According to one embodiment, there is provided a control device including a determination unit, a correction unit and a drive controller. The determination unit determines whether a phase of a rotor of a stepping motor is ahead of or behind a target phase. The correction unit selects a correction value for a control value of a drive current of the stepping motor from among a plurality of correction values based on a determination result. The drive controller corrects the control value of the drive current with the selected correction value to drive the stepping motor.

According to one embodiment, there is provided a control device including a determination unit, a correction unit and a drive controller. The determination unit determines whether a phase of a rotor of a stepping motor is ahead of or behind a target phase. The correction unit selects a correction value for a control value of a drive current of the stepping motor from among a plurality of correction values based on a determination result. The drive controller corrects the control value of the drive current with the selected correction value to drive the stepping motor.

A motor controller includes a temperature sensor configured to detect a temperature of a motor. An intermittent operation circuit allows the motor to intermittently operate at a rotation speed up to a phase before the motor reaches a rated rotation speed when it is detected that the motor temperature is at a low temperature range. The intermittent operation circuit includes a position fixing circuit configured to allow a constant electric current to flow through stator coils and to fix the motor in a stopped state. The intermittent operation circuit further includes a forced commutation circuit that allows the motor to rotate at a rotation speed up to the start-up rotation. The position fixing circuit allows the constant electric current to have a greater value as the temperature detected by the temperature sensor is lower, and allows the position fixing circuit and the forced commutation circuit to operate alternately.

A motor controller includes a temperature sensor configured to detect a temperature of a motor. An intermittent operation circuit allows the motor to intermittently operate at a rotation speed up to a phase before the motor reaches a rated rotation speed when it is detected that the motor temperature is at a low temperature range. The intermittent operation circuit includes a position fixing circuit configured to allow a constant electric current to flow through stator coils and to fix the motor in a stopped state. The intermittent operation circuit further includes a forced commutation circuit that allows the motor to rotate at a rotation speed up to the start-up rotation. The position fixing circuit allows the constant electric current to have a greater value as the temperature detected by the temperature sensor is lower, and allows the position fixing circuit and the forced commutation circuit to operate alternately.

An electrical drive includes an electrical machine, a first converter stage connected to terminals of stator phase-windings of the electrical machine, and a second converter stage connected to intermediate points of the stator phase-windings. A control device determines first component currents and second component currents so that torque is generated in accordance with electrical machine control and magnetic levitation force is directed to a rotor of the electrical machine in accordance with levitation control when portions of the phase-windings between the terminals and the intermediate points carry both the first and second component currents and the other portions of the phase-windings carry the first component currents. The reference currents for the first converter stage are determined based on the first and second component currents, and the reference currents for the second converter stage are determined based on the second component currents.

According to one embodiment, a controller of a stepping motor includes a table generating unit and a current controlling unit. The table generating unit generates a data table of a threshold by using values of induced voltage at frequencies of switching signal that changes a set value of a drive current, the threshold being proportional to a frequency of the switching signal within an operation region in which the frequency of the switching signal is lower than a predetermined frequency, the values of the induced voltage including a first induced voltage generated at a first frequency of the switching signal and a second induced voltage generated at a second frequency of the switching signal. The current controlling unit controls a value of the drive current in accordance with a comparison result between the threshold and an induced voltage that is detected at a frequency lower than the predetermined frequency.

According to one embodiment, a controller of a stepping motor includes a table generating unit and a current controlling unit. The table generating unit generates a data table of a threshold by using values of induced voltage at frequencies of switching signal that changes a set value of a drive current, the threshold being proportional to a frequency of the switching signal within an operation region in which the frequency of the switching signal is lower than a predetermined frequency, the values of the induced voltage including a first induced voltage generated at a first frequency of the switching signal and a second induced voltage generated at a second frequency of the switching signal. The current controlling unit controls a value of the drive current in accordance with a comparison result between the threshold and an induced voltage that is detected at a frequency lower than the predetermined frequency.

A motor drive device that drives motors with one inverter includes a step-out control unit that detects step-out in which the operating frequency of at least one of the motors does not match the inverter output frequency, or the operating frequency of at least one of the motors does not match the operating frequency of another one of the motors, and stops the motors by switching an energization state of the inverter when at least one of the motors is out of step.

A motor drive control device has a controller and a driver. The controller generates a control signal for controlling driving of a two-phase stepping motor so as to alternately repeat one-phase excitation in which a coil of one phase in coils of two phases of the two-phase stepping motor is excited and two-phase excitation in which the coils of two phases in the coils of the two phases are excited. The driver drives the coils of the two phases, based on the control signal. The controller determines, based on a back electromotive force generated in the coil that was not excited during the one-phase excitation, a period of performing the one-phase excitation, and determines, based on the period of the one-phase excitation performed before the two-phase excitation, a period of performing the two-phase excitation.

A motor drive control device has a controller and a driver. The controller generates a control signal for controlling driving of a two-phase stepping motor so as to alternately repeat one-phase excitation in which a coil of one phase in coils of two phases of the two-phase stepping motor is excited and two-phase excitation in which the coils of two phases in the coils of the two phases are excited. The driver drives the coils of the two phases, based on the control signal. The controller determines, based on a back electromotive force generated in the coil that was not excited during the one-phase excitation, a period of performing the one-phase excitation, and determines, based on the period of the one-phase excitation performed before the two-phase excitation, a period of performing the two-phase excitation.