Semiconductor power converting apparatus

• US 6,380,796 B2
• Filed: 04/20/2001
• Issued: 04/30/2002
• Est. Priority Date: 11/05/1999
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagasu, Masahiro, Sakai, Hiromitsu, Katoh, Shuji, Iyotani, Ryuji, Aizawa, Hidetoshi
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/838,470
• Publication Number:
  US 20010015670A1
• Time in Patent Office: 375 Days
• Field of Search: 327/427, 327/430, 327/431, 327/434, 327/435
• US Class Current: 327/434
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H03K 17/166 Soft switching
• CPC Class Codes: H03K 17/168 in composite switches
• CPC Class Codes: H03K 4/00 Generating pulses having essentially a finite slope or stepped portions

Abstract

A semiconductor power converting apparatus includes a semiconductor element for controlling a current flowing between a collector and an emitter in response to a gate condition, a driving device connected to the gate, for driving the gate in response to a drive signal entered thereinto, a voltage applying device for applying both a forward bias and a reverse bias to the gate so as to set the emitter of the semiconductor element to a neutral potential, and a voltage dividing device for dividing a voltage appearing between the collector and the emitter of the semiconductor element, in which the drive signal is under OFF state, a voltage produced based upon the divided voltage by the voltage dividing device is applied to the gate, and the gate voltage is controlled in response to the voltage appearing between the collector and the emitter of the semiconductor element, thereby reducing the snubbed loss.

Claims

1. A semiconductor power converting apparatus comprising:

an insulated-gate transistor for controlling a current flowing through a collector and an emitter in response to a gate condition;

a driving circuit connected to said gate inputting a drive signal;

voltage applying means for applying both a forward bias and a reverse bias to the gate as set the emitter of said insulated-gate transistor to a neutral potential;

voltage dividing means for dividing a voltage appearing between the collector of said insulated-gate transistor and the emitter thereof, or a voltage appearing between the collector of said insulated-gate transistor and a minus-sided electrode of said voltage source by employing resistors, in which when said drive signal is an OFF command, a gate voltage of said insulated-gate transistor is brought into such a voltage condition corresponding to the voltage division; and

switching means for switching the gate voltage in such a manner that said gate voltage is equal to a negative voltage corresponding to the source voltage of said voltage source when the divided voltage detected by said voltage dividing means is lower than, or equal to a set voltage, and also said gate voltage is equal to a voltage value produced based upon the divided voltage when the divided voltage by said voltage means is higher than, or equal to the set voltage.

2. A semiconductor power converting apparatus as claimed in claim 1 wherein:

while said voltage dividing means employs either zener diode or a voltage source in order that a voltage changing ratio of the gate signal to the collector potential of the insulated-gate transistor, said voltage dividing means can suppress a peak voltage appearing between the collector and the emitter based upon a gate voltage in response to the voltage between the collector and the emitter in such a case that the voltage between the collector and the emitter of said insulated-gate transistor is higher than, or equal to a predetermined voltage.

3. A semiconductor power converting apparatus as claimed in claim 1 wherein:

said voltage dividing means changes a voltage dividing ratio in such a manner that a relationship between the gate voltage and the collector potential can be continuously, or stepwise changed, and rising of the collector potential is commenced; and

said voltage dividing means can suppress a peak voltage appearing between the collector and the emitter based upon a gate voltage in response to the voltage between the collector and the emitter in such a case that the voltage between the collector and the emitter of said insulated-gate transistor is higher than, or equal to a predetermined voltage.

4. A semiconductor power converting apparatus as claimed in claim 1 wherein:

said voltage dividing means reverse-biases a gate signal by times means for changing the voltage dividing ratio for a predetermined time period after the drive signal is switched On to OFF.

5. A semiconductor power converting apparatus as claimed in claim 1 wherein:

more than 2 sets of said semiconductor elements are connected in series to each other so as to constitute an arm;

said voltage dividing means owned by each of said insulated-gate transistors sets the voltage dividing ratio to such a voltage value obtained by dividing a voltage applied to the arm by a total number of said series-connected insulated-gate transistors of the arm; and

when a voltage appearing between the collector and the emitter of each of said insulated-gate transistors is higher than, or equal to a predetermined voltage, the gate voltage of said insulated-gate transistor is made a voltage state corresponding to the divided voltage.