Inverter with network interface

1. Field of the Invention

The present invention relates to inverters of the type suitable for inverting DC energy into single-phase AC energy, such as but not limited to the type suitable for inverting DC energy provided by a vehicle battery into single-phase AC energy suitable for powering a consumer electronic device.

2. Background Art

A vehicle electrical system typically relies upon an energy source to supply energy for powering a plurality of vehicle subsystems during normal vehicle operations. The amount of energy available from the energy source can vary during vehicle operation depending on the number of subsystems requesting energy and the ability of the energy source to maintain its energy output. Some vehicles employ an electronic control unit (ECU) to manage energy levels so that more critical subsystems are supplied energy before less critical subsystems, to insure limp-home capabilities, and to otherwise manage/regulate energy consumption.

The consumption of energy by the vehicle subsystems can be monitored by the ECU and tracked over time such that the ECU has an understanding of the amounts of energy required by the vehicle subsystems in order to operate under various operating conditions. The ECU can use this information and/or other strategies to selectively authorize one or more of the vehicle subsystem to consume energy (or otherwise regulate energy consumption) from the energy source. This may include the ECU exchanging messages and other data through a vehicle bus or other vehicle-based medium with the vehicle subsystems, or an associated controller, in order to selectively enable or disable (or limit) the vehicle subsystems.

The present invention is pointed out with particularity in the appended claims. However, other features of the present invention will become more apparent and the present invention will be best understood by referring to the following detailed description in conjunction with the accompany drawings in which:

FIG. 1 illustrates a vehicle electrical system in accordance with one non-limiting aspect of the present invention; and

FIG. 2 illustrates an inverter being configured to include a network interface in accordance with one non-limiting aspect of the present invention.

FIG. 1 illustrates a vehicle electrical system 10 in accordance with one non-limiting aspect of the present invention. The system 10 may include an energy source 12 for providing energy to a plurality of vehicle subsystems 14 where at least one of the subsystems is an inverter 16 configured to output single-phase AC energy to a consumer electronic device or other AC operable device 18 . An electronic control unit (ECU) 20 may be included to regulate and/or otherwise manage energy consumed from the energy source 12 by the vehicle subsystems 14 and inverter/device 16 , 18 . A vehicle network 22 , such as but limited to a Controller-Area Network (CAN) or Local Interconnect Network (LIN) bus, may be used to facilitate message and other data exchange between the ECU 20 and the vehicle subsystems 14 , inverter 16 , and AC device 18 .

The ECU 20 may be configured to execute any type of load control strategy, such as but not limited to a load shedding strategy of the type that controls energy consumption based on energy available from the energy source 12 and the functionality of vehicle subsystem 14 , 16 requesting energy such that more critical vehicle subsystems 14 , 16 are powered before less critical subsystem. The load shedding strategy may operate in real-time so that the ECU 20 can continuously enable, disable, and otherwise manage energy consumed by the vehicle subsystem 14 , 16 according to the amount of energy currently available from the energy source 12 or likely to be available within the future. This may include disablement of less critical subsystem 14 , 16 when energy levels run low, implementing limp-home functionality when energy levels are critically low, and/or otherwise specifying energy consumption limits.

The energy available from the energy source 12 may be dependent on the vehicle and its configuration for charging the energy source 12 and the configuration of the energy source 12 to maintain/distribute energy. For example, if the energy source 12 is a DC battery, capacitor, or other passive storage device charged by a vehicle alternator (not shown) or if the energy source is a fuel cell or other renewable energy source (not shown), the amount of available energy may fluctuate depending on ambient temperature, starter motor “cranking” state, vehicle payload (weight), switching on and off of energy consuming devices, and any number of other operating conditions that may change the amount of current drawn from the energy source 12 by various vehicle subsystems 14 , 16 .

The present invention, however, is not intended to be limited, unless otherwise noted, to any particular energy source 12 or means for charging the energy source 12 . The present invention full contemplates to the use of any energy source 12 having capabilities for providing a DC voltage to the inverter 16 in a manner sufficient of the inverter to output a single-phase AC voltage of the type suitable for powering most consumer electronic devices, e.g., 110/120/220V ac at 50/60 Hz. The inversion performed by the inverter 16 may be accomplished with any suitable inverter configuration. FIG. 2 illustrates the inverter 16 contemplated by one non-limiting aspect of the present invention being configured to include a network interface 30 to support message exchange with the ECU 20 and/or other devices connected to the vehicle network 22 .

The network interface 30 may be configured to allow the inverter 16 to interface with the ECU 20 through an exchange of one-way or two-way messages and according to any suitable protocol. The exposure of the inverter 16 to the ECU 20 can be helpful in allowing the ECU 20 to control energy consumption of the inverter 16 , and in some case, to set operating controls for the inverter 16 according to load shedding and other control techniques used by the ECU 20 to manage energy consumption of the vehicle electrical system 10 . The network interface 30 may be configured to send and/or receive messages over the vehicle network 22 according to any desirable architecture, such as but not limited to that required to support local interconnect network (LIN) version 2.1.

The network interface 30 may be connected to a primary stage microcontroller 32 used to control a primary stage wherein the DC battery voltage is boosted to a greater DC voltage. The primary stage may include a DC/DC converter 34 configured to boost a DC voltage from the energy source 12 prior to inversion by a DC/AC inverter 36 included in within a secondary stage. The DC/DC converter 34 may be configured as a push-pull converter where a chopper 38 operates in response to related DC/DC control signals to control switching operations of switching elements (not shown) that operate in cooperation with a transformer 40 to output a boosted DC voltage to a rectifier 42 where it is rectified into the boosted DC output voltage provided to the DC/AC stage. While the push-pull configuration is illustrated, the present invention fully contemplates the use of other configuration for the primary stage.

The DC voltage output from the primary stage may be inverted in the secondary stage to the single-phase AC voltage used to power the AC device 18 . A full-bridge inverter 46 may be used to invert the DC output from the primary stage according to control a number of switching devices operable in response to DC/AC control signals received from a secondary stage microcontroller 48 . The DC/AC control signals may be set to invert the DC output to any suitable single-phase AC voltage. Optionally, the secondary controller 48 may select the AC voltage and frequency depending on the connected device 18 , such as by user input and/or wireline or wireless communication with the device 18 .

An opto-isolator 50 may be included between the primary and secondary stage microcontrollers 32 , 48 . The opto-isolator 50 may be of the type that allows optical data signals to be transmitted between the microcontrollers 32 , 48 without requiring the microcontrollers 32 , 48 to be electrically connected to each other. The configuration of primary and second side windings of the transformer 40 may cooperate with the opto-isolator 50 to facilitate electrically isolating the primary microcontroller 32 from the secondary microcontroller 48 . This isolation can be helpful with the electronic communications carried out through the network interface 30 since it prevents interference caused by the switching operations of the second stage from interfering with communications taking place on the vehicle network 22 .

The primary and secondary stages may include sensors or other feedback to facilitate monitoring and controller related switching operations and/or to facilitate implementing energy consumption strategies. The primary microcontroller 32 is shown to receive a battery voltage value and a primary temperature value. The battery voltage value is used to represent the DC voltage input to the primary stage and to facilitate related controls to insure the desired DC output voltage is provided to the secondary stage for the given DC input voltage. The primary temperature value represents a temperature of the primary stage and may be used by the primary microcontroller to control automatic shutdown and/or output reductions in the event the temperature rises above a desired operating range. The secondary microcontroller 48 includes similar feedback values to facilitate similar operations. The secondary microcontroller may include an additional short circuit sensor to sense shorts that occur within the AC device 18 and/or though an outlet (not shown) used within the vehicle to removably connect the AC device 18 .

As illustrated, the network interface 30 exchanges signals between the vehicle bus 22 and the primary microcontroller 32 . The primary microcontroller 32 may then issue related messages or route the received messages, if needed, through the opto-isolator 50 in order to maintain electrical isolation from the stages. The secondary microcontroller 48 may issue messages to the primary microcontroller 32 for communication to the ECU 20 . For example, the secondary stage microcontroller 48 may determine an energy demand of the attached load 18 and issue a related message to the primary controller 32 to request the energy necessary to power the load 18 . The request may specify voltage levels, power levels, and/or desired frequency for the single-phase AC output. The primary microcontroller 32 may then communicate this request to the ECU 20 for processing. The ECU 20 may respond with an authorization message authorizing output of the requested energy demand or some percentage thereof depending on the parameter set by the load shedding strategy.

The ability of the ECU 20 to transmit messages to, and in some cases, receive messages from one or both of the primary and secondary microcontrollers 32 , 48 can be beneficial in allowing the ECU 20 to control any number of operations of the inverter 16 . The ECU 20 , for example, may be configured to prevent inverter operations until an ignition is changed from an ‘off’ position to an ‘on’ position (accessory power and/or engine running) and/or while an engine (not shown) is stopped as a part of a stop/start strategy, such as the type used with hybrid electric vehicles where the engine is stopped under certain circumstances without requiring the ignition to be turned to the off position. The ECU 20 may require the inverter 16 to request start, stop, and modified operations with corresponding message transmissions, such as to require connection of authorized load 18 before inverter 16 operations are permitted, as opposed to always making energy available from the inverter outlet. The ECU 20 may also transmit messages to shutdown or modify inverter operations, such as upon the ignition turning from the on position back to the off position or upon changes in the load shedding strategy. Optionally, the inverter 16 may retain some control over its own operations, such as by delaying shutdown for a period time, e.g. five minutes, after receipt of a shutdown message from the ECU 20 .

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale, some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention. The features of various implementing embodiments may be combined to form further embodiments of the invention.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.