Battery charging and discharging current sampling equipment and circuit thereof

Abstract

The utility model provides a battery charging and discharging current sampling device and a circuit thereof, when a battery is charged, charging current starts from a power supply unit, sequentially flows through the battery and a resistor RS, charges the battery and enables the voltage of the resistor RS to be forward voltage; when the battery is discharged, current starts from the battery, flows through the resistor RS from the positive electrode of the battery and then flows back to the negative electrode of the battery, so that the voltage of the resistor RS is reverse voltage; two operational amplifiers which are in forward connection or reverse connection between the grounding end and the non-grounding end of the resistor RS correspondingly amplify the input forward voltage or reverse voltage into forward voltage signals which can be received by the MCU, and the MCU receives the voltage signals and calculates the magnitude of charging and discharging current according to the voltage signals. Accurate detection of battery charging and discharging is realized; moreover, the circuit is simple in structure, the cost of required electronic components is low, the cost of charging and discharging detection is effectively reduced, and the cost performance is high.

Description

Technical Field

[0001] The utility model relates to the technical field of current sampling, in particular to a battery charging and discharging current sampling device and a circuit thereof. Background Art

[0002] In the prior art, most rechargeable devices use the method of analyzing voltage to estimate battery power due to cost and other reasons. However, different models of batteries have different voltages at the same capacity, and the same battery has different voltages at different life stages at the same capacity, resulting in poor measurement accuracy of the method of estimating battery power by analyzing voltage.

[0003] With the development of technology, most devices now contain MCU, and most MCUs have A / D (analog / digital) conversion modules that can complete sampling and calculation work, but direct use can only test the positive current in one direction of charging or discharging, and there is no way to directly sample the negative current. Although it is simple and direct to directly use the coulomb counter chip, the coulomb counter chip is expensive and not cost-effective.

[0004] Therefore, it is necessary to provide a low-cost, cost-effective and relatively accurate charge and discharge detection device. Utility Model Content

[0005] In view of the technical problems that the method of obtaining power by voltage analysis in battery charge and discharge detection in the prior art has poor accuracy and large usage restrictions, and the cost of using equipment such as coulomb meters is high, the utility model provides a battery charge and discharge current sampling device and its circuit with accurate detection, wide adaptability and low manufacturing cost.

[0006] A battery charging and discharging current sampling circuit, comprising a battery, a current sampling unit, a first voltage signal amplifying circuit, a second voltage signal amplifying circuit and an MCU for detecting the size of the battery charging and discharging current; the current sampling unit comprises a resistor RS; one end of the battery is connected to a working voltage, and the other end is connected to a resistor RS and then grounded; and the positive electrode of the battery is connected to the grounding end of the resistor RS; the first voltage signal amplifying circuit comprises a voltage signal amplifying unit and a protection circuit; the voltage signal amplifying unit comprises an operational amplifier, a resistor R1 and a resistor R3; the protection circuit comprises a resistor R2, the resistor R1 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier; the non-inverting input terminal of the operational amplifier The input end is connected to the ground end of the resistor RS through the resistor R2, the inverting input end of the operational amplifier is connected to the resistor R3, and is respectively connected to the negative electrode of the operational amplifier and the non-ground end of the resistor RS; the output end of the operational amplifier is electrically connected to an input end of the MCU; the composition structure of the second voltage signal amplifying circuit is consistent with that of the first voltage signal amplifying circuit, and the non-inverting input end of the operational amplifier of the second voltage signal amplifying circuit is connected to the non-ground end of the resistor RS through the resistor R2, and the inverting input end of the operational amplifier is connected to the resistor R3, and is respectively connected to the negative electrode of the operational amplifier and the ground end of the resistor RS; the output end of the operational amplifier is electrically connected to the other input end of the MCU.

[0007] Furthermore, a resistor R5 is included, one end of the resistor R5 is connected to the output end of the operational amplifier, and the other end of the resistor R5 is connected to the input end of the MCU.

[0008] Furthermore, a capacitor C1 is included, and the capacitor C1 is connected in parallel between the resistor R5 and the negative electrode of the operational amplifier.

[0009] Furthermore, the operational amplifiers of the first voltage signal amplifying circuit and the second voltage signal amplifying circuit are two groups of independently powered common-mode operational amplifiers.

[0010] Furthermore, the amplification factor of the operational amplifier of the first voltage signal amplifying circuit is set to N+1 times, and the amplification factor of the operational amplifier of the second voltage signal amplifying circuit is set to N times, and N is greater than or equal to 1.

[0011] Furthermore, it also includes a power supply unit, one end of which is connected to the positive electrode of the battery, and the other end of which is connected to the ground end of the resistor RS.

[0012] The utility model also provides a battery charging and discharging current sampling device, including a device body, wherein the device body is provided with a battery charging and discharging current sampling circuit as described in any one of the above. The beneficial effects of the utility model are as follows: the utility model provides a battery charging and discharging current sampling device and its circuit, when the battery is charged, the charging current starts from the power supply unit, flows through the battery and the resistor RS in sequence, charges the battery and makes the voltage of the resistor RS a forward voltage; when the battery is discharged, the current starts from the battery, flows from the positive electrode of the battery through the resistor RS in sequence and then flows back to the negative electrode of the battery, so that the voltage of the resistor RS is a reverse voltage; and then through two operational amplifiers connected forward or reversely between the ground terminal and the non-ground terminal of the resistor RS, the input forward voltage or reverse voltage is respectively amplified into a forward voltage signal that the MCU can receive, and the MCU receives and calculates the size of the charging and discharging current according to the voltage signal, so as to realize accurate detection of battery charging and discharging; and the circuit structure is simple, the cost of the required electronic components is low, the cost of charging and discharging detection is effectively reduced, and the cost performance is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of a circuit structure for battery charging and discharging current sampling adopted by the utility model;

[0014] Figure 2 The figure is a schematic diagram of the circuit structure of the first voltage signal amplifying circuit adopted by the utility model.

[0015] Figure ID

[0016] 1. Battery; 2. Current sampling unit; 3. First voltage signal amplifying circuit; 4. Second voltage signal amplifying circuit; 5. MCU; 6. Power supply unit. DETAILED DESCRIPTION

[0017] In order to more clearly understand the above-mentioned purpose, features and advantages of the utility model, the utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0018] refer to Figure 1 As shown, a battery charging and discharging current sampling circuit includes a battery 1, a current sampling unit 2, a first voltage signal amplifying circuit 3, a second voltage signal amplifying circuit 4 and an MCU 5 for detecting the charging and discharging current of the battery 1.

[0019] Specifically, the current sampling unit 2 includes a resistor RS; one end of the battery 1 is connected to the working voltage, and the other end is connected to a resistor RS and then grounded; and the positive electrode of the battery 1 is connected to the ground end of the resistor RS.

[0020] refer to Figure 1 and Figure 2 As shown, the first voltage signal amplifying circuit 3 includes a voltage signal amplifying unit and a protection circuit; the voltage signal amplifying unit includes an operational amplifier, a resistor R1 and a resistor R3, and the resistors R1 and R3 are used to cooperate with the operational amplifier to adjust the amplification factor of the operational amplifier.

[0021] The protection circuit includes a resistor R3, which is used to prevent the reverse voltage or reverse current from being too large and burning the operational amplifier or MCU chip. The resistor R1 is connected in parallel between the inverting input and output of the operational amplifier; the non-inverting input of the operational amplifier is connected to the grounding end of the resistor RS through the resistor R2, the inverting input of the operational amplifier is connected to the resistor R3, and is respectively connected to the negative electrode of the operational amplifier and the non-grounding end of the resistor RS; the output of the operational amplifier is electrically connected to an input end of the MCU. It can be seen that the operational amplifier of the first voltage signal amplification circuit 3 is reversely connected between the grounding end and the non-grounding end of the resistor RS.

[0022] The composition structure of the second voltage signal amplifying circuit 4 is consistent with that of the first voltage signal amplifying circuit 3, and the non-inverting input terminal of the operational amplifier of the second voltage signal amplifying circuit 4 is connected to the non-grounded terminal of the resistor RS through the resistor R2, and the inverting input terminal of the operational amplifier is connected to the resistor R3, and is respectively connected to the negative electrode of the operational amplifier and the grounded terminal of the resistor RS; the output terminal of the operational amplifier is electrically connected to the other input terminal of the MCU. It can be seen that the operational amplifier of the second voltage signal amplifying circuit 4 is connected in the forward direction between the grounded terminal and the non-grounded terminal of the resistor RS. In this embodiment, the operational amplifiers in the first voltage signal amplifying circuit 3 and the second voltage signal amplifying circuit 4 are two groups of independently powered in-phase operational amplifiers.

[0023] The charge and discharge current of the battery 1 forms positive and reverse voltages after flowing through the current sampling unit 2, and then the forward voltage is input into the voltage signal amplification unit of the second voltage signal amplification circuit 4 or the reverse voltage is input into the voltage signal amplification unit of the first voltage signal amplification circuit 3 to amplify the forward voltage signal or the reverse voltage signal into a forward voltage signal that can be received by the AD (analog-to-digital conversion) module of the MCU5. The MCU5 receives the forward voltage signal and calculates the charge and discharge current based on the forward voltage signal and the known resistance values ​​of each resistor and the amplification factor of the operational amplifier.

[0024] Specifically, when the battery is charged, the charging current starts from the power supply unit 6, flows through the battery 1 and the resistor RS in sequence to charge the battery; at this time, the ground end of the resistor RS is negative, and the non-ground end is positive, that is, the voltage of the resistor RS is a forward voltage, and then the voltage signal amplification unit of the second voltage signal amplification circuit 4 amplifies the forward voltage into a voltage signal that can be received by the AD (analog-to-digital conversion) module of the MCU5. The MCU5 receives the voltage signal and calculates the discharge current based on the voltage signal and the known resistance values ​​of each resistor and the amplification factor of the operational amplifier. When the battery is discharged, the discharge current starts from battery 1, flows from the positive electrode of battery 1 through resistor RS in sequence, and then flows back to the negative electrode of battery 1. At this time, the ground end of resistor RS is positive and the non-ground end is negative, that is, the voltage of resistor RS is a reverse voltage. Then the reverse voltage is amplified by the voltage signal amplification unit of the first voltage signal amplification circuit 3 and converted into a forward voltage signal that can be received by the AD (analog-to-digital conversion) module of the MCU5. MCU5 receives the forward voltage signal and calculates the charging current based on the voltage signal and the known resistance values ​​of each resistor and the amplification factor of the operational amplifier.

[0025] Since the resistor RS consumes part of the output voltage of the first voltage signal amplifier circuit 3 when the battery is discharged, the voltage signals output by the two groups of operational amplifiers are inconsistent when the charging current is the same as the discharging current. Therefore, in this embodiment, the amplification factor of the operational amplifier of the first voltage signal amplifier circuit 3 is set to N+1 times, and the amplification factor of the operational amplifier of the second voltage signal amplifier circuit 4 is set to N times, and N is greater than or equal to 1, so that when the charging current is the same as the discharging current, the forward voltage signals output by the operational amplifier of the first voltage signal amplifier circuit 3 and the operational amplifier of the second voltage signal amplifier circuit 4 are consistent; it is convenient for users to obtain the charging and discharging current values, keep the charging and discharging currents the same, help prevent overcharging or over-discharging of the battery, and improve battery safety.

[0026] After the MCU reads the forward voltage or the reverse voltage and amplifies the forward voltage signal, it calculates the correct charge and discharge current value according to the set N value combined with the known resistance values ​​of each resistor. For example, the amplification factor of the operational amplifier of the first voltage signal amplifying circuit 3 is set to 11 times, and the amplification factor of the operational amplifier of the first voltage signal amplifying circuit 4 is set to 10 times. When the MCU reads the forward voltage or the reverse voltage and calculates the charge and discharge current value, the multiples used by the operational amplifier for calculation are both 10 times.

[0027] The current acquisition unit 2 further includes a resistor R4, which is connected in parallel with the battery 1 and the resistor RS. The resistor R4 can limit the current passing through the resistor RS to prevent it from being damaged by excessive current, and can also reduce noise and interference in the circuit to protect the circuit from being used safely.

[0028] The battery charging and discharging current sampling circuit also includes a resistor R5 and a capacitor C1, wherein one end of the resistor R5 is connected to the output end of the operational amplifier, and the other end is connected to the input end of the MCU5; the capacitor C1 is connected in parallel between the resistor R5 and the negative electrode of the operational amplifier. The capacitor C1 is connected in parallel between the resistor R5 and the negative electrode of the operational amplifier to form a simple RC low-pass filter, which can reduce or eliminate high-frequency noise at the output end of the voltage signal amplification circuit.

[0029] The battery charging and discharging current sampling circuit further includes a power supply unit 6, one end of the power supply unit 6 is connected to the positive electrode of the battery, and the other end is connected to the ground end of the resistor RS. The power supply unit 6 is used to charge the battery 1.

[0030] The utility model also provides a battery charging and discharging current sampling device, comprising a device body, wherein the battery charging and discharging current sampling circuit as described in any one of the above items is arranged in the device body.

[0031] The utility model provides a battery charging and discharging current sampling device and a circuit thereof, which realizes battery charging and discharging detection while having a simple circuit structure and low-cost electronic components, and can complete the detection of charging and discharging current at a relatively low cost.

[0032] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A battery charging and discharging current sampling circuit, characterized in that: It includes a battery, a current sampling unit, a first voltage signal amplifying circuit, a second voltage signal amplifying circuit and an MCU for detecting the charging and discharging current of the battery; The current sampling unit includes a resistor RS; one end of the battery is connected to the working voltage, and the other end is connected to a resistor RS and then grounded; and the positive electrode of the battery is connected to the ground end of the resistor RS; The first voltage signal amplifying circuit includes a voltage signal amplifying unit and a protection circuit; the voltage signal amplifying unit includes an operational amplifier, a resistor R1 and a resistor R3; the protection circuit includes a resistor R2, and the resistor R1 is connected in parallel between the inverting input terminal and the output terminal of the operational amplifier; the non-inverting input terminal of the operational amplifier is connected to the ground terminal of the resistor RS through the resistor R2, the inverting input terminal of the operational amplifier is connected to the resistor R3, and is respectively connected to the negative electrode of the operational amplifier and the non-ground terminal of the resistor RS; the output terminal of the operational amplifier is electrically connected to an input terminal of the MCU; The composition structure of the second voltage signal amplifying circuit is consistent with that of the first voltage signal amplifying circuit, and the non-inverting input terminal of the operational amplifier of the second voltage signal amplifying circuit is connected to the non-grounded end of the resistor RS through the resistor R2, and the inverting input terminal of the operational amplifier is connected to the resistor R3, and is respectively connected to the negative electrode of the operational amplifier and the grounded end of the resistor RS; the output terminal of the operational amplifier is electrically connected to the other input terminal of the MCU.

2. A battery charging and discharging current sampling circuit according to claim 1, characterized in that: It also includes a resistor R5, one end of which is connected to the output end of the operational amplifier, and the other end of which is connected to the input end of the MCU.

3. A battery charging and discharging current sampling circuit according to claim 2, characterized in that: The device further comprises a capacitor C1 , which is connected in parallel between the resistor R5 and the negative electrode of the operational amplifier.

4. A battery charging and discharging current sampling circuit according to claim 1, characterized in that: The operational amplifiers of the first voltage signal amplifying circuit and the second voltage signal amplifying circuit are two groups of independently powered common-mode operational amplifiers.

5. A battery charging and discharging current sampling circuit according to claim 1, characterized in that: The amplification factor of the operational amplifier of the first voltage signal amplifying circuit is set to N+1 times, and the amplification factor of the operational amplifier of the second voltage signal amplifying circuit is set to N times, and N is greater than or equal to 1.

6. A battery charging and discharging current sampling circuit according to claim 1, characterized in that: It also includes a power supply unit, one end of which is connected to the positive electrode of the battery, and the other end of which is connected to the ground end of the resistor RS.

7. A battery charging and discharging current sampling device, characterized in that: The device comprises a device body, wherein a battery charging and discharging current sampling circuit as claimed in any one of claims 1 to 6 is arranged in the device body.

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