Disclosure of Invention
The invention aims to provide a hydrogen fuel cell system of a fuel cell and auxiliary power cell hybrid vehicle and an idle speed control method thereof, which realize zero power output of the hydrogen fuel cell system to a vehicle when the vehicle is in idle speed.
The technical scheme of the hydrogen fuel cell system FCS for realizing one purpose of the invention is as follows: the electric power output of the fuel cell stack is connected with a booster circuit, a fuel cell system controller FCCU, the output of the booster circuit comprises a high-voltage load connected with the inside of the fuel cell system, the electric power output of the whole vehicle is connected, the output of the booster circuit is also connected with a PTC heater, a control signal of the PTC heater is connected with the fuel cell system controller, and the PTC heater is used for consuming redundant electric power generated by the fuel cell stack when the vehicle idles, so that the electric power output driven by the fuel cell stack is zero.
The boost circuit is a DCDC circuit.
The data communication framework is that the fuel cell system controller FCCU realizes the interaction of data commands with other controllers of the vehicle through the CAN of the whole vehicle.
The hydrogen fuel cell system FCS has in-system CAN communication, and realizes interaction of data commands of the fuel cell system controller FCCU to devices in the system, including (a fuel cell stack, a PTC heater, a booster circuit, and a high-voltage load in the fuel cell system).
The further optimized technical scheme is as follows: a contactor K2 is connected between the output of the booster circuit and the PTC heater, and a main control contactor K1 is connected between the fuel cell stack and the booster circuit.
The further optimized technical scheme is as follows: when the vehicle is idling, the PTC heater sets the working power PsetPTC equal to the idling net output power of the fuel cell stack-the high-pressure load power in the fuel cell system.
The further optimized technical scheme is as follows: also comprises a PTC heater provided with a working power feedback controller for feedbackThe controller is used for obtaining the current power P of the PTC heaterPTCJudging the current PTC heater power PPTCWhether or not to set the operating power P with the PTC heatersetPTCSimilarly, the PTC heater power is adjusted to set the operating power PsetPTCAnd (6) outputting.
The further optimized technical scheme is as follows: it also includes a medium heat exchanger for heat exchange with the PTC heater.
The hydrogen fuel cell system FCS is only additionally provided with one path of PTC output of the boost conversion circuit, when a vehicle idles, the fuel cell stack is not stopped, and the zero power output of the fuel cell stack to the whole vehicle is realized under the condition that the energy is stored by the second energy storage device; meanwhile, the feedback controller of the PTC heater solves the problem that the fuel cell stack fluctuates in power output of the whole vehicle due to fluctuation of the fuel cell stack and/or high-voltage load power, and realizes follow-up of the power of the PTC heater, so that the power output of the whole vehicle of the fuel cell stack is always zero. Simple structure and high control efficiency.
The second purpose of the present invention is achieved by a method for controlling an idle speed of a fuel cell system; after the vehicle is in an idle state and the electric energy of the second energy storage device reaches a set value, the PTC heater in the fuel cell system is started to work, the redundant electric energy generated by the fuel cell stack is consumed, and the power P of the PTC heater is burntPTCThe further optimized technical scheme is as follows: the PTC heater works according to a set power, and the set working power PsetPTCFuel cell stack idle net output power-the high voltage load power within the fuel cell system.
The further optimized technical scheme is as follows: obtaining the current PTC heater power PPTCJudging the current PTC heater power PPTCWhether or not to set the operating power P with the PTC heatersetPTCSimilarly, the PTC heater is adjusted to set the operating power PsetPTCAnd (6) outputting.
The further optimized technical scheme is as follows: the PTC heater exchanges heat with the medium heat exchanger.
The further optimized technical scheme is as follows: obtaining net output power of fuel cell stack and/or high output power in fuel cell systemModifying PTC heater set operating power P, voltage load power, net stack output power, and/or high voltage load power variations within a fuel cell systemsetPTC。
The control scheme is simple, the response is quick, and the power P of the PTC heater is controlledPTCThe control adopts a feedback follow-up method, and under the condition of idling, the fuel cell stack and/or the fluctuation change of high-voltage load power ensure that the power output of the whole fuel cell stack is zero.
Detailed Description
The following detailed description is provided for the purpose of explaining the claimed embodiments of the present invention so that those skilled in the art can understand the claims. The scope of the invention is not limited to the following specific implementation configurations. It is intended that the scope of the invention be determined by those skilled in the art from the following detailed description, which includes claims that are directed to this invention.
The auxiliary energy source of the second energy storage device in this embodiment includes a power battery system BMS and a super capacitor + bidirectional DCDC system SCMS.
Specifically, as shown in fig. 1, the fuel cell system FCS100 includes a fuel cell stack 101, a power output of the fuel cell stack 101 is connected to a DCDC boost converter circuit 102, an output of the DCDC boost converter circuit 102 includes three paths, one path of the output is connected to a PTC heater 103, two paths of the output are connected to a high-voltage load 104 in the fuel cell system, and a third path of the output is a vehicle power output, and the fuel cell system FCS further includes a fuel cell system controller FCCU 105. The fuel cell system FCS is internally provided with a sub CAN network, and data instructions of the fuel cell system controller FCCU are interacted with high-voltage loads in the fuel cell system FCS through CAN in the fuel cell system FCS and devices in the system including a fuel cell stack, a PTC heater, a booster circuit and the fuel cell system.
For a finished automobile, the finished automobile comprises a fuel cell system FCS100, a finished automobile controller VCU200, a super capacitor + bidirectional DCDC system SCMS300, a power battery system BMS400, a finished automobile high-voltage distribution box PDU500, a motor control system MCU600, a finished automobile high-voltage load 700 and a driving motor 800.
And the ECUs transmit and receive information through a CAN bus, wherein a fuel cell system controller (FCCU), a power battery system (BMS), a whole vehicle high-voltage distribution box (PDU), a whole Vehicle Controller (VCU) and a super capacitor and bidirectional DCDC system (SCMS) are connected to the whole vehicle high-speed CAN.
As shown in fig. 2, in the fuel cell system FCS, a main control contactor K1 is connected between the fuel cell stack 101 and the DCDC boost converter circuit 102, a second contactor K2 is connected between the DCDC boost converter circuit 102 and the PTC heater 103, and a third contactor K3 is connected between the DCDC boost converter circuit 102 and the high-voltage load 104.
And the third output of the DCDC boost conversion circuit 102 is the power output of the whole vehicle and is connected with the whole vehicle high-voltage distribution box PDU 400.
In an embodiment, the power output of the power battery system BMS and the stage capacitor + bidirectional DCDC system SCMS are also connected to the input of the second contactor K2, respectively, the third contactor K3.
In an embodiment, the fuel cell system FCS further includes a medium heat exchanger that exchanges heat with the PTC heater; the media heat exchanger may be in communication with the fuel cell cooling system water passage to dissipate heat generated by the PTC heater through the fuel cell cooling system water passage, or in communication with an air conditioning system for heating (not shown).
In order to realize the servo of the PTC power, the present embodiment constructs a PTC power feedback controller, as shown in fig. 3, which includes a differentiator 1 for comparing the idle power of the fuel cell with the high-voltage load power in the fuel cell system, an output of the differentiator 1 is connected to a comparator 2, the output power information of the comparator 2, and the PTC controller 3 obtains the output power of the PTC in real time and feeds the output power back to the comparator 2. The feedback controller may be a physical entity structure or may be implemented based on software control. In the embodiment, the control method is realized by adopting a software algorithm in a fuel cell system controller (FCCU) and is realized by adopting PID algorithm control.
As shown in fig. 4, the control method of the present embodiment is as follows:
in a non-idle state;
the VCU firstly judges whether the whole vehicle is in an idling state according to gear information, vehicle speed information, accelerator pedal information, fuel cell system FCS working state and information that MCU feedback distortion demand is 0;
when the vehicle is in an idling state and the fuel cell system is in a starting state, the electric quantity of the power battery and the electric quantity of the super capacitor both reach a charging prohibition threshold, and the VCU judges whether the SOC electric quantity of the super capacitor is more than or equal to 90% and the SOC electric quantity of the power battery is more than or equal to 90% in the embodiment; the energy of the galvanic pile is stored to the auxiliary energy in a maximized mode, and the energy utilization rate of the system is improved.
Whether the whole vehicle is in a high-voltage state at the moment is judged according to the closed states of a main positive contactor and a main negative contactor fed back by the whole vehicle high-voltage distribution box PDU;
through the process, the VCU sends a power output mode command of the FCS idling 0;
as shown in fig. 5, after learning that main contactor K1 and PTC contactor K2 have pulled in the fuel cell DCDC boost converter circuit and that the PTC heater controller bus voltage is between 290V and 450V.
The fuel cell system controller FCCU enters an idling 0 power output mode and sends a PTC initial setting working power instruction;
the PTC heater operates at a power P based on the initial setting of the FCCUsetPTCCarrying out work; the set working power PsetPTCIdle net output power of the fuel cell stack-high voltage load power within the fuel cell system;
the idle net output power of the electric pile is acquired by the FCCU, the high-voltage load power in other fuel cell systems is acquired by electric appliances, the information is sent to a CAN bus inside the FCCU, and the FCCU finishes calculation and sending of the set working power of the PTC heater.
The fuel cell system controller FCCU calls a PTC power PID (proportion integration differentiation) adjusting algorithm to always maintain the PTC power to be set working power PsetPTC(ii) a In the process: judging the current PTC heater power PPTC(the power is uploaded to the FCCU after being detected by the PTC internal detection circuit) is equal to PsetPTCIf not, continuing to invoke the PID algorithm until the current PTC heater power PPTCIs equal to PsetPTC;
The fuel cell system may be placed in an idle net output power 0 mode.
Further, whether the net output power of the fuel electric pile and the high-voltage load power in the fuel cell system are changed or not is judged, if yes, the required PTC working power is also changed correspondingly, and if not, the idling net output power of the fuel cell system can be always 0.
If the net output power of the fuel cell stack and the high-voltage load power in the fuel cell system change, the latest PTC set working power P needs to be set again in an overriding mannersetPTCAt a new set operating power P of the PTC heatersetPTCAnd (4) working.
The heat generated by the PTC heater is carried away by the medium heat exchange device.
In a further embodiment, the power outputs of the super capacitor + the bidirectional DCDC system SCMS300 and the power battery system BMS400 are also respectively connected with the input end of the PTC contactor K2, so that the fuel battery system FCS can be heated by the PTC heater through the power outputs of the super capacitor + the bidirectional DCDC system SCMS300 and the power battery system BMS400 when the vehicle is in cold start. Namely, when the PTC heater enters a high-pressure preparation state and the starting environment temperature of the fuel cell system FCS is lower than-20 ℃, the second energy storage device outputs to the PTC heater to enable the PTC heater to be in full power output, and when the fuel cell system is normally and slowly started and the temperature rises to 20 ℃, the PTC heater is closed.