23942results about "AC motor control" patented technology

A control console to remotely control medical equipment is disclosed having a base with an ergonomically adjustable pedal system. The base further has an opening to receive the pedal system. The pedal system includes a moveable pedal tray with a pedal base. The tray includes a first left pedal assembly and a first right pedal assembly, and an upper tier having a second left pedal assembly and a second right pedal assembly respectively in alignment with and elevated above the first left pedal assembly and the first right pedal assembly. Rollers are rotatable coupled to the moveable pedal tray to allow it roll over a floor. A drive assembly is coupled between the moveable pedal tray and the base. The drive assembly applies a force to the to roll the moveable pedal tray over the floor within the opening of the base.

An apparatus for controlling the speed of an AC motor comprising a switch adapted to be coupled in parallel with power terminals for the AC motor; a capacitor coupled in series with the parallel combination of the switch and the motor; the capacitor adapted to provide an AC supply voltage from an AC source to the parallel circuit comprising the motor and the switch; and a control circuit for controlling the conduction time of the switch in order to vary the speed of the motor. The switch is preferably pulse-width modulated at a frequency twice the line frequency of the AC supply voltage, and the switch is turned on when the voltage across the AC motor is zero volts. The apparatus is operable to provide for continuously variable control of the motor speed while minimizing acoustic noise in the motor.

A motor control device selectively turns on or off a drive transistor in-accordance with a PWM control signal Sp, such that a drive current Im supplied to a motor is adjusted. The device also samples and holds a motor current Sm for obtaining a motor current value Ih. With reference to the motor current value Ih, the device protects the motor from an overcurrent. Sampling and holding of the motor current Sm is performed for a sampling and holding time Ts. The sampling and holding time Ts corresponds to a time period between a first point in time when the level of the PWM control signal Sp is switched for turning off the drive transistor and a second point in time that precedes the first point in time by a predetermined period. As a result, the motor current value Ih is detected with high accuracy.

A controllable motor includes a rotor. A first stator winding set is operable, upon being energized, to generate and apply a first torque to the rotor. A second stator winding set independent of the first stator winding set is operable, upon being energized, to generate and apply a second torque to the rotor. A motor control is coupled to the first and second stator winding sets. The motor control is operable to selectively energize one of the first or second stator winding sets to thereby generate and apply one of the first or second torques to the rotor, and simultaneously energize both the first and second stator winding sets to thereby generate and apply a third torque greater than the first or the second torque.

An H-bridge circuit is connected to a coil of the vibration motor that is to be driven. A comparator receives Hall signals indicating position information of a rotor of the vibration motor, and converts to an FG signal. A pulse width modulator generates a pulse-modulated pulse signal specifying energization time of the coil of the vibration motor. The pulse width modulator, in a first mode, after commencing start-up of the vibration motor, sets a duty ratio of the pulse signal to 100%, and after that, switches the duty ratio to a predetermined value in accordance with rotational frequency of the motor. In a second mode, the duty ratio of the pulse signal continues to be set to 100%. In a third mode, frequency and the duty ratio of the pulse signal are set based on a control signal of a pulse form inputted from outside. The control signal is used also in switching mode.

A motor driving method for driving a direct-current (DC) motor, designed for avoiding a reverse current induced by the Back Electromotive Force (BEMF), includes providing a driver circuit for driving the DC motor; comparing a signal level of a terminal of the DC motor and a predetermined voltage value to produce a comparing result; and controlling a specific lower gate switch to avoid the occurrence of a reverse current of the DC motor according to the comparing result.

An apparatus and method for controlling a hybrid motor, The hybrid motor, uses a permanent magnet instead of a field coil for a rotor, winds a coil round a stator in a multi-phase independent parallel manner, fixes a rectifying type encoder to the rotor and connects a sensor to a driving circuit. The apparatus comprises: an encoder attached to a rotor in cooperation with a pole sensor a speed input unit for generating a speed instruction signal a power switching circuit to generate motor driving signals; a drive module receiving the speed instruction signal and the sensor signal and outputting the speed instruction signal synchronized with the sensor signal as a driving motor signal; a power supply for applying a DC voltage to the power switching circuit; A logic power supply for converting the DC voltage into a logic voltage, and applying logic voltage to the drive module. The motor has n phases, n power switching circuits and n drive modules.

For the present invention, under various running speeds statuses, the voltage supplied to the DC brushless motor is relatively increased or decreased on the basis of the internal setting of the motor drive control device according to the increased or decreased rotational output speed, so as to prevent the shortcoming of too much variation of the input impedance caused by the inductive reactance of the winding accordingly changed when the speed of the DC brushless motor is changed, specifically, to prevent the shortcoming of unable producing required torque resulting from the increased inductive reactance caused by increasing the rotational speed which makes the current value become too low when input by the original working voltage.

The invention provides a forward and reverse motor for improving forward and reverse efficiency, and a control method thereof. By adopting the forward and reverse motor having a first winding and a second winding and a third winding both having the phase differences differing for 90 degrees of that of the first winding, and a switching circuit, the switching circuit connects the first winding as the main winding and the second winding as the secondary winding to the working circuit of the motor, or connects the third winding as the main winding and the first winding as the secondary winding tothe working circuit of the motor, thereby ensuring that the parameters of the number of turns, wire diameters and resistances of the main winding and the secondary winding in each case can be separately designed when the motor rotates forwards or reversely to ensure high efficiency of the motor in both forward and reverse rotations, which solves the problem that the forward and reverse motor cannot reach high efficiency in forward and reverse directions in the related art.

An inverter device includes a plurality of switching circuits in which first switching elements including Si semiconductors and second switching element including WBG semiconductors having ON resistance smaller than that of the first switching elements and having switching speed higher than that of the first switching elements are connected in parallel. The inverter device includes a converting circuit that converts a direct-current voltage into a desired alternating-current voltage and a driving unit that generates a plurality of driving signals for respectively turning on and off the switching circuits. The inverter device includes, for each of the switching circuits, a gate circuit that, based on the driving signals, turns on the second switching element later than the first switching element and turns off the first switching element later than the second switching element.

A driving controlling apparatus for a linear compressor, comprises: a storing unit for storing a reference phase difference to judge an overload state; and a controlling unit for judging an overload state based on a comparison result between the reference phase difference and a phase difference between a current and a stroke, and controlling a voltage or a current applied to a linear motor based on the judgement result.

A photovoltaic inverter control method includes steps of monitoring a variation in output voltage of a solar battery by a power and voltage monitoring circuit (51) and, when the variation occurs, accelerating or decelerating an electric motor (3) to maximize the output voltage of the solar battery (1), whereby the electric motor for driving, for example, a pump and a fan by the solar battery as a power source can be driven by a photovoltaic inverter always at the maximum power point of the solar battery.

A system for hydraulically fracturing an underground formation in an oil or gas well to extract oil or gas from the formation, the oil or gas well having a wellbore that permits passage of fluid from the wellbore into the formation. The system includes a plurality of electric pumps fluidly connected to the well, and configured to pump fluid into the wellbore at high pressure so that the fluid passes from the wellbore into the and fractures the formation. The system can also include a plurality of natural gas powered generators electrically connected to the plurality of electric pumps to provide electrical power to the pumps.