Four-quadrant pulse width modulated DC/AC converter
AssigneeItaltel Societa Italiana Telecomunicazione S.p.A.
InventorsCimador Giuseppe, Prestifilippo Paolo
Life of this patent
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Abstract
A pulse width modulated DC/AC converter includes an input circuit galvanically insulated from an output circuit. The input circuit includes two branches connected in parallel to a pair of input terminals which receive a direct current voltage. Each branch includes an inductor, and a bidirectional switching element which may include a transistor in parallel with a diode. The output circuit has a similar configuration with the addition of two filtering capacitors connected across the output terminals. The converter has a wide range of applications, such as a ringing generator in a telephone system, an emergency supply for a computer system, or as a driving stage for a AC motor.
Claims16
A DC/AC converter for supplying an alternating output voltage to a load comprising:
- an input circuit having two input terminals connected to a direct current source;
- an output circuit having a pair of output terminals connected across the load and being galvanically insulated from said input circuit;
- said input circuit including,
- a first inductor and first switching means connected in series across said input terminals;
- a second conductor and second switching means connected in series across said input terminals;
- said output circuit including:
- a third inductor and third switching means connected to said load through filter means;
- a fourth inductor and fourth switching means connected to said load through filter means;
- said first and third inductors being magnetically coupled together and said second and fourth inductors being magnetically coupled together;
- said third inductor and switching means, and said fourth inductor and switching means being connected to the output terminals;
- said filter means being connected between the output terminals and a common node connecting said third and fourth switching means;
- each of said switching means comprising a unidirectional semiconductor switch connected in parallel with a diode, the control electrodes of said first and third semiconductor switches and the control electrodes of said second and fourth semiconductor switches receiving from said control means signals that are out of phase by 180.degree., respectively.
A DC/AC call signal generator for supplying an alternating output voltage to a load comprising:
- an input circuit having two input terminals connected to a direct current source;
- an output circuit having a pair of output terminals connected across the load and being galvanically insulated from said input circuit;
- said input circuit comprising:
- a first inductor and first switching means connected in series across said input terminals,
- a second inductor and second switching means connected in series across said input terminals,
- said output circuit comprising,
- a third inductor and third switching means connected to said load through filter means,
- a fourth inductor and fourth switching means connected to said load through filter means;
- said first and third inductors being magnetically coupled together and said second and fourth inductors being magnetically coupled together, the call signal generator further comprising means for generating control signals for said switching means;
- said third inductor and switching means and said fourth inductor and switching means being connected to the output terminals,
- said filter means being connected between the output terminals and a common node connecting said third and fourth switching means;
- each of said switching means comprising a unidirectional semiconductor switch connected in parallel with a diode, the control electrodes of said first and third semiconductor switches and the control electrodes of said second and fourth semiconductor switches receiving from said control means signals that are out of phase by 180.degree., respectively.
Dependencies are inferred from the claim text.