Power conditioner

An Electronic Power Conditioner (EPC ) is used a traveling wave tube with the required operating voltages to supply and forms together with this, a traveling wave tube amplifier. If even the accompanying pre-amplifier built into the EPC, it is called a Microwave Power Module ( MPM).

Function

The general function of an EPC can be represented as follows: The power supply ( EPC) has the task safely operate a traveling wave tube ( TWT) and a preamplifier under all operating conditions and to protect both devices in case of failure. Thus, the EPC has to assume different functions, which must be made between primary and secondary functions.

Primary functions:

  • Highly efficient generation of the required for the operation of the traveling-wave tube high voltage from the variable, floating and much lower input voltage.

Secondary functions:

  • Generation of telemetry signals and adapt to the satellite system
  • Control of internal processes that are required for the insertion of a traveling wave tube
  • Adjusting the necessary parameters for the corresponding service tube
  • Protection circuits to protect the traveling wave tube unsafe practice or high voltage flashovers
  • Adjustment of the tele command interface to the satellite system
  • Generation of auxiliary voltages for channel amplifier with linearizer.

Block diagram

The block diagram of the analog and partly digital solution previously used is shown in the following block diagram.

Operation

Floating the input voltage ( VMB ) is fed to a pre-regulator which converts the input voltage into a constant output voltage (VB). This primary controller is one of the key components of the EPC, which influences various Hauptparamter the EPC and the traveling wave tube. The main features of the controller are high efficiency, high noise immunity to conducted disturbances, high regulator stability and insensitivity to pulsed loads. All these properties are best met by a buck regulator, a Switch Mode Power Supply (SMPS ).

To suppress the switching regulator Eingangsspannungswelligkeit and disorders of the EPC, an input filter is inserted between the power switch of the primary controller and the EPC power input.

A start-up series regulator, the voltage to the internal electronics. It switches off automatically when the auxiliary voltage converter operates.

The constant output voltage (VB) is the Heizkonverter fed directly and produces a square voltage for the traveling wave tube heating. Another voltage regulation is not required, but the Heizkonverter requires a soft-start circuit to avoid inrush current in cold tube heater.

The supply voltages for the channel amplifier is generated by an auxiliary power converter with an internal overload protection.

The main converter is supplied and produced by its push-pull stage, a square wave output voltage by this constant voltage ( VB). The main characteristics of the push-pull converter is its high efficiency, optimized and low-loss Umschwingverhalten the HV transformers, avoiding the overlapping switching of said switching transistors by a defined gap period and a soft ring-around the high voltage diodes.

An important part of the power path is the high voltage generator.

The type of high-voltage generation and their continuation to the traveling-wave tube affect the traveling wave tube behavior long term. With the output filter design, the tube can be turned on simultaneously with all the high voltages without current peaks occur in the helix current of the traveling wave tube. By a serial high-voltage approach, i.e., the production of all high voltages with only one high-voltage transformer and connected in series to the collector doubling stages, helical and anode voltages, the high standards can be achieved most efficiently on the EPC. The stability of the collector voltages is determined only by the Vorreglerausgangsspannung (VB). Additionally, the helix and the anode voltage can be stabilized by the series regulator, to ensure a constant high-frequency behavior of the traveling-wave tube. The Helix controller chassis potential and the cathode current controller at anode potential.

All internal processes of the EPC are controlled by the digital control unit. This function block is integrated normally in an application specific integrated circuit ( ASIC) and has the following tasks:

  • Generating the clock frequency
  • Generating the control signals for the heating, main and auxiliary voltage converter
  • Control the startup of the high voltages
  • Preparation of the telecommand signals
  • Generation of telemetry status signal
  • Protection of EPC against malfunctions including automatic restart unit ( ARU).

Areas of application

The "heart " for communications satellites are power amplifiers. Their purpose which there accumulating data either to ground or to other communications satellites to transmit. Nowadays, inter alia, the company produces TESAT Spacecom such EPCs and integrates them with traveling wave tubes manufactured by Thales Air Systems and Electron Devices for traveling wave tube amplifiers.

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