SU1464275A1 - Electric drive control system - Google Patents

Abstract

The invention relates to electrical engineering, in particular to electric water, and m. used in the construction of high-quality positional software control systems with direct and alternating current electric drives. The purpose of the invention is to improve the accuracy of positioning and the quality of transients in the drive. The control system contains a software setting device 1, the job code of which, through the input unit 2, is recorded in the reversible counter 3. Distinguish between the mode of testing large displacements in the process of reaching the steady-state speed and the mode of testing small displacements. The latter is characterized in that the voltage of the Converter 4, the code voltage, becomes less than the voltage of the converter 12, the frequency-voltage before the output of the electric drive at a steady speed. In this case, the transmission coefficient of converter 12 is chosen such that the moment of switching to braking corresponds to working off half of the specified movement (at the same intensity of start and braking). In this case, overshoot or inhibition during positioning is excluded, which increases the quality of transients and accuracy. 1 il. i O)

Description

four

9) 4a

you ate

The invention relates to electrical engineering, in particular to electric drives, and can be used in the construction of high-quality software control systems with direct and alternating current electric drives.

The aim of the invention is to improve the accuracy of positioning and the quality of transients in the drive.

The drawing is a diagram of a control system for an electric drive.

The control system for the electric drive contains, at the input, a software setting device 1, the output of which through the node 2 of the input is connected to the reversing input. the counter 3, the converter 4 code - voltage is connected through the position controller 5 to the switching contact of switch b connected at the output of the control system connected to the analog part 7 of the electric drive with the gearbox 8, on the output shaft of which the actuator 9 is installed with the displacement sensor 10, the output connected to the feedback input of the control system, which is the input of the pulse former 11, the outputs of which are connected to the addition and subtraction inputs of the reversing counter 3, successively connected a - user 12 voltage frequency, adder 13, relay element 14, intensity master 15, as well as logic elements 2ILI 16, where n is the code voltage converter 4, code-voltage, and logic element t-OR 17, where m - the number of bits of the reversible counter; 3, the higher ones. The outputs of the lower bits of the reversible counter 3 are alternately connected to one input of logic elements 2LI 16, and the outputs of m high-order bits to inputs of a logical element t-OR 17, the output of which is combined with others the inputs of logic elements 2ILI 16, the outputs of which are Switched to the corresponding bits of the converter 4 code - voltage, the higher bits of which are connected to the inputs of the switch 6. The output of the intensity setter 15 is connected via the disconnecting contact of the switch 6 to the input of the analog part 7 of the electric drive. The second input of the adder 13 is connected to the head of the converter

five

0

five

0

five

0

five

0

five

The 4th code caller is the voltage, and the inputs of the 12th frequency-voltage converter are connected to the high-voltage driver 11 pulses.

Switch 6 contains a series-connected logical element OR NOT input, amplifier and relay.

The control system for the electric drive works as follows.

Consider the operation of the system during the processing of large displacements, which is characterized by the output of the electric drive in the process of working at a steady rate. The task code for movement by input node 2 from software setpoint 1 is recorded in reversible counter 3. If at least one of the high bits of counter 3 is in the logical 1, t, o state, regardless of the state of the low-order bits voltage maximum signal level. Due to this on. The output of the adder 13, which determines the difference between the voltage of the converter 4 and the voltage of the converter 12 (the latter is proportional to the square of the pulse frequency or the square of the drive speed), a positive voltage appears and the relay element 14 switches to the positive saturation state . As a result, the setting device 15 forms the acceleration process of the drive, and after reaching the set value, the displacement processing continues already at maximum speed.

As the positioning point approaches in all higher bits of the counter-3, a low level (logical O) is set, as a result of which the lower bits of counter 3 are connected to the bits of the code-voltage converter 4. The voltage of the converter 4 begins to decrease, and the sign of the voltage at the output of the adder changes accordingly. 13, the relay element 14 reverses its state and the intensity setter 15 forms the drive braking process. As the actuator approaches the positioning point and the drive speeds to zero, the higher bits of the code-voltage converter 4 are zeroed, resulting in a switch 6 relay and switching the input to

3

the den part 7 of the electric drive system from the intensity setter 15 to the output of the positioner 5. The latter forms the final positioning process.

The small displacement mode is characterized in that the voltage of the converter 4 becomes less than the voltage of the converter 12 before the drive reaches a steady-state speed. In this case, the gear ratio of the converter 12, the frequency-voltage is chosen such that the moment of switching to braking corresponds to working off half of the specified movement (at the same intensity of start and braking). In this case, overshoot or inhibition during the positioning process is excluded.

The voltage at the ups of the frequency-voltage converter 12 can be written as follows:

and

HRC „Oi.otjCO,

(one)

where oi, is the transfer coefficient of the frequency-voltage converter 12;

oti is the transmission coefficient of the pulse feedback sensor 10;

CO - drive speed. When working out small displacements, the path traveled at the moment of switching is equal to half of the specified or

Y2

2a

 2

)

(2)

where a is the specified acceleration (deceleration) of the drive; Cf, is the given path.

Dp of the moment of switching, you can write the expression for the voltage converter 4

,-one;)-,

 Soy, oij.

and

bee

(3)

position feedback channel gain. (2) and (3) together, you can

 Wot3 2aabg

(four)

Substituting (4) in (1) we get

and

Pci

C02

(five)

ten

Thus, when working out large and small displacements with a drive, a frequency-voltage converter with a quadratic relation between the input and output signals is necessary. If the drive is intended for testing, only large movements, then it suffices to choose

oi,

G) CT 3

2a

(6)

Thus, in the control system for the electric drive, the formation of the start and deceleration modes of the drive is carried out by the intensity adjuster, and the start of deceleration is automatically determined depending on the remaining working path, the current speed of the electric drive and the set deceleration intensity, this increases . The analog position controller is operated directly at the positioning point at a drive speed close to zero, which makes its calculation and implementation, and hence the accuracy of operation, much simpler, which leads to an approximation of the real characteristics of the positioning process to calculated ones and a decrease in positioning error.

Claims (1)

Invention Formula The control system for the electric drive, containing at the input a program setting device, the output of which through the input node is connected to the input of the reversible counter, the converter code - voltage through the position controller connected to the closing contact of the switch connected at the output of the control system, the sensor movement of the executive body, the output connected to the input of the pulse shaper, the outputs of which are connected respectively to the inputs of the addition and subtraction of the reversing counter, characterized in that, in order to improve the positioning accuracy and quality of the switch. processes in the electric drive, a series-connected frequency converter — voltage, adder, relay element, intensity adjuster, and logic elements 2 OR, where n is the code-voltage converter voltage, and a t-OR logic element, where m is the number of bits of the reversible counter, the higher n, while the outputs n of the lower bits of the revision counter are alternately connected to one input of the logic elements 2ShSh, and the outputs m of the highest discharge - to the inputs of the logic element t-ШШ, the output of which bedinen with other inputs of gates 2or outputs .kotoryh sootvetstvuyuptst connected to n bits of the pre-code-forming voltage, older bits of which are connected to the inputs of the switch, the output ramp through normally closed switch contact connected to the output the control system, the second input of the adder is connected to the output of the code-voltage converter, and the inputs of the frequency-voltage converter are connected respectively to the outputs of the pulse former.