Abstract: The permanent magnet brushless motor permits dynamic change of output characteristics by varying the positional relationships of rotor components, with respect to each other and with respect to the stator, to progressively effect field weakening with increasing speeds. The force required to impart the limited range of motion involved is transmitted to the rotor component by way of bearings and/or an actuation motor, and a helical guide path is used to great advantage for constraining such movement. The wide, dynamically adjustable motor output range of the motor effectively provides the equivalent of an efficient, continuously variable transmission. High torque at low speeds, and efficient, constant power output over a wide high speed range, uniquely adapt the motor for use as the prime mover for electric/hybrid vehicles.

Abstract: Gradually increasing and decreasing the friction torque feedforward term in time, prior to and immediately following intended motion, respectively, reduces the effects of variations in Coulomb friction load in an open loop step motor system.

Abstract: An electronic circuit and software control methodology tracks motor position in a motor drive system. High power consumption position transducers, such as inductive sensors or optical encoders, can be controlled in a variable active duty cycle mode to reduce power and yet maintain motor position information while the main power is off. A lower power battery backup circuit is implemented as a secondary power source, and is automatically brought in operation when the main power supply is disabled. A dedicated control circuit operates during AC power outages, and the circuit average power can be controlled to a minimal rate, based on the rate of change of motor position. The motor can be externally driven, up to a defined limit speed, without losing its actual position information.

Abstract: The load torque applied to the shaft of a synchronous motor is estimated based upon a correlation established between load torque and a calculated integral of a drive current value, utilizing the measured current that is applied to drive the motor. The estimated load torque is used as the basis for controlling the driving current amplitude so as to achieve increased efficiency of energy utilization. Control apparatus embodies the technique, and a synchronous motor system includes such apparatus.

Abstract: The voltage at a node between a pair of series-connected windings of a synchronous or stepping motor is monitored during operation so as to detect transition voltage regions, the durations of which are indicative of the torque load on the motor and which are used as the basis for controlling the driving current amplitude so as to achieve enhanced efficiency of energy utilization. An optimum value for the duration of the transition voltage region will usually be established as a target, and adjustments will be so made as to conform subsequently detected node voltage values to those of the target.

Abstract: Phase alignment and initialization of a polyphase brushless DC motor are achieved, at standstill, by noting amplitude changes in signals from integral feedback coils while phase coils of the motor, magnetically coupled to the sensor coils, are energized at non-torque producing commutation angles.

Abstract: The recursive profile generator of a general purpose position control system relies only upon current state and target state information in generating the path of movement for the armature of the servomotor. The profile generator employs a convergent algorithm for calculating the acceleration necessary to reach each control point or target position. By ignoring previous state information, the profile generator makes the use of reduced computing power possible and readily accommodates changing target state conditions.

Abstract: A polyphase brushless DC motor has an integral automatic feedback arrangement affording excellent accuracy and a high degree of magnetic balance. The stator pole elements of the motor are identical and equidistantly spaced, and each is wound with two coils. One coil on each pole element comprises sensor circuitry; the other comprises power circuitry. As a result, all pole elements of the stator are utilized both to produce rotor drive torque and also to generate electrical signals that provide highly accurate rotor-position information.

Abstract: A polyphase brushless DC motor has an integral automatic feedback arrangement and a high degree of magnetic balance. The stator pole elements of the motor are identical and equidistantly spaced, and the coils with which they are wound are connected as pairs; the pole elements in most of the armature pairs are directly adjacent one another. The sensor means has at least two circuit legs, each being connected to paired pole elements of the stator to provide a sensor channel, the channels cooperating to provide highly accurate rotor position feedback information.