SU1002965A1 - Device for measuring dc electrical machine armature angular speed - Google Patents

Description

(54) DEVICE FOR MEASURING ANGULAR VELOCITY OF AN ANCHOR OF ELECTRIC DIRECT CURRENT MACHINES

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The invention relates to a control and regulation technique and can be used to measure speed in systems for regulating, stabilizing and indicating speed.

Currently, the most widely used for measuring the speed of various kinds of sensors and. devices connected to the engine m 1 and 2.

However, these devices require mechanical communication with the monitored object.

The closest to the invention to the technical essence and the achieved result is a device for controlling the speed of the engine, in which an AC pulsation from the circuit that feeds the DC motor from the isolation transformer comes from the circuit that feeds the DC motor. The output of the driver is connected to the input of the storage device, the output circuit of which is connected to the speed indication circuit. The full-wave rectified alternating voltage is fed to the input of the synchronization unit. The output of this unit is connected to the input of a timer, the output circuit of which is connected to the control input of the one-shot. One output one jj of the vibrator is connected to the transfer circuit of the pulse counter of the storage device, and the other to the output circuit of the information updating device, the output of the latter being connected to the memory cleaning input.

. The sensor allows you to measure and display the integral value of the angular velocity of the core of the DC motor, while the delay in the measurement system can be from 1 to 9 s Sz. The drawbacks of the device are the low accuracy of measuring the angular velocity due to the demagnetizing reaction of the core (mainly for low-power electric machines), low response time due to the long period of measuring the angular velocity, the narrow range of application due to the large delay in the measurement system, eliminates its use in automatic control devices for regulating and stabilizing the angular velocity. The aim of the invention is to improve the speed, accuracy of measurement and the expansion of the scope. The goal is achieved in that the first memory device, an indicator and a synchronization unit connected to the power circuit of the electric machine are entered into a device containing a pulse generator connected to the electric machine's main circuit, a second memory device and a switch, while the input of the key circuit is connected to the output of the imager, the outputs of the key circuit are connected to the information inputs of the first and second memory devices, their outputs are connected via a commutator to the indicator, the second input the synchronization unit is connected to the output of the imaging unit, the outputs of the synchronization unit are connected to the control inputs of the first and second memory devices and the switch. Moreover, a one-shot and a logic multiplication circuit are inserted into the device, while the input of the one-shot and the first input of the multiplier circuit are not connected to the output of the driver logic multiplication circuits - to the one-shot output, and the logic multiplication output to the key circuit input. In addition, in order to reduce the inductance of the core circuit in devices administered monostable multivibrator, DEPT pulse and a coincidence circuit, wherein the input of the monostable is connected to an output of the pulse counter input and the first input of a coincidence circuit connected to the output of the monostable, the second input of the coincidence circuit is connected to the output of pulse counter and the output cxeNW matcher connected to the input key scheme. Fig. 1 is a block diagram of a device for measuring the angular velocity of the core of an electric DC machine; in fig. 2 and 3 are structural diagrams of modifications of this device, in fig, jt - diagrams of operation of individual units of the device, in figo 7 dependencies, explaining the principles of construction of the device and its individual blocks. the synchronization unit 2 and the input of the key circuit 3 "One output circuit of the key circuit 3 is connected to the information input of the memory A, and the other to the information input of the memory 5" The output of the memory 4 is connected to one Valid at switch 6 and the output circuit of the memory device 5 is connected to the other input of the switch 6, the output of which is coupled to the input of the display 7. In this case, one output of synchronization unit 2 is connected to the control input of memory 4, the second to the enabling input of switch 6 and the third to the control input of memory 5 The device (Figo 2) additionally contains a one-shot 8 and a logical multiplication circuit 9, which are included between the pulse shaper 1 and the key circuit Z0. The output of the pulse shaper 1 is connected to the inputs of the information confidence block, the single vibrator 8 and the logic multiplication circuit 9. The output of the single vibrator B is connected another input of the logical multiplication circuit 9, the output of which is connected to the input of the key circuit 3. The device (fig 3) additionally contains a single vibrator 8, a pulse counter 10 and a coincidence circuit 11, which are connected between the pulse driver 1 and the key circuit 3 connected to the inputs of the synchronization unit 2 and the one-shot 8. The output circuit of the one-shot 8 is connected to the input of the counter of 10 pulses and one input of the O-match circuit. The output of the counter 10 is connected to another input of the coincidence circuit 11, the output circuit of which is connected to the input of the key circuit 3. The device (FIG. 1) works as follows. A voltage is applied to the input of the driver 1 from the terminals of the core of the DC electric machine (Fig. T in). It includes the variable component of cog Pulsations of back-EMF. Using the pulse generator 1, this signal is converted into rectangular-shaped pulses (FIG. T, c), after which it is fed to the inputs of the synchronization unit 2 and the key circuit 3. To determine the total pulses of the pulsation pulses, a full-wave rectified voltage is applied to another input of the synchronization unit. (Fig. 4a). Tooth pulsations of counter-emf are not synchronized with the frequency of the mains supply and are determined by the average value of the voltage on the engine bark and the moment of load on the shaft core, as well as the inductance of the core circuit (Fig. C). Information about the frequency of rotation of the core is contained and unambiguously determined by the duration of the pulses of serrated pulsations of counter-emf, which may be distorted or absent altogether during transient overloads of the electric machine. The necessary data on the angular velocity of the core in a given half-period of the supply voltage can be obtained only if there are at least three impulses of the tooth pulsations, and even the duration of the average pulse uniquely determines the frequency of rotation of the core at the current time point. synchronization on the falling edge of the first pulse from the imaging unit 1 in this half-period of the supply voltage generates an enabling signal, which is fed to the control input of the memory device or memory device 5, depending on the current situation. Those. if in the previous half-period reliable information was recorded in memory A by the key circuit 3 and the enable signal from synchronization unit 2, the next pulse of the pulsation pulse is stored in the memory 5. Data output at the display unit 7 corresponds to the pulse duration recorded in storage device. Information is updated only upon a command to the control input of the memory device k from the synchronization unit 2 after the leading edge of the next pulse is determined. If this does not happen in this half-period, the data on the frequency of rotation of the core recorded in the memory of the device 5 is considered invalid and is erased. In this case, the information on the pulse duration recorded previously in the memory 4 is stored at the input of the display unit 7 and is considered reliable before the appearance of new information. If the next pulse in this or the next half-period of the supply voltage turned out to be full and recorded in the memory 5, the old information from the memory device is also erased to the input of the display unit 7, the command from the synchronization unit 2 sends the new information to the enable input of the switch 6. Such and similar situations are common in the operation of direct current electric machines from valve transducers rubbing them into counter-emf and inductive load. In most cases, direct-current electric machines operate in the mode of intermittent currents, which facilitates the release of tooth pulsations during those moments. time when the valve converter is closed and the electric machine is operating in a generator mode. In addition, the kinetic energy of the flywheel masses on the shaft of the core does not allow for one or two half-periods of the supply voltage to significantly reduce the angular velocity of the core. FIG. 7 shows the dependences characterizing the principles of construction of the device, 1 Dependence m (Fig. 7) characterizes the relationship between the duration of tooth pulsations and the frequency of rotation of the core of the electric machine. It is described with an expression. where T is the current value of the pulse duration of the tooth pulsations at the output of the switch 6; K - coefficient proportional to angular velocity of the core. Such a relationship between the frequency of rotation of the core and the signal at the output of the device is inconvenient when studying in systems for measuring, controlling and stabilizing the frequency of rotation. Therefore, the display unit 7, in addition to information functions, the dependence of the form (1) leads to the expression --TO-I-O / V), where TQd is the pulse duration, COOT corresponding to the minimum frequency of rotation of the core n, K is the proportionality coefficient. A device whose structural diagram is shown in FIG. 2, and the operation diagram of the individual nodes in FIG. 5, functions as follows (in the description we stop only at the differences in the operation of the considered device modification from the main variant). The inclusion between the pulse shaper 1 and the key circuit 3 of an additional one-shot 8 and the logical multiplication circuit 9 allows simplifying the device, i.e. to exclude the function of the converter in the display unit 7 (Fig. 2) of the dependence (1) to the form (2) and assign these functions to the one-shot 8 and the logic multiplication circuit 9. This happens as follows: From the output of the imaging unit 1, the pulses (Fig 5 e) arrive at the inputs of the synchronization unit 2, the one-shot 8 and the logic multiplication circuit 9. For definiteness, we assume that the impulse of the cog ripple in this half period turned out to be full. The front of this and any other impulse is allowed to use a one-shot 8 at a time equal to the duration of pulses of the pulsation pulses TQ, corresponding to the minimum frequency of rotation k p p (Fig. 5 d). At the same time, a pulse of a pulsating pulse is sent to one input of the logical multiplication circuit 9, and a signal from the one-vibrator 8 output to the other input. As a result of these two signals, a logical dependence of the form (1 J leads to the expression (2) the reasoning is the same and the only difference is that further operations in the device are carried out with corrected cogging pulsations (Fig. 5h) .This approach to solving the set task allows, due to a slight increase in the frequency measurement period to implement a device on logical elements and eliminate conversion of dependency (1) to expression (2) by display unit 7 Fig. 3 shows a structural diagram of the next device modification. It further includes a one-shot 8, a pulse counter 10 and a matching circuit 11, which are included between the pulse shaper 1 and the key circuit 3. They are designed to reduce the error in measuring the angular velocity of the core introduced by the inductance of the core circuit when the electric machine is overloaded. For this, the period of change of the pulsation pulsation is used as an information unit (Fig. 6.). The device works as follows. The back edge of each pulse from the pulse generator 1 (fig b i) starts the one-shot 8 for the time required to switch the timer 10 pulses. At the same time, the output from the one-shot 8 (fig. 6k) is fed to one input of the matching circuit 11 and another information from the output of the counter 10. As a result of the summation of the signals, at the output of the coincidence circuit 11, we obtain pulses (Fig 6 E) corresponding to the measurement period of tooth pulsations. The mechanism for recording information and updating it remains the same as in the main device. The difference from the previous measuring devices is that the period of change of pulsation pulsations (Fig. 6 E) is used to measure the rotation frequency of the core, and the back edges of the pulses are used. tooth pulsations. The proposed devices can be used in systems of automatic adjustment and stabilization.

rotation frequency of the core of electric machines of direct current, as well as for compensation of non-linearity of the control system,

Claims (3)

1. A device for measuring the angular velocity of the core of an electrical machine. A constant current containing a pulse shaper connected to the electric machine's main circuit, the first storage device, iy, the indicator and the synchronization unit connected to the power supply circuit of the electric machine, so that, in order to increase speed and expand the field of application, The device has a key scheme, a second storage device and a switch, with the input of the key scheme connected to the output of the software, outputs of the key scheme to the information inputs of the first and second storage devices, their outputs through the switch to the indicator, the second input of the device and synchronization - to the output of shaper outputs blokasinhronizatsii - to the control inputs of the first and second storage devices and switch 2, the device according to 1,. For example, in order to increase the accuracy of the measurement, the device introduces a one-shot and a logic multiplication circuit, while the input of the single-vibrator and the first input of the logic multiplication circuit are connected to the high speed driver circuit, the second input of the logic multiplication circuit is connected to the output of the single-vibrator, and the output of the logic multiplication circuit is connected to the input of the key circuit 3. The device according to claim 1, characterized in that, in order to reduce the influence of the inductance of the core circuit, a one-shot, a pulse counter and a coincidence circuit are inserted into the device, while the input of the single-selector is connected to the output of the driver, the input of the pulse counter and the first circuit input the matches are connected to the output of the single-selector, the second input of the matching circuit is connected to the output of the pulse counter, and the output of the matching circuit is connected to the input of the key switch. Sources of information taken into account in the examination 1.Agaykin D.I. et al- Sensors of control and regulation of "Mo, 1% 5. with , 2. USSR author's certificate number 162227. class, G 01 P ZM8. 19b2. , 3.Patent UK № 1 46501, Cl, G 01 P 3/5, 97b (prototype). w I e m Sh 0fff,