JP3245728B2 - 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 improvement in reliability of a semiconductor power converter, and more particularly to a power converter having a multiplexed control system.

[0002]

2. Description of the Related Art It has been desired to operate a power converter without stopping at all, regardless of whether it is for general industrial use or for power use. For this reason, control systems have often been multiplexed. In this case, a protection circuit is provided at the output section of the multiplexed control system in order to ensure reliability and safety. In this protection circuit, the control system is switched by the switching command in any state of the output section of the control system. Therefore, the control signal for executing the prevention of the short circuit of the power converter and the prevention of the element failure loses its effect during that time. In order to avoid this, another protection circuit is required separately from the protection circuit. In such a configuration, not only the number of protection circuits that perform exactly the same operation increases, but also the control response is affected, and the increase in the number of protection circuits increases the total number of elements and increases the failure occurrence rate. Will be lost.

[0003]

On the other hand, Japanese Patent Laying-Open No. 3-7068 has a multiplexed control circuit.
The operation control can be restarted immediately by detecting a failure of each control circuit and automatically executing a failure reset when a failure is detected to select a sound control circuit.

However, in this method, when the control target is not always operable, and the output state of the control target changes during switching from the output of the failed control device to the output of the normal control device, an arbitrary time is required. When the switching operation is performed, the control target may cause abnormal operation or failure due to a difference in output state. For example, a gate turn-off thyristor (hereinafter referred to as G
Abbreviated as TO. ) The switching frequency is several hundred H
z is the limit, and when a switching pulse exceeding that frequency is output by the above-described switching operation, GT
O may break down.

[0005] Further, even in a transistor element such as an insulated gate bipolar transistor (IGBT) capable of high-speed switching, although the failure is reduced for the above reason, it is necessary to prevent a sudden change in the output current value of the power converter at the time of switching. is there.

In order to ensure an appropriate switching signal, it is necessary to provide a protection circuit at the output of the switching device, or to provide a means for setting the execution time of the switching to an appropriate time. An object of the present invention is to provide a power conversion device having a multiplex control system, which prevents an abnormal switching signal from being output to a switching element when the control system is switched.

[0007]

In order to achieve the above object, a power converter having a self-extinguishing switching element connected in a bridge and a plurality of control devices for controlling the detected operation amount of the power converter are provided. with the door, in the power conversion apparatus that outputs a control signal is always the control device, wherein
A control that controls the power converter among the plurality of control devices.
Failure that outputs a switching signal when a failure of the control device is detected
Detecting means for detecting a failure in response to the switching signal;
Control signal from the output of another controller
A switching means for switching to and outputting a control signal according to the following formula; and, when the output of the switching means is switched, calculating a time for holding the switching element of the output of the switching means on. When the time is short, the ON control signal is not output, and when the time is long, the ON control signal is output after the elapse of the arm short-circuit prevention time, and a protection unit that holds the ON control signal until the set time elapses. A power converter is provided.

Further, the self-extinguishing switching element is bridged.
A power converter connected to the
And a plurality of control devices for controlling the operation amount of the vessel.
A power conversion device for outputting one control signal of the control device
In the plurality of control devices, the power converter
Switching signal when a failure of the controlling device is detected
Failure detection means for outputting the
When the output signal of the control device in which the failure is detected and the output signal of the switched control device become the same signal after a lapse of a set time after the failure detection,
Switching time setting means for outputting the held switching signal ,
In response to a switching signal from the output of the switching time setting means.
Control signal based on the output of the controller in which the failure was detected.
The power conversion is performed by switching to a control signal based on the output of another controller.
Switching means for outputting to the converter.
Power converter.

It is preferable that the set time is a minimum time to be held which is determined by the on / off switching characteristics of the self-extinguishing switching element.

[0010]

According to the present invention, the above-mentioned object is achieved by the following operation according to the present invention.

[0011] In a power conversion device in which a self-extinguishing switching element having a plurality of control devices is bridge-connected, only one control device is operated during operation of the device, and the other control devices are stopped. The method may be a method in which an appropriate number is always operated and one of the signals is used. If a fault occurs in the operating control device and is detected by the fault detecting means, a switching signal is sent to another normally stopped control device or another operating control device, and immediately the switching means is used. Switching to output has been performed conventionally.

However, at this time, it is sufficiently predicted that the control signal output at the time of occurrence of the failure and the switched signal are not completely synchronized. Therefore, it can be considered that the signal output from the switching unit is often an abnormal signal that is not a normal pattern. Therefore, if the switching circuit is controlled with the control signal at the time of switching, an operation exceeding the limits of the switching circuit and the switching element itself may be required. This can be avoided by the following means.

The pattern of the signal generated at the time of switching can be easily calculated from the time lapse of the fault signal and the selected signal until the switching. Operations that pose a problem include short-circuiting the arm of the bridge connection and causing the switching element to perform a severe on / off operation. The former is determined by including the circuit, and the latter is the minimum time to be held which is determined by the ON / OFF switching characteristics of the self-extinguishing switching element.

On the basis of the ON operation pattern of the signal, the ON operation signal at the timing when the bridge connection arm short circuit occurs is avoided by not outputting the ON control signal by the protection means during the arm short circuit prevention time. Also,
In the latter case as well, until the minimum time for which the self-extinguishing switching element should be held has passed, the control for holding the ON signal is output by the protection means, so that the operation can be safely performed.

Further, if the signal is switched immediately after the failure is detected, the above-mentioned abnormal signal may be output.
The output signal of the control device in which the failure is detected is output as it is until a minimum time to be held determined by the characteristics at the time of switching on and off of the self-extinguishing switching element is output as it is,
After that, the output signal of the switched control device may be switched to the output of the switching device by the switching time setting device after waiting for the same output signal. In this case, there is no sudden change in the signal after the switching, so that the switching operation is in a normal range.

In this manner, in the power converter having a multiplex control system, it is possible to obtain a power converter in which an abnormal switching signal is not output to the switching element when the control system is switched.

[0017]

An embodiment of the present invention will be described below with reference to FIG.

The DC power supply 1 is converted into AC by a bridge-connected DC / AC converter 2 using a semiconductor switching element and supplies power to a load 3. The switching element performs a switching operation based on a control signal selected from the multiplex control system. The current, which is one of the operation amounts of the load 3, is detected by the current detectors 4a and 4b, and
a and 5b, and information is output from the control devices 5a and 5b to the failure detecting means 6. Each control device 5
a. 5b receives one current detection signal in common, or receives it from the detectors 4a and 4b corresponding to each, and performs arithmetic processing relating to control. Each control device 5a. 5
In b, an operation such as making the load current value constant by a control command (not shown) is performed, and the control amount is modulated based on pulse width modulation (hereinafter abbreviated as PWM) control.
Output to the switching element as a switching pulse.

The failure detecting means 6 detects a failure or an operation stop state of each control device by detecting and checking a circuit state, a calculated value, an operation power supply, an output state, etc. of each control device, and outputs a failure signal. . When a failure occurs in a control device that is not outputting to the power converter 2 or a stopped control device, the failure detection means 6 displays a corresponding display and takes out the control device while the power converter 2 is operating. , Can be returned after repair.

When a failure occurs in the control device controlling the power converter 2, the switching means 7 takes in the output of the failure detection means 6 and selects a normal control output from the control device based on the state of the signal. , To the power converter 2. At this time, the switching means 7 performs switching based on the switching signal output when a failure occurs. Therefore, the switching means 7 outputs the power to the power converter 2 at the stage of transition from the output of the failed control device to the output of the normal control device. Control signal may include a steep change.
As a result, the switching element of power converter 2 that has received the control signal cannot fully cope with the change, and may cause abnormal operation or failure. Therefore, after the switching means 7,
A protection unit 8 for protecting the power converter 2 from the above-described abnormality is provided.

FIG. 3 shows an example of a sudden change in the control signal generated when the switching signal is input. The power converter 2 is a large-capacity self-excited converter, has a bridge connection configuration in which GTO is used as a self-extinguishing element and is connected in anti-parallel with a flywheeling diode. In FIG. 3, (1) is a control device 5a.
Output pulse, (2) output pulse of control device 5b, (3)
In the figure, (4) is an enlarged view of the pulse at the switching time, and (4) is an enlarged view of the pulse at the switching time.

Assuming now that the output pulse of the switching means 7 changes from the output pulse of the control device 5a to the output pulse of the control device 5b by the output signal of the failure detecting means, as shown in the enlarged partial pulse of the switching time, A pulse that is not seen in the control device 5a and the control device 5b and that has a very narrow time width and is equal to or shorter than T time is output. If the switching element is turned on by the pulse 1 and turned off by the pulse 1, the large-capacity GTO may cause an element failure. Therefore, the protection means 8 is inserted to remove such a pulse having a narrow time width. It is. As is clear from the figure, the detection of the time T can be easily performed by calculating the switching time and the time required for the output pulse of the control device 5b to be switched to change after the switching time.

FIG. 4 shows an operation example of a typical protection means 8 used for a large capacity GTO. In the drawing, X is an input pulse from the switching means 7 to the protection means 8, XP is a switching signal output to the P arm of the power converter 2 shown in FIG. 1, XN is a switching signal output to the N arm, and T is the above-described protection at the time of switching. The time width of the pulse input to the means 8, Td is the short-circuit prevention time provided so that the P-arm switching element and the N-arm switching element are not simultaneously turned on, and Tmin is the minimum determined by the characteristics when the GTO is switched on and off. The time width that must be held, 1 is the GTO on, and 0 is the GTO off signal.

In FIG. 4, (1) shows the operation when the input pulse of the protection means 8 is an ON pulse having a time width T shorter than Td. At this time, 0 is output to the output XP and 1 is output to XN. Next, (2) indicates that Tmin is larger than Td.
This is an operation when an on-pulse having a time width T shorter than the sum of Td and Td is input. At this time, XP has T more than X pulse.
One pulse of Tmin width is output with a delay of d, and becomes zero at X pulse input time to XN, and from that time, Tmin + 2T
It outputs 0 during d and returns to 1 again. (3) is a case where one pulse larger than Tmin + Td is input. At this time, XP is given by T−T with a delay of Td.
One pulse during the period d, XN, becomes 0 at the time when X becomes 1, outputs 0 during T + Td, and returns to 1 again.

Here, in any of the cases (1), (2) and (3), it is natural that the switching of the switching element is not executed during the normal operation during Td.

FIG. 5 shows an algorithm for achieving the functions described above. First, the input pulse signal X to the protection means 8 is input, and T and Td are compared. If T is smaller than Td, the operation shown in FIG. 4A is performed. If Td is larger, Tmin + Td is compared. Operation, if large, FIG.
The operation of (3) is performed. With these three actions,
When a similar 0 pulse is input as an input signal, the operations of XP and XN are opposite to the relationship of XP and XN in (1), (2), and (3) of FIG. Shall be performed. In this way, a failure signal is output at the time of failure detection, and the switching means 7 outputs an abnormal switching signal to the control output of the control device even if the switching operation is performed at an arbitrary time when the switching signal is input. As a result, the output current of the power converter 2 does not suddenly change, and the output current waveform can be improved.

After switching the control device, it is possible to take out the switched control device while operating the power converter 2 and perform maintenance and inspection such as returning after repair.
The operation rate, reliability and safety can be improved.

The protection means 8 conventionally provided at the output section of each control device is integrated into the protection means 8 after the switching means 7, and has the same safety and control as when no multiplex control system is formed. Responsiveness is maintained at the same time. In FIG.
Although the control device is shown as a double system, it can be realized by a similar configuration even if it is a multiplex system. In this case, even if a failure occurs, the multiplex control system can be maintained even while the control device is taken out and repaired,
Further, the operation rate, reliability, and safety can be improved.

FIG. 2 shows another embodiment of the present invention. The switching time setting means 9 is provided between the failure detecting means 6 and the switching means 7 in place of the protection means 8 in the above embodiment. The switching time setting means 9 delays the switching time until a failure occurs in any of the control devices until the time allowed for the switching element.

FIG. 6 shows an operation example of the switching time setting means 9. In the figure, the same components as those in FIG. 4 are represented by the same symbols. Each of the control devices 5a and 5b outputs the switching pulses of the P-arm and the N-arm while securing the short-circuit prevention time Td and the minimum pulse width Tmin necessary for the switching of the power converter 2. When the output of the control device 5a is being output to the power converter 2, a failure occurs in the control device 5a, and the output is switched to the output of the control device 5b.

(1) is a case where the output of the control device 5b which is switched to the faulty control device 5a is the same when Tmin elapses after the detection of the fault. In this case, since the output of the XP is 1 after the occurrence of the failure, the signal of 1 is held at the output for Tmin for the above-mentioned protection, and then the signal of the control device 5b is changed to the output of the control device 5a. Since they are the same, switching is performed.

(2) The case where the signal of the control device 5b differs from the signal of the control device 5a when Tmin has elapsed. In this case, the output state is held until the same state is reached. That is, the output of the switching means 7 is held during Thlt. Switch at the same time. When a similar off-pulse is input as an input signal in these two operations, the operations of XP and XN are described in (1), (2), and (3) of FIG.
Is opposite to the relationship between XP and XN. As a result, it is possible to prevent the output of the switching means 7 from outputting a signal that causes an abnormal operation or a failure to the power converter 2, thereby preventing a sudden change in the output current of the power converter device and improving the output current waveform. It can be performed. With this configuration, the same effect as in the above-described embodiment can be obtained.

FIG. 7 shows an example of the switching means 7. It can be configured with a simple logic circuit. In the above embodiment,
Although an example of a power inverter is described, not only in the case of a power forward converter, but also in a power converter using a semiconductor switching element such as an uninterruptible power supply using a power forward converter and a power inverter. Obviously, it is also applicable.

[0034]

As described above, according to the present invention, in a power converter having a multiplex control system, the switching timing is determined by the length of the signal time for switching between the control systems. The output of the accompanying abnormal switching signal can be prevented. Therefore, maintenance and inspection of the failed control device can be performed while the operation of the power converter is continued.
As a result, there is an effect of improving the operation rate, safety, and reliability of the power converter.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram illustrating a fault pulse generated when the control device is switched.

FIG. 4 is a diagram illustrating an operation example of a protection unit.

FIG. 5 shows an example of an algorithm of a protection unit.

FIG. 6 is a diagram illustrating an operation example of a switching time setting unit.

FIG. 7 shows an example of a switching unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Power converter 3 Load 4a, 4b Current detector 5 Multiplexing control device 5a, 5b control device 6 Failure detection means 7 Switching means 8 Protection means 9 Switching time setting means

Continuing from the front page (72) Inventor Hiroyasu Sato 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Inventor Shoichiro Furuseki 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Stock (56) References JP-A-4-372522 (JP, A) JP-A-3-7068 (JP, A) JP-A-5-137244 (JP, A) JP-A-5-30683 (JP, A) JP-A-5-114473 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/537 H02M 1/00

Claims (3)

(57) [Claims] 1. A power converter having a self-extinguishing switching element connected in a bridge, and a plurality of control devices for controlling a detected operation amount of the power converter. In a power conversion device that outputs a control signal, the power conversion device controls the power converter among the plurality of control devices.
Switching signal is output when the controller
Failure detecting means for responding to the switching signal;
Control signal based on the output of the controller
Switching means for switching to and outputting a control signal based on the output of the device; and calculating the time for keeping the switching element of the output of the switching means on when the output of the switching means is switched. When the time is shorter than the prevention time, the ON control signal is not output. When the time is longer, the ON control signal is output after the elapse of the arm short circuit prevention time, and the ON control signal is held until the set time elapses. power conversion apparatus characterized by comprising a means. 2. A power converter comprising a self-extinguishing switching element connected in a bridge, and a plurality of control devices for controlling the detected operation amount of the power converter. In a power conversion device that outputs a control signal, the power conversion device controls the power converter among the plurality of control devices.
Switching signal is output when the controller
The failure detection means, and the output of the failure detection means.
Holding the switching signal, the when the output signal of the output signal and the switching is the control unit of the control device a failure is detected after the time set after fault detection has elapsed it becomes the same signal
Switching time setting means for outputting the held switching signal ;
In response to the switching signal from the output of the switching time setting means,
The control signal based on the output of the controller
Power conversion apparatus characterized by comprising a switching means for <br/> output Te switching the control signal by the output of the control device to the power converter. 3. The power conversion device according to claim 1, wherein the set time is a minimum time to be held which is determined by an ON / OFF switching characteristic of the self-extinguishing switching element. .