High-precision VNT control system based on fuel cell air compressor

Abstract

The invention relates to the field of fuel cells, in particular to a high-precision VNT control system based on a fuel cell air compressor. The circuit comprises a filtering module, an MCU module, a boost module, a switching power supply module and an under-voltage protection module. The boosting module is in a standby state and is not started when the power supply voltage is within 16-32, and is started to work when the power supply voltage is less than 16V, and the voltage is supplemented to 24V; the switching power supply module comprises a DC-DC module and a maintaining function module, and when the input voltage of the control system is too low due to sudden power failure of the voltage of a front-end small storage battery, the maintaining function module boosts the voltage to more than 16V through a boosting module; and the under-voltage protection module works when the voltage boosting module is insufficient to meet the voltage required by the system due to over-low power supply voltage. According to the invention, the communication is stable, the anti-interference capability is strong, the power failure maintenance can be carried out, the direct current motor of the VNT actuator is protected, the control stability and accuracy of the VNT actuator are ensured, and the H-bridge driving capability is relatively high.

Description

Technical Field

[0001] The invention relates to the field of fuel cells, and in particular to a high-precision VNT control system based on a fuel cell air compressor. Background Art

[0002] In the fuel cell system, in order to achieve the goals of cost saving, high efficiency and energy recovery, more and more manufacturers have adopted turbine air compressors. Compared with conventional centrifugal air compressors, the main difference between turbine air compressors and conventional centrifugal air compressors is the addition of energy recovery function. In the turbine air compressor system, the VNT (variable nozzle turbine) actuator is used to achieve energy recovery, so the control of the VNT actuator is particularly important. In the existing turbine air compressor control system, the VNT actuator responsible for the energy recovery function is controlled by the fuel cell controller FCU to achieve the control of the VNT actuator opening.

[0003] The VNT actuator has two parts inside, namely the DC motor control module and the motor rotation angle feedback module. Currently, it has the following shortcomings:

[0004] 1. The DC motor module in the existing VNT actuator is driven and controlled by the fuel cell controller FCU-H bridge. If the system is in operation and the FCU encounters interference, or the wiring harness is loose, causing the H-bridge drive pin of the FCU to be interfered, the DC motor in the VNT actuator may be stuck or stop suddenly.

[0005] 2. The H-bridge driving capability of the existing fuel cell controller FCU on the market is generally low, while the H-bridge driving capability required by the DC motor in the VNT actuator of the common turbine air compressor on the market is greater than the H-bridge driving capability of the FCU. Therefore, the H-bridge driving capability of the existing fuel cell controller FCU is not sufficient to support the VNT actuator to use a more efficient DC motor.

[0006] 3. Since the FCU and the air compressor are two components, there will be a long distance between them in the system distribution, and the H-bridge drive harness required by the VNT actuator comes from the FCU, which makes these two H-bridge drive lines easily interfered by other harnesses in the system, resulting in reduced opening control accuracy and control speed of the VNT, which affects the energy recovery of the air compressor and the life of the air compressor control system. Summary of the invention

[0007] The purpose of the present invention is to address the problems existing in the background technology and propose a high-precision VNT control system based on a fuel cell air compressor, which has stable communication, strong anti-interference ability, can perform power-off retention, protect the DC motor of the VNT actuator, ensure the stability and accuracy of the VNT actuator control, and has a high H-bridge driving capability.

[0008] The technical solution of the present invention is a high-precision VNT control system based on a fuel cell air compressor, comprising a filter module, an MCU module, a boost module, a switching power supply module and an undervoltage protection module; the filter module comprises a protection circuit and a filter circuit; the MCU module monitors the control system and is connected to the fuel cell FCU for communication; the boost module is in standby mode and does not start when the power supply voltage is within 16-32, and starts working when the power supply voltage is less than 16V, and replenishes the voltage to 24V; the switching power supply module comprises a DC-DC module and a holding function module, the DC-DC module reduces the voltage of the front-end input current and supplies power to the control system and the MCU module, when the front-end small battery voltage suddenly loses power and causes the input voltage of the control system to be too low, the voltage detection module of the holding function module detects that the input voltage is too low, and the voltage is increased to above 16V through the boost module; the undervoltage protection module works when the boost module is insufficient to meet the voltage required by the system due to the low power supply voltage, and feedback is given to the MCU module, so that the control system loses power in an orderly and safe manner.

[0009] Preferably, the protection circuit includes a fuse, a varistor and a discharge chip.

[0010] Preferably, the filter circuit is a Π-type filter circuit, comprising a plurality of X filter capacitors and Y filter capacitors.

[0011] Preferably, the MCU module communicates with the fuel cell FCU via CAN.

[0012] Preferably, when the communication between the MCU module and the fuel cell FCU is abnormal, the control system maintains normal H-bridge drive within a preset t seconds. If no message is received after t seconds, a fault code is reported and the load is gradually reduced to 0 within t seconds. If a message is received within t seconds, the message instructions are implemented.

[0013] Preferably, the DC-DC module steps down the 24VDC input from the front end to 5VDC to power the control system, and steps down to 3.3VDC to power the MCU module.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] 1. The control system of the present invention is a breakthrough improvement from 0 to 1, and the H-bridge driving capability of the present invention is relatively high.

[0016] 2. The control system of the present invention communicates with the fuel cell controller FCU via CAN signals, and the communication is more stable and anti-interference, which can reduce the interference of the system on the VNT actuator, make the control of the VNT actuator more stable, and improve the accuracy of the VNT actuator control.

[0017] 3. When the fuel cell FCU is disturbed or the wiring harness is loose, causing the FCU to reset, the control system of the present invention can perform power-off retention, allowing the DC motor of the VNT actuator to gradually reduce the load until it stops, which greatly protects the DC motor of the VNT actuator. When voltage drops, load dump surge voltage shocks and other interferences occur in the power supply circuit, the DC motor of the VNT actuator will not be affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention;

[0019] Figure 2 This is the circuit diagram of the filter module. DETAILED DESCRIPTION

[0020] like Figure 1 and Figure 2 As shown, the high-precision VNT control system based on a fuel cell air compressor proposed in this embodiment includes a filter module, an MCU module, a boost module, a switch power supply module and an undervoltage protection module.

[0021] The filter module includes a protection circuit and a filter circuit. The protection circuit includes a fuse, a varistor and a discharge chip. The filter circuit is a Π-type filter circuit, including multiple X filter capacitors and Y filter capacitors, which has a good inhibitory effect on the conducted emission from the power line and enhances the system EMC anti-interference ability.

[0022] The switch power supply module includes a DC-DC module and a holding function module. The DC-DC module steps down the 24VDC input from the front end to 5VDC to power the control system, and steps down to 3.3VDC to power the MCU module. The DC-DC module can use the recommended circuit of the DCDC chip, and the chip can use the SBC chip of Infineon. When the voltage of the front-end small battery suddenly loses power and causes the input voltage of the control system to be too low, the voltage detection module of the holding function module detects that the input voltage is too low, and the voltage is increased to above 16V through the boost module, realizing the voltage holding function, so that the system can be powered off in an orderly manner when the power suddenly loses power, protecting the system.

[0023] The MCU module monitors the control system and is connected to the fuel cell FCU via CAN communication. The chip can be Infineon BTN7971B. When the MCU module communicates abnormally with the fuel cell FCU, the control system is maintained normally and the H-bridge is driven within the preset t seconds. If no message is received after t seconds, a fault code is reported and the load is gradually reduced to 0 within t seconds. If a message is received within t seconds, the message instruction is implemented.

[0024] The boost module is used as a monitoring module for the controller voltage. The chip can be UC3842. The boost module will not start when the supply voltage is between 16-32V. It will start working when the supply voltage is less than 16V, replenishing the voltage to about 24V to maintain the normal operation of the system until the supply voltage returns to normal. When the power supply is cut off due to problems such as the front end or wiring harness, the supply voltage will be less than 16V.

[0025] The undervoltage protection module works when the boost module is insufficient to meet the voltage required by the system due to the low supply voltage, and the feedback is sent to the MCU module, and the control system is powered off in an orderly and safe manner. When the supply voltage disappears directly and the power is suddenly lost, the boost module can no longer meet the boost requirements, the undervoltage protection module is activated, and the control system is powered off in an orderly and safe manner, which also protects the DC motor in the VNT actuator.

[0026] The working principle of the present invention is as follows: when the fuel cell system is started, the fuel cell FCU sends instructions to the PCU air compressor controller, the air compressor starts, and when the speed reaches the set value, the energy recovery function is started. The fuel cell FCU sends instructions to the MCU module in the present invention through the CAN network. After receiving the instructions, the MCU module monitors each protection module, the control system starts working, and outputs the H-bridge drive current to the DC motor in the air compressor VNT actuator for driving.

[0027] The systems on the market do not have the MCU module of the present invention. Usually, the H-bridge attached to the fuel cell FCU is used directly to drive and control the DC motor in the VNT actuator, and the driving capability is relatively low. The control system of the present invention is a breakthrough improvement from 0 to 1. The driving capability of the H-bridge of the present invention is relatively high, and it can be improved by changing the structure of the internal circuit, chip, etc. The control system of the present invention also has good EMC performance (Electromagnetic Compatibility) and high reliability.

[0028] The control system of the present invention communicates with the fuel cell controller FCU via CAN signals. Compared with the traditional control strategy of driving the DC motor of the VNT actuator through H-bridge hard wire, the present invention adopts CAN signal communication, which is more stable and anti-interference, and can reduce the interference of the system on the VNT actuator, making the control of the VNT actuator more stable, and improving the accuracy of the VNT actuator control. When the fuel cell FCU is disturbed or the wiring harness is loose, causing the FCU to reset, the control system of the present invention can perform power-off retention, allowing the DC motor of the VNT actuator to gradually reduce the load until it stops, which greatly protects the DC motor of the VNT actuator. When voltage drops, load dump surge voltage shocks and other interferences occur in the power supply circuit, it will not affect the DC motor of the VNT actuator.

[0029] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A high-precision VNT control system based on a fuel cell air compressor, characterized in that: include: A filter module, which includes a protection circuit and a filter circuit; MCU module, which monitors the control system and communicates with the fuel cell FCU; The boost module is in standby mode when the supply voltage is between 16 and 32V, and starts working when the supply voltage is less than 16V to supplement the voltage to 24V. The switching power supply module includes a DC-DC module and a holding function module. The DC-DC module reduces the voltage of the front-end input current and supplies power to the control system and the MCU module. When the front-end small battery voltage suddenly loses power and causes the input voltage of the control system to be too low, the voltage detection module of the holding function module detects that the input voltage is too low and increases the voltage to above 16V through the boost module. The undervoltage protection module works when the boost module is insufficient to meet the voltage required by the system due to the low power supply voltage, and feeds back to the MCU module to control the system to power off in an orderly and safe manner.

2. A high-precision VNT control system based on a fuel cell air compressor according to claim 1, characterized in that: The protection circuit includes a fuse, a varistor and a discharge chip.

3. A high-precision VNT control system based on a fuel cell air compressor according to claim 2, characterized in that: The filter circuit is a Π-type filter circuit, including a plurality of X filter capacitors and a Y filter capacitor.

4. A high-precision VNT control system based on a fuel cell air compressor according to claim 1, characterized in that: The MCU module communicates with the fuel cell FCU via CAN.

5. A high-precision VNT control system based on a fuel cell air compressor according to claim 1, characterized in that: When the communication between the MCU module and the fuel cell FCU is abnormal, the control system maintains normal H-bridge drive within the preset t seconds. If no message is received after t seconds, a fault code is reported and the load is gradually reduced to 0 within t seconds. If a message is received within t seconds, the message instructions are implemented.

6. A high-precision VNT control system based on a fuel cell air compressor according to claim 1, characterized in that: The DC-DC module steps down the 24VDC input from the front end to 5VDC to power the control system, and steps down to 3.3VDC to power the MCU module.

Images