SU879520A1 - Device for measuring magnetic flux - Google Patents

Description

one

The invention relates to the control of AC drives and can be used in variable frequency drive systems to produce signals proportional to the magnetic flux of an AC electrical machine. These signals can be used both to study the magnetic field of a machine and to build a machine control system.

A device comprising a measuring winding connected to the flow integrator input, a control unit, three keys, an operating amplifier, and an amplifier is known. In this case, the flow integrator input through one switch and operational amplifier, and the output through another switch are respectively connected to the output and input of the drift zero integrator, parallel to which the third switch l is connected.

However, the known device works with high precision ONLY in a narrow range of measured frequencies. As the range expands, the accuracy of the work drops sharply, and therefore when using the device in electric machines that operate in wide

frequency range, it does not provide the required accuracy.

The aim of the invention is to improve the measurement accuracy and expand the range of operating frequencies.

The goal is achieved by the fact that a device for measuring the magnetic flux containing a metering winding connected to the input

10 flow integrator, controllable keys, a drift zero integrator, in parallel with which a key for setting zero initial conditions is connected, a control unit, a product block is entered and a block is defined11 of the signal frequency, the input of which is connected to the input of the drift integrator zero through the first control key The second control key is connected with. input and integrator qoTO20 ka.

The drawing shows the functional diagram of the device.

The device consists of a measuring winding 1, a flow integrator 2, a product block 3, a control key 4, a drift integrator zero 5, a key for setting zero initial conditions 6, a control key 7, a block

30 determine the frequency 8 performed

in the form of a controllable key 9, a functional converter 10, an integrator of a period 11, a key 12 for setting zero conditions, a controllable key 13 and a signal conditioner 14, a block 15 for managing keys.

The measuring coil 1 is connected in series with the flow integrator 2, the output of which through one input of the product block 3 and the control key 4 is connected to the drift zero integrator 5, in parallel to which the zero setting key 6 is connected. The output of the drift integrator zero 5 is connected via the control key 7 with the input of the flow integrator 2. The other input of the production unit 3 through the control key 9 is connected to the functional converter 10, the input of which is connected to the output of the period 11 integrator. Parallel to the integrator 11 on A yuchen key 12 for setting zero conditions, and an integrator 11 via a controllable key 13 and a driver siggshov 14 is connected to the output of the flow integrator 2. The input of the key management unit 15 is connected to the output of the flow integrator 2.

A device for measuring the magnetic flux works as follows. On measuring winding 1, a signal is generated that is proportional to the derivative of the measured flow. This signal is fed to the input of flow integrator 2, and a signal proportional to the measured flow is generated at the output of the integrator. This signal is superimposed by the drift of the zero integrator, which will accumulate if not compensated. To compensate for the drift, the zero of the flow integrator 2, the output of the integrator 2 through the product block 3 and the control key 4 is fed to the input of the drift integrator zero 5, which always starts working under zero initial conditions and operates on a time interval equal to an integer number of periods (in particular one period) of the signal produced by the integrator flow 2. Zero initial conditions for the operation of the drift integrator zero 5 are provided by pre-locking the key to set the zero initial conditions 6. Then the signal obtained at the output of the integral the drift rator zero is proportional to the drift zero flow integrator 2

After the signal proportional to the zero drift is formed, the control key 4 is opened and the key 7 is closed, and in this interval of operation the drift zero of the flow integrator 2 is compensated. Then the key 7 is opened and the key sets the zero initial conditions 6. In order for the device to work stably at different frequencies, it is necessary to vary the gain of the compensation circuit. Therefore, a signal of the form N) () I 2, proportional to the frequency of the measured signal, is supplied to the second input of the product 3 through the control key 9 from the functional converter 10. The input of the functional converter 10 is supplied with a signal proportional to the period of the signal under study, generated by the integrator of period 11, which is connected to the output of the integrator of flow 2 via controlled switch 13 / signal conditioner 14, and parallel to the integrator 11 is set zero setting conditions 12.

0 Key 9 closes simultaneously with key 7, key 13 simultaneously with key b.

The key management unit 15 receives clock pulses directly from the output of the stream integrator 2.

The use of the invention will simplify the known device, improve the accuracy of measuring the magnetic flux, and extend the range of operating frequencies by at least 10-20 times. Applying the invention to an AC drive control system will improve drive accuracy.

Claims (1)

1. For the number № 2780660 / 18-21, cl. G 01 R 33/02, 1979 (prototype).