JPH0322868A - Power source device - Google Patents

Abstract

PURPOSE:To make a regenerating power converter unnecessary and miniaturize the whole of the title by device by a method wherein a bipole switch is connected to a capacitor for initial charging, which is functioned as a DC filter, and a switch is put ON upon the last transition of the current of an electromagnet to provide an AC/DC power converter with the role of power regeneration. CONSTITUTION:Simultaneously with the starting of the forward operation of an AC/DC power converter 2 at a time t1, a bipole switch 3c is put ON and the initial charging of a capacitor 3b is effected. A starting thyristor switch 5 is put ON by a starting signal at a time t2 and a power is supplied to an electromagnet 4. The electromagnet 4 is controlled so that the same is risen up to the maximum value substantially at a time t3 and the switch 3c is put OFF at a time t4 to transit the converter 2 into reverse converting operation. Thereafter, accumulated energy in the coil of the electromagnet 4 is regenerated at the side of an AC power source 1 and the time is returned to a time t1', corresponding to the time t1, again, then, the same operations are repeated.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a power supply device used for a high-inductance electromagnet in an accelerator such as a synchrotron, and in particular, it minimizes ripples when power is supplied to a triangular or trapezoidal electromagnetic current. The present invention also relates to a power supply device that can shorten one supply cycle.

(Prior Art) Electromagnets in accelerators such as synchrotrons generally have large inductance, and the power supply device shown in Figure 5 is conventionally known as a power supply device used for this. In the figure, 1 is an AC power supply, and this AC power supply 1 includes a Sanwa AC-to-DC power converter (hereinafter referred to as an "AC/DC power converter") 2 configured with a thyristor bridge.
A power supply device consisting of a voltage smoothing glue actor 3a is connected. An electromagnet 4 consisting of a resistance 4a and an inductance 4b is connected to this power supply device.

The operation of the power supply device having the above configuration will be briefly explained.

Cross/1! The power converter 2 continuously converts the AC voltage input from the AC voltage g1 into a positive or negative DC voltage by controlling the firing angle α of the thyristor which is a component thereof, and supplies and regenerates electric power. I can do it. The ideal waveform of the electromagnet current and the waveform of the output voltage of the AC/DC power converter 2 at this time are shown in FIG.

By the way, for example, the electromagnet current required in a synchrotron is a triangular wave or a trapezoidal wave (triangular wave in Fig. 6).
It is. Therefore, the voltage ■. applied to both ends (P-N) of the electromagnet 4. is expressed as dt when the electromagnet current starts up. However, i. is the electromagnet current, Lm indicates the value of the inductance component 4b, and the value of the Rsit resistance component 4a. In this case, V is a positive polarity (based on N in Fig. 5), and the AC/DC power converter 2 performs a forward conversion operation so that the firing angle α of the thyristor is 90'' or less. It is driven by.

On the other hand, when the electromagnet current falls, the voltage V is expressed as dt. In this case, V1 has a reverse polarity and the AC/DC power converter 2 performs a reverse conversion operation, so that it is operated so as to delay the control angle α of the thyristor by 90° or more.

In this way, the AC/DC power converter 2 can supply electric power to the electromagnet 4 using a triangular wave current or regenerate electric power by controlling the firing angle α of the thyristor.

Note that the reactor 3a is provided to smooth voltage ripples that occur when controlling the firing angle of the thyristor, and to supply a current with less ripple to the electromagnet 4.

(Problem to be solved by the invention) However, the conventional power supply device described above has the following problems.

(1) In the power supply unit 1rt of a synchrotron or the like, it is necessary to perform highly accurate control over the set value of the electromagnet current when starting up the electromagnet current and during flat top operation. For example, when starting up the electromagnet current, accuracy of the order of ±10-3 is required for the electromagnet current set value within a range of several percent to lOO% of its maximum value. If this accuracy decreases, problems will occur, such as making it impossible to inject charged particles into the synchrotron. In general, factors that determine the accuracy of the electromagnet current of an accelerator are the output ripple voltage of the AC/DC power converter that constitutes the power supply device and the tracking of the current reference iref (not shown) of the control circuit of the AC/DC power converter. The reason for this is gender. Of these, the output ripple voltage will be explained below. For example, in FIG. 5, a voltage ripple ΔV corresponding to the firing angle α appears superimposed on the DC voltage V on the output side of the power supply device (on the electromagnet 4 side of the reactor 3a). Now, the value of the inductance 4b of the electromagnet 4 is L+-,
The value of the resistance component 4a is Rl1, and the ripple frequency is fr
Then, in general, 2 x f r-Lm> R-. Therefore, the above voltage ripple Δ
The ripple ΔiIII of the electromagnet current generated by V is Δ i l11'F Δv/(2 π fr− L−)
It is expressed as

As can be seen from the above equation, by decreasing the value of ΔV applied to the electromagnet 4 and increasing the ripple frequency fr, it is possible to reduce the ripple current and obtain a highly accurate electromagnet current. Obtainable.

Therefore, it has been considered to increase the ripple frequency fr by increasing the number of phases of a two-power converter, thereby reducing the ripple current Δi generated in the electromagnet current to some extent. However, even if such measures are taken, Δi
It is not possible to make the − value negligible for accuracy reasons. Therefore, in order to further reduce the ripple current Δia so that it can be ignored in terms of current accuracy, it is necessary to provide a filter section for the purpose of current smoothing on the output side of the AC/DC power converter 2.

However, if a filter capacitor is provided on the output side of the AC/DC power converter 2, for example, a polarity switching board corresponding to the inverse conversion operation of the power converter or a separate one used separately from the AC/DC power converter 2 is installed. This requires a power converter for regeneration, which increases the size of the power supply and increases its cost. (2) Furthermore, if the inductance of the electromagnet is larger, the accelerator cannot be operated in short cycles because the electromagnet current cannot move on to the next supply cycle until it completely falls to zero. The present invention was made to solve each of the above-mentioned problems, and is small and inexpensive, and can supply an electromagnetic current without ripple, and even if the inductance of the electromagnet is larger, it will not be necessary to carry out the next power supply cycle. The purpose is to provide an accelerator power supply device that can be quickly transitioned to the next generation. (Means for Solving the Problems) In order to achieve the above object, the first invention has a filter having a voltage smoothing reactor and a capacitor on the output side, and uses an AC to DC power converter for one power supply cycle. A power supply device that supplies direct current power to an accelerator electromagnet by performing a forward/inverse conversion operation inside the capacitor, the power supply device being connected in series with the capacitor and converting the power of the capacitor at the start of the forward conversion operation of the AC-to-DC power converter. a bipolar switch that is turned on to start charging and turned off during reverse conversion of the AC to DC power converter; and a bipolar switch that is connected in series to the electromagnet and that is connected to the electromagnet after the capacitor is charged to a predetermined value. The device is characterized by comprising a unipolar switch that is turned on to supply power to the device and turned off by the start of the next power supply cycle.

In addition, in the above power supply device, it is essential that the initial charging of the electromagnet current is completed before the start of the next power supply cycle, and the output current is completely reduced to zero before the start of the next power supply cycle. It is necessary to perform the initial charging after the initial charging is completed. Therefore, for example, in the case of an electromagnet with high inductance and a large discharging time constant, it takes time for the electromagnet current to fall, so it is important to ensure a sufficient initial charging period. There may be cases where this method cannot be applied to other power sources. In such a case, it is necessary to charge the capacitor more quickly. Therefore, in order to realize this high-speed charging, in the second invention, the capacitor is connected in parallel to the capacitor, initial charging of the capacitor is started during the reverse conversion operation of the AC-DC power converter, and the AC-DC power converter an initial charging power source that finishes charging the capacitor to a predetermined value by the start of forward conversion of the power converter; and an initial charging power source connected in series with the capacitor and turned on when forward conversion operation of the AC to DC power converter starts; The power converter is characterized by comprising a bipolar switch that is turned off during reverse conversion of the AC-DC power converter. (Function) In the first invention, first, before starting up the electromagnetic current, the bipolar switch connected to the initial charging capacitor is turned on. At this time, the AC/DC power converter is controlled so that a positive voltage appears at its output terminal, and the capacitor is charged to a desired voltage value depending on the load characteristics of the electromagnet. At this time, the unipolar switch is off, so no current flows through the electromagnet. Next, the unipolar switch provided between the filter and the electromagnet is turned on, and the electromagnet current starts to rise. At this time, the terminal voltage of the capacitor and the voltage of the AC/DC power converter output via the voltage smoothing reactor (both voltage values are the same) are applied to the electromagnet. Then, the electromagnet current rises linearly without ripple, and t! ! supplied to the magnet.

Next, when the electromagnet current reaches a predetermined maximum value, the electromagnet current starts to fall. At this time, the bipolar switch is turned off and the capacitor is disconnected from the electromagnet and the AC/DC power converter. The AC/DC power converter is then controlled so that a negative voltage appears at its output terminal, and the energy stored in the electromagnet is 'it!' It is regenerated to the source side.

In the second invention, charging of the capacitor is started by the initial charging power source while the electromagnet current is falling. The capacitor is then charged to the desired voltage value depending on the load characteristics of the electromagnet. Next, the AC/DC power converter operates,
The electromagnet current begins to rise. Then, the terminal voltage of the capacitor and the positive voltage of the AC/DC power converter outputted via the voltage smoothing reactor are applied to the electromagnet. By applying this voltage, the electromagnet current rises linearly without ripple and is supplied to the electromagnet. Next, when the electromagnet current reaches a predetermined maximum value, the electromagnet current begins to fall. Then, the bipolar switch is turned off, and the capacitor is disconnected from the electromagnet and the AC/DC power converter. At this time, the AC/DC converter is controlled so that a negative voltage is generated at its output terminal, and at the same time, the energy stored in the electromagnet is regenerated to the power supply side.
While this regeneration operation is being performed, the initial charging power source starts charging the capacitor in preparation for starting up the electromagnet current in the next power supply cycle. Thereafter, the same operation as above is repeated, and DC power is supplied in short cycles to the high inductance electromagnet with a large time constant.

(Examples) Examples of the first and second inventions will be described below with reference to the drawings. First, FIG. 1 is a configuration diagram showing an embodiment of the first invention.

The power supply device 6 in the figure consists of an AC/DC power converter 2, a filter 3 provided on the output side thereof, and a starting thyristor switch 5 as a unipolar switch.The filter 3 includes a reactor 3a, a capacitor 3b, It consists of a bipolar switch 3c and a reverse voltage prevention diode 3d. An AC power supply 1 is connected to the input side of the AC/DC variable Mi2, and an electromagnet 4 serving as a load is connected to the output side of the filter 3 via a starting thyrisk switch 5.

Bipolar switch 3 between noactor 3a and capacitor 3b
c is a reverse blocking type switch capable of self-turning, such as GT
O thyristor, SI thyristor, etc. In the figure, GT
O thyristor is shown. This bipolar switch 3C
performs initial charging to the capacitor 3b, turns on when the electromagnet current rises and rises (during forward conversion operation), discharges to obtain current accuracy of the rise of the electromagnet current, and discharges when the current falls (reverse conversion operation). (during conversion operation), the capacitor 3b is turned off.
It has the function of separating the circuit from the circuit. Further, the starting thyristor switch 5 between the power supply device 6 and the electromagnet 4 has a function of turning off at the time of initial charging and preventing discharge toward the electromagnet when the capacitor 3b is initially charged.

The operation of one power supply cycle of the above power supply device will be explained below with reference to FIG. At time h, at the same time as the AC/DC power converter 2 starts forward conversion operation, the bipolar switch 3C is turned on, and the capacitor 3
b is initially charged to the polarity shown in FIG. At this time, the starting thyristor switch 5 is off, and no power is being supplied to the electromagnet 4. Then, the starting thyristor switch 5 is turned on by the start signal at time t2, and power is supplied to the electromagnet 4.

By the way, what is the voltage between the terminals of the electromagnet 4, ignoring the voltage drop due to the resistance 4a of the electromagnet 4? i@L-■ dt, and 5 inductances 4b (its value is Lm) is a function of one electromagnet current. Therefore, the AC/DC power converter 2 must apply a voltage to the electromagnet 4 corresponding to the above-mentioned reverse voltage. iii.L near the start-up of the magnet current
．． Since can be a constant, the back electromotive force becomes a constant value, and the AC/DC power converter 2 performs current control according to the back electromotive force. Thereafter, when the inductance 4b becomes saturated, the value of L becomes smaller and the value of the counter electromotive force decreases. At this time, the AC/DC power converter 2 performs control according to the reduction in the back electromotive force.

Then, the current flowing into the electromagnet 4 rises to almost the maximum value at time t3, and then, at time t4, the bipolar switch 3C is turned off and the AC/DC power converter 2 is controlled to shift to reverse conversion operation. be done.

Thereafter, the energy accumulated in the coil of the electromagnet 4 is regenerated to the AC power supply 1 side via the power supply device 6, and again at time tx. & This returns to the corresponding time t1', and the same operation as above is repeated. Note that since only positive polarity voltage is applied to the capacitor 3b, a unipolar capacitor such as an electrolytic capacitor may be used as the capacitor 3b, but as shown in FIG.
In this case, it is safer to provide a protective diode 3d for preventing application of reverse voltage across both ends of the capacitor 3b.

Next, FIG. 3 is a structural diagram showing an embodiment of the second invention. In the power supply device 8 shown in the figure, a starting cylino between the filter 3 and the electromagnet 4 shown in the first invention,
The data switch 5 (see Figure 1) is not provided. Further, the capacitor 3b is provided with a power source for initial charging. In this embodiment, the initial charging power source is a power converter 7, whose AC side is connected to the AC power source 1. In addition,
Other configurations are the same as in Figure 1. Hereinafter, the operation of one power supply cycle of the power g device 8 will be explained with reference to FIG.

At time t1, the bipolar switch 3C is turned off, the power converter 7 for initial charging starts initial charging, and the capacitor 3b is initially charged to the polarity shown in FIG.

By the way, when the inductance of the tli magnet is higher, for example, the waveform of the electromagnet current has the characteristics shown by the dotted line in FIG. 2. In this case, in the first invention, it is necessary to delay the on-timing of the bipolar switch 3c shown in the figure to after time ts in the figure. The second invention is to perform initial charging of the capacitor 3b before the electromagnet current becomes zero in such a case. Therefore, the point in time when the power converter 7 for initial charging starts charging Jε is before the electromagnet current becomes zero, and the AC/DC power converter 2 is performing a reverse conversion operation. After time t0, the AC/DC power converter 2 is activated by the start signal at time t2, and the bipolar switch 3C is turned on.
Electric power is supplied to the electromagnet 4. Moreover, at the same time, the power converter 7 for initial charging shifts to an off (shift) state.

Then, as in the Lth invention, the current flowing into the electromagnet 4 rises to almost its maximum value at time ta. Thereafter, at time t4, the bipolar switch 3C is turned off, and the AC/DC power converter 2 shifts to an inverse conversion operation. After this, the energy corresponding to the inductance 4b is regenerated to the power supply side.

Then, during this current regeneration period, the power converter 7 for initial charging is operated again in preparation for startup in the next power supply cycle (
At time t1'), capacitor 3b is initially charged to the same value as last time, and operation in the next cycle is started. By repeating this operation, the power supply device 8
can be operated in short cycles.

(Effect of the invention) According to the first invention, a bipolar switch is connected to the initial charging capacitor that functions as a DC filter, and the switch is turned off when the electromagnet current falls. It has become possible to have the AC/DC power converter perform the role of regenerating power without causing a reverse voltage drop. Therefore, the capacitor may be a small, unipolar type, and furthermore, since there is no need to use a separate power converter for regeneration, the entire power supply device can be downsized.

Furthermore, in the past, the capacitor voltage was always completely discharged, but in the first invention, the voltage can be maintained at a certain level, so the cycle period of the electromagnet current can be shortened and high-speed repetitive operation is possible. It is possible to provide a power supply system iζt with high reproducibility and reliability. Furthermore, according to the second invention, since the power supply for initial charging is separately connected to the filter capacitor, the capacitor voltage can be charged to the required initial level during the current fall period (during the regeneration period). This has the effect of shortening the cycle period and enabling higher-speed repetitive operation without increasing the speed.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a power supply device showing an embodiment of the first invention, Fig. 2 is a waveform diagram showing voltages, currents, etc. of various parts in the embodiment of Fig. 1, and Fig. 3 is a circuit diagram of a power supply device showing an embodiment of the first invention. FIG. 4 is a waveform diagram showing the voltage and current of each part in the embodiment of FIG. 3, FIG. 5 is a circuit diagram showing a conventional power supply device, and FIG. 5 is a waveform diagram showing the output voltage and electromagnet current of the AC/DC power converter of FIG. 5. FIG. l... AC power supply, 2... AC/DC power converter, 3...
·filter. 3a...Reactor, 3b...Capacitor, 3c...Bipolar switch, 3d...Diode for preventing reverse voltage application, 4...Xfi magnet, 4a...
Resistance component, 4b...Inductance component, 5...Sirisk switch for starting, 6, 8... Power supply device, 7... Power converter for initial charging

Claims (2)

[Claims] (1) A power source that has a filter with a voltage smoothing reactor and a capacitor on the output side, performs forward and reverse conversion operations during one power supply cycle using an AC-DC power converter, and supplies DC power to the accelerator electromagnet. a device connected in series to the capacitor, turned on to start charging the capacitor when the forward conversion operation of the AC-DC power converter starts, and configured to turn on when the AC-DC power converter starts the reverse conversion operation; a bipolar switch connected in series with the electromagnet, which is turned on to supply power to the electromagnet after the capacitor has been charged to a predetermined value, and is turned off before the start of the next power supply cycle; A power supply device comprising a unipolar switch and. (2) A power source that has a filter with a voltage smoothing reactor and a capacitor on the output side, performs forward and reverse conversion operations during one power supply cycle using an AC-DC power converter, and supplies DC power to the accelerator electromagnet. The device is connected in parallel to the capacitor, starts initial charging of the capacitor during the reverse conversion operation of the AC-DC power converter, and charges a predetermined amount by the time the forward conversion of the AC-DC power converter starts. an initial charging power source that finishes charging the capacitor up to the initial charging value; and an initial charging power source that is connected in series with the capacitor and is turned on when the forward conversion operation of the AC-DC power converter starts, and that is turned on when the forward conversion operation of the AC-DC power converter starts. A power supply device characterized by comprising: a bipolar switch that is in an off state;