JPS63289614A - Magnetic flux control circuit - Google Patents

Abstract

PURPOSE:To compensate delay of an eddy current at high speed by comparing a magnetic flux simulation value obtained from a simulation circuit of an electromagnet with a practical value, setting up a feedback circuit so as to be driven similarly to the practical circuit and adding a differential value of an effective current relating to an obtained eddy current time constant to a command value to obtain an effective current command value. CONSTITUTION:Magnetic flux phi is detected by a magnetic flux detector 4, in a simulation value obtained through a simulation circuit consisting of a multiplier 51B, and an integrator 53A, a deviation (e) between the simulation value and the value phi is extracted through the adder/subtractor 54C, multiplied by the simulation value by means of a multiplier 51C and integrated by an integrator 53B and the integrated value is inputted to the multiplier 51B. At that time, the output (a) of the integrator 53B corresponds to an eddy current time constant. The input of the integrator 53 is always supervised by a comparator 56, a switch is opened/closed and the value (a) corresponding to the eddy current time constant is stored in the integrator 53B. In said constitution, a delay due to the eddy current can be compensated without executing measuring/adjusting work, a sharp pulse-like magnetic flux is obtained, and even if a coil having the temperature change of a resistor or a different time constant is used, adjustment in each change can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control circuit for supplying a predetermined current to an electromagnetic coil to generate a predetermined magnetic flux.

[Conventional technology]

When a predetermined current is supplied to an electromagnetic coil to generate a predetermined magnetic flux, an equivalent circuit of the electromagnetic coil is expressed as shown in FIG. Here, R1 is the coil resistance, R2 is the eddy current product equivalent resistance, L is the coil inductance, 1 is the current supplied to the coil (coil current), IR is the eddy current product equivalent current, IL is the coil effective current, and φ is Magnetic flux (=LiL).

In order to generate such magnetic flux, conventionally, for example, a third
As shown in the figure, a constant current control loop is constructed by a current regulator 1, a power amplifier 2, and a current detector 6, and a coil current i is made to match a command value l to generate a constant magnetic flux φ. There is.

Here, the following relationship holds true between the current i and the effective current 9 for creating the magnetic flux φ: (S is the Laplace operator). Therefore, when trying to obtain a pulsed magnetic flux, the IL responds with a -second lag time constant due to the eddy current product, so the change in magnetic flux φ is delayed with respect to the pulse 'tEIfi,i. Become. However, since fast magnetic flux control is not possible, in order to compensate for this time exposure, the coil 7IL flow command value l is set to 1 = (1+5TF
)1 (2) A leading filter 7 having a transfer function is inserted so that TF=TI, thereby canceling out the delay caused by the eddy current.

[Problem that the invention seeks to solve]

However, since the value of the time constant TE differs for each coil to be controlled, it is necessary to accurately measure it each time, and it is possible to select from several types of filters with different adjustment ranges. Keep it like this, T
There is a problem that the adjustment becomes complicated because it is necessary to select and adjust the TF according to the measurement result of E. In addition, if a magnetic flux control loop is provided outside the current control loop shown in Figure 6, a magnetic flux detector is required to detect the magnetic flux, but this is expensive and difficult to install, so the time constant It is desirable to use it only when necessary, such as when calculating.

Therefore, this invention does not require adjustment of the eddy current time constant, allows the magnetic flux to follow its target value (command value) at high speed, and allows the magnetic flux detector to be removed after calculating the time constant. The purpose of this invention is to provide a control circuit that is easy to use.

[Means for solving problems]

a first simulation circuit that simulates the magnetic flux or effective current of the coil, which is made up of a series circuit of a multiplier and an integrator in order to supply a predetermined current to the electromagnetic coil and generate a predetermined magnetic flux;
a multiplier that multiplies the deviation between the simulated magnetic flux value simulated in the first simulation circuit and its actual value by the simulated magnetic flux value; and a multiplier that integrates the output of the multiplier and outputs a value equivalent to an eddy current time constant. an integrator, a second simulation circuit that simulates the actual directivity from the coil current command value, and an output from the second simulation circuit and the first simulation circuit.
an adder/subtracter that extracts the deviation from the output from the simulated circuit; an introduction circuit that introduces the output of the adder/subtractor and the output of the integrator into a multiplier in the first simulation circuit; an arithmetic circuit that calculates a current command value by multiplying it by a current command value and adding it to a coil effective current command value; a removable magnetic flux detector that detects the actual magnetic flux; and an output of the integrator. A holding circuit is provided, and after obtaining a value equivalent to an eddy current time constant using a magnetic flux detector in advance, this is held by the holding circuit, thereby making it possible to remove the magnetic flux detector.

[Effect]

Comparing the simulated magnetic flux value obtained through a simulated circuit of an electromagnetic coil with an eddy current product and the actual magnetic flux detected by a detector placed in a magnetic field, the simulated circuit is compared to the actual coil. Set up a feedback loop that operates in the same way, and add the differential value of the coil effective current related to the eddy current time constant obtained at that time to the coil effective current command value to obtain the coil current command value. Make work unnecessary,
By quickly compensating for the eddy current delay and holding a value equivalent to the eddy current time constant in the holding circuit,
Enables removal of magnetic flux detector.

〔Example〕

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

In the figure, 1 is a current regulator, 2 is a power amplifier, and 3 is a current regulator.
is an eddy current equivalent circuit, 4 is a magnetic flux detector, and 5 is a multiplier 51.
A, 51B, 51C, first-order lag element 52, integrator 53A
, 53B, adder/subtractor 54A.

54B, 54C, switch 55 and converter 5
This is a current command calculation circuit such as No. 6.

A search coil is placed in the magnetic field, and the magnetic flux φ is detected by a magnetic flux detector 4 that integrates the voltage induced therein.
A simulation circuit that simulates the above equation (1) is formed by the multiplier 51B and the integrator 53A, and the simulated magnetic flux value φ (the simulated value is indicated by a "△" mark) obtained through this simulation circuit and its actual value are The deviation e from the value φ is taken out via the adder/subtractor 54C. This deviation e is multiplied by the magnetic flux simulation value φ in a multiplier 51C, integrated by an integrator 53B, and then given as one multiplication input of a multiplier 51B in a simulation circuit that simulates 8 errors caused by eddy currents. . In this way, the integrator 53
The output a of B (equivalent to the eddy current time constant) is a=1/Tx (
6) can be derived from the known adaptive control theory. Then, if we focus on the relationship between the input and output of the simulated circuit, and transform this, we get . At this time, the following can be obtained from the input/output relationship of the eddy current equivalent circuit 6. Similarly, from the input/output relationship of the adder/subtractor 54B, the following can be obtained, and from the input/output relationship of the multiplier 51C and the integrator 53B, I can be obtained. Therefore, at t−+oo, φ=φ, 1
/a=TE. That is, the output of the integrator 53B has a time constant T
A simulation [a (= 1/TE) equivalent to I will be obtained. It is assumed that the actual coil current value iFi, which is input to the simulation circuit, is given by the output of the first-order lag element 52 that simulates the current control loop consisting of the regulator 1 and the power amplifier 2 with equal constraints. In addition, the input X of the multiplier 51B is (Y is another input of the multiplier 51B, and Y=a), so it can be considered that the multiplier 51A and the adder/subtracter 54A By performing the calculation +5TEl -i and setting 1 as the coil effective current command value,
A filter equivalent to the filter 7 shown in FIG. 3 can be obtained by the current command value calculation circuit 5.

In addition, the input of the integrator 53B is constantly monitored by the comparator 56, and when the input becomes @0'', the switch 55 provided on the input side of the integrator 53B is opened.
The output of B is maintained at that time. As a result, since the eddy current time constant flEa is stored in the integrator 55B, the magnetic flux detector 4 is not necessary) and can be removed in subsequent operations. By making the magnetic flux detector 4 removable in this manner, problems regarding installation space can be eliminated, and the configuration can be simplified and costs reduced.

〔Effect of the invention〕

According to this invention, since the eddy current time constant (equivalent l) is determined by calculation, the delay due to eddy current is compensated for and the start-up time constant is calculated without having to measure and adjust it.
, it is possible to create a pulsed magnetic flux with a steep fall. There is also the advantage that there is no need to adjust each time the coil resistance changes due to temperature or the coils have different time constants. Furthermore, since the calculation result of the eddy current time constant is stored, the magnetic flux detector can be removed thereafter, making it possible to simplify the configuration and reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram showing an electromagnetic coil, and FIG. 3 is a circuit diagram showing a conventional example of the antibacterial circuit. Description of symbols 1...Current regulator, 2...Power amplifier, 3...Twis'tIf, current equivalent circuit, 4...
...magnetic flux detector, 5... flow command value calculation circuit inside,
6...itt flow detector, 7...filter, 51A, 51B, 5jC...multiplier, 52
...First-order delay element, 53A, 53B...
・Integrator, 54A, 54B, 54C-time addition/subtraction unit, 5
5...Switch, 56...Comparator.

Claims (1)

[Claims] In order to supply a predetermined current to an electromagnetic coil and generate a predetermined magnetic flux, there is provided a first simulating circuit that includes a series circuit of a multiplier and an integrator and simulates the magnetic flux or effective current of the coil. , a multiplier that multiplies the deviation between the simulated magnetic flux value simulated in the first simulation circuit and its actual value by the simulated magnetic flux value, and integrates the output of the multiplier to output a value equivalent to an eddy current time constant. an integrator; a second simulation circuit that simulates the actual value from the coil current command value; an adder/subtractor that extracts the deviation between the output from the second simulation circuit and the output from the first simulation circuit; an introduction circuit that introduces the adder/subtractor output and the integrator output into a multiplier in a first simulation circuit; and a current command value by multiplying the adder/subtractor output by a coil effective current command value and adding this to the coil effective current command value. an arithmetic circuit that calculates the actual value of the magnetic flux; a removable magnetic flux detector that detects the actual value of the magnetic flux; and a holding circuit that holds the output of the integrator. A magnetic flux control circuit characterized in that, after the magnetic flux detector is obtained, the magnetic flux detector can be removed by holding it in the holding circuit.