Integrated meter in an electric vehicle supply equipment (EVSE)

An integrated meter in an electric vehicle supply equipment (EVSE) is described. Input power is received at input terminal of the EVSE and carried through a conductor that passes through an opening of a current transformer coil of the meter. The input power is split into a main path and an auxiliary path. The main path is for charging an electric vehicle (EV). The auxiliary path provides power to the meter to the EVSE itself. The auxiliary path passes through the opening of the current transformation coil in a reverse direction before being passed to a power supply of the meter and to a power supply of the EVSE to remove any current not for charging the EV from current measurements. The meter calculates energy measurements that do not include current drawn by the meter and the EVSE and transmits them to a processor of the EVSE.

FIELD

Embodiments of the invention relate to the field of electric vehicle supply equipment (EVSE); and more specifically, to an integrated meter in an EVSE.

BACKGROUND

Electric vehicle charging stations, sometimes referred to as EVSE, are used to charge electric vehicles (e.g., electric battery powered vehicles, gasoline/electric battery powered vehicle hybrid, etc.). An EVSE commonly includes a switchable relay to control charge transfer for an electric vehicle. Some EVSEs include a measuring device to measure current, voltage, power, power factor, and/or energy accumulation. Such a measuring device is sometimes referred to as a meter.

Meters may be required to be compliant with certain directives or standards. An example of such a directive is the Measuring Instruments Directive (MID) 2014/32/EU. A meter included in an EVSE in the European Union may need to be approved as MID compliant. A conventional EVSE that requires MID compliant metering typically uses one of the following implementations. One approach is to use a MID compliant meter that is typically DIN rail mounted and connected through the main wiring either upstream of the product or within the housing of the product. Another approach is to submit the entire EVSE for MID compliance approval.

SUMMARY

An integrated meter in an electric vehicle supply equipment (EVSE) is described. In one aspect, the integrated meter can be used for calculating energy measurements for charging an electric vehicle. Input power is received at input terminals of the EVSE and carried through a conductor that passes through an opening of a current transformer coil of the meter. The input power is split into a main path and an auxiliary path. The main path is for charging an electric vehicle (EV). The auxiliary path provides power to the meter to the EVSE itself. The auxiliary path passes through the opening of the current transformation coil in a reverse direction before being passed to a power supply of the meter and to a power supply of the EVSE to remove any current not for charging the EV from current measurements. The meter calculates energy measurements that do not include current drawn by the meter and the EVSE and transmits them to a processor of the EVSE.

In another aspect, the integrated meter can be used for calculating energy measurements in a vehicle-to-grid (V2G) environment where energy is transferred from an electric vehicle to the grid. Input power is received from an electric vehicle and carried through a conductor that passes through an opening of a current transformer coil of the meter. A first part of the power path is for providing power to the grid (V2G). A second part of the power path provides power to the meter and the EVSE itself. The second part of the power path passes through the opening of the current transformation coil before being passed to a power supply of the meter and to a power supply of the EVSE. The meter calculates energy measurements that include the power sourced from the electric vehicle. The power used by the EVSE and the meter is not subtracted from these measurements.

DESCRIPTION OF EMBODIMENTS

An EVSE that includes an integrated meter is described. The meter is assembled into the EVSE without any manual wired connections. Current for charging an electric vehicle (EV) passes through openings within the meter without being electrically connected to the meter. Low power mains AC data connections are made through connection terminals between the meter and the circuit board within the EVSE. The meter may be used for bidirectional metering (power to an EV, and power from an EV).

The meter is in a location within the circuitry of the EVSE such that the power for the EVSE, meter, and for charging an EV (or from the EV), runs through current coil(s) of the meter. To account for only the current being drawn by the electric vehicle, the meter includes an auxiliary loop that runs backwards through the current coil(s) and then to the power supply of the meter and the power supply of the EVSE. This allows for any non-EV current to be removed from the meter measurements. All power required for the internal power supply of the meter and for the power supplied to an auxiliary power output on the meter are passed through this auxiliary loop. The auxiliary power output is used to power the functions of the EVSE. The auxiliary power pin may be enclosed within the secured housing of the EVSE to prevent abuse.

Unlike conventional off the shelf meters that are DIN rail mounted that require manual wired connections, the meter described herein does not require a manual wired connection. Assembly is therefore easier and faster compared to these conventional meters. Further, the meter may be submitted for approval or compliance independently of the EVSE. Once approved, it can be assembled into the EVSE. This reduces the complexity of the approval process as compared to approving the full EVSE. For instance, if the full EVSE must be submitted for approval, it may be required to be manufactured in an approved facility. Further, the complete unit may require extensive end of line testing where any failures can cause the entire product to be reworked.

FIG.1illustrates an exemplary system that uses an integrated meter according to an embodiment.FIG.1illustrates an EVSE105that includes a charging unit110and a dock150. The charging unit110includes a meter module120, a power supply unit142, a processor140, and relays145. The power supply unit142, the processor140, and the relays145are used for providing charging functionality for an EV such as the EV160. The term relay as used herein includes contactors and/or other types of suitable electrically operated switches. Other components may also be included in the EVSE105and/or charging unit110such as a receptacle, circuitry for a wired EV charging connection, circuitry for a wireless EV charging connection, a charging cable, communication modules (e.g., wired or wireless communication), safety modules, display, and/or external lights.

The meter module120includes all the electronics to provide energy measurements for the charging unit110. The meter module120can also provide voltage, current, and/or power measurements. The meter module120transmits the measurements to the charging unit110(e.g., through a digital interface). In an embodiment, the meter module120is compliant with a measurement standard or directive such as the MID2014/32/EU. Unlike conventional off the shelf meters, the meter module120does not have terminals for wired connections and is assembled into the charging unit110without any manual wired connections. This allows the meter module120to be installed faster and easier compared to conventional meters.

The meter module120includes a meter power supply unit (PSU)123, a processor124, an analog to digital converter (ADC)126, a data connector127, an auxiliary power in connector128, an auxiliary power out connector129, and current transformer (CT) coils130,131, and132. The data connector127connects to the processor140of the charging unit110. The data connector127is used as the interface for communicating energy readings (kWh) and optionally current, voltage, and/or power measurements to the charging unit110. The auxiliary power in connector128connects to the ADC126, the meter PSU123, and the auxiliary power out connector129. The auxiliary power out connector129connects to the power supply unit142of the charging unit110. The charging unit110may include other components such as a display, an LED, an isolation component, or other components. The data connector127, the auxiliary power in connector128, and the auxiliary power out connector129may be implemented with pogo pins (spring contacts that connect with a pad on the opposing board) or board-to-board connectors.

The dock150is where the AC field wiring connections are made to an external power source. The power source may supply, for example, 400 VAC/480 VAC, 3 phase. The power source may be a power grid. The dock150includes input terminals for connecting to the external power source. As illustrated inFIG.1, the dock150includes an L1input terminal151, an L2input terminal152, an L3input terminal153, a neutral input terminal154, and a ground input terminal155. The dock150can accept directly connected field wiring to the input terminals. Alternatively, the dock150may be configured with a plug for connection into a pre-wired outlet. During assembly, the charging unit110is fitted with the dock150. AC power is passed through the dock150to the charging unit110.

In the case of metering EV charging, the main current from the external power source passes through openings of the meter module120that are surrounded by the current transformer coils130,131, and132. A main path of the current is used for charging the EV160and an auxiliary path of the current is used to power the internals of the meter module120and the components of the charging unit110that are not directly sending power to the connected EV160.FIG.1shows the main path as illustrated with three main loops (loops136,137, and138) that pass through the current transformer coils130,131, and132(from the L1input terminal151, L2input terminal152, L3input terminal153respectively), where the direction of the current flows toward the EV160.FIG.1also shows the auxiliary path which passes through the auxiliary power in connector128. The auxiliary power in connector128is electrically connected to the L1input terminal151, L2input terminal152, L3input terminal153, and neutral input terminal154. The auxiliary path includes three loops (loops133,134, and135) that pass through the current transformer coils130,131, and132in the opposite direction as the main path (e.g., the direction of the current flows towards the meter PSU123and the PSU142through the auxiliary power out connector129). As shown inFIG.1, only the L1line is being passed to the auxiliary power out connector129due to power needs of the charging unit110(if the power needs were greater, L2and/or L3could also be passed through the auxiliary power out connector129).FIG.1shows three phases being passed to the meter PSU123, however there may fewer phases being passed (e.g., one or two) depending on the PSU. Voltage, current (and therefore power), and data are passed between the meter module120and the charging unit110through board-to-board connections that are made once the meter module120is installed. For example, the auxiliary power in connector128is used for passing voltage to the ADC126for voltage measurements, for passing power to the meter power supply unit123, and for passing power through the auxiliary power out connector129to the power supply unit142of the charging unit110. The auxiliary power out connector129is used for passing power for powering the power supply unit142of the charging unit110. Data is passed through a low voltage data interface (the data connector127) that can be used by the meter module120for communicating measurements including energy measurements.

FIG.2shows the exemplary system ofFIG.1in the case the meter is being used for metering from the EV to an external source (e.g., V2G). In such a case, the main current from the EV160passes through the openings of the meter module120that are surrounded by the current transformer coils130,131, and132. A first part of the path of the current is used to supply power to the external source and a second part of the path of the current is used to power the internals of the meter module120and the components of the charging unit110.FIG.2shows the first part of the path as illustrated with three main loops (loops136,137, and138) that pass through the current transformer coils130,131, and132, where the direction of the current flows toward the L1input terminal151, the L2input terminal152, and the L3input terminal153respectively.FIG.2also shows the second part of the path which passes through the auxiliary power in connector128. The auxiliary power in connector128is electrically connected to the L1input terminal151, L2input terminal152, L3input terminal153, and neutral input terminal154. The second part of the path includes three loops (loops133,134, and135) that pass through the current transformer coils130,131, and132towards the meter PSU123and the PSU142through the auxiliary power out connector129. Unlike the case of vehicle charging, in the case the meter is being used for metering from the EV to an external source, the direction of the first and second part of the path are the same. As shown inFIG.2, only the L1line is being passed to the auxiliary power out connector129due to power needs of the charging unit110(if the power needs were greater, L2and/or L3could also be passed through the auxiliary power out connector129).FIG.2shows three phases being passed to the meter PSU123, however there may fewer phases being passed (e.g., one or two) depending on the PSU. Voltage, current (and therefore power), and data are passed between the meter module120and the charging unit110through board-to-board connections that are made once the meter module120is installed. For example, the auxiliary power in connector128is used for passing voltage to the ADC126for voltage measurements, for passing power to the meter power supply unit123, and for passing power through the auxiliary power out connector129to the power supply unit142of the charging unit110. The auxiliary power out connector129is used for passing power for powering the power supply unit142of the charging unit110. Data is passed through a low voltage data interface (the data connector127) that can be used by the meter module120for communicating measurements including energy measurements.

The meter module120is in a location within the circuitry of the charging unit110such that the power for the charging unit110, the meter module120, and for charging the EV160or for receiving power from the EV160, runs through current coil(s) of the meter module120. However, in the case of charging the EV160, any output to the auxiliary power out connector129to the charging unit110and to the meter module120itself (e.g., to the meter PSU123) is first passed backwards through the current transformer coils130,131, and132(e.g., the loops133,134, and135) to ensure that the resultant measured current is for only what is passed to the EV160itself and not the background power of the meter module120or the charging unit110. Current consumed by the charging unit110and the meter module120(as opposed to current consumed by an EV connected to the EVSE) is not measurable by the meter module120. In the case of receiving power from the EV160, the output to the auxiliary power out connector129to the charging unit110and to the meter module120itself (e.g., to the meter PSU123) is passed in the same direction through the current transformer coils130,131, and132(e.g., the loops133,134, and135) as the main loops (loops136,137, and138). In this case, the meter module120measures all the current provided from the EV160. Thus, the power used by the EVSE and the meter module120itself is not subtracted from the energy measurements.

The meter module120performs current and voltage measurements and transmits them via a digital interface (e.g., the data connector127) to the charging unit110. For example, the current transformer coils130,131, and132transform high current to low current that can be measured by the ADC126as a voltage. The ADC126converts the analog voltage values from the current transformer coils130,131, and132into digital values. The processor124combines the raw values to calculate the final current measurements. For voltage measurements, the ADC126converts the analog voltage values received from the connection to the auxiliary power in connector128to digital values. The processor124combines the raw values to calculate the final voltage measurements. To create energy measurements, the processor124multiples the current and voltage measurement in real-time to create a power measurement. The processor124accumulates the power measurements over time to create an energy measurement. The ADC126can also include any upstream conditioning of the inputs (e.g., filters, voltage dividers). The processor124causes the measurements (e.g., the energy measurements, current measurements, voltage measurements, and/or power measurements) to be transmitted to the processor140through the data connector127.

The meter module120may store information including metering and/or measured data. For instance, the meter module120may include physical memory that stores information such as the current measurement, voltage measurement, power measurement, and/or energy measurement. The information can be signed (e.g., by the meter module120) and transmitted to the charging unit110. In addition to, or in lieu of signing the data, the data can also be encrypted before transmitting to the external component.

The meter module120may be submitted for approval or compliance (e.g., MID compliance) independently of the charging unit110. Once it is approved, it can be installed into the EVSE. In an embodiment, the housing surrounding the meter module120may provide tamper protection. For instance, the tamper detection may detect if the meter module120is opened. The tamper detection can take the form of a tilt sensor, light sensor, infrared sensor, acoustic sensor, a lead seal, or a sticker. In an embodiment, detection of a tamper attempt can trigger erasure of data on the meter module120. The meter module120may be calibrated and sealed in the factory.

FIG.3shows an exemplary EVSE310that includes the meter module120according to an embodiment andFIG.4shows the back side of the EVSE ofFIG.3. The form of the EVSE shown in the figures is exemplary and the meter module described herein can be included in different form factors of EVSE.

FIG.5shows one side of the meter module120andFIG.6shows another side of the meter module120according to an embodiment. The meter module120is included in a housing510. The housing510may provide tamper protection as described herein. Also shown inFIGS.5and5are the CT coils130-132. The CT coils130-132have openings through which the main current passes. The CT coils130-132are shown in a toroidal shape. However, the CT coils130-132can be in any magnetically valid shape including a square, rectangle, oval, or other closed loop shape.

FIG.6also shows the voltage and data connections (board-to-board)610that includes the data connector127, the auxiliary power in connector128, and the auxiliary power out connector129. AlthoughFIG.6illustrates a single housing that contains each of these connectors, in another embodiment the connectors may be located in separate housing or some combination of housings.

FIG.7shows an exemplary view of the EVSE ofFIG.3that shows some of the internal components of the EVSE. Not all the components of the EVSE are shown or described to not obscure understanding. The view ofFIG.7is without the meter module120being installed in the EVSE310(e.g., prior to the meter module120being installed). The input blades710,711, and712are electrically connected to the charger circuit board705that is part of the charging unit110. During assembly, the meter module120is fitted over the input blades710,711, and712(e.g., fitted such that the input blades710,711, and712pass through the openings of the current transformer coils130,131, and132). This allows the meter module120to perform current measurements without the current being electrically connected to the meter module120itself. Once in place, the meter module120is fixed such that the voltage and data connections are made with the charger circuit board705. AlthoughFIG.7shows input blades as the form factor of a conductor, other types of conductors may be used such as pin and barrels or wires.

FIG.8shows the same view of the EVSE asFIG.7and shows the meter module120installed in the EVSE310. The input blades710,711, and712are fitted in the openings of the current transformer coils130,131, and132respectively. The meter module120is fixed such that the voltage and data connections are made with the charger circuit board705.FIG.9shows the same view of the EVSE asFIG.8and shows the input blade connectors that are built into housings to create a connector910that mates with a plate of the EVSE310, shown more in detail inFIG.10that shows the connector910mounted to a charger mounting plate (the dock150) of the EVSE310and the AC input terminals1010. The AC input terminals1010include the L1input terminal151, L2input terminal152, L3input terminal153, neutral input terminal154, and the ground input terminal155.

FIG.11shows a cross-section of the charging unit110, the meter module120, and the dock150according to an embodiment. The input blade710is shown going through the opening of the current transformer coil130. Also shown inFIG.11is a current loop133. In the case of EV charging, the current loop133is an auxiliary loop where current runs backwards through the current transformer coil130and then to the meter PSU123and the power supply unit142of the charging unit110. In the case of receiving power from the EV, the current loop133carries current that runs through the current transformer coil130and then to the meter PSU123and the power supply unit142of the charging unit110in the same direction as the main loop. AlthoughFIG.11shows one current loop due to the cross-section, there is a separate current loop for each phase being measured and thus a separate current loop for the current transformer coils130,131, and132(the current loops133,134, and135). All power required for the internal power supply unit123of the meter module120and for the power supply unit142of the charging unit110are passed through these auxiliary loops. The current loops133,134, and135are within the envelope of the meter module120. Each current loop may be a wire that is carrying mains AC at low current. In a single-phase implementation, there may be only a single current loop.

In an embodiment, the current loops133,134, and135are integrated into the current transformer coils130,131, and132. For example, and as shown inFIG.11, the current loop133is integrated into the current transformer coil130(e.g., within the overmold (or potting) of the current transformer coil130). In another embodiment, the current loops133,134, and135are not integrated into the current transformer coils130,131, and132but are still within the envelope of the meter module120. For example,FIG.12shows a cross-section of the charging unit110and the meter module120where the walls of the meter housing510extend through the opening of the current transformer coil130and the current loop133is located outside of the current transformer coil130while still within the envelope of the meter module120.

FIG.13shows the power path overlay according to an embodiment. The embodiment inFIG.13is for the case of charging an EV. The power path includes a main path and an auxiliary path. The main path and the auxiliary path both include the input power1310passing from the AC input terminals through the input blades (e.g.,710,711, and712) and through the openings of the current transformer coils (e.g.,130,131, and132). The paths split where the main path passes towards the connected electric vehicle160and the auxiliary path passes towards the meter module120through low current connections (e.g., the auxiliary power in connector128). The main path also includes other components of the charging unit110such as the relays145.

The power of the auxiliary path passes to the meter module120through the auxiliary power in connector128and runs backwards through the current transformer coils130,131, and132, to the meter power supply unit123, and to the power supply unit142of the charging unit110through the auxiliary power out connector129. Thus, the auxiliary path feeds the meter power supply unit123and all EV charger functions that are not directly sending power to the connected EV160. The auxiliary path ofFIG.13ensures that the resultant current measured by the meter module120is for only what is passed to the EV itself and not the power of the meter module120or the charging unit110. To say it another way, the current entering the meter module120passes back through the current transformer coils130,131, and132thereby offsetting the current measurements and removing any non-EV current from the current measurements. The meter module120performs measurements (e.g., energy measurements, current measurements, and/or voltage measurements) and transmits them via a digital interface to the charging unit110.

The meter module120shown in the figures is designed to be used in a three-phase electrical system where there are separate current transformer coils for line1, line2, and line3. However, a similar meter module can be used in a single-phase electrical system. In a single-phase implementation, there may be only one current transformer coil and one input blade.

FIG.14shows the power path overlay according to an embodiment where power is being received from an EV (e.g., a V2G case). The power path includes a first part of the path and a second part of the path. The power path includes the input power1410passing from the connected electric vehicle160. The first part of the path passes toward the external power source (power to grid1420) through the openings of the current transformer coils (e.g.,130,131, and132) toward the AC input terminals through the input blades (e.g.,710,711, and712). The second part of the path passes towards the meter module120through low current connections (e.g., the auxiliary power in connector128). The first part of the path also includes other components of the charging unit110such as the relays145.

The power of the second part of the path passes to the meter module120through the auxiliary power in connector128and runs through the current transformer coils130,131, and132, to the meter power supply unit123, and to the power supply unit142of the charging unit110through the auxiliary power out connector129. Thus, the second part of the path feeds the meter power supply unit123and all EV charger functions that are not directly sending power to the connected EV160. The path ofFIG.14ensures that the resultant current measured by the meter module120includes all the current from the EV160. The meter module120performs measurements (e.g., energy measurements, current measurements, and/or voltage measurements) and transmits them via a digital interface to the charging unit110.

FIG.15is a flow diagram that illustrates a method for installing an integrated meter into an EVSE according to an embodiment. The operations ofFIG.15are described with respect to the exemplary embodiments of the other Figures. However, the operations ofFIG.15can be performed by different embodiments from that of the other Figures, and the embodiments of the other Figures can perform operations different from the operations ofFIG.15.

At operation1510, the meter module120is manufactured and tested as a standalone unit. The meter module120may be submitted for approval or compliance independently of the EVSE. This reduces the complexity of the approval process as compared to approving the full EVSE. For instance, if the full EVSE must be submitted for approval, it may be required to be manufactured in an approved facility. Further, the complete unit may require extensive end of line testing where any failures can cause the entire product to be reworked. In an embodiment, the meter module120includes tamper protection as described herein.

Next, at operation1515, the approved meter module120is assembled into the charging unit110. The assembly does not require any manual wired connections to be made. Assembling includes mounting the meter module120into the correct place over the input blades710,711, and712of the charger circuit board705as shown inFIG.8. Assembling also includes adding housing moldings that form the connector geometry. For example, the input blades710,711, and712are shrouded in plastic to create the connector910that mates with the charging mounting plate (e.g., the dock150).

Next, at operation1520, the charging unit110is fitted onto the charging mounting plate (e.g., the dock150) such as shown inFIG.10. Power can now be passed from the connection from the charging mounting plate to the input blades710,711,712of the charger circuit board705.

FIG.16is a flow diagram that illustrates exemplary operations for metering in an EVSE according to an embodiment. The operations ofFIG.16are described with respect to the exemplary embodiments of the other Figures. However, the operations ofFIG.16can be performed by different embodiments from that of the other Figures, and the embodiments of the other Figures can perform operations different from the operations ofFIG.16.

At operation1610, input power is received at input terminals of the EVSE. The input power may be received from a power source that is supplying, for example, 400 VAC/480 VAC, 3 phase. Next, at operation1615, the input power is carried through one or more conductors (e.g., the input blades710,711, and712) that passes through an opening of one or more current transformer coils (e.g., the CT coils130,131, and132) of the meter module120that is installed within the EVSE.

Next, at operation1620, the input power is split into a main path and an auxiliary path. The main path is used for charging the EV160and the auxiliary path provides power to the meter module120and provides power to non-EV charging functions of the EVSE that are not sending power for charging the electric vehicle. The current of the main path passes through the opening of the current transformer coil(s) (e.g., the CT coils130,131, and132) in a first direction (e.g., towards the EV). The auxiliary path passes through low current connections (e.g., the auxiliary power in connector128). The current of the auxiliary path passes back through the opening of the current transformer coil(s) (e.g., the CT coils130,131, and132) in a second direction (the reverse direction as the first direction) before being passed to a power supply unit123of the meter module120and before being passed to a power supply unit142of the EVSE. Because the current of the auxiliary path passes through the CT coil(s) in a reverse direction as compared to the current of the main path, and the current of the auxiliary path includes all non-EV charging current, the current sensed by the CT coil(s) only include the current that the EV consumes. Thus, any current not for charging the EV160is not included in current measurements from the CT coil(s).

Next, at operation1625, the meter module120calculates an energy measurement for charging the EV160. The meter module120measures current and voltage (where the current measurements do not include current that is not for charging the EV160), multiplies and integrates them to calculate the energy measurement. At operation1630, the energy measurement is transmitted from the meter module120to the EVSE (e.g., through the data connector127). Power measurements, voltage measurements, and/or current measurements may be transmitted from the meter module120to the EVSE (e.g., through the data connector127).

FIG.17is a flow diagram that illustrates exemplary operations for metering in an EVSE according to an embodiment. The operations ofFIG.17are described with respect to the exemplary embodiments of the other Figures. However, the operations ofFIG.17can be performed by different embodiments from that of the other Figures, and the embodiments of the other Figures can perform operations different from the operations ofFIG.17. In the embodiment ofFIG.17, an electric vehicle is using the EVSE to provide energy to an external power source.

At operation1710, input power is received from an electric vehicle connected to the EVSE. The input power may be received over a charging cable connecting the electric vehicle and the EVSE. Next, at operation1715, the input power is carried through one or more conductors (e.g., the input blades710,711, and712) that passes through an opening of one or more current transformer coils (e.g., the CT coils130,131, and132) of the meter module120that is installed within the EVSE. A first part of the power path is used to supply power to the external power source and a second part of the power path is used to provide power to the meter module120and provides power to non-EV charging functions of the EVSE. The current of the first part of the path passes through the opening of the current transformer coil(s) (e.g., the CT coils130,131, and132) towards the external power source. The second part of the path passes through low current connections (e.g., the auxiliary power in connector128). The current of the second part of the path of the auxiliary path passes through the opening of the current transformer coil(s) (e.g., the CT coils130,131, and132) in the same direction as the first part of the path before being passed to a power supply unit123of the meter module120and before being passed to a power supply unit142of the EVSE. Because the current of the first and second part of the path are in the same direction, the current sensed by the CT coil(s) includes the current received from the EV including current that is drawn by the meter and the EVSE.

Next, at operation1720, the meter module120calculates an energy measurement for the energy received from the EV160. The meter module120measures current and voltage multiplies and integrates them to calculate the energy measurement. At operation1725, the energy measurement is transmitted from the meter module120to the EVSE (e.g., through the data connector127). Power measurements, voltage measurements, and/or current measurements may be transmitted from the meter module120to the EVSE (e.g., through the data connector127).

Embodiments described herein refer to an AC EVSE. A similar meter module can be used if the EVSE supplies DC. In such an embodiment, the CT coils may be changed to DC current sensors such as hall effect or fluxgate sensors. On the AC side of a DC product a similar meter module can be used if the components are scaled for DC use.

Embodiments described herein include the reverse current loop(s) used for offsetting non-EV charging current in current measurements. In another embodiment, such a reverse current loop is not used. In such an implementation, the charging system may not offset the non-EV charging current in current measurements or use other ways of offsetting non-EV charging current.

In the preceding description, numerous specific details such as are set forth to provide a more thorough understanding. It will be appreciated, however, by one skilled in the art that embodiments may be practiced without such specific details. In other instances, control structures, gate level circuits, and/or full software instruction sequences have not been shown in detail to not obscure understanding. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.

While several embodiments have been described, those skilled in the art will recognize that the invention is not limited to the embodiments described and can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.