SU1259428A1 - Rectifier electric motor - Google Patents

Abstract

The invention relates to valve motors (BD) and can be used in electric drive systems of various industrial mechanisms when powered from a source of comparable power. The purpose of the invention is to reduce the ripple of the engine torque and the distortion of the supply voltage. VD with a DC link contains a synchronous machine 1c with independent excitation connected to mains 2 via two parallel-connected rectifier-inverter units with an individual CHEVBM UNG &

Description

c) water reactors 3, 4. Each unit contains, respectively, the first and second rectifiers 5, 8, the first and second inverters 6, 9, the first and second smoothing throttles 7, 10. The first and second rectifiers are controlled from independent control systems with contour. speed control containing a speed sensor 11 on the motor shaft, speed controller 12, and a current control loop containing current regulators 13, 14 of the first and second rectifiers, the first inputs of which are connected to the output of the speed controller, and the second inputs respectively with sensor outputs 15, 16. Outputs

controllers 13, 14 are connected to the outputs of the systems 17, 18 by pulsed-phase control of rectifiers. The inverters are controlled from the first and second systems 19, 20 of the pulse-phase control of the inverters. VD is additionally equipped with an electromagnetic torque extraction unit 23 connected by the first and second inputs

The invention relates to electrical engineering, in particular, to high-power valve motors, powered by frequency converters with a DC link, and can be used in electric drive systems of various industrial mechanisms when powered from a source of comparable power.

The purpose of the invention is to reduce ... the motor torque pulsations and reduce the power distortion of the voltage.

Fig. 1 shows a block diagram of the valve motor j in Fig. 2, a diagram of a block of thunder moment; Fig. 3 is a block diagram of the determination of the amplitude of the moment variation; in Fig. 4, linear diagrams of the formation of the moment; Fig. 5 is the sensor circuit of the components of the Current; Fig. 6 is a functional block diagram of the formation of advance angles; Fig. 7 is a vector diagram.

sensors 24, 25 instantaneous voltages of inverters, a third input to the output of the sensor 11, a fourth input to the output of the total stator current sensor of the synchronous machine, fifth and sixth to the outputs of sensors 15, 16. The output of unit 23 is connected to the input of the unit 26 isolating the amplitude of the oscillations of the electromagnetic moment, the output of which is connected to the input of the non-linearity unit 27 to the criticality, the output of which is connected to one of the system 19 inputs. The first output of the motor full current sensor 28 is connected to the input of the static current sensor 29, sec This input is with the input of the sensor 30 of the motor dynamic current, and the third with one of the inputs of the block 23. The input of the inverter control angle forming unit 31 is connected to the output of the sensor 29, and the two outputs - with the inputs of systems 19, 20 engine power can be approximately doubled without any additional devices. 7 or „

The DC motor with DC link consists of a synchronous machine 1 with independent excitation connected to the power supply

networks 2 through two parallel-connected rectifier-inverter units with individual input reactors 3 and 4. The first rectifier-inverter unit contains the first

rectifier 5, first inverter 6, super smoothing choke 7. Second rectifying inverter unit contains the second rectifier 8 second inverter 9 and the second smoothing choke 10.

The first and third rectifiers are controlled from independent control systems with subordinate current and speed circuits. The speed control loop includes a speed sensor 11 on the motor shaft and a speed controller 12. The specified speed corresponds to the voltage from an independent source, the incoming

to the second input of the speed controller. .

In the current control loop, input regulators 13 and 14 of the current of the first and second starters, the first inputs of which are connected to the output of the speed regulator, and the second inputs respectively of the outputs of sensors 15 and 16 of the second and first rectifier outputs of the regulators 13 and 14 currents are connected to the outputs of the systems 17 and 18 pulsed phase-controlled rectifier.

The inverters are controlled from the first 19 and second 20 systems of pulse-phase inverter control. The pulse-phase control systems are synchronized by the stator voltage using the inverter synchronization unit 21, the rotor position sensor 22. Synchronization is carried out in a known manner: at low speed — using a position sensor, and at a speed sufficient for natural commutation, voltage at the terminals of the synchronous machine.

In the valve motor with a DC link, the unit 23 for extracting the electromagnetic moment of the valve motor, connected to the first | & and the second inputs to the sensors 24 and 25 instantaneous voltage values of the inverters, the third input to the output of the speed sensor 11, the fourth input to the output of the total stator current sensor output of the synchronous motor, the fifth and sixth to the outputs of blocks 1 and 16. The output of block 23 connected to the input of the unit. 26 isolating the amplitude of oscillations of the electromagnetic moment, the output of which is connected to the input of the non-linearity byyok 27 with the deadband, the output of which is connected to one of the inputs of the system 19. The first output of the full-current sensor 28 is connected to the input of the static current sensor 29, the second output - to the sensor input 30 of the dynamic current of the engine, and the third with one of the inputs of the electromagnetic torque extraction unit 23.

The input of the inverter control angle forming unit 31 is connected to the output of the static sensor 29 then; ka, and the two outputs to the inputs of systems 19 and 20 of the inverter control.

5 th

15 0 5

0

five

The signals from the inputs from sensors 24 and 25, voltage, as well as blocks 15 and 16 are sent to multiplying blocks 32 and 33, vertical e fi, Ie on analog multiplying circuits. The outputs of these multipliers are a signal proportional to the corresponding value of the electromagnetic power supplied to the first and second inverters that feed the motor. The signal from the motor full stator current sensor from the input c1 of attor 34 is fed to a quad 35, which is used to determine the total active power loss in the stator of the motor. The quad gain is taken to take into account losses in the three phases, as well as losses in the steel of the engine. The sum of the currents 1c and 1c, is not supplied to the input of the quadr 35, since the total stator current of the motor is formed as a geometric, and not arithmetic, sum made up 110% of the output currents of the first and second inverters.

The outputs of the blocks 32, 33 and 35 are fed to the adder 34 and further to the dividing block 36. The second input of the dividing block is the signal CL) from the engine speed sensor. Ta- By the CMM, at the output of unit 23, the dependence of the electromagnetic moment developed by the synchronous machine 1 is obtained.

Line diagrams, which explain the process of forming the electromagnetic moment of a motor M for

f-f-p

cases of equality of the values of the rectified currents of the first and second inverters, are presented in figure 4. The diagrams also indicate the angle of control of the inverters p, the average value of the electromagnetic moment M

si.

the oscillation amplitude of the electromagnetic moment, the stator motor phase block, the switching angle of the inverter gates.

E

Blocks 24 and 25 are instantaneous voltage sensors, such as rheostat sensors. Lime technical means can be carried out and galvanic isolation of them from block 23, if such a need arises.

The amplitude block of the oscillations of the electromagnetic moment consists of a filter that extracts the average value of the electromagnetic moment Mp, an adder, on which the difference between the current elec- tric component is determined, is implemented using a capacitor 45, a resistor 46 and an amplifier 47. The output of the dynamic current sensor 30 is connected with the third entrance

J current regulator first mitel. The outputs of the amplifiers 48 and 49 are outputs of a static sensor and a full current sensor, respectively. Static current sensor output through

jq, the inverter leading angle forming unit 31 is connected to the inputs of the systems 19 and 20 of the pulse-phase control.

Unit 31 (Fig.6) includes summagnetomagnetic moment M and its average value.

the filter of block 26 contains a passive RG or LC filter 37 with an output amplifier providing the resulting transfer ratio 1} O, and an adder 38. The output of block 26 (the input of adder 38) is connected to block 27, which is non-linear with the dead zone . This non-linearity is typical.

Deadband size

block 27 is chosen to be equal to admissible 50 and 51, scale blocks 52 and 53, to the second value of the amplitude of oscillations, elec- tronic non-linear blocks 54 and 55, scale

Specified

20

25

of the magnetic moment. This value cannot be equal to zero, since in the scheme of a valve electric motor with a DC link, it is impossible in principle to obtain an electromagnetic 4 moment without pulsations with a finite number of phases of the motor stator. The maximum of the pulsations of the electromagnetic moment and, therefore, insensitivity should be less than the maximum of the pulsations of the torque of the valve motor with a six-phase inverter and several values that are characteristic of a twelve-phase inverter (approximately 1.8-2.3 times less than the pulsations with six-phase inverter).

The motor full current sensor is a known current meter circuit (FIG. 5). The stator current of the motor is controlled by current transformers 39 connected in a star. The windings of the transformers are loaded on the exporter 40 with the output resistor 41 and the capacitor 42. The meter load is the resistors 43 and 44, the capacitor 45 and the torus ™ 46. The resistances of the capacitor and resistors are such that the load current is small compared to the rectifying current of the rectifier 40. A signal proportional to the total current of the motor is removed from the resistor 43, the signal is further amplified and generated by an amplifier. From resistor 44: a signal is removed that is proportional to the static component of the full current.

The static current sensor is implemented by a resistor 44 and an amplifier. A signal proportional to the dynamic component of the total current is removed from resistor 46. Dynamic sensor

40

block 56, adder 57, nonlinear block 58. Using blocks 54, 55 and 58, the dependence is realized

  arccos (1 - ---),

where 1 is the static current value

engine; 1 - the super-transition amplitude

the current component of the two-phase short-circuit of the synchronous motor in nominal mode; J3 is the control advance angle equal to the commutation angle of the inverters or rectified current of the inertors 1

I j (this is the minimum value

2

control angle at which the valve motor operation is possible).

Scale Gain

block 52 is equal to K ---. Similarly

using blocks 5, the dependency

I

53 and 55 are implemented45

and arccos 2

()

V 9Т ° К

The K'9FF gain of block 53 is equal to

one ."".

The angle p is numerically equal to the angle of commutation of one separately taken inverter if its current load is equal to half the total. It's obvious that

The condition ensuring the normal use of an electric motor is that the power factor of the engine remains approximately constant. Under the conditions of equality Id,

the component is implemented using a capacitor 45, a resistor 46 and an amplifier 47. The output of the dynamic current sensor 30 is connected to the third input

current regulator first mitel. The outputs of the amplifiers 48 and 49 are outputs of a static sensor and a full current sensor, respectively. Static current sensor output through

an inverter leading angle forming unit 31 is connected to the inputs of systems 19 and 20 of pulse-phase control.

Block 31 (Fig.6) includes adders 50 and 51, scale blocks 52 and 53, nonlinear blocks 54 and 55, scale

0

five

block 56, adder 57, nonlinear block 58. Using blocks 54, 55 and 58, the dependence is realized

  arccos (1 - ---),

where 1 is the static current value

engine; 1 - the super-transition amplitude

the current component of the two-phase short-circuit of the synchronous motor in nominal mode; J3 is the control advance angle equal to the commutation angle of the inverters or rectified current of the inertors 1

I j (this is the minimum value

2

control angle at which the valve motor operation is possible).

Scale Gain

block 52 is equal to K ---. Similarly

I

using blocks 5, the dependency

53 and 55 implementations

and arccos 2

()

V 9Т ° К

The K'9FF gain of block 53 is equal to

one ."".

The angle p is numerically equal to the angle of commutation of one separately taken inverter if its current load is equal to half the total. It's obvious that

The condition ensuring the normal use of an electric motor is that the power factor of the engine remains approximately constant. Under the conditions of equality Id,

 should be fair

constitution

 D. + Ij COS, X COS jg

or

COS + COS 2 2 COS

in accordance with FIG. 6 and the equality given, the implementation of the dependency is obvious, arccos (2 cos and - - using blocks 56-58,

Coemer amplification block 56 is equal to two.

Fig. 7 is a vector diagram illustrating two possible modes of a valve motor. In the first control mode of the first and 8th invertors, the control lead angles are equal to each other, i.e.. In the second case, the first inverter has an angle of control, and the second. In this case, JB, 2, the condition that ensures the invariance (remaining) of the power factor of the engine during variations p and v depends on the current of the engine.

Block 31 is implemented using standard hardware, including non-linearities that realize trigonometric dependence.

The device works as follows.

I In static mode with a small static moment signals from the outputs of blocks 27 and 30 are missing. Equal in magnitude signals arrive at the inputs of current regulators 13 and 14, with the result that the rectified currents of the rectifiers 5 and 8 are equal to each other (regulators of the valve motor current as 1 PI F regulators). At the same time, the angles of the control of mirrors are different from each other, so KZtK i j8, j. Thus, the first driver has a steering angle.,. The steering angle and p for the purpose of increasing the stability of the inversion are taken with some margin relative to the calculated ones. The above angles are in the same cases, which are characteristic of ventilated engine motors with a single inverter. .

With increasing load on the shaft

the motor current increases 1 (|. "Ijj + IJ, while changing the values of the control advance angle,, tPi, the angle of co-oscillation Y, Y.

one

1259428. ,:

The process of forming the torque curves of the valve motor is

put on figs, a. Curves М „(1) and М, (€), 1

determine the proportion

1 - h "g

electromagnetic moment of the engine

developed from current inverters. In this case, the processes of formation of the electromagnetic matter can be considered independently of each other for one and second inverters. Since the rectified current Ij is only half of the total Jj d d f Eg and Y are small. So in the usual schemes of valve electro

 ,

mr

 BUT

given

device

 -I-.

M value

.. - ..

due to the independent operation of inverters close to 0.5 M, j.p. The limit value of the amplitude of the variable component of the moment

  g 0,5-К ,, sin - | -,

where K, is the proportionality coefficient, which depends only on the engine design characteristics. For the first inverter, we have.

DM /, - 0,5 R, sinp ,.

If the control steering angles are the same and equal, the amplitude of the variable component of the electromagnetic moment is approximately equal to

Q j

five

lm

mr

31

 ; with K sin- | -. The values of J5j and ppm a -5 2,

move within limits

at

d -1- Pr A

on: H ft - -1.6 G 3 Therefore, the analyzed values are equal, respectively, H,. O, 707 K, lm, 0.25 K, lm, 0.433 K ,.

As can be seen from the linear diagrams, the phase positions of the nonlinear distortions of the electromagnetic moment curve do not coincide. Therefore, as calculated, large values should be taken for one and second cases, LM, K, 0.707, AM, 0.433.

Thus, the decrease in the amplitude of the variable component of the moment is approximately doubled,

The real decrease in the specified parameter due to the influence of the switching process is even more significant.

s

The resulting curves of the electromagnetic momentum M, and the motor current Ija are also presented in figure 4. The analysis of the curves shows that, along with a decrease in the amplitude of the variable j, which is a component of the moment, its frequency of pulsations approximately doubles. At the same time, the current curve of the stator phase of the engine is improved - the harmonic content of the current decreases, and therefore the efficiency of the engine increases.

With an increase in the static moment on the shaft, the calculated values of the angles pj increase. and E, and, consequently, pp decreases gradually, approaching Eg. Therefore, the efficiency of the described process of reducing the variable component of the current amperes, the harmonics of the 5th and 7th order disappear. The specified value of the difference occurs when the values of the angles of advance control of the inverters

,, - -

f. -b

the efficiency of improving the quality indicators of the current consumed from the network decreases somewhat with a decrease in the rotational speed of the valve engine, i.e. with an increase in the absolute values of the control angles ot and ot,

In dynamic modes, for example, when the motor torque is increased from the dynamic current sensor, the signal is applied to increase the current controller setting of the first rectifier (higher straps with a large control angle), the electromagnetic torque rises to 20 The second rectifier is loaded only decreases steadily, in order to prevent the preventive component of rectifier 15

To prevent this phenomenon, an additional signal from the nonlinear unit 27 is introduced into the pulse-phase control circuit 19 of the first inverter. At 25 this angle D is additionally increased to its limit value of approximately TG / 3. The process of improving the electromagnetic torque curve of the engine is of the nature described earlier with the only difference being that the power factor of the engine decreases slightly (as a result of increasing values of j3, and, j). The consequence of this is an increase in the total current Ij. However, in the area of nominal engine loads, this phenomenon does not reduce the positive properties of the device, implying an improvement in the electromechanical characteristics of the engine. A further increase in la does not occur (higher than

35

it is current, which provides increased stability of the inversion of the first and second inverters. The adjustment process takes place in this order; a signal appears at the output of sensor 30, the setting of pe- is increased. the horn 13 decreases as a result; The rectifier control angle, the Z through the rectifier 3 and the inverter increase. 6. Current

 through inverter 9 remains unchanged.

With a negative signal from the output of sensor 30, the reverse process of reducing the load of the first inverter is observed.

With an increase in the driving voltage, the input signal at the input of the regulators t3 and 14 increases, the control angles of the rectifiers 5 and 8 decrease, and the total current of the motor increases. Almost simultaneously, the input signal of the regulator 13 begins to increase due to the additional signal from the sensor 30. Inverter 6 will take even more load, and inverter 9 gradually begins to unload to a static current.

40

T v

Because of the presence in the systems and 20 restrictions on the angle ahead

E.

nineteen

Nor is the control (the angle limiting unit in the pulse-phase control systems is typical).

The valve motor operates at different angles of control of the first and second rectifiers. This leads to full or partial mutual compensation of individual higher harmonic currents generated by the converter in the network. So, for example, if the difference of the control angles of the rectifiers DY ot, -ot is close to F / 6, then from the network curve

current harmonics of the 5th and 7th order disappear. The specified value of the difference occurs when the values of the angles of advance control of the inverters

,, - -

f. -b

effective25

35

45

it is current, which provides increased stability of the inversion of the first and second inverters. The adjustment process takes place in this order; a signal appears at the output of sensor 30, the setting of pe- is increased. the horn 13 decreases as a result; .. The angle of control of the rectifier, the Zo-z through the rectifier 3 and the inverter increases.

 through inverter 9 remains unchanged

With a negative signal from the output of sensor 30, the reverse process of reducing the load of the first inverter is observed.

With an increase in the driving voltage, the input signal at the input of the regulators t3 and 14 increases, the control angles of the rectifiers 5 and 8 decrease, and the total current of the motor increases. Almost simultaneously, the input signal of the regulator 13 begins to increase due to the additional signal from the sensor 30. Inverter 6 will take even more load, and inverter 9 gradually begins to unload to a static current.

The adjustment process with a decrease in the voltage of the task takes place in the specified order.

In this way, the operation of a valve motor ensures the minimization of the variable component of the electromagnetic moment, as well as the improvement of the quality of electric power at the input of the valve transducers.

Reduction of the variable component of the electromagnetic torque of the engine

40

50

n

about half excludes its vibration, the vibration of its individual parts, and especially its current-carrying ones. The motor becomes less sensitive when operated at speeds where its resonant frequencies appear. Due to the mode of operation of the inverters, which is close to 12-phase, the shape of its current curve is significantly improved. The efficiency of the engine increases by approximately 0.2-0.3% due to a decrease in the proportion of harmonics and losses from them. Different values of the control angles of the rectifiers lead to the fact that the amplitude of the switching distortions s of the mains voltage curve decreases approximately by half, as the commutators of the rectifier valve are realized independently of each other, i.e. to 12-phase. Under these conditions, the use of the proposed device leads to an improvement in the quality of the voltage. If the power of the network is limited, then with the same planned power rates (the supply voltage using the proposed device, the engine power j can be approximately doubled without the use of additional devices.

Claims (1)

Invention Formula A valve electric motor containing a synchronous machine with independent excitation, two parallel-connected alternator-inverter units, which form a frequency converter with a DC link, pulse-phase control systems of the first and second rectifiers, the first and second inverters, the regulator the tori current tori, the first and second current sender sensors, the outputs of which are connected to the j second inputs of the current regulators of the first and second torques, respectively, the speed controller motor L connected to the first inputs re59428 12 current drivers, rectifiers, speed sensor associated with the input of the motor speed regulator, rotor position sensor, inverter synchronization unit, connected with the stator windings of the engine and the rotor position sensor, and outputs with the first the inputs of the pulse-phase control systems first 0 and the second inverters, that is, with the fact that, in order to reduce the ripple of the rotational moment and distort the supply voltage, it is equipped with instantaneous value sensors 5 voltages of the first and second inverters, sensors of the static and dynamic currents of the engine, a block for extracting the electromagnetic moment of the motor, a block for extracting the amplitude 0 variable component of the electromagnetic moment, nonlinearity unit with dead band, block for the formation of inverter advance angles, the instantaneous voltage sensors of the first and second inverters are connected to the first and second inputs of the electromagnetic discharge unit, respectively, of the rectifier current sensors connected , 0 with the fifth and sixth of its inputs, outputs. engine current sensors - with its fourth input, the speed sensor output is connected to the third input of the electromagnetic torque extraction unit , engine, the output of which is through successively connected selection unit. the amplitude of the variable component of the electromagnetic moment and the nonlinearity unit with the insensitive zone is connected to the second input of the pulsator – basic control system by the first inverter, the output of the static current sensor of the engine is connected to the input of the forward angle unit j inverters, the outputs of which are connected to the second inputs of the pulse-phase control systems of the inverters, the output of the motor dynamic current sensor is connected to the third input of the current regulator of the first rectifier. 23 2g - - -f-1 (J / r f I g /./ T.M  y () 2G ff. 7. / f С t 4i4 M4x4Hx4tix | 4  2 ft)  ill / y / r (t) 7. / t  From 4 0 Sh Fiel  four: / g. ig. b PeAaKtop A.iffiimicHHa Compiled by A.Santalov Tehred L. Serdaokova Proofreader M. Maksimishinets, Order 5135/55 Circulation 631 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 FIG. 7