Switching mode power supplies
First Claim
1. A switching mode power supply comprising:
- an inductance;
a switch having alternating ON and OFF periods for coupling an input voltage to said inductance during said ON periods to cause a current to flow in said inductance;
a rectifier for coupling the current flowing through said inductance to an output during the OFF periods of said switch, each of said switch and said rectifier having a respective current flowing therethrough and each said current having a respective root-means-square (RMS) value, one of said switch or said rectifier having a smaller RMS current value than the other thereof; and
means for determining the current flowing through said inductance, said means including a current-sensing resistor coupled in series with the one of said switch or said rectifier having the smaller RMS current value for measuring the current flowing therethrough, and a current-sensing transformer coupled in series with the one of said switch or said rectifier having the larger RMS current value for measuring the current flowing therethrough, said current-sensing resistor and said current-sensing transformer generating respective representations of the sensed currents flowing therethrough such that said respective representations are combinable to provide a representation of the current flowing through said inductance.
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Abstract
A switching mode power supply is disclosed in which an input voltage is modulated by a switch and the modulated waveform is passed through an inductance, rectified and filtered to provide an output of a controlled value, and in which to determine the current passing through the inductance, the smaller of the root mean square (rms) current through the switch and the rms current through the rectifier is measured by including a current measuring resistor in series with that respective component, and the current through the other component is measured by including a current-sensing transformer in series with that component, the current through the inductor then being determinable as the combination of the other two currents.
107 Citations
11 Claims
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1. A switching mode power supply comprising:
- an inductance;
a switch having alternating ON and OFF periods for coupling an input voltage to said inductance during said ON periods to cause a current to flow in said inductance;
a rectifier for coupling the current flowing through said inductance to an output during the OFF periods of said switch, each of said switch and said rectifier having a respective current flowing therethrough and each said current having a respective root-means-square (RMS) value, one of said switch or said rectifier having a smaller RMS current value than the other thereof; and
means for determining the current flowing through said inductance, said means including a current-sensing resistor coupled in series with the one of said switch or said rectifier having the smaller RMS current value for measuring the current flowing therethrough, and a current-sensing transformer coupled in series with the one of said switch or said rectifier having the larger RMS current value for measuring the current flowing therethrough, said current-sensing resistor and said current-sensing transformer generating respective representations of the sensed currents flowing therethrough such that said respective representations are combinable to provide a representation of the current flowing through said inductance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- an inductance;
Specification