CN113433996B - Auxiliary power supply circuit with wide input voltage range - Google Patents

Abstract

The application provides an auxiliary power supply circuit with a wide input voltage range, which is used for supplying power to a working voltage conversion circuit connected with a direct-current power supply converter with the wide input voltage range, and comprises a voltage follower unit and a voltage comparison unit, wherein the voltage follower unit comprises an electronic switch, a resistor and a voltage stabilizing diode, a first end and a second end of the electronic switch are respectively and electrically connected with a voltage input end and a voltage output end of the working voltage conversion circuit, the resistor is electrically connected between the first end and a control end of the electronic switch, a cathode end of the voltage stabilizing diode is electrically connected with a control end of the electronic switch, and a detection end and an output end of the voltage comparison unit are respectively and electrically connected with a voltage input end of the working voltage conversion circuit and the control end of the electronic switch; the second end of the electronic switch can provide stable auxiliary voltage before and after the input voltage rises to the breakdown of the zener diode.

Description

Auxiliary power supply circuit with wide input voltage range

technical field

The invention relates to a power supply circuit, in particular to an auxiliary power supply circuit with a wide input voltage range.

Background technique

The feature of the wide input voltage range DC power converter is that it can receive an input voltage range from low voltage to high voltage, and generate an output voltage after conversion, and the output voltage can be maintained at a certain value to supply to the next stage circuit (load) . For example, the circuit architecture of the wide input voltage range DC power converter may include electronic components such as a transformer, an operating voltage conversion circuit, an integrated circuit (IC), a feedback circuit, and a transistor. The integrated circuit (IC) may, for example, It is a pulse width modulation controller (PWM controller) and the like.

In the aforementioned wide input voltage range DC power converter, the operating voltage of the electronic components comes from the operating voltage conversion circuit, the operating voltage conversion circuit can be, for example, a step-down circuit (Buck converter), the step-down circuit The received input voltage is the same as that of the DC power converter, and also falls within a wide input voltage range, and the step-down circuit converts the input voltage into the required operating voltage of the electronic components.

A stable working voltage is the basic requirement for each electronic component to maintain normal operation. However, in the actual operation of the step-down circuit, before reaching a stable state, for example, the input voltage and output voltage of the step-down circuit (ie When the size of the working voltage is close, the waveform of the output voltage of the step-down circuit will have ripple (ripple) instability, resulting in the instability of the working voltage provided to the electronic components, which directly affects the performance of the electronic components. working normally.

Contents of the invention

The main purpose of the present invention is to provide an auxiliary power supply circuit with a wide input voltage range, which is connected to a working voltage conversion circuit of a DC power converter with a wide input voltage range, so that before the working voltage conversion circuit reaches a stable voltage state, by this The invention provides the stable working voltage required by the electronic components, so as to overcome the shortcomings of the electronic components in the prior art that fail to receive the stable working voltage and thus fail to operate normally.

The auxiliary power supply circuit with a wide input voltage range of the present invention supplies power to a working voltage conversion circuit connected to a DC power converter with a wide input voltage range, and includes:

A voltage follower unit, including:

An electronic switch has a first end, a second end and a control end, the first end is electrically connected to a voltage input end of the working voltage conversion circuit, and the second end is electrically connected to a voltage of the working voltage conversion circuit output terminal;

a resistor electrically connected between the first terminal and the control terminal of the electronic switch; and

a Zener diode, the cathode terminal of which is electrically connected to the control terminal of the electronic switch; and

A voltage comparison unit includes a detection terminal and an output terminal, the detection terminal is electrically connected to the voltage input terminal of the working voltage conversion circuit, and the output terminal of the voltage comparison unit is electrically connected to the control terminal of the electronic switch.

In the aforementioned auxiliary power supply circuit with a wide input voltage range, the electronic switch of the voltage follower unit is a first electronic switch, the breakdown voltage of the Zener diode is less than a threshold voltage, and the threshold voltage is equal to the operating voltage A steady-state output voltage of the conversion circuit, the breakdown voltage of the Zener diode is smaller than the steady-state output voltage; the voltage comparison unit includes: a comparator with a non-inverting input terminal, an inverting input terminal and an output terminal , the non-inverting input terminal is used as the detection terminal of the voltage comparison unit, the inverting input terminal is electrically connected to a reference voltage, the reference voltage corresponds to a protection voltage, and the protection voltage is greater than the threshold voltage; and a second electronic switch, It has a first terminal, a second terminal and a control terminal, the first terminal of the second electronic switch is used as the output terminal of the voltage comparison unit, the second terminal of the second electronic switch is grounded, and the second electronic switch The control end of the switch is electrically connected to the output end of the comparator.

In the aforementioned auxiliary power supply circuit with a wide input voltage range, the first electronic switch is a bipolar junction transistor, and its first terminal, second terminal and control terminal are respectively a collector terminal, an emitter terminal and a base terminal.

In the aforementioned auxiliary power supply circuit with a wide input voltage range, the second electronic switch is an N-channel metal-oxide-semiconductor field-effect transistor, and its first terminal, second terminal and control terminal are respectively a drain terminal, a source terminal and a gate terminal.

When the input voltage received by the working voltage conversion circuit is close to the output voltage in its stable state, the output voltage will generate voltage ripple (ripple) instability, at this time, according to the auxiliary power supply of the wide input voltage range of the present invention The circuit structure of the circuit, in the voltage follower, when the input voltage rises to before the zener diode breaks down, the voltage at the second end of the electronic switch is approximately equal to the input voltage, which can be directly provided as an auxiliary voltage for the wide input voltage range An electronic component of a DC power converter; when the input voltage rises to the point where the Zener diode breaks down, the second terminal of the electronic switch can provide a regulated and stable auxiliary voltage to the electronic component. As mentioned above, before and after the input voltage rises to the breakdown of the zener diode, the electronic components can be operated normally under the stable working voltage, which overcomes the failure of the electronic components to receive the stable working voltage in the prior art. The downside of not functioning properly. As the input voltage increases, when the working voltage conversion circuit reaches a stable voltage state, its output voltage is stable, and the voltage comparison unit can close the electronic switch of the voltage follower unit.

Description of drawings

FIG. 1 is a schematic block diagram of an embodiment of an auxiliary power supply circuit with a wide input voltage range of the present invention electrically connected to a DC power converter with a wide input voltage range.

FIG. 2 is a schematic circuit diagram of an embodiment of an auxiliary power supply circuit with a wide input voltage range according to the present invention.

FIG. 3 is a schematic circuit diagram of an embodiment of an auxiliary power supply circuit with a wide input voltage range according to the present invention.

FIG. 4 is a voltage timing diagram of an embodiment of an auxiliary power supply circuit with a wide input voltage range according to the present invention.

Explanation of reference numbers:

10 Wide Input Voltage Range DC Power Converters

100 working voltage conversion circuit 101 voltage input terminal

102 voltage output terminal 200 auxiliary power supply circuit

20 voltage follower unit 300 output

30 voltage comparison unit 31 comparator

Vin input voltage Vout output voltage

V _B output voltage Vcc operating voltage

Q1 electronic switch R3 resistor

ZD1 Zener diode V _E auxiliary voltage

V _DET detection terminal R1 resistor

R2 Resistor Q2 Second Electronic Switch

V _Z Breakdown Voltage C1 Capacitor

V _x the voltage at the control terminal of the electronic switch

Detailed ways

The technical means adopted by the present invention to achieve the intended invention purpose are further described below in conjunction with the drawings and preferred embodiments of the present invention.

Please refer to FIG. 1, the wide input voltage range auxiliary power supply circuit 200 of the present invention can be applied in a wide input voltage range DC power converter 10, the feature of the wide input voltage range DC power converter 10 is that it can receive low voltage to high voltage The input voltage range of the voltage, and an output voltage Vout is generated after conversion, and the output voltage Vout can be maintained at a certain value to supply to the next stage circuit (load). Generally speaking, the circuit structure of the wide input voltage range DC power converter 10 may include electronic components such as a transformer, an operating voltage conversion circuit, an integrated circuit (IC), a feedback circuit, and a transistor, etc., and the operating voltage of the electronic components is from the operating voltage conversion circuit; for example, the integrated circuit (IC) can be, for example, a pulse width modulation controller (PWM controller)...etc.

Please refer to FIG. 2, the working voltage conversion circuit 100 has a voltage input terminal 101 and a voltage output terminal 102, the voltage input terminal 101 is used to receive a DC input voltage Vin, the range of the input voltage Vin is a wide input voltage range, The voltage output terminal 102 generates an output voltage V _B . When the input voltage Vin is greater than a threshold voltage, the working voltage conversion circuit 100 can reach a stable voltage state, so that the output voltage V _B can be maintained at a certain value to form a steady-state output voltage, and the steady-state output voltage can be used as the desired voltage. The working voltage Vcc of the above-mentioned electronic components, wherein, the threshold voltage can be equal to the steady-state output voltage; for example, the input voltage Vin can fall within the DC voltage range of 0V to 160V, and the steady-state output voltage can be equal to the steady-state output voltage The threshold voltage can be a fixed value of 12V, but not limited to the aforementioned voltage value. The working voltage conversion circuit 100 can be, for example, an existing Buck circuit, Forward circuit, Flyback circuit, Push-Pull circuit, etc. The voltage conversion circuit 100 here is a Buck circuit as an example.

As shown in FIG. 2 , an embodiment of the auxiliary power supply circuit 200 of the present invention includes a voltage follower unit 20 and a voltage comparison unit 30 .

The voltage follower unit 20 includes an electronic switch Q1 , a resistor R3 and a Zener diode ZD1 . The electronic switch Q1 is a three-terminal element and has a first end, a second end and a control end, the first end is electrically connected to the voltage input end 101 of the working voltage conversion circuit 100, and the second end is electrically connected to the working The voltage output terminal 102 of the voltage conversion circuit 100, and the second terminal is used to output an auxiliary voltage V _E , the auxiliary voltage V _E can be slightly lower than the steady-state output voltage, for example, can be less than 1V; the resistor R3 is electrically connected to Between the first terminal and the control terminal of the electronic switch Q1; the cathode terminal of the voltage stabilizing diode ZD1 is electrically connected to the control terminal of the electronic switch Q1, the anode terminal of the voltage stabilizing diode ZD1 can be grounded, and the striker of the voltage stabilizing diode ZD1 The breakdown voltage V _Z is less than the steady-state output voltage. Wherein, the electronic switch Q1 can be a transistor, such as a bipolar junction transistor (BJT), but it is not limited thereto. In the embodiment shown in FIG. 2, the first terminal of the electronic switch Q1 is a collector terminal (Collector ), the second terminal is the emitter terminal (Emitter), and the control terminal is the base terminal (Base). Therefore, the connection structure of the electronic switch Q1 and the resistor R3 forms an emitter follower (Emitter follower), when the electronic switch Q1 is turned on, the auxiliary voltage V _E is the base voltage of the electronic switch Q1 minus 0.7V; when the electronic switch Q1 is cut off, the auxiliary voltage V _E is closed without output.

The voltage comparison unit 30 includes a detection terminal V _DET and an output terminal 300, the detection terminal V _DET is electrically connected to the voltage input terminal 101 of the working voltage conversion circuit 100 to detect the magnitude of the input voltage Vin, the implementation shown in Figure 2 In an example, the detection terminal V _DET of the voltage comparison unit 30 detects the magnitude of the input voltage Vin through a voltage divider circuit formed by two resistors R1 and R2; the output terminal 300 of the voltage comparison unit 30 is electrically connected to the electronic switch Q1 The control terminal of the electronic switch Q1 is driven to be turned on or off according to the magnitude of the input voltage Vin.

In the embodiment of the present invention, please refer to FIG. 3. For convenience of description, the electronic switch Q1 of the voltage follower unit 20 is called a first electronic switch. A feasible embodiment of the voltage comparison unit 30 may include a comparator 31 and A second electronic switch Q2.

The comparator 31 has a non-inverting input terminal, an inverting input terminal and an output terminal, the non-inverting input terminal serves as the detection terminal V _DET of the voltage comparison unit 30, and the inverting input terminal is electrically connected to a reference voltage Vref , the reference voltage Vref corresponds to a protection voltage, the protection voltage is greater than the threshold voltage, and the reference voltage Vref can be equal to the divided voltage of the protection voltage in the resistor R2, as mentioned above, the threshold voltage can be 12V , the protection voltage can be 15V; the second electronic switch Q2 is a three-terminal element and has a first terminal, a second terminal and a control terminal, and the first terminal of the second electronic switch Q2 is used as the voltage comparison unit 30 The output terminal 300 of the second electronic switch Q2 can be grounded, and the control terminal of the second electronic switch Q2 is electrically connected to the output terminal of the comparator 31 . Wherein, the second electronic switch Q2 can be a transistor, such as a bipolar junction transistor (BJT) or a field effect transistor (FET), but not limited thereto. In the embodiment shown in FIG. 3 , the second electronic switch Q2 is an N-channel metal oxide semiconductor field effect transistor (N-channel MOSFET) as an example, its first terminal is the drain terminal (Drain), its second terminal is the source terminal (Source), and its control terminal is the gate terminal ( Gate).

The technical effect achieved based on the circuit architecture of the present invention will be described below with the waveform diagram shown in FIG. 4 . Whether the working voltage conversion circuit 100 reaches a steady state depends on whether the input voltage Vin is greater than the threshold value. The input voltage Vin starts from 0V. Before the time point t1, based on the characteristics of the emitter follower, the voltage at the second terminal of the electronic switch Q1 is approximately equal to the input voltage Vin, which can be directly provided as an auxiliary voltage V _E to the For the electronic components of the DC power converter 10 with a wide input voltage range, the input voltage Vin is still too small to cause breakdown of the Zener diode ZD1, and the voltage of the detection terminal V _DET is also lower than the reference voltage Vref, so that the comparator 31 outputs a low potential, the second electronic switch Q2 is turned off, and the voltage V _X of the control terminal of the electronic switch Q1 can refer to FIG. 4 .

Between time points t1 and t2, the input voltage Vin is close to the output voltage V _B , causing the working voltage conversion circuit 100 to fail to reach a stable voltage state, so the waveform of the output voltage V _B between time points t1 and t2 can be seen. Unstable voltage ripple (ripple) causes a voltage drop. At this time, the input voltage Vin is large enough to cause the breakdown of the Zener diode ZD1, and the voltage V _X of the control terminal of the electronic switch Q1 remains at the Zener diode ZD1 The breakdown voltage V _Z can turn on the electronic switch Q1, so V _E =V _Z -0.7 (V) _. Because the electronic switch Q1 is turned on, it can output the auxiliary voltage _VE to supply the operating voltage Vcc, and the auxiliary voltage _VE can complement the voltage drop of the voltage ripple, thereby maintaining the stability of the operating voltage Vcc. Between time points t1 and t2, the input voltage Vin is still lower than the threshold voltage, the voltage of the detection terminal V _DET is still lower than the reference voltage Vref, and the second electronic switch Q2 is still turned off.

Between time points t2 and t3, the input voltage Vin reaches the threshold voltage, which means that the working voltage conversion circuit 100 has reached a stable voltage state, and can output a stable output voltage V _B (steady-state output voltage) as the working voltage. Vcc. At this time, the input voltage Vin has not yet reached the protection voltage, so the voltage of the detection terminal V _DET is still lower than the reference voltage Vref, and the second electronic switch Q2 is still turned off. On the other hand, as mentioned above, the breakdown voltage V _Z of the Zener diode ZD1 is lower than the output voltage V _B (steady-state output voltage) maintained at a constant value after voltage regulation, so for the electronic switch Q1, its The emitter terminal and the base terminal are in a reverse-bias state, causing the auxiliary voltage _VE to be passively turned off, and the working voltage Vcc is mainly provided by the output voltage V _B (steady-state output voltage).

After time point t3, the operating voltage Vcc has been provided by the output voltage _VB (steady-state output voltage). When the input voltage Vin reaches the protection voltage, so that the voltage of the detection terminal V _DET is greater than the reference voltage Vref, the comparator 31 outputs a high potential, and the second electronic switch Q2 is turned on, so that the voltage follows the electronic voltage of the coupling unit 20. The base terminal of switch Q1 is low and turned off. It should be noted that, in the present invention, the auxiliary voltage V _E is passively turned off at the time point t2 to t3, instead of directly turning off the electronic switch Q1 at the time point t2, so that the auxiliary voltage V _E can be effectively avoided at the moment of high-voltage startup. When the rising speed is faster than the output voltage V _B , the electronic switch Q1 will be subjected to high power instantaneously and cause burning.

To sum up, when the input voltage Vin is close to the threshold voltage, although the output voltage V _B produces voltage ripples (ripple) instability, but through the electronic switch Q1 of the voltage follower unit 20 of the present invention The two terminals provide a relatively stable auxiliary voltage _VE to achieve the technical effect of allowing the electronic components to operate normally under the stable working voltage Vcc. When the input voltage Vin is greater than the threshold voltage, it means that the working voltage conversion circuit 100 enters a stable voltage state, so its voltage output terminal 102 provides the output voltage V _B (steady-state output voltage) as the working voltage Vcc to the electronic components. On the whole, no matter whether the input voltage Vin is low voltage or high voltage, the working voltage Vcc is stable to ensure the normal operation of the electronic components.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this professional technology Personnel, without departing from the scope of the technical solution of the present invention, when the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solution of the present invention.

Claims (3)

1. An auxiliary power supply circuit with a wide input voltage range, characterized in that the power supply is connected to a working voltage conversion circuit of a wide input voltage range DC power converter, and includes: A voltage follower unit, including: An electronic switch has a first terminal, a second terminal and a control terminal, the first terminal is electrically connected to a voltage input terminal of the working voltage conversion circuit, and the second terminal is electrically connected to the working voltage conversion circuit a voltage output terminal of the circuit; a resistor electrically connected between the first terminal and the control terminal of the electronic switch; and a Zener diode, the cathode terminal of which is electrically connected to the control terminal of the electronic switch; and A voltage comparison unit, including a detection terminal and an output terminal, the detection terminal is electrically connected to the voltage input terminal of the working voltage conversion circuit, and the output terminal of the voltage comparison unit is electrically connected to the control terminal of the electronic switch; The electronic switch of the voltage follower unit is a first electronic switch, the breakdown voltage of the Zener diode is less than a threshold voltage, the threshold voltage is equal to a steady-state output voltage of the working voltage conversion circuit, and the The breakdown voltage of the Zener diode is less than the steady-state output voltage; The voltage comparison unit includes: A comparator, having a non-inverting input terminal, an inverting input terminal and an output terminal, the non-inverting input terminal is used as the detection terminal of the voltage comparison unit, and the inverting input terminal is electrically connected to a reference voltage , the reference voltage corresponds to a protection voltage, and the protection voltage is greater than the threshold voltage; and A second electronic switch has a first terminal, a second terminal and a control terminal, the first terminal of the second electronic switch serves as the output terminal of the voltage comparison unit, and the The second terminal is grounded, and the control terminal of the second electronic switch is electrically connected to the output terminal of the comparator. 2. The auxiliary power supply circuit with a wide input voltage range according to claim 1, wherein the first electronic switch is a bipolar junction transistor, and its first terminal, second terminal and control terminal are respectively collectors electrode terminal, emitter terminal and base terminal. 3. The auxiliary power supply circuit of wide input voltage range according to claim 1, characterized in that, the second electronic switch is an N-channel metal-oxide-semiconductor field-effect transistor, and its first terminal, the second terminal and the control The terminals are the drain terminal, the source terminal and the gate terminal respectively.

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