PWM Inverter device
AssigneeToyo Denki Seizo Kabushiki Kaisha
InventorsMasakazu Kohata, Hideki Hayashi, Ichiro Miyashita
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Abstract
An inverter device operating under pulse width modulation (PWM) principle in which chopping pulse is formed by crossing points of a triangle waveform and a function waveform in order that pulse width of the inverter input current decreases towards later half of pulse train in each period of pulse repetition series.
Claims5
A PWM inverter device for energizing ac motor with variable voltage and variable frequency output obtained from a dc current source by pulse width adjustment, characterized in that the device comprises an oscillator for generating a series of output pulses synchronized with output frequency of the inverter and having frequency integral multiple of the output frequency, a function waveform generator for generating level signal having frequency of 2m times (m being an integer representing the number of phases of the inverter device) of the inverter output frequency in response to the output of said oscillator, a triangle waveform oscillator for generating triangle wave shaped carrier signal having a constant frequency at least 12 times with that of the inverter signal, a modulator for comparing and mixing said level signal with said carrier signal, wherein said level signal is generated in a functional form in order that the pulse width of the inverter output voltage decreases monotonically and forms repeated waveforms by a chopping instruction of the modulator output.
A PWM inverter device for energizing ac motor with variable voltage and variable frequency output obtained from a dc current source by pulse width adjustment, characterized in that the device comprises an oscillator for generating a series of output pulses synchronized with output frequency of the inverter and having frequency integral multiple of the output frequency, a function waveform generator for generating level signal having frequency of 2m times (m being an integer representing the number of phases of said inverter device) of the inverter output frequency in response to the output of said oscillator, a triangle waveform oscillator for generating triangle wave shaped carrier signal having a constant frequency at least 12 times with that of the inverter output signal, a modulator for comparing and mixing said level signal with said carrier signal, wherein during a period from starting time to a time when the inverter input frequency passes a certain predetermined frequency said level signal is generated in a functional waveform in order that the pulse width of the inverter output voltage decreases monotonically to form repeating waveforms by the chopping instruction.
Dependencies are inferred from the claim text.