Line-interactive emergency-power apparatus with multi-chemistry adjustable charger and mode-selectable UPS / emergency-lighting / continuous output

Abstract

Technical field: emergency power supply apparatus integrating line-interactive UPS, battery charging, and emergency-lighting control. The invention addresses fragmentation of building back-up systems, chemistry-specific chargers, and lack of a continuous-duty portable source. An appliance comprises an AC input, a battery charger implementing constant-current / constant-voltage regulation with four independently adjustable set-points (charge-voltage, charge-current, charge- termination, discharge cut-off), an inverter with transfer switching, and a mode selector providing (i) UPS operation, (ii) emergency-lighting operation that asserts a lighting signal on loss of mains, and (iii) continuous-duty operation with the inverter enabled regardless of line presence. A unified multi-pin terminal consolidates mains input, load output, and the lighting signal. Analog protections include opto-isolated line-presence sensing, under-voltage cut-off with recovery, and current-transformer- based over-current shutdown. The arrangement reduces rewiring and component count, enables chemistry-agnostic deployment without firmware, and provides fast, isolated fault response in a compact enclosure.

Description

DescriptionTitle of Invention : Line-Interactive Emergency-Power Apparatus with Multi-Chemistry Adjustable Charger and Mode-Selectable UPS / Emergency-Lighting / Continuous Output[oooi] iTechnical Field

[0002] The disclosure relates to emergency and back-up electrical power systems.More particularly, it concerns a line-interactive uninterruptible power apparatus that integrates a multi-chemistry adjustable CC / CV battery charger with four independently settable parameters (charge voltage, charge current, chargetermination, discharge cut-off), a mode-selectable inverter / transfer control providing UPS, emergency-lighting, and continuous-duty operation, and a unified terminal interface carrying mains input, load output, and an isolated lightingcontrol signal. The apparatus further employs opto-isolated line-presence sensing, under-voltage cut-off with recovery, and current-transformer-based over-current protection, and is applicable to 12 V and 24 V battery systems across building services, commercial installations, and portable / field applications.Background Art

[0003] Uninterruptible power supply (UPS) equipment, emergency-lighting systems, and battery chargers are commonly implemented as separate subsystems in buildings and small facilities. Typical installations include: (i) a line-interactive UPS for computers and sensitive electronics; (ii) a dedicated emergency-lighting circuit to illuminate stairwells and common areas during grid outages; and (iii) battery chargers whose set-points depend on battery chemistry. In many deployments, these functions require distinct wiring and control interfaces.

[0004] Line-interactive UPS units have been widely described, including arrangements that transfer a load between the mains and an inverter using a relay so that the inverter engages upon loss of line. However, such systems have often been optimized for a single chemistry — commonly lead-acid — and provide no simple interface fordriving building emergency-lighting loads. Publications identified in the applicant’s review include, for example, US 5,436,816 and US7,141 ,892 (line-interactive transfer), which do not disclose chemistry-agnostic charging or an integrated emergency-lighting output.

[0005] Adjustable battery chargers are also known. For example, US 7,944,182 B2 limits charge current but employs a factory-fixed charge voltage; multi-chemistry chargers using microcontrollers have been described, such as WO 2010 / 034079, which recognizes multiple profiles but relies on digital control and does not provide a standard AC output for other loads. These approaches can increase cost and complexity and may not simplify integration with UPS and emergencylighting functions.

[0006] In the emergency-lighting branch, self-powered luminaires and similar devices typically energize only an internal lamp and do not expose an AC output suitable for general appliances or existing lighting circuits, which complicates consolidation with UPS or portable-source functions. Illustrative documents include US 4,410,835 and US 9,107,269 B2.

[0007] Portable power sources (“power banks”) have become prevalent as consumer accessories, underscoring demand for compact energy systems; however, consumer power banks do not generally integrate building-grade transfer, emergency-lighting signaling, or adjustable, chemistry-agnostic charging appropriate for facility use.

[0008] Against this backdrop, installations frequently face practical gaps: many midrange UPSs are tied to one battery chemistry; changing chemistries can require hardware replacement or firmware changes; emergency-lighting drivers are separate and require additional wiring; and line-interactive UPSs typically do not furnish a “continuous-duty portable source” mode when the mains is present. These recurring constraints indicate a need for equipment that unifies UPS functionality, building emergency-lighting interface, and portable continuous output while accommodating multiple chemistries with user-settable charge parameters and analog protections.Summary of Invention

[0009] In one aspect, the disclosure provides a line-interactive emergency-power apparatus that integrates: (i) a multi-chemistry adjustable charger implementing constant-current / constant-voltage (CC / CV) control with four independentlysettable hardware parameters (charge-voltage, charge-current, chargetermination, discharge cut-off); (ii) an inverter / transfer subsystem with a mode- selectable control providing UPS, emergency-lighting, and continuous-duty operation; and (iii) a unified terminal interface that consolidates mains input, load output, and a dedicated, isolated lighting-control conductor.

[0010] In certain embodiments, a line-presence detector generates an isolated logic signal (LINEJDK). Control circuitry is arranged such that, upon deassertion of LINEJDK, the apparatus concurrently (a) transfers the load from mains to the inverter and (b) asserts the lighting-control conductor to energize a building lighting branch. In continuous-duty mode, a forced-enable latch holds the inverter on irrespective of LINEJDK while under-voltage and over-current protections remain active.

[0011] The charger’s CV loop may use a precision reference with opto-isolated feedback; the CC loop may use a shunt-amplifier path. The four hardware setpoints permit field tuning without microcontroller firmware, accommodating Li-ion (e.g., NMC), LiFePO4, lead-acid (AGM / GEL), and Ni-Cd packs. Additional circuitry can provide under-voltage cut-off with hysteresis (auto-recovery) and current-transformer-based over-current shutdown. Thermal management can employ a ducted airflow path with dual fans.

[0012] Technical effects and advantages. The architecture (a) reduces wiring and installation complexity by unifying terminals and functions; (b) delivers coordinated, low-latency response to outages via concurrent transfer and lighting activation, mitigating flicker and delays; (c) enables chemistry-agnostic deployment through four independent hardware set-points, avoiding firmware tools and improving EMI / ESD robustness; and (d) adds a portable, continuous- duty source capability that typical line-interactive UPS units lack.

[0013] Other aspects. The invention further encompasses (i) a charger module with the four adjustable set-points and isolated CV / CC loops; (ii) a line-presence sensing module providing an isolated logic output; (iii) a unified terminal module mapping to AC-in, load-out, and lighting-signal conductors; and (iv) methods of operation corresponding to the UPS, emergency-lighting, and continuous-duty modes.Technical Problem

[0014] Conventional back-up power deployments for small facilities and buildings typically rely on three disparate subsystems — a line-interactive UPS for critical loads, a dedicated emergency-lighting solution, and a chemistry-specific battery charger. In practice, this architecture gives rise to the following interrelated technical problems:

[0015] Chemistry rigidity and field inflexibility. Mid-range UPS / charger platforms are often optimized for a single battery chemistry (e.g., VRLA). Altering chemistries (e.g., Li-ion NMC, LiFePO4, Ni-Cd) generally requires hardware replacement or firmware reconfiguration, leading to downtime and configuration risk.

[0016] Insufficient control over charge lifecycle parameters. Critical limits — constantvoltage level, constant-current limit, charge-termination threshold, and discharge cut-off — are frequently factory-fixed or only accessible via microcontroller firmware, limiting safe tuning to cell aging, temperature, and application-specific needs.

[0017] Lack of a simple, safe interface for emergency-lighting circuits. Typical UPS devices do not provide a unified, isolated conductor suitable for actuating an existing building lighting branch upon mains failure, forcing separate drivers, extra cabling, and coordination logic.

[0018] Absence of a true continuous-duty operating mode. Many line-interactive systems disable the inverter whenever the mains is present; using them as portable or always-on AC sources requires workarounds that compromise reliability or safety.

[0019] Protection latency and coupling gaps. Over-current at the inverter output and deep-discharge at the battery are sometimes handled via software polling or loosely coupled thresholds, which can permit damaging current, induce inverter chatter near low-voltage thresholds, or cause slow fault recovery.

[0020] Unreliable or non-isolated line-presence sensing. Ad-hoc mains detection without robust galvanic isolation can propagate noise into low-voltage domains, trigger nuisance transfers, or endanger control electronics.

[0021] Fragmented wiring and commissioning burden. Multiple boxes and terminals increase wiring errors, extend installation time, complicate troubleshooting, and introduce additional failure points.

[0022] Thermal and acoustic inefficiencies. Uncoordinated airflow across separate enclosures can create hot spots and excessive fan noise, degrading lifetime and user acceptance under sustained load.

[0023] Serviceability and EMI robustness concerns with firmware-centric designs.Field tools and updates add complexity; digital controllers can be susceptible to EMI / ESD-induced faults in electrically harsh environments.

[0024] Accordingly, there is a need for equipment that (i) accommodates multiple battery chemistries via field-adjustable charge / discharge parameters, (ii) provides a unified and isolated interface to energize building emergency-lighting circuits upon mains failure, (iii) offers a selectable continuous-duty mode alongside line- interactive UPS behavior, and (iv) achieves fast, deterministic protection and coherent thermal management — while reducing installation complexity and lifecycle cost.Solution to Problem

[0025] Conventional back-up power deployments for small facilities and buildings typically rely on three disparate subsystems — a line-interactive UPS for critical loads, a dedicated emergency-lighting solution, and a chemistry-specific battery charger. In practice, this architecture gives rise to the following interrelated technical problems:

[0026] Chemistry rigidity and field inflexibility. Mid-range UPS / charger platforms are often optimized for a single battery chemistry (e.g., VRLA). Altering chemistries (e.g., Li-ion NMC, LiFePO4, Ni-Cd) generally requires hardware replacement or firmware reconfiguration, leading to downtime and configuration risk.

[0027] Insufficient control over charge lifecycle parameters. Critical limits — constantvoltage level, constant-current limit, charge-termination threshold, and discharge cut-off — are frequently factory-fixed or only accessible via microcontroller firmware, limiting safe tuning to cell aging, temperature, and application-specific needs.

[0028] Lack of a simple, safe interface for emergency-lighting circuits. Typical UPS devices do not provide a unified, isolated conductor suitable for actuating an existing building lighting branch upon mains failure, forcing separate drivers, extra cabling, and coordination logic.

[0029] Absence of a true continuous-duty operating mode. Many line-interactive systems disable the inverter whenever the mains is present; using them as portable or always-on AC sources requires workarounds that compromise reliability or safety.

[0030] Protection latency and coupling gaps. Over-current at the inverter output and deep-discharge at the battery are sometimes handled via software polling or loosely coupled thresholds, which can permit damaging current, induce inverter chatter near low-voltage thresholds, or cause slow fault recovery.

[0031] Unreliable or non-isolated line-presence sensing. Ad-hoc mains detection without robust galvanic isolation can propagate noise into low-voltage domains, trigger nuisance transfers, or endanger control electronics.

[0032] Fragmented wiring and commissioning burden. Multiple boxes and terminals increase wiring errors, extend installation time, complicate troubleshooting, and introduce additional failure points.

[0033] Thermal and acoustic inefficiencies. Uncoordinated airflow across separate enclosures can create hot spots and excessive fan noise, degrading lifetime and user acceptance under sustained load.

[0034] Serviceability and EMI robustness concerns with firmware-centric designs.Field tools and updates add complexity; digital controllers can be susceptible to EMI / ESD-induced faults in electrically harsh environments.

[0035] Accordingly, there is a need for equipment that (i) accommodates multiple battery chemistries via field-adjustable charge / discharge parameters, (ii) provides a unified and isolated interface to energize building emergency-lighting circuits upon mains failure, (iii) offers a selectable continuous-duty mode alongside line- interactive UPS behavior, and (iv) achieves fast, deterministic protection and coherent thermal management — while reducing installation complexity and lifecycle cost.Advantageous Effects of Invention

[0036] Conventional back-up power deployments for small facilities and buildings typically rely on three disparate subsystems — a line-interactive UPS for critical loads, a dedicated emergency-lighting solution, and a chemistry-specific battery charger. In practice, this architecture gives rise to the following interrelated technical problems:

[0037] Chemistry rigidity and field inflexibility. Mid-range UPS / charger platforms are often optimized for a single battery chemistry (e.g., VRLA). Altering chemistries (e.g., Li-ion NMC, LiFePO4, Ni-Cd) generally requires hardware replacement or firmware reconfiguration, leading to downtime and configuration risk.

[0038] Insufficient control over charge lifecycle parameters. Critical limits — constantvoltage level, constant-current limit, charge-termination threshold, and discharge cut-off — are frequently factory-fixed or only accessible via microcontroller firmware, limiting safe tuning to cell aging, temperature, and application-specific needs.

[0039] Lack of a simple, safe interface for emergency-lighting circuits. Typical UPS devices do not provide a unified, isolated conductor suitable for actuating an existing building lighting branch upon mains failure, forcing separate drivers, extra cabling, and coordination logic.

[0040] Absence of a true continuous-duty operating mode. Many line-interactive systems disable the inverter whenever the mains is present; using them as portable or always-on AC sources requires workarounds that compromise reliability or safety.

[0041] Protection latency and coupling gaps. Over-current at the inverter output and deep-discharge at the battery are sometimes handled via software polling or loosely coupled thresholds, which can permit damaging current, induce inverter chatter near low-voltage thresholds, or cause slow fault recovery.

[0042] Unreliable or non-isolated line-presence sensing. Ad-hoc mains detection without robust galvanic isolation can propagate noise into low-voltage domains, trigger nuisance transfers, or endanger control electronics.

[0043] Fragmented wiring and commissioning burden. Multiple boxes and terminals increase wiring errors, extend installation time, complicate troubleshooting, and introduce additional failure points.

[0044] Thermal and acoustic inefficiencies. Uncoordinated airflow across separate enclosures can create hot spots and excessive fan noise, degrading lifetime and user acceptance under sustained load.

[0045] Serviceability and EMI robustness concerns with firmware-centric designs.Field tools and updates add complexity; digital controllers can be susceptible to EMI / ESD-induced faults in electrically harsh environments.

[0046] Accordingly, there is a need for equipment that (i) accommodates multiple battery chemistries via field-adjustable charge / discharge parameters, (ii) provides a unified and isolated interface to energize building emergency-lighting circuits upon mains failure, (iii) offers a selectable continuous-duty mode alongside line- interactive UPS behavior, and (iv) achieves fast, deterministic protection and coherent thermal management — while reducing installation complexity and lifecycle cost.Brief Description of Drawings

[0047] Conventional back-up power deployments for small facilities and buildings typically rely on three disparate subsystems — a line-interactive UPS for critical loads, a dedicated emergency-lighting solution, and a chemistry-specific battery charger. In practice, this architecture gives rise to the following interrelated technical problems:

[0048] Chemistry rigidity and field inflexibility. Mid-range UPS / charger platforms are often optimized for a single battery chemistry (e.g., VRLA). Altering chemistries (e.g., Li-ion NMC, LiFePO4, Ni-Cd) generally requires hardware replacement or firmware reconfiguration, leading to downtime and configuration risk.

[0049] Insufficient control over charge lifecycle parameters. Critical limits — constantvoltage level, constant-current limit, charge-termination threshold, and discharge cut-off — are frequently factory-fixed or only accessible via microcontroller firmware, limiting safe tuning to cell aging, temperature, and application-specific needs.

[0050] Lack of a simple, safe interface for emergency-lighting circuits. Typical UPS devices do not provide a unified, isolated conductor suitable for actuating an existing building lighting branch upon mains failure, forcing separate drivers, extra cabling, and coordination logic.

[0051] Absence of a true continuous-duty operating mode. Many line-interactive systems disable the inverter whenever the mains is present; using them as portable or always-on AC sources requires workarounds that compromise reliability or safety.

[0052] Protection latency and coupling gaps. Over-current at the inverter output and deep-discharge at the battery are sometimes handled via software polling or loosely coupled thresholds, which can permit damaging current, induce inverter chatter near low-voltage thresholds, or cause slow fault recovery.

[0053] Unreliable or non-isolated line-presence sensing. Ad-hoc mains detection without robust galvanic isolation can propagate noise into low-voltage domains, trigger nuisance transfers, or endanger control electronics.

[0054] Fragmented wiring and commissioning burden. Multiple boxes and terminals increase wiring errors, extend installation time, complicate troubleshooting, and introduce additional failure points.

[0055] Thermal and acoustic inefficiencies. Uncoordinated airflow across separate enclosures can create hot spots and excessive fan noise, degrading lifetime and user acceptance under sustained load.

[0056] Serviceability and EMI robustness concerns with firmware-centric designs.Field tools and updates add complexity; digital controllers can be susceptible to EMI / ESD-induced faults in electrically harsh environments.

[0057] Accordingly, there is a need for equipment that (i) accommodates multiple battery chemistries via field-adjustable charge / discharge parameters, (ii) provides a unified and isolated interface to energize building emergency-lighting circuits upon mains failure, (iii) offers a selectable continuous-duty mode alongside line- interactive UPS behavior, and (iv) achieves fast, deterministic protection and coherent thermal management — while reducing installation complexity and lifecycle cost.Fig.1

[0058] [Fig.1 ] is a front elevational view of an emergency-power appliance showing the enclosure, unified terminal interface, user selectors (MODE and LIGHT / UPS), status indicators, and front airflow openings.Fig.2

[0059] [Fig.2] is a side elevational view of the appliance highlighting the mounting features, heat-sink region, and fan aperture(s).Fig.3

[0060] [Fig.3] is an internal arrangement view (cutaway or top-down) depicting the placement of the charger module (AUX), inverter / control module (POWER CTRL), transfer relay, current transformer, battery bay / interface, and linear airflow path. Fig.4

[0061] [Fig.4] is an exploded perspective view showing the housing components, printed circuit assemblies, transformer(s), fans, terminal block, fasteners, and other mechanical parts prior to assembly.Fig.5

[0062] [Fig.5] is a system-level electrical overview diagram identifying functional blocks and interconnections, including: AC input and EMI filter / rectifier, CC / CV charger, battery, inverter full-bridge and step-up transformer, transfer / switching arrangement, unified terminal, line-presence sensing, under-voltage protection, over-current protection, and fan control.Fig.6

[0063] [Fig.6] is an alternate internal view illustrating cable routing and spatial relationships among the charger, inverter, relay, sensing modules, and cooling hardware.Fig.7

[0064] [Fig.7] is a block diagram of the AUX charger showing startup supply, flyback power stage, constant-current and constant-voltage regulation paths, and user- adjustable set-points (charge voltage, charge current, charge-termination, discharge cut-off).Fig.8

[0065] [Fig.8] is a detailed schematic of the AUX charger (e.g., controller IC, primary MOSFET, flyback transformer, RCD snubber, auxiliary supply winding, TL431 / optocoupler voltage feedback, shunt and amplifier current feedback, output filtering, and adjustment potentiometers).Fig.9

[0066] [Fig.9] is a block diagram of the POWER CTRL / inverter illustrating the PWM controller, gate-drive stages, full-bridge output, transfer relay drive, and protection / shutdown inputs (line-sense, UV-cutoff, over-current).Fig.10

[0067] [Fig.10] is a detailed schematic of the POWER CTRL / inverter showing the oscillator and error-amplifier network, complementary PWM outputs with deadtime, driver transistors, full-bridge MOSFETs, power transformer, snubber network, current-transformer rectifier and opto-isolated fault path, under-voltage comparator and threshold adjust, and relay driver.Description of Embodiments

[0068] An emergency power system designed to provide reliable and portable electricity under all conditions features four mechanical potentiometers (for constant charge voltage, constant current, full-charge ceiling, and discharge cutoff threshold), enabling direct support for NMC, LiFePO4, AGM / GEL, and NiCd chemistries without the need for a microcontroller. The unit’s five-pin J1 terminal, along with two independent three-position switches, offers the user three distinct operating modes — “Standard UPS,” “Emergency Lighting,” and “Permanent Power Bank” — without requiring any changes to power wiring. All components are housed in a compact enclosure with a linear airflow path and dual-fan cooling. Current sensing circuits (CT), low-voltage comparators, and grid-detection optocouplers provide multi-layer protection at low cost.

[0069] The proposed design simultaneously addresses the challenges of multichemistry charging, emergency lighting, and permanent output. The core innovation consists of three coordinated elements:2-1) Four-Parameter Adjustable ChargerFour mechanical potentiometers are mounted on the board:• ADJ_V = Constant charging voltage (CV), adjustable within the range of 13- 16.8 V• ADJ_I = Constant charging current (CC), adjustable within the range of 2-6 A • ADJ_VCH = Full-charge ceiling; the charger disconnects once the battery reaches this voltage• ADJJJVF = Discharge cut-off threshold (10-12 V) to prevent deep discharge

[0070] The combination of two feedback loops — voltage regulation via TL431 and optocoupler, and current control via shunt resistor and amplifier — enables realtime compatibility with NMC, LiFeP04, AGM / GEL, and NiCd batteries without the need for a microcontroller. The installer simply adjusts the onboard potentiometers, without modifying any software or hardware.

[0071] 2-2) Five-Pin Terminal + Two Three-Position SwitchesAll input and output connections are consolidated in terminal J1 : two AC input pins, two load output pins, and one lighting signal pin. Two mechanical switches located on the rear panel control the following functions:• MODE switch: In “UPS” mode, the inverter activates only during grid failure; in “Permanent” mode, the inverter remains continuously active.• LIGHT / UPS switch: In “UPS” mode, emergency lighting is disabled; in “LIGHT” mode, the signal pin (pin 3) connects to a wall switch, allowing standard lamps to be instantly powered by the inverter upon grid outage.

[0072] The user can switch the device between the following three operating modes simply by toggling two switches, without touching any power cables:1. Standard UPS - The load is powered by the grid until a power outage occurs.2. Emergency Lighting of the Building- Upon grid failure, building lights are instantly powered by the inverter.3. Permanent Portable Power Source (220 V AC)

[0073] 2-3) Power Architecture and Layered Protection

[0074] • EMI-filtered input, rectification and isolated flyback charger, internal 12V battery, boost converter, and full-bridge inverter using 100V MOSFETs.

[0075] • Current sensing via CT transformer, TL431 comparator for overcurrent and undervoltage, and optocoupler for grid detection; upon any fault, the inverter and relay are immediately disconnected.

[0076] • Extruded aluminum enclosure, one 80 mm fan at the front and one 60 mm fan on the heatsink; linear airflow keeps the temperature below 60 °C at 300 W output.

[0077] 3. Integrated Operation

[0078] 1. Grid Power Available:After EMI filtering, the AC power is directly supplied to the load (pins 1-2), and the flyback charger charges the battery with regulated voltage and current. The green LED (GP) indicates grid presence and active charging.

[0079] 2. Grid Power Failure:The resistive divider of 310 V DC shuts down; the grid-detection optocoupler releases the DPDT relay, and the TL494 controller is activated. The full-bridge inverter converts the battery voltage to 220 V AC and supplies the load without interruption.

[0080] 3. Emergency Lighting:If the LIGHT / UPS switch is set to LIGHT, the lighting signal pin is connected to a wall switch. Upon grid failure, standard building lamps are automatically powered by the inverter, maintaining illumination.

[0081] 4. Battery Protection:When the battery voltage drops to the threshold set on ADJJJVF, the TL431 conducts; transistor Q11 pulls the TL494 shutdown pin to ground, turning off the inverter and lighting the red UVF LED.

[0082] 5. Recovery:After grid power is restored or the battery is replaced, the battery voltage rises 0.1 V above the threshold; the protection circuit resets and output is reactivated.Main Power Cable 16 Operating Mode Switch 2 (switching between standard UPS and lighting UPS): Mode 1 : Standard UPS is active.Mode 2: Fighting UPS is active.Winding 17 OutputElectrical terminal (not related to light 18 Windingswitch)Fan 1 location 19 Device HousingFan 1 (is activated upon inverter startup) 20 ADJ-I sets the charge current level.Side frame 1 21 ADJ-PWM adjusts the inverter output voltage.Side frame 2 22 Inverter transformerSide frame 3 23 Battery inputBottom frame 24 Inverter switchesTop frame 25 Fan outputFan 2 location 26 ADJ-UVFFan 2 (automatically turns on via thermal 27 ADJ-Vswitch and enters the circuit when thecharging temperature exceeds 50°C)The battery is NMC 3s5p, but it can also be 28 ADJ-VCH adjusts the inverter output a 4S EFP battery, an FS NMC battery, or a voltage. Note: All ADJ components are lead-acid battery. potentiometers (variable resistors).Electrical Circuit 29 Operating mode change relay Operating Mode Switch 1 (located 30 Related to the charging circuit between the UPS and the inverter):In Mode 1, terminals 1 and 2 areconnected. This allows the main power inputto pass directly to the output.In Mode 2, terminals 2 and 3 areconnected. This occurs when main power isdisconnected — the system uses batterypower, which is converted by the inverterinto 220V AC and sent to the output.A short-circuit signal is used to notify thesystem that the operating mode has changed.31 Flyback charging block 56 Adj-PWM block• Adjusts the inverter output voltage.32 Adj-V block: 57 Protection block: prevents output current sampling block overcurrent by reading current via a CT (current transformer).33 Adj-V block 58 Inverter switch block34 AC input for main power 59 Battery switching block35 250V varistor for overvoltage protection 60 Adj-VCH block• This potentiometer is used to disconnect the battery from charging.36 NTC and resistor for suppressing initial 61 City power sampling blockcapacitor charging surge • Used to detect whether the city power is disconnected when operating in UPS mode.37 LC Filter38 Diode bridge for rectifying the input voltage39 Capacitor C2 is related to the filtercapacitor.40 Capacitor charging resistor R1441 Flyback control MOSFET42 Control IC U 143 Flyback control44 Shunt resistor for current sensing45 Optocoupler for voltage and currentregulation46 Snubber circuit47 Main flyback transformer (secondarywinding used to generate min and maxvoltages)48 Auxiliary winding49 Charger output filter and charger indicator50 Feedback block51 Shunt voltage is amplified by an amplifier52 Auxiliary charging circuit building blocks53 Power control circuit building blocks54 Inverter control block55 Adj-UVF block•When the battery voltage drops below adefined threshold, this section uses an opto- triac to shut down the inverter output.Table of Component Analysis and Circuit Function of AUX Charger Name of Component / Section Precise Function in the CircuitComponent / Section in Schematic The brain of the charger. This is a currentPWM Controller (Integrated U1 (OB2262MP) mode switching power supply controller IC. Circuit)Its function is to generate a PWM signal todrive MOSFET QI. By receiving feedbackfrom the output (via optocoupler U2), the ICadjusts the pulse width to ensure that theoutput voltage and current remain preciselyat the set values.Main Switch. This transistor is controlled by Power MOSFET QI (SVF12N60F) IC U 1 and switches on and off at a very highfrequency (tens of kilohertz), directingcurrent through the primary winding oftransformer Tl.**The heart of isolation and voltage High-Frequency Tl (EE2820) conversion. This transformer has three Transformerwinding:1. Primary (pins 1-2): Receives energy fromthe input and stores it in its magnetic field.2. Secondary (pins 6-7): Transfers the storedenergy to the output section and steps downthe voltage to the level required for batterycharging.3. Auxiliary (pins 4-5):After circuit startup, supplies the operatingvoltage for IC U 1.MOSFET Protection. When MOSFET QI Snubber Circuit D1, D3, R5 turns off, the energy stored in thetransformer's leakage inductance generates avery high and potentially destructive voltage.The RCD (Resistor-Capacitor-Diode)snubber circuit absorbs and controls thisexcess voltage to prevent damage toMOSFET QI. DI is a TVS diode thatprovides fast protection against extremelyhigh voltage spikes.These two resistors, with a very low value Primary Current Sense R12, R13 (0.1 ohm), are connected in parallel and Resistorsmeasure the current passing through theMOSFET. The voltage across them is appliedto the R.I SENSE pin of IC U1 to provideprimary-side overcurrent protection andcycle -by-cycle control.Isolated Communication Bridge. This Optocoupler (Optical U2 (PC817C) component transfers the fault signal from the Isolator)output (secondary) section to the control(primary) section without any directelectrical connection between the two. Thisisolation is essential for safety.These two resistors, with a very high Startup Resistors R4, R6resistance value (1 MQ). provide a weakcurrent path from the high-voltage input (DCbus) to charge capacitor C6 and supply theinitial startup voltage for IC U 1.After the circuit starts operating, the auxiliary Auxiliary Supply D4, C6, R7 winding of T1 generates a voltage. Thisvoltage is rectified by diode D4 and filteredby capacitor C6 to provide a stable supplyvoltage (VDD) for IC Ul. This method ismuch more efficient than continuouspowering through the startup resistors.Resistor R7 is also included in this path.R10 is the main gate resistor that controls the Gate Driver Circuit R8, R10 switching speed of the MOSFET. R8 is azero-ohm resistor that functions as a jumper.This diode (1N4148) is used for protection or Signal Diode D5signal shaping in the power supply orfeedback circuit.These resistors, together with optocoupler Primary Feedback Network R16, RllU2, form the feedback network on theprimary side and set the voltage at the F.Bpin for precise control of IC U 1.This capacitor is used either to filter noise in Filter / Bypass Capacitor C8the feedback line or as a bypass capacitor toenhance circuit stability.This capacitor (Y-Capacitor) connects the Y-Safety Capacitor CY1primary and secondary grounds for high- frequency signals to reduce common-modenoise and improve EMI (ElectromagneticCompatibility) performance.

[0083] General Operation of the Circuit (Flyback Charger)

[0084] 1. Startup: Upon power connection, current flows through resistors R4 and R6 to charge capacitor C6. When the voltage across C6 reaches the startup threshold of U1 , the IC powers on.

[0085] 2. Switching: U1 begins sending pulses to the gate of MOSFET Q1. Q1 switches on and off at high frequency.

[0086] 3. Energy Transfer: While Q1 is on, current increases in the primary winding of transformer T 1 , storing energy in its magnetic field. During this time, the output diode on the secondary side is reverse-biased.

[0087] 4. Energy Discharge: When Q1 turns off, the magnetic field collapses and induces a voltage of opposite polarity in the windings. This voltage forwardbiases the output diode on the secondary side, transferring the stored energy to the output capacitors and ultimately to the battery.

[0088] 5. Regulation and Control: The feedback circuit on the output side measures voltage and current, and sends an error signal via optocoupler U2 to the F.B pin of IC U1. U1 adjusts the pulse width to precisely regulate the output according to the values set by potentiometers ADJ_V and ADJJ (located elsewhere in the schematic).

[0089] Table of Component Analysis and Function in Inverter Control Circuit (Power CTRL)Name of Component / Section Precise Function in the CircuitComponent / Section in Schematic The beating heart of the inverter. This IC Controller U6generates two pulse-width modulation(PWM) signals that are complementary toeach other (Out A and OutB), used to drivethe power MOSFETs in the inverter’s outputstage. The IC also includes internal circuitsfor voltage regulation and protection.This resistor (RT) and capacitor (CT) are Oscillator R27, C15 connected to pins 6 and 5 of IC U6,respectively, and determine the operatingfrequency of the inverter. This frequency istypically 50 or 60 Hz.This potentiometer, together with resistor R3, Output Voltage Regulation ADJ_PWM forms a voltage divider from the IC’s precise Circuit (potentiometer) and reference voltage (Vref). By adjusting the R3 potentiometer, the reference voltage for theinternal error amplifier of U6 is set. Thisallows the user to precisely adjust andstabilize the inverter’s AC output voltage tothe desired value (e.g., 220 volts).Battery Undervoltage Protection Section (UVLO)This potentiometer allows the user to set the Low Voltage Threshold ADJ_UVF minimum allowable voltage for the battery Regulator (potentiometer) (e.g., 10.5 volts for a 12-volt battery).These two resistors sample the battery Battery Voltage Divider R59, R62voltage (V_Bat) and reduce it to ameasurable level for the comparator circuit.This component compares the sampled Comparator U9battery voltage with the voltage set byADJ_UVF. If the battery voltage dropsbelow the defined threshold, the output of thecomparator is activated.Protective Shutdown SectionIsolated communication bridge. When a fault Optocoupler U8(such as battery undervoltage) is detected bycircuit U9, the fault signal (UVF / OCF) turnson the internal LED of optocoupler U8. Thisactivates its phototransistor and sends asignal to pin 10 (Shutdown) of IC U6.Receiving a signal from optocoupler U8 on Immediate Shutdown Pin Pin 10 (Shutdown) on this pin causes the PWM outputs to shut U6down immediately and instantly. Thismechanism is the fastest way to stop theinverter during fault conditions and protectthe battery from deep and damagingdischarge.The LED connected to the UVF / OCF line Fault Indicator and Protector LED and ZD1 lights up during a fault, notifying the user ofthe condition. The Zener diode ZD1 alsoprotects the optocoupler input from excessivevoltages.

[0090] General Operation of This Section

[0091] 1. PWM Generation: IC U6 continuously generates PWM signals at a frequency determined by R27 and C15.

[0092] 2. Voltage Regulation: IC U6 compares the final inverter output voltage (via a feedback loop not shown in this part of the schematic) with the reference voltage set by ADJ_PWM, and adjusts the pulse width to keep the output voltage stable.

[0093] 3. Protection: The UVLO circuit constantly monitors the battery voltage. As soon as the battery voltage drops below the threshold set by ADJ JJVF, the protection circuit shuts down IC U6 via optocoupler U8, preventing damage to the battery.

[0094] Table of Component Analysis and Function in the Inverter Power Stage Name of Component / Section Precise Function in the CircuitComponent / Section in SchematicThese two lines transmit the PWM signals PWM Signal Inputs OutA, OutB generated by the controller IC (U6 orSG3525) to this section. The two signals arecomplementary to each other.These two transistor pairs (known as totemGate Driver Q5, Q7, Q2, Q4 pole or push-pull configuration) act ascurrent amplifiers. The weak PWM signalsfrom the controller IC cannot directly drivelarge power MOSFETs. These driversamplify the PWM signal and provide thenecessary current to quickly charge anddischarge the MOSFET gate capacitors. Thisis essential for fast switching and reducingthermal losses in the MOSFETs.The beating heart and driving force of the Power MOSFETs Q3, Q14, Q6, Q15 inverter. These four MOSFETs are arrangedin a full-bridge (H-Bridge) configuration.This setup allows the circuit to apply thebattery voltage (V_Bat) alternately in bothdirections across the primary winding oftransformer T2.Series Resistors (R30, R34, R48, R55): Gate and Pull-Down R30, R31, R34, R35, These resistors limit the input current to the Resistors R48, R54, R55, R56 MOSFET gates and prevent unwantedoscillations (ringing). Parallel Resistors(R31, R35, R54, R56): These pull-downresistors ensure that in the absence of a driversignal, the MOSFET gates are quicklydischarged to ground, keeping the MOSFETsfully turned off.This is a low-frequency step-up transformer. Power Transformer T2Its function is to increase the AC voltagegenerated in the primary winding (which isconnected to the battery voltage) to thestandard grid AC voltage (e.g., 220 volts) inthe secondary winding.This is a low-frequency step-up transformer. Snubber Circuit C16, R33Its function is to increase the AC voltagegenerated in the primary winding (which isconnected to the battery voltage) to thestandard grid AC voltage (e.g., 220 volts) inthe secondary winding.

[0095] General Operation of This Section (Full-Bridge Inverter):

[0096] 1. Phase One: The OutA signal is activated. Driver Q2 / Q4 turns on MOSFETs Q3 and Q15. Current flows from the positive terminal of the battery (V_Bat), through Q3, across the primary winding of T2 (e.g., from pin 1 to 3), and through Q15 to ground.

[0097] 2. Dead Time: For a few microseconds, all MOSFETs are turned off to prevent short-circuiting between the two bridge branches.

[0098] 3. Phase Two: The OutB signal is activated. Driver Q5 / Q7 turns on MOSFETs Q14 and Q6. Current flows from the positive terminal of the battery, through Q14, across the primary winding of T2 in the opposite direction (from pin 3 to 1), and through Q6 to ground.

[0099] 4. Repetition: This cycle repeats at a frequency of 50 or 60 Hz. The alternating current in the primary winding generates an alternating magnetic field, which in turn induces a sinusoidal or quasi-sinusoidal AC voltage at the transformer output.

[0100] A detailed analysis of the input components has been provided:Component in Function in Circuit Component NameSchematic These two terminals are the connection points AC input terminal acl, ac2of the circuit to the mains power (220V AC).A fuse is a critical protective component. If Fuse Fusethe circuit draws excessive current — due to ashort circuit or malfunction — the fuse blowsand disconnects the circuit, preventingdamage to other components and reducing therisk of fire.This component is a voltage-dependent Varistor 7D391resistor (Varistor), used to protect the circuit (MOV : Metal Oxideagainst high and sudden voltage spikes (power Varistor)surges). Under normal voltage conditions, itsresistance is very high. However, if the inputvoltage exceeds a certain threshold(approximately 390 volts in this case), itsresistance drops sharply, effectively shortingthe excess voltage to prevent damage to thecircuit.This is a Negative Temperature Coefficient Thermistor (Thermal NTC(NTC) resistor used to limit inrush current. At Resistor)the moment of power-on, the large capacitorC2 is discharged and draws a high current.When cold, the NTC has high resistance,which restricts this initial surge. After a shorttime, as current flows through it, the NTCheats up and its resistance drops significantly,allowing normal circuit operation withoutinterference.This is a common-mode noise filter. It Common-Mode Choke EFprevents electromagnetic interference (EMI) (Filter Inductor)from entering the circuit via the power lineand also blocks noise generated by thecircuit’s switching section from feeding backinto the power grid.This is a safety capacitor placed between the X-Capacitor (Filter CXtwo AC input lines. Its function is to filter Capacitor)differential-mode noise. Together with theinductor LF, it forms an effective EMI filter.This component is a full-wave rectifier. Its Diode Bridge DBfunction is to convert the incoming alternatingvoltage (AC) into a pulsed direct voltage(DC). The AC input is connected to the ~terminals, and the DC output is taken from the+ and - terminals.This is a high-capacitance electrolytic Bulk Capacitor C2capacitor used to smooth the pulsed DCvoltage output from the diode bridge. Itcharges during voltage peaks and dischargesduring dips, thereby providing a nearlyconstant and stable DC voltage to power thesubsequent stages of the circuit.This resistor is used to safely discharge the Bleeder Resistor R14electrical energy stored in the large capacitorC2 after the circuit is disconnected from thepower supply. This prevents high voltagefrom remaining across the input terminals,reducing the risk of electric shock.

[0101] Table of Component Analysis and Circuit Function of the Charge Cut-Off SystemComponent in Function in Circuit Component NameSchematic Main Charge Switch: This MOSFET P-Channel Power MOSFET Q10functions as a switch in the path between thecharger output and the battery (V_Bat). Whenturned on, it allows the charging current toflow; when turned off, it completelydisconnects the battery from the charger.The Brain of the Voltage Comparison Precision Voltage U7Section: This is a highly precise voltage Referencereference and comparator IC. It compares thesampled voltage from the battery with itsinternal reference voltage (typically 2.5 V).This potentiometer allows the user to Cut-Off Voltage Regulator ADJ_Vch precisely set the final maximum voltage that (Potentiometer) the battery should reach. By rotating it, theactivation point of comparator U7 is adjusted.This resistor network samples the battery Sampling Voltage Divider R52, R53, ADJ_Vch voltage (V_Bat) and scales it down to a lower,measurable level suitable for the input ofcomparator U7.This transistor is directly controlled by the Logic Driver Transistor QUoutput of U7. When the battery voltagereaches the preset threshold and U7 istriggered, the transistor turns on and activatesthe charge cut-off logic.This transistor controls the gate of the main MOSFET Driver Transistor Q12 MOSFET (Q10). Its on / off state determinesthe final status of the main charge switch.This transistor switches the charge status LED Driver Transistor Q9indicator LED (CH) on and off.This LED turns on while charging is in Charge Status Indicator LED (labeled CH) progress. When the battery is fully chargedand charging is cut off, the LED turns off.These two fuses are installed to protect the Battery Fuses FS1, FS2 battery and the circuit against suddenovercurrent or short-circuit conditions in thebattery path.This is an external control signal. When the Charge Enable Input V_CHsignal is active (High), it allows the circuit toperform charging. If the signal becomesinactive (Low), it turns off MOSFET Q10 viadiode D15 and stops charging, regardless ofthe battery voltage.

[0102] Overall Operation of This Section (Charge Cut-Off Logic):

[0103] 1. Start of Charging: At the beginning, the battery voltage is low. Comparator U7 is inactive, and transistor Q11 is off. This condition turns on transistor Q12.

[0104] 2. Main Switch Activation: When Q12 turns on, the gate of MOSFET Q10 is pulled to ground, turning Q10 on. As a result, the path between the charger andthe battery (V_Bat) is connected, and charging begins. Simultaneously, transistor Q9 turns on and activates the CH indicator LED.

[0105] 3. Reaching Final Voltage: As charging continues, the battery voltage rises.Once it reaches the threshold set by potentiometer ADJ_Vch, comparator U7 is triggered.

[0106] 4. Cut-Off Logic Activation: Activation of U7 turns on transistor Q11. This, in turn, switches off transistor Q12.

[0107] 5. Complete Charge Cut-Off: With Q12 turned off, the gate of MOSFET Q10 is no longer grounded and is pulled high through resistor R39. This turns off Q10 completely, disconnecting the charger from the battery. At the same time, Q9 turns off and the CH indicator LED goes dark, signaling that charging is complete.

[0108] Component Analysis and Circuit Function Table - Power Loss Detection (Vin Sense)Component in Function in Circuit Component NameSchematic These two terminals are the connection AC Input Terminal Acl, ac2 points between the circuit and the mainspower (220 V AC).These high-value resistors limit the current Current-Limiting Resistors R71, R73 from the high-voltage AC lines and enablesafe sampling of the mains power.This capacitor (known as an X-Capacitor) Noise Filter Capacitor C23filters high-frequency noise present on thepower lines.This diode protects the circuit against high Zener Diode (Voltage D21and sudden voltage spikes (power surges). It Protection)keeps the input voltage to the sensing circuitat a safe level.This diode rectifies the sampled AC voltage Rectifier Diode D22in half-wave form and converts it into apulsed DC voltage.This electrolytic capacitor smooths the Smoothing Capacitor C22pulsed DC voltage output from diode D22and converts it into a nearly constant DCvoltage. As long as the mains power ispresent, this capacitor remains charged.This resistor limits the current flowing Current-Limiting Resistor R68through the internal LED of optocouplerU11 to a safe and appropriate level.The heart of the isolation and signaling Optocoupler Ullcircuit. This component transmits a signalusing light and provides complete galvanicisolation between the high-voltage ACsection and the low-voltage control section.This isolation is essential for the safety ofboth the device and the user.

[0109] General Operation of This Section:

[0110] This circuit functions as a simple yet highly effective sensor:

[0111] 1. Normal Mode (Utility Power Available):

[0112] -The AC current passes through resistors R71 and R73 and is rectified by diode D22.

[0113] -Capacitor C22 smooths the rectified voltage, generating a stable DC voltage.

[0114] -This DC voltage causes current to flow through resistor R68, turning on the internal LED of optocoupler U11.

[0115] -The illumination of the LED activates the phototransistor on the opposite side of the optocoupler. This signal informs the main control unit (microcontroller or logic IC) that “utility power is healthy.”

[0116] In this state, the inverter remains off, and the load is directly powered from the utility grid via the bypass relay.

[0117] 2. Emergency Mode (Utility Power Failure):

[0118] - When utility power is lost, no AC voltage is present at the input.

[0119] - Capacitor C22 quickly discharges, and its DC voltage drops to zero.

[0120] - The current through the internal LED of optocoupler U11 ceases, turning the LED off.

[0121] - The LED turning off deactivates the optocoupler’s phototransistor. This change of state signals the main control unit that “utility power has failed.”

[0122] - The control unit immediately activates the inverter and commands the output relay to switch the load to the inverter output.

[0123] Component-Level Evaluation Table for Charger Output and Feedback StageComponent in Function in Circuit Component NameSchematic Output Rectification and Filtering Stage This is a high-speed, low forward voltage Schottky Rectifier Diode D2 (MBR20150) drop power diode. Its function is to rectifythe high-frequency AC voltage output fromthe secondary winding of transformer Tl.These two high-capacity electrolytic Main Filter Capacitors C4, C5 capacitors (1000pF / 25V) smooth the DCvoltage rectified by D2 and provide a stable,ripple-free DC voltage for battery chargingand powering the control circuits of thissection.This small ceramic capacitor (330pF) is High-Frequency Filter Clconnected in parallel with diode D2 and Capacitorfunctions as a snubber to suppress high- frequency noise caused by the diode’s fastswitching.GP is an LED that indicates the “Power Power Status Indicator GP (LED), Rl, R2 Good” status or the presence of chargersupply. R2 is the primary current-limitingresistor for this LED, and R1 is also placedin the same path.Constant Voltage (CV) Control SectionThis potentiometer allows the user to Output Voltage Regulator ADJ_V precisely adjust the final charging voltage (Potentiometer) (e.g., 13.8V for float mode).This resistor network samples the output Voltage Sampling Divider R9, R15, ADJ_V voltage and scales it down to a lower,measurable level suitable for the input ofcomparator U3.The brain of the voltage regulation loop. Precision Voltage Reference U3 (TL431) This is a programmable voltage reference ICthat compares the sampled output voltagewith its highly accurate internal reference(2.5V). When the output voltage reaches thepreset threshold, U3 begins conductingcurrent.Isolated Communication Bridge. When U3 Feedback Optocoupler U4begins conducting, current flows through theinternal LED of optocoupler U4, turning iton. This action sends an optical signal to theprimary side of the circuit (to controller Ul)to reduce the PWM pulse width and stabilizethe voltage.These components ensure the stability of the Voltage Loop Compensation R17, R18, C9 voltage feedback loop and prevent unwanted Networkoscillations in the output.Constant Current (CC) Control SectionMain Current Sensor. This is a very low- Shunt Resistor R20 (SHUNT) value resistor (0.0 IQ) placed in the mainoutput current path. The voltage across thisresistor, according to Ohm’s law (V = I xR), is directly proportional to the batterycharging current.Current Signal Amplifier. This op-amp Operational Amplifier (Op- U5A (Im358dr2g) amplifies the very small voltage generated Amp)across the shunt resistor R20 by thousandsof times, converting it into a usable voltagesignal for the control circuit.These two resistors determine the gain of Gain-Setting Resistors R21, R22 op-amp U5A.This potentiometer allows the user to set the Output Current Regulator ADJ_I maximum charging current. It generates a (Potentiometer) reference voltage to be compared with theamplified current signal (output of U5A).These resistors link the output of op-amp Current Loop Resistors R19, R24U5A to the overall feedback loop, which isconnected to optocoupler U4.Other Components These components are used to stabilize and Compensation Network R23, CIO filter the signal within the overall feedbackloop.These capacitors filter and stabilize the Bypass Capacitors C11, C12 supply voltage for op-amp U5A to ensure itsproper operation.This resistor is placed at the output of the Resistor R25op-amp and acts as a pull-down resistor oras part of a logic network for combiningvoltage and current signals.

[0124] General Operation of the CV / CC Charger CircuitThis circuit intelligently switches between two operating modes:1. Constant Current Mode (CC): At the beginning of charging when the battery is empty, the circuit injects the maximum current set by ADJ_I into the battery. In this mode, the voltage generated across shunt R20 is high, and the output of op-amp U5A controls the feedback loop This signal is transmitted via optocoupler U4 to the primary controller, instructing it to adjust the output power so that the current does not exceed the defined limit.2. Constant Voltage Mode (CV): As the battery fills, its voltage increases. When the voltage reaches the level set by ADJ_V, the precision comparator U3 is activated and takes control of the feedback loop. From this point onward, the circuit maintains a constant voltage, and the charging current naturally decreases as the battery becomes fully charged.In fact, both voltage and current loops operate in parallel, and whichever requires less output power (i.e., imposes a stricter limitation) takes final control of the circuit. This method ensures optimal and safe charging for the battery.Overload ProtectionThis circuit continuously monitors the inverter's output current and immediately shuts down the inverter if an excessive load is drawn, preventing damage to the MOSFETs and transformer.Component in Function in Circuit Component NameSchematic Overload Protection This circuit continuously Current Transformer CTmonitors the inverter's output current and (CT)immediately shuts down the inverter if an excessiveload is drawn, preventing damage to the MOSFETsand transformer.These resistors are connected to the output Burden Resistors R57, R67 terminals of the current transformer and convert theinduced current into an AC voltage. The magnitudeof this voltage is directly proportional to the outputload current.These four diodes convert the AC voltage generated Rectifier Diode Bridge D16, D18, D19, across the load resistors into a pulsed DC voltage. D20These resistors condition the rectified DC voltage Limiting / Divider R65, R66 for the input of optocoupler U10 and adjust the Resistorssensitivity of the protection circuit.Fault Signaling: When the load current exceeds the Fault Optocoupler U10 permissible limit, the generated DC voltage risessufficiently to illuminate the internal LED of theoptocoupler. This activates its phototransistor.This line is the output of optocoupler U10. When Fault Signal Output FLTU10 is activated, it generates a fault signal that issent to the shutdown circuit of the PWM controllerIC (U6), causing the inverter to immediately ceaseoperation.

[0125] Comprehensive Analysis Table of Output and Feedback Section Components of the ChargerComponent in Function in Circuit Component NameSchematic Output Rectification and Filtering Section This is a high-speed, low-voltage-drop power diode. Schottky RectifierD2 (MBR20150)Its function is to rectify the high-frequency AC Diodevoltage output from the secondary winding oftransformer Tl.These two high-capacity electrolytic capacitors Main Smoothing C4, C5 (1000pF / 25V) smooth the DC voltage rectified by CapacitorsD2 and provide a stable, ripple -free DC voltage forbattery charging and powering the control circuitsof this section.This small ceramic capacitor (330pF) is connected High-Frequency Filter Clin parallel with diode D2 and functions as a snubber Capacitorto eliminate high-frequency noise caused by thediode's fast switching.GP is an LED that indicates the "Power Good" Power Status Indicator GP (LED), Rl, R2 status or the presence of charger power. R2 is themain current-limiting resistor for this LED, and R1is also placed in this path.Constant Voltage (CV) Control SectionThis potentiometer allows the user to precisely Output Voltage ADJ_Vadjust the final charging voltage (e.g., 13.8 volts for Regulator (Potentiometer) float mode).This resistor network samples the output voltage Sampling Voltage R9, R15, ADJ_V and converts it to a lower, measurable voltage level Dividerfor the input of comparator U3.The brain of the voltage loop: this is a Precision Voltage U3 (TL431) programmable voltage reference IC. It compares the Referencesampled output voltage with its highly accurateinternal reference (2.5V). When the output voltagereaches the preset threshold, U3 begins conductingcurrent.Isolated Communication Bridge: When U3 begins Feedback Optocoupler U4 conducting, current flows through the internal LEDof optocoupler U4, illuminating it. This actionsends an optical signal to the primary side of thecircuit (to controller Ul), prompting it to reduce thePWM pulse width and stabilize the output voltage.These components ensure the stability of the Voltage Loop R17, R18, C9 voltage feedback loop and prevent unwanted Compensation Networkoscillations in the output.Constant Current (CC) Control SectionMain current sensor: This is a very low-value Shunt Resistor R20 (SHUNT) resistor (0.01 ohms) placed in the main outputcurrent path. The voltage across this resistor,according to Ohm’s law (V = I x R), is directlyproportional to the battery charging current.Current signal amplifier: This op-amp amplifies the Operational Amplifier U5A (Im358dr2g) very small voltage generated across the shunt (Op-Amp)resistor R20 by thousands of times, converting itinto a usable voltage signal for the control circuit.These two resistors determine the gain of the Gain-Setting Resistors R21, R22 operational amplifier U5A.This potentiometer allows the user to set the Output Current ADJJ maximum charging current. It generates a reference Regulator (Potentiometer) voltage to be compared with the amplified currentsignal (output of U5A).These resistors connect the output of the op-amp Current Loop Resistors R19, R24 U5A to the overall feedback loop, which is linkedto the optocoupler U4.Other Components These components are used to stabilize and filter Compensation Network R23, CIO the signal within the overall feedback loop.These capacitors filter and stabilize the supply Power Supply Bypass C11, C12 voltage for the op-amp U5A to ensure its proper Capacitorsoperation.This resistor is placed at the output of the op-amp Resistor R25and functions either as a pull-down resistor or aspart of a logic network for combining voltage andcurrent signals.

[0126] Overall Operation of the CV / CC Charger Circuit:

[0127] This circuit intelligently switches between two operating modes:

[0128] Constant Current Mode (CC): At the beginning of charging, when the battery is empty, the circuit injects the maximum current set by ADJJ into the battery. In this state, the voltage across shunt R20 is high, and the output of op-amp U5A controls the feedback loop. This signal is sent via optocoupler U4 to the primary controller, instructing it to adjust the output power so that the current does not exceed the defined limit.

[0129] Constant Voltage Mode (CV): As the battery fills, its voltage increases.When the voltage reaches the level set by ADJ_V, the precision comparator U3 becomes active and takes control of the feedback loop. From this point on, the circuit maintains a constant voltage, and the charging current naturally decreases as the battery becomes fully charged.

[0130] Both voltage and current loops operate in parallel, and whichever requires less output power (i.e., imposes a stricter limit) takes final control of the circuit. This method ensures optimal and safe charging for the battery.

[0131] Comprehensive Analysis Table of Output Switching Section Components and State LogicComponent in Function in Circuit Component NameSchematic Output Switching This component, which was also analyzed in the Feedback Optocoupler PCI (EL817) previous image, is part of the voltage feedbackloop. Its output transistor, in this section of theschematic, delivers the feedback signal to the PWMcontroller IC (U6).This diode is placed in parallel and in reverse Flyback Diode D7 (ln4148) polarity with the relay coil. Its critical function is toprotect the driver transistor (Q6). When Q6 turnsoff, the inductive nature of the relay coil generates avery high and destructive reverse-polarity voltage.Diode D7 short-circuits this voltage and dissipatesits energy.This is a power NPN transistor that functions as a Relay Driver Transistor Q6 (D882) switch to activate the relay. When a control signalfrom the logic section of the circuit is applied to theRLY line, the transistor turns on and provides thecurrent needed to energize the relay coil.This resistor limits the input current to the base of Base Resistor R28 (470 Ohm) transistor Q6 to a safe and appropriate level,ensuring proper saturation and preventing damageto the transistor.The heart of the output switching section. This is an Changeover Relay Relay (Relay- 12v) electromechanical switch that toggles the outputload (OUT1) between two sources: either the citymains input (AC2) or the inverter output (comingfrom transformer T2).Main interface of the device with the external Main Input / Output JIworld: ConnectorAC1, AC2 (Pins 4 and 5): Mains power inputKey (Pin 3): Signal input from external light switchOUT1 (Pin 1): Final output to the loadGND_OUT (Pin 2): Output ground / neutralThis component, placed in parallel with the relay Varistor or Snubber NTC1 contacts, is a protective element for suppressingelectrical arcs and noise caused by load switching(especially inductive loads).Mode SelectionThis three -pin connector is connected to an external Mode Selection Mode (Connector) switch to select the operating mode of the device Connectorbetween UPS mode and portable power supplymode.This line (connected to pin 2 of the MODE Mains Power Detection Vin Sense Output connector) indicates the status of the mains power Signal (fromUll) to this section.This PNP transistor implements the main logic for Main Logic Transistor Q8enabling or disabling the inverter (via generating (PMPTA92 / 2222A) the RLY signal) based on the status of the MODEswitch and the Vin Sense signal.This resistor network provides the necessary Q8 Base Bias Network R37, R45, R43 voltage and current for proper biasing of the base oftransistor Q8.This capacitor and diode form a simple low-pass Filter / Delay Network C17, D14 filter that prevents unintended activation of Q8 dueto noise or short glitches on the signal line.This resistor acts as the load resistor for transistor Q8 Collector Resistor R38Q8 and generates the RLY output signal.This PNP transistor activates a control signal or Secondary Logic Q13 (B772) supply voltage (VCC) based on the circuit’s logic Transistorstate. This is done to power other sections of thecircuit only when needed, in order to save energy.R47: Pull-up resistor for the base of QI 3. C21, QI 3 Bias and Filter R47, C21, C28 C28: Filter and bypass capacitors for stabilizing the Networkoperation of QI 3 and the VCC voltage.This diode is used for isolating or logically Signal Diode D23 (ln4148) combining signals (OR-ing), and it connects theVin Sense signal to another part of the logic circuit.

[0132]

[0133] Overall Operation of This Section (Mode Selection and Switching Logic)

[0134] This circuit intelligently operates based on the user's selection and the status of the mains power:

[0135] 1. UPS Mode (Pins 1 and 2 of the MODE connector connected):In this mode, inverter activation depends on the Vin Sense signal.Mains power ON: Vin Sense is Low. This keeps transistor Q8 OFF, the RLY line remains High, Q6 is OFF, and the relay stays in its default state (load connected to mains).Mains power OFF: Vin Sense goes High. This turns Q8 ON, pulls the RLY line Low, turns Q6 ON, and activates the relay. The relay switches the load to the inverter output.

[0136] 2. Portable Power Supply Mode (Pins 2 and 3 of the MODE connector connected):Pin 3 is connected to battery voltage (V_Bat), forcing Vin Sense to stay High permanently.This "tricks" the circuit into thinking mains power is always OFF.As a result: Q8 stays ON, Relay remains activated, The inverter continuously powers the load from the battery, allowing the device to function as a portable power source.

[0137] Low Battery Voltage Cutoff (ADJ_UVF)

[0138] 1- Circuit Function: This section turns off the inverter and source relay when the 12V battery voltage drops below a user-set threshold, preventing deep discharge and battery damage. Simultaneously, a red LED lights up to alert the user of the low voltage condition.

[0139] 2- Main ComponentsR67 = 47 kQ: Upper arm of battery voltage dividerR68 = 4 kQ: Middle arm of voltage dividerADJJJVF = 500 O potentiometer: Cutoff threshold adjustment (10 to 12V) U9 = TL431 : 2.5V reference comparatorC29 = 1 pF: Feedback loop stabilityD9 = 1 N4148 diode: Signal isolationLED_UVF (red) + R74 = 1 kQ: Low voltage indicatorQ11 = NPN transistor: Pulls TL494 PWM stop pin to groundR75 = 10 kQ: Pull-up resistor for TL494 stop pin

[0140] 3-Adjustment Method: Measure battery voltage. Rotate the ADJJJVF potentiometer to set the cutoff voltage (VJrip) between 10V (min) and 12V (max). Approximate formula:V_trip « 2.5 V x (R67 + R68 + ADJ_UVF) - (R68 + ADJ_UVF)

[0141] 4- Operating Modes

[0142] a) Battery voltage above V_tripDivider output > 2.5V. TL431 is off, Q11 is off, inverter is active. LED is off.

[0143] b) Battery voltage < V_tripTL431 conducts, Q11 saturates, TL494 stop pin is grounded. Inverter and source relay turn off, red LED turns on.

[0144] c) Recovery after battery chargingWhen battery voltage rises ~0.1V above V_trip, TL431 turns off; stop pin goes high, inverter turns back on. C29 prevents output flicker at threshold crossing.

[0145] 5- Summary: The ADJJJVF circuit provides reliable deep discharge protection for any 12V battery using a few inexpensive components and no microcontroller, with a warning LED to indicate status to the user.

[0146] It should be noted that the above descriptions are provided for further clarification and are not intended to be limiting. For example, the illustrative designs described above (or aspects thereof) may be used in combination. Furthermore, numerous modifications may be made to adapt to a particular situation or need without departing from the core design of the invention. The dimensions, types of materials, orientation of various components, and the number and positions of the described elements are intended to define parameters of specific illustrative designs and are by no means restrictive; they are merely exemplary embodiments presented as samples. Upon reviewing the above descriptions, many variations and refinements in the nature and scope of these claims will become apparent to skilled and forward -th in king professionals. Therefore, the scope of the invention should be determined with reference to the appended claims, along with the full range of equivalents encompassed by those claims.

[0147] For better understanding, identical reference numerals have been used as much as possible to designate identical elements that are common across the figures. It has been observed that incorporating features of one or more illustrative designs into other designs may be beneficial.

[0148] Although the foregoing relates to illustrative embodiments of the disclosed invention, many other designs may also be proposed without departing from the core scope of the invention, which shall be defined by the claims set forth below. All documents referenced herein are incorporated into this work with their respective citations, including priority documents and test methods, to the extent they do not conflict with this text. As is evident from the general descriptions and specific embodiments mentioned above, although the forms and formats of the disclosed information have been described and illustrated, various modifications may be made without departing from the nature and scope of the disclosed invention. Accordingly, the presentation of the above designs does not imply that the disclosure of the present invention is limited to these examples.

[0149] Some designs and features have been described using a set of upper numerical limits and a set of lower numerical limits. It should be noted that the range includes combinations of both values. For example, a combination of a lower value with an upper value, a combination of two lower values, or a combination of two upper values is considered, unless stated otherwise. Certain lower limits, upper limits, and ranges are presented in one or more of the claims below.Examples

[0150] The following non-limiting examples illustrate practical implementations and tests supporting the claimed apparatus. Unless otherwise indicated, values are nominal and may vary by ±10%. References to figures and modules (e.g., AUX charger, POWER CTRL, unified terminal J1) correspond to the specification. Nothing herein limits the claim scope.

[0151] Example 1 — 12 V LiFePO4(4S) appliance; UPS and emergency-lighting operation

[0152] **Objective.** Demonstrate multi-chemistry adjustability, line-interactive transfer, emergency-lighting signaling, and protections on a 12 V class unit («300 W AC).

[0153] **Set-points.**

[0154] * ADJ\_V (CV): 14.4 V

[0155] * ADJ\_I (CC): 5.0 A

[0156] * ADJ\_VCH (termination): 14.6 V

[0157] * ADJ\_UVF (discharge cut-off): 11.2 V (auto-recover at «11.3-11.4 V)

[0158] **Setup.**

[0159] * Battery: 4S LiFePO4pack, 20-40 Ah, with BMS.

[0160] * Load: 230 V, 200 W resistive bank on the load conductors of J1.

[0161] * Emergency-lighting: lighting branch routed via the dedicated signal conductor of J1 to a contactor coil (or wall-switch input), as per site wiring.

[0162] * Instrumentation: mains presence indicator (LINE\_OK), DC voltage / current logging at the battery, AC transfer observation at the load (oscilloscope or power analyzer).

[0163] **Procedure and observations.**

[0164] 1. With mains present, the transfer relay ties the load to mains; the AUX charger regulates at CC^CV with the above set-points.

[0165] 2. Simulate grid loss: the line-sense optocoupler de-asserts LINE\_OK, the relay transfers the load to the inverter, and the lighting signal on J1 is asserted; the stairwell lighting branch energizes. No perceptible flicker / reset was observed on the 200 W resistive load.

[0166] 3. Discharge continues until V\_BAT « 11.2 V, where the UV cut-off comparator hard-disables the inverter and annunciates UVF. After the pack rebounds above the hysteresis, the inverter auto-recovers.

[0167] 4. Restoring mains returns the relay to line; charging resumes automatically.

[0168] **Result.** The unit operated as a UPS, energized an existing lighting branch via the unified terminal without rewiring power cabling, and enforced chemistry-appropriate limits using four independent analog set-points.

[0169] ## Example 2 — Continuous-duty portable source mode (NMC 3S) and charger retune

[0170] **Objective.** Show re-tuning to a different chemistry and use as a continuous portable AC source with mains present.

[0171] **Set-points (3S NMC).**

[0172] * ADJ\_V: 12.6 V

[0173] * ADJ\_I: 6.0 A (per pack rating)

[0174] * ADJ\_VCH: 12.6 V (or pack-specific taper threshold)

[0175] * ADJ\_UVF: 10.5-10.8 V

[0176] **Procedure and observations.**

[0177] 1. Adjust the four potentiometers to the above values.

[0178] 2. Set the selectors to **continuous-duty**; the inverter runs regardless of mains presence, allowing the AC output to power a portable tool / load bank while the charger maintains the DC bus.

[0179] 3. With step changes from 100 W to 250 W, the CT-based OCP path remained inactive (proper headroom); transient recovery was stable with no controller latch-up.

[0180] **Result.** The same hardware served a different chemistry and use-case (portable source) by field-adjusting set-points and selector positions — no firmware or hardware change required.

[0181] ## Example 3 — Building retrofit: unified-terminal integration of lighting branch

[0182] **Objective.** Validate that the dedicated lighting conductor on J1 enables emergency-lighting behavior without rerouting the branch’s power cabling.

[0183] **Setup.**

[0184] * Existing stairwell lighting circuit with a control input (wall switch or control coil).

[0185] * The J1 lighting conductor wired to the control input through code-compliant isolation (contact / coil or optically isolated receiver).

[0186] **Procedure and observations.**

[0187] 1. With selectors in **emergency-lighting** mode and mains present, the stairwell lighting operates normally from the building supply.

[0188] 2. Upon mains loss, the appliance asserts the lighting conductor; the control input closes and the stairwell branch is energized from the inverter output through the transfer arrangement.

[0189] 3. Restoring mains clears the assertion; the branch reverts to normal supply.

[0190] **Result.** The retrofit achieved code-conscious behavior (line presence sensing, isolated signaling) using the unified terminal, eliminating a separate emergency driver box and reducing wiring points.

[0191] ## Example 4 — Protection validation (OCP, UV cut-off, line-sense)

[0192] **Objective.** Confirm deterministic hardware protections.

[0193] **Over-current protection (OCP).**

[0194] * Method: Step the AC load until exceeding the configured continuous rating by =20-30%.

[0195] * Observation: The current transformer secondary, via burden / rectifier / scaling network, drove the opto-isolated shutdown. The inverter controller latched off; upon load removal, normal operation resumed. Burden / scaling values were then tuned to allow expected inrush (e.g., incandescent) without nuisance trips.

[0196] **Under-voltage cut-off (UVF).**

[0197] * Method: With AC absent, discharge the battery toward ADJ\_UVF.

[0198] * Observation: At the programmed threshold, the comparator disabled the inverter. Automatic recovery occurred at «+0.1 V above the trip point (set by feedback network hysteresis), preventing chatter under marginal state-of-charge.

[0199] **Line-presence detection.**

[0200] * Method: Cycle the AC input with varied ramp rates and injected noise (EMI source).

[0201] * Observation: The high-impedance divider + rectifier + smoothing fed the optocoupler to produce a clean logic-level LINE\_OK; no false assertion / de- assertion was observed under conducted noise levels typical of commercial mains.

[0202] **Result.** Fault responses were hardware-fast and isolated, protecting semiconductors and batteries while avoiding oscillatory behavior.

[0203] ## Example 5 — 24 V variant for telecom / controls

[0204] **Objective.** Show scalability to a 24 V nominal system and applicability to plant batteries.

[0205] Set-points (24 V LiFePO48S illustration).

[0206] ADJ\_V: 28.8 V

[0207] ADJ\_I: 4.0 A (per battery spec)

[0208] ADJ\_VCH: 29.2 V

[0209] ADJ\_UVF: 22.4-24.0 V

[0210] Electrical changes.

[0211] Transformer turns ratio adjusted to deliver 230 Vac from a 24 V DC bus;MOSFET V\_DS and bulk capacitor ratings increased accordingly. Control topology and protection blocks unchanged.

[0212] **Result.** The architecture, protections, and unified terminal are conserved;only power-stage dimensioning changes, enabling a product family with shared control electronics.

[0213] Comparative Example (installation complexity)

[0214] Scenario. Conventional deployment using (i) a chemistry-specific UPS, (ii) a separate emergency-lighting driver, and (iii) a portable inverter.

[0215] Observation. Three enclosures, at least two separate AC terminations and one low-voltage control run; field change from VRLA to LiFePO4requires replacing or re-flashing the UPS charger. By contrast, the disclosed apparatus used one enclosure, one unified terminal (mains, load, lighting), and four hardware adjustments to retune chemistry; commissioning steps and wiring points were reduced.

[0216] Implementation notes (apply across examples)

[0217] * Isolation boundaries are maintained by the transformer(s) and optocouplers; creepage / clearance and earthing follow the applicable standards for the intended market.

[0218] * Indicator logic (POWER / GP, CH, UVF, FAULT) assists setup and service.

[0219] * Fans may be thermostatic or state-driven; linear airflow minimizes hot spots at sustained load.

[0220] These examples demonstrate that the claimed **four-parameter analog charger**, **tri-mode operation** (UPS I emergency-lighting I continuous-duty), **unified terminal with lighting signal**, and **layered analog protections** can be implemented with conventional components and procedures, providing chemistry-agnostic, installer-friendly performance in real-world scenarios.Industrial Applicability

[0221] The invention is susceptible of industrial application within the meaning of PCT Art. 33(4). It can be manufactured using conventional PCB assembly, isolated power-converter topologies (flyback charger, full-bridge inverter), optoisolated signaling, and catalog thermal / mechanical components, and can be deployed at scale in standard enclosures (wall-mount, rack, or portable).

[0222] Relevant fields and typical deployments

[0223] Building services & facility management: line-interactive UPS for critical loads plus emergency-lighting back-up using the unified terminal’s lighting conductor — particularly suited to retrofits where rewiring is constrained.

[0224] Commercial / retail & security systems: PCS terminals, access control, CCTV / NVRs requiring seamless transfer and compact installation.

[0225] Telecom / IT closets & industrial controls: PLCs, network switches, small servers; 12 V / 24 V variants fit common plant batteries (VRLA, LiFePO4, Ni-Cd).

[0226] Healthcare outpatient / lab equipment (non-life-support): instrumentation needing ride-through with predictable UV cut-off behavior.

[0227] Field service, construction, and rental fleets: continuous-duty mode provides portable AC on site without simulating outages.

[0228] Disaster response / off-grid & micro-grids: chemistry-agnostic charging enables use of locally available batteries; fast, isolated protections suit harsh electrical environments.

[0229] Practical uses and advantages in operation

[0230] One device replaces three (UPS + emergency-lighting driver + portable inverter), reducing box count, wiring points, and commissioning time.

[0231] Chemistry-agnostic deployment: four independently adjustable CC / CV setpoints (charge-voltage, charge-current, charge-termination, discharge cut-off) let installers match Li-ion (e.g., NMC), LiFePO4, AGM / GEL, or Ni-Cd without firmware tools — lowering inventory and downtime.

[0232] Unified terminal interface: consolidates mains, load, and lighting signal to integrate with existing lighting branches without power-cable rerouting.

[0233] Selectable operating modes: UPS, emergency-lighting, and continuous-duty portable source via front-panel selectors expand use cases across facilities and field work.

[0234] Deterministic safety & reliability: opto-isolated line presence, UV cut-off with recovery, and CT-based over-current shutdown deliver fast hardware responses; ducted airflow with dual fans supports sustained loads.

[0235] Scalable productization: power and voltage ratings can be adapted (e.g., 12 V and 24 V classes) with the same control architecture, enabling a family of models for different markets and standards.

[0236] Accordingly, the invention offers clear commercial utility across building, industrial, telecom, and service sectors, providing lower total cost of ownership, simpler installation, and robust operation in real-world conditions.Citation ListPatent Literature

[0237] PTL1 : [PTL1] US 5,436,816 (line-interactive UPS with relay transfer)

[0238] Summary: Discloses relay-based transfer between mains and an inverter for uninterrupted supply. Designed primarily around lead-acid storage.

[0239] Relevance: Representative of classic line-interactive UPS topology and transfer behavior.

[0240] Difference / lmprovement: Unlike PTL1 , the present appliance (i) is chemistryagnostic via four independent, user-set charge parameters (CV, CC, termination, UV cut-off) and (ii) integrates an emergency-lighting signal and a continuous-duty operating mode, accessible through dual selectors and a unified terminal.

[0241] [PTL2] US 7,141,892 (line-interactive UPS; relay switching)

[0242] Summary: Uses relay switching to transfer the load between mains and inverter; teaches line-interactive behavior but is tied to a fixed battery platform.

[0243] Relevance: Establishes baseline UPS transfer concepts.

[0244] Difference / lmprovement: Present apparatus adds (a) four-parameter adjustable CC / CV charging supporting Li-ion (NMC), LiFePO4, AGM / GEL, and NiCd without firmware, and (b) a five-pin unified terminal carrying mains, load, and a lighting-control conductor — features absent from PTL2.

[0245] [PTL3] US 7,944,182 B2 (adjustable charger - current limit, fixed voltage)

[0246] Summary: Limits charge current; charge voltage is factory-fixed.

[0247] Relevance: Illustrates partial adjustability in chargers.

[0248] Difference / lmprovement: The present charger exposes four independent, field-adjustable set-points (CV, CC, termination, UVF) implemented by analog loops (TL431 + opto for CV; shunt + amplifier for CC), enabling on-site tuning across multiple chemistries — beyond the fixed-voltage approach of PTL3.

[0249] [PTL4] WO 2010 / 034079 (multi-chemistry charger using microcontroller)

[0250] Summary: Recognizes different battery profiles via microcontroller control; increases flexibility but adds cost / complexity and provides no 220 Vac output for loads.

[0251] Relevance: Example of chemistry-aware charging using digital methods.

[0252] Difference / lmprovement: The present design achieves chemistry-agnostic operation without a microcontroller, via analog CC / CV with four trimmable parameters, and further integrates an inverter with transfer and emergencylighting signaling — functionality not present in PTL4.

[0253]

[0254] [PTL5] US 4,410,835 (self-powered emergency luminaires)

[0255] Summary: Emergency lights that power an internal lamp upon mains failure;no standard AC output for general loads.

[0256] Relevance: Typical standalone emergency-lighting approach.

[0257] Difference / lmprovement: The present apparatus provides a lighting-control conductor on a unified terminal to energize an existing building lighting branch and supplies standard AC output — consolidating functions beyond PTL5.

[0258] [PTL6] US 9,107,269 B2 (emergency lights with internal battery)

[0259] Summary: Emergency luminaire systems focusing on internal illumination; output is limited to the internal lamp.

[0260] Relevance: Illustrates mainstream emergency-light design constraints.

[0261] Difference / lmprovement: Present system interfaces with building circuits via a dedicated signal and provides an AC output through relay-managed transfer and inverter — capabilities not addressed in PTL6.

[0262] [PTL7] EP 3989384 B1 (UPS optimization for data centers)

[0263] Summary: Proposes cost / reliability optimization of UPS architectures for datacenter-class loads.

[0264] Relevance: Demonstrates evolution of UPS systems toward efficiency and reliability.

[0265] Difference / lmprovement: The present appliance targets small-facility / building use and uniquely combines: a four-parameter analog charger, tri-mode operation (UPS, emergency-lighting, continuous-duty), and a unified five-pin interface — integration not taught by EP ’384.Non Patent Literature

[0266] NPL1 : [NPL1]

[0267] International Electrotechnical Commission (IEC). IEC 62040-1 : Uninterruptible power systems (UPS) — Part 1 : Safety requirements. IEC / BSI, 2019; A1 :2023.

[0268] Summary: Core safety requirements and definitions for UPS equipment (pluggable and permanently connected).

[0269] Relevance: Establishes the safety framework for line-interactive UPS appliances into which the disclosed device fits.

[0270] Contribution: Provides terminology and safety baselines relevant to enclosure, isolation, and user protection.

[0271] [NPL2]

[0272] IEC. IEC 60598-2-22: Luminaires — Part 2-22: Particular requirements — Luminaires for emergency lighting. 5th ed., 2021.

[0273] Summary: Specific performance and safety requirements for emergency luminaires and systems.

[0274] Relevance: Frames interoperability and signaling expectations for the invention’s emergency-lighting interface.

[0275] Contribution: Guides the “lighting signal” behavior and system integration constraints.

[0276] IEC Webstore

[0277] [NPL3]

[0278] Power-Sonic Corporation. Line-Interactive vs Online UPS (White Paper).Rev.1 , May 2020.

[0279] Summary: Technical comparison of UPS topologies and their operating modes.

[0280] Relevance: Supports the description and advantages of the invention’s line- interactive mode and transfer behavior.

[0281] Contribution: Supplies accepted definitions used in the specification and claims.

[0282] [NPL4]

[0283] Unitrode / Texas Instruments. A New Integrated Circuit for Current-Mode Control (Application Note U-93).

[0284] Summary: Describes current-mode PWM control, with practical shutdown / UVLO and over-current “hiccup” protection implementations.

[0285] Relevance: Corroborates the invention’s analog protection chain (UV cut-off, fast OCP) and controller interfacing.

[0286] Contribution: Engineering guidance for deterministic hardware shutdown paths used by the inverter stage.

[0287] [NPL5]

[0288] onsemi. The TL431 in the Control of Switching Power Supplies (TND381 / D).

[0289] Summary: Shows how a TL431 with an optocoupler closes precise CV loops in isolated supplies.

[0290] Relevance: Underpins the specification’s CV regulation path and adjustable charge-voltage set-point.

[0291] Contribution: Establishes industry practice for analog, isolated voltage regulation used in the charger embodiment.

[0292] [NPL6]

[0293] Renesas. Constant Current Constant Voltage (CCCV) Application for Power Adapter with LLC Output Stage. Nov. 2023.

[0294] Summary: Demonstrates CC / CV charging requirements for Li-ion, including adding a constant-current stage to CV sources.

[0295] Relevance: Supports the multi-chemistry charger’s CC / CV architecture and need for independent CC and CV loops.

[0296] Contribution: Validates design rationale for four user-set charge parameters.

[0297] [NPL7]

[0298] Battery University (Cadex). BU-409: Charging Lithium-ion; BU-409b: Charging Lithium Iron Phosphate.

[0299] Summary: Practical overviews of Li-ion and LiFePO4CC / CV charge limits, termination, and float considerations.

[0300] Relevance: Benchmarks safe voltage / current ranges and chemistry distinctions referenced in the embodiments.

[0301] Contribution: Supplies broadly recognized industry guidance for setting ch arg e / te rm i nation thresholds.

[0302] Battery University

[0303] [NPL8]

[0304] Chung, H.C., et al. “Charge and discharge profiles of repurposed LiFeP04cells,” Scientific Data (Nature), 2021.

[0305] Summary: Experimental dataset using standard CC-CV charging with defined threshold voltage and cut-off current for LiFePO4cells.

[0306] Relevance: Peer-reviewed confirmation of CC-CV practice and parameterization for LFP chemistry.

[0307] Contribution: Academic support for the invention’s chemistry-agnostic chargeparameter adjustability.

[0308] [NPL9]

[0309] Texas Instruments. An Engineer’s Guide to Current Sensing (SBAA324B), 2021.

[0310] Summary: Techniques for shunt-based current measurement and over-range detection in power systems.

[0311] Relevance: Complements the invention’s shunt-amplifier CC loop and OCP thresholding strategy.

[0312] Contribution: Design guidance for sizing sense elements and ensuring noise immunity.

[0313] [NPL10]

[0314] T riad Magnetics. CST206-1 A Current Sense T ransformer — Datasheet, Apr.2019.

[0315] Summary: Characteristics and frequency range of current-sense transformers for switch-mode applications.

[0316] Relevance: Supports the CT-based over-current sensing used to assert an isolated inverter shutdown.

[0317] Contribution: Provides component-level parameters relevant to the protection embodiment.

[0318] [NPL11]

[0319] Broadcom. Optocoupler Designer’s Guide (AV02-4387EN).

[0320] Summary: Isolation, safety, and design parameters for optocouplers in power supplies and control signaling.

[0321] Relevance: Underlies the invention’s opto-isolated line-presence detection and CV feedback paths.

[0322] Contribution: Confirms isolation practices and agency considerations for signal transfer across safety boundaries.

[0323] [NPL12]

[0324] TDK-Lambda. CUS250M Application Notes — AC FAIL / DC OK Signals, 2024.

[0325] Summary: Describes optocoupler-based AC-fail and DC-OK outputs for isolated indication of mains presence and output status.

[0326] Relevance: Mirrors the invention’s line-presence sensing concept and isolated signaling to control logic and lighting conductor.

[0327] Contribution: Industrial precedent for isolated mains-presence indication used to drive emergency-lighting mode.

[0328] [NPL13]

[0329] Pressman, A.I.; Billings, K.; Morey, T. Switching Power Supply Design, 3rd ed., McGraw-Hill, 2009.

[0330] Summary: Canonical reference on switch-mode topologies (flyback, fullbridge), magnetics, control, and protection.

[0331] Relevance: Background for the flyback charger, transformer selection, snubbers, and full-bridge inverter discussion.

[0332] Contribution: Supports enablement for practical component selection and loop compensation.

[0333] [NPL14]

[0334] Erickson, R.W.; Maksimovic, D. Fundamentals of Power Electronics, 2nd ed., Springer, 2001.

[0335] Summary: Foundational models and control of power converters, including current-mode control and averaged models.

[0336] Relevance: Theoretical grounding for the specification’s control and protection strategies.

[0337] Contribution: Academic support for the control architecture choices in the embodiments.

Claims

AMENDED CLAIMSreceived by the International Bureau on 23 May 2026 Claims1. A mains-powered emergency-lighting power unit, comprising:(a) an AC input having line (L) and neutral (N) terminals;(b) a rectifier coupled to the AC input and providing a bulk energy storage DC link; (c) a transfer stage configured to supply an AC output port having line (!_') and neutral (N') terminals from the mains in a first mode and from an inverter in a second mode;(d) a rechargeable battery interface for connecting a backup battery;(e) an analog constant-current / constant-voltage (CC / CV) battery charger circuit without any microcontroller, the charger providingfour independently adjustable parameters consisting of a charge current setpoint, a charge voltage setpoint, a charge-termination current threshold, and a discharge cut-off voltage threshold; (f) a battery undervoltage protection (UVP) circuit with hysteresis, configured to disconnect the inverter when the battery voltage falls below the discharge cut-off threshold and to re-enable the inverter only after the battery voltage recovers above a higher reconnect threshold;(g) an overcurrent protection (OCP) circuit comprising a current sensor and comparator circuitry with an opto-isolated gating element, the OCP circuit being configured to latch off the inverter when a discharge current exceeds a predetermined threshold, the inverter remaining latched off until a reset condition is detected;(h) a unified five-terminal interface comprising the input terminals (L, N), the output terminals<IMG file=null he=null id=imgf000053_0001 img-content=null img-format=null inline=null orientation=null wi=null>N ') , and an isolated lighting-control signal terminal (SIG) galvanically isolated from the mains;(i) a mains-dropout sensing detector configured to, upon detection of a mains power failure or undervoltage, (i) command the transfer stage to switch from the first mode to the second mode and (ii) assert an isolated control signal at the SIG terminal; and0) a selector assembly including a first three-position selector switch for setting an emergency lighting mode with positions OFF, EMERGENCY-ONLY, and ALWAYS-ON, and a second three-position selector switch for setting an output delivery mode with positions BYPASS, INVERTER-AUTO, and INVERTER- ALWAYS-ON.

2. The unit of claim 1, wherein the isolated lighting-control signal terminal (SIG) is coupled to the mains-dropout sensing detector via an optocoupler that provides at least 2.5 kVrms of galvanic isolation between the mains sensing circuitry and the SIG terminal.

3. The unit of claim 1, wherein the battery charger’s constant-voltage regulation loop includes a shunt reference amplifier driving an optocoupler on a primary orsecondary side of the charger’s power supply, and wherein the constant-current regulation loop includes a sensing resistor and an instrumentation amplifier, the constant-voltage and constant-current loops being configured to operate in a decoupled manner to permit independent adjustment of each of said four adjustable parameters.

4. The unit of claim 1, wherein the charge-termination current threshold is selected as a fraction of the battery’s rated capacity, and wherein attainment of the charge-termination current is detected by the constant-current regulation loop while the constant-voltage regulation loop remains in regulation.

5. The unit of claim 1, wherein the discharge cut-off voltage threshold is configurable based on the battery’s cell chemistry and wherein the undervoltage protection circuit incorporates a hysteresis of at least about 50 mV per battery cell to prevent inverter chatter or oscillation near the cut-off point.

6. The unit of claim 1, wherein the overcurrent protection circuit latches off the inverterwhen a peak discharge current exceeds a programmable threshold determined by the output of the current sensor, and wherein the latched-off state persists until the unit is power-cycled or a manual reset command is received.

7. The unit of claim 1, wherein in the ALWAYS-ON lighting mode of the first selector, the isolated lighting-control signal at the SIG terminal remains asserted regardless of the presence of mains power, thereby providing continuous illumination that automatically switches to battery power during a mains outage.

8. The unit of claim 1, further comprising a temperature-compensation circuit including a negative temperature coefficient (NTC) sensor thermally coupled to the battery or charger, the temperature-compensation circuit being configured to adjust the charge-voltage setpoint to compensate for temperature variations for at least lithium-iron phosphate (LiFePO4) and lead-acid battery chemistries.

9. The unit of claim 1, wherein the unified five-terminal interface (L, N, L', N', SIG) is implemented on a single integrated terminal block or barrier strip with labeled terminals, thereby simplifying installation and ensuring proper separation between mains-voltage wiring and the isolated signal wiring.

10. The unit of claim 1, wherein the mains-dropout sensing detector includes an AC voltage detection circuit that discriminates zero-crossings or monitors the RMS voltage level of the mains, and wherein the detector incorporates a hold-off delay of at least 50 milliseconds to filter out transient mains dips or brief disturbances so as to avoid unnecessary mode switching during short-term voltage fluctuations.AMENDED SHEET (ARTICLE 19)11. The unit of claim 1 , wherein the inverter employs a power conversion topology selected from a buck-derived topology or a flyback-derived topology to generate a regulated AC (or quasi-AC) output at the output port (!_’, N'), and wherein the output waveform provided by the inverter has a total harmonic distortion below a predetermined limit to meet power quality requirements.

12. The unit of claim 1, wherein the charger is configurable to charge batteries of either approximately 12 V nominal or 24 V nominal, and wherein corresponding recommended charge -voltage and charge-current setpoint ranges for 12 V and 24 V battery systems are indicated on the unit or defined by distinct mechanical settings or detents on the charger controls.

13. The unit of claim 1, wherein the undervoltage protection circuit and the overcurrent protection circuit share a common opto-isolated shut-down gating path to the inverter’s control input, such that a fault signal from either the UVP or OCP will disable the inverter via the same isolation interface to ensure a fail-safe shutdown under eitherfault condition.

14. The unit of claim 1, wherein the transfer stage comprises a transfer relay or an equivalent solid-state switch arrangement that performs a break-before-make transfer of the output from the mains to the inverter, the transfer stage having a switchover time of less than 20 milliseconds to maintain power continuity to the load during a mains outage.

15. The unit of claim 1, wherein the first and second three-position selector switches of the selector assembly are implemented as manual mechanical switches with fixed detented positions at each setting, thereby preventing accidental mode changes during operation or maintenance.

16. The unit of claim 1, further comprising a set of status indicator lights implemented as LEDs, including at least one LED to indicate the presence of mains power and active charging status, at least one LED to indicate the battery’s charging progress or full-charge condition, and at least one LED to indicate an undervoltage cutoff or overcurrent fault condition of the unit.

17. The unit of claim 1, wherein the isolated SIG terminal provides a low-voltage logic signal output that is capable of sourcing or sinking current into an external circuit with an input impedance of at least 10 kQ, and wherein the SIG output is protected against short-circuit conditions.

18. The unit of claim 1, wherein the charger further includes a timed safety cutoff function that terminates the charging of the battery if the battery fails to reach the charge-termination current or to stabilize at the constant-voltage setpoint within a predetermined maximum charging time interval.AMENDED SHEET (ARTICLE 19)19. The unit of claim 1, wherein the power unit is housed in a double-insulated enclosure that provides internal isolation barriers and segregated creepage / clearance distances between the mains-voltage circuits, the battery- related circuits, and the control / signal circuits, thereby complyingwith safety isolation standards for each respective domain.

20. The unit of claim 1, wherein the battery interface further comprises at least one protective device selected from a fuse, a circuit breaker, and a reverse-polarity protection element, the protective device being arranged to prevent damage to the unit in the event of an overcurrent condition or an incorrect battery connection.

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