JP5822041B1 - Power converter - Google Patents

Abstract

Provided is a power conversion device having a function of diagnosing a state of a shutoff switch that shuts off a power supply when a control power supply unit fails, and that can safely stop the device while protecting a circuit even when a duplicate failure occurs. In a power conversion device including at least an arithmetic processing unit 50A, a drive unit 60, a safety unit 40, a control power supply unit 10, and a power supply diagnosis unit 20A, the power supply diagnosis unit 20A includes a cutoff switch 23, a comparator 21, and a reference. And a transistor 22 that is a voltage changeover switch, and is configured to control opening and closing of the cutoff switch 23 using the diagnostic signal S1 output from the arithmetic processing unit 50A and the monitoring voltage output from the power supply diagnostic unit 20, The arithmetic processing unit 50A diagnoses the presence or absence of a short circuit failure or an open failure of the cutoff switch 23 based on the logic S1 of the diagnostic signal and the logic of the safety power supply signal S2 corresponding to the level of the monitoring voltage. The operation of the drive unit 60 by the PWM signal is stopped. [Selection] Figure 2

Description

  The present invention relates to a power conversion device such as an inverter device, a converter device, or a servo amplifier that drives an electric motor, and more specifically, a failure diagnosis function that performs a failure diagnosis of a control power supply unit and shuts off the control power supply, The present invention relates to a power conversion device having a safety function for stopping.

Electric motors are widely used in various fans and pumps installed in factories, elevators, machine rooms in buildings, drive parts of manufacturing equipment, etc., and these electric motors are usually power electronics such as inverter devices and servo amplifiers. It is driven by the power conversion device using.
If a failure or the like occurs in this type of power conversion device, the power conversion device or the electric motor may be damaged depending on the situation, which may cause danger to surrounding workers and users of the equipment.

Against this background, countries around the world are demanding that motor drive systems using power converters have safety functions based on international standards. This safety function must be ensured even when, for example, the control power supply unit of the power conversion device fails and an abnormality such as overvoltage occurs, and the required level of safety against failure varies depending on the application. .
For this reason, in order to further improve the safety of the motor drive system, a highly accurate failure diagnosis function for the control power supply unit, and when the failure occurs, the main power supply is shut off and the drive unit operation is stopped quickly. It is important to have a safety function to stop safely.

Here, FIG. 5 is a prior art in which a failure / abnormality of a power supply circuit of a CPU that performs various arithmetic processes in a power conversion device is detected and a predetermined safe operation / protection operation is performed. It is described.
In this prior art, two CPUs 71A and 71B capable of executing the same arithmetic processing, power supply circuits (control power supply circuits) 72A and 72B, power supply voltage supply / shut-off switches 73A and 73B, power supply voltage Voltage abnormality detection circuits 74A and 74B for detecting an abnormality. SA and SB are signals including operation information and control information between CPUs, XA and XB are voltage abnormality detection signals, and YA and YB are open / close signals of the switches 73A and 73B.

The operation of FIG. 5 will be described below.
First, in a state in which the switches 73A and 73B are turned on and the power supply voltage is supplied to the CPUs 71A and 71B, for example, the CPU 71A is a main system (active system) and the CPU 71B is a sub system (standby system). Is assumed to be executed. In this state, when the power supply circuit 72A fails and the power supply voltage of the CPU 71A becomes an overvoltage, the voltage abnormality detection circuit 74A transmits a voltage abnormality detection signal XA to the sub CPU 71B.
The sub CPU 71B recognizes the failure of the main power circuit 72A by the received voltage abnormality detection signal XA, shuts off the switch 73A by the shut-off signal YA, and stops the operation of the CPU 71A. And the arithmetic processing is continued.

With the above operation, it is possible to prevent a failure or breakage of the CPU 71A due to an overvoltage of the power supply voltage.
The operation when the power supply circuit 72B on the CPU 71B side fails is the same as described above.

WO2014 / 054349 (paragraphs [0018] to [0021], FIG. 1 etc.)

  In the prior art shown in FIG. 5, the abnormality of the power supply voltage is monitored and associated with each of the arithmetic processing systems made redundant by the two CPUs 71A and 71B. For this reason, the two switches 73A and 73B and the voltage abnormality detection circuits 74A and 74B are required, and there is a problem that the circuit configuration becomes complicated, the size is increased, and the cost is increased. The reason why the power supply circuits 72A and 72B are individually provided is to comply with a predetermined functional safety standard.

  Further, according to the prior art of FIG. 5, a failure of the switch 73A or 73B, for example, a short-circuit failure itself cannot be detected. Therefore, for example, when a so-called overlap failure occurs such that the switch 73A short-circuits in a state where the power supply circuit 72A fails and an overvoltage is applied, the CPU 71A, peripheral circuits, loads, and the like cannot be protected from the overvoltage.

  Furthermore, as another conventional technique, a power conversion device having a failure diagnosis function and a safety function of a control power supply unit is known. FIG. 6 is a block diagram mainly showing a control power supply voltage supply path in this power converter.

  In FIG. 6, the power supply voltage output from the control power supply unit 10 is supplied to the arithmetic processing unit 50, and the arithmetic processing unit 50 performs a predetermined arithmetic processing to generate a PWM signal. This PWM signal is sent to a drive unit 60 having a semiconductor switching element or the like constituting the inverter device, and the drive unit 60 drives a load such as an electric motor (not shown) by turning on and off the semiconductor switching element.

On the other hand, the control power supply voltage from the control power supply unit 10 is also supplied to the power supply diagnosis unit 20, the safety diagnosis unit 30, and the safety unit 40.
The power supply diagnosis unit 20 monitors the control power supply voltage. When an overvoltage exceeding a predetermined value is detected, the power supply path is cut off by the operation of the semiconductor element as a cut-off switch, and the subsequent safety diagnosis unit 30 and the safety unit 40 are turned on. Protect from overvoltage. At the same time, a signal is sent to the arithmetic processing unit 50, the output of the PWM signal is stopped, and the operation of the driving unit 60 is stopped.

  The safety unit 40 shuts off the main power supplied to the drive unit 60 when a failure other than the control power supply unit 10 occurs (for example, a short circuit failure of a semiconductor switching element in the drive unit 60). It has a function of safely stopping the operation of the power conversion device and the electric motor, and displaying or transmitting an alarm to the outside as necessary. The safety diagnosis unit 30 is for performing a failure diagnosis of the safety unit 40.

In the above configuration, even when an overvoltage exceeding an assumption occurs due to a failure of the control power supply unit 10, the safety diagnosis unit 30 and the safety unit 40 perform their original functions without causing the subsequent power supply diagnosis unit 20 or the like to propagate the overvoltage. In order to do so, it is necessary to allow the overvoltage when designing these circuits, or to ensure that the overvoltage is cut off.
When designing a circuit that can tolerate overvoltage, it becomes difficult to design using low-voltage and general-purpose integrated circuit components (arithmetic processing unit, comparator, etc.) and semiconductor elements (transistors, FETs, etc.) Need.

Therefore, conventionally, as described above, a method has been adopted in which an overvoltage generated due to a failure of the control power supply unit 10 is detected by a comparator or the like in the power supply diagnosis unit 20 and the cutoff switch is operated to protect the subsequent units. Yes.
However, when such a method is adopted, if a short-circuit failure occurs in the cutoff switch in the power supply diagnosis unit 20, the subsequent safety diagnosis unit 30 and the safety unit 40 cannot be protected from overvoltage, and safety by the safety unit 40 or the like can be prevented. It becomes difficult to perform the function.

  Therefore, the problem to be solved by the present invention is that it has a state diagnosis function of the shut-off means for shutting off overvoltage or the like when the control power supply unit fails, and even when the failure of the control power supply unit or the shut-off means occurs repeatedly Another object of the present invention is to provide a power conversion device that can safely stop the device while protecting subsequent circuits.

In order to solve the above problems, the invention according to claim 1 is directed to a driving unit that drives a load by performing power conversion by an operation of a semiconductor switching element, and an arithmetic process for generating a control signal for controlling the semiconductor switching element. A safety unit for ensuring safety by stopping operation of the apparatus when a failure occurs, a control power supply unit that supplies a control power supply voltage to at least the arithmetic processing unit and the safety unit, and a failure of the control power supply unit In a power converter comprising: a power diagnosis unit that operates an internal shut-off means to shut off the supply of the control power voltage when an abnormality occurs in the control power voltage due to
The power supply diagnosis unit is configured to control opening and closing of the shut-off unit using a diagnosis signal output from the arithmetic processing unit and a monitoring voltage output from the power supply diagnosis unit,
The arithmetic processing unit is configured such that when the shut-off means is closed and the logic of the diagnostic signal is changed to active, a safety power supply signal corresponding to the level of the monitoring voltage is active, and the shut-off signal When the safety signal is inactive when the logic of the diagnostic signal is changed to inactive in the open state, and the failure of the shut-off means is diagnosed and the fault of the shut-off means is diagnosed In addition, the operation of the drive unit by the control signal is stopped.

  According to a second aspect of the present invention, in the power conversion device according to the first aspect, the power diagnosis unit is configured as the blocking means connected in series to a control power supply path extending from the control power source to the safety unit. A shut-off switch, a comparator that controls the shut-off switch to open and close with the monitoring voltage and a predetermined reference voltage as inputs, and a reference voltage changeover switch that switches the level of the reference voltage in accordance with the logic of the diagnostic signal. It is a thing.

  The invention according to claim 3 is the power conversion device according to claim 1 or 2, wherein the safety unit secures safety by stopping the operation of the device when a failure occurs in a place other than the control power supply unit. To do.

  The invention according to claim 4 is the power conversion device according to any one of claims 1 to 3, further comprising a safety diagnosis unit that diagnoses a state of the safety unit, wherein the control power source of the safety diagnosis unit is It is supplied from the control power supply unit.

According to the present invention, in addition to the failure diagnosis function of the control power supply unit, the function of diagnosing the state of the interruption means in the power supply diagnosis unit is also provided, so that the failure of the control power supply unit and the failure of the interruption means occurred repeatedly. Even in this case, the apparatus can be safely stopped while protecting subsequent circuits.
Further, in the present invention, as shown in FIG. 5, the circuit scale can be reduced as compared with the prior art in which the power supply voltage abnormality detection circuit and the cut-off switch are made redundant, so that space saving and cost reduction are achieved. Is possible.

It is a block diagram mainly having a supply path of a control power supply voltage in an embodiment of the present invention. It is a block diagram of the power supply diagnosis part in FIG. It is a figure which shows the diagnostic sequence in embodiment of this invention. It is a figure which shows the diagnostic sequence in embodiment of this invention. It is a block diagram of the prior art described in patent document 1. FIG. It is a block diagram which mainly made the supply path | route of the control power supply voltage in the conventional power converter device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram centering on a control power supply voltage supply path in the power conversion apparatus according to the present embodiment. 1, components having the same functions as those shown in FIG. 6 are denoted by the same reference numerals, and the configuration and functions of this embodiment will be described below with a focus on differences from FIG.

In this embodiment, the function of the power supply diagnosis unit 20A connected between the control power supply unit 10 and the safety diagnosis unit 30 and the function of the arithmetic processing unit 50A are different from those in FIG.
That is, from the power diagnosis unit 20A, the safety power signal S ₂ of the output voltage level corresponding to the (monitoring voltage) (logic level or voltage level) is input to the arithmetic processing unit 50A, is outputted from the arithmetic processing unit 50A diagnostic signal S ₁ is input to the power supply diagnostic unit 20A.
Diagnostic signals _{S 1} has, High level in accordance with the output logic of the arithmetic processing unit 50A (hereinafter, simply H that level) or Low level (hereinafter, simply referred to as L level), the safety equivalent to the feedback signal of the diagnostic signals _{S 1} power signal S ₂ becomes L level or H level according to the state of the power diagnosis unit 20A (the state of the interrupt switch 23 to be described later in other words).

FIG. 2 is a block diagram showing a configuration of the power supply diagnosis unit 20A.
In FIG. 2, an emitter and a collector of a pnp-type transistor as the cutoff switch 23 are connected in order between the control power supply unit 10 and the safety diagnosis unit 30. The collector voltage of the cutoff switch 23 is input to the non-inverting input terminal of the comparator 21 as a monitoring voltage, and the reference voltage is input to the inverting input terminal of the comparator 21. The output terminal of the comparator 21 is connected to the base of the cutoff switch 23.
The reference voltage is equal to the overvoltage setting value of the control power supply voltage (monitoring voltage) output from the control power supply unit 10, and when the control power supply unit 10 is normal, the relationship of monitoring voltage <reference voltage (overvoltage setting value) is satisfied. is there.

On the other hand, the diagnostic signal S ₁ output from the arithmetic processing unit 50A is added to the base of the npn-type transistor 22, the collector of the transistor 22 is connected to the inverting input terminal of the comparator 21, and the emitter is grounded .
The transistor 22 functions to switch the level of the reference voltage depending on whether it is turned on or off, and therefore corresponds to a reference voltage changeover switch in the claims.

Next, the operation at the time of normal operation in this embodiment and the protection operation (cut-off operation) at the time of failure of the control power supply unit 10 will be described.
When the control power supply unit 10 and the cutoff switch 23 are operating normally, the cutoff switch 23 is ON during normal operation of the power converter. At this time, the diagnostic signal S ₁ output from the arithmetic processing unit 50A because there are transistors 22 at the L level are OFF, larger reference voltage from the monitoring voltage is input to the inverting input terminal of the comparator 21. Accordingly, the output of the comparator 21 is at the L level, and the cutoff switch 23 is maintained in the ON state.

  In this state, since an appropriate power supply voltage is supplied to the safety diagnosis unit 30 and the safety unit 40, a failure other than the control power supply unit 10 (for example, a short circuit failure of a semiconductor switching element in the drive unit 60) occurs. In this case, the safety unit 40 can be operated to operate a safety function that shuts off the main power supply of the drive unit 60. Also, alarms can be displayed or transmitted to the outside as required.

When the control power supply voltage becomes an overvoltage due to the failure of the control power supply unit 10 and the monitoring voltage exceeds the reference voltage, the output of the comparator 21 is inverted to the H level and the cutoff switch 23 is turned OFF. That is, since the power supply path in the power diagnosis unit 20A is interrupted, the components of the power diagnosis unit 20A and the subsequent safety diagnosis unit 30 and safety unit 40 can be protected from overvoltage. Further, the operation of the control power supply unit 10 itself may be stopped after turning off the cutoff switch 23.
In the configuration of FIG. 2, there is no switch between the arithmetic processing unit 50A and the control power supply unit 10, and the control power supply voltage is always supplied to the arithmetic processing unit 50A. It is desirable to use a high breakdown voltage component or element.

  Next, the diagnosis operation of the power supply diagnosis unit 20A executed by the arithmetic processing unit 50A, specifically, the diagnosis operation of the cutoff switch 23 will be described with reference to FIGS. These diagrams are diagnostic sequences at the time of starting up the power conversion device. FIG. 3 shows a case where the cutoff switch 23 is normal, and FIG. 4 shows a case where the cutoff switch 23 is out of order.

  In this type of power conversion device, when the operation of the motor is stopped, there is a case where the main power supply is cut off for the purpose of energy saving and only the control power supply is supplied. For this reason, FIGS. 3 and 4 mainly show a period in which the main power supply is OFF and the control power supply is ON. During this period, since the main power is not supplied, the driving unit 60 operates the motor. On the other hand, the arithmetic processing unit 50A can periodically diagnose the state of the power supply diagnosis unit 20A.

Table 1 below shows the diagnosis operation by the arithmetic processing unit 50A and the results thereof, and the description will be continued with reference to Table 1.

First, in FIG. 3, with the cut-off switch 23 as described above is turned ON, the arithmetic processing unit 50A outputs the diagnostic signals S ₁ at the H level at time t _1. As a result, the transistor 22 in the power supply diagnosis unit 20A is turned on, so that the potential of the inverting input terminal of the comparator 21 becomes the ground potential. At this time, the output of the comparator 21 from the monitoring voltage is H level, the H level, cutoff switch 23 is turned OFF unless cutoff switch 23 are not short-circuited, safe power signal S ₂ becomes L level.
This operation is equivalent to the state 1 in Table 1, the arithmetic processing unit 50A, the diagnostic signal when S ₁ is at the H level, the safety power signal S ₂ is L level is the feedback signal from the power supply diagnostic unit 20A Therefore, it is recognized that the cutoff switch 23 is normal without a short circuit failure.

Next, the arithmetic processing unit 50A inverts the diagnosis signals _{S 1} to L level at time _{t 2} in FIG. Thereby, since the transistor 22 is turned off, the potential of the inverting input terminal of the comparator 21 becomes equal to the reference voltage. At this time, since the monitored voltage remains at L level, the output of the comparator 21 becomes L level, cutoff switch 23 is turned ON unless cutoff switch 23 is not open-circuit failure, the safety power signal S ₂ becomes H level .
This operation is equivalent to the state 2 in Table 1, the arithmetic processing unit 50A, the diagnostic signal when S ₁ is at the L level, the safety power signal S ₂ is at the H level is a feedback signal from the power supply diagnostic unit 20A Therefore, it is recognized that the cutoff switch 23 is normal without an open failure.

  As described above, if it is confirmed that the cutoff switch 23 is not short-circuited or opened, and is operating normally, then the main power is turned on and the power supply voltage is supplied to the drive unit 60. Thus, the driving of the load by the driving unit 60 becomes possible.

FIG. 4 is a diagnostic sequence in the case where the cutoff switch 23 has a short circuit failure or an open failure.
Even when the diagnostic signals S ₁ is changed to H level at time t ₁ in FIG. 4, when the safety power signal S ₂ is still H level, the cutoff switch the output of the comparator 21 even though it is H level It is assumed that 23 remains ON. This operation is equivalent to the state 3 in Table 1, the arithmetic processing unit 50A, since the diagnostic signal S ₁ and the safety power signal S ₂ are both at H level, when the shut-off switch 23 is short-circuited Can be diagnosed.
Therefore, the arithmetic processing unit 50A does not generate a PWM signal, and immediately brings the system down to a state where the power conversion device cannot be started, and performs an alarm display or the like as necessary to prompt inspection.

Further, as the time t ₂ after the 4, if it is safe power supply signal S ₂ also L level when changing the diagnostic signals S ₁ to L level, also the output of the comparator 21 is L level Regardless, it is assumed that the cutoff switch 23 remains OFF. This operation is equivalent to the state 4 in Table 1, the arithmetic processing unit 50A, since the diagnostic signal S ₁ and the safety power signal S ₂ are both at the L level, when the shut-off switch 23 is open fault Can be diagnosed.
Also in this case, the arithmetic processing unit 50A executes a process for immediately shutting down the power converter.

  Note that the sequence of FIG. 4 shows short-circuit faults and open-circuit faults of the cut-off switch 23 collectively on the same time axis for the sake of convenience. It is not supposed to happen.

  As described above, according to this embodiment, it is possible to diagnose the state of the cutoff switch 23 in the power cutoff unit 20A as well as the circuit protection operation by the overvoltage monitoring and power cutoff of the control power source unit 10. . For this reason, even when an overvoltage application due to a failure of the control power supply unit 10 and a short-circuit failure or an open-circuit failure of the cut-off switch 23 occur, it is possible to quickly detect these multiple failures and stop the apparatus safely. And a highly reliable system can be provided.

  In the above embodiment, it is assumed that the power supply voltage of the control power supply unit 10 is an overvoltage. However, even when the power supply voltage becomes an undervoltage, the circuit configuration of the power supply diagnosis unit, the diagnosis signal, and the safety power supply signal If the logic or the like is appropriately changed, it is possible to configure a power conversion device capable of diagnosing a short-circuit failure and an open-circuit failure while controlling the open / close switch 23 as described above.

  The present invention can be used for various power conversion devices such as so-called inverter devices and converter devices regardless of the form of power conversion (AC power or DC power) and the number of phases (single-phase or multi-phase).

10: Control power supply unit 20A: Power supply diagnosis unit 21: Comparator 22: Transistor 23: Cut-off switch 30: Safety diagnosis unit 40: Safety unit 50A: Arithmetic processing unit 60: Drive unit

Claims (4)

A drive unit that performs power conversion by the operation of the semiconductor switching element to drive a load, an arithmetic processing unit that generates a control signal for controlling the semiconductor switching element, and stops the operation of the apparatus when a failure occurs, thereby ensuring safety. A safety unit for securing, a control power supply unit for supplying a control power supply voltage to at least the arithmetic processing unit and the safety unit, and an internal shut-off means when a control power supply voltage abnormality occurs due to a failure of the control power supply unit In the power converter provided with a power supply diagnosis unit that cuts off the supply of the control power supply voltage,
The power supply diagnosis unit is configured to control opening and closing of the shut-off unit using a diagnosis signal output from the arithmetic processing unit and a monitoring voltage output from the power supply diagnosis unit,
The arithmetic processing unit includes:
When the shut-off means is closed and the logic of the diagnostic signal is changed to active, when the safety power signal according to the level of the monitoring voltage is active, and when the shut-off signal is open, When the safety power signal is inactive when the logic of the diagnostic signal is changed to inactive, diagnose the failure of the shut-off means ,
The power conversion device according to claim 1, wherein when the failure of the shut-off means is diagnosed, the operation of the drive unit by the control signal is stopped. In the power converter device according to claim 1,
The power diagnosis unit
A cutoff switch as the cutoff means connected in series to a control power supply path from the control power source to the safety part;
A comparator that controls opening and closing of the cutoff switch with the monitoring voltage and a predetermined reference voltage as inputs;
A reference voltage changeover switch for switching the level of the reference voltage according to the logic of the diagnostic signal;
A power conversion device comprising: In the power converter device according to claim 1 or 2,
The safety unit secures safety by stopping the operation of the device when a failure occurs in a place other than the control power supply unit. In the power converter device given in any 1 paragraph of Claims 1-3,
The power conversion device further comprising a safety diagnosis unit for diagnosing the state of the safety unit, wherein the control power supply of the safety diagnosis unit is supplied from the control power supply unit.

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