JP6010071B2 - Motor control device and refrigeration / air-conditioning device - Google Patents

Description

  The present invention relates to a motor control device that controls a motor, and more particularly to a motor control device having an inverter circuit. The present invention also relates to a refrigeration apparatus and an air conditioner (collectively referred to as a refrigeration / air conditioning apparatus) equipped with a motor control device.

  In recent years, an inverter is used for variable speed control of a synchronous motor that drives a load element accompanied by load torque fluctuation. As a thing provided with the load element which has a periodic load torque fluctuation, a single rotor type compressor or a reciprocating type compressor is mentioned. Single rotor type compressors or reciprocating type compressors are widely used as compressors mounted on home appliances such as air conditioners and refrigerators.

  FIG. 1A is a diagram illustrating a load torque characteristic of a single rotor compressor, and FIG. 1B is a diagram illustrating a load torque characteristic of a reciprocating compressor. In a single rotor type compressor or a reciprocating type compressor, a compression cycle comprising a working medium suction step, a compression step, and a discharge step is performed once per rotation. Since the working medium is compressed immediately before the discharge, the load torque increases, and immediately after the discharge, the working medium is removed, so the load torque decreases. That is, the load torque varies depending on the mechanical position of the rotor.

  In a drive system that drives a synchronous motor without using a position sensor that detects the mechanical position of the rotor, the motor controller cannot determine the mechanical position of the rotor, so the torque required to rotate the synchronous motor is determined. Can not. For this reason, in a drive system in which a synchronous motor is driven without a position sensor, the motor drive voltage is set high to increase the motor torque so that the compressor can be driven even under a high working medium pressure. The compressor is running.

Japanese Patent No. 5385557

  However, as described above, since the load torque varies depending on the mechanical position of the rotor, the angular velocity of the rotor varies, and accordingly, the motor drive current varies.

  By the way, the motor control device is generally provided with an overcurrent protection circuit for protecting the element of the inverter and preventing the demagnetization of the magnet provided in the synchronous motor, and is set in the overcurrent protection circuit. When a current exceeding the overcurrent threshold flows, the driving of the motor is stopped. Therefore, when the fluctuation of the motor driving current is large, such as when the compressor is under a heavy load, the motor driving current may reach the above overcurrent threshold, and the compressor may stop.

  In the motor control device described in Patent Document 1, the torque control unit stores a torque correction amount corresponding to the mechanical position (mechanical angle) of the rotor of the synchronous motor. For example, an electrical angle such as a 4-pole synchronous motor is stored. If two rotations correspond to one mechanical angle, whether the current electrical angle is in the range of mechanical angle 0 degrees to mechanical angle 180 degrees, or in the range of mechanical angle 180 degrees to mechanical angle 360 degrees, As long as this determination is made, the mechanical position of the rotor of the synchronous motor can be determined, and appropriate torque correction can be performed.

  However, the motor control apparatus may not have torque correction data corresponding to the mechanical position (mechanical angle) of the rotor of the synchronous motor. For example, a case where the rotor of the synchronous motor and the rotor of the load element such as a compressor are not directly connected, or a case where the rotor of the synchronous motor and the rotor of the load element are coupled without performing angular alignment are conceivable. In this case, even if the mechanical angle of the synchronous motor is determined, the mechanical position of the rotor of the load element is not yet known, and appropriate torque correction cannot be performed.

  In view of the above situation, the present invention provides a motor control device that prevents an overcurrent of a motor drive current even when the angle difference between the mechanical angle of the rotor of the motor and the mechanical angle of the rotor of the load element is arbitrary. An object of the present invention is to provide a refrigeration / air-conditioning apparatus equipped with the motor control device.

  In order to achieve the above object, a motor control device according to the present invention is a device for controlling a motor that drives a load element having a periodic load torque fluctuation, and detects an amplitude of a current that drives the motor. A detection unit; and a correction unit that corrects a motor drive voltage for driving the motor. The correction unit is detected by the detection unit from a full electrical angle range of the motor corresponding to one cycle of the load element. The first electrical angle at which the motor drive current reaches the maximum peak is estimated, and the entire electrical angle range is divided into one electrical angle range including the first electrical angle and the other electrical range excluding the one electrical angle range. The first electric angle range is divided into an electric angle range, and the first correction for reducing the motor driving voltage is performed in the one electric angle range (first configuration).

  In the motor control device having the first configuration, the one electrical angle range includes an electrical angle at which the motor driving current is adjacent to at least one immediately before and immediately after the first electrical angle (second configuration). It is good also as a structure.

  In the motor control device having the first or second configuration, the correction unit corrects the motor drive voltage based on the motor drive current while the motor is accelerated after starting (third configuration). It is good.

  The motor control device having any one of the first to third configurations includes a voltage correction pattern storage unit that stores a voltage correction pattern corresponding to one cycle of the load element, and the correction unit is configured to store the voltage correction pattern. A fluctuation amount of the motor driving current when the motor is driven by the motor driving voltage corrected by the voltage correction pattern which gives a correction coefficient for shifting the phase by a predetermined angle is expressed by two or more correction coefficients. Based on a comparison result with respect to a set value, a second correction for determining the correction coefficient is performed, the second correction is performed after the first correction is canceled, and the voltage in the second correction is A configuration (fourth configuration) in which the set value of the correction coefficient is determined so that the maximum correction portion of the correction pattern does not fall within the one electrical angle range divided by the first correction.

  In the motor control device of the fourth configuration, the correction coefficient includes a gain of the voltage correction pattern, and a result obtained by comparing a fluctuation amount of the motor drive current when the motor is driven with the gain set to a different value. As an index, the gain may be determined (fifth configuration).

  In the motor control device having the fourth or fifth configuration, the shape of the voltage correction pattern is obtained by subtracting a load torque value for each angle of the load element from an average value of the load torque for the one cycle of the load element. It is good also as a structure (6th structure) which is a shape based on the function which integrated the value with the angle of the said load element.

  In the motor control device having any one of the fourth to sixth configurations, the shape of the voltage correction pattern is a measurement of an angular velocity change for one cycle of load torque fluctuation when the load element is rotated at a constant torque. However, a configuration based on the variation pattern (seventh configuration) may be employed.

  In the motor control device having the sixth or seventh configuration, the voltage correction pattern has a configuration in which the correction amount is smaller than that of the function or the variation pattern as a basis (eighth configuration). It is good.

  A refrigeration / air-conditioning apparatus according to the present invention includes the motor control device having any one of the first to eighth configurations, a synchronous motor driven by the motor control device, and a compressor driven by the synchronous motor. The configuration (the ninth configuration) is assumed.

  According to the present invention, even when the correspondence between the mechanical angle of the rotor of the load element and the mechanical angle of the motor is unknown, it is possible to prevent overcurrent of the motor drive current and to suppress the fluctuation amount of the motor drive current. It is possible to realize a refrigeration / air conditioning apparatus equipped with a control device and the motor control device.

It is a figure which shows the load torque characteristic of a single rotor type compressor. It is a figure which shows the load torque characteristic of a reciprocating compressor. It is a figure showing a schematic structure of a motor control device concerning a 1st embodiment of the present invention. It is a flowchart which shows operation | movement of the motor drive voltage waveform correction | amendment part in 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the motor drive voltage waveform correction | amendment part in 2nd Embodiment of this invention. It is a motor drive current waveform figure for demonstrating the correction range in 3rd Embodiment of this invention. It is a figure which shows an example of the motor drive voltage waveform after performing the correction | amendment using a voltage correction pattern. It is a motor drive current waveform figure for demonstrating the correction range in the modification of 3rd Embodiment of this invention. It is a motor drive current waveform figure for demonstrating the correction range in the other modification of 3rd Embodiment of this invention. It is a figure which shows schematic structure of the motor control apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows an example of a voltage correction pattern. It is a flowchart which shows operation | movement of the motor drive voltage waveform correction | amendment part in 4th Embodiment of this invention. It is a flowchart which shows operation | movement of the motor drive voltage waveform correction | amendment part in 4th Embodiment of this invention. It is a figure which shows the some example of the motor drive current waveform of each phase. It is a figure which shows an example of the relationship between the pulsation amount of a motor drive current, and the phase shift amount of a voltage correction pattern. It is a figure which shows an example of the relationship between the pulsation amount of a motor drive current, and the correction gain of a voltage correction pattern. It is a flowchart which shows operation | movement of the motor drive voltage waveform correction | amendment part in 5th Embodiment of this invention. It is a flowchart which shows operation | movement of the motor drive voltage waveform correction | amendment part in 5th Embodiment of this invention. It is a figure which shows an example of the voltage correction pattern in 8th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 2 shows a schematic configuration of the motor control device according to the first embodiment of the present invention. The motor control device according to the present embodiment includes a converter circuit 2, an inverter circuit 3, a current detection resistor (shunt resistor) R1, a current detection circuit 5, and a microcomputer M1. An AC power source 1 is connected to the input side of the converter circuit 2, and a synchronous motor 4 is connected to the output side of the inverter circuit 3. The synchronous motor 4 drives a load element that accompanies periodic load torque fluctuations.

  The converter circuit 2 converts the AC voltage from the AC power source 1 into a DC voltage and supplies it to the inverter circuit 3. The inverter circuit 3 converts the DC voltage from the converter circuit 2 into a three-phase AC voltage and supplies it to the synchronous motor 4. The output side of the converter circuit 2 and the input side of the inverter circuit 3 are connected by a positive DC line and a negative DC line, and a current detection resistor R1 is provided on the negative DC line. The current detection circuit 5 detects the current flowing through the inverter circuit 3 based on the voltage generated at both ends of the current detection resistor R1, amplifies the detected current, and outputs the amplified current signal to the microcomputer M1. That is, the current detection circuit 5 functions as a current detection unit that detects a current flowing through the inverter circuit 3.

  The microcomputer M1 is a circuit for driving and controlling the synchronous motor 4, and includes a motor drive current estimation unit 6, a motor drive current storage unit 7, a rotation speed setting unit 8, a motor drive voltage waveform creation unit 9, The motor drive voltage waveform correction unit 10 and the PWM waveform creation unit 11 are included, and the processing described below is performed according to a program.

  The motor drive current estimation unit 6 includes a current change calculation unit (not shown) and a distribution calculation unit (not shown). The current change calculation unit calculates a current change from the input current signal, and the current signal The motor drive current is estimated and calculated by the distribution calculation means from the amount of change. Here, as the current change calculation means and the distribution calculation means, for example, those described in JP-A-8-19263 can be used. When the one described in Japanese Patent Laid-Open No. 8-19263 is used, the current change calculation means is a DC current signal (output signal of the current detection circuit 5) immediately before and after switching of each phase driving element of the inverter circuit 3. The distribution calculation means distributes the change of the current signal (output signal of the current detection circuit 5) for each phase according to the switching timing of each phase drive element of the inverter circuit 3, and determines the change by phase. The motor drive current is estimated and calculated. By providing the motor drive current estimation unit 6, the motor drive current can be estimated and calculated without using a current sensor for detecting the motor drive current, such as a current sensor composed of a coil and a Hall element, or a current transformer. Therefore, cost can be reduced.

  The motor drive current storage unit 7 stores at least one phase current amplitude value and an electrical angle for at least one load torque fluctuation in the load element from the phase-specific motor drive currents estimated and calculated by the motor drive current estimation unit 6. To do.

  The rotation speed setting unit 8 determines a forced excitation angular frequency corresponding to the target rotation speed command value, and outputs the determined forced excitation angular frequency to the motor drive voltage waveform creation unit 9. The target rotational speed command value is mounted on, for example, a device including the motor control device according to the present embodiment, the synchronous motor 4, and a load element with periodic load torque fluctuations driven by the synchronous motor 4. Then, it is transmitted from the control unit that controls the entire device to the rotation speed setting unit 8.

  The motor drive voltage waveform creation unit 9 stores in advance a sine wave data table composed of a predetermined number of data, and corresponds to each phase of the motor winding terminal of the synchronous motor 4 based on the forced excitation angular frequency. Motor drive basic voltage waveform data (in the case of three phases, sine wave data shifted by 120 degrees in electrical angle) is read from the sine wave data table and output to the motor drive voltage waveform correction unit 10. In the present embodiment, the motor drive basic voltage waveform is created using the sine wave data table. However, the present invention is not limited to this, and may be other than a sine wave, for example. The motor drive basic voltage waveform may be created by

  The motor drive voltage waveform correction unit 10 corrects the motor drive basic voltage waveform based on the motor drive current. Detailed operation of the motor drive voltage waveform correction unit 10 will be described later.

The PWM waveform creation unit 11 converts the corrected phase motor drive voltage waveform data output from the motor drive voltage waveform correction unit 10 into each phase PWM waveform signal, and converts the converted phase PWM waveform signal into the inverter circuit 3. Corresponding drive elements (U-phase upper drive element Q _U , U-phase lower drive element Q _x , V-phase upper drive element Q _V , V-phase lower drive element Q _y , W-phase upper drive element Q _W , W To the lower phase driving element Q _z ). For example, the PWM waveform creation unit 11 generates a triangular wave with a PWM carrier cycle, compares the triangular wave with each phase motor drive voltage waveform after correction, and outputs High / Low based on the comparison result. Phase PWM waveform signal is output. The inverter circuit 3 converts the DC voltage from the converter circuit 2 into a motor drive waveform of each phase based on the PWM waveform signal of each phase, and converts the motor drive waveform of each phase to the motor winding of each phase of the synchronous motor 4. Apply to the wire. Thereby, the rotor of the synchronous motor 4 rotates.

  Next, the detailed operation of the motor drive voltage waveform correction unit 10 will be described. Here, a case where the synchronous motor 4 is a three-phase six-pole motor will be described. Further, it is assumed that one cycle of load torque fluctuation in the load element is one rotation of the synchronous motor 4. The motor drive voltage waveform correction unit 10 starts the flow operation shown in FIG. 3 when starting the synchronous motor 4. When the activation of the synchronous motor 4 is started, the load element is also started, and the load element is accelerated at a predetermined acceleration to a stable rotation speed (for example, 1600 rpm) which is a motor rotation speed necessary for stably completing the start-up. The

  First, the motor drive voltage waveform correction unit 10 starts acceleration at a predetermined acceleration (step # 10).

  Note that the motor control device according to the present embodiment performs a phase fixing operation in which the initial position of the rotor is set to the designated electrical angle by applying a voltage at which the designated electrical angle is excited to the synchronous motor 4 before starting the acceleration. Next, the electrical angle is sequentially updated at a predetermined speed to accelerate to the feedback start rotational speed while maintaining the rotation of the rotor (initial acceleration). Since the motor drive current is still small at the initial acceleration stage and it is difficult to detect the rotor position, it is difficult to feed back the actual rotation state of the rotor to the rotation speed setting unit 8 or the like. Therefore, in the initial acceleration, the rotor is accelerated at the update speed of the electrical angle without performing the rotation speed correction by feedback, and the fluctuation of the rotation speed becomes relatively large.

  When the acceleration is accelerated to the feedback start rotational speed, the actual rotational state of the synchronous motor 4 can be grasped. Therefore, the drive control (the rotational speed) can correct the deviation between the actual rotational speed of the synchronous motor 4 and the command rotational speed by the rotational speed feedback. (Feedback drive control) is possible, and acceleration with little fluctuation in the rotational speed can be performed.

  Therefore, since the motor drive current is small during initial acceleration as described above, and the deviation between the motor drive command signal and the actual rotor operation is large, it is difficult to accurately determine the amplitude and electrical angle at which the motor drive current peaks. Therefore, in the motor control device according to the present embodiment, the processing of step # 20 is executed, and the pulsation detection of the motor drive current is started after switching from the initial acceleration to the acceleration by the rotational speed feedback drive control.

  In step # 20, the motor drive voltage waveform correction unit 10 determines whether or not the rotational speed of the synchronous motor 4 is equal to or higher than the pulsation detection start rotational speed. If the rotation speed of the synchronous motor 4 is not equal to or higher than the pulsation detection start rotation speed (NO in step # 20), the determination is continued. If the rotation speed of the synchronous motor 4 is equal to or higher than the pulsation detection start rotation speed (YES in step # 20), the process proceeds to step # 30.

  The pulsation detection start rotational speed can be set to a rotational speed higher than the rotational speed at which the drive control of the synchronous motor 4 shifts to the rotational speed feedback drive control. Further, instead of the determination based on the pulsation detection start rotation speed, it may be determined that the drive control of the synchronous motor 4 has shifted to the rotation speed feedback drive control. As a result, the amplitude and electrical angle at which the motor drive current reaches a peak can be accurately detected, and furthermore, the motor drive current in the drive control of the synchronous motor 4 that is the same as that at the completion of startup or normal operation is detected. The determination of the corrected electrical angle range described later can be used as it is. It should be noted that immediately after the shift to the rotational speed feedback drive control, the correction control by the rotational speed feedback may not yet converge and the rotation may not be stable. After the shift to the control, it is preferable that the correction control by the rotation speed feedback converges and the rotation is stabilized, for example, after at least one rotation of the rotor.

  Further, the determination of the corrected electrical angle range and the setting of the correction after step # 30 are preferably completed while the rotational speed of the synchronous motor 4 is as low as possible. For example, when the load element is a compressor, the compressor It is preferable that the rotation is completed by a rotation speed lower than the minimum rotation speed for maintaining the performance. The synchronous motor generally increases the drive voltage as the rotational speed increases. When the rotational speed increases, the risk that the motor drive current exceeds the overcurrent threshold set in the overcurrent protection circuit increases. Furthermore, at a rotational speed that is equal to or higher than the minimum rotational speed set for the compressor, there is a risk that periodic load torque fluctuations increase in order to achieve performance as a compressor, and the rotational speed is lower than the minimum rotational speed. It is preferable that correction is performed so as to reduce the motor driving voltage in the electrical angle range including the electrical angle at which the current amplitude becomes the maximum value by determining the corrected electrical angle range.

  In Step # 30, the motor drive voltage waveform correction unit 10 determines the current amplitude on the upper side of the U phase (the maximum value of the motor drive current in a section where a positive voltage is applied to the U phase) and the lower side of the U phase for each electrical cycle. Current amplitude (the maximum value of the motor drive current in a section where a negative voltage is applied to the U phase) is detected and stored together with the electrical angle.

  Thereafter, the motor drive voltage waveform correction unit 10 determines whether or not the rotor of the synchronous motor 4 has made one rotation from the detection start in step # 30, in other words, three electrical angles have elapsed from the detection start in step # 30. (Step # 40). If the rotor of the synchronous motor 4 has not made one rotation since the detection start in step # 30 (NO in step # 40), the determination is continued. If the rotor of the synchronous motor 4 has made one rotation since the detection start in step # 30 (YES in step # 40), the process proceeds to step # 50.

  In step # 50, the motor drive voltage waveform correction unit 10 extracts the current amplitude that takes the maximum value from the current amplitudes that are detected and stored, and calculates the current amplitude that takes the maximum value and the other current amplitudes. It is determined whether the difference is greater than or equal to a threshold value. For example, when the current amplitude on the U phase lower side in the second cycle is the maximum current amplitude, the current amplitude on the lower U phase in the second cycle and the current amplitude on the lower U phase in the first cycle are It is determined whether or not the difference between the current amplitude on the lower U-phase in the second cycle and the current amplitude on the lower U-phase in the third cycle is greater than or equal to the threshold.

  If the difference between the maximum current amplitude and the other current amplitude is less than the threshold (NO in step # 50), the motor drive voltage waveform correction unit 10 has reached the stable rotational speed of the synchronous motor 4 (Step # 60). If the rotational speed of the synchronous motor 4 has not reached the stable rotational speed (NO in step # 60), the process returns to step # 30. On the other hand, if the rotational speed of the synchronous motor 4 has reached the stable rotational speed (YES in step # 60), since the pulsation of the motor drive current is small from the beginning until the stable rotational speed is reached from the pulsation detection start rotational speed, it will be described later. The activation of the synchronous motor 4 is completed without executing the process of step # 70. When the activation of the synchronous motor 4 is completed, the activation of the load element is also completed. The synchronous motor 4 and the load element shift to normal operation after completion of startup.

  If the difference between the maximum current amplitude and the other current amplitude is greater than or equal to the threshold (YES in step # 50), the process proceeds to step # 70.

  In step # 70, the motor drive voltage waveform correction unit 10 corrects the voltage command value according to the electrical angle at which the current amplitude becomes the maximum value, and corrects the motor drive basic voltage waveform with the corrected voltage command value. As a specific example, the voltage command value is corrected to be decreased by a predetermined amount (for example, 10%) in the range of the electrical angle of 120 degrees centered on the electrical angle at which the maximum current amplitude is detected, and the remaining electrical angle of 960 degrees. The voltage command value is not corrected within the range. As a result, the motor drive voltage is reduced by a predetermined amount (for example, 10%) in the range of the electrical angle of 120 degrees centered on the electrical angle at which the current amplitude having the maximum value is detected, compared to the range of the remaining electrical angle of 960 degrees. . The reason why correction is performed in the range of electrical angle 120 degrees centered on the electrical angle at which the current amplitude at which the maximum value is obtained is detected is because the first 30 degrees in the range of electrical angle 180 degrees corresponding to a half wave of a sine wave. This is because the current value is less than half of the current amplitude in each of the last 30 degrees, and therefore it is very unlikely that the current amplitude will be larger than the corrected current amplitude without correction.

  By this correction, the motor drive voltage at the electrical angle at which the current amplitude becomes the maximum value is reduced by a predetermined amount, so that the current amplitude at the electrical angle can be reduced. That is, the phase (electrical angle) at which the current amplitude protrudes is detected with respect to the periodic fluctuation of the current amplitude caused by the load element having the periodic load torque fluctuation, and the current in the phase region (electrical angle range) is detected. The motor drive voltage is decreased so as to decrease. Therefore, the maximum value of the motor drive current can be suppressed and the motor drive current can be prevented from becoming an overcurrent.

  When the motor drive voltage is decreased, the motor torque is reduced, and the acceleration of the motor is slowed down. However, the electrical angle range other than the electrical angle range for reducing the motor drive voltage (in the above example, the remaining electrical angle of 960 degrees) In the range), since the motor drive voltage is not reduced, the motor torque is hardly reduced. Therefore, it is possible to suppress the motor drive current from becoming an overcurrent without greatly impairing the set acceleration rate, and the synchronous motor 4 and the load element can be completed quickly and reliably.

  In step # 80 following step # 70, the motor drive voltage waveform correction unit 10 determines whether or not the rotational speed of the synchronous motor 4 has reached a stable rotational speed (step # 80). If the rotation speed of the synchronous motor 4 has not reached the stable rotation speed (NO in step # 80), the correction in step # 70 is maintained and the acceleration is continued. If the rotation speed of the synchronous motor 4 has reached the stable rotation speed (YES in step # 80), the activation of the synchronous motor 4 is completed. When the activation of the synchronous motor 4 is completed, the activation of the load element is also completed. The synchronous motor 4 and the load element shift to normal operation after completion of startup.

  As a modification of the present embodiment, instead of step # 50, it is determined whether or not the difference between the current amplitude having the maximum value and the second largest current amplitude of the other electrical angular period corresponding thereto is equal to or greater than the threshold value. The step of determining whether the difference between the current amplitude taking the maximum value and the current amplitude taking the minimum value of the other electrical angle period corresponding to the maximum value is greater than or equal to a threshold value, the current amplitude taking the maximum value being greater than or equal to the threshold value Any one of the steps of determining whether or not is may be adopted.

Second Embodiment
The schematic configuration of the motor control device according to the second embodiment of the present invention is the same as the schematic configuration of the motor control device according to the first embodiment of the present invention.

  In the present embodiment, the motor drive voltage waveform correction unit 10 performs the operation of the flowchart shown in FIG. The flowchart shown in FIG. 4 is obtained by adding steps # 51 to # 55 to the flowchart shown in FIG. When the motor drive voltage waveform correction unit 10 performs the operation of the flowchart shown in FIG. 4, the motor control device according to the present embodiment has the same effects as the motor control device according to the first embodiment of the present invention. Furthermore, it is possible to prevent the correction process in step # 70 from being erroneously executed due to the influence of noise or the like.

  Hereinafter, differences from the first embodiment of the present invention will be described, and description of points of coincidence with the first embodiment of the present invention will be omitted.

  If it is determined in step # 50 that the difference between the maximum current amplitude and the other current amplitude is greater than or equal to the threshold (YES in step # 50), the motor drive voltage waveform correction unit 10 performs the first rotation of the rotor. It is determined whether or not the maximum current amplitude electrical angle is already stored (step # 51).

  If the maximum current amplitude electrical angle for the first rotation of the rotor has not yet been stored (NO in step # 51), the motor drive voltage waveform correction unit 10 determines the electrical angle at which the current amplitude has reached the maximum value for the first rotation of the rotor. The maximum current amplitude electrical angle is stored (step # 52), and the process proceeds to step # 60.

  On the other hand, if the maximum current amplitude electrical angle of the first rotation of the rotor is already stored (YES in step # 51), the motor drive voltage waveform correction unit 10 rotates the electrical angle at which the current amplitude becomes the maximum value by rotating the rotor two times. The maximum current amplitude electrical angle of the eye is stored (step # 53), and the process proceeds to step # 54.

  In step # 54, the motor drive voltage waveform correcting unit 10 determines that the maximum current amplitude electrical angle at the first rotation of the rotor and the maximum current amplitude electrical angle at the second rotation of the rotor are the same or substantially the same (for example, a range of ± α degrees: α Is an electrical angle of any positive number).

  If the maximum current amplitude electrical angle of the first rotation of the rotor and the maximum current amplitude electrical angle of the second rotation of the rotor are not the same or substantially the same (NO in step # 54), the motor drive voltage waveform correction unit 10 The maximum current amplitude electrical angle of the second rotation of the rotor is stored as a new maximum current amplitude electrical angle of the first rotation of the rotor (step # 55), and the process proceeds to step # 60. On the other hand, if the maximum current amplitude electrical angle for the first rotation of the rotor and the maximum current amplitude electrical angle for the second rotation of the rotor are the same or substantially the same (YES in step # 54), the process proceeds to step # 70.

  The above-described modification of the first embodiment can also be implemented as a modification of this embodiment. In Step # 54, when the maximum current amplitude electrical angle of the first rotation of the rotor and the maximum current amplitude electrical angle of the second rotation of the rotor are not the same or substantially the same electrical angle (NO in Step # 54), Further, returning to step # 60, the maximum current amplitude electrical angle for the third rotation of the rotor is similarly determined. In step # 54, the maximum current amplitude electrical angle for the first rotation of the rotor and the maximum current amplitude electrical angle for the third rotation of the rotor are determined. Are the same or substantially the same electrical angle, and the maximum current amplitude electrical angle of the first rotation of the rotor and the maximum current amplitude electrical angle of the third rotation of the rotor are the same or substantially the same electrical angle. The process may move to step # 70. In this way, the electrical angle at which the current amplitude becomes the maximum value can be determined earlier. It should be noted that the number of the maximum current amplitude electrical angles that are the same or substantially the same for each rotation of the rotor is not limited to two but may be an arbitrary number of two or more.

<Third Embodiment>
The motor control device according to the third embodiment of the present invention is obtained by changing the correction processing content of Step # 70 with respect to the motor control device according to the first embodiment of the present invention. Note that it is possible to make the same changes to the motor control device according to the second embodiment of the present invention.

  In the present embodiment, the synchronous motor 4 is a three-phase six-pole motor, and the current amplitude on the U-phase upper side and the current amplitude on the lower U-phase side are detected for each electrical cycle in step # 30. For this reason, the current amplitude detection interval is an electrical angle of 180 degrees, and the rotor mechanical angle of 360 degrees is, as shown in FIG. 5A, six sections within the range of the electrical angle of 180 degrees, specifically, the first cycle U Section I centered on the electrical angle where the current amplitude of the upper phase was detected, Section II centered on the electrical angle where the current amplitude of the lower U phase of the first cycle was detected, Current amplitude of the upper U phase of the second cycle Section III centered on the electrical angle at which the current was detected, Section IV centered on the current amplitude on the U phase lower side of the second cycle, and the electrical angle on which the current amplitude on the upper side of the U phase in the third cycle was detected Is divided into a section V centered on the electrical angle at which the current amplitude on the lower side of the U phase in the third period is detected.

  The current amplitude A0 that takes the maximum value extracted in step # 50 is not the true maximum value, and there is a possibility that the current amplitudes A1 to A4 of the surrounding V phase or W phase that are not detection targets are true maximum values. In addition, when the electrical angle corresponding to the mechanical angle of the rotor, at which the motor drive current will be the maximum value, is closer to the boundary of the above section, the current amplitude A5 or A6 of the U phase that is the adjacent detection target is the current. There is a possibility that the amplitude is larger than A0. For this reason, even if the current amplitudes A1 to A4 are true maximum values or the current amplitude A5 or the current amplitude A6 is the maximum value to be extracted, the electrical angle at which the current amplitude takes the true maximum value is determined. The voltage command value can be corrected within a central electric angle range of 120 degrees. Thereby, the pulsation of the motor drive current can be more reliably suppressed. Specifically, the current amplitude detection interval, that is, the electrical angle 180 degrees that is the range of each section, is respectively before and after the range of the electrical angle 120 degrees around the current amplitude A0 that takes the maximum value extracted in step # 50. Add a range of. Therefore, the correction range of the voltage command value in the present embodiment is a range of 480 degrees electrical angle with the current amplitude A0 taking the maximum value extracted in step # 50 as the center. This correction range (range of electrical angle 480 degrees) corresponds to 44.4% of one rotation of the rotor (range of electrical angle 1080 degrees).

  When the synchronous motor 4 is changed from a three-phase six-pole motor to a three-phase four-pole motor, the current amplitude detection interval is 180 degrees as in the case of using a three-phase six-pole motor, but the rotor rotates once. Since there are two electrical angle cycles, the correction range (electrical angle range of 480 degrees) corresponds to 66.7% of one rotation of the rotor (electrical angle range of 720 degrees).

  Further, with the synchronous motor 4 remaining as a three-phase six-pole motor, in step # 30, the U-phase upper current amplitude, the V-phase upper current amplitude, and the W-phase upper current amplitude are detected for each electrical cycle. The case where it changed is demonstrated. In this case, the current amplitude detection interval is an electrical angle of 120 degrees, and the rotor mechanical angle of 360 degrees is, as shown in FIG. 6, nine sections in the range of the electrical angle of 120 degrees, specifically, the first cycle U Section I centered on the electrical angle where the current amplitude on the upper side of the phase was detected, Section II centered on the electrical angle where the current amplitude on the upper side of the V phase in the first cycle was detected, and current amplitude on the upper side of the W phase in the first cycle Section III centered on the detected electrical angle, Section IV centered on the current amplitude above the U phase in the second cycle, centered on the electrical angle detected the current amplitude above the V phase in the second cycle Section V, Section VI centered on the electrical angle at which the current amplitude on the upper side of the W phase in the second cycle was detected, Section VII, 3 centered on electrical angle at which the current amplitude on the upper side of the U phase in the second cycle was detected Section VIII, centered on the electrical angle at which the current amplitude on the V phase upper side of the cycle is detected, on the W phase of the third cycle Segmented electrical angle detected current amplitude of the section IX centered.

  The current amplitude A0 that takes the maximum value extracted in step # 50 is not the true maximum value, and the lower current amplitudes A1 and A2 that are not detection targets in the surrounding area may be the true maximum value. When the electrical angle corresponding to the mechanical angle of the rotor at which the current will be the maximum is closer to the boundary of the above section, the upper current amplitude A3 or A4 that is the adjacent detection target is more than the current amplitude A0. There is a big possibility. Therefore, even if the current amplitudes A1 and A2 are true maximum values, or the current amplitude A3 or the current amplitude A4 is the maximum value to be extracted, the electrical angle at which the current amplitude takes the true maximum value is determined. The voltage command value can be corrected within a central electric angle range of 120 degrees. Thereby, the pulsation of the motor drive current can be more reliably suppressed. Specifically, the current amplitude detection interval, that is, the electrical angle 120 degrees that is the range of each section, is respectively before and after the range of the electrical angle 120 degrees centering on the current amplitude A0 that takes the maximum value extracted in step # 50. Add a range of. Therefore, the correction range of the voltage command value in the present embodiment is a range of 360 electrical degrees with the current amplitude A0 taking the maximum value extracted in step # 50 as the center. This correction range (range of electrical angle 360 degrees) corresponds to 33.3% of one rotation of the rotor (range of electrical angle 1080 degrees).

  As described above, in step # 30, in the specification for detecting the current amplitude on the upper side of the U phase, the current amplitude on the upper side of the V phase, and the current amplitude on the upper side of the W phase in each electrical cycle, the synchronous motor 4 is changed from a motor with three phases and six poles. When the motor is changed to a three-phase four-pole motor, the current amplitude detection interval is the same as when a three-phase six-pole motor is used. However, since the rotation of the rotor is equivalent to two electrical angles, the correction range (electrical angle 360) The range of degrees corresponds to 50.0% of one rotation of the rotor (range of electric angle 720 degrees).

  Further, with the synchronous motor 4 remaining as a three-phase six-pole motor, in step # 30, the current amplitude on the upper U phase, the current amplitude on the lower U phase, the current amplitude on the upper V phase, and the lower phase on the V phase for each electrical cycle. A case will be described where the current amplitude of the current phase, the current amplitude of the upper side of the W phase, and the current amplitude of the lower side of the W phase are detected. In this case, the current amplitude detection interval is an electrical angle of 60 degrees, and the rotor mechanical angle of 360 degrees is, as shown in FIG. 7, 18 sections in the range of the electrical angle of 60 degrees, specifically, the first cycle U Section I centered on the electrical angle where the current amplitude on the upper side of the phase was detected, Section II centered on the electrical angle where the current amplitude on the lower side of the W phase in the first cycle was detected, Current amplitude on the upper side of the V phase in the first cycle Section III centered on the electrical angle where the current was detected, Section IV centered on the electrical angle where the current amplitude on the U phase under the first cycle was detected, and the electrical angle where the current amplitude on the upper side of the W phase in the first cycle was detected Section V centered on the first section, Section VI centered on the electrical angle at which the current amplitude on the lower side of the V phase in the first cycle was detected, and Sections centered on the electrical angle on which the current amplitude on the upper side of the U phase in the second period was detected Section VII, centered on the electrical angle at which the current amplitude on the lower side of the W phase in the second cycle is detected, and the upper side of the V phase in the second cycle Section IX centered on the electrical angle where the current amplitude was detected, Section X centered on the electrical angle where the current amplitude below the U phase in the 2nd cycle was detected, and detected the current amplitude above the W phase in the 2nd cycle Section XI centered on the electrical angle, Section XII centered on the electrical angle where the current amplitude on the lower side of the V phase in the second cycle was detected, Centered on the electrical angle detected on the current amplitude on the upper side of the U phase in the third period Section XIII, section XIV centered on the electrical angle at which the current amplitude on the lower side of the W phase in the third period is detected, and section XV centered on electrical angle at which the current amplitude on the upper side of the V phase in the third period was detected. Section XVI centered on the electrical angle at which the current amplitude of the lower U phase in the cycle was detected, Section XVII centered on the electrical angle of the current amplitude on the upper side of the W phase in the third cycle, V phase in the third cycle The section is divided into section XVIII centered on the electrical angle at which the lower current amplitude is detected.

  When the electrical angle corresponding to the mechanical angle of the rotor at which the motor driving current will be the maximum value is close to the boundary of the above section, the current amplitude A0 that takes the maximum value extracted in step # 50 is the true maximum value. Instead, there is a possibility that the current amplitudes A1 and A2 that are adjacent detection targets are true maximum values. For this reason, even if the current amplitude A1 or the current amplitude A2 is a true maximum value, the voltage command value can be corrected in an electric angle range of 120 degrees centering on the electrical angle at which the current amplitude takes the true maximum value. Like that. Thereby, the pulsation of the motor drive current can be more reliably suppressed. Specifically, the current amplitude detection interval, that is, the electrical angle 60 degrees that is the range of each section, is respectively before and after the range of the electrical angle 120 degrees centering on the current amplitude A0 that takes the maximum value extracted in step # 50. Add a range of. Therefore, the correction range of the voltage command value in the present embodiment is a range of an electrical angle of 240 degrees centering on the current amplitude A0 that takes the maximum value extracted in step # 50. This correction range (range of electrical angle of 240 degrees) corresponds to 22.2% of one rotation of the rotor (range of electrical angle of 1080 degrees).

  As described above, in step # 30, the current amplitude above the U phase, the current amplitude below the U phase, the current amplitude above the V phase, the current amplitude below the V phase, the current amplitude above the W phase, and When the synchronous motor 4 is changed from the three-phase six-pole motor to the three-phase four-pole motor in the specification for detecting the current amplitude on the lower side of the W phase, the current amplitude detection interval is the case where a three-phase six-pole motor is used. Similarly, since one rotation of the rotor is equivalent to two cycles of electrical angle, the correction range (range of electrical angle 240 degrees) corresponds to 33.3% of one rotation of rotor (range of electric angle 720 degrees).

  As described in the first embodiment, when the correction range (electrical angle range for reducing the motor drive voltage) is as narrow as possible, the motor torque is prevented from being lowered and the set acceleration rate is not greatly impaired. Accordingly, the ratio of the correction range in one rotation of the rotor is preferably low. For example, if the correction range is 50% or less, the range in which the motor torque is not reduced becomes wider than the range in which the motor torque is reduced, so that acceleration is unlikely to be insufficient. be able to. That is, the correction amount of the motor drive voltage and the current amplitude detection interval may be set so that the acceleration is completed within a predetermined acceleration completion time even if the acceleration that decreases due to the application of correction is taken into account.

<Fourth embodiment>
The motor control device according to the first to third embodiments of the present invention is not particularly limited with respect to the control after the completion of the motor start-up, but the motor control device according to the fourth embodiment of the present invention is the present invention during the motor start-up. The same control as in any of the first to third embodiments is performed, and the control described below is performed after the start of the motor is completed.

  The motor control apparatus according to the present embodiment includes a voltage correction pattern storage unit 12 as shown in FIG.

  The voltage correction pattern storage unit 12 stores a voltage correction pattern corresponding to an angle corresponding to one cycle of load torque fluctuation in the load element. For example, the voltage correction pattern may be stored in the form of a data table indicating the correspondence between the angle and the correction value, or may be stored in the form of a function indicating the correspondence between the angle and the correction value.

  The voltage correction pattern is set according to the load torque characteristic in the load element. An example of the voltage correction pattern is shown in FIG.

  The voltage correction pattern is a function obtained by integrating a value obtained by subtracting the value of the load torque at each angle of the load element driven by the synchronous motor 4 from the average value of one load torque cycle of the load element by the angle of the load element. Can be determined based on By determining in this way, the drive current of the synchronous motor 4 is not lowered by correcting and accelerating the drive voltage of the synchronous motor 4 at an angle where the value of the load torque is smaller than the average value. In addition, when the load torque value is larger than the average value, the drive current of the synchronous motor 4 can be prevented from increasing by correcting the drive voltage of the synchronous motor 4 so as to decrease and decelerating. Variations in the drive current of the synchronous motor 4 due to periodic load torque variations of the elements can be suppressed.

  In the example of FIG. 9, a voltage correction pattern corresponding to a load element having a load torque characteristic such as the reciprocating compressor shown in FIG. 1B is shown. FIG. 9A shows the load torque curve A for two cycles for the load elements similar to FIG. 1B. In FIG. 9A, the load torque average value B is a value obtained by averaging the load torque values for one cycle of the load torque curve A.

  A curve C in FIG. 9B is a curve obtained by calculating the value of (load torque average value B) − (load torque A) at each angle in the curve in FIG. When the motor is driven using such a curve C as a voltage correction pattern and a load element having the load torque characteristic curve A is driven, fluctuations in the drive current of the motor can be suppressed. At that time, it is desirable that the load torque curve A and the voltage correction pattern C are in phase, and further, the voltage correction amount by the voltage correction pattern C is preferably an appropriate amount with respect to the load torque characteristic curve A. .

  For this reason, when the curve C in FIG. 9B is stored in the voltage correction pattern storage unit 8 as a voltage correction pattern, the angle and the correction value are stored as a relative value instead of an absolute value, and the motor is driven in a normal operation. When correcting the motor drive voltage waveform by the voltage waveform correction unit 10, it is preferable to correct the motor drive voltage waveform by correction data obtained by giving a predetermined correction coefficient to the voltage correction pattern stored in the voltage correction pattern storage unit 12. . In FIG. 9B, as an example, a load torque fluctuation cycle of one load element sandwiched between dotted lines is used as a voltage correction pattern, and the left end of the angle axis (horizontal axis) is 0 degrees and the right end is 360 degrees. (Vertical axis) is stored in the voltage correction pattern storage unit 12 as normalized data in which the average of correction amounts for one period is 1.

  Note that the voltage correction pattern may have a shape approximating the curve C in FIG. 9B as shown in FIG. 9C. The shape of the load torque curve A shown in FIG. 9 (a) changes depending on the load condition, the number of revolutions, and the like, and in the case of mass-produced products, individual differences occur, so the voltage is strictly measured as shown in FIG. 9 (b). Even if a correction pattern is defined, it matches only under specific conditions. Therefore, even when an approximate shape as shown in FIG. 9C is used, in many cases, an effect that is not much different from the case where the voltage correction pattern shown in FIG. On the other hand, by using an approximate shape as shown in FIG. 9C, it is only necessary to store a functional expression without storing a large amount of table data as voltage correction pattern data. Since the function equation itself can be corrected, it is expected that the capacity of the voltage correction pattern storage unit 12 can be reduced and the correction process in the motor drive voltage waveform correction unit 10 can be speeded up. In the following description, it is assumed that the correction pattern shown in FIG. 9D based on the voltage correction pattern in FIG. 9C is stored in the voltage correction pattern storage unit 12.

  Next, a detailed operation in the normal operation of the motor drive voltage waveform correction unit 10 will be described. Hereinafter, the case where the synchronous motor 4 is a three-phase six-pole motor will be described. Further, it is assumed that one cycle of load torque fluctuation in the load element is one rotation of the synchronous motor 4. The motor drive voltage waveform correction unit 10 starts the flow operation shown in FIGS. 10A and 10B after the activation of the synchronous motor 4 is completed.

  First, the rotational speed setting unit 8 issues a command so that the synchronous motor 4 has a predetermined rotational speed, and confirms that the predetermined rotational speed has been reached (step S2). The predetermined rotation speed is set such that the motor drive current does not exceed the overcurrent threshold set in the overcurrent protection circuit without correcting the motor drive voltage. For example, the above-described stable rotational speed is preferable.

  Next, the motor drive voltage waveform correction unit 10 cancels the correction of the motor drive basic voltage waveform described in the first to third embodiments (step S4). As a result, the pulsation amount (variation amount) of the motor drive current waveform is easily generated.

  Next, the motor drive voltage waveform correction unit 10 grasps the phase angle at which the correction amount of the voltage correction pattern is maximized (step S6). For example, when the correction pattern shown in FIG. 9D is stored in the voltage correction pattern storage unit 12, the correction amount is the maximum at the phase angle of about 260 degrees of the voltage correction pattern.

  Next, the motor drive voltage waveform correction unit 10 grasps the electrical angle range (acceleration corrected electrical angle range) in which the motor drive basic voltage waveform described in the first to third embodiments is corrected (step S8). . Note that step S6 and step S8 need not be performed in the order shown in FIG. 10A, but may be stored in a predetermined storage area in advance, and called as necessary in a later step.

  Next, the motor drive voltage waveform correction unit 10 sets the initial value of the phase shift amount θ to 0 and the initial value of the correction gain M to 1 (step S10). Thereafter, the motor drive voltage waveform correction unit 10 reads a voltage correction pattern from the voltage correction pattern storage unit 8 (step S20).

  Next, the motor drive voltage waveform correction unit 10 multiplies the correction amount for each angle of the voltage correction pattern by the correction gain M (step S30). Then, the phase of the voltage correction pattern is shifted by θ ° with respect to the phase of the motor drive basic voltage waveform (step S40).

  Next, the motor drive voltage waveform correction unit 10 determines whether or not the phase angle at which the correction amount of the voltage correction pattern shifted by θ ° is within the acceleration corrected electrical angle range (step S41). ). For example, in the correction pattern shown in FIG. 9D, the phase angle of about 260 degrees is the phase angle at which the correction amount is maximum. In the present embodiment, since the synchronous motor 4 is a three-phase six-pole motor, the voltage correction pattern shifted by θ ° is converted into an electrical angle and the correction amount is (θ ° + 260 °) × 3 electrical angle. Maximum. When this electrical angle is within the corrected electrical angle range during acceleration, correction is performed to increase the voltage to the electrical angle where the current amplitude is likely to be maximized, and the pulsation amount of the motor drive current waveform ( There is a high possibility of large fluctuations). Therefore, when the electrical angle range in which the pulsation amount (fluctuation amount) of the motor drive current waveform is likely to be large is known in this way, the phase angle at which the correction amount of the voltage correction pattern is maximized is included in the range. By avoiding this, the phase shift correction coefficient of the voltage correction pattern can be obtained while suppressing the pulsation amount (variation amount) of the motor drive current waveform.

  For example, when the correction range shown in the first embodiment (FIG. 5A) is a correction range for reducing the motor drive voltage when the synchronous motor 4 is started up, the acceleration correction electric angle range is an electrical angle of 210 degrees or more. It is 690 degrees. Therefore, if the electrical angle when the correction pattern shown in FIG. 9D is shifted by the phase shift amount θ degrees is within the above-mentioned acceleration correction electrical angle range (YES in step S41), the pulsation of the motor drive current waveform Do not detect quantity. That is, if θ is a phase angle of −190 degrees to −30 degrees, that is, θ is 170 degrees to 330 degrees, step S50 and step S60 described later are skipped, and the process proceeds to step S70 described later.

  Next, the motor drive voltage waveform correction unit 10 performs voltage correction at each angle corresponding to one rotation of the load element (each angle may be a discrete value or a continuous value). The amplitude and angular velocity of the motor drive basic voltage waveform are corrected according to the pattern correction value. The larger the voltage correction pattern correction value, the larger the motor drive basic voltage waveform amplitude and the motor drive basic voltage waveform angular velocity. Thus, the smaller the correction value of the voltage correction pattern, the smaller the amplitude of the motor drive basic voltage waveform and the smaller the angular velocity of the motor drive basic voltage waveform (step S50).

  Here, FIG. 5B shows motor drive voltage waveforms of the respective phases after the correction is performed in step S50 after the activation according to the first embodiment (FIG. 5A). In FIG. 5B, the voltage correction pattern P is also shown together with the motor drive voltage waveforms Vu, Vv, Vw of each phase after correction. The corrected motor drive voltage waveforms Vu, Vv, and Vw shown in FIG. 5B are waveforms obtained by correcting only the amplitude of the motor drive voltage waveform according to the correction value of the voltage correction pattern P at each angle. By correcting the amplitude of the motor drive voltage waveform according to the correction value of the voltage correction pattern at each angle, as shown in FIG. 5B, the motor drive voltage waveform is reduced from the section expanding in the vertical axis direction. You can make a section. Further, by correcting the angular velocity of the motor drive voltage waveform according to the correction value of the voltage correction pattern at each angle, although not shown, the motor drive voltage waveform is expanded in the horizontal axis direction. You can make a section that is shrinking.

  In step S60 following step S50, the motor drive voltage waveform correction unit 10 drives each phase of the motor in a state where the synchronous motor 4 is driven based on the motor drive voltage waveform of each phase corrected in the process of step S50. The current is read from the motor drive current storage unit 7 for one rotation of the motor, that is, one cycle of load torque fluctuation in the load element, and the pulsation amount (fluctuation amount) of the motor drive current waveform is calculated. The motor drive current value of each phase is obtained by reading a value at a predetermined angle in each phase from the motor drive current of each phase estimated by the motor drive current estimation unit 6. The predetermined angle is an angle at which the motor driving current is estimated to be maximized based on the motor driving voltage waveform. For example, the angle at which the value of the motor driving current is read has a peak in the motor driving basic voltage waveform of each phase. It is good also as an angle. If the phase delay amount of the motor drive current with respect to the motor drive voltage waveform is known or can be estimated, the angle at which the motor drive current value is read is the angle at which the motor drive basic voltage waveform of each phase peaks. The angle obtained by adding the amount of phase delay can be obtained. As a result, the value of the motor drive current can be read at an angle closer to the angle at which the motor drive current waveform peaks, and the pulsation amount of the motor drive current waveform can be determined with higher accuracy.

  The reading of the motor drive current waveform is not limited to the above, and for example, the current amplitude of each phase may be detected as in the above-described embodiment. For example, as shown in FIG. 7, the pulsation amount of the motor drive current waveform can be obtained by selecting the maximum and minimum values from the 18-point data of the three-phase motor drive current waveform and taking the difference. Further, the reading angle is determined not only by the angle based on the motor driving voltage waveform of each phase, but can also be determined based on the angle at which the motor driving current becomes zero-crossed or peaked.

  FIG. 11A shows motor drive when the motor drive voltage waveform is corrected by a voltage correction pattern in which the phase shift amount θ = 0 ° and the correction gain M = 1 is added to the correction pattern shown in FIG. It is an example of an electric current. In the example shown in FIG. 11, the case where a three-phase four-pole motor is used as the synchronous motor is shown, and one rotation of the rotor is equivalent to two cycles of the electric angle of the synchronous motor. Since the motor and load element driven in FIG. 11 are different from the motor and load element in FIG. 9 when the voltage correction pattern is obtained in advance, in the example of FIG. There is a large difference between the maximum value of the current waveform (absolute value of Iw2) and the minimum value of the motor drive current waveform (absolute value of Iu4), and the motor drive current pulsates greatly. In step S60, the difference between the maximum value of the motor drive current waveform (in this case, the absolute value of Iw2) and the minimum value of the motor drive current waveform (in this case, the absolute value of Iu4), and the phase shift amount θ (this In this case, θ = 0 °) is stored.

  Next, the motor drive voltage waveform correction unit 10 determines whether (θ + Δθ) is equal to or greater than 360 ° (step S70). Here, Δθ is the phase shift width of the voltage correction pattern. If this value is reduced, the phase correction coefficient of the voltage correction pattern can be obtained more accurately. If this value is increased, the number of trials (the number of executions of steps S40 to S80) for obtaining the phase shift correction coefficient of the voltage correction pattern can be reduced. In this embodiment, since Δθ = 2 °, steps S40 to S80 are executed a maximum of 180 times.

  If (θ + Δθ) is not 360 ° or more (NO in step S70), motor drive voltage waveform correction unit 10 sets a value obtained by adding Δθ to the current value of θ as a new value of θ (step S80). Then, the process returns to step S40. On the other hand, if (θ + Δθ) is 360 ° or more (YES in step S70), for example, the relationship between the pulsation amount of the motor drive current and the phase shift amount of the voltage correction pattern as shown in FIG. 12 is obtained. The motor drive voltage waveform correction unit 10 sets the phase shift amount of the voltage correction pattern that minimizes the pulsation amount of the motor drive current to the phase correction coefficient θ0 of the voltage correction pattern (step S90). In the example shown in FIG. 12, since the pulsation amount of the motor drive current is minimized when θ = 60 °, the phase correction coefficient θ0 of the voltage correction pattern is set to 60 °.

  In the present embodiment, when the phase angle at which the correction amount of the voltage correction pattern is maximized when the phase shift amount is shifted by θ degrees is in the acceleration correction electrical angle range (YES in step S41), the motor The pulsation amount of the drive current is not detected. Therefore, in the example of FIG. 12, in the range of 0 to 20 ° and the range of 260 ° to 360 °, detection of the pulsation amount of the motor drive current is skipped and there is no data. However, what is desired is the phase shift amount of the voltage correction pattern that minimizes the pulsation amount of the motor drive current, whereas the pulsation amount of the motor drive current increases in the range of θ skipped in step S41. Is known and not useful. In the example shown in FIG. 12, when the phase shift amount θ is in the range of 0 ° to 20 ° and in the range of 260 ° to 360 °, detection of the pulsation amount of the motor drive current is skipped and there is no data, but the remaining phase shift amount θ Can be sufficiently determined that the pulsation amount of the motor drive current is minimized when θ = 60 °. Therefore, the pulsation amount of the motor drive current should not be detected in the range of the phase shift amount that is unlikely to be useful for detecting the phase shift amount of the voltage correction pattern that minimizes the pulsation amount of the motor drive current. Thus, it is possible to efficiently obtain the phase shift correction coefficient of the voltage correction pattern while suppressing the pulsation amount (variation amount) of the motor drive current waveform and reducing the number of detections of the pulsation amount of the motor drive current.

  As long as the drive of the synchronous motor 4 continues, the value of the phase shift amount of the voltage correction pattern that minimizes the pulsation amount of the motor drive current often does not change greatly. For this reason, it is not necessary to reset the phase correction coefficient of the voltage correction pattern determined in step S90 while the synchronous motor 4 continues to rotate. Therefore, in the flowcharts of FIGS. 10A and 10B, the process of step S90 is performed only once. Depending on the load element, the value of the phase shift amount of the voltage correction pattern that minimizes the pulsation amount of the motor drive current may vary depending on the load torque amount and the rotation speed. In this case, step S10 is performed again under the conditions. The phase correction coefficient setting process of the voltage correction pattern starting from the above may be performed.

  In step S100 following step S90, the motor drive voltage waveform correction unit 10 shifts the phase of the voltage correction pattern by the phase correction coefficient θ0 obtained in step S90 with respect to the phase of the motor drive basic voltage waveform.

  Next, the motor drive voltage waveform correction unit 10 multiplies the correction amount for each angle of the voltage correction pattern by the correction gain M (step S110). Then, the motor drive voltage waveform correction unit 10 multiplies each angle (each angle may be a discrete value or may be a continuous value) by a correction gain M to obtain a phase. The amplitude and angular velocity of the motor drive voltage waveform are corrected according to the correction value of the voltage correction pattern shifted by the phase correction coefficient θ0, and the amplitude of the motor drive voltage waveform increases as the correction value of the voltage correction pattern at each angle increases. In order to increase the angular velocity of the motor drive voltage waveform, the smaller the correction value of the voltage correction pattern, the smaller the amplitude of the motor drive voltage waveform and the smaller the angular velocity of the motor drive voltage waveform (step S120).

  In step S130 subsequent to step S120, the motor drive voltage waveform correction unit 10 drives each phase of the motor in a state where the synchronous motor 4 is driven based on the motor drive voltage waveform of each phase corrected in the process of step S120. The current is read from the motor drive current storage unit 7 for one rotation of the motor, that is, one cycle of load torque fluctuation in the load element, and the pulsation amount (fluctuation amount) of the motor drive current waveform is calculated.

  Next, the motor drive voltage waveform correction unit 10 compares the pulsation amount of the current motor drive current waveform with the pulsation amount of the previous motor drive current waveform, and determines whether the difference is equal to or less than a predetermined value (step S140). ). If the difference is not less than the predetermined value (NO in step S140), it is determined that the minimum value of the pulsation amount of the motor drive current waveform has not been found, and the process proceeds to step S150. On the other hand, if the difference is equal to or smaller than the predetermined value (YES in step S140), it is determined that the minimum value of the pulsation amount of the motor drive current waveform has been found, and the process proceeds to step S200.

  In step S150, the pulsation amount of the current motor drive current waveform is compared with the pulsation amount of the previous motor drive current waveform, and it is determined whether the difference is equal to or less than a predetermined value. Here, the predetermined value used in the determination in step S150 is set to a value larger than the predetermined value used in the determination in step S140. If the difference is equal to or smaller than the predetermined value (YES in step S150), it is determined that the current correction gain M is approaching the gain correction coefficient M0 at which the pulsation amount of the motor drive current waveform becomes the minimum value, and the correction gain The amount of the step width ΔM of M is halved (step S160), and then the process proceeds to step S170. On the other hand, if the difference is not less than or equal to the predetermined value (NO in step S150), it is determined that the current correction gain M is still separated, and the process proceeds to step S170 while maintaining the amount of step width ΔM of the correction gain M. Transition.

  In step S170, it is determined whether or not the pulsation amount of the current motor drive current waveform is smaller than the pulsation amount of the previous motor drive current waveform. If the current pulsation amount is larger than the previous current pulsation amount (NO in step S170), the next increase / decrease direction of the correction gain M is set to the opposite direction (step S180), and the process proceeds to step S190. On the other hand, if the current pulsation amount is smaller than the previous current pulsation amount (YES in step S170), the next increase / decrease direction of the correction gain M remains the same as the previous one, and the process proceeds to step S190. In step S190, M is changed by the increment ΔM of the correction gain M, and the process returns to step S110.

  In step S200, the correction gain M is set to the gain correction coefficient M0 of the voltage correction pattern. In the example shown in FIG. 13, since the pulsation amount of the motor drive current is minimized when M = 2, the gain correction coefficient M0 of the voltage correction pattern is set to 2.

  FIG. 11B shows the motor drive when the motor drive voltage waveform is corrected by the voltage correction pattern in which the phase shift amount θ = 60 ° and the correction gain M = 2 is added to the correction pattern shown in FIG. It is an example of an electric current. In the example of FIG. 11B, all the crest values of the motor drive current waveform are aligned, and the motor drive current does not pulsate (the pulsation amount = 0 in FIG. 13).

  In step S210 following step S200, the motor drive voltage waveform correction unit 10 determines that the synchronous motor 4 is based on the motor drive voltage waveform of each phase corrected with the voltage correction pattern given the phase correction coefficient θ0 and the gain correction coefficient M0. The motor drive current of each phase in the driving state is read from the motor drive current storage unit 7 for one rotation of the motor, that is, one cycle of load torque fluctuation in the load element, and the minimum amplitude value is subtracted from the maximum amplitude value of the motor drive current. The calculated value is calculated as the pulsation amount (variation amount) of the motor drive current waveform. Subsequently, in step S220, it is determined whether or not the calculated pulsation amount of the motor drive current waveform is equal to or less than a predetermined value. If the pulsation amount is equal to or smaller than the predetermined value (YES in step S220), it is determined that the motor drive voltage waveform is optimally corrected, and the process returns to step S210. If the pulsation amount is not less than or equal to the predetermined value (NO in step S220), it is determined that the motor drive voltage waveform is not optimally corrected, and the gain correction coefficient M0 is substituted for the correction gain M (step S230). Returning, the search for the gain correction coefficient M0 is performed again.

  Note that instead of or in addition to steps S210 to S230, for example, a step of forcibly re-exploring the gain correction coefficient M0 may be provided every time a predetermined time elapses. Further, step S210 may be performed at any time or intermittently at predetermined time intervals.

  Also, depending on the load element, the value of the phase shift amount of the voltage correction pattern that minimizes the pulsation amount of the motor drive current may vary depending on the load torque amount and the rotation speed. In this case, the process may return to step S10.

  When the motor drive voltage waveform correction unit 10 performs the operations of the flowcharts shown in FIGS. 10A and 10B described above, information on the connection position of the synchronous motor 4 and the load element driven by the synchronous motor 4 without the position sensor, that is, the synchronous motor Even if there is no information regarding the relationship between the electrical angle of 4 and the mechanical angle of the load element driven by the synchronous motor 4, the amount of pulsation of the motor drive current can be reduced (ideally zero). Can be driven with high efficiency.

  Further, the motor drive voltage waveform correction unit 10 performs the operations of the flowcharts shown in FIGS. 10A and 10B described above, so that even if there is no information about the change in the load torque amount, the motor drive voltage waveform correction unit 10 is driven in response to the change in the load torque amount. The amount of current pulsation can be reduced (ideally zero), and the synchronous motor 4 can be driven with high efficiency.

  Further, the motor drive voltage waveform correction unit 10 performs the operations of the flowcharts shown in FIGS. 10A and 10B described above to correct one voltage correction pattern with two correction coefficients (phase correction coefficient and gain correction coefficient). Since the motor torque of the synchronous motor 4 can be controlled, the motor control can be controlled easily and continuously.

<Fifth Embodiment>
The schematic configuration of the motor control device according to the fifth embodiment of the present invention is the same as the schematic configuration of the motor control device according to the fourth embodiment of the present invention. The motor control device according to the present embodiment performs the same control as that of any of the first to third embodiments of the present invention during the startup of the motor, and further performs the control described below after the completion of the startup of the motor.

  In the present embodiment, the motor drive voltage waveform correction unit 10 performs the operations of the flowcharts shown in FIGS. 14A and 14B after the start of the synchronous motor 4 is completed. 14A and 14B is a first modification in which steps S6 and S10 are replaced with steps S7 and S11, and steps S40 to S90 are replaced with steps S40 to S91 with respect to the flowcharts illustrated in FIGS. 10A and 10B. And a second change to be replaced. When the motor drive voltage waveform correction unit 10 performs the operations of the flowcharts shown in FIGS. 14A and 14B, the motor control device according to the present embodiment has the same effects as the motor control device according to the fourth embodiment of the present invention. Play.

  Hereinafter, the operation of the motor drive voltage waveform correction unit 10 related to the first to second changes will be described, and the operation of the motor drive voltage waveform correction unit 10 related to other than the first to second changes will be described in the fourth embodiment of the present invention. The description is omitted because it is the same.

  When the process of step S4 ends, the motor drive voltage waveform correction unit 10 grasps the phase angle at which the correction amount of the voltage correction pattern is minimized (step S7). For example, when the correction pattern shown in FIG. 9D is stored in the voltage correction pattern storage unit 12, the correction amount is minimum at the phase angle of the voltage correction pattern of about 0 degrees.

  In the next step S11, an initial value of the phase shift amount θ is set based on the acceleration corrected electrical angle range obtained in the subsequent step S8. As in the first embodiment, when the acceleration correction electrical angle range is 210 to 690 degrees, for example, the voltage correction pattern is set to an electrical angle of 450 degrees, which is the median value of the acceleration correction electrical angle range. The initial value of the phase shift amount θ is set so that the minimum value is reached. That is, as in the fourth embodiment, when the synchronous motor 4 is a three-phase six-pole motor, an equation converted to an electrical angle, (θ ° + 0 °) × 3 = 450 °, a phase shift amount θ = 150. Assuming that the phase angle is an electrical angle that is the central value of the corrected electrical angle range during acceleration, the phase angle at which the correction amount of the voltage correction pattern is the minimum value comes, so this phase shift amount θ is set as an initial value. In step S11, the motor drive voltage waveform correction unit 10 sets the initial value of the correction gain M to 1.

  In step S61, the motor drive voltage waveform correction unit 10 compares the pulsation amount of the current motor drive current waveform with the pulsation amount of the previous motor drive current waveform, and determines whether the difference is equal to or less than a predetermined value. If the difference is not less than the predetermined value (NO in step S61), it is determined that the minimum value of the pulsation amount of the motor drive current waveform has not been found, and the process proceeds to step S62. On the other hand, if the difference is equal to or smaller than the predetermined value (YES in step S61), it is determined that the minimum value of the pulsation amount of the motor drive current waveform has been found, and the process proceeds to step S91.

  In step S62, the pulsation amount of the current motor drive current waveform is compared with the pulsation amount of the previous motor drive current waveform, and it is determined whether the difference is equal to or less than a predetermined value. Here, the predetermined value used in the determination in step S62 is set to a value larger than the predetermined value used in the determination in step S61. If the difference is equal to or smaller than the predetermined value (YES in step S62), it is determined that the current phase shift amount θ is approaching the phase shift amount θ0 at which the pulsation amount of the motor drive current waveform is the minimum value, and the phase The step amount Δθ of the shift amount θ is halved (step S63), and then the process proceeds to step S64. On the other hand, if the difference is not less than or equal to the predetermined value (NO in step S62), it is determined that the current phase shift amount θ is still separated, and the step of the step width Δθ of the phase shift amount θ is maintained. The process proceeds to S64.

  In step S64, it is determined whether or not the pulsation amount of the current motor drive current waveform is smaller than the pulsation amount of the previous motor drive current waveform. If the current pulsation amount is larger than the previous current pulsation amount (NO in step 64), the next phase shift amount θ is increased or decreased in the opposite direction (step S65), and the process proceeds to step S66. On the other hand, if the current pulsation amount is smaller than the previous current pulsation amount (YES in step S64), the next phase shift amount θ is increased or decreased in the same direction as the previous time, and the process proceeds to step S66. In step S66, θ is changed by the increment Δθ of the phase shift amount θ, and the process returns to step S40. As a result, if the difference between the pulsation amount of the current motor drive current waveform and the pulsation amount of the previous motor drive current waveform is equal to or smaller than the predetermined value set in step S61, the routine from step S40 to step S66 is performed for one rotation of the motor. That is, even if one load torque fluctuation period in the load element is not completed, the routine of Steps S40 to S66 can be exited, and the processing time can be shortened.

  Furthermore, in the present embodiment, the initial value of the phase shift amount θ is set so that the phase angle at which the correction amount of the voltage correction pattern is the minimum is within the corrected electrical angle range during acceleration. That is, since the phase angle that minimizes the correction amount of the voltage correction pattern comes within the electrical angle range where the motor drive current is known to be large, the pulsation amount of the motor drive current is already suppressed The routine to calculate the phase shift correction coefficient of the voltage correction pattern can be started from this, while suppressing the pulsation amount (variation amount) of the motor drive current waveform and reducing the number of detections of the pulsation amount of the motor drive current. It is possible to obtain the phase shift correction coefficient of the voltage correction pattern.

  In step S91, the motor drive voltage waveform correction unit 10 sets the phase shift amount θ to the phase correction coefficient θ0 of the voltage correction pattern.

<Sixth Embodiment>
The sixth embodiment of the present invention differs from the fourth embodiment of the present invention in the method of defining the voltage correction pattern, and is otherwise the same as the fourth embodiment of the present invention.

  In this embodiment, when the load element is rotated with a constant torque (motor torque is constant), a change in angular velocity for one cycle of load torque fluctuation is measured, and a voltage correction pattern is determined based on the fluctuation pattern.

  When the load element is driven with a constant torque, the angular speed increases at a mechanical angle at which the load torque is smaller than the average load torque, and the angular speed decreases at a mechanical angle at which the load torque is greater than the average load torque. When the force is integrated, velocity energy is obtained, so that even the voltage correction pattern defined by the definition method in the present embodiment is the same as the voltage correction pattern in the first embodiment of the present invention. Therefore, the motor control device according to the present embodiment has the same effects as the motor control device according to the first embodiment of the present invention, and a correction pattern can be obtained without measuring the load torque curve. The voltage correction pattern can be defined more easily than in the first embodiment.

<Seventh embodiment>
The seventh embodiment of the present invention is different from the fourth and sixth embodiments of the present invention in the definition method of the voltage correction pattern, and the other embodiments are the same as the fourth and sixth embodiments of the present invention. Are the same.

  In this embodiment, the voltage with which the correction amount of the voltage correction pattern itself (correction amount when the correction gain amount M = 1) is smaller than the voltage correction pattern defined in the fourth or sixth embodiment of the present invention. Define the correction pattern. For example, the voltage correction pattern defined in the first embodiment of the present invention multiplied by a predetermined correction gain amount greater than 0 and smaller than 1 may be used as the voltage correction pattern of the present embodiment, and the third embodiment of the present invention. The voltage correction pattern defined in the above may be multiplied by a predetermined correction gain amount greater than 0 and less than 1 as the voltage correction pattern of this embodiment.

  As a result, when searching for the phase correction coefficient with M = 1 (steps S10 to S90 in the fourth embodiment), the voltage correction amount is too large and the motor drive becomes unstable, and in the worst case, step-out occurs. This can be prevented. Further, since it is almost certain that the gain correction coefficient is 1 or more when searching for the gain correction coefficient (steps S100 to S200 in the fourth embodiment), steps S170 and S180 can be omitted. There is also an advantage that a gain correction coefficient can be obtained quickly. The definition of the voltage correction pattern is not changed from the fourth or sixth embodiment of the present invention, but the initial correction gain amount M at the time of searching for the phase correction coefficient and the gain correction coefficient is made smaller than 1. Also, the same effect as described above can be obtained.

  The correction amount of the voltage correction pattern itself defined in the present embodiment (the correction amount when the correction gain amount M = 1) is the correction amount of the voltage correction pattern itself defined in the first embodiment or the third embodiment of the present invention. It is preferable to set it to half or less of (correction amount when correction gain amount M = 1). In this case, since it can be predicted that the gain correction coefficient will be 2 or more, the gain correction coefficient can also be used as one of judgment materials when searching for the gain correction coefficient (steps S100 to S200).

<Eighth Embodiment>
In the fourth embodiment of the present invention, the voltage correction pattern corresponding to the load element having the load torque characteristic such as the reciprocating compressor shown in FIG. 9 is given as an example of the voltage correction pattern. In the embodiment, a voltage correction pattern corresponding to a load element having load torque characteristics such as a single rotor type compressor shown in FIG. 1A is used.

  FIG. 15A shows a load torque characteristic for one cycle for a load element having a load torque characteristic such as the single rotor type compressor shown in FIG. 1A. In FIG. 15A, the load torque average value B is a value obtained by averaging the load torque values for one cycle of the load torque curve A.

  A curve C in FIG. 15B is a curve obtained by calculating the value of (load torque average value B) − (load torque A) at each angle in the curve in FIG. Since the load torque curve A has a shape close to a sine wave, if the load torque curve can be approximated by a sine wave (sin θ), the curve in FIG. 15C approximating the curve C should have a cosine wave shape (= cos θ). Can do.

  The schematic configuration of the motor control device according to the present embodiment is the same as the schematic configuration of the motor control device according to the fourth embodiment of the present invention, and the operation of the motor drive voltage waveform correction unit 10 after the start of the synchronous motor 4 is completed. Since it may be the same as any one of the fourth to seventh embodiments of the present invention, the description thereof is omitted here.

<Compressor drive unit and refrigeration / air conditioner>
In a compressor used in a refrigeration / air conditioner, etc., the internal temperature becomes high, and it is difficult to provide a position sensor for detecting the rotor position such as a Hall IC. Therefore, it is necessary to drive a synchronous motor without a position sensor. is there. Therefore, the motor control device according to the present invention is used to drive the synchronous motor of the compressor driving device. As a result, a current sensor configured to detect an alternating current such as a current sensor constituted by a coil and a Hall element and a current transformer is not required, and a position sensor is also unnecessary. This means that even if it is a load element such as a compressor that does not have the above-mentioned sensor necessary for knowing the mechanical angle and the mechanical angle information such as the top dead center of the compressor is unknown. It can also be said that high-efficiency synchronous motor drive is enabled by connecting to the synchronous motor of the present invention and controlling with the motor control device according to the present invention.

  And the compressor drive device provided with this motor control apparatus which concerns on this invention is mounted in a refrigerating / air conditioning apparatus. This makes it possible to operate a refrigeration / air conditioning apparatus such as a refrigerator, a freezer, or an air conditioner. For example, in the case of an air conditioner, at least a compressor, an outdoor heat exchanger, an expansion device, and a refrigerant circuit in which an indoor heat exchanger is connected by a refrigerant pipe are provided, and the compressor driving device provided with the motor control device according to the present invention When the cooling operation is performed by switching the four-way valve, the flow direction of the refrigerant in the refrigerant circuit is as follows: compressor → outdoor heat exchanger → expansion device → indoor heat exchanger → compressor direction. When the operation is performed, the flow direction of the refrigerant in the refrigerant circuit is the direction of the compressor → the indoor heat exchanger → the expansion device → the outdoor heat exchanger → the compressor.

  The application of the motor control device according to the present invention is not limited to the motor drive of a compressor used in a refrigeration / air conditioning device or the like, but a synchronous motor that drives a load element with periodic load torque fluctuations The motor control device according to the present invention can be used for all variable speed control. By using the motor control device according to the present invention, highly efficient and stable driving can be realized.

<Summary>
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the same function as the microcomputer M1 may be realized by a plurality of microcomputers, and some or all of the functions of the microcomputer M1 may be realized by a dedicated electric circuit or the like. Moreover, you may make it implement combining several embodiment. For example, the second embodiment and the third embodiment can be implemented in combination.

  The motor control device described above is a device that controls a motor (4) that drives a load element having a periodic load torque fluctuation, and that detects a current amplitude that drives the motor (4) ( 6 and 7) and a correction unit (10) for correcting the motor drive voltage for driving the motor (4). The correction unit (10) includes all the motors corresponding to one cycle of the load element. A first electrical angle at which the motor drive current detected by the detection unit (6, 7) has a maximum peak is estimated from the electrical angle range, and the entire electrical angle range includes the first electrical angle. An electrical angle range is divided into an electrical angle range other than the one electrical angle range, and the first correction for reducing the motor drive voltage in the one electrical angle range is lower than that in the other electrical angle range. The configuration to be performed (first configuration) is assumed.

  According to such a configuration, the correction of reducing the motor drive voltage in the one electrical angle range than in the other electrical angle range suppresses the pulsation of the motor drive current, and the maximum value of the motor drive current is increased. Overcurrent can be suppressed. Further, in the other electrical angle range, the reduction in motor torque is suppressed, so that acceleration at a predetermined acceleration can be maintained.

  In the motor control device having the first configuration, the one electrical angle range includes an electrical angle at which the motor driving current is adjacent to at least one immediately before and immediately after the first electrical angle (second configuration). It is good also as a structure.

  According to such a configuration, even when the electrical angle at which the motor drive current reaches the maximum peak is different from the estimated first electrical angle, the pulsation of the motor drive current is suppressed with high accuracy, and the maximum motor drive current is obtained. It can suppress that a value becomes overcurrent.

  In the motor control device having the first or second configuration, the correction unit (10) corrects the motor drive voltage based on the motor drive current while the motor (4) accelerates after starting. It is good also as (3rd structure).

  According to such a configuration, it is possible to prevent the motor from stopping without being completed due to overcurrent.

  The motor control device having any one of the first to third configurations includes a voltage correction pattern storage unit (12) that stores a voltage correction pattern corresponding to one cycle of the load element, and the correction unit (10) includes: Two fluctuation amounts of the motor drive current when the motor is driven with the motor drive voltage corrected by the voltage correction pattern given a correction coefficient for shifting the phase of the voltage correction pattern by a predetermined angle. Based on the result compared with the set value of the correction coefficient, the second correction for determining the correction coefficient is performed, the second correction is performed after the first correction is canceled, and the second correction is performed. A configuration in which a set value of the correction coefficient is determined so that a maximum correction portion of the voltage correction pattern in the correction of 2 does not fall within the one electrical angle range divided by the first correction (fourth It may be formed).

  According to such a configuration, the correction coefficient can be set efficiently while suppressing the pulsation amount (variation amount) of the motor drive current waveform.

  In the motor control device of the fourth configuration, the correction coefficient includes a gain of the voltage correction pattern, and a result obtained by comparing a fluctuation amount of the motor drive current when the motor is driven with the gain set to a different value. As an index, the gain may be determined (fifth configuration).

  According to such a configuration, the pulsation amount of the motor drive current can be reduced (ideally zero) in response to the fluctuation of the load torque amount without the information on the fluctuation of the load torque amount. Can be driven with high efficiency.

  In the motor control device having the fourth or fifth configuration, the shape of the voltage correction pattern is obtained by subtracting a load torque value for each angle of the load element from an average value of the load torque for the one cycle of the load element. It is good also as a structure (6th structure) which is a shape based on the function which integrated the value with the angle of the said load element.

  According to such a configuration, the outline of the voltage correction pattern can be made similar to the exact outline of the speed variation pattern of the rotor of the motor, so that high accuracy of motor torque control can be expected.

  In the motor control device having any one of the fourth to sixth configurations, the shape of the voltage correction pattern is a measurement of an angular velocity change for one cycle of load torque fluctuation when the load element is rotated at a constant torque. However, a configuration based on the variation pattern (seventh configuration) may be employed.

  According to such a configuration, the correction pattern can be obtained without measuring the load torque curve, so that the voltage correction pattern can be easily defined.

  In the motor control device having the sixth or seventh configuration, the voltage correction pattern has a configuration in which the correction amount is smaller than that of the function or the variation pattern as a basis (eighth configuration). It is good.

  According to such a configuration, it is possible to prevent the voltage correction amount from being too large and the motor drive to become unstable, and in the worst case, the step-out can be prevented.

  The refrigeration / air conditioning apparatus described above is driven by the motor control apparatus having any one of the first to eighth configurations, the synchronous motor (4) driven by the motor control apparatus, and the synchronous motor (4). The configuration includes a compressor (the ninth configuration).

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter circuit 3 Inverter circuit 4 Synchronous motor 5 Current detection circuit 6 Motor drive current estimation part 7 Motor drive current memory | storage part 8 Rotation speed setting part 9 Motor drive voltage waveform creation part 10 Motor drive voltage waveform correction part 11 PWM waveform Creation unit 12 Voltage correction pattern storage unit M1 Microcomputer R1 Current detection resistor (shunt resistor)

Claims (4)

An apparatus for controlling a motor that drives a load element having periodic load torque fluctuations,
A detection unit for detecting an amplitude of a current for driving the motor;
A correction unit for correcting a motor driving voltage for driving the motor,
The correction unit is
When the number of rotations of the motor is a predetermined number of rotations, the amplitude of the motor drive current detected by the detection unit becomes a maximum value from the entire electrical angle range of the motor corresponding to one cycle of the load element. Estimate the electrical angle of 1,
When the motor from a state rotational speed of the motor is the predetermined rotational speed is accelerated, the total electric angle range, and one continuous electrical angle range including the front and rear of the first electrical angle, said The electric angle range is divided from the entire electric angle range to the other electric angle range excluding the one continuous electric angle range, and the motor driving voltage is reduced in the one continuous electric angle range as compared with the other electric angle range. A motor control apparatus that performs correction of 1. 2. The motor control according to claim 1, wherein the correction unit corrects a motor driving voltage based on the motor driving current after the motor is accelerated after starting and is shifted to a rotational speed feedback control. 3. apparatus. A voltage correction pattern storage unit for storing a voltage correction pattern corresponding to one cycle of the load element;
The correction unit is
Discretely changing the value of the correction coefficient after canceling the first correction,
Performing the first process and the second process for each value of the correction coefficient that is discretely changed;
The first process is a process of shifting the phase of the voltage correction pattern by an angle corresponding to the value of the correction coefficient by giving a correction coefficient to the voltage correction pattern.
In the second process, it is determined whether or not a maximum correction portion of the voltage correction pattern to which the correction coefficient is given is in the one continuous electrical angle range divided by the first correction. Processing,
Furthermore, the correction unit
The value of the correction coefficient that is discretely changed, and the maximum correction portion of the voltage correction pattern to which the correction coefficient is given is the one continuous electrical angle divided by the first correction. For each limit value that satisfies the condition that it does not fall within the range, the fluctuation amount of the motor drive current when the motor is driven with the motor drive voltage corrected by the voltage correction pattern given the correction coefficient is obtained. ,
Based on the obtained result, the correction coefficient is fixed to a specific value,
3. The second correction for correcting the motor drive voltage by the voltage correction pattern to which the correction coefficient is given in a state where the correction coefficient is fixed to the specific value. The motor control apparatus described. The motor control device according to any one of claims 1 to 3,
A synchronous motor driven by the motor control device;
And a compressor driven by the synchronous motor.

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