SU1653123A2 - Frequency controlled asynchronous electric drive - Google Patents

Description

one

i (6l) 1290464

(21) 4705433/07

(22) 14 „06.89

(46) 05.30.91. Bup. Number 20

(71) Volga Association for the production of cars

(72) V.V., Kashkanov, P.T. Yakomaskin, P.A. Pavrin and A.V. Belkin

(53) 621, 313,333.07L - 9 (088.8)

(56) USSR Author's Certificate No. 1290464, cl. H 02 R 7/42, 1984.

(54) FREQUENCY-CONTROLLED ASYNCHRONOUS ELECTRIC DRIVE

(57) The invention relates to electrical engineering, namely to electric drives based on asynchronous short-circuited motors. The object of the additional invention is to improve the operational performance by reducing losses and increasing the power developed by the engine in transient conditions. This is achieved by introducing the transistor component 23 of the stator current, made with the minimum and maximum constant voltage reflection unit 24 with the comparison node 25 and the multiplication unit 26. The sensor 13 of the stator current longitudinal component is configured with the voltage vector modulator 27 , the determiner 28 of the module of the specified stator current, two linear amplifiers 29, 30, the amplifier 31 with adjustable limiting, three nodes 32-34 and the multiplication unit 35. At the same time, the power developed by the engine 1 is increased in transient conditions and its operation modes are formed according to the criterion of an unconditional impulse of energy losses with automatic transition to a conditional minimum of losses with current and voltage limitations, which is most effective, for example, in electric vehicles with limited energy onboard source. 1 il.

L

The invention relates to electrical engineering, in particular to electric drives based on asynchronous short-circuited motors.

The purpose of the invention is to improve

performance indicators by increasing the power developed by the motor in transient conditions and reducing losses.

The drawing shows a functional diagram of a frequency-controlled asynchronous electric drive.

The frequency-controlled electric drive contains an asynchronous motor 1 with a short-circuited rotor, to the stator windings of which the phase outputs of the adjustable current source 2 are connected, the sequencer 3 harmonic signals connected in series, and the coordinate converting unit 4, made with four digital-to-analogue converters 5-8, adders 9- 12 and the connected outputs to the control inputs

YU

Ladies of an adjustable current source 2, unit 13 of the longitudinal component of the stator current, connected with the output to the same control input of the coordinate conversion unit 4, frequency-frequency sensor 14 of rotational speed, mounted on the shaft of the induction motor 1, driver 15 of the frequency of pulse of rotational speed sensor 14 made with outputs for frequency shaping and frequency sign connected to the corresponding inputs of the frequency-voltage converter 16 and the corresponding inputs of the shaper of 3 harmonic signals, re speed generator 17 with comparison node 18 connected by inputs to the outputs of frequency response knob 19 and frequency converter 16 is voltage respectively, while the output of speed regulator 17 is connected to the combined inputs of the zero-body 20 and module 21 of the allocation module 21 whose output is connected to the input of the voltage converter 22 is the frequency, the output of which and the output of the zero-organ 20 are connected by the corresponding inputs of the shaper of 3 harmonic signals.

In the electric drive, the transducer component 23 of the stator current is made with a block 24 limiting the minimum and maximum values of the DC voltage, the input of which is connected to the power source of the regulated current source 2, the output is connected to the inverting input of the reference unit 25, the non-inverting input of which is intended to connect a single setting current limiting factor. The output of the comparison unit 25 is connected to the first input of the multiplication unit 26, the second input of which is connected to the output of the speed controller 17, and the output of the multiplication unit 26 forming the output of the generator 23 of the transverse stator current component is connected to the corresponding control input of the coordinate conversion unit 4.

The unit 13 of the longitudinal component of the stator current is made with the determinant 27 of the voltage vector module, the determinant 28 of the module of the given stator current, two single-quadrant non-inverting linear forces

15

20

25

16531234

29 and 30, an amplifier 31 with an adjustable level of limiting the minimum value of the output signal, three comparison nodes 32-34 and a multiplication unit 35. In this case, the inputs of the determiner 27 of the voltage vector module are designed to connect the pulse control signals with the power switches of the adjustable current source 2. The output of the detector 27 of the voltage vector module is connected to the non-inverting input of the first node 32 comparing the setting unit 13 of the longitudinal component of the stator current, the inverting input of which is intended for connecting the setpoint of the maximum value of the voltage vector module and the output is connected to the input of the first single non-inverting linear amplifier 29 The output of the determinator 28 of the set stator current module is connected to the non-inverting input of the second comparison node 33 of the setting unit 13 of the longitudinal component of the stator current, inverter ruyuschy input of which is intended for connecting the modulation setting the maximum value of the stator current, and an output connected to the noninverting input of the second odnokvadrantnogo linear amplifier 30. The non-inverting inputs of both odnokvadrantnyh linear amplifiers 29, 30 are connected to the inverting input of the third unit 34 comparing the set point 13 of the longitudinal component of the stator current. The non-inverting input of the comparison node 34 is designed to connect the optimal ratio of the longitudinal and transverse components of the stator current, and the output through the amplifier 31 with an adjustable level of limiting the minimum output signal is connected to the first input of the multiplication unit 35, the output of which forms the output of the longitudinal component setter 13 stator current is connected to one of the inputs of the determinator 28 of the module of the specified stator current, the other input 50 is combined with another input of the multiplier 35 of the setting device 1 3 is a longitudinal component of the stator current and is connected to the output of the module 21 allocation unit. Other amplifier input

55 31 with an adjustable level of limiting the minimum value of the output

 the signal is connected to the output of the shape of the body 15 pulse frequency

thirty

35

40

45

In the coordinate conversion unit, the sine and cosine codes received from the outputs of the 3 harmonic signal generator are supplied respectively to the combined digital inputs of the first 5 and third 7 digital-to-analog converters and to the combined digital inputs of the second 6 and fourth 8 digital-to-analog converters. In this case, the analog inputs of the first 5 and second 6 digital-to-analog converters are combined and form an input on the transverse component, and the combined analog inputs of the third 7 and fourth 8 digital-analog converters form a control input on the longitudinal component,

The regulated current source 2 can be made using three fully controlled key elements 36 connected to the outputs of the three current relay regulators 37.

Frequency-controlled asynchronous electric drive works as follows.

The setpoint value of the rotation speed of the asynchronous motor 1 with the short-closed rotor, coming from the output of the speed setting unit 19, is compared with the actual speed value using the comparison unit 18. The received error signal is fed to the input of the speed controller 17, the output signal of which determines the initial value of the specified value of the transverse stator current component in the rotating orthogonal coordinate system d, q, oriented by the axis d along the rotor coupling vector.

Using the module allocation module 21, the module determines the output signal of the speed controller 17, which, through the voltage-frequency converter 22, determines the rotational speed of the coordinate system d, q relative to the rotor. The sign of this velocity is determined by a null organ of 20 "

The pulse frequency fa at the output of the voltage converter 22 is a frequency equal to

/} with, c

| 5 where z is the number of pulses per

one turn of the shaft of the asynchronous motor 1;

S0.ts 314 rad / s - nominal circular

mains frequency The pulses from the sensor 14 using the frequency generator 15 pulse frequency multiplied by a number equal to the number of pairs of poles p of the induction motor 1. The pulse frequency ffj at the output of the imaging unit 15 is equal to

03

fCO P z 2%

 5 where CO is the frequency of rotation of the rotor, with the sign {, -. determined by

The rotation of the asynchronous motor i l 1.

The frequency f of the harmonic signals received from the outputs of the former of the harmonic signals 3 is equal to

f2: - ± fco ± fpDigital codes of harmonic signals are fed to the corresponding digital inputs of multiplying digital-to-analog converters 5-8. The analog reference inputs of the digital-to-analog converters 5 and 6, from the output of the setting device 23, receives a signal of a predetermined value of the transverse component 1.

stator current, and on

reference analog inputs of digital-to-analog converters 7 and 8 - a signal of a predetermined value of the longitudinal component of the stator from the output of the setter 13. Using digital-4 analogue converters 5-8, signals 1 glp ° B are transformed into signals of setting currents izrt B to a fixed coordinate system with , / 3 (at the outputs of adders 9 and 10), and then into the harmonic signals of the task “

cov in stator phases 1d, i „, i (on

the outputs of the adders 9, 11 and 12), which are fed to the control inputs of the relay regulators 37 of the controlled source. current.

The operation of the setting units 13 and 23, which form the predetermined values of the longitudinal and transverse components of the stator 1 current, is based on the fact that in the asynchronous electric drive it is possible to obtain the moments required by the speed control conditions while simultaneously fulfilling the additional optimization criterion. the criterion of the minimum loss, which is possible for the entire range of rotor speed. However, it is important for an electric drive during acceleration or deceleration to develop the maximum possible values of power and torque. These modes are achieved only at maximum values of stator current vector moduli / I6fmax or voltage (. Therefore, the optimality criterion in these cases should be either maximizing power under conditions of voltage limitation or maximizing torque under current limiting conditions. These limitations always exist in real electric drive systems and are caused both by the limiting possibilities of the elements of the power converter and by the energy source.

The expression for any of the specified optimized quantities using the equations of the generalized machine can be written as

L 0F (K),

(one)

where E is a physical quantity (electromagnetic moment, current or voltage modulus), for a fixed value of which it is necessary to find the extremum of the optimized quantity (loss, electromagnetic moment or power, respectively);

F (K) is a function defined by the equations of the steady state and dependent on the machine parameters, angular velocity and coupling coefficient K, which is the ratio of the components of the stator current vector in the rotating coordinate system d, q:

Ij / i

The optimal value of the coupling coefficient corresponding to the operation of the machine in the minimum loss mode

(K Kopt), in the mode of maximizing the moment (K K.) and in the mode of maximizing power (K KV) can be determined from the condition:

EA / EC

about

After that, by the calculated value of the coupling coefficient and by the third j JQ is 20

25 you can determine i and i in the bootable magnitude of the electromagnetic moment

Thus, with respect to the magnitude of the coupling coefficient K, the following modes of operation can be distinguished.

If the required magnitude of the electromagnetic moment M and the current value of the rotor speed are such that they are reached at | . |

thirty

35

40

45

50

55

Kk | u5l

5 vwJX

max

then electric motor

can work in the mode of minimal losses, i.e. K must be equal to

COPT

If M and n are such that they are reached only with max (usl and K 4kop, then the value of K should be selected from the range Kotrr-K v in the function of maintaining the voltage at the level (l), / | U5 | mai (.

If M and n are such that they are achieved only with | Ij unimex. iusl

| Ue | me H K / KOPT, then the value of K should be selected from the range. -Kj as a function of the current limit at the level | 1 (- | Ц | WaxIf M and n are such that they are reached only with / 151 (Ch | rki 1 and fusUaxH then the value of vl must be calculated from the equation for the electromagnetic torque of the electric motor with the indicated limitations:

M p -L.B- 1t Iz

L2 1 - i Kg s iaxAt this, according to dependence (1), the losses in the second and third modes for intermediate values of K, other than Kg or Ku, will be greater than the minimum values of t „e„ corresponding KK), but less than at,. or

1, “IV PSP1EShS. t SP 11J-T1 D -1 ъ.

. Therefore, such an electric drive implements the principle of forming an asynchronous motor operating mode according to the criterion of an unconditional minimum of energy losses with an automatic transition to a conditional minimum of losses with current and voltage limitations.

The described functions are implemented by the sensor 13. The voltage limiting channel is formed by the determinant 27 of the voltage vector module, the first comparison node 32 and the amplifier 29, and the current limiting channel is defined by the determiner 28 of the stator current modulus 33, the second comparison node 33 and the amplifier 30.

The output signal from the determiner 27 of the voltage vector module is compared in the perceptive node 32 against its maximum value and the difference signal is fed to the input of the first one-quadrant non-inverting linear amplifier 29. If the difference signal is negative, then the output signal of the amplifier 29 is zero, if the difference is the signal is positive, then the output signal of the amplifier 29 is different from zero and is fed to the inverting input of the third comparison node 34, resulting in a decrease in the signal at the output of the amplifier 31 with an adjustable emym level limit the minimum value of the input signal. If the input signal of amplifier 31 is greater than or equal to K or Copt, then it passes to the output without changing. If the output signal of amplifier 31 is less than K or Copt, then the output signal of this amplifier is equal to K or KOPTB, depending on the current value of the rotor speed. After multiplying the output signal of the amplifier 31 by the output signal of the module extraction unit 21 in the multiplication unit 35, a signal for setting the longitudinal component of the stator current is received, which is fed to the corresponding input of the coordinate conversion unit 4. The operation of the current limiting channels is similarly performed.

The transducer component 23 of the stator current provides for limiting the setting of the transverse component of the stator current when the voltage of the power source of the regulated current source 2 in the motor mode is lower than the allowable value or when the voltage in the braking mode is higher than the allowable value (a typical example of such a source is accumulator torn battery i

The operation of the setting device 23 is carried out as follows. If the voltage Uj of the power source of the regulated current source 2 is within rn.n Ud c Udmox TO, the output signal of block 24 is zero, therefore the first input of the multiplication unit 26 from the output of the comparison node 25 receives a single setpoint signal and, therefore, the output signal multiplier block 26, which is the output of setpoint 23, is equal to the output signal

speed controller 17, i.e. in this case, the limitation of the transverse component setting of the stator current does not occur. If, however, the voltage Uj of the power source of the regulated current source 2 is within Uj with Uj U, then the output of block 24 is different

from zero, and entering the inverting input of the comparison node 25, reduces the signal of a single setpoint, as a result, after multiplying the output signal of the comparison node 25 in block 26

multiplying by the output of the speed controller 17 receives the if signal. tasks of the transverse component of the stator current, which is less than the output value of the speed controller 17,

Q thus ensuring the maintenance

the voltage Uj at the level Uj in the motor mode and at the level Uj mQ in the generator mode of the asynchronous motor 1,

5 Thus, the proposed frequency-controlled asynchronous electric drive in comparison with the known one has the best performance indicators, which consist in a significant increase in the power developed by the machine in transient conditions and ensuring the formation of the operating modes of the asynchronous motor according to the criterion of an unconditional minimum of energy losses with automatic transition to the conditional minimum losses at current and voltage limitations. The most effective is the use of this electric drive as part of an electric vehicle or any other vehicle with a limited amount of energy from an onboard source.

five

0

Claims (1)

Invention Formula Frequency-controlled asynchronous electric drive on av.ev. No. 1290464, characterized in that, in order to improve operational performance by reducing losses and increasing the developed power in transient modes, a transverse component generator of the stator current with three inputs is introduced, the first input connected to the input of the DC power source | current source, and the second input and output connected between the output of the speed regulator and the combined analog inputs of the first and second digital to analog converters and composed of a unit for limiting the minimum and maximum values of the constant voltage, the input of which is the first input of the transverse component setter the stator, the comparison node and the multiplication unit, the output of the said limiting block is connected to the inverting input of the comparison node, the non-inverting input of which is intended supplying the single setpoint of the current limit factor, and the output is connected to the first input of the multiplication unit, the second input of which forms the second input of the transverse stator component generator of the stator, and the stator longitudinal component generator of the stator current modulator, the modulator of the given stator current, two single-ended non-inverting linear amplifiers with an amplifier with an adjustable level of limiting the minimum value of the output signal, three nodes of comparison and a block intelligently At the same time, the inputs of the voltage vector modulus detector are intended to connect the pulse control signals with power switches of a regulated current source, the voltage vector voltage modulus detector output is connected to the non-inverting input of the first comparator unit of the stator longitudinal component of the stator, the inverting input of which is intended for connecting the setpoint maximum value of vector modulus five 0 five 0 five 0 neither, and the output is connected to the input of the first one-quadrant. non-inverting linear amplifier, the output of the determinant of the module of the given stator current is connected to the non-inverting input of the second comparison node of the sensor of the longitudinal component of the stator, the inverting input of which is intended to connect the setpoint of the maximum value of the stator current modulus, and the output is connected to the input of the second single-quadrant non-inverting linear amplifier, output of the stator current one-quadrant non-inverting linear amplifiers are connected to the inverting inputs of the third reference node of the driver n the stator current odolite component, the non-inverting input of the said comparison node is designed to connect the optimum ratio of the longitudinal and transverse components of the stator current, and the output through an amplifier with an adjustable level of limiting the minimum output signal is connected to the first input of the multiplication unit, the output of which sets the output of the setpoint generator the longitudinal component of the stator current is connected to one of the inputs of the determinant of the module of a given stator current, the other input of which is combined with another input by the multiplier unit of the setting unit of the stator current longitudinal component and connected to the output of the extraction module of the module, and another input of the amplifier with an adjustable level of limiting the minimum output signal value is connected to the output of the frequency pulse generator.