JPS5935525A - Overload detecting circuit for short time capacity device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an overload detection circuit for short-time capacity equipment, particularly for overload detection of short-time capacity controlled rectifiers used in nuclear fusion power sources, etc. It is related to circuits.

[Technical background of the invention]

Tokamak-type fusion reactors are currently considered to cause fusion reaction intermittently, and a controlled rectifier that is operated intermittently is used as a power source for plasma control. When designing a controlled rectifier such as this, calculate the temperature rise during short-time energization and temperature drop during non-operation periods, and ensure that the temperature of the controlled rectifier element remains below the allowable value in any required operating pattern. Design it like this. ~In the case of nuclear fusion power supplies, they may still be operated continuously at a low level of current in order to bake the vacuum chamber that confines the plasma. Fig. 1 shows the load current waveform during intermittent operation, and Fig. 2 shows the load current waveform during continuous operation. Further, during the pause period of the intermittent operation shown in FIG. 1, operation with a low level current may be performed.

[Problems with background technology]

For this reason, in order to protect the conventionally controlled rectifier, each operation of the J? In addition to changing the overcurrent set value for each turn, the allowable values for energization time and rest period are determined for each operation pattern, and if the energization time exceeds a certain value or the rest period is short, an overload is detected. It was detected as. However, nuclear fusion is currently still under development, and the control rectifiers used for it are designed to operate in various patterns, and it is not possible to change the set value of the protection detector for each operation pattern. There are problems in that it is complicated and reliability is significantly lowered.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems in the overload detection method for short-term capacity equipment, particularly nuclear fusion power supplies, and to provide a simple and reliable overload detection circuit for short-term capacity equipment.

[Summary of the invention]

The present invention includes a first integrating circuit with a limit that integrates the current with a long time constant during continuous operation and fixes it at a value corresponding to the saturation temperature of the control rectifying element, and A second integrating circuit is provided that discharges the heat capacity of the device to a predetermined value when the temperature falls below a certain level. It is designed to detect overload.

[Embodiments of the invention]

FIG. 3 shows a block diagram of an embodiment of the present invention. In FIG. 3, '1' represents the above-mentioned integration circuit 1, and 2 represents the above-mentioned second integration circuit.

5-1 is an amplifier constituting the first integrating circuit, 7-1 is an input resistor R, and 8-1 is a feedback capacitor C-.
It's 1. Reference numerals 9-1 and 9-2 are analog switches that are opened and closed by the start/stop command 54, and 4-1 is a setting device that determines the slope of discharge of the first integrating circuit 1. Reference numeral 51 indicates a load current value, and 52 indicates an output value of the first integrating circuit 1.

6 may be a limiter that sets a limit value on the output value of the first integrating circuit, a constant voltage diode, or a known limiter circuit using a diode is sufficient. 3-1
7-2 is a level detector that detects the value of the load current and controls charging and discharging of the second integrating circuit, and 7-2 is a charging resistor R2, 7.
-3 is a discharge resistor R3, 4-3 is a setting device that determines the slope of discharge, 5-2 is an amplifier, 8-2 is a feedback capacitor C-2, and 04-4 is a level detector 3-1. Setting devices 9-3 and 9-4 for determining the level are analog switches whose opening and closing are controlled by the output of the level detector 3-1.

5-3 is an amplifier for calculating the sum of the first integrating circuit 1 and the second integrating circuit 2; 3-2 compares the output value of the amplifier 5-3 with the value of the setting device 4-2; This is a level detector that outputs an overload signal if it is larger than the set value. 7-4 to 7-6 are resistors.

The present invention will be explained in detail below with reference to FIG.

When the load current value is smaller than the continuous rated current value, when the start/stop command 54 is activated, the analog switch 9-1 closes and 9-2 opens, and the load current is reduced by the first integrating circuit 1. is integrated and limited to the value set by the limiter 6. If the load current is rd, the integral output 52 is Ed1=
Id・t/RICI. The RICI is determined by the heat capacity of the control rectifier and cooling fins, and is set to be equal to or longer than the time at which the temperature of the control rectifier is saturated. Edl limiter value EdIL
is equivalent to the saturation temperature TIA of the control rectifier during continuous operation. In other words, the maximum allowable temperature of the control rectifier is TMA
Let X be the current of seven times. Setting device 4-2 is EMA
Set to X. During normal operation, Ed I L (EMAX
With reeds, it is operated normally.

Start/stop command 54. When it stops, the analog switch 9-1 is opened and the analog switch 9-2 is closed, causing discharge according to a predetermined slope.

Next, in the case of intermittent operation as shown in Fig. 1, when the load current becomes larger than the value of the setting device 4-4 which sets the continuous rated current value, the output of the level detector 3-1 will change. “1
# When analog switch 9-3 is closed and analog switch 9-4 is open, the load current is integrated by the second integrating circuit, and its output 53 is Ed2 = Id-t/R2C2 (! :
fx le.

R2Cz << RICI is set so that the output of the first integrating circuit Ed1 can be ignored for a short time. When the load current becomes smaller than the setting value of the setting device 4-4, the analog switch 9-3 opens and 9-4 closes.
υ is discharged according to the slope determined by R8C2 and the set value 4-3. R3C2 is determined according to the temperature drop characteristics of the controlled rectifier. FIG. 4 shows the value of the integral output value 52 in the case of continuous operation mode, and FIG. 5 shows the value of the integral output value 53 in the case of intermittent operation.

As described above, the first integrating circuit and the second integrating circuit are provided,
If the setting device 4-2 is set to EMAX as described above, during intermittent operation, if the energization time is longer than the specified value, Ed
, ≧EMAX, overload can be detected. Furthermore, if the downtime is shorter than a predetermined value, Ed2 will not become zero at the start of energization, so if Ed≧EMAX during energization, an overload will be detected.

In addition, when low-level operation is performed during the pause period of intermittent operation, the sum of the temperature rise value due to low-level operation and the temperature rise due to short-time operation is the maximum allowable temperature TMA of the control rectifier.
It must be less than or equal to X, so gdl '+ rd2
If the current level and operating time during short-time operation are not set so that <, EMAX, it will be detected as an overload.

〔Effect of the invention〕

As explained above, when the overload detection circuit for short-time capacity equipment of the present invention is used, the operation/J? Overloads can be easily detected for short-time capacity equipment based on the design value of the heat capacity of the equipment, without changing the overcurrent set value, abnormality detection value for energization time, and abnormality detection value for down time for each turn. A load detection circuit can be provided.

[Brief explanation of drawings]

Figure 1 is a load current waveform diagram during intermittent operation, Figure 2 is a load current waveform diagram during continuous operation, Figure 3 is a plot diagram showing an embodiment of the present invention, and Figure 4 is a continuous load current waveform diagram. Figure 5 is a characteristic diagram showing the relationship between the load current waveform diagram during operation and the output of the first integrating circuit in Figure 3; FIG. 3 is a characteristic diagram showing the relationship with the output of the integrating circuit. 1... First integrating circuit, 2... Second integrating circuit, 3
-113-2... Level detector, 4-1 to 4-4...
・Setting device, 5-1 to 5-3...Amplifier, 6...Limiter, 7-1 to 7-5...Resistor, 8-1 to 8-i・
...Capacitor, 9-1 to 9-4...Analog switch. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 [4-4 Figure 4 Figure 5

Claims (1)

[Claims] The first circuit integrates the load current and is limited at a certain level.
and a second integrating circuit that integrates the load current when the load current exceeds a certain level, and discharges at a preset value depending on the heat capacity of the device when the load current is below the certain level. 1. An overload detection circuit for short-time capacity equipment, characterized in that an overload state is detected when the sum of the outputs of a first integration circuit and a second integration circuit becomes larger than a predetermined value.