摘要:
In any steady-state optimization problem, the output being optimized could be a nonmonotonic function of the controlled variable. Often the output is dependent on the temperature, the load impedance, and other unknown and variable quantities. Thus, it is very useful to have an automatic tuning scheme that will take the system to the desired operating point using only input and output information. The present invention is a generalized tuning scheme that uses the correlation between changes in the input and corresponding changes in the output to tune the operating point. In general terms, the present invention utilizes a correlation function between the controlled variable and a perturbed waveform. When the system reaches the desired operating point, the correlation goes to zero and the system converges. This corresponds to the point at which the derivative of the output with respect to the input is zero. This tuning scheme is appropriate for any tuning problem which has a single maximum or minimum. A variety of tuning problems in power electronics and other areas fall into this category. A tuning scheme based on correlation usually requires an excitation input. The switching action in the controlled circuit perturbs all the states and provides this excitation. Thus, this tuning scheme is appropriate for switching power applications. A preferred embodiment of the present application is used to control a power converter in a solar array application.
摘要:
An active filter provides ripple cancellation in a DC-DC converter. The feedforward filter applies to any converter with an output filter inductor. The filter is inherently stable, performs in both continuous and discontinuous conduction modes, and applies to resonant converters. A suitable linear amplifier, combined with a current transformer, results in a low loss implementation. An adaptive tuning scheme compensates for inductance variation and drift. The filter is usable with buck, push-pull, and boost converter topologies. The result is output ripple below 10 mV.sub.RMS. The filter is effective on converters with outputs as low as 2 V and currents beyond 30 A.
摘要:
A system according to one embodiment includes a digital data modulator configured to generate encoded symbols; an envelope detector configured to receive the encoded symbols and to estimate transmission power information associated with the encoded symbols; a peak detector configured to receive the transmission power information, detect a peak transmission power from two or more sequential data points of the received transmission power information, and to generate a power regulation signal representative of the detected peak transmission power; and a digital to analog converter (DAC) configured to receive the power regulation signal and to provide a reference voltage to a power supply associated with an RF amplifier.
摘要:
A switching amplifier includes a power stage, a low pass filter, a combining circuit, and a feedback correction circuit. The power stage has an input terminal and an output terminal. The low pass filter has an input terminal coupled to the output terminal of the power stage, and an output terminal for providing a filtered pulse width modulated signal. The combining circuit has a first input terminal coupled to the output terminal of the power stage, a second input terminal coupled to the output terminal of the low pass filter, and an output terminal. The feedback correction circuit has a first input terminal for receiving a reference pulse width modulated signal, a second input terminal coupled to the output terminal of the combining circuit, and an output terminal coupled to the input terminal of the power stage.
摘要:
A system is described for generating a discrete noise-shaped variable switching frequency signal that may be used to define a digital pulse width modulation (“PWM”) period. The system may define a switching frequency waveform that may be used to generate a current switching frequency signal as a function of a system clock. The system may quantize the current switching frequency signal to generate a discrete switching frequency signal that is realizable with the system clock. The system may detect quantization noise and input the noise into the current switching frequency signal to eliminate or reduce discrete tones at the switching frequencies of a PWM signal spectrum.
摘要:
A closed loop audio amplifier system and method of powering up/down the system without producing audible artifacts are provided. During power up, a prebias voltage is provided to each output connected to a speaker to increase the voltage to a nominal output level. High impedance switches are then driven at a 50% duty cycle. Feedback from the output is supplied to a servo, which is enabled to fine tune the output voltage. Low impedance switches are then driven at a 50% duty cycle at a quarter cycle timing. The order of the feedback loop depends on which of the high or low impedance switches are driven. The prebias voltage is then removed before audio signals to be amplified are supplied to the system. Timing of driving of the switches is programmable. To power down, essentially the reverse sequence is provided.
摘要:
An audio amplifier includes a digital signal processor (DSP) that contains a noise shaping quantizer having an integrating error amplifier. The integrating error amplifier contains integrators connected in a feedback loop, a summer supplied with an output of each of the integrators, and a saturation function module producing a saturation function. A multiplier is disposed between each pair of adjacent integrators. The multiplier receives a signal from one of the adjacent integrators and the saturation function and supplies a signal to the other of the adjacent integrators. The saturation function decreases the effect of all of the integrators except an integrator to which an input signal to the integrating amplifier is supplied using an input signal to and/or an output signal from the noise shaping quantizer. This permits the duty ratio of the output signal from the noise shaping quantizer to extend from 0% to 100%.
摘要:
A system and method for analog-to-digital conversion using digital pulse width modulation (PWM) is disclosed. The method and system according to the disclosed invention converts an analog input signal to a digital signal in pulse code modulated (PCM) form. The disclosed invention uses a feedback circuit to perform PWM of the analog input signal. The PWM signal is then decimated to obtain the digital signal in PCM form. The system according to the disclosed invention requires lower operating frequency and dissipates lesser power than prior art systems providing the same sampling frequency and resolution. The operation at a lower frequency is achieved by obtaining two samples from every pulse of the PWM signal; the first sample being obtained from the right duty ratio, and the second sample being obtained form the left duty ratio. Further, the disclosed invention has lesser implementation complexity and higher signal-to-noise ratio than prior art.
摘要:
Disclosed is a method and/or apparatus for adjusting the sample time and order associated with a digital correction system for maximizing output power and minimizing power stage delay sensitivity of a switching power stage. In certain embodiments, the sample point of an ADC may be changed as a function of the duty ratio of the PWM signal thus allowing higher performance and use of less expensive power stage components. In addition, adjustment of the order of an integrating error amplifier in the system permits operation of the power stage with an output being permitted to saturate up to the power supply rails, thus increasing a power output of the power stage.
摘要:
A power amplifier circuit for receiving a variable envelope input signal and for producing an amplified output signal is provided. The power amplifier circuit includes an envelope approximation circuit, an envelope amplifier circuit, a phasor approximation circuit, a quadrature modulation circuit, and a power amplifier. The envelope approximation circuit receives the variable envelope input signal and produces a bandlimited estimated envelope signal, corresponding to the amplitude of the variable envelope input signal. The bandlimited estimated envelope signal is then amplified by an envelope amplifier circuit. The amplified envelope signal is then coupled to the supply input of the power amplifier. The phasor approximation circuit receives the variable envelope input signal and produces a bandlimited estimated phasor signal. The quadrature modulation circuit receives the estimated phase signal and produces a modulated phase signal. The modulated phase signal is then coupled to the signal input of the power amplifier. The power amplifier then produces an amplified output signal.