A motor fault detection system is based on coupling injection of high-frequency signal. An input end of the motor is connected with the high-frequency detection signal source circuit through the coupling circuit to inject a high-frequency detection signal into the motor winding; an input end of the high-frequency detection signal source circuit is connected with an output end of the controller to control the output of the high-frequency detection signal; an output end of the response signal processing circuit is connected with an input end of the controller to send the received voltage or current response signal to the controller; and the controller judges whether the motor has a fault and the degree of the fault by analyzing the response signal after applying an excitation.

A power tool has a housing, a motor disposed within the housing, a power supply circuit for providing power to the motor, a controller circuit for controlling the power provided to the motor, and an electric static discharge (ESD) protection circuit connected to the power supply circuit and the housing. The ESD protection circuit includes a first resistor connected to the power supply circuit and the housing. The first resistor may be a high impedance resistor. The ESD protection circuit may also have a first capacitor connected in parallel to the first resistor, a second resistor connected in series to the first resistor, and a second capacitor connected in series to the first capacitor and in parallel to the second resistor.

A power tool has a housing, a motor disposed within the housing, a power supply circuit for providing power to the motor, a controller circuit for controlling the power provided to the motor, and an electric static discharge (ESD) protection circuit connected to the power supply circuit and the housing. The ESD protection circuit includes a first resistor connected to the power supply circuit and the housing. The first resistor may be a high impedance resistor. The ESD protection circuit may also have a first capacitor connected in parallel to the first resistor, a second resistor connected in series to the first resistor, and a second capacitor connected in series to the first capacitor and in parallel to the second resistor.

A load protection system and a method of protecting a load. The load protection system includes a PLC transmitter module and a PLC receiver module, which are configured to communicate a plurality of bits of data, each bit transmitted near a zero-crossing of a voltage on the power lines supplying power to the load, in the form of a high frequency burst of pulses. The pulses are structured in two patterns. The first pattern serves to identify the start of the second pattern, and the second pattern includes the data. The first pattern is unique and not represented within the second pattern. The load may be a motor, and the data may include a parameter value representing a parameter of the motor.

An axial field rotary energy device has a PCB stator panel assembly between rotors with an axis of rotation. Each rotor has a magnet. The PCB stator panel assembly includes PCB panels. Each PCB panel can have layers, and each layer can have conductive coils. The PCB stator panel assembly can have a thermally conductive layer that extends from an inner diameter portion to an outer diameter portion thereof.

An axial field rotary energy device has a PCB stator panel assembly between rotors with an axis of rotation. Each rotor has a magnet. The PCB stator panel assembly includes PCB panels. Each PCB panel can have layers, and each layer can have conductive coils. The PCB stator panel assembly can have a thermally conductive layer that extends from an inner diameter portion to an outer diameter portion thereof. Each PCB panel comprises discrete, PCB radial segments that are mechanically and electrically coupled together to form the respective PCB panels.

An axial field rotary energy device has a PCB stator panel assembly between rotors with an axis of rotation. Each rotor has a magnet. The PCB stator panel assembly includes PCB panels. Each PCB panel can have layers, and each layer can have conductive coils. The PCB stator panel assembly can have a thermally conductive layer that extends from an inner diameter portion to an outer diameter portion thereof. Each PCB panel comprises discrete, PCB radial segments that are mechanically and electrically coupled together to form the respective PCB panels.

An axial field rotary energy device with a PCB stator having interleaved PCBs is disclosed. The device can include rotors that have magnets and an axis of rotation. A stator assembly can be located axially between the rotors to operate electrical phases. The stator assembly can include PCB panels. Each PCB panel can have layers, and each PCB panel can be designated to one of the electrical phases. Each electrical phase of the stator assembly can be provided by a plurality of the PCB panels. In addition, the PCB panels for each electrical phase can be axially spaced apart from and intermingled with each other.

An axial field rotary energy device can include rotors having magnets and an axis of rotation. A stator assembly can be located axially between the rotors. The stator assembly can include PCB panels. Each PCB panel can have layers. Each layer can include coils. Each coil can have radial traces relative to the axis. The radial traces can include non-linear radial traces coupled by arch traces that are transverse to the non-linear radial traces.

A thyristor starter is configured to accelerate a synchronous machine from a stop state to a predetermined rotation speed by sequentially performing a first mode of performing commutation of an inverter by intermittently setting DC output current of a converter to zero and a second mode of performing commutation of the inverter by induced voltage of the synchronous machine. The thyristor starter is further configured to raise induced voltage in proportion to the rotation speed of the synchronous machine by keeping field current constant and to suppress rise of the induced voltage by reducing the field current after the induced voltage reaches a first voltage value, in the first mode.