control is being performed appropriately. FIG. 4 shows the configuration of a rotation amount adjustment unit possessed by the automatic search unit according to the third embodiment. Flowchart showing the processing procedure for rotation amount adjustment processing performed by the rotation amount adjustment unit according to the third embodiment. FIG. 5 shows the configuration of a drive unit according to the fifth embodiment. FIG. 6 shows the configuration of a drive unit according to the sixth embodiment. FIG. 7 shows the configuration of a beatless control unit possessed by the drive unit according to the sixth embodiment.

[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] First Embodiment 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 power source impedance (parasitic impedance) exists between the drive device 4 and the AC power source 5. The power source inductance 6 is the inductance component of the power 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 drive device 4 of embodiment 1 can also be applied when the AC power supply 5 is a single-phase AC power supply.

[0016] The drive 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 the DC reactor 8 is connected to the positive output point of the diode rectifier 7, and the other end of the DC reactor 8 is connected to the positive input point of the inverter 11. In addition, one end of a capacitor 9 is connected to the other end of the DC reactor 8. The other end of the capacitor 9 is connected to the negative output point of the diode rectifier 7 and the negative input point of the inverter 11. The DC reactor 8 and capacitor 9 are provided to smooth the DC power output from the diode rectifier 7.

[0019] The DC bus voltage detector 10 detects the voltage across the capacitor 9 as the DC bus voltage V DC and outputs the detected voltage 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 includes 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 uses a rotating two-phase coordinate system to control the AC motor 1. Here, a case will be described in which the control unit 400 performs control using a dq rotating coordinate system based on the direction of the rotor magnet, but the control unit 400 may also perform control using 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 dq axis current vector I dq From this, the estimated magnetic pole position θ^ e and estimated angular velocity ω^ eIt 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 applied by the inverter 11 to the AC motor 1. The dq-axis voltage command vector V * dq is a 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 θ̂ into e That is, the coordinate transformation unit 17 performs a rotational two-phase transformation based on the estimated magnetic pole position θ̂e, which is rotor position information. The coordinate transformation unit 17 transforms the dq-axis current vector I dqare 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 from the dq axis voltage command vector V * dq The voltage command determination unit 15 determines the d-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 determiner 15 determines the speed command ω * e and the estimated angular velocity ω^ sent from the rotor position calculation unit 14. e The d- and q-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 d-axis and q-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 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 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^ e is 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 Determine 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 The beatless control unit 18 controls the voltage phase of the voltage command to the inverter 11 by outputting the voltage command, 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 manipulated variable θ of the voltage phase 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 disThe rotor pole position is adjusted to suppress the pulsation corresponding to the phase angle θ̂. 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 transformation 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 determines a PWM signal for operating the inverter 11 based on the DC bus voltage V DC and the three-phase voltage command vector V sent from the coordinate conversion unit 16 * uvw The PWM signal is determined based on the above and output to the inverter 11.

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

[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, the disturbance frequency f dis and the frequency f of the phase current of the 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] This low frequency (disturbance frequency f dis The phase current pulsation caused by beat vibration has been called beat vibration, and various countermeasures have been investigated for a long time. When beat vibration causes phase current pulsation, it can cause disadvantages such as a decrease 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 or noise of the 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] 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 average voltage output by the drive unit 4 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 expands and contracts as shown in FIG. 2 due to the pulsation of the DC bus voltage (disturbance voltage VD). As a result, the dq axis currents are (i d0 , i q0 ) is centered on the point (1). That is, the current locus Ita, which is the locus of the d-axis and q-axis currents, is an elliptical locus. The larger the elliptical current locus Ita of the d-axis and q-axis currents, the larger the beat oscillation that appears in the phase currents.

[0042] In the first embodiment, the drive 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 the elliptical locus of the dq-axis currents can be reduced by appropriately changing the voltage phase of the dq-axis voltage command. Various types of beatless control of this type of voltage phase manipulation have been studied, but it is unclear what kind of voltage phase change (the manipulated variable θ of the voltage phase) is required to efficiently reduce the locus of the elliptical current locus Ita of the dq-axis currents. b ) should be given.

[0044] By appropriately changing the voltage phase, the driver 4 efficiently reduces the elliptical current locus Itb of the d-axis and q-axis currents, 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 d-axis and q-axis currents becomes the current locus Itb.

[0045] Furthermore, in order to enhance the effect of beatless control, the drive unit 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. 4 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] 4 is a diagram showing the configuration of a beatless control unit provided in the drive 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, and an automatic search unit 104. The norm calculation unit 101 receives the dq-axis current vector I dq is input to the pulsation extraction unit 103 and the automatic search unit 104, and the disturbance frequency f dis is entered.

[0048] 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 I dq 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 of (when not calculating a weighted norm), the weighting coefficient setting unit 102 does not need to be provided. The weighting coefficient setting unit 102 stores weighting coefficients w1 and w2 (described later) set by the user, and sets the weighting coefficients w1 and w2 in the norm calculation unit 101.

[0049] 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 of 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):

[0050]

[0051] 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 The norm calculation unit 101 may use an L1 norm, an L∞ norm, or the like instead of the L2 norm.

[0052] Furthermore, the norm calculation unit 101 calculates a weighted norm |I using the following equation (2) to which weighting factors w1 and w2 are applied. dqw In this case, the norm calculation unit 101 may calculate |I using the weighting factors w1 and w2 stored in the weighting factor setting unit 102. dqw Calculate |.

[0053]

[0054] 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 calculates |I dqw10 shows the configuration of the beatless control unit 18 when calculating | and outputting it to the pulsation extraction unit 103.

[0055] 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.

[0056] For example, when it is desired to suppress the phase current peak value, the beatless control unit 18 sets |I dq |2 to reduce pulsation. Furthermore, when it is desired to reduce vibration and noise of the AC motor 1, the beatless control unit 18 sets w1 = 0 and w2 = 1 to reduce pulsation in the q-axis current. Furthermore, when an intermediate state between these two is desired, the beatless control unit 18 may change the weighting factors w1 and w2, such as w1 = 0.5 and w2 = 0.5. Furthermore, 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. Furthermore, 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 reduce pulsation in the d-axis current.

[0057] The calculations in the norm calculation unit 101 are performed to set the major and minor axis directions of the elliptical current locus Itb of the dq axis current to the angle desired by the user, and are performed to make beatless control work effectively.

[0058] 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 set arbitrarily by the user of the drive unit 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 set arbitrarily by the user of the drive unit 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.

[0059] The pulsation extraction unit 103 extracts the norm (unweighted norm |I dqw | or weighted norm |I dqw The frequency component extracted by the pulsation extractor 103 at this time is the disturbance frequency f dis and the disturbance frequency f dis The pulsation extracting unit 103 may extract the norm pulsation component by any extraction method.

[0060] 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.

[0061] 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 automatic search unit 104.

[0062] The automatic search unit 104 detects the disturbance frequency f dis Using y sin , y cos The voltage phase control amount θ that minimizes b For example, the manipulated variable θ b If there are no constraints on y sin = 0 and y cos = 0 is y sin and y cos The minimum value of the operation amount θ b If there is a constraint on y sin and y cos The minimum value of the manipulated variable θ b The value is based on the constraints.

[0063] The automatic search unit 104 determines the operation amount θ using any of the automatic search methods. bThe automatic search unit 104 may search for the manipulated variable θ using, for example, integral control. b The automatic search unit 104 also searches for the manipulated variable θ using AI (Artificial Intelligence) or machine learning. b You may explore.

[0064] 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 expression (3).

[0065]

[0066] Here, as shown in the following equation (4), ω dis The integral result of integrating over time t is θ dis We will represent this with the symbol:

[0067]

[0068] where f dis can be considered as a constant, so θ dis can be expressed as a linear function of time t. At this time, the voltage phase control amount θ b can be expressed as, for example, the following equation (5).

[0069]

[0070] In equation (5), x cos , x sin are the cosine and sin components of the output signal of the beatless control. In this beatless control, the automatic search unit 104 calculates y sin , y cos x such that is minimized cos and x sin By using the addition theorem of trigonometric functions, equation (5) can also be written in the form of equation (6) below.

[0071]

[0072] In equation (6), x is θ b and δ is the amplitude of cos(θ dis ) is the phase difference with y sin , y cos Even if the control unit 400 is configured to search for a combination of x and δ that minimizes y sin , y cos x such that is minimized cos and x sin The same effect can be obtained by searching for combinations of

[0073] The reason why the first embodiment aims to minimize the pulsation of the norm or weighted norm is because minimization is the best state that can be achieved in the voltage saturation region of the inverter voltage (inverter overmodulation region). When the DC bus 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.

[0074] In this way, the control unit 400 minimizes the pulsation of an arbitrary norm or weighted norm by appropriately manipulating the phase of the voltage. However, the optimal voltage phase manipulation amount θ in the sense of minimizing the pulsation is b changes in a complex manner depending on the complexity of the control plant in which the AC motor 1 is arranged, the influence of the motor power factor of the AC motor 1, the influence of the power supply inductance 6, etc. Therefore, the control unit 400 of the first embodiment determines the manipulated variable θ of the voltage phase that minimizes the pulsation of an arbitrary norm or weighted norm. b automatically search for

[0075] As a result, the control unit 400 can accurately suppress pulsation in the phase current due to beat vibration with a simple configuration. Note that the effectiveness of beatless control varies depending on the type of norm 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.

[0076] 5 is a flowchart illustrating a procedure of a control process executed by the control unit of the drive 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 (DC bus voltage V DC ) is acquired from the DC bus voltage detection unit 10 (step S20).

[0077] Thereafter, the coordinate conversion unit 17 performs coordinate conversion 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

[0078] 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 dq axis current vector I dq From this, the estimated magnetic pole position θ^, which is the rotor position information, is e and the estimated angular velocity ω^, which is the rotor speed information. e It is estimated that:

[0079] 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 from the dq axis voltage command vector V * dq Calculate the following.

[0080] 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.

[0081] 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^ b 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 Transform the coordinates to

[0082] The modulator 13 performs a modulation calculation (step S80). Specifically, the modulator 13 modulates the DC bus voltage V DC and three-phase voltage command vector V * uvw The modulator 13 determines the PWM signal based on the above.

[0083] Next, a description will be given of the operation of the beatless control unit 18. Fig. 6 is a flowchart showing the procedure of beatless control processing executed by the beatless control unit of the drive device according to the first embodiment.

[0084] 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 d-axis current vector I dq Compute the norm or weighted norm of .

[0085] 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). dis and f dis The pulsation extracting 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 automatic search unit 104.

[0086] The automatic search unit 104 determines the voltage phase manipulation amount θ that minimizes the extracted pulsating component. b Specifically, the automatic search unit 104 automatically searches and calculates the disturbance frequency f dis Using y sin , y cos The voltage phase control amount θ that minimizes b automatically search for

[0087] Next, a description will be given of the hardware configuration of the control unit 400 included in the drive device 4. Fig. 7 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.

[0088] The control unit 400 is realized by a processor 91, a memory 92, and peripheral devices 93. In not only the first embodiment but also the other embodiments, the control unit 400 and control units 400C and 400D described later are realized by the processor 91, the memory 92, and the peripheral devices 93.

[0089] 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. 5.

[0090] 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).

[0091] Examples of the memory 92 include non-volatile or volatile semiconductor memories 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). However, the memory 92 is not limited to these, and may also be a magnetic disk, optical disk, compact disk, minidisc, or DVD (Digital Versatile Disc).

[0092] 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.

[0093] The analog-to-digital conversion circuit is arranged in the modulation unit 13, the coordinate conversion unit 17, etc. The analog-to-digital conversion circuit is used to detect, for example, the DC bus voltage and the phase current of the AC motor 1.

[0094] 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.

[0095] As described above, according to the first embodiment, the control unit 400 of the drive device 4 determines the manipulated variable θ of the voltage phase so as to minimize the extracted pulsating component. b Since the control unit 400 calculates the amplitude of the voltage command, it is possible to reduce the pulsation as intended even in the voltage saturation region of the inverter voltage, where the amplitude of the voltage command cannot be manipulated. This allows the control unit 400 to effectively suppress beat vibrations caused by pulsation of the DC bus voltage, without performing complicated control adjustments.

[0096] 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 unit 4 and improves energy-saving performance.

[0097] 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.

[0098] The control unit 400 also determines the manipulated variable θ of the voltage phase so as to minimize the extracted pulsating component. b Calculate the manipulated variable θ b Since the inverter 11 is controlled using the above, the effect of reducing current pulsation can be easily stabilized regardless of the operating conditions of the drive device 4 or the installation conditions of the drive device 4.

[0099] Second Embodiment Next, a second embodiment will be described with reference to Figs. 8 to 12. In the second embodiment, the target value r *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 is rotated to obtain the voltage phase control amount θ b Automatically search for.

[0100] 8 is a diagram showing the configuration of the automatic search unit included in the beatless control unit according to the second embodiment. The automatic search unit 104 may perform any method of automatic search, but here we will explain the configuration of the automatic search unit 104 when the automatic search unit 104 uses integral control.

[0101] The automatic search 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. * When is set to zero, the automatic search unit 104 searches for a point where the pulsating component becomes zero. * is set to zero, while the target value r * may be a non-zero value.

[0102] The automatic search unit 104 receives a target value r of the pulsating 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 is entered.

[0103] 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. cos The difference between these is calculated, and the calculation result is the cos component deviation e cos to the rotation calculation unit 202.

[0104] 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 sin to the rotation calculation unit 202.

[0105] The rotation calculation unit 202 calculates e cos And, e sin The rotation calculation is performed using the following equation (7). Here, the cos component after the rotation calculation is expressed as e Rcos The sin component after the rotation operation is e Rsin That's what they say.

[0106]

[0107] θ in Equation (7) R is the amount of rotation in the rotation operation. R is set in advance by the user in the rotation amount adjustment unit 205. The rotation amount adjustment unit 205 adjusts the rotation amount θ R is set in the rotation calculation unit 202. The rotation calculation unit 202 may be disposed inside the pulsation extraction unit 103.

[0108] 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 Rsin That is, the integral control unit 203A integrates e Rcos By performing integral control on x cos The integral control unit 203B determines e Rsin By performing integral control on 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

[0109] The integral control unit 203A calculates the rotated cos component e Rcos In other words, the integral control unit 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 The deviation e is the difference betweencos 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 controlling the integral to get closer to x cos Determine.

[0110] Furthermore, the integral control section 203B sets the target value r of the pulsating component * and y, the sin component of the pulsation of the norm or weighted norm sin The deviation e is the difference between 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 controlling the integral to get closer to x sin Determine.

[0111] Although the automatic search unit 104 uses integral control units 203A and 203B in this example, other control units that include an integral element may be used for the automatic search unit 104. For example, the automatic search unit 104 may use a control unit that performs PI (Proportional-Integral) control or a control unit that performs PID (Proportional-Integral-Differential) control.

[0112] 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 Specifically, the AC restoration unit 204 calculates x in equations (3) to (5). cos , x sin , and f dis By applying this, the voltage phase control amount θ b The following equations are used to calculate f dis is applied, so that f dis The sine and cosine waves corresponding to f are derived, disThe corresponding control variable θ b is derived.

[0113] Fig. 9 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the second embodiment executes beatless control when the rotation amount is in an optimal state. 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 when the rotation amount is within a range of less than ±90 degrees from the optimal value. Fig. 11 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the second embodiment executes beatless control when the rotation amount is away from the optimal value by more than ±90 degrees.

[0114] 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 rotation amount θ is more than ±90 degrees away from the optimum value, R and the optimum value is greater than 90 degrees.

[0115] The horizontal axis in Figures 9 to 11 is the cos component (e cos ), and the vertical axis is the sin component (e sin 9 to 11 show the results of the beatless control performed by the beatless control unit 18. cos and e sin The deviation vector E is a motion pattern of the deviation vector E (not shown) that is composed of the deviation vector E from the origin (e cos , e sin ) is a vector pointing to the beatless control unit 18. cos , e sin ) approaches the origin, i.e., the absolute value of the deviation vector E decreases. 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 RThey can be roughly classified into four types depending on the

[0116] The first operation pattern shown in FIG. R When the beatless control unit 18 starts beatless control in this state, e cos and 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.

[0117] The second operation pattern shown in FIG. 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.

[0118] The third operation pattern shown in FIG. 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.

[0119] 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.

[0120] The rotation amount adjustment unit 205 is supplied with a rotation amount θ that is as close to the optimum value as possible by the user in advance. R The rotation amount adjustment unit 205 is set to, for example, a rotation amount θ of less than ±85 degrees from the optimum value. R is set.

[0121] The beatless control unit 18 according to the second embodiment has the automatic search unit 104 shown in FIG. 8, and therefore the rotation amount adjustment unit 205 adjusts the rotation amount θ R If is given appropriately, the deviation e cos , e sin It is possible to control the pulsating component to zero. * is set to zero, so the deviation e cos , esin 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.

[0122] The amount of rotation θ R is not limited to being set in advance by the user, but may be adjusted while the AC motor 1 is operating. In this case, the dq-axis current vector I dq , the rotation amount θ based on the rotation speed of the AC motor 1, etc. R is adjusted. Also, the rotation amount θ R may be determined by some additional information provided from outside the drive device 4. The rotation amount adjustment unit 205 adjusts the rotation amount θ R Remember the following.

[0123] Next, the operation of the automatic search unit 104 will be described. Fig. 12 is a flowchart showing the procedure of automatic search processing executed by the automatic search unit of the drive device according to embodiment 2. The automatic search unit 104 automatically searches for a point at which the pulsation of the norm or weighted norm is minimum, in the following procedure.

[0124] 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 is set in the rotation calculation unit 202 (step S220).

[0125] 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 the above to equation (7), the cosine component after the rotation operation, e Rcos and the sin component after the rotation operation, e Rsin Calculate and.

[0126] The integral control units 203A and 203B execute integral control calculations (step S240). Specifically, the integral control unit 203A calculates eRcos 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 sin component of the output signal of beatless control, sin Determine.

[0127] The AC restoration unit 204 performs AC restoration calculation (step S250). Specifically, the AC restoration unit 204 adds x to the equations (3) to (5). cos , x sin , and f dis By applying this, the voltage phase control amount θ b Calculate the following.

[0128] Thus, according to the second embodiment, the control unit 400 of the drive unit 4 controls the rotation amount θ R is in an appropriate state (rotation amount θ R is within a range of less than ±90 degrees from the optimum value), beat vibration caused by pulsation of the DC bus voltage can be effectively suppressed without performing complicated control adjustments.

[0129] Third Embodiment Next, a third embodiment will be described with reference to Figs. 13 to 21. In the method described in the second embodiment, the amount of rotation θ R is in a certain appropriate state, beat vibration caused by pulsation of the DC bus voltage can be effectively suppressed. R If the status is inappropriate, correct it to the appropriate status.

[0130] Fig. 13 is a diagram showing the configuration of a beatless control unit provided in a drive device according to embodiment 3. Of the components in Fig. 13, those that achieve the same functions as those of the beatless control unit 18 of embodiment 1 shown in Fig. 4 are given the same reference numerals, and redundant explanations will be omitted.

[0131] Compared to the drive device 4 of embodiment 1, the drive device 4 of embodiment 3 has a beatless control unit 18A instead of the beatless control unit 18. The beatless control unit 18A has a search failure detection unit 105 in addition to the components of the beatless control unit 18. Also, compared to the beatless control unit 18, the beatless control unit 18A has an automatic search unit 104A instead of the automatic search unit 104.

[0132] The search failure detection unit 105 detects y 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 outputs a search direction correction signal, which is a signal for correcting the search direction, to the automatic search unit 104A. R By adjusting the manipulated variable θ b The search direction (the direction of the deviation vector E) is a signal for correcting the search direction of the deviation vector E. The search direction is the operation amount θ b In other words, the search direction corresponds to the cos component (x cos ) and sin component (x sin ) to the optimum value cos and x sin The search failure detection unit 105 detects y cos and y sin When it detects that both of the values ​​have increased, it outputs a search direction correction signal to the automatic search section 104A.

[0133] Upon receiving the search direction correction signal, the automatic search unit 104A corrects the search direction. cos and y sin By finding a search direction that reduces the deviation vector E, the deviation vector E is eventually driven to zero.

[0134] FIG. 14 is a diagram showing an operation pattern of a deviation vector when the beatless control unit according to the third embodiment executes beatless control. The horizontal axis of FIG. 14 represents the cosine component (e cos ), and the vertical axis is the sin component (esin 14, when the beatless control unit 18A executes beatless control, e cos and e sin 10 shows a deviation vector locus Et, which is a motion pattern of the deviation vector E. The deviation vector locus Et has a starting point "Start" and an end point "Goal".

[0135] When beatless control is performed, y is the cosine component of the pulsation of the norm or weighted norm of the dq axis current. cos , and the sin component y sin The voltage phase control amount θ that minimizes b If the automatic search is not performed properly, cos and y sin The beatless control unit 18A of the third embodiment increases such y cos and y sin Detect an increase in

[0136] In the beatless control unit 18A, the search failure detection unit 105 cos and y sin When an unintended increase in is detected, it is determined that the beatless control is in an abnormal state and a search direction correction signal is output.

[0137] When the automatic search unit 104A receives the search direction correction signal, it corrects the search direction. The search failure detection unit 105 continues to output the search direction correction signal while it determines that the beatless control is in an abnormal state. Furthermore, when the search failure detection unit 105 determines that the beatless control is in a normal state, it stops outputting the search direction correction signal. The automatic search unit 104A continues to correct the search direction until it no longer receives the search direction correction signal. This correction operation causes y cos and y sin decreases, and the deviation vector E becomes zero. This allows the driving device 4 to reliably suppress beat vibration under any operating conditions.

[0138] The concept of the search direction corrected by the beatless control unit 18A will now be described. Fig. 15 is a first explanatory diagram illustrating the search direction corrected by the beatless control unit according to the third embodiment. Fig. 16 is a second explanatory diagram illustrating the search direction corrected by the beatless control unit according to the third embodiment. Fig. 17 is a third explanatory diagram illustrating the search direction corrected by the beatless control unit according to the third embodiment. Fig. 18 is a fourth explanatory diagram illustrating the search direction corrected by the beatless control unit according to the third embodiment.

[0139] 15 to 18 show an image of the search direction corrected by the beatless control unit 18A. The horizontal axis of each of the figures shows the cosine component (e cos , e Rcos , x cos ), and the vertical axis is the sin component (e sin , e Rsin , x sin 15 to 17, compared to FIGS. 9 to 11, 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 region 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.

[0140] 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).

[0141] 15 to 18, the search direction is represented by a sector-shaped figure (sector region) that mimics the human field of vision. If the center of the sector region is the position of the output signal vector x at a certain time, the arc of the sector region represents the forward field of vision at that time.

[0142] Specifically, in Fig. 15, the image of the search direction is shown by search direction image SD1, and in Fig. 16, the image of the search direction is shown by search direction images SD2 and SD3. In Fig. 17, the image of the search direction is shown by search direction images SD4, SD5, and SD6, and in Fig. 18, the image of the search direction is shown by search direction images SD7 and SD8.

[0143] The search direction image SD1 shown in FIG. 15 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.

[0144] The search direction images SD2 and SD3 shown in FIG. 16 are rotated by a rotation amount 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 elapsed since the start of the search using search direction image SD2.

[0145] The search direction images SD4, SD5, and SD6 shown in FIG. 17 are rotated by a rotation amount θ R 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 a search direction image after a specific time has elapsed since the start of the search using search direction image SD4. Search direction image SD6 is a search direction image after a specific time has elapsed since the search using search direction image SD5.

[0146] 15 to 17, the trajectory of the deviation vector E before the rotation calculation as it moves from the point of the initial value Es of the deviation vector E to the point of the ideal value Ei of the deviation vector E (the origin) is shown as the deviation vector trajectory Et.

[0147] 15 to 17, the trajectory of the deviation vector ER after the rotation calculation as it moves 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 (the origin) is shown as a deviation vector trajectory ERt.

[0148] In addition, in FIG. 18, 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 as it moves 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 ERt2.

[0149] Here, it is assumed that if the ideal value of the output signal vector x can be found, 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 18A cannot know in advance where the ideal value of the output signal vector x is located in the diagram.

[0150] The beatless control unit 18A 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 18A searches for an output signal vector x that minimizes the deviation vectors E and ER within the searchable range SR.

[0151] 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. 15 to 17, 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. The initial value ERs of the deviation vector ER may be the same as the initial value Es of the deviation vector E.

[0152] In FIG. 15, a beatless control unit 18A according to the third embodiment controls the rotation amount θ R 10 shows the operation patterns of the deviation vectors E and ER and the output signal vector x when beatless control is performed when the

[0153] 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 are 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.

[0154] 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, the output signal vector x cannot 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 18A calculates the rotation amount θ R If the above equation is set to an optimum state, the deviation vectors E and ER can be moved toward the ideal value Ei in the shortest distance.

[0155] Since the output signal vector x moves in the direction of the deviation vector ER as viewed from the origin, the direction of the deviation vector ER as viewed 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.

[0156] The sector area (search direction image SD1) shown in FIG. 15 is rotated by a rotation amount θ R is the optimum value. In this case, the ideal value x of the output signal vector x is on the extension of the search direction, so the search for the ideal value x of the output signal vector x is successful.

[0157] The sector area (search direction images SD2 and SD3) shown in FIG. 16 is rotated by a rotation amount 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 18A'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 18A can cause the deviation vectors E and ER to ultimately 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.

[0158] The sector areas (search direction images SD4, SD5, SD6) shown in FIG. 17 are rotated by a rotation amount θ R 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 output signal vector x is changed, the deviation vectors E and ER do not decrease as intended, so the beatless control unit 18A cannot uniquely determine the search direction and manipulates the output signal vector x so that the deviation vectors E and ER are directed toward a point different from the ideal value Ei. As a result, the beatless control unit 18A increases the deviation vectors E and ER along a trajectory that resembles a spiral, resulting in beatless control failure.

[0159] 17, 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. 17, the point of the output signal vector x when a search failure is detected is indicated by the reached value xf.

[0160] In the third embodiment, in preparation for the case where the deviation vectors E and ER perform the operation shown in FIG. 17, the beatless control unit 18A is configured to control the rotation amount θ R The search failure detection unit 105 detects a failure in the search for the optimal value of . The cause of the failure in the search in the operation described in FIG. 17 is that the search direction is inappropriate (in other words, the rotation amount θ R If the search fails, the beatless control unit 18A detects the failure of the search and corrects the search direction, thereby eventually adjusting the rotation amount θ R can be successfully searched for the optimal value of

[0161] In FIG. 18, the rotation amount θ R 18 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. 18 shows the operation image in the case where, when the beatless control unit 18A detects a search failure, the beatless control unit 18A corrects the search direction and performs the search again. R Adjust the rotation amount θ R 17, the points of the deviation vectors E and ER when a search failure is detected are indicated by deviation vectors Ef and ERf, respectively.

[0162] In FIG. 18, the rotation amount before correction is the rotation amount Bθ R and the corrected rotation amount is represented by the rotation amount Aθ R In addition, in FIG. 18, the beatless control unit 18A changes the rotation amount Bθ R The search direction image after adjusting the rotation amount Bθ is shown as a search direction image SD8. R When the rotation amount is adjusted, the rotation amount Aθ R As a result, the deviation vector ER after the rotation calculation and the search direction change.

[0163] In FIG. 18, the rotation amount Bθ R The locus of the output signal vector x after the adjustment is shown as a locus xt2. R The trajectory of the deviation vector ER rotated by the rotation calculation is shown as a deviation vector trajectory ERt2. R The locus of the deviation vector E rotated by the above calculation is shown as a deviation vector locus Et2.

[0164] Suppose the rotation amount Bθ R By adjusting the rotation amount Aθ R When becomes the optimum value, the ideal value xi of the output signal vector x is on the extension line of the search direction, so the search for the optimum value is completed smoothly.

[0165] For convenience of explanation, in FIG. 18, 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.

[0166] Furthermore, the beatless control unit 18A 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 along a complex deviation vector locus Et as shown in FIG. 14. Also, the deviation vector E may approach the origin along a complex deviation vector locus Et as shown in FIG. 18. R After the correction, the deviation vector E may move toward the origin along a linear deviation vector locus Et2.

[0167] In beatless control, it is unclear 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 third embodiment, the beatless control unit 18A appropriately corrects the search direction of the beatless control so that the output signal vector x can reliably reach the ideal value xi.

[0168] Fig. 19 is a diagram showing the configuration of an automatic search unit included in the beatless control unit according to the third embodiment. Of the components in Fig. 19, those that achieve the same functions as the automatic search unit 104 of the first embodiment shown in Fig. 8 are assigned the same reference numerals, and redundant explanations will be omitted.

[0169] The automatic search unit 104A of the third embodiment differs from the automatic search unit 104 of the second embodiment in that it has a rotation amount adjustment unit 206 instead of the rotation amount adjustment unit 205. The rotation amount adjustment unit 206 receives a search direction correction signal from the search failure detection unit 105. Upon receiving the search direction correction signal, the rotation amount adjustment unit 206 adjusts the rotation amount θ R The rotation amount adjustment unit 206 adjusts the adjusted rotation amount θ R is output to the rotation calculation unit 202.

[0170] 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 adjusts the rotation amount θ R may be automatically searched for.

[0171] The rotation calculation unit 202 receives the rotation amount θ from the rotation amount adjustment unit 206. R The rotation calculation unit 202 receives the rotation amount θ received from the rotation amount adjustment unit 206. R Using e cos and sin A rotation operation is performed on and .

[0172] Here, the rotation amount θ RAn example of a method for adjusting the voltage phase will be described. Fig. 20 is a diagram showing a first behavior of the deviation vector when the beatless control unit according to the third embodiment automatically searches for the manipulated variable for the voltage phase. Fig. 21 is a diagram showing a second behavior of the deviation vector when the beatless control unit according to the third embodiment automatically searches for the manipulated variable for the voltage phase. Fig. 22 is a diagram showing a third behavior of the deviation vector when the beatless control unit according to the third embodiment automatically searches for the manipulated variable for the voltage phase.

[0173] The horizontal axis in Figures 20 to 22 is the cos component (e cos ), and the vertical axis is the sin component (e sin 20 to 22, the automatic search unit 104A calculates the voltage phase manipulated variable θ b When automatically searching for cos and e sin 10A and 10B show the behavior of a deviation vector E.

[0174] The automatic search unit 104A calculates the voltage phase manipulated variable θ b Whether the automatic search for is being performed properly can be determined by checking 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.

[0175] The automatic search unit 104A determines that the automatic search is being performed satisfactorily 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. 20. Furthermore, when the direction of the time differential vector (d / dt)E is inward (toward the origin) from the perpendicular line of the deviation vector E, as in the second behavior of the deviation vector E shown in Fig. 21, the automatic search unit 104A determines that the automatic search is being performed appropriately to a certain extent.

[0176] When the direction of the time differential vector (d / dt)E is outward from the perpendicular line of the deviation vector E, as in the third behavior of the deviation vector E shown in Figure 22, the automatic search unit 104A determines that the automatic search is not being performed appropriately.

[0177] If the state of the deviation vector E shown in FIG. 22 is left as it is, the beatless control will become unstable and diverge. Therefore, the automatic search unit 104A adjusts the rotation amount θ so that the deviation vector E is in the state shown in FIG. 20 or 21. R Fix.

[0178] As shown in FIG. 21, when the direction of the time differential vector (d / dt) E is inward from the perpendicular line of the deviation vector E, the automatic search unit 104A adjusts the rotation amount θ so that the direction of the time differential vector (d / dt) E is further inward. R may be corrected.

[0179] The automatic search unit 104A calculates the rotation amount θ R In order to correct the rotation amount θ , the automatic search unit 104A evaluates whether the beatless control is being performed appropriately using a quantitative numerical value (evaluation value). R Fix.

[0180] 23 is a diagram illustrating an evaluation value used by the automatic search unit according to the third embodiment to evaluate whether beatless control is being performed appropriately. The horizontal axis of FIG. 23 represents the cosine component, and the vertical axis represents the sinusoidal component.

[0181] 23 shows an example of the definition of the evaluation value. The automatic search unit 104A evaluates the appropriateness of the beatless control operation 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 differential vector (d / dt)E of the deviation vector E is C d is.

[0182] The automatic search unit 104A determines that the smaller the area of ​​the parallelogram formed by the deviation vector E and the time differential vector (d / dt) E of the deviation vector E, the greater the rotation amount θ R As 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 correction amount of the rotation amount θ RThat is, the automatic search unit 104A adjusts the rotation amount θ as the angle between the deviation vector E and the time differential vector (d / dt)E approaches 90 degrees. R Increase the correction amount.

[0183] 24 is a diagram showing the configuration of a rotation amount adjustment unit included in the automatic search unit according to embodiment 3. The rotation amount adjustment unit 206 according to embodiment 3 includes a cross product calculation unit 300, a dead zone 305, and a PID control unit 306.

[0184] 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 deviation e cos is input, and the deviation e is output from the subtractor 201B. sin is entered.

[0185] The symbol s shown in Fig. 24 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. 24 describes a case where the pseudo differentiators 302A and 302B are provided with a low-pass filter for removing differentiation noise.

[0186] 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 the pseudo differentiator 302B and the multiplier 303A.

[0187] 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 the result to the multiplier 303A. sin and (d / dt)e cos and outputs the multiplication result to the subtractor 304.

[0188] The pseudo differentiator 302B calculates the deviation e sinBy 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.

[0189] 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.

[0190] 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 third embodiment adjusts the rotation amount θ by the dead zone 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.

[0191] 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 rotation calculation unit 202. Note that the rotation amount θ R The adjustment of the rotation amount θ may be performed using any circuit. R The 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, another type of control unit or AI may be used to adjust the rotation amount θ R may be adjusted.

[0192] The rotation amount adjustment unit 206 adjusts the rotation amount θ R When the value of the beatless control is changed, 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 RAt this time, the change in the rotation amount θ R Since is an appropriate value, the deviation vector E will eventually converge to zero.

[0193] Next, a description will be given of the operation of the rotation amount adjustment unit 206. Fig. 25 is a flowchart showing the procedure of the rotation amount adjustment process executed by the rotation amount adjustment unit according to the third embodiment.

[0194] The cross product calculation unit 300 calculates C, which is an evaluation value for determining whether beatless control is being performed appropriately. d In other words, the cross product calculation unit 300 calculates the deviation e of the cosine component calculated by the subtractor 201A by the cross product calculation (step S320). cos and the deviation e calculated by the subtractor 201B. sin Based on this, the evaluation value C d Calculate the following.

[0195] 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 is zero R Adjust.

[0196] As described above, according to the third 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, beat vibration caused by pulsation of the DC bus voltage can be effectively suppressed under any operating conditions without performing complicated control adjustments.

[0197] Fourth Embodiment Next, a fourth embodiment will be described with reference to Fig. 26. In the fourth embodiment, the beatless control is parallelized to reduce the disturbance frequency f dis (fundamental frequency) and harmonic components are simultaneously suppressed.

[0198] Fig. 26 is a diagram showing the configuration of a beatless control unit provided in a drive device according to embodiment 4. Of the components in Fig. 26, those that achieve the same functions as those of the beatless control unit 18 of embodiment 1 shown in Fig. 4 are given the same reference numerals, and redundant explanations will be omitted.

[0199] Compared to the drive device 4 of embodiment 1, the drive device 4 of embodiment 4 has a beatless control unit 18B instead of the beatless control unit 18. Compared to the beatless control unit 18, the beatless control unit 18B has a pulsation extraction unit 103B instead of the pulsation extraction unit 103, and an automatic search unit 104B instead of the automatic search unit 104.

[0200] In the beatless control unit 18B, a pulsation extraction unit 103B and an automatic search unit 104B detect a disturbance frequency f dis The control system (suppression system) for the disturbance frequency f and the control system for the harmonic components are arranged in parallel. dis The drive unit 4 of the fourth embodiment has a pulsation extraction unit 103B and an automatic search unit 104B in which the control systems for the harmonic components are parallelized. Generally, the pulsation (pulsation component) of the DC bus voltage contains harmonic components, so the dq-axis currents of the AC motor 1 are affected by the harmonic components. For this reason, in order to reduce the pulsation of the norm or weighted norm of the dq-axis currents, the drive unit 4 of the fourth embodiment has a disturbance frequency f dis and suppresses harmonic components simultaneously.

[0201] For example, the disturbance frequency f dis and the disturbance frequency f dis N times (N is an integer of 2 or more) the disturbance frequency Nf dis When it is desired to simultaneously suppress both the disturbance frequency f dis and disturbance frequency Nf dis In this case, the voltage phase control amount θ b is defined as the following equation (8).

[0202]

[0203] x in equation (8) cosN , x sinNare the cos Nf component and sin Nf component, respectively, of the output signal of beatless control. The pulsation extraction unit 103B extracts the sin 1F component, cos 1F component, sin Nf component, and cos Nf component, which are pulsation components, from the norm or weighted norm calculated by the norm calculation unit 101, for example. Here, the extracted pulsation components are represented by the symbols ysin, ycos, ysinN, and ycosN, respectively.

[0204] The pulsation extraction unit 103B extracts ysin and ycos, which are fundamental frequency components, and ysinN and ycosN, which are harmonic components, as the pulsation components of the norm. The automatic search unit 104B finds x such that ysin, ycos, ysinN, and ycosN are simultaneously minimized. cos , x sin , x cosN , x sinN In other words, the automatic search unit 104B searches for a manipulation variable that simultaneously minimizes the fundamental frequency and harmonic components. The automatic search unit 104B may use any search method to search for a combination. The automatic search unit 104B performs the search using, for example, the search methods described in the first to third embodiments.

[0205] In the fourth embodiment, the control systems for the fundamental wave and harmonics are described in parallel, but if it is desired to simultaneously suppress harmonic components of multiple orders, parallelization can be performed for the beatless control unit 18B in a manner similar to that described in Figure 26.

[0206] For example, the disturbance frequency f dis and the disturbance frequency Nf dis and the disturbance frequency f dis M times (M is an integer greater than or equal to 2 and different from N) of the disturbance frequency Mf dis When it is desired to simultaneously suppress the disturbance frequency f dis and disturbance frequency Nf dis and disturbance frequency Mf disare input. The pulsation extraction unit 103B extracts, for example, a sin 1F component, a cos 1F component, a sin Nf component, a cos Nf component, a sin Mf component, and a cos Mf component, which are pulsation components, from the norm or weighted norm calculated by the norm calculation unit 101. The automatic search unit 104B searches for a combination of the cos 1f component, the sin 1f component, the cos Nf component, the sin Nf component, the cos Mf component, and the sin M component of the beatless control output signal, such that each of the extracted pulsation components is minimized.

[0207] As described above, according to the fourth embodiment, the control unit 400 of the drive unit 4 performs beatless control in parallel, and therefore, even when the pulsation of the DC bus voltage contains large harmonic components, beat vibration can be effectively suppressed without performing complicated control adjustments.

[0208] Fifth Embodiment Next, a fifth embodiment will be described with reference to Figs. 27 to 29. In the fifth embodiment, the disturbance frequency f dis When the LC (electro-conductive) resonance frequency of the DC reactor 8 and the capacitor 9 approaches, the manipulated variable θ of the voltage phase b The range of search is limited.

[0209] Fig. 27 is a diagram showing the configuration of a drive device according to embodiment 5. Of the components in Fig. 27, those that achieve the same functions as those in drive device 4 of embodiment 1 shown in Fig. 1 are given the same reference numerals, and duplicated explanations will be omitted.

[0210] Compared to the drive device 4 of the first embodiment, the drive device 4C of the fifth embodiment has a control unit 400C instead of the control unit 400. Compared to the control unit 400, the control unit 400C has a beatless control unit 18C instead of the beatless control unit 18.

[0211] In the drive device 4C, the DC bus voltage detection unit 10 is connected to the beatless control unit 18C and the modulation unit 13. The beatless control unit 18C receives the DC bus voltage V DC Accept.

[0212] A source impedance exists between the drive unit 4C and the AC power supply 5. The source inductance 6, which is the inductance component of the source impedance, is an unknown parameter that varies depending on the installation environment of the drive unit 4C, the power supply environment, the operating conditions of surrounding electrical devices (hereinafter referred to as peripheral electrical devices), etc. If the source inductance 6, DC reactor 8, and capacitor 9 resonate with each other, large pulsations may occur in the DC bus voltage.

[0213] The disturbance frequency f targeted by beatless control dis When the LC resonant frequencies of the DC reactor 8 and the capacitor 9 are close to each other, minimizing the pulsation of the d-axis current norm or weighted norm can significantly increase the pulsation amplitude of the DC bus voltage. In such a case, if beatless control is too effective, the d-axis current waveforms can become distorted. This phenomenon is likely to become a problem when the power supply impedance is larger than the impedance on the drive unit 4C side.

[0214] In the fifth embodiment, the driving device 4C has a disturbance frequency f dis When the drive unit 4C detects that the LC resonance frequency of the DC reactor 8 and the capacitor 9 approaches the normal pulsation, the drive unit 4C detects that the pulsation of the DC bus voltage has increased. b In this way, the driving device 4C obtains a good current waveform by suppressing the beatless control operation.

[0215] Fig. 28 is a diagram showing the configuration of a beatless control unit provided in a drive device according to embodiment 5. Of the components in Fig. 28, those that achieve the same functions as those of the beatless control unit 18 of embodiment 1 shown in Fig. 4 are given the same reference numerals, and redundant explanations will be omitted.

[0216] The beatless control unit 18C of the fifth embodiment has a search range limiting unit 106 in addition to the components of the beatless control unit 18 of the first embodiment. Also, compared to the beatless control unit 18 of the first embodiment, the beatless control unit 18C has an automatic search unit 104C instead of the automatic search unit 104.

[0217] The search range limiting unit 106 calculates the DC bus voltage V DC is received from the DC bus voltage detection unit 10. The search range limiting unit 106 receives the DC bus voltage V DC Based on this, the manipulated variable θ b The search range is calculated and output to the automatic search unit 104C.

[0218] When the pulsation amplitude of the DC bus voltage increases excessively, specifically when the pulsation amplitude of the periodic pulsation of the DC bus voltage exceeds a specific threshold, the search range limiting unit 106 determines that LC resonance and beatless control are interfering with each other, and limits the search range to a specific range. LC resonance is inductor-capacitor resonance between the inverter 11 and the AC power source 5 that supplies power to the inverter 11. The automatic search unit 104C finds a point (a manipulated variable θ of the voltage phase) at which the norm or weighted norm of the d-axis current or the q-axis current is minimum within the search range specified by the search range limiting unit 106. b ) is automatically searched for. This allows the beatless control unit 18C to suppress beat vibration while avoiding the influence of LC resonance.

[0219] Fig. 29 is a diagram showing the configuration of an automatic search unit provided in the beatless control unit according to the fifth embodiment. Of the components in Fig. 29, those that achieve the same functions as those of the beatless control unit 18 of the first embodiment shown in Fig. 8 are given the same reference numerals, and redundant explanations will be omitted.

[0220] The automatic searching unit 104C of the fifth embodiment has a limit value adjusting unit 207 in addition to the components of the automatic searching unit 104 of the first embodiment. Furthermore, compared to the automatic searching unit 104 of the first embodiment, the automatic searching unit 104C has integral control units 203C and 203D instead of integral control units 203A and 203B.

[0221] The limit value adjustment unit 207 calculates limit values ​​to be set in the integral control units 203C and 203D based on the search range sent from the search range restriction unit 106. That is, the limit value adjustment unit 207 converts the search range information into limit values ​​for the integral control units 203C and 203D. The limit value adjustment unit 207 outputs the calculated limit values ​​to the integral control units 203C and 203D. As a result, the limit values ​​applied by the integral control units 203C and 203D are adjusted.

[0222] In the case of a search method using integral control, the automatic search unit 104C can limit the search range by adjusting the limit values ​​of integrators such as integral control units 203C and 203D. The integral control units 203C and 203D operate according to the limit values ​​received from limit value adjustment unit 207. The integral control units 203C and 203D perform the same processing as integral control units 203A and 203B within the range of the limit values.

[0223] As described above, according to the fifth embodiment, the control unit 400 of the drive unit 4 controls the disturbance frequency f dis In a situation where the LC resonance frequency is close to the LC resonance frequency, the operation of the beatless control is limited so that the beatless control is not made too effective. This allows the control unit 400 to prevent an excessive increase in the pulsation of the DC bus voltage or a deterioration in the dq-axis current pulsation due to the increase in pulsation, without performing complicated control adjustments.

[0224] Sixth Embodiment Next, a sixth embodiment will be described with reference to Figures 30 and 31. In the sixth embodiment, a drive unit (a drive unit 4D described later) uses additional information to improve the search speed of an automatic search.

[0225] The driving devices 4 and 4C described in the first to fifth embodiments are designed to achieve a target frequency for beatless control (disturbance frequency f dis When the LC resonant frequency is sufficiently far from the LC resonant frequency, the pulsation of an arbitrary norm or weighted norm can be minimized by appropriately manipulating the voltage phase. In these driving devices 4 and 4C, the optimum voltage phase manipulation amount θ bHowever, since this varies in a complex manner depending on the complexity of the control plant in which the AC motor 1 is placed, the influence of the motor power factor of the AC motor 1, the influence of the power supply inductance 6, etc., the time required for automatic search may be long depending on the operating conditions.

[0226] In the sixth embodiment, a priority search direction (priority search direction) is set using additional information including at least one of the characteristics of the control plant in which the AC motor 1 is placed, the motor power factor of the AC motor 1, the estimated value of the power supply inductance 6, and the status (installation status, connection status, operation status) of peripheral electrical equipment placed around the AC motor 1.

[0227] The peripheral electric device is, for example, a device (such as another drive device) connected in parallel to the AC power supply 5 together with the drive device 4D. In this case, the peripheral electric device and the drive device 4D are connected in parallel to the AC power supply 5. The power supply inductance 6 differs between when the peripheral electric device is connected to the AC power supply 5 and when the peripheral electric device is not connected to the AC power supply 5. For this reason, in the sixth embodiment, information about the status of the peripheral electric device may be included in the additional information.

[0228] The additional information may be any information other than the above-described information as long as it is useful for beatless control. The additional information may be sent to the drive unit 4D from a calculation device (not shown) disposed outside the drive unit 4D, or may be calculated within the drive unit 4D.

[0229] Fig. 30 is a diagram showing the configuration of a drive device according to embodiment 6. Of the components in Fig. 30, those that achieve the same functions as those in drive device 4 according to embodiment 1 shown in Fig. 1 are given the same reference numerals, and duplicated explanations will be omitted.

[0230] Compared to the drive device 4 of the first embodiment, the drive device 4D of the sixth embodiment has a control unit 400D instead of the control unit 400. Compared to the control unit 400, the control unit 400D has a beatless control unit 18D instead of the beatless control unit 18.

[0231] The beatless control unit 18D receives additional information from the outside. The additional information may be sent to the drive unit 4D from a calculation device (not shown) located outside the drive unit 4D, or may be calculated within the drive unit 4D. The beatless control unit 18D determines a priority search direction based on the additional information.

[0232] Fig. 31 is a diagram showing the configuration of a beatless control unit provided in a drive device according to embodiment 6. Of the components in Fig. 31, those that achieve the same functions as those of the beatless control unit 18 of embodiment 1 shown in Fig. 4 are given the same reference numerals, and redundant explanations will be omitted.

[0233] The beatless control unit 18D of the sixth embodiment includes a priority search direction instruction unit 107 in addition to the components included in the beatless control unit 18 of the first embodiment. Furthermore, compared to the beatless control unit 18 of the first embodiment, the beatless control unit 18D includes an automatic search unit 104D instead of the automatic search unit 104.

[0234] The priority search direction instruction unit 107 determines the priority search direction based on the additional information and instructs the determined priority search direction to the automatic search unit 104D. In the case of the automatic search method using integral control described in the second to fifth embodiments, the beatless control unit 18D determines the rotation amount θ R By changing the additional information, the beatless control unit 18D can change the priority search direction. This allows the beatless control unit 18D to suppress current pulsation in a short time by specifying the priority search direction based on the additional information.

[0235] As described above, according to the sixth embodiment, the control unit 400 of the drive unit 4 indicates the priority search direction based on the additional information, and therefore, beat vibrations caused by pulsations in the DC bus voltage can be effectively suppressed in a short time without performing complicated control adjustments.

[0236] Seventh Embodiment Next, a seventh embodiment will be described using Figure 32. In the seventh embodiment, the drive units 4, 4C, and 4D described in the first to sixth embodiments are applied to a refrigeration cycle apparatus. While any of the drive units 4, 4C, and 4D may be applied to the refrigeration cycle apparatus, the following description will be given of the case where the drive unit 4 is applied to the refrigeration cycle apparatus as an example.

[0237] Fig. 32 is a diagram showing the configuration of a refrigeration cycle apparatus according to embodiment 7. Among the components in Fig. 32, components that achieve the same functions as the drive device 4 and the compressor 3 of embodiment 1 shown in Fig. 1 are assigned the same reference numerals, and duplicated explanations will be omitted.

[0238] The refrigeration cycle apparatus 900 of the seventh 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.

[0239] The 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 the compressor drive system 800, a compressor 3, a drive unit 4, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910 are connected via refrigerant piping 912.

[0240] The compressor 3 contains 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.

[0241] During heating operation, as shown by the solid arrow, 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.

[0242] During cooling operation, as shown 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.

[0243] 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 reduces the pressure of the refrigerant to expand it.

[0244] Thus, according to the seventh 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 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, an increase in vibration and noise of the AC motor 1, and the like.

[0245] 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, thereby reducing the manufacturing cost of the refrigeration cycle apparatus 900 and improving the energy-saving performance.

[0246] 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.

[0247] REFERENCE SIGNS LIST 1 AC motor, 2 Mechanical device, 3 Compressor, 4, 4C, 4D 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, 18A to 18D Beatless control unit, 19 Adder, 91 Processor, 92 Memory, 93 Peripheral equipment, 101 Norm calculation unit, 102 Weighting coefficient setting unit, 103, 103B Pulsation extraction unit, 104, 104A to 104D Automatic search unit, 105 Search failure detection unit, 106 Search range restriction unit, 107 Priority search direction instruction unit, 201A, 201B, 304 Subtractor, 202 rotation calculation unit, 203A to 203D integral control unit, 204 AC restoration unit, 205, 206 rotation amount adjustment unit, 207 limit value adjustment unit, 300 cross product calculation unit, 302A, 302B pseudo differentiator, 303A, 303B multiplier, 305 dead band, 306 PID control unit, 400, 400C, 400D 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.

Claims

1. A drive device that drives an AC motor using an inverter, comprising: a current detection unit that detects a current flowing in the AC motor; a rotor position calculation unit that calculates rotor position information that is information about the position of a rotor of the AC motor; 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, wherein the beatless control unit has: a norm calculation unit that calculates the norm of the current vector; a pulsation extraction unit that extracts a pulsation component of the norm; and an automatic search unit that searches for a manipulation variable for the voltage phase that minimizes the pulsation component, and the beatless control unit manipulates the voltage phase using the manipulation variable.

2. The drive device according to claim 1, characterized in that the pulsation extraction unit separates and extracts the pulsation component of the norm into a cosine component and a sine component, and the automatic search unit searches for the manipulated variable that minimizes the cosine component and the sine component.

3. The drive device according to claim 2, characterized in that the automatic search unit comprises: a rotation calculation unit that performs a rotation calculation on the cosine component and the sine component; a first integral control unit that integrates the rotated cosine component; a second integral control unit that integrates the rotated sine component; and an AC restoration unit that calculates the manipulated variable based on the integrated cosine component, the integrated sine component, and a disturbance frequency that is the pulsation frequency of the DC bus voltage.

4. The drive device described in claim 3, characterized in that the beatless control unit further has a search failure detection unit that, when it detects an increase in the cosine component and the sine component, outputs a search direction correction signal to the automatic search unit, which is a signal that corrects the search direction of the manipulated variable by adjusting the rotation amount of the rotation calculation, and the automatic search unit further has a rotation amount adjustment unit that, when it receives the search direction correction signal, adjusts the rotation amount of the rotation calculation, and the rotation calculation unit performs the rotation calculation using the adjusted rotation amount.

5. A drive device as described in any one of claims 1 to 4, characterized in that the pulsation extraction unit extracts a fundamental frequency component and a harmonic component as the pulsation component of the norm, and the automatic search unit searches for the manipulated variable that simultaneously minimizes the fundamental frequency and the harmonic component.

6. A drive device described in any one of claims 1 to 5, characterized in that the beatless control unit further has a search range limiting unit that limits the search range of the manipulated variable to a specific range when the pulsation amplitude of the periodic pulsation exceeds a threshold value.

7. A drive device as described in any one of claims 1 to 6, characterized in that the beatless control unit further has a priority search direction indication unit that determines a priority search direction, which is a direction in which to prioritize searching for the manipulated variable, using additional information including at least one of the following information: characteristics of a control plant in which the AC motor is located; a motor power factor of the AC motor; a power source inductance, which is an inductance component of the power source impedance between the AC power source that supplies power to the inverter; and the status of electrical equipment arranged around the AC motor.

8. The drive device according to any one of claims 1 to 7, characterized in that the automatic search unit searches for the manipulated variable using artificial intelligence or machine learning.

9. The drive device according to any one of claims 1 to 8, wherein the norm is a weighted norm in which weights are assigned to the d-axis current and the q-axis current.

10. A drive device as described in any one of claims 1 to 9, further comprising: a first coordinate conversion unit that converts the three-phase current vector of the current detected by the current detection unit into an axial current vector in a rotating two-phase coordinate system, which is the current vector, based on the rotor position information; and a second coordinate conversion unit that converts the voltage command, the voltage phase of which has been manipulated by the manipulated variable, into a three-phase voltage command vector, wherein the voltage command determination unit generates the voltage command of the three-phase voltage command vector based on the axial current vector, and the beatless control unit searches for the manipulated variable based on the axial current vector.

11. A compressor drive system comprising: a drive device according to any one of claims 1 to 10; and a compressor driven by the AC motor.

12. A refrigeration cycle device comprising the compressor drive system according to claim 11.

Images