CN1746695A - A single-chip voltage monitoring device for vehicle fuel cells - Google Patents

Abstract

A device for monitoring single plate voltage of vehicle fuel cell is featured as connecting input end of optical couple gating communication circuit to each single plate of fuel cell in sequence, connecting output end to isolation circuit input end, inputting signal to monolithic computer through absolute value circuit after isolation treatment, controlling four I / O pin signals by said computer and using hardware interlocking circuit to ensure uniqueness of gating channel, carrying out communication with external main controller by monolithic computer through CAN communication circuit.

Description

A single-chip voltage monitoring device for vehicle fuel cells

technical field

The invention belongs to a fuel cell voltage monitoring device, in particular to a vehicle fuel cell monolithic voltage monitoring device.

Background technique

Fuel cell monolithic voltage is one of the important indicator parameters of fuel cell performance. By measuring its value, the working state of the fuel cell stack can be monitored to achieve the purpose of protecting the fuel cell.

The operating range of fuel cell single chip voltage is generally less than 1V, and it can be slightly higher than 1V at no-load. As a single-chip voltage monitoring device for vehicle fuel cells, the following technical requirements need to be met:

(1) Fast measurement speed: Due to power requirements, fuel cells for vehicles are generally composed of hundreds or thousands of monoliths. To ensure real-time measurement, the measurement speed of each monolith should be as fast as possible, generally less than 1ms , to complete all single-chip measurements in less than 1s.

(2) High measurement accuracy: Since the normal operating range of a single fuel cell is 0-1V, the measurement accuracy should reach the order of 10mV.

(3) It has strong expansion ability and can communicate with the main controller conveniently.

(4) Strong anti-interference ability: Since the fuel cell stack is in a strong electric environment, the problem of electromagnetic interference is serious; in addition, in order to adapt to the working conditions of vehicles, it also needs to have better performance such as shock resistance and adaptability to temperature changes.

(5) Moderate cost.

The primary difficulty in measuring the single-chip voltage of fuel cells used in vehicles is the problem of potential accumulation, especially as the number of single-chip fuel cells continues to increase, this problem becomes more obvious, which poses higher demands on the withstand voltage value and safety of the device. requirements.

At present, in order to solve the potential accumulation, commonly used monolithic voltage monitoring solutions include: resistor divider, resistor-diode divider, optocoupler isolation relay gating, linear isolation differential op amp and other methods. However, these methods all have certain deficiencies. For example, when the resistance voltage division method measures a large number of single chips, the error is too large; the method of applying a linear isolated differential operational amplifier requires that each single cell be equipped with an isolated differential operational amplifier, and the system cost High, bulky, complicated wiring. Now the method of photoelectric isolation relay is widely used. It directly measures each single chip through the method of optocoupler gating. It has high precision, but its safety is not perfect, especially the stack measurement reference ground and The isolation problem between the power supply and the ground of the measurement circuit needs to be improved. If this problem is not solved properly, it is easy to cause the circuit of the single-chip microcomputer to be burned.

Contents of the invention

The object of the present invention is to provide a vehicle fuel cell monolithic voltage monitoring device, which can monitor the voltage of each monolithic fuel cell in the vehicle, so as to provide control reference information for the main controller of the fuel cell.

In order to solve the above problems, the technical solution adopted in the present invention is:

The vehicle fuel cell monolithic voltage monitoring device includes five parts: optocoupler gating circuit, isolation circuit, absolute value circuit, hardware interlock circuit, single chip microcomputer and CAN communication circuit.

The optocoupler gating circuit 2 is used to gate the potentials at both ends of each monolithic battery, so as to realize the direct measurement of the voltage of a single monolithic battery and solve the problem of potential accumulation. It uses 64 dual-channel optocoupler isolation relays as gating elements, and a total of 124 single-chip voltages can be selected.

The isolation circuit 3 is used for isolation between the fuel cell signal gating circuit and the signal processing circuit of the single-chip microcomputer, thereby preventing the electrical environment of the fuel cell from interfering with the single-chip microcomputer circuit, and improving electromagnetic compatibility. It uses an isolated operational amplifier as its core component.

The absolute value circuit 4 is used to convert the positive and negative alternating signals generated by the gating into a positive signal acceptable to the single-chip microcomputer, and filter out the negative signal through a non-inverting follower powered by a single-ended positive voltage.

The hardware interlock circuit 5 is used to control the decoder chip matched with the optocoupler gating circuit to prevent the danger of overvoltage caused by the optocoupler gating of non-adjacent channels and improve the fault tolerance of the system. It is realized by a set of NAND gate logic circuits.

The single-chip microcomputer and CAN communication circuit 6 are used for AD conversion and data transmission of single-chip voltage signals, and its CAN communication adopts the latest TTCAN protocol, which has greatly improved communication rhythm and reliability.

The connection mode of the whole device is as follows: the input end of the optocoupler gating circuit 2 is respectively connected to each single chip 1 of the fuel cell in sequence, and its output end is connected to the input end of the isolation circuit 3, and the isolation circuit 3 isolates the signal and then passes through The absolute value circuit 4 inputs the single-chip microcomputer 6 through two AI pins. In order to improve the hardware fault tolerance, the single-chip microcomputer 6 controls the four-way I/O pin signals, and the hardware interlock circuit 5 ensures the uniqueness of the strobe channel. Communicate with the external main controller 7 through the CAN communication circuit 6 .

The beneficial effects of the present invention are: through the isolation circuit, the isolation problem between the electrical system of the measurement object and the single-chip electromechanical system in the existing scheme is effectively solved, and the electromagnetic compatibility of the circuit is improved; The cost problem of the bipolar AD conversion chip; through the hardware interlock circuit, the overvoltage hazard problem of non-adjacent channel gating caused by software and electromagnetic interference in the existing optocoupler gating scheme is solved; the monitoring device can measure 124 single-chip voltage values, using multiple devices to form a monitoring system, and through the CAN network using the TTCAN protocol for orderly communication between each device and the main controller, can realize all fuel cell stacks with a large number of single chips Monolithic voltage measurement.

Compared with the prior art, the present invention has high safety, small size and moderate cost; high measurement accuracy (the single-chip measurement error is on the order of 10mV), fast measurement speed (single-chip measurement takes less than 1ms); strong communication capability and easy expansion application, which fully meets the needs of single-chip voltage monitoring of vehicle-mounted fuel cell stacks. The invention is also applicable to the monitoring of the single-chip voltage of non-mobile fuel cell stacks, and the voltage monitoring of similar battery systems composed of many single-chips.

Description of drawings

Figure 1 is a structural block diagram of a fuel cell monolithic voltage monitoring device, in which, 1-fuel cell monolithic, 2-optocoupler gating circuit, 3-isolation circuit, 4-absolute value circuit, 5-hardware interlock circuit, 6-single-chip microcomputer And CAN communication circuit, 7-fuel cell main controller, 8-single chip microcomputer I/O port, 9-decoder enabling port.

Figure 2 is a schematic diagram of the optocoupler gating circuit.

Figure 3 is a schematic diagram of the isolation circuit.

Fig. 4 is a schematic diagram of an absolute value circuit.

Fig. 5 is a schematic diagram of a hardware interlock circuit.

Figure 6 is the TTCAN communication protocol.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Figure 1 is a structural block diagram of a fuel cell monolithic voltage monitoring device, where 1 is a fuel cell monolith, 2 is an optocoupler gating circuit, 3 is an isolation circuit, 4 is an absolute value circuit, 5 is a hardware interlock circuit, 6 7 is the main controller of the fuel cell, 8 is the I/O port of the single-chip microcomputer, and 9 is the enabling port of the decoder. Shown in the dotted line box is the structure of the device, including optocoupler gating circuit 2, isolation circuit 3, absolute value circuit 4, hardware interlock circuit 5, single-chip microcomputer and CAN communication circuit 6. The input terminals of the optocoupler gating circuit 2 are sequentially connected to each single chip 1 of the fuel cell, and the output terminals thereof are connected to the input terminals of the isolation circuit 3, and the conduction of the optocoupler is controlled by the single-chip microcomputer through a decoder; the isolation circuit 3 The signal is isolated and processed so that no direct physical connection occurs between the front and back signals and the ground; the absolute value circuit 4 converts the positive and negative alternating signals of the isolated rear stage into absolute values, and inputs the single-chip microcomputer 6 through two AI pins; in order to improve Hardware fault tolerance, the single-chip microcomputer 6 controls the four-way I/O pin 8 signal, and the hardware interlock circuit 5 ensures the uniqueness of the gating channel; the single-chip microcomputer 6 converts and processes the signal and uses the TTCAN protocol through the CAN communication circuit 6 Communicate with the main controller 7 of the fuel cell.

)同时与硬件互锁电路的四个输出端之一相连；光电隔离继电器控制端的一极与译码器的输出端相连，并且两者的引脚一一对应，另一级与电阻RVA相连，该电阻与+5V电源相连；光电隔离继电器的被控制端的输入引脚与燃料电池单片电势点(如V0，V1等)相连，输出引脚交替地连接到COMA、COMB输出总线上。Figure 2 shows a schematic diagram of the optocoupler gating circuit. The optocoupler gating circuit uses 64 pieces of AQW214 photoelectric isolation relays, which are divided into 4 identical optocoupler arrays, and each array is gated by two 4-to-16 decoders 74HC154; each group of two decoders has 4 A chip selection input terminal is connected with the P3 port of the single-chip microcomputer, the output terminal is connected with the control terminal of the photoelectric isolation relay, and the enabling terminals of the two decoders (

) is connected to one of the four output terminals of the hardware interlock circuit at the same time; one pole of the control terminal of the photoelectric isolation relay is connected to the output terminal of the decoder, and the pins of the two correspond one by one, and the other level is connected to the resistor RVA. The resistor is connected to the +5V power supply; the input pin of the controlled end of the photoelectric isolation relay is connected to the fuel cell monolithic potential point (such as V0, V1, etc.), and the output pin is alternately connected to the COMA, COMB output bus.

The monitoring device uses a total of 64 pieces of AQW214 photoelectric isolation relays, which are divided into 4 identical optocoupler arrays. Each array is gated by two 4-to-16 decoders 74HC154. The entire device can monitor 124 single-chip voltage values. . The four chip-select input signals (A, B, C, D) of each group of two decoders are provided by the P3 port of the single-chip microcomputer, and the corresponding output terminals of the two decoders (such as YE0 and YF0) are respectively connected to the same optical Coupled to one pin of the control end of the two channels of AQW214 (pins 2 and 4 of AQW214), pins 1 and 3 of AQW214 are pulled up to 5V through pull-up resistors, and pins 6 and 8 of the controlled end of the optocoupler are pulled up to 5V. The pins are respectively connected to the potential points of the adjacent single chip of the fuel cell. Under the control of the single chip computer software, the two decoders respectively control the conduction of two adjacent channels in the optocoupler array, so as to realize the measurement of the voltage of a single single cell. The enable terminal of the decoder ( OE1, OE2) is controlled by a hardware interlock circuit, so that only one group of decoders works at the same time. Since the conduction resistance of the AQW214 photoelectric isolation relay is very small, and its subsequent stage is connected to an operational amplifier with infinite input resistance, the loss of the signal here can be ignored. All single-chip potential points V(2n) with even numbers are connected to the COMA line after they are turned on, and all single-chip potential points V(2n+1) with odd numbers are connected to the COMB line after they are turned on. Alternately, the potential difference between COMA and COMB will change positive and negative alternately, but its absolute value is equal to the voltage of the corresponding single-chip battery. In the subsequent processing, COMB is used as the reference ground for measurement.

Figure 3 shows a schematic diagram of the isolation circuit. The isolation circuit uses precision operational amplifier OP07(I), isolation operational amplifier AD202(II) and precision operational amplifier AD711(III), and they are connected in sequence. The positive input terminal (3) of the operational amplifier I is connected to the resistor IR1 and the capacitor IC1 respectively, the other end of the resistor IR1 is connected to the output bus COMA of the optocoupler gating circuit, and the negative input terminal (2) of the operational amplifier I is connected to the resistor IR2 The resistor IR2 is connected to the output bus COMB of the capacitor IC1 and the optocoupler gating circuit respectively, and the negative input terminal (2) of the operational amplifier I is also connected to its own output terminal (6) through the resistor IR3 to form a feedback; the operational amplifier I The output terminal (6) of the isolated operational amplifier II is connected to the positive input terminal (1), and the feedback terminal (38) of the isolated operational amplifier II is directly connected to its negative input terminal (3). Following the amplifier, the positive output terminal of the isolated operational amplifier II is connected to the resistor IR5, and the negative output terminal is directly grounded; while the resistor IR5 is grounded through the capacitor IC7, it is connected to the positive input terminal (3) of the operational amplifier III, and the operational amplifier III The negative input terminal of the negative direction is directly connected with its output terminal (6) to form a feedback, and its output terminal Outab is connected with the input terminal of the absolute value circuit. Operational amplifier I adopts ±7.5V double-terminal power supply (+VISO, -VISO). They are respectively connected to COMB through capacitors; the common ground terminal (2) of the isolated operational amplifier II is connected to COMB, and the common ground terminal (22) of the latter stage is connected to the circuit ground of the single-chip microcomputer. The operational amplifier is powered by +15V; the operational amplifier III adopts ± 15V double-terminal power supply, its positive and negative power supply terminals (7, 4) are connected to the circuit ground of the single-chip microcomputer through a capacitor at the same time; resistors IR2 and IR3 in this circuit adopt 0.1% precision resistors.

Since the measured reference ground COMB is a constantly changing floating value, its potential relative to the fuel cell ground may be as high as several hundred volts. If it is directly connected to the power supply ground of the single-chip microcomputer, it is likely to cause the circuit to be burned, and the safety hazard is very serious. , the two need to be isolated. This device adopts isolated operational amplifier AD202, which has many excellent characteristics: its interior has effectively isolated the signal and power supply of the front and rear stages; the maximum offset voltage (OffsetVoltage) of its K-level precision model is only ±5mV , the bias voltage of the J-level precision model is up to ±15mV (experiments show that its typical value can be controlled within ±10mV, which is almost the same as the K-level precision), and the gain error caused by the operational amplifier is basically maintained at a fixed value. , can be reduced by the method of calibration, so as to meet the accuracy requirements of single-chip acquisition; the op amp outputs a pair of ±7.5V power supply in its front stage, which is generated by the 15V power supply of the latter stage but isolated from it, and is used for Supply power to the chip in the front stage of the op amp without affecting the isolation effect. The specific circuit principle is: among the two signals after optocoupler gating, COMB is used as the reference ground, and COMA is used as the signal line; The operational amplifier circuit is doubled. The resistors IR2 and IR3 used in this non-directional operational amplifier are both 0.1% sticky resistors. The positive and negative power supply pins 7 and 4 of OP07 are respectively connected to the ±7.5V power supply ±7.5V output by the front stage of AD202 VISO is connected to COMB through a 1uF capacitor to maintain the stability of the power supply. The purpose of the amplification process is to relatively reduce the impact of the gain error of the isolated operational amplifier AD202 on the measurement accuracy; the filtered and amplified signal enters the AD202 The +Input pin and -Input pin are connected to the feedback pin IFeedback of AD202, and the Icommon pin is connected to COMB, so that the front stage inside the AD202 constitutes a follower in the same direction, and the Ocommon pin of the rear stage of the AD202 is connected to the microcontroller circuit The +15V power supply is provided by the single-chip circuit power supply (5V) through DCDC boost. Among the two outputs of AD202, OutputL is directly connected to the single-chip circuit ground, and OutputH is used as a signal line. After the signal passes through AD202, its signal and ground Both achieve effective isolation; the output signal of AD202 is output after an RC first-order filter and a non-inverting follower composed of a precision operational amplifier AD711. It is provided after boosting, and is connected to the circuit ground of the single-chip microcomputer through a 1uF capacitor respectively to keep the power supply stable. The input resistance of the circuit breaker is equivalent to infinite, while the output resistance is very small, so it can effectively enhance the ability of the circuit to carry the load.

Figure 4 shows the schematic diagram of the absolute value circuit. The absolute value circuit uses 2 precision operational amplifiers AD820 (I, III) and 1 precision operational amplifier OP177 (II), and they are divided into two circuits and connected in sequence. In the first way, the positive input terminal (3) of the operational amplifier I is connected with the output terminal Outab of the isolation circuit, and the negative input terminal (2) is directly connected with the output terminal (6) to form a feedback, and the output terminal (6) is connected with the output terminal (6). The AIN0.0 pin of the single chip microcomputer is connected; in the second way, the positive input terminal (3) of the operational amplifier II is grounded, and the negative input terminal (2) is connected to the output terminal Outab of the isolation circuit through the resistor IR7, while the negative input terminal (2) Connect to the output terminal (6) through the resistor IR8 to form a feedback, the output terminal (6) of the operational amplifier II is connected to the positive input terminal (3) of the operational amplifier III; the negative input terminal (2) of the operational amplifier III ) is directly connected to its output terminal (6) to form a feedback, and its output terminal (6) is connected to the AIN0.1 pin of the single-chip microcomputer. Operational amplifiers I and III adopt +15V single-ended power supply, and their negative power supply terminal (4) is directly connected to the ground, and the positive power supply terminal (7) is connected to the single-chip circuit ground through capacitors IC9 and IC12 respectively; operational amplifier II adopts ±15V dual terminal power supply, its positive and negative power supply terminals (7, 4) are connected to the circuit ground of the single-chip microcomputer through electric capacity IC10, IC11 respectively; Resistor IR7, IR8 adopt the precision resistance of 0.1% in this circuit.

Since the optocoupler gating circuit generates positive and negative signals alternately, and the pins of the single-chip microcomputer cannot withstand excessive negative voltage, so the signal after gating and isolation needs to be absolute valued before it can be introduced into the single-chip microcomputer. It would be ideal to complete the above operations with only one circuit and one single-chip microcomputer pin, but some existing absolute value circuits generally have problems of insufficient precision and complicated structure. There is a lot of surplus, so the two pins of the single-chip microcomputer are used to separately process the positive and negative signals with a relatively simple circuit. The specific situation is: the first channel is introduced into the AIN0.0 pin of the single-chip microcomputer for the input of positive voltage signals. A single-ended positive voltage non-inverting follower composed of a precision operational amplifier AD820 is placed on the road. Its positive power supply pin is connected to +15V (provided by DCDC), and its negative power supply pin is connected to the circuit ground of the microcontroller. The positive voltage signal can pass through this follower, and the negative voltage signal will be saturated to close to 0 level; the second way is introduced into the AIN0.1 pin of the microcontroller for the input of the negative voltage signal, and a double-ended circuit composed of a precision op amp OP177 is first placed on the way The inverting follower for power supply, its positive and negative power supply pins are respectively connected to ±15V (provided by DCDC), the resistors IR7 and IR8 used are 0.1% precision resistors, and then connected to the same AD820 single-ended positive A voltage-powered non-inverting follower, so that the negative voltage signal is first inverted into a positive voltage signal, and then input to the pin of the microcontroller, and the positive voltage signal is inverted into a negative voltage signal and then saturated to 0 level by the non-inverting follower. Inside the microcontroller, the synchronization of AD conversion and channel gating is realized through software control.

FIG. 5 is a schematic diagram of a hardware interlock circuit. The hardware interlock circuit uses a 2-input 4-channel NAND gate chip 74LS00 (I) and two 4-input 2-channel NAND gate chips 74LS20 (II, III). The two input terminals (1, 2; 4, 5; 9, 10; 12, 13) of the 4 channels of the NAND gate I are connected to each other and then connected to the P1.0 ~ P1.3 pins of the single chip microcomputer. The output terminals (3, 6, 8, 11) are respectively connected to the input terminals of the NAND gate II and III; among the 4 input terminals of each channel of the NAND gate II and III, 3 pins are used to connect the NAND gate I Output, one pin is directly connected to one of the P1.0~P1.3 pins of the microcontroller, the connection combinations of the 4 channels are mutually exclusive, the outputs of the NAND gates II and III are connected to the decoder in the optocoupler gating circuit The enable terminal is connected.

When the optocoupler is gated, it must be ensured that only two adjacent channels are gated, otherwise there will be a large potential difference between ComA and ComB in the subsequent stage, especially when the two channels are in different optocoupler arrays , the voltage difference between the two can reach tens of volts, or even hundreds of volts, which will burn the entire monitoring circuit in an instant. Since the control of the optocoupler gating is realized by the software of the single-chip microcomputer, if the software is wrongly programmed or run incorrectly, it may cause the above consequences, so it needs to be protected from the hardware design. The principle of the hardware interlock circuit is to control the enable terminals of each group of decoders so that only one group of decoders is enabled at a time, so that the non-enabled decoders will not generate channels even if they have input signals. the strobe. The method to realize this function is to control a logic gate circuit through a single-chip microcomputer to generate a group of mutually exclusive logic control signals. A two-input NAND gate chip 74LS00 and two four-input NAND gate chips 74LS20 are used here. There are four two-input NAND gates in 74LS00, which are used to generate the corresponding NAND gates corresponding to the single-chip microcomputer inputs P1.0~P1.3. Logic signal P1.0N～P1.3N, there are two four-input NAND gates in 74LS20, and a total of four four-input NAND gates in two 74LS20s respectively generate control signals (PR1-PR4) corresponding to the enable terminals of the decoder). The logic truth table is as follows (P1.0~P1.3 are the pin signals of the single chip microcomputer, PR1~PR4 are the enable terminal signals of the four sets of decoders):

MCU output   Decoder enable terminal signal P1.3 P1.2 P1.1 P1.0 PR4 PR3 PR2 PR1 L L L H H H H L L L H L H H L H L H L L H L H H H L L L L H H H Other situations H H H H

Figure 6 is the TTCAN communication protocol. The monitoring node and the main control node are connected through the CAN network and communicate with the TTCAN protocol. When there are multiple nodes in the CAN network, the rational design of the structure of the time matrix in the TTCAN protocol is related to the security of the communication. The design analysis is as follows: Since the task of each node is exactly the same and has a very strict periodicity, the system matrix of the TTCAN network can only consist of one basic cycle; since each node needs to monitor 124 single-chip voltage signals, The acquisition time of each signal is less than 1ms (1ms here), and the time required for a single node to complete a round of acquisition is 124ms. In order to ensure that all new data is sent each time, the communication cycle of a single node should be more than 124ms , that is, the period of the basic cycle should be above 124ms; in the basic cycle, the size of the exclusive time window of each node depends on the time it takes to complete 124 single-chip signal transmissions. Theoretical analysis and experiments show that the time is about 16ms, which is To ensure a certain margin, the design is 20ms. As shown in Figure 7, taking the TTCAN network with 10 nodes as an example, the basic cycle is composed of 10 exclusive time windows, and the reference message of the master control node is used as the time start mark. Require.

The single-chip microcomputer here adopts the 100-pin C8051F040 single-chip microcomputer of American SiliconLab. This is a highly integrated single-chip microcomputer, which represents the development trend of 8-bit single-chip system on chip SoC (System on Chip). Its main functions include: 13-way 12-bit AD conversion, 8 8-bit wide port I/O, 5 general-purpose counters/timers, Bosch CAN controller (CAN 2.0B), 64KB FLASH/4KB RAM. The CAN communication circuit is realized by the integrated Bosch CAN controller module inside the microcontroller, which is connected to the CAN communication circuit through CANRX and CANTX pins. The CAN transceiver is 82C250. In order to ensure good electromagnetic compatibility, the signal and power of the communication circuit are Corresponding isolation measures are taken. The signal isolation is realized by 6N137 optocoupler with appropriate resistors and capacitors. The power isolation is realized by DCP010505 DC-DC.

Claims (9)

1. A vehicle fuel cell monolithic voltage monitoring device, characterized in that the monitoring device comprises 5 parts: an optocoupler gating circuit, an isolation circuit, an absolute value circuit, a hardware interlock circuit, a single-chip microcomputer and a CAN communication circuit; The optocoupler gating circuit is used to gate the potentials at both ends of each monolithic battery separately, realize the direct measurement of the voltage of a single monolithic battery, and solve the problem of potential accumulation. 64 dual-channel optocoupler isolation relays are used as gating elements. A total of 124 single-chip voltages are selected; The isolation circuit is used for isolation between the fuel cell signal gating circuit and the single-chip microcomputer signal processing circuit, to prevent the electrical environment of the fuel cell from interfering with the single-chip microcomputer circuit, and to improve electromagnetic compatibility. It uses an isolated operational amplifier as its core component; The absolute value circuit is used to convert the positive and negative alternating signals generated by the gating into a positive signal that the microcontroller can accept, and filter out the negative signal through a non-inverting follower powered by a single-ended positive voltage; The hardware interlock circuit is used to control the decoder chip matched with the optocoupler gate circuit to prevent the overvoltage danger caused by the optocoupler gate of non-adjacent channels and improve the fault tolerance of the system; Realization of gate logic circuit; Single-chip microcomputer and CAN communication circuit are used for AD conversion and data transmission of single-chip voltage signal and communication between circuits; The input terminals of the optocoupler gating circuit are respectively connected to the single chips of the fuel cell in sequence, and the output terminals are connected to the input terminals of the isolation circuit. , the single-chip microcomputer controls the four-way I/O pin signals, and the hardware interlock circuit ensures the uniqueness of the gating channel, and the single-chip microcomputer communicates with the external main controller through the CAN communication circuit. 2. A single-chip voltage monitoring device for a vehicle fuel cell according to claim 1, wherein the optocoupler gating circuit uses 64 pieces of photoelectric isolation relays, which are divided into 4 identical optocoupler arrays, each The array is gated by two 4-to-16 decoders; the 4 chip-select input terminals of each group of two decoders are connected to the P3 port of the single-chip microcomputer, and the output terminals are connected to the control terminal of the photoelectric isolation relay. Encoder enable terminal At the same time, it is connected to one of the four output terminals of the hardware interlock circuit; one pole of the control terminal of the photoelectric isolation relay is connected to the output terminal of the decoder, and the pins of the two correspond one by one, and the other level is connected to the resistor RVA. The resistor is connected to the +5V power supply; the input pin of the controlled end of the photoelectric isolation relay is connected to the potential point of the single-chip fuel cell, and the output pin is alternately connected to the COMA and COMB output buses. 3. The monolithic voltage monitoring device for a vehicle fuel cell according to claim 1, wherein the isolation circuit uses a precision operational amplifier OP07 (I), an isolation operational amplifier AD202 (II) and a precision operational amplifier AD711 (III), and sequentially connected; the positive input terminal (3) of the precision operational amplifier OP07 (I) is connected with the resistance IR1 and the capacitor IC1 respectively, and the other end of the resistance IR1 is connected with the output bus COMA of the optocoupler gating circuit, and the precision calculation The negative input terminal (2) of the amplifier OP07 (I) is connected with the resistor IR2, and the resistor IR2 is connected with the output bus COMB of the capacitor IC1 and the optocoupler gating circuit respectively, and the negative input terminal (2) of the precision operational amplifier OP07 (I) is It is also connected to its own output terminal (6) through the resistor IR3 to form a feedback; the output terminal (6) of the precision operational amplifier OP07 (I) is connected to the positive input terminal (1) of the isolation operational amplifier AD202 (II) to isolate the operation The feedback terminal (38) of the amplifier AD202 (II) is directly connected to its negative input terminal (3), and the same direction follower amplifier is formed inside the isolation operational amplifier, and the positive output terminal of the isolation operational amplifier AD202 (II) is connected to the resistor IR5, The negative output terminal is directly grounded; while the resistor IR5 is grounded through the capacitor IC7, it is connected to the positive input terminal (3) of the precision operational amplifier AD711(III), and the negative input terminal of the precision operational amplifier AD711(III) is connected to its output terminal ( 6) Directly connected to form feedback, its output terminal Outab is connected to the input terminal of the absolute value circuit; the precision operational amplifier OP07 (I) adopts ± 7.5V double-terminal power supply (+VISO, -VISO), and the power supply is provided by the isolated operational amplifier AD202 (II) pre-stage output voltage terminals (36, 37) provide, precision operational amplifier OP07 (I) positive and negative power supply terminals (7, 4) are also connected to COMB respectively through capacitor; isolated operational amplifier AD202 (II) pre-stage common ground Terminal (2) is connected with COMB, and the common ground terminal (22) of the rear stage is connected with the circuit ground of the one-chip computer, and this operational amplifier is powered by +15V; Precision operational amplifier AD711 (III) adopts ± 15V double-terminal power supply, its positive and negative power supply terminal ( 7, 4) At the same time, it is connected to the circuit ground of the single-chip microcomputer through a capacitor. 4. The monolithic voltage monitoring device for a vehicle fuel cell according to claim 1, wherein the absolute value circuit uses two precision operational amplifiers AD820 (I, III) and one precision operational amplifier OP177 ( II), and be divided into two roads and connect in sequence; in the first road, the positive input terminal (3) of the precision operational amplifier AD820 (I) is connected with the output terminal Outab of the isolation circuit, and the negative input terminal (2) is connected with the output terminal ( 6) directly connected to form feedback, the output terminal (6) is connected to the AIN0.0 pin of the single chip microcomputer; in the second circuit, the positive input terminal (3) of the precision operational amplifier OP177 (II) is grounded, and the negative input terminal (2 ) is connected to the output terminal Outab of the isolation circuit through the resistor IR7, and the negative input terminal (2) is connected to the output terminal (6) through the resistor IR8 at the same time to form a feedback. The output terminal (6) of the precision operational amplifier OP177 (II) is connected to the precision The positive input terminal (3) of the operational amplifier AD820(III) is connected; the negative input terminal (2) of the precision operational amplifier AD820(III) is directly connected with its output terminal (6) to form a feedback, and its output terminal (6) is connected to The AIN0.1 pins of the single-chip microcomputer are connected; the precision operational amplifier AD820 (I, III) adopts +15V single-ended power supply, and its negative power supply terminal (4) is directly grounded, and the positive power supply terminal (7) is connected to the single-chip microcomputer through capacitors IC9 and IC12 respectively. The circuit ground is connected; the precision operational amplifier OP177 (II) adopts ±15V double-terminal power supply, and its positive and negative power supply terminals (7, 4) are respectively connected to the circuit ground of the single-chip microcomputer through capacitors IC10 and IC11. 5. The monolithic voltage monitoring device for a vehicle fuel cell according to claim 1, wherein the hardware interlock circuit uses a 2-input 4-channel NAND gate chip 74LS00 (I) and 2 4 Input 2-channel NAND gate chip 74LS20 (II, III); Each two input ends (1,2; 4,5; 9,10; 12,13) of 4 passages of NAND gate chip 74LS00 (I) mutually After connecting, connect to the P1.0~P1.3 pins of the single chip microcomputer, and the output terminals (3, 6, 8, 11) of each channel are respectively connected to the input terminals of the NAND gate chip 74LS20 (II, III); the NAND gate chip 74LS20 (II, III) Of the 4 input terminals of each channel, 3 pins are used to connect the output of the non-gate chip 74LS00 (I), and 1 pin is directly connected to one of the P1.0~P1.3 pins of the microcontroller , The connection combinations of the 4 channels are mutually exclusive, and the output of the NAND gate chip 74LS20 (II, III) is connected to the decoder enabling terminal in the optocoupler gating circuit. 6. A single-chip voltage monitoring device for vehicle fuel cells according to claim 1, characterized in that the AN communication of the CAN communication circuit adopts the TTCAN protocol. 7. The single-chip voltage monitoring device of a vehicle fuel cell according to claim 2, wherein the photoelectric isolation relay is an AQW214 photoelectric isolation relay, and the decoder is a 74HC154. 8. A single-chip voltage monitoring device for a vehicle fuel cell according to claim 3, wherein the resistors IR2 and IR3 are 0.1% precision resistors. 9. A single-chip voltage monitoring device for a vehicle fuel cell according to claim 4, wherein the resistors IR7 and IR8 are 0.1% precision resistors.

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