Abstract: A method for controlling a brushless electric motor including a rotor, a sense element with a plurality of magnetic pole pairs, and first and second sensors mounted less than or equal to 120 electrical degrees apart with sensing planes oriented perpendicular to an adjacent surface of the sense element and perpendicular to a movement direction of the sense element relative to the sensors, wherein one of a) the sense element and b) the first and second sensors is mounted in a fixed relationship with the rotor, the method including measuring magnetic flux of the plurality of magnetic pole pairs using the first and second sensors and outputting a corresponding measurement signal for each at least one first and second sensor, determining a rotational position of the rotor based on the measurement signals, and controlling the motor based on the determined rotor position.

Abstract: An inexpensive and accurate device for sensing rotor position and detecting rotational speed over a broad range of speeds in an electric motor includes a sense ring magnet and two analog Hall effect sensors. The sense ring is magnetized in an alternating north-south fashion with a number of poles that correspond to a number of motor field poles. The Hall effect sensors are placed so that they measure magnetic flux tangential to the sense ring. The Hall effect sensors are preferably located at a distance from the sense ring where the Hall effect sensor output waveforms are substantially triangular, with a highly linear portion centered at zero flux between the minimum and maximum waveform peaks. The linear portions of the waveforms are decoded using an A/D converter and control software to provide an accurate measure of the rotor position.

Abstract: An inexpensive and accurate device for sensing rotor position and detecting rotational speed over a broad range of speeds in an electric motor includes a sense ring magnet and two analog Hall effect sensors. The sense ring is magnetized in an alternating north-south fashion with a number of poles that correspond to a number of motor field poles. The Hall effect sensors are placed so that they measure magnetic flux tangential to the sense ring. The Hall effect sensors are preferably located at a distance from the sense ring where the Hall effect sensor output waveforms are substantially triangular, with a highly linear portion centered at zero flux between the minimum and maximum waveform peaks. The linear portions of the waveforms are decoded using an A/D converter and control software to provide an accurate measure of the rotor position.

Abstract: An electric motor assembly has an inner-rotor configuration including a hollow space within the rotor hub. The hollow space houses at least part of a brake for providing a braking force between a rotor and a stator of the electric motor. The brake can be configured to provide a braking force when no power is flowing to the electric motor, and can have an outer diameter less than an inner diameter of the rotor.

Abstract: A drive system for a brushless DC motor uses pulse width modulation, and phase timing advancement to maintain a constant power output during high speed use. The arrangement is well suited for driving a brushless motor in an electric vehicle and the like.