An input voltage widening circuit

Abstract

An input voltage widening circuit includes a voltage divider unit, a photoelectric coupling switch unit, a comparator control unit and an output voltage switching switch unit, an external power supply is connected to the input end of the voltage divider unit, the voltage divider unit, the photoelectric coupling switch unit, the comparator control unit and the output voltage switching switch unit are connected in sequence, and the output voltage switching switch unit is used to control the switching between the external high voltage input end and the external low voltage input end. The circuit has a simple structure, a wide voltage input and efficient control, and can expand the input voltage range. The widening of the input voltage can increase the commonality of the product and reduce the cost.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to an input voltage widening circuit. Background Art

[0002] As people's living standards continue to improve, energy storage power supplies are becoming more and more widely used, and the requirements for power quality are becoming higher and higher. The quality of original power, including the mains power grid, may not meet the requirements of the equipment and must be converted by power electronic devices before use. Inverter power supply is an indispensable and important component.

[0003] A good inverter power supply can not only improve output efficiency, but also extend battery life (low standby loss and high efficiency). However, the traditional inverter has a high cost and is not conducive to mass production because the withstand voltage value of the output capacitor (commonly used is 400V or 450V) exceeds this specification, thus limiting the input voltage range of the product.

[0004] The input voltage range of the product can be calculated from the following formula: 1.414*Vout=N2 / N1*Vin min*Dmax (where: Vout is the output voltage of the inverter, N2 is the secondary turns of the transformer, N1 is the primary turns of the transformer, Vinmin is the minimum input voltage of the inverter, Vinmax is the maximum input voltage, Dmax is the duty cycle constant, generally 0.95 is selected). From the above formula, it can be calculated that when Vout=220V, it is also necessary to consider when the input voltage is the highest, 1.414*Vout≦435V (because the output capacitor uses a maximum withstand voltage of 450V, so a 15V derating is reserved), and the calculated input voltage range is only 12V-16.8V. At the same time, it is also necessary to use duty cycle adjustment to process it, and duty cycle adjustment will affect the overall efficiency of the product. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned technologies, the present invention provides an input voltage widening circuit, which has a simple circuit structure and efficient control of wide voltage input, and can expand the input voltage range. Widening the input voltage can increase the commonality of products and reduce costs.

[0006] To achieve the above object, the present invention is achieved as follows:

[0007] An input voltage widening circuit is characterized in that it includes a voltage divider unit, a photoelectric coupling switch unit, a comparator control unit and an output voltage switching switch unit, an external power supply is connected to the input end of the voltage divider unit, the voltage divider unit, the photoelectric coupling switch unit, the comparator control unit and the output voltage switching switch unit are connected in sequence, and the output voltage switching switch unit is used to control the switching between an external high voltage input end and an external low voltage input end.

[0008] Furthermore, the voltage divider unit includes a plurality of voltage divider resistors and a protection resistor, the plurality of voltage divider resistors are connected in series in sequence, the input end of the voltage divider resistor is connected to an external power supply, the output end of the voltage divider resistor is connected to a photoelectric coupling switch unit, the input end of the protection resistor is connected to the output end of the voltage divider resistor, and the output end of the protected resistor is grounded.

[0009] Furthermore, the voltage divider unit further includes a filter capacitor, an input end of the filter capacitor is connected to a common end of the voltage divider resistor and the protection resistor, and an output end of the filter capacitor is connected to a common end of the protection resistor and the ground terminal.

[0010] Furthermore, the photoelectric coupling switch unit includes a controllable voltage regulator and a photoelectric coupler, the input end of the photoelectric coupler is connected to the cathode of the controllable voltage regulator, the reference pole of the controllable voltage regulator is connected to the output end of the voltage divider unit, the anode of the controllable voltage regulator is connected to the common end of the protection resistor and the ground end, and the output end of the photoelectric coupler is connected to the comparator control unit.

[0011] Further, the comparator control unit includes a first transistor, a MOS transistor, a second transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor; one end of the first resistor is connected to the external 12V voltage terminal, the other end of the first resistor is connected to one of the output ends of the photoelectric coupler, the other output end of the photoelectric coupler is connected to the emitter of the first transistor, the base of the first transistor is connected to the common end of the first resistor and the photoelectric coupler, the collector of the first transistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to the common end of the first resistor and the external 12V voltage terminal, the gate of the MOS tube is connected to the common end of the second resistor and the third resistor, and one end of the fourth resistor is connected to the common end of the third resistor and the MOS tube The first transistor and the second transistor are connected to each other, the other end of the fourth resistor is connected to the emitter of the first transistor, the source of the MOS transistor is connected to the common end of the fourth resistor and the first transistor, the drain of the MOS transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the external 12V voltage terminal, the base of the second transistor is connected to the common end of the fifth resistor and the MOS transistor, the emitter of the second transistor is connected to the common end of the MOS transistor and the fourth resistor, the collector of the second transistor is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the external 12V voltage terminal, one end of the seventh resistor is connected to the common end of the sixth resistor and the second transistor, the other end of the seventh resistor is connected to the eighth resistor, the other end of the eighth resistor is connected to the output voltage switching switch unit, and the emitter of the second transistor is connected to the common end of the seventh resistor and the eighth resistor.

[0012] Further, the comparator control unit also includes a first capacitor, a second capacitor, a third capacitor and a voltage regulator diode, one end of the first capacitor is connected to the common end of the photoelectric coupler and the first resistor, the other end of the first capacitor is connected to the common end of the photoelectric coupler and the emitter of the first transistor, one end of the second capacitor is connected to the common end of the second resistor and the fourth resistor, the other end of the second capacitor is connected to the common end of the fourth resistor and the first transistor, one end of the third capacitor is connected to the emitter of the second transistor, the other end of the third capacitor is connected to the common end of the seventh resistor and the eighth resistor, one end of the voltage regulator diode is connected to the common end of the third capacitor and the second transistor, and the other end of the voltage regulator diode is connected to the common end of the third capacitor and the eighth resistor. The first capacitor, the second capacitor and the third capacitor are arranged in the comparator control unit to filter and protect the circuit, and the arrangement of the voltage regulator diode can ensure that the voltage output to the output voltage switching unit remains stable.

[0013] Furthermore, the output voltage switching switch unit includes a relay switch, one end of the electromagnet of the relay switch is grounded, the other end of the electromagnet is connected to the comparator control unit, the armature output end of the relay switch is provided with a lead-out end, the high voltage end of the relay is connected to the external high voltage input end, and the low voltage end of the relay is connected to the external low voltage input end.

[0014] The advantages of the present application are that the circuit structure is simple, wide voltage input is efficiently controlled, the input voltage range can be expanded, and the wider input voltage can increase the commonality of the product and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an input voltage widening circuit.

[0016] Figure 2 It is a schematic diagram of an existing circuit in a specific implementation manner.

[0017] Figure 3 yes Figure 2 The first part of the circuit diagram.

[0018] Figure 4 yes Figure 2 The second part of the circuit diagram.

[0019] Figure 5 yes Figure 2 The third part of the circuit diagram.

[0020] Figure 6 The invention discloses a schematic diagram of adding an input voltage widening circuit to an existing circuit diagram.

[0021] Figure 7 yes Figure 6 The first part of the circuit diagram.

[0022] Figure 8 yes Figure 7 The first part of the circuit diagram. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Reference Figure 1 .

[0025] An input voltage widening circuit is characterized in that it includes a voltage divider unit, a photoelectric coupling switch unit, a comparator control unit and an output voltage switching switch unit, an external power supply is connected to the input end of the voltage divider unit, the voltage divider unit, the photoelectric coupling switch unit, the comparator control unit and the output voltage switching switch unit are connected in sequence, and the output voltage switching switch unit is used to control the switching between an external high voltage input end and an external low voltage input end.

[0026] In this embodiment, the voltage divider unit includes a plurality of voltage divider resistors and a protection resistor R54, specifically R51, R52, R53 and R48. The voltage divider resistors R51, R52, R53 and R48 are connected in series in sequence. The input end of the voltage divider resistor R51 is connected to an external power supply, the output end of the voltage divider resistor R48 is connected to a photoelectric coupling switch unit, the input end of the protection resistor R54 is connected to the output end of the voltage divider resistor R48R, and the output end of the protected resistor R54 is grounded.

[0027] In this embodiment, the voltage divider unit also includes a filter capacitor C35, an input end of the filter capacitor C35 is connected to the common end of the voltage divider resistor and the photoelectric coupling switch unit, an output end of the filter capacitor C35 is connected to the common end of the protection resistor R54 and the ground terminal PGND, an input end of the protection resistor R54 is connected to the common end of the voltage divider resistor R48 and the filter capacitor C35, and the output of the protection resistor R54 is grounded PGND.

[0028] In this embodiment, the photoelectric coupling switch unit includes a controllable voltage regulator IC4 and a photoelectric coupler PC4, wherein PC4A and PC4B are the same photoelectric coupler, PC4A is the input end of the photoelectric coupler and the output end of the PC4B photoelectric coupler, the input end PC4A of the photoelectric coupler is connected to the cathode of the controllable voltage regulator IC4, the reference pole of the controllable voltage regulator IC4 is connected to the output end of the voltage divider resistor R48, the anode of the controllable voltage regulator IC4 is connected to the common end of the protection resistor R54 and the ground end PGND, and the output end PC4B of the photoelectric coupler is connected to the comparator control unit.

[0029] In this embodiment, the comparator control unit includes a first transistor Q8, a MOS transistor Q9, a second transistor Q10, a first resistor R101, a second resistor R59, a third resistor R102, a fourth resistor R40, a fifth resistor R103, a sixth resistor R104, a seventh resistor R120 and an eighth resistor R75; one end of the first resistor R101 is connected to the external 12V voltage end, the other end of the first resistor R101 is connected to one of the output ends of the photoelectric coupler PC4B, and the other output end of the photoelectric coupler PC4B is connected to the first transistor The emitter of the first transistor Q8 is connected, the base of the first transistor Q8 is connected to the common end of the first resistor R101 and the photoelectric coupler PC4B, the collector of the first transistor Q8 is connected to one end of the second resistor R59, the other end of the second resistor R59 is connected to one end of the third resistor R102, the other end of the third resistor R102 is connected to the common end of the first resistor R101 and the external 12V voltage end, the gate of the MOS tube Q9 is connected to the common end of the second resistor R59 and the third resistor R102, one end of the fourth resistor R40 is connected to the third resistor R102 is connected to the common end of the MOS tube Q9, the other end of the fourth resistor R40 is connected to the emitter of the first transistor Q8, the source of the MOS tube Q9 is connected to the common end of the fourth resistor R40 and the first transistor Q8, the drain of the MOS tube Q9 is connected to one end of the fifth resistor R103, the other end of the fifth resistor R103 is connected to the external 12V voltage end, the base of the second transistor Q10 is connected to the common end of the fifth resistor R103 and the MOS tube Q9, the emitter of the second transistor Q10 is connected to the MOS tube Q9 and the fourth resistor R40 is connected, the collector of the second triode Q10 is connected to one end of the sixth resistor R104, the other end of the sixth resistor R104 is connected to the external 12V voltage end, one end of the seventh resistor R120 is connected to the sixth resistor R104 and the common end of the second triode Q10, the other end of the seventh resistor R120 is connected to the eighth resistor R75, the other end of the eighth resistor R75 is connected to the output voltage switching switch unit, and the emitter of the second triode Q10 is connected to the common end of the seventh resistor R120 and the eighth resistor R75.

[0030] In this embodiment, the comparator control unit also includes a first capacitor C51, a second capacitor C44, a third capacitor C45 and a Zener diode ZD16, one end of the first capacitor C51 is connected to the common end of the photoelectric coupler PC4B and the first resistor R101, the other end of the first capacitor C51 is connected to the common end of the photoelectric coupler PC4B and the emitter of the first transistor Q8, one end of the second capacitor C44 is connected to the common end of the second resistor R59 and the fourth resistor R40, the other end of the second capacitor C44 is connected to the common end of the fourth resistor R40 and the first transistor Q8, one end of the third capacitor C45 is connected to the emitter of the second transistor Q10, the other end of the third capacitor C45 is connected to the common end of the seventh resistor R120 and the eighth resistor R75, one end of the Zener diode ZD16 is connected to the common end of the third capacitor C45 and the second transistor Q10, and the other end of the Zener diode ZD16 is connected to the common end of the third capacitor C45 and the eighth resistor R75.

[0031] In this embodiment, the output voltage switching switch unit includes a relay switch RY1, pin 1 of one end of the electromagnet of the relay switch RY1 is grounded, pin 2 of the other end of the electromagnet is connected to the comparator control unit, pin 3 of the armature output end of the relay switch is provided with a lead-out end, pin 4 of the high voltage end of the relay is connected to the external high voltage input end, and pin 5 of the low voltage end of the relay is connected to the external low voltage input end.

[0032] Reference Figure 2-5 , which is a circuit diagram commonly used in the prior art.

[0033] Reference Figure 6-8 , which is an application of the input voltage widening circuit in a specific embodiment, can expand the input voltage range from the original 12-16.8V to 12-30V.

[0034] The input end of the voltage-dividing resistor R51 is connected to the control power supply, and is connected to the transformer after passing through the input voltage widening circuit, wherein the coil turns ratio of the transformer's 8-pin and 10-pin is designed according to the input 12-15V low voltage, and the coil turns ratio of the 9-pin and 10-pin is designed according to the input 15-30V high voltage; BAT+ and BAT- are connected to the control power supply inlet, and OUTA and OUTB are connected to the input power supply inlet.

[0035] When the input voltage is in the low voltage range of 12-15V (it can be adjusted according to actual requirements), the voltage across R54 in the circuit is lower than 2.5V, so that PC4A is not conducting. Because PC4B (PC4B and PCB4A are the same optocoupler) is not conducting, Q8 is conducting and Q9 is off. Because Q9 is off, Q10 is conducting. Because Q10 is conducting, the power supply voltage of the relay switch RY1 is pulled down, so that the relay switch RY1 does not operate, then the 8th foot of the transformer is connected to the 3rd foot of the relay, and the output is within the safe design range; when the input voltage exceeds 15V, after the voltage of R54 reaches 2.5V after the voltage is divided by R51, R2, R53, R48 and R54, PC4A is conducting, so that PC4B is conducting, then Q8 is off, so that Q9 is conducting, Q9 is conducting and Q10 is off, so that 12V supplies power to the relay, so that the armature output terminal 3 pin of the relay switch RY1 is connected to the 9th foot of the transformer, so that the output voltage is within the controllable range.

[0036] The advantages of the present application are that the circuit structure is simple, wide voltage input is efficiently controlled, the input voltage range can be expanded, and the wider input voltage can increase the commonality of the product and reduce costs.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An input voltage widening circuit, characterized in that It includes a voltage dividing unit, a photoelectric coupling switch unit, a comparator control unit and an output voltage switching switch unit, an external power supply is connected to the input end of the voltage dividing unit, the voltage dividing unit, the photoelectric coupling switch unit, the comparator control unit and the output voltage switching switch unit are connected in sequence, and the output voltage switching switch unit is used to control the switching between the external high voltage input end and the external low voltage input end; The voltage dividing unit includes a plurality of voltage dividing resistors and a protection resistor, the plurality of voltage dividing resistors are sequentially connected in series, the input end of the voltage dividing resistor is connected to an external power supply, the output end of the voltage dividing resistor is connected to a photoelectric coupling switch unit, the input end of the protection resistor is connected to the output end of the voltage dividing resistor, and the output end of the protection resistor is grounded; The photoelectric coupling switch unit includes a controllable voltage regulator and a photoelectric coupler, the input end of the photoelectric coupler is connected to the cathode of the controllable voltage regulator, the reference electrode of the controllable voltage regulator is connected to the output end of the voltage divider resistor, the anode of the controllable voltage regulator is connected to the common end of the protection resistor and the ground end, and the output end of the photoelectric coupler is connected to the comparator control unit; The comparator control unit includes a first transistor, a MOS transistor, a second transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor; one end of the first resistor is connected to an external 12V voltage terminal, the other end of the first resistor is connected to one of the output ends of the photoelectric coupler, the other output end of the photoelectric coupler is connected to the emitter of the first transistor, the base of the first transistor is connected to the common end of the first resistor and the photoelectric coupler, the collector of the first transistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to the common end of the first resistor and the external 12V voltage terminal, the gate of the MOS tube is connected to the common end of the second resistor and the third resistor, and one end of the fourth resistor is connected to the common end of the third resistor and the MOS tube. The fourth resistor is connected to the emitter of the first transistor, the source of the MOS transistor is connected to the common end of the fourth resistor and the first transistor, the drain of the MOS transistor is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the external 12V voltage terminal, the base of the second transistor is connected to the common end of the fifth resistor and the MOS transistor, the emitter of the second transistor is connected to the common end of the MOS transistor and the fourth resistor, the collector of the second transistor is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the external 12V voltage terminal, one end of the seventh resistor is connected to the common end of the sixth resistor and the second transistor, the other end of the seventh resistor is connected to the eighth resistor, the other end of the eighth resistor is connected to the output voltage switching switch unit, and the emitter of the second transistor is connected to the common end of the seventh resistor and the eighth resistor.

2. An input voltage widening circuit as claimed in claim 1, characterized in that The voltage dividing unit further includes a filter capacitor, an input end of the filter capacitor is connected to a common end of the voltage dividing resistor and the protection resistor, and an output end of the filter capacitor is connected to a common end of the protection resistor and the grounding end.

3. The input voltage widening circuit according to claim 1, characterized in that The comparator control unit also includes a first capacitor, a second capacitor, a third capacitor and a zener diode, one end of the first capacitor is connected to the common end of the photoelectric coupler and the first resistor, the other end of the first capacitor is connected to the common end of the photoelectric coupler and the emitter of the first transistor, one end of the second capacitor is connected to the common end of the second resistor and the fourth resistor, the other end of the second capacitor is connected to the common end of the fourth resistor and the first transistor, one end of the third capacitor is connected to the emitter of the second transistor, the other end of the third capacitor is connected to the common end of the seventh resistor and the eighth resistor, one end of the zener diode is connected to the common end of the third capacitor and the second transistor, and the other end of the zener diode is connected to the common end of the third capacitor and the eighth resistor.

4. An input voltage widening circuit as claimed in claim 1, characterized in that The output voltage switching switch unit includes a relay switch, one end of the electromagnet of the relay switch is grounded, the other end of the electromagnet is connected to the comparator control unit, the armature output end of the relay switch is provided with a lead-out end, the high voltage end of the relay is connected to the external high voltage input end, and the low voltage end of the relay is connected to the external low voltage input end.

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