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Title:
A SYSTEM AND METHOD FOR RECHARGING AN VEHICLE ELECTRIC WITH DIRECT CURRENT
Document Type and Number:
WIPO Patent Application WO/2019/202540
Kind Code:
A1
Abstract:
Described is a system (100) for recharging an electric vehicle (V) with direct current, comprising a main recharging device (200), said main recharging device (200) comprising main energy storage means (3); a main DC/AC converter (2); a single DC/DC converter (6), at least one main control unit (14) connected at least to said main energy storage means (3), said recharging system (100) also comprising an auxiliary device (110) connected to the main DC/AC converter (2) of said main recharging device (200), said auxiliary device (110) comprising secondary energy storage means (30), a connection to a public electricity grid (R), a secondary DC/AC converter (20) and a secondary control unit (40) connected to said main control unit (14) and to said secondary energy storage means (30).

Inventors:
DE LAURI, Mauro (Milano, 20124, IT)
GOZZI, Luigi (Milano, 20124, IT)
Application Number:
IB2019/053214
Publication Date:
October 24, 2019
Filing Date:
April 18, 2019
Export Citation:
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Assignee:
ALFAZERO S.P.A. (Via Vittor Pisani 16, Milano, 20124, IT)
International Classes:
B60L53/30; B60L53/10; B60L53/53; B60L53/55; B60L55/00; H02J3/32; H02J7/34
Domestic Patent References:
WO2015134851A12015-09-11
Foreign References:
CN103248064A2013-08-14
US20110276194A12011-11-10
CN205657439U2016-10-19
Attorney, Agent or Firm:
ZERMANI, Umberto (Viale Lancetti 17, Milano, 50132, IT)
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Claims:
CLAIMS

1. A system (100) for recharging an vehicle electric (V) with direct current, comprising a main recharging device (200), said main recharging device (200) comprising:

main energy storage means (3);

a main two-way DC/AC converter (2) having a direct current section (2a) connected to said main energy storage means (3) and an alternating current section (2b) which can be connected to a local power source (G) or to a public electricity grid (R);

a single two-way DC/DC converter (6) having a first direct current section (6a) which is connected both to the main energy storage means (3) and to the continuous current section (2a) of the main DC/AC converter (2), and a second direct current section (6b) which can be connected to said electric vehicle (V) for powering it, at least one main control unit (14) connected at least to said main energy storage means (3), the recharging system (100) being characterised in that it also comprises an auxiliary (1 10) connected to said direct current section (2a) of the main DC/AC converter (2) of the main recharging device (200), the auxiliary device (1 10) comprising secondary energy storage means (30), a connection to a public electricity grid (R), a secondary DC/AC converter (20) having a direct current section (20a) connected to the secondary energy storage means (30) and an alternating current section (20b) which can be connected to a public electricity grid (R) and a secondary control unit (40) connected to the main control unit (14) and to the secondary energy storage means (30).

2. The recharging system (100) according to claim 1 , wherein said main control unit (14) is configured to monitor the state of charge of said main energy storage means (3) and to send a relative signal to the secondary control unit (40) of said auxiliary device (1 10).

3. The recharging system (100) according to any one of the preceding claims, wherein said secondary control unit (40) is configured for electrically connecting at least a first (31 ) of said secondary energy storage means (30) with the continuous current section (2a) of said main DC/AC converter (2) of the main recharging device (200).

4, The recharging system (100) according to claim 3, wherein said secondary control unit (40) performs the electrical connection between at least said first (31 ) secondary energy storage means (30) with the continuous current section (2a) of the main DC/AC converter (2) when it receives a signal from the main control unit (14) relative to the running out of the charge of said main energy storage means (3).

5. The recharging system (100) according to claim 4, wherein said secondary control unit (40) monitors the state of charge of said first (31 ) secondary energy storage means (30) and is configured to disconnect from the direct current section (2a) of the main DC/AC converter (2) when the charge of the first secondary storage means (31 ) runs out.

8. The recharging system (100) according to claim 5, wherein said secondary control unit (40) of said auxiliary device (1 10), after the charge of the first secondary storage means (31 ) runs out, is configured to perform the electrical connection between at least a second (32) means of secondary energy storage with the continuous current section (2a) of the main DC/AC converter (2) of the main recharging device (200).

7. The recharging system (100) according to any one of the preceding claims, wherein said main DC/AC converter (2) of the main recharging device (200) is configured for:

- converting an electrical signal acquired from the continuous direct current section (2a) into an alternating current electrical signal provided by the alternating current section (2b);

- converting an alternating electrical signal acquired from the alternating current section (2b) into a direct current electrical signal provided by the direct current section (2a).

8. The recharging system (100) according to any one of the preceding claims, wherein the main recharging device (200) also comprises an ON/OFF switching device (7) connected to the alternating current section (2b) of said DC/AC converter (2) and connectable to the public electricity grid (R).

9. The recharging system (100) according to any one of the preceding claims, wherein the second direct current section (6b) of the DC/DC converter (6) is of the type with a variable voltage in order to adapt to the voltage (V) of the battery of the electric vehicle.

10. A method for recharging an electric vehicle (V) with direct current by means of the recharging system (100) according to any one of the preceding claims, comprising the steps of:

- converting an alternating current electrical signal into a direct current electrical signal through the main DC/AC converter (2) of said main recharging device (200) and storing the direct current electrical signal in the main energy storage means (3);

- converting an alternating current electrical signal into a direct current electrical signal through the secondary DC/AC converter (20) of the auxiliary device (1 10) and storing said direct current electrical signal in the secondary energy storage means (30),

- converting the direct current electrical signal stored in the main energy storage means (3) into another direct current electrical signal through the DC/DC converter (6), and making available said other direct current electrical signal to the electric vehicle (100) through the second direct current section (6b) of the DC/DC converter (6),

- upon reaching the running out of the charge of said main energy storage means (3) of said main recharging device (200) converting the direct current electrical signal stored in the secondary energy storage means (30) into another direct current electrical signal through the DC/DC converter (6), and making available the other direct current electrical signal to the electric vehicle (100) through the second direct current section (6b) of the DC/DC converter (6).

Description:
DESORPTION

A system and method for recharging an vehicle electric with direct current

Technical field

This invention relates to a system and a method for recharging an electric vehicle with direct current.

In particular, the invention can be used in the home/residential contexts, or in an industrial context, both private and public.

Background art

The storage of electrochemical energy in emergency applications, for example in Uninterruptible Power Supply units (UPS) has been known for some time.

Most recently, the diffusion of plants for the production of energy from renewable sources, such as photovoltaic units and wind turbines, has set the basis for the development of a“smart” electricity distribution network - commonly known as a“smart grid” - which, in addition to the centralised generation of electricity, operates alongside a distributed generation thanks to a plurality of peripheral nodes, even small in size, from which the energy flows are two-way (from the centre towards the nodes and from the nodes towards the centre).

Since, due to their very nature, the renewable sources cannot be programmed, the distributed generation requires a more complex control system, which is able to dynamically control (that is to say, in real time) the energy excesses of certain nodes, storing energy in suitable devices and/or redistributing it towards other nodes with a deficit, and which is able at the same time to adjust the centralised generation.

Subsequently, the saturation of the energy market and the consequent cuts to incentives to use renewable sources has increasingly led to self consumption, so that each peripheral node maintains itself, storing the energy surpluses in order to reuse them during low or zero production periods. This approach allows an increase in the independence of the nodes from the central grid and the adoption of so-called“peak shaving solutions, that is to say, which avoid the use of the grid during the periods of maximum request.

Figure 1 illustrates the block diagram of a known control system 1 for the storage of energy (typically but not necessarily electrochemical), which schematically illustrates the division between a direct current/voltage DC domain and an alternating current/voltage AC domain.

The fundamental element of the system 1 is a two-way inverter 2, that is to say, a static DC/AC converter from direct DC domain to alternating AC domain, and vice versa.

The alternating current coming from the public electricity grid R and/or from local devices G for generating electricity (for example, renewable sources and/or motor generators) powers one or more alternating current user devices U and, in the case of excess, is sent to the two-way inverter 2 to be converted into direct current and stored in an accumulator 3, for example a battery.

The system 1 also comprises an ON/OFF switching device 7 interposed between the two-way inverter 2 and the public electricity grid R.

During periods of poor power availability from the grid G, the flow reverses: the direct current is supplied by the battery 3, which feeds the two-way inverter 2, which then feeds the various user outlets U with alternating current.

The common recharging devices of electric vehicles are connected to the alternating current AC domain (that is, they act as an alternating current user U).

For example, patent document US 2012/206104 proposes a recharging system of the vehicle with alternating current, through the connector 23, which picks up energy directly from the distribution unit AC. The DC/DC converter 213, on the other hand, is not used for powering the vehicle but only for picking up energy from the vehicle. It should be noted that one of the main brakes to the diffusion of electric vehicles - in addition to the cost - is linked to the lengthy waiting times for recharging: several hours compared with just a few minutes for nor a! internal combustion engine vehicles.

This is also due to the fact that the alternating current battery chargers have a limited output, as is limited the power available in a residential context.

According to the prior art, there are also electric vehicles with the recharging system directly in direct current.

Figure 2 illustrates the block diagram of a recharging system 10 in direct current of an electric vehicle V, according to the prior art.

The division is also schematically illustrated between the direct current/voltage DC domain and the alternating current/voltage AC domain. Apart from the elements present in the system 1 of Figure 1 , the recharging system 10 of Figure 2 also comprises a static AC/DC converter 4, which receives alternating current from the public electricity grid R and/or from local devices G for generating electricity (for example, renewable sources and/or motor generators) or from the electrochemical accumulator 3 using the two-way inverter 2 and transforms it into alternating current to be stored directly in the battery installed on the vehicle V.

On the electric vehicle V there is a connector which makes it possible to directly connect the relative battery to perform the recharging in direct current.

Therefore, in this case, the limit of the flow of power towards the electric vehicle V is defined by the lower power between battery 3, static converter AC/DC 4, two-way inverter 2 and power available from the grid R or from the local generation G.

In this way, the times for recharging an electric vehicle reduce from a few hours to 15-20 minutes, thereby becoming comparable with the times for recharging vehicles with an internal combustion engine. The main drawback of this solution is linked to the need for high power from the local and/or public grid and the need to increase the size of the two-way inverter (which is the main cost item of the system together with the battery) to satisfy high power requirements for medium-long periods of time (for example, greater than 5 minutes), thus making the system unusable in the home/residential context.

For example, the document WO 2011/078397 proposes a feed system for an electric vehicle comprising a plurality of DC/DC converters, wherein attention is focused on the DC/DC converter indicated with numeral 15. The converter, which is one-way, has the sole purpose of converting the voltage supplied by the battery 52 to a predetermined output voltage value.

The only AC/DC converter 16 is one-way; in effect it is configured for converting the inlet AC (from the supply 100) to outlet DC.

The recharging system of the vehicle comprises a double conversion stage, with relative loss of efficiency at each step. For example, fin order to recharge the battery 52 from the grid 100 use is made of the AC/DC converter 16 and the DC/DC converter 15. For the recharging of the vehicle use is than made of the DC/DC converter 21 (which is one-way). In fact, the two-way design in WO 201 1/078397 has been obtained by using two DC/DC converters: number 21 which picks up energy from the line 12 and directs it to the vehicle and number 22 which picks up energy from the vehicle and directs it on the line L1.

Disclosure of the Invention

In this context, the technical purpose which forms the basis of this invention is to provide a system and a method for recharging an electric vehicle with direct current which overcomes the above-mentioned drawbacks of the prior art.

In particular, the aim of the invention is to provide a system and a method for recharging an electric vehicle with direct current which allow a rapid recharging also in situations with limited power availability. A further aim of the invention is to provide a system and a method for recharging an electric vehicle with direct current which simplify the control of the recharging from the user side, reducing waiting times and increasing the availability of recharging sites, for example in the home/residential context or in public/private parking areas.

Another aim of the invention is to provide a system and a method for recharging an electric vehicle with direct current which are much as possible independent from the grid, thereby avoiding an increase in the price of energy.

The technical purpose indicated and the aims specified are substantially achieved by a system for recharging an electric vehicle with direct current comprising:

- energy storage means, for example one or more electrochemical batteries or one or more capacitive accumulators or one or more kinetic accumulators;

- a two-way DC/AC converter having a direct current section connected to the energy storage means and an alternating current section which can be connected to a local power source or to a public electricity grid;

- a DC/AC converter having a direct current section connected to the energy storage means and a second direct current section which can be connected to the electric vehicle to power it.

Preferably, the DC/DC converter is of a two-way type. The first direct current section of the DC/DC converter is also connected with the direct current section of the DC/AC converter.

Preferably, the recharging system comprises an ON/OFF switching device connected to the alternating current section of the DC/AC converter and connectable to the public electricity grid.

Brief description of the drawings

Further features and advantages of the invention are more apparent in the non-limiting description of a preferred but non-exclusive embodiment of a system and a method for recharging an electric vehicle with direct current, as illustrated in the accompanying drawings, in which:

- Figures 1 and 2 illustrate, respectively, block diagrams of an energy storage system and of a system for recharging an electric vehicle, according to the prior art;

- Figure 3 illustrates the block diagram of a system for recharging an electric vehicle with direct current, according to the invention.

With reference to Figure 3, the numeral 100 denotes a system for recharging an electric vehicle V with direct current, in particular for use in the home/residential context, or in industrial contexts, both public and private.

The recharging system 100 comprises a main recharging device 200 and an auxiliary device 1 10 electrically connected to each other.

The main recharging device 200 comprises a main two-way DC/AC converter 2 (or two-way inverter) having a direct current section 2a and an alternating current section 2b.

Figure 3 schematically illustrates the division between a direct current/voltage DC domain and an alternating current/voltage AC domain. The main DC/AC converter 2 is configured for:

- converting the direct current electrical signal acquired from the direct current section 2a into an alternating current electrical signal provided by the alternating current section (2b);

- - converting the alternating current electrical signal acquired from the alternating current section 2b into a direct current electrical signal provided by the direct current section 2a.

In this context, the term “electrical signal” is used to mean a signal representing an electrical quantity, such as current or voltage.

The main recharging device 200 comprises main energy storage means 3. Preferably, the energy storage means 3 comprise one or more electrochemical batteries, for example connected in parallel.

For example, the batteries 3 are lead-acid or lithium-ion or nickel metal hydride batteries.

Alternatively, the main energy storage means 3 comprise one or more capacitive accumulators or one or more kinetic accumulators.

The direct current section 2a of the main DC/AC converter 2 is connected with the main energy storage means 3.

The alternating current section 2b can be connected to a local power source G, such as, for example, a renewable electricity source (photovoltaic unit, wind turbine, etc.), or a motor generator.

The main recharging device 200 comprises a main control unit 14 connected at least to the main energy storage means 3 to control the state of charge.

The main control unit 14 is advantageously connected to all the components of the main recharging device 200.

The recharging system 100 also comprises an auxiliary device 1 10 connected to the direct current section 2a of the main DC/AC converter 2. Advantageously, the auxiliary device 1 10 is located in a residential or industrial room different from that where the main recharging device 200 is located and it is connected to the same by means of norma! electrical wiring.

The auxiliary device 1 10 comprises secondary energy storage means 30 and a connection to a public electricity grid R.

The secondary storage means 30 may comprise one or more batteries 31 , 32, 33 preferably having the same characteristics as those of the main storage means 3.

The auxiliary device 1 10 also comprises a secondary DC/AC converter 20 having a direct current section 20a connected to the secondary energy storage means 30 and an alternating current section 20b which can be connected to a public electricity grid R.

The auxiliary device 1 10 also comprises a secondary control unit 40 connected to the main control unit 14 of the main recharging device 200 and the secondary energy storage means 30. The main recharging device 200 also comprises an ON/OFF switching device 7 (of known type) connected to the alternating current section 2b of the main DC/AC converter 2 and to the public electricity grid R.

The main recharging device 200 also comprises a DC/DC converter 6 having a first direct current section 6a and a second direct current section 6b, the aim of which is to convert the DC voltage of the energy storage means 3 to a DC voltage suitable for the battery of the vehicle V.

The second direct current section 6b is preferably of the type with a variable voltage in order to adapt to the voltage of the battery of the vehicle V.

The first direct current section 6a is connected with the energy storage means 3, whilst the second direct current section 6b can be connected to the electric vehicle V for powering it.

Preferably, the DC/DC converter 6 is also of a two-way type.

As well as with the main energy storage means 3, the first direct current section 6a of the two-way DC/DC converter 6 is also connected with the direct current section 2a of the DC/AC converter 2 and the auxiliary device 1 10.

Advantageously, moreover, the main control unit 14 of the main device 200 is configured to monitor the state of charge of the main energy storage means 3 and to send a signal to the secondary control unit 40 of the auxiliary device 1 10.

Preferably, the secondary control unit 40 is also configured for electrically connecting at least a first means 31 of storage of secondary energy storage with the direct current section 2a of the main DC/AC converter 2 of the main recharging device 200.

Advantageously, moreover, the secondary control unit 40 performs the electrical connection between at least the first means 31 of storing secondary energy with the direct current section 2a of the main DC/AC converter 2 when it receives a signal from the main control unit 14 relative to the running out of the charge of the main energy storage means 3. The secondary control unit 40 also monitors the state of charge of the first means 31 for secondary energy storage 30 (and advantageously also of the subsequent means 32, 33 .) and is configured to disconnect from the direct current section 2a of the main DC/AC converter 2 when the charge of the first secondary storage means 31 runs out.

Advantageously, moreover, the secondary control unit 40 of the auxiliary device 1 10, after the charge of the first secondary storage means 31 runs out, is configured to perform the electrical connection between at least a second means 32 of storage of secondary energy with the continuous current section 2a of the main DC/AC converter 2 of the main recharging device 200.

The method for recharging an electric vehicle with direct current, according to the invention, is described in more detail below.

During periods of excess energy coming from the local power source G or from the public electricity grid R, the main DC/AC converter 2 of the main recharging device 200 converts the alternating current electrical signal acquired from its alternating current section 2b into a direct current electrical signal, which is stored in the main batteries 3 (or, more generally speaking, in the main storage means)

In the same periods of excess energy coming from the public electricity grid R, the secondary DC/AC converter 20 of the auxiliary device 1 10 converts the alternating current electrical signal acquired from its alternating current section 20b into a direct current electrical signal, which is stored in the batteries 30 (or, more generally, in the secondary storage means).

The energy stored in the main 3 and secondary 30 batteries is used to recharge, as necessary, the electric vehicle V by means of the DC/DC converter 6, with a flow of power from the first direct current section 6a to the second direct current section 6b.

The DC/DG converter 6 is, according to the invention, the only component designed for the flow of a high power towards the vehicle V. In particular, once the control unit 14 of the main device 200 determines that the main battery 3 has run out, it is configured for communicating and controlling the secondary control unit 40 in such a way that the latter enables the electrical connection between the secondary batteries 30 and the vehicle V being recharged.

Basically, by means of this connection there is a plurality of batteries (3 and 30) connected in sequence to the vehicle V.

Moreover, during periods with low energy production, it is the main battery 3 or the secondary batteries 30 which provide a direct current electrical signal to the direct current section 2a of the DC/AC converter 2, which converts it into an alternating current electrical signal, made available to one or more user devices U by means of the alternating current section 2b.

If the two-way type DC/DC converter 8 is used, the energy may also be picked up by the electric vehicle V (in particular by its battery) using the second direct current section 6b and providing the local network G or the user outlets U through the DC/AC converter 2 (with flow of power from its direct current section 2a to the alternating current section 2b).

The ON/OFF switching device 7 is able to communicate to the other elements of the recharging system 100 (e.g. to DC/AC converter 2, to the energy storage means 3, to the DC/DC converter 6, to the energy generator if present etc.) a signal representing the presence/absence of the grid.

This communication may take place by means of known radio technologies, such as Bluetooth, ZigBee, Wi-Fi or by transmission of data on power networks (for example, the so-called “power line communication”).

In response to this signal representing the presence/absence of the grid, each element of the recharging system 100 sets predetermined parameters for that state.

Even in the event of a grid power failure (black-out) it is therefore possible to continue powering the user devices U.

For example, in the event of a power grid failure, it is possible to limit and/or defer the activities of alternating current user devices U with particularly high energy consumption (for example, ovens, dishwashers, washing machines, etc.) or it is possible to set limitations to the drawing of power from the batteries 3 by the DC/AC converter 2 or the DC/DC converter 6.

The features of a system and a method for recharging an electric vehicle with direct current, according to the invention, are clearly described above, as are the advantages.

In particular, the recharging system proposed allows a rapid recharging of the electric vehicle with direct current also in situations with limited availability of power both from local generation and from the public grid. The system is substantially independent from the grid and operational even in the case of a black-out.

The proposed recharging system can also be used in the home/residential context, therefore contributing towards increasing the confidence of the user towards electric vehicles.