Fuel cell monomer voltage inspection circuit

Abstract

The utility model discloses a fuel cell monomer voltage inspection circuit. The circuit comprises a processor; the voltage acquisition unit comprises N voltage acquisition chips, and N is greater than or equal to 2; the system power supply is electrically connected with the processor; one end of each of the N isolated power supplies is electrically connected with the system power supply, and the other end of each of the N isolated power supplies is electrically connected with the N voltage acquisition chips in a one-to-one correspondence manner; one end of the communication conversion chip is electrically connected with the voltage acquisition unit, and the other end of the communication conversion chip is electrically connected with the processor. The device is high in integration level, is simple in hardware structure, and improves the precision and speed of the voltage collection of the single fuel cell.

Description

Technical Field

[0001] The utility model belongs to the technical field of fuel cell measurement, and more specifically relates to a fuel cell monomer voltage patrol circuit. Background Art

[0002] A fuel cell stack is composed of dozens or even hundreds of cells connected in series. The performance of the entire series system depends on the worst performing single fuel cell, so the voltage of the single cell must be tested. The fuel cell single cell voltage inspection system needs to perform real-time and accurate voltage detection and transmit the data to the host computer and the vehicle controller.

[0003] The traditional fuel cell detection method is the photorelay isolation method, which mainly uses a decoder and a photo-isolated relay array to select the single-chip voltage one by one, and then uses a differential amplifier to collect the voltage. When there are a large number of fuel cells in series, in order to avoid the impact of excessive cumulative potential, the single-chip voltage of the fuel cell needs to be measured in groups to form multiple detection units, each of which needs to include a signal transceiver and an MCU processor. Then, in order to detect negative pressure, a precise potential boost unit needs to be added to convert the negative pressure into a positive pressure that can be detected by the A / D converter.

[0004] This solution composed of discrete devices has a complex hardware structure and the detection accuracy is not high enough. At the same time, since it takes time for the photorelay to open and close, it takes a long time to inspect once when there are many battery stacks in series, and the collection rate is not fast enough. Utility Model Content

[0005] In view of at least one defect or improvement need of the prior art, the utility model provides a fuel cell cell voltage inspection circuit with high device integration and simple hardware structure, which is very suitable for the accuracy and rate of fuel cell cell voltage acquisition.

[0006] To achieve the above purpose, the utility model provides a fuel cell monomer voltage inspection circuit, comprising:

[0007] processor;

[0008] A voltage acquisition unit, wherein the voltage acquisition unit includes N voltage acquisition chips, where N is greater than or equal to 2;

[0009] a system power supply, the system power supply being electrically connected to the processor;

[0010] N isolated power supplies, one end of each of the N isolated power supplies being electrically connected to the system power supply, and the other end of each of the N isolated power supplies being electrically connected to the N voltage acquisition chips in a one-to-one correspondence;

[0011] A communication conversion chip, one end of which is electrically connected to the voltage acquisition unit, and the other end of which is electrically connected to the processor.

[0012] Furthermore, the N voltage acquisition chips are connected in a daisy chain manner, and the first voltage acquisition chip is also electrically connected to the communication conversion chip.

[0013] Furthermore, two adjacent voltage acquisition chips are connected via an isoSPI communication circuit.

[0014] Furthermore, the fuel cell monomer voltage inspection circuit also includes a communication module and a controller, one end of the communication module is electrically connected to the processor, and the other end of the communication module is electrically connected to the controller.

[0015] Furthermore, the communication module is a CAN communication module.

[0016] Furthermore, the controller is a host computer or a vehicle-mounted controller.

[0017] Furthermore, the voltage acquisition chip is an LTC6806 chip.

[0018] Furthermore, the communication conversion chip is an LTC6820 chip.

[0019] Further, the isolated power supply includes a power conversion module U1, a first inductor L1, a first resistor R1, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4, the power input pin Vin of the power conversion module is electrically connected to one end of the first inductor, the other end of the first inductor is electrically connected to the system power supply VCC, the first capacitor and the second capacitor are connected in parallel, the other end of the first inductor is also electrically connected to one end of the first capacitor and the second capacitor, the other ends of the first capacitor and the second capacitor are grounded, the positive voltage output end +V0 of the power conversion module is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to the corresponding voltage acquisition chip, the third capacitor and the fourth capacitor are connected in parallel, the positive voltage output end of the power conversion module is also electrically connected to one end of the first capacitor and the second capacitor, and the other ends of the first capacitor and the second capacitor are grounded.

[0020] Further, the isoSPI communication circuit includes a center-tapped transformer, a first voltage-dividing resistor R9, a second voltage-dividing resistor R11, a third voltage-dividing resistor R10, a fourth voltage-dividing resistor R12, a fifth capacitor C8, a sixth capacitor C9, a seventh capacitor C10 and an eighth capacitor C11, one end of the first voltage-dividing resistor is electrically connected to an input terminal 1 of the primary side of the center-tapped transformer, one end of the first voltage-dividing resistor is also electrically connected to one end CA_IPB of an isoSPI communication interface of a voltage acquisition chip, the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is electrically connected to another input terminal 3 of the primary side of the center-tapped transformer, the other end of the second voltage-dividing resistor is also electrically connected to the other end CA_IMB of the isoSPI communication interface of the voltage acquisition chip, the center tap 2 of the primary side of the center-tapped transformer is electrically connected to one end of the sixth capacitor, the other end of the sixth capacitor is grounded, and the fifth capacitor is electrically connected to one end of the isoSPI communication interface of the voltage acquisition chip. One end is electrically connected to the common section of the first voltage-dividing resistor and the second voltage-dividing resistor, the other end of the fifth capacitor is grounded, one end of the third voltage-dividing resistor is electrically connected to an output end 6 on the secondary side of the center-tapped transformer, one end of the third voltage-dividing resistor is also electrically connected to one end CB_IPA of the isoSPI communication interface of another voltage acquisition chip, the other end of the third voltage-dividing resistor is electrically connected to one end of the fourth voltage-dividing resistor, the other end of the fourth voltage-dividing resistor is electrically connected to the other end CB_IMA of the isoSPI communication interface of the other voltage acquisition chip, one end of the eighth capacitor is electrically connected to the common end of the third voltage-dividing resistor and the fourth voltage-dividing resistor, the center tap 5 on the secondary side of the center-tapped transformer is electrically connected to one end of the seventh capacitor, the other output end 4 on the secondary side of the center-tapped transformer is electrically connected to the other end of the isoSPI communication interface of the other voltage acquisition chip, and the other end of the seventh capacitor and the other end of the eighth capacitor are grounded.

[0021] In general, compared with the prior art, the present invention has the following advantages:

[0022] (1) This fuel cell single cell voltage inspection circuit uses an integrated voltage acquisition chip, which solves the problem of complex hardware structure and low reliability of the traditional discrete solution. At the same time, it saves space on the circuit board and the product volume can be smaller. In addition, an isolated power supply is used to power each voltage acquisition unit to avoid the problem of excessive accumulated potential.

[0023] (2) According to the test, it takes 10.3 ms for a voltage acquisition unit in the fuel cell single cell voltage inspection circuit to complete the inspection, which has a high sampling rate and good real-time performance.

[0024] (3) The single-channel detection range of the voltage acquisition chip LTC6806 used in the fuel cell single-cell voltage inspection circuit is -5 to 5V, and there is no need to add a potential boost unit to detect negative voltage.

[0025] (4) The accuracy of single-chip voltage acquisition of the fuel cell single-cell voltage inspection circuit is within ±15mV, and the sampling accuracy is good.

[0026] (5) The voltage acquisition chips in the fuel cell single cell voltage inspection circuit use two-wire isolated SPI communication, which has strong anti-interference performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a circuit diagram of a fuel cell monomer voltage inspection circuit according to an embodiment of the utility model;

[0028] Figure 2 It is a circuit schematic diagram of an isolated power supply of an embodiment of the utility model;

[0029] Figure 3 It is a schematic diagram of an isoSPI communication circuit between two adjacent voltage acquisition chips in an embodiment of the utility model;

[0030] Figure 4 It is a schematic diagram between the voltage acquisition chip and the communication conversion chip of an embodiment of the utility model. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0032] like Figure 1 As shown, a fuel cell monomer voltage inspection circuit of the present embodiment includes: a processor; a voltage acquisition unit, the voltage acquisition unit includes N voltage acquisition chips, N ≥ 2; a system power supply, the system power supply is electrically connected to the processor; N isolated power supplies, one end of the N isolated power supplies are electrically connected to the system power supply respectively, and the other end of the N isolated power supplies are electrically connected to the N voltage acquisition chips in a one-to-one correspondence; a communication conversion chip, one end of the communication conversion chip is electrically connected to the voltage acquisition unit, and the other end of the communication conversion chip is electrically connected to the processor.

[0033] The processor may specifically be a MCU microprocessor.

[0034] The number of voltage acquisition chips in the voltage acquisition unit can be determined according to the number of strings of the fuel cell stack.

[0035] The system power module processes the external input power, converts it into system power to power the processor, and then converts the system power into isolated power to power each voltage acquisition unit. Different voltage acquisition units use different isolated power supplies and do not share a common ground, thus avoiding the problem of excessive accumulated potential.

[0036] Furthermore, the N voltage acquisition chips are connected in a daisy chain manner, and the first voltage acquisition chip is also electrically connected to the communication conversion chip. Assuming there are 4 voltage acquisition chips, respectively denoted as A, B, C, and D, the daisy chain means that voltage acquisition chip A is electrically connected to voltage acquisition chip B, voltage acquisition chip B is electrically connected to voltage acquisition chip C, voltage acquisition chip C is electrically connected to voltage acquisition chip D, and voltage acquisition chip A is not connected to voltage acquisition chip D. In this connection method, a mesh topology structure will not be formed, and only adjacent devices can communicate directly. For example, voltage acquisition chip A cannot communicate directly with voltage acquisition chip C, and they must be transferred through voltage acquisition chip B. Voltage acquisition chip A is also electrically connected to the communication conversion chip.

[0037] Furthermore, two adjacent voltage acquisition chips are connected via an isoSPI communication circuit, that is, bidirectional isolated SPI communication is adopted. The first voltage acquisition chip uses a communication conversion chip to convert the isolated SPI into a normal SPI so as to communicate with the processor.

[0038] Furthermore, the fuel cell single cell voltage inspection circuit further includes a communication module and a controller, one end of the communication module is electrically connected to the processor, and the other end of the communication module is electrically connected to the controller. The processor transmits data to the controller through the communication module.

[0039] Furthermore, the communication module is a CAN communication module.

[0040] Furthermore, the controller is a host computer or a vehicle-mounted controller.

[0041] Furthermore, the voltage acquisition chip is an LTC6806 chip, each LTC6806 can collect voltages of 36 strings of cells at most, and bidirectional isolated SPI communication is adopted between each voltage acquisition chip LTC6806.

[0042] Furthermore, the communication conversion chip is an LTC6820 chip. The LTC6820 chip converts the isolated SPI into a normal SPI so as to communicate with the processor.

[0043] like Figure 2As shown, further, the isolated power supply includes a power conversion module U1, a first inductor L1, a first resistor R1, a first capacitor C1, a second capacitor C2, a third capacitor C3 and a fourth capacitor C4, the power input pin Vin of the power conversion module is electrically connected to one end of the first inductor, the other end of the first inductor is electrically connected to the system power supply VCC, the first capacitor and the second capacitor are connected in parallel, the other end of the first inductor is also electrically connected to one end of the first capacitor and the second capacitor, the other end of the first capacitor and the second capacitor is grounded, and the positive voltage output terminal +V O The first resistor is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to the corresponding voltage acquisition chip, the third capacitor and the fourth capacitor are connected in parallel, the positive voltage output end of the power conversion module is also electrically connected to one end of the first capacitor and the second capacitor, and the other end of the first capacitor and the second capacitor is grounded.

[0044] The rated input of the power conversion module U1 can be set to 4.5~5.5V, and the rated output can be set to 5V. It converts the system 5V power supply into an isolated 5V power supply. The inductor L1 is connected in series with the input of the power conversion module to isolate the mutual influence of the fluctuations of the front and rear circuits. For fuel cell stacks with a large number of series connections, multiple voltage acquisition units are used for measurement, and the units are cascaded in a daisy chain manner. Each voltage acquisition unit is equipped with an isolated power supply circuit. Since the isolated power supply and the system power supply do not share a common ground, the acquisition unit will not be affected by the high common mode potential.

[0045] The configuration of the voltage acquisition chip LTC6806 is described in detail below. The voltage acquisition circuit of the discrete solution is basically composed of an optocoupler, a decoder, an amplifier, a microcontroller, etc. The integrated solution integrates all of these into the chip, and the voltage acquisition unit is composed of the LTC6806 chip and its configuration circuit. C0~C36 of the LTC6806 chip are the 36 battery voltages to be measured. The DCMD pin is used to configure the cascade mode of the voltage acquisition unit. In this embodiment, it is connected to V+ for daisy chain connection. The ISOMD pin is used to configure whether the communication mode between the voltage acquisition units is four-wire SPI or two-wire isoSPI. In this embodiment, it is connected to V+, and the two-wire isoSPI is used, which has stronger anti-interference ability. After the ISOMD pin is configured, the pins IPA and IMA are used as the communication interface with the upper level, and the pins IPB and IMB are used as the communication interface with the next level. The IPA and IMA of the first voltage acquisition unit communicate with the MCU through the communication conversion chip LTC6820, and the IPB and IMB of the last voltage acquisition unit are idle. The IBIAS pin is connected to ground through a resistor to configure the output current of the isoSPI interface. The larger the output current, the stronger the anti-interference ability, but the greater the power consumption. Because the IBIAS pin voltage is fixed at 2V, the output current of the isoSPI interface is 20 times the current of the IBIAS pin, so two external 1k resistors are connected to configure the current to 20mA. The ICMP pin is used to configure the voltage threshold of the isoSPI receiver comparator. The comparator threshold is set to half the voltage on the ICMP pin. Here, the voltage threshold is configured to 0.5V. Other methods can also be used to configure the power supply and ground.

[0046] like Figure 3As shown, further, the isoSPI communication circuit includes a center-tapped transformer, a first voltage-dividing resistor R9, a second voltage-dividing resistor R11, a third voltage-dividing resistor R10, a fourth voltage-dividing resistor R12, a fifth capacitor C8, a sixth capacitor C9, a seventh capacitor C10 and an eighth capacitor C11, one end of the first voltage-dividing resistor is electrically connected to an input terminal 1 of the primary side of the center-tapped transformer, one end of the first voltage-dividing resistor is also electrically connected to one end CA_IPB of an isoSPI communication interface of a voltage acquisition chip, the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is electrically connected to another input terminal 3 of the primary side of the center-tapped transformer, the other end of the second voltage-dividing resistor is also electrically connected to the other end CA_IMB of the isoSPI communication interface of the voltage acquisition chip, the center tap 2 of the primary side of the center-tapped transformer is electrically connected to one end of the sixth capacitor, the other end of the sixth capacitor is grounded, and the fifth capacitor One end of the fifth capacitor is electrically connected to the common segment of the first voltage-dividing resistor and the second voltage-dividing resistor, the other end of the fifth capacitor is grounded, one end of the third voltage-dividing resistor is electrically connected to an output terminal 6 on the secondary side of the center-tapped transformer, one end of the third voltage-dividing resistor is also electrically connected to one end CB_IPA of the isoSPI communication interface of another voltage acquisition chip, the other end of the third voltage-dividing resistor is electrically connected to one end of the fourth voltage-dividing resistor, the other end of the fourth voltage-dividing resistor is electrically connected to the other end CB_IMA of the isoSPI communication interface of the other voltage acquisition chip, one end of the eighth capacitor is electrically connected to the common end of the third voltage-dividing resistor and the fourth voltage-dividing resistor, the center tap 5 on the secondary side of the center-tapped transformer is electrically connected to one end of the seventh capacitor, the other output terminal 4 on the secondary side of the center-tapped transformer is electrically connected to the other end of the isoSPI communication interface of the other voltage acquisition chip, and the other end of the seventh capacitor and the other end of the eighth capacitor are grounded.

[0047] The connection between the first voltage acquisition chip LTC6806 and the communication conversion chip is as follows Figure 4 shown.

[0048] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fuel cell single cell voltage inspection circuit, characterized in that: include: processor; A voltage acquisition unit, wherein the voltage acquisition unit includes N voltage acquisition chips, where N is greater than or equal to 2; a system power supply, the system power supply being electrically connected to the processor; N isolated power supplies, one end of each of the N isolated power supplies being electrically connected to the system power supply, and the other end of each of the N isolated power supplies being electrically connected to the N voltage acquisition chips in a one-to-one correspondence; A communication conversion chip, one end of which is electrically connected to the voltage acquisition unit, and the other end of which is electrically connected to the processor.

2. The fuel cell monomer voltage inspection circuit according to claim 1, characterized in that: The N voltage acquisition chips are connected in a daisy chain manner, and the first voltage acquisition chip is also electrically connected to the communication conversion chip.

3. The fuel cell monomer voltage inspection circuit according to claim 2, characterized in that: Two adjacent voltage acquisition chips are connected via an isoSPI communication circuit.

4. The fuel cell monomer voltage inspection circuit according to claim 1, characterized in that: It also includes a communication module and a controller, one end of the communication module is electrically connected to the processor, and the other end of the communication module is electrically connected to the controller.

5. The fuel cell monomer voltage inspection circuit according to claim 4, characterized in that: The communication module is a CAN communication module.

6. The fuel cell monomer voltage inspection circuit according to claim 4, characterized in that: The controller is a host computer or a vehicle-mounted controller.

7. The fuel cell monomer voltage inspection circuit according to claim 1, characterized in that: The voltage acquisition chip is an LTC6806 chip.

8. The fuel cell monomer voltage inspection circuit according to claim 1, characterized in that: The communication conversion chip is an LTC6820 chip.

9. The fuel cell monomer voltage inspection circuit according to claim 1, characterized in that: The isolated power supply includes a power conversion module, a first inductor, a first resistor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor. The power input pin of the power conversion module is electrically connected to one end of the first inductor, the other end of the first inductor is electrically connected to the system power supply, the first capacitor and the second capacitor are connected in parallel, the other end of the first inductor is also electrically connected to one end of the first capacitor and the second capacitor, the other ends of the first capacitor and the second capacitor are grounded, the positive voltage output end of the power conversion module is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to the corresponding voltage acquisition chip, the third capacitor and the fourth capacitor are connected in parallel, the positive voltage output end of the power conversion module is also electrically connected to one end of the first capacitor and the second capacitor, and the other ends of the first capacitor and the second capacitor are grounded.

10. The fuel cell monomer voltage inspection circuit according to claim 3, characterized in that: The isoSPI communication circuit includes a center-tapped transformer, a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor and an eighth capacitor, one end of the first voltage-dividing resistor is electrically connected to an input end of the primary side of the center-tapped transformer, one end of the first voltage-dividing resistor is also electrically connected to one end of an isoSPI communication interface of a voltage acquisition chip, the other end of the first voltage-dividing resistor is electrically connected to one end of the second voltage-dividing resistor, the other end of the second voltage-dividing resistor is electrically connected to the other input end of the primary side of the center-tapped transformer, the other end of the second voltage-dividing resistor is also electrically connected to the other end of the isoSPI communication interface of the voltage acquisition chip, the center tap of the primary side of the center-tapped transformer is electrically connected to one end of the sixth capacitor, the other end of the sixth capacitor is grounded, one end of the fifth capacitor is electrically connected to the first voltage-dividing resistor, The common section of the second voltage-dividing resistor is electrically connected to the center tap transformer, the other end of the fifth capacitor is grounded, one end of the third voltage-dividing resistor is electrically connected to an output end of the secondary side of the center tap transformer, one end of the third voltage-dividing resistor is also electrically connected to one end of the isoSPI communication interface of another voltage acquisition chip, the other end of the third voltage-dividing resistor is electrically connected to one end of the fourth voltage-dividing resistor, the other end of the fourth voltage-dividing resistor is electrically connected to the other end of the isoSPI communication interface of the other voltage acquisition chip, one end of the eighth capacitor is electrically connected to the common end of the third voltage-dividing resistor and the fourth voltage-dividing resistor, the center tap of the secondary side of the center tap transformer is electrically connected to one end of the seventh capacitor, the other output end of the secondary side of the center tap transformer is electrically connected to the other end of the isoSPI communication interface of the other voltage acquisition chip, and the other end of the seventh capacitor and the other end of the eighth capacitor are grounded.

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