JP2001292580A - Method and apparatus for detecting missing phase of output and inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect a missing phase in the output, even when the amplitude level of three-phase AC current outputted from an inverter is small. SOLUTION: A high-pass filter circuit 7a outputs current values I1U, I1V, I1W obtained by removing offset elements from the current values IU, IV, IW for each phase of the three-phase AC current outputted from the inverter. An absolute value detecting circuit 7b outputs absolute values I2U, I2V, I2W of the current values I1U, I1Vm I1W. A low-pass filter circuit 7c outputs absolute values I3U, I3V, I3W obtained by smoothing the absolute values I2U, I2V, I2W. An apparatus 7 for detecting the missing phase of output detects the missing phase of output, based on the absolute values I3U, I3V, I3W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output phase loss detection and apparatus for detecting an output phase loss of each phase output from an inverter apparatus, and an inverter apparatus using the output phase detection method and apparatus.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of an inverter device for controlling the driving of an AC motor 6. This inverter device comprises a current control circuit 1, a coordinate converter 2,
A WM generation circuit 3, a power converter 4, a current detector 5,
An output phase loss detection device 17 and an inverter protection circuit 8 are provided.

The current control circuit 1 includes a current command value _Iref from a higher-level device (not shown) and a current value of each phase output from the power converter 4 to the AC motor 6 detected by the current detector 5. I _U , I _V , and I _W are input, and the voltage command value V _ref and the phase are obtained from the deviation between the current command value I _ref and the current vector composed of the current values I _U , I _V , and I _{W of} each phase. Angle θ _{r ef}
Is calculated and output.

The coordinate converter 2 has a voltage command value V_refand
Phase angle θ_refAnd the voltage command value V _refAnd the phase angle θ
_refCalculates and outputs the voltage command value of each phase of AC motor 6 from
I do. The pulse width modulation (hereinafter PWM) generating circuit 3
Voltage of each phase of AC motor 6 output from target converter 2
Input a command value and receive a PWM pulse signal by the PWM control method.
Generate a number.

[0005] In the power converter 4, a switching circuit composed of power elements such as transistors and diodes is connected to each phase of the AC motor 6. A DC voltage is applied to the switching circuits, and the power converter 4 receives the PWM pulse signal output from the PWM generation circuit 3 and switches the switching circuits according to the PWM pulse signal. Is converted into a three-phase AC voltage of an arbitrary frequency to drive the AC motor 6.

If such an inverter device cannot supply any one of three-phase currents output to the AC motor 6, it is difficult to drive the AC motor 6 normally. Becomes This phenomenon is called output phase loss. One of the important issues in the inverter device is to detect the output open phase.

Therefore, in the inverter device shown in FIG.
An output phase loss detection device 17 and an inverter protection circuit 8 are provided. The output phase loss detection device 17 performs output phase loss detection based on the three-phase current values I _U , I _V , I _W detected by the current detector 5 and the current command value I _ref, and When a phase is detected, an open phase detection signal is output to the inverter protection circuit 8. The inverter protection circuit 8 performs a protection operation such as stopping the inverter device when the phase loss detection signal is input from the output phase loss detection device 17.

FIG. 5 is a block diagram showing a configuration of a conventional output phase loss detecting device 17. Conventional output open phase detection device 1
7 is an absolute value detection circuit 7b and an operation state comparison circuit 7d
, Open-phase state detection circuit 7e, and duration comparison circuit 7f
And an AND circuit group 7k. The AND circuit group 7k includes AND circuits 7u, 7v, and 7w.

The absolute value detection circuit 7b receives the three-phase current values I _U , I _V and I _W detected by the current detector 5, and
Absolute values I _3U , I _4V , I _{4W of} three-phase current values I _U , I _V , I _W
Is output. The open-phase state detection circuit 7e outputs the absolute values I _4U , I _4V , and I ₄ of the current of each phase output from the absolute value detection circuit 7b.
By comparing the reference value C ₂ is _4W and a second predetermined value, among the signals _{a 2U, a 2V, a 2W} is the second signal, the absolute value I
A signal having a phase in which _4U , I _4V and I _4W are smaller than the reference value C ₂ is output.

On the other hand, the operating state comparator circuit 7d receives the current command value I _ref, is compared with the reference value C ₁ is a first predetermined value and the current command value I _ref. Operation state comparison circuit 7d
Is a reference value C ₁ where the current command value I _ref is a first predetermined value.
And if, and outputs the signal a ₁ is greater than. When the current command value _Iref is small, the amplitude level of the current of each phase output from the inverter device is also small, so that it is not possible to detect the output open phase. That signal a ₁ is output, which means that the amplitude level of each phase of the current output from the inverter device is a level that can detect the output phase.

When both the signal a ₁ and the signal a _2U are input, the AND circuit 7u outputs a signal a _3U which is a third signal. Similarly, the AND circuit 7v, also 7w Similarly, when the signal a ₁ and signal a _2V, and the a _2W are both input, signal a _3V which is the third signal, and outputs the a _3W. Duration comparing circuit 7f, the signal a _3U, a _3V, type the a _3W, the signal a _3U, a _3V, counts the time that a _3W is output, the signals _{a 3U, a 3V, a} of _3W output, when the output of one of the signals is a predetermined time C ₃ continues, it is determined that detects a phase loss for outputting a phase loss detection signal.

On the other hand, when the AC motor 6 shown in FIG. 4 is an induction motor, the amplitude level of the three-phase current output from the inverter device is larger than when the AC motor 6 is a synchronous motor, and The phase loss detecting device 17 can normally detect the output phase loss with the capacity of an arbitrary inverter device. However, when AC motor 6 is a synchronous motor, the amplitude level of the three-phase current output from the inverter device is much smaller than when AC motor 6 is an induction motor. When the AC motor 6 is a synchronous motor and the capacity of the inverter device is small or the load connected to the synchronous motor is small, the amplitude level of each phase current output from the inverter device is further reduced. . When the amplitude level of the current of each phase output from the inverter device is small, the ratio of the ripple component or the offset component included in the current to the amplitude level of the current of each phase output from the inverter device increases. Therefore, when the amplitude level of the current of each phase output from the inverter device is small, the output open phase detection device 17 has a problem that erroneous detection or undetection due to the ripple component and the offset component may occur. .

FIG. 6 is a graph showing a waveform of the absolute value I _4U of the current value I _U output from the absolute value detection circuit 7b.
As shown in FIG. 6, the absolute value I _4U output from the absolute value detection circuit 7b is 0 (A) and the amplitude value of the current value I _U is I
(A) periodically fluctuates. Here, the output open phase detecting device 17 determines the constant value based on the current values I _U , I _V , I _W of each phase of the three-phase AC current discretized at the constant sampling period ΔT and the current command I _ref. It is assumed that the digital processing operates at the sampling period ΔT. Assuming that the sampling period ΔT is substantially the same as the period of the fluctuation of the absolute value I _4U of the current I _U , the output open-phase detecting device 17 determines that the absolute value I _4U of the current value I _U is, as shown in FIG. sometimes Mau have been sampled at a lower timing than the reference value C _2. When the time to continue this state reaches the predetermined time C _3, output phase detector 17, U
It is determined that the phase has been lost, and an output missing phase detection signal is output.

[0014]

As described above, the conventional output phase detection method and apparatus have the following two problems. (1) When the amplitude level of each phase current output from the inverter device is small, the ratio of the ripple component and the offset component included in the current to the current amplitude level increases. For this reason, in the conventional output phase loss detection device, erroneous detection or undetection due to the ripple component and the offset component occurs. (2) When the output phase loss detection device performs the output phase loss based on the current value of each phase discretized at a constant sampling cycle, the output phase loss detection device sets the current value of each phase lower than the reference value. In some cases, a state where sampling is performed at the timing of occurrence may occur. If this state is continued for a predetermined period of time, the output phase loss detecting device determines that the phase has been lost and performs erroneous detection.

An object of the present invention is to provide an output phase loss detection method and apparatus which can reliably detect an output phase loss even when the amplitude level of each phase current output from the inverter device is low. I do.

Further, according to the present invention, even when the output phase loss is detected based on the current value of each phase output from the inverter device, which is discretized at a constant sampling cycle, the output phase loss is reliably detected. It is an object of the present invention to provide a method and an apparatus for detecting an output open phase that can perform the same.

[0017]

In order to solve the above-mentioned problems, according to the method and the apparatus for detecting output phase loss of the present invention, the three-phase alternating current output from the inverter is included in the current value of each phase. The offset component is removed by high-pass filter means, the absolute value of the current value of each phase from which the offset component has been removed by the high-pass filter means, the absolute value of the current value of each phase is smoothed by low-pass filter means, In a state where the current command value output from the host device is larger than the first predetermined value, the absolute value of any one of the absolute values of the current values of the respective phases smoothed by the low-pass filter means If the state smaller than the second predetermined value is continued for a predetermined time, it is determined that an open phase has been detected.

In the method and the apparatus for detecting output phase loss according to the present invention, the offset component, the ripple component and the noise component contained in the current value of each phase can be removed by using the high-pass filter means and the low-pass filter means. Therefore, even when the amplitude level of the current of each phase output from the inverter device is small, it is possible to reliably detect the output missing phase.

Further, in the method and the apparatus for detecting an open phase of the present invention, the absolute value of the current value of each phase is smoothed by using the low-pass filter means. The absolute value of the current value is always equal to or higher than a certain level. Therefore, in the output phase loss detection method of the present invention, even when the output phase loss detection is performed based on the current value of each phase output from the inverter device, which is discretized at a fixed sampling period, the output phase loss detection is reliably performed. Can be detected.

[0020]

Next, a method and an apparatus for detecting an open phase according to an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings, the components denoted by the same reference numerals all indicate the same components. FIG. 1 is a block diagram showing a configuration of an inverter device using the phase loss detection method of the present embodiment. The inverter device of FIG. 1 includes an output open-phase detecting device 7 instead of the output open-phase detecting device 17 provided in the inverter device of FIG. The output phase loss detection device 7 receives the three-phase current values I _u , I _v , I _w detected by the current detector 5 and the current command value I _ref , similarly to the output phase loss detection device 17. , Outputs an open phase detection signal to the inverter protection circuit 8 when the output open phase is detected.

FIG. 2 shows an output phase loss detecting device 7 according to this embodiment.
FIG. 3 is a block diagram showing the configuration of FIG. As shown in FIG. 2, the output phase loss detection device 7 of the present embodiment includes a high-pass filter circuit 7a, an absolute value calculation circuit 7b, a low-pass filter circuit 7c, an operation state comparison circuit 7d, and an open phase state detection circuit. 7e, a duration comparison circuit 7f, and an AND circuit group 7k. The AND circuit group 7k includes AND circuits 7u, 7v, and 7w.

FIG. 3 shows an output phase loss detecting device 7 according to this embodiment.
6 is a graph showing the operation of the above. In FIG. 3, each block 7h
7 to 7j respectively show graphs of waveforms of current values output from the high-pass filter circuit 7a, the absolute value calculation circuit 7b, and the low-pass filter circuit 7c. FIG.
Is a U-phase current value _Iu output from the inverter device. This current value I _u is obtained by adding an offset component ΔI to a sine wave having an angular frequency ω.

The high-pass filter circuit 7a receives the U-phase current value I _U and outputs a current value I _1U obtained by removing the current offset component ΔI from the current value I _U. Its current value I _1U
Is shown in block 7h. Absolute value detection circuit 7b
Inputs the current value I _1U and _calculates the absolute value I _{2U of the} current value I _1U.
Is output. The absolute value I _2U is shown in block 7i of FIG. The low-pass filter circuit 7c receives the absolute value I _2U , smoothes the absolute value I _2U , and outputs the absolute value I _3U shown in the block 7j of FIG. Open-phase state detection circuit 7e
Is the absolute value I output from the low-pass filter circuit 7c.
_3U cases the reference value C ₂ is smaller than outputs a signal a _2U.

On the other hand, the operating state comparator circuit 7d receives the current command value I _ref, is compared with the current command value I _ref and the reference value C _1. If the current command value I _ref is larger than the reference value C _1, the operating state comparator circuit 7d, when the amplitude level of the current being output from the inverter device has reached to a predetermined level appropriate to initiate a phase loss detection it is determined, to output a signal a _1.

The AND circuit 7u, when the signal a ₁ and signal a _2U are both inputted, outputs a signal a _3U.
A high-pass filter circuit 7a, an absolute value calculation circuit 7b,
The low-pass filter circuit 7c and the open-phase state detection circuit 7e perform the same processing on the current values I _V and I _W detected by the current detector 5 in the same manner as the above-described current value I _u . The duration comparison circuit 7f counts the time during which the signals a _3U , a _3V , and a _3W are input, and if any one of those times continues for a predetermined time C ₃ , the open phase detection signal is output. Output.

As described above, in the method and apparatus 7 for detecting output phase loss according to the present embodiment, by using the high-pass filter circuit 7a and the low-pass filter circuit 7c, each of the three-phase AC detected by the current detector 5 can be used. Since the offset component, the ripple component, and the noise component included in the phase current value can be removed, even if the amplitude level of the three-phase alternating current output from the inverter device is small, the output open phase can be detected reliably. it can.

The output phase loss detecting device 7 of the present embodiment
May be composed of analog circuits,
Current value and current of each phase discretized by sampling period
Operates at a fixed sampling cycle based on the command value
May be performed by digital processing. Output of this embodiment
In the power loss phase detection device 7, a low-pass filter circuit 7c is used.
Output from the absolute value detection circuit 7b.
Phase current value I_U, I_V, I _WThe absolute value I of_2U, I_2V, I_2WBut
When the output is smoothed and there is no output phase loss,
The current value used for phase detection is always above a certain level
Becomes Therefore, the output phase loss detection device 7 of the present embodiment
Is the current of each phase discretized at a fixed sampling period
Value I_U, I_V, I_WOutput phase detection based on
Also, it is possible to reliably detect an output open phase.

Further, the method and device 7 for detecting an output phase loss according to the present embodiment is used for an inverter device of an AC motor 6 such as an induction motor or a synchronous motor. The method and apparatus 7 may be used in an inverter device that supplies an AC voltage to an inductive load, such as an electromagnetic stirrer.

[0029]

The output phase loss detecting method and apparatus of the present invention have the following two effects. (1) By using the high-pass filter circuit and the low-pass filter circuit, it is possible to remove the offset component, the ripple component, and the noise component included in the detected current value of each phase. Even when the amplitude level of the phase alternating current is small, the output open phase can be reliably detected. (2) The absolute value of the current value of each phase output from the absolute value detection circuit is smoothed by the low-pass filter circuit, and the current of each phase output from the absolute value detection circuit when no output phase loss occurs. The absolute value of the value is always a value above a certain level. Therefore, the output open phase detection method and apparatus of the present invention can reliably detect output open phase even when performing output open phase detection based on the current value of each phase discretized at a fixed sampling cycle. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an inverter device using an output phase loss detection method according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an output phase loss detection device according to an embodiment of the present invention.

FIG. 3 is a graph showing an operation of the output phase loss detection device according to the embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an inverter device using a conventional output phase loss detection method.

FIG. 5 is a block diagram showing a configuration of a conventional output phase loss detection device.

FIG. 6 is a graph showing a waveform of a current output from an absolute value detection circuit in a conventional output phase loss detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current control circuit 2 Coordinate converter 3 PWM generation circuit 4 Power converter 5 Current detector 6 AC motor 7, 17 Output open phase detection device 8 Inverter protection circuit 7a High pass filter circuit 7b Absolute value calculation circuit 7c Low pass filter circuit 7d Missing Phase state detection circuit 7e Operation state comparison circuit 7f Duration comparison circuit 7k AND circuit group 7u, 7v, 7w AND circuit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryuichi Oguro 2-1 Kurosaki Castle Stone, Yawata Nishi-ku, Kitakyushu-shi, Fukuoka F-term (reference) 5G058 BB01 BC01 BC02 BC16 CC04 5H007 AA06 BB06 CB05 DA05 DB02 DC02 EA02 FA13 GA08 5H740 BA01 BA11 BB05 BB08 MM11

Claims (7)

[Claims] An offset component contained in a current value of each phase of a three-phase alternating current output from an inverter device is removed by high-pass filter means, and each of the phases from which the offset component has been removed by the high-pass filter means. The absolute value of the current value of each phase is obtained, and the absolute value of the current value of each phase is smoothed by low-pass filter means. When the current command value output from the host device is larger than a first predetermined value, the low-pass filter An open phase is detected when a state where the absolute value of any one of the current values of the respective phases smoothed by the means is smaller than a second predetermined value is continued for a predetermined time. Output phase detection method to judge. 2. High-pass filter means for inputting a current value of each phase of the three-phase alternating current output from the inverter device and outputting a current value of each phase from which an offset component has been removed; An absolute value detecting means for inputting the output current value of each phase and outputting the absolute value of the current value of each phase, and an absolute value of the current value of each phase output from the absolute value detecting means A low-pass filter for smoothing and outputting the absolute value of the current value of each phase; and an operation for outputting a first signal when a current command value input from a higher-level device is larger than a first predetermined value. Comparing the absolute value of the current value of each phase outputted from the low-pass filter means with a second predetermined value, and outputting the second signal of each phase from the low-pass filter means; Absolute value of the current value of each phase An open-phase state detecting means for outputting a second signal of a phase smaller than a second predetermined value; and, when the first signal is being output, a second signal of the third signal of each phase. ANDing means for outputting a third signal of a phase in which the signal is being output; and, when output of any one of the outputs of the third signals is continued for a predetermined time, a phase loss occurs. And a duration comparing means for outputting an open phase detection signal upon determining that the output has been detected. 3. An output phase loss detection device according to claim 2, wherein each of said means is constituted by an analog circuit. 4. The output open phase detecting device according to claim 2, wherein each of the means operates at the constant sampling cycle based on the three-phase AC current discretized at a constant sampling cycle and the current command. . 5. An inverter device for driving an induction motor, comprising an output phase loss detection device according to claim 2. Description: 6. An inverter device for driving a synchronous motor, comprising the output open-phase detecting device according to claim 2. Description: 7. An inverter device for supplying an AC voltage to an inductive load comprising the output open-phase detecting device according to claim 2. Description: