CN115817187B - Energy recovery method for hybrid vehicle - Google Patents

Abstract

The invention discloses an energy recovery method of a hybrid electric vehicle, and relates to the technical field of hybrid electric vehicles. The energy recovery method of the hybrid vehicle includes the steps of: when the hybrid vehicle runs in the electric-only mode, it is determined whether the driver is stepping on the brake or not when the driver is not stepping on the accelerator. When the driver does not step on the brake, the motor rotating speed is monitored, the motor rotating speed is divided into different stages from low to high in advance, different motor braking torques are set in each stage, and the braking torque of the motor is determined according to the real-time rotating speed of the motor so as to recover the braking energy of the motor. According to the energy recovery method of the hybrid power vehicle, different braking torques are controlled by the motor in a sectionalized mode according to the rotating speed of the motor, so that the braking torque is prevented from suddenly changing and is smoothly transited when the hybrid power vehicle recovers energy through motor braking, smoothness of the hybrid power vehicle is guaranteed, and the feeling of a driver is improved.

Description

Energy recovery method for hybrid vehicle

Technical Field

The present invention relates to the technical field of hybrid vehicle, and in particular to an energy recovery method for a hybrid vehicle.

Background technique

Hybrid vehicles can recover energy through motor braking when going downhill, and convert the recovered braking energy into electrical energy to save energy.

In the prior art, the energy recovery of hybrid vehicles is to query the MAP or set curve according to the vehicle speed or brake opening to recover energy, and the MAP or set curve is formulated based on the set slope. Therefore, the braking torque of the motor in the existing solution is relatively fixed and cannot be applied to all loads and slopes. In particular, vehicles without slope sensors are prone to speeding on large slopes while being suitable for small slopes; or, the vehicle is suitable for large slopes but slows down too fast on small slopes or flat roads.

Summary of the invention

The purpose of the present invention is to provide an energy recovery method for a hybrid vehicle, which is applicable regardless of whether a slope sensor is provided, to ensure that the braking torque of the hybrid vehicle does not change suddenly and transitions smoothly, thereby ensuring the ride comfort of the hybrid vehicle and improving the driver's experience.

To achieve this object, the present invention adopts the following technical solutions:

A method for recovering energy in a hybrid vehicle comprises the following steps:

When the hybrid vehicle is running in a pure electric mode, if the driver does not step on the accelerator, determining whether the driver has stepped on the brake;

When the driver does not step on the brakes, the motor speed is monitored and divided into different stages from low to high in advance. A different motor braking torque is set for each stage. The motor braking torque is determined according to the real-time motor speed to recover the motor's braking energy.

As an optional solution of the energy recovery method for a hybrid vehicle, when the motor speed is less than or equal to a first speed, controlling the motor to recover energy at a first set torque;

When the motor speed is greater than the first speed and less than or equal to the warning speed, the motor is controlled to perform energy recovery at a second set torque, where the second set torque is greater than the first set torque;

When the motor speed is greater than the warning speed, the motor is controlled to perform energy recovery at the maximum allowable torque.

As an optional scheme for the energy recovery method of a hybrid vehicle, when the motor speed exceeds the warning speed, the hybrid vehicle is controlled to switch from a pure electric mode to a hybrid mode, and brakes are performed jointly by engine-assisted braking and motor braking.

As an alternative solution to the energy recovery method of the hybrid vehicle, when braking is performed jointly by the engine auxiliary braking and the motor braking, the engine speed is lower than a set safety speed.

As an optional solution for the energy recovery method of hybrid vehicles, when the driver steps on the brakes, the brake opening is monitored and the brake opening is pre-divided into different stages from small to large. A different motor braking torque is set for each stage, and the motor braking torque is determined according to the real-time brake opening to recover the motor's braking energy.

As an optional solution of the energy recovery method for a hybrid vehicle, when the brake opening is less than or equal to the first opening, the motor is controlled to recover energy at a third set torque;

When the brake opening is greater than the first opening and less than or equal to the intermediate opening, the motor is controlled to perform energy recovery with a fourth set torque, and the fourth set torque is greater than the third set torque;

When the brake opening is greater than the intermediate opening and less than or equal to the maximum opening, the motor is controlled to perform energy recovery with a fifth set torque, and the fifth set torque is greater than the fourth set torque.

As an optional scheme for the energy recovery method of a hybrid vehicle, when the driver steps on the brakes, the motor speed is monitored while monitoring the brake opening. When the motor recovers energy with the third set torque, if the motor speed is greater than the first set speed, the hybrid vehicle is controlled to switch from a pure electric mode to a hybrid mode.

As an optional scheme for the energy recovery method of a hybrid vehicle, when the motor recovers energy with the fourth set torque, if the motor speed is greater than a second set speed, the hybrid vehicle is controlled to be converted from a pure electric mode to a hybrid mode, and the second set speed is less than the first set speed.

As an optional scheme for the energy recovery method of a hybrid vehicle, when the motor recovers energy with the fifth set torque, if the motor speed is greater than the third set speed, the hybrid vehicle is controlled to be converted from a pure electric mode to a hybrid mode, and the third set speed is less than the second set speed.

As an optional scheme for the energy recovery method of a hybrid vehicle, when the brake opening is greater than the maximum opening, the motor is controlled to recover energy with a sixth set torque, the sixth set torque is greater than the fifth set torque, and the sixth set torque is a maximum torque allowed by the motor; or, the hybrid vehicle is controlled to switch from a pure electric mode to a hybrid mode.

As an optional scheme for the energy recovery method of a hybrid vehicle, when the brake opening is greater than the maximum opening, if the motor speed is less than or equal to the engine idle speed, the pure electric mode is maintained and the motor is controlled to recover energy with the sixth set torque; if the motor speed is greater than the fourth set speed, the hybrid vehicle is controlled to switch from the pure electric mode to the hybrid mode, and the fourth set speed is less than the third set speed.

Beneficial effects of the present invention:

The energy recovery method of a hybrid vehicle provided by the present invention, when the hybrid vehicle is running in pure electric mode, controls the motor braking respectively according to whether the driver steps on the brake to recover energy. When the driver does not step on the brake, that is, when the hybrid vehicle is gliding, monitor the motor speed, divide the motor speed into different stages from low to high in advance, set different motor braking torques for each stage, and determine the motor braking torque according to the real-time motor speed to recover the braking energy of the motor. During the gliding process of the vehicle and the process of increasing vehicle speed, the motor speed continues to increase. The higher the motor speed, the greater the set motor braking torque. Therefore, the braking force is gradually increased in sections according to the real-time motor speed until the motor speed is stable or the motor speed is overspeeded and switched to the hybrid mode. The energy recovery method of a hybrid vehicle provided by the present invention controls the motor with different braking torques in sections according to the motor speed, so as to ensure that when the hybrid vehicle recovers energy through motor braking, the braking torque will not change suddenly, and the transition is smooth, thereby ensuring the smoothness of the hybrid vehicle and improving the driver's experience.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of an energy recovery method for a hybrid vehicle provided by an embodiment of the present invention;

FIG2 is a flow chart of an energy recovery method for a hybrid vehicle when the driver does not step on the brakes provided by an embodiment of the present invention;

FIG3 is a flow chart of a method for recovering energy of a hybrid vehicle when a driver steps on the brakes, provided in an embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

As shown in FIG1 , this embodiment provides an energy recovery method for a hybrid vehicle, comprising the following steps:

S10: When the hybrid vehicle is running in the pure electric mode, if the driver does not step on the accelerator, determine whether the driver has stepped on the brake.

Energy recovery and energy saving can only be achieved when the motor is braking. Therefore, when the battery is fully charged, hybrid vehicles give priority to using pure electric mode. Usually, during normal driving, the driver steps on the accelerator to ensure that the hybrid vehicle travels at a certain speed. When deceleration is required, the accelerator will be released. Therefore, the state in which the driver releases the accelerator is considered to be the need for deceleration. If the driver does not step on the accelerator, the hybrid vehicle includes two states: coasting and braking. Generally, if the driver immediately steps on the brake after releasing the accelerator, it means that the hybrid vehicle requires a large braking force; and if the driver does not step on the brake after releasing the accelerator, it means that the hybrid vehicle can reach the required speed by coasting at this time. The energy of motor braking can be recovered during coasting and braking. Therefore, this embodiment divides the energy of motor braking into two states: coasting and braking after the driver releases the accelerator. Therefore, it is necessary to judge whether the driver steps on the brake.

S20. When the driver does not step on the brake, the motor speed is monitored and the motor speed is pre-divided into different stages from low to high. A different motor braking torque is set for each stage. The motor braking torque is determined according to the real-time motor speed to recover the braking energy of the motor.

When the driver does not step on the brake, that is, when the hybrid vehicle is in a gliding state, the motor speed is monitored. The higher the speed of the hybrid vehicle, the higher the motor speed, and the maximum force provided. At this time, in order to slow down, the hybrid vehicle changes the direction of the motor to provide braking force. The higher the motor speed, the greater the required braking torque. By pre-dividing the motor speed from low to high, each section corresponds to a different motor braking torque, and the higher the motor speed, the greater the motor braking torque, so that the braking torque of the hybrid vehicle gradually increases with the gradual increase of the motor speed, ensuring that the braking torque of the hybrid vehicle will not change suddenly, and the transition is smooth, ensuring the smoothness of the hybrid vehicle, and improving the driver's experience.

As shown in FIG2 , specifically, when the driver does not step on the brake, the energy recovery method of the hybrid vehicle includes the following steps:

S21. When the motor speed is less than or equal to a first speed, control the motor to perform energy recovery at a first set torque.

The first speed is greater than the minimum speed of the motor. When the motor speed is less than or equal to the first speed, that is, the motor speed is low, it means that the hybrid vehicle is at a low speed. The first set torque is the braking torque set when the hybrid vehicle is in a normal working condition. The normal working condition here means that the hybrid vehicle is in a flat road gliding state. The first speed and the first set torque can be specifically set by those skilled in the art according to actual conditions.

S22: When the motor speed is greater than the first speed and less than or equal to the warning speed, the motor is controlled to recover energy at a second set torque, where the second set torque is greater than the first set torque.

Each motor is provided with a warning speed to prevent the motor from running at a high speed for a long time and reducing the service life of the motor. When the motor speed is greater than the first speed and less than or equal to the warning speed, it means that the motor speed is within the normal speed range, but greater than the first speed, which means that in order to reduce the speed of the hybrid vehicle at this time, the motor needs a braking torque greater than the first set torque, so the motor is controlled to recover energy at the second set torque.

S23: When the motor speed is greater than the warning speed, the motor is controlled to recover energy at the maximum allowable torque.

When the motor speed is greater than the warning speed, it means that the hybrid vehicle is at a high speed and the motor needs to recover energy at its maximum allowable torque. The maximum allowable torque of the motor is related to the current state of the motor, battery, gearbox and rear axle. Those skilled in the art can calculate it according to the actual situation. The specific calculation method is already in the prior art and will not be repeated here.

S24. When the motor speed exceeds the alarm speed, the hybrid vehicle is controlled to switch from the pure electric mode to the hybrid mode, and brakes are performed jointly by engine auxiliary braking and motor braking.

The alarm speed is greater than the warning speed. During the gliding process of the hybrid vehicle, if the motor speed continues to increase, when the motor speed exceeds the alarm speed, it means that the motor braking alone can no longer meet the braking needs of the hybrid vehicle. In order to ensure safety, the hybrid vehicle should be immediately controlled to switch to hybrid mode, and the vehicle should be braked by engine auxiliary braking and motor braking.

In order to ensure the safety of the engine, the engine speed is lower than the set safety speed when the engine auxiliary braking and motor braking are used together. When the motor speed exceeds the alarm speed, it automatically switches to the hybrid mode to ensure the safety of the motor, and when the engine auxiliary braking and motor braking are used together, the engine speed is kept lower than the set safety speed to ensure the safety of the engine, thereby ensuring the safety performance of the hybrid vehicle.

S30. When the driver steps on the brake, the brake opening is monitored and the brake opening is pre-divided into different stages from small to large. Different motor braking torques are set for each stage. The motor braking torque is determined according to the real-time brake opening to recover the motor's braking energy.

When the driver steps on the brakes and the hybrid vehicle is in a braking state, as the vehicle speed increases, the driver continuously increases the brake opening and controls the motor in sections with different braking torques according to the real-time brake opening. The greater the brake opening, the greater the motor braking torque, so as to achieve smooth braking of the hybrid vehicle.

Specifically, as shown in FIG3 , when the driver steps on the brake, the energy recovery method of the hybrid vehicle includes the following steps:

S31. When the brake opening is less than or equal to the first opening, the motor is controlled to perform energy recovery at a third set torque.

The first opening is greater than the minimum opening of the brake, but is still at a smaller opening. The motor brakes with a normal braking torque. The technical personnel in this field can set the specific value of the first opening according to actual conditions, and the technical personnel in this field can set the third set torque based on experience.

When the driver steps on the brake, the motor speed is monitored while monitoring the brake opening to prevent the motor speed from being too high and unable to meet the braking force requirements of the hybrid vehicle. When the motor recovers energy at the third set torque, if the motor speed is greater than the first set speed, the hybrid vehicle is controlled to switch from the pure electric mode to the hybrid mode.

When the motor speed is greater than the first set speed, it indicates that the braking force required by the hybrid vehicle cannot be met by the motor braking, and engine auxiliary braking and motor braking are required to brake together.

S32: When the brake opening is greater than the first opening and less than or equal to the intermediate opening, the motor is controlled to perform energy recovery with a fourth set torque, and the fourth set torque is greater than the third set torque.

The larger the brake opening, the greater the required braking torque. Therefore, as the brake opening increases, the braking torque of the motor is controlled in stages to gradually increase, thereby meeting the braking force required by the hybrid vehicle and increasing the smoothness of the hybrid vehicle's braking.

When the motor recovers energy with the fourth set torque, if the motor speed is greater than the second set speed, the hybrid vehicle is controlled to switch from the pure electric mode to the hybrid mode, and the second set speed is less than the first set speed.

It should be noted that, the greater the brake opening, the greater the required motor braking torque, and the lower the motor speed threshold for switching to hybrid power. Therefore, the second set speed is lower than the first set speed.

It should be noted that the intermediate opening here only refers to an opening that is greater than the first set opening and less than the maximum opening, and does not limit the specific value of the intermediate opening.

S33: When the brake opening is greater than the intermediate opening and less than or equal to the maximum opening, the motor is controlled to recover energy with a fifth set torque, and the fifth set torque is greater than the fourth set torque.

When the brake opening is between the intermediate opening and the maximum opening, the braking torque of the motor increases to a fifth set torque.

When the motor recovers energy at the fifth set torque, if the motor speed is greater than the third set speed, the hybrid vehicle is controlled to switch from the pure electric mode to the hybrid mode, and the third set speed is less than the second set speed.

S34. When the brake opening is greater than the maximum opening, control the motor to recover energy with a sixth set torque, the sixth set torque is greater than the fifth set torque, and the sixth set torque is the maximum torque allowed by the motor; or control the hybrid vehicle to switch from a pure electric mode to a hybrid mode.

When the brake opening is greater than the maximum opening, it is necessary to ensure that the engine does not stall. If the motor speed is less than or equal to the engine idle speed, the engine may stall. At this time, the pure electric mode is maintained and the motor is controlled to recover energy at the sixth set torque to prevent the engine from stalling.

When the brake opening is greater than the maximum opening, if the motor speed is greater than the fourth set speed, it means that the motor speed is at a relatively high speed and the engine will not be choked, then the hybrid vehicle is controlled to switch from pure electric mode to hybrid mode. The fourth set speed is less than the third set speed, and the larger the brake opening, the smaller the fourth set speed. Regarding the fourth set speed, those skilled in the art can set it specifically according to the maximum opening of the engine and the brake.

When the brake opening is greater than the maximum opening but the motor speed is low, it means that the vehicle speed has dropped to a very low level. To prevent the engine from stalling, the pure electric mode is maintained and the motor is controlled to recover energy at the sixth set torque, and the sixth set torque can be the maximum torque allowed by the motor.

When the hybrid vehicle switches to hybrid mode, the auxiliary braking of the engine and the motor braking are reasonably coordinated to ensure that the motor speed of the hybrid vehicle is lower than the set speed and the vehicle speed is lower than the set speed. The set speed is the motor speed of the hybrid vehicle when it is running normally, and the set speed is the speed of the hybrid vehicle when it is running normally.

The energy recovery method for a hybrid vehicle provided in this embodiment gradually increases the motor braking force according to different motor braking torques set in segments from low to high for the motor speed when the hybrid vehicle is coasting, until the motor speed stabilizes or the motor automatically switches to the hybrid mode due to overspeed. When the hybrid vehicle is braking, the motor braking force is gradually increased according to different motor braking torques set in segments from small to large for the brake opening. The larger the brake opening, the greater the motor braking torque, and the lower the motor speed threshold for switching to the hybrid mode. The energy recovery method for a hybrid vehicle provided in this embodiment controls the motor with different braking torques in segments according to the motor speed and the brake opening, ensuring that when the hybrid vehicle recovers energy through motor braking, the braking torque does not change suddenly and transitions smoothly, thereby ensuring the smoothness of the hybrid vehicle and improving the driver's experience.

The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there will be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims (7)

1. A method for recovering energy of a hybrid vehicle, comprising the following steps: When the hybrid vehicle is running in a pure electric mode, if the driver does not step on the accelerator, determining whether the driver has stepped on the brake; When the driver does not step on the brake, the motor speed is monitored and the motor speed is pre-divided into different stages from low to high. Different motor braking torques are set for each stage. The motor braking torque is determined according to the real-time motor speed to recover the motor braking energy. When the driver steps on the brake, the brake opening is monitored and the brake opening is pre-divided into different stages from small to large. Different motor braking torques are set for each stage. The motor braking torque is determined according to the real-time brake opening to recover the motor braking energy. When the brake opening is less than or equal to the first opening, controlling the motor to perform energy recovery at a third set torque; When the brake opening is greater than the first opening and less than or equal to the intermediate opening, the motor is controlled to perform energy recovery with a fourth set torque, and the fourth set torque is greater than the third set torque; When the brake opening is greater than the intermediate opening and less than or equal to the maximum opening, the motor is controlled to perform energy recovery at a fifth set torque, and the fifth set torque is greater than the fourth set torque; When the driver steps on the brake, the motor speed is monitored while the brake opening is monitored. When the motor recovers energy at the third set torque, if the motor speed is greater than the first set speed, the hybrid vehicle is controlled to switch from a pure electric mode to a hybrid mode. When the motor recovers energy with the fourth set torque, if the motor speed is greater than the second set speed, the hybrid vehicle is controlled to switch from a pure electric mode to a hybrid mode, and the second set speed is less than the first set speed. 2. The energy recovery method of a hybrid vehicle according to claim 1, characterized in that when the motor speed is less than or equal to the first speed, the motor is controlled to recover energy at a first set torque; When the motor speed is greater than the first speed and less than or equal to the warning speed, the motor is controlled to perform energy recovery at a second set torque, where the second set torque is greater than the first set torque; When the motor speed is greater than the warning speed, the motor is controlled to perform energy recovery at the maximum allowable torque. 3. The energy recovery method of a hybrid vehicle according to claim 2 is characterized in that when the motor speed exceeds the alarm speed, the hybrid vehicle is controlled to be converted from a pure electric mode to a hybrid power mode, and braking is performed jointly by engine-assisted braking and motor braking. 4 . The energy recovery method of a hybrid vehicle according to claim 3 , characterized in that when braking is performed jointly by the engine auxiliary braking and the motor braking, the engine speed is lower than a set safety speed. 5. The energy recovery method for a hybrid vehicle according to claim 1 is characterized in that when the motor recovers energy with the fifth set torque, if the motor speed is greater than the third set speed, the hybrid vehicle is controlled to be converted from a pure electric mode to a hybrid mode, and the third set speed is less than the second set speed. 6. The energy recovery method of a hybrid vehicle according to claim 5 is characterized in that when the brake opening is greater than the maximum opening, the motor is controlled to recover energy with a sixth set torque, the sixth set torque is greater than the fifth set torque, and the sixth set torque is at most the maximum torque allowed by the motor; or, the hybrid vehicle is controlled to switch from a pure electric mode to a hybrid mode. 7. The energy recovery method for a hybrid vehicle according to claim 6 is characterized in that when the brake opening is greater than the maximum opening, if the motor speed is less than or equal to the engine idle speed, the pure electric mode is maintained and the motor is controlled to recover energy with the sixth set torque; if the motor speed is greater than the fourth set speed, the hybrid vehicle is controlled to switch from the pure electric mode to the hybrid mode, and the fourth set speed is less than the third set speed.