1. A fuel cell assembly, comprising:
a fuel cell;
a heat exchanger associated with the fuel cell;
an oxidant source;
an oxidant manifold including a manifold inlet operably connected to the oxidant source, a fuel cell path associated with the manifold inlet and the fuel cell, and a heat exchanger path associated with the manifold inlet and the heat exchanger;
a first damper associated with the oxidant manifold fuel cell path; and
a second damper associated with the oxidant manifold heat exchanger path;
wherein the first and second dampers are positioned relative to the oxidant manifold such that at least some of the oxidant from the oxidant source will pass one of the first and second dampers on its way to the other of the first and second dampers.
2. A fuel cell assembly as claimed in claim 1, wherein the fuel cell comprises a PEM fuel cell.
3. A fuel cell assembly as claimed in claim 1, wherein the heat exchanger comprises a plurality of wires.
4. A fuel cell assembly as claimed in claim 1, wherein the oxidant source comprises a single vent and fan arrangement.
5. A fuel cell assembly as claimed in claim 1, wherein the second damper is located upstream from the first damper.
6. A fuel cell assembly as claimed in claim 1, wherein at least one of the first and second dampers comprises an iris damper.
7. A fuel cell assembly as claimed in claim 1, wherein the first and second dampers are independently operable.
8. A fuel cell as assembly as claimed in claim 1, further comprising:
a fuel cell housing in which the fuel cell is supported, the fuel cell housing including a fuel cell housing manifold with a fuel cell path operably connected to the oxidant manifold fuel cell path and a heat exchanger path operably connected to the oxidant manifold heat exchanger path.
9. A fuel cell assembly, comprising:
a fuel cell;
a heat exchanger associated with the fuel cell;
an oxidant source;
an oxidant manifold including a manifold inlet operably connected to the oxidant source, a fuel cell path associated with the manifold inlet and the fuel cell, and a heat exchanger path associated with the manifold inlet and the heat exchanger, the oxidant manifold fuel cell path and heat exchanger path being substantially concentric;
a first damper associated with the oxidant manifold fuel cell path; and
a second damper associated with the oxidant manifold heat exchanger path.
10. A fuel cell assembly as claimed in claim 9, wherein the second damper is located upstream from the first damper.
11. A fuel cell assembly as claimed in claim 10, wherein at least one of the first and second dampers comprises an iris damper.
12. A fuel cell assembly as claimed in claim 9, wherein the first and second dampers are independently operable.
13. A fuel cell assembly as claimed in claim 9, wherein one of the fuel cell path and the heat exchanger path defines a perimeter that extends completely around the other of the fuel cell path and the heat exchanger path.
14. A fuel cell assembly as claimed in claim 9, wherein the heat exchanger path defines a perimeter that extends completely around the fuel cell path.
15. A fuel cell assembly, comprising:
a fuel cell;
a heat exchanger associated with the fuel cell;
an oxidant source;
an oxidant manifold including a manifold inlet operably connected to the oxidant source, a fuel cell path associated with the manifold inlet and the fuel cell, and a heat exchanger path associated with the manifold inlet and the heat exchanger;
a first damper associated with the oxidant manifold fuel cell path;
a second damper associated with the oxidant manifold heat exchanger path; and
a controller, operably connected to the first and second dampers, that selectively adjusts the first and second dampers between respective fully open orientations, partially open orientations, fully closed orientations, and adjusts the first and second dampers to the same orientation in response to a first operating condition and adjusts the first and second dampers to different orientations in response to a second operating condition that is different than the first operating condition.
16. A fuel cell assembly as claimed in claim 15, wherein the second operating condition comprises a relatively cool and wet ambient operating condition and the controller adjusts the first damper to the fully open orientation and the second damper to the fully closed orientation in response to the relatively cool and wet ambient operating condition.
17. A fuel cell assembly as claimed in claim 15, wherein the second operating condition comprises a relatively hot and dry ambient operating condition and the controller adjusts the first damper to the fully closed orientation and the second damper to the fully open orientation in response to the relatively hot and dry ambient operating condition.
18. A fuel cell assembly as claimed in claim 15, wherein the first operating condition comprises an ambient operating condition or a fuel cell operating condition.
19. A fuel cell assembly as claimed in claim 15, wherein the second operating condition comprises an ambient operating condition or a fuel cell operating condition.
20. A fuel cell assembly, comprising:
a fuel cell including and anode and a cathode;
a heat exchanger associated with the fuel cell positioned adjacent to the anode;
an oxidant source that supplies an oxidant flow;
an oxidant manifold including a manifold inlet operably connected to the oxidant source such that the oxidant flow from the oxidant source enters the oxidant manifold, a fuel cell path associated with the manifold inlet and the fuel cell, and a heat exchanger path associated with the manifold inlet and the heat exchanger; and
control means for individually controlling the amount of oxidant flow from the oxidant source to the fuel cell path and the amount of oxidant flow from the oxidant source to the heat exchanger path.
21. A fuel cell assembly as claimed in claim 20, wherein the fuel cell comprises a PEM fuel cell.
22. A fuel cell assembly as claimed in claim 20, wherein the heat exchanger comprises a plurality of wires.
23. A fuel cell assembly as claimed in claim 20, wherein the oxidant source comprises a single vent and fan arrangement.
24. A fuel cell assembly as claimed in claim 20, wherein the oxidant manifold fuel cell path and heat exchanger path are substantially concentric.
25. A fuel cell assembly as claimed in claim 20, further comprising:
a sensor arrangement adapted to measure fuel cell and ambient air temperature, pressure and humidity;
wherein the control means individually controls the amount of oxidant flow from the oxidant source to the fuel cell path and the amount of oxidant flow from the oxidant source to the heat exchanger path based on at last one of fuel cell temperature and humidity and ambient air temperature, pressure and humidity.
26. A fuel cell assembly, comprising:
a fuel cell;
a heat exchanger associated with the fuel cell;
an oxidant source that supplies an oxidant flow;
an oxidant manifold including a fuel cell path associated with the oxidant source and the fuel cell and a heat exchanger path associated with the oxidant source and the heat exchanger; and
means for reducing the amount of oxidant that flows from the oxidant source to the fuel cell path while allowing maximum air flow to the heat exchanger path in response to a first ambient operating condition measurement and reducing the amount of oxidant that flows from the oxidant source to the heat exchanger path while allowing maximum air flow to the fuel cell oath in response to a second ambient operating condition measurement that is different than the first ambient operating condition measurement.
27. A fuel cell assembly as claimed in claim 26, wherein the at least one ambient operating condition comprises ambient temperature.
28. A fuel cell assembly as claimed in claim 27, wherein the at least one ambient operating condition comprises ambient temperature, pressure and humidity.
29. A fuel cell assembly as claimed in claim 26, wherein the at least one ambient operating condition comprises ambient humidity.
30. A fuel cell assembly as claimed in claim 26, wherein the fuel cell comprises a PEM fuel cell.
31. A fuel cell assembly as claimed in claim 26, wherein the heat exchanger comprises a plurality of wires.
32. A fuel cell assembly as claimed in claim 26, wherein the oxidant source comprises a single vent and fan arrangement.
33. A fuel cell assembly as claimed in claim 26, wherein the fuel cell path and heat exchanger path are substantially concentric.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device, comprising:
a first amplifier adapted to generate an analog output signal in response to a digital input signal; and
a power supply adapted to power the first amplifier using a first power rail, wherein the first power rail tracks said output signal and substantially represents a biased and half-wave rectified version of said output signal.
2. The invention of claim 1, wherein the power supply comprises a first power-supply path adapted to generate the first power rail based on the digital input signal.
3. The invention of claim 2, further comprising a main amplification path having the first amplifier, said main amplification path being adapted to process the input signal to generate an M-bit signal, wherein the first power-supply path is adapted to process a K-bit signal carrying K most significant bits (MSBs) of said M-bit signal, where K<M, and generate the first power rail based on said K-bit signal.
4. The invention of claim 3, wherein the main amplification path comprises:
an interpolator and up-sampler (IPUS) adapted to process the input signal to generate said M-bit signal; and
a digital-to-analog converter (DAC) adapted to convert said M-bit signal into a corresponding analog signal, wherein the first amplifier is adapted to amplify said analog signal to generate the analog output signal.
5. The invention of claim 2, wherein the first power-supply path comprises:
a pulse-width modulator (PWM) adapted to process a digital signal corresponding to the input signal to generate a sequence of pulses;
a switching circuit coupled to the PWM and adapted to amplify said sequence of pulses; and
a filter circuit coupled to the switching circuit and adapted to process the amplified sequence of pulses to generate the first power rail.
6. The invention of claim 5, wherein the PWM comprises a digital counter configured to control the widths of pulses in said sequence based on: (i) said digital signal corresponding to the input signal and (ii) a digital control signal controlling an offset voltage between the first power rail and the analog output signal.
7. The invention of claim 6, wherein the digital counter is adapted to perform signal rectification by controlling a range of available duty cycle values for said sequence of pulses.
8. The invention of claim 5, wherein the PWM is a digital PWM adapted to generate a clocked digital signal serving as the sequence of pulses.
9. The invention of claim 2, wherein the first power-supply path further comprises a delay circuit adapted to align the first power rail with the output signal.
10. The invention of claim 1, wherein the power supply is further adapted to power the first amplifier using a second power rail, wherein the second power rail tracks the output signal and substantially represents another biased and half-wave rectified version of said output signal.
11. The invention of claim 10, wherein the power supply is adapted to generate each of the first and second power rails based on the input signal.
12. The invention of claim 10, wherein:
the first power rail is a positive power rail substantially representing a positively biased and positively half-wave rectified version of the output signal; and
the second power rail is a negative power rail substantially representing a negatively biased and negatively half-wave rectified version of the output signal.
13. The invention of claim 1, wherein the first amplifier comprises:
a first stage powered by the power supply using the first power rail and adapted to generate the output signal; and
a second stage powered by the power supply using a DC power rail and adapted to generate a differential signal corresponding to the input signal and apply said differential signal to the first stage, wherein the first stage is adapted to generate the output signal based on said differential signal.
14. The invention of claim 13, wherein:
the differential signal is a differential current signal; and
the second stage is adapted to maintain a fixed quiescent current in the second stage independent of the first power rail.
15. The invention of claim 1, wherein the device is implemented as an integrated circuit and is a part of an audio amplifier adapted to drive a speaker.
16. The invention of claim 1, wherein further comprising a main amplification path having the first amplifier, wherein:
the power supply is further adapted to power the first amplifier using a second power rail, wherein the second power rail tracks the output signal and substantially represents another biased and half-wave rectified version of said output signal, the power supply comprising (i) a first power-supply path adapted to generate the first power rail based on the digital input signal and (ii) a second power-supply path adapted to generate the second power rail based on the digital input signal;
the main amplification path is adapted to process the input signal to generate an M-bit signal;
the first power-supply path is adapted to process a K-bit signal carrying K most significant bits (MSBs) of said M-bit signal, where K\u2266M, and generate the first power rail based on said K-bit signal;
the second power-supply path is adapted to process a K\u2032-bit signal carrying K\u2032 MSBs of said M-bit signal, where K\u2032\u2266M, and generate the first power rail based on said K\u2032-bit signal;
the main amplification path comprises:
an interpolator and up-sampler (IPUS) adapted to process the input signal to generate said M-bit signal; and
a digital-to-analog converter (DAC) adapted to convert said M-bit signal into a corresponding analog signal, wherein the first amplifier is adapted to amplify said analog signal to generate the analog output signal.
17. The invention of claim 16, wherein each of the first and second power-supply paths comprises:
a digital pulse-width modulator (PWM) adapted to process the respective K-bit signal a digital signal corresponding to the input signal to generate a respective clocked digital signal carrying a sequence of pulses;
a switching circuit coupled to the PWM and adapted to amplify said sequence of pulses;
a filter circuit coupled to the switching circuit and adapted to process the amplified sequence of pulses to generate the respective one of the first and second power rails; and
a delay circuit adapted to align the respective one of the first and second power rails with the output signal.
18. The invention of claim 1, wherein the first amplifier is adapted to apply the analog output signal to a digital subscriber line (DSL) to transmit data from a central office to a DSL user.
19. A method of signal amplification, comprising:
generating a first power rail using a power-supply circuit; and
powering an amplifier using said first power rail, wherein:
the amplifier is adapted to generate an analog output signal in response to a digital input signal; and
the first power rail tracks the output signal and substantially represents a biased and half-wave rectified version of said output signal.
20. The invention of claim 19, further comprising:
generating a second power rail using the power-supply circuit; and
powering the amplifier using said second power rail, wherein the second power rail tracks the output signal and substantially represents another biased and half-wave rectified version of said output signal.