JPH066715Y2 - Ring choke converter drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a drive circuit of a ringing choke converter which obtains its converter function based on the on / off operation of a switching transistor.

[Conventional technology]

FIG. 2 is a diagram showing a drive circuit of a conventional ringing choke converter. In the figure, 4 is a switching transistor whose collector is connected to one end of the main winding 8a of the transformer 8, and the base current to the switching transistor 4 is supplied from the base feedback winding 8b of the transformer 8 to the resistor 7 Is supplied via a parallel connection circuit (impedance circuit) Z between the capacitor and the capacitor 6. Here, the capacitor 6 is generally called a speed-up capacitor, and plays a role of shortening the rise / fall time during the switching operation of the switching transistor 4 and reducing the switching loss. The resistor 7 serves to supply the base current required to maintain saturation in the ON state of the switching transistor 4. The polarity of the base feedback winding 8b of the transformer 8 is determined so that a positive feedback action is produced by the current flowing through the collector of the switching transistor 4.

In the figure, 1 and 2 are input terminals, 3 is a resistor, 5 is a control circuit, 8c is an output winding of the transformer 8, 9 is a diode, 10 is a capacitor, and 11 and 12 are output terminals.

[Problems to be solved by the device]

However, according to the drive circuit of such a conventional ringing choke converter, when the input voltage via the terminals 1 and 2 rises, the power consumed in the impedance circuit Z rapidly increases, which causes a problem that efficiency deteriorates. there were. That is, the voltage generated in each winding of the transformer 8 is stabilized while the switching transistor 4 is off, but changes depending on its input voltage while the switching transistor 4 is on. For this reason, when the input voltage rises, the power consumed by the impedance circuit Z rapidly increases, which causes a problem that efficiency deteriorates.

[Means for Solving the Problems]

In order to solve such a problem, the present invention connects the collector to one end of the main winding, the base to one end of the feedback winding through an impedance circuit, and the emitter to the other end of the feedback winding. In a drive circuit of a ringing choke converter having a main switching transistor consisting of the following, an additional winding formed by connecting one end to the other end of the feedback winding and the anode connected to the other end of this additional winding A diode, a capacitor inserted between the cathode of the diode and one end of the additional winding, and a connection point between the capacitor and the cathode of the diode, the collector of which is connected via a second impedance circuit, and A drive transistor whose emitter is connected to the base of the main switching transistor and a base of this drive transistor. It is obtained by constituting the drive circuit of the ringing choke converter induced voltage based on the supply current to the winding and a bleeder circuit for applying by dividing.

[Action]

Therefore, according to the present invention, the drive transistor is turned on based on the divided voltage applied through the bleeder circuit during the on period of the main switching transistor, and is induced through the additional winding during the off period of the main switching transistor, through the diode. The base current is supplied to the main switching transistor via the second impedance circuit and the drive transistor based on the charging voltage of the capacitor that is charged as a result.

〔Example〕

Hereinafter, the ringing choke converter according to the present invention will be described in detail.

FIG. 1 is a diagram showing an embodiment of a drive circuit of this ringing choke converter, and the same reference numerals as those in FIG. In the figure, 1
Reference numeral 9 is an additional winding formed by connecting one end to the other end of the base feedback winding 8b of the transformer 8, 14 is a diode formed by connecting the anode to the other end of the additional winding 19, and 15 is this diode 14 Is a capacitor which is connected between the cathode of 1 and the one end of the additional winding 19 with its positive electrode side being the diode 14 side, and 17 is this capacitor 15 and the diode 1
A drive transistor, 18 having its collector connected to the cathode of 4 via an impedance circuit 16 and having its emitter connected to the base of the main switching transistor 4, is connected in parallel to the base feedback winding 8b. The bleeder circuit divides the voltage induced in the base feedback winding 8b. The divided voltage generated at the midpoint of the bleeder circuit 18 is applied to the base of the drive transistor 17, and an impedance circuit is provided between one end of the base feedback winding 8b and the base of the main switching transistor 4. 13 is connected.

Now, in the drive circuit of this ringing choke converter, when a voltage is applied between its input terminals 1 and 2,
A minute current is supplied to the base of the switching transistor 4 via the resistor 3, and a current of h _FE times the minute base current is supplied as a collector current to the switching transistor 4 via the main winding 8a of the transformer 8. Flowing. When a current flows through the main winding 8a of the transformer 8, a voltage is induced in the base feedback winding 8b, and based on the voltage induced in the base feedback winding 8b, the voltage is applied to the base of the switching transistor 4 via the impedance circuit 13. Allow more current to flow. That is, when a current flows through the main winding 8a, a voltage is induced in the base feedback winding 8b so that a further current flows through the impedance circuit 13 to the base of the switching transistor 4, which causes the switching transistor 4 to completely operate. Is turned on.

On the other hand, the collector current to the switching transistor 4 increases linearly due to the inductance of the main winding 8a of the transformer 8. However, the upper limit of the collector current flow capability of the switching transistor 4, that is, I _CP = h _FE When reaching I _B (I _CP : peak value of collector current, h _FE : amplification factor, I _B : base current), the switching transistor 4 is sharply cut off by the control circuit 5.

When the switching transistor 4 is turned off, the capacitors 10 and 15 are charged via the diodes 9 and 14 based on the voltage induced in the output winding 8c and the additional winding 19. That is, while the switching transistor 4 is on, it is blocked by the diodes 9 and 14, so that the capacitors 10 and 15 are not charged based on the voltage induced in the output winding 8c and the additional winding 19, but When the switching transistor 4 is turned off, based on the voltage induced in the output winding 8c and the additional winding 19, the capacitor 1 is connected via the diodes 9 and 14.
A charge stream flows into 0 and 15.

After a certain period of time, when the switching transistor 4 is turned on again based on the operation of the control circuit 5, the voltage induced in the base feedback winding 8b based on the current supplied to the main winding 8a is generated in the bleeder circuit 18. As the divided voltage across the point,
It is applied to the base of the drive transistor 17. The drive transistor 17 is turned on by the divided voltage via the middle point of the bleeder circuit 18, and the impedance circuit 16 and The base current is supplied to the switching transistor 4 via the drive transistor 17.

By repeating such an operation, the DC voltage rectified and smoothed by the capacitor 10 and the diode 9 is supplied to the load (not shown) via the output terminals 11 and 12.

As described above, according to the drive circuit of the ringing choke converter of the present embodiment, the voltage induced in the additional winding 19 while the switching transistor 4 is off is rectified and smoothed by the diode 14 and the capacitor 15, and the impedance The base of the drive transistor 17 is connected to the base of the switching transistor 4 via the circuit 16 and the drive transistor 17, and the base of the drive transistor 17 is connected to the middle point of the bleeder circuit 18 connected in parallel to the base feedback winding 8b. 1
It becomes possible to always supply the base current to the switching transistor 4 at a constant voltage via 7, and it becomes possible to keep the loss of the drive circuit due to the increase of the input voltage substantially constant, and to increase the input voltage. It is possible to suppress a rapid increase in power consumption of the drive circuit that accompanies it and prevent the efficiency from deteriorating. Further, since a constant base current can be supplied to the switching transistor 4 even when the input voltage changes, there is an effect that the dynamic range of the control circuit 5 can have a margin.

Although the bleeder circuit 18 is connected in parallel to the base feedback winding 8b in the present embodiment, it is arranged not to be connected in parallel to the additional winding 19 and the divided voltage generated at the midpoint thereof is driven. It goes without saying that it may be configured so that it is applied to the base of the transistor 17.

[Effect of device]

As described above, according to the drive circuit of the ringing choke converter according to the present invention, the collector is provided at one end of the main winding, the base is provided at one end of the feedback winding through the impedance circuit, and the other end is provided at the other end of the feedback winding. In a drive circuit of a ringing choke converter having a main switching transistor with an emitter connected, an additional winding with one end connected to the other end of the feedback winding and the anode at the other end of this additional winding. Connect the connected diode, the capacitor inserted between the cathode of this diode and one end of the additional winding, and its collector via the second impedance circuit at the connection point between this capacitor and the cathode of the diode. Drive transistor connected by connecting its emitter to the base of the main switching transistor And a bleeder circuit that divides and applies an induced voltage based on the current supplied to the main winding to the base of the drive transistor, so that the voltage applied via the bleeder circuit during the ON period of the main switching transistor is The drive transistor is turned on based on the piezo voltage, and based on the charging voltage of the capacitor that is induced in the additional winding and charged via the diode during the off period of the main switching transistor, via the second impedance circuit and the drive transistor. Since the base current is supplied to the main switching transistor, it is possible to prevent a rapid increase in power consumption of the drive circuit due to an increase in input voltage and prevent deterioration in efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a drive circuit of a ringing choke converter according to the present invention, and FIG. 2 is a diagram showing a drive circuit of a conventional ringing choke converter. 4 ... Switching transistor, 8 ... Transformer, 8
a: main winding, 8b: base feedback winding, 13: impedance circuit, 14: diode, 15: capacitor, 16: impedance circuit, 17: drive transistor, 18: bleeder circuit, 19 ...... Additional winding.

Claims (1)

[Scope of utility model registration request] 1. A main switching transistor having a collector connected to one end of a main winding, a base connected to one end of a feedback winding through an impedance circuit, and an emitter connected to the other end of the feedback winding. In a drive circuit of a ringing choke converter, an additional winding formed by connecting one end to the other end of the feedback winding, a diode formed by connecting an anode to the other end of the additional winding, and a cathode of the diode A capacitor inserted between the capacitor and one end of the additional winding, and a collector of the capacitor connected to a connection point between the capacitor and the cathode of the diode via a second impedance circuit, and an emitter of the capacitor connected to the main electrode. A drive transistor connected to the base of the switching transistor and the base of the drive transistor to the main winding. Ringing choke converter drive circuit comprising a bleeder circuit for applying an induced voltage based on the supply current divide.