A rotary electric machine for a vehicle that is capable of starting synchronous rectification through switching elements after having ensured absence of a short circuit fault. The rotary electric machine includes a multi-phase armature winding, a switching element set that includes a plurality of pairs of upper-arm and lower-arm switching elements to form a bridge rectification circuit together with the armature winding, an on/off-timing setter that sets on/off-timing of each switching element, a switching element driver that drives each switching element at the on/off-timing set by the on/off-timing setter; and a synchronous control start determiner that determines timing when an energization period for the upper-arm switching element and an energization period for the lower-arm switching element occur alternately as start timing of the synchronous rectification.

An electrical generator includes a stator having fractional-slot concentrated windings and a rotor having field windings. A drive is provided having a circuit to control current flow to the field windings and a controller to input an initial DC field current demand to the circuit to cause the circuit to output an initial DC field current representative of a DC field current demand that would cause an electrical generator having sinusoidal stator windings to output a desired AC power. The controller receives feedback on the magnetic field generated by the initial DC field current, isolates an ideal fundamental component of the magnetic field based on the feedback and to generate a modified DC field current demand, and inputs the modified DC field current demand to the circuit, thereby causing the circuit to output an instantaneous non-sinusoidal current to the field windings to generate a sinusoidal rotating air gap magnetic field.

A wind power generator generates power through a rotation of a rotor and is interconnected, and operated with its power generation output previously limited in order to be able to further supply the power to a power system in response to a decrease in system frequency. Thus, a concentrated control system derives a required restricted amount corresponding to a power generation output required to respond to the decrease in system frequency, derives a value by subtracting an amount corresponding to a latent power generation output with which the power generation output can be increased, from the required restricted amount, and sets a restricted amount of the power generation output in each wind power generator to perform the operation with the power generation output previously limited to respond to the decrease in system frequency, based on the above value.

The present invention provides a method and a device for primary frequency regulation based on bang-bang control, the method comprises: obtaining in real-time a power grid frequency of a steam turbine generator set; performing a subtraction operation on a rated power grid frequency and said power grid frequency to generate a power grid frequency difference; performing a dead zone process on the power grid frequency difference according to a dead zone fixed value to generate a frequency difference; performing a frequency difference compensation operation on the frequency difference to generate a frequency difference compensation instruction; and combining an original primary frequency regulation output instruction with the frequency difference compensation instruction and outputting the result to a steam turbine speed regulation system when a selecting switch is 1.

A fault tolerant electrical machine including: a plurality of phases; a detector arranged to detect a fault in at least one of the phases; and a controller arranged to intentionally cause a fault in at least one other of the phases such that the vector sum of the second harmonic power vectors of the remaining phases is zero.

A generator system includes a generator having a stationary portion and a rotating portion. The generator includes a permanent magnet based exciter with permanent magnets disposed on the stationary portion. A first channel includes a first main field winding and a first main field power converter disposed on a rotating portion. The first main field power converter selectively delivers voltage from the exciter winding to the first main field winding. A second channel includes a second main field winding and a second main field power converter disposed on the rotating portion. The second main field power converter selectively delivers voltage from the exciter winding to the second main field winding. A generator control unit is connected to the first channel and the second channel. The generator control unit monitors an output voltage at each of the first channel and the second channel and generates the first and second control signals based on the output voltage.

A generator airgap monitoring system includes a first proximity sensor disposed in a first location of a stator and configured to transmit a first signal representative of a first distance between the first proximity sensor and a plurality of rotor poles of a rotor, and a controller communicatively coupled to the first proximity sensor. The controller is configured to derive a first plurality of instantaneous airgaps based on the first signal and to determine a difference between a first instantaneous airgap of the first plurality of instantaneous airgaps and a second instantaneous airgap of the first plurality of instantaneous airgaps. The first plurality of instantaneous airgaps includes a first plurality of measurements of airgaps between the stator and the plurality of rotor poles when the rotor is rotating. The first instantaneous airgap and the second instantaneous airgaps include measurements for respective rotor poles.

An inverter generator used in combination with a motor and an ECU generating a pulse at each predetermined rotation angle of the motor is comprised of: an electric generator driven by the motor configured to generate alternating current electric power; estimating means for estimating an electrical angle of alternating voltage of the alternating current electric power from the pulse, the estimating means being electrically connected with the ECU; a converter configured to convert the alternating current electric power into direct current electric power, the converter electrically connected with the electric generator and the estimating means; and an inverter configured to convert the direct current electric power into alternating current output electric power, the inverter electrically connected with the converter.

A wind energy plant comprising a rotor having blades and a generator driven by said rotor for generating electric energy. The pitch of the blades can be adjusted and a pitch system for adjusting the pitch angle of the blades is provided, which is supplied by a hub power source. An additional electric load is provided on the hub. A pitch power control device is provided which dynamically distributes the power of the hub power source between the pitch system and the additional electric load and further acts on the pitch system such that its power consumption during high-load operation is reduced. Thus, the power consumption of the pitch system during high-load operation can be reduced and additional power provided for operating the additional load. Even large additional loads, such as a blade heater, can be operated in this way, without having to boost the hub power source.

The control system of this floating wind turbine generator is a control system of a floating wind turbine generator in which the control system controls a pitch angle control section by a pitch angle instruction value calculated on the basis of signals detected by a second sensor detecting a relative angle between a nacelle and a tower and a third sensor detecting a yaw angle from a reference position of the tower so that a signal detected by a first sensor detecting wind direction deviation relative to a vertical direction of a rotation plane of wind turbine blades indicates an angle within a predetermined range from the vertical direction of the rotation plane of the wind turbine blades, and controls a yaw driving device by a yaw driving instruction value calculated on the basis of the signals detected by the second sensor and the third sensor.

A DC chopper comprising a control unit and a power circuit and a DC chopping method for a DFIG (doubly fed induction generator) system are provided. The input terminal of the control unit is coupled to a DC capacitor of a converter to detect a DC voltage. The power circuit includes input terminals, an overvoltage protection module, a rectifier module and output terminals. The overvoltage protection module comprises at least one discharge unit formed from a discharge resistor and a switch element, and the rectifier module is coupled in parallel to the overvoltage protection module. When a grid voltage drops, the control unit outputs a corresponding control signal to drive the switch element to be ON or OFF, and the output terminal of the power circuit absorbs a portion of rotor inrush current, so as to impose over-current protection.

An electric power generation system (EPGS) employs both a wild-source generator and a variable and/or constant frequency generator. The wild-source generator is coupled to receive mechanical power from a low-pressure spool on an aircraft engine and to generate in response a wild-source output for consumption by voltage and frequency-tolerant loads. The variable and/or constant frequency generator is coupled to receive mechanical power from a high-pressure spool on the aircraft engine and to generate in response a variable and/or constant frequency output for consumption by voltage and frequency-intolerant loads.

An alternator has rectifying module groups. The rectifying module groups form a bridge circuit. The rectifying module groups have a load dump protection judgment section for monitoring an output voltage of rectifying module groups. When the monitored output voltage exceeds a first threshold voltage, the load dump protection judgment section provides to a control section an instruction to turn on MOS transistors in a lower arm of the bridge circuit at a time when a predetermined delay time has elapsed. When a second threshold voltage is lower than the first threshold voltage and the monitored output voltage becomes less than the second threshold voltage after the monitored output voltage exceeds the first threshold voltage, the load dump protection judgment section provides to the control circuit an instruction to turn on the MOS transistors in the lower arm after the MOS transistors are turned off during a predetermined time length.

An integrated power system suitable for simultaneously powering marine propulsion and service loads. The system includes: (a) at least one generator configured with at least first and second armature windings configured to output respective first and second alternating current power signals of different voltages, the at least two armature windings positioned within the same stator slots so that they magnetically couple; (b) at least first and second rectifier circuits coupled to said generator to convert said first and second alternating current power signals into first and second direct current power signals; and (c) a first load to which said first direct current power signal is coupled and a second load to which said second direct current power signal is coupled.

An electrical machine includes a stator having a main armature winding, an exciter field winding, and a transformer primary winding. A rotor is operatively connected to rotate relative to the stator, wherein the rotor includes an exciter armature winding operatively connected to the exciter armature winding for field excitation therebetween, a main field winding operatively connected to the main armature winding for field excitation therebetween, and a transformer secondary winding operatively connected to the transformer primary winding to form a rotating transformer. A generator control unit is operatively connected to the main armature winding, exciter field winding, and transformer primary winding to control the main armature and exciter field windings based on excitation in the primary winding received from the transformer secondary winding.

An on-demand electric power system for providing on-demand electric power in remote locations. The on-demand electric power system generally includes a protective housing, an engine-generator within the protective housing, a control switch electrically positioned between the engine-generator and an electric load, and a control unit in communication with the engine-generator and the control switch to control operation of the engine-generator along with electrical power to the electric load. The control unit detects when electrical power is required by an electric load and then first starts the engine-generator. After a period of time, the control unit then closes the control switch to provide electrical power to the electric load.

A method for converting heat to electric energy is described which involves thermally cycling an electrically polarizable material sandwiched between electrodes. The material is heated by extracting thermal energy from a gas to condense the gas into a liquid and transferring the thermal energy to the electrically polarizable material. An apparatus is also described which includes an electrically polarizable material sandwiched between electrodes and a heat exchanger for heating the material in thermal communication with a heat source, wherein the heat source is a condenser. An apparatus is also described which comprises a chamber, one or more conduits inside the chamber for conveying a cooling fluid and an electrically polarizable material sandwiched between electrodes on an outer surface of the conduit. A gas introduced into the chamber condenses on the conduits and thermal energy is thereby transferred from the gas to the electrically polarizable material.

This invention is directed to a system that generates a sufficient level of electricity through access to a municipal water supply line to run a furnace during below freezing temperatures. The system includes an inlet that draws water from a water supply line. A first conduit, in communication with the inlet, transports the water into a DC generator that includes an impeller to generate electricity. Water is then routed through a second conduit which then returns the water to the water supply line through an outlet. A solenoid valve may be positioned between the inlet and first conduit which remains closed when the electric grid runs normally but will open during a power outage to supply water to the DC generator. A lithium battery stores power created by the DC generator, which may include a voltage regulator and inverter to convert to DC.

A magnetic controlled power generator provides a magnetic controlled loading device, power generator and flywheel device to form two independent modules which are easily assembled and disassembled for easy manufacture and maintenance. Besides, the magnetic controlled power generator has simple installation and lightweight components to generate a radial displacement for magnetic flux control, achieving continuous adjustment of the load resistance, thereby having the effect of reducing the cost and weight.

Some embodiments relate to a method of controlling speed of a variable speed generator. The method includes detecting a load of the variable speed generator and determining a target speed for the variable speed generator based on the load supplied by the variable speed generator. The method further includes using a controller to adjust the speed of the variable speed generator based on the target speed. The method may further include correcting the target speed by calculating a correction factor that corrects the target speed based on a voltage produced by the variable speed generator.

A dip in the output voltage of a motor-vehicle alternator, owing to a connecting of a load or a change in speed, is compensated with the aid of an alternator regulator which provides a control signal that has a duty factor and increases the excitation current of the motor-vehicle alternator. After the occurrence of the voltage dip, in a first step, the duty factor of the control signal is increased by a differential amount, and in a subsequent second step, the rate of correction is limited. After the occurrence of the voltage dip, parameters describing the instantaneous working point of the motor-vehicle alternator are determined, and in the first step, the differential amount is set as a function of the working point.

A self-excited alternator for generating electrical energy. The alternator includes a stator, a rotor, and an exciter. The rotor includes conductors which are integrated within the rotor via one of a casting process, a welding process, or a fastening process. The exciter includes a magnet producing a static magnetic field, and a rotatable conductive member coupled to the shaft and electrically coupled to the one or more conductors. The rotatable conductive member is operable to output the direct current to the one or more conductors upon rotation within the static magnetic field, thus exciting the alternator.

Systems and methods for monitoring excitation of a generator based on a faulty status of a generator breaker are provided. According to one embodiment, a system may include a controller and a processor communicatively coupled to the controller. The processor may be configured to receive, from a contact associated with a generator breaker, a reported status of the generator breaker, receive operational data associated with one or more parameters of a generator associated with the generator breaker, and correlate the reported status of the generator breaker and the operational data. Based on the correlation, the processor may establish an actual status of the generator breaker, and, based on the actual status, selectively modify a mode of excitation of the generator.

A temperature detection device that detects a temperature of a rotor of a motor. The temperature detection device has a current detection unit configured to detect a current value of a current flowing through a winding with which any one of a stator and the rotor of the motor is provided, an iron loss estimation unit configured to estimate an iron loss of the rotor using the current value, and a rotor temperature estimation unit configured to estimate the temperature of the rotor using the iron loss.

According to an embodiment, a method of operating a wind turbine comprising a DC-to-AC voltage converter is provided, the wind turbine being connectable to a grid via the DC-to-AC voltage converter, the method comprising: determining a line voltage of a power line connecting the DC-to-AC voltage converter to the grid; if the determined line voltage exceeds a predefined voltage threshold value, injecting reactive current into the power line, wherein the amount of reactive current injected is chosen such that an output voltage of the DC-to-AC voltage converter is kept within a predetermined voltage range.

A generator includes a permanent magnet generator, an exciter and a main generator mounted for rotation on a shaft. The main generator is configured to produce a voltage output. A generator control unit includes a circuit configured to provide current from the permanent magnet generator to the exciter. A switch is provided in the circuit and is configured to change between open and closed conditions. The switch is configured to flow current in the circuit in the closed condition and interrupt current flow in the open condition. An overvoltage limit controller is programmed to determine an amount of overvoltage of the output voltage exceeding a desired voltage. Either a fixed reference threshold is used or a reference threshold voltage is calculated based upon the duration in over voltage condition, and the switch is modulated between the open and closed conditions according to error between the actual output voltage and the reference threshold voltage to limit the output voltage to the desired reference threshold voltage.

A generator system includes a generator having a stationary portion and a rotating portion. An exciter field winding and a main armature winding are disposed on the stationary portion. An exciter armature winding and a main field winding are disposed on the rotating portion. A frequency demodulator is configured to extract a frequency modulated control signal from the exciter armature winding and to demodulate the frequency modulated control signal to generate a demodulated control signal. The generator includes a main field rotating power converter to selectively control current in the main field winding in response to the demodulated command signal. The generator system includes a generator control unit in electrical communication with the generator to monitor the output voltage at the main armature winding and to output an exciter current including the frequency modulated control signal to the exciter field winding based on the output voltage.

A DC motor assembly (10) with soft starting capability is provided. The assembly (10) comprises a DC motor (12) including an armature (14) and a field winding (16) adapted to be excited separately from the armature; and circuitry configured to controllably increase current flow through the field winding of the DC motor as a function of time during starting of the DC motor.

A method of controlling a generator (110) of an electric drive (104) associated with an engine (102) is provided. The method may determine an operational state of the electric drive (104) based on a speed of the engine (102), and selectively engage one of a map-lookup control scheme (150) and a fixed-theta off control scheme (152) for operating the generator (110) based on the operational state of the electric drive (104).

A system configured for charging and distribution control is provided. The system includes a switching regulator, a control circuit and a first converter. The switching regulator is configured to be selectively operable in one of a first operative state and a second operative state based on a control signal. The first operative state and the second operative state are associated with a maximum level of an alternator output power corresponding to at least one alternator operational feature, at least one alternator operational feature being associated with the alternator output voltage and an alternator speed. The control circuit is configured to generate the control signal based at least on the at least one alternator operational feature. The first converter is configured to generate a first converter output voltage based on the regulated DC output voltage. The first converter output voltage is lower than the regulated DC output voltage.

A power supply system for a motor vehicle includes a generator that includes a rotor having a field coil and a stator having an armature coil; a rectifier that rectifies AC power generated in the armature coil; an excitation control circuit that takes control of a voltage applied to the field coil; a capacitor that is connected to the DC side of the rectifier, and receives and transfers the rectified power; a battery connected to an electric load of the motor vehicle; a DC-DC converter that is connected between the capacitor and the battery and capable of converting unidirectionally or bidirectionally an input DC voltage into any DC voltage; and a selection switch which connects the capacitor or the battery to the excitation control circuit as a power supply source.

The regulator/brush-holder assembly (1) comprises a support (2) and an electrical circuit (5, 6) comprising a regulating element (5) connected by microwires to a trace circuit (6). The electrical circuit further includes a filtering circuit (10) separate from the regulating element and connected by microwires to the trace circuit. According to one particular embodiment, the filtering circuit comprises an insulating substrate (11) and surface-mounted components (C1, C2, S1, S2, V). A ground plane (19) and/or one or more ground pads may be provided for connection to a ground trace of the trace circuit. The filtration frequencies of the filter circuit extend from 100 kHz to 1 GHz.

A method for converting heat to electric energy is described which involves thermally cycling an electrically polarizable material sandwiched between electrodes. The material is heated using thermal energy obtained from: a combustion reaction; solar energy; a nuclear reaction; ocean water; geothermal energy; or thermal energy recovered from an industrial process. An apparatus is also described which includes an electrically polarizable material sandwiched between electrodes and a heat exchanger for heating the material. The heat source used to heat the material can be: a combustion apparatus; a solar thermal collector; or a component of a furnace exhaust device. Alternatively, the heat exchanger can be a device for extracting thermal energy from the earth, the sun, ocean water, an industrial process, a combustion reaction or a nuclear reaction. A vehicle is also described which comprises an apparatus for converting heat to electrical energy connected to an electric motor.

A thermionic generator for converting thermal energy to electric energy includes: an emitter electrode for emitting thermal electrons from a thermal electron emitting surface when heat is applied to the emitter electrode; a collector electrode facing the emitter electrode spaced apart from the emitter electrode by a predetermined distance, and receiving the thermal electrons from the emitter electrode via a facing surface of the collector electrode; and a substrate having one surface. The emitter electrode and the collector electrode are disposed on the one surface of the substrate, and are electrically insulated from each other. The thermal electron emitting surface and the facing surface are perpendicular to the one surface.

A method of operating a converter of a wind turbine for providing electric energy to a utility grid includes determining a grid voltage. If the grid voltage is between a nominal voltage and a first voltage threshold, i.e. higher than the nominal voltage, a normal procedure for lowering the grid voltage is performed. If the grid voltage is above the first voltage threshold, another procedure for keeping the wind turbine connected is performed, wherein the other procedure is different from the normal procedure. Further a corresponding arrangement is described.

The present invention discloses a method and an apparatus for power control. An apparatus for power control in accordance with an embodiment of the present invention can include: a voltage comparing part configured to compute an error voltage by using a measured voltage measured at the generator and a reference voltage that is designated; a control module configured to compute a first reactive power value for power control of the generator by being inputted with the error voltage; and a driving module configured to compute a reference reactive power value by using the first reactive power value and a second reactive power value computed using an active power value of the power converter and configured to control the power converter in correspondence with the computed reference reactive power value.

A system, method and apparatus for automatically adapting power grid usage by controlling internal and/or external power-related assets of one or more users in response to power regulation and/or frequency regulation functions in a manner beneficial to both the power grid itself and the users of the power grid.

An AC current generator for generating an CA current and method therefor and includes a stator and a rotor. The stator includes an outer shell of non-magnetic material enclosing an evacuated chamber and having a distribution of a plurality of ferromagnets attached thereto. The rotor includes an inner core of non-magnetic material located at a stability location within said evacuated chamber and having a distribution of a plurality of diamagnets attached thereto. In addition, the AC current generator includes at least one magnetic flux detection unit located within at least one magnetic field generated by at least one group of ferromagnets of the plurality of ferromagnets. Displacing the rotor from the stability location towards the at least one group of ferromagnets generates a change in magnetic flux in the magnetic field thereby generating an AC current in the at least one magnetic flux detection unit.

The rotary electrical machine is capable of functioning as a generator and outputs a continuous output voltage (Ub+) that is adjustable by an excitation current. The digital regulator (2) of the machine comprises an excitation current control means (7) and a control loop (6) that includes a device (10) for measurement, by sampling, of the output voltage (Ub+), the measurement device generating a signal sampled at a predetermined first sampling frequency (F1 e). The machine has a bandwidth that is limited by a predetermined first cutoff frequency (F1 c). The measurement device includes an apparatus for oversampling such that the first sampling frequency (F1 e) is greater than twice the first cutoff frequency (F1 c), and the control loop also includes an apparatus (12) for decimating the sampled signal.

Wind turbine systems and methods are provided. An exemplary system includes a wind driven doubly fed induction generator having a rotor and a stator, the stator providing AC power to a stator bus. The system further includes a power converter coupled to the rotor of the doubly fed induction generator, the power converter providing an output to a line bus, and a transformer coupled to the stator bus. The system further includes a solid-state switch coupled between the stator bus and the transformer.

A generator drive system for the generator (3) of an internal combustion engine (1), including a flexible drive having a traction mechanism (5) which is guided across a generator pulley (6) driving the generator (3). The generator (3) is configured and electrically wired such that the generator (3) can be temporarily driven as a motor, and the generator (3) is coupled to the generator pulley (6) or the crankshaft pulley (7) is coupled to the crankshaft (8) via an overrunning clutch (4) which allows the generator (3), when operated as a motor, running faster than the generator pulley (6) or, taking into consideration a gear ratio, the crankshaft (8).

Systems and methods for reducing current imbalance between parallel bridge circuits used in a power converter of a doubly fed induction generator (DFIG) system are provided. A control system can monitor the bridge current of each of the bridge circuits coupled in parallel and generate a feedback signal indicative of the difference in bridge current between the parallel bridge circuits. Command signals for controlling the bridge circuits can then be developed based on the feedback signal to reduce current imbalance between the bridge circuits. For instance, the pulse width modulation of switching devices (e.g. IGBTs) used in the bridge circuits can be modified to reduce current imbalance between the parallel bridge circuits.

A method is employed for operating a wind turbine. Electrical energy is produced by means of a generator and is fed into an electrical power network. The electrical energy is fed to the secondary side of a transformer at a low voltage and is output on the primary side of the transformer at a higher voltage. The potential on the primary side of the transformer is undefined. In the method, a measured value of the voltage between the primary side of the transformer and the earth potential is first recorded. The measured value is compared with a predefined limit value. The electrical energy produced by the generator is changed if the measured value exceeds the limit value. A wind turbine is designed to carry out the method. Faults in the medium voltage network can be reacted to without an additional star point on the primary side of the transformer being required.

A double fed induction generator (DFIG) converter method are presented in which rotor side current spikes are attenuated using series-connected damping resistance in response to grid fault occurrences or grid fault clearances.

An arrangement adapted for letting water pass by electrical conductors and their contact surfaces related to a track of a system adapted for electrically driving a vehicle along a roadway. The vehicle is provided with a current collector which is displaceable up and down and sideways in relation to the direction of transportation, in order to be brought into mechanical and electrical contact with elongated tracks positioned below the roadway and comprising a conductor adapted to be supplied with current and put under voltage. At least two or three tracks are disposed parallel to each other in a common rail structure, with at least two of these tracks being adapted to support and contain individual electrical conductors with contact surfaces put under voltage, and wherein at least one track is disposed closer to the highest point of the roadway and adjacent to a track containing one of said conductors with contact surfaces, which may be put under voltage.

The present invention has its application to a system for driving an electric and by one or more batteries powered vehicle along a roadway, comprising “a” one or more vehicles, which may be driven by an individual electric motor or motors and where in the respective vehicles exhibit a power-controlling control circuit for creating the necessary power and/or speed control and wherein required power i.a. can be provided primarily by a chargeable can be provided primarily by a chargeable battery set associated with the vehicle and “b” a plurality of road sections road portions divisible for the roadway, each being allotted one or more vehicle external electric stations for charging the battery set thereby and/or for supplying necessary power and energy for driving the vehicle. The underneath side of the mentioned vehicle is provided with a contact means displaceably positioned up and down and sideways, counted in the direction of transportation. Said roadway and its road sections or portions exhibits an elongated track or groove, each road section is supporting two rails in the groove and disposed under the driving path of the road section or portion. The rails being supplied with current and voltage. Said contact means is coordinated with a control equipment for creating simple adaptation of the contact means for registering the contact means for mechanical and electrical contact against said two rails.

A wireless power feeder 116 feeds power from a feeding coil L2 in the ground to a receiving coil L3 incorporated in an EV by wireless using a magnetic field resonance phenomenon between the feeding coil L2 and receiving coil L3. A plurality of feeding coils L2a to L2d are buried in the ground. Receivers 112a to 112d are buried in corresponding respectively with the feeding coils L2a to L2d. The plurality of receivers 112 each receive a position signal transmitted from a transmitter 110 of the EV. A feeding coil circuit 120 supplies AC power to the feeding coil L2 corresponding to the receiver 112 that has received the position signal to allow the feeding coil L2 to feed power to the receiving coil L3 by wireless.

A spooling apparatus includes a spool for holding wire, the spool having a wire-retaining section and end plates, the end plates having one or more apertures. A conductive plate is positioned on an end plate of the spool opposite the wire-retaining section, and at least one conductive extension that extends through a corresponding aperture of the end plate such that the conductive extension is adjacent to the wire retaining section. Wire is spooled onto the wire-retaining section, at least a portion of the wire being uninsulated and in electrical contact with the conductive extensions of the conductive plate.

A mobile device case includes a reel assembly, including a reel, a supporting plate, and a hub between the reel and the supporting plate. The hub includes a first cavity between the hub and the supporting plate for housing a spring, and a second cavity between the hub and the reel for housing a flat flexible cable (FFC). The spring is wound in a first direction, while the FFC is wound in a second direction. The FFC includes a first end for electrically coupling to a female jack connector of a device. A female connector is electrically coupled to a second end of the FFC for engaging a male jack connector of user-provided headphones. When the reel rotates in the first direction, the spring tightens and the FFC loosens. When the reel rotates in the second direction, the spring loosens and the FFC tightens.

It is provided a power supply device and a power acquisition device for an electromagnetic induction-powered electric vehicle that increase a power transfer efficiency by maximizing a lateral deviation tolerance and by minimizing a gap between the power acquisition device and the power supply device while preventing the power acquisition device from colliding with an obstacle present on a road and being damaged by the collision.