BUCK type switching power supply with two-way isolated output

Abstract

The utility model relates to a BUCK type switching power supply with double-path isolation output, which comprises a PWM control circuit, a power conversion circuit, a main output circuit, an isolation auxiliary circuit and a chip power supply feedback circuit, and is characterized in that the PWM control circuit is composed of an input power supply, a capacitor C3 and a control chip U1; the power conversion circuit is composed of a pin 8 of the output end of the control chip U1, a capacitor D4 and coupling inductors T1 and T2. The main output circuit is composed of a coupling inductor T2, a capacitor C5 and a capacitor C6. The number of the isolation auxiliary circuits is two, one circuit is composed of a coupling inductor T1, a diode D1 and a capacitor C1, the other circuit is composed of a coupling inductor T2, a diode D2 and a capacitor C2, and the chip power supply feedback circuit is composed of a diode D3 and a capacitor C4. According to the power supply circuit, the coupling inductors are adopted to replace a traditional high-frequency transformer, different numbers of coupling inductors are connected in series and in parallel, multi-path isolation and different voltage output can be achieved, and the power supply circuit has the advantages of being few in peripheral elements, small in size and low in cost.

Description

Technical Field

[0001] The utility model belongs to the technical field of switching power supplies, and in particular relates to a BUCK type switching power supply with dual-path isolation outputs. Background Art

[0002] Usually in the low-voltage electric field, such as electric vehicle controllers, instruments, battery BMS and power tools, it is necessary to convert relatively high voltage into low voltage electricity to power the control circuit and require isolation, usually 48-72V to 12V or 5V. Generally, a small-power flyback power supply or a finished DC module is used. The former has the disadvantages of complex circuits and high costs; the latter is small in size but more expensive. Therefore, there is currently no ideal solution for applications with high volume requirements and cost sensitivity. Utility Model Content

[0003] The purpose of the utility model is to solve the above problems and provide a BUCK type switching power supply with dual-channel isolated output, which adopts coupled inductors instead of traditional high-frequency transformers to achieve dual-channel isolated output, and can achieve multi-channel isolation and different voltage outputs by using different numbers of coupled inductors.

[0004] To achieve the above object, the utility model provides the following technical solutions: a BUCK type switching power supply with dual-channel isolated output, including a PWM control circuit, a power conversion circuit, a main output circuit, an isolation auxiliary circuit and a chip power supply feedback circuit, wherein the PWM control circuit is composed of an input power supply, a capacitor C3 and a control chip U1, wherein the input power supply is connected to the 5th and 6th pins of the control chip U1 as input via the capacitor C3, and the 8th pin of the control chip U1 is used as an output terminal;

[0005] The power conversion circuit is composed of the output terminal 8-pin of the control chip U1, the capacitor D4, and the coupled inductors T1 and T2. The 8-pin of the control chip U1 is connected to the cathode of the diode D4 and the 1-pin of the coupled inductor T1. The anode of the diode D4 is connected to GND. The 3-pin of the coupled inductor T1 is connected to the 1-pin of the coupled inductor T2.

[0006] The main output circuit is composed of a coupling inductor T2, a capacitor C5 and a capacitor C6. The 3rd pin of the coupling inductor T2 is connected to the positive electrodes of the capacitors C5 and C6 as a non-isolated output VCC1, and the negative electrodes of the capacitors C5 and C6 are connected to GND as the negative electrode of the non-isolated output.

[0007] The isolation auxiliary circuit is provided with two circuits, one of which is composed of a coupling inductor T1, a diode D1, and a capacitor C1, wherein the 4th pin of the coupling inductor T2 is connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is connected to one end of the capacitor C1 as the positive electrode VCC2, and the 2nd pin of the coupling inductor T1 is connected to the other end of the capacitor C2 as the negative electrode GND2; the other circuit is composed of a coupling inductor T2, a diode D2, and a capacitor C2, wherein the 4th pin of the coupling inductor T2 is connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is connected to one end of the capacitor C2 as the positive electrode VCC3, and the 2nd pin of the coupling inductor T2 is connected to the other end of the capacitor C2 as the negative electrode GND3.

[0008] Further: the chip power supply feedback circuit is composed of a diode D3 and a capacitor C4, the positive electrode of the diode D3 is connected to VCC1, and the negative electrode is divided into two paths, one is connected to pin 1 of the control chip U1, and the other is connected to the capacitor C4, and the other end of the capacitor C4 is connected to pin 8 of the control chip U1.

[0009] Furthermore: the coupled inductor T1 is connected in series with the coupled inductor T2, and the pin 3 of the coupled inductor T1 is connected to the pin 1 of the coupled inductor T2.

[0010] Further: the control chip U1 is a PWM control chip.

[0011] Compared with the prior art, the beneficial effects of the utility model are:

[0012] This switching power supply is based on the BUCK topology. The circuit uses coupled inductors instead of traditional high-frequency transformers to achieve dual-channel isolated output. In addition, the topology itself has one non-isolated channel, so this power supply circuit has a total of three outputs; it is highly flexible and uses different numbers of coupled inductors connected in series and parallel to achieve multi-channel isolation and different voltage outputs. This circuit is composed of conventional components, and the control chip uses a PWM control chip, which has the characteristics of few peripheral components, small size, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only for more clearly illustrating the embodiments of the utility model or the technical solutions in the prior art. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 It is the overall circuit diagram of the utility model;

[0015] Figure 2 This is the application circuit diagram of the utility model. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand and implement the technical solution of the utility model, the utility model is further described below in conjunction with specific embodiments. However, the embodiments are only used as an explanation of the utility model and are not intended to limit the utility model.

[0017] like Figure 1 The BUCK type switching power supply with dual-channel isolated output includes a PWM control circuit, a power conversion circuit, a main output circuit, an isolation auxiliary circuit and a chip power supply feedback circuit, wherein the PWM control circuit is composed of an input power supply connected to pins 5 and 6 of the control chip U1 via a capacitor C3 as an input, and pin 8 of the control chip U1 as an output terminal.

[0018] The power conversion circuit is composed of the 8th pin of the control chip U1 connected to the cathode of the diode D4 and the 1st pin of the coupling inductor T1, the anode of the diode D4 connected to GND, and the 3rd pin of the coupling inductor T1 connected to the 1st pin of the coupling inductor T2.

[0019] The main output circuit is composed of the 3rd pin of the coupling inductor T2 connected to the positive electrodes of the capacitors C5 and C6 as the non-isolated output VCC1, and the negative electrodes of the capacitors C5 and C6 connected to GND as the negative electrode of the non-isolated output.

[0020] The isolation auxiliary circuit is provided with two circuits, one of which is composed of a coupling inductor T1, a diode D1, and a capacitor C1, wherein the 4th pin of the coupling inductor T2 is connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is connected to one end of the capacitor C1 as the positive electrode VCC2, and the 2nd pin of the coupling inductor T1 is connected to the other end of the capacitor C2 as the negative electrode GND2; the other circuit is composed of a coupling inductor T2, a diode D2, and a capacitor C2, wherein the 4th pin of the coupling inductor T2 is connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is connected to one end of the capacitor C2 as the positive electrode VCC3, and the 2nd pin of the coupling inductor T2 is connected to the other end of the capacitor C2 as the negative electrode GND3.

[0021] The chip power supply feedback circuit is composed of a diode D3 with the positive electrode connected to VCC1 and a negative electrode divided into two paths, one connected to pin 1 of the control chip U1 and the other connected to capacitor C4. The other end of the capacitor C4 is connected to pin 8 of the control chip U1.

[0022] Preferably: the coupled inductor T1 is connected in series with the coupled inductor T2, and pin 3 of the coupled inductor T1 is connected to pin 1 of the coupled inductor T2.

[0023] Preferably: the control chip U1 is a PWM control chip.

[0024] How it works

[0025] When the power is powered on, the input DC voltage is filtered by capacitor C3 and connected to pins 5 and 6 of the control chip U1. After the control chip U1 is powered on, it starts to work, and the input DC power is chopped by the internal switch tube. When the internal switch tube is turned on, the voltage is output from pin 8 of the control chip U1. The voltage first passes through the positive electrode of the diode D4, and then enters the coupled inductor composed of T1 and T2 in series. The current of the coupled inductor T1 and T2 begins to rise linearly. As the current of the coupled inductor T1 and T2 rises, the voltage VCC1 across the capacitors C5 and C6 also begins to rise. At the same time, since the phases of pins 4 and 1 of the coupled inductors T1 and T2 are opposite, the diodes D1 and D2 are not conducting.

[0026] When the internal switch is turned off, the coupled inductors T1 and T2 continue to flow through the diode D4. At this time, the coupled inductor current decreases. At the same time, since the 4th and 1st pins of the coupled inductors T1 and T2 are in opposite phase, the diodes D1 and D2 are turned on to release the energy stored in the coupled inductors T1 and T2 to C1 and C2 respectively, and the voltages of VCC2 and VCC3 gradually increase. Due to the accumulation of the PWM control circuit cycle, the VCC1 voltage gradually increases and continues to supply power to the 1st pin of the control chip U1 through the diode D3 and the capacitor C4, and also serves as voltage feedback, thus completing the startup process. At this time, the VCC1 voltage continues to rise. When the output voltage reaches the set voltage of the PWM control chip U1, the control chip automatically reduces the duty cycle to reduce the output voltage, and then repeats the above process. Finally, VCC1 stabilizes to the set value of the chip U1. Since the primary of the coupled inductor is a series structure, the output voltages of VCC2 and VCC3 are finally half of VCC1.

[0027] like Figure 2 The figure shows the application circuit diagram of the utility model. The input voltage range is 30-100V, the output power is 5W, and there are three output voltages in total, one non-isolated 12V, and two isolated 5Vs, 5Va and 5Vb respectively. The circuit can be used as an auxiliary power supply inside the motor controller, where 12V can power the drive circuit; 5Va can power the isolated communication part, such as isolated CAN; 5Vb can power instrument pulses, etc.

[0028] The switching power supply of the utility model has high flexibility, and can form different voltages and realize multi-channel isolated output by connecting different numbers of coupled inductors in series and parallel. It adopts BUCK topology and a dedicated PWM control chip, and has simple peripheral circuits and low costs.

[0029] The contents not described in detail in the present invention are all prior art.

[0030] The above is only a preferred embodiment of the utility model, and is not limited to the description in the specification and implementation. Therefore, any equivalent changes or modifications made according to the structure, features and principles described in the scope of the patent application of the utility model should be included in the scope of the patent application of the utility model, such as: T1 and T2 can use high-frequency transformers, and U1 can use any BUCK control chip or discrete circuit to complete the present invention.

Claims

1. A BUCK type switching power supply with dual-circuit isolated output, comprising a PWM control circuit, a power conversion circuit, a main output circuit, an isolation auxiliary circuit and a chip power supply feedback circuit, characterized in that: The PWM control circuit is composed of an input power supply, a capacitor C3 and a control chip U1. The input power supply is connected to the 5th and 6th pins of the control chip U1 via the capacitor C3 as input, and the 8th pin of the control chip U1 is used as an output terminal. The power conversion circuit is composed of the output terminal 8-pin of the control chip U1, the capacitor D4, and the coupled inductors T1 and T2. The 8-pin of the control chip U1 is connected to the cathode of the diode D4 and the 1-pin of the coupled inductor T1. The anode of the diode D4 is connected to GND. The 3-pin of the coupled inductor T1 is connected to the 1-pin of the coupled inductor T2. The main output circuit is composed of a coupling inductor T2, a capacitor C5 and a capacitor C6. The 3rd pin of the coupling inductor T2 is connected to the positive electrodes of the capacitors C5 and C6 as a non-isolated output VCC1, and the negative electrodes of the capacitors C5 and C6 are connected to GND as the negative electrode of the non-isolated output. The isolation auxiliary circuit is provided with two circuits, one of which is composed of a coupling inductor T1, a diode D1, and a capacitor C1, wherein the 4th pin of the coupling inductor T2 is connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is connected to one end of the capacitor C1 as the positive electrode VCC2, and the 2nd pin of the coupling inductor T1 is connected to the other end of the capacitor C2 as the negative electrode GND2; the other circuit is composed of a coupling inductor T2, a diode D2, and a capacitor C2, wherein the 4th pin of the coupling inductor T2 is connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is connected to one end of the capacitor C2 as the positive electrode VCC3, and the 2nd pin of the coupling inductor T2 is connected to the other end of the capacitor C2 as the negative electrode GND3.

2. A BUCK type switching power supply with dual-circuit isolated output according to claim 1, characterized in that: The chip power supply feedback circuit is composed of a diode D3 and a capacitor C4. The positive electrode of the diode D3 is connected to VCC1, and the negative electrode is divided into two paths, one is connected to pin 1 of the control chip U1, and the other is connected to the capacitor C4. The other end of the capacitor C4 is connected to pin 8 of the control chip U1.

3. The BUCK type switching power supply with dual-circuit isolated output according to claim 1, characterized in that: The coupling inductor T1 is connected in series with the coupling inductor T2, and the pin 3 of the coupling inductor T1 is connected to the pin 1 of the coupling inductor T2.

4. The BUCK type switching power supply with dual-circuit isolated output according to claim 1, characterized in that: The control chip U1 is a PWM control chip.

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