A system is for a machine having an alternating current (AC) power source with a first side and a second side, one or more windings, an AC polarity detector, a Hall effect device, two or more pairs of power switches, and a motor controller. The motor controller determines which of the power switches to open or close to obtain a direction of current flow through the one or more windings based on signals from the AC polarity detector and the Hall effect device.

A system is for a machine having an alternating current (AC) power source with a first side and a second side, one or more windings, an AC polarity detector, a Hall effect device, two or more pairs of power switches, and a motor controller. The motor controller determines which of the power switches to open or close to obtain a direction of current flow through the one or more windings based on signals from the AC polarity detector and the Hall effect device.

A current limit protecting system and method of a motor pre-driver are provided. A current limiting circuit detects a current of a resistor that is connected to a motor, and then compares the current of the resistor with a current threshold to output a current comparing signal. When a controller circuit determines that the current of the resistor is larger than the current threshold according to the current comparing signal, and a working period of a first signal of a first node or a working period of a second signal of a second node of the motor reaches a preset value, a first high-side switch and a second high-side switch are turned off, and a first low-side switch and a second low-side switch are alternately turned on. As a result, a temperature of the motor generally reduces.

A control system includes a motor controller coupled to a brushless direct current motor. The motor controller determines a first start time and a first duration for a first pulse and a second start time and a second duration for a second pulse relative to a commutation cycle of the motor. The motor controller energizes a winding of the motor with the first pulse and the second pulse within the commutation cycle.

A motor controller is configured to stabilize the motor current. The motor controller is used for driving a motor. The motor controller comprises a switch circuit, a control unit, and a phase detecting unit. The phase detecting unit generates a phase signal to the control unit for switching phases. The phase signal sequentially generates a first, second, third, fourth, fifth and sixth time interval. The first to sixth time intervals correspond to first to sixth phases, respectively. The motor controller further comprises a first driving time for driving the motor in the fifth phase, where the first driving time is related to the first time interval. The motor controller further comprises a second driving time for driving the motor in the sixth phase, where the second driving time is related to the second time interval.

An electrical combination, a tool system, an electric motor, a battery pack, and operating and manufacturing methods. The tool may include a tool housing, a motor supported by the tool housing, the motor having a nominal outer diameter of up to about 80 millimeters (mm), the motor being operable to output at least about 2760 watts (W), and a tool terminal electrically connected to the motor; a battery pack including a pack housing defining a volume of the battery pack, the volume being up to about 5.2×10.sup.6 cubic millimeters (mm.sup.3), battery cells supported by the pack housing, the battery cells being electrically connected and having a nominal voltage of up to about 80 volts (V), and a pack terminal electrically connectable to the tool terminal to transfer current between the battery pack and the tool; and a controller operable to control the transfer of current.

An electrical combination, a tool system, an electric motor, a battery pack, and operating and manufacturing methods. The tool may include a tool housing, a motor supported by the tool housing, the motor having a nominal outer diameter of up to about 80 millimeters (mm), the motor being operable to output at least about 2760 watts (W), and a tool terminal electrically connected to the motor; a battery pack including a pack housing defining a volume of the battery pack, the volume being up to about 5.2×10.sup.6 cubic millimeters (mm.sup.3), battery cells supported by the pack housing, the battery cells being electrically connected and having a nominal voltage of up to about 80 volts (V), and a pack terminal electrically connectable to the tool terminal to transfer current between the battery pack and the tool; and a controller operable to control the transfer of current.

A motor unit comprises a driving circuit, a control unit, an analog-to-digital converter, a voltage divider, and a voltage converter. The driving circuit is coupled to a motor for driving the motor. The control unit is configured to generate a plurality of control signals to control the driving circuit. The analog-to-digital converter receives an output voltage for generating a digital signal to the control unit. The voltage divider receives an input voltage for generating a first voltage. The voltage converter converts a power supply voltage into the input voltage. The motor unit may execute a prevention mechanism to avoid misjudging the digital signal. The motor unit may be applied to a high-voltage configuration.

A motor unit comprises a driving circuit, a control unit, an analog-to-digital converter, a voltage divider, and a voltage converter. The driving circuit is coupled to a motor for driving the motor. The control unit is configured to generate a plurality of control signals to control the driving circuit. The analog-to-digital converter receives an output voltage for generating a digital signal to the control unit. The voltage divider receives an input voltage for generating a first voltage. The voltage converter converts a power supply voltage into the input voltage. The motor unit may execute a prevention mechanism to avoid misjudging the digital signal. The motor unit may be applied to a high-voltage configuration.

A brake control system of a motor is provided. When a control circuit intends to brake the motor, the control circuit controls a driver circuit to turn off a first high-side switch and a second high-side switch, and to fully turn on the first low-side switch and the second low-side switch, for a period of time. Then, the control circuit controls the driver circuit to turn off one of the first low-side switch and the second low-side switch, and to continually turn on the other one of the first low-side switch and the second low-side switch, for a period of time. Then, the control circuit controls the driver circuit to turn off the other one of the first low-side switch and the second low-side switch, and to turn on the one of the first low-side switch and the second low-side switch, for a period of time.