High-voltage generator with selective half-bridge and full-bridge operation

• US 5,189,602 A
• Filed: 09/26/1991
• Issued: 02/23/1993
• Est. Priority Date: 05/12/1989
• Status: Expired due to Term

• Current Assignee: General Electric CGR SA (General Electric Company)
• Original Assignee: General Electric CGR SA (General Electric Company)
• Inventors: Callier, Bernard, Maynard, Jean-Pierre
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US07/765,488
• Time in Patent Office: 516 Days
• Field of Search: 363/17, 363/41, 363/95, 363/28, 363/37, 363/71, 378/104, 378/112
• US Class Current: 363/28
• CPC Class Codes: H02M 3/315 using semiconductor devices only
• CPC Class Codes: H05G 1/20 with high-frequency ac; with pulse trains pulse generators in general H03K3/00, H03K4/00
• CPC Class Codes: H05G 1/32 Supply voltage of the X-ray apparatus or tube

Abstract

An assembly is made enabling an inverter of a high-voltage generator to pass from a full-bridge use to a half-bridge use, in replacing a connection circuit of a mid-point of a first rectifier of this generator at a mid-point of the inverter by a circuit that is frequency controlled at the rate at which the inverter itself is controlled. By this approach, the two assemblies are made compatible and it becomes possible to pass from one assembly to the other as a function either of a high power to be supplied or of a ripple, which cannot be tolerated, of a residual voltage rectified by a second rectifier.

Claims

1. A high-voltage generator with wide range of power comprising:

a first AC-DC rectifier to rectify a low-voltage, low-frequency AC electrical signal into a low-voltage DC signal;

a full-bridge inverter controlled at high frequency to convert this low-voltage DC signal into a low-voltage, high-frequency AC signal;

a transformer to raise the voltage of this low-voltage, high-frequency AC signal;

and a second rectifier to convert a high-voltage, high frequency AC signal thus obtained into a high-voltage DC signal, comprising;

a connection circuit controlled at said high frequency AC electrical signal to connect a mid-point of the first rectifier to a mid-point of the full-bridge inverter, only when the generator is to be used at low power so as to serially connect a primary winding of said transformer between said mid-points,

means for opening said connection circuit when said generator is to be used at full-power so as to connect said primary winding of said transformer to said first AC-DC rectifier in parallel,

and means for the automatic disconnection of the connection circuit at the start of each operation pulse of the high-voltage generator.

2. A generator according to claim 1, wherein said connection circuit includes, in series in the connection, two thyristors mounted back to back and in parallel, and a control circuit to alternately trigger each of these thyristors twice in succession for successive cycles of the low-voltage, high-frequency signal to be produced.

3. A generator according to claim 2, wherein the control circuit is designed to trigger a second thyristor of this connection circuit while the first one is still on.

4. A generator according to any one of the claims 1 to 3, wherein the control circuit has means to disconnect the connection circuit when the generator is used in high-power mode.

5. A high-voltage generator with wide range of power comprising:

a first AC-DC rectifier to rectify a low-voltage, low-frequency AC electrical signal into a low-voltage DC signal;

a full-bridge inverter controlled at high frequency to convert this low-voltage DC signal into a low-voltage, high-frequency AC signal;

a transformer to raise the voltage of this low-voltage, high-frequency AC signal;

and a second rectifier to convert a high-voltage, high frequency AC signal thus obtained into a high-voltage DC signal, comprising;

means for measuring a value of the high-voltage DC signal;

a connection circuit controlled at said high frequency AC electrical signal to connect a mid-point of the first rectifier to a mid-point of the full-bridge inverter, only when the generator is to be used at low power so as to serially connect a primary winding of said transformer between said mid-points;

means for opening said connection circuit when said generator is to be used at full-power so as to connect said primary winding of said transformer to said first AC-Dc rectifier in parallel;

and means for automatic disconnection of the connection circuit when the measured high-voltage DC signal falls below a predetermined threshold.

6. A generator according to claim 5, wherein the connection circuit includes, in series in the connection, two thyristors mounted back to back and in parallel, and a control circuit to alternately trigger each of these thyristors twice in succession for successive cycles of the low-voltage, high-frequency signal to be produced.

7. A generator according to claim 6, wherein the control circuit is designed to trigger a second thyristor of this connection circuit while the first one is still on.

8. A generator according to any one of the claims 5 to 7, wherein the control circuit has means to disconnect the connection circuit when the generator is used in high-power mode.