A damper for a power train, comprising a piezoelectric transformer and a load element connected across the output of the piezoelectric transformer.

A damper for a power train, comprising a piezoelectric transformer and a load element connected across the output of the piezoelectric transformer.

A torsional mode damping controller in which the controller modifies electrical power to an electrical motor to provide active damping control of torsional vibration in rotating masses. The controller receives a measurement of a rotational speed of the rotating masses ω.sub.m and an estimate or a measurement of a torque transmitted between the rotating masses T.sub.sh; based on the received transmitted torque T.sub.sh, generate a compensating torque to suppress vibration T.sub.com; based on the received rotational speed ω.sub.m and the compensating torque T.sub.com, generate an electromagnetic torque modification signal T.sub.modi; and modify the electrical power provided to the electrical motor on the basis of the electromagnetic torque modification signal T.sub.modi. The controller is further configured to generate compensating torque T.sub.com by applying a filter to the received transmitted torque T.sub.sh, based on plural tunable parameters including a tuning gain K, a cut-off frequency ω.sub.n and a resonant damping ratio ζ.

A torsional mode damping controller in which the controller modifies electrical power to an electrical motor to provide active damping control of torsional vibration in rotating masses. The controller receives a measurement of a rotational speed of the rotating masses ω.sub.m and an estimate or a measurement of a torque transmitted between the rotating masses T.sub.sh; based on the received transmitted torque T.sub.sh, generate a compensating torque to suppress vibration T.sub.com; based on the received rotational speed ω.sub.m and the compensating torque T.sub.com, generate an electromagnetic torque modification signal T.sub.modi; and modify the electrical power provided to the electrical motor on the basis of the electromagnetic torque modification signal T.sub.modi. The controller is further configured to generate compensating torque T.sub.com by applying a filter to the received transmitted torque T.sub.sh, based on plural tunable parameters including a tuning gain K, a cut-off frequency ω.sub.n and a resonant damping ratio ζ.

A motor drive that outputs a sinusoidal waveform utilizes power switching devices operable at high switching frequencies. The switching devices may be operated, for example, between twenty kilohertz and one megahertz. A first filter is included at the output of the motor drive which has a bandwidth selected to attenuate voltage components at the output which are at the switching frequency or multiples thereof such that the output voltage waveform is generally sinusoidal. Additional filtering is included within the motor drive to establish a circulation path for common mode currents within the motor drive. Further, a shield is provided adjacent to those components within the motor drive that may experience voltage or current waveforms at the switching frequency or multiples thereof to cause radiated emissions to establish eddy currents within the EMI shield rather than passing through the shield into the environment.

A motor drive that outputs a sinusoidal waveform utilizes power switching devices operable at high switching frequencies. The switching devices may be operated, for example, between twenty kilohertz and one megahertz. A first filter is included at the output of the motor drive which has a bandwidth selected to attenuate voltage components at the output which are at the switching frequency or multiples thereof such that the output voltage waveform is generally sinusoidal. Additional filtering is included within the motor drive to establish a circulation path for common mode currents within the motor drive. Further, a shield is provided adjacent to those components within the motor drive that may experience voltage or current waveforms at the switching frequency or multiples thereof to cause radiated emissions to establish eddy currents within the EMI shield rather than passing through the shield into the environment.

With an electric compressor including a rotational shaft, a compressor wheel disposed on the rotational shaft, and an electric motor for applying a rotational force to the rotational shaft including a rotor fixed to the rotational shaft, and a stator disposed around the rotor, for applying the rotational force to the rotor by an electromagnetic force, a vibration/noise reduction device includes a detector for detecting a frequency related to a vibration of the stator, and a signal generator for generating a vibration signal that has a frequency of a predetermined integral multiple of an electrical angle frequency, which is obtained from the frequency detected by the detector, and has a signal wave attenuating the vibration of the stator, and a vibrator for vibrating the electric compressor based on the vibration signal.

With an electric compressor including a rotational shaft, a compressor wheel disposed on the rotational shaft, and an electric motor for applying a rotational force to the rotational shaft including a rotor fixed to the rotational shaft, and a stator disposed around the rotor, for applying the rotational force to the rotor by an electromagnetic force, a vibration/noise reduction device includes a detector for detecting a frequency related to a vibration of the stator, and a signal generator for generating a vibration signal that has a frequency of a predetermined integral multiple of an electrical angle frequency, which is obtained from the frequency detected by the detector, and has a signal wave attenuating the vibration of the stator, and a vibrator for vibrating the electric compressor based on the vibration signal.

A variety of methods, controllers and electric machine systems are described that facilitate pulsed control of electric machines to improve the energy efficiency of the electric machine when conditions warrant. Selected transitions between pulsing output levels are controlled to provide a cubic or higher order transition torque profile. In various implementations, cubic, quintic or higher order transition profiles are use. The use of such transition torque profiles can improve NVH characteristics of the electric machine while providing energy efficient pulse transitions.

A variety of methods, controllers and electric machine systems are described that facilitate pulsed control of electric machines to improve the energy efficiency of the electric machine when conditions warrant. Selected transitions between pulsing output levels are controlled to provide a cubic or higher order transition torque profile. In various implementations, cubic, quintic or higher order transition profiles are use. The use of such transition torque profiles can improve NVH characteristics of the electric machine while providing energy efficient pulse transitions.