A control system may include a processor that may receive a first dataset associated with a current received at a load device coupled to a relay device. The processor may also determine harmonics data associated with the current and determine a switching profile to control moving a first armature of three armatures in the relay device based on the harmonics data. The switching profile is configured to control movement of the first armature between a first position and a second position, and wherein the switching profile comprises a firing angle for moving the first armature with respect to an electrical waveform, a second armature, and a third armature. The processor may then control a current provided to a relay coil of the relay device based on the switching profile, such that the relay coil causes the first armature to move.

A contactless power supply and motor control system includes a pulse width modulator, a rotary transformer, a demodulator circuit, a motor driver, and a motor. The pulse width modulator supplies a first pulse width modulated (PWM) signal that has a duty cycle and a first amplitude. The rotary transformer receives the PWM signal. The secondary winding is rotatable relative to the primary winding and supplies a second PWM signal having the duty cycle and a second amplitude. The demodulator circuit is rotatable with the secondary winding and supplies a demodulated direct current (DC) voltage having a DC voltage amplitude. The motor driver is rotatable with the secondary winding and the demodulator circuit and controllably supplies motor current. The motor receives the motor current and rotates at a rotational speed.

A motor system can include a motor, the motor including at least a rotor, and a controller configured to operate the motor. The controller can be configured to perform operations for operating the motor. The operations can include determining an initial estimated rotor angle, determining one or more estimated currents defined by an estimated rotating reference frame based at least in part on the estimated rotor angle, obtaining one or more current measurements of one or more measured currents respective to the one or more estimated currents, determining one or more current errors based at least in part on a subtractive combination of the one or more estimated currents and the one or more measured currents, determining one or more rotor flux estimates based at least in part on the one or more current errors, the one or more rotor flux estimates comprising at least an estimated δ-directed rotor flux vector, and determining an estimated rotor speed based at least in part on an integral of the estimated δ-directed rotor flux vector.

A power tool, such as a drilling power tool, configured to perform an easy hole start operation upon actuation of a trigger. When the trigger is actuated, the motor is driven at a low speed value. The motor speed is increased to a second speed value during a predetermined time threshold and then driven at the second speed value until the trigger is no longer actuated. In some embodiments, the easy hole start operation may be implemented by an easy hole start switch. In some embodiments, if the easy hole start operation persists for a time greater than a predetermined time threshold, then the motor will shut off.

A power tool, such as a drilling power tool, configured to perform an easy hole start operation upon actuation of a trigger. When the trigger is actuated, the motor is driven at a low speed value. The motor speed is increased to a second speed value during a predetermined time threshold and then driven at the second speed value until the trigger is no longer actuated. In some embodiments, the easy hole start operation may be implemented by an easy hole start switch. In some embodiments, if the easy hole start operation persists for a time greater than a predetermined time threshold, then the motor will shut off.

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.

Methods and power tools for sensorless motor control. One embodiment provides a method for automatic control switching for driving a sensorless motor (150) of a power tool (100). The method includes determining, using a motor controller (224), a first load point based on user inputs (232) and determining, using the motor controller (224), a first motor control technique corresponding to the first load point. The method also includes driving the motor (150) based on the first motor control technique. The method further includes determining, using the motor controller (224), a change from the first load point to a second load point and determining, using the motor controller (224), a second motor control technique corresponding to the second load point. The method includes driving the motor (150) based on the second motor control technique.

Examples include a method for controlling a synchronous motor using a variable speed drive. The motor includes a permanent magnet rotor generating a magnetic flux. The method includes applying a predefined electrical command signal to the motor and estimating a motor speed in response to the applying of the predefined electrical command signal. The method also includes reaching a desired estimated motor speed and, in response to reaching the desired estimated motor speed, estimating a parameter related to the magnetic flux of the permanent magnet rotor. The method further includes recording the estimated parameter.

A soft-start circuit which can be applied to a motor controller is provided. The soft-start circuit comprises a controller, a counting unit, a digital-to-analog converter, a current detecting unit, and a comparator. The soft-start circuit uses a plurality of current limit values so as to achieve a maximum output power and prevent damage to a motor coil.