Power supply with tickle pulse injection
AssigneeBose Corporation
InventorsKenneth B. DelPapa, Michael Nussbaum, Andrew Ferencz
Life of this patent
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Abstract
A power supply injects a series of “tickle” pulses into a pulse width modulated (PWM) controller to induce the controller to generate PWM pulses at a minimum switching frequency, preferably one that is super-sonic (especially for audio applications). The switching frequency may also be selected or controlled such that it avoids resonances in the power supply. The “tickle” pulses may be clocked by the same clock that times the PWM controller, and they may be shaped to help ensure that the power supply maintains some regulation during low-load conditions.
Claims25
A power supply comprising:
- an output node that is configured to deliver a target output voltage to a variable load;
- one or more power switches that controls power delivered to the output node;
- a controller configured to produce a series of variable width pulses that control operation of the power switches such that the output node delivers a near constant target output voltage to the load, wherein the controller is configured to receive an error signal indicating the difference between an actual voltage at the load and the target voltage and alter at least the width of the pulses delivered to the power switches based on a hysteretic window of the error signal;
- a tickle pulse generator configured to generate a series of tickle pulses that are combined with the error signal supplied to the controller, wherein at least some of the pulses cause the controller to generate a pulse delivered to the power switches when the load draws little or no power.
An audio system comprising:
- an audio amplifier configured to power one or more audio transducers;
- a power supply configured to deliver a target output voltage to the audio amplifier, wherein the power supply comprises:
- one or more power switches that control power delivered to the audio amplifier;
- a controller configured to produce a series of variable width pulses that control operation of the power switches such that the power supply delivers a new constant target output voltage to the audio amplifier, wherein the controller is configured to receive an error signal indicating the difference between an actual voltage at the audio amplifier and the target voltage and alter at least the width of the pulses delivered to the power switches based on a hysteretic window of the error signal;
- a tickle pulse generator configured to generate a series of tickle pulses that are combined with the error signal supplied to the controller, wherein at least some of the tickle pulses cause the controller to generate a pulse delivered to the power switches when the audio amplifier draws little or no power.
A method for controlling switching in a pulse width modulated (PWM) power supply with a variable switching frequency, the method comprising:
- obtaining a voltage error signal that represents the difference between a target voltage and an actual output voltage of the power supply provided to a load;
- generating a tickle pulse that is synchronized with a switching opportunity of a PWM controller;
- combining the tickle pulse with the voltage error signal to form a combined signal;
- and
- applying the combined signal to a control input of the PWM controller to control periods of switching and no switching in the PWM power supply by a hysteretic window of the voltage error signal.
Dependencies are inferred from the claim text.