Detection of asymmetrical load in an AC circuit
AssigneeKoninklijke Philips Electronics N.V.
InventorEric Bertrand Shen
Life of this patent
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Abstract
A circuit for detecting if a load supplied with a high frequency AC power source is asymmetrical. The input voltage and a DC blocking voltage are connected to a differential amplifier circuit, and any difference in voltage is signaled. The load voltage and the DC blocking voltage are each reduced, for example, to 10% and 20%, respectively, while keeping them proportional to their respective full values.
Claims24
A circuit for the detection of an asymmetrical electrical load, comprising:
- (a) means for sampling an input voltage;
- (b) means for sampling a DC blocking voltage related to said input voltage;
- and
- (c) means for determining if the sampled input voltage and the sampled DC blocking voltage are equal.
A circuit for the detection of an asymmetrical electrical load, comprising;
- (a) apparatus for comparing two voltages, the apparatus having a positive input terminal, a negative input terminal, and an output terminal;
- (b) first connective means connected from a circuit node in electrical contact with an input voltage of the circuit to the positive input terminal;
- (c) second connective means connected from a circuit node in electrical contact with a DC blocking voltage of the circuit to the negative input terminal;
- and
- (d) a detection device connected to the output terminal to signal detection of an asymmetrical electrical load when the two compared voltages are unequal.
A method for the detection of an asymmetrical electrical load, comprising the steps of:
- (a) sampling an input voltage;
- (b) sampling a DC blocking voltage that is determined by the input voltage;
- and
- (c) determining if the sampled input voltage and the sampled DC blocking voltage are equal.
A circuit for operating an electric load, comprising:
- an input terminal for connection to a source of input voltage for the circuit,
- an output terminal for connection to the electric load,
- means coupled to the input terminal for deriving an AC supply voltage for the output terminal,
- means coupled to the output terminal for deriving a DC blocking voltage related to the input voltage at the input terminal,
- first and second means for deriving a sample of the input voltage and a sample of the DC blocking voltage, respectively, and
- means for comparing the sample of the input voltage and the sample of the DC blocking voltage so as to derive a signal indicative of a symmetrical operation of an electric load when the compared sampled voltages are unequal.
Dependencies are inferred from the claim text.