DE29919099U1 - Device for starting aid and a starting aid connection in motor vehicles with high electrical system voltage, e.g. 42/14 V vehicle electrical system, using a symmetrical clocked DC / DC converter - Google Patents

Description

Utility model application

Device for jump-starting and a jump-start connection for motor vehicles

with high vehicle electrical system voltage, e.g. 42 / 14V vehicle electrical system, by means of a

symmetrical switched DC/DC converter

Applicant:

MICRU Silicon Design House GbR mbH Klinger Weg 10a
D-64853 Otzberg

File number :

Registration date:
28.10.99

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Device for starting a vehicle with a starting aid connection

with high vehicle electrical system voltage, e.g. 42 / 14V vehicle electrical system, by means of a

symmetrical switched DC/DC converter

The invention relates to a device for starting motor vehicles with high on-board voltage, e.g. 42V, by combining a special battery arrangement and using special battery-symmetrical two/four-quadrant DC/DC converters
In the future 42V electrical system of motor vehicles, 36/42V batteries will be used. If these batteries are empty and the vehicle is to be started using a jumper cable from another vehicle, the old method of connecting the two vehicle batteries with a jumper cable no longer works, as it must generally be assumed that the vehicle providing assistance still has a 12/14V electrical system. In the worst case, connecting the batteries can lead to an explosion of the batteries.

The solution to the problem is that in the 36/42V vehicle the battery is made up of several individual batteries, such as 3 x 12V or 12V+24V or a 36V battery with a 12V tap. Covers, for example, must be used to ensure that only the mass of the battery and the 12V tap of the battery(s) are visible to an outsider. An outsider can use his jumper cable to connect his 12V battery from his vehicle to this connection/tap for jump starting without anything changing for him compared to previous systems. The battery-symmetrical DC/DC converter in the 42V vehicle as shown in Figures 1 to 3 ensures that the energy made available at the 12V tap is evenly distributed to the other battery cells and the 42V vehicle can then start.

Even during operation, 42V and 12V consumers can be connected directly to the battery, as the invention ensures that the charge level of the battery cells remains identical despite different loads due to the symmetrization.

The principle is easiest and most advantageous to use in systems with conventional standard lead batteries. However, symmetrization also has advantages in other battery technologies. The converter described can also be used as a bidirectional DC/DC converter for e.g. 12V/14V to convert energy fed into the output to the 42V voltage.

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The OG/Q^WanÜlec/Verstärkfii* shown in Figure 4 can be implemented particularly cost-effectively and with few components compared to conventional DC/DC converters which have been optimized for single-quadrant operation and which are discussed in forums and discussion events of the automotive industry as a power supply for 12/14V devices in the high-voltage vehicle network. Converters of this type have been publicly presented by component manufacturers such as Linear Technology Inc or automotive suppliers such as Delphi, for example at the vehicle network forum of the company SICAN F+E GmbH, Hanover.

The subcomponents of the invention have already been tested in practice. The two/four-quadrant DC/DC converters shown in Figure 4b and Figure 4c have already been extensively described and tested in audio applications. Their circuits are in principle comparable to the designs of servo amplifiers for motors and regenerative DC-DC converters.

The invention relates to the arrangement of the battery and the design of the special DC/DC converter with the characterizing features of the claims according to the system and enables a very reliable, EMC-optimized and cost-effective solution to the problem.

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Block diagrams and technical details BeacJfreiburggidfer solution

Figure 1 shows the arrangement of the symmetrical DC-DC converter for a system consisting of a conventional 12 V battery and a 24 V battery, which can be constructed, for example, from two 12 V batteries connected in series.

Figure 2 shows the arrangement of the symmetrical DC-DC converter for a system consisting of a 36 V battery with a 12 V tap.

Figure 3 shows the arrangement of the symmetrical DC-DC converter from Figures 1 and 2 as a bidirectional DC/DC converter whose output is used as a universal jump start connection and which, at the same time, with an additional support capacitor at the output, can take over the 12V/14V supply for the on-board network, provided this is not realized via decentralized DC/DC converters.

Figure 4 shows the equivalent circuit diagrams of the converter in Figures 1-3 (Figure 4a) and the cost-effective implementation option using a self-oscillating precision D amplifier (Figure 4b) or a particularly low-emission bidirectional Cuk converter.

The arrangements behave like a two/four quadrant amplifier whose duty cycle is set to approximately 1:2 via the 1:2 voltage divider with the three resistors R. This creates an average output voltage of 1/3 of the supply voltage at the output, i.e. 12V when the 36V battery is charged.

Using the example of the self-oscillating D amplifier, the behavior is explained as follows. If the 12V battery connected to the output falls below 12V, it receives energy via S1. The arrangement behaves like a buck converter. If the voltage at the 36V battery terminal is less than 3 x the voltage at the 12V battery, e.g. with an external jump starter, S2 draws energy from the 12V connection via L and pumps it to the 36V connection like a boost converter.

While the current through the inductance L is uniform, the currents at the supply voltage points of the converter are clocked. With an appropriate layout, the resulting EMC interference can be sufficiently dampened. The basic circuit must still be supplemented by a current limiter. The associated techniques are well known in electrical drive technology.

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The self-oscillating converter has the decisive advantage over the DC-DC converters that are also suitable for this application, such as those built with components from LTC, Unitrode, Maxim, etc., that it is very precise and corrects the error voltage stored in capacitor C1. This means that it is able to correct the terminal voltage and thus the charge level of batteries in the mV range precisely and with little effort.

Due to the tap for the negative feedback of the free-running converter in front of the output inductance, the converter behaves like a first-order controlled system and therefore has a very high stability compared to the converter concepts with multiple negative feedback and tapping of the actual variable at the output of the filter choke.

The integrator can be extended with an additional capacitor and resistor for noise shaping, which shifts the noise level of the converter to higher frequencies that are easier to filter out.

The circuit of the converter is described in detail in the literature and has also been tested in practice:

1. Heinrich Kümmeke; Controllable oscillator for numerous practical applications; ELEKTRONIK 1980, Issue 1

2. Klaus Gruppenbacher; Linear switching amplifier with high power, thesis St 1773 LIT, TH Darmstadt 1980

3. Herbert Sax; Switching instead of heating, HiFi audio power amplifier with pulse width modulation; ELEKTRONIK 1988, issue 23

4. Michael König; switching regulators for alternating voltages;

ELECTRONICS 1988, Issue 23
130

The DC/DC converter can also be constructed as a two/four-quadrant Cuk converter as shown in Figure 4c. The converter is described in detail in US Patent No. 4186437, US 4184197, 3716826 and 3923311.1 and is particularly suitable for the application under EMC aspects.

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Claims (11)

1. Jump start connection in a vehicle with a high-voltage on-board network for a conventional jump start cable as shown in Figure 1-2 for a jump start from a 12/14 V battery/on-board network consisting of three identical batteries connected in series, or a battery with 12 V and a battery with 24 V or a 36 V battery with 12 V tap and a symmetrical two/four-quadrant DC/DC converter, whereby the physical interface in the form of a battery connection for the jump start is the same as in the previous system. 2. Starting aid connection according to claim 1, characterized in that the symmetrical two/four-quadrant DC/DC converter is realized with the circuit concepts according to Figure 4b and Figure 4c, with which the battery arrangement at the 12/14 V and 36/42 V connection can be loaded differently by consumers. 3. Jump start connection according to claim 1, characterized in that to realize a universal jump start connection and simultaneous 12 V source for 12/14 V consumers according to Figure 3, the symmetrical two/four quadrant DC/DC converter according to the circuit concepts according to Figure 4b and Figure 4c is used. 4. Starting aid connection for the realization of the two/four-quadrant DC/DC converter in claim 1 as a self-oscillating class D amplifier according to Figures 4b and 4c, which exactly symmetrizes the batteries and keeps the batteries at the same charge level by charge exchange. 5. Correction of the output voltage of the DC/DC converter according to claim 1 for exact charge compensation with an integrating error amplifier, in the simplest case an integrator corresponding to the input stage in Figure 4b and Figure 4c. 6. Stabilization of the DC/DC converter according to claim 5 by tapping the internal negative feedback before the output filter 7. Reduction of the noise level of the DC/DC converter according to claim 5 by using noise shaping known from audio technology in sigma-delta A/D and D/A converters. 8. Realization of the two/four quadrant converter according to claim 1 as a two/four quadrant Cuk converter according to Figure 4c, according to US Patent 4186437, US Patent 4184197 Patent No. 3716826 and 3923311.1 9. Protection of the arrangements according to claim 1 against destruction by supplementing the basic circuits in Figure 4b and Figure 4c with a current limiter in order to comply with maximum charging currents of the battery and to protect the circuit itself. 10. Protection of the arrangement according to claim 3 by an additional control input of the DC/DC converter according to Figure 3, with which an external alternator charge controller of the battery can stop an overcharging of the battery by an external source at the jump start connection. 11. Diagnostic capability of the arrangement according to claim 1 by extending the arrangement by a diagnostic circuit with an interface to the vehicle bus system in order to be able to transmit information about the battery charge state and battery symmetry to a higher-level central computer.