JP3633564B2 - Inverter device for induction machine drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inverter device for driving an induction machine that drives an induction motor.
[0002]
[Prior art]
As a conventional induction machine driving inverter device, for example, an inverter device having a configuration shown in FIG. 7 has been proposed.
The inverter device includes an inverter 2 in which semiconductor switching elements such as four transistors are connected to a DC power source 1 in an H-bridge shape, a single-phase induction motor 3 connected to output terminals t _O1 and t _O2 of the inverter 2, The filter circuit 6 includes a reactor 4 and a capacitor 5 connected between the output terminals t _O1 and t _O2 and the single-phase induction motor 3.
[0003]
The inverter 2 includes two switching elements Q1 and Q2 connected in series to the DC power source 1, two switching elements Q3 and Q4 connected in parallel with the switching elements Q1 and Q2, and clear switching elements Q1 to Q4. Are connected in reverse parallel to each other, the output terminal t _O1 is derived from the connection point of the switching elements Q1 and Q2, and the output terminal t _O2 is derived from the connection point of the switching elements Q3 and Q4. Have a configuration.
[0004]
The control circuit 7 supplies control pulse signals G1 to G4 for on / off control of the switching elements Q1 to Q4 to the gates of the switching elements Q1 to Q4 of the inverter 2. Here, the control circuit 7 includes an operation processing unit 8 and a control pulse generation unit 9. When an operation command is input to the operation processing unit 8, the output voltage command value V 0 ^* that increases from “0” to the rated voltage command value over a certain period is output from the operation processing unit 8 to the control pulse generation unit 9. The control pulse generator 9 generates control pulse signals G1 to G4 based on the input output voltage command V0 ^* , and outputs this to the inverter 2. Further, when a stop command is input to the operation processing unit 8, a stop signal P _OFF is output from the operation processing unit 8 to the control pulse generation unit 9. When the stop signal P _OFF is input, the control pulse generator 9 outputs all the control pulse signals G1 to G4 at the off level, and stops the inverter 2.
[0005]
The control pulse signals G1 and G2 output from the control pulse generator 9 are alternately turned on with a so-called dead time when both are turned off. Similarly, the control pulses G3 and G4 have a dead time when both are turned off. It is controlled to be turned on alternately. Therefore, when the control pulse signals G1 and G4 are on, the inverter output V1 has a positive voltage + Vd, and when the control pulse signals G2 and G3 are on, the inverter output V1 has a negative voltage -Vd. At other times, 0V is output to the inverter output V1.
[0006]
As a result, by supplying the control pulse signals G1 to G4 shown in FIGS. 8A to 8D from the control circuit 7 to the inverter 2, the output voltage V1 of the inverter 2 is positive or negative as shown in FIG. 8D. Is supplied to the filter circuit 6 and converted into a smooth alternating current I1 as shown in FIG. 8 (f), so that the terminal voltage Vo of the single-phase alternating current induction machine 3 is as shown in FIG. As shown in (g), it becomes a single-phase AC voltage.
[0007]
[Problems to be solved by the invention]
However, in the above-described conventional inverter device for driving an induction machine, when the inverter 2 is stopped, the induction machine that has been operating as an electric motor operates as a generator. If the inverter 2 is restarted in this state, an excessive current flows through the inverter 2 due to the potential difference between the power generation voltage of the induction machine and the output voltage of the inverter, and the device stops abnormally or in the worst case, the device is damaged. There is a problem.
[0008]
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and can be used to safely and reliably restart the inverter when the inverter is restarted after being stopped. It is an object to provide an inverter device for machine drive.
[0009]
[Means for solving the problems]
To achieve the above object, an inverter device for driving an induction machine according to claim 1 includes an inverter that supplies an AC voltage to the induction motor, and a filter circuit including a capacitor interposed between the inverter and the induction motor; in the induction motor drive inverter device including a control circuit for controlling the output voltage of the inverter, the control circuit, when stopping the inverter, by the capacitor Nde narrow down the output voltage of the inverter to zero volts A voltage narrowing means for suppressing the power generation operation is provided.
[0010]
In the invention according to claim 1, the power generation operation of the induction machine is performed by the action of the rotational energy of the induction machine load and the magnetic flux inside the induction machine, and if any one of them disappears, the induction machine does not perform the power generation operation. When the inverter stops, the induction machine that was operating as a motor operates as a generator, but when the filter capacitor and the induction machine are connected in parallel on the output side of the inverter, The generated current, that is, the stator current flowing out from the induction machine flows only to the filter capacitor connected to the output terminal of the inverter, and thus becomes an ineffective current for the induction machine that performs the power generation operation. For this reason, the stator current is not rapidly attenuated, and the power generation operation is continued by the action of the magnetic flux created by the stator current in the induction machine and the rotational energy of the induction machine load, and the induced voltage of the induction machine is not rapidly attenuated.
[0011]
In order to quickly attenuate the induction voltage of the induction machine, it is effective to set the magnetic flux in the induction machine to “0”, that is, to set the induction machine terminal voltage to 0 V when the inverter is stopped. This is possible by narrowing down the inverter output voltage to 0 V with the narrowing means and regenerating the generated power to the DC voltage source by the potential difference between the generated voltage and the inverter output voltage.
[0012]
According to a second aspect of the present invention, there is provided an inverter device for driving an induction machine comprising: an inverter that supplies an AC voltage to the induction motor; a filter circuit that includes a capacitor interposed between the inverter and the induction motor; and an output voltage of the inverter. in the induction motor drive inverter device including a control circuit for controlling the control circuit, when stopping the inverter to suppress voltage generation operation by the capacitor output voltage Nde narrow down to zero volts of the inverter It is characterized by comprising a narrowing means and a short-circuit processing means for short-circuiting the inverter output when the output voltage narrowing is completed by the voltage narrowing means.
[0013]
In the invention according to claim 2, when the inverter is stopped, the output of the inverter is short-circuited by the short-circuit processing means, and the generated voltage of the induction machine is consumed by the resistance component of the main circuit of the inverter. It can be quickly attenuated.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a first embodiment of the present invention. Similarly to the above-described conventional example, an inverter 2 comprising an H bridge with four semiconductor switching elements Q1 to Q4 is connected to a DC power source 1, A single-phase induction motor 3 is connected to the output terminals t ₀₁ and t ₀₂ of the inverter 2 via a filter circuit 6.
[0015]
In the present embodiment, as shown in FIG. 1, the control circuit 7 that controls the inverter 2 includes an operation processing unit 8 and a control pulse generation unit 9 to which an operation command and a stop command are input. A multiplier 11 that supplies a multiplication value obtained by multiplying the output voltage command V0 ^* to be output by an attenuation coefficient K to the control pulse generation unit 9 and a stop signal P _OFF output from the operation processing unit 8 are input. When P _OFF is in the off state, the attenuation coefficient K is set to “1” and output to the multiplier 11, and when the stop signal P _OFF is in the on state, the attenuation coefficient K is changed from “1” to “0”. A voltage narrowing unit 12 that outputs a pulse-off command P _OFF1 to the control pulse generation unit 9 when the attenuation coefficient K is gradually reduced to “0” is provided.
[0016]
The voltage narrowing unit 12 executes, for example, the voltage narrowing process shown in FIG. 2 as a timer interrupt process every predetermined time. In this voltage narrowing process, first, in step S1, it is determined whether or not the stop signal P _OFF output from the operation processing unit 8 is in an on state. When this is in an off state, the process proceeds to step S2. The attenuation coefficient K is set to “1”, and then the process proceeds to step S3, the set attenuation coefficient K is output to the multiplier 11, the timer interruption process is terminated, and the process returns to the predetermined main program.
[0017]
When the determination result in step S1 is that the stop signal P _OFF is in a state, the process proceeds to step S4, and a value obtained by subtracting a preset decrease ΔK from the current attenuation coefficient K is calculated as a new attenuation coefficient K. Then, the process proceeds to step S5, where it is determined whether or not the attenuation coefficient K has become “0”. If K> 0, the process proceeds to step S3 as it is, and if K = 0, the process proceeds to step S6. After the stop signal P _OFF1 is output to the control pulse generator 9, the process _proceeds to step S3.
[0018]
Next, the operation of the first embodiment will be described.
When an operation command is input to the operation processing unit 8 of the control circuit 7, an output voltage command V0 ^* corresponding to the operation command is output from the operation processing unit 8 to the multiplier 11, and the stop signal P _OFF is turned off. By being controlled, the voltage narrowing unit 12 shifts from step S1 to step S2, thereby setting the attenuation coefficient K to “1”, which is output to the multiplier 11 in step S3.
[0019]
Therefore, the multiplier 11, by multiplying the damping coefficient K "1" to the output voltage command V0 ^*, by outputting the output voltage command V0 ^* equal output voltage command V1 ^* to the control pulse generator 9 The control pulse generator 9 generates the control pulse signals G1 to G4 shown in FIGS. 3A to 3D in the same manner as the conventional example described above, and outputs them to the semiconductor switching elements Q1 to Q4 of the inverter 2. To do.
[0020]
For this reason, the output voltage V1 shown in FIG. 3 (e) is output from the output terminals _t01 and _{tO2 of} the inverter 2, and this is supplied to the filter circuit 6, whereby the smooth alternating current shown in FIG. I1 is formed, and this is shunted to the filter capacitor 5 and the single-phase induction motor 3. As a result, the terminal voltage V0 of the single-phase induction motor 3 becomes an AC voltage whose phase is advanced from the AC current I1, as shown in FIG. 3G, and the single-phase motor 3 is rotationally driven.
[0021]
From this state, when a stop command is input to the operation processing unit 8 at the time t1, the operation processing unit 8 outputs an on-state stop signal P _OFF to the voltage narrowing processing unit 12. In the voltage narrowing processing unit 12, when the stop signal P _OFF is turned on, the process proceeds from step S1 to step S4, and a new attenuation coefficient K in which the attenuation coefficient K is decreased by the decrease amount ΔK is calculated. When this is output to the multiplier 11, the multiplier 11 multiplies the output voltage command V 0 ^* output from the operation processing unit 8 by the attenuation coefficient K, thereby outputting a value smaller than the output voltage command V 0 ^*. The voltage command V1 ^* is calculated and output to the control pulse generator 9.
[0022]
Therefore, the duty ratio of the control pulse signal G1~G4 outputted from the control pulse generator 9 (on period / off period) by approaching 1 is outputted from an output terminal t ₀₁ and t ₀₂ of the inverter 2 the potential difference between the duty ratio is also 3 gradually decreases from the rated voltage value (e), the output voltage V1 and the terminal voltage V ₀ which single-phase induction motor 3 from the inverter 2 in the output voltage V1, the induction motor By regenerating the generated power of 3 to the DC power source 1, the internal magnetic flux of the induction motor 3 is set to “0”, the power generation operation is suppressed, and the terminal voltage of the induction motor is quickly reduced to 0V as shown in FIG. It can be.
[0023]
When the attenuation coefficient K becomes “0”, the output voltage command V1 ^* output from the multiplier 11 also becomes “0”. At this time, the stop signal P _OFF1 is output from the voltage narrowing processing unit 12 to the control pulse generation unit 9. The control pulse signals G1 to G4 are controlled to be turned off.
Thereafter, when the operation command is input again to the operation processing unit 8, the output voltage command V0 ^* is output to the multiplier 11 and the stop signal P _OFF is turned off. When the “1” attenuation coefficient K is output to the multiplier 11 and the stop signal P _OFF1 is turned off, the control pulse generator 9 shifts from step S11 to step S12, and the input output voltage command V1 ^* is input ^. The control pulses G1 to G4 corresponding to the above are generated and output to the inverter 2, whereby the output voltage V1 is output from the inverter 2 and the single-phase induction motor 3 is restarted. At this time, since the terminal voltage V _{0 of} the single-phase induction motor 3 is 0V, the inverter can be restarted safely and reliably without excessive current flowing through the inverter 2.
[0024]
As described above, according to the first embodiment, when the operation is stopped, the voltage narrowing processing unit 12 narrows the output voltage of the inverter 2, thereby suppressing the power generation operation of the induction machine. An excessive current flowing in the inverter device caused by a potential difference between the generated voltage of the induction motor 3 and the output voltage of the inverter 2 at startup can be reliably prevented.
[0025]
In the first embodiment, the case where the multiplier 11 is used to gradually decrease the output voltage command V0 ^* has been described. However, the present invention is not limited to this, and the output voltage command V0 ^{* is} predetermined from the output voltage command V0 ^*. A value obtained by reducing the decrease amount ΔV0 may be calculated as a new output voltage command V0 ^* .
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0026]
In the second embodiment, the inverter 2 is short-circuit controlled after the inverter output is reduced to 0V.
That is, in the second embodiment, as shown in FIG. 4, except that the control pulse generator 9 of FIG. 1 in the first embodiment described above is provided with a short-circuit processing unit 13 as a short-circuit processing means. 1 have the same configuration as that of the first embodiment, the same reference numerals are given to the corresponding parts to those in FIG. 1, and the detailed description thereof will be omitted.
[0027]
Here, the control pulse generator 9 executes the control process shown in FIG. 5 as a timer interrupt process. In this control process, first, in step S11, it is determined whether or not the stop signal _POFF1 output from the voltage narrowing processing unit 9 has been turned on. When this is in the off state, the process proceeds to step S12. A pulse generation process for forming control pulse signals G1 to G4 having a duty ratio corresponding to the output voltage command V1 ^* input from the multiplier 11 is performed, and then the process proceeds to step S13, and the formed control pulse signals G1 to G4 are displayed. After outputting to each of the semiconductor switching elements Q1 to Q4 of the inverter 2, the timer interrupt process is terminated and the process returns to a predetermined main program.
[0028]
If the determination result in step S11 is that the stop signal _POFF1 is in the on state, the process _proceeds to step S14, the control pulse signals G2 and G4 are set in the on state, and the control pulse signals G1 and G3 are in the off state. After performing the short-circuit process set to, the process proceeds to step S13.
In the process of FIG. 5, the processes of steps S11, S13, and S14 correspond to the short circuit processing unit.
[0029]
Next, the operation of the second embodiment will be described.
In a state in which the operation command is input to the operation processing unit 8, the output voltage command V0 ^* is output from the operation processing unit 8 to the multiplier 11, and at this time, the stop signal P _OFF is in the OFF state. damping coefficient K from the processing unit 12 "1" by being output to the multiplier 11, the output voltage command V0 ^* equal output voltage command V1 ^* is input to the control pulse generating unit 9.
[0030]
In this control pulse generation unit 9, since the stop signal _POFF1 output from the voltage narrowing processing unit 12 is in an off state, the process _proceeds from step S11 to step S12, and the output voltage command V1 input from the multiplier 11 is detected. ^The control pulse signals G1 to G4 shown in FIGS. 6 (a) to 6 (d) corresponding to ^* are generated and output to the semiconductor switching elements Q1 to Q4 of the inverter 2 to generate the control pulse signals G1 to G4. The output voltage V1 shown in (e) is output, and the alternating current I1 shown in FIG. 6 (f) is shunted between the filter capacitor 5 and the single-phase induction motor 3 in response to this.
[0031]
At this time, as shown in FIG. 6G, the terminal voltage V ₀ of the induction motor 3 becomes an AC waveform having a predetermined amplitude and a phase advanced from the AC current, and thereby the induction motor 3 is rotationally driven.
When a stop command is input from the rotational drive state of the induction motor 3 to the operation processing unit 8, the attenuation coefficient K is changed from “1” to “0” in the voltage narrowing processing unit 12, as in the first embodiment. As a result, the terminal voltage V ₀ of the induction motor 3 is reduced to 0V.
[0032]
Thereafter, when the attenuation coefficient K becomes “0” and the stop signal P _OFF1 is output from the voltage narrowing processing unit 12 to the control pulse generation unit 9, the control pulse generation unit 9 starts from step S11 in FIG. In step S14, the control pulse signals G2 and G4 are set to an on state, the control pulse signals G1 and G3 are set to an off state, and output to the inverter 2 so that the output of the inverter 2 is converted to a semiconductor. Shorted through switch elements G2 and G4.
[0033]
In this case, when the terminal voltage V ₀ which single-phase induction motor 3 is positive, and conducting the semiconductor switching element Q2 and the diode D4, when the terminal voltage V ₀ is negative, and a diode D2 and a semiconductor switching element Q4 A short-circuit current flows by conducting. For this reason, the generated energy generated in the single phase induction motor 3 is consumed as heat loss due to the resistance component of the short circuit, and the terminal voltage V ₀ of the single phase induction motor 3 can be quickly attenuated to 0V.
[0034]
Thereafter, when the operation command is input again to the operation processing unit 8, the output voltage command V0 ^* is output to the multiplier 11 and the stop signal P _OFF is turned off. When the attenuation coefficient K of “1” is output to the multiplier 11 and the stop signal P _OFF1 is turned off, the control pulse generator 9 shifts from step S11 to step S12, and the input output voltage command V1 is input. By generating control pulses G1 to G4 corresponding to ^* and outputting them to the inverter 2, the output voltage V1 is output from the inverter 2, and the single-phase induction motor 3 is restarted. At this time, since the stator current of the single-phase induction motor 3 is 0 A and the output voltage V ₀ is 0 V, the inverter can be restarted safely and reliably without excessive current flowing through the inverter 2. .
[0035]
As described above, according to the second embodiment, the power generation operation of the single-phase induction motor 3 can be reliably stopped by the inverter output voltage narrowing operation and the inverter output short-circuit control when the induction motor is stopped. Further, it is possible to more reliably prevent an excessive current flowing in the inverter 2 that is generated due to a potential difference between the generated voltage of the single-phase induction motor and the output voltage of the inverter 2.
[0036]
In the second embodiment, the case where the short circuit is formed by turning on the semiconductor switching elements Q2 and Q4 of the inverter 2 is not limited to this. Even if the semiconductor switching elements Q1 and Q3 and the diodes D1 and D3 form a short circuit by controlling the Q1 and Q3 to be on and the semiconductor switching elements Q2 and Q4 to be off, the same as above. The effect of this can be obtained.
[0037]
Further, in the second embodiment, the case where the short circuit is configured by using the semiconductor switching elements configuring the inverter 2 has been described. However, the present invention is not limited to this, and the output terminal t of the inverter 2 is separately provided. it may be connected to a short circuit between _O1 and t _O2.
[0038]
【The invention's effect】
As described above, according to the first aspect of the invention, when the inverter is stopped, the inverter output voltage is narrowed down to 0 V by the voltage narrowing means, so that the potential difference between the inverter output voltage and the generated voltage of the induction machine The generated power is regenerated to the DC power supply, the magnetic flux inside the induction machine can be set to “0”, and the power generation operation of the induction motor is suppressed, so that it is safe and reliable without being affected by the generated voltage of the induction motor. The effect that the inverter can be restarted is obtained.
[0039]
According to the invention of claim 2, the inverter output voltage is narrowed down to 0V by the voltage narrowing means when the inverter is stopped, and the inverter output is short-circuited by the short-circuit processing means when the narrowing is completed. In addition to the effect of the invention according to item 1, by short-circuiting the inverter output, the power generation energy of the induction motor can be consumed as heat loss due to the resistance component of the short circuit, and the power generation operation of the induction motor can be reliably suppressed. Thus, there is an effect that the inverter can be restarted safely and reliably without being affected by the generated voltage of the induction motor.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of the present invention.
FIG. 2 is a flowchart illustrating an example of a voltage narrowing processing procedure of the voltage narrowing circuit according to the first embodiment.
FIG. 3 is a time chart showing signal waveforms at various parts for explaining the operation of the first embodiment;
FIG. 4 is a configuration diagram showing a second embodiment of the present invention.
FIG. 5 is a flowchart illustrating an example of a control processing procedure of a control pulse generation unit in the second embodiment.
FIG. 6 is a time chart showing signal waveforms of respective parts for explaining the operation of the second embodiment.
FIG. 7 is a block diagram showing a conventional example.
FIG. 8 is a time chart showing signal waveforms at various parts for explaining the operation of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 DC voltage source 2 Inverter Q1-Q4 Semiconductor switching element D1-D4 Diode 3 Single phase induction motor 4 Reactor 5 Capacitor 6 Filter circuit 7 Control circuit 8 Operation processing part 9 Control pulse generation part 11 Multiplier 12 Voltage narrowing-down processing part 13 Short-circuit processing section

Claims (2)

In an inverter apparatus for driving an induction machine, comprising: an inverter that supplies an alternating voltage to an induction motor; a filter circuit that includes a capacitor interposed between the inverter and the induction motor; and a control circuit that controls an output voltage of the inverter. ,
Wherein the control circuit, when stopping the inverter, for the induction motor drive, characterized in that it comprises a voltage narrowing means suppress the power generation operation by the capacitor output voltage Nde narrow down to zero volts of the inverter Inverter device. In an inverter apparatus for driving an induction machine, comprising: an inverter that supplies an alternating voltage to an induction motor; a filter circuit that includes a capacitor interposed between the inverter and the induction motor; and a control circuit that controls an output voltage of the inverter. ,
Wherein the control circuit, when stopping the inverter, and suppressing voltage narrowing means the power generating operation by the capacitor Nde narrowing down the output voltage to zero volts of the inverter, the narrowing of the output voltage at the voltage narrowing means An inverter device for driving an induction machine, comprising: short-circuit processing means for short-circuiting the inverter output at the time of completion.

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