JPH03215193A - Stepping motor driving circuit - Google Patents

Abstract

PURPOSE:To lower the heat generation of a stepping motor by setting absorption voltage due to a counter-electromotive force absorbing circuit, to be low with an absorption voltage switching circuit, while counter-electromotive current along with phase change-over is detected. CONSTITUTION:A counter-electromotive current course is set so that counter- electromotive current may flow to a power source in series, and a counter-electromotive force absorbing circuit 10 for absorbing counter-electromotive voltage and a counter- electromotive current detecting circuit 12 for detecting counter-electromotive current are arranged in the counter-electromotive current course in series, and an absorption voltage switching circuit 11 for switching the adsorption voltage of the counterelectromotive force absorbing circuit 10 is set. Then, just while the counter- electromotive current flowing at the time of phase change-over is detected by the counter-electromotive current detecting circuit 12, the absorption voltage due to the counter-electromotive force absorbing circuit 10 is set to be low voltage by the absorption voltage switching circuit 11, and except at the time of detecting the counter- electromotive current, the absorption voltage due to the counter-electromotive force absorbing circuit 10 is contrived to be set to be high voltage. As a result, the generation heat quantity of a stepping motor can be lowered, and torque can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stepping motor drive circuit.

[Prior Art] FIG. 2 shows a part of a conventional four-phase stepping motor drive circuit. The illustrated part drives the stepping motor together with another set of the same components not shown. FIG. 3 shows a time chart when the four-phase stepping motor shown in FIG. 2 is driven by the two-phase excitation method.

In FIG. 2, this stepping motor drive circuit is
When a start signal is applied from the outside, the stepping motor is driven, and when an external start signal is applied, the driving of the stepping motor is completed. The star 1 signal and the stop signal are applied to the pulse train generator 1 and the overdrive signal generator 3.

The pulse train generator 1 generates a narrow pulse signal at predetermined intervals from when a start signal is applied until when a start signal is applied. The distribution circuit 2 is
Two pulse signals whose levels are inverted every time the output signal of the pulse train generator 1 is applied, which are in antiphase relation to each other, are used to form the pulse signals that are connected to the bases of the pair of transistors 1 to TRI and TR2. There is something to apply to it.

The Ohtribe signal generator 3 takes an H level only from the arrival time of the STAR I- signal to the arrival time of the STO SOPS signal, that is, it outputs a pulse signal that defines the drive period. The inflator circuit 4 outputs a pulse signal that stays at the L level for a certain period of time each time a pulse is output from the pulse train generator 1. Ann l-K-1 and 5 are Oha 1-
The output of the life signal generator 3 is multiplied by 1,000, and the output of the circuit 4 is ANDed. This one output word is used as an on/off control signal for the I-transistor TR4.

A pair of NPN types whose emitters are commonly grounded
The transistors TRI and TR2 are 1-run transistors for phase selection. A pair of phase windings L1 and L of the stepping motor
2 are high-fila wound and one terminal is connected to each other. The other terminals of the phase windings L1 and L2 are connected to corresponding phase selection transistors TRI or TR. 2
connected to the collector.

The output signal of AND gate 5 is applied to the base.
PN type transistor TR4 and this 1H transistor TR
The PNP type transistor TR3 is connected to the collector of 4 through the resistor R2, and the emitter is connected to the power supply -E1. There are 3 transistors for applying power supply voltage. The diode D5 connected in parallel to the run transistors 1 to 1 and j3 is for regenerating the back electromotive current of the phase windings L1 and L2, which are inductive loads, to the power supply 1E1.

Diodes D3 and D4 are connected to each other, and the anodes are connected to the corresponding phase selection transistors TRI and TR2. Zener diode Z connected to the cathode of diode D3 and D4
DI is phase selection transistor 1, transistor T, which is generated from an excessive back electromotive force that occurs when the phase windings L1 and L2 are insufficiently coupled.
R. This is to protect TR1 and TR2.

Next, the operation of the conventional circuit having the above configuration will be explained.

This steering/noving motor drive circuit receives the start signal from the overdrive signal generator 3 and outputs the overdrive signal Sa shown in FIG. The distribution circuit 2 operates by outputting the pulse "II {C signal Sb" shown in FIG. The logic levels of the on/off signals Se and Sf, which have an opposite phase relationship, are inverted as shown in FIG. 2. As a result, the phase selection I-run transistors TR1 and TR2 are turned on and off in a predetermined sequence.

Also, from Multivibrate evening #I4, Figure 3 (C
) A pulse signal Sc that takes the L level for a certain period of time is output from the time when the pulse train signal sb as shown in FIG. 3(d) is applied. Phase selection transistor TRI, 1 of R2
A pulse signal Sd that takes the L level for a certain period of time within the operation cycle is output. When this pulse signal Sd is at the H level, transistors TR4 and TR3 are turned on.

That is, the selected i'' (power supply voltage +E) is applied to the phase windings L1 and L2 via the transistor TR3 after a certain period of time from the switching point of the selected phase windings L1 and L2.

Accordingly, when a certain period of time has elapsed since the start signal was applied [a, the pulse 1 word of the client gate 5 becomes H level], the transistor 1 R3 starts operating, and the At this time, for example, if an ON command and an OFF command are given to the bases of the phase selection transistors TRI and TR2, as shown in FIG. 3(e) and (f), respectively, then as shown in FIG. 3(c+), Phase current 11 flows through phase winding L1 from time ta.

Thereafter, at time tb, when the on/off signal Se for the phase selection transistor TR1 is switched to an OFF command and the on/off signal Sf for the phase selection transistor TR2 is switched to an ON command, the phase selection L transistor TRI is turned off.

12) If the relationship between the soener voltage VZt of the zener diode ZDI and the power supply voltage 1E1 is set to satisfy the following formula VZ10E1>2 ・El - (1), the phase winding L1 Due to the mutual induction between the high-fila wound phase windings L1 and L2, the stored electromagnetic energy is generated at time 1b as indicated by diagonal lines in FIG. 3(h) for phase current j2. empty diode D2,
It is converted into a back electromotive current that is regenerated to the power source 1:-E1 through the path of the phase winding L2, the diode 5, and the power source 1E1.

Note that at time tb, the on/off signal S shown in FIG. 3(f)
f becomes the ON command level, but the selection L/transistor T
R2 does not turn on immediately, and as shown in FIG. 3(h), at the time tc when the back electromotive current flowing through the diode D2 becomes 0, this transistor TR2 turns on, and the phase current flows forward in the phase winding L2. 12 flows.

As described above, by alternately turning on the phase selection transistor TRI or R2, the phase winding L1 or L2
, the combined current of phase currents 11 and 12>
nil-i2 becomes as shown in FIG. 3(i), and the stepping motor is driven by this combined current i1-i2.

[Problems to be Solved by the Invention] However, in the energy regeneration type stethoping motor drive circuit described above, when driving at high speed, the back electromotive force a! % of the time becomes large, and therefore, the reaching value of the phase current becomes small, and the torque generated by the motor decreases.As a countermeasure for this problem, firstly, the power supply voltage is 1E1.
Second, it is possible to increase the current value reached by the phase current by decreasing the resistance value of the phase winding, but either method increases the amount of heat generated by the motor.

The present invention has been made in consideration of the above points, and it is possible to reduce the amount of heat generated by the step-in motor, and therefore, it is possible to increase the torque.
There are attempts to provide energy-saving, energy-regenerating stepping motor drive circuits.

[Means for Solving Problems] In order to solve this problem, the present invention provides a method of driving a step-knopping motor by sequentially switching the n-phase windings and passing current through the same squares of the windings. In addition, the ST/I bink motor drive circuit that regenerates the back electromotive current at the time of phase switching into the power supply is configured as follows, that is, the back electromotive current or the bifilar winding two-phase 141 reference line t'')'t; A back electromotive force connection path was set so that the reverse direction of the current flows in the forward direction, and the back electromotive current flows in series toward the power source.

Further, a back electromotive force absorption circuit that absorbs back electromotive force and a back electromotive current detection circuit that detects back electromotive current are inserted in series in the back electromotive current path. Furthermore, an absorption voltage switching circuit for switching the absorption voltage of the back electromotive force absorption circuit was provided.

Then, the absorption voltage switching circuit sets the absorption voltage by the back electromotive force absorption circuit to a low voltage only while the back electromotive current flowing at the time of phase switching is detected by the back electromotive current detection circuit, and outside of the detection time of the back electromotive current. The absorption voltage by the back electromotive force absorption circuit was set to a high voltage.

[Function] In order to reduce the back electromotive current that flows during phase switching and suppress copper loss in the phase winding, the back electromotive current flows in one direction of the bifilar two-phase phase winding and in the other direction in the positive direction. At the same time, a regeneration path for the back electromotive current was set so that the back electromotive current flows in series toward the power source. That is, the back electromotive current flowing through each phase winding is reduced by causing the back electromotive current to flow through both of the paired phase windings at the time of phase switching.

Even if an attempt is made to suppress heat generation by setting such a new regeneration path, if the absorption voltage is high, heat generation in the portion absorbing the back electromotive force becomes a problem. Therefore, a back electromotive force absorption circuit that absorbs the back electromotive force and a back electromotive current detection circuit that detects the back electromotive current are provided on this regeneration path, and while the back electromotive current accompanying phase switching is being detected, The absorption voltage by the back electromotive force absorption circuit is set low by the absorption voltage switching circuit to suppress the heat generation here.

During the period when no back electromotive current is detected, the back electromotive current is almost 0, so even if a large amount of back electromotive force is absorbed, there is no problem of heat generation. is applied appropriately.

Embodiment 8 An embodiment of the present invention will be described below without reference to the drawings.

Figure 4 is a circuit diagram showing a part of the 1-phase ste-no-pin motor drive circuit according to an embodiment, and Fig. 4 shows a 2-phase excitation system for the 4-phase ste-no-pin motor that is to be driven. This is a time chart 1 of each part when driven by hand. In addition,
Two sets of the horizontal motors shown in FIG. 1 are used to drive a four-phase stethoping motor. Also, the first
In the figure, the same reference numerals are given to the same horizontal components as in the conventional circuit shown in FIG. 2, and the explanation thereof will be omitted.

The step/ping motor drive circuit of this embodiment differs from the conventional drive circuit shown in FIG. 2 in the following points.

That is, the back electromotive force absorption circuit 10 and the back electromotive current detection circuit 12 function as a regeneration path using the Zener diode ZDI for protection of the phase selection transistors TRI and TR2. The difference is that an absorption voltage instant switching circuit 1 is provided which switches the absorption voltage of this back electromotive force absorption circuit 10 between high voltage and low voltage according to the detection output of the back electromotive current detection circuit 12. ，
In this embodiment, the phase winding L1 or 1. which is an inductive load is used. 2
The back electromotive current detection circuit 2 detects the period during which the back electromotive force flowing during switching between the power supply and E1 is regenerated, and the absorption voltage of the back electromotive force absorption circuit 10 is reduced only during that period. is set to a low voltage, and this point is a major difference from conventional circuits.

In FIG. 1, the back electromotive force absorption circuit 10 is of PNP type 1
- Consists of transistor TR5, Zener diode ZD2, and resistor R3. The emitter of the transistor 1'R5 is connected to the phase selection transistors TRI and ' from the back electromotive voltage.
It is commonly connected to the cathodes of diodes D3 and D4 for protecting T'R2, and the collector is connected to the power supply ↑E] through the back electromotive force IFL detection circuit 12, and directly to the annotation of the Zener diode ZD2 and the transistor 1 to transistor 1.゛Connected to the base of R3. The cathode of the Zener diode ZD2 is connected to the base of the transistor R5 and the absorption voltage switching circuit (also connected to the transistor TR5).
Resistor R3 is connected between the emitter and the base ()
IA collection voltage quadruple converter circuit]] is an NPN type I transistor T
R6, and resistors R4 and R5. The l-run transistor TR6 is provided as a switch-notching transistor, the pace of which is connected to the back electromotive current detection circuit 12, and is turned on and off in accordance with the detection output of the back electromotive current detection circuit 12.

The collector of this I~ transistor TR6 absorbs the back electromotive force via the resistor R4.
Connected to the base of R5. That is, it is connected so that the internal state of the back electromotive force absorption circuit IO can be switched. Note that a resistor R5 is connected between the pace and emitter of this I-transistor TR6.

The back electromotive current detection circuit 12 includes two diodes D6 and D7 connected in series between the back electromotive force absorption circuit R]O and the power supply +E1. In addition, it includes a PNP type transistor TR7 and resistors R6 and R7. The voltage across the series circuit consisting of two diodes D6 and L)7 is the voltage across the resistor R.
A voltage is applied between the transistor 1 and transistor TR7 through transistor 6, emitter and resistor.
When a back electromotive current is flowing through +6 and (L)7, the I transistor TR7 is turned on, and when no back electromotive current is flowing, the T transistor TR7 is turned off. Such a detection output (collector voltage TL) is transmitted by transistor TR7.
The voltage is transmitted to the absorption voltage switching circuit 11 via a resistor R7 connected to the collector of the voltage. In addition, back electromotive force absorption circuit 1
The anode of the diode D7 located on the 0 side is also connected to the pace of the I transistor TR3.

Next, the operation of the stepping motor drive circuit according to the embodiment having the above configuration will be explained using FIG.

The stepping motor drive circuit of this embodiment also has a star 1
When one signal is given, the overdrive signal generator 3 outputs the overdrive signal Sa shown in FIG. 4(a), and the pulse train generator 1 outputs the pulse train signal sb shown in 1) in FIG. The distribution circuit 2 executes the driving operation by
As shown in FIGS. (C) and (if), the logic levels of the on/off signals Se and Sf, which have an opposite phase relationship, are inverted. As a result, the phase selection transistors TRI and TR2 are turned on or off in a predetermined sequence.

Further, the multi-vibrator circuit 4 outputs a pulse signal Sc which takes the L level for a certain period of time as shown in FIG. 4(C) from the time when the pulse train signal sb is applied.
As a result, as shown in FIG. 4(d), the AND gate 5 outputs a pulse signal Sd which takes the L level for a certain period of time within one operation cycle of the phase selection transistors TRI and TR2.
is output. When this pulse signal Sd is at H level, both transistors TR4 and TR3 are turned on.

That is, after a certain period of time from the switching point of the selected phase winding L1 or L2, the phase winding L1 is switched through the transistor 1'R3.
Power supply voltage +E1 is applied to L2 and L2.

Therefore, at the time ta after a certain period of time has elapsed since the start signal is given, the pulse No. 12 of the AND gate 5 becomes H level, and transistors 1 to TR3 turn on, and at that time, for example, the phase selection transistor " T”RI and TR2
As shown in FIG. 4(e) and (f), on-off signals Se and Sf for instructing ON command and OFF command are applied to the bases of FIG. A phase current i10 flows through the phase winding L1 from time ta.

Thereafter, the on/off signal Se shown in FIG.
When switching to the L level at b, the phase selection transistor T
RI is turned off. Furthermore, when the output signal Sc of the one-shot multi-vibrator circuit 4 reaches the tb''rL level at this point, as shown in FIG. Transistors TR4 and TR3 are turned off.

At the time t. When the phase selection transistor TR1 is turned off at step b, the electromagnetic energy stored in the phase winding L1 is transferred to the pair of phase windings L1, zi
pI-2. 7) Due to mutual induction, the phase current 110
Figure 4 (F) 71t-hi (h) for and 1?0
Diagonal lines are drawn from the four points tb to diode D2, phase windings L2 and L1, diode D3, back electromotive force absorption circuit & l l O transistor TR5, and back electromotive current detection circuit 12. It is converted into a back electromotive current that is regenerated to the power supply +E1 via the path of the diodes D7 and D6 and the power supply +E1.

In this way, the point where the back electromotive current flows through both of the two phase windings L1 and L2 is that the back electromotive current flows only through one phase winding L1 or L2 due to the function of the Zener diode 2D1 and the diode D5. This is different from conventional circuits.

When a back electromotive current flows through the diodes D7 and D6 of the back electromotive current detection circuit 12, the transistor TR7 is turned on, and a part of the back electromotive current is passed through the resistor R7 connected to the collector as the collector current of the transistor TR7. The current flows further as the base current of the I-transistor TR6 of the absorption voltage switching circuit 11, turning on the I-transistor TR6.

When the absorption voltage switching circuit 11, 1, and transistor 1゛R6 is turned on, a part of the back electromotive current is also transferred to the back electromotive force absorption circuit 10.
It also flows to the transistor TR6 via the emitter, base and resistor R4 of the transistor TR5. That is, a base current flows through the transistor TR5 to turn it on, the transistor TR5 is also turned on, and the emitter-collector voltage of the transistor TR5 becomes a low voltage (approximately 0#0.6V) associated with a PN junction. This voltage is the absorption voltage of the back electromotive force absorption circuit &810 at this time, and the energy loss in the transistor TR5 is as small as in the case of passing through the regeneration path of the conventional circuit.

At time tb, the sum of the magnetic fluxes of the phase windings L1 and L2 is equal to 7 before and after R1 turns off, so
The following formula φ1L・I=2・L・17'2...(2)(
(φ is the total magnetic flux, L is the inductance of the phase windings L1 and L2, and ■ is the phase current value immediately before turning off). The back electromotive current flowing at point b becomes 1 and 2 of the conventional circuit, as shown with diagonal lines in Figure 1 (g) and (i1), and causes each phase winding L1 and L2 to be at a constant current.
L.

Here, the effective value of this back electromotive current is 1,/31″, which is the maximum value.
When approximated by a triangular wave, the copper loss of phase windings L1 and L2 (
The sum of
7'6 (3) (R is the resistance component of each phase winding) It can be expressed as follows. On the other hand, the copper loss of the conventional circuit shown in FIG. 2 is expressed by the following formula: 2P21-R/'3. (4)
It can be expressed as As is clear from these formulas,
In this embodiment, the phase winding I! during the regeneration period of the back electromotive current! L
The copper loss occurring in L and L2 is 17'2 in the conventional circuit.

At time t. a little before the back electromotive current becomes 0. Even though the output signal Sc of the circuit 4 returns to H level, while the back electromotive current is flowing through the diodes D7 and D6, the Hess potential of the transistor T Since the potential is higher than that of R2, R1 to R3 remain in the off state. When the back electromotive current reaches zero at time 1d in FIG. 4, the transistor TR7 of the back electromotive current detection circuit 12
Both the transistor TR6 and the transistor TR6 of the absorption voltage switching circuit 11 are turned off, and the transistor TR3 is turned on to apply the power supply voltage 1E1 to the phase windings LL and L2.

At this time, a back electromotive force of E 1 ,,'2 remains at both ends of the phase winding L1, so that the cathode voltage of the diode D3 is 3·E1. ．． ．． '2, and a voltage El,/2 is applied between the emitter and collector of the transistor TR5 of the back electromotive force absorption circuit 10. However, transistor T
Since R6 is also off, transistor TR5 does not turn on. If the Zener voltage VZ2 of the Zener diode ZD2 is set to VZ2>El as in the conventional circuit, the back electromotive voltage applied between the emitter and collector of the transistor TR5 is lower than the Zener voltage VZ2 of the Zener diode ZD2, so the transistor T.R. 5
becomes active, and the back electromotive current passes through the phase winding Ll, the diode 3, the back electromotive force absorption circuit 10, and the roof of the run transistor 1''R3 and becomes IK.
, the circulation transistor TR3 is electrically connected from 0 to 1, and the power supply voltage +E1 is applied to the phase windings L1 and L2.

Suppose that when the back electromotive current becomes almost 0 and the transistor TR3 turns on, the transistor T of the absorption voltage switching circuit 11
If R6 is in the on state, the transistor TR5 of the back electromotive force absorption circuit 10 remains in the on state, and at that time, the back electromotive force E1/2 remains across the phase winding L1, and the transistor TR3 is turned on. However, the back electromotive current flows through the loop of the phase winding L1, the diode D3, the back electromotive force absorption circuit 10, and the transistor R3, and the back electromotive force of the phase winding L1 is reduced. It is only when the voltage drops to 0■ that the transistor TR3 becomes saturated (almost 0).
■) Conducts. Therefore, during this period, a voltage lower than the power supply voltage 1E1 is applied to the phase winding L2, and the switching of the phase currents cannot be performed smoothly as in the conventional circuit.

Therefore, in order to execute the above-mentioned smooth switching between the phase voltages AilO and j20, the absorption voltage of the back electromotive force absorption circuit]O is changed to LJJ.

At the time t. When the power supply voltage +E1 is applied to the phase winding L2 at step d, the pace of the transistor TR2 is at H level at that time, so 1.
2 is turned on, and thus a phase current 120 flows in the positive direction through the phase winding L2.

As mentioned above, phase selection 1 transistors TRI and TR
2 is turned on alternately, the currents i10 and i20 of the phase windings L1 and L2 are switched, and the combined current i10-i of the phase currents i10 and 120 is changed as shown in FIG.
20 flows in the same way as in the conventional circuit, thus stepping
The motor is driven.

Therefore, according to the above-described embodiment, the absorption voltage of the back electromotive force absorption circuit fi'J 10 is reduced to a low voltage by the absorption voltage switching circuit 11 during the time until the back electromotive current flowing at the time of phase winding switching becomes almost zero. Compared to a conventional circuit in which a back electromotive current flows only through one phase winding, this setting can halve the copper loss in the phase windings L1 and L2 due to back electromotive force residues, and the Reduces fever. It can be done with 2 or so.

C7) Compared to the uncircuited case, the power supply voltage +E1 can be increased and/or the resistance value of the phase winding can be decreased to increase the reaching current value of the phase current. ,
The generated torque can be increased, and the applications of a motor using such a drive circuit can be expanded.

In the above-described embodiment, a drive circuit for a four-phase stepping motor is shown, but the present invention is not limited to four phases, and the present invention can be applied to a drive circuit for a multi-phase stepping motor. However, it is required that the bifilar-wound two-phase phase windings form a pair.

[Effects of the Invention] As described above, according to the stepping motor drive circuit of the present invention, the regeneration path of the back electromotive current is connected in series with one phase winding of the two-phase bifilar winding in the reverse direction and the other in the positive direction. A back electromotive force absorption circuit and a back electromotive current detection circuit are installed in series on the back electromotive current path, and the back electromotive current flowing when the phase winding is switched is detected to be approximately O. −
Since the absorption voltage of the back electromotive force absorption circuit is set to a low voltage by the absorption voltage E7J switching circuit for the time until t, the back electromotive current flows to both bifilar wound phase windings and The copper loss of the stepping motor can be halved, and the heat generation of the stepping motor can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a stepping motor drive circuit according to the present invention, FIG. 2 is a circuit diagram showing a conventional circuit,
FIG. 3 is a time chart of each part of FIG. 2, and FIG. 4 is a time chart of each part of the embodiment shown in FIG. 1... Pulse train generator, 2... Distribution circuit, 3...
O18 Drive signal generator, 4... Eagle shot multi-vibrator circuit, 5... AND gate, 10...
・Back electromotive force absorption circuit, 11...absorption voltage switching circuit, 1
2... Back electromotive current detection circuit, Ll, L2... Phase winding, T
R1, 'D'H2...phase selection transistor, D1,
D2 back electromotive force, dL regeneration diode, D3, D4...
・Aisen Senjaku January Tranmista. 7) Protection diode,
la tb te Timing chart for each part in Figure 2 Figure 3 tc Timing chart for each part in Figure 1 Figure 4

Claims (1)

[Claims] A stepping motor is driven by sequentially switching the n-phase windings and passing a current in the positive direction of the windings.
In a stepping motor drive circuit that regenerates back electromotive current during phase switching into a power supply, the back electromotive current flows through one of the bifilar two-phase windings in the opposite direction and the other in the forward direction, and the back electromotive current A back electromotive current path is set so that it flows in series toward the power supply, and a back electromotive force absorption circuit that absorbs the back electromotive force and a back electromotive current detection circuit that detects the back electromotive current are connected to the back electromotive current path. An absorption voltage switching circuit is installed in series to switch the absorption voltage of the back electromotive force absorption circuit, and only while the back electromotive current flowing at the time of phase switching is detected by the back electromotive current detection circuit, the absorption voltage switching circuit A stepping motor characterized in that the voltage absorbed by the back electromotive force absorption circuit is set to a low voltage, and the absorption voltage by the back electromotive force absorption circuit is set to a high voltage outside the detection time of the back electromotive current. drive circuit.