KR100857654B1 - Discharge control method of fuel cell-super capacitor hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a supercap discharge control method of a fuel cell supercap hybrid electric vehicle, and when a maintenance is required for maintenance of a vehicle that is a component of a fuel cell supercap hybrid system, a braking resistor, a chopper, a supercap, and a PDU is turned off before turning off the vehicle. Supercap discharge control method of fuel cell supercap hybrid electric vehicle that can discharge the high capacity supercap quickly and safely by the simple operation, and can effectively prevent the occurrence of dangerous accidents by simple operation. It is about.

Fuel Cell, Supercap, Hybrid, Power Down, Discharge

Description

Discharge control method of fuel cell-super capacitor hybrid electric vehicle

1 is a power net diagram of a fuel cell supercap hybrid electric vehicle;

2 is a flow chart of current during supercap discharge according to the present invention;

3 and 4 is a power supply state diagram according to the operation mode in the fuel cell supercap hybrid system,

5 is a view showing a fuel cell power supply state and a supercap discharge current flow state in a supercap discharge mode according to the present invention in a fuel cell supercap hybrid system;

6 is a flow chart showing a supercap discharge mode process of the present invention for maintenance,

Figure 7 is a flow chart illustrating in more detail the power down process in the supercap discharge mode according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 fuel cell 11 fuel cell stack

12: stack PDU 13: PDU

20: Super Cap 30: Drive Motor

31: MCU 40: Chopper

50: braking resistor 60: accessory load

61: 12V auxiliary battery 62: 24V auxiliary battery

63, 64: low voltage DC-DC converter 65: BOP components

66: high voltage DC-DC converter 68a: cooling pump

C1: Supercap main relay S1: Chopper precharge switch

S2: Chopper Discharge Switch

The present invention relates to a supercap discharge control method of a fuel cell supercap hybrid electric vehicle, and more particularly, to check the maintenance of the vehicle, which is a component of the fuel cell supercap hybrid system. It is configured to discharge the supercap by using the supercap and PDU, so that the high capacity supercap can be discharged quickly and safely, and the supercap discharge can be easily performed by simple operation, and the fuel cell supercap hybrid electric vehicle can effectively prevent the occurrence of accidents. It relates to a supercap discharge control method.

In general, fuel cells are not only highly efficient in generating electricity compared to conventional power generation methods, but also have no emission of pollutants due to power generation. Therefore, fuel cells are regarded as future power generation technologies. It is being actively researched as a power source for vehicles to solve the problem of global warming, which is emerging in the world.

A fuel cell converts chemical energy released in the process into electricity by oxidizing an active material such as hydrogen such as LNG, LPG, methanol, etc. through an electrochemical reaction, and can be easily produced in natural gas. Hydrogen and oxygen from the air are used.

However, when only an environmentally friendly fuel cell is used as a power source of an electric vehicle, the fuel cell is responsible for all of the loads constituting the electric vehicle, and thus, there is a disadvantage in that performance is deteriorated in a low operating area of the fuel cell. .

In addition, there is a problem in that the acceleration performance of the vehicle is deteriorated because a sufficient voltage required by the driving motor cannot be supplied due to an output characteristic in which the output voltage is drastically reduced in a high speed driving region requiring a high voltage.

In addition, when a sudden load is applied to the vehicle, the fuel cell output voltage suddenly drops and fails to supply sufficient power to the driving motor, thereby degrading the performance of the vehicle (a sudden load change because it generates electricity by a chemical reaction). Overloading the fuel cell.

In addition, since the fuel cell has a unidirectional output characteristic, energy drawn from the driving motor cannot be recovered when the vehicle is braked, thereby degrading the efficiency of the vehicle system.

As a solution to the above disadvantages, a fuel cell battery hybrid or a fuel cell supercap hybrid system in which a high voltage battery or a supercap is additionally installed as a separate vehicle power source in a fuel cell vehicle has been developed.

Here, the fuel cell supercap hybrid system is a system in which a supercap is mounted as a separate power source for providing power required for driving a motor in addition to a fuel cell as a main power source in a large vehicle such as a bus as well as a small vehicle. PowerNet diagram of a supercap hybrid electric vehicle.

Referring to the basic power net configuration of the fuel cell supercap hybrid system, the fuel cell 10 and the supercap 20 which provide the power required to drive the motor 30, and the motor controller (Motor Control Unit) controlling the operation of the motor (hereinafter referred to as MCU) 31), a chopper 40 for implementing a multi-function through the switching operation of the semiconductor switch (IGBT), and a braking resistor (50) related to auxiliary braking.

In addition, the parasitic load 60 of various accessory parts and fuel cell drive-related parts includes 12V and 24V auxiliary batteries 61 and 62 for supplying power to various parts mounted on the vehicle, and low voltage DC. Low Voltage DC-DC Converter (LV DCDC, LDC) (63,64) and High Voltage DC-DC Converter (HV DCDC, HDC) (66), Inverter (67), Fuel BOP (Balance Of Plant) parts (referring to the whole equipment such as APS, FPS, Cooling System, etc.) (65) necessary for driving the battery system, high voltage components and fuel cell cooling Components such as a cooling pump (for high-voltage component cooling and fuel cell cooling) 68a, an air conditioner 68b, and a power steering 68c.

In the powernet configuration of the fuel cell supercap hybrid system as shown, the supercap 20 together with the fuel cell mode and the fuel cell 10 are modes in which the motor 30 is driven only by the power provided by the fuel cell 10. In the hybrid mode in which the motor 30 is driven by the power provided, the low voltage DC-DC converters LV DCDC (14V) 63 and LV DCDC (28V) 64, high voltage, in addition to the power required for driving the motor. Through the DC-DC converter HV DCDC (350V) 66, inverter 67, 12V, 24V auxiliary battery (61, 62), fuel cell drive-related BOP components (65), cooling pump (68a), air conditioning ( 68b), a secondary current flows in the direction as indicated by the arrow of FIG. 1 for supplying high voltage power to the power steering 68c.

Meanwhile, the fuel cell supercap hybrid system applied to date has been mainly applied to small vehicles, and its voltage level is about 400V or less, and the engine room and the supercap are separated from each other due to the vehicle layout. It was performed without supercap discharge.

In addition, the supercap safety device is all relay switch, the self-discharge is also very large, the voltage drops a lot after several days.

However, in recent years, the self-discharge characteristics of the supercap have been greatly improved, and thus the voltage drop speed is slow. In particular, in the case of a high capacity supercap applied to a bus, the voltage typically reaches 700V to 800V.

In the case of buses, all high-voltage components, including the supercap, are mounted together in the engine room, and the vehicle is long during maintenance of high-voltage components, which may lead to dangerous accidents due to communication problems between front and rear workers.

Therefore, the present invention has been invented to solve the above problems, and if a check is required for maintenance of the vehicle, which is a component of the fuel cell supercap hybrid system, the brake resistor, chopper, supercap, and PDU are turned off before turning off the vehicle. By discharging the supercap, it is possible to discharge the high-capacity supercap quickly and safely, and the supercap discharge control method of the fuel cell supercap hybrid electric vehicle that can effectively prevent the occurrence of dangerous accidents by enabling the supercap discharge by a simple operation. The purpose is to provide.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In order to achieve the above object, the present invention comprises the steps of receiving a signal according to the on-operation of the discharge switch to determine whether the vehicle is parked and whether the speed; Determining the current driving mode if the vehicle is in the parking state and there is no vehicle speed, and if the current driving mode is in the hybrid mode, turning off the supercap main relay to cut off the supercap power; Discharging the supercap by turning on the discharging switch of the chopper at a duty of 100%, and then performing chopper control until the electrical energy of the supercap is reduced through the breaking resistor and the voltage drops to the set voltage; And performing a vehicle power down mode in the supercap discharge mode according to the supercap discharge completion signal when the supercap voltage drops to the set voltage. The supercap discharge control method of a fuel cell supercap hybrid electric vehicle is provided.

The method may further include performing cooling control to cool the chopper, the braking resistor, and the related electric component by the power supplied through the inverter from the fuel cell at the same time as the supercap discharge.

The performing of the vehicle power down mode in the supercap discharge mode may include: switching a low voltage DC-DC converter connected to an auxiliary battery to a boost mode; Maintaining a driving state of the high voltage unit while the voltage supplied from the auxiliary battery and boosted by the low voltage DC-DC converter is supplied to the high voltage unit; Turning off the stack PDU to cut off the power of the fuel cell stack; Transmitting a stop command for terminating the operation of the fuel cell to the fuel cell controller and turning off the high voltage component and terminating the operation of the fuel cell; Turning off the low voltage DC-DC converter.

In addition, the high voltage unit is characterized in that the BOP component including the air supply device (APS), hydrogen supply device (FPS), cooling device (TMS) required for driving the fuel cell system.

In addition, the high-voltage DC-DC converter connected to the high-voltage unit is characterized in that the low-voltage DC-DC converter is turned off while switching to the boost mode.

In addition, it is characterized by cooling the high-voltage electrical components including the motor, motor controller, converters, inverters by supplying each cooling device until the power of the fuel cell stack is cut off.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention relates to a supercap discharge control method of a fuel cell supercap hybrid electric vehicle, and when a maintenance is required for maintenance of a vehicle that is a component of a fuel cell supercap hybrid system, a braking resistor, a chopper, a supercap, and a PDU is turned off before turning off the vehicle. The present invention relates to a control technique for discharging a supercap using

In the case of a bus with a fuel cell supercap hybrid system, all high voltage components are installed in the engine room, and the voltage level can be up to 900V.

In addition, the supercap discharge process for vehicle maintenance should include control of peripheral cooling components since cooling of high voltage components should be considered.

In particular, the fuel cell supercap hybrid system is required to drive a fuel cell system including a high voltage unit, such as an air supply unit (APS), a hydrogen supply unit (FPS), and a cooling unit (TMS), when the vehicle is powered down by the supercap discharge process. The BOP components must be operated until the fuel cell is stopped normally, and the inverter must also be operated for a period of time to cool the high voltage components.

2 is a diagram illustrating a current flow state to a chopper-breaking resistor during supercap discharge and a current flow state to a BOP component according to a boost mode of a DC-DC converter connected to an auxiliary battery during a power-down process after completion of the supercap discharge. Indicates.

3 and 4 are power supply state diagrams according to driving modes in the fuel cell supercap hybrid system, which is a reference diagram for explaining each driving mode, and in particular, according to each driving mode of the fuel cell supercap hybrid electric vehicle. 3 illustrates a hybrid mode and FIG. 4 illustrates a fuel cell mode.

3 and 4, the various accessory parts 68a, 68b and 68c shown in FIG. 2 and the fuel cell drive related BOP part 65, and LV DCDCs 63 and 64 and HV DCDC 66 connected to the respective parts. , A parasitic load including an inverter 67 and the like is simplified and indicated by reference numeral 60.

5 is a view illustrating a fuel cell power supply state and a supercap discharge current flow state in a supercap discharge mode according to the present invention in a fuel cell supercap hybrid system, and FIG. 6 is a supercap discharge mode of the present invention for maintenance. 7 is a flowchart illustrating a process, and FIG. 7 is a flowchart illustrating a power down process in a supercap discharge mode according to the present invention in more detail.

In the fuel cell supercap hybrid electric vehicle shown in FIG. 2, a fuel cell mode in which the motor 30 is driven only by power provided by the fuel cell 10, and a super cap 20 together with the fuel cell 10 are provided. When operating in the hybrid mode in which the motor 30 is driven with the power to be operated, the LVDCDC 14V, which is a low voltage DC-DC converter, from the fuel cell 10 and the supercap 20 in addition to the power required for driving the motor. (63), LV DCDC (28V) (64), HV DCDC (350V) 66 (66), high voltage DC-DC converter, 12V, 24V auxiliary battery (61,62) and inverter cell driving through inverter 67 respectively. In order to supply high voltage power to the BOP component 65, the cooling pump 68a, the air conditioner 68b, and the power steering 68c, a secondary current flows in the direction shown by an arrow.

Hereinafter, the supercap discharge control process according to the present invention will be described in detail with reference to FIGS. 5 to 7.

The present invention is to control the discharge of the supercap 20 according to the hybrid and fuel cell mode by pressing the discharge switch in the driver's seat for 3 seconds when the maintenance of the high voltage components of the vehicle is required before the key off after driving the vehicle.

First, when the discharge switch is pressed for 3 seconds, the controller (eg, HCU) receives an ON operation state of the discharge switch. Accordingly, the controller determines whether the vehicle is parked and whether the speed is present.

Here, if the vehicle is in the parking state and there is no vehicle speed, the current driving mode is determined. If the current driving mode is the hybrid mode, the supercap main relay C1 is turned off (PDU off) to power the supercap 20 from the powernet. Disconnect

On the other hand, if the current operation mode is the fuel cell mode, the supercap main relay (C1) is already in the off state enters the next chopper run mode.

The chopper 40 includes two semiconductor switches, that is, a precharging switch S1 and a discharging switch S2 using IGBTs. In the state where the supercap power is cut off as described above, Turn on the discharging switch S2 to 100% duty, and then continue to perform chopper control until the electrical energy of the supercap 20 is reduced through the breaking resistor 50 so that the voltage drops to a set voltage, for example, 60V. do.

At this time, the supercap 20 continues to discharge as shown in FIG. 2 and FIG. 5.

The breaking resistor 50 converts electricity into thermal energy and continuously consumes electricity, and is used for discharging the supercap 20 in the present invention.

The braking resistor 50 is a device that is pre-installed in association with auxiliary braking of a motor in a fuel cell vehicle, and basically has a resistance in a pipe through which cooling water can flow.

At the same time, since the fuel cell 10 continues to operate, the cooling control is performed so that the chopper, the braking resistor, and other related electronics are cooled by the power supplied from the fuel cell 10 to the respective cooling devices through the inverter 67. Do this.

Thereafter, when the voltage of the supercap 20 drops to 60V, the vehicle enters the vehicle power down mode in the supercap discharge mode by the supercap discharge completion signal.

In this case, before the power of the fuel cell 10 (fuel cell stack 11) is cut off, various high voltages at which the temperature rises during operation of the controller (this may be another controller, for example, by the supercap discharge completion signal) are performed. Cooling control is performed to cool the electrical components, that is, high voltage electrical components such as motors, motor controllers, converters, and inverters.

The cooling process for lowering the temperature of the high voltage electric component is performed by controlling a cooling apparatus mounted in each component, and the cooling apparatus is driven by receiving power supplied from the fuel cell 10.

For cooling devices that perform cooling for each high voltage electric component, these cooling devices are basic components of an electric vehicle and related technologies are already known through a plurality of paths such as prior patents, and thus, detailed descriptions thereof will be omitted. Shall be.

As described above, when the cooling of the high voltage electric component is completed, the controller (for example, the HUC) performs the overall power down control.

In supercap discharge mode, the supercap power is already disconnected, so the low-voltage DC-DC connected to the 12V secondary battery 61 to drive the BOP components 65 necessary for driving the fuel cell until the operation of the fuel cell 10 is terminated. A high voltage DC-DC converter (HV DCDC 350V) directly connected to the BOP component 65 is performed to control the converter (LV DCDC 14V) 63 to the boost mode. 66 turns off to support the boost mode of low voltage DC-DC converter 63.

At this time, the 14V voltage output from the auxiliary battery 61 is boosted to a high voltage 350V for operating the BOP component 65 by the boost mode operation of the low voltage DC-DC converter (LV DCDC (14V)) 63, and the BOP The component 65 is driven at the 350 V voltage supplied from the secondary battery 61 through the low voltage DC-DC converter (LV DCDC 14V) 63.

Thereafter, the low voltage DC-DC converter (LV DCDC (28V)) 64 connected to the 24V auxiliary battery 62 is turned off, and the stack PDU 12 is turned off to cut off the power of the fuel cell stack 11. .

At this time, the BOP component 65 continues to be driven at the 350V voltage supplied through the low voltage DC-DC converter 63 from the 12V auxiliary battery 61.

Thereafter, a stop command for terminating the operation of the fuel cell 10 is transmitted to the fuel cell controller, whereby the fuel cell controller turns off all of the BOP parts 65 that are necessary for the operation of the fuel cell 10 and the fuel cell ( The operation of 10) ends.

Then, the remaining low voltage DC-DC converter (LV DCDC (14V)) 63 is turned off, and finally, the controller is turned off to complete all the power-down processes and the system is in a shutdown state.

As described above, according to the supercap discharge control method of the fuel cell supercap hybrid electric vehicle according to the present invention, if the inspection is necessary for maintenance of the vehicle, which is a component of the fuel cell supercap hybrid system, the braking resistor before turning off the vehicle, By discharging the supercap by using the chopper, the supercap, and the PDU, it is possible to discharge the high capacity supercap quickly and safely, and it is possible to effectively prevent the occurrence of dangerous accidents by enabling the supercap discharge by a simple operation.

In addition, there is a plan to reliably cool the high voltage components by using the fuel cell power when powering down in the supercap discharge mode, and to stably operate the BOP components for driving the fuel cell system until the fuel cell is normally shut down. As a result, abnormal power down of the fuel cell and each unit can be prevented, and problems such as fatal damage to each unit can be prevented.

Claims (6)

Determining whether the vehicle is parked and whether there is a speed by receiving a signal according to an on operation of the discharge switch; Determining the current driving mode if the vehicle is in the parking state and there is no vehicle speed, and if the current driving mode is in the hybrid mode, turning off the supercap main relay to cut off the supercap power; Discharging the supercap by turning on the discharging switch of the chopper at a duty of 100%, and then performing chopper control until the electrical energy of the supercap is reduced through the breaking resistor and the voltage drops to the set voltage; Performing a vehicle power down mode in the supercap discharge mode according to the supercap discharge completion signal when the supercap voltage drops to the set voltage; Supercap discharge control method of the fuel cell supercap hybrid electric vehicle comprising a. The method according to claim 1, Supercap discharge control of the supercap hybrid electric vehicle further comprising the step of performing a cooling control to cool the chopper, the braking resistor and the related electronics by the power supplied from the fuel cell through the inverter at the same time as the supercap discharge. Way. The method according to claim 1, Performing a vehicle power down mode in the supercap discharge mode, Switching the low voltage DC-DC converter connected to the auxiliary battery to a boost mode; Maintaining a driving state of the high voltage unit while the voltage supplied from the auxiliary battery and boosted by the low voltage DC-DC converter is supplied to the high voltage unit; Turning off the stack PDU to cut off the power of the fuel cell stack; Transmitting a stop command for terminating the operation of the fuel cell to the fuel cell controller and turning off the high voltage component and terminating the operation of the fuel cell; Turning off the low voltage DC-DC converter; Supercap discharge control method of a fuel cell supercap hybrid electric vehicle comprising a. The method according to claim 3, The high voltage unit is a supercap discharge control method for a fuel cell supercap hybrid electric vehicle, characterized in that the BOP component including an air supply device (APS), hydrogen supply device (FPS), cooling device (TMS) required for driving the fuel cell system. . The method according to claim 3 or 4, The high voltage DC-DC converter connected to the high voltage unit is turned off when the low voltage DC-DC converter is switched to the boost mode, supercap discharge control method for a fuel cell supercap hybrid electric vehicle. The method according to claim 3, A method for controlling supercap discharge of a fuel cell supercap hybrid electric vehicle, characterized by supplying power to each cooling device until the power of the fuel cell stack is cut off to cool high voltage electric components including a motor, a motor controller, converters, and inverters.

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