Bipolar power supply power tube current sharing circuit

Abstract

The invention discloses a bipolar power tube current sharing circuit which comprises a plurality of power tube branch modules. The power tube branch module comprises an input end, a grounding end, an MOSFET device with a drain electrode connected with a power supply, a comparator, a first resistor connected in series between a source electrode of the MOSFET device and the grounding end, a fourth resistor connected in series between a grid electrode and a source electrode of the MOSFET device, a fifth resistor connected in series between the source electrode of the MOSFET device and an inverted input end of the comparator, and a third resistor connected in series between the source electrode of the MOSFET device and the inverted input end of the comparator. The eleventh resistor and the sixth resistor are connected in series between the input end and the inverting input end of the comparator, the eighth resistor is connected in series between the grid electrode of the MOSFET device and the output end of the comparator, and the ninth resistor is connected in series between the non-inverting input end and the grounding end of the comparator; the input ends of the power tube branch modules are connected in parallel, and the drain electrodes of the MOSFET devices of the power tube branch modules are connected in parallel. According to the invention, each MOSFET device is independently controlled in a negative feedback mode, and the purpose of accurate shunting can be achieved.

Description

Technical Field

[0001] The invention relates to a bipolar power supply tube current sharing circuit. Background Art

[0002] In today's electrified world, high-power scenarios are often used. A single power tube will be stretched at this time, so parallel connection of power tubes is particularly practical. In a MOSFET parallel circuit, if the resistance of each branch is equal, the current value of each branch is theoretically equal under the same voltage drop; but the wires in actual use have resistance, and even MOSFETs produced in the same batch will have some differences. At this time, the branch with the smallest resistance gets the largest current, and the MOSFET in this branch is prone to damage. A common solution is to start from the physical properties and use the positive temperature characteristics of MOSFET. When the current is too large and the temperature rises, the on-resistance increases at the same time to reduce the shared current, but in the case of rapidly changing output, this current balancing method is not very effective. Summary of the invention

[0003] In order to solve the defects of the prior art, the present invention provides a bipolar power supply power tube current sharing circuit, including a plurality of power tube branch modules; The power tube branch module includes: an input terminal, a ground terminal, a MOSFET device having a drain connected to a power supply, a comparator, a first resistor connected in series between the source of the MOSFET device and the ground terminal, a fourth resistor connected in series between the gate of the MOSFET device and the source, a fifth resistor connected in series between the source of the MOSFET device and the inverting input terminal of the comparator, an eleventh resistor and a sixth resistor connected in series between the input terminal and the inverting input terminal of the comparator, an eighth resistor connected in series between the gate of the MOSFET device and the output terminal of the comparator, and a ninth resistor connected in series between the in-phase input terminal of the comparator and the ground terminal; The input ends of the power tube branch modules are connected in parallel, the grounding ends of the power tube branch modules are grounded, and the drains of the MOSFET devices of the power tube branch modules are connected in parallel.

[0004] Preferably, the fifth resistor and the sixth resistor have the same resistance value.

[0005] Preferably, the resistance value of the first resistor of each power tube branch module is the same.

[0006] Preferably, the power tube branch module further includes: a first capacitor connected in series between the inverting input terminal and the output terminal of the comparator.

[0007] Preferably, the power tube branch module also includes: a first transistor having an emitter connected to the ground terminal, a second resistor connected in series between the source of the MOSFET device and the base of the first transistor, a third resistor connected in series between the base of the first transistor and the ground terminal, a second transistor having an emitter connected to the output terminal of the comparator, a base connected to the collector of the first transistor, and a collector connected to the inverting input terminal of the comparator, and a seventh resistor connected in series between the emitter and base of the second transistor.

[0008] Preferably, the MOSFET device is an N-channel MOSFET device.

[0009] Preferably, the first transistor is an NPN transistor.

[0010] Preferably, the second transistor is a PNP transistor.

[0011] The advantages and beneficial effects of the present invention are as follows: the present invention uses a negative feedback method to independently control each MOSFET device, thereby achieving the purpose of accurate current division.

[0012] The working principle of the bipolar power supply power tube current sharing circuit of the present invention is as follows: A set current is loaded to the input end of the power tube branch module; the first resistor is a current sampling resistor; the fifth resistor and the sixth resistor are voltage divider resistors of the comparator, and the resistance values ​​of the fifth resistor and the sixth resistor are the same; The comparator controls the conduction level of the MOSFET device: When the conduction degree of the MOSFET device is too large, the current flowing through the first resistor increases, the voltage input to the fifth resistor increases, the voltage at the inverting input terminal of the comparator increases, the voltage at the output terminal of the comparator decreases, and the conduction degree of the MOSFET device decreases; When the conduction degree of the MOSFET device is too small, the current flowing through the first resistor becomes smaller, the voltage input to the fifth resistor becomes smaller, the voltage at the inverting input terminal of the comparator becomes smaller, the voltage at the output terminal of the comparator becomes larger, and the conduction degree of the MOSFET device becomes larger; This ensures that the conduction level of the MOSFET device is only controlled by the set current loaded at the input end.

[0013] The resistance value of the first resistor (current sampling resistor) of each power tube branch module is the same; the current value flowing through the MOSFET device of each power tube branch module is the same.

[0014] The first transistor and the second transistor form a protection circuit to prevent excessive current from flowing through the first resistor (current sampling resistor); the second resistor and the third resistor are connected in series and in parallel with the first resistor. When the current of the MOSFET device is abnormally high, the voltage of the first resistor becomes high, and the voltage of the third resistor also becomes high. When the voltage of the third resistor exceeds the conduction voltage of the first transistor, the first transistor is turned on, driving the second transistor to be turned on, and the voltage at the output end of the comparator becomes smaller, reducing the conduction degree of the MOSFET device and reducing the current flowing through the MOSFET device.

[0015] The present invention also has the following characteristics: 1. Theoretically, there is no upper limit to the number of MOSFET devices connected in parallel in the present invention, and at least 12 groups can be connected in parallel.

[0016] 2. Each branch of the present invention is provided with current limiting protection.

[0017] 3. The present invention utilizes negative feedback to ensure that the current in each branch is consistent with a preset value.

[0018] 4. The present invention can realize both current output and current injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the circuit diagram of a single power tube branch module; Figure 2 It is a circuit diagram of embodiment 1 of the present invention. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0021] The present invention provides a bipolar power supply power tube current sharing circuit, comprising a plurality of power tube branch modules; like Figure 1As shown, the power tube branch module includes: an input end (IN), a ground end, a MOSFET device (M1) whose drain is connected to a power supply (VDD), a comparator (U2), a first transistor (Q1) whose emitter is connected to the ground end, a second transistor (Q2) whose emitter is connected to the output end of the comparator (U2), whose base is connected to the collector of the first transistor (Q1), and whose collector is connected to the inverting input end of the comparator (U2), a first resistor (R1) connected in series between the source of the MOSFET device (M1) and the ground end, a second resistor (R2) connected in series between the source of the MOSFET device (M1) and the base of the first transistor (Q1), a third resistor (R3) connected in series between the base of the first transistor (Q1) and the ground end, a fourth resistor (R4) connected in series between the gate and source of the MOSFET device (M1), and a a fifth resistor (R5) connected in series between the source and the inverting input terminal of the comparator (U2); an eleventh resistor (R11) and a sixth resistor (R6) connected in series between the input terminal (IN) and the inverting input terminal of the comparator (U2); a seventh resistor (R7) connected in series between the emitter and the base of the second transistor (Q2); an eighth resistor (R8) connected in series between the gate of the MOSFET device (M1) and the output terminal of the comparator (U2); a ninth resistor (R9) connected in series between the in-phase input terminal and the ground terminal of the comparator (U2); and a first capacitor (C1) connected in series between the inverting input terminal and the output terminal of the comparator (U2); the MOSFET device (M1) is an N-channel MOSFET device; the first transistor (Q1) is an NPN transistor; the second transistor (Q2) is a PNP transistor; the fifth resistor (R5) and the sixth resistor (R6) have the same resistance value; The input terminals (IN) of the power tube branch modules are connected in parallel, the ground terminals of the power tube branch modules are grounded, the drains of the MOSFET devices (M1) of the power tube branch modules are connected in parallel, and the resistance values ​​of the first resistors (R1) of the power tube branch modules are the same.

[0022] The working principle of the bipolar power supply power tube current sharing circuit of the present invention is as follows: A set current is loaded to an input end (IN) of the power tube branch module; the first resistor (R1) is a current sampling resistor; the fifth resistor (R5) and the sixth resistor (R6) are voltage dividing resistors of the comparator (U2), and the fifth resistor (R5) and the sixth resistor (R6) have the same resistance value; The comparator (U2) controls the conduction level of the MOSFET device (M1): When the conduction degree of the MOSFET device (M1) is too large, the current flowing through the first resistor (R1) increases, the voltage input to the fifth resistor (R5) increases, the voltage at the inverting input terminal of the comparator (U2) increases, the voltage at the output terminal of the comparator (U2) decreases, and the conduction degree of the MOSFET device (M1) decreases; When the conduction degree of the MOSFET device (M1) is too small, the current flowing through the first resistor (R1) decreases, the voltage input to the fifth resistor (R5) decreases, the voltage at the inverting input terminal of the comparator (U2) decreases, the voltage at the output terminal of the comparator (U2) increases, and the conduction degree of the MOSFET device (M1) increases; This ensures that the conduction level of the MOSFET device (M1) is only controlled by the set current loaded at the input terminal (IN).

[0023] The resistance value of the first resistor (R1) (current sampling resistor) of each power tube branch module is the same; the current value flowing through the MOSFET device (M1) of each power tube branch module is the same.

[0024] The first transistor (Q1) and the second transistor (Q2) form a protection circuit to prevent excessive current from flowing through the first resistor (R1) (current sampling resistor); the second resistor (R2) and the third resistor (R3) are connected in series and connected in parallel with the first resistor (R1); when the current of the MOSFET device (M1) is abnormally high, the voltage of the first resistor (R1) becomes higher, and the voltage of the third resistor (R3) also becomes higher; when the voltage of the third resistor (R3) exceeds the conduction voltage of the first transistor (Q1), the first transistor (Q1) is turned on, driving the second transistor (Q2) to be turned on, and the voltage at the output end of the comparator (U2) becomes smaller, thereby reducing the conduction degree of the MOSFET device (M1) and reducing the current flowing through the MOSFET device (M1).

[0025] The specific embodiments of the present invention are as follows: Example

[0026] The circuit diagram of Example 1 is as follows Figure 2 As shown, M1 and M2 are parallel MOSFETs, which can be expanded to multiple; R1 and R12 are current sampling resistors; U1 outputs the current setting value, R5 and R6 are the voltage divider resistors of the comparator U2, and R16 and R17 are the voltage divider resistors of the comparator U3, and the voltage divider resistors have the same value; U2 controls the conduction degree of M1: when the conduction degree of M1 is too large, the current flowing through R1 increases, the voltage input to R5 increases, the voltage at the negative feedback terminal of U2 increases, the output voltage of U2 decreases, and the conduction degree of M1 decreases; when the conduction degree of M1 is too small, the current flowing through R1 decreases, the voltage input to R5 decreases, the voltage at the negative feedback terminal of U2 decreases, the output voltage of U2 increases, and the conduction degree of M1 increases; Similarly, U3 controls the conduction degree of M2; The above ensures that the conduction degree of M1 and M2 is only controlled by the output of U1.

[0027] When the sampling resistors have the same value, that is, R1=R12, because UR1=UR12, IR1=IR12, the current values ​​flowing through M1 and M2 are the same.

[0028] Q1 and Q2 form a protection circuit to prevent excessive current from flowing through the sampling resistor R1; R2 and R3 are connected in series and in parallel with R1. When the current of M1 is abnormally high, UR1 becomes high, and UR3 also becomes high. When it exceeds UBE (ON) of Q1, Q1 is turned on, driving Q2 to turn on, and U2 output becomes smaller, reducing the conduction degree of M1 and reducing the current flowing through M1; the same is true for Q3 and Q4.

[0029] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bipolar power tube current sharing circuit, characterized in that: It includes a plurality of power tube branch modules; The power tube branch module includes: an input terminal, a ground terminal, a MOSFET device having a drain connected to a power supply, a comparator, a first resistor connected in series between the source of the MOSFET device and the ground terminal, a fourth resistor connected in series between the gate of the MOSFET device and the source, a fifth resistor connected in series between the source of the MOSFET device and the inverting input terminal of the comparator, an eleventh resistor and a sixth resistor connected in series between the input terminal and the inverting input terminal of the comparator, an eighth resistor connected in series between the gate of the MOSFET device and the output terminal of the comparator, and a ninth resistor connected in series between the in-phase input terminal of the comparator and the ground terminal; The input ends of the power tube branch modules are connected in parallel, the grounding ends of the power tube branch modules are grounded, and the drains of the MOSFET devices of the power tube branch modules are connected in parallel.

2. The bipolar power tube current sharing circuit according to claim 1, characterized in that: The fifth resistor and the sixth resistor have the same resistance value.

3. The bipolar power tube current sharing circuit according to claim 1, characterized in that: The resistance value of the first resistor of each power tube branch module is the same.

4. The bipolar power tube current sharing circuit according to claim 1, characterized in that: The power tube branch module further includes: a first capacitor connected in series between the inverting input terminal and the output terminal of the comparator.

5. The bipolar power tube current sharing circuit according to claim 1, characterized in that: The power tube branch module also includes: a first transistor connected to the emitter and the ground terminal, a second resistor connected in series between the source of the MOSFET device and the base of the first transistor, a third resistor connected in series between the base of the first transistor and the ground terminal, a second transistor connected to the emitter and the output terminal of the comparator, the base and the collector of the first transistor, and the collector and the inverting input terminal of the comparator, and a seventh resistor connected in series between the emitter and the base of the second transistor.

6. The bipolar power tube current sharing circuit according to claim 1, characterized in that: The MOSFET device is an N-channel MOSFET device.

7. The bipolar power tube current sharing circuit according to claim 5, characterized in that: The first transistor is an NPN transistor.

8. The bipolar power tube current sharing circuit according to claim 5, characterized in that: The second transistor is a PNP transistor.

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