CN214480288U - Magnetic isolation driving circuit - Google Patents

Abstract

The utility model provides a magnetic isolation driving circuit, which can maintain the original driving voltage while providing high duty ratio, comprising a transformer T1, a switch tube Q1, a switch tube Q2, a diode D1, a diode D2 and a resistor R1; a primary winding of the transformer T1, a pulse signal output circuit and a switching tube Q1 form an input side loop, and a secondary winding of the transformer T1, a switching tube Q2, a diode D1, a diode D2, a resistor R1 and a power loop main switching tube Q3 form an output side loop; when the duty ratio is increased and the reset voltage is increased, the diode D2 can cut off the reverse reset voltage to protect the gate-source electrode of the main switch tube Q3 of the power loop from being influenced, and meanwhile, the problem that the main switch tube Q3 of the power loop is switched on by mistake due to loss of the duty ratio is solved; the circuit is simple and reliable, and the cost is low.

Description

Magnetic isolation driving circuit

Technical Field

The utility model relates to a drive circuit technical field, in particular to drive circuit is kept apart to magnetism.

Background

The magnetic isolation driving circuit is widely applied to driving a suspended ground switch tube and is used for driving the main switch tube to be switched on and off. Recent advances in many industries have placed many new demands on the design of switching power supplies. Such as higher input voltage, wider input range. Particularly, in some emerging industries, such as the photovoltaic new energy industry, the demand of the switching power supply with high input voltage and wide input range is considerable. When designing a switching power supply with a wide input, the variation range of the duty ratio of the switching power supply means the variation range of the input voltage. The size of the duty cycle variation directly determines the input range and the load capacity of the switching power supply.

A conventional magnetic isolation driving circuit is shown in fig. 1, where C1 is an input side dc blocking capacitor, transformer T1 is a magnetic isolation transformer, and Q3 is a main switch tube of a power circuit.

The problems in the prior art are as follows: when the duty ratio of the pulse signal is increased, the driving voltage of the switching tube Q3 is continuously reduced, and when the duty ratio is increased to a certain value, the driving voltage of the switching tube Q3 is lower than a conduction threshold value, which will cause that the switching tube Q3 cannot be normally conducted, so that the power supply cannot normally work.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention provides a magnetic isolation driving circuit, which can maintain the original driving voltage while providing a high duty ratio.

The utility model discloses a realize through following technical scheme:

a magnetic isolation driving circuit is used for driving the on-off of a power loop main switch tube Q3 and is characterized in that: the power supply comprises a transformer T1, a switching tube Q1, a switching tube Q2, a diode D1, a diode D2 and a resistor R1; the dotted terminal of the primary winding of the transformer T1 is connected with the positive terminal of the pulse signal output circuit and the gate of the switching tube Q1, the synonym terminal of the primary winding of the transformer T1 is connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with the negative terminal of the pulse signal output circuit, the dotted terminal of the secondary winding of the transformer T1 is connected with one terminal of a resistor R1 and the anode of a diode D2, the cathode of the diode D2 is connected with the emitter of a switching tube Q2 and the gate of a main power circuit switching tube Q3, the other terminal of the resistor R1 is connected with the cathode of the diode D1 and the base of the switching tube Q2, and the synonym terminal of the secondary winding of the transformer T1 is connected with the anode of a diode D1, the collector of the switching tube Q2 and the source of the main power circuit switching tube Q3.

A magnetic isolation driving circuit is used for driving the on-off of a power loop main switch tube Q3 and is characterized in that: the power supply comprises a transformer T1, a switching tube Q1, a switching tube Q2, a diode D1, a diode D2 and a resistor R1;

the dotted terminal of the primary winding of the transformer T1 is connected with the positive terminal of an external power supply, the dotted terminal of the primary winding of the transformer T1 is connected with the drain of a switching tube Q1, the gate of the switching tube Q1 is connected with the positive terminal of a pulse signal output circuit, the source of the switching tube Q1 is connected with the negative terminal of the pulse signal output circuit, the dotted terminal of the secondary winding of the transformer T1 is connected with one end of a resistor R1 and the anode of a diode D2, the cathode of the diode D2 is connected with the emitter of a switching tube Q2 and the gate of a main switching tube Q3 of a power loop, the other end of a resistor R1 is connected with the cathode of the diode D1 and the base of the switching tube Q2, and the dotted terminal of the secondary winding of the transformer T1 is connected with the anode of the diode D1, the collector of the switching tube Q2 and the source of the main switching tube Q3 of the power loop.

Compared with the prior art, the utility model discloses following beneficial effect has:

1. when the duty ratio is increased, the amplitude of the driving voltage of the main switching tube Q3 of the power circuit is not influenced by the duty ratio;

2. under the conditions that the voltage resistance of the switching tube Q1 and the diode D2 is high enough and the resistance of the resistor R1 is large enough, the duty ratio of the magnetic isolation driving circuit of the utility model can be infinitely close to 1;

3. the problem that the power loop main switching tube Q3 is switched on by mistake due to loss of the duty ratio is solved; the circuit is simple and reliable, and the cost is low.

Drawings

FIG. 1 is a circuit schematic of a prior art magnetically isolated drive circuit;

fig. 2 is a schematic circuit diagram of a first embodiment of the magnetic isolation driving circuit of the present invention;

fig. 3 is a schematic circuit diagram of a second embodiment of the magnetic isolation driving circuit of the present invention.

Detailed Description

In order to make the present invention more clearly understood, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

First embodiment

As shown in fig. 2, a magnetic isolation driving circuit includes a transformer T1, a switching tube Q1, a switching tube Q2, a diode D1, a diode D2 and a resistor R1; a primary winding of the transformer T1, a pulse signal output circuit and a switching tube Q1 form an input side loop, and a secondary winding of the transformer T1, a switching tube Q2, a switching tube Q3, a diode D1, a diode D2 and a resistor R1 form an output side loop;

the specific connection relationship of the circuit is as follows: the dotted terminal of the primary winding of the transformer T1 is connected with the positive terminal of the pulse signal output circuit and the gate of the switching tube Q1, the synonym terminal of the primary winding of the transformer T1 is connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with the negative terminal of the pulse signal output circuit, the dotted terminal of the secondary winding of the transformer T1 is connected with one terminal of a resistor R1 and the anode of a diode D2, the cathode of the diode D2 is connected with the emitter of a switching tube Q2 and the gate of a main power circuit switching tube Q3, the other terminal of the resistor R1 is connected with the cathode of the diode D1 and the base of the switching tube Q2, and the synonym terminal of the secondary winding of the transformer T1 is connected with the anode of a diode D1, the collector of the switching tube Q2 and the source of the main power circuit switching tube Q3.

The switching tube Q2 is a PNP triode, the transformer T1 is an isolation driving transformer, and the diode D1 and the resistor R1 form a reset circuit of the isolation driving transformer T1.

The working principle of the embodiment is as follows:

when the output of the pulse signal output circuit is at a high level, the switching tube Q1 is switched on, the voltage amplitude of the pulse signal is completely added to the primary winding of the isolation driving transformer T1, an induced voltage with an equal proportional amplitude is generated at the secondary winding of the isolation driving transformer T1, and the induced voltage is added to the gate-source electrode of the main switching tube Q3 of the power circuit through the diode D2, so that the switching tube Q3 is switched on.

When the output of the pulse signal output circuit is low level, the switching tube Q1 is cut off, the reverse reset voltage of the isolation driving transformer T1 is added to the resistor R1 through the diode D1, the reset voltage and the reset time of the isolation driving transformer T1 are influenced by the resistance value, the larger the resistance value is, the larger the reset voltage is, the shorter the reset time is, the voltage at the same name side of the secondary winding of the isolation driving transformer T1 is negative during reset, the voltage at the different name side is positive, and the diode D2 is cut off and reversely biased, so that the gate-source electrode of the main switching tube Q3 of the power circuit is protected from being broken down by the reset voltage.

During the reset period of the isolation transformer T1, since the diode D2 is subjected to reverse bias voltage, the base-emitter PN junction of the PNP transistor Q2 is forward biased through the resistor R1, the PNP transistor Q2 is turned on, and the junction capacitor of the power circuit main switch Q3 is discharged through the PNP transistor Q2.

Keep apart driving transformer reset time interior switch tube Q1 and diode D2 bear reverse bias reset voltage, theoretically switch tube Q1 and diode D2 withstand voltage under the enough big condition of resistance R1 resistance, the utility model discloses keep apart drive circuit's duty ratio can be unlimited and be close to 1.

When the duty ratio is increased and the reset voltage is increased, the diode D2 can cut off the reverse reset voltage to protect the gate-source electrode of the main switch tube Q3 of the power circuit from being influenced, and because the PN junction of the switch tube Q2 is forward biased in the reset time of the isolation driving transformer T1, the switch tube Q2 is conducted, and the junction capacitance discharge of the main switch tube Q3 of the power circuit is completed.

Second embodiment

As shown in fig. 3, a schematic circuit diagram of the magnetic isolation driving circuit of the present embodiment is shown, and the present embodiment is different from the first embodiment in that: the dotted terminal of the primary winding of the transformer T1 is connected with the external power supply positive terminal, and other electrical connection relations are unchanged.

The working principle of this embodiment is the same as that of the first embodiment, and is not described herein again.

The embodiments of the present invention are not limited to the above, and according to the above-mentioned contents of the present invention, the common technical knowledge and the conventional means in the field are utilized, without departing from the basic technical idea of the present invention, the specific implementation circuit of the present invention can also make other modifications, replacements or changes in various forms, all falling within the scope of the present invention.

Claims (2)

1. A magnetic isolation driving circuit is used for driving the on-off of a power loop main switch tube Q3 and is characterized in that: the power supply comprises a transformer T1, a switching tube Q1, a switching tube Q2, a diode D1, a diode D2 and a resistor R1; the dotted terminal of the primary winding of the transformer T1 is connected with the positive terminal of the pulse signal output circuit and the gate of the switching tube Q1, the synonym terminal of the primary winding of the transformer T1 is connected with the drain of the switching tube Q1, the source of the switching tube Q1 is connected with the negative terminal of the pulse signal output circuit, the dotted terminal of the secondary winding of the transformer T1 is connected with one terminal of a resistor R1 and the anode of a diode D2, the cathode of the diode D2 is connected with the emitter of a switching tube Q2 and the gate of a main power circuit switching tube Q3, the other terminal of the resistor R1 is connected with the cathode of the diode D1 and the base of the switching tube Q2, and the synonym terminal of the secondary winding of the transformer T1 is connected with the anode of a diode D1, the collector of the switching tube Q2 and the source of the main power circuit switching tube Q3.

2. A magnetic isolation driving circuit is used for driving the on-off of a power loop main switch tube Q3 and is characterized in that: the power supply comprises a transformer T1, a switching tube Q1, a switching tube Q2, a diode D1, a diode D2 and a resistor R1;

the dotted terminal of the primary winding of the transformer T1 is connected with the positive terminal of an external power supply, the dotted terminal of the primary winding of the transformer T1 is connected with the drain of a switching tube Q1, the gate of the switching tube Q1 is connected with the positive terminal of a pulse signal output circuit, the source of the switching tube Q1 is connected with the negative terminal of the pulse signal output circuit, the dotted terminal of the secondary winding of the transformer T1 is connected with one end of a resistor R1 and the anode of a diode D2, the cathode of the diode D2 is connected with the emitter of a switching tube Q2 and the gate of a main switching tube Q3 of a power loop, the other end of a resistor R1 is connected with the cathode of the diode D1 and the base of the switching tube Q2, and the dotted terminal of the secondary winding of the transformer T1 is connected with the anode of the diode D1, the collector of the switching tube Q2 and the source of the main switching tube Q3 of the power loop.

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