Inverter apparatus
First Claim
1. An inverter apparatus for providing a periodic output signal, comprising:
- a bridge circuit having a plurality of switching elements each coupled to selectively transmit to an output thereof a first signal level when said switching element is an ON state and a second signal level when it is in an OFF state,first memory means for storing pattern data of combinations of ON state and OFF state of said respective switching elements obtained based on the PWM theory,time data outputting means for outputting time data corresponding to each said combination of said first memory means, said time data including ON time data defining the time during which said ON state of said respective switching elements is maintained and OFF time data defining the time during which said OFF state of said respective switching elements is maintained, andswitching signal outputting means responsive to said pattern data and said time data for outputting switching signals to said switching elements, said outputting means including means for selecting for said switching signal a sequence of said pattern data combinations calculated to define a cycle of said output signal for the inverter and means for maintaining each of said pattern data combinations for a time defined by the corresponding time data, whereby the period of the output AC signal cycle defined by said sequence of pattern data combinations can be made to correspond to different frequencies, said switching signals being applied to the respective switching elements of said bridge circuit from which an AC output is outputted, the frequency of said AC output being determined over the entire operating frequency range of the inverter by the total time data of said ON time data and said OFF time data is one cycle.
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Accused Products
Abstract
An inverter apparatus comprises a bridge circuit composed of a combination of a plurality of switching transistors and a microprocessor controlling turning on and turning off of these switching transistors. Patterns of combinations of ON and OFF states of respective switching transistors obtained based on the theory of PWM (pulse width modulation) are stored in a first ROM of microprocessor. Transition of the pattern for each range of 0°-30° in electrical angle is stored in a second ROM in the sequence of periods subdivided from the range. Data of the time during which the pattern to be held for each period is stored in a third ROM. The microprocessor sets the holding time data in a timer, and also outputs the ON/OFF pattern, thereby turning on or turning off of each switching transistor is controlled in accordance with the count of this timer and the ON/OFF pattern. By repeating this cycle, a switching signal which continues during one cycle of AC (range of 0°-360° in electrical angle) is given to each switching transistor. Accordingly, an AC output by the PWM system is obtainable from the bridge circuit.
29 Citations
12 Claims
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1. An inverter apparatus for providing a periodic output signal, comprising:
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a bridge circuit having a plurality of switching elements each coupled to selectively transmit to an output thereof a first signal level when said switching element is an ON state and a second signal level when it is in an OFF state, first memory means for storing pattern data of combinations of ON state and OFF state of said respective switching elements obtained based on the PWM theory, time data outputting means for outputting time data corresponding to each said combination of said first memory means, said time data including ON time data defining the time during which said ON state of said respective switching elements is maintained and OFF time data defining the time during which said OFF state of said respective switching elements is maintained, and switching signal outputting means responsive to said pattern data and said time data for outputting switching signals to said switching elements, said outputting means including means for selecting for said switching signal a sequence of said pattern data combinations calculated to define a cycle of said output signal for the inverter and means for maintaining each of said pattern data combinations for a time defined by the corresponding time data, whereby the period of the output AC signal cycle defined by said sequence of pattern data combinations can be made to correspond to different frequencies, said switching signals being applied to the respective switching elements of said bridge circuit from which an AC output is outputted, the frequency of said AC output being determined over the entire operating frequency range of the inverter by the total time data of said ON time data and said OFF time data is one cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An inverter apparatus for providing a periodic output signal which is employed for a refrigerant circuit comprising at least an evaporator, which comprises
a bridge circuit which includes a plurality of switching elements, each coupled to selectively transmit to an output thereof a first signal level when said switching element is an ON state and a second signal level when it is in an OFF state, first memory means which stores pattern data of combinations of ON/OFF states of said respective switching elements obtained based on the PWM theory, second memory means which stores time data corresponding to each said pattern combination of said first memory means and representative of the holding time during which said pattern combination is to be held, and a switching signal outputting means which outputs switching signals to said switching elements based on said pattern data from said first memory means and output of said timer means, and controls defrosting of said evaporator during time-counting operation of said timer means, said outputting means including means for selecting for said switching signal a sequence of said pattern data combinations calculated to define a cycle of said output signal for the inverter and means for maintaining each of said pattern data combinations for a time defined by the corresponding time data, whereby the period of the output AC signal cycle defined by said sequence of pattern data combinations can be made to correspond to different frequencies.
Specification