PWN controller use with open loop flyback type DC to AC converter
First Claim
1. A controller suitable for controlling an open loop flyback DC to AC converter circuit, said circuit including a transformer having a primary and a secondary, said controller comprising:
- sampling means for generating a digital number representative of the magnitude of a source of DC electrical power;
sine generator means for generating a digital representation of a sinusoidal waveform;
processing means for determining the duty cycle of a pulse width modulated (PWM) signal in accordance with the following equation ##EQU28## wherein D=duty cycle of PWM signalN=turns ratio of said transformerVIN =voltage level of said source of DC electrical powerVOUT =digital representation of a sinusoidal waveform; and
pulse width modulation means for generating said PWM signal in response to the duty cycle generated by said processing means.
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Accused Products
Abstract
A controller and ring generator circuit realized therefrom utilizing an open loop flyback topology to achieve a desired output voltage waveform. A characteristic feature of the controller is that it provides the required signals to control a ring generator circuit having an open loop fly back topology. The controller functions to generate a PWM signal that is used to switch the primary of a transformer on and off. The controller includes the necessary functionality to control the duty cycle of the generated PWM signal so as to produce a sine wave output on the secondary of the transformer. The controller also includes overcurrent protection circuitry that tracks the load current by sensing the current through the primary winding. In addition, the circuit permits negative current in the secondary by use of a synchronous rectifier circuit coupled to an additional secondary transformer winding. An output bridge circuit creates a full sine wave from the generated half wave output.
117 Citations
40 Claims
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1. A controller suitable for controlling an open loop flyback DC to AC converter circuit, said circuit including a transformer having a primary and a secondary, said controller comprising:
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sampling means for generating a digital number representative of the magnitude of a source of DC electrical power; sine generator means for generating a digital representation of a sinusoidal waveform; processing means for determining the duty cycle of a pulse width modulated (PWM) signal in accordance with the following equation ##EQU28## wherein D=duty cycle of PWM signal N=turns ratio of said transformer VIN =voltage level of said source of DC electrical power VOUT =digital representation of a sinusoidal waveform; and pulse width modulation means for generating said PWM signal in response to the duty cycle generated by said processing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A controller for controlling the operation of a DC to AC converter circuit, said circuit connected to a source of DC electrical power and having an open loop flyback topology including a transformer having a primary winding and a secondary winding, a switch coupled to said primary winding and an output bridge circuit, said controller comprising:
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sampling means for generating a digital representation of the voltage level of said source of DC electrical power; sine generator means for generating a digital representation of a sinusoidal waveform; processing means for determining the duty cycle of a pulse width modulated (PWM) signal in accordance with the following equation ##EQU29## wherein D=duty cycle of PWM signal N=turns ratio of said transformer VIN =voltage level of said source of DC electrical power VOUT =digital representation of a sinusoidal waveform; pulse width modulation means for generating said PWM signal in response to the duty cycle generated by said processing means, said PWM signal output by said controller and input to said switch; and bridge control means for generating a bridge control signal output by said controller and input to said output bridge circuit, said output bridge circuit operative to convert a half wave sine function to a full wave sine function subsequently output by said circuit. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of controlling a DC to AC converter circuit having an open loop flyback topology, said circuit including a transformer having a primary and a secondary, said method comprising the steps of:
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generating a digital number representative of the magnitude of a source of DC electrical power; generating a digital representation of a sinusoidal waveform; determining the duty cycle of a pulse width modulated (PWM) signal in accordance with the following equation ##EQU30## wherein D=duty cycle of PWM signal N=turns ratio of said transformer VIN =voltage level of said source of DC electrical power VOUT =digital representation of a sinusoidal waveform; and generating said PWM signal in response to the duty cycle generated by said processing means. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
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34. A method of controlling a DC to DC converter circuit having an open loop flyback topology, said circuit including a transformer having a primary and a secondary, said method comprising the steps of:
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generating a digital number representative of the magnitude of a source of DC electrical power; generating a digital representation of the desired output voltage; determining the duty cycle of a pulse width modulated (PWM) signal in accordance with the following equation ##EQU31## wherein D=duty cycle of PWM signal N=turns ratio of said transformer VIN =voltage level of said source of DC electrical power VOUT =digital representation of the desired output voltage; and generating said PWM signal in response to the duty cycle generated by said processing means. - View Dependent Claims (35, 36, 37, 38, 39, 40)
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Specification