Controlled power dissipation in a lighting system
First Claim
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1. An apparatus comprising:
- a controller configured to generate a first control signal to control a flyback switch coupled to a primary-side transformer coil in an output stage of a switching power converter in a phase cut compatible, dimmable lighting system, wherein the controller is further configured to generate a second control signal to control a power dissipation circuit coupled in series with the flyback switch to dissipate excess energy in the flyback switch during a controlled power dissipation phase, and the controlled power dissipation phase exclusively occurs after a charging phase begins and before an end of a subsequent flyback phase of the switching power converter, wherein the excess energy comprises more energy than an amount of energy to be provided to a load coupled to the switching power converter plus inherent energy losses.
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Abstract
In at least one embodiment, a lighting system includes one, some, or all of a switch path, link path, and flyback path power dissipation circuits to actively and selectively control power dissipation of excess energy in a switching power converter of the lighting system. The flyback path power dissipation circuit dissipates power through a flyback path of the switching power converter. In at least one embodiment, the lighting system controls power dissipation through the flyback path by controlling a transformer primary current in the flyback path and, for example, limiting the primary current with a current source and dissipating power in the flyback switch and the current source.
117 Citations
31 Claims
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1. An apparatus comprising:
a controller configured to generate a first control signal to control a flyback switch coupled to a primary-side transformer coil in an output stage of a switching power converter in a phase cut compatible, dimmable lighting system, wherein the controller is further configured to generate a second control signal to control a power dissipation circuit coupled in series with the flyback switch to dissipate excess energy in the flyback switch during a controlled power dissipation phase, and the controlled power dissipation phase exclusively occurs after a charging phase begins and before an end of a subsequent flyback phase of the switching power converter, wherein the excess energy comprises more energy than an amount of energy to be provided to a load coupled to the switching power converter plus inherent energy losses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus comprising:
a controller configured to control a flyback switch coupled to a primary-side transformer coil in an output stage of a switching power converter in a phase cut compatible, dimmable lighting system, wherein the controller is further configured to control the flyback switch in an efficient mode and a power dissipation mode, wherein in the efficient mode, the controller is configured to operate the flyback switch to minimize power dissipation in the flyback switch and in the power dissipation mode the controller is configured to operate the flyback switch to increase dissipation of energy in the flyback switch, relative to any power dissipation in the flyback switch during operation in the efficient mode, to dissipate excess energy representing more energy than an amount of energy to be provided to a load coupled to the switching power converter plus inherent energy losses, wherein in the efficient mode the controller is configured to generate a control signal to cause a charging current to flow through the flyback switch during a charging phase of the switching power converter and cut-off current through the flyback switch during a flyback phase during the efficient mode and is further configured to limit current through the flyback switch to an intermediate value between the charging current and zero during the power dissipation mode. - View Dependent Claims (13, 14, 30)
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15. A method comprising:
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controlling with a first control signal a flyback switch coupled to a primary-side transformer coil in an output stage of a switching power converter in a phase cut compatible, dimmable lighting system; and controlling with a second control signal a power dissipation circuit coupled in series with the flyback switch to dissipate excess energy in the flyback switch during a controlled power dissipation phase, and the controlled power dissipation phase occurs exclusively after a charging phase begins and before an end of a subsequent flyback phase of the switching power converter, wherein the excess energy comprises more energy than an amount of energy to be provided to a load coupled to the switching power converter plus inherent energy losses. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 31)
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27. A method comprising:
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controlling a flyback switch coupled to a primary-side transformer coil in an output stage of a switching power converter in a phase cut compatible, dimmable lighting system; and controlling the flyback switch in an efficient mode and a power dissipation mode, wherein controlling the flyback switch in the efficient mode comprises; operating the flyback switch to minimize power dissipation in the flyback switch; generating a control signal to control conductivity of the flyback switch; generating the control signal using two states in the efficient mode; and generating the control signal using at least three states in the power dissipation mode, wherein the at least three states in the power dissipation mode occur during a time beginning with a charging phase of the primary-side transformer coil and an end of an immediately subsequent flyback phase of the primary-side transformer coil; and wherein controlling the flyback switch in the power dissipation mode comprises; operating the flyback switch to increase dissipation of excess energy in the flyback switch relative to any power dissipation in the flyback switch during operation in the efficient mode, wherein the excess energy comprises more energy than an amount of energy to be provided to a load coupled to the switching power converter plus inherent energy losses. - View Dependent Claims (28, 29)
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Specification