Coil excitation arrangement for producing a pulse-shaped field of constant intensity
US4470095A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 29, 1982 |
| Grant date | Sep 4, 1984 |
| Priority date | — |
| Expiry date | Mar 29, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/04113
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An embodiment of the present invention provides an excitation arrangement suitable for use in producing a pulse-shaped field of substantially constant intensity. To start-up the current at the beginning of a pulse, a coil (1) is fed with a high voltage (line 3) via an ignitable and blockable power semiconductor (7). For the duration of the pulse, switch-over is then effected to the supply of a lower voltage (line 4) by means of a power transistor (31) controllable to a constant current. Free-running diodes are used to decay the current. One coil end (2) is preferably connected via an FET (7) which is controllable to a constant voltage, to the high voltage; via an FET (30), which is likewise controllable to a constant voltage, to the lower-voltage (4); and via a controllable FET (52) to a reference line (6). Corresponding FET's (50, 51, 31) are provided at the other coil end (5). The controllable FET's (51, 52) require no potential-isolated control, and moreover, the power-FET's do not require their own additional free-running diodes (mentioned above) due to their inherent diode characteristic for currents flowing in the blocking direction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.