Current-type GTO inverter with surge energy restoration

• US 4,567,555 A
• Filed: 07/17/1984
• Issued: 01/28/1986
• Est. Priority Date: 02/24/1984
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Meidensha (Meidensha Corporation)
• Original Assignee: Kabushiki Kaisha Meidensha (Meidensha Corporation)
• Inventors: Suzuki, Toshiaki, Hashimoto, Hitoshi, Matsuse, Kohki
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): REBSCH, DONALD
• Application Number:
  US06/631,809
• Time in Patent Office: 560 Days
• Field of Search: 318/759, 318/762, 363/35, 363/37, 363/51, 363/138, 363/137
• US Class Current: 363/138
• CPC Class Codes: H02M 5/4505 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/757 using semiconductor devices only

Abstract

In a current type GTO inverter, commutation surge voltage is inevitably generated from an inductive load whenever each GTO is turned off. The commutation surge voltage thus generated is once stored in a capacitor (C₁) through a diode surge voltage rectifier (5) and then restored to the DC source terminals (3A, 3B) of the GTO bridge-connected inverter (3) through a pair of other GTOs (G₇, G₈) turned on during steady state intervals of inverter commutation. Magnetic energy stored in a reactor (Lr₁, Lr₂) in motor-driving operation is recharged to the capacitor (C₁) through the diode surge voltage rectifier (5) after the GTOs (G₇, G₈) have been turned off; the motor kinetic energy stored in the capacitor (C₁) through diodes (D₈, D₉) in motor-braking operation is regenerated to the AC source side of the inverter (3) through a pair of other GTOs (G₉, G₁₀) when the voltage across the capacitor (C₁) exceeds a predetermined value, and magnetic energy stored in the reactor (Lr₁, Lr₂) in motor-braking operation is recharged to the capacitor (C₁) through diodes (D₁₂, D₁₃) after the GTOs (G₉, G₁₀) have been turned off. The circuit operation is stable at higher frequency range because no vibration circuits are provided, and the energy conversion efficiency is high because every energy loss is effectively restored to the inverter or the power source side.

Claims

1. In a current type gate turn-off thyristor inverter having AC source terminals for driving an induction motor, comprising:

(a) a GTO bridge-connected inverter;

(b) a thyristor bridge-connected rectifier;

(c) a diode bridge-connected commutation surge voltage rectifier connected to said GTO bridge-connected inverter;

(d) a capacitor connected to said diode bridge-connected commutation surge voltage rectifier for storing a commutation surge voltage energy generated when each of the thyristors of said GTO bridge-connected inverter is turned off;

(e) a cumulative reator having a first winding a positive side of which is connected to a positive terminal of said inverter and a second winding a negative side of which is connected to a negative terminal of said inverter;

(f) a DC reactor connected between said rectifier and said inverter;

(g) a first gate turn-off thyristor a cathode of which is connected to a negative side of the first winding of said cumulative reactor and an anode of which is connected to a positive side of said capacitor;

(h) a second gate turn-off thyristor a cathode of which is connected to a negative side of said capacitor and an anode of which is connected to a positive side of the second winding of said cumulative reactor;

(i) a first diode an anode of which is connected to the positive side of the second winding of said cumulative reactor and a cathode of which is connected to the positive side of said capacitor; and

(j) a second diode an anode of which is connected to the negative side of said capacitor and a cathode of which is connected to the negative side of the first winding,

the improvement wherein said first gate turn-off thyristor is turned on during steady state intervals of inverter commutation and off during transient state intervals of inverter commutation, and

said second gate turn-off thyristor is turned on during steady state intervals of inverter commutation and off during transient state intervals of inverter commutation,

and wherein said current type gate turn-off thyristor inverter further comprises;

(k) a third gate turn-off thyristor an anode of which is connected to the positive side of said capacitor and a cathode of which is connected to the positive side of said second winding of said reactor, said third gate turn-off thyristor being turned on while the voltage charged in said capacitor exceeds a predetermined value;

(l) a fourth gate turn-off thyristor an anode of which is connected to the negative side of said first winding of said reactor and a cathode of which is connected to the negative side of said capacitor, said fourth gate turn-off thyristor being turned on while the voltage charged in said capacitor exceeds a predetermined value;

(m) a third diode an anode of which is connected to the negative side of said first winding of said reactor and a cathode of which is connected to the positive side of said capacitor; and

(n) a fourth diode an anode of which is connected to the negative side of said capacitor and a cathode of which is connected to the positive side of said second winding of said reactor,

whereby the commutation surge voltage energy stored in said capacitor during transient state of motor-driving operation is restored to the positive and negative terminals of said inverter through said first and second gate turn-off thyristors during steady state intervals of inverter commutation, magnetic energy stored in said reactor during transient state of motor-driving operation is recharged to said capacitor through said diode bridge-connected commutation surge voltage rectifier after said first and second gate turn-off thyristors have been turned off, the motor kinetic energy generated during motor-braking operation is stored in said capacitor through said first and second diodes and regenerated to the AC source terminal of said inverter through said third and fourth gate turn-off thyristors when the voltage across said capacitor exceeds a predetermined value, and magnetic energy stored in said reactor during motor-braking operation is recharged to said capacitor through said third and fourth diodes after the said third and fourth gate turn-off thyristors have been turned off.