KR900002420B1 - Speed-controlling method for brushless dc motor - Google Patents

Abstract

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Description

Speed control device of motor and speed control method

1 is a block diagram of a speed control apparatus for an electric motor according to an embodiment of the present invention.

2 is a detailed view of the current control unit.

3 is an operation explanatory diagram.

4 is a detailed explanatory diagram showing the speed control.

5 is an operation explanatory diagram thereof.

6 is a detailed block diagram showing speed control in a speed control apparatus for an electric motor according to another embodiment of the present invention.

7 is an operation explanatory diagram thereof.

8 is a detailed configuration diagram illustrating speed control in a speed control apparatus for an electric motor according to still another embodiment of the present disclosure.

9 is an operation explanatory diagram thereof.

10 is a signal waveform diagram showing the operation of the motor of FIG.

11 is a control statistical diagram showing a speed control method according to an embodiment of the present invention.

FIG. 12 is a diagram showing processing execution timing of the speed control in FIG. 11. FIG.

13 is a control system diagram showing another speed control method of the present invention.

FIG. 14 is a diagram showing processing execution timing of the speed control in FIG.

15 is an explanatory diagram showing changes in load torque, output torque and rotation speed of the motor with respect to the rotation angle of the motor;

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control apparatus for an electric motor, and more particularly, to a speed control apparatus for an electric motor suitable for changing the magnitude of a load applied to the electric motor in a certain period.

In addition, although a brushless direct current motor is often used for a fluctuating load, the present invention relates to a speed control method of a brushless direct current motor of a method of measuring a rotation period by measuring a rotation period in a position detection signal, in particular of a brushless direct current motor. It is about.

The present invention is suitable for a motor for driving a compressor.

For example, as a method of varying the cooling or heating capacity of a room air conditioner (hereinafter, referred to as a room air conditioner), a method of controlling and changing the rotational speed of a compression motor using an inverter has become common.

The rotation speed control range of these electric motors is about 2000 rpm to about 6000 rpm.

If the rotation speed control range is further extended, the capability control range of the room air conditioner is expanded, and the effect of enhancing the heating capacity for high speed rotation and power saving and low noise for low speed rotation is obtained.

For such low-speed rotation of about 1000 rpm or less, vibration and noise increased conventionally for the reason shown next, and it was difficult to put to practical use.

In other words, the compressors used in room air conditioners and refrigerators are generally sealed in the chamber together with the driving motor, and the load torque applied to the motor of the compressor is greatly increased with respect to the rotation angle of either the rotary compressor or the recipe compressor. Pulsating, the maximum load torque is approximately three times the load torque of the average torque, and is repeated in one rotation period.

Here, FIG. 15 shows changes in the hatching torque T _L , the output torque T _M , and the rotation speed N of the motor with respect to the rotation angle.

In the rotation angle region of the city B in which the load torque TL becomes larger than the output torque T _M , the angular acceleration by the decelerator of the rotation speed N is generated, and thus the product of the rotational axis system of the motor with the inertia moment J The rotational inertia torque indicated by i) is generated, and this and the output torque T _M are in balance with the load torque T _L.

For this, (T _L) <and the rotating area of the respective regions shown in A is a rotational inertia torque based on the acceleration of the rotational speed occurs the (T _M). That is, the rotational inertia torque corresponding to the torque difference of (T _M )-(T _L ) is generated, so that the torque equilibrium is maintained between the motor on the output side and the compressor on the load side.

In other words, in an electric compressor, a rotational pulsation occurs in one rotational center, which causes vibration and even noise in the entire compressor chamber.

In particular, when the motor is driven to the low speed region, as the rotation speed decreases, the vibration of the rotational pulsation increases with respect to the angular acceleration as in high speed, and the frequency of the rotational pulsation also decreases.

And, the vibration caused by this also has a large amplitude according to the rotational pulsation and the vibration frequency also decreases.

Therefore, it has been difficult to realize the practicality step in enlarging the rotational speed range of the conventional compressor motor in the low speed direction because the vibration and sound insulation countermeasures are enlarged when vibration and noise are severe.

In order to solve the above problems, for example, the present inventors have developed the Japanese Patent Application No. 59-123639, which was developed by the present inventors. The load torque pattern is stored in advance, and the stored torque pattern data is read out for each rotation angle. The torque control device was developed to control the torque.

However, in the above method, it is assumed that the load torque pattern for the rotation angle is already known. The known case is sufficient, but the point corresponding to the arbitrary load torque pattern or the reference position for the rotation angle is known. There is a point to study, such as the need to detect.

In addition, the brushless motor speed control method, as disclosed in Japanese Patent Application Laid-Open No. 59-44991, measures the time every 60 degrees from the position detection signal, calculates the time of the electrical angle 60n ₁ degree with n ₁ as a positive integer, At this time, the five processes of calculating the rotational speed, calculating the proportionality, integral, and derivative term of the deviation rotational speed between the detected rotational speed and the commanded rotational speed, and determining the output voltage of the inverter based on this, Was doing by. However, it was asynchronous with the measurement of time every 60 degrees of electrical angle which is a 1st process, and the other process following it. That is, a time delay occurs from the calculation result to the inverter output voltage after the time calculation of 60 degrees, which causes a problem that the response speed of the speed control system is lowered.

In particular, when using a brushless DC motor employing a conventional speed control method as a compressor motor, the following problems arise. That is, a compressor used in a room air conditioner or a refrigerator generally has a structure that is sealed in a chamber together with a driving motor, and the load torque applied to the motor of the compressor is the rotation angle of either the rotary compressor or the reciprocating compressor. Pulsating greatly, the maximum load torque is approximately three times the average load torque. Thus, the pulsating load is in a roughly determined pattern with respect to the rotation angle. Therefore, in the method of speed control asynchronously with the position detection signal synchronized with the rotation angle as in the conventional speed control, it becomes difficult to determine the output voltage of the inverter in response to a load that changes according to the rotation angle. As a result, the rotational pulsation occurs due to an increase in the torque between the motor output torque and the load torque. Especially, the vibration of the chamber is increased because the amplitude of the rotating pulsation increases and the frequency of the rotating pulsation decreases at low speed. There was a problem.

A first object of the present invention is to control the speed of an electric motor such that a speed of a load body in which a load changes at a certain period, such as a compressor, can be changed as little and as widely as possible without detecting a reference position. To provide a device.

It is a second object of the present invention to provide a speed control method of a brushless DC motor which can control the speed in response to a high speed even when the load changes with respect to the rotational position.

The structure of the speed control apparatus of an electric motor which achieves the 1st objective of this invention provides the apparatus which controls the voltage or electric current applied to the said electric motor to match the speed of an electric motor and the load body driven by this electric motor with a command speed. In the case where the magnitude of the load imposed on the motor changes during a certain period, the predetermined period is divided by n, and reading and writing to independently store n pieces of data by voltage or current applied to the motor are independently stored. At least one of the n data and at the same time modifying at least one data of the n data according to the difference between the command speed and the speed of the load body at every n divided periods. According to the data, the voltage or current applied to the motor is controlled.

In addition, the description is as follows.

The present invention divides the constant cycle by n for the pulsating load repeated at every constant cycle, and includes data according to the current or voltage applied to the motor in each of the multiple division units, and the command speed and detection of the motor at each constant cycle. At the speed and the speed, the data is corrected, and the voltage or current applied to the motor is controlled based on the data.

In addition, when supplementing with an example of a compressor electric motor is as follows.

In particular, the present invention considers that the output torque of the motor is equal to the load torque in consideration of the fact that the cause of increasing vibration and noise is a mismatch between the load torque of the rotation angle and the output torque of the motor. To control.

As a specific method of designating the load torque without detecting the reference position, one revolution is divided by n, and data for torque is separately generated from the speed difference between the command speed and the detection speed for each division unit. The torque of the motor is output based on these data as a designated load torque pattern.

A speed control method for achieving the second object of the present invention comprises an inverter for converting power from direct current to three-phase alternating current as constituting the apparatus, a synchronous motor of a permanent magnet rotor type driven by the inverter output, and the circuit Means for detecting the magnetic pole position of the former and outputting a position detection signal, wherein n ₁ is a positive integer from the position detection signal to generate a basic signal for each electric angle of 60 n ₁ degree, and the number of revolutions is detected in the period of the signal. In the brushless DC motor of the speed control method which determines the output voltage of the inverter according to the detected rotation speed and the command rotation speed, the process of determining the output voltage of the inverter is synchronized with the position detection signal. is to the n ₂ the speed control method for execution each time the voltage 60n each an integer of ₂ degrees plus.

In other words again, the speed control method of the present invention once the n ₁ and n ₂ in the position detection signal of the electronic as a constant plus the measured time of the electric each 60n _1, and calculation of the number of revolutions per _{second-degree} time 60n from the obtained time And the calculation of the proportional, integral and derivative terms of the deviation rotational speed between the detected rotational speed and the commanded rotational speed which are the calculation results, and the output voltage of the inverter is determined based on the synchronization with the position detection signal and the speed control process. It is possible.

Each embodiment of the speed control apparatus of the electric motor by this invention is demonstrated based on FIG.

Each embodiment is based on the embodiment applied to the brushless DC motor by the compressor motor as an electric motor.

That is, FIG. 1 shows the overall configuration of the speed control device of the brushless DC motor.

In the illustrated AC power supply 1, the DC voltage Ed shown in the rectifier circuit 2 and the smoothing capacitor 3 is obtained and supplied to the inverter 4.

The inverter 4 is a 120 ° energized inverter composed of transistors TR _{1 to} TR ₆ and reflux diodes D _{1 to} D ₆ , and its AC output voltage is a positive plus potential side transistor TR _{1 to} TR of DC voltage Ed. _It is assumed that the passage period of ₃ (electric angle of 120 °) is controlled by the chopper operation under pulse width modulation.

The low resistance R ₁ is connected between the common anode terminals of the common emitter terminals D ₄ to D ₆ of the common emitter terminals of the transistors TR _{4 to} TR ₆ .

Denoted at 5 is a compressor unit, which is composed of a synchronous motor 5-1 having a permanent magnet of 4 poles as a field and a load chain compressor 5-2 by a brushless DC motor.

Synchronous winding current flowing in the armature winding of the motor (5-1) is flowing in the low-resistance R _1, the voltage drop across a low-resistance R _1, it is possible to detect a winding current I _L.

A control circuit for controlling the speed of the synchronous motor 5-1 includes a magnetic pole position detecting circuit 6 for detecting the magnetic pole position of the rotor of the microcomputer 7, the synchronous motor 5-1, and the synchronous motor 5 The speed of the current control unit 8 for controlling the armature winding current of -1), the base driver 9 for the transistors TR _{1 to} TR ₆ , and the synchronous motor 5-1 is set as the speed command (NCMD) shown in FIG. It consists of the speed command circuit 12 which conveys to the computer 7. As shown in FIG.

The magnetic pole position detecting circuit 6 is a circuit for forming the position detecting signal 6S corresponding to the rotor position using a filter circuit at the armature winding terminal voltages V _{A to} V _C of the synchronous motor 5-1. . Then, by using the position detection signal 6S, the rotation speed of the synchronous motor 5-1 is calculated by the microcomputer 7 to calculate.

The ROM 7-2 is memorized by various processing programs necessary for driving the synchronous motor 5-1 by a brushless DC motor, for example, speed calculation processing, command drawing processing, speed control processing, and the like. have.

On the other hand, the microcomputer 7 is composed of a CPU (7-1), ROM (7-2), RAM (7-3) and the like, each connected by an address bus, data bus and control bus (not shown) Will be.

The RAM 7-3 stores main memory 7-3a for reading and writing various data necessary for executing the various processing programs, and twelve pieces of current data relating to winding current values to be passed through for each rotor position. It consists of one current pattern storage section 7-3a.

The current controller 8 controls the winding current I _L in accordance with the current output data 11 outputted at each rotational position based on the current data in the current pattern memory 7-3a of the microcomputer 7. And 10 is a chopper signal to be described later.

In other words, in the brushless DC motor, the winding current flowing in the armature winding corresponds to the output torque of the motor, and by controlling the winding current for each rotation position, control of each rotation position of the output torque becomes possible.

2 shows details of the current control section 8 described above.

That is, the D / A converter 17 as the current command circuit, the amplifier 13 as the current detection circuit, the current comparator 14 for comparing the current command value 11a and the current detection value V _1L , the triangular wave oscillator 15, It is composed of the above-mentioned transistor TR ₁ ~TR ₃ to the comparator 16 to create the chopper signal 10 for the chopper operation.

Of the 12 current data stored in the current pattern memory 7-3a of the microcomputer 7, 8 bits are read out one by one according to the rotation position and output to the outside of the microcomputer 7 based on the current data. The current output data 11 is converted into an analog amount by the D / A converter 17 to become the illustrated current command value 11a.

The winding current I _L obtained as the voltage drop of the low resistance R _{1 described} above is amplified by the amplifier 13 to be the illustrated current detection value V _IL , and compared with the current command value 11a by the current comparator 14. The output 14S and the triangular wave signal 15S, which is the output of the triangular wave oscillator 15, are compared by the comparator 16, and the chopper signal 10 is formed as the output.

3 is an operation explanatory diagram showing the time relationship between the position detection signal 6S and the current command value 11a.

Assuming that the synchronous motor 5-1 is a four-pole machine, one cycle of the position detection signal 6S indicating the magnetic pole position of the rotor in the same plane 1 corresponds to 180 ° in the machine angle, and 1 of the rotor It is divided into 12 modes every 30 ° from the mode "1" to the mode "12" shown for rotation 360 °.

For each of these modes, twelve 8-bit current data generated by the method described below and stored in the current pattern storage unit 7-3b are read out according to each mode. The current output data 11 output based on the read current data is converted into the current command value 11a by the D / A converter 17 as shown in FIG.

As described above, the current detection value V _1L and the current command value 11a are compared to generate an offer signal 10, and the winding current I _L is controlled by a waveform corresponding to the current command value.

Next, a method of correcting and outputting twelve pieces of current data stored in the current pattern storage unit 7-2b will be described next with reference to FIGS.

4 is a detailed block diagram showing the processing contents of the microcomputer 7 in this embodiment in a block.

The input includes the position detection signal 6S from the magnetic pole position detection circuit 6 and the speed command NCMD from the speed command circuit 12.

In the speed calculation process 18, the speed is calculated and calculated from the rotation time of the rotor every 30 degrees of the machine angle of the position detection signal 6S.

In the command induction process 19, the speed command NCMD is read and an internal speed command INCD is created.

The current pattern storage section 7-3b described above is composed of _twelve integral terms I _{1 to} I _{12 shown} in the above-described current data.

Here, I ₁ = ∑ (INCMD-N ₁ ), where N ₁ is the rotational speed in the mode “i”.

On the other hand, the switches SW ₁ and SW ₂ respectively indicate which one of the 12 integral terms are selected on the input side and the output side, and two switches SW ₁ each time the rotor rotates by 30 °. ) And (SW ₂ ) are assumed to be switched.

The integral term selected by the switch SW ₂ is subtracted by the proportional term P in the figure, and is output to the D / A converter 17 as the current output data 11. Here, the proportional term P is data obtained by multiplying the speed CURN detected by the speed calculation process 18, that is, P = K CURN.

Next, FIG. 5 shows the detection speed and the modified integral term (i.e., current data) for each mode from the mode " 1 " to the mode " 12 " ) And a diagram showing the operation of the current output data.

At any point in time t, when the rotational position reaches the position of mode "i", the speed that can be detected in this mode "i" is the mode "i-1" in front of it (the mode when i = 1). "12") is the rotational speed N _i-1 , and the integral term Ii-1 is corrected according to the following expression by the detection speed N _i-1 and the internal speed command INCMD at that time.

I _i-1 = (INCMD-N _i-1) + I _i-1 ... … … … … … … … … … … … (One)

Here, the integral term I _i-1 on the right side is an integral term up to that point in time, and in general, the integral term I _i for the mode "i" is obtained as follows.

I _i = ∑ (INCMD-N _i) . … … … … … … … … … … (2)

On the other hand, the current output data in the mode "i" is the difference between the integral term I _i and the proportional term P = KN _{i-1 which} are already corrected in the mode "i + 1" near one rotation. , I _i -K · N _i-1 . Where K is the proportional term gain.

As described above, one rotation 360 ° is divided into 12 rotational positions every 30 °, and each rotational position is provided in an area of RAM capable of reading and writing the integral term as current data independently corresponding to the divided positions. As a result of creating the integral term in the difference between the speed at the rotational position and the command speed, the pattern of one rotation 360 ° formed by the 12 integral terms approximates the pulsation pattern of the compression load.

Then, in the mode "i" corresponding to any arbitrary position, the processing of the microcomputer 7 performs the calculation and integration of the speed in the mode "i-1" corresponding to the previous rotational position as described above. After correcting the term, the current output data is outputted by the proportional term (P) obtained from the integral term I _i already corrected just before one revolution and the speed calculated at that time.

As described above, 12 integral terms are corrected for each revolution, and the modified integral terms are reflected in the current output data immediately after one revolution. From this point, for an abrupt load, the response of the integral term is slow.

On the other hand, in the above embodiment, the velocity in the one preceding mode detected by a certain mode is reflected in the current output data as a proportional term, thereby compensating for the slowness of the response of the integral term, and as a result, the current output. The response of the data is quick.

Next, another embodiment will be described based on FIGS. 6 to 7 as a method of creating current data stored in the current pattern storage unit. 4 and 5 and the same reference numerals are the same parts, (7-A) is a microcomputer (7-3 b-1) is a current pattern storage unit.

That is, the difference from the embodiment shown in FIG. 4 and FIG. 5 is that the current data is corrected based on the rotational speed in two modes, that is, the speed in the period of 60 ° of machine angle, for 12 modes of one rotation. That's one point.

6 is a detailed block diagram of the contents processed by the microcomputer 7-A similarly to FIG.

That is, two integral terms that are current data are obtained by the difference between the internal speed command (INCMD) obtained by the command drawing device (19) and the speed (CURN) detected by the speed calculation process (18). At the same time, one integral term is reflected in the current output data.

7 is similarly to FIG. 5, in each mode of 12 revolutions of one rotation, the operation time which shows the measurement time of the speed to detect, the content of a detection speed, the integral term as the current data to correct, and the current output data are shown. It is explanatory drawing.

For any mode "i", the detectable speed is the duration of the mode "i-1" and the mode "i-2" (if the modes "11" and "12" when i = 1 and i = 2). Is the speed N _{(i-2) (i-1)} at the modes " 12 " and " 1 &quot;, and the detected speed N _{(i-2) (i-1)} and the interior at that time. Modify the two integral terms in the speed command (INCMD) according to the following equation.

I _i-2 = (INCMD-N _{(i-2) (i-1)} ) + I _i-2 ... … … … … … … … … … … (3))

I _i-1 = (INCMD-N _{(i-2) (i-1)} ) + I _i-1 ... … … … … … … … … … … (4)

Here, the integral terms I _i-2 and I _i-1 on the right side in the above equations are the same as those of the expression (1) above. Integral term.

On the other hand, the current output data 11 in the mode " i " is the integral term I _i and the proportional term P which have already been corrected by the mode " i + 1 " and the mode " i + 2 " It is set as I _i -K * N _{(i-2) (i-1)} as a difference of = K * N _{(i-2) (i-1)} .

In the second embodiment shown in Figs. 6 to 7, the time every 30 degrees of the position detection signal 6S used for the speed detection depends on the precision of the components constituting the magnetic pole position detection circuit 6, When only 30 ° time does not reflect the speed correctly, speed detection is performed with high accuracy based on the time every 60 °, and two integral terms are corrected from this to output the current output data of the component precision. The effect was to reduce the impact.

In addition, in order to obtain the same effect as the above in this embodiment, one term to be corrected may be used, and two integral terms reflected in the current output data may be used.

That is, in the mode "i", the integral term to be corrected is I _i-2 only, and the integral values reflected in the current output data are selected two of I _i and I _i-1 , and the current output data (( The same effect can be obtained even if I _i + I _i-1 ) -K · N _{(i-2) (i-1)} .

Furthermore, the present invention relates to a method of correcting and outputting current data stored in the current pattern storage unit. The other embodiment, that is, the third embodiment, will be described with reference to FIGS.

In Fig. 4, the same reference numerals as those in Figs. 4 and 5 denote the same parts, (7-B) is a microcomputer, and (7-3b-2) is a current pattern memory.

That is, the current data is different from each of the above-described embodiments in that twelve proportional terms are prepared in addition to the integral terms, and twelve current data paired with the integral term and the proportional term correspond to each of the 12 modes.

8 is a detailed block diagram showing the contents processed by the microcomputer 7-B of speed control in the same manner as in FIG.

In other words, together with 12 integral terms I _{11 to} I ₁₂ , 12 non-respective terms P _{1 to} P ₁₂ are paired, respectively, and the current pattern storage unit 7-3b-2 is generated by 12 current data. To construct.

A pair of these proportional values and the integral term are respectively corrected for each rotational position of 30 ° by the switch SW ₁ and the microcomputer 7-B is selectively used as the current output data 11 by the switch SW ₂ . Is output from

9 shows the speed detected, the proportional term as the current data to be corrected, the integral term and the current output data in each mode of the mode "1" to the mode "12" with respect to the rotational position every 30 degrees. This is an operation diagram.

The detectable speed in the mode "i" is N _i-1 (N ₁₂ when i = 1). The detected speed N ₁₂ and the internal speed command (INCMD) at that time are proportional terms according to the following equation. Write (P _i-1 ).

P _i-1 = K (INCMD-N _i-1 )

Where K is the gain of the proportional term.

On the other hand, the integral term I _i-1 is modified similarly to the formula (1) in the above-described embodiment.

The current output data output in the mode "i" is the sum of the integral term I _i and the proportional term P _i already corrected in the mode "i + 1" near one rotation, and I _i = P _i Shall be.

In the present embodiment described above, the proportional term is created based on the speed in the mode such as the integral term, and the current output data 11, in other words, the current command value which is the analog amount, that is, 1 of the motor output torque. The approximate accuracy between the pattern per revolution and the pattern of the pulsating compression load is increased, and the effect of reducing the speed pulsation is high.

According to each of the embodiments described above, the brushless DC motor is used as the compressor motor to control the speed of the motor. In summary, the following effects can be obtained.

(1) The cycle is divided into 12 rotational positions every 30 ° with respect to the pulsating load pattern approximately determined by the rotational position, and the speed is detected for each of the divided rotational positions. The current torque data is stored in a RAM that can be read and written while modifying the current data, and the output torque pattern is divided into 12 parts by pulsating a load pattern in a cycle of controlling the current of the brushless DC motor, that is, the output torque. The pattern is approximated to.

As a result, the difference between the load torque of the compressor and the output torque of the motor is reduced, and the speed pulsation generated by the difference torque is reduced.

Thereby, even if the motor for compressor is expanded to the low speed operation area of 1,000 rpm or less, an electric compressor with few vibrations is obtained.

(2) In addition, as described above, the output torque pattern of the motor is generated, and the output torque pattern and the load torque pattern are rotated at the angle of rotation only by using the magnetic pole position detection signal of the rotor obtained from the armature winding terminal voltage. Since there is no need to install a sensor for detecting the rotational reference position or a sensor such as a taco generator or encoder for detecting the speed on the motor side, there is no increase in the number of parts and reliability. To improve.

Next, the control method of the brushless DC coater will be described based on the configuration of the speed control circuit of FIG. 1 and FIGS. 10 to 14.

10 is a signal waveform diagram of each part of the main circuit showing the operation of the brushless DC motor. 10A shows position detection signals 6S, which are outputs of the magnetic pole position detection circuit 6, and (b), for example, timing signals PS at 60 degrees of electrical angle, (c) are triangular plate carriers, It has a constant oscillation frequency. (d) is a modulation signal produced by the slice level D _{1 shown} in (c) above, and the drive signal e of the transistor is generated by logic processing with the position detection signal 6S shown in (a). The rotation speed of the brushless DC motor is determined by changing the output voltage of the inverter 4 by the slice level D ₁ .

11 is a control system diagram according to the speed control method of the present embodiment, which is realized by the configuration of the control circuit of FIG. First, in I ₁ of FIG. 11, the cycle of the two period parts T ₁ + T _1-1 of the timing signal PS (Fig. 10 (b)) for every 60 degrees of electric angle is tripled to correspond to one cycle. The time T of minutes is calculated, and in the next I ₂ , the rotation speed N is calculated by N = K / T (K is a constant), and the detected rotation speed N and the command rotation speed in I ₃ are calculated. Find the proportional, integral, and derivative terms (K _P ), (K _I ) and (K _D ) of the rotational speed with N _R, and determine the slice level D ₁ from the sum (K _P + K _I + K _D ). These processes are performed in synchronism with the PS signal every 60 degrees of electric angle in the microcomputer 7 or the like in the control circuit.

12 is a diagram showing the time relationship between the PS signal and the processing. The processes (I ₁ ), (I ₂ ), and (I ₃ ) are performed at once in succession every 60 degrees of electrical angle, while information for rotation count calculation is performed for two cycles of the latest PS signal at each execution of the processing of I ₁ . Time of 120 degrees of electric angles corresponding to minute shall be used.

According to the above method, the nonuniformity of the measured value generated every cycle is averaged by using the PS signal and two cycles as the rotational speed information, and the time measurement result for two cycles is immediately reflected to the slice level D ₁ . This improves the accuracy of and improves the response of the speed control system accompanying the change in rotation.

Another embodiment of the present invention will be described with reference to FIGS. 13 and 14. 13 is a control system diagram showing a speed control method according to the present embodiment. The difference from the control system shown in FIG. 11 is that the calculation of the time T of one cycle in II ₁ is switched at high speed and low speed, and also the execution cycle of the processes leading to II ₁ , II ₂ , and II ₃ is also switched. The processing contents of II ₂ and II ₃ are the same as those of FIG.

That is, since a certain time is required to execute the high speed control processing in the microcomputer or the like, one cycle of the PS signal is shortened at high speed, and processing within this one cycle becomes difficult. In order to avoid this, in the high-speed rotation region, in the embodiments shown in Figs. 13 and 14, the processing by the speed control is performed every three cycles of the PS signal, i.e., every 180 degrees. Also, in the high-speed rotation region, the influence of the nonuniformity of the components of the position detection circuit by the position detection signal increases the nonuniformity of the period of the PS signal, so that the processing of II ₁ is executed as the information on the rotation count calculation. Each time is averaged using an electric angle of 360 degrees corresponding to six cycles of the latest PS signal.

14 is a diagram showing the relationship between the PS signal and the processing (II ₁ ), (II ₂ ) and (II ₃ ) in the high speed rotation region. Each process is executed in synchronization with the PS signal at every 180-degree electric time in succession, and the information for rotation count calculation uses the time for the six cycles of the latest PS signal each time.

Here, the same effects can be obtained even if the three processes of II ₁ , II ₂ , and II ₃ are not performed continuously, but each process is divided and each process is performed in synchronization with the PS signal.

Although each of the above embodiments is described as a brushless DC motor by a compressor motor as an electric motor, the present invention is not limited to this, for example, the load of a load body driven by the electric motor in any one fixed cycle. Is a general purpose that can be used as a speed control device of an electric motor having a device capable of detecting a change in speed during the predetermined period and controlling the speed by controlling a current or voltage applied to the motor. will be.

Incidentally, according to the above embodiments, the current applied to the motor is controlled, but this is referred to as the control of the rotation speed, and the voltage controlled to control the voltage applied to the motor.

Incidentally, in the above embodiment, an inverter device is used as the current control device, but this can be used as a chopper device in a direct current power source, and the same applies to the case where both are used as voltage control devices.

The present invention can also be applied to a linearly moving electric motor, that is, a linear motor.

In other words, the present invention is practiced as a drive motor for varying load torque at predetermined cycles.

As described above, according to the speed control device of the present invention, it is possible to obtain a speed control device for an electric motor which is suitable for changing the speed of the motor widely according to the command speed and further reducing the speed pulsation. At the time of implementation, it can implement | achieve only by detecting a speed, without detecting the position used as the reference | standard which a load body moves, and it is not necessary to know the amount of change of the load which changes in a fixed period beforehand, and it is industrially advantageous.

Further, according to the speed control method of the present invention, the speed control is performed every time of the electric angle of 60n ₂ degrees of the position detection signal, and the load is pulsated with respect to the rotational position, for example, like a brushless DC motor for compressor driving. In particular, the effect is remarkable, and the change in the number of revolutions caused by the load change can be quickly reflected in the inverter output voltage, and the speed control system becomes high speed, thereby realizing a brushless DC motor with low rotational pulsation. Further, according to the embodiment of the present invention, n ₂ is larger than at low speed in consideration of the processing time of the speed control system in the high speed rotation region in which the rotational speed change caused by the load change is alleviated by the increase of the inertia force generated by the load and the motor. By doing so, as described above, rotational pulsation can be suppressed and response can be improved.

Claims (2)

An electric motor and a device for controlling the voltage or current applied to the electric motor to match the speed of the load body driven by the electric motor with the commanded speed, wherein the magnitude of the load applied to the electric motor changes during a certain period. And a memory element capable of separately dividing the predetermined period by n and storing and reading and writing n pieces of data by voltage or current applied to the motor independently, wherein the command speed and the load are carried out for each of the n divided periods. And modifying one or more pieces of data of the n pieces of data according to a difference between the speeds of the two pieces of data and controlling the voltage or current applied to the motor in accordance with one or more pieces of data of the n pieces of data. Speed controller. An inverter for converting power from DC to three-phase alternating current, a synchronous motor of a permanent magnet rotor type driven by the inverter output, and means for detecting a magnetic pole position of the rotor and outputting a position detection signal. create and n ₁ an integer of the positive from the signal post primary signals of the 60n per ₁ also the output voltage of the inverter in accordance with the detected rotational speed and reference rotational speed by detecting the rotation speed of the rotor is in a cycle of the signal In the control of the motor for determining and controlling the speed, the process for determining the output voltage of the inverter is performed in synchronization with the position detection signal, and n ₂ is performed every 60 n ₂ degrees of electric angle as a positive integer. Motor speed control method

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