A flyback buck circuit capable of outputting a voltage of a standard amplitude

Abstract

The present application relates to a kind of voltage of standard amplitude that can output, the flyback BUCK circuit, the flyback BUCK circuit includes flyback high-frequency transformer (1), the flyback high-frequency transformer (1) has at least two outputs;Two of the at least two outputs are formed by the center tap of the secondary winding of transformer First output (A) and second output (B);The output end of the first output (A) is equipped with the first voltage stabilizing module (21) that can make the output end maintain stable positive standard amplitude voltage, the output end of the second output (B) is equipped with the second voltage stabilizing module (22) that can make the output end maintain stable negative standard amplitude voltage.The circuit output is stable, simple structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic circuits, in particular to a flyback BUCK circuit capable of outputting a voltage with a standard amplitude. BACKGROUND

[0002] At present, when an electric vehicle is charging, the vehicle control device confirms the maximum power supply current of the current power supply device by measuring the duty cycle of the PWM signal. According to the national standard GB / T 18487.1---2015 of the People's Republic of China, the amplitude of the PWM signal used for measurement must be ±12V voltage signal, while the ordinary flyback power supply is a positive voltage and cannot provide a-12V amplitude, which does not meet the national standard.

[0003] And the output amplitude provided by the current circuit is easily affected by load fluctuation, which can easily lead to substandard output voltage and affect the use performance of the charging pile. SUMMARY

[0004] In view of the above problems, the purpose of the present application is to provide a flyback BUCK circuit capable of outputting a voltage with a standard amplitude, which can stably and effectively output a voltage with a standard amplitude, meet the national standard requirements, and has a simple and reliable structure design.

[0005] In order to achieve the above purpose, the technical scheme of the present application is as follows: a flyback BUCK circuit capable of outputting a voltage with a standard amplitude, characterized in that:

[0006] The flyback BUCK circuit comprises a flyback high-frequency transformer, and the flyback high-frequency transformer has at least two outputs.

[0007] Two of the at least two outputs are formed by a center tap of a secondary winding of the transformer to form a first output and a second output.

[0008] The output end of the first output is provided with a first voltage stabilizing module capable of maintaining the output end at a stable positive standard amplitude voltage, and the output end of the second output is provided with a second voltage stabilizing module capable of maintaining the output end at a stable negative standard amplitude voltage.

[0009] Further, the first voltage stabilizing module comprises a control chip connected to the primary winding of the flyback high-frequency transformer, and a feedback component located at the output end of the first output to collect the output voltage and feed it back to the control chip for the control chip to control the on-off of the primary winding according to the feedback information.

[0010] Further, the feedback component comprises a first voltage stabilizing component for maintaining the output voltage of the first output at a positive standard amplitude voltage, and a conduction component connected between the first voltage stabilizing component and the output end of the first output.

[0011] The conducting component is also connected with the control chip to feed back the output voltage of the first output to the control chip.

[0012] Further, the conducting component is an optical coupling device, the light emitting diode side of the optical coupling device is connected between the output end of the first output and the first voltage stabilizing component, and the light receiving side is connected with the feedback end of the control chip.

[0013] Further, the control chip is a power supply chip with built-in MOS tube, the power supply chip is connected with the primary winding through the MOS tube and controls the on-off of the primary winding by controlling the on-off of the MOS tube.

[0014] Further, the second voltage stabilizing module comprises a second voltage stabilizing component connected with the output end of the second output, and a voltage dividing network connected with the reference voltage end of the second voltage stabilizing component and maintaining the output voltage of the second output as a negative standard amplitude by voltage dividing.

[0015] Further, the voltage dividing network comprises a first resistor and a second resistor connected in series at the output end of the second output, and the reference voltage end of the second voltage stabilizing component is connected between the first resistor and the second resistor.

[0016] Further, the first voltage stabilizing component and the second voltage stabilizing component are both 431 voltage stabilizers.

[0017] Further, the circuit further comprises a third output which is isolated from and independent of the first and second outputs.

[0018] Further, the standard amplitude is ±12V.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] The center tap is arranged at the secondary winding of the circuit to generate a reference ground, thereby solving the problem that the previous charging pile cannot output negative voltage; the voltage stabilizing module can effectively ensure the output of voltage with standard amplitude, thereby making the charging pile meet the national standard requirements, the third output is designed to make the charging pile have more functions, thereby improving the applicability of the charging pile, and the structure is simple in structure, easy to implement, high in stability, and improves the performance of the charging pile. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The present application can output Standard voltage of the flyback BUCK circuit. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0023] Figure 1 This application can output... Standard A preferred embodiment of a flyback BUCK circuit for outputting a standard amplitude voltage. This flyback BUCK circuit includes a flyback high-frequency transformer 1, which has at least two outputs. Two of these outputs are formed by a center tap on the secondary winding of the transformer, creating a first output A and a second output B. The output terminal of the first output A is equipped with a first voltage regulator module 21 that maintains a stable positive standard amplitude voltage at the output terminal. The output terminal of the second output B is equipped with a second voltage regulator module 22 that maintains a stable negative standard amplitude voltage at the output terminal.

[0024] like Figure 1 As shown, the first voltage regulator module 21 includes a control chip 211 connected to the primary winding (pin 1 / 3) of the flyback high-frequency transformer 1, and a feedback component 212 located at the output terminal of the first output A to collect the output voltage and feed it back to the control chip 211 so that the control chip 211 can control the on / off state of the primary winding according to the feedback information.

[0025] The feedback component 212 includes a first voltage regulator 2122 that maintains the output voltage of the first output A as a positive standard amplitude voltage, and a conduction component 2121 connected between the first voltage regulator 2122 and the output terminal of the first output A. The conduction component 2121 is also connected to the control chip 211 to feed back the output voltage of the first output A to the control chip 211.

[0026] In this embodiment, the conducting component 2121 is an optocoupler E7. The light-emitting diode side of the optocoupler E7 is connected between the output terminal of the first output A and the first voltage regulator 2122, while the light receiver side is connected to the feedback terminal FB of the control chip 211.

[0027] The control chip 211 is a power chip N17 with a built-in MOSFET. The power chip N17 is connected to the primary winding (pin 1 / 3) through the MOSFET and controls the on / off state of the primary winding (pin 1 / 3) by controlling the on / off state of the MOSFET.

[0028] When the output voltage of the first output A changes, the current flowing through E7 changes, at which time the current value fed back to the FB end also changes. The power chip N17 will control the on-off of the D, S, and GND three pins of the MOS tube according to the current value change to further control the on-off of the primary winding (1 / 3 pin), so as to adjust the output to maintain the standard amplitude.

[0029] The second voltage stabilizing module 22 comprises a second voltage stabilizing component 221 connected with the output end of the second output B, and a voltage dividing network 222 connected with the reference voltage end 1 pin of the second voltage stabilizing component 221 and maintaining the output voltage of the second output B as a negative standard amplitude through voltage dividing.

[0030] The voltage dividing network 222 comprises a first resistor and a second resistor connected in series at the output end of the second output B, and the reference voltage end of the second voltage stabilizing component is connected between the first resistor R215 and the second resistor R216. The reference voltage of the voltage stabilizing component is unchanged, and the resistance values of R215 and R216 can be determined according to the required amplitude size, so that the output voltage is maintained near the standard amplitude.

[0031] In the embodiment, the first voltage stabilizing component 2122 and the second voltage stabilizing component 221 are both 431 voltage stabilizers. Meanwhile, the circuit further comprises a third output C isolated from the first and second outputs A / B and independent, which can ensure that the insulation withstand voltage is greater than 3KV, and ensure that in case of communication circuit damage, the entire controller is not affected. Meanwhile, the voltage output by the third output C can be used for CAN, card swiping module, 485 circuit, external static electricity and interference prevention circuit, etc.

[0032] The first output A is output through the light coupling plus 431 and the loop regulation output voltage, and ensures the positive 12V voltage output, which is used for MCU, relay and other components. The second output B directly realizes the stable output of the negative 12V voltage through the 431 component combined with the voltage dividing network, so as to meet the standard requirements and be used for physical connection with the electric vehicle.

[0033] Next, the circuit is simply explained as follows:

[0034] 1. The input alternating current passes through the wire wound fuse resistor (used for preventing surge) and passes through the π type filter (mainly used for satisfying EMC), and then the alternating current is rectified and filtered into direct current voltage, and the series connection of the electrolytic capacitor can ensure that the input voltage reaches 380V without damage.

[0035] 2. The direct current voltage is divided by R119, R122, R125, R129 and R130 to collect the voltage value, which is fed back to the power chip N17 to control whether the output voltage is out of limit.

[0036] 3. The power chip N17 has a built-in MOSFET. The primary winding of the flyback high-frequency transformer, the built-in MOSFET in the power chip, and the current-limiting resistors R139 and R140 form the primary circuit. The three sets of load outputs are output through the flyback principle of the transformer.

[0037] 4. Pins 7, 8, and 9 of the transformer winding are used as reference ground through the center tap of pin 8. This can meet the standard requirement of ±12V (the voltage between pins 7 and 9 is 24V, but if it is changed to pin 8, then pins 7 and 8 will be ±12V, and pins 9 and 8 will be ±12V).

[0038] 5. Because the standard requires the output voltage error range to be within 0.6V, the positive 12V is connected to an optocoupler and a 431 microcontroller to form a loop. When the load changes, the positive 12V voltage is fed back to the primary circuit to ensure that the positive 12V voltage remains constant. Since the negative 12V has a small load capacity, it is divided by the 431 microcontroller to ensure that the negative 12V output is stable.

[0039] 6. This solution uses a common flyback BUCK chip and a transformer with three windings at the output. Through loop design and voltage regulation circuit design, the output ±12V error is guaranteed to be less than 0.6V.

[0040] The working circuit is as follows:

[0041] (1) Positive 12V positive half-cycle = through the same terminal 7 → VD14 Schottky diode conducts (R127 and C97 form an RC circuit to reduce RE interference) → CE6 electrolytic capacitor stores energy and synchronously provides energy to the load (C98 in parallel is to reduce ESR) → load resistor R336 conducts (when the external load is disconnected, this resistor can stabilize the cross regulation rate of the other two winding outputs);

[0042] (2) Positive 12V negative half-cycle = CE6 electrolytic capacitor provides energy to the load (C98 in parallel is to reduce ESR) → load resistor R336 conducts (when the external load is disconnected, this resistor can stabilize the cross regulation rate of the other two windings).

[0043] (3) Negative 12V positive half cycle = through the same terminal 8 → CE4 electrolytic capacitor stores energy and synchronously provides energy to the load (C90 in parallel is to reduce ESR) → 431 conducts and outputs -12V [(12KΩ / 3.1KΩ)+1]*2.5=12.17V through the voltage divider resistor → VD11 Schottky diode conducts (R123 and C91 form an RC circuit to reduce RE interference) → Resistor R217 is a current limiting resistor to prevent 431 from breaking down directly;

[0044] (4) Negative 12V negative half-cycle = CE4 electrolytic capacitor provides energy to the load (C90 in parallel is to reduce ESR) → 431 conducts and outputs -12V [(12KΩ / 3.1KΩ)+1]*2.5=12.17V through the voltage divider resistor → VD11 Schottky diode conducts (R123 and C91 form an RC circuit to reduce RE interference);

[0045] This application enables the output amplitude to be within 5% of the standard amplitude, i.e., 12V±0.6V. When the 12V voltage changes, it will be compared with the 431 reference voltage of 2.5V and fed back to the optocoupler to correct the duty cycle of the primary circuit, thereby adjusting the output voltage. The reference voltage error of the 431 is 0.8%, which meets the standard requirements.

[0046] Thus, by setting a center tap on the secondary winding of the circuit to generate a reference ground, the problem of charging piles being unable to output negative voltage is solved. The setting of the voltage regulator module can effectively ensure the output voltage of standard amplitude, so that the charging pile meets the national standard requirements. The design of the third output gives the charging pile more functions, thereby improving the applicability of the charging pile. Moreover, the structure is simple to set up, easy to implement, and highly stable, thus improving the performance of the charging pile.

[0047] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A flyback BUCK circuit capable of outputting a voltage of standard amplitude, characterized in that: The flyback BUCK circuit includes a flyback high-frequency transformer (1) having at least two outputs; Two of the at least two outputs are formed by setting a center tap on the secondary winding of the transformer to form a first output (A) and a second output (B). The first output (A) is provided with a first voltage regulator module (21) that can maintain a stable positive standard amplitude voltage at the output terminal, and the second output (B) is provided with a second voltage regulator module (22) that can maintain a stable negative standard amplitude voltage at the output terminal. The first voltage regulator module (21) includes a control chip (211) connected to the primary winding of the flyback high-frequency transformer (1) and a feedback component (212) located at the output terminal of the first output (A) to collect the output voltage and feed it back to the control chip (211) so that the control chip (211) can control the on / off state of the primary winding according to the feedback information; the feedback component (212) includes a first voltage regulator component (2122) that maintains the output voltage of the first output (A) as a positive standard amplitude voltage and a conduction component (2121) connected between the first voltage regulator component (2122) and the output terminal of the first output (A). The conducting component (2121) is also connected to the control chip (211) to feed back the output voltage of the first output (A) to the control chip (211). The conducting component (2121) is an optocoupler (E7). The light-emitting diode side of the optocoupler (E7) is connected between the output terminal of the first output (A) and the first voltage regulator (2122), while the light receiver side is connected to the feedback terminal of the control chip (211). The second voltage regulator module (22) includes a second voltage regulator component (221) connected to the output terminal of the second output (B) and a voltage divider network (222) connected to the reference voltage terminal of the second voltage regulator component (221) and maintaining the output voltage of the second output (B) at a negative standard amplitude through a voltage divider method. The voltage divider network (222) includes a first resistor (R215) and a second resistor (R216) connected in series at the output terminal of the second output (B), and the reference voltage terminal of the second voltage regulator (221) is connected between the first resistor (R215) and the second resistor (R216).

2. The flyback BUCK circuit capable of outputting a standard amplitude voltage according to claim 1, characterized in that: The control chip (211) is a power chip (N17) with a built-in MOS transistor. The power chip (N17) is connected to the primary winding through the MOS transistor and controls the on / off state of the primary winding by controlling the on / off state of the MOS transistor.

3. The flyback BUCK circuit capable of outputting a standard amplitude voltage according to claim 1, characterized in that: Both the first voltage regulator (2122) and the second voltage regulator (221) are 431 voltage regulators.

4. The flyback BUCK circuit capable of outputting a standard amplitude voltage according to claim 1, characterized in that: The circuit also includes a third output (C) that is isolated from and independent of the first and second outputs.

5. The flyback BUCK circuit capable of outputting a standard amplitude voltage according to claim 1, characterized in that: The standard amplitude is ±12V.

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