High Efficiency Commutation Circuit
First Claim
1. A commutation circuit comprising:
- a coil connected to an H bridge, the H bridge comprising four main switches for reversing polarity and a resulting coil current in the coil,a voltage source configured to generate a bypass current, and at least one auxiliary switch for controlling the bypass current to thereby decrease a switch current through at least one of the main switches,wherein the commutation circuit is configured to decrease the switch current through at least one of the main switches without turning on any of the remaining main switches.
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Accused Products
Abstract
A commutation circuit includes a coil connected to an H bridge, the H bridge including four main switches for reversing polarity and a resulting coil current in the coil. The commutation circuit further includes a voltage source configured to generate a bypass current, and at least one auxiliary switch for controlling the bypass current to thereby decrease a switch current through at least one of the main switches. By generating an appropriate bypass current with help of a voltage source, a switch current through a desired main switch in a leading state can be decreased and eventually brought to zero. Zero current in its turn enables the use of thyristors as main switches as it results in the thyristors to be turned off automatically. Furthermore, decreased switch current at the switching moment reduces switching losses even in different types of switches such as GTOs and IGBTs.
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Citations
19 Claims
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1. A commutation circuit comprising:
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a coil connected to an H bridge, the H bridge comprising four main switches for reversing polarity and a resulting coil current in the coil, a voltage source configured to generate a bypass current, and at least one auxiliary switch for controlling the bypass current to thereby decrease a switch current through at least one of the main switches, wherein the commutation circuit is configured to decrease the switch current through at least one of the main switches without turning on any of the remaining main switches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 16, 17, 18, 19)
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10. An electrical machine comprising a commutation circuit including:
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a coil connected to an H bridge, the H bridge comprising four main switches for reversing polarity and a resulting coil current in the coil, a voltage source configured to generate a bypass current, and at least one auxiliary switch for controlling the bypass current to thereby decrease a switch current through at least one of the main switches, wherein the commutation circuit is configured to decrease the switch current through at least one of the main switches without turning on any of the remaining main switches.
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11. A method for reversing a current direction in a coil, the method comprising the steps of:
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providing a coil connected to an H bridge, the H bridge comprising four main switches; and generating a bypass current and controlling it to thereby decrease a switch current through at least one of the main switches without turning on any of the remaining main switches. - View Dependent Claims (12, 13, 14, 15)
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Specification