WO2009144112A1

WO2009144112A1 - Device and method for controlling a generator and generator comprising such a device

Info

Publication number: WO2009144112A1
Application number: PCT/EP2009/055344
Authority: WO
Inventors: Markus Beck; Ralf Piscol; Helmut Suelzle
Original assignee: Robert Bosch Gmbh
Priority date: 2008-05-30
Filing date: 2009-05-04
Publication date: 2009-12-03
Also published as: DE102008002118A1

Abstract

The invention relates to a device for controlling a generator, in particular a starter generator of a motor vehicle, in which the respective operating phase of the generator can be controlled by way of a controller. It is provided that the output of the generator, which experiences excitation phases and de-excitation phases due to an external input, is limited during the excitation phase of the generator. The invention further relates to a generator with such a device and a corresponding method.

Description

description

Title Device and method for generator control and generator with appropriate device

The invention relates on the one hand to a device for controlling a generator, in particular starter-generator, of a motor vehicle with the features mentioned in the preamble of claim 1 and a generator with a corresponding device with the features mentioned in the preamble of claim 8. On the other hand, the invention relates to a corresponding method for controlling a generator, in particular starter-generator, of a motor vehicle with the features mentioned in the preamble of claim 9.

State of the art

An apparatus and a method for controlling a generator of the type mentioned are known for example from US 6,166,523 A. In this case, depending on the state of charge of the vehicle battery and the operating state of the vehicle, the generator is turned on or off. By charging and discharging the battery of the vehicle based on its state of charge, a load caused by the generator can be reduced, thereby saving energy and optimizing the fuel efficiency of the vehicle. Based on set limit values of the state of charge of the vehicle battery, the generator can be switched on or off depending on whether the state of charge of the vehicle battery is within the limits. Consequently, the generator is turned on only when needed, which avoids unnecessary charging and the battery of the vehicle can be operated as efficiently as possible.

However, the efficiency of the generator is not constant over all operating conditions. He is rather dependent on his constructive interpretation and changes, for example, with speed and load as well as with the temperature. The optimum efficiency of the generator is at a capacity utilization of about 70%. When operating near full load or at low load, the efficiency is lower. A used in this context control unit is used to tune the respective operating condition of the generator with the entire vehicle. In this case, an application case, which is referred to as recuperation mode, can typically be taken into account. In Rekuperationsmodus an occurring braking energy is converted by an increase in the generator voltage into electrical energy in overrun operation of the vehicle, that is in a condition caused by the downgrade force and / or by the inertia force operation, and cached for example in the vehicle battery. When accelerating the vehicle, the generator output power of the generator is then reduced to its de-energizing to reduce the generator drag torque on a drivetrain of the vehicle and thus provide more torque for acceleration. During this time, the electrical system of the vehicle from the energy storage, for example, a battery supplied. Following this, for example, after completion of the acceleration process, the generator takes over again the supply of the electrical system and the recharging of the battery. In a typical vehicle cycle, after its de-energized state, the generator first transitions to its full load condition for a finite time, thereby less frequently operating the generator in the region of optimum efficiency. In extreme cases, the generator even switches between the conditions de-energizing and full load, so that operation of the generator is less or never in the range of optimum efficiency.

Disclosure of the invention

The device according to the invention for controlling a generator with the features mentioned in claim 1 offers the advantage that the time duration, while the generator is operated in the region of highest efficiency, increases, thereby ultimately both the fuel consumption of the internal combustion engine of the vehicle and its emission levels improved can be. In this case, there is a scheduled limitation of the power of the generator, which experiences excitation phases and de-excitation phases during an external excitation phase during the excitation phase. As long as the charge balance of the battery and other boundary conditions allow it, the power of the generator is limited to the operating state de-energizing. The limitation is such that a higher efficiency of the generator is achieved. The same applies analogously to the generator with a corresponding device having the features of claim 8 and to the method for controlling the generator with the features of claim 9.

Advantageous developments emerge from the features of the dependent claims.

Advantageously, the power of the generator is limited immediately after the de-excitation phase. The limitation is in this case, for example, to a value that has the highest efficiency.

Advantageously, the limitation of the power of the generator as a function of boundary conditions, in particular charge balance of a vehicle battery, so that the power limitation of the generator takes place only when certain conditions are met. Here, in particular, the vehicle battery is in the field of vision in the case of an electric or hybrid vehicle.

A further advantageous embodiment of the invention provides that the

Limiting the power of the generator is provided to a value for which a generator voltage is in a suitable area for a vehicle electrical system of the motor vehicle. The power of the generator can not be chosen arbitrarily. Rather, care must be taken when choosing the power that the generator voltage may be changed only in a limited range in order to ensure proper operation of the electrical system. The size of the area and a nominal voltage are specified by properties of the electrical system. A change in the power is thus such that, on the one hand, the generator voltage in the predetermined range is on the other hand, the efficiency of the generator is maximized.

In an advantageous embodiment of the invention, it is provided that the limitation of the power of the generator takes place on a value corresponding to the highest efficiency of the generator, whereby the generator is used significantly more frequently in the region of its optimum operating phase. As a result, although the recharging of the battery is delayed, but this does not affect the charge balance, if the frequency of these Bethebszustände is controlled accordingly.

According to a preferred embodiment of the invention, it is provided that the controlled limitation of the output power of the generator based on a specification of a maximum permissible excitation current, so that the generator can be brought into different states each with a relatively higher efficiency.

According to a further preferred embodiment of the invention, it is provided that the controlled limitation of the power of the generator based on a maximum allowable Einschaltverhältnisses a

Exciter circuit final stage takes place. In this case, for example, by means of a digital controller interface of a separate control device, the generator can be supplied with a corresponding signal.

The advantages of the dependent device claims 2 to 7 apply analogously to the features of the dependent method claims 9 to 14.

Brief description of the drawings

The invention and advantageous embodiments according to the features of the further claims are explained in more detail below with reference to the embodiments illustrated in the drawings, without limiting the invention so far occurs; rather, it encompasses all modifications, changes and equivalents that are possible within the scope of the claims. Show it: Figure 1 is an efficiency map of a generator with exemplified operating states thereof;

Figure 2 shows another efficiency map of the generator below

Consideration of a load point shift; and

3 shows a characteristic diagram of an internal combustion engine, in particular

Internal combustion engine, for the representation of the specific fuel consumption including the specific work and the engine or engine speed.

Embodiment (s) of the invention

1 shows a diagram 10 with an efficiency map 11 of a generator, not shown, in which the generator current I _G is plotted against the generator speed n _G. Here, for a given first speed, characterized by the line 12, depending on the output power of the generator, for example, three different operating conditions 13, 14 and 15 are set, but the efficiency of the generator is not constant over all operating conditions. The efficiency is rather dependent on the structural design of the generator and changes, for example, with the generator speed, the generator utilization and the generator temperature. The optimum efficiency of the generator is at a capacity utilization of about 70%. A used in this context control unit is used to tune the respective operating condition of the generator with the entire vehicle.

In this case, an application case, which is referred to as recuperation mode, can typically be taken into account. In Rekuperationsmodus an occurring braking energy is converted by the increase in the generator voltage into electrical energy and, for example, in an energy storage, such as the vehicle battery, cached in overrun mode of the vehicle. When accelerating the vehicle then the generator output power of the generator is up to its de-energizing reduced to reduce a generator drag torque on the drive train of the vehicle. During this time, an electrical system of the vehicle from the energy storage, for example, the vehicle battery supplied. In the wake of it, so usually with completed acceleration process, the generator takes over again the supply of the electrical system and the recharging of the battery.

In the recuperation mode, that is to say when electrical energy is recovered, for example during a braking operation of the vehicle, the operating state of the generator when charging the battery will assume the operating state 13 according to FIG. By a controlled limitation of the output power, the generator can be brought into the further operating states 14 and 15 according to FIG. 1 with higher efficiencies. In this case, a subarea 15.1 of the operating state 15 corresponds to a maximum of the efficiency of the generator. By means of an arrow 16, a tendency of the efficiency of the generator within the efficiency map 11 of Figure 1 is shown, which is decreasing with increasing generator current I _G and increasing generator speed n _G. The controlled limitation can, for example, by the specification of a maximum permissible excitation current or a maximum allowable Einschaltverhältnisses a

Exciter circuit final stage, wherein the generator can be supplied with a corresponding signal by means of a digital controller interface of a separate control unit.

According to Figure 2, a further efficiency map 17 of a generator is shown, in which the generator current I _G is plotted against the generator speed n _G. The further efficiency map 17 is hereby representative of a principle in which a load point shift is mapped. The efficiency map 17 is provided with a series of field segments 18 to 22, wherein the zero point of the illustrated

Coordinate system most obvious field segment 18 corresponds to an efficiency of> 70%. The other field segments 19, 20, 21 and 22 correspond in the order given an efficiency of>65%,>60%,> 55% or> 50%. A first field region 23, which is marked with a left-facing surface hatching forms in this Related a relevant first range for the load point shift. A second field region 24 adjacent below the first field region 23 thus forms the region in which the load point is to be displaced in order to improve the efficiency of the generator. Corresponding to the first field region 23, below the second field region 24 there is a third field region 25, which is identified by a surface hatching oriented to the right. The third field region 25 in this context forms a relevant further area for the load point shift. By way of example, a load point 26 is entered within the third field region 25, which is shifted in the direction of arrow 34 into the second field region 24 to the new load point 26 'to increase the efficiency of the generator, for example, the difference of the generator current + 20A and the difference of the generator speed +10 %. In the example shown, the generator current is increased by 2OA, which increases the efficiency by 10%.

3 shows a map 27 of an internal combustion engine, in particular internal combustion engine, for representing the specific fuel consumption (g / kWh) including the specific work and the engine or engine speed shown. The specific work w _e is shown here above the engine speed n _M. The specific work is the work done by an engine in terms of displacement, for example, in the dimension kJ / dnrA. It represents a comparison of different engines regardless of the engine's displacement. There is a distinction between indicated and effective specific work. While the indicated specific work results from the pressure history in the combustion chamber, the effective specific work according to Figure 3 refers to the work delivered to the shaft.

According to FIG. 2, three field regions are also defined in FIG. A first field region 28, which is marked with a left-facing surface hatching, forms in this context a relevant first region for the load point shift. A second field region 29 adjacent below the first field region 28 thus forms the region in which the load point is to be displaced in order to improve the efficiency of the generator. Corresponding to the first field region 28 is located Below the second field region 29, a third field region 30, which is marked with a right-facing surface hatching. Within the third field region 30, a load point 31 is shown by way of example which corresponds to a low specific work and is to be displaced according to the arrow direction 35 into the second field region 29 in order to achieve an increase in efficiency, thus resulting in an (exemplary) load point 31 '. Furthermore, a load point 32 is shown within the second field region 29, which can be reached at high specific work. In this respect, the map 27 illustrates the tendency direction 33 for the load point shift in a generator from the point of view of the internal combustion engine, in particular internal combustion engine.

A possible functional implementation of the load point shift essentially comprises, on the one hand, a basic function which has validity for the operating states acceleration, constant travel or idling of the internal combustion engine. On the other hand, by said functional implementation, a special case, in particular a push operation, are taken into account. In the basic function, the generator or the internal combustion engine is located in a functional area according to FIG. 2 or in a functional area according to FIG. 3. For this purpose, the following cases can be mapped according to a state machine, in particular according to the following assignment table:

Operating status Operating status Control

Generator combustion engine generator voltage U _{G SOII}

Field area 23 Field area 28 U _G soii = U _G normal - delta U _h

Field area 23 Field area 28 UG soii = UG normal - delta Uk

Field area 23 Field area 28 UG soii = UG normal

Field area 24 Field area 29 U _S oiι = U _G normal - delta U _k

Field area 24 Field area 29 U _G soii = U _G normal

Field area 24 Field area 29 U _G oi = U _G normal + delta U _k

Field area 25 Field area 30 UG soii = UG normal

Field area 25 Field area 30 UG soii = UG normal + delta Uk

Field region 25 Field region 30 U _S oi = U _G normal + delta U _n For the special case of overrun operation, a general increase in the generator voltage U _G to be achieved is to be applied, according to which UG SOII = U _G normal + delta U _h applies.

In the above cases, the following assignments are used: U _G soii = default value / setpoint of the operating voltage, U _G normal = normal operating voltage (temperature compensated), delta U _h = high voltage change (within the permissible range) and delta Uk = smaller voltage change than delta Uh

A load point shift may only take place in such a way that the output voltage of the generator is within the voltage ranges specified in the assignment table. In this case, U _G normally indicates the voltage which is usually used for the electrical system of the motor vehicle, while delta Uh specifies a maximum permissible voltage deviation and delta Uk specifies a smaller deviation. During normal operation of the vehicle (in the field _regions 24 and 29), the actual generator voltage U _{G SOII should be} in the range of U _G normal-delta U _k to U _G normal + delta U _k . In the case of unfavorable driving conditions (for example in one of the field regions 23, 25, 28 or 30), the deviation may be greater so that the generator voltage U _G soii can lie in the range from UG normal -delta Uh to UG normal + delta Uh. This limitation of the permissible generator voltage range thus limits the possible extent of a load point shift. The variables U _G normal, delta Uh, and delta Uk are determined by the requirements of the electrical system. The voltage U _{G SOII} can be _adjusted in the course of the load point shift such that an ideal possible efficiency of the generator is present.

A regulation of the generator voltage U _{G s} oiι can be done for example via an adjustment of the external excitation.

In summary, the present technical solution relates to a device and a method for controlling a generator, in particular a starter generator, of a motor vehicle, in which the respective operating phase of the generator is controlled by means of a control device. Here, the power of the generator, by an external specification excitation phases and De-energizing experiences during the excitation phase of the generator targeted and scheduled limits. Furthermore, the present invention relates to a generator with a corresponding device. The power limitation of the generator is to increase its efficiency, especially in the course of a load point shift.

Claims

claims

1. A device for controlling a generator, in particular starter-generator, of a motor vehicle, in which by means of a control device, the respective operating phase of the generator is controllable, characterized in that a limitation of the power of the generator, which experiences excitation phases and de-excitation phases by an external specification, during the arousal phase.

2. Apparatus according to claim 1, characterized in that the

Limiting the power of the generator is provided immediately after the de-energizing phase.

3. Device according to one of the preceding claims, characterized in that the limitation of the power of the generator in

Depending on boundary conditions, in particular a charge balance of a vehicle battery, is provided.

4. Device according to one of the preceding claims, characterized in that the limitation of the power of the generator is provided to a value for which a generator voltage is in a suitable area for a vehicle electrical system of the motor vehicle.

5. Device according to one of the preceding claims, characterized in that the limitation of the power of the generator is provided to a value corresponding to the highest efficiency of the generator.

6. Device according to one of the preceding claims, characterized in that the controlled limitation of the power of the generator is provided on the basis of a specification of a maximum permissible excitation current.

7. Device according to one of the preceding claims, characterized in that the controlled limitation of the power of the generator is provided on the basis of a maximum allowable Einschaltverhältnisses an exciter circuit output stage.

8. Generator, in particular starter-generator, of a motor vehicle, characterized by a device according to one of the preceding claims.

9. A method for controlling a generator, in particular starter-generator, a motor vehicle, in which by means of a control device, the respective operating phase of the generator is controlled, characterized in that the power of the generator, which experiences excitation phases and de-excitation phases by an external specification during the Excitation phase is limited.

10. The method according to claim 9, characterized in that the power of the generator is limited immediately after the de-energizing phase.

11. The method according to any one of the preceding claims, characterized in that the power of the generator as a function of boundary conditions, in particular a charge balance of a vehicle battery is limited.

12. The method according to any one of the preceding claims, characterized in that the power of the generator is limited to a value for which a generator voltage is in a suitable area for a vehicle electrical system of the motor vehicle.

13. The method according to any one of the preceding claims, characterized in that the power of the generator is limited to a value corresponding to the highest efficiency of the generator.

14. The method according to any one of the preceding claims, characterized in that the power of the generator is limited based on a specification of a maximum permissible excitation current controlled.

15. The method according to any one of the preceding claims, characterized in that the power of the generator is controlled based on a maximum allowable Einschaltverhältnisses an exciter circuit output stage.