JP6023034B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device, and more particularly to a power conversion device having standby redundancy.

  As one of power converters for driving an AC motor, there is a power converter that converts a commercial AC power source into DC and converts the DC into AC power again. There are several types of power converters depending on the power switching elements and power conversion methods used. Among these, power conversion devices using an element such as an IGBT having a self-cutoff capability as a switching element can use a pulse width modulation method (hereinafter referred to as PWM), and therefore can output an alternating voltage close to a sine wave, like an electric motor. Since an alternating current with less harmonics can be supplied to a load having a large inductance component, it is used in various application fields.

  Among the application fields using such a power converter, there is a field that requires continuous operation without stopping for several years. Although the continuous operation performance and failure rate of the power converter itself are improving year by year, in general, the failure rate is not zero and the power converter is periodically stopped due to the use of parts with a limited life. It is necessary to perform maintenance work.

  Therefore, in the above application field, even if one power converter is stopped due to failure or periodic maintenance, the power converter is configured in parallel so that the system can continue operation, There is a case where a so-called redundant system is constructed in which a part is operated and the rest is in a standby state.

  Further, when the control device is configured redundantly, a redundant system is configured in which control is performed by one control device and the other control device is put on standby. Usually, since a plurality of power converters can be controlled by one control device, a redundant system is generally constructed by two control devices (see, for example, Patent Document 1).

JP 2008-31273 A (Overall)

  In a redundant system with two power converters, or in a redundant system of a control device described in Patent Document 1, normally, when one power converter or control device fails, the power converter or control that stands by instantaneously Switch to the device and continue operation. However, for faults caused by abnormalities on the load side, for example, DC overvoltage faults, even if the fault factor is temporary, the same content fault occurs at the moment of switching, and the system It becomes impossible to continue driving.

  The present invention has been made in view of the above problems, and its purpose is to enable continuous operation without stopping the system in the case of a temporary cause when performing redundant switching due to a DC overvoltage failure. The object is to provide a power converter.

  In order to achieve the above object, the power converter of the present invention converts two AC voltages supplied from an AC power source into DC by a converter, and supplies the DC voltage to an inverter through a DC capacitor to obtain an AC voltage. And a controller for controlling the speed of an AC motor with a speed detector according to a given speed command. The control device includes failure detection means for separately detecting whether each of the power converters has failed due to a DC overvoltage or has failed due to an abnormality other than the above, and during operation of one of the power converters, When the failure detection means detects a failure other than a DC overvoltage, the operation control of the power converter is switched to the other, and the failure is detected during operation of one of the power converters. When the output means detects a DC overvoltage fault, the operation control of the power converter is switched to the other only when the speed command is not less than the speed feedback detected by the speed detector. Yes.

  ADVANTAGE OF THE INVENTION According to this invention, when performing redundant switching by DC overvoltage failure, it becomes possible to provide the power converter device which enabled continuation of operation, without stopping a system in the case of a temporary factor.

The system block diagram of the power converter device which concerns on Example 1 of this invention. The system block diagram of the power converter device which concerns on Example 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, the power converter concerning Example 1 of the present invention is explained with reference to FIG. FIG. 1 is a system configuration diagram of a power conversion apparatus according to Embodiment 1 of the present invention.

  The power conversion device in FIG. 1A includes power converters 1A and 1B and a control device 3. Each of the power converters 1A and 1B converts an AC input supplied from an AC power source into a DC by a converter, and converts it again into an AC by an inverter via a DC capacitor. Then, the AC motor 3 is driven through a switch provided on each output side. Each inverter of power converters 1 </ b> A and 1 </ b> B converts a DC voltage into an AC voltage by turning on and off switching elements, which are components of the power converter, by a gate pulse supplied from control device 3.

  The rotational speed of the AC motor 3 is detected by the speed detector 4 and given to the control device 3 as a speed feedback signal. The state signals of the power converters 1A and 1B are given to the control device 3 as monitoring signals. Examples of the monitoring signal include a DC voltage, an output current, and an input current. When these monitoring signals exceed a predetermined threshold and become abnormal while the power converter 1A or 1B is in operation, it is determined that the power converter has failed as described later, and the standby power converter is operated. Switch.

  Hereinafter, the internal configuration of the control device 3 will be described with reference to FIG. Usually, a speed command given from the outside is given to the subtractor 31. Then, the speed feedback signal detected by the speed detector 4 is subtracted from the speed command by the subtractor 31, and the output is given to the speed controller 32. The speed controller 32 outputs a voltage reference so that the inputted deviation becomes small, and gives it to the output converter 33. Normally, a current controller is provided after the speed controller 32, but this is not shown in FIG. 1 (b). In the output converter 33, the gate pulse is output so that the output voltage of the power converter 1 </ b> A or 1 </ b> B during operation becomes a voltage reference that is the output of the speed controller 32. Normally, PWM control is performed here. The output of the output converter 33 is given to the switch 34. In the switch 34, the selection switching of the gate pulse is performed in accordance with a command as to which of the power converters 1A and 1B is selected for operation.

  The monitoring signals of the power converters 1A and 1B are supplied to the failure detectors 35A and 35B, respectively. In each of the failure detectors 35A and 35B, it is determined whether or not the monitoring signal exceeds a threshold value. When the monitoring signal exceeds the threshold value, a failure signal is output. Here, there are two types of failure signals. When the monitoring signal exceeding the threshold value is a DC overvoltage, the failure signal (1) is output, and in the case of other failure signals, the failure signal (2) is output separately. Each failure signal (2) from the failure detectors 35A and 35B becomes one input of the OR circuits 36A and 36B, respectively. Since the outputs of the OR circuits 36A and 36B are given to the switch 34, the gate pulse output is instantaneously switched when the failure signal (2) is received.

  The deviation signal which is the output of the subtracter 31 is given to the positive value detectors 37A and 37B, respectively. The positive value detectors 37A and 37B each determine whether the deviation signal is positive or negative. When the deviation signal is a positive signal including zero, one logic is input to one input of the AND circuits 38A and 38B. Give a signal. Fault signals (1) from the fault detectors 35A and 35B are supplied to the other inputs of the AND circuits 38A and 38B, respectively, and the outputs of the AND circuits 38A and 38B are the other of the OR circuits 36A and 36B, respectively. Input.

  According to the configuration of the first embodiment described above, when a failure is detected by the failure detectors 35A and 35B, the gate pulse output is instantaneously switched to the standby power converter when the failure is other than a DC overvoltage. In the case of a DC overvoltage, the gate pulse output is switched to the standby-side power converter only when the rotational speed of the AC motor 2 becomes equal to or less than the speed command. In this way, for example, when the AC motor 2 is in operation, when the load is suddenly reduced and the regenerative operation becomes a direct current overvoltage, the power converter is instantaneously switched to the standby side during the regenerative operation. It becomes possible to prevent a DC overvoltage failure. The same applies to the case where an external force is applied and the speed exceeds the speed command during operation of the AC motor 2.

  Hereinafter, the power converter device which concerns on Example 2 of this invention is demonstrated with reference to FIG. FIG. 2 is a system configuration diagram of the power conversion apparatus according to the second embodiment of the present invention.

  About each part of this Example 2, the same part as each part of the power converter device which concerns on Example 1 of this invention of FIG. 1 is shown with the same code | symbol, and the description is abbreviate | omitted. The second embodiment is different from the first embodiment in that two power converters 1A and 1B are used as one power converter 1 in the system configuration of FIG. 2A, and one control device 3 is used. The point is that two redundant systems of the control devices 3A and 3B are used. In FIG. 2B, the control device 3 of FIG. 1B has a common internal block configuration but is separated into two control devices 3A and 3B. Since the internal block configuration of 3B is the same, only the control device 3A is shown, and the control device 3B is not shown.

  In FIG. 2A, the power converter 1 is configured to operate with a gate pulse supplied from either the control device 3A or the control device 3B. The monitoring devices from the power converter 1 and the speed feedback signal from the speed detector 4 are supplied in parallel to the control devices 3A and 3B. That is, in this case, the power converter 1 is a standby redundant system that is operated by either the control device 3A or the control device 3B and the other is on standby. In the case of such a redundant system of control devices, when the operating control device fails, the system is configured to switch to the standby control device.

  However, in the system configuration of the power converter of FIG. 2A, when the monitoring signal of the power converter 1 becomes abnormal and the failure detector of FIG. The abnormality may be caused by a failure of the operating control device and a failure that is not detected by the control device. In such a case, it may be possible to continue the operation by switching the operating control device to the standby control device, so the control device is switched even when the monitoring signal becomes abnormal. . As shown in FIG. 2B, when a failure is detected by the failure detector 35A during operation of the control device 3A, a failure signal (1) is output when the monitoring signal is a DC overvoltage, and other failures occur. In the case of a signal, it is separated and output as a failure signal (2). The failure signal (2) from the failure detector 35A becomes one input of the OR circuit 36A. Since the output of the OR circuit 36A is given to the switch 34A, when the failure signal (2) is received, the gate pulse output is instantaneously switched to the other control device. That is, in the case of the second embodiment, the switch 36A performs on / off switching. In order to exclusively switch between the control device 3A and the control device 3B, the output of the OR circuit 36A is provided to the switch of the control device 3B. As in the case of the first embodiment, when the failure signal detected by the failure detector 35A is the failure signal (1), this signal is given to one input of the AND circuit 38A. Then, the output signal of the positive value detector 37A is given to the other of the AND circuit 38A.

  According to such a system configuration shown in the second embodiment, for example, during operation of the AC motor 2, the load is suddenly reduced to become a regenerative operation, resulting in a DC overvoltage, and a control device for the challenge of the possibility of continued operation. When the operation is switched, it becomes possible to prevent the DC overvoltage failure again due to the instantaneous switching of the power converter to the standby side during the regenerative operation.

  Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, in FIG. 1B of the first embodiment, the failure detection circuit 35B, the OR circuit 36B, the positive value detector 37B, and the AND circuit 38B are all omitted, and the monitoring signal for the power converter 3B is supplied to the failure detector 35A. An input configuration may be used. In this case, the switch 34 only needs to reversely select the power converter to be operated by the signal from the OR circuit 36A. Similarly, in the case of the second embodiment, the monitoring signal of the power converter 3B can be input to the failure detector 35A of FIG. 2B.

  Further, in each embodiment, it has been described that the monitoring signal is supplied from the power converter to the control device. However, the power converter has a failure detector on the power converter side, and the failure signal (1) and the failure signal ( It is good also as a structure which gives 2) to a control apparatus.

  Furthermore, although the converter of the power converter in each embodiment is illustrated as a diode converter having no regenerative capability, it may be a converter having a regenerative capability with a capacity equal to or lower than the rated capacity of the power converter. Further, the power conversion devices 1, 1A, 1B may be formed by connecting a plurality of power conversion devices in parallel, and the power regeneration device has a capacity of regenerative capacity equal to or lower than the rated capacity of the power conversion device in parallel with these power conversion devices. A configuration in which a certain regenerative converter is connected may be used.

1, 1A, 1B Power converter 2 AC motor 3, 3A, 3B Controller 4 Speed detector 5 Speed detector 31, 31A Subtractor 32, 32A Speed controller 33, 33A Output converter 34, 34A Switch 35A, 35B Fault detector 36A, 36B OR circuit 37A, 37B Positive value detector 38A, 38B AND circuit

Claims (3)

Two power converters for obtaining an AC voltage by converting an AC voltage supplied from an AC power source into a DC by a converter and applying the DC voltage to an inverter through a DC capacitor;
The power converter is configured to select and monitor one of the power converters, and to control the speed of an AC motor with a speed detector according to a given speed command.
The control device includes:
It comprises a failure detection means for distinguishing and detecting whether each of the power converters has failed due to a DC overvoltage or a failure other than this,
When the failure detection means detects a failure other than DC overvoltage during operation of one of the power converters, the operation control of the power converter is switched to the other,
When the fault detection means detects a DC overvoltage fault while operating one of the power converters, the operation of the power converter is performed only when the speed command is greater than or equal to the speed feedback detected by the speed detector. A power converter characterized by switching control to the other. A power converter that converts an alternating voltage supplied from an alternating current power source into a direct current by a converter, and obtains the alternating voltage by applying the direct current voltage to an inverter via a direct current capacitor;
The power converter comprises two control devices that monitor the operation of the power converter and control the speed of an AC motor with a speed detector according to a given speed command.
Each of the control devices
A failure detection means for detecting whether the power converter has failed due to a DC overvoltage or a failure due to other abnormality is provided,
When the failure detection means detects a failure other than DC overvoltage during operation of the power converter using one control device, the operation control of the power converter is switched to the other control device,
When the fault detection means detects a DC overvoltage fault while operating the power converter using one control device, the power is only supplied when the speed command is greater than or equal to the speed feedback detected by the speed detector. A power conversion device characterized in that the operation control of the converter is switched to the other.   The power converter according to claim 1, wherein the converter is a diode converter.

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