Limited-pool random frequency for DC brush motor low frequency PWM speed control
AssigneeSiemens VDO Automotive Corporation
InventorSylvain Nadeau
Life of this patent
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Abstract
A motor control system 10 includes an engine cooling module 14 including a DC motor 12. The system includes a switch 18 constructed and arranged to be controlled by a pulse width modulated (PWM) signal 26. The switch 18 is operatively associated with the DC motor to control current to the DC motor and thus control the speed of the DC motor. A controller 20 is operatively associated with the switch. The controller is constructed and arranged to select periods, of a limited-pool of frequencies each being less than 500 Hz, from a pseudo-random sequence of periods and to send the selected periods to the switch, thereby controlling noise and vibration of the module.
Claims18
A method of controlling speed of a DC brush motor using a low frequency pulse width modulated (PWM) signal, the method including:
- providing a limited-pool of frequencies, with each frequency of the limited-pool being less than 500 Hz,
- determining a period of each of the frequencies of the limited-pool,
- creating a pseudo-random sequence of the periods,
- selecting a period from the pseudo-random sequence of periods, and
- using the selected period as the period of the PWM signal to control speed of the DC brush motor,
- wherein at least two different frequencies comprise the limited-pool.
A method of controlling speed of a DC brush motor using a low frequency pulse width modulated (PWM) signal, the method including:
- providing a pseudo-random limited-pool of frequencies, with each frequency of the limited-pool being less than 500 Hz,
- organizing the frequencies of the limited-pool into a pseudo-random sequence frequencies,
- selecting a frequency from the pseudo-random sequence, and
- using the selected frequency as the frequency of the PWM signal to control speed of the DC brush motor,
- wherein at least two different frequencies comprise the limited-pool.
A motor control system comprising:
- an engine cooling module including a DC motor,
- a switch constructed and arranged to be controlled by a pulse width modulated (PWM) signal, the switch being operatively associated with the DC motor to control current to the DC motor and thus control the speed of the DC motor, and
- a controller operatively associated with the switch, the controller being constructed and arranged to select periods, of a limited-pool of at least two different frequencies each being less than 500 Hz, from a pseudo-random sequence of said periods and to send the selected periods to the switch, thereby controlling noise and vibration of the module.
A motor control system comprising:
- an engine cooling module including a DC motor,
- a switch constructed and arranged to be controlled by a pulse width modulated (PWM) signal, the switch being operatively associated with the DC motor to control current to the DC motor and thus control the speed of the DC motor, and
- means for controlling the switch operatively associated with the switch, the means for controlling being constructed and arranged to select periods, of a limited-pool of at least two different frequencies between 300 Hz and 400 Hz, from a pseudo-random sequence of said periods and to send the selected periods to the switch, thereby controlling noise and vibration of the module.
Dependencies are inferred from the claim text.