TECHNICAL FIELD

This relates to chargers and charging systems for electrically operated vehicles. It has application to apparatus/circuitry connecting (i.e. connected between) an AC power grid to such vehicles, including for connection to the interior of such vehicles such as the vehicle battery, charge capacitors and chassis. It also has application to a method of operating and controlling such apparatus/circuitry.

BACKGROUND OF THE INVENTION

In known systems, there are state of the art chargers which include effective isolation between the AC supply/grid side and the vehicle battery/charge capacitor side. Typically, such isolation is provided by a transformer. The effects caused by an applied AC grid are considered insignificant since the involved circuitry has a small physical size and there are low parasitic effects.

There is a trend toward non-isolated charger systems, i.e. without transformers.

AC grid effects have a larger effect on these systems and the system must compensate for those effects in both directions, from outside to inside and from inside to outside. So, the number of parasitic elements is higher. There is a need to provide compensation of those effects, to react to them and counteract the parasitic effects such as leakage currents cause by fluctuating voltages in the vehicle power wiring.

The compensation mechanisms circuitry and methods must cover a wide spectrum defined by various capacitors involved in onward filtering stages and AC voltages in charging and vehicle systems.

There are relatively small effects with three phase charging and medium effects with split phase charging. Single (one phase) charging can either come with small effects when neutral line is connected as expected. One sub-version of the one phase charging under Mode 4 (inverted Mode 2) can however cause a need for very substantial compensation the moment the phase is swapped with neutral and the supposed quiet line carries the grid frequency to its full amplitude into the capacitors between chassis and power lines in the vehicle.

So inverted Mode 2 provides problems and risk. Any compensation network between the apparatus and the vehicle (inside) may not sufficiently cope with dynamics of LI on the nominal N net (line). This is because there is a sine way of amplitude 400V (pp)on the line. The safe design for compensation amplifier aligned with VDA320 and is set to 58 V (pp) max. In the prior art also, there is a recommendation to detect inverted Mode 2 (Mode 4) and flag a message e.g. to alert the user by adequate HMI interface.

In most countries, connection to an AC supply is by means of a well-defined plugs type. Most operate a 2-phase 240V AC supply. In the UK there is a 2-phase system with live, neutral and earth lines which are clearly set in terms of plug and terminal lay out and orientations. In Continental Europe there are AC supply systems of a similar type, but the plug and sockets terminals may have a defined live and neutral, represented provided by two pins in the plugs/connectors, as well as optionally an earth. These may also be defined in terms of orientation. In some cases, there are also “convenience chargers” which may comprise plugs with two pins (and e.g. a central earth) which can be inserted in two orientations into the socket and respective recesses. So, in one orientation a terminal pin #1 is connected to a Live connection (e.g. LI) and the other pin# 2 to the neutral connection, and in a second orientation (rotated by 180 degrees) the pin #1 is connected to neutral and pin #2 to the live. SUMMARY OF THE INVENTION

In one aspect is provided An electrical vehicle charger including a first terminal connected to a first terminal line and a second terminal connected to a second terminal line, and including a first nominally live input line and second nominally neutral input line, said input lines connected to further charging circuitry or vehicle connection terminals of said charger, and adapted such that the first terminal line is selectively electrically connectable to either the first or second input lines and the second terminal line is selectively electrically connectable to either the first or second input lines.

Said first and second terminals may be formed in a plug.

The electrical vehicle charger including means to detect the voltage on one or both of said terminals.

An electrical vehicle charger may include: first switch means electrically connected between said first terminal line and said first input line; second switch means electrically connectable between said second terminal line and said second input line; third switch means electrically connected between said first terminal line and said second input line; and, fourth switch means electrically connectable between said second terminal line and said first input line.

An electrical vehicle charger is preferably adapted such that on connection of the first terminal to a live supply line, said first switch is closed and said third switch is open.

The electrical vehicle charger may be adapted such that on connection of the second terminal to a neutral supply line, said second switch is closed and said fourth switch is opened

The electrical vehicle charger may be adapted such that on connection of the first terminal to a neutral supply line, said first switch is open and said third switch is closed. The electrical vehicle charger may be adapted such that on connection of the second terminal to a live supply line said second switch is open and said fourth switch is closed.

Said input terminals may be electrically connected to a charger power stage.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

- Figure 1 shows a prior art system;

- Figure 2 shows a simplified figure of the prior art arrangement and shows those parts of the circuitry relevant for explanation of the invention;

- Figure 3 shows an example of the invention;

- Figure 4 shows a typical vector diagram of a 3 -phase power grid, illustrating aspects of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows a prior art system. There are shown four terminal lines in the example. Line A is referred to as supplying connections LI, LI, LI, N; line B is referred as supplying connections to L2, L2; line C supply connection L3; and line D as supplying N, N, N, LI as will become clear below.

The letter “L” refers to a “live” (line) in a phased supply/grid, and the letter “N” to neutral. There may be threes live lines LI, L2, L3 in a 3 -phase system and two (LI L2) in most domestic AC supply grids. The left-hand side inputs show the possibilities of connections on the terminal lines. The following table shows the terminal lines. The columns thus define various input possibilities, shown in figure 1 as PI, P2, P3 and P4.

PI P2 P3 P4

Line A LI LI LI N

Line B L2 L2

Line C L3

Line D N N N LI

Line, A and line D are mandatory (i.e. will always be there). Line D is the nominal neutral or quiet line. The output which can be regarded as input line to the power stage, at 1 is the centered DC bus /line pair which signal is filtered. This is electrically connected/coupled in conventional systems to Line D. This is nominally neutral .

The terminal lines are fed through filter stage 2 which comprises e.g. individual inductors. This is then fed to a second filter stage 3 again with individual inductors. Reference numeral 4 shows a voltage reading block, reference numeral 5 shows a block which reads (differential) current and which has optionally also the function of injecting current for compensation purposes. Block 6 shows a command discontinuity device which may e.g. control relays (shown by block 7) and can be deactivated. In traditional systems it is usual for a transformer to be used downstream. This generally would have isolation properties that means the fluctuation of current in the vehicle itself would not be seen. However, with non-isolation systems there is no transformer so there is proper linking of the internal s of the vehicles with grid. T31 is the chassis group. Depending on the vehicle here chassis quite different.

Possibility P3 is often referred to as Mode 2 and possibility P4 is referred to as “inverted mode 2”. With reference to the centered DC bus/line pair - this is filtered. AC lines feed the rectification stage with a positive rail, a negative rail and a center point that enables the symmetry of the positive and negative power stages. Generally, there is a pair of capacitors (not shown) from the lines to chassis. What these capacitors do is conserve currents. The center point of the rectifier is connected to the low noise neutral. In the possibility P4 (inverted Mode 2), the quiet neutral line 1 is no longer quiet and there are fluctuations in the current on this line. This appears as a fault current but is not the case. It is preferable to hide the effects of this; e.g. regarding effects on vehicle or on the grid

In other words, there are examples where the plug for convenience charges may be plugged in either way round and so the quiet (nominally neutral line 1) may be connected to LI (or L2/L3). This is referred to a phase swapping. Where the swapped live and neutral are swapped back from one another. If this is the case LI means the line 1 is pulled up and this results in fluctuations in the current. Thus, for inverted mode 2 the quiet line (nominally neutral line) is live and this results in current fluctuations in the filter capacitor current which as mentioned would otherwise require compensation for this leaky current So, a problem is there is a requirement for complex large compensation drives which have negative implications such as: component size and stress, power dissipation, and difficulties with discriminating small error currents from leakage currents. Figure 2 shows a simplified figure of the prior art arrangement and shows those parts of the circuitry relevant for explanation of the invention. On the left-hand side is shown the power source e.g. AC grid for which a charger connection to a vehicle is electrically connected/connectable, designated generally by reference numeral 10. Reference numeral 11 shows portion of circuitry of the charger (terminal end) that is the portion of the charger connectable to the AC supply. So, circuitry 11 is electrically connected/connectable to other portion of the charger which is connected or connectable ultimately to the vehicle itself on the right side and on the left side to the power supply. The grid has connection terminals 12 a and 13a connectable to corresponding terminals 12b* and 13b* respectively of the charger which are connected to terminal lines 12b and 13b.

In a first mode (mode 2) equivalent to Possibility P3 above terminal 12b* and line 12b is connected to a live terminal LI; and terminal 13b* and line 13b connected to a neutral terminal N. In the inverted mode 2, terminal 12b* and line 12b are connected to a neutral terminal N; and terminal 13b* and line 13b connected to a live terminal LI. The charge includes a Vac pre-relay interface 14 which has connections to the lines of respective terminal 12b, 13b. Linesl2b and 13b are also connected respectively to relays 15 and 16 of relay block 17. The outputs of these (19 and 20) respectively are input to the main power stage of the charger. In addition is a relay command interface which can control operation of the relays 15 and 16.

Line 20 is the nominal quiet or neutral line equivalent to line 1 of figure 1. However, when line (terminal) 12b is connected to neutral N and line (terminal) 13b connected to a Live line (LI), the line 20 becomes live and is no longer neutral or “quiet”.

So, under normal conditions, line 12b is connected to live and 13b to neutral. In phased swapped conditions, line 12b is connected to neutral and 13b connected to live. So, to recap when the charger is supplied in the figure as shown at the left side of the figure via a power source. PE, N and L are relevant. There is a set of voltage monitoring interfaces. Upon detecting power and upon request from other control devices, the relays are commanded to make a galvanic link and feed the power to the main power stage. Relay 15 and relay 16 are both closed for operation. Invention

In examples, circuitry is provided which treats i.e. rectifies the inverted supply/phase swapped situation. A switch configuration/matrix is used to e.g. revert the swapped line and neutral back to the favorable arrangement not needing the augmented systems for compensation of resulting parasitic effects.

Figure 3 shows an example of the invention. The figure is like figure 2 and like components have the same reference numerals.

The circuitry includes additional connections (31,32) between the lines 12b and 13b as well as additional relays/switches (33, 34), such that if the circuitry detects a swapped phase condition, the input of connection 12b can be connected to line 10 and input of connection 13b can be connected to line 19.

So, in figure 3 is shown an alternative switch matrix bloc 30 which includes the relays 15 and 16 as before. In addition, line 12b is connected to line 20 via an additional connection 31 which includes switch/relay 34 and line 13b is connected to line 19 via an additional connection 32 which includes switch/relay 33.

In mode 2, terminal /line 12b and 13b is connected to live LI and neutral respectively. Line 12b is connectable to line 19 via closing of relay switch 15 as before, and line 13b is connectable to line 20 via closing of relay 16 as before. Relays/switches 33 and 34 are open.

In inverted mode 2, on detecting that line 12b is connected to neutral and 13b to live, relays 15 and 16 are switched to open and during charging switches/relays 33 and 34 are closed. In this way the line input connection to line 12b is switched back (electrically connected) to the nominal live line 19 and the input connection 13a is switched back (electrically connected) to the nominal neutral (quiet) line 20 So, to recap, there is a set of voltage monitoring interfaces. Upon detecting power and upon request from other control devices, the relays are commanded to make a galvanic link and feed the power to the main power stage. Relay 15 and relay 16 are both closed for operation when LI and N are in the “normal” order and relays 33 and 34 are open. Relay 33 and relay 34 are closed when N and LI are in the inverted order and relays 15 and 16 open.

The decision mechanism is using the voltage measurements and may apply a further criterion asking what line is electrically identical or nearer to PE. The one that is nearer is detected as the neutral line and is routed to the preferred input on the power stage. The other one is the AC line and is routed to the noise tolerant input on the power stage.

It is necessary to determine the connection mode (e.g of the charger plug) and for this the voltages on lines 12b and or 13b are determined by associated circuity.

Figure 4 shows a typical vector diagram of a 3 -phase power grid where the two phases L2 and L3 are not connected to form a MODE 2 charging supply; unconnected L2 and L3 are shown by large black crosses. Reference 101 shows the range for neutral (N), reference numeral 103 shows the range for LI. In

MODE 2 the grid supplies protective earth (PE), Neutral (N) and one phase (LI) by a plug. The position in the plug of PE is guaranteed. The positions of N and LI can be interchanged arbitrarily. For N and L coming in on the foreseen line arrangement, the noise in the system relative to PE is minimal. This is favored case. For N and L coming in swapped, the noise in the system is increased. The figure shows the illustration with a triangle and a circle and a cross show the relationship of the power lines LI L2 L3 and the neutral line and the protective earth that is derived from the neutral line. The protective earth (PE) is an imperative connection and links the chassis and the measurement reference of the controller to the grid. Therefore, it is possible to define the expected area shown by the circle in which the neutral voltage by amplitude and phase angle is, simply by reading the lines A through D in relation to chassis/ PE. In case N and L were swapped, the decision in favor of the more appropriate line to center the charger to is in the area and the inappropriate line is outside of that circle 102.

In examples of the invention the incoming voltage is measured relative to PE and a decision is made about what line is going to be used on what input of the power stage. As illustrated, the line closest to PE reference point marked by the cross 101 is attributed the role of neutral. In case the incoming line pair is swapped, the product reverts this situation by additional switches to select automatically the better configuration (least noise created)

In examples of the invention, in phase swapping, the frequency defining line is replaced by neutral and the system is back to a quiet voltage on the capacitors.

The implementation used in examples is a set of one or two relays/switches that support together with the power stage, the routing of the power according to the best configuration. The extra switching arrangement/matrix enables use of a lesser compensation circuit or the tolerance to a larger number of parasitic capacitors and filter capacitors between the power lines and chassis in the vehicle. It makes the system safer as detection of fault currents is less obfuscated be leakage currents. The difference with regard the invention is that there is provided a switching matrix/circuitry comprising a series of switched/relays designated generally by reference numeral 13. These relays can be controlled to switch the inputs and the lines 19 and 20 as so respective inputs to the filter stages.