JP6169474B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device equipped with an output side phase loss detection function.

  As a background art in this technical field, there is JP 2012-5257 A (Patent Document 1). In this publication, “the output current of a power converter (inverter) is detected by a detector and its polarity is determined by a determiner, and the output current is divided into six regions divided by its zero cross point and polarity. It is determined by a determiner, and it is determined by a circuit whether or not each region transitions in a certain order, and if it does not transition in a certain order, it is determined that at least one phase is missing. (See summary).

JP 2012-5257 A

  However, according to the invention disclosed in Patent Document 1, it is necessary to always monitor the transition state of the output current region and determine the open phase state. Further, it is not described that which phase is missing. Furthermore, according to the invention disclosed in Patent Document 1, a current detector for three phases is required, and there is a disadvantage that the size of the power conversion device is increased.

  The present invention is an inexpensive and small-sized power conversion that can more easily determine the phase failure state and determine which phase is lost compared to the prior art including the invention disclosed in Patent Document 1. An object is to provide an apparatus.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

  The present application includes a plurality of means for solving the above-described problems. To give an example, a power converter that outputs three-phase AC power to drive an AC motor, and a three-phase output of the power converter. A current detection unit that detects at least two phases of the current; an edge conversion unit that converts the current detected by the current detection unit into an edge; and an edge determination that determines an open phase from the edge converted by the edge conversion unit And the edge discriminating unit compares each of the converted edges and detects at least one missing phase.

  According to the present invention, it is possible to more easily determine the phase loss state by simply detecting the current of the two output phases of the power converter, and to determine which phase is missing. Further, according to the present invention, it is possible to configure a power converter equipped with an output side phase loss detection function at a low cost and in a small size.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is an example of a block diagram of the power converter device which performs an output phase loss detection using at least two current detectors. It is an example of the related figure of a current waveform and an edge. It is an example of the flowchart explaining the process of an edge discrimination | determination part. It is an example of the relationship diagram of an electric current waveform and edge when a v phase is open phase. It is an example of the detailed figure which showed the power converter concretely. FIG. 5 is an example of a relationship diagram between a current waveform and an edge when a u-phase lower arm is in phase loss. FIG. 10 is an example of a relationship diagram between a current waveform and an edge when the lower arm of the v phase is lost. It is an example of a relationship diagram of a rising edge threshold 203, a falling edge threshold 204, a rising edge auxiliary threshold 205, a falling edge auxiliary threshold 206, and a u-phase current 801. It is an example of a relationship diagram of a rising edge threshold value 203, a falling edge threshold value 204, a rising edge auxiliary threshold value 205, a falling edge auxiliary threshold value 206, and three-phase currents 901 to 903.

Hereinafter, examples will be described with reference to the drawings.

  In the present embodiment, an example of the configuration of a power conversion device that performs output phase loss detection using at least two current detectors will be described.

  FIG. 1 is an example of a configuration diagram of a power conversion device that performs output phase loss detection using at least two current detectors of the present embodiment.

  The power converter 101 includes a smoothing capacitor 102, a power converter 103, a current detector 104, an AC motor 105, an open phase detection module 106, a current acquisition unit 107, an edge conversion unit 108, an edge determination unit 109, and an open phase detection unit 110. Have

  The smoothing capacitor 102 is a smoothing capacitor for smoothing a DC voltage. The power converter 103 converts the smoothed direct current into alternating current. The current detector 104 detects, for example, a u-phase / w-phase two-phase current among the three-phase output currents of the power converter 103. The AC motor 105 is driven by obtaining an output from the power converter 103. The phase loss detection module 106 acquires the output current feedback signal of the current detector 104.

  Hereinafter, the internal configuration of the phase loss detection module 106 will be described.

  The current acquisition unit 107 acquires the output current feedback signal of the current detector 104. Further, the edge conversion unit 108 converts the output current feedback signal given by the current acquisition unit 107 into an edge. The edge discriminating unit 109 discriminates the presence / absence of the edge and the edge pattern converted by the edge converter 108. When the edge discriminator 109 determines that the phase loss is detected, the phase loss detection unit 110 determines that the phase loss is detected. The display unit 111 displays the state of the phase loss detection unit 110. The phase loss state signal output unit 112 outputs the state of the phase loss detection unit 110.

  FIG. 2 is an example of a relationship diagram between current waveforms and edges.

  The current 201 is, for example, a current acquired from the detector 104 attached to the u phase. The rising edge threshold 203 is set to a value of + 5% such as the rated current or no-load current of the AC motor to be driven, for example. The falling edge threshold value 204 is set to a value of −5% such as the rated current or no-load current of the AC motor to be driven, for example. The rising edge auxiliary threshold value 205 is set to, for example, a value of + 3% of the rated current or no-load current of the driving AC motor. The falling edge auxiliary threshold 206 is set to a value of −3% such as the rated current or no-load current of the AC motor to be driven. The reason for setting these is that when the current 201 passes near the zero point, the current value at the normal time and the current value at the open phase cannot be distinguished. Also, the rising edge threshold value 203 and the rising edge auxiliary threshold value 205, and the falling edge threshold value 204 and the falling edge auxiliary threshold value 206 may be the same value or different values. The edge 202 becomes +1 at the moment when the value of the current 201 exceeds the rising edge auxiliary threshold value 205 or the rising edge threshold value 203, and becomes -1 at the moment when the current edge value exceeds the falling edge auxiliary threshold value 206 or the falling edge threshold value 204. 0.

  FIG. 3 is an example of a flowchart for explaining the processing of the edge determination unit 109.

  The edge determination unit 109 performs edge acquisition processing S301, for example, u-phase rising edge / falling edge detection processing S302, rising edge detection determination processing S303, u-phase lower arm phase loss processing S304, falling edge detection determination processing S305, The u-phase upper arm phase loss process S306, the phase loss detection process S307, the auxiliary phase loss detection process S308, and the non-phase loss process S309 are included. Further, the edge determination unit 109 can perform three-phase phase loss determination. The first is the phase loss determination of the upper arm, the second is the phase loss determination of the lower arm, and the third is the phase loss of the upper and lower arms.

  The edge acquisition process S301 acquires a rising edge if the edge value converted by the edge converter 108 is +1, a falling edge if it is -1, and no edge if it is 0. The rising edge / falling edge detection determination process S302 is a determination process for determining whether the edge acquired from the edge acquisition process S301 is detected once for the rising edge and once for the falling edge during one cycle of the output voltage or the acquisition current. . If the determination result of the rising edge / falling edge detection process S302 is Yes, it is determined that the phase is not lost. If the determination result is No, the process proceeds to the next rising edge detection determination process S303. The rising edge detection determination process S303 is a determination process as to whether or not a rising edge is detected once during one cycle of the output voltage and the acquired current. If the determination result of the rising edge detection determination process S303 is Yes, the lower arm phase loss process S304 outputs a lower arm phase loss state. If the determination result is No, the process proceeds to the next falling edge detection determination process S305. The falling edge detection determination process S305 is a determination process of whether or not the falling edge is detected once during one cycle of the output voltage or the acquisition current. When the determination result of the falling edge detection determination process S305 is Yes, the upper arm phase loss process S306 outputs the upper arm phase loss state. When the determination result is No, the process proceeds to the next auxiliary phase loss detection determination process S308. The auxiliary phase loss detection determination process S308 is a determination process for determining whether the output voltage or acquired current of any other or other phase has exceeded the rising edge auxiliary threshold value 205 or the falling auxiliary threshold value 206 during one cycle. When the determination result of the auxiliary phase loss detection determination processing S308 is YES, the phase loss detection processing S307 outputs the phase failure state of the u phase. When the determination result is NO, the phase loss detection processing S309 indicates that the phase loss of the u phase is not performed. Output the status.

  In the embodiment, the determination method in one cycle of the output voltage and the acquisition current is described, but it is also possible to make the determination over several cycles.

  FIG. 4 is an example of the relationship between the current waveform and the edge when the v phase is lost.

  The u-phase current 401 and the w-phase current 402 are currents when the v-phase is lost. The u-phase edge 403 is +1 when the u-phase current 401 is the value of the rising edge auxiliary threshold 205 or the rising edge threshold 203, and is -1 when the falling edge auxiliary threshold 206 or the falling edge threshold 204 is set, and 0 otherwise. Become. The w-phase edge 404 is +1 when the w-phase current 402 is the value of the rising edge assist threshold 205 or the rising edge threshold 203, and is -1 when the falling edge assist threshold 206 or the falling edge threshold 204 is set, and 0 otherwise. Become. The edge discriminating unit can detect that the u-phase edge 403 and the w-phase edge 404 are simultaneously generated, and discriminate the v-phase missing phase in which no current is detected.

  The phase loss detection unit 110 notifies the external phase of the phase loss detection module 106 of the phase loss state. For example, when the phase loss detection unit 110 detects the phase loss, the phase loss state is displayed by notifying the display unit 111 of FIG. 1 using communication or the like. In addition, the phase loss detection unit 110 notifies the phase loss state output unit 112 of the phase loss state, and the phase loss state output unit 112 outputs a phase loss detection signal to notify that there is a phase loss state, a terminal, etc. Report to the outside via.

  In the present embodiment, an example of the configuration of arm phase loss detection in the power converter 103 illustrated in FIG. 1 will be described.

  FIG. 5 is an example of a detailed diagram specifically showing the power converter. The power converter 103 includes six arms, an upper arm group 501 and a lower arm group 502. Further, the power converter 103 is composed of a u-phase upper and lower arm, a w-phase upper and lower arm, and a v-phase upper and lower arm from the current detector 104.

  FIG. 6 is an example of a relationship diagram between the current waveform and the edge when the u-phase lower arm is open.

  The lower arm phase loss current 601 is, for example, a current acquired from the current detector 104 attached to the u phase. The edge 602 becomes +1 at the moment when the value of the lower arm phase loss current 601 exceeds the rising edge assist threshold value 205 or the rising edge threshold value 203, but there is a moment when the value exceeds the falling edge assist threshold value 206 or the falling edge threshold value 204. It remains 0 because it does not. When the falling edge cannot be detected, it can be determined that the lower arm of the phase in which the current is detected is missing.

  FIG. 7 is an example of an edge determination unit when the lower arm of the v-phase is lost.

  The u-phase current 701 and the w-phase current 702 are currents when the lower arm of the v-phase is lost. The u-phase edge 703 is +1 when the u-phase current 701 is the value of the rising edge assist threshold 205 or the rising edge threshold 203, and is -1 when the falling edge assist threshold 206 or the falling edge threshold 204 is set, and 0 otherwise. Become. The w-phase edge 704 is +1 when the w-phase current 702 is the value of the rising edge assist threshold 205 or the rising edge threshold 203, and is -1 when the falling edge assist threshold 206 or the falling edge threshold 204 is 0, and 0 otherwise. Become. The u-phase edge 703 and the w-phase edge 704 are generated in the order of the w-phase edge 704, the u-phase edge 703, the u-phase edge 703, and the w-phase edge 704. When there is no phase loss, the u-phase edge 703 and the w-phase edge 704 are alternately generated with the u-phase edge 703 and the w-phase edge 704. It is possible to determine the phase loss. Similarly, when the rotation direction of the AC motor 105 is reversed, when the lower arm of the v-phase is lost, each edge generation pattern includes the u-phase edge 703, the w-phase edge 704, the u-phase edge 703, and the w-phase. Since the order is the edge 704, it is possible to detect an open phase.

  The phase loss detection unit 110 notifies the external phase of the phase loss detection module 106 of the phase loss state. For example, when the phase loss detection unit 110 detects the phase loss, the phase loss state is displayed by notifying the display unit 111 of FIG. 1 using communication or the like. In addition, the phase loss detection unit 110 notifies the phase loss state output unit 112 of the phase loss state, and the phase loss state output unit 112 outputs a phase loss detection signal to notify that there is a phase loss state, a terminal, etc. Report to the outside via.

  In the present embodiment, an example of the configuration of a power conversion device that performs output phase loss detection using at least two current detectors will be described. Since the configuration has the same function as the configuration with the same reference numerals shown in FIG. 1 already described, description thereof will be omitted. Among these, a detailed example in the auxiliary phase loss determination processing S308 shown in FIG. 3 will be described.

  FIG. 8 is an example of a relationship diagram of the rising edge threshold 203, the falling edge threshold 204, the rising edge auxiliary threshold 205, the falling edge auxiliary threshold 206, and the u-phase current 801.

  The u-phase current 801 is a current when the rising edge auxiliary threshold 205 or the falling edge auxiliary threshold 206 is not exceeded. At this time, in the edge converter 108, the u-phase current is not converted into an edge because it does not exceed the rising edge threshold 203, the falling edge threshold 204, the rising edge auxiliary threshold 205, and the falling edge auxiliary threshold 206. Therefore, no edge is acquired even in the edge acquisition S301 of FIG. 3, and NO is determined in the rising edge / falling edge detection determination processing S302. NO is also determined in the next rising edge detection determination process S303, and NO is also determined in the next falling edge detection determination process S305. If the w-phase current other than the u-phase current exceeds the rising edge threshold value 203 or the rising edge auxiliary threshold value 205 or the falling edge threshold value 204 or the falling edge auxiliary threshold value 206 in the last auxiliary phase loss determination process S308, YES Is determined, the u phase is determined to be an open phase, and the w phase current other than the u phase current does not exceed the rising edge threshold 203 or the rising edge auxiliary threshold 205 or the falling edge threshold 204 or the falling edge auxiliary threshold 206, It is determined as NO, and the u phase is determined as an unmissed phase. As an example of the case where the current as shown in FIG. 8 can be obtained, there are some examples, such as when an AC motor less than the rated output of the power converter is driven, or when the load on the permanent magnet synchronous motor is small. is there.

  FIG. 9 shows an example of a relationship diagram of the rising edge threshold 203, the falling edge threshold 204, the rising edge auxiliary threshold 205, the falling edge auxiliary threshold 206, and the three-phase currents 901 to 903.

  The three-phase currents 901 to 903 are currents when the rising edge auxiliary threshold 205 or the falling edge auxiliary threshold 206 is not exceeded, for example, when the v-phase current 901 is missing. At this time, in the edge conversion unit 108, the v-phase current 901 is not converted into an edge because it does not exceed the rising edge threshold 203, the falling edge threshold 204, the rising edge auxiliary threshold 205, and the falling edge auxiliary threshold 206. Therefore, no edge is acquired even in the edge acquisition S301 of FIG. 3, and NO is determined in the rising edge / falling edge detection determination processing S302. NO is also determined in the next rising edge detection determination process S303, and NO is also determined in the next falling edge detection determination process S305. In the final auxiliary phase loss determination process S308, the u-phase current 902 and the w-phase current 903 other than the v-phase current 901 are set to the rising edge threshold 203, the rising edge auxiliary threshold 205, the falling edge threshold 204, or the falling edge auxiliary threshold 206. If it exceeds, it is determined as YES, so that the v phase is determined to be an open phase.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines are those that are considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

DESCRIPTION OF SYMBOLS 101 ... Power converter 102 ... Smoothing capacitor 103 ... Power converter 104 ... Current detector 105 ... AC motor 106 ... Phase loss detection module 107 ... Current acquisition part 108 ... Edge conversion part 109 ... Edge discrimination | determination part 110 ... Phase loss detection part 111 ... Display unit 112 ... Phase loss state signal output unit 201 ... Current 202 ... Edge 203 ... Rising edge threshold value 204 ... Falling edge threshold value 205 ... Rising edge auxiliary threshold value 206 ... Falling edge auxiliary threshold value S301 ... Edge acquisition process S302 ... Rising edge Edge / falling edge detection determination processing S303 ... Rising edge detection determination processing S304 ... Lower arm phase loss processing S305 ... Falling edge detection determination processing S306 ... Upper arm phase loss processing S307 ... Phase loss detection processing S308 ... Auxiliary phase loss detection determination Process S309 ... Unmissed phase detection process 401 ... u-phase current 402 ... w-phase electricity 403 ... u phase edge 404 ... w phase edge 501 ... upper arm group 502 ... lower arm group 601 ... lower arm phase loss current 602 ... edge 701 ... u phase current 702 ... w phase current 703 ... u phase edge 704 ... w phase Edge 801 ... u-phase current 901 ... v-phase current 902 ... u-phase current 903 ... w-phase current

Claims (5)

A power converter that outputs three-phase AC power to drive the AC motor;
A current detector that detects at least two phases of the three-phase output current of the power converter;
An edge converter that converts the current detected by the current detector into an edge;
An edge discriminating unit for determining a phase failure from the edge converted by the edge converting unit;
With
The edge converter compares the current detected by the current detector with one or more thresholds;
If it is greater than or equal to the threshold value, generate an edge to be a rising edge,
If it is less than or equal to the threshold, an edge is generated to be a falling edge,
The power determination apparatus according to claim 1, wherein the edge determination unit does not determine that there is no phase when it is determined that there is no edge for at least two phases converted by the edge conversion unit. A display unit for displaying information of the power conversion device;
With
2. The power conversion device according to claim 1, wherein, as a result of the determination by the edge determination unit, when it is determined that a phase loss has occurred, the phase loss state is displayed on the display unit or notified to the outside. When an undetected phase is missing in the current detection unit,
The edge converter converts the phase in which the output current is detected into an edge,
At the time of generating each section related to an output voltage with each edge in the edge determination unit,
Power converter according to claim 1 or 2, characterized in that to determine the phase loss. The power converter is composed of six arms,
If the upper or lower arm of the phase is open,
Converts the current detected by said current detecting section to the edge at the edge conversion unit,
When it is determined that the section edge related to a certain output voltage is not generated in the edge determination unit,
Power converter according to claim 1 or 2, characterized by detecting a phase loss. The power converter is composed of six arms,
If the upper or lower arm of the undetected phase is missing,
The edge converter converts the phase in which the output current is detected into an edge,
3. The power conversion device according to claim 1, wherein the edge determination unit detects an open phase from an edge pattern different from that in a normal state.

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