Abstract:
To reduce power loss in an intermediate bus architecture power system, an intermediate bus converter is provided which converts an input voltage to an intermediate bus voltage using a converting unit; receives a signal indicative of an output of a converting unit; determines an intermediate bus voltage to reduce power loss in dependence upon the signal indicative of an output of the converting unit; generates a control signal to control the converting unit to convert the input voltage to the determined intermediate bus voltage; and generates an intermediate bus voltage in dependence upon the control signal.
Abstract:
A switched mode power supply (SMPS) comprising a feedback unit, voltage feed forward (VFF) compensation signal generator (1211) and a transient detector (701) is disclosed. A VFF compensation signal is only applied to the output of the feedback unit when a transient is detected by the transient detector (701) on the input voltage of the SMPS, thereby a saving power and computation time. The transient detector (701) comprises a first comparator (402) to detect that a positive transient has occurred if a difference signal is greater than a positive threshold level Cb1Q); a second comparator (403) to determine if the difference signal is within a predetermined range of positive values and output a result that indicates if the difference signal is within the predetermined range of positive values; and a first calculator (405) to detect that a positive transient has occurred if, out of a first predetermined number (N1) of consecutive results of the output of the second comparator (403), there is at least a second predetermined number (X1) of results indicating that the difference signal is within the predetermined range of positive values. The transient detector comprises further features for similarly detecting a negative transient. The transient detector (701) is particularly good at dealing with measurement noise and light load induced noise.
Abstract:
An isolated switched mode power supply, SMPS, comprising: a switching controller (230) operable to generate startup switching control signals during start-up of the isolated SMPS (200), and operational switching control signals of period T during subsequent operation of the isolated SMPS (200); a transformer (110) having a primary winding (111); and a full-bridge drive circuit arranged to drive the primary winding (ill) of the transformer in response to the switching control signals. The full-bridge drive - circuit has: a first switching element (Q2); a boot-strap driving circuit (120) arranged to switch the first switching element (Q2) in response to the switching control signals, the boot-strap driving circuit having a boot-strap capacitor; and a second switching element (Q4) connected to the first switching element (Q2) and to the boot-strap driving circuit (120), and arranged to conduct a current to charge the boot-strap capacitor when switched ON in response to the switching control signals. The switching controller (230) is operable to start up the isolated SMPS by: determining a duty cycle D for the operational switching control signals based on a voltage (V t) at an output of the isolated SMPS; and generating the start-up switching control signals comprising a first voltage pulse of duration PI to temporarily switch ON the second switching element (Q4), and a subsequent second voltage pulse of duration P2 to temporarily switch ON the first switching element (Q2), wherein P1