SU1363161A1 - Device for regulating pump pressure - Google Patents

Abstract

The invention relates to a technique for the automatic control of electric motors of centrifugal pumps. The aim of the invention is to increase the noise immunity of the proposed device. The device for controlling the pressure of the pump contains a sensor 8 and a pressure setting device 1, a key element 3, an integrator 4, a control unit 5 for an electric motor, an electric motor 6, a pump 7, a speed sensor 9, a zero-organ 10, a stabilization signal generating unit 11 and an error estimation unit 12 . 1 il. SB (L with O5 with C5

Description

This invention relates to automatic control and can be used in automatic electric drive systems for high-power centrifugal pumps in industry and public utilities.

The purpose of the invention is to improve the noise immunity of the device for regulating the pressure of the pump.

The drawing shows a functional block diagram of the proposed device.

The device contains an output parameter setting device 1, an adder 2, a key element 3, an integrator 4, a motor control unit 5, an electric motor 6, a pump 7, as well as a pressure sensor 8, a motor speed sensor 9, a zero-body 10, a stabilizing signal generating unit 11, block 12 error estimates.

The device works as follows.

When the pressure detected by pressure sensor 8 increases, the difference between the signal of parameter setpoint 1 and pressure sensor 8 from adder 2 is fed through key element 3 to integrator 4. The control voltage that flows to integrator 4 increases at the output of integrator 4, the latter influences electric motor 6 leads to an increase in the frequency of rotation of the pump 7. The device operates with a small steady-state pressure deviation.

With a sharp decrease in the flow rate, for example, as a result of a large number of consumers disconnecting due to the repair of the hydraulic network section, the pressure starts to increase, the control voltage at the integrator output drops; the frequency of the vrash, the electric motor also falls. As a result, the required pressure level is restored. But the control voltage due to the inertia of the engine-pump-hydraulic system is less than that required for quasi-established work. This can cause a lot of overshoot and fluctuations. Under these conditions, the device operates as follows. The stabilization signal generating unit 11 converts the speed data of the electric motor 6 coming from the motor speed sensor 9 into a control voltage at which this speed remains constant in the case of a constant load. The error estimator 12 compares the control voltage at the output of blocks 11 and 4. If the difference between them exceeds the magnitude of the possible error with which the stabilizing signal generating unit 11 generates a control voltage, the error estimator 12 sends a signal to the control input of the key element . When the signal from the adder 2 is zero, the zero-organ 10 delivers a short control pulse, the duration of which is determined by the necessary recharge time of the capacitor of the integrator 4, to the second control input of the key element 3. If there is a signal from both block 10 and block 12 the key element 3 connects to the integrator 4 a block 11 for generating a stabilizing signal. At the output of the integrator 4, a control voltage is set equal to the signal from block 11. This limits the amount of overshoot pressure. Further operation of the circuit is similar to that described above. At low rates of change in the supply, when the overshoot cannot be more, it is not necessary to connect the stabilization signal generating unit 11 to the integrator 4; such a connection does not allow block 12 error estimates.

Technical and economic efficiency of the proposed device is achieved by

0 by eliminating the influence of continuously varying derivative of pressure on the operation of the device with a smooth change in flow rate, which eliminates the mode of constant switching in the device and increases

5 its noise immunity. The testing of large discrepancies occurs with a free change in the control voltage, and the exception of a large amount of overshoot occurs due to a sudden change in the control voltage with equal set and actual pressure, which increases the speed while maintaining quality indicators.

Claims (1)

Invention Formula A device for controlling the pressure of the pump, comprising a series-connected pressure setting device, an adder, a key element, an integrator, a motor control unit, an electric motor, a pump and a pressure sensor, an output connected to the second input of the adder, and the second input of the control unit is connected to the output of the engine speed sensor. - that, in order to improve noise immunity, it additionally contains a null body, a series-connected stabilization signal generation unit and an evaluation unit error, and the input unit of the formation of the stabilizing signal is connected to the output of the sensor speed, and the output through the second group of closing contacts of the key element - with the installation input of the integrator, the first control input of the key element is connected to the output of the null organ, and the second control input - with the output of the error evaluation unit, the second input of which is connected to the output of the integrator, the input of the zero-organ is connected to the output of the adder.