A power supply circuit for collecting voltage of any battery

Abstract

The present invention provides a power supply circuit for collecting voltage of any battery cell, comprising an LTC‑68xx series chip, a diode module, an isolated power supply module and an external power supply, wherein the external power supply is connected to the input end of the isolated power supply module, the negative output end of the isolated power supply module is connected to the diode module, the positive output end of the isolated power supply module is connected to the pin V+ of the LTC‑68xx series chip; the pin V‑ of the LTC‑68xx series chip is connected to the pin BAT0; the diode modules are respectively connected to the LTC‑68xx series chips; the output end voltage of the isolated power supply module is greater than the input battery string voltage and is less than or equal to 70V; cumbersome repeated wiring is avoided, and the design goal is achieved with only a very small cost.

Description

[Technical field]

[0001] The invention relates to a power supply circuit for collecting voltage of any battery cell. [Background technology]

[0002] The Ltc68xx (such as 6804, 6811) series detection chips developed by Linear Technology Corporation are currently widely used in lithium battery detection applications. The chip has the ability to measure 12 battery strings at the same time, can support stacking up to hundreds of battery strings, and has the characteristics of fast measurement speed and small measurement error. A single chip can complete the measurement of 12 battery strings within 290uS, with a maximum error of 1.2mV.

[0003] When using Ltc-68xx (such as 6811) series chips, the power pin must be greater than 11V and not less than the total input battery string voltage, and the maximum value should not exceed 70V, otherwise it will cause chip overvoltage failure. Generally, the chip power supply is taken from the positive electrode of the acquisition battery pack. If the acquisition quantity is determined (used in fixed acquisition occasions), the chip power supply is easy to determine. However, when the number of collected batteries is uncertain (used for mobile non-fixed number acquisition), the chip power supply voltage (V+\V-) is uncertain, and the power supply voltage input will be difficult to design; such as Figure 1 As shown, it is the acquisition of a fixed number of battery strings.

[0004] like Figure 2 As shown, the current method of use is to design a switching power supply separately, with the maximum number of cells as the upper limit voltage, such as setting the output voltage to 55V and the power design to 1-2W. In this way, users can complete the collection by connecting 1-12 cells. This design method requires a power supply circuit to be specially designed on the PCB (the transformer needs to be customized), which takes up PCB area, requires a large number of electronic components, and is not conducive to the miniaturization of the product. Using this method will complicate the system design and increase the cost.

[0005] There is another method of use. When the number of battery cells is more than 12, the chip power supply adopts the official recommended method. For example, if there are 15 battery cells in total, chip 1 is connected to cells 1 to 12, and chip 2 is connected to cells 4 to 15. This method is widely used in BMS battery collection; the problem is that the external wiring needs to be repeated, which wastes wires, accessories and labor, and is inefficient. [Summary of the invention]

[0006] The technical problem to be solved by the present invention is to provide a power supply circuit for collecting the voltage of any battery cell, thereby avoiding cumbersome repeated wiring and achieving the design goal at only a very small cost.

[0007] The present invention is implemented as follows: a power supply circuit for collecting voltage of any battery cell, comprising an LTC-68xx series chip, a diode module, an isolation power module and an external power supply, wherein the external power supply is connected to the input end of the isolation power module, the negative output end of the isolation power module is connected to the diode module, the positive output end of the isolation power module is connected to the pin V+ of the LTC-68xx series chip; the pin V- of the LTC-68xx series chip is connected to the pin BAT0;

[0008] The diode modules are respectively connected to the LTC-68xx series chips, so that the output voltage of the isolation power module is greater than the input battery string voltage and is less than or equal to 70V.

[0009] Further, the diode module includes a diode D1, a diode D2, a diode D3 and a diode D4, and the cathode of the diode D1, the cathode of the diode D2, the cathode of the diode D3 and the cathode of the diode D4 are connected in parallel to the negative output terminal of the isolation power module;

[0010] The anode of the diode D1 is connected to the pin BAT0 of the LTC-68xx series chip;

[0011] The anode of the diode D2 is connected to the pin BAT4 of the LTC-68xx series chip;

[0012] The anode of the diode D3 is connected to the pin BAT7 of the LTC-68xx series chip;

[0013] The anode of the diode D4 is connected to the pin BAT10 of the LTC-68xx series chip.

[0014] Furthermore, the isolated power supply module is a 15V isolated power supply chip.

[0015] The advantages of the present invention are: the power supply circuit for collecting the voltage of any battery cell of the present invention eliminates the need for a customized switching power supply, can share the same external power supply with the MCU, avoids cumbersome repeated wiring, and achieves the design goal at only a very low cost.

Brief Description of the Drawings

[0016] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0017] Figure 1 It is a circuit diagram of an existing fixed number of battery string acquisition circuit.

[0018] Figure 2 The invention is a circuit diagram of an existing acquisition circuit using an upper limit voltage setting.

[0019] Figure 3 The invention discloses a circuit diagram of a power supply circuit for collecting voltage of any battery cell. [Specific implementation method]

[0020] The embodiment of the present invention solves the technical problems in the prior art that external wiring needs to be repeated, which wastes wires, accessories and labor and has low efficiency by providing a power supply circuit for collecting the voltage of any battery cell. It avoids cumbersome repeated wiring and achieves the technical effect of the design goal at only a very low cost.

[0021] The technical solution in the embodiment of the present invention is to solve the above problems, and the overall idea is as follows:

[0022] The power design of this device requires that the input voltage of V+\V- must be higher than 11V, and the power supply voltage must be higher than the voltage of the connected battery string. Since the upper limit of the charging voltage of a single string of lithium batteries is 4.2V, and the maximum voltage of 3 strings of batteries is 12.6V, in order to ensure that the input voltage is higher than 11V, a 15V power supply voltage is designed to be connected in series to several specific battery strings. Several battery strings with specific numbers are connected in parallel using diodes to ensure that the potential at this point can change with the number of connected battery strings. After adding the 15V voltage in series, the voltage of V+ will be higher than the voltage of the actual connected battery string. The power input conditions of the IC are met and it can work normally.

[0023] like Figure 3 As shown, the external power supply is used to power the entire system circuit, including the MCU and data communication power supply. Because the LCT68xx series IC needs to share the negative terminal with the battery, this power supply cannot be used and is handled separately. The external power supply voltage is generally 12V or 15V. After the power supply is input into the system, the auxiliary power supply circuit generates the low voltage required by the MCU, or other voltages, to complete the power distribution. The auxiliary power supply is the power supply that meets the working needs of the detection system and is used for the circuit board PCBA; the role of the four diodes is to make the voltage value after parallel connection always automatically track the voltage of the battery with the highest voltage. For example, if only 4 batteries are connected, the voltage after parallel connection is 3.7V*4=14.8V, and if only 7 batteries are connected, the voltage after parallel connection is 3.7*7=25.9V, in order to achieve voltage following at this point.

[0024] The present invention uses an external input power source as a power source to generate an isolated 15V voltage. The battery strings with specific numbers are connected in parallel through diodes and then connected in series with the 15V voltage to form a total power input V+.

[0025] For example, when a total of 6 batteries are connected, because BAT4 is connected to the front end of the diode, the voltage at VA is 3.7*4-0.7=14.1V. After adding the 15V power supply in series, the voltage of V+ is 14.1+15=29.1V, and the voltage of 6 strings is 22.2V. Because 29.1>22.2>11V, the power supply working conditions of the IC are met, and LTC68xx can collect the battery voltage normally.

[0026] In this article, BTB represents a battery string. BTBn is the number of a battery in the whole group.

[0027] BAT0 is connected to the negative pole of the battery string, BAT1 is the positive pole of the first battery string, and BAT2 is the positive pole of the second battery string. The dotted line in the figure describes the correspondence between the battery string and the IC pin. If there are only four batteries, the battery string pins need to be connected to BAT0, BAT1, BAT2, BAT3, and BAT4 in sequence. The wiring method of the 7-battery string is the same as the wiring method of the 4-battery string.

[0028] Other situations are analyzed as follows:

[0029] When the number of batteries is greater than or equal to 1 string and less than 4 strings, the operating voltage V+ is 15V-VD1, which can meet the device working conditions;

[0030] When the number of batteries is greater than or equal to 4 and less than 7, the operating voltage V+ is BAT4+15V-VD2;

[0031] When the number of batteries is greater than or equal to 7 and less than 10, the operating voltage V+ is BAT7+15V-VD3;

[0032] When the number of batteries is greater than or equal to 10 to 12, the operating voltage V+ is BAT10+15V-VD4;

[0033] D1-D4 are common rectifier diodes. In this article, VD1-DV4 is the diode conduction voltage drop, which is generally 0.7V; VD1-VD4 represents the diode conduction voltage drop; BAT4\BAT7\BAT10 represent the voltage values ​​of the 4th, 7th and 10th strings respectively.

[0034] The 15V isolated power module can be directly purchased from a 1W DCDC switching power module. This module uses a SIP-4 package, is cheap, takes up very little PCB space, and the material does not need to be customized and processed separately.

[0035] By powering the chip in this way, the chip's operating voltage range can always be met.

[0036] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0037] Please refer to Figure 3, a power supply circuit for collecting voltage of any battery cell of the present invention includes an LTC-68xx series chip, a diode module, an isolation power module and an external power supply, wherein the external power supply is connected to the input end of the isolation power module, the negative output end of the isolation power module is connected to the diode module, and the positive output end of the isolation power module is connected to the pin V+ of the LTC-68xx series chip; the pin V- of the LTC-68xx series chip is connected to the pin BAT0;

[0038] The diode modules are respectively connected to the LTC-68xx series chips, so that the output voltage of the isolation power module is greater than the input battery string voltage and is less than or equal to 70V.

[0039] In another embodiment of the present invention, the diode module includes a diode D1, a diode D2, a diode D3 and a diode D4, and the cathode of the diode D1, the cathode of the diode D2, the cathode of the diode D3 and the cathode of the diode D4 are connected in parallel to the negative output terminal of the isolation power module;

[0040] The anode of the diode D1 is connected to the pin BAT0 of the LTC-68xx series chip;

[0041] The anode of the diode D2 is connected to the pin BAT4 of the LTC-68xx series chip;

[0042] The anode of the diode D3 is connected to the pin BAT7 of the LTC-68xx series chip;

[0043] The anode of the diode D4 is connected to the pin BAT10 of the LTC-68xx series chip.

[0044] The isolated power supply module is a 15V isolated power supply chip; through the above implementation, its cost is minimized. The external power supply used by the LTC-68xx series chip is shared with the MCU, and there is no need to reconnect an external power supply.

[0045] According to the voltage of the isolation power module, the number of diodes can be selected and then connected, as long as the output voltage of the isolation power module is greater than the input battery string voltage and is less than or equal to 70V.

[0046] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A power supply circuit for collecting voltage of any battery cell, characterized in that: It includes an LTC-68xx series chip, a diode module, an isolated power module and an external power supply, wherein the external power supply is connected to the input end of the isolated power module, the negative output end of the isolated power module is connected to the diode module, the positive output end of the isolated power module is connected to the pin V+ of the LTC-68xx series chip; the pin V- of the LTC-68xx series chip is connected to the pin BAT0; The diode modules are respectively connected to the LTC-68xx series chips, so that the output voltage of the isolation power module is greater than the input battery string voltage and is less than or equal to 70V.

2. A power supply circuit for collecting voltage of any battery cell as claimed in claim 1, characterized in that: The diode module includes a diode D1, a diode D2, a diode D3 and a diode D4, and the cathode of the diode D1, the cathode of the diode D2, the cathode of the diode D3 and the cathode of the diode D4 are connected in parallel to the negative output terminal of the isolation power module; The anode of the diode D1 is connected to the pin BAT0 of the LTC-68xx series chip; The anode of the diode D2 is connected to the pin BAT4 of the LTC-68xx series chip; The anode of the diode D3 is connected to the pin BAT7 of the LTC-68xx series chip; The anode of the diode D4 is connected to the pin BAT10 of the LTC-68xx series chip.

3. A power supply circuit for collecting voltage of any battery cell as claimed in claim 1, characterized in that: The isolated power supply module is a 15V isolated power supply chip.

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