Abstract: An apparatus includes a sensorless field-oriented control (FOC) motor controller. The motor controller includes a pulse width modulation (PWM) controller configured to generate PWM signals and to provide the PWM signals to an inverter. The motor controller also includes an angle sampler configured to receive a commanded voltage angle signal and to provide the commanded voltage angle signal as an output signal in response to a triggering event. The triggering event is based on a voltage or a current associated with an input or an output of the inverter. The motor controller further includes a first combiner configured to combine (i) a feed-forward voltage angle signal and (ii) a second signal based on the output signal. The first combiner is configured to generate the commanded voltage angle signal. In addition, the motor controller includes a second combiner configured to combine a feed-forward voltage amplitude signal and the second signal.

Abstract: An apparatus includes a sensorless field-oriented control (FOC) motor controller. The motor controller includes a pulse width modulation (PWM) controller configured to generate PWM signals and to provide the PWM signals to an inverter. The motor controller also includes an angle sampler configured to receive a commanded voltage angle signal and to provide the commanded voltage angle signal as an output signal in response to a triggering event. The triggering event is based on a voltage or a current associated with an input or an output of the inverter. The motor controller further includes a first combiner configured to combine (i) a feed-forward voltage angle signal and (ii) a second signal based on the output signal. The first combiner is configured to generate the commanded voltage angle signal. In addition, the motor controller includes a second combiner configured to combine a feed-forward voltage amplitude signal and the second signal.

Abstract: A method and apparatus for predicting the peak voltage at the load end of a power transmission cable having a power supply end and a load end, where direct measurement at the load end is not practical. The method samples the current and voltage waveforms at the power supply end of the cable. The current waveform is used to estimate a current function which includes a full width at half maximum and adjustments for cable reactive current, distortions, and load. The product of the current function and a peak voltage sample from the power supply end is an estimate of the peak voltage at the load end. The method and apparatus have been applied to oil well logging where one or more logging tools are lowered at the end of a transmission cable into an oil well and it is desirable to predict peak voltage at the tools to ensure proper tool performance. An important improvement is a more accurate current function which compensates for capacitive current flow in the cable and includes a quadratic term.

Abstract: A method and apparatus for predicting the peak voltage at the load end of a power transmission cable having a power supply end and a load end, where direct measurement at the load end is not practical. The method samples the current and voltage waveforms at the power supply end of the cable. The current waveform is used to estimate a current function which includes a full width at half maximum approximation adjusted as required for load, cable type, and cable length. The product of the current function and a peak voltage sample from the power supply end is an estimate of the peak voltage at the load end. The method and apparatus have been applied to oil well logging where one or more logging tools are lowered at the end of a transmission cable into an oil well and it is desirable to predict peak voltage at the tools to ensure proper tool performance.