Methods and apparatuses for determination of ev insulation status for safety operations

Abstract

Method and apparatus for measuring electrical parameters of an EV for determination of insulation parameters. The method comprises establishing data communication with the EV so that the vehicle is switched into a power exchange mode, the power exchange mode being a battery charging mode or a power export mode; measuring battery terminal voltages of the EV with respect to the electrical chassis of the EV via the power exchange port; and processing the battery terminal voltages, which are voltages measured with respect to the electrical chassis of the EV to determine isolation resistance and / or insulation status of the EV.

Description

METHODS AND APPARATUSES FOR DETERMINATION OF EV INSULATION STATUS FOR SAFETY OPERATIONSField

[0001] The present disclosure relates to methods and apparatuses for obtaining electrical insulation parameters of live parts of vehicles having a high-voltage electrical system, and more particularly to methods and apparatuses for determining electrical insulation of electrical vehicles for operational safety.Background

[0002] Electrical vehicles have become a major type of on-road vehicles running worldwide.

[0003] Among the different types of electrical vehicles, the rate of growth of battery electrical vehicles, EV or BeV in short, is perhaps amongst the highest. BeV is a type of electrical vehicles that is equipped with an on-board stored energy source to provide electrical energy to operate its prime mover, which may comprise a single traction motor or a plurality of traction motors.

[0004] A BeV needs to be charged (or recharged) from time to time so that the on-board stored energy source can be replenished with fresh energy after the stored energy has been spent, for example, due to energy dissipation as a result of operation of the traction motor(s) and / or other accessories such as heaters or air-conditioners.

[0005] In order to enable a BeV to operate with a reasonable drive range, for example, a range comparable to that of conventional fossil fueled vehicles, an on-board stored energy source of a BeV would need to have an energy storage capacity of at least 30kWh, while higher energy storage capacities such as 50kWh, 80kWh, 100kWh, 120kWh or higher are not uncommon.

[0006] Batteries are currently the most practical option for use as on-board energy storage devices of BeV, and battery cells are typically connected in parallel and in series to form battery assemblies in order to meet the operating voltage and stored energy capacity requirements.

[0007] The battery assembly of an average BeV has a nominal voltage rating of 300V and above, and the current trend is to have a higher voltage rating of 800V and above in order to deliver a higher power to the traction motor at a lower current, since heat dissipation I2R is dependent on the square of working current.

[0008] As an example, Model Y® of model year 2024 has a battery assembly having a nominal voltage of 357V, a nominal energy capacity of 78.1 kWh, and a 400V electrical system architecture.

[0009] However, operation of a vehicle at a high voltage such as 300V, 500V and above would mean the requirement of a compatible high-voltage electrical system, and electrical insulation would inevitably become a major safety factor of concern to users, passengers and authorities alike.

[0010] With the current trend of increasing the high-voltage electrical systems of EV to 1000V DC or more, due insulation of the live parts of the high-voltage electrical systems is a safety important factor for ensuring operational safety, because defects in insulation of the live parts of the high-voltage electrical systems may cause arc faults and / or electric shocks. Arc faults in EV can cause damage to the associated cables and equipment, as well as burning of the entire EV in a short time.

[0011] The high-voltage electrical circuits of EV, especially the circuits which form the traction system, for example the high voltage live parts of the circuits interconnecting the battery assembly and the traction motor, are part of a closed system which is mostly sealed and even multiply sealed due to operational safety concerns or requirements, and this would mean that the high voltage live parts are not accessible. As a result, the insulation statuses of the electrical circuits are difficult, if not impossible, to evaluate and / or determine.

[0012] It is trite that insulation of electrical power systems such as the high-voltage electrical systems of EV, especially their high-voltage traction systems, deteriorates with time, for example, due to prolonged exposure to heat generated during traction operations and weathering. Therefore, it would be useful to be able to evaluate and / or determine the insulation status of EV, especially the insulation status of the high-voltage live parts of the EV, from time to time to promote operational and user safety. The document E / ECE / 324 / Rev.2 / Add.99 / Rev.3-E / ECE / TRANS / 505 / Rev.2 / Add.99 / Rev.3 dated 23 March 2022 published by the United Nations (“UN Document”) provides a useful guide for measuring isolation resistance of EV and the document as well as definitions therein are incorporated herein by reference.

[0013] However, it is well known that the high-voltage live parts of EV are a closed system which is heavily sealed, guarded and protected, and is almost impossible to access from outside of the EV unless closed system is dismantled or partially dismantled to remove the sealing, guarding and / or protection, but it is trite that dismantling or partially dismantling with subsequent re-assembling have adverse side effects and are not desirable for safety and / or durability.

[0014] It is desirable to have methods and / or tools to assist with determination of vehicle insulation parameters without the need to dismantling an EV or its battery assembly to promote safe operations of BeV.Disclosure

[0015] An EV such as a BeV herein has an on-board rechargeable electrical energy storage system (“REESS”) which is an energy storage source configured as a stored energy source such as a battery assembly to provide operation power including traction power to the EV.

[0016] An EV is configured to perform power exchange operations and comprises a power exchange port which is configured to facilitate power exchange operations. The power exchange operations may be in the form of power input operations or optionally power output operations. The EV may be operable in a power input mode or a power output mode. When the EV is in the power input mode, the EV is in power input operations and electrical energy will flow from an external energy source into the EV via the power exchange mode. When the EV is the power output mode, the EV is in power output operations and electrical energy will flow from the EV to an external load via the power exchange mode.

[0017] When the EV is in the power input mode, which may be a battery charging mode to replenish stored energy in the REESS, the power exchange port is configured as a battery charging port (“charging port” in short) which is devised to facilitate charging of the on-board battery assembly by an external or off-board electrical power source. When in this operation mode, the charging port is configured as a power interface to facilitate electrical interconnection between the electrical system of the BeV and an external electrical power source. When in the charging mode, power is delivered to the on-board REESS via the power exchange port.

[0018] When the EV is in the power output mode, energy stored on the REESS will be delivered to an external load via the power exchange port, and the power exchange port is to operate as a power output port (“charging port” in short). When in this operation mode, the power output port is configured as a power interface to facilitate electrical interconnection between the electrical system of the BeV and an external load.

[0019] The power exchange port, for example the charging port, is typically mounted on the vehicle body and immediately under a cover which is a port cover that is mounted on the exterior of the vehicle body, and can be opened when there is a need to access the power exchange port. A port cover is usually an integral part of the vehicle outer body, and is configured to facilitate easy access to the charging port.

[0020] The power exchange port, including it shape and layouts, may be configured to comply with prevailing standards on power exchange operations to facilitate power exchange operations. During power exchange operations, the power exchange port will be in power exchange coupling with a compatible power coupling interface which may be referred to as a power coupling head. A power coupling head may be referred to as a charging head or a charging gun.

[0021] During power exchange operations including charging of the battery, a charging head may be mechanical and electrically coupled to the EV via the power exchange port. The charging head, which is also referred to as a charging gun, or gun in short, is typically of an industrial standard type.

[0022] Currently, there are several major standards on charging guns for BeV charging, for example, GB / T 20234 of China, IEC 61851& IEC 62196 of the International Electrotechnical Commission, SAE J1772 of the United States, NACs of Tesla, and CHAdeMo of Japan, and each standard charging gun has a specific shape and pin / hole layout.

[0023] In addition, there are also several major standard communication protocols for BeV charging, for example, OCPP, ISO 15118, IEC 61851 , CHAdeMo, CCS, etc. A charging standard is usually associated with a standard charging protocol to computer-based intelligent charging.

[0024] Each BeV has an on-board computer to facilitate intelligent vehicle control, including operational and charging control. The on-board computer may comprise a plurality of controllers including a main controller and a plurality of peripheral controllers. Each controller is an on-board controller which may be a computer-based controller, a logic-array-based controller, and etc. without loss of generality.

[0025] Since the charging port has to be easily exposable and accessible for convenient battery charging, but is also an integral part of the high voltage circuit system of the BeV, a BeV is typically configured such that the high voltage circuit system and the charging port are electrically isolated, that is electrically insulated from each other, unless the BeV is in battery charging.

[0026] To prepare a BeV for power exchange such as battery charging, an operator is usually required to open the port cover such as the charging port cover, for example, by selecting an option on an on-board control panel or by means of a maintenance controller. After the port cover is put into an opened position, the power exchange port, for example, the charging port is still electrically isolated from the high-voltage electrical system until a pre-checking routine has been satisfactory completed.

[0027] To ensure a BeV is in ready for power exchange such as battery charging, the onboard controller of a BeV will check whether there is due coupling between a charging gun and the BeV, or more specifically between the charging gun and the power exchange port such as the charging port.

[0028] When the BeV power exchange port such as the charging port is in due coupling with a charging gun and is ready to proceed with power exchange such as charging upon completion of successful protocol exchange between a charging station and the BeV or between the BeV and an external load. The BeV will operate internal switches to connect the live parts of the high-voltage system and the power exchange port such as a charging port or the power output port after the aforesaid pre-charge conditions are fulfilled.

[0029] A typical BeV has an onboard control system which is configured to control operations of the entire vehicle, including for example, battery management such as battery charging, power output and operation of the traction motor(s). The onboard control system, which is commonly referred to as an on-board computer or “computer” in short, has to be a smart or intelligent control system because of the highly complicated operational and safety requirements of BeV. Checking of the pre-charge conditions, operation of the isolation switches is typically performed by an on-board computer which is also known as an on-board controller.

[0030] Methods and apparatuses to facilitate safe and non-destructive or non-invasive measurement of insulation parameters of the live parts of the high-voltage electrical system of an EV (also referred to herein as BeV) are disclosed. “Live parts” herein means the conductive part(s) intended to be electrically energized under normal operating conditions, and "high voltage" means the classification of an electric component or circuit, if its working voltage is > 60 V and < 1500 V DC or > 30 V and < 1000 V AC root mean square (rms), as stipulated in the UN Document.

[0031] The vehicle (EV or BeV) comprises a REESS such as a battery assembly for supplying traction power to drive an electrical prime mover of the EV, a power exchange port, a switchable DC bus system which is configured to provide a power exchange path between the battery assembly and the power exchange port when the vehicle is in a power exchange mode, a controller configured for protocolled data communication via the power exchange port, a vehicle chassis which is an electrical chassis; wherein the battery assembly has a high-voltage positive terminal which is connected to a high-voltage positive conductor of the DC bus system and a high-voltage negative terminal which is connected to a high-voltage negative conductor of the DC bus system. The DC bus system is a high-voltage bus system comprising high- voltage live parts (“live parts” in short).

[0032] The method for measuring electrical parameters of an EV for determination of insulation parameters comprises: connecting electronic circuitry to the power exchange port, the electronic circuitry including an isolation resistance measurement circuitry; establishing data communication with the EV so that the EV is switched into a power exchange mode and so that the isolation resistance measurement circuitry is connected between the live parts and the electrical chassis of an EV; taking and / or recording voltages measurements between the live parts and the electrical chassis of an EV while the EV is operating in the power exchange mode; and processing the voltage measurements to obtain isolation parameters for determining electrical insulation of the EV.

[0033] The method may include: detaching the isolation resistance measurement circuitry from the EV after taking and / or recording the voltages measurements.

[0034] The power exchange mode may be a power input mode or a power output mode.

[0035] The power input mode is also referred to as battery charging mode.

[0036] The power exchange port may be a battery charging port when the EV is operating in the battery charging mode and the power exchange port may be a power output port when the EV is operating in the power output mode. The power output port and the power input port may be a single physical port or separate physical ports.

[0037] The live parts of the EV comprise a DC high-voltage bus system (“DC bus system” in short) having a DC high-voltage positive side (“positive side” in short) and a DC high-voltage negative side (“negative side” in short).

[0038] The positive side includes a DC high-voltage positive conductor (or “positive conductor” in short) and positive terminal of the battery assembly.

[0039] The negative side includes a DC high-voltage negative conductor (or “negative conductor” in short) and negative terminal of the battery assembly.

[0040] The power exchange port and the DC high-voltage bus system may be isolated, i.e., electrically isolated, when not in the power exchange mode, and connected, i.e., electrically connected, when in the power exchange mode.

[0041] When the power exchange port and the DC high-voltage bus system are connected, the power exchange port and the DC high-voltage bus system are interconnected by a low-impedance bus system comprising a low-impedance positive path and a low-impedance positive path.

[0042] The isolation resistance measurement circuitry may be included in an insulation monitoring device (IMD), for example, the GYID-10 series DC IMD the specifications of which are incorporated herein by reference.

[0043] The live parts of the EV may comprise an AC high-voltage bus system which interconnects the power exchange port and an AC / DC converter, and the AC / DC converter is configured as an interface between the AC high-voltage bus system (“AC bus system” in short) and the DC high-voltage bus system.

[0044] The AC bus system has a live side and a neutral side. The live side may comprise one or three live conductors and the neutral side comprises a neutral conductor.

[0045] The AC bus system and the DC bus system are galvanically isolated by the AC / DC converter.

[0046] The isolation resistance of the AC bus system may be measured by an IMD, for example, the GYID-10 series AC IMD.

[0047] The method, in another perspective, may be described as comprising: establishing data communication with the EV so that the vehicle is switched into a power exchange mode, the power exchange mode being a battery charging mode or a power export mode; measuring battery terminal voltages of the EV with respect to the electrical chassis of the EV via the power exchange port; and processing the battery terminal voltages, which are voltages measured with respect to the electrical chassis of the EV to determine isolation resistance and / or insulation status of the EV.

[0048] An apparatus suitable for practicing the method may comprise electronic circuitry for connecting to the power exchange port of an EV.

[0049] The electronic circuitry may comprise controller circuitry and measurement circuitry.

[0050] The measurement circuitry may comprise isolation resistance measurement circuitry including voltage sensors. The controller circuitry may be configured to perform protocolled data communication with the EV so that the EV is switched into a power exchange mode and so that the isolation resistance measurement circuitry is connected between the live parts and the electrical chassis of an EV; to take and / or record voltages measurements between the live parts and the electrical chassis of an EV while the EV is operating in the power exchangemode; and to process the voltage measurements to determine isolation resistance and / or electrical insulation status of the EV.

[0051] The isolation resistance measurement circuitry may comprise a resistor or a plurality of resistors if known values for switchable connection between live parts and the electrical chassis of the EV.

[0052] The apparatus may comprise power circuitry to facilitate power exchange between the EV and the apparatus via the power exchange port.

[0053] The apparatus may comprise a power coupling port to couple with the power exchange port of the EV.

[0054] The power coupling port may be configured as a charging port or a charging gun.

[0055] In this specification, “power exchange” and “power communication” are interchangeably used, and the terms insulation, energy and power mean electrical insulation, electrical energy and electrical power respectively, unless the context requires otherwise.Figures

[0056] The present disclosure is described with reference to the accompanying figures, in which:

[0057] Figure 1 is a block diagram of an example apparatus according to the present disclosure,

[0058] Figure 2 is a schematic diagram depicting the example apparatus in operation,

[0059] Figures 3A to 3C are flow diagrams of example process flows of the present disclosure.

[0060] Figures 3D to 3E are respectively flow diagrams of AC and DC arc fault monitoring of the present disclosure.Description

[0061] The methods of the present disclosure may be practiced with the aid of an apparatus. An example apparatus suitable for practicing the method of present disclosure may comprise:- data communication circuitry or data exchange configured for entering into data communication with an electrical vehicle (“EV”) and switching the EV into a power communication mode by data exchange with the EV, and- electronic circuitry for obtaining and optionally processing material electrical parameters of the EV for isolation parameter determination while the EV is in power communication operations.

[0062] When the EV is switched into the power communication mode, also referred to power exchange mode, the EV will be ready for power communication between the on-board electrical energy storage device of an EV and an external power circuitry.

[0063] An external power circuitry is used as a tool to facilitate obtaining, acquisition or procurement of material electrical parameters of the EV for isolation parameter determination because the internal power circuitry of an EV is heavily sealed, guarded and / or isolated, and accessing

[0064] The on-board electrical energy storage device of an EV, also known as rechargeable electrical energy storage system (“REESS”), is for providing electrical energy for powering the traction system of the EV.

[0065] When the EV is in power communication operations, electrical power will flow between the on-board electrical energy storage device of the EV and a power circuitry via a power exchange port of the EV.

[0066] The power exchange port may be one which is commonly referred to as a charging port, but the function of what is known as a charging port is no longer limited to EV charging, but has extended to include power output to an external load, for example, in processes what are known as “V2V” (vehicle-to-vehicle) or “V2X” (vehicle-to-anything) operations.

[0067] The power communication may be in a first mode or a second mode.

[0068] When in the first mode, electrical energy from an external source is supplied to the REESS of the EV, and the stored electrical energy of the REESS will increase as a result. When in this power communication mode, the REESS of the EV is being charged and the EV is in a “charging” mode or “battery charging” mode.

[0069] When in the second mode, electrical energy is supplied by the REESS to an external load, and the stored electrical energy of the REESS will decrease as a result. When in this power communication mode, the REESS of the EV is being discharged and the EV is in a “power output” mode or “power export” mode.

[0070] Currently, REESS of EVs are mostly in the form of battery assemblies in the multi-kilo- watt capacity. In this specification, the terms “battery assembly” and “REESS” are used interchangeably and have same meaning unless the context otherwise requires.

[0071] Therefore, the power communication between an EV and the external power circuitry may be i) by way of direct power communication between the on-board electrical energy storage device of an EV and the external power circuitry, or ii) by way of power communication between the on-board electrical energy storage device and the apparatus via an on-board power converter of the EV.

[0072] When the EV and an external power circuitry are in direct power communication, the REESS and the charging port of the EV are interconnected by a low-impedance power path of negligible or insignificant resistance.

[0073] When the EV and an external power circuitry are in power communication via an onboard power converter, the power communication is referred to as indirect power communication herein, and the onboard power converter is connected to the power exchange port and the REESS by means of a pair of low-impedance power paths, including a low- impedance power path of negligible or insignificant resistance interconnecting the power exchange port and the onboard power converter and another low-impedance power path of negligible or insignificant resistance interconnecting the onboard power converter and the REESS.

[0074] The apparatus may comprise an on-apparatus power circuitry to facilitate the power communication and parameter acquisition. This on-apparatus power circuitry, while external to the EV, is internal to the apparatus. In this specification, the term power circuitry means a power circuitry which is external to the EV, unless the context requires otherwise.

[0075] The power circuitry may comprise a first power port, a second power port and at least one power path interconnecting the first power port and the second power port. The power path may be a DC power path comprising a positive high-voltage DC conductor and a negative high-voltage DC conductor. The power path may be an AC power path comprising a set of live conductors and a neutral conductor. The set of live conductors consists of three live conductors for a three-phase AC system and a single live conductor for a single-phase AC system based on current standards.

[0076] The power circuitry may comprise a plurality of power paths interconnecting the power input port and the power output port.

[0077] The power paths of the plurality of power paths are alternative power paths, and each one of the power paths is selectively operable and only one of the power paths is selected as an operating power path at one time.

[0078] The plurality of power paths may include a first power path and a second power path which is an alternative path to the first power path.

[0079] The first path may be a DC power path which is configured for DC power output at the power output port and the second path may be an AC power path which is configured for AC power output at the power output port.

[0080] The power circuitry may be configured so that the power path or the plurality of power path are located with a sealed and insulated housing so that only the input port and the output port are user accessible for safety operations.

[0081] The apparatus may be configured so that the first power port is a power input port and the second power port is a power output port configured for power and data coupling to the EV. When the apparatus in this first configuration, which is an EV charger configuration, the EV, or more specifically the REESS of the EV, is in a power input mode, also known as power import mode, charging mode, or battery charging mode.

[0082] The apparatus may be configured so that the first power port is a power output port for power output to an external load, and the second power port is a power input port for power and data coupling to the EV. When in this second configuration, the EV, or more specifically the REESS of the EV, will be in a power output mode, also known as power export mode.EV-charger configuration

[0083] When the apparatus in the EV charger configuration, or charger configuration in short, the power input port is configured as a power-input interface for coupling to a power source, which is the source of the electrical power to be supplied to the EV by the apparatus; and the power output port is configured as a power-output interface for coupling with the EV, so that electrical power can flow from the apparatus to the EV.

[0084] The power circuitry may comprise a charging head or a plurality of charging heads which is connected to the power output port. The charging head or each charging head of the plurality of charging heads may be configured as a charging gun having a specific shape and layout specifications conforming to a specific type of EV or EV charging standards.

[0085] The charging gun is configured for establishing protocolled data communication and power communication with an EV. Protocolled data communication means that data communication is performed according to prevailing standards for data communication with the EV. The EV will enter into a charging mode upon successful completion of the protocoled data communication and charging connection will be established between the apparatus and the EV, with the charging gun and the charging portion operating as power communication interfaces or charging interfaces.

[0086] The power source may be an AC (alternating current) power source such as the mains power supply or a DC (direct current) power source.

[0087] The power source may be an internal power source of the apparatus or an external power source with respect to the apparatus.

[0088] The DC power path may comprise a power converter.

[0089] The power converter may an AC / DC power converter so that DC output power can be supplied by the apparatus when the power source is an AC power source.

[0090] The AC / DC power converter may be a universal AC / DC power converter having a variable DC output voltage and the DC output voltage can be selected by electronic control.

[0091] The AC / DC power converter may be configured for 3-phase or single-phase power input.

[0092] The power converter may be a DC / DC power converter so that DC power having same or different output voltage to the DC input voltage of the power source can be supplied by the apparatus when the power source is a DC power source.

[0093] The power converter may be a power converter assembly including both an AC / DC power converter and a DC / DC power converter, and each one of the power converters may have a variable voltage output that can be selected by electronic control operations.

[0094] The power converter, whether AC / DC and / or DC / DC, has an input side and an output side, and the input side and the output side are preferably galvanic isolated.

[0095] The power circuitry may be switchable so that a power path can be selected from the plurality of power paths by electronic control operations.

[0096] The electronic circuitry may comprise sensing circuitry, control circuitry, data communication infrastructure, and optionally monitoring circuitry, peripheral circuitry, and / or other circuitries.

[0097] The sensing circuitry may comprise sensing components or sensing sub-assemblies for sensing, measuring and / or obtaining electrical parameters for determining material electrical isolation parameters of the EV.

[0098] The control circuitry is configured for controlling the overall operation of the apparatus, including sending electronic control signals to operate switches whereby a power path is selected as an operational power path, performing data communication with an EV, acquisition of data from the power paths, performing other control functions, and etc.

[0099] When the apparatus and an EV are in charging connection, electrical power for charging the battery assembly of EV will flow from the power source to the EV via the apparatus.

[0100] The power output port interface is also configured as a data communication interface so that data can be exchanged between the apparatus and the EV by way of protocoled data communication to establish charging connection between the apparatus and the EV.

[0101] The power output port interface may comprise a charging gun which is configured to establish charging connection between the apparatus and the EV.

[0102] The apparatus may comprise a plurality of charging guns connected to the power output port interface for selection.

[0103] The plurality of charging guns may comprise different types of charging guns conforming to different EV requirements or different EV standards for selection.

[0104] The plurality of charging guns may have different pin, socket and / or shape configurations to be compatible with different charging port configurations of different EV.

[0105] The control circuitry may comprise a controller, data storage devices including volatile and non-volatile memory devices, switches which may comprise electronic switches, electromechanical switches, mechanical switches, arc-fault circuit breakers, etc., plus data and control buses.

[0106] The control circuitry may be configured to select one of the switchable power paths as a charging path for supplying charging power to an EV in charging connection.

[0107] The control circuitry may be configured to enter into protocoled data communication with an EV via the power output port interface or the charging gun to establish charging connection therewith.

[0108] The data storage device may be prestored with executable instructions so that the controller can upon execution of the stored instructions enter into protocoled data communication with the EV.

[0109] An EV may be configured to have an AC charging mode or a DC charging mode.

[0110] When the EV is in the DC charging mode, a low impedance current path will be established between the battery assembly terminals and the power output port interface to facilitate battery charging.

[0111] When the EV is in the AC charging mode, a low impedance current path will be established between an on-board AC-DC converter and the power output port interface to facilitate battery charging, and the battery assembly terminals of the EV are shunned behind the on-board power converter.

[0112] The power path selection may be performed by the controller operating the switches upon execution of the stored instructions.

[0113] The controller may comprise a microprocessor or a cluster of microprocessors.

[0114] The monitoring circuitry may comprise a plurality of sensors such as voltage sensors, current sensors, insulation monitoring devices (“IMD”), arc-fault detectors, etc.

[0115] The sensors may be disposed for obtaining voltage and current parameters on each conductor or some of the conductors of the power circuitry.

[0116] For example, voltage and current sensors may be disposed to detect voltage and current of the positive DC conductor and the negative DC conductor, each of which is a high- voltage DC conductor.

[0117] For example, voltage and current sensors may be disposed to detect voltage and current of each of the AC live conductors and AC neutral conductor.

[0118] The data storage devices may comprise RAM, ROM, SSD, etc.

[0119] The data storage device may be prestored with a plurality of data communication protocols to facilitate protocolled data communication between the apparatus and different types, models and / or brands of EV.

[0120] The apparatus may be configured so that a user may input the brand, type, and / or model and the controller will select a set of data communication protocols for protocolled data communication to established charging connection between the apparatus and the EV.

[0121] The control circuitry and the monitoring circuitry are parts of electronic circuitry of the apparatus and the electronic circuitry of the apparatus may comprise additional peripheral circuitry such as telecommunication circuitry, for example, wireless telecommunication frontends for WiFi, Bluetooth, ethernet, and like applications.

[0122] The apparatus may comprise a user interface to facilitate human-machine interaction (HMI). EV information such as its brand, type and / or model may be input to the apparatus by means of the HMI.

[0123] The power input port, the power output port and the switchable power paths are parts of the power circuitry of the apparatus.

[0124] The HMI may for example include a display, for example, a touch display panel for data input and information display.

[0125] The apparatus may comprise connection ports to facilitate connection with an external user interface and / or with external computers.

[0126] The apparatus may comprise a chassis connector for establishing electrical connection with the chassis of an EV, whereby a common reference ground between the apparatus and the EV is established.

[0127] The apparatus may comprise a housing, which may be a metallic housing, to make it a stand-alone apparatus or as a module of a modular system.

[0128] The apparatus may have a first reference ground and a second reference ground which are electrically isolated from each other, each ground being an electrical ground.

[0129] The first reference ground may be tied to the AC power supply ground and the second reference ground may be a circuit ground of the electronic circuitry which is for connection to the electrical ground of the EV, as represented by the vehicle chassis.

[0130] The metallic housing of the apparatus may be selected as the first reference ground which is tied to the earth or ground terminal of the external power supply for operational safety.

[0131] As the first and second reference ground are electrically isolated, there is no common electrical ground between the power input port and the electronic circuitry.

[0132] The apparatus may have an overall form factor of a tower so that its height is larger than its base width or base length.

[0133] The apparatus has a circuit ground which is a floating ground (FG) that is electrically isolated from the apparatus ground or the ground of the external power supply.

[0134] The chassis connector is connected to and forms part of the floating ground and the EV chassis is electrically isolated with the ground of the external power supply when the common ground is established between the EV and the floating ground of the apparatus.

[0135] The apparatus may be configured as a mobile apparatus, with wheels supporting the apparatus base.Example apparatus

[0136] Referring to Figure 1 , an example apparatus 10 according to the present disclosure comprises power circuitry and electronic circuitry for controlling operations of the apparatus.

[0137] The power circuitry comprises a power input port, a power output port, and a plurality of power paths interconnecting the power input port and the power output port.

[0138] The power paths of the plurality of power paths are selectable power paths so that only one of power paths is activated, that is, in operational, at a time.

[0139] The plurality of power paths comprises a DC power path and an AC power path which are parallel but alternative paths.

[0140] The DC power path is configured for DC power output and comprises a power converter interconnecting the power input port and the power output port.

[0141] The power converter has a power input side and a power output side which is galvanically isolated from the power input side.

[0142] The example power converter is an AC / DC converter 12 having an AC input side and a DC output side.

[0143] The AC / DC converter 12 is a universal converter having a variable DC output voltage in the range of between 300V and 850V and a variable DC current of up to 30A. Such an output range would cover most EV in market.

[0144] The AC power path is configured for AC power output and is a low-impedance power path interconnecting the power input side and the power output side when in operation.

[0145] The power circuitry comprises a power input portion, or an input portion in short, which is connected to the power input port for receiving power from an external power source.

[0146] The power input portion interconnects the power input port and the input side of the power converter with an AC power bus system.

[0147] The input portion is a four-wire conductor section configured for three-phase AC power input. The four-wire conductor section comprises three live conductors and one neutral conductor.

[0148] The input portion comprises an AC arc-fault detector in the form of an arc-fault MCB 14A, a pre-MCB bus section, and a post-MCB bus section, with the arc-fault MCB 14A interconnecting the pre-MCB bus section and the post-MCB bus section, each of which is a four-wire conductor section.

[0149] The arc-fault MCB 14A may comprises a plurality of AC arc-fault circuit breakers which is to operate to isolate the post-MCB bus section from the pre-MCB bus section when arc fault occurs or is detected in the input portion.

[0150] The DC power path includes a DC power output portion (or DC output portion) interconnecting the output side of the power converter and the power output port. The DC output portion is a DC bus portion 30 comprising a positive (+ve) conductor which is a HVDC power conductor and a negative (-ve) conductor which is another HVDC power conductor.

[0151] The AC power path includes an AC bus portion 20 which interconnects the output side of the arc-fault MCB 14A and the power output port. The AC bus portion is a four-wire conductor section comprising three live conductors and one neutral conductor.

[0152] The power input portion, the power converter, and the DC bus portion 30 cooperate to form a first charging path which is a DC charging path, also known as a DC power path.

[0153] The pre-MCB section, the arc-fault MCB 14A and the AC bus portion 20 cooperate to form a second charging path which is an AC charging path, also known as an AC power path.

[0154] The AC bus portion 20 is a switchable bus portion comprising a first AC bus section and a second AC bus section which are interconnected by a switch assembly SW1 16A. The switch assembly SW1 16A is operable in a first state which is a first switching state or a second state which is a second switching state.

[0155] When the switch assembly SW1 16A is in the first switching state or the “ON” state, the switch assembly SW1 16A interconnects the first AC bus section and the second AC bus section, thereby forming a low-impedance AC bus portion to facilitate AC charging power flow along the AC power path.

[0156] When the switch assembly SW1 16A is in the second switching state or the “OFF” state, the first AC bus section and the second AC bus section are isolated by the switch assembly SW1 16A, thereby forming a high-impedance AC bus portion, and thereby isolating the power input port or power input portion from the power output portion.

[0157] The first AC bus section and the second AC bus section are power bus portions having identical electrical characteristics including voltage rating, current rating, insulation rating, etc.

[0158] The DC bus portion 30 is a switchable bus portion comprising a first DC bus section and a second DC bus section which are interconnected by a switch assembly SW2 16B. The switch assembly SW2 16B is operable in a first state which is a first switching state, or a second state which is a second switching state.

[0159] When the switch assembly SW2 16B is in the first switching state or the “ON” state, the switch assembly SW2 16B interconnects the first DC bus section and the second DC bus section, thereby forming a low-impedance DC bus portion to facilitate DC charging power flow along the DC power path.

[0160] When the switch assembly SW2 16B is in the second switching state or the “OFF” state, the first DC bus section and the second DC bus section are isolated by the switch assembly SW2 16B, thereby forming a high-impedance DC bus portion, and thereby isolating the power converter from the power output portion.

[0161] The first DC bus section and the second DC bus section are power bus portions having identical electrical characteristics including voltage rating, current rating, insulation rating, etc.

[0162] The AC charging path and the DC charging path share a common input portion which includes the MCB and the pre-MCB section.

[0163] The insulation parameters and conditions of an EV can be determined using the apparatus, and more particularly, with the apparatus and the EV in charging connection.

[0164] For battery EV, the insulation parameters of importance are those of the HVDC portion, which comprises HVDC buses and the battery terminals, which are HVDC terminals. The HVDC buses and the HVDC terminals are normally well sealed and isolated to meet stringent safety requirements.

[0165] In order to determine the relevant or material electrical parameters, electrical sensors 18 such as voltage and current sensors are disposed, for example, for voltage sensing, current sensing, or insulation measurements.

[0166] The sensors may be disposed at selection portions or sections of the power circuitry for acquisition of electrical parameters and monitoring operational conditions.

[0167] For the DC output portion, voltage and current sensors may be disposed to sense the voltages and currents of each of the individual DC conductors, that is, the positive and negative HVDC conductors.

[0168] For the input portion, voltage and current sensors may be disposed to sense the voltages and currents of each of the AC conductors, that is the live conductors and the neutral conductors in the post switch portion, and / or on the input side of the power converter.

[0169] For the AC portion, voltage and current sensors may be disposed to sense the voltages and currents of each of the AC conductors, that is the live conductors and the neutral conductors.

[0170] Instead of or in addition to using discrete voltage and current sensors, devices known as IMD may be used for insulation parameter determination.

[0171] IMD (insulation monitoring device) can be disposed to monitor insulation parameters of the DC output portion and the AC bus portion.

[0172] Insulation monitoring devices suitable for EV applications are available from, for example, Blue Jay® (GYID IMD), Bender Inc., etc.

[0173] Voltage sensors may be disposed to monitor voltages on the input side of the power converter.

[0174] The sensors and / or the IMD may be disposed, for example, to monitor the voltages and / or currents of HVDC positive conductor and the HVDC negative conductor with respect to the circuit ground (FG) to determine the material electrical parameters. A DC IMD may be used for this purpose.

[0175] The sensors and / or the IMD may be disposed, for example, to monitor the voltages and / or currents of the AC conductors in the AC bus portion individually with respect to thecircuit ground (FG) to determine the electrical material parameters. An AC IM D may be used for this purpose.

[0176] The electronic circuitry comprises a controller for controlling operation of the apparatus, including protocolled data communication with the EV, controlling switching operations of the various switches, acquisition of electrical parameters from the various sensors, and processing the electrical parameters to determine insulation parameters and / or insulation status.

[0177] The electronic circuitry comprises an infrastructure of data and control buses to facilitate control operations and data communication.

[0178] The apparatus comprises an arc-fault detector on the output side of the power converter so that the controller is informed of arc-fault.

[0179] In operation, the apparatus is electrically coupled with an EV, for example, with the charging gun and the charging port in electrical and data communication, as shown in Figure 2.

[0180] Referring to Figure 3A, after the charging gun and the charging port are in electrical and data communication in 102, the apparatus and the EV will start protocolled communication for switching the EV into charging mode, as indicated in 104. After successful completion of step 104, the EV will be in a charging mode, as indicated in 106.

[0181] Referring to Figure 3B, the EV is in DC charging mode as a result of the protocolled communication of 104, and the apparatus will start to perform DC charging on the EV and will be in DC charging conditions, as indicated in 114. The apparatus will then operate the sensors and / or the DC IMD to acquire electrical parameters to determine insulation characteristics, as indicated in 116.

[0182] Referring to Figure 3C, the EV is in AC charging mode as a result of the protocolled communication of 104, and the apparatus will start to perform AC charging on the EV and will be in AC charging conditions, as indicated in 124. The apparatus will then operate the sensors and / or the AC IMD to acquire electrical parameters to determine insulation characteristics, as indicated in 126.

[0183] The voltage measurements may include measuring and / or recording: voltage (Vi) between the negative side and the electrical chassis, voltage (V2) between the negative side and the electrical chassis, and voltage (Vb) of the battery assembly.

[0184] If Vi is larger than V2, the method comprises inserting a resistance (Ro) of known resistance value between the negative side and the electrical chassis, and measure thevoltage (V ) between the negative side and the electrical chassis. The processing includes calculating the isolation resistance according to the formula: Rt= Rox Vbx (1 / V ~ W

[0185] If V2is larger than Vi, the method comprises inserting a resistance (Ro) of known resistance value and the electrical chassis, and measure the voltage (Vi’) between the negative side and the electrical chassis. The processing includes calculating the isolation resistance according to the formula: Rt= Rox Vbx (1 / V2' - 1 / V2).

[0186] The resistance (Ro) may be a part which is built-into the isolation resistance measurement circuitry and may be switchable to connect between the positive side and the electrical chassis or between the negative side and the electrical chassis.

[0187] When the measurement is performed in the battery charging mode, charging power is supplied to the battery assembly from an external power source via the battery charging port.

[0188] When the measurement is performed in the power output mode, power is output from the battery assembly to an external load via the power output port.

[0189] The electronic circuitry is configured to monitor arc faults, as shown in Figures 3D and 3E. When the EV is in AC charging mode 132 and in AC charging conditions 134, the control circuitry is configured to monitor possible arc faults by means of the AC arc fault detector. When arc fault is detected, the arc fault MCB 14A will break the AC circuit and an alert signal is sent to the control circuitry. When the EV is in DC charging mode 142 and in DC charging conditions 144, the control circuitry is configured to monitor possible arc faults by means of the DC arc fault detector 14B. When arc fault is detected, the arc fault detector 14B will send an alert signal to the control circuitry and the control circuitry will turn off the switch assembly SW2 16B.

[0190] While the present disclosure is described with reference to example embodiments, the example embodiments are provided to facilitate better understanding of the disclosure and should not be interpreted in a limiting manner.

Claims

Claims1) A method for measuring electrical parameters of an EV for determination of insulation parameters, wherein the vehicle comprises a battery assembly for supplying traction power to drive an electrical prime mover of the EV, a power exchange port, a switchable DC bus system which is configured to provide a power exchange path between the battery assembly and the power exchange port when the vehicle is in a power exchange mode, a controller configured for protocolled data communication via the power exchange port, a vehicle chassis which is an electrical chassis; wherein the battery assembly has a high-voltage positive terminal which is connected to a high-voltage positive conductor of the DC bus system to form a positive side of the DC bus system and a high-voltage negative terminal which is connected to a high-voltage negative conductor of the DC bus system to form a negative side of the DC bus system; and wherein the method comprises: connecting electronic circuitry to the power exchange port, the electronic circuitry including an isolation resistance measurement circuitry; establishing data communication with the EV so that the EV is switched into a power exchange mode and so that the isolation resistance measurement circuitry is connected between live parts and the electrical chassis of an EV; taking and / or recording voltage measurements between the live parts and the electrical chassis of an EV while the EV is operating in the power exchange mode; and processing the voltage measurements to obtain isolation parameters for determining electrical insulation of the EV.2) The method of claim 1 , wherein the high-voltage positive terminal and the high-voltage negative terminal are battery assembly terminals both of which are in electrical communication with the power exchange port when the EV is in the power exchange mode, and one or both of which is isolated from the power exchange port when the EV is not in the power exchange mode; wherein the method comprises: switching the EV into a power exchange mode so that both the high-voltage positive terminal or the positive side of the DC system and the high-voltage negative terminal or the negative side of the DC system are in electrical communication with corresponding terminals of the power exchange port;measuring voltages at the corresponding terminals with respect to the electrical chassis of the EV via the power exchange port to obtain positive side voltage and negative side voltage; and processing the positive side voltages and the negative side voltages to obtain isolation resistance.3) The method of claim 1 , wherein the method comprises: switching the EV into DC charging mode which is a battery charging mode; supplying DC charging power to the EV while the EV is in a battery charging connection and a battery charging state, wherein the DC charging power is to flow from a battery charging port, which is the power exchange port, into the battery assembly, the DC charging power comprising a positive charging voltage and a negative charging voltage with respect to the electrical chassis of the EV; and measuring the positive charging voltage and the negative charging voltage to determine isolation resistance and / or insulation status of the EV.4) The method of claim 1 , wherein the method comprises: switching the EV into AC charging mode which is a battery charging mode; supplying AC charging power to the EV while the EV is in a battery charging connection and a battery charging state, wherein the AC charging power is to flow from a battery charging port, which is the power exchange port, into the battery assembly via a power converter, the AC charging power comprising at least one live conductor voltage and a neutral conductor voltage with respect to the electrical chassis of the EV; and measuring the live conductor voltage and the neutral conductor voltage to determine isolation resistance and / or insulation status of the EV.5) The method of claim 4, wherein the AC charging power comprising a plurality of live conductor voltages and a neutral conductor voltage with respect to the electrical chassis of the EV; and wherein the method comprises: measuring the live conductor voltages and the neutral conductor voltage individually with respect to the electrical chassis of the EV to determine isolation resistance and / or insulation status of the EV.6) The method according to any preceding claims, wherein the method comprises measuring voltages for determining isolation resistance and / or insulation status of theEV using an apparatus in electrical communication with the power exchange port, the apparatus not being an integral part or a built-in part of the EV.7) The method of claim 6, wherein the method comprises coupling the apparatus with the EV so that the apparatus and the EV are in data and electrical communication.8) The method of claim 7, wherein the apparatus has electronic circuitry, power circuitry and a circuitry ground, and wherein the method comprises electrically connecting the circuitry ground of the apparatus with the electrical chassis of the EV to establish a common ground between the apparatus with the electrical chassis of the EV; wherein the apparatus has a power input portion for connection to a power source having an earthing connection, and wherein the common ground is isolated from the earthing connection; and / or wherein the apparatus has a metallic housing which is configured for tying to the earthing connection, and wherein the common ground is isolated from the metal housing.9) The method of claim 1 , wherein the isolation resistance measurement circuitry comprises a reference resistor (Ro), a plurality of reference resistors of known values, a IMD, or a plurality of IMD for switchable connection between live parts and the electrical chassis of the EV, and wherein the method comprises taking the voltage measurements using the IMD or the plurality of IMD, or taking the voltage measurements before and after the reference resistor (Ro) or the plurality of reference resistors is connected.10) An apparatus for practising the method of any preceding claims, wherein the apparatus comprises electronic circuitry including controller circuitry and measurement circuitry, wherein the measurement circuitry comprises isolation resistance measurement circuitry including voltage sensors; and wherein the controller circuitry is configured: to perform protocolled data communication with the EV so that the EV is switched into a power exchange mode and so that the isolation resistance measurement circuitry is connected between the live parts and the electrical chassis of an EV; to take and / or record voltages measurements between the live parts and the electrical chassis of an EV while the EV is operating in the power exchange mode; and to process the voltage measurements to determine isolation resistance and / or electrical insulation status of the EV.11) The apparatus of claim 10, wherein the apparatus is configured such that the electronic circuitry is to perform protocolled data communication with an EV via a power exchange port of the EV, and wherein the apparatus comprises a power exchange head which is configured to facilitate physical and electrical communication with the EV via the power exchange port of the EV.12) The apparatus of claim 11 , wherein the power exchange head of the apparatus has a shape and layout that are complementary to the power exchange port of the EV, and wherein the power exchange head of the apparatus is configured to be physically detached from the EV while not practising the method.13) The apparatus of claim 10, wherein the apparatus comprises power circuitry which is configured to enter into power communication with the live parts of the EV by means of power coupling between the power exchange head and the power exchange port.14) The apparatus of claim 13, wherein the power circuitry comprises a DC power path having a high-voltage positive conductor and a high-voltage negative conductor in electrical communication with the battery assembly, wherein the DC power path is configured for connection with the live parts of the DC bus system of the EV; and wherein voltage sensors are disposed to obtain positive voltage of the high-voltage positive conductor relative to the electrical chassis of the EV and negative voltage of the high- voltage positive conductor relative to the electrical chassis of the EV.15) The apparatus of claim 14, wherein the voltage sensors comprise a reference resistor (Ro) or a plurality of reference resistors of known values which is for switchable connection between live parts and the electrical chassis of the EV, or wherein the voltage sensors comprise a IMD or a plurality of IMD.16) The apparatus of claim 13, wherein the power circuitry comprises a DC power path having a high-voltage positive conductor and a high-voltage negative conductor in electrical communication with the battery assembly, and wherein an IMD which is an insulation monitoring device is disposed to obtain positive voltage of the high-voltage positive conductor relative to the electrical chassis of the EV and negative voltage of the high-voltage positive conductor relative to the electrical chassis of the EV.17) The apparatus of claim 13, wherein the power circuitry comprises a power input port, a power output port, and an AC / DC power converter interconnecting the power input port and the power output port to form a DC power path; and wherein the AC / DC power converter has a power input side which is connected to the power input port and a power output side which is connected to the power output portion, the power input side and the power output side being galvanically isolated.18) The apparatus of claim 13, wherein the power circuitry comprises a power input port, a power output port, and at least one power path interconnecting the power input port and the power output port; wherein the power input port is configured for connecting to a power source having a power earth, and the electronic circuitry has a circuit ground which is isolated from the power earth; and wherein the apparatus comprises a connection port for establishing a common electrical ground between the circuit ground and the electrical chassis of the EV.19) The apparatus of claim 13, wherein the power circuitry comprises an AC power path having at least a live conductor and a neutral conductor, and wherein voltage sensors or IMD are disposed to obtain voltage of the live conductor relative to the electrical chassis of the EV and voltage of the neutral conductor relative to the electrical chassis of the EV.20) The apparatus according to any preceding claim, wherein the apparatus is configured as a charger for charging the battery assembly of an EV, and the electronic circuitry comprises a controller which is configured to enter into protocolled data communication with the EV whereby the EV is switched in a battery charging mode, and to collect electrical parameters for determination of isolation parameters of the EV via the charging port of the EV.

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