DC-DC auxiliary power supply circuit and DC-DC auxiliary power supply

Abstract

The utility model belongs to the field of electronic devices, and discloses a DC-DC auxiliary power supply circuit. The DC-DC auxiliary power supply circuit comprises a starting circuit and an auxiliary source circuit. The starting circuit comprises a first resistor R1, a second resistor R2, a voltage-regulator tube Z1, a third resistor R3, a fourth resistor R4, a voltage reference chip U1, a fifth resistor R5, a field effect transistor Q1 and a triode Q2. The auxiliary source circuit comprises an auxiliary source winding T1 and a rectifier diode D1. Current control characteristics of a field effect transistor and a triode are utilized, voltage of an auxiliary power supply and main current are supplied separately, a voltage reference chip U1 is utilized to generate a stable voltage source, small current of a triode Q2 is utilized to control a main current source coupled by an auxiliary source winding T1, only the small current can pass through the field effect transistor Q1, and the main current can pass through the field effect transistor Q1. In the starting circuit, a particularly small current is used for controlling a large current in the auxiliary source circuit, and the loss of the small current in a starting system is small, so that a stable auxiliary power supply voltage can be obtained, the loss can be reduced, and the starting circuit is suitable for a wide-range, high-voltage and high-efficiency power supply module.

Description

Technical Field

[0001] The utility model belongs to the field of electronic devices and relates to a DC-DC auxiliary power supply circuit and a DC-DC auxiliary power supply. Background Art

[0002] In recent years, electrical equipment has placed increasingly stringent demands on power modules for input voltage range, output power, conversion efficiency, and power density. Currently, auxiliary power is generated via transformer coupling and rectifier diodes. This results in a wide range of voltage variations with input voltage. Furthermore, when the auxiliary power supply is started, the startup resistor consumes additional energy.

[0003] Especially under wide-range, high-voltage input voltages, the current auxiliary power supply voltage will vary significantly. On the one hand, the voltage tolerance requirements for the PWM control chip are higher, and on the other hand, the auxiliary power supply is required to provide a stable voltage to the system's control, sampling, protection, logic, and drive circuits, so the auxiliary power supply voltage cannot fluctuate significantly. In addition, from an efficiency perspective, under high input voltage conditions, even small changes in input current will lead to large changes in efficiency.

[0004] Therefore, it is necessary to design an auxiliary power supply with higher stability to ensure that the auxiliary power supply voltage can still be maintained in a relatively stable range under the conditions of a wide range and high voltage input voltage. Utility Model Content

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a DC-DC auxiliary power supply circuit and a DC-DC auxiliary power supply.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a DC-DC auxiliary power supply circuit, including a startup circuit and an auxiliary power circuit; the startup circuit includes a first resistor R1, a second resistor R2, a voltage regulator Z1, a third resistor R3, a fourth resistor R4, a voltage reference chip U1, a fifth resistor R5, a field effect transistor Q1, and a transistor Q2; one end of the first resistor R1 is used to connect to a bus, and the other end is connected to one end of the voltage regulator Z1 and one end of the second resistor R2; the other end of the second resistor R2 is connected to the anode of the voltage reference chip U1 and the gate of the field effect transistor Q1; the reference point of the voltage reference chip U1 is connected to the third resistor R3. The drain of the field effect transistor Q1 is used to connect to the busbar, and the source is connected to the other end of the third resistor R3 and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the base of the transistor Q2. The other end of the voltage regulator Z1, the cathode of the voltage reference chip U1, and the other end of the fourth resistor R4 are grounded. The auxiliary source circuit includes an auxiliary source winding T1 and a rectifier diode D1. The like-name end of the auxiliary source winding T1 is grounded, and the opposite-name end is connected to the anode of the rectifier diode D1. The cathode of the rectifier diode D1 is connected to the collector of the transistor Q2. The emitter of the transistor Q2 is used to connect to the power supply end of the main control chip IC.

[0008] Optionally, the startup circuit further includes a first capacitor C1; one end of the first capacitor C1 is connected to the source of the field effect transistor Q1, and the other end is grounded.

[0009] Optionally, the auxiliary source circuit further includes a second capacitor C2; one end of the second capacitor C2 is connected to the emitter of the transistor Q2, and the other end is grounded.

[0010] Optionally, the auxiliary source circuit further includes a third capacitor C3; one end of the third capacitor C3 is connected to the cathode of the rectifier diode D1, and the other end is grounded.

[0011] Optionally, the voltage reference chip U1 adopts a parallel voltage regulator integrated circuit TL431.

[0012] Optionally, the reference voltage provided by the voltage reference chip U1 is 2.5V.

[0013] Optionally, the first resistor R1 and the voltage regulator diode Z1 are used to convert the bus voltage into 18V and output it to the second resistor R2.

[0014] Optionally, the bus voltage VIN_BUS is 120~500V.

[0015] Optionally, the voltage difference between the base and emitter of the transistor Q2 is 0.6V.

[0016] In a second aspect, the present invention provides a DC-DC auxiliary power supply, which is obtained by encapsulating the above-mentioned DC-DC auxiliary power supply circuit.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a DC-DC auxiliary power supply circuit, comprising a startup circuit and an auxiliary power supply circuit. The startup circuit includes a first resistor R1, a second resistor R2, a voltage regulator diode Z1, a third resistor R3, a fourth resistor R4, a voltage reference chip U1, a fifth resistor R5, a field-effect transistor Q1, and a transistor Q2. The auxiliary power supply circuit includes an auxiliary power supply winding T1 and a rectifier diode D1. The startup circuit draws power from the busbar to supply the required startup voltage to the main control chip IC at the first moment of power-up. The current control characteristics of the field-effect transistors and transistors are utilized to separate the auxiliary power supply voltage from the main current. The voltage reference chip U1 generates a stable voltage source, and the low current of the transistor Q2 controls the main current source coupled from the auxiliary power supply winding T1. Only a small current flows through the field-effect transistor Q1. In the startup circuit, a particularly small current is used to control the large current in the auxiliary power supply circuit, resulting in minimal losses in the startup system. This ensures a stable auxiliary power supply voltage and reduces losses, resulting in high circuit efficiency. The circuit is particularly suitable for wide-range, high-voltage, and high-efficiency power supply modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the topology diagram of the DC-DC auxiliary power supply circuit of the present utility model. DETAILED DESCRIPTION

[0020] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] The present invention is described in further detail below with reference to the accompanying drawings:

[0023] See also Figure 1 In one embodiment of the present invention, a DC-DC auxiliary power supply circuit is provided that can effectively improve the auxiliary power supply voltage output stability and reduce losses, thereby improving the reliability and power efficiency of power supply products. Specifically, the DC-DC auxiliary power supply circuit of the present invention includes a startup circuit and an auxiliary power circuit.

[0024] Among them, the startup circuit includes a first resistor R1, a second resistor R2, a voltage regulator Z1, a third resistor R3, a fourth resistor R4, a voltage reference chip U1, a fifth resistor R5, a field effect transistor Q1 and a transistor Q2; one end of the first resistor R1 is used to connect to the bus, and the other end is connected to one end of the voltage regulator Z1 and one end of the second resistor R2, and the other end of the second resistor R2 is connected to the anode of the voltage reference chip U1 and the gate of the field effect transistor Q1; the reference point of the voltage reference chip U1 is connected to one end of the third resistor R3 and one end of the fourth resistor R4; the drain of the field effect transistor Q1 is used to connect to the bus, and the source is connected to the other end of the third resistor R3 and one end of the fifth resistor R5, and the other end of the fifth resistor R5 is connected to the base of the transistor Q2; the other end of the voltage regulator Z1, the cathode of the voltage reference chip U1 and the other end of the fourth resistor R4 are grounded.

[0025] The auxiliary source circuit includes an auxiliary source winding T1 and a rectifier diode D1; the like-name end of the auxiliary source winding T1 is grounded, and the opposite-name end is connected to the anode of the rectifier diode D1; the cathode of the rectifier diode D1 is connected to the collector of the transistor Q2; and the emitter of the transistor Q2 is used to connect to the power supply end of the main control chip IC.

[0026] This utility model features a DC-DC auxiliary power supply circuit, designed with a startup circuit and an auxiliary power supply circuit. The startup circuit draws power from the busbar to supply the required startup voltage to the main control chip IC at the first moment of power-up. Utilizing the current control characteristics of field-effect transistors and triodes, the auxiliary power supply voltage is supplied separately from the main current. A stable voltage source is generated using voltage reference chip U1, and the low current of triode Q2 controls the main current source coupled from auxiliary source winding T1. Only a small current flows through field-effect transistor Q1, allowing a particularly small current in the startup circuit to control the large current in the auxiliary source circuit. This small current results in minimal losses in the startup system, resulting in a stable auxiliary power supply voltage and reduced losses, resulting in a high circuit efficiency. The circuit is particularly suitable for wide-range, high-voltage, and high-efficiency power supply modules.

[0027] Specifically, the first and second resistors R1 and R2 are primarily used for current limiting, while the field-effect transistor Q1 is primarily used to controllably transmit the voltage required for startup. The voltage reference chip U1, the third resistor R3, and the fourth resistor R4 form an adjustable voltage system. Optionally, the voltage reference chip U1 provides a 2.5V reference voltage for the adjustable voltage system, and then the resistance values ​​of the third and fourth resistors R3 and R4 are modified to provide a stable, suitable voltage value for the main control chip IC. The fifth resistor R5 is primarily used for current limiting, providing an extremely small current to act on the transistor Q2. This, in turn, leverages the transistor's characteristics to control the high current in the auxiliary source circuit with a very small current in the startup circuit. The auxiliary source winding T1 is primarily used to couple an AC voltage from the busbar, and the rectifier diode D1 utilizes the diode's unidirectional conductivity to convert AC into DC.

[0028] In a possible implementation, the startup circuit further includes a first capacitor C1 ; one end of the first capacitor C1 is connected to the source of the field effect transistor Q1 , and the other end is grounded.

[0029] Optionally, the auxiliary source circuit further includes a second capacitor C2; one end of the second capacitor C2 is connected to the emitter of the transistor Q2, and the other end is grounded.

[0030] Optionally, the auxiliary source circuit further includes a third capacitor C3; one end of the third capacitor C3 is connected to the cathode of the rectifier diode D1, and the other end is grounded.

[0031] Specifically, the first capacitor C1, the second capacitor C2, and the third capacitor C3 are all designed to be used in the circuit as decoupling capacitors. Their main function is to buffer voltage fluctuations and effectively prevent voltage spikes and drops, thereby ensuring the stability and reliability of the circuit.

[0032] In one possible embodiment, the voltage reference chip U1 adopts a parallel voltage regulator integrated circuit TL431. Specifically, TL431 is an adjustable precision parallel voltage regulator produced by Texas Instruments, with three pins: cathode, anode and reference point. The internal circuit core of TL431 is a 2.5V reference voltage source, as well as a multi-stage amplifier circuit, compensation circuit and protection circuit designed around it. When the reference point voltage exceeds 2.5V, TL431 turns on and maintains a stable output voltage by adjusting the current between the anode and cathode. Its equivalent function can be regarded as consisting of three parts: a reference voltage source, a comparator and an output switch. As the voltage reference chip U1, TL431 can provide a stable and adjustable reference voltage.

[0033] The TL431 has the following application advantages: 1. High Precision: The TL431 has a high-precision and stable reference voltage output function, suitable for a variety of high-precision circuits. 2. Wide Adjustable Voltage Range: By selecting appropriate external resistors, the TL431's output voltage can be adjusted arbitrarily between 2.5V and 36V. 3. Strong Current Regulation: The TL431 has excellent current regulation capabilities, ensuring circuit stability under various load conditions. 4. Wide Application: The TL431 can be used not only as a shunt regulator, but also in series regulators, parallel current expansion regulator circuits, constant current sources, comparators, and error amplifiers for switching power supplies.

[0034] In a possible implementation, the first resistor R1 and the voltage regulator diode Z1 are used to convert the bus voltage into 18V and output it to the second resistor R2.

[0035] Optionally, the bus voltage VIN_BUS is 120~500V.

[0036] Optionally, the voltage difference between the base and emitter of the transistor Q2 is 0.6V.

[0037] The working process and principle of the DC-DC auxiliary power supply circuit of this utility model:

[0038] 1. After the bus voltage VIN_BUS voltage (120~500V) is powered on, it passes through the first resistor R1 to limit the current and the voltage regulator Z1 to stabilize the voltage, and the voltage V is obtained. Z =18V.

[0039] 2. The voltage Vz is used to drive the field effect tube Q1 to conduct through the second resistor R2. The voltage reference chip U1, the third resistor R3 and the fourth resistor R4 are used to set the required voltage V B .

[0040] 3. Vcc acts on the power supply terminal VDD of the main control chip IC after being limited by the fifth resistor R5 and the Vbe=0.6V voltage drop of the transistor Q2.

[0041] 4. After the main control chip IC is started, the auxiliary power circuit works Vcc>V B , using transistor Q1 Characteristics, V B Provides voltage, IC provides high current to the main control chip IC, thereby improving efficiency and reliability.

[0042] In another embodiment of the present invention, a DC-DC auxiliary power supply is provided. The DC-DC auxiliary power supply is obtained by packaging the above-mentioned DC-DC auxiliary power supply circuit.

[0043] Specifically, packaging is a key step in electronics manufacturing, and a DC-DC auxiliary power supply is obtained by integrating components of a DC-DC auxiliary power supply circuit into a compact and reliable packaging structure.

[0044] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A DC-DC auxiliary power supply circuit, characterized in that: Including starting circuit and auxiliary power circuit; The startup circuit includes a first resistor R1, a second resistor R2, a voltage regulator Z1, a third resistor R3, a fourth resistor R4, a voltage reference chip U1, a fifth resistor R5, a field effect transistor Q1 and a transistor Q2; One end of the first resistor R1 is used to connect to the busbar, and the other end is connected to one end of the voltage regulator Z1 and one end of the second resistor R2. The other end of the second resistor R2 is connected to the anode of the voltage reference chip U1 and the gate of the field effect transistor Q1. The reference point of the voltage reference chip U1 is connected to one end of the third resistor R3 and one end of the fourth resistor R4. The drain of the field effect transistor Q1 is used to connect to the busbar, and the source is connected to the other end of the third resistor R3 and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the base of the transistor Q2. The other end of the voltage regulator Z1, the cathode of the voltage reference chip U1, and the other end of the fourth resistor R4 are grounded. The auxiliary source circuit includes an auxiliary source winding T1 and a rectifier diode D1; the like-name end of the auxiliary source winding T1 is grounded, and the opposite-name end is connected to the anode of the rectifier diode D1; the cathode of the rectifier diode D1 is connected to the collector of the transistor Q2; and the emitter of the transistor Q2 is used to connect to the power supply end of the main control chip IC.

2. The DC-DC auxiliary power supply circuit according to claim 1, characterized in that: The startup circuit further includes a first capacitor C1; One end of the first capacitor C1 is connected to the source of the field effect transistor Q1 , and the other end is grounded.

3. The DC-DC auxiliary power supply circuit according to claim 2, characterized in that: The auxiliary source circuit further includes a second capacitor C2; One end of the second capacitor C2 is connected to the emitter of the transistor Q2 , and the other end is grounded.

4. The DC-DC auxiliary power supply circuit according to claim 3, characterized in that: The auxiliary source circuit further includes a third capacitor C3; One end of the third capacitor C3 is connected to the cathode of the rectifier diode D1 , and the other end is grounded.

5. The DC-DC auxiliary power supply circuit according to claim 1, characterized in that: The voltage reference chip U1 adopts a parallel voltage regulator integrated circuit TL431.

6. The DC-DC auxiliary power supply circuit according to claim 1, characterized in that: The reference voltage provided by the voltage reference chip U1 is 2.5V.

7. The DC-DC auxiliary power supply circuit according to claim 1, characterized in that: The first resistor R1 and the voltage regulator Z1 are used to convert the bus voltage into 18V and output it to the second resistor R2.

8. The DC-DC auxiliary power supply circuit according to claim 1, characterized in that: The voltage VIN_BUS of the bus is 120~500V.

9. The DC-DC auxiliary power supply circuit according to claim 1, characterized in that: The voltage difference between the base and emitter of the transistor Q2 is 0.6V.

10. A DC-DC auxiliary power supply, characterized in that: The DC-DC auxiliary power supply is obtained by packaging the DC-DC auxiliary power supply circuit according to any one of claims 1 to 9.

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