JPH0161031B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for a synchronous motor, and more particularly, to a speed control device for a synchronous motor. The present invention relates to a drive control device for a synchronous motor.

In synchronous motors, such as DC brushless motors, in which a permanent magnet is installed on the rotor side to form a field and an exciting current is applied to the stationary side, the generated torque changes somewhat depending on the rotational position of the permanent magnet. When a synchronous motor is used as a servo motor, the generated torque fluctuates, especially at the time of starting, which is not constant, which is undesirable. Regarding a magnet motor in a synchronous motor, Japanese Patent Application Laid-Open No. 54-68914 ``DC Brushless Motor'' is already known.

In this prior art, as shown in FIG. 1, a method is shown in which a magnetically sensitive element such as a Hall element is used to suppress fluctuations in torque due to the rotational position of a brushless motor.

As shown in the figure, the output of the Hall element changes under the influence of the magnetic field corresponding to the angle of the rotor of the brushless motor, is input to the pulse width modulation circuit PWM, and the output is given to the armature winding of the brushless motor. It is intended to do so.

However, in the control method shown in Figure 1, (a) it is necessary to install the Hall elements with a 90° phase difference from each other, and it is necessary to maintain that installation condition, and (b) it is necessary to change the temperature characteristics of the Hall elements. Various problems have been pointed out, such as (c) the need to use a detector for feedback control of both position and speed when using it for driving machine tools, etc. can.

Figure 1B is a block diagram showing the principle of the present invention.Compared with Figure 1B, a device that generates a phase modulation signal, such as a resolver, is attached to the output shaft of the motor. The purpose is to control the rotation speed.

An object of the present invention is to provide a control device that rotates a synchronous motor with a constant torque using signals from a detector that emits a phase modulation signal, such as a resolver or an inductor, which is normally used for motor position feedback. Another object of the present invention is to obtain a speed feedback signal directly from the phase modulation signal, that is, to obtain a synchronous motor drive control device in which both position and speed feedback signals are obtained from one detector. Another object of the present invention is to provide a drive control device that electrically adjusts the mounting state of a motor, a resolver, etc.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 8.

In FIG. 2, reference numeral 11 denotes a numerical control device, and within the control device 11 there is provided a speed command value generating section 11-1 that gives Vref to the command value voltage Nr corresponding to the rotational speed value of the synchronous motor 20. There is. 11-
Reference numeral 2 denotes a calculation unit that calculates the amount of position feedback.
(ωt+θ) is input.

Reference numeral 12 denotes an adder which outputs the command value voltage Vref corresponding to the command speed and the output K2 _· E of the speed signal converter 15.
The difference voltage between dθ/dt (hereinafter referred to as error signal ERR) is calculated. 13 is an amplifier that amplifies the error signal ERR by a factor of _K1 , and 14 is a multiplier whose A terminal receives the output _K1 ·ERR of the amplifier 13, and its B terminal receives the phase modulation signal which is the output of the detector 21. Signal Esin(ωt+
θ) is input, so its output is K ₁・ERR・Esin(ωt+θ)=EK ₁ (Vref−K
₂ Edθ/dt)・sin(ωt+θ). 16 is a synchronous rectifier which converts the output of the multiplier 14 into a reference signal.
Synchronous rectification is performed with S1. Reference numeral 17 denotes a power amplifier whose output is applied to a winding corresponding to one pole of the synchronous motor 20.

Also, the output of the multiplier 14 is another synchronous rectifier 1
8, is synchronously rectified by the reference signal S2, and is further applied to the winding corresponding to the other pole via the power amplifying section 19. Here, the signals S1 and S2 are voltages of rectangular waves S1 and S2 or sine waves S1S and S2S, which are given by the oscillator 23 and have a phase difference of 90 degrees from each other. In the case of a sine wave, S1S=Esin (ωt+θ) S2S=Ecos (ωt+θ) It is.

The detector 21 receives the phase modulation signal Esin as described above.
(ωt+θ) and is rotationally driven from the output shaft of the electric motor 20, a resolver can be used as a detector.

Further, when a phase modulation signal is extracted via a moving body linearly moved by the electric motor 20, an inductosin can be used as the detector.

The detector 21 is supplied with the above-mentioned excitation voltage S1,
S2, S1S, and S2S are used.

Reference numeral 15 denotes a speed signal converter for obtaining a speed signal with respect to θ, that is, a time differential signal dθ/dt from the phase modulation signal Esin (ωt+θ). There are various methods for obtaining the speed signal from the phase modulation signal. For example, a method is known in which θ is first extracted through digital processing and then differentiated with respect to time, as shown in FIG. 3, but the circuit configuration is relatively simple. Since the process becomes complicated, it is preferable to use a circuit configuration based on an analog processing method as shown in FIG.

The output K ₂ Edθ/dt (see FIG. 4) of the speed signal converter 15 is input to the adder 12 as described above to form the error signal ERR. 22, the mounting state of the detector 21 is precisely adjusted so that θ=0 when the direction of the rotating shaft of the synchronous motor 20 is at a certain angular position with respect to the signal θ included in the output of the detector 21, that is, when maximum torque is generated. This is a phase adjustment circuit for electrically adjusting this shift when it is difficult to set the phase difference. (See FIG. 7 for details.) In place of the speed signal converter 15 described above, a position signal converter 11 is provided in the numerical control device 11.
A method of time-differentiating the signal θ given here using -2 will be explained. As shown in FIG. 3, the position signal converter 11-2 normally converts the phase modulated signal Esin from the rising time of the reference signal S1 (in the case of a rectangular wave).
The time when (ωt+θ) crosses zero (t1, t2, etc.)
Find the numbers n1 and n2 of clock pulses intervening in the phase differences θ1 and θ2 between. Now considering Δn = |n2 − n1|, this Δn is one period of the excitation signal 1/(ω/
2π)=corresponds to the amount (angle) of rotation of the synchronous motor 20 during Δt. Therefore, if ω is sufficiently large to meet the accuracy for speed detection, this Δn corresponds to the amount of rotation (amount of movement) during one period Δt, that is, the speed. Therefore, 11-3 shown by the broken line in Fig. 2 is calculated by calculating this Δn and converting it into D/A.
The converter 15 can be replaced by a converting circuit configuration.

FIG. 4 shows an example of a detailed circuit of the speed signal converter 15 using a two-pole DC brushless motor 20A as the synchronous motor in FIG. Also, the same elements as in FIG. 1 are given the same numbers.

The rotor 20A-3 of the motor 20A is equipped with a permanent magnet as a field pole, while the fixed side is equipped with a permanent magnet as a field pole.
The cos winding 20A-1 and the sine winding 20A-2 are connected to each other.
They are arranged with a phase difference of 90°.

The rotating shaft of a resolver 21A is coupled to the shaft 24A of the rotor 20A-3 as a detector, and the primary windings 21A-1, 21A-2 of the resolver 21A are connected to the shaft 24A of the rotor 20A-3.
Esinωt and Ecosωt are input from the oscillator 23 to . Secondary winding 21A-3 of resolver 21A
is given a phase modulation signal regarding θ such as Esin(ωt+θ).

This phase modulation signal Esin (ωt+θ) is applied to the multiplier 14
The multiplier 14 is further connected to the multiplier 14 via a circuit means 22 for adjusting the phase of the phase modulated signal when inputting the phase modulated signal to the multiplier 14.
It is used as an input to

In this phase adjustment circuit 22, the signal Esin(ωt
+θ) by changing the phase by Esin(ωt+θ−). By adjusting the phase angle θ to θ− in this way, the secondary winding 21A of the resolver 21A
-3 and the field pole of the motor 20A is corrected for the installation error Δθ. By providing the electrical phase adjustment circuit 22 in this way, it is possible to convert mechanical phase adjustment, which requires precise adjustment work, into an electrical adjustment method.

The phase adjustment circuit 22 can be implemented by a phase delay (lead) circuit consisting of a resistor and a capacitor, as shown in FIG.

Next, a circuit block diagram of an embodiment of the speed signal detection section 15 shown in FIG. 4 will be explained. In the figure, the phase modulation signal Esin(ωt+
θ) is input. Therefore, the output of the differentiating circuit 15-1 is E(ω+dθ/dt)cos(ωt+θ) as shown in the figure. Differentiator circuit 15-1 output is selective amplifier circuit 1
5-3 and a waveform shaping circuit 15-2.

The waveform shaping circuit 15-2 shapes the differential output wave into a rectangular wave, and the obtained rectangular wave is expressed as a Fourier series as Eωcos(ωt+θ)+Σf(nωt).

The selection amplifier 15-3 amplifies the component related to the fundamental frequency (ω/2π) of the difference between the differential output and the waveform shaping circuit output, that is, the difference [Eωcos (ωt+θ)+Edθ/dtcos (ωt+θ)]− [
Eωcos(ωt+θ)+Σf(nωt)] = Edθ/dtcos(ωt+θ)−Σf(nωt) is amplified by K2 only for ω/2π, so the output is given as _{K 2 Edθ} /dtcos(ωt+θ).

15-4 is a transformer which outputs the output signal K ₂ E
Remove the drift of dθ/dt・cos(ωt+θ). The secondary side signal K ₂ Edθ/dtcos (ωt+θ) of the transformer 15-4 is synchronously rectified by a synchronous rectifier circuit 15-5 using the output signal of the waveform shaping circuit 15-2 as a reference signal. Therefore, the output N of the circuit 15-5 is N=K ₂ Edθ/dt.

Further, in FIG. 4, the output of the multiplier 14, _K1・(Nr−N)・Esin(ωt
+θ−) is input. Therefore, synchronous rectifier circuit 1
The output of 6 is K ₁ E(Nr-N)cosθ. The power amplification section 17 includes a signal addition section 17-1 and a current control amplifier 1.
Current is supplied to the cos winding of the motor 20A via the pulse width modulation circuit 7-2 and the pulse width modulation circuit 17-3. Further, the current supplied to the cos winding is fed back to the adding section 17-1 through the current detecting section 17-4. Also sin winding 20A-
2, the circuits 18, 19-1, 19-2,
19-3 and 19-4 are shown as having similar configurations.

5A shows the circuit pulse width modulation circuit 17-3 block of the synchronous rectifier circuit 16 and power amplification section 17 in FIG. 4, and FIG. 5B shows the current detection section 17-4 and the motor 2
The connection between the 0A cos winding and the sine winding is shown.
~G4 is input and gate signal for cos winding
G1 and G4 are also gate signal G2 for sin winding,
Current is supplied when G3 is in the ON state.

For example, when the gate signal G1 is ON, the current ic flowing to the cos winding is from the (+) side of the power supply Vcc1 to the collector of Tr1 → emitter → resistor RC → cos winding → point CM →
It flows like (-) of Vcc. The current detecting section 17-4 in FIG. 5A corresponds to the resistor RC and is adapted to extract the voltage drop Vc across the resistor RC. Similarly, the resistor RS corresponds to the current detection section 19-4 for the sin winding.

FIG. 6 shows a general circuit configuration of the differential circuit 15-1 shown in FIG. 4, consisting of a resistor 15-1A and a capacitor 15-1B. Figure 7 shows the adjustment circuit 2 in Figure 4.
2, which is an operational amplifier 22-
The input resistor 22- is connected to the (minus) input terminal T of 9.
1, variable resistor 22-2, capacitor 22-
3. A resistor 22-4 is connected. Also resistance 22
-8, 22-6, and capacitor 22-7 form a feedback circuit. By adjusting the variable resistor 22-2, the output becomes -Esin(ωt+θ-) with respect to the input signal Esin(ωt+θ), which can correspond to either positive, negative, ie, phase lag, or lead. 22-5 is a resistor provided between the ground G and the ground G.

FIG. 8 shows a circuit embodying the synchronous rectifier 16 of FIGS. 2 and 4. In FIG.

16A is a shaping circuit that shapes the input signal (switching signal for synchronous rectification) S1S into a rectangular wave, and 16-1 and 16-2 are amplifier circuits that shift the phase of the input signal to it by π. .

Switching 1 to transistor FET1 is performed when the rectangular wave signal S1QA, which is the output of the amplifier circuit 16-1, is high.
When the level (logic 1) is high, gate g1 becomes H level, therefore FET1 is in ON state, and while S1QA=1, the output of multiplier 14 is K ₁ E (Nr - N) sin (
−) is a positive sign, source So1, drain dr
1 and is input to the adder 16-3 via the resistor ra.

Furthermore, when the signal S1QA is at L level (logic = 0), the rectangular wave signal S1QA is at H level, and at that time, the output of the multiplier 14 has a negative sign, and the output signal is inverted by the amplifier circuit 16-2. It becomes a positive signal and is given to the source So2 of transistor FET2, and since FET2 is currently in the ON state, the drain dr
2. It is input to the adder 16-3 via the resistor rb. Therefore, the output of adder 16-3 is multiplier 1.
The output of 4 is synchronously rectified using signal S1 (sinωt) as a reference signal (full wave rectification) signal K ₁ E (Nr - N)
cosθ is now given.

The motor 20A in Figure 4 above uses a 2-pole motor as an example, but in the case of a 4-pole, 6-pole, etc.
The outputs of 7-3 and 19-3 may be branched and applied to each winding.

As explained above, in the present invention, a detector that gives a phase modulation signal, such as a resolver or an inductosyn, is used as a detector to obtain a speed signal outside the position, so that the speed signal can be It is advantageous when used in a servo drive system of a numerically controlled machine tool, etc., since there is no need to install a tachometer generator or the like to obtain this.

Further, in the present invention, a multiplier is used to input the phase modulation signal Esin(ωt+θ) as one input signal.
This multiplier output is synchronously rectified, then power amplified and applied to the sine and cosine windings of the motor, respectively, resulting in a simpler analog circuit configuration than conventional systems.

Furthermore, in the present invention, since an electrical phase adjustment circuit (adjustment) is used, the resolver,
The work of installing the inductosin is greatly simplified compared to the conventional case. Furthermore, in the present invention, by implementing the speed signal detector with a simple analog circuit using a differentiating circuit, a selective amplification circuit, etc., the entire system that receives the command voltage Nr as an input, as shown in FIG. forms a controller for the motor 20A, which has an analog circuit configuration.
By combining these into a unit, it is possible to construct a single speed control device, and it is possible to avoid the complexity of the digital control system currently seen in drive systems of machine tools. That is, the servo drive system can be constructed separately from the numerical control device that provides the signal Nr.

[Brief explanation of drawings]

Figures 1A and 1B are block diagrams explaining the principles of the conventional system and the system of the present invention, Figure 2 is a block diagram of the main part of the drive control device according to the present invention, and Figure 3 is a system obtained by digitally processing speed signals. FIG. 4 is a circuit configuration block diagram when the present invention is applied to a two-phase brushless synchronous motor, FIG.
A circuit diagram that forms the current flowing to the cos winding, Figure 6 is an example circuit diagram of a differential circuit, and Figure 7 is a phase adjustment (
Adjustment) circuit diagram, FIG. 8 is a synchronous rectification circuit diagram. 11... Numerical control device, 14... Multiplier, 15
... Speed signal detection section, 16, 18 ... Synchronous rectification circuit, 17, 19 ... Power amplification section, 20 ... Synchronous motor, 21 ... Phase modulation signal generation section, 22 ... Phase adjustment circuit, 23 ... oscillator.

Claims (1)

[Claims] 1. A drive control device for a synchronous motor, which is driven in response to the rotation of an output rotation shaft of the motor and generates a phase modulation signal Esin (ωt+θ) that includes a rotation angle θ of the motor rotation shaft. a differentiating circuit for time-differentiating the phase-modulated signal, a waveform shaping circuit for shaping the time-differentiated signal into a rectangular wave, and a difference between the time-differentiated signal and the waveform shaping circuit output as a fundamental frequency ω. /2π, and a synchronous rectification circuit that synchronously rectifies the output of the selection amplification circuit by using the output of the waveform shaping circuit as a reference signal, and corresponds to the time differentiation of the rotation angle signal θ from the phase modulation signal. a speed signal detection unit that forms a signal (K ₂ Edθ/dt); a speed command value signal generation unit that provides a command value signal (Vref) corresponding to the rotational speed of the motor; and the speed signal detector output K ₂ E (ERR=Vref−K ₂ Edθ/dt); a signal amplifier that amplifies the output of the adder; a multiplier for calculating the product of ωt + θ); the output of the multiplier is branched to supply the sine winding and the cosine winding of the motor, respectively; and the carrier frequency of the phase modulation signal is ω/2π; A drive control device for a synchronous motor, characterized in that it comprises a synchronous rectifier circuit and a power amplification section that synchronously rectify each of the branched multiplier outputs using reference signals S1 and S2 having a phase difference. 2. In claim 1, a phase adjustment circuit is provided on the line into which the phase modulation signal of the multiplier is input, and Esin (ω + θ-) is adjusted to Esin (ω + θ).
A drive control device for a synchronous motor, characterized by adjusting the phase as shown in FIG. 3. A drive control device for a synchronous motor according to claims 1 and 2, characterized in that a resolver is used as the phase modulation signal generating means.