JPH04264271A - Method for testing power converter - Google Patents

Abstract

PURPOSE:To facilitate load operation test of a power conversion apparatus with which reliability of a non-failure power supply apparatus or the like is required without preparing a load apparatus. CONSTITUTION:In a power conversion apparatus comprising two power converters 13a to 13b connected in parallel including a PWM converter 130 which can operate with either a positive or negative input power factor and a PWM inverter 113 for converting direct current of the PWM converter 130 into alternate current, the PWM converter of one of the converters is operated at a positive power factor to output power while the PWM converter of the other power converter is operated at a negative power factor to recover the power to an ac input power source. Thus load operation characteristics of the respective power converters can be tested.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

[Industrial Application Field] The present invention is a power converter test that can grasp the load operation characteristics of a power converter without preparing a load device for a load operation test of a power converter that requires reliability. It is about the method.

0002

2. Description of the Related Art An example of a power converter to which the present invention is applied is an uninterruptible power supply. The prior art will be explained below with reference to an uninterruptible power supply. Uninterruptible power supplies are the key to supporting advanced information and communication systems, as introduced in, for example, "Magazine OHM, 90/11, Special feature 'Towards the introduction of large-capacity uninterruptible power supply systems'" published by Ohmsha. -They are used as components in a wide range of fields, and their mission is to provide high reliability.

FIG. 3 shows an example of an uninterruptible power supply system using an uninterruptible power supply. In this figure, 10 is an input AC power supply, 11a and 11b are uninterruptible power supplies, 12 is a load, and 11
1 is a converter, 112 is a capacitor, 113 is an inverter, and 114 is a transformer. In FIG. 3, when the input AC power supply 10 is healthy, power is supplied to the load 12 via two uninterruptible power supplies 11a and 11b operating in parallel. At this time, the AC power of the input AC power supply 10 is converted to the converter 111.
The DC power is converted into DC power, smoothed by a capacitor 112, and converted back to AC power by an inverter 113, which is then supplied to the load 12 via a transformer 114. When the input AC power supply has an abnormality such as instantaneous voltage drop, the capacitor 112
The inverter 113 converts direct current power such as power from a storage battery (not shown) into alternating current power in the same way as the transformer 11.
Since the power is continuously supplied to the load 12 via the power supply 4, stable alternating current power can be continuously supplied to the load without interruption.

[0004] Such uninterruptible power supplies 11a and 11b
The required characteristics are that stable load operation is possible. On the other hand, in factory tests and on-site installation tests of the uninterruptible power supplies 11a and 11b, the load 12 is not prepared, and in order to confirm stable load operation and temperature rise of the device through load operation tests, an equivalent load must be prepared. I needed to prepare. In addition, when trying to understand the load operating characteristics in the same way during regular inspections after on-site installation, load 12 is a load such as a computer that operates continuously 24 hours a day, 365 days a year, so load 12 is It was necessary to switch to direct feed from the input AC power supply 10 and operate continuously, and prepare an equivalent load in place of this for testing. From the above points, the conventional uninterruptible power supply testing method has the following problems.

(1) In order to understand the load operation characteristics of the uninterruptible power supplies 11a and 11b, it was necessary to prepare an equivalent load. Also, the connecting wires between each device must be thick enough to withstand the actual load current.
Particularly in cases such as on-site installation tests, where the installation location of an equivalent load is restricted due to conditions such as an intelligent building in a city center, the time, effort, and cost required for test preparation are extremely high. (2) In addition, in tests to understand load operating characteristics, power consumption is consumed with an equivalent load, resulting in extremely high power consumption charges. (3) When performing load operation for periodic inspection of the uninterruptible power supplies 11a and 11b, etc., as described above, in order to directly supply power to the load 12 from the input AC power supply 10,
Even if an equivalent load was prepared, the power capacity of the input AC power supply 10 was insufficient, and it was often impossible to carry out a substantial load test.

[0006]

[Problems to be Solved by the Invention] As described in the prior art with reference to FIG. 3, important power conversion devices such as uninterruptible power supplies require Often used to test driving characteristics. In order to check such load operation characteristics, a load device is required to flow the load current to the power converter, and with conventional technology, it is difficult to use the actual load of the power converter as the load device. For this reason, equivalent load devices such as water resistors were prepared to check the load operating characteristics. There are relatively many opportunities to check such load operation characteristics, and this is generally done in the following cases. (a) Factory testing upon completion of manufacturing of power conversion equipment. (b) Customer-attended testing of power conversion equipment. (c) On-site installation test of power conversion equipment. (d) During periodic inspections that are performed every few years after the power conversion equipment has been put into operation. This is a test to check the load operation characteristics of a power converter, but conventionally, when testing a power converter, there have been the following problems as mentioned above.

(1) An equivalent load device that can carry the load current of the power conversion device had to be prepared every time a test is conducted. (2) The connecting wires between the input AC power supply and each power converter, and between each power converter and equivalent load devices must also be thick enough to withstand the actual load current, and test preparation costs such as construction costs are required. was very expensive. (3) Electric power consumption for testing actual load operating characteristics also increased, and test costs were also high. (4) In order to pass the actual load current during factory tests and periodic inspections, a certain amount of input AC power supply capacity is required.
Due to the lack of input AC power supply capacity, there were cases in which the test period was extended until the input AC power capacity was secured, and in some cases, the test could not be completed sufficiently.

Therefore, an object of the present invention has been made in view of the above-mentioned points. It is an object of the present invention to provide a test method for a power converter that allows a current equivalent to the load current to flow through the power converter to ascertain the load operation characteristics of the power converter. [Structure of the invention]

[0009]

[Means for Solving the Problems] A power converter to which the present invention is applied in order to achieve the above object, as shown in FIG. - two power converters (13a, 13b) consisting of a converter 130 and a PWM inverter 113 that converts the DC output of the PWM converter 130 to AC are connected in parallel to convert the AC power of the input AC power supply 10. It is characterized in that it is configured to convert the power and feed it to the load 12.

0010

[Operation] By configuring as described above, for example, if the PWM converter 130 of the power converter 13b is operated with a negative input power factor, the power converter 13b will be connected from the power converter 13a to the
Electric power is supplied to the AC input power source 10, and this electric power is regenerated to the AC input power source 10 by the power converter 13b. Moreover, the power converter 13
When the PWM converter 130 of a is operated with a negative input power factor, power is supplied from the power converter 13b to the power converter 13a, and this power is regenerated to the AC input power source 10 by the power converter 13a. Therefore, power converters 13a and 1
There is no need to prepare a special load device in order to understand the load operation characteristics of each of the input AC power supplies 10 and 3b. The power supply capacity of the input AC power supply 10 may be small. Therefore, according to the power conversion device testing method of the present invention, there is no need to prepare a special load device;
The power consumption is very low and economical, and the load characteristics of the power converter can be easily grasped in a short period of time.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the block diagram of FIG. In this figure, 13a and 13b are power converters 1 used as uninterruptible power supplies, for example.
30 is a PW that can be operated with positive input power factor and negative input power factor
M converter, 112 is a capacitor, 113 is a PWM inverter that converts the direct current of the PWM converter 130 into alternating current.
This PWM inverter 113 can have the same configuration as the PWM converter 130. Therefore, PWM converter 130 and PWM inverter 113 are arranged symmetrically when viewed from their DC circuit. Also 114
is the output transformer of the power converter 13.

When the configuration shown in FIG. 1 functions as a power converter, AC power from the input AC power supply 10 is converted to DC power by the PWM converters 130 of the power converters 13a and 13b, and then converted to DC power by the capacitor 112. This power is smoothed and converted back into AC power by a PWM inverter 113, which is then supplied to the load 12 via a transformer 114. PWM converter 13 applied to the embodiment of the present invention in FIG.
A specific circuit example of 0 is shown in FIG. In this diagram, 130 is PW
M converter, 132 is an AC input terminal, 133 is an AC reactor, 134 is a DC output terminal, 135 is a current detector, 136 is a voltage detector, 137 is a voltage reference, 138 is a voltage controller, 139 is a multiplier, 140 is a current controller, 14
1 is a PWM control circuit.

The PWM converter 130 shown in FIG. 2 controls the voltage of the DC output terminal 134 with a voltage controller 138 in accordance with the set value of a voltage reference 137, and detects this control output signal with a voltage detector 136. Multiply the voltage of the AC input terminal 132 by a multiplier 139 to create a sine waveform current reference,
A current controller 140 controls the detection signal of the current detector 135 and the current reference so that the current flowing through the AC reactor 133 matches this current reference, and the PWM control circuit 141 controls the PWM converter 130 by this output signal. control.

The PWM converter 130 in FIG. 2 compares the output DC voltage with the voltage reference 137 and converts the DC output terminal 1.
When the voltage of 34 is low (generally when a load is applied), the AC input terminal 132-AC reactor 133-P
Power is supplied through a path from the WM converter 130 to the DC output terminal 134, and the input power factor of the PWM converter 130 is operated near positive 1.0. On the other hand, if the voltage at the DC output terminal 134 is higher than the voltage reference 137 (generally when there is power regeneration than the load), the multiplier 139
Since the current reference output from the DC output terminal 13 is negative,
4-PWM converter 130-AC reactor 133-
DC power is regenerated to the power supply side through the path of the AC input terminal 132, and at this time, the input power factor of the PWM converter 130 becomes around negative 1.0.

In this way, the converter 130 shown in FIG. 2 can adjust the power supply direction by setting the voltage reference 137, and the current reference output from the multiplier 139 is AC.
Since it is also the phase reference for the current flowing through the reactor 133, the input power factor of the converter PWM 130 can also be controlled.

Therefore, in FIG. 1, the power converter 13a
When the power converter 13b is operated and the voltage reference 137 of the power converter 13b is set lower than that of the power converter 13a, the power converter 1
The AC power output from AC power converter 3a can be regenerated to input AC power supply 10 through the path of output terminal 131 of power converter 13b - transformer 114 - inverter 113 - capacitor 112 - PWM converter 130. On the other hand, if the voltage reference 137 of the power converter 13a is set lower than that of the power converter 13b, the AC power output from the power converter 13b is lower than that of the power converter 13b.
3a can regenerate power to the input AC power source 10. At this time, the input power factor of the power converters 13a and 13b is near positive 1.0 for outputting power, and near negative 1.0 for regenerating power, which is required for input AC power source 10. The reactive power component is also very small.

As is clear from the above description, the power converter 13a has a PWM converter that can control the input power factor.
By connecting the power converters 13a and 13b in parallel and regenerating the output power of one power converter with the other power converter, it is possible to grasp the load operation characteristics of each of the power converters 13a and 13b. There is no need to prepare a load device, and the power supply capacity of the input AC power supply 10 is only required to correspond to the internal loss of the power converters 13a and 13b. Therefore, the power converters 13a and 13 can be easily connected in a shorter period of time than before.
It is possible to understand the load operation characteristics of b.

In the above explanation, power converters 13a, 13
Although the explanation has been given with reference to an uninterruptible power supply as b, it is clear that the present invention can be applied to any power converter having a converter that can control the input power factor.

Furthermore, although there is no limitation as to whether or not the PWM inverters 113 of the power converters 13a and 13b in FIG. PWM converter that regenerates
The output voltage of the PWM inverter 113 on the side of the converter 130 may also be decreased in response to the decrease in the voltage reference 147. It is clear that various other design changes and configurations can be made without changing the gist of the present invention.

[0020]

As is clear from the above description, according to the present invention, it is possible to provide a testing method for a power conversion device that can obtain the following effects. (1) There is no need to prepare a special load device when performing a load operation characteristic test of a power conversion device. (2) Since a current equivalent to the load current flows only between the power converters, there is no need for special wire connection work for the test, and test preparation costs can be significantly reduced. (3) Since no special load device is required, there are no restrictions on test locations, etc., and the test method according to the present invention requires very little power consumption, so testing costs can be significantly reduced. (4) Since the test method of the present invention requires only a small input AC power supply capacity, restrictions on test timing and test period can be removed, and tests can be performed more easily, economically, and in a shorter period of time than in the past.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention using a single line connection.

FIG. 2 is a block diagram showing an example of the configuration of a PWM converter that can control the input power factor used in the present invention.

FIG. 3 is a block diagram showing an example of a conventional device using a single line connection.

[Explanation of symbols]

10... Input AC power supply, 11a, 11b... Uninterruptible power supply, 12... Load, 13a, 13b... Power converter, 111...
Converter, 112... Capacitor, 113... Inverter, 114... Transformer, 130... PWM converter, 131
...output terminal, 132...AC input terminal, 133...AC reactor, 134...DC output terminal, 135...current detector,
136... Voltage detector, 137... Voltage reference, 138... Voltage controller, 139... Multiplier, 140... Current controller, 141
...PWM control circuit.

Claims (1)

[Claims] [Claim 1] Two power converters each consisting of a PWM converter that can be operated with a positive input power factor and a negative input power factor, and a PWM inverter that converts the direct current of this PWM converter into alternating current. In a test method for power converters connected in parallel to convert AC power from an input AC power source and supply power to a load, a PWM converter of one power converter of the power converter is connected to a positive input terminal. Each of the power converters is operated at a power factor to output power, and the PWM converter of the other power converter is operated at a negative input power factor to regenerate the power to the AC input power source. A method for testing a power conversion device, characterized in that a load operation characteristic test is performed.