Electric power conversion systems – Current conversion – With means to introduce or eliminate frequency components
Reexamination Certificate
2001-09-10
2003-04-22
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
With means to introduce or eliminate frequency components
C307S105000, C700S073000
Reexamination Certificate
active
06552919
ABSTRACT:
CROSS-REFERENCE(S) TO RELATED APPLICATION(S)
1. Field of the Invention
The present application relates to power converters, such as those utilized in modern data communications and data processing systems.
2. Background of the Invention
Most modern data processing and/or communication systems are created and designed using digital logic techniques. Digital logic is based on mathematical manipulation of two different symbols, such as logical zero (“0”) and logical one (“1”). When digital logic design techniques are utilized, system designers employ a number of combinational or other type symbolic digital logic elements (e.g., drawings and associated logic tables of AND gates, OR gates, and/or microprocessors or other computational devices which operate on digital logic) in order to create “paper” or “symbolic” designs of data processing and/or data communication systems.
At some point, the digital logic system designers often attempt to implement their symbolic digital logic designs. One common way in which this is done is to implement the symbolic system via an electrical system which mimics the symbolic digital logic design, wherein digital logic zero (“0”) is mimicked via a DC voltage signal having a relatively low voltage value (e.g., logical zero is mimicked via a DC voltage signal set at 0.2 volts) and digital logic one (“1”) is mimicked via a DC voltage signal having a relatively high voltage value (e.g., logical zero is mimicked via a DC voltage signal set at 1 volt). Electrical systems which are used to mimic symbolic digital logic design are hereinafter referred to as “digital logic electrical systems.”
As noted, digital logic electrical systems typically use DC power at relatively low voltage levels. However, those having ordinary skill in the art will recognize that readily available power is generally AC power of relatively high voltage (e.g., the 120 Volt, 60 Hertz AC power available from the North American power grid). Accordingly, in order for such power to be used with digital logic electrical systems, it is necessary to convert such relatively high-voltage AC power to the desired relatively low-voltage DC power. This is typically accomplished in the related art via what will be referred to herein as “power converters.” (Although power converters are being introduced herein in the context of digital logic electrical systems for sake of illustration, those having ordinary skill in the art will appreciate that, as used herein, the term “power converter” is intended to refer to devices which convert electrical power from one form to another (e.g., devices which convert between AC and DC power (or vice versa), devices which convert between high-voltage DC power and low-voltage DC power (or vice versa), devices which convert between high-voltage AC power and low-voltage AC power (or vice versa), etc.))
When power converters are used to power digital logic electrical systems, it is critically important that the electrical signals produced by the power converters be held relatively constant. For example, in a digital logic electrical system where 0.2 volts is utilized to represent logical zero, and 1 volt is utilized to represent logical one, it can be seen that only a 0.8 volt potential difference exists between the electrical signals representative of logical zero and logical one. Accordingly, it is very important that the electrical signals representative of logical zero and logical one fluctuate as little as possible from their desired values.
Unfortunately, fluctuations in electrical signals—even DC electrical signals—are built into the very nature of electrical signals themselves, so in practice it has turned out to be surprisingly difficult to create stable electrical signals representative of logical zeroes and ones. It has been noted by system designers that one significant source of such fluctuations are DC power sources which are used to power digital logic electrical systems. That is, digital logic electrical systems are generally powered by some DC power source, and it has been long recognized that if the output voltage of a DC power source which powers a digital logic electrical system varies, or ripples, such variance or ripple tends to drag the electrical signals throughout the digital logic electrical system up and down, thereby introducing potential sources of digital logic errors into the system.
One way that the foregoing-noted source of error is often dealt with is to use power converters which begin with an extremely high-voltage DC power source wherein the variation, or ripple, in the DC output is tightly controlled (or regulated). Thereafter, the high voltage of the DC power source is successively divided downward, and such divided-down voltage is ultimately utilized to power a digital logic electrical system. Insofar as the DC voltage driving the electrical system is a divided-down version of the high-voltage DC power source, likewise the fluctuations in the DC voltage driving the electrical system are divided-down versions of the fluctuation of the voltage of the DC power source. Hence, provided that the fluctuation of the high-voltage DC power source has been held relatively constant, the DC power source driving the digital logic electrical system is generally extremely stable, which thereby allows the digital logic electrical system to operate in a substantially error free manner. One such type of power converter is known as a “switched mode power supply.”
With reference to the figures, and with reference now to
FIG. 1A
, shown is a related-art switched mode power supply. Illustrated is that rectifier-filter section
102
receives as input a 120 volt AC power signal (e.g., from a wall socket), and transmits as output a rectified and smoothed version of the 120 volt AC power signal (e.g., a quasi-DC (or “ripply”) version of the 120 volt signal, where the amount of ripple present depends upon the amount of the filtering used). Shown is that electrical “gating” or “chopping” device
104
receives as input the quasi-DC output of rectifier-filter section
102
. Depicted is that chopping device
104
intermittently interrupts the received quasi-DC power signal in order to create a high-frequency time-varying (i.e., alternating current, or “AC”) waveform version of the DC power signal as seen by the input of transformer
106
(e.g., chopping device
104
connecting the quasi-DC voltage to the input of transformer
106
for {fraction (1/16000)} of a second, then disconnecting the quasi-DC voltage from the input of transformer
106
for {fraction (1/16000)} second, then reconnecting the quasi-DC voltage to the input of transformer
106
for {fraction (1/16000)} of a second, etc., such that the input of transformer
106
experiences the output of chopping device
104
as essentially an 8000 Hertz (cycles per second) square wave having amplitude varying between 0 and the DC voltage that results from an AC-rectified signal). Illustrated is that transformer
106
accepts as input the created time-varying, or alternating current (AC), power signal and transmits as output a “stepped down,” voltage version of its higher-frequency AC power input signal (transformer
106
is shown and described as what is known in the art as a “step-down” transformer). Thereafter, illustrated is that rectifier-filter-regulator device
108
converts the higher-frequency AC power electrical output of the step-down transformer into circuit-voltage stable DC power (e.g., DC power at a stable 1 volt potential), such stable DC power being thereafter available to power digital logic electrical systems.
With reference now to
FIG. 1B
, shown is the related-art power converter of
FIG. 1A
, but with the addition of feedback circuitry. Depicted is that output-voltage monitor
112
receives a monitored voltage signal
114
. In the related art, output-voltage monitor
112
generally transmits a “feedback” control signal
116
to rectifier-filter device
102
, where control signal
116
is such that it controls the voltage level of the output of rectifier-filter device
102
such that
Riley Shawn
Seed IP Law Group PLLC
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