Abstract: A DC power supply and a method for operating a DC power supply, wherein the DC power supply comprises at least one feedback-controlled preregulator, at least one feedback-controlled postregulator supplied by the feedback-controlled preregulator, output terminals for supplying regulated constant current or regulated constant voltage to a load, and a control unit for controlling at least one of the feedback-controlled preregulator and the feedback-controlled postregulator, and designed for adjusting a voltage offset or a current offset added to a signal in a feedback loop of at least one of the feedback-controlled preregulator and the feedback-controlled postregulator.

Abstract: The present disclosure is directed to an electrosurgical generator including a resonant inverter having an H-bridge and a tank. A sensor array measures at least one property of the tank. A pulse width modulation (PWM) controller outputs a first PWM timing signal and a second PWM timing signal to the H-bridge. The PWM controller controls a dead-time between the first PWM timing signal and the second PWM timing signal based on the at least one property measured by the sensor array.

Abstract: A DC power supply and a method for operating a DC power supply, wherein the DC power supply comprises at least one feedback-controlled preregulator, at least one feedback-controlled postregulator supplied by the feedback-controlled preregulator, output terminals for supplying regulated constant current or regulated constant voltage to a load, and a control unit for controlling at least one of the feedback-controlled preregulator and the feedback-controlled postregulator, and designed for adjusting a voltage offset or a current offset added to a signal in a feedback loop of at least one of the feedback-controlled preregulator and the feedback-controlled postregulator.

Abstract: A low-dropout voltage regulator includes a power transistor configured to receive an input voltage and to provide a regulated output voltage at an output voltage node. The power transistor includes a control electrode configured to receive a driver signal. A reference circuit is configured to generate a reference voltage. A feedback network is coupled to the power transistor and is configured to provide a first feedback signal and a second feedback signal. The first feedback signal represents the output voltage and the second feedback signal represents an output voltage gradient. An error amplifier is configured to receive the reference voltage and the first feedback signal representing the output voltage. The error amplifier is configured to generate the driver signal dependent on the reference voltage and the first feedback signal. The error amplifier includes an output stage that is biased with a bias current responsive to the second feedback signal.

Abstract: A circuit arrangement is for operating a load having a reactive characteristic on an AC power supply. The circuit arrangement enables the best possible reactive power compensation, that is, enables operation close to a cos ? of 1, in order to increase the overall efficiency of the arrangement or to achieve optimal energy savings. In order to control critical operating states, a feedback loop is provided that supplies a control current to a further reactive circuit element. This further circuit element is arranged parallel to the load or to the power factor correction capacitor, and is acted upon by a control current such that the control current counteracts a change in the reactive component of the load. The control current is derived from the load current as a variable proportional to the load current. In this way, a reactor for optimizing electromagnetic consumption is created.

Abstract: A light emitting element drive device includes an electric conduction switch that is provided along a power input line, a voltage detection unit that detects a power source voltage containing a noise component when the electric power is supplied to the power input line, a conversion processing unit that converts the detected power source voltage containing the noise component to a digital value, a data generation unit that generates data of a predetermined number of bits, and a control unit that turns on the electric conduction switch. The control unit determines a delay time based on the predetermined number of bits. The delay time corresponds to a time between supplying the electric power to the power input line and turning on the electric conduction switch. The control unit turns on the electric conduction switch after the delay time passes. Thus, an excessive rush current is prevented.

Abstract: An electronic current transformer (ECT) based on complete self-excitation power supply is provided. The ECT includes an energy-obtaining coil, a rapid voltage-stabilizing circuit and an Analog/Digital (A/D) converting circuit. The output of the energy-obtaining coil is connected with the input of the voltage-stabilizing circuit. The output of the voltage-stabilizing circuit is connected with the control end of the A/D converting circuit. The ECT uses two branch circuits to obtain energy directly from the magnetic field of a bus bar to be measured respectively, synthesizes two output waveforms to fill the wave trough of each other, and reduces the pulse of direct current. In this way, the trough voltage of the synthesized wave is higher than the required stabilizing value of direct voltage and it directly meets the input requirement of the stabilizing module of the voltage-stabilizing circuit. As a result, the ECT can activate the A/D converting circuit rapidly.

Abstract: A power supply circuit includes a pulse width modulation (PWM) chip, a number of phase circuits, a voltage output end, and a spike suppression circuit. The spike suppression circuit is connected to each of the phase circuits and the voltage output end. The PWM chip controls all of the phase circuits to alternately output power supply voltages according to a predetermined sequence. The spike suppression circuit receives the power supply voltages, and filters out voltage spikes in the power supply voltages, thereby outputting steady voltages to the voltage output end.

Abstract: A single-phase voltage source AC/DC converter according to the present invention generates a second axis voltage command from difference between a DC voltage detection value at a DC terminal and a DC voltage command value and controls a DC voltage by increasing and decreasing active power with the second axis voltage command. For example, the voltage at the DC terminal is increased by decreasing active power when the DC voltage detection value at the DC terminal is lower than the DC voltage command, while the DC voltage detection value at the DC terminal is decreased by increasing the active power when the DC voltage detection value at the DC terminal is higher than the DC voltage command.

Abstract: A power converter stabilizes a voltage by controlling leading of an AC current and performs maximum charging within contracted power reception amount when connected to a weak power system. The power converter comprises Magnetic Energy Recovery Switch comprising a bridge circuit including at least two reverse conductive type semiconductor switches and a magnetic energy accumulating capacitor with a small capacity connected between DC terminals of the bridge circuit. The power converter uses the Magnetic Energy Recovery Switch to perform power conversion from AC to DC or vise versa. Plurality of secondary battery charging devices each comprising the power converter have a DC part connected to a common DC bus bar, so that power is accommodated among the secondary battery charging devices.

Abstract: A power factor correction converter includes a diode bridge that rectifies an alternating-current voltage input from an alternating-current input power supply Vac, a series circuit including an inductor and a switching element, a rectifying smoothing circuit connected in parallel with the switching element and including a diode and a smoothing capacitor, and a digital signal processing circuit that controls turning on and off of the switching element such that the input current input from the alternating-current input power supply Vac comes to have a similar shape to the alternating-current voltage. The current flowing through the inductor in the off period of the switching element is detected by using a current detection resistor, the operation mode is determined on the basis of the inductor current IL at a predetermined timing and the switching element is optimally controlled in accordance with the operation mode.

Abstract: A power conversion system with zero-voltage start-up mechanism and a zero-voltage start-up device are disclosed. The system includes a power conversion circuit, a power factor correction unit, a storage capacitor, a storage switching unit, and a zero-voltage detection module. The storage switching unit is serially connected with the storage capacitor, and particularly controlled by the zero-voltage detection module. The zero-voltage detection module detects a timing as an input voltage is at low level, and then outputs a control signal to turn on the storage switching unit. Therefore, the present invention assures that the power conversion system is turned on when the input voltage is at the low level, in order to suppress the system from a surge current.

Abstract: A method for operating a circuit arrangement is provided. The method may include coupling a second connection of a control device to a connection that provides an alternating signal during operation of the circuit arrangement; in the control device: generating a trigger signal for the control electrode of the mode switch that is correlated with the sum signal from the signal at the connection for providing an alternating signal and the control signal; and providing the trigger signal at the output of the control device.

Abstract: A multiple-output switching power source apparatus includes a control circuit to adjust a time for applying a DC voltage to a primary winding of a transformer by turning on/off a switching element Q1, a first rectifying-smoothing circuit for a first secondary winding of the transformer, a second rectifying-smoothing circuit for a switching element Q2 to provide a second output voltage connected to an output terminal of the first rectifying-smoothing circuit through the switching element Q2, a third rectifying-smoothing circuit for a second secondary winding of the transformer and provide a third output voltage, a first end of the second secondary winding of the transformer being connected to the switching element Q2, and a control circuit 13 to adjust an ON/OFF time of the switching element Q2 according to the voltage of the first secondary winding of the transformer, the second output voltage, and the third output voltage.

Abstract: A power supply module is configured for converting an AC voltage to a first DC voltage and applying the first DC voltage to a load. The power supply module includes a rectifying and filtering unit, a PFC unit, a voltage transforming unit, an input port, and a switch unit. The rectifying and filtering unit rectifies the AC voltage into a primary DC voltage and filters the primary DC voltage. The PFC unit corrects a power factor of the filtered primary DC voltage. The voltage transforming unit converts the corrected primary DC voltage and generates the first DC voltage for applying the load. The input port receives a first instruction or a second instruction and generates a first signal or a second signal, respectively. The switch unit establishes or disconnects an electrical connection between the voltage transforming unit and the load according to the first signal or the second signal.

Abstract: A thyristor power control circuit reduces EMI and maintains a holding current in the thyristor to prevent flickering at a load. The power control circuit includes a thyristor configured to receive an input AC voltage, and responsive to a gate pulse generates a modified AC voltage. A rectifier receives the modified AC voltage and generates a rectified DC voltage. A power converter coupled to the rectifier receives the rectified DC voltage and generates a controlled output current. A damping circuit coupled to an output terminal of the rectifier includes a damping resistor for maintaining the holding current in the thyristor during an ON period of the thyristor. The damping circuit includes a first capacitor coupled in series to the damping resistor and a diode coupled in parallel to the damping resistor. The diode enables the first capacitor to discharge without causing power loss at the damping resistor.

Abstract: The invention relates to a power supply system (3) intended to supply power to an electrical load (C), the system comprising: two input terminals, namely a negative terminal and a positive terminal, connected to a supply mains (A) delivering an AC voltage; an input capacitor (C1) connected to one of the terminals of the system; a rectifier module (33) for generating a DC voltage on a DC bus from the AC voltage; a bus capacitor (Cb) connected between a positive line (31) and a negative line (32) of the DC bus, and upstream of the input capacitor (C1), two normally-on bidirectional semiconductor transistors (T1, T2) connected in series, fabricated in a wide-bandgap material and able to operate in current-limiting mode.

Abstract: An uninterruptible power supply (“UPS”) has a phase-controlled rectifier coupled to a source of AC power and having an output providing a DC bus, the output of the phase-controlled rectifier coupled to an inverter. A first controller generates a firing angle for the rectifier and a fuzzy logic controller generates a firing angle for the rectifier. In an aspect, the rectifier is controlled by the firing angle generated by the first controller during normal operating conditions of the UPS and the rectifier is controlled by the firing angle generated by the fuzzy logic controller during abnormal operating conditions of the UPS. The abnormal operating conditions can include loss of a direct DC bus voltage measurement and or a period of time after the UPS experiences a large load change.

Abstract: Methods and apparatus to control a digital power supply are disclosed. An example method includes controlling a power factor controller by: receiving a first current signal flowing in a first stage of the power factor controller, receiving a second current signal flowing in a second stage of the power factor controller, determining a difference between the first current signal and the second current signal, determining if the magnitude of a measured current signal is above a predetermined threshold, activating an integrator to integrate the difference when the magnitude of the measured current signal is above a predetermined threshold, and outputting a first control signal and a second control signal to the power factor controller based on the output of the integrator.

Abstract: An output buffer circuit that suppresses the generation of an erroneous operation signal during power activation includes a first level converter generating a first signal based on a data input signal having an amplitude range between a first power supply potential and a ground reference potential. The first signal has an amplitude range between a second power supply potential, which differs from the first power supply potential, and the ground reference potential. A second level converter generates a second signal having an amplitude range between the second power supply and ground reference potentials based on a control input signal having an amplitude range between the first power supply and ground reference potentials. The first signal falls with a delay from the second signal. An output circuit generates an output signal. A timing adjustment circuit compensates for the fall delay of the first signal during power activation.

Abstract: Systems and methods presented herein generally provide for the controlled voltage of electrical energy through the selected operation of power stages. In one embodiment, a system that provides electrical energy includes a power supply and at least two power stages coupled to the power supply. The power stages are operable to selectively output electrical energy. By selecting the number of power stages which are turned on at a given time the total voltage of the electrical energy is controlled at that time. The use of air core magnetic flux coupling provides a unique, easily insulated method to provide power to the voltage stages at different potentials relative to each other. The system may further include one or more controllers coupled to the power stages to control selection of the power stages and thereby vary the output voltage.

Abstract: A device that includes an active rectifier (14) having control gates controllable to produce an output voltage on a DC bus (20), a gate control circuit (16) for producing gate control signals for controlling the active rectifier control gates, a first circuit (18) connected to the gate control circuit (16) and producing a command current magnitude signal and a power factor signal for use by the gate control circuit (16), a current line (30) providing a current related to the DC load current to the first circuit (16), and a voltage line (32) providing a voltage related to the DC bus voltage to the first circuit (16), the first circuit (16) including a peak detector (64) detecting current peaks on the DC bus (20), a command current magnitude signal generator (34) commanding a current as a function of the detected peaks, and a power factor controller (33, 40) varying the power factor signal (42) to control the voltage on the DC bus (20).

Abstract: There is disclosed a power converter having limited inrush current and an inrush current limiter circuit. The inrush limiting circuit may be a self-oscillating switching-mode average current regulator tp provide a relatively constant average charging current to a bulk capacitor until the bulk capacitor is fully charged. A bypass switch may be used to route current around the inrush current limiter circuit once the bulk capacitor is fully charged.

Abstract: A power factor controller for a switching power supply, that in one embodiment couples a power factor control circuit between an AC input and an output wherein a digital controller computes circuit currents for regulating the power supply without direct current measurements.

Abstract: A power converter that includes a transformer, a bridge input circuit, a self-driven synchronous rectifier circuit, a gate drive circuit, and a gate drive shutdown circuit. The transformer includes a primary winding connected to the bridge input circuit, a first secondary winding, and a second secondary winding. The self-driven synchronous rectifier circuit is connected to the first secondary winding and includes a first synchronous rectifier for rectifying a voltage across the first secondary winding. The first synchronous rectifier includes a control terminal responsive to a voltage across the second secondary winding. The gate drive circuit includes a first diode connected to the control terminal of the first synchronous rectifier for introducing a dc level shift thereto.

Abstract: Methods and apparatus are disclosed for suppressing circuit noise due to parasitic elements in switch mode power supplies. The presented embodiments use actively controlled damping devices such as controllable resistors, current sources, and tri-state power devices to achieve required damping and to minimize power loss.

Abstract: In a switch mode power supply, a mains supply voltage source is coupled to a rectifier for producing an input supply voltage. The rectified input supply voltage is coupled unfiltered to an input of the SMPS. A switching power transistor having a controllable duty cycle is controlled by a duty cycle modulated signal for producing a regulated output supply voltage from the rectified input supply voltage. The periodic waveform of the mains supply voltage is used to establish the timings of the duty cycle modulated signal. In each cycle, current flow is initiated in the transistor, when the transistor is already fully turned on and a voltage developed between its main current conducting terminals is low or close to zero volts. When the output supply voltage attains the required level the transistor is turned off. Hysteresis is provided for preventing the transistor from turning on again in the same cycle, after it has been turned off.

Abstract: A voltage converter includes two input terminals, at least a current limiting portion, an electronic switch in the form of a transistor controlled by a control device in synchronization with the supply voltage, and a storage capacitor. Two output terminals taken from the storage capacitor supply the load, where the current limiting portion is formed by at least the primary of a transformer, and whose secondary output supplies a rectifier whose output terminals are connected to the load.

Abstract: The invention relates to a combined AC-DC to DC converter. The converter provides the option of coupling to an AC supply source with at least one phase and the further option of coupling to at least one DC supply source. The converter obtains supply from at least one supply source at a time; and the converter contains controllable contact means that are, upon switching between supply sources, capable of connecting and disconnecting the individual supply sources to/from the converter; whereby a pulse signal is generated. The converter contains at least one coil that is in connection with at least one DC output.

Abstract: A power supply has an output circuit for a secondary stage of a converter that switches on and off a switching device such that the output voltage of the converter is regulated across a capacitor without use of an inductor in the output circuit. For example, the switching device is a semiconductor field effect transistor controlled by a comparator. The output circuit may be used with a switch mode power supply comprising a coreless, planar isolation transformer.

Abstract: Uninterruptible Power Supply (UPS) systems and methods for a communications signal distribution system, such as a cable television (CATV) signal distribution system that distributes a communication signal and an Alternating Current (AC) power over a coaxial cable having a conductor and a sheath, include an input neutral line and an input voltage line. A first circuit is configured to convert an input voltage between the input neutral line and the input voltage line into first and second complementary Direct Current (DC) voltages. A second circuit is configured to convert the first and second complementary DC voltages into an AC voltage between an output neutral line and an output voltage line, and to connect the output neutral line to a coaxial cable sheath and the output voltage line to a coaxial cable conductor. The first and second circuits are configured to connect the input neutral line to the output neutral line without an intervening transformer winding.

Abstract: A phase controlled drive circuit includes a drive circuit operable to provide gate signals to an SCR bridge circuit and a phase control circuit. The phase control circuit includes a first phase generator operable to generate a first phase signal, and a second phase generator operable to generate a second phase signal. The second phase signal is periodically reset to an initial value. A drive circuit actuator in the phase control circuit is operable to place the drive circuit in a first activation state when a sum of the first and second phase signals exceeds a threshold value, and is further operable to place the drive circuit in a second activation state when the sum of the first and second phase signals is less than the threshold value.

Abstract: A permanent magnet alternator including a stationary stator including a plurality of spaced stator poles projecting inwardly from the stator, a winding circuit wound through the spaces between the stator poles, a rotor assembly mounted for rotation within the stator, including a plurality of permanent magnets fixedly mounted on an outer circumferential surface of the rotor in alternating polarity, and a retaining shield for reducing the effects of centrifugal motion of the rotor during operation of the alternator.

Abstract: A control circuit for use with a switch power converter is disclosed. The control circuit includes a capacitor device electrically connected between a variable resistor of the feedback circuit and ground in series, a first divider resistor electrically connected between the variable resistor and the controlled switch circuit in series, a second divider resistor electrically connected between the first divider resistor and ground in series, and a controlled switch electrically connected among the controlled switch circuit, the first divider resistor and ground. The variable resistor has a resistance varying with a voltage value of the load. Furthermore, when an overall voltage value of the first and second divider resistors varies with the resistance of the variable resistor to switch the controlled switch for further optionally enabling the controlled switch circuit to allow the transformer with the peripheral circuit to process the energy transformation.

Abstract: A preconditioner comprises a rectifier, a switch mode power supply, and a feedback path for feedback of a preconditioner output voltage to a control block. The rectifier is arranged to receive an AC voltage from a voltage supply and to rectify the AC voltage. The switch mode power supply is arranged to control the current in the rectifier. The control block has a bandwidth equal to or greater than the voltage supply frequency. The feedback path has a bandpass filter connected to the output voltage and generates a feedback signal based on the output voltage and an output signal from the bandpass filter. The feedback signal has reduced ripple around the passband of the filter.

Abstract: A boost converter topology is disclosed that includes a resonant network comprising a snubber inductive element having a primary winding connected in series to a first resonant diode that is connected, at a first node, to two series connected additional resonant diodes and a secondary winding coupled to a fourth resonant diode connected to the first node. The present invention has the advantage of reducing the energy stored in the parasitic capacitor of the first resonant diode by a factor of four at the turn off of the main control switch. This reduction is achieved by allowing only a small amount of energy transfer to the snubber inductive element so that it does not turn the two additional resonant diodes on before the auxiliary switch is turned on, thus reducing losses and EMI associated with turning on the auxiliary switch.

Abstract: A device for producing electricity, the device comprising a three-phase alternator comprising three windings, a rectifier for converting the AC delivered by the alternator into rectified current, and a voltage-raising chopper using the self-inductance of the alternator to raise the voltage. The device includes a switch unit enabling the three windings to be connected either in a star configuration when the alternator is being rotated to produce electricity, or else to the respective phases of a three-phase network when the alternator is stopped.

Abstract: A regulator system includes a circuit regulating the output of a power supply such as a capacitive input filter power supply and preferably also a transformer and full-wave diode bridge.

Abstract: A voltage-source converter is connected on its ac-voltage side to a three-phase electric power network via a transformer and on its dc-voltage side to capacitor equipment. The transformer has on its secondary side a first, a second, and a third phase winding, each one with a first and a second winding terminal. Resistor equipment is arranged at the transformer for limiting the current through the converter when connecting the transformer to the power network.

Abstract: An in-rush current controller for a mains power rectification circuit including a fill wave rectifier and a capacitor. A serial resistor suppresses in-rush currents. The controller includes a sensing circuit that controls a pair of silicon controlled rectifiers to cyclically shunt or isolate the resistor during normal operation. Thus, power is not dissipated by the resistor and undesirable heat is not generated during normal operation. The sensing circuit responds to abrupt rises in voltage (typical of in-rush current conditions) to inhibit turn ON of the rectifiers so that the resistor is not shunted or isolated at such times.

Abstract: Switched power converter with hold-up time and harmonics reduction connected to an AC power mains through a first rectifier means (13) and connected to conversion means (19) supplying a regulated voltage. An energy storage means (16) connected in parallel with the rectifier means (13), absorbs or supplies current to the conversion means (19), by adapting the conducting periods of two switching devices in such a way that determines the voltage level on the storage means (16) and assures a sinusoidal current at input terminals (11, 12). The two switching devices are switched in a complementary manner by means of a first control means included in the energy storage means (16).

Abstract: An output voltage of a rectification smoothing circuit is compared with a reference voltage. When a reduction in the output has been detected, an A/D converting circuit converts a result of the comparison which is negatively fed back by an output voltage feedback circuit to obtain a control signal for a bidirectional switch element inserted into a primary side of a transformer so as to turn ON or OFF synchronously or asynchronously with a commercial power supply via an intermittent control circuit.

Abstract: In a method for stabilizing a power supply network against fluctuations of the reactive power of an electrical system, in particular of an arc furnace (5), having at least one transformer (3), the at least one transformer (3) is switched on and off on the supply network side in switching sequences which result in a fundamental-frequency power factor with a value at least approximately equal to 1. The fundamental-frequency reactive power is thus at least approximately equal to zero.

Abstract: A power supply circuit for an electronic thermostat includes a half wave rectifier, at least one voltage dropping resistor and a gated rectifier. The gated rectifier preferably conducts only when the voltage at its output drops below the voltage at its gate. The voltage at the gate is defined by gating circuitry downstream of the voltage dropping resistors. The intermittent conduction of the silicon controlled rectifier produces less current flow through voltage dropping resistors within the power supply circuit. This causes less heat dissipation by these resistors within the thermostat.

Abstract: A switching regulator device for charging applications includes a transformer (18) which receives an AC input signal from an AC source (12) which is then rectified with a bridge rectifier (24). A regulation control circuit (26) is provided for regulating the output level of the bridge circuit (24) to a load (20). The regulation circuit (26) includes a switching element (62) which is operable to draw current from the AC source (12) in a periodic manner. The on/off duty cycle of the control to the switching element (62) will allow energy to be stored in a leakage inductance (36) of the transformer (18). The transformer (18) therefore comprises the switching inductance of a switching power supply with the leakage inductance (36) designed to provide adequate regulation for the voltage and current supplied to the load (10).

Abstract: The active capacitor regulating type controllable voltage and current power supply circuit is disclosed with a voltage reducing and current limiting rectifying circuit which is constituted by capacitors and a bridge type current rectifier device, wherein it is characterized in that the output terminals of the rectifying circuit are parallel installed with a current distributing circuit device, thereby to actively control the output voltage setting status.

Abstract: A voltage regulator (12) for controlling and limiting the output voltage of an alternator (10) includes a control circuit having a full wave rectifier (28) for impressing a series of half wave pulses (32) onto a first circuit (34) in correspondence to the output of the alternator (10). A gate controlled switch (36) is utilized to conduct the half wave pulses (32) to the output circuit (24) when a gate signal is present. A voltage detector (44) monitors the output voltage and shunts the gate signal to ground when the output voltage reaches a given upper value and removes the shunt when the output voltage recedes to a given lower value.

Abstract: A two-wire power supply switch connected in series with a load between two poles of an alternating current mains electrical power supply conventionally includes a main triac between two terminals of the switch which is turned on by the conduction of an optotriac with a time-delay relative to the zero crossing of the voltage between the switch terminals determined by the breakdown voltage of a series of Zener diodes. The switch includes a power supply unit with a rectifier bridge connected to one terminal directly and connected to the other terminal via a capacitor. An auxiliary triac shunting the capacitor is turned on by the optotriac on each zero crossing of the voltage between the switch terminals. This optimizes conditions when the switch is open and when the switch is closed separately.

Abstract: An isolated forward switching power converter includes a primary side circuit and a secondary side circuit having an output inductor, a first MOS gated transistor coupled in series with the output inductor, a second MOS gated transistor coupled in shunt relationship with the output inductor, and a synchronous rectifier control circuit which senses the voltage across the output inductor and alternately biases the first and second transistors on and off in response thereto.

Abstract: A permanent magnet alternator including a stationary stator including a plurality of spaced stator poles projecting inwardly from the stator, a winding circuit wound through the spaces between the stator poles, a rotor assembly mounted for rotation within the stator, including a plurality of permanent magnets fixedly mounted on an outer circumferential surface of the rotor in alternating polarity, and a retaining shield for reducing the effects of centrifugal motion of the rotor during operation of the alternator.