Abstract: A power conversion circuit having a solid-state circuit breaker integrated therein is disclosed. With a disconnect switch between a utility source and the power conversion apparatus described for meeting UL489, the power conversion circuit includes an input connectable to an AC source, a rectifier circuit connected to the input to convert an AC power input to a DC power, and a DC link coupled to the rectifier circuit to receive the DC power therefrom. The rectifier circuit comprises a plurality of phase legs each including thereon an upper switching unit and a lower switching unit, wherein at least one of the upper and lower switching units on each phase leg comprises a bi-directional switching unit that selectively controls current and withstands voltage in both directions, so as to provide a circuit breaking capability that selectively interrupts current flow through the rectifier circuit, while maintaining original power conversion functionalities.

Abstract: A control system for controlling operation of main and secondary drive units in a web winder system to provide tension control of a continuous material web is disclosed. The control system causes the main drive unit to operate in a velocity mode to set a linear velocity of the continuous material web. The control system receives inputs from tension and speed detectors in the web winder system that detect a tension and speed of the continuous material web and causes the secondary drive unit to operate in a modified torque regulated closed-loop tension control mode so as to control a tension in the web material, with the control system causing the secondary drive unit to operate according to a torque regulated closed-loop tension control mode and integrate a speed feedback loop into the torque regulated closed-loop tension control mode so as to introduce active damping into the tension control.

Abstract: An adjustable speed drive (ASD) circuit includes a rectifier bridge to convert an AC power input to a DC power, a DC link coupled to the rectifier bridge to receive the DC power, a DC link capacitor bank comprising at least first and second capacitors connected to the DC link, each capacitor having a capacitor voltage thereacross, and a protection circuit including a detection circuit configured to detect a short circuit on one or more of the first and second capacitors of the DC link capacitor bank and generate an action signal upon detection of a short circuit on one or more of the first and second capacitors of the DC link capacitor bank. The ASD circuit also includes an action circuit in operable communication with the detection circuit and configured to cause a short circuit across the DC link upon receiving the action signal from the detection circuit.

Abstract: An adjustable speed drive (ASD) circuit includes a rectifier bridge to convert an AC power input to a DC power, a DC link coupled to the rectifier bridge to receive the DC power, a DC link capacitor bank comprising at least first and second capacitors connected to the DC link, each capacitor having a capacitor voltage thereacross, and a protection circuit including a detection circuit configured to detect a short circuit on one or more of the first and second capacitors of the DC link capacitor bank and generate an action signal upon detection of a short circuit on one or more of the first and second capacitors of the DC link capacitor bank. The ASD circuit also includes an action circuit in operable communication with the detection circuit and configured to cause a short circuit across the DC link upon receiving the action signal from the detection circuit.

Abstract: A system and method for speed regulation of a VFD circuit via an anti-windup control scheme that provides consistent speed response with no overshoot is disclosed. A control system for operating the VFD circuit includes a feedback controller programmed to receive a speed of a motor operating responsive to an initial torque command and process the speed of the motor to generate a feedback controller output. A feedforward controller of the control system is programmed to process a speed reference to generate a feedforward controller output. A command module of the control system is programmed to determine a torque command based on the processed outputs of the feedback and feedforward controllers and operate the VFD circuit to control the motor according to the torque command.

Abstract: A power converter for operating a three-phase AC electrical machine from a single phase AC power source includes an ASD having a rectifier and inverter, and an add-on power conversion module external to the ASD that is electrically connected to each of the power source and the ASD. The power conversion module includes one or more input inductors configured to store and filter single-phase AC power received from the power source and a pair of switching devices connected to each of the input inductors at an output end thereof. A controller operably connected to the power conversion module selectively controls switching of the pair of switching devices associated with each of the one or more input inductors so as to cause a sinusoidal single phase AC power to be output from the add-on power conversion module for rectification by the rectifier.

Abstract: An ASD circuit includes an input, solid-state switch rectifier bridge, DC link, and DC link capacitor bank. A pre-charge circuit is coupled between the input and the DC link capacitor bank and includes pre-charge relays operable in an on state that allows the AC power input to power the rectifier bridge during a normal operating state and an off state that allows the AC power input to pre-charge the DC link capacitor bank through a pre-charge resistor of the pre-charge circuit during a pre-charge operating state. A protection relay of a protection circuit is coupled between the pre-charge relays and the DC link capacitor bank, the protection relay operable in an on state that prevents the pre-charge circuit from connecting to the DC link capacitor bank when a capacitor short circuit occurs and an off state that allows the pre-charge circuit to electrically connect to the DC link capacitor bank.

Abstract: A power converter for operating a three-phase AC electrical machine from a single phase AC power source includes an ASD having a rectifier and inverter, and an add-on power conversion module external to the ASD that is electrically connected to each of the power source and the ASD. The power conversion module includes one or more input inductors configured to store and filter single-phase AC power received from the power source and a pair of switching devices connected to each of the input inductors at an output end thereof. A controller operably connected to the power conversion module selectively controls switching of the pair of switching devices associated with each of the one or more input inductors so as to cause a sinusoidal single phase AC power to be output from the add-on power conversion module for rectification by the rectifier.

Abstract: A disturbance, for example, a frequency variation, is generated in at least a portion of the power distribution network. The disturbance may be generated, for example, by an uninterruptible power supply (UPS) or some other component of the power distribution network, such as a switch. At least one node of the network experiencing the disturbance is identified and a topology of the power distribution network is determined responsive to identifying the at least one node. The at least one node may be identified by detecting a voltage-related artifact corresponding to the disturbance. A phase-locked loop (PLL)—based circuit may be used for fast artifact detection. Groups of devices in the network may be identified from the artifacts, and combinatorial optimization techniques may be used to determine connectivity within such groups.

Abstract: A system and method for capturing current information for a power converter is disclosed. The current monitoring system includes a control system operably connected to a circuit having a plurality of semiconductor switches that are controllable to convert an input power to an output power having a desired voltage and current. The control system includes a PWM signal generator to generate switching signals that control switching of the switches, gate drivers to facilitate switching of the switches, and desaturation circuits to provide overcurrent protection to the switches. The control system further includes a processor that receives voltage data from the desaturation circuits regarding a measured voltage across each of the switches, determines a current through each of the switches based on the voltage across each respective switch, and calculates an input current to the circuit or an output current of the circuit based on the determined currents through the switches.

Abstract: A ventilation system includes first and second blowers connected to a plenum in parallel, with a first motor drive to control a speed of an electric motor of the first blower and a second motor drive to control a speed of an electric motor of the second blower. A controller associated with the first blower is programmed to receive a set point for a controlled variable that is controllable by operation of the first and second blowers, estimate a total air flow required from the first and second blowers to reach the controlled variable set point, calculate a blower speed ratio between a first blower speed and a second blower speed that provides the required total air flow at a minimum power consumption level, and generate commands to cause the first blower and the second blower to operate at speeds resulting in the calculated blower speed ratio.

Abstract: A system and method for determining a rotor time constant of an AC induction machine is disclosed. During operation of the induction motor, a flux signal is injected into a rotor flux command so as to generate a time-variant rotor flux. A voltage-current flux observer determines amplitudes of rotor flux variations resulting from the time-variant rotor flux, with the amplitudes of the rotor flux variations comprising an amplitude of a rotor flux variation based on a current model of the voltage-current flux observer and an amplitude of a rotor flux variation based on a combined voltage-current model of the voltage-current flux observer. A rotor time constant of the induction motor is then estimated based on the determined amplitudes of the rotor flux variations.

Abstract: A system and method for controlling an adjustable speed drive (ASD) to decelerate an AC load during a generating mode of operation is disclosed. The ASD includes a capacitor and an inverter coupled to a DC link. A current sensor system is coupled to an output of the inverter. The ASD further includes a control system programmed to calculate an energy of the capacitor, generate a reference power using the calculated capacitor energy, and calculate a feedback power from realtime current signals received from the current sensor system. The control system compares the feedback power to the reference power, defines a frequency offset based on the comparison, generates a speed command using the frequency offset, and outputs the speed command to the inverter to maintain a smooth DC link voltage during deceleration.

Abstract: A variable frequency drive (VFD) circuit includes an input connectable to an AC source, a rectifier to convert an AC power input to a DC power, a DC link to receive DC power from the rectifier and having a DC link voltage thereon, a DC link capacitor bank with one or more capacitors connected to the DC link, and a pre-charge circuit coupled to the DC link capacitor. The pre-charge circuit further includes one or more resistors, one or more pre-charge relays each operable in on and off states to selectively control a current flow through the resistor(s) so as to control an initial pre-charge of the DC link capacitor, and an overvoltage relay operable in on and off states to selectively cut-off a current flow to the DC link capacitor bank, so as to prevent an overvoltage condition in the DC link capacitor bank.

Abstract: A three-phase resonant cyclo-converter, the cyclo-converter comprising a feed forward control module arranged to develop a feed forward signal for controlling a switching frequency of the cyclo-converter dependent on conditions of a power supply arranged to provide power to the cyclo-converter.

Abstract: A system for optimizing switching dead-time includes a power converter that includes a half-bridge circuit comprising a first switch coupled in series with a second switch, first and second state detection circuits respectively coupled to the first and second switches and configured to respectively detect an activation state of the first and second switches. First and second switch control circuits coupled respectively to the first and second switches are configured to respectively toggle the first and second switches between an activate state and a deactivated state. The first switch control circuit includes a first input configured to receive an activation signal from the second state detection circuit indicative of the activation state of the second switch, and the second switch control circuit includes a first input configured to receive an activation signal from the first state detection circuit indicative of the activation state of the first switch.

Abstract: A system and method for detecting ground faults in an AC motor drive is disclosed. A fault detection and protection system for an AC motor drive includes current sensors to measure first and second phase output currents, a voltage sensor to measure a DC link voltage, and a desaturation control circuit to determine a voltage and associated current across PWM inverter switches for a third phase of the output. A controller compares the first and second phase currents, the measured DC link voltage, and the voltage across the PWM inverter switches on the third phase, to a plurality of thresholds. The controller detects a ground fault on one of the first, second, and third phases of the three phase output to the AC motor based on the comparisons of the first and the second phase currents, the DC link voltage, and the voltage across the switches to the thresholds.

Abstract: A three-phase resonant cyclo-converter comprising a power control module, wherein the power control module is arranged to develop a plurality of repeating switching periods within a cycle, the power control module further arranged to: control the length of a first switching period in the cycle to adjust the power flow, and control the relative length of two or more further switching periods in the cycle to adjust the power factor, wherein the relative length is controlled based on a cross-product of voltage and current values associated with the further switching periods.

Abstract: A system and method for controlling an adjustable speed drive (ASD) to decelerate an AC load during a generating mode of operation is disclosed. The ASD includes a capacitor and an inverter coupled to a DC link. A current sensor system is coupled to an output of the inverter. The ASD further includes a control system programmed to calculate an energy of the capacitor, generate a reference power using the calculated capacitor energy, and calculate a feedback power from realtime current signals received from the current sensor system. The control system compares the feedback power to the reference power, defines a frequency offset based on the comparison, generates a speed command using the frequency offset, and outputs the speed command to the inverter to maintain a smooth DC link voltage during deceleration.

Abstract: A system and method for determining a rotor time constant of an AC induction machine is disclosed. During operation of the induction motor, a flux signal is injected into a rotor flux command so as to generate a time-variant rotor flux. A voltage-current flux observer determines amplitudes of rotor flux variations resulting from the time-variant rotor flux, with the amplitudes of the rotor flux variations comprising an amplitude of a rotor flux variation based on a current model of the voltage-current flux observer and an amplitude of a rotor flux variation based on a combined voltage-current model of the voltage-current flux observer. A rotor time constant of the induction motor is then estimated based on the determined amplitudes of the rotor flux variations.