Intermediate Bus Architecture with a Quasi-Regulated Bus Converter

Abstract

A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.

1 . (canceled) 
     
     
         2 . A dc-dc converter system comprising:
 an isolated dc-dc bus converter that receives a dc source voltage and converts the dc source voltage to a dc intermediate voltage output, the dc-dc bus converter:
 in normal operation, having a non-regulated mode of operation, over a low voltage portion of an operating range of the dc source voltage, where the dc intermediate voltage output is not regulated by the bus converter and the dc intermediate voltage output displays a droop characteristic; and 
 in normal operation, having a fully regulated mode of operation, over a high voltage portion of the operating range of the dc source voltage, where the dc intermediate voltage output is fully regulated by the bus converter; and 
   a plurality of non-isolated switching regulators, each receiving the dc intermediate voltage output of the dc-dc bus converter and regulating a switching regulator output.   
     
     
         3 . A dc-dc converter system as claimed in  claim 2  wherein the fully regulated mode of operation of the dc-dc bus converter creates a tightly regulated dc intermediate voltage output by feeding back a signal from the dc intermediate voltage output. 
     
     
         4 . A dc-dc converter system as claimed in  claim 3  wherein the dc-dc bus converter comprises:
 at least one transformer with at least one primary winding and at least one secondary winding; 
 a primary winding circuit that receives the dc source voltage; and 
 a secondary winding circuit having plural controlled rectifiers with parallel uncontrolled rectifiers and an output filter having an output inductor. 
 
     
     
         5 . A dc-dc converter system as claimed in  claim 4  wherein the controlled rectifiers are driven from signals derived from the at least one secondary winding. 
     
     
         6 . A dc-dc converter system as claimed in  claim 4  wherein the non-regulated mode of operation has a duty cycle of the controlled rectifiers to cause substantially uninterrupted flow of power through the dc-dc bus converter. 
     
     
         7 . A dc-dc converter system as claimed in  claim 4  wherein each controlled rectifier is turned on and off in synchronization with a voltage waveform across a primary transformer winding to provide the dc intermediate voltage output, each primary winding having a voltage waveform for the non-regulated mode of operation with a fixed duty cycle and transition times which are short relative to the on state and off state times of the controlled rectifiers. 
     
     
         8 . A dc-dc converter system as claimed in  claim 7  wherein the dc-dc bus converter further comprises a filter having an inductor that is allowed to saturate during the non-regulated mode of operation. 
     
     
         9 . A dc-dc converter system as claimed in  claim 7  wherein the dc-dc bus converter further comprises an output filter having an inductor that is allowed to saturate during the non-regulated mode of operation. 
     
     
         10 . A dc-dc converter system as claimed in  claim 4  wherein the transformer has a turns ratio of 4:1. 
     
     
         11 . A dc-dc converter system as claimed in  claim 3  wherein the non-regulated mode of operation has a fixed duty cycle. 
     
     
         12 . A dc-dc converter system as claimed in  claim 2  wherein the dc-dc bus converter comprises:
 at least one transformer with at least one primary winding and at least one secondary winding; 
 a primary winding circuit that receives the dc source voltage; and 
 a secondary winding circuit having plural controlled rectifiers with parallel uncontrolled rectifiers and an output filter having an output inductor. 
 
     
     
         13 . A dc-dc converter system as claimed in  claim 12  wherein the controlled rectifiers are driven from signals derived from the at least one secondary winding. 
     
     
         14 . A dc-dc converter system as claimed in  claim 12  wherein the non-regulated mode of operation has a duty cycle of the controlled rectifiers to cause substantially uninterrupted flow of power through the dc-dc bus converter. 
     
     
         15 . A dc-dc converter system as claimed in  claim 12  wherein each controlled rectifier is turned on and off in synchronization with a voltage waveform across a primary transformer winding to provide the dc intermediate voltage output, each primary winding having a voltage waveform for the non-regulated mode of operation with a fixed duty cycle and transition times which are short relative to the on state and off state times of the controlled rectifiers. 
     
     
         16 . A dc-dc converter system as claimed in  claim 15  wherein the dc-dc bus converter further comprises a filter having an inductor that is allowed to saturate during the non-regulated mode of operation. 
     
     
         17 . A dc-dc converter system as claimed in  claim 15  wherein the dc-dc bus converter further comprises an output filter having an inductor that is allowed to saturate during the non-regulated mode of operation. 
     
     
         18 . A dc-dc converter system as claimed in  claim 12  wherein the transformer has a turns ratio of 4:1. 
     
     
         19 . A dc-dc converter system as claimed in  claim 2  wherein the dc-dc bus converter further comprises a filter having an inductor that is allowed to saturate during the non-regulated mode of operation. 
     
     
         20 . A dc-dc converter system as claimed in  claim 2  wherein the dc-dc bus converter further comprises an output filter having an inductor that is allowed to saturate during the non-regulated mode of operation. 
     
     
         21 . A dc-dc converter system as claimed in  claim 2  wherein the non-regulated mode of operation has a fixed duty cycle.