JPH0159838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a base driver circuit for an inverter/transistor, and an object of the present invention is to provide a base driver circuit for a transistor/inverter that can stably perform a base drive operation of a transistor/inverter. It is something.

An embodiment of the invention is shown in FIGS. 1 to 3. That is, the base driver circuit of this transistor inverter is connected to the first and second DC voltage sources.
A series power supply circuit V _D in which V _D1 and V _D2 are connected in series and the connection midpoint n of the two DC voltage sources V _D1 and V _D2 is connected to the emitter side of the transistor inverter T _r0 , and this series power supply circuit V _D The first and second transistors Tr 1 and Tr _{2 are connected in series between both terminals of the inverter transistor Tr 0 and the midpoint n' of the connection is connected to the base side of the inverter transistor Tr 0 , and} the external control circuit (not shown) a photocoupler PC that receives a control signal for switching the inverter transistor Tr ₀ and operates on and off in a predetermined switching cycle;
a third transistor Tr ₃ connected between both terminals of the first DC voltage source V _D1 and turned on and _off in response to the photocoupler PC; a fourth transistor that turns on the first transistor Tr ₁ ;
Tr ₄ and a fifth transistor Tr ₅ that turns off _the second transistor Tr ₂ in response to the ON operation of the third transistor Tr ₃ ; The first transistor Tr ₁ is turned on, the second transistor Tr ₂ is turned off, and the first DC voltage source V _D1 is applied between the base and emitter of the inverter transistor Tr ₀ , and the third transistor Tr _{3 is} turned on. The inverter transistor is turned off by turning off the first transistor Tr ₁ and turning on the second transistor Tr ₂ .
The first DC voltage source between the base and emitter of Tr ₀
By applying a second DC voltage source V _D2 having a polarity opposite to that of V _D1 , the inverter transistor Tr ₀ is turned on and off.

The fifth transistor drives the second transistor Tr ₂ off in response to the on operation of the third transistor Tr ₃
transistor Tr ₅ and the third transistor
Tr ₃ is connected via a sixth transistor Tr ₆ which is also connected between both terminals of the first DC voltage source V _D1 , and transistor Tr ₃ is on, transistor Tr ₆ is off, and transistor Tr ₅ is on. A signal transmission operation is performed in which the transistor Tr 2 is turned off and the transistor Tr ₂ is turned off.

The transistors Tr ₁ , Tr ₂ , Tr ₃ , Tr ₆ are NPN
The transistors Tr ₄ , Tr ₅ , and Tr ₇ are of PNP type.

The diodes D ₁ and D ₂ are connected to the third transistor Tr ₃
A sixth transistor Tr ₆ (this transistor Tr ₆ controls on/off of the second transistor Tr ₂ via the fifth transistor Tr ₅ ) which turns off in response to the on operation of the transistor Tr 6 ; _tr3
This is to separate the fourth transistor Tr _{4 from interfering with the fourth transistor Tr 4} which turns on in response to the off operation of the fourth transistor Tr 4 .

A seventh transistor Tr ₇ connected in series to the phototransistor Tr _p of the photocoupler PC and a Zener diode that biases this transistor Tr ₇
The disadvantage of circuits such as ZDs is that when a power outage occurs while the transistor/inverter is operating, the current flowing through the base driver circuit gradually decreases, causing the transistors in the circuit to be used in the secondary destruction range. This is a protection circuit to avoid this, and operates as follows.

When the first DC voltage source V _D1 is normal, a Zener voltage is applied to the Zener diode ZD, which turns on the transistor Tr ₇ and transfers the input control signal from the external control circuit to the photocoupler PC to this transistor.
The third transistor Tr ₃ and the following transistors Tr ₄ , Tr ₅ , Tr ₆ ,
_However , when a power outage occurs and the voltage level of _the first DC voltage source V _D1 begins to gradually decrease, the Zener diode
No reverse current flows to ZD, and the seventh
The transistor Tr ₇ in the circuit is turned off to prevent the input signal from the external control circuit to the photocoupler PC from being transmitted to the amplifier stage of the base driver circuit of this transistor inverter, and the transistor in the circuit is in the secondary destruction region. Avoid being used.

With this configuration, the photocoupler operates on and off in response to control signals from an external control circuit.
In response to the PC, the first transistor Tr ₁ is on and the second transistor Tr ₂ is off, and the first transistor Tr ₁ is off and the second transistor Tr ₂ is on. When the transistor Tr ₁ is on and the transistor Tr ₂ is off, a first DC voltage source is applied between the base and emitter of the inverter transistor Tr ₀ as shown in Figure 2, which shows the transistors Tr ₁ and Tr ₂ as switches. V _D1 is applied to drive inverter transistor Tr ₀ on, transistor Tr ₁ is off, transistor
In the opposite state where Tr ₂ is on, as shown in Figure 3, a reverse bias is applied between the base and emitter of the inverter transistor Tr ₀ by the second DC voltage source V _D2 to ensure that the inverter transistor Tr ₀ is turned on. The inverter transistor Tr ₀ can be turned off and turned on and off reliably, and the circuit will not become unstable even if there are changes in the ambient temperature or other conditions or constants. It is possible to improve the reliability of

Another embodiment of the invention is shown in FIG. That is, the base driver circuit of this transistor inverter uses diodes D ₁ and D ₂ and the sixth transistor Tr ₆ to transmit the output of the third transistor Tr ₃ to the fifth transistor Tr ₅ in the above embodiment. Instead of using a circuit consisting of
Transistors T′r ₆ and Tr ₈ connected between both terminals of the series power supply circuit V _D (T′r ₆ is PNP type, Tr ₈ is NPN
This type of series circuit is constructed by turning on transistor Tr ₃ , which turns _on transistor T
is on (transistor Tr ₈ is always on) and the fifth
transistor Tr ₅ is turned off, thereby turning off the second transistor Tr 5.
This is to turn off the transistor Tr ₂ ,
In response to the ON operation of the third transistor Tr ₃ ,
the first transistor through the fourth transistor
The configuration for turning on Tr ₁ is the same as in the previous embodiment.

Then, the transistor Tr ₈ is connected to the inverter transistor Tr ₀ by the second DC voltage source V _D2 .
In the state shown in FIG. 3 in which a reverse bias is applied between the base and emitter of the fifth transistor,
Tr ₅ turns on (at this time, the first transistor
Tr ₁ is off and the second transistor Tr ₂ is on), and the second DC voltage source
When the supply of V _D2 is stopped, the current flowing through the fifth transistor Tr ₅ causes the smoothing capacitor C ₂ of the DC voltage source V _D2 to connect to this DC voltage source.
To avoid being charged to a potential opposite to V _D2 ,
This is for blocking the current inflow path.

The other configurations and operations are the same as those of the previous embodiment.

In this way, the third transistor Tr ₃ is turned on.
Since the off signal is transmitted to the second transistor Tr ₂ via the two transistors T'r ₆ and Tr ₈ connected in series between both terminals of the series power supply circuit V _D , the third transistor A fourth transistor transmits the on/off signal of Tr ₃ to the first transistor Tr ₁ .
The isolation between the transistor Tr ₄ and the transistor Tr ₆ can be ensured, and the base drive of the transistor inverter can be performed with stable operation.

Furthermore, due to the presence of transistor Tr ₈ , the second
Even if the supply of the DC voltage source V _D2 is stopped, the current flowing into the smoothing capacitor C ₂ of the DC voltage source V _D2 through the transistor Tr ₅ will surely prevent the reverse potential from being charged. This allows for even more reliable operation.

As described above, the transistor/inverter base driver circuit of the present invention connects the first and second DC voltage sources in series, and connects the midpoint between the two DC voltage sources to the emitter side of the inverter transistor. a series power supply circuit, first and second transistors connected in series between both terminals of the series power supply circuit and having their connection midpoints connected to the base side of the inverter transistor; and both ends of the first DC voltage source. a third transistor connected between the terminals and turned on and off in response to a control signal input from an external control circuit; and a third transistor that turns on and off in response to the turn-on operation of the third transistor. a fourth transistor; and a fifth transistor that turns off the second transistor in response to an on operation of the third transistor;
The base transistor of the inverter transistor is turned on and the second transistor is turned off.
A first DC voltage source is applied between the base and emitter of the inverter transistor, and the first transistor is turned off by the off operation of the third transistor, and the second transistor is turned on to apply the first DC voltage source between the base and emitter of the inverter transistor. The inverter transistor is turned on and off by applying a second DC voltage source with the opposite polarity to the current DC voltage source, so even if there are fluctuations in ambient temperature or other conditions, the transistor - It has the effect of stably performing the base drive operation of the inverter.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the invention, FIGS. 2 and 3 are schematic circuit diagrams showing its operation, and FIG. 4 is a circuit diagram showing another embodiment of the invention. V _D ...Series power supply circuit, V _D1 ...DC voltage source (first),
V _D2 ...DC voltage source (second), Tr ₀ ...inverter transistor, Tr ₁ ...transistor (first), Tr ₂ ...
Transistor (second), Tr ₃ ... transistor (third), Tr ₄ ... transistor (fourth), Tr ₅ ... transistor (fifth), Tr ₆ ... transistor (sixth),
D ₁ , D ₂ ... diode, PC... photocoupler, T′r ₆ ,
Tr ₈ ...Transistor.

Claims (1)

[Claims] 1 A series power supply circuit in which the first and second DC voltage sources are connected in series and the midpoint of the connection between these two DC voltage sources is connected to the emitter side of the inverter transistor, and a series power supply circuit is connected between both terminals of this series power supply circuit. A control signal input from an external control circuit is connected between first and second transistors that are connected to each other and whose midpoints are connected to the base side of the inverter transistor, and both terminals of the first DC voltage source. a third transistor that turns on and off in response to the turn-on operation of the third transistor; a fourth transistor that turns on the first transistor in response to the turn-on operation of the third transistor; and a fourth transistor that turns on the first transistor in response to the turn-on operation of the third transistor; a fifth transistor that turns off the second transistor in response, and turns on the first transistor when the third transistor turns on;
The second transistor is turned off and the inverter is turned off.
A first DC voltage source is applied between the base and emitter of the transistor, and the third transistor is turned off to turn off the first transistor, and the second transistor is turned on to drive the voltage between the base and emitter of the inverter transistor. A transistor characterized in that the inverter transistor is turned on and off by applying a second DC voltage source having a polarity opposite to that of the first DC voltage source.
Inverter base driver circuit.