EP2595833A1

EP2595833A1 - High voltage supply system for a vehicle

Info

Publication number: EP2595833A1
Application number: EP11743467.0A
Authority: EP
Inventors: Robert Honzek; Andreas Szajek; Harald Dietel; Hans-Georg Hornung; Wolfgang Breu
Original assignee: AGCO International GmbH
Current assignee: AGCO International GmbH
Priority date: 2010-07-22
Filing date: 2011-07-14
Publication date: 2013-05-29
Also published as: GB201021969D0; GB201012269D0; WO2012010489A1; GB201021975D0

Abstract

A vehicle has a source (11) of electrical energy and an electrical outlet means (20) connected with the source via electronic control means (12) which provides both an AC and DC power supply to the outlet means. The source of electrical energy is an internal combustion engine (10) driving a generator (11) and the generator (11) provides an AC output which is converted by the control means (12) into a DC voltage which is supplied via a DC network (15) to one or more sets of terminals (30d, 30e:40d, 40e:50d, 50e) of the electrical outlet means (20). This DC network voltage also inverted (31, 41, 51) into an AC output which is supplied to one or more other sets of terminals (30a, 30b, 30c:40a, 40b, 40c:50a, 50b, 50c) of the electrical outlet means. In an alternative arrangement the source of electrical energy is a fuel cell and/or battery

Description

High voltage supply system for a vehicle

The invention relates to a high voltage supply system for vehicles, especially agricultural vehicles.

It is well know in the vehicle industry to provide electrical energy to power vehicle propulsion systems such as electric motors driving the vehicle wheels from, for example, rechargeable batteries, fuel cells or a combustion engine combined with a generator and associated battery.

Typically such a vehicle will, in addition to the propulsion system, also have an internal DC voltage network (12V or 24V) for supplying vehicle components and external systems such as trailer lights etc. Tractors differ considerably from trucks, vans and passenger cars as their primarily requirement is not simply to drive over the ground but to power attached implements such as trailers, balers, seed drills or ploughs etc. These implements include functions which are currently commonly powered by hydraulic systems or from a Power Take-Off (PTO) shaft driven from an engine of the vehicle. Such drives for attached

implements can be of constant speed type, e.g. to lift the boom of a sprayer, or of variable speed type, e.g. to drive a metering system of a seeder. Constant speed type drives may be today driven by the PTO shaft whilst variable speed type drives may be powered by hydraulics using regulators to vary flow and thereby speed of a fluid motor or ram. It is also known to power functions on a trailed implement by electric motors from an electrical supply on the towing vehicle. It is an object of the present invention to provide a vehicle, such as an agricultural vehicle and tractor, which can conveniently provide electrical power to functions on a trailed implement or other electrical consumers. Thus according to the present invention there is provided a vehicle having a source of electrical energy and an electrical outlet means connected with the source via electronic control means which provides both an AC and DC power supply to the outlet means. By providing both AC and DC power a wide range of implements and other applications can be catered for.

The source of electrical energy may be an internal combustion engine driving a generator.

In such an arrangement the generator is preferably an AC generator. An AC generator is chosen as it is more compact and efficient than a DC generator as it does not require brushes (which wear) nor a commutator ring (which causes sparking problems).

The AC frequency supplied by the generator is depending on the input speed (coming from the combustion engine).

In such an arrangement the AC generator output may be converted by the control means into a DC voltage which is supplied via a DC network to one or more sets of terminals of the electrical outlet means, this DC network voltage also being converted into an AC output which is supplied to one or more other sets of terminals of the electrical outlet means. This arrangement is adopted as, if a variable speed motor must be supplied, it is more efficient to take the DC network voltage and then convert this DC voltage in a DC/AC unit into AC at the required

frequency to give the required motor speed. This arrangement is especially useful if several motors with different speeds must be supplied from the tractor as the common DC network voltage can be converted into the appropriate AC required by each motor by respective DC/AC units. In an alternative arrangement the source of electrical energy may be a fuel cell and/or a battery.

The electrical outlet means may be divided into two or more branches, each branch offering AC and DC output simultaneously.

The AC and DC terminals of each branch may be connected with the respective AC and DC supply via respective power switches controlled by the control means to protect any consumer connected with the respective branch if a malfunction is detected. These switches are also provided to protect the tractor network in case of undue overload and to protect the operator against electrical shocks.

Alternatively, the electrical output means may be divided into two or more branches each branch being switchable between providing either an AC or a DC output.

One or more consumers carried by the vehicle may be supplied with DC output from the DC network. One or more consumers carried by the vehicle may also be supplied with an AC output independently of the electrical outlet means via a converter from the DC network. The invention will now described by way of example only with reference to the following drawing in which:

Fig.1 shows a dramatic scheme of a vehicle supply system according the present invention, and

Fig 2 shows a dramatic scheme of a second embodiment of the

invention.

Referring to Fig. 1 this shows a supply system 1 for a tractor 2 with front wheels 3 and rear wheels 4.

The system has a combustion engine 10, an electric generator 1 1 driven by the engine crank shaft 0a and an electronic power unit 12 (insulated- gate bipolar transistor) connected to the electric generator by wiring 1 1a.

The generator produces AC power with an AC frequency dependent on the combustion engine speed. The electronic power unit converts the AC power output of the generator 1 to a DC voltage with the defined DC- link voltage level to provide ail units connected to DC network 15.

A brake chopper 13 is provided to avoid a voltage rise in the DC network 15 if energy is fed back into the system from other sources than the generator. The chopper comprises an oscillating switch in series with a resistor and, depending on the input voltage overshoot (coming from e.g. the implement via the internal network) the switch is oscillated to guide the excess voltage into the resistor transforming the voltage into heat. The oscillation is necessary to keep the network active and supplying energy. If the switch was to be closed completely over a longer period, the complete voltage supplied by the system would be destroyed and all consumers would be non operative. By oscillating the switch, only the peaks of the voltage are destroyed and the system is still operative. In addition, the resistors are generally designed to be quite small so they are not capable of receiving a constant high load. Using oscillation enables them to cope with the load. E.g. the nominal voltage of the network is 700 V. The overshoot limitation is 900 V. If peaks of > 900 V occur the switch is closed in an oscillatory manner.

An insulation monitoring system 14 is provided to monitor the resistance in the network to detect electrical malfunctions in the medium voltage system. This is necessary to protect the life of potential users of the system and to prevent damage in electric components of the tractor or implement or other consumers connected to the system. Internal medium voltage DC network 5 (>400V, 150 kW) is provided for supplying tractor components such as a battery/supply network 16 via DC/DC converter 16a reducing voltage >400 V into, for example, the standard 12V supply. An electronic unit 17 for supplying a heating/ventilating/air conditioning (HVAC) compressor 17 via DC/DC converter 17a is also provided.

Similarly a variable cooling fan drive 18 is supplied via a DC/AC inverter 18a to provide a variable frequency to vary fan speed. To supply external consumers (e.g. on implements/ front loaders

/stationary devices supplied by the tractor) additional supply means are provided. For example, a first DC/AC branch 30 which includes an electronic unit 31 for inverting high power DC into high power AC at fixed frequency for the supply of one motor or other rotating device is provided. An

associated outlet terminal 20 is supplied from electronic unit 31 via a power switch 32 to deactivate the supply terminal connectors 30a, 30b, 30c.

In parallel, the DC network 15 is directly forwarded to the terminal 20 by branch 33 via switch 34 to deactivate DC supply from terminal DC connectors 30d and 30e .

A second DC/AC branch 40 and third DC/AC branch 50 are also provided with AC outlet outlets 40a-40c, 50a-50c and DC outlets 40d,40e and 50d,50e in terminal 20 exactly similar to DC/AC branch 30.

Branches 40 and 50 also have similar electronic units 41 and 51 , DC branches 43 and 53 and switches 44 and 54.

All branches 30, 40 and 50 are equipped with a potential equalisation function 60 in order to equalise potentials between different metal parts that can be touched simultaneously, or to reduce differences of potential which can occur during operation between the bodies of electrical devices and conductive parts of other objects. For example, the tractor stands on rubber tyres while the plough is contacting ground via steel parts. Thus, as the tyres and metal plough parts have different earthing properties and thus different electric potential, if the operator were to touch both simultaneously, the potential difference would pass through him and he could be injured badly.

As will be appreciated the above AC/DC supply system enables AC/DC electrical power to be provided simultaneously for a wide range

implements and other consumers.

Fig 2 shows an alternative embodiment in which most of the components are similar to those specified above in relation to Fig 1 and will not therefore be described again.

In the Fig 2 arrangement the internal high voltage DC network 15 is spread into four branches three of which, branches 60, 70 and 80 are again similar and thus only branch 60 will be described here.

First branch 60 with an integrated DC/AC and electronic unit 61 is provided to optionally : - invert DC into AC,

- adjust AC frequency in order to vary speed of electric drives

or alternatively

- pass DC to the terminals Depending on the requirements of the electric load connected to the terminals, either AC with variable frequency or alternatively DC can be provided. The electronic unit 61 is equipped with several connecting pins 61a to 61 h.

- Pins 61a, 61 b are provided for DC load

- Pins 61c, 61 d, 61 e are provided for AC load

- Pins 61f, 61 g, 61 h are provided for cutting off supply.

By means of switches 62 and 63, these pins 61a to 61 h are connected to terminal 200 which has connectors 200a, 200b, 200c. Branch 60 and the respective switches 62 and 63 are shown in a position in which AC only is supplied to terminal connectors 200a, 200b, and 200c.

The other branches 70 and 80 have similar electronic units 71 and 81 , switches 72,73:82,83 and pins 7 a to 71 h and 81a to 81 h which supply terminal connectors 200d, 200e, 200f, 200g, 200h and 200i.

Branch 70 and the respective switches 72 and 73 are shown in a position in which DC only is supplied to terminal connectors 200d, 200e, 200f. Branch 80 and the respective switches 82 and 83 are shown in a position in which no connection to terminal connector 200g, 200h, 200i is established, and no supply is provided. This can be used to prevent the user or external electric loads from danger in case of internal errors.

A fourth branch 90 is provided to supply low power (<5kW) AC supply for example a circular saw (for cutting wood) or pressure washer. These devices are normally driven by stationary home network, but by providing branch 90 such low power devices can also be used in the field/forestry. The DC/AC inverter 91 is supplying terminal connectors 200k, 200I, 200m. A protective earth is connected to terminal connector 200n and ground is connected to terminal connector 200o. This embodiment of Fig 2 enables the supply of either AC or DC in an optional manner by each branch 60,70 and 80 plus an extra supply branch 90 for low performance <5kW AC supply.

It is envisaged that the network could also contain many other internal consumers e.g. air compressors, water and cooling pumps driven by AC or DC voltages from the network. In the shown embodiments, the main energy supply is provided by a combustion engine driving a generator. It is envisaged that the main energy could also be provided by fuel cell, battery without departing from the scope of the present invention. Also, the combustion engine 10 may be used to drive the wheels 3 and 4 of the tractor or an electrical drive system may be employed.

Claims

1) A vehicle having a source (11 ) of electrical energy and an electrical outlet means (20) connected with the source via electronic control means (12) which provides both an AC and DC power supply to the outlet means.

2) A vehicle according to claim 1 in which the source of electrical

energy is an internal combustion engine (10) driving a generator (11 ).

3) A vehicle according to claim 2 in which the generator (11 ) provides an AC output which is converted by the control means (12) into a DC voltage which is supplied via a DC network (15) to one or more sets of terminals (30d,30e:40d,40e:50d,50e) of the electrical outlet means (20), this DC network voltage also being inverted (31 , 41 , 51) into an AC output which is supplied to one or more other sets of terminals (30a,30b,30c:40a,40b,40c:50a,50b,50c) of the electrical outlet means.

4) A vehicle according to claim 1 in which the source of electrical

energy is a fuel cell and/or a battery.

5) A vehicle according to claiml to 4 in which the electrical outlet

means (20) is divided into two or more branches (30, 40, 50), each branch offering AC and DC output simultaneously.

6) A vehicle according to claim 5 in which the AC and DC terminals of each branch (30, 40, 50) are connected with the respective AC and DC supply via respective power switches (32,34:42,44:52,54) controlled by the control means to protect any consumer connected with the respective branch, or the DC network, or any vehicle operator against electrical shocks.

7) A vehicle according to any one of claims 1 to 4 in which the

electrical output means is divided into two or more branches

(60,70,80) each branch being switchable (62,63:72,73:82,83) between providing either an AC or a DC output.

8) A vehicle according to any one of claims 3 to 7 in which one or more consumers (16,17) carried by the vehicle are supplied with DC output from the DC network.

9) A vehicle according to any one of claims 3 to 8 in which one or more consumers (18) carried by the vehicle are supplied with an AC output independently of the electrical outlet means (20) via an inverter (18a) from the DC network.

10) A vehicle according to claim 2 in which the internal combustion engine (10) is also used to drive the vehicle over the ground.

11 ) A vehicle according to claim 1 in which an electrical drive system is provided to drive the vehicle over the ground.