This　paper　presents　a　tri-directional　piezoelectric　energy　harvester　that　is　able　to　harvest　vibration　energy　over　a　wide　bandwidth　from　three　orthogonal　directions.　The　harvester　consists　of　a　main　beam,　an　auxiliary　beam,　and　a　spring-mass　system,　with　magnets　integrated　to　introduce　nonlinear　force　and　couple　the　three　sub-systems.　Theoretical　analysis　and　experiments　were　performed　at　constant　acceleration　under　frequency　sweeps　to　acquire　frequency　responses.　The　experimental　results　show　that　the　voltage　can　achieve　more　than　2　V　over　more　than　5　Hz　of　bandwidth　with　1　M　Omega　load　in　the　three　orthogonal　directions.　(C)　2013　AIP　Publishing　LLC.