A housing for an electronic circuit for a fuel pump includes a base and a cover which is connected to the base, a printed circuit board and, disposed on one side of the latter, electric and/or electronic components. Disposed on either side of the printed circuit board in each case is a cover in such a way that each component is arranged in a region covered by a cover.

A capacitor includes: an anode part that is drawn from an anode body of a capacitor element to an element end-face, to be formed over the element end-face; a cathode part that is drawn from a cathode body of the capacitor element to the element end-face, to be formed over the element end-face; an anode terminal member that is disposed in a sealing member; a cathode terminal member that is disposed in the sealing member; an anode current collector plate that is connected to the anode part, and is also connected to the anode terminal member; and a cathode current collector plate that is connected to the cathode part, and is also connected to the cathode terminal member.

A system for performing computing operations includes a rack, one or more shelves coupled to the rack, and two or more computing modules. Each computing module may include a chassis, one or more circuit board assemblies in a primarily vertical orientation, and one or more hard disk drives in a primarily vertical orientation. The circuit board assemblies and the hard disk drives are coupled to the chassis of the computing module.

The electronic component has a resin electrode which constitutes an external electrode on a face of a ceramic base body. At least a tip portion of a resin electrode region extended around another face of the body is bonded to the ceramic base body, and further a relationship between Rz1 and Rz2 satisfies the following requirement: Rz1>Rz2, Rz1>3.3 μm, and Rz2

The present invention is directed to a circuit interrupting device including an actuator that provides an actuator stimulus upon the occurrence of the fault actuation signal. A circuit interrupter is positioned to electrically disconnect the first, second and third electrical conductors from each other upon the occurrence of the actuator stimulus. An automated test circuit is coupled to the circuit interrupting assembly. The automated test circuit is configured to automatically produce the simulated fault condition during a predetermined portion of an AC line cycle to determine whether the fault detection assembly is operational such that the fault detection assembly provides a fault detection signal without the circuit interrupter electrically disconnecting the first, second and third electrical conductors from each other. The automated test circuit is further configured to provide a device failure mode signal such that a plurality of the first, second or third electrical conductors are disconnected from each other if the fault detection signal is not detected within a predetermined time frame.

Disclosed herein is a mounting structure of a circuit board having a multi-layered ceramic capacitor thereon. The mounting structure of a circuit board having a multi-layered ceramic capacitor thereon, in which a dielectric layer on which inner electrodes are disposed is stacked and external electrode terminals connecting the inner electrodes in parallel are disposed on both ends thereof, wherein the inner electrodes of the multi-layered ceramic capacitor and the circuit board are disposed so as to be a horizontal direction to connect the external electrode terminals with a land on the circuit board by a conductive material and a ratio of a bonding area ASOLEDER of the conductive material to the area AMLCC of the external electrode terminals AMLCC is set to be less than 1.4, thereby remarkably reducing the vibration noise.

An apparatus includes a case capable of receiving a plurality of capacitive elements, each capacitor element having at least two capacitors, and each capacitor having a capacitive value. The apparatus also includes a cover assembly with a peripheral edge secured to the case. The cover assembly includes, for each of the plurality of capacitive elements, a cover terminal that extends upwardly from the cover assembly generally at a central region of the cover assembly. Each cover terminal is connected to one of the at least two capacitors of the respective one of the plurality of capacitive elements. The cover assembly also includes, for each of the plurality of capacitive elements, a cover terminal that extends upwardly from the cover assembly at a position spaced apart from the cover terminal generally at the central region of the cover assembly.

A brake system and related components including a metering device are configured to regulate a control signal received from a brake control device such that a control valve delays the supply of a level of requested braking pressure for a prescribed amount of time. The metering device can be an inversion valve and orificed check valve in a control circuit adapted to allow relatively unrestricted flow until a threshold pressure is reached, after which pressure the inversion valve closes and the flow is metered through an orifice. This has the effect of allowing rapid brake actuation to a first level, and then slowing further application of the brake until full requested braking is achieved. An electronic control unit can also be configured to regulate a control signal to delay development of the requested brake pressure.

In some aspects, a master cylinder assembly for vertical lift aircraft is configured to move pressurized fluid through a conduit in response to applied movement of an input lever. A low pressure relief valve can be connected to a first conduit to limit pressure to a low level. An isolation valve can be connected to the first conduit and configured to isolate the low pressure relief valve from the conduit when engaged. A high pressure relief valve can be connected to a second fluid conduit to limit pressure to a high level. In some aspects, a rotor brake actuator is fluidly connected to the first conduit and the second conduit and configured to engage a rotor brake in response to hydraulic fluid pressure.

A method for operating a hydraulic brake system of a motor vehicle, comprising a pressure generating device used to build up additional brake pressure in a master brake cylinder or in addition to a master brake cylinder and in opposition to further pedal actuation wherein the additional pressure is a function of the pedal actuation travel distance. A method that reduces the limitations of a braking system's physical parameters on the build-up of additional braking pressure.

A brake control system for motor vehicles includes a stability system for stabilizing the vehicle from the standpoint of driving dynamics during braking, a triggering unit for the automatic output of a braking demand as a function of the traffic situation, a braking unit which converts the braking demand into a braking action, and a control unit for modifying the braking demand prior to its implementation as a function of the state of the stability system.

Methods and systems for a go/no-go Landing Decision Point (LDP) are disclosed. The methods and systems provide a graphical LDP on a cockpit display that pilots can use to determine whether to continue the landing or execute a go-around. The methods and systems may be implemented in embodiments having an onboard portion, an off-board portion, or both operatively coupled to provide an LDP in a preview/planning mode and real time mode.

A brake fade determination device determines whether a fade state of a brake device that brakes a wheel of a vehicle is occurring on the basis of the deceleration of the vehicle and the slip amount of the wheel. A braking system includes: the brake device that is able to adjust a braking force that acts on the wheel of the vehicle; and a controller that controls the braking force to control the slip condition of the wheel. The controller determines whether a fade state of the brake device is occurring on the basis of the deceleration of the vehicle and the slip amount of the wheel, and adjusts the amount of increase or decrease in braking force on the basis of whether the fade state is occurring.

A brake apparatus that can achieve front-rear distribution in accordance with a traveling environment variation. At an intermediate point from a start point of a second mode, first interval to an end point of a second mode, second interval, the increasing rate of braking force for a front wheel with respect to an operation amount is changed. The increasing rate of the operation amount prior to the intermediate point can be represented by a first inclination of a curve while the increasing rate of the operation amount after the intermediate point is represented by a second inclination of the curve. The first inclination is less than the second inclination. Setting the increasing rate after an intermediate point to be higher than the increasing rate before the intermediate point, the vehicle body generation deceleration can be caused to increase in a linear proportion to the operation amount.

Disclosed herein are a pre-fill system to improve brake feel and a method of increasing an initial flux using the same which may reduce an invalid travel distance of a brake pedal. The pre-fill system includes a first housing connected with the master cylinder and provided with a first bore having a smaller-diameter portion and a larger-diameter portion, a second housing provided with a stepped second bore communicating with the first bore to be coupled with the first housing to define a hydraulic pressure chamber, a piston arranged in the first bore and provided with an oil channel unit, and a valve assembly adapted to open and close the oil channel unit of the piston according to the hydraulic brake pressure, wherein the piston applies pressure to the hydraulic pressure chamber through the piston to supply hydraulic pressure to the disc brake.

An electronic control unit inputs from temperature sensors a temperature of the heating side of a thermoelectric conversion section assembled to each of brake units provided for left and right rear wheels. When the temperature of the heating side is equal to or lower than a predetermined temperature, the electronic control unit drives and controls a brake hydraulic pressure control section so as to operate the brake units preferentially over brake units provided for left and right front wheels. With this operation, each of the brake units generates friction heat, and heats the heating side of the corresponding thermoelectric conversion section, whereby the thermoelectric conversion section efficiently collects thermal energy and generates electrical power. Meanwhile, when the heating side temperature is higher than the predetermined temperature, the electronic control unit drives and controls the brake hydraulic pressure control section so as to decrease the proportion of the braking forces applied by the brake units and increase the proportion of the braking forces applied by the brake units.

A method in which the driving behavior of a vehicle is influenced as a function of data on the surroundings in order to assist an avoidance maneuver, as soon as a risk of a collision is detected on the basis of the data from one or more environment sensors, in particular radar sensors and/or cameras, and the data from one or more vehicle sensors, in particular a steering angle sensor and/or yaw rate sensor and/or wheel speed sensors, and the vehicle has an electronically controlled brake system which permits a driver-independent buildup and modulation of the braking forces at the individual wheels of the vehicle, wherein when a risk of a collision is detected, in a first phase a turning-in operation by the driver is assisted and/or in a second phase a steering operation by the driver is damped. Furthermore, an electronic control unit for a brake system is defined.

A method and system for diagnosing an operating status of an assisted start-up mode for a motor vehicle. The system includes a driving engine, a transmission including a mechanism determining a piece of engine rotation speed information, a piece of information on a position of an accelerator pedal of the vehicle, a piece of information on a position of a transmission, and a piece of information on torque transmitted to wheels, a detection mechanism producing a malfunction signal for the assisted start-up using the information received, a plurality of encoding mechanisms to produce a follow-up signal for each piece of calculated information received, and a memory saving the follow-up signals.

A brake system for a motor vehicle includes on at least one wheel, an electric-regenerative brake and a friction brake that can be hydraulically actuated by a first generator of brake pressure using a fluid, wherein the friction brake can be connected via an actuatable inlet valve to the first generator of brake pressure and via a first actuatable outlet valve to a pressure accumulator, so that a volume of fluid applied by the first generator of brake pressure can be diverted via the first outlet valve into the pressure accumulator. The first generator of brake pressure can be connected to the pressure accumulator via a further hydraulic connection having a second actuatable outlet valve. A method for operating a brake system is also disclosed.

An electric-hydraulic antilock braking system (ABS) installed in a trailer is coupled with a tow vehicle to facilitate controlled braking of the trailer. A trailer in-cab controller (TIC) monitors vehicle networks for diagnostic information used in determining appropriate braking actions to be taken. A communication network can interconnect the TIC, a trailer actuator controller (TAC), and an ABS controller. The ABS controller receives current tow vehicle speeds and current trailer wheel speeds, and dynamically adjusts the brakes based on the differences in the speeds. A three-way solenoid valve or an equivalent valve structure thereto allows for the ABS system to be quickly activated and deactivated.

An electric braking device for a vehicle. The device includes: front wheel and/or rear wheel braking modules that are not powered when the vehicle is in a standby state; at least one on-board computer; at least one user control module which, upon a user's request, delivers a power supply control signal to control the power supply to the braking modules and braking control signals to activate the braking modules when the modules are powered; and a mechanism for cutting the power supply to the braking modules once the vehicle has zero speed and the wheels are immobilized under action of the braking modules. The device can reduce the power consumption of vehicles.

A system and method for brake assisted turning are provided. One system includes a pedal operated braking system configured to apply hydraulic brake pressure to brakes of a vehicle when one or more brake pedals are pressed. The system also includes a steer assist braking system configured to apply hydraulic brake pressure to the brakes of the vehicle based at least partly on a steering angle. The system includes hydraulic shut-off circuitry configured to selectively enable and disable operation of the steer assist braking system.

A braking system for a vehicle, particularly a commercial vehicle, includes an operating brake device for providing an operating brake function for braking the vehicle, and a parking brake device for providing a parking brake function independently of the operating brake system. If one of the two braking devices partially or completely fails, the vehicle can be braked automatically by means of the other braking device.

In a pump housing of a motor-vehicle hydraulic assembly, on which at least two inlet-valve openings, at least two outlet-valve openings, at least one high-pressure control valve opening and at least one switchover-valve opening and a pressure-sensor connection are formed. The at least two inlet-valve openings are arranged in a first row, the at least two outlet-valve openings are arranged in a following second row, the pressure sensor connection is arranged in a further following third row, and the at least one high-pressure control valve opening and the at least one switchover valve opening are arranged in a further following fourth row. There are also five embodiments of arrangements of connecting lines and holes in a pump housing for the short connection of the valve openings and connections, and one embodiment with respect to the use of the pump housing according to one of the six embodiments.

When a trailer is pulled by a tow vehicle where the trailer begins to sway to the left and right of the tow vehicle a large sway can result in loss of control of the trailer and or tow vehicle. The field of the present invention is a system and method of controlling a trailer sway which comprises determining the sway of the trailer utilizing an electronic sensor and independently applying the left and or right trailer brakes at varying levels to reduce trailer sway the traditional single braking signal power from the tow vehicle is separated into two independent braking signals for each of the left and right brakes. All brakes are applied whenever the traditional braking signal goes active where trailer battery power is utilized to independently activate the left and or right brakes during trailer sway.

A method is provided for operating a parking brake module that is at least partially integrated into a compressed air generation system in the event of defects, having a control unit, solenoid valves, and a relay valve for aerating and deaerating at least one spring-loaded brake cylinder. A pressure in the parking brake module which is elevated compared to a normal pressure is determined. A constant compressed air delivery is stopped. A reduced switch-off pressure of the compressed air generation system is set. The pressure level in the parking brake module is lowered to the reduced switch-off pressure through repeated activation of the relay valve.

A system for electrical braking of a vehicle comprises a power bus coupled to a first driver associated with a first electromechanical actuator (EMA). The power bus is also coupled to a second driver associated with a second EMA, and the first EMA and the second EMA are associated with a wheel of the vehicle. The power bus provides braking power to the first EMA via the first driver and to the second EMA via the second driver. A normal braking command interface provides a first braking signal to the first driver and a second braking signal to the second driver. An emergency/park brake interface bypasses the normal braking command interface and sends a first emergency/park braking signal to the first driver and a second emergency/park braking signal to the second driver. A sensor measures a current at a single location of the power bus that is proportional to a braking force exerted on the wheel.

Disclosed is a method for operating an electromechanically operable parking brake for motor vehicles with a driving engine furnished with a mechanical gear box, being substantially composed of an operating element, an electronic control unit, to which are sent wheel rotational speed values from wheel rotational speed sensors, at least one unit for generating a brake application force, and brake devices on at least one axle being lockable by the unit, with the electronic control unit actuating the unit after detection of a starting maneuver of the motor vehicle in the sense of a release operation of the parking brake. In order to render a release operation of the parking brake as comfortable as possible after detection of a starting maneuver of the motor vehicle, the method at issued arranges that the electronic control unit (6) actuates the unit (1) in order to reduce the brake application force to an inclination-responsive holding force when a starting maneuver is detected and before the release operation of the parking brake is performed.

An electric driving type utility vehicle having a regenerative brake force distribution control function, and a regenerative brake force distribution control method thereof are provided. The utility vehicle includes: a controller for controlling an output and a recovery of a motor; recovery sensing means for sensing a recovery braking state when the motor is driven; a power measurement unit for measuring the amount of recovery power generated in the recovery braking state; and a power switching unit for automatically switching a drive mode from a two-wheel drive mode to a four-wheel drive mode or vice versa according to the load condition. The present invention can switch the present mode to the four-wheel drive mode by operating the power switching unit according to the control of the controller when sensing the recovery brake through the recovery sensing means in the driving state.

A method for hydraulically boosting a vehicle electric parking brake having a hydraulic service brake and an electric parking brake. Application forces electically generated by the parking brake function is superimposed on the boosting brake force generated by a hydraulic boosting brake pressure provided by the service brake to the brake actuator. When the parking brake is actuated to generate a predetermined application force, the force generated by the brake actuator is detected as the actual value, if an actual value of the measured value is smaller than a first target value a boosting brake pressure value is applied to the brake actuator, and by means of the parking brake function an adjustment function for the tension of the brake actuator to which the hydraulic boosting brake pressure is applied is carried out to achieve the predetermined application force.

A control device for a braking system of a vehicle is provided, having a first receiving device which receives a provided brake activation intensity variable, a plunger control device which determines a setpoint fill level variable of a plunger, taking into account at least the received brake activation intensity variable, and a corresponding plunger control signal is outputtable so that a ratio of an actual volume and a maximum fillable volume of a storage volume of the plunger is settable corresponding to the determined setpoint fill level variable. For a brake activation intensity variable corresponding to a predefined non-activation intensity variable, the plunger control device determines a fill level variable different from an empty state as the setpoint fill level variable, and outputs a plunger control signal corresponding to the determined setpoint fill level variable to the plunger such that the plunger is at least partially filled.

Disclosed is a control method of an electronic parking brake system, which variably controls the duty of voltage applied to a motor upon release of the electronic parking brake system. The control method includes controlling voltage applied to a motor to a first duty ratio upon release of the electronic parking brake system, controlling the voltage applied to the motor to a second duty ratio greater than the first duty ratio if locking of the motor occurs and the motor is not operated, and controlling the voltage applied to the motor to the first duty ratio if locking of the motor is released and the motor begins to operate, after the control of voltage to the second duty ratio.

Systems and methods disclosed herein may be useful emergency braking systems for use in, for example, an aircraft. A system is disclosed that allows emergency braking without the need for a manually operated emergency brake. For example, a system is provided comprising a potentiometer in mechanical communication with a brake pedal, a first electronic switch in electrical communication with the potentiometer, a second electronic switch indicating a displacement of the brake pedal, wherein a brake control valve opens in response to the first electronic switch, and wherein a shutoff valve opens in response to the second electronic switch.

A pressure control valve arrangement for controlling a fluid pressure in an ABS brake system of a vehicle so that, while there is a tendency of individual wheels of the vehicle to lock, the brake pressure in at least one associated brake cylinder can be adaptively adjusted, including: a housing; and at least one diaphragm valve is accommodated in the housing, the diaphragm valve having a diaphragm as the valve body, which diaphragm can be acted upon by introducing pressure medium into a control chamber that is covered on the outside of the housing by a cover so that the control chamber is formed between the diaphragm and the cover, wherein at least one pressure medium channel carrying pressure medium is formed in the housing in the region of the cover, wherein at least one cover has at least one projection projecting into the pressure medium channel in the housing, a pressure medium guiding surface for directing the flow of the pressure medium carried in the pressure medium channel being formed on the projection.

A flat, box-shaped hydraulic block for the mechanical fastening and hydraulic interconnection of solenoid valves, pump elements, etc. of a slip-controlled vehicle brake system connects connections of installation spaces for the pump elements to connectors for a brake master cylinder and connections of receptacles for pressure build-up valves which run past one another via flat chambers on longitudinal sides of the hydraulic block and short blind bores. As a result, the receptacles of the pressure build-up valves are connected to the connectors for the brake master cylinder. The chambers damp pressure pulses of the pump elements of a piston pump.

A method of controlling a vehicle having a transmission system, an engine system, and a braking system includes detecting a braking condition of the braking system. The braking condition is at least one of a brake temperature being above a predetermined brake temperature limit and a braking load being above a predetermined braking load limit. The method also includes detecting a second condition of at least one of the transmission system and the engine system. The method also includes determining whether the second condition satisfies predetermined criteria. Furthermore, the method includes detecting an absolute vehicle acceleration that is below a predetermined acceleration limit. Moreover, the method includes downshifting from a current gear to a lower gear to thereby cause engine braking when the braking condition is satisfied, the second condition satisfies the predetermined criteria, and the absolute vehicle acceleration is below the predetermined acceleration limit.

A method and a device for controlling and/or regulating an electric motor. Such electric motors are used for example in motor vehicles in the form of pump motors. In general, the electric motor is supplied with electrical energy from a battery and/or using a generator. The controlling and regulation take place using a high-frequency pulse width modulation (PWM). When the electric motor is started, the PWM is used to continuously increase the motor current required for the operation of the electric motor, e.g. beginning from 0.

A variable speed power converter controls the speed of a load in a material handling system as a function of the torque required to move the load. While the power converter is running, the torque being produced in the motor is determined. The power converter then determines the maximum rotational speed of the motor as a function of the torque currently being produced and of the torque-speed curve of the motor. The power converter then commands the motor to rotate at this maximum rotational speed. The power converter periodically monitors the torque being produced and adjusts the maximum rotational speed of the motor throughout the run.

To achieve peak acoustic and power performance, the coil or applied current should be in phase or substantially aligned with the back electromotive force (back-EMF) voltage. However, there are generally phase differences between the applied current and back-EMF voltage that are induced by the impedance of the brushless DC motor (which can vary based on conditions, such as temperature and motor speed). Traditionally, compensation for these phase differences was provided manually and on an as-needed basis. Here, however, a system and method are provided that automatically perform a commutation advance by incrementally adjusting a drive signal over successive commutation cycles when the applied current and back-EMF voltage are misaligned.

A driving system for a fan that enables an increase in motor current that may be supplied to excitation windings at the time of a maximum static pressure without increasing the rotational speed excessively when an amount of maximum air flow is provided. The fan driving system includes a drive signal generating circuit that generates drive signals, a motor driving circuit that supplies a motor current to the motor in accordance with the drive signals, a current detecting circuit (resistance) that detects the motor current, and a drive signal changing circuit. The drive signal changing circuit changes the drive signals generated by the drive signal generating circuit to restrict an increase in the motor current when the motor current becomes larger than a threshold.

A motor control apparatus for controlling a DC motor includes a first detection unit configured to detect an angular velocity of the DC motor, a driven member configured to be driven by the DC motor, a control unit configured to perform, during start-up of the DC motor, feed forward control for changing a control value used for controlling drive of the DC motor from a first control value corresponding to an angular velocity smaller than a target angular velocity to a second control value corresponding to the target angular velocity, and to change the feed forward control to feedback control for controlling the control value based on a detection result by the first detection unit to keep the DC motor at the target angular velocity, and a second detection unit configured to detect whether the driven member has been replaced.

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.

Electromotive furniture-flap drive, characterized by an identification device for automatically identifying the type of furniture flap in the installed state of the furniture flap drive.

A system and method for determining the start position of a motor. According to an embodiment, a voltage pulse signal may be generated across a pair of windings in a motor. A current response signal will be generated and based upon the position of the motor, the response signal will be greater in one pulse signal polarity as opposed to an opposite pulse signal polarity. The response signal may be compared for s specific duration of time or until a specific integration threshold has been reached. Further, the response signal may be converted into a digital signal such that a sigma-delta circuit may smooth out glitches more easily. In this manner, the position of the motor may be determined to within 60 electrical degrees during a startup.

A control circuit for a blender provides low-cost power conditioning through the use of a high resistance which provides temporary power for operation of low-voltage logic circuitry and low-voltage switches for a time sufficient to switch the motor on, and a lower resistance which provides sufficient power for maintaining the motor on state indefinitely as instructed by the low-voltage logic circuitry. Low average power dissipation is provided by powering the low-voltage logic circuitry and low-voltage switches using the high resistance in a standby mode and switching in the lower resistance only when the motor is activated.

A circuit for speed monitoring of an electric motor comprises a circuit for generating a time-frame signal, a circuit for receiving a first signal from a chopper driver circuit designed to drive the electric motor, a circuit for detecting chopper pulses in the first signal, a pulse counter, and a circuit for at least one of outputting and evaluating a state of the pulse counter, after the inactive state of the time-frame has been indicated. The time-frame signal indicates when a time-frame of predefined length changes from an inactive state to an active state and indicates when the time-frame changes back from the active state to the inactive state. The pulse counter is designed to count the detected chopper pulses while the active state is indicated by the circuit for generating the time-frame signal.

In order to process a motor signal (Ia, Um) of a DC motor (4), in particular of an adjustment drive of a motor vehicle, the armature current (Ia) and the motor voltage (Um) of the DC motor (4) are detected and used for determining the back-emf (E) of the DC motor (4), wherein the determined back-emf (E) is used to generate a useful signal (Sf, SEFL), which is in particular speed-proportional, from the armature current signal (Ia) for position sensing or for evaluating an excess force limitation.

A method and device for controlling an electric motor, in particular a machine tool drive, wherein during a sensorless open-loop control mode of operation of the electric motor the speed and the torque are determined from the motor current and the motor voltage, and the moment of inertia of the electric motor torque are determined from the determined motor current and the determined motor voltage, wherefrom then a control torque is determined, which is then associated with an open-loop torque control value and supplied as the torque setpoint value to a control element for setting the motor current and/or the motor voltage in the open-loop mode of operation. As long as the speed is below a minimum speed, the control element receives as input variable a control or pilot control torque generated from a predefined moment of inertia for a sensorless closed-loop control mode of operation of the electric motor.

A computer-implemented fan control method includes measuring a temperature within a computer system and dynamically selecting a fan speed step in response to the temperature received, wherein the fan speed step is selected from a fan speed table defining a finite number of fan speed steps each having an associated fan speed. A fan is operated at the dynamically selected fan speed step, wherein the fan is positioned to drive air through the computer system where the temperature is being measured. The fan output variation is measured over a prescribed time interval and the fan speed table is automatically modified to change the fan speeds associated with each fan speed step, wherein the fan speeds are changed as a function of the measured fan output variation while continuing to drive the fan.

A voltage regulator for a pair of electric motors has an input for a signal indicative of the desired speed for the motors and a pulse width modulation control circuit device. A control module provides a conditioning signal to the control circuit to output to the motors a square wave voltage having a duty-cycle which varies according to a predetermined function of the signal applied to the input of the regulator. The control circuit device has first and second electronic solid state switches associated with the motor and controlled by the control module.