JPH0574319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor control device used in office automation (OA) equipment such as printers for personal computers and word processors.

[Prior Art] An encoder having an integer multiple of the number of magnetic poles of a rotor, and a counting means for counting the number of detected parts of the encoder as the rotor rotates at a predetermined location on the stator side. When a step motor (also referred to as a stepping motor) is driven in a DC motor mode (hereinafter referred to as a DC motor drive) in a motor control device that switches the energization to the stator coil when the count value of the stator matches a predetermined value, ) and stepping motor mode (hereinafter referred to as stepping motor drive), conventionally, a special excitation pattern generating means for driving the stepping motor is provided, and the signals for both modes are provided. This was achieved by switching by a signal switching means.

[Problems to be Solved by the Invention] However, when driving in this manner, there are the following problems.

(1) Smooth switching is not possible. In other words, since the position of the rotor was not grasped, the excitation pattern became discontinuous when switching the drive method.
Motor malfunctions.

(2) An excitation pattern generator is required to drive the stepping motor.

An object of the present invention is to enable smooth switching between DC motor drive and stepping motor drive without any erroneous steps.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a motor driving means for controlling the current supplied to the coil of the step motor, and a motor driving means for detecting the rotational movement of the rotor of the step motor and detecting the rotational movement of the rotor of the step motor. A detection means that generates a pulse signal according to the rotational operation of the rotor, and a DC motor that counts the pulse signal from the detection means and generates a first drive control signal for driving the DC motor according to the count value. a control means having a drive signal generating means and a pattern matching means for pattern matching the first drive control signal, and generating a second drive control signal for driving the step motor that is matched by the pattern matching means; It is characterized by comprising a signal switching means for applying either a first drive control signal or a second drive control signal to the motor drive means in response to a switching signal from the control means.

[Function] According to the present invention, the first drive control signal, which is an output signal for counting pulse signals generated according to the rotational operation of the rotor and driving the DC motor according to the counted value; By switching between the signal and the second drive control signal which is an output signal for driving the stepping motor by matching the pattern, it is possible to smoothly switch between DC motor drive and stepping motor drive. I can do it.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIGS. 1 to 15 show a first embodiment of the present invention. First, FIG. 1 is a drive control circuit diagram of a motor according to the present embodiment, and FIGS. 2 and 3 are a perspective view and a sectional view, respectively, showing a configuration example of the motor according to the first embodiment of the present invention. be.

In FIGS. 2 and 3, reference numeral 201 is a motor capable of stepwise rotation and has a built-in magnetic encoder. This motor 201 has a stator 204 having a structure in which two stators 202 and 203 having magnetic hollow rings are stacked one above the other.
The surfaces of the stators 202 and 203 are made of magnetic material, and the inner periphery has magnetic pole pieces for forming N and S magnetic poles alternately in the circumferential direction.
5,206, stator 202 has 207,
208) are formed alternately at minute intervals, and a bobbin 210 on which a conductive wire 209 is wound in many turns is inserted into a hollow portion inside the bobbin 210.

The magnetic pole pieces 205, 206, 207, and 208 are arranged and fixed in two stages, upper and lower, so as to face each other in the axial direction. Magnetic pole pieces 205, 206, 2
The widths of 07 and 208 are equal to the circumferential magnetic pole width of the magnet rotor 211. Pole pieces 205 and 207 are connected to stators 202 and 2
They are each formed by extending the magnetic material portion on the lower surface of 03 upward toward the inner periphery, and are also formed to be shifted from each other by a quarter pitch. Further, the magnetic pole pieces 206 and 208 are each formed by extending the magnetic portions of the upper surfaces of the stators 202 and 203 toward the inner circumference downward, and are also formed to be shifted from each other by a quarter pitch. 212 and 213 are lead wires connected to the conductive wires of the stators 202 and 203, respectively.

The cylindrical magnet rotor 211 is connected to the rotating shaft 2.
14 so that they can rotate together.
This magnet rotor 211 has a stator 20
Flanges 215, 216 welded to 2,203
The stator 204 is supported by bearings 217 and 218 mounted on the stator 204, respectively, so that the stator 204 is rotatably disposed within the inner hollow portion of the stator 204. The magnet rotor 211 may be a plastic magnet or a sintered magnet, and any suitable magnet may be used. This magnet rotor 211
N and S magnetic poles are alternately radially aligned and magnetized on the outer periphery of the magnetic pole so as to face the magnetic pole pieces 205, 206, 207, and 208.

The rotating shaft 214 is arranged to protrude from the lower end of a bearing 218 attached to a flange 216 welded to the stator 202, and N and S are provided at minute intervals around the entire circumference of the protruding portion of the rotating shaft 214. Magnetic encoder 21 with 288 magnetic poles alternately magnetized
I am wearing 9. At a location facing the magnetic pole part 224 (periphery part) of this magnetic encoder 219, A
Magnetic sensor (MR element) 2 configured so that phase and B phase signals are output with a 90° shift in electrical phase.
20 are arranged.

This magnetic sensor (MR element) 220 is attached to a fixed member 222, and an output signal is sent to the first
The signal is sent to the illustrated control circuit. 225 is stator 2
This is a metal cup-shaped magnetic encoder storage case fixed to 02, and a fixing member 222 to which a magnetic sensor (MR element) 220 is fixed is attached to the bottom of the inner surface. Note that this prevents dirt and dust from adhering to the surface of the magnetic pole part 224 and magnetic sensor (MR element) 220 inside this storage case 225.

In this embodiment, the number of magnetic poles of the magnet rotor 211 is 24, and the number of magnetic poles of the magnetic encoder 219 is 288, which is an integral multiple thereof. Therefore rotor pole 1
The number of encoder output pulses per pole is 12.

In the present embodiment, the rotation angle per pulse of the encoder output is 1.25 degrees/pulse (360 degrees/288 pulses), which is a value that is + minutes smaller than the rotation angle of 15 degrees of one rotor pole. That is, even without any adjustment, the maximum error in the position between the encoder output pulse and the rotor magnetic pole is ±0.625 degrees, which is an error of about 4.2% for one rotor pole, which is a value that can be completely ignored. The relationship between the number of encoder output pulses and the number of rotor magnetic poles may be set within a permissible error range, and the number of encoder output pulses per rotation of the rotor may be an integral multiple of the number of rotor magnetic poles. In general, an error of ±12.5% is sufficient;
In that case, the number of pulses will be four times the number of rotor magnetic poles.

In addition, when the number of rotor magnetic poles is 100, such as in a hybrid step motor, and when the number of encoder output pulses and the number of rotor magnetic poles correspond one-to-one, as with conventional Hall elements or other encoders, , precise adjustment is required to align both. However, according to this embodiment, by setting the number of encoder output pulses to 400 to 500, it is possible to make a motor with a hybrid step motor structure function like a DC brushless motor without the above alignment. . This level of output pulse is a magnetized pattern with a wavelength of 0.334 μm, and a magnetic encoder with a diameter of 26.6 mm (structured as shown in Figures 2 and 3) and a magnetoresistive element (MR element).
This can be easily realized by

FIG. 1 shows an example of the configuration of a motor control circuit configured as described above. In FIG. 1, 220A,
220B is a magnetoresistive element (MR element) shown by 220 in FIGS. 2 and 3, 103 and 104 are differential amplifiers, 105 and 106 are comparators,
107 is an up-down clock generator that generates the UP clock and DOWN clock according to this embodiment;
108 is an up-down counter, 109 is a motor drive signal generator, 110 is a motor drive circuit, 111 is a position detection counter, 11
2 is an external control device, 113 is a speed control reference signal generator, and 114 is a motor speed control device.

The operation of the drive circuit will be explained with reference to this figure.

The MR element 220A, as shown in FIG. 4A,
Four magnetoresistive elements r1 to r4 are arranged along the magnetic pole arrangement direction of the magnetic pole part 224. In the figure, the MR element 220A is shown by a solid line, and the MR element 220B is shown by a dotted line.

Elements r1 to r4 are connected in a bridge configuration as shown in FIG. 4B, and generate an output voltage in response to changes in the external magnetic field. Although FIG. 4B only shows the MR element 220A, the MR element 22
The same applies to 0B.

The four elements constituting the other MR element 220B are the MR element 22, as shown by dotted lines in FIG. 4A.
It is placed in the middle of the four 0A elements r1 to r4.

In this example, since the MR element is placed facing the magnetic encoder attached to the motor shaft, the waveform shown in Fig. 5 is obtained in response to the magnetic field fluctuation caused by the magnetic encoder as the motor rotates. . Two MR elements are arranged with a phase shift of 1/8 period with respect to the magnetization period of the magnetic encoder, so if one MR element 220A has a waveform indicated by reference numeral 501 in FIG. The element 220B, as indicated by reference numeral 502 in FIG.
A waveform whose phase is electrically shifted by 90° is obtained.

These waveforms are transmitted to the next stage differential amplifier 103,1.
04, the comparator 10
5,106, the code 503 (waveform 5) in FIG.
01) and 504 (corresponding to waveform 502), and then input to the UP-DOWN clock generator 107.

This clock generator 107 consists of two D-type flip-flops 601 and 60, as shown in FIG.
2, it has two input terminals 603, 604 for inputting input signals A, B, and two output terminals 605, 606 for UP and DOWN. ) generates an UP clock or a DOWN clock.

FIG. 7 shows waveforms 603 and 604 of signals A and B,
6 is a diagram showing the relationship with UP-DOWN output waveforms 605 and 606. FIG. Note that the two arrows in the figure indicate the flow of time in the UP direction or DOWN direction.

Now, in FIG. 7, if signals A and B in the UP direction are input to the clock generator 107, the two waveforms shown at 701 and 702 in FIG.
Appears on the DOWN output terminal. That is, pulses corresponding to the surroundings of the magnetic encoder appear only at the UP terminal, and nothing is output at the DOWN terminal. Conversely, when pulse signals A and B viewed from the DOWN direction in FIG. 7 are input, the signals 703 and 7
The waveform shown in 04 is output to the UP and DOWN terminals. In other words, there are two MRs depending on the rotor rotation direction.
Since the phase relationship of the signals output from the elements is determined by one of the two arrows in FIG. 7, the UP-DOWN clock generator 107 outputs an output corresponding to the direction of rotation.

Next, the UP-DOWN clock signal is connected to the two UP-DOWN clock signals.
- input to DOWN counters 108 and 111; The UP-DOWN counter 108 is a 5-bit radix 24 counter, which counts up or down according to the input UP clock signal 121 or DOWN clock signal 122, and counts up or down in decimal notation, corresponding to numbers from "0" to "23". is a 5-bit signal in binary representation (each signal is B0, B1, B2, B
3, B4) is output to the output terminal. The output of the counter 108 is the motor drive signal generator 10
9 is input.

The motor drive signal generator 109 includes four digital comparators 801 and 8 as shown in FIG.
02,803,804, clock generator 805,
It consists of a signal switch 850, a rotation direction switch 806, and a start/stop controller 807. Start stop controller 807 is configured as shown in FIG. 9, for example, and includes OR circuits 1101 to 1104 that receive a start stop (S/S) signal from external control device 112 and signals 816 to 819, respectively. ing.

Digital comparators 801-804 generate clock signals when the same data as a preset value is input. Therefore, each of the four digital comparators has a value from “0” to “23” in decimal notation.
By setting any of the values up to 5 bits in binary, a pulse signal can be output when the UP-DOWN counter 108 indicates a predetermined value. Output signal 8 of four digital comparators
08, 809, 810, and 811 are input to clock generator 805.

10 and 11 show the clock generator 8.
As shown in these figures, the clock generator 805 is composed of two or four R-S flip-flops.

Now, let us assume that the clock generator 805 is shown in FIG.
00110B), c=12(=01100B), d=18(=
10010B).

The operation of clock generator 805 will be described with reference to FIG. 12A. Signal 1301 in the diagram is UP
-DOWN Indicates the input clock signal waveform (UP or DOWN) to counter 108, and the number above the waveform indicates the count value (decimal) of the counter.
The count value of the above settings (decimal) “0”, “6”,
Digital comparator 80 when “12” and “18”
Pulse output signals 808 to 811 outputted from the clock generators 1, 802, 803, and 804 are input to corresponding terminals a to d of the clock generator shown in FIG. At this time, the signal 8 from the four output terminals of the two R-S flip-flops 901 and 902
As 12, 813, 814, 815, clock signals such as 1302, 1303, 1304, 1305 in FIG. 12A are output. That is, these outputs are uniquely determined by the count value (decimal) from "0" to "23".

This signal 1302, 1303, 1304, 13
05 represents the energization signal to the two-phase coils 2021 and 2031, and is represented by A, B, ., respectively. These A, B,, signals are transferred to the motor drive circuit 1.
10 and energizes the coils 2021 and 2031.

The A-phase coil 2031 is activated when the input clock to the UP-DOWN counter 108 is “0” or “12”, and the B-phase coil 2021 is activated when the input clock to the UP-DOWN counter 108 is “6” or “ The current direction is switched when it is 18”.

Focusing on one phase, the energization direction changes every 12 pulses, in other words, the energization changes every 180 degrees in electrical angle.

The timing of energization switching is based on the magnetic poles of the rotor and the output value of the UP-DOWN counter 108 with reference to the position of the stator magnetic poles, and the mode of speed control is as follows.

That is, the rotor rotational speed signal 120 obtained based on the output signal from one of the magnetoresistive elements 220B is compared with the signal 133 from the speed control reference signal generator 113, and the rotor is adjusted so as to eliminate the difference between the two. Control speed. When the rotor speed becomes slower than the set value (the value indicated by the speed control reference signal 133), the signal 1 from the comparator circuit 114
34, the phase compensation circuit 155 and the voltage control circuit 1
Coil 2 in motor drive circuit 110 via 16
The applied voltage to 021 and 2031 is increased to speed up the rotation of the rotor, and conversely, when the speed becomes faster than the set value, the applied voltage is lowered to keep the rotor speed constant.

By the way, the comparison value of the digital comparator is based on the control signal 130 from the external control device 112.
It can be set arbitrarily by

That is, in this embodiment, the encoder pulses are subdivided into 12 pulses per magnetic pole of the rotor, so that the energization timing can be changed from the normal energization timing.

FIG. 12B shows a case where the energization timing is accelerated, and the phase is advanced compared to the normal energization timing (FIG. 12A).

FIG. 12C shows a case where the energization timing is delayed, and the phase is delayed from the normal energization timing (FIG. 12A).

By advancing or delaying the phase in this manner, optimal control can be performed when the speed is unstable due to rotor acceleration/deceleration, load fluctuations, etc.

For example, the set value of the digital comparator 801 is a=23, the set value of the digital comparator 802 is set to b=5, the set value of the same 803 is set to c=11, and the same is set to d=17.
5, the numbers 1307 to 1 in Figure 12B
The clock generator 80 receives a waveform signal whose phase is advanced by one pulse of the input clock as shown at 310.
5 as output signals 812 to 815. Similarly, the comparison values of the comparator are a=1, b=7, c
=13, d=19, symbol 131 in Figure 12C
Output signals 812 to 815 having waveforms whose phases are delayed by one pulse indicated by 2 to 1315 are obtained. That is, four output signals 812 to 815 of phases corresponding to the count value of the UP-DOWN counter are outputted to the clock generator 80 by an external signal 130.
5.

Furthermore, if the clock generator 805 shown in FIG. 11 is used, the energization timings shown in FIGS. 13A to 13C can be obtained. In Figure 13A,
1401 is the encoder output waveform, 1402, 14
03, 1404, 1405 are two-phase carp 202
1,2031 represents the energized state, A, respectively.
B, , represents four signals. In this case, A
For the phase, the output of the UP-DOWN counter 108 is “0”,
When “6”, “12”, “18”, B phase is UP-
The output of the DOWN counter 108 is “0”, “6”,
The energization and energization direction are switched when "12" and "18" are selected.

In this case, the energization is switched every 90 degrees in electrical angle. This energization method is similar to the one-phase excitation method of bipolar drive.

The energization method for every 180° as already explained (Fig. 12)
Compared to this, the current flowing through the coil is halved because the energization time is shortened, but the rotational torque obtained is approximately 1/√2. This is similar to the comparison between two-phase excitation and one-phase excitation of a normal motor, and can be used depending on driving conditions and the like. Even in the case of energization every 90°, the phase of the energization timing described above can be changed in the same way (see FIGS. 13B and 13C).

According to the above configuration, the rotor position is monitored based on the combination of the encoder and the MR element, and when the status magnetic pole and the rotor magnetic pole match, the excitation pattern is switched, so the original characteristics of a step motor are lost, and the DC Although motor characteristics are realized, according to this example, operation as a step motor is also realized with the same control circuit.

That is, signal switch 850 switches signals 812, 813, 814, 81 from clock generator 805.
5 and signals 824, 8 from the external control device 112.
25, 826, and 827 using a switching signal 828 from an external control device to switch between DC motor drive and stepping motor drive.

The DC motor drive is as explained above, but the stepping motor drive uses signals 824 and 824.
25,826,827. That is, the external control device 112 internally holds the one-phase excitation pattern shown in FIG. 13A and the two-phase excitation pattern shown in FIG. 12A, and outputs these patterns to signal lines 824, 825, 826, and 827 as appropriate. Then, the motor 201 is operated as a stepping motor. Since the stepping motor rotates by a predetermined step angle each time the excitation pattern is switched, the external control device 112 can control the speed of the motor 201 according to the output timing of the pattern.

By the way, DC motors can rotate at high speeds without vibration when starting and stopping, while stepping motors can be easily positioned, but they have different operating characteristics such as large vibrations at low speeds, so it is necessary to use them properly for optimal operation. be. Therefore, in order to smoothly switch between the two driving methods, the external control device 112 transmits rotor position information to signals 812, 813, 81 output from a clock generator, as shown in FIG.
We know this by monitoring 4,815. In normal DC motor driving, the motor 201 is driven by these signals 812, 813, 814, and 815. Therefore, when switching from DC motor drive to stepping motor drive, motor 20
Whether the motor 1 is stationary or rotating, the clock generator 8 outputs the initial excitation pattern of the step operation.
05 can be switched without making a mistake by matching the pattern outputted immediately before that.

This also serves as an example of the initial setting of the motor counter. In other words, the initial setting of the counter is 2.
This is done by exciting one phase of the phase motor, but this can be easily achieved by setting the motor drive to stepping mode and selecting a one-phase excitation pattern.

Next, the clock generator output signals 812-81
5 is input to a rotation direction switch 806 as shown in FIG. The rotation direction switch 806 is composed of four multiplexers, and the external control device 11
The input signals are distributed and output according to the motor rotation direction instruction signal 129 from 2. Also, for example, the OR circuit 1101 provided in the start/stop controller 807 may be
The motor can be stopped by setting all of the output signals 124 to 127 of the motors 1104 to 1104 to a "High" state.

In FIG. 1, 110 indicates two stators 20.
Coil 2 consisting of conducting wire 209 provided in 2, 203
021 and 2031, and in this example, it is a bipolar drive circuit. This motor drive circuit 110 receives output signals 124 to 126 from the motor drive signal generator 109.
Rotate the motor forward or backward based on the

Note that the rotor position can be determined by counting the signal from the magnetic sensor (MR element) 220 using the UP-DOWN counters 108 and 111. The initial state is the position where the magnetic poles of the rotor and the magnetic poles of the stator are facing each other, and the UP-
The outputs of DOWN counters 108 and 111 are set to "0". From now on, even if the motor is stopped, this setting remains valid as long as the rotation power is not turned off.

Specifically, two-phase coils 2021 and 20
31, one phase is energized in a fixed direction. At this time, the magnetic poles of the stator phase on the energized side and the magnetic poles of the rotor magnet are facing each other, and at this point the UP
- Give reset signals 131 and 132 from external control device 112 so that the outputs of DOWN counters 108 and 111 become "0". Through this operation, it is possible to obtain a position information signal in which the rotor position is subdivided into 1/12 based on the point where the rotor magnetic poles and the stator magnetic poles face each other.
The position of the rotor can be known based on the output values of the DOWN counters 108 and 111, and it becomes possible to switch the energization to the coils.

In addition, as shown in FIG. 14, four coils 1
201, 1202, 1203, 1204 are used, and the motor drive signal generator 1 shown in FIG.
Four drive signals 124, 125, 12 from 09
By applying 6,127, the motor shown in FIGS. 2 and 3 can be driven unipolarly. The drive signal energization method used is the same as the bipolar drive (FIG. 1). This can also be used depending on driving conditions and the like.

As explained above, compared to the number of magnetic poles of the rotor,
By detecting the rotor position using encoder signals divided into 1/12 per pole, rotor speed control is stabilized and optimum control can be performed. Moreover, since encoder signals are counted, the timing of energization can be switched accurately.
Furthermore, the rotational position of the rotor can be detected and the position can be controlled.

(Second Embodiment) FIG. 15 is a diagram showing another embodiment of the present invention. In this embodiment, the signal switch 850 is provided between the motor drive signal generator 109 and the motor drive circuit 110.

This embodiment also operates in the same manner as the first embodiment, and not only can the same window effect be obtained, but also the signal switch 850 can be installed as necessary, increasing the degree of freedom in the circuit. Become.

[Effects of the Invention] As explained above, according to the present invention, it is possible to smoothly switch between DC motor drive and stepping motor drive without any erroneous steps.
It becomes possible to select the optimum driving method depending on the rotation conditions.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a motor control device according to a first embodiment of the present invention, and FIGS. 2 and 3 are a perspective view and a sectional view, respectively, showing an example of the configuration of a motor applicable to this embodiment. , Fig. 4A is a diagram showing the relationship between the MR element and the encoder in this embodiment, Fig. 4B is an equivalent circuit diagram of the MR element in this embodiment, and Fig. 5 is a waveform showing the output signal of the MR element. Fig. 6 is a circuit diagram showing an example of the configuration of the UP-DOWN clock generator of this embodiment, Fig. 7 is a timing chart showing input/output signals of the generator, and Fig. 8 is a circuit diagram showing an example of the configuration of the UP-DOWN clock generator of this embodiment. 9 is a circuit diagram showing a configuration example of a motor drive signal generator, FIG. 9 is a circuit diagram showing a configuration example of a start-stop control device, FIG. 10 is a circuit diagram showing a configuration example of a 180° clock generator, and FIG. The diagram is
Circuit diagram showing a configuration example of a 90° clock generator, Part 1
2 and 13 are timing charts showing the relationship between the UP-DOWN counter output and the energization switching signal corresponding to FIGS. 10 and 11, respectively, and FIG. 14 is a unipolar drive circuit diagram of the motor. FIG. 15 is a circuit diagram showing a second embodiment of the present invention. 220, 220A, 220B...MR element, 1
08,111...UP-DOWN counter, 109
... Motor drive signal generator, 112 ... External control device, 801, 802, 803, 804 ... Digital comparator, 212, 213, 2021,
2031...Coil, 211...Rotor, 20
2,203...Stator, 850...Signal switch.

Claims (1)

[Claims] 1. A motor drive means for controlling the current supplied to the coil of the step motor, a detection means for detecting the rotational operation of the rotor of the step motor and generating a pulse signal according to the rotational operation of the rotor, and a motor driving means for controlling the current supplied to the coil of the step motor; DC motor drive signal generation means for counting pulse signals and generating a first drive control signal for driving the DC motor according to the count value, and means for pattern matching with the first drive control signal. a control means for generating a second drive control signal for driving the step motor matched by the pattern matching means; and a control means for generating the first drive control signal and the second drive control signal according to a switching signal from the control means. A motor control device comprising: signal switching means for applying one of the signals to the motor driving means.