Temperature acquisition circuit and method, battery management system and electric vehicle

Abstract

The present disclosure relates to a temperature acquisition circuit and method, a battery management system, and an electric vehicle. The temperature acquisition circuit includes a first switch K1, a voltage-dividing resistor, a temperature sensor, and a second switch K2 connected in series in sequence, and further includes an analog-to-digital converter ADC. One end of the analog-to-digital converter ADC is connected between the voltage-dividing resistor and the temperature sensor, and the other end is connected between the temperature sensor and the second switch K2. Both the first switch K1 and the second switch K2 are single-pole double-throw switches, and the moving terminals of the first switch K1 and the second switch K2 can both be switched between the power supply Vcc and the ground terminal GND. The temperature acquisition circuit of the present disclosure does not need to use a high-precision power supply, and can ignore the influence of the reference source of the analog-to-digital converter, the accuracy of the temperature sensor, and the voltage-dividing resistor, so as to obtain accurate measurement data.

Description

Technical Field

[0001] The present disclosure relates to the field of electric vehicles, and more particularly, to a temperature acquisition circuit and method, a battery management system, and an electric vehicle. Background Art

[0002] In electric vehicles and large-scale energy storage systems, the temperature of the battery is data that must be measured to ensure the safety of the system. The acquisition accuracy of the temperature is crucial for the safety of electric vehicles and energy storage systems. Therefore, the temperature sensor (NTC) must have high accuracy and be able to truly reflect the temperature of the battery in real time. To measure the temperature data of the temperature sensor, an analog-to-digital converter (ADC) must be used. In addition to the accuracy of the temperature sensor and the resistor itself, the accuracy of the reference source (Vref) of the analog-to-digital converter also affects the temperature measurement accuracy of the temperature sensor. The acquisition method relying on a precise reference source cannot obtain accurate acquisition data. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a temperature acquisition circuit and method, a battery management system, and an electric vehicle, which solve the problem that the accuracy of the reference source of the analog-to-digital converter affects the temperature measurement accuracy of the temperature sensor, and at the same time reduce costs.

[0004] To achieve the above object, in a first aspect of the present disclosure, a temperature acquisition circuit is provided, which includes a first switch K1, a voltage-dividing resistor, a temperature sensor, and a second switch K2 connected in series in sequence, and also includes an analog-to-digital converter ADC. One end of the analog-to-digital converter ADC is connected between the voltage-dividing resistor and the temperature sensor, and the other end is connected between the temperature sensor and the second switch K2; both the first switch K1 and the second switch K2 are single-pole double-throw switches, and the moving terminals of the first switch K1 and the second switch K2 can both be switched between the power supply Vcc and the ground terminal GND.

[0005] Optionally, the moving terminals of the first switch K1 and the second switch K2 are not simultaneously connected to the power supply Vcc.

[0006] Optionally, the analog-to-digital converter ADC is a 12-bit ADC integrated in the MCU SPC5744.

[0007] Optionally, the reference voltage input terminal of the analog-to-digital converter ADC is connected to the fixed terminal of the first switch.

[0008] In a second aspect of the present disclosure, a battery management system is provided, which includes the above-mentioned temperature acquisition circuit.

[0009] In a third aspect of the present disclosure, an electric vehicle is provided, which includes the above-mentioned battery management system.

[0010] To achieve the above object, the present disclosure also provides a method for temperature acquisition, which uses the above-described temperature acquisition circuit and includes the following steps:

[0011] Switch the first switch K1 to the power supply Vcc and switch the second switch K2 to the ground terminal GND, and the analog-to-digital converter ADC acquires the first result D1;

[0012] Switch the first switch K1 to the ground terminal GND and switch the second switch K2 to the power supply Vcc, and the analog-to-digital converter ADC acquires the second result D2;

[0013] Calculate the resistance R of the temperature sensor according to the following formula NTC :

[0014]

[0015] wherein, R1 represents the resistance value of the voltage-dividing resistor;

[0016] According to the resistance R NTC Obtain the acquired temperature of the temperature sensor.

[0017] Optionally, when the reference voltage input terminal of the analog-to-digital converter ADC is connected to the fixed end of the first switch, calculate the resistance R of the temperature sensor according to the following formula NTC :

[0018]

[0019] wherein, R1 represents the resistance value of the voltage-dividing resistor.

[0020] The beneficial effects of the present disclosure are: (1) The circuit structure is simple, without the need to use a high-precision power supply, reducing costs; (2) The measurement accuracy is high, and the influence of the reference source of the analog-to-digital converter, the temperature sensor, and the accuracy of the voltage-dividing resistor can be ignored. Description of the Drawings

[0021] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0022] Figure 1 is a schematic diagram of a temperature acquisition circuit of an embodiment;

[0023] Figure 2 is a schematic diagram of a temperature acquisition circuit of another embodiment.

[0024] Description of the Reference Numerals

[0025] Power supply Vcc, ground terminal GND, voltage-dividing resistor R1, analog-to-digital converter ADC, first switch K1, second switch K2, reference voltage Vref, temperature sensor resistor R NTC 。 Specific embodiments

[0026] The following will describe the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present disclosure, and are not used to limit the present disclosure.

[0027] As Figure 1 shown, the present disclosure provides a temperature acquisition circuit, including a first switch K1, a voltage-dividing resistor R1, a temperature sensor NTC, and a second switch K2 connected in series in sequence, and further including an analog-to-digital converter ADC. One end of the analog-to-digital converter ADC is connected between the voltage-dividing resistor R1 and the temperature sensor NTC, and the other end is connected between the temperature sensor NTC and the second switch K2; both the first switch K1 and the second switch K2 are single-pole double-throw switches, and the moving terminals of the first switch K1 and the second switch K2 can both be switched between the power supply Vcc and the ground terminal GND. The fixed terminal of the first switch K1 is connected to the voltage-dividing resistor R1, and the fixed terminal of the second switch K2 is connected to the temperature sensor NTC.

[0028] Furthermore, the moving terminals of the first switch K1 and the second switch K2 are not simultaneously connected to the power supply Vcc; when the first switch K1 is connected to the power supply Vcc, the second switch K2 is connected to the ground terminal GND; when the first switch K1 is connected to the ground terminal GND, the second switch K2 is connected to Vcc, so that the current directions flowing into the temperature sensor NTC and the voltage-dividing resistor R1 are opposite, and further the analog-to-digital converter ADC obtains different measurement data.

[0029] Furthermore, in this embodiment, the analog-to-digital converter ADC selects the built-in 12-bit ADC integrated in the MCU SPC5744.

[0030] In one embodiment, as Figure 1 , the reference voltage Vref of the analog-to-digital converter ADC is only connected to the analog-to-digital converter ADC. In another embodiment, as Figure 2 , the input terminal of the reference voltage Vref of the analog-to-digital converter ADC is connected to the fixed terminal of the first switch K1, and the other output terminal is connected to the analog-to-digital converter ADC.

[0031] The present disclosure also provides a battery management system, including the above temperature acquisition circuit.

[0032] The present disclosure provides an electric vehicle, including the above battery management system.

[0033] The present disclosure also provides a temperature acquisition method, which uses the temperature acquisition circuit described above. In one implementation method, the following steps are included:

[0034] S01: Switch the first switch K1 to the power supply Vcc, and switch the second switch K2 to the ground terminal GND. Then the voltage formula collected by the analog-to-digital converter ADC is:

[0035]

[0036] Where V1 is the divided voltage of the voltage-dividing resistor R1 and the temperature sensor NTC, D1 is the result of the analog-to-digital converter ADC converting V1 into a digital quantity, n is the number of bits of the ADC, the reference voltage Vref is the reference power supply of the analog-to-digital converter ADC, and the power supply Vcc is the divided voltage power supply of the voltage-dividing resistor R1 and the temperature sensor NTC;

[0037] S02: Switch the first switch K1 to the ground terminal GND, and switch the second switch K2 to the power supply Vcc. Then the voltage formula collected by the analog-to-digital converter ADC is:

[0038]

[0039] Where V2 is the divided voltage of the voltage-dividing resistor R1 and the temperature sensor NTC, D2 is the result of the analog-to-digital converter ADC converting V2 into a digital quantity, n is the number of bits of the ADC, the reference voltage Vref is the reference power supply of the analog-to-digital converter ADC, and the power supply Vcc is the divided voltage power supply of the voltage-dividing resistor R1 and the temperature sensor NTC;

[0040] S03: Combine formulas (1) and (2), and from V1 / V2, we get:

[0041]

[0042] After simplification, we get:

[0043]

[0044] S04: Since the voltage-dividing resistor R1 is a known quantity in the circuit, and D1 and D2 are the digital quantity results collected by the analog-to-digital converter ADC. According to R NTC Look up the NTC temperature table, and the temperature corresponding to the temperature sensor NTC can be obtained. From formula (4), it can be known that the resistance R NTC of the temperature sensor NTC is related to the accuracy of the voltage-dividing resistor R1, and has nothing to do with the accuracy of the reference voltage Vref of the module converter ADC and the divided voltage power supply Vcc of the temperature sensor NTC. This greatly improves the sampling accuracy of the temperature of the temperature sensor NTC. At the same time, a high-precision power supply is not required in this circuit, which greatly reduces the system cost.

[0045] In another embodiment, the following steps are included:

[0046] S11: Switch the first switch K1 to the power supply Vcc, and switch the second switch K2 to the ground terminal GND. At the same time, connect the reference voltage Vref input terminal of the analog-to-digital converter ADC to the fixed terminal of the first switch K1. At this time, the power supplies of the analog-to-digital converter ADC, the voltage-dividing resistor R1, and the temperature sensor NTC share a Vcc, so Vcc = Vref. The voltage division formula of the voltage-dividing resistor R1 and the resistance R of the temperature sensor NTC is: NTC as follows:

[0047]

[0048] S12: Convert the analog-to-digital converter ADC into a digital quantity result. At this time, the voltage division formula is:

[0049]

[0050] where D is the result of the analog-to-digital converter ADC converting from analog quantity to digital quantity, and 2 n represents that the number of bits of the analog-to-digital converter ADC is n bits.

[0051] Combining formulas (5) and (6), we get:

[0052]

[0053] Since Vcc = Vref, simplifying formula (7) gives:

[0054]

[0055] S13: Since the voltage-dividing resistor R1 is a known quantity in the circuit and D1 is the digital quantity result collected by the analog-to-digital converter ADC, by looking up the NTC temperature table according to R NTC the temperature corresponding to the temperature sensor NTC can be obtained. From formula (8), it can be seen that the resistance R of the temperature sensor NTC NTC is related to the accuracy of the voltage-dividing resistor R1, and has nothing to do with the accuracy of the reference voltage Vref of the module converter ADC and the voltage-dividing power supply Vcc of the temperature sensor NTC. This greatly improves the sampling accuracy of the temperature of the temperature sensor NTC. At the same time, in this circuit, there is no need to use a high-precision power supply, which greatly reduces the system cost.

[0056] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0057] In addition, any combination can be made among various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A temperature acquisition circuit, characterized in that, It includes a first switch K1, a voltage-dividing resistor, a temperature sensor, and a second switch K2 connected in series in sequence. It also includes an analog-to-digital converter ADC. One end of the analog-to-digital converter ADC is connected between the voltage-dividing resistor and the temperature sensor, and the other end is connected between the temperature sensor and the second switch K2. Both the first switch K1 and the second switch K2 are single-pole double-throw switches, and the moving terminals of the first switch K1 and the second switch K2 can be switched between the power supply Vcc and the ground terminal GND. The reference voltage output terminal of the analog-to-digital converter ADC is connected to the analog-to-digital converter ADC.

2. The temperature acquisition circuit according to claim 1, characterized in that, The moving terminals of the first switch K1 and the second switch K2 are not simultaneously connected to the power supply Vcc.

3. The temperature acquisition circuit according to claim 1, characterized in that, The analog-to-digital converter ADC is a 12-bit ADC integrated in the MCU SPC5744.

4. The temperature acquisition circuit according to claim 1, characterized in that, The reference voltage input terminal of the analog-to-digital converter ADC is connected to the fixed terminal of the first switch K1.

5. A battery management system, characterized in that, It includes the temperature acquisition circuit according to any one of claims 1 to 4.

6. An electric vehicle, characterized in that, It includes the battery management system according to claim 5.

7. A method for temperature acquisition using the temperature acquisition circuit according to any one of claims 1 to 3, characterized in that, It includes the following steps: Switch the first switch K1 to the power supply Vcc and switch the second switch K2 to the ground terminal GND, and the first result D1 is obtained by the analog-to-digital converter ADC for acquisition. Switch the first switch K1 to the ground terminal GND and switch the second switch K2 to the power supply Vcc, and the second result D2 is obtained by the analog-to-digital converter ADC for acquisition. Calculate the resistance R of the temperature sensor according to the following formula NTC : R NTC = (D1 / D2) * R1, Wherein, R1 represents the resistance value of the voltage-dividing resistor. According to the resistor R NTC obtain the collected temperature of the temperature sensor.

8. The method according to claim 7, characterized in that, It also includes: When the reference voltage input terminal of the analog-to-digital converter ADC is connected to the fixed terminal of the first switch, and the reference voltage output terminal of the analog-to-digital converter ADC is connected to the analog-to-digital converter ADC, the resistance R of the temperature sensor is calculated according to the following formula NTC : R NTC = (D1 * R1) / (2 n - D1), Wherein, R1 represents the resistance value of the voltage-dividing resistor.

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