JPH07108118B2 - Minute angle drive circuit for stepping motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a stepping motor having a rotational movement and a stopping accuracy improved by driving the stepping motor by dividing the moving angle more minutely than before and driving the stepping motor. The present invention relates to improvement of a minute angle drive circuit.

(Prior Art) A stepping motor is also called a pulse motor or a stepping motor, and is step-driven in response to an input pulse, and various types such as two-phase to multi-phase type are put to practical use. There is. Taking a five-phase stepping motor as an example, 0.72 ° or 0.
Although it is driven at 36 °, there is a defect that the movement angle is rough and the rotation is not smooth and there is a mechanical resonance point with the drive frequency, and there is a phenomenon that it can not be driven at this frequency. There was a drawback that it would occur.
Therefore, in order to overcome the drawbacks peculiar to these stepping motors, the current is controlled in the motor coils (A), (B), etc., and the direction of the combined torque vector is gradually changed to divide 0.72 ° into 10 or 20. Divide into 1 pulse
A driving method in which step driving is performed at a movement angle of 0.072 ° or 0.036 ° has been desired. In response to this demand, conventionally, as shown in FIG. 1, one motor coil (A) (B) ...
4 output devices (Tr ₁ ) (Tr ₂ ) (Tr ₃ ) (Tr ₄ )
.. is assembled in a bridge and a + V voltage is applied to the motor coils (A) (B) ..
The drive current flowing through (B) ... is detected by the phase current detection sense resistor (R ₁ ) ... for each motor coil (A) (B). Output element (T
r) is independently switching-controlled, and a torque vector is gradually changed to say (→ 0 → E) to perform a minute angle drive. That is, in the case of a five-phase pulse motor, five motor coils (A ) (B) (C) (D) (E) drive current is controlled by each of the _five motor coil control circuits (M ₁ ) to (M ₅ ) and each output element (Tr ₁ ) to (Tr ₂₀ ). ) Is appropriately switched and controlled to control the motor coil current. >> was used. (Fig. 2) (Problems to be solved and used by the invention) However, in this method, four output elements (Tr ₁ ) (Tr ₂ ) (Tr ₃ ) (T
r ₄ ) ... is assembled in a bridge and the drive current is detected and controlled for each phase. Therefore, in the n-phase stepping motor, there are n motor coil control circuits (M) (in other words,
4n output elements (Tr) (20 for 5 phase pulse motor),
This requires n detection circuits (5 in the case of a 5-phase pulse motor)}, which complicates the entire circuit and causes an increase in cost. The + V voltage is controlled for each phase. At least n output elements (Tr) are switching-controlled (in other words, (n-1) output elements (Tr) perform switching control of the rated current, and the remaining one output element (Tr) Tr)
The switching control of the minute angle drive current is performed with. ), As a result, there is a drawback that power loss and switching noise are generated due to heat generation of the n output elements (Tr). Furthermore, since the + V voltage is switching-controlled for each phase, the motor coil (A) (B) has a drawback in that a current ripple occurs in the rated current and the minute angle drive current, resulting in a lack of stability of the stop position at the time of stop.

The present invention has been made in view of such drawbacks of the conventional example, and an object of the present invention is to gradually increase the amount of drive current flowing through the motor coil in spite of a simpler circuit configuration than the conventional example. To gradually change the direction of the composite vector that combines the drive vectors, which enables a minute angle drive. In addition, it is possible to almost eliminate power loss and switching noise due to heat generation of the output element. To provide a minute angle drive circuit for a stepping motor that can eliminate the occurrence of current ripples in the rated current and minute angle drive current flowing in the coil, improve the smoothness of rotation and enhance the stability of the stop position. is there.

(Means for Solving the Problems) Claim 1 for achieving the above object is the case of a ring connection (FIGS. 3 and 9), which is connected in a ring, and (n-1) ) → (n) → (n-
1) → (n) → ... Two or more (n) -phase motor coils (A) that rotate the rotor by a small angle by being sequentially excited, and a motor coil connected in an annular shape. (A) In the (n) motor coil control circuit (M ₁ ), which consists of a series connected body of switching elements that selectively connects each connection point to positive and negative DC current. The configured stepping motor control circuit (S) and the total current (total sum of exciting currents flowing in the motor coils (A) ... Which are connected in series to the output terminals of the stepping motor control circuit (S) and are excited ( 2io) so that the total current (2io) is controlled to be constant, a total current detection sense resistor (R ₆ ), each motor coil (A), and each motor coil control circuit (M ₁ ) …… and each are connected in series, When the number of excitation phases changes from (n-1) to (n), the amount of current flowing in the idle phase is controlled by turning on / off the motor coil control circuit (M ₁ ) ... connected to the idle phase ( ix) is gradually increased, and conversely, when the number of excitation phases changes from (n) to (n-1), the motor coil control circuit (M ₁ ) connected to one excitation phase in which the phase current gradually decreases When the amount of current (ix) that flows in the excitation phase is gradually reduced by performing on / off control, the phase current (ix) that gradually increases or decreases and the one excitation phase in which the idle phase or the phase current decreases Excitation current (i ₁ ) for exciting an adjacent excitation phase, which is the sum of the gradually increasing / decreasing phase current (ix) and the adjacent exciting current (i ₁ ) shunting or joining {(i ₁ ) + (ix)}, {( i 1) + (- i
x)} is controlled so that it gradually increases / decreases at a predetermined rate, the sum of the currents {(i ₁ ) + (ix)},
A phase current detection sense resistor (R ₁ ) for detecting {(i ₁ ) + (− ix)} and a radial connection (see FIG. 7). ), Which are connected in a radial fashion, and ... (n-1) → (n) → (n-
1)->(n)-> ... Two or more (n) -phase motor coils (A) that rotate the rotor by minute angles by being sequentially excited, and motor coils radially connected. (A) is composed of (n) motor coil control circuits (M ₁ ) consisting of a series connection body of a pair of switching elements for selectively connecting the radial ends to positive and negative DC currents. Stepping motor control circuit (S) and the total current (2io) that is the sum of the exciting currents flowing in the motor coils (A) that are connected in series with the output terminals of the stepping motor control circuit (S) and are excited. To detect the total current (2io) in order to control the motor current to be constant, the total current detection sense resistor (R ₆ ), each motor coil (A) ... and each motor coil control circuit (M ₁ ) ... Are connected in series between and, When the number of excitation phases changes from (n-1) to (n), the amount of current flowing in the idle phase is controlled by turning on / off the motor coil control circuit (M ₁ ) ... connected to the idle phase ( ix) is gradually increased, and conversely, when the number of excitation phases changes from (n) to (n-1), the motor coil control circuit (M ₁ ) connected to one of the excitation phases in which the phase current gradually decreases. When the amount of current (-ix) flowing in the excitation phase is gradually reduced by controlling the ON / OFF state, the phase current (ix) flowing while gradually increasing or decreasing, and the one excitation in which the idle phase or the phase current decreases Excitation current (i ₁ ) for exciting an excitation phase adjacent to the phase, and the sum of the gradually increasing / decreasing phase current (ix) and the adjacent excitation current (i ₁ ) shunting or joining {(i _{1) + (ix)},} {(i 1) + (- i
x)} is controlled so as to gradually increase / decrease at a predetermined rate, the sum of the current amounts {(i ₁ ) + (ix)},
It is composed of a sense resistor (R ₁ ) for phase current detection that detects {(i ₁ ) + (− ix)}.

(Operation) Then, as shown in FIG. 4 in the driving method of the first embodiment circuit, as shown in FIG. 8 in the driving method of the second embodiment circuit, Furthermore the third
In the driving method of the embodiment circuit, the motor coils (A), (B), ... Are sequentially excited as shown in FIG. 10, but a certain connection point moves as →→ ... As you go, it will be in a predetermined combination sequentially (+) →
(High impedance) → (−) or vice versa (→) → (high impedance) → (+). By gradually changing the voltage at the connection point during this time, the magnitudes of the drive vectors generated between the motor coils (A) ... And the rotors and having different directions are gradually increased or decreased, and both drive vectors are combined. By gradually changing the direction of the combined vector, the stepping motor is driven at a small angle. The voltage control at the connection point is controlled by detecting the current flowing through the phase current detection sense resistor at the connection point of each phase. On the other hand, the DV voltage (+) is controlled by detecting the current flowing through the total current detection sense resistor.

Here, the excitation patterns shown in FIG. 4 to FIG. 4 are shown as an example, and the excitation procedure is sequentially changed to another excitation pattern in the same procedure.

(Embodiment) Hereinafter, the circuit of the first embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, two types of 5-phase stepping motors of the pentagon connection type and the star connection type will be described as an example, but the present invention is not limited to this and can be applied to 2-phase to multi-phase stepping motors. Needless to say. In the figure, each phase is assumed to excite a positive vector with a current in the direction of the arrow.

FIG. 3 shows a first embodiment of the circuit of the present invention, which is a semiconductor chopper (1) for controlling the output of a DC power supply (not shown).
And a rated current detection circuit (not shown) for controlling the semiconductor chopper (1) by a pulse width modulation switching action.
And a flywheel diode (2) and a reactor (3) inserted in series on the output side of the semiconductor chopper (1)
And a smoothing capacitor (4) and a stepping motor control circuit (S). As the DC power supply (not shown), a DC power supply obtained by full-wave rectifying an AC power supply is generally used. Next, the stepping motor control circuit (S) will be described. First, two output elements (T
_{r 1) (Tr 2) ~} (Tr 9) (Tr 10) was allowed to adjacent connected in series constitute one set of the motor coil control circuit (M), equal to the number of phases of the stepping motor set (5-phase stepping For motors, 5 sets of motor coil control circuits (M ₁ ) ~
(M ₅ ) is connected in parallel to form a stepping motor control circuit (S). Furthermore, this output element (Tr ₁ ) (Tr ₂ )
Sense resistors (R ₁ ) to (R ₅ ) for phase current detection are connected in series between the connection points of ~ (Tr ₉ ) and (Tr ₁₀ ) and the connection points of motor coils (A) to (E) of the pentagon connection method. Connecting. Further, the total current detection sense resistor (R ₆ ) connected to the output side of the stepping motor control circuit (S) is composed of motor coils (A) to
This is to detect the total current that has flown in (E), and to keep this total current constant, drive voltage (DV)
Is controlled.

Further, FIG. 7 is exactly the same except that the motor coil (A) of FIG. 1 is replaced with a star connection from the pentagon connection.

Since a 5-phase stepping motor is adopted as an example in this embodiment, five motor coil control circuits (M ₁ ) to (M ₅ ) are provided for the A to E phases. Here, the wiring system in the figure is a wiring system called a Pentagon wiring, but by setting the connection points of the motor coils (A) to (E) to (+) and (-), the motor drive of the stepping motor motor is performed. Will be done. Of course, when the number of phases of the stepping motor is not 5, the motor coil control circuit (M) corresponding to the number of phases of the stepping motor is provided. The sense resistor (R ₁ ) for phase current detection inserted in the motor coil control circuit (M ₁ ) is provided for each phase for driving a small angle, and the sense resistor (R ₁ ) from the motor coil control circuit (M) This is for detecting a phase current flowing (or being pulled) into the motor coils (A) to (E), and a minute angle drive is performed by controlling this phase current. The phase current detection sense resistors (R ₁ ) to (R ₅ ) and the total current detection sense resistor (R ₆ ) described above have a low resistance value of about 1 ohm.

In the above configuration, the + V voltage of the constant current power supply is applied to the motor coil (A) to (E) of the pulse motor by applying the DV voltage (+) obtained by the pulse width modulation switching control, and the drive current is supplied to drive the motor. Is done. That is,
In this circuit, by gradually changing the 4-5 phase excitation sequence in the Pentagon connection, the direction of the combined vector that combines the vectors generated in the respective phases A to E of the rotor is gradually changed to perform minute angle driving. It is something to do.

a-1) First, a method of driving the circuit of the first embodiment will be described. The 4-5 phase excitation sequence in the Pentagon connection is the motor coil (A) in the order of Fig. 4 →→ …….
... is excited and the motor is driven at 1 step = 0.36 °.

Here, in the case of FIG. 4, the output element (Tr ₁ ) (Tr ₃ )
(Tr ₈ ) is turned on, the other output elements (Tr) are turned off, and the current of (2io) flows through the sense resistor (R ₄ ) for phase current detection. As a result, the connection points at both ends of E phase are The potential becomes (+), and the drive current flows from the (+) connection point to the (-) connection point in the phases other than the E phase, resulting in 4-phase excitation.

Subsequently, the output element (Tr ₁ ) is switching-controlled to gradually switch from ON to OFF, and finally is turned OFF, and the drive current flows from the (+) connection point to the (−) connection point, and the fourth It becomes the five-phase excitation state in the figure.

Next, the output element (Tr ₁₀ ) in the off state is gradually switched to the on state by the switching control, becomes the (-) potential, and the drive current flows from the (+) connection point. It will be in the state of 4-phase excitation in FIG.

Subsequently, the output element (Tr ₈ ) in the on state is gradually switched to the off state by the switching control, and the drive current flows from the (+) connection point toward the (−) connection point, and the drive current of 5 in FIG. It becomes the state of phase excitation.

After that, the output element (Tr) is sequentially turned on and off according to the excitation sequence, and a minute angle drive is performed.

In order to make this easier to understand, an explanation will be given using an equivalent circuit in which the motor coil (A) ... Is replaced with a resistor. Here, the DC resistance values of the motor coils (A) to (E) are each (R ₀ ).

a-2) In the equivalent circuit diagram shown in FIG. 5, the state in which the output element (Tr ₁ ) is on is shown in FIG. 4, and the state in which both the output elements (Tr ₁ ) and (Tr ₂ ) are off Is FIG. Here, the total current detection sense resistor (R ₆₎ (2i
(+ DV) voltage is controlled so that the current of o) always flows. (Drive voltage control) When the output element (Tr ₁ ) is on, the drive current does not flow because the both ends of the E phase have the same voltage. (State in FIG. 4) Then, by gradually turning off the output element (Tr ₁ ) by switching control, (ix) current flows in the E phase and the output element (Tr ₁ ) is completely turned off. Then, the state shown in FIG. 4 is obtained. At this time, the relationship between (i ₁ ), (i ₂ ) and (ix) is 2R ₀ · i ₁ = R ₀ · ix + 2R ₀ · i ₂ (1) Therefore, 2i ₁ = ix + 2i ₂ …… (2 ) Further, since 2i ₀ = i ₁ + i ₂ (3), substituting (3) into (2), i ₁ = (1/4) ix + i ₀ (4) is obtained.

Here, since ix = 0 when the output element (Tr ₁ ) is on (that is, the state of), i ₁ = i ₂ = i ₀ (5) is derived from (2) and (4). Get burned.

Similarly, by substituting (3) into (2), i ₂ = (1/4) ix + i ₀ (6) is obtained.

Conversely, when the output element (Tr ₁ ) is off (that is, the state of)
In the case of, i ₁ = 1.2i ₀ i ₂ = ix = 0.8i ₀ .

Here, (i ₀ ) can be considered as a constant because it is a current defined by the total current detection sense resistor (R ₆ ) (i ₁ )
(I ₂ ) changes linearly with respect to the change of (ix). In other words, by controlling the current of (ix), the torque vector of the motor linearly changes to the state of →, and it is possible to perform the minute angle drive. The drive current (ix) is controlled by detecting the current (i ₁ + ix) flowing through the phase current detection sense resistor (R ₂ ). The rate of change is the sense resistor (R ₂ ) for phase current detection.
By but towards (i ₀ = state) from the (2i ₀ = state) is to change gradually, during which increases gradually (ix) is _{(0 → 0.8i 0), (} i 1 ) Gradually increases to (i ₀ → 1.2i ₀ ).

This current control is performed by controlling the switching of the output element (Tr ₁ ).

a-3) Similarly, the movement is performed in the order of →→→, which will be described with reference to the equivalent circuit diagram of FIG.

Now, output element (Tr ₈ ) is on, output element (Tr ₉ ), (Tr
FIG. 4 shows the state in which ₁₀ ) is off.

At this time (ix = i ₂ ).

Here, the output element (Tr ₁₀ ) is switching-controlled so as to gradually reduce the current (i ₁ + ix) flowing in the sense resistor (R ₄ ) for phase current detection to (2i ₀ → i ₀ ). (Tr
FIG. 4 shows a state in which ₁₀ ) is completely turned on. Here, (ix = 0).

a-4) Next, switching the output element (Tr ₈ ) so that the current {i ₂ + (− ix)} flowing in the phase current detection sense resistor (R ₅ ) is gradually increased to (i ₀ → 2i ₀ ). Go control
FIG. 4 shows a state in which the output element (Tr ₈ ) is completely turned off.

In this way, by controlling the current flowing from the motor coil control circuit to the motor coils (A) to (E) one after another in each state, a minute angle drive is performed.

b-1) Next, a driving method of the second embodiment circuit will be described.

The connection method of the motor coils (A) ... Used here is called star connection. As in the case described above, each phase in the figure is assumed to excite a positive vector with a current in the direction of the arrow. Sense resistor for phase current detection (R ₁ ) ~
The functions of (R ₅ ) and the total current detection sense resistor (R ₆ ) are the same as in the second invention.

b-2) Here, it is the same as performing the minute angle drive by gradually performing the excitation pattern →→→ ..., This point is the same as the drive method of the first embodiment circuit. Therefore, it will be briefly described.

That is, in the drive circuit (S), the movement to → may be performed by switching control of the output element (Tr ₁ ) by current detection by the phase current detection sense resistor (R ₁ ). Finally, it becomes the state when the output element (Tr ₁ ) is completely turned on.

Next, → is sufficient if switching control of the output element (Tr ₉ ) is performed by the current detection by the sense resistor (R ₅ ) for phase current detection, and when the output element (Tr ₉ ) is completely off. It is in a state.

Similarly, in each state, the motor coil control circuit (M ₁ )
It is the same that the minute angle drive can be performed by controlling the current flowing from the motor coils to the motor coils (A) to (E).

c-1) Finally, a method of driving the circuit of the third embodiment will be described.

In this case, the order of connecting phases is different from that of the embodiment of the driving method of the first embodiment circuit. In the figure, each phase is the same in that a positive vector is excited by a current in the direction of the arrow. The functions of the sense resistors (R ₁ ) to (R ₆ ) for detecting the phase current and the total current are the same as those of the former two.

c-2) Here, it is the same as the former two cases that the minute angle drive is performed by gradually performing the excitation pattern →→→ ..., and will be briefly described below.

In the driving circuit (S) is moved up →, by the current detection of the sense resistor for detecting the phase current (R _1), if we output element (Tr ₉₎ by switching control well, the output element (Tr ₉ ) Is when it is completely off.

Next, → is sufficient if switching control of the output element (Tr ₁₀ ) is performed by current detection with the sense resistor (R ₄ ) for phase current detection, and when the output element (Tr ₁₀ ) is completely turned on. Is the state of.

Similarly, in each state, the motor coil control circuit (M ₁ )
The minute angle drive can be performed by controlling the current flowing from the motor coils (A) to (E).

(Effect) As described above, the driving method of the circuits of the first to third embodiments of the present invention requires only 1/2 the output element for exciting the motor coil as compared with the conventional example, and of course the material cost as well as the assembly There is an advantage that labor cost such as cost can be reduced and the cost can be drastically reduced. Also, the detection circuit detects the voltage change of the total current detection sense resistor for rated current control. , It has the advantage of being able to drive a minute angle with two circuits although it detects the voltage change of the sense resistor for minute angle control, and the rated current flowing in the motor coil is stabilized by the rated current control circuit by the sense resistor for total current detection. Controlled by
Since a DV voltage is applied, a slight ripple occurs only in the phase for which voltage control is performed for minute angle driving. As a result, the amount of ripple generated is that in the conventional example in which ripple occurs over all phases. 1 / n of the output, resulting in less vibration of the stepping motor and stable stop position, and the switching controlled element is a semiconductor chopper in the entire circuit and an output element that performs minute angle drive. Since there are only two in total, there are advantages that the heat loss is small and the switching noise is small as compared with the conventional circuit in which n output elements must be operated.

Needless to say, the stepping motor can be applied to two-phase type to multi-phase type.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 ... Conventional circuit wiring diagram with some parts omitted, FIG. 2 ... Excitation pattern sequence diagram of conventional circuit, FIG. 3 ... One example of driving method of first embodiment circuit Drive circuit connection diagram of the embodiment, FIG. 4 ......... A diagram showing the order of excitation patterns of the drive system of the first embodiment circuit, FIG. 5 ... 4 to 5 phases of the drive method of the first embodiment circuit 6 is an equivalent circuit diagram when excited, and FIG. 6 is an equivalent circuit diagram when excited from 5 phase to 4 phase in the driving method of the first embodiment circuit. FIG. 7 is a driving method of the second embodiment circuit. 8 is a diagram showing the order of the excitation patterns of the driving method of the second embodiment circuit, FIG. 9 is a driving circuit connection diagram of the driving method of the third embodiment circuit, Fig. 10 ... ... Fig. 10 is a diagram showing the order of excitation patterns of the driving method of the third embodiment circuit, (M) ... motor coil control circuit, ( S): stepping motor control circuit, (A) to (E): motor coil, (R): sense resistor, (Tr): output element,
(1) …… Semiconductor chopper, (2) …… Flywheel diode, (3) …… Reactor, (4) …… Smoothing capacitor.

Claims (2)

[Claims] 1. A ring-shaped connection, ... (n-1) → (n) →
Two or more (n) in which the rotor is rotated by minute angles by being sequentially excited as (n-1) → (n) → ...
(N) motor coil control circuit consisting of a series connection body of a phase-phase motor coil and a set of switching elements for selectively connecting the connection points of the motor coil connected in an annular shape to positive / negative of DC current Connected in series with the stepping motor control circuit and the output terminal of the stepping motor control circuit,
A total current detection sense resistor for detecting the total current in order to control the total current, which is the total of the excitation currents flowing in the excited motor coils, to be constant, and each motor coil and each motor coil control circuit When the number of excitation phases changes from (n-1) to (n), the motor coil control circuit connected to the idle phase is turned on / off to flow to the idle phase. ON / OFF control of the motor coil control circuit connected to one exciting phase in which the phase current gradually decreases when the number of exciting phases changes from (n) to (n-1) By gradually decreasing the amount of current flowing in the excitation phase by causing the excitation current, the phase current flowing while gradually increasing or decreasing and the excitation phase adjacent to the one excitation phase in which the idle phase or the phase current decreases are excited. The sum of the current amounts is detected in order to control so that the sum of the gradually increasing / decreasing phase current and the shunting or joining of the adjacent exciting currents, which is the exciting current, gradually increases / decreases at a predetermined rate. A minute angle drive circuit for a stepping motor, which is configured by a sense resistor for detecting a phase current. 2. Radially connected, ... (n-1) → (n)
→ (n-1) → (n) → ... The motor coils of two or more (n) phases that rotate the rotor by minute angles by being sequentially excited, and the radial shape of the motor coils that are radially connected. A stepping motor control circuit composed of (n) motor coil control circuits consisting of a series connection body of a pair of switching elements whose ends are selectively connected to positive and negative DC currents, and a stepping motor control circuit Connected in series to the output end of
A total current detection sense resistor for detecting the total current in order to control the total current, which is the total of the excitation currents flowing in the excited motor coils, to be constant, and each motor coil and each motor coil control circuit When the number of excitation phases changes from (n-1) to (n), the motor coil control circuit connected to the idle phase is turned on / off to flow to the idle phase. ON / OFF control of the motor coil control circuit connected to one exciting phase in which the phase current gradually decreases when the number of exciting phases changes from (n) to (n-1) By gradually decreasing the amount of current flowing in the excitation phase by causing the excitation current, the phase current flowing while gradually increasing or decreasing and the excitation phase adjacent to the one excitation phase in which the idle phase or the phase current decreases are excited. The sum of the exciting currents is detected in order to control the sum of the gradually increasing / decreasing phase current and the shunting or converging adjacent exciting currents to gradually increase / decrease at a predetermined rate. A stepping motor drive circuit comprising a sense resistor for detecting a phase current.