JPS63223910A - Control system for dc power source system - Google Patents

Abstract

PURPOSE:To supply plenty of power to a load, while cooperating with the use rate of a converter use element, by bringing a converter to a constant DC voltage operation, when a load of a current system is less than the maximum power which can be supplied from the system, and executing an AC current control whose setting is varied by a frequency of a power source, when said load exceeds the maximum power. CONSTITUTION:A desired value of the maximum AC current which can be fetched from a power source by a power-factor '1' against a power source use frequency (f) is generated as a function of the frequency (f) from an AC current pattern generator 2, and from an automatic voltage regulator 1, an AC current desired value is generated so that a DC voltage becomes equal to its desired value. When a load exceeds the power which can be supplied, a battery 13 is discharged, the DC voltage drops, an output of the regulator 1 becomes large and exceeds an output of the generator 2, and based on its result, a signal selecting circuit 3 selects an output of the generator 2, and the discharge quantity of the battery 13 is set to the minimum value. In the case of the contrary, the battery 13 is charged, and also, the power corresponding to the load is supplied, and it is suppressed that an excessive arc-extinguishing capacity is requested to a switching element of a converter 12.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a DC power supply system that converts and supplies power from a variable frequency AC power supply using a converter, and particularly relates to a non-contact power supply system for magnetic levitation vehicles. The present invention relates to a control method suitable for a system in which the power frequency fluctuates over a wide range, such as a system in which the power supply frequency fluctuates over a wide range.

[Conventional technology]

In order to efficiently extract DC power from a variable frequency AC power source, conventional devices have developed the relationship between the firing angle α and extinguishing angle β of a converter using GTO, as described in Japanese Patent Application Laid-Open No. 121773/1983. is set within a predetermined range based on a certain relational expression determined by the inductance of the AC power source and the frequency.

However, in this method, the current flows only during a short period of π-(α+β) within the half cycle π of the input power supply, so the peak value of the current becomes a large value, and the G
TO has a large arc-extinguishing current.

[Problems to be solved by the invention] The above conventional technology requires a large arc extinguishing ability for the GTO, which leads to an increase in the number of parallel elements and an increase in the size of the device, and also increases commutation loss, resulting in poor power conversion efficiency. It's bad.

In other words, the above-mentioned conventional technology does not take into consideration the limits of the GTO's ability, especially the arc-extinguishing characteristics, and has a problem in practical application.

An object of the present invention is to provide a control method for a DC power supply system that can reduce the requirements for the arc extinguishing characteristics required for the GTO of the converter and supply power while maintaining sufficient conversion efficiency.

[Means for solving problems]

The above object is achieved by controlling the converter to switch to either a DC constant voltage or an AC current characteristic in which the set value is a function of the power supply frequency, depending on the operating state.

[For production]

If the load on this current system is less than the maximum power that can be supplied by this power system, the converter will operate at constant voltage; if the load exceeds the maximum power that can be supplied by this power system, it will be set to the frequency of the power supply. Since the alternating current characteristic changes in value, it is possible to supply as much power as possible to the load while coordinating with the utilization of the elements used in the converter.

Furthermore, since it is ideal for the power factor of the power source to be as close to 1 as possible, it is common to add a power factor wi control system to the converter. However, at this time, if the power supply frequency and converted power of the converter are increased while the power factor remains 1, the modulation factor of the converter may increase and exceed the allowable value of the converter element.

Therefore, if a modulation factor limiter is provided at this time to worsen the power factor, it becomes possible to exchange power over a wider range.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the control method of the DC power supply system according to the present invention will be explained in detail using illustrated embodiments.

Fig. 2 shows the main circuit of a DC power supply system to which an embodiment of the present invention is applied. , represents the armature (collection coil) of a synchronous generator that generates power as the vehicle travels, and the AC power of variable frequency (determined by the speed of the vehicle) obtained from this armature G is transferred to the voltage source converter 12. It converts to DC, outputs a specified voltage, and charges the battery 3 to create a DC power source.The armature G of the synchronous generator has an internal induced voltage of 9 (E,), an internal inductance of 10 (L,), It consists of an internal resistor 11 (R1), and its AC output is converted into a DC voltage E4 by an automatic converter 12.

Now, if the converter 2 is operated at an input power factor of 1, then the DC output power P, is Pa=3((2"
La"&"(6J"Lm"+Rs")Ec") R
on a(ω"L"-R,")E, ((ωzL,"+RasEc'-ω"Lm2Ea")")/((1)"L"+R
11")"-"=・(1) (ω: power source angular frequency)

Note that k represents the modulation rate in 0≦ and ≦2.

π Also, the limit converted power that can be extracted to the DC side with respect to the AC output voltage E at this time is as follows: (i) The limit converted power in the case is Pdl, and the limit converted power in the case (ii) is P4□. Then 4R.

・・・・・・・・・(4) becomes.

On the other hand, in addition to the limits based on these equations (3) and (4),
Switching element (G
There is also a limit area due to the arc extinguishing allowable current of TO, etc.).

Therefore, when the above is summarized, the operating characteristics of this system are as shown in Fig. 3.

This figure 3 shows the output frequency f of the synchronous generator on the horizontal axis and the converted power P on the vertical axis, and shows three types of characteristics ■, ■
, ■ are shown.

Characteristic ■ is the maximum convertible power limited by the resistance 11 of the synchronous generator coil, and is obtained from equation (3).

Characteristic ■ is the maximum convertible power limited by the allowable current of the switching element used in the converter.

Characteristic (2) is the maximum power that can be converted at a power factor l determined by the DC voltage and the maximum allowable modulation factor of the converter.

Next, the characteristics shown by the thick solid line in FIG. 3 show an example of the operating characteristics according to an embodiment of the present invention, and the following control is performed.

In section I, that is, from frequency O to the frequency where ■ and ■ touch, the converter input current is proportional to the operating frequency, and is raised from 0 to Im*ax (the maximum allowable alternating current determined by the elements used in the converter).

Next, in section (2), constant alternating current control is performed at Ias+mx.

Section 1. In II, control is performed at a power factor of 1, but in section ■, delayed power factor control is performed and operation is performed at the maximum allowable modulation factor. In 〇 and above, the load power always exceeds the power that can be supplied by the converter. In this case, the converter operates in the current control region throughout the entire section, and the convertible power shown in (1) and (2) can be effectively converted.

On the other hand, the characteristic shown by the large broken line in FIG. 3 is another example of the operating characteristic according to an embodiment of the present invention, in which the load power becomes lower than the convertible power of the converter 12 at a certain frequency f; It is.

First, section ■9 section ■' is similar to thick solid line characteristics I and ■, respectively.

Thus, in the section ■'', the converter 12 is controlled with a power factor of 1 in the constant voltage control region, but in the section ■', the power factor becomes a lagging power factor in the constant voltage control region.

In this way, according to the embodiment of the present invention, a DC power supply system with a high utilization rate of convertible power can be easily obtained.

FIG. 1 shows an embodiment of a control circuit for controlling the main circuit described above. In FIG. 1, ■ is a difference signal εE4 between the DC voltage target value E+Ip and the feedback value E4
AVR (automatic voltage regulator) creates AC current target value ■3, 1 from AC current target value I□ from power supply frequency f.
3 is a signal selection circuit that outputs the smaller signal of the target (direction I1.. and I□) as the AC current target value 1 st; 4 is an ACR (automatic current regulator) that generates the converter AC input terminal voltage imaginary component IMIEc,l from the error signal of the AC current target value I0 and the feedback value 1 from ε11.On the other hand, 5 is the AC input voltage E1 and A phase detector that determines the J AC input phase angle φ from the AC input current ■3,
6 is the error signal ε between the AC input phase angle φ and its target value φ
From φ to converter AC input end voltage real number component R, l Ec
7 is the APR (automatic phase adjuster) that creates 1. I
From Ec l and RclEc l, argEc and lEc
A coordinate converter that creates l, 8 is the angular component of polar coordinates arg
This is a pulse generator that creates a gate pulse to be applied to the switching element of the converter 12 from Ec and a modulation rate created by dividing the length component IEcl by E4. Note that the APR 6 includes a limiter that limits the magnitude of its output Rcl Ecl so that the value of k does not exceed a predetermined tolerance value.

Next, the operation will be explained.

First, the alternating current slam generator 2 generates a target value of the maximum alternating current that can be extracted from the power supply at a power factor l with respect to the power supply frequency f as a function of f. However, the output is limited by a limiter so that it does not exceed the maximum allowable alternating current determined by the switching elements used in the converter 12.

On the other hand, AVRl generates an AC current target value such that the DC voltage is equal to its target value.

Now, if the load on this power supply system exceeds the power that can be supplied by this power supply system, the battery 13 will discharge and the DC voltage Ed will decrease, so the output of the AVR 1 will increase, and the output of the AC bang generator 2 will increase. It will exceed the output. As a result, the output of the AC current slam generator 2 is selected by the signal selection circuit 3 as the AC current target value I Since the maximum electric power is used for moxibustion, the discharge amount of the battery 13 can be set to the minimum value.

Conversely, if the load of this power supply system is lower than the power that can be supplied by this power supply system, the battery 13 will be charged and the DC voltage E4 will rise, so the output of AVRl will become smaller and the output of the AC bang generator 2 will be reduced. It starts to go down.

As a result, the signal selection circuit 3 selects the AC current target value 1.
Since the output of AVRl is selected as st, the power supply system enters the first control mode, and when the battery 13 is charged, both supply power commensurate with the load.

Therefore, according to this embodiment, the switching element of the converter 12 is not required to have excessive arc extinguishing ability, and even if the output frequency of the synchronous generator changes greatly, sufficient conversion efficiency can be maintained at all times. As much power as possible can be supplied to the load.

〔Effect of the invention〕

According to the present invention, in a DC power supply system that inputs a variable frequency AC power supply, maximum output can be obtained from a low frequency close to O to the highest frequency, and,
The extinction current of the GTO is also small (the number of GTO users can be greatly reduced), and since the erasing current is small, the switching loss is also small (the gate device can also be made smaller).

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a control method for a DC power supply system according to the present invention, and FIG. 2 is a block diagram showing an example of a DC power supply system to which an embodiment of the present invention is applied.
FIG. 3 is a characteristic diagram illustrating the present invention in detail. 1...AVR (automatic voltage regulator), 2.
・・・・・・・・・AC current slam generator, 3・・・・・・
・・・・Signal selection circuit, 4・・・・・・・・・ACR(
automatic current regulator), 5... phase detector,
6...APR (automatic phase adjuster), 7.
・・・・・・・・・Coordinate conversion circuit, 8・・・・・・・・・
Pulse generator, 9... Generator internal induced voltage, 10... Generator internal inductance, 11... Generator internal resistance, 12
...... Voltage type self-excited converter, 13...
······Battery. Figure 2 Figure 3 ft f Procedural correction band (voluntary) β/27, 1988

Claims (1)

[Claims] 1. A voltage-type power converter for converting alternating current power into direct current power, and a battery connected in parallel to the direct current output of this converter, so as to obtain direct current power from a variable frequency alternating current power source. In the DC power supply system, a control means is provided for switching the control state of the voltage-type power converter between a first mode and a second mode, and when the voltage of the battery is maintained at a predetermined value or higher, the voltage-type power converter is operated. The device is configured to perform constant voltage control, and when the voltage of the battery is less than a predetermined value, the voltage type power converter is controlled so as to exhibit an alternating current characteristic in which a set value is a function of an alternating current power frequency. A control method for a DC power supply system that is characterized by: 2. In claim 1, the control means:
an automatic voltage regulator that obtains a first AC current target value by comparing the voltage of the battery and a DC target voltage;
an alternating current pattern generator that obtains a second alternating current target value that takes a constant value when a certain value is exceeded; and a signal selection that selects the smaller of the first and second alternating current target values. a circuit, an automatic phase adjuster that compares the output power factor of the AC power source with the power factor target value, and an AC input current of the voltage type power converter that takes in the output signals of these signal selection circuits and the automatic phase adjuster; A DC power supply system comprising a pulse generator that supplies gate pulses to the voltage type power converter so that the AC current target value and the power factor converge to the AC current target value and the power factor target value, respectively. control method. 3. The control method for a DC power supply system according to claim 2, wherein the pulse generator is configured to have a limiter function that limits the modulation rate by the gate pulse.