A control circuit of a motor control device estimates an initial magnetic pole position of a rotor using an inductive sensing scheme. When estimating the initial magnetic pole position, a drive circuit applies a voltage to a stator winding at each of L electrical angles (L5) while changing the L electrical angles. An absolute value of an electrical angle difference of the voltage applied to the stator winding between an i-th time (2iL) and an i1st time is 180360/L degrees or more and 180+360/L degrees or less. An absolute value of an electrical angle difference of the voltage applied to the stator winding between a 1st time for initial position estimation and a last time before starting initial position estimation is 180360/L degrees or more and 180+360/L degrees or less.

Provided is a brushless DC motor (2) including: a stator (5) around which windings are around; a magnet rotor (6) configured to rotate by a power supply to the stator; an inverter circuit (11) connected to the stator; a position detector (7) configured to detect a positional relationship between the magnet rotor and the windings; a speed instruction unit (13) configured to output, as a speed instruction signal, a voltage corresponding to a rotation speed of the magnet rotor; a duty determination unit (12) configured to determine a duty of a voltage applied to the stator, based on the speed instruction signal; a drive controller (14) configured to distribute and output a duty signal based on the positional relationship and the duty; and temperature-sensitive resistance elements (15) configured to, by increasing the resistance in response to a temperature rise, reduce the voltage given as the speed instruction signal.

Embodiments of the present disclosure provide a method for controlling a fan, a system, and an air conditioner. The method includes: turning off a first bridge arm group in an inverter of the fan; applying a preset driving signal to a second bridge arm group in the inverter; detecting an electrical signal of a stator of the fan after the preset driving signal is applied; determining an initial state of the fan according to the electrical signal of the stator of the fan, wherein the initial state of the fan includes a downwind forward state, a static start state, or an unwind reverse state; and providing the fan with a control signal matching the initial state of the fan according to the initial state of the fan.

An example motor includes: a rotor with a plurality of alternate polarity permanent magnets; and a stator forming a like number of poles. The stator forms one or more biasing features concentrating magnetic flux at at least one location. In some examples, the stator has an interior surface unbroken by locating features, and the stator has one or more openings that form the one or more biasing features.

The present disclosure generally relates to an electronic circuit and method of operating thereof to back up write cache data on DDR memory in data storage devices during an emergency power off (EPO). The method involves using a power management integrated circuit (PMIC), a combo driver and one MOSFET for regulator output. The method involves detecting a voltage value that is below a predetermined threshold value, retracting a write head away from a hard disk drive (HDD), backing up data, and then resetting the HDD after the backup is complete. The backing up and retraction may occur in parallel or in sequence. The method utilizes the spindle back-electromotive force (BEMF) power to have sufficient power to make the backup. If the power from the spindle BEMF is too low, then the retraction is suspended and a high impedance is present to lighten the load until the BEMF recovers before the power on reset. As such, the back-up data is not reset and volatized by a lack of power.

A converter having a negative DC terminal and a positive DC terminal; at least three AC terminals, each AC terminal being arranged for an associated AC current to flow through the terminal, a converter bridge with at least three bridge legs, each bridge leg being associated with one of the at least three AC terminals and being able to connect the associated AC terminal to the negative DC terminal or the positive DC terminal; and a current measurement circuit having a current measurement element, the current measurement circuit being configured to guide either none or one or more of the AC currents flowing through one of the at least three AC terminals through the current measurement element.

A motor control apparatus includes a current estimation unit configured to output a detected current value corresponding to each of the three-phase AC currents based on the measured current value and rotor rotation angle information of the motor. The current estimation unit defines a phase whose duty ratio of a driving pulse supplied to an inverter circuit, which generates the three-phase AC currents, becomes more than or equal to an operation switching threshold as an estimation target phase, calculates, for the estimation target phase, an estimated current value based on a coefficient value, which is calculated from the measured current value by the current measurement unit in a period in which the duty ratio of the driving pulse is lower than the operation switching threshold, and the rotor rotation angle information, and outputs the calculated estimated current value as the detected current value of the estimation target phase.

A half-bridge driver circuit is configured to generate drive signals based on control signals. A processing circuit is configured to generate high side and low side control signals based on a control signal. An edge detector is configured to generate first and second signals in response to rising and falling edges in the control signal. A state machine transitions between states in response to the first and second signals, and is configured to sequentially, in response to the first signal, set the high side and low side control signals low; in response to the second signal, set the high side control signal high and the low side control signal low; in response to the first signal, set the high side and low side control signals low; and in response to the second signal, set the high side control signal low and the low side control signal high.

A power conversion apparatus includes a first inverter, a second inverter, a drive circuit to provide control signals turning on low-side switch elements in the first inverter to the low-side switch elements when a failure has occurred on a first inverter side, and provide control signals to turn on low-side switch elements in the second inverter to the low-side switch elements when a failure has occurred on a second inverter side, and a control circuit. When a failure has occurred on the second inverter side, a first power supply voltage generated on the first inverter side is supplied to the drive circuit, while when a failure has occurred on the first inverter side, a second power supply voltage generated on the second inverter side is supplied to the drive circuit.

A method for controlling a motor of a derailleur of a bicycle electronic gearshift during a displacement from an initial position (A) towards a destination position (B) includes the step of feedback controlling the current (I(t)) absorbed by the motor. A controller of an electric motor of a derailleur of a bicycle electronic gearshift is configured to carry out a feedback control of the current (I(t)) absorbed by the motor during a displacement from an initial position (A) towards a destination position (B).