CN109733470B - Multi-mode energy management method for EPS (electric power storage) composite power supply of heavy commercial vehicle - Google Patents
Multi-mode energy management method for EPS (electric power storage) composite power supply of heavy commercial vehicle Download PDFInfo
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Abstract
The invention belongs to the field of energy management of vehicle-mounted composite power supplies, and particularly relates to a multi-mode energy management method of an EPS composite power supply of a heavy-duty commercial vehicle. The invention can distribute the output power of the generator and the charge-discharge power of the super capacitor in real time, and can enable the generator to work in the optimal working interval as far as possible while supporting the application of EPS in heavy commercial vehicles, thereby realizing the high-efficiency application of the output power of the generator and the super capacitor.
Description
Technical Field
The invention belongs to the technical field of energy management of vehicle-mounted composite power supplies, and particularly relates to a multi-mode energy management method of an EPS composite power supply of a heavy-duty commercial vehicle.
Background
Electric Power Steering (EPS) is a currently accepted high-efficiency energy-saving steering system, but because the front axle load of a heavy commercial vehicle is large, the steering resistance torque required to be overcome at low speed is huge, and a power supply system of the whole vehicle cannot provide the required power of an EPS power-assisted motor, the EPS power-assisted steering system cannot be applied to the heavy commercial vehicle at present. The highway is developed rapidly nowadays, heavy commercial car is in the state of going at medium and high speed most of the time, and corresponding steering resistance moment is less, and whole car power can satisfy EPS helping hand motor's user demand completely. The super capacitor has the characteristics of instantaneous high-power charging and discharging, and the super capacitor and a finished automobile power supply form a composite power supply, so that the super capacitor has high power density and energy density, and the steering power requirement of the EPS power-assisted motor can be met.
After the composite power supply system is constructed, how to distribute the power of the double power supplies directly influences the working state of the EPS (electric power steering) power-assisted motor and the efficiency of the composite power supply system. The composite power supply is composed of a finished automobile power supply and a super capacitor, so that the inherent working characteristics of a generator and the super capacitor are considered in the aspect of energy management, the control logic of the energy management is formulated, and the power distribution of the composite power supply is optimized on the premise of meeting the use requirement of an EPS (electric power steering) motor.
Patent (JP2003-320942) discloses an EPS system based on a hybrid power supply, which provides a power supply mode of the hybrid power supply, and controls a change-over switch according to a detected steering wheel torque to enable a storage battery and a super capacitor to be in a parallel or series state. A patent (JP2007-223510) discloses an EPS system using a super capacitor as an auxiliary power supply, and gives a condition that the auxiliary power supply intervenes in the work. The patent (CN201180034669.7) discloses a fault detection circuit of an EPS system based on a hybrid power supply, and provides a fault detection and processing method. The patent (CN201410080799.X) provides an automobile electronic power-assisted steering system based on a super capacitor, and the super capacitor is matched with a main power supply to provide driving current and improve power-assisted power when steering under the bad road conditions. The hybrid power supply related to the above patent is composed of a storage battery and a super capacitor set, does not mention the energy management of a hybrid power supply system, and actually supplies power to an EPS system of a heavy commercial vehicle by a generator.
Disclosure of Invention
Aiming at the existing problems, the invention provides a multi-mode energy management method of a heavy commercial vehicle EPS composite power supply, which aims to solve the problem of power distribution of a finished vehicle power supply and a super capacitor of the heavy commercial vehicle EPS composite power supply.
In order to achieve the purpose, the specific technical scheme of the invention is as follows: a multi-mode energy management method for an EPS composite power supply of a heavy commercial vehicle comprises the following steps:
1) determining upper threshold operating mode switching parameters including critical steering vehicle speed v0And critical directionAngle of rotation of the disc thetah0；
2) Determining the optimal power interval of the generator according to the specification of the generator, and marking as [ P ]g-low,Pg-high]；
3) Calculating the critical voltage U of the super capacitorsc0；
4) Judging whether v is less than v0∩θh＞θh0(ii) a If yes, turning to the step 5); otherwise, turning to the step 8);
5) judging whether P is more than Pg-high(ii) a If yes, turning to step 6); if not, turning to the step 7);
6) switching the generator into a constant power output mode, and turning to the step 4);
7) switching the generator to an optimization mode 1, and turning to the step 4);
8) judging whether U is presentsc＜Usc0(ii) a If yes, turning to step 9); otherwise, turning to the step 10);
9) switching the generator into a super capacitor forced charging mode, and turning to the step 4);
10) judging whether P is more than Pg-low(ii) a If yes, turning to step 11); otherwise go to step 12);
11) switching the generator into a super capacitor to-be-charged mode, and turning to the step 4);
12) the generator is switched to an optimizing mode 2; go to step 4).
Where v is the vehicle speed, θhIs the steering wheel angle, P is the real-time power of the vehicle-mounted electrical appliance including EPS, UscIs the voltage of the super capacitor.
Further, in the above step 1), a critical steering vehicle speed v is determined0And critical steering wheel angle thetah0Comprises the following steps;
1.1) carrying out real vehicle test through a speedometer, a force measuring steering wheel and a steering resistance torque sensor, and collecting the vehicle speed v and the steering wheel rotation angle theta at different vehicle speedshSteering resistance torque T corresponding to timerObtaining sample data N:
N＝{(v1,θh1,Tr1),(v2,θh2,Tr2),...,(vi,θhi,Tri)}
wherein v is1,v2,...,viFor the collected vehicle speed, thetah1,θh2,...,θhiFor collected steering wheel angle, Tr1,Tr2,...,TriThe steering resistance torque is collected;
1.2) fitting sample data N by using a least square method to obtain the relation T between the steering resisting moment and the vehicle speed and the steering wheel rotating angler＝f(v,θh)；
1.3) calculating Tr＝f(v,θh) The gradient of (a) is taken as the critical steering vehicle speed v which is the vehicle speed and the steering wheel angle corresponding to the maximum modulus of the gradient0And critical steering wheel angle thetah0(ii) a The modulus of the gradient is calculated as follows:
in the formula (I), the compound is shown in the specification,
a mode that is a gradient;
further, in the step 3), the critical voltage U of the super capacitor is obtainedsc0The calculation comprises the following steps:
3.1) collecting the real-time steering wheel angle theta of the operation period T of the test vehiclehSpeed v and real-time steering moment Tr；
3.2) calculating the electric power P required by the EPS power-assisted motoreps-reqThe calculation formula is as follows:
in the formula, TrFor steering moment of resistance, TdTo expect steering hand force, ωmIs the rated speed, eta, of the booster motorrFor the transmission efficiency of the steering gear, GrTo the steering gear ratio, GmIs the transmission ratio of the speed reducing mechanism and the EPS power-assisted motor etamTo reduceEfficiency of the speed mechanism and the EPS-motor, etaepsEfficiency of the EPS booster motor;
3.3) calculating the average power P required by the EPS power-assisted motor in the operation period Teps-avgThe calculation formula is as follows:
3.4) counting the speed v lower than the vehicle speed0Highest-frequency power demand P of booster motorepsxAnd the corresponding steering vehicle speed vxAnd vehicle speed vxThe average time duration Δ t of time steering;
3.5) calculating the critical voltage U of the super capacitorsc0(ii) a Critical voltage U of super capacitorsc0Represents the required power P of the EPS power-assisted motorepsxThe voltage of the super capacitor is required; the following relationship is satisfied:
in the formula of UminRepresents the lowest voltage of the super capacitor; u shapemaxRepresents the highest voltage of the super capacitor; c represents the capacitance value of the supercapacitor.
Further, in the step 6), in the constant power output mode, the output power of the generator is Pg-highThe discharge of the super capacitor supplements the rest power, and the power distribution is as follows:
in the formula, PgRepresenting the output power of the generator, PgloadIndicating the power demand, P, of other electrical appliances on boardsc-DRepresenting the discharge power of the super capacitor.
Further, in the step 7), the power allocation method in the optimization mode 1 is as follows:
7.1) setting optimization target, optimizingThe aim is to minimize the system loss of the hybrid power supply, wherein the system power loss comprises the power loss L of the discharge of the super capacitorsc-DDischarge power loss L of super capacitor end DC/DC converterDC1And power loss L of generator-side DC/DC converterDC-gThe calculation formula is as follows:
in the formula Isc-DRepresents the discharge current of the super capacitor; rscRepresenting the internal resistance of the super capacitor; psc-DRepresenting the output power, P, of the supercapacitor-side DC/DC convertergepsRepresents the output power of the generator-side DC/DC converter; etaDC1The conversion efficiency of the DC/DC converter when the super capacitor is discharged is shown; etaDC-gThe conversion efficiency of the generator-side DC/DC converter is shown;
7.2) establishing a constraint condition, wherein the constraint condition is as follows:
in the formula, Psc-D-min,Psc-D-maxRespectively representing the minimum and maximum discharge power of the super capacitor, and determining according to the discharge power interval of the super capacitor.
7.3) deriving the difference [ P ] according to the constraint conditionsg,Psc-D]Feasible solution combination is respectively substituted into the optimization target to obtain the optimal solution [ Pg-best,Psc-D-best]Namely, the power distribution of the current vehicle power supply and the super capacitor is obtained.
Further, in step 9), in the forced charging mode of the super capacitor, the power distribution method includes:
in the formula, PgmaxIs the rated output power, P, of the generatorsc-CAnd (3) the input power of the DC/DC converter when the super capacitor is charged.
Further, in step 11), the power distribution method in the mode of waiting for charging the super capacitor is as follows:
further, in the step 12), the power allocation method in the optimization mode 2 includes the following steps:
12.1) establishing an optimization target, wherein the optimization target is that the loss of the composite power supply system is minimum; on the premise that the generator works in the high-efficiency interval, the system power loss comprises the charging power loss L of the super capacitorsc-CCharging power loss L of super capacitor end DC/DC converterDC2And power loss L of generator-side DC/DC converterDC-gThe calculation method is as follows:
wherein, Isc-CRepresenting the charging current, η, of the supercapacitorDC2The conversion efficiency of the DC/DC converter when the super capacitor is charged is shown.
12.2) establishing constraint conditions; the constraints are as follows:
wherein, Psc-C-min,Psc-C-maxRespectively representing the minimum charging power and the maximum charging power of the super capacitor, and determining according to the charging power interval of the super capacitor.
12.3) deriving the difference [ P ] according to the constraint conditionsg,Psc-C]Feasible solution combination is respectively substituted into the optimization target to obtain the optimal solution [ Pg-best,Psc-C-best]Namely, the power distribution of the current vehicle power supply and the super capacitor is obtained.
Further, in the above step 3.4), P is countedepsx、vxAnd Δ t, comprising the steps of:
3.4.1) screening out the speed v lower than the vehicle speed in the operation period T0At different speeds v and corresponding Peps-req；
3.4.2) statistics of v ∈ [0, v ∈ ]0]Time-assisted motor demand power Peps-reqFrequency of (f)1,f2,...,fnThe highest frequency f is obtained by comparisonmaxA 1 is to fmaxThe power demand and the steering speed of the corresponding power-assisted motor are respectively marked as PepsxAnd vx；
3.4.3) steering wheel angle theta obtained according to the collectionhTo obtain the vehicle speed vxTime duration t of steering1,t2,...,tnAnd averaging to obtain average steering time, and recording the average steering time as delta t:
further, the multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply is realized through a multi-mode device of the heavy-duty commercial vehicle EPS composite power supply, wherein the multi-mode device of the heavy-duty commercial vehicle EPS composite power supply comprises an EPS power-assisted motor, a controller, a generator, a super capacitor, a DC/DC converter, other vehicle-mounted electrical appliances, a corner sensor and a vehicle speed sensor; the generator and the super capacitor are respectively connected in series with a DC/DC converter, then the generator and the super capacitor are connected in parallel to form a composite power supply to supply power to the EPS (electric power storage) power-assisted motor, other vehicle-mounted electric appliances and the controller, and simultaneously the generator and the super capacitor respectively send power signals and terminal voltage signals of the generator and the super capacitor to the controller; the other vehicle-mounted electrical appliances are other electrical appliances except the above components; the corner sensor is used for acquiring a corner signal in real time, and the output end of the corner sensor is connected with the controller; the vehicle speed sensor is used for collecting vehicle speed signals in real time, and the output end of the vehicle speed sensor is connected with the controller; the EPS power-assisted motor sends a required power signal to the controller, and the input end of the EPS power-assisted motor is connected with the controller; the other vehicle-mounted electrical appliances send real-time power signals to the controller, the input end of the real-time power signals is connected with the generator, and the output end of the real-time power signals is connected with the controller; the controller judges the working mode of the hybrid power supply according to the collected corner signal, the vehicle speed signal, the required power sent by the EPS power-assisted motor and the real-time power sent by other vehicle-mounted electrical appliances, and the controller controls the DC/DC converter to distribute the output power of the whole vehicle power supply and the discharging/charging power of the super capacitor, so that efficient energy management of the hybrid power supply is realized.
Compared with the prior art, the energy management method provided by the invention can distribute the output power of the generator and the super capacitor in real time, and can enable the generator to work in the optimal working interval on the premise of meeting the requirement that the EPS is applied to a heavy commercial vehicle.
Drawings
Fig. 1 is a schematic structural diagram of an EPS hybrid power supply energy management device for a heavy-duty commercial vehicle.
Fig. 2 is a flow chart of a multi-mode energy management method of the heavy-duty commercial vehicle EPS hybrid power supply.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments, it should be noted that the technical solutions and design principles of the present invention are described in detail below only with one optimized technical solution, but the scope of the present invention is not limited thereto.
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.
FIG. 1 is a schematic structural diagram of an EPS composite power supply energy management device of a heavy-duty commercial vehicle, which comprises an EPS power-assisted motor, a controller, a generator, a super capacitor, a DC/DC converter, other vehicle-mounted electrical appliances, a corner sensor and a vehicle speed sensor; wherein:
the generator and the super capacitor are respectively connected in series with a DC/DC converter, then the generator and the super capacitor are connected in parallel to form a composite power supply which supplies power for the EPS (electric power storage) power-assisted motor, other vehicle-mounted electric appliances and the controller, and simultaneously the generator and the super capacitor respectively send power signals and terminal voltage signals to the controller;
the other vehicle-mounted electrical appliances are other electrical appliances except the components.
The corner sensor is used for collecting a corner signal in real time, and the output end of the corner sensor is connected with the controller;
the vehicle speed sensor is used for collecting vehicle speed signals in real time, and the output end of the vehicle speed sensor is connected with the controller;
the EPS power-assisted motor sends a required power signal to the controller, and the input end of the EPS power-assisted motor is connected with the controller;
the other vehicle-mounted electrical appliances send real-time power signals to the controller, the input end of the real-time power signals is connected with the generator, and the output end of the real-time power signals is connected with the controller;
the controller judges the working mode of the hybrid power supply according to the collected corner signal, the vehicle speed signal, the required power sent by the EPS power-assisted motor and the real-time power sent by other vehicle-mounted electrical appliances, and the controller controls the DC/DC converter to distribute the output power of the power supply of the whole vehicle and the discharging/charging power of the super capacitor, so that efficient energy management of the hybrid power supply is realized.
Fig. 2 is a flow chart of a multi-mode energy management method of the heavy-duty commercial vehicle EPS hybrid power supply. The method is realized on the energy management device of the hybrid power supply of the heavy-duty commercial vehicle EPS, and the working modes of the hybrid power supply of the heavy-duty commercial vehicle EPS comprise a generator constant power output mode, an optimization mode 1, a super capacitor forced charging mode, a super capacitor standby charging mode and an optimization mode 2.
The invention discloses a multi-mode energy management method of an EPS composite power supply of a heavy commercial vehicle, which specifically comprises the following steps as shown in figure 2:
1) determining upper threshold operating mode switching parameters including critical steering vehicle speed v0And critical steering wheel angle thetah0(ii) a The method specifically comprises the following steps;
1.1) taking a motor bus as a research object, carrying out real vehicle tests through a speedometer, a force measuring steering wheel and a steering resistance torque sensor, and collecting the results at different speeds v and steering wheel turning angles thetahSteering resistance torque T corresponding to timer(ii) a Obtaining sample data N:
N＝{(v1,θh1,Tr1),(v2,θh2,Tr2),...,(vi,θhi,Tri)}
wherein v is1,v2,...,viFor the collected vehicle speed, thetah1,θh2,...,θhiFor collected steering wheel angle, Tr1,Tr2,...,TriThe steering resistance torque is collected;
1.2) fitting sample data N by using a least square method to obtain the relation T between the steering resisting moment and the vehicle speed and the steering wheel rotating angler＝f(v,θh)；
1.3) calculating Tr＝f(v,θh) The gradient of (a) is taken as the critical steering vehicle speed v which is the vehicle speed and the steering wheel angle corresponding to the maximum modulus of the gradient0And critical steering wheel angle thetah0(ii) a The calculation method of the modulus of the gradient is as shown in formula (1):
in the formula (I), the compound is shown in the specification,
a mode that is a gradient;
2) determining the optimal power interval of the generator according to the specification of the generator, and marking as [ P ]g-low,Pg-high]；
3) Calculating the critical voltage U of the super capacitorsc0(ii) a The method specifically comprises the following steps:
3.1) collecting the real-time steering wheel angle theta of the operation period T of the test vehiclehSpeed v and real-time steering moment Tr(ii) a In a specific embodiment, the operation period T is taken to be 12 hours;
3.2) calculating the electric power P required by the EPS power-assisted motorepsThe calculation formula is shown as formula (2):
in the formula, TrFor steering moment of resistance, TdA desired steering hand force; omegamThe rated rotating speed of the power-assisted motor; etarThe transmission efficiency of the steering gear; grIs the steering gear ratio; gmThe transmission ratio of the speed reducing mechanism to the EPS power-assisted motor is shown; etamThe efficiency of the speed reducing mechanism and the EPS power-assisted motor; etaepsEfficiency of the EPS booster motor;
3.3) calculating the average power P required by the EPS power-assisted motor in the operation period Teps-avg(ii) a Wherein, the calculation method is as formula (3):
3.4) statistically obtaining the speed v lower than the vehicle speed0Highest-frequency power demand P of booster motorepsxAnd the corresponding steering vehicle speed vxAnd a vehicle speed vxThe average duration of the time steering Δ t. The specific statistical method is as follows:
3.4.1) screening out the speed v lower than the vehicle speed in the operation period T0At different speeds v and corresponding Peps-req；
3.4.2) statistics of v ∈ [0, v ∈ ]0]Time-assisted motor demand power Peps-reqFrequency of (f)1,f2,...,fnThe highest frequency f is obtained by comparisonmaxA 1 is to fmaxThe power demand and the steering speed of the corresponding power-assisted motor are respectively marked as PepsxAnd vx；
3.4.3) steering wheel angle theta obtained according to the collectionhTo obtain the vehicle speed vxTime duration t of steering1,t2,...,tnAnd averaging to obtain average steering time, and recording the average steering time as delta t:
3.5) calculating the critical voltage U of the super capacitorsc0(ii) a Critical voltage U of super capacitorsc0Represents the required power P of the EPS power-assisted motorepsxThe voltage of the super capacitor is required; the calculation method is obtained according to a charge state formula of the super capacitor, and the charge state formula is as follows (4):
identity transformation gives formula (5):
in the formula of UminRepresents the lowest voltage of the super capacitor; u shapemaxRepresenting the highest voltage of the supercapacitor.
4) Judging whether v is less than v0∩θh＞θh0(ii) a If yes, turning to the step 5); if not, turning to the step 8);
5) judging whether the real-time power P of the vehicle-mounted electrical appliance including the EPS is larger than Pg-high(ii) a If yes, turning to step 6); if not, turning to the step 7);
6) switching the generator into a constant power output mode, and turning to the step 4); wherein, in the constant power output mode, the output power of the generator is Pg-highDischarge of super capacitor to supplement othersPower; the power split is as in equation (6):
in the formula, PgRepresenting the output power of the generator, PgloadIndicating the power demand, P, of other electrical appliances on boardsc-DRepresenting the discharge power of the super capacitor.
7) Switching the generator to an optimization mode 1, and turning to the step 4); the power allocation method of the optimization mode 1 is as follows:
7.1) setting an optimization target, wherein the optimization target is that the loss of the composite power supply system is minimum, and the system power loss comprises the power loss L of discharge of the super capacitorsc-DDischarge power loss L of super capacitor end DC/DC converterDC1And power loss L of generator-side DC/DC converterDC-gThe calculation formula is shown in formula (7):
in the formula Isc-DRepresents the discharge current of the super capacitor; rscRepresenting the internal resistance of the super capacitor; psc-DRepresenting the output power, P, of the supercapacitor-side DC/DC convertergepsRepresents the output power of the generator-side DC/DC converter; etaDC1The conversion efficiency of the DC/DC converter when the super capacitor is discharged is shown; etaDC-gThe conversion efficiency of the generator-side DC/DC converter is shown;
7.2) establishing constraint conditions; the constraint is as in formula (8):
in the formula, Psc-D-min,Psc-D-maxRespectively representing the minimum and maximum discharge power of the super capacitor, and determining according to the discharge power interval of the super capacitor;
7.3) deriving the difference [ P ] according to the constraint conditionsg,Psc-D]Feasible solution combination is respectively substituted into the optimization target to obtain the optimal solution [ Pg-best,Psc-D-best]Namely, the power distribution of the current finished automobile power supply and the super capacitor is obtained;
8) judging whether the voltage U of the super capacitor is presentsc＜Usc0(ii) a If yes, turning to step 9); otherwise, turning to the step 10);
9) switching the generator into a super capacitor forced charging mode, and turning to the step 4); wherein, in the forced charging mode of the super capacitor, the power distribution method is as the following formula (9):
in the formula, PgmaxIs the rated output power, P, of the generatorsc-CAnd (3) the input power of the DC/DC converter when the super capacitor is charged.
10) Judging whether P is more than Pg-low(ii) a If yes, turning to step 11); otherwise go to step 12);
11) switching the generator into a super capacitor to-be-charged mode, and turning to the step 4); the power distribution method of the super capacitor to-be-charged mode is as follows (10):
12) the generator is switched to an optimizing mode 2; turning to step 4); the power allocation method of the optimization mode 2 is as follows:
12.1) establishing an optimization target, wherein the optimization target is that the loss of the composite power supply system is minimum; on the premise that the generator works in the high-efficiency region,the system power loss comprises super capacitor charging power loss Lsc-CCharging power loss L of super capacitor end DC/DC converterDC2And power loss L of generator-side DC/DC converterDC-gThe calculation method is as follows (11):
wherein, Isc-CRepresenting the charging current, η, of the supercapacitorDC2The conversion efficiency of the DC/DC converter when the super capacitor is charged is shown.
12.2) establishing constraint conditions; the constraint is as in formula (12):
wherein, Psc-C-min,Psc-C-maxRespectively representing the minimum charging power and the maximum charging power of the super capacitor, and determining according to the charging power interval of the super capacitor.
12.3) deriving the difference [ P ] according to the constraint conditionsg,Psc-C]Feasible solution combination is respectively substituted into the optimization target to obtain the optimal solution [ Pg-best,Psc-C-best]Namely, the power distribution of the current vehicle power supply and the super capacitor is obtained.
Claims (10)
1. A multi-mode energy management method for an EPS composite power supply of a heavy commercial vehicle is characterized by comprising the following steps:
1) determining upper threshold operating mode switching parameters including critical steering vehicle speed v0Steering wheel with critical angleAngle thetah0；
2) Determining the optimal power interval of the generator according to the specification of the generator, and marking as [ P ]g-low,Pg-high]；
3) Calculating the critical voltage U of the super capacitorsc0；
4) Judging whether v is less than v0∩θh＞θh0(ii) a If yes, turning to the step 5), otherwise, turning to the step 8);
5) judging whether P is more than Pg-high(ii) a If yes, turning to the step 6), otherwise, turning to the step 7);
6) switching the generator into a constant power output mode, and turning to the step 4);
7) switching the generator to an optimization mode 1, and turning to the step 4);
8) judging whether U is presentsc＜Usc0(ii) a If yes, turning to the step 9), otherwise, turning to the step 10);
9) switching the generator into a super capacitor forced charging mode, and turning to the step 4);
10) judging whether P is more than Pg-low(ii) a If yes, turning to step 11); otherwise go to step 12);
11) switching the generator into a super capacitor to-be-charged mode, and turning to the step 4);
12) the generator is switched to an optimizing mode 2; turning to step 4);
where v is the vehicle speed, θhIs the steering wheel angle, P is the real-time power of the vehicle-mounted electrical appliance including EPS, UscIs the voltage of the super capacitor.
2. The multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, characterized in that in the step 1), the critical steering vehicle speed v is determined0And critical steering wheel angle thetah0Comprises the following steps;
1.1) carrying out real vehicle test through a speedometer, a force measuring steering wheel and a steering resistance torque sensor, and collecting the vehicle speed v and the steering wheel rotation angle theta at different vehicle speedshSteering resistance torque T corresponding to timerObtaining sample data N:
N＝{(v1,θh1,Tr1),(v2,θh2,Tr2),...,(vi,θhi,Tri)}
wherein v is1,v2,...,viFor the collected vehicle speed, thetah1,θh2,...,θhiFor collected steering wheel angle, Tr1,Tr2,...,TriThe steering resistance torque is collected;
1.2) fitting sample data N by using a least square method to obtain the relation T between the steering resisting moment and the vehicle speed and the steering wheel rotating angler＝f(v,θh)；
1.3) calculating Tr＝f(v,θh) The gradient of (a) is taken as the critical steering vehicle speed v which is the vehicle speed and the steering wheel angle corresponding to the maximum modulus of the gradient0And critical steering wheel angle thetah0(ii) a The modulus of the gradient is calculated as follows:
in the formula (I), the compound is shown in the specification,
is the mode of the gradient.
3. The multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply as claimed in claim 1, wherein in the step 3), the super capacitor critical voltage U is setsc0The calculation comprises the following steps:
3.1) collecting the real-time steering wheel angle theta of the operation period T of the test vehiclehSpeed v and real-time steering moment Tr；
3.2) calculating the electric power P required by the EPS power-assisted motoreps-reqThe calculation formula is as follows:
in the formula, TrFor steering moment of resistance, TdTo expect steering hand force, ωmIs the rated speed, eta, of the booster motorrFor the transmission efficiency of the steering gear, GrTo the steering gear ratio, GmIs the transmission ratio of the speed reducing mechanism and the EPS power-assisted motor etamEfficiency of the reduction mechanism and the EPS-assist motor, etaepsEfficiency of the EPS booster motor;
3.3) calculating the average power P required by the EPS power-assisted motor in the operation period Teps-avgThe calculation formula is as follows:
3.4) counting the speed v lower than the vehicle speed0Highest-frequency power demand P of booster motorepsxAnd the corresponding steering vehicle speed vxAnd vehicle speed vxThe average time duration Δ t of time steering;
3.5) calculating the critical voltage U of the super capacitorsc0(ii) a Critical voltage U of super capacitorsc0Represents the required power P of the EPS power-assisted motorepsxThe voltage of the super capacitor is required; the following relationship is satisfied:
in the formula of UminRepresents the lowest voltage of the super capacitor; u shapemaxRepresents the highest voltage of the super capacitor; c represents the capacitance value of the supercapacitor.
4. The multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, wherein in the step 6), the output power of the generator is P in the constant power output modeg-highThe discharge of the super capacitor supplements the rest power, and the power distribution is as follows:
in the formula, PgRepresenting the output power of the generator, PgloadIndicating the power demand, P, of other electrical appliances on boardsc-DRepresenting the discharge power, P, of the supercapacitoreps-reqThe electric power needed by the EPS power-assisted motor.
5. The multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, wherein in the step 7), the power allocation method of the optimization mode 1 is as follows:
7.1) setting an optimization target, wherein the optimization target is that the loss of the composite power supply system is minimum, and the system power loss comprises the power loss L of discharge of the super capacitorsc-DDischarge power loss L of super capacitor end DC/DC converterDC1And power loss L of generator-side DC/DC converterDC-gThe calculation formula is as follows:
in the formula Isc-DRepresents the discharge current of the super capacitor; rscRepresenting the internal resistance of the super capacitor; psc-DRepresenting the output power, P, of the supercapacitor-side DC/DC convertergepsRepresents the output power of the generator-side DC/DC converter; etaDC1The conversion efficiency of the DC/DC converter when the super capacitor is discharged is shown; etaDC-gThe conversion efficiency of the generator-side DC/DC converter is shown;
7.2) establishing a constraint condition, wherein the constraint condition is as follows:
in the formula, Psc-D-min,Psc-D-maxRespectively representing the minimum and maximum discharge power of the super capacitor, and determining according to the discharge power interval of the super capacitor;
7.3) deriving the difference [ P ] according to the constraint conditionsg,Psc-D]Feasible solution combination is respectively substituted into the optimization target to obtain the optimal solution [ Pg-best,Psc-D-best]Namely, the power distribution of the current vehicle power supply and the super capacitor is obtained.
6. The multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, wherein in the step 9), in the super capacitor forced charging mode, the power distribution method is as follows:
in the formula, PgmaxIs the rated output power, P, of the generatorsc-CAnd (3) the input power of the DC/DC converter when the super capacitor is charged.
7. The multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, wherein in the step 11), the power distribution method of the super capacitor to-be-charged mode is as follows:
8. the multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, wherein in the step 12), the power allocation method of the optimization mode 2 comprises the steps of:
12.1) establishing an optimization target, wherein the optimization target is that the loss of the composite power supply system is minimum; on the premise that the generator works in the high-efficiency interval, the system power loss comprises the charging power loss L of the super capacitorsc-CCharging power loss L of super capacitor end DC/DC converterDC2And power loss L of generator-side DC/DC converterDC-gThe calculation method is as follows:
wherein, Isc-CRepresenting the charging current, η, of the supercapacitorDC2The conversion efficiency of the DC/DC converter when the super capacitor is charged is shown;
12.2) establishing constraint conditions; the constraints are as follows:
wherein, Psc-C-min,Psc-C-maxRespectively representing the minimum charging power and the maximum charging power of the super capacitor, and determining according to the charging power interval of the super capacitor;
12.3) deriving the difference [ P ] according to the constraint conditionsg,Psc-C]Feasible solution combination is respectively substituted into the optimization target to obtain the optimal solution [ Pg-best,Psc-C-best]Namely, the power distribution of the current vehicle power supply and the super capacitor is obtained.
9. The heavy-duty commercial vehicle EPS composite power supply of claim 3Method for multi-mode energy management of a source, characterized in that in said step 3.4), P is countedepsx、vxAnd Δ t, comprising the steps of:
3.4.1) screening out the speed v lower than the vehicle speed in the operation period T0At different speeds v and corresponding Peps-req；
3.4.2) statistics of v ∈ [0, v ∈ ]0]Time-assisted motor demand power Peps-reqFrequency of (f)1,f2,...,fnThe highest frequency f is obtained by comparisonmaxA 1 is to fmaxThe power demand and the steering speed of the corresponding power-assisted motor are respectively marked as PepsxAnd vx；
3.4.3) steering wheel angle theta obtained according to the collectionhTo obtain the vehicle speed vxTime duration t of steering1,t2,...,tnAnd averaging to obtain average steering time, and recording the average steering time as delta t:
10. the multi-mode energy management method of the heavy-duty commercial vehicle EPS composite power supply according to claim 1, characterized by being realized by a multi-mode device of the heavy-duty commercial vehicle EPS composite power supply, wherein the multi-mode device of the heavy-duty commercial vehicle EPS composite power supply comprises an EPS power-assisted motor, a controller, a generator, a super capacitor, a DC/DC converter, other vehicle-mounted electrical appliances, a rotation angle sensor and a vehicle speed sensor; the generator and the super capacitor are respectively connected in series with a DC/DC converter, then the generator and the super capacitor are connected in parallel to form a composite power supply which supplies power for the EPS (electric power storage) power-assisted motor, other vehicle-mounted electric appliances and the controller, and simultaneously the generator and the super capacitor respectively send power signals and terminal voltage signals to the controller; the other vehicle-mounted electrical appliances are other electrical appliances except the above components; the corner sensor is used for acquiring a corner signal in real time, and the output end of the corner sensor is connected with the controller; the vehicle speed sensor is used for collecting vehicle speed signals in real time, and the output end of the vehicle speed sensor is connected with the controller; the EPS power-assisted motor sends a required power signal to the controller, and the input end of the EPS power-assisted motor is connected with the controller; the other vehicle-mounted electrical appliances send real-time power signals to the controller, the input end of the real-time power signals is connected with the generator, and the output end of the real-time power signals is connected with the controller; the controller judges the working mode of the hybrid power supply according to the collected corner signal, the vehicle speed signal, the required power sent by the EPS power-assisted motor and the real-time power sent by other vehicle-mounted electrical appliances, and the controller controls the DC/DC converter to distribute the output power of the whole vehicle power supply and the discharging/charging power of the super capacitor, so that efficient energy management of the hybrid power supply is realized.
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| US4653601A (en) * | 1984-12-27 | 1987-03-31 | Toyoda Koki Kabushiki Kaisha | Electric power steering system for a motor vehicle |
| CN108177615A (en) * | 2017-12-06 | 2018-06-19 | 中国第汽车股份有限公司 | A kind of Energy Management System based on super capacitor |
| CN108622187A (en) * | 2018-05-09 | 2018-10-09 | 江苏大学 | The energy dynamics control system and method for composite power source EPS |
| CN108945089A (en) * | 2018-07-09 | 2018-12-07 | 江苏大学 | A kind of matching process of the heavy-duty commercial vehicle EPS composite power source based on power demand |
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| US4653601A (en) * | 1984-12-27 | 1987-03-31 | Toyoda Koki Kabushiki Kaisha | Electric power steering system for a motor vehicle |
| CN108177615A (en) * | 2017-12-06 | 2018-06-19 | 中国第汽车股份有限公司 | A kind of Energy Management System based on super capacitor |
| CN108622187A (en) * | 2018-05-09 | 2018-10-09 | 江苏大学 | The energy dynamics control system and method for composite power source EPS |
| CN108945089A (en) * | 2018-07-09 | 2018-12-07 | 江苏大学 | A kind of matching process of the heavy-duty commercial vehicle EPS composite power source based on power demand |
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