Abstract: A system and method for monitoring the health of a Litz wire. This can be done by representing the wire as a transmission line that is terminated at each end. A pulse can be induced in the transmission line and monitored with and using time domain reflectometry (TDR) to monitor the state of strands of the Litz wire.

Abstract: A compensator circuit for a PWM active rectifier includes a look up table containing compensating voltage values for given values of input phase current and input voltage frequency, and a low pass filter arranged to filter the input phase current to the rectifier based on a filter bandwidth determined according to the input voltage frequency. The compensator circuit arranged to receive measured input current and voltage frequency values and to output corresponding compensation voltage values from the look up table, the compensation voltages to be provided, in use, to the rectifier to adjust the switching pattern of the rectifier.

Abstract: A method for monitoring insulation in a motor drive circuit configured to convert DC power from a power source to AC power to drive a motor. The method includes boosting a DC link voltage of an inverter of the motor drive, isolating the motor drive circuit from the power source; performing at least one isolation test by providing a current path through components of the motor drive and preferably a motor connected to the output of the inverter to be tested; and monitoring the current during each isolation test to detect partial discharge or excessive leakage from the current path, thereby indicating that there exists defects in the insulation in the current path.

Abstract: A multilevel power converter comprising: a DC bus having a positive terminal and a negative terminal; a plurality of switches for each of a plurality of phase legs of the power converter connected between the positive terminal and the negative terminal, each power leg having an output for provided a converted voltage output according to the switching control of the plurality of switches; and one or more current sensors, wherein at least two of the switches, or at least one of the switches and a current sensor, and/or at least two current sensors are connected as a cluster to share a common power supply.

Abstract: A multilevel power converter comprising: a DC bus having a positive terminal and a negative terminal; a plurality of switches for each of a plurality of phase legs of the power converter connected between the positive terminal and the negative terminal, each power leg having an output for provided a converted voltage output according to the switching control of the plurality of switches; and wherein a current sensor provided in each phase leg connected in series between an adjacent pair of the plurality of switches.

Abstract: A controller for a DC-AC inverter circuit. The circuit comprises two terminals for receiving a DC-link voltage, two or more capacitors connected in series between the two terminals, wherein each capacitor has a capacitor voltage. The circuit is configured to convert an input electrical power to an output electrical power for operating a main electrical load. The controller is configured to, in response to the main electrical load becoming non-operational, configure the circuit into a balancing mode. In the balancing mode the controller configures the circuit to output electrical power to an electrical component, such that the DC-AC inverter circuit remains operational to balance the capacitor voltages while the main electrical load remains non-operational.

Abstract: A method for monitoring insulation in a power system comprising a motor drive circuit configured to provide AC power from a power source to power a motor. The method includes: boosting a DC link voltage of an inverter of the motor drive by an active rectifier, the active rectifier converting the AC power from the power source to DC power for the inverter; isolating the motor drive circuit from the power source; performing at least one isolation test by providing a current path through components of the motor drive and optionally a motor connected to the output of the inverter to be tested; monitoring the current during each isolation test to detect partial discharge or excessive leakage from the current path, thereby indicating that there exist one or more defect(s) in the insulation in the current path.

Abstract: A snubber circuit to mitigate voltage overshoot in a power train for driving a motor, the snubber circuit configured to be connected to the motor terminal between a transmission line from a power supply and converter and a motor. The snubber circuit includes a rectifier, a capacitor connected across an output of the rectifier and a load connected across the capacitor. The capacitor is rated to charge to a predetermined link voltage and wherein an input voltage to the rectifier that exceeds the link voltage causes the voltage at the motor terminal to clamp to the link voltage and for excess energy from the input voltage to be stored in the link capacitor and dissipated by the load.

Abstract: An EMI filter arrangement includes a noise source, an input filter connected to the input of the noise source, and an output filter connected to the output of the noise source, the noise source, input filter and output filter provided in an electrically conductive electronics box, and an input filter capacitor electrically connecting the input filter to the electrically conductive electronics box and an output filter capacitor electrically connecting the output filter to the electrically conductive electronics box; the arrangement characterised by further comprising an intermediate reference plane provided in the electrically conductive electronics box, and an intermediate capacitor provided in the electrically conductive electronics box electrically connected between the intermediate reference plane and the electrically conductive electronics box, the input filter capacitor and the output filter capacitor being electrically connected to the box via the intermediate reference plane and the intermediate capaci

Abstract: A series resonant power converter, comprising: a first plurality, m, of resonant power converter modules, each comprising a switching stage, a resonant tank, a transformer, a rectifier stage and an output capacitor, the plurality of resonant power converter modules connected in series across a power supply, the resonant power converter further comprising a common output stage (500) connected across the series-connected plurality of resonant power converter modules, whereby a second plurality, n, of output levels at the common output stage.

Abstract: An active electromagnetic interference filter comprising an adjustable shunt impedance circuit, the adjustable shunt impedance circuit comprising a noise sensing branch that senses input noise and provides a noise voltage representative of the sensed noise, and an operational amplifier stage configured to generate, at an injection branch, an injection current based on the noise voltage.

Abstract: A motor drive system includes an input portion arranged to receive a DC input voltage across first and second conductors. An inverter is connected across the first and second conductors, and is arranged such that, in a normal mode, the inverter receives the DC input voltage and generates an AC drive voltage. A motor is connected to the inverter and is arranged such that, in the normal mode of operation, the motor receives the AC drive voltage. A first normally-open switch is connected along the first conductor between the input portion and the inverter. A damping controller comprising a second normally-closed switch and a damping means is connected in series between the first and second conductors. When the operated in the normal mode, the first switch is closed and the second switch is open. In a damping mode, the first switch is open and the second switch is closed.

Abstract: A method for monitoring insulation in a motor drive circuit configured to convert DC power from a power source to AC power to drive a motor. The method includes boosting a DC link voltage of an inverter of the motor drive, isolating the motor drive circuit from the power source; performing at least one isolation test by providing a current path through components of the motor drive and preferably a motor connected to the output of the inverter to be tested; and monitoring the current during each isolation test to detect partial discharge or excessive leakage from the current path, thereby indicating that there exists defects in the insulation in the current path.

Abstract: An AC-DC power converter includes a bridge circuit that has a first phase leg with first and second power switches connected to each other in series, a second phase leg with third and fourth power switches connected to each other in series. The first phase leg and the second phase leg are connected to the each other via a bridging connection to form the bridge circuit. The converter also includes means for providing power to said bridge circuit, and means for measuring an output voltage of said bridge circuit.

Abstract: A system for providing electric motor control to a plurality of motor loads. The system comprises a plurality of motor controllers that are configurable into different arrangements of motor controllers. The system further comprises a central controller that is operable to individually set a phase and/or frequency of respective PWM carrier signals for the motor controllers, wherein the central controller is configured to set the phase and/or frequency of the PWM carrier signals for the motor controllers within a respective arrangement of motor controllers differently depending on the configuration of the motor controllers within the arrangement.

Abstract: A compensator circuit for a PWM active rectifier includes a look up table containing compensating voltage values for given values of input phase current and input voltage frequency, and a low pass filter arranged to filter the input phase current to the rectifier based on a filter bandwidth determined according to the input voltage frequency. The compensator circuit arranged to receive measured input current and voltage frequency values and to output corresponding compensation voltage values from the look up table, the compensation voltages to be provided, in use, to the rectifier to adjust the switching pattern of the rectifier.

Abstract: An EMI filter arrangement includes a noise source, an input filter connected to the input of the noise source, and an output filter connected to the output of the noise source, the noise source, input filter and output filter provided in an electrically conductive electronics box, and an input filter capacitor electrically connecting the input filter to the electrically conductive electronics box and an output filter capacitor electrically connecting the output filter to the electrically conductive electronics box; the arrangement characterised by further comprising an intermediate reference plane provided in the electrically conductive electronics box, and an intermediate capacitor provided in the electrically conductive electronics box electrically connected between the intermediate reference plane and the electrically conductive electronics box, the input filter capacitor and the output filter capacitor being electrically connected to the box via the intermediate reference plane and the intermediate capaci

Abstract: The present invention relates to a system and method for the monitoring and detection of insulation degradation in electric systems. The system comprises a controller for an electric motor (3), including input circuitry (2a) for connecting the controller to a power supply (1), power conversion circuitry (2b) for providing a power output for the electric motor (3), and sensing circuitry (2c) for monitoring a current inside the controller that is representative of a return leakage current from the electric motor to the motor controller. A condition of the insulation may be determined based on the monitored current.

Abstract: A short circuit detection system and method that identifies a short circuit between turns of a winding of a permanent magnet machine having a three-phase winding in response to detection of imbalances between the three motor phases at an instant in time. The imbalances are identified by monitoring motor terminal voltages and currents.

Abstract: A system for providing electric motor control to a plurality of motor loads. The system comprises a plurality of motor controllers that are configurable into different arrangements of motor controllers. The system further comprises a central controller that is operable to individually set a phase and/or frequency of respective PWM carrier signals for the motor controllers, wherein the central controller is configured to set the phase and/or frequency of the PWM carrier signals for the motor controllers within a respective arrangement of motor controllers differently depending on the configuration of the motor controllers within the arrangement.