JPS5923198B2 - Control method of synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high performance servo control device using a synchronous motor.

BACKGROUND TECHNOLOGY Various types of commutatorless motors have been developed with the aim of obtaining control performance equivalent to that of a DC machine using an AC machine without brushes, but in order to obtain an exciting current distribution signal for self-controlled operation, It is necessary to separately provide a distributor for the engine, a tachogenerator for obtaining a speed feedback signal, etc., which inevitably leads to a complicated structure, and improvements have been desired.

Purpose of the Invention The present invention not only obtains the above-mentioned current distribution signal and speed feedback signal using only one detector, but also obtains a position signal for position control, thereby constructing a precise servo control system. It is something to do.

Structure of the present invention FIG. 1 shows the structure of the present invention, in which 1 is a synchronous motor;
2 is a resolver connected to the synchronous motor 1, 3 is a resolver control circuit (described later), 4 is a position command circuit (described later), 5 is a phase comparison circuit, 6 is a speed amplifier, and 78 is a first and second circuit, respectively.
Multipliers 9 and 10 are α and β phase amplifiers 4a, respectively.
5a is a position command signal, 5a is a speed command signal, and 6a is a current amplitude control signal (torque command signal).

The detection signal of the resolver 2 is input to the resolver control circuit 3, and from this resolver control circuit 3, α-phase and β-phase current command signals, a speed feedback signal, and a position feedback signal, which have an electrical phase difference of 900 degrees, are outputted. Output.

That is, as shown in FIG. 2, two-phase excitation windings 2a and 2b are wound at positions 900 different in electrical angle of the resolver 2.
is the reference clock φ.

is divided into an appropriate frequency by the frequency dividing circuit 11, and the two-phase sine wave excitation signal half Os (l) synchronized with this is -Sln
(j) (not limited to a sine wave but may also be a triangular wave) is generated by the excitation circuit 12, its output is supplied via a power booster (not shown), and the detection winding 2c is connected to the rotation of the rotor. A phase modulation signal corresponding to the angle θe [for example, Sln(
ωt+θe), where ω is the excitation angular frequency]. The detection signal of the resolver 2 is waveform-shaped by a shaping circuit 13, and frequency-divided by 1/n by a first frequency dividing circuit 15.

Further, the waveform of the output Slnωt of the excitation circuit 12 is shaped by a shaping circuit 14, and the frequency is divided by 1/n by a second frequency dividing circuit 16. The outputs of the first and second frequency divider circuits 15 and 16 are Sln (sin t) and Sin (9!-t + t), respectively, and these outputs Nnn are the outputs of the two-phase sine wave generator 35.
Input to the phase bead generation circuit ω・ω17, and here, Sln(-t)Xsln(-Tnn+
-! -e) and COs(-ψ-t)×Sln(!!2
-t+! -! -) is performed.

Here, COS (buttock t) is a signal obtained by shifting the phase of Sin (÷t) by 90, and is a signal generated within the 2n-phase bead generation circuit 17 based on Sin (sint t).

As a result of the above calculation, the low-pass filters 18 and 19 each have a value of {COSI and COS (yat+卆)}・+{Sin
! +Sin(yat+enemy)} signal is input, and after the θ high frequency component is removed, COs'・NsinO
– is output as the current command signal.

n In this case, the windings of the synchronous motor 1 have two phases, α phase and β phase, and in order to make the torque generation principle equivalent to a DC machine, each phase of the armature must be (α phase・
It is necessary to maintain the direction of the resultant magnetomotive force of the β phase) in an orthogonal relationship.

Therefore, the phase of the current command must be adjusted accordingly. As shown in the vector diagram in Figure 3, when the phase of the field magnetic flux is ψ, the α phase and
The β-phase excitation current command is IaCOSψ・−1a, respectively.
becomes sinψ.

If the number of poles of resolver 2 and synchronous motor 1 are the same, CO
Since sOe corresponds to COsψ and SinOe corresponds to Sinψ, the optimal current command can be given by mechanically adjusting the relative positions of the two. However, if a multi-pole resolver is used as the resolver 2, , divide the frequency at an appropriate timing. The frequency division ratio is determined from the pole number ratio between the resolver and the electric motor. Also, the detection signal frequency F of the resolver.

and excitation frequency ω wave number f (= pus ρ).

-f±△f (±△f is the frequency change according to the rotation speed, and the sign depends on the rotation direction.) Therefore, FO-f = ±△f = H (N: Resolver rotor , where P is the number of resolver poles). Therefore, the output of the shaping circuit 13 which shaped the detection signal of the resolver 2, and the shaping circuit 1 which shaped the waveform of the output Slnωt of the excitation circuit 12.
4 and the frequency F by f/v conversion circuits 20 and 21, respectively. If we generate a voltage proportional to -f and calculate the difference between the two using the differential amplifier 22, the output will be proportional to -f, so the output of the -120 amplifier 22 will be the rotational speed N of the synchronous motor. The electric current becomes proportional to e, and a speed feedback signal is obtained.

Furthermore, the signal obtained by waveform shaping the detection signal of the resolver 2 by the shaping circuit 13 is also introduced into the frequency dividing circuit 23, and a position feedback signal is obtained. Since a resolver is originally a position detector,
The detection signal includes position information.

That is, as shown in FIG. 4, when the rotor of the resolver 2 is stationary, the output voltage of the detection winding 2c (shaped by the shaping circuit 13) has a waveform of 1; When rotated by an angle θ, the waveform becomes a waveform whose phase is shifted by θ. The phase lead/lag depends on the direction in which the rotor rotates. Using this, PLL (PhaselOckedIO
A position control loop can be configured as a feedback signal of Op). Note that the frequency dividing circuit 23 determines the locking range of the PLL depending on the responsiveness of the control system. for example,
When using a 100-pole resolver 2,
This is because 7.20 rotations in mechanical angle means that the phase has changed by 3600 in electrical angle, and if the response of the system is slow, locking will be difficult. Next, the position command circuit 4
As shown in FIG. 5, synchronous shaping circuits 24, 25, NAND gates 26, 27, 28, 29, knot circuits 30, 31
, a frequency dividing circuit 32, a reference clock circuit 33, and a two-phase clock circuit 34.

Each clock φ. - The relationship between φA, φB, and JB is as shown in Figure 6, and while position command pulses are being applied from the outside, each position command pulse from the synchronous shaping circuits 24 and 25 is synchronized with clock φB or 7B. Output pulses shaped into pulses are output, and these pulses are added to the clock φA or a part of the clock φA is thinned out by the rotation direction command and gate operation. Next, these calculation operations will be explained with reference to FIGS. 5 and 6.

First, when no position command pulse is input, the outputs of the synchronous shaping circuits 24 and 25 are both "0", and the outputs of the NAND gates 26 and 27 are "1".

The clock φA output from the two-phase clock circuit 34 is input to the frequency dividing circuit 32 through NAND gates 28 and 29.

The output of the NAND gate 29 at this time is synchronized with the clock φA, and is shown in FIG. 6 as no position command pulse. Further, the output 4a of the frequency dividing circuit 32 at this time is shown in FIG. 6, but the frequency division ratio must be selected as follows. That is, the resolver excitation circuit 12ω shown in FIG.
Assuming that the output frequency of is f (=-) and the 2π frequency division ratio of the frequency divider circuit 23 is Np, the frequency Fp of the position feedback signal in the stationary state is Fp=! becomes.

In addition, the output signal frequency of the frequency divider circuit 32 when there is no position command pulse must be equal to f, so the frequency of the clock φA is divided by the f1 frequency divider)
A) The division ratio of 32 is N.

Then, the following formula holds true. FrfA That is, NO=completed/N.

As an example, if the resolver excitation frequency is f-4kHz and the position feedback signal frequency f is 500kHzP, then the reclocking frequency f is n-8.
) AlOOkHz
Then, the frequency division ratio N of the frequency dividing circuit 32 is.

becomes NO-200. Next, considering the case where a position command pulse is input, the synchronous shaping circuits 24 and 25 generate output signals corresponding to φB and VB, respectively, in synchronization with the position command pulse as shown in FIG.

First, when the rotation direction command corresponds to "0", one input of the NAND gate 27 is "0", so its output is always "1", and the output of the synchronous shaping circuit 25 cannot pass through the gate 27. However, one input of the NAND gate 26 is 6'', and the output of the synchronous shaping circuit 24 is the gate 26.
can pass through.

Therefore, when the NAND gate in FIG. 6 occurs, the output of the flip-flop is a square wave with a duty of 50%, and by passing this through a low-pass filter (not shown), a direct voltage of O is obtained. When a phase difference occurs, a positive or negative DC voltage depending on the direction of the phase shift is obtained from a low-pass filter (not shown). Now, when a load is applied to the motor shaft and the rotor position is displaced, the phase of the position feedback signal from the resolver 2 lags behind the position command signal, causing a positional deviation.

This deviation generates a positive DC voltage, which is input to the speed amplifier 6 as a speed command signal together with the speed feedback signal. The output of the speed amplifier 6 is used by the first and second multipliers 7 and 8 to control the amplitude of the torque flow command, and the motor rotor rotates by an angle displaced from the no-load state according to the load torque. , it stops when the position deviation disappears. Next, a rotation command of a predetermined amount is issued by a position command pulse, and FIG. 8 shows a case in which the motor rotates in the 0 direction.

When the position command pulse is given, the position command signal is phase modulated as shown in Figs. 6 and 7, creating a phase difference with the position feedback signal from the resolver 2, and by the same process as described above. Generates torque and rotates.

When the speed-up process is completed, the position command signal and the position feedback signal corresponding to the rotor position are maintained at a constant deviation, the DC voltage value is constant, and the rotor rotates at a constant speed.

When the rotation direction command is 1, the position command signal is delayed in phase as shown in FIG. 8, and the rotation is performed with a negative DC voltage.

Note that when obtaining a current distribution signal using a multipolar resolver, frequency division is required, and furthermore, it is necessary to be able to arbitrarily set the frequency division start point, which must be readjusted every time the power is turned on. For example, this problem can be solved by attaching a magnet to the resolver rotor and generating the origin pulse using a detection element such as a Hall element.

Effects of the Present Invention As described above, the present invention not only obtains a current command signal (distribution signal) and a speed feedback signal by appropriately combining and arithmetic processing the excitation signal and detection signal of the resolver.
Since the position feedback signal is also obtained and the phase deviation between the position command pulse and the synchronized position command is used to supply the synchronous motor with an alternating current having a predetermined frequency and current value, no other detector is required, and the speed feedback signal is It has the advantage that there is no pulsation even at low speeds, making the hardware configuration extremely simple.

Although a two-phase synchronous motor has been described as an example, it goes without saying that a three-phase synchronous motor can be controlled by adding a known two-phase to three-phase converter.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an overview of the control device of the present invention, Figure 2 is a block diagram showing an overview of the control device of the present invention.
The figure is a block diagram of the resolverno end 1j control circuit in Figure 1, Figure 3 is a vector diagram of the synchronous motor, Figure 4 is a resolver output waveform diagram, Figure 5 is a block diagram of the position command circuit in Figure 1, Figure 6 is a time chart showing the clock waveform supplied to the position command circuit and the operation of the position command circuit.
FIG. 8 is a time chart showing the operation of the position control loop. 1 is a synchronous motor, 2 is a resolver, 3 is a resolver control circuit, 4 is a position command circuit, 5 is a phase comparison circuit, 6 is a speed amplifier, 7 and 8 are each a multiplier, 9 and 10 are α/β phase amplifiers, 11 and 32 are frequency dividing circuits, 12 is an excitation circuit, 13 and 1
4 is a shaping circuit, 15 and 16 are first and second frequency dividing circuits, 17 is a two-phase bead generation circuit, 18 and 19 are low-pass filters, 20 and 21 are f/v conversion circuits, and 22 is a differential amplifier. , 23 is a third frequency dividing circuit, 24 and 25 are synchronous shaping circuits, 26, 27, 28, and 29 are gates, 30 to 31 are note circuits, 33 is a reference clock circuit, 34 is a two-phase clock circuit, and 35 is a It is a two-phase sine wave generator.

Claims (1)

[Claims] 1 a resolver connected to a synchronous motor, a first frequency dividing circuit that divides the detection signal sin(ω_t+θ_e) (ω: excitation angular frequency, θ_e: rotation angle) of the resolver by 1/n (n: natural number); The excitation signal sinω of the resolver
Input the output signal from the second frequency dividing circuit that divides _t by 1/n and generate the current command signal cos(θ_e_/_n)・sin
(θ_e_/_n), an f/v conversion circuit that converts the detection signal of the resolver to f/v to obtain a velocity feedback signal, and converts the detection signal of the resolver into a position feedback signal. a third frequency dividing circuit that obtains the current command; a phase comparison circuit that compares the phase of the position command signal and the position feedback signal; and a phase comparison circuit that compares the phase of the position command signal and the position feedback signal; A control device for a synchronous motor, comprising first and second multipliers that respectively multiply signals, and outputs from the first and second multipliers are used as stator current commands for the synchronous motor. .