Low-cost current sampling circuit capable of realizing automatic range switching

Abstract

The utility model relates to the technical field of energy storage systems, in particular to a low-cost current sampling circuit capable of realizing automatic range switching. A low-cost current sampling circuit capable of realizing automatic range switching comprises an aluminum substrate, an MCU, a driving chip, an operational amplifier, a resistor and an MOS tube, the aluminum substrate is a base material of the current sampling circuit, and the aluminum substrate is provided with a B-port and a P-port. Compared with the prior art, the current sampling circuit capable of realizing automatic range switching is low in cost, an aluminum substrate is selected as a base material of a BMS high-power circuit, alloy resistors of different numbers are connected in parallel to serve as current sensors of different ranges, and MOS transistors of different numbers are connected in parallel to serve as change-over switches of different ranges. The problem that an existing BMS is poor in wide-range precision is solved, cost is low, and reliability is high.

Description

Technical Field

[0001] This utility model relates to the field of energy storage system technology, specifically a low-cost current sampling circuit for automatically switching measurement ranges. Background Technology

[0002] Battery Management System (BMS) is mainly used in electric vehicles, energy storage systems and other fields. It is responsible for monitoring the battery status, such as voltage, current and temperature, and controlling the charging and discharging of the battery to ensure the safe and efficient operation of the battery and extend its life.

[0003] Currently, BMS uses shunts or Hall effect sensors to detect current. Shunts are inexpensive but generate significant heat. Measuring 300A current requires a 500A rated shunt, but a 500A shunt is difficult to measure minute currents of around 50mA. In actual battery use, there are scenarios where the battery operates with minute currents. Due to the accuracy issue, the battery capacity SOC calculation is inaccurate, affecting the user experience. Hall effect sensors are expensive, have poor accuracy, and cannot solve the above problems.

[0004] Some have suggested using a shunt and a Hall sensor together. However, if you want to accurately measure tiny currents, the shunt will overheat significantly, making it impractical for engineering projects. Dual-range Hall sensors would further increase costs and offer limited improvement in accuracy. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this utility model provides a low-cost current sampling circuit that can automatically switch ranges, solving the measurement accuracy problem of existing BMS in a wide current range, and at a low cost.

[0006] To achieve the above objectives, a low-cost current sampling circuit for automatic range switching is designed, comprising an aluminum substrate, an MCU, a driver chip, an operational amplifier, resistors, and MOSFETs. The aluminum substrate serves as the base material for the current sampling circuit and has B-ports and P-ports. The circuit is characterized in that: the two input terminals of the MCU are respectively connected to the output terminals of a first operational amplifier and a second operational amplifier; the two output terminals of the MCU are respectively connected to a first driver chip and a second driver chip; the OUTB terminal of the first driver chip is connected to one end of a first resistor, a second resistor, and a third resistor; the other ends of the first, second, and third resistors are respectively connected to the gate (G) terminals of the first, second, and third MOSFETs; the drain (D) terminals of the first, second, and third MOSFETs are combined with the source (S) terminals of a fourth, fifth, and sixth MOSFET; and the gate (G) terminals of the fourth, fifth, and sixth MOSFETs are respectively connected to the fourth resistor, the fifth resistor, the fifth resistor, and the sixth resistor. One end of the first and sixth resistors, and the other ends of the fourth, fifth, and sixth resistors are connected to the OUTA terminal of the first driver chip; the source terminals of the first, second, and third MOSFETs are connected to one end of the seventh, eighth, and ninth resistors, and the seventh resistor is connected in parallel with the first operational amplifier; the OUTB terminal of the second driver chip is connected to one end of the tenth resistor, the other end of the tenth resistor is connected to the gate terminal of the seventh MOSFET, the drain terminal of the seventh MOSFET is connected to the source terminal of the eighth MOSFET, the gate terminal of the eighth MOSFET is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is connected to the OUTA terminal of the second driver chip; the drain terminals of the fourth, fifth, sixth, and eighth MOSFETs are connected to the P-port of the aluminum substrate, and the twelfth resistor is connected in parallel with the second operational amplifier; the source terminal of the seventh MOSFET is connected to one end of the twelfth resistor; the other ends of the seventh, eighth, ninth, and twelfth resistors are connected to the B-port of the aluminum substrate.

[0007] The MCU is connected to the INA and INB terminals of the first and second driver chips via an IO port or a timer interface that can output PWM signals.

[0008] The MCU is connected to the outputs of the first operational amplifier and the second operational amplifier via an I / O port that supports external interrupts.

[0009] The MCU mentioned is an IC-type ARM core or C2000 core microcontroller.

[0010] The first, second, third, fourth, fifth, sixth, seventh, and eighth MOSFETs are N-channel or P-channel field-effect MOSFET power devices.

[0011] The first operational amplifier and the second operational amplifier are IC-type general-purpose operational amplifiers.

[0012] The first and second driver chips are IC-type MOS transistor gate driver chips.

[0013] The first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth resistors are alloy resistors.

[0014] Compared with the prior art, this utility model provides a low-cost current sampling circuit for automatic range switching. It selects an aluminum substrate as the base material for the high-power circuit of the BMS, uses different numbers of alloy resistors in parallel as current sensors with different ranges, and uses different numbers of MOSFETs in parallel as switching switches with different ranges. This solves the problem of poor accuracy of existing BMS with wide ranges, and is low in cost and highly reliable. Attached Figure Description

[0015] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] like Figure 1As shown, a low-cost current sampling circuit for automatic range switching includes an aluminum substrate, an MCU, a driver chip, an operational amplifier, resistors, and a MOSFET. The aluminum substrate serves as the base material for the current sampling circuit and has a B-port and a P-port. The two input terminals of the MCU are connected to the output terminals of the first operational amplifier D1 and the second operational amplifier D2, respectively. The two output terminals of the MCU are connected to the first driver chip U1 and the second driver chip U2, respectively. The OUTB terminal of the first driver chip U1 is connected to the first resistor R1, the second resistor R2, and the third resistor, respectively. One end of resistor R3, and the other ends of resistors R1, R2, and R3 are connected to the gates (G) of MOSFETs Q1, Q2, and Q3, respectively. The drains (D) of MOSFETs Q1, Q2, and Q3 are connected together with the sources (S) of MOSFETs Q4, Q5, and Q6. The gates (G) of MOSFETs Q4, Q5, and Q6 are connected to one end of resistors R4, R5, and R6, respectively. The other ends of resistors R5 and R6 are connected together to the OUTA terminal of the first driver chip U1; the source terminals of the first MOSFET Q1, the second MOSFET Q2, and the third MOSFET Q3 are connected together with one end of resistors R7, R8, and R9, and resistor R7 is connected in parallel with the first operational amplifier D1; the OUTB terminal of the second driver chip U2 is connected to one end of resistor R10, the other end of resistor R10 is connected to the gate terminal of the seventh MOSFET Q7, the drain terminal of the seventh MOSFET Q7 is connected to the source terminal of the eighth MOSFET Q8, and the eighth MOSFET... The gate (G) of the S-transistor Q8 is connected to one end of the eleventh resistor R11, and the other end of the eleventh resistor R11 is connected to the OUTA terminal of the second driver chip U2; the drains (D) of the fourth MOSFET Q4, the fifth MOSFET Q5, the sixth MOSFET Q6, and the eighth MOSFET Q8 are connected together to the P-port of the aluminum substrate; the twelfth resistor R12 is connected in parallel with the second operational amplifier D2; the source (S) of the seventh MOSFET Q7 is connected to one end of the twelfth resistor R12; the other ends of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the twelfth resistor R12 are connected together to the B-port of the aluminum substrate.

[0018] The MCU is connected to the INA and INB terminals of the first driver chip U1 and the second driver chip U2 via the IO port or the timer interface that can output PWM signals.

[0019] The MCU is connected to the outputs of the first operational amplifier D1 and the second operational amplifier D2 through an I / O port that supports external interrupts.

[0020] The MCU is an IC-type microcontroller with an ARM core or a C2000 core.

[0021] The first MOSFET Q1, the second MOSFET Q2, the third MOSFET Q3, the fourth MOSFET Q4, the fifth MOSFET Q5, the sixth MOSFET Q6, the seventh MOSFET Q7, and the eighth MOSFET Q8 are N-channel or P-channel field-effect MOSFET power devices.

[0022] The first operational amplifier D1 and the second operational amplifier D2 are IC-type general-purpose operational amplifiers.

[0023] The first driver chip U1 and the second driver chip U2 are IC-type MOS transistor gate driver chips.

[0024] The first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12 are alloy resistors.

[0025] Between the B- and P- terminals of the aluminum substrate of this invention, there are 8 MOSFETs and 12 alloy resistors. The MOSFETs and alloy resistors are connected in series between the B- and P- terminals. Six parallel MOSFETs and nine parallel alloy resistors form a high-current loop (the number of MOSFETs and alloy resistors is not limited; a larger number indicates a high-current loop, and a smaller number indicates a low-current loop). When a high current flows, it passes through the B- terminal, the six parallel MOSFETs, the nine parallel alloy resistors, and the P- terminal. One MOSFET and three alloy resistors are connected in series to form a low-current loop. When a low current flows, it passes through the B- terminal, the one MOSFET, the three alloy resistors, and the P- terminal. The six parallel MOSFETs in the high-current loop share one driving circuit (i.e., the first driving chip U1), while the one MOSFET in the low-current loop has its own driving circuit. The input signals of the driving circuits for the high-current loop and the low-current loop come from the processor MCU. The operational amplifiers for the high-current loop and the low-current loop generate interrupt signals that are input to the processor MCU.

[0026] When a large current flows, the operational amplifier detecting the small current (i.e., the second operational amplifier U2) has no output, while the operational amplifier detecting the large current (i.e., the first operational amplifier U1) has an output. The processor MCU controls the MOSFET in the large current loop to turn on and the MOSFET in the small current loop to turn off. When the current decreases, the operational amplifier detecting the small current (i.e., the second operational amplifier U2) has an output, while the operational amplifier detecting the large current (i.e., the first operational amplifier U1) has no output. The processor MCU controls the MOSFET in the small current loop to turn on and the MOSFET in the large current loop to turn off. When the current increases, the operational amplifier detecting the small current (i.e., the second operational amplifier U2) has no output, while the operational amplifier detecting the large current (i.e., the first operational amplifier U1) has an output. The processor MCU controls the MOSFET in the large current loop to turn on and the MOSFET in the small current loop to turn off.

[0027] This invention selects an aluminum substrate as the base material for the high-power circuit of the BMS, uses a high-precision alloy resistor as a sensor for detecting current, and uses a MOSFET as the protection actuator of the BMS. At the same time, the MOSFET also serves as a switch for switching the current detection circuit.

Claims

1. A low-cost current sampling circuit for automatic range switching, comprising an aluminum substrate, an MCU, a driver chip, an operational amplifier, resistors, and a MOSFET, wherein the aluminum substrate is the base material of the current sampling circuit, and the aluminum substrate is provided with a B-port and a P-port, characterized in that: The two input terminals of the MCU are connected to the output terminals of the first operational amplifier (D1) and the second operational amplifier (D2), respectively. The two output terminals of the MCU are connected to the first driver chip (U1) and the second driver chip (U2), respectively. The OUTB terminal of the first driver chip (U1) is connected to one end of the first resistor (R1), the second resistor (R2), and the third resistor (R3), respectively. The other ends of the first resistor (R1), the second resistor (R2), and the third resistor (R3) are connected to the gate (G) terminals of the first MOSFET (Q1), the second MOSFET (Q2), and the third MOSFET (Q3), respectively. The drains (D) of the first MOSFET (Q1), the second MOSFET (Q2), and the third MOSFET (Q3) are connected together with the sources (S) of the fourth MOSFET (Q4), the fifth MOSFET (Q5), and the sixth MOSFET (Q6). The gates (G) of the fourth MOSFET (Q4), the fifth MOSFET (Q5), and the sixth MOSFET (Q6) are connected to one end of the fourth resistor (R4), the fifth resistor (R5), and the sixth resistor (R6), respectively. The other ends of the fourth resistor (R4), the fifth resistor (R5), and the sixth resistor (R6) are connected together to the OUTA terminal of the first driver chip (U1). The first MOSFET (Q1)... 1) The source (S) terminals of the second MOSFET (Q2) and the third MOSFET (Q3) are connected together with one end of the seventh resistor (R7), the eighth resistor (R8), and the ninth resistor (R9). The seventh resistor (R7) is connected in parallel with the first operational amplifier (D1). The OUTB terminal of the second driver chip (U2) is connected to one end of the tenth resistor (R10), and the other end of the tenth resistor (R10) is connected to the gate (G) terminal of the seventh MOSFET (Q7). The drain (D) terminal of the seventh MOSFET (Q7) is connected to the source (S) terminal of the eighth MOSFET (Q8), and the gate (G) terminal of the eighth MOSFET (Q8) is connected to one end of the eleventh resistor (R11). The other end of the eleventh resistor (R11) is connected to the OUTA terminal of the second driver chip (U2); the drain terminals of the fourth MOSFET (Q4), fifth MOSFET (Q5), sixth MOSFET (Q6), and eighth MOSFET (Q8) are connected together to the P-port of the aluminum substrate; the source terminal of the seventh MOSFET (Q7) is connected to one end of the twelfth resistor (R12), and the twelfth resistor (R12) is connected in parallel with the second operational amplifier (D2); the other ends of the seventh resistor (R7), eighth resistor (R8), ninth resistor (R9), and twelfth resistor (R12) are connected together to the B-port of the aluminum substrate.

2. The low-cost current sampling circuit for automatic range switching according to claim 1, characterized in that: The MCU is connected to the INA and INB terminals of the first driver chip (U1) and the second driver chip (U2) via an IO port or a timer interface that can output PWM signals.

3. The low-cost current sampling circuit for automatic range switching according to claim 1, characterized in that: The MCU is connected to the outputs of the first operational amplifier (D1) and the second operational amplifier (D2) via an I / O port that supports external interrupts.

4. The low-cost current sampling circuit for automatic range switching according to claim 1 or 2 or 3, characterized in that: The MCU mentioned is an IC-type ARM core or C2000 core microcontroller.

5. The low-cost current sampling circuit for automatic range switching according to claim 1, characterized in that: The first MOSFET (Q1), second MOSFET (Q2), third MOSFET (Q3), fourth MOSFET (Q4), fifth MOSFET (Q5), sixth MOSFET (Q6), seventh MOSFET (Q7), and eighth MOSFET (Q8) are N-channel or P-channel field-effect MOSFET power devices.

6. The low-cost current sampling circuit for automatic range switching according to claim 1, characterized in that: The first operational amplifier (D1) and the second operational amplifier (D2) are IC-type general-purpose operational amplifiers.

7. The low-cost current sampling circuit for automatic range switching according to claim 1, characterized in that: The first driver chip (U1) and the second driver chip (U2) are IC-type MOS transistor gate driver chips.

8. A low-cost current sampling circuit for automatically switching ranges according to claim 1, characterized in that: The first resistor (R1), second resistor (R2), third resistor (R3), fourth resistor (R4), fifth resistor (R5), sixth resistor (R6), seventh resistor (R7), eighth resistor (R8), ninth resistor (R9), tenth resistor (R10), eleventh resistor (R11), and twelfth resistor (R12) are alloy resistors.

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