Study on the Four-Quadrant Magnetic Field Modulation and Power Ratio Between Permanent Magnet and Magnetic Field Modulation in a Tangential Concentrated Magnetic Hybrid Excitation Generator

Hybrid excitation generators, which combine the advantages of permanent magnet generators and electrically excited generators, are gaining increasing attention as a research focus. Hybrid excitation generators (HEGs) consist of a Permanent Magnet Machine Part (PMMP) and a Flux Modulation Machine Part (FMMP). However, studies on the ratio relationship between the modulation power (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{P}_{\mathbf{F M}}$</tex>) of the flux modulation machine and the permanent magnet power (P <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_{\text {PM }}$</tex>), especially regarding the effects of the magnitude and direction of excitation current (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$I_{f}$</tex>) and excitation voltage (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$U_{f}$</tex>) under a constant <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{\text{PM}}$</tex>, remain limited. Using a tangential concentrated magnetic parallel structure hybrid excitation generator (TMPS-HEG) as an example, this study presents an analysis of the field-circuit coupled generation system, operational principles, and voltage phasor diagrams. The four-quadrant operational characteristics of the FMMP are examined, and based on both no-load and rated voltage references, the variation of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{P}_{\text {FM }}$</tex> under different load types and load currents is analyzed while maintaining constant <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{P}_{\boldsymbol{P} \mathbf{M}}$</tex>. The ratio <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{F M} / P_{P M}$</tex> is also calculated. Simulation results indicate that, with no-load voltage as the reference, the FMMP operates in the first quadrant for resistive and inductive loads and in the third quadrant for capacitive loads, with the ratio <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{P}_{\mathbf{F M}} / \boldsymbol{P}_{\mathbf{P M}}$</tex> remaining below 0.041 for inductive loads, higher than that for other load types. Using the rated voltage as the reference, the FMMP operates in the first, second, and third quadrants under resistive loads, in the first, third, and fourth quadrants under inductive loads, and in the third quadrant under capacitive loads. The ratio <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{\text {FM }}$</tex> / <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{\text {PM }}$</tex> remains below 0.063 for capacitive loads, again higher than for other load types. These findings indicate that for identical load currents, a relatively small <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{P}_{\mathbf{F M}}$</tex> is sufficient to stabilize the generator's output voltage.