Abstract:
Power inverter equipment monitor/controller method and apparatus are described. The invented apparatus provides for the semi-automatic state steering and monitoring of an inverter/charger and alternator system. A flat panel user interface includes an array of switches, displays and indicators for establishing modes of operation of the system, for initializing operating parameters of the system and a connected battery, for establishing rates for the system&#39;s operation, permit the user to monitor the system&#39;s operating mode and charging data (including charging efficiency factor or CEF) while it is operating to charge the battery and to supply AC power to connected appliances. By the one of the preferred methods of the invention, ramping-up the alternator&#39;s output of current, sustaining the output until the voltage of the battery is acceptable, adjusting the output while maintaining the battery voltage at an acceptable level, reducing output until float level voltage is obtained and further adjusting output to maintain float level voltage to preserve the battery charge. By the other of the preferred methods, certain charge data related to the charging of the battery--including a present CEF, maximum amp-hour charge level capacity of the battery (AH CL capacity), and the present status of amp-hour charge level--are given and stored in memory, the battery is discharged, the lowest-recorded (LR) AH CL is recorded with recharge begins, completing the recharge and storing amount of amp-hours used to recharge, determining an intermediate CEF by dividing AH used-to-recharge battery by difference between the AH CL capacity and LR AH CL, averaging the present CEF with the intermediate CEF to produce a result which is stored in memory as the present CEF, and resetting present status to the AH CL capacity.

Description:
This application is a continuation application of copending application Ser. No. 08/760,944, filed on Dec. 9, 1996, now abandoned which is a continuation-in-part of application Ser. No. 08/300,979 filed on Sep. 6, 1994, which issued on Dec. 10, 1996 as U.S. Pat. No. 5,583,413. 
    
    
     BACKGROUND 
     The present invention relates generally to power conversion equipment such as inverter and battery charger systems. More particularly, the invention concerns method and apparatus for semi-automatically and remotely monitoring the performance of and controlling such systems. 
     Power conversion equipment such as power inverters and battery chargers are known to provide for the efficient charging and recharging of batteries of both the wet-cell and gel-cell, so-called deep-cycle type. These batteries typically have a twelve volt (12V) or 24V capacity. One of the best known battery chargers uses three cycles including a first for bulk charging, a second for absorption or acceptance charging and a third for float charging, preferably in the listed order. Additionally, a fourth cycle for equalizing the charge of the battery may follow the float charging cycle upon command of a user. 
     During the bulk charging cycle, most of the charging current available from the charger is delivered to the battery bank, until such time as the upper charge limit is reached, thereby producing a rapid charging of the battery. During the absorption charging cycle, the battery voltage is held at the upper charge limit and the charging current is gradually ramped down. 
     During the float charging cycle, the charging current is curtailed and the charger monitors the battery voltage while it drifts down from the upper charge limit. In the float charging cycle, a constant battery voltage is maintained below the gassing point but above the resting voltage of the battery of a fully charged battery. The battery charger only supplies charging current when necessary to maintain the battery voltage. During the float charging cycle, the full output of the battery charger is available to operate any AC appliances that may be connected to the inverter/charger system. 
     Finally, during the equalizing charging cycle, periodically equalization is accomplished by applying an equalization current to the battery. Such causes wet cell batteries to gas profusely, the beneficial effects of which are removal of residual lead sulfate, restoring all cells to the same potential and mixing up the electrolyte. 
     Those of skill in the art will appreciate that even such advanced inverter/charger systems have no provision for user-specified monitoring and controlling levels at a conveniently located flat panel user interface fittable in a console of a marine or recreational vehicle, or fixable within an alternative energy residence. 
     SUMMARY OF INVENTION 
     The invented monitor/controller provides for the semi-automatic state steering and monitoring of an inverter/charger of the type described immediately above. A flat panel user interface includes an array of switches, displays and indicators for establishing modes of operation of the inverter/charger, for initializing operating parameters of the inverter/charger and a connected battery, for establishing rates for inverter/charger operation, and permit the user to monitor the operating mode, the charging cycle, the charging rate, the charge level and the charging efficiency of the battery system (which includes the inverter/charger and the battery) while it is operating to charge the battery and to supply AC power to connected appliances or loads. 
     In its preferred embodiment, the apparatus of the invention provides both a numeric liquid crystal display (LCD) and multiple light-emitting diodes (LEDs) as front panel indications of the system&#39;s operation. By the one of the preferred methods of the invention, an alternator and an inverter/charger are connected to the battery. They are steered by the monitor/controller to ramp-up the charging current, maintaining the charging current at a given limit until an acceptance voltage level is reached, then maintaining the battery&#39;s voltage at the acceptance voltage by controlling the charging current as the battery and load needs dictate. After the charging current falls below a given limit for a defined period of time and battery is determined to be fully charged, the charging current is controlled to maintain a lower float voltage level well below the gassing point of the battery to preserve the battery&#39;s charge. 
     By the other of the preferred methods of the invention, certain charge data related to the charging of the battery--including a present charge efficiency factor (CEF), maximum amp-hour charge level capacity of the battery, and the present status of amp-hour charge level--are given and stored in memory, the battery is discharged and the present status is decremented, beginning recharge of battery and storing the present status as the lowest-recorded amp-hour charge level, continuing the recharge of the battery and measuring the amp-hours used to recharge the battery and storing into memory as amp-hours used-to-recharge, completing the recharge, determining an intermediate CEF by dividing amp-hours used-to-recharge battery by difference between the maximum amp-hour charge level capacity and the lowest-recorded amp-hour charge level, averaging the present CEF with the intermediate CEF to produce a result which is stored in memory as the present CEF, and resetting the present status of amp-hour charge level to the maximum amp-hour charge level capacity of the battery. 
     These and other objects and advantages of the invention will be more fully understood by reference to the accompanying drawings and the detailed description to follow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a system block diagram of the invented apparatus made in accordance with a preferred embodiment of the invention. 
     FIG. 2 is a schematic block diagram of the controller portion of the system illustrated in FIG. 1. 
     FIGS. 3A and 3B collectively are a high-level flowchart illustrating the first of the two preferred methods of the invention by which the controller operates. 
     FIG. 4 is a high-level flowchart illustrating the second of the two preferred methods of the invention by which the controller operates. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, the apparatus of the invention made in accordance with its preferred embodiment is indicated generally at 10. Apparatus 10 preferably includes a housing or enclosure 12 for electronic circuitry 14 (inside the housing and shown in FIG. 2). Preferably, housing 12 is lidded or closed by a flat-panel cover 16 providing an array of push-button switches such as 18a, 18b in the form of a molded keypad or keyboard 18, a display such as 41/2-digit numeric liquid crystal display (LCD) 20 and an array of light-emitting diode (LED) indicators 22. Those skilled in the art will appreciate that housing 12 may take any of a variety of shapes, sizes and configurations, within the spirit and scope of the invention. 
     Preferably, apparatus 10 is adapted for console mounting or retrofit within the control console of a recreational or marine vehicle--or the wall of an alternative energy residence--and within reach by a ribbon cable 24 and a phone line 26 to an outboard regulator circuitry 40 via an outboard amp-hour monitor circuitry 36. The apparatus controls or regulates an alternator 34 via regulator circuitry 40 to which the alternator is connected. Apparatus 10 is preferably connected via a phone line 28 to an inverter/charger 30 which in turn is connected to one or more batteries 32, 32a. Alternatively, battery 32a may be a DC load or alternative power source such as a solar panel. 
     An alternator 34 is connected to one or more batteries 32, 32a to provide DC current to charge the batteries. Preferably, the alternator includes a sensor to measure the current produced by the alternator. The alternator, inverter/charger, and batteries are usually part of the vehicle&#39;s or residence&#39;s power subsystem. 
     Moreover, a current and voltage sensor 38 is connected to the battery (or batteries) to provide a means of measuring the current flowing through the battery and voltage across the battery. The sensor is connected to amp-hour monitor circuitry 36, and they are in communication with a microcontroller (described later) to function as an ammeter to measure the current flowing through the battery and a voltmeter to measure voltage across the battery. Preferably, the sensor includes a 500 amp/50 millivolt (50 mV) dual-shunt (a dual-shunt is used in a system with two batteries). 
     A regulator circuitry 40 for regulating an alternator is connected to amp-hour monitor circuitry 36 and alternator 34. The regulator circuitry preferably includes a high side field-effect-transistor (FET) driver with a voltage doubler and an alternator current buffer. Regulator circuitry 40 also includes an enablement LED indicator 40a for indicating S whether the regulation function is enabled or activated and an intensity-variable drive LED indicator 40b for indicating the relative intensity of the drive current that the regulator uses to control the alternator&#39;s output of current. The primary purpose of these LED indicators in the preferred embodiment is for status information and trouble-shooting. 
     Front panel push-button switches such as 18a, 18b (of which, as illustrated, there are more than two in the preferred embodiment of the invention) permit selection of measured or derived system variable to be displayed on LCD 20, and facilitate manual user control of the mode of operation, e.g. inverter versus charger mode, of the vehicle&#39;s power subsystem. LED indicators 22 are used to indicate various user selections and operational modes, thereby augmenting 41/2-digit numeric LCD 20. 
     In accordance with the preferred embodiment of the invention, display options include voltage, amperage, amp-hours consumed, charging efficiency and various status indicators including AC power present and charge, acceptance and float modes of operation. Control options include idle mode load sensitivity selection, load-limiting power share AC current limit selection, set up, minimum fully battery voltage (acceptance voltage) selection, minimum fully charged current selection (fully-charged-indication current determined by a small percentage of the battery capacity), battery capacity selection, ambient temperature selection and start equalization selection. It will be appreciated that, within the spirit and scope of the invention, more or fewer, or altogether different, controls and indicators are contemplated. 
     Referring now to the more detailed schematic diagram of FIG. 2, the heart of electronic circuitry 14 is a crystal oscillator-driven microcontroller 42 such as an 80C552 microprocessor, an address latch 44, a read-and-write memory (RAM) 46, a read-only-memory (ROM) 47, a dip-switch array 48, an input/output (I/O) port 50, a display 52, and a keypad 54. Display 52 includes LCD display 20 and LED indicators 22. Keypad 54 includes molded keyboard 18 and push-button switches 18a, 18b. 
     The microprocessor executes instructions stored in the illustrated onboard ROM performs all switch scanning and display functions, including driving the various LEDs and the LCD (which are part of display 52). The microprocessor also is programmed to perform the monitoring and control functions described above, by suitable programming techniques. 
     Referring collectively to FIGS. 1 and 2, I/O port 50 provides a means of communication with devices outside of enclosure 12 via a ribbon cable 24 and phone line 26. The I/O port provides a connection of electronic circuitry 14 of the apparatus to amp-hour monitor circuitry 36, regulator circuitry 40 (preferably via phone line 28 and the amp-hour monitor circuitry), and inverter/charger 30. The inverter/charger is preferably connected via standard telephone twisted-pair cabling 26 and transmits various status information to the microcontroller 42 regarding the status of the battery charging condition. The inverter/charger also receives commands from the microcontroller (based upon the user&#39;s input) directing the inverter/charger to perform various tasks including entering equalization mode, activating/deactivating the charging function, and activating/deactivating the inverting (DC-to-AC conversion) function. 
     Referring collectively to FIGS. 1 and 2, the apparatus is used with a battery charging system that includes the battery charger (inverter/charger) 30 for storing AC-to-DC converted electric power in one or more batteries 32, 32a connected thereto. Battery 32 has a charge level that is measured in amp-hours and a charge capacity measured in kilowatt-hours (kWhrs). 
     The apparatus has current and voltage sensor 38 and amp-hour monitor circuitry 36 in which provides a means of measuring the current flowing through the battery and a means of measuring voltage across the battery. The apparatus includes the microcontroller 42 which is connected to sensor 38 and inverted/charger 30. Connected to microcontroller is a memory for storing various charging data including present charging efficiency factor, a lowest-recorded amp-hour charge level, an a maximum amp-hour charge level capacity of the battery. 
     The microcontroller calculates the charging efficiency factor (CEF) of the battery charging system and battery and calculates the present state or status of the charge level of the battery measured in amp-hours. During the recharge of the battery, the microcontroller factors in the CEF when calculating the present status of the charge level. The microcontroller reports the results of its calculations, the current flowing through the battery and the voltage across the battery using a display connected thereto. 
     A new CEF may be recalculated each time the battery is recharged; however, in the preferred embodiment, the CEF recalculation only occurs when the battery was discharged at least ten percent before recharge and the battery has been fully recharged based on a measurement of the battery capacity in kWhrs. The preferred embodiment has the threshold requirement for recalculation of CEF to prevent skewed results based on partial recharges. 
     The microcontroller calculates an intermediate CEF by dividing the number of amp-hour used to charge the battery by the difference between the maximum amp-hour charge level capacity and the lowest-recorded amp-hour charge level and then averaging the present CEF with the intermediate CEF to produce a result which is stored in the memory (RAM) 46 as the present CEF--the result becomes the present CEF. 
     The apparatus has a keypad 54 which is connected to and scanned by microcontroller 42 and based on the user input on the keypad different information is displayed including battery voltage, battery current, present CEF, and present status of the amp-hour charge level. 
     Furthermore, the apparatus can function as a remote controller distally connected to inverter/charger 30. The user may set various setup parameters to control the inverter/charger. Some of setup parameters include an acceptance voltage, a fully-charged-indication current, a maximum amp-hour charge level capacity, an idle mode sensitivity of the inverter/charger and a load-limit AC power share of the inverter/charger. Also, the user can activate the equalization mode or cycle of the inverter/charger. 
     The default for the idle mode in the preferred embodiment is 4 Watts which means that it takes a four watt (4 W) AC load to turn the inverter on from its low power idle mode. The purpose of the power sharing feature is to automatically reduce the charger output, and therefore the AC power consumption, if the load passing through the inverter&#39;s automatic transfer switch exceeds the setup value. This load management feature helps prevent AC supply breakers from tripping when the vehicle&#39;s electric systems are plugged into AC power and the charger and other loads all come on at once. 
     Referring now collectively to FIGS. 3A and 3B, the first of the preferred methods of the invention is illustrated by way of a flowchart. This is a method of regulating an alternator for use with a system that includes an alternator that supplies a variable current to a multi-cycle battery charger system connected thereto. The battery charger system includes a battery charger which is connected to a battery (to be charged) wherein the battery has a battery voltage that depends upon present charge condition of the battery. The voltage of the battery will be higher when the battery is fully charged than when the battery is discharged (i.e., less than fully charged). When the battery is fully charged, it has a maximum charge capacity measured in kWhrs. 
     This preferred method starts at 102 in FIG. 3A. At 104, the various settings are defined including alternator-current-limit (ACL), acceptance voltage (AV), fully-charged-indication current (FCI current) and float voltage (FV). The ACL is the maximum limit of the current that the alternator can produce and the AV is the voltage at which a battery is nearing its maximum charge but still accepting some charge (the default for the preferred embodiment is 14.4V for a 12V battery). The FV is less than the AV (default for the preferred embodiment is 13.5V for a 12V battery) and is the voltage that is sufficient to maintain the fully charged condition of the battery. The FCI current is preferably defined as a percentage of current of the battery capacity. At 106, these settings are stored into a memory connected to the regulator. 
     In the first preferred method of the invention, the voltage settings--including the AV and the FV--are modified or adjusted according to calculations based on several factors. The factors affecting the AV and the FV settings include the state of the charging cycle of the battery charger, the battery type (wet-cell or gel-cell) and the ambient temperature setting selected by the user. 
     In a system charging more than one battery, it is unlikely that all of the batteries will have equal charges and will recharge at the same rate. Also, over-charging a battery can cause damage and shorten the life of the battery. Therefore, the invention&#39;s preferred means of dealing with the danger of over-charging and the batteries&#39; different charging characteristics is to base all battery current and battery voltage measurements upon the charging current and the battery voltage of the battery with the highest measured voltage 107. 
     In this preferred method of this invention used with a system charging more than one battery, the battery with the highest voltage may be redetermined before each battery current and battery voltage measurement. This redetermination is done to prevent over-charging of a battery that recharges at a faster rate than the other batteries. 
     After the alternator starts 108, there is a short delay 110 to allow time for the engine driving the alternator to start and allow for a slow increase in the PWM (pulse width modulation) of the AC-to-DC power conversion of the charger. 
     Continuing with the first preferred method of the invention, the ACO (alternator-current-output) is ramped-up until the ACO reaches or is substantially equal to the ACL (alternator-current-limit). The ACL is the maximum current output of the alternator and the default in the preferred embodiment is 100 amps. During the ramping-up, a sensor measures ACO and the regulator raises the ACO to the ACL within a defined ramp-up time period which is defined in firmware (ROM) as twenty to thirty seconds in the preferred embodiment of the invention. Those skilled in the art will appreciate that the defined ramp-up time period may be adjusted to suit the need of any particular type of inverter/charger system or alternator without departing from the spirit and scope of the present invention. The ramping-up of the ACO avoids shock-loading the belts by abruptly starting with full alternator output. 
     After the ACO is ramped-up to the ACL, the charge cycle begins. During the charge cycle the ACO is held or sustained 114 at ACL as the BV (battery voltage) of the battery increases. The ACO of the alternator, CC (charging current) and BV (battery voltage) of the battery are measured. The charge cycle continues until the BV is substantially equal to an AV (acceptance voltage). In the preferred embodiment of the present invention, the default value of the acceptance voltage is 14.4V (or 24.8V for 24V systems) or the AV can be defined by the user. 
     After the AV is reached, the acceptance cycle begins. During the acceptance cycle, the ACO is adjusted 118 and the CC is measured. The acceptance cycle guarantees thorough charging by continuing to charge the battery until the CC becomes a small percentage of battery capacity (default for preferred embodiment is 2%). This small percentage of battery capacity defines a fully-charged-indication current (FCI current). The acceptance cycle continues until the CC is substantially equal to the FCI current 120. 
     The acceptance cycle is followed by the acceptance hold cycle. During the acceptance hold cycle, the ACO is periodically adjusted 122 to maintain BV at or above AV for a hold-time and the CC is measured. The acceptance hold cycle makes sure that the battery has accepted as much charge as it can. 
     In the preferred embodiment, the hold-time is between five to fifteen minutes if the CC is continuously less than or equal to FCI current and BV is continuously greater than or equal to AV; otherwise, hold-time is eighteen to thirty minutes. Those skilled in the art will understand that the hold-time may be modified--it can even be user defined without departing from the spirit and scope to the present invention. 
     Referring now to FIG. 3B, if BV falls below FCI current 124, then the charge cycle begins again by returning to the ramping-up step 112. When the acceptance hold cycle ends (without a repeating of above steps), then the float transition cycle begins. 
     The float transition cycle begins at 126. The ACO is reduced, CC and BV are measured. Reducing the ACO at this point in the battery charging procedure causes the BV to decrease. The float transition cycle is intended to provide a continuous (i.e., without disruption) alternator output during the cycle change from acceptance to float; thus, avoiding an abrupt transition between these voltages insures that electronic tachometers supplied from the alternator continue to work during the transition. Once BV is substantially equal to a FV (float voltage) 128, then the float cycle begins. 
     The purpose of the float cycle is to provide a small amount of current when necessary to maintain the charge of the battery. During the float cycle, the ACO is further adjusted 130 so that BV continues to be substantially equal to FV. Also, CC and BV are measured. ACO is zero if BV remains substantially equal to FV but ACO is greater than zero when necessary to maintain BV at FV. The FV is below the gassing point of liquid (wet-cell) batteries and above the resting voltage of a fully charged battery. The float cycle continues until the battery is discharged 132, the regulator or system is deactivated 132 or the battery charger enters another cycle upon the direction of the regulator 134. 
     Once the system has reached the float mode, the battery is fully charged and can be used by any attached AC appliances. Once the battery is discharged (preferably, a minimum discharge of ten to fifty percent and a maximum discharge of fifty percent), the process can be repeated to recharge the battery using an alternator in a quick and efficient manner. The above described method of the preferred embodiment of the invention allows the deep-cycle batteries of a vehicle (boat or recreational vehicle (RV)) or an alternative energy residence, a remote site to be recharged without the need for a readily available AC outlet. The regulator controlled alternator provides the AC to the battery charger in the manner described above to produce a quick and efficient charge of the deep-cell batteries. 
     After several recharges, it is advisable to equalize (the advantages of equalization will be described later) a wet-cell battery--as opposed to a gel-cell battery. The equalization of a battery should follow a recharge of a battery. The method of the preferred embodiment regarding the equalization follows the float cycle. 
     Continuing to refer to FIG. 3B, the regulator directs 136 the battery charger into an equalization mode. During the equalization mode the battery voltage is increased causing the battery bank to gas profusely and will accomplish the following: 
     (1) Removal of residual sulfate. Each time a battery is cycled and recharged, a small amount of sulfate is left on the plates. Over time, this gradual build-up of sulfate will compromise the performance of the battery. By applying an equalizing charge, this sulfate is returned back to the electrolyte, raising the specific gravity and fully exposing the active material of the plates. 
     (2) Bring all cells to the same potential. All lead-acid batteries are made-up of individual two volt cells. As the battery bank is cycled, slight differences in the cells results in different cell voltages, affecting the overall charge effectiveness. Equalizing will serve to bring all cells up to the same voltage and the electrolyte in each cell to the same specific gravity. 
     (3) Mixing up of the electrolyte. There is a tendency in the cell of a battery for the electrolyte to separate into layers of acid and water. The vigorous boiling of the battery during equalizing serves to physically mix the electrolyte. 
     During the equalization cycle, the ACO is varied 138 so that CC remains substantially equal to FCI current. Also, CC and BV are measured. After a set period of time or when BV is substantially equal to an equalization voltage (EV) 140, then the equalization cycle ends 142. The EV is preferably higher than the AV. 
     Referring to FIG. 4, a flowchart illustrates the charge efficiency factor (CEF) calculation method of the preferred embodiment. The process beings at start 150. Necessary charging data is provided 152 including present CEF, maximum amp-hour charge level capacity (max. A-H CL capacity) and present status of amp-hour charge level of the battery (present status of A-H CL). The charging data is stored 154 in a memory. 
     While the battery is discharging 156, the present status of A-H CL is decremented. Immediately before the battery is recharged, the present status of A-H CL is stored in memory as the lowest-recorded amp-hour charge level (L-R A-H CL) 158. While the battery is recharging, the amp-hours used to recharge the battery is measured and stored 160 as amp-hours used-to-recharge (A-H used-to-recharge). Upon completion of recharge of the battery 162, the A-H used-to-recharge reflects the amount of amp-hours required to fully recharge the battery. 
     After complete recharge of the battery, a new CEF is calculated to replace the old CEF to account for the changing, dynamic nature of a deepcycle battery&#39;s life. In this preferred method this invention, a new CEF may be calculated if the battery was discharged a given amount (between eight and twelve percent in the preferred embodiment) and all of the charge (measured in kilowatt-hours or kWhrs) is restored to the battery. 
     An intermediate CEF is determined 164 by dividing the A-H used-to-recharge by the difference of the maximum A-H CL capacity and the L-R A-H CL. After the intermediate CEF is determined, it is averaged 166 with the present CEF to produce a result that is stored 168 as the new present CEF. 
     After the new present CEF is calculated, the present status of A-H CL is set 170 to be equal to the max. A-H CL capacity because of the changing CEF of the battery charging system and the battery. The present CEF and present status of A-H CL is displayed 171. After the reset of the present status of A-H CL and display, the process ends 172. 
     While the present invention has been shown and described with reference to the foregoing preferred method and embodiment, it will be apparent to those skilled in the art that other changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.