Summary: The birth of limit cycles in 3D (three-dimensional) piecewise linear systems for the relevant case of symmetric oscillators is considered. A technique already used by the authors in planar systems is extended to cope with 3D systems, where a greater complexity is involved.
Under some given nondegeneracy conditions, the corresponding theorem characterizing the bifurcation is stated. In terms of the deviation from the critical value of the bifurcation parameter, expressions in the form of power series for the period, amplitude, and the characteristic multipliers of the bifurcating limit cycle are also obtained.
The results are applied to accurately predict the birth of symmetric periodic oscillations in a 3D electronic circuit genealogically related to the classical Van der Pol oscillator.