Abstract: A Variable Frequency Drive (VFD) supplies power to rotate a motor, controlling both the speed and direction. The method normally used for this power conversion by the VFD results in energy losses and line harmonics. When the motor is driven by the VFD to be rotating at the same speed and direction as if the motor was straight across the incoming AC power, a transfer in power supply to the motor can be made using contactors to bypass the VFD. When in this bypass mode, the energy losses of the VFD are greatly reduced, and the line harmonics due to the VFD are greatly reduced. When it is subsequently recognized that the speed reference has deviated from being the same speed and direction as if the motor was straight across the incoming AC power, a transfer in power supply can be made from using contactors to once again drive the motor from the VFD.

Abstract: Exemplary embodiments are directed to a converter for an electrical system that is controlled in such that switching sequences for the converter, determined with respect to an optimization goal are modified such that by correcting a flux error resulting from assumptions on which the first optimization of the switching sequence is based.

Abstract: In one embodiment, a system for reducing component noise in a motor in a automobile includes a first gate driver and a second gate driver, a high side FET; a low side FET; a charge pump circuit; a high frequency reduction component; and a timing signal source.

Abstract: A device for driving an electric motor includes: an inverter circuit, configured for converting a d.c. supply signal into an a.c. supply signal; and a control block, connected to the inverter circuit and configured for controlling the inverter circuit by means of a pulse-width modulation, having a given cycle-period value. The driving device further includes a first random-number generator, connected to the control block and configured for supplying to the control block pseudo-random or random cycle-period values.

Abstract: The PWM control circuit is provided. The PWM control circuit includes: a PWM control signal generator that generates a PWM period signal defining a period of a PWM signal and a PWM resolution signal specifying a resolution in one period of the PWM period signal; and a PWM unit that generates the PWM signal based on the PWM period signal and the PWM resolution signal, wherein the PWM control signal generator changes a frequency of the PWM resolution signal while keeping a frequency of the PWM period signal unchanged.

Abstract: A motor control circuit for a motor is provided. The motor control circuit drives the motor based on torque command data. The torque command data is output by adding speed error data output from a speed error detecting section based on a first reference clock and a speed pulse and phase error data output from a phase error detecting section based on a second reference clock and the speed pulse. Each of the speed error data and the phase error data is output within a detection range set by a setting section provided for each of the speed error detecting section and the phase error detecting section.

Abstract: The invention relates to a frequency converter, which is fitted to supply power between a polyphase alternating electricity source and an electric machine. The frequency converter comprises a network rectifier connected to the alternating electricity source and an inverter connected to the electric machine. The power supply is implemented in the network rectifier and in the inverter with solid-state change-over switches, which change-over switches comprise an antiparallel-connected diode fitted in parallel with the controllable switch. The network rectifier and the inverter are connected to each other with an intermediate circuit, which intermediate circuit is implemented without a passive energy storage.

Abstract: An electric machine system includes an alternating current (AC) electric machine. The AC electric machine includes a machine housing having a machine portion and a switch portion. A stator is fixedly mounted in the machine portion of the machine housing and a rotor is rotatably mounted relative to the stator. A switch assembly is arranged within the switch portion of the machine housing and electrically connected to the stator. The switch assembly includes at least one switch module having at least one switch member. The at least one switch module is configured and disposed to be detachably mounted in the switch portion of the machine housing. A direct current (DC) power source is electrically connected to the stator through the switch assembly. A controller is operatively connected to the switch assembly.

Abstract: Techniques and apparatus for limiting the current through a motor, such as a motor for rotating a rotatable element of a hard drive. The current can be limited based on a threshold. A first threshold value can be set for a first time period. A second threshold value can be set for a second time period in which the current through the motor rises. The second threshold value is lower than the first threshold value. A spike in the supply current upon accelerating the rotatable element of the motor can thereby be reduced or eliminated.

Abstract: Power conversion systems with active front end converters for example motor drives and power generation systems for distributed energy sources are presented with adaptive harmonic minimization for grid-tie converters for minimized or reduced total harmonic distortion in the line current spectrum including the source harmonic current and the grid-tie converter injected current spectrum referred to the line side.

Abstract: A phase current estimation apparatus for a motor capable of suitably improving estimation accuracy of phase currents is provided. The phase current estimation apparatus 10 of the motor includes a control unit 24 that decomposes a command voltage vector Vdq into two vector components V?dq in the case where a magnitude of the command voltage vector Vdq is less than a predetermined lower limit voltage Vlow, so that the command voltage vector Vdq is allowed to have the magnitude equal to or more than the predetermined lower limit voltage Vlow for every two adjacent periods in units of a period of a carrier signal and to have the phase outside a predetermined phase range including phases of reference voltage vectors. Accordingly, the control unit 24 can quantitatively analyze harmonic components, which are generated by decomposing the command voltage vector Vdq into the two vector components V?dq, by using mathematical equations.

Abstract: A medium voltage variable frequency drive having a 2-high controller configuration with a dual bus system is described. The drive control system includes at least one motor control cabinet housing a fused medium voltage bypass controller, a non-fused transfer controller positioned above the fused medium voltage bypass controller, an extendable output bus coupled to the non-fused medium voltage transfer controller, and an extendable supply bus coupled to the fused medium voltage bypass controller. The drive control system further includes a variable frequency drive cabinet housing a variable frequency drive. The variable frequency drive is coupled to the extendable output bus and a power supply line. The power supply line may be further coupled to the extendable supply bus. The drive control system includes at least one cabling transition cabinet housing cabling between the at least one motor control cabinet, the power supply line, and the variable frequency drive.

Abstract: A power train for a transport vehicle is provided. The power train includes an electric motor comprising a shaft, a stator and a rotor, a power supply system receiving direct input voltage and delivering a polyphase voltage to the motor. The system has a modulation factor equal to the voltage amplitude of each phase of the motor divided by the direct input voltage, and includes a sensor for the rotational speed of the rotor.

Abstract: The present invention discloses media drive device that turns a media by a motor, read data from the media and/or write data on to the media, that is comprised of a speed control unit that outputs a control pulse signal to control rotational speed of the motor and set adjusting quantity of the rotational speed by changing duty ratio of the control pulse, and a voltage up circuit that voltage up and generates driving voltage for driving the motor by switching operation that is based on the duty ratio of the control pulse.

Abstract: A power converter that interfaces a motor requiring variable voltage/frequency to a supply network providing a nominally fixed voltage/frequency includes a first rectifier/inverter connected to a stator and a second rectifier/inverter. Both rectifier/inverters are interconnected by a dc link and include switching devices. A filter is connected between the second rectifier/inverter and the network. A first controller for the first rectifier/inverter uses a dc link voltage demand signal indicative of a desired dc link voltage to control the switching devices of the first rectifier/inverter. A second controller for the second rectifier/inverter uses a power demand signal indicative of the level of power to be transferred to the dc link from the network through the second rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at network terminals of the filter to control the switching devices of the second rectifier/inverter.

Abstract: In order to reduce the average power of the ringing noise, the present invention provides a power converter comprising: an arm circuit including a high-voltage side switching device to which a first diode is connected in parallel and a low-voltage side switching device to which a second diode is connected in parallel; and a main power supply connected to a series circuit of the high-voltage side switching device and the low-voltage side switching device, wherein a connecting point between the high-voltage side switching device and the low-voltage side switching device is connected to a load, and a resonant frequency calculated from inductances of wirings of a closed circuit including the first diode, the second diode, and the main power supply and a capacitance across the first diode is different form that calculated from the inductances of the wirings and a capacitance across the second diode.

Abstract: An electric motor, having a stator (465), a rotor (470), and an apparatus for evaluating a signal provided for controlling said motor (110), comprises a receiving unit (430, 440) for receiving a control signal (PWM_mod), which is a pulse width modulated signal (PWM) onto which a data signal (DIR, DATA) is modulated. An evaluation unit (440) is provided for evaluating the modulated control signal (PWM_mod). The unit is configured to extract, from the modulated control signal (PWM_mod), data provided for operation of the motor (110). The control apparatus includes a signal generator (450) configured to generate, on the basis of the extracted or ascertained data provided for operation of the motor (110), at least one control signal for the motor (110), such as a commanded direction of rotation. Piggybacking other control data onto the PWM power level signal reduces hardware investment, by permitting omission of a signal lead which would otherwise be required in the motor structure.

Abstract: An AC electric motor, an inverter and a controller are mounted on an electric powered vehicle. The controller includes a voltage deviation calculating unit, a modulation factor calculating unit, and a mode switching determination unit. The voltage deviation calculating unit calculates a voltage deviation between a first voltage command when the rectangular wave voltage control is executed and a second voltage command when pulse width modulation control is executed, by inputting a current deviation to a voltage equation of the AC electric motor. Modulation factor calculating unit calculates the modulation factor based on the first voltage command and the voltage deviation. The mode switching determination unit determines whether or not control mode of the AC electric motor from the rectangular wave voltage control to the pulse width modulation control is necessary, based on the modulation factor.

Abstract: A robotic device includes an electric motor in which a drive control circuit includes a driver circuit for intermittently supplying the magnetic coils with a supply voltage VSUP; a switching signal generating circuit that generates a switching signal supplied to the driver circuit; and a voltage setter that supplies a supply voltage control value Ya to the switching signal generating circuit. By adjusting pulse width of the switching signals DRVA1, DRVA2 with reference to the supply voltage control value Ya, the switching signal generating circuit adjusts the effective voltage which is applied to the magnetic coils.

Abstract: The invention concerns a method and an apparatus for controlling a three-or-more-phase motor driven by a frequency converter. In the method, a change-over switch of the frequency converter is controlled to a continuously conducting state and at the same time the phase voltages or phase currents of the other phases are controlled by switching the change-over switches in those motor phases at a switching frequency substantially higher than the frequency of the fundamental wave of the phase voltage or phase current. The apparatus comprises in conjunction with the frequency converter a number of change-over switches, at least one change-over switch for each motor phase. The change-over switches comprise controllable change-over contacts. The apparatus further comprises in conjunction with the frequency converter means for determining the motor phase currents and means for controlling the change-over contacts.

Abstract: A motor controller that outputs a drive signal to a direct-current motor to drive the motor is provided. The motor controller includes a drive circuit that generates the drive signal. The drive circuit superimposes on a direct-current voltage an alternating-current component having a frequency in the audible frequency range of the human ear, thereby generating the drive signal.

Abstract: According to one embodiment, a low frequency drive control circuit for use with an inductive load comprises a comparator configured to receive a high frequency signal at a first input and a smoothly varying low frequency signal for modulating the high frequency signal at a second input. The comparator is further configured to produce a pulse width modulated output of the low frequency drive control circuit for use in generating a smoothly varying low frequency load current in the inductive load. In one embodiment, the inductive load can comprise a DC brushed motor. In one embodiment, the low frequency drive control circuit can be implemented as part of an integrated circuit further comprising a switching circuit configured to use the pulse width modulated output of the comparator to generate the smoothly varying low frequency load current, which may be a substantially sinusoidal load current, for example.

Abstract: A motor drive circuit to drive a motor coil based on duty ratio of a PWM signal, includes: a first pulse signal generating circuit to generate a first pulse signal for each time period, the time period being equal to 1/n of a time period during which the PWM signal is at one logic level; a counter to change a count value based on the first pulse signal; a drive signal output circuit to output a drive signal of one logic level when the count value is not a predetermined value, and output the drive signal of the other logic level when the count value reaches the predetermined value; a drive circuit to perform PWM driving for the motor coil based on the duty ratio of the drive signal; and a setting circuit to set, in the counter, such a count value as to decrease a current passing through the motor coil, for each period of the PWM signal, in a time period during which the current passing through the motor coil is decreased, and set, in the counter, such a count value as to increase the current passing through th

Abstract: A DC motor system includes a plurality of speed taps coupled to an AC source and a variable speed DC motor. A circuit determines which speed taps are coupled to the AC source, outputs corresponding logic signals, and isolates digital circuits from the AC source. A digital logic device accesses from memory a value corresponding to the upper limit speed of the variable speed DC motor, determines a commanded motor speed based at least in part on the logic signals and the upper limit speed value, and outputs a pulse width modulated signal having a duty cycle corresponding to the determined commanded motor speed. A driver receives the pulse width modulated signal and outputs a corresponding signal. The variable speed DC motor receives the driver output signal, and rotates a rotor at a speed corresponding to the pulse width modulated signal duty cycle.

Abstract: A device for generating electric power of a traction system of a motor vehicle powered by a battery, including a first rectifier stage configured to be connected to a power supply network or to a load to be powered, a second inverter stage configured to be connected to the battery, a mechanism regulating average current flowing between the first stage and the second stage, and a controller controlling a transfer of electric power between the power supply network and the battery or the powering of a load.

Abstract: An energy conservation system that realizes optimized power demand control for alternating current electrical motors equipped with variable frequency drives is implemented by switching an electrical motor via bypass systems from a variable frequency and speed drive mode of operation to a constant frequency and speed drive mode of operation and from a constant frequency and speed drive mode of operation to a variable frequency and speed drive mode of operation. The switching from one mode of operation to another is automatically executed based on the comparative analysis of historical and current trends of the electrical motor actual power demand at variable and constant speed drive modes of operation at various loads. The system optimizes the electrical motor operation by selecting the mode with the lower magnitude of cumulative power demand for the motor and motor drive at a given motor load.

Abstract: The motor drive unit includes: an energized phase switch section; a power stage; a PWM control section; a torque comparison section configured to compare the voltage level of a torque command signal with the voltage level of a comparison reference signal; a comparison reference signal production section configured to produce the comparison reference signal; and an energization control section configured to drive the power stage by synchronous rectification PWM drive when the voltage level of the torque command signal is higher than the voltage level of the comparison reference signal, and by a scheme other than the synchronous rectification PWM drive when the voltage level of the torque command signal is lower than the voltage level of the comparison reference signal.

Abstract: Systems and methods for operating a variable speed drive to receive an input AC power at a fixed AC input voltage and frequency and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter stage to convert the input AC voltage to a boosted DC voltage, a DC link connected to the converter stage to filter and store the boosted DC voltage from the converter stage; and an inverter stage to convert the boosted DC voltage into AC power with variable voltage and the variable frequency. An integral bypass contactor is connected in parallel with the VSD between the AC power source and the AC output power. The integral bypass contactor is arranged to bypass the VSD when the VSD output frequency and voltage are approximately equal with the AC input voltage and frequency.

Abstract: A power supply and control unit for submersed electric motors includes an enclosure which is jointly connected to the motor of a submersed electric pump and forms a hermetic chamber that contains an electronic power supply that can be connected to the motor. The unit includes a heat exchange means in the liquid state that completely fills the empty space within the hermetic chamber yin order to transfer to the enclosure the heat generated by the electronic power supply.

Abstract: A power conversion device includes a power switching circuit that supplies AC voltages generated between switching elements operating as upper arms and switching elements operating as lower arms, and a control circuit that generates and supplies to the driver circuit signals for controlling the switching operation of the switching elements by a PWM method in a first operational region in which frequency of an AC power to be outputted is low, and that generates and supplies to the driver circuit signals for controlling the switching operation of the switching elements at timings based upon the phase of the AC power to be outputted in an operational region in which the frequency of the AC power to be outputted is higher than in the first operational region.

Abstract: To minimize switching losses in a rotating electrical machine, exemplary embodiments of the present disclosure proposes an iterative control method which calculates optimal switching states in advance. A rotating electrical machine can be controlled on the basis of this iterative control method.

Abstract: A method of operating a motor is disclosed. The motor has a nameplate operating frequency and at least a first and second wiring configuration for operating at a first nameplate voltage and second, higher, nameplate voltage, respectively. The method includes operating the motor in the first configuration at a frequency and a voltage based on a set of frequency versus voltage ratios over a range of frequencies. A first ratio in a lower portion of the frequency range is lower than a second ratio in a middle portion of the frequency range. A third ratio in an upper portion of the frequency range is lower than the second ratio. The range of frequencies extends from a value below the nameplate frequency to a value above the nameplate frequency. The corresponding range of voltages extends from a value below the first nameplate voltage to a value above the first nameplate voltage.

Abstract: A motor bypass is controlled by a digital signal processor (DSP) with embedded control software that allows fault detection and annunciation, serial communications between both a variable frequency drive (VFD) and a bypass controller and the bypass controller and a host computer. The use of the DSP and embedded control software further allows for contactor coil control to provide fault tolerant operation as well as fault condition detection and annunciation to the user.

Abstract: A control device that controls a plurality of inverters respectively provided corresponding to a plurality of alternating-current electric motors so as to control the plurality of alternating-current electric motors by current feedback. The control device comprises a carrier frequency setting unit that individually selects and sets one of a plurality of carrier frequencies, each of which is a frequency of a carrier for generating switching control signals for the inverter based on a pulse width modulation method, for each of the plurality of inverters, and a switching timing table that specifies a switching timing serving as a permissible timing of switching to a different carrier frequency pair from each of a plurality of carrier frequency pairs each of which is composed of a combination of the carrier frequencies set for each of the plurality of inverters.

Abstract: In an electric motor control apparatus, an electric motor driving unit includes: a current detection unit configured to detect a current flowing through a current detection place in the electric motor driving unit. A control unit includes a current calculation unit configured to calculate a current value of a current flowing through an electric motor from an offset correction value obtained based on a first detection value detected at a time when a current flows through the current detection place and a second detection value detected at a time when a current does not flow through the current detection place. The offset correction value includes: a first offset correction value stored in nonvolatile memory of the control unit at a time of assembling the electric motor control apparatus; and a second offset correction value computed by the control unit while the electric motor is driven.

Abstract: An apparatus operable in a wet environment for controlling the flow of electrical current to an electrical load, includes a pair of input terminals for connection to an AC mains supply; a pair of output terminals for connection to an electric motor and connected in a full power mode to the pair of input terminals; a voltage doubler circuit including a pair of diodes; a pair of direct current switching elements connected between the respective diodes and a common point; a controller; an interface connected to the controller for receiving external status signals; a switching arrangement responsive to signals from the controller to select the full power mode or a controlled power mode, and wherein in the controlled power mode the switching arrangement connects one of the output terminals to the common point so that AC output voltage is supplied to the electric motor through the switching elements.

Abstract: A two-phase or four-phase electric machine includes a first stator part and a second stator part disposed about ninety electrical degrees apart. Stator pole parts are positioned near the first stator part and the second stator part. An injector injects a third-harmonic frequency current that is separate from and not produced by the fundamental current driving the first stator part and the second stator part. The electric angular speed of the third-harmonic rotating field comprises p · ? t , where p comprises the number of pole pairs, ? comprises a mechanical angle and t comprise time in seconds.

Abstract: An axial gap type motor/generator is provided with a stator, a rotor and an alternating current control device. The alternating current control device executes alternating current control of a single phase or multiple phase alternating current flowing in the coils. The alternating current control device includes a superpositioning control section and a frequency component control section. The superpositioning control section produces the alternating current by superpositioning a plurality of frequency components including a first order fundamental wave component and a plurality of higher harmonic wave components that have frequencies equal to integer multiples of a frequency of the fundamental wave components and are of orders that are equal to values of the integer multiples. The frequency component control section controls a relationship among the frequency components such that two pairs of the frequency components whose orders differ by two are aligned with respect to each other.

Abstract: Method and apparatus for controlling an apparatus transmitting power between two electricity networks or between an electricity network and a polyphase electric machine (M/G), which electricity networks can be polyphase alternating-current networks or one of them can be a single-phase direct-current network, and which apparatus comprises low-voltage power cells (C), which comprise a single-phase output connection (OUT). The power cells also comprise a single-phase input connector (IN), the power cells are arranged into groups (G1-GN, GP1-GPN1, GS1-GSN2, G1??-GN??) such that at least one power cell per each phase of the electricity network or of the electric machine belongs to each group, and the input terminals (IN) of all the power cells belonging to the same group are connected to a common transformer, which transformer comprises its own separate winding that is galvanically isolated from the others for the power cell connected to it.

Abstract: A motor load control apparatus capable of suppressing heat generation of an electronic switch and suppressing occurrence of noise associated with rotation of a fan and vibration of the fan is provided. A switch section (17) in which a first electronic switch (T1) and a second electronic switch (T2) are connected in parallel is provided, and the first electronic switch (T1) is driven by a PWM signal with a predetermined duty ratio and a predetermined frequency and the second electronic switch (T2) is driven in a state of delaying the PWM signal by which the first electronic switch (T1) is driven by a predetermined time. Consequently, as compared with the case of one electronic switch, a heating value of each of the electronic switches can be reduced and radiation measures of the whole apparatus can be reduced. Further, noise or vibration occurring by PWM control can be reduced by changing delay time at random.

Abstract: The invention relates to a frequency converter, which is fitted to supply power between a polyphase alternating electricity source and an electric machine. The frequency converter comprises a network rectifier connected to the alternating electricity source and an inverter connected to the electric machine. The power supply is implemented in the network rectifier and in the inverter with solid-state change-over switches, which change-over switches comprise an antiparallel-connected diode fitted in parallel with the controllable switch. The network rectifier and the inverter are connected to each other with an intermediate circuit, which intermediate circuit is implemented without a passive energy storage.

Abstract: The present invention relates to a method for generating an electric control signal for controlling one or more switching elements of an inverter for driving an electric machine, such as a motor, the method comprising the steps of providing an electric control signal comprising a control frequency and a corresponding control period, dividing a first control period of said electric control signal into a plurality of switching periods, and providing a first switching PWM pulse within a first switching period of a first control period, and providing a second switching PWM pulse within a second switching period of said first control period, wherein the first switching PWM pulse is a minimum-filtered PWM pulse, and wherein the second switching PWM pulse is a corrected PWM pulse. The present invention further relates to an electronic control signal provided according to the before-mentioned method, and to an electronic control system for providing the before-mentioned method.

Abstract: A power converter circuit for providing maximum utilization of a DC bus voltage to a two-phase Permanent Magnet Synchronous Motor (PMSM) is disclosed. The circuit includes first, second, and third nodes, each node being the junction between series connected high and low side switches connected across a DC bus; a PMSM having first and second windings and a star point at which the first and second windings are coupled to each other, the first winding having a terminal connected to the first node, the second winding having a terminal connected to the second node, and the star point being connected to the third node; and a controller for performing a three-point Pulse Width Modulation (PWM) coupled to a gate of each switch.

Abstract: A circuit arrangement for automatic, load-dependent control of at least one winding current of a respective motor winding of a self-timed bipolar stepper motor, includes a first power driver circuit for a first motor winding and a second power driver circuit for a second motor winding. The circuit arrangement includes a first XOR gate and a second XOR gate, and a first resistor connected so as to couple the first XOR gate to an anode of a first diode. A cathode of the first diode is coupled to the comparator input of the first power driver circuit via a second resistor. A third resistor is connected so as to couple the second XOR gate to an anode of a second diode. A cathode of the second diode is coupled to the current-controlling comparator input of the second power driver circuit via a fourth resistor.

Abstract: The invention relates to a method for measuring a current that flows through a motor, in which a power switch that supplies the motor with electric energy is controlled by a control unit via a pulse width-modulation signal. The pulse width-modulation signal comprises a cycle of operation and the motor current is determined in a feeder to the power switch or a feeder to the motor. Since exactly one measured value representing the motor current is sampled in each cycle of operation, this permits the provision of a method for measuring the motor current, which determines the motor current in a more rapid, more cost-effective manner than in prior art. The method is used for the motor control of direct current motors.

Abstract: A medium voltage variable frequency drive having a 2-high controller configuration with a dual bus system is described. The drive control system includes at least one motor control cabinet housing a fused medium voltage bypass controller, a non-fused transfer controller positioned above the fused medium voltage bypass controller, an extendable output bus coupled to the non-fused medium voltage transfer controller, and an extendable supply bus coupled to the fused medium voltage bypass controller. The drive control system further includes a variable frequency drive cabinet housing a variable frequency drive. The variable frequency drive is coupled to the extendable output bus and a power supply line. The power supply line may be further coupled to the extendable supply bus. The drive control system includes at least one cabling transition cabinet housing cabling between the at least one motor control cabinet, the power supply line, and the variable frequency drive.

Abstract: The invention provides a method and a device for controlling an electric motor using pulse-width modulated control signals. Control pulses having a setpoint duty factor and temporally varying pulse widths and pulse spacing are generated in the process, the temporally varying pulse widths and pulse spacing being selected as a function of a load and/or thermal loading of the electric motor and/or its control device.

Abstract: A braking system for an aircraft provided with undercarriage, wherein an axial-flux reversible electric machine is set between the wheel and the frame of the undercarriage; current-dissipating resistors are provided, which can be connected to the windings of the axial-flux reversible electric machine during rotation of said wheel for dissipating by the Joule effect the induced currents generated by the axial-flux electric machine, which behaves as current generator, and producing a braking effect that slows down the movement of the wheel, thus exerting a braking action.

Abstract: An integrated fan drive system for a cooling tower comprising a high-torque, low speed permanent magnet motor having a rotatable shaft, a fan comprising a hub that is directly connected to the rotatable shaft and a plurality of fan blades that are attached to the hub, and a variable frequency drive device in electrical signal communication with the permanent magnet motor to control the rotational speed of the permanent magnet motor. The high-torque, permanent magnet motor comprises no more than two bearings in operative association with the shaft. The variable frequency drive device has a variable frequency controller that has an input for receiving AC power and an output for providing electrical signals that control the operational speed of high-torque, permanent magnet motor. The variable frequency drive device also includes a user interface in electronic data signal communication with the variable frequency controller to allow a user to input motor speed control data.

Abstract: A method of controlling a power converter in an electric drive machine is disclosed. The method may include determining a first switching frequency and determining a second switching frequency. The method may also include comparing the first switching frequency and the second switching frequency. The method may further include selecting a power converter switching frequency from the lesser of the first switching frequency and the second switching frequency to control a power converter.