JPS6377379A - Constant voltage controller for converter - Google Patents

Abstract

PURPOSE:To control constant voltage with response at high speed when load suddenly fluctuates by comparing a voltage reference signal and a voltage feedback signal proportional to the output voltage of a converter and controlling the ignition phase of the converter by using the deviation signal of both signals. CONSTITUTION:A voltage transformer 101 detects the AC voltage of a converter 7, and the AC voltage of the converter 7 is converted into unit display voltage epu by a voltage-voltage converter 103. A current transformer 102 detects the currents of the converter 7, the currents of the converter 7 are converted into a voltage signal by a current-voltage converter 104, and unit display currents ipu are outputted. An output x/2.ipu/epu is outputted to an adding point 108 by employing a dividing circuit 105 and a regulation coefficient 106. On the other hand, Ed/1.35EAC (Ed: DC voltage and EAC: AC voltage of converter) acquired from a dividing circuit 111 is inputted to the adding point 108. An output from the adding point 108 functions as a command value as the constant voltage of open-loop control.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention relates to a constant voltage control device for a converter using a controllable electric valve such as a thyristor, and particularly relates to a constant voltage control device for a converter that uses a controllable electric valve such as a thyristor. ,
The present invention relates to a constant voltage control device for a converter that exhibits a stable response during steady state.

(Prior Art) Fig. 4 shows a basic block diagram of a conventional negative feedback type constant voltage control device used in a converter that supplies DC voltage to electric train loads, DC motors, etc. FIG. 5 is a characteristic graph of the conventional constant voltage control device. Conventional constant voltage control will be explained below using these.

1 is a voltage reference setter, 2 is a summing point, 3 is an error amplifier circuit,
4 is an ignition pulse phase shift circuit, 5 is an insulation amplifier, 6 is a converter transformer, 7 is a converter, and 8 is a DC voltage detection circuit. The output voltage of the converter 7 is detected by a DC voltage detection circuit 8 and converted to a voltage level that can be easily handled by a control circuit. This voltage signal is referred to as Ef (hereinafter referred to as voltage feedback signal). Furthermore, this signal is separated between the output of the converter 7 and the control circuit by the isolation amplifier 5. The polarity of the output signal of the isolation amplifier 5 is inverted and inputted to the turning point 2. The voltage reference signal El-6f given by the voltage reference setter 1 is the target output voltage value of the converter 7. The output of addition point 2 is the voltage feedback signal Ef and the voltage reference signal E? Deviation of ef (Er.t
Er). This deviation is amplified by an error amplification circuit 3 with a certain fixed gain, and is further amplified by an ignition pulse phase shift circuit 4.
The ignition pulse that is input to the ignition pulse generator and subjected to 9-phase control is obtained as the output of the ignition pulse phase shift circuit 4. This output pulse fires the controllable electric valve of the converter 7 and controls the output voltage of the converter.

The output voltage of the converter is input to a DC voltage detection circuit 8.

Therefore, the constant voltage control system becomes a closed loop.

It always operates so that the difference between the voltage reference signal EP31 and the voltage feedback signal Ef is minimized. When the output voltage of the converter 7 exceeds the voltage corresponding to the voltage reference signal, the deviation signal Epet
Ef increases and acts to throttle the voltage.

Conversely, when the output voltage of the converter 7 becomes less than the voltage corresponding to the voltage reference signal, the deviation signal EPf3f-Ef increases, working in the direction of increasing the voltage.

(Problem to be solved by the invention) However, in reality, the error amplification circuit 3 for constant voltage control is a circuit that delays the response in order to ensure stable operation of the control system, and it takes time for constant voltage control to work. It takes. Therefore, the converter 7 cannot sufficiently respond to sudden voltage changes due to instantaneous fluctuations in loads that are close to load short circuits, and in some cases there have been problems such as the inability to rapidly accelerate the train. The operation will be explained using FIG. The horizontal axis is the DC output current.

The vertical axis is the DC output voltage, and when the DC output current is zero or close to zero, the output voltage is similar to the voltage reference signal EPef. When the load slowly draws a direct current, the characteristic is that it rides on a horizontal curve as shown by D in FIG. However, if the load suddenly draws a direct current, the error amplification circuit 3 operates with a delay, so the changes occur in the order of A → B → C in Figure 5.
Since the error amplification circuit 3 does not operate at all in the operation from A to B, the characteristic lies on the regulation curve determined by the reactance of the converter transformer 6 and the system load actance. Therefore, this device is a constant voltage control device, but the worst case is B
The output voltage of the converter 7 decreases up to a point.

The object of the present invention is to eliminate the drawbacks of the prior art and to provide a constant voltage control device for a converter that responds quickly even during transients.

[Structure of the invention]

(Means for solving problems) The present invention is a conventional closed loop constant voltage control circuit.

It consists of an open-loop constant voltage control circuit using equation 0, which is a mathematical equation representing the characteristics of the converter.

where Ed: DC voltage EA (:: AC voltage of converter ) formula is the converter's AC voltage EAC*bar unit reactance X for the required DC voltage Ed.

The phase control delay angle α is calculated using the unit display voltage ePU of the converter and the unit display current ipu of the converter.

(Function) The present invention enables constant voltage control with high-speed response when the load suddenly changes due to the aforementioned open-loop constant voltage control circuit.

(Example) The invention will be explained in more detail below by means of examples.

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

Elements with the same symbols as in FIG. 4 are elements having the same functions.

In FIG. 1, 101 is a voltage transformer, 102 is a current transformer,
103 is a voltage-voltage converter, 104 is a current-voltage converter, 105 is a division circuit, 106 is a coefficient indicating regulation, 107 is an open loop control reference, 108 is a summing point, 1
09 is a phase advance priority circuit, 110 is a voltage-to-voltage converter, and 111 is a division circuit.

The conventional closed loop constant voltage control circuit has been described previously and will therefore be omitted. An open loop constant voltage control circuit will be explained using FIGS. 1 and 2.

In FIG. 1, the voltage transformer 101 is for detecting the AC voltage of the converter 7, and the main circuit is MR and the voltage -
A voltage converter 103 converts it into a unit display voltage ePtl with a rated voltage of 1.0. The current transformer 102 is for detecting the current of the converter 7 and is insulated from the main circuit.The current-voltage converter 104 converts the current signal into a voltage signal, and the rated current of the converter 7 Convert to unit display current ipu with 1.0. Next, a division circuit 105 divides the output ePu of the voltage-voltage converter 103 as the denominator and the output ipu of the current-voltage converter 104 as the numerator.The output of the division circuit 105 by 6 is inputted to the regulation coefficient 106. Multiply. Enter the calculation point 108.

It will be realized by the method described. A signal from the voltage transformer 101 is input to a voltage-to-voltage converter 110, where it is converted into an electronic circuit level signal. Naturally, this signal is proportional to the voltage of the main circuit, is converted to a standardized value based on the rated voltage, and is treated as the EAC value of the first term on the right side of equation Q). Next, the open loop is determined, and this becomes the target value for open loop control.The zero-order divider circuit 111 inputs the signal from the open loop control base @107 as a numerator, and inputs the signal from the voltage-voltage converter 110. Input it as the denominator, (the 1st addition point 108 on the right side of equation 0 is the regulation coefficient 106
The signal from the divider circuit 111 and the signal from the divider circuit 111 are input. It indicates this addition and becomes a command value for maintaining a constant voltage in open loop control.

Furthermore, the output of the addition point 108 and the output of the error amplification circuit 3 are input to a phase advance priority circuit 109. Phase advance priority circuit 1
09 is a circuit that selects the one that advances the phase control delay angle α with priority among the two inputs. This phase advance priority circuit 1
The signal selected in step 09 is input to the ignition pulse phase shift circuit 4, and the 2-phase controlled ignition pulse is input to the ignition pulse phase shift circuit 4.
It is output as is.

The controllable electric valve of converter 7 is ignited to control the output voltage of converter 7.

Now, the operation of the present invention described above will be explained using a graph in FIG. In this figure, the horizontal axis and thin axis are the same as those described in FIG. However, here, the open loop control standard is set slightly lower than the closed loop control standard. When the DC output current is zero or near zero, the closed-loop voltage reference EP@t
The output voltage is equivalent to . When the load slowly draws a direct current, the characteristic is that it rides on a horizontal curve as shown by D' in FIG. However, when the load suddenly draws a direct current, the closed-loop constant voltage control has a delay, resulting in the characteristics shown in Figure 5, but the open-loop constant voltage control has almost no delay, so it meets the open-loop control standard. value and changes from A' to B' on the characteristic shown by the broken line. B'
The transition from C' to C' means that the closed-loop constant voltage control has started to follow the load change from a delayed state, and at the stage when the closed-loop control has caught up, the closed-loop control side command and the open-loop control side command This is because when compared, the closed loop control side becomes the phase advance side, and is selected and controlled accordingly. The reason why this closed-loop control side is selected is that the open-loop control reference is set lower than the closed-loop control reference, so that the higher the reference value, the more advanced the phase is.

As can be seen by comparing FIGS. 2 and 5, the effect of the embodiment of the present invention is that when the load suddenly changes, the effect of constant voltage can be obtained rather than constant voltage control that does not provide any countermeasures. Further, when the load changes steadily and slowly, phase control is performed using closed loop control with high control accuracy.

Another embodiment of the invention is shown in FIG. The configuration diagram shown here assumes that voltage fluctuations on the AC side of the converter 7 are small. In Figure 1, the AC side voltage is detected by the voltage transformer 101 and converted to the AC voltage EAC of the converter using an electronic circuit. The unit display voltage epu of the device is omitted. In other words, in equation (■), EAC is constant v at the rated voltage.
epu is 1.0. It is assumed that u is constant. However, the open loop control standard 107 is [Effect of the Invention] According to the present invention, 11! A constant voltage control device for a converter that drives a car has the effect of being able to climb a sudden and heavy load, such as when a train climbs a steep hill, without causing a voltage drop and without reducing the speed of the train.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of FIG. 1, FIG. 3 is a diagram showing another embodiment, and FIG.
The figure is a configuration diagram of conventional constant voltage control. FIG. 5 is a diagram for explaining the operation of FIG. 4. 1... Voltage reference setter 2... Addition point 3...
Error amplification circuit 4... Ignition pulse phase shift circuit 5... Isolation amplifier 6.
...Converter transformer 7...Converter 8...DC voltage detection circuit 101...Voltage transformer 102...
Current transformer 103...Voltage-voltage converter 104...Current-voltage converter 105...Divider circuit 106...Ignition coefficient 107...Open loop control reference 10g...Summing point 1
09... Phase advance priority circuit 110... Voltage-voltage conversion Wl! 111...Division circuit Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] The voltage reference signal given from the voltage reference setter is compared with a voltage feedback signal proportional to the output voltage of the converter, and the deviation signal is applied to a constant voltage error amplification circuit, and the above-mentioned a first means for controlling the firing phase of the converter so that the output voltage of the converter has a value corresponding to the voltage reference signal; and an AC voltage E_A of the converter.
＿C, DC voltage Ed, converter unit display current i_P
_U, unit display voltage of the converter e_P_U, bar unit reactance of the converter
_C)+(X/2)+(i_P_U/e_P_U) A constant voltage control device for a converter, comprising second means for determining a phase control delay angle α from the relationship expressed by:_C)+(X/2)+(i_P_U/e_P_U).