Abstract:
A charging system for a battery of a vehicle comprises an electrical interface module that includes first and second electrical interfaces. An inverter module communicates with the electrical interface module and the battery and has a first state and a second state. In the first state, the inverter module allows the battery to be charged through the first electrical interface when a voltage source is connected to the first electrical interface, the vehicle is off, and a charge level of the battery is less than a threshold. In the second state, the inverter module allows the battery to provide power to the second electrical interface when a voltage source is not connected to the first electrical interface, the vehicle is on, and/or the charge level of the battery is greater than or equal to the threshold.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a vehicle electrical system, and more particularly to interfacing with a vehicle electrical system through an inverter. 
   BACKGROUND OF THE INVENTION 
   Automotive vehicles typically include an exhaustible electrical power source. The power source, such as a DC voltage battery, provides electrical energy to assist in the starting of the vehicle. After the vehicle starts, other elements of the electrical system provide any requisite electrical energy to the vehicle. The electrical system recharges the battery during vehicle operation. In this manner, the electrical charge of the battery is maintained at a sufficient level for starting the vehicle. 
   In certain circumstances, the charge of the battery may decrease to a level that is insufficient for starting the vehicle. For example, when the engine of the vehicle is off, the battery may power one or more electrical devices of the vehicle, such as a radio, headlights, and/or interior lights, thereby draining the charge of the battery. Extreme temperatures (high or low) and/or cycling may also degrade charge retention capabilities of the battery. One or more methods may be used to recharge the battery for purposes of starting the vehicle. For example, terminals of the drained battery may be connected to terminals of a second battery via a pair of cables. An electrical system of a vehicle that includes the second battery is used to start the vehicle that includes the drained battery. Alternatively, an external device may be used to charge the drained battery. 
   SUMMARY OF THE INVENTION 
   A vehicle comprises a power source for powering the vehicle. An electrical system is connected to the power source, the electrical system includes a battery. A first portion of the electrical system is electrically coupled to the battery and configured to supply electrical power from the battery to at least one electrical device associated with the vehicle. The electrical system further includes a second portion with an electrical interface module and an inverter module. The electrical interface module includes a first electrical interface and a second electrical interface. The inverter module is electrically coupled to the electrical interface module and the battery and is operable in a first state and a second state. In the first state, the inverter module permits the battery to be charged through the first electrical interface, the power source is off, and a charge level of the battery is less than a predetermined charge threshold. In the second state, the inverter module permits the battery to provide electrical power that is output from the electrical interface module through the second electrical interface when the source of electrical power is not coupled to the first interface, the power source is on, the charge level of the battery is greater than or equal to the predetermined charge threshold, and combinations thereof. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a functional block diagram of a vehicle electrical system interface according to the present invention; 
       FIG. 2  is a functional block diagram of the vehicle electrical system interface including an AC outlet interface according to the present invention. 
       FIG. 3  is a circuit schematic of an interface module according to the present invention; 
       FIG. 4  illustrates device connection configurations according to the present invention; 
       FIG. 5  illustrates AC outlet configurations according to the present invention; and 
       FIG. 6  is a flowchart that illustrates steps of a charging method according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module and/or device refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
   The present invention provides the capability of interfacing between a vehicle electrical system and conventional AC power outlets and power cords. For example, the vehicle electrical system may interface with home, commercial building, and/or other vehicle electrical systems. Referring now to  FIG. 1 , a vehicle  6  includes a vehicle electrical system  8 . The vehicle electrical system  8  includes a vehicle electrical system interface  10  according to the present invention. The vehicle electrical system interface  10  includes a battery management module  12 , an inverter module  14 , and an electrical interface module  16 . The interface  10  communicates with a vehicle control module  18  and a vehicle power source, such as a battery  20 . For example, the battery  20  is a DC voltage power source and can provide electrical power to a remainder  21   a  of the vehicle electrical system  8  (e.g. headlamps, interior lamps, instrument panel, radio, and window and seat motors) via a conventional wiring system  21   b.    
   In the present implementation of the invention, the interface  10  uses an existing vehicle communication network  22  (e.g. a data communication bus) to provide communication means between the battery management module  12 , the inverter module  14 , and the vehicle control module  18 . The electrical interface module  16  can communicate with an external power source  24 . For example, the external power source  24  may be an AC electrical system of a home or other building. Alternatively, the external power source  24  may be an electrical system of a second vehicle. Preferably, the electrical interface module  16  can communicate with the external power source  24  using conventional electrical communication means  26 . 
   The inverter module  14  allows charging of, and/or powering from, the battery  20  through the electrical interface module  16 . In other words, the interface  10  may charge the battery  20  from the external power source  24  through the inverter module  14 . Alternatively, the interface  10  may provide power to the external power source  24  and/or another external device from the battery  20 . The battery management module  12  communicates with the battery  20  to determine a charge status of the battery  20 . For example, the battery management module  12  may transmit information that indicates whether the battery  20  is charging or is at a full charge status to the inverter module  14 . The vehicle control module  18  communicates with one or more vehicle components to determine a status of the components and/or the vehicle. For example, the vehicle control module  18  can determine whether the vehicle is turned ON or OFF. In the present implementation, the vehicle is ON when the engine is running, thereby allowing the vehicle electrical system to provide power without draining the battery  20 . The vehicle is OFF when the engine is NOT running, and the only source of electrical power is the existing battery charge. The vehicle control module  18  transmits relevant status information to the inverter module  14  and the battery management module  12 . 
   The inverter module  14  operates according to the status information that the battery management module  12  and/or the vehicle control module  18  transmit to the inverter module  14 . For example, when the vehicle is turned ON, the inverter module  14  can permit the powering of external devices (i.e. devices that are not fixedly mounted to the vehicle and/or directly coupled to the battery  20  via the conventional wiring system  21   b ) from the battery  20  (i.e. discharging). The inverter module  14  may prevent the charging of the battery  20  when the vehicle is turned ON. Conversely, when the vehicle is turned OFF, the inverter module  14  may discontinue the powering of external devices from the battery  20  to prevent further draining of the battery  20 . In another implementation, the inverter module  14  may discontinue powering from the battery  20  when a charge status of the battery  20  decreases below a threshold. The inverter module  14  can permit the charging of the battery  20  from external devices when the vehicle is turned OFF. 
   Referring now to  FIG. 2 , an exemplary implementation of the vehicle electrical system interface  10  is shown in further detail. The battery management module  12  communicates with a first (e.g. positive) terminal  30  of the battery  20 . The second (e.g. negative) terminal  32  communicates with ground  34 . In this manner, the battery management module  12  is able to monitor the status of the battery  20  and communicate the information to the inverter module  14  as described above. The inverter module  14  can be a bi-directional inverter, which is able to receive and/or output an electrical signal. In the present implementation, the inverter module  14  sends/receives DC and/or AC electrical power signals. 
   The electrical interface module  16  is an AC power outlet that can include a first outlet  36  for discharging from the battery  20  and a second outlet  38  for charging to the battery  20 . The first outlet  36  is configured as a female socket interface and the second outlet  38  is configured as a male plug interface. In this manner, interchanging the charging/discharging operations may be prevented. One or more LED indicators  40  provide visible status information to a user. For example, the LED indicator  40  may indicate the charge status and/or fault codes. 
   In the present implementation, the inverter module  14  defaults to an output (i.e. discharging) mode. The inverter module  14  includes a sense circuit  42  that enables the inverter module  14  in the output mode or an input (i.e. charging) mode. When the sense circuit  42  determines that a connection is made to the second outlet  38 , the sense circuit  42  switches the inverter module  14  to the input mode. In the input mode, the battery  20  is in a charging status and the LED indicator  40  is ON. When the battery  20  is fully charged, the LED indicator  40  is OFF. 
   Referring now to  FIG. 3 , an exemplary implementation of the inverter module  14  and the sense circuit  42  is shown in further detail. In the output mode, a relay  44  is not energized, preventing electrical communication between the inverter module  14  and the second outlet  38  and allowing electrical communication between the inverter module  14  and the first outlet  36 . In other words, the inverter module  14  is configured to provide power to the first outlet  36 . 
   The sense circuit  42  includes capacitors C 1  and C 2 , a resistor R 1 , and diodes D 1  and D 2  and determines when a connection is made to the second outlet  38 . The capacitors C 1  and C 2 , the resistor R 1 , and the diode D 1  act as an AC active voltage divider. The capacitor C 1  exhibits a relatively large AC voltage drop, but does not consume power. During a positive half cycle of an AC signal (i.e. an AC signal received at the second outlet  38 ), the diode D 1  conducts current between the second outlet  38  and ground node  50 , charging the capacitor C 1 . During a negative half cycle of the AC signal, the diode D 2  conducts current between the second outlet  38  and ground node  52 . Those skilled in the art can appreciate that other suitable electrical devices may be used 
   In this manner, and in further combination with a resistor R 2 , the sense circuit  42  ensures that a sense input  54  of a microcontroller  56  is at ground potential when the second outlet  38  is not receiving an AC signal. When the sense input  54  is at ground potential, the microcontroller  56  turns transistor Q 1  OFF. When the transistor Q 1  is OFF, the relay  44  is not energized. Conversely, when the second outlet  38  is receiving an AC signal, the sense input  54  is at approximately 5V, DC. The microcontroller  56  turns transistor Q 1  ON. When the transistor Q 1  is ON, the relay  44  is energized, forming a connection between the second outlet  38  and an inverter AC stage  58 . In the input mode, the inverter AC stage  58  converts the AC electrical signal to a signal suitable for charging the battery  20 . In the output mode, the inverter AC stage  58  converts a DC signal from the battery  20  to an electrical signal suitable for powering external devices via the first outlet  36 . 
   The microcontroller  56  further operates according to vehicle and battery status information, in combination with the sense input  54 . For example, when the vehicle is turned OFF and the battery  20  is not at full charge, the microcontroller  56  energizes the relay  44 . When the battery  20  is at full charge, the microcontroller  56  may de-energize the relay to prevent overcharging, regardless of the status of the sense input  54 . The microcontroller  56  powers the LED indicator  40  accordingly. For example, the microcontroller  56  turns the LED indicator  400 N when the battery  20  is charging, and turns the LED indicator  40  OFF when the battery  20  is not charging. 
   Although the inverter module  14  is configured to de-energize (i.e. open) the relay  44  when the battery  20  is at full charge, damage to one or more circuit elements may prevent the relay  44  from opening. In this manner, the sense input  54  may continue to indicate 5V to the microcontroller  56  regardless of the mode of the inverter module  14 . The microcontroller  56  may turn the LED indicator  400 N and OFF to indicate a fault mode to the user. In another implementation, the microcontroller  56  may be external to the inverter module  14 . For example, either of the battery management module  12  and/or the vehicle control module  18  may incorporate one or more of the functions of the microcontroller  56 . 
   Referring now to  FIG. 4 , possible configurations between a vehicle  60  that includes the interface  10  and one or more external devices are shown. In a first exemplary use, the vehicle  60  uses a conventional electrical cord  64  to provide power to a second vehicle  66  that is also equipped with an interface  10 . For example, the vehicle  60  may charge a battery of the second vehicle  66 . Alternatively, the second vehicle  66  may charge the battery of the vehicle  60 . Those with ordinary skill in the art can appreciate that although the interface  10  associated with the vehicle  60  is configured to output A/C electrical power in the example provided, the interface  10  could be configured to output and/or receive DC electrical power. In a second exemplary use, the vehicle  60  receives power from the electrical system of a home  68  or other building to charge the vehicle battery or power other vehicle electrical devices. In a third exemplary use, the vehicle  60  provides power to an external electrical device  70  such as a power tool or radio. 
   Referring now to  FIG. 5 , outlet configurations of the above exemplary uses are described. A female outlet  80  is used to provide power to an external device  82  or charge/start a second vehicle. A male outlet  84  is used to receive power/charge from a home power outlet  86  and/or a second vehicle outlet  88 . Those skilled in the art can appreciate that other suitable configurations and/or uses are possible. 
   Referring now to  FIG. 6 , the present invention implements an exemplary charging method  100 . The method  100  starts in step  102 . In step  104 , a user plugs a power cord into an input interface of the vehicle and an output interface of a second vehicle or home. In step  106 , the method  100  determines the status of the vehicle. For example, the method  100  determines whether the vehicle is moving or ON. If true, the method  100  continues to step  108 . If false, the method  100  continues to step  110 . In step  108 , the method  100  initiates a fault code (e.g. a blinking LED indicator) and terminates in step  112 . In step  110 , the method  100  determines the status of the battery. For example, the method  100  determines whether the battery needs to be charged. If true, the method  100  continues to step  114 . If false, the method  100  continues to step  108 . 
   In step  114 , the method  100  switches the inverter relay to accept AC input (i.e. the input mode). In step  116 , the method  100  turns the LED indicator ON. In step  118 , the method  100  determines whether the battery is fully charged. If true, the method  100  continues to step  120 . If false, the method  100  repeats step  118 . In other words, the method  100  continuously lights the LED indicator and determines the charge status of the battery until the battery reaches full charge. In step  120 , the method  100  turns the LED indicator OFF. In step  122 , the method  100  switches the inverter relay to the output mode. In step  124 , the user unplugs the power cord. In another implementation, the LED indicator may blink if the power cord is not unplugged within a first period. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.