KR20150078810A - Method for controlling motor torque of electric vehicle - Google Patents

Abstract

The present invention relates to a motor torque control method when a resolver offset of an electric vehicle is corrected. More specifically, the purpose of the present invention is to provide the motor torque control method when the resolver offset of the electric vehicle is corrected to improve the sense of difference a driver feels through a motor torque control when the resolver offset of the electric vehicle is corrected during driving. Therefore, the present invention provides the motor torque control method when the resolver offset of the electric vehicle is corrected the driver is capable of discriminating and controlling the motor torque of a (-) torque area and motor torque of a (+) torque area after controlling the motor torque as 0 for a period by setting to an offset correction mode for resolver offset correction in a tip out state of accelerator pedal when a request of the resolver offset correction of a vehicle is made while driving.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a motor torque control method for correcting a resolver offset of an electric vehicle,

The present invention relates to a motor torque control method for compensating a resolver offset of an electric vehicle, and more particularly, to a motor torque control method for compensating a resolver offset of an electric vehicle The present invention relates to a motor torque control method.

An electric vehicle is an electric motor that uses an electric motor (drive motor) as a drive source. The electric vehicle is equipped with an inverter system for controlling a drive motor. The absolute angular position of the rotor of the motor used for motor control is detected And a resolver is used.

Specifically, the resolver is used to measure the absolute position of a rotor for a motor stator used in a hybrid automobile or an electric vehicle. In the measurement of the position of the rotor, the assembly tolerance between the resolver and the motor, Due to various causes such as the inaccuracy of the position, and the offset can not be used to measure the absolute absolute position of the rotor, which causes the motor to fail to operate normally.

Therefore, a technique for improving the offset error by correcting the offset of the resolver has been developed and applied.

As a conventional technique, Korean Patent Application No. 1020110126332 (control method of a vehicle equipped with a motor) discloses a technique for monitoring the resolver during traveling to determine whether or not the resolver offset is corrected.

In Korean Patent Application No. 1020110126332, a mode for determining and correcting a resolver offset in a zero torque control interval in which zero current control is possible is entered (resolver offset correction / diagnosis mode). In the case of an electric car, Since the torque control section occurs during a very short time period as shown in FIG. 1, the zero torque section must be secured arbitrarily in order to diagnose and compensate the resolver offset. Therefore, the section capable of determining the resolver offset can be extended Thereby securing time for diagnosing and correcting the resolver offset.

Unlike the conventional passive resolver offset correction method, the conventional technique described above has an advantage in that the offset occurrence of the resolver is automatically determined during running and the offset correction is performed. However, at least once per 1 driving cycle The maximum torque is maintained at 0 Torque, so that there is a disadvantage that the torque is maintained and a sense of shearing is generated during deceleration, such as a sense of shear and a sense of deceleration at two stages.

Generally, an electric car has no willingness to accelerate while driving, or it reduces the opening amount of the accelerator pedal to reduce the vehicle speed. In this case, when the pedal is fully released from the pedal, that is, when the opening degree of the pedal (APS) of the accelerator pedal is 0%, the creep torque of the electric car is changed to the negative (-) region to perform the coast regeneration do. As a result, the motor torque is actually in the (+) area, and the accelerator pedal opening amount (APS) is changed to 0%, and the area is rapidly reduced to the (-) area.

As described above, the main problem of the above-described prior art is that when the user goes into the resolver offset correction / diagnosis mode at the time of driving, the user feels a sense of heterogeneity. After tip-out, the motor torque decreases from the (+) to the (-) area and makes the user feel a sense of deceleration, and the user can feel the appropriate deceleration feeling without using the brake operation.

However, when entering the resolver offset correction / diagnosis mode, the user maintains zero torque for a certain period of time, so that the user does not maintain the deceleration sensation as much as desired, but maintains the acceleration and feeling of a throbbing feeling. However, I feel a sense of deceleration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide an engine control apparatus and a control method thereof, which can determine an optimal entry- The present invention provides a motor torque control method for compensating a resolver offset of an electric vehicle that differentiates a torque gradient from a motor torque slope in a (+) torque region, thereby improving a sense of heterogeneity in operability.

In the present invention, when a resolver offset correction request is made for a vehicle under driving, the motor enters the offset correction mode for resolver offset correction in the tip-out state of the excel pedal, ) Motor torque of the torque region different from the motor torque of the (+) torque region to control the motor torque during the resolver offset correction of the electric vehicle.

According to the present invention, it is determined whether or not the present motor torque is included in the entering torque range according to the vehicle speed range when the tip pedal of the excitation pedal is generated. If the current motor torque is included in the entering torque range, .

Preferably, the slope of the motor torque of the negative torque region is controlled so as not to change abruptly with respect to the slope of the motor torque of the positive torque region.

According to the motor torque control method for compensating the resolver offset of an electric vehicle according to the present invention, the user feels a stable deceleration feeling instead of a sudden two-step deceleration feeling that occurs when the user enters the offset correction mode conventionally, .

FIG. 1 and FIG. 2 are graphs showing torque behavior according to the vehicle speed of a motor mounted on an electric vehicle
3 is a graph showing the behavior of the motor torque during tip-out of the normally-operated excel pedal according to the prior art and the torque behavior upon mode entry for offset correction of the resolver
FIG. 4 is a graph showing the behavior of the motor torque during tip-out of the normal-time excel pedal according to the present invention and the torque behavior upon mode entry for offset correction of the resolver
5 is an exemplary diagram for explaining a motor torque control method for resolver offset correction of an electric vehicle according to the present invention.
6 is a flowchart for explaining a motor torque control method for resolver offset correction of an electric vehicle according to the present invention.
7 is an exemplary diagram for explaining a motor torque control method for resolver offset correction of an electric vehicle according to the present invention.
8 is a view showing the effect of the motor torque control method in compensating the resolver offset of the electric vehicle according to the present invention

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

The present invention is intended to improve the sense of heterogeneity felt by the driver through the control of the motor torque when diagnosing and correcting the resolver offset during the running of the electric vehicle.

In the present invention, in order to diagnose and correct the offset of the resolver during traveling, a zero torque maintaining period (interval) after the zero torque holding period (interval) to minimize the feeling of the driver feeling when the zero torque is arbitrarily maintained for a predetermined time, Differentiate the slope from the (+) area.

In the tip-out condition of the excel pedal during normal driving, the required torque (torque required for the motor) is calculated by subtracting the accelerator opening slope (the degree to which the APS pedal was stepped) and the tuned demand torque map ).

Conventionally, as shown in FIG. 3, when the resolver offset correction / diagnosis mode is entered, the motor torque of the (-) torque region and the (+) torque region is reduced along the same required torque map except for the zero torque holding period .

The driver maintains a constant torque. In the midst of driving, the motor torque decreases to 0 Torque when the tip of the Excel pedal is generated, and a feeling of deceleration is felt. At this time, if the motor torque of the (-) torque region is reduced again by maintaining the 0 torque for a predetermined time and at the same slope as the (+) torque region, heterogeneity occurs in terms of operability.

In the present invention, in order to improve such a sense of heterogeneity, the torque reduction slope when the motor torque enters the negative torque region is differentiated from the positive torque region. For this purpose, a resolver offset correction / diagnosis mode (hereinafter, ), It is possible to apply the required torque map to the motor controller at the time of entry.

In other words, in the present invention, when entering the offset correction mode in the tip-out state (APS 0) of the excel pedal during running, the second required torque map is used instead of the first required torque map used at normal time (+) Torque region of the torque region by decreasing the torque slope of the (-) torque region, thereby making it possible to feel a stable deceleration feeling instead of the abrupt two-stage deceleration feeling that occurs when the conventional offset correction mode is entered. The level of customer complaints can be minimized.

That is, in the present invention, only the torque slope of the (-) torque region is changed and controlled in order to secure an initial deceleration sense in terms of operability when entering the offset correction mode.

In the present invention, the entry condition of the offset correction mode is subdivided in order to minimize the driver's sense of throttle when the zero torque is arbitrarily maintained for a predetermined time for the resolver offset correction during driving.

As the entry condition, an entry vehicle speed and an entry torque, which are judged to have the greatest influence on the offset correction of the resolver, are set.

When entering the offset correction mode in the medium speed range (2000 to 4000 RPM or more), the vehicle vibration is larger than that in the low speed range (1000RPM) and the acceleration feeling is lower than the low speed range. (The vehicle speed range in which the offset correction mode is executed) and the section to be corrected (the vehicle speed range in which the offset correction mode is performed) are determined based on the vehicle speed need.

In the case of the vehicle speed section, there is an appropriate entering torque for entering the offset correction mode for each vehicle speed region.

Referring to FIG. 5, for example, when the Excel pedal is Tip out during traveling at a constant vehicle speed (T kph), it is set to transmit a command from the motor controller (MCU) that offset correction of the resolver is required It is possible to improve the drivability when the entering torque is maintained at the torque in the region between B and C Nm than the torque in the region between A and B Nm at the constant vehicle speed (T kph).

That is, when entering the offset correction mode, it is possible to determine the optimum entry-torque section for further improving the operability.

Therefore, according to the present invention, it is possible to realize an improved level of function in terms of improvement of the sense of heterogeneity by setting the optimal entry torque interval (entering torque range) when entering the offset correction mode according to each vehicle speed, Can be minimized.

For example, as shown in Table 1 below, it is possible to set the minimum entry torque and maximum entry torque that can enter the offset correction mode based on each vehicle speed. In this case, if the entry torque does not have a value between the minimum value and the maximum value, it is impossible to enter the zero torque control mode and the offset correction mode.

Hereinafter, the process of controlling the motor torque in diagnosing and correcting the resolver offset during traveling will be described with reference to FIG.

As shown in Fig. 6, the motor controller transmits a correction request signal to the vehicle controller for offset correction of the resolver.

When the vehicle controller receives the offset correction request of the resolver from the motor controller, the vehicle controller senses the tip-out state of the Excel pedal and determines whether or not the tip-out is performed.

In order to minimize the deceleration unevenness experienced by the driver when the tip of the accelerator pedal is tipped out, the vehicle controller interrupts the zero torque control in the regenerative braking mode and the braking mode and consequently does not enter the offset correction mode.

Accordingly, when the vehicle controller determines that the Excel pedal is in the tip-out state and transmits the determination result to the motor controller, in other words, if the vehicle controller transmits a signal for permitting entry into the offset correction mode at the request of the motor controller, The controller controls the subsequent process according to the tip-out determination result transmitted by the vehicle controller.

That is, if the motor controller recognizes the tip-off of the excel pedal by the vehicle controller, i. E. The motor controller only enters the tip-out when the excel pedal is inactive, i.e. the motor controller enters the offset correction mode from the vehicle controller If it is permitted, a request signal for entering the offset correction mode is generated, and it is determined whether or not the current motor torque during running is within the range of the entry torque for entering the offset correction mode.

At this time, the motor controller sets the optimum input motor torque range for entering the offset correction mode according to the vehicle speed region.

There is a torque range that has the least influence on the operability when entering the zero torque control mode (offset correction mode) for each vehicle speed region.

Accordingly, the optimum entry motor torque range is set according to the vehicle speed region, and the offset correction mode is entered within the entry motor torque range, thereby improving the drifting feeling.

Fig. 7 shows a case in which the present motor torque during running is included between a preset maximum entry-torque maximum value and an entry-torque minimum value.

As shown in Fig. 7, it is possible to enter the offset correction mode only when the current motor torque during running is included in the optimum entering torque range (interval between the maximum value and the minimum value).

It is determined whether or not the motor torque during running is included in the optimum entry motor torque range according to the vehicle speed range. If the motor torque during running is within the optimum entry motor torque range, the second required torque map is selected upon entering the offset correction mode Decide to use.

Then, it is determined whether or not the motor torque command (or the motor torque value) under control of the motor controller is 0. If the motor torque command is 0, the motor torque command is maintained at 0 for a predetermined time, To control the motor torque of the (-) torque region.

The second required torque map is set to be different from the motor torque slope of the (+) torque region and the motor torque slope of the (+) torque region except for the zero torque control period as one of the two required torque maps ).

The first required torque map, which is the other of the two required torque maps, is set to have the same motor torque slope in the (+) torque region and in the negative torque region except for the zero torque control period 4).

In particular, in the case of the second required torque map, the slope of the motor torque slope of the (+) torque region is smaller than the slope of the motor torque slope of the (+) torque region, The slope has a slope that does not change abruptly.

In the case where the motor controller does not request the resolver offset correction during the above-described procedure, the Excel pedal is not in the tip-out state, and the vehicle controller can not request the entry into the offset correction mode, When the motor torque command (motor torque value) is not 0, the motor torque of the (-) torque region is controlled based on the first required torque map when the motor torque is not within the motor torque range.

Further, before controlling the motor torque of the (-) torque region based on the second required torque map, the time for keeping the motor torque command at 0 determines the most preferable value through testing and sets it as a reference value.

The main problem in the prior art was that when the resolver offset was corrected during traveling, the driver would feel differently from the normal driving condition.

In the present invention, the torque condition entering the offset correction mode is limited according to the vehicle speed region and the torque gradient of the (+) torque region and the (-) torque region is differentiated, thereby minimizing the sense of heterogeneity caused by the offset correction of the resolver .

Meanwhile, FIG. 8 shows the effect of binarizing the required torque map used in entering and non-entering the offset correction mode.

8, when the torque slope of the positive torque region and the negative torque region is kept the same, the driver feels a two-stage deceleration feeling due to a sudden change in the deceleration feeling, The torque gradient of the (+) torque region and the torque region of the negative (-) torque region are differentiated and the torque gradient of the (-) torque region is not changed so rapidly as in the present invention, Thus, it can be seen that the sense of heterogeneity felt by the driver can be improved.

Claims (3)

If a request to compensate the resolver offset of a driving vehicle occurs, the motor enters the offset correction mode for resolver offset correction in the tip-out state of the Excel pedal, controls the motor torque to 0 for a predetermined time, And the torque is differentiated from the motor torque of the positive torque region to control the motor torque in the resolver offset correction of the electric vehicle.
The method according to claim 1,
The control unit determines whether the present motor torque is included in the entering torque range according to the vehicle speed range when the tip pedal is tipped out and enters the offset correction mode only when the current motor torque is included in the entering torque range. A motor torque control method for compensating a resolver offset of an electric vehicle.
The method according to claim 1,
And controlling the slope of the motor torque of the negative torque region so as not to be abruptly changed relative to the slope of the motor torque of the positive torque region.

Images