KR100829307B1 - Fault diagnosis control method for high voltage relay of hybrid electric vehicle - Google Patents

Abstract

A fault diagnosis control method for a high-voltage relay of a hybrid electric vehicle is provided to warn a driver of the fault state of a relay and to prevent a breakdown of parts, an electric shock, or a fire by stopping all functions of the vehicle of a high voltage system at the same time when a fault of the high-voltage relay is detected. A fault diagnosis control method for a high-voltage relay of a hybrid electric vehicle comprises a step for executing an initial process for receiving MCU(Motor Control Unit) DC(Direct Current)-link voltage from an MCU by a BMS(Battery Management System,13) and receiving a high voltage connection request signal of an HCU(Hybrid Control Unit,12), if an ignition key(11) is turned on and then comparing an MCU DC-link voltage value with a value output by multiplying a battery voltage measurement value and T(set constant) before a precharge relay on-command and a step for diagnosing that welding of a relay is failed, if the MCU DC-link voltage value is higher than a value of multiplication of a battery voltage measurement value and T.

Description

Fault diagnosis control method for high voltage relay of hybrid electric vehicle}

1A and 1B are diagrams each showing a relay circuit configuration and an operation sequence of a hybrid electric vehicle,

2 is a block diagram showing a circuit configuration of a high voltage system relay and components of a hybrid electric vehicle to which the present invention can be applied;

3 is a view for explaining a high voltage relay on sequence control process in a hybrid electric vehicle to which the present invention is applied;

4 to 6 are diagrams for explaining the principle of relay failure diagnosis according to the present invention,

7 is a flow chart showing the overall process of relay failure diagnosis according to the present invention.

<Explanation of symbols for main parts of the drawings>

12: HCU 13: BMS

14: high voltage battery 15: initial charge relay

16: main relay

The present invention relates to a high voltage relay fault diagnosis control method of a hybrid electric vehicle, and more particularly, the fault diagnosis of the initial charge relay and the main relay based on the MCU DC-link voltage value received from the MCU in the relay on sequence control process. It relates to a high voltage relay failure diagnosis control method of a hybrid electric vehicle configured to perform.

In general, a hybrid vehicle in a broad sense means to drive a vehicle by efficiently combining two or more different power sources, but in most cases, an electric motor driven by an electric motor driven by an engine and a battery that uses a fuel to obtain driving power A vehicle that obtains driving power is referred to as a hybrid electric vehicle (HEV).

In response to the recent demand for improving fuel economy and developing more environmentally friendly products, research on hybrid electric vehicles is being actively conducted.

Hybrid electric vehicles can form a variety of structures using engines and electric motors as power sources. Most of the vehicles studied so far employ either parallel or series.

Among them, the parallel type is used to charge the battery but directly drive the vehicle together with the electric motor. However, the parallel type has the disadvantage that the structure is relatively more complicated than the series type and the control logic is more complicated. Since the electric energy of the battery can be used at the same time, the energy can be efficiently used.

In particular, the optimum operating area of the engine and the electric motor is used to improve the fuel efficiency of the entire drive system, as well as to recover energy from the electric motor during braking, thereby enabling efficient use of energy.

The hybrid electric vehicle is equipped with a vehicle control unit (HCU) that controls the overall vehicle, and is provided with a controller for each device constituting the system.

For example, an engine control unit (ECU) for controlling the overall operation of the engine, a motor control unit (MCU) for controlling the overall operation of the electric motor, a transmission control unit (TCU) for controlling the transmission The battery management system (Battery Management System, BMS) for controlling the operation of the battery, the air conditioning controller (Full Auto Temperature Controller, FATC) in charge of the room temperature control is provided.

These controllers are connected to the high-speed CAN communication line around the vehicle controller, which is the upper controller, so that the upper controller transmits commands to the lower controller while transmitting and receiving information between the controllers.

As described above, in the hybrid electric vehicle, a plurality of controllers including the HCU as the upper controller perform cooperative control with each other.

For example, the HCU exchanges information with each controller through CAN communication and also controls subordinate controllers. The HCU communicates with the engine ECU from the engine ECU with engine torque and engine speed information, start key information, throttle / engine Water temperature (cooling water temperature) information, etc. is to be delivered, and the HCU is also to send the fuel injection command, engine stop command, fuel injection prohibition command, electric motor start information, idle stop information, etc. to the engine ECU. .

In addition, the HCU substantially controls the driving of the electric motor through the MCU. At this time, the MCU maintains the driveability by controlling the driving torque and the driving speed of the electric motor as the driving source according to the control signal applied from the HCU, which is the upper controller.

As described above, cooperative control between controllers is very important in a hybrid electric vehicle, and cooperative control between such controllers is performed in all cases from startup to when the user turns off the ignition key.

In addition, the hybrid electric vehicle is essentially equipped with a high voltage battery (main battery) for providing the driving power of the electric motor, while the high voltage battery is repeatedly supplied / discharged while driving the vehicle to supply the necessary power.

In motor assist, a high voltage battery supplies (discharges) electrical energy, and stores (charges) electrical energy during regenerative braking or when the engine is running.In this case, the BMS is a state of charge (SOC), available. It transmits charging power and available discharge power to HCU / MCU to perform battery safety and life management.

Meanwhile, high voltage relays are used in hybrid electric vehicles that use high voltage battery energy to control electrical connection between an energy storage medium (or a system where high voltage is always connected) and other systems.

The purpose of the high voltage relay is to secure complete electrical insulation between the systems and to secure electrical safety during key off, maintenance, and emergency situations. It also aims to prevent the occurrence of serious secondary accidents such as electric shocks and fires, and to block the dark current of high voltage batteries (main batteries).

Typical high voltage relays in a hybrid electric vehicle include an initial charge relay and a main relay, each of which uses an initial charge relay and a main relay, and one initial charge relay. And two main relays.

In this case, when one initial charging relay and one main relay are used, the main relay interrupts one of the + and-lines at the rear of the battery, and when the two main relays are used, the + and-lines at the rear of the battery. All will be cracked down.

Hereinafter, in the present specification, a main relay that regulates the + line of the battery rear end of the two main relays will be referred to as a '(+) stage main relay' and a main relay that regulates the − line '(-) stage main relay'. .

1A and 1B are diagrams illustrating a relay circuit configuration and an operation sequence of a hybrid electric vehicle, respectively, wherein three high voltage relays, that is, one initial state, are connected between the high voltage battery (main battery) 1 and the high voltage system 6. An example in which the charging relay 2 and the two main relays 4 and 5 are installed.

Referring to the relay operation sequence performed under the BMS control, first, when the IG is On, "(-) stage main relay 4 on-> initial charge relay 2-on-> peak by register 3 Relay on sequence control is performed in the order of (Peak) current limit → completion of charging of capacitor (7) → (+) stage main relay (5).

Then, after the initial charge relay (2) is off (off), when the IG off state, the relay-off sequence in which the (-) stage main relay 4 and the (+) stage main relay 5 are simultaneously turned off Control is performed.

In this relay operation sequence, the MCU DC-Link Voltage begins to rise at the on point of the initial charge relay and drops at the off point of the main relay.

On the other hand, the hybrid electric vehicle employing the high voltage relay system described above has the following problems.

Conventionally, there is only general on / off sequence control function of high voltage relay, but there is no fault diagnosis function for high voltage relay itself, so it is vulnerable to safety accident prepared by failure of high voltage relay, and fusion contact of high voltage relay before safety accident occurs. Fault conditions such as (Welding) (contact point melted between contacts, relay off impossible) fault, open fault (open contact normally open, relay on impossible) are not known.

Hybrid electric vehicles receive signals from various controllers to turn off the relays in the event of a problem to ensure electrical safety.However, if a problem occurs in the high voltage relay itself, relay control is impossible, thus achieving a unique function / purpose of high voltage. Due to the inability to secure insulation, secondary accidents such as electric shocks and fires as well as the first accident are inevitable.

For example, in case of relay fusion failure, the battery high voltmeter is always connected to the DC-link line and exposed to safety risks such as electric shock.In the case of relay open failure, powertrain electric drive parts such as motors, low DC-DC converters, air conditioner inverters, etc. Since the main function of the hybrid electric vehicle is not able to be performed, the main function of the hybrid electric vehicle is also lost, and it is impossible to identify the cause of failure.

Accordingly, the present invention has been invented to solve the above problems, and during the relay on sequence control process, the BMS can perform fault diagnosis of the initial charge relay and the main relay based on the MCU DC-link voltage value received from the MCU. It can be configured to alert the driver to a relay failure condition, thereby allowing the driver to be inspected for the vehicle so that the driver can be prepared for a safety accident quickly. The purpose of the present invention is to provide a method for controlling high voltage relay failure diagnosis of a hybrid electric vehicle that can stop a vehicle function and prevent a failure of an attached part, a vehicle function loss, an electric shock or a fire.

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

In order to achieve the above object, the high voltage relay fault diagnosis control method of the hybrid electric vehicle according to the present invention, when the ignition key (IG On) state, the BMS receives the MCU DC-link voltage from the MCU and the high voltage of the HCU Performing an initial process of receiving a connection request signal and then comparing the MCU DC-link voltage value with a 'battery voltage measurement value x T (setting constant)' before the initial charge relay on command; And diagnosing the relay fusion failure when the MCU DC-link voltage value is greater than the 'battery voltage measurement value x T'.

Preferably, the BMS stores the relay fusion failure information by itself and simultaneously transmits the relay fusion failure information to each controller including the HCU; And warning means operated by the controller receiving the BMS or the fault information to warn the driver of the relay fault condition and to stop all functions in the vehicle using the power of the high voltage battery.

And, if the MCU DC-link voltage value is "battery voltage measurement value x T" or less, turning on the initial charge relay (On); Then comparing the MCU DC-link voltage value with the 'battery voltage measurement value x T'; Subsequently, when the MCU DC-link voltage value is less than the 'battery voltage measurement value x T', diagnosing an open fault of the initial charging relay.

Here, the BMS stores the initial charge relay open failure information itself and simultaneously transmits to each controller including the HCU; And warning means operated by the controller receiving the BMS or the fault information to warn the driver of the relay fault condition and to stop all functions in the vehicle using the power of the high voltage battery.

And, if the MCU DC-link voltage value of the "battery voltage measured value x T" or more in the on state of the initial charge relay, turning on the main relay, and then off the initial charge relay; Then comparing the MCU DC-link voltage value with the 'battery voltage measurement value x T'; If the MCU DC-link voltage value is less than the 'battery voltage measurement value x T', diagnosing an open fault of the main relay;

Here, the BMS stores the main relay open fault information by itself and transmits the same to each controller including the HCU; And warning means operated by the controller receiving the BMS or the fault information to warn the driver of the relay fault condition and to stop all functions in the vehicle using the power of the high voltage battery.

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

The present invention is to implement a relay fault detection function in the high voltage relay sequence control process and to improve the control reliability and safety of the hybrid electric vehicle, and in particular, to perform the fault diagnosis of the high voltage relay in the relay on sequence control process. There is a characteristic.

First, in order to fully understand the present invention, a high voltage relay circuit configuration and an operation sequence of a hybrid electric vehicle to which the present invention can be applied will be described in more detail.

2 is a block diagram illustrating a circuit configuration of a high voltage system relay and a component of a hybrid electric vehicle to which the present invention can be applied, and FIG. 3 illustrates a high voltage relay on sequence control process in a hybrid electric vehicle to which the present invention is applied. It is a figure for demonstrating.

Referring to FIG. 2, as an example, the vehicle controller HCU 12 and the battery controller BMS 13 are configured to receive the start key 11 information, and include an ECU (engine controller), a TCU (transmission controller), The HCU 12 is configured to receive a signal from the airbag ECU (airbag controller).

In addition, the FATC 22, which is an air conditioner controller, transmits information such as an air conditioner operation state to the HCU 12 in the high voltage air conditioner part 21 system, and the MCU (motor controller) 18 of the high voltage driving part 17 system is BMS ( A relay off request signal to the BMS 13, between the HCU 12 and the BMS 13, the HCU 12 transmits a relay on / off request signal to the BMS 13, and the BMS 13 is relayed on. Send / off state information to the HCU 12.

Subsequently, it is the BMS 13 that substantially controls the on / off of the high voltage relay, that is, the initial charge relay 15 and the main relay 16, and the initial charge relay 15 is first turned on under the control of the BMS 13. In the ON state, when the capacitor 19 of the high voltage system is charged, the main relay 16 is turned on.

On the other hand, there are three control sequences of the high voltage relay, on, off, emergency off sequence, the fault diagnosis function of the present invention is performed in relation to the relay on sequence process.

A relay on sequence process will be described with reference to FIG. 3.

When the _IG KEY On signal is input (①), as an initial process, the BMS checks whether there is a problem in the relevant system and sends a BMS Ready signal indicating that there is no problem. Send it to each controller that needs it (②).

In response, the MCU checks whether there is a problem in the relevant system and sends a signal to the BMS indicating that there is no problem. The BMS checks the ready signal from the MCU and disables the relay off request (_MCU RLY_OFF_REQ). At the same time, MCU DC-Link Voltage is received (③).

Subsequently, the HCU checks whether there is a problem in the relevant system and transmits an HCU Ready signal and a high voltage connection request (HCU HV_ON_REQ) signal to the BMS, and the BMS sends a ready signal from the HCU and a relay off request ( _HCU RLY_OFF_REQ) When the deactivation state is confirmed (HCU HV_ON_REQ) signal (④), the initial process is terminated.

When the initial process is completed, the BMS performs relay on control. First, the initial charging relay is turned on (_Pre Relay Drive) (⑤), and then the initial charging state is checked (⑥). ), Turn on the main relay (_Main Relay Drive) (⑦), then turn off the initial charge relay (⑧), and send it to each controller that requires the main relay's ON status (BMS RLY_ON_STATE) (⑨). .

As such, in order to prevent the inrush current from flowing into the external system, the initial charge relay is first turned on before the main relay to form the MCU DC-link voltage (inverter cap voltage). After the risk of inrush current disappears, the initial charge relay turns off after the main relay turns on.

After the relay on sequence is completed, the cranking and driving of the electric motor and the operation of the powertrain electric drive parts are performed.

In the process of performing the above relay-on driving, each step of the initial process such as the transmission and reception of the ready signal may be changed, but each control within 300ms after the start-up key on to perform the transmission and reception of the ready signal.

In addition, in the checking step (⑥) of the initial charging state, if the 'MCU voltage measurement value × α (set constant)' is higher than the BMS voltage measurement value, it is determined as normal initial charging state. 600 ms.

On the other hand, after the initial charging relay is turned on in the relay-on sequence control process, the MCU DC-link voltage increases with time constants according to the R and C values, thus using the MCU DC-link voltage value received from the MCU. By comparing the current battery pack voltage value (the current battery voltage measurement value), the relay fault diagnosis can be performed.

4 to 6 are diagrams for explaining the principle of relay failure diagnosis according to the present invention.

First, referring to FIG. 4, if the BMS receives the MCU DC-link voltage (inverter cap voltage) from the MCU and determines that the voltage is already formed before the _Pre Relay Drive On command, the relay fusion failure Diagnosis is possible.

Referring to FIG. 5, if the BMS determines that the MCU DC-link voltage is not formed after the _Pre Relay Drive On command, it may be diagnosed as an open failure of the initial charge relay.

Referring to FIG. 6, if the BMS determines that the MCU DC-link voltage is discharged after _Main Relay Drive On and _Pre Relay Drive Off, it may be diagnosed as an open failure of the main relay. Do.

 And, Figure 7 is a flow chart showing the overall process of the relay failure diagnosis according to the present invention, it will be described as follows.

First, when the ignition is turned on (IG On) (S10), the relay on sequence control as described in FIG. 3 is performed, and the initial process proceeds first.

Referring to FIG. 7, the BMS checks for an abnormality of its own and confirms that there is no abnormality (BMS Ready On) (S11) and transmits a ready signal, and receives a ready signal indicating no abnormality from the MCU and the HCU (MCU). Ready On, HCU Ready On) Receives MCU DC-link voltage value (inverter cap voltage value) from MCU, confirms that relay off request is disabled (_MCU RLY_OFF_REQ Off, _HCU RLY_OFF_REQ Off) from HCU and MCU, and requests high voltage connection from HCU. When receiving the signal (S11 ~ S14), it is diagnosed whether the relay is fused based on the MCU DC-link voltage value.

At this time, if the MCU DC-link voltage value is greater than the 'battery voltage measured value (battery pack voltage value) x T (set constant)' (S15), since the voltage is already formed before the initial charge relay on command, Diagnosis as a relay fusion failure, BMS self-stores the relay fusion failure code and at the same time transmits the relay fusion failure code to each controller, including the HCU required (S16).

If the MCU DC-link voltage value is less than the 'battery voltage measurement value x T', the BMS performs relay on control because it is in a normal state, and at this time, the initial charging relay is preferentially turned on (S17).

When the MCU DC-link voltage value is less than 'battery voltage measured value x T' after the initial command of the initial charge relay (S18), the fault is diagnosed as an open fault of the initial charge relay, and the BMS opens the initial charge relay. While storing the fault code itself, and transmits the initial charge relay open fault code to each controller, including the HCU (S19).

If the MCU DC-link voltage value is 'battery voltage measurement value x T' or more, since the normal state, the main relay is turned on (S20), and then the initial charge relay is turned off (S21).

In this way, if the MCU DC-link voltage value is less than 'battery voltage measurement value x T' after the main relay on and initial charge relay off (S22), the main relay is diagnosed as an open fault, and the BMS detects the main relay open fault code. At the same time, the main relay open failure code is transmitted to each controller including the HCU at the same time (S23).

If the MCU DC-link voltage value is more than 'battery voltage measurement value × T', it is normal and transmits to the controller that needs the ON state (BMS RLY_ON_STATE) of the main relay (S24), thus relay on sequence It will be completed (S25).

In this manner, according to the present invention, in the relay on sequence control process, the BMS can perform troubleshooting of the high voltage relay based on the MCU DC-link voltage value received from the MCU.

In the present invention, the BMS detects three failure states of relay fusion, initial charge relay open, and main relay open, and immediately after the detection, the BMS transmits information on the relay failure to each controller, such as an HCU, via CAN communication. By receiving the controller to stop all the functions (vehicle hybrid function, etc.) in the vehicle using the power of the high voltage battery can be actively prepared for safety accidents.

In addition, after detection, the warning means in the vehicle is activated by the BMS or a specific controller that has received the fault information from the BMS (for example, the warning lamp on the vehicle cluster is turned on) to alert the driver to a relay failure condition. To receive it.

When a fault is detected, a fault code is stored in the controller such as HCU or BMS, and the fault code is divided into three fault items such as relay fusion, initial charge relay open, and main relay open. The vehicle can be repaired by checking the fault code through the equipment such as a car and replacing the relay.

As described above, according to the high voltage relay fault diagnosis control method of the hybrid electric vehicle according to the present invention, the BMS is based on the MCU DC-link voltage value received from the MCU during the relay on sequence control process of the initial charge relay and the main relay. By being configured to perform the troubleshooting, it is possible to warn the driver of the relay failure condition, thereby enabling the driver to be inspected for the vehicle so that the driver can be quickly prepared for safety accidents.

In addition, as soon as a high voltage relay failure is detected, all vehicle functions of the high voltage system can be stopped, thereby preventing an accident such as a failure of an attached component, a vehicle malfunction, an electric shock or a fire.

Claims (6)

When the ignition is on, the BMS goes through the initial process of receiving the MCU DC-link voltage from the MCU and receiving the HCU high voltage connection request signal, followed by the MCU DC-link before the initial charge relay on command. Comparing the voltage value with the 'battery voltage measured value x T (setting constant)'; Diagnosing the relay fusion failure if the MCU DC-link voltage value is larger than the 'battery voltage measurement value x T (setting constant)'; High voltage relay failure diagnosis control method for a hybrid electric vehicle comprising a. The method according to claim 1, Transmitting, by the BMS, the relay fusion failure information itself to each controller including the HCU; A warning means operated by the controller receiving the BMS or the fault information to warn the driver of the relay fault condition and to stop all functions in the vehicle using the power of the high voltage battery; High voltage relay failure diagnosis control method for a hybrid electric vehicle further comprising. The method according to claim 1, Turning on the initial charge relay when the MCU DC-link voltage value is less than 'battery voltage measurement value x T'; Then comparing the MCU DC-link voltage value with the 'battery voltage measurement value x T'; If the MCU DC-link voltage value is less than 'battery voltage measurement value x T', diagnosing an open fault of the initial charging relay; The high voltage relay fault diagnosis control method of a hybrid electric vehicle further comprising. The method according to claim 3, Transmitting, by the BMS, the initial charge relay open failure information to each controller including the HCU at the same time; A warning means operated by the controller receiving the BMS or the fault information to warn the driver of the relay fault condition and to stop all functions in the vehicle using the power of the high voltage battery; High voltage relay failure diagnosis control method for a hybrid electric vehicle further comprising. The method according to claim 3, If the MCU DC-link voltage value is 'battery voltage measured value × T' or more in the on state of the initial charge relay, turning on the main relay and then turning off the initial charge relay; Then comparing the MCU DC-link voltage value with the 'battery voltage measurement value x T'; Diagnosing an open fault of the main relay when the MCU DC-link voltage value is less than 'battery voltage measurement value x T'; High voltage relay failure diagnosis control method for a hybrid electric vehicle further comprising. The method according to claim 5, Transmitting, by the BMS, the main relay open failure information itself to each controller including the HCU; A warning means operated by the controller receiving the BMS or the fault information to warn the driver of the relay fault condition and to stop all functions in the vehicle using the power of the high voltage battery; High voltage relay failure diagnosis control method for a hybrid electric vehicle further comprising.

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