CN-224233656-U - Power supply current detection circuit and battery management system

CN224233656UCN 224233656 UCN224233656 UCN 224233656UCN-224233656-U

Abstract

The utility model provides a power supply current detection circuit which comprises a sampling and operational amplification module, a sampling and operational processing module and an operational amplification voltage stabilizing power supply module, wherein the sampling and operational amplification module is connected between a power supply output end and a grounding end, a sampling point is arranged on an output line of the sampling and operational amplification module, the sampling and operational amplification module is connected with the sampling point, the sampling and operational processing module is used for collecting voltage of the sampling point and calculating a current value output by the power supply output end according to the voltage of the sampling point, the operational amplification voltage stabilizing power supply module comprises a voltage stabilizing unit, one end of the voltage stabilizing unit is connected with the power supply output end, the other end of the voltage stabilizing unit is connected with one end of a voltage dividing unit in parallel, the other end of the voltage dividing unit is connected with a control end of the voltage dividing unit, and when the voltage of the power supply output end is increased, the voltage of the sampling and operational amplification module is increased, the voltage of the voltage stabilizing unit is increased, and the voltage of the negative power supply end of the sampling and operational amplification module is increased.

Inventors

WANG LEI
LIU XIAOHUI
HU ZHENGCONG
SHAO MINGKUAN

Assignees

上海海拉电子有限公司

Dates

Publication Date: 20260512
Application Date: 20250508

Claims (9)

1. The power supply current detection circuit is characterized by comprising a sampling and operational amplification module and a sampling and operational processing module; the sampling and operational amplification module is connected between the power supply output end and the grounding end, and a sampling point is arranged on an output line of the sampling and operational amplification module; the sampling and operation processing module is used for collecting the voltage of the sampling point and calculating the current value output by the power supply output end according to the voltage of the sampling point; the power supply device is characterized by further comprising an operational amplifier voltage-stabilizing power supply module; the operational amplifier voltage-stabilizing power supply module comprises a voltage-stabilizing unit and a voltage-dividing unit; The sampling and operational amplification module is used for sampling the power supply output end of the voltage stabilizing unit, and supplying the power supply output end of the voltage stabilizing unit to the sampling and operational amplification module; The other end of the voltage division unit is grounded, the enabling output end of the power supply current detection circuit is connected with the control end of the voltage division unit, the voltage division unit is used for jointly dividing voltage with the voltage stabilizing unit after the enabling output end outputs a current sampling enabling signal, and And the sampling and operational amplification module is used for increasing the self-voltage division when the voltage of the power supply output end is increased, so that the voltage of the negative power supply end of the sampling and operational amplification module is increased.
2. The power supply current detection circuit of claim 1, wherein, The voltage stabilizing unit comprises a first resistor and a voltage stabilizing diode; The first end of the first resistor is connected with the power supply output end, and the second end of the first resistor is connected with one end of the voltage dividing unit; The negative electrode and the positive electrode of the voltage stabilizing diode are respectively connected with the first end and the second end of the first resistor, and the voltage stabilizing diode is used for stabilizing the voltages at two ends of the first resistor; The positive power input end and the negative power input end of the sampling and operational amplification module are respectively connected with the first end and the second end of the first resistor.
3. The power supply current detection circuit of claim 2, wherein, The voltage dividing unit comprises a first triode and a second resistor; The collector of the first triode is connected with the second end of the first resistor, the emitter of the first triode is connected with one end of the second resistor, and the base of the first triode is connected with the enabling output end; The first triode is conducted after the enabling output end inputs a current sampling enabling signal, so that the first triode, the second resistor and the first resistor divide the voltage output by the power supply output end; And when the voltage input by the power input end is increased, the voltage division of the first triode and the second resistor is increased, so that the voltage of the negative power end of the sampling and operational amplification module is increased.
4. The power supply current detection circuit of claim 3, wherein, The operational amplifier voltage-stabilizing power supply module further comprises a third resistor and a fourth resistor; the third resistor is connected in series between the enabling output end and the base electrode of the first triode; One end of the fourth resistor is connected with the base electrode of the first triode, and the other end of the fourth resistor is connected with the other end of the second resistor and grounded.
5. The power supply current detection circuit of claim 4, wherein, The sampling and operational amplification module comprises an operational amplifier and a sampling resistor; One end of the sampling resistor is connected with the power supply output end; The positive input end of the operational amplifier is coupled with the other end of the sampling resistor, and the negative input end of the operational amplifier is coupled with one end of the sampling resistor; The positive power end and the negative power end of the operational amplifier are respectively connected with the first end and the second end of the first resistor; The sampling and operation processing module is connected with the sampling point and is used for collecting the voltage of the sampling point and calculating the current value of the current flowing through the sampling resistor according to the voltage of the sampling point.
6. The power supply current detection circuit of claim 5, wherein, The power supply current detection circuit further comprises a fifth resistor, a sixth resistor and a seventh resistor; The fifth resistor is connected between the other end of the sampling resistor and the positive input end of the operational amplifier; One end of the sixth resistor is connected with one end of the sampling resistor, and the other end of the sixth resistor is connected with the negative input end of the operational amplifier; One end of the seventh resistor is connected to the output end of the operational amplifier, and the other end of the seventh resistor is coupled to the sampling point.
7. The power supply current detection circuit of claim 6, wherein, The sampling and operational amplification module further comprises a second triode and an eighth resistor; The emitter of the second triode is connected with the other end of the sixth resistor and the negative output end of the operational amplifier to form the same node, the base of the second triode is connected with the other end of the seventh resistor, and the collector of the second triode is connected with one end of the eighth resistor; The other end of the eighth resistor is connected with the grounding end, and the sampling point is arranged between the eighth resistor and the collector electrode of the second triode.
8. The power supply current detection circuit of claim 7, wherein, The sampling and operation processing module is used for collecting the sampling point voltage and calculating a current value Io of the current flowing through the sampling resistor according to the sampling point voltage U o by using the formula (1); io= (Uo x R6)/(R0 x R8) formula (1); Wherein, R6, R0 and R8 are the resistance values of the sixth resistor, the sampling resistor and the eighth resistor respectively.
9. A battery management system comprising a power supply current detection circuit as claimed in any one of claims 1 to 8.

Description

Power supply current detection circuit and battery management system Technical Field The present utility model relates to the field of power supply current detection, and in particular, to a power supply current detection circuit and a battery management system. Background The current detection scheme in the market mostly adopts a small-resistance differential operational amplifier to directly collect the voltage of the output end of the operational amplifier and calculate the current flowing through the small-resistance. In this way, if the small resistor is placed at the power supply end, the rail-to-rail operational amplifier with larger common-mode voltage resistance is needed, and the output voltage of the operational amplifier can only be close to the power supply rail at maximum, so that the operational amplifier meeting the requirement is more expensive. Because the current of the low-voltage battery management system is about 100 milliamperes, and the voltage drop is too large due to the fact that the sampling resistor is too large, only milliohm-level resistors can be used, and therefore the variation range of the output voltage of the operational amplifier is small, and the post-stage ADC module cannot accurately measure the current of the system. Therefore, providing a power supply current detection circuit that improves the supply voltage of the negative supply rail of the op-amp, uses a low-cost solution of the low-common-mode voltage op-amp, reduces the cost, and does not affect the sampling accuracy, is a technical problem that needs to be solved by those skilled in the art. Disclosure of utility model In order to overcome the above-mentioned drawbacks, an object of the present utility model is to provide a power supply current detection circuit and a battery management system. The utility model can lead the negative power rail voltage to be increased when the power voltage is increased by setting up the voltage stabilizing power supply module as the positive and negative power supply circuits of the sampling and operational amplification module, and can also provide stable power supply voltage at the same time, thereby reducing the requirement of the circuit on common-mode voltage resistance of the power input end, and being capable of selecting the integrated operational amplifier with lower common-mode voltage in application, thereby reducing the cost. The power supply does not need to be independently arranged, so that the hardware cost is further saved. The utility model discloses a power supply current detection circuit, which comprises a sampling and operational amplification module and a sampling and operational processing module; the sampling and operational amplification module is connected between the power supply output end and the grounding end, and a sampling point is arranged on an output line of the sampling and operational amplification module; the sampling and operation processing module is used for collecting the voltage of the sampling point and calculating the current value output by the power supply output end according to the voltage of the sampling point; The system also comprises an operational amplifier voltage-stabilizing power supply module; the operational amplifier voltage-stabilizing power supply module comprises a voltage-stabilizing unit and a voltage-dividing unit; One end of the voltage stabilizing unit is connected with the power output end, and the other end of the voltage stabilizing unit is connected with one end of the voltage dividing unit; The positive and negative power supply ends of the sampling and operational amplification module are connected to the two ends of the voltage stabilizing unit, and the voltage stabilizing unit is used for providing stable working voltage for the sampling and operational amplification module; The other end of the voltage division unit is grounded, the enabling output end of the power supply current detection circuit is connected with the control end of the voltage division unit, the voltage division unit is used for jointly dividing voltage with the voltage stabilizing unit after the enabling output end outputs a current sampling enabling signal, and And the sampling and operational amplification module is used for increasing the self-voltage division when the voltage of the power supply output end is increased, so that the voltage of the negative power supply end of the sampling and operational amplification module is increased. Optionally, the voltage stabilizing unit comprises a first resistor and a voltage stabilizing diode; The first end of the first resistor is connected with the power supply output end, and the second end of the first resistor is connected with one end of the voltage dividing circuit; The cathode and the anode of the zener diode are respectively connected with the first end and the first end of the first resistor The voltage stabilizing diode is used for stabilizing the voltages at two ends o