JPH06261585A - Inverter device - Google Patents

Abstract

PURPOSE:To provide an inverter device wherein, even when a fault is caused in the speed sensor of an AC motor, a means to emergently continue the operation of the motor until the fault is restored is provided. CONSTITUTION:In an ordinary state that the speed sensor 9 of an AC motor 8 is operated normally, an inverter 1 is controlled by a first control means 2 by using the output of the speed sensor 9. When the fault of the speed sensor or the like is detected by a fault detection means 5, a changeover circuit 4 is changed over, the output of a second control means 3 which can control the inverter 1 without using the speed sensor 9 is given to the inverter 1, and the operation of the motor is continued. By this constitution, even when the fault is caused in the speed sensor or the like, the operation of the motor can be continued emergently, and a production stop is not caused when the title device is applied to a production line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for driving a three-phase AC motor (hereinafter referred to as "ACM").
Normally, a speed sensor such as a pulse generator is used to control high precision and high speed response, and as a temporary measure when the speed sensor cannot be used due to a failure, etc., the speed sensor is not used at the expense of accuracy and response. The present invention relates to an inverter device that switches to control means and continues operation.

[0002]

2. Description of the Related Art Vector control is known as means for controlling ACM with high precision and high speed response. Most of the methods currently in practical use are of the slip frequency control type, and the basic method is the Technical Report of the Institute of Electrical Engineers of Japan (Part II) No. 109, "Technical Trends of AC Variable Speed Drive Systems", April 41, pp. 41. 79
Fig., "Inverter Application Manual", page 90, Fig. 2.71, published by Densho Shoin, September 1985,
It is described in Toyo Denki Giho No. 57 "Voltage Vector Control Inverter", issued in November, 2013, in FIG. 1 (b).

The methods described in the above documents all use a velocity sensor to detect the angular velocity ω _{m of} the ACM detected by the velocity sensor.
The separately calculated slip angular frequency ω _s (ω _s1 ) and slip compensation Δω _s are added to (ω _r ) to obtain the inverter frequency. When a high speed response is not required, for example, the "Inverter Application Manual", page 85, 2.6.
A slip frequency control as described in Figure 9 is used, which also requires a velocity sensor.

[0004]

Since the speed sensor used for these controls is a precision instrument, it is vulnerable to vibrations and shocks and is easily damaged if mishandled. Also, its life is ACM
Since it is shorter than the main body, the probability of failure is not low. Then, if the speed sensor fails, the ACM cannot be operated at all by the vector control or the slip frequency control system, and if the product is applied to the manufacturing line, the production stops.

The present invention has been made in view of the above problems, and an object thereof is to provide means for urgently continuing operation until the speed sensor of the ACM is restored even if the speed sensor fails. An object of the present invention is to provide a provided inverter device.

[0006]

In order to solve the above-mentioned problems, the present invention provides an inverter device comprising a single-phase or three-phase inverter for driving an ACM and a control means for controlling the inverter. First control means for controlling the inverter by using the output of the speed sensor for detecting the speed, second control means for controlling the inverter without using the speed sensor, and a failure for detecting a failure of the speed sensor or the like. A detecting means is provided, and during normal operation, the first control means is selected to control the inverter, and when a failure of the speed sensor or the like is detected by the failure detecting means, switching to the second controlling means is performed. Then, the inverter is configured to be controlled.

[0007]

When the speed sensor that detects the speed of the ACM is operating normally, the inverter is controlled by the first control means that controls the inverter using the output of the speed sensor. When the failure detection unit detects a failure in the speed sensor or the like, the operation is continued by switching to the second control unit that controls the inverter without using the speed sensor.

Since the present invention is configured as described above, in the normal state, the first high precision and high speed response using the speed sensor is provided.
If necessary, such as when the speed sensor fails, the operation is continued by switching to the second control means that can control the inverter without using the speed sensor, even if the accuracy and response speed are somewhat sacrificed. Therefore, even if the speed sensor or the like fails, it becomes possible to continue the operation in an emergency. Especially, when the present invention is applied to a production line, a production stop does not occur.

Further, recently, since a high-performance 1-chip microcomputer and a high-speed digital signal processor (hereinafter referred to as CPU) called DSP are available at low cost, control of the inverter device is realized by software such as CPU. It is common. Further, the program memory area is also expanding. Therefore, by incorporating both the first and second control means in the same software, the present invention can be realized without adding special hardware.

[0010]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, 1 is an inverter that converts a commercial frequency power supply voltage into an arbitrary frequency / voltage,
The operation is, for example, the "Inverter application manual" mentioned above.
Known as detailed on pages 39-78. 1a is a current detector for detecting the output current of the inverter 1, and 7 is A
Speed setter for setting the rotation speed of CM, 8 is ACM, 9
Is a pulse generator (hereinafter referred to as PG) that detects the number of rotations of the ACM.

Reference numeral 2 is a first control section for controlling the inverter 1. The first control unit 2 is a means for realizing a slip frequency type vector control of high precision and high speed response by using PG9, and its operation is as described in detail in the above "voltage type vector control inverter". is there. Reference numeral 21 denotes a vector calculation unit. In the vector calculation unit 21, 201 denotes a proportional / integral (P ^{) difference} between the speed set value N ^* output by the speed setter 7 and the rotation speed of the ACM detected by PG9.
I) Calculation and amplification, and the output is the torque current command value I
q is an ASR (speed control device), 202 is a magnetizing current setter that sets the magnetizing current component Iφ, and 203 is an ASR 201.
Torque current command value Iq and magnetizing current setter 20
2 based on the magnetizing current component Iφ output by the primary current command value I
₁ is a primary current command unit, 204 is a slip frequency command unit that obtains a slip frequency ωs based on the torque current command value Iq output by the ASR 201 and the magnetizing current component Iφ output by the magnetizing current setter 202, and 205 is output by the ASR 201. It is a transient slip frequency calculation unit that obtains the transient slip frequency Δω from the torque current command value Iq, and the difference between the primary current command value I ₁ output by the primary current command unit 203 and the output current of the inverter detected by the current detector 1a is It is given to the current regulator 207 described later. Further, the slip frequency ωs output from the slip frequency command unit 204 and the transient slip frequency calculation unit 20
The sum of the transient slip frequencies Δω output by 4 is output as the slip frequency and is added to the rotation speed signal of the ACM 8 output by PG 9 to obtain the primary frequency command value f ^* .

Reference numeral 207 is a current regulator that controls the output current of the inverter 1 to be equal to the primary current command value I ₁ and outputs the primary voltage command value V ^* . 208 is the primary voltage command value V ^* of the inverter 1. It is a PWM signal generator that generates a signal for turning on / off a switching element that constitutes the inverter 1 in a predetermined procedure based on a primary frequency command value f ^* .

3 is A without using a speed detection sensor such as PG
A second control unit that realizes variable speed drive of CM, and in the second control unit 3, 301 is a voltage command device that obtains a primary voltage command value V ^* based on the speed setting value output from the speed setting device 7, Reference numeral 302 denotes a frequency commander that obtains the primary frequency command value f ^* based on the speed set value output by the speed setter 7.
The voltage commander 301 and the frequency commander 302 are composed of function generators, and output the primary voltage command value V ^* and the primary frequency command value f ^* corresponding to the input speed setting value N ^* .

FIG. 2 is a diagram showing the characteristics of the voltage command device 301. The voltage command device 301 shows a primary voltage command as shown in the same drawing in response to a change in the speed setting value N ^* output by the speed setting device 7. Output the value V ^* . FIG. 3 is a diagram showing the characteristics of the frequency command device 302. The frequency command device 302 outputs a primary frequency command value f ^* as shown in the figure in response to a change in the speed set value N ^* .

Reference numeral 303 denotes a PWM signal for generating an on / off signal of a switching element constituting the inverter 1 based on the primary voltage command value V ^* output by the voltage command device 301 and the primary frequency command value f ^* output by the frequency command device 302. It is a generator. 4 is the output of the PWM signal generator 208 and the PWM
A switch 5 for switching the output of the signal generator 303 and outputting a PWM signal to the switching circuit of the inverter 1 is P
A PG failure detector for detecting a failure of G9 and its related circuit. The PG failure detector 5 constantly monitors the output of PG9, and when it is determined that PG9 or its related circuit has failed, or the switch 6 Is turned on, output j
₁ is generated and the output of the switching device 4 is set to the PWM signal generator 20.
The output signal of 8 is switched to the output signal of the PWM signal generator 303.

Next, the operation of this embodiment shown in FIG. 1 will be described. The ASR 201 of the first control unit 2 is connected to the speed setter 7 and P
The deviation from the feedback signal from G is proportional / integral (P
I) Amplify and use the output as the torque current component command value Iq. Torque current component command value Iq output by ASR 201
And the magnetizing current component Iφ set by the magnetizing current setting unit 202.
Is supplied to the vector calculation unit 21.

Primary current command section 20 of vector operation section 21
3 calculates √ (Iq ² + Iφ ² ) from the torque current component command value Iq and the magnetizing current component Iφ to obtain the primary current command value I ₁ . The slip frequency command unit 204 calculates (r ₂ × L ₂ ) ÷ (Iq from the secondary resistance r ₂ , the secondary inductance L ₂ of the ACM 8, the torque current component command value Iq, and the magnetizing current component Iφ.
× Iφ) to calculate the slip angular frequency ω _S. Further, the transient slip angular frequency calculation unit 205 calculates d / dt (K × Iq) from the torque current component command value Iq to obtain the transient slip angular frequency Δω _S.

Feedback from the PG9
The above slip angular frequency ω_SAnd transient slip angular frequency Δω_S
Primary frequency command to be added to the PWM generator 208
Value f ^*To get On the other hand, the current regulator (ACR) 207 is
Output current of the inverter 1 detected by the flow detector 1a
And primary current command value I₁Based on the difference between the primary voltage command value V
^*Is given to the PWM generator 208.

The PWM generator 208 operates the inverter 1 based on the primary voltage command value V ^* and the primary frequency command value f ^*.
The switching element that constitutes the ACM is turned on and off by a procedure determined by its output frequency, output voltage, etc., and a desired frequency and voltage are generated from the inverter 1,
Drive eight. Note that these procedures are, for example, “Semiconductor power conversion circuit” published by The Institute of Electrical Engineers of Japan in March 1987.
Are known as described in detail in P. 108-P.

Here, the PG failure detector 5 constantly monitors the output of the PG 9 and judges whether or not it has failed.
Alternatively, when the switch 6 is turned on, the signal j ₁ is sent to the switching device 4.
Is supplied from the PWM generator 208 to the output of the switch 4
Switch to the WM generator 303 side. The criterion for determining that PG9 has failed is, for example, when the torque current component command value Iq of the output of the ASR 201 is in a saturated state for a certain period of time or longer.

That is, when the output of the PG 9 is not output, the output of the ASR 201 is saturated in the direction in which the torque component current Iq outputs the torque on the drive side to the ACM, and conversely, noise is constantly mixed in the PG signal. Then, when the feedback amount is larger than the actual rotation speed, the output of the ASR 201 is
Since it is saturated in the direction in which the torque on the brake side is output to the ACM 8, by detecting that the torque current component command value Iq of the output of the ASR 201 is in a saturated state for a certain period of time or more,
The failure of PG9 can be detected. The detection of the failure of the PG 9 and its related circuit is not limited to the above means, and other means can be used.

Now, the first controller 2 controls the ACM 8
PG9 malfunctions while controlling the
Output 5₁Is generated, the switch 4 causes the PG failure detection
Output signal j of output device 5₁According to the PWM generator 30
Select the output on the 3 side. Voltage command device 3 of second control unit 3
01 is the speed set value N output by the speed setter 7. ^*Based on
The primary voltage command value V shown in FIG.^*Occurs, and also
The wave number commander 302 is the speed set value output by the speed setter 7.
N^*Based on the primary frequency command value f shown in FIG.^*Occurs
And the PWM signal generator 303 uses the primary voltage command
Value V^*And primary frequency command value f^*Of the inverter 1
Turn on the switching elements that make up the switching elements.
To generate the desired frequency and voltage from the inverter 1.
Let

As described above, in this embodiment,
Normally, the second control unit 3 is driven by the first control unit 2 and can drive the ACM without using the PG or the like when necessary, such as when the PG 9 or the like fails, although the accuracy and response speed are somewhat sacrificed. Since the operation is switched to and the operation is continued, even if the PG or the like breaks down, the operation can be temporarily continued, and when applied to the production line, the production is not stopped.

FIG. 4 is a diagram showing a second embodiment of the present invention. This embodiment is different from the above-mentioned first embodiment in PWM.
In this system, one generator is used and its input is switched. 4, the same components as those shown in FIG. 1 are designated by the same reference numerals, and in this embodiment, the PWM signal generator 303 is different from that of the first embodiment shown in FIG. In addition to removing only the PWM signal generator 208, two switching devices 41 and 42 are provided, and the input of the PWM signal generator 208 is switched by the output j ₁ of the PG failure detector 5. 1 and 2
The control units 2'and 3'correspond to the first and second control units 2 and 3 of the first embodiment, respectively, except that the PWM generator is omitted, and the functions of the other parts are the same as those of the first embodiment. It is the same as the example.

In FIG. 4, the first control unit 2'provides A
When the CM 8 is controlled and the PG 9 fails, and the PG failure detector 5 generates the output j ₁ , the switches 41 and 42 are switched.
Are switched, and the primary voltage command value V ^* and the primary frequency command value f ^* output by the second control unit 3 ′ are the PWM signal generator 2
08, the PWM signal generator 208 controls the inverter 1 by turning on and off the switching elements constituting the switching elements of the inverter 1 based on the primary voltage command value V ^* and the primary frequency command value f ^* .

Since only one PWM signal generator is required in this embodiment, the structure can be simplified as compared with that in the first embodiment. In the above embodiment, an example in which the slip frequency vector control is used as the first control unit 2 or 2'is shown, but the present invention is not limited to the above embodiment, and a PG or the like is used. Any control means may be used, and for example, simple slip frequency control as shown on pages 84 to 87 of the "Inverter Application Manual" may be used.

Further, the simplest V / F control method is shown for the second control units 3 and 3 ', but this may be any method as long as it can drive the ACM at a variable speed without using PG or the like.

[0028]

As described above, the first control means for controlling the inverter by using the output of the speed sensor,
When a second control means for controlling the inverter without using a speed sensor is provided and the first control device is selected during normal operation to control the inverter, and a failure of the speed sensor or the like is detected. , Switch to the second control device,
Since the inverter is configured to be controlled, the required minimum operation can be continued even if the speed sensor fails. Therefore, when the present invention is applied to, for example, a production line, a production stop does not occur, and the effect is practically extremely large.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram of input and output of the voltage command device 301 according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram of inputs and outputs of a frequency command device 302 according to the embodiment of the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

1 Inverter 1a Current detector 2,2 'First control unit 3,3' Second control unit 4,41,42 Switching device 5 PG failure detector 6 Switch 7 Speed setting device 8 AC motor 9 Pulse generator ( PG) 201 ASR 202 Magnetizing current setting device 203 Primary current command part 204 Slip frequency command part 205 Transient slip angle frequency calculation part 207 ACR 208,303 PWM generator 301 Voltage command device 302 Frequency command device

Claims (1)

[Claims] 1. An inverter device comprising a single-phase or three-phase inverter for driving an AC electric motor and control means for controlling the inverter, wherein the inverter is output by using an output of a speed sensor for detecting the speed of the AC electric motor. There is provided a first control means for controlling the above, a second control means for controlling the above-mentioned inverter without using a speed sensor, and a failure detection means for detecting a failure of the speed sensor or the like. The control means is selected to control the inverter, and when the failure detection means detects a failure of the speed sensor or the like, the inverter is switched to the second control means to control the inverter. apparatus.