Synchronous sampling of PWM waveforms
First Claim
1. A device for filtering a carrier frequency of a PWM waveform, the PWM waveform having one or more pulses wherein each pulse is created at the carrier frequency, the device comprising:
- a low-pass filter converting the PWM waveform into an analog signal;
a sampling analog to digital converter receiving the analog signal from the low-pass filter; and
a controller causing the sampling analog to digital converter to sample the PWM waveform synchronously to the carrier frequency, thereby rejecting the carrier frequency;
wherein for each carrier frequency period there is a pulse leading edge, a pulse trailing edge, a pulse top and a pulse bottom, wherein the controller causes the sampling analog to digital converter to sample at the top of the pulse.
3 Assignments
0 Petitions
Accused Products
Abstract
A device for filtering a carrier frequency of a PWM waveform. The device includes a low-pass filter for converting the PWM waveform into an analog signal. The device further includes a sampling analog-to-digital converter receiving the analog signal from the low-pass filter and the device also includes a controller for causing the non-integrating analog to digital converter to sample the PWM waveform at the pulse frequency rate thereby rejecting the carrier frequency. As already stated the PWM waveform includes a pulse which has a leading edge, a top portion, and a trailing edge. In one embodiment, the controller causes the A/D converter to sample during the top of the pulse. Preferably, the controller causes the A/D converter to sample at substantially the center of the pulse.
24 Citations
43 Claims
-
1. A device for filtering a carrier frequency of a PWM waveform, the PWM waveform having one or more pulses wherein each pulse is created at the carrier frequency, the device comprising:
-
a low-pass filter converting the PWM waveform into an analog signal; a sampling analog to digital converter receiving the analog signal from the low-pass filter; and a controller causing the sampling analog to digital converter to sample the PWM waveform synchronously to the carrier frequency, thereby rejecting the carrier frequency; wherein for each carrier frequency period there is a pulse leading edge, a pulse trailing edge, a pulse top and a pulse bottom, wherein the controller causes the sampling analog to digital converter to sample at the top of the pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A device for filtering a carrier frequency of a PWM waveform, the PWM waveform having one or more pulses wherein each pulse is created at the carrier frequency, the device comprising:
-
a low-pass filter converting the PWM waveform into an analog signal; a sampling analog to digital converter receiving the analog signal from the low-pass filter; and a controller causing the sampling analog to digital converter to sample the PWM waveform synchronously to the carrier frequency, thereby rejecting the carrier frequency; wherein for each carrier frequency period there is a pulse leading edge, a pulse trailing edge, a pulse top and a pulse bottom, wherein the controller causes the sampling analog to digital converter to sample at the bottom of the pulse.
-
-
23. A device for filtering a carrier frequency of a PWM waveform, the PWM waveform having one or more pulses wherein each pulse is created at the carrier frequency, the device comprising:
-
a low-pass filter converting the PWM waveform into an analog signal; a sampling analog to digital converter receiving the analog signal from the low-pass filter; and a controller causing the sampling analog to digital converter to sample the PWM waveform synchronously to the carrier frequency, thereby rejecting the carrier frequency; wherein the controller causes the sampling analog to digital converter to sample at a bottom point of the pulse-width modulated waveform pulse.
-
-
24. A device for filtering a carrier frequency of a PWM waveform, the PWM waveform having one or more pulses wherein each pulse is created at the carrier frequency, the device comprising:
-
a low-pass filter converting the PWM waveform into an analog signal; a sampling analog to digital converter receiving the analog signal from the low-pass filter; and a controller causing the sampling analog to digital converter to sample the PWM waveform synchronously to the carrier frequency, thereby rejecting the carrier frequency; wherein the controller causes the non-integrating analog to digital converter to sample at a center point of the pulse-width modulated waveform pulse and at a bottom point of the pulse-width modulated waveform pulse; and wherein the center point and the bottom point are averaged.
-
-
25. A method for sampling a voltage across a load, the method comprising:
-
filtering in a low pass filter the voltage across a load creating an analog signal wherein the voltage across the load is created using a PWM signal having a carrier frequency; and sampling the analog signal synchronously to the carrier frequency; wherein the PWM signal has one or more pulses and wherein the sampling occurs at a top point of the pulse. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
-
-
41. A method for sampling a voltage across a load, the method comprising:
-
filtering in a low pass filter the voltage across a load creating an analog signal wherein the voltage across the load is created using a PWM signal having a carrier frequency; and sampling the analog signal synchronously to the carrier frequency; wherein the PWM signal has one or more pulses and wherein the sampling occurs substantially at a center top point of the pulse.
-
-
42. A method for sampling a voltage across a load, the method comprising:
-
filtering in a low pass filter the voltage across a load creating an analog signal wherein the voltage across the load is created using a PWM signal having a carrier frequency; and sampling the analog signal synchronously to the carrier frequency; wherein the pulse width modulated signal has one or more pulses and wherein the sampling occurs substantially at a bottom point after the pulse.
-
-
43. A device for filtering a carrier frequency of a PWM waveform, the PWM waveform having one or more pulses wherein each pulse is created at the carrier frequency, the device comprising:
-
a low-pass filter converting the PWM waveform into an analog signal; a sampling analog to digital converter receiving the analog signal from the low-pass filter; and a controller causing the sampling analog to digital converter to sample the PWM waveform synchronously to the carrier frequency, thereby rejecting the carrier frequency; wherein the PWM waveform has one or more consecutive pulse periods of duration T=1/fc, where fc is the carrier frequency; and wherein the low-pass filter has a transfer function having a dominant pole with a time constant between 0.1T and 5T.
-
Specification