JPS63208320A - Base driving circuit - Google Patents

Abstract

PURPOSE:To obtain the base driving circuit of a simple constitution by providing a current transformer having one secondary winding which induces a current with the current of the main line of a transistor (TR), a means which rectifies the secondary current on a half-wave basis and applies the current to the base, a switch which short- circuits this means and applies a reverse bias, and a start current switch between the collector and base. CONSTITUTION:When an FET 6 is turned on by a signal source 31, a base current flows to the primary winding 1a of the current transformer 1 and a main TR Q13. The winding ratio 1a/1b of the current transformer 1 is set nearly equal to the hFE of the Q13 and its black point side is plus. The Q13 turns on with the current flowing through the winding 16, a diode 2, the base and emitter of the Q13, and a reverse bias power source 4 and the power source 4 charges itself. The signal source 13 is turned on to turn of the FET 6 with the positive signal of a signal source 15 and then turns on an FET 5, and consequently winding 1b is short-circuited to apply a reverse bias to between the emitter and base of the Q13, which turns off speedily. A diode D14 allows a negative feedback current to flow when a load 12 is inductive, and a D11 and a resistance 16 are used to reset the current transformer 1. In this constitution, a driving power source reduces unnecessary bias power source capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transistor base drive circuit used in a high power output transistor inverter or chopper.

[Conventional technology]

In an inverter or chopper that uses transistors to output high power, the base current of the transistor is large. That's why! ! A water source is required. Furthermore, when turning off the transistor, it is preferable to apply the full reverse bias voltage between the base and emitter of the transistor in order to rapidly eliminate accumulated carriers corresponding to the on-period of the transistor and reduce loss during off-time.

Conventionally, for this kind of purpose, a circuit proposed in, for example, Japanese Patent Publication No. 61-262089 shown in FIG. 85 has been used. To explain Figure 5 below, 10a
, 10b is a DC power supply, 12 is a load circuit, 13a, 13b
is the main transistor, 14a and 14b are diodes, 15a and 15b are base drive circuits, and 1 is a current transformer installed on the AC bus, and its secondary winding m 1 a
, 1b are base drive circuits 15a and 15b, respectively.
It is connected to the. (The base drive circuit 15b has exactly the same configuration as the base drive circuit 15a, and its operation is the same except that it is out of phase with the base drive circuit 15a by 180 degrees, so the explanation will be omitted below.) Input terminal of the amplification control circuit 25 When an off signal is applied to 25a and 25b, transistor 19 is turned on and transistor 18 and transistor 22 are turned off. transistor 19
is turned on, a current flows through the drive power supply 21, the resistor 20, the transistor 19, and the base-emitter path of the main transistor 13a, and the main transistor 13a begins to conduct. And the main transistor 16 from the DC power supply 10a
a, current begins to flow n in the path of the primary winding 1a1 of the current transformer 1 and the load circuit 12.

A voltage indicated by a black dot is induced in each winding of the current transformer 1, and a current flows through the base-emitter path of the secondary winding 1a, the diode 17, the transistor 19, and the main transistor 13a. is completely turned on. Next, the input terminals 25a, 2 of the amplification control circuit 25
When an off signal is applied to 5b, transistor 19 is turned off, and transistors 18 and 22 are turned on. The transistor 18 is turned on, the current supply from the current transformer 1 is stopped, and the transistor 19 is turned off, so that the base radio wave of the main transistor 13a becomes zero. Then, since the transistor 22 is turned on, a current flows from the reverse bias power supply 24 through the emitter-base of the main transistor 13a, the resistor 26, and the collector-emitter of the transistor 22, and the main transistor 13a is applied with a reverse bias and is rapidly turned off. In this way, this pace drive circuit applies base current energy to all main transistors more effectively than the current transformer when it is on, and reverse bias voltage when it is off. Can be applied.

[Problem that the invention seeks to solve]

However, in the conventional pace drive circuit, it is necessary to have a drive power supply and a reverse bias power supply, and it is also necessary to insulate from the OVt level, which not only complicates the circuit configuration and causes uninterrupted circuits, but also There were problems that caused interference. This problem is especially a problem in No.-7 bridge circuits and bridge circuits.

[Means to solve problems]

The invention provides a means for completely removing the drive power source in the base drive circuit, in which at least one of the transistors in the pace drive circuit used in an inverter or a chopper is energized by the current in the main line of the transistor and causes a current to flow. a current transformer that connects the secondary winding; base current supply means for full-half-wave rectification of the current induced in the secondary winding and supply to the base of the transistor; and a first switch means for applying a reverse bias voltage to the transistor, and a second switch means connected between the collector and the base of the transistor to supply a starting current. A complete base drive circuit with characteristics is proposed.

[Written by Kawa]

In the pace drive circuit according to the present invention, the starting current for turning on the main transistor is supplied from the main line, and the steady base current is supplied to the transformer of the main line. No longer needed. As for the reverse bias power supply, the power supply capacity needs to be small because it has a self-charging effect. [Embodiment] Figure 1 shows an embodiment of the invention, in which the DC power supply 10 is connected to the load circuit 12 and the first winding of the current transformer 10. It is connected to the line 1a1 and the main transistor 16 to form a main circuit. An N-type FET 6 is connected in parallel between the collector and base of the main transistor 16, and the main transistor hfe(z,%) is equidynamically turned on. A positive signal basin occurred from 61,
N-type FET 6 '11'' is turned on. When N-type FET 6 is turned on, the load circuit 12 and current transformer 1 are connected from the DC power supply 10.
A base current begins to flow into the main transistor 16 through the path of the next winding 1a and the base Φ emitter of the main transistor 13. Here, the winding 1a of the current transformer 1 has one turn, and the winding 1b has 10 to 100 turns, which is approximately the same value as the value of hfe of the main transistor 16. And is each winding of current transformer 1 on the black dot side? A positive voltage is generated, and a current flows from the winding 1b to the diode 2, the base/emitter of the main transistor 16, and the reverse bias power supply 4, and the main transistor 16
is completely turned on. At the same time, the reverse bias power supply 4 is charged.

Next, to turn off the main transistor 16, the on signal source 3
1ytO, and all positive signals are generated from the off signal source 51. When the ON signal source 61 is 0, the N-type FET 6 is turned off.

Also, the N-type FE″r5 turns on, and the winding 1b of the current transformer 1
The fermentation current is short-circuited by the N-type 11'ET5 via two diodes. Furthermore, by turning on the N-type FET 5, the reverse bias power supply 4 is connected to the emitter of the main transistor 16.
Applied as a reverse bias to the base of the main transistor 1
The accumulated carriers of 6 are rapidly canceled and turned on. The diode 14 is connected in parallel and in the opposite direction to the main transistor 16 so that the load circuit 12 carries an inductive feedback current.

The diode 11 and the resistor 16 are for resetting the current transformer 1.

FIG. 2 shows another embodiment of the present invention, and the difference from the circuit shown in FIG. 1 is the on-starting current of the main transistor 16. In this circuit, all of the energy of the snubber circuit can be effectively utilized because it is provided through the resistor 66 from the snubber circuit formed by the diode 61 and the capacitor 62.

FIG. 6 is a wiring diagram applied to a full half-bridge inverter according to the present invention, in which two DC power supplies 10, 10', main transistors 15, 13' of 21, and respective parallel-connected diodes 14, 14', 2 The secondary winding mk current transformer 1 and the load circuit 12 are connected as shown in the figure, the main transistor 16 is driven by the base drive circuit 15, and the main transistor 16' is driven by the base drive circuit 15'. . In the current transformer 1, the two windings 1b and 1b' have opposite polarities and are symmetrical, so the reset diode 1 shown in FIG.
1 and resistor 16tj: unnecessary.

FIG. 4 shows still another embodiment of the present invention, which includes a more specific circuit formed by on-off signal sources 71 - an on-signal source 61 and an off-signal source 51.

First, to explain the ON signal source 61, when the output of the ON/OFF signal source 71 is a high level H signal, the diode 65
? 11'' to the primary winding of the pulse transformer 66, the secondary winding generates an on signal through the diode 62, and the on signal is applied between the gate and source of the N-type FET 3. , the resistor 64 is for resetting the pulse transformer 66, and the resistor 68 is for discharging the gate current accumulated in the N-type FET 3.The output of the on/off signal source 71 is at a low level. At this time, the ON signal source 61 has an output of 0.

Next, explaining the off signal source 51, when the output of the on/off signal source 71 is an H signal, it is applied to the primary winding of the pulse transformer 56 through the diode 58t, and the second
The H signal is supplied from the next winding through a diode 55 to each gate of a P-type FET 52 and an N-type FET 53 that constitute a signal inverter. However, the source of P-type FET52 and N
The drains of type FETs 53 are interconnected to receive an off signal #
The source of the P-type FET 52 is connected to a Zener diode 69 and a capacitor 40 via a diode 66 and a resistor 67 from the collector of the main transistor 16.
A DC voltage that has been stepped down and smoothed by a parallel circuit is applied. Therefore, when the output of the on/off signal source 71 is an H signal, the output of the off signal source 51 is an L signal, that is, 0 as an off signal. Conversely, when the ON/OFF signal source 71 is an L signal, the output of the OFF signal source 51 is an H signal. still,
The resistor 57 is for resetting the pulse transformer 56,
The resistor 54 is for discharging the charges accumulated in the gate capacitance of the P-type FET 52 and the N-type FET 53.

Incidentally, in FIGS. 1 to 4, the FETs 5, 6, etc. can be replaced with other types of switching elements to achieve the same effect.

〔Effect of the invention〕

As mentioned above, the on-drive current of the main transistor is the current transformer of the main line! 11M effect is supplied. Since the reverse bias power supply for turning off has a self-charging effect, it is economical in terms of the number of components and power efficiency.

[Brief explanation of the drawing]

1, 2 and 4 are examples of the present invention,
FIG. 6 is a wiring diagram applied to the half-bridge inverter of the present invention, and FIG. 5 is a diagram of a conventional base drive circuit. 1...Current transformer 10, 10'...DC power supply 2
...Diode 13, 13'-main transistor 4
・-・Reverse bias power supply 5, 6...N-type FET61・
...On signal source 15, 15', 15a, 15b...Base drive circuit 5
1... Off signal source 21... Drive power supply 12...
・Load circuit 24...reverse bias power supply 10a,
10b... DC power supply 25... Amplification control circuit

Claims (1)

[Scope of Claims] A current transformer having at least one secondary winding that is energized by the current in the main line of the transistor to induce a current in a base drive circuit of a transistor used in an inverter or a chopper; base current supply means that half-wave rectifies the current induced in the next winding and supplies it to the base of the transistor; and a first switch means that short-circuits the base current supply means and applies a reverse bias voltage to the transistor. and second switch means connected between the collector and base of the transistor to supply a starting current.