KR20100088387A - Limphome drive method of hybrid electric vehicle - Google Patents

Abstract

PURPOSE: A limp home operation method of a hybrid vehicle is provided to restrictively operate a hybrid function when two out of three current sensors inside a motor controller of the hybrid vehicle are malfunctioning. CONSTITUTION: A limp home operation method of a hybrid vehicle comprises the following steps: detecting the malfunction of a current sensor inside a motor controller; comparing the motor speed with the predetermined speed when just one current sensor is operating; selecting a secondary limp home mode with the minimum motor control operation; measuring the current value of the two broken current sensors based on the normal current sensor, the motor speed and the consumed power amount; and performing the motor control based on the two current values(S61).

Description

Limphome drive method of hybrid electric vehicle

The present invention relates to a method for driving a lymphatic groove in a hybrid vehicle, and more particularly, in a hybrid vehicle, a limited hybrid function is operated in the event of a failure of a current sensor essential for a motor controller to perform control of a driving motor. The present invention relates to a method of driving a lymphatic groove in a hybrid vehicle to enable lymphatic groove driving.

In general, a hybrid vehicle in a broad sense means to drive the vehicle by combining two or more different power sources efficiently, but in most cases, the engine and battery power are used to burn the fuel (fossil fuel such as gasoline) to obtain torque. Means a vehicle driven by an electric motor to obtain a, it is commonly referred to as a hybrid electric vehicle (HEV).

This hybrid vehicle is a futuristic vehicle that can improve fuel efficiency and reduce emissions by adopting not only an engine but also an electric motor as an auxiliary power source, and it is more active in response to the demand of the times to improve fuel efficiency and develop environmentally friendly products. Is going on.

Hybrid vehicles can form a variety of structures by using the engine and the electric motor (drive motor) as a power source, it is widely adopted in passenger cars due to the advantage that the mechanical energy of the engine and the electric energy of the battery can be used at the same time. It is becoming.

In particular, since the optimum operating area of the engine and the electric motor is used, fuel efficiency of the entire driving system is improved, and energy is recovered by the electric motor during braking, thereby enabling efficient use of energy.

The hybrid vehicle is equipped with a hybrid control unit (HCU), and has 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) (including an inverter) for controlling the overall operation of the driving motor, a transmission controller for controlling the transmission (CVT) (Transmission Control Unit (TCU)), a battery controller (Battery Management System (BMS)) that monitors and manages the battery status, and an air conditioner controller (Full Auto Temperature Controller, FATC) in charge of room temperature control.

Here, the HCU is a top-level controller in charge of driving control of each controller, hybrid driving mode setting, and overall vehicle control. Each of the controllers is connected to a high-speed CAN communication line centering on the HCU, which is the top-level controller. The upper controller is to transmit commands to the lower controller while exchanging information between them.

1 is a diagram illustrating a configuration of a hybrid vehicle, including an engine 11, an engine controller (ECU) 12, a drive motor 13, a motor controller (MCU) 14, a high voltage battery 15, and a battery. Controller (BMS) (not shown), high voltage breaker (main relay) 16, capacitor 17, Low Voltage DCDC Converter (LDC) 18, electric load 19, etc. are shown. The drive motor 13 can be driven and charged.

The motor controller 14 controls the drive motor 13 to drive and generate power by generating torque, and is composed of a controller 14a, a driver, a power supply, and the like.

On the other hand, in a typical hybrid vehicle, a three-phase permanent magnet synchronous motor (PMSM) is used as the driving motor, and the motor controller includes a current flowing in each motor phase, a magnet position in the motor, a motor speed, and a motor. The drive motor is controlled by using temperature as an essential input.

Among these, three current sensors (14b, 14c, and 14d in FIG. 1, current detection of three phases) are generally used to measure the current flowing in each phase of the motor. The current sensor of any one of the three current sensors is used. Even if a fault occurs or if only two current sensors are originally used (only two phase currents are detected), the normal motor control can be performed by the characteristic that the sum of three phase currents is always zero (see the following equation).

Iu + Iv + Iw = 0 (1)

Here, Iu represents the current in the U phase, Iv represents the current in the V phase, and Iw represents the current in the W phase.

Due to the above characteristics, only two current sensors may be used.

According to the above characteristics, for example, when only a current sensor of two phases of U and V is used or a failure occurs in the W phase 1 phase current sensor during the current detection of three phases, as shown in FIG. Normal operation can be performed by replacing the current value as follows.

Iw = -Iu-Iv (2)

However, during the failure of the current sensor in one phase, an additional failure occurs in the current sensor in the other phase, or the current sensor in one phase fails while only two current sensors are in use. In this case, the normal operation (motor control) of the above method is no longer possible.

In this case, the vehicle is normally driven to the nearest workshop in the emergency driving mode, that is, the limphome mode, in which the hybrid function is stopped and the vehicle is driven using only the engine.

As described above, even if a fault occurs in one of the three-phase current sensors, a normal motor control is performed by calculating the current of the faulted phase using the current value of the other two phases. In the case of the above-mentioned current sensor failure, a method of stopping the hybrid function and performing emergency operation using only the engine is used.

However, even in this case, if the engine speed is kept above a certain speed (speed at which the voltage above the counter voltage of the motor is generated) to force the battery to be charged, the high voltage battery is discharged and it is no longer possible to charge the 12V low voltage battery. Eventually, limp home driving using only the engine will be impossible. The same applies to the case of directly charging a low voltage battery without going through a high voltage battery (see Patent Application No. 2006-76040).

In addition, even if the engine speed is maintained above a certain speed, excessive fuel consumption occurs in the idle section and the low speed driving section, and the instability of the vehicle driving is increased.

Accordingly, the present invention has been invented to solve the above problems, the failure of the current sensor of one phase in addition to the failure of the current sensor of another phase, or the current sensor of one phase of using only two current sensors originally Even if a fault occurs and only the current sensor of another phase becomes available, the purpose is to provide a method for enabling a more stable lymph groove operation by operating a limited hybrid function.

In order to achieve the above object, the present invention comprises the steps of: a) determining a failure of the current sensor in the motor controller; b) comparing the motor speed with the set speed if it is determined that only the current sensor on one of the current sensors in the motor controller is operating normally; c) selecting a secondary lymphatic mode in which the minimum motor control is performed in consideration of the amount of power consumed by the vehicle electric load when the motor speed is less than or equal to the set speed; d) Estimates the current value of the remaining two phases in which the failure of the current sensor occurs based on the amount of power consumed by the vehicle electric load, the motor speed, and the current value of the normal current sensor, and the current value of the normal current sensor and the remaining two estimated The second lymph groove mode for performing motor control by inputting a current value of the phase is performed.

Here, step d) may include receiving power consumption by an electric vehicle load from an LDC in a motor controller; Determining a required torque for operating the lymph groove from the amount of power consumption received from the LDC and the motor speed; Extracting and generating the D-axis and Q-axis current commands from the current map from the required torque and the motor speed during the lymph groove operation; Estimating the current value of the remaining two phases in which the failure of the current sensor occurs using the current values of the D-axis and Q-axis current commands and the normal current sensor; And performing motor control by inputting a current value of the normal current sensor and an estimated current value of the remaining two phases as inputs.

In addition, the required torque during the lymph groove operation is calculated by dividing the amount of power consumption received from the LDC by the electric angular velocity of the motor and multiplying the set efficiency value.

In addition, estimating the remaining two phase current values from the current values of the D-axis and Q-axis current commands and the normal current sensor includes: calculating a current value A 'according to the D-axis and Q-axis current commands; Normalizing the current I _norm from the current value of the normal current sensor and the current value A '; _Arcsin the current I _norm to calculate phase θ, and calculating current values of the remaining two phases in which the failure of the current sensor occurs from the current value A 'and the phase θ. .

At this time, the current value of the current sensor 1, 2 that has a failure from the current value A 'and the phase θ is characterized by the following formula (E1) and formula (E2).

(E1): Current of current sensor 1 = A '· sin (θ + (2/3) π)

(E2): Current of current sensor 2 = A '· sin (θ- (2/3) π)

Accordingly, according to the method of driving the lymphatic groove of the hybrid vehicle according to the present invention, even if two current sensors of the three-phase current sensors in the motor controller of the hybrid vehicle fail, the limited hybrid function is operated so that the lymphatic groove is more stable and continuous. Operation is possible. Lymph groove operation of the present invention is a lymph groove operation in which a minimum motor control is performed in consideration of the amount of power consumed by the vehicle electric load, and stable lymph groove operation is possible even when only one current sensor operates normally.

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

The present invention relates to a method for enabling a more stable lymph groove operation by operating a limited hybrid function even if two current sensors of the three-phase current sensor in the motor controller of the hybrid vehicle fails.

Conventionally, when a fault in two or more phases of a three-phase current sensor in a motor controller of a hybrid vehicle occurs, the operation of the hybrid function becomes impossible and the limp home operation is performed by driving only the engine. Otherwise, it consumes all low voltage batteries (12V battery), which limits the operation time of the limp home. Even if the engine speed is kept above a certain speed, it causes a lot of inconvenience and anxiety for the driver due to the large fuel consumption and instability of the driving. do.

Accordingly, even if only one current sensor operates normally due to a failure of the current sensor in the motor controller of the hybrid vehicle, a method for enabling continuous lymph groove operation by a limited hybrid function is disclosed. That is, failure of one phase current sensor occurs in addition to the current sensor of another phase, or fault occurs in one phase current sensor while using only two current sensors. Even if it is, even one normal current sensor to enable the operation of the lymph groove by the hybrid function.

First, a configuration of an apparatus for emergency driving of a hybrid vehicle according to the present invention will be described. FIG. 3 is a block diagram showing a configuration of an apparatus for emergency driving according to the present invention. Fault determination unit 21 for determining the failure of the current sensor, operation mode selection unit 22 for selecting the operation mode, lymph groove mode selection unit 23 for selecting the lymph groove mode, LDC due to vehicle electric load Lymph groove operation torque determining unit 24 for determining the required torque during the lymph groove operation (secondary lymph groove mode) from the power consumption and the motor speed, current command generation unit for generating a current command for estimating the current value from the required torque (25) In the case of a current sensor failure (normal operation of two phase current sensors), a phase switching calculation section 26 for calculating a current value of a phase where a sensor failure has occurred for the phase switching operation shown in FIG.

Next, FIG. 4 is a flowchart illustrating an emergency driving method of the hybrid vehicle according to the present invention, and FIG. 5 is a flowchart illustrating a driving mode selection in the entire process of FIG. 4.

Basically, the failure determination unit 21 determines the failure of the current sensor in the motor controller (S10), and the operation mode is selected by the operation mode selection unit 22 from the result (S20). Here, as shown in FIG. 4, the hybrid function stops, the lymph groove operation, the phase switching operation, and the hybrid function normal operation, according to the failure of three current sensors that detect the current of each phase (U phase, V phase, W phase). Either operating mode is selected.

In the process of selecting an operation mode, when all three current sensors that detect current of each phase (U phase, V phase, and W phase) operate normally as shown in FIG. 5, the motor controller performs normal motor control. The hybrid function is normally operated (S34).

On the other hand, if all three current sensors are faulty, the hybrid function is stopped. At this time, since current detection and motor control are not possible, emergency operation of driving the vehicle using only the engine is performed as in the prior art (S31).

And, if any one of the three current sensor is determined to be a failure, the conventional phase switching operation is performed (S33), at this time, the phase switching calculation unit 26 as shown in Figure 2 failure of the current sensor The current value of the generated phase is calculated from the current values of the other two phases detected from the remaining normal current sensors. As a result, the normal operation is performed by performing motor control with input of the two phase current values detected by the normal current sensor and the one phase current value calculated therefrom.

As shown in FIG. 5, when two current sensors of the three current sensors in the motor controller are determined to be malfunctioning, that is, when only the current sensor on one of the current sensors in the motor controller is determined to be in normal operation, Lymph groove operation of the invention is selected (S32)

6 is a flowchart illustrating a process in which the lymph groove mode selection unit selects the lymph groove mode according to the speed of the driving motor in the case where the lymph groove operation of the present invention is selected, and sets the motor speed to the set speed A [rpm]. In comparison (S41), when the motor speed is higher than the set speed, the primary lymphoid mode without motor control is selected (S50). When the motor speed is lower than the set speed, the amount of power consumed by the electric load of the vehicle is considered. Secondary lymphatic mode in which minimal motor control is performed is selected (S60).

FIG. 7 is a flowchart illustrating a primary lymphatic groove mode in the present invention, and FIG. 8 is a flowchart illustrating a process of estimating a current value of a faulty phase of the current sensor in the secondary lymphatic groove mode.

In the primary lymph groove mode, the motor control is stopped (S51, S52), and forced charging of the low voltage battery (12V battery) is performed by the counter voltage in the PWM off state (S53, S54). On the other hand, in the second limp home mode, the current value of the remaining two phases of the failure of the current sensor is based on the amount of power consumption of the LDC, the motor speed (electric angular velocity), and the detection value detected by the normal current sensor. The motor control for the lymph groove operation is performed using the current value detected by the normal current sensor and the estimated current value (the lymph groove operation is performed by the limited hybrid function operation).

9 is a flowchart illustrating a process of generating a current command from the LDC power consumption in the present invention, as shown in the drawing, the motor controller receives power consumption P due to the electric vehicle load from the LDC (S71). ), And thus, the lymph groove driving torque determining unit 24 receives the torque required for the lymph groove driving from the power consumption amount P received from the LDC, the motor speed (electric angular speed) ω, and the efficiency (which is a preset value) η. That is, the lymphatic groove driving torque T _req is determined (S72). Thereafter, the current command generator 25 extracts the D-axis and Q-axis current commands I _d ^* and I _q ^* from the current map from the lymph groove operating torque P and the motor speed ω determined as described above. (Generated using interpolation in the current map) (S73).

The lymph groove driving torque is calculated by the lymph groove driving torque determining unit 24 receiving the power consumption amount P of the low voltage battery (12V battery) from the LDC by the electric angular velocity? Of the motor as shown in the following equation.

T _req = P / ω × η (3)

Where P is the power consumption of the low voltage battery, ω is the electric angular velocity of the motor, and η is the efficiency (typically 95%).

D- and Q-axis current commands I _d ^* and I _q ^* are generated from the current map by inputting the torque T _req calculated as described above and the electric angular velocity ω of the motor.

Then, using the D-axis, Q-axis current command (I _d ^* , I _q ^* ) generated as described above and the current value detected by a normal current sensor, two phase current values that cannot be detected due to sensor failure (that is, Motor control for the second lymph home mode operation by estimating the current value of the two phases in which the current sensor has failed and using the estimated two phase current value and the current value of the remaining one phase detected by the normal current sensor. Perform

The second lymph groove mode operation will be described in more detail as follows.

In the present invention, when a fault occurs in two of the three current sensors and only one current sensor becomes available, the current value of one phase detected by the normal current sensor and the estimated two phase currents Motor control is performed using the values to perform a limp home operation with limited hybrid function. At this time, the following characteristics of the three-phase permanent magnet synchronous motor is used.

The currents in each phase have a phase difference of 120 ° from each other. That is, if θ, θ1, and θ2 are phases of three phases, θ, θ1 = θ + (2/3) π, and θ2 = θ- (2/3) π.

In addition, the current measured by the normal one-phase current sensor can be expressed as follows.

Measured current of normal current sensor = A · sinθ (4)

Where A is the amplitude of the current

At this time, there is a difference of θ 'between the actual current phase and the phase obtained from the current motor speed as follows.

θ = ω t-θ '(5)

(Where ω is the electric angular velocity of the motor and t is the sampling time)

Ω can be expressed as follows.

ω = Vm × 60 / 2π × P (6)

(Where Vm is the rotational speed of the motor (or directly connected engine), P is the number of poles of the motor)

In addition, if the value of the current measured from a normally operating current sensor is I _measure , the normalized current I _norm can be obtained from the following.

I _norm = I _measure / A '(7)

Θ can be obtained as follows.

θ = arcsin (I _norm ) (8)

At this time, if the magnitude of the current to be generated by the current command is A ', it can be expressed as follows.

A '= SQRT {(I _d ^* ) ² + (I _q ^* ) ² } (9)

Where I _d ^* is the D-axis current command and I _q ^* is the Q-axis current command.

On the other hand, the current of the two phases in which the failure of the sensor can be expressed as follows.

Current of faulted current sensor 1 = A '· sin (θ + (2/3) π) (10)

Current of faulted current sensor 2 = A '· sin (θ- (2/3) π) (11)

That is, the electric current which flows in three phases becomes said Formula (3), Formula (9), and Formula (10).

In this case, in order to increase stability, various input values required for motor control may be limited. For example, compensation may not be performed through temperature, voltage, or the like.

In addition, since control instability increases when the motor speed is high, when the motor speed is higher than the set speed (A [rpm]) at which the voltage higher than the counter electromotive voltage of the motor is generated, natural forced charging occurs, so that the secondary lymphhome mode operation is performed. Is terminated and primary lymphocyte mode operation is performed.

Referring to Figure 8 describes the process of estimating the current value of the faulty phase of the current sensor in the second lymph groove mode, the motor control is started after entering the second lymph groove mode (S61, S62), PWM on (on) In the state, the current value A 'according to the current command is calculated from the D-axis and Q-axis current commands generated through the process of FIG. 9 as shown in Equation (9) (S63 and S64). Then, the normalized current I _norm is calculated from the current value A 'and the current value detected by the normal current sensor as shown in Equation (7) (S65).

Then, using the current I _norm calculated as above, the phase θ is calculated as shown in Equation (8) (S66), and the current value A 'and the phase θ as shown in Equation (10) and Equation (11). The current value of the two phases in which the failure of the sensor is calculated is calculated (S67).

In this way, the motor control is performed using the current value of one phase detected by the normal current sensor and the current value of the two phases calculated as described above, thereby enabling the lymph groove operation with limited hybrid function. .

The lymph groove operation is a lymph groove operation in which a minimum motor control is performed in consideration of the amount of power consumed by the vehicle electric load, and as a result, stable lymph groove operation is possible even when only one current sensor operates normally as described above. .

1 is a view showing the configuration of a hybrid vehicle,

2 is a flow chart showing that the phase change calculation is made in the event of failure of the current sensor in a hybrid vehicle,

3 is a block diagram showing the configuration of an apparatus for emergency operation according to the present invention;

4 is an overall flowchart showing an emergency driving method of a hybrid vehicle according to the present invention;

FIG. 5 is a flowchart illustrating a driving mode selection in the entire process of FIG. 4.

6 is a flowchart illustrating a process of selecting a lymph groove mode according to the speed of the driving motor by the lymph groove mode selection unit when the lymph groove operation of the present invention is selected;

7 is a flow chart showing a primary lymphatic mode in the present invention,

8 is a flowchart illustrating a process of estimating a current value of a phase in which a current sensor has failed in a second lymph groove mode of the present invention;

9 is a flowchart illustrating a process of generating a current command from the LDC power consumption in the present invention.

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

11: engine 12: ECU

13: drive motor 14: motor controller

14b, 14c, 14d: Current sensor 15: High voltage battery

18: LDC 21: fault detection unit

22: operation mode selection unit 23: lymph groove mode selection unit

24: Lymph groove operation torque determiner 25: Current command generation unit

26: phase switching calculation unit

Claims (5)

a) determining a failure of the current sensor in the motor controller; b) comparing the motor speed with the set speed if it is determined that only the current sensor on one of the current sensors in the motor controller is operating normally; c) selecting a secondary lymphatic mode in which the minimum motor control is performed in consideration of the amount of power consumed by the vehicle electric load when the motor speed is less than or equal to the set speed; d) Estimates the current value of the remaining two phases in which the failure of the current sensor occurs based on the amount of power consumed by the vehicle electric load, the motor speed, and the current value of the normal current sensor, and the current value of the normal current sensor and the remaining two estimated Performing a secondary lymphatic mode in which motor control is performed by inputting a current value of a phase; Lymphhome driving method of a hybrid vehicle comprising a. The method according to claim 1, Step d), Receiving the amount of power consumed by the vehicle electric load from the LDC in the motor controller; Determining a required torque for operating the lymph groove from the amount of power consumption received from the LDC and the motor speed; Extracting and generating the D-axis and Q-axis current commands from the current map from the required torque and the motor speed during the lymph groove operation; Estimating the current value of the remaining two phases in which the failure of the current sensor occurs using the current values of the D-axis and Q-axis current commands and the normal current sensor; Performing motor control by inputting a current value of the normal current sensor and an estimated current value of the remaining two phases; Lymphhome driving method of a hybrid vehicle comprising a. The method according to claim 2, The required torque during the lymph groove driving is calculated by dividing the amount of power received from the LDC by the electric angular velocity of the motor and multiplying the set efficiency value. The method according to claim 2, The step of estimating the current value of the remaining two phases from the current values of the D-axis, Q-axis current command and the normal current sensor, Calculating a current value A 'according to the D-axis and Q-axis current commands; Normalizing the current I _norm from the current value of the normal current sensor and the current value A '; _Arcsin the current I _norm to calculate a phase θ, and calculating current values of the remaining two phases in which the failure of the current sensor occurs from the current value A 'and the phase θ; Lymphhome driving method of a hybrid vehicle comprising a. The method according to claim 4, The current values of the current sensors 1 and 2 in which the failure occurs from the current value A 'and the phase θ are calculated by the following equations (E1) and (E2). (E1): Current of current sensor 1 = A '· sin (θ + (2/3) π) (E2): Current of current sensor 2 = A '· sin (θ- (2/3) π)

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