Current controlled inverter
First Claim
1. An inverter for producing an AC output potential from a filter containing an inductance through which current flows to a load comprising:
- first and second switches coupled in series between a pair of DC reference potentials with each switch having a conductive and a non-conductive state controlled by control signals applied to control terminals of the switch;
first and second freewheeling diodes coupled in parallel respectively between first and second terminals of the first and second switches;
a current sensor producing a load currentsignal proportional to current flowing through the inductance to the load; and
a controller, responsive to an error signal proportional to a difference between an output voltage produced by the inverter applied to the load and a signal proportional to a desired regulated output voltage of the inverter, a current reference signal varying at a frequency equal to the AC output potential and the load current signal, for producing the control signals applied to the switches which turn on the switches only when current is flowing in the freewheeling diode in parallel with the switch being turned on.
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Accused Products
Abstract
An inverter (100) in accordance with the present invention for producing an AC output potential from a filter (40) containing an inductance (42) through which current flows to a load (12) in accordance with the invention includes first and second switches (Q1 and Q2) in series between a pair of DC reference potentials with each switch having a conductive and a non-conductive state controlled by control signals applied to control terminals of the switch; first and second freewheeling diodes (46) coupled in parallel respectively between first and second terminals of the first and second switches; a current sensor (38) producing a load current signal proportional to current flowing through the inductance to the load; and a controller (102), responsive to an error signal proportional to a difference between an output voltage produced by the inverter applied to the load and a signal proportional to a desired regulated output voltage of the inverter, a current reference signal varying at a frequency equal to the AC output potential and the load current signal, for producing the control signals applied to the switches which turn on the switches only when current is flowing in the freewheeling diode parallel with the switch being turned on.
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Citations
20 Claims
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1. An inverter for producing an AC output potential from a filter containing an inductance through which current flows to a load comprising:
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first and second switches coupled in series between a pair of DC reference potentials with each switch having a conductive and a non-conductive state controlled by control signals applied to control terminals of the switch; first and second freewheeling diodes coupled in parallel respectively between first and second terminals of the first and second switches; a current sensor producing a load current signal proportional to current flowing through the inductance to the load; and a controller, responsive to an error signal proportional to a difference between an output voltage produced by the inverter applied to the load and a signal proportional to a desired regulated output voltage of the inverter, a current reference signal varying at a frequency equal to the AC output potential and the load current signal, for producing the control signals applied to the switches which turn on the switches only when current is flowing in the freewheeling diode in parallel with the switch being turned on. - View Dependent Claims (2, 3, 4, 5)
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6. A method for controlling an inverter, which produces an AC output potential from a filter containing an inductance through which current flows to a load, having first and second switches which are respectively connected in parallel with first and second free wheeling diodes comprising:
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sensing current flowing through the inductance; and generating control signals applied to the switches for turning on the switches in response to the sensed current switches only when current is flowing in the freewheeling diode in parallel with the switch being turned on. - View Dependent Claims (7, 8)
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9. A multiple phase inverter having a plurality of phases with each phase producing an AC output potential from a filter containing an inductance through which current flows to a phase load, each phase comprising:
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first and second switches coupled in series between a pair of DC reference potentials with each switch having a conductive and a non-conductive state controlled by control signals applied to control terminals of the switch; first and second freewheeling diodes coupled in parallel respectively between first and second terminals of the first and second switches; a current sensor producing a load current signal proportional to current flowing through the inductance to the load; and a controller, responsive to an error signal proportional to a difference between an output voltage produced by the phase applied to the phase load and a signal proportional to a desired regulated output voltage of the inverter, a current reference signal varying at a frequency equal to the AC output potential and the load current signal, for producing the control signals applied to the switches which turn on the switches only when current is flowing in the freewheeling diode in parallel with the switch being turned on. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. In an inverter having first and second switches in series between a pair of DC reference potentials which are switched to produce an AC output voltage, first and second freewheeling diodes coupled in parallel respectively between first and second terminals of the first and second switches with conductivity of the switches being controlled in response to comparison of current flowing in an inductance coupled to the switches with an upper current level signal and a lower current level signal, the improvement comprising:
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providing an upper current level signal which varies at a fundamental frequency of the Ac output potential which varies periodically from zero current to a positive maximum current; providing a lower current level signal which varies at a fundamental frequency periodically from current zero to a negative minimum current; and controlling conductivity of the switches by changing the conductivity of each switch in response to each time current flowing in the inductance matches the current of one of current level signals. - View Dependent Claims (20)
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Specification