REGULATED DC TO DC CONVERTER WITH REGULATED CURRENT SOURCE DRIVING A NONREGULATED INVERTER

• US 3,737,755 A
• Filed: 03/22/1972
• Issued: 06/05/1973
• Est. Priority Date: 03/22/1972
• Status: Expired due to Term

• Current Assignee: Billy Harold Hamilton, Edwin Theodore Calkin, Frank Carl La Porta
• Original Assignee: Billy Harold Hamilton, Edwin Theodore Calkin, Frank Carl La Porta
• Inventors: Hamilton, Billy Harold, La Porta, Frank Carl, Calkin, Edwin Theodore
• Primary Examiner(s): Shoop, Jr., William M.
• Application Number:
  US05/236,889
• Time in Patent Office: 440 Days
• Field of Search: 321/2,21,18
• US Class Current: 363/17
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current

Abstract

A regulated DC to DC converter comprises a switching-type regulated current source driving a non-regulated bridge-type inverter. The output signal of the converter is regulated by pulse width modulating the switching device in the switching regulator. The output impedance of the current source is inductive. This inductive impedance, which comprises the freewheeling or flyback inductor of the switching regulator, operates as the principal filter inductor of the converter. This regulator-inverter combination advantageously simplifies the switching control of the inverter switching devices and reduces the switching losses therein. It eliminates the switching control problems which normally occur due to switchthrough phenomena and the saturation of the inverter transformer.

Claims

1. A converter circuit comprising, an inverter circuit including at least a switching device, a regulated current source to supply signal energy to said inverter circuit, said current source including a switching regulator having an inductive output impedance and clamping means to limit the voltage output of said regulator at less than some specified voltage limit, said inductive output impedance including an inductor which serves as a sole current source path between said regulator and said inverter if the voltage output of said regulator is less than said specified voltage.

2. A converter circuit as defined in claim 1 wherein said inverter circuit includes four switching devices connected In a bridge configuration and two turnoff loss reduction networks connected to opposite bridge arm junctions, each turnoff loss reduction network comprising a series connected diode and capacitor connecting respective ones of said bridge arm junctions to said input terminals, and a resistor shunting said diode.

3. A converter circuit as defined in claim 1 wherein said inverter circuit includes four switching devices connected in a bridge configuration and two turnoff loss reduction networks connected to opposite bridge arm junctions and each including a series connected diode and capacitor, a square wave current source to drive said switching devices, and means to utilize said square wave current source to charge said capacitors including a series connected transformer, rectifier and filter to couple said square wave current source to said capacitor.

4. A converter circuit comprising a switching regulator having a switching device and an inductive output impedance including a flyback inductor, a source of voltage to drive said switching regulator, means to pulse width modulate said switching device to regulate the current output of said switching regulator, an unregulated inverter circuit having switching devices including driving means to switch said switching devices at a constant duty cycle, said inductive output impedance connected directly to the input of said inverter circuit, a series connected unidirectional conducting device and oppositely poled voltage breakdown device connecting the junction of said switching regulator and said inverter input with said source of voltage.

5. A converter circuit as defined in claim 4 wherein said inverter compirses four of said switching devices connected in a bridge configuration, and means to reduce turn off losses in the switching devices including capacitive energy storage devices, connected to the opposite junctions of opposite pairs of said switching devices.

6. A converter circuit as defined in claim 5 wherein said means to reduce turnoff losses include charging means to charge said capacitive energy storage devices including means to couple said capacitive energy storage devices to said source of voltage.

7. A converter circuit as defined in claim 5 wherein said means to reduce turnoff losses includes charging means to charge said capacitive energy storage devices including means to derive a charging current from said driving means to switch said switching devices comprising a series connected transformer, rectifier and filter coupling said driving means to said capacitive energy storage devices.

8. A converter circuit as defined in claim 5 wherein said switching devices comprise switching transistors including base emitter junctions and diodes respectively shunting each of said base emitter junctions and poled in an opposite current direction to the current direction of said base emitter junctions.

9. A converter circuit as defined in claim 5 wherein said switching regulator includes a loss reduction network including a regulator connected capacitive energy storage device, means to charge said regulator connected capacitive energy storage device including means to derive a charging current from said driving means to switch said switching devices.