In a motor driving apparatus including an inverter connectable to n motors (n being an integer not less than 2) each including a rotor having a permanent magnet, braking operation is performed on i (i being an integer from 1 to n1) of the n motors, and then braking operation is performed on j (j being an integer from 1 to ni) of the n motors other than the i motors. It is possible to reduce the risks of failure of the inverter and demagnetization of the motors due to overcurrent by reducing current flowing through the inverter and the motors when the braking operation is performed.

A system for reducing a resonant oscillation on a direct current bus is disclosed. The system includes a battery, a first capacitor connected in parallel with the battery, and an inductor connected in series with the first capacitor. The system also includes a first element connected in series with the inductor, a second element connected in parallel with the inductor and the first element, and a second capacitor connected in series with the first element. The system also includes an electric machine connected to the second capacitor. During a re-generation mode for charging the battery, a re-generation current flows from the electric machine to the battery, passing through the first element and the inductor and bypassing the second element. Additionally, during a motor mode, a motor current flows from the battery to the electric machine, passing through the second element and bypassing the first element and the inductor.

A motor control apparatus for controlling a motor, comprises: a driving unit configured to drive the motor; a measurement unit configured to measure a current value flowing to a terminal of each phase of the motor; and an abnormality detection unit configured to short the terminal of each phase of the motor during driving of the motor by the driving unit and detect rotation abnormality of the motor based on the current value measured by the measurement unit during a period of the short.

A motor control apparatus for controlling a motor, comprises: a driving unit configured to drive the motor; a measurement unit configured to measure a current value flowing to a terminal of each phase of the motor; and an abnormality detection unit configured to short the terminal of each phase of the motor during driving of the motor by the driving unit and detect rotation abnormality of the motor based on the current value measured by the measurement unit during a period of the short.

A method for controlling a synchronous motor that has a stator and a rotor, comprising: correcting the frequency, phase, and values of the motor's feeding voltages, as well as the value of its magnetic flux as a function of the angle between stator and rotor magnetic fields vectors of said synchronous motor, wherein said angle derivative an angular speeds mismatch between said vectors.

A method for controlling a synchronous motor that has a stator and a rotor, comprising: correcting the frequency, phase, and values of the motor's feeding voltages, as well as the value of its magnetic flux as a function of the angle between stator and rotor magnetic fields vectors of said synchronous motor, wherein said angle derivative an angular speeds mismatch between said vectors.

An inverter control device that controls an inverter connected to a direct-current power supply and connected to an alternating-current rotating electrical machine to convert electric power between direct current and alternating current of a plurality of phases, the inverter control device including an electronic control unit that is configured to perform, in a state in which one switching element of a plurality of switching elements included in the inverter has a turn-off failure in which the switching element always goes into an off state, torque reduction control for reducing torque of the rotating electrical machine or deceleration control for outputting torque in a reverse direction from a rotation direction of the rotating electrical machine by performing switching control of the plurality of switching elements.

A method of controlling a sensorless motor of an air compressor is provided to overcome the known problems of sensorless control methods and to improve control responsiveness. In various aspects of the present invention, a method of controlling a sensorless motor of an air compressor includes: performing a speed control for stopping a motor by a controller; determining a motor stopped state from an estimated motor speed while the speed control is performed by the controller; determining a rotor position estimated as a fixed position when the motor stopped state is determined by the controller; performing motor position control for moving the rotor position to the fixed position when the motor stopped state is determined; and starting sensorless control for driving the motor by setting the fixed position to an initial position when requesting a motor driving while the rotor position is maintained at the fixed position.

A motor drive system according to an embodiment includes an inverter and a control device. The inverter causes a current to flow through a winding of an induction motor. The control device drives the induction motor by controlling the inverter through vector control. The control device includes a plurality of calculation criteria for a stator magnetic flux estimated value of the induction motor and includes an appropriate magnetic flux command generation unit that selects a calculation criterion for the stator magnetic flux estimated value that further increases a loss of the induction motor from among the plurality of calculation criteria on the basis of at least a rotation speed of the induction motor in the case of braking the induction motor.

A motor drive system according to an embodiment includes an inverter and a control device. The inverter causes a current to flow through a winding of an induction motor. The control device drives the induction motor by controlling the inverter through vector control. The control device includes a plurality of calculation criteria for a stator magnetic flux estimated value of the induction motor and includes an appropriate magnetic flux command generation unit that selects a calculation criterion for the stator magnetic flux estimated value that further increases a loss of the induction motor from among the plurality of calculation criteria on the basis of at least a rotation speed of the induction motor in the case of braking the induction motor.