Abstract: The invention relates to a method of adjusting motor parameters in a variable speed drive intended for controlling a synchronous electric motor with permanent magnets M. The method comprises a step of determining the deviations ?ID and ?IQ between references and measurements of the flux current and motor torque current, a step of calculating a correction value ?RS of the stator resistance, a correction value ?L of the inductance and a correction value ?KE of the flux constant of the motor, on the basis of the integral terms of the deviations ?ID and ?IQ, a step of adjusting the values of the parameters of the motor model on the basis of ?RS, ?L and ?KE, a step of formulating the control voltages UD and UQ to be applied to the motor M by using the said adjusted values of the motor parameters.

Abstract: A motor control unit includes a power converter unit that energize a motor based on a commutating signal, the motor having a rotor provided with a permanent magnet and a stator having a coil wound thereto; a start-up controller that outputs a commutating signal to the power converter unit during a start-up operation, the commutating signal having a predetermined conductive pattern corresponding to a command rotational speed; a voltage calculator that calculates a voltage of the motor during the start-up operation by applying a parameter for the motor, the command rotational speed, and a current flown in the coil of the motor to a voltage-current equation of the motor; and a determiner that, during the start-up operation, compares a voltage calculated by the voltage calculator and an actual voltage of the motor and that determines occurrence of rotational abnormalities when the actual voltage is lower than the calculated voltage.

Abstract: A variable-flux motor drive system including a permanent-magnet motor including a permanent magnet, an inverter to drive the permanent-magnet motor, and a magnetize device to pass a magnetizing current for controlling flux of the permanent magnet. The permanent magnet is a variable magnet whose flux density is variable depending on a magnetizing current from the inverter. The magnetize device passes a magnetizing current that is over a magnetization saturation zone of magnetic material of the variable magnet. This system improves a flux repeatability of the variable magnet and a torque accuracy.

Abstract: The invention includes a motor controller and method for controlling a permanent magnet motor. In accordance with one aspect of the present technique, a permanent magnet motor is controlled by, among other things, receiving a torque command, determining a normalized torque command by normalizing the torque command to a characteristic current of the motor, determining a normalized maximum available voltage, determining an inductance ratio of the motor, and determining a direct-axis current based upon the normalized torque command, the normalized maximum available voltage, and the inductance ratio of the motor.

Abstract: A motor controller (2) for an axial-gap motor (1), which has a rotor (3), two stators (4, 5) disposed on both sides of the rotor (3) in the axial direction, and armature windings (6, 7) wrapped around the stators (4, 5), includes a field current controller (43, 44) which adjusts the field current in the current supplied to the armature windings (6, 7) of at least one of the stators (4, 5) so as to restrain a thrust force acting on the rotor (3) in the axial direction of the rotor (3). This restrains the thrust force acting on the rotor (3) of the axial-gap motor (1).

Abstract: The drive circuit (10) includes a processing and control circuit (14) comprising a protection circuit (16), designed to generate at its output a logical inhibiting signal (C) starting from every zero crossing of the motor supply volts (V), the inhibiting signal (C) having a predetermined duration (t0) which is less than a quarter of the period of the supply voltage (V); and an enabling circuit (17), connected to a sensor of the position of the rotor (6) and designed to enable a first and a second controlled conduction device (12, 13) associated with the stator winding (4) to conduct current alternately, in synchronization with the signal (H) supplied by the position sensor (6). The enabling circuit (17) is connected to the protection circuit (16) in such a way that the conduction of current through the controlled conduction device (12, 13) enabled at any time is inhibited for the duration (t0) of the inhibiting (C).

Abstract: In a motor driving control device, a high-frequency alternating voltage or rotation voltage (having a frequency of ?h) is applied to a motor so that magnetic saturation occurs in the motor, thereby extracting, from a ?-axis current, a high-frequency second-harmonic component (a frequency component of 2×?h) that is obtained by attenuating at least a direct-current component of the ?-axis current. The polarity checker detects the polarity of the magnetic pole of the rotor based on the difference, caused by magnetic saturation, between the positive and negative amplitudes of the high-frequency second-harmonic component.

Abstract: A control device of a rotating electric machine to which an inverter is integrally assembled is downsized, and manufacturing costs are reduced. An inverter for controlling outputs from the rotating electric machine is integrated with a rotating electric machine, and in which a control device forming an inverter is constructed of a switching element and a heat sink, a drain electrode terminal of the switching element is directly joined to the heat sink, and a source electrode terminal and gate electrode terminal of the switching element are joined to a metal pattern formed at a connection member.

Abstract: A control apparatus for an AC rotary machine, including first voltage command calculation means for calculating first voltage commands from current commands, an angular frequency, and constant set values of the AC rotary machine, second voltage command calculation means for calculating second voltage commands on the basis of difference currents between the current commands and current detection values, so that the difference currents may converge into zero, third voltage command calculation means for calculating third voltage commands by adding the first voltage commands and the second voltage commands, voltage application means for applying voltages to the AC rotary machine on the basis of the third voltage commands, and constant measurement means for calculating the constant set values on the basis of the second voltage commands.

Abstract: A smart actuator that includes a driving device and an electric actuator such as a DC motor includes a driving current detecting circuit, a driving circuit connected to the electric actuator, a control circuit that controls the driving circuit according to current data provided by the current detecting circuit to supply the electric actuator with a set amount of driving current when the electric actuator has a designed operating condition and a correction circuit that corrects the current data of the driving current if the operating condition is shifted from the designed operating condition to supply the set amount of driving current to the electric actuator.

Abstract: A method for the control of a wound rotor synchronous motor comprises measuring a plurality of electromagnetic entities indicative of the operation of the motor, generating voltage on a stator of the motor to obtain a stator current, further generating a further voltage on the rotor to obtain a rotor current, before the generating and the further generating, the entities being processed to calculate references for the stator current and for the rotor current, the references corresponding to the generation by the motor of the maximum torque obtainable per ampere of stator current supplied.

Abstract: An object is to provide a driving device capable of smoothly shifting from a starting state to a sensor-less vector control, in a case where the device drives a motor by the sensor-less vector control, and the device includes a voltage detecting circuit which detects an induced electromotive voltage of the motor. A control circuit starts the motor by rectangular wave control. A magnetic pole position of a rotor is detected based on an induced electromotive voltage of one remaining phase of the motor detected by the voltage detecting circuit. The control circuit controls a main inverter circuit based on the detected magnetic pole position, and accelerates the motor by the rectangular wave control. In a case where a predetermined shift revolution speed is reached, the control circuit shifts to vector control by the sensor-less in which the magnetic pole position detected during the rectangular wave control is used as an initial value.

Abstract: A power converter for a switched reluctance motor (SRM) or a permanent magnet brushless direct current (do) motor (PMBDCM) may include a front-end boost partial circuit for connecting with a first phase winding of the motor to form a front-end boost circuit and a back-end boost partial circuit for connecting with a second phase winding of the motor to form a back-end boost circuit. The front-end boost partial circuit generates a first step-up voltage in cooperation with the inductance provided by the first phase winding. The back-end boost partial circuit generates a second step-up voltage in cooperation with the inductance provided by the second phase winding.

Abstract: A field-winding type of synchronous machine comprises a stator with an armature winding wound phase by phase, a rotor having a rotor core with a field winding wound, and a circuit enabling an armature current to pass the armature winding, the armature current corresponding to a synchronous current producing a rotation field rotating at an electrical-angle rotation speed agreeing to a rotation speed of the rotor. The synchronous machine further comprises a current suppressor and a current supplier. The current suppressor is connected to the field winging and suppresses, into a unidirectional current, an induced alternating current induced through the field winding in response to the armature current passing the armature winding. The current supplier supplies, phase by phase, to the armature winding a rotor exciting current whose waveform is different from the synchronous current only during a predetermined period of time shorter than one cycle of the synchronous current.

Abstract: A system and method is provided for improved monitoring and controlling of mechanically commutated DC motors. The system and method include DC motors, pulse-count driver circuitry for driving the motors, motor position sensing circuitry, and motor control circuitry. The system and method provide for improved motor current waveform sensing that is able to effectively reject false brake pulses, avoid erroneous processing due to fluctuating battery voltage levels, and reduce the sensitivity to variations in motor current signals due to dynamic motor load, manufacturing variation, system aging, temperature, brush bounce, EMI, and other factors. The system and method also include an improved ability to multiplex additional external motor drivers to the motor control circuitry, select between sequential and simultaneous drive modes using an SPI bit, and monitor the system controller for an error condition and drive the connected motors in response to the error condition.

Abstract: A method and system for controlling a current regulator motor control for parking a motor rotor in a predetermined position, wherein a first current command and a first angle command are supplied to a current regulator for a first parking time, to move the rotor to an intermediate position; and a second current command and a second angle command are supplied to the current regulator for a second parking time, to move the rotor to a predetermined position. The current regulator may have a normal voltage output range, and a circuit may be provided for limiting a voltage output of the current regulator to a reduced voltage output range for at least a portion of the parking time. Advantageously the motor is a permanent-magnet synchronous motor with sinusoidal back-EMF.

Abstract: An electric motor system having a rotor with a plurality of permanent magnets, and a stator having a winding through which current is flowing for driving the rotor. A control unit controls the current flowing through the winding. The control unit employs a first filter and a second filter, each filter is connected to the winding and has outputs coupled to a comparator. The comparator compares the signal output of the first filter to the signal output of the second filter. The control unit controls the current flowing through the winding depending on the result of the comparison of the two filtered signals.

Abstract: A direct current motor controlling method includes a mean for transforming a duty signal to computed value by a microprocessor unit. The microprocessor unit computes the computed value and then produces a target value by executing a dichotomy method, a rotation method and a transformed function, capable of reducing executing time and executing load of the microprocessor unit and saving memory space. The microprocessor unit sends a frequency signal to a driving circuit unit according to the target value. The driving circuit unit receives the frequency signal and then provides a driving voltage to a power switch. The power switch provides a voltage to a direct current motor or not according to the driving voltage for controlling output performance of the direct current motor.

Abstract: A single-phase induction motor and a method for reducing noise in the same, which can eliminate unbalance between magnetomotive forces of main and auxiliary windings in a stator of the motor, thereby implementing a low noise, low vibration motor, and can also achieve balance between the magnetomotive forces of the stator windings in the entire running range of the motor, and can further achieve balance between the magnetomotive forces of the stator windings on the basis of temperature increase of the motor as it runs. The amplitude of a main-winding current flowing through the main winding in the stator is controlled to be equal to the amplitude of an auxiliary-winding current flowing through the auxiliary winding in the stator, and the phase difference between the main-winding and auxiliary-winding currents is controlled to be maintained at a predetermined value.

Abstract: A method of starting a permanent magnet machine. A machine stator voltage in a stationary reference frame is sensed. An initial speed of a rotor of the machine is estimated based on the sensed voltage, and state variables of control algorithms are initialized based on the estimated initial speed. This method can provide smooth startup and/or restart at any speed.

Abstract: On a training device, in particular for developing human muscles, having a torque-generating unit which comprises an electric motor and a reduction gearing, and whose output interacts with at least one training element offered to the exercising person, an electric motor is designed as a three phase AC motor. Associated with the latter is a frequency converter for adjusting the frequency and amperage of the three phase current supplied to the electric motor. A control unit is provided upstream of the frequency converter. An angle-of-rotation sensor is associated with the motor whose measured signal is supplied to both the frequency converter and the control unit. The frequency converter is fed by the control unit with a setpoint value of the torque to be generated by the motor which setpoint value receives the measured signal from the angle-of-rotation sensor. The frequency converter adjusts the frequency and the amperage of the motor current using the principle of field-oriented control.

Abstract: It is an object of the invention to provide a method which can detect a magnetic pole position easily and surely by using high-frequency currents such as harmonics of an inverter output and carrier frequency components. The invention provides a method of detecting a magnetic pole position of a motor and an apparatus for detecting a magnetic pole position in which, although high-frequency currents of carrier frequency components or the like are used, a special current detecting circuit is not required, and synchronization between the current detection timing and the position calculation can be easily attained, and also to provide an apparatus for controlling a motor using the same.

Abstract: An influence resulting from double saliency of an electric motor, i.e., an influence of a deviation of the axis of an alternating current due to a rotor magnetic pole position ? on the estimation of a magnetic pole position, is eliminated, and, in particular, the magnetic pole position of a double saliency electric motor can be estimated with high precision.

Abstract: A vector control device of a winding field type synchronous machine with which even when voltage changes caused by resistance voltage falls and inductance fluctuations due to armature current occur the armature voltage is controlled exactly to a desired command value and a high power supply utilization percentage is maintained at all times. An absolute value of armature voltage is calculated from an armature voltage command value or an armature voltage detected value, and the armature voltage is controlled by a flux command being regulated so that this absolute value of armature voltage approaches a desired armature voltage command value. Also, the armature voltage command value is regulated so that the loss of the synchronous machine becomes minimal with reference to the armature current and the field current.

Abstract: In sensorless vector control performed through use of a rotation speed of a synchronous motor 6 and the position of a rotor, a positive current is caused to flow to a ? axis on the assumption that a “d” axis serving as a true magnetic axis is out of phase with the ? axis by only an angle of load ?e, whereby torque which is proportional to i? sin ?e and directed toward the ? axis arises in the magnetic axis. Accordingly, a deviation between a d-q axis serving as a true magnetic axis and a ?-? axis serving as a control axis is eliminated. Even if load is exerted on the motor, the ? axis serving as a control axis is constantly aligned with the “d” axis serving as the magnetic axis of the synchronous motor, thereby enabling excellent vector control.

Abstract: A system and method for reducing the cost of producing a brushless DC motor (58) is presented. The brushless DC motor (58) provides higher power density and efficiency with an increased tool run time. The brushless DC motor (58) includes a rotor assembly (72) that has an unmagnetized permanent magnet (74) affixed to a shaft. The permanent magnet (74) remains unmagnetized until the motor is partially assembled. A plurality of coils (94) for producing a magnetic field are wound about the rotor assembly (72). The coils (94) include end turns that enclose the rotor assembly (72) such that the rotor assembly (72) is not removable. Since the windings (94) are wound with the rotor assembly (72) already enclosed, the windings (94) do not require large end coils to allow subsequent insertion of the rotor (72). Minimizing the end coils reduces the length of wire required per turn, thereby reducing the resistance of the winding (94).

Abstract: A stepping motor control apparatus in accordance with the present invention comprises: a current detection unit that detects phase currents flowing into a stepping motor; an equivalent model-of-motor arithmetic unit that includes a coefficient multiplication block which performs multiplication using a coefficient ka?=Ts/? as a multiplier, a coefficient multiplication block which performs multiplication using a coefficient kb?=?/(Ts+?) as a multiplier, and a coefficient multiplication block which performs multiplication using a coefficient kg?=I0/E0 as a multiplier, and that calculates an estimated angle of excitation; a current control unit that controls an exciting current on the basis of the estimated angle of excitation, an angle command, and the phase currents detected by the current detection unit; and a variable voltage inverter that applies phase voltages to phase windings included in the stepping motor according to outputs of the current control unit.

Abstract: A stepping motor driver according to the present invention includes a torque component current calculating means for calculating a torque component current from phase currents and a rotor rotation angle, an absolute value converting means for obtaining an absolute value of the torque component current, a high speed-response judging means adapted for outputting a first control signal when a speed deviation between a command speed and a rotor speed is not more than a reference level, and outputting a second control signal when the speed deviation exceeds the reference level, and a current command outputting means adapted for outputting a current command according to the absolute value of the torque component current when the first control signal is outputted, and outputting a maximum current command value as the current command when the second control signal is outputted.

Abstract: A synchronous machine control device includes a flux command generator, a magnetic flux estimator, a divider, a flux controller and ?- and ?-axis armature current controllers. The flux command generator produces a flux command from the synchronous machine turning speed. The magnetic flux estimator calculates the magnitude and phase of armature flux linkage from armature currents and field current taking into consideration magnetic fluxes produced by permanent magnets. The divider produces an armature current command by dividing a torque command by the armature flux linkage. The flux controller determines a field current command based on an error of the magnitude of the armature flux linkage from the flux command.

Abstract: In a conventional rotation state detecting apparatus of a synchronous machine, since short-circuiting must be carried out twice or more when a rotation speed is detected, there have been problems in that it takes a time to detect a rotation state, and it takes a time to start up. A rotation state detecting apparatus for a synchronous machine according to the present invention has been made to solve the above problem, and includes a calculation unit for outputting a voltage vector command and a trigger signal and for outputting a rotation state of a synchronous machine having at least three windings in an idle state, a circuit unit for applying voltages to the respective phases of the synchronous machine on the basis of the voltage vector command, and a detection unit for detecting a current of the synchronous machine on the basis of the trigger signal and outputting a value of the detected current to the calculation unit.

Abstract: A DC motor drive circuit includes a position detector for producing an output signal that corresponds to a rotational position of the rotor, a current controller for controlling current supply to the winding in accordance with the output signal of the position detector, and a phase advancing portion for the current between the position detecting portion and the current controller, so that the timing for supplying current to the winding is advanced and efficiency of converting the current supplied to the winding into a motor torque is improved.

Abstract: Two inverters (INV1, INV2) supply phase currents to three-phase coils (Y1, Y2). Although two phase currents must conventionally be measured and four current sensors are thus required, according to the present invention, the number of phase currents to be measured is reduced as a result of use of an observer for phase current estimation.

Abstract: A brushless direct current motor drive circuit having a serially connected motor coil energizing circuit, a serially connected feedback circuit, a pre-drive circuit, a position sensor, and a duty ratio controller. This circuit can decrease the heat generation from the switching elements on the power source side, perform absorption of the current flowing back in the direction of the switching elements on the power source side when the duty ratio is set to less than 100% without using an electrolytic capacitor group that causes a shortening of the motor lifetime, and solve various problems caused by the use of an electrolytic capacitor group.

Abstract: A sensorless switched reluctance machine includes a stator with a plurality of circumferentially-spaced stator segment assemblies that include salient stator poles and inter-polar stator slots. Each of the stator segment assemblies includes a stack of stator plates forming a stator segment core, an end cap assembly, and winding wire wound around the stator segment core and the end cap assembly. The rotor defines a plurality of rotor poles. The rotor tends to rotate relative to the stator to a rotational position that maximizes the inductance of an energized winding. A sensorless drive circuit derives rotor position and energizes the winding wire around the stator segment assemblies based on the derived rotor position. Each stator plate includes a first radially outer rim section and a tooth section that extends radially inwardly from a first center portion of the first radially outer rim section.

Abstract: A process to start a brushless direct current motor with a multiphase stator winding is disclosed, in which, during rotor standstill, a plurality of current impulses is intruded on the stator winding, the current rise time until a current threshold is reached is measured in the stator winding with every current impulse and the rotor position is derived from the measured current rise times. A more precise determination of rotor position is achieved with lower control-related effort for a regulated sensorless start-up in that a plurality of test current impulses is successively intruded on the stator winding in such a way that the test current impulses generate stator flow vectors offset by the same angular increments over 360° electrically in the stator. The current rise time for each stator flow vector is measured in the total current of the stator winding and the phase position of the stator flow vector with the smallest current rise time is determined as the rotor position.

Abstract: A method and a device for regulating a polyphase machine, in particular a synchronous machine, in which a direct-axis voltage and a quadrature-axis voltage are determined as manipulated variables of the regulating system, and also including a pulse-width-modulation inverter which generates the phase voltages of the individual phases and is triggered to operate either in PWM mode or in block mode as a function of the operating mode of the electric machine. To simplify the hardware component of the regulating device, PWM control signals and block control signals are generated via software and sent to a PWM/block signal device as a function of the operating mode, the device being capable of generating either PWM signals or block signals as a triggering signal for the pulse-width-modulation inverter as a function of the control signal supplied.

Abstract: The present invention relates to a method for the sensorless electric measurement of the position of a rotor of a permanently excited synchronous machine that is fed by a converter, by means of measuring signals which are sent to an evaluation device that calculates the electric position of the rotor from the angular dependence of the current space vector at an impressed stator flux pattern, wherein the distribution of absolute values of the differential current space vector varies in approximation in sinusoidal manner with twice the value of the electric rotor position angle sought.

Abstract: A switched reluctance drive is controlled without using a physical rotor position detector. The control method estimates the standing flux-linkage associated with the phase and uses this estimate to improve its estimate of rotor position. The method works robustly regardless of whether the current is continuous or discontinuous.

Abstract: The stepping motor driver comprises an inverter for feeding stepped currents to windings of a stepping motor, a position detector for obtaining a detected angle of a rotor of the stepping motor and a current controller for controlling the inverter. In a d-q rotational coordinate system in which the d-axis is in the direction of the magnetic flux of the rotor and the q-axis is in the direction perpendicular to the d-axis, an excitation angle for a winding is determined from a d-axis component and a q-axis component of a command current to the winding, a lead angle control signal is computed from the excitation angle, and a phase of an applied voltage to the stepping motor is controlled using the lead angle control signal.

Abstract: A method controls an electric vehicle which is so constituted as to drive a synchronous motor by way of a switch and an inverter circuit. A battery acts as a source of driving a controlling power. The synchronous motor has a permanent magnet acting as an outer rotor. The method includes the following operations of: 1) detecting that the electric vehicle has an acceleration signal of zero; 2) detecting that an actual speed of the electric vehicle is less than a predetermined percent of a rated speed; 3) supplying a current to a winding of a fixed phase of the synchronous motor, by way of the inverter circuit; and 4) generating a braking force.

Abstract: Disclosed is a single-phase motor including a stator, a rotor adapted to rotate when electric power is applied to the stator, a ring-shaped magnet coupled to the rotor to rotate along with the rotor; a parking magnet for stopping the rotor within an effective torque generating region by a magnetic force effected between the ring-shaped magnet and the parking magnet upon braking the rotor, and a sensor unit for sensing a variation in the intensity of a magnetic field generated around the ring-shaped magnet during the rotation of the rotor, thereby sensing the position and speed of the rotor. In accordance with this configuration, the additional device used for an initial driving operation and subsequent operations of the motor can be relatively simple and inexpensive. As a result, there is an advantage in that the motor has an enhanced utility.

Abstract: A control device which controls the current supplied to a motor (1) comprises a phase sensor (2) which detects a rotor phase of the motor (1) at a predetermined angular resolution, and outputs a phase signal corresponding to plural phase determining ranges, a motor drive device (4, 5), and a controller (3). The controller (3) selects one method from plural different methods which determine a current control rotor phase from the phase signal, computes the current control rotor phase from the phase signal using the selected method, computes a command value of the current supplied to the motor (1) using the computed current control rotor phase, and outputs this to the motor drive device (4, 5).

Abstract: Method and system for controlling a permanent magnet machine are provided. The method provides a sensor assembly for sensing rotor sector position relative to a plurality of angular sectors. The method allows starting the machine in a brushless direct current mode of operation using a calculated initial rotor position based on angular sector position information from the sensor assembly. Upon reaching a predefined mode-crossover criterion, the method allows switching to a sinusoidal mode of operation using rotor angle position based on extrapolating angular sector position information from the sensor assembly.

Abstract: A variable motor (1) having reduced audible noise. This advantage is achieved by reducing or eliminating ripple torque by making the individual phase torques follow a certain profile, so that when the torques are summed, they are substantially constant. Therefore, the motor (1) back EMF is used as a reference waveform to control the winding currents to achieve reduced ripple torque. The back EMF reference is amplified and provided to the motor windings, and may be derived in a number of ways including use of sense windings, electronic derivation, and approximation by sensing the voltage applied to the windings.

Abstract: A rotation detection circuit of a dc brushless motor using a fixed bias voltage includes a transistor, and a signal adjuster. The signal adjuster is connected in series between the transistor and driver circuit of the dc brushless motor, for adjusting a signal output by the driver circuit to the according to a fixed bias voltage. The signal adjuster can be selectively supplied with a fixed bias voltage or connected in series with a zener diode. The signal adjuster can be adjusted according to the characteristics of the motor driver circuit, thereby enhancing the design of the rotation detection circuit.

Abstract: An electronically commutatable motor, whose excitation windings are controllable via semiconductor output stages by an electronic control unit with the aid of PWM control signals, a setpoint value being specifiable to the control unit, and the control unit emitting corresponding PWM control signals to the semiconductor output stages; a motor characteristic curve, from which an assigned nominal operating speed is derivable for the setpoint value being stored in the control unit, and the derived nominal operating speed being able to be compared to the actual speed of the motor. It a predefinable or predefined speed difference between the nominal operating speed and the actual speed is exceeded, the control unit and/or the semiconductor output stages can be switched off. The derivation of the nominal operating speed for the predefined setpoint value is facilitated by a three-dimensional characteristics field determined by four coordinate points.

Abstract: A rotor angle detecting apparatus for a DC brushless motor is capable of detecting the angle of the rotor of the DC brushless motor with accuracy without the need for a position detecting sensor. A motor controller has a high-frequency voltage imposer, an angle detector, a U-phase current sensor, and a W-phase current sensor for detecting the rotor angle of the DC brushless motor. The angle detector detects the rotor angle &thgr; using a current value IU_s detected by the U-phase current sensor, a current value IW_s detected by the W-phase current sensor, and high-frequency components depending on high-frequency voltages vu, vv, vw, when the high-frequency voltages vu, vv, vw are imposed on command values VU_c, VV_c, VW_c for three-phase voltages by the high-frequency voltage imposer.

Abstract: A control apparatus controls a voltage applied to an AC motor from a power converter with a PWM signal, and has two different magnetic pole position-estimating units which estimate a rotor magnetic pole position of the AC motor, and has a switching unit which selects any one of these two kinds of magnetic pole position-estimating units.

Abstract: A synchronous motor drive system in accordance with the present invention detects a DC current of an inverter which drives a synchronous motor, and based on the magnitude of the current, estimates torque current components that flow through the motor, and then based on the estimated value, determines the voltage which is applied to the motor, and finally estimates and computes the magnetic pole axis located inside the motor using the estimated value of the torque current.

Abstract: Axial error calculation unit is provided for estimating an axial error &Dgr;&thgr; between a d-q axis and a dc-qc axis by using Ld, Lq, Ke, Id*, Iq*, Idc and Iqc in a range of all rotational speeds except zero of a rotational speed command of a synchronous motor, Ld denoting an inductance on a magnetic pole axis d of the synchronous motor, Lq an inductance on a q axis orthogonal to the magnetic pole axis d, Ke a generated power constant of the motor, Id* a current command of the d axis, Iq* a current command on a q axis, Idc a detected current value on an assumed dc axis on control, and Iqc a detected current value on an assumed qc axis orthogonal to the assumed dc axis. Irrespective of presence of saliency, position sensorless control can be achieved in a wide range a low to high speed zone.