JPS61247273A - Switching transistor driving system - Google Patents

Abstract

PURPOSE:To effectively switch a switching transistor driving system by generating a voltage by the collector current of a transistor flowing to the primary coil of a transformer to an auxiliary coil, and supplying a base current from this, thereby reducing a power loss. CONSTITUTION:To drive a switching transistor (Tr1), an auxiliary coil NP2 in provided at the primary side of the transistor Tr1 and wound in the same direction as the primary side coil NP1. A voltage V2 generated in the coil NP2 is supplied as the base current of the Tr1 by the collector current Ic of the Tr1 flowing to the coil NP1. Thus, the base current Ib of the Tr1 is supplied by the voltage v1 of the primary side coil NP3 of the transformer Tr to start a collector current Ic flowing. As a result, a voltage V2 proportional to the operating time of the Tr1 and the winding ratio of the coil NP1:NP2 is generated in the auxiliary coil NP2, thereby controlling the base current Ib.

Description

[Detailed Description of the Invention] [Summary] In a switching transistor drive system, when on/off control is performed by a switching transistor (hereinafter referred to as Tr) of a DC voltage via a switching transformer, the current flowing through the transformer causes the It is configured to control the base current of the Tr, improve the turn-on/off loss of the Tr, and enable efficient switching with less heat generation.

[Industrial application field]

The present invention relates to a switching transistor drive method that performs efficient switching.

A method widely used as a direct current constant voltage power supply for most of recent electronic devices is a method of stabilizing the output voltage by controlling the conduction period or operating frequency of a transistor or thyristor.

There has been a demand for a switching regulator system that is more efficient and has less power loss.

[Prior art and problems to be solved by the invention] FIG. 4 is a circuit diagram illustrating a conventional switching transistor drive system, and FIG. 5 is an operating waveform diagram in FIG. 4.

FIG. 4 shows a method for driving a transistor of a forward converter type switching regulator, which is an example of a switching regulator, and FIG. 5 shows its operating waveform.

Note that Vin, Vs, and Vout are DC power supply voltages, Vce is the collector-emitter voltage of Tri, and Ib is the base current.

Ic indicates the coctor current, respectively.

Also, transformer T1. The black mark on the T2 coil indicates the beginning of winding of the coil, NPI indicates the primary side of transformer T1, NSI indicates the secondary side of transformer T1, NF2 indicates the primary side of transformer T2, NS
3 indicates the secondary side of the transformer T2.

The DC power supply voltage Vs is pulsed by turning on/off the Tr2, and thereby a predetermined voltage is induced in the NF2 and applied to the base of the Tri. Trl is now shown in Figure 5 (A).
A base current Ib flows as shown in FIG.

Furthermore, Tri is on/off controlled by this base current 1b, and a collector current 1c shown in FIG. 5(B) flows. The collector-emitter voltage Vce at this time has a waveform shown in FIG. 5(C).

Note that the resistor R2 is a resistor that limits the base current Ib of Trl, and the diode D1 is intended to pull out minority carriers from the base region when cutting off Tri, thereby shortening the accumulation time and turn-off time of Trl. . Also, resistor R3, capacitor CI, and diode D2 are transformer T.
This constitutes the No. 1 reset circuit.

A predetermined AC voltage is taken out from the NSI of the transformer T1 by turning the power supply voltage Vin on and off (for example, turned on and off at a frequency of 50 KHz), and this voltage is applied to the diode D3. D4, choke coil CI, and capacitor C2 to rectify and smooth the desired DC constant voltage Vout to the load side.

However, as shown in Figures 5(B) and (C), Tri
In the transition period (turn-off time) when the current changes from the saturated state to the cut-off state, (al', as shown in part (a), the current /
Waveform "namari" occurs in both voltage waveforms. When such a "slug" occurs, a large amount of power is lost in this section, causing problems with the heat generation of the Tri and the safe operating area.

[Means for solving problems]

FIG. 1 shows a circuit diagram illustrating the principle of a switching transistor drive system according to the present invention.

Figure 1 shows the components shown in Figure 4, an auxiliary coil NP2 on the primary side of the transformer T1 that has the same winding direction as the coil NPI, and a voltage v2 generated in the auxiliary coil NP2 by the collector current 1c of the transistor Tri flowing through the coil NPI. supply means X for supplying the base current Ib of the transistor Tri;

[Effect]

The voltage Vl generated in the coil NP3 causes the transistor T
The base current 1b of ri is supplied, and the collector current Ic starts to flow. Therefore, a voltage v2 proportional to the operating time of the transistor Tri and the turns ratio of the coil NPI:NP2 is generated in the auxiliary coil NP2 of the transformer T1.
The base current Ib is controlled by this voltage v2.

This improves the ``slug'' of the transistor Tri's (al, (a) portions) and enables efficient switching with less power loss.

〔Example〕

The gist of the present invention will be explained in detail below with reference to the -W embodiment shown in FIGS. 2 and 3.

FIG. 2 is a diagram for explaining one embodiment of the present invention, and FIG. 3 is a diagram for explaining another embodiment of the present invention. Note that the same reference numerals refer to the same objects throughout the plan.

Next, the operation of this embodiment will be explained. 2(A) and 3(A) are circuit diagrams of this embodiment, and FIG. 2(B) and 3(B) are characteristic diagrams of the base current 1b of this embodiment, respectively. . Further, the embodiment shown in FIG. 2 shows a case where the base current rb is improved at turn-on and turn-off times, and the embodiment shown in FIG. 3 shows a case where only the turn-off time is improved.

The supply means X of this embodiment shown in FIGS. 2 and 3 has one end connected to the winding start side of the auxiliary coil NP2, and the other end connected to the transistor T.
Connected to the base side of ri. Furthermore, auxiliary coil NP2
The winding end side of is connected to the winding end side of coil NP3 on the output side of wire ring T2 (drive transformer).

The embodiment shown in FIG. 2 is an embodiment in which a capacitor C and a resistor R are connected in series as the supply means X, and the third
The illustrated embodiment is an embodiment in which a diode D and a resistor R are connected in series.

In the case of the embodiment shown in FIG. 3, the resistor R is connected to the base so that current flows to the base only when turned off.
Diode D is connected with the side connected to the (+) side as the (+) side.

By turning on the transistor Tr2 connected to the input side NS3 of the drive transformer T2, the output side N
A voltage V1 is generated at the P3 terminal. This voltage V1 causes a base current r to flow through the resistor R2 to the transistor Tri.
b is supplied, and collector current 1c begins to flow.

This collector current 1c generates a voltage v2 across the auxiliary coil NP2 newly provided in the wire T1, which is proportional to the operating time ratio (referred to as duty ratio) of the transistor Trl and the turns ratio of the coil NPI to NP2. Note that the voltage v2 is proportional to the duty ratio of the transistor Tri.

This voltage v2 is used to control the base current 1b of the transistor Tri. That is, the base current 1b is controlled by the collector current Ic of the transistor Tri.

In the case of the embodiment shown in Fig. 2, as shown in Fig. 2 (B), when the turn-on is turned on, the control is performed to overdrive to speed up the start-up, as shown by the solid line, and when the turn-off is turned on, the control is performed such that the start-up is accelerated, and when the turn-on is turned on, the control is performed so that the rise is accelerated. This will increase the recruitment of the minority carriers currently in the workforce. This improves the ``slug'' at turn-on and turn-off. Note that the dotted line indicates the characteristics before improvement.

In the embodiment shown in FIG. 3, as shown in FIG. 3(B), the characteristics of the diode D are controlled to increase the extraction of minority carriers mixed in the base only during turn-off, thereby reducing the "Namari" effect at turn-off. This is an example for improving. By this method, the storage time and turn-off (turn-on) time of the transistor Tri can be shortened, and the transistor Tri
This makes it possible to reduce heat generation.

(Effects of the Invention) According to the present invention as described above, there is an effect that "sluggishness" in the turn-on/turn-off portion during transistor switching is improved, and efficient switching with less power loss is possible.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram explaining the principle of a switching transistor drive system according to the present invention, FIG. 2 is a diagram explaining one embodiment according to the present invention, and FIG. 3 is a diagram explaining another embodiment according to the present invention. FIG. 4 is a circuit diagram explaining a conventional switching transistor driving method, and FIG. 5 is an operation waveform diagram in FIG. 4. 1 to 4, C, CI, and C2 are capacitors, C1l is a choke coil, D, Di to D5 are diodes, R, R1-R3 are resistors, T1. T2 is a coil, Trl and Tr2 are transistors, respectively. (rl)03 0H Leather 2 figure (A) Senior 3 figure (A) Grass 2 times (B) Bush 3- figure (B)

Claims (1)

[Claims] A DC voltage is converted into an AC voltage by on/off control of a transistor (Tr1), and the AC voltage is converted to an AC voltage by a primary coil (NP1) and a secondary coil (NS1) with a predetermined winding ratio. In a device that converts into a predetermined AC voltage in a transformer (T1) and rectifies the predetermined AC voltage to supply a stable DC voltage, an auxiliary winding direction in the same direction as the primary coil (NP1) of the transformer (T1) is provided. The voltage (V2) induced in the auxiliary coil (NP2) by the collector current (Ic) of the transistor (Tr1) flowing through the coil (NP2) and the primary coil (NP1) is the base current of the transistor (Tr1). (Ib); and means (X) for supplying the transistor (Ib) as the base current (Ib) of the transistor (Tr1) is controlled by the collector current (Ic).