Regenerative rectifier circuit

• US 4,447,868 A
• Filed: 04/05/1982
• Issued: 05/08/1984
• Est. Priority Date: 04/05/1982
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Turnbull, Fred G.
• Primary Examiner(s): Beha, Jr., William H.
• Application Number:
  US06/365,706
• Time in Patent Office: 764 Days
• Field of Search: 363/79-81, 363/83, 363/85, 363/87, 363/88, 363/89, 363/126-129, 363/163, 363/37, 318/345 B, 318/762, 318/803
• US Class Current: 363/81
• CPC Class Codes: H02M 7/219 in a bridge configuration

Abstract

A three-phase regenerative rectifier provides power flow from ac to dc using a three-phase rectifier bridge. The reversal of the input ac voltage at the input frequency commutates current in the rectifier devices. A power transistor or field-effect transistor is coupled in inverse parallel with each rectifier device to provide a path for current from the dc output of the rectifier back to the ac supply during regeneration. The rectifier devices can be phase controlled thyristors or diodes. Control means sense the three-phase voltage and switch the transistors in phase with the ac supply. Commutation of the transistors is provided by their self-contained turn-off capabilities.

Claims

1. A phase controlled three phase regenerative rectifier responsive to an external dc voltage command, for receiving input power from a three phase ac source and supplying direct current to an external load, comprising:

a phase-controlled three phase rectifier having a plurality of gate-controlled rectifying elements arranged in a bridge configuration;

a plurality of controllable switch means with self-commutating ability coupled, respectively, in inverse parallel with each rectifying element, respectively, said plurality of controllable switch means forming an inverter;

means for sensing the output voltage of said rectifier;

means for sensing the direction of current flow to the external load; and

control means responsive to the means for sensing rectifier output voltage and to the means for sensing current flow to the external load, and coupled to said plurality of gate-controlled rectifying elements and to said plurality of controllable switch means, for adjusting the phase lag of said rectifying elements and the phase lead of said controllable switch means responsive to the direction of current flow to said external load and the difference between the dc voltage command and actual dc voltage across said external load, so that when the current supplied to the load is positive the phase lag of said rectifying elements is adjusted to provide the commanded dc voltage and when said current in said load is zero or negative the phase lead of the controlled switch means provides regenerative current to the ac source.

2. A three phase regenerative phase controlled rectifier responsive to a dc voltage command, for receiving a power input from a three phase ac source and supplying direct current to a load, comprising:

three thyristors and three rectifying diodes connected, in a bridge configuration with each of said three thyristors, respectively, in the upper half of each leg, respectively, of said bridge and each of said three diodes, respectively, in the lower half of each leg, respectively;

three transistors and three blocking diodes connected to form three pairs of one transistor and one diode in series, each one of said pairs, respectively, coupled in inverse parallel with each one of said thyristors, respectively;

three additional transistors, each one of said additional transistors connected, respectively, in inverse parallel with each of said rectifying diodes in the lower half of said bridge, respectively;

a freewheeling diode connected across the dc output of the bridge;

means for determining the direction of current flow to said load; and

control means coupled to each of said transistors and thyristors and to said means for determining direction of current flow, for adjusting the phase lag of said thyristors and the phase lead of said transistors responsive to the direction of current flow to the load and the commanded dc value.

3. The three phase regenerative phase controlled rectifier of claim 2 wherein said control means comprises:

a phase detector;

a low pass filter coupled to the output of the phase detector;

a summing amplifier receiving at one input the output voltage of said low pass filter and at another input the voltage difference between said actual and commanded dc voltages; and

a voltage controlled oscillator responsive to the output voltage of the summing amplifier and providing lagging and leading frequencies relative to the zero crossings of each phase of the line-to-line ac supply for controlling said thyristors and transistors;

said phase detector comparing the phase-shifted output frequency of the voltage controlled oscillator and a synchronizing frequency signal representative of zero crossings of each phase of the line-to-line ac supply.