Battery monitoring chip port protection circuit, protection circuit system and battery monitoring chip port protection method

Abstract

The invention provides a port protection circuit of a battery monitoring chip, a protection circuit system and a port protection method of the battery monitoring chip, the port protection circuit of the battery monitoring chip comprises a battery cell voltage sampling unit and a port protection unit, the battery cell voltage sampling unit comprises the battery monitoring chip, and the port protection unit is connected with the battery monitoring chip. The port protection unit comprises a plurality of battery packs and a copper bar, the copper bar is used for connecting negative electrodes of the plurality of battery packs and the battery monitoring chip, the port protection unit comprises a first parallel circuit and an RC filter circuit, and the first parallel circuit and the RC filter circuit connect a negative sampling pin and a grounding pin of the battery monitoring chip in parallel. The protection circuit is used for protecting the battery monitoring chip. According to the invention, sampling of the battery monitoring chip is not affected, and the port voltage of the battery monitoring chip does not exceed a limit value.

Description

Technical Field

[0001] The present invention relates to the field of new energy electric vehicle circuits, and in particular to a port protection circuit of a battery monitoring chip, a protection circuit system, and a battery monitoring chip port protection method. Background Art

[0002] In the field of new energy vehicles, it is common for the connector to lack the negative sampling pin of the battery. It is necessary to connect the negative electrode of the battery through a jumper copper bar to ensure that the voltage at the chip port does not exceed the limit while not affecting the sampling of the battery monitoring chip. The existing technology usually connects a TVS diode in parallel at both ends of the ESD diode inside the battery monitoring chip to protect the circuit, but the TVS diode can only protect against hot plugging and cannot protect the ESD diode inside the chip. Therefore, it is necessary to further improve the circuit to ensure that the voltage at the chip port does not exceed the limit and protect the ESD diode inside the chip from being damaged. Summary of the invention

[0003] In order to solve the above-mentioned problem of keeping the port voltage of the battery monitoring chip within the working limit and protecting the ESD diode inside the chip from being damaged, the present invention provides a port protection circuit of a battery monitoring chip, including a battery cell voltage sampling unit and a port protection unit, wherein the battery cell voltage sampling unit includes a battery monitoring chip, a multi-cell battery pack and a copper busbar.

[0004] Preferably, the copper busbar is used to connect the negative electrode of the multi-cell battery pack and the battery monitoring chip.

[0005] Preferably, the port protection unit includes a first parallel circuit and an RC filter circuit, and the first parallel circuit and the RC filter circuit connect the ground pin and the negative sampling pin of the battery monitoring chip in parallel to protect the battery monitoring chip.

[0006] Preferably, the RC filter circuit comprises a first resistor and a capacitor,

[0007] Preferably, the capacitor is connected to the ground pin and the negative sampling pin, a first end of the capacitor is connected to the ground pin, a second end of the capacitor is connected to the negative sampling pin, and a first end of the first resistor is connected to the negative sampling pin.

[0008] Preferably, the first parallel circuit includes a second resistor and a second diode.

[0009] Preferably, an input end of the second diode is connected to the ground pin, and an output end of the second diode is connected to the second end of the first resistor.

[0010] Preferably, a first end of the second resistor is connected to an output end of the second diode, and a second end of the second resistor is connected to a negative electrode of the multi-cell battery pack.

[0011] Preferably, the second diode is a Schottky diode.

[0012] Preferably, the battery monitoring chip includes a first diode, and the first diode is an ESD diode inside the battery monitoring chip.

[0013] Preferably, an input end of the first diode is connected to the ground pin, and an output end of the first diode is connected to the negative sampling pin.

[0014] Preferably, the voltage difference between the ground pin and the negative sampling pin is not less than -0.3V.

[0015] Preferably, the first end of the copper busbar is connected to the ground pin, and the second end of the copper busbar is connected to the negative sampling pin.

[0016] The present invention also provides a protection circuit system, comprising the port protection circuit of any battery monitoring chip as described above.

[0017] In another aspect, the present invention further provides a battery monitoring chip port protection method, which is applied to the protection circuit system as described above.

[0018] Compared with the prior art, the above technical solution has the following beneficial effects:

[0019] 1. Ensure that the voltage difference between the negative sampling pin and the ground pin of the battery monitoring chip is not less than -0.3V;

[0020] 2. Prevent the ESD diode inside the battery monitoring chip from being damaged due to excessive voltage difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a multi-cell battery monitoring chip port protection circuit diagram of the prior art;

[0022] Figure 2 FIG. 4 is a diagram of a battery monitoring chip port protection circuit according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0023] The advantages of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0025] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0026] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0027] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0028] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0029] In actual applications, since the negative pin of the battery is often missing from the connector, a copper bar is usually used to replace the pin. When the multi-cell battery pack is discharging, the voltage V AVSS will be higher than the negative sampling pin voltage V C0 , that is, V AVSS Greater than V C0 According to the characteristics of the ESD diode inside the battery monitoring chip, V AVSS -V C0The voltage difference cannot be less than -0.3V, otherwise the ESD diode will be damaged, thereby damaging the battery monitoring chip. ESD diode (Electro-Static discharge Diode) is a diode widely used in electronic equipment. The ESD diode is connected in parallel in the circuit. When the circuit is working normally, the ESD diode is in the cut-off state and does not affect the normal operation of the circuit. When the circuit has an abnormal overvoltage and reaches the breakdown voltage of the ESD diode, it quickly changes from a high-resistance state to a low-resistance state, conducting the path, thereby protecting the IC or circuit; when the abnormal overvoltage disappears, it returns to a high-resistance state, and the circuit works normally. ESD diode damage refers to the breakdown of the diode due to external pulses. The failure modes of breakdown are short circuit and open circuit. Generally, short circuit is more likely. Short circuit means that the sampling pin of the battery monitoring chip will be short-circuited with the ground pin of the chip, so that the sampling function cannot be realized.

[0030] Since the impedance of the copper busbar is very small under normal working conditions, the voltage drop across the copper busbar will not exceed 0.3V when the current is too large. When the load changes, the copper busbar itself has parasitic inductance. According to the inductance characteristics, the inductance will always hinder the current change. According to the following formula V = L*di / dt, where di / dt is the current change rate, L is the inductance of the parasitic inductance, and V is the voltage value generated by the induced electromotive force. When other parameters remain unchanged and dt is very small, the induced electromotive force V will be very large. Therefore, if the load changes very quickly, reaching the microsecond level, a large induced electromotive force will be generated, causing V AVSS and V C0 There is a relatively large voltage difference between the two, which damages the battery monitoring chip.

[0031] See also Figure 1 , is a multi-cell battery monitoring chip port protection circuit diagram of the prior art, the copper busbar connects the ground pin of the battery monitoring chip and the negative electrode of the multi-cell battery pack, and a TVS diode is connected in parallel at both ends of the ESD diode inside the battery monitoring chip to achieve the function of protecting the circuit, but this method can only protect against hot plugging. TVS diodes (Transient Voltage Suppressors) are devices with a single PN junction or multiple PN junctions integrated using semiconductor technology. Hot plugging, that is, plugging with power on, allows users to remove and replace damaged electronic components without cutting off the power supply, thereby improving the system's timely recovery capability, scalability and flexibility. Therefore, the prior art cannot ensure that the voltage difference between the ground pin and the negative sampling pin of the battery monitoring chip is less than the limit value after the circuit is powered on, and cannot protect the ESD diode inside the battery monitoring chip.

[0032] See also Figure 2, is a multi-cell battery monitoring chip port protection circuit diagram in accordance with a preferred embodiment of the present invention. The battery monitoring chip AFE (Active Front End) port protection circuit includes a battery cell voltage sampling unit and a port protection unit, and the battery cell voltage sampling unit includes a battery monitoring chip AFE, a multi-cell battery pack and a copper busbar.

[0033] The port protection unit includes a first parallel circuit and an RC filter circuit, wherein the first parallel circuit and the RC filter circuit connect a ground pin and a negative sampling pin of the battery monitoring chip AFE in parallel to protect the battery monitoring chip AFE.

[0034] The RC filter circuit includes a first resistor R1 and a capacitor C1, the capacitor C1 connects the ground pin and the negative sampling pin in parallel, the first end of the capacitor C1 is connected to the ground pin, the second end of the capacitor C1 is connected to the negative sampling pin, and the first end of the first resistor R1 is connected to the negative sampling pin; the first parallel circuit includes a second resistor R2 and a second diode D2, the input end of the second diode D2 is connected to the ground pin, and the output end of the second diode D2 is connected to the second end of the first resistor R1; the first end of the second resistor R2 is connected to the output end of the second diode D2, and the second end of the second resistor R2 is connected to the negative electrode of the multi-cell battery pack.

[0035] The RC filter resistor in the prior art is changed to a first resistor R1 and a second resistor R2, and the resistance value remains unchanged. The second diode D2 uses a Schottky diode with a small reverse leakage current and a relatively small voltage drop, so that the reverse leakage current can be kept within 10uA in the full temperature range, otherwise it will affect the normal single-cell sampling accuracy. The second diode D2 is connected in parallel at both ends of the RC filter circuit, and the output end of the second diode D2 is connected to the first end of the second resistor R2. The second resistor R2 is used to limit the current to prevent the second diode D2 from being damaged.

[0036] The first resistor R1 has a certain current limiting effect on the first diode D1 inside the battery monitoring chip AFE and shares part of the voltage drop. The resistor R2 has a certain current limiting effect on the external Schottky diode and also shares part of the voltage drop.

[0037] The battery monitoring chip AFE includes a first diode D1, which is an ESD diode inside the battery monitoring chip AFE; an input end of the first diode D1 is connected to the ground pin, and an output end of the first diode D1 is connected to the negative sampling pin.

[0038] Connecting the second diode D2 in parallel at both ends of the first diode D1 can play a shunting role, thereby improving the high pulse resistance performance of the first diode D1, and the voltage drop of the second diode D2 cannot exceed 0.3V in the full temperature range, otherwise it cannot protect the first diode D1 inside the chip. According to the characteristics of the diode, the smaller the voltage drop, the greater the reverse leakage current, and excessive reverse leakage current will affect the sampling accuracy.

[0039] The present invention also discloses a protection circuit system and a battery monitoring chip port protection method, wherein the protection circuit system includes the port protection circuit of the battery monitoring chip AFE as described above, and the battery monitoring chip port protection method can be applied to the protection circuit system as described above. After adopting the present invention, it can ensure that the voltage difference between the negative sampling pin and the ground pin of the battery monitoring chip does not exceed the limit value without affecting the sampling of the battery monitoring chip, thereby effectively protecting the ESD diode therein.

[0040] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A port protection circuit for a battery monitoring chip, characterized in that: Including battery cell voltage sampling unit and port protection unit, The cell voltage sampling unit includes a battery monitoring chip, a multi-cell battery pack and a copper busbar; The copper busbar is used to connect the negative electrode of the multi-cell battery pack and the battery monitoring chip; The port protection unit includes a first parallel circuit and an RC filter circuit. The first parallel circuit and the RC filter circuit connect the ground pin and the negative sampling pin of the battery monitoring chip in parallel to protect the battery monitoring chip.

2. The port protection circuit of the battery monitoring chip according to claim 1, characterized in that: The RC filter circuit includes a first resistor and a capacitor, The capacitor is connected to the ground pin and the negative sampling pin, a first end of the capacitor is connected to the ground pin, a second end of the capacitor is connected to the negative sampling pin, and a first end of the first resistor is connected to the negative sampling pin; The first parallel circuit includes a second resistor and a second diode, An input end of the second diode is connected to the ground pin, and an output end of the second diode is connected to the second end of the first resistor; A first end of the second resistor is connected to an output end of the second diode, and a second end of the second resistor is connected to a negative electrode of the multi-cell battery pack.

3. The port protection circuit of the battery monitoring chip according to claim 2, characterized in that: The second diode is a Schottky diode.

4. The port protection circuit of the battery monitoring chip as claimed in claim 1, characterized in that: The battery monitoring chip includes a first diode, and the first diode is an ESD diode inside the battery monitoring chip; An input end of the first diode is connected to the ground pin, and an output end of the first diode is connected to the negative sampling pin.

5. The port protection circuit of the battery monitoring chip according to claim 1, characterized in that: A first end of the copper busbar is connected to the ground pin, and a second end of the copper busbar is connected to the negative sampling pin.

6. The port protection circuit of the battery monitoring chip according to claim 1, characterized in that: The voltage difference between the ground pin and the negative sampling pin is not less than -0.3V.

7. A protection circuit system, characterized in that: A port protection circuit comprising any battery monitoring chip as claimed in claims 1-6.

8. A battery monitoring chip port protection method, characterized in that: Applicable to the protection circuit system as claimed in claim 7.

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