DE102012212498B4 - Electric torque control for a motor vehicle - Google Patents

Abstract

Method (200, 300, 400) for controlling a motor vehicle (105).
- An electrical machine (110) for influencing the speed of the motor vehicle (105);
- An electrical energy store (115) for exchanging energy with the machine (110), and
- An electrical consumer (120, 125, 135), comprising the following steps:
- Changing (215, 320, 410) of the consumer (120, 125, 135) consumed electrical energy;
- to this, changing (220, 315, 420) the energy converted by the electrical machine in the opposite direction,
- wherein the electrical energy converted by the machine (110) is changed successively over a predetermined period of time, characterized by
- an anticipatory determination (210, 310) of the change in the electrical energy consumed by the consumer (120, 125, 135),
- wherein the change in the energy converted by the machine (110) is initiated (220, 315) before the change in the energy converted by the consumer (120, 125, 135).

Description

The invention relates to a motor vehicle with an electrical machine, the speed of the motor vehicle being able to be influenced by means of the electrical machine. In particular, the invention relates to a controller for the electrical machine.

A motor vehicle can include an electric machine that is set up to accelerate the motor vehicle by converting electrical energy or to decelerate it by providing electrical energy. The electrical energy can come from an electrical energy store, in particular a high-voltage battery. In one embodiment, no further drive system is provided, so that the motor vehicle can be referred to as an electric vehicle. In another embodiment, an internal combustion engine is also provided as the drive, in which case the motor vehicle can be referred to as a hybrid vehicle.

The electrical energy exchange between the electrical machine and the electrical energy store is usually limited on the one hand by the performance of the electrical machine and on the other hand by the electrical load capacity of the energy store. In addition, part of the energy transmitted between the electrical machine and the electrical energy store can be diverted to operate an electrical consumer. For example, an electrical heating device can be operated from the electrical energy store.

If the power consumption of the consumer changes, it may be necessary to reduce the drive or deceleration power of the electric machine in order not to exceed the drawing or absorption capacity of the electric energy store. If the change in the power consumption of the consumer occurs suddenly, the associated change in torque of the electric machine can lead to a jolt in the motor vehicle, which can be noticeably uncomfortable for a driver or occupants of the motor vehicle. Furthermore, the sudden change in torque can promote wear and tear on the motor vehicle.

DE 10 2007 016 513 A1 relates to a method for gradually increasing a drive torque of an electric drive motor when an output torque capacity suddenly increases.

DE 10 2011 111 025 A1 proposes applying a torque to an internal combustion engine in overrun mode by means of an electric motor in order to prevent the internal combustion engine from stopping unintentionally.

DE 198 57 916 A1 relates to a technique for controlling electrical consumers in a motor vehicle.

DE10201754A1 deals with a method for regulating the electrical voltage supplied by a generator to an electrical vehicle electrical system. To reduce the electrical power loss when the battery is fully functional, the battery state of charge is monitored by means of a battery state detection and the generator voltage is regulated to the minimum maintenance voltage when the battery is fully charged and to a higher voltage when the battery is not fully charged.

It is the object of the invention to provide a method, a computer program product and a control device by means of which driving in the motor vehicle described is possible with little jolting. The invention solves this problem by means of a method, a computer program product and a control device with the features of the independent claims. Subclaims reflect preferred embodiments.

A method according to the invention for controlling a motor vehicle with an electrical machine for influencing the speed of the motor vehicle, an electrical energy store for exchanging energy with the machine and an electrical consumer comprises steps of changing the electrical energy consumed by the consumer and changing the energy converted by the electric machine in the opposite direction , wherein the electrical energy converted by the machine is changed successively over a predetermined period of time.

By successively instead of abruptly changing the electrical energy converted by the electrical machine, the motor vehicle can be operated with little or even no jerks. In this way, the required change in the torque acting on the motor vehicle by the electric machine can take place gently, so that it is not uncomfortable or not noticeable at all for an occupant of the motor vehicle. In this case, the period of the successive change can be firmly predetermined in order to ensure the smoothness. The period of time can also be determined dynamically, for example on the basis of the speed of the electric machine, in which case a high speed can be assigned a short time period and a low speed can be assigned a long time period.

In a first alternative, the electric machine works in motor mode to drive the motor vehicle and the energy consumed by the consumer is increased. In this case, the energy converted by the electrical machine is successively reduced. The entire energy drawn from the electrical energy store cannot exceed a predetermined amount.

In a second alternative, the electric machine works in generator mode to decelerate the motor vehicle (“recuperator”), with the energy consumed by the consumer being reduced. In this case, the energy converted by the electrical machine is successively increased. The energy consumption of the electrical energy store can thus remain below a predetermined threshold value.

The energy converted by the machine is preferably changed linearly, ie in the form of a ramp. As a result of the linear change, the energy converted by the electric machine can be adapted relatively quickly, while at the same time the change in the electric energy is carried out gently, so that the motor vehicle jerks less or not at all.

In one embodiment, the energy converted by the machine is changed in such a way that, together with the energy consumed by the consumer, it does not exceed a predetermined absorption or release capacity of the energy store. The ability of the energy store to absorb or release energy can be permanently predetermined or dependent on the operating parameters of the electrical energy store.

For example, the ability to absorb electrical energy can depend on a state of charge or a temperature of the energy store. The successive change in the energy converted by the electric machine can be carried out independently of this in such a way that the motor vehicle can be operated with little or no jolting, regardless of a required change in torque of the electric machine that corresponds to the change in the electric energy converted by it.

The change in the electrical energy consumed by the consumer is determined in advance and the change in the energy converted by the machine is initiated before the change in the energy converted by the consumer. In particular, loads that can be influenced in terms of their change in output or the time of their change in output can be controlled so that the change in torque of the electric machine initially reduces the total energy input into the electric energy store or taken from it. A risk of exceeding the electrical load capacity of the energy store can be reduced in this way. In addition, load peaks at the moment the load is switched on or off can be rendered harmless for the energy store.

In a preferred embodiment, the energy consumption of the electrical consumer is changed gradually or successively. The change in the energy consumption of the consumer can thus correspond approximately to the change in the energy consumption of the electrical machine. As a result, jerk-free operation can be provided in an improved, energy-efficient manner.

In a further embodiment, the electrical load comprises a switchable and a controllable component, with the energy consumption of the electrical load being changed gradually by controlling the controllable component. In particular, if the switchable component cannot be influenced in terms of its behavior over time and it is also not possible to determine the change in the power consumption of the switchable component in advance, the total energy consumed by the consumer can be changed more slowly by appropriate control of the controllable component. This measure can contribute to enabling the motor vehicle to be operated with less jerks or in an energetically more favorable manner.

In one embodiment, the controllable component is set up to exchange energy with a further electrical energy store on board the motor vehicle. The controllable component can in particular be a direct voltage converter (DC-DC converter), which converts a high voltage in the area of the electrical machine and the energy store into a lower voltage in the rest of the vehicle electrical system. Another battery can be provided in the rest of the vehicle electrical system, from which, in one embodiment, the DC-DC converter can draw energy and provide it to the high-voltage side. The capacity of the battery of the vehicle electrical system can thus be used to avoid or dampen changes in acceleration (jerking) of the motor vehicle when there is a change in the power consumption of the consumer.

A computer program product according to the invention comprises program code means for carrying out the method described when the computer program product runs on a processing device or is stored on a computer-readable data carrier.

A control device according to the invention for a motor vehicle with an electric machine for influencing the speed of the motor vehicle, an electric energy store for exchanging energy with the machine and an electric consumer is set up to successively increase an energy converted by the electric machine in the opposite direction to a change in the electric energy consumed by the consumer change. The control device is also set up to anticipate the change in the electrical energy consumed by the consumer and to initiate the change in the energy converted by the machine before the change in the energy converted by the consumer.

• 1 ein Antriebssystem an Bord eines Kraftfahrzeugs; und
• 2 bis 4 Ablaufdiagramme von Verfahren zur Steuerung des Antriebssystems des Kraftfahrzeugs von 1 und korrespondierende Leistungsaufnahmen von Elementen des Kraftfahrzeugs darstellt.

The invention will now be described in more detail with reference to the attached figures, in which:

• 1 a propulsion system on board a motor vehicle; and
• 2 until 4 Flowcharts of methods for controlling the drive system of the motor vehicle from 1 and corresponding power consumptions of elements of the motor vehicle.

1 shows a drive system 100 on board a motor vehicle 105. The drive system 100 includes an electric machine 110, which can be coupled to the wheels of the motor vehicle 105, and an electrical energy store 115 for exchanging energy with the electric machine 110. The electric machine 110 can be in motor mode be used to drive motor vehicle 105 on the basis of electrical energy that is drawn from electrical energy store 115 . Conversely, electric machine 110 can also be used to decelerate motor vehicle 105 , electrical energy being introduced into energy store 115 .

Part of the electrical energy provided by electrical machine 110 or electrical energy store 115 can be used to operate an electrical load. In 1 a first electrical consumer 120 and a second electrical consumer 125 are shown as examples. The first electrical load 120 can, for example, include an electrical heater or an air conditioner, while the second electrical load 125 is shown here as a direct current converter (DC-DC converter) which is set up to exchange electrical energy with an on-board network 130 of the motor vehicle 105 .

The vehicle electrical system 130 can include one or more third electrical loads 135 and optionally a further electrical energy store 140 . Accordingly, the DC-DC converter 125 can represent a consumer that combines all the elements 135 , 140 connected to the vehicle electrical system 130 . In practice, the DC-DC converter 125 separates the low-voltage vehicle electrical system 130 from a high-voltage part, which includes at least the electrical machine 110 and the energy store 115, in the present illustration also the first electrical consumer 120. In certain situations, a negative consumers 125 arise when energy is released from the additional energy store 140 via the DC-DC converter 125 to the high-voltage part.

Furthermore, a control device 145 is provided, which is set up to control one or more of the electrical consumers 120, 125 and 135 and the electrical machine 110 in each case with regard to their electrical power.

In particular, control device 145 is set up to successively change the drive or deceleration power provided by electric machine 110 if one of loads 120, 125 or 140 changes its energy consumption behavior and electrical energy store 115 is operating close to the limits of its positive or negative current carrying capacity.

2A shows a flowchart of a first method 200 for controlling the drive system 100 of the motor vehicle 105 from FIG 1 . The method 200 shown assumes that the relevant consumer 120, 125, 135 announces the change in its power consumption or that its power consumption can be controlled. In a first step 205, it is detected that the energy store 115 is being operated close to its input or output limit, ie that the current intensity taken from the energy store 115 or the current intensity input into it is close to a permissible limit.

In a subsequent step 210, a request from one of the loads 120, 125 or 135 is received to change its current or power consumption. Then, in a step 215, the power consumption of the consumer 120, 125, 135 in question is changed successively, preferably in a ramp shape, while at the same time or after previously in a step 220 the energy consumption of the electrical machine 110 is changed successively, preferably in a ramp shape. The method ends in a step 225.

2 B shows the process described for the case that the electric machine 110 is operated as a motor. In the horizontal direction is a time entered a power in the vertical direction. A first curve 230 represents the electrical power of the electrical machine 110 and a second curve 235 the electrical power of the relevant consumer 120, 125 or 135. A load capacity of the electrical energy store 115 is limited to a value indicated by a broken horizontal line is. The request from step 210 occurs at a point in time t1. The successive changes in steps 215 or 220 occur up to a point in time t2. A simultaneous change in the energy balances of the electrical machine 110 and the consumer 120, 125 or 135 is assumed here.

2C shows a corresponding relationship when operating the electric machine 110 as a generator.

If the consumer 120, 125, 135 cannot be controlled in terms of its performance, but can only be switched, but an impending change in the power consumption of the consumer 120, 125, 135 can be detected, a method can be 3 be performed. 3A shows the flowchart, 3B and 3C in each case energy balances analogous to that 2 B or. 2C . Steps 305 and 310 correspond to steps 205 and 210 of method 200, respectively 2A . However, step 315, which corresponds to step 215, is completed before step 320, which corresponds to step 220, is entered. The method 300 then ends in a step 325.

In the 3B and 3C it can be seen how step 310 is carried out at time t1 and step 315 is carried out between times t1 and t2, before step 320 is only subsequently started, namely at time t2.

If the change in the energy consumption of the consumer 120, 125, 135 is neither controllable nor known in advance, a method 400 can be used, which is 4 is shown. 4A shows a flowchart corresponding to the illustrations of 2A and 3A , while 4B temporal relationships according to the 2 B , 2C , 3B and 3C represents.

Step 405 of method 400 corresponds to steps 305 and 205. In a subsequent step 410, which is carried out at a point in time t1, a change in the energy consumption of a first consumer 120, 125, 135 is detected. The effect of this change in the energy consumption occurs immediately, so that another consumer 120, 125, 135 has to be reduced in its power or switched off in order to ensure that the energy storage device 115 is not subjected to a greater load than permissible. In 4B , which relates to motor operation of the electrical machine 110, a third profile 240 shows the energy consumption of this additional consumer 120, 125, 135. The reduction in the power consumption of the additional consumer 120, 125, 135 continues until step 420 is completed, in which the power consumption of the electrical machine 110 was reduced in a ramped manner between the times t1 and t2.

In an alternative embodiment, the power of the additional consumer 120, 125, 135 can also be reduced immediately and then gradually increased again in a ramp shape or in some other way while step 420 is being carried out. A fourth profile 245 shows such a variant. In total, the two consumers then correspond to a consumer 120, 125, 135 whose maximum power consumption is reduced compared to the sum of the individual powers and whose power consumption can be controlled at least in certain areas.

The method 400 then ends in a step 425.

Reference List

100

drive system

105

motor vehicle

110

electric machine

115

electrical energy storage

120

first electrical consumer

125

second electrical consumer

130

electrical system

135

third electrical consumer

140

further electrical energy storage

145

control device

200

first procedure

205

Detect energy storage near load limit

210

Receive request consumer

215

Change consumer energy consumption successively

220

Change the energy consumption of the electrical machine successively

225

End

230

first course (machine)

235

second course (consumer)

240

third course (additional consumer)

245

fourth course (additional consumer)

300

second procedure

305

Detect energy storage near load limit

310

Receive request consumer

315

Change the energy consumption of the machine in a ramp-like manner

320

Switch energy consumption consumers

325

End

400

third procedure

405

Detect energy storage near load limit

410

Receive change in energy consumption consumer 1

415

Change energy consumption of consumer 2 in a ramp shape

420

Change the energy consumption of the machine in a ramp-like manner

425

End

Claims (10)

Method (200, 300, 400) for controlling a motor vehicle (105) with - an electric machine (110) for influencing the speed of the motor vehicle (105); - an electrical energy store (115) for exchanging energy with the machine (110), and - an electrical consumer (120, 125, 135), comprising the following steps: - changing (215, 320, 410) the consumer (120, 125, 135) absorbed electrical energy; - Changing (220, 315, 420) the energy converted by the electrical machine in the opposite direction to this, - the electrical energy converted by the machine (110) being changed successively over a predetermined period of time, characterized by - a predictive determination (210, 310) the change in the electrical energy consumed by the consumer (120, 125, 135), - the change in the energy converted by the machine (110) being initiated (220, 315) before the change in the energy converted by the consumer (120, 125, 135) becomes. Method (200, 300, 400) after claim 1 , wherein the electric machine (110) works in motor mode to drive the motor vehicle (105) and the consumer (120, 125, 135) consumed energy is increased. Method (200, 300, 400) after claim 1 , wherein the electric machine (115) works in generator mode to decelerate the motor vehicle (105) and the consumer (120, 125, 135) consumed energy is reduced. A method (200, 300, 400) according to any one of the preceding claims, wherein the energy dissipated by the machine (110) is linearly varied (220, 315, 420). Method (200, 300, 400) according to any one of the preceding claims, wherein the energy converted by the machine (110) is changed (220, 315, 420) in such a way that it is consumed together with that consumed by the consumer (120, 125, 135). Energy does not exceed a predetermined absorption or release capacity of the energy store (115). Method (200, 300, 400) according to one of the preceding claims, wherein the energy consumption of the electrical consumer (120, 125, 135) is gradually changed (220, 315, 420). Method (200, 300, 400) according to one of the preceding claims, wherein the electrical consumer comprises a switchable (120, 125, 135) and a controllable component (120, 125, 135) and the energy consumption of the electrical consumer by controlling the controllable component (120, 125, 135) is gradually changed. Method (200, 300, 400) after claim 7 , The controllable component (120, 125, 135) being set up to exchange energy with a further electrical energy store (140) on board the motor vehicle. Computer program product with program code means for carrying out a method (200, 300, 400) according to one of the preceding claims, when the computer program product runs on a processing device or is stored on a computer-readable data carrier. Control device (145) for a motor vehicle with: - an electric machine (110) for influencing the speed of the motor vehicle (105); - An electrical energy store (115) for exchanging energy with the machine (110); - an electrical consumer (120, 125, 135), - the control device (145) being set up to determine in advance a change in the electrical energy consumed by the consumer (120, 125, 135) and to Converted energy in the opposite direction to a change in electrical energy consumed by the consumer (120, 125, 135). To change energy successively, the change in the energy converted by the machine (110) being initiated before the change in the energy converted by the consumer (120, 125, 135) (220, 315).

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