Abstract: A tabletop having a first half and a second half that rotate about a central axis between an extended position and a storage position. The table includes a hinge disposed between first and second beams attached to the underside of the tabletop adjacent to the central axis. A first support rod is rotatably attached to the underside of the tabletop and has a proximal end attached to a first leg and a distal end having at least two first fingers projecting therefrom. A second support rod is rotatably attached to the underside of the tabletop and has a proximal end attached to a second leg and a distal end having one or more second fingers projecting therefrom. Upon rotation of the first and second legs between extended and collapsed positions, the at least two first fingers engage and disengage with the one or more second fingers.

Abstract: A method for tracking calcium flux of a eukaryotic cell. The method includes growing the eukaryotic cell in the presences of a ytterbium salt in solution and spectroscopically measuring ytterbium in the eukaryotic cell.

Abstract: An electric motor in which at least one of the rotor and the stator has an asymmetric design is disclosed. The electric motor is divided into a number of segments, where each segment has an equal number of windings and an equal number of poles. The physical construction of each pole within a segment is identical and the number of turns of each winding within a segment is identical. The asymmetry is formed by varying the physical construction of the either the rotor or the stator within one segment from the corresponding construction of the rotor or stator in the other segments. The asymmetries are designed to improve one or more operating characteristics such as sensorless performance, torque ripple, or cogging torque in the motor.

Abstract: Disclosed examples include power conversion systems and methods to operate an inverter to drive a motor load through an intervening output filter, a transformer and a cable, including a current regulator to compute a command value according to a current reference value and a motor current feedback value, a cross-coupled feedforward component to compensate the command value by an estimated cross-coupled voltage value to compute a control output value, a cross-coupled object component to compute the motor current feedback value according to a voltage value using a plant transfer function representing the output filter, the transformer, the cable and the motor load, and a controller to provide the inverter switching control signals to control the inverter according to the control output value.

Abstract: Disclosed examples include power conversion systems, methods and computer readable mediums to operate an inverter to drive a motor load through an output filter, in which a control output value is computed according to a current reference value and a current feedback value using a proportional-integral (PI) current regulator, the control output value is filtered using a lag compensator filter to compute an inverter output command value, and the inverter is controlled according to the inverter output command value.

Abstract: An electric motor in which at least one of the rotor and the stator has, an asymmetric design is disclosed. The electric motor is divided into a number of segments, where each segment has an equal number of windings and an equal number of poles. The physical construction of each pole within a segment is identical and the number of turns of each winding within a segment is identical. The asymmetry is formed by varying the physical construction of the either the rotor or the stator within one segment from the corresponding construction of the rotor or stator in the other segments. The asymmetries are designed to improve one or more operating characteristics such as sensorless performance, torque ripple, or cogging torque in the motor.

Abstract: Disclosed examples include motor drive power conversion systems with an inverter, as well as a controller methods to drive a motor in which output filter capacitor currents are computed and used to compensate the motor control in consideration of damping resistance values of an output filter.

Abstract: Disclosed examples include power conversion systems, methods and computer readable mediums to operate an inverter to drive a motor load through an output filter, in which a control output value is computed according to a current reference value and a current feedback value using a proportional-integral (PI) current regulator, the control output value is filtered using a lag compensator filter to compute an inverter output command value, and the inverter is controlled according to the inverter output command value.

Abstract: Disclosed examples include power conversion systems, methods and computer readable mediums to operate an inverter to drive a motor load through an intervening filter, by computing a speed error value according to a speed reference value and a speed feedback value, computing a torque reference value according to the speed error value, computing a motor current reference value according to the torque reference value, compensating the motor current reference value according to capacitor currents of the output filter using a transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load, and controlling the inverter according to the inverter output current reference value.

Abstract: Disclosed examples include motor drive power conversion systems with an inverter, as well as a controller methods to drive a motor in which output filter capacitor currents are computed and used to compensate the motor control in consideration of damping resistance values of an output filter.

Abstract: Motor drives, methods and estimation systems are presented for estimating a rotor position of a motor load in which four sets of inverter output current samples obtained at four different sample times in a given inverter PWM cycle are converted into a corresponding stationary reference frame current value pairs, and the rotor position estimate is computed according to the stationary reference frame current values.

Abstract: Disclosed examples include power conversion systems, methods and computer readable mediums to operate an inverter to drive a motor load through an intervening filter, by computing a speed error value according to a speed reference value and a speed feedback value, computing a torque reference value according to the speed error value, computing a motor current reference value according to the torque reference value, compensating the motor current reference value according to capacitor currents of the output filter using a transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load, and controlling the inverter according to the inverter output current reference value.

Abstract: Motor drive control apparatus and methods are presented for speed reversal control for drives used with output filters and transformers using a high or maximal drive current command to facilitate dissipation of regenerative energy seen in this system during speed reversal with open loop control to reverse the spin direction of a driven motor while quickly transitioning through zero speed.

Abstract: Disclosed examples include power conversion systems and methods to operate an inverter to drive a motor load through an intervening output filter, a transformer and a cable, including a current regulator to compute a command value according to a current reference value and a motor current feedback value, a cross-coupled feedforward component to compensate the command value by an estimated cross-coupled voltage value to compute a control output value, a cross-coupled object component to compute the motor current feedback value according to a voltage value using a plant transfer function representing the output filter, the transformer, the cable and the motor load, and a controller to provide the inverter switching control signals to control the inverter according to the control output value.

Abstract: Cascade H-Bridge inverters and carrier-based level shift pulse width modulation techniques are presented for generating inverter stage switching control signals, in which carrier waveform levels are selectively shifted to control THD and to mitigate power distribution imbalances within multilevel inverter elements using either complementary carrier or complementary reference modulation techniques.

Abstract: Methods and systems are presented for closed loop motor speed and torque control without a sensor at the motor, in which configuration parameters are received from a user interface to define operating characteristics of a filter, a transformer, a cable, and the motor coupled with the output of a motor drive, and an object model of the motor drive is configured according to the filter, transformer, cable and motor configuration parameters to facilitate sensorless closed loop motor speed and/or torque control.

Abstract: Disclosed examples include methods, computer readable mediums and motor drive power conversion systems for sensorless speed control of a motor driven by an inverter through an intervening filter, a transformer and a motor cable, in which sensorless vector control is used to regulate the motor speed based on a speed feedback value computed according to voltage or current values associated with the motor drive using an observer having formulas and impedance parameters of the filter, the transformer, the motor cable and the motor.

Abstract: Motor drives, methods and estimation systems are presented for estimating a rotor position of a motor load in which four sets of inverter output current samples obtained at four different sample times in a given inverter PWM cycle are converted into a corresponding stationary reference frame current value pairs, and the rotor position estimate is computed according to the stationary reference frame current values.

Abstract: Motor drive control apparatus and methods are presented for speed reversal control for drives used with output filters and transformers using a high or maximal drive current command to facilitate dissipation of regenerative energy seen in this system during speed reversal with open loop control to reverse the spin direction of a driven motor while quickly transitioning through zero speed.

Abstract: Motor drive control apparatus and methods are presented for sensorless control of a driven motor using open loop current regulated control during low-speed operation and an EMF-based position observer for position estimation during higher speed operation, with zero feedback speed during low-speed open-loop operation and feedback speed estimated by the EMF-based observer during high-speed operation and with velocity mode control over the full speed range and mode control hysteresis for smooth transitions between open loop and EMF-based observer control.