Power converter

• US 20010028572A1
• Filed: 02/28/2001
• Published: 10/11/2001
• Est. Priority Date: 06/29/1999
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Hiyama, Kazuaki, Hussein, Khalid Hassan, Takanashi, Ken, Tametani, Fumitaka, Hatae, Shinji
• Granted Patent: US 6,351,399 B2
• Time in Patent Office: Days
• US Class Current: 363/58
• 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 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H02M 7/5387 in a bridge configuration

Abstract

To prevent malfunction or breakdown due to a surge voltage in a power converter for converting DC into AC or the like so as to supply electric power to a load, not only a control signal is transmitted via a level shift circuit which is provided correspondingly to each of switching semiconductor elements forming a main circuit and shifts a level of a reference potential at its output side so as to follow variations of a reference potential of the switching semiconductor element to the switching semiconductor element, but a DC control power source for supplying electric power to the level shift circuit and a negative pole of the switching semiconductor element are connected to each other through at least one of an inductor and a resistance.

Claims

1. A power converter comprising:

a main circuit including;

a plurality of semiconductor element rows each having a plurality of semiconductor elements connected to one another in series, said semiconductor element rows being connected, at opposite ends thereof, to one another in parallel, and at least one of the semiconductor elements in each of the semiconductor element rows being a switching semiconductor element,

a DC main power source connected between junctions of the semiconductor element rows, and

a load connected to a series junction of the semiconductor elements in each of the semiconductor element rows;

a respective level shift circuit associated with each of the switching semiconductor elements, and configured to receive a control signal at an input side thereof and to shift, relative to a reference potential at the input side, a level of a reference potential at an output side of the level shift circuit so as to follow variations of a reference potential of the respective switching semiconductor element;

a respective drive circuit configured to receive a signal from the respective level shift circuit and configured to output a drive control signal to the respective switching semiconductor element;

a DC control power source having a negative pole connected to a point of the main circuit and configured to supply electric power to the input side of each respective level shift circuit; and

at least one of a first inductor and a first resistance inserted between the point of the main circuit and the negative pole of the DC control power source,

wherein electric power supplied from the DC main power source is converted into an alternating current or an on/off current in response to an input of the drive control signal so as to be supplied to the load;

2. A power converter according to

claim 1

, further comprising:

a capacitor inserted between the negative pole of the DC control power source and a reference potential point of the output side of the respective level shift circuit.

3. A power converter according to

claim 1

, further comprising:

at least one of a second resistance and a second inductor inserted between a reference potential point of the output side of the respective level shift circuit and a negative main pole of the switching semiconductor element corresponding to the respective level shift circuit.

4. A power converter according to

claim 1

, further comprising:

a first capacitor inserted between positive and negative feeding points common with the respective drive circuit and the output side of the respective level shift circuit; and

a diode inserted between a positive pole of the DC control power source and a positive feeding point such that a cathode of the diode is connected to the capacitor.

5. A power converter according to

claim 4

, further comprising:

at least one of a second inductor and a second resistance inserted between an anode of the diode and the positive pole of the DC control power source so as to a form a series circuit with the diode; and

a second capacitor inserted between the point of the main circuit and the anode of the diode.

6. A power converter according to

claim 1

, wherein the switching semiconductor element comprises an insulated gate type transistor, and

wherein the power converter further comprises:

a gate voltage detecting circuit including a comparison voltage source configured to output a comparison voltage lower than a normal gate voltage of the transistor and higher than an abnormal gate voltage of the transistor, and including a comparator configured to compare a voltage of the insulated gate with the comparison voltage and to output an abnormality signal when the voltage of the insulated gate is lower than the comparison voltage.

7. A power converter according to

claim 6

, wherein there is a time lag between a first time point of input of the control signal to the respective drive circuit and a second time point of output of a normal signal by the gate voltage detecting circuit, and

wherein the power converter further comprises:

an abnormality signal invalidating circuit configured to output, during a predetermined period from the first time point to a third time point occurring at or after the second time point, the normal signal by invalidating the abnormality signal output by the gate voltage detecting circuit.

8. A power converter according to

claim 1

, wherein the switching semiconductor element comprises an insulated gate type transistor, and

wherein the power converter further comprises:

a capacitor inserted in parallel with the respective drive circuit of the transistor such that a negative pole of the capacitor is connected to a negative main pole of the transistor;

a first diode inserted between a junction of a positive feeding point of the respective drive circuit and the capacitor and the insulated gate such that an anode of the first diode is connected to the insulated gate; and

a second diode inserted between the insulated gate and the negative main pole such that a cathode of the second diode is connected to the insulated gate.

9. A power converter according to

claim 1

, wherein the switching semiconductor element comprises an insulated-gate transistor having a current detecting terminal provided in parallel with a negative main pole of the transistor, and

wherein the power converter further comprises:

a shunt resistance inserted between the current detecting terminal and the negative main pole of the transistor;

a DC comparison voltage source having a reference potential at the negative main pole of the transistor;

a comparator in which one of a pair of input terminals is connected to a junction of the shunt resistance and the current detecting terminal and the DC comparison voltage source is connected to the other of the input terminals, and said comparator being configured to compare a potential difference of the shunt resistance with a voltage of the DC comparison voltage source so as to output an overcurrent detecting signal of the insulated-gate transistor;

a capacitor inserted in parallel with the respective drive circuit of the insulated-gate transistor, between positive and negative feeding points of the respective drive circuit, with the negative feeding point being connected to the negative main pole of the transistor;

a first diode inserted between the positive feeding point and the insulated gate such that an anode of the first diode is connected to the insulated gate;

a second diode inserted between the insulated gate and the current detecting terminal such that a cathode of the second diode is connected to the insulated gate; and

a third diode inserted between the current detecting terminal and the negative main pole of the transistor such that a cathode of the third diode is connected to an anode of the second diode.

10. A power converter according to

claim 1

, further comprising:

a shunt resistance inserted into a respective output line connecting the main circuit and the load;

an amplifier configured to amplify a voltage drop of the shunt resistance;

a pulsing circuit configured to receive an output signal of the amplifier and to output a pulse signal subjected to pulse width modulation; and

another level shift circuit in which a reference potential at its input side is set in floating state relative to that at its output side, said another level shift circuit being configured to receive the pulse signal and to transmit the pulse signal from the input side to the output side by shifting a level of a reference potential of the pulse signal such that a load current is detected on the basis of an output signal of the another level shift circuit.

11. A power converter comprising:

a main circuit including;

a plurality of semiconductor element rows each having a plurality of semiconductor elements connected to one another in series, said semiconductor element rows being connected, at opposite ends thereof, to one another in parallel, and at least one of the semiconductor elements in each of the semiconductor element rows being a switching semiconductor element,

a DC main power source connected between junctions of the semiconductor element rows, and

a load connected to a series junction of the semiconductor elements in each of the semiconductor element rows;

a respective level shift circuit associated with each of the switching semiconductor elements, and configured to receive a control signal at an input side thereof and to shift, relative to a reference potential at the input side, a level of a reference potential at an output side of the level shift circuit so as to follow variations of a reference potential of the respective switching semiconductor element;

a respective drive circuit configured to receive a signal from the respective level shift circuit and configured to output a drive control signal to the respective switching semiconductor element;

a DC control power source having a negative pole connected to a point of the main circuit and configured to supply electric power to the input side of each respective level shift circuit; and

a first capacitor inserted between the negative pole of the DC control power source and a reference potential point of the output side of the respective level shift circuit,

wherein electric power supplied from the DC main power source is converted into an alternating current or an on/off current in response to an input of the drive control signal so as to be supplied to the load, and

wherein the respective level shift circuit comprises a transistor having a negative pole connected to a negative pole of the DC control power source and to the reference potential at the input side of the level shift circuit, a gate configured to receive the control signal, and a positive pole configured to output, by shifting a level of the reference potential of the control signal input to the gate, the control signal to the respective drive circuit.

12. A power converter according to

claim 11

, further comprising:

at least one of a resistance and an inductor inserted between the reference potential point of the output side of the respective level shift circuit and a negative main pole of the switching semiconductor element corresponding to the respective level shift circuit.

13. A power converter according to

claim 11

, further comprising:

a second capacitor inserted between positive and negative feeding points common with the respective drive circuit and the output side of the respective level shift circuit;

a diode inserted between a positive pole of the DC control power source and a positive feeding point such that a cathode of the diode is connected to the capacitor; and

at least one of an inductor and a resistance inserted between the point of the main circuit and the negative pole of the DC control power source.

14. A power converter comprising:

a main circuit including;

a plurality of semiconductor element rows each having a plurality of semiconductor elements connected to one another in series, said semiconductor element rows being connected, at opposite ends thereof, to one another in parallel, and at least one of the semiconductor elements in each of the semiconductor element rows being a switching semiconductor element,

a DC main power source connected between junctions of the semiconductor element rows, and

a load connected to a series junction of the semiconductor elements in each of the semiconductor element rows;

a respective level shift circuit associated with each of the switching semiconductor elements, and configured to receive a control signal at an input side thereof and to shift, relative to a reference potential at the input side, a level of a reference potential at an output side of the level shift circuit so as to follow variations of a reference potential of the respective switching semiconductor element;

a DC control power source having a negative pole connected to a point of the main circuit and configured to supply electric power to the input side of each respective level shift circuit; and

at least one of a second resistance and a second inductor inserted between a reference potential point of the output side of the respective level shift circuit and a negative main pole of the switching semiconductor element corresponding to the respective level shift circuit,

wherein electric power supplied from the DC main power source is converted into an alternating current or an on/off current in response to an input of the drive control signal so as to be supplied to the load.

15. A power converter comprising:

a main circuit including;

a plurality of semiconductor element rows each having a plurality of semiconductor elements connected to one another in series, said semiconductor element rows being connected, at opposite ends thereof, to one another in parallel, and at least one of the semiconductor elements in each of the semiconductor element rows being a switching semiconductor element,

a DC main power source connected between junctions of the semiconductor element rows, and

a load connected to a series junction of the semiconductor elements in each of the semiconductor element rows;

shifting means associated with each of the switching semiconductor elements and for receiving a control signal at an input side thereof and for shifting, relative to a reference potential at the input side, a level of a reference potential at an output side of the shifting means so as to follow variations of a reference potential of the respective switching semiconductor element;

driving means for receiving a signal from the respective level shift circuit and for outputting a drive control signal to the respective switching semiconductor element;

power source means having a negative pole connected to a point of the main circuit and for supplying electric power to the input side of each respective shifting means; and

at least one of a first inductor and a first resistance inserted between the point of the main circuit and the negative pole of the power source means,

wherein electric power supplied from the DC main power source is converted into an alternating current or an on/off current in response to an input of the drive control signal so as to be supplied to the load;

16. A power converter according to

claim 15

, further comprising:

a capacitor inserted between the negative pole of the power source means and a reference potential point of the output side of the respective shifting means.

17. A power converter according to

claim 15

, further comprising:

at least one of a second resistance and a second inductor inserted between a reference potential point of the output side of the respective shifting means and a negative main pole of the switching semiconductor element corresponding to the respective shifting means.

18. A power converter according to

claim 15

, further comprising:

a first capacitor inserted between positive and negative feeding points common with the respective driving means and the output side of the respective level shifting means; and

a diode inserted between a positive pole of the DC control power source and a positive feeding point such that a cathode of the diode is connected to the capacitor.

19. A power converter according to

claim 18

, further comprising:

at least one of a second inductor and a second resistance inserted between an anode of the diode and the positive pole of the power source means so as to a form a series circuit with the diode; and

a second capacitor inserted between the point of the main circuit and the anode of the diode.

20. A power converter according to

claim 15

, wherein the switching semiconductor element comprises an insulated gate type transistor, and

wherein the power converter further comprises:

a gate voltage detecting means including a means for outputting a comparison voltage lower than a normal gate voltage of the transistor and higher than an abnormal gate voltage of the transistor, and including a comparator means for comparing a voltage of the insulated gate with the comparison voltage and for outputting an abnormality signal when the voltage of the insulated gate is lower than the comparison voltage.

21. A power converter according to

claim 20

, wherein there is a time lag between a first time point of input of the control signal to the respective driving means and a second time point of output of a normal signal by the gate voltage detecting circuit, and

wherein the power converter further comprises:

an abnormality signal means for outputting, during a predetermined period from the first time point to a third time point occurring at or after the second time point, the normal signal by invalidating the abnormality signal output by the gate voltage detecting means.

22. A power converter according to

claim 15

, wherein the switching semiconductor element comprises an insulated gate type transistor, and

wherein the power converter further comprises:

a capacitor inserted in parallel with the respective driving means of the transistor such that a negative pole of the capacitor is connected to a negative main pole of the transistor;

a first diode inserted between a junction of a positive feeding point of the respective driving means and the capacitor and the insulated gate such that an anode of the first diode is connected to the insulated gate; and

a second diode inserted between the insulated gate and the negative main pole such that a cathode of the second diode is connected to the insulated gate.

23. A power converter according to

claim 15

, wherein the switching semiconductor element comprises an insulated-gate transistor having a current detecting terminal provided in parallel with a negative main pole of the transistor, and

wherein the power converter further comprises:

a shunt resistance inserted between the current detecting terminal and the negative main pole of the transistor;

a DC comparison voltage source having a reference potential at the negative main pole of the transistor;

a comparator means in which one of a pair of input terminals is connected to a junction of the shunt resistance and the current detecting terminal and the DC comparison voltage source is connected to the other of the input terminals, and said comparator means comparing a potential difference of the shunt resistance with a voltage of the DC comparison voltage source so as to output an overcurrent detecting signal of the insulated-gate transistor;

a capacitor inserted in parallel with the respective drive circuit of the insulated-gate transistor, between positive and negative feeding points of the respective drive circuit, with the negative feeding point being connected to the negative main pole of the transistor;

a first diode inserted between the positive feeding point and the insulated gate such that an anode of the first diode is connected to the insulated gate;

a second diode inserted between the insulated gate and the current detecting terminal such that a cathode of the second diode is connected to the insulated gate; and

a third diode inserted between the current detecting terminal and the negative main pole of the transistor such that a cathode of the third diode is connected to an anode of the second diode.

24. A power converter according to

claim 15

, further comprising:

a shunt resistance inserted into a respective output line connecting the main circuit and the load;

amplifier means for amplifying a voltage drop of the shunt resistance;

pulsing means for receiving an output signal of the amplifier means and for outputting a pulse signal subjected to pulse width modulation; and

another shifting means in which a reference potential at its input side is set in floating state relative to that at its output side, said another shifting means for receiving the pulse signal and for transmitting the pulse signal from the input side to the output side by shifting a level of a reference potential of the pulse signal such that a load current is detected on the basis of an output signal of the another shifting means.