An air conditioner and a startup control method and system for an outdoor fan of the air conditioner. While in a process of charging a bootstrap capacitor in an actuator of a motor of the outdoor fan, an initial rotation state of the motor is detected in real time, and, when charging of the bootstrap capacitor is completed, startup of the motor is correspondingly controlled on the basis of the detected initial rotation state. This allows real time initial startup work state to be acquired when charging of the bootstrap capacitor is completed, thus allowing the motor to be started smoothly, increasing the success rate in starting the motor, and solving the problem of low success rate in starting the motor of an outdoor fan.

Provides a method for controlling an AC motor, including: receiving a torque command value; generating a command current based on the torque command, and a command voltage by using the generated command current in a current vector controller (CVC) current control mode; switching to a hexagon voltage manipulating controller (HVMC) voltage control mode when the command voltage enters a voltage limit area, and generating a command voltage in the HVMC voltage control mode; and controlling torque of an AC motor by using the command voltage that is generated in the CVC current control mode or the HVMC voltage control mode.

The first square wave control mode using the square wave pulse pattern is used when the voltage acting on the inverter is equal to or higher than the threshold voltage. On the other hand, when the voltage acting on the inverter is lower than the threshold voltage, a square wave pulse pattern is used when the rotation speed of the motor is equal to or higher than the first predetermined rotation speed that is higher than the first resonance region, and the second square wave control mode using the first switching pattern for suppressing the LC resonance in the first resonance region is used when the rotation speed of the motor is lower than the first predetermined rotation speed.

An apparatus according to the aspect of the embodiments includes a phase determiner configured to determine a rotational phase of a rotor, a speed determiner configured to determine a rotational speed of the rotor, a controller having a first control mode for controlling the motor by supplying constant currents to windings, and a discriminator configured to discriminate whether a rotation of the motor is abnormal based on the rotational speed when the rotational speed corresponding to a command speed is equal to or higher than a predetermined value in a state where the controller is controlling the motor in the first control mode. When a signal output from the discriminator indicates that the rotation of the motor is abnormal, the controller stops the motor. When the signal output from the discriminator indicates that the rotation is not abnormal, the controller continues a drive of the motor.

The invention relates to a method for controlling an inverter which is electrically connected to an electric motor, having the following steps: defining a modulated voltage (S1) for the inverter, said voltage being based on a first switching frequency, for operating the electric motor with a current, wherein the current has an electric frequency; determining the electric frequency (S2); changing the first switching frequency (S4) on which the modulated voltage is based to a second switching frequency if a value pair consisting of electric frequency and first switching frequency, or a value pair consisting of electric frequency and a sideband of the first switching frequency, is within at least one defined disturbance range (S3).

A motor control device includes: a second setting unit configured to set an armature current command value and a current phase angle command value based on a rotation speed and a motor torque command value; and a current vector setting unit configured to set a d-axis current command value and a q-axis current command value based on the armature current command value and the current phase angle command value. The second setting unit is configured to set the armature current command value and the current phase angle command value such that an armature current vector which is set based on the d-axis current command value and the q-axis current command value is included in an area surrounded by an armature current vector locus in maximum torque/current control and a vertical axis in a d-q coordinate system.

The invention relates to a method for controlling an inverter which is electrically connected to an electric motor, having the following steps: defining a modulated voltage (S1) for the inverter, said voltage being based on a first switching frequency, for operating the electric motor with a current, wherein the current has an electric frequency; determining the electric frequency (S2); changing the first switching frequency (S4) on which the modulated voltage is based to a second switching frequency if a value pair consisting of electric frequency and first switching frequency, or a value pair consisting of electric frequency and a sideband of the first switching frequency, is within at least one defined disturbance range (S3).

Provided is a motor control device having a function for determining a rotor position of a synchronous motor, without use of a sensor, the device prevents obtaining an erroneous rotor position, to enable stable control of the synchronous motor based on the rotor position in both the normal-control region and the flux-weakening-control region. The motor control device 1 includes: a first rotor position determining unit 19 that determines a rotor position of the synchronous motor 2 based on a current electrical angle, and a first current phase obtained from a current peak value and a difference between an induced voltage electrical angle and a current electrical angle; a second rotor position determining unit 20 that determines the rotor position of the synchronous motor 2 based on the current electrical angle, and a second current phase obtained from a flux linkage and the current peak value; and a selecting unit 21 that selects the first rotor position determining unit 19 or the second rotor position determining unit 20, based on the current peak value, and the first current phase or the second current phase.

A motor drive device (200) includes: a power conversion circuit (204) that drives an AC motor; and a controller (203) that controls the power conversion circuit. The controller includes: a command current calculation unit (206) that generates a command current according to command torque for the AC motor; a current control unit (208) that performs feedback control for adjusting a current applied to the AC motor to the command current; and a control gain setting unit (207) that calculates a control gain used for the feedback control based on the command torque and sets the calculated control gain in the current control unit. The control gain setting unit performs control such that a time from a decrease of an absolute value of the command torque to switching of the control gain is longer than a time from an increase of the absolute value of the command torque to switching of the control gain. As a result, deterioration of control stability of motor torque during a transient response is avoided.

A sensor is configured to sense current, of one or more output phases of an inverter, associated with back electromotive force (back EMF) of the machine. A converter or electronic data processor is adapted to convert the sensed current into current vectors associated with a stationary reference frame. An estimator or current model is configured to estimate back-EMF vectors from the converted current vectors. A vector tracking observer or the electronic data processor is adapted to mix the back-EMF vectors and applying the mixed back-EMF vectors to a preliminary inertial model. A secondary observer or the data processor is operable to apply the output of the preliminary inertial model to a secondary inertial model in the second speed range to estimate position or motion data for the rotor.