CN109677270B - Motor braking energy recovery method and device - Google Patents
Motor braking energy recovery method and device Download PDFInfo
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- CN109677270B CN109677270B CN201811571180.3A CN201811571180A CN109677270B CN 109677270 B CN109677270 B CN 109677270B CN 201811571180 A CN201811571180 A CN 201811571180A CN 109677270 B CN109677270 B CN 109677270B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L7/00—Electrodynamic brake systems for vehicles in general
- B60L7/10—Dynamic electric regenerative braking
- B60L7/18—Controlling the braking effect
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Abstract
The application provides a motor braking energy recovery method and device, and the scheme comprises the following steps: when braking starts, obtaining a temperature value of a spiral bevel gear temperature value, calculating to obtain tooth surface friction loss power of the spiral bevel gear according to the current rotating speed and the calculated torque of the input end of a main speed reducer, then predicting a tooth surface instantaneous temperature rise value of a meshing part between tooth surfaces of the spiral bevel gear according to the tooth surface friction loss power, the current rotating speed and the calculated torque of the spiral bevel gear based on a third preset MAP, and controlling a braking system to reduce the electric braking required torque when the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is larger than a preset critical temperature value, so that the spiral bevel gear temperature value is kept lower than the preset critical temperature value during braking.
Description
Technical Field
The invention relates to the technical field of automobiles, in particular to a motor braking energy recovery method and a device for recovering braking energy of a motor by adjusting electric braking required torque in a braking process.
Background
The spiral bevel gear is a transmission part capable of realizing stable transmission and low-noise transmission, has the advantages of high transmission efficiency, stable transmission ratio, large overlap coefficient, high bearing capacity, stable and smooth transmission, reliable work, compact structure and the like, and is frequently applied to a braking system of a vehicle.
In the process of re-braking, the spiral bevel gear performs reverse transmission, the sliding friction between tooth surfaces of the spiral bevel gear is larger during the reverse transmission than that during the forward transmission, and the pressure between the tooth surfaces of a main reducer of a drive axle is large, so that the instantaneous temperature rise of relative sliding at the tooth surface meshing part and the temperature of the gear exceeds the critical temperature, an oil film is damaged, the friction is further intensified, and the tooth surface is easily damaged due to failure.
Disclosure of Invention
In view of the above, embodiments of the present invention provide a method and an apparatus for recovering braking energy of a motor, so as to prevent an oil film of a spiral bevel gear from being damaged during braking.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a method of recovering braking energy from an electric machine, comprising:
when braking starts, acquiring a temperature value of a spiral bevel gear in a braking system;
acquiring the current rotating speed of the input end of a main speed reducer in the braking system;
acquiring a calculated torque at the input end of the main speed reducer, wherein the calculated torque is matched with an electric braking demand torque in the current braking process;
determining the tooth surface friction loss power of the spiral bevel gear matched with the current rotating speed and the calculated torque based on a first preset MAP, and recording the tooth surface friction loss power as a power loss value, wherein the power loss value corresponding to the spiral bevel gear under each current rotating speed and calculated torque is stored in the first preset MAP;
determining a preset critical temperature value matched with the current rotating speed and the calculated torque based on a second preset MAP, wherein the second preset MAP stores corresponding preset critical temperature values at each current rotating speed and each calculated torque;
determining tooth surface instantaneous temperature rise values of the meshing positions between the tooth surfaces of the spiral bevel gear matched with the power loss value, the current rotating speed and the calculated torque based on a third preset MAP, wherein the tooth surface instantaneous temperature rise values corresponding to the current rotating speed, the calculated torque and the power loss value are stored in the third preset MAP;
judging whether the sum of the temperature value of the spiral bevel gear and the instantaneous temperature rise value is greater than the preset critical temperature value, and reducing the electric braking required torque when the judgment result is yes, and returning to the step: and acquiring the calculated torque at the input end of the main speed reducer.
Preferably, in the above method for recovering braking energy of an electric machine, the reducing the electric braking demand torque includes:
and reducing the electric braking required torque according to a preset step length or a preset proportion.
Preferably, in the method for recovering braking energy of an electric machine, the reducing the electric braking demand torque according to a preset step length or a preset ratio includes:
recording the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value as a first predicted temperature;
calculating the difference value between the first predicted temperature and the preset critical temperature value;
acquiring a target step length or a target proportion matched with the difference value of the first predicted temperature and the preset critical temperature value;
the electric brake demand torque is reduced according to a target step size or a target proportion.
Preferably, in the method for recovering braking energy of an electric motor, the obtaining a temperature value of a spiral bevel gear in a braking system includes:
and acquiring a gear oil temperature value of the spiral bevel gear, and taking the gear oil temperature value as the spiral bevel gear temperature value.
Preferably, in the method for recovering braking energy of an electric machine, before determining a preset critical temperature value matching the current rotation speed and the calculated torque based on a second preset MAP, the method further includes:
counting the aging degree T of the gear oil according to a formula T-a 1-TP 1+ a 2-TP 2+ · + an-TPn;
calibrating each preset critical temperature value in the second preset MAP according to a critical value calibration coefficient corresponding to the aging degree T, wherein each aging degree T is matched with one preset critical value calibration coefficient;
wherein the TP1 is the total duration of gear oil at the P1 temperature;
the a1 is a time length calibration coefficient corresponding to the temperature P1;
the TP2 is the total duration of gear oil at the P2 temperature;
the a2 is a time length calibration coefficient corresponding to the temperature P2;
the TPn is the total duration of the gear oil at the Pn temperature;
and the an is a time length calibration coefficient corresponding to the Pn temperature.
An electric machine braking energy recovery device comprising:
the gear temperature acquisition unit is used for acquiring a temperature value of the spiral bevel gear in the braking system when braking is started;
the main speed reducer input parameter acquisition unit is used for acquiring the current rotating speed of the input end of a main speed reducer in the braking system; acquiring a calculated torque at the input end of the main speed reducer, wherein the calculated torque is matched with an electric braking demand torque in the current braking process;
the power loss value calculating unit is used for determining the tooth surface friction loss power of the spiral bevel gear matched with the current rotating speed and the calculated torque based on a first preset MAP, and recording the tooth surface friction loss power as a power loss value, wherein the first preset MAP stores the corresponding power loss value of the spiral bevel gear under each current rotating speed and calculated torque;
the critical temperature calculation unit is used for determining a preset critical temperature value matched with the current rotating speed and the calculated torque based on a second preset MAP, and the second preset MAP stores corresponding preset critical temperature values under each current rotating speed and each calculated torque;
determining tooth surface instantaneous temperature rise values of the meshing positions between the tooth surfaces of the spiral bevel gear matched with the power loss value, the current rotating speed and the calculated torque based on a third preset MAP, wherein the tooth surface instantaneous temperature rise values corresponding to the current rotating speed, the calculated torque and the power loss value are stored in the third preset MAP;
and the torque recovery unit is used for judging whether the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is greater than the preset critical temperature value or not, outputting a control signal for reducing the electric brake required torque and triggering the main speed reducer input parameter acquisition unit when the judgment result is yes.
Preferably, in the above electric motor braking energy recovery device, when reducing the electric braking demand torque, the torque recovery unit is specifically configured to:
and reducing the electric braking required torque according to a preset step length or a preset proportion.
Preferably, in the above-mentioned motor braking energy recovery device, when the torque recovery unit reduces the electric braking required torque according to a preset step length or a preset ratio, the torque recovery unit is specifically configured to:
recording the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value as a first predicted temperature;
calculating the difference value between the first predicted temperature and the preset critical temperature value;
acquiring a target step length or a target proportion matched with the difference value of the first predicted temperature and the preset critical temperature value;
the electric brake demand torque is reduced according to a target step size or a target proportion.
Preferably, in the above-mentioned motor braking energy recovery device, the gear temperature acquisition unit is specifically configured to:
and acquiring a gear oil temperature value of the spiral bevel gear, and taking the gear oil temperature value as the spiral bevel gear temperature value.
Preferably, the motor braking energy recovery device further includes:
a critical value calibration unit for:
counting the aging degree T of the gear oil according to a formula T-a 1-TP 1+ a 2-TP 2+ · + an-TPn;
calibrating each preset critical temperature value in the second preset MAP according to a critical value calibration coefficient corresponding to the aging degree T, wherein each aging degree T is matched with one preset critical value calibration coefficient;
wherein the TP1 is the total duration of gear oil at the P1 temperature;
the a1 is a time length calibration coefficient corresponding to the temperature P1;
the TP2 is the total duration of gear oil at the P2 temperature;
the a2 is a time length calibration coefficient corresponding to the temperature P2;
the TPn is the total duration of the gear oil at the Pn temperature;
and the an is a time length calibration coefficient corresponding to the Pn temperature.
Based on the technical scheme, in the scheme provided by the embodiment of the invention, when braking is started, the temperature value of the spiral bevel gear temperature value is obtained, the tooth surface friction loss power of the spiral bevel gear is calculated according to the current rotating speed and the calculated torque of the input end of the main reducer, then the tooth surface instantaneous temperature rise value of the tooth surface at the meshing part between the tooth surfaces of the spiral bevel gear is predicted according to the tooth surface friction loss power, the current rotating speed and the calculated torque of the spiral bevel gear based on the third preset MAP, and when the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is greater than the preset critical temperature value, the braking system is controlled to reduce the electric braking required torque, so that the spiral bevel gear temperature value is kept lower than the preset critical temperature value during braking.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic flow chart illustrating a method for recovering braking energy of an electric machine according to an embodiment of the present disclosure;
FIG. 2 is a schematic flow chart illustrating a method for recovering braking energy from an electric machine according to another embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a braking energy recovery device of an electric machine according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
When a vehicle is braked, in order to prevent the oil film at the meshing position between the tooth surfaces of the spiral bevel gear from being damaged due to high temperature, so that the tooth surfaces are damaged due to failure, the application discloses a motor braking energy recovery method, and referring to fig. 1, the method comprises the following steps:
step S101: when braking starts, acquiring a temperature value of a spiral bevel gear in a braking system;
in the step, whether the vehicle starts to brake is judged by detecting a brake signal, and when the vehicle is detected to start to brake, a temperature value of the spiral bevel gear body is obtained, wherein the temperature value can be obtained by directly detecting the spiral bevel gear body by using a temperature sensor, or can be obtained by detecting the temperature of gear oil of the spiral bevel gear, and the temperature of the gear oil can approximately indicate the temperature of the spiral bevel gear body;
step S102: acquiring the current rotating speed of the input end of a main speed reducer in the braking system;
in the step, the current rotating speed of the input end of the main speed reducer can be obtained through a rotating speed sensor or in a mode of carrying out data acquisition on the main speed reducer;
step S103: acquiring the calculated torque at the input end of the main speed reducer;
when a braking system needs braking, the electric control unit can calculate an electric braking demand torque according to the treading depth of a brake pedal of the whole vehicle and the current states of a motor and a battery, the electric control unit can further calculate the torque at the input end of the main speed reducer according to the electric braking demand torque, the torque is recorded as a calculated torque, and the value of the calculated torque can be calculated based on the electric braking demand torque by adopting the prior art scheme;
step S104: determining the tooth surface friction loss power of the spiral bevel gear matched with the current rotating speed and the calculated torque based on a first preset MAP, and recording the power loss power as a power loss value;
in the technical scheme disclosed in the embodiment of the present application, a plurality of preset MAPs may be provided, and in this step, tooth surface friction loss power of the helical bevel gear this time is estimated based on a first preset MAP, where the first preset MAP stores mapping relationships between rotational speed at an input end of the main reducer and calculated torque at the input end and tooth surface friction loss power of the helical bevel gear, where the mapping relationships may be pre-established in the first preset MAP, and table lookup is performed on the first preset MAP according to the previous rotational speed and the calculated torque, so that tooth surface friction loss power of the helical bevel gear with the previous rotational speed matched with the calculated torque can be obtained;
the power loss value comprises power loss caused by bearing friction loss, oil churning loss, differential friction loss and the like, and the friction listed above has smaller loss in reverse transmission, so the power loss value approximately indicates tooth surface friction loss power in consideration of safety margin;
step S105: determining a preset critical temperature value matched with the current rotating speed and the calculated torque based on a second preset MAP;
when the current rotating speed and the calculated torque of the input end of the main reducer under different working conditions are different, the corresponding preset critical temperature values are different, the preset critical temperature values are used for representing the maximum bearing temperature of an oil film at the meshing position between the tooth surfaces of the spiral bevel gear allowed by a system, when the temperature of the meshing position between the tooth surfaces is larger than the critical temperature values, the oil film is at risk of being damaged, and the maximum bearing temperature of the oil film is different at the input end of the main reducer under different working conditions of the current rotating speed and the calculated torque, namely the critical temperature values are different;
according to the technical scheme disclosed by the embodiment of the application, the second preset MAP is used for storing the corresponding critical temperature values of the oil film under the working conditions of different current rotating speeds and calculated torques at the input end of the main reducer, and on the premise of obtaining the current rotating speed and the calculated torques at the input end of the main reducer, the second preset MAP is subjected to table lookup to obtain the critical temperature value matched with the previous rotating speed and the calculated torques; and, the data and mapping relation in the said second presets MAP are already configured;
step S106: determining a tooth surface instantaneous temperature rise value of a meshing part between tooth surfaces of the spiral bevel gear matched with the power loss value, the current rotating speed and the calculated torque based on a third preset MAP;
when the power loss value, the current rotating speed and the tooth surface instantaneous temperature rise value corresponding to the calculated torque under different working conditions are different, and the tooth surface instantaneous temperature rise value is used for representing the temperature rise of the meshing part between the tooth surfaces in unit time when a braking system is braked;
according to the technical scheme disclosed by the embodiment of the application, under the working condition that different power loss values, current rotating speeds and calculated torques correspond to one another are stored in a third preset MAP, the instantaneous temperature rise value of the tooth surface is obtained by looking up the table of the third preset MAP on the premise that the power loss value, the current rotating speeds and the calculated torques are obtained; and, the data and mapping relation in the third preset MAP are already configured;
step S107: judging whether the sum of the temperature value of the spiral bevel gear and the temperature rise value is larger than the preset critical temperature value, if so, executing a step S108, and if not, executing a step S109: controlling a braking system to brake;
in this step, if the sum of the temperature value of the spiral bevel gear and the instantaneous temperature rise value is greater than the preset critical temperature value, it indicates that the temperature of the tooth surface of the spiral bevel gear at the next moment is greater than the preset critical temperature value after the current braking required torque of the braking system is braked, and therefore, in order to prevent the situation, the control system is required to reduce the electric braking required torque; if the judgment result is negative, controlling the braking system to brake by the current electric braking demand torque;
step S108: reducing the electric braking demand torque, and returning to the step S103;
step S109: and controlling the brake system to brake.
It can be seen from the technical solutions disclosed in the embodiments of the present application that, in the technical solutions disclosed in the embodiments of the present application, when braking starts, a temperature value of a spiral bevel gear temperature value is obtained, a tooth surface friction loss power of the spiral bevel gear is calculated according to a current rotational speed and a calculated torque of an input end of a main reducer, then an instantaneous tooth surface temperature rise value at a tooth surface meshing position between tooth surfaces of the spiral bevel gear is predicted according to the tooth surface friction loss power, the current rotational speed and the calculated torque of the spiral bevel gear based on a third preset MAP, and when a sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is greater than the preset critical temperature value, a braking system is controlled to reduce the electric braking demand torque, so that the spiral bevel gear temperature value is kept lower than the preset critical temperature value.
Specifically, in the technical scheme disclosed in the above-mentioned embodiment of the present application, when the electric brake demand torque is reduced, the electric brake demand torque may be reduced according to a preset compensation or a preset proportion, for example, the value of the electric brake demand torque reduced at each time is the same, or the proportion of the current electric brake demand torque occupied by the electric brake demand torque reduced at each time is the same.
In a technical solution disclosed in another embodiment of the present application, the amount of electric brake demand torque that is reduced each time may be adjusted according to a sum of a spiral bevel gear temperature value and the instantaneous temperature rise value and a difference between the preset critical temperature value and the instantaneous temperature rise value, for example, the larger the difference is, the larger the amount of electric brake demand torque that is reduced this time is, specifically, referring to fig. 2, in the foregoing method, reducing the electric brake demand torque according to a preset step length or a preset ratio may include:
step S201: recording the sum of the spiral bevel gear temperature value and the temperature rise value as a first predicted temperature;
step S202: calculating the difference value between the first predicted temperature and the preset critical temperature value;
step S203: acquiring a target step length or a target proportion matched with the difference value of the first predicted temperature and the preset critical temperature value;
specifically, the mapping relationship between the difference and the target step size or the target ratio may be stored in a fourth preset MAP, and the target step size or the target ratio matched with the difference may be obtained through a table look-up of the fourth preset MAP.
Step S204: the electric brake demand torque is reduced according to a target step size or a target proportion.
Further, when the temperature value of the spiral bevel gear in the braking system is obtained, in addition to directly measuring the temperature of the spiral bevel gear, the gear oil temperature value of the spiral bevel gear may also be obtained according to the gear oil temperature of the spiral bevel gear, because the gear oil temperature of the spiral bevel gear may approximately indicate the temperature of the spiral bevel gear body, and therefore, the gear oil temperature value may be directly used as the temperature value of the spiral bevel gear.
In the braking system, the longer the service time of the gear oil is, the more serious the gear oil is aged, and the severity of the gear oil aging is inconsistent at different temperatures, and after the gear oil is aged, the corresponding preset critical temperature value is also changed, so in the technical scheme disclosed in the embodiment of the present application, in order to ensure the reliability of the preset critical temperature value, the size of the preset critical temperature value may be calibrated according to the aging degree of the gear oil, specifically, in the method, before determining the preset critical temperature value matched with the current rotation speed and the calculated torque based on the second preset MAP, the method further includes:
counting the aging degree T of the gear oil according to a formula T-a 1-TP 1+ a 2-TP 2+ · + an-TPn;
calibrating each preset critical temperature value in the second preset MAP according to a critical value calibration coefficient corresponding to the aging degree T, wherein each aging degree T is matched with one preset critical value calibration coefficient;
wherein the TP1 is the total duration of gear oil at the P1 temperature;
the a1 is a time length calibration coefficient corresponding to the temperature P1;
the TP2 is the total duration of gear oil at the P2 temperature;
the a2 is a time length calibration coefficient corresponding to the temperature P2;
the TPn is the total duration of the gear oil at the Pn temperature;
and the an is a time length calibration coefficient corresponding to the Pn temperature.
Corresponding to the method, the present application also discloses a motor braking energy recovery device, and the specific working contents of each unit in the device please refer to the contents of the above method embodiment, and the following describes the motor braking energy recovery device provided by the embodiment of the present application, and the motor braking energy recovery device described below and the above described motor braking energy recovery method can be referred to correspondingly.
Referring to fig. 3, the motor braking energy recovery apparatus may include:
a gear temperature acquisition unit 100, corresponding to step S101 in the method, for acquiring a temperature value of the spiral bevel gear in the braking system when braking is started;
a main reducer input parameter acquisition unit 200, corresponding to steps S102-S103 in the above method, for acquiring the current rotation speed of the input end of the main reducer in the brake system; acquiring a calculated torque at the input end of the main speed reducer, wherein the calculated torque is matched with an electric braking demand torque in the current braking process;
a power loss value calculating unit 300, corresponding to step S104 in the above method, configured to determine, as a power loss value, tooth surface friction loss power of the spiral bevel gear that matches the current rotation speed and the calculated torque based on a first preset MAP, where power loss values corresponding to the spiral bevel gear at each current rotation speed and calculated torque are stored in the first preset MAP;
a critical temperature calculation unit 400, corresponding to steps S105-S106 of the method, for determining a preset critical temperature value matching the current rotation speed and the calculated torque based on a second preset MAP, in which preset critical temperature values corresponding to the respective current rotation speeds and calculated torques are stored; determining tooth surface instantaneous temperature rise values of the meshing positions between the tooth surfaces of the spiral bevel gear matched with the power loss value, the current rotating speed and the calculated torque based on a third preset MAP, wherein the tooth surface instantaneous temperature rise values corresponding to the current rotating speed, the calculated torque and the power loss value are stored in the third preset MAP;
and a torque recovery unit 500, corresponding to steps S107-S109 in the method, for determining whether a sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is greater than the preset critical temperature value, and when the determination result is yes, outputting a control signal for reducing the electric brake demand torque, and triggering a main reducer input parameter acquisition unit.
It can be seen from the technical solutions disclosed in the embodiments of the present application that, in the technical solutions disclosed in the embodiments of the present application, when braking starts, a temperature value of a spiral bevel gear temperature value is obtained, a tooth surface friction loss power of the spiral bevel gear is calculated according to a current rotational speed and a calculated torque of an input end of a main reducer, then an instantaneous tooth surface temperature rise value at a tooth surface meshing position between tooth surfaces of the spiral bevel gear is predicted according to the tooth surface friction loss power, the current rotational speed and the calculated torque of the spiral bevel gear based on a third preset MAP, and when a sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is greater than the preset critical temperature value, a braking system is controlled to reduce the electric braking demand torque, so that the spiral bevel gear temperature value is kept lower than the preset critical temperature value.
Corresponding to the above method, the torque recovery unit 500, when reducing the electric brake demand torque, is specifically configured to:
and reducing the electric braking required torque according to a preset step length or a preset proportion.
Corresponding to the above method, when the torque recovery unit 500 reduces the electric brake demand torque according to a preset step length or a preset ratio, the torque recovery unit is specifically configured to:
recording the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value as a first predicted temperature;
calculating the difference value between the first predicted temperature and the preset critical temperature value;
acquiring a target step length or a target proportion matched with the difference value of the first predicted temperature and the preset critical temperature value;
the electric brake demand torque is reduced according to a target step size or a target proportion.
Corresponding to the above method, the gear temperature acquisition unit 100 is specifically configured to:
and acquiring a gear oil temperature value of the spiral bevel gear, and taking the gear oil temperature value as the spiral bevel gear temperature value.
Corresponding to the method, the device may further include:
a critical value calibration unit for:
counting the aging degree T of the gear oil according to a formula T-a 1-TP 1+ a 2-TP 2+ · + an-TPn;
calibrating each preset critical temperature value in the second preset MAP according to a critical value calibration coefficient corresponding to the aging degree T, wherein each aging degree T is matched with one preset critical value calibration coefficient;
wherein the TP1 is the total duration of gear oil at the P1 temperature;
the a1 is a time length calibration coefficient corresponding to the temperature P1;
the TP2 is the total duration of gear oil at the P2 temperature;
the a2 is a time length calibration coefficient corresponding to the temperature P2;
the TPn is the total duration of the gear oil at the Pn temperature;
and the an is a time length calibration coefficient corresponding to the Pn temperature.
For convenience of description, the above system is described with the functions divided into various modules, which are described separately. Of course, the functionality of the various modules may be implemented in the same one or more software and/or hardware implementations as the present application.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for recovering braking energy of an electric machine, comprising:
when braking starts, acquiring a temperature value of a spiral bevel gear in a braking system;
acquiring the current rotating speed of the input end of a main speed reducer in the braking system;
acquiring a calculated torque at the input end of the main speed reducer, wherein the calculated torque is matched with an electric braking demand torque in the current braking process;
determining the tooth surface friction loss power of the spiral bevel gear matched with the current rotating speed and the calculated torque based on a first preset MAP, and recording the tooth surface friction loss power as a power loss value, wherein the power loss value corresponding to the spiral bevel gear under each current rotating speed and calculated torque is stored in the first preset MAP;
determining a preset critical temperature value matched with the current rotating speed and the calculated torque based on a second preset MAP, wherein the second preset MAP stores corresponding preset critical temperature values at each current rotating speed and each calculated torque;
determining tooth surface instantaneous temperature rise values of the meshing positions between the tooth surfaces of the spiral bevel gear matched with the power loss value, the current rotating speed and the calculated torque based on a third preset MAP, wherein the tooth surface instantaneous temperature rise values corresponding to the current rotating speed, the calculated torque and the power loss value are stored in the third preset MAP;
judging whether the sum of the temperature value of the spiral bevel gear and the instantaneous temperature rise value is greater than the preset critical temperature value, and reducing the electric braking required torque when the judgment result is yes, and returning to the step: and acquiring the calculated torque at the input end of the main speed reducer.
2. The motor braking energy recovery method of claim 1 wherein said reducing the electric braking demand torque comprises:
and reducing the electric braking required torque according to a preset step length or a preset proportion.
3. The motor braking energy recovery method of claim 2 wherein the reducing the electric braking demand torque in accordance with a preset step size or a preset ratio comprises:
recording the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value as a first predicted temperature;
calculating the difference value between the first predicted temperature and the preset critical temperature value;
acquiring a target step length or a target proportion matched with the difference value of the first predicted temperature and the preset critical temperature value;
the electric brake demand torque is reduced according to a target step size or a target proportion.
4. The motor braking energy recovery method of claim 1 wherein said obtaining a temperature value for a helical bevel gear in a braking system comprises:
and acquiring a gear oil temperature value of the spiral bevel gear, and taking the gear oil temperature value as the spiral bevel gear temperature value.
5. The motor braking energy recovery method of claim 1, wherein prior to determining the preset threshold temperature value matching the current speed and calculated torque based on the second preset MAP, further comprising:
counting the aging degree T of the gear oil according to a formula T-a 1-TP 1+ a 2-TP 2+ · + an-TPn;
calibrating each preset critical temperature value in the second preset MAP according to a critical value calibration coefficient corresponding to the aging degree T, wherein each aging degree T is matched with one preset critical value calibration coefficient;
wherein the TP1 is the total duration of gear oil at the P1 temperature;
the a1 is a time length calibration coefficient corresponding to the temperature P1;
the TP2 is the total duration of gear oil at the P2 temperature;
the a2 is a time length calibration coefficient corresponding to the temperature P2;
the TPn is the total duration of the gear oil at the Pn temperature;
and the an is a time length calibration coefficient corresponding to the Pn temperature.
6. An electric machine braking energy recovery device, comprising:
the gear temperature acquisition unit is used for acquiring a temperature value of the spiral bevel gear in the braking system when braking is started;
the main speed reducer input parameter acquisition unit is used for acquiring the current rotating speed of the input end of a main speed reducer in the braking system; acquiring a calculated torque at the input end of the main speed reducer, wherein the calculated torque is matched with an electric braking demand torque in the current braking process;
the power loss value calculating unit is used for determining the tooth surface friction loss power of the spiral bevel gear matched with the current rotating speed and the calculated torque based on a first preset MAP, and recording the tooth surface friction loss power as a power loss value, wherein the first preset MAP stores the corresponding power loss value of the spiral bevel gear under each current rotating speed and calculated torque;
the critical temperature calculation unit is used for determining a preset critical temperature value matched with the current rotating speed and the calculated torque based on a second preset MAP, and the second preset MAP stores corresponding preset critical temperature values under each current rotating speed and each calculated torque;
determining tooth surface instantaneous temperature rise values of the meshing positions between the tooth surfaces of the spiral bevel gear matched with the power loss value, the current rotating speed and the calculated torque based on a third preset MAP, wherein the tooth surface instantaneous temperature rise values corresponding to the current rotating speed, the calculated torque and the power loss value are stored in the third preset MAP;
and the torque recovery unit is used for judging whether the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value is greater than the preset critical temperature value or not, outputting a control signal for reducing the electric brake required torque and triggering the main speed reducer input parameter acquisition unit when the judgment result is yes.
7. The electric machine braking energy recovery device of claim 6, wherein the torque recovery unit, when reducing the electric braking demand torque, is specifically configured to:
and reducing the electric braking required torque according to a preset step length or a preset proportion.
8. The electric machine braking energy recovery device of claim 7, wherein the torque recovery unit, when reducing the electric braking demand torque according to a preset step length or a preset ratio, is specifically configured to:
recording the sum of the spiral bevel gear temperature value and the instantaneous temperature rise value as a first predicted temperature;
calculating the difference value between the first predicted temperature and the preset critical temperature value;
acquiring a target step length or a target proportion matched with the difference value of the first predicted temperature and the preset critical temperature value;
the electric brake demand torque is reduced according to a target step size or a target proportion.
9. The electric machine braking energy recovery device of claim 6, wherein the gear temperature collection unit is specifically configured to:
and acquiring a gear oil temperature value of the spiral bevel gear, and taking the gear oil temperature value as the spiral bevel gear temperature value.
10. The electric machine braking energy recovery device of claim 6, further comprising:
a critical value calibration unit for:
counting the aging degree T of the gear oil according to a formula T-a 1-TP 1+ a 2-TP 2+ · + an-TPn;
calibrating each preset critical temperature value in the second preset MAP according to a critical value calibration coefficient corresponding to the aging degree T, wherein each aging degree T is matched with one preset critical value calibration coefficient;
wherein the TP1 is the total duration of gear oil at the P1 temperature;
the a1 is a time length calibration coefficient corresponding to the temperature P1;
the TP2 is the total duration of gear oil at the P2 temperature;
the a2 is a time length calibration coefficient corresponding to the temperature P2;
the TPn is the total duration of the gear oil at the Pn temperature;
and the an is a time length calibration coefficient corresponding to the Pn temperature.
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