JP2011139559A - Inverter control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly detect an open phase without misdetection, concerning an inverter control apparatus which drives an AC motor. <P>SOLUTION: The inverter control apparatus has an inverter device, which drives at least one or more AC motors, a means, which gets a current value that flows in the AC motors, a converter which converts the coordinates of the current value flowing into the AC motors, and a generator which generates a voltage command and a frequency command to the inverter device, based on the current value obtained from the converter for coordinate conversion. It detects a frequency component double the frequency command to the inverter device from the current value obtained from the converter for coordinate conversion, and computes a current value to be used for detection of an open phase, and detects the open phase of the inverter device when the value is over the determination value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inverter control device that drives an AC motor.

  In the field of railway vehicles, a system for driving a vehicle with an AC motor connected to an inverter device is widely used. Since AC motors and inverter devices are important devices for driving vehicles, various types of failure detection are implemented in order to protect them from overvoltage and overcurrent.

  One of them is detection of a phase failure caused by disconnection of the wiring between the inverter device and the AC motor. When phase loss occurs, current concentrates on the phase that is not phase-opened, causing burnout of the AC motor and destruction of the inverter device. Further, even if the inverter device is not destroyed, abnormal torque vibration occurs in the AC motor, so that it is essential to quickly detect and stop the inverter device.

  On the other hand, in Patent Document 1, a current flowing into an AC motor is detected, and the detected current value has a shaft in a direction perpendicular to the magnetic flux direction of the AC motor and rotates in synchronization with the magnetic flux inside the AC motor. A method is described in which a phase loss is detected when the rate of change in the current value in the direction of the magnetic flux axis exceeds a determination value after coordinate transformation on the coordinate system.

  By this method, it is possible to quickly detect when an open phase occurs. In addition, a method of detecting a phase failure when a state in which the rate of change of the current value in the direction of the magnetic flux axis exceeds the determination value continues for a predetermined time is also described to prevent erroneous detection.

JP 2003-348898 A

Takayoshi Nakano Vector control of AC motors Nikkan Kogyo Shimbun

  However, in Patent Document 1, the current value in the direction of the magnetic flux axis of the AC motor is monitored, and an open phase is detected when the rate of change becomes equal to or higher than the determination value. However, the rate of change in current becomes equal to or higher than the determination value. When such a vibration occurs, the condition for detecting the phase loss is satisfied. Therefore, for example, a vibration generated due to a control abnormality due to a software defect or the like may be erroneously detected as a phase loss.

  An object of the present invention is to quickly detect an open phase without erroneous detection in an inverter control device that drives an AC motor.

  The inverter control device of the present invention will be described in detail in the embodiment of the present invention. However, when a phase loss occurs, the current value in the magnetic flux direction of the AC motor and the current value in the direction orthogonal thereto are determined by the frequency command for the inverter device. Vibrates at twice the frequency. Therefore, by detecting the phase loss by paying attention to the frequency component, it is possible to perform phase loss detection with fewer false detections in the same detection time as that of the known technology.

  An inverter control device according to the present invention includes an inverter device for driving at least one AC motor, a means for obtaining a current value flowing into the AC motor, a means for coordinate converting the current value flowing into the AC motor, and a coordinate conversion Having a means for generating a voltage command and a frequency command for the inverter device based on the current value obtained from the means for performing a frequency component that is twice the frequency command for the inverter device from the current value obtained from the means for coordinate conversion Is detected and the current value used for the phase loss detection is calculated, and when the value exceeds the determination value, the phase loss of the inverter device is detected.

  According to the present invention, in the inverter control device that drives the AC motor, it is possible to quickly detect the phase loss without erroneous detection.

FIG. 1 is a diagram showing a first embodiment to which the present invention is applied. FIG. 2 is a diagram showing Iu, Iv, and Iw when an open phase occurs. FIG. 3 is a diagram showing Id and Iq when an open phase occurs. FIG. 4 is a diagram showing Ie in the first embodiment. FIG. 5 is a diagram showing a second embodiment to which the present invention is applied. FIG. 6 is a diagram showing a third embodiment to which the present invention is applied. FIG. 7 is a diagram showing Idh and Iqh when an open phase occurs. FIG. 8 is a diagram showing Ie in the third embodiment. FIG. 9 is a diagram showing a fourth embodiment to which the present invention is applied. FIG. 10 is a diagram showing a fifth embodiment to which the present invention is applied. FIG. 11 is an explanatory diagram of the fifth embodiment. FIG. 12 is a diagram showing a sixth embodiment to which the present invention is applied.

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

  A first embodiment of the inverter control apparatus according to the present invention will be described with reference to FIGS. In FIG. 1, an inverter device 1 converts DC power into three-phase AC power and outputs it. The AC motor 2 receives the three-phase AC power output from the inverter device 1 as an input, converts it into shaft torque, and outputs it. In FIG. 1, the AC motor is described as one unit, but a configuration in which a plurality of AC motors are driven by one inverter device may be used.

  The current detection means 3 detects currents Iu, Iv and Iw flowing into the AC motor 2. The coordinate conversion means 4 coordinates Iu, Iv, and Iw into current in the magnetic flux direction of the AC motor 2 (hereinafter referred to as d-axis current) Id and current in a direction orthogonal to the magnetic flux (hereinafter referred to as q-axis current) Iq. Convert.

  The current control means 5 is based on Id and Iq, a command value for Id (not shown here), a command value for Iq, rotational speed information of the AC motor 2, a resistance value and an inductance value of the AC motor 2, A voltage command Vd in the d-axis direction, a voltage command Vq in the q-axis direction, and a frequency command Fi are output to the inverter device 1. The details of the control method of the AC motor are described in Non-Patent Document 1, for example, and are omitted because they are known techniques. The item numbers after the filter 6 will be described later.

  Here, the principle of phase loss detection in the present invention will be described. FIG. 2 illustrates currents Iu, Iv, and Iw flowing into the AC motor 2. The horizontal axis represents time. At time Te, an open phase occurs and Iu is zero.

  The AC motor is structurally Iu + Iv + Iw = 0. At this time, Iu, Iv, and Iw are each a sine wave having a phase difference of 120 degrees, and the frequency is a frequency command Fi for the inverter device. After the phase loss occurs (after time Te), the frequency is the same as before the phase loss occurrence, but Iv and Iw are sine waves having a phase difference of 180 degrees.

  FIG. 3 shows Id and Iq at this time. Before phase loss occurs, both Id and Iq are DC amounts, but after phase loss occurs, both Id and Iq vibrate at twice the frequency of Iu, Iv, and Iw.

  From this, it is possible to detect an open phase by paying attention to an AC component twice the frequency command Fi for the inverter device included in Id and Iq.

  The configuration of the phase loss detection will be described again with reference to FIG. The filter 6 and the filter 7 are high-pass filters or band-pass filters that detect AC components twice as large as Fi included in Id and Iq, respectively.

  As described above, when phase loss occurs, Id and Iq vibrate at a frequency twice that of Fi. For this reason, erroneous detection can be suppressed by detecting the frequency component twice as high as Fi included in Id and Iq by the filters 6 and 7 and detecting phase loss.

Ｉｅを図示すると図４のようになる。欠相発生前のＩｅは０だが、欠相発生後はある大きさの値を示す。本発明のように、｜Ｉｄｈ｜と｜Ｉｑｈ｜を加算して欠相検知に用いる電流値Ｉｅとすることで、Ｉｅはほぼ直流量となるため判定が容易になり、誤検知の可能性を低減できる。 The absolute value calculation means 8 outputs the absolute value | Idh | of the alternating current component Idh of Id that is the output of the filter 6. The absolute value calculation means 9 outputs the absolute value | Iqh | of the alternating current component Iqh of Iq that is the output of the filter 7. The adder 10 adds | Idh | and | Iqh | and outputs a current value Ie used for phase loss detection.

Ie is illustrated in FIG. Ie before the occurrence of phase loss is 0, but shows a certain value after the occurrence of phase loss. As in the present invention, by adding | Idh | and | Iqh | to obtain the current value Ie used for the phase loss detection, Ie is almost a direct current amount, so that the determination becomes easy and the possibility of erroneous detection is increased. Can be reduced.

  The determination value setting unit 11 sets a determination value Ie0 for phase loss detection. The comparator 12 compares Ie and Ie0 and outputs a first open phase detection signal Se1 if Ie is greater than Ie0.

  A second embodiment of the inverter control device of the present invention will be described with reference to FIG. The difference from the first embodiment is that a delay time element 13 is provided at the output stage of the comparator 12.

  The delay time element 13 outputs a second phase loss detection signal Se2 when the first phase loss detection signal Se1 output from the comparator 12 continues for a certain time. As a result, phase failure detection is performed when Ie is greater than Ie0 for a certain period of time, so that erroneous detection due to a change in operation command or current vibration caused by a failure other than phase failure can be avoided. The time until Se2 is output is set to such an extent that no phase loss is erroneously detected.

  For example, in the case of a railway vehicle, the frequency command Fi for the inverter device is about 250 Hz at the maximum. Therefore, when an open phase occurs, vibrations of about 500 Hz at maximum occur in Id and Iq.

  Therefore, it is preferable that the time until Se2 is output be equal to or longer than one period (1/500 = 2 ms) of the maximum vibration frequency generated in Id and Iq when phase loss occurs.

図６において、インバータ装置１は、直流電力を３相交流電力に変換して出力する。交流電動機２は、前記インバータ装置１から出力される前記３相交流電力を入力として、これを軸トルクに変換して出力する。図６では、交流電動機を１台として記載しているが１台のインバータ装置で複数台の交流電動機を駆動する構成でもよい。 A third embodiment of the inverter control device of the present invention will be described with reference to FIGS. The difference from the first embodiment is that, instead of adding | Idh | and | Iqh | to obtain the current value Ie used for phase loss detection, the root mean square value of Idh and Iqh is set to Ie.

In FIG. 6, the inverter device 1 converts DC power into three-phase AC power and outputs it. The AC motor 2 receives the three-phase AC power output from the inverter device 1 as an input, converts it into shaft torque, and outputs it. In FIG. 6, the AC motor is described as one unit, but a configuration in which a plurality of AC motors are driven by one inverter device may be used.

  The current detection means 3 detects currents Iu, Iv and Iw flowing into the AC motor 2. The coordinate conversion means 4 performs coordinate conversion of Iu, Iv, and Iw into a d-axis current Id and a q-axis current Iq.

  The current control means 5 is based on Id and Iq, a command value for Id (not shown here), a command value for Iq, rotational speed information of the AC motor 2, a resistance value and an inductance value of the AC motor 2, A voltage command Vd in the d-axis direction, a voltage command Vq in the q-axis direction, and a frequency command Fi are output to the inverter device 1.

  The filter 6 and the filter 7 are high-pass filters or band-pass filters that detect AC components twice as large as Fi included in Id and Iq, respectively. The root mean square calculating means 14 obtains the root mean square value of the alternating current component Idh of Id that is the output of the filter 6 and the alternating current component Iqh of Iq that is the output of the filter 7 and outputs a current value Ie used for phase loss detection. . FIG. 7 shows Idh as a horizontal axis and Iqh as a vertical axis. When phase loss occurs, Idh and Iqh draw a circle that rotates at a frequency twice that of Fi. Therefore, the root mean square value of Idh and Iqh corresponds to the radius of this circle.

  Ie is illustrated in FIG. Compared with Ie of the first embodiment, the calculation is complicated, but the effect of suppressing the erroneous detection of the missing phase by reducing the pulsation can be expected.

  The determination value setting unit 11 sets a determination value Ie0 for phase loss detection. The comparator 12 compares Ie and Ie0 and outputs a first open phase detection signal Se1 if Ie is greater than Ie0.

  A fourth embodiment of the inverter control apparatus of the present invention will be described with reference to FIG. The difference from the third embodiment is that a delay time element 13 is provided at the output stage of the comparator 12.

  The delay time element 13 outputs a second phase loss detection signal Se2 when the first phase loss detection signal Se1 output from the comparator 12 continues for a certain time. As a result, phase failure detection is performed when Ie is greater than Ie0 for a certain period of time, so that erroneous detection due to a change in operation command or current vibration caused by a failure other than phase failure can be avoided. The time until Se2 is output is set to such an extent that no phase loss is erroneously detected.

  For example, in the case of a railway vehicle, the frequency command Fi for the inverter device is about 250 Hz at the maximum. Therefore, when an open phase occurs, vibrations of about 500 Hz at maximum occur in Id and Iq.

  Therefore, it is preferable that the time until Se2 is output be equal to or longer than one period (1/500 = 2 ms) of the maximum vibration frequency generated in Id and Iq when phase loss occurs.

  A fifth embodiment of the inverter control apparatus of the present invention will be described with reference to FIG. A difference from the first to fourth embodiments is that the absolute value of the alternating current component of the filter output | Idh | + | Iqh | or the root mean square value of Idh and Iqh is not used for the phase loss detection, but the filter output The AC component Idh and the AC component Iqh are directly used for phase loss detection.

  In FIG. 10, the AC component Idh of Id that is the output of the filter 6 is compared with the set value Id0 set by the determination value setting means 15 in the comparator 17, and the comparator 17 determines that the AC component Idh is the set value Id0. If it exceeds, output is performed, and the flip-flop 19 is set to ON. Similarly, the alternating current component Iqh of Iq that is the output of the filter 7 is compared with the set value Iq0 set by the determination value setting means 16 in the comparator 18, and the comparator 18 determines that the alternating current component Iqh is the set value. When it becomes larger than Iq0, an output is made and the flip-flop 20 is set to ON.

  The outputs of the flip-flop 19 and the flip-flop 20 are input to an AND circuit (AND circuit) 21. The AND circuit (AND circuit) 21 outputs an open phase detection signal when the open phase occurs.

  FIG. 11 shows that Id and Iq generated at the occurrence of phase loss are the AC component Idh and AC component Iqh of Id detected by the filter 6 and the filter 7, respectively, and the judgment value setting means 15 and 16 respectively. The relationship between the set values Id0 and Iq0 is shown.

  When the AC components Idh and Iqh are larger than the set values Id0 and Iqo, the comparators 17 and 18 are output. When both of the AC components Idh and Iqh are larger than the set values Id0 and Iqh, a logical product circuit (AND circuit) ) 21 outputs an open phase detection signal. By using the AND circuit (AND circuit) 21, the phase loss detection can be performed more reliably.

  A sixth embodiment of the inverter control apparatus of the present invention will be described with reference to FIG. The difference from the first to fifth embodiments is that the absolute value of the alternating current component of the filter output | Idh | + | Iqh | or the root mean square value of Idh and Iqh is not used for phase loss detection, but the filter output Are different from the fifth embodiment in that an OR circuit (OR circuit) 22 is used in place of the AND circuit (AND circuit) 21. This is the point used.

  In FIG. 12, the AC component Idh of Id that is the output of the filter 6 is compared with the set value Id0 set by the determination value setting means 15 in the comparator 17, and the comparator 17 determines that the AC component Idh is the set value Id0. If it exceeds, output is performed, and the flip-flop 19 is set to ON. Similarly, the alternating current component Iqh of Iq that is the output of the filter 7 is compared with the set value Iq0 set by the determination value setting means 16 in the comparator 18, and the comparator 18 determines that the alternating current component Iqh is the set value. When it becomes larger than Iq0, an output is made and the flip-flop 20 is set to ON.

  The outputs of the flip-flop 19 and the flip-flop 20 are input to an OR circuit (OR circuit) 22, and the OR circuit (OR circuit) 22 outputs a phase loss detection signal when phase loss occurs.

  When the AC components Idh and Iqh are larger than the set values Id0 and Iqo, the comparators 17 and 18 are output. When one of the AC components Idh and Iqh is larger than the set values Id0 and Iqh, an OR circuit (OR circuit) ) 22 outputs an open phase detection signal. By using the logical sum (OR circuit) 22, the phase loss detection can be performed more quickly.

  The present invention is not limited to the field of railway vehicles, and failure detection that protects AC motors and inverter devices from overvoltage and overcurrent is an important function. By using the phase loss detection method of the present invention, rapid detection is possible without erroneous detection of phase loss, and therefore, development in various fields can be expected.

DESCRIPTION OF SYMBOLS 1 Inverter apparatus 2 AC motor 3 Current detection means 4 Coordinate conversion means 5 Current control means 6 High pass filter or band pass filter 7 High pass filter or band pass filter 8 Absolute value calculation means 9 Absolute value calculation means 10 Adder 11 Determination value setting means DESCRIPTION OF SYMBOLS 12 Comparator 13 Delay time element 14 Mean square calculating means 15 Judgment value setting means 16 Judgment value setting means 17 Comparator 18 Comparator 19 Flip-flop 20 Flip-flop 21 AND circuit (AND circuit)
22 OR circuit (OR circuit)
Fi Frequency command Vd Voltage command in the d-axis direction Vq Voltage command in the q-axis direction Iu, Iv, Iw AC current flowing into the AC motor Id Current value in the d-axis direction Iq Current value in the q-axis direction Idh Id Alternating current component included in Iqh Iq Determination value for phase loss detection Ie Current value used for phase loss detection Se1 First phase loss detection signal Se2 Second phase loss detection signal Te Time when phase loss occurred

Claims (8)

It is obtained from an inverter device for driving at least one AC motor, means for obtaining a current value flowing into the AC motor, means for converting the current value flowing into the AC motor, and means for converting the coordinate. In the inverter control device having means for generating a voltage command and a frequency command for the inverter device based on the current value,
Means for obtaining an AC component included in the current value obtained from the means for coordinate conversion, means for obtaining a current value used for phase loss detection of the inverter device based on the AC component, and determination value for phase loss detection And means for obtaining
An inverter control device that detects a phase failure of the inverter device when a current value used for the phase loss detection becomes equal to or greater than the determination value. It is obtained from an inverter device for driving at least one AC motor, means for obtaining a current value flowing into the AC motor, means for converting the current value flowing into the AC motor, and means for converting the coordinate. In the inverter control device having means for generating a voltage command and a frequency command for the inverter device based on the current value,
Means for obtaining an AC component included in the current value obtained from the means for coordinate conversion, means for obtaining a current value used for phase loss detection of the inverter device based on the AC component, and determination value for phase loss detection And means for obtaining
An inverter control device that detects a phase failure of the inverter device when a state in which a current value used for the phase loss detection is equal to or greater than the determination value continues for a predetermined time.   3. The inverter control device according to claim 1, wherein the coordinate converting means converts the current value flowing into the AC motor into a direction perpendicular to the magnetic flux direction inside the AC motor and the AC current. An inverter control device that converts into a coordinate system that rotates in synchronization with a magnetic flux inside an electric motor. 4. The inverter control device according to claim 3, wherein the means for obtaining the alternating current component is orthogonal to the first alternating current component and the magnetic flux included in the current value in the magnetic flux direction inside the alternating current motor obtained from the coordinate converting means. Obtaining a second AC component included in the current value in the direction of
The means for obtaining a current value used for phase loss detection of the inverter device is used for phase loss detection by adding the absolute value of the first AC component and the absolute value of the second AC component. . 4. The inverter control apparatus according to claim 3, wherein the means for obtaining the alternating current component is orthogonal to the first alternating current component and the magnetic flux included in the current value in the magnetic flux direction of the alternating current motor obtained from the coordinate converting means. Obtaining a second AC component included in the current value of the direction,
The means for obtaining a current value used for phase loss detection of the inverter device uses an absolute value of the first AC component and a root mean square value of the second AC component for phase loss detection.   6. The inverter control device according to claim 1, wherein the means for obtaining the AC component is a high-pass filter or a band capable of obtaining a frequency component twice a frequency command for the inverter device. An inverter control device characterized by being a pass filter. 4. The inverter control device according to claim 3, wherein the means for obtaining the alternating current component is orthogonal to the first alternating current component and the magnetic flux included in the current value in the magnetic flux direction inside the alternating current motor obtained from the coordinate converting means. Obtaining a second AC component included in the current value in the direction of
The means used for phase loss detection of the inverter device compares a first alternating current component with a first predetermined value, compares a second alternating current component with a second predetermined value, and the first alternating current component is An inverter control device that outputs an open phase detection signal when the second predetermined AC value is greater than the first predetermined value and the second AC component is greater than the second predetermined value. 4. The inverter control device according to claim 3, wherein the means for obtaining the alternating current component is orthogonal to the first alternating current component and the magnetic flux included in the current value in the magnetic flux direction inside the alternating current motor obtained from the coordinate converting means. Obtaining a second AC component included in the current value in the direction of
The means used for phase loss detection of the inverter device compares a first alternating current component with a first predetermined value, compares a second alternating current component with a second predetermined value, and the first alternating current component is An inverter control device that outputs an open phase detection signal when the first predetermined value is exceeded or the second alternating current component is larger than the second predetermined value.

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