Power conversion devices, motor drive devices, and refrigeration cycle application equipment

Abstract

A power conversion device (200) that drives, in a three-phase sinusoidal wave fashion, a motor (7) that drives a load element having 2n or more poles, where n is an integer equal to or greater than two, and in which the load torque fluctuates periodically, includes: a rectifier unit (3) that rectifies first AC power supplied from an AC power supply (1); a smoothing capacitor (5) connected to an output terminal of the rectifier unit (3); an inverter (30) that is connected across the smoothing capacitor (5) and generates second AC power and outputs it to the motor (7); and a control device (100) that controls operation of the inverter (30) to control driving of the motor (7), whose positional relationship with the mechanical position of the load element is defined, and the control device (100) selects one true estimated mechanical angle phase from n candidates for the estimated mechanical angle phase of the motor (7) using at least one of an estimated speed, an estimated output torque, and a δ-axis current compensation value.

Description

[Technical Field]

[0001] The present disclosure relates to a power conversion device that converts AC power into desired power, a motor drive device, and a refrigeration cycle device. [Background technology]

[0002] Conventionally, in air conditioners and the like equipped with rotary compressors, the operating state of the rotary compressor is monitored, and if an abnormality is detected, control is performed to change the operating frequency of the rotary compressor, etc. For example, Patent Document 1 discloses a technology for performing control to change the operating frequency so that the vanes do not separate when an abnormality in vane separation, in which the piston and vane separate, is detected in a rotary compressor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2024 / 100841 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when detecting an abnormality in vane separation in a rotary compressor, the angle of the crankshaft is used as the rotational angle of the piston. The crankshaft angle corresponds to the mechanical angle phase, which indicates the rotational state of the motor that drives the rotary compressor. Although not explicitly stated in Patent Document 1, the mechanical angle phase of the motor can be easily detected using a sensor or the like. Meanwhile, in recent years, sensorless control, which does not use a sensor to detect the mechanical angle phase of the motor, has been practiced. Sensorless control does not require a sensor to detect the mechanical angle phase of the motor, but it is necessary to estimate the mechanical angle phase of the motor from the detection value of a sensor that monitors the operating state of the motor. In this case, there is a problem in that low accuracy in estimating the mechanical angle phase of the motor can affect subsequent abnormality detection and control of the rotary compressor.

[0005] The present disclosure has been made in view of the above, and has an object to provide a power conversion device that can improve the estimation accuracy of the mechanical angle phase of a motor that drives a rotary compressor. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a power conversion device that uses three-phase sinusoidal waves to drive a motor that has 2n or more poles, where n is an integer equal to or greater than 2, and drives a load element whose load torque fluctuates periodically. The power conversion device includes a rectifier that rectifies first AC power supplied from an AC power supply, a capacitor connected to an output terminal of the rectifier, an inverter connected across the capacitor to generate second AC power and output it to the motor, and a control device that controls operation of the inverter to control driving of the motor, the positional relationship of which with the mechanical position of the load element is defined. The control device selects one true estimated mechanical angle phase from n candidate estimated mechanical angle phases of the motor using at least one of an estimated speed, an estimated output torque, and a δ-axis current compensation value. [Effects of the Invention]

[0007] The power conversion device according to the present disclosure has an advantage that it is possible to improve the accuracy of estimating the mechanical angle phase of the motor that drives the rotary compressor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a configuration example of a power conversion device according to a first embodiment. [Figure 2] FIG. 1 is a block diagram showing a configuration example of an inverter included in a power conversion device according to a first embodiment. [Figure 3] FIG. 1 is a diagram showing a configuration example of a compressor connected to a power conversion device according to a first embodiment; [Figure 4] FIG. 10 is a diagram showing a state of vane separation occurring in a compressor connected to the power conversion device according to the first embodiment. [Figure 5] FIG. 1 is a diagram showing an example of the relationship between the electrical angle phase and the mechanical angle phase of a motor for which the control device of the power conversion device according to the first embodiment estimates the mechanical angle phase; [Figure 6] FIG. 1 is a block diagram showing a configuration example of a control device provided in a power conversion device according to a first embodiment. [Figure 7] FIG. 1 is a diagram for explaining a method in which a voltage command value calculation unit included in the control device for the power conversion device according to the first embodiment estimates a true estimated mechanical angle phase. [Figure 8] FIG. 1 is a block diagram showing a configuration example of a voltage command value calculation unit included in a control device for a power conversion device according to a first embodiment. [Figure 9] FIG. 1 is a block diagram showing a configuration example of a vibration suppression control unit included in a voltage command value calculation unit according to a first embodiment. [Figure 10] FIG. 10 is a diagram showing calculation contents in a mechanical angle phase estimation unit included in a voltage command value calculation unit according to the first embodiment. [Figure 11] 1 is a flowchart showing the operation of a mechanical angle phase estimation unit included in a voltage command value calculation unit according to the first embodiment. [Figure 12] FIG. 10 is a diagram showing calculation contents in a vane separation suppression control unit provided in the voltage command value calculation unit according to the first embodiment. [Figure 13] FIG. 1 is a diagram showing an example of a hardware configuration for realizing a control device provided in a power conversion device according to a first embodiment. [Figure 14] FIG. 10 is a diagram for explaining a method in which a voltage command value calculation unit included in a control device for a power conversion device according to a second embodiment estimates a true estimated mechanical angle phase. [Figure 15] FIG. 10 is a block diagram showing a configuration example of a voltage command value calculation unit included in a control device for a power conversion device according to a second embodiment. [Figure 16] FIG. 10 is a diagram showing calculation contents in a mechanical angle phase estimation unit included in a voltage command value calculation unit according to a second embodiment. [Figure 17] 10 is a flowchart showing the operation of a mechanical angle phase estimation unit included in a voltage command value calculation unit according to a second embodiment. [Figure 18] FIG. 10 is a diagram for explaining a method in which a voltage command value calculation unit included in a control device for a power conversion device according to a third embodiment estimates a true estimated mechanical angle phase. [Figure 19] FIG. 10 is a block diagram showing a configuration example of a voltage command value calculation unit included in a control device for a power conversion device according to a third embodiment. [Figure 20] FIG. 11 is a diagram showing calculation contents in a mechanical angle phase estimation unit included in a voltage command value calculation unit according to a third embodiment. [Figure 21] 10 is a flowchart showing the operation of a mechanical angle phase estimation unit included in a voltage command value calculation unit according to a third embodiment. [Figure 22] FIG. 10 is a diagram showing a configuration example of a refrigeration cycle application device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a power conversion device, a motor drive device, and a refrigeration cycle applied device according to embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] Embodiment 1 FIG. 1 is a block diagram showing a configuration example of a power conversion device 200 according to the first embodiment. FIG. 2 is a block diagram showing a configuration example of an inverter 30 included in the power conversion device 200 according to the first embodiment. The power conversion device 200 is connected to an AC power source 1 and a compressor 8. The power conversion device 200 converts first AC power of a power source voltage Vs supplied from the AC power source 1 into second AC power having a desired amplitude and phase, and supplies the second AC power to the compressor 8. The power conversion device 200 includes a reactor 2, a rectifier 3, a smoothing capacitor 5, an inverter 30, a bus voltage detection unit 10, a load current detection unit 40, a power source current detection unit 50, and a control device 100. The power conversion device 200 and a motor 7 included in the compressor 8 form a motor drive device 400.

[0011] The power supply current detection unit 50 is a detection unit that detects the power supply current Iin of the first AC power supplied from the AC power supply 1 to the power conversion device 200 and outputs the detected current value to the control device 100. The reactor 2 is connected between the AC power supply 1 and the rectification unit 3. The rectification unit 3 has a bridge circuit formed by rectification elements 131 to 134, and rectifies and outputs the first AC power of the power supply voltage Vs supplied from the AC power supply 1. The rectification unit 3 performs full-wave rectification.

[0012] The smoothing capacitor 5 is connected to the output terminal of the rectifier 3 and is a smoothing element that smooths the power rectified by the rectifier 3. The smoothing capacitor 5 may be, for example, an electrolytic capacitor or a film capacitor. The smoothing capacitor 5 has a capacitance sufficient to smooth the power rectified by the rectifier 3. The voltage generated across the smoothing capacitor 5 does not have the full-wave rectified waveform of the AC power source 1, but rather has a waveform in which a DC component is superimposed with a voltage ripple corresponding to the frequency of the AC power source 1, and does not pulsate significantly. The frequency of this voltage ripple is mainly twice the frequency of the power supply voltage Vs when the AC power source 1 is single-phase, and six times the frequency when the AC power source 1 is three-phase. When the power input from the AC power source 1 and the power output from the inverter 30 do not change, the amplitude of this voltage ripple is determined by the capacitance of the smoothing capacitor 5. For example, the voltage ripple generated across the smoothing capacitor 5 pulsates within a range in which the maximum value is less than twice the minimum value.

[0013] The bus voltage detection unit 10 is a detection unit that detects the voltage across the smoothing capacitor 5, i.e., the voltage between the DC buses 12a and 12b, as the bus voltage Vdc and outputs the detected voltage value to the control device 100. The load current detection unit 40 is a detection unit that detects the load current Idc, which is a DC current flowing from the smoothing capacitor 5 to the inverter 30, and outputs the detected current value to the control device 100.

[0014] The inverter 30 is connected to both ends of the smoothing capacitor 5 and converts the power output from the rectifier 3 and the smoothing capacitor 5 into second AC power having a desired amplitude and phase, i.e., generates the second AC power, and outputs it to the motor 7 included in the compressor 8. Specifically, the inverter 30 receives the bus voltage Vdc and generates a three-phase AC voltage with a variable frequency and voltage value, which is supplied to the motor 7 via output lines 331 to 333. As shown in FIG. 2, the inverter 30 includes an inverter main circuit 310 and a drive circuit 350. Input terminals of the inverter main circuit 310 are connected to the DC buses 12a and 12b. The inverter main circuit 310 includes switching elements 311 to 316. Reflux rectifier elements 321 to 326 are connected in anti-parallel to the switching elements 311 to 316, respectively.

[0015] The drive circuit 350 generates drive signals Sr1-Sr6 based on PWM (Pulse Width Modulation) signals Sm1-Sm6 output from the control device 100. The drive circuit 350 controls the on / off of the switching elements 311-316 using the drive signals Sr1-Sr6. This enables the inverter 30 to supply a three-phase AC voltage with variable frequency and voltage to the motor 7 via the output lines 331-333.

[0016] The PWM signals Sm1 to Sm6 are signals having a signal level of a logic circuit, i.e., a magnitude of 0V to 5V. The PWM signals Sm1 to Sm6 are signals with a reference potential equal to the ground potential of the control device 100. On the other hand, the drive signals Sr1 to Sr6 are signals having a voltage level required to control the switching elements 311 to 316, for example, a magnitude of -15V to +15V. The drive signals Sr1 to Sr6 are signals with a reference potential equal to the potential of the negative terminal, i.e., the emitter terminal, of the corresponding switching elements 311 to 316.

[0017] The compressor 8 includes a motor 7 for driving the compressor. The motor 7 drives a load element whose load torque fluctuates periodically. The motor 7 rotates in accordance with the amplitude and phase of the second AC power supplied from the inverter 30 to perform compression. For example, when the compressor 8 is a hermetic compressor used in an air conditioner or the like, the load torque of the compressor 8 can often be considered a constant torque load. In this embodiment, the motor 7 has 2n or more poles, where n is an integer greater than or equal to 2. While FIG. 1 illustrates the motor 7 with a Y-connection in the motor winding, this is merely an example and is not limiting. The motor winding of the motor 7 may be a Δ-connection or may be switchable between a Y-connection and a Δ-connection. In this embodiment, the compressor 8 is assumed to be a rotary compressor. The rotary compressor may be a single rotary compressor or a twin rotary compressor.

[0018] Note that the arrangement of the components of the power conversion device 200 shown in Fig. 1 is an example, and the arrangement of the components is not limited to the example shown in Fig. 1. For example, the reactor 2 may be arranged after the rectifier 3. Furthermore, the power conversion device 200 may include a booster unit, or the rectifier 3 may be given the function of a booster unit. In the following description, the bus voltage detection unit 10, the load current detection unit 40, and the power supply current detection unit 50 may be collectively referred to as detection units. Furthermore, the voltage value detected by the bus voltage detection unit 10, the current value detected by the load current detection unit 40, and the current value detected by the power supply current detection unit 50 may be referred to as detection values.

[0019] The control device 100 acquires a bus voltage Vdc from a bus voltage detection unit 10, a load current Idc from a load current detection unit 40, and a power supply current Iin from a power supply current detection unit 50. The control device 100 uses the detection values ​​detected by each detection unit to control the operation of the inverter main circuit 310, specifically, the on / off of switching elements 311 to 316 of the inverter main circuit 310. In this embodiment, the control device 100 controls the operation of the inverter 30 to suppress vane separation, which is the separation of the vane from the rolling piston, of the compressor 8, which is a rotary compressor, as described below. The control device 100 also controls the operation of the inverter 30 to drive the motor 7 with a three-phase sine wave. The control device 100 controls the operation of the inverter 30 to control the drive of the motor 7, whose positional relationship with the mechanical position of the load element is specified. Note that the control device 100 does not need to use all of the detection values ​​acquired from each detection unit, and may perform control using only some of the detection values.

[0020] Next, a description will be given of a characteristic operation of the control device 100 in this embodiment. When the power conversion device 200 outputs the second AC power to the motor 7 provided in the compressor 8, the control device 100 performs constant current load control to control the operation of the inverter 30 so that the rotation speed of the motor 7 becomes a desired rotation speed. At this time, as described above, the control device 100 controls the operation of the inverter 30 so as to suppress vane separation, in which the vane separates from the rolling piston in the compressor 8, which is a rotary compressor.

[0021] FIG. 3 is a diagram illustrating a configuration example of the compressor 8 connected to the power conversion apparatus 200 according to the first embodiment. FIG. 4 is a diagram illustrating vane separation that occurs in the compressor 8 connected to the power conversion apparatus 200 according to the first embodiment. As illustrated in FIGS. 3 and 4 , the compressor 8 includes a vane 81, a rolling piston 82, and a vane spring 83. The vane 81, the rolling piston 82, and the vane spring 83 are similar to those included in a typical rotary compressor. Although not illustrated, the rotational position of the rolling piston 82 when the tip of the vane 81 is farthest from the rotation axis of the rolling piston 82 while the vane 81 is in contact with the rolling piston 82 is defined as a mechanical angle phase of 0°. FIG. 4( a) illustrates a state in which the mechanical angle phase of the rolling piston 82 is approximately 90°, FIG. 4( b) illustrates a state in which the mechanical angle phase of the rolling piston 82 is approximately 135°, and FIG. 4( c) illustrates a state in which the mechanical angle phase of the rolling piston 82 is approximately 180°. The mechanical angle phase of the rolling piston 82 is 0° when the rolling piston 82 is moved back approximately 90° counterclockwise from the state shown in FIG. 4(a).

[0022] The rolling piston 82 is rotated by the motor 7. Normally, the vane 81 is pressed against the rolling piston 82 by the vane spring 83 and is in contact with the rolling piston 82, for example, as shown in FIG. 4(a). However, if for some reason the vane 81 is no longer able to follow the rotation of the rolling piston 82, vane separation occurs as shown in FIG. 4(b). Thereafter, when the vane 81 re-contacts the rolling piston 82 due to the pressing force of the vane spring 83 at the position of the rolling piston 82 shown in FIG. 4(c), a metallic collision sound is generated at the time of re-contact. This metallic collision sound causes noise. Therefore, in this embodiment, the control device 100 of the power conversion device 200 controls the operation of the compressor 8 to suppress vane separation.

[0023] Here, in order for the control device 100 to suppress vane separation by controlling the operation of the compressor 8, the control device 100 needs to accurately estimate the rotational position of the rolling piston 82 provided in the compressor 8, i.e., the rotational position of the motor 7 that rotates the rolling piston 82. Below, an operation of the control device 100 to estimate the rotational position of the motor 7, i.e., the mechanical angle phase of the motor 7, will be described.

[0024] FIG. 5 is a diagram illustrating an example of the relationship between the electrical angle phase and the mechanical angle phase of the motor 7, the mechanical angle phase of which is estimated by the control device 100 of the power conversion device 200 according to the first embodiment. In FIG. 5, the electrical angle phase is the estimated electrical angle phase, and the mechanical angle phase is the actual mechanical angle phase. For example, when the number of pole pairs of the motor 7 is n=3, in sensorless control that does not generate an axis error, there are three times during one period of the mechanical angle phase of the motor 7 when the electrical angle phase of the motor 7 becomes 0°. In the example of FIG. 5, these three times are a, b, and c. Although not shown in FIG. 5, the point immediately to the right of c at which the estimated mechanical angle phase becomes 0° corresponds to a in the next period of the mechanical angle phase of the motor 7.

[0025] The actual mechanical angle phase is determined by setting a, b, or c to 0°. In other words, when the number of pole pairs n is 3, the mechanical angle phase can be estimated by deriving one correct answer from three candidates. Furthermore, when the compressor 8 is a single rotary compressor, the invariant relationship between phase and torque is "When the mechanical angle phase is 0°, i.e., at top dead center, the load torque is approximately 0 Nm." When the compressor 8 is a single rotary compressor, even if various conditions change, such as the rotation speed of the rolling piston 82 and the differential pressure inside the compressor 8, if there is an invariant relationship between the mechanical angle phase and the load torque, it is possible to determine which of a, b, or c corresponds to the mechanical angle phase of 0° from the phase information based on this invariant relationship. Regarding the invariant relationship between the mechanical angle phase and the load torque, when the compressor 8 is a single rotary compressor, the invariant relationship between the mechanical angle phase and the load torque is "When the mechanical angle phase is 0°, i.e., at top dead center, the load torque is approximately 0 Nm." The control device 100 utilizes these characteristics to estimate the mechanical angle phase of the motor 7.

[0026] The following describes the detailed configuration and operation of the control device 100. Fig. 6 is a block diagram showing an example configuration of the control device 100 included in the power conversion device 200 according to the first embodiment. The control device 100 includes an operation control unit 102 and an inverter control unit 110.

[0027] The operation control unit 102 acquires command information Qe from the refrigeration cycle-applied equipment or the like. When the refrigeration cycle-applied equipment is an air conditioner, the command information Qe is information based on, for example, a temperature detected by a temperature sensor (not shown), information indicating a set temperature instructed from a remote control (not shown) which is an operation unit, information on the selection of an operation mode, and instruction information for starting and ending operation. The operation mode is, for example, heating, cooling, dehumidification, etc. Based on the command information Qe, the operation control unit 102 acquires a frequency command value ωe for generating a voltage command value which is a command value for the voltage to be applied to the motor 7. * The operation control unit 102 generates the frequency command value ωe * The rotational angular velocity command value ωm * can be obtained by multiplying the frequency command value ωe by the number n of pole pairs of the motor 7. Furthermore, the operation control unit 102 generates a stop signal St, which is a signal for stopping the operation of the inverter 30, based on the command information Qe. The operation control unit 102 generates a frequency command value ωe * to the voltage command value calculation unit 115 of the inverter control unit 110, and outputs a stop signal St to the PWM signal generation unit 118 of the inverter control unit 110.

[0028] The inverter control unit 110 includes a current restoration unit 111, a three-phase to two-phase conversion unit 112, a γ-axis current command value generation unit 113, a voltage command value calculation unit 115, an electrical phase calculation unit 116, a two-phase to three-phase conversion unit 117, and a PWM signal generation unit 118.

[0029] The current restoration unit 111 restores the phase currents iu, iv, and iw flowing through the motor 7 based on the load current Idc detected by the load current detection unit 40. The current restoration unit 111 samples the load current Idc detected by the load current detection unit 40 at timings determined based on the PWM signals Sm1 to Sm6 generated by the PWM signal generation unit 118, thereby restoring the phase currents iu, iv, and iw.

[0030] The 3-to-2 phase conversion unit 112 converts the phase currents iu, iv, and iw restored by the current restoration unit 111 into a γ-axis current Iγ, which is an excitation current, and a δ-axis current Iδ, which is a torque current, i.e., into current values ​​in the rotating coordinate system of the γδ axes, using the electrical phase θe generated by the electrical phase calculation unit 116, which will be described later.

[0031] The γ-axis current command value generating unit 113 generates a γ-axis current command value Iγ in the rotating coordinate system of the γδ axes. * Specifically, the γ-axis current command value generating unit 113 generates a γ-axis current command value Vγ based on the δ-axis current Iδ, the bus voltage Vdc, and the γ-axis voltage command value Vγ * and the δ-axis voltage command value Vδ * Based on this, the optimum γ-axis current command value Iγ that will be most efficient for driving the motor 7 is calculated. * The γ-axis current command value generating unit 113 calculates the δ-axis current Iδ, the bus voltage Vdc, and the γ-axis voltage command value Vγ * , and the δ-axis voltage command value Vδ * Based on this, the γ-axis current command value Iγ is set to a current phase βm at which the output torque of the motor 7 is equal to or greater than a specified value or is at its maximum, i.e., the current value is equal to or less than a specified value or is at its minimum. * Here, the specified γ-axis current value generating unit 113 outputs the specified γ-axis current value Iγ based on the δ-axis current Iδ and the like. * However, this is merely an example and the present invention is not limited to this. The γ-axis current command value generating unit 113 calculates the γ-axis current Iγ and the frequency command value ωe * Based on these factors, the γ-axis current command value Iγ * The γ-axis current command value generating unit 113 can obtain the γ-axis current command value Iγ by using the flux-weakening control or the like. * may be determined.

[0032] The voltage command value calculation unit 115 calculates the frequency command value ωe obtained from the operation control unit 102. * the γ-axis current Iγ and the δ-axis current Iδ acquired from the three-phase to two-phase conversion unit 112, and the γ-axis current command value Iγ acquired from the γ-axis current command value generation unit 113. * Based on this, the γ-axis voltage command value Vγ * and the δ-axis voltage command value Vδ * Furthermore, the voltage command value calculation unit 115 generates the γ-axis voltage command value Vγ * and the δ-axis voltage command value Vδ * The voltage command value calculation unit 115 estimates the frequency estimated value ωest based on the γ-axis current Iγ and the δ-axis current Iδ. Furthermore, the voltage command value calculation unit 115 estimates the true estimated mechanical angle phase θm_real based on the electrical phase θe and the overall δ-axis current command value.

[0033] The electrical phase calculation unit 116 calculates the electrical phase θe by integrating the frequency estimation value ωest acquired from the voltage command value calculation unit 115. The electrical phase calculation unit 116 outputs the electrical phase θe to the three-phase to two-phase conversion unit 112, the two-phase to three-phase conversion unit 117, and the voltage command value calculation unit 115.

[0034] The two-phase to three-phase conversion unit 117 converts the γ-axis voltage command value Vγ * and the δ-axis voltage command value Vδ * , that is, the voltage command value in the two-phase coordinate system is calculated by using the electrical phase θe acquired from the electrical phase calculation unit 116 to calculate the three-phase voltage command value Vu * ,Vv * ,Vw * Convert to.

[0035] The PWM signal generation unit 118 converts the three-phase voltage command value Vu obtained from the two-phase to three-phase conversion unit 117 into a three-phase voltage command value Vu * ,Vv * ,Vw *and the stop signal St acquired from the operation control unit 102. The PWM signal generation unit 118 can also stop the motor 7 by not outputting the PWM signals Sm1 to Sm6 based on the stop signal St.

[0036] Next, an operation of the voltage command value calculation unit 115 to estimate the true estimated mechanical angle phase θm_real will be described. FIG. 7 is a diagram for explaining a method for estimating the true estimated mechanical angle phase θm_real by the voltage command value calculation unit 115 provided in the control device 100 of the power conversion device 200 according to the first embodiment. In FIGS. 7(a) and 7(b), the horizontal axis represents the mechanical angle phase, and the vertical axis represents the load torque. In addition, in FIGS. 7(a) and 7(b), the solid line represents the load torque, and the dotted line represents the ideal output torque value. In addition, FIG. 7(a) shows a case where the conditions are discharge pressure Pd / suction pressure Ps=4 / 1 MPa and 10 rps, and FIG. 7(b) shows a case where the conditions are discharge pressure Pd / suction pressure Ps=1 / 0.5 MPa and 10 rps.

[0037] When the voltage command value calculation unit 115 of the control device 100 is performing vibration suppression control to the maximum extent, which reduces speed vibration at the frequency of one cycle of the mechanical angle phase, that is, when control is performed so that the frequency component of one cycle of the mechanical angle phase of the estimated speed is zero, the load torque will be as shown by the solid line in Fig. 7, while the output torque will be as shown by the dotted line in Fig. 7. In this case, the voltage command value calculation unit 115 of the control device 100 can derive one correct solution from three candidates as shown in Fig. 5 based on the relationship that "the timing when the output torque changes from positive to negative, that is, the electrical angle phase that is closest to 0° at the positive to negative zero crossing, is set to 0° as the estimated mechanical angle phase." In other words, the voltage command value calculation unit 115 of the control device 100 can estimate the mechanical angle phase at the timing when the output torque changes from positive to negative. This is based on the idea that when the voltage command value calculation unit 115 of the control device 100 is performing vibration suppression control to the maximum extent, the load torque and the output torque should essentially match, and therefore the timing of the mechanical angle phase of 0° should match the timing of one of the three electrical angle phases of 0°.

[0038] In the case of Fig. 7(a), if the zero-cross phase of the output torque is 6°, 6° is sufficiently smaller than 120°, which is obtained by dividing 360° by n = 3, and therefore no false detection of mechanical angle phase = 0° occurs. Also, in the case of Fig. 7(b), if the zero-cross phase of the output torque is |360-353| = 7°, 7° is sufficiently smaller than 120°, which is obtained by dividing 360° by n = 3, and therefore no false detection of mechanical angle phase = 0° occurs.

[0039] The configuration and operation of the voltage command value calculation unit 115 that performs the above-mentioned estimation will be described in detail. Fig. 8 is a block diagram showing an example configuration of the voltage command value calculation unit 115 included in the control device 100 of the power conversion device 200 according to the first embodiment. The voltage command value calculation unit 115 includes a frequency estimation unit 501, addition and subtraction units 502, 504, 505, 509, and 513, a speed control unit 503, a γ-axis current control unit 506, a δ-axis current control unit 507, multiplication units 508, 510, and 512, addition units 511 and 516, a vibration suppression control unit 514, a vane separation suppression control unit 515, and a mechanical angle phase estimation unit 520.

[0040] The frequency estimation unit 501 estimates the γ-axis current Iγ, the δ-axis current Iδ, and the γ-axis voltage command value Vγ * and the δ-axis voltage command value Vδ * The frequency of the voltage supplied to the motor 7 is estimated based on the frequency command value ωe and output as a frequency estimate value ωest. Note that the frequency estimate value ωest output from the frequency estimator 501 to the outside of the voltage command value calculator 115 in FIG. 8 is the frequency estimate value ωest output from the voltage command value calculator 115 to the electrical phase calculator 116 in FIG. 6. The adder / subtractor 502 estimates the frequency of the voltage supplied to the motor 7 based on the frequency command value ωe * The frequency command value ωe is calculated by subtracting the frequency estimate ωest from * and the frequency estimated value ωest, and outputs the frequency deviation del_ω.

[0041] The speed control unit 503 calculates the δ-axis current command value Iδ based on the frequency deviation del_ω. * δ-axis current command value Iδ is calculated and output. *is the command value of the δ-axis current Iδ at which the frequency deviation del_ω becomes zero, that is, the frequency command value ωe * is a command value of the δ-axis current Iδ for making the estimated frequency value ωest coincide with the estimated frequency value ωest. The speed control unit 503 is, for example, a proportional-integral (PI) controller, but is not limited to this.

[0042] The adder 516 calculates the δ-axis current command value Iδ output from the speed controller 503. * and the δ-axis current compensation value Iδ_trq output from the vibration suppression control unit 514. * and the δ-axis current compensation value Iδ_VANE output from the vane separation suppression control unit 515. * and are added together and output.

[0043] The adder / subtractor 504 calculates the γ-axis current command value Iγ * The γ-axis current command value Iγ is calculated by subtracting the γ-axis current Iγ from * and the γ-axis current Iγ. The γ-axis current control unit 506 is configured, for example, by a PI controller, and outputs the deviation between the γ-axis current command value Iγ * and the γ-axis current Iγ to converge to zero. * Output.

[0044] The adder / subtractor 505 subtracts the δ-axis current Iδ from the output of the adder 516 and outputs the deviation between the output of the adder 516 and the δ-axis current Iδ. The δ-axis current controller 507 is configured by, for example, a PI controller, and operates to converge the deviation between the output of the adder 516 and the δ-axis current Iδ to zero. The δ-axis current controller 507 calculates the first δ-axis voltage command value Vδfb * Output.

[0045] The multiplier 508 multiplies the output of the adder 516 by the δ-axis inductance Lδ of the motor 7 and the frequency estimate value ωest to obtain a first γ-axis voltage command value Vγfb * Compensation value Vγff * The adder / subtractor 509 calculates and outputs the first γ-axis voltage command value Vγfb * to the compensation value Vγff *to obtain the first γ-axis voltage command value Vγfb * and the compensation value Vγff * Deviation from (Vγfb * -Vγff * ) is calculated as the γ-axis voltage command value Vγ * Output as

[0046] The multiplication unit 510 multiplies the γ-axis current command value Iγ * The adder 511 multiplies the output from the multiplier 510 by the γ-axis inductance Lγ of the motor 7 and outputs the result. The adder 511 adds the magnetic flux linkage vector φf of the motor 7 to the output from the multiplier 510. The multiplier 512 multiplies the output from the adder 511 by the frequency estimation value ωest to obtain a first δ-axis voltage command value Vδfb * Compensation value Vδff * The adder / subtractor 513 calculates and outputs the first δ-axis voltage command value Vδfb * to the compensation value Vδff * to obtain the first δ-axis voltage command value Vδfb * and compensation value Vδff * Deviation from (Vδfb * -Vδff * ) is calculated as the δ-axis voltage command value Vδ * Output as

[0047] 9 is a block diagram showing an example of the configuration of vibration suppression control unit 514 included in voltage command value calculation unit 115 according to Embodiment 1. Vibration suppression control unit 514 includes calculation unit 550, cosine calculation unit 551, sine calculation unit 552, multiplication units 553 and 554, low-pass filters 555 and 556, addition and subtraction units 557 and 558, frequency control units 559 and 560, multiplication units 561 and 562, and an addition unit 563.

[0048] The calculation unit 550 integrates the frequency estimate value ωest and divides it by the number of pole pairs n to calculate the mechanical angle phase θmn that indicates the rotational position of the motor 7. The cosine calculation unit 551 calculates the cosine cosθmn based on the mechanical angle phase θmn. The sine calculation unit 552 calculates the sine sinθmn based on the mechanical angle phase θmn.

[0049] Multiplication unit 553 multiplies frequency estimation value ωest by cosine cosθmn to calculate a cosine component ωest·cosθmn of frequency estimation value ωest. Multiplication unit 554 multiplies frequency estimation value ωest by sine sinθmn to calculate a sine component ωest·sinθmn of frequency estimation value ωest. The cosine component ωest·cosθmn and sine component ωest·sinθmn calculated by multiplication units 553 and 554 contain not only a pulsating component with a frequency of ωmn but also pulsating components with frequencies higher than ωmn, i.e., harmonic components.

[0050] The low-pass filters 555 and 556 are first-order lag filters whose transfer function is expressed as 1 / (1+s·Tf). Tf is a time constant and is determined so as to remove pulsating components of frequencies higher than the frequency ωmn. Note that "removal" includes the case where a portion of the pulsating components is attenuated, i.e., reduced. The time constant Tf may be set by the operation control unit 102 based on a speed command and notified to the low-pass filters 555 and 556 by the operation control unit 102, or may be stored by the low-pass filters 555 and 556. The first-order lag filter is just one example of the low-pass filters 555 and 556, and a moving average filter or the like may also be used. The type of filter is not limited as long as it can remove pulsating components on the high-frequency side.

[0051] The low-pass filter 555 performs low-pass filtering on the cosine component ω·cosθ to remove pulsating components of frequencies higher than ω, and outputs the low-frequency component ωcos, which is a direct current quantity representing the cosine component of the frequency ω of the pulsating components of the frequency estimate ω.

[0052] The low-pass filter 556 performs low-pass filtering on the sine component ω·sinθ to remove pulsating components of frequencies higher than ω, and outputs the low-frequency component ωsin, which is a direct current quantity representing the sine component of the frequency ω of the pulsating components of the frequency estimate ω.

[0053] Addition / subtraction unit 557 calculates the difference (ωestcos−0) between the low frequency component ωestcos output from low pass filter 555 and 0. Addition / subtraction unit 558 calculates the difference (ωestsin−0) between the low frequency component ωestsin output from low pass filter 556 and 0.

[0054] The frequency control unit 559 performs proportional integral calculation on the difference (ωestcos-0) calculated by the addition / subtraction unit 557 to calculate the cosine component Iδtrqcos of the current command value that brings the difference (ωestcos-0) closer to zero. By generating the cosine component Iδtrqcos in this manner, the frequency control unit 559 performs control to make the low frequency component ωestcos equal to zero.

[0055] The frequency control unit 560 performs a proportional-plus-integral operation on the difference (ωestsin-0) calculated by the addition / subtraction unit 558 to calculate a sine component Iδtrqsin of a current command value that brings the difference (ωestsin-0) closer to zero. By generating the sine component Iδtrqsin in this manner, the frequency control unit 560 performs control to make the low-frequency component ωestsin equal to zero.

[0056] Multiplication section 561 generates Iδtrqcos·cosθmn by multiplying cosine component Iδtrqcos output from frequency control section 559 by cosine cosθmn. Iδtrqcos·cosθmn is an AC component having frequency n·ωest.

[0057] Multiplication section 562 generates Iδtrqsin·sinθmn by multiplying sine component Iδtrqsin output from frequency control section 560 by sine sinθmn. Iδtrqsin·sinθmn is an AC component having frequency n·ωest.

[0058] The adder 563 obtains the sum of the AC component Iδtrqcos·cosθmn output from the multiplier 561 and the AC component Iδtrqsin·sinθmn output from the multiplier 562. The vibration suppression control unit 514 converts the value obtained by the adder 563 into a δ-axis current compensation value Iδ_trq for vibration suppression control. * Output as

[0059] FIG. 10 is a diagram showing the calculation contents in the mechanical angle phase estimator 520 included in the voltage command value calculator 115 according to the first embodiment. FIG. 11 is a flowchart showing the operation of the mechanical angle phase estimator 520 included in the voltage command value calculator 115 according to the first embodiment. The mechanical angle phase estimator 520 divides the electrical phase θe acquired from the electrical phase calculator 116 by the number of pole pairs n=3 to convert it into an estimated mechanical angle phase θm (step S11). The mechanical angle phase estimator 520 calculates an estimated mechanical angle phase θm±120° to generate three types of estimated mechanical angle phases including the estimated mechanical angle phase θm (step S12). The three types of estimated mechanical angle phases are the estimated mechanical angle phase θm, the estimated mechanical angle phase θm+120°, and the estimated mechanical angle phase θm−120°. Strictly speaking, the estimated mechanical angle phase θm is obtained by the conversion process in the previous stage. The mechanical angle phase estimator 520 performs limit processing on the three types of estimated mechanical angle phases so that they fall within the range of 0 to 2π (step S13). In addition, the mechanical angle phase estimator 520 calculates the overall δ-axis current command value Iδ_all, which is the output from the adder 516. *by the number of pole pairs n=3 and a specified induced voltage constant to calculate an estimated output torque (step S14). The mechanical angle phase estimator 520 selects, based on the three types of estimated mechanical angle phases after limit processing and the estimated output torque, one of the three types of estimated mechanical angle phases at 0° after limit processing that is closest to the timing at which the estimated output torque crosses zero as the true estimated mechanical angle phase θm_real (step S15). The mechanical angle phase estimator 520 outputs the selected estimated mechanical angle phase after limit processing to the vane separation suppression controller 515 as the true estimated mechanical angle phase θm_real.

[0060] The vane separation suppression control unit 515 calculates a δ-axis current compensation value Iδ_VANE for vane separation suppression control based on the frequency estimation value ωest acquired from the frequency estimator 501 and the true estimated mechanical angle phase θm_real acquired from the mechanical angle phase estimator 520. * Calculates and outputs.

[0061] 12 is a diagram showing the calculation contents in the vane separation suppression control unit 515 provided in the voltage command value calculation unit 115 according to the first embodiment. Here, an example will be described in which the vane separation suppression control unit 515 performs vane separation suppression control within a range of an estimated mechanical angle phase of 90°±20°. The vane separation suppression control unit 515 adds a phase required to make the mechanical angle phase of the motor 7 90° to the true estimated mechanical angle phase θm_real acquired from the mechanical angle phase estimation unit 520, and calculates Theta Iδ_90 Theta Iδ_90 is for positioning the rolling piston 82 at a 90° position. The vane separation suppression control unit 515 converts the frequency estimation value ωest acquired from the frequency estimation unit 501 into a mechanical angular velocity, and then integrates it to convert it into a mechanical angle phase, and applies a phase limiter to obtain the current estimated mechanical angle phase Theta Iδ_ωest_m The vane separation suppression control unit 515 obtains Theta Iδ_90 and Theta Iδ_ωest_m Using Theta Iδ_ωest_m Theta Iδ_90 ±20° range, i.e., Theta Iδ_ωest_mWhen the angle is in the range of 70° to 110°, the δ-axis current compensation value Iδ_VANE for the vane separation suppression control is * The vane separation suppression control unit 515 outputs Theta Iδ_ωest_m When the angle is outside the range of 70° to 110°, the δ-axis current compensation value Iδ_VANE for the vane separation suppression control is * Do not output.

[0062] 12 is one example. The vane separation suppression control by the vane separation suppression control unit 515 may perform the vane separation suppression control in a range of the mechanical angle phase of the motor 7 different from that described above. Furthermore, the mechanical angle phase estimator 520 may output the true estimated mechanical angle phase θm_real to a component other than the vane separation suppression control unit 515, or may output it to another component together with the vane separation suppression control unit 515. In this case, the other component may be external to the voltage command value calculator 115. The same applies to the following embodiments.

[0063] In this way, in the power conversion device 200, the control device 100 uses the estimated output torque to select one true estimated mechanical angle phase from the n estimated mechanical angle phase candidates of the motor 7. At the zero crossing timing when the estimated output torque of the motor 7 changes from positive to negative, the control device 100 selects the one of the n estimated mechanical angle phase candidates that is closest to 0° as the true estimated mechanical angle phase.

[0064] Next, a description will be given of the hardware configuration of the control device 100 included in the power conversion device 200. Fig. 13 is a diagram illustrating an example of a hardware configuration that realizes the control device 100 included in the power conversion device 200 according to the first embodiment. The control device 100 is realized by a processor 91 and a memory 92.

[0065] The processor 91 is a CPU (Central Processing Unit, also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). 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).

[0066] As described above, according to this embodiment, in the power conversion device 200, the control device 100 selects, as the true estimated mechanical angle phase, the one of the n estimated mechanical angle phase candidates that is closest to 0° at the zero crossing timing when the estimated output torque of the motor 7 changes from positive to negative. This enables the power conversion device 200 to improve the estimation accuracy of the mechanical angle phase of the motor 7 that drives the rotary compressor, which is the compressor 8.

[0067] Embodiment 2 In the second embodiment, a method will be described in which the control device 100 selects one true estimated mechanical angle phase from n candidates for the estimated mechanical angle phase of the motor 7 using a method different from that in the first embodiment.

[0068] In the second embodiment, the configuration of the power conversion device 200 is the same as the configuration of the power conversion device 200 of the first embodiment shown in Fig. 1. In addition, in the second embodiment, the configuration of the control device 100 is the same as the configuration of the control device 100 of the first embodiment shown in Fig. 6.

[0069] Next, the operation of the voltage command value calculation unit 115 to estimate the true estimated mechanical angle phase θm_real will be described. FIG. 14 is a diagram for explaining a method for estimating the true estimated mechanical angle phase θm_real by the voltage command value calculation unit 115 provided in the control device 100 of the power conversion device 200 according to the second embodiment. In FIGS. 14(a) and 14(b), the horizontal axis represents the mechanical angle phase, and the vertical axis represents the load torque. In FIG. 14(a), the solid line represents the load torque, the dotted line represents the ideal output torque, and the dashed-dotted line represents the AC component of the output torque. In FIG. 14(b), the solid line represents the load torque, and the dashed-dotted line represents the AC component of the output torque. In addition, FIG. 14(a) shows the case where the conditions are discharge pressure Pd / suction pressure Ps = 4 / 1 MPa and 10 rps, and FIG. 14(b) shows the case where the conditions are discharge pressure Pd / suction pressure Ps = 1 / 0.5 MPa and 10 rps.

[0070] In the first embodiment, it is assumed that the voltage command value calculation unit 115 is performing vibration suppression control to the maximum extent. However, in the second embodiment, it is assumed that the voltage command value calculation unit 115 is performing vibration suppression control but not to the maximum extent. The voltage command value calculation unit 115 can estimate a true estimated mechanical angle phase even when vibration suppression control is not being performed at the maximum extent. Here, the voltage command value calculation unit 115 uses the frequency component of one cycle of the mechanical angle phase of the output torque. The voltage command value calculation unit 115 can derive one correct solution from three candidates as shown in FIG. 5 based on the relationship that the mechanical angle phase of 0°, at which the load torque becomes 0, exists in the range from 0 to the maximum negative value of the δ-axis current command value of the vibration suppression control, i.e., in the range of the mechanical angle phase of 90°. The voltage command value calculation unit 115 selects a true estimated mechanical angle phase θm_real from three types of estimated mechanical angle phases within the estimated mechanical angle phase determination range shown in FIG. 14, i.e., the range of the mechanical angle phase of 90°. The voltage command value calculation unit 115 will not make an erroneous determination because the estimated mechanical angle phase determination range is 90°, which is narrower than 120° obtained by dividing 360° by the number of pole pairs n=3. This is because it is unlikely that the optimal phase for vibration suppression control will deviate by 120°-90°=30° even if there is variation in the constants of the motor 7. Note that, in this case, the estimated mechanical angle phase determination range of 90° is narrower than 120° obtained by dividing 360° by the number of pole pairs n=3, so no erroneous detection will occur, but it is conceivable that an erroneous detection will occur as the number of pole pairs n increases.

[0071] The configuration and operation of the voltage command value calculation unit 115 that performs the above-mentioned estimation will be described in detail. Fig. 15 is a block diagram showing an example of the configuration of the voltage command value calculation unit 115 included in the control device 100 of the power conversion device 200 according to the second embodiment. The voltage command value calculation unit 115 of the second embodiment has a configuration similar to that of the voltage command value calculation unit 115 of the first embodiment shown in Fig. 8, but differs in that the input to the mechanical angle phase estimator 520 is changed from the output from the adder 516 to the output from the vibration suppression control unit 514. In the voltage command value calculation unit 115 of the second embodiment, the operations other than the mechanical angle phase estimator 520 are similar to those of the voltage command value calculation unit 115 of the first embodiment. Therefore, a description of the operations other than the mechanical angle phase estimator 520 will be omitted.

[0072] Fig. 16 is a diagram showing the calculation contents in the mechanical angle phase estimator 520 included in the voltage command value calculator 115 according to the second embodiment. Fig. 17 is a flowchart showing the operation of the mechanical angle phase estimator 520 included in the voltage command value calculator 115 according to the second embodiment. In the second embodiment, the operation from step S11 to step S13 in the mechanical angle phase estimator 520 is the same as the operation from step S11 to step S13 in the mechanical angle phase estimator 520 according to the first embodiment shown in Fig. 11. The mechanical angle phase estimator 520 calculates three types of estimated mechanical angle phases after limit processing and the δ-axis current compensation value Iδ_trq of vibration suppression control. * Based on this, the δ-axis current compensation value Iδ_trq for vibration suppression control is calculated from the three types of estimated mechanical angle phases of 0° after limit processing. * is selected as the true estimated mechanical angle phase θm_real (step S25).

[0073] In this way, in the power conversion device 200, the control device 100 controls the δ-axis current compensation value Iδ_trq * When vibration suppression control is performed to suppress vibration of the motor 7 by compensating the output torque of the motor 7 so that it matches the load torque of the load element, the control device 100 selects one true estimated mechanical angle phase from the n candidates of the estimated mechanical angle phase of the motor 7 using the δ-axis current compensation value Iδ_trq of the vibration suppression control. *is in the range from 0 to the maximum absolute value in the negative region, one of the n candidates for the estimated mechanical angle phase that has 0° is selected as the true estimated mechanical angle phase.

[0074] As described above, according to this embodiment, in the power conversion device 200, when vibration suppression control is being performed, the control device 100 sets the δ-axis current compensation value Iδ_trq of the vibration suppression control. * is in the range from 0 to the maximum absolute value in the negative region, one of the n candidates for the estimated mechanical angle phase that has 0° is selected as the true estimated mechanical angle phase. Even in this case, the power conversion device 200 can obtain the same effect as in the first embodiment.

[0075] Embodiment 3 In the third embodiment, a method will be described in which the control device 100 selects one true estimated mechanical angle phase from n candidates for the estimated mechanical angle phase of the motor 7 using a method different from that used in the first and second embodiments.

[0076] In the third embodiment, the configuration of the power conversion device 200 is the same as the configuration of the power conversion device 200 of the first embodiment shown in Fig. 1. Also, in the third embodiment, the configuration of the control device 100 is the same as the configuration of the control device 100 of the first embodiment shown in Fig. 6.

[0077] Next, the operation of the voltage command value calculation unit 115 to estimate the estimated true mechanical angle phase θm_real will be described. Fig. 18 is a diagram for explaining a method for the voltage command value calculation unit 115 provided in the control device 100 of the power conversion device 200 according to the third embodiment to estimate the estimated true mechanical angle phase θm_real. Fig. 18(a) shows the estimated speed of the motor 7, Fig. 18(b) shows each current value of the three-phase AC voltage flowing from the inverter 30 to the motor 7, and Fig. 18(c) shows the δ-axis current Iδ and the δ-axis current command value Iδ * 18(d) shows the load torque of the motor 7.

[0078] In the first and second embodiments, it is assumed that the voltage command value calculation unit 115 is performing vibration suppression control. However, in the third embodiment, it is assumed that the voltage command value calculation unit 115 is not performing vibration suppression control. When vibration suppression control is not being performed, the voltage command value calculation unit 115 uses the 1x component of the mechanical angular frequency of the estimated speed of the motor 7. The mechanical angle phase of 0°, at which the load torque becomes 0, exists in the range from the negative peak of the 1x component of the mechanical angular frequency of the estimated speed of the motor 7 to 0, i.e., within a 90° range of the mechanical angle phase. Based on the above relationship, the voltage command value calculation unit 115 can derive one correct solution from three candidates as shown in FIG. 5. The voltage command value calculation unit 115 selects a true estimated mechanical angle phase θm_real from three types of estimated mechanical angle phases within the 90° range of the mechanical angle phase shown on the right side of FIG. 18. The voltage command value calculation unit 115 will not make an erroneous determination because the mechanical angle phase of 90° is narrower than 120° obtained by dividing 360° by the number of pole pairs n = 3. Note that in this case, the mechanical angle phase of 90° is in a range narrower than 120° obtained by dividing 360° by the number of pole pairs n = 3, so no erroneous detection will occur, but it is conceivable that an erroneous detection will occur as the number of pole pairs n increases.

[0079] The configuration and operation of the voltage command value calculation unit 115 that performs the above-mentioned estimation will be described in detail. Fig. 19 is a block diagram showing an example of the configuration of the voltage command value calculation unit 115 provided in the control device 100 of the power conversion device 200 according to the third embodiment. The voltage command value calculation unit 115 according to the third embodiment is obtained by eliminating the vibration suppression control unit 514 from the voltage command value calculation unit 115 according to the first embodiment shown in Fig. 8. Furthermore, in the voltage command value calculation unit 115 according to the third embodiment, compared to the voltage command value calculation unit 115 according to the first embodiment shown in Fig. 8, the input to the mechanical angle phase estimation unit 520 is not the output from the adder 516 but an estimated speed, i.e., a frequency command value ωe * The difference is that the operation of the voltage command value calculation unit 115 according to the third embodiment is the same as that of the voltage command value calculation unit 115 according to the first embodiment, except for the mechanical angle phase estimation unit 520. Therefore, the description of the operation of the units other than the mechanical angle phase estimation unit 520 will be omitted.

[0080] 20 is a diagram showing the calculation contents in the mechanical angle phase estimator 520 included in the voltage command value calculator 115 according to the third embodiment. FIG. 21 is a flowchart showing the operation of the mechanical angle phase estimator 520 included in the voltage command value calculator 115 according to the third embodiment. In the third embodiment, the operations from step S11 to step S13 in the mechanical angle phase estimator 520 are the same as the operations from step S11 to step S13 in the mechanical angle phase estimator 520 according to the first embodiment shown in FIG. 11. The mechanical angle phase estimator 520 calculates a frequency command value ωe * The mechanical angle phase estimator 520 extracts the 1x component of the mechanical angle frequency from the estimated speed (step S34). Of the three types of estimated mechanical angle phases at 0° after limit processing, the mechanical angle phase estimator 520 selects the one in which the 1x component of the mechanical angle frequency of the estimated speed falls within a range from a negative peak to 0 as the true estimated mechanical angle phase θm_real (step S35).

[0081] In this way, in the power conversion device 200, the control device 100 controls the frequency command value ωe * That is, the estimated speed is used to select one true estimated mechanical angle phase from n candidates for the estimated mechanical angle phase of the motor 7. The control device 100 selects, as the true estimated mechanical angle phase, one of the n candidates for the estimated mechanical angle phase that has 0° within the range where the 1x component of the mechanical angle frequency of the estimated speed of the motor 7 goes from its negative peak to 0.

[0082] Considering the first to third embodiments, the control device 100 calculates the estimated speed, the estimated output torque, and the δ-axis current compensation value Iδ_trq * and select one true estimated mechanical angle phase from the n estimated mechanical angle phase candidates of the motor 7 using at least one of them. It can also be said that the control device 100 changes the method for selecting one from the n estimated mechanical angle phase candidates of the motor 7 depending on whether vibration suppression control is being performed or not, that is, depending on the state of vibration suppression control.

[0083] As described above, according to this embodiment, in the power conversion device 200, when vibration suppression control is not being performed, the control device 100 selects, as the true estimated mechanical angle phase, one of n candidates for the estimated mechanical angle phase that has 0° within a range in which the 1x component of the mechanical angular frequency of the estimated speed goes from a negative peak to 0. Even in this case, the power conversion device 200 can obtain the same effect as in the first embodiment.

[0084] Embodiment 4 Fig. 22 is a diagram showing a configuration example of a refrigeration cycle-applied device 900 according to embodiment 4. The refrigeration cycle-applied device 900 according to embodiment 4 includes the power conversion device 200 described in embodiments 1 to 3. The refrigeration cycle-applied device 900 according to embodiment 4 can be applied to products equipped with a refrigeration cycle, such as air conditioners, refrigerators, freezers, and heat pump water heaters. In Fig. 22, components having the same functions as those in embodiment 1 are assigned the same reference numerals as those in embodiment 1.

[0085] The refrigeration cycle applied equipment 900 includes a compressor 8 incorporating the motor 7 in embodiment 1, a four-way valve 902, an indoor heat exchanger 906, an expansion valve 908, and an outdoor heat exchanger 910 attached via refrigerant piping 912.

[0086] Inside the compressor 8, a compression mechanism 904 that compresses the refrigerant and a motor 7 that operates the compression mechanism 904 are provided.

[0087] 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 a motor 7 that is variably controlled in speed.

[0088] 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.

[0089] During cooling operation, as indicated by the dashed arrow, the refrigerant is pressurized by the compression mechanism 904 and sent out, passes through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906 and the four-way valve 902 and returns to the compression mechanism 904.

[0090] During heating operation, the indoor heat exchanger 906 acts as a condenser to release heat, and the outdoor heat exchanger 910 acts as an evaporator to absorb heat. During cooling operation, the outdoor heat exchanger 910 acts as a condenser to release heat, and the indoor heat exchanger 906 acts as an evaporator to absorb heat. The expansion valve 908 decompresses and expands the refrigerant.

[0091] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0092] 1 AC power supply, 2 reactor, 3 rectifier, 5 smoothing capacitor, 7 motor, 8 compressor, 10 bus voltage detection unit, 12a, 12b DC bus, 30 inverter, 40 load current detection unit, 50 power supply current detection unit, 81 vane, 82 rolling piston, 83 vane spring, 91 processor, 92 memory, 100 control device, 102 operation control unit, 110 inverter control unit, 111 current restoration unit, 112 3-phase to 2-phase conversion unit, 113 γ-axis current command value generation unit, 115 voltage command value calculation unit, 116 electrical phase calculation unit, 117 2-phase to 3-phase conversion unit, 118 PWM signal generation unit, 131 to 134, 321 to 326 rectifier element, 200 power conversion device, 310 inverter main circuit, 311 to 316 switching elements, 331 to 333 Output line, 350 drive circuit, 400 motor drive device, 501 frequency estimator, 502, 504, 505, 509, 513, 557, 558 addition / subtraction unit, 503 speed control unit, 506 γ-axis current control unit, 507 δ-axis current control unit, 508, 510, 512, 553, 554, 561, 562 multiplication unit, 511, 516 addition unit, 514 vibration suppression control unit, 515 vane separation suppression control unit, 520 mechanical angle phase estimator, 550 calculation unit, 551 cosine calculation unit, 552 sine calculation unit, 555, 556 low-pass filter, 559, 560 frequency control unit, 563 addition unit, 900 refrigeration cycle applied equipment, 902 four-way valve, 904 compression mechanism, 906 indoor heat exchanger, 908 Expansion valve, 910 Outdoor heat exchanger, 912 Refrigerant piping.

Claims

1. A power conversion device that drives a motor with three-phase sinusoidal waves, the motor having 2n or more poles, where n is an integer of 2 or more, and driving a load element whose load torque fluctuates periodically, a rectification unit that rectifies first AC power supplied from an AC power supply; a capacitor connected to an output terminal of the rectifier; an inverter connected to both ends of the capacitor to generate second AC power and output the second AC power to the motor; a control device that controls the operation of the inverter to control the driving of the motor, the positional relationship of which with respect to the mechanical position of the load element is defined; Equipped with the control device selects one true estimated mechanical angle phase from n candidates of estimated mechanical angle phases of the motor using at least one of an estimated speed, an estimated output torque, and a δ-axis current compensation value; Power conversion device.

2. the control device changes a method for selecting one of the n candidates for the estimated mechanical angle phase of the motor depending on whether vibration suppression control is being performed. The power conversion device according to claim 1 .

3. the control device selects, as a true estimated mechanical angle phase, one of the n candidates for the estimated mechanical angle phase that is at 0° within a range in which a component of a single-times mechanical angular frequency of the estimated speed of the motor reaches 0 from a negative peak; The power conversion device according to claim 1 .

4. When the control device is performing vibration suppression control to suppress vibration of the motor by compensating for the output torque of the motor so that the output torque of the motor coincides with the load torque of the load element, the control device selects, as the true estimated mechanical angle phase, one of the n candidates for the estimated mechanical angle phase that has a value of 0° within a range in which the absolute value of the δ-axis current compensation value of the vibration suppression control ranges from 0 to a maximum value in a negative region. The power conversion device according to claim 1 .

5. the control device selects, as the true estimated mechanical angle phase, one of the n candidates for the estimated mechanical angle phase that is closest to 0° at a zero crossing timing at which the estimated output torque of the motor changes from positive to negative. The power conversion device according to claim 1 .

6. A motor drive device comprising the power conversion device according to any one of claims 1 to 5.

7. A refrigeration cycle device comprising the power conversion device according to any one of claims 1 to 5.

Images