CN108761350A - A kind of fuel cell pack monomer voltage polling system with start and stop Balance route - Google Patents

Abstract

The invention discloses a fuel cell stack monomer voltage inspection system with start-stop equalization control, comprising: a fuel cell stack, an optocoupler gating circuit, a decoder module, a parity conversion module, a signal conditioning circuit, and an equalization circuit , balance control module, controller and CAN module. The optocoupler strobe circuit strobes each single battery in turn, the positive and negative relationship of the voltage signal is corrected by the odd-even conversion module, and the signal is input to the A/D converter of the controller through the signal conditioning circuit. The balance circuit consumes the remaining gas through energy-consuming resistors to avoid high potentials. When the battery cell is reversed, the parasitic diode can play a protective role. The invention has high measurement precision, fast measurement speed, strong communication capability and expandability, and meets the voltage detection requirements of fuel cell stacks. At the same time, in the start-stop phase, the consistency of the voltage balance of the single battery is significantly improved, and the formation of the hydrogen-air interface is effectively avoided to improve the service life of the stack.

Description

A fuel cell stack monomer voltage inspection system with start-stop equalization control

technical field

The invention relates to the technical field of voltage signal acquisition of an expandable series unit array, in particular to a fuel cell stack monomer voltage inspection system with start-stop equalization control.

Background technique

Energy storage system or energy conversion system is an important part of the energy field, among which energy storage batteries and fuel cells are widely used energy storage devices and energy conversion devices. A fuel cell is a device that directly converts the chemical energy in a fuel oxidant into electrical energy through an electrochemical reaction. Taking a hydrogen-oxygen fuel cell as an example, its product is only water, and it has the characteristics of high energy utilization and no pollution. Therefore, Known as the ultimate solution for new energy vehicles. Both energy storage batteries and fuel cells need to be connected in series or in parallel before they can be used in practice. In order to ensure the safety of the system, it is necessary to detect the single voltage signal of the fuel cell in real time. The single voltage signal of the fuel cell is small and has significant fluctuations. Therefore, the present invention mainly focuses on the detection of the voltage signal of the fuel cell.

The essence of fuel cell voltage detection is to expand the series cell array voltage signal acquisition. For the fuel cell voltage inspection system, there have been corresponding patents published, mainly including three categories: resistance voltage division and multi-channel analog switch method, optocoupler Relay method, special acquisition chip method. Chinese patent 1 (CN 201859204 U) proposes a multi-channel switch simulation method. This patent uses two multi-channel analog switches with a total of 32 channels, but only collects 15 single cells, and the utilization rate is low; secondly, 15 single-channel If the midpoint of the body is connected to the COM common end, there will be potential accumulation. Chinese patent 2 (CN 1746695 A) and Chinese patent 3 (CN 102288813 A) both use optocoupler relay schemes, which have advantages over multi-channel analog switches. Chinese patent 2 uses differential signals to collect single voltage, which can well eliminate Cumulative potential, but its absolute value circuit directly eliminates the negative signal, and there is no other logical means to analyze the signal, which is not conducive to system fault diagnosis; Chinese patent 3 can measure positive and negative signals, which can effectively make up for the shortcomings of Chinese patent 2, but Chinese patent 3 The method in which one end of the battery is grounded after strobing will cause potential accumulation, and secondly, the strobing switching process of this method is complicated. Chinese patent 4 (CN 105044440 A) uses the LTC6803 chip to collect fuel cell voltage. The LTC chip manual has stated that it has requirements for the total voltage of the measured object. It must ensure that the sum of the voltages of each cell is at least 10V to meet all electrical requirements. Specifications, but each LTC chip in patent 4 only supports 12 monomer voltage acquisitions, but the normal working voltage of fuel cell monomers is 0.6-0.8V, so the principle of this scheme is not feasible.

During the fuel cell start-up and shutdown process, the voltage of the fuel cell cells will be significantly different. The reasons for this phenomenon are, on the one hand, the differences in the inherent properties of the cells, and on the other hand, the uneven distribution of gas supply or consumption. Therefore, It will cause voltage fluctuation rate spikes and affect battery life. Secondly, during the start-up and shutdown of the fuel cell, a hydrogen-air interface will be generated inside the anode of the battery, which will cause an oxidation reaction in the anode of the battery, and eventually lead to a high potential at the cathode, which will cause the fuel cell to reverse its polarity, continuously corrode the catalyst carbon carrier, and seriously damage the Battery Life. Therefore, it is necessary to enter the necessary means to avoid the occurrence of the above phenomenon. At present, the commonly used method is to introduce an auxiliary load to consume the oxygen in the cathode, so as to effectively control the decay rate of performance. However, in this method, the auxiliary load is connected to both ends of the stack, and it is impossible to intervene locally on the fuel cell. In addition, once a reaction occurs extreme phenomenon, there is no corresponding protective measures.

Contents of the invention

The purpose of the present invention is to provide a fuel cell monomer voltage inspection system with start-stop balance control, which is used for voltage state detection and start-stop balance control of fuel cell fixed power supply and power supply, and effectively avoids potential dangers of fuel cell work and faults, making the fuel cell safer and more stable during use.

To achieve the above object, the present invention adopts the following technical solutions:

A fuel cell monomer voltage inspection system with start-stop equalization control, the system includes: fuel cell stack, optocoupler gating circuit, decoder module, parity conversion module, signal conditioning circuit, equalization circuit, equalization control modules, controllers and CAN modules. The optocoupler gating circuit gates the two ends of the single battery to realize the direct measurement of the voltage of the single battery. The decoder module and the controller are used to control the opening and closing of the optocoupler relay. Each unit includes 16 dual channels Optocoupler relays can collect 31 individual voltages. The odd-even conversion circuit is used to modify the positive and negative relationship of the differential signal. When the strobe number is odd, the positive pole is connected to CV+, and the negative pole is connected to CV-. When the strobe number is even, the positive pole is connected to CV-, and the negative pole is connected to CV+. In order to make the differential signal input by the signal conditioning circuit positive, use two optocoupler relays to correct the positive and negative relationship of the differential signal, so that the positive pole of each monomer is connected to OP_CV+, and the negative pole is connected to OP_CV-. The signal conditioning circuit converts the differential signal into a voltage range that the A/D collector of the controller can withstand, mainly including two stages of operational amplifiers, the first stage of operational amplifiers is a differential amplifier circuit, and the voltage between the non-inverting and inverting input terminals Diodes play a protective role to prevent excessive differential mode signals; the second stage is a voltage follower circuit, followed by a first-order RC low-pass filter to filter high-frequency signals, and the dual diodes at the output port clamp the output voltage at 0-5V. The balance circuit is used to consume the remaining gas through the energy-consuming resistor to avoid high potential. At the same time, when the battery cell is reversed, the parasitic diode can protect the battery. The balance control module is used to select and open the corresponding balance circuit according to the collected voltage, which is realized by using a four-channel MOS tube driver chip. The controller and CAN module are used for the acquisition of single voltage, equalization control and data transmission.

The optocoupler gating circuit is composed of 16 dual-channel optocoupler relays PMn (n=1,2,3,...,16), and the relay input terminal Bn (n=0,1,2,...,31) It is connected to the negative pole and positive pole of each single battery in turn, the output terminal of the relay on the lower side of PMn is connected to CV-, and the output terminal of the relay on the upper side of PMn is connected to CV+. The anode input terminals of the light emitting diodes are connected to the current limiting resistor, the output terminals of the light emitting diode cathodes on the lower side of the PMn are respectively connected to the decoder module XAn (n=0,1,2,...,15), and the output terminals of the light emitting diode cathodes on the upper side of the PMn The terminals are respectively connected with decoder modules XBn (n=0,1,2,...,15).

The odd-even converter module includes two dual-channel optocoupler relays PMOdd and PMEven, and the anode input terminals of the upper side light-emitting diodes of PMOdd and PMEven are connected to VCC, the upper cathode output terminal is connected to the lower anode output terminal, and the lower cathode output terminal is connected to VCC. The output terminals are respectively connected to the controller input terminals Cell_Odd and Cell_Even; the upper relay input and output terminals of PMOdd are respectively connected to CV+ and OP_CV+, and the lower relay input and output terminals are respectively connected to CV- and OP_CV-. The PMEven relay side is similar to PMOdd, only Interchange the positions of CV+ and CV-.

The signal conditioning circuit includes two stages of operational amplifiers U1, U2, the front end of U1 is connected to the differential signal (OP_CV+, OP_CV-) through precision resistors (R2, R3), and the differential signal is connected to a diode (D1, D2), R1, C1, and C2 form a filter circuit, the output of U1 is connected to the positive-phase input of U2, and the output of U2 is connected to the RC circuit (R6, C5), and then connected to the clamping dual diodes (D3, D4).

The equalization circuit is composed of MOS tubes, parasitic diodes, voltage regulator tubes, energy dissipation resistors, and current limiting resistors. The source of the MOS tubes is connected to the positive pole of the monomer, and one end of the energy dissipation resistors is connected to the drain of the MOS tubes, and the other end It is connected to the negative pole of the monomer, the gate of the MOS transistor is connected to the balance control module Sn (n=1,2,3,...,31) through the current limiting resistor, and the anode and cathode of the parasitic diode are respectively connected to the drain and source of the MOS transistor The anode of the Zener tube is connected to the gate of the MOS tube, and the cathode of the Zener tube is connected to the positive pole of the monomer.

The equalization control module is composed of 8 four-channel MOS transistor drive chips USn (n=1, 2, 3,..., 8), and the 8 chip output terminals (Y1, Y2, Y3, Y4) are respectively connected to Sn ( n=1,2,3,...,31) are connected, and the input control terminals (A1, A2, A3, A4) are respectively connected to the controller I/O port CTSn (n=1,2,3,...,31) The enabling terminals (1E2, 1E2, 2E1, 2E2) are connected to the 2.4V power supply, and VCC1, VCC2, and VCC3 are respectively connected to 5V, 20V, and 24V.

The advantage of the present invention compared with prior art is:

By adopting the technical scheme of the system, the present invention can not only quickly and accurately detect the voltage of the fuel cells, but also can significantly improve the consistency of the voltage balance of the cells in the start-stop phase. During start-up, the oxygen starvation phenomenon of the fuel cell is avoided; during shutdown, the equalization circuit consumes the remaining gas through the energy-dissipating resistor, avoids the occurrence of high potential, effectively avoids the generation of hydrogen-air interface, and prolongs the service life of the stack. When the hydrogen-air interface causes the reverse polarity of the battery cell, the parasitic diode can protect the battery.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the drawings that need to be used in the description of the embodiments.

Figure 1 is an overall architecture diagram of a fuel cell stack cell voltage inspection system with start-stop equalization control provided in an embodiment of the present invention;

Fig. 2 is a schematic diagram of a decoder module provided in an embodiment of the present invention;

FIG. 3 is a schematic diagram of a parity converter module provided in an embodiment of the present invention;

FIG. 4 is a schematic diagram of a signal conditioning circuit provided in an embodiment of the present invention;

Fig. 5 is a schematic diagram of an equalization control module provided in an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example

Figure 1 shows the overall architecture of the fuel cell stack monomer voltage inspection system with start-stop equalization control. The system includes: fuel cell stack, optocoupler gating circuit, decoder module, parity conversion module, signal A conditioning circuit, an equalizing circuit, an equalizing control module, a controller and a CAN module. The optocoupler gating circuit gates the two ends of the single battery to realize the direct measurement of the voltage of the single battery and solve the problem of potential accumulation. The decoder module and the controller are used together to control the opening and closing of the optocoupler relay. The unit includes 16 dual-channel optocoupler relays, which can collect 31 monomer voltages. The odd-even conversion circuit is mainly to modify the positive and negative relationship of the differential signal. When the strobe number is odd, the positive pole is connected to CV+, and the negative pole is connected to CV-. When the strobe number is even, the positive pole is connected to CV-, and the negative pole is connected to CV+. In order to make the differential signal input by the signal conditioning circuit positive, use two optocoupler relays to correct the positive and negative relationship of the differential signal, so that the positive pole of each monomer is connected to OP_CV+, and the negative pole is connected to OP_CV-. The signal conditioning circuit converts the differential signal into a voltage range that the AD collector of the controller can withstand, mainly including two stages of operational amplifiers, the first stage of operational amplifiers is a differential amplifier circuit, and the diode between the non-inverting and inverting input terminals acts as an amplifier. To protect and prevent the differential mode signal from being too large; the second stage is a voltage follower circuit, followed by a first-order RC low-pass filter to filter high-frequency signals, and the dual diodes at the output port clamp the output voltage at 0-5V. The purpose of the equalization circuit is mainly to consume the remaining gas through the energy-dissipating resistor and avoid high potential. At the same time, when the battery cell is reversed, it can protect the battery through the parasitic diode. The balance control module is mainly to select and open the corresponding balance circuit according to the collected voltage, which is realized by using a four-channel MOS tube driver chip. The controller and CAN module are used for the acquisition of single voltage, equalization control and data transmission.

Each inspection unit includes 16 optocoupler relays PMn (n=1,2,3,...,16), all of which use dual-channel optocoupler relays AQW214EHA, and the relay input terminals Bn (n=0,1,2,... ...,31) are connected to the negative pole and positive pole of each single battery in turn, the output terminal of the relay on the lower side of PMn is connected to CV-, and the output terminal of the relay on the upper side of PMn is connected to CV+. The anode input terminals of the light emitting diodes are connected to the current limiting resistor, the output terminals of the light emitting diode cathodes on the lower side of the PMn are respectively connected to the decoder module XAn (n=0,1,2,...,15), and the output terminals of the light emitting diode cathodes on the upper side of the PMn The terminals are respectively connected with decoder modules XBn (n=0,1,2,...,15).

Figure 2 shows the schematic diagram of the decoder module, which includes two 4-to-16 CD74HC154 decoders, and 4 chip-select input terminals CTAn (n=1,2,3,4) of the two decoders and CTBn (n=1,2,3,4) are connected to the controller I/O port, by setting the output level of the corresponding I/O port, select XAn (n=0,1,2,...,15 ) and XBn (n=0,1,2,...,15) each one way, thus select a single cell of the stack. When you want to strobe the monomer whose sequence number is (2n+1) (n=0,1,2,...,15), you need to control the decoder to set XA(n) and XB(n) as low level, When you want to strobe the monomer whose sequence number is (2n) (n=1,2,3,...,15), you need to control the decoder to set XA(n) and XB(n-1) as low level.

Figure 3 shows the schematic diagram of the odd-even converter module. This module includes two dual-channel optocoupler relays PMOdd and PMEven, both of which are dual-channel optocoupler relays AQW214EHA. The anode input terminals of the upper LEDs of PMOdd and PMEven are connected to VCC. The upper cathode output terminal is connected to the lower anode output terminal, and the lower cathode output terminal is respectively connected to the controller input terminals Cell_Odd and Cell_Even; the upper relay input and output terminals of PMOdd are respectively connected to CV+ and OP_CV+, and the lower relay input and output terminals are respectively connected to Connected with CV-, OP_CV-, PMEven relay side is similar to PMOdd, only the positions of CV+ and CV- are exchanged. After a certain cell is selected, the cell with an odd number (the positive pole is connected to CV+, the negative pole is connected to CV-), the cell with an even number (the positive pole is connected to CV-, the negative pole is connected to CV+), in order to facilitate the collection of CV+, CV- The voltage signal between them is collected by the parity converter module, and the positive pole is always connected to OP_CV+, and the negative pole is always connected to OP_CV-. When strobing odd-numbered cells, set Cell_Odd to 0 and Cell_Even to 1 through the controller; when selecting even-numbered cells, set Cell_Odd to 1 and Cell_Even to 0 through the controller.

Figure 4 shows the schematic diagram of the signal conditioning circuit. The voltage signal is connected to OP_CV+ and OP_CV- after passing through the parity converter circuit. In order to collect the voltage signal, the signal conditioning circuit uses two-stage operational amplifiers, and the first-stage operational amplifier U1 is a differential operational amplifier. , the second-stage operational amplifier U2 is a voltage follower, all of which use LM2094, the voltage signal is connected to the precision resistors (R2, R3) after being filtered by R1, C1, and C2, and connected between the non-inverting and inverting input terminals The diodes (D1, D2) play a protective role to prevent the differential mode signal from being too large. The output of U1 is connected to the positive phase input of U2, and the output of U2 is connected to the RC circuit (R6, C5), and then connected to the clamping double diodes (D3, D4) is connected to limit the output voltage between 0 and 5V to ensure the safety of the controller input.

The output signal Vin of the signal conditioning circuit is connected to the AD module of the controller. The controller is a 112-pin MC9S12XEP100, which is a 16-bit microprocessor and includes two 12-bit A/D modules, which can ensure high-precision voltage collection. At the same time, the optocoupler relay The switching speed is fast, so it can ensure the rapidity and accuracy of single voltage acquisition.

The above-mentioned components mainly meet the inspection of the fuel cell stack monomer voltage, and the equalization circuit and equalization module mainly guarantee the safety of the fuel cell during the start-stop process.

The equalization circuit is composed of MOS tube, parasitic diode, voltage regulator tube, energy dissipation resistor, and current limiting resistor. The source of the MOS tube is connected to the positive pole of the monomer, one end of the energy dissipation resistor is connected to the drain of the MOS tube, and the other end is connected to the monomer The negative electrode is connected, the gate of the MOS transistor is connected to the balance control module Sn (n=1,2,3,...,31) through the current limiting resistor, and the anode and cathode of the parasitic diode are respectively connected to the drain and source of the MOS transistor. The anode of the Zener tube is connected to the gate of the MOS tube, and the cathode of the Zener tube is connected to the positive electrode of the monomer. The MOS tube is P-type MOS tube Si2351DS, and Sn plays a role of digital output to control the on-off of the MOS tube. The power of the energy dissipation resistor is 1W. The voltage regulator tube is BZX384C12 to ensure the stability of the voltage difference between the positive pole of the monomer and the balance control terminal. Parasitic diodes ensure safety when the battery is reversed.

Figure 5 shows the schematic diagram of the equalization control module, which consists of 8 four-channel MOS tube driver chips USn (n=1, 2, 3,..., 8), all of which use SN75374 chips, and 8 chip output terminals (Y1 . 1, 2, 3,..., 31) are connected, the enabling terminals (1E2, 1E2, 2E1, 2E2) are connected to the 2.4V power supply, and VCC1, VCC2, and VCC3 are respectively connected to 5V, 20V, and 24V. By controlling the high and low levels of CTSn by the controller, the on-off of the MOS tube can be controlled by the drive chip, so as to ensure that the energy-dissipating resistor can consume the remaining gas during the start-stop process and avoid high potential.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention.

Claims (6)

1. A fuel cell monomer voltage inspection system with start-stop equalization control, characterized in that the system includes: fuel cell stack, optocoupler gating circuit, decoder module, parity conversion module, signal conditioning circuit , an equalizing circuit, an equalizing control module, a controller and a CAN module, wherein the optocoupler gating circuit gates the two ends of the single battery to realize the direct measurement of the voltage of the single battery; the described decoder module Together with the controller, it is used to control the opening and closing of optocoupler relays. Each unit includes 16 dual-channel optocoupler relays, which can collect 31 individual voltages; the odd-even conversion circuit is used to correct the positive and negative relationship of differential signals , when the strobe serial number is an odd-numbered cell, the positive pole is connected to CV+, and the negative pole is connected to CV-. When the strobe serial number is an even-numbered monomer, the positive pole is connected to CV-, and the negative pole is connected to CV+. Use two optocoupler relays to correct the positive and negative relationship of the differential signal, so that the positive pole of each monomer is connected to OP_CV+, and the negative pole is connected to OP_CV-; the signal conditioning circuit converts the differential signal into a value that the AD collector of the controller can bear The voltage range mainly includes two-stage operational amplifiers. The first-stage operational amplifier is a differential amplifier circuit, and the diode between the in-phase and inverting input terminals plays a protective role to prevent excessive differential-mode signals; the second-stage is a voltage follower The circuit is followed by a first-order RC low-pass filter to filter high-frequency signals, and the dual diodes at the output port clamp the output voltage at 0-5V; the equalization circuit is used to consume the remaining gas through the energy-consuming resistor to avoid the occurrence of high potential At the same time, when the battery cell is reversed, the parasitic diode can be used to protect the battery; the equalization control module is used to select and open the corresponding equalization circuit according to the collected voltage, and it is realized by using a four-channel MOS tube driver chip; The above-mentioned controller and CAN module are used for the acquisition of single voltage, equalization control and data transmission. 2. A kind of fuel cell monomer voltage inspection system with start-stop balance control according to claim 1, characterized in that, the optocoupler gating circuit is composed of 16 dual-channel optocoupler relays PMn (n=1 ,2,3,...,16), the relay input terminal Bn (n=0,1,2,...,31) is connected to the negative pole and positive pole of each single battery in turn, and the relay output terminal on the lower side of PMn is connected to CV- is connected, the output terminal of the relay on the upper side of PMn is connected to CV+; the anode input terminals of the light-emitting diodes are connected to the current limiting resistor, and the cathode output terminals of the light-emitting diodes on the lower side of PMn are respectively connected to the decoder module XAn (n=0,1,2, ..., 15) are connected, and the cathode output terminals of the light emitting diodes on the upper side of PMn are respectively connected to decoder modules XBn (n=0, 1, 2, ..., 15). 3. A fuel cell monomer voltage inspection system with start-stop balance control according to claim 1, wherein the parity converter module includes 2 dual-channel optocoupler relays PMOdd, PMEven, and PMOdd , The anode input terminals of the upper LED of PMEven are connected to VCC, the upper cathode output terminals are connected to the lower anode output terminals, and the lower cathode output terminals are respectively connected to the controller input terminals Cell_Odd and Cell_Even; the upper relay input and output terminals of PMOdd They are respectively connected to CV+ and OP_CV+, and the input and output terminals of the lower relay are respectively connected to CV- and OP_CV-. The PMEven relay side is similar to PMOdd, only the positions of CV+ and CV- are exchanged. 4. A fuel cell monomer voltage inspection system with start-stop equalization control according to claim 1, characterized in that, said signal conditioning circuit includes two-stage operational amplifiers U1 and U2, and the front end of U1 is passed through a precision resistor (R2, R3) are connected to the differential signal (OP_CV+, OP_CV-), the differential signal is connected to the diode (D1, D2), R1, C1, C2 form a filter circuit, the output of U1 is connected to the positive input terminal of U2, U2 The output terminal of the output terminal is connected with the RC circuit (R6, C5), and then connected with the clamping double diodes (D3, D4). 5. A fuel cell monomer voltage inspection system with start-stop equalization control according to claim 1, wherein the equalization circuit is composed of a MOS tube, a parasitic diode, a voltage regulator tube, an energy dissipation resistor, Composed of current limiting resistors, the source of the MOS tube is connected to the positive pole of the monomer, one end of the energy dissipation resistor is connected to the drain of the MOS tube, and the other end is connected to the negative pole of the monomer, the gate of the MOS tube is connected to the balance control module Sn through the current limiting resistor (n=1,2,3,...,31) are connected, the anode and cathode of the parasitic diode are respectively connected to the drain and source of the MOS tube, the anode of the Zener tube is connected to the gate of the MOS tube, and the cathode of the Zener tube is connected to the single connected to the positive pole of the body. 6. A fuel cell voltage inspection system with start-stop equalization control according to claim 1, wherein said equalization control module is driven by 8 four-channel MOS tubes USn (n=1 ,2,3,……,8), eight chip output terminals (Y1, Y2, Y3, Y4) are respectively connected to Sn (n=1,2,3,……,31), and the input control terminal (A1 , A2, A3, A4) are respectively connected to the controller I/O ports CTSn (n=1,2,3,……,31), and the enabling terminals (1E2, 1E2, 2E1, 2E2) are connected to the 2.4V power supply, VCC1, VCC2, and VCC3 are connected to 5V, 20V, and 24V respectively.