A power tool is provided including: an electric brushless direct current (BLDC) motor having rotor and a stator defining phases; a power unit including a first switch circuit connected electrically between a first power supply and the motor, and a second switch circuit connected electrically between a second power supply and the motor; and a controller configured to control a switching operation of the first switch circuit and the second switch circuit to regulate a supply of power from at least one of the first power supply and/or the second power supply to the motor.

A motor device includes a motor having coils of three phases and a single-phase coil. The motor device includes a drive circuit of a first system capable of supplying a drive current to the coils of the three phases and a drive circuit of a second system capable of supplying a drive current to the single-phase coil. The drive circuit of the second system is different from the drive circuit of the first system. The drive circuit of the first system includes a three-phase inverter circuit connected to one end of each of the coils of the three phases, and the drive circuit of the second system includes a single-phase inverter circuit connected to both ends of the single-phase coil.

A rotating electrical machine including a stator or rotor including a plurality of serially connected switching cells. Each switching cell includes a winding subsection and a current reverser arranged to controllably alter a current direction through the winding subsection, and each current reverser includes a capacitor arranged to form a resonant circuit in cooperation with the winding subsection.

A converter circuit for converting an AC voltage input from a polyphase AC power supply into a DC voltage and outputting the DC voltage includes a positive DC terminal and a negative DC terminal configured to output the DC voltage, diodes each having its anode electrically connected to a corresponding phase of the polyphase AC power supply, and all having their cathodes electrically connected to the positive DC terminal, and a connection portion electrically connecting a neutral point of the polyphase AC power supply and the negative DC terminal to each other.

The present invention provides a driving circuit capable of appropriately switching to a high-torque mode and a high-efficiency mode. The present invention relates to a driving circuit and a driving method for a stepping motor, and an electronic machine using the same. A back electromagnetic force detection circuit detects a counter EMF generated in a coil of a stepping motor. A revolution count detection circuit generates a revolution count detection signal representing the revolution count of the stepping motor. A determining circuit generates a determination signal that is asserted if the revolution count detection signal is stable across multiple consecutive cycles. A current value setting circuit generates a current setting value indicating a target value of a coil current. The current value setting circuit sets the current setting value to a predetermined value in a period in which the determination signal is negated, and adjusts the current setting value according to the counter EMF in a period in which the determination signal is asserted. A constant current chopper circuit generates a pulse modulation signal that modulates by way of having a detection value of a coil current approach close to a target value of the current setting value.

A method for configuring a variable speed drive in charge of power supply of an electric motor. The method comprises the application of a sequence of motor voltages to the electric motor by the variable speed drive and the obtaining, in parallel, of measurements of motor current. The method then determines a feature of the electric motor on the basis of the measurements of motor current and determines a type of electric motor at least as a function of the feature. The variable speed drive is then set up on the basis of the determined type of electric motor.

A method operates a steering device which comprises at least one electric motor that can be operated with an increased torque lying between a nominal torque of the electric motor and a maximum torque of the electric motor over an entire basic setting range. In at least one operating state, a threshold torque of the electric motor is at least temporarily limited to a reduced torque, in particular in comparison to the maximum torque, at least depending on at least one temperature characteristic variable.

A motor controlling device includes a high-side first switching element corresponding to each phase of a three-phase brushless motor, a low-side second switching element corresponding to each phase, a shunt resistor disposed between and connected to the second switching element and a grounding line, and a power controlling section for controlling the first switching element and the second switching element. The device further includes a decision section configured to effect abnormality decision based on a sum of values of currents flowing in the shunt resistors of all the phases acquired by using the power controlling section to switch OFF the first switching element of any one phase whose duty ratio is found equal to or greater than a threshold value for a predetermined period and also to switch ON the second switching element of the same one phase for the predetermined period.

A regenerative drive (30) and method for providing power from such to at least one auxiliary power supply (41, 43) is disclosed. The drive may include a converter (32) and an inverter (34) connected by a DC bus (33), and a controller (54) configured to apply at least one of unipolar modulation and bipolar modulation to the converter (32) and the inverter (34), and to provide about half of the output voltage across the upper portion (130) of the DC bus (33) and about half of the output voltage across the lower portion (136) of the DC bus (33), when the upper and lower portions (130, 136) of the DC bus (33) are unevenly loaded. A first auxiliary power supply (41) may be connected to one of the upper and lower portions (130, 136) of the DC bus (33) and may receive power from the multilevel regenerative drive (30).

A sheet conveyance apparatus includes a stacking unit having a sheet, a feeding unit, a conveyance roller to convey a sheet fed by the feeding unit, a motor to drive the conveyance roller, a phase determiner, first and second controllers, and a discriminator. The feeding unit feeds the sheet. The phase determiner determines a motor rotor rotational phase. The first controller controls a drive current flowing in a motor winding to reduce a deviation between an instructed phase of the motor rotor and the determined rotational phase. The second controller controls to perform a first drive for driving the conveyance roller for a predetermined time before a feeding unit feed operation is started. The discriminator discriminates presence or absence of the sheet at a nip portion of the conveyance roller based on a value of a parameter corresponding to load torque applied to the rotor during the first drive.