Archive: Jul 2024

How to Prevent Voltage Droop

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Voltage droop in modulators can affect critical equipment such as particle accelerators. The droop can happen within microseconds, potentially disrupting equipment operation.

Here, we’ll explore voltage droop in more detail, why and when it occurs, and the causes of voltage droop to help you understand and prevent the effects of this phenomenon. We will also discuss innovative technology that can prevent voltage fluctuations and dips at the modulator.

 

What Is Voltage Droop?

Voltage droop is a temporary voltage output decrease that occurs in pulsed electronic devices like modulators. The voltage decrease falls below nominal or desired levels due to certain factors during operation. In modulators, the voltage can drop 1% within millionths of a second.

Ultimately, pulse droop affects the efficiency of the electron tube, which defines the overall efficiency of the system. Eliminating pulse droop lowers overall total power input for cost savings and reduces environmental impact because of that efficiency.

 

Why and When Does Voltage Drop Occur?

Voltage droop is usually preceded by a sudden increase in load demand, characterized by a sharp overshoot of voltage, followed by an abrupt drop in voltage below desired levels, usually by about 1%. All of this can happen within microseconds. Stabilization mechanisms then restore voltage to proper levels. 

Even slight droops can affect tube output. These sudden load demand increases and temporary voltage drops can cause the tube to produce inferior beams. Excess voltage can impact the energy efficiency of the system, cause overheating, and lead to equipment damage and failure. In long pulse applications, modulators need a complex voltage compensation circuit to prevent the voltage droop and maintain reliable, efficient system operation.

What Causes Voltage Drop in High-Voltage Modulators?

Marx modulators with solid-state switches are more reliable and adjustable than conventional modulators. However, when used to create long high-voltage pulses, such as those required for particle accelerators, Marx generators run into issues intrinsic to these generators. During discharge, the Marx voltage naturally decays over time. Long pulse widths or small time constants in the resistor-capacitor circuit will increase voltage reduction at the end of the pulse. 

Electrostatic accelerator free electron laser (FEL) oscillators also face issues with the amount of electron beam lost due to voltage droop as it approaches the electron tube. This quick, indiscernible drop in voltage could potentially disrupt tube output.

Voltage droop is a result of several factors in modulators. Some of the primary causes of voltage droop include:

  • Power Supply Instability: Instability and fluctuations in the voltage from the power supply to the modulator can result in voltage droop. Instability may result from insufficient supply capacity and variations from the input power source.
  • Load Changes: In military radar applications, where every pulse has a different width and amplitude, voltage droop can result from sudden changes in load from devices connected to the modulator. These load increases can come from sudden spikes in machinery power consumption or numerous appliances operating simultaneously, either of which may cause a sudden overload in the modulator and a drop in voltage. 
  • Power Source Limitations: Voltage droop may also occur when power supply sources are operating near maximum capacity.
  • Impedance Mismatch: Voltage droop can follow from a mismatch in impedance between the modulator and load, especially if the load impedance difference is significant. High impedance and resistance in the power transmission and distribution system can also cause a voltage drop as the current flows through the systems. 

 

Preventing Voltage Droop with Stangenes’ Solid-State Technology

It is critical to consider load characteristics, component selection, and power supply design to maintain modulator performance and mitigate voltage droop. Stangenes Industries’ patented pulse droop compensator is a parallel boost network that offers droop compensation for all pulse length applications. The compensator can produce a 3.2 kV/3.2 A pulse for 3.6 ms with greater than 1% stability. These adaptive circuits are built into our modulators, resulting in less than 1% droop.

This patented technology is a major milestone in the pulsed power industry, and it is suitable for users requiring electrical power for pulse generators. With Stangenes Industries’ solid-state technology, laboratories benefit from higher reliability and reduced downtime while commercial users benefit from higher profits.

Pulse Modulator Configurations Offered

  • Complete “turnkey” systems or an individual component for your system
  • Solid-state Marx designs with or without a pulse transformer
  • Dynamically adjustable repetition rate, pulse width, and pulse amplitude
  • Solid-state fractional turn pulse transformer modulators
  • “Line-type” modulator with a pulse transformer and solid-state switching
  • “Hard tube configuration” with pulse transformer using solid-state switching

 

Voltage Droop Control Solutions From Stangenes Industries

Voltage droop can result from various factors and cause detrimental effects on the quality of the pulse. It is critical to prevent voltage droop by understanding when and how it occurs and taking the appropriate precautions.

Stangenes Industries offers pulse droop control technology built into our modulators. We have been in the industry since 1974 and have grown to over 100 employees serving the manufacturing, research, medical, and military markets. We continuously deliver innovative electromagnetic equipment solutions to customers from start-ups to Fortune 500 companies. Request a quote to learn more about our modulators and voltage droop protection solutions.