Abstract: In a conventional cooling device, a heat pipe or a circulation-type liquid cooler provided with a pump is used and therefore, a large space is needed for the cooling device. There is provided a cooling device which includes a plurality of cooling modules having cooling units for cooling heat-generating elements by coolant and radiation units for radiating heat from the coolant heated in the cooling units, the plurality of cooling modules being bubble-pump-type ones in which the coolant is circulated between the radiation units and the cooling units by the coolant being boiled in the cooling units, the radiation units being arranged side by side, and a cooling fan for generating wind blowing the radiation units.

Abstract: A double ended inverter system for an AC electric traction motor of a vehicle is disclosed. The inverter system serves as an interface between two different energy sources having different operating characteristics. The inverter system includes a first energy source having first operating characteristics associated therewith, and a first inverter subsystem coupled to the first energy source and configured to drive the AC electric traction motor. The inverter system also includes a second energy source having second operating characteristics associated therewith, wherein the first operating characteristics and the second operating characteristics are different, and a second inverter subsystem coupled to the second energy source and configured to drive the AC electric traction motor. In addition, the inverter system has a controller coupled to the first inverter subsystem and to the second inverter subsystem.

Abstract: Electric drive units comprising a common active part having a stator and a rotor, which has windings and/or permanent magnets for a drive function and an energy transmission function, enable the rotor winding that is provided for energy transmission to be used to allow position detection at a low additional cost. For this purpose, a power converter in the rotor, which provides the output of electrical energy for the energy transmission function, impresses an alternating voltage into the rotor winding, said voltage being detected in the stator and allowing the rotor position to be determined.

Abstract: A sensorless induction motor control device with a function of correcting a slip frequency wherein a slip frequency estimation unit estimates the slip frequency from at least one kind of current flowing through windings included in the motor, a voltage command signal value calculation unit calculates a D-phase voltage command signal value and a Q-phase voltage command signal value which are used for controlling a voltage applied to the sensorless induction motor using a Q-phase current command signal value calculated based on a difference between a speed estimation value, which is calculated using an estimation value of the slip frequency, and an externally supplied speed command signal value, an ideal voltage command signal value determination unit determines an ideal voltage command signal value using the speed command signal value and the Q-phase current command signal value, an actual voltage command signal value calculation unit calculates an actual voltage command signal value using the D-phase voltage

Abstract: A vehicle drive system comprises inverters connected electrically with a power supply line and a ground line and controlling the current flowing through each stator coil of each of first and second motor generators, and a switch making or breaking the connection between the neutral of the stator coil of first motor generator and a battery. When the first motor generator is not used but the second motor generator is used, a controller brings the switch into connection state in parallel with voltage conversion operation of a booster unit and controls the inverter to perform voltage conversion operation using the stator coil of first motor generator as a reactor.

Abstract: A voltage or power conditioning and control device may be used in line with a source of AC line power and a reactive load such as a single-phase induction motor. The device operates to absorb some of the power reflected by the AC load and generate a synthetic power wave to supplement and correct the applied power in level and phase. The device employs a pair of power capacitors, and a pair of electronic switch devices each with a diode in parallel. Gating or command signals are generated based on the line voltage and timing, e.g., zero crossings. The phase or timing of the command signals is selected for a normal or no-boost mode, a voltage boost mode, or a voltage reduction mode. The capacitors are considered in series with the load, and improve the power factor to the load. A variation of this device may be used in conjunction with a solar array or other local power source.

Abstract: A power converting apparatus including a power converter that converts a DC voltage into an AC voltage and applies the AC voltage to an AC rotating machine and a control unit that controls the power converter based on an operation command from the outside is provided. The power converting apparatus includes: a first calculating unit that calculates and outputs, from a d-axis current detection value and a q-axis current detection value detected by the AC rotating machine and current command values based on the operation command, first voltage command values to the power converter, magnetic fluxes of the AC rotating machine, and an angular frequency; and a second calculating unit that sets, as an initial value, at least one of the magnetic fluxes and the angular frequency input from the first calculating unit and calculates and outputs second voltage command value to the power converter and an angular frequency.

Abstract: Two current threshold values are adopted, which are larger than the upper limit of current of an operating region. When a rotating speed is smaller than a speed threshold value, the current threshold value is adopted as a criterion to judge whether an input current to an inverter is abnormal, and when the rotating speed Rot is larger than that, the other current threshold value is adopted as the criterion.

Abstract: A motor control device performing vector control for a motor that drives a load whose load torque varies periodically. The motor control device has: a motor speed deriving portion estimating or detecting a motor speed; a speed controller producing a specified torque current value such that the motor speed is made to follow a specified motor speed value fed from outside; a resonance filter producing a corrected torque current value by receiving a control value that varies with variations in the load torque and emphasizing a periodic variation component of the control value; a torque current corrector producing a specified superimposed torque current value by superimposing the corrected torque current value on the specified torque current value; and an adjusting portion adjusting, based on the specified superimposed torque current value, a degree of emphasis placed on the variation component by the resonance filter. The vector control is performed according to the specified superimposed torque current value.

Abstract: In an AC motor driving circuit, a current source rectifier is provided on the output side of an AC generator and an AC motor is connected to the output side of the current source rectifier through a voltage source inverter. Along with this, one of terminals of each of a plurality of bidirectional switches is connected to its corresponding output terminal of the voltage source inverter, the other terminals of a plurality of the bidirectional switches are lumped together to be connected to one of terminals of a storage battery, and the other terminal of the storage battery is connected to one of DC input terminals of the voltage source inverter. This eliminates need for a large capacitor at a DC link and a reactor in a chopper which were previously necessary, by which the AC motor driving circuit is downsized.

Abstract: An inverter controller comprising an AC motor as a load. A rectifying circuit converts AC power from an AC power source into DC power. A smoothing capacitor smoothens a DC voltage from the rectifying circuit. An inverter circuit converts DC power supplied via the smoothing capacitor into a desired frequency. A current detection circuit detects a output current of the inverter circuit. A voltage detection circuit detects a terminal voltage (Vpn) of the smoothing capacitor. A voltage command calculation circuit calculates a voltage command to the AC motor. A speed command calculation circuit calculates a speed command to be used when it is determined that the AC power source is in a power failure state or when the terminal voltage (Vpn) reaches a certain value.

Abstract: [Object] To enable stable cargo handling operation and high-efficiency recovery of regenerative electric power by means of simple configuration. [Solution] In a forklift which includes linear actuators that convert rotational motion into linear motion, the linear actuators being provided in a plurality of fork parts of a cargo handling drive device, the forklift includes induction motors that drive each of the plurality of actuators provided in the plurality of fork parts, an inverter that drives the induction motors in the same manner, and a controller that controls the inverter, and the controller computes a slip frequency by using the lowest detection value among detection values from detectors that detect each of rotation speeds of the plurality of induction motors.

Abstract: Systems and methods are provided for controlling a double-ended inverter system having a first inverter and a second inverter. The method comprises determining a required output current and determining a desired second inverter current. The method further comprises determining a second inverter switching function, wherein only a selected leg in the second inverter is modulated at a duty cycle, determining a first inverter switching function based on the second inverter switching function, and modulating the first inverter and the second inverter using the first inverter switching function and the second inverter switching function.

Abstract: A motor driving apparatus having a converter, which receives AC voltage and converts it to DC power, and an inverter, which receives the DC power and converts it to AC power, includes a charge/discharge control circuit and a capacitor connected in parallel to a link section between the converter and the inverter, and energy stored in the capacitor C8 is charged and discharged at arbitrary timing by the charge/discharge control circuit. The invention thus provides a motor driving apparatus that supplies energy to a motor so that the peak of the input current from a power supply to the motor can also be suppressed when particularly large energy is needed during the second half period of motor acceleration.

Abstract: In a control system and a method for operating a permanent-magnet electrical machine, when the electrical machine is switched off after one of a functional computer and a monitoring computer of the control system has identified a fault, in order to reduce the braking torque of the electrical machine, which is switched-off but still rotating an output stage of the control system is subjected to a three-phase short circuit if the rotation speed D1 does not fall below a definable limit value GR1 or if a voltage U_DC of the output stage (2) exceeds a limit value Umax, and when the rotation speed D1 is below the definable limit value GR1 and a voltage U_DC of the output stage does not exceed a limit value Umax, all the circuits breakers (2o1, 2o2, 2o3, 2u1, 2u2, 2u3) of the output stage (2) are opened in order to fully disconnect the electrical machine from the output stage.

Abstract: Power lines are connected to neutral points of motor generators, respectively, and an electric power is transmitted and received between a vehicle and a load outside the vehicle via the power lines. In this transmission, an ECU simultaneously PWM-controls all phases of one of inverters, and controls the other inverter to keep continuously the conducting state.

Abstract: Control systems, methods and power conversion systems are presented for controlling harmonic distortion, in which multi-sampling space vector modulation (SVM) is employed for controlling power converter switching devices, with a reference vector being sampled two or more times during each SVM period to update the SVM dwell times more than once during each SVM cycle.

Abstract: It is attained by being provided with a motor constant calculation unit for calculating electric constants of a motor, and by correcting setting values of electric constants defined on one of the axes of two orthogonal axes, by a functional expression using a state variable defined on the same axis, and by correcting them by a functional expression using a state variable defined on the other axis.

Abstract: An electric motor has a field pole formed by a field current passing through a field winding. A voltage booting converter converts output voltage of a battery and outputs the voltage between a power source line and a grounding line. Field winding is electrically connected onto an electric current channel between battery and power source line and formed so that voltage switched by a switching element is applied to both ends. A controller controls the field current so as to adjust density of magnetic flux between a rotor and a stator by performing switching control on switching element and a switching element connected in parallel to field winding and converts the output voltage of battery into voltage in accordance with a voltage command value.

Abstract: A power conversion device includes a converter that converts AC power to DC power, a converter controller that controls an output voltage of the converter, an inverter that converts the DC power to AC power at a variable frequency, an inverter controller that controls an output frequency of the inverter, and a current detector that detects an AC current on an input side of the converter. It is configured in such a manner that the inverter controller adjusts a slip frequency of the induction motor in response to a fluctuation of the AC current on the input side of the converter detected by the current detector. It thus becomes possible to suppress a beat current in an output current of the inverter at the occurrence of a load fluctuation as well as a power supply voltage fluctuation.

Abstract: A current source rectifier is provided at an output of an alternating current generator, an alternating current motor is connected to an output of the rectifier via a voltage source inverter, furthermore, two arms having switching elements connected in inverse parallel to diodes are connected to the output of the rectifier, and one terminal of a direct current power source capable of a power supply and absorption is connected to a midpoint between the arms, while the other terminal thereof is connected to a neutral point of motor coils or generator coils, thereby eliminating a need for a large volumetric reactor in a direct current chopper, achieving a downsizing of the circuit.

Abstract: A current detector unit has a current detecting portion detecting a current flowing between a three-phase inverter and a direct-current power supply as a detection current; a three-phase current detecting portion for detecting a three-phase current of the inverter based on the detection current; and a judging portion judging, based on the detection current, whether or not a target time point belongs to a period during which the three-phase current can be detected. If the judging portion judges that the target time point belongs to the period, the three-phase current detecting portion detects the three-phase current.

Abstract: If any short-circuit failure occurs in an inverter, then a motor generator is used to execute a safety driving. If the rotational speed of a motor generator calculated from a detection value of a position sensor exceeds a predetermined reference rotational speed during the safety driving, an MGECU turns on all of the switching elements connected in parallel to a switching element in which a short-circuit failure occurs with respect to a power supply line. If the rotational speed is equal to or less than the reference rotational speed, the MGECU turns on only the switching elements connected in series to the switching element in which the short-circuit failure occurs. In this way, any excessive currents can be prevented from occurring in the inverter without restricting the safety driving.

Abstract: A motor driving device that accurately achieves power failure detection according to a power failure tolerance with a relatively simple configuration. A counter input computing unit determines, as a counter input value, a value that is inversely proportional to the power failure tolerance determined from a voltage amplitude value and supplies the counter input value to a counter. The counter accumulates the input value at predetermined intervals and outputs an output value. A comparator determines that power failure occurs if the output of the counter 42 exceeds a threshold value.

Abstract: A double ended inverter system for an AC traction motor of a vehicle includes a fuel cell configured to provide a DC voltage, an impedance source inverter subsystem coupled to the fuel cell, a DC voltage source, and an inverter subsystem coupled to the DC voltage source. The impedance source inverter subsystem, which includes an ultracapacitor, is configured to drive the AC traction motor. The inverter subsystem is configured to drive the AC electric traction motor. The ultracapacitor is implemented in a crossed LC network coupled to the fuel cell.

Abstract: A hybrid vehicle includes: first and second rotary electric machines; a matrix converter connecting the first and second rotary electric machines to each other to provide AC to AC power conversion between both the rotary electric machines; a battery connected to an electrical path branched off between the matrix converter and the second rotary electric motor; an inverter interposed among the battery, the matrix converter and the second rotary electric machine to convert AC power to DC power and vice versa; and a controller. The controller activates the first rotary electric machine with power fed from the battery and restrains the change in torque output of the second rotary electric machine at the activation of the first rotary electric machine.

Abstract: A control controls starting of an AC rotary machine by calculating a resistance drop component, corresponding to a resistance drop of the AC rotary machine, based on a detection current, and adjusts angular frequency of an AC output voltage based on subtracting the resistance drop component from a voltage command, and, simultaneously, adjusting amplitude of the AC output voltage so that amplitude of an AC phase current may change in conformity with a predetermined function.

Abstract: In a motor control method for driving a three-phase motor by an inverter, a dead time compensation operation is performed to compensate for output voltage loss caused by a dead time, in which both a high-side FET and a low-side FET in the inverter are turned off. For example, in a range between 0° and 60° and a range between 120° and 180°, a reference value is provided stepwise to a PWM command value of a U-phase. In a range between 60° and 120°, a doubled reference value is provided stepwise to the PWM command value. A compensated PWM voltage is supplied to the inverter. The stepwise change at zero-cross points, 0° and 180°, is reduced relative to a case, in which a fixed dead time compensation value is provided in a range between 0° and 180°. Torque ripple near the zero-cross point is thus suppressed.

Abstract: To reduce a leakage current when a motor for driving a compressor is energized, with the compressor unoperated. Setting the carrier frequency of an inverter at a value lower than that used during normal operation to cause phase interruption electrification of the motor.

Abstract: A multi-phase AC motor driving device in which occurrence of failure is not erroneously determined is provided. In a multi-phase AC motor driving device including an inverter circuit; current detecting resistances Ru, Rv, and Rw, respectively arranged on lower arm of the respective phase of the inverter circuit, for detecting phase current of the motor; and a control portion and a PWM circuit for controlling ON/OFF operation of switching devices of the inverter circuit, the determination on the occurrence of failure based on the current values detected by the current detecting resistances is not made if relays connected between the inverter circuit and the motor are turned ON and all the switching devices of the lower arms of the respective phases are turned OFF.

Abstract: A power converter interfaces a variable voltage and variable frequency motor to a fixed voltage and fixed frequency network. A first inverter is connected to the motor stator. A dc link is connected between the first inverter and a second inverter. Each inverter includes switches. A filter is connected between the second inverter and the network. A first controller for the first inverter uses a dc link voltage demand signal indicative of a desired dc link voltage to control the first inverter switches to achieve a desired dc link voltage level. A second controller for the second inverter uses a power demand signal indicative of a power to be transferred to the dc link from the network through the second inverter, and a voltage demand signal indicative of a voltage to be achieved at the filter to control the second inverter switches to achieve desired power and voltage levels.

Abstract: Systems and methods are provided for an inverter system for use in a vehicle having a first energy source and a second energy source. The system comprises a motor having a first set of windings and a second set of windings. The first set of windings is electrically isolated from the second set of windings. The system further comprises a first inverter coupled to the first energy source and adapted to drive the motor, wherein the first set of windings are coupled to the first inverter. The system also comprises a second inverter coupled to the second energy source and adapted to drive the motor, wherein the second set of windings are coupled to the second inverter. A controller is coupled to the first inverter and the second inverter.

Abstract: A rotating electrical machine control system includes a rotating electrical machine, a frequency conversion portion, a voltage conversion portion, a torque limitation portion, and an abnormality detection portion. The torque limitation portion limits generation of a positive torque in a region of less than a rotational speed lower limit threshold value where a rotational speed of the rotating electrical machine is less than zero, and sets a region in which the positive torque is generated to a region of the rotational speed lower limit threshold value or greater, and the torque limitation portion limits generation of a negative torque in a region of greater than a rotational speed upper limit threshold value where the rotational speed of the rotating electrical machine is greater than zero, and sets a region in which the negative torque is generated to a region of the rotational speed upper limit threshold value or less.

Abstract: A power converting device for an electric train includes a power converter, an alternating-current motor, a primary control unit, and a control unit. The power converter converts direct-current power into alternating-current power. The alternating-current motor is driven by the alternating-current power output from the power converter. The primary control unit outputs a power-running notch command that determines an acceleration speed for the electric train. The control unit controls an amount of the alternating-current power based on the power-running notch command. The control unit sets the amount of the alternating-current power to zero without a delay after receiving an OFF signal of the power-running notch command during power running.

Abstract: Power conversion systems and methods are presented for damping common mode resonance, in which inverter or rectifier switching control signals are selectively modified according to a damping resistance current value computed using a predetermined virtual damping resistance value in parallel with an output or input capacitor and a measured output or input voltage value to mitigate or reduce common mode resonance in the converter.

Abstract: Systems and apparatus are provided for an inverter system for use in a vehicle. The inverter system comprises a six-phase motor having a first set of three-phase windings and a second set of three-phase windings and a three-phase motor having a third set of three-phase windings, wherein the third set of three-phase windings is coupled to the first set of three-phase windings and the second set of three-phase windings. The system further comprises a first energy source coupled to a first inverter adapted to drive the six-phase motor and the three-phase motor, wherein the first set of three-phase windings is coupled to the first inverter, and a second energy source coupled to a second inverter adapted to drive the six-phase motor and the three-phase motor, wherein the second set of three-phase windings is coupled to the second inverter. A controller is coupled to the first inverter and the second inverter.

Abstract: A voltage command generation unit generates a voltage command value, based on a current deviation relative to a current command value. A dq-axis voltage filter generates a voltage command value subjected to a filtering process for smoothing a change of the voltage command value in a time axis direction. Then, the voltage command value subjected to the filter processing is subjected to a voltage amplitude correcting process and a dq inverse transformation coordinate converting process, so that a phase voltage command for an AC motor is generated. Thus, it is possible to prevent both an amplitude and a phase of the voltage command for the AC motor from being changed rapidly even at a time of control mode switchover.

Abstract: An inverter apparatus is for correcting deviations among current detectors of a three-phase motor. The inverter apparatus includes bidirectional switching elements that have on and off states in the cases in which there are 1 and 0 mean on- and off-states. The states are alternately repeated by controlling the switches, and measurement for correcting the deviations among the current detectors are obtained in the state Currents have the same amplitude flow on a U phase and a V phase. In the state of normal use, the inverter apparatus is operated by correcting detected current values based on the measurement data.

Abstract: An electric power system comprises an AC motor, a first DC voltage unit, an inverter as a power converter, being connected between the AC motor and first DC voltage unit, for exchanging power between these two components; and a controlled DC power supply which is connected between an arbitrary spot of a coil of the AC motor and a positive or negative electrode of the first DC voltage unit and which connects at least one semiconductor switching element and a battery as a second DC voltage unit in series.

Abstract: The apparatus for controlling an inverter is disclosed which detects a rotation angle of a load using a current supplied to the load when the inverter utilizes a voltage/frequency control to control the driving of the load, and accurately drives the load using the detected rotation angle, where the current supplied to the load by the inverter is detected by a current sensor, and a rotation speed of the load is estimated by the detected current to be used for the driving of the load.

Abstract: A controller is capable of executing direct couple control that directly couples a first power device and a second power device without causing a DC/DC converter to convert voltage. During the direct couple control, a drive signal that causes no voltage conversion is intermittently output to at least one of a plurality of switching devices.

Abstract: The invention provides a control apparatus of a power conversion system for driving an induction motor via a VVVF inverter, wherein the AC voltage generated by the inverter is increased so as to expand the high-speed side property of the induction motor, to thereby improve the performance during power running and regenerative braking. In the present system, a DC power supply source having a power storage system with a capacity capable of processing the current flowing into or out of the inverter is inserted in series to the ground side of the input of the inverter, and the output voltage thereof is controlled from zero in a continuous manner to be added to the trolley voltage, which is then applied to the inverter.

Abstract: A miniaturizable, low-cost highly reliable inverter unit. A control circuit section for controlling operating timing of high breakdown voltage semiconductor elements included in an inverter circuit section and first and second drive and abnormality detection circuit sections for outputting drive signals for driving the high breakdown voltage semiconductor elements according to the operating timing and for feeding back an abnormality of the inverter circuit section to the control circuit section are formed on an SOI substrate as one integrated circuit chip. On the integrated circuit chip, circuit formation areas which differ in reference potential are separated from one another by dielectrics. A plurality of level shifters for transmitting signals exchanged between circuit formation areas separated by the dielectrics are formed.

Abstract: A motor in an electric vehicle can be controlled by receiving at least one of a user input or vehicle information, selecting one of a plurality of available flux modes using at least one of the user input or the vehicle information, and calculating a control signal, using the selected flux mode, to control the motor of the electric vehicle.

Abstract: An exemplary power system may include an electric machine with multiple sets of stator windings, each set of windings being coupled through a separate switch matrix to a common voltage bus, and each of which may be spatially arranged in full pitch around the stator such that stator flux harmonics are substantially reduced. The reduced stator flux harmonics may be associated with phase current harmonic content. In an example application, such power systems may operate in a generating mode to transfer mechanical energy to electrical energy on a DC voltage bus. In some illustrative embodiments, the power system may provide both high-power and high-speed (e.g., 1 MW at 8000 rpm or above) motoring and/or generating capability suitable, for example, for on-board (e.g., marine, aviation, traction) power systems.

Abstract: To obtain a converter circuit capable of being made to be small and light-weighted and reducing switching loss, a motor drive control apparatus, an air-conditioner, a refrigerator, and an induction heating cooker provided with the circuit. There are provided: a step-up converter 3a including a rectifier 2, a step-up reactor 4a, a switching element 5a, and a reverse current prevention element 6a; a step-up converter 3b having a step-up reactor 4b, a switching element 5b, and a reverse current prevention element 6b and connected in parallel with the step-up converter 3a; switching control means 7 that controls switching elements 5a and 5b; and a smoothing capacitor that is provided at the output of the step-up converters 3a and 3b. The switching control means 7 switches the current mode of the current flowing through the step-up reactors 4a and 4b into any of a continuous mode, a critical mode, and a discontinuous mode based on a predetermined condition.

Abstract: A double ended inverter system suitable for use with an AC electric traction motor of a vehicle is provided. The double ended inverter system cooperates with a first DC energy source and a second DC energy source, which may have different nominal voltages. The double ended inverter system includes an impedance source inverter subsystem configured to drive the AC electric traction motor using the first energy source, and an inverter subsystem configured to drive the AC electric traction motor using the second energy source. The double ended inverter system also utilizes a controller coupled to the impedance source inverter subsystem and to the inverter subsystem. The controller is configured to control the impedance source inverter subsystem and the inverter subsystem in accordance with a boost operating mode, a traditional inverter operating mode, and a recharge operating mode of the double ended inverter system.

Abstract: The motor driving inverter circuit module includes first-phase, second-phase, and third-phase high voltage drivers generating first-phase, second-phase, and third-phase upper arm and lower arm driving signals in response to input signals for driving the first-phase, second-phase, and third-phase upper and lower arms and a first-phase, second-phase, and third-phase upper arm and lower arm transistors, generating first-phase, second-phase, and third-phase motor driving output signals in response to the first-phase, second-phase, and third-phase upper arm and lower arm driving signals of the first-phase, second-phase, and third-phase high voltage drivers. The first-phase, second-phase, and third-phase high voltage drivers and the first-phase, second-phase, and third-phase upper arm and lower arm transistors are respectively integrated into separate chips.

Abstract: A multi-phase AC motor driving device in which occurrence of failure is not erroneously determined is provided. In a multi-phase AC motor driving device including an inverter circuit; current detecting resistances Ru, Rv, and Rw, respectively arranged on lower arm of the respective phase of the inverter circuit, for detecting phase current of the motor; and a control portion and a PWM circuit for controlling ON/OFF operation of switching devices of the inverter circuit, the determination on the occurrence of failure based on the current values detected by the current detecting resistances is not made if the ON-duty ratios of the switching devices on the upper arms of the inverter circuit are not smaller than a predetermined value.

Abstract: An induction motor control device includes an inverter circuit for driving an induction motor by outputting a command voltage, a current detector for detecting an output current, a magnetic flux estimation observer for generating an estimated magnetic flux, an estimated current, and a phase command for the motor using the command voltage and the output current, a primary angular speed estimator for estimating a primary angular speed using the estimated magnetic flux, a slip compensator for calculating a slip angular frequency using the output current, a first angular speed estimator for estimating a first angular speed using the primary angular speed and the output current, a second angular speed estimator for estimating a second angular speed using the output current, the estimated magnetic flux, and the estimated current, and a resistance estimator for estimating a secondary resistance value of the motor using the first and second angular speeds.