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US 10,500,965 B2Granted
Dithering a pulse width modulated base frequency to reduce EV noise
AssigneeFord Global Technologies, LLC
InventorsJiyao Wang, Wei Xu
Life of this patent
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Abstract
A vehicle powertrain includes an inverter coupled with an electric machine and a controller. The controller may be configured to dither a base frequency of a pulse width modulated (PWM) signal, by less than an amount that is based on a rotational speed of the machine and the base frequency, to operate the inverter such that energy at sidebands and harmonics of the base frequency are reduced by distributing the energy to reduce audible vibrations of the powertrain.
Claims17
A vehicle powertrain comprising:
- an inverter coupled with an electric machine;
- and
- a controller configured to dither a base frequency of a pulse width modulated (PWM) signal, by less than an amount that is based on a rotational speed of the machine and the base frequency, to operate the inverter such that energy, at sidebands and harmonics of the base frequency, is reduced by distributing the energy to reduce audible vibrations of the powertrain, wherein the controller is further configured to increase the amount to a predetermined amount when the rotational speed of the electric machine is less than a fifth of the base frequency.
A vehicle comprising:
- a powertrain having an inverter coupled with an electric machine;
- and
- a controller configured to randomly alter a base frequency of a pulse width modulated (PWM) signal for the inverter by less than an amount that is based on a rotational speed of the machine and the base frequency such that energy at sidebands and harmonics of the base frequency are reduced to reduce audible vibrations of the powertrain, wherein the amount is at least 2 times the rotational speed of the electric machine when the rotational speed is greater than the base frequency.
A method of controlling a vehicle powertrain electric machine comprising:
- dithering by a controller about a base frequency of a pulse width modulated (PWM) signal within a frequency range that is based on a rotational speed of the electric machine to operate the machine to reduce audible vibrations of the powertrain;
- toggling the PWM signal between a Space Vector PWM (SVPWM) mode and a Discontinues PWM (DPWM) mode based on a percentage of operating time in the SVPWM mode;
- and
- in response to energy at sidebands of a second harmonic of the base frequency exceeding the energy at sidebands of the base frequency, increasing the percentage of operating time in the SVPWM mode.
1 more element
Dependencies are inferred from the claim text.