JPH11187692A - Motor load torque unevenness reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide with a simple construction a motor load torque unevenness reduction device with which the load torque unevenness of a motor can be reduced. SOLUTION: When a compressor 46 is driven by a brushless motor 21, the zero-cross points of induced voltages induced in a motor 21 are detected by comparators 37, 38 and 39 and a motor control unit 41 to output position detection signals DSU, DSV and DSW. A PWM pattern determination unit 43 determines the position of a rotor, at which the output intervals of the position detection signals DSU, DSV and DSW which are measured by a signal interval measurement unit 44 are maximum as a reference position. Then a PWM signal pattern in accordance with the negative-phase sequence pattern of the fluctuation pattern of the load torque of the motor 21 which is measured beforehand is read from a memory unit 43a with the reference position as a trigger and outputted to a driving circuit 3 via the motor control unit 41 to control the driving of the motor 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing load torque unevenness of a motor for driving a load that causes torque unevenness in structure.

[0002]

For example, as a motor for driving a compressor of a refrigerator or an air conditioner, in a case where it is necessary to vary the capacity of the compressor, a brushless DC motor is used because of its easy rotation speed control. Permanent magnet type motors such as motors have been adopted.

Recently, low noise and low vibration are required for products such as the refrigerator and the air conditioner. However, since the compressor operates by repeating a cycle consisting of compression and expansion, torque unevenness, which is one cycle for one rotation of the motor, is inevitably generated during driving. Such torque unevenness causes speed unevenness, and eventually causes noise and vibration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an apparatus for reducing uneven load torque of a motor which can reduce uneven load torque of the motor with a simple configuration.

[0005]

According to a first aspect of the present invention, there is provided an apparatus for reducing load torque unevenness of a motor, comprising detecting a rotor position of a motor driven by a driving unit at predetermined electrical angles. Rotor position detecting means for outputting a detection signal, measuring means for measuring an output interval of the position detection signal outputted from the rotor position detecting means, and a reverse phase pattern of a previously measured fluctuation pattern of the load torque of the motor. Storage means for storing an energization signal level pattern based on the rotor position, wherein the rotor position at which the output interval measured by the measurement means is a minimum value or a maximum value is determined as a reference position, and the storage is performed based on the reference position. Control means for controlling the drive of the electric motor by reading out the energization signal level pattern stored in the means and outputting it to the drive means. And wherein the door.

With such a configuration, the control means determines the rotor position at which the output interval of the position detection signal measured by the measuring means is a minimum value or a maximum value as a reference position. Then, the control means drives the motor by reading out the energization signal level pattern based on the reverse phase pattern of the fluctuation pattern of the load torque of the motor measured in advance from the storage means based on the reference position and outputting it to the drive means. Control. Then, the motor is driven by an energization signal based on the reverse phase pattern of the variation pattern of the load torque, and acts so as to cancel the unevenness of the load torque. Therefore, the load torque unevenness of the motor can be reduced with a simple configuration.

In this case, it is preferable that the rotor position detecting means is configured to detect the rotor position by a magnetic detecting element arranged on the rotor. The position can be easily detected by the change in magnetism caused by the rotation of the rotor.

Further, it is preferable that the rotor position detecting means is configured to detect the rotor position by detecting a zero cross point of an induced voltage generated in a winding of the motor. With this configuration, the rotation position of the rotor can be detected based on the zero-cross point of the induced voltage, even in the case of a sensorless drive system that drives a motor without using a position sensor or the like.

[0009] As described in claim 4, the control means includes:
When the number of rotations of the motor reaches a predetermined value, the reference position of the rotor may be determined based on the result of averaging each output interval of the position detection signal measured by the measuring means during that time. With such a configuration, for example, even if the position detection error of the rotor that occurs when performing the PWM control has a magnitude that cannot be ignored compared to the fluctuation of the rotation speed of the motor, each output interval of the position detection signal is individually set. By averaging, the influence of the PWM control can be reduced.

[0010] As described in claim 5, the control means comprises:
It is preferable that the reference position is determined only once after the motor is started. With such a configuration, unnecessary determination processing is not performed.

According to a sixth aspect of the present invention, a plurality of energization signal level patterns are stored in the storage means in accordance with a plurality of load torque fluctuation patterns measured in advance for different driving states depending on the load. It is preferable that the state of the load is estimated from the rotation speed of the motor and the energization signal, and one of the plurality of energization signal level patterns is selected based on the estimation result and read out from the storage means.

[0012] With this configuration, for example, if the load torque is known to change according to the number of rotations of the motor or the like depending on the type of load or the like, the load torque varies according to the different load torque fluctuation patterns. A plurality of energization signal level patterns are stored in the storage unit, and the control unit estimates one of the plurality of patterns based on a result of estimating a load state from the motor rotation speed and the energization signal when the motor is actually driven. Is selected and output to the driving means, the load torque unevenness of the motor which varies depending on the driving state of the load can be reduced.

[0013] As described in claim 7, in the storage means,
Stores a plurality of energization signal level patterns with different phases,
The control means selects one of a plurality of energization signal level patterns having different phases from the storage means according to the position where the reference position of the rotor is detected by the rotor position detection means and reads it from the storage means. It is good also as composition which puts out.

For example, when the motor has four or more poles and the electric angle period for one rotation of the motor is two or more, the reference position of the rotor must be at a different rotor position according to the setting of the origin. become. Therefore, with this configuration, it is possible to output an energization signal level pattern having a correct phase according to the electrical angle to the driving unit.

In the above case, as described in claim 8, it is preferable that the load is a compressor. With such a configuration, when the compressor is driven by the motor, the compression-expansion cycle is increased. It is possible to reduce the inevitable load torque unevenness.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a brushless motor driven by using a compressor used in a refrigerator as a load will be described below with reference to the drawings. The DC power supply 1 is obtained by rectifying a commercial AC power supply with a rectifier circuit (not shown). The positive and negative terminals of the DC power supply 1 are connected to a drive circuit (driving means) via a current detection resistor 2 on the negative terminal side. 3 are connected to input terminals 4 and 5, respectively. Incidentally, the negative terminal of the DC power supply 1 is grounded.

The driving circuit 3 has an NPN circuit between the input terminals 4 and 5.
Transistors 6 to 8 and 9 to 11 are connected in a three-phase bridge connection. The transistors 6 to 1
1, diodes 12 to 17 are connected in parallel. The common connection point of the transistors 6 and 9 is connected to the output terminal 18, the common connection point of the transistors 7 and 10 is connected to the output terminal 19, and the common connection point of the transistors 8 and 11 is connected to the output terminal 20. I have.

3 for driving the compressor 46 as a load
4-phase brushless motor (hereinafter simply referred to as motor)
21 is a U-, V- and W-phase stator (stator) winding 22
A stator 22 having U, 22V and 22W, and a permanent magnet type rotor (rotor, not shown) are provided. One terminal of the stator windings 22U, 22V and 22W is connected in common, and the other terminal is connected to the output terminal 18 of the drive circuit 3,
19 and 20 are respectively connected.

The voltage dividing circuit 23 is composed of voltage dividing resistors 24 to 29, and one terminal of each of the stator windings 22U, 22V and 22W, that is, the output terminals 18, 19 and 20 of the driving circuit 3 and the ground ( A series circuit of voltage-dividing resistors 24 and 25, a series circuit of voltage-dividing resistors 26 and 27, and a series circuit of voltage-dividing resistors 28 and 29 are provided between the input terminal 5) and the ground terminal of the drive circuit 3. It is connected. And the voltage dividing resistor 2
4 and 25, voltage dividing resistors 26 and 27 and voltage dividing resistors 28 and 29
Are connected to the detection terminals 30, 31, and 32, respectively.

The reference voltage generating circuit 33 includes a voltage dividing resistor 34.
And 35, which are connected between the positive terminal and the negative terminal of the DC power supply 1. The common connection point of the resistors 34 and 35 is used as a reference terminal 36.
Incidentally, the resistance value ratio between the voltage dividing resistors 24, 26 and 28 of the voltage dividing circuit 23 and the voltage dividing resistors 25, 27 and 29 is K to 2 (however,
K is a natural number), and the resistance value ratio between the resistors 34 and 35 of the reference voltage generating circuit 33 is set to (K + 1): 1.

The non-inverting input terminals (+) of the three comparators 37, 38 and 39 are connected to the detecting terminals 30, 31 and 32, respectively. The terminal 36 is connected to the reference voltage VR (= E /
2) is given.

The control section 40 is mainly composed of a microcomputer, and when functionally shown in a block diagram, a motor control section 41, a voltage command signal generation section 42, a PW
It comprises an M pattern determining section 43, an enable signal generating section 44, and a signal interval measuring section (measuring means) 45.

The three input ports of the motor control section 41 are supplied with zero-cross point detection signals DSU ', DSV' and DSW 'from output terminals of comparators 37 to 39, respectively. PW to one input port
A PWM signal and an enable signal SE are supplied from output terminals of the M pattern determination unit 43 and the enable signal generation unit 44.

The motor control section 41 outputs a base signal (energization signal) to the bases of the transistors 6 to 11, respectively. Further, the motor control unit 41 outputs the speed detection signal DV to the input terminal of the voltage command signal generation unit 42, and sends the zero cross point detection signals DSU 'and DSV' to the PWM pattern determination unit 43 and the signal interval measurement unit 45.
And DSW 'are shaped into a position detection signal DS.
U, DSV and DSW are output. Incidentally, the comparators 37, 38 and 39 and the motor control section 41 correspond to a rotor position detecting means.

The voltage command signal generator 42 is supplied with a speed command signal SV from a microcomputer (not shown) which controls the cooling of the refrigerator itself. Further, the voltage command signal generating section 42 outputs a voltage command signal to the PWM pattern determining section 43. Then, the PWM pattern determination unit 43 sequentially outputs the duty value of the PWM signal to the motor control unit 41 and the enable signal generation unit 44. Further, the PWM pattern determination unit 43 has a built-in storage unit (storage means) 43a in which a plurality of PWM signal patterns (energization signal level patterns) are stored.

The PWM pattern determining section 43 receives a P.C. from a microcomputer for controlling the cooling of the refrigerator described above.
Duty information relating to the WM signal is provided, and a time measurement signal Tn is provided from the signal interval measurement unit 45.

Next, the operation of the present embodiment will be described with reference to FIGS. The basic drive control of the motor 21 is described in, for example, Japanese Patent Application No. 3-249228.
This is a well-known technology as disclosed in Japanese Patent Application Laid-Open No. H10-209, etc., and portions other than those relating to the gist of the present invention will be schematically described.

During the rotation of the motor 21, the terminal voltages UV of the stator windings (windings) 22U, 22V and 22W,
The induced voltages appearing as VV and WV are divided by the voltage dividing circuit 23 and detected as detection voltages UVa, VVa and WVa (see FIGS. 2 (a), (b) and (c)). Reference voltage generation circuit 3
3 is compared with a reference voltage VR given by the terminal voltage UV, VV and WV.
DSV 'and DSW' (not shown) are output.

Incidentally, the waveforms of the actual terminal voltages UV, VV and WV are output in a pulse form by PWM control (see FIG. 4), and therefore, the zero-cross point detection signal DS
The high-level portions of U ', DSV' and DSW 'have a pulse-like waveform. These zero-crossing point detection signals DSU ', DSV' and DSW 'are shaped into rectangular waves by the motor control unit 41 detecting them in accordance with the output timing of the enable signal SE, and are converted into detection signals DSU, DSV and DSW. Signal interval measurement unit 45
(See FIGS. 2 (d), (e) and (f)). Details will be described later.

Further, the motor control section 41 obtains six base signals based on these three detection signals DSU, DSV and DSW, and transmits these base signals to the transistor 6 of the drive circuit 3.
To 11 so that the transistors 6 to 11 are turned on and off in sequence, so that the stator windings 22U, 22V and 2
Energize 2W to rotate the rotor. Then, motor 2
1 drives the compressor 46.

The signal interval measuring section 45 detects the detection signal D
A timer (not shown) measures a time Tn between a rising edge of any one of the signals SU, DSV and DSW and a falling edge of any one of the following signals. The electrical angle between these edges is 60 degrees.
Further, since the motor 21 has four poles, the electrical angle period during one rotation is 720 degrees for two periods, and the measurement section of the time Tn in one rotation period is 12 (that is, n = 1 to 12) ( FIG. 2 (g)).

Then, the PWM pattern determination unit 43 compares the times Tn sequentially measured and output by the signal interval measurement unit 45 and detects the longest time Tl among them. That is, when the motor 21 is rotating completely uniformly, all the times Tn should be equal. However, when driving a load such as the compressor 46, uneven torque and uneven rotation are inevitably generated, and the length of time Tn varies depending on the "unevenness".

Therefore, the variation pattern of the load torque when the motor 21 drives the compressor 46 is measured in advance, and the pattern having the opposite phase to the variation pattern is determined by PW
The M signal pattern is stored in the storage section 43a of the PWM pattern determination section 43. In this case, since the electrical angle period during one rotation of the motor 21 is two, there are two types of load torque fluctuation patterns (see FIG. 3A), and the PWM signal pattern also corresponds thereto. Then, a pattern whose phase is different by 180 degrees in rotation angle is also stored (see FIG. 3C).

When the PWM pattern determination unit 43 detects the longest time Tl as the reference position of the rotor, the PWM pattern determination unit 43 determines whether the longest time Tl is in an area of n = 1 to 6 or an area of n = 7 to 12. It is determined whether or not the PWM signal pattern is read from the storage unit 43a according to the result.

For example, as shown in FIG. 3 for the U phase, when the longest time Tl is T9, it belongs to the region (see FIG. 3 (e)), and the assumed load torque fluctuation pattern is shown by a solid line. Yes (see FIG. 3 (a)), the PWM signal pattern is selected as shown by the solid line which is the reverse phase pattern (see FIG. 3 (c)). On the other hand, if the longest time Tl is T3, it belongs to the area, and the assumed load torque fluctuation pattern is indicated by a broken line, and the PWM signal pattern is selected.

Further, since the speed of the rotor of the motor 21 is the slowest during the period of the longest time Tl (for example, n = 3) (see FIG. 3B), the PWM pattern determination unit 43 Motor control is performed by synchronizing the PWM signal pattern (corresponding to the zero-cross point of the fluctuation level) according to the position of the rotor with the (temporal) midpoint of the period (n = 3) as a trigger. Output to the section 41 and the enable signal generating section 44. Then, the motor 21 is driven by the PWM signal pattern according to the reverse phase pattern of the load torque fluctuation pattern via the motor control unit 41 and the drive circuit 3, so that the fluctuation amount of the load torque is canceled and the motor 21 is substantially constant. It rotates with the torque and speed of.

By the way, as described above, the control unit 40
In actual operation, pulse width modulation (PWM) control is performed to adjust the output based on the speed command signal SV. Specifically, the motor control unit 41
Is the motor 21 based on the position detection signal obtained by the calculation.
Speed detection signal DV indicating the actual rotation speed of
This is given to the voltage command signal generator 42. Then, the voltage command signal generator 42 compares the speed command signal SV with the speed detection signal DV, and provides a PWM duty signal to the PWM signal generator 43 such that the difference between the two becomes zero.

The PWM pattern determination section 43 outputs a PWM signal (PWM carrier) having a duty corresponding to the duty signal given from the voltage command signal generation section 42 and gives it to the motor control section 41. 4
1 modulates, for example, a base signal supplied to the transistors 6, 7 and 8 on the positive terminal side of the drive circuit 3 by a PWM signal.

Accordingly, the terminal voltage UV also becomes a pulse-like voltage as shown in FIG. 4A, and the zero-crossing point detection signal DSU 'obtained by comparing this with the reference voltage VR also becomes a pulse-like voltage as described above. . Therefore, as shown in FIG. 4B, the enable signal generator 44 generates the enable signal SE in synchronization with the PWM signal, and determines whether or not there is a pulse of the phase signal DSU 'only when the enable signal SE is generated. In this way, a continuous rectangular wave signal DSU is obtained as shown in FIGS.

At this time, the enable signal SE is set to be output within the ON period of the PWM signal. However, the induced voltage appearing at the terminal voltage may oscillate immediately after the PWM signal changes from off to on. Therefore, the signal is output so as to be turned on (high level) with a time lag corresponding to the time. Further, the off timing of the enable signal SE is made to coincide with the off timing of the PWM signal.

As shown in FIG. 4, the enable signal S
By performing the position detection of the rotor during the period in which E is output, the position detection signal includes a detection error σ within the range of Expression (1). 0 <σ <TPWM × (1-Dty) + Trag (1) where, TPWM: period of PWM signal Dty: duty ratio of PWM signal Trag: time lag of enable signal SE

If this detection error σ is sufficiently small with respect to the speed fluctuation (unevenness), it can be ignored, and synchronization of the PWM signal pattern according to the position of the rotor can be taken without any problem. If σ is not sufficiently small with respect to the speed fluctuation, the speed fluctuation is buried in the detection error σ and cannot be recognized.

In order to cope with such a case, when the rotation speed of the motor 21 reaches a predetermined value, the PWM pattern determination unit 43 determines that each output interval T1 of the position detection signal measured by the signal interval measurement unit 45 during that time. The reference position of the rotor is determined on the basis of the result of averaging each of T12. Then, since the cycle of the PWM signal is asynchronous with respect to the rotation cycle of the motor 21, the influence of the detection error σ due to the PWM control can be reduced by averaging the output intervals T 1 to T 12, respectively. The fluctuation can be made apparent.

The reference position of the rotor is detected only once during the operation at a constant speed after the start of the motor 21, as shown in FIG. After that, the state shifts to the steady operation state according to the speed command, and it is not necessary to perform the operation unless the rotation of the motor 21 is stopped. Further, the load torque of the compressor 46 varies depending on the state of the refrigerant, the rotation speed of the motor 21, and the like.
If the generated torque is not changed, there is a possibility that the rotational unevenness will be larger.

However, this change depends on the rotation speed of the motor 21 and the average duty information of the PWM signal (the average value of the duty ratio in the PWM signal output within a certain period) given by the microcomputer that controls the refrigerator itself. Once determined, it can be uniquely determined.

Therefore, when the compressor 46 is driven by the motor 21, the variation patterns of the load torque are measured in advance for a plurality of assumed load conditions, and the reverse phase pattern corresponding to the plurality of variation patterns is converted to the PWM signal. The storage unit 43 of the PWM pattern determination unit 43 as a pattern
a (see FIG. 6). Then, the PWM pattern determination unit 43 obtains the average rotation speed of the motor 21 from the position detection signals DSU to DSW given from the motor control unit 41, and estimates the load state from the average rotation speed and the average duty information of the PWM signal. What kind of PWM
It is determined whether to output a signal pattern, and the determined PWM signal pattern is read from the storage unit 43a and output to the motor control unit 41.

As described above, according to the present embodiment, the motor 2
1, when the compressor 46 is driven, the comparators 37, 38, and 39 and the motor control unit 41 detect the zero-cross point of the induced voltage generated in the motor 21, output the position detection signals DSU to DSW, and output the PWM pattern determination unit. 43, the output interval time Tn of the position detection signals DSU to DSW measured by the signal interval measuring unit 45 is the maximum value Tl
Is determined as a reference position.

The PWM based on the reverse phase pattern of the fluctuation pattern of the load torque of the motor 21 measured in advance.
The signal pattern is stored in the storage unit 43a using the reference position as a trigger.
Then, the motor 21 is driven and controlled by reading it out and outputting it to the drive circuit 3 via the motor control unit 41.

Therefore, when driving a compressor in which load torque fluctuation is inevitable, such as the compressor 46, the motor 21 cancels the uneven load torque by the PWM signal based on the reverse phase pattern of the load torque fluctuation pattern. Thus, even when the motor 21 is driven by the sensorless driving method, the load torque unevenness can be reduced with a simple configuration.

Further, according to the present embodiment, when the number of rotations of the motor 21 reaches a predetermined value, the PWM pattern determination unit 43 determines each of the position detection signals DSU to DSW measured by the signal interval measurement unit 45 during that time. Since the reference position of the rotor is determined based on the result of averaging the output intervals, the rotor position detection error σ generated when performing the PWM control is compared with the fluctuation of the rotation speed of the motor 21. Even if the size is not negligible, the influence of the PWM control can be reduced by averaging the output intervals. In addition, the determination of the reference position is made one after the start of the motor 21.
Since the determination is performed only once, the determination processing can be minimized.

Further, according to the present embodiment, the storage section 43a
In addition, a plurality of PWs according to a plurality of load torque fluctuation patterns measured in advance for driving states different depending on the load.
The M signal pattern is stored, and the PWM pattern determination unit 43
Estimates the load state from the average rotation speed of the motor 21 and the average duty information of the PWM signal, selects one of the plurality of PWM signal patterns based on the estimation result, and outputs the selected signal to the drive circuit 3. did. Therefore, as in the case where the load is the compressor 46, the load torque is
In the case of a motor that is known to change according to the number of rotations of 1 or the like, it is possible to reduce load torque unevenness of a motor that varies depending on a driving state.

The present invention is not limited to the embodiment described above and shown in the drawings, and the following modifications or extensions are possible. The determination of the reference position at which the PWM signal pattern is output in synchronization with the rotational position of the rotor is not limited to the one based on the maximum value Tl of the output interval time Tn, but is determined based on the minimum value T1.
It may be performed based on s. Comparators 37, 38 and 39
Accordingly, a magnetic detection element such as a Hall element may be disposed on the rotor as a position sensor (rotor position detection means) without being limited to the sensorless drive method for detecting the zero cross point of the induced voltage of the motor 21. With this configuration, if the output interval of the signal from the position sensor is measured by the measuring unit, the motor 21 is not affected by the PWM control.
The fluctuation of the rotation speed can be detected more easily.
Therefore, in this case, it is not necessary to take the average of each time Tn to detect the reference position of the rotor.

The motor is not limited to four poles, but may have two poles or six or more poles. When the motor has two poles, only one phase of the PWM signal pattern to be stored in the storage means may be used. In addition, when the variation pattern of the load torque is constant irrespective of the driving state, only the PWM signal pattern stored in the storage means needs to store only the pattern corresponding to the constant variation pattern. The load is not limited to the compressor 46, and any load can be applied as long as the load causes periodic load torque fluctuations during driving.

[0054]

The present invention is as described above. The control means determines the rotor position at which the output interval of the rotor position detection signal measured by the measuring means is a minimum value or a maximum value as a reference position, and measures in advance. The drive control of the motor is performed by reading out the energization signal level pattern based on the reverse phase pattern of the fluctuation pattern of the load torque of the motor from the storage means based on the reference position and outputting the pattern to the drive means. Therefore, the motor is driven by the energization signal based on the reverse phase pattern of the load torque fluctuation pattern, and acts so as to cancel the load torque unevenness. Therefore, it is possible to reduce the load torque unevenness of the motor with a simple configuration. Can be.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an electrical configuration showing an embodiment of the present invention.

FIG. 2 is a timing chart showing a relationship between a terminal voltage waveform generated in a winding of a brushless motor and a position detection signal.

FIG. 3 is a timing chart showing a relationship between a fluctuation pattern of a load torque and a PWM signal pattern.

FIG. 4 is a timing chart showing a relationship between a terminal voltage waveform as a result of PWM control and an enable signal;

FIG. 5 is a diagram showing a speed control state after starting the brushless motor.

FIG. 6 is a diagram showing a change in torque when the speed of the brushless motor changes.

[Explanation of symbols]

3 is a driving circuit (driving means), 21 is a brushless motor (motor), 22U, 22V and 22W are stator windings (winding), 37, 37 and 39 are comparators (rotor position detecting means), 41 is a motor. Control unit (rotor position detection means,
(Control means), 43 is a PWM pattern determination section (control means), 43a is a storage section (storage section), 45 is a signal interval measurement section (measurement section), and 46 is a compressor (load).

Claims (8)

[Claims] 1. A rotor position detecting means for detecting a rotor position of a motor driven by a driving means at every predetermined electrical angle and outputting a position detection signal; Measuring means for measuring an output interval; storage means for storing an energization signal level pattern based on a reverse phase pattern of a variation pattern of the load torque of the motor measured in advance; and the output interval measured by the measuring means is Determine the minimum or maximum rotor position as a reference position,
Control means for controlling the drive of the motor by reading out an energization signal level pattern stored in the storage means based on the reference position and outputting the pattern to a drive means. Reduction device. 2. The apparatus according to claim 1, wherein the rotor position detecting means detects the rotor position by a magnetic detecting element disposed on the rotor. 3. The apparatus according to claim 1, wherein the rotor position detecting means detects the rotor position by detecting a zero cross point of an induced voltage generated in a winding of the motor. 4. The control means determines the reference position of the rotor based on the result of averaging each output interval of the position detection signal measured by the measurement means during the rotation of the motor reaches a predetermined value. The apparatus for reducing uneven load torque of a motor according to any one of claims 1 to 3, wherein: 5. The control device according to claim 1, wherein the control unit determines the reference position only once after starting the motor.
The load torque unevenness reduction device for a motor according to any one of the above. 6. The storage means stores a plurality of energization signal level patterns corresponding to a plurality of load torque fluctuation patterns measured in advance for driving states different depending on the load. The load state is estimated from an energization signal, and one of the plurality of energization signal level patterns is selected based on the estimation result and read out from the storage unit. 3. The apparatus for reducing uneven load torque of a motor according to claim 1. 7. The storage means stores a plurality of energization signal level patterns having different phases, and the control means determines in which position the reference position of the rotor is detected by the rotor position detection means. 7. The motor load torque unevenness reduction apparatus according to claim 1, wherein one of the plurality of energization signal level patterns having different phases is selected and read out from the storage unit. 8. The apparatus according to claim 1, wherein the load is a compressor.