JP2003133932A - Driving circuit for semiconductor switch element and semiconductor relay using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the switching time. SOLUTION: A driving circuit is provided with a primary side circuit 10 composed of a primary winding N1 of transformer T, a light emitting element 11, a resistor R1, and a series circuit of a driving power 12, and a secondary side circuit 20 composed of a series circuit of a secondary winding N2 of the transformer T and a photovoltaic element 21, and a control circuit 30. The capacitor between terminals of the photovoltaic element 21 and the capacity of input of a semiconductor switch element 22 are charged together with not only the photovoltaic generated at the photovoltaic element 21 but also an induced electromotive force generated at the secondary winding N2 of the transformer T. Therefor a switching time necessary for turning on the semiconductor switch element 22 are shortened as compared with the conventional example by only the photovoltaic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a semiconductor switch element and a semiconductor relay using the drive circuit.

[0002]

2. Description of the Related Art In recent years, there is an increasing need for semiconductor switches as switching elements that can transmit high-frequency analog signals with high accuracy and can be turned on and off at high speed. Such a semiconductor switch is composed of a light emitting element such as a light emitting diode, a photovoltaic element such as a photodiode, and a pair of MOSFETs connected in anti-series, and is turned on and off by the output of the photovoltaic element. A semiconductor relay provided with a switch element is known.

A circuit diagram of this type of semiconductor relay is shown in FIG. 10 (see Japanese Patent Laid-Open No. 63-153916). Figure 10
The semiconductor relay shown in FIG. 1 includes a primary side circuit 10 including a light emitting element 11 formed of a light emitting diode, a secondary side circuit 20 including a photovoltaic element 21 that is optically coupled to the light emitting element 11 to generate a photoelectromotive force, and a gate. Two n-channel MOSFETs in which terminals (hereinafter abbreviated as gates) and source terminals (hereinafter abbreviated as sources) are commonly connected to each other
And a semiconductor switching element 22 composed of 22a and 22b, which transmits direct-current power from the primary side circuit 10 to the secondary side circuit by optical coupling to generate electromotive force of the photovoltaic element 21 included in the secondary side circuit 20. In response, the semiconductor switch element 22 is configured to be turned on / off. The semiconductor switch element 22 includes n-channel MOSFETs 22a, 22
The drain terminals of b (hereinafter abbreviated as drains) are respectively connected to output terminals (not shown).

Here, a drive power source 12 is connected between both ends of the light emitting element 11 via a resistor R1. The drive power supply 12 is composed of a pulse power supply that outputs a pulse voltage. Further, between the connection point between the gates and the connection point between the sources in the semiconductor switch element 22 described above, a normally-on type (depletion type) n-channel MO having a bias resistor R2 connected between the gate and the source.
The SFET 23 is connected. This normally-on type n-channel MOSFET 23 is a semiconductor switching device 2
It is provided to pull out the gate charge of each of the second MOSFETs 22a and 22b. Further, between the gate and source of the normally-on type n-channel MOSFET 23,
N-channel MOSFE with shorted gate-drain
The source and drain of T24 are connected.

In the semiconductor relay described above, the driving power source 12, the resistor R1, the light emitting element 11, the photovoltaic element 21, the normally-on type n-channel MOSFET 23, the bias resistor R2, and the n-channel MOSFET 24 drive the semiconductor switch element 22. The semiconductor switch element 22 constitutes a circuit and can conduct and block AC power.

The operation of the above drive circuit will be described below.

First, the operation when the semiconductor switch element 22 is shifted from the off state to the on state will be described.

When a forward current flows from the driving power source 12 to the light emitting element 11 through the resistor R1, the light emitting element 11 emits light and the photovoltaic element 21 generates photovoltaic power. The current due to this photovoltaic power is initially the positive electrode of the photovoltaic device 21-the drain of the normally-on type n-channel MOSFET 23-
It flows in the path of the source of the normally-on type n-channel MOSFET 23-the bias resistor R2-the negative electrode of the photovoltaic element 21. This current causes a voltage drop across the bias resistor R2 between the gate and the source of the n-channel MOSFET 23 in the direction of reverse bias, and the bias resistor R2.
When the voltage across both ends exceeds the threshold voltage of the n-channel MOSFET 23, the n-channel MOSFET 23 has a high impedance. After this, most of the current due to the photovoltaic power of the photovoltaic element 21 is the positive electrode of the photovoltaic element 21-the gate of the n-channel MOSFETs 22a and 22b-the source of the n-channel MOSFETs 22a and 22b-the bias resistor R2-the photovoltaic. It flows in the path of the negative electrode of the power element 21 to charge the gates and sources of the n-channel MOSFETs 22a and 22b in the direction of forward bias. When this charging voltage exceeds the threshold voltage of each n-channel MOSFET 22a, 22b, each n-channel MOSFET 22a, 22b
Turns on. Furthermore, each n-channel MOSFET
After the gate-sources of 22a and 22b are completely charged, the current due to the photovoltaic power is passed through the normally-on type n-channel MOSFET 23 having high impedance,
The current continues to flow in the path of the positive electrode of the photovoltaic element 21, the drain of the normally-on type n-channel MOSFET 23, the source of the normally-on type n-channel MOSFET 23, and the bias resistance R2-the negative electrode of the photovoltaic element 21. This is because the normally-on type n-channel MOSFET 23 reaches the equilibrium state with a certain impedance because the current flowing therethrough maintains the high impedance state due to the voltage drop in the bias resistor R2. In this state, most of the current flowing through the bias resistor R2 comes to flow through the n-channel MOSFET 24 that is connected in parallel and adjusted to a medium impedance, and the voltage drop of the bias resistor R2 causes the n-channel M to flow.
The bias voltage between the gate and the source of the OSFETs 22a and 22b is lowered to decrease the n-channel MOSFETs 22a and 22b.
The on-resistance of b is prevented from increasing.

Next, the operation of shifting the semiconductor switch element 22 from the on state to the off state will be described.

When the output voltage of the driving power source 12 becomes 0V and the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases. Therefore, the voltage drop of the bias resistor R2 is reduced, and the normally-on type n-channel MOSFET 23 is
Becomes a low impedance state. Then, n channel M
The charge accumulated between the gate and the source of the OSFETs 22a and 22b and the charge accumulated between the positive electrode and the negative electrode of the photovoltaic element 21 are the n-channel MOSFET 23.
Through the n-channel MOSFETs 22a, 2
When the gate-source voltage of 2b falls below the threshold voltage, each n-channel MOSFET 22a, 22b is turned off.

The semiconductor relay configured as described above is
Each n-channel MOSFET 2 of the semiconductor switch element 22
N-channel MSOFT when 2a and 22b are turned on
The gate-sources of T22a and 22b operate so as to be charged in a relatively short time and turned on at high speed, and most of the output voltage of the photovoltaic element 21 even after charging is completed is the gate of the n-channel MOSFETs 22a and 22b. The n-channel MOSFETs 22a, 22 applied between the sources
It operates so that b is kept at a low on-resistance. On the other hand, even when turned off, the n-channel MOSFET 22
The charge accumulated between the gate and the source of a and 22b is discharged in a relatively short time and turned off at a high speed.

[0012]

However, at present, since the power transfer efficiency due to the optical coupling between the light emitting element 11 and the photovoltaic element 21 is very low, less than 1%, the semiconductor switching element 22 is turned on and off. It is difficult to further reduce the time required for switching (switching time).

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a drive circuit for a semiconductor switch element capable of shortening a switching time and a semiconductor relay using the drive circuit. .

[0014]

In order to achieve the above object, the invention of claim 1 comprises a primary side circuit and a secondary side circuit which are optically coupled to each other, and the primary side circuit is connected to the drive power source through the primary side circuit. In a drive circuit for transmitting electric power to a secondary side circuit using light as a medium and switching the semiconductor switch element by the secondary side circuit using the transmitted electric power, in addition to the electric power transmission using the light medium as a primary side It is characterized in that it is provided with a power supply means for supplying the input power to the circuit to the secondary side circuit, and by supplementing the power transfer by the optical coupling with the power supply means, it is possible to shorten the switching time of the semiconductor switch element. A drive circuit can be realized.

According to a second aspect of the invention, in the first aspect of the invention, the power supply means supplies power to the secondary side circuit in response to a change in the drive voltage applied from the drive power source to the primary side circuit. Is characterized by comprising electromagnetic coupling means for electromagnetically coupling the primary side circuit and the secondary side circuit, and by supplementing the power transmission by optical coupling with the electromagnetic coupling means, it is possible to shorten the switching time of the semiconductor switch element. A drive circuit can be realized.

According to a third aspect of the invention, in the second aspect of the invention, the electromagnetic coupling means is a transformer.
The same operation as the invention of claim 2 is achieved.

According to a fourth aspect of the present invention, in the third aspect of the invention, the primary side circuit comprises a series circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and the secondary side circuit. Is composed of a series circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element, and the photovoltaic generated in the photovoltaic element when power is supplied from a driving power source and the secondary winding of the transformer In addition to the action of the invention of claim 3, the polarity of the induced electromotive force is the same as that of the induced electromotive force.
The timing of power transmission by optical coupling and the timing of power transmission by magnetic coupling naturally coincide with each other, which facilitates control.

According to a fifth aspect of the present invention, in the third aspect of the invention, the primary side circuit is configured by connecting a light emitting element that emits light by application of a driving voltage and a primary winding of a transformer in parallel to each other, and a secondary side. The circuit is composed of a series circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element, and the photovoltaic generated in the photovoltaic element when power is supplied from a drive power source and the secondary winding of the transformer In addition to the action of the invention of claim 3, the current flowing through the light emitting element and the current flowing through the primary winding of the transformer are individually adjusted. can do. as a result,
It is possible to design power transmission by optical coupling and power transmission by electromagnetic coupling independently and individually.

According to a sixth aspect of the invention, in the third aspect of the invention, the primary side circuit is composed of a series circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and the secondary side circuit. Is composed of a parallel circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element. The photovoltaic generated in the photovoltaic element when power is supplied from a driving power source and the secondary winding of the transformer It has the same polarity as the induced electromotive force to be induced, and has the same effect as the invention of claim 3.

According to a seventh aspect of the present invention, in the third aspect of the invention, the primary side circuit is composed of a parallel circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied. Is composed of a parallel circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element. The photovoltaic generated in the photovoltaic element when power is supplied from a driving power source and the secondary winding of the transformer In addition to the action of the invention of claim 3, the polarity of the induced electromotive force is the same as that of the induced electromotive force.
The current flowing through the light emitting element and the current flowing through the primary winding of the transformer can be individually adjusted. As a result, it is possible to design the power transfer by optical coupling and the power transfer by electromagnetic coupling independently and individually.

The invention of claim 8 is characterized in that, in the invention of claim 4 or 6, the primary side circuit comprises a rectifying element connected in antiparallel with the light emitting element. In addition to the above action, when the semiconductor switch element is turned off, a reverse current is applied to the primary winding of the transformer through the rectifying element, so that the secondary winding of the transformer induces an induction in the direction opposite to that at turn-on. Electric power is induced, and the switching time when the semiconductor switch element is turned off can be shortened.

The invention of claim 9 is the invention of claim 4 or 6 or 8.
In the invention of claim 1, the primary side circuit is provided with a capacitive element connected in parallel with the light emitting element, and when the drive voltage rises, a large current flows to the primary winding of the transformer through the capacitive element having a low impedance. Flowing transformer 2
A large induced electromotive force can be induced in the secondary winding, and the switching time can be further shortened. Further, after the driving voltage rises and becomes stable, almost no current flows through the capacitive element, and the power consumption in the primary side circuit can be reduced.

According to a tenth aspect of the present invention, in the fifth or seventh aspect of the present invention, the timing at which the induced electromotive force is induced in the secondary winding of the transformer is not earlier than the timing at which the photovoltaic element is generated in the photovoltaic element. The control means for controlling the switching element is provided to prevent the charged electric charge of the photovoltaic element from being discharged due to the induced electromotive force induced in the secondary winding of the transformer, further shortening the switching time. it can.

According to a tenth aspect of the present invention, in the tenth aspect of the present invention, there is provided means for shortening the time for which the induced electromotive force is induced in the secondary winding of the transformer to be shorter than the time for the photovoltaic element to generate the photoelectromotive force. In addition to the operation of the invention of claim 10, the power consumption in the primary side circuit can be reduced.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, there is provided means for making the rising edge of the drive voltage applied from the driving power source to the primary winding of the transformer steep and relatively gradual. Claim 1 characterized in that
In addition to the effect of the first aspect of the invention, it is possible to suppress the induced electromotive force having a polarity opposite to that of the photoelectromotive force induced in the secondary winding when the drive voltage applied to the primary winding of the transformer falls. It is possible to suppress the voltage fluctuation of the secondary side circuit during the constant time.

According to a thirteenth aspect of the present invention, in the invention of the twelfth aspect, when the power supply from the driving power source is stopped
The induced electromotive force induced in the secondary winding has a polarity opposite to that of the photovoltaic force generated in the photovoltaic element when power is supplied from the driving power source, and in addition to the action of the invention of claim 12, a semiconductor The discharge time of the charge accumulated in the gate electrode of the switch element and the charge accumulated in the photovoltaic element can be promoted to shorten the switching time when the semiconductor switch element is turned off.

According to a fourteenth aspect of the present invention, in the invention according to any one of the tenth to thirteenth aspects, the primary side circuit includes a capacitive element connected in series with the primary winding of the transformer. The same operation as that of the inventions of items 10 to 13 is achieved.

According to a fifteenth aspect of the present invention, in the invention according to any one of the sixth or seventh aspects and the tenth to fourteenth aspects, the secondary side circuit includes a rectifying element connected in series with the secondary winding of the transformer. The rectifying element is characterized in that the rectifying element is connected in a direction in which a current due to an induced electromotive force induced in a secondary winding of the transformer flows into the photovoltaic element when the photovoltaic element generates the electromotive force. Even when the induced electromotive force is no longer induced in the secondary winding of the transformer, it is possible to prevent the current due to the photovoltaic power from flowing in the secondary winding. Can handle.

According to a sixteenth aspect of the present invention, in the fifteenth aspect of the invention, a switching element that is turned off when the light emitting element of the primary side circuit is turned on and is turned on when the light emitting element is turned off is connected in parallel with the rectifying element. In addition to the action of the invention of claim 15, the switch element is turned on to short-circuit both ends of the rectifying element when the light emitting element is turned off, thereby facilitating discharge of the accumulated charge of the photovoltaic element and the semiconductor switch element. The switching time at turn-off can be shortened.

According to a seventeenth aspect of the present invention, in the sixteenth aspect of the present invention, the switch element is constituted by a MOSFET and the rectifying element is replaced by a parasitic diode of the MOSFET.
The gate electrode of the switching element is connected to one end of the secondary winding, and the same operation as the invention of claim 16 is achieved.

According to an eighteenth aspect of the invention, in the fifteenth aspect of the invention, a switching element which is turned off when the light emitting element of the primary side circuit is turned on and is turned on when the light emitting element is turned off is connected in parallel with the photovoltaic element. In addition to the action of the invention of claim 15, the switching time at turn-off of the semiconductor switch element can be shortened by discharging the accumulated charge of the photovoltaic element through the switch element when the light emitting element is turned off. .

According to a nineteenth aspect of the present invention, in the eighteenth aspect of the present invention, the drain electrode and the source electrode of the switch element formed of the MOSFET are connected to both electrodes of the photovoltaic element, and the auxiliary winding is provided on the secondary side of the transformer. The gate electrode of the switch element is connected to the wire, and the switch element is turned on when an induced electromotive force having a polarity opposite to that of the photoelectromotive force is induced in the secondary winding of the transformer. The same operation as the invention is achieved.

According to a twentieth aspect of the invention, in the first aspect of the invention, the power supply means supplies power to the secondary side circuit in response to a change in the drive voltage applied from the drive power source to the primary side circuit. In addition, it is characterized by comprising electrostatic coupling means for electrostatically coupling the primary side circuit and the secondary side circuit, and shortening the switching time of the semiconductor switch element by supplementing the power transfer by optical coupling by the electrostatic coupling means. It is possible to realize a drive circuit capable of

According to a twenty-first aspect of the invention, in the twentieth aspect of the invention, the primary side circuit is composed of a series circuit of a light emitting element and a resistor which emit light by application of a drive voltage, and the secondary side circuit is optically coupled to the light emitting element. And a voltage having the same polarity as the photovoltaic generated in the photovoltaic element when power is supplied from the driving power source, is applied to the secondary side circuit via an electrostatic coupling means including a capacitor. The primary side circuit and the secondary side circuit are connected to each other, and the same operation as the invention of claim 20 is achieved.

In order to achieve the above-mentioned object, the invention of claim 22 is constituted by connecting the control terminals of two field effect transistors and one main terminal of each pair of main terminals in common. A semiconductor switch element, and the drive circuit according to any one of claims 1 to 21 for providing a control input between a commonly connected control terminal and one of the main terminals. A semiconductor relay capable of shortening the switching time can be realized by supplementing the transmission with the power supply means.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following embodiments, an n-channel MOFFET is exemplified as a semiconductor switch element driven by the drive circuit according to the present invention, but not limited to this, a p-channel MOSFET or an IGBT (insulated gate bipolar transistor). The technical idea of the present invention can be applied to a drive circuit for all semiconductor switch elements including the above. In each embodiment, the magnetic coupling means or the electrostatic coupling means is illustrated as the power supply means, but the invention is not limited to these, and high-speed power transmission such as thermal coupling means or piezoelectric coupling means is possible. Any means can be applied to the power supply means in the present invention.

(Embodiment 1) In this embodiment, as shown in FIG. 1, a drive circuit for a semiconductor switch element 22 composed of one n-channel MOSFET is illustrated. In this embodiment, the gate terminal (hereinafter abbreviated as gate) of the n-channel MOSFET is a control terminal, the source terminal (hereinafter abbreviated as source) is one main terminal, and the drain terminal (hereinafter abbreviated as drain). ) Respectively configure the other main terminals, and the gate voltage (gate-source voltage) applied between the gate and the source serves as the control input.

The drive circuit of the present embodiment is a transformer T 1
Next winding N1, light emitting element 11, resistor R1 and driving power supply 1
The primary side circuit 10 is composed of two series circuits, and the secondary side circuit 20 is composed of a secondary circuit N2 of the transformer T and a series circuit of the photovoltaic element 21 and a control circuit 30. Here, the control circuit 30 is the same as the circuit including the normally-on type n-channel MOSFET 23, the bias resistor R2, and the n-channel MOSFET 24 in the conventional example shown in FIG.

In the primary side circuit 10, a series circuit of the primary winding N1 of the transformer T and the light emitting element 11 is connected between both ends of the driving power source 12 via a resistor R1. The drive power source 12 is composed of a unipolar pulse power source that outputs a pulse voltage suitable for driving the gate of the semiconductor switch element 22, and its output voltage is equal to the ON voltage of the semiconductor switch element (n-channel MOSFET) 22 and 0V. It is possible to take two values.

Further, in the secondary side circuit 20, a series circuit of the secondary winding N2 of the transformer T and the photovoltaic element 21 is connected between the gate and the source of the semiconductor switching element 22. Here, the polarities of the photovoltaic power generated in the photovoltaic element 21 and the induced electromotive force induced in the secondary winding N2 of the transformer T when power is supplied from the driving power supply 12 (when the output voltage is an on-voltage). The polarity of the transformer T is set so that

Next, the operation of the drive circuit of this embodiment will be described.

First, the operation of turning on the semiconductor switch element 22 from the off state to the on state will be described.

When a pulse voltage is output from the driving power source 12 and the output voltage rises from 0V to the ON voltage, the resistor R1
And the light emitting element 11 via the primary winding N1 of the transformer T.
A current flows through the light emitting element 11 to emit light, and a photoelectromotive force is generated in the photovoltaic element 21 optically coupled to the light emitting element 11. On the other hand, when the output voltage of the driving power supply 12 rises, a current rapidly flows in the primary winding N1 of the transformer T, so that an induced electromotive force is generated in the secondary winding N2. Since the polarity of the induced electromotive force generated in the secondary winding N2 is matched with the polarity of the photovoltaic generated in the photovoltaic element 21, these two types of electromotive force (photoelectromotive force and induced electromotive force) The current flowing in the secondary side circuit 20 charges the capacity between the positive electrode and the negative electrode of the photovoltaic element 21 (hereinafter referred to as inter-terminal capacity) and the gate-source capacity (input capacity) of the semiconductor switching element 22. . When the charging voltage exceeds the threshold voltage, the semiconductor switch element 22 turns on.

That is, not only the photovoltaic force generated in the photovoltaic element 21, but also the induced electromotive force generated in the secondary winding N2 of the transformer T is combined with the inter-terminal capacitance of the photovoltaic element 21 and the input of the semiconductor switch element 22. Because the capacity is charged,
It is possible to shorten the time required to turn on the semiconductor switch element 22 (switching time), as compared with the conventional example using only photovoltaic power.

Next, the operation when the semiconductor switch element 22 is turned off from the on state to the off state will be described.

When the output voltage of the driving power source 12 becomes 0V and the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases, and the control circuit 30 causes the semiconductor switching element 2 to operate.
2 the electric charge accumulated between the gate and the source and the electric charge accumulated between the positive electrode and the negative electrode of the photovoltaic element 21 are discharged, and the gate-source voltage of the semiconductor switching element 22 falls below the threshold voltage. When this happens, the semiconductor switch element 22 is turned off. Here, when the output voltage of the driving power supply 12 falls from the on-voltage to 0 V, the voltage of the transformer T becomes 1
When the current flowing through the secondary winding N1 suddenly decreases, an induced electromotive force is generated in the secondary winding N2 in the direction of reverse biasing between the gate and the source of the semiconductor switch element 22, and the control circuit 30
The discharge of the electric charge by is promoted.

At the time of turn-off, the induced electromotive force generated in the secondary winding N2 of the transformer T reversely biases the gate and source of the semiconductor switch element 22 so that the semiconductor switch is different from the conventional example. It is possible to shorten the time required to turn off the element 22 (switching time).

(Embodiment 2) In this embodiment, as shown in FIG. 2, a diode 13 is connected in antiparallel with a light emitting element 11 of a primary side circuit 10, and a drive power source 12 outputs positive and negative pulse voltages. It is characterized in that it is composed of a bipolar pulsed power supply, and other configurations and operations at turn-on are the same as in the first embodiment.

Next, the operation at turn-off, which is a feature of this embodiment, will be described.

The output voltage of the driving power supply 12 is 0 from the on-voltage.
When the voltage exceeds V and decreases to an off voltage (for example, a voltage obtained by reversing the polarity of an on voltage), the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases, and the primary winding of the transformer T decreases. The current flowing through N1 is rapidly inverted, and an induced electromotive force is generated in the secondary winding N2 in the direction in which the gate and source of the semiconductor switch element 22 are reversely biased. Since the induced electromotive force at this time is considerably larger than the induced electromotive force generated when the output voltage of the drive power supply 12 falls in the first embodiment, the discharge of electric charges is further promoted as compared with the first embodiment, and the semiconductor switch element 22. This will further reduce the time required to turn off the.

(Embodiment 3) In this embodiment, as shown in FIG. 3, the primary side circuit 10 includes a series circuit of a light emitting element 11 and a resistor R3 and a series circuit of a primary winding N1 and a resistor R1 of a transformer T. It is characterized by being connected in parallel with each other,
Other configurations and operations are basically the same as those of the second embodiment.

In the present embodiment, when the output voltage of the driving power supply 12 rises to the on-voltage, the light emitting element 1 passes through the resistor R3.
When a current flows through the resistor 1, the current also flows through the primary winding N1 of the transformer T via the resistor R1 to turn on the semiconductor switch element 22, and the output voltage of the driving power supply 12 falls from the on voltage to the off voltage. A current flows in the reverse direction only through the primary winding N1 of the transformer T via the resistor R1 to turn off the semiconductor switch element 22.

Thus, in this embodiment, the current flowing through the light emitting element 11 is adjusted by the resistor R3 connected in series with the light emitting element 11, and the primary winding is adjusted by the resistor R1 connected in series with the primary winding N1. By adjusting the current flowing through N1, there is an advantage that power transfer by optical coupling and power transfer by electromagnetic coupling can be individually designed.

(Embodiment 4) FIG. 4 is a circuit diagram of this embodiment.
Shown in. However, since the basic configuration is the same as that of the second embodiment, the common components are designated by the same reference numerals and the description thereof will be omitted.

In the primary side circuit 10, a series circuit of a primary winding N1 of a transformer T, a light emitting element 11 and a resistor R1 is connected between both ends of a driving power source 12, and a diode 13 and a resistor R1 are connected.
The series circuit of 3 and the capacitor C1 are connected in parallel with the series circuit of the light emitting element 11 and the resistor R1. The diode 13 is antiparallel to the light emitting element 11, that is, the cathode of the diode 13 is connected to the anode of the light emitting element 11, and the cathode of the light emitting element 11 and the anode of the diode 13 are connected via resistors R1 and R3.

In the secondary side circuit 20, the series circuit of the secondary winding N2 of the transformer T and the diode 25 is connected in parallel with the photovoltaic element 21, and the switching element 26 composed of a normally-off type n-channel MOSFET is provided. It is connected in parallel with the diode 25. The diode 25 is replaced by a parasitic diode of the switch element 26 (n-channel MOSFET). Here, the diode 25 is connected in a direction in which it is made conductive by the induced electromotive force induced in the secondary winding N2 of the transformer T when the output voltage of the drive power supply 12 rises from the off voltage to the on voltage. The drain and source of the switch element 26 are connected to the cathode and anode of the diode 25, respectively, and the gate is connected to the negative electrode of the photovoltaic element 21.

Next, the operation of the drive circuit of this embodiment will be described.

First, the operation of turning on the semiconductor switch element 22 from the off state to the on state will be described.

When a pulse voltage is output from the driving power supply 12 and the output voltage rises to an on-voltage, a current flows through the light emitting element 11 via the primary winding N1 of the transformer T, and the light emitting element 11 emits light, and the light emitting element is emitted. Photovoltaic is generated in the photovoltaic element 21 optically coupled to 11. On the other hand, when the output voltage of the driving power supply 12 rises, the primary winding N1 of the transformer T
The induced electromotive force is generated in the secondary winding N2 due to the rapid current flow in the coil. Since the polarity of the induced electromotive force generated in the secondary winding N2 is matched with the polarity of the photovoltaic generated in the photovoltaic element 21, these two types of electromotive force (photoelectromotive force and induced electromotive force) The inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switching element 22 are charged by the current flowing in the secondary circuit 20. When the charging voltage exceeds the threshold voltage, the semiconductor switch element 22 turns on.

Here, at the initial point in time when the output voltage of the driving power supply 12 rises, the impedance of the capacitor C1 is lower than the impedance of the series circuit of the light emitting element 11 and the resistor R1. As compared with the case where the capacitor C1 is not provided, a large current flows rapidly in the primary winding N1 of the transformer T. Therefore, the induced electromotive force induced in the secondary winding N2 is larger than that in the case where the capacitor C1 is not provided, and the time required to charge the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switch element 22, that is, The time for turning on the semiconductor switch element 22 can be further shortened. The timing at which the induced electromotive force of the secondary winding N2 fully charges the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switching element 22, that is, the semiconductor switching element 22 is constantly turned on. If the capacitor C1 is designed to be fully charged in a state where the capacitor C1 is fully charged, all the current in the primary side circuit 10 flows through the light emitting element 11 and the resistor R1 after the capacitor C1 is fully charged, so that the current is reduced and the steady state is maintained. It is possible to suppress power consumption in the.
Moreover, the current flowing through the light emitting element 11 is 1
It is possible to adjust the current flowing through the next winding N1 independently of the current flowing at the initial time so that a required amount can flow in a steady state according to the resistance value of the resistor R1, and it is not necessary to flow a large current through the light emitting element 11. Therefore, the operation of the entire drive circuit can be stabilized by extending the element life of the light emitting element 11 or suppressing the heat generation.

On the other hand, in the secondary side circuit 20, the secondary winding N2 of the transformer T is higher than the photovoltaic power of the photovoltaic element 21.
The rise of the induced electromotive force is faster than that of the drive power source 12. Therefore, at the initial stage (transition time) of the rise of the output voltage of the drive power source 12, a current is mainly supplied through the diode 25 by the induced electromotive force of the secondary winding N2. Then, the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switch element 22 are charged. In the subsequent steady state, the induced electromotive force of the secondary winding N2 disappears, but the diode 25 causes the charge between the terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switch element 22 to pass through the secondary winding N2. After the photoelectromotive force of the photovoltaic element 21 is completely raised, the charge between the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switching element 22 is charged by the photoelectromotive force. Will be held by.

That is, similarly to the first to third embodiments, this embodiment can shorten the switching time when the semiconductor switch element 22 is turned on, as compared with the conventional example using only the photovoltaic power. Further, in the present embodiment, as described above, the input power to the primary side circuit 10 in the steady state after turning on the semiconductor switch element 22 can be reduced, the life of the light emitting element 11 can be extended, and the drive circuit can be reduced. There is an advantage that the whole operation can be stabilized.

Next, the operation when the semiconductor switch element 22 is turned off from the on state to the off state will be described.

When the output voltage of the driving power source 12 exceeds 0V and decreases to the off voltage, the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases, and the current flowing through the primary winding N1 of the transformer T decreases. Secondary winding N2
An induced electromotive force having a polarity opposite to that of the photoelectromotive force at turn-on is induced in. The induced electromotive force causes forward bias between the gate and the source of the switch element 26, and
Turns on and short-circuits the anode and cathode of the diode 25. As a result, the charge between the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switch element 22 is rapidly discharged by the induced electromotive force via the switch element 26. At this time, the current flowing through the primary winding N1 of the transformer T is at the initial stage of the fall of the output voltage of the driving power supply 12,
As in the case of the above-mentioned turn-on (when the output voltage rises), it rapidly flows through the capacitor C1 and flows in the steady state through the diode 13 and the resistor R3. And at the same time, the input power of the primary circuit 10 in the steady state can be reduced.

(Embodiment 5) FIG. 5 is a circuit diagram of this embodiment.
Shown in. However, since the basic configuration is the same as that of the fourth embodiment, the common components are designated by the same reference numerals and the description thereof will be omitted.

In the primary side circuit 10, the delay section 16, the series circuit of the primary winding N1 of the transformer T, the capacitor C1, and the resistor R2 and the series circuit of the light emitting element 11 and the resistor R1 are connected between both ends of the drive power source 12. Are connected in parallel to each other, and the resistor R4 is connected in parallel to the capacitor C1.

The delay unit 16 includes two inverters IV1 and IV1.
It is composed of a series circuit of IV2 and delays the rise and fall of the output voltage applied from the drive power supply 12 to the primary winding N1 of the transformer T. That is, in the present embodiment, a control unit that controls (delays) the timing at which the induced electromotive force is induced in the secondary winding N2 of the transformer T so as not to be earlier than the timing at which the photovoltaic electromotive force is generated in the photovoltaic element 21. Is constituted by the delay unit 16. The configuration of the secondary circuit 20 is the same as that of the fourth embodiment.

Next, the operation of the drive circuit of this embodiment will be described.

First, the operation of turning on the semiconductor switch element 22 from the off state to the on state will be described.

When a pulse voltage is output from the driving power supply 12 and the output voltage rises to an ON voltage, a current flows through the light emitting element 11 to cause the light emitting element 11 to emit light, and the photovoltaic element optically coupled to the light emitting element 11. In addition to the generation of a photoelectromotive force in the transformer 21, an abrupt current flow in the primary winding N1 of the transformer T causes an induced electromotive force in the secondary winding N2. These two types of electromotive force (photoelectromotive force and induced electromotive force) are generated. (Electric power) charges the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switching element 22 with a current flowing in the secondary circuit 20, and when the charging voltage exceeds a threshold voltage, the semiconductor switching element 22 turns on.

By the way, the light emitting element 11 and the transformer T 1
If the ON voltage is applied to the secondary winding N1 at the same timing, the timing of generating the photovoltaic power of the photovoltaic element 21 is delayed from the timing of generating the induced electromotive force in the secondary winding N2 of the transformer T, The charged charges of the inter-terminal capacitance of the photovoltaic element 21 charged by the induced electromotive force will be discharged through the photovoltaic element 21 itself in which no photovoltaic is generated. On the other hand, in this embodiment, the rising of the voltage applied to the primary winding N1 of the transformer T is delayed by the delay unit 16, and the photovoltaic device 2
The timing at which the photoelectromotive force is generated at 1 is not later than the timing at which the induced electromotive force is induced in the secondary winding N2 of the transformer T, thereby preventing the discharge of electric charges due to the above-described delay in the generation of the photoelectromotive force. . Further, the series circuit of the capacitor C1 and the resistor R2 forms a differentiating circuit, and the driving power source 1
Since the voltage applied to the primary winding N1 of the transformer T from 2 becomes steep and the falling thereof becomes relatively gradual, the secondary voltage is applied when the voltage applied to the primary winding N1 of the transformer T falls. It is possible to suppress the induced electromotive force having a polarity opposite to that of the photoelectromotive force induced in the winding N2 and suppress the voltage fluctuation of the secondary side circuit 20 in the steady state. Further, the resistor R4 connected in parallel to the capacitor C1 consumes the energy stored in the primary winding N1 to quickly converge the series resonance by the primary winding N1, the capacitor C1 and the resistor R2, and consumes the power in a steady state. The current is controlled by the resistor R4. Note that the operation of the secondary circuit 20 is the same as that of the fourth embodiment, so a description thereof will be omitted.

That is, similarly to the first to fourth embodiments, this embodiment can shorten the switching time when the semiconductor switch element 22 is turned on, as compared with the conventional example using only the photovoltaic power. Further, in the present embodiment, as described above, the timing at which the photovoltaic power is generated in the photovoltaic element 21 is not delayed from the timing at which the induced electromotive force is induced in the secondary winding N2 of the transformer T. The semiconductor switch element 22 can be surely turned on by preventing the discharge of charges due to the delay of the generation of photovoltaic power, and the input to the primary side circuit 10 in the steady state after the semiconductor switch element 22 is turned on. There is an advantage that the power can be reduced, the life of the light emitting element 11 can be extended, and the operation of the entire drive circuit can be stabilized.

Next, the operation of turning off the semiconductor switch element 22 from the on state to the off state will be described.

When the output voltage of the driving power source 12 exceeds 0V and decreases to the off voltage, the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases, and the current flowing through the primary winding N1 of the transformer T. Secondary winding N2
An induced electromotive force having a polarity opposite to that of the photoelectromotive force at turn-on is induced in. The induced electromotive force causes forward bias between the gate and the source of the switch element 26, and
Is turned on to short-circuit the anode-cathode of the diode 25, and the charge between the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switching element 22 becomes the switching element 2.
It is rapidly discharged by the induced electromotive force via 6. At this time, if the timing at which the light emitting element 11 is turned off and the timing at which the off voltage is applied to the primary winding N1 of the transformer T are the same, the induced electromotive force generated in the secondary winding N2 of the transformer T causes the photovoltaic power. Since the discharge of the charging charge of the inter-terminal capacitance of the element 21 and the input capacitance of the semiconductor switching element 22 is hindered, in the present embodiment, the primary winding N1 of the transformer T.
The fall of the voltage applied to the delay element 16 is delayed by the delay unit 16, and the timing at which the photovoltaic power of the photovoltaic element 21 disappears is later than the timing at which the induced electromotive force is induced in the secondary winding N2 of the transformer T. Therefore, the discharge delay of the electric charges due to the above-mentioned delay of the disappearance of the photovoltaic power is prevented. Further, the current flowing through the primary winding N1 of the transformer T rapidly flows through the capacitor C1 at the initial stage of the fall of the output voltage of the driving power supply 12, similarly to the above-mentioned turn-on (at the rise of the output voltage), Resistance R in steady state
As described above, the switching time at turn-off can be shortened as well as at turn-on, and at the same time, the input power of the primary side circuit 10 at the steady state can be reduced.

That is, in the present embodiment, as described above,
Since the timing at which the photovoltaic power of the photovoltaic element 21 is extinguished is not later than the timing at which the induced electromotive force of the opposite polarity is induced in the secondary winding N2 of the transformer T, the delay of the photovoltaic power extinction is delayed. The semiconductor switch element 22 can be surely turned off by preventing the electric charge from being discharged by the electric discharge, and the input power to the primary side circuit 10 in the steady state after the semiconductor switch element 22 is turned off can be reduced. .

The secondary side circuit 20 of this embodiment is shown in FIG.
The circuit configuration shown in FIG. That is, the two ends of the secondary winding N2 of the transformer T are respectively connected to the switching elements 26a, 2a.
6b is connected to both electrodes of the photovoltaic element 21, and the gates of the switch elements 26a and 26b are connected to one end of the secondary winding N2 connected to the other switch elements 26b and 26a, respectively. . In addition, diodes 25a and 25b, which are parasitic diodes, are connected in parallel to the switch elements 26a and 26b. When the semiconductor switch element 22 is turned on, the switch element 26a is turned on by the induced electromotive force induced in the secondary winding N2,
At the time of turn-off, the switch element 26b is turned on by the induced electromotive force of the opposite polarity induced in the secondary winding N2,
Terminal capacitance of photovoltaic element 21 and semiconductor switching element 2
Charging / discharging to the input capacity of 2 is performed.

(Embodiment 6) FIG. 7 is a circuit diagram of this embodiment.
Shown in. However, since the basic configuration is the same as that of the fifth embodiment, the common components are designated by the same reference numerals and the description thereof will be omitted.

In the secondary side circuit 20, the series circuit of the secondary winding N2 of the transformer T and the diode 25 and the switch element 2 consisting of a normally-off type n-channel MOSFET.
6 is connected in parallel with the photovoltaic element 21, and the transformer T
Both ends of the auxiliary winding N3 provided on the secondary side of are connected to the gate of the switch element 26 and the negative electrode of the photovoltaic element 21, respectively. The auxiliary winding N3 is set to have the same polarity as the secondary winding N2, and when an induced electromotive force having the same polarity as the photoelectromotive force is generated in the secondary winding N2, the switch element 26 is reverse-biased and the secondary An induced electromotive force that forward biases the switch element 26 is induced when an induced electromotive force having a polarity opposite to that of the photovoltaic electromotive force is generated in the winding N2. Since the configuration of the primary side circuit 10 is the same as that of the fifth embodiment, the description is omitted.

Next, the operation of the drive circuit of this embodiment will be described. However, the operation when turning on the semiconductor switch element 22 from the off state to the on state is the same as that of the fifth embodiment, and therefore its explanation is omitted, and only the operation when turning off the semiconductor switch element 22 from the on state to the off state is performed. explain.

When the output voltage of the driving power source 12 exceeds 0V and decreases to the off voltage, the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases, and the current flowing through the primary winding N1 of the transformer T decreases. Secondary winding N2
Further, induced electromotive force having a polarity opposite to that of the photoelectromotive force at turn-on is induced in the auxiliary winding N3. The induced electromotive force forward-biases the gate and source of the switch element 26 to turn on the switch element 26, short-circuit both electrodes of the photovoltaic element 21 and the gate and source of the semiconductor switch element 22, and thereby generate the photovoltaic force. When the charge between the terminal capacitance of the element 21 and the input capacitance of the semiconductor switch element 22 is rapidly discharged through the switch element 26 and the gate-source voltage of the semiconductor switch element 22 falls below the threshold voltage, the semiconductor switch element. 22 turns off.

At the time of turn-off, the switch element 26 is turned on by the induced electromotive force generated in the auxiliary winding N3 of the transformer T, and the gate-source of the semiconductor switch element 22 is reverse biased via the switch element 26. By doing so, it is possible to shorten the time (switching time) required to turn off the semiconductor switch element 22 as compared with the conventional example.

(Embodiment 7) The drive circuit of this embodiment is
As shown in FIG. 8, a primary side circuit 10 including a series circuit of a light emitting element 11, a resistor R1, and a driving power source 12 including a bipolar pulse power source that outputs positive and negative pulse voltages, a photovoltaic element 21, and a control circuit. Secondary side circuit 20 consisting of 30
And the primary side circuit 10 and the secondary side circuit 20 are electrostatically coupled so as to supply power to the secondary side circuit 20 in accordance with a change in the drive voltage applied from the drive power source 12 to the primary side circuit 10. And electrostatic coupling means. Here, the electrostatic coupling means is
The capacitor 14 connected between the connection point of the driving power source 12 and the resistor R1 and the positive electrode of the photovoltaic element 21, and the driving power source 1
2 and a capacitor 15 connected between the negative electrode of the light emitting element 11 and the negative electrode of the photovoltaic element 21.

Next, the operation of the drive circuit of this embodiment will be described.

First, the operation of turning on the semiconductor switch element 22 from the off state to the on state will be described.

When a pulse voltage is output from the driving power supply 12 and the output voltage rises from an off voltage to an on voltage, a current flows through the light emitting element 11 through the resistor R1 and the primary winding N1 of the transformer T, and the light emitting element 11 Emits light, and light-emitting element 1
1 is photo-coupled to the photovoltaic element 21 to cause a current to flow in the secondary side circuit 20, and at the rising of the output voltage of the driving power source 12, the capacitors 14, 1
A current is supplied from the drive power source 12 to the secondary side circuit 20 via 5, and the inter-terminal capacitance of the photovoltaic element 21 and the input capacitance of the semiconductor switching element 22 are charged. When the charging voltage exceeds the threshold voltage, the semiconductor switch element 22 turns on.

That is, not only the current due to the photovoltaic power generated in the photovoltaic element 21, but also the current supplied from the driving power source 12 via the capacitors 14 and 15 together with the inter-terminal capacitance of the photovoltaic element 21 and the semiconductor switch. Since the input capacitance of the element 22 is charged, the switching time required to turn on the semiconductor switching element 22 can be shortened as compared with the conventional example using only the photovoltaic power.

Next, the operation of turning off the semiconductor switch element 22 from the on state to the off state will be described.

When the output voltage of the driving power supply 12 falls from the on-voltage to the off-voltage and the light emitting element 11 is turned off, the output current of the photovoltaic element 21 decreases, and the control circuit 30 causes the gate-source of the semiconductor switching element 22. The semiconductor switch when the charge accumulated between them and the charge accumulated between the positive electrode and the negative electrode of the photovoltaic element 21 are discharged and the gate-source voltage of the semiconductor switching element 22 falls below the threshold voltage. Element 22 turns off. Here, when the output voltage of the drive power supply 12 falls to the off voltage, a current is supplied from the drive power supply 12 to the secondary side circuit 20 via the capacitors 14 and 15 to accelerate the discharge of electric charges by the control circuit 30. It will be.

At the time of turn-off, the gate-source of the semiconductor switch element 22 is reversely biased by the driving power supply 12 via the capacitors 14 and 15, so that the semiconductor switch element 22 is turned off as compared with the conventional example. It is possible to shorten the switching time required for this.

(Embodiment 8) In this embodiment, as shown in FIG. 9, a semiconductor switch element 22 composed of two n-channel MOSFETs 22a and 22b whose gates and sources are commonly connected to each other, and a semiconductor switch element of Embodiment 3 are provided. It constitutes a semiconductor relay called a so-called photo-MOS relay, which is provided with a drive circuit. However, since the operation of turning on and off the semiconductor switch element 22 is the same as that of the third embodiment, the description thereof will be omitted.

Thus, also in the semiconductor relay configured as described above, the switching time can be shortened as compared with the conventional semiconductor relay. The drive circuit forming the semiconductor relay is not limited to that of the third embodiment, and may be any of the drive circuits of the first, second and fourth to seventh embodiments.

[0092]

According to the first aspect of the present invention, the primary side circuit and the secondary side circuit optically coupled to each other are provided, and the power is transmitted from the driving power source to the secondary side circuit through the primary side circuit through the light as a medium. Then
In the drive circuit for switching the semiconductor switch element by the secondary side circuit using the transmitted electric power, the electric power for supplying the input electric power to the primary side circuit to the secondary side circuit separately from the electric power transmission using light as a medium. Since the power supply means is provided, there is an effect that a drive circuit capable of shortening the switching time of the semiconductor switch element can be realized by supplementing the power transmission by optical coupling with the power supply means.

According to a second aspect of the present invention, in the first aspect of the invention, the power supply means supplies power to the secondary side circuit in response to a change in the drive voltage applied from the drive power source to the primary side circuit. Since the primary side circuit and the secondary side circuit are electromagnetically coupled to each other by electromagnetic coupling means, a driving circuit capable of shortening the switching time of the semiconductor switch element by supplementing the power transmission by optical coupling by the electromagnetic coupling means is provided. There is an effect that it can be realized.

According to the invention of claim 3, in the invention of claim 2, since the electromagnetic coupling means comprises a transformer, the same effect as that of the invention of claim 2 can be obtained.

According to a fourth aspect of the present invention, in the third aspect of the invention, the primary side circuit is composed of a series circuit of a primary winding of a transformer and a light emitting element which emits light when a drive voltage is applied, and the secondary side circuit. Is composed of a series circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element, and the photovoltaic generated in the photovoltaic element when power is supplied from a driving power source and the secondary winding of the transformer Since the polarity of the induced electromotive force is matched with that of the induced electromotive force, in addition to the effect of the invention of claim 3, the timing of power transfer by optical coupling and the timing of power transfer by magnetic coupling naturally match and control becomes easy. There is an effect.

According to a fifth aspect of the present invention, in the third aspect of the invention, the primary side circuit is configured by connecting in parallel the light emitting element that emits light by the application of a drive voltage and the primary winding of the transformer, and the secondary side. The circuit is composed of a series circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element, and the photovoltaic generated in the photovoltaic element when power is supplied from a drive power source and the secondary winding of the transformer Since the polarity of the induced electromotive force induced in the transformer is matched, the current flowing in the light emitting element and the current flowing in the primary winding of the transformer can be individually adjusted in addition to the effect of the invention of claim 3. Therefore, there is an effect that power transmission by optical coupling and power transmission by electromagnetic coupling can be independently designed individually.

According to a sixth aspect of the present invention, in the third aspect of the invention, the primary side circuit is composed of a series circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and the secondary side circuit. Is composed of a parallel circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element. The photovoltaic generated in the photovoltaic element when power is supplied from a driving power source and the secondary winding of the transformer Since the polarity of the induced electromotive force is the same as that of the induced electromotive force, the same effect as that of the invention of claim 3 is obtained.

According to a seventh aspect of the invention, in the third aspect of the invention, the primary side circuit is composed of a parallel circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and the secondary side circuit. Is composed of a parallel circuit of a secondary winding of a transformer and a photovoltaic element optically coupled to a light emitting element. The photovoltaic generated in the photovoltaic element when power is supplied from a driving power source and the secondary winding of the transformer Since the polarities of the induced electromotive force and the induced electromotive force are matched, the current flowing through the light emitting element and the current flowing through the primary winding of the transformer can be individually adjusted in addition to the effect of the invention of claim 3. There is an effect that power transmission by optical coupling and power transmission by electromagnetic coupling can be independently designed.

According to the invention of claim 8 in the invention of claim 4 or 6, since the primary side circuit includes a rectifying element connected in antiparallel with the light emitting element, the effect of the invention of claim 4 or 6 is achieved. In addition, when the semiconductor switch element is turned off, a reverse current is caused to flow through the primary winding of the transformer via the rectifying element to induce an induced electromotive force in the secondary winding of the transformer in the opposite direction to that at the time of turn-on. Therefore, there is an effect that the switching time when the semiconductor switch element is turned off can be shortened.

The invention of claim 9 is the invention of claim 4 or 6 or 8.
In the invention of claim 1, since the primary side circuit includes a capacitive element connected in parallel with the light emitting element, a large current flows through the primary winding of the transformer through the capacitive element having a low impedance at the rise of the drive voltage. It is possible to induce a large induced electromotive force in the secondary winding, and there is an effect that the switching time can be further shortened. Further, after the drive voltage rises and becomes stable, almost no current flows through the capacitive element, which has the effect of reducing power consumption in the primary side circuit.

According to a tenth aspect of the present invention, in the fifth or seventh aspect of the present invention, the timing at which the induced electromotive force is induced in the secondary winding of the transformer is not earlier than the timing at which the photovoltaic element generates the photovoltaic force. Since the control means for controlling is provided, the charging charge of the photovoltaic element is not discharged by the induced electromotive force induced in the secondary winding of the transformer, and the switching time can be further shortened. There is.

According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, there is provided means for shortening the time for which the induced electromotive force is induced in the secondary winding of the transformer to be shorter than the time for the photovoltaic element to generate the photoelectromotive force. Since it is provided, in addition to the effect of the invention of claim 10, there is an effect that the power consumption in the primary side circuit can be reduced.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, there is provided means for making the rise of the drive voltage applied to the primary winding of the transformer from the drive power source sharp and the fall relatively gentle. Therefore, in addition to the effect of the invention of claim 11, the induced electromotive force having a polarity opposite to that of the photoelectromotive force induced in the secondary winding when the drive voltage applied to the primary winding of the transformer falls is suppressed. Therefore, there is an effect that the voltage fluctuation of the secondary side circuit in the steady state can be suppressed.

According to a thirteenth aspect of the present invention, in the twelfth aspect of the invention, the transformer 2 is turned off when the power supply from the drive power source is stopped.
The induced electromotive force induced in the next winding has a polarity opposite to that of the photovoltaic power generated in the photovoltaic element when power is supplied from the driving power source. Therefore, in addition to the effect of the invention of claim 12, There is an effect that the discharge time of the charge accumulated in the gate electrode and the charge accumulated in the photovoltaic element can be promoted to shorten the switching time when the semiconductor switch element is turned off.

According to a fourteenth aspect of the present invention, in any one of the tenth to thirteenth aspects, the primary side circuit includes a capacitive element connected in series with the primary winding of the transformer. The same effect as that of the thirteenth invention is achieved.

According to a fifteenth aspect of the present invention, in any one of the sixth or seventh aspect and the tenth to fourteenth aspects, the secondary side circuit includes a rectifying element connected in series with the secondary winding of the transformer. , The rectifying element is connected so that the current due to the induced electromotive force induced in the secondary winding of the transformer flows into the photovoltaic element when the photovoltaic element generates the photovoltaic element. It is possible to prevent the current due to the photovoltaic power from flowing to the secondary winding after the induced electromotive force is no longer induced in the secondary winding, and it can be used even when it is necessary to maintain the power of the secondary side circuit for a long time. effective.

According to the sixteenth aspect of the invention, in the fifteenth aspect of the invention, the switch element which is turned off when the light emitting element of the primary side circuit is turned on and is turned on when the light emitting element is turned off is connected in parallel with the rectifying element. In addition to the effect of the invention as set forth in claim 15, when the light emitting element is turned off, the switch element is turned on and short-circuits both ends of the rectifying element. Therefore, discharge of accumulated charges of the photovoltaic element is promoted to turn off the semiconductor switch element. The switching time can be shortened.

According to a seventeenth aspect of the invention, in the sixteenth aspect of the invention, the switch element is constituted by a MOSFET and the rectifying element is replaced by a parasitic diode of the MOSFET.
Since the gate electrode of the switch element is connected to one end of the secondary winding, the same effect as the invention of claim 16 is obtained.

According to an eighteenth aspect of the invention, in the fifteenth aspect of the invention, a switching element which is turned off when the light emitting element of the primary side circuit is turned on and is turned on when the light emitting element is turned off is connected in parallel with the photovoltaic element. Therefore, in addition to the effect of the fifteenth aspect of the invention, there is an effect that the switching time at turn-off of the semiconductor switch element can be shortened by discharging the accumulated charge of the photovoltaic element through the switch element when the light emitting element is turned off. is there.

According to a nineteenth aspect of the invention, in the eighteenth aspect of the invention, the drain electrode and the source electrode of the switch element formed of the MOSFET are connected to both electrodes of the photovoltaic element, and an auxiliary winding is provided on the secondary side of the transformer. The gate electrode of the switch element is connected to the wire, and the switch element is turned on when an induced electromotive force having a polarity opposite to that of the photoelectromotive force is induced in the secondary winding of the transformer. Produce the effect of.

According to a twentieth aspect of the invention, in the first aspect of the invention, the power supply means supplies power to the secondary side circuit in response to a change in the drive voltage applied from the drive power source to the primary side circuit. In addition, since the electrostatic coupling means for electrostatically coupling the primary side circuit and the secondary side circuit is used, the switching time of the semiconductor switch element can be shortened by supplementing the electric power transmission by the optical coupling by the electrostatic coupling means. There is an effect that a drive circuit can be realized.

According to a twenty-first aspect of the invention, in the twentieth aspect of the invention, the primary side circuit is composed of a series circuit of a light emitting element and a resistor which emits light when a driving voltage is applied, and the secondary side circuit is optically coupled to the light emitting element. And a voltage having the same polarity as the photovoltaic generated in the photovoltaic element when power is supplied from the driving power source, is applied to the secondary side circuit via an electrostatic coupling means including a capacitor. Since the primary side circuit and the secondary side circuit are connected together, the same effect as the invention of claim 20 is achieved.

In order to achieve the above-mentioned object, the invention of claim 22 is constituted by connecting the control terminals of two field effect transistors and one main terminal of each pair of main terminals in common. The semiconductor switch element and the drive circuit according to any one of claims 1 to 21 for providing a control input between a commonly connected control terminal and one of the main terminals are provided. There is an effect that a semiconductor relay capable of shortening the switching time can be realized by supplementing the supply means.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a circuit diagram showing a second embodiment.

FIG. 3 is a circuit diagram showing a third embodiment.

FIG. 4 is a circuit diagram showing a fourth embodiment.

FIG. 5 is a circuit diagram showing a fifth embodiment.

FIG. 6 is a circuit diagram showing another configuration of the above.

FIG. 7 is a circuit diagram showing a sixth embodiment.

FIG. 8 is a circuit diagram showing a seventh embodiment.

FIG. 9 is a circuit diagram showing an eighth embodiment.

FIG. 10 is a circuit diagram showing a conventional example.

[Explanation of symbols]

10 Primary circuit 11 Light emitting element 12 Drive power supply 20 Secondary circuit 21 Photovoltaic device 22 Semiconductor switch element T transformer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5F089 AB03 AC30 CA12 FA10                 5H740 AA05 BA12 BC01 BC02 KK04                 5J050 AA02 BB18 CC11 DD03 EE02                       EE21 FF04 FF10                 5J055 AX02 BX00 BX16 BX17 DX12                       EX07 EY01 EY07 EY10 EY12                       EY14 EY21 EY28 EZ00 GX01

Claims (22)

[Claims] 1. A primary side circuit and a secondary side circuit optically coupled to each other, wherein electric power is transmitted from a driving power source to the secondary side circuit through the primary side circuit using light as a medium, and the transmitted electric power is transmitted. In the drive circuit for switching the semiconductor switch element by the secondary side circuit using the above, the power supply means for supplying the input power to the primary side circuit to the secondary side circuit is provided separately from the above-mentioned power transmission using light as a medium. A drive circuit for a semiconductor switch element, which is characterized in that: 2. The power supply means electromagnetically connects the primary side circuit and the secondary side circuit to supply power to the secondary side circuit in response to a change in a drive voltage applied from the drive power source to the primary side circuit. 2. The drive circuit for a semiconductor switch element according to claim 1, comprising electromagnetic coupling means for coupling. 3. The drive circuit for a semiconductor switch element according to claim 2, wherein the electromagnetic coupling means comprises a transformer. 4. The primary side circuit is composed of a series circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and the secondary side circuit is a light source for the secondary winding of the transformer and the light emitting element. It is composed of a series circuit with a coupled photovoltaic element, and matches the polarity of the photovoltaic power generated in the photovoltaic element when power is supplied from the driving power source with the induced electromotive force induced in the secondary winding of the transformer. The drive circuit for a semiconductor switch element according to claim 3, wherein 5. A primary side circuit is constituted by connecting a light emitting element that emits light by application of a drive voltage and a primary winding of a transformer in parallel, and a secondary side circuit is a secondary winding of the transformer and a light emitting element. It consists of a series circuit with photovoltaic elements that are optically coupled,
4. The semiconductor switch according to claim 3, wherein the polarities of the photoelectromotive force generated in the photovoltaic element when the power is supplied from the driving power source and the induced electromotive force induced in the secondary winding of the transformer are matched. Device drive circuit. 6. The primary side circuit is composed of a series circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and a secondary side circuit is configured to output light to the secondary winding of the transformer and the light emitting element. It is composed of a parallel circuit with a coupled photovoltaic element, and makes the polarities of the photovoltaic power generated in the photovoltaic element when power is supplied from the drive power source and the induced electromotive force induced in the secondary winding of the transformer match. The drive circuit for a semiconductor switch element according to claim 3, wherein 7. The primary side circuit is composed of a parallel circuit of a primary winding of a transformer and a light emitting element that emits light when a drive voltage is applied, and the secondary side circuit is an optical circuit for the secondary winding of the transformer and the light emitting element. It is composed of a parallel circuit with a coupled photovoltaic element, and makes the polarities of the photovoltaic power generated in the photovoltaic element when power is supplied from the drive power source and the induced electromotive force induced in the secondary winding of the transformer match. The drive circuit for a semiconductor switch element according to claim 3, wherein 8. The drive circuit for a semiconductor switch element according to claim 4, wherein the primary side circuit includes a rectifying element connected in antiparallel with the light emitting element. 9. The primary side circuit comprises a capacitive element connected in parallel with the light emitting element.
Or a drive circuit of the semiconductor switch element according to item 8. 10. A control means for controlling the timing of inducing the induced electromotive force in the secondary winding of the transformer so as not to be earlier than the timing of generating the electromotive force in the photovoltaic element. Item 5. A drive circuit for a semiconductor switch element according to item 5 or 7. 11. A means for reducing the time for which an induced electromotive force is induced in the secondary winding of the transformer to be shorter than the time for which a photovoltaic element produces a photovoltaic force.
A drive circuit for the semiconductor switch element described. 12. The semiconductor switching device according to claim 11, further comprising means for making a rise of the voltage applied from the drive power source to the primary winding of the transformer steep and making the fall relatively gentle. Drive circuit. 13. The induced electromotive force induced in the secondary winding of the transformer when the power supply from the drive power supply is stopped has a polarity opposite to that of the photovoltaic power generated in the photovoltaic element when the power is supplied from the drive power supply. The drive circuit for a semiconductor switch element according to claim 12. 14. The drive circuit for a semiconductor switch element according to claim 10, wherein the primary side circuit includes a capacitive element connected in series with the primary winding of the transformer. 15. The secondary side circuit comprises a rectifying element connected in series with the secondary winding of the transformer, wherein the rectifying element is the secondary winding of the transformer when a photovoltaic element produces a photovoltaic force. 15. The drive circuit for a semiconductor switch element according to claim 6, wherein the current is induced by the induced electromotive force induced in the photovoltaic element so as to flow into the photovoltaic element. . 16. The rectifying element is connected in parallel with a switch element which is turned off when the light emitting element of the primary side circuit is turned on and is turned on when the light emitting element is turned off.
5. The drive circuit for the semiconductor switch element according to 5. 17. The switch element is composed of a MOSFET, the rectifying element is replaced by a parasitic diode of the MOSFET, and the gate electrode of the switch element is connected to one end of a secondary winding. Drive circuit of semiconductor switch element of. 18. The semiconductor switch according to claim 15, wherein a switch element which is turned off when the light emitting element of the primary side circuit is turned on and is turned on when the light emitting element is turned off is connected in parallel with the photovoltaic element. Device drive circuit. 19. A drain electrode and a source electrode of a switch element composed of a MOSFET are connected to both poles of a photovoltaic element, and a gate electrode of the switch element is connected to an auxiliary winding provided on the secondary side of the transformer. 19. The drive circuit for a semiconductor switch element according to claim 18, wherein the switch element is turned on when an induced electromotive force having a polarity opposite to that of the photoelectromotive force is induced in the secondary winding. 20. The power supply means statically operates the primary side circuit and the secondary side circuit so as to supply power to the secondary side circuit in response to a change in the drive voltage applied from the drive power source to the primary side circuit. 2. An electrostatic coupling means for performing electrical coupling.
A drive circuit for the semiconductor switch element described. 21. A primary side circuit is composed of a series circuit of a light emitting element and a resistor which emit light when a drive voltage is applied, and a secondary side circuit is composed of a photovoltaic element optically coupled to the light emitting element. In the direction in which a voltage having the same polarity as the photovoltaic power generated in the photovoltaic element at the time of power supply is applied to the secondary side circuit, the secondary side circuit and the secondary side circuit are connected via the electrostatic coupling means including a capacitor.
21. A secondary circuit is connected to the secondary circuit.
A drive circuit for the semiconductor switch element described. 22. A semiconductor switch element configured by connecting control terminals of two field effect transistors and one main terminal of each pair of main terminals in common, and one control terminal connected in common A semiconductor relay comprising: the drive circuit according to any one of claims 1 to 21, which supplies a control input to the main terminal of the semiconductor relay.