JP3696785B2 - Motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor control device, and more particularly to a motor control device that drives a motor used in an air conditioner compressor having a plurality of phase coils without a rotor position sensor.
[0002]
[Prior art]
In the motor driving method, the so-called 180-degree energization driving method does not provide an energization pause period in the motor coil current waveform in sensorless driving for controlling and driving the motor without using a motor rotor position sensor. It controls the phase difference of the motor coil current. In Japanese Patent Application No. 2000-044279 by the applicant of the present application, as an effective method for suppressing a decrease in phase difference information detection accuracy due to fluctuations in motor coil current, a sine wave can be used without providing a sensor such as a motor rotation detector. 180 degree energization driving including driving is possible, and improvement of motor efficiency, low noise and low vibration can be realized.
[0003]
FIG. 11 is a diagram showing a state of motor coil current sampling in this technique. In FIG. 11, the motor coil current is sampled a predetermined number of times at predetermined sampling timings sp0 to sp5 such that the sampling timings in both phase periods are symmetrical in two phase periods with reference to the motor drive voltage. The motor coil current values I0 to I5 in the period are integrated (S0, S1), and the ratio (S0 / S1) of the respective values is calculated and used as phase difference information. This phase difference information is predetermined. Control to be the value of.
[0004]
Since AD sampling is performed at a timing that is symmetric in the two phase periods, as shown in FIG. 11, when the phase difference between the voltage and the current is 0 degrees, the phase difference information is S0 = S1, so S0 / S1 = 1 is calculated. In order to control the phase difference at 0 degree, the phase difference information may be controlled to be 1.
[0005]
Some loads connected to the motor control device have a constant load torque (small load torque fluctuation), while many have a large load torque fluctuation. One example is a single rotary compressor or a rolling piston compressor (sometimes referred to as a rotary piston). The single rotary compressor or rolling piston compressor is widely used as a compressor for products such as air conditioners and refrigerators.
[0006]
In the following description, the failure of these compressors will be described simply as a single rotary compressor. The feature of the single rotary compressor is that it has a simple structure and is inexpensive to manufacture, but has a very large load torque fluctuation. In the single rotary compressor, the compression cycle of refrigerant suction, compression, and discharge is sequentially repeated during one rotation of the motor. Therefore, the refrigerant is compressed immediately before discharge and increases as the load torque, and immediately after discharge, the refrigerant is discharged and decreases as the load torque. Incidentally, such a load torque fluctuation does not occur in a scroll type compressor that continuously sucks, compresses and discharges refrigerant.
[0007]
FIG. 12 is a diagram showing load torque characteristics of a single rotary compressor and a scroll compressor. Moreover, as a method for correcting the load torque when connected to a load having a large load torque fluctuation such as a single rotary compressor, there is a technique described in Japanese Patent Publication No. 7-122439. In this prior art, load torque is calculated from a position signal of a rotational position sensor and output to a motor, and fluctuations in load torque are corrected to reduce vibration.
[0008]
[Problems to be solved by the invention]
In recent years, IPM (Interior Permanent Magnet) motors are increasingly used as compressor motors including air conditioners. In the case of a so-called IPM motor having a shape embedded in a permanent magnet rotor, such as a frequency value, a framing torque (sometimes referred to as magnet torque) generated as a magnetic flux and a coil current, and a motor coil depending on the rotor shape And the reluctance torque using the change in the inductance. Therefore, since a large torque can be obtained as compared with a synchronous motor using a normal permanent magnet, the motor can be highly efficient. The framing torque and the reluctance torque are functions of the relative position of the rotor and the stator, respectively. To maximize the sum of the framing torque and the reluctance torque, the motor coil at the appropriate rotor and stator relative position is used. It is known that the energization of is necessary. The following problems appear particularly prominently in this IPM motor, and characteristics such as motor efficiency thereafter use the IPM motor.
[0009]
As described in Japanese Patent Application No. 2000-044279, since the relative position of the rotor and the stator and the phase difference information have a linear relationship under the same rotation conditions, the rotor and the stator are indirectly controlled by phase difference control. That is, the energization timing of the relative position is controlled.
[0010]
When the motor drive based on the phase difference control described in Japanese Patent Application No. 2000-044279 described above is mounted on a motor having a large load torque variation such as a single rotary compressor, the following problems occur.
[0011]
FIG. 13 shows the phase difference information-efficiency characteristics, and the load torque fluctuation of the single rotary compressor is used as a parameter when the load torque is large and small. Here, it should be noted that when the load torque changes, the phase difference information differs even if the motor drive voltage is the same. For example, when the load torque is small in FIG. When the load torque is large, the motor is driven at a position where the phase difference information is different from that when the load torque is small. This is understood from the principle that a large motor drive voltage (≠ motor drive current) is required when the load torque is large. Therefore, if the load torque fluctuation is too large, the fluctuation cannot be dealt with and the motor-generated torque decreases, and the motor drive itself becomes impossible and stops. Hereinafter, this phenomenon is referred to as motor step-out. At this time, the phase difference information also fluctuates greatly and deviates from the motor drive possible phase difference information range.
[0012]
Incidentally, motor out-of-step occurs even when the motor drive voltage is too large relative to the load torque, but generally the margin is larger than when the motor drive voltage is too small, and many motor out-of-steps are caused by load torque. On the other hand, it often occurs when the motor generated torque is small, that is, when the motor drive voltage is small.
[0013]
As described above, the load torque fluctuation of the single rotary compressor is a sudden and large load torque fluctuation synchronized with one rotation of the motor, and this is difficult to follow in phase difference control due to the phase difference information detection cycle. This occurs because the motor drive voltage cannot be controlled / changed.
[0014]
Note that, when the load torque fluctuation period is very long, the change in efficiency peak phase difference information due to the magnitude of the load torque becomes large, but with a load torque fluctuation in a short period such as one motor rotation period as shown in FIG. Fits in a slight change. This is because fluctuations in a short cycle do not appear greatly in phase difference information fluctuations due to the influence of motor inertia and the like.
[0015]
Japanese Patent Publication No. 7-122439 obtains a load torque from a motor rotational position signal, but is not applicable to the phase difference control of Japanese Patent Application No. 2000-044279 that does not use a motor rotational position signal.
[0016]
Therefore, the main object of the present invention is to enable motor drive by 180 degree energization including sine wave energization that is low noise, low vibration, and high efficiency, and can be mounted in a wider range of equipment, reducing the cost, The object is to provide a motor control device capable of realizing high performance.
[0017]
[Means for Solving the Problems]
  This inventionA motor control device for driving a motor, wherein an inverter unit that converts a DC voltage into an AC voltage and applies the AC voltage to a motor coil, a coil current detection unit that detects a coil current of the motor,Multiple phase periods based on motor drive voltageDetected by the coil current detectorCoil powerFlowAccumulate and calculate the ratio of accumulated values in each phase period to detect phase difference informationAn error between the phase difference information detected by the phase difference detector detected by the phase difference detection unit, the target phase difference setting unit that sets the target phase difference information, and the target phase difference information set by the target phase difference setting unit. An arithmetic unit that outputs a control signal indicating;MotorIn one revolutionLoad torque fluctuationA load torque fluctuation detecting unit for detecting the load torque and a load torque fluctuation detecting unit for compensating for the fluctuation of the load torque detected by the load torque fluctuation detecting unit.Outputs load torque fluctuation correction signalAnd a control unit that controls the inverter based on the control signal and the load torque fluctuation correction signal.It is characterized by that.
[0018]
  Preferably, the phase difference detection unit isDetection of phase difference informationThe, Motor load torqueIs in one revolutionAverage valuePeriodwhilesoLineYeah.
[0019]
  Preferably, the phase difference detection unit isDetection of phase difference informationThe, Motor load torqueIs in one revolutionMaximum valuePeriodwhilesoLineYeah.
[0020]
  AlsoPreferably,The target phase difference setting unit is detected by the load torque fluctuation detection unit.MotorIn one revolutionAccording to load torque fluctuation,During one rotation of the motorTarget phase difference informationChangeThe Thereby, further improvement in motor efficiency can be realized.
[0021]
  AlsoPreferably, the load torque fluctuation detection unit is, Motor load torque fluctuationThe, Detected from phase difference information in each phase period during one rotation of the motorTheThereby, load torque fluctuation detection can be realized without an additional circuit and cost increase.
[0022]
  Preferably, the load torque fluctuation detecting unit is, Motor load torque fluctuationTheRefer to basic load torque fluctuation characteristics of motor loadinterpolationTo do. Thereby, more accurate load torque fluctuation can be realized.
[0024]
  AlsoPreferablyThe load of the motor has a load torque fluctuation in which the rotation of the motor is a basic cycle, including a single rotary compressor and a rolling piston compressor.The
[0025]
By using these configurations, the present invention performs motor drive by 180-degree energization including sine wave energization with low noise, low vibration, and high efficiency in a more precise configuration. Processing can be realized at low cost. In addition, the cost of the entire apparatus can be reduced, and a mechanism that is not affected by fluctuations in the motor load torque can be selected, and the degree of freedom in design can be expanded.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In FIG. 1, the motor 1 is driven by an inverter circuit 2. The inverter circuit 2 is supplied with the AC voltage from the AC power source 4 converted into a DC voltage by the converter circuit 3. A current sensor 5 is provided for detecting a motor coil current flowing in a specific phase (the U phase in FIG. 1) among the phases of the coil terminals U, V, and W of the motor 1. The motor coil current detected by the current sensor 5 is supplied to a motor current detection amplifier unit 6, and a predetermined amount of amplification and offset addition are performed, and a motor coil current signal is supplied to a microcomputer 7 as a control device.
[0027]
The microcomputer 7 includes a phase difference detection unit 8, a target phase difference information storage unit 9, an adder 10, a PI calculation unit 11, a rotation speed setting unit 12, a sine wave data table 13, a sine wave data creation unit 14, and a PWM creation unit 15. The load torque fluctuation detecting unit 16, the load torque fluctuation correcting unit 17, and the adder 18 are included, and each process is performed in software.
[0028]
That is, the phase difference detection unit 8 adds the motor coil current detection values for the two motor drive voltages for each phase period to obtain the motor coil current signal area, and the area ratio of both motor coil current signal areas as the phase difference information. To detect. The target phase difference information storage unit 9 stores target phase difference information, and the adder 10 calculates error data between the target phase difference information and the phase difference information output from the phase difference detection unit 8, and the calculation is performed. The result is given to the PI calculation unit 11. The PI calculation unit 11 calculates proportional error data (P) and integral error data (I) with respect to the calculated error data, and outputs a PI control signal to the adder 18.
[0029]
The load torque fluctuation detection unit 16 detects the load torque applied to the motor 1 and the load torque fluctuation, and supplies the detected output to the load torque fluctuation correction unit 17. The load torque fluctuation correction unit 17 creates a load torque fluctuation correction signal for correcting and removing the detected load torque fluctuation, and outputs the load torque fluctuation correction signal to the adder 18. The adder 18 adds the PI control signal from the PI calculation unit 11 and the load torque fluctuation correction signal from the load torque fluctuation correction unit 17, and outputs a duty reference value to the PWM creation unit 15.
[0030]
The rotation speed setting unit 12 sets a rotation speed command of the motor 1 and the sine wave data table 13 outputs sine wave data composed of a predetermined number of data. The sine wave data creation unit 14 reads out the sine wave data corresponding to the phases of the motor coil terminals U, V, and W from the sine wave data table 13 according to the passage of time and the rotation speed command set by the rotation speed setting unit 12. While outputting to the PWM production | generation part 15, the U phase motor drive voltage phase information is output to the phase difference detection part 8 from U phase sine wave data. The PWM generator 15 outputs a PWM waveform signal, which is a motor drive voltage, to each drive element of the inverter circuit 2 for each phase from the sine wave data and the duty reference value.
[0031]
The current sensor 5 may be a so-called current sensor or a current transformer composed of a coil and a Hall element. Further, when the motor coil current of each phase as well as one phase is detected, higher accuracy is obtained. Furthermore, the sine wave data may be created by calculation without being created based on the sine wave data table 13.
[0032]
The drive waveform of the motor 1 shown in FIG. 1 shows a configuration in the case of a sine wave. However, since a smooth motor coil current can be supplied by using a sine wave, vibration and noise are reduced. it can. However, the present invention is not limited to this, and driving with higher efficiency is possible if a drive waveform that provides a motor coil current that matches the magnetic flux distribution of the motor rotor is applied.
[0033]
The area ratio of the two motor coil current signal areas in which the two motor drive voltages are detected in the phase period is calculated by the phase difference detection unit 8, and this result is used as phase difference information. An error amount between the phase difference information and the target phase difference information is obtained by the adder 10, PI calculation is performed by the PI calculation unit 11, and the PI control signal, load torque fluctuation correction signal, and the adder 18 add the output. The PWM generator 15 calculates the output duty for each output duty reference value and sine wave data separately obtained from the rotation command, and applies it to the motor coil via the inverter 2 to drive the motor 1. The
[0034]
That is, the magnitude of the drive voltage (duty width of the PWM duty) is determined by the phase difference control feedback loop for controlling the motor coil current phase difference with respect to the motor drive voltage (output duty) to be constant. In order to rotate at the rotational speed, the rotational speed is determined by sine wave data output at a desired frequency, and the motor 1 is driven and controlled with a desired phase difference and a desired rotational speed.
[0035]
Next, setting of the rotation speed and PWM output will be described. In the phase difference control system according to the present invention, the speed of the motor is determined by the frequency of a sine wave voltage composed of a PWM wave that is energized to the motor coil, unlike the system that performs speed control by detecting a counter electromotive voltage pulse or the like. This is so-called forced excitation drive.
[0036]
The sine wave data table 13 stores a data string in which a sine wave waveform is output when analog values are continuously output, and the reference address of this data string is updated by a predetermined number for each PWM carrier period. If this predetermined number is large, the rotation speed is high. That is, the motor rotation speed is determined by the update interval between the PWM carrier frequency and the reference data in the sine wave data table 13 except for the structural one of the motor 1. For example, if the number of coil phases is 3, the data of each phase may be referred to sine wave data shifted by 120 degrees in electrical angle. Note that sine wave data may be generated by performing sine wave calculation each time.
[0037]
Incidentally, the reference address is the phase information itself of the motor drive voltage. The obtained sine wave data for each phase is multiplied by the duty reference value calculated by the phase difference control, and is input to the PWM generator 15 such as a so-called PWM waveform generator to output a PWM waveform signal. The outline of this PWM waveform generator is, for example, generating a triangular wave at a PWM carrier cycle, comparing the peak value of this triangular wave with the multiplied value, and outputting High / Low based on the comparison result.
[0038]
Next, a method for detecting phase difference information will be described. As shown in FIG. 11, the motor voltage phase θ0 in the first phase period in the motor voltage phase is 0 to 90 degrees, and the second phase period θ1 is 90 to 180 degrees. Each sampling timing is set to be sampled n times (three times in the case of FIG. 11, a total of 6 times) at equal phase intervals of ts. The phase difference information is obtained by integrating I0 + I1 + I2 with the motor coil current signal area at θ0 as S0, integrating I3 + I4 + I5 with the motor coil current signal area at θ1 as S1, and the ratio of the two motor coil current signal areas (S0). / S1) is calculated. In the case of FIG. 11, the phase difference information is 1.
[0039]
As described above, the sampling timing in each phase period can be symmetric with respect to the motor voltage phase of 90 degrees, so that control design such as setting of the target phase difference is facilitated.
[0040]
Here, the case where a load having a large load fluctuation during motor rotation as shown in the load torque characteristic of the single rotary compressor of FIG. 12 including the single rotary compressor as described above is connected as the load of the motor 1 will be described. To do. In the phase difference control from the phase difference detection cycle or the like, it is difficult to control following such a large and rapid load torque fluctuation. Therefore, the measures described later are required.
[0041]
FIG. 2 is a diagram showing characteristics of motor efficiency, phase difference information, and motor drive voltage. In FIG. 2, each load torque indicates when the load torque fluctuation of the single rotary compressor is large and small, (a) indicates a small load torque, and (b) indicates a large load torque. As specified in the above-mentioned Japanese Patent Application No. 2000-144279, there is a linear relationship between the motor drive voltage and the phase difference information. Therefore, phase difference information = K1 × motor drive voltage + K2 (K1 and K2 are phase relationships). Number). The correlation coefficients K1 and K2 vary depending on the rotation conditions including the load torque.
[0042]
FIG. 3 is a diagram showing phase difference information-motor drive voltage characteristics in the first embodiment of the present invention. As shown in FIG. 3, a large motor drive voltage (≠ motor drive current) is required when the load torque is large, and a small motor drive voltage (≠ motor drive current) is sufficient when the load torque is small.
[0043]
In FIG. 2, the characteristics of FIG. 3 are taken into consideration, and the horizontal axis represents not only the phase difference information but also the motor drive voltage. For this reason, the scale of the motor drive voltage axis differs between the small load torque shown in FIG. 2A and the large load torque shown in FIG.
[0044]
In order to drive the motor with high efficiency as described above from the motor efficiency characteristics, or to maintain the motor rotation without causing the motor step-out, the energization timing to the relative position of the rotor and the stator is controlled to an appropriate value. In other words, it is necessary to control the phase difference information to an appropriate value. This indicates that it is necessary to perform control within the motor-driveable phase difference information range of each characteristic in FIG.
[0045]
For this purpose, it is necessary to output an appropriate value as the motor drive voltage. As shown in FIG. 2, changing the motor drive voltage means changing the phase difference information. If the motor drive voltage is too small, the motor generated torque that drives the load torque cannot be output, and the motor step-out may occur. Will occur. Referring to FIG. 2, the motor drive voltage Vs can be driven with high efficiency when the load torque is small, but the motor step-out occurs when the load torque is large. On the other hand, even if the motor drive voltage is excessive, it becomes vibrational due to the excessively generated torque, and eventually the motor steps out. However, the margin is generally larger than when it is excessively small.
[0046]
In the present invention, the load torque fluctuation detection unit 16 detects the load fluctuation during the rotation of the motor, and the load torque fluctuation correction unit 17 creates a load torque fluctuation correction signal so that the motor efficiency does not decrease or the motor step-out does not occur. The adder 8 adds the load torque fluctuation correction signal and the PI control signal in the phase difference control to output a motor drive voltage.
[0047]
The load torque fluctuation correction signal is added every time the phase difference information is detected, and during that time, the same duty reference value may be held, or the addition by the adder 18 is executed every PWM carrier period. If the duty reference value is created by updating the load torque fluctuation correction signal each time, a more accurate load torque fluctuation correction signal can be output, and the correction effect is enhanced. This makes it possible to achieve control that maintains motor drive without causing motor step-out and does not reduce motor efficiency even under a load environment of sudden and large load torque fluctuation that is difficult to follow in phase difference control. . Therefore, the effects of high efficiency, low vibration, and low noise of 180 degree energization driving including sine wave driving in phase difference control can be inherited.
[0048]
In the above description, the load torque fluctuation correction signal is added. However, the present invention is not limited to this. A load torque fluctuation correction signal is created as the gain of the PI control signal, and the load torque fluctuation correction signal is multiplied by the PI control signal. It may be configured to match.
[0049]
Here, depending on the use situation of the motor, it is not necessary to be particularly concerned with the efficiency, and it is only necessary to keep the motor rotating without causing the motor step-out, or the decrease in efficiency due to load torque fluctuation does not fall below the use. In such a case, the correction by the load torque fluctuation correction unit 17 as described above is not particularly necessary.
[0050]
FIG. 4 is a diagram illustrating an example of a load torque fluctuation during one rotation of the motor and a phase period of phase difference information detection. In FIG. 4, the phase period is the total phase period that is the sum of the two phase periods. As described above, motor out-of-step occurs frequently when the motor generated torque is small relative to the load torque, that is, when the motor drive voltage is small. Therefore, if the phase difference information is detected and controlled in the phase period θ2 where the load torque is maximum, the motor generated torque does not fall below the load torque, and motor step-out can be suppressed.
[0051]
As shown in FIG. 2, Vb is set so that the motor driving voltage has the highest efficiency by controlling the phase difference when the load torque is large. Even when the load torque is small, Vb remains, so the maximum efficiency cannot be obtained when the load torque is small. However, the motor drive can be continued because it is not in the phase difference information range and motor drive voltage range where the motor steps out.
[0052]
Alternatively, the phase period during which the phase difference information is detected may be set at a position where the load torque during one rotation of the motor is average. For example, in FIG. 3, a value obtained by averaging the phase difference information at θ0 to θ3 may be used, or the phase difference information of the maximum and minimum phase periods θ0 and θ2 may be averaged or averaged. The phase difference information in the phase period of θ1 or θ3 in which a typical load torque is generated may be used.
[0053]
In this case, the motor generated torque is less than the maximum load torque. However, as shown in FIG. 2, the motor drive voltage Va that is an average of the load torques is output. There is little occurrence of tone, and the motor drive is continued. Further, when the motor rotation speed becomes high, the motor 1 rotates by inertia due to the increase of the motor energy, so that the motor step-out due to the motor generated torque being too small can be suppressed. Therefore, the motor drive at the maximum efficiency at each load torque cannot be realized, but an average efficiency can be obtained by looking at one rotation of the motor. Further, since the phase difference information and motor drive voltage at which the motor 1 steps out at each load torque are not obtained, the motor drive can be continued.
[0054]
FIG. 5 is a block diagram showing a configuration of the second embodiment for setting a detection phase period of phase difference information. In FIG. 5, the load torque fluctuation information detected by the load torque fluctuation detection unit 16 is given to the phase difference detection unit 8a, and the phase difference detection unit 8a drives the motor to detect the above phase difference information from the load torque fluctuation information. The voltage phase period is determined and phase difference information is detected. The rest is the same as the configuration of FIG.
[0055]
In this way, the effect of low vibration and low noise of 180-degree energization drive including sine wave drive by phase difference control can be inherited without causing motor step-out by a simple method.
[0056]
Here, it has been explained that tracking with phase difference control is difficult because the load torque including a single rotary compressor is sudden and large, but in order to control the motor efficiency as close to the maximum efficiency as possible. It is desirable to change the target phase difference information according to the load torque fluctuation, not only in the correction by the load torque fluctuation correction signal but also in the phase difference control.
[0057]
This setting is for setting the target phase difference information for the phase period in accordance with the load torque for each phase period in FIG. 4. For example, when the load torque is small in FIG. 2, the target phase difference information is set to βs. When the torque is large, the target phase difference information is set to βb each time. As a result, it is possible to inherit the effects of low vibration and low noise of 180-degree energization drive including sine wave drive by phase difference control without causing motor step-out with respect to load torque fluctuation during one rotation of the motor, Further high efficiency drive can be realized.
[0058]
Next, an example of a load torque fluctuation detection method in the load torque fluctuation detection unit 16 will be described. The detection method of the load torque fluctuation in this embodiment detects from the phase difference information used in the phase difference control, and pays attention to the fact that the phase difference information fluctuates due to the load torque fluctuation.
[0059]
This detects load torque fluctuation from phase difference information fluctuation during one rotation of the motor when the motor drive voltage is constant. In FIG. 2, when the motor driving voltage is Va, the phase difference information when the load torque is small is βa, but the phase difference information when the load torque is large is βa ′. The load torque is detected from the change in the phase difference information. Phase difference information is detected in each phase period, a load torque phase difference during motor rotation is detected from the fluctuation, and a load torque fluctuation value is detected from the magnitude of the fluctuation of the phase difference information.
[0060]
FIG. 6 is a diagram showing a load torque fluctuation waveform of a single rotary compressor and the accompanying phase difference information fluctuation. As shown in FIG. 6, it can be seen that there is a correlation between the load torque fluctuation and the phase difference information, and the load torque fluctuation can be detected from the phase difference information. Since the phase difference information is detected for each phase period, the detection resolution is often coarser than that in FIG. 6, and the load torque fluctuation detection accuracy is thereby lowered, but if it can be detected to some extent, the correction is realized. The detection resolution of the phase difference information may be set in accordance with the load torque detection accuracy. Alternatively, a case where high-precision detection is required while having a coarse detection cycle can be solved by a method described later.
[0061]
In addition, although the fluctuation | variation of phase difference information is reversed in waveform with the load torque fluctuation waveform, it may be reversed and used.
[0062]
FIG. 8 is a block diagram showing the configuration of the third embodiment of the present invention. In FIG. 8, the phase difference information output from the phase difference detection unit 8 is input to the load torque fluctuation detection unit 16, and the load torque fluctuation detection unit 16 detects the fluctuation of the load torque from the fluctuation of the phase difference information. As the fluctuation detection, the correlation between the fluctuation of the phase difference information and the load torque fluctuation as shown in FIG. 6 is stored as data, and the load torque fluctuation may be detected from the fluctuation width of the actual phase difference information. Other methods may be used. The rest of the configuration is the same as in FIG.
[0063]
Normally, loads with load fluctuations synchronized with one rotation of the motor, such as a single rotary compressor, often have a constant load torque fluctuation waveform and phase. Therefore, once the load torque is detected, subsequent detection is possible. Is not necessary. However, in some cases, the load torque fluctuation waveform and phase change depending on the motor rotation speed and the average load. With such a load, the load torque fluctuation detection process described above may be performed every predetermined time or whenever the motor rotation is changed.
[0064]
Using the fact that the load torque fluctuation waveform is substantially constant, load torque fluctuation detection with higher accuracy can be realized. FIG. 7 is a diagram showing a load torque fluctuation-phase difference information waveform. As shown in FIG. 7, if the phase difference information detection interval, that is, the load torque variation detection is performed when the phase difference information detection interval, that is, the load torque variation detection cycle is rough with respect to the original load torque variation waveform, an accurate load is detected. Torque fluctuation is difficult to obtain, and load torque fluctuation can be detected to some extent, but high accuracy cannot be realized.
[0065]
Here, if the original basic load torque fluctuation waveform is stored and processed so as to interpolate the detected load torque fluctuation, the load torque fluctuation can be detected with higher accuracy.
[0066]
In the case of FIG. 7, the phase difference information is detected four times during one rotation of the motor, that is, the load torque fluctuation is detected. The load torque fluctuation can still be detected from now on, but if the correspondence between the phase and magnitude of the original load torque fluctuation waveform is detected from the magnitude relationship of the phase difference information, and interpolation is performed, a more accurate load torque fluctuation can be obtained. It can be detected. This interpolated waveform is also shown in FIG.
[0067]
The load torque fluctuation waveform to be stored is determined from the allowable value of the phase difference information fluctuation in the load torque fluctuation, and the load torque fluctuation waveform may be stored as a data string with a corresponding resolution, or a sine wave or the like If approximation can be performed with a simple mathematical expression, the mathematical expression may be stored.
[0068]
As described above, the present invention detects load torque fluctuations from phase difference information that is normally used for motor drive, and does not require a special load circuit. An invention for load torque fluctuation can be realized.
[0069]
The following method is also effective for periodic load torque fluctuations.
FIG. 9 is a block diagram showing the configuration of the fourth embodiment of the present invention. In FIG. 9, the PI control signal obtained by the phase difference control is repeatedly input to the compensation unit 19. Then, the adder 20 adds the PI control signal and the compensation signal output from the repetitive compensation unit 19. The rest of the configuration is the same as in FIG.
[0070]
FIG. 10 is a block diagram showing the configuration of the iterative compensation unit. The phase period for detecting the phase difference during one rotation of the motor is set to four times (θ0 to θ3) as shown in FIG. First, stored data is read from the address (θ0 to θ3) of the storage unit 192 corresponding to the current phase period (θ0 to θ3), multiplied by a predetermined gain G by the gain unit 193, and the compensation signal is sent to the adder 20. Is output. The PI control signal is integrated with past storage data of the same phase period as the current phase period (θ0 to θ3) stored in the storage unit 192 by the integration unit 191, and again the corresponding address (θ0 to θ3) of the storage unit 192 is obtained. ).
[0071]
Here, the gain unit 193 is adjusted to a value that does not cause the control system to oscillate, and it is desirable to measure and set the control characteristics.
[0072]
The integration of the PI control signal in each phase period may be performed by integrating all past signals. However, when the load torque fluctuation may be gradually changed, the past number of integrations may be used. Alternatively, the past PI control signal may be used without integration.
[0073]
As described above, since the load torque fluctuation is periodic with one rotation of the motor, it can be efficiently controlled by referring to the previous phase difference information.
[0074]
As described above, according to the embodiment of the present invention, it is possible to effectively correct a load having a periodic load torque fluctuation and to realize efficient motor driving without motor step-out. Furthermore, since all can be realized by software processing, there is no increase in cost.
[0075]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0076]
【The invention's effect】
As described above, according to the present invention, it is possible to drive a load having a sudden and large load torque fluctuation such as a single rotary compressor without causing motor step-out. Therefore, it is possible to mount a motor drive by 180 degree energization including sine wave energization which is low noise, low vibration and high efficiency in a wider range of fields, and to realize low cost and high performance. In other words, even in applications where a single rotary compressor or the like could not be used due to the effects of motor efficiency, noise, and vibration, the present invention can be used, so that the cost of the entire apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a diagram showing phase difference information, motor drive voltage-motor efficiency characteristics in the first embodiment of the present invention.
FIG. 3 is a diagram showing phase difference information-motor drive voltage characteristics according to an embodiment of the present invention.
FIG. 4 is a diagram showing a load torque fluctuation waveform in the first embodiment of the present invention.
FIG. 5 is a block diagram showing a second embodiment of the present invention.
FIG. 6 is a diagram showing a load torque fluctuation and phase difference information waveform according to a second embodiment of the present invention.
FIG. 7 is a diagram showing load torque fluctuation and phase difference information waveforms.
FIG. 8 is a block diagram showing a third embodiment of the present invention.
FIG. 9 is a block diagram showing a fourth embodiment of the present invention.
10 is a block diagram of a repetitive compensation unit included in the embodiment shown in FIG. 9;
FIG. 11 is a motor coil current waveform and a sampling timing diagram.
FIG. 12 is a diagram showing a load torque fluctuation waveform.
FIG. 13 is a diagram showing phase difference information-motor efficiency characteristics.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Motor, 2 Inverter circuit, 3 Converter circuit, 4 AC power supply, 5 Current sensor, 6 Motor current detection amplifier part, 7 Control microcomputer, 8, 8a Phase difference detection part, 9 Target phase difference information storage part, 10, 18, 20 Adder, 11 PI calculation unit, 12 Rotation speed setting unit, 13 Sine wave data table, 14 Sine wave data creation unit, 15 PWM creation unit, 16 Load torque fluctuation detection unit, 17 Load torque fluctuation correction unit, 19 Repetition compensation unit, 191 integration unit, 192 storage unit, 193 gain unit.

Claims (7)

A motor control device for driving a motor,
An inverter unit that converts a DC voltage into an AC voltage and applies it to the motor coil;
A coil current detector for detecting the coil current of the motor;
The coil current detected by the coil current detection unit integrates a plurality of phase periods relative to the motor drive voltage, the phase difference detecting section for detecting a phase difference information by calculating the ratio of the integrated values in each phase period ,
Target phase difference setting unit for setting target phase difference information;
A calculation unit that outputs a control signal indicating an error between the target phase difference information set by the target phase difference setting unit and the phase difference information detected by the phase difference detection unit;
A load torque fluctuation detector for detecting fluctuations in load torque during one rotation of the motor ;
A correction unit that outputs a load torque fluctuation correction signal for compensating for fluctuations in the load torque detected by the load torque fluctuation detection unit; and
Characterized Rukoto a control unit for controlling the inverter based on the control signal and the load torque variation correction signal, the motor control device. The phase difference detection unit, the detection of the phase difference information, the load torque of the motor is characterized by performing between the average value and Do that period in one rotation, the motor control device according to claim 1. The phase difference detection unit, the detection of the phase difference information, the load torque of the motor and performing between the maximum value and Do that period in one rotation, the motor control device according to claim 1. The target phase difference setting unit, according to the load torque variation in one rotation of the motor detected by the load torque fluctuation detecting unit, and wherein Rukoto varying the target phase difference information in the motor 1 in rotation The motor control device according to any one of claims 1 to 3. The load torque fluctuation detection unit detects the load torque fluctuation of the motor from the phase difference information in each phase period during one rotation of the motor. Motor control device. The motor control device according to claim 5, wherein the load torque fluctuation detection unit interpolates the load torque fluctuation of the motor with reference to a basic load torque fluctuation characteristic of the motor load. The motor control according to any one of claims 1 to 6 , wherein the load of the motor has a load torque fluctuation in which one rotation of the motor including a single rotary compressor and a rolling piston compressor is a basic cycle. apparatus.

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