An estimation device includes a phase current determination unit, a time difference calculation unit, and an estimation unit. The phase current determination unit performs a determination process for determining values of phase currents based on the value of the bus current detected by a bus current detection unit and states of gate pulse signals. The time difference calculation unit calculates a difference between a detection time of the bus current used in a previous determination process and a detection time of the bus current used in a present determination process. The estimation unit estimates at least one of a position and a speed of an AC motor based on the values of the phase currents determined by the phase current determination unit and the difference calculated by the time difference calculation unit.

A commutation error compensation method for an electric motor includes: when a rotor, that has not been corrected, in an electric motor rotates in a set direction, collecting a position signal and a three-phase current signal of the rotor, wherein the position signal of the rotor represents the rotation angle of the rotor; filtering processing on the three-phase current signal to obtain a fundamental component of the three-phase current signal, and determining a position error compensation signal of the electric motor on the basis of the fundamental component of the three-phase current signal; determining an ideal phase interval of the rotor according to the position error compensation signal and the position signal of the rotor; and determining an adjustment method for the rotor of the electric motor according to the ideal phase interval of the rotor, and commutating the rotor of the electric motor according to the adjustment method.

A motor controller comprises a switch circuit and a control unit. The switch circuit is coupled to a motor for driving the motor. The control unit is configured to generate a control signal to control the switch circuit. The motor controller is configured to generate a current signal and a voltage signal. When a current phase of the current signal is at a predetermined crossing phase, the motor controller calculates a difference value between the current phase of the current signal and a voltage phase of the voltage signal, where the motor controller is configured to control the difference value. The motor controller may stabilize the motor and avoid noise by modulating the difference value. The motor controller may modulate the difference value, such that the difference value is equal to a predetermined phase difference.

A motor controller comprises a switch circuit and a control unit. The switch circuit is coupled to a motor for driving the motor. The control unit generates a control signal to control the switch circuit. The motor controller determines a non-excitation time. When the motor is in a locked state, the motor controller enables the non-excitation time to be a variable value. The motor controller utilizes the non-excitation time to achieve a lock protection function. The motor controller determines whether the motor is in the locked state by detecting a rotor speed or a rotor temperature. Moreover, the motor controller further comprises a driving signal, where the driving signal has the non-excitation time.

A motor control system includes a reference current generator that generates a reference current based on a command, a motor voltage providing device that generates a phase voltage based on the reference current, a high frequency voltage, and a feedback current and provides a motor with the phase voltage, and a high frequency voltage generator that generates the high frequency voltage corresponding to a magnitude of voltage generated based on the reference current and the feedback current.

A motor control apparatus includes a detection unit configured to detect an actual rotation position of a motor, a control unit configured to provide position feedback control on the motor so that the detected actual rotation position sequentially approaches a plurality of target rotation positions, and a processing unit configured to perform, before the position feedback control starts, processing to make an initial position deviation fall within a predetermined range, the initial position deviation being a difference between the actual rotation position and a first target rotation position of the plurality of target rotation positions.

A motor control apparatus includes a detection unit configured to detect an actual rotation position of a motor, a control unit configured to provide position feedback control on the motor so that the detected actual rotation position sequentially approaches a plurality of target rotation positions, and a processing unit configured to perform, before the position feedback control starts, processing to make an initial position deviation fall within a predetermined range, the initial position deviation being a difference between the actual rotation position and a first target rotation position of the plurality of target rotation positions.

A method for determining a position of a rotor of a brushless direct current (BLDC) motor at standstill. The method includes providing a plurality of current pulses to a plurality of windings of the BLDC motor while the rotor of the BLDC motor is at a standstill position. The method further includes measuring a plurality of times that it takes for the plurality of current pulses to reach a threshold for respective ones of the plurality of windings. A first position corresponding to a shortest time of the plurality of times is determined. A position detection value is determined based on the shortest time and based on times corresponding to positions that are adjacent to the first position. A position of the rotor at the standstill position is determined based on the position detection value and an interpolation function.

A test and measurement instrument includes one or more sensors configured to measure a mechanical position of a synchronous machine driven by analog three-phase signals, a converter to determine an instantaneous electrical angle from the measured mechanical position, a transform configured to generate DQ0 signals based on the instantaneous electrical angle, and a vector generator structured to produce a resultant vector from the DQ0 signals. Methods are also described.

A test and measurement instrument includes one or more sensors configured to measure a mechanical position of a synchronous machine driven by analog three-phase signals, a converter to determine an instantaneous electrical angle from the measured mechanical position, a transform configured to generate DQ0 signals based on the instantaneous electrical angle, and a vector generator structured to produce a resultant vector from the DQ0 signals. Methods are also described.