EP3968471B1

EP3968471B1 - An universal electric plug for residential dc and ac grids

Info

Publication number: EP3968471B1
Application number: EP20195387.4A
Authority: EP
Inventors: Oleksandr HUSEV; Indrek ROASTO; Roman SHEVCHENKO
Original assignee: Tallinn University of Technology
Current assignee: Tallinn University of Technology
Priority date: 2020-09-09
Filing date: 2020-09-09
Publication date: 2024-05-08
Anticipated expiration: 2040-09-09
Also published as: EP3968471C0; EP3968471A1

Description

Technical field

This invention belongs to the field of electric engineering and pertains to the concept of an electric facilities for residential DC and AC grids. More specifically, the invention concerns a universal electric plug.

Background art

Obvious trend of nowadays-electric grid is a growing interest to DC (direct current) grid. It is a well-known fact that AC (alternating current) voltage level can be easily stepped up or down by means of a transformer. The effective electrical energy distributed system can be constructed. However, recent works show that even a high-voltage DC-current distribution system is more effective than a high-voltage AC system. Due to the latest research efforts in power electronics, the high-voltage DC-current system may replace an AC system in the coming decades. The DC low-voltage distributed system may become a reality even sooner. Due to the simplicity of storage systems or renewable energy integration, reduction of power electronics stages in many devices that are connected to the conventional AC grid, this solution attracts discussion and research efforts towards implementation. At the same time, it is evident that transient from AC to DC grid cannot be done immediately. In the nearest decade, we will observe a merge of DC and AC systems.
The conventional AC low voltage sockets are well-known and is already specified and standardized, while DC sockets can be standardized based on existed inventions. This invention represents the concept universal plugs derivation for residential low voltage system. We want to propose a specification of the new universal plug that can be plugged in the conventional AC and new DC sockets.
This idea is based on the expectation that DC grid will be implemented in the future and will become an international standard based on asymmetrical socket.
Authors of the present invention have been analysed research literature, standards and patents. There are several types of the AC single-phase sockets that are specified by European standards. CEE 7 is a standard for AC plugs and sockets. First published in 1951 by the former International Commission on the Rules for the Approval of Electrical Equipment (IECEE), it unified standards produced by several continental European countries. The 2^nd edition was published in 1963 and last updated in March 1983. It remains available from the IEC, and is used in addition to IEC 60884-1.
The most common types of the AC sockets are called as Type F (or Plug F) and Type E. The plug Type F was designed in Germany shortly after the First World War. It goes back to a patent ( DE 370538 ) granted in 1926 to Albert Büttner, a Bavarian manufacturer of electrical accessories. It is round and has the addition of two grounding clips on the side of the plug. It defines size, distance between terminals and ground location. The AC system has alternating voltage polarity; as a result, it is unipolar and there is no difference in the terminals location of the AC plug. The CEE 7/7 plug was developed to work with Type E and Type F sockets. It has the grounding pin of the Type E socket and has grounding clips on both sides to work with Type F sockets.
DE 10 56 222 B discloses a universal electric plug as described in the preamble of claim 1. A DC plug is disclosed in US patent US8134254 "DC Power Outlets in Fixed Power Distribution Systems in or on Wall Installations". This patent describes a permanent charging station, where a variety of portable devices can be operated and/or re-energized in a home or office environment.
Another patent US7094089B2 describes a DC plug and a DC receptacle that are configured to engage one another at more than one position. The DC plug and DC receptacle are also configured with a small contact distance to minimize the insertion and extraction forces that occur between the DC plug and the DC receptacle.
Patent US5901056A "DC Power Supply Device Adapted To Operate With An Ac Power Supply Or With A Car Battery Wia A Cgarette Lighter" proposes a several solutions how to obtain DC power supply.
All of the above described solutions belong to the DC power supply for portable devices.
Document CN207234049U "A kind of new anti-mis-insertion power interface connector", granted by 13.04.2018 describes anti-mis-insertion power interface connector. The main idea consists in shape of the female connector. The butt end of the female connector housing is formed with can extend into the groove, and with the close-fitting docking section of the groove. When public connector and female connector dock, each male connector contacts conducting with corresponding female connector respectively. At the same time, the main drawback of the described solution that conventional plug that is adopted for Type F socket can be inserted in this female connector.
Similar idea but for electric AC 220 V grid is declared in the Yugoslavian patent YU54002A . It shows asymmetrical socket that can be used as a protection of opposite plugging.

Disclosure of the invention

The present invention proposes the new universal plug that can be plugged into conventional AC socket (Type F) and an asymmetrical power socket that can be used as DC socket. This asymmetrical DC socket has anti-mis-insertion power interface connector and protection from the AC plugs insertion.
Fig. 1a shows the conventional AC socket (Type F). The conventional AC socket has two 4.8 mm round socket openings for plug pins spaced 19 mm apart 1, it has two earth clips on the top and bottom sides 2 of the socket recess and a hole for screw fixing 3. The socket recess 4 shape is round (cylindrical). In addition, the socket recess has two grooves 5 in other two sides, i.e. one groove in one side, which defines the proper position of the male connector when plugged into AC socket.
Fig. 1b shows one the possible shape of the asymmetrical DC socket that can be installed instead or along with conventional AC socket in the building. The asymmetrical DC socket has similar earth clips on the top and bottom sides 2 of the socket recess and a hole for screw fixing 3. Similar to AC socket the asymmetrical DC socket has two 4.8 mm round socket opening 6, 7 for plug pins and spaced 19 mm apart but with direct current polarity that can not be swapped. The socket opening 6 and 7 have constant voltage difference that can be in a range from 340 V up to 450 V. In different to the AC socket the asymmetrical DC socket has protrusion 8 in one side of socket recess protruding into said recess which prevents plug connection with socket in the reverse way. Also instead of round shape of socket recess of the conventional AC socket the socket recess 9 of the asymmetrical DC socket has a square shape. However the socket recess of the asymmetrical DC socket can have different shapes, but in any case the shape of DC socket recess does not allow insertion of the conventional round AC plug.
Fig. 2 shows the conventional (Fig. 2a) and asymmetrical plugs (Fig. 2b). The asymmetrical DC plug has a correspondent to the asymmetrical DC socket (Fig. 1b) square shape with groove 10 corresponding to the protrusion 8 of the asymmetrical DC socket which defines connection of plug into socket and polarity of the protruding pins 11 and 12 that match the socket openings 6 and 7, of the plug female contacts in the asymmetric DC socket. This asymmetric DC plug can not be inserted in the conventional AC socket due to the different shape of recess of the conventional AC socket. The asymmetric DC plug has also grooves for grounding connectors 13. The electric cord (14) for all plugs is shown in Fig. 2.
Fig. 3 shows the proposed concept of the universal plug shape derivation 15 according to the embodiment of the present invention. The shape of body of the universal electric plug 15 is realised by the by the geometric intersection of the shape of the body of the AC plug 4 shown in Fig. 3a and the shape of the recess of the asymmetric DC outlet 9 shown in Fig. 3b. The crossing concept according to embodiment of present invention is illustrated in Fig. 3c.
As a result, Fig. 4 shows the proposed universal plug that can be inserted either in AC or DC sockets. The shape of the universal plug is round and diameter of the universal plug corresponds to the diameter of the round recess of the conventional AC socket and length of the side of the square of the asymmetric DC socket. The universal plug has two grooves for grounding 13 and groove 10 which defines placement and polarity of the protruding pins of universal plug when said plug is plugged to the asymmetric DC socket. At the same time, this universal plug can be connected to the conventional AC socket thanks to the shape of plug 15 that is derived by the geometric intersection of the shape of the body of the AC plug. This type of universal plugs can be utilized for devices that accept both DC or AC voltage grids.

Brief description of the drawings

Fig. 1a shows the conventional AC socket (Type F) as a reference socket;
Fig. 1b shows the asymmetrical DC socket;
Fig. 2a shows the conventional AC plug;
Fig. 2b shows the asymmetrical DC plug;
Fig. 3a shows the round recess shape of AC socket;
Fig. 3b shows the shape of the recess of DC asymmetrical socket;
Fig. 3c shows the crossing of the round recess shape of AC socket and the shape of the recess of DC asymmetrical socket;
Fig. 4 shows the proposed universal plug that can be connected to AC or DC plug;
Fig. 5 shows possible embodiments of the asymmetrical DC sockets along with shape of universal plugs.

Detailed description of the embodiments

The most important item of the asymmetrical DC socket concept is asymmetrical shape of the socket recess. It prevents wrong connection of the male plug taking into account voltage polarity of the DC grid. The universal plug shape embodiment are derived by the geometric intersection of the round shape of AC plug 4 and the corresponding embodiment shape of the recess of symmetrical DC socket.
The universal plug according to present invention has body comprising two protruding pins 11, 12 and two grounding grooves 13. The grounding grooves 13 are formed opposite in side of plug body as seen in Fig 4. The shape of the body of universal plug is derived by the geometric intersection of the shape of the body of the AC plug 4 and the shape of the recess of the asymmetric DC outlet 9.
Conventionally the cross section shape of grounding grooves 13 are square and the grooves are extending to the both end faces of the universal plug body. In addition the universal plug body can have groove 10 formed in the side of plug body. Said groove 10 is located in side of plug body on an axis parallel to the axis of the two grounding grooves 13. The groove 10 defines placement and polarity of the protruding pins 11, 12 of universal plug when said plug is plugged to the asymmetric DC socket. At the same time, this universal plug can be connected to the conventional AC socket thanks to the bevelled edges of the shape of plug 15 in other word to the shape of universal plug. This type of universal plugs can be utilized for devices that accept both DC or AC voltage grids.
Fig. 5 illustrates several different embodiments of the shape of the universal plugs that are highlighted by pattern fill. It may have square 9 shape of the recess and square protrusion only on the left side or only on the right side 16 as it is shown in Fig. 5a. Fig. 5b shows another embodiment where asymmetrical rectangular shape of the socket recess 18 is applied in order to prevent wrong plug connection without additional protrusion. As a result, the shape of the universal plug also will not have any grooves but due to the asymmetrical shape keeps the feature of the connection to the DC socket only by single way without possibility to reverse.
Fig. 5c shows another possible embodiment where more sophisticated recess 19 with protrusion can be used. Finally, Fig. 5d shows the embodiment with symmetrical recess and cut edges 20 and with protrusion 8 on the one side. Another important item of the DC socket concept is that an imaginary circuit 17 of the round recess of AC socket 4 can not be fitted into any of the above described asymmetrical DC sockets. The same is valid in a reverse way: the shape of the recess of the DC socket can not be fitted into the round recess of the AC socket.
The plugs of Fig. 2, Fig.5(b) and Fig.5(c) are only background embodiments and examples not forming part of the claimed invention (nor square sockets in Fig.5(b) and Fig.5(c)).

List of components

1 -two round pins spaced 19 mm apart;
2 - two earth clips on the top and bottom sides;
3 - the hole for screw fixing;
4 - the round shape of AC socket recess;
5 - two grooves that define the proper position of the male connector;
6 - the negative (positive) 4.8 mm round pin of the DC socket;
7 - the positive (negative) 4.8 mm round pin of the DC socket;
8 - the protrusion which prevents DC plug connection in the reverse way;
9 - the square shape of DC socket recess;
10 -the groove of the DC plug;
11 - the positive (negative) protruding pin of the DC and universal plugs;
12 - the negative (positive) protruding pin of the DC and universal plugs;
13 - the grooves for grounding connectors in the DC and universal plugs;
14 - the electric cord of the plugs;
15 - the shape of the universal plug derived by the geometric intersection of the shape of the body of the AC plug and the shape of the recess of the asymmetric DC outlet;
16 - the square protrusion which prevents DC plug connection in the reverse way;
17 - the imaginary circuit of the round recess of AC socket;
18 - the asymmetrical rectangular shape of the DC socket recess without protrusion;
19 - the asymmetrical not rectangular shape of the DC socket recess without protrusion;
20 - the symmetrical shape of the DC socket recess with protrusion and cut edges

Claims

A universal electric plug (15) having a plug body comprising two protruding pins (11, 12) to be inserted into outlet openings (1, 6, 7) of a conventional AC socket and of an asymmetrical DC socket and two grounding grooves (13) formed respectively on the top and bottom sides of the plug body and extending to both end faces of the plug body,
wherein a shape of the plug body is round and a diameter of the universal electric plug (15) is adapted to correspond to a diameter of a round recess (4) of the conventional AC socket, the universal electric plug can be plugged in the AC socket with possibility of reverse inversion by symmetrical shape of the AC socket,

characterized by an additional groove (10) formed only in the left side or only in the right side of the plug body, and

further characterized in that the additional groove (10) is defining a placement and polarity of the protruding pins (11, 12) when said plug is plugged to the DC socket, and a length of a side of a square of the asymmetric DC socket having a protrusion (8) in one side of its socket recess corresponding to the groove (10) and protruding into said recess which prevents the universal electric plug connection with the DC socket in reverse way, and the universal electric plug (15) can be plugged in the DC asymmetrical socket only by single way without possibility of reverse insertion by asymmetrical shape of the DC symmetrical recess (9) with the protrusion located only from the side of a positive or negative pin of the DC socket.
The universal electric plug according to claim 1, characterized in that the groove (10) forming any asymmetrical shape is located on an axis parallel to the axis of the two grounding grooves (13).