DE102007026164A1 - Electrical supply system for motor vehicle, has battery charging ultra cap by direct current-direct current converter before start of vehicle on high stress than rated stress, where stress level of electrical system is determined - Google Patents

Abstract

The system has a battery (4) separated by a circuit unit during start process of an electrical system (B). The battery charges an ultra cap (2) by a direct current (DC)-DC converter (3) before start of a vehicle on a high stress than a rated stress. A stress level of the electrical system is determined during recuperation of stress produced from an electrical generator (G) and/or recuperation brakes. The electrical system stress is equal to an output stress of the generator after the recuperation process and in normal operation.

Description

The The present invention relates to a simple concept for a motor vehicle with UltraCap and battery, as well as with special Control for start and recuperation.

State of the art

The motor vehicle electrical system will become increasingly important in the future. Due to the increasing energy recovery z. B. at start-stop and recuperation, the electrical system must meet additional requirements. In addition, the battery failures, which according to ADAC statistics account for up to 30% of vehicle failures, should be significantly reduced. UltraCap solutions as described in the following patent applications EP 1410482 . DE 10250488.1 . DE 10305939.3 . DE 10313081.0 , provide a basis for this.

in the August issue of the automotive electronics of the publishing house "modern industry "are other reasons for battery failure described as well as the battery management and the use of UltraCap (UCAP). A good approach to reducing battery failures Use of a battery sensor and shutdown of consumers is realized in the Audi A6 (built in 2006). There is also a control unit for energy and quiescent current management (ER 4).

In The above-mentioned patent documents, the electrical system for either two voltages for high current consumers and over a DC / DC converter with 12-14 V output voltage for Normal consumers designed. This requires major changes on systems and components.

A major problem is the ability to start the vehicle, especially if the battery has a poor state of charge or has lost capacity due to acid stratification. In both cases, a large internal resistance prevents sufficient starting current, especially at low temperatures. In the DE 100 21 155 C1 a DC / DC converter is described which supplies a battery with a higher voltage. This battery supplies the starter and special high-current consumers, such. B. the electric steering. The rest of the electrical system is supplied by the generator and the first battery with the conventional voltage. A disadvantage is the high cost and unsuitability for recuperation, ie the recovery of electrical energy during braking.

One Another problem to be solved is the undervoltage of Electrical system up to 5 V at the start.

task The present invention is a simple wiring system concept to provide, which meets the new requirements.

These Task is solved with the features of claim 1. Further advantageous embodiments of the switching device according to claim 1 result from the features of the subclaims.

Advantageous can the vehicle electrical system according to the invention without major changes to systems and components integrate into existing vehicle systems. In addition, draws It has a good startability for start-stop function, Relief of the battery with less failures and recuperation out.

The Inventive electrical system concept with power and Energy management advantageously fulfills the following requirements:

Energy management:

• a. needs-based and
• b. Situational control of generator power

• to a. depending on load, battery charge, compensation the leakage currents at several stores, eg UCap from battery
• to b. Recuperation in appropriate memory, control of Generator power during acceleration or energy supply and Energy recovery during and after recuperation, if necessary increase the generator voltage.
• Goal: min. fuel consumption

Power Management:

• • Power distribution in individual Current paths and their protection against short circuits
• • Power distribution in the multi-voltage vehicle electrical system
• • Starting the vehicle
• • Circuit of the vehicle electrical system components in case of failure such as Generator or battery z. B. to ensure the function of Indicators or brake
• • Jumpstart
• • polarity reversal protection
• • Shutdown of the current paths in case of a crash
• • Protection of vehicle electrical system against impulse load and overvoltage
• • min. el. losses and min. Harness Weight

• Target: fail-safe circuit without risk of fire

Due to the advantageous separation of the battery from the vehicle electrical system and the power supply of the on-board network with UltraCap and generator, pulse loads no longer burden the battery and recuperation is possible via the generator with higher voltage up to 15-20 V. Regeneration is carried out by switching off the generator to or below the voltage level of the battery. The start In turn, the battery is discharged via the UltraCap. To improve the start after a long vehicle standstill, the UltraCap is powered by a DC / DC converter with an electric power from the battery of z. B. supplied less than 10 watts and balanced at the same time the leakage current of UCaps. This are the start z. B. 16-20 V available, which causes a higher starting speed with a shorter start time, especially when the engine is cold. The battery is only switched on for charging and for supplying the vehicle electrical system at start and for emergency driving in the event of generator failure. Even if the UltraCap is disconnected from the vehicle electrical system via switching means, the battery directly supplies the quiescent current consumers. The shutdown of the memory in the event of a crash is advantageous. The upper voltage limit for UltraCap and generator is limited by the dielectric strength of the controllers and components, which is in the range 15-20V. The higher the voltage, the better the generator efficiency and performance, which is critical for fuel economy.

The higher voltage can be used to advantage when the Engine in warm-up is higher and especially in winter Load is switched on. In this case, the recuperation waived. It is therefore useful the systems and components for a short time higher voltage up to 20 V. Since this is the case only at low temperatures, the realization is preparing because of the low temperature level, especially the semiconductor, no big problems.

Also can a higher voltage level of the UltraCaps only for Start to be used by using appropriate switching means Only the systems that are required for startup are switched on. These needed systems need in this case be designed for the higher voltage.

For the operation of higher voltage systems, e.g. B. electrical Power steering, can be another DC / DC converter, preferably with relatively small memory for the pulse load, are used.

One Another advantage for the electrical system is the use of Switching means against reverse polarity. It is also advantageous that the Battery can be dimensioned considerably smaller, z. B. on 50%, which means significant weight savings. Due to smaller cable cross sections due to the lower starting current, a weight reduction is also achieved.

By Separation of the electrical system when starting and disconnecting from UCap and supply battery voltage never falls below 10-12 V from the battery which gives considerable advantages in the dimensioning of the components result.

The inventive concept offers a simple and cost-effective solution for the start, start-stop and recuperation with significant discharge of the battery and Reduction of failures.

The Figure shows a circuit concept for a possible Design of the electrical system according to the invention. This is mainly for start-stop function and minimization the battery failures and recuperation trained.

To the load of the battery 4 To keep low, especially in strong load fluctuations even by strong current pulses, is the battery 4 normally disconnected via the switch S _B from the electrical system. A powerful generator G supplies circuit I over the line 26 , The UltraCap 2 serves to cover heavy loads. It starts with the UltraCap 2 , At longer standstill, a small DC / DC converter charges 3 the UltraCap 2 from the battery 4 on z. B. 20V. As a result, the starting process, especially at low temperatures by higher speed faster and safer. The DC / DC converter 3 also balances the leakage current of the UCap 2 10%, after which it is switched off to avoid a deeply discharged, ie no longer chargeable battery. The DC / DC converter 3 is powered by Power and Energy Management (PEM) 7 controlled. By starting the motor vehicle by means of the UCap 2 becomes the battery 4 no longer burdened by the high starting currents, which has the consequence that the life of the battery is considerably extended and even starting at low residual capacity is still possible because only a small amount of current to charge the UCap 2 via the DC / DC converter 3 necessary is. With conventional sizing, a battery with a capacity of less than 30% at low temperatures is no longer bootable. The battery is needed when the vehicle is at a standstill to supply the quiescent consumers at startup to supply the star-relevant systems or the entire consumer. It is also required for emergency driving in case of failure of the generator or short-term heavy load z. B. in extreme cases, when the generator power is insufficient. Accordingly, the capacity must be sized, which makes it possible to reduce the battery by more than 50%, which means a considerable space and weight reduction.

at low temperatures, the electrical system with max. Voltage (eg 16-20 V), what the generator efficiency and performance worth mentioning elevated. In this context is a sizing the systems to higher voltages at low temperatures meaningful.

To charge the battery switch S _{B is} closed and thus with the generator G and ucap 2 connected with appropriate voltage. The battery monitoring preferably SOC (state of change) and SOH (state of health) takes over a battery sensor 5 , which via a line in connection with the PEM 7 by recording the balance of the charging and discharging currents and correspondingly adding the missing charge to full capacity. A conventional temperature sensor can also be omitted, since charging and discharging currents are low and thus the self-heating. This has the battery 4 When installing in the tail section about outside temperature. As a result, the battery is always fully charged, which significantly affects the life. The PEM 7 controls via switching means 8th the quiescent current and 14 V normal consumers, as well as all star-relevant consumers of the electrical system, which via a bus with the PEM 7 communicate. The switch means 8th are shown here only in principle. This concept allows in addition to a reduction in battery size and a reduction in the weight of the lines, since z. B. the battery line only for the performance of Notfahrverbraucher less than 100 A and not 1000 A must be measured. In addition, the starter line can be made smaller, as a higher voltage and a lower internal resistance of the UCap 2 compared to the battery 4 can be used. In addition, the battery size can be significantly reduced because it is no longer used for starting and essentially only for rare emergency driving and to supply the quiescent consumers. It is thereby despite smaller battery 4 the startability of previously several weeks vehicle standstill improved by factors. The dashed lines are measuring and control lines 6 for the PEM 7 , Essentially for voltage and current and in the generator, the line is used to control the voltage regulator. In contrast to the conventional electrical system, in which the upper voltage limit is determined by the battery, with higher voltage z. B. 16 V are driven, which can be used in recuperation. Here then the generator G after charging the UCap 2 then switched off until the voltage on z. B. 12 V drops. Prerequisite for this is the voltage regulation of voltage-sensitive components such. B. light bulbs.

With this concept, it makes sense to use further switching means. The UCap 2 can be disconnected via the switch S _S from the electrical system, resulting in a higher starting voltage by charging the UCaps 2 can be used. Here, the electrical system is powered by the battery. Furthermore, the UCap 2 be separated in the event of a crash of the vehicle by means of the switch S _K from the electrical system. Furthermore, a switching means S _F for connection to the Fremdstartanschluss 9 be used. This closes when the correct polarity and voltage are detected at the measuring point behind the diode. As a result, overvoltage during startup can be eliminated.

The Switching means can be relays, semiconductors or over be a shift drum actuated mechanical contacts.

To the main power line 1 can be another DC / DC converter 11 for voltage boosting z. B. to 26 V for special consumers 13 , preferably with impulse loading, are used. It is advantageous to add another UCap 12 to complete.

The switching means S _S can also be used for a short time as a linear regulator or step-down converter to regulate the vehicle electrical system B to a lower voltage at a higher generator voltage. As a result, voltage-dependent short-term consumers, such as window or Sitzverstellmotoren can still operate safely. Optionally, with clocked switching means S _S a smoothing memory in the form of a capacitor smooth the voltage of the electrical system B, which is standard in many on-board networks.

To reduce the quiescent current consumption is another small DC / DC 15 with 50 mA, which is connected to the battery and supplies the quiescent current consumers with vehicle standstill with 6-8 V. This is a reduction of the quiescent current consumption and thus a battery relief possible. In this case, the battery must be disconnected from the electrical system.

1

Main supply line

2

ucap

3

DC / DC converter 12 / 16-20 V

4

battery

5

battery sensor

6

signal line

7

Power- and energy management

8th

switching means

9

Jump-starting connection

10

Verpoldiode

11

DC / DC 12V ... <20V

12

ucap 2

13

consumer with higher voltage

14

Switching means S _S to start

15

DC / DC 12-6 / 8V

16

Signal-BUS

17

starter

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1410482 [0002]
• - DE 10250488 [0002]
• - DE 10305939 [0002]
• - DE 10313081 [0002]
• - DE 10021155 C1 [0005]

Claims (22)

Electrical supply system for a motor vehicle with a voltage level, at least one battery ( 4 ), at least one UltraCap ( 2 ) and a generator (G), characterized in that the battery ( 4 ) is separated at a higher voltage in the electrical system (B) than the nominal voltage and at startup from the electrical system (B) by means of a switching means (S _B ), and that the battery ( 4 ) the UltraCap ( 2 ) by means of a DC / DC converter ( 3 ) is charged to a higher voltage than the nominal voltage before the start of the vehicle, wherein during recuperation the voltage generated by the electric generator (G) and / or Rekuperationsbremsen determines the voltage level of the electrical system (B), and that after the Rekuperationsprozess and in normal operation Vehicle electrical system voltage equal to the output voltage of the generator (G). Electric supply system for a motor vehicle, an electric generator (G), an electric battery ( 4 ), a starter ( 17 ) as well as an UltraCap ( 2 ), wherein the UltraCap ( 2 ) either by means of the generator (G) or by means of a DC / DC converter via the battery ( 4 ) is chargeable, wherein during the braking process, a partial conversion of the kinetic energy of the vehicle is in electrical energy (recuperation), and the outputs of the generator, the UltraCaps and the battery by means of switching means depending on the vehicle condition with a multi-consuming vehicle electrical system (B) a voltage level are connectable, characterized in that - the output of the generator (G) via an electrical connection line ( 26 ) is connected to a first switch (S _S ), with which the generator (G) to the electrical system (B) is connectable, and that - the positive terminal of the UltraCap ( 2 ) directly or via an optional second switch (S _K ) with the connecting line ( 26 ) is or is connectable, - and that via a third switch (S _St ) of the starter ( 17 ) with the connecting line ( 26 ) or the positive pole of the UltraCap ( 2 ) is connectable, - and that the positive pole of the battery via a fourth switch (S _B ) with the electrical system (B) can be brought into connection, - and that the first switch (S _S ) and the fourth switch (S _B ) between Generator (G) and battery ( 4 ) are connected in series, between the switches (S _S , S _B ), the tap for the electrical system, - and that between the positive pole of the battery and the positive terminal of the UltraCap a DC / DC converter ( 3 ) is switched. Electrical supply system according to claim 2, characterized in that - the output of the generator (G) via an electrical connecting line ( 26 ) is connected to a first terminal (S _S1 ) of a first switch (S _S ) and that - the positive terminal of the UltraCap ( 2 ) directly or via an optional second switch (S _K ) with the connecting line ( 26 ) is or is connectable, - and that via a third switch (S _St ) of the starter ( 17 ) with the connecting line ( 26 ) or the positive pole of the UltraCap ( 2 ) is connectable, - and that the positive pole of the battery is electrically connected to the first terminal (S _B1 ) of a fourth switch (S _B ), - and that the second terminal (S _S2 ) of the first switch (S _S ) and the second terminal (S _B2 ) of the fourth switch (S _B ) are connected to each other and to the electrical system (B), - and that between the positive pole of the battery and the positive terminal of the UltraCap a DC / DC converter is connected. Electrical supply system according to one of claims 1 to 3, characterized in that the supply system comprises a control device ( 7 ), which switches the switches (S _S , S _K , S _B , S _St ) depending on the vehicle condition. Electrical supply system according to one of claims 2 to 4, characterized in that the control device ( 7 ) by means of a battery sensor ( 5 ) the state of charge and the capacity of the battery ( 4 ). Electrical supply system according to one of the preceding claims, characterized in that the switch (S _K ) the UltraCap ( 2 ) in extreme cases, especially in an accident, separated. Electrical supply system according to one of the preceding claims, characterized in that before and / or during the start of the vehicle, the UltraCap ( 2 ) by means of a switching means (S _S ) from the electrical system (B) and the battery ( 4 ) and that the electrical system (B) by means of the closed switch (S _B ) with the positive pole of the battery ( 4 ). Electrical supply system according to one of the preceding claims, characterized in that in normal operation and during recuperation of the output of the generator via a closed switching means (S _K ) with the positive terminal of the UltraCaps ( 2 ) and via a closed switch (S _S ) with the electrical system in connection, the battery by means of the open switch (S _B ) from the electrical system (B) is disconnected. Electrical supply system according to one of the preceding claims, characterized in that in case of failure of the generator (G) in Driving the vehicle electrical system (B) by means of the switch (S _B ) with the positive pole of the battery ( 4 ) is connectable. Electrical supply system according to one of the preceding claims, characterized in that the consumers of the electrical system (B) by means of additional switching means ( 8th ) Are disconnected from the power supply or with this Connectable. Electrical supply system according to one of the preceding claims, characterized in that individual consumers by means of the additional switching means ( 8th ) are disconnectable from the power supply during the startup process. Electrical supply system according to one of the preceding claims, characterized in that during the starting process, the electrical system (B) via the switch (S _B ) with the battery ( 4 ) in electrical connection and by means of the switch (S _S ) of the starter ( 17 ) is disconnected. Electrical supply system according to one of the preceding Claims, characterized in that the consumers of the vehicle electrical system (B) are designed for a voltage level, which occurs during recuperation. Electrical supply system according to claim 13, characterized in that the consumers to a voltage of 16 to 30 volts, in particular designed for 20 volts, in such a way that by means of the Ge nerators, especially at low temperatures, a voltage of up to 30 volts, in particular up to 20 volts, to Power supply of the electrical system (B), z. B. for feeding the heater and / or high-performance consumers, can be generated. Electrical supply system according to one of the preceding claims, characterized in that an additional DC / DC converter ( 11 ) the voltage of the electrical system (B) to supply additional consumers ( 13 ), which require a higher voltage, high. Electrical supply system according to claim 15, characterized in that by means of the additional DC / DC converter ( 11 ) an additional memory, in particular an UltraCap ( 12 ) is rechargeable. Electrical supply system according to one of the preceding claims, characterized in that an additional DC / DC converter ( 15 ) reduces the voltage of the electrical system (B) for the supply of quiescent current consumers, which require a smaller voltage than the vehicle electrical system voltage. Electrical supply system according to one of the preceding claims, characterized in that the control device ( 7 ) operates the switch (S _S ) in the sense of a buck converter to reduce the voltage of the electrical system (B) relative to the generator voltage or the UltraCap voltage. Electrical supply system according to one of the preceding claims, characterized in that at least the switching means (S _S , S _B ) and their control are integrated together with the DC / DC converter in the so-called Vorsicherungsbox, which includes, inter alia, fuses, especially high current fuses. Electrical supply system according to one of the preceding claims, characterized in that the upper voltage level of the generator (G) according to the power consumption of the electrical system (B) and the lower voltage level of the generator according to the battery voltage ( 4 ) is designed. Electrical supply system according to one of the preceding claims, characterized in that the switches (S _S , S _K , S _B , S _St ) are formed as semiconductor switching elements and / or relays. Electrical supply system according to one of the preceding Claims, characterized in that an integrated Starter generator with appropriate control lines the starter and replaced the generator.