Scope of the invention
The present invention generally refers to electric distribution systems
for motorized vehicles and more specifically to those electric power supply and
distribution systems comprising two networks at different voltage levels, known
as dual voltage in the sector and hereinafter in this specification referred to
as DV, applied in an automobile.
The invention also refers to a method for implementing said system.
Such DV systems typically comprise a first network at 14 V used for
feeding low consumption loads, for example for lighting and supply of control signals,
usually fed in turn from the second network at a higher voltage, typically 42 V,
through a CC/CC electric converter or from a first battery B1. Said second 42 V
network is used for feeding high consumption loads such as the starter motor, heating
system, electromagnetic valve control, motors, such as those for the window control
mechanism, seat adjustments, fans, etc. and is fed from a generator G (the vehicle's
alternator) or from a second battery B2.
The invention is also applicable within the architectures implemented
in the automobile sector for achieving a sectorization of power, a principle according
to which a series of areas are defined in the vehicle, each one of which having
a smart node locally controlling the loads and the switches and detectors, sending
and receiving information through a multiplexed data bus, which allows for a large
reduction not only in the number of wires, but also in their length, not to mention
the decrease in the number of wires passing from one area of the vehicle to another,
whose parameter significantly acts upon the ease in wiring the assembly.
Background of the invention
DV systems for motorized vehicles have been disclosed in numerous
patent and patent application documents, it being possible to mention the following:
US 5,334,926, US 6,232,674, EP 337155, EP 539982, EP1033804, WO 99/22434 and WO
Also considered relevant for understanding DV technology is the document
by Joan Fontanilles, Jordi Giró, Javier Maixé et. al, "New requirements for
dual voltage CC/CC converter and power distribution system", United Technologies
Automotive MAI S.A. and Rovira Virgili University Electrical and Automatic Control
Engineering Department, Tarragona (Spain), published in the EAEC (European Automobile
Engineers Cooperation) Congress, Barcelona 1999.
British patent application GB 2,342,515 discloses a DV architecture
with two networks fed from respective batteries B1, B2, for a motorized vehicle,
which, in addition to the generally unidirectional classic CC/CC converter for feeding
the low voltage network from the higher voltage network, proposes the use of a second
bi-directional converter for controlling the status of charge of the two batteries
B1 and B2 for the purpose of adjusting the power flows between its inputs/outputs.
Said second converter is used when, in addition to normal operation (to feed the
lower voltage level network from the higher voltage level network), the low voltage
network is fed from the battery connected to the higher voltage branch, the higher
voltage network is fed from the two batteries B1, B2, or when the battery B1 feeding
the low voltage branch is charged from the higher voltage network.
Although the use of two shunted converters, as the latter document
discloses, is theoretically a feature it shares with the architecture proposed by
the present invention, the invention, as will be explained below, is generally based
on the use of more than two, one- or two-way CC/CC converters, and on a specific
way of controlling them to reach a singular purpose, which is the equalization of
the outputs of all the converters, the integration of said converter assembly within
a sectorial design for the vehicle's power, and a rating of said converters that
is below the requirements of the load set of the sector supplying each one of them.
This determines several operating conditions of the electric distribution system
where all CC/CC converters cooperate, all this non-existent in the technical guidelines
disclosed by said British patent application GB 2,342,515.
Brief description of the invention
The invention is thus based on an architecture in which the CC/CC
conversion between the two networks at different voltage levels is subdivided into
several shunted CC/CC converters, each one of them intended to supply a determined
load set of a sector of the automobile. As is well known, such CC/CC converters
are protected against short circuits consistent with the typical, characteristic
V-I curve (foldback curve), such that if a short circuit occurs in any load (not
controlled by a controlled switching device such as a SMART FET, relay or similar
device) affecting said CC/CC converter, the converter will protect the network by
setting the voltage to zero and not allowing the supply from the remaining loads.
It is evident that in this situation the fuses lose their specific role due to the
behavior of the CC/CC converter.
In order to prevent such drawback, according to the invention, the
arrangement of a plurality of CC/CC converters in shunted connection is proposed,
connected to a common point, whose point is likewise connected to the low voltage
battery which, in the case of a short circuit, will act on the grounded load's fuse.
In this manner, the power to be supplied is shared by the different converters into
which it has been divided and the battery which will supply current helping the
network if necessary is also shared.
In a preferred embodiment of the invention, in which the invention
shows its full potential, it has been foreseen that the different CC/CC converters
dynamically shift their working point in order to achieve the sharing of the same
current. For such purposes, a central control, for example according to a master/slave
architecture, whose control integrates a master microcontroller, will adjust the
different voltage values and the information of the intensity values required by
each load group at the expense of a corresponding CC/CC converter (acquired from
a detector or a tapping point for each load set) will be exchanged with said control
center using a CAN bus or the like.
Another feature of the invention is that each one of the converters
is intended to feed a series or set of differentiated loads located in different
areas of the vehicle, either in the highest voltage level network or in a network
at a lower level, according to the power sectorization principle explained above,
with the particularity that the CC/CC converters used have been designed such that
the power that each one of them can supply is less than that of the maximum consumption
of all said loads of the specific sector it feeds, such that the power supply to
each load set is carried out at specified times at the expense of at least more
than one of said different CC/CC converters. This follows the consideration that
generally, very rarely will consumption on the part of all the system loads, and
particularly of the different sectors, occur, which allows rating the converters
at a lower value than that which would be necessary considering a simultaneous and
continued consumption on the part of all the loads.
On the other hand, if several converters are connected at the same
point and have as a load, for example, battery B1 which feeds the low voltage network,
the power supplied by said battery can be divided by an n factor (depending on the
vehicle's number of CC/CC converters), such that the converters can be identical
and share the same output current. The battery will be responsible for supplying
the load for blowing out the fuses. But this architecture will also divide the power
conversion in whatever manner necessary.
For example, if a 500 W CC/CC converter is arranged in the vehicle's
compartment but its nearest loads require 600 W, the converter will begin to protect
itself by reducing the output voltage (according to a V-I curve of the converter
or typical foldback wave); at this moment, the nearest CC/CC converter with the
lowest connection resistance to the smart distribution node will supply the remaining
necessary power. In this manner, it can be said that, in a static state, the n CC/CC
converters used (for example 3, one for the motor compartment portion, another for
the passenger area, and a third one for the rear portion of the vehicle) will try
to share the same amount of power when the power required is close to the maximum
of each one of said CC/CC converters. In the eventual case that the maximum power
of all the converters is exceeded, then battery B1, or battery B2 where applicable,
will provide the remaining power required.
In a dynamic state (a high speed transient or power fluctuation) and
generally with frequencies greater than 100 Hz (for example, during a response to
abruptly opening or closing the windows, flashes of light, etc.), a master/slave
structure with microprocessor support is necessary so that all the CC/CC converters
share the same current. Due to all the CC/CC converters being located in different
areas of the vehicle, a bus, such as a CAN or VAN bus, can inform of the current
required by the loads and processed by the different CC/CC converters so that the
current can be shared in the face of transient phenomena. The speed of the bus and
that of the communication protocol controlled by the microprocessor are critical
factors, as well as detection method of the current, in order to configure the system
according to the proposal of this invention.
Such a configuration with several CC/CC converters will also allow
the converters to share the same thermal overloads due to dissipation, which can
To better understand the invention, a description thereof will be
given with reference to several sheets of drawings in which several embodiment examples
are shown, which are to be taken as merely illustrative and non-limiting of the
scope of the proposed technical guideline. For purposes of simplifying the explanation,
said drawings show two networks at different voltage levels, each one of them supporting
a series of sectorized loads associated with the output of a corresponding CC/CC
converter, although other arrangements, for example only with sectorized loads in
the lower voltage level branch, or with only a part of the loads of the upper voltage
branch sectorized, fall within the energy distribution system design being referred
Brief description of the drawings
Detailed description of several embodiment examples
- Figure 1 shows a schematic view of an architecture example according to the
principles of the present invention, with the loads to be supplied by the system
being distributed, and each set of loads being supplied by a converter.
- Figure 2 shows the known converter V-I curve (foldback curve) explaining the
protection against short circuits inherent to the converter, as a result of which
the converter will tend to rapidly protect itself, setting its output voltage to
zero against an intensity requirement greater than a certain level.
- Figure 3 shows an architecture with control of the working point of the different
converters from a control center according to the preferred embodiment of the invention
disclosed in the claims.
Figure 1 shows an electric distribution system in which a series of
loads Q1 to Q6 to be supplied are sectorized in a first higher voltage level network
r1, and specifically at 42 V, fed from a generator G (the vehicle's alternator)
and which supplies a starter motor S, as well as a lower voltage network r2, providing
14 V. A series of converters C1, C2, C3 are shunted between said two networks r1,
r2, with their outputs connected to a common point or output, fed from either of
said batteries B1, B2. Such an arrangement is determinant in order that, the different
converters C1, C2 and C3 being connected at the same point, and due to, for example,
battery B1 feeding the low voltage network as a load, the power supplied by said
battery B1 can be divided by a factor of 3, such that the converters C1-C3 can be
identical and share the same output current. The battery will be responsible for
supplying the load for blowing out the fuses. But this architecture will also divide
the power conversion as needed.
As indicated in figure 1, the 42 V higher voltage level network is
also connected to battery B2, to a generator G (the vehicle's alternator), and it
is foreseen for supplying a starter motor S.
Figure 2 shows a converter's typical V-I curve, or of protection against
short circuits, according to which if any load connected to the converter and not
protected by a controlled switching device, such as a SMART FET, relay or the like,
undergoes a short circuit affecting said CC/CC converter, the converter will protect
the network by immediately setting the voltage to zero and not allowing the supply
from the remaining loads. The shunted arrangement of converters C1, C2, C3 shown
in figure 1, connected at a common point to which one of the batteries B1 or B2
is also connected, solves this drawback because the battery acts by blowing out
the grounded load's fuse, and the power to be supplied is thus shared by the different
converters C1, C2, C3.
In the lowest voltage branch of the loads, several loads have been
schematized in the first group, being necessary to understand that their protection
can be accomplished by fuses, by controlled switching devices such as SMART FET,
or by a combination of both systems.
According to the preferred embodiment of the invention shown in figure
3, it has been foreseen that the CC/CC converters shift their working point in order
to share the same current, for which purpose a central control M will adjust the
different voltage ratings in the nodes to which the respective outputs of the CC/CC
converters C1, C2, C3 are connected, and the information regarding the intensities
required in each one of said nodes will be exchanged using a CAN bus, for example.
More specifically, it has been foreseen that the system be implemented in a master/slave
architecture in which said control center M integrating the microprocessor establishes
itself as master and each one of the converters C1, C2, C3 as slave. Several detectors
D1, D2, D3 have been provided for collecting the current required in either of the
outputs of each CC/CC converter C1, C2, C3, whose information is sent to the control
center, where the microcontroller has, for example, a management algorithm loaded
into a suitable, programmable memory for distributing the power to be supplied among
the different CC/CC converters C1-C3 for the purpose of achieving an equalized output
from them. Thus, all the CC/CC converters used can be equal (in their modular design
principle, leading to reduced manufacturing costs) and, for example, with a power
that is lower than that of the load set to be supplied, as indicated in the figures
given in this example.
For a full implementation of the disclosed electric power distribution
system, with sectorized loads in both networks r1 and r2, it is necessary that at
least two of the converters C1-C3 are two-way converters.
Although the arrangement shown in the embodiment example described
up to this point with three converters C1, C2, C3 has been designed for a sectorization
of the loads of an automotive vehicle in the front portion or motor area, the passenger
area, and the rear portion or trunk, which may result to be very convenient, the
loads can be sectorized very differently in practice, in a smaller or larger number
of groups and also use a smaller or larger number of CC/CC converters.