Multi-channel output high-precision constant voltage power supply and control method thereof

Abstract

The present invention provides a multi-channel output high-precision constant voltage power supply, which includes: a power module, a transformer, a plurality of secondary rectifier circuits and a constant voltage control circuit, and the number of constant voltage control circuits is one less than the number of secondary rectifier circuits, the power module is connected to the input end of the transformer, the output end of the transformer is connected to the input end of each secondary rectifier circuit, the output of the first secondary rectifier circuit is used as the main power output, the feedback signal output end of the first secondary rectifier circuit is connected to the feedback signal input end of the power module; the output ends of the remaining secondary rectifier circuits are connected to the constant voltage control circuit as the corresponding secondary power output. The multi-channel output rectifier circuit of the present invention is a parallel combination, does not require secondary energy conversion, has high system efficiency and low loss; each output can be individually voltage controlled, has a wide range of applications, and realizes a low-cost, high-precision voltage control mode.

Description

Technical Field

[0001] This patent involves the field of display screen power supply with two or more outputs. It is a switching power supply control circuit with two or more outputs with high conversion efficiency and high constant voltage accuracy. Background Art

[0002] In the field of display power supply, two-way output or multi-way output refers to the direct output of two or more power supplies from one transformer. Due to the cross-influence of the load size of each channel, load changes will cause the second group of output voltages to change significantly, even exceeding the power supply specification requirements.

[0003] If you want each power supply to be able to stabilize the voltage with high precision, taking two outputs as an example, the following methods can be used at present: 1. Two independent constant voltage power supplies. 2. One is the main constant voltage power supply, and the second is obtained by stepping down the main power supply. 3. The second power supply is used for linear voltage regulation. 4. Use a series inductor choke to control the voltage.

[0004] The first method has the advantage that both outputs can maintain a constant voltage accurately and have high conversion efficiency; the disadvantage is the high cost.

[0005] The second method has the advantage that both outputs can maintain a constant voltage accurately; the disadvantage is that due to the existence of secondary constant voltage, it is difficult to select power supply materials for low-voltage and high-current power supplies, the cost is high, and the system conversion efficiency is low.

[0006] The third method has the advantage that both outputs can maintain constant voltage accurately. The disadvantage is that the power loss is large and the system conversion efficiency is low.

[0007] The fourth method has the advantage of high power efficiency; the disadvantage is that the second output voltage varies greatly and cannot be kept constant accurately. Summary of the invention

[0008] The purpose of the present invention is to innovate the design of a multi-channel output high-precision constant voltage power supply and a control method thereof in view of the shortcomings of the existing two-channel output circuit, with high conversion efficiency and low cost.

[0009] The technical solution of the present invention is:

[0010] The present invention provides a multi-channel output high-precision constant voltage power supply, which comprises: a power supply module, a transformer, a plurality of secondary rectifier circuits and a constant voltage control circuit, wherein the number of the constant voltage control circuits is one less than the number of the secondary rectifier circuits, the power supply module is connected to the input end of the transformer, the output end of the transformer is connected in parallel to the input ends of the secondary rectifier circuits, the output of the first secondary rectifier circuit is used as the main power output, the feedback signal output end of the first secondary rectifier circuit is connected to the feedback signal input end of the power supply module; the output ends of the remaining secondary rectifier circuits are connected to the constant voltage control circuit and then used as the corresponding secondary power outputs.

[0011] Furthermore, the power supply module adopts an AC-DC forward switching power supply or an AC-DC flyback switching power supply.

[0012] Furthermore, the constant voltage control circuit includes a MOS tube Q1, a totem pole drive circuit, an inductor L, an optocoupler U1, a comparator U2, a voltage regulator diode Z1, and resistors R1, R2, and R3. One output end of the transformer serves as a corresponding secondary power output Vo+, and the other output end is connected to the drain of the MOS tube Q1. The source of the MOS tube Q1 is connected in series with the inductor L and serves as a ground terminal of the corresponding secondary power output. The gate of the MOS tube Q1 serves as a control terminal and is connected to the output end of the totem pole drive circuit. The input end of the totem pole drive circuit is connected to the output end of the optocoupler U1, and the input end of the optocoupler U1 is connected to the output end of the comparator U2. The in-phase signal input end of the comparator U2 is connected to the voltage regulator diode Z1, and the voltage regulator diode Z1 and the resistor R1 are connected in series between the secondary power output Vo+ and the ground terminal. The inverting signal input end of the comparator U2 is a voltage dividing point of the resistors R2 and R3, and the resistors R2 and R3 are connected in series between the secondary power output Vo+ and the ground terminal for voltage division.

[0013] Furthermore, there are at least two secondary rectifier circuits.

[0014] Furthermore, the optical coupler U1 is a high-speed optical coupler, model 6N136.

[0015] A multi-channel output high-precision constant voltage power supply control method, the method comprising the following steps:

[0016] S1, the first secondary rectifier circuit feedback control power module connected to the main power output;

[0017] S2, the load condition of the main power supply output affects the output voltage Vo+ of each secondary power supply:

[0018] When the main power module output is overloaded, the output voltage Vo+ of each secondary power supply increases;

[0019] When the main power module output is lightly loaded, the output voltage Vo+ of each secondary power supply decreases;

[0020] S3, when the secondary power supply output voltage Vo+ increases, the voltage of the reverse input terminal V2 of the comparator U2 increases. When V2 is higher than the reference voltage V1 output by the voltage stabilizing diode Z1, the comparator outputs a low level to the input terminal of the optocoupler U1. The low level signal is fed back to the totem pole drive circuit through the optocoupler U1, and the totem pole drive circuit amplifies and drives the MOS tube Q1 to turn off, and the secondary power supply output voltage Vo+ decreases.

[0021] When the secondary power supply output voltage Vo+ decreases, the voltage of the reverse input terminal V2 of the comparator U2 decreases. When V2 is lower than the reference voltage V1 output by the voltage stabilizing diode Z1, the comparator outputs a high level to the input terminal of the optocoupler U1. The high level signal is fed back to the totem pole drive circuit through the optocoupler U1, and the totem pole drive circuit amplifies and drives the MOS tube Q1 to turn on, and the secondary power supply output voltage Vo+ increases.

[0022] This process is repeated until the output voltage Vo+ is dynamically balanced and stable.

[0023] Beneficial effects of the present invention:

[0024] The multi-channel output rectifier circuit of the present invention is a parallel combination, does not require secondary energy conversion, has high system efficiency and low loss.

[0025] Each output of the present invention can be independently voltage-controlled, has a wide application range, and has high system stability.

[0026] The primary power supply system of the present invention is a single system, which realizes a low-cost and high-precision voltage control mode.

[0027] The present invention is aimed at the display screen power supply industry, and multiple outputs are combined into a common anode (positive poles of the power supply are connected) or a common cathode (negative poles of the power supply are connected) power supply, which can meet the power supply wiring requirements of different types of display screens.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0030] Figure 1 A schematic diagram of the overall system is shown.

[0031] Figure 2 A circuit diagram of a constant voltage control circuit is shown. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0033] The present invention provides a multi-channel output high-precision constant voltage power supply, which comprises: a power supply module, a transformer, a plurality of secondary rectifier circuits and a constant voltage control circuit, wherein the number of the constant voltage control circuits is one less than the number of the secondary rectifier circuits, the power supply module is connected to the input end of the transformer, the output end of the transformer is connected in parallel to the input ends of the secondary rectifier circuits, the output of the first secondary rectifier circuit is used as the main power output, the feedback signal output end of the first secondary rectifier circuit is connected to the feedback signal input end of the power supply module; the output ends of the remaining secondary rectifier circuits are connected to the constant voltage control circuit and then used as the corresponding secondary power outputs.

[0034] In this embodiment, the power supply module adopts an AC-DC forward switching power supply or an AC-DC flyback switching power supply; the present invention takes the forward as an example and is also applicable to other power supply topology architectures.

[0035] Furthermore, the constant voltage control circuit includes a MOS tube Q1, a totem pole drive circuit, an inductor L, an optocoupler U1, a comparator U2, a voltage regulator diode Z1, and resistors R1, R2, and R3. One output end of the transformer serves as a corresponding secondary power output Vo+, and the other output end is connected to the drain of the MOS tube Q1. The source of the MOS tube Q1 is connected in series with the inductor L and serves as a ground terminal of the corresponding secondary power output. The gate of the MOS tube Q1 serves as a control terminal and is connected to the output end of the totem pole drive circuit. The input end of the totem pole drive circuit is connected to the output end of the optocoupler U1, and the input end of the optocoupler U1 is connected to the output end of the comparator U2. The in-phase signal input end of the comparator U2 is connected to the voltage regulator diode Z1, and the voltage regulator diode Z1 and the resistor R1 are connected in series between the secondary power output Vo+ and the ground terminal. The inverting signal input end of the comparator U2 is a voltage dividing point of the resistors R2 and R3, and the resistors R2 and R3 are connected in series between the secondary power output Vo+ and the ground terminal for voltage division.

[0036] Furthermore, there are at least two secondary rectifier circuits; the optocoupler U1 is a high-speed optocoupler of model 6N136.

[0037] When implemented specifically: the control method includes the following steps:

[0038] S1, the first secondary rectifier circuit feedback control power module connected to the main power output;

[0039] S2, the load condition of the main power supply output affects the output voltage Vo+ of each secondary power supply:

[0040] When the main power module output is overloaded, the output voltage Vo+ of each secondary power supply increases;

[0041] When the main power module output is lightly loaded, the output voltage Vo+ of each secondary power supply decreases;

[0042] S3, when the secondary power supply output voltage Vo+ increases, the voltage of the reverse input terminal V2 of the comparator U2 increases. When V2 is higher than the reference voltage V1 output by the voltage stabilizing diode Z1, the comparator outputs a low level to the input terminal of the optocoupler U1. The low level signal is fed back to the totem pole drive circuit through the optocoupler U1, and the totem pole drive circuit amplifies and drives the MOS tube Q1 to turn off, and the secondary power supply output voltage Vo+ decreases.

[0043] When the secondary power supply output voltage Vo+ decreases, the voltage of the reverse input terminal V2 of the comparator U2 decreases. When V2 is lower than the reference voltage V1 output by the voltage stabilizing diode Z1, the comparator outputs a high level to the input terminal of the optocoupler U1. The high level signal is fed back to the totem pole drive circuit through the optocoupler U1, and the totem pole drive circuit amplifies and drives the MOS tube Q1 to turn on, and the secondary power supply output voltage Vo+ increases.

[0044] This process is repeated until the output voltage Vo+ is dynamically balanced and stable.

[0045] In the present invention, the multi-channel output rectifier circuit is a parallel combination, does not require secondary energy conversion, has high system efficiency and low loss; each output channel can be independently voltage controlled, has a wide range of applications, high system stability, and realizes a low-cost, high-precision voltage control mode.

[0046] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A multi-channel high-precision constant voltage power supply, It is characterized in that The power supply comprises: a power supply module, a transformer, a plurality of secondary rectifier circuits and a constant voltage control circuit, wherein the number of the constant voltage control circuits is one less than the number of the secondary rectifier circuits, the power supply module is connected to the input end of the transformer, the output end of the transformer is connected in parallel to the input ends of the secondary rectifier circuits, the output of the first secondary rectifier circuit is used as the main power output, the feedback signal output end of the first secondary rectifier circuit is connected to the feedback signal input end of the power supply module; the output ends of the remaining secondary rectifier circuits are connected to the constant voltage control circuit and used as the corresponding secondary power outputs; The constant voltage control circuit includes a MOS tube Q1, a totem pole drive circuit, an inductor L, an optical coupler U1, a comparator U2, a voltage regulator diode Z1, and resistors R1, R2, and R3. One output end of the transformer serves as a corresponding secondary power output Vo+, and the other output end is connected to the drain of the MOS tube Q1. The source of the MOS tube Q1 is connected in series with the inductor L and serves as the grounding end of the corresponding secondary power output. The gate of the MOS tube Q1 serves as a control end and is connected to the output end of the totem pole drive circuit. The input end of the totem pole drive circuit is connected to the output end of the optical coupler U1, and the input end of the optical coupler U1 is connected to the output end of the comparator U2. The in-phase signal input end of the comparator U2 is connected to the voltage regulator diode Z1, and the voltage regulator diode Z1 and the resistor R1 are connected in series between the secondary power output Vo+ and the grounding end. The inverting signal input end of the comparator U2 is a voltage dividing point of the resistors R2 and R3, and the resistors R2 and R3 are connected in series between the secondary power output Vo+ and the grounding end for voltage division. The multi-channel output high-precision constant voltage power supply adopts the following control steps: S1, the first secondary rectifier circuit feedback control power module connected to the main power output; S2, the load condition of the main power supply output affects the output voltage Vo+ of each secondary power supply: When the main power module output is overloaded, the output voltage Vo+ of each secondary power supply increases; When the main power module output is lightly loaded, the output voltage Vo+ of each secondary power supply decreases; S3, when the secondary power supply output voltage Vo+ increases, the voltage of the reverse input terminal V2 of the comparator U2 increases. When V2 is higher than the reference voltage V1 output by the voltage stabilizing diode Z1, the comparator outputs a low level to the input terminal of the optocoupler U1. The low level signal is fed back to the totem pole drive circuit through the optocoupler U1, and the totem pole drive circuit amplifies and drives the MOS tube Q1 to turn off, and the secondary power supply output voltage Vo+ decreases. When the secondary power supply output voltage Vo+ decreases, the voltage of the reverse input terminal V2 of the comparator U2 decreases. When V2 is lower than the reference voltage V1 output by the voltage stabilizing diode Z1, the comparator outputs a high level to the input terminal of the optocoupler U1. The high level signal is fed back to the totem pole drive circuit through the optocoupler U1, and the totem pole drive circuit amplifies and drives the MOS tube Q1 to turn on, and the secondary power supply output voltage Vo+ increases. This process is repeated until the output voltage Vo+ is dynamically balanced and stable.

2. The multi-channel high-precision constant voltage power supply according to claim 1, It is characterized in that The power supply module adopts an AC-DC forward switching power supply or an AC-DC flyback switching power supply.

3. The multi-channel high-precision constant voltage power supply according to claim 1, It is characterized in that There are at least two secondary rectifier circuits.

4. The multi-output high-precision constant voltage power supply according to claim 1, It is characterized in that The optical coupler U1 is a high-speed optical coupler, model 6N136.

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