Patent Description:
The use of arc fault detection modules is important in vehicle applications as there are a number of scenarios where high current flows are necessary within conventional, hybrid and electric vehicles such as automobiles. The most obvious example in a vehicle application would be a case where an electric vehicle's motor is starting. When an electric motor starts, it requires a high current flow, and in some configurations, an arc will occur.

This could potentially cause a traditional automotive fuse or circuit breaker to trip, even though the high current flow associated with motor startup is expected. Existing arc fault detection strategies for vehicles can require expensive components that are typically centralized.

Arc fault detection and protection systems for vehicles are known from <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>, all of whom teaching local arc fault detectors/circuit breakers communicating with a central processing unit, but none involving the central processing unit in the decision to open a circuit breaker or not in response to being notified by the local arc fault detectors that an arcing event has been identified.

The present invention is a vehicle electric system as it is defined in claim <NUM>. The disclosed vehicle electric system which comprises a plurality of arc fault detection modules overcomes the above limitations of fuses, circuit breakers, and existing arc fault detection systems by supervising the circuit and continuously checking to determine if the circuit is experiencing a normal arc condition, or an arc fault condition which must be addressed. The arc fault detection modules can either work independently or with other vehicle systems (such as the power distribution unit and electronic control unit) via the vehicle's internal network (Controller Area Network, or CAN bus) to perform four basic functions - sense, signal condition, process the conditioned signal, and act when an arc fault is detected.

A smaller arc fault detection module can be distributed around the vehicle and connected to individual loads or small clusters of loads. Then, the smaller arc fault detection module can be less expensive than a centralized component. Additionally, the smaller arc fault detection module can be more closely tailored for the load, as by being designed for either a high or low voltage load, or a DC or AC current configuration. With smaller arc fault detection modules, unaffected vehicle systems can function normally if a discrete arc occurs, and the arc fault detector is more able to react in its intended environment for high or low voltages and DC or AC faults. Below are additional alternatives for actuating a contactor to interrupt a load or cluster of loads.

The plurality of modules each comprise an arc fault detection unit comprising one or more sensors configured for monitoring an alternating current circuit or a direct current circuit for signs of an arc fault and configured for outputting arc fault data; signal conditioning circuitry for receiving and translating arc fault data for processing; a processing unit connected directly or indirectly to the signal conditioning circuitry, the processing unit configured to receive arc fault data from the signal conditioning circuitry and configured to identify an arc fault condition; and a notification device connected to the processing unit, the notification device configured to notify a supervisory controller of an arc fault and configured to communicate other data to the supervisory controller.

The processing unit can be connected directly to the signal conditioning circuitry in the arc fault detection module.

A notification device can be directly connected to the arc fault detection module.

The processing unit can be remote from the arc fault detection unit and communicate via the vehicle's Controller Area Network, or CAN bus.

The notification device may be replaced by a contactor directly or indirectly connected to the processing unit, with the contactor configured to interrupt a flow of current when the arc fault condition is identified.

The processing unit can be a microcontroller, where the microcontroller is configured to command the notification device to indicate when a fault has occurred; and where the microcontroller is configured to issue commands to a contactor to interrupt a flow of alternating current circuit or direct current through the circuit monitored by the arc fault detection module.

Alternatively, the processing unit can be a centralized electronic control unit, where the centralized electronic control unit is configured to receive and process signal data from other arc fault detection modules and controllers connected to the power distribution system of the vehicle. The centralized electronic control unit is configured to receive and process the arc fault data and to determine when an arc fault condition has occurred, and transmit a command to the contactor to interrupt a flow of alternating current circuit or direct current through the circuit monitored by the arc fault detection unit.

These modules can be configured for installation on either a direct current or alternating current circuit, including direct or indirect connections to a powered unit, such as an on-board charger, an inverter, or a DC-DC converter.

Variants of the arc fault detection module can be configured so they may act independently of other aspects of the vehicle's electrical system. These modules are configured to observe an alternating current circuit or a direct current circuit for signs of an arc fault and include the signal conditioning circuitry, processing logic and a contactor capable of disabling current flow to the observed circuit. When the processing logic determines an arc fault has occurred, it can take independent action to disable current flow through the circuit. The module will then maintain the circuit in a disabled state until physically reset or commanded to reset by a supervisory controller. The module can also be configured such that a supervisory controller may enable or disable the observed circuit, as the result of an arc fault detection event or in cases where the supervisory controller decides that disabling the circuit is advantageous.

Within the vehicle electrical system, there are also potential configurations where alternating current and direct current circuits in a vehicle's electrical system are monitored by arc fault detection modules networked to a supervisory controller using the vehicle's Controller Area Network (or CAN bus). The supervisory controller is further networked to a number of remote contactors within the vehicle able to disable current flow through the monitored circuits. The arc fault detection modules sense, condition, and determine when an arc fault has occurred, transmitting this conclusion to the supervisory controller. The supervisory controller will then take action to address the arc fault detection event based on its programming to manage current flow in the vehicle electrical system by commanding the remote contactors.

Another potential configuration utilizes arc fault detection modules capable of independently disabling current flow on a circuit in combination with modules which transmit an arc fault detection event to the supervisory controller, which then uses remote contactors to disable current flow through the monitored circuit.

The vehicle electric system can comprise a supervisory controller networked to at least one remote contactor, a first circuit comprising a first module, and a second circuit comprising a second module.

The first circuit and the second circuit are selected among an alternating current circuit or direct current circuit. The first module comprises first processing logic and a first contactor configured to disable the first circuit independently of the supervisory controller when an arc fault is detected. The second module is configured to transmit arc fault detection data to a supervisory controller. The supervisory controller can be programmed to receive and process the transmitted arc fault detection data, and, when an arc fault condition is detected, the supervisory controller can be programmed to manage current flow in the vehicle electrical system by commanding at least one remote contactor to disable.

Additional objects and advantages will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the claimed invention.

Reference will now be made in detail to the examples which are illustrated in the accompanying drawings. Directional references such as "left" and "right" are for ease of reference to the figures.

To understand the basic components of an arc fault detection module, we can look to <FIG>, which is a block diagram showing the basic components and functions of an arc fault detection module with arc fault circuit interrupter (AFCI) capability. Similar to each arc fault detection module, it has a sensor attached to a monitored circuit <NUM>. To detect an arc fault condition the sensor signal must be conditioned using signal conditioning logic <NUM>, and also processed by an algorithm able to determine if an arc fault has occurred, in this case by a processing unit <NUM>. If an arc fault is identified, a contactor <NUM> (such as a relay) is opened, and a notification device <NUM> can communicate to other vehicle systems or telematics systems to inform them of the arc fault condition via the CAN bus <NUM>.

As seen in <FIG>,<FIG>, <FIG>, <FIG>, and <FIG>, which serve as examples of conceptual electrical and conventional vehicle layouts, these types of modules exist for both alternating current and direct current circuits.

There are a number of different configurations of an arc fault detection module <NUM>. One example is referred to as an arc fault detector (AFD). This includes sensing capabilities, stored signal conditioning logic and processing capability (such as a microcontroller or other device comprising a RAM, ROM, DRAM, ePROM, or other memory device configured with stored and executable programming) for determining if an arc fault condition has occurred and is installed to monitor the protected circuit. If an arc fault occurs, a notification is made to a supervisory controller, in this case the centralized ECU <NUM>. An alternate implementation would be to remove the processing unit from the arc fault detection module <NUM>, and to utilize the centralized ECU <NUM> to process the conditioned signal from the sensor monitoring the circuit. ECU <NUM> would coordinate control of numerous vehicle devices and ECU <NUM> would comprise processing and memory devices with stored programming commensurate with that coordinated control.

In all cases, to provide full arc fault circuit interruption (AFCI) capabilities, the arc fault detection module must be able to, directly or indirectly, command a contactor <NUM> (such as a relay) to open and stop current flow through the monitored circuit when an arc fault condition is identified. While the module can be fully autonomous in certain configurations, the existence of an arc fault condition can be transmitted both within the vehicle, as shown in the block diagram representation of an arc fault detection module which utilizes a central ECU <NUM>, as well as in the block diagram representation of an arc fault circuit interruption module with notification capabilities <NUM> and also in block diagram representation of an arc fault detection module which utilizes separate AC and DC ECUs in <FIG>, or even on to an external network, such as the Internet, as shown in the power distribution units for electric vehicles <NUM> and <NUM>. Instructions may also be received from the supervisory controller over the vehicle's internal network as shown by the arrows between the microcontroller <NUM> and DC-AFCI components <NUM>-<NUM> in <FIG>.

In order to demonstrate how the modules might be deployed within an electric vehicle, <FIG> shows a conceptual diagram of the vehicle's major systems. The system consists of a high voltage battery <NUM>, an electronic control unit <NUM>, a power distribution unit <NUM>, an on-board charger <NUM>, two inverter circuits <NUM> and <NUM>, and a low voltage load, <NUM>. Within the power distribution unit, there are arc fault circuit interrupters ("AFCls") <NUM>-<NUM> which communicate with a microcontroller <NUM> networked to the internet. External to the power distribution unit, the on-board charger <NUM> is also in communication with the microcontroller, as is the charging station <NUM> when the vehicle is charging. AFCI <NUM> terminates flow to the power distribution unit from the on-board charger if it detects and arc fault by opening contactors <NUM>, while AFCIs <NUM> and <NUM> terminate flow to motor <NUM> and <NUM> in the event of an arc fault condition by opening contactors <NUM> and <NUM>. AFCI <NUM> is used to protect low voltage loads in the vehicle <NUM> (such as low voltage motors, convenience features like radio, air conditioner or interior lights, and other components within the vehicle). Again, if an arc fault is detected contactors <NUM> open.

<FIG> is identical to <FIG> in most ways but provides more detail on the low voltage load configuration. It shows the DC-DC converter <NUM>, the 12V battery <NUM>, representative low voltage loads <NUM>-<NUM>, and communication flow back to the microcontroller <NUM>. The sensors are remote from the microcontroller, indicative of a distribution of components that aggregate into a more sophisticated arc fault detection module that a single system-wide arc fault circuit interrupter. The sensors of <FIG> can be tailored for the AC or DC loads that they are monitoring instead of trying to monitor both types of loads with a single AFCI. The sensors can also be tailored for the Voltage (12V, 48V, etc.). The signal conditioning of the arc fault detection module is likewise tailored.

<FIG> shows a conceptual diagram of a conventional vehicle's electrical system, showing the installation of arc fault detection modules which rely on a centralized ECU. DC arc fault detection modules <NUM>, and <NUM>-<NUM> along with AC arc fault detection modules are used to protect the vehicle from arc faults. Each of these communicates with the centralized ECU <NUM> which acts by opening contactors within the vehicle's electrical system to disable the circuit which has experienced an arc fault.

<FIG> shows a conceptual diagram of a conventional vehicle's electrical system, showing the installation of arc fault detection modules which can act independently of a central ECU (AFCI type modules). DC AFCI modules <NUM>, and <NUM>-<NUM> along with AC AFCI modules are used to protect the vehicle from arc faults. As seen in <FIG>, each of the AFCIs includes one or more notification devices for communicating an arc fault detection to the ECU or other components within the vehicle, to include telematics systems.

<FIG> shows a block diagram showing an alternative implementation of <NUM>. In <FIG>, instead of a single ECU <NUM> handling arc fault detection, as in <FIG>, direct current arc fault event responses are handled by controller <NUM> and alternating current arc fault event responses are handled by controller <NUM>.

Should an arc fault be detected by DC AFCI <NUM>, it acts to stop current flow and notifies the controller for DC arc faults <NUM> within the centralized ECU, of the arc fault event. If an arc fault is detected by AC AFCI <NUM>, it acts to stop current flow, and notifies the controller for AC arc faults <NUM> within the centralized ECU, which serves as the controller for AC arc faults in this implementation. The system is also protected by a number of DC arc fault detection modules <NUM>-<NUM> which rely on an external control unit for arc fault response. These modules notify controller <NUM> within the ECU if an arc fault event is detected, and controller <NUM> responds to address the fault. In <FIG>, we return to the conceptual diagram of a conventional vehicle's electrical system showing the use of separate controllers for direct current and alternating current arc fault event responses. Circuits within the system are protected by a mix of arc fault detection modules with full AFCI capability including notification (<NUM>-<NUM>), and several direct current arc fault detection modules which rely on an electronic control unit for response to an arc fault detection event. Should an arc fault be detected by DC AFCI <NUM>, it acts to stop current flow and notifies the controller for DC arc faults <NUM> within the centralized ECU, of the arc fault event. If an arc fault is detected by AC AFCI <NUM>, it acts to stop current flow, and notifies the controller for AC arc faults <NUM> within the centralized ECU, which serves as the controller for AC arc faults in this implementation. The system is also protected by a number of DC arc fault detection modules <NUM>-<NUM> which rely on an external control unit for arc fault response. These modules notify controller <NUM> within the ECU if an arc fault event is detected, and controller <NUM> responds to address the fault.

The disclosed arc fault detection module for a vehicle overcomes the limitations of fuses and circuit breakers by supervising the circuit and continuously checking to determine if the circuit is experiencing a normal arc condition, or an arc fault condition which must be addressed. Alternative devices are compatible with the teachings of this disclosure. As one example, a current detecting section having at least one output, wherein the current detecting section is structured to determine whether at least one signal based on a current measured from a DC supply line exceeds at least one corresponding predetermined threshold level and cause the at least one output to indicate that the threshold level has been exceeded. The module works with processing device structured to: (i) receive the at least one output, (ii) determine whether an arc fault in the DC electrical system has occurred based on at least the at least one output, (iii) determine an estimation of background noise based on at least one signal indicative of a current on the DC supply line, and (iv) adjust the at least one corresponding predetermined threshold level based on the estimation of background noise. Compatible with this disclosure, other methodologies for arc fault detection are outlined in <CIT>, <CIT>, <CIT> and <CIT>, assigned to the instant applicant. Consistent with the teachings herein, the processing device of the referenced patents can be integrated with the AFCI or can be remotely positioned. The example arc fault detection devices are not limiting. Other arc fault detection modules can be compatible with the teachings herein.

The arc fault detection module for a vehicle can either work independently or with other vehicle systems (such as the power distribution unit <NUM> and electronic control unit <NUM>) through the vehicles' internal network (Controller Area Network, or CAN bus) to perform four basic functions - sense, signal condition, process the conditioned signal, and act when an arc fault is detected.

A smaller arc fault detection module can be distributed around the vehicle and connected to individual loads or small clusters of loads as shown in <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. The smaller arc fault detection module can be more specialized, and as a result be less expensive than a centralized component. Additionally, the logic of the smaller arc fault detection module can be more closely tailored for the load, as by being designed for either a high or low voltage load, or a DC or AC current configuration. If a discrete arc occurs, the whole vehicle doesn't shut down, and the arc fault detector is more able to react in its intended environment for high or low voltages and DC or AC faults. Below are additional alternatives for actuating a contactor to interrupt a load or cluster of loads.

A module for detecting arc fault in in one of an alternating current circuit or a direct current circuit in a power distribution system of a vehicle can comprise an arc fault detection unit comprising one or more sensors configured for monitoring an alternating current circuit or a direct current circuit for signs of an arc fault and configured for outputting arc fault data; signal conditioning circuitry for receiving and translating arc fault data for processing; a processing unit connected directly or indirectly to the signal conditioning circuitry, the processing unit configured to receive arc fault data from the signal conditioning circuitry and configured to identify an arc fault condition; and a notification device connected to the processing unit, the notification device configured to notify a supervisory controller of an arc fault and configured to communicate other data to the supervisory controller, as shown in <NUM>.

The processing unit can be connected directly to the signal conditioning circuitry in the arc fault detection module as shown in <NUM>.

A notification device <NUM>-<NUM> can be directly connected to the arc fault detection module.

The processing unit <NUM> can be remote from the arc fault detection unit and communicate via the vehicle's Controller Area Network, or CAN bus as shown in <NUM>.

The notification device may be replaced by a contactor directly or indirectly connected to the processing unit <NUM>, with the contactor configured to interrupt a flow of current when the arc fault condition is identified.

The processing unit <NUM> can be a microcontroller, where the microcontroller is configured to command the notification device to indicate when a fault has occurred; and where the microcontroller is configured to issue commands to a contactor <NUM> to interrupt a flow of alternating current circuit or direct current through the circuit monitored by the arc fault detection module.

Alternatively, the processing unit can be a centralized electronic control unit <NUM>, where the centralized electronic control unit is configured to receive and process signal data from other arc fault detection modules and controllers connected to the power distribution system of the vehicle. The centralized electronic control unit is configured to receive and process the arc fault data and to determine when an arc fault condition has occurred, and transmit a command to a contactor <NUM> to interrupt a flow of alternating current circuit or direct current through the circuit monitored by the arc fault detection unit.

These modules can be configured for installation on either a direct current or alternating current circuit, including direct or indirect connections to a powered unit, such as an on-board charger <NUM>, an inverter <NUM>, or a DC-DC converter <NUM>.

Variants of the arc fault detection module <NUM> can be configured so they may act independently of other aspects of the vehicle's electrical system. These modules are configured to observe an alternating current circuit or a direct current circuit for signs of an arc fault and include the signal conditioning circuitry, processing logic and a contactor capable of disabling current flow to the observed circuit. When the processing logic determines an arc fault has occurred, it can take independent action to disable current flow through the circuit. The module will then maintain the circuit in a disabled state until physically reset or commanded to reset by a supervisory controller <NUM>. The module can also be configured such that a supervisory controller <NUM> may enable or disable the observed circuit, as the result of an arc fault detection event or in cases where the supervisory controller 104decides that disabling the circuit is advantageous.

Within the vehicle electrical system, there are also potential configurations <NUM> where alternating current and direct current circuits in a vehicle's electrical system are monitored by arc fault detection modules networked to a supervisory controller using the vehicle's Controller Area Network (or CAN bus). The supervisory controller <NUM> is further networked to a number of remote contactors within the vehicle able to disable current flow through the monitored circuits. The arc fault detection modules <NUM>-<NUM> sense, condition, and determine when an arc fault has occurred, transmitting this conclusion to the supervisory controller <NUM>. The supervisory controller <NUM> will then take action to address the arc fault detection event based on its programming to manage current flow in the vehicle electrical system by commanding remote contactors.

Another potential configuration shown in <FIG> utilizes arc fault detection modules capable of independently disabling current flow on a circuit <NUM>-<NUM> in combination with modules which transmit an arc fault detection event <NUM>-<NUM> to the supervisory controllers <NUM>-<NUM>, which then uses remote contactors to disable current flow through the monitored circuit.

A vehicle electric system can comprise a supervisory controller <NUM> networked to at least one remote contactor, a first circuit comprising a first module, and a second circuit comprising a second module.

The first circuit and the second circuit are selected among an alternating current circuit or direct current circuit. The first module comprises first processing logic and a first contactor configured to disable the first circuit independently of the supervisory controller when an arc fault is detected <NUM>. The second module <NUM> is configured to transmit arc fault detection data to a supervisory controller <NUM>. The supervisory controller <NUM> can be programmed to receive and process the transmitted arc fault detection data, and, when an arc fault condition is detected, the supervisory controller can be programmed to manage current flow in the vehicle electrical system by commanding at least one remote contactor to disable.

Claim 1:
A vehicle electric system comprising:
one or more circuits, the one or more circuits comprising a plurality of modules, each module of the plurality of modules (<NUM>; <NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>), comprising:
an arc fault detection unit (<NUM>) comprising:
one or more sensors configured for monitoring an alternating current circuit or a direct current circuit for signs of an arc fault and configured for outputting arc fault data, and
signal conditioning circuitry (<NUM>) for receiving and translating arc fault data for processing,
a processing unit (<NUM>); connected directly or indirectly to the signal conditioning circuitry (<NUM>), the processing unit configured to receive arc fault data from the signal conditioning circuitry and configured to identify an arc fault condition, and
a notification device (<NUM>) connected to the processing unit (<NUM>), the notification device configured to notify a supervisory controller (<NUM>; <NUM>; <NUM>, <NUM>) of an arc fault and configured to communicate other data to the supervisory controller, and
the supervisory controller (<NUM>; <NUM>; <NUM>, <NUM>) networked to the plurality of modules,
wherein the vehicle electric system is configured with a plurality of remote contactors,
wherein each module of the plurality of modules (<NUM>; <NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>) is configured to supervise a respective one of the alternating current circuit or direct current circuit to collect and process arc fault data;
wherein each module of the plurality of modules (<NUM>; <NUM>-<NUM>; <NUM>-<NUM>; <NUM>-<NUM>) is configured to transmit arc fault detection data to the supervisory controller (<NUM>; <NUM>; <NUM>, <NUM>); and
wherein the supervisory controller (<NUM>; <NUM>; <NUM>, <NUM>) is programmed to manage current flow in the vehicle electrical system by commanding one or more of the remote contactors to open, disabling current flow to the one or more circuits, when an arc fault condition is detected.