JP2018148592A - Motor control device - Google Patents

Abstract

A motor control device capable of suppressing vibrations of a compressor is provided. Each of the compression mechanism sections 20 and 40 includes two compression mechanism sections whose displacement volumes are substantially equal to each other and whose rotation shafts 13 and 33 face each other along the axial direction, and the compression mechanism sections. A motor control device for a compressor in which two motors 10 and 30 to be driven are housed in a single sealed case 1a, wherein the motors are driven in reverse rotation to each other, and the rotational positions of the motors are different from each other by a predetermined difference. Control to be below the value. [Selection] Figure 1

Description

  Embodiments of the present invention relate to a motor control device for a compressor in which two compression mechanisms and two motors are accommodated in a single sealed case.

  A multi-cylinder type in which two compression mechanism units and two motors that drive these compression mechanism units are housed in a single sealed case, and the single operation of one compression mechanism unit and the simultaneous operation of both compression mechanism units can be selected. Compressors are known.

JP-A 61-268895

  In the above-described multi-cylinder compressor, each motor is operated independently, so that a large vibration is generated in the sealed case due to the relationship between the rotational position of one compression mechanism and the rotational position of the other compression mechanism. Sometimes.

  The objective of embodiment of this invention is providing the motor control apparatus which can suppress the vibration of a compressor.

  The motor control device according to claim 1 is a motor control device for a compressor in which two compression mechanism sections and two motors for driving the compression mechanism sections are housed in one sealed case, and the motors are connected to each other. Reverse rotation driving is performed, and the rotational positions of the motors are controlled so that the difference between them is equal to or less than a predetermined value.

The figure which shows the structure of the compressor and refrigeration cycle in connection with one Embodiment. The figure which shows the crank position of one compression mechanism part in the compressor of FIG. The figure which shows the crank position of the other compression mechanism part in the compressor of FIG. The block diagram which shows the control circuit of one Embodiment. The figure which shows the electric current, rotational speed, rotational mechanical angle, and vibration displacement of one motor in the compressor of FIG. The figure which shows rotating shaft torque T1, T2 in the compressor of FIG. 1, and correction | amendment torque component current Iqref1 'and Iqref2' in one Embodiment. The flowchart which shows starting control of the control circuit of one Embodiment. The figure which shows rotating shaft torque T1, T2 in case the difference (DELTA) Q of rotating machine angles Q1, Q2 in the compressor of FIG. 1 is 0 degree (or 180 degree), and its synthetic | combination rotating shaft torque T0. The figure which shows rotating shaft torque T1, T2 in case the difference (DELTA) Q of rotating machine angles Q1, Q2 in the compressor of FIG. 1 is 25 degrees, and its combined rotating shaft torque T0. The figure which shows rotating shaft torque T1, T2 in case the difference (DELTA) Q of rotating machine angles Q1, Q2 in the compressor of FIG. 1 is 90 degrees, and its synthetic rotating shaft torque T0. The figure which shows how the rotational shaft torque T1 of the compressor of FIG. 1 differs in the case of 2 cylinders, and the case of 1 cylinder.

Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 shows a configuration of a compressor and a refrigeration cycle mounted on an air conditioner or a heat source device.
The compressor 1 is covered with a horizontally long cylindrical sealed case 1a. A discharge pipe 2 is attached to the upper part of the sealed case 1a, and suction ports 3a, 3b, 3c, 3d are attached to the lower part. One end of a condenser (heat radiator) 51 is connected to the discharge pipe 2 via a high-pressure side pipe, and one end of an evaporator (heat absorber) 53 is connected to the other end of the condenser 51 via an expansion valve 52. Piping is connected. The other end of the evaporator 53 is pipe-connected to the suction ports 3a, 3b, 3c, 3d via a low-pressure side pipe. A bypass pipe 54 for reducing the load is connected between the high-pressure side pipe and the low-pressure side pipe, and an on-off valve 55 is disposed in the middle of the bypass pipe 54.

  In the sealed case 1a, a motor (brushless DC motor) 10 and a compression mechanism portion 20 are accommodated on one side of the mounting position of the discharge pipe 2, and a motor (brushless DC motor) 30 is compressed on the other side. The mechanism part 40 is accommodated. The compression mechanism units 20 and 40 are disposed in a state in which the respective excluded volumes are substantially equal to each other and the respective rotation shafts (rotation shafts 13 and 33) face each other along the axial direction.

  The motor 10 includes a cylindrical stator 11 disposed in contact with the inner peripheral surface of the sealed case 1a, a rotor 12 housed inside the stator 11, and a rotating shaft (shaft) that rotatably supports the rotor 12. 13, for example, a so-called four-pole motor in which four permanent magnets are embedded in the rotor 12, or a so-called six-pole motor in which six permanent magnets are embedded in the rotor 12. The rotation shaft 13 extends toward the compression mechanism unit 20 and passes through the center of the compression mechanism unit 20. , Two compression chambers (cylinders) 21a, 21b communicating with the suction ports 3a, 3b, cranks 14a, 14b mounted eccentrically on the rotary shaft 13 passing through the compression chambers 21a, 21b, and the cranks 14a, 14b The rollers 22a and 22b are mounted on the outer peripheral surface, and the gas refrigerant in the compression chambers 21a and 21b is compressed by the eccentric rotation of the rollers 22a and 22b and discharged into the sealed case 1a. The discharged gas refrigerant flows to the condenser 51 through the discharge pipe 2.

  The motor 30 includes a cylindrical stator 31 disposed in contact with the inner peripheral surface of the sealed case 1a, a rotor 32 housed inside the stator 31, and a rotating shaft (shaft) that rotatably supports the rotor 32. 33, for example, a so-called four-pole motor in which four permanent magnets are embedded in the rotor 32, or a so-called six-pole motor in which six permanent magnets are embedded in the rotor 12. The rotation shaft 33 extends toward the compression mechanism 40 and passes through the center of the compression mechanism 40. The compression mechanism section 40 includes two compression chambers (cylinders) 41a and 41b communicating with the suction ports 3a and 3b, cranks 34a and 34b mounted eccentrically on a rotary shaft 33 passing through the compression chambers 41a and 41b, and There are rollers 42a and 42b mounted on the outer peripheral surfaces of the cranks 34a and 34b, and the gas refrigerant in the compression chambers 41a and 41b is compressed by the eccentric rotation of the rollers 42a and 42b and discharged into the sealed case 1a. The discharged gas refrigerant flows to the condenser 51 through the discharge pipe 2. The compression mechanism unit 20 and the compression mechanism unit 40 are so-called two-cylinder rotary compressors each including two cylinders.

  FIG. 2 shows a state in which the rotary shaft 13 and the crank 14a (14b) in the compression mechanism unit 20 are viewed in the axial direction. FIG. 3 shows a state where the rotary shaft 33 and the crank 34a (34b) in the compression mechanism section 40 are viewed in the axial direction. ΔQ is the difference between the rotational mechanical angle Q1 that is the rotational position of the crank 14a in the compression mechanism section 20 and the rotational mechanical angle Q2 that is the rotational position of the crank 34a in the compression mechanism section 40. The rotating mechanical angles Q1 and Q2 of the cranks 14a and 34a correspond to the rotating mechanical angles of the rotors 12 and 32 in the motors 10 and 30, respectively.

A control circuit for the motors 10 and 30 is shown in FIG.
A converter 61 is connected to the AC power supply 60, and an inverter 62 is connected to the output terminal of the converter 61. Converter 61 converts the voltage of AC power supply 60 into a DC voltage. Inverter 62 converts the output voltage of converter 61 into a three-phase AC voltage having a predetermined frequency by switching. The motor 10 is operated by the output voltage of the inverter 62. Current sensors 63r, 63s, and 63t that detect currents flowing through the respective phase windings of the motor 10 are arranged on the energization line between the inverter 62 and the motor 10. A converter 64 is connected to AC power supply 60, and an inverter 65 is connected to the output terminal of converter 64. Converter 64 converts the voltage of AC power supply 60 into a DC voltage. Inverter 65 converts the output voltage of converter 64 into a three-phase AC voltage having a predetermined frequency by switching. The motor 30 is operated by the output voltage of the inverter 65. Current sensors 66 r, 66 s, 66 t that detect currents flowing through the phase windings of the motor 30 are arranged on the energization line between the inverter 65 and the motor 30.

Control unit 70 includes sensorless vector control units 71 and 72, and controls switching of inverters 62 and 65 in accordance with a command from main control unit 100. The main control unit 100 controls the inverters 62 and 65 through the control unit 70, and has the following means (1) to (2) as main functions.
(1) First control means for setting the number of operating motors 10 and 30 and the target rotational speed ωref in the compressor 1 according to the air conditioning load of the refrigeration cycle (such as the difference between the room temperature and the set temperature).

  (2) During simultaneous operation of the motors 10 and 30, the rotational positions of the rotors 12 and 32 in the motors 10 and 30 are controlled so that the difference between them is less than or equal to a predetermined value while the motors 10 and 30 are driven in reverse rotation with each other. Second control means.

  Specifically, the second control means detects the rotational electrical angles θest1 and θest2 of the rotors 12 and 32 in the motors 10 and 30 while driving the motors 10 and 30 in reverse rotation with each other, and the rotational electrical angles θest1. , Θest2 are converted into rotating mechanical angles Q1 and Q2, and the switching of the inverters 62 and 65 is controlled so that the difference ΔQ between the rotating mechanical angles Q1 and Q2 becomes a predetermined value or less. Further, the second control means superimposes a high frequency voltage on the output voltage of the inverters 62 and 65 when the motors 10 and 30 are started up, and detects a high frequency current flowing through the motors 10 and 30 by the superposition of the high frequency voltage. The motors 10 and 30 are started by detecting the rotational electrical angles θest1 and θest2 of the rotors 12 and 32 in the motors 10 and 30 from the current and controlling the switching of the inverters 62 and 65 in accordance with the rotational electrical angles θest1 and θest2. .

  The sensorless vector control unit 71 controls the switching of the inverter 62, and includes a current detection unit 81, a speed estimation calculation unit 82, an integration unit 83, a conversion unit 84, a subtraction unit 85, a speed control unit 86, a calculation unit 87, Subtractors 88, 89, 90, current controllers 91, 92, adders 93, 94, PWM signal generator 95, high frequency superimposition controller 96, speed fluctuation detector 97, and Iq corrector 98 are provided.

  The current detection unit 81 detects a current flowing through the motor 10 (referred to as a motor current) via current sensors 63r, 63s, and 63t, and based on the detected current, a field axis (d-axis) on the rotor shaft in the motor 10. A field component current (also referred to as a d-axis current) Id1 and a torque component current (also referred to as a q-axis current) Iq1 converted into coordinates and torque axis (q-axis) coordinates are detected. In addition, the current detection unit 81 detects a high-frequency current that flows through each phase winding of the motor 10 when the high-frequency superimposition control unit 96 superimposes the high-frequency voltage Vh1.

  When the high frequency superimposition controller 96 superimposes the high frequency voltage Vh1, the speed estimation calculation unit 82 obtains an evaluation index HYO of the high frequency superimposition method related to superposition of the high frequency voltage Vh1 based on the high frequency current detected by the current detector 81. The rotational speed ωest1 of the motor 10 is estimated by performing a proportional / integral (PI) control calculation on the evaluation index HYO. The speed estimation calculation unit 82 calculates the rotational speed of the motor 10 by calculation using the field component current Id1 and the torque component current Iq1 in the normal motor current detected by the current detection unit 81 when the high-frequency voltage Vh1 is not superimposed. Estimate ωest1.

  The integrator 83 integrates the estimated rotational speed ωest1 of the speed estimation calculator 82 to detect the rotational electrical angle θest1 that is the rotational position of the rotor 12 in the motor 10. The converting unit 84 converts the rotating electrical angle θest1 into the rotating mechanical angle Q1 based on the comparison between the pulsation pattern of the corrected target value Iqref1 ′ supplied from the subtracting unit 89 and the rotating electrical angle θest1. The rotational mechanical angle Q1 is supplied to the current detection unit 81, the PWM signal generation unit 95, and the main control unit 100. The subtracting unit 85 obtains a speed deviation between the target rotational speed ωref and the estimated rotational speed ωest1 by subtracting the estimated rotational speed ωest1 from the target rotational speed ωref set by the main control unit 100.

  The speed control unit 86 calculates a target value Iqref1 of the torque component current Iq1 by calculating a proportional / integral control (PI control) on the speed deviation obtained by the subtracting unit 85. The calculation unit 87 obtains the target value Idref1 of the field component current Id1 from the target value Iqref1 of the torque component current Iq1. The subtracting unit 88 obtains a deviation ΔId1 between the target value Idref1 and the field component current Id1 by subtracting the field component current Id1 from the target value Idref1. The subtraction unit 89 subtracts the torque component current correction value Iqx1 supplied from the Iq correction unit 98 from the target value Iqref1 of the torque component current Iq1, thereby obtaining a correction target value Iqref1 ′. The subtraction unit 90 subtracts the torque component current Iq1 from the correction target value Iqref1 ′ to obtain a deviation ΔIq1 between the correction target value Iqref1 ′ and the torque component current Iq1.

  The current control unit 91 obtains the field component voltage Vd1 converted into the d-axis coordinate on the rotor shaft in the motor 10 by proportional / integral control (PI control) calculation of the deviation ΔId1. The current control unit 92 obtains a torque component voltage Vq1 converted into q-axis coordinates on the rotor shaft in the motor 10 by proportional / integral control (PI control) calculation of the deviation ΔIq1. The adding unit 93 adds the field component Vdh1 of the high-frequency voltage Vh1 supplied from the high-frequency superimposing control unit 96 to the field component voltage Vd1. The adding unit 94 adds the torque component Vqh1 of the high-frequency voltage Vh1 supplied from the high-frequency superimposing control unit 96 to the torque component voltage Vq1.

  The PWM signal generation unit 95 generates a switching pulse width modulation signal (referred to as a PWM signal) for the inverter 62 according to the field component voltage Vd1, the torque component voltage Vq1, and the rotating machine angle Q1. By this PWM signal, each switching element of the inverter 62 is turned on / off, and drive voltages Vu, Vv, Vw for each phase winding of the motor 10 are output from the inverter 62.

  The high-frequency superimposing control unit 96 generates a field component (d-axis component) Vdh1 and a torque component (q-axis component) Vqh1 of the high-frequency voltage Vh1 to be superimposed on the drive voltages Vu, Vv, Vw from the inverter 62 to the motor 10. To do. Specifically, a carrier signal used for generating a PWM signal for switching the inverter 62 is taken from the PWM signal generation unit 95, and the interrupt processing is performed according to the cycle of the fetched carrier signal, so that the interrupt processing execution interval is set. A high frequency voltage Vh1 (field component Vdh1 and torque component Vqh1) having a corresponding period is generated. The field component Vdh1 is supplied to the adder 93, and the torque component Vqh1 is supplied to the adder 94.

  The speed fluctuation detection unit 97 detects a fluctuation in the estimated rotational speed ωest1 as a vibration component of the compression mechanism unit 20. An example of the fluctuation of the estimated rotational speed ωest1 is shown in FIG. 5 together with the motor currents Iu, Iv, Iw, the rotating machine angle Q1 of the rotor 12, and the vibration displacement of the rotating shaft 13. The vibration displacement of the rotating shaft 13 appears as the fluctuation of the estimated rotational speed ωest1. The Iq correction unit 98 obtains a torque component current correction value Iqx1 for minimizing “the fluctuation of the estimated rotational speed ωest1” detected by the speed fluctuation detection unit 97. The torque component current correction value Iqx1 is supplied to the subtraction unit 89. The subtracting unit 89 obtains a corrected target value Iqref1 ′ by subtracting the torque component current correction value Iqx1 from the target value Iqref1 of the torque component current Iq1. The corrected target value Iqref1 ′ pulsates as shown in FIG. 6, and the pulsation is synchronized with the pulsation of the rotation shaft torque T1 of the rotation shaft 13.

  In this way, by performing feedback correction on the target value Iqref1 of the torque component current Iq1 so that the fluctuation of the estimated rotational speed ωest1 is minimized, the pulsation of the corrected target value Iqref1 ′ and the pulsation of the rotational shaft torque T1 of the rotational shaft 13 Can be synchronized. By this synchronization, the conversion process (calculation) from the rotating electrical angle θest1 to the rotating mechanical angle Q1 in the converting unit 84 is accurately performed without being affected by the number of poles (four poles or six poles) of the motor 10. Can do.

  When the motor 10 is a four-pole motor, for example, as shown in FIG. 6, two cycles of the rotating electrical angle θest1 = 360 ° correspond to the rotating mechanical angle Q1 = 360 ° (one rotation), and the correction target value Iqref1 ′ is It pulsates in the same pattern every period of the rotating electrical angle θest1. Based on the relationship between the pulsation pattern of the corrected target value Iqref1 ′ and the period of the rotating electrical angle θest1, the rotating mechanical angle Q1 of the rotor 12 in the motor 10 can be accurately captured.

  When the motor 10 is, for example, a six-pole motor, as shown in FIG. 6, three periods of the rotating electrical angle θest1 = 360 ° correspond to the rotating mechanical angle Q1 = 360 ° (one rotation), and the corrected target value Iqref1 ′ is It pulsates with a different pattern for each cycle of the rotating electrical angle θest1. The rotational mechanical angle Q1 of the rotor 12 in the motor 10 can be accurately captured based on the relationship between the pulsation pattern of the correction target value Iqref1 ′ that differs for each period and the period of the rotating electrical angle θest1.

  On the other hand, the sensorless vector control unit 72 that controls the switching of the inverter 65 is, like the sensorless vector control unit 71, a current detection unit 81, a speed estimation calculation unit 82, an integration unit 83, a conversion unit 84, a subtraction unit 85, Speed control unit 86, calculation unit 87, subtraction units 88, 89, 90, current control units 91, 92, addition units 93, 94, PWM signal generation unit 95, high frequency superposition control unit 96, speed fluctuation detection unit 97, Iq correction Part 98 is provided.

  The sensorless vector control unit 72 is different from the sensorless vector control unit 71 in that the field component current Id2, the torque component current Iq2, the estimated rotational speed ωest2, the rotating electrical angle θest2, the rotating mechanical angle Q2, the target value Idref2, and the target value Iqref2, deviation ΔId2, torque component current correction value Iqx2, correction target value Iqref2 ′, deviation ΔIq2, field component voltage Vd2, torque component voltage Vq2, high frequency voltage Vh2 (field component Vdh2 and torque component Vqh2), etc. as control elements It is a point to handle.

  In particular, the speed fluctuation detection unit 97 of the sensorless vector control unit 72 detects the fluctuation of the estimated rotational speed ωest2 as the vibration component of the compression mechanism unit 40. The Iq correction unit 98 of the sensorless vector control unit 72 obtains a torque component current correction value Iqx2 for minimizing the “variation of the estimated rotational speed ωest2” detected by the speed variation detection unit 97. The torque component current correction value Iqx2 is supplied to the subtracting unit 89. The subtracting unit 89 obtains a corrected target value Iqref2 ′ by subtracting the torque component current correction value Iqx2 from the target value Iqref2 of the torque component current Iq2. The corrected target value Iqref2 ′ pulsates as shown in FIG. 6, and the pulsation is synchronized with the pulsation of the rotation shaft torque T2 of the rotation shaft 33.

  In this way, by performing feedback correction on the target value Iqref2 of the torque component current Iq2 so that the fluctuation of the estimated rotational speed ωest2 is minimized, the pulsation of the corrected target value Iqref2 ′ and the pulsation of the rotational shaft torque T2 of the rotational shaft 33 Can be synchronized. By this synchronization, the conversion process (calculation) from the rotating electrical angle θest2 to the rotating mechanical angle Q2 in the converting unit 84 is accurately performed without being affected by the number of poles (four poles or six poles) of the motor 30. Can do.

  As can be seen from FIG. 6, even if the motors 10 and 30 operate at the same rotational speed, the phase of the pulsation of the rotational shaft torque T1 in the motor 10 and the phase of the pulsation of the rotational shaft torque T2 in the motor 30 coincide. Is not limited. This phase difference corresponds to the difference ΔQ between the rotating mechanical angles Q1 and Q2. Further, this phase difference appears as vibration of the sealed case 1a.

  Therefore, the rotational electrical angle θest1 detected by the integration unit 83 of the sensorless vector control unit 71 is supplied to the subtraction unit 85 of the sensorless vector control unit 72. The subtracting unit 85 of the sensorless vector control unit 72 includes the rotating electrical angle θest1 from the sensorless vector control unit 71 and the rotating electrical angle θest2 detected by the integrating unit 83 of the sensorless vector control unit 72 (the rotational position of the rotor 32). ) To obtain the electrical angle deviation. The speed control unit 86 of the sensorless vector control unit 72 performs a proportional / integral control (PI control) operation on the electrical angle deviation obtained by the subtraction unit 85 of the sensorless vector control unit 72 to obtain a target of the torque component current Iq2. The value Iqref2 is obtained.

  Thus, by setting the target value Iqref2 of the torque component current Iq2 on the sensorless vector control unit 72 side based on the rotational electrical angle θest1 detected by the sensorless vector control unit 71, the rotational speeds of the motors 10, 30 are set. Are equal to each other, and the difference between the pulsation phase of the correction target value Iqref1 ′ on the sensorless vector control unit 71 side and the pulsation phase of the correction target value Iqref2 ′ on the sensorless vector control unit 72 side is 0 ° (or 180 °). °). As a result, the difference between the pulsation phase of the rotation shaft torque T1 in the motor 10 and the pulsation phase of the rotation shaft torque T2 in the motor 30 (difference ΔQ between the rotating mechanical angles Q1, Q2) becomes 0 ° (or 180 °). . Thereby, vibration of sealed case 1a can be prevented.

Next, control executed by the main control unit 100 through the control unit 70 will be described with reference to the flowchart of FIG.
When the motors 10 and 30 are activated (YES in step S1), the main control unit 100 executes so-called high-frequency superposition control by superimposing high-frequency voltages (step S2). That is, in the high frequency superimposition control, the main control unit 100 outputs drive voltages Vu, Vv, and Vw having predetermined frequencies from the inverters 62 and 65 and superimposes the high frequency voltage Vh on the drive voltages Vu, Vv, and Vw, and this superimposition. Is used to detect the high-frequency current flowing in the motors 10 and 30, and the rotational electrical angles θest1 and θest2 of the motors 10 and 30 are detected from the detected currents, and the switching of the inverters 62 and 63 is controlled according to the rotational electrical angles θest1 and θest2. Thus, the motors 10 and 30 are driven to rotate in opposite directions.

  Along with the high-frequency superposition control, the main control unit 100 determines the starting speed α as the target rotational speed ωref (step S3) and converts the detected rotating electrical angles θest1, θest2 into rotating mechanical angles Q1, Q2. Execute (step S4).

  When the motors 10 and 30 are started, the main control unit 100 reduces the difference between the high-pressure side pressure and the low-pressure side pressure by opening the open / close valve 55 of the refrigeration cycle in advance so that the compressor 1 does not vibrate greatly. The control which reduces the compression load of the compressor 1 is performed. However, if the compression load is too small, pulsation of the rotation shaft torques T1 and T2 will not occur. If the pulsation of the rotation shaft torques T1 and T2 does not occur, the conversion process to the rotary machine angles Q1 and Q2 will not be completed.

  Therefore, when the conversion process to the rotating machine angles Q1, Q2 is not completed (NO in step S5), the main control unit 100 reduces the starting speed α by a predetermined value Δα (step S6), It is determined whether or not the speed α has reached the allowable minimum value αmin (step S7). When the reduced startup speed α has not reached the allowable minimum value αmin (NO in step S7), the main control unit 100 returns to step S2 and continues the high-frequency superposition control, and the reduced startup speed α. Is determined as a new target rotational speed ωref (step S3). By reducing the starting speed α, pulsation of the rotational shaft torques T1 and T2 necessary for the conversion processing to the rotary machine angles Q1 and Q2 is generated.

  When the conversion process is not completed in spite of the reduction of the startup speed α (NO in step S5), the main control unit 100 reduces the startup speed α by the predetermined value Δα again (step S6), and the startup after the reduction is performed. It is determined whether or not the service speed α has reached the allowable minimum value αmin (step S7). When the reduced startup speed α has not reached the allowable minimum value αmin (NO in step S7), the main control unit 100 returns to step S2 and continues the high-frequency superposition control, and the reduced startup speed α. Is determined as a new target rotational speed ωref (step S3).

  When the starting speed α after the reduction reaches the allowable minimum value αmin (YES in step S7), the main control unit 100 closes the on-off valve 55 and increases the compression load (step S8). By increasing the compression load, it is possible to generate pulsations of the rotational shaft torques T1 and T2 necessary for the conversion processing to the rotary machine angles Q1 and Q2.

  After the increase in the compression load, the main control unit 100 returns to step S2 to continue the high-frequency superposition control, and sets the reduced startup speed α (= αmin) as a new target rotational speed ωref (step S3).

  When the conversion processing to the rotary machine angles Q1 and Q2 is completed (YES in step S5), the main control unit 100 controls the rotary machine angle Q1 obtained by the conversion unit 84 of the sensorless vector control unit 71 and the sensorless vector control. Synchronous control for maintaining the difference ΔQ (the phase difference between the pulsations of the rotating shaft torques T1 and T2) obtained by the converting unit 84 of the unit 72 at a predetermined value or less, for example, 0 ° (or 180 °). Execute (Step S9). The main control unit 100 continues this synchronous control even after activation.

  FIG. 8 shows the relationship between the rotational shaft torques T1 and T2 and the combined rotational shaft torque T0 when the synchronous control is executed while the motors 10 and 30 are rotationally driven in opposite directions. Since the pulsations of the rotation shaft torques T1 and T2 are synchronized with each other in a similar waveform that swings to the positive side and the negative side, the rotation shaft torques T1 and T2 cancel each other and the combined rotation shaft torque T0 becomes zero. Thereby, the vibration of the sealed case 1a can be suppressed. Since vibration can be suppressed, noise can be reduced, and so-called piping stress generated at the connecting portion between the compressor 1 and the refrigerant piping can be suppressed within a specified value.

  As for the synchronous control, the difference ΔQ (the phase difference between the pulsations of the rotating shaft torques T1, T2) between the rotating machine angles Q1, Q2 may be maintained at a predetermined value, for example, 25 ° or less. FIG. 9 shows the relationship between the rotational shaft torques T1 and T2 and the combined rotational shaft torque T0 when synchronous control is performed to keep the difference ΔQ between the rotational mechanical angles Q1 and Q2 at 25 °. Although fluctuation occurs in the combined rotational shaft torque T0, the vibration of the sealed case 1a can be suppressed to the level of vibration during the independent operation of either one of the motors 10 and 30. For reference, as shown in FIG. 10, in the synchronous control in which the difference ΔQ between the rotating machine angles Q1 and Q2 is maintained at 90 °, the combined rotating shaft torque T0 fluctuates greatly, resulting in a worst state in which large vibration is generated in the sealed case 1a. .

  In the above embodiment, the case where the compression mechanism sections 20 and 40 are each a two-cylinder type having two compression chambers has been described as an example. However, the compression mechanism sections 20 and 40 each have one compression chamber. In the case of a mold, it can be similarly implemented. FIG. 11 shows how the pulsation pattern of the rotational shaft torque T1 differs between the case of 2 cylinders and the case of 1 cylinder.

  The above embodiments and modifications are presented as examples, and are not intended to limit the scope of the invention. The novel embodiments and modifications can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In these embodiments and modifications, the scope of the invention is included in the gist, and is included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Compressor, 1a ... Sealing case, 10, 30 ... Motor, 11, 31 ... Stator, 12, 32 ... Rotor, 13, 33 ... Rotating shaft, 20, 40 ... Compression mechanism part, 21a, 21b ... Compression chamber, 14a, 14b ... crank, 22a, 22b ... roller, 41a, 41b ... compression chamber, 34a, 34b ... crank, 42a, 42b ... roller, 51 ... condenser, 52 ... expansion valve, 53 ... evaporator, 55 ... open / close valve , 60 ... AC power supply, 61, 64 ... converter, 62, 65 ... inverter, 70 ... control unit, 71, 72 ... sensorless vector control unit, 100 ... main control unit, 81 ... current detection unit, 82 ... speed estimation calculation 83: Integration unit 84: Conversion unit 86 ... Speed control unit 87 ... Calculation unit 91, 92 ... Current control unit 95 ... PWM signal generation unit 96 ... High frequency superposition control unit 97 ... Speed fluctuation detection , 98 ... Iq correction unit

Claims (4)

A compressor motor control device comprising two compression mechanism units and two motors for driving these compression mechanism units housed in a single sealed case,
The motor control device, wherein the motors are driven to rotate reversely to each other, and the rotational positions of the motors are controlled so that the difference between them is not more than a predetermined value. 2. The motor control device according to claim 1, wherein each of the compression mechanism sections has a mutually excluded volume that is substantially equal to each other, and the respective rotation shafts face each other along the axial direction. The motors are driven in reverse rotation with respect to each other, the rotational electrical angles of the motors are detected, the rotational electrical angles are converted into rotational mechanical angles, and the rotational mechanical angles are controlled so that the difference between them is below a predetermined value. The motor control device according to claim 1. A plurality of inverters for outputting drive voltages to the motors;
When starting up each motor, a high-frequency voltage is superimposed on the output voltage of each inverter, a high-frequency current flowing through each motor is detected by the superposition of the high-frequency voltage, and a rotational electrical angle of each motor is detected from the detected current. The motor control device according to claim 3, wherein the inverters are controlled in accordance with the detected rotational electrical angle.

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