A method for fail-safe rotational speed monitoring of a sensorless three-phase drive, in which the three-phase drive is controlled in three phases with the phases U, V, W by drive electronics comprising an inverter, with the voltage signals at the three phases U, V, W being present as pulse width modulated signals, in which an output frequency of the inverter applied to the drive is determined and an actual rotational speed of the drive is determined therefrom, in which the actual rotational speed is compared with a predeterminable desired rotational speed and in which, if the actual rotational speed exceeds the desired rotational speed, the drive is switched off, the pulse width of the pulse width modulated signals being used to determine the output frequency of the inverter.

A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.

A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.

An event estimation system includes an upper device, and a lower controller device including first circuitry that acquires operation information of a control target device connected to the lower controller device, estimates a presence or absence of an abnormality based on the operation information, holds the operation information for a certain time period, and transmits, based on the presence or absence of an abnormality and to the upper device, the operation information related to the estimation of the presence or absence of the abnormality. The upper device has second circuitry that receives the operation information from the lower controller device, and operates according to the presence or absence of the abnormality, inputs, using an upper neural network model, the operation information, output event information, and estimates an event.

An event estimation system includes an upper device, and a lower controller device including first circuitry that acquires operation information of a control target device connected to the lower controller device, estimates a presence or absence of an abnormality based on the operation information, holds the operation information for a certain time period, and transmits, based on the presence or absence of an abnormality and to the upper device, the operation information related to the estimation of the presence or absence of the abnormality. The upper device has second circuitry that receives the operation information from the lower controller device, and operates according to the presence or absence of the abnormality, inputs, using an upper neural network model, the operation information, output event information, and estimates an event.

A fan assembly is provided. The fan assembly includes a fan, a motor that is coupled to the fan, and a variable frequency drive (VFD) that is coupled to the motor. The motor includes a maximum rated speed that is greater than a maximum structural speed limit of the fan, and the VFD includes a current output limit configured to limit an operational speed of the motor to be less than or equal to the maximum structural speed limit of the fan.

A fan assembly is provided. The fan assembly includes a fan, a motor that is coupled to the fan, and a variable frequency drive (VFD) that is coupled to the motor. The motor includes a maximum rated speed that is greater than a maximum structural speed limit of the fan, and the VFD includes a current output limit configured to limit an operational speed of the motor to be less than or equal to the maximum structural speed limit of the fan.

A system and method for shaping the trajectory of a motion command to reduce the effects of a load on performance of a motor dynamically modifies the motion profile in real time to limit the reference signals in the motion profile to feasible commands. A load observer determines an estimated disturbance acceleration. The estimated disturbance acceleration includes the dynamics of the controlled load and is used to modify a maximum and a minimum limit for the acceleration reference. The acceleration limits are, in turn, used to determine velocity limits. The motion profile and modified acceleration and velocity limits are provided to a state filter which determines a new motion profile for use by the motor drive to control operation of a motor and to control the load connected to the motor.

A system and method for shaping the trajectory of a motion command to reduce the effects of a load on performance of a motor dynamically modifies the motion profile in real time to limit the reference signals in the motion profile to feasible commands. A load observer determines an estimated disturbance acceleration. The estimated disturbance acceleration includes the dynamics of the controlled load and is used to modify a maximum and a minimum limit for the acceleration reference. The acceleration limits are, in turn, used to determine velocity limits. The motion profile and modified acceleration and velocity limits are provided to a state filter which determines a new motion profile for use by the motor drive to control operation of a motor and to control the load connected to the motor.

A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.