JPS59123497A - Switching drive circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a switching drive circuit (1) that can efficiently switch a circuit with an inductance load, such as a stepping motor drive circuit or a chopper circuit with an inductance load. Two matters.

(2) Background technology and its problems In switching drive circuits for inductance loads such as stepping motor drive circuits and chopper circuits with inductance loads, it is necessary to absorb the energy of the back electromotive force generated in the inductance of the load during switching. is necessary.

To explain the driving circuit of a stepping motor as an example, as shown in FIG. Coil L1 and second coil L.

The first coil L is bifilar-wound so that the inductance values of both coils are the same (in Figure 1, the one wound around the magnetic pole A is shown as a representative).
A common terminal T is connected to the power source E so that the second coil L2 and the second coil L2 have two opposite polarities. As shown in Figure 1, the terminals 'I'' and T2 connected to the switching circuit are one common terminal and the other connecting terminal, each serving as one end of a bifilar winding.

Turn off the current supplied to the first coil L, and switch the current to the coil of another magnetic pole, for example, the first coil of magnetic pole B (= When the current is switched, the polarity of the valley magnetic pole is switched, and the rotor R moves one step. Rotate.

FIG. 2 shows a drive circuit that switches between the first coil L1 and the second coil L2, and TR, TR2 are switching transistors.

- When switching transistor TR1 is turned from ON to OFF, a large back electromotive force is generated in the first coil L1, and the switching transistor TR and the first coil L are
1 as well as other parts and equipment.

Therefore, conventionally, in order to absorb the energy of this large back electromotive force and remove the damage and interference caused to others, diodes (-, D, D) and Zener diodes (2, 2) were used, as shown in Figure 2. ), the first coil L1 and second coil L2+2 are connected in parallel as shown in the figure, or a series circuit of resistors (R, R) and capacitors (C, C) is connected in parallel. A method was taken to do so.

However, this method requires an element that can withstand a large back electromotive force and its energy consumption, heat generation due to the consumption of reverse power becomes a problem, and the There were problems such as poor efficiency.

(3) Purpose of the Invention The present invention aims to effectively utilize the energy associated with the back electromotive force generated by the coil (2) by returning it to the power supply during switching. It is an object of the present invention to provide a switching drive circuit that is both efficient and efficient.

(4) Structure of the Invention In order to achieve the above object, the switching drive circuit of the present invention includes a first coil and a second coil, each of which has a common magnetic flux, is wound with opposite polarity, and has a common terminal connected to a power source.
a first switching means and a second switching means, each of which is connected to a common terminal and an opposite terminal of the first coil and the second coil, and when one turns from on to off, the other is in the off state and first unidirectional conduction means and second unidirectional conduction means connected in parallel to said first switching means and said second switching means and with conduction directions opposite to said switching means, respectively. When one of the switching means is turned off, the accumulated force of the two connected coils is transferred to the other switching means (the back electromotive force energy through the two connected coils and the unidirectional conduction means). (5) Embodiment of the Invention FIG. 3 shows one embodiment of the present invention.

In Figure 3A, E is a power supply, Ll and L2 are first and second coils, TR1 and TR2 are switching transistors, F is an iron core, D and D4 are diodes to improve switching characteristics, and Rg is a switching transistor. The common emitter resistors D and D2 to improve the characteristics are a series circuit of a switching transistor and a diode (two connected in parallel. A diode with little accumulated charge, such as a Schottky diode).

The first and second coils L1 and L2 are wound on an iron core F (two turns with opposite polarity to each other), and are connected to a diode D,
and D2 are the switching transistors and diodes to which they are connected in parallel (TR, , , TR2 and D4
) are connected so that the conduction direction is opposite to the conduction direction. This diode D1. The reason why a diode with a small amount of accumulated charge, such as a Schottky diode, is used as D2 is to shorten on and off times and improve switching characteristics.

Next, the operation of FIG. 3A will be explained using the switching transistor TR.
Taking as an example the case where the switching transistor TR is turned on and off when the switching transistor TR is off (-), this will be explained with reference to the waveform diagram in FIG. 3B.

When the switching transistor TR is turned on after a time T, the current L k# m of the first coil L
``As shown in Figure B (=rises).When switching transistor TR is turned off at time T2 (2).

A back electromotive force tB having the polarity shown is generated in the second coil L by electromagnetic induction. Since the current flowing through the first coil L1 suddenly becomes zero, the value of the back electromotive force 6B becomes much larger than the value of the power source E.

Therefore, as shown in FIG. 9, the common terminal T of the second coil L2. A current flows in the path of →power supply E→diode D→connection terminal T2 of second coil L2 with a waveform shown in FIG. 3B.

In this way, the energy stored in the first coil L1 is returned to the power source E from the second coil L2 and regenerated when the switching transistor TR is turned off. If it has the characteristics of
This is effective because the energy supplied by this back electromotive force C2 becomes power source energy and is regenerated as it is.

At time T3, when the switching transistor TR is turned on, the first coil L is turned on, as shown in FIG. 3B.
1+2 current 11 (=current flows, and current 2 of the second coil L2 becomes zero.

The following 9 hours T...T5. When the switching transistor TR is turned on and off at T6..., the above-described operation is repeated.

Note that the same switching operation is performed even without the emitter resistance Rg in FIG. 3A (=).The emitter resistance R,
If there is an emitter resistor R, the sensitivity of the switching transistor TR decreases, so the level of the control signal supplied to the base must be increased accordingly, but the switching characteristics are improved compared to the case without the emitter resistor R.

In the above description, the switching transistor TR2 is in an off state and the switching transistor TR is turned on and off, but conversely, the switching transistor TR1 is in an off state.

When the switching transistor TR2 is turned on or off, the currents ■1 and ■2 are exchanged, and the first coil L is switched.

(A current due to the generated back electromotive force (2) flows through the diode D, but its operation and the operation waveform of each current are the same as in FIG. 3B.

As explained above, if the energy associated with the back electromotive force is returned to the power source E using the circuit configuration shown in Figure 3A, the elements necessary for consuming the back electromotive force will no longer be necessary, and the energy of the back electromotive force will be reduced. Since the consumption is low, there is no need to worry about heat generation or damage.

Furthermore, the energy consumption of the back electromotive force is small, and the efficiency of the power supply is improved by the amount of energy returned by this back electromotive force.

FIG. 4 shows another embodiment of the switching drive circuit of the present invention.

In Fig. 4A, Zl and Z are Zener diodes, and a switching circuit (TR, and D3゜TR2 and D4) consists of a series circuit of a switching transistor and a diode.
) is connected in parallel to the unidirectional conduction circuit (Ul-U2)
except that it consists of a series circuit of a diode and a Zener diode (D+ and Zl, D2 and Z2).

It has the same circuit configuration as FIG. 3.

The operation and effects of FIG. 4A are basically the same as those of FIG. 3A, but when Zener diodes Zlsz2 are connected in series with diodes D and D2, the switching response characteristics are changed by the Zener diodes. Since the dependence on the power source is eliminated, the switching characteristics are further improved than in the case of FIG. 3A.

FIG. 4B shows the first and second coils L1. This shows the switching operation waveforms of L, (current flow, and current flow).

In addition, the case of Fig. 4A is the same as the case of Fig. 3A (=,
The emitter resistor Re may be removed.

FIG. 5 shows two further embodiments of the switching drive circuit of the present invention.

In FIG. 5, TR and TR4 are switching transistors, and Zener diodes 21.2. The switching transistor TR, and TR4 are connected to the diode D1゜D,
4 except that they are connected in the same conduction direction to form unidirectional conduction circuits U, , U, respectively. Similarly, the common emitter resistance R can be eliminated.

Like a chopper circuit (two first and second coils L,.

When the current flowing through L2 is large, a diode and a Zener diode (D't and Z, . . .
Since the current flowing through D2 and Zt also increases, the power consumed therein cannot be ignored. Especially Zener diode 2. , 2. The terminal voltage of the diode D,, D,
Since the power loss is much larger than that of , the power loss cannot be ignored.

Therefore, in this embodiment, as shown in FIG. 5, Zener diodes 2. , 2. In addition, switching diode T
R, and TR are connected in parallel so that the current due to the back electromotive force passes through the switching diode TR4 (or TR) instead of passing through the Zener diode Z2 (or Zt).

The operation shown in FIG. 5 will be described by taking as an example the case where the switching transistor TR2 is in the off state and the switching transistor TR is turned on and off, as in the case up to now.

In this case, the switching transistor TR is off;
TR4 is controlled to be in the on state.

When the switching transistor TR is switched from on to off, the current 11 is turned off.

A back electromotive force gB is generated in the second coil L with the polarity shown, and the current flows toward the power source E.

The power supply engineer, at the first moment, the second coil L2 → power supply E
→ Zener diode Z2 → diode D2 → second coil L2, but when a voltage is generated in Zener diode Z, switching transistor TR immediately becomes conductive, and the subsequent current ①.

Most of the current flows through the switching transistor TR.

That is, since the current flowing through the Zener diode Z is small enough to maintain its constant voltage characteristics, its power consumption is also extremely small and no problem occurs.

The other operations and effects of the currents I, I2 flowing through $1 and the second coils L, I, are the same as in the case of FIG.

The switching transistor TR1 is in an off state,
When turning on and off the switching transistor TR2, the switching transistor TR4 is turned off and the switching transistor TR2 is turned on and off.
R, is turned on.

Furthermore, when the currents I,, I, flowing through the first and second coils L, L2 are small, if both the switching transistors TR3 and TR6 are turned off, the circuit configuration becomes the same as that shown in FIG. The same operation as in Figure 4A can be performed.

In the above explanation, we took as an example a case where the first and second coils are wound in a bifilar manner with opposite polarity around one magnetic pole, such as a stepping motor drive circuit. The invention is, of course, not limited to one in which the first and second coils are bifilar wound.

Furthermore, in the present invention, the first and second coils may have a common magnetic flux and have opposite polarity (= two turns,
It is not necessary that the first and second coils are wound together (two turns) on one magnetic pole.

(6) Effects of the Invention As is clear from the explanations above, the switching drive circuit of the present invention provides the following first-order effects.

■ There is no need to provide an element that can withstand the reverse voltage of the back electromotive force and consumes its energy. This element requires a high reverse withstand voltage and a large power capacity.
It is more expensive than the diodes and transistors of the unidirectional conduction circuit used in the present invention.

■ Since the energy consumption of back electromotive force in the unidirectional conduction circuit is small, there is no risk of heat generation or damage.

(2) The energy consumption of the back electromotive force is small, and the efficiency of the power source is improved by the amount of energy returned to the power supply C by this back electromotive force.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a stepping motor, and FIG. 2 is an explanatory diagram of a conventional stepping motor drive circuit. FIG. 3 is an explanatory diagram of one embodiment of the switching drive circuit of the present invention, FIG. 4 is an explanatory diagram of another embodiment of the switching drive circuit of the present invention, and FIG. 5 is an explanatory diagram of another embodiment of the switching drive circuit of the present invention. It is an explanatory view of another example. In the figure, Ll is the first coil and L is the second coil. TR,, TR2, TR3, TR4 are switching transistors, U,, U2 is a unidirectional conduction circuit, D,
, D2 is a diode, 2. , 22 is the Zener diode l"l γ is the resistor, 0.0' is the capacitor, 9 is the emitter resistor, E is the power supply, F is the iron core, A,
A, B, B, C, C are magnetic poles. R is rotor + L + I2 is current t'B is back electromotive force. 2 years old, 2 years shy

Claims (4)

[Claims] (1) A first coil and a second coil that share a common magnetic flux and are wound with opposite polarities and have a common terminal connected to a power source, and a terminal that is opposite to the common terminal of the first coil and second coil. a first switching means and a second switching means, each connected to said first switching means and said second switching means, the other being in an off state when one goes from on to off; a first unidirectional conducting means and a second unidirectional conducting means each connected with a direction of conduction opposite to that of the switching means, when one of the switching means is turned off;
It is a switching device characterized in that the accumulated power of two connected coils becomes back electromotive force energy and is supplied to the power source via the coil connected to the other switching means and the unidirectional conduction means. drive circuit. (2) The switching drive circuit according to claim 1, wherein the unidirectional conduction means is a diode. (3) The switching drive circuit according to claim 1, wherein the unidirectional conduction means is a series circuit of a diode and a constant voltage element. (4) The unidirectional conduction means comprises a diode and one constant voltage element connected in series, and two switching elements connected in parallel to the constant voltage element. The switching drive circuit according to item 1.