JP4134380B2 - Voltage / current polarity detection device and power conversion device including the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to detecting a polarity of a voltage applied between both terminals specific to a power conversion device, particularly to both ends of a bidirectional semiconductor switch, and detecting a direction of a current flowing in the bidirectional semiconductor switch.
[0002]
[Prior art]
In order to control or protect a power converter, or a semiconductor switch, in particular a bidirectional semiconductor switch, the polarity of the voltage applied between the terminals specific to the power converter, for example across the bidirectional semiconductor switch, and It is necessary to detect the current direction of the bidirectional semiconductor switch. Generally, a voltage polarity detection circuit as shown in Fig. 5 is used. In FIG. 5, 101 and 102 are light emitting diodes, and 103 and 104 are resistors. The voltage polarity between x and y is determined depending on whether the light emitting diode 101 emits light or the light emitting diode 102 emits light.
[0003]
[Problems to be solved by the invention]
However, in the voltage polarity detection circuit described above, when there is a high voltage between x and y, the resistor 104 must be high. When the resistance value of the resistor 104 is high, there is a problem that the low voltage polarity between x and y cannot be detected.
Therefore, the present invention relates to the detection of the voltage polarity and current direction between both terminals specific to the power converter, even if this voltage changes over a wide range, and whether this voltage polarity is high or low. A voltage / current polarity detection device capable of detecting the direction of current is provided. In particular, an object of the present invention is to provide a voltage / current polarity detection device capable of detecting the polarity of a voltage applied to both ends of a bidirectional semiconductor switch and the direction of a current flowing through the bidirectional semiconductor switch.
[0004]
[Means for Solving the Problems]
In order to solve the above problem, the present invention provides a voltage / current polarity detection device for detecting a voltage / current polarity between any two terminals (x) (y) in a power converter, wherein a cathode is connected to the terminal (x). A first diode (1), a second diode (2) having a cathode connected to the terminal (y), a third diode (3) having a cathode connected to the terminal (x), A fourth diode (4) having a cathode connected to the terminal (y), and a DC power source (13) having a negative electrode connected to the anodes of the first diode (1) and the second diode (2) A first resistor (5) having one end connected to the anode of the third diode (3) and the other end connected to the positive electrode of the DC power source (13); and one end connected to the fourth diode (4 ) And the other end of the first resistor (5) connected to the positive electrode of the DC power source (13) and the first resistor (5). A voltage polarity for determining the polarity of the voltage applied between the terminal (x) and the terminal (y) based on the polarity of the voltage between the terminal and the one end of the second resistor (6) And a determination unit.
Further, in claim 1, a third resistor (7) connected in parallel to the first diode (1) and a fourth resistor (8) connected in parallel to the second diode (2) ,
Is provided.
Further, in the voltage / current polarity detection device for detecting the voltage / current polarity between any two terminals (x) and (y) in the power conversion device, the first diode (1) whose anode is connected to the terminal (x) A second diode (2) having an anode connected to the terminal (y), a third diode (3) having an anode connected to the terminal (x), and an anode to the terminal (y) A fourth diode (4) connected, a DC power source (13) having a positive electrode connected to the first diode (1) and the second cathode, and one end of the third diode (3) A first resistor (5) connected to the cathode and having the other end connected to the negative electrode of the DC power supply (13), and one end connected to the fourth cathode and the other end connected to the negative electrode of the DC power supply (13) Based on the polarity of the voltage between the connected second resistor (6) and the one end of the first resistor (5) and the one end of the second resistor (6). There are, is provided with a voltage polarity determination unit which determines the polarity of the voltage applied between the terminals (x) and the terminal (y).
The current polarity between the two terminals is discriminated based on the voltage polarity output from the voltage polarity discriminating unit.
The power conversion device according to claim 1 or 3, wherein the power converter includes a semiconductor switch having one end connected to the terminal (x) and the other end connected to the terminal (y) so that current can flow bidirectionally. The polarity of the voltage applied to both ends of the semiconductor switch or the current polarity of the semiconductor switch is determined based on the voltage polarity signal output from the polarity determination unit.
A first semiconductor switch means (9) having a collector connected to the terminal (x) and an emitter connected to the negative electrode of the DC power source (13); a collector connected to the terminal (y); Second semiconductor switch means (10) connected to the negative electrode of a DC power supply (13), and the first semiconductor switch means (9), the second semiconductor switch means (10), and the first semiconductor switch means (10). The diode (1) and the second diode (2) constitute a semiconductor switch that allows current to flow in both directions.
Further, in claim 6, a third resistor (7) connected in parallel to the first diode (1), and a fourth resistor (8) connected in parallel to the first diode (2), Are provided.
Further, in claim 1, the first semiconductor switch means (9) having an emitter connected to the terminal (x) and a collector connected to the positive electrode of the DC power source (13), and an emitter connected to the terminal (y) Second semiconductor switch means (10) connected and connected to the positive electrode of the DC power source (13), the first semiconductor switch means (9) and the second semiconductor switch means (10) The first diode (1) and the second diode (2) constitute a semiconductor switch that allows current to flow bidirectionally.
Further, in claim 8, a third resistor (7) connected in parallel to the first diode (1), and a fourth resistor (8) connected in parallel to the first diode (2) Are provided.
Further, in claim 6 or 8, the DC power source (13) is shared and used as a gate drive power source for the first semiconductor switch means (9) and the second semiconductor switch means (10). is there.
The power conversion device includes the voltage / current polarity detection device according to any one of claims 1 to 10.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment of the present invention. 1, reference numeral 21 is a power converter, x and y are arbitrary terminals in the power converter 21, 1,2,3,4 are diodes, 5,6,7,8,11,12 are resistors, 15 and 16 are DC power supplies, and 14 is a comparator. In the drawings, the same names are assigned the same reference numerals, and duplicate descriptions are omitted.
The potentials at the terminals x, y, a, b, o, and p are Vx, Vy, Va, Vb, Vo, and Vp, respectively. The resistance values of the resistors 7 and 8 must be high so that the influence of the current between the Vx, Vy and x, y terminals can be ignored. The resistance values of the resistors 5 and 6 are the same, the resistance values of the resistors 7 and 8 are the same, the resistance values of the resistors 11 and 12 are the same, and the forward voltages of the diode 3 and the diode 4 are the same. The forward voltages of diodes 1, 2, 3, and 4 are VF1, VF2, VF3, and VF4, respectively.
The reverse withstand voltage of diodes 1, 2, 3, and 4 must be higher than the maximum voltage at both x and y terminals.
1. When the voltage at both the x and y terminals is higher than the voltage E of the DC power supply 13, only one of the diode 3 and the diode 4 becomes conductive. Due to the action of the resistors 7 and 8, Vo is between Vx and Vy. Due to the action of the diodes 1 and 2, Vo is almost the same as the lower one of Vx and Vy. For example, when Vx> Vy, Vx>Vo> Vy. Accordingly, the diode 2 becomes conductive, and Vo = Vy + VF2, that is, Vp = V0 + E> Vy. Therefore, the diode 4 becomes conductive and Vb = Vy + VF4. Further, since Vx> Vy + E, the diode 3 is cut off, and Va = Vp = Vy + E + VF2> Vy + Vf4 = Vb.
As with Vx <Vy, Va <Vb is obtained. Let the absolute value of V be expressed as ABS (V).
Further, even if ABS (Vx−Vy) is high, ABS (Va−Vb) is lower than (E + ε). Note that ε is ABS (VF2-VF4) or ABS (VF1-VF3).
2. When the voltage at both the x and y terminals is lower than the voltage E of the DC power supply 13, both the diode 3 and the diode 4 are turned on, and Va = Vx + VF3 and Vb = Vy + VF4. Therefore, Va-Vb = Vx-Vy + VF3-VF4 is obtained. That is, if ABS (Vx-Vy)> ABS (VF1-VF3), the signs of Va-Vb and Vx-Vy are the same. The closer the forward voltage of diode 3 and diode 4 is, the higher the accuracy of voltage polarity detection.
That is, the voltage polarity at both ends of x and y can be determined from the polarity of the voltage at both ends of a and b.
[0006]
The resistors 11 and 12, the DC power supplies 15 and 16, and the comparator 14 compare the levels of Va and Vb, and the level of Va and Vb from the voltage level of the terminal z, that is, the voltage polarity of both the x and y terminals Can be detected. The DC power supply 13 and the DC power supply 15 may be the same power supply.
[0007]
As shown in FIG. 2, there is a semiconductor switch 22 capable of flowing current bidirectionally between both terminals x and y of the power converter 21, and the current ixy (excluding leakage current) is uniform in the semiconductor switch 22. When flowing in the direction, a voltage Vxy having a certain polarity exists between the terminal x and the terminal y, and when the direction of the current ixy (excluding the leakage current) is reversed, the polarity of the voltage Vxy is also reversed. According to the present invention, the direction of the current ixy (excluding the leakage current) flowing through the semiconductor switch 22 can be detected as shown in FIG.
The semiconductor switch 22 of FIG. 2 may be a semiconductor switch as shown in FIGS. 3A, 3B, 3C, 3D, that is, the voltage polarity detection circuit shown in FIG. , (b), (c), and (d), the polarity of the voltage across the semiconductor switch and the direction of the current (excluding the leakage current) flowing through the semiconductor switch can be detected.
FIG. 3A shows a semiconductor switch composed of a semiconductor element (IGBT in this figure) and a diode connected in parallel with opposite polarity. When a current flows from x to y, it passes through the semiconductor element 31 and Vx> Vy. When current flows from y to x, it passes through the diode 32 and Vx <Vy.
FIG. 3 (b) shows a bidirectional semiconductor switch in which two semiconductor elements (GTO in this figure) capable of having a reverse breakdown voltage are connected in parallel in reverse polarity. When a current flows from x to y, it passes through the semiconductor element 33 and Vx> Vy. When a current flows from y to x, it passes through the semiconductor element 34 and Vx <Vy.
FIG. 3 (c) shows a bidirectional semiconductor switch in which two pairs of semiconductor switches composed of semiconductor elements (IGBT in this figure) and diodes connected in series with forward polarity are connected in parallel with opposite polarities. When a current flows from x to y, it passes through the diode 35 and the semiconductor element 36, and Vx> Vy. When a current flows from y to x, it passes through the diode 38 and the semiconductor element 37, and Vx <Vy.
FIG. 3 (d) shows a bidirectional semiconductor switch in which two pairs of semiconductor switches composed of semiconductor elements (IGBT in this figure) and diodes connected in parallel with opposite polarity are connected in series with opposite polarity. When a current flows from x to y, it passes through the semiconductor element 9 and the diode 40, and Vx> Vy. When a current flows from y to x, it passes through the semiconductor element 10 and the diode 39, and Vx <Vy.
The polarity of the diode 1-4 and the DC power supply 13 in FIG. 1 or 2 may be reversed. Using the leakage currents of diode 1 and diode 2 in FIG. 1 or 2 does not change the effect even if resistors 7 and 8 are not provided, but it is preferable to have them.
[0008]
According to the present invention, the voltage polarity across the bidirectional semiconductor switch as shown in FIG. 3 (d) is obtained by using the diode 39 and the diode 40 in FIG. 3 (d) in place of the diode 1 and the diode 2 in FIG. 1, respectively. Alternatively, the current direction can be detected as shown in FIG. 4 as in FIG. In the case of FIG. 4, the DC power supply 13 may be the same power supply as the DC power supply of the gate driver circuit of the semiconductor element 9 or the semiconductor element 10. The ability to share a power source in this way is important for reducing the overall size and weight of the power conversion device. For example, in a three-phase PWM cycloconverter, there are nine bidirectional semiconductor switches, and it is necessary to detect the polarity of the voltage applied to both ends of each of these and the current direction of the semiconductor switch. And the DC power supply (13) can be shared, which reduces the number of parts, and is effective in reducing the size and weight of the power conversion device and improving the reliability. If Fig. 3 (d) is applied as a bidirectional semiconductor switch, the gate driver circuit of the semiconductor element and the DC power source (13) can be shared, but Fig. 3 (a), (b) and (c) are applied. In this case, the power supply cannot be shared.
Even if the resistors 7 and 8 are not used by utilizing the leakage current of the diodes 39 and 40 in FIG. 4 or the leakage current of the semiconductor elements 9 and 10, the effect is not changed, but it is better.
[0009]
【The invention's effect】
As described above, in the present invention, by using two diodes connected in series in the opposite direction, the lower one of the potentials at both ends of the semiconductor switch is used as a reference voltage, and another two diodes are used to cut off the high voltage. There is an effect that the polarity of this voltage can be reliably detected even when the voltage applied between the two specific terminals in the power conversion device changes over a wide range or when the voltage is high or low. Therefore, it is possible to detect the polarity of the voltage across the semiconductor switch or the direction of the current (excluding the leakage current) flowing through the semiconductor switch. In particular, it is possible to provide a voltage / current polarity detection device for detecting the polarity of the voltage applied to both ends of the semiconductor switch and the current direction of the semiconductor switch in order to control the bidirectional semiconductor switch. Useful for controlling semiconductor switches.
[Brief description of the drawings]
FIG. 1 is a circuit diagram for detecting the polarity of a voltage applied between specific terminals of a power converter.
FIG. 2 is a circuit diagram for detecting the polarity and current direction of a voltage applied between both terminals of a semiconductor switch.
FIG. 3 is a configuration diagram of a semiconductor switch.
FIG. 4 is a circuit diagram for detecting the polarity and current direction of the voltage across the bidirectional semiconductor switch.
FIG. 5 is a circuit diagram for detecting the polarity of a conventional voltage.
[Explanation of symbols]
1, 2, 3, 4, 32, 35, 38, 39, 40 Diode 5, 6, 7, 8, 11, 12, 103, 104 Resistor 9, 10, 31, 36, 37 Semiconductor element IGBT
33, 36 Semiconductor device GTO capable of reverse breakdown voltage
13, 15, 16 DC power supply 14 Comparator 21 Power converter 22 Semiconductor switch 101, 102 Light emitting diodes a, b, o, p, x, y, z Potentials of terminals Va, Vb, Vo, Vp, Vx, Vy

Claims (11)

In the voltage / current polarity detection device that detects the voltage / current polarity between any two terminals (x) (y) in the power conversion device,
A first diode (1) having a cathode connected to the terminal (x);
A second diode (2) having a cathode connected to the terminal (y);
A third diode (3) having a cathode connected to the terminal (x);
A fourth diode (4) having a cathode connected to the terminal (y);
A DC power source (13) having a negative electrode connected to the anodes of the first diode (1) and the second diode (2);
A first resistor (5) having one end connected to the anode of the third diode (3) and the other end connected to the positive electrode of the DC power source (13);
A second resistor (6) having one end connected to the anode of the fourth diode (4) and the other end connected to the positive electrode of the DC power source (13);
Applied between the terminal (x) and the terminal (y) based on the polarity of the voltage between the one end of the first resistor (5) and the one end of the second resistor (6) A voltage / current polarity detection device comprising: a voltage polarity discrimination unit for discriminating the polarity of the voltage to be applied. A third resistor (7) connected in parallel to the first diode (1);
A fourth resistor (8) connected in parallel to the second diode (2);
The voltage / current polarity detection device according to claim 1, wherein: In the voltage / current polarity detection device that detects the voltage / current polarity between any two terminals (x) (y) in the power conversion device,
A first diode (1) having an anode connected to the terminal (x);
A second diode (2) having an anode connected to said terminal (y);
A third diode (3) having an anode connected to the terminal (x);
A fourth diode (4) having an anode connected to the terminal (y);
A DC power supply (13) having a positive electrode connected to the first diode (1) and the second cathode;
A first resistor (5) having one end connected to the cathode of the third diode (3) and the other end connected to the negative electrode of the DC power source (13);
A second resistor (6) having one end connected to the fourth cathode and the other end connected to the negative electrode of the DC power source (13);
Applied between the terminal (x) and the terminal (y) based on the polarity of the voltage between the one end of the first resistor (5) and the one end of the second resistor (6) A voltage / current polarity detection device comprising: a voltage polarity discrimination unit for discriminating the polarity of the voltage to be applied.   4. The voltage / current polarity detection device according to claim 1, wherein a current polarity between the two terminals is determined based on a voltage polarity output from the voltage polarity determination unit. 5. One end is connected to the terminal (x), the other end is connected to the terminal (y), and a semiconductor switch that allows current to flow bidirectionally is provided in the power converter,
4. The voltage polarity applied to both ends of the semiconductor switch or the current polarity of the semiconductor switch is determined based on a voltage polarity signal output from the voltage polarity determination unit. The voltage / current polarity detection device described. First semiconductor switch means (9) having a collector connected to the terminal (x) and an emitter connected to the negative electrode of the DC power source (13);
Second semiconductor switch means (10) having a collector connected to the terminal (y) and an emitter connected to the negative electrode of the DC power source (13);
The first semiconductor switch means (9), the second semiconductor switch means (10), the first diode (1), and the second diode (2) constitute a semiconductor switch that allows current to flow bidirectionally. The voltage / current polarity detection device according to claim 1, wherein: A third resistor (7) connected in parallel to the first diode (1);
A fourth resistor (8) connected in parallel to the first diode (2);
The voltage / current polarity detection device according to claim 6, wherein: First semiconductor switch means (9) having an emitter connected to the terminal (x) and a collector connected to the positive electrode of the DC power source (13);
Second semiconductor switch means (10) having an emitter connected to the terminal (y) and a collector connected to the positive electrode of the DC power source (13);
The first semiconductor switch means (9), the second semiconductor switch means (10), the first diode (1), and the second diode (2) constitute a semiconductor switch that allows current to flow bidirectionally. The voltage / current polarity detection device according to claim 1, wherein: A third resistor (7) connected in parallel to the first diode (1);
The voltage / current polarity detection device according to claim 8, further comprising a fourth resistor (8) connected in parallel to the first diode (2).   9. The DC power supply (13) is used as a gate drive power supply for the first semiconductor switch means (9) and the second semiconductor switch means (10) to be the same power supply. The voltage / current polarity detection device described.   The said power converter device is provided with the voltage current polarity detection apparatus in any one of Claim 1 to 10, The power converter device characterized by the above-mentioned.

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