Abstract: A robot system having a plurality of component units. The robot system includes a first storage device, and a second storage device. The robot system further includes a plurality of control device, with a first component control device provided with the first component and a second component control device provided with the second component wherein the first component control device controls the first component device and the second component control device controls the second component.

Abstract: System and method for controlling a synchronous machine are provided. The method allows for calculating a stator voltage index. The method further allows for relating the magnitude of the stator voltage index against a threshold voltage value. An offset signal is generated based on the results of the relating step. A respective state of operation of the machine is determined. The offset signal is processed based on the respective state of the machine.

Abstract: A motor drive control system suitable for control of a drive of a motor, such as a brushless motor or a linear motor, having a plurality of excitation phases, through the use of rectangular waves. A drive means is provided for producing an excitation signal to be supplied to each of the excitation phases of the motor and a control means for determining a direction of the excitation signal for each of the excitation phases and for conducting ON/OFF switching. The control means controls the rate of change of the excitation signal to be switched at the switching operation.

Abstract: In a method of operating and controlling hysteresis motors energized by a three-phase power supply and individually monitored by an operating monitoring system, whereby the effective power output of the individual motors is determined and the three-phase voltage is changed if the effective power output deviates from a predetermined range, the hysteresis motors are first energized at an intermediate range voltage until they reach nominal speed and are then running at synchronous speed, the supply voltage is then increased to an upper range, where the remanent magnet pole strength is impressed on the armature and then reduced to a lower range for continuous operation of the motors, the power output of the individual motors is monitored and, if it drops below a threshold indicating a switch to asynchronous operation, the operating voltage is again increased to the intermediate range for renewed synchronization.

Abstract: A motor current detection amplifier detects a motor current's areas in two phase periods with reference to a motor voltage. A controlling microcomputer computed the ratio of the motor current areas of the two phase periods and provides the same as phase difference information which is in turn used to control a motor drive voltage to apply a sine wave of a predetermined period to the motor's coil to allow 180°-driving including a sine wave conduction resistant to noise and achieving a reduced cost hike.

Abstract: A motor control system 16 for use within an electric vehicle 10 having an induction motor 12. Control system 16 utilizes a torque control module 18, a vector control module 20 and a space vector PWM module 22 to efficiently and accurately control the torque provided by motor 12.

Abstract: An electric power steering device constructed to detect a steering force by a driver and a vehicle speed respectively by a torque sensor and a vehicle speed sensor, set a steering force assisting current for a motor by a steering force assisting current setter using the detected steering force and the detected vehicle speed, set an upper limit value of a motor current by a motor current upper limit value setter based on a power function of a deviation between the set steering force assisting current and a predetermined motor current reference value, and perform overheat protection by setting an upper limit of a motor current applied by a motor driving circuit based on an integrated value of the motor current squared, whereby a problem of an insufficient steering assisting force when stationary steering is repeated many times while parking in a garage in a narrow parking area is solved.

Abstract: In a robot device, its functions and performance can be improved with ease. According to the present invention, control device detachably mounted on a prescribed component unit for driving and controlling each of the component units in a prescribed state is provided and thereby, the control device can be easily exchanged for a new one. Thus the robot device in which its functions and performance can be improved can be realized. Further, according to the present invention, a robot device comprises storing device detachably mounted on the prescribed component unit for storing desired behavior type information and thereby, the storing device can be readily exchanged for storing device storing behavior type information different from the behavior type information stored in the former storing device. Thus, the robot device in which its functions and performance can be improved with ease can be realized.

Abstract: A control apparatus for estimating the flux, the current, and the speed of an AC motor using the current and the voltage, and controlling the vector of an AC motor using the estimated speed, a flux command, and a torque current command. The speed is estimated by adding a product of the deviation between the actual value and the estimated value of a magnetization current, the level of a torque current correspondence value, the sign correspondence value of a primary frequency command value, and a gain to an outer product of an estimated current deviation and an estimated flux. Thus, a stable speed estimating operation can be performed to successfully operate the motor in a low speed area in which a voltage frequency applied to the motor is extremely low.

Abstract: An induction motor control system (10) for electric vehicles having a DC power supply (14), an inverter (16), an induction motor (12), a motor controller (26) and a vehicle-level controller (32). The method and system of the present invention optimizes the torque output for the induction motor and utilizes minimum power. The method and system of the present invention calculates the flux current such that the slip frequency is maintained at a nominal level, thereby producing peak torque.

Abstract: A polyphase induction motor is operated by an inverter drive system comprising a logic level controller. A number, preferably twelve or more, of independently driven phases causes harmonic fields, up to a number equal to the number of phases, to oscillate in synchrony with the fundamental oscillating field. A pulse-width modulation (“PWM”) carrier is used by the logic level controller to synthesize a desired drive alternating current, in which the pulsing distortion produced by the pulse width modulation produces a synchronous oscillating field in the driven polyphase induction motor.

Abstract: If a speed instruction value is less than a predetermined value, the output current of a power-conversion unit is controlled to be larger than a current value in an ordinary no-load operation, or a frequency instruction value is calculated based on a speed instruction value in place of an estimated speed.

Abstract: A method for reducing the starting time and reducing the peak phase currents for an internal combustion engine that is started using an induction machine starter/alternator. The starting time is reduced by pre-fluxing the induction machine and the peak phase currents are reduced by reducing the flux current command after a predetermined period of time has elapsed and concurrent to the application of the torque current command. The method of the present invention also provides a strategy for anticipating the start command for an internal combustion engine and determines a start strategy based on the start command and the operating state of the internal combustion engine.

Abstract: A method and a control device for braking a variable speed vector controlled induction machine are driven by a pulse width modulation (PWM) inverter, in which the q-current component and the d-current component of the stator current are controlled independently from one another in accordance with a first reference signal (iq*) and a second reference signal (id*), respectively. For braking, high frequency components are superimposed on the second reference signal (id*), and the root-mean-square (rms) value (id rms) and the average value (id av) of the resultant second reference signal are controlled independently from one another such that the field requirements are met by the average value and high machine losses are produced by the rms value.

Abstract: A speed sensorless controller for an induction motor with rotor resistance estimation, using stator currents and voltages. The rotor resistance and speed estimation are obtained as a solution of a linear algebraic system with pseudo current and voltage signals and their observable derivatives as inputs. The proposed scheme provides accurate, real-time estimation of the speed and rotor time constants in all motor operational modes. It can also be used for real-time motor tuning if a speed signal is available.

Abstract: A method of regulating a rotary machine powered by a voltage inverter receiving, as input a control voltage delivered by a regulator servo-controlling the electromagnetic torque on a reference value, the regulator receiving as inputs the reference value and sat least one sampled signal representative of the torque of the machine, and proceeding at each sampling instant, to predict the torque value at a following sampling instant and to modify the control voltage accordingly.

Abstract: A floating frame controller determines a current Park vector, selects a reference frame for the current Park vector, and adjusts the reference frame until a quadrature component of a current Park vector in the adjusted reference frame is equal to a predetermined value, whereby a synchronous reference is established. The synchronous frame is used to control a power converter. The floating frame controller can drive a synchronous machine without the use of rotor position sensors.

Abstract: A synchronous motor control system includes a synchronous motor 1, an inverter 3 and a controller 4 wherein a current differential detecting unit 13 detects a variation of a motor current when the three phases of the motor 1 is short circuited by the inverter 3, namely at the moment when a carrier wave in a PWM signal generator 9 assumes maximum or minimum value, in a calculating unit 14 a phase &ggr; from &agr; axis of a stationary coordinate system to a three phase short circuited current differential vector is calculated, a phase &dgr; is estimated from d axis to the three phase short circuited current differential vector by making use of d axis current id and q axis current iq on d-q axes coordinate system in the controller 4, thereafter the magnetic pole position &thgr; with respect to &agr; axis is calculated from the phases &ggr; and &dgr;, based on thus calculated magnetic pole position &thgr;, d-q axes control units 11, 7 and 8 are constituted to control the synchronous motor, thereby a highly reliab

Abstract: A three-phase-to-two-phase converter detects two-phase currents of three-phase stator currents, converts the stator currents into a &ggr;-&dgr; coordinate system to derive a &ggr;-axis current and a &dgr;-axis current. The &ggr;-axis current, the &dgr;-axis current, and voltage command values outputted respectively from a &ggr;-axis current controller and a &dgr;-axis current controller are entered to a stator current and induced electromotive force estimator, which determines estimated values of the stator currents and estimated values of an induced electromotive force in the &ggr;-&dgr; coordinate system.

Abstract: A control circuit for selectively energizing at least one electrical device coupled to the control circuit via a pair of conductive wires with an operating voltage. The control circuit comprises a control circuit for selectively supplying and withholding operating electrical power to at least one electrical device. A first current detector is connected to a control voltage and senses a current flow resulting from closure of a circuit connected to a control voltage in at least one wire of the pair of conductive wires. A second current detector is connected to the operating voltage and senses a current flow resulting from closure of a circuit connected to the operating voltage in at least one wire of the pair of conductive wires. A first switching device responds to the first current detector to disconnect the control voltage from at least one of the wires and to connect the operating voltage to the conductive pair.

Abstract: In a brushless motor driving circuit of the invention, in the starting operation, an applying voltage is low and also the induced voltage is low, so that output values from sample and hold circuits 6 and 7 are substantially equal to each other. Thus, an output from a comparing circuit 10 is substantially equal to an output of a V/f converting circuit 11. As a result, the starting method which is identical with a conventional method is used. By contrast, when the number of rotation of a brushless motor 1 is increased, and the induced voltage is started to be observed, the condition is spontaneously shifted to that in which the driving voltage is automatically controlled at each time to an appropriate value for the number of rotation and the load of the motor. Accordingly, the switching operation from the starting control to the normal control is not required.

Abstract: A method and apparatus for maintaining both a DC bus voltage and a motor current within limit values wherein, when a voltage limit condition occurs, a voltage error (i.e. DC bus voltage limit minus DC bus voltage) is used to increase an inverter output frequency until the voltage limit condition subsides, and, wherein during a current limit condition a current error signal (i.e. motor current limit minus motor current) is used to reduce inverter output frequency until the current limit condition subsides, a slew rate used to control the output frequency when neither a current nor a voltage limit condition exists, the slew rate decreased as a function of the voltage limit period durations and increases a function of the current limit period durations.

Abstract: The method for controlling a voltage/frequency converter controlled single-phase or polyphase electric motor evaluates the phase shifting between the EMF and BEMF by way of the deviation between the zero crossing of the phase current and the voltage produced by the intrinsic induction and readjusts the frequency of the converter accordingly. The measurement of the intrinsic induction is effected in the zero crossing of the current courses of the associated phase, wherein during the measurement the phase is separated from the supply network.

Abstract: A motor controller controls a motor operated by an AC line voltage. The controller includes an SCR connectable between an AC line and a motor terminal for controlling application of AC line voltage to the motor. A voltage sensor is operatively associated with the SCR to sense voltage across the SCR. A control circuit is connected to the sensor and the SCR for varying relative duration of on time and off time during each cycle of line voltage to control motor voltage at a reference level. The control circuit determines if a motor stall condition occurs responsive to the sensed SCR voltage and, in response to determining that a motor stall condition occurs, reducing motor voltage by decreasing duration of on time to protect the solid state switch means SCR.

Abstract: A method for removing spurious signals in a process of motor current signature analysis of an electric motor (24 or 33) includes creating an electronic model of the motor, acquiring simultaneous measurements of voltage and current at the motor, applying the voltage measurement to the motor model and determining an equivalent current produced in the motor model by the applied voltage, subtracting the equivalent current from the current measurement to produce a corrected motor current, and processing the corrected motor current through motor current signature analysis. For an ac motor (33), the method includes extracting signals corresponding to the fundamental excitation frequency from the voltage measurement to produce an interfering voltage, processing the interfering voltage through the motor model to produce a corresponding spurious current signal, and subtracting the spurious current signal from the measured current to produce the corrected motor current signal for analysis.

Abstract: An induction motor control device includes a power conversion circuit, a current sensor, a current component calculation circuit for calculating first and second current components, a magnetic flux command calculation circuit for calculating a magnetic flux command value such that the amplitude ratio between a squared value of the first current component and a squared value of the second current component takes a preset value, a voltage component calculation circuit for calculating a primary voltage component command value, and a primary voltage component command calculation circuit. The current component calculation circuit calculates first and second current components in phase and 90° out of phase with the primary voltage component command value, respectively.

Abstract: An estimated rotation angular velocity □r0 and an estimated secondary resistance Hr0 are processed using a first feedback gain H1 under a condition that a first state deviation E1 is in phase with a quadrature component of an estimated secondary magnetic flux □r01. An estimated primary resistance Rs0 is processed using a second state deviation H2 under a condition that a second state deviation E2 is in phase with an estimated primary current 02. These values are used to control the speed of an induction motor without an angular velocity detector.

Abstract: An apparatus for controlling an actuator in response to a target speed voltage signal, the actuator having a moveable member and having a coil that influences movement of the member. A first summing node is provided having a control output voltage, for summing or subtracting voltages applied thereto, as the case may be and receiving the target speed voltage signal at a first, summing input thereto. A proportional compensation unit is provided, receiving the control output voltage and providing as an output a proportionally compensated output signal. An integral compensation unit is provided, receiving the control output voltage and providing as an output an integrally compensated output signal. An inverse compensation unit is provided, receiving the target speed voltage signal as an input and providing an inversely compensated output signal having a voltage corresponding to the voltage of the target speed voltage signal multiplied by the inverse of a predetermined amplification factor.

Abstract: A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is squared. The squared outputs associated with each winding are combined, with the square root being taken of such combination, to produce a DC output proportional only to the rate of rotation of the motor's shaft.

Abstract: A DC motor driven power steering system for a motor vehicle includes a motor current detection circuit for detecting a motor current flowing through the DC motor, a power supply voltage detection circuit for detecting a power supply voltage applied to the bridge commutation circuit, a motor voltage estimating unit for estimating a voltage applied across the DC motor on the basis of the power supply voltage applied to the bridge commutation circuit and the pulse-width modulated control signals used for controlling the bridge commutation circuit, and a motor rotation detecting means for detecting the rotation state of the DC motor on the basis of the motor current and the estimated motor voltage applied to the DC motor. High reliability can be ensured for detection of the rotation state of the DC motor.

Abstract: A drive for controlling the speed of an AC induction motor from an inverter. The inverter applies a voltage to the stator winding of the motor in accordance with the magnitude of a first input signal. The inverter causes the voltage to be applied at a frequency determined by the magnitude of a second input signal to the inverter. The drive includes motor speed sensor and a motor speed reference signal source coupled to a speed regulating amplifier. A slip detector determines the slip of the motor from the speed of the rotor and the energization frequency of the stator winding. A slip regulating amplifier receives the output signal from the speed regulating amplifier and the slip signal and provides an output to a summing amplifier. The summing amplifier also receives a motor speed signal and provides an output. The output comprises the second input signal to the inverter. The output may be supplied through an absolute value circuit as the first input signal to the inverter.

Abstract: In an inverter controlling method for an induction motor, the slip of the motor is detected and an optimum slip which is dependent on the motor constant and the frequency supplied to the motor providing the highest efficiency is calculated, and a voltage manipulated variable is determined from a comparison of the optimum slip and the slip of the motor, and then the voltage manipulated variable is used to form an output voltage instruction or a magnetic flux instruction so that running of the induction motor is controlled with the slip with which the highest efficiency is provided with respect to load variation and frequency variation.

Abstract: The three-phase power controller is provided which has interrupt-controlled phase-gating control with a simple, cost-effective design. The power controller uses of a single microcontroller with only one or two interrupt inputs. This is made possible by forming voltage zero signals, whose flanks are used for interrupt control. Interrupt routines in the executive program of the microcontroller control the times when trigger signals are emitted, exclusively on the basis of the voltage zeroes as information about the three-phase mains system.

Abstract: A BEMF detector and method detect the BEMF of a three-phase motor using a fully differential detection system. The motor has a first coil coupled between a first coil tap and a center tap, a second coil coupled between a second coil tap and the center tap, and a third coil coupled between a third coil tap and the center tap. The BEMF detector includes a differential amplifier having first and second inputs and first and second outputs, with the first input being coupled to one of the coil taps and the second input being coupled to the center tap. The BEMF detector also includes a comparator having first and second inputs coupled respectively to the first and second outputs of the differential amplifier and an output at which a BEMF signal is produced that is related to the BEMF of the motor. The differential amplifier may be part of an anti-alias filter structured to fix to a known stable value a common mode at the outputs of the differential amplifier.

Abstract: In a process for controlling a rotating machine having n phases powered by a voltage inverter defining m.sup.n states of the stator phase voltage vector the electromagnetic torque .GAMMA. and the stator flux .vertline..phi..sub.s .vertline. of the machine are servocontrolled. A calculator calculates a succession of n states of the phase voltage vector to move the torque .GAMMA. and the flux .vertline..phi..sub.s .vertline. towards the set points .GAMMA..sub.ref, .vertline..phi..sub.s .vertline..sub.ref. On each sampling, the calculator calculates the remaining application time of the current state and the updated application times of the future states of the phase vector. Asynchronously with the sampling times and the calculation times, the calculator sends SPmLL switch control signals to switch from the current state to the next state.

Abstract: In a switched reluctance motor and control system for such a motor, a rotor comprises four salient poles each having a width of about 50-degrees, and a stator has six salient poles each having a width of about 30-degrees. One Excitation winding is mounted around each stator salient pole and these are connected in series. An excitation drive circuit supplies a dc excitation current to each excitation winding to excite the motor in accordance with an excitation command signal. A torque-current drive circuit renders a current, whose magnitude in accordance with a torque command, to flow into torque windings mounted one round on each of the six stator salient poles successively according to the angle of rotation of the rotor.

Abstract: An apparatus for controlling an actuator having a moveable member and having a coil that influences movement of the member, by provision of a drive current to the coil in response to a target speed voltage signal. The invention includes an up/down counter, counting at a predetermined count rate and providing a count output. A control unit is provided for controlling the direction of count of the up/down counter depending on whether the voltage across the coil, sensed periodically a first predetermined interval after the drive current to the coil is interrupted, is greater than, or less than, a reference voltage having a predetermined relationship to the target speed voltage. A digital-to-analog converter is provided, responsive to the count output to provide a compensated voltage signal having a voltage corresponding to the count output.

Abstract: A method for the field-oriented control of an induction motor (2) by means of a frequency converter (1) is disclosed, in which method a transformation angle (.delta.) is determined by estimation and is corrected in dependence on a rotational speed (.omega..sub.mR) of a rotor flux vector (i.sub.mR) or of the induction motor (2) and/or in dependence on a delay time (T.sub.del). In this connection it is desirable to improve the control behavior. To that end, the transformation angle (.delta.) is corrected a second time to compensate for a phase shift in the frequency converter (1).

Abstract: A motor is reconnected to a motor drive by exciting the motor to induce a back EMF, determining a speed of rotation of the motor based on the induced back EMF induced, and reconnecting the motor drive to the motor based on the speed determined. In order to induce the back EMF, current which flows through the motor is controlled using first and second regulators. The outputs of the first and second current regulators are separated from each other in phase by approximately 90.degree.. A positive feedback loop is established by using the output of one of the first and second regulators to generate an input for the other one of the first and second regulators. The positive feedback loop advantageously causes the back EMF to continually increase as the motor continues to be excited, or at least not decay so rapidly that the speed of the motor cannot be accurately determined.

Abstract: A method and apparatus for starting a motor drive into a rotating motor, the method including determining an initial search frequency and search current wherein the current is less than a rated drive current, providing a d-axis flux generating current to the motor at the search frequency and at a magnitude equal to the search current, monitoring a q-axis flux error, decreasing the search frequency until the d-axis flux error is less than a threshold value, thereafter increasing the search current to the rated drive current and, after a flux-up period, providing both q-axis torque producing current and d-axis flux producing current to the motor.

Abstract: In a motor with permanent magnets and a motor system, the value .alpha. produced by dividing, by the induced voltage constant ke, the product of the inductance Lm of the motor itself or the inductance Ls of the motor system in the d-q coordinate system is selected to meet a predetermined condition. The range of rotational speeds in which the motor can be operated while maintaining a predetermined output under field weakening control can be widened. If a condition is established to determine a ratio by which the rated rotational speed under normal operating conditions is multiplied into a rotational speed under field weakening control, then conditions for a motor or a motor system that can be used can be determined.

Abstract: An induction motor drive uses direct vector control for zero speed start up. According to the invention, a speed sensorless induction motor is controlled at all speeds, including zero or substantially zero speed, using direct vector control. In order to utilize direct vector control at all speeds, it is necessary to derive accurate stator flux vectors at all speeds. This is accomplished in the present invention by calculating two sets of stator flux vectors in diverse manners. A first set of flux vectors is derived from measured stator terminal voltage quantities, and a second set of flux vectors is derived from measured stator current quantities. The first set of flux vectors is valid at non-zero speed and the second set of flux vectors is valid at substantially zero speed. The direct vector control utilizes one of the two sets of flux vectors in accordance with predetermined criteria indicative of zero and non-zero speed conditions.

Abstract: A voltage-type inverter device includes a 1/2 V(DC) detecting circuit (31) for detecting a voltage between one end of a DC power supply (3) and an output from an inverter circuit (4); a voltage command value setting means (29) for commanding an output voltage from the inverter circuit; a first arithmetic means (32) for receiving the voltage command from the voltage command value setting means (29) and a detection voltage from the 1/2 V (DC) detection circuit (31) to produce an error voltage; a second arithmetic means (33) for receiving the error voltage from the first arithmetic means (32) and a voltage command value from the voltage command value setting means (29) to produce a voltage corrected command value; and a PWM signal generator (12) for receiving the voltage corrected command value from the second arithmetic means (33) and a frequency command value commanding a frequency command value from the inverter circuit to create a PWM signal for driving the inverter circuit.

Abstract: A control apparatus for an asynchronous machine, in particular as a drive for electric vehicles, is equipped with an incremental transducer for the rotation speed of the asynchronous machine and a torque setpoint transducer, the signals of which can be delivered to a setpoint-value entry device in order to generate setpoint values (three-phase reference sine-wave system) for a closed-loop-controlled inverter or inverter power section to operate the asynchronous machine. The setpoint-value entry device contains means for defining at least the rotor frequency (slip frequency) and the amplitude as a function of the desired torque setpoint value. The setpoint-value entry device contains a summing device for adding or subtracting the rotor frequency to or from the mechanical rotation frequency, corresponding to the rotation speed, of the asynchronous machine as a function of the instantaneous rotation direction, the desired rotation direction, and the direction of the desired torque.

Abstract: In a vector control apparatus and method for an induction motor, a magnetic flux observer of a full order is provided for receiving a primary voltage vector (v.sub.1) and a primary current vector (i.sub.1) and for generating a vector related to an estimated secondary magnetic flux component to be supplied to a current command calculating section and related to an estimate rotation phase of a rotary coordinate system to be supplied to a current controlling section based on the primary voltage vector and the primary current vector, the magnetic flux observer of the full order having a plurality of coefficients expressed in circuit constants of a T-I type equivalent circuit of the induction motor.

Abstract: A method and apparatus used with a field oriented motor controller for providing corrected transient inductance estimates during normal motor operation. The invention monitors q-axis feedback and command voltages and, based on an error therebetween, modifies a transient inductance estimate to compensate for the error and force the feedback voltage to equal the command voltage thereby facilitating field oriented control. The invention can be used either during a commissioning procedure to provide an inductance correction table for use during normal motor operation or can be used during normal motor operation to tune the inductance estimate.

Abstract: A power conversion system, including a converter for converting an AC power from a power source to a DC power, a DC capacitor for smoothing the DC power output from the converter, an inverter for converting the DC power smoothed by the DC capacitor to an AC power of an arbitrary frequency to drive and control an induction motor, a unit for detecting or computing a magnetic flux axis of the induction motor, a unit for computing a current orthogonal to the detected or computed magnetic flux axis, and a phase control unit for controlling a phase angle of an output voltage of the inverter so that a value of the current orthogonal to the detected or computed magnetic flux axis is maintained at a constant level.

Abstract: A method and apparatus for detecting the presence of a ground leakage path in an electric motor system including an alternating current (ac) electric motor coupled for receiving electric power from a switching inverter of the type having, for each phase of the motor, a pair of serially connected electronic switching devices connected between relatively positive and negative direct current (dc) voltage buses with the switching devices being alternately gated into and out of conduction for providing switched electric power to the motor. The inverter includes a current detector for detecting current in the relatively negative voltage bus. The method comprises initially applying a gating pulse each time the motor is energized to the switching device of each phase connected to the negative voltage bus and identifying a ground leakage path when such gating pulse produces current at the current detector.

Abstract: A method for generating electrical frequencies of a alternating current motor is disclosed wherein a torque current command signal, a d-axis voltage command signal and a d-axis voltage feedback signal are combined to generate the stator electrical frequency in the synchronous reference frame. The method also provides an estimate of the rotor electrical frequency as well as of the motor speed. The frequency generator is preferably incorporated in a variable frequency motor controller for driving a motor at desired speeds independent of changing load conditions. The generator permits the controller to maintain field oriented control without the need for speed sensing and feedback.

Abstract: A power control system in combination with a three-phase AC motor coupled to a water pump enables the operation of the motor at speeds up to 10,800 RPM so as to provide improved pumping capacity with a smaller motor and smaller pump. The control system supplies AC power to the motor with a frequency of the power being increased at a first high rate up to a frequency at which pump pressure is about equal to a value at which water is being pumped from the outlet pipe of the pump. Thereafter, AC power frequency is increased to the second, slower rate up to a maximum operating frequency of the motor. During the time that frequency of the AC power is being increased, motor current is continuously monitored and compared to a maximum allowable current. If monitored current exceeds allowable current, the frequency of operation is decreased until monitored current is less than the allowable current. Thereafter, frequency is again increased so long as monitored current is less than allowable current.