Far-end voltage compensation circuit

Abstract

The utility model relates to the technical field of power electronics, and discloses a far-end voltage compensation circuit, which is characterized in that a voltage sampling circuit and a current sampling circuit respectively carry out sampling processing on output voltage and current of a power supply and then access a voltage compensation calculation circuit; the voltage compensation calculation circuit comprises an adder and a resistor, the output of the voltage compensation calculation circuit is connected to a pin at the anti-phase end of an error amplifier of the PWM controller, and a pin at the normal phase end of the error amplifier of the PWM controller is connected to a reference value voltage; and the PWM controller adjusts the output driving signal according to the output of the error amplifier, so that the Vo output near-end voltage is improved, and the far-end voltage compensation is realized. According to the utility model, a power supply output current sampling signal is directly introduced, and the PWM controller timely adjusts the near-end output voltage of the power supply according to the change of the output current by adjusting the parameters of the current sampling circuit and matching the resistance of the output cable, thereby ensuring the stability of the far-end voltage. The technical scheme of the utility model is strong in anti-interference performance and fast in response speed.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and particularly relates to a remote voltage compensation circuit for a high-power power supply. Background Art

[0002] In the application scenario of high-power power supplies, there will be a voltage drop due to the resistance of the power supply cable between the power supply and the load. As the load current increases, the voltage drop of the power supply cable will continuously increase. Especially when the cable is long, the voltage drop is even greater, resulting in a decrease in the voltage obtained by the remote load device. When the load device is sensitive to the input voltage, the voltage drop of the power supply cable will have a greater impact on the electrical equipment. To solve this problem, remote voltage compensation must be carried out. The existing remote compensation technical solutions generally sample the remote voltage to control the remote voltage value for compensation. The existing such technical solutions mainly have the following deficiencies: They require long remote voltage sampling cables, interfaces, etc., which increase the cost and are more vulnerable to interference, resulting in unstable power supply operation; in addition, the response speed is slow and cannot meet the requirements of high-frequency load changes. Summary of the Invention

[0003] The purpose of the utility model is to improve the remote voltage compensation circuit in view of the above deficiencies and provide a more perfect remote voltage compensation circuit. To achieve the above purpose, the technical solution of the utility model is as follows:

[0004] A remote voltage compensation circuit includes a voltage sampling circuit, a current sampling circuit, a PWM controller, voltage-dividing resistors R13 and R14. One end of resistor R13 is connected to the reference voltage pin VREF of the PWM, one end of resistor R14 is grounded, and the voltage-dividing node where resistor R13 and R14 are connected is connected to the non-inverting input pin EA+ of the error amplifier in the PWM controller. It also includes a voltage compensation calculation circuit. The voltage compensation calculation circuit includes an adder U1 and resistors R3, R10, R11, and R12. The output of the voltage sampling circuit is connected to the inverting input terminal of the adder through resistor R3; the output of the current sampling circuit is connected to the inverting input terminal of the adder through resistor R10, and resistor R11 is connected between the inverting input terminal and the output terminal of the adder; the output terminal of the adder is connected to the inverting input pin EA- of the error amplifier in the PWM controller through resistor R12.

[0005] Further, the voltage sampling circuit is an inverting proportional amplification circuit, which includes: an operational amplifier U2A, resistors R1 and R2. The inverting input terminal of the operational amplifier U2A is connected to the positive terminal of the output voltage signal Vo of the high-power power supply through resistor R1, the non-inverting input terminal of the operational amplifier U2A is grounded, and resistor R2 is connected between the inverting input terminal and the output terminal of the operational amplifier U2.

[0006] Further, the current sampling circuit includes a differential amplifier circuit and an inverting proportional amplifier circuit;

[0007] The differential amplifier circuit consists of an operational amplifier U3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7. Among them, the inverting input terminal of the operational amplifier U3 is connected to the positive terminal output by the output current signal sampling device of the high-power power supply through R4, and the non-inverting input terminal of the operational amplifier U3 is connected to the negative terminal output by the output current signal sampling device of the high-power power supply through the resistor R5; the resistor R6 is connected between the inverting input terminal and the output terminal of the operational amplifier U3, one end of the resistor R7 is connected to the non-inverting input terminal of the operational amplifier U3, and the other end is grounded;

[0008] The inverting proportional amplifier circuit consists of an operational amplifier U2B, a resistor R8, and a resistor R9. Among them, one end of the resistor R8 is connected to the output terminal of the operational amplifier U3 in the differential amplifier circuit, and the other end is connected to the inverting input terminal of U2B. The resistor R9 is connected between the inverting input terminal and the output terminal of the operational amplifier U2B.

[0009] Further, the output current signal sampling device of the high-power power supply is a shunt or a Hall sensor.

[0010] Further, the resistance values of the resistors R4 and R5 in the differential amplifier circuit are equal, and the resistance values of the resistors R6 and R7 are equal.

[0011] Further, the reverse input pin EA- of the error amplifier in the PWM controller is also connected to the output pin E / AOUT of the error amplifier in the PWM controller through an RC compensation network.

[0012] Advantages of the present utility model

[0013] The present utility model directly introduces the output current sampling signal of the power supply and conducts control. By adjusting the parameters of the power supply output current sampling circuit, the output cable resistance is matched, and the output voltage at the near end of the power supply is adjusted in a timely manner according to the change of the output current, ensuring the stability of the voltage at the far end. Compared with the prior art, the voltage sampling cable, interface, etc. at the far end side are cancelled, reducing the cost and having strong anti-interference ability; in addition, the response speed is fast, which is suitable for the load change requirements of high frequency. Description of the drawings

[0014] Figure 1 It is the circuit schematic diagram of the embodiment of the present utility model. Detailed implementation manners

[0015] In order to make the objectives, technical solutions and advantages of the present utility model more clear and understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. In addition, the technical features involved in the various embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0016] The following Figure 1 illustrates the working principle of the present utility model with reference to the

[0017] In an embodiment of a remote voltage compensation circuit of the present utility model, it includes a voltage sampling circuit, a current sampling circuit, a PWM controller, voltage-dividing resistors R13 and R14. One end of resistor R13 is connected to the reference voltage pin VREF of the PWM, one end of resistor R14 is grounded, the reference voltage of the PWM controller is 5V, and the resistances of resistors R13 and R14 are equal. After 1:1 voltage division, 2.5V is obtained and connected to the non-inverting input terminal EA+ of the error amplifier in the PWM controller. It also includes a voltage compensation calculation circuit, and the voltage compensation calculation circuit includes an adder U1 and resistors R3, R10, R11, and R12;

[0018] The voltage sampling circuit is an inverting proportional amplification circuit, including an operational amplifier U2A, resistors R1 and R2. The inverting input terminal of the operational amplifier U2A is connected to the positive terminal of the output voltage signal Vo of the high-power power supply through resistor R1, the non-inverting input terminal of the operational amplifier U2A is grounded, and resistor R2 is connected between the inverting input terminal and the output terminal of the operational amplifier U2; the output voltage of the operational amplifier U2A in the voltage sampling circuit is denoted as V V , V V = - (R2 / R1) * Vo;

[0019] The output voltage V V of the operational amplifier U2A in the voltage sampling circuit is connected to one end of resistor R3 in the voltage compensation calculation circuit, and the other end of resistor R3 is connected to the inverting input terminal of the adder U1 in the voltage compensation calculation circuit;

[0020] The current sampling circuit includes a differential amplification circuit and an inverting proportional amplification circuit;

[0021] Among them, the differential amplifier circuit consists of operational amplifier U3, resistor R4, resistor R5, resistor R6 and resistor R7. The inverting input terminal of operational amplifier U3 is connected to the positive terminal Iout+ of the shunt that samples the output current signal of the high-power power supply through resistor R4, and the non-inverting input terminal of operational amplifier U3 is connected to the negative terminal Iout- of the shunt that samples the output current signal of the high-power power supply through resistor R5; Resistor R6 is connected between the inverting input terminal and the output terminal of operational amplifier U3, one end of resistor R7 is connected to the non-inverting input terminal of operational amplifier U3, and the other end is grounded; The resistance values of resistor R4 and resistor R5 are equal, and the resistance values of resistor R6 and resistor R7 are equal. The amplification factor of the differential amplifier circuit is -R6 / R4.

[0022] The inverting proportional amplifier circuit consists of operational amplifier U2B, resistor R8 and resistor R9. Among them, one end of resistor R8 is connected to the output terminal of operational amplifier U3 in the differential amplifier circuit, and the other end is connected to the inverting input terminal of U2B. Resistor R9 is connected between the inverting input terminal and the output terminal of operational amplifier U2B; The amplification factor of the inverting proportional amplifier circuit is -R9 / R8.

[0023] The output voltage of operational amplifier U2B is the output of the current sampling circuit, denoted as V i , then V i = (R6 * R9 / R4 * R8) * I O , I o is the voltage difference between the two ends of the shunt that samples the output current signal of the high-power power supply, that is, the analog quantity of the voltage signal corresponding to the output current sampling.

[0024] The output voltage Vi of operational amplifier U2B of the current sampling circuit is connected to one end of resistor R10 of the voltage compensation calculation circuit, and the other end of resistor R10 is connected to the inverting input terminal of adder U1 of the voltage compensation calculation circuit; Resistor R11 is connected between the inverting input terminals of adder U1,

[0025] V V and V i are respectively connected to adder U1 through the inverting terminals of resistor R3 and resistor R10, and the output voltage is denoted as V. Then V = (R2 / R1) * Vo * (R11 / R3) - (R6 * R9 / R4 * R8) * I O * (R11 / R10);

[0026] The output voltage V of adder U1 is connected to the inverting pin EA- of the error amplifier of the PWM controller. Since the non-inverting pin EA+ of the error amplifier is 2.5V, the PWM controller adjusts the output drive signal to ensure that the voltage of the inverting pin EA- of the error amplifier is 2.5V. Therefore, when I OWhen it increases, that is, when the output current increases, the PWM controller adjusts the output drive signal to increase the voltage of the proximal output Vo, so as to ensure that the output voltage of the adder U1 is also 2.5V, thereby realizing remote voltage compensation. It should be noted that the PWM controller mentioned in this solution is an existing resonant controller chip or DSP processor chip (such as UC1875, UCC28950, etc.). The relevant programs burned in the chip to make the PWM controller adjust the output drive signal are also existing programs, which will not be elaborated here.

[0027] When the load is no-load, the output current sampling circuit outputs I o which is 0V. The output voltage of the high-power power supply is inverted by the voltage sampling circuit and the output value is negative. The adder U1 outputs a positive value in the reverse direction, that is, the output value V of the adder is (R2 / R1)*Vo*(R11 / R3). Then the voltage value connected to the inverting pin EA- of the error amplifier of the PWM controller increases. The PWM controller adjusts the output drive signal to decrease the output voltage until the output of the adder (R2 / R1)*Vo*(R11 / R3) decreases to 2.5V, and the output voltage is stabilized.

[0028] After loading, the output current increases. The output current of the power supply is processed by the sampling circuit and output as a positive value, which enters the inverting input terminal of the adder U1 together with the output of the output voltage sampling circuit. Then the output value V of the adder U1 = (R2 / R1)*Vo*(R11 / R3) - (R6*R9 / R4*R8)*I O *(R11 / R10) decreases, that is, the voltage value connected to the inverting pin EA- of the error amplifier of the PWM controller decreases. When it is less than 2.5V, the PWM controller adjusts the output drive signal to increase the output voltage so that the output of the adder remains 2.5V.

[0029] In the remote voltage compensation circuit of the present invention, the output value V of the adder U1 is associated with the voltage value Vo output by the high-power power supply and the analog quantity IO of the voltage signal corresponding to the output current sampling, and satisfies the relationship V = (R2 / R1)*Vo*(R11 / R3) - (R6*R9 / R4*R8)*IO*(R11 / R10). Therefore, the output voltage can be adjusted according to the output current of the high-power power supply. The specific adjustment amount can be based on the actual cable voltage drop. By adjusting the resistance value of the resistor R10 connected between the output end of the current sampling circuit and the inverting end of the adder U1, the increase in the output voltage is made consistent with the actual cable voltage drop, thereby realizing remote voltage compensation. Since the adjustment speed is very fast, when the switching power supply is working normally, the voltage of EA- can be regarded as a stable value of 2.5V. An RC compensation network is also connected between the inverting input pin EA- and the output pin E / AOUT of the error amplifier in the PWM controller to make the PWM controller work stably.

[0030] The above are only the preferred embodiments of the present utility model. It should be noted that due to the limitations of literal expression and objectively there are infinite specific structures. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the utility model to other occasions without improvement, shall all be regarded as the protection scope of the present utility model.

Claims

1. A remote voltage compensation circuit, comprising a voltage sampling circuit, a current sampling circuit, a PWM controller, voltage-dividing resistors R13 and R14. One end of resistor R13 is connected to the reference voltage pin VREF of the PWM, one end of resistor R14 is grounded, and the voltage-dividing node where resistor R13 and R14 are connected is connected to the non-inverting input pin EA+ of the error amplifier inside the controller of the PWM controller. It is characterized in that: It further includes a voltage compensation calculation circuit, which includes an adder U1 and resistors R3, R10, R11, and R12. The output of the voltage sampling circuit is connected to the inverting input terminal of the adder U1 through the resistor R3; the output of the current sampling circuit is connected to the inverting input terminal of the adder through the resistor R10, and the resistor R11 is connected between the inverting input terminal and the output terminal of the adder; the output terminal of the adder U1 is connected to the inverting input pin EA- of the error amplifier in the PWM controller through the resistor R12.

2. The remote voltage compensation circuit according to claim 1, wherein The voltage sampling circuit is an inverting proportional amplification circuit, which includes: an operational amplifier U2A, resistors R1 and R2. The inverting input terminal of the operational amplifier U2A is connected to the positive terminal of the output voltage signal Vo of the high-power power supply through the resistor R1, the non-inverting input terminal of the operational amplifier U2A is grounded, and the resistor R2 is connected between the inverting input terminal and the output terminal of the operational amplifier U2.

3. The remote voltage compensation circuit according to claim 1, wherein: The current sampling circuit includes a differential amplification circuit and an inverting proportional amplification circuit; The differential amplification circuit is composed of an operational amplifier U3, resistors R4, R5, R6, and R7. Among them, the inverting input terminal of the operational amplifier U3 is connected to the positive terminal of the output of the output current signal sampling device of the high-power power supply through R4, and the non-inverting input terminal of the operational amplifier U3 is connected to the negative terminal of the output of the output current signal sampling device of the high-power power supply through R5; the resistor R6 is connected between the inverting input terminal and the output terminal of the operational amplifier U3, and one end of the resistor R7 is connected to the non-inverting input terminal of the operational amplifier U3, and the other end is grounded; The inverting proportional amplification circuit is composed of an operational amplifier U2B and resistors R8 and R9. Among them, one end of the resistor R8 is connected to the output terminal of the operational amplifier U3 in the differential amplification circuit, and the other end is connected to the inverting input terminal of the operational amplifier U2B, and the resistor R9 is connected between the inverting input terminal and the output terminal of the operational amplifier U2B.

4. The remote voltage compensation circuit according to claim 3, wherein: The output current signal sampling device of the high-power power supply is a shunt or a Hall sensor.

5. The remote voltage compensation circuit according to claim 3, characterized in that: The resistance values of the resistors R4 and R5 in the differential amplification circuit are equal, and the resistance values of the resistors R6 and R7 are equal.

6. The remote voltage compensation circuit according to claim 1, wherein: The inverting input pin EA- of the error amplifier in the PWM controller is also connected to the output pin E / AOUT of the error amplifier in the PWM controller through an RC compensation network.

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