Abstract
This work describes the design and testing of a power Voltage-Controlled Current Source (VCCS) based on the Howland Current Source (HCS) topology. This source is part of a system that contains a three-axial Helmholtz coil and is used to generate a controlled magnetic field environment for aerospace applications. Initially, the paper presents the HCS theory and practical limitations on the premise that the system must be built using low-cost off-the-shelf components. The paper also carefully address on how to design and plan the VCCS matching physical and electrical parameters/limitations of a specific Helmholtz coil. All project details as well as the built VCCS electronics and its results are shown. These include linearity and a first order calibration test, stability and low-frequency error measurement, step response and a frequency limitation analysis. The built source is capable of sourcing up to ±1.5 A at ±25 V, maintaining its linearity and achieving an error smaller than 0.5% with a first order calibration. The final HCS prototype together with the Helmholtz coil allows an excellent capability regarding magnetic field generation for both open and closed-loop applications.
Highlights
The Helmholtz coil is a valuable tool to obtain constant and controllable magnetic fields
This paper outlines the design of a voltage controlled current source (VCCS) tailored to power that Helmholtz coil
It is worth mentioning that most of similar Helmholtz coil works in the literature either do not discuss the current source [5], or uses custom-built solutions based on switching inverting topologies [3], [15], or end up using commercial sources [6], which can be expensive and might not strictly comply with the system’s requirements
Summary
The Helmholtz coil is a valuable tool to obtain constant and controllable magnetic fields. It is desired that the source does not have filters or compensators that could end up compromising the HIL setup due to delays in the magnetic field response In this direction, this paper outlines the design of a voltage controlled current source (VCCS) tailored to power that Helmholtz coil. It is worth mentioning that most of similar Helmholtz coil works in the literature either do not discuss the current source [5], or uses custom-built solutions based on switching inverting topologies [3], [15], or end up using commercial sources [6], which can be expensive and might not strictly comply with the system’s requirements. The methodology presented here can be used, regardless of the application, to parameterize the HCS to match the specific needs of any system
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