Switching power supply
First Claim
1. A switching power supply comprising:
- a power transformer having a primary and a secondary;
a switching element for coupling a voltage source to the primary;
a current sensor that measures a primary current and a secondary current;
a rectifier coupled to the secondary adapted to conduct current to a load coupled thereto; and
a control circuit coupled to the current sensor and the switching element that controls the operation of the switching element in response to the primary current and the secondary current;
wherein when the primary current in the primary reaches a first threshold, the control circuit causes the switching element to disconnect the voltage source from the primary which stops flow of the primary current in the primary and which causes the secondary current to conduct to the load; and
wherein when the secondary current drops to a second threshold, the control circuit causes the switching element to reconnect the voltage source to the primary which terminates the secondary current flow in the secondary and which causes the primary current to flow in the primary.
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Accused Products
Abstract
Self-oscillating, current controlled switching power supplies, used for example, as energy storage device charging circuits, and related methods are provided herein. In one implementation, a switching power supply comprises a power transformer having a primary and a secondary, a switching element that switches a voltage source to the primary, and a control circuit that controls the operation of the switching element in response to the measured primary current and secondary current. The switching element disconnects the voltage source from the primary when the primary current reaches a first threshold, causing the secondary current to conduct. The switching element switches back to the primary when the secondary current drops to second threshold. The switching power supply oscillates between charging and discharging the power transformer. In one embodiment, a high value energy storage capacitor is coupled to the secondary and is charged with the secondary current.
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Citations
23 Claims
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1. A switching power supply comprising:
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a power transformer having a primary and a secondary;
a switching element for coupling a voltage source to the primary;
a current sensor that measures a primary current and a secondary current;
a rectifier coupled to the secondary adapted to conduct current to a load coupled thereto; and
a control circuit coupled to the current sensor and the switching element that controls the operation of the switching element in response to the primary current and the secondary current;
wherein when the primary current in the primary reaches a first threshold, the control circuit causes the switching element to disconnect the voltage source from the primary which stops flow of the primary current in the primary and which causes the secondary current to conduct to the load; and
wherein when the secondary current drops to a second threshold, the control circuit causes the switching element to reconnect the voltage source to the primary which terminates the secondary current flow in the secondary and which causes the primary current to flow in the primary. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A switching power supply comprising:
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a power transformer having a primary and a secondary;
a switching element for coupling a rectified AC voltage source to the primary;
a current sensor that measures a primary current and a secondary current;
a rectifier coupled to the secondary that conducts current to an energy storage capacitor to be charged by the power supply; and
a control circuit coupled to the current sensor and the switching element that controls the operation of the switching element in response to the primary current reaching a first threshold and the secondary current dropping to a second threshold; and
wherein the control circuit adjusts the first threshold based upon variations of the voltage of voltage source. - View Dependent Claims (20, 21, 22)
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23. A switching power supply comprising:
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a power transformer having a primary and a secondary;
a switching element for coupling a rectified AC voltage to the primary;
a current sensor that measures a primary current and a secondary current;
a rectifier coupled to the secondary that conducts current to a load when coupled thereto; and
a control circuit coupled to the current sensor and the switching element that controls the operation of the switching element in response to the primary current and the secondary current.
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Specification