395 results about "Field weakening" patented technology

A method and apparatus control a power converter (20) of an AC motor drive system (10). The method and apparatus: generate a field current regulating signal to control a field current component flowing from the power converter (20) to the AC motor (30), thereby achieving field current regulation; generate a torque current regulating signal to control a torque current component flowing from the power converter (20) to the AC motor (30), thereby achieving torque current regulation, the torque current regulation having lower priority than the field current regulation; and execute a close-loop field weakening control scheme, which generates a field weakening control command as a function of the difference between a torque current regulation voltage demand and voltage available for torque current regulation. The field current regulating signal is adjusted in accordance with the field weakening control signal to selectively reduce back EMF of the AC motor (30), thereby enabling the step of generating a toque current regulating signal to achieve a toque current component needed to drive the AC motor (30) at a desired speed despite a limitation on DC voltage available to the power converter (20).

Methods and apparatus are provided for an electric vehicle embodying an axial flux traction motor directly coupled to a wheel thereof. The traction motor comprises a stator having coils for producing a magnetic field, an annular rotor magnetically coupled to the stator and mechanically to an output shaft. Permanent magnets of alternating polarity are mounted on the annular rotor. Magnetic shunts bridge a portion of the stator slots above the coils. The magnets are arranged in groups with group-to-group spacing exceeding magnet-to-magnet spacing. Adjacent edges of the magnets diverge. The method comprises, looking up d- and q-axis currents to provide the requested torque and motor speed for the available DC voltage, combining at least one of the d- and q-axis currents with a field weakening correction term, converting the result from synchronous to stationary frame and operating an inverter therewith to provide current to the coils of the motor.

A method of controlling a current command by comparing voltage with a set value needs to vary the set value depending on voltage fluctuation, which involves taking a complicated control. A vector controller for a permanent-magnet synchronous electric motor, according to the present invention, can realize with a simplified configuration a field-weakening operation in a one-pulse mode in a high speed range by providing a current command compensator that corrects a current command by a corrected current command calculated based on a modulation index.

A control system for an electric machine includes a flux weakening module, which includes a voltage magnitude calculator that receives d-axis and q-axis command voltages and that generates a voltage magnitude. An error circuit compares the voltage magnitude to a reference voltage and generates an error signal. A controller receives the error signal and generates a feedback flux correction signal. A limiter limits the feedback flux correction signal to a predetermined flux value and generates a limited feedback flux correction signal. A feedforward stator flux generating circuit generates a feedforward stator flux signal. A summing circuit sums the feedforward stator flux signal and the limited feedback flux correction signal to generate a final stator flux command.

A device to regulate current produced by a permanent magnet machine responsive to a plurality of phase current signals. The motor produces torque for application on a shaft. A processing and drive circuit responsive to a direct current command signal and a quadrature current command signal produces phase current signals for input to the motor. A command circuit responsive to the phase current signals, an angular position of said shaft, and a voltage input command signal to produce a direct current error signal and a quadrature current error signal. A control circuit responsive to the direct and quadrature current error signals produces the direct voltage signal command and the quadrature voltage signal command. The control circuit has a direct and quadrature proportional gain, integrator and clamp circuits. An algorithm produces limited or clamped voltage modulation index signals to obtain maximum efficiency and maximum torque per ampere in the speed range. The algorithm ensures that the current regulator does not run out of voltage by limiting the voltage vector to the achievable voltage vector range that provides maximum torque per ampere and maximum efficiency.

Disclosed herein is a method for controlling an electric power steering system, wherein a motor is controlled by vector control and driven by a current command value calculated on the basis of a parameter such as a steering torque to provide a steering assist power to a vehicle steering system, and further wherein the current command value is limited on the basis of desired output characteristics and a desired angular speed during a field-weakening control and a non-field-weakening control of the vector control.

Systems and methods are disclosed to provide torque linearity in the field-weakening region for an IPM machine. The systems and methods adjust the q-axis and the d-axis components of the stator current commands of the IPM machine using a flux weakening and a torque linearity control loop respectively. Thereby, torque linearity is maintained during the field weakening region of operation of the IPM machine.

Systems and methods are disclosed to improve torque linearity of an electric machine when operating in a field-weakening region. The systems and methods adjust the q-axis and the d-axis components of the stator current commands of the electric machine using a flux weakening control loop and a torque linearity control loop such that torque linearity is maintained when the machine operates in a field weakening region of operation.

The invention relates to an automatic field-weakening method for a built-in permanent magnet synchronous motor, which solves the problem that field-weakening speed is difficult to widen due to the fixed rotor excitation and small reactance of armature reaction of a direct axis in the conventional permanent magnet synchronous motor in the market. In a rotor magnetic structure of the permanent magnet synchronous motor, a magnetic flux short-circuit block is arranged in a magnetic flux isolating layer in a quadrature axis direction with the help of an automatic adjustment action of a spring; when the rotary speed of the rotor is low, the short-circuit block is positioned at a low-speed position so that interelectrode magnet leakage through the isolating layer is small; when the rotary speed of the rotor is increased, the short-circuit block gradually deviates from the low-speed position to move towards the edge of the rotor under the action of rotating centrifugal force, which expands the interelectrode magnet leakage path; and the leakage magnet flux passing through the isolating layer is increased and the main magnet flux is reduced so that the aim of automatic filed-weakening widening speed is fulfilled in the motor body and a larger speed-adjusting range is reached. The method can be applied to the permanent magnet motors which have uncertain pole numbers and tangential or radial magnet structures.

An inverter for a washer performing drive control of an electric motor imparting a rotational driving force required for washing, rinsing and dehydrating operations in a full automatic washer performing the washing, rinsing and dehydrating processes continuously. The inverter comprises a control means for operating the motor with a full field in the low speed rotational region of washing, rinsing and dehydrating operations, with weak field in the high speed rotational region of dehydrating operation, and performing vector control of the output of the motor in the case of full field operation, and voltage / phase control of the motor in the case of field weakening operation.

The invention provides a field weakening control method for a built-in permanent magnet synchronous motor. The method comprises the following steps: motor speed closed-loop control in a field non-weakening region: the output of a speed loop is the current directive value i<*>q of an axis q, the current directive value i<*>d of an axis d is calculated from i<*>q according to an MTPA relation, and i<*>d, i<*>q and the actual feedback values id and iq thereof are subjected to closed-loop control to output the voltage directive values of the axis d and the axis q; difference value amplitude-limiting processing: whether to enter a field weakening region is judged, if yes, an output voltage amplitude value controls a PI (Proportional-Integral) controller to work and controls a PI adjustor to perform difference value amplitude-limiting processing and output Deltaiq, otherwise, the output voltage amplitude value controls the PI controller not to work, and the output is 0; in case of entering the field weakening region, the output i<*>q of the speed loop is only used as the current directive value of the axis d after MTPA calculation, and the sum of the output of the front beat of the speed loop before entering the field weakening region and Deltaiq serves as the current directive value of the axis q in the field weakening region.

A system and method of controlling the power factor for providing either unity, leading or lagging results for the sensorless control of synchronous machines. The system and method provides an estimated angle of the phase current Park vector and uses a floating synchronous reference frame that is shifted from the estimated angle of the phase current Park vector by an angle β to allow the active control and change of the power factor during operation for applications such as producing reluctance torque of a salient pole synchronous machine during Main Engine Start (MES), and field weakening for Environmental Control Systems (ECS) and MES applications.

This invention provides an advanced position and velocity estimation scheme used in a position-sensorless control system for synchronous operation of an electric motor. The system includes an electric motor having a stator and a rotor; an inverter for powering the electric motor; and a controller for controlling the inverter. The controller utilizes a control system comprising a rotor angle and angular velocity estimation block; an estimated angle error detector block; a field-weakening block; and a torque-to-current converter block, all of which operate to generate control commands for operation of the motor.

A control system and method for an electric machine includes a first calculation module that receives a modified torque command and a calculated stator flux command and that generates first and second current commands and first and second voltage commands. A voltage magnitude calculation module generates a voltage magnitude based the first and second voltage commands. A reference voltage calculator module generates a reference voltage based on a DC link voltage, an angular stator velocity and the first and second current commands. A flux weakening module generates the calculated flux command based on the angular stator velocity, the reference voltage and the voltage magnitude.

An electric motor drive device has an inverter adjusting the voltage applied to an AC electric motor so as to drive the AC electric motor, a capacitor which is charged by a current supplied from a DC power supply supplying DC voltage between a neutral point at which a plurality of coils of the AC electric motor are connected and a positive rail or negative rail of an inverter and passing through the inverter, and a control circuit controlling the inverter so that the AC electric motor turns at a designated speed. Further, the control circuit selectively uses field weakening control and voltage boosting control for control of the inverter according to the conditions of the induced voltage generated at the AC electric motor, DC power supply, and voltage of the capacitor.

The invention discloses a control method of an IPM electromotor for driving an electric motor car. According to the working characteristics of the IPM electromotor used on the electric motor car and the characteristics and advantages of various control methods, a segmental control strategy and a method for accurately detecting the start of the electromotor as well as the position and the rotational speed of a rotator during the operation provided are provided. A hall sensor is used for carrying out the method of rough positioning first and scanning next, so that the relatively accurately positioning of the initial position of the rotation in a static state can be realized, the electromotor can be successfully and easily started no matter in the case of idle load, light load or heavy load,and the reliability of the start and operation of the electromotor can be greatly improved. After the IPM electromotor is successfully started, output signals of the hall position sensor undergo rising edge capturing and trailing edge capturing by using software. According to a signal jumping edge, the position of the rotator is corrected in the cases of a low rotational speed and a high rotational speed. When the electromotor operates, a T method is adopted for speed measurement, and an algorithm undergoes certain adjustment in the cases of the low rotational speed and the high rotational speed. When the position and the rotational speed of the rotator during the operation are correctly detected, the segmental control strategy such as peak torque current control and field-weakening control can be adopted so as to ensure that a peak torque is output during the operation of the electromotor.

The permanent magnet brushless motor permits dynamic change of output characteristics by varying the positional relationships of rotor components, with respect to each other and with respect to the stator, to progressively effect field weakening with increasing speeds. The force required to impart the limited range of motion involved is transmitted to the rotor component by way of bearings and / or an actuation motor, and a helical guide path is used to great advantage for constraining such movement. The wide, dynamically adjustable motor output range of the motor effectively provides the equivalent of an efficient, continuously variable transmission. High torque at low speeds, and efficient, constant power output over a wide high speed range, uniquely adapt the motor for use as the prime mover for electric / hybrid vehicles.

The invention belongs to the technical field of controlling of power converters of driving motors, and relates to a current control method for improving the output torque of a permanent magnet synchronous motor overmodulation area. The method includes the steps that a PI controller is adopted to a rotating speed loop; a current controller based on resonance control is used for a dq shaft electric current loop, and parameter setting is carried out on the current controller; the PI controller is adopted in a field-weakening control link, and output of the PI controller serves as a d shaft current set value through an amplitude limiting link; according to set voltage vector dq shaft components output by the current controller, the duty ratio is calculated through an SVPWM overmodulation link, and a PWM signal driving motor is produced. The method suppresses current harmonics caused by flux weakening overmodulation, open-loop gains of the current loop are increased, and current, harmonic and torque fluctuation caused by overmodulation can be effectively suppressed.

An electric motor control device includes a mode in which an inverter is controlled by a current phase of an armature current in a 2-axis orthogonal vector space, a vector being obtained by synthesizing a field and a drive current along two axes defining the vector space; a high-loss control section that, when extra power results from charging a power storage device, varies the field current in accordance with the extra power to increase the armature current while maintaining torque of an AC electric motor; and the high-loss control section varies the field current to one of a field weakening and a field intensifying side of the electric motor, which results in the higher power loss within a range in which the armature current can be output in the vector space and which is determined based on the DC power source voltage and a rotational speed of the electric motor.

A brake system includes an electric brake force generator which brakes a wheel using a driving force of an electric motor and an electric motor controller that performs a field-weakening control of the electric motor. The electric motor controller performs the field-weakening control of the electric motor which then operates the electric brake force generator. Thus, the rotational speed of the electric motor is increased when the field weakening control is performed by the electric motor controller thereby quickly activating the electric braking force generator to enhance response of brake force generation.

A permanent-magnet electrical machine is disclosed in which the rotor has a fixed back iron and movable back iron segments. When the movable back iron segments are in a first position, such as in contact with the fixed back iron, the field strength is high. When the movable back iron segments are in a second position in which the movable back iron segments are displaced away from the fixed back iron, the field strength is low. The ability to weaken the field strength causes the constant-power, speed ratio to be increased and thereby increases the utility of the motor for applications in which a wide speed range is desired. The disclosure applies to both permanent-magnet motors and generators. In an alternative embodiment, the stator ring is provided with a fixed portion and at least one movable stator segment.

A motor control apparatus which controls an output voltage reference for an inverter driving a permanent magnet synchronous motor based on d-axis and q-axis current references, d-axis and q-axis current detected values, and a computed frequency value. When a torque reference specifying torque greater than maximum torque that the motor can output is input, a limit value for a phase angle that is a deviation between a rotation phase reference of control and a rotation phase value of the motor is varied depending on a quantity of the predetermined state.

At a time of a heating high-load operation, a harmonic current is flown in an armature winding to induction-heat rare-earth magnets, thus reducing a residual magnetic flux density. Thereby, the number of rotations of a radial gap type motor is improved. The rare-earth magnets are provided near a cooling medium passage extending substantially in parallel with a flow line of a cooling medium, so that the cooling medium recovers heat of the heated rare-earth magnets. At a time of a cooling high-load operation, a greater number of rotations are obtained with respect to the same torque command value, by a field weakening control by means of a current-phase advance.

A linear actuator is provided with an integral permanent magnet, brushless motor capable of axial, self adjustment of the rotor position within the stator for field weakening. Axial displacement of the rotor within the stator allows for significantly improved speed performance from aligned rotor / stator components during light axial loading. Upon contact with a load, the screw and nut, as an integral part of the motor rotor, self align to fully engage within the stator for generation of high forces with minimal current. This axial shift can further be used as a high precision, low cost measure of the force applied for quality assurance purposes.

A command current setting portion has a target value corrector that calculates d-axis and q-axis current command values idc, iqc that are to be supplied to an open-loop controller, based on d-axis and q-axis current target values id*, iq*. When d-axis and q-axis voltage target value vd*, vq* calculated from the d-axis and q-axis current target values id*, iq* by the motor circuit equations exceed a voltage limit, this target value corrector 26 corrects the d-axis and q-axis current target values id*, iq* by the field weakening control such that d-axis and q-axis voltages vd, vq and d-axis and q-axis currents id, iq satisfy √(vd2+vq2)≦Vlim and √(id2+iq2)≦Ilim respectively. The d-axis and q-axis current command values idc, iqc are obtained by this correction.

Methods and apparatus are provided for rotor and stator temperature compensation for field weakening current. The method comprises generating a phase voltage feed back signal Vph based in part on pre-defined optimal current commands (ID* and IQ*) received by the IPM, generating a phase voltage command (Vphcmd) based in part on a temperature of a magnetic rotor and stator of the IPM, and generating a phase voltage error (Verror) by subtracting the phase voltage feed back signal (Vph) from the phase voltage command (Vphcmd). The method further comprises generating a d-axis command current correction value (ΔId) and a q-axis command current correction value (ΔIq) from the phase voltage error (Verror); and adjusting the pre-defined optimal current commands (ID* and IQ*) by the d-axis and the q-axis command current correction values (ΔId and ΔIq).