JP5258927B2 - Power converter, refrigeration air conditioning system, and control method - Google Patents

Description

  The present invention relates to a power conversion device, a refrigeration air conditioning system, and a control method.

  As variable voltage / variable frequency inverters are put into practical use, application fields of various power converters and devices related to power conversion have been developed.

  As power converters, development of applied technology for buck-boost converters is thriving. In addition, in recent years, as a new device, an element having a small current capacity but a high breakdown voltage (for example, a wide band gap semiconductor) has been actively developed. New devices have been put into practical use centering on rectifiers (see, for example, Patent Document 1 below).

JP 2006-6061 A

  However, the above-mentioned new devices have high electrical characteristics (especially recovery characteristics) and high efficiency, and devices with large current capacity have many problems for practical use such as high cost and crystal defects. Still takes time. Therefore, it is necessary to use a small-capacity element, and there is a problem that it is necessary to prevent an abnormally large current from flowing through the element.

  The present invention has been made in view of the above, and when a small-capacity element is used, a power conversion device, a refrigeration system that can ensure high efficiency and high reliability and can stop the system while preventing a failure in the event of an abnormality An object is to provide an air conditioning system and a control method.

  In order to solve the above-described problems and achieve the object, the present invention provides a power supply unit, a boosting unit, a commutation unit that forms a commutation path that is a current path outside the boosting unit, and the boosting unit. And / or a smoothing unit that smoothes the output voltage from the commutation unit, a control current detection unit that detects a current flowing through the boosting unit, and a voltage detection unit that detects a voltage across the smoothing unit. Any one of the detected current and the both-ends voltage of the abnormality determination current detection unit that detects a current flowing between the boosting unit and the smoothing unit, and the control current detection unit. A control unit that controls the boosting unit and the commutation unit, and an abnormality determination processing unit that determines whether the commutation unit is abnormal based on a current detected by the abnormality determination current detection unit; It is characterized by providing.

  According to the present invention, when a small-capacity semiconductor switch is used, there is an effect that high efficiency and high reliability are ensured, and the system can be stopped while preventing a failure at the time of abnormality.

FIG. 1 is a diagram illustrating a configuration example of the power conversion device according to the first embodiment. FIG. 2A is a diagram illustrating a current path in each mode. FIG. 2-2 is a diagram illustrating a current path in each mode. FIG. 2-3 is a diagram illustrating a current path in each mode. FIG. 2-4 is a diagram illustrating a current path in each mode. FIG. 3 is a diagram illustrating an example of each operation waveform when commutation control is disabled. FIG. 4 is a diagram illustrating a recovery current when commutation control is disabled. FIG. 5 is a diagram illustrating an example of each operation waveform when commutation control is enabled. FIG. 6A is a diagram illustrating a configuration example of a recovery current detection unit that detects a recovery current. FIG. 6B is a diagram of another configuration example of the recovery current detection unit. FIG. 7A is a diagram illustrating an example of each signal in the abnormality determination process when the configuration example of FIG. 6A is used. FIG. 7B is a diagram of an example of each signal in the abnormality determination process when the configuration example of FIG. 6-2 is used. FIG. 8-1 is a flowchart illustrating an example of a processing procedure of abnormality determination processing according to the first embodiment. FIG. 8-2 is a flowchart illustrating an example of a processing procedure of abnormality determination processing when the recovery current detection unit illustrated in FIG. 6-2 is used. FIG. 9 is a diagram illustrating an example of a circuit configuration of the commutation unit when the switch is a MOSFET. FIG. 10 is a diagram illustrating an example of the commutation control signal, the gate voltage of the switch, and the drain-source voltage. FIG. 11 is a diagram illustrating an example of a commutation control signal, a gate voltage of a switch, and a drain-source voltage when a short-circuit failure occurs in a drain-source voltage. FIG. 12A is a diagram of a configuration example of a drain-source voltage detection unit. FIG. 12B is a diagram of another configuration example of the drain-source voltage detection unit. FIG. 13 is a flowchart illustrating an example of a processing procedure of abnormality determination processing for detecting abnormality by the drain-source voltage of the switch of the commutation unit. FIG. 14 is a diagram illustrating a configuration example of the power conversion device according to the second embodiment. FIG. 15 is a diagram illustrating a configuration example of the power conversion device according to the third embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments of a power conversion device, a refrigeration / air conditioning system, and a control method for a power conversion device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a power conversion device according to the present invention. The power conversion device of this embodiment illustrated in FIG. 1 is a power conversion device that can perform power conversion with high efficiency. The power converter of this Embodiment can be used as a power converter built in a refrigerating and air-conditioning system, for example.

  As shown in FIG. 1, the power conversion device according to the present embodiment is smoothed by the power supply unit 1, the booster 2, the smoothing unit 3 that smoothes the output voltage of the booster 2, and the smoothing unit 3. A voltage detection unit 5 that detects a voltage, and a commutation unit 4 that commutates current flowing in the boosting unit 2 to different paths at a necessary timing. In addition, the power conversion device according to the present embodiment converts a current detection element 10 that detects a current flowing through a connection line between the power supply unit 1 and the load 9 and a signal obtained from the current detection element 10 into a controllable amount. A current detection unit 11; a current detection element 12 that detects a current flowing through a switch (boost switch) 22 in the boosting unit 2; and a current detection unit 13 that converts a signal obtained from the current detection element 12 into a controllable amount. The voltage detection unit (abnormality determination voltage detection unit) 46 for detecting the voltage applied to the switch (commutation switch) 44 in the commutation unit 4, the voltage value obtained from the voltage detection unit 5, and the voltage detection unit 46 A control unit 6 that controls the boosting unit 2 and the commutation unit 4 using the voltage value obtained, the current value obtained from the current detection unit 10 and the current value obtained from the current detection unit 13, and the boosting generated by the control unit 6 Drive signal of part 2 A driving signal transmission unit 7 that reaches, a commutation signal transmission unit 8 that transmits a commutation signal of the commutation unit 4 generated by the control unit 6, a load 9 that is connected to the subsequent stage of the boosting unit 2 and the smoothing unit 3, Is provided.

  The boosting unit 2 according to the present embodiment includes, for example, a reactor 21 connected to the positive side or the negative side of the power supply unit 1, a switch 22 and a rectifier (backflow prevention unit) 23 connected to the subsequent stage. . As shown in FIG. 1, a connection point between the connection line between the power supply unit 1 and the load 9 and the switch 22 is a point A after the reactor 21. Further, point B is between the rectifier 23 (anode side) on the connection line between the reactor 21 and the load 9 and the point A, and point C is smooth with the rectifier 23 (cathode side) on the connection line between the reactor 21 and the load 9. Between part 3. As the switch 22, for example, an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor (MOS) -field effect transistor (FET), or the like is used.

  The current detection element 10 according to the present embodiment has a power supply section when the connection point between the power supply section 1 and the switch 22 on the connection line below the load 9 (the side to which the reactor 21 is not connected) is D point. A current flowing between point 1 and point D is detected. As the current detection element 10, for example, an ACCT (current transformer), a DCCT (utilization of a Hall element / Hall IC, etc.), etc. can be used. In addition, the current detection unit 11 includes an amplification circuit, a level shift circuit, a filter circuit, and the like so that the value detected by the current detection element 10 can be captured as a value (Idc) that can be processed in the control unit 6. Is done. The control unit 6 controls the switch 22 using Idc. The current detection unit 11 may be omitted as appropriate when the control unit 6 has the function. When applying an application that does not perform current control, the current detection element 10 and the current detection unit 11 may be omitted as appropriate.

  The control unit 6 controls the opening / closing of the switch 22 using both or either one of the both-end voltage Vdc of the smoothing unit 3 detected by the voltage detection unit 5 and the Idc output from the current detection unit 11. When the control unit 6 does not use the both-end voltage Vdc, the voltage detection unit 5 may not be provided.

  For example, an ACCT or a shunt resistor can be used for the current detection element 12 of the present embodiment. Further, the current detection unit 13 is an amplification circuit, a level shift circuit, a filter circuit, or the like for taking in the value detected by the current detection element 12 as an appropriate value (Ip) that can be processed in the control means 6. Composed. Similarly to the current detection unit 11, the current detection unit 13 may be omitted as appropriate when the control unit 6 has the function.

  In addition, since the electric current input into the control part 6 is produced | generated by the electric current detection element 12 and the electric current detection part 13, the electric current detection element 12 and the electric current detection part 13 can be considered as an electric current detection part in a broad sense. Similarly, the current detection element 10 and the current detection unit 11 can be considered as a current detection unit in a broad sense. The current detection element 12 and the current detection unit 13 function as an abnormality determination current detection unit in order to measure a current used for abnormality determination processing as will be described later, and the current detection element 10 and the current detection unit 11. Has a function as a control current detector for controlling the switch 22.

  The open / closed state of the switch 22 is operated by the drive signal SA output from the drive signal transmission unit 7. The drive signal transmission unit 7 converts the drive control signal sa that controls opening and closing of the switch 22 generated by the control device 6 into a drive signal SA. The drive signal transmission unit 7 includes, for example, a buffer, a logic IC, a level shift circuit, and the like. However, when the control device 6 has a function of converting the drive control signal sa into the drive signal SA, the drive signal transmission unit 7 may be omitted as appropriate. In that case, the opening and closing of the switch 22 is directly operated by the drive signal SA output from the control device 6.

  The commutation unit 4 includes a transformer 41, a rectifier (commutation rectifier) 42 connected in series with the transformer 41, and a transformer drive circuit 43 that drives the transformer 41. In FIG. 1, the polarity of the primary side winding and the secondary side winding of the transformer 41 is the same. The secondary winding of the transformer 41 is connected in series with the rectifier 42. Further, the rectifier 42 is connected in parallel with the rectifier 23 of the booster 2.

  The transformer drive circuit 43 includes, for example, a power supply 45 for driving the transformer 41 and a switch 44 that switches whether to connect the transformer 41 and the power supply 45. In consideration of noise countermeasures and failure protection, if necessary, a limiting resistor, a high-frequency capacitor, a snubber circuit, a protection circuit, etc. may be inserted in the path of the primary side winding of the power supply 45, switch 44, and transformer 41. . In this example, the transformer 41 is not provided with a reset winding for resetting the excitation current. However, if necessary, a reset winding is added to the primary winding, and a rectifier or the like is further provided to provide excitation energy. High efficiency can be achieved by regeneration on the power supply side.

  The open / closed state of the switch 44 is operated by the commutation signal SB output from the commutation signal transmission unit 8. The commutation signal transmission unit 8 converts the commutation control signal sb that is generated by the control device 6 to control opening and closing of the switch 44 into the commutation signal SB. The commutation signal transmission unit 8 is configured by, for example, a buffer, a logic IC, a level shift circuit, and the like, similarly to the drive signal transmission unit 7. However, when the control device 6 has a function of converting the commutation control signal sb into the commutation signal SB, the commutation signal transmission unit 8 may be omitted as appropriate. In that case, the opening and closing of the switch 44 is directly operated by the drive signal SA output from the control device 6.

  The voltage detection units 5 and 46 are configured by a level shift circuit using a voltage dividing resistor. The voltage detection units 5 and 46 may add an analog / digital converter so that the control unit 6 can calculate the detected signal as necessary.

  The control unit 6 is configured by a microcomputer, an arithmetic device such as a digital signal processor, or a device having the same function therein.

  Next, with regard to the power conversion device according to the present embodiment shown in FIG. 1, a flow path when power is supplied from the power supply unit 1 to the load 9 will be described. The operation of the power conversion device of the present embodiment is obtained by adding a commutation operation of a rectifier to a boost chopper. Therefore, there are four types of combinations of the open / close states of the switch 22 and the switch 44, and there are a total of four operation modes. 2A to 2D are diagrams illustrating current paths in the respective modes.

  First, consider a mode (mode (1)) in which the switch 22 is on and the switch 44 is off. Usually, an element having a good recovery characteristic is used for the rectifier 42, and an element having a lower forward voltage than the rectifier 42 is used for the rectifier 23. Further, since the winding of the transformer 41 is an inductor component, no current flows when no exciting current is passed. Accordingly, in the mode (1) in which the switch 44 is OFF, no current flows into the path of the commutation unit 4. Since the switch 22 is on, energy can be stored in the reactor 21 through the current path R shown in FIG.

  Next, consider a mode (mode (2)) in which the switch 22 is off and the switch 44 is off. Also in this case, the switch 44 is off and no current flows into the path of the commutation unit 4. Further, since the switch 22 is off, the energy of the reactor 21 can be supplied to the load side through the current path R shown in FIG.

  Next, consider a mode (mode (3)) in which the switch 22 is on and the switch 44 is on. In this case, the switch 44 is on, but the switch 22 is also on at the same time, and since the impedance on the power supply unit 1 side is low, almost no current flows in the path of the commutation unit 4, and FIG. Energy can be stored in the reactor 21 through the current path R shown. In mode (3), there may be a momentary flow into the path of the commutation unit 4 due to a transmission delay of the commutation signal SB, but this is not a problem in use.

  Next, consider a mode (mode (4)) in which the switch 22 is off and the switch 44 is on. In this case, the switch 22 is off, and a current flows into the load 9 via the rectifier 23 (current path R1 in FIG. 2-4). Further, since the switch 44 is also turned on, the transformer 41 is excited and current flows into the path of the commutation unit 4 as shown in FIG. 2-4 (current path R2). And after a fixed time passes, it will commutate completely to the rectifier 42 side.

From the above, although the commutation operation occurs in the mode (4) (the switch 22 is OFF and the switch 44 is ON), the energy storage operation by opening and closing the switch 22 in the power conversion device of the present embodiment It follows the boost chopper. Therefore, when the switch 22 repeatedly performs switching at the on time T _on and the off time T _off , an average voltage E _C represented by the following expression (1) is obtained at the point _C. Here, for simplification, the voltage of the power supply unit 1 is assumed to be a DC power supply E ₁ .
E _C = ((T _on + T _off ) / T _off ) · E ₁ (1)

  FIG. 3 is a diagram illustrating an example of each operation waveform when commutation control is disabled (the commutation unit 4 is not provided). In FIG. 3, the waveforms of the drive control signal sa output from the control unit 6 for the boosting unit 2, the current I1 flowing through the reactor 21, the current I2 flowing through the switch 22, and the current I3 flowing between the points A and B are sequentially shown from the top. Show. In FIG. 3, the drive control signal sa has a binary value of High and Low, and indicates that the switch 22 is turned on (closed) in the case of High. As described above, no current flows into the path of the commutation unit 4 in this case. In this case, as shown in FIG. 4, the recovery current Ir flows through the path indicated by the arrow in the interval until the reverse recovery operation of the rectifier 23 is completed at the timing when the switch 22 is turned on.

  FIG. 5 is a diagram illustrating an example of each operation waveform when commutation control is enabled. In FIG. 5, the drive control signal sa, the commutation control signal sb, the current I1, the current I2, the current I3, the current I4 flowing through the rectifier 23, and the secondary side winding of the transformer 41 output from the control unit 6 to the boosting unit 2. The waveforms of the current I5 flowing through the rectifier 42 are shown in order from the top. In FIG. 5, the drive control signal sa and the commutation control signal sb are binary values of High and Low, and indicate that the switch 22 and the switch 44 are turned on (closed) in the case of High.

  Each waveform in FIG. 5 is an example after a sufficient time has elapsed after the on-time and off-time of the drive control signal sa are controlled so that the load 9 and the output voltage Vdc become a constant output after the power supply unit 1 is turned on. Is shown. FIG. 5 illustrates an example in which the ratio (duty) of the on time and the off time of the drive control signal sa is substantially constant. In FIG. 5, the ratio of the on time and the off time is assumed to be constant assuming that the power supply unit 1 is a DC power supply. However, the power supply unit 1 is an AC power supply and the DC side voltage is proportionally integrated. For example, when a constant control is performed using, for example, the duty ratio may be adjusted by changing the ratio (duty) of the on time and the off time of the drive control signal sa.

In FIG. 5, the commutation control signal sb shows a waveform example when the pulse width is fixed. An example in which the pulse width of the commutation control signal sb is variable will be described later. I1 is branched at a point A in FIG. 1 and then is divided into a current I2 flowing through the switch 22 and a current I3 flowing toward the rectifier 23, and therefore can be expressed by the following equation (2).
I1 = I2 + I3 (2)

After branching at point B, I3 is shunted into a current I4 flowing through the rectifier 23, a secondary winding of the transformer 41, and a current I5 flowing toward the rectifier 42, and therefore can be expressed by the following equation (3).
I3 = I4 + I5 (3)

  When the driving signal sa is turned on while a forward current is flowing through the rectifier 23, the point A and the point D become conductive, so the point B potential is substantially equal to the point D potential (the points A and B are the same potential). ). For example, if an insulated gate bipolar transistor (IGBT), a field effect transistor (MOSFET), or the like is used as the switch 22, the on-voltage of the element of the switch 22 becomes a potential difference between the point B and the point D (that is, the potential at the point B is a power source). It becomes substantially equal to the negative potential of the supply unit 1). On the other hand, the C point potential is substantially held in the charged potential state by the smoothing unit 3. Therefore, at this time, the potential difference reverse bias between the point C and the point B is applied to the rectifier 23, and the rectifier 23 shifts to an off operation.

  Normally, a pn junction diode is used for the rectifier 23, but a short-circuit current (hereinafter referred to as a recovery current) flows through the path from the rectifier 23 to the switch 22 until the rectifier 23 is reversely recovered. Therefore, in order to prevent an increase in circuit loss due to the recovery current, the commutation control signal sb applied to the commutation unit 4 is turned on immediately before the drive control signal sa is turned on, and flows to the rectifier 23 via the transformer 41. Current is commutated to the rectifier 42.

  A current flows through the rectifier 42 only immediately before the switch 22 is turned on. That is, the flow section is limited. Therefore, although it is necessary to be an element that can withstand repeated spire currents, an element having a smaller current capacity (rated) than the rectifier 23 can be used. In general, a rectifier tends to have a smaller amount of stored carriers in an element having a smaller current capacity than an element having a large current capacity. Therefore, as the current capacity decreases, the time until reverse recovery can be shortened, and as a result, the recovery current decreases. Also, the recovery current decreases as the applied reverse bias voltage decreases. As described above, the recovery current can be reduced by adding the commutation operation from the rectifier 23 to the rectifier 42 using the commutation control signal sb.

  It is possible to further increase the efficiency by using a wide band gap semiconductor such as SiC, GaN or diamond for the rectifier 42.

  In the above, the method of performing the commutation operation by the control signal for operating the opening and closing of the switch 22 and the switch 44 has been described. Until now, there have been almost no technically disclosed examples of a failure detection method and a subsequent coping method when the commutation unit 4 causes a circuit failure or an operation failure. On the other hand, when a wide band gap semiconductor is used for the rectifier 42, a large-capacity element is expensive, and a small-capacity element is often used. In normal operation, the design is made so as not to exceed the capacity of the elements of the rectifier 42. However, it is necessary to protect the capacity of the elements of the rectifier 42 so as not to exceed the capacity of the elements of the rectifier 42. Detection is important.

  In the present embodiment, a failure detection method when a specific component in the commutation unit 4 has an open failure or a short failure will be described. First, when a specific component (for example, the switch 44 (between the drain and source of the element in the case of a MOSFET), the rectifier 42, the primary winding or the secondary winding of the transformer 41, etc.) in the commutation unit 4 has an open failure. The detection method and the subsequent countermeasures will be described.

The recovery current is generated due to the reverse recovery operation of the rectifier 23 or the rectifier 42. Therefore, the current is observed in the following path at the ON timing of the switch 22 (the timing when the switch 22 is turned ON) after the current flows through one of the rectifiers 23 and 42.
(1) Path of “smoothing part 3 → rectifier 23 → switch 22 → current detection element 12 → smoothing part 3” (2) “smoothing part 3 → rectifier 42 → secondary winding of transformer 41 → switch 22 → current detection Path from element 12 to smoothing unit 3 "

  Therefore, the recovery current can be observed by inserting the current detection element into the paths (1) and (2). Further, since the boosting switch 22 is included in both paths (1) and (2), the current I2 flowing through the boosting switch 22 is detected to recover both the paths (1) and (2). The magnitude of the current can be observed. That is, the current detection element 12 can detect the recovery current. However, the insertion position of the current detection element is not limited to this location, and may be arranged so that a desired recovery current can be detected according to the configuration.

  Focusing on the current I2, it can be confirmed that the recovery current (at the rise of the waveform) is reduced when the commutation control is enabled (FIG. 5) compared to when the commutation control is disabled (FIG. 3). However, when the switch 44 for driving the transformer 41 in the commutation unit 4 fails, the commutation control effect cannot be obtained. Therefore, even when the commutation control is valid, the waveform shape is the same as that in FIG. Become.

  If operation is continued in this state, depending on the specifications of the switch 22, switching loss increases (element temperature also increases), and system efficiency may deteriorate. In addition, generated noise may increase. If a system is constructed assuming these effects, the cost will increase as a result.

  Therefore, it is important to observe the recovery current (rising edge of I2) using the current detection element 12 and the current detection unit 13 of FIG. 1 and determine whether the commutation unit 4 is normal or abnormal based on this current value. And in this Embodiment, the control part 6 performs this determination (abnormality determination process). In this embodiment, an example in which the control unit 6 performs the recovery current detection process and the abnormality determination process will be described. However, as a block different from the control unit 6, the recovery current detection process that performs the recovery current detection process is performed. You may make it provide a part.

  FIG. 6A is a diagram illustrating a configuration example of a recovery current detection unit that detects a recovery current. FIG. 6B is a diagram of another configuration example of the recovery current detection unit. FIG. 7A is a diagram illustrating an example of each signal in the abnormality determination process when the configuration example of FIG. 6A is used. FIG. 7B is a diagram of an example of each signal in the abnormality determination process when the configuration example of FIG. 6-2 is used.

  First, the case where the configuration example of FIG. 6A is used will be described. In the recovery current detection unit shown in FIG. 6A, the current I2 is first taken in from the current detection element 12 as an analog amount Ip (continuous amount) that can be input to the control unit 6 via the current detection unit 13, and then sampled and held. The detection value Ip1 is converted through the circuit 101 and the A / D (Analog / Digital) converter 102. Specifically, the hold circuit 101 holds the value of Ip captured at every predetermined update timing (hold timing). The A / D converter 102 converts Ip into a detection value Ip1 that is a discrete value.

  FIG. 7A shows an example of the hold timing, and the black circle of the detection value Ip1 in FIG. 7A shows the held detection value. FIG. 7-1 is an example, and the hold timing may be performed at the timing when the switch 22 of the boosting unit 2 is turned on (the timing when the signal sa is turned on) or immediately after that a predetermined time elapses. It is not limited to. Although the hold interval differs for each system, it may be performed at a predetermined interval according to each system. For example, when current control or the like is performed and the on-duty of the switch 22 is variable every time, the hold circuit 101 performs a hold operation in consideration of a predetermined delay time from the on-timing of the switch 22 as a trigger. Then, after the A / D conversion is performed by the A / D converter 102, the next detection timing (ON timing of the switch 22) may be set.

  When the recovery current detection unit is implemented by hardware external to the control unit 6, a filter circuit is provided in the input stage or output stage of the hold circuit 101 and the A / D converter 102 in consideration of noise superimposed on the wiring. For example, a noise removing unit such as the above may be added.

  According to the method described above, since the rising timing of the drive signal sa of the boosting unit 2 is set as the hold timing, the recovery current can be detected relatively easily. Further, from the rise timing of sa, it is possible to hold at a timing after providing a predetermined delay time in consideration of the time during which the switch 22 is actually conducted. Therefore, the S / N ratio of the detected current value Ip1 can be increased. This can improve the accuracy of the abnormality determination described later.

  The abnormality determination process is performed using the detection value Ip1 and a predetermined threshold value determined in advance through experiments or the like. In FIG. 7A, this threshold is indicated as Y as an example.

  FIG. 7A illustrates an example in which the recovery current is not suppressed due to a failure in the commutation unit 4 or the like. As shown in FIG. 7A, depending on the hold timing or the like, there may actually be a case where the detection value Ip1 falls below the threshold value even if a large recovery current is generated (even if the recovery current is not suppressed). (For example, the fourth black circle from the left of the detection value Ip1 in FIG. 7A). Therefore, rather than determining an abnormality based on whether or not the threshold has been exceeded by a single comparison (comparison between the detection value Ip1 and the threshold), the determination is made in consideration of the number of times the threshold has been exceeded, the time for which the abnormality is to be determined, and the like Doing so can increase the reliability.

  FIG. 8A is a flowchart illustrating an example of a processing procedure of abnormality determination processing according to the present embodiment. First, the control unit 6 sets the determination time to a predetermined value ts, and sets the counter value N to N = 0 (initial value). Then, it is determined whether or not the elapsed time from the start of processing is less than ts (step S11). When the elapsed time from the start of the process is equal to or longer than ts (No in step S11), the process ends. Although an example in which the control unit 6 performs the abnormality determination process will be described below, an abnormality determination processing unit may be provided separately from the control unit 6 so that the abnormality determination processing unit performs the abnormality determination process. In that case, the recovery current detection unit is included in the abnormality determination processing unit.

  When the elapsed time from the start of processing is less than ts (step S11 Yes), the recovery current detection unit obtains a detection value Ip1 based on the current Ip (step S12). Next, it is determined whether or not the detected value Ip1 is greater than or equal to the threshold Y (that is, a recovery current is generated) (step S13). If the detected value Ip1 is less than the threshold Y (step S13 No), step Return to S11.

  If the detected value Ip1 is greater than or equal to the threshold Y (step S13 Yes), the counter N is incremented by 1 (step S14), and it is determined whether N is greater than or equal to the predetermined value Z (step S15). When N is greater than or equal to a predetermined value Z (step S15 Yes), it is determined that the circuit / operation of the commutation unit 4 is abnormal (step S16), a predetermined abnormality process is performed (step S17), and the process is terminated. To do.

  The abnormality process in step S17 indicates a protective operation of the power conversion device. Specifically, for example, one or more of the step-up operation stop of the step-up unit 2, the commutation operation stop of the commutation unit 4, or the power supply stop to the commutation unit 4 is performed.

  If it is determined in step S15 that N is less than the predetermined value Z (No in step S15), the process returns to step S11.

  As described above, in the present embodiment, when the number of times the detected value Ip1 becomes equal to or greater than the threshold Y within the period ts is equal to or greater than Z, it is determined that the circuit / operation abnormality of the commutation unit 4 is abnormal. By performing the processing, the system can be protected with high reliability when a circuit / operation failure occurs in the commutation unit 4 or the like.

  For example, when the recovery current is very steep, the recovery current detection unit may be realized by the configuration shown in FIG.

  In the configuration example of FIG. 6B, the recovery current detection unit includes a filter circuit 103 and a comparator 104. FIG. 7-2 shows an example of the waveform of each signal in the process.

  In the configuration example of FIG. 6B, Ip obtained by the current detection element 12 and the current detection unit 13 passes through the filter circuit 103. The filter circuit 103 is composed of a low-pass filter (CR filter) or the like for removing high-frequency noise or the like. In this embodiment, noise is removed by the filter circuit 103 to prevent erroneous detection.

  The signal Ip ′ after passing through the filter circuit 103 is input to the comparator 104. The comparator 104 compares the signal Ip ′ with the threshold Y, and outputs a detection value Ip1 that is High output (abnormal) when the signal Ip ′ is less than Y, and Low output (normal) when the signal Ip ′ is Y or more. Note that the threshold Y is set to a value obtained by an experiment in advance.

  In this case, the detection value Ip1 that is the output of the comparator 104 is binary (High, Low), so A / D conversion or the like is unnecessary, and the control unit 6 makes an abnormality determination based on the detection signal Ip1. What is necessary is just to have the function to perform.

  When the recovery current detection unit illustrated in FIG. 6B is provided outside the control unit 6, the threshold Y is set by setting the power source of the control unit 6 through a voltage dividing resistor. If noise due to the wiring between the control unit 6 and the comparator 104 cannot be ignored, a countermeasure may be taken by adding a filter circuit or the like between the comparator 104 and the control unit 6.

  Even when the recovery current detection unit having the configuration of FIG. 6-2 is used, the control unit 6 may determine that there is an abnormality by only one determination (one time Ip1 becomes High), or FIG. As shown in FIG. 1, the determination may be performed in consideration of the number of times of showing an abnormal value, the time to be determined (elapsed time), and the like.

  FIG. 8-2 is a flowchart illustrating an example of a processing procedure of abnormality determination processing when the recovery current detection unit illustrated in FIG. 6-2 is used. Step S11 is similar to the example of FIG. When it is determined in step S11 that the elapsed time is less than ts (Yes in step S11), in step S12a, the recovery current detection unit of the control unit 6 obtains the binary detection value Ip1 as described above (step S12a). Then, the recovery current detection unit of the control unit 6 determines whether Ip1 is Hi (High) (step S13a). If it is Hi (step S13a Yes), the process proceeds to step S14. (Step S13a No) returns to Step S11. Steps S15 to S17 are the same as in the example of FIG.

  In the present embodiment, the current detection element 12 is inserted between the switch 22 of the boosting unit 2 and the negative electrode of the smoothing unit 3, and the current flowing through the switch 2 (current for detecting the recovery current) is measured. However, the current measurement location is not limited to this. For example, a current detection element may be inserted between the switch 22 of the booster 2 and the rectifier 23 or between the positive electrode of the smoothing unit 3 and the rectifier 23. Also, a plurality of locations may be measured, and the recovery current may be detected based on the measurement results at the locations.

  Next, an abnormality detection method due to a short fault according to the present embodiment and a target method thereof will be described. Components that may cause a short-circuit failure include a transformer 41, a rectifier 42, a switch 44 in the commutation unit 4, and the like, but a major failure mode generated by adding the commutation unit 4 is a switch. 44 short faults (for example, in the case of MOSFET, the short circuit between the drain and the source of the element). Therefore, here, a detection method of this failure mode and a coping method will be described.

  FIG. 9 is a diagram illustrating an example of a circuit configuration of the commutation unit 4 when the switch 44 is a MOSFET. In the present embodiment, the voltage detection unit 46 detects the drain-source voltage of the switch 44, and the control unit 6 takes in the detected value and makes an abnormality determination.

  FIG. 10 is a diagram illustrating an example of the commutation control signal sb, the gate voltage of the switch 44, and the drain-source voltage. Normally, when the commutation control signal sb transitions from off to on, the drain-source voltage Va of the switch 44 becomes Lo (Low) in response to the rise of the gate voltage of the switch 44, as shown in FIG. The switch 44 is turned on.

  However, when the drain-source voltage of the switch 44 is short-circuited, Lo is always indicated. FIG. 11 is a diagram illustrating an example of the commutation control signal sb, the gate voltage of the switch 44, and the drain-source voltage when the drain-source voltage of the switch 44 is short-circuited.

  As for the abnormality detection due to the short-circuit failure of the drain-source voltage of the switch 44, the control unit 6 uses, for example, a drain-source voltage detection unit configured as shown in FIG. Realize by providing. A drain-source voltage detector may be provided separately from the controller 6.

  The drain-source voltage detection unit takes in the drain-source voltage of the switch 44 through the voltage unit 46 as an analog amount of drain-source voltage Va, and passes through the sample hold circuit 105 and the A / D converter 106. And converted into a detection voltage Va1 which is a discrete value. Specifically, the hold circuit 105 holds the value of Va taken in every predetermined update timing (hold timing). The A / D converter 106 converts the drain-source voltage Va into a detection voltage Va1 that is a discrete value.

  A black circle shown in the detection voltage Va1 in FIGS. 10 and 11 shows an example of the hold timing (the black circle indicates the detection voltage held).

  This hold timing may be performed at an arbitrary timing in the ON section and the OFF section of the switch 44 of the commutation unit 4 (however, the state transition timing is excluded). The hold interval differs depending on the system, and may be performed at the switching cycle interval of the switch 44 or the switching number cycle interval. FIG. 11 shows an example of a short circuit failure of the switch 44. However, since Va1 maintains the Hi state in the case of an open failure, an abnormality can be detected by performing level determination based on a threshold Y determined in advance through experiments or the like. is there.

  FIG. 12B is a diagram of another configuration example of the drain-source voltage detection unit. The description is omitted because it is the same as in FIG. 6-1, but as in FIG. 6-1, by using the filter circuit 107 and the comparator 108 to output a binary detection value Va1, the same as in current detection. Abnormality detection of the drain-source voltage can be performed.

  Also, in the case of voltage detection (drain-source voltage of the switch 44), similarly to the detection of the recovery current, the determination is performed in consideration of the number of times an abnormal value is displayed, the time for performing the abnormality determination, and the like. More reliability can be improved.

  FIG. 13 is a flowchart illustrating an example of a processing procedure of an abnormality determination process for detecting an abnormality based on the drain-source voltage of the switch 44 of the commutation unit 4. First, the control unit 6 sets the determination time to a predetermined value ts, and sets the counter value N to N = 0. And step S11 is implemented like FIG. If it is determined in step S11 that the elapsed time is less than ts (step S11 Yes), whether or not the permission flag FA is a value (for example, 1) indicating that holding (or capturing) is permitted. Is determined (step S21). The permission flag FA permits the hold circuit 105 to hold the drain-source voltage Va when the drain-source voltage detection unit of the configuration example of FIG. 12-1 is used (or permits the detection value Va1 to be captured). It is a flag indicating whether or not to do.

  The permission flag FA is set to an initial value that does not permit hold (or capture) (here, for example, 0). When hold (or capture) is permitted, hold (or capture) capture is permitted. The value shown is set (here, for example, 1). For example, for the initial value, a value that does not permit hold (or capture) is set as the permission flag FA, and a value that permits hold (or capture) for each hold time interval (or capture time interval) is set. In addition, setting to a value that does not permit hold (or capture) is repeated. In other words, hold (or capture) is permitted at every hold time interval (or capture time interval).

  When the permission flag FA is not a value indicating that holding (or capturing) is permitted (No at Step S21), Step S21 is repeated. When the permission flag FA is a value indicating that holding (or capturing) is permitted (step S21 Yes), voltage detection # 1 is performed (step S22).

  In voltage detection # 1, the drain-source voltage detector outputs the input drain-source voltage Va as a detection value Va1. Here, the detection value Va1 obtained by the voltage detection # 1 is α, and the control unit 6 holds this α.

  Next, the controller 6 determines whether or not the state of the commutation control signal sb has been turned from on to off or from off to on (step S23). If not reversed (No at step S23), step S23 is repeated. When reversed (Yes in step S23), it is determined whether or not a predetermined time has elapsed using the permission flag FB (step S24). Like the permission flag FA, the permission flag FB is a flag indicating whether or not hold (or capture) is permitted. The initial value is a value that does not permit hold (or capture) (here, 0), Assume that the value (here, 1) is set to permit holding (or capturing) when a predetermined time has elapsed after the end of step 23. When the predetermined time has not elapsed, that is, when the permission flag FB is 0 (No in step S24), step S24 is repeated.

  When the predetermined time has elapsed, that is, when the permission flag FB is 1 (Yes in step S24), voltage detection # 2 is performed (step S25). The voltage detection # 2 is the same as the voltage detection # 1 in step S22. Here, the detection value Va1 is β, and the control unit 6 holds β.

  Next, the control unit 6 determines whether to add the counter N (count determination) (step S26). As the count determination, for example, it is determined whether “the values of α and β are both equal to or larger than a predetermined value Y set in advance” or “the values of α and β are both less than Y”. If “the values of α and β are both equal to or larger than the predetermined value Y1 set in advance”, it is determined that the counter N is added because there is a possibility of an open failure of the switch 44, and “both values of α and β are It is determined that the counter N is added because there is a possibility that the switch 44 is short-circuited when the value is equal to or greater than a predetermined value Y set in advance or when both the values of α and β are less than Y. In other cases, it is determined that the counter N is not added.

  If it is determined in step S26 that the counter N is to be added (step S26 Yes), the process proceeds to step S14. Steps S14 to S17 are the same as in FIG. If it is determined in step S26 that the counter N is not added (No in step S26), the process returns to step S11.

  Also, as shown in FIG. 12B, when the detection value Va1 is output as a binary value, for example, in the count determination in step S26 described above, for example, “the values of α and β are both Hi” ( The determination may be made according to whether the drain-source of the switch 44 is open failure) or “the values of α and β both indicate Lo” (when the drain-source of the switch 44 is short-circuit failure).

  As described above, in this embodiment, when the commutation unit 4 is provided to prevent an increase in circuit loss due to the recovery current, the control unit 6 detects the recovery current flowing through the boosting switch 22 and detects the detected recovery. Based on at least one of the current and the drain-source voltage of the switch 44, the circuit failure or malfunction of the commutation unit 4 is determined. For this reason, using a small-capacity semiconductor switch, high efficiency and high reliability can be ensured, and the system can be stopped while preventing a failure in the event of an abnormality. In addition, when an abnormal value is detected more than a predetermined number of times within a predetermined time at the time of determination, it is determined as abnormal (circuit failure or malfunction of the commutation unit 4), thereby further improving the reliability of abnormality determination. Can do.

Embodiment 2. FIG.
FIG. 14: is a figure which shows the structural example of Embodiment 2 of the power converter device concerning this invention. The power conversion device according to the present embodiment includes a power supply unit 1a instead of the power supply unit 1 according to the first embodiment, and detects a zero-cross detection unit signal of the voltage zero cross detection unit signal of the AC power supply 201 in the power supply unit 1a. Except adding 100, it is the same as that of the power converter device of Embodiment 1. FIG. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The power supply unit 1 a includes a single-layer AC power supply 201 and a rectifier 202 that rectifies the AC power supply 201. Here, the rectifier 202 has a bridge connection configuration. The zero cross detection unit 100 detects the voltage zero cross signal ZC of the AC power supply 201 and inputs it to the control unit 6. Based on the voltage zero cross signal ZC, the control device 6 generates a drive control signal sa and the like so as to generate a current signal synchronized with the power supply voltage of the AC power supply 201.

  The operations of the present embodiment other than those described above are the same as those of the first embodiment. Thus, also when using the power supply part 1a comprised by the alternating current power supply 201 and the rectifier 202, the abnormality determination process of Embodiment 1 can be implemented and the effect similar to Embodiment 1 can be acquired. it can.

Embodiment 3 FIG.
FIG. 15: is a figure which shows the structural example of Embodiment 3 of the power converter device concerning this invention. The power conversion device according to the present embodiment is the same as the power conversion device according to the first embodiment, except that the power supply unit 1b is provided instead of the power supply unit 1 according to the first embodiment. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The power supply unit 1 b includes a three-layer AC power supply 203 and a rectifier 204 that rectifies the AC power supply 203. Here, the rectifier 204 has a bridge connection configuration.

  The operations of the present embodiment other than those described above are the same as those of the first embodiment. As described above, even when the power supply unit 1b including the three-layer AC power supply 203 and the rectifier 204 is used, the abnormality determination process of the first embodiment can be performed, and the same effect as the first embodiment can be obtained. Can be obtained.

The abnormality determination process according to the present invention is not limited to the configuration described in the first to third embodiments,
The various converters having the step-up / step-down function can be applied to any configuration as long as it has a commutation portion (rectifier) for preventing backflow.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Power supply part 2 Boosting part 3 Smoothing part 4 Commutation part 5,46 Voltage detection part 6 Control part 7 Drive signal transmission part 8 Commutation signal transmission part 9 Load 10,12 Current detection element 11,13 Current Detection unit 21 Reactor 22, 44 Switch 23, 42, 202, 204 Rectifier 41 Transformer 43 Transformer drive unit 45 (For transformer drive) Power supply 100 Power supply zero cross detection unit 101, 105 Hold circuit 102, 106 A / D converter 103, 107 Filter circuit 104, 108 Comparator 201, 202 AC power supply

Claims (23)

A power supply unit;
A booster that boosts an output voltage from the power supply;
A commutation section that forms a commutation path that is a current path outside the boosting section;
A smoothing unit that smoothes the output voltage from the boosting unit;
At least one of a control current detection unit that detects a current flowing through the boosting unit and a voltage detection unit that detects a voltage across the smoothing unit;
An abnormality determination current detection unit for detecting a current flowing between the boosting unit and the smoothing unit;
A control unit that controls the boosting unit and the commutation unit based on at least one of the current detected by the control current detection unit and the both-ends voltage;
An abnormality determination processing unit that determines whether or not the commutation unit is abnormal based on the current detected by the abnormality determination current detection unit;
A power conversion device comprising: The boosting unit includes:
Reactor,
A boost switch;
A rectifier,
The power converter according to claim 1, further comprising: The abnormality determination current detection unit is at least one of the boosting switch and the rectifier, the boosting switch and the negative electrode of the smoothing unit, or between the positive electrode of the smoothing unit and the rectifier. The current flowing through
The power conversion device according to claim 2.   The power converter according to claim 2, wherein the abnormality determination current detection unit detects a current at a timing when the boosting switch is turned on.   5. The commutation unit is determined to be abnormal when it is determined that a recovery current is generated based on the current detected by the abnormality determination current detection unit. The power converter described in one. The abnormality determination current detection unit includes:
A hold circuit for holding the current to be measured at a predetermined timing;
An A / D converter for converting a value held by the hold circuit into a digital signal;
The power conversion device according to any one of claims 1 to 5, further comprising:   The power converter according to claim 6, further comprising a noise removal circuit in at least one input stage or output stage of the hold circuit and the A / D converter. The abnormality determination current detection unit includes:
A comparator that binarizes the current to be measured;
With
6. The power conversion device according to claim 1, wherein it is determined whether or not the commutation unit is abnormal based on a signal binarized by the comparator. A noise removal circuit that removes noise from the current to be measured,
With
The power converter according to claim 8, wherein the comparator binarizes a current after noise removal by the noise removal circuit.   The abnormality determination processing unit determines whether or not the current detected by the abnormality determination current detection unit is an abnormal value, and if it is determined to be an abnormal value at a predetermined number of times within a predetermined time Furthermore, it determines with the said commutation part being abnormal, The power converter device as described in any one of Claims 1-9 characterized by the above-mentioned.   The power conversion device according to claim 10, wherein the abnormality determination processing unit determines that the current value detected by the abnormality determination current detection unit is an abnormal value when the current is equal to or greater than a predetermined threshold. The commutation part is
A transformer,
A power supply for driving the transformer;
A commutation switch disposed between the transformer and the power source;
A commutation rectifier connected to the transformer;
The power conversion device according to any one of claims 1 to 11, further comprising: A voltage detector for abnormality determination for detecting a voltage across the switch for commutation,
The power according to claim 12, wherein the abnormality determination processing unit determines whether or not the commutation unit is abnormal based on a both-end voltage detected by the abnormality determination voltage detection unit. Conversion device.   The abnormality determination processing unit determines whether or not the commutation unit is abnormal based on both-end voltages detected by the abnormality determination voltage detection unit in both the ON section and the OFF section of the commutation switch. The power conversion device according to claim 13, wherein the determination is performed.   The abnormality determination processing unit determines whether or not the voltage detected by the abnormality determination voltage detection unit is an abnormal value, and is determined to be an abnormal value at a predetermined number of times within a predetermined time. The power conversion device according to claim 13 or 14, wherein the commutation unit is determined to be abnormal.   The power converter according to claim 15, wherein the abnormality determination processing unit determines that the value is an abnormal value when the voltage detected by the abnormality determination voltage detection unit is equal to or greater than a predetermined threshold.   The power converter according to any one of claims 12 to 16, wherein the commutation rectifier is formed of a wide band gap semiconductor.   The power converter according to claim 17, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.   The abnormality determination processing unit, when determining that the commutation unit is abnormal, controls to stop at least one of a boost operation, a commutation operation, and a power supply. The power converter device as described in any one of 1-18. A power supply unit;
A booster that boosts an output voltage from the power supply;
A commutation section that forms a commutation path that is a current path outside the boosting section;
At least one of a control current detection unit that detects a current flowing through the boosting unit and a voltage detection unit that detects a voltage across the smoothing unit;
An abnormality determination voltage detection unit for detecting a voltage across the commutation switch in the commutation unit;
The control current detection unit is configured to control the boosting unit based on at least one of the detected current and the both-ends voltage;
An abnormality determination processing unit that determines whether or not the commutation unit is abnormal based on the both-end voltage detected by the abnormality determination voltage detection unit;
A power conversion device comprising:   The power converter according to any one of claims 1 to 20, wherein the abnormality determination processing unit is provided in the control unit.   A refrigerating and air-conditioning system comprising the power conversion device according to any one of claims 1 to 21. A power supply unit, a boost unit that boosts the output voltage from the power supply unit, a commutation unit that forms a commutation path that is a current path outside the boost unit, and a smoothing output voltage from the boost unit At least one of a smoothing unit that performs detection, a control current detection unit that detects a current flowing through the boosting unit, and a voltage detection unit that detects a voltage across the smoothing unit, and the control current detection unit includes: A control method in a power converter comprising: a control unit that controls the boosting unit and the commutation unit based on at least one of a detected current and the both-end voltage,
A current detection step of detecting a current flowing between the boosting unit and the smoothing unit;
An abnormality determination processing step for determining whether or not the commutation unit is abnormal based on the current detected in the current detection step;
The control method characterized by including.

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