KR20200101612A - Method and apparatus for controlling mild hybrid vehicle - Google Patents

Abstract

A method for controlling a mild hybrid system according to an embodiment of the present invention uses equivalent fuel consumption, which is a sum of engine fuel consumption and motor equivalent fuel consumption. The method includes a step of allocating a minimum engine torque value of the equivalent fuel consumption compared to engine torque as an initial engine torque distribution amount in the case of an acceleration situation.

Description

A method and apparatus for controlling a mild hybrid system TECHNICAL FIELD

The present invention relates to a method and apparatus for controlling a mild hybrid system, and more particularly, to a method and apparatus for controlling a mild hybrid system capable of preventing frequent irregular changes in a torque distribution amount while having a minimum fuel consumption.

Increasing oil prices and increasing social interest in the environment are pushing the automobile industry to improve fuel efficiency and develop eco-friendly vehicles, and mild hybrid systems are being developed to satisfy this.

The mild hybrid system precisely controls the inverter and motor based on the current measured through the motor, the voltage battery that charges and provides the voltage power, the inverter that converts the voltage between the motor and the voltage battery, and the current sensor. It includes a control device and the like.

1 shows various positions of motors provided in a mild hybrid system.

In the mild hybrid system, as shown in FIG. 1, various methods such as P0, P1, P2, P3, and P4 are classified according to the position where the motor is provided. This conventional mild hybrid system drives a motor through the following operation control.

That is, the control device of the conventional mild hybrid system determines the driver's required torque during acceleration, then determines the optimal torque distribution amount for generating power required for driving, and then determines the engine and motor according to the determined torque distribution amount. Works. At this time, a combination of the torque distribution amount of the engine and the motor is determined to enable the output of the target driving torque required through the minimum fuel consumption.

However, the conventional mild hybrid system has a problem in that the change in the operating point, that is, the starting point of operation, frequently and irregularly occurs.

In order to solve the problems of the prior art, an object of the present invention is to provide a method and apparatus for controlling a mild hybrid system capable of preventing frequent irregular changes in torque distribution while having a minimum fuel consumption.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The control method of the mild hybrid system according to an embodiment of the present invention for solving the above problems is a control method of a mild hybrid system using equivalent fuel consumption, which is the sum of engine fuel consumption and motor equivalent fuel consumption. And allocating a minimum engine torque value among the equivalent fuel consumption compared to the engine torque as an initial engine torque distribution amount.

In the control method of the mild hybrid system according to an embodiment of the present invention, when the minimum engine torque value is less than the driver's required torque in the acceleration situation, a deficit for the driver's required torque is allocated as the motor torque distribution amount, but the motor generator It may further include a step of controlling to fill the corresponding deficit by operating as an auxiliary.

In the control method of the mild hybrid system according to an embodiment of the present invention, when the minimum engine torque value is greater than the driver's required torque in the acceleration situation, the motor generator operates for power generation according to the surplus of the driver's required torque to charge the battery. It may further include the step of controlling to be.

The control method of the mild hybrid system according to an embodiment of the present invention may further include the step of allocating the driver required torque as an initial engine torque distribution amount if the minimum engine torque value is the same as the driver required torque in the acceleration situation.

In the control method of the mild hybrid system according to an embodiment of the present invention, when the motor generator is operated for torque assistance in the acceleration situation, the increment obtained by dividing the initial motor torque distribution amount by the total amount of motor torque distribution provided is the engine torque according to time. As added to, the step of gradually reducing the amount of motor torque distribution may be further included.

The control method of the mild hybrid system according to an embodiment of the present invention may further include the step of allocating a maximum value to the total provision time of motor torque distribution when the accelerator pedal is released.

The control method of the mild hybrid system according to an embodiment of the present invention may further include determining an acceleration situation when the rate of change of the driver torque per hour is greater than the first reference value.

In the control method of the mild hybrid system according to an embodiment of the present invention, when the rate of change of the driver's torque per hour is less than a first reference value, and the charging value of the battery is less than the second reference value, determining that the battery needs to be charged. It may contain more.

The control method of the mild hybrid system according to an embodiment of the present invention controls the motor generator to operate for power generation by allocating the driver's required torque and the motor torque for charging the battery to be included in the engine torque distribution amount when charging is necessary. It may further include the step of.

The control method of the mild hybrid system according to an embodiment of the present invention further includes determining a neutral mode situation when the rate of change of the driver's torque per hour is less than the first reference value and the charging value of the battery is greater than the second reference value. I can.

The control method of the mild hybrid system according to an embodiment of the present invention may further include determining a driver's required torque as an engine torque distribution amount in the neutral mode situation.

A control device for a mild hybrid system according to an embodiment of the present invention is a control device for a mild hybrid system using equivalent fuel consumption, which is the sum of engine fuel consumption and motor equivalent fuel consumption. In the case of acceleration, among equivalent fuel consumption compared to engine torque The minimum engine torque value is allocated as the initial engine torque distribution amount.

In the control device of the mild hybrid system according to an embodiment of the present invention, when the minimum engine torque value is less than the driver's required torque in the acceleration situation, a deficit for the driver's required torque is allocated as the motor torque distribution amount, but the motor generator It can act as an auxiliary and control it to fill that deficit.

In the control device of the mild hybrid system according to an embodiment of the present invention, when the motor generator is operated for torque assistance in the acceleration situation, the increment obtained by dividing the initial motor torque distribution amount by the total amount of motor torque distribution provided is the engine torque according to time. As it is added to, the amount of motor torque distribution can be gradually reduced.

The control apparatus of the mild hybrid system according to an embodiment of the present invention may allocate a maximum value to the total provision time of motor torque distribution when the accelerator pedal is depressurized.

The control apparatus of the mild hybrid system according to an embodiment of the present invention may determine an acceleration situation when the rate of change of the driver's torque per hour is greater than a first reference value.

The control device of the mild hybrid system according to an embodiment of the present invention performs driver required torque and battery charging when the charging value of the battery is smaller than the second reference value when the rate of change of the driver torque per hour is less than the first reference value. It is possible to control the motor generator to operate for power generation by allocating the required motor torque to be included in the engine torque distribution amount.

The control device of the mild hybrid system according to an embodiment of the present invention calculates that when the rate of change of the driver's torque per hour is less than the first reference value and the charge value of the battery is greater than the second reference value, the driver demanded torque is allocated to the engine torque. Can be assigned as

The present invention configured as described above allocates the minimum engine torque value among the equivalent fuel consumption compared to the engine torque as the initial engine torque distribution amount, that is, the engine torque distribution amount at the starting point of operation, so that the minimum fuel consumption amount but the torque distribution amount It has the advantage of preventing frequent changes.

In addition, according to the present invention, when the motor generator is operated as a torque auxiliary in an acceleration situation, since the engine torque and the motor torque are constantly changed according to the increment, there is an advantage of preventing irregular changes in the torque distribution amount.

1 shows various positions of motors provided in a mild hybrid system.
2 shows the configuration of a mild hybrid system according to an embodiment of the present invention.
3 is a flowchart of a control operation performed in a mild hybrid system according to an embodiment of the present invention.
4 is a graph of engine fuel consumption, motor equivalent fuel consumption, and equivalent fuel consumption used in torque distribution (S12) of a control operation performed in a mild hybrid system according to an embodiment of the present invention.
5 is a diagram of the driver's required torque, engine torque, and motor torque when the motor generator 20 operates as a torque assist motor during torque distribution (S12) of the control operation performed in the mild hybrid system according to an embodiment of the present invention. Show change graph

The above objects and means of the present invention and the effects thereof will become more apparent through the following detailed description in relation to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains can facilitate the technical idea of the present invention. It will be possible to do it. In addition, in describing the present invention, when it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

The terms used in this specification are for describing exemplary embodiments, and are not intended to limit the present invention. In the present specification, the singular form also includes the plural form in some cases, unless specifically stated in the phrase. In the present specification, terms such as "include", "include", "provision" or "have" do not exclude the presence or addition of one or more other elements other than the mentioned elements.

In the present specification, terms such as “or” and “at least one” may represent one of words listed together, or a combination of two or more. For example, “A or B” and “at least one of A and B” may include only one of A or B, and may include both A and B.

In this specification, the description following “for example” may not exactly match the information presented, such as the recited characteristics, variables, or values, and tolerances, measurement errors, limitations of measurement accuracy, and other commonly known factors. It should not be limited to the embodiments of the invention according to the various embodiments of the present invention to effects such as modifications including.

In the present specification, when a component is described as being'connected' or'connected' to another component, it may be directly connected or connected to the other component, but other components exist in the middle. It should be understood that it may be possible. On the other hand, when a component is referred to as being'directly connected' or'directly connected' to another component, it should be understood that there is no other component in the middle.

In the present specification, when a component is described as being'on' or'adjacent' of another component, it may be directly in contact with or connected to another component, but another component exists in the middle. It should be understood that it is possible. On the other hand, when a component is described as being'directly above' or'directly' of another component, it may be understood that there is no other component in the middle. Other expressions describing the relationship between components, for example,'between' and'directly,' can be interpreted as well.

In this specification, terms such as'first' and'second' may be used to describe various elements, but the corresponding elements should not be limited by the above terms. In addition, the terms above should not be interpreted as limiting the order of each component, and may be used for the purpose of distinguishing one component from another component. For example, the'first element' may be named'second element', and similarly, the'second element' may also be named'first element'.

Unless otherwise defined, all terms used in the present specification may be used as meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.

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

2 shows the configuration of a mild hybrid system according to an embodiment of the present invention.

In the mild hybrid system according to an embodiment of the present invention, as shown in FIG. 2, an engine 10, a motor generator 20, an inverter 30, a battery 40, and an electric control unit ; Hereinafter, referred to as “ECU”) 50 and a sensor unit 60 may be included.

The motor generator 20 is a configuration that is linked with the engine 10 by a belt, and is capable of operating as a torque auxiliary motor to assist power of the engine 10 and a generator capable of generating AC voltage. That is, when operating as a torque assist motor, the motor generator 20 may receive driving power through the inverter 30 to assist the power of the engine 10. In addition, when operating as a generator, the motor generator 20 may supply electric energy generated during vehicle braking to the battery 50.

The inverter 30 is a configuration for controlling electric energy entering and leaving the motor generator 20. That is, the inverter 30 converts the electric energy supplied from the battery 50 and supplies it to the motor generator 20, or converts the electric energy generated from the motor generator 2000 and supplies it to the battery 50. can do.

The battery 40 may play a role of supporting engine torque by storing electric energy regeneratively braking in the motor generator 20 in a vehicle deceleration situation and by supplying electrical energy to the motor generator 20 in a vehicle acceleration situation. . The battery 40 may include a low voltage battery and a high voltage battery, respectively. For example, the battery 40 may be formed of a supercapacitor module including a plurality of supercapacitors.

The high voltage battery and the low voltage battery have relatively different voltages from each other, and the high voltage battery provides a higher voltage than the low voltage battery. For example, a high voltage battery can provide 24V to 60V, and a voltage battery can provide 6V to 24V. In addition, the high voltage battery and the low voltage battery may transmit their current state information to the ECU 50. In this case, the current state information may be information on a provided voltage, a provided current, and an amount of charge.

In particular, the mild hybrid system according to an embodiment of the present invention may have an Idle Stop & Go (ISG) function in which the engine is automatically turned off when the vehicle is stopped for a long time and then turns on again when the vehicle starts. That is, when the charging voltage of the high voltage battery is greater than or equal to the reference voltage during idle stop, the voltage charged in the high voltage battery may be supplied to the low voltage battery through the converter.

The ECU 50 serves to control each component of the mild hybrid system based on sensor information detected through the various sensor units 60 mounted on the vehicle.

Hereinafter, a control operation performed in the mild hybrid system according to an embodiment of the present invention will be described.

3 is a flowchart of a control operation performed in a mild hybrid system according to an embodiment of the present invention.

The ECU 50 may perform the control operations of S11 to S15, as shown in FIG. 3.

First, it is determined whether there is an acceleration situation (S11). That is, when the rate of change of the driver's torque per hour (Δ driver demanded torque/Δt) is greater than the first reference value TH1, it may be determined as the acceleration situation, and when it is less than or less than that, it may be determined that the acceleration situation is not. In this case, the first reference value TH1 may be preset or changed in real time.

Thereafter, as a result of the determination of S11, in the case of an acceleration situation, it is possible to determine the distribution of the engine torque and the motor torque (S12).

FIG. 4 is a graph of engine fuel consumption, motor equivalent fuel consumption, and equivalent fuel consumption used in torque distribution (S12) of a control operation performed in a mild hybrid system according to an embodiment of the present invention.

For the torque distribution of S12, engine fuel consumption ( m ), motor consumption equivalent fuel amount (pⅹ SOC ) (however, SOC is electrical power, which is the amount of change in electrical energy, p is the conversion factor for converting SOC into fuel consumption) , And data on the equivalent fuel consumption (H), which is the sum of these, can be used. At this time, engine fuel consumption compared to torque ( m ), motor consumption equivalent fuel amount (px SOC ), and equivalent fuel consumption (H) may be shown as shown in FIG. 4, and their data may be measured and stored in the system.

When the driver's required torque according to the acceleration situation occurs, torque distribution is determined in various ways according to the area of the engine torque value corresponding to the minimum point (minimum point) (M) among the data of the equivalent fuel consumption compared to the engine torque shown in FIG. I can.

That is, if the engine torque value of the minimum point (M) is smaller than the driver's required torque, the engine torque value of the minimum point (M) is determined as the initial engine torque distribution amount (optimum torque), but the driver according to the initial engine torque distribution amount By determining the shortfall of the required torque as the initial motor torque distribution amount, it is possible to assist the engine torque through the motor torque. In this case, the remainder of the initial engine torque distribution subtracted from the driver's required torque has a value less than 0, and the shortfall is determined as an initial motor torque distribution amount for assisting the engine power, and accordingly, the motor generator 20 It can function as a torque assist motor.

In addition, if the engine torque value of the minimum point (M) is larger than the driver's required torque, the engine torque value of the minimum point (M) is determined as the initial engine torque distribution amount (optimum torque), but the driver according to the initial engine torque distribution amount The surplus of the required torque may be determined for power generation of the motor generator 20 for charging the battery 40. In this case, the remainder of the initial engine torque distribution minus the driver's required torque has a value greater than 0, and the corresponding excess is determined for power generation of the motor generator 20, and accordingly, the motor generator 20 functions as a generator. can do.

In addition, when the engine torque value of the minimum point M is the same as the driver's required torque, the engine torque value of the minimum point M, which is the driver's required torque, may be determined as the initial engine torque distribution amount (optimum torque). In this case, since the remainder of the initial engine torque distribution subtracted from the driver's required torque is 0, the motor generator 20 does not operate and does not function as a torque auxiliary motor or for power generation.

The present invention has a constant starting point by setting the initial engine torque distribution amount to the engine torque value of the minimum point (M) of the equivalent fuel consumption compared to the engine torque, and accordingly, the problem of the prior art in which the change in the starting point frequently occurred. Can be solved.

5 is a diagram illustrating a driver's required torque, an engine torque, and a motor torque when the motor generator 20 operates as a torque auxiliary motor during torque distribution (S12) of the control operation performed in the mild hybrid system according to an embodiment of the present invention. Show change graph

Meanwhile, when the motor generator 20 operates as a torque auxiliary motor after the initial motor torque distribution according to S12, it may be controlled as follows (hereinafter, referred to as “torque assist control”). That is, as shown in FIG. 5, after the initial motor torque distribution, an incremental increment is added to the engine torque over time, and accordingly, the motor torque distribution amount can be gradually reduced by the corresponding increment. In this case, the increment may be a value obtained by dividing the initial motor torque distribution amount by the total amount of motor torque distribution providing time. However, the total provision time for distribution of motor torque is a time for the motor generator 20 to function as a torque auxiliary motor in the current acceleration situation, and may be preset or changed in real time.

Based on the initial motor torque distribution determined at the time of entering the acceleration situation, the motor generator 20 maintains the torque assistance for a certain period of time (the total amount of motor torque distribution provided), and the release time of the torque assistance is the incremental motor It can be calculated according to the ramp waveform of the torque. That is, the current motor torque may be a value obtained by subtracting a corresponding increment from the previous motor torque. Accordingly, after the predetermined time elapses, the current motor torque value becomes 0, and the torque assist control is released. In this case, the motor generator 20 does not function as a torque auxiliary motor until an acceleration situation occurs again.

That is, in the present invention, when the motor generator is operated for torque assistance in an acceleration situation, the engine torque and the motor torque are constantly changed according to increments, and thus the problem of the prior art in which the change in the torque distribution amount is irregular can be solved.

However, when the accelerator pedal is depressurized, or when the driver's required torque is less than the product of the motor torque distribution and the pulley ratio (i.e., the value converted from the torque currently controlled by the motor into the crankshaft value) When the torque is smaller than the required torque value, a situation in which the torque assist control must be released may additionally occur, such as a situation in which the pressurization amount of the accelerator pedal is reduced). In this case, not only should the engine torque supply be released so that the engine 10 no longer supplies power, but also the torque assist function of the motor generator 20 should be released. In particular, by assigning a maximum value (a value close to infinity) to the total provision time of the motor torque distribution and setting the increment close to 0, the function of the torque assistance of the motor generator 20 can be immediately released. In this case, when the accelerator pedal is depressurized, the driver does not press the accelerator pedal any more, and corresponding information may be transmitted to the ECU 50 through the sensor unit 60.

Next, when it is determined that the acceleration situation is not in S11, it may be determined as two situations according to the charging state of the battery 40 (S13). That is, it may be determined whether the charging value of the battery 40 is smaller than the second reference value TH2. In this case, the second reference value TH2 may be preset or changed in real time.

When the battery is in the LOW charging state, that is, the charging value of the battery 40 is less than the second reference value TH2, it may be determined as a situation in which the battery 40 needs to be charged. In this case, the motor generator 20 functions as a generator to charge the battery 40 (S14). To this end, in S140, it may be determined that the driver's required torque and the motor torque for charging the battery are included in the initial engine torque distribution amount. Accordingly, the remainder by subtracting the driver's required torque from the initial engine torque distribution amount has a value greater than 0, and a corresponding surplus amount is determined for power generation of the motor generator 20.

When the battery is in a HIGH charging state, that is, the charging value of the battery 40 is greater than or equal to the second reference value TH2, it may be determined as a neutral mode state. In this case, the driver's required torque can be determined as an initial engine torque distribution amount. Accordingly, since the remainder of the initial engine torque distribution subtracted from the driver's required torque is 0, the motor generator 20 does not operate and does not function as a torque auxiliary motor or for power generation.

In the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention is not limited to the described embodiments, and should be determined by the scope of the claims to be described later and those equivalent to the scope of the claims.

10: engine 20: motor generator
30: inverter 40: battery
50: ECU 60: sensor unit

Claims (16)

As a control method of a mild hybrid system using equivalent fuel consumption, which is the sum of engine fuel consumption and motor equivalent fuel consumption,
In the case of an acceleration situation, the control method of a mild hybrid system, comprising the step of allocating a minimum engine torque value among the equivalent fuel consumption compared to the engine torque as an initial engine torque distribution amount. The method of claim 1,
If the minimum engine torque value is less than the driver's required torque in the acceleration situation, the deficit for the driver's torque is allocated as the motor torque distribution amount, but a further step of controlling the motor generator to operate to supplement the torque to fill the deficit is further performed. Control method of a mild hybrid system comprising a. The method of claim 1,
When the minimum engine torque value is greater than the driver's required torque in the acceleration situation, the method further comprises controlling the motor generator to operate for power generation and charge the battery according to an excess of the driver's required torque. Control method. The method of claim 1,
And if the minimum engine torque value is equal to the driver's required torque in the acceleration situation, allocating the driver's required torque as an initial engine torque distribution amount. The method of claim 2,
In the above acceleration situation, when the motor generator is operated as a torque aid, the increment of the initial motor torque distribution divided by the total amount of motor torque distribution provision time is added to the engine torque over time, thereby gradually reducing the motor torque distribution amount. Control method of a mild hybrid system, characterized in that. The method of claim 5,
When the pressurization of the accelerator pedal is released, allocating a maximum value to the total provision time for distributing the motor torque, the method of controlling a mild hybrid system, further comprising. The method of claim 1,
The control method of a mild hybrid system, further comprising determining an acceleration situation when the rate of change of the driver's torque per hour is greater than the first reference value. The method of claim 7,
When the rate of change of the driver's torque per hour is less than the first reference value, the charging value of the battery is less than the second reference value, further comprising the step of determining that the battery needs charging,
Control of a mild hybrid system, further comprising the step of controlling the motor generator to operate for power generation by allocating the driver's required torque and the motor torque for charging the battery to be included in the engine torque distribution amount in the case of a need for charging situation Way. The method of claim 7,
If the rate of change of the driver's torque per hour is less than the first reference value, the charging value of the battery is greater than the second reference value, further comprising the step of determining a neutral mode situation,
In the case of the neutral mode situation, the control method of a mild hybrid system, further comprising the step of determining the driver's required torque as an engine torque distribution amount. As a control device for a mild hybrid system that uses equivalent fuel consumption, which is the sum of engine fuel consumption and motor equivalent fuel consumption,
In the case of an acceleration situation, the control device of a mild hybrid system, characterized in that the minimum engine torque value among the equivalent fuel consumption compared to the engine torque is allocated as an initial engine torque distribution amount. The method of claim 10,
In the acceleration situation, when the minimum engine torque value is less than the driver's required torque, a deficit for the driver's torque is allocated as the motor torque distribution amount, but the motor generator operates as a torque subsidiary to control to fill the deficit. The control device of the mild hybrid system. The method of claim 11,
When the motor generator is operated as a torque aid in the acceleration situation, the amount of motor torque distribution is gradually reduced as an increment obtained by dividing the initial motor torque distribution amount by the total amount of motor torque distribution provision time is added to the engine torque over time. The control unit of the mild hybrid system. The method of claim 12,
When the pressurization of the accelerator pedal is released, a maximum value is assigned to a total provision time of motor torque distribution. The method of claim 12,
The control apparatus of a mild hybrid system, characterized in that when the rate of change of the driver torque per hour is greater than a first reference value, an acceleration situation is determined. The method of claim 12,
When the rate of change of the driver torque per hour is less than the first reference value and the charge value of the battery is less than the second reference value, the driver required torque and the motor torque for charging the battery are allocated to be included in the engine torque distribution amount, and the motor generator Control device of a mild hybrid system, characterized in that for controlling to operate for power generation. The method of claim 11,
When the rate of change of the driver torque per hour is less than a first reference value and the charge value of the battery is greater than a second reference value, the driver required torque is allocated as an engine torque distribution amount.

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