Current sharing circuit formed by operational amplifiers

Abstract

The utility model discloses a current sharing circuit formed by operational amplifiers, and aims to solve the problem of current sharing among modules in a power supply system and the problem of abnormal current sharing of power supplies of other modules in the power supply system or shutdown of a whole machine system when a current sharing bus is short-circuited or any power supply module connected to the bus fails after the current sharing of the power supply system. The utility model discloses a current sharing circuit formed by operational amplifiers, which comprises an in-phase proportion operational amplifier circuit, a bias voltage circuit, a voltage error amplifier circuit, an output protection circuit and a passive filter circuit so as to form a load current sharing circuit of a module power supply. Two operational amplifiers and one MOS tube are used to solve the problem of current sharing of the module power supply and the problem of system stability after current sharing.

Description

Technical Field

[0001] The utility model relates to the technical field of DC / DC converters, in particular to a current-sharing circuit formed by an operational amplifier. Background Art

[0002] DC / DC module power supply is the basic unit in the whole system, and it is also an essential unit, and it is widely used. With the vigorous development of military and civilian industries, the market demand for DC / DC module power supply continues to grow, especially the market demand for thin, modular, and standardized DC / DC module power supply with high efficiency, high power density, high current, low noise, and good dynamic characteristics.

[0003] As the module power supply market matures, some ultra-high power module power supplies are becoming more and more popular with customers. However, in some low-voltage and high-power applications, a single module power supply can no longer meet the load power requirements and needs to be considered in parallel. Using multiple medium / low power power supplies in parallel can not only meet the load power requirements and reduce pressure, but also apply redundancy technology to improve system reliability. Module power supply current balancing technology ensures the uniform distribution of current stress and thermal stress between modules and prevents one or more modules from operating in a current limiting state. It ensures that the output current of the entire system is evenly distributed according to the output capacity of each unit through sampling and electronic control regulation loops, so as to fully utilize the output capacity of each unit and ensure that each unit works reliably and stably.

[0004] The commonly used current balancing methods at this stage are: (1) output impedance method (2) master-slave control method (3) average current type automatic load current balancing method (4) maximum current automatic current balancing method (5) external circuit control method, etc. Each current balancing method has its own advantages and disadvantages. The utility model only involves the average current type automatic load current balancing method. Its main disadvantage is that when the current balancing bus is short-circuited or any power supply module connected to the bus fails, the error voltage changes, which can easily cause abnormal current balancing of other modules or shutdown of the entire system. Utility Model Content

[0005] In order to solve the current sharing problem between modules in the power supply system and the problem that when the current sharing bus is short-circuited or any power module connected to the bus fails, the power current sharing of other modules in the power supply system may be abnormal or the whole system may shut down.

[0006] The technical solution of the utility model is: a current balancing circuit composed of an operational amplifier, comprising a current sampling terminal CS, the current sampling terminal CS is connected to one end of a resistor R1, the other end of the resistor R1 is respectively connected to a capacitor C2, a resistor R2, and a non-inverting input end of an operational amplifier U1, the other end of the capacitor C2 is connected to a reverse input end of the operational amplifier U1, a resistor R3, a resistor R5, and one end of the capacitor C3, the other end of the resistor R2 is connected to the capacitor C1, and the other end of the capacitor C1 is grounded;

[0007] The other ends of the resistor R5 and the capacitor C3 are connected to the output end of the operational amplifier U1, the resistor R4, and the resistor R7 respectively; the other end of the resistor R4 is connected to the anode of the diode D1, the resistor R8, and the source of the MOS tube Q1; the cathode of the diode D1 is connected to the capacitor C1 and the resistor R2;

[0008] The other end of the resistor R7 is connected to the resistor R6, the capacitor C5 and the reverse input end of the operational amplifier U2, the other end of the resistor R6 is connected to a 5V voltage source, the other end of the capacitor C5 is connected to the resistor R10, the other end of the resistor R10 is connected to the output end of the operational amplifier U2 and the resistor R11, the positive input end of the operational amplifier U2 is connected to the resistor R8 and the capacitor C4, the other end of the capacitor C4 is grounded, the other end of the resistor R11 is connected to the anode of the photoelectric coupler light-emitting tube U3, and the cathode of the photoelectric coupler light-emitting tube U3 is grounded;

[0009] The drain of the MOS transistor Q1 is connected to the resistor R9, the capacitor C6 and the current sharing terminal SHARE, and the other ends of the resistor R9 and the capacitor C6 are grounded.

[0010] The resistor R1 , the resistor R2 , the resistor R3 , the resistor R5 , the capacitor C1 , the capacitor C2 , and the capacitor C3 constitute an in-phase proportional operation circuit.

[0011] The 5V voltage source and the resistor R6 form a bias voltage circuit.

[0012] The resistor R7, the resistor R8, the resistor R10, the capacitor C5 and the operational amplifier U2 form a voltage error amplification circuit.

[0013] The resistor R9 and the capacitor C6 form a filter circuit.

[0014] The gate of the MOS tube Q1 is connected to the control power supply VCC to form an output protection circuit.

[0015] The utility model has the following beneficial effects:

[0016] 1. The utility model uses a common-phase proportional operation circuit, a bias voltage circuit, a voltage error amplifier circuit, an output protection circuit, and an output filter circuit to complete a current-sharing circuit of a DC / DC module power supply.

[0017] 2. When any power module of the utility model circuit fails, the module will automatically disconnect from the power current sharing bus without affecting the normal operation of other power modules and the power system.

[0018] 3. The circuit design of the utility model is ingenious and simple, with high current sharing, and can realize automatic current sharing of module power supply without adding any circuit outside the power supply, which has a good promotion space in DC / DC converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the circuit principle of ordinary automatic load current balancing technology.

[0020] Figure 2 It is a circuit schematic diagram of the utility model. DETAILED DESCRIPTION

[0021] The following is combined with Figure 1 , 2 The utility model is described in detail as follows:

[0022] A current balancing circuit formed by an operational amplifier, comprising a current sampling terminal CS, wherein the current sampling terminal CS is connected to one end of a resistor R1, the other end of the resistor R1 is respectively connected to a capacitor C2, a resistor R2, and a non-inverting input end of an operational amplifier U1, the other end of the capacitor C2 is connected to a reverse input end of the operational amplifier U1, a resistor R3, a resistor R5, and one end of the capacitor C3, the other end of the resistor R2 is connected to a capacitor C1, and the other end of the capacitor C1 is grounded;

[0023] The other ends of the resistor R5 and the capacitor C3 are connected to the output end of the operational amplifier U1, the resistor R4, and the resistor R7 respectively; the other end of the resistor R4 is connected to the anode of the diode D1, the resistor R8, and the source of the MOS tube Q1; the cathode of the diode D1 is connected to the capacitor C1 and the resistor R2;

[0024] The other end of the resistor R7 is connected to the resistor R6, the capacitor C5 and the reverse input end of the operational amplifier U2, the other end of the resistor R6 is connected to a 5V voltage source, the other end of the capacitor C5 is connected to the resistor R10, the other end of the resistor R10 is connected to the output end of the operational amplifier U2 and the resistor R11, the positive input end of the operational amplifier U2 is connected to the resistor R8 and the capacitor C4, the other end of the capacitor C4 is grounded, the other end of the resistor R11 is connected to the anode of the photoelectric coupler light-emitting tube U3, and the cathode of the photoelectric coupler light-emitting tube U3 is grounded;

[0025] The drain of the MOS transistor Q1 is connected to the resistor R9, the capacitor C6 and the current sharing terminal SHARE, and the other ends of the resistor R9 and the capacitor C6 are grounded.

[0026] The resistor R1 , the resistor R2 , the resistor R3 , the resistor R5 , the capacitor C1 , the capacitor C2 , and the capacitor C3 constitute an in-phase proportional operation circuit.

[0027] The 5V voltage source and the resistor R6 form a bias voltage circuit.

[0028] The resistor R7, the resistor R8, the resistor R10, the capacitor C5 and the operational amplifier U2 form a voltage error amplification circuit.

[0029] The resistor R9 and the capacitor C6 form a filter circuit.

[0030] The gate of the MOS tube Q1 is connected to the control power supply VCC to form an output protection circuit.

[0031] The working principle of the utility model is:

[0032] The average current type automatic current balancing method is controlled by a bus passing through several power modules in the power supply system. The bus serves as a signal line to realize current balancing control. The voltage value of the control line is the average of the output current sampling voltage signals of each power module in the system. Each module will compare its own sampling voltage with the average of the current sampling voltage signal to obtain an error voltage. According to the error voltage of each module, the output current of the power module is adjusted to finally achieve the purpose of current balancing.

[0033] Specifically Figure 2 Explanation: The VCSO voltage amplitude represents the size of the output voltage of a single module, and the I-BUS voltage amplitude represents the average voltage of the output voltage signal of each power module. The op amp U1 performs in-phase proportional amplification on the voltage sampled by CS and transmits it in two ways, one of which is transmitted to the system current sharing bus, and the other is formed by R6 and 5VREF to form a bias voltage circuit and I-BUS through U2 to amplify the error voltage. When VCSO < I-BUS, the output voltage of the op amp U2 increases, and the light of the optocoupler U3 is enhanced, thereby making the COMP voltage of PWM higher and the duty cycle larger. The output voltage of a single module increases, and the output current of this module increases. Vice versa, the system current sharing is completed. When any of the power modules fails, the control gate of the MOS tube Q1 and the power supply voltage of the integrated circuits U1 and U2 become low level, the current sharing terminal of the power supply of this module will be separated from the current sharing bus, and the integrated circuits U1 and U2 will also stop working, without affecting the normal operation of other power modules and the power system.

[0034] The utility model discloses a current balancing circuit composed of an operational amplifier. The circuit uses a common-phase proportional operational amplifier circuit, a bias voltage circuit, a voltage error amplifier circuit, an output protection circuit and a passive filter circuit to complete automatic load current balancing of a module power supply and solve the problems that arise in the circuit application of the automatic load current balancing technology.

[0035] A current balancing circuit composed of an operational amplifier. The utility model has a simple circuit design, can realize automatic current balancing of module power supplies and solve the problems that arise in the circuit application of automatic load current balancing technology. The current balancing circuit has a simple design and high current balancing degree. When any power module fails, the module will automatically disconnect from the power balancing busbar without affecting the normal operation of other power modules and the system.

[0036] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a technician familiar with the field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A current sharing circuit formed by an operational amplifier, characterized in that: It includes a current sampling terminal CS, the current sampling terminal CS is connected to one end of a resistor R1, the other end of the resistor R1 is respectively connected to a capacitor C2, a resistor R2, and a non-inverting input end of an operational amplifier U1, the other end of the capacitor C2 is connected to a reverse input end of the operational amplifier U1, a resistor R3, a resistor R5, and one end of the capacitor C3, the other end of the resistor R2 is connected to the capacitor C1, and the other end of the capacitor C1 is grounded; The other ends of the resistor R5 and the capacitor C3 are connected to the output end of the operational amplifier U1, the resistor R4, and the resistor R7 respectively; the other end of the resistor R4 is connected to the anode of the diode D1, the resistor R8, and the source of the MOS tube Q1; the cathode of the diode D1 is connected to the capacitor C1 and the resistor R2; The other end of the resistor R7 is connected to the resistor R6, the capacitor C5 and the reverse input end of the operational amplifier U2, the other end of the resistor R6 is connected to a 5V voltage source, the other end of the capacitor C5 is connected to the resistor R10, the other end of the resistor R10 is connected to the output end of the operational amplifier U2 and the resistor R11, the positive input end of the operational amplifier U2 is connected to the resistor R8 and the capacitor C4, the other end of the capacitor C4 is grounded, the other end of the resistor R11 is connected to the anode of the photoelectric coupler light-emitting tube U3, and the cathode of the photoelectric coupler light-emitting tube U3 is grounded; The drain of the MOS transistor Q1 is connected to the resistor R9, the capacitor C6 and the current sharing terminal SHARE, and the other ends of the resistor R9 and the capacitor C6 are grounded.

2. A current balancing circuit composed of an operational amplifier as claimed in claim 1, characterized in that: The resistor R1 , the resistor R2 , the resistor R3 , the resistor R5 , the capacitor C1 , the capacitor C2 , and the capacitor C3 constitute an in-phase proportional operation circuit.

3. A current balancing circuit composed of an operational amplifier as claimed in claim 1, characterized in that: The 5V voltage source and the resistor R6 form a bias voltage circuit.

4. A current balancing circuit composed of an operational amplifier as claimed in claim 1, characterized in that: The resistor R7, the resistor R8, the resistor R10, the capacitor C5 and the operational amplifier U2 form a voltage error amplification circuit.

5. The current balancing circuit formed by an operational amplifier as claimed in claim 1, characterized in that: The resistor R9 and the capacitor C6 form a filter circuit.

6. A current balancing circuit formed by an operational amplifier as claimed in claim 1, characterized in that: The gate of the MOS transistor Q1 is connected to the control power supply VCC2 to form an output protection circuit.

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