CN104029671B - Automobile engine stop position control method - Google Patents

Abstract

The invention discloses a kind of automobile engine stop position control method, comprise the following steps: judge that present engine rotational speed omega is whether lower than the minimum ignition rotational speed omega of electromotor_Max；If present engine rotating speed is lower than minimum ignition rotating speed, i.e. ω < ω_Max, then continue to judge whether engine speed is 0；If engine speed is 0, then enter engine stop position control flow；Compared with prior art; it is an advantage of the current invention that: owing to ISG motor is coaxial with electromotor, and ISG motor has higher positional precision, when electromotor is shut down; stopped to the minimum position of the moment of resistance by ISG drive and control of electric machine electromotor, and can ensure that higher ISG system starts electromotor success rate.

Description

Automobile engine stop position control method

Technical field

The present invention relates to hybrid electric vehicle engine stop position control field, in particular to a kind of automobile engine stop position control method.

Background technology

Global energy and the severe situation of environment, the particularly international financial crisis enormous impact to automobile industry; promote countries in the world to accelerate transportation and energy's strategic transformation, become, with the new-energy automobile that hybrid vehicle, pure electric automobile and fuel cell car are representative, the important directions that future automobile develops.

Owing to electric automobile is currently but being faced with the difficulties such as continual mileage is short, battery price is expensive, infrastructure imperfection, it is necessary to the effort of quite a while is only possible to and progressively solves；And hybrid vehicle possesses better Industrialized conditions in present stage, China's development of automobile industry is of great significance by hybrid vehicle.This means that new-energy automobile power assembly is made up of electromotor and the motor driver of lower-wattage within one considerably long period.

Due to cost and weight, size, working condition restriction so that ISG system electrokinetic cell holds quantitative limitation, causes that its output characteristics is softer, and the low speed torque causing ISG system is limited so that the success rate that ISG system starts electromotor is limited；Plus electrokinetic cell when low temperature and high temperature, output when its output is than room temperature is low, causes that ISG system starts the success rate of electromotor when low temperature relatively low.

In one cycle of operation of electromotor, the moment of resistance of electromotor is different along with engine crankshaft position difference, a certain four cylinders in a cycle of operation, the engine drag curve (on 0 ° of corresponding cylinder fulcrum) as shown in Figure 1 that electromotor changes with crank position.Electromotor would generally be parked near the position that the moment of resistance is maximum; namely on cylinder near fulcrum; these point; power drive system needs to export bigger moment of torsion just can overcome engine resistance torque; drag engine start, owing to the driving force of power drive system is certain so that on cylinder, near fulcrum, start success rate limited; during low temperature, the success rate starting electromotor is lower.

It has been experienced that: at engine crankshaft diverse location, owing to the moment of resistance of electromotor is different, make under identical power drive system, start success rate different, be in the position that engine resistance torque is more little, engine start success rate is also more high, namely, when bent axle is near cylinder lower fulcrum (in Fig. 1 near 90 ° of multiple positions, less than 5 degree), success rate is started the highest, during room temperature, close to 100%.

Retrieve existing patent; hybrid electric vehicle controls the method (CN101180897A) of engine stop position; the method includes a) when described electromotor will be shut down; when the fuel cut-off provided to described electromotor, described motor is used to reduce engine speed according to the first engine speed reduction rate；B) after engine speed is decreased to the first engine speed; use described motor according to the second engine speed reduction rate; and monitor current crank position by processing the signal of crankshaft sensor and cam sensor, to calculate the number of times that described current crank position is consistent with given target engine stop position；And if c) described number of times more than predetermined number, and if practical engine speeds is equal to or less than the second reference rotation velocity, then when described current crank position is consistent with described target engine stop position, use the described motor described electromotor of stopping.

This invention, calculated the braking torque of ISG power drive system by CAN collection engine speed and crank position by entire car controller (HCU), by CAN, braking torque is issued electric machine controller, electric machine controller by given braking torque, electromotor is stopped to specifying position.Due to the restriction of CAN communication speed, therefore the method in document has bigger control time delay, and engine stop position belongs to Angle-domain imaging, it is desirable to higher realtime control, the method in document is poor effect in actual control.

Summary of the invention

Present invention aim to provide a kind of automobile engine stop position control method.

For achieving the above object, automobile engine stop position control method provided by the present invention, comprise the following steps:

Step 1) judged that present engine rotational speed omega is whether lower than the minimum ignition rotational speed omega of electromotor by electric machine controller_Max；

Step 2) if present engine rotating speed is lower than minimum ignition rotating speed, i.e. ω < ω_Max, then continue to judge whether engine speed is 0；

Step 3) if engine speed is 0, then enter engine stop position control flow；

Compared with prior art; it is an advantage of the current invention that: owing to ISG motor is coaxial with electromotor; and ISG motor has higher positional precision; when electromotor is shut down; stopped to the minimum position (in Fig. 1 90 ° of odd-multiple positions) of the moment of resistance by ISG drive and control of electric machine electromotor, and can ensure that higher ISG system starts electromotor success rate.

Have following different from patent of invention " method controlling engine stop position in hybrid electric vehicle " (claiming afterwards: retrieval invention):

1, for purpose different:

(1) retrieval invention: control stop position, is to when engine start, reduce the torque ripple and vibration that produce in air inlet, compression and expansion stroke process.

(2) present invention: be, by ISG power drive system, electromotor is parked in the position that engine resistance torque is minimum, when starting electromotor next time, with minimum electric flux, the shortest starting time, quickly drags to fire speed by electromotor；Thus (the including low temperature) of improving the various operating modes of electromotor starts success rate, shorten the starting time.

2, the target controlled is different:

(1) retrieval invention: shut down every time and control all to stop electromotor to identical point.

(2) present invention: for multicylinder engine, in electromotor one circle, engine resistance torque minimum bit is equipped with multiple spot, and each shutdown is parked in the point that engine resistance torque is minimum nearby；

3, thinking is controlled different:

(1) retrieval invention: < during the first rotating speed, engine speed reduces with fixed slope, and downtime is longer when engine speed；Being consistent number of times and engine speed with target stop position as stopping the Rule of judgment to target location by crank position, due to engine inertia, there is deviation in stop position and target location.

(2) present invention: when engine speed is < during the first rotating speed; poor with target stop position and electromotor current location in real time; input quantity is controlled as ISG electricity Braking system moment of torsion; closed loop control engine speed reduction rate; with the shortest time, electromotor can be stopped to target location; actual stop position and target stop position can be completely superposed in theory, accomplish floating.

4, control mode is different

(1) retrieval invention: calculated the braking torque of ISG power drive system by entire car controller (HCU) by CAN collection engine speed and crank position, by CAN, braking torque is issued electric machine controller, electric machine controller by given braking torque, electromotor is stopped to specifying position.Due to the restriction of CAN communication speed, therefore the method in document has bigger control time delay, and engine stop position belongs to Angle-domain imaging, it is desirable to higher realtime control, the method in document is poor effect in actual control.

(2) present invention: and ISG motor driven systems coaxial according to ISG motor and electromotor has the feature of higher position precision and torque precision, by electric machine controller directly according to current motor rotating speed, angle and the engine indicated torque that prestores, angularly position-force control algorithm, stops electromotor to target location.There is higher real-time and control accuracy.Control algolithm is clear, has higher feasibility.

Accompanying drawing explanation

Fig. 1 is engine drag curve.

Fig. 2 is the engine stop position Angle ambiguity theory diagram based on ISG system.

Fig. 3 is the engine stop position angle control system block diagram based on ISG system

Fig. 4 is that the engine stop position based on ISG system controls decision flowchart.

Fig. 5 is the engine stop position control flow chart based on ISG system.

Fig. 6 is engine stop position Angle ambiguity flow chart.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

The present invention is in electric machine controller master cpu, and the electromotor that prestores is with the angle point (corresponding angle) minimum with the mapping table of the moment of resistance and a Machine cycle intrinsic motivation moment of resistance.

After electromotor shuts down (namely rotating speed is zero) naturally, by the inquiry of electromotor rotation direction from the nearest control point of engine resistance torque minimum position, it is determined as target stop position, subsequently by controlling ISG motor, electromotor is stopped to specifying position.Hybrid electric vehicle engine stop position based on ISG system controls the control principle block diagram of device and controls system block diagram respectively as shown in Figures 2 and 3.

The method control method is simple, it is easy to realize in ISG control system；Can being stopped by electromotor in a cycle of engine to target stop position, angle control precision is high.

Below in conjunction with control flow chart, the present invention is described in further detail.

Realizing engine stop position control, first have to judge whether electromotor shuts down, only after electromotor is shut down, the engine stop position based on ISG system controls could start to perform, and concrete engine stop position controls determination flow as shown in Figure 4.

Step 1) judged that present engine rotational speed omega is whether lower than the minimum ignition rotational speed omega of electromotor by electric machine controller_Max；

Step 2) if present engine rotating speed is lower than minimum ignition rotating speed, i.e. ω < ω_Max, then continue to judge whether engine speed is 0；

Step 3) if engine speed is 0, then enter engine stop position control flow；

Engine stop position control flow is as it is shown in figure 5, it comprises the following steps:

Step 1) the target stop position θ * of electromotor is determined according to the rotation direction of present engine；

Step 2) calculate the maximum speed ω in stop position control process according to determined target stop position_max, shown in concrete calculating process such as formula (7)；

Step 3) electromotor is accelerated flag set, i.e. F=1；

Step 4) the ISG system maximum power torque Te of output_Max；

Step 5) judge whether engine speed reaches the maximum speed that stop position controls, i.e. ω >=ω_max；If not up to the maximum speed that stop position controls, i.e. ω < ω_max, then continue step 4, export maximum power torque Te_Max；If ω >=ω_max, then step 6 is entered；

Step 6) electromotor acceleration flag clear, i.e. F=0；

Step 7) enter engine stop position Angle ambiguity；

As shown in Figure 6, it comprises the following steps engine stop position Angle ambiguity flow process:

Step 1) judge whether engine speed is not 0；If engine speed is 0, then control flow terminates, and returns；If engine speed is not 0, enter step 2；

Step 2) according to current motor location θ and target stop position θ^*, calculate differential seat angle Δ θ；

Step 3) judge whether electromotor is parked in target stop position, namely whether Δ θ is 0；If Δ θ=0, then control flow terminates, and returns；If Δ θ ≠ 0, then enter step 4；

Step 4) according to the current rotational speed omega of electromotor and differential seat angle Δ θ, calculate braking torque Te, and export braking torque.

Maximum speed ω in the stop position control process being previously mentioned in the step 2 of above-mentioned engine stop position control flow_maxComputational methods be:

In electric machine controller master cpu, the electromotor that prestores is with the angle point (corresponding angle) minimum with the mapping table of the moment of resistance and a Machine cycle intrinsic motivation moment of resistance.

During ISG system output torque capacity, shown in the minimum angular acceleration such as formula (5) of dynamical system.

${\mathrm{\&beta;}}_1=\frac{{\mathrm{Te}}_{\max }-M_{\max }}{J}---\left(5\right)$

Wherein: β₁Minimum angular acceleration (the rad/s of dynamical system²)

Te_maxISG system output torque capacity (Nm)

M_maxElectromotor maximum resistance square (Nm)

J electromotor and ISG motor synthesis rotary inertia (kg m²)

Under minimum acceleration, being stopped by electromotor to the time specified needed for position as shown in formula (6), in position adjustments control process, corresponding engine peak speed is ω_max。

$t=\sqrt{\frac{J\&CenterDot;\mathrm{\&Delta;\&theta;}}{{\mathrm{Te}}_{\max }-M_{\max }}}---\left(6\right)$

Wherein: electromotor was stopped to the time (s) specified needed for position by t

The differential seat angle (rad) of the current stop position of Δ θ and target stop position

J electromotor and ISG motor synthesis rotary inertia (kg m²)

Te_maxISG system output torque capacity (Nm)

M_maxElectromotor maximum resistance square (Nm)

${\mathrm{\&omega;}}_{\max }=\sqrt{\frac{({\mathrm{Te}}_{\max }-M_{\max })\&CenterDot;\mathrm{\&Delta;\&theta;}}{J}}---\left(7\right)$

Wherein: ω_maxShut down the maximum motor speed (rad/s) in control process

The differential seat angle (rad) of the current stop position of Δ θ and target stop position

J electromotor and ISG motor synthesis rotary inertia (kg m²)

Te_maxISG system output torque capacity (Nm)

M_maxElectromotor maximum resistance square (Nm)

The computational methods of the braking torque Te needing output being previously mentioned in the step 4 of above-mentioned engine stop position Angle ambiguity flow process are:

Due to, upper limit rotating ratio when stop position controls is relatively low, ignores movement resistor moment.

According to kinesiology relative theory:

Te (t)-M (θ)=J β (1)

Wherein: Te (t) ISG motor current electromagnetic torque (Nm)

M (θ) the engine system moment of resistance (Nm)

θ ISG position angle/crank position angle (rad)

J electromotor and ISG motor synthesis rotary inertia (kg m²)

β angular acceleration (rad/s²)

ω (t)=ω₀+β·t(2)

Wherein: ω (t) current time dynamical system angular velocity (rad/s)

ω₀Stop position controls dynamical system initial angular velocity (rad/s)

β angular acceleration (rad/s²)

T shuts down and controls elapsed-time standards (s)

D θ=ω (t) dt (3)

Wherein: d θ angle variable quantity (rad)

ω (t) current time dynamical system angular velocity (rad/s)

Dt time variation amount

Stop position controls to terminate angular velocity omega=0 of rear dynamical system, if the angle variable quantity from current location to stop position is Δ θ (t), combines (1), (2), (3) formula, solves:

$\mathrm{Te}\left(t\right)=M\left(\mathrm{\&theta;}\right)-\frac{J\&CenterDot;{{\mathrm{\&omega;}}_0}^2}{2\mathrm{\&Delta;\&theta;}\left(t\right)}---\left(4\right)$

Wherein: Te (t) ISG motor current electromagnetic torque (Nm)

M (θ) the engine system moment of resistance (Nm)

θ ISG position angle/crank position angle (rad)

J electromotor and ISG motor synthesis rotary inertia (kg m²)

ω₀Stop position controls dynamical system initial angular velocity (rad/s)

Δ θ (t) angle variable quantity (rad) from current location to stop position

What above-mentioned side adopted is that angle Closed loop track controls, and angle control precision is high, after adopting engine stop position to control, can improve ISG system and start the success rate of electromotor, shorten the time starting electromotor.

Above-described embodiment is the present invention preferably embodiment; but embodiments of the present invention are also not restricted to the described embodiments; the change made under other any spirit without departing from the present invention and principle, modification, replacement, combination, simplification; all should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (1)

1. an automobile engine stop position control method, it is characterised in that comprise the following steps:

Step 1) judged that present engine rotational speed omega is whether lower than the minimum ignition rotational speed omega of electromotor by electric machine controller_Max；

Step 2) if present engine rotating speed is lower than minimum ignition rotating speed, i.e. ω < ω_Max, then continue to judge whether engine speed is 0；

Step 3) if engine speed is 0, then enter engine stop position control flow；

Described step 3) in engine stop position control flow comprise the following steps:

Step 31) the target stop position θ * of electromotor is determined according to the rotation direction of present engine；

Step 32) the maximum motor speed ω shut down in control process is calculated according to determined target stop position_max, concrete calculating process is such as shown in following formula:

${\mathrm{\&omega;}}_{max}=\sqrt{\frac{({\mathrm{Te}}_{max}-M_{max})\&CenterDot;\mathrm{\&Delta;}\mathrm{\&theta;}}{J}},$

Wherein: ω_maxShut down the maximum motor speed (rad/s) in control process；

The differential seat angle (rad) of the current stop position of Δ θ and target stop position；

J electromotor and ISG motor synthesis rotary inertia (kg m²)；

Te_maxThe torque capacity (Nm) of ISG system output；

M_maxElectromotor maximum resistance square (Nm)；

Step 33) electromotor is accelerated flag set, i.e. F=1；

Step 34) ISG system output torque capacity Te_max；

Step 35) judge whether engine speed reaches to shut down the maximum motor speed in control process, i.e. ω >=ω_max；If not up to the maximum motor speed shut down in control process, i.e. ω < ω_max, then step 34 is continued), ISG system output torque capacity Te_max；If ω >=ω_max, then step 36 is entered)；

Step 36) electromotor acceleration flag clear, i.e. F=0；

Step 37) enter engine stop position Angle ambiguity；

Described step 37) in engine stop position Angle ambiguity flow process comprise the following steps:

Step 371) judge whether engine speed is not 0；If engine speed is 0, then control flow terminates；If engine speed is not 0, enter step 372)；

Step 372) according to current motor location θ and target stop position θ^*, calculate differential seat angle Δ θ；

Step 373) judge whether electromotor is parked in target stop position, namely whether Δ θ is 0；If Δ θ=0, then control flow terminates；If Δ θ ≠ 0, then enter step 374)；

Step 374) according to the current rotational speed omega of electromotor and differential seat angle Δ θ, calculate braking torque Te, and export braking torque.