# US 10,500,965 B2 · Dithering a pulse width modulated base frequency to reduce EV noise > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,500,965 B2 - Document ID: US10500965B2 - Status: Granted - Kind: B2 - Application number: 15/366,023 - Filed: 2016-12-01 - Published: 2018-06-07 - Granted: 2019-12-10 - Earliest claimed: 2016-12-01 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Jiyao Wang; Wei Xu - Web page: https://patentgrep.com/patent/US10500965B2 ## CPC - B60L 53/14: Conductive energy transfer - B60L 50/51: characterised by AC-motors - B60L 53/24: Using the vehicle's propulsion converter for charging - H02P 6/28: Arrangements for controlling current (H02P6/10 takes precedence) - H02P 27/08: with pulse width modulation - B60L 2210/10: DC to DC converters - Y02T 10/64: Electric machine technologies in electromobility - Y02T 10/70: Energy storage systems for electromobility, e.g. batteries - Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors - Y02T 10/72: Electric energy management in electromobility - Y02T 90/12: Electric charging stations - Y02T 90/14: Plug-in electric vehicles - Y10S 903/906: Motor or generator - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## 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. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) The vehicle powertrain of claim 1, wherein the PWM signal is a Space Vector PWM (SVPWM) signal selected to increase the distribution of the energy at sidebands of a second harmonic of the base frequency. ### Claim 3 (depends on 1) The vehicle powertrain of claim 1, wherein the PWM signal is a Discontinues PWM (DPWM) signal selected to spread energy to sidebands of both the base frequency and a second harmonic of the base frequency. ### Claim 4 (depends on 1) The vehicle powertrain of claim 1, wherein the controller is further configured to toggle the PWM signal between a Space Vector PWM (SVPWM) signal and a Discontinues PWM (DPWM) signal. ### Claim 5 (depends on 4) The vehicle powertrain of claim 4, wherein the controller is further configured to toggle the base frequency based on a percentage to optimize energy spread between the base frequency and a second harmonic of the base frequency. ### Claim 6 (depends on 5) The vehicle powertrain of claim 5, wherein the percentage is based on a base frequency sideband exceeding a second harmonic sideband of the base frequency. ### Claim 7 (depends on 1) The vehicle powertrain of claim 1, wherein the controller is further configured to dither the PWM signal pseudorandomly. ### Claim 8 (depends on 1) The vehicle powertrain of claim 1, 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. ### Claim 9 (depends on 1) The vehicle powertrain of claim 1, wherein the controller is further configured to dither the base frequency based on the rotational speed of the electric machine and the base frequency such that energy at the sidebands does not overlap. ### Claim 10 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. ### Claim 11 (depends on 10) The vehicle of claim 10, wherein the PWM signal is a Space Vector PWM (SVPWM) signal selected to increase a distribution of the energy at sidebands of a second harmonic of the base frequency. ### Claim 12 (depends on 10) The vehicle of claim 10, wherein the PWM signal is a Discontinues PWM (DPWM) signal selected to spread energy to sidebands of both the base frequency and a second harmonic of the base frequency. ### Claim 13 (depends on 10) The vehicle of claim 10, wherein the controller is further configured to toggle the PWM signal between a Space Vector PWM (SVPWM) signal and a Discontinues PWM (DPWM) signal. ### Claim 14 (depends on 13) The vehicle of claim 13, wherein the controller is further configured to toggle the base frequency based on a percentage to optimize energy spread between the base frequency and a second harmonic of the base frequency. ### Claim 15 (depends on 14) The vehicle of claim 14, wherein the percentage is based on a base frequency sideband exceeding a second harmonic sideband of the base frequency. ### Claim 16 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. ### Claim 17 (depends on 16) The method of claim 16, wherein the dithering includes pseudorandomly dithering the PWM signal.