JPH01214265A - Output voltage control device for current type converter device - Google Patents

Abstract

PURPOSE:To suppress the deviation of a fundamental wave power factor, by delaying the phase difference between the phase of all the igniting pulses and the phase of supply voltage by the same quantity with respect to the phase advancing current of a low-pass filter when the command value of the DC average voltage is not less than the specified value. CONSTITUTION:An igniting pulse generating circuit for three-phase current type rectifier is composed of a PWM pattern generation circuit S which comprises a sine wave pattern generation circuit 6, a short-circuit pulse generation circuit 7, a composition circuit 8, and a short-circuit pulse width command value generation circuit, a function generating circuit 17, a multiplier 18, and a regulator 19, etc. The output of the function generating circuit 17 where a DC average voltage command Ed* is inputted is multiplied by the fundamental wave power factor set value with the multiplier 18. The value thus found and the fundamental wave detected value are inputted into the regulator 19. Let the regulated output be the phase variation phi of all the igniting pulse against the supply voltage phase. In this way, the restriction of the minimum pulse width can be dispensed with up to the small DC current flow range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for controlling the output voltage of a current source converter having a bridge configuration to which a self-extinguishing element such as a GTO (gate turn-off thyristor) is applied. .

[Conventional technology]

Here, as an example of conventional technology, a three-phase flow rectifier with a bridge configuration as shown in FIG. 3 (with the low-pass filter 2 removed) will be explained.
The same can be said of single-phase current source rectifiers and the like.

In Fig. 3, 1 is a three-phase AC power supply, 2 is a low-pass filter for removing harmonics, 2 & is a filter reactor that makes up the filter, 2b is a filter capacitor that makes up the filter, and 3 is a self-extinguishing element (U, V , W, X, Y.

(6 phases of Z are shown), 4 is a DC reactor, 5 is a load, e, 1 is an output voltage (instantaneous value) of a three-phase current rectifier (current source converter), but here it is a low-pass filter. 2 is considered as not being connected.

In this ball-phase current rectifier, the nine three-phase AC voltages (U, V, W) generated from the three-phase AC power supply 1 are directly applied as there is no low-pass filter 2, and the current i of each phase is ,! 1 is inflow PU PV
ν PW. In order to control the load current id flowing to the load 5 at a constant value, it is necessary to control the output voltage e of the three-phase current rectifier so that it matches the DC average voltage E, t - its command value E. ing.

To achieve this control, the pulse width gain N (PWM control) of the ignition pulses applied to the self-extinguishing elements 3 for six phases is performed.

FIG. 4 is a block diagram showing a firing pulse generating circuit that generates and outputs such a PWM full 8 firing pulse.

In the figure, 6 is a sine wave pattern generation circuit, 7 is a short circuit pulse generation circuit, 8 is a synthesis circuit, 9 is a phase shift amount determination circuit,
10 is a short-circuit pulse width command value generation circuit, and 40 is a clock generation circuit which receives a power supply voltage and generates a clock synchronized with the power supply frequency.

Here, the phase shift amount determining circuit 9 determines that when the command value E of the DC average voltage of the three-phase current rectifier is in a range where IEdl>AC (wherein the positive constant voltage) holds true, a constant voltage is output as the phase shift amount, and the DC average voltage command [E,
It is a type of function generating circuit that outputs a phase shift amount that changes in the range of 0 to 1π (depending on the magnitude of the command value NeEd of the DC average voltage) when lEd is in the range where l<A holds true. .

Further, the short circuit pulse command value generation circuit 10 outputs a constant value when the command value Ed of the DC average voltage is in the range where IEdl<A holds true, and the command value Ed of the DC average voltage is within the range where IEdl<A holds true. >A, it is a kind of function generating circuit that outputs an amount that varies depending on the magnitude of the command value Ed of the DC average voltage.

FIG. 5 is a time chart showing an example of the waveform of each part signal in FIGS. 3 and 4 described above.

That is, FIG. 5 shows power supply voltage waveforms (U, V, W) and self-extinguishing elements 5 for six phases (U, V, W, X, Y).

In addition to the ignition pulse applied to Z) being shown as a PWM pattern, the waveforms of voltage and current at each part in FIG. 3 are shown.

The sine wave pattern generation circuit 6 and short-circuit pulse generation circuit 7 in FIG. 4 are round circuits that generate the white firing pulse (short-circuit pulse) in the PWM pattern of FIG. The outputs are combined by a combining circuit 8 to generate a final PWM pattern.

When the absolute value of the DC average voltage command [Ed is greater than or equal to the predetermined value ff1A, it is subject to the restriction of the minimum pulse width of the self-extinguishing element 3 (the minimum pulse width such that the pulse width of the output pulse cannot be made any smaller). In the range where the phase shift amount determination circuit 9 shown in FIG. The fundamental wave power factor of the rectifier is controlled to 1.
Or try to keep it at -1.

In addition, in the range where the absolute value of the DC average voltage command value E is less than a predetermined value [A and the minimum pulse width of the self-extinguishing element 3 is limited, all ignition pulse widths including short circuit pulses are fixed, The DC average voltage E is controlled by changing the output of the phase shift amount determination circuit 9 to change the phases of all firing pulse phases relative to the power supply voltage phase by the same MP.

The conventional technology explained above is published by the Institute of Electrical Engineers of Japan on 6831/1987 and compiled by the Technical Committee of the Institute of Electrical Engineers of Japan [Semiconductor Power Conversion Circuit]
It is described on pages 212 to 214 of .

[Problem to be solved by the invention]

According to the conventional technology explained above, a thyristor is applied,
Compared to previous rectifiers that only perform phase control, it is possible to significantly improve the power factor of the power supply, and the DC current is 1. Glue pull components can also be significantly reduced. In addition, when the absolute value of the DC average voltage command [Ed is less than a predetermined value A, the phase shift amount determining circuit 9 is activated to perform phase control, so that the DC average voltage Ed is set within a voltage range from positive to 0 to negative. can be controlled continuously over

However, in reality, the distortion PU flowing through the bridge input
A low-pass filter 2 is inserted between the power supply 1 and the bridge in order to prevent the harmonic components contained in the alternating current (1.1 in Figure 3) from flowing into the power supply. This shows a case where the most typical LC filter is used as the low-pass filter 2. Taking this low-pass filter 2 into consideration, in the circuit of FIG. 3, the DC current ld flowing through the load 5 is made constant. , DC average voltage E
Considering the case of controlling d, the bridge circuit, the DC reactor 4, and the load 5 in FIG. 3 can be collectively replaced isometrically with a current source that flows a distorted wave AC current input to the bridge. The equivalent circuit for the U phase is shown in FIG.

The actance 12 in this figure represents the combination of the reactance of the power source 1 and the filter reactor 2a, and the resistor 13 represents the combination of the resistance of the power source 1 and the filter reactor 2a.
It represents the composite of the resistance component of a.

Here, since we are currently focusing on the fundamental wave power factor, we will consider only the fundamental wave component 'PU(1) of the current 'PU' flowing from the equimultiplex current source 15. Further, it is assumed that the U-phase power supply voltage V U and the multiple source fundamental wave current 'PU(1) can be expressed by the following equations (1) and (2), respectively.

V1) -VU5lflωt (Vu: peak value of VU, ω: power supply angular frequency)・
・Song (1) 'pty (+do I pU (,) sin (
Cap - ψ) (Eng PU(1)"Peak value of PU(1))
・・・・・・(2) And Fig. 6 Glue accelerator 1
2 inductance, resistance 13. Letting the capacitances of the U-phase filter capacitor 14 be expressed as L, R, and C, respectively, the fundamental wave component 'U(1) of the U-phase power supply current iU is as follows.
It can be expressed as the following equation (3).

In general, R is a very small box, so (ωCR)=
tO, and ωILC (expressed as 1, so θ=
-, , θ2-0 can be approximated. Therefore, the above formula (
3) can be approximated as shown in the following equation (4).

By the way, L and C are directly used to determine the cutoff frequency of the low-pass filter, but if the switching frequency of the self-arc-extinguishing element 3 is around several hundred [-] and cannot be set very high, the bridge input is used. The distorted wave alternating current flowing through 'PH,
Since low-order harmonic components are included, it is not possible to make these corrections too small.

In this case, the above equation (4) cannot be ignored, and especially in the operating region where the peak value IPU(1) is small, 'u(1)
) is advanced by a certain amount. From this, as shown in Figure 4, the phase of the fundamental wave component of the distorted wave AC current of the bridge input with respect to the phase of the power supply voltage can be determined from only the DC average voltage command [E, without considering the low-pass filter. When a low-pass filter is connected,
Under this influence, there was a problem in that the rectifier could not be operated with a desired fundamental wave power factor.

This invention provides a current source rectifier that performs PWM control when the absolute value of the DC average voltage command [E, is larger than a predetermined value,
In a voltage range that is not limited by the minimum pulse width of the self-extinguishing element, operation can be performed at the desired fundamental wave power factor without being affected by the low-pass filter, and the absolute value of the DC average voltage command value does not exceed the specified value. Even when passing, the phase difference of the ignition pulse with respect to the power supply voltage changes continuously according to the DC average voltage command value, and can be controlled without disturbing the PWM pattern, and
It is an object of the present invention to provide an output voltage control device for a current source converter that can control the DC average voltage to zero.

[Means to solve the problem]

To achieve the above object, the present invention provides an output voltage control device for a current source converter that connects a power source to a current source converter via a high frequency removal filter and controls the output voltage of the converter, comprising: the converter. A PWM control means for controlling the ignition pulse width of the bridge-connected self-extinguishing element constituting the power supply, and a PWM control means that receives the detected value of the fundamental wave power factor of the power source and its set value and controls the power factor so that the two match. When the command value of the output voltage of the phase control means for controlling the ignition phase of the arc pulse and the converter is E, the command [Ed When there is a
The WM control means controls the ignition pulse width of the self-extinguishing element according to the magnitude of the command value Ed, and the phase control means irrespective of the magnitude of the command value E.
The ignition phase of the ignition pulse is controlled so that the detected value of the fundamental wave power factor of the power source matches its set value, and when the command value Ed is in the range where lE*l<A holds true, the above-mentioned PWMflllJ control means and the finger means E
Regardless of the magnitude of d, the ignition pulse width of the self-extinguishing element is controlled to one foot width, and the phase control means controls the input fundamental wave according to the magnitude of the command value E. The present invention is equipped with a control circuit that changes the set value of the power factor itself.

[Effect]

In the present invention, the fundamental wave power factor on the power supply side from the low-pass filter placed at the AC end of the three-phase current rectifier (conversion device) or the set value and detected value of the phase difference between the power supply voltage and the power supply current are used. , when the absolute value of the average voltage command value relative to the power supply voltage phase of the ignition pulse phase for all self-extinguishing elements is greater than or equal to a predetermined DC value, the above setting value is changed according to the positive or negative value of the DC average voltage command value. By keeping the magnitude itself at a constant value, although the sign is small, it is possible to operate at the desired fundamental wave power factor.
j When the absolute value of the DC average voltage command value is less than a predetermined value [A, the DC average voltage can be changed without disturbing the PWM pattern by changing the set value itself according to the magnitude of the DC average voltage command value. can be continuously controlled from a predetermined value A to 0.

〔Example〕

FIG. 1 is a block diagram showing a main part of an embodiment of the present invention, that is, an ignition pulse generation circuit when the present invention is applied to a three-phase current source rectifier as shown in FIG.

In FIG. 4, only the short circuit pulse width is changed in accordance with the command value from the short circuit pulse width command value generation circuit 10 when the absolute value of the DC average voltage command value Ed is equal to or greater than a predetermined value Å. Generally, it is possible to change the PWM pattern itself. Therefore, in FIG. 1, the sine wave pattern generating circuit 6. of FIG. The short-circuit pulse generation circuit 72, the synthesis circuit 8, and the short-circuit pulse width command value generation circuit 10 are combined into one and shown as a PWM pattern generation circuit S. In FIG. 4, from the DC average voltage command value Ed, the phase shift amount determining circuit 9 calculates all ignition pulse phases of 1! While the amount of phase change ψ with respect to the power supply voltage phase is determined, in FIG. The value obtained by multiplying by 18 and the fundamental wave power factor detection value (this is detected by any suitable means not shown), ! !
11 input to the node 19, and its adjustment output is calculated as the amount of phase change of all ignition pulse phases with respect to the power supply voltage phase. It is said that

Here, as the function generating circuit 17, if the absolute value of the DC average voltage command value E is greater than or equal to a predetermined value A, if E>0, then 1. If E<O, output a value of -1, and if the absolute value of E is less than a predetermined value A, output a function value that decreases from 1 to -1 as E decreases. By adopting a method that Can be controlled smoothly. Further, in this case, since the phase change amount ψ changes continuously, it is possible to control the PWM pattern without disturbing it.

FIG. 2 is a block diagram showing the main parts of another embodiment of the invention. The difference from Fig. 1 is that the output of the M number generating circuit 2° with the DC average voltage command value Ed as input is added by the adder 21 immediately after setting the phase difference between the power supply voltage and the power supply current. The detected value of the phase difference between the voltage and the power supply current is input to the regulator 19, and its output is calculated as the phase change f! of the Q firing pulse phase with respect to the power supply voltage phase. The only difference is that it is an IP.

In this case, when the absolute value of Ed9 is greater than or equal to the predetermined value A, the function generating circuit 2o operates as o if Ed*〉o, and Ed(o
Then, the value of [π-2×(phase difference setting Gi between power supply voltage and power supply current)] is calculated, and the absolute value of Ed* is the predetermined I
When below A, as E♂ decreases, from 0 to [＼ - 2 × (
Exactly the same control as in the case of FIG. 1 can be performed by outputting an increasing function value to the phase difference setting l[)] between the power supply voltage and power supply current.

〔Effect of the invention〕

In this invention, when the DC average voltage command wLEd is equal to or higher than a predetermined value, the phase-advanced current flowing through the low-pass filter is canceled by delaying the phase difference of all ignition pulse phases with respect to the power supply voltage phase by the same amount. control. For this reason, even if Ed is the same cough, the fourth
Compared to the conventional example shown in the figure, the DC average voltage decreases by the amount that the ignition pulse phase is delayed. To obtain current, use the conventional example shown in Figure 4]
However, the embodiments of the present invention shown in FIGS. 1 and 2 require a larger value for Ed.

According to the present invention, under the same main circuit conditions, there is no need to be limited by the minimum pulse width of the self-extinguishing element up to a small DC current range (compared to the conventional example). Note that as the ignition pulse phase is delayed compared to the conventional example shown in Fig. 4, the maximum value of the DC average voltage also decreases, but near the maximum DC average voltage, the phase advance that flows through the low-pass filter included in the power supply current decreases. Since the proportion of current becomes very small, the decrease in the maximum value of DC average voltage is insignificant.

9. In the conventional example shown in Fig. 4, the fundamental wave power factor deviates from the desired output due to not only the influence of the low-pass filter but also the switching delay of the self-extinguishing element, but in the present invention, Since the control works to compensate for the deviation, there is also the advantage that no deviation occurs.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams showing the main parts of an embodiment of the present invention, Figure 3 is a circuit diagram showing an example of the circuit configuration of a three-phase flow rectifier, and Figure 4 is a conventional PWM control. A block diagram showing the ignition pulse generation circuit of a current source rectifier that performs
FIG. 5 is a time chart showing an example of a PWM pattern of a three-phase flow rectifier, and FIG. 6 is a circuit diagram showing a U-phase equivalent circuit of the circuit shown in FIG. Symbol explanation 1...Three-phase AC power supply, 2.°-...Low pass filter, 2a...Filter reactor, 2b
... Filter capacitor, 3 ... Self-extinguishing element, 4 ... DC reactor, 5 ...
...Load, 6... Positive arc wave pattern generation circuit, 7
...Short circuit pulse generation circuit, ...Synthesis circuit, 9 ...Phase shift amount determination circuit, 10...
Short circuit pulse width command value generation circuit, 11... U phase power supply, 12... Reactor, 13... Resistor, 14... U phase filter capacitor, 15・
....multiple flow sources, 17..function generation circuit, 18..multiplier, 19..regulator,
20...Function generation circuit, 21...Adder, S...PWM pattern generation circuit Representative Patent attorney Akio Namiki Patent attorney Seimei Matsuzaki 1 ■ Tomi 2 Figures 3 Figures 6 Figures 4 Figures 5

Claims (1)

[Claims] 1) An output voltage control device for a current source converter, which connects a power source to a current source converter via a high frequency removal filter and controls the output voltage of the converter, comprising: a PWM control means for controlling the ignition pulse width of a bridge-connected self-extinguishing element; and a PWM control means that receives the detected value of the fundamental wave power factor of the power supply and its setting value and adjusts the ignition pulse width so that the two match. a phase control means for controlling the ignition phase of the converter, and when the command value of the output voltage of the converter is Ed^T, |E_d^*|>A (where A is a certain positive constant value) holds true. When the command value E_d^T is within the range, the PW
The M control means controls the ignition pulse width of the self-extinguishing element according to the magnitude of the command value E_d^T, and the phase control means controls the ignition pulse width of the self-extinguishing element in accordance with the magnitude of the command value E_d. , the ignition phase of the ignition pulse is controlled so that the detected value of the fundamental wave power factor of the power source matches its set value, and the command value E_d^* is set within the range where |E_d^*|<A holds true.
When the command value E_
Regardless of the magnitude of d^T, the ignition pulse width of the self-extinguishing element is controlled to a certain constant width, and the phase control means inputs the command value E_d^* according to the magnitude thereof. 1. An output voltage control device for a current source converter, comprising: a control circuit that varies the set value of a fundamental wave power factor itself;