JP2004157066A - Method and apparatus for detecting rotation speed of motor - Google Patents

Method and apparatus for detecting rotation speed of motor Download PDF

Info

Publication number
JP2004157066A
JP2004157066A JP2002324929A JP2002324929A JP2004157066A JP 2004157066 A JP2004157066 A JP 2004157066A JP 2002324929 A JP2002324929 A JP 2002324929A JP 2002324929 A JP2002324929 A JP 2002324929A JP 2004157066 A JP2004157066 A JP 2004157066A
Authority
JP
Japan
Prior art keywords
cycle
rotation speed
counting
motor
count value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2002324929A
Other languages
Japanese (ja)
Inventor
Masao Nakada
昌雄 中田
Original Assignee
Asmo Co Ltd
アスモ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Asmo Co Ltd, アスモ株式会社 filed Critical Asmo Co Ltd
Priority to JP2002324929A priority Critical patent/JP2004157066A/en
Publication of JP2004157066A publication Critical patent/JP2004157066A/en
Pending legal-status Critical Current

Links

Images

Abstract

An object of the present invention is to provide a rotation speed detection device and method capable of easily and accurately detecting the rotation speed regardless of the rotation speed of a motor.
In detecting a rotation speed based on a one-cycle count value obtained by counting one cycle of a Hall IC signal which is a pulse signal generated by a Hall IC element according to a rotation angle of a shaft. One half of the above-mentioned Hall IC signal is divided into two, and the period of each divided region is counted as one half of the counting period assuming that the period is counted without dividing one period. The one-cycle count value is derived by summing the count values of the divided regions thus obtained.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation speed of a motor that detects a rotation speed based on a one-cycle count value obtained by counting one cycle of a detection signal that is a pulse signal generated according to a rotation angle of a rotation shaft of the motor. The present invention relates to a detection device and method.
[0002]
[Prior art]
In a motor that rotates and drives a rotating shaft, a rotating speed detecting device detects an actual rotating speed of the rotating shaft, and the rotating speed is used for controlling a rotating speed for driving the motor stably at a desired rotating speed. Used.
[0003]
The rotation speed detection device used at this time has a rotation speed based on a one-cycle count value obtained by counting one cycle of a detection signal which is a pulse signal generated according to the rotation angle of the rotation shaft of the motor. In this case, a Hall IC element, an encoder, or the like is used as a detection element that outputs the detection signal.
[0004]
Here, the motor speed detecting device that calculates the rotation speed of the rotor by using an encoder that outputs a signal of a plurality of phases having a phase difference with the rotation of the rotor as a detection element has a rotation speed of the rotor calculated last time. There is a technique for determining whether the rotation speed is high or low according to whether the rotation speed is high or low compared to a predetermined speed, and switching the calculation method of the rotation speed according to the determination result (for example, see Patent Document 1). .
[0005]
That is, in this technique, if the previously calculated rotation speed of the rotor is lower than the predetermined speed, the cycle is measured for each edge of the multi-phase pulse signal in the current calculation, and the rotor is rotated based on the measured cycle. Calculate the rotation speed. Further, if the previously calculated rotation speed of the rotor is higher than the predetermined speed, a plurality of rotations having a phase difference within that period are performed at predetermined intervals, which is a time sufficient for performing the speed calculation in the current calculation. The edges of the phase pulse signal are counted, and the rotational speed of the rotor is calculated from the counted value. Therefore, accurate speed detection can be performed regardless of whether the rotation speed of the rotor is low or high.
[0006]
On the other hand, in a rotational speed detecting device using a Hall IC element as a detecting element, a plurality of Hall IC elements are fixedly provided around a rotation axis, and a permanent magnet is provided so as to rotate integrally with the rotation axis. In some cases, a change in the magnetic field due to the magnetic pole is detected and a signal as shown in FIG. 7 (hereinafter, referred to as a “Hall IC signal”) is output as an example. One cycle of the Hall IC signal corresponds to a predetermined rotation angle of the rotating shaft, and this kind of rotation speed detecting device uses one cycle of the Hall IC signal as a predetermined counting cycle (hereinafter, referred to as “count cycle”). In some cases, a timer that can count up to a predetermined upper limit value (for example, 255 in the example shown in FIG. 7) for each time is used, and the rotational speed is calculated using the count value.
[0007]
In this technique, as an example, as shown in the following equation (1), a predetermined value ((1)) that is predetermined based on the rotation angle of the rotating shaft corresponding to one cycle of the Hall IC signal and the count cycle by the timer. In the formula, the rotation speed is calculated by dividing '5000') by the count value of one cycle.
[0008]
(Equation 1)
[0009]
Here, it goes without saying that the count value in one cycle increases as the rotation speed of the motor decreases. On the other hand, since the range that can be counted by the timer is limited, the counting cycle when counting one cycle of the Hall IC signal by the timer is a cycle that can sufficiently count one cycle of the Hall IC signal at low speed rotation. It has been.
[0010]
[Patent Document 1]
JP-A-2002-171787
[0011]
[Problems to be solved by the invention]
However, in the technique of calculating the rotation speed of the motor using the output signal of the encoder, it is necessary to switch the calculation method of the rotation speed depending on whether the previously calculated rotation speed is lower or higher than a predetermined speed, and the processing is complicated. , There was a problem.
[0012]
On the other hand, in the technique of calculating the rotation speed of the motor using the Hall IC signal described with reference to FIG. 7, as described above, the count period of the timer is set in accordance with the rotation speed at low speed rotation. Therefore, as shown in Table 1 below, as an example, the calculation result of the rotation speed when the count value has a difference of one count is the same at the time of low-speed rotation, but is large at the time of high-speed rotation. A difference (56 rpm (= 556-500) in the example shown in Table 1) occurs. As is clear from this, the influence on the calculation result of one count by the timer increases as the rotation speed increases.
[0013]
[Table 1]
[0014]
As a result, this technique has a problem that the higher the rotation speed of the motor, the lower the resolution of the rotation speed and the lower the detection accuracy of the rotation speed.
[0015]
The present invention has been made in order to solve the above problems, and has as its object to provide a motor rotation speed detection device and method that can easily and accurately detect the rotation speed regardless of the rotation speed. .
[0016]
[Means for Solving the Problems]
To achieve the above object, an invention according to claim 1 is a one-period meter obtained by counting one period of a detection signal which is a pulse signal generated according to a rotation angle of a rotation shaft of a motor. A motor rotation speed detection device for detecting a rotation speed based on a numerical value, wherein one period of the detection signal is divided into N (N is an integer of 2 or more), and a period of each divided region is divided into one period. Counting means for counting 1 / N of the counting cycle assuming counting without counting, and the one-cycle meter by summing up the count values of the respective divided areas counted by the counting means. Deriving means for deriving a numerical value.
[0017]
According to the first aspect of the present invention, rotation is performed based on a one-cycle count value obtained by counting one cycle of a detection signal which is a pulse signal generated according to the rotation angle of the rotating shaft of the motor. Speed is detected. The detection signal is a signal corresponding to the above-mentioned Hall IC signal or an output signal of the encoder.
[0018]
Here, in the present invention, one period of the detection signal is divided into N by the counting means, and the period of each divided region is 1 / N of the counting period in a case where counting is performed without dividing one period. Is counted as a counting cycle, and the counting value of each divided area is summed up by the deriving means to derive the one-cycle counting value. In addition, as a mode of counting the period of each divided region by the counting means, a mode of counting each divided region by a common counter or a mode of counting each divided region by a different counter for each divided region can be applied.
[0019]
That is, in the present invention, one cycle of the detection signal, which has been counted without being divided in the past, is divided into N, and the period of each divided area is counted at 1 / N of the conventional counting period. The one-cycle count value is derived by summing up the numerical values, thereby increasing the count range of the counting means to N times, thereby suppressing deterioration in the rotational speed resolution due to the limitation of the count range, Regardless of the rotation speed, the detection accuracy of the rotation speed is set to be N times the conventional accuracy.
[0020]
In addition, according to the present invention, there is no need to switch the method of calculating the rotation speed according to the rotation speed, so that the present invention can be easily realized as compared with the conventional technique for performing the switching.
[0021]
As described above, according to the first aspect of the present invention, the one-cycle count value obtained by counting one cycle of the detection signal, which is a pulse signal generated according to the rotation angle of the rotating shaft of the motor, is obtained. When detecting the rotation speed based on the assumption, it is assumed that one cycle of the detection signal is divided into N (N is an integer of 2 or more) and the period of each divided area is counted without dividing one cycle. 1 / N of the counting cycle is counted as the counting cycle, and the one-cycle count value is derived by summing up the counted values of the respective divided areas, so that the rotation speed can be simplified regardless of the rotation speed. And it can detect with high precision.
[0022]
When one period of the detection signal is divided into N and the period of each divided region is counted, the frequency of the detection signal is converted to be appropriately increased using a frequency multiplier circuit or the like, and the above-described signals in the converted signal are converted. The counting can be realized by starting the counting in each of the divided areas in synchronization with the switching timing of the signal level corresponding to the boundary position of the divided area.
[0023]
The detection signal according to the first aspect of the present invention is such that the polarity of the detection signal alternately changes at substantially equal intervals in the rotation direction of the rotation axis due to the rotation of the rotation axis. A signal obtained by detecting a change in the magnetic field caused by the magnetic material provided as described above may be used. That is, in this embodiment, the present invention is applied to a rotation speed detection device using a Hall IC element, and the rotation speed can be easily and accurately detected by the device, regardless of the rotation speed. Can be obtained.
[0024]
By the way, when N of the present invention is set to 2, the counting means divides the signal into two in synchronism with a signal level switching timing within one cycle of the detection signal. By starting the counting of the area, it is possible to easily count the period for each divided area without using the above-described frequency multiplying circuit or the like.
[0025]
On the other hand, the invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the predetermined rotation angle of the rotation shaft and the counting means corresponding to one cycle of the detection signal. Calculates the rotation speed of the motor by dividing the predetermined divided value by the one-cycle count value based on the counting cycle according to the above, and overflows the one-cycle count value beyond a predetermined upper limit value. In this case, there is further provided a calculating means for calculating the rotation speed of the motor assuming that the one-cycle count value and the divided value are divided by a predetermined value.
[0026]
According to a fourth aspect of the present invention, in the first aspect of the present invention, the predetermined rotation angle and the count of the rotation axis corresponding to one cycle of the detection signal are calculated by the arithmetic means. The rotation speed of the motor is calculated by dividing the predetermined divided value by the one-cycle count value based on the counting cycle by the means. That is, in the present invention, the rotation speed of the motor is derived by the calculation means by the calculation involving the division by the one-cycle count value as in the equation (1) exemplified above.
[0027]
In this case, depending on the rotation speed of the motor, the one-cycle count value may overflow the predetermined upper limit value. At this time, the one-cycle count value and the division value are calculated by the arithmetic means of the present invention. The rotation speed of the motor is calculated by dividing the value by a predetermined value.
[0028]
As a result, it is possible to prevent an overflow of the one-cycle count value from occurring, and it is possible to prevent the calculation result of the rotation speed from becoming unstable when the overflow occurs.
[0029]
On the other hand, in order to achieve the above object, an invention according to claim 5 is a method in which one cycle of a detection signal which is a pulse signal generated according to a rotation angle of a rotation shaft of a motor is obtained. A method for detecting a rotation speed of a motor, wherein a rotation speed is detected based on a cycle count value, wherein one cycle of the detection signal is divided into N (N is an integer of 2 or more), and a period for each divided area is defined as one cycle. Is calculated by counting 1 / N of the counting cycle assuming that counting is performed without division, and summing up the counted values of the divided areas to derive the one-cycle count value. is there.
[0030]
Therefore, according to the method of detecting the rotational speed of the motor according to the fifth aspect, the operation is performed in the same manner as in the first aspect of the invention. Speed can be detected easily and with high accuracy.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, an embodiment in which the present invention is applied to a rotation speed detection unit that detects the rotation speed of a brushless motor using a Hall IC element will be described. FIG. 1 shows a partially cutaway side view of a brushless motor 12 including the rotation speed detection unit.
[0032]
As shown in FIG. 1, the brushless motor 12 includes a housing 14, in which a drive unit 16 and a board 18 of a motor control unit 10 that controls driving of the brushless motor 12 are housed.
[0033]
The housing 14 is formed in a shallow bottom substantially box shape with one end opened, and a substantially cylindrical tube portion 34 is provided integrally with the housing 14 at the open end of the housing 14.
[0034]
The housing 14 is provided with a support portion 36 having a substantially cylindrical shape, and a stator 28 as a stator constituting the drive portion 16 is integrally attached to an outer peripheral portion of the support portion 36. The stator 28 has a core 26 formed by laminating a plurality of core pieces made of a thin silicon steel plate or the like. Further, the core 26 has three-phase coils 30U, 30V, and 30W each serving as a winding. Is wound around the coil group 30. These coils 30U to 30W are provided so that the electrical phase is shifted by 120 degrees, and these coils 30U to 30W are alternately energized or de-energized at a predetermined timing, so as to surround stator 28. A predetermined rotating magnetic field is formed.
[0035]
On the other hand, a pair of bearings 38 are fixed inside the support portion 36, and the shafts 20 are coaxially supported by the bearings 38 on the support portion 36 and the cylindrical portion 34 so as to be rotatable around its own axis. Have been.
[0036]
One end of the shaft 20 in the axial direction penetrates the cylindrical portion 34 and is mechanically connected to a driving member (not shown) which is driven at the one end or near the one end by receiving the rotational force of the shaft 20.
[0037]
A rotor 22 as a rotor constituting the drive unit 16 is integrally attached to a portion of the shaft 20 penetrating from the cylindrical portion 34. The rotor 22 is formed in a bottomed cylindrical shape coaxial with the cylindrical portion 34 and the support portion 36 opened in the direction opposite to the opening direction of the housing 14, and the shaft 20 passes through the upper bottom portion of the rotor 22. ing.
[0038]
A substantially cylindrical magnet 24 as a permanent magnet is coaxially fixed to the rotor 22 on the inner periphery of the rotor 22. The magnet 24 is formed so that one side in the radial direction has an N pole and the other side has an S pole via the axis thereof, and the magnet 24 has a magnetic pole at a predetermined angle (for example, 60 degrees) around its axis. Are formed so as to change the polarity, and a predetermined magnetic field is formed therearound.
[0039]
The magnet 24 is provided so as to face the stator 28 outside the stator 28 along the radial direction of the support portion 36. When the above-described coil group 30 is energized and a rotating magnetic field is formed around the stator 28, An interaction between the rotating magnetic field and the magnetic field formed by the magnet 24 generates a rotational force around the support portion 36 on the magnet 24, thereby rotating the shaft 20.
[0040]
On the other hand, on the bottom side of the housing 14 with respect to the stator 28, a board 18 as the motor control unit 10 is arranged. Printed wiring is provided on at least one of the front surface and the back surface of the substrate 18, and a plurality of resistance elements, transistor elements, and elements such as a microcomputer are appropriately connected via the above-described printed wiring.
[0041]
FIG. 2 is a block diagram of a portion related to driving of the brushless motor 12. Note that, in the figure, circuits, elements, and the like other than the coil 30 constitute a part of the motor control unit 10.
[0042]
The coil 30 is connected to a three-phase inverter 54 that rectifies the current flowing through the coils 30U to 30W of the brushless motor 12, and power is supplied from a power source 60 for driving the brushless motor 12 via the three-phase inverter 54.
[0043]
The three-phase inverter 54 includes field effect transistors (hereinafter, referred to as “MOSFETs”) 78U, 78V, 78W, 80U, 80V, 80W as switching elements. The source terminal of MOSFET 78U and the drain terminal of MOSFET 80U are connected to the terminal of coil 30U, the source terminal of MOSFET 78V and the drain terminal of MOSFET 80V are connected to the terminal of coil 30V, and the source terminal of MOSFET 78W and the drain terminal of MOSFET 80W are It is connected to the terminal of the coil 30W.
[0044]
The pre-driver circuit 52 that outputs a switching signal for rotating the brushless motor 12 at a predetermined speed is connected to the three-phase inverter 54. The booster circuit 56 is connected to the pre-driver circuit 52, and the output voltage level of the pre-driver circuit 52 can be higher than the voltage level of the power supply 60.
[0045]
The pre-driver circuit 52 is connected to the gate terminals of the MOSFETs 78U to W and 80U to W, and inputs a switching signal (“LOW” or “HIGH”) to the gate terminals of the MOSFETs 78U to 78W and 80U to 80W.
[0046]
The MOSFETs 78U to 78W and 80U to 80W are basically in an "OFF" state when a "LOW" level switching signal is input to the gate terminal, and basically no current from the power supply 60 flows from the drain terminal to the source terminal. On the other hand, the MOSFETs 78U to 78W and 80U to 80W become "ON" when a "HIGH" level switching signal is input to the gate terminal, and the current from the power supply 60 flows from the drain terminal to the source terminal.
[0047]
On the other hand, FIG. 3 shows a block diagram of a portion related to a rotation speed detecting function in the motor control unit 10.
[0048]
As shown in the figure, the motor control unit 10 includes the above-described pre-driver circuit 52, a CPU (Central Processing Unit) 50 that controls the operation of the entire device, and a rotation speed detection unit 62. .
[0049]
An operation unit 58 for operating a driving member (not shown) is connected to the CPU 50. The CPU 50 sets the rotation speed of the brushless motor 12 based on an operation signal from the operation unit 58, The rotation operation of the rotor 22 is controlled.
[0050]
Here, a sensor magnet 76 coaxially and integrally fixed to the shaft 20 of the brushless motor 12 according to the present embodiment (see FIG. 1 and FIG. (Omitted). The sensor magnet 76 is a permanent magnet, and is a multi-pole magnet in which N poles and S poles are alternately positioned at predetermined angles around the axis of the sensor magnet 76, and forms a specific magnetic field around the magnet.
[0051]
Outside the sensor magnet 76 in the radial direction, Hall IC elements 44U, 44V, and 44W are provided on the substrate 18 and at every 120 degrees around the axis of the sensor magnet 76. The Hall IC elements 44U to 44W are connected to the rotation speed detection unit 62, and detect changes in the magnetic field at the respective arrangement positions due to the rotation of the sensor magnet 76, and output the detection results as Hall IC signals Hu, Hv, Hw. (See also FIG. 5) is output to the rotation speed detection unit 62.
[0052]
The rotation speed detecting unit 62 can count (count) the count processing unit 68 up to a predetermined upper limit value (255 in the present embodiment) at a predetermined cycle (0.5 ms in the present embodiment). , Timers 64 and 66, a memory 70, and an arithmetic processing unit 72.
[0053]
The count processing unit 68 counts a period of each one of the Hall IC signals Hu, Hv, and Hw using a timer 64 and a timer 66 as a detection period T using one timer. In the brushless motor 12 according to the present embodiment, the Hall IC signal Hu is applied as a signal to be counted. That is, the brushless motor 12 according to the present embodiment is configured to detect the rotation speed based on the count value of the Hall IC signal Hu in each period of the detection cycle T. It is needless to say that another Hall IC signal may be used for detecting the rotation speed, or a combination of a plurality of Hall IC signals may be used.
[0054]
FIG. 5 shows an example of a waveform diagram showing the relationship between the Hall IC signal Hu and the output signals of the timers 64 and 66.
[0055]
As shown in the figure, the rotation speed detection unit 62 according to the present embodiment divides the detection cycle T of the Hall IC signal Hu into two in accordance with the signal level and divides the detection cycle T into a “HIGH” level period (hereinafter “HIGH”). The term “period”) is counted by the timer 64 as the first half of the detection period T, and the period at the “LOW” level (hereinafter, referred to as “LOW period”) is counted by the timer 66 as the second half of the detection period T.
[0056]
In the rotation speed detection unit 62 according to the present embodiment, as shown in FIG. 5B, each of the timers 64 and 66 counts up to the maximum count value when rotating at the lowest speed in the rotation speed detection target range. The counting period is set as follows.
[0057]
In this embodiment, as shown in FIG. 7, it is assumed that the detection period T (in FIG. 7, '1 cycle') is counted by a single timer without being divided, and the minimum speed When the timer is set to count up to the maximum count value during rotation at, the count cycle is 1 ms, and 0.5 ms, which is 1/2 of the count cycle, is the count cycle of each of the timers 64 and 66. It has been.
[0058]
On the other hand, the memory 70 is for storing the count values of the timer 64 and the timer 66, and the count processing unit 68 converts the count values of the timer 64 and the timer 66 stored in the memory 70 to the latest count values, respectively. Update sequentially.
[0059]
In addition, the arithmetic processing unit 72 executes a rotation speed calculation process of calculating the rotation speed of the shaft 20 for each detection cycle T using the count values of the timer 64 and the timer 66 stored in the memory 70. ing.
[0060]
Hereinafter, the operation of the present embodiment will be described. When driving of a driving member (not shown) is instructed by an operation signal from the operation unit 58, the CPU 50 starts control for rotating the shaft 20 of the brushless motor 12 at a predetermined rotation speed. As a result, the rotation drive of the shaft 20 is started, and the output of the Hall IC signals Hu to Hw from the Hall IC elements 44U to 44W to the rotation speed detection unit 62 is started.
[0061]
When the Hall IC signals Hu to Hw are input to the rotation speed detection unit 62, the count processing unit 68 performs a count process.
[0062]
FIG. 4 is a flowchart showing the flow of processing of the count processing program executed by the count processing section 68 at this time. The count processing of the present embodiment will be described with reference to FIG. In the following, for convenience, the timer 64 is referred to as an H timer 64, and the timer 66 is referred to as an L timer 66.
[0063]
First, in step 102, the process waits until the Hall IC signal Hu changes to the “HIGH” level. In the next step 104, the count value of the timer 64 for H is reset in order to measure the HIGH period of the Hall IC signal Hu. The counting is started, and thereafter, the process proceeds to step 106 and waits until the Hall IC signal Hu switches to the “LOW” level.
[0064]
Thereafter, the process proceeds to step 108, where the count value tH of the H timer 64 is stored in the memory 70, and then proceeds to step 110, where the count value of the L timer 66 is reset to measure the LOW period of the Hall IC signal Hu. And start counting.
[0065]
In the next step 112, the process waits until the Hall IC signal Hu changes to the "HIGH" level. In the next step 114, the count value tL of the L timer 66 is stored in the memory 70, and thereafter, the process returns to the step 104. .
[0066]
Thereafter, the processing of steps 104 to 114 is repeated, and while the Hall IC signal Hu is being input, the detection cycle T of the Hall IC signal Hu is counted by this processing, and the count value of the memory 70 is updated.
[0067]
On the other hand, when the Hall IC signals Hu to Hw are input to the rotation speed detection unit 62 and storage of the count values tH and tL in the memory 70 is started, the rotation processing unit 72 executes the rotation speed calculation process. Is done. FIG. 6 is a flowchart showing the flow of the processing of the rotation speed calculation processing program executed by the calculation processing section 72 at this time. The rotation speed calculation processing according to the present embodiment will be described with reference to FIG.
[0068]
First, in step 118, the process waits until the Hall IC signal Hu changes to the "HIGH" level. In the next step 120, the count value tH and the count value tL stored in the memory 70 at this time are summed up. The count value x of the entire detection cycle T is calculated, and then the process proceeds to step 122.
[0069]
Incidentally, the detection cycle T of the Hall IC signal Hu of the brushless motor 12 according to the present embodiment corresponds to 30 degrees rotation of the sensor magnet 76, that is, 1/12 rotation. Since the counting cycle of the timers 64 and 66 is 0.5 ms, the period R (s) per rotation of the sensor magnet 76 can be expressed by the following equation (2).
[0070]
(Equation 2)
[0071]
Further, the number of rotations K1 (rps) per second is represented by the reciprocal of the period R as shown in the equation (3).
[0072]
[Equation 3]
[0073]
Therefore, since the rotation speed K (rpm) is the number of rotations per minute, it can be expressed by the following equation (4).
[0074]
(Equation 4)
[0075]
Therefore, the arithmetic processing unit 72 according to the present embodiment basically calculates the rotation speed K using Expression (4).
[0076]
However, in the arithmetic processing unit 72 according to the present embodiment, when performing division, 2 bytes are assigned to the numerator and 1 byte is assigned to the denominator. Therefore, when calculating the rotation speed K by the equation (4), the count value x as the denominator needs to be a value (0 to 255) within a range that can be represented by 1 byte.
[0077]
Therefore, in the rotation speed calculation processing according to the present embodiment, it is determined whether or not the count value x is less than 256 in step 122, and if the determination is affirmative, the process proceeds to step 124 to directly apply the above equation (4). Is used to calculate the rotation speed K, and thereafter, the process returns to step 118.
[0078]
On the other hand, if a negative determination is made in step 122, it is considered that the count value x overflows, and the flow shifts to step 126, where the value of the numerator of equation (4) (= 10000) is obtained by dividing the count value x by half. ) Is divided by half (= 5000) to calculate the rotation speed K, and thereafter, the process returns to step 118.
[0079]
Table 2 shows an example of a calculation result of the rotation speed obtained by the above-described rotation speed calculation processing. Here, in order to make it possible to compare with the prior art shown in Table 1, the case where the detection cycle T is the same as that shown in Table 1 at both low speed rotation and high speed rotation is shown. I have.
[0080]
[Table 2]
[0081]
As shown in Table 2, at the time of high-speed rotation, the difference between the rotation speeds per timer 1 count was 26 rpm, and the difference between the rotation speed per timer 1 count at the time of high-speed rotation shown in Table 1 (56 rpm) and It can be seen that the comparison is about half.
[0082]
That is, the rotation speed detection unit 62 according to the present embodiment divides one cycle of the Hall IC signal Hu, which has been conventionally counted without being divided, into two, and reduces the period of each divided region to half of the conventional one. After counting in the counting cycle, the count value of each divided area is summed to derive a one-cycle count value, whereby the count range of the count processing unit 68 is doubled to limit the count range. , The deterioration of the rotational speed resolution caused by the rotation speed is suppressed, and the detection accuracy of the rotational speed is made twice as high as that of the related art regardless of the rotational speed.
[0083]
In addition, the rotation speed detection unit 62 according to the present embodiment does not need to switch the calculation method of the rotation speed according to the rotation speed, and thus can be easily realized as compared with the conventional technology for performing the switching.
[0084]
As described above in detail, the rotation speed detection unit 62 according to the present embodiment counts one cycle of the Hall IC signal Hu which is a pulse signal generated according to the rotation angle of the shaft 20 of the brushless motor 12. In detecting the rotation speed based on the one-cycle count value obtained by the above, one cycle of the Hall IC signal Hu is divided into two, and the period of each divided region is counted without dividing one cycle. Assuming that one-half of the counting period as a counting period is counted as the counting period, and the above-mentioned one-period count value is derived by summing up the counted values of the respective divided areas, regardless of the rotation speed, The rotation speed can be easily and accurately detected.
[0085]
In addition, since the rotation speed detection unit 62 according to the present embodiment uses the Hall IC signal Hu from the Hall IC element 44U, the rotation speed can be easily and accurately determined regardless of the rotation speed in the device. Can be detected.
[0086]
In addition, the rotation speed detection unit 62 according to the present embodiment starts counting the second divided area in synchronization with the switching of the signal level within one cycle of the Hall IC signal Hu. A period can be counted for each divided area.
[0087]
In the rotation speed detection unit 62 according to the present embodiment, the calculation processing unit 72 derives the rotation speed of the motor by an operation involving division by a one-cycle count value as shown in Expression (4), and obtains the rotation speed of the motor. In some cases, if the one-cycle count value exceeds a predetermined upper limit value (255) and overflows, the one-cycle count value and the value to be divided are assumed to be divided by a predetermined value, and the rotation speed of the motor is calculated. Therefore, the occurrence of an overflow of the one-cycle count value can be avoided beforehand, and the calculation result of the rotational speed can be prevented from being undefined when the overflow occurs.
[0088]
In the present embodiment, a case has been described in which the rotation speed is calculated based only on the Hall IC signal Hu. However, the present invention is not limited to this, and a count process is performed on each of the Hall IC signals Hu to Hw. A rotation speed calculation process may be performed using the count values obtained by the respective count processes, and the rotation speed may be detected by obtaining an average value of the obtained three rotation speeds.
[0089]
Also, a count process may be performed on each of the Hall IC signals Hu to Hw, and a rotational speed calculation process may be performed using the average value of each count value obtained by each count process to detect the rotational speed. Good.
[0090]
Further, in the present embodiment, the case where the count processing (see FIG. 4) and the rotational speed calculation processing (see FIG. 6) are executed by software processing has been described, but the present invention is not limited to this. Each processing may be executed by hardware processing. In this case, a higher rotation speed can be detected as compared with the present embodiment.
[0091]
Further, in the present embodiment, a mode in which one cycle of the Hall IC signal is divided into two to measure time has been described. However, the present invention is not limited to this, and one cycle of the Hall IC signal can be divided into three, four, etc. Can be finely divided. In this case, for example, the frequency of the Hall IC signal is appropriately converted using a frequency multiplier, and the division position is determined based on the period of the converted signal, whereby one period can be divided into a plurality of periods.
[0092]
In the present embodiment, the Hall IC elements 44U to 44W have been described as detecting the change in the magnetic field at each of the positions where the sensor ICs 76 are integrally fixed to one end of the shaft 20. The IC elements 44U to 44W may be configured to detect a change in the magnetic field by the magnet 24 provided on the inner peripheral portion of the rotor 22, and in this case, the sensor magnet 76 does not need to be separately provided.
[0093]
Furthermore, the flow of each process of the count process and the rotational speed calculation process, the configuration of each unit, and various set values shown in the present embodiment are examples, and it is possible to appropriately change each of them without departing from the gist of the present invention. Needless to say.
[Brief description of the drawings]
FIG. 1 is a partially cutaway side view of a brushless motor according to an embodiment.
FIG. 2 is a block diagram of a portion related to driving of a brushless motor 12 according to the embodiment.
FIG. 3 is a block diagram of a portion related to a rotation speed detecting function in a motor control unit 10 of the brushless motor according to the embodiment.
FIG. 4 is a flowchart illustrating a flow of processing of a count processing program executed by a count processing unit in the embodiment.
FIG. 5 is a waveform chart showing a relationship between a Hall IC signal and an output signal of a timer according to the embodiment.
FIG. 6 is a flowchart illustrating a flow of processing of a rotation speed calculation processing program executed by a calculation processing unit in the embodiment.
FIG. 7 is a waveform diagram showing a relationship between a Hall IC signal and an output signal of a timer according to a conventional technique.
[Explanation of symbols]
Reference Signs List 20: shaft (rotating axis), 44U, 44V, 44W: Hall IC element (detecting means), 62: rotational speed detecting section, 64, 66: timer (counting means), 68: count processing section (counting means), 70 ... Memory, 72 ... Calculation processing unit (calculation means, derivation means), 76: Sensor magnet (magnetic material)

Claims (5)

  1. A motor rotation speed detection device for detecting a rotation speed based on a one-cycle count value obtained by counting one cycle of a detection signal which is a pulse signal generated according to a rotation angle of a rotation shaft of the motor. hand,
    One cycle of the detection signal is divided into N (N is an integer of 2 or more), and 1 / N of the counting cycle is counted assuming that the period of each divided area is counted without dividing one cycle. Counting means for counting as a cycle,
    Deriving means for deriving the one-cycle count value by summing the count values of the respective divided areas counted by the counting means;
    A rotation speed detection device for a motor, comprising:
  2. The detection signal is a signal obtained by detecting a change in a magnetic field generated by a magnetic body provided such that the polarity is alternately changed at substantially equal intervals in the rotation direction on the rotation shaft by rotation of the rotation shaft. 2. The motor rotation speed detecting device according to claim 1, wherein:
  3. The N is 2,
    3. The rotation speed of the motor according to claim 1, wherein the counting unit starts counting of the second divided area in synchronization with a signal level switching timing within one cycle of the detection signal. Detection device.
  4. By dividing a predetermined divided value by the one-cycle count value based on a predetermined rotation angle of the rotary shaft corresponding to one cycle of the detection signal and a counting cycle by the counting means, the rotation speed of the motor is obtained. When the one-cycle count value exceeds a predetermined upper limit and overflows, the one-cycle count value and the division value are divided by a predetermined value to calculate the rotation speed of the motor. 4. The motor rotation speed detection device according to claim 1, further comprising a calculation unit that performs the calculation.
  5. A motor rotation speed detection method for detecting a rotation speed based on a one-cycle count value obtained by counting one cycle of a detection signal which is a pulse signal generated according to a rotation angle of a rotation shaft of the motor. hand,
    One cycle of the detection signal is divided into N (N is an integer of 2 or more), and 1 / N of the counting cycle is counted assuming that the period of each divided area is counted without dividing one cycle. Count as a cycle,
    Deriving the one-period count value by summing the counted values of the divided regions,
    Motor rotation speed detection method.
JP2002324929A 2002-11-08 2002-11-08 Method and apparatus for detecting rotation speed of motor Pending JP2004157066A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002324929A JP2004157066A (en) 2002-11-08 2002-11-08 Method and apparatus for detecting rotation speed of motor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002324929A JP2004157066A (en) 2002-11-08 2002-11-08 Method and apparatus for detecting rotation speed of motor

Publications (1)

Publication Number Publication Date
JP2004157066A true JP2004157066A (en) 2004-06-03

Family

ID=32804323

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002324929A Pending JP2004157066A (en) 2002-11-08 2002-11-08 Method and apparatus for detecting rotation speed of motor

Country Status (1)

Country Link
JP (1) JP2004157066A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1330964C (en) * 2006-05-23 2007-08-08 北京航空航天大学 Apparatus for detecting rotation speed and direction of rotor of magnetic levitation reacted flywheel
KR100911722B1 (en) 2007-11-30 2009-08-10 한국전기연구원 Apparatus For Measuring Velocity And Angle Of Rotator Using Hole Device
JP2012163412A (en) * 2011-02-04 2012-08-30 Nsk Ltd Physical quantity measurement instrument for rotating member

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1330964C (en) * 2006-05-23 2007-08-08 北京航空航天大学 Apparatus for detecting rotation speed and direction of rotor of magnetic levitation reacted flywheel
KR100911722B1 (en) 2007-11-30 2009-08-10 한국전기연구원 Apparatus For Measuring Velocity And Angle Of Rotator Using Hole Device
JP2012163412A (en) * 2011-02-04 2012-08-30 Nsk Ltd Physical quantity measurement instrument for rotating member

Similar Documents

Publication Publication Date Title
US8575874B2 (en) Electronically commutated motor with correction of sensed rotation-direction signal
EP0316077B1 (en) Brushless motors
KR940006961B1 (en) Commutation circuit for dc motor
JP5175569B2 (en) Synchronous motor drive system
JP4513536B2 (en) Inverter device
EP0462729B1 (en) Method and apparatus for detecting the rotor position of a brushless DC motor
JP3726683B2 (en) Method and apparatus for controlling position sensorless motor
US6940235B2 (en) Method and apparatus for driving a brushless DC motor
JP5824660B2 (en) Phase shift detection device, motor drive device, brushless motor, and phase shift detection method
US6081091A (en) Motor controller, integrated circuit, and method of controlling a motor
US6791293B2 (en) Sensorless control device for synchronous electric motor
JP3397007B2 (en) Brushless motor
US6956340B2 (en) Method for processing data for an electronically commutated motor and motor for carrying out said method
JP4100442B2 (en) Motor drive control device and motor drive control system
US8339076B2 (en) Electric motor drive control apparatus
JP4483009B2 (en) Motor control device
KR101066749B1 (en) Brushless motor device and control method thereof
EP0382166A1 (en) Speed control apparatus for movable equipment
JP5413424B2 (en) Motor drive device and brushless motor
DE10054594B4 (en) Device for detecting the rotor position in a brushless dc motor
US8258731B2 (en) Apparatus and method for starting motor
EP0744807A1 (en) DC motor current limiting method and DC motor for implementing this method
US6538404B2 (en) Motor apparatus
EP1246355A2 (en) Apparatus for driving sensorless motor
JP2010273502A (en) Motor drive apparatus and motor drive method

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20050419

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20070312

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20070424

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20070625

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20070724

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20070925

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20071023