Circuit for energizing and controlling a synchronous rotary machine operating at variable speed

• US 4,536,692 A
• Filed: 06/21/1984
• Issued: 08/20/1985
• Est. Priority Date: 02/22/1983
• Status: Expired due to Term

• Current Assignee: Societe Anonyme DBA
• Original Assignee: Cgee Alsthom
• Inventors: Godfroid, Henri
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US06/622,400
• Time in Patent Office: 425 Days
• Field of Search: 318/723, 318/803, 318/807-811, 363/71, 363/72, 363/43, 307/82
• US Class Current: 318/723
• CPC Class Codes: H02M 7/757 using semiconductor devices only
• CPC Class Codes: H02P 2201/13 DC-link of current link type, e.g. typically for thyristor bridges, having an inductor in series with rectifier
• CPC Class Codes: H02P 25/024 controlled by supply frequency

Abstract

A circuit for energizing and controlling a synchronous rotary machine which operates at variable speed and is fed by controlled static switches, wherein the stator of the rotating machine has a plurality n of polyphase windings where n is at least equal to two, each polyphase winding being fed by a static AC-AC converter (A, B) which constitutes an autosychronous inverter having a mains bridge (PRA, PRB) and a machine bridge (PMA, PMB) connected to each other by first and second DC conductors, and wherein the circuit has means for controlling the mains bridge of each converter in such a way that the sum of the DC currents (IA+IB) in said conductors of all the converters is proportional to a reference average current value.

Claims

1. A circuit for energizing and controlling a synchronous rotary machine which operates at variable speed, said machine having a stator with a plurality of n polyphase windings wherein n is at least equal to two, said circuit comprising:

a polyphase AC source of n phases corresponding in number of the n polyphase windings of said machine,

controlled static switches comprising a static AC-AC converter for feeding each polyphase winding, each said converter constituting an autosynchronous inverter comprising a polyphase mains bridge and a polyphase machine bridge connected to each other by first and second DC conductors forming a continuous current loop such that one of said bridges operates as a rectifier and the other bridge operates as an inverter, each of said bridges having n parallel paths with paired thyristors within each of said parallel paths,

and wherein said polyphase AC source is connected to said polyphase mains bridge at points between said paired thyristors for respective phases, and said n polyphase windings of said machine stator are connected to respective paths of said polyphase machine bridge at points between said paired thyristors for respective phases thereof,

and wherein the circuit includes monitoring means for monitoring the sum of the currents flowing in each loop, and control means for controlling the mains bridge of each converter such that the sum of the DC currents in said conductors of all the converters is proportional to a reference average current value.

2. A circuit according to claim 1, wherein said control means includes a speed regulator for supplying a reference average current value, a comparator circuit for comparing said average current value with said sum of the DC currents, means for applying the output of said comparator to an summing circuits, each of which feeds a respective pulse control circuit of one of the n mains bridges, and means for supplying to each summing circuit a full inverter firing signal and the output from a current regulator circuit for the corresponding one of the n converters.

3. A circuit according to claim 2, wherein the stator of the rotating machine has two three-phase windings at 30°

to each other.

4. A circuit according to claim 1, wherein said control means includes means for controlling each mains bridge to provide a substantially constant DC current in each loop independently of the rotational position of said rotatory machine, with the current in each loop exhibiting a transient decrease during switching of thyristors in the respective mains bridge, said control means responding to a detected decrease in the current in one of said loops for increasing the current in at least one remaining loop to maintain said sum of DC currents proportional to said reference average current value.

5. A circuit according to claim 2, wherein said control means includes switch means for disabling the current regulator circuit coupled to any given summing circuit while a full inverter firing signal is being supplied to said given summing circuit and for again enabling the disabled current regulator circuit when said full inverter firing signal is no longer supplied to said given summing circuit, whereby the level of the output signal provided by said current regulator circuit immediately prior to its disabling and immediately after its again enabling will be substantially uneffected by the loop current during application of said full inverter firing signal to said given summing circuit.