Electric lamp and discharge devices: systems – With cathode or cathode heater supply circuit – Plural load device systems
Patent
1994-05-09
1996-05-14
Lee, Benny
Electric lamp and discharge devices: systems
With cathode or cathode heater supply circuit
Plural load device systems
315276, 315 3, 363159, H05B 4129, H02M 7538
Patent
active
055170820
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an arrangement in constituting a power supply for supplying the heating coils of a tube, in particular a traveling-wave tube, wherein a transformer and an inverter are provided in the heating circuit of the tube.
2. Prior Art
As a rule, power amplifier tubes, in particular traveling wave tubes, are operated via current limiting regulators in the heating circuit, so that the heating current cannot increase to impermissible values. Such current limiting regulators in the heating circuit are known, for example, from U.S. Pat. No. 4,267,487 or from the pamphlets "Space Amplifier at 20/30 GHz", ANT 15 06 aE, 05.84; "Traveling Wave Amplifiers (TWTAs) for Space Applications" ANT 776 841, 09.90 of the firm ANT Nachrichten-technik GmbH.
In a voltage regulator known from U.S. Pat. No. 4,257,089, the frequency of a push-pull switching regulator is varied as a function of an error voltage on the output side. Thus, with a large error deviation, less energy is transmitted to the load.
In the limitation device in accordance with U.S. Pat. No. 4,267,487, the tube is supplied with DC current. AC components are suppressed in that the voltage at the heating filament is detected and a negative feedback signal is generated which controls an impedance in the supply circuit.
In a device known from the IEEE Conf. Rec. of the 1988 18th Power Modulator Symposium, pages 269-273 "Filament Considerations for High Stability Radar", the fluctuations in the heating voltage caused by frequency changes of the heating current are suppressed by a special coil geometry of the secondary coil of a HV transformer.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a current limiter for the arrangement constituting a power supply for supplying the heating coils of a tube, in particular a traveling-wave tube, wherein a transformer and an inverter are provided in the heating circuit of the tube, which causes little additional outlay and which is particularly suited to limit the heating current when the heating coil is cold. This object is attained by reducing the frequency of the AC current from a high initial value to a lower value during the heat-up time of the tube in such a way that the change of the inductive voltage drop caused by this frequency change limits the heating current at the leakage inductance of the transformer. Preferred embodiments will be described below.
The invention is based on the following realizations: the transformer in the heating circuit of a tube, for example a traveling wave tube, has a leakage inductance which, in particular in case of a transformer which supplies a high-voltage potential, can assume considerable values. If now a relatively high frequency is selected for the AC heating current, for example 200 kHz, in the start-up phase of tube heating, when the heating coil is still cold and has a low cold resistance of, for example 1 Ohm, a large portion of the AC heating current drops off at the leakage inductance. Additional current limitation, for example in the form of a series regulator, for limiting the heating current to impermissible values is then no longer required. In the heated state the heating coil has a greater resistance of, for example 10 Ohms, and the frequency of the AC heating current can then be reduced to a lower nominal value of, for example, 10 kHz. The high initial value of the frequency of the AC heating current is advantageously adapted to the value of the leakage inductance of the transformer in such a way that no impermissibly high heating current can flow in any case.
In a further embodiment, the transformer can be supplemented by two electronic push-pull switches to form a push-pull inverter. Control of these switches can be integrated in an application specific intergrated circuit (ASIC), so that the additional outlay for realizing the invention is low.
The frequency of the AC heating current can be lowered in steps in a further embodiment, for example by an oscillator which is freq
REFERENCES:
patent: 4171514 (1979-10-01), Faxon
patent: 4255690 (1981-03-01), Lecornet
patent: 4257089 (1981-03-01), Ravis
patent: 4267487 (1981-05-01), Unetich et al.
patent: 4464611 (1984-08-01), Hasili
patent: 4538093 (1985-08-01), Melai
patent: 4701671 (1987-10-01), Stupp et al.
patent: 4816720 (1989-03-01), Nomoto et al.
patent: 4906901 (1990-03-01), Carroll
patent: 4992702 (1991-02-01), Shimizu et al.
Space Amplifier at 20/30 GHz; ANT Telecommunications Prospectus; May 1984.
Travelling Wave Tube Amplifiers (TWTAs) for Space Applications; ANT Bosch Telecom Prospectus; Sep., 1990.
"Improvement Considerations for High Stability Radar"; Gardenghi et al; pp. 269-273; Westinghouse Electric Corp.
ANT Nachrichtentechnik GmbH
Bettendorf Justin P.
Lee Benny
LandOfFree
Traveling wave tube heating coil power supply with varying frequ does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Traveling wave tube heating coil power supply with varying frequ, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Traveling wave tube heating coil power supply with varying frequ will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1898344