Apparatus and method for turning off BJT used as controlled rectifier

• US 6,597,592 B2
• Filed: 10/03/2001
• Issued: 07/22/2003
• Est. Priority Date: 10/03/2001
• Status: Expired due to Fees

• Current Assignee: Bruce W. Carsten
• Original Assignee: Bruce W. Carsten
• Inventors: Carsten, Bruce W.
• Primary Examiner(s): Patel, Rajnikant B.
• Application Number:
  US09/971,048
• Publication Number:
  US 20030063483A1
• Time in Patent Office: 657 Days
• Field of Search: 363/127, 363/89, 363/97, 363/98, 363/17, 363/16, 323/282, 323/283, 323/284, 323/285, 323/286, 323/272, 323/278, 361/84, 361/91, 361/92, 361/93, 361/94
• US Class Current: 363/127
• 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: H02M 3/33592 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
• CPC Class Codes: H03K 17/04126 in bipolar transistor switches
• CPC Class Codes: H03K 17/0414 Anti-saturation measures
• CPC Class Codes: H03K 17/0422 Anti-saturation measures
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A controlled rectifier circuit having a BJT implemented as the controlled rectifier (CR) and first and second turn-off transistors coupled respectively between the base and collector and base and emitter of the CR BJT to rapidly remove stored charge from the collector-base junction of that CR BJT. The turn-off transistors may be implemented with BJTs, FETs (or related active electronic devices) and the polarity of the transistors may be the same or opposite to that of the CR BJT. Anti-saturation and drive current amplifying circuitry may be provided. A turn-off drive command may be delivered to an appropriate transistor via steering logic or an auto-steering configuration. The circuit is preferably implemented as an integrated circuit.

Claims

1. A controlled rectifier circuit, comprising:

a bipolar junction transistor (BJT) configured for use as a controlled rectifier (CR) and having collector, base and emitter electrodes, said base electrode being adapted to receive a turn-on drive command for turning on said CR BJT;

a first turn-off transistor having a first electrode coupled to the base electrode, a third electrode coupled to the collector electrode, and a second electrode adapted to receive a CR BJT turn-off drive command; and

a second turn-off transistor having a first electrode coupled to the base electrode, a third electrode coupled to the emitter electrode, and a second electrode adapted to receive a CR BJT turn-off drive command;

wherein each of said turn-off transistors is configured such that in the absence of a turn-on drive command at said CR BJT and the presence of a turn-off drive command at the respective one of said turn-off transistors to conduct stored charge out of the collector-base junction of said CR BJT.

2. The circuit of claim 1, wherein at least one of said first and second turn-off transistors is a BJT of the same polarity as the CR BJT, and the first, second and third electrodes of that turn-off transistor are the collector, base and emitter electrodes, respectively.

3. The circuit of claim 1, wherein at least one of said first and second turn-off transistors is a BJT of the opposite polarity as the CR BJT, and the first, second and third electrodes of that turn-off transistor are the emitter, base and collector electrodes, respectively.

4. The circuit of claim 1, wherein at least one of said first and second turn-off transistors is a field effect transistor (FET) of the same polarity as the CR BJT, and the first, second and third electrodes of that turn-off transistor are the drain, gate and source electrodes, respectively.

5. The circuit of claim 1, wherein at least one of said first and second turn-off transistors is a field effect transistor (FET) of the opposite polarity as the CR BJT, and the first, second and third electrodes of that turn-off transistor are the source, gate and drain electrodes, respectively.

6. The circuit of claim 1, wherein at least one of said first and second turn-off transistors is a BJT having collector, base and emitter electrodes, and said circuit further comprises anti-saturation circuitry associated with this BJT turn-off transistor to prevent that transistor from being driven into deep saturation by a CR BJT turn-off drive command that is delivered to the base electrode of that BJT turn-off transistor.

7. The circuit of claim 6, wherein said anti-saturation circuitry includes a diode, coupled between the collector and base electrodes of the BJT turn-off transistor, that conducts to prevent deep saturation of that transistor.

8. The circuit of claim 6, wherein said anti-saturation circuitry includes an anti-saturation transistor, coupled between the collector and base electrodes of the BJT turn-off transistor, that conducts to prevent deep saturation of the BJT turn-off transistor.

9. The circuit of claim 6, wherein said anti-saturation circuitry includes a resistor coupled between an input of a CR BJT turn-off drive command and the base electrode of said BJT turn-off transistor.

10. The circuit of claim 1, further comprising:

a turn-off drive command input; and

a circuit coupled between said turn-off drive command input and the second electrode of at least one of said first and second turn-off transistors that increases the turn-off drive command current available at said second electrode over a corresponding drive command current at said input.

11. The circuit of claim 10, further comprising anti-saturation circuitry associated with at least one of said first and second turn-off transistors for preventing that transistor from being driven into deep saturation.

12. The circuit of claim 11, wherein said anti-saturation circuitry is configured such that a turn-off drive command for the associated transistor is of sufficiently short duration so as to not drive that transistor into deep saturation.

13. The circuit of claim 10, further comprising circuitry that diverts current away from the second electrode of said one of said first and second turn-off transistor to decrease the turn-off drive command to that transistor when the CR BJT is off.

14. The circuit of claim 1, wherein the first and second turn-off transistors are BJTs of the same polarity as the CR BJT, and wherein the second electrodes of said first and second turn-off transistors are coupled such that a turn-off drive command delivered to the second electrodes is automatically routed through an appropriate one of said transistors based on the polarity of the collector-emitter voltage of said CR BJT.

15. The circuit of claim 1, further comprising a comparator having inputs coupled to the collector and emitter electrodes of said CR BJT, said comparator steering a turn-off drive command to the appropriate one of said turn-off transistors based on the polarity of the collector-emitter voltage of said CR BJT.

16. The circuit of claim 15, further comprising logic gates that function in cooperation with said comparator to achieve said steering.

17. A controlled rectifier circuit, comprising:

a bipolar junction transistor (BJT) configured for use as a controlled rectifier (CR) and having collector, base and emitter electrodes, said base electrode being adapted to receive a turn-on drive command for turning on said CR BJT;

a first turn-off transistor having a first electrode coupled to the base of the CR BJT, a third electrode coupled to the collector of the CR BJT, and a second electrode adapted to receive a CR BJT turn-off drive command, said first turn-off transistor being configured to rapidly remove stored charge from the base-collector junction of the CR BJT when the collector-emitter voltage of the CR BJT is of a negative polarity; and

a second turn-off transistor having a first electrode coupled to the base of the CR BJT, a third electrode coupled to the emitter of the CR BJT, and a second electrode adapted to receive a CR BJT turn-off drive command, said second turn-off transistor being configured to rapidly removed stored charge from the base-collector junction of the CR BJT when the collector-emitter voltage of the CR BJT is of a positive polarity.

18. The circuit of claim 17, wherein at least one of said first and second turn-off transistors is from the group of transistors including:

a BJT of the same polarity as the CR BJT;

a BJT of opposite polarity to that of the CR BJT;

a FET of the same polarity as the CR BJT; and

a FET of opposite polarity to that of the CR BJT.

19. The circuit of claim 17, wherein at least one of said first and second turn-off transistors is a BJT having collector, base and emitter electrodes, and said circuit further comprises anti-saturation circuitry associated with this BJT turn-off transistor to prevent that transistor from being driven into deep saturation by a CR BJT turn-off drive command that is delivered to the base electrode of that BJT turn-off transistor.

20. The circuit of claim 17, wherein the second electrodes of said first and second turn-off transistors are coupled such that a turn-off drive command delivered to the second electrodes is automatically routed through an appropriate one of said transistors based on the polarity of the collector-emitter voltage of said CR BJT.

21. A controlled rectifier circuit, comprising:

a bipolar junction transistor (BJT) configured for use as a controlled rectifier (CR) and having collector, base and emitter electrodes, said base electrode being adapted to receive a turn-on drive command for turning on said CR BJT;

a first active electronic device coupled between the collector and base electrodes of the CR BJT and configured to rapidly removed stored charge from the collector-base junction of the CR BJT; and

a second active electronic device coupled between the base and emitter electrodes of the CR BJT and configured to rapidly remove stored charge from the collector-base junction of the CR BJT.

22. The circuit of claim 21, wherein at least one of said first and second active electronic devices is from the group of active electronic devices including:

a BJT of the same polarity as the CR BJT;

a BJT of opposite polarity to that of the CR BJT;

a FET of the same polarity as the CR BJT; and

a FET of opposite polarity to that of the CR BJT.

23. The circuit of claim 21, wherein at least one of said first and second active electronic devices is a BJT having collector, base and emitter electrodes, and said circuit further comprises anti-saturation circuitry associated with this BJT turn-off transistor to prevent that transistor from being driven into deep saturation by a CR BJT turn-off drive command that is delivered to the base electrode of that BJT turn-off transistor.

24. The circuit of claim 21, further comprising:

a turn-off drive command input; and

a circuit coupled between said turn-off drive command input and the second electrode of at least one of said first and second active electronic devices that increases the turn-off drive command current available at said second electrode over a corresponding drive command current at said input.

25. A controlled rectifier circuit, comprising:

a bipolar junction transistor (BJT) configured for use as a controlled rectifier (CR) and having collector, base and emitter electrodes, said base electrode being adapted to receive a turn-on drive command for turning on said CR BJT;

a first turn-off transistor having first, second and third electrodes that is coupled to said CR BJT between the base and collector of said CR BJT, the first electrode being coupled to the base of the CR BJT, the third electrode being coupled to the collector of the CR BJT and the second electrode being adapted to receive a CR BJT turn-off drive command; and

a second turn-off transistor having first, second and third electrodes that is coupled to said CR BJT between the base and emitter of said CR BJT, the first electrode being coupled to the base of the CR BJT, the third electrode being coupled to the emitter of the CR BJT and the second electrode being adapted to receive a CR BJT turn-off drive command;

wherein said first turn-off transistor is configured such that in the absence of a turn-on drive command at the base of the CR BJT, the presence of a turn-off drive command at the second electrode of the first turn-off transistor and when the collector-emitter voltage of the CR BJT is of reverse polarity to conduct stored charge out of the collector base junction of the CR BJT to thereby rapidly turn-off the CR BJT; and

further wherein said second turn-off transistor is configured such that in the absence of a turn-on drive command at the base of the CR BJT, the presence of a turn-off drive command at the second electrode of the second turn-off transistor and when the collector-emitter voltage of the CR BJT is of forward polarity to conduct stored charge out of the collector base junction of the CR BJT to thereby rapidly turn-off the CR BJT.