Constant current control circuit suitable for power supply parallel connection

Abstract

The application provides a constant current control circuit suitable for power supply parallel connection, solves the problem that the output current constant current value of a traditional redundant backup power supply system is far more than the rated demand current value of a load, thereby endangering system safety, and realizes that the output constant current total current of the redundant backup power supply system is the system constant current limiting value, rather than the sum of the constant current values of each power supply. When one power supply fails to exit the parallel connection state, the constant current point of the power supply still in the working state is automatically changed, the load current demand is ensured, and the reliability of the system is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of switching power supply, and particularly relates to a constant current control circuit. BACKGROUND

[0002] With the development of science and technology, electronic equipment urgently needs high safety, high reliability and large-capacity power supply, especially the use of large-power phased array radar, which puts forward higher and higher requirements on the performance of power supply. However, due to the limitations of the performance of power electronic devices, the saturation of magnetic components and other problems, multiple power supplies are often used in parallel in large-power power supply systems, which not only solves the problem of insufficient power supply capacity, but also realizes the parallel redundancy function, which can automatically exit operation when a power supply fails, thereby improving the reliability of the system.

[0003] The output current constant current function is an indispensable function in the large-power power supply of the radar array surface. This function can quickly pull down the output voltage to make the power supply in a constant current state when a large current occurs at the output end of the power supply. On the one hand, the safety of the power supply itself is ensured, and on the other hand, the further spread of the fault is prevented. The traditional power supply output constant current control circuit is shown in FIG. Figure 1 .

[0004] Figure 1 In the figure, the traditional power supply output constant current control circuit is composed of an operational amplifier, a resistance-capacitance network and a diode. The operational amplifier and the resistance-capacitance network constitute two negative feedback control circuits, one of which is used for output current limiting control, and the other of which is used for output voltage closed-loop voltage stabilization control. The diode is reversely connected at the output end of the front-end operational amplifier, and the anode of the diode is connected to the output voltage reference value voltage division point V oref . I o is the local output current feedback value, I ref is the local output constant current reference value, V ref is the local output voltage reference value, and V o is the local output voltage feedback value.

[0005] When the output current of the power supply is normal, the local output current feedback value I o is less than the voltage value at point 1, the output of the operational amplifier 1 is high, the diode D1 is reversely cut off, and the output voltage reference value voltage division point V oref is not affected, and the constant current function does not work at this time. When the output side of the power supply is abnormal and the output of the power supply is approximately in a short-circuit state, the output current feedback value I o is greater than the voltage value at point 1, the output of the operational amplifier 1 becomes low, the diode D1 is forwardly conducted, and then the output voltage reference value voltage division point V orefThe output voltage of the power supply decreases. According to Ohm's law, when the output voltage of the power supply decreases to a certain value, the output voltage and the output current are balanced, so that the output current is maintained at a constant current value. When the current limiting degree of the power supply is intensified, the output voltage is further decreased due to the negative feedback control, so that the maximum output current of the power supply is maintained at the current limiting value. When the current limiting state disappears, the potential automatically jumps back to the original value, and the current limiting state is eliminated. oref The potential automatically jumps back to the original value, and the current limiting state is eliminated.

[0006] The conventional power supply output constant current control circuit only controls the maximum output current of the local output current, and cannot be associated with other parallel power supplies. That is, each array surface power supply has a fixed constant current point, and when multiple power supplies are used in parallel, the total output current of the parallel system is far beyond the rated current demand, and the protection function is lost. When the redundant backup capacity is not large, this problem is not prominent, but if the redundant capacity is large, for example, one backup one, this problem is obvious, and the constant current output needs to be limited. SUMMARY

[0007] The application aims to realize a constant current control circuit suitable for parallel power supply, solve the problem that the output current constant value of the conventional redundant backup power supply system is far beyond the rated demand current value of the load, thereby endangering the safety of the system, and realize that the output constant current total current of the redundant backup power supply system is the system constant current limiting value, rather than the sum of the constant current values of each power supply. When one power supply fails to exit the parallel state, the constant current point of the power supply still in the working state will automatically change, ensuring the load current demand and improving the reliability of the system.

[0008] The application provides a constant current control circuit suitable for parallel power supply, which comprises an operational amplifier, a resistance-capacitance network and a diode. A first-stage operational amplifier Q3 and a resistance network constitute an adder circuit, a second-stage operational amplifier Q1, a resistance-capacitance network and a diode constitute a one-way output negative feedback network, and a third-stage operational amplifier Q2 and a resistance-capacitance network constitute a voltage closed-loop control negative feedback network. The circuit comprises resistors R1-R12, capacitors C1-C6, a diode D1 and operational amplifiers Q1-Q3. Among them, an output current signal I o1 , I o2 is connected with one end of resistors R9 and R10 respectively, the other ends of the resistors R9 and R10 are connected with the same-phase input end of the operational amplifier Q3; one end of a resistor R11 is connected with the ground, and the other end is connected with the opposite-phase input end of the Q3; one end of a resistor R12 is connected with the opposite-phase input end of the Q3, and the other end is connected with the output end of the Q3; one end of a resistor R1 is connected with the output end of the operational amplifier Q3, and the other end is connected with the opposite-phase input end of the operational amplifier Q1; a current limiting reference signal I refThe other end of the resistor R2 is connected with the non-inverting input terminal of the operational amplifier Q1; one end of the capacitor C1 is connected with the ground, and the other end is connected with the non-inverting input terminal of Q1; one end of the resistor R3 is connected with the ground, and the other end is connected with the non-inverting input terminal of Q1; one end of the resistor R4 is connected with the inverting input terminal of Q1, and the other end is connected with the capacitor C3, one end of the capacitor C3 is connected with R4, and the other end is connected with the output terminal of Q1; one end of the capacitor C2 is connected with the inverting input terminal of Q1, and the other end is connected with the output terminal of Q1; the cathode of the diode D1 is connected with the output terminal of Q1, and the anode of the diode D1 is connected with the non-inverting input terminal of Q2; the output voltage reference signal V ref The other end of the resistor R2 is connected with the non-inverting input terminal of the operational amplifier Q1; one end of the capacitor C1 is connected with the ground, and the other end is connected with the non-inverting input terminal of Q1; one end of the resistor R3 is connected with the ground, and the other end is connected with the non-inverting input terminal of Q1; one end of the resistor R4 is connected with the inverting input terminal of Q1, and the other end is connected with the capacitor C3, one end of the capacitor C3 is connected with R4, and the other end is connected with the output terminal of Q1; one end of the capacitor C2 is connected with the inverting input terminal of Q1, and the other end is connected with the output terminal of Q1; the cathode of the diode D1 is connected with the output terminal of Q1, and the anode of the diode D1 is connected with the non-inverting input terminal of Q2; the output voltage reference signal V o The other end of the resistor R2 is connected with the non-inverting input terminal of the operational amplifier Q1; one end of the capacitor C1 is connected with the ground, and the other end is connected with the non-inverting input terminal of Q1; one end of the resistor R3 is connected with the ground, and the other end is connected with the non-inverting input terminal of Q1; one end of the resistor R4 is connected with the inverting input terminal of Q1, and the other end is connected with the capacitor C3, one end of the capacitor C3 is connected with R4, and the other end is connected with the output terminal of Q1; one end of the capacitor C2 is connected with the inverting input terminal of Q1, and the other end is connected with the output terminal of Q1; the cathode of the diode D1 is connected with the output terminal of Q1, and the anode of the diode D1 is connected with the non-inverting input terminal of Q2; the output voltage reference signal V

[0009] A constant current control circuit suitable for parallel connection of power supply, the negative feedback network composed of the last two stages of operational amplifier has the same working principle as the traditional constant current control circuit of power supply output. The first stage is an adder, which sums the local output current signal and the output current signal of the parallel power supply, and the summed signal I o is input to the next stage of negative feedback circuit as the input signal. When the output current of the power supply system is normal, the output current feedback value I o is less than the voltage value of 1 point, the output of the operational amplifier 1 is high, the diode D1 is reverse cut-off, and the output voltage reference value voltage division point V oref is not affected, and the constant current function does not work at this time. When the output side of the power supply is abnormal, the output current feedback value I o is greater than the voltage value of 1 point, the output of the operational amplifier 1 becomes low, the diode D1 is forward biased, and then the output voltage reference value voltage division point V oref becomes low, and the output voltage of the power supply decreases. According to Ohm's law, when the output voltage of the power supply decreases to a certain value, the output voltage and the output current are balanced, so that the output current is maintained at a constant current value. When the current limiting degree of the power supply is aggravated, the output voltage will be further reduced due to the negative feedback control, so that the maximum output current of the power supply is maintained at the current limiting value. When the current limiting state disappears, V oref potential automatically jumps back to the original value, and the current limiting state is eliminated.

[0010] When a short circuit or other fault occurs at the output side of a parallel redundant backup power supply system, the output current limiting function of the power supply system is activated, keeping the output current at a limiting value. In a power supply system using a traditional constant current control circuit, the output current constant value will remain at the sum of the constant current values of each power supply. In a power supply system using a constant current circuit, the output current constant value will remain at the preset system constant current value, and there is no phenomenon of the system constant current value being significantly higher than the load current value.

[0011] When a fault occurs in one of the power supplies in a parallel redundant backup power supply system, the faulty power supply automatically exits, and the remaining power supplies in the parallel redundant backup power supply system can still output the required current of the system. When multiple power supplies are connected in parallel, the sum of the output current signals I o automatically becomes the sum of the output currents of the remaining power supplies, and after closed-loop regulation, each remaining power supply will increase the output current. Since the system limiting reference does not change, after the faulty power supply automatically exits, the system can still meet the power supply demand.

[0012] The beneficial effects of the present application are:

[0013] A constant current control circuit suitable for power supply parallel connection has the following advantages:

[0014] 1. The problem of excessive total limiting value in traditional limiting control circuits that cannot guarantee system safety is solved. Due to the need for backup redundancy, each power supply using a traditional limiting control circuit has an independent limiting value, resulting in a total limiting value that is much higher than the system demand and cannot meet the limiting protection demand. The output currents of power supplies using limiting control circuits are related to each other, ensuring that the limiting value set for each power supply is the limiting value of the system demand, thereby ensuring the safety and effectiveness of system limiting.

[0015] 2. The limiting function is achieved by controlling the output voltage reference, thereby eliminating the voltage overshoot when the power supply exits the limiting function. Compared with the current loop limiting method, the voltage loop limiting method can make the voltage switching more natural and eliminate problems such as oscillation and overshoot. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Traditional power supply output constant current control circuit diagram

[0017] Figure 2 Constant current control circuit diagram suitable for power supply parallel connection

[0018] Figure 3 Traditional power supply output constant current control circuit simulation model

[0019] Figure 4 Constant current control circuit simulation model suitable for power supply parallel connection

[0020] Figure 5 Simulation waveform of traditional power supply output constant current control circuit

[0021] Figure 6 Simulation waveform of a constant current control circuit suitable for parallel power supplies Detailed Implementation

[0022] The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0023] like Figure 2 The diagram shows a constant current control circuit suitable for parallel power supplies. The circuit includes an operational amplifier, a resistor-capacitor network, and diodes. The circuit includes resistors R1-R12, capacitors C1-C6, diode D1, and operational amplifiers Q1-Q3. The output current signal I... o1 I o2 Connect one end of resistors R9 and R10 respectively, and connect the other ends of resistors R9 and R10 to the non-inverting input of operational amplifier Q3; connect one end of resistor R11 to ground and the other end to the inverting input of Q3; connect one end of resistor R12 to the inverting input of Q3 and the other end to the output of Q3; connect one end of resistor R1 to the output of operational amplifier Q3 and the other end to the inverting input of operational amplifier Q1; current limiting reference signal I. ref One end of resistor R2 is connected to the non-inverting input of operational amplifier Q1; one end of capacitor C1 is connected to ground, and the other end is connected to the non-inverting input of Q1; one end of resistor R3 is connected to ground, and the other end is connected to the non-inverting input of Q1; one end of resistor R4 is connected to the inverting input of Q1, and the other end is connected to capacitor C3; one end of capacitor C3 is connected to R4, and the other end is connected to the output of Q1; one end of capacitor C2 is connected to the inverting input of Q1, and the other end is connected to the output of Q1; the cathode of diode D1 is connected to the output of Q1, and the anode of diode D1 is connected to the non-inverting input of Q2; the output voltage reference signal V... ref One end of resistor R6 is connected to the non-inverting input of Q2; one end of resistor R7 is connected to ground, and the other end is connected to the non-inverting input of Q2; one end of capacitor C4 is connected to ground, and the other end is connected to the non-inverting input of Q2; the output voltage feedback signal V... o Connect one end of R5 to the inverting input of Q2; connect one end of resistor R8 to the inverting input of Q2 and the other end to C6; connect one end of capacitor C6 to R8 and the other end to the output of Q2; connect one end of capacitor C5 to the inverting input of Q2 and the other end to the output of Q2; the output signal of Q2 is the power modulation signal.

[0024] Example 1:

[0025] For example, the power supply of a certain airborne radar using the present application: the power supply system is composed of two power supplies in parallel, with the function of parallel redundancy of "one spare one". Each power supply can output current of 230A, the total load demand current is 200A, the system current limit value is set at 230A, combined with the Figures 1-6 , the circuit designed according to the present application is described in detail. Here, several key parameters are given.

[0026] The constant current control circuit is shown in Figure 2 : wherein R1 is 5.1kΩ, R2 is 3kΩ, R3 is 2.4kΩ, R4 is 5.1kΩ, R5 is 5.1kΩ, R6 is 5.1kΩ, R7 is 5.1kΩ, R8 is 100kΩ, R9 is 10kΩ, R10 is 10kΩ, R11 is 10kΩ, R12 is 10kΩ; C1 is 0.1uF, C2 is 100pF, C3 is 4.7nF, C4 is 0.1uF, C5 is 150pF, C6 is 0.33uF; Q1, Q2, Q3 are operational amplifiers LM158, diode D1 is BAS21; V ref , I ref is 5V.

[0027] The first case is that the power supply system load appears to be approximately short-circuited, and the power supply enters the constant current state. As shown in Figure 6 , the output current of each power supply using the constant current circuit is quickly limited to about 115A after the circuit exits saturation, Figure 5 the power supply using the traditional constant current circuit cannot enter the constant current state, each power supply outputs 150A, and cannot play a constant current protection role.

[0028] The second case is that the fault disappears, and the power supply exits the constant current state. As shown in Figure 6 , the output current of each power supply using the constant current circuit returns to 100A after the fault state disappears, and the output voltage naturally transitions to 15V, without an overshoot state.

[0029] The third case is that one of the parallel power supplies fails, and the load is powered by a single power supply. As shown in Figure 6 , the output current of the power supply using the constant current circuit quickly decreases to 0A when one of the circuits fails, and at the same time, the output current of the other parallel power supply quickly increases from 100A to 200A, making up for the current that the failed power supply cannot output. The switching between power supplies is natural, and there are no system failure problems.

[0030] The above is only the best specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application.

[0031] The description herein of any aspect of the application is not meant to be limiting of that aspect of the application. For example, features of one aspect of the application can be interchanged with features of another aspect of the application.

Claims

1. A constant current control circuit suitable for power supply parallel connection, characterized in that, The circuit comprises an operational amplifier, a resistance-capacitance network, and a diode; a first-stage operational amplifier Q3 and a resistance network constitute an adder circuit, a second-stage operational amplifier Q1, a resistance-capacitance network, and a diode constitute a one-way output negative feedback network, and a third-stage operational amplifier Q2 and a resistance-capacitance network constitute a voltage closed-loop control negative feedback network; the circuit comprises resistors R1-R12, capacitors C1-C6, a diode D1, and operational amplifiers Q1-Q3; The adder circuit constituted by the first-stage operational amplifier Q3 and the resistance network comprises resistors R9, R10, R11, and R12, and an operational amplifier Q3; Output current signal I o1 , I o2 are connected with one end of resistors R9, R10 respectively, the other end of resistors R9, R10 is connected with the same-phase input end of operational amplifier Q3; one end of resistor R11 is connected with the ground, the other end is connected with the opposite-phase input end of Q3; one end of resistor R12 is connected with the opposite-phase input end of Q3, the other end is connected with the output end of Q3; The one-way output negative feedback network constituted by the second-stage operational amplifier Q1, a resistance-capacitance network, and a diode comprises resistors R1, R2, R3, and R4, an operational amplifier Q1, capacitors C1, C2, and C3, and a diode D1; One end of the resistor R1 is connected with the output end of the operational amplifier Q3, and the other end is connected with the inverting input end of the operational amplifier Q1; the current limiting reference signal I ref One end of the resistor R2 is connected with the resistor R1, and the other end is connected with the non-inverting input end of the operational amplifier Q1; one end of the capacitor C1 is connected with the ground, and the other end is connected with the non-inverting input end of Q1; one end of the resistor R3 is connected with the ground, and the other end is connected with the non-inverting input end of Q1; one end of the resistor R4 is connected with the inverting input end of Q1, and the other end is connected with the capacitor C3, one end of the capacitor C3 is connected with R4, and the other end is connected with the output end of Q1; one end of the capacitor C2 is connected with the inverting input end of Q1, and the other end is connected with the output end of Q1; the cathode of the diode D1 is connected with the output end of Q1, and the anode of the diode D1 is connected with the non-inverting input end of Q2; The voltage closed-loop control negative feedback network constituted by the third-stage operational amplifier Q2 and a resistance-capacitance network comprises resistors R5, R6, R7, and R8, an operational amplifier Q2, capacitors C4, C5, and C6; Output voltage reference signal V ref One end of resistor R6 is connected with the other end of resistor R6 connected with Q2 same phase input end; one end of resistor R7 is connected with ground, the other end is connected with Q2 same phase input end; one end of capacitor C4 is connected with ground, the other end is connected with Q2 same phase input end; output voltage feedback signal V o One end of R5 is connected with the other end of R5 connected with Q2 opposite phase input end; one end of resistor R8 is connected with Q2 opposite phase input end, the other end is connected with C6; one end of capacitor C6 is connected with R8, the other end is connected with Q2 output end; one end of capacitor C5 is connected with Q2 opposite phase input end, the other end is connected with Q2 output end; Q2 output end signal is power modulation signal.

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