Linear voltage-stabilizing and current-sharing circuit

Abstract

The utility model discloses a linear voltage-stabilizing current-sharing circuit, which comprises a plurality of voltage-stabilizing constant-current circuits connected in parallel, each voltage-stabilizing constant-current circuit comprises an MOS tube, a sampling resistor and a control module, one end of each MOS tube is connected with the positive electrode end of a direct-current power supply, the other two ends of each MOS tube are respectively connected with the sampling resistor and the control module, and the control module is connected to the negative electrode end of the direct-current power supply. The sampling resistor is connected with the cathode end of the direct-current power supply through the load resistor and is also connected with the control module, and the control module comprises a current loop and a voltage loop. The purpose of stabilizing the output voltage is achieved through the voltage loop, the purpose of limiting the output current is achieved through the current loop, and the combined action of the current loop and the voltage loop can ensure the voltage-reduction current-limiting output of a single MOS tube. Therefore, when a plurality of MOS tubes are connected in parallel, the control circuit of the MOS tube only needs to ensure that the current of a single MOS tube does not exceed a set current value, and the current sharing effect of the plurality of MOS tubes can be achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of direct current power supply, specifically relates to a linear voltage stabilizing current sharing circuit. BACKGROUND

[0002] DC-DC converter is also called DC-DC power supply, which is a circuit or a mechanical and electrical device for power conversion. It can convert DC power into DC power (or approximate DC) of different voltages. Its power range can be from very small to very large, and it is widely used in electronic devices, communication devices and industrial control systems. DC-DC power supply can not only convert one DC voltage into another DC voltage, but also output stable DC voltage without being affected by input voltage fluctuation and load change.

[0003] However, in some cases where DC-DC power supply is used, voltage reduction regulation is required to prevent damage to the load caused by high voltage. Most voltage reduction DC-DC power supplies on the market use PWM control, but this brings problems such as large size and difficulty in electromagnetic compatibility. Therefore, metal-oxide semiconductor field effect transistors (MOS transistors) are often used for voltage reduction, also known as linear voltage stabilization. Because the linear region of MOS transistors is relatively narrow, it is difficult to make a large power linear voltage stabilizer, and it is difficult to achieve current sharing for each MOS transistor. Therefore, more MOS transistors are often used in parallel to achieve current sharing, but this will result in a larger size, which is not suitable for the current market. Therefore, there is an urgent need for a linear voltage stabilization current sharing circuit that is small in size and has strong practicality. SUMMARY

[0004] The content part of the utility model is used to introduce the concept in a simple form, which will be described in detail in the specific implementation part. The content part of the utility model is not intended to identify the key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0005] In view of the problems and deficiencies in the prior art, the utility model provides a linear voltage stabilization current sharing circuit, which mainly includes a voltage stabilization constant current circuit. The control module in the voltage stabilization constant current circuit can ensure the voltage reduction and current limiting output of a single MOS transistor. At the same time, multiple voltage stabilization constant current circuits are connected in parallel to realize current sharing, so that the overall size is small and the applicability is strong. To solve the problems raised in the background art.

[0006] In order to achieve the above object, the utility model provides the following technical scheme: including a plurality of parallel connection's constant current circuit, the constant current circuit includes MOS pipe, sampling resistance and control module, one end of the MOS pipe connects direct current power positive pole end, its other two ends are connected with sampling resistance and control module respectively, the control module is connected to direct current power negative pole end, the sampling resistance is connected with direct current power negative pole end through load resistance, and the sampling resistance is also connected with the control module, the control module also includes current loop and voltage loop; the MOS pipe is used for reducing the voltage of direct current power positive pole end and control module access, the sampling resistance is used for gathering the current and voltage in the circuit, the current loop and voltage loop are used for adjusting constant current and stable voltage respectively.

[0007] Preferably, the voltage loop includes a voltage dividing resistor, a first reference voltage source, and a first linear optocoupler, one end of the voltage dividing resistor is connected to the sampling resistor, the voltage dividing resistor is connected to the input terminal of the first reference voltage source, the output terminal of the first reference voltage source is connected to the input terminal of the first linear optocoupler, and the output terminal of the first linear optocoupler is connected to the MOS transistor and the direct current power negative pole end, respectively.

[0008] Preferably, the current loop includes a current amplifier, a second reference voltage source, and a second linear optocoupler, the input terminal of the current amplifier is connected to both ends of the sampling resistor, the output terminal of the current amplifier is connected to the input terminal of the second reference voltage source, the output terminal of the second reference voltage source is connected to the input terminal of the second linear optocoupler, and the second linear optocoupler is connected to the MOS transistor and the direct current power negative pole end, respectively.

[0009] Preferably, the first reference voltage source and the second reference voltage source are AZ431AN-ATRE1. The reference voltage source is AZ431AN-ATRE1 of the American Taiwan company, and the output voltage can be set between 2.5V and 36V, which makes it highly flexible in different application scenarios. The voltage reference error of this model reference source is only ±0.15%, which ensures the stability of the output, and it performs well in the full temperature range.

[0010] Preferably, the MOS transistor is NCEP023N10T. The MOS transistor is NCEP023N10T of Xintian New Clean Energy Company, NCEP023N10T is a power MOSFET composed of N-type semiconductor material and P-type semiconductor material, and the two layers of semiconductor material are separated by an insulating layer to control the electric field. When the voltage applied between the gate and the source increases, the accumulation of electrons in the oxide layer increases and the resistance decreases, resulting in greater current flow. Conversely, applying a smaller voltage will reduce the accumulation of electrons, increase the resistance and reduce the current.

[0011] Preferably, the current amplifier is the INA138NA / 3K model. The INA138NA / 3K current amplifier, manufactured by Texas Instruments, features a wide input common-mode voltage range and low quiescent current, and is designed for a wide range of applications in a small SOT-23 package. Its input common-mode and supply voltages are independent, with a voltage range of 2.7V to 36V, and a quiescent current of only 25μA, allowing the power supply to be connected to either side of the current measurement shunt with very low error.

[0012] Preferably, the first and second linear optocouplers are PC817C models. The PC817C linear optocoupler enables electrical isolation between the input and output terminals, effectively blocking electrical connections between circuits or systems. Furthermore, it has low input impedance while the impedance of interference sources is high, and it also features low power consumption, fast response speed, long service life, and small size.

[0013] Compared with the prior art, the beneficial effects provided by this utility model are:

[0014] This invention provides a linear voltage-regulating and current-sharing circuit with excellent voltage regulation and constant current performance, and a small size with strong applicability. It includes multiple parallel-connected voltage-regulating and constant-current circuits, each comprising a MOSFET, a sampling resistor, a load resistor, and a control module. The control module includes a voltage loop and a current loop. The voltage loop controls the voltage between the gate and source (GS) of the MOSFET when the output voltage exceeds a set voltage, utilizing the linear region of the MOSFET to change the voltage between the drain and source (DS), thereby changing the voltage at the load end and achieving output voltage stability. The current loop controls the voltage between the gate and source (GS) of the MOSFET when the output current exceeds a set current, utilizing the linear region of the MOSFET to change the voltage between the drain and source (DS), thereby changing the voltage at the load end. Based on Ohm's law, the load current is altered, thus limiting the output current. Therefore, when multiple MOSFETs are connected in parallel, the control circuit only needs to ensure that the current of a single MOSFET does not exceed a set current value, achieving the current-sharing effect of multiple MOSFETs in parallel. Attached Figure Description

[0015] Figure 1 This is a block diagram of a linear voltage regulator and current sharing circuit according to the present invention.

[0016] Figure 2 This is a circuit diagram of a linear voltage regulator and current sharing circuit according to the present invention.

[0017] Figure 3 This is a detailed implementation diagram of a linear voltage regulator and current sharing circuit according to this utility model. Detailed Implementation

[0018] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0019] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0020] Example

[0021] This embodiment provides a linear voltage regulator and current sharing circuit, referring to... Figure 1 As shown, this utility model includes multiple parallel-connected voltage-regulating and constant-current circuits. Each voltage-regulating and constant-current circuit includes a MOSFET, a sampling resistor, and a control module. One end of the MOSFET is connected to the positive terminal (DC+) of the DC power supply, and the other two ends are connected to the sampling resistor and the control module, respectively. The control module is connected to the negative terminal of the DC power supply. One end of the sampling resistor is connected to the negative terminal (DC-) of the DC power supply through a load resistor, and the sampling resistor is also connected to the control module. The MOSFET in the circuit is used to reduce the voltage connected to the positive terminal of the DC power supply and the control module. The sampling resistor is used to collect the current and voltage in the circuit. The control module is used to adjust the voltage and current. The load resistor is used to limit the current flowing through the circuit and, together with other components, determines the operating state of the circuit, ensuring that the current and voltage are within the required range.

[0022] Specifically, a MOSFET is a metal-oxide-semiconductor field-effect transistor. The drain (D) of MOSFET Q1 is connected to the positive terminal DC+ of the DC power supply, the source (S) of MOSFET Q1 is connected to one end of the sampling resistor R7, the gate (G) of MOSFET Q1 is connected to the power supply V1, and a load resistor R8 is connected in series between one end of the sampling resistor R7 and the negative terminal DC- of the DC power supply.

[0023] Reference Figure 2As shown, the control module includes a voltage loop and a current loop. The current loop includes resistors R3 and R2, a second reference voltage regulator U3, a second linear optocoupler U2, and a current amplifier U1. Resistors R2 and R3 are current-limiting resistors. The two ends of the sampling resistor R7 are connected to the positive and negative input terminals of the current amplifier U1, respectively. The output terminal of the current amplifier U1 is connected to the reference terminal R of the second reference voltage regulator U3. The anode A of the second reference voltage regulator U3 is connected to the negative terminal DC- of the DC power supply, and the cathode K of the second reference voltage regulator U3 is connected to the negative input terminal of the second linear optocoupler U2. The positive input terminal of the second linear optocoupler U2 is connected to the power supply V2 through resistor R3. The positive and negative output terminals of the second linear optocoupler U2 are connected to resistor R2 and the negative terminal DC- of the DC power supply, respectively. The other end of resistor R2 is then connected to the power supply V1.

[0024] The voltage loop includes resistors R4, R5, R6, and R1, a first reference voltage regulator U5, and a first linear optocoupler U4. Resistors R4 and R5 are voltage divider resistors, and resistors R1 and R6 are current-limiting resistors. One end of the sampling resistor R7 is connected in series with resistors R4 and R5, and the other end of resistor R5 is connected to the negative terminal of the DC power supply, DC-. Point M between resistors R4 and R5 is connected to the reference terminal R of the first reference voltage regulator U5. The anode A of the first reference voltage regulator U5 is connected to the negative terminal of the DC power supply, DC-, and the cathode K of the first reference voltage regulator U5 is connected to the negative input terminal of the first linear optocoupler U4. The positive input terminal of the first linear optocoupler U4 is connected in series with resistor R6 and then connected to power supply V2. The positive and negative output terminals of the first linear optocoupler U4 are connected to the negative terminal of the DC power supply, DC-, and resistor R1, respectively. The other end of resistor R1 is then connected to power supply V1.

[0025] When the output voltage exceeds the set voltage, the voltage loop controls and adjusts the voltage between the drain and source of the MOSFET, thereby changing the voltage at the output terminal of the load resistor. Conversely, when the output current exceeds the set current, the current loop controls the voltage between the gate and source of the MOSFET to control the voltage at the output terminal of the load resistor. According to Ohm's law, the load current is altered, thus limiting the output current. In particular, when the current loop and voltage loop work together, they can ensure the buck current-limiting output of a single MOSFET. However, when multiple MOSFETs are connected in parallel, their control circuits only need to ensure that the current of a single MOSFET does not exceed the set current value to achieve current sharing among the multiple MOSFETs in parallel.

[0026] Specific implementation effects

[0027] The following describes a high-power linear voltage regulator and current sharing circuit with two parallel outputs of 26V and 20A, designed according to this invention. Refer to the specific wiring diagram. Figure 3As shown, two parallel constant current and voltage regulator circuits are used, which means two MOSFETs are connected in parallel. The DC power supply is 28V, the MOSFET is NCEP023N10T from Wuxi Xinjieneng, the reference regulator is AZ431AN-ATRE1 from US-Taiwan, the current amplifier is INA138NA / 3K from Texas Instruments, the sampling resistor is 5mΩ, power supply V1 is 36V, power supply V2 is 5V, the load resistor is 2.6Ω, the voltage divider resistors are 23.5kΩ and 2.5kΩ respectively, the linear optocoupler is PC817C, and the current limiting resistors are all 5kΩ. For example, when the DC power supply input voltage is 28V, if the required output voltage is 26V, a 2V voltage drop is consumed by the MOSFET.

[0028] Voltage loop regulation stage. When the voltage at point M of the voltage divider resistor is higher than 2.5V, according to the voltage divider relationship, the output voltage is greater than (2.5 / 2.5k)*(2.5k+23.5k)=26V. The voltage is sampled and reduced by the voltage divider resistor, and the reduced voltage is input to the reference voltage regulator. At this time, since the reference voltage TL431 is 2.5V, when the voltage at the reference terminal R of the reference voltage regulator is higher than 2.5V, the current from the cathode K terminal to the anode A terminal of the reference voltage regulator will increase, resulting in an increase in the input current of the linear optocoupler. According to the principle of linear optocouplers, an increase in the input current of the linear optocoupler will also increase its output current. The output current of the linear optocoupler is then input to the MOSFET, which will reduce the gate and source voltages of the MOSFET, thereby increasing the drain and source voltages of the MOSFET, thus achieving the purpose of voltage regulation.

[0029] The current loop is a constant current stage. When the input current reaches 10A, the voltage across the sampling resistor is 10A * 5mΩ.

[0030] =50mV. If the current amplifier's gain is 50, the output of the current amplifier will be 50 * 50mV = 2.5V. When the current is greater than 10A, the output of the current amplifier will be greater than 2.5V. The output terminal of the current amplifier is connected to the reference terminal R of the reference voltage regulator. When the voltage at the reference terminal R of the reference voltage regulator is higher than 2.5V, the current from the cathode K terminal to the anode A terminal of the reference voltage regulator will increase. Similarly, the input current of the linear optocoupler will increase, and the output current of the linear optocoupler will also increase. The output current of the linear optocoupler is then input to the MOSFET. At this time, the gate (G) and source (S) voltages of the MOSFET decrease, thereby increasing the drain (D) and source (S) voltages of the MOSFET. According to Ohm's law, if the load resistance remains unchanged when the output voltage decreases, the output current will decrease, thus achieving the purpose of constant current.

[0031] In this embodiment, the current sharing stage uses two MOSFETs connected in parallel. However, in actual use, even if the same model of components is used, the differences in components will still lead to inconsistent output voltages between the two MOSFETs. For example, if MOSFET Q1 outputs 26.01V and MOSFET Q2 outputs 26.00V, when the load resistance requires 10A, according to circuit principles, MOSFET Q1 outputs 10A, and MOSFET Q2 outputs 0A. If the load resistance requirement is greater than 10A, and the current output of MOSFET Q1 increases further, it will cause the output voltage of MOSFET Q1 to drop below the voltage of MOSFET Q2. According to circuit principles, MOSFET Q2 will then start to draw current, thus achieving the current sharing effect.

[0032] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0033] Furthermore, in this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0034] The above are merely preferred embodiments of this utility model, and other embodiments are also possible. Those skilled in the art can still modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A linear voltage regulator and current sharing circuit, characterized in that: The system includes multiple parallel-connected voltage-regulating and constant-current circuits. Each voltage-regulating and constant-current circuit comprises a MOSFET, a sampling resistor, and a control module. One end of the MOSFET is connected to the positive terminal of a DC power supply, while the other two ends are connected to the sampling resistor and the control module, respectively. The control module is connected to the negative terminal of the DC power supply. The sampling resistor is connected to the negative terminal of the DC power supply through a load resistor and is also connected to the control module. The control module includes a current loop and a voltage loop. The MOSFET is used to reduce the voltage connected to the positive terminal of the DC power supply and the control module. The sampling resistor is used to collect the current and voltage in the circuit. The current loop and voltage loop are used to adjust the constant current and stabilize the voltage, respectively.

2. The linear voltage regulator and current sharing circuit according to claim 1, characterized in that: The voltage loop includes a voltage divider resistor, a first reference voltage regulator, and a first linear optocoupler. The voltage divider resistor is connected to one end of the sampling resistor and to the input terminal of the first reference voltage regulator. The output terminal of the first reference voltage regulator is connected to the input terminal of the first linear optocoupler, and the output terminal of the first linear optocoupler is then connected to the MOS transistor and the negative terminal of the DC power supply.

3. The linear voltage regulator and current sharing circuit according to claim 2, characterized in that: The current loop includes a current amplifier, a second reference voltage regulator, and a second linear optocoupler. The input terminal of the current amplifier is connected to both ends of the sampling resistor, the output terminal of the current amplifier is connected to the input terminal of the second reference voltage regulator, the output terminal of the second reference voltage regulator is connected to the input terminal of the second linear optocoupler, and the second linear optocoupler is then connected to the MOS transistor and the negative terminal of the DC power supply.

4. The linear voltage regulator and current sharing circuit according to claim 3, characterized in that: The first and second reference voltage regulators are model AZ431AN-ATRE1.

5. A linear voltage regulator and current sharing circuit according to claim 3, characterized in that: The MOSFET used is model NCEP023N10T.

6. A linear voltage regulator and current sharing circuit according to claim 3, characterized in that: The current amplifier used is model INA138NA / 3K.

7. A linear voltage regulator and current sharing circuit according to claim 3, characterized in that: The first and second linear optocouplers are of model PC817C.

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