JP2000102247A - Ringing choke converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the wasteful consumption power of an activation resistor during oscillation operation by adding a second switching element being provided between an activation resistor and the connection point with a switching element and a switch selection circuit for turning on or off the switching element. SOLUTION: A ringing choke converter circuit is provided with a MOS-FET Q2, where a drain is connected to an activation resistor R1 and a source is connected to the control terminal of a switching element Q1 and a switching circuit 4, that is connected to the positive and negative electrodes of control coil winding N3 and the gate of the MOS-FET Q2 and a DC input voltage VIN, detects a voltage at the negative electrode side of the control coil winding N3, and turns on or off the MOS-FET Q2. Then, the shifting of a power supply to an oscillation operation is detected between detection terminals 4a and 4b of the switching circuit 4, the voltage of a terminal 4c is dropped, and the MOS-FET Q2 is turned off, thus suppressing the wasteful power consumption of the activation resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ringing-choke converter with high efficiency.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a circuit configuration of a conventional general ringing yoke converter.

In FIG. 3, a transformer includes the following components: a transformer T1 having a primary winding N1, a secondary winding N2, and a control winding N3, and a primary winding of the transformer T1 from a positive electrode of a DC input voltage V _IN . A switching element Q1 connected to a drain via a line N1, a control circuit 1 formed between a control winding N3 of a transformer T1 and a gate of the switching element Q1, and a gate of the switching element Q1 from the positive electrode of the DC input voltage V _IN A starting resistor R1 connected therebetween, a rectifying diode D1 having an anode connected to a negative electrode of the secondary winding N2, and a rectifying diode D1 connected between a cathode of the rectifying diode D1 and a positive electrode of the secondary winding N2. Smoothing capacitor C1
And a voltage detection circuit 3 connected between the positive (+) and negative output voltage terminals (-) respectively connected to both terminals of the smoothing capacitor C1, and the output voltage terminals (+) and (-).
And an optical coupling element 2 connected between the voltage detection circuit 3 and the control circuit 1.

Next, the operation of the ringing yoke converter shown in FIG. 3 will be described. When the DC input voltage V _IN is applied, the gate of the switching element Q1 is charged via the starting resistor R1, the potential rises, and the switching element Q1 starts to turn on. The DC input voltage V _IN is applied to the primary winding N1 of the transformer T1 with the positive side being positive, and the control winding N
3 is also induced with a positive voltage on the positive electrode side (however, in the winding of FIG. 3, the one marked with “•” is the positive electrode side).

This voltage is positively fed back to the gate of the switching element Q1 via the control circuit 1, and the switching element Q1 is completely turned on. When the switching element Q1 is turned on, (V _IN / L) * t is applied to the primary winding N1 of the transformer T1.
on (where L is the inductance of the primary winding N1, to
(n: ON time of the switching element Q1), a triangular-wave-shaped primary current 1d that increases with an inclination flows. The ON period of the switching element Q1 is controlled by the control circuit 1. Specifically, the voltage detection circuit 3 detects that the output voltage is about to rise, and sends a negative feedback signal to the control circuit 1 via the optical coupling element 2. The control circuit 1 discharges the gate charge of the switching element Q1 and switches the switching element Q1.
Turn off.

Until the switching element Q1 is turned off, the primary winding N1 of the transformer T1 is １ ／ * L *
(1d) ^Two energies are accumulated. When the switching element Q1 is turned off, the polarity of all the windings of the transformer T1 is inverted by the back electromotive force. Therefore, a secondary current for charging the smoothing capacitor C1 flows from the negative electrode of the secondary winding N2 of the transformer T1 through the rectifying diode D1, and the stored energy is released. When the discharge of the stored energy is completed, the polarities of all the windings of the transformer T1 are inverted again, and the control circuit 1 starts charging the gate of the switching element Q1 again to turn on the switching element Q1. By repeating these series of operations, a ringing-choke converter oscillates and outputs a desired constant voltage Vo.

As described above, the switching element Q1
Is charged via the starting resistor R1 immediately after the start of the power supply. Then, after the oscillating operation of the switching element Q1 starts, charging is performed from the winding N3 of the transformer T1. Therefore, after the start of the oscillation operation, the starting resistor R1 becomes unnecessary for the operation of the power supply. In other words, the starting resistor is provided only for a moment when the power is turned on.

Nevertheless, during the operation of the power supply, a current always flows through the starting resistor R1, and a constant amount of power is wasted.

[0009]

However, in the configuration of the conventional ringing yoke converter described above, it was impossible to suppress wasteful power consumption of the starting resistor during the oscillating operation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-efficiency ringing yoke converter having a function of detecting that the power supply has shifted to an oscillating operation and suppressing wasteful power consumption of a starting resistor.

[0011]

In order to achieve the above object, the present invention provides a transformer having a primary winding, a secondary winding, and a control winding, and a transformer having a DC input voltage terminal having a positive electrode. In a ringing yoke converter that performs a ringing yoke converter oscillation process by a switching process of a first switching element connected to a positive electrode via a primary winding, the ringing yoke converter is connected between a positive electrode of the DC input voltage and a control terminal of the switching element. Starting resistor, a second switching element provided between a connection point of the starting resistor and the switching element, and turning on the second switching element after the process shifts to the ringing yoke converter oscillation processing. A charging current is supplied to the first switching element by the starting resistor, and After the transition to over data oscillation process is characterized in that comprises a switch switching circuit for turning off the second switching element.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a circuit configuration of an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 3 and the conventional example are denoted by the same reference numerals, and only the differences from the conventional example will be described.

The ringing yoke converter circuit shown in FIG. 1 has the drain connected to the starting resistor R1 and the source connected to the control terminal of the switching element Q1 in the general ringing yoke converter circuit shown in FIG. The MOS-FET Q2, the positive and negative electrodes of the control winding N3, the gate of the MOS-FET Q2, and the DC input voltage V _IN are connected to detect the voltage on the negative side of the control winding N3, And a switch switching circuit 4 for turning on / off the FET. For convenience of explanation, two detection terminals for detecting the voltage of the control winding N3 among the four terminals of the switch switching circuit 4 are denoted by 4a and 4b, and a MOS
-The terminal connected to the gate of FET Q2 is 4c. The potential of the negative electrode with respect to the positive electrode of the control winding N3 is defined as Vn3.

The operation of the circuit shown in FIG. 1 will be described. However, only points different from the conventional example of FIG. 3 will be described.

When the power supply is started, the MOS-FET Q2 is turned on by a charging current from the terminal 4c of the switch switching circuit 4 to the gate of the MOS-FET Q2. As a result, a charging current flows into the gate of the switching element Q1 via the starting resistor R1 and the MOS-FET Q2, and the switching element Q1 is turned on. When the switching element Q1 turns on and the oscillation operation of the power supply starts, and the output voltage Vo rises to a desired voltage and stabilizes, the starting resistor R1 becomes unnecessary. Incidentally, the voltage Vn3 of the control winding N3 has a proportional relationship (N3 / N2 times) with the pulse voltage generated in the secondary winding N2. Therefore, the peak value of the voltage Vn3 of the control winding N3 is proportional to the output voltage Vo (N3 / N2 times), and after the power supply is started, the output voltage Vo is increased.
Rise with the rise of. When the peak value of the pulse voltage Vn3 reaches a certain voltage, the switch switching circuit 4
4a and 4b detect this, and the voltage of the terminal 4c is dropped to turn off the MOS-FET Q2.

FIG. 2 shows details of the switch switching circuit 4 of the circuit of FIG.

In FIG. 2, the switch switching circuit 4 comprises a capacitor C2 and a diode D2 inserted in series between the negative electrode and the positive electrode of the control winding N3, and resistors R3 and R4 connected in series between both terminals of the capacitor C2. And an NPN transistor Tr1 having a collector connected to the gate of the MOS-FET Q2, an emitter connected to a connection point between the capacitor C2 and the diode D2, and a base connected to a connection point between the resistors R3 and R4. , And a resistor R2 connected between the DC input voltage V _IN and the collector of the transistor Tr1. Note that the voltage of the capacitor C2 is set to Vc2 (however, based on a connection point between the anode of the diode D2 and the capacitor C2).

The operation of the circuit shown in FIG. 2 will be described.

Immediately after the start, the transistor Tr1 is off, and the impedance between the collector and the emitter is high.
Therefore, a charging current flows into the gate of the MOS-FET Q2 via the resistor R2, and the MOS-FET Q2 is turned on. Thereby, the gate of the switching element Q1 is charged via the resistor R1 and the MOS-FET Q2, and the switching element Q1 is turned on.

Here, the control winding N is connected to the capacitor C2.
A rectified and smoothed voltage Vc2 is generated from the pulse voltage Vn3 of FIG. As described above, the voltage Vc2 is equal to the output voltage N3 /
It is always proportional to N2 times. After the power supply is started, the switching element Q1 starts oscillating, and when the voltage Vc2 increases with an increase in the output voltage, the voltage of the resistor R4 also increases.
The voltage Vc2 rises, and the voltage of the resistor R4 becomes the transistor T
When the voltage reaches the base-emitter ON voltage of r1 (about 0.6 V), the transistor Tr1 turns on. The impedance between the collector and the emitter of the transistor Tr1 shifts from the previously high impedance to a low impedance, and the MOS-FE
The gate voltage of T Q2 is dropped, and the MOS-FET Q
2 turns off. Therefore, no current flows through the resistor R1, and the power consumption of the resistor R1 is eliminated.

As described above, according to the invention of the present application, the function of detecting that the power supply has shifted to the oscillating operation and suppressing unnecessary power consumption of the starting resistor can be provided only by adding a simple circuit. It is possible to provide a high-efficiency ringing-choke converter provided with the above.

[0023]

As described above, according to the present invention,
To provide a high-efficiency ringing-choke converter having a function of suppressing useless power consumption of a starting resistor after a power supply shifts to an oscillation operation by simply adding a simple circuit of a second switching element and a switching circuit. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a circuit configuration of a ringing yoke converter according to an embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating a detailed configuration of a switch switching circuit according to the embodiment of the present invention.

FIG. 3 is a circuit diagram showing a circuit configuration of a ringing chopper converter according to a conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 control circuit 2 optical coupling element 3 voltage detection circuit 4 switch switching circuit V _IN DC input voltage GND ground Vo output voltage (+) Positive output voltage terminal (−) Negative output voltage terminal T1 transformer N1 Primary winding of transformer T1 N2 Secondary winding of transformer T1 N3 Control winding of transformer T1 Q1 Switching element Q2 MOS-FET D1 Rectifying diode D2 Diode C1 Smoothing capacitor C2 Capacitor R1 Starting resistance R2, R3, R4 Resistance Tr1 NPN transistor 4a, 4b Voltage detection terminal 4c of switch switching circuit 4 Output terminal of switch switching circuit 4 Vn3 Voltage of control winding N3 Vc2 Voltage of capacitor C2

Claims (1)

[Claims] 1. A transformer having a primary winding, a secondary winding, and a control winding, and a switching process of a first switching element connected from a positive electrode of a DC input voltage terminal to a positive electrode of the transformer via the primary winding of the transformer. A ringing yoke converter that performs an oscillation process by a ringing yoke converter, comprising: a startup resistor connected between a positive electrode of the DC input voltage and a control terminal of the switching element; and a connection point between the startup resistance and the switching element. And after switching to the ringing-choke-converter oscillation process, turning on the second switching element and supplying a charging current to the first switching element by the starting resistor. After shifting to the ringing chopper converter oscillation processing, the second switching element And a switch switching circuit for turning off the switch.