JP2006141107A - Motor control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control system which can reconcile the improvement of accuracy in detection of lock of a motor and the smoothness of motor action. <P>SOLUTION: A motor 1 is PWM-controlled, and motor pulses are outputted from a revolution detection means 4. The motor pulses are input into a frequency sampling part 7, and the frequency is computed by a lock detection data sampling part 7a and a revolution control data sampling part 7b which are different in the number of sampling pieces. The sampling part 7a is fewer in the number of sampling pieces than 7b, and it reacts sharply to motor lock. The first and second control Duty computers 8 and 9 compute the first and second control Duties D1 and D2, based on the frequency data Fa and Fb acquired by both sampling parts 7a and 7b. D1 and D2 are compared with each other in a control Duty comparator 10, and in case that D1<D2, it determines that lock has occurred and controls the motor 1, based on D1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control technology for a motor used in a wiper system of an automobile, and more particularly to a motor control system capable of achieving both improvement in motor lock detection accuracy and smooth motor operation.

  2. Description of the Related Art Conventionally, electromagnetic motors used as drive sources for automobile wiper systems and the like employ various lock detection methods to prevent overcurrent due to lock. For example, the motor control device disclosed in Patent Document 1 discloses a method of determining a locked state when a motor energization current exceeds a predetermined threshold in a power window motor. Here, an average value of current values sampled at a predetermined time interval is used as the motor energization current value, and the presence or absence of lock is determined by comparing this with a preset threshold value for lock detection.

Further, in a motor that outputs a pulse signal in conjunction with a rotation operation, motor speed control and lock detection are performed using the frequency of the output pulse. In this case as well, a moving average value by a predetermined number of pulses is used as the pulse frequency, and when this average value falls below a predetermined threshold value (when the pulse interval is opened and the frequency is reduced), it is determined that the motor is locked. is doing.
JP-A-8-251982

  However, in such a lock detection method, if the current value or the number of pulse samplings is increased, stable control is possible, but there is a problem that the lock detection accuracy is lowered. In other words, if the number of samples is large, the influence of noise components in the average value is reduced, and erroneous control due to abnormal values can be suppressed. On the other hand, the lock judgment interval becomes longer and the change in the sample value becomes smaller. Tend to.

  On the other hand, if the current value or the number of pulse samplings is reduced in order to increase the detection accuracy, the locked state can be detected more quickly, but it becomes easier to react to noise components and the smoothness of motor operation is impaired. Occurs. In other words, if the number of samples is small, the lock judgment interval is short and the change in frequency is reflected sharply in the average value, so lock detection is quick, but it is susceptible to noise and lacks smooth motor operation. There is a case.

  That is, if the influence of noise is suppressed to make the motor operation smooth, the lock detection is delayed, and if the lock detection is advanced, the smoothness of the motor operation is impaired due to the influence of noise. For this reason, depending on the characteristics and usage conditions of the motor, priority must be given to either the motor operation or the lock detection in a contradictory situation, and improvement has been demanded.

  An object of the present invention is to provide a motor control system capable of achieving both improvement in motor lock detection accuracy and smooth motor operation.

  The motor control system of the present invention applies a voltage having a pulse waveform having an ON period and an OFF period, and rotates the motor to effectively change the applied voltage by changing the ON / OFF ratio of the voltage. A motor control system for performing control, wherein a first sampling means for calculating first rotational speed information related to the rotational speed of the motor based on a predetermined first sampling standard, and a predetermined different from the first sampling standard Second sampling means for calculating second rotation speed information related to the rotation speed of the motor based on a second sampling standard, and an ON period of the voltage applied to the motor based on the first rotation speed information First control duty calculation means for calculating a ratio, and second control duty calculation for calculating a ratio during the ON period of the voltage applied to the motor based on the second rotation speed information Means, control duty comparison means for comparing the first control duty value calculated by the first control duty calculation means and the second control duty value calculated by the second control duty calculation means, and the control duty Drive control means for selecting one of the first and second control duty values based on the comparison result in the comparison means and controlling the rotation of the motor.

  In the motor control system, in a motor in which so-called PWM control is executed, two PWM duty values are calculated based on two types of rotation speed information with different sampling standards, and as a result of comparison between the two, Rotation control of the motor is performed by selecting a duty value that matches the current motor status. For this reason, when the motor is locked, it is possible to set the duty value using a sampling standard that can detect it quickly, and during normal operation, it is possible to set the duty value using a sampling standard that is less disturbed by noise. . Accordingly, it is possible to achieve both quick locking and stable motor drive control, and it is possible to improve motor lock detection accuracy and to perform smooth motor operation control.

  In the motor control system, a rotation speed detection unit that outputs a pulse signal as the motor rotates is provided, and at least two pulses of the pulse signal are used by the first sampling unit. A frequency is calculated, first frequency data is formed as the first rotation speed information based on the frequency, and a larger number of pulses of the pulse signal than the first rotation speed information are used by the second sampling means. The frequency of the pulse signal is calculated, second frequency data is formed as the second rotation speed information based on the frequency, and the first control duty calculation means calculates the first frequency based on the first frequency data. A control duty value is calculated, and the second control duty value calculation means calculates the second control duty value based on the second frequency data; When the first control duty value is smaller than the second control duty value, the drive control means may select the first control duty value and control the rotation of the motor. In this case, when the first control duty value is greater than or equal to the second control duty value, the drive control means may select the second control duty value and perform rotation control of the motor. .

  Another motor control system of the present invention applies a voltage having a pulse-like waveform having an ON period and an OFF period, and changes the ON / OFF ratio of the voltage to effectively change the applied voltage. And a first sampling means for calculating first rotational speed information related to the rotational speed of the motor based on a predetermined first sampling standard, and the first sampling standard is different from the first sampling standard. Based on a predetermined second sampling standard, a second sampling means for calculating second rotational speed information related to the rotational speed of the motor, and a threshold comparison for comparing the first rotational speed information with a predetermined threshold value set in advance. And the voltage applied to the motor by selecting one of the first and second rotational speed information based on the comparison result in the threshold value comparing means and the threshold value comparing means Set the ON period time ratio, and having a drive control means for controlling the rotation of the motor.

  In the motor control system, in a motor in which so-called PWM control is executed, two types of rotation speed information with different sampling standards are acquired, and as a result of comparing one of them with a predetermined threshold, the current motor Rotation control of the motor is performed by selecting the duty value that matches the situation. For this reason, when detecting motor lock, the duty value is set by comparing the rotation speed information using the sampling standard that can detect it quickly and the threshold value for lock determination, and sampling with less disturbance due to noise during normal operation It becomes possible to set the duty value based on the rotation speed information using the reference. Accordingly, it is possible to achieve both quick locking and stable motor drive control, and it is possible to improve motor lock detection accuracy and to perform smooth motor operation control.

  In the motor control system, when the first rotation speed information is smaller than the threshold value, the drive control means selects the first rotation speed information and sets the ON period ratio of the voltage. Also good.

  According to the motor control system of the present invention, in a motor in which so-called PWM control is executed, two PWM duty values are calculated based on two types of rotation speed information with different sampling standards, and the result of comparison between the two values. Since the rotation control of the motor is performed by selecting the duty value that matches the current motor status, when the motor is locked, the duty value is set using a sampling standard that can be detected quickly, and during normal operation, the noise is set. It is possible to set the Duty value by using a sampling standard with less disturbance by. Accordingly, it is possible to achieve both quick locking and stable motor drive control, and it is possible to improve motor lock detection accuracy and to perform smooth motor operation control.

  According to another motor control system of the present invention, in a motor in which so-called PWM control is executed, two types of rotation speed information with different sampling standards are acquired, and as a result of comparing one of them with a predetermined threshold value, Since the motor rotation control is performed by selecting the duty value that matches the current motor status, when detecting the motor lock, the rotation speed information using the sampling standard that can detect it quickly and the threshold value for lock determination In comparison, the duty value is set, and during normal operation, the duty value can be set based on rotation speed information using a sampling standard with less disturbance due to noise. Accordingly, it is possible to achieve both quick locking and stable motor drive control, and it is possible to improve motor lock detection accuracy and to perform smooth motor operation control.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of a motor control system that is Embodiment 1 of the present invention. The motor 1 is used as a drive source for a wiper system of an automobile, and power is supplied from a battery 2. The motor 1 is driven and controlled by the motor control system of FIG. 1 having a CPU 3, a rotation speed detection means 4 and a ROM 11.

  The motor 1 is provided with a rotation speed detecting means 4 using a Hall IC. From the rotation speed detection means 4, a pulse signal is output as the motor 1 rotates and sent to the CPU 3. The CPU 3 calculates the frequency (motor rotation frequency) of the transmitted pulse signal, and detects the rotation speed and rotation state of the motor 1 from the calculated value.

  The CPU 3 is provided with a motor drive control unit (drive control means) 5 that performs feedback control of the motor 1 based on the motor rotation frequency. For the motor 1, PWM control (Pulse Width Modulation) that performs drive control by changing the ON / OFF ratio of the pulse width of the applied voltage is executed, and is applied by turning the power supply voltage ON / OFF. The amount of current supplied to the motor 1 is controlled by effectively changing the voltage. In PWM control, the motor drive control unit 5 sets a duty ratio (Duty) of the ON period of the pulse voltage and sends a control signal to the drive output circuit 6. In response to this control signal, the drive output circuit 6 applies a set duty pulse voltage to the motor 1, whereby the rotational speed of the motor 1 is appropriately controlled.

  On the other hand, the CPU 3 is provided with a frequency sampling unit 7 that samples a predetermined number of motor rotation frequencies and obtains a moving average value thereof. The frequency sampling unit 7 is connected to the rotation speed detection means 4, and a pulse signal (motor pulse) is input from the rotation speed detection means 4 as the motor 1 rotates. In the frequency sampling unit 7, a lock detection data sampling unit (first sampling means) 7a for generating lock detection frequency data and a rotation control data sampling unit (second sampling unit) for generating normal control frequency data are provided. (Sampling means) 7b is provided (hereinafter, the data sampling units 7a and 7b are abbreviated as sampling unit 7a and sampling unit 7b).

  Both sampling units 7a and 7b have different filter lengths during data sampling. Here, the filter length of the sampling unit 7b is set to be longer, and the number of pulses used (number of pulse samplings) at the time of creating the frequency data is larger in the sampling unit 7b. Each sampling unit 7a, 7b takes a preset number of pulses from the pulse signal output from the rotational speed detection means 4 (for example, 7a: 2 pieces, 7b: 12 pieces) and calculates an average value thereof. The frequency data Fa and Fb are created. The frequency data Fa means data created by the sampling unit 7a and is first frequency data (first rotation speed information). The frequency data Fb means data created by the sampling unit 7b and is second frequency data (second rotation speed information). For the frequency data Fa and Fb, moving average values calculated while shifting the pulses one by one are used.

  A first control duty calculation unit (first control duty calculation means) 8 that calculates a PWM duty value used for lock detection from the frequency data for lock detection is provided at the subsequent stage of the sampling unit 7a. The first control duty calculation unit 8 acquires frequency data for lock detection with a short filter length from the sampling unit 7a, and refers to a control map 12 stored in a ROM (storage means) 11 for lock detection. The first control duty value D1 is calculated.

  The control map 12 is provided with a Max. Duty map (FIG. 6) set from the viewpoint of preventing demagnetization of the magnet and the current capacity of the switching element in order to suppress the current amount at the time of locking. The Max. Duty map is obtained by multiplying the Max. Duty value (D0) when the motor 1 is in the locked state (motor rotational frequency = 0) and a predetermined coefficient using the frequency as a parameter. Stores the duty corresponding frequency value. The first control duty calculation unit 8 sets D1 with reference to this Max. Duty map based on the frequency data acquired from the sampling unit 7a.

  A second control duty calculation unit 9 (second control duty calculation unit) that calculates a PWM duty value for normal control from frequency data for rotation control is provided at the subsequent stage of the sampling unit 7b. The first control duty calculation unit 9 obtains frequency data for normal control having a long filter length from the sampling unit 7b, and refers to the Max. Duty map provided in the control map 12 to obtain the second control duty. The value D2 is calculated.

  A control duty comparison unit (control duty comparison means) 10 is provided following the first and second control duty calculation units 8 and 9. The control duty comparison unit 10 acquires the first and second control duty values D1 and D2 from the first and second control duty calculation units 8 and 9, and compares the magnitudes of the two. As a result of the determination process described later, when it is determined that a lock has occurred, the control duty comparison unit 10 instructs the motor drive control unit 5 to set the PWM duty value to D1 or less. On the other hand, when it is determined that the lock state is not established, the motor drive control unit 5 is instructed to set the PWM duty value to D2.

  FIG. 2 is a flowchart showing a control processing procedure in the control system of FIG. The control process of FIG. 2 is started when the ignition key of the automobile is turned on. First, the frequency data Fa is calculated by the sampling unit 7a having a short filter length (small sampling number) (step S1). After calculating the frequency data Fa, the process proceeds to step S2, and the first control duty calculation unit 8 obtains the first control duty value D1. The first control duty calculation unit 8 calculates the first control duty value D1 with reference to the control map 12 based on the frequency data Fa.

  After calculating D1, the process proceeds to step S3, where the frequency data Fb is calculated by the sampling unit 7b having a long filter length (a large number of samplings). After calculating the frequency data Fb, the process proceeds to step S4, and the second control duty value calculation unit 9 obtains the second control duty value D2. The second control duty calculation unit 9 refers to the control map 12 and calculates the second control duty value D2 based on the frequency data Fb. Note that either the processing of steps S1 and S2 and the processing of steps S3 and S4 may be performed first, or both processing may be performed in parallel.

  After obtaining the first and second control duty values D1, D2, the process proceeds to step S5, where the control duty comparison unit 10 compares the two duty values D1, D2. Here, when the motor 1 approaches the locked state, the motor rotation frequency rapidly decreases, and the effect appears quickly in the frequency data with a short filter length. FIG. 3 is a table showing the relationship between the passage of time and frequency data for each pulse sampling number, FIG. 4 is a graph showing the table of FIG. 3 in a diagram, and FIG. 5 is a motor pulse, current value, motor torque, It is a graph which shows the relationship.

  In FIGS. 3 and 4, for example, when “320 Hz” is used as a threshold value as a reference for lowering the motor rotation speed and a motor rotation frequency with a smaller value is detected, when the number of pulse sampling is 2, At point A, the motor rotation frequency is 312 Hz, which can be detected at 0.2028 seconds. On the other hand, when the number of pulse samplings is 12, the motor rotation frequency is 429 Hz (difference to the threshold: 117 Hz) at point A, and a decrease in the motor rotation number cannot be detected. In this case, it can be detected for the first time at 0.2269 seconds (point B), and there is a time difference of 0.0241 seconds between them. Similarly, the motor rotation frequency is less than 320 Hz when the number of pulse samplings is 3 or 4 at 0.2067 seconds, and when it is 6 at 0.2114 seconds. That is, the frequency data is more sensitive to changes in the motor rotation speed as the number of pulse samplings is smaller, and the motor lock can be detected earlier when the number of samplings is smaller.

  On the other hand, as shown in FIG. 5, the motor current amount increases during 0.0241 seconds from A to B. The current amount is 23 A or less at point A, but increases to about 32 A at point B. In this case, if the allowable current amount of the motor 1 is, for example, 30A, the current amount of the motor 1 can be sufficiently suppressed to 30A or less if the lock is detected at point A and the duty is suppressed. However, if the lock is detected at point B, the current amount has already exceeded 30 A, and the motor current cannot be suppressed below the allowable value. When the number of pulse samplings is 12, when trying to detect lock at point A, it is necessary to determine that lock is detected when the motor rotation frequency is 430 Hz, and the duty must be suppressed from a higher frequency. The controllable region is narrowed, and the degree of freedom of control is reduced.

  In the Max. Duty map, the Max. Duty value decreases as the frequency decreases. FIG. 6 is an explanatory diagram showing an example of the Max. Duty map. The Max. Duty map of FIG. 6 is stored in the ROM 11, and when the motor 1 is locked and the motor rotation frequency becomes 0 Hz, the maximum duty value is suppressed to 60 to 80% according to the power supply voltage value. ing. For example, when the motor 1 is locked when the power supply voltage exceeds 13.5 V and is 14.0 V or less, the maximum value of Duty is reduced to 65%.

  In a scene where the motor rotation speed rapidly decreases, the Max. Duty value also decreases as the motor rotation frequency decreases. At this time, D1 becomes smaller than D2 from the pulse sampling number. For example, in the above example, if the power supply voltage exceeds 13.5 V and is 14.0 V or less, D1 at point A is 88 Hz and D2 is 95 Hz as shown in FIG. 6, and D1 is smaller than D2. Therefore, in step S5, when D1 becomes smaller than D2 (D1 <D2), the control duty comparison unit 10 determines that a lock has occurred, and proceeds to step S6. In step S6, the PWM duty value of the motor 1 is set to D1 or less regardless of the value of D2. At this time, the motor drive control unit 5 sets the PWM Duty value to D1 or less based on the comparison result of the control duty comparison unit 10 so that an excessive current does not flow to the motor 1 due to the occurrence of lock, and this is indicated in the drive output circuit. 6 is instructed.

  After setting the PWM duty value to be equal to or less than D1, the process proceeds to step S8, where the PWM duty value having D1 as the maximum value is output and the routine is exited. That is, the drive output circuit 6 receives the above instruction and drives the motor 1 with the PWM duty value suppressed to D1 or less. Thereby, the motor 1 is driven in a control mode corresponding to the locked state.

  On the other hand, if D1 is greater than or equal to D2 in step S5 (D1 ≧ D2), the control duty comparison unit 10 determines that no lock has occurred, and proceeds to step S7 to set the PWM duty value to D2. In step S8, D2 is output as the PWM duty value and the routine is exited.

  Thus, in the motor control system of the present invention, the motor rotation frequency is calculated by the two sampling units 7a and 7b having different filter lengths, and the drive control of the motor 1 is performed while comparing the frequency data calculated by both. Do. For this reason, when the motor is locked, it is possible to quickly respond to the lock based on the frequency data of the sampling unit 7a having a short filter length that can be detected quickly. On the other hand, during normal operation, drive control is performed based on the frequency data of the sampling unit 7b having a long filter length, so that the frequency data is less likely to be disturbed by noise, and stable motor drive control is possible. Therefore, according to the motor control system, the motor lock detection accuracy can be improved, and smooth motor operation control can be performed.

  Note that the difference between the values of D1 and D2 is taken in step S5, and if the value exceeds a predetermined value, it may be determined that a lock has occurred. By performing control using the difference between D1 and D2, even when D1 is specifically reduced due to the influence of noise or the like, the lock determination is retained. That is, even if some disturbance occurs in D1, it is not immediately determined that a lock has occurred, and the influence of noise can be avoided, and more stable drive control can be achieved.

  In the above example, D1 and D2 are obtained from the same map, but D1 may be obtained from a lock detection map and D2 may be obtained from a normal control map provided separately from D1. Furthermore, D1 and D2 may be obtained using an arithmetic expression instead of a map.

  FIG. 7 is a block diagram showing a configuration of a motor control system that is Embodiment 2 of the present invention. In the system of FIG. 7, instead of comparing the duty values in the first embodiment, the frequency data Fa and Fb are directly used, and the lock determination is performed by comparison with the threshold value. In the following embodiments, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the system of FIG. 7, a lock detection unit (threshold comparison means) 13 is provided after the sampling unit 7b. The lock detection unit 13 compares the threshold value Fs, which is a lock detection frequency stored in the ROM 11, with the frequency data Fb. As the threshold value Fs, a frequency that can be regarded as occurrence of lock as viewed from the frequency data Fa is set. The lock current can be kept below the maximum allowable current.

  FIG. 8 is a flowchart showing a control processing procedure in the control system of FIG. The control process of FIG. 7 is also started when the ignition key of the automobile is turned on. First, the frequency data Fa is calculated by the sampling unit 7a having a short filter length (step S11). Next, in step S12, the frequency data Fb is calculated by the sampling unit 7b having a long filter length. Either of the processes in steps S11 and S12 may be performed first, or both processes may be performed in parallel.

  After calculating the frequency data Fa and Fb, the process proceeds to step S13, and the lock detection unit 13 compares the frequency data Fa with the threshold value Fs. At this time, if Fa becomes less than Fs (Fa <Fs), it is determined that a lock has occurred, and the process proceeds to step S14. In step S14, PWM Duty is set based on Fa with reference to the Max. Duty map of FIG. That is, the motor drive control unit 5 refers to the control map 12 in the ROM 11 and sets the Max. Duty value corresponding to the locked state.

  Looking at these processes in the example of the first embodiment, for example, if the threshold value Fs is set to 320 Hz, it is determined that a lock has occurred when Fa becomes less than 320 Hz (at least point A) (step S13). Regardless of the value of Fb at that time, the Max. Duty map is referred to based on Fa, and Max. Duty is set to 88 Hz (step S14). At this time, Fb is 429 Hz, the threshold value Fs has not been reached, and the occurrence of lock cannot be detected with Fb alone.

  After setting Max. Duty in this way, the process proceeds to step S15, where a PWM Duty value having the maximum value is output and the routine is exited. As a result, the drive output circuit 6 keeps the PWM duty value below the set Max. Duty value and drives the motor 1 in a control mode corresponding to the locked state.

  On the other hand, if Fa is greater than or equal to Fs in step S13 (Fa ≧ Fs), it is determined that no lock has occurred, and the process proceeds to step S16. In step S14, the PWM duty is set based on Fb with reference to the Max. Duty map of FIG. In this case, the control map may be properly used for Fb and Fa. After setting the PWM duty value in step S14, the process proceeds to step S15 to output the value and exit the routine.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, an example in which the present invention is applied to a motor for a wiper system of an automobile has been shown. The present invention can be applied to various motors such as on-vehicle motors and motors used in pumps used in cold regions. Further, the numerical values given in the above-described embodiment and the table of FIG. 6 are merely examples, and it goes without saying that the present invention is not limited to these numerical values.

  Furthermore, in the above-described embodiment, an example in which the lock detection process is performed using the motor rotation frequency is shown. However, for example, an analog value of the rotation speed can be used as long as the method can detect a decrease in the motor rotation speed. . In this case, the length of the filter is the length of the sampling time, and the sampling unit 7a uses the moving average value of the motor rotation speed in a short time.

It is a block diagram which shows the structure of the motor control system which is Example 1 of this invention. It is a flowchart which shows the control processing procedure in the control system of FIG. It is the table | surface which showed the relationship between time passage and frequency data for every pulse sampling number. It is the graph which showed the table | surface of FIG. 3 with the diagram. It is a graph which shows the relationship between a motor pulse, an electric current value, and a motor torque. It is explanatory drawing which shows an example of a Max. Duty map. It is a block diagram which shows the structure of the motor control system which is Example 2 of this invention. It is a flowchart which shows the control processing procedure in the control system of FIG.

Explanation of symbols

1 Motor 2 Battery 3 CPU
4 Rotational speed detection means 5 Motor drive control section (drive control means)
6 Drive output circuit 7 Frequency sampling unit 7a Data sampling unit for lock detection (first sampling means)
7b Data sampling section for rotation control (second sampling means)
8 1st control duty calculation part (1st control duty calculation means)
9 Second control duty calculation unit (second control duty calculation means)
10 Control Duty Comparison Unit (Control Duty Comparison Unit)
11 ROM
12 Control map 13 Lock detection part (threshold comparison means)
D1 First control duty value D2 Second control duty value Fa Frequency data (first frequency data; first rotation speed information)
Fb frequency data (second frequency data; second rotation speed information)
Fs threshold

Claims (5)

A motor control system that performs rotation control of a motor that effectively changes the applied voltage by applying a voltage having a pulsed waveform with an ON period and an OFF period and changing the ON / OFF ratio of the voltage. And
First sampling means for calculating first rotational speed information relating to the rotational speed of the motor based on a predetermined first sampling criterion;
Second sampling means for calculating second rotational speed information relating to the rotational speed of the motor based on a predetermined second sampling standard different from the first sampling standard;
First control duty calculation means for calculating an ON period ratio of the voltage applied to the motor based on the first rotation speed information;
Second control duty calculation means for calculating an ON period ratio of the voltage applied to the motor based on the second rotation speed information;
Control duty comparison means for comparing the first control duty value calculated by the first control duty calculation means with the second control duty value calculated by the second control duty calculation means;
Motor control, comprising: drive control means for selecting one of the first and second control duty values based on a comparison result in the control duty comparison means and performing rotation control of the motor. system. The motor control system according to claim 1,
While providing a rotation speed detection means for outputting a pulse signal with the rotation of the motor,
The first sampling means calculates a frequency of the pulse signal using at least two pulses of the pulse signal, and forms first frequency data as the first rotation speed information based on the frequency. ,
The second sampling means calculates a frequency of the pulse signal using a larger number of pulses of the pulse signal than the first rotation speed information, and based on the frequency, as the second rotation speed information, Form two frequency data,
The first control duty calculation means calculates the first control duty value based on the first frequency data,
The second control duty calculation means calculates the second control duty value based on the second frequency data,
When the first control duty value is smaller than the second control duty value, the drive control means selects the first control duty value and controls the rotation of the motor. .   3. The motor control system according to claim 2, wherein when the first control duty value is greater than or equal to the second control duty value, the drive control means selects the second control duty value to control rotation of the motor. A motor control system characterized by A motor control system that performs rotation control of a motor that effectively changes the applied voltage by applying a voltage having a pulsed waveform with an ON period and an OFF period and changing the ON / OFF ratio of the voltage. And
First sampling means for calculating first rotational speed information relating to the rotational speed of the motor based on a predetermined first sampling criterion;
Second sampling means for calculating second rotational speed information relating to the rotational speed of the motor based on a predetermined second sampling standard different from the first sampling standard;
Threshold comparing means for comparing the first rotational speed information with a predetermined threshold set in advance;
Based on the comparison result in the threshold value comparison means, either one of the first and second rotation speed information is selected and an ON period ratio of the voltage applied to the motor is set, and the rotation of the motor A motor control system comprising drive control means for performing control.   5. The motor control system according to claim 4, wherein, when the first rotation speed information is smaller than the threshold value, the drive control unit selects the first rotation speed information and sets the ON period time ratio of the voltage. A motor control system characterized by:

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