JPS6066695A - Drive circuit of step motor - Google Patents

Abstract

PURPOSE:To stabilize a step motor without stepout in both normal and reverse rotations at the restarting time of the stopping time. CONSTITUTION:The output C of a normal/reverse rotation timing generator and the output of a distributor 1 are logically applied to an AND gate. phi1, phi2, phi3, phi4 are excitation signals of step motor coils. When a step motor stops rotating and further rotates reversely, the motor is set to non-excited state after the rotor is advanced by 1/2 step angle in a rotating direction before becoming non- excited state, and a stepout is prevented by restarting the motor by resetting the excited state before becoming the non-excited state due to the elimination of a drive command pulse by a timing pulse from a normal/reverse timing pulse generator 3 at the next restarting time.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a drive circuit for a step motor, and particularly to a step motor drive circuit in which the control method frequently switches between forward and reverse rotation, such as positioning control and flow rate control. Be in control.

[Background of the invention]

Recently, the scope of application of step motors has expanded, and they have come to be considered as automotive components, such as being used as microcomputer-controlled actuators for automobile engines, for example. The step motor as an automotive component is often installed in the engine room, and is exposed to harsh environmental conditions, particularly high temperatures.

Further, the step motor is not used in a constantly driven state, and is often stopped to maintain its position.

Therefore, if the excitation current continues to flow through the coil when the motor is stopped, especially in a high temperature atmosphere, the iXA degree of the coil will become quite high and there is a risk of overheating damage.

Also, as the temperature of the coil increases, the resistance of the coil increases and the excitation current decreases, resulting in a decrease in ampere turns and a decrease in output.For this reason, when the motor stops, The step motor drive circuit shown in FIG. 1 prevents the step motor from overheating by cutting off the excitation current and placing it in a non-excited state to reduce wasteful power consumption. In the figure, the terminal is a drive command pulse input terminal, and the step motor performs step operation every time a pulse is input.

Terminal a has a forward/reverse command input terminal, and it is determined whether to perform forward or reverse rotation depending on the one-piece pressure level of this input terminal, that is, IIIGH or LOW. The distribution circuit 1 determines the order of excitation signals to actually excite each phase coil of the step motor based on these two inputs. Also, φ
1. φ2. φ3. Each terminal of φ4 is connected to a coil φl,
Coil φ2. Coil φ3. This is an excitation signal for coil φ4. Further, the drive command pulse input signal yiM serves as an input to the pulse interval detection circuit 2.

The time chart of FIG. 1 is shown in FIG. In the figure, when a waveform as shown in FIG. 2 (5) is input to terminal a and a waveform as shown in FIG. As shown in the waveform, pulse 1...If the interval time is less than or equal to T, the output is HI.
If it is GH%T or more, the output becomes LOW. The fact that the output of the pulse interval detection circuit 2 is LOW means that the drive command pulse has not been received for more than time 7, so after that, the output of the distribution circuit 3, that is, the output of the distribution circuit 3 (see Fig. 2 (c)
g) Excitation signal φ1. φ2. φ3. φ4 is all LOW, and the excitation current is cut off.

In Fig. 2 (LJ V) 0), the broken line waveform is the normal excitation 1;
I! : Decrease. An example of such a publicly known example is Japanese Patent Application Laid-open No. 1983-
There is a publication No. 151319.

However, in such a conventional drive system,
It has the following drawbacks.

The distribution circuit 1 shown in Figure 1 is a circuit that actually determines the order of excitation signals to excite each phase coil of a step motor, and is usually called a two-phase excitation method in which the excitation state is always two-phase excitation. The excitation order is followed.

FIG. 3 is a diagram showing the position and excitation state of the rotor 3-1 of the step motor.

In the figure, each state of rA), [C), [E), and [F] corresponds to the rotor position and excitation state at a certain time in the two-phase excitation method. For example, in Fig. 1, the forward/reverse input terminal a is H
If it is IGH, if the pulses are manually applied to the drive command pulse input terminal one after another, the rotor position and excitation state will be [A] → rc
, ]→[E]→[F]→[A], the rotor 3-1 moves in steps of 1 step angle.

Also, if the forward/reverse rotation input terminal a is LOW, the rotor position and excitation state will change from (A) → [F] → [E] → [C] → [A], and the rotor 3-1 will move one step. Steps in the opposite direction by angle.

The problem here is time 1 shown in the time chart in Figure 2.
At 1 o'clock, that is, when the next pulse does not enter the terminal after one fixed time T, the output of the pulse interval detection circuit 2 becomes LOW and enters a non-excited state. position of the rotor just before time) - MhrmftiB - As r
(”! 1 state flit f aga'L ke, l + g
4) In the mm-1 magnetic state, it is not possible to determine whether the rotor position is in the [B) state or the [D] state, so the rotor position when stopped is not clear.

After this, at time 1 shown in the time chart of Fig. 2, when a pulse is input to terminal A while the forward/reverse input terminal a remains HIGH, the rotor position and excitation state become rE). ] → In the case of [E], the rotor 3-1 is 1/2
CB)
-CE], the rotor 3-1 needs to perform a step operation of 3/2 step angle.

Therefore, compared to the case of CD) → [E), [B] → [E
], it takes time for the step motion of the rotor, and there is therefore a risk that the rotor will not be able to follow changes in the excitation state and will step out. Also, at time 13:00 shown in the time chart in Figure 2, when a pulse enters the terminal after a certain period of time T, the next pulse does not enter and it is in a non-excited state, and then the forward/reverse input terminal a becomes HIGH. Similarly, when the signal changes from LOW to LOW and a pulse is input to the terminal at 12 o'clock, the position of the rotor at the time of stop is not clear, so the rotor position and excitation state in Fig. 3 are [A] → [G'1 → [F')
Or rA) → CI3'J → [F), compared to the case of [A] → [G) → CF '), [A] → [
In the case of 'B] → [F], there is a risk of losing synchronization.

In this way, in a drive circuit like the one shown in Figure 1, if the step motor is stopped for a certain period of time, it will not be energized! Although it has the effect of reducing power consumption, it has the disadvantage that there is a risk of losing synchronization when restarting after the de-energization period.
Furthermore, since the position of the rotor when stopped is not clear, there is a problem in that it is not possible to accurately determine the position of the rotor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a step motor drive circuit that can prevent step-out during malfunction during non-excitation.

[Summary of the invention]

The present invention uses only the drive command signal and forward/reverse command signal of the step motor as input, and makes it into a non-excited state when the stem motor is stopped to maintain the position during positioning control, flow control, etc. Second, the aim is to stabilize the restart in both forward and reverse directions when stopped, thereby preventing step-out.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described.

FIG. 4 shows an example of the implementation of the present invention.

In the figure, terminal a is a forward/reverse command input terminal;
144 motion command pulse input terminal, l is the distribution circuit? PJ1
It is the same as the same symbol in the figure. Further, 3 is a forward/reverse timing generation circuit. When the forward rotation command changes to the reverse rotation command, the forward and reverse rotation command input changes from HI GI (to 1.OW,
If the J rotation command changes to the forward rotation command, the forward/reverse rotation command input is LO.
Changes from W to HIG)I. The forward/reverse timing generation circuit 3 is a circuit that triggers the signal > d multi when the forward/reverse command input changes, such as rising or falling, and generates a timing pulse for a certain period of time. 4 is the output d, e of the distribution circuit 1
, f1g, and a waveform shaping circuit. Output terminal φ1. φ2゜φ3
．． φ4 is step motor coil φ1゜φ21φ respectively
3. It is an excitation signal of φ4, and if the output is HIGH, an excitation current flows, and if it is LOW, no excitation occurs.

FIG. 5 shows operating waveforms of the embodiment shown in FIG.

In the figure, a terminal, bζf! a, l for li child respectively
), the output waveform C of the forward/reverse timing generation circuit will be generated at the rising edge of the b input, that is, at time 114.
A trigger is applied at the falling edge of the clock, that is, at time '8r'111, and a timing pulse is generated for a certain period of time TM. In this case, the output waveforms of the distribution circuit 1 are outputted as d+e+'+g waveforms, respectively, according to the two-phase excitation method.

The aforementioned forward/reverse timing occurrence +1? ! The waveform obtained by ANDing the output C of the circuit and each of the outputs d+e+'rg of the distribution circuit 1 is the waveform h+i+J+. This means that the output waveforms of the distribution circuits h+' and j+ are taken out only for a certain period of time TM after forward/reverse switching, while the output waveforms of the distribution circuit l are triggered by the differentiating circuit 4, which is triggered at the rising edge of each output waveform.
It was done manually.

m, n, 0 waveforms are output. This differentiator circuit 4 is triggered at the rising edge for a certain period of time TN (this is determined by CN and N). If it falls earlier, it outputs the same as the input, and if it falls later than TN, it outputs the falling signal after TN has elapsed. To become,
The m, n, o waveforms are 1 (the time in the IGII state is less than TN. In other words, unless the movement command pulse is input to the distribution circuit, the output of the distribution circuit will not change, so 1-I I
If it is GH, it will remain in the HIGH state, but the differential circuit 4
In order to pass, the IrIGH state is rll, and in order to become a LOW state later, the last drive command pulse is input and after TN, all outputs become LOW and become a non-excited state.

Here, if we OR the "+'+J+ k waveform and each of the re, m, n, and o waveforms, the excitation signal waveforms φ1.φ2゜φ3.
It becomes φ4.

Figure 6 shows the rotor position and excitation state! Sweetness is shown. Now, a case will be explained using the time chart shown in FIG. In Figure 6, the forward and reverse rotation of the rotor is indicated by arrows, and the forward and reverse rotation command input terminal a is HIGH.
If it is H, it is a forward rotation command, and if it is LOW, it is a reverse rotation command.

Now, at time t2, when a drive command pulse is input with a forward rotation command and no pulse is input for a while and there is no forward/reverse switching, the state diagram of the rotor position and excitation at s'2 is shown in Figure 6. If [I(]), the excitation signal φ at t1
2's HIG [I state has passed for TN, so the excitation signal φ2 becomes LOW, and the rotor position and excitation state become [■].

After this, at 14:00, the excitation signal φ3 goes from HIGH to TN, so the excitation signal φ3 also goes LOW.
Even if the state is de-energized, the rotor position does not change because it is a magnetically stable state, so the rotor position and excitation state are rJ
). This is done by switching from 2-phase excitation to 1-phase excitation before the drive command pulse runs out and the state becomes non-excited, and the rotor is advanced by a 1/2 step angle in the direction of rotation before returning to the non-excited state. Especially for positioning the rotor. Therefore, even more time passes and time 15
In other words, when a new drive command pulse enters and restarts, the excitation signal φ4 becomes HIGH, and the rotor position and excitation state become [K].When the next pulse enters at 16:00, it returns to normal two-phase excitation again at CL. ). Therefore, when restarting, the rotor is reliably rotated once in the forward rotation direction while being energized in one phase.
This is a step angle operation.

Next, if a drive command pulse is input in the reverse direction at the time, and no pulse is input for a while after that, and the forward/reverse rotation changes from a reversal command to a forward command, the rotor position at '11 o'clock and the excitation If the state diagram is [L] in Figure 6,
tl! At this time, since the JIIGH state of φ2 has passed TN, the excitation signal φ2 becomes LOW, and the rotor position and excitation state become (K).

After this, at time t13, since the HIGH state of the excitation signal φ1 has passed TN, the excitation signal φ1 also becomes LOW, and all the excitation signals become LOW, that is, a non-excitation state, and the [K] state is a magnetically stable state even if it becomes non-excitation. Therefore, the rotor position does not change, so the rotor position and excitation state become [M].

Up to this point, it is the same as in the case without forward/reverse switching, and the P rotor is positioned by changing from two-phase excitation to one-phase excitation and then non-excitation.

Further, at time 114 when the forward/reverse switching occurs, the forward/reverse command signal changes from LOW to HIGH, and a forward/reverse timing pulse is generated by TM.During this time, each output of the distribution circuit 1 is taken out and used as an excitation signal, so the rotor The position and excitation state are the same as at 112 o'clock [L].

This means that the excitation state before the non-excitation state when the drive command pulse disappears is restored from the non-excitation state when the forward/reverse rotation command signal changes.

This is because at time tts, that is, when a new drive command pulse is input, the forward/reverse switching has been performed, so the rotor position and excitation state become [N], and the rotor movement is reversed, but the non-excitation state [M ] It is empty.

Therefore, at time t14, tI! If the excitation state at time is the [L] state restored, normal two-phase excitation will occur even if the rotor is reversed to the CN] state at time t's.

In this way, if the drive circuit shown in Fig. 4 is used, when the step motor stops rotating and then restarts in the same rotational direction, the stepper motor will rotate one more time in the rotational direction before becoming non-excited.
By advancing the rotor by a /2 step angle and then setting it in a non-excited state to position the rotor when it is stopped, tax adjustment at the next restart can be prevented.

In addition, when the step motor stops rotating and then rotates in the opposite direction, the rotor is positioned in the same way when it stops, and when the forward/reverse command is switched, the previous two-phase excitation state is restored and the next Prevents loss of synchronization when restarting.

Therefore, according to this embodiment, the step motor moves to a position t.
When the motor is stopped to hold the position during i-determining control, flow rate control, etc., the 7 component heat of the motor can be reduced to Bfi+ by leaving it in a non-excited state.
11. Without using the software program of the Zusuke microcomputer, it is possible to stabilize the restart after stopping in both forward and reverse directions, eliminating the risk of step-out, and reducing the burden on the step motor control program. There are two major effects that can be achieved.

Therefore, when a step motor is used as an automotive component such as an actuator for controlling an automobile engine using a microcomputer, it is possible to improve reliability and prevent a reduction in output by preventing unnecessary heat generation of the step motor. It is possible to reduce the program capacity for controlling the step motor, making it optimal as a step motor drive circuit.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent step-out during re-operation after non-excitation.

[Brief explanation of drawings]

Fig. 1 is a drive circuit diagram of a conventional step motor, Fig. 2 is a time chart of Fig. 1, Fig. 3 is a diagram showing the rotor position and excitation state of the step motor, and Fig. 4 is an embodiment of the present invention. FIG. 5 is a time chart of the embodiment shown in FIG. 41, and FIG. 6 is a diagram showing the rotor position and excitation state of the step motor. 1...Distribution circuit, 2...Pulse interval detection circuit, 3.
...Correct! Figure 2 fAJ Figure 5 Figure Z

Claims (1)

[Claims] 1. Input the drive command signal and forward/reverse command signal? ,
! In a step motor drive circuit that excites a step motor by the output of a distribution circuit that determines the excitation order of coils between several times, when the pressure level of the forward/reverse command signal changes, each output signal of the distribution circuit a return circuit that takes out the signal for a certain period of time, and a cutoff circuit that cuts off the output signal of each of the distribution circuits after a certain period of time,
A drive circuit for a step motor, characterized in that an output signal obtained by ORing each output of the return circuit and each output of the cutoff circuit is used as an excitation signal.