SU1713038A1 - Device for control of dc engine without contacts - Google Patents

Abstract

The invention relates to electrical engineering, in particular to electric machines of direct current with contactless switching of sections of the core winding, vt can be used as actuation devices in various automation systems. The aim of the invention is to reduce power consumption and increase reliability. For this, in the device, the current-clamping unit is designed as a controlled generator of 8 series of pulses, the input of which is connected to the common point of the measuring resistor 11 and the power input of the bridge switch 1. The first inputs of the logical unit ZILI-NE 7 are connected to the outputs of logical elements EXCLUSIVE OR 5, their the second inputs are combined and connected to the output of a controlled generator of 8 series of pulses, and the combined third inputs are connected via an input switch to the output of the speed control unit 9 and the common bus of the power source ani Under non-stationary modes (start-up, the action of impulse loads), a cyclical, with the frequency of the controlled generator, disconnects the power source of the windings 2 of the contactless motor. 6 ill. Yr 14 ^ L ^ —bil ^ Wooo > & 00

Description

The invention relates to electrical engineering, in particular to electric machines of direct current with contactless switching of core winding sections, and can be used in various automation systems.

Known technical solutions have low energy characteristics and low reliability.

Thus, a controlled valve electric motor is known, which contains two master oscillators, a reverse unit (switch), a single-phase voltage converter, a phase splitter, logic elements EQUILIBRIUM or

INEQUALITY, power amplifier (inverter) and a synchronous motor powered by a voltage from a t-phase inverter with a constant frequency.

The disadvantages of this technical solution are poor starting characteristic due to the engine entering into synchronism, and therefore it is unacceptable to perform current limiting during engine starting and overloading, low energy characteristics, especially at low loads, and powering the winding in width-modulated voltage leads to additional losses in copper and in the transistors of the power amplifier; low reliability

A known stator winding control system of a brushless DC motor, which contains a multiphase (three phase) stator winding, a multipole rotor, a rotor position sensor, made by three Hall elements, the signals of which are formed into a train of pulses (voltages), the phase of which can be inverted depending on the polarity of the input control signal, the means of excitation of the stator-winding current, the value of which corresponds to the absolute value of the input control signal, and the node pack ION (comparator) providing yuschy reverse rotation of the motor in dependence on the polarity of the control voltage.

The power transistors of the power amplifier, which regulate the stator winding excitation current, are controlled by the power circuits of the amplifier, and since the output transistors of the amplifier operate in a linear mode, this leads to an increase in power consumption and a decrease in reliability.

A DC motor with a multi-phase winding and a switching unit, controlled from Hall sensors, which contains a four-radial stator winding, a rotor position sensor, made on two Hall elements, is known.

the signals of which are formed in two sequences of pulses supplied to the decoder, from the output of which four sequences of signals with a shift of 90 zl.grad. served on power transistors,

0 commuting stator winding.

The reversal of the direction of rotation is carried out by changing the polarity on the second combined inputs of two logical elements EXCLUSIVE

5 OR.

The disadvantages of this technical solution are: low utilization rate of the copper of the stator winding due to the power supply of each section for 1/4

0 period, which leads to an increase in weight and size parameters of the engine; large ripple of rotational speed due to 90 eh. switching intervals; no engine protection when

5 its start-up or overload, which leads to reduced reliability ..

The device closest to the one proposed by the technical essence contains a bridge circuit of an exciter on transistors of equal conductivity type, the outputs of which are connected to the stator winding sections; three sequences of signals from the rotor position sensor are supplied to the inputs of the EXCLUSIVE OR logic elements, the combined second inputs of which reversal the direction of rotation; a decoder, the inputs of which are connected to the outputs of logical elements EXCLUSIVE ORING, and the outputs with the transistors of the bridge driver (amplifier); a measuring resistor connected between the common input of the driver transistors and the common power supply bus; A voltage comparator, one of the inputs of which is connected to the measuring resistor, the other to the reference voltage, and the output is connected to the control input of the cross-limiting transistor.

0 The emitter-collective transitions of the current-limiting transistor are included in the power supply circuit of the first three transistors controlling the power switches of the anode bus of the exciter.

5 When the signal from the measuring resistor exceeds the level of the reference voltage, the comparator provides the cut-off mode of the current-limiting transistor, resulting in the flow of the excitation current through the stator winding

is terminated. When the signal from the measuring resistor is less than the level of the reference voltage, the kamparator sets the current-limiting transistor to saturation mode and the motor operates on a natural characteristic.

The disadvantages of this technical solution are high current consumption due to losses in the current-limiting transistor connected in series in the power supply circuit of the transistor stages of the exciter, as well as low reliability.

The purpose of the invention. is to reduce power consumption and increase reliability.

The use of this invention in automation systems is more economical from the point of view of power consumption by eliminating the current-limiting transistor from the power supply of the transistor cascades of the switch and more reliable by implementing motor control over the logic circuits, as well as using the series generator tick as a limiting node. pulses.

This goal is achieved by the fact that in a device for controlling a contactless DC motor, comprising a bridge switch on transistors of different types of conductivity with outputs for connection to the core winding of a contactless motor; the position sensor of the rotor of the contactless motor, the outputs of which are connected to the first inputs of two-input logic elements of the SWITCH HJJIH, the second inputs of which are connected to the output of the direction of rotation setter; a decoder, the outputs connected to the control inputs of the bridge switch, the power inputs of which are connected to a power source; a measuring resistor connected between one of the power inputs of the bridge switch and the common power supply bus; current limiting node. The specified current-limiting node is designed as a controlled pulse train generator, three ZILI-NOT logic elements and a rotational speed control node are introduced, the first inputs of ZILI-NO logic elements are connected to the outputs of logic elements EXCLUSIVE OR, the second inputs of ZILINE logic elements are combined and connected to the output controlled generator of a series of pulses, the input of which is connected to the common point of the measuring resistor and the above-mentioned power input of the bridge switch, and the combined third inputs of the logical x elements ZYLI-not through the newly introduced

The switch is connected to the output of the part rotation control unit and the common power supply bus.

Fig. 1 is a structural-functional diagram of a device for controlling a non-contact DC motor; Fig. 2 shows an example of the implementation of a three-phase bridge switch on transistors; Fig. 3 is a plot of the voltages at the outputs of the main functional units of the device in the absence of a current limit; Fig. 4 shows plots of voltages at the outputs of the main functional units of the device in the presence of a current limit; Fig.5 g time dependence of the starting current of the engine; FIG. 6b shows an example of the implementation of a controlled pulse train generator.

The device contains a bridge switch 1 on transistors with outputs for connection to the core winding 2 of motor 3; sensor 4 position of the rotor, the outputs of which are connected to the first inputs of two-input logic elements

5 EXCLUSIVE OR 5, the second connected inputs of which are connected to the output of the setter 6 of the direction of rotation, and the outputs are connected to the first inputs of three logical elements ZILI-NOT 7. The second

0, the combined inputs of the logic elements 7 are connected to the output of the current limiting node 8, made in the form of a controlled generator of a series of pulses, and the third combined inputs of the logic elements

5 ZILI-HE 7 are connected via a switch to the common output of the rotational speed control unit 9, made in the form of, for example, an electronic device with an O (low) or 1 (high) voltage level output; the decoder 10, the inputs of which are connected to the outputs of logical elements ZILI-NOT 7, and the outputs - to the inputs of the bridge switch 1. the first of the power inputs of which are connected to the first bus

5, the power supply is directly connected, and the second is connected to the second output of the power supply through the measuring resistor 11 and is directly connected to the input of the current-limiting node 8.

0Device for controlling a contactless DC motor, depending The bridges from the position of the switches functionally related to nodes b and 9 can operate in the following modes: 1)

5 with no current limit; 2) in the {current limit mode; 3) in the speed control mode.

The three-phase bridge switch circuit shown in FIG. 2 has control inputs Uyi ... Uy6 and power inputs 7171303 with respect to the anode and cathode power supply buses. The transistors of switch 1 perform the function of power switches. The diodes shunting the collector-emitter junction of power transistors are designed to protect them at the moment of locking from the effect of self-induced EMF arising in the core winding 2 of the motor 3. whose phases are connected to the corresponding outputs F1 ... F3 of the switch 1.10 Voltage plots the output of the main units of the device, depending on the angular position (Qt) of the poTopa engine in the absence of current limitation and control / speed, shown in Fig. 3, 15 correspond to the operation of a contactless motor on a natural characteristic and the operation of the device in the first mode. Fig. 3a shows the voltage plots at the outputs of the sensor 4 of the rotor position, filled, for example, on magnetically controlled elements. These stresses have the form of a meander with a duration of impulse, and the voltage in ISO is zl.grad. and shifted in phase one relative to the other by 120 zl.25 degrees. If there is a logical zero at the second combined inputs of the logical elements EXCLUSIVE OR 5, their output voltages, shown on 30 in Fig. 3b, repeat the voltage shown on 4g. 3a. In the first mode of operation of the device, the second and third combined inputs of the ZILI-NE 7 ICC elements are low (figv). Taking into account the FUNCTION, performed by them, x1vx2vx3 O), the voltage at the output of each of the specified logic elements 7 is 40 Self voltage inverted relative to the input one. The voltages depicted in FIG. 3 are input to decoder 10, and the voltages in FIG. 3. e weekend. It is characterized by a logical-45 function of the decoder 10, which can be performed, for example, using a binary-decryption decoder, three logical elements 2 OR-NOT and three logical elements 2 OR. At the same time, for example, 50 or the outputs of the 2ILI-NOT elements are formed in accordance with the FIG. 3d, and the voltages at the outputs of the 2IL elements are formed in accordance with the FIG. and voltage plots (fig. 3d, e) the open state of each of the transistors corresponds to an angle of 120 al. At the same time, transistors of the same conductivity type 88 are opened by a shift of the p6 phase at 120 electrical degrees. And transistors of different types of conductivity, connected in series, with a phase shift of 180 zl.grad. Such a relationship between the voltage at the output of the sensor and the position of the rotor and the voltage at the output of the decoder 10, and accordingly, the switch 1 allows for the torque of the engine 3 and is characteristic of the operation of non-contact motors. If there is a high level of rotation at the output of the setpoint adjuster 6 and the initial other conditions of the voltage, shown in Fig. 3b, d, e, e, are shifted by 180 zl.grad. (inverted), which causes a change in the direction of the engine torque. The voltage plots depicted in Fig. 3b are also valid for other modes of operation of the device. In the current limiting mode, the device operates when the motor is started or overloaded, when the voltage drop across the measuring resistor 11 exceeds the limit level. In this case, high level voltage pulses are generated at the output of the controlled Generator 8 (Fig. 4a). In this case, the voltage at the output of the elements ZILI-HE 7 (Fig. 4b) and at the outputs of the decoder W (Fig. 4c, d) were pinned for the switch 1 of the switch, when closed, the root winding 2 is disconnected from the power source, Figure 5 shows the time dependence of the current in the core winding 2 of the motor 3 when it starts up and there is a current limitation. When the output voltage is low, the generator of the main generator B of the root has a winding 2 connected to a power source through the top and open transistors of different arms of bridge switch 1 And from ep Tel'nykh resistor 11, the current in the winding increases exponentially in accordance with the expression, ...., x Un - Err. , 2PF + H) -i. . right now (and is the initial current of the winding when it is not connected to the power supply: Eur is the motor's emf of rotation, proportional to its rotational frequency; T1 is the time of rise of current in the motor winding, t (2Рф + К); resistance of one phase winding;

R is the sum of the resistances of the measuring resistor, the internal resistance of the power supply and the equivalent resistance of two open transistors.

When a high voltage level appears at the output of the controlled generator 8, the root winding 2 is disconnected from the power source, and under the action of self-induced EMF, the current in the winding, keeping its direction, closes through one of the upper and one of the lower diodes, the measuring resistor 11 and the source power supply with partial energy recovery. In this case, the current in the winding is reduced exponentially, described by the expression

one . - + BP O -1 ,, h /. ) ha L (2NfCR +) L (

where 1NH is the initial current in the motor winding when it is disconnected from the power source;

ai / o voltage drop across the diode in the forward direction;

Ry. is the sum of the resistances of the measuring resistor 11 and the internal resistance of the power supply;

T2 21f / (2If + RJ.) - constant decay time of the current in the motor winding.

An example of the implementation of a controlled generator of a series of pulses is shown in Fig.6. The generator is made on the basis of a single threshold comparator DA. Elements R5, C2 perform the function of external communication and are elements of the correction. The direct input of the comparator is connected to the resistor 12 of the connection indicated above. Elements R3 and C1 act as a filter. The inverting input of KOfwiapaTopa is connected to the midpoint of a voltage divider on resistors R1, R2, the voltage on which is stabilized by means of a zener diode VO1 and a resistor R4. In this case, the voltage drop across the resistor R2 is the reference voltage (Uor) of the generator, and the voltage drop across the measuring resistor by the drive voltage (UBX) of the generator, which determines the voltage at the direct input of the comparator. The controlled oscillator 8 is excited due to the presence of internal distributed RBH and Sv parameters of the IC, as well as the presence of feedback on the R5, C2 external elements at Usx Uor. In this case, the duration (d) of high-level voltage pulses of the generator output is determined from the expression

r - () R5 / R8n (4), to the frequency (f) of the generator - by the parameters of the elements H} B 12, R5, C2 and has a direct dependence on the input voltage of the generator.

Taking into account the above expressions for increasing and decreasing the current of the winding 2 of the motor 3 with increasing frequency and decreasing the duration of high voltage pulses at the output of the generator 8 when it is excited, the amplitude of the variable component of the current decreases, however, the losses in the switch transistors increase switching. The slope of the tangent to the current build-up curve is less than the slope of the tangent to the current decay curve, and with increasing EMF of rotation, the difference in slopes increases .5 For Limiting the motor current at a given level, filling

y r-f (5)

the impulses of the generator 8 gfy his excitation is chosen so that with Heb O

0, the current increment during time g was less in absolute value of the current increment during the pause time. In this case, the generator 8 is slave. melts in the mode of cyclic breakdown of generation, and the maintenance of a given level

5 current limiting as the engine accelerates occurs by increasing the time the generator is in the generation stall mode. Control unit 9 is designed to control the rotational speed at a different switch position, functionally related to control unit 9 as compared to that indicated in Fig. 1, by forming on the combined third inputs

5 ZILI-NOT logic elements of a high voltage level, during which, regardless of the voltage levels at other inputs, the voltages at the outputs of the ZILI-NE 7 elements are low and the transistors of the switch 1 are in the closed state. In this case, the winding 2 of the engine 3 is disconnected from the power source, which corresponds to the mode of stopping the engine 3.

Claims (1)

5 Formula of gain A device for controlling a contactless, direct current motor, containing a bridge switch on transistors of different types of conductivity with outputs for 0 connected to the core windings of a contactless motor, the position sensor of the roto is i pa of a contactless motor, the outputs of which are connected to the first inputs of two-input logic elements. EXCLUSIVE OR, the second inputs of which are connected to the output of the directional direction adjuster, a decoder, outputs connected to the control inputs of a bridge switch, power inputs of which are connected to a power source, a measuring resistor connected between one of the power inputs of the bridge switch and a common power supply bus, node current boundary. characterized in that, in order to reduce power consumption and increase reliability, the current-limiting node is designed as a controllable generator of a series of pulses and three ZILI-NOT logic elements and a rotational speed control unit are introduced, the first inputs of ZILI-logical elements are connected with the outputs of logical elements EXCLUSIVE IL and the second inputs of logical elements ZILI-NOT are combined and connected to the output of a controlled generator of a series of pulses, the input of which is connected to a common point of the measuring resistor and the above-mentioned power input of the bridge switch, and the combined third inputs of logical elements ZILI NOT through the newly introduced switch is connected to the output of the speed control unit and the common power supply bus.  / m  i i -SH f f 9uz, S Phi. at