132results about "Slip frequency motor control" patented technology

A system and method are provided for reducing the energy consumed by a pump jack electric motor by reducing the supply voltage to the motor when the motor would be generating energy in open loop mode. By substantially eliminating the energy generation mode, the braking action of the utility grid in limiting the acceleration of the motor and system that would otherwise occur is substantially removed. The motor and system will speed up, allowing the natural kinetic energy of the cyclic motion to perform part of the pumping action. A closed loop controller in electrical connection with the motor computes the necessary information from the observed phase angle between the voltage and current supplied to the motor. By reducing the supply voltage to the motor, the observed phase angle may be reduced to a target phase angle value. By allowing some current flow, primarily of a reactive nature, an observable feedback parameter may be used in the closed loop control system as an indication of the load condition, to which the closed loop motor controller may react, supplying power when needed, such as in the energy consumption mode. The electric motor may be effectively turned off, but without completely cutting the power to the motor. During both the energy consumption mode and the period that open loop energy generation would be occurring, the closed loop motor controller may reduce the observed phase angle to a target phase angle by reducing the supply voltage. Any further reduction in the observed phase angle below the target phase angle may be interpreted as an increase in motor load, to which the motor controller may respond by increasing the supply voltage to the motor until the target phase angle is once again reached.

This disclosure relates to transient energy systems for supplying power to a load substantially instantaneously on demand. Transient energy systems may include a flywheel coupled the rotor of an induction motor generator. One embodiment of the disclosure refers to systems and methods for reducing loads on a bearing in a transient energy system. In another embodiment, the disclosure refers to an induction motor generator that is optimized for high power transient power generation, yet low power motor operation. Yet another embodiment of the disclosure refers to using a flywheel as a drag pump to cool components of a transient energy system. In yet another embodiment, a slip control scheme is discussed for regulating a DC bus. In yet a further embodiment of the disclosure a method is provided for reducing unnecessary turbine starts by making turbine start a function of the rotational velocity of a flywheel.

A system and method for providing constant-frequency electrical power from variable-speed mechanical power are disclosed. The system includes a wound-rotor induction machine generator (WRIMG), a first power converter, e.g., an inverter or a bridge rectifier, that provides power from the stator assembly of the WRIMG to the load, and a second power converter, e.g., an inverter or a bridge rectifier, that provides power from the rotor assembly of the WRIMG to the load. A controller controls the output stator-current based on comparisons between measured DC load bus data and a reference DC load bus voltage value, measured machine shaft angular position and reference rotor frequency data, and measured stator-current data that is fed-back to the stator-current controller by the power converter device(s).

Provided are a method for compensating instantaneous power failure in medium voltage inverter and a medium voltage inverter system by using the same, the method for compensating instantaneous power failure in medium voltage inverter including a plurality of power cells supplying a phase voltage to a motor by being connected to the motor in series, the method including decreasing an output frequency of the plurality of power cells by as much as a predetermined value at a relevant point where an input voltage of the plurality of power cells is less than a reference value, decreasing the output frequency at a predetermined deceleration gradient, and maintaining the output frequency during restoration of input voltage as long as a predetermined time, in a case the input voltage is restored.

A motor controller (4) and method for maximizing the energy savings in an AC induction motor (3) at every load wherein the motor is calibrated at two or more load points to establish a control line (6), which is then programmed into a non-volatile memory (30) of the motor controller. A DSP-based closed-loop motor controller observes the motor parameters of the motor such as firing angle/duty cycles (23), voltage (37), current (9) and phase angles to arrive at a minimum voltage necessary to operate the motor at any load along the control line. The motor controller performs closed-loop control to keep the motor running at a computed target control point, such that maximum energy savings are realized by reducing voltage through pulse width modulation.

An induction motor drive system and method estimates a motor power factor based on the AC power output to the motor phase windings and estimates the rotor speed based on the estimated power factor. The estimated rotor speed is compared to a rotor speed command signal to generate a speed error, and the voltage and frequency input to the motor are adjusted in response to the speed error. Rotor speed is estimated based on estimated rotor slip, which is estimated based on the applied voltage, frequency, estimated power factor and estimated motor power.

The operation of an AC induction motor 24 is controlled in response to the actual slip exhibited by the motor during operation. The slip of the motor 24 may be determined by determining the actual running speed, n, of the motor shaft 25A, measuring the line frequency, n_s, of the electricity supplied to the motor, and calculating the slip, S, of the motor using the relationship: S=((n_s−n)/n_s)*100. If the slip is too high when compared to a predetermined maximum acceptable slip, corrective action is taken to decrease the loading on the motor. If the slip is too low when compared to a predetermined minimum acceptable slip, corrective action is taken to increase the loading on the motor. By adjusting the operation of the system by appropriately changing the load on the motor, or changing the electrical supply parameters, the actual slip exhibited by the motor 24 is returned to a value within the range between the minimum acceptable slip and the maximum acceptable slip, thereby protecting the motor and improving overall reliability.

Methods and systems are provided for producing a commanded torque in an electric motor in a vehicle. A method comprises obtaining a torque command, obtaining a speed of the electric motor, and operating the inverter based at least in part on a voltage command that corresponds to minimal current through the electric motor for producing the commanded torque at the instantaneous speed of the electric motor.

There is provided a current tracking PWM control circuit that directly generates PWM signals such that inverter output currents id, iq track PWM current references id**, iq**, using the results of comparison of the inverter output currents id, iq and PWM current references id**, iq**, in which, if current references id*, iq* exist, the result of adding the original current reference iq* and a correction signal iqC*, obtained by amplifying the deviation (iq*-iq) of the current reference iq* and iq, is used as the PWM current reference iq** on the q axis side for performing current control, but, in respect of the d axis side, the original current reference id* is used directly as the PWM current reference id** for performing current control.

An electrical submersible pumping (ESP) system can include a pump located in a wellbore, a motor attached to the pump, a power source located at the surface, a cable electrically coupling the power source and the motor, and a current sensor. The ESP system can also include a controller communicating with the current sensor to calculate a voltage drop associated with the cable responsive to an impedance of the cable. The controller can also control a power source output voltage responsive to the calculated voltage drop. For example, the controller can adjust the power source output voltage to minimize a cable current while maintaining a minimum motor voltage. The controller can also control a motor shaft speed by changing a power source output voltage frequency to compensate for changing slip and adjust the power source output voltage to minimize the cable current while maintaining a minimum motor voltage.

The invention discloses a position-sensor-free speed regulating control method for a brushless doubly-fed motor. The method includes the steps of acquiring a frequency fp of a power winding; acquiring a frequency fc of a control winding; acquiring a rotating speed identification value according to the frequency fp of the power winding and the frequency fc of the control winding; subtracting the rotating speed identification value from a rotating speed instruction value to acquire rotating speed deviation, and acquiring a control winding current amplitude instruction value after the rotating speed deviation is subjected to PI (proportional-integral) regulation; acquiring a power factor angle of the power winding, subtracting the power factor angle from a power factor angle instruction value to acquire power factor angle deviation, and acquiring a control winding current frequency instruction value after the power factor angle deviation is subjected to PI regulation; performing current closed-loop control on the control winding according to the control winding current amplitude instruction value, the control winding current frequency instruction value and an actual sampling value of control winding current, so that an actual response value of the control winding current tracks the instruction value of the current. The position-sensor-free speed regulating control method for the brushless doubly-fed motor does not depend on a position sensor, so that a series of problems caused by position sensor mounting are avoided; cost is reduced.

A system to control an asynchronous tri-phase motor where said system comprises: at least one filter directly coupled to the current of the Alternative Current (AC) line; a rectifier which rectifies the line current, a doubler which reduces the curl, elevates the voltage and delivers a voltage in Direct Current, a braking resistance which helps to dissipate energy when the system is in braking mode, a shunt resistance, which helps to measure the current which flows from the V-line between the doubler and the IGBT module, a source, which adapts the voltage which the microcontroller consumes and peripheries (operational amplifiers, detectors, etc.), a line regulator to remove curls and line noise, a microcontroller to process, admit and emit control signals, a potential module which emits a PWM train pulse with a frequency determined by the microcontroller towards the IGBT module when the microcontroller indicates such, an IGBT module, which receives the PWM pulse train adapting and coupling them to an H bridge, to thus allow the flow of high voltage in DC emanating from the doubler towards the electric motor, a retro-feeding line towards the microcontroller to measure current, a velocity detector coupled mechanically to the motor and which sends a signal or pulse train towards the microcontroller; as well as the acceleration or braking methods consistent in the measurement of the slip S of said tri-phase motor.

The invention provides a vector control apparatus and a motor control system, comprising a alternating voltage generating unit that resolves alternating voltage with frequency different from that of motor current into magnetic-excitation axis voltage component and torque axis voltage component and performs superposition; a high-frequency-current phase difference computing unit that computes phase difference between high-frequency current and alternating voltage Vdh*, Vqh* by subtracting phase (arctan (Delta Iqc/Delta Idc), or arctan (Delta Ibc/Delta Iac))of superimposing axis from phase of high-frequency current generated in motor current by alternating voltage; a superimposing axis adjusting unit that adjusts phase direction of superimposing axis such that phase difference computed by high-frequency-current phase difference computing unit becomes zero; an axis deviation amount computing unit that computes axis deviation amount between superimposing axis whose direction has been adjusted by superimposing adjusting unit and magnetic-excitation axis; and a magnetic-excitation axis adjusting unit that adjusts phase direction of magnetic-excitation axis such that axis deviation amount becomes zero.

An object of the present invention is to provide a driver for an induction motor which performs an operation at an acceleration suitable for the magnitude of a load and is excellent in efficiency, without an acceleration failure.

The driver for an induction motor includes a slip frequency estimate value arithmetic operation section 15 for arithmetically operating a slip frequency ωŝ of an induction motor 12, and a maximum torque generation slip arithmetic operation section 16 for arithmetically operating a slip frequency ωsmax at which a maximum torque is generated. When the slip frequency ωŝ exceeds a predetermined value ωsmaxTH(=0.96ωsmax, etc.) corresponding to the slip frequency ωsmax at which the maximum torque is generated, a speed change rate arithmetic operation section 17 and a speed change rate correcting section 18 reduce a rate of increase in a speed command ωr*.

In addition, when the slip frequency approaches the maximum torque generation slip frequency too closely, the load concerned is judged to be overloaded, and an alarm is generated.

The embodiment of the invention discloses an asynchronous oscillation suppression method of an separately controlled doubly fed electric machine and a doubly fed electric machine system of the asynchronous oscillation suppression method. The method comprises the steps that active power of a rotor of the electric machine is calculated; an oscillating component of the active power is extracted from the active power; a slip frequency compensation quantity is calculated according to the oscillating component; slip frequency of the electric machine is compensated through the slip frequency compensation quantity. According to the asynchronous oscillation suppression method of the separately controlled doubly fed electric machine and the doubly fed electric machine system of the asynchronous oscillation suppression method, the slip frequency compensation quantity of the electric machine is calculated according to the oscillating component of the active power of the rotor and used for conducting compensation on the slip frequency, system damping is increased, stability of the system and rapidity of a response are improved, and the inherent unstable problems such as out-of-step which is prone to occurrence and overcurrent of a separately controlled doubly fed speed regulating system are solved.

The present invention relates to an asynchronous machine control method based on linkage compensation. The method comprises: the step 1, calculating a motor torque and an air gap linkage amplitude value; the step 2, respectively obtaining a slip frequency given value and a voltage compensation value after amplitude limiting; the step 3, obtaining a basic output voltage given value of an inverter on a V/F curve according to the output frequency given value of the inverter; the step 4, calculating the output voltage given value of the inverter; and the step 5, controlling the switching state of an IGBT through a modulation unit through the inverter, and outputting the output voltage given value and the frequency given value to a motor. The asynchronous machine control method based on linkage compensation employs a flux linkage amplitude regulator to combine a V/F control curve to greatly improve a motor output torque response speed; the flux linkage amplitude regulator uses a flux linkage amplitude value and does not use a decoupled flux linkage amplitude value in a vector control mode so as to greatly reduce the dependence on the motor parameters and improve the control performance; and moreover, the asynchronous machine control method based on linkage compensation employs a torque regulator to combine the motor rotation speed to realize motor slip control and reduce the motor output torque fluctuation.

A control device includes a slip calculator that calculates a first slip frequency of an induction motor, a current detector that detects motor current that passes through the induction motor, an adder that calculates a primary frequency by adding a speed command and a second slip frequency that are given, a command voltage generation unit that generates first command voltage from the primary frequency, a voltage error observer unit that estimates a command voltage error from the first command voltage and the motor current, a slip correction unit that calculates a slip correction amount from the command voltage error, an adder that calculates the second slip frequency by adding the first slip frequency and the slip correction amount, and a voltage error correction unit that corrects the first command voltage using the command voltage error and outputs second command voltage.

The invention relates to an automatic quasi-synchronization grid-connected control method for automatic-control frequency conversion soft start of medium-high pressure synchronous motors, and aims to solve the problem that the phase angle slip frequency is unstable due to the fact that the speed ring PI algorithm is adopted to cause irregular fluctuation of rotating speed in a dual-closed-loop speed regulating system when a current inner ring has nonlinear dead zone factors. A self-adaptive composite speed control method is adopted, and a speed control algorithm of a single proportional component having the self-adaptive function in the speed rising phase is adopted to solve the problem that a proportional controller cannot overcome residual errors; an automatic quasi-synchronization algorithm of current resistance nonlinear dead zones is provided in the quasi-synchronization phase to guarantee the consistency of the slip frequency. The method provided by the invention is applied in the field of soft start of the synchronous motors.