JPH04138064A - Controller for current type inverter - Google Patents

Abstract

PURPOSE:To suppress vibrations of a current and a voltage generated at the output side of an inverter by detecting the amplitude or phase of an AC current supplied to a load, and correcting an output current command value with respect to an amplitude command value. CONSTITUTION:Load currents of U-, V-and W-phases are converted to two phases by a 3-phase/2-phase converter 29. Further, a sine wave of a sine wave generator 30 is applied to a coordinates converter 31, and an amplitude component Ia of a load current and a deviation (theta1-theta0) of a load current phase theta1 to an output current phase command value theta0 are calculated through an amplitude.phase detector 32. When the load current phase component (theta1-theta0) is increased, the value theta0 is corrected in a direction for reducing the phase theta1, while when the component (theta1-theta0) is decreased, the value theta0 is corrected in a direction for increasing the phase theta1. Thus, the vibrations of the current and the voltage generated at the output side of an inverter can be suppressed.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention smoothes the output current of a DC power supply with a DC reactor, converts the obtained DC current into AC current with an inverter, and It relates to current source inverters that smooth the output voltage with a capacitor and supply it to an inductive load, in particular:
The present invention relates to a control device that suppresses vibration phenomena caused by capacitors and load actance.

(Prior Art) FIG. 3 is a block diagram showing the configuration of a conventional current source inverter control device shown together with a main circuit. In the same figure, a DC power supply 1 is connected to the DC side of the Inno
3 is connected.

Moreover, capacitors 9 to 11 for smoothing the output voltage are connected to the AC side of the inverter 7, and a load 12 having reactance is also connected.

Among these, an amplitude modulation circuit 16 is provided to control the DC power supply 13, and the amplitude command value of the inverter output current is
is the phase command value θ of this inverter.

The output current command value of the DC power supply 13 is amplitude-modulated by ■.

occurs. This output current command value Ir is added as one input of the adder 18. Further, the current detector 19 detects the output current of the DC power supply 13, and the current detection value l
is added as the other input of the adder 18.The adder 18 converts the detected current value 1 from the current command value I.
Subtract 1 and output the current deviation value ΔI. Then, the current control circuit 20 controls the DC power supply 1 according to this current deviation value ΔI.
Control 3.

On the other hand, in order to control the inverter 7, a phase command value θ is used.

is added to one input of the adder 22, and the feedback value θr of the output current phase is added to the other input of the adder 22. The adder 22 subtracts the feedback value θr from the phase command value θ and outputs a phase deviation value Δθ. The integrator 23 integrates this phase deviation value Δθ, outputs an integrated phase deviation value θ, and applies it to the switching control circuit 24. This switching control circuit 24 controls the inverter 7 every time the phase deviation integral value θ reaches a certain value, and also controls the inverter 7.
Adder 2 uses the output current phase value as the feedback value θf.
In addition to 2.

FIG. 4 is a detailed operational explanatory diagram of the control device for this current source inverter, in which (a) shows the U-phase output current 1u at point A on the output side of the inverter 7 - the U-phase at point B supplied to the load 12. Load current ILU and UV between point B and point 0
A diagram showing the relationship between line voltage v and ■, (b) is current command value I
and current detection value! , (c) is the phase command value θ. (d) is a diagram showing changes in the phase deviation integral value θ, and (e) is a diagram showing the deviation of the amplitude component I of the load current with respect to the amplitude command value ■ (described later). Ia-1,), and a phase command value θ of the phase component θ of the load current, which will be described later. 2 is a diagram showing changes in deviation (θ1−θ.) with respect to

Here, as shown in FIG. 4(b), the current command value ■, which increases in a strip shape at time t11, is "51n() for every π13 of the phase command value θ shown in FIG.
θ ) [θ. −π/3 to 2π/3]. This current command value ■ and the current detector 19
The current control circuit 20 controls the DC power supply 13 so that the detected current value Ir coincides with the detected current value Ir.

Further, the output current phase value determined by the switching state of the inverter 7, that is, the phase feedback value θr shown in FIG.
"1" indicates a state where switching elements 1 and 6 are on, "2" indicates a state where switching elements 1 and 2 are on, and a state where switching elements 3 and 2 are on. "3" indicates the state where switching elements 3 and 4 are on, "4" indicates the state where switching elements 5 and 4 are on, "5" indicates the state where switching elements 5 and 4 are on, and "5" indicates the state where switching elements 5 and 6 are on. 6".

In this case, the phase command value θ. When is zero, the output current phase value θ
is also zero, and the phase command value θ. When θ increases, a deviation occurs between the output current phase value θ and the output current phase value θ.

This deviation is detected by an adder 22 and integrated by an integrator 23. Therefore, the phase deviation integral value θ 2 increases as shown in FIG. 2(d), and when it reaches a constant value on the positive side at time ti, the switching control circuit 24 advances the switching state of the inverter to "1". As a result, the phase deviation integral value θ 2 decreases, and when it reaches a constant value on the negative side at time T2, the switching control circuit 24 returns the switching state of the inverter 7 to “0”. Furthermore, by returning the switching state to "0", the phase deviation integral value θ increases, and when it reaches a constant value on the positive side at time t3, the switching state of the inverter 7 is changed to "1" again by the switching control circuit 24. You can proceed to

Similar switching control is performed thereafter. After advancing the switching state to "1" at time t4, when the phase deviation integral value θ reaches a constant value on the positive side at time t5, the switching control circuit 24 controls the switching of the inverter 7. The state is advanced to "2". In this way, the output current phase value θ is the phase command value θ. is controlled to follow.

On the other hand, the current at point A on the output side of inverter 7, that is,
The U-phase output current 1u shown in FIG. 4(a) is the current detection value I
amplitude equal to and phase command value θ.

The pulse width control waveform has a phase that matches the output current phase value θ, which is controlled to follow. When viewed from point B, the inverter 7 is connected to the load 12 by the U shown in FIG. 4(a).
A phase load current ■LIJ is supplied, and furthermore, a UV line voltage vUv shown in FIG. 3A is generated between point B and point 0.

(Problem to be Solved by the Invention) The above current source inverter has a capacitor 9 to
The capacitors 9 to 11 and the load 12 may form a resonant circuit. At this time, the deviation (I) of the amplitude component (2) of the load current with respect to the amplitude command value (6).

1) and the deviation (θ1-θ.) of the phase component θ1 of the load current with respect to the phase command value θ change as shown in FIG. 4(e). Therefore, the U-phase load current lL
The waveforms of the U and UV line voltages Vu oscillate as shown in FIG. 4(a).

Such voltage and current oscillations are attenuated by resistance in the circuit, but this poses a problem in that it becomes an obstacle to load current control and also causes an increase in loss due to harmonics. Also,
When an AC motor is connected as a load, there is also the problem that vibration and noise are generated due to torque pulsation.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a control device for a current source inverter that can suppress vibrations in current and voltage generated on the output side of the inverter.

[Structure of the invention]

(Means for Solving the Problems) This invention amplitude-modulates the amplitude command value of the output current of an inverter with the phase command value of the output current of the inverter to obtain the current command value of the DC power supply, and obtains the current command value of the DC power supply. a first control unit that controls the DC power supply so that the detected value of the output current of the DC power supply becomes equal; and a first controller that controls the inverter so that the phase command value and the phase feedback value of the output current of the inverter become equal a second control unit that controls, detects the amplitude or phase of the alternating current supplied to the load, and corrects the output current command value so as to suppress a change in the deviation of the amplitude from the amplitude command value; Alternatively, the apparatus further includes a command value correction section that corrects the amplitude command value so as to suppress a change in the phase with respect to the phase command value.

Another invention is to obtain a current command value of a DC power supply by amplitude modulating an amplitude command value of an output current of an inverter with a phase command value of the output current of this inverter, and to combine this output current command value with an output current of the DC power supply. a first control unit that controls the DC power supply so that the detected values are equal; and a second control unit that controls the inverter so that the phase command value and the phase feedback value of the output current of the inverter are equal. and detecting the amplitude and phase of the alternating current supplied to the load, correcting the output current command value so as to suppress changes in the deviation of the amplitude from the amplitude command value, and determining the phase command value of the phase. and a command value correction section that corrects the amplitude command value so as to suppress a change in the amplitude command value.

(Function) In this invention, the amplitude or phase of the alternating current supplied to the load is detected, and the output current command value of the DC power supply is corrected so as to suppress the change in this amplitude with respect to the amplitude command value, or Since the amplitude command value of the output current is corrected so as to suppress the change in this phase with respect to the phase command value, it is possible to suppress vibrations in the current and voltage that occur on the output side of the inverter.

Further, by correcting both the output current command value of the DC power supply and the amplitude command value of the output current of the inverter, it is possible to further quickly reduce the vibrations in the current and voltage that occur on the output side of the inverter.

(Embodiment) FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 3 indicate the same elements. Here, an adder 17 is provided between the amplitude modulation circuit 1B and the adder 18, so that the current command value l can be corrected by the vibration suppression component, and the adder 2
An adder 21 is provided before the phase command value θ. can be corrected with vibration suppression components.

On the other hand, in order to generate a vibration suppression component and an amplitude suppression component, a current detector 26 detects the load current of each phase of U, V, and W.
28 are provided, and each detected value is applied to a three-phase to two-phase converter 29. The three-phase two-phase converter 29 converts the three-phase load current into two-phase and outputs it. Also, the phase command value θ. A sine wave generator 30 is provided which inputs the signal and converts it into a two-phase unit sine wave, and applies this unit sine wave to a coordinate converter 31. The coordinate converter 31 uses this unit sine wave to convert the two-phase load current into a value on the rotation coordinate. This coordinate converter 31
An amplitude/phase detector 32 is connected to the output current command value θ for the amplitude component I of the load current and the load current phase θ1.
The deviation (θ1 - θ.) with respect to is calculated.

Further, the amplitude component I and the amplitude command value ld are sent to an adder 34.
The adder 34 calculates (Ia-1d) and adds the deviation of the amplitude component I from the amplitude command value Id to the change rate detector 35. The change rate detector 35 detects the amplitude deviation (
1a-1d) are calculated and added to the adder I7 as an amplitude suppression component. Furthermore, the phase deviation (θ1−θ.

) is added to the change rate detector 38, where the time change rate is calculated, and this time change rate is added to the adder 21 as a phase suppression component.

Note that in this embodiment, the amplitude modulation circuit 1B, the adder 1
8. The current detector 19 and the current control circuit 20 correspond to the first control section of the present invention, the adder 22, the integrator 23 and the switching control circuit 24 correspond to the second control section of the present invention, and , newly loaded adder 17, adder 21,
The current detectors 26 to 28, the three-phase two-phase converter 29, the sine wave generator 30, the coordinate converter 3L, the amplitude/phase detector 32, the adder 34, the rate of change detector 35, and the rate of change detector 38 are according to the present invention. It corresponds to the command value correction section.

The operation of this embodiment configured as described above will be described below with reference to FIG. 2, focusing on the parts that are different in configuration from the conventional device.

When the amplitude of the load current is 11 and the phase is 01, the current detectors 26 to 28 detect currents expressed by the following equations.

i −15in(θl) a i =I 5in(θt −π/8) ai −Summer 5in(θ1−2 π13)
...(1)a Therefore, the three-phase two-phase converter 29 calculates the following equation 1, %, and outputs the value shown by the following equation.

i −15in(θl) ai −15in(θ1−π/2) a −−Icos(θ1) (3) The sine wave generator 30 outputs the output current phase command value θ. Input and output the value shown by the following formula.

A-sin(θ0) B--CO8(θ.) ...(4)
Then, the coordinate converter 31 outputs the current value of the following formula % formula % by performing the following calculation converted into the rotational coordinate.

i −15in(θl−θ0) AOa i−−1cos(θl−00) BOa (6) Based on these values, the amplitude/phase detector 32 is calculated using the following formula (% formula%)
) to calculate the amplitude component of the load current.

Based on these values, the amplitude/phase detector 32 further determines the output current phase command value θ of the load current phase θ1 using the following formula. The load current phase component (θ1−θ.) for the load current is calculated.

The adder 34 subtracts the amplitude command value Id from the amplitude component I, and outputs an amplitude deviation B, -Id). FIGS. 2(e) and 4(e) show changes in this amplitude deviation (1, -Id) and the load current phase component (θ1-θ.).

Now, at time t1□ in Fig. 4, the command value I of the DC current is
When increasing stepwise, the U Japanese charge current I and the UV line voltage V, V shown in Fig. 4(a) vary as shown in the figure.
Ia-1, ) and the load current phase component (θ1-θ.) oscillate as shown in FIG. 2(e).

In this embodiment, the amplitude deviation (1, -1d) is detected by the rate of change detector 3.
5 and its output is applied to the adder 17 with negative polarity. As a result, when the amplitude deviation (1°!) is increasing, the current command value is 1. and the amplitude deviation (Ia-1d
) is decreasing, the current command value I is corrected to decrease.

``In other words, when the amplitude of the load current increases relative to the command value, the output current of the DC power supply decreases, and when the amplitude of the load current decreases relative to the command value, The output current of the DC power source is controlled to increase, thereby suppressing current and voltage oscillations occurring on the output side of the inverter.

Furthermore, in this embodiment, the load current phase component (θ1−θ
0) is applied to the change rate detector 38, and its output is applied to the adder 21 with negative polarity. As a result, when the load current phase component (θ1 - θ.) is increasing, the load current phase θ1
On the contrary, the load current phase component (θ1−θ
. ) decreases, the output current phase command value θ increases in the direction in which the load current phase θ1 increases. Correct. In other words, the output current phase decreases when the phase of the load current decreases relative to the command value, and the output current phase decreases when the phase of the load current decreases relative to the command value. The inverter 7 is controlled so that the current and the voltage increase, thereby suppressing the oscillations in the current and voltage that occur on the output side of the inverter.

FIGS. 2(a) to 2(e) are waveform diagrams corresponding to FIG. 4 when vibration suppression by amplitude control of the DC current and vibration suppression by phase control of the output current are performed simultaneously. That is,
(a) shows the U-phase output current at point A on the output side of the inverter 7 lU1 U Japanese food load current I at point B supplied to the load 12
LU' and UV line voltage vU between point B and point 0
(b) is a diagram showing the relationship between current command value I and detected current value 11, (C) is a diagram showing the relationship between phase command value θ and output current phase feedback value θ1. (d) is a diagram showing the change in the phase deviation integral value θ, and (e) is a diagram showing the deviation (1, -1) of the amplitude component I of the load current with respect to the amplitude command value I, which will be described later.
d), and a phase command value θ of the phase component θ of the load current, which will be described later. It is a figure which shows the change of the deviation ((theta)1-(theta)) with respect to FIG.

As is clear from FIG. 2, even if the output current command value I is changed stepwise at time t11, the U Japanese food load current LU and the UV line voltage vUv hardly oscillate. Further, the amplitude deviation (Ia-■) and the phase deviation (θ1-θ0) are also quickly returned to zero.

In the above embodiment, vibration suppression by amplitude control of the DC current and vibration suppression by phase control of the output current were simultaneously performed, but if only one of these was performed, the result would be slightly lower than in the above embodiment. Although there is a time delay, it is possible to suppress current and voltage oscillations that occur on the output side of the inverter.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in a current source inverter that smooths the output voltage of an inverter with a capacitor and supplies it to a load having reactance, vibration phenomena due to parallel resonance between the capacitor and the load reactance are suppressed. can do.

As a result, it is possible to suppress an increase in electrical loss due to current and voltage oscillations, and it is also possible to suppress generation of vibrations and noise due to torque pulsation when an AC motor is connected as a load.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention together with the main circuit, Fig. 2 is a waveform diagram for explaining the operation of the embodiment, and Fig. 3 is a conventional current source inverter. A block diagram showing the configuration of the control device together with the main circuit, Part 4
The figure is a waveform diagram for explaining the operation of the device. 7... Inverter, 8... DC reactor, 9-1
1... Capacitor, 13... DC power supply, 1B...
Amplitude modulation circuit, 19.26-28...Current detector, 2
0... Current control circuit, 23... Integrator, 24...
Switching control circuit, 29... 3-phase 2-phase converter, 3
0... Sine wave generator, 31... Coordinate converter, 32...
...Amplitude/phase detector, 35.38... Rate of change detector.

Claims (1)

[Claims] 1. Smooth the output current of a controllable DC power supply with a DC reactor, convert the smoothed DC current into AC current with an inverter, and smooth the output voltage of this inverter with a capacitor to create a reactance. In a current source inverter that supplies a load having a current source, the amplitude command value of the output current of the inverter is amplitude-modulated by the phase command value of the output current of this inverter to obtain the output current command value of the DC power supply, and this output current command a first control unit that controls the DC power supply so that the detected value of the output current of the inverter becomes equal to a detected value of the output current of the inverter; a second control unit that detects the amplitude or phase of the alternating current supplied to the load, and corrects the output current command value so as to suppress a change in deviation of the amplitude from the amplitude command value; or a command value correction section that corrects the amplitude command value so as to suppress a change in the phase with respect to the phase command value. 2. Smooth the output current of a controllable DC power supply with a DC reactor, convert the smoothed DC current into AC current with an inverter, and smooth the output voltage of this inverter with a capacitor to supply it to a load with reactance. In a current source inverter, the amplitude command value of the output current of the inverter is amplitude-modulated by the phase command value of the output current of this inverter to obtain the output current command value of the DC power supply, and this output current command value and the output current command value of the DC power supply are A first control unit that controls the DC power supply so that the detected output current value becomes equal to the output current detection value, and a second control unit that controls the inverter so that the phase command value and the phase feedback value of the output current of the inverter become equal to each other. a control unit; detecting the amplitude and phase of the alternating current supplied to the load; correcting the output current command value so as to suppress a change in deviation of the amplitude from the amplitude command value; A control device for a current source inverter, comprising: a command value correction section that corrects the amplitude command value so as to suppress a change in the phase command value.