Pulse by pulse current limit and phase current monitor for a pulse width modulated inverter
First Claim
1. An average current measuring circuit comprising:
- a first switch connected between a pair of reference potentials which has a duty cycle which is controlled by a control signal which pulse width modulates current flowing through the switch to a load to produce a series of current pulses and varies the current flowing through the switch in frequency;
a first current transformer coupled to the current flowing through the first switch for producing an output signal proportional to the current flow in individual current pulses;
a first sampling circuit, coupled to receive the output signal of the first current transformer, for sampling current magnitude at a beginning and at an end of each current pulse when the switch is turned on; and
an averaging circuit, coupled to the first sampling circuit, for producing an average signal of the sampled current magnitude at the beginning and ending of each current pulse within each current pulse of current flowing through the load.
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Accused Products
Abstract
An average current measuring circuit (40) in accordance with the invention includes a first switch (42) connected between a pair of reference potentials which has a duty cycle which is controlled by a control signal which pulse width modulates current flowing through the switch to a load and varies the current flowing through the switch in frequency; a first current transformer (44) coupled to the current flowing through the first switch for producing an output signal proportional to the current flow; a sampling circuit (46), coupled to the output signal, for sampling current magnitude when the switch is turned on; and an averaging circuit (60) coupled to the sampling circuit, for producing an average signal of successive samples of a current flow through the load.
30 Citations
28 Claims
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1. An average current measuring circuit comprising:
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a first switch connected between a pair of reference potentials which has a duty cycle which is controlled by a control signal which pulse width modulates current flowing through the switch to a load to produce a series of current pulses and varies the current flowing through the switch in frequency; a first current transformer coupled to the current flowing through the first switch for producing an output signal proportional to the current flow in individual current pulses; a first sampling circuit, coupled to receive the output signal of the first current transformer, for sampling current magnitude at a beginning and at an end of each current pulse when the switch is turned on; and an averaging circuit, coupled to the first sampling circuit, for producing an average signal of the sampled current magnitude at the beginning and ending of each current pulse within each current pulse of current flowing through the load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An inverter comprising:
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first and second switches which are switched with a controlled duty cycle to produce a series of current pulses defining a fundamental frequency varying from zero up to a predetermined frequency; first and second current transformers which respectively sense current flow in individual current pulses from the first and second switches to a load; and an averaging circuit, coupled to the current transformers, for producing an average of current flow at a beginning and at an ending of each current pulse of current flow within the current pulses which is used for controlling the duty cycle. - View Dependent Claims (26, 27, 28)
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Specification