Invertor device

In an invertor device for an alternating current power unit having a direct current power source circuit, said invertor device including switching means for effecting switching control of an output from said direct current power source circuit, a sine wave-forming circuit for generating a sine wave reference signal having a predetermined frequency, a pulse width modulating circuit for subjecting said sine wave reference signal to pulse width modulation to generate a pulse width modulated signal, a switching control circuit for causing said switching means to perform said switching control based on said pulse width modulated signal from said pulse width modulating circuit, and an output circuit having a pair of output terminals and responsive to said switching control by said switching means for generating an alternating current power output having a sinusoidal waveform via said output terminals,

• the improvement comprising:
• a detecting circuit for comparing between waveforms of output alternating current voltages appearing at said output terminals of said output circuit and effecting differential amplification of said output voltages, to thereby detect a difference between said waveforms of said output alternating current voltages and to generate a signal representing said relative voltage difference;
• and
• a correcting circuit for correcting said sine wave reference signal by said signal from said detecting circuit and then supplying the resulting corrected sine wave reference signal to said pulse width modulating circuit, to thereby correct said waveforms of said output alternating current voltages appearing at said output terminals such that said waveforms become closer to sinusoidal waveforms.

In an invertor device for an alternating current power unit having a direct current power source circuit, said invertor device including switching means for effecting switching control of an output from said direct current power source circuit to generate a pair of switched outputs, a sine waveforming circuit for generating a sine wave reference signal having a predetermined frequency, a pulse width modulating circuit for subjecting said sine wave reference signal to pulse width modulation to generate a pulse width modulated signal, a switching control circuit for causing said switching means to perform said switching control based on said pulse width modulated signal from said pulse width modulating circuit, a pair of output lines connected to-an output of said switching means for transmitting said pair of switched outputs from said switching means, a filter circuit connected to said pair of output lines for converting said pair of switched outputs into an alternating current power output having a sinusoidal waveform, and a pair of output terminals connected to said filter circuit for outputting said alternating current power output from said filter circuit,

• the improvement comprising:
• a detecting circuit connected to said pair of output lines for comparing between voltages appearing at each of said pair of output lines and effecting differential amplification of said voltages, to thereby detect a relative voltage difference between said output voltages and generate a signal representing said relative voltage difference;
• and
• a correcting circuit for correcting said sine wave reference signal by said signal from said detecting circuit and then supplying the resulting corrected sine wave reference signal to said pulse width modulating circuit, to thereby correct, waveforms of output alternating current voltages appearing at said pair of output terminals such that said waveforms become closer to sinusoidal waveforms.

In an invertor device for an alternating current power unit having a direct current power source circuit, said invertor device including switching means for effecting switching control of an output from said direct current power source circuit to generate a pair of switched outputs, a sine waveforming circuit for generating a sine wave reference signal having a predetermined frequency, a pulse width modulating circuit for subjecting said sine wave reference signal to pulse width modulation to generate a pulse width modulated signal, a switching control circuit for causing said switching means to perform said switching control based on said pulse width modulated signal from said pulse width modulating circuit, a pair of output lines connected to an output of said switching means for transmitting said pair of switched outputs from said switching means, and an output circuit connected to said pair of output lines for converting said pair of switched outputs into alternating current power output having a sinusoidal waveform and supplying said alternating current power output,

• the improvement comprising:
• a detecting circuit connected to said pair of output lines for detecting a relative voltage difference between voltages appearing at each of said pair of output lines and forming a relative voltage difference signal;
• a first waveform-correcting circuit for taking out and amplifying a direct current offset component from said relative voltage difference signal for feeding back said direct current offset component to said sine wave reference signal to thereby perform offset correction thereof;
• and
• a second waveform-correcting circuit for feeding back an alternating current component of said relative voltage difference signal to said sine wave reference signal to correct and supply said sine wave reference signal to said pulse width modulating circuit, to thereby correct, in a feedback manner, the waveform of said alternating current power output such that said alternating current power output from said output circuit has a waveform closer to that of a sine wave.