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.

An automated counterbalance system includes a crossing gate mechanism with an electric motor, a sensing device and a motor control unit, a crossing gate with a crossing gate arm and one or more counterweights, wherein the crossing gate arm is operated by the crossing gate mechanism, wherein the at least one sensing device is configured to monitor an electrical characteristic of the electric motor, and wherein the motor control unit comprises at least one processor and is configured to determine a counterbalance of the crossing gate based on the electrical characteristic of the electric motor and a movement of the crossing gate arm.

An automated counterbalance system includes a crossing gate mechanism with an electric motor, a sensing device and a motor control unit, a crossing gate with a crossing gate arm and one or more counterweights, wherein the crossing gate arm is operated by the crossing gate mechanism, wherein the at least one sensing device is configured to monitor an electrical characteristic of the electric motor, and wherein the motor control unit comprises at least one processor and is configured to determine a counterbalance of the crossing gate based on the electrical characteristic of the electric motor and a movement of the crossing gate arm.

Systems and methods for voltage regulation of high voltage direct current systems are provided. In certain embodiments, a system includes a generator that generates alternating current (AC) voltage. The system further includes a power converter that converts the AC voltage into regulated direct current (DC) voltage. Also, the system includes a voltage regulator. In additional embodiments, the voltage regulator includes an AC voltage regulator that regulates the AC voltage generated by the generator. Also, the voltage regulator includes a DC voltage regulator that regulates the DC voltage produced by the power converter. Moreover, the voltage regulator includes a regulator selector that selectively activates one of the AC voltage regulator and the DC voltage regulator based on a current from the power converter and at least one of a voltage of the generator and a voltage of the power converter.

Methods and apparatus for open loop startup of a three-phase motor that reduces acoustic noise. During rotor alignment of the motor, there is a maximum level for a phase current to the motor. After the rotor alignment, open loop motor startup is performed during which the phase current has a first slope. At a selected time, such as when a frequency of the phase current reaches a first threshold, the phase current transitions to a second slope.

A stator defines multiple stator poles with associated electrical windings. A rotor includes multiple rotor poles. The rotor is movable with respect to the stator and defines, together with the stator, a nominal gap between the stator poles and the rotor poles. The rotor poles includes a magnetically permeable pole material. The rotor also includes a series of frequency programmable flux channels (FPFCs). Each FPFC includes a conductive loop surrounding an associated rotor pole. The stator and the rotor are arranged such that the electrical windings in the stator induce an excitement current within at least one of the FPFCs during start-up.

A control device 60 includes: a PWM generation unit 63 that outputs a PWM drive signal to an inverter 40; and a torque limiting unit that outputs a post-limitation torque command to the PWM generation unit 63 based on a torque command from a higher-order control unit and a motor temperature. The torque limiting unit includes: a torque limiting factor calculation unit 61 that calculates a torque limiting factor based on the motor temperature; and a post-limitation torque calculation unit 62 that outputs the post-limitation torque command to the PWM generation unit 63 based on the torque command and the torque limiting factor. The torque limiting factor calculation unit 61 limits an output torque based on the motor temperature in a case where the motor temperature is higher than a predetermined temperature, and limits a torque to make the torque change more gently in a case where a rate of change over time in the motor temperature is larger than a predetermined value as compared with a case where the rate of change over time is equal to or smaller than the predetermined value.

A power tool includes a motor, a switch, a driver circuit, an operating element, and a controller. The motor includes a multi-phase winding. The driver circuit has multiple power elements and is configured to change a rotational state of the motor. The operating element has a first operating state and a second operating state, where a strength of an effective magnetic field of the multi-phase winding when the operating element is in the first operating state is less than a strength of an effective magnetic field of the multi-phase winding when the operating element is in the second operating state. The controller is configured to control conduction manners of the multiple power elements in the driver circuit according to an operating state of the operating element, so as to adjust the strength of the effective magnetic field of the multi-phase winding and change the rotational state of the motor.

A power tool includes a motor, a switch, a driver circuit, an operating element, and a controller. The motor includes a multi-phase winding. The driver circuit has multiple power elements and is configured to change a rotational state of the motor. The operating element has a first operating state and a second operating state, where a strength of an effective magnetic field of the multi-phase winding when the operating element is in the first operating state is less than a strength of an effective magnetic field of the multi-phase winding when the operating element is in the second operating state. The controller is configured to control conduction manners of the multiple power elements in the driver circuit according to an operating state of the operating element, so as to adjust the strength of the effective magnetic field of the multi-phase winding and change the rotational state of the motor.

A controller is adapted to be coupled to a brushless direct current (DC) motor and includes an analog-to-digital converter (ADC), a computing device, and a driver. The ADC is configured to receive an analog back electromotive force (BEMF) waveform from the brushless DC motor and sample the analog BEMF waveform to produce a digital BEMF waveform. The computing device is coupled to the ADC and is configured to receive the digital BEMF waveform and determine a position and a speed of the rotor based on the digital BEMF waveform. The driver is coupled to the ADC and the computing device and is configured to receive the position and the speed of the rotor and provide a drive signal based on the position and the speed of the rotor of the brushless DC motor.