Parallel balanced power quasi-resonant switching power supply circuit and control method thereof

Abstract

The invention discloses a parallel balanced power quasi-resonant switching power supply circuit and a control method thereof, the input and output ends of a first quasi-resonant circuit and a second quasi-resonant circuit both adopt a parallel structure, so that the input and output voltages are equal; a first switch tube Q78 of the first quasi-resonance circuit and a second switch tube Q9 of the second quasi-resonance circuit are controlled and driven by the same group of signals output by the input control circuit; the primary side current of the first quasi-resonance circuit and the primary side current of the second quasi-resonance circuit are consistent, two sets of output current of the first quasi-resonance circuit and the two sets of output current of the second quasi-resonance circuit are also kept consistent, and the effect of current sharing of the output current is achieved. The method comprises the following steps: performing power equalization on quasi-resonance flyback circuits of a switching power supply power converter, processing currents on two quasi-resonance power flyback switching power supply circuits, and balancing the two paths of currents of the quasi-resonance flyback switching power supply circuits, so that the total power of the two paths of quasi-resonance flyback switching power supply circuits is consistent.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supply circuits, and particularly relates to a parallel balanced power quasi-resonant switching power supply circuit and a control method thereof. Background Art

[0002] In the existing analog circuit controlled switching power supply, the traditional balanced power circuit requires two sets of independent power controls. Output current sampling is used, and two sets of independent drive signals, frequencies, and duty cycles are controlled to drive two sets of quasi-resonant switching tubes respectively, so as to adjust the balanced operation of the two sets of quasi-resonant circuits.

[0003] The method of equalizing the current in two paths mostly adopts sampling the output current, converting the output current into an equalizing bus voltage, and realizing equalizing through the bus voltage. As Figure 1 shown, an output current sampling resistor is used to sample the current, and the sampled current is input to an operational amplifier circuit for amplification. The amplified current requires many devices for the equalizing circuit, and it is also necessary to connect the equalizing bus to calibrate the output current. The required circuit structure is complex and the circuit calculation is cumbersome. Summary of the Invention

[0004] In view of this, it is necessary to provide a parallel balanced power quasi-resonant switching power supply circuit and a control method thereof that can achieve fast current sharing and have a simple structure.

[0005] A parallel balanced power quasi-resonant switching power supply circuit includes an input control circuit, a first quasi-resonant circuit, a second quasi-resonant circuit, and a mutual inductance LX5. Among them, the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the battery bus DC+, and the output circuits of the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the power output terminal V-OUT; the mutual inductance LX5 includes two independent windings with reverse mutual inductance, namely a first mutual inductance winding LX5-B and a second mutual inductance winding LX5-A; the first quasi-resonant circuit and the second quasi-resonant circuit are respectively connected to the two independent windings with reverse mutual inductance of the mutual inductance LX5.

[0006] Preferably, the first quasi-resonant circuit includes a first switching tube Q78 and a first transformer T3. The primary winding T3-B of the first transformer T3 and the first switching tube Q78 are respectively connected to the same-name end and the different-name end of the first mutual inductance winding LX5-B; the second quasi-resonant circuit includes a second switching tube Q9 and a second transformer T4. The primary winding T4-B of the second transformer T4 and the second switching tube Q9 are respectively connected to the same-name end and the different-name end of the second mutual inductance winding LX5-A.

[0007] Preferably, the primary winding T3-B of the first transformer T3 is connected to the battery bus DC+ through the eighth diode D8 and the first input RC filter circuit; the drain of the first switching transistor Q78 is connected to the non-inverting terminal of the first mutual inductance winding LX5-B, the source of the first switching transistor Q78 is grounded, and the gate of the first switching transistor Q78 is connected to the input control circuit; the inverting terminal of the first mutual inductance winding LX5-B is connected to the non-inverting terminal of the primary winding T3-B of the first transformer T3; The secondary winding T3-A of the first transformer T3 is connected to the power output terminal V-OUT through the thirty-sixth diode D36 and the first output capacitor C183.

[0008] Preferably, the primary winding T4-B of the second transformer T4 is connected to the battery bus DC+ through the fifteenth diode D15 and the second input RC filter circuit; the drain of the second switching transistor Q9 is connected to the non-inverting terminal of the second mutual inductance winding LX5-A, the source of the second switching transistor Q9 is grounded, and the gate of the second switching transistor Q9 is connected to the input control circuit; the inverting terminal of the second mutual inductance winding LX5-A is connected to the non-inverting terminal of the primary winding T4-B of the second transformer T4; The secondary winding T4-A of the second transformer T4 is connected to the power output terminal V-OUT through the twenty-first diode D21 and the second output capacitor C50.

[0009] Preferably, the first mutual inductance winding LX5-B and the second mutual inductance winding LX5-A are wound in a coil reverse winding manner, so as to generate a reverse magnetic field by controlling the current direction, and reduce the total mutual inductance value.

[0010] And, a control method for a parallel balanced power quasi-resonant switching power supply circuit, which is used to achieve power balance of two quasi-resonant flyback switching power supply circuits through the parallel balanced power quasi-resonant switching power supply circuit as described above. The specific steps include: Step 1, connect the input ends of the first quasi-resonant circuit and the second quasi-resonant circuit in parallel to the battery bus DC+, and connect the output ends of the output circuits in parallel to the output terminal V-OUT; Step 2, the power current of the first quasi-resonant circuit passes through the mutual exclusion inductor in the positive direction, and the power current of the second quasi-resonant circuit passes through the mutual exclusion inductor in the reverse direction, and the currents of the two quasi-resonant circuits pass through the mutual exclusion inductor in opposite directions; Step 3, when the currents of the two quasi-resonant circuits pass through the mutual exclusion inductor, the impedance is 0 when the currents in the two directions are the same; Step 4: When the currents passing through the mutual inductance of the two quasi-resonant circuits are inconsistent, the impedance of the mutual inductance in the current direction of the quasi-resonant circuit with the larger current increases, so the current decreases; the impedance of the mutual inductance in the current direction of the other quasi-resonant circuit with the smaller current remains unchanged, and the current remains unchanged; thus, the currents of the two quasi-resonant circuits are made consistent.

[0011] Preferably, before the step of connecting the input ends of the first quasi-resonant circuit and the second quasi-resonant circuit in parallel to the battery bus DC+ and connecting the output ends of the output circuits in parallel to the output end V - OUT in the step 1, the following steps are further included: Both the input and output ends of the first quasi-resonant circuit and the second quasi-resonant circuit adopt a parallel structure to make the input and output voltages equal; The first switching tube Q78 of the first quasi-resonant circuit and the second switching tube Q9 of the second quasi-resonant circuit are both controlled and driven by the input control circuit; The primary side currents of the first quasi-resonant circuit and the second quasi-resonant circuit are kept consistent, so that the two sets of output currents of the first quasi-resonant circuit and the second quasi-resonant circuit are also kept consistent.

[0012] In the above parallel balanced power quasi-resonant switch power supply circuit and its control method, both the input and output ends of the first quasi-resonant circuit and the second quasi-resonant circuit adopt a parallel structure to make the input and output voltages equal; the first switching tube Q78 of the first quasi-resonant circuit and the second switching tube Q9 of the second quasi-resonant circuit are both controlled and driven by the same set of signals output by the input control circuit; the primary side currents of the first quasi-resonant circuit and the second quasi-resonant circuit are consistent, then the two sets of output currents of the first quasi-resonant circuit and the second quasi-resonant circuit are also kept consistent, achieving the effect of output current equalization. The power of the switch power supply power converter quasi-resonant flyback circuit is balanced, the currents on the two quasi-resonant power flyback switch power supply loops are processed, the two paths of currents of the quasi-resonant flyback switch power supply circuit are balanced, and the total power of the two paths of quasi-resonant flyback switch power supply circuits is made consistent. The circuit structure of the present invention is simple, easy to implement, low in cost, and convenient for popularization. Description of the Drawings

[0013] Figure 1 is an analog circuit controlled switch power supply circuit of the prior art.

[0014] Figure 2 is a schematic circuit structure diagram of the parallel balanced power quasi-resonant switch power supply circuit of the embodiment of the present invention. Detailed Embodiment

[0015] Taking the parallel balanced power quasi-resonant switch power supply circuit and its control method as an example in this embodiment, the present invention will be described in detail below in combination with specific embodiments and drawings.

[0016] Please refer to Figure 2, showing a parallel balanced power quasi-resonant switching power supply circuit provided by an embodiment of the present invention, including an input control circuit, a first quasi-resonant circuit, a second quasi-resonant circuit, and a mutual exclusion inductor LX5. Among them, the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the battery bus DC+, and the output circuits of the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the power output terminal V-OUT; the mutual exclusion inductor LX5 includes two independent windings with reverse mutual inductance, namely the first mutual inductance winding LX5-B and the second mutual inductance winding LX5-A; the first quasi-resonant circuit and the second quasi-resonant circuit are respectively connected to the two independent windings with reverse mutual inductance of the mutual exclusion inductor LX5.

[0017] Preferably, the first quasi-resonant circuit includes a first switching tube Q78 and a first transformer T3. The primary winding T3-B of the first transformer T3 and the first switching tube Q78 are respectively connected to the same-named end and the different-named end of the first mutual inductance winding LX5-B; the second quasi-resonant circuit includes a second switching tube Q9 and a second transformer T4. The primary winding T4-B of the second transformer T4 and the second switching tube Q9 are respectively connected to the same-named end and the different-named end of the second mutual inductance winding LX5-A.

[0018] Preferably, the primary winding T3-B of the first transformer T3 is connected to the battery bus DC+ through an eighth diode D8 and a first input RC filtering circuit; the drain of the first switching tube Q78 is connected to the different-named end of the first mutual inductance winding LX5-B, the source of the first switching tube Q78 is grounded, and the gate of the first switching tube Q78 is connected to the input control circuit; the same-named end of the first mutual inductance winding LX5-B is connected to the different-named end of the primary winding T3-B of the first transformer T3; The secondary winding T3-A of the first transformer T3 is connected to the power output terminal V-OUT through a thirty-sixth diode D36 and a first output capacitor C183.

[0019] Specifically, the first input RC filtering circuit includes a series-connected four hundred and fifty-second resistor R452 and a four hundred and fifty-third resistor R453, and a parallel-connected three hundred and thirty-first capacitor C331.

[0020] Preferably, the primary winding T4-B of the second transformer T4 is connected to the battery bus DC+ through a fifteenth diode D15 and a second input RC filtering circuit; the drain of the second switching tube Q9 is connected to the different-named end of the second mutual inductance winding LX5-A, the source of the second switching tube Q9 is grounded, and the gate of the second switching tube Q9 is connected to the input control circuit; the same-named end of the second mutual inductance winding LX5-A is connected to the different-named end of the primary winding T4-B of the second transformer T4; The secondary winding T4 -A of the second transformer T4 is connected to the power output terminal V-OUT via the twenty-first diode D21 and the second output capacitor C50 .

[0021] Specifically, the second input RC filter circuit includes a one-hundred-eighty-first resistor R181 and a one-hundred-eighty-third resistor R183 connected in series, and a one-hundred-eighth capacitor C108 connected in parallel.

[0022] Specifically, the power current of the second quasi-resonant circuit passes through the mutual exclusion inductor LX5 in the forward direction, and the power current of the first quasi-resonant circuit passes through the mutual exclusion inductor LX5 in the reverse direction.

[0023] The high potential terminal of the primary winding T4-B of the second transformer T4 of the second quasi-resonant circuit is connected to the battery bus DC+, and the low potential terminal is connected to the input terminal of pin 1 of the mutual exclusion inductor LX5, and is output to the drain of the second switch tube Q9 through pin 2 of the mutual exclusion inductor LX5. The source of the second switch tube Q9 under switch control returns to the ground terminal GND of the battery bus DC+.

[0024] The high potential terminal of the primary winding T3-B of the first transformer T3 of the first quasi-resonant circuit is connected to the battery bus DC+, and the low potential terminal is connected to the 4-pin input terminal of the mutual exclusion inductor LX5, and is output to the drain of the first switch tube Q78 through the 3-pin of the mutual exclusion inductor LX5. The source of the first switch tube Q78 under the control of the switch returns to the ground terminal GND of the battery bus DC+.

[0025] The loop currents of the two quasi-resonant circuits all pass through the mutually exclusive inductance, and the currents of the two quasi-resonant circuits pass through the mutually exclusive inductance from two opposite directions.

[0026] When the current on the quasi-resonant circuit is consistent when passing through the mutually exclusive inductor, the impedance is 0. When the current in one of the quasi-resonant circuits is too large, the current in the other quasi-resonant circuit is too small. The impedance formed on the inductor of the quasi-resonant circuit with large current becomes larger, hindering the current from passing through. When the current in the other quasi-resonant circuit is too small, the impedance remains unchanged, and the power current flows normally, thereby making the currents of the two quasi-resonant circuits consistent.

[0027] The power currents of the two quasi-resonant circuits flow normally, thereby making the currents of the two quasi-resonant circuits consistent.

[0028] Since the output sampling of the two quasi-resonant circuits is the same loop, the driving signal of the input control circuit uses the same set of signals, and the input and output of the two quasi-resonant circuits are parallel structures, the input voltage and the output voltage are equal. When the primary currents of the two quasi-resonant circuits are consistent, the two output currents are also consistent, thereby achieving an output current equalization effect.

[0029] Preferably, the first mutual inductance winding LX5-B and the second mutual inductance winding LX5-A are wound in a reverse coil winding manner to generate a reverse magnetic field by controlling the current direction, thereby reducing the total mutual inductance value.

[0030] In addition, a control method for a parallel balanced power quasi-resonant switching power supply circuit is used to achieve power balance of two quasi-resonant flyback switching power supply circuits through the parallel balanced power quasi-resonant switching power supply circuit as described above. The specific steps include: Step S10: The input and output terminals of the first quasi-resonant circuit and the second quasi-resonant circuit both adopt a parallel structure to make the input and output voltages equal; The first switching transistor Q78 of the first quasi-resonant circuit and the second switching transistor Q9 of the second quasi-resonant circuit are both controlled and driven by an input control circuit; If the primary side currents of the first quasi-resonant circuit and the second quasi-resonant circuit are the same, then the two sets of output currents of the first quasi-resonant circuit and the second quasi-resonant circuit are also the same.

[0031] Step S20: The input terminals of the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the battery bus DC+, and the output terminals of the output circuits are connected in parallel to the output terminal V-OUT.

[0032] Step S30: The power current of the first quasi-resonant circuit passes through the mutual exclusion inductor in the positive direction, and the power current of the second quasi-resonant circuit passes through the mutual exclusion inductor in the reverse direction. The currents of the two quasi-resonant circuits pass through the mutual exclusion inductor in opposite directions.

[0033] Specifically, the power current of the first quasi-resonant circuit passes through the mutual exclusion inductor in the positive direction, outputs to the drain of the first switching transistor Q78, and returns to the ground terminal GND through the source of the first switching transistor Q78 controlled by the input control circuit; the power current of the second quasi-resonant circuit passes through the mutual exclusion inductor in the reverse direction, outputs to the drain of the second switching transistor Q9, and returns to the ground terminal GND through the source of the first switching transistor Q78 controlled by the input control circuit; Step S40: When the currents of the two quasi-resonant circuits pass through the mutual exclusion inductor, if the currents in the two directions are the same, the impedance is 0.

[0034] Step S50: When the currents of the two quasi-resonant circuits passing through the mutual exclusion inductor are not the same, the impedance of the mutual exclusion inductor in the current direction of the quasi-resonant circuit with a larger current becomes larger, and the current decreases; the impedance of the mutual exclusion inductor in the current direction of the other quasi-resonant circuit with a smaller current remains unchanged, and the current remains unchanged; thus, the currents of the two quasi-resonant circuits are made the same.

[0035] Specifically, when the current of the first quasi-resonant circuit is too large and the current of the second quasi-resonant circuit is too small, the large current of the first quasi-resonant circuit causes the impedance formed on the mutual inductance to increase, hindering the current from passing through; the small current of the second quasi-resonant circuit results in an unchanged impedance on the mutual inductance, allowing the current to flow normally, thus making the currents of the two quasi-resonant circuits consistent.

[0036] In this embodiment, the input voltages of the two quasi-resonant circuits are the same, and the two output circuits adopt a parallel loop output. The input control circuit controls the two quasi-resonant circuits simultaneously, making the frequencies and duty cycles of their drive signals the same, and simultaneously driving the first switch tube Q78 and the second switch tube Q9 so that the two quasi-resonant circuits both operate normally in an equilibrium state.

[0037] When the currents of the two quasi-resonant circuits are inconsistent, the mutual inductance LX5 adjusts the circuit impedance to keep the currents of the two quasi-resonant circuits consistent.

[0038] In the above parallel balanced power quasi-resonant switching power supply circuit and its control method, the input and output ends of the first quasi-resonant circuit and the second quasi-resonant circuit both adopt a parallel structure, making the input and output voltages equal; the first switch tube Q78 of the first quasi-resonant circuit and the second switch tube Q9 of the second quasi-resonant circuit are both controlled and driven by the same set of signals output by the input control circuit; if the primary currents of the first quasi-resonant circuit and the second quasi-resonant circuit are consistent, then the two sets of output currents of the first quasi-resonant circuit and the second quasi-resonant circuit are also consistent, achieving the effect of output current equalization. Power balance is performed on the quasi-resonant flyback circuit of the switching power supply power converter, the currents on the two quasi-resonant power flyback switching power supply loops are processed, and the two currents of the quasi-resonant flyback switching power supply circuit are balanced, making the total power of the two quasi-resonant flyback switching power supply circuits consistent. The circuit structure of the present invention is simple, easy to implement, low in cost, and convenient for popularization.

[0039] It should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A parallel balanced power quasi-resonant switching power supply circuit, characterized in that: It includes an input control circuit, a first quasi-resonant circuit, a second quasi-resonant circuit and a mutually exclusive inductor LX5, wherein the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the battery bus DC+, and the output circuits of the first quasi-resonant circuit and the second quasi-resonant circuit are connected in parallel to the power output terminal V-OUT; the mutually exclusive inductor LX5 includes two independent windings with reverse mutual inductance, namely a first mutual inductance winding LX5-B and a second mutual inductance winding LX5-A; the first quasi-resonant circuit and the second quasi-resonant circuit are respectively connected to the two independent windings with reverse mutual inductance of the mutually exclusive inductor LX5.

2. The parallel balanced power quasi-resonant switching power supply circuit according to claim 1, characterized in that: The first quasi-resonant circuit includes a first switch tube Q78 and a first transformer T3, the primary winding T3-B of the first transformer T3 and the first switch tube Q78 are respectively connected to the same-name end and the opposite-name end of the first mutual inductance winding LX5-B; the second quasi-resonant circuit includes a second switch tube Q9 and a second transformer T4, the primary winding T4-B of the second transformer T4 and the second switch tube Q9 are respectively connected to the same-name end and the opposite-name end of the second mutual inductance winding LX5-A.

3. The parallel balanced power quasi-resonant switching power supply circuit according to claim 2, characterized in that: The primary winding T3-B of the first transformer T3 is connected to the battery bus DC+ through the eighth diode D8 and the first input RC filter circuit; the drain of the first switch tube Q78 is connected to the opposite end of the first mutual inductance winding LX5-B, the source of the first switch tube Q78 is grounded, and the gate of the first switch tube Q78 is connected to the input control circuit; the same end of the first mutual inductance winding LX5-B is connected to the opposite end of the primary winding T3-B of the first transformer T3; The secondary winding T3 -A of the first transformer T3 is connected to the power output terminal V-OUT via a thirty-sixth diode D36 and a first output capacitor C183 .

4. The parallel balanced power quasi-resonant switching power supply circuit according to claim 2, characterized in that: The primary winding T4-B of the second transformer T4 is connected to the battery bus DC+ through the fifteenth diode D15 and the second input RC filter circuit; the drain of the second switch tube Q9 is connected to the opposite end of the second mutual inductance winding LX5-A, the source of the second switch tube Q9 is grounded, and the gate of the second switch tube Q9 is connected to the input control circuit; the same end of the second mutual inductance winding LX5-A is connected to the opposite end of the primary winding T4-B of the second transformer T4; The secondary winding T4 -A of the second transformer T4 is connected to the power output terminal V-OUT via the twenty-first diode D21 and the second output capacitor C50 .

5. The parallel balanced power quasi-resonant switching power supply circuit according to claim 1, characterized in that: The first mutual inductance winding LX5-B and the second mutual inductance winding LX5-A are wound in reverse order, so that a reverse magnetic field is generated by current direction control, thereby reducing the total mutual inductance value.

6. A control method for a parallel balanced power quasi-resonant switching power supply circuit, used to achieve power balancing of two quasi-resonant flyback switching power supply circuits through the parallel balanced power quasi-resonant switching power supply circuit as described in any one of claims 1 to 5, characterized in that: The specific steps include: Step 1, connecting the input ends of the first quasi-resonant circuit and the second quasi-resonant circuit in parallel to the battery bus DC+, and connecting the output end of the output circuit in parallel to the output end V-OUT; Step 2: the power current of the first quasi-resonant circuit passes through the mutually exclusive inductor in a forward direction, and the power current of the second quasi-resonant circuit passes through the mutually exclusive inductor in a reverse direction, and the currents of the two quasi-resonant circuits pass through the mutually exclusive inductor in opposite directions; Step 3: When the currents of the two quasi-resonant circuits pass through the mutually exclusive inductors, the currents in the two directions are consistent and the impedance is 0; Step 4, when the currents passing through the mutually exclusive inductors of the two quasi-resonant circuits are inconsistent, the impedance of the mutually exclusive inductor in the current direction of the quasi-resonant circuit with a larger current increases, and the current decreases; the impedance of the mutually exclusive inductor in the current direction of the other quasi-resonant circuit with a smaller current remains unchanged, and the current remains unchanged; the currents of the two quasi-resonant circuits are made consistent.

7. The control method of the parallel balanced power quasi-resonant switching power supply circuit according to claim 6, characterized in that: Before the step of connecting the input ends of the first quasi-resonant circuit and the second quasi-resonant circuit in parallel to the battery bus DC+ and the output end of the output circuit in parallel to the output end V-OUT in step 1, the following steps are also included: The input and output ends of the first quasi-resonant circuit and the second quasi-resonant circuit are both connected in parallel to make the input and output voltages equal; The first switch tube Q78 of the first quasi-resonant circuit and the second switch tube Q9 of the second quasi-resonant circuit are both controlled and driven by the input control circuit; The primary currents of the first quasi-resonant circuit and the second quasi-resonant circuit are kept consistent, so that the two groups of output currents of the first quasi-resonant circuit and the second quasi-resonant circuit are also kept consistent.

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