Battery health state detection circuit and vehicle-mounted communication terminal

Abstract

The utility model discloses a battery health state detection circuit and a vehicle-mounted communication terminal, and relates to the technical field of automobile electronic circuits. The battery health state detection circuit comprises a standby battery, a voltage acquisition module, a microcontroller MCU, a switch control module and a discharge path module. The output end of the standby battery is respectively connected with the voltage acquisition module and the discharge path module, the microcontroller MCU is respectively connected with the voltage acquisition module and the switch control module, the switch control module is respectively connected with the microcontroller MCU and the discharge path module, the voltage acquisition module acquires the voltage value of the standby battery, and the discharge path module outputs the voltage value of the standby battery. And the voltage information of the current standby battery is obtained by inputting the voltage information into the MCU. Discharging of the standby battery is controlled by building a specific circuit, the SOH of the standby battery is evaluated and calculated in combination with the internal resistance information of the standby battery and the voltage information, collected by the voltage collection module, of the standby battery, the scheme is simple and easy to implement, and the cost is low.

Description

Technical Field

[0001] The utility model of the present application relates to the technical field of automotive electronic circuits, and particularly relates to a battery health state detection circuit and a vehicle-mounted communication terminal. Background Art

[0002] In a vehicle-mounted telematics terminal, namely a T-BOX (Telematics BOX), which is a vehicle-mounted communication terminal including functions such as emergency call, remote vehicle control, data reporting, and positioning. It is required to be powered by a backup battery in case of an emergency such as the main power supply being disconnected or the main power supply voltage being too low. And the SOH (State of Health) of this backup battery needs to be reported to the client at any time to remind the user whether the battery needs to be replaced.

[0003] Most of the usual SOH estimations adopt integrated ICs, such as the lithium battery power monitoring and metering IC BQ27542 of TI. This solution of using an integrated IC to monitor and report the SOH of the backup battery has a relatively high cost, is relatively complex to implement, and is subject to the risk of the supply chain. Summary of the Utility Model

[0004] In view of this, an object of the embodiments of the utility model of the present application is to provide a battery health state detection circuit. The battery health state detection circuit evaluates the health state of the backup battery by controlling the discharge of the backup battery, combining the internal resistance information of the backup battery and the collected battery voltage information, with low cost and easy to implement.

[0005] The technical solution adopted by the present utility model to solve the above technical problems is as follows:

[0006] According to an aspect of the embodiments of the present utility model, a battery health state detection circuit is provided, including a backup battery, a voltage acquisition module, a microcontroller MCU, a switch control module, and a discharge path module;

[0007] The output end of the backup battery is respectively connected to the voltage acquisition module and the discharge path module. The microcontroller MCU is respectively connected to the voltage acquisition module and the switch control module. The switch control module is respectively connected to the microcontroller MCU and the discharge path module. The voltage acquisition module acquires the voltage value of the backup battery and inputs it to the microcontroller MCU to obtain the voltage information of the current backup battery.

[0008] Among them, the voltage acquisition module includes a resistor R101, a resistor R102, and a capacitor C101. The resistor R102 and the capacitor C101 are connected in parallel, one end of which is connected to the resistor R101 and the microcontroller MCU, and the other end is grounded; one end of the resistor R101 is connected to the backup battery and the discharge path module, and the other end is connected to the resistor R102, the capacitor C101, and the microcontroller MCU.

[0009] Among them, the microcontroller MCU has two GPIOs, which are respectively connected to the voltage acquisition module and the switch control module. One GPIO of the microcontroller connected to the voltage acquisition module has an ADC function to collect the voltage output by the voltage acquisition module; the other GPIO of the microcontroller MCU connected to the switch control module controls the opening and closing of the switch control module by outputting high and low levels.

[0010] Among them, the switch control module includes a second switch, a resistor R105, a resistor R107, and a capacitor C103.

[0011] Among them, the discharge path module includes a first switch, a resistor R103, a resistor R104, a resistor R106, a resistor R108, a capacitor C102, and a third switch.

[0012] Among them, the first switch is a PNP triode VT101, and the third switch is a PMOS VT103.

[0013] Among them, the second switch is a PNP triode VT102. One GPIO terminal of the microcontroller MCU is connected to the base of the PNP triode VT102 through a resistor R105 to control the conduction and closing of the PNP triode VT102; the base of the PNP triode VT102 is grounded through a connecting resistor R107. The resistor R107 is connected in parallel with a capacitor C103. The base of the PNP triode VT102 is grounded through the connecting capacitor C103. The emitter of the PNP triode VT102 is grounded. The collector of the PNP triode VT102 is connected to the gate G of the PMOS VT103 through a resistor R108.

[0014] Among them, the emitter of the PNP transistor VT101 is connected to the backup battery, the base of the PNP transistor VT101 is connected to the source S of the PMOS VT103 through the resistor R104, the collector of the PNP transistor VT101 is connected to the source S of the PMOS VT103 through the resistor R106, and a capacitor C102 is connected in parallel with the circuit R106. One end of the capacitor C102 is connected to the resistor R106 and the collector of the PNP transistor VT101, and the other end is electrically connected to the source S of the PMOS VT103; the collector of the PNP transistor VT101 is also electrically connected to the gate G of the PMOS VT103.

[0015] Among them, the backup battery is respectively connected to the first switch and the resistor R103, and is connected to the third switch through the resistor R103; the first switch is also connected to the third switch through the resistor R104.

[0016] This application also provides a vehicle-mounted communication terminal, including the battery health state detection circuit described above.

[0017] Compared with the prior art, most of the SOH estimations of the backup battery adopt the scheme of using an integrated IC to monitor and report the SOH of the backup battery, which has a relatively high cost, a relatively complex implementation scheme, and the problem of being restricted by the supply chain. The battery health state detection circuit described in the embodiments of this application controls the discharge of the backup battery by building a specific circuit, and combines the internal resistance information of the backup battery and the voltage information of the backup battery collected by the voltage acquisition module to evaluate and calculate the SOH of the backup battery. The scheme is simple and easy to implement, and has a low cost. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

[0019] Figure 1 It is a structural block diagram of a battery health state detection circuit according to an embodiment of the present invention;

[0020] Figure 2 It is an equivalent relationship diagram of the battery health state and the battery internal resistance according to an embodiment of the present invention;

[0021] Figure 3 It is a circuit schematic diagram of a battery health state detection circuit according to an embodiment of the present invention. Detailed Embodiments

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer and more understandable, the following further details the present utility model in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not used to limit the present utility model.

[0023] Embodiment 1

[0024] Please refer to Figure 1 、 Figure 2 and in combination with Figure 3 as shown, an embodiment of the present application provides a battery health state detection circuit. The battery health state detection circuit includes a backup battery 10, a voltage acquisition module 20, a microcontroller MCU 30, a switch control module 40, and a discharge path module 50. The output end of the backup battery 10 is respectively connected to the voltage acquisition module 20 and the discharge path module 50. The microcontroller MCU 30 is respectively connected to the voltage acquisition module 20 and the switch control module 40. The switch control module 40 is respectively connected to the microcontroller MCU 30 and the discharge path module 50. When the main power supply is powered off or the main power supply voltage is too low, the backup battery 10 supplies power to the vehicle-mounted terminal.

[0025] In one embodiment, the backup battery 10 uses a nickel-metal hydride battery.

[0026] Please refer to Figures 1 to 3 , which is a battery health state detection circuit provided by an embodiment of the present utility model and is applied to a vehicle-mounted terminal, such as a vehicle-mounted OBD, a fire safety warning system, a communication base station, etc., for detecting the SOH (State of Health) of the backup battery on the device. Only the parts related to this embodiment are shown for the convenience of description.

[0027] The voltage acquisition module 20 is connected to the backup battery 10. The voltage acquisition module 20 acquires the voltage value of the backup battery 10 and inputs it to the ADC interface of the microcontroller MCU 30, and the microcontroller MCU 30 obtains and judges the current voltage information of the backup battery 10.

[0028] In this embodiment, the voltage acquisition module 20 includes a resistor R101, a resistor R102, and a capacitor C101. The resistor R102 is connected in parallel with the capacitor C101. One end of the resistor R102 is connected to the resistor R101 and the microcontroller MCU 30, and the other end is grounded. One end of the resistor R101 is connected to the backup battery 10 and the discharge path module, and the other end is connected to the resistor R102, the capacitor C101, and the microcontroller MCU 30. In this embodiment, the resistor R101 and the resistor R102 form a voltage division circuit. After the output voltage of the backup battery is divided by the resistor R101 and the resistor R102, the maximum voltage value input to the MCU is less than the input threshold of the MCU. In the embodiment of the present application, the function of the capacitor C101 is to filter and debounce.

[0029] The microcontroller MCU 30 is the main control component of the T-BOX. The microcontroller MCU 30 has two GPIOs (General Purpose Input Output), and these two GPIOs are respectively connected to the voltage acquisition module 20 and the switch control module 40. One GPIO connected to the microcontroller 30 and the voltage acquisition module 20 has ADC function and can acquire the voltage output by the voltage acquisition module 20; the other GPIO connected to the microcontroller MCU 30 and the switch control module 40 controls the opening and closing of the switch control module 40 by outputting high and low levels.

[0030] The switch control module 40 is controlled to be opened or closed by the high and low levels input from the GPIO terminal of the microcontroller MCU 30. According to the characteristics of the battery, the SOH of the backup battery does not need to be collected at all times. In order to reduce power consumption, the discharge path module 50 only needs to be opened or closed according to requirements. When the switch is opened, the backup battery 10 discharges through the discharge path module 50, and when it is closed, the discharge path module 50 does not discharge.

[0031] In one embodiment, the switch control module 40 includes a second switch, a resistor R105, a resistor R107, and a capacitor C103. In this embodiment, the second switch is a PNP triode VT102. Specifically, in this embodiment, the GPIO terminal of the microcontroller MCU is connected to the base of the PNP triode VT102 through the resistor R105 to control the conduction and closing of the PNP triode VT102. The base of the PNP triode VT102 is grounded through the connection resistor R107. The resistor R107 is connected in parallel with the capacitor C103. The base of the PNP triode VT102 is grounded through the connection capacitor C103. The emitter of the PNP triode VT102 is grounded. The collector of the PNP triode VT102 is connected to the gate G of the PMOS VT103 through the resistor R108.

[0032] When the switch control module 40 works, when the microcontroller MCU 30 outputs a high level, the PNP triode VT102 conducts, and when it conducts, it controls to turn on the discharge path module 50. When the microcontroller MCU outputs a low level, the PNP triode VT102 cuts off, and the discharge path module 50 is turned off. In this embodiment, whether the discharge path module 50 works is controlled by controlling the conduction and cut-off of the second switch of the switch control module 40. In the embodiment of the present application, the resistor R105, the resistor R107, and the capacitor C103 play a role in protection and filtering in this circuit.

[0033] In one embodiment, the discharge path module 50 includes a first switch, a resistor R103, a resistor R104, a resistor R106, a resistor R108, a capacitor C102, and a third switch. In this embodiment, the first switch is the PNP triode VT101, and the third switch is the PMOS VT103.

[0034] The backup battery 10 is respectively connected to the first switch and the resistor R103, and is connected to the third switch through the resistor R103. The first switch is connected to the third switch through the resistor R104. Specifically, in this embodiment, the emitter of the PNP triode VT101 is connected to the backup battery 10, the base of the PNP triode VT101 is connected to the source S of the PMOS VT103 through the resistor R104, the collector of the PNP triode VT101 is connected to the source S of the PMOS VT103 through the resistor R106, the circuit R106 is connected in parallel with the capacitor C102, one end of the capacitor C102 is connected to the resistor R106 and the collector of the PNP triode VT101, and the other end is electrically connected to the source S of the PMOS VT103. The collector of the PNP triode VT101 is also electrically connected to the gate G of the PMOS VT103.

[0035] In the embodiment of the present application, the discharge path module 50 is connected to the backup battery 10, and the switch of the switch control module 40 controls whether the discharge path module 50 works. The principle of estimating the battery SOH applied in the embodiment of the present application is to detect the internal resistance of the backup battery, and the specific working principle is as follows.

[0036] When the switch control module 40 is closed, the PMOS VT103 is closed, and the microcontroller MCU 30 collects the voltage value V0 of the backup battery 10 at this time through the voltage acquisition module 20; when the switch control module 40 is opened, the PMOS VT103 is opened for discharging, and at this time the PMOS works in the saturation region. Utilizing the conduction characteristic of the PNP triode, the voltage drop Veb is about 0.7V when it conducts, and at this time the discharge current I = 0.7 / R103.

[0037] Preferably, in the discharge path module 50, the triode VT101 and R103 limit the magnitude of the discharge current, that is, the current magnitude is approximately 0.7 / R103; R104 is the base protection resistor of the triode VT101; the resistors R106 and R108 limit the gate voltage when the PMOS VT103 conducts and turns off, and the capacitor C102 is a soft-start capacitor to prevent excessive current at the moment of startup. When the switch control module 40 is turned on, the voltage acquisition module 20 acquires the voltage V1 at this time.

[0038] When estimating the internal resistance r of the battery at a certain moment, the switch control module disconnects the discharge path, the voltage acquisition module acquires the voltage V0, turns on the discharge path, and acquires the voltage V1. Since the discharge path has a fixed discharge current I,

[0039] At this time, according to the internal resistance r of the backup battery = (V1 - V0) / I = (V1 - V0)*R103 / 0.7; Formula (1)

[0040] Furthermore, since the initial resistance r0 and the end-of-life resistance r1 of the backup battery are inherent characteristic values of the battery, as Figure 2 shown, according to the linear relationship between the internal resistance and the life of the nickel-metal hydride battery, it can be obtained that: (r1 - r0) / 100% = (r - r0) / SOH, and further it can be obtained that:

[0041] SOH = 100%*(r - r0) / (r1 - r0), Formula (2)

[0042] Substituting the above formula (1) for the internal resistance r of the backup battery = (V1 - V0) / I = (V1 - V0)*R103 / 0.7 into the above formula (2) can further obtain:

[0043] SOH = ((V1 - V0)*R103 - 0.7r0) / 0.7(r1 - r0) Formula (3)

[0044] Thus, the state of health SOH of the battery can be calculated.

[0045] Among them, the meanings of the parameters in Formula (3) are as follows:

[0046] r0 is the initial resistance of the backup battery;

[0047] r1 is the end-of-life resistance of the backup battery;

[0048] V0 is the voltage value V0 of the backup battery 10 acquired by the voltage acquisition module 20 when the switch control module 40 is turned off;

[0049] V1 is the voltage value V1 acquired by the voltage acquisition module 20 when the switch control module 40 is turned on.

[0050] In the SOH estimation method described in the embodiments of the present application, according to the characteristics of nickel-metal hydride batteries (in this embodiment, the backup battery uses nickel-metal hydride batteries), the nominal initial internal resistance r0, the terminal internal resistance r1, and the initial capacity c0 of the backup battery are known when it leaves the factory. As the backup battery is used, the raw materials of the backup battery gradually deteriorate, and the internal resistance of the battery gradually increases. When the capacity of the backup battery becomes 80% * c0, it can be determined that the battery life is exhausted. At this time, there is a corresponding internal resistance r1, and both r0 and r1 are known parameters of the battery. Through the above formula and related fixed parameters, the state of health SOH of the backup battery can be simply calculated. The method is simple to implement and has low cost.

[0051] The state of health detection circuit of the backup battery described in the embodiments of the present application controls the discharge of the backup battery by building a specific circuit, and combines the internal resistance information of the backup battery and the voltage information of the backup battery collected by the voltage acquisition module 20 to evaluate and calculate the SOH of the backup battery. The solution is simple and easy to implement, and has low cost.

[0052] The application of the state of health detection circuit of the backup battery provided in the embodiments of the present invention in a vehicle-mounted terminal is also applicable to other applications powered by backup batteries, such as OBD products, communication base stations, etc.

[0053] Embodiment 2

[0054] The embodiments of the present application also provide a vehicle-mounted communication terminal, which includes a state of health detection circuit of the backup battery. The state of health detection circuit of the backup battery is described in detail in Embodiment 1 and will not be elaborated here.

[0055] Compared with the estimation of the state of health detection circuit in the existing vehicle-mounted terminals, which all require the use of specific integrated ICs, the cost is relatively high and the solution is relatively complex. The state of health detection circuit in the vehicle-mounted terminal described in the present application controls the discharge of the backup battery by building a specific circuit, and combines the internal resistance information of the backup battery and the voltage information of the backup battery collected by the voltage acquisition module 20 to evaluate the SOH of the backup battery. The solution is simple and easy to implement, and has low cost.

[0056] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. However, the scope of the present invention is not limited thereby. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the present invention shall fall within the scope of the present invention.

Claims

1. A battery health state detection circuit, characterized in that, It includes a backup battery, a voltage acquisition module, a microcontroller MCU, a switch control module, and a discharge path module; the output terminal of the backup battery is respectively connected to the voltage acquisition module and the discharge path module, the microcontroller MCU is respectively connected to the voltage acquisition module and the switch control module, the switch control module is respectively connected to the microcontroller MCU and the discharge path module, and the voltage acquisition module acquires the voltage value of the backup battery and inputs it to the microcontroller MCU to obtain the current voltage information of the backup battery.

2. The battery health state detection circuit according to claim 1, wherein, The voltage acquisition module includes a resistor R101, a resistor R102, and a capacitor C101. The resistor R102 is connected in parallel with the capacitor C101, one end of which is connected to the resistor R101 and the microcontroller MCU, and the other end is grounded; one end of the resistor R101 is connected to the backup battery and the discharge path module, and the other end is respectively connected to the resistor R102, the capacitor C101, and the microcontroller MCU.

3. The battery health state detection circuit according to claim 2, wherein The microcontroller MCU has two GPIOs, which are respectively connected to the voltage acquisition module and the switch control module. One GPIO of the microcontroller connected to the voltage acquisition module has ADC function to acquire the voltage output by the voltage acquisition module; the other GPIO of the microcontroller MCU connected to the switch control module controls the opening and closing of the switch control module by outputting high and low levels.

4. The battery health state detection circuit according to claim 3, wherein The switch control module includes a second switch, a resistor R105, a resistor R107, and a capacitor C103.

5. The battery health state detection circuit according to claim 4, wherein The discharge path module includes a first switch, a resistor R103, a resistor R104, a resistor R106, a resistor R108, a capacitor C102, and a third switch.

6. The battery health state detection circuit according to claim 5, wherein, The first switch is a PNP triode VT101, and the third switch is a PMOS VT103.

7. The battery health state detection circuit according to claim 6, wherein, The second switch is a PNP triode VT102. One GPIO terminal of the microcontroller MCU is connected to the base of the PNP triode VT102 through a resistor R105 to control the conduction and closing of the PNP triode VT102; the base of the PNP triode VT102 is grounded through a connecting resistor R107, and a capacitor C103 is connected in parallel with the resistor R107. The base of the PNP triode VT102 is grounded through the connecting capacitor C103. The emitter of the PNP triode VT102 is grounded, and the collector of the PNP triode VT102 is connected to the gate G of the PMOS VT103 through a resistor R108.

8. The battery health state detection circuit according to claim 6, wherein, The emitter of the PNP transistor VT101 is connected to the backup battery. The base of the PNP transistor VT101 is connected to the source S of the PMOS VT103 through the resistor R104. The collector of the PNP transistor VT101 is connected to the source S of the PMOS VT103 through the resistor R106. A capacitor C102 is connected in parallel with the circuit R106. One end of the capacitor C102 is connected to the resistor R106 and the collector of the PNP transistor VT101, and the other end is electrically connected to the source S of the PMOS VT103. The collector of the PNP transistor VT101 is also electrically connected to the gate G of the PMOS VT103.

9. The battery health state detection circuit according to claim 6, wherein The backup battery is respectively connected to the first switch and the resistor R103, and is connected to the third switch through the resistor R103. The first switch is also connected to the third switch through the resistor R104.

10. A vehicle-mounted communication terminal, characterized in that, It includes the battery health status detection circuit according to any one of claims 1-9.

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