Example systems and processes compare sampled values of a floating phase voltage and/or outgoing phase current of an electric motor with a corresponding reference to identify a degauss time period. Post degauss time period identification, sampled values are compared with a threshold to identify a settling time period following the degauss time period. The threshold used to identify the settling time period depends on a slope of a floating phase voltage after the degauss time period, a modulation scheme being used, and a pulse width modulation ON/OFF state of the electric motor. When the threshold comparison test is not met, it is determined whether the slope of the floating phase voltage has inverted. Based on such processing, a back-electromotive force (BEMF) zero-crossing (ZC) is detected or estimated with respect to a floating phase voltage of the electric motor.

Systems and methods for sensorless trapezoidal control of brushless DC motors provide effective high-torque startup and low speed operation without the use of Hall effect sensors or encoders during motor operation. The systems and methods also provide the ability to boost signal-to-noise ratio for motor startup and low speed operation via an augmenting supply voltage. Sampling architectures and current-dependent inductance modeling architectures for the control systems are also described.

The present disclosure relates to a motor driving method, which includes the following steps: detecting a detected voltage value between a first switch and a second switch in a driving circuit, wherein the driving circuit is configured to control the first switch and the second switch according to a switching frequency to provide a driving current to a motor device; determining a driving current according to the detected voltage value; when the driving current is less than a predetermined value, the first switch and the second switch are turned off for a detection period, wherein the length of the detection period is a fixed value; during the detection period, detecting a back electromotive force to calculate a zero crossing time of the back electromotive force; and adjusting the switching frequency according to the zero crossing time.

A method of controlling a brushless permanent magnet motor includes measuring a mains power supply voltage of the motor. The method includes determining whether the mains power supply voltage lies within a first range representative of a first country's mains power supply or a second range representative of a second country's mains power supply. The method includes advancing commutation of a winding of the motor relative to a zero-crossing of back EMF in the winding where the mains power supply voltage lies within the first range, and retarding commutation of the winding relative to a zero-crossing of back EMF in the winding where the mains power supply voltage lies within the second range.

A method for determining a rotor position of a BLDC motor with a magnetic rotor and stator having at least one exciter coil to which an exciter voltage is applied in accordance with a commutation process, comprises: interrupting the exciter voltage applied to the exciter coil, wherein the exciter voltage has a profile with at least one first section in which the profile of the exciter voltage has a non-vanishing finite gradient, wherein the exciter voltage in the first section is interrupted, and wherein at the time of interruption the exciter voltage has a value different from zero; capturing a voltage induced in the exciter coil by the magnetic rotor; restoring the exciter voltage to a value different from zero; and determining a rotor position of the rotor with respect to the exciter coil on the basis of the captured induced voltage.

A motor drive circuit includes: a PWM signal generation part configured to generate a PWM signal based on a count value of a counter; a detection part configured to detect a zero crossing of a counter electromotive voltage generated in a coil of a motor; a prediction part configured to predict an arrival timing of the zero crossing of the counter electromotive voltage; a stop part configured to stop a counting operation of the counter after a first time point going back from the arrival timing predicted by the prediction part; and a reset part configured to reset the count value at a timing at which the detection part detects the zero crossing of the counter electromotive voltage.

A control chip, a control system, and a control method for a motor are disclosed. The control chip comprises: an analog comparator comprising a first input terminal and a second input terminal, wherein the first input terminal receives a reference voltage of the motor, the second input terminal receives at least one back EMF (Electromotive Force) of the motor in turn, the analog comparator compares each of the at least one back EMF with the reference voltage in turn through a polling method, so as to produce at least one comparison result and control the motor according to the at least one comparison result. Thereby, the analog comparator is able to compare back EMF with the reference voltage without three comparators, and the cost is therefore saved.

A battery state estimating apparatus as an embodiment includes a state estimator, a power estimator, and a determiner. The state estimator estimates a state of a battery. The power estimator estimates first power amount charged/discharged by the battery within a charging/discharging period, based on the state. The determiner compares the first power amount with second power amount inputted/outputted to/from the battery within the charging/discharging period and thereby determines validity of the state.

An example apparatus as discussed herein includes a controller. The controller receives control input indicating how to control operation of a motor. In accordance with the control input, the controller controls a corresponding flow of current through each of multiple windings of the motor. According to one implementation, the controller balances positive demagnetization and negative demagnetization of each of the multiple windings in a respective control cycle.

A motor includes a stator coil, a rotor and a driving unit. The stator coil is configured to be electrified to generate a magnetic force. The rotor is rotatably coupled with the stator coil and includes a magnetic member facing the stator coil. The driving unit is electrically connected to the stator coil and outputs a driving signal to the stator coil. An electrical characteristic value of the driving signal increases in a gradual manner. The rotor outputs a motive power that is gradually increased during a process the rotor rotates from an electric angle back to a same electric angle. In addition, an activation control method for the motor and a fan are also disclosed.