JPS60207455A - Power converter - Google Patents

Abstract

PURPOSE:To obtain a high performance power converter by compensating the variation in a transmission gain by a signal compared of the state variation in a control system with the state variation in a simulation control system. CONSTITUTION:A power converter 1 has a thyristor converter 3 and a smoothing circuit 4, and supplies power to a load 2. The converter 3 is controlled at alpha by a phase controller 7 of a main current control system 13 to form a phase control signal 11 from a current deviation signal between a current feedback signal from a current detector 8 and a current command value 9. In this case, a simulation current control system 18 is composed of a simulation smoothing circuit 14 similar to the smoothing circuit 4 and a unit 17 simulating the controller 7. Thus, the second phase control signal 12 obtained through a compensating amplifier 21 from the system 18 is added to the signal 11 to obtain an input signal of the controller 7. In this manner, the transmission gain decrease of the system 13 is compensated to eliminate the large variation in the current control response.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a power conversion device using a thyristor converter, a reactor and a capacitor f'l having saturation characteristics in a smoothing circuit, and the present invention relates to a thyristor converter which is generated by intermittent current. This is a power conversion device (2) that aims to improve the current response of a current control system by compensating for the nonlinear characteristics of the reactor caused by the magnitude of the flowing current and the nonlinear characteristics of the output voltage.

[Technical background and problems of the invention]

The output voltage (average voltage) Ed of the thyristor converter is generally (
It is shown by equation 2(1).

Ed = K(2)α・Song・(1) However, K is a constant determined by the input voltage, number of rectification phases, etc.
α is the control delay angle.

Therefore, by using the inverse cosine ISI number, the phase control signal s
If p, 4 is given, the relationship with the control delay angle α becomes (Equation 21), where the output voltage Ed of the thyristor converter and the phase control signal S
As for the pH relationship, a C-biproportional relationship holds true as shown by equation (3).

crs a = SpH--・421 Ed = K・SpH (3) If a phase control device with inverse cosine function characteristics is combined with a thyristor converter, it can be considered as a proportional amplifier. .

However, the above equation (1) holds true under the condition that the current flowing through the thyristor converter is continuous, but does not hold true under the condition that the current flows intermittently.

That is, the instantaneous value of the thyristor converter output voltage during the current intermittent period is determined by the current intermittent state, and the output voltage Ed has a nonlinear characteristic different from the equation (3).

From the above, if we combine the thyristor converter and the phase control device and compare them with the elements in the control system, the control system will contain C2 nonlinear elements, and this nonlinear characteristic will appear in the intermittent state of current. come.

In addition, in a power conversion device equipped with a smoothing circuit using a reactor and a capacitor at the output of the thyristor converter, the current intermittent of the thyristor converter may be is likely to occur and becomes complicated. In addition, the general smoothing circuit (for dual-current smoothing and to prevent current interruption as much as possible) is small and lightweight by giving it C bisaturation characteristics so that it has a small inductance at large currents and a large inductance at small currents. This is due to the complexity of the intermittent current state, and the nonlinear characteristics of the accelerator directly make the control system nonlinear, making the current control of the power conversion device a more complicated nonlinear control system.

In the current control system of a normal power replacement device, if the current control response is adjusted when the current is not intermittent, the current control response when the current is intermittent becomes extremely slow, and even when the load current is large or small. It had the disadvantage that the current control response was different.

This drawback is due to the fact that the current control system includes nonlinear characteristics due to intermittent current and nonlinear characteristics due to saturation characteristics of the reactor, and the open loop transfer gain of the current control system changes. Based on this recognition, conventional devices have proposed a method to improve the above-mentioned drawbacks by providing a voltage control system in the minor loop of the current control system to increase the open loop transfer gain of the entire current control system, and by detecting current intermittent conditions. Methods have been used in which compensation is achieved by switching multi-stage gain controls within the current control system. However, the change in open loop transfer gain due to nonlinear characteristics is affected by the smoothing circuit's saturation characteristics, capacitance and charging/discharging conditions, the magnitude of the load current, and the characteristic C2 of the ζ thyristor element. , the open-loop transfer gain in the discontinuous state is extremely complex, and with the conventional compensation method described above, it is difficult to perform satisfactory compensation, and only a slight improvement in characteristics can be obtained. There was a shaft.

[Purpose of the invention]

The object of the present invention has been made in view of the above-mentioned conventional problems, and is to provide current control in which the current control response does not change significantly depending on the current continuous state and current intermittent state in a thyristor converter, and the magnitude of load current. The purpose of the present invention is to provide a power conversion device with a power conversion system.

[Summary of the invention]

In order to achieve the above object, the present invention provides a phase control device which includes a smoothing circuit consisting of a thyristor converter, an accelerator, and a capacitor, supplies electric current to a load, and controls the firing timing of the thyristor of the thyristor converter. and a current detector that detects the current flowing through the thyristor converter C2, and a main current control loudspeaker that amplifies a deviation signal obtained by subtracting the output signal of the current detector from the current command value. , in a power conversion device in which a current control system is configured such that the main current control amplifier output signal becomes a first phase control signal of the phase control device, detecting a load current that is an output of the smoothing circuit; A load current detector determined by calculation, a simulated current control system that simulates the main current control system including the thyristor converter, and the smoothing circuit, and the output voltage C of the power conversion device.2 A voltage for obtaining a corresponding output voltage signal. The simulated current control system includes a detection circuit and a compensation amplifier that amplifies the deviation signal obtained by subtracting the output voltage signal r detected by the voltage detection circuit from the output simulated filling signal obtained from the simulated current control system. System DC output simulation terminal ζ
Y, the load current detector is connected to provide a simulated load current signal of the simulated current control system 'iJ>, the output signal 7al of the compensation amplifier - the second digit 4'd control signal, and the first By adding the phase control signal and the phase control signal Δ of %2 and using it as the input signal of the phase control device, the current control response is determined by the current continuous state and current intermittent state in the thyristor converter and the magnitude of the load current C2. The key feature of this method is that it does not change significantly.

[Embodiments of the invention]

Hereinafter, an embodiment in which the power converter according to the present invention is applied to a current source device that supplies a commanded current to a load such as a current control device for plating will be described with reference to FIG.

The power converter l that supplies the load 2 (two-power) is equipped with a thyristor converter 3 and a smoothing circuit 4, and the smoothing circuit 4 has a saturation characteristic and is composed of an accelerator 5 and a capacitor f6. The current flowing through the thyristor converter 3C is α-controlled by the phase control device i17, and is detected by the current detector 8. This current detection signal becomes a current feedback signal, and the difference between it and the current command value 9 is taken, and it becomes a current deviation signal. This current deviation signal is the main current control amplifier 1.
The first phase control signal 11 obtained by being amplified by 0
The main current control system 13 is configured such that a second phase control signal 12 (described later) is added to the input signal T and becomes an input signal to the phase control device 7.

Next, a phase control device 7 and a proportional amplifier 15 simulating the thyristor converter 3 are connected to a simulated smoothing circuit 14 having the same configuration as the smoothing circuit 4. The current equivalent signal detected by the simulated current detector 16 becomes a current feedback signal, and the difference is taken from the current command value 9. The signal obtained by amplifying it by the simulated current amplifier 17 becomes the input to the proportional amplifier 15 and performs simulated current control. The simulated load current of the simulated current control system 18 is connected to the load current detector 19I: therefore, the simulated smoothing circuit 14 to simulate the load 2. Also, the output voltage of the main current control system J3 The difference between the output voltage signal that is the output from the voltage detector 20 that detects a signal corresponding to The obtained signal is added as a second phase control signal to the first phase control signal, which is the output signal of the main current control amplifier 10, and becomes an input to the phase control device 7.

Here, the proportional amplifier 15 and the simulated reactor 22 of the simulated smoothing circuit 14 are linear, and C
′- selected. The output of the load current detector 19 is a current source signal corresponding to the load current, and is a simulated capacitor of the simulated smoothing circuit 14. 23 is connected in parallel.

Comparing the main current control system 13 and the simulated current control system 18 configured as described above, it can be seen that the respective components correspond to each other. Therefore, the main current amplifier 10 and the simulated current amplifier 17 have the same characteristics, and the main current control system 1
If the open loop transfer gain of No. 3 and the open loop transfer gain of the simulated current control system 18 are the same, the characteristics of both current control systems will be the same. Changes in current command 9 (2) The movement of the accompanying state variables in the transient state and the movement of the state variables in the transient state accompanying changes in the load current are the same under all conditions.C2 is the main current It is necessary that all the elements in the control system 13 have linear characteristics, because all the components in the simulated current control system 18 have linear characteristics.

In other words, it is clear that the difference between the state variables in the transient state is caused by the nonlinear characteristics of the components in the main current control system 13. Therefore, the second phase control signal 12, which is the difference between the two state variables, is a signal that occurs due to the current intermittent phenomenon caused by the thyristor converter 31 and the saturation characteristics of the accelerator 5.The main current control system 13 and the simulated current When the element characteristics of the control system 18 are the same, the second phase control signal 12 is zero, and the simulated current control system 18 does not give any flux to the main current control system 13i.Next C2, the load current becomes smaller. Considering the situation, if the accelerator 5 has a saturation characteristic and has a large inductance value, and if the current of the thyristor converter 3 is intermittent, then the open loop transfer gain of the main current control system 13 will be extremely reduced. The open loop transfer gain of the simulated current control system 18 is not liquefied. Therefore, although the current response of the main current control system 13 is delayed due to load reaction and changes in the current command 9 (-), the current response of the simulated current control system 18 is Since I is not delayed, the difference appears as the second phase control signal 12. Therefore, this second
phase control signal 12'? By adding it to the first phase control signal 11, the reduction in the transfer gain of the main current control system 13 is compensated for by immediately forcing the output voltage of the SiRisk converter 3 to decrease.

Due to the above-mentioned effects, it is possible to prevent the current control response from being greatly liquefied due to the intermittent current of the SIRISK converter 3 or the magnitude of the load current.

In Example C, the components of the simulated smoothing circuit 14 are expressed as a reactor and a condenser, but any element other than the reactor or condenser may be used as long as the characteristics can be simulated.

FIG. 2 is a block diagram showing another embodiment of the power converter according to the present invention. The current #i configured in the figure is the same as the device, so the explanation will be omitted, but the load 2a is DC to AC double force conversion T
In the case of an inverter device, etc., the output voltage of the power converter l is set to a predetermined voltage (2).
4 is provided to constitute a voltage control system. Therefore, the main current control system 13 in the power converter l is configured to be a mica loop of a voltage control system. In such an application example, the load 2a is unrelated to the voltage control system or the power converter l (two-load current flow), or the voltage command of the voltage control system may be determined by the operation method of the load 2a. It can be said that the state inside the power converter is determined by the load 2a. This means that the output voltage of the power converter l is influenced by the load 2a, but the power The characteristics of the main current control system 13 in the converter l have been improved and it has the same current response characteristic in all conditions, so the response of the voltage control system, which is in a minor loop, is also It can be made faster and the load (due to the increase in summer movement) can be lowered.

〔Effect of the invention〕

According to the power conversion device of the present invention, the
Nonlinear characteristics depending on control conditions such as whether the passing current is continuous or intermittent? Control elements (phase controllers and silicate converters) that have non-linear characteristics whose constants change depending on the magnitude of the load current (saturation characteristics and torque handles) Compensate for changes in transfer gain caused by nonlinear characteristics by compensating with a signal obtained by comparing the state variables in the control system and the state variables in a simulated control system that simulates the control system using linear elements. As a result, the current control response of the power converter greatly liquefies and the current control response of the power converter becomes 7L.
It is possible to provide a power conversion device with two types. Therefore, it is a high-performance power converter even at low currents without special compensation, and furthermore, if the power converter according to the present invention is applied in a configuration such as a minor loop system. This is a power conversion device that can also improve the characteristics of its major loop system.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the power conversion device according to the present invention applied to current control such as plating, and Fig. 2 is a DC voltage supply device g dual use of an inverter device that converts DC to AC C″-power. It is a configuration diagram showing another embodiment of the present invention.■...Power conversion device 2...Load 3...Sirisk converter 4...Hei?11 circuit 5.
・・Reactor 6・・Contents 7・・Phase control device 8・・Current detector 9・・Current command value 10・
...Current control amplifier 11...First phase control signal"2...Second phase control signal 13...Main current control system 14...Simulation smoothing circuit 15
... Proportional amplifier 16 ... Simulated current detector 17 ...
- Simulated current control amplifier 18... Simulated current control system 19... Load current detector 20... Voltage detector 21... Compensation amplifier 22...
・Simulated reactor O...Simulated capacitor 24...
Voltage Control Amplifier Kuha (7317) Agent Patent Attorney Noriyuki Chika (and 1 others)
given name)

Claims (1)

[Claims] The thyristor converter is equipped with a smoothing circuit consisting of an accelerator and a capacitor to supply power to the load, and a phase control device for controlling the firing timing of the thyristor converter and detecting the current flowing through the thyristor converter 5. The main current control amplifier includes a current detector and a main current control amplifier that amplifies a deviation signal obtained by subtracting the current detector output signal from the current command value, and the main current control amplifier output signal is controlled by the phase control device. In a power conversion device-2 in which a current control system is configured to provide a first phase control signal, a load current detector which detects a load current sound which is the output of the smoothing circuit or is detected by calculation, and a load current detector which is detected by a calculation, A simulated current control system that simulates the main current control system including a converter and a smoothing circuit, and an output voltage signal corresponding to the output voltage C2 of the power converter? and a compensation amplifier that amplifies a deviation signal obtained by subtracting the output voltage signal detected by the voltage detection circuit from the output simulated voltage signal obtained from the simulated current control system, The load current detector is connected to a DC output simulation terminal of the current control system to provide a simulated load current signal from the simulated current control system, the output signal of the compensation amplifier is used as a second phase control signal, and the output signal of the compensation amplifier is used as a second phase control signal. A power conversion device characterized in that the phase control signal and the second phase control signal are added and used as an input signal of the phase control device.