Abstract: A generator control system of a vehicle generator includes a switching element which turns on or off field current, a field current detecting circuit, a calculating circuit which calculates an average value of the field current when the switching element turns on according to an amount of the detected field current, and a switch control circuit which cyclically controls the switching element according to the average value and a limit value of the field current.

Abstract: The present invention relates to a method and to a device for adapting the alternating current generated by a generator (1) and the alternating voltage generated by a generator (1) to a grid (8), whereby the generator (1) has at least one excitation coil (2). The power fed into the grid (8) can be flexibly adapted while entailing low switching losses in that a static frequency converter (9) is employed for the adaptation between the generator (1) and the grid (8), and in that, in order to control the power fed into the grid (8), means (3) are provided with which, on the one hand, the strength of the excitation field generated by the at least one excitation coil (2) is regulated and, on the other hand, the phase angle between the frequency converter voltage and the generator or grid voltage is appropriately controlled.

Abstract: There is provided an energy discharge apparatus for dissipating a quantity of stored magnetic energy in a generator field coil of a brushless generator. The apparatus includes an exciter regulator responsive to an output signal of the generator and which provides an exciter field signal, and an exciter field coil responsive to the exciter field signal and which provides an exciter magnetic field, and an exciter armature coil responsive to the exciter magnetic field and which provides an exciter armature signal. The apparatus further includes a control circuit responsive to the exciter armature signal, and a variable impedance in series with the generator field coil and responsive to the control circuit. The variable impedance serves to dissipate the quantity of stored magnetic energy. In another embodiment the apparatus includes a positive feedback circuit responsive to the exciter armature signal and operable to dissipate the quantity of stored magnetic energy.

Abstract: Generation of segmented sawtooth waveforms. A desired waveform is divided into intervals. A slope is associated with each interval. A charge current representing the slope is applied to a timing capacitor during each interval. Responsive to a clock signal, a counter chain indexes a digital memory which provides values to a digital to analog converter. The output of the digital to analog converter drives an adjustable current source to charge the timing capacitor.

Abstract: A control apparatus for an on-vehicle generator is provided. The generator, driven to rotate by an on-vehicle engine, is provided with stator windings, rectifiers, a field winding, and a voltage control apparatus (i.e., the control apparatus for the on-vehicle generator). The voltage control apparatus comprises a switching element (including power transistors, for example) selectably and electrically connects or disconnects a current path between the field winding and a power supply to provide the field winding with current; a storage element (for example, a battery); and a regeneration element (for example, free wheel diodes) provides the storage element with current flowing through the field winding when the switching element is turned off.

Abstract: A vehicle generating system includes a generator for a vehicle, a voltage regulator that supplies field current to the field coil at a variable duty ratio, a field current sensor that detects field current amount, a signal transmitting circuit that transmits a signal representing the detected field current amount and the duty ratio and an electronically controlling unit that receives the signal representing the detected field current amount and the duty ratio and controls the engine according to one of the detected field current amount and the duty ratio.

Abstract: The structure of the present invention includes: a switching element inserted in series in a field coil of an A.C. generator for intermittently controlling a field current supplied to the field coil in accordance with an output voltage from the A.C. generator in order to control the output voltage from the A.C. generator to a predetermined value; and conduction rate control means for detecting a rotational speed of the A.C. generator to reduce a conduction rate of the switching element in accordance with an increase in rotational speed.

Abstract: A generator apparatus can provide generated power fit for a connected battery, and even if a load voltage is not within a suitable range, when the load voltage is a certain level or more, the generator can provide power. A selector 25 selects a target voltage for controlling the output voltage of a rectifier 2. An output controller 34 controls the rectifier 2 according to the target. A load judgment section 35 judges the terminal voltage of a battery 19. When the terminal voltage is within an allowable range with respect to the target value, permission for output is given to the output controller 34. When the load voltage is not within the allowable range, an alarm is raised. Even when the alarm is raised, if a load voltage develops which is not less than a predetermined voltage lower than the allowable range, the battery 19 can be charged by forced-output.

Abstract: An alternator for a motor vehicle includes a current generation device and a rectifier. The current generation device has multiple phase stator windings in which AC currents are generated. The rectifier is connected to the windings of the current generation device. The rectifier includes multiple sets of first and second diodes for the multiple phase windings. At least one of the first and second diodes of each set is a Schottky diode. A voltage clamping device is connected to the rectifier to protect the Schottky diodes from surge reverse voltage.

Abstract: A permanent magnet starter/generator subsystem configured in a fault tolerant architecture is described herein for small engine applications. The system allows for lighter system weight, improved system reliability, higher performance capability and reduced maintenance.

Abstract: A generator control circuit is disclosed that includes a first circuit (40) monitoring a generator voltage and producing a first output when the voltage is below a first level, a second circuit (48) monitoring a generator current change rate and producing a second output when the current change rate is above a second level, and a third circuit (13, 28) operatively connected to the first circuit (40) and the second circuit (48) for decreasing a power level supplied to the generator when a plurality of conditions are satisfied, the plurality of conditions including the voltage being below the first level and the current change rate being above the second level. A method of controlling a generator is also disclosed.

Abstract: A DF signal averaging circuit includes a counter for counting a clock signal fed from a clock signal generator, an OR circuit which causes the counter to perform count-up operation only when a transistor is in an ON state with the clock signal and a potential signal fed from the clock signal generator and a positive electrode of the transistor, respectively, a memory circuit for calculating an averaged DF signal from output values of the counter with specific timing, and a preset control circuit for calculating a preset value for the counter from the averaged DF signal fed from the memory circuit and setting the preset value in the counter with specific timing. The averaged DF signal output from the memory circuit is transmitted to an external control unit which is an ECU of a vehicle via a communication interface.

Abstract: An active damping arrangement for a power conditioning circuit comprising a converter or an inverter and an electronically driven output line having an output terminal for connecting to an external load, the active damping arrangement comprising an inductor-capacitor low-pass output filter (OPF) for connecting between an output of the inverter/converter (PWMVC or BBHCC) and the output terminal; means for sensing current in or voltage across the capacitor or voltage between one end of the capacitor (C) and an effective neutral point; means for multiplying the sensed voltage or current by a coefficient G to provide a damping signal, and means for feeding back the damping signal to an input of the inverter/converter (PWMVC or BBHCC), thereby to damp the output of the inverter/converter.

Abstract: Systems, methods and devices are described for controlling a vehicle electrical generator. A regulator for controlling a generator in response to an input signal received from a control module suitably includes a discriminator module, a processing module and a switching circuit. The discriminator determines whether the regulator is operating in voltage or torque control mode. If the input signal is a voltage control, the output generator produces a modulation signal to produce a desired voltage between two battery terminals. If the input signal is a torque control, the output generator produces one or more modulation signals (e.g. pulse width modulation signals) to control the torque of the generator. The modulation signals are applied across a field coil or other controllable element of the generator by a switching circuit that applies positive and/or negative voltage from the battery terminals as appropriate.

Abstract: A generator controller (4) is provided which is able to detect and respond to failure of a generator output voltage sensor, whilst being able to distinguish voltage sensor failure from output voltage collapse due to the presence of an overload or short circuit condition. The presence of a voltage sensor failure is indicated by the measured output voltage being below a first voltage threshold whilst the output current is also below a current threshold.

Abstract: An IC regulator for controlling an alternator by changing contents of control in dependence on ambient temperature includes a control voltage limiter (2), a field current controller (3), a temperature sensor (4), a first comparator (5) for comparing the ambient temperature (T) with an activation temperature (TP1) and a reset temperature (TS1), and a second comparator (6) for comparing the ambient temperature (T) with a second activation temperature (TP2). The first comparator (5) outputs a limiter control signal (C2) when the ambient temperature (T) exceeds the first activation temperature (TP1) while resetting the limiter control when the temperature (T) becomes lower than the first reset temperature (TS1). The second comparator (6) outputs a field current interrupt signal (C3) when the ambient temperature (T) exceeds a second activation temperature (TP2) while resetting the signal (C3) when the temperature (T) becomes lower than the second activation temperature (TP2).

Abstract: A vehicular alternator failure determination apparatus is capable of making a failure determination accurately. The apparatus includes a maximum voltage detection part (1) for detecting a maximum voltage of an alternator commutating device which commutates an AC output of the alternator driven by an engine, a minimum voltage detection part (2) for detecting a minimum voltage of the alternator commutating device, a voltage difference calculation part (3) for detecting a difference voltage from outputs of the maximum and minimum voltage detection parts, and a failure determination part (4) which determines that the alternator is in a failure state, when an output of the voltage difference calculation part is equal to or greater than a prescribed voltage.

Abstract: An electronic control apparatus includes target FR calculator that calculates a target exciting current duty ratio FR based on an exciting current inputted from FR terminal of a regulator and flowing through field coil, and information of engine operating conditions. The electronic control apparatus also includes target FR limit value FRCLP calculator that calculates a FRCLP corresponding to a drive torque limit value based on an output of a correlative information detector. A comparator compares target FR and FRCLP, outputs a control signal within FRCLP to a control unit, and controls a duty ratio FR of exciting current flowing through a field coil not to be larger than FRCLP.

Abstract: An electro-mechanical energy conversion system coupled between an energy source and an energy load including an energy converter device having a doubly fed induction machine coupled between the energy source and the energy load to convert the energy from the energy source and to transfer the converted energy to the energy load and an energy transfer multiplexer coupled to the energy converter device to control the flow of power or energy through the doubly fed induction machine.

Abstract: A method and apparatus of stator voltage control for an induction generator. Each phase of the induction generator stator is connected through a secondary coil of a transformer to a utility grid. A stator voltage control circuit is connected in parallel with a primary coil of the transformer. The stator voltage control circuit consists of an on/off switch device connected to a full wave rectifier comprised of four silicon diodes. A single pulse width modulation (PWM) control is utilized to control the on/off switch devices of each phase of the induction generator stator.

Abstract: Method and system are provided for operating a generator using a dynamic capability curve. In one embodiment, the method allows providing a family of static capability curves corresponding to nominal reference levels of pressure of a fluid for cooling the generator. The method further allows acquiring data indicative of the actual pressure of the cooling fluid. A dynamic capability curve is generated to be responsive to the actual pressure of the cooling fluid. The family of static capability curves may be displayed relative to the dynamic capability curve, thereby allowing the operator to monitor and control the operation of the generator based on the actual pressure of the cooling fluid and further in view of at least one of the nominal reference levels of pressure for the cooling fluid.

Abstract: A generating set includes an engie driven generator (PGM) having two sets of stator windings (Ga and Gb). A bi-directional AC/DC converter (BCo) has its AC input connected to a junction between the two sets of stator windings (Ga and Gb) and its DC input connected to a number of the generator (PGM) is converted into an intermediate DC link by a convertor (Col) to produce an output for a load Lo. In normal operation of the system, an emf generated in one (Ga) of the sets of stator windings is rectified by the bi-direcitonal converter (BCo) to charge the energy storages (ESI-ESN) whilst the remainder of the generator output is fed through the converter to the load (Lo). In the event of a stepped increase in the load demand, the bi-directional converter (BCo) is operated to feed energy from the storage devices (ESI-ESN) to the stator windings (Ga) of the generator (PGM) to impart a driving torque to the generator rotor to accelerte the rotor to meet the increased load demand.

Abstract: A reference voltage of an output terminal of a synchronous machine is set according to a reactive current output from the synchronous machine, a reference voltage of the high voltage side of a transformer, and a phase compensation transfer function to quicken attenuation of an electric power fluctuation.

Abstract: A vehicle power generation control apparatus that has a power supply circuit, a rotation detecting circuit, an exciting current detecting circuit, an exciting current control circuit, a torque detecting/maximum exciting current determining circuit and a power transistor. When a speed of rotation of a vehicle generator is detected by the rotation detecting circuit and an exciting current flowing through an exciting winding of the vehicle generator is detected by the exciting current detecting circuit, the torque detecting/maximum exciting current determining circuit calculates an upper limit value of the exciting current so that a rate of change of a generator torque does not exceed a predetermined value, and the exciting current control circuit controls the exciting current so that the exciting current becomes below the limit value. This can prevent the engine revolution from becoming unstable due to variation of load or variation of engine revolution.

Abstract: A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

Abstract: An excessive voltage protection system for a variable frequency generating system detects single point failures in a generator control unit and prevents excessive voltages at a point of regulation (POR) in the system. The generator control unit is designed to detect failures, such as a loss of three-phase sensing capability, switch failure in the exciter drive circuit, and/or exciter current loop failure. If a failure occurs, the generator control unit stops operation of the exciter drive circuit, preventing the voltage at the POR from rising to undesirable levels.

Abstract: An automotive alternator is provided which includes a rectifier, a circulating circuit, and a controller. The circulating circuit is connected in parallel to a field winding to circulate the field current in the event that supply of the field current to a field winding is cut. The circulating circuit consists of a first circuit formed by a diode and a second circuit working to enhance attenuation of the field current. The controller works to select the second circuit when a voltage of the output of the rectifier exceeds a reference value and select the first circuit when the voltage of the output of the rectifier is less than the reference value.

Abstract: In an alternator, failure in a power supply line connected to an output terminal of a rectifier is detected. Upon detection of a failure in this power supply line, power generation is suppressed for a predetermined period that is longer than the time constant of a field winding of the alternator. Preferably, a high voltage pulse is detected to discriminate a first condition where a single high voltage pulse is generated when an electrical load connected to the power supply line is cut off and a second condition where a high voltage pulse is repeatedly and frequently generated when a failure occurs in the power supply line. Only when the second condition is discriminated, power generation suppression control of the alternator is conducted.

Abstract: A voltage regulator for an a.c. generator produces a power generation ratio signal having a duty ratio corresponding to the current supply to the field winding of the a.c. generator. This power generation ratio signal is applied to an external apparatus through a signal wire. The duty ratio of the power generation ratio signal is more than 10% when the a.c. generator is normal. When abnormality is detected, the power generation ratio signal is partly masked by an abnormality detection signal so that the duty ratio of the power generation signal is reduced to be less than 10% and this change may be detected by the external apparatus. Alternatively, the power generation ratio signal may be transmitted only intermittently when the abnormality is detected.

Abstract: The system is directed to preserving an IC engine installation from potential overload and failure in response to electrical load increases passed along by an associated engine driven digitally controlled starter/alternator. The system controller monitors starter/alternator output and phase current and/or regulates the rate of change of output current in response to increasing electrical load. In an instance where monitored rates of output current change exceed predetermined thresholds, the response rate of the starter/alternator, i.e., rate of change of output current, is set at a predetermined threshold so as to prevent the braking effect of the increasing electrical load from stalling the I.C. engine or causing other operational failure.

Abstract: A voltage regulator is part of a vehicle charging system having an alternator or generator and field winding and connected to a vehicle battery and devices for supplying a voltage and powering vehicle devices. The voltage regulator includes a microcontroller operative for monitoring output voltages representative of monitored load changes within the vehicle. A power output circuit is operatively connected to the microcontroller and connects to a field winding. The microcontroller is operative for changing the field duty cycle of the generator or alternator by turning ON and OFF the power output circuit in a predetermined manner as established by the microcontroller based on monitored load changes.

Abstract: A flywheel energy storage device, for producing electrical power in an allowable range of operating voltages for an output load, includes an energy storage flywheel supported for rotation on a bearing system, and a brushless motor and a brushless permanent magnet generator for accelerating and decelerating the flywheel for storing and retrieving energy. The generator has a multiplicity of windings for producing output power from the generator by a magnetic coupling that provides output power DC voltage. An out regulator circuit provides variable DC voltage that is maintained within the allowable range for connected loads as the flywheel slows during discharging. The output regulator circuit includes electronic switches for switching connections of the windings to change the number of windings connected to the output to maintain output power DC voltage within the allowable range. The switching occurs less than once per every 10 revolutions of the flywheel.

Abstract: A generator control system for a vehicle includes an AC generator, a switch connected in series with a field coil, a voltage regulator unit, a field-current restricting unit for controlling the switch to turn on or off, a forbidding unit having a command signal input terminal for forbidding operation of the field-current restricting unit when a voltage higher than a predetermined regulation voltage is applied to the command signal input terminal.

Abstract: A vehicular power generation control device has a voltage control circuit, a power supply circuit and a power control circuit. The voltage control circuit controls the field current of a power generator by turning on and off a transistor. The power control circuit has an ignition switch closure detection circuit and an engine rotation detection circuit. When a closure of the ignition switch is detected by the ignition switch closure detection circuit, an operation of the rotation detection circuit is stopped. When the closure is not detected, the operation of the rotation detection circuit is started.

Abstract: An apparatus and method are provided to deliver a pair of output signals indicative of engine rotational speed and/or generator rotational speed. The signals are compared to each in order to determine if a generator is operating properly. At least one output signal is delivered to, or developed internally and used by, a voltage regulator of the generator. One output signal is generated based on a ripple on a positive voltage input to the voltage regulator from a generator. The other signal is indicative of the voltage at the rectifier bridge.

Abstract: The method for regulating a generator including three stator windings (U, V, W) and a converter bridge (11) including controllable switch elements (15 to 20) includes temporarily connecting the stator windings (U, V, W) in an otherwise currentless time interval with a charge source (21) that supplies an additional charging current to the stator windings (U, V, W) in addition to induced current present in the stator windings (U, V, W). The additional charging current provides the generator (10) with additional magnetic energy. In a preferred embodiment of the method, the supply of additional charging current to the stator windings is controlled by a logistics element (27) for setting a turn-on time and a longest on-time duration of at least one switch element and a comparator (25) that produces a comparison output according to a comparing of an actual current value with a predetermined maximum value.

Abstract: The invention relates to a generator system for a motor vehicle, which comprises an asynchronous generator and a converter. The converter serves for the production of converter output voltages from a direct current source, which form a three-phase system which, inside the machine, produce a rotating field suitable for the generator function for the formation of rotating fields suitable for the generator function. The converter output voltages thereby have a frequency—referred to in the following as a CO frequency—which is changeable in dependence on the range of rotational speed of the generator. The voltage curve of the converter output voltages can be broken down into a primary component with a sinusoidal voltage curve of the CO frequency and into at least one additional secondary component with a sinusoidal voltage curve with an odd-numbered multiple of the CO frequency.

Abstract: Method and apparatus for changing the rating of engine generator set by selecting a generator set rating using a rating selector included in the generator set control system. The generator set rating includes at least an engine rating and voltage.

Abstract: An output stage of a conventional Frequency-on-Demand electronic voltage regulator, such as a voltage regulator of the type described in U.S. Pat. No. 5,642,033, is reconfigured as a bi-stable multivibrator, or flip-flop. An oscillator provides a reset pulse of pre-defined pulse width and pulse period to initiate an “on” period of the output stage; a conventional error amplifier synchronously switches the output stage “off” when a system voltage reaches a preset value. Voltage regulation by a constant-frequency, pulse-width-modulated, output signal is thus realized at reduced cost and complexity. Total capacitance between the gate-source terminals of a preferred MOS power output transistor serves to slow both negative- and positive-going output control signal transitions, introducing a minimum of electrical noise into the vehicle's electrical system.

Abstract: Among the embodiments of the present invention is an apparatus that includes an alternator field coil, a driver coupled to the alternator field coil to provide excitation current thereto, and a recirculation circuit coupled to the alternator field coil. The recirculation circuit includes a unidirectional current device and a current sensing device electrically coupled in series. The driver is electrically coupled between a first electrical power supply node and the field coil, and the recirculation circuit is electrically coupled between the driver and a second electrical power supply node.

Abstract: A voltage regulator of a vehicle AC generator includes a control circuit connected to a power circuit for supplying field current to a field coil of the AC generator, a power circuit for supplying electric power to the control circuit, a power drive circuit for controlling the power circuit according to a self-excited voltage induced in an armature coil of the AC generator, and a bypass circuit connected to a ground. The resistance of the bypass circuit is reduced when the power circuit does not supply electric power to the control circuit and is increased when the power circuit supplies electric power to the control circuit. Therefore, power consumption of the bypass circuit is reduced when the AC generator starts regular power generation.

Abstract: An alternator/inverter system for use with a portable generator which includes a voltage regulation system. The alternator/inverter incorporates a pair of permanent magnet generators (PMGs), a pair of active rectifier circuits, a pair of DC bus capacitors and a pair of H-bridge inverters, forming two distinct alternator/inverter sections. Each alternator/inverter section provides a 120 VAC output, and a 240 VAC output is formed between the two alternator/inverters sections. The voltage regulation system is formed from a pair of voltage regulation circuits that are associated with each alternator/inverter section. The circuits monitor the DC bus voltage of each alternator/inverter and determine the DC losses resulting from electrical cabling coupling the alternator/inverters to external loads, as well as the H-bridge inverters.

Abstract: A circuit configuration for controlling the field current of an alternating current generator in a vehicle electrical generator system includes a digital to analog converter for converting a digital command signal to an analog voltage. A first comparator compares the system field current with the converted analog voltage. A switched component, operatively connected to a power switch, is switchable in response to the comparator output. A frequency generator, operatively connected to the switched component, provides timed pulses to periodically tell the switched component to turn on the power switch.

Abstract: The present control circuit and method extends the operating range of digitally sampled control loops. A programmable output of a generator is controlled. The programmable output includes a an output level having a corresponding set point. The generator has a drive input that is driven to an actual drive point for controlling the output level of the programmable output. A set point corresponding to a requested output level is determined. A predicted drive point is then determined. The actual drive point of the generator drive input is forced to the predicted drive point. The output level of the programmable output is sensed. A digital output signal that is representative of the sensed output level is generated. The actual drive point of the generator drive input is controlled based on the digital output signal, such that the output level of the programmable output is controlled. The actual drive point corresponding to the requested output level is then stored.

Abstract: The present invention features a voltage-limiting regulator for use with an AC generator having DC-excited fields. The AC output voltage from the generator is sensed and compared to a fixed reference representative of the sensed difference is amplified and applied to the DC field excitation input of the AC generator. As the DC voltage supplied to the field varies, the AC output voltage from the generator may be held constant under varying load conditions. The voltage-limiting regulator is particularly useful for vehicle-mounted, high power, single phase AC generators.

Abstract: An automatic voltage-regulating system for an engine generator includes an output voltage detecting device for extracting a single-phase AC output voltage from an output winding wound around a stator to output a detection voltage, and a switching device for regularizing the output voltage to be substantially at a constant level by selectively conducting and cutting off of a field current supplied from an exciting winding wound around the stator to a field winding wound around a rotor. Depending upon whether the detection voltage is higher or lower than a predetermined value, the charged voltage of a condenser for smoothing a rectified output from the field winding is divided by a pair of voltage dividing resistors. A switch device is forcibly turned on by a detection voltage in response to the voltage at a connection point between the pair of resistors exceeding a predetermined voltage value, to thereby cause the smoothing condenser to be discharged.

Abstract: A method is provided for regulating a three-phase machine functioning under any operational conditions without a mechanical rotary transducer. The machine is supplied with D.C. power by an inverter, where parameters of a D.C. link using an actual switching state of the inverter are detected for regulation. The method includes measuring (1) flow direction required for field-oriented control in asynchronous machines, and (2) rotor position for rotor-oriented control in synchronous machines. The measuring is performed by using spatial magnetic conductivity fluctuations in the machine. The conductivity fluctuations are detected using parameters for a D.C. link. An actual switching state of an inverter is used in the measuring process. Mathematical evaluation to calculate flow direction or rotor direction is then performed.

Abstract: Shift means shifts a rotation speed range to a low rotation speed side based on an electricity amount related to rotation speed. In the rotation speed range, driving torque of a generator is suddenly changes as a result of an increase of duty ratio of a switch due to a shortage of generation capacity caused by a reduction of a rotation speed of a vehicle alternator. Preferably, the shift means shifts the rotation speed range to the low rotation speed side by changing the adjust voltage based on the electricity amount related to rotation speed while the rotation speed is reduced.

Abstract: Devices and methods for controlling a generator with an associated voltage converter that functions as a step-up converter are disclosed, in which the control of the generator is done as a function of its rpm and/or as a function of the rpm-dependent possible output voltage of the generator. Three different ranges are defined, in each of which different control actions are performed: at low rpm, a power control at the maximum allowable exciter current; at higher rpm levels, a voltage control by influencing the exciter current; and at an overvoltage at higher rpm and a sudden load reduction, a third control strategy, which reduces the overvoltage and the exciter current.

Abstract: An abnormality detection apparatus for a power supply circuit associated with an internal combustion engine detects an abnormality that may occur in a power supply circuit, and controls the automatic stop and the automatic start of the engine based on the state of the power supply circuit. The state of charge/discharge of a battery determined based on the electric potential of a terminal located between the battery and a generator-motor or a load is compared with the current through the battery detected by an ammeter. If there is a contradiction therebetween, it is determined that an abnormality has occurred somewhere in the power supply circuit including the battery. When it is determined that the power supply circuit has an abnormality, the apparatus performs such a control as to prevent the automatic stop/start control in which the engine is automatically stopped if a predetermined condition is met, and in which the engine is automatically restarted when the condition is unmet after being met.