Abstract: A retina image template matching method is based on the registration and comparison between the images captured with portable low-cost fundus cameras (e.g., a consumer grade camera typically incorporated into a smartphone or tablet computer) and a baseline image. The method solves the challenges posed by registering small and low-quality retinal template images captured with such cameras. Our method combines dimension reduction methods with a mutual information (MI) based image registration technique. In particular, principle components analysis (PCA) and optionally block PCA are used as a dimension reduction method to localize the template image coarsely to the baseline image, then the resulting displacement parameters are used to initialize the MI metric optimization for registration of the template image with the closest region of the baseline image.

Abstract: For improving Maximum Torque per Amps (MTPA) control, a method generates an offline MTPA curve based on an autotune test for a motor, which is used as offline MTPA control in order to run a motor at a high efficiency operation point. Another online method generates a search zone for the MTPA curve for a given torque point. The search zone includes an upper D-axis reference current and a lower D-axis reference current for the given torque point. The method iteratively modifies a D-axis reference current between the upper D-axis reference current and the lower D-axis reference current of the search zone. The method modifies a Q-axis reference current to output the given torque. The method updates a corresponding current pair of the given torque point to the modified D-axis reference current and the modified Q-axis reference current with a lowest current amplitude to improve MTPA control of the motor.

Abstract: Power conversion systems and a controller thereof include a processing system that generates inverter switching control signals at a switching frequency, and transitions the switching frequency from a starting frequency to a target frequency over an integer number N blocks. The individual blocks include an integer number M subblocks with a starting frequency subblock in which the processing system generates the switching control signals at the starting frequency, and a target frequency subblock in which the processing system generates the switching control signals at the target frequency. The processing system operates the inverter at multiple demanded voltage values for multiple characterized switching frequencies, measures and records a corresponding inverter output current value for each of the demanded voltage values, creates and stores a lookup table for adjusted demand voltages at each of the characterized switching frequencies, and operate the inverter according to the adjusted demand voltages.

Abstract: Power conversion systems and a controller thereof include a processing system that generates inverter switching control signals at a switching frequency, and transitions the switching frequency from a starting frequency to a target frequency over an integer number N blocks. The individual blocks include an integer number M subblocks with a starting frequency subblock in which the processing system generates the switching control signals at the starting frequency, and a target frequency subblock in which the processing system generates the switching control signals at the target frequency. The processing system operates the inverter at multiple demanded voltage values for multiple characterized switching frequencies, measures and records a corresponding inverter output current value for each of the demanded voltage values, creates and stores a lookup table for adjusted demand voltages at each of the characterized switching frequencies, and operate the inverter according to the adjusted demand voltages.

Abstract: Power conversion systems and a controller thereof include a processing system that generates inverter switching control signals at a switching frequency, and transitions the switching frequency from a starting frequency to a target frequency over an integer number N blocks. The individual blocks include an integer number M subblocks with a starting frequency subblock in which the processing system generates the switching control signals at the starting frequency, and a target frequency subblock in which the processing system generates the switching control signals at the target frequency. The processing system operates the inverter at multiple demanded voltage values for multiple characterized switching frequencies, measures and records a corresponding inverter output current value for each of the demanded voltage values, creates and stores a lookup table for adjusted demand voltages at each of the characterized switching frequencies, and operate the inverter according to the adjusted demand voltages.

Abstract: Power conversion systems and a controller thereof includes a first processing system that computes phase references for respective phase lines of an inverter according to a feedback value, a setpoint value, and a scaling factor to emulate a scaled frequency that is less than a switching frequency, and a second processing system that generates a carrier waveform having the switching frequency, receives the phase reference from the first processing system for each inverter phase line, and compares each phase reference with the carrier waveform to generate pulse width modulated switching control signals for switching devices of the inverter.

Abstract: For calculating load resistance, a pulse generation module drives a pulse width modulation (PWM) inverter in response to a control voltage. The PWM inverter includes a U phase pole, a V phase pole, and a W phase pole. Each U, V, and W phase pole includes an upper pole device and a lower pole device. The PWM inverter turns off the U phase pole, turns on the W upper pole device, turns off the W lower pole device, and applies the control voltage to the V upper pole device and the V lower pole device. A forward drop correction module corrects the control voltage based on a feedforward compensation voltage determined from a forward voltage drop. A load resistance module calculates a load resistance for a load based on an average control voltage, an average bus voltage, and an average load feedback current.

Abstract: Power converters, controllers, methods and non-transitory computer readable mediums are presented, in which a processor operates a switching rectifier in a first mode to regulate a DC bus voltage signal using rectifier switching control for motoring rectifier operation when the measured DC bus voltage value is less than or equal to a first threshold value, operates the switching rectifier in a second mode to regulate the DC bus voltage signal using rectifier switching control for regenerative rectifier operation when the measured DC bus voltage value is greater than the first threshold value and less than or equal to a higher second threshold value, and operates an inverter in a third mode to regulate the DC bus voltage signal using inverter acceleration/deceleration control when the measured DC bus voltage value is greater than the second threshold value.

Abstract: For calculating load resistance, a pulse generation module drives a pulse width modulation (PWM) inverter in response to a control voltage. The PWM inverter includes a U phase pole, a V phase pole, and a W phase pole. Each U, V, and W phase pole includes an upper pole device and a lower pole device. The PWM inverter turns off the U phase pole, turns on the W upper pole device, turns off the W lower pole device, and applies the control voltage to the V upper pole device and the V lower pole device. A forward drop correction module corrects the control voltage based on a feedforward compensation voltage determined from a forward voltage drop. A load resistance module calculates a load resistance for a load based on an average control voltage, an average bus voltage, and an average load feedback current.

Abstract: A power conversion system can be implemented to actively control a load while compensating for reactive power which may be sourced or consumed by an input filter circuit. In one aspect, the power conversion system can receive externally supplied multi-phase AC electric power, such as three-phase power from a power grid, and use a converter circuit to generate a DC bus. The power conversion system can then use an inverter circuit to generate multi-phase AC electric power from the DC bus for driving the load with adjustable frequencies and/or amplitudes as desired. The input filter circuit can be coupled to the converter circuit to filter out harmonics resulting from switching of the converter circuit. The power conversion system can receive feedback signals which may be used to determine reactive power sourced or consumed by the filter circuit, and can adjust the converter circuit to compensate for such reactive power.

Abstract: A power conversion system can be implemented to reduce load disturbances on a DC bus which may be caused by load activity, such as a motor starting, stopping and/or ramping up or down. In one aspect, the power conversion system can receive externally supplied multi-phase AC electric power, such as three-phase power from a power grid, and use a converter circuit to generate the DC bus. The power conversion system can then use an inverter circuit to generate multi-phase AC electric power from the DC bus for driving the load with adjustable frequencies and/or amplitudes as desired. The power conversion system can receive feedback signals to sense the load activity and adjust the converter and/or inverter circuits accordingly to reduce the load disturbances on the DC bus.

Abstract: Power conversion systems and methods are provided for ride through of abnormal grid conditions or disturbances, in which a system rectifier is operated in a first mode to regulate a DC voltage of an intermediate DC circuit, an inverter is operated in the first mode to convert DC power from the intermediate DC circuit to provide AC output power to drive a load. In response to detecting an abnormal grid condition, the system changes to a second mode in which the rectifier is turned off and the inverter regulates the DC voltage of the intermediate DC circuit using power from the load.

Abstract: Power conversion systems and methods are provided for ride through of abnormal grid conditions or disturbances, in which a system rectifier is operated in a first mode to regulate a DC voltage of an intermediate DC circuit, an inverter is operated in the first mode to convert DC power from the intermediate DC circuit to provide AC output power to drive a load. In response to detecting an abnormal grid condition, the system changes to a second mode in which the rectifier is turned off and the inverter regulates the DC voltage of the intermediate DC circuit using power from the load.

Abstract: Impedance detection methods and systems are presented for automatic computation of an electrical component impedance value at one or more specific frequencies of interest using quadrature voltage and current values generated by quadrature tracking filters based on sensed or measured voltage and current signals or values and a base frequency input.

Abstract: Described herein are methods, systems, and apparatuses for determining sag in a signal. In one example, a method of tracking sag in a signal includes, when in an initial state, monitoring for when the signal transitions to a sag state based at least on an output of a tracking filter. In response to the signal transitioning to the sag state, increasing a bandwidth of the tracking filter and, when in the sag state, monitoring for when the signal transitions to a recovering state. The method further includes, in response to the signal transitioning to the recovering state, decreasing the bandwidth of the tracking filter.

Abstract: Present embodiments relate to a method for synchronizing an electric grid. The method includes receiving a phase voltage of the electric grid. The method further includes determining one or more disturbance frequencies in the phase voltage via a plurality of sequential tracking filters, wherein each of the plurality of tracking filters corresponds to a harmonic of the received phase voltage. The method further includes removing the disturbance frequencies components sequentially to produce a minimally distorted frequency, and performing a PLL operation on the clean frequency to determine a phase angle of the frequency.

Abstract: Present embodiments relate to a method for synchronizing an electric grid. The method includes receiving a phase voltage of the electric grid. The method further includes determining one or more disturbance frequencies in the phase voltage via a plurality of sequential tracking filters, wherein each of the plurality of tracking filters corresponds to a harmonic of the received phase voltage. The method further includes removing the disturbance frequencies components sequentially to produce a minimally distorted frequency, and performing a PLL operation on the clean frequency to determine a phase angle of the frequency.

Abstract: A phase angle detector with a PLL, a power converter, and a method for reducing offsets in an input signal, in which an adaptive offset processor selectively removes a DC offset component from the input signal to generate a modified signal including a fundamental frequency component and higher order harmonics of the input signal with the DC offset component removed, and the PLL provides a phase angle signal at least partially according to the modified signal.

Abstract: Impedance detection methods and systems are presented for automatic computation of an electrical component impedance value at one or more specific frequencies of interest using quadrature voltage and current values generated by quadrature tracking filters based on sensed or measured voltage and current signals or values and a base frequency input.

Abstract: Described herein are methods, systems, and apparatuses for determining sag in a signal. In one example, a method of tracking sag in a signal includes, when in an initial state, monitoring for when the signal transitions to a sag state based at least on an output of a tracking filter. In response to the signal transitioning to the sag state, increasing a bandwidth of the tracking filter and, when in the sag state, monitoring for when the signal transitions to a recovering state. The method further includes, in response to the signal transitioning to the recovering state, decreasing the bandwidth of the tracking filter.