JP3236322B2 - Operation control device for DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse width variation of a DC motor.
The present invention relates to a DC motor operation control device that reduces fluctuations in the rotational speed due to periodically generated torque pulsation in rotational speed control using modulation control (hereinafter, referred to as PWM control ) .

[0002]

2. Description of the Related Art In recent years, DC motors have high efficiency,
Due to the easiness of rotation speed control, its application range is expanding.

[0003] A conventional operation control method for a DC motor will be described below. Generally, the control of the rotation speed of the DC motor
This is performed by controlling the voltage applied to the electric motor.
In recent years, PWM control has been widely used as a method of changing the voltage. For example, by turning on / off a semiconductor switch on one side of the inverter circuit at a chopping frequency higher than the driving frequency, it is possible to control the rotation speed. At this time, the voltage is adjusted by the ratio of the chopping duty on to off. Further, in order to obtain a constant rotation speed, the rotation speed is obtained from the frequency of the position detection circuit, and the chopping duty is adjusted so as to approach the target rotation speed.

However, such a method is effective for a load that generates a constant torque, but performs a process such as suction, compression, and discharge during one rotation like a compressor of an air conditioner or a refrigerator. In the case of such a load, the load torque changes during one rotation. Therefore, when paying attention microscopically, the rotation speed decreases when the load torque is large, and conversely, the rotation speed increases when the load torque is small. This speed fluctuation causes vibration and noise of the compressor.

In order to solve this problem, it is conceivable that torque is generated when necessary, and speed control is performed in finely divided sections so as to suppress the generation of torque when unnecessary. As an example of this method, there is a method as disclosed in Japanese Patent Application Laid-Open No. 2-193589. In order to control the number of rotations of the DC motor, an independent controller is provided for each section obtained by dividing one rotation, and the speed is controlled for each section.

[0006]

However, the conventional configuration as described above has the following problems.

[0007] In the conventional method, for controlling the speed in a way that completely made independent for each section, for example, when the rotational speed of such during or deceleration acceleration is not constant of the freely duty in each section In this case, the imbalance occurs, and rather a large speed fluctuation occurs. There is a problem that vibration and noise increase due to the speed fluctuation.

[0008] In addition, similarly resulting imbalance, such as when the data of one of the controller due to a disturbance such as noise or the like has changed write, the speed variation occurs, stomach or to become a higher vibration and noise, also the There is also a problem that it takes time to return from the state.

Further, since an individual controller is required for each section, the cost is increased. An object of the present invention is to solve the above-mentioned conventional problems, and it is possible to maintain a stable rotation speed even during acceleration or deceleration, reduce the influence of disturbances such as noise, and realize an inexpensive DC motor operation control device. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION The operation control device for a DC motor of the present invention in order to achieve the object, a position detection circuit for generating a rotation pulse and detects the position of the rotor of the DC motor, position detection The rotation pulse of the circuit is
The rotation speed detection circuit to be started, the set rotation speed and the rotation speed
From the difference between the actual rotation speeds detected by the detection circuit,
Adjust the duty so that they match, and
Due that generates a match signal when a match is made within the specified range
A tee setting circuit divides the DC motor N phases per revolution of the rotation pulses of the position detecting circuit, a cycle determining circuit for generating correction data from the difference between the period of the measured target period for each section, Set target speed and actual speed.
Connection means that is turned on only when there is a match within the specified range
When the correction data storage circuit for storing correction data output of the period determination circuit for each section, and a state selection circuit for selecting the correction data referred to duty correction circuit for correcting the chopping duty based on the correction data selected It has a configuration.

In another configuration, in addition to the above configuration, correction data is checked and a preset maximum value is checked.
There is a limiting circuit that allows each correction data to be within the value / minimum value .

[0012]

According to this configuration, the target rotation speed and the actual rotation speed are obtained.
The cycle is measured for each section based on the duty adjusted based on the difference from the target cycle, the displacement with respect to the target cycle calculated from the target rotation speed is obtained, and the correction amount to be performed in the next section is calculated based on the result. Ask for. That is, unlike the conventional case, by having data as a correction value from a predetermined duty, no imbalance occurs during acceleration or deceleration.
No.

Further, the correction data of the period determination circuit is
Output only when the target rotation speed and the actual rotation speed almost match.
And store it in the correction data storage circuit to determine the cycle.
Cancel when unstable, such as during acceleration or deceleration.
Since it is performed only at a stable time, speed fluctuations can be suppressed , and vibration and noise can be reduced.

In another configuration, the correction data is checked.
Check each value within the preset maximum and minimum values.
By providing a limiting circuit that allows the positive data to enter, even if the data in the correction data storage circuit has been rewritten due to disturbances such as noise , the limit circuit returns the data to almost the correct value, and quickly returns to the correct value. will be convergence, reduce the speed variation, and Ru can reduce the vibration and noise
Both can be returned promptly to the normal state, the electric motor
The compressor operating condition, which is a load that leads to
The operation of air conditioners and refrigerators incorporating this compressor.
Improve rate.

[0015]

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

FIG. 1 is a block diagram of a DC motor operation control device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an AC power supply. Reference numeral 2 denotes a rectifier circuit for converting an AC voltage of the AC power supply 1 to a DC voltage.

Reference numeral 3 denotes an inverter circuit, in which semiconductor switches (transistors in this embodiment) 3a to 3f are connected in a three-phase bridge, and are connected in parallel to each transistor.
Diodes 3g to 3l are connected in the opposite direction.

Reference numeral 4 denotes a DC motor, and an inverter circuit 3
Driven by the output of Reference numeral 5 denotes a position detection circuit that detects the rotational position of a rotor (not shown) of the DC motor 4 and generates a rotation pulse. In this embodiment, a position detection circuit detects the position from the back electromotive voltage of the DC motor. The rotation pulse is generated at the rising and falling edges of the position detection signal, and generates 12 pulses per rotation of the rotor.

Reference numeral 6 denotes a commutation circuit for generating a signal for commutating the semiconductor switches 3a to 3f of the inverter circuit 3 from the output of the position detection circuit 5. Reference numeral 7 denotes a chopping signal generation circuit for generating a signal for performing PWM control for making the rotation speed of the DC motor 4 variable, and generates waveforms having different on / off ratios at a constant frequency in accordance with a command.

Numeral 8 denotes a synthesizing circuit for synthesizing the output of the commutation circuit 6 and the output of the chopping signal generating circuit 7, and chops only one arm of the inverter circuit 3. Reference numeral 9 denotes a drive circuit for operating the semiconductor switches 3a to 3f of the inverter circuit 3 according to the output of the synthesis circuit 8 .

Reference numeral 10 denotes a rotation speed setting circuit for setting the rotation speed of the DC motor. Reference numeral 11 denotes a rotation number detection circuit that counts rotation pulses of the position detection circuit 5 for a predetermined time (for example, 0.5 seconds). 12 adjusts the set speed set by the rotational speed setting circuit 10, the difference between the actual rotational speed detected by the rotation speed detection circuit 11, the duty so they match, and both sets a duty setting circuit for generating a coincidence signal when the match within a scope that is.

Reference numeral 13 denotes a state selection circuit for selecting which position is obtained by dividing one rotation of the DC motor 4 into N (N = 12 in this embodiment) sections. In this embodiment, the state selection circuit 5 is used. Are counted by an N (12) -base counter. Reference numeral 14 measures a cycle in one section, and a target cycle (determined from a target rotation speed).
Is a cycle determination circuit that obtains the value of the correction data from the difference between the two.

Reference numeral 15 denotes connection means that is turned on only when a coincidence signal of the duty setting circuit 12 is generated. 1
Reference numeral 6 denotes N (12) pieces of correction data,
, N,... To N. Reference numeral 17 denotes a limiting circuit for checking the data in the correction data storage means 16 so that each correction data falls within a preset maximum value / minimum value, and corrects the correction data if it exceeds the range.

Reference numeral 18 denotes an input selecting means for selecting correction data to be stored next. Reference numeral 19 denotes output selection means for selecting correction data to be output next. Input selection means 18,
The selection of the output selection means 19 is switched by the output of the state selection circuit 13.

Reference numeral 20 denotes an output of the duty setting circuit 12,
This is a duty correction circuit that corrects according to the correction data selected by the output selection means 19. The output of the duty correction circuit 20 is input to the chopping signal generation circuit 7, and the chopping duty is determined.

The operation of the DC motor operation control device configured as described above will be described with reference to FIGS.

FIG. 2 is a flowchart in one embodiment of the present invention.

In STEP 1, the duty setting circuit 12 compares the rotation speed set by the rotation speed setting circuit 10 with the actual rotation speed detected by the rotation speed detection circuit 11. ST
If the rotation speeds do not match in EP1, STEP
In step 2, the duty is adjusted based on the difference between the rotation speeds . Here, when the actual rotation speed> the set rotation speed, the duty is decreased, and when the actual rotation speed <the set rotation speed, the duty is increased. At this time, since the rotational speed does not match, the connection means 15 does not perform the set of compensation data as an off.

[0030] STEP1 when the speed is match <br/> one within a range set measures the period of interval i represented by state selection circuits 1 3 (STEP3).

Next, the cycle measured in STEP 3 is compared with the target cycle (calculated from the target rotation speed) by the cycle determination circuit 14 (STEP 4). When do not match the period in STEP4, determined correction data at a period determination circuit 14
Therefore, the correction data i of the correction data storage circuit 16 selected by the input selection means 18 is set (STEP 5).

Next, in STEP 6, the limiting circuit 17 determines whether or not the correction data 1 to N are within the preset maximum and minimum values.
The correction data is corrected in P7.

Next, in step 8, the correction data i + 1 selected by the output selection means 19 is output to the duty correction circuit 20 as correction data in the next section i + 1.

Next, in step 9, the state selection circuit 13 counts up to the next section. However, when the counted up value becomes larger than N, i is initialized (i = 1) (STEP10, STEP11).

The operation will be described in detail with reference to FIG.

FIG. 3 is a time chart in the embodiment of the present invention.

FIG. 3A shows the behavior of the compressor during one rotation. TL indicates a change in load torque during one rotation of the compressor, and TM indicates a motor torque generated by the DC motor 4. Further, ω1 represents the variation of the angular velocity in the present embodiment,
ω2 indicates a change in angular velocity at a constant duty.

(B) is a position detection signal of the position detection circuit 5. (C) is a rotation pulse of the position detection circuit 5, and a pulse is generated at the rising / falling edge of each position detection signal shown in (b).

(D) shows correction data output from the correction data storage circuit through the output selection means 19. (E)
Indicates the input of the duty correction circuit 20, and the solid line indicates the output of the duty correction circuit 20, respectively.

The required torque TL of the compressor fluctuates according to the process (suction / compression / discharge). However, when the motor is operated at a constant duty, the motor torque TM is constant, so that the angular velocity is accelerated in the section of TM> TL, and the angular velocity is reduced in the section of TM <TL. As a result, a large speed fluctuation occurs as shown by the angular speed ω2.

When the value output from the duty setting circuit 12 is operated with the duty (solid line portion of (e)) corrected by the correction data shown in (d), the variation of the angular velocity becomes as shown by ω1 in (a). Speed fluctuations are greatly reduced.

As described above, in one embodiment of the present invention, the position detection circuit 5 which detects the position of the rotor of the DC motor 4 and generates a rotation pulse ,
A rotation number detection circuit 11 that counts rotation pulses for a certain period of time
And the set rotation speed and the actual speed detected by the rotation speed detection circuit 11.
From the difference in the number of rotations, the duty is set so that they match.
When both are adjusted and they match within the set range
And a duty setting circuit 12 for generating a match signal
A period determination circuit 14 that divides the DC motor 4 into N sections per rotation by a rotation pulse of the detection circuit 5 , measures the cycle of each section, and generates correction data based on a difference from a target cycle.
A correction data storage circuit 16 for storing the correction data output of the cycle determination circuit 14 for each section; a state selection circuit 13 for selecting the correction data; and a duty correction circuit for correcting the chopping duty based on the selected correction data. 20 and the period is measured for each section,
The displacement with respect to the target cycle calculated from the target rotation speed is obtained, and the correction amount to be performed in the next section is obtained according to the result. By doing so, by having the data as the correction value from a certain defined duty without unbalance also occurs during or deceleration during acceleration, reducing the speed fluctuation, it possible to reduce the vibration and noise it can.

Further, the correction data of the cycle determination circuit is
Output only when the target rotation speed and the actual rotation speed almost match.
And store it in the correction data storage circuit to determine the cycle.
Cancel when unstable, such as during acceleration or deceleration.
Speed fluctuations because it is performed only when it is stable.
And vibration and noise can be reduced.

Check the correction data and set in advance
Each correction data is within the maximum and minimum values
By providing the limiting circuit 17, the data in the correction data storage circuit is rewritten due to disturbances such as noises, etc., so that the limiting circuit 17 returns the value to almost the correct value, and can quickly converge to the correct value. ,
Speed fluctuations can be suppressed, vibration and noise can be reduced, and a normal state can be quickly restored.

In the embodiment, one rotation is divided into 12 parts, but the same effect can be obtained with other division numbers.

[0046]

As described above, according to the present invention, a position detecting circuit for detecting the position of the rotor of a DC motor and generating a rotation pulse, and counting the rotation pulse of the position detection circuit for a certain period of time.
A rotation speed detection circuit for detecting the set rotation speed and the rotation speed.
Based on the difference between the actual rotation speeds detected by the output circuit,
Adjust the duty so that both are set
When a match is made within the specified range
And setting circuit divides one rotation per N phases of the DC motor by the rotation pulse of the position detection circuit, and the cycle determining circuit for generating correction data from the difference between the period of the measured target period for each section, target The rotation speed and the actual rotation speed are set
Connecting means that is turned on only when the values match within the range, a correction data storage circuit that stores the correction data output of the cycle determination circuit for each section, a state selection circuit that selects correction data, And a duty correction circuit that corrects the chopping duty based on the target cycle.The cycle is measured for each section, the displacement with respect to the target cycle calculated from the target rotation speed is obtained, and the following is determined according to the result. A correction amount to be performed in that section is obtained. That is, N
Since each section has data as a correction value from a predetermined duty, unbalance occurs during acceleration and deceleration, speed fluctuation can be suppressed, and vibration and noise can be reduced.

Check the correction data and set in advance.
Each correction data is within the maximum and minimum values
By adding to the configuration Unisuru limiting circuits, even a case where data of the correction data storage circuit due to disturbance such as noise has changed to write, returned to substantially correct value by the limit circuit converges to quickly correct value As a result, speed fluctuations can be suppressed, vibration and noise can be reduced, and a normal state can be quickly restored.

[Brief description of the drawings]

FIG. 1 is a block diagram of a DC motor operation control device according to an embodiment of the present invention.

FIG. 2 is a flowchart according to an embodiment of the present invention.

FIG. 3 is a time chart according to an embodiment of the present invention.

[Explanation of symbols]

2 Rectifier circuit 3 Inverter circuit 4 DC motor 5 Position detection circuit 6 Commutation circuit 7 Chopping signal generation circuit 8 Synthesis circuit 9 Drive circuit 11 Revolution detection circuit 12 Duty setting circuit 14 Period determination circuit 15 Connection means 16 Correction data storage circuit 17 Limiting circuit 20 Duty correction circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-218382 (JP, A) JP-A-2-46173 (JP, A) JP-A-2-179297 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H02P 6/10

Claims (2)

(57) [Claims] A rectifier circuit for converting an AC input into a DC;
An inverter circuit in which a plurality of semiconductor switches and diodes are bridge-connected; a DC motor operated by the inverter circuit; a position detection circuit that detects a position of a rotor of the DC motor and generates a rotation pulse; and the position detection circuit. A commutation circuit that determines the operation of the semiconductor switching element of the inverter circuit based on the output of the inverter circuit, a chopping signal generation circuit that generates a signal for performing chopping for changing the rotation speed of the DC motor, A synthesizing circuit for synthesizing an output of the commutation circuit and an output of the chopping signal generation circuit, a drive circuit for turning on / off a semiconductor switch of the inverter circuit by an output of the synthesizing circuit, and a rotation pulse of the position detection circuit. one
Number of rotations detection circuit that counts for a fixed time
From the difference between the actual rotation speeds detected by the rotation speed detection circuit,
Adjust the duty so that both match, and
Generates a match signal when matches within the set range
A duty setting circuit; a period determination circuit that divides the DC motor into N sections per rotation by a rotation pulse of the position detection circuit, measures a cycle of each section, and generates correction data based on a difference from a target cycle. , Target speed and actual times
Connection that turns on only when the number of turns matches within the set range
Connection means, a correction data storage circuit for storing the correction data output of the cycle determination circuit for each section, a state selection circuit for selecting the correction data, and a duty correction for correcting the chopping duty based on the selected correction data. An operation control device for a DC motor having a circuit. 2. Correction data is checked, and preset
Make sure that each correction data is within the maximum and minimum values
2. The operation of the DC motor according to claim 1, further comprising a limiting circuit for performing the operation.
Control device.