SU1488950A2 - Ac drive - Google Patents

Description

The invention relates to electrical engineering and can be used in the mining industry. The purpose of the invention is to simplify the design and increase reliability. To this end, in the AC drive, the EMF compensation unit 14, which is part of the regulated current source 2 in the rotor circuit of the induction motor 1, consists of a scale amplifier connected in series,

1488950 A2

X

3

1488950

four

an inertial link and a coordinate converter with reference inputs for connecting to the outputs of the 4 harmonic signal shaper and an output $ forming the output of block 14 for connecting to one of the inputs of the pulse-phase control system 12 of a controlled source 2. The input of the scale amplifier is an input of block 14, connected to the output of the slip frequency controller 5 connected between the output of the phase discriminator 6 and the input of the former 4, the outputs of the former 4. are connected to, 5 inputs of the coordinate transducer 3, the output of the li ne to three-phase input controlled source 2. At one input of the phase discriminator '

6, the active and reactive rotor current command signals are received at the output of the shaper 7 of these signals, and the other inputs are signals of actual values of the rotor active and reactive currents generated by the block 8 inverse coordinate transformation by signals of current sensors 9 and voltage sensors 10 set in asynchronous motor stator circuits. The correspondence of different currents to the reference signals is ensured by using the EMF compensation signals of the block 14, which by the output signals of the driver 4 and the slip frequency controller 5 are fed to the corresponding inputs of the block 14. 2 Il.

The invention relates to electrical engineering, in particular to an AC electric drive 25 based on a dual-power machine with a direct frequency converter in the rotor circuit, can be used in mechanisms requiring high dynamic properties and increased reliability, for example, in the mining and metallurgical industry when adjusting the rotor speed relative to the synchronous speed of the feed field, and is an improvement 35

main drive

auth. No. 1037405.

The purpose of the invention is to simplify the design and increase reliability.

Figure 1 shows the functional diagram of the AC drive; Fig, 2 - diagram of the execution unit EMF.

The AC drive contains an asynchronous motor 1 (FIG. 1) with a phase rotor, an adjustable current source 2, a converter of 3 coordinates, a shaper of 4 harmonic signals, a slip frequency controller 5, a phase discriminator 6, a shaper of 7 signals for setting active and reactive rotor currents, a block 8 inverse transform with sensors 9 and 10 of the current and voltage of the stator at the input.

The composition of the regulated current source 2 includes a three-phase regulator

11 current system 12 pulse-phase control, direct frequency converter 13, block 14 compensation of EMF.

The stator of the motor 1 is connected to the mains, and the rotor is connected to the output of the regulated current source 2, the three-phase input of which is connected to the output of the converter of the 3 coordinates. The first and second outputs of the shaper 4 harmonic signals are connected to the first and second inputs of the converter 3 coordinates, the third and fourth inputs of which are connected respectively to the first and second outputs of the shaper 7 of the rotor active and reactive current reference signals, the first output of which is also connected to the first input of the phase discriminator 6. The second and third inputs of the phase discriminator 6 are connected respectively to the first and second outputs of the inverse transform unit 8, the inputs of which are connected to the outputs of the dates 9, 10 stator current and voltage. The output of the phase discriminator 6 is connected to the input of the regulator 5 of the slip frequency. The output of the latter is connected to the input of the shaper 4 harmonic signals and to the feedback input on the slip frequency of the shaper 7 55 active and reactive rotor current reference signals connected to the feedback input on the stator reactive current and to the third output of the inverse transform unit 8.

five

1488950

6

The outputs of the three-phase current regulator 1 1 and the EMF compensation unit 14 are connected respectively to the first and second inputs of the system 12 pulse-phase control connected by the output to the input of the direct frequency converter 13. The output of the latter forms the output of the regulated current source 2. ten

The EMF compensation unit 14 is made of a series-connected scale amplifier 15 (FIG. 2), an inertial link 16 and a coordinate converter 17, the reference inputs of which 15 are connected to the corresponding outputs of the shaper 4 of harmonic signals. The input of the scale amplifier 15 is connected to the output of the slip-frequency controller 5, and the output 20 of the converter of the 17 coordinates forms the output of the EMF compensation unit 14.

The AC drive works as follows. 25

After starting and accelerating the motor 1 by one of the known methods used for dual power machines, up to the speed at which the slip frequency of the engine enters the output operating frequency range of the direct frequency converter 13, an adjustable current source 2 is connected to the rotor, and the electric drive is translated from unregulated to regulated operation.

The rotor windings are controlled by the control system. Three phase to

the current controller 11 ensures that the rotor phase currents correspond to the reference signals due to the large gain in the rotor phase current loop. Signals from the reference chas- 45 totoy slip and phase shift of 120 el.grad, coming from the output of inverter 3 coordinates, the inputs of which are supplied reference signals harmonic with an output of 4 and signals z'adaniya ίο.- reactive and active ϊ _α "", The components of the rotor current from the outputs of block 7. The frequency of the signals at the output of shaper 4 is proportional to the magnitude of the analog signal from the output of the regulator 5 slip frequency ..

The same signal is used as a feedback signal for the rotor speed and is fed to the feedback input of unit 7. The output Δφ of unit 6 is proportional to the angle of mismatch between the rotor current vector and its setting. The formation of this signal in block 6 is carried out by comparing the reference signal and the actual value of the rotor current.

The correspondence of the Phase currents to the reference signals is ensured, in particular, by using the EMF compensation signals generated by the compensation block 14. The formation of compensation signals is carried out in the electric drive by using the output signals of the driver 4 and the slip frequency controller 5 (p, κίη match). The signals 3Ϊη [3τ., Csrp are fed directly to the inputs of the converter 17 coordinates of the compensation block 14, from the output of which three Phase EMF compensation signals are received.

The signal p, which specifies the magnitude of the EMF compensation signals, is fed to the input of the converter 17 coordinates through the scale amplifier 15 and the inertial link 16.

The scale amplifier 15 serves to provide the necessary (for each type of electric motor of its own) relationship between the signal p and the amplitude of the EMF compensation signals.

Using the inertial element 16 ensures that the dynamics of changes in the magnitude of the EMF compensation signals to the dynamics of changes in the value of the real EMF of the rotor. To ensure this compliance, the time constant of the inertial element 16 is chosen equal to the electromechanical time constant of the electric drive.

Thus, the execution of the EMF compensation unit in the form of a series-connected scale amplifier, inertial link and a coordinate converter, the reference inputs of which are connected to the outputs of the harmonic signal shaper, and the input of the scale amplifier is connected to the output of the slip frequency controller, simplifies the overall design of the proposed AC drive and increases the reliability of his work.

1488950 8

Claims (1)

Claim AC power on auth.St. No. 1037405, characterized in that, in order to simplify and increase reliability, an EMF compensation block is introduced, made of a series-connected large-scale amplifier, inertial the link and the converter of the coordinates, the reference inputs of which are connected to the corresponding outputs of the harmonizer functions, the input of the scale amplifier is connected to the output of the slip frequency regulator, and the output of the coordinate converter forms the output of the EMF compensation unit. Phie. 2