Hybrid　excitation　brushless　DC　generator　(BLDCG)　and　ultracapacitor　are　very　promising　in　automotive　integrated　starter/generator　(ISG)　application.　However,　with　a　traditional　diode　rectification,　it　is　difficult　to　regulate　the　DC-link　voltage　of　BLDCG　over　a　wide　operating　range　at　low　cost.　A　controlled　rectification　method　is　proposed　to　improve　generating　capacity　of　BLDCG　with　ultracapacitor　energy　storage　at　low　speed,　winding　energy　storage　can　be　transferred　to　DC-link　bus,　and　thus　DC-link　voltage　can　be　boosted　to　the　required　value.　Steady　state　performance　in　continuous　and　discontinuous　conduction　mode　is　analyzed.　Simulation　and　experiment　results　with　ultracapacitor　and　load　resistor　prove　the　effectiveness　of　the　controlled　rectification　method.