JP3265410B2 - Power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter,
In particular, a power converter that converts AC power from the AC system into DC power, or DC power from the DC system into AC power, and a harmonic current flowing out of the power converter into the AC system,
Or about the power conversion equipment having a harmonic filter for suppressing harmonic voltage to be applied to the AC system.

[0002]

2. Description of the Related Art In a power converter such as an uninterruptible power supply, as a method of suppressing a harmonic current of an AC power supply system and improving a power factor, a method disclosed by Fuji Timely Vol. 63, No. 6 (1990) There is a method using a high power factor converter as described in PP399 to 405, which is provided with a harmonic filter composed of a reactor and a capacitor on the AC input side of the PWM rectifier. This constituted a high power factor converter.

[0003]

In a power converter such as the above-described uninterruptible power supply, a harmonic current which increases when a failure such as a capacitor circuit being opened in a harmonic filter or a power converter occurs. As a result, there is a problem that a harmonic failure may occur on the AC power supply side, for example, a harmonic current may flow into the phase advance capacitor and the capacitor may be heated.

The present invention has been made in view of such circumstances, and when a harmonic filter provided between a power converter and an AC system fails, excessive harmonic current flows into the AC system. an object or, to provide a power conversion equipment that can prevent harmonic disorders by excessive harmonic voltage is applied to the AC system.

[0005]

[0006]

Power converter of the present invention SUMMARY OF THE INVENTION may, AC power from the AC system to DC power, or a power converter for converting DC power from the DC system to the AC power, said power converter A power converter having a harmonic filter including a reactor and a capacitor provided on the AC side of the power converter to suppress a harmonic current flowing out to the AC system or a harmonic voltage applied to the AC system. , Characterized by comprising a failure detecting means for detecting a failure of the harmonic filter, and a power converter operation stopping means for stopping the operation of the power converter in response to a detection signal of the failure detecting means.

[0007]

In the above power converter, the failure detecting means includes a current detector for detecting a capacitor current flowing through a capacitor constituting the harmonic filter, and a rectifier for converting a detection signal of the current detector into a DC signal. And a signal level determination circuit for determining a level of an output signal of the rectifier circuit, wherein the operation of the power converter is stopped based on a determination result of the signal level determination circuit.

In the above power converter, the failure detecting means includes a harmonic detection circuit for detecting a harmonic voltage generated based on a flow of the harmonic current to the AC system, and an output of the harmonic detection circuit. A rectifying circuit that converts the signal into a DC signal; and a signal level determining circuit that determines a level of an output signal of the rectifying circuit. The operation of the power converter is stopped based on a determination result of the signal level determining circuit. It is characterized by making it. Alternatively, the failure detecting means may include the harmonic
Resistor and capacitor connected in parallel with filter capacitor
A harmonic detection circuit comprising a series circuit of
An inverter for converting the voltage between both ends of the resistor of the knowledge circuit into a DC signal.
And a signal for determining the level of the output signal of the rectifier circuit.
And a signal level determination circuit.
The operation of the power converter is stopped based on the fixed result.
Can be done.

[0010] The power converter operation stopping means may include:
It is characterized in that it comprises a logic circuit which takes a logical product of a judgment output of the signal level judgment circuit and a pulse output of a gate pulse generation circuit for generating a gate pulse to be supplied to a power converter.

[0011]

The method of operating a power converter according to the present invention, detects a failure of the harmonic filter, when a failure of the harmonic filter is detected to stop the operation of the power converter.

[0012] In the power conversion device according to the invention, when the failure of the harmonic faction filter by the failure detection means is detected, the operation stop of the power converter in response to the detection signal of the fault detection means by the power converter operation stopping means Let me do.

[0013] Thus, it is possible to prevent the application of the AC system of excessive runoff into the AC system of the harmonic current or excessive harmonic voltage, the operation of the power converter at the time of failure of the harmonic filter is stopped, Therefore, harmonic interference can be prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an entire configuration in a case where the present invention is applied to an uninterruptible power supply, which is one of the power converters. In FIG. 1, the main circuit of the uninterruptible power supply includes an AC reactor 1, an AC reactor 2, a capacitor 3 and an AC /
DC power is obtained through the DC converter 5 and AC power 1
In the event of a power failure, the DC / AC converter 7 is driven using the storage battery 6 as a DC power source, and AC power is supplied to the load 10 via the AC reactor 8 and the capacitor 9.

In FIG. 1, the fault detecting means includes a current detector 11 for detecting a current flowing to the AC system side, a filter 12, a rectifier circuit 13, a harmonic detection level setting circuit 14, a comparator 15, The power converter operation stopping means includes a gate pulse generation circuit 16 and an AND circuit 17.
And a gate drive circuit 18.

In the above configuration, when the input current of the uninterruptible power supply is detected by the current detector 11, its harmonic component is extracted by the filter 12. This harmonic component is rectified by the rectifier circuit 13, and the DC signal Vd and the harmonic detection level Vf 1 set by the harmonic detection level setting circuit 14 are compared in magnitude by the comparator 15, and are determined.
When ≧ Vf1, the harmonic detection signal K1 is set to a low level (hereinafter, referred to as L), the AND circuit 17 is turned off, and the gate pulse signal G of the gate pulse generation circuit 16 is turned off.
Stop output of

When Vd <Vf1, the harmonic detection signal K1 is set to a high level (hereinafter, referred to as H), the AND circuit 17 is turned on, and the gate pulse generation circuit 16 is turned on.
Is output.

Further, the gate drive circuit 18 amplifies the gate pulse signal G and supplies it to the AC / DC converter 5,
/ DC converter 5 is driven.

According to this embodiment, the harmonic current generated when the capacitor 3 or the AC / DC converter 5 constituting the harmonic filter fails is detected, and the operation of the power converter is performed based on the detected output. Is stopped, excessive harmonic current can be prevented from flowing out to the AC system, or excessive harmonic voltage can be prevented from being applied to the AC system.

FIG. 2 shows the configuration of another embodiment of the uninterruptible power supply to which the present invention is applied. This embodiment is different from the embodiment shown in FIG. 1 in that the detection point of the current detector 11 is on the capacitor 3 side of the harmonic filter and the capacitor circuit including the capacitor 3 is open. The determination level Vf1 of the harmonic component for determining the state;
A determination level Vf2 of a harmonic component for performing a state determination when the / DC converter 5 has failed or the capacitor 3 has deteriorated is set, and these set levels are compared with the level of the detected harmonic component. That is, the failure detection is performed by the determination. The other configuration is exactly the same as the configuration shown in FIG.

Note that the set value Vf1 is based on the point that the current flowing through the current detector 11 becomes smaller than the value flowing in the steady state when the capacitor circuit including the capacitor 3 is opened, The set value Vf2 is selected as the lower limit of the level, and the set value Vf2 is the current level flowing in the steady state because the harmonic current flowing to the current detector 11 increases when the AC / DC converter 5 fails or the capacitor 3 deteriorates. Has been selected as the upper limit.

In the above construction, the capacitor current flowing through the capacitor 3 is detected by the current detector 11, and the DC signal Vd obtained by the rectifier circuit 13 and the harmonic detection levels Vf1, Vf2 of the harmonic detection level setting circuits 14, 19 are obtained. Are compared and determined by the comparators 15 and 20.

During the operation of the AC / DC converter 5, Vd ≦ V
When f1, the harmonic detection signal K1 is set to L through the signal inversion circuit 21, the AND circuit 22, and the signal inversion circuit 23,
When Vd> Vf1, the signal inversion circuit 21 and the AND circuit 2
2. The harmonic detection signal K1 is at H level through the signal inversion circuit 23.
It is said.

When Vd ≧ Vf2, the harmonic detection signal K2 is set to L, and when Vd <Vf2, the harmonic detection signal K2 is set to H. Therefore, Vd ≦ Vf1 or Vd
When ≧ Vf2, the AND circuit 24 is turned off, the output of the gate pulse signal G from the gate pulse generation circuit 16 is stopped, and when Vf1 <Vd <Vf2,
That is, when the capacitor 3 or the AC / DC converter 5 constituting the harmonic filter is operating normally, the AND circuit 24 is turned on, and the gate pulse generation circuit 16 is turned on.
Output the gate pulse signal G.

In this embodiment, the same effects as in the embodiment shown in FIG. 1 can be obtained.

Next, the configuration of another embodiment of the uninterruptible power supply to which the present invention is applied is shown in FIG. This embodiment differs from the embodiment shown in FIG. 1 in that the change of the harmonic component included in the input current of the uninterruptible power supply is indirectly obtained by the change of the input voltage. In FIG. 3, a harmonic detection circuit 25 including a series circuit including a capacitor and a resistor is connected in parallel with the capacitor 3 so that when the capacitor 3 or the AC / DC converter 5 constituting the harmonic filter fails. When the generated harmonic current flows into the harmonic detection circuit 25, the voltage value detected by the harmonic detection circuit 25 increases, and the rectification circuit 13
Becomes Vd ≧ Vf1, the harmonic detection signal K1 is set to L, the AND circuit 17 is turned off, and the output of the gate pulse signal G from the gate pulse generation circuit 16 is stopped. .

In this embodiment, the same effects as in the embodiment shown in FIG. 1 can be obtained.

FIG. 4 shows the configuration of another embodiment of the uninterruptible power supply to which the present invention is applied. This embodiment is different from the embodiment shown in FIG. 1 in that the detection point of the current detector 11 is changed to the output current instead of the input current of the uninterruptible power supply, and the capacitor or the capacitor constituting the harmonic filter is changed. The point is that the DC / AC converter 7, which is the power converter on the output side of the uninterruptible power supply, is stopped when the power converter fails. The rest of the configuration is exactly the same as that of the embodiment shown in FIG.

According to the present embodiment, the harmonic current generated when the capacitor 9 or the DC / AC converter 7 constituting the harmonic filter fails is detected, and the operation of the power converter is stopped, whereby excessive harmonics are generated. It is possible to prevent the wave current from flowing out to the load system or to apply an excessive harmonic voltage to the load system.

Next, FIG. 5 shows a modification of the embodiment shown in FIG. This embodiment differs from the embodiment shown in FIG. 4 in that the detection point of the current detector 11 is changed to the capacitor current flowing through the capacitor 9 in place of the output current of the uninterruptible power supply. The determination of the level of the harmonic component is performed in the same manner as in the embodiment shown in FIG.
The point is that the determination is made in comparison with f2.

In this embodiment, the same effects as in the embodiment shown in FIG. 4 can be obtained.

Next, another modification of the embodiment shown in FIG. 4 is shown in FIG. This embodiment differs from the embodiment shown in FIG. 4 in that the change of the harmonic component included in the output current of the uninterruptible power supply is indirectly obtained by the change of the output voltage.

In this embodiment, the same effects as in the embodiment shown in FIG. 4 can be obtained.

Next, an application example of the present invention is shown in FIG. In the present embodiment, the DC / AC converter 7 is driven by the DC power of a DC power source 27 such as a solar cell and a fuel cell, and the AC power is supplied to the
This is an application of the embodiment shown in FIG. 4 to a power converter for supplying to a commercial AC power system including the above.

According to the present embodiment, the harmonic current generated when the capacitor 9 or the DC / AC converter 7 constituting the harmonic filter is out of order is detected, and the operation of the power converter is stopped. It is possible to prevent the wave current from flowing out to the commercial AC power system or applying an excessive harmonic voltage to the commercial AC power system.

Next, FIG. 8 shows a modification of the embodiment shown in FIG. This embodiment is different from the embodiment shown in FIG. 7 in that the detection point of the current detector 11 is changed to the capacitor current flowing through the capacitor 9 instead of the output current of the DC / AC converter 7. The determination of the level of the detected harmonic component is performed in the same manner as in the embodiment shown in FIG.
1 is that the determination is made in comparison with Vf2.

In this embodiment, the same effects as in the embodiment shown in FIG. 7 can be obtained.

FIG. 9 shows another modification of the embodiment shown in FIG. This embodiment differs from the embodiment shown in FIG. 7 in that the change of the harmonic component included in the output current of the DC / AC converter 7 is obtained indirectly by the change of the output voltage. is there.

In this embodiment, the same effects as those of the embodiment shown in FIG. 7 can be obtained.

[0040]

According to the present invention as described above,
Since the time of failure of the harmonic filter and configured to stop the operation of the power converter, prevent the application of the AC system of excessive runoff into the AC system of the harmonic current, or excessive harmonic voltage, it Therefore, it is possible to prevent the occurrence of the harmonic interference.

[Brief description of the drawings]

FIG. 1 is a circuit showing a configuration of an embodiment of an uninterruptible power supply to which the present invention is applied.

FIG. 2 is a circuit diagram showing a configuration of another embodiment of the uninterruptible power supply to which the present invention is applied.

FIG. 3 is a circuit diagram showing a configuration of another embodiment of the uninterruptible power supply to which the present invention is applied.

FIG. 4 is a circuit diagram showing a modification of the embodiment shown in FIG.

FIG. 5 is a circuit diagram showing a modification of the embodiment shown in FIG.

FIG. 6 is a circuit diagram showing another modification of the embodiment shown in FIG. 4;

FIG. 7 is a circuit diagram showing an application example of the present invention.

8 is a circuit diagram showing a modification of the embodiment shown in FIG.

FIG. 9 is a circuit diagram showing another modified example of the embodiment shown in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Reactor 4 Reactor 8 Reactor 3 Capacitor 9 Capacitor 5 AC / DC converter 6 Storage battery 7 DC / AC converter 10 Load 11 Current detector 12 Filter 13 Rectifier circuit 14 Harmonic detection level setting circuit 19 Harmonic detection level Setting circuit 15 Comparator 16 Gate pulse generation circuit 17 Logical product circuit 22 Logical product circuit 24 Logical product circuit 18 Gate drive circuit 21 Signal inversion circuit 23 Signal inversion circuit 25 Harmonic detection circuit 26 AC power generation equipment 27 DC power source

──────────────────────────────────────────────────続 き Continuing on the front page (72) Tomoaki Mino, Inventor 3-1-1, Sachimachi, Hitachi, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Mihiro Taniguchi 3-1-1, Sachimachi, Hitachi, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (56) References JP-A-52-151842 (JP, A) JP-A-63-245274 (JP, A) JP-A-4-42725 (JP, A) 4-344173 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02M 7/155

Claims (4)

(57) [Claims] (1)AC power from the AC system to DC power,
Or convert DC power from DC system to AC power
A power converter and a high voltage flowing out of the power converter into an AC system.
Suppress harmonic current or harmonic voltage applied to AC system
A reactor provided on the AC side of the power converter
And a harmonic filter comprising a capacitor and a capacitor.
In the force converter, Failure detection means for detecting a failure of the harmonic filter; The operation of the power converter in response to the detection signal of the failure detection means.
Power converter operation stopping means for stopping the operation,  The failure detecting means includes a core constituting the harmonic filter.
Current detector that detects the capacitor current flowing through the capacitor
A rectifier circuit for converting a detection signal of the current detector into a DC signal
Signal level determination for determining the level of the output signal of the rectifier circuit.
And a power conversion circuit based on the determination result of the signal level determination circuit.
Switch operation is stopped.RudenForce converter
Place. (2)AC power from the AC system to DC power,
Or convert DC power from DC system to AC power
A power converter and a high voltage flowing out of the power converter into an AC system.
Suppress harmonic current or harmonic voltage applied to AC system
A reactor provided on the AC side of the power converter
And a harmonic filter comprising a capacitor and a capacitor.
In the force converter, Failure detection means for detecting a failure of the harmonic filter; The operation of the power converter in response to the detection signal of the failure detection means.
Power converter operation stopping means for stopping the operation,  The failure detecting means detects that the harmonic current flows out to the AC system side.
Harmonic detection circuit that detects the harmonic voltage generated based on the
And a rectifier for converting an output signal of the harmonic detection circuit into a DC signal.
A circuit for determining a level of an output signal of the rectifier circuit;
And a power conversion circuit based on the determination result of the signal level determination circuit.
Switch operation is stopped.RudenForce converter
Place. (3)AC power from the AC system to DC power,
Or convert DC power from DC system to AC power
A power converter and a high voltage flowing out of the power converter into an AC system.
Suppress harmonic current or harmonic voltage applied to AC system
A reactor provided on the AC side of the power converter
And a harmonic filter comprising a capacitor and a capacitor.
In the force converter, Failure detection means for detecting a failure of the harmonic filter; The operation of the power converter in response to the detection signal of the failure detection means.
Power converter operation stopping means for stopping the operation,  The failure detecting means includes a capacitor of the harmonic filter.
From a series circuit of a capacitor and a resistor connected in parallel to
A harmonic detection circuit, and a voltage between both ends of the resistor of the harmonic detection circuit to a DC signal.
A rectifier circuit for converting, and a signal level determiner for determining a level of an output signal of the rectifier circuit.
And a power conversion circuit based on the determination result of the signal level determination circuit.
Switch operation is stopped.RudenForce converter
Place. 4. The power converter operation stopping means includes a logic circuit that takes a logical product of a determination output of the signal level determination circuit and a pulse output of a gate pulse generation circuit that generates a gate pulse to be supplied to the power converter. The power converter according to any one of claims 1 to 3 , wherein the power converter is configured to include the power converter.