Abstract: Systems, apparatus and methods are presented for multiphase inverter control in which PWM switching control signals are generated for operating inverter switching devices according to current feedback values, and a given inverter phase is identified in a given PWM switching cycle having the lowest low side duty cycle on-time. A phase current feedback value is selectively computed for the identified phase at least partially according to the low side current shunt voltage values corresponding to other output phases, and the phase current feedback values are updated with the computed phase current feedback value and the low side current shunt voltage values of the remaining output phases to provide feedback for closed loop PWM switching control.

Abstract: A motor control circuit includes a processor configured to calculate a plurality of motor impedances from measurements of an excitation voltage on a power bus to a motor and measurements of a plurality of currents through the motor resulting from the excitation voltage, and the processor configured to calculate individual winding inductances in the motor, based on the measured motor impedances, and configured to determine whether there is an inter-turn winding fault based on the calculated individual winding inductances.

Abstract: A motor driver combination for controlling a travelling wave motor includes a pre-driver including a microcontroller unit (MCU) chip including a plurality of high-resolution pulse width modulation (HRPWM) generators providing a frequency resolution better than ten Hz. A digital bus is for transferring digital words received from a controller in a servo and velocity control block to the HRPWM generators, where the digital words provide travelling wave motor operating performance information from the motor during its operation. A clock oscillator providing an accuracy of at least eighty (80) parts per million (ppm) is coupled to or provided by the MCU chip for each of the high-resolution PWM generators. A motor driver includes a plurality of power drivers for providing phased outputs for driving the travelling wave motor including a plurality of inputs coupled to outputs of the plurality of HRPWM generators. The travelling wave motor can be an ultrasonic motor.

Abstract: An apparatus for monitoring speaker cone displacement in an audio speaker includes: (a) an electromagnetic coil structure; (b) a ferrous core structure; the ferrous core structure and the electromagnetic coil structure being mounted with the speaker to effect variable electromagnetic coupling between the ferrous core structure and the electromagnetic coil structure as the speaker cone moves; (c) a signal injecting circuit coupled with the electromagnetic coil structure for injecting a predetermined input signal into the electromagnetic coil structure; and (d) a signal monitoring circuit coupled with the electromagnetic coil structure; the signal monitoring circuit receiving an output signal from the electromagnetic coil structure and generating an indicating signal based upon the output signal; at least one signal characteristic of the indicating signal being related with the cone displacement.

Abstract: Disclosed are methods and apparatus for isolating and driving a power supply or power amplifier circuit. The circuits and methods provide for using a modulated PWM input signal and its complement to drive one or more core-less transformers providing an isolated power supply circuit output signal reproducing the PWM input signal. Preferred methods of the invention are disclosed in which steps for receiving and modulating a PWM input signal and its complement are included. In further steps, the modulated PWM signal and its complement control an isolated output driver to provide a power supply circuit output signal reproducing the PWM input signal. Embodiments of the invention are disclosed in which a circuit is configured for receiving a PWM input signal, providing isolation, and outputting a PWM output signal. The circuits include modulators for modulating a PWM input signal and its complement.

Abstract: An apparatus for driving a speaker that includes an audio element moved by drive signals applied to the speaker, the speaker having a resistance and a force factor, includes: (a) an amplifier generating drive signals and having an output coupled with the speaker and an input; and (b) a feedback circuit coupling the speaker with the input and including: (1) a monitor coupled with the speaker and generating indicating signals representing selected speaker signal parameters; and (2) a processor coupled with the monitor, with the input and with a signal source providing received signals. The processor combines the received signals with the indicating signals to generate a modified signal for use by the amplifier in generating drive signals. The modified signal includes at least one factor relating to velocity of the audio element. Efficiency of the speaker is improved by inversely varying the resistance and the force factor with respect to each other.