JPS59116049A - Speed detection system of electric motor - Google Patents

Abstract

PURPOSE:To enable speed detection by using the output of a resolver by processing each of the sine wave output and cosine wave output of the resolver via a synchronous rectifying circuit, differentiating circuits, multiplier, difference circuit, etc. CONSTITUTION:The sine wave voltage ea and cosine wave voltage eb outputted from a resolver are respectively synchronously rectified in synchronous rectifying circuits 103a, 103b to outputs eta, etb. The outputs eta, etb are respectively differentiated in differentiating circuits 104a, 104b to outputs Ea, Eb. The outputs Ea, Eb are multiplied respectively by the outputs etb, eta in multipliers 104c, 104d to outputs ETa, ETb. The difference Er between the outputs ETa, and ETb is determined by an adder 104e and an actual speed voltage TSA is outputted therefrom and is fed to an arithmetic circuit. The speed detection is thus made possible by using the output of the resolver.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single-motor speed detection method that can detect the rotational speed of an electric motor based on the output of a resolver.

In order to control the speed of an electric motor, it is necessary to detect the rotational speed of the electric motor. Generally, a tachometer generator is used to detect the rotational speed of an electric motor, but since the tachometer generator is a type of generator, it is composed of worn parts such as brushes, and as it ages, it generates noise due to sparks, etc. There is a drawback that it does. A method of detecting speed using an optical encoder is also known, but it is not reliable enough because it uses components that change over time, such as a photodiode.

For this reason, there has been a need for a speed detection method that can provide sufficient reliability even against changes over time.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a speed detection method capable of detecting speed using the output of a highly reliable resolver used as a single position detector.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a configuration diagram of the resolver, and FIG. 2 is its output waveform diagram.

In the figure, 102 is a resolver connected to the shaft of the 'C4t3/I machine, which detects the position of the field pole of the electric motor.

This resolver has a rotor 102a and a rotor scroll! 102
b, two stator windings 102C and 102d arranged at 90° to each other, and a transmission wave generation circuit 102e that generates a carrier wave of s+nωt (for example, 5KH2 or 6KHZ). ing. Now 1st rotor 102a
is at the angle θ, the fixed pre-winding, Biao 10
From 2C and 102d, the voltage shown in the following formula is ea=s
1nθs1nωt (1) e b =
cosθs+nωt (2) is output. That is, H) JG shown in the 21st case,
From 02, a nine-wave voltage ea and a four-cosine wave voltage eb corresponding to the position θ of the field pole d of the floating rock are output.

Then, the sine wave voltage ea and the cosine wave direct pressure eb are expressed as Sl
The synchronous light flow at nωt is 5illθ, cos in Figure 2.
The output of θ is iM, and by this output, for example, the position of the magnetized TM in synchronous direct motion can be obtained.

Sign & from the resolver 102 configured like this
In the present invention, using the 5 pressure ea and the cosine wave kick pressure eb /lu, the speed is determined as follows.

■Sine wave 4 voltage ea, cosine wave voltage, b are Sinωt
synchronous rectification. Therefore, the synchronous rectifier circuit eta.

etb is given by the following formula, which is shown in FIG.

eta=s+nθ (3)etb=cos
θ (4) ■Next, the synchronous rectification output eta,
Differentiate etb to obtain differential output Ea, )i:b.

(2) Furthermore, the differential output Ea and the synchronous rectification output etb are multiplied by the differential output Eb and the synchronous rectification output eta to obtain multiplication outputs Era° and ETb of the following equation.

ETa - Ea x e t b - d'2 cos"θ -, t (7) ETb = Ebxeta - - d-uHn"θ dt (8) ■Additionally, the difference Er between the first power calculation output E'l'a and ETb obtain.

Er = ETa -ETb dθ = -aT (s I 112θ + cos2sdθ -2rT (9) dθ In other words, 1 stone indicates the time differentiation of the rotation angle, that is, the actual speed, and the resolver output ea.

Actual speed voltage TSA is obtained from eb.

Next, a configuration for realizing the present invention will be described using a synchronous motor as an example of the motor.

FIG. 6 is a block diagram of one embodiment of the present invention, in which 1
01 is a rotary field type synchronous movement (geometry), 102 is the above-mentioned resolver, and 106 is a synchronous rectifier circuit, which synchronously rectifies the sine wave voltage ea1 and the cosine voltage eb, respectively. 104 is a speed detection circuit to be described later, and synchronous rectification output Sinθ,
The actual speed voltage TSA is output from cos θ. 105 is an arithmetic circuit that calculates the difference (hereinafter referred to as speed error) ER between the speed command voltage VCMD commanded from a speed command circuit (not shown) and the actual speed IK'', and 106 is a calculation circuit that amplifies the speed error ER and outputs it to Error amplifiers 107 and 108 are multiplier circuits that output the current amplitude IS, and the error amplifier outputs and the outputs of the synchronous rectifier circuit 105 cosθ, sinθ・
Multiply the two-phase! Flow it output. 109 is a 2-phase to 3-phase conversion circuit for converting a 2-phase signal into a 3-phase signal, and has a circuit configuration as shown in FIG. That is, the 2-phase to 3-phase conversion circuit includes two operational amplifiers OA1. OA2, i13 have resistors R1 to R4 of Ω, a resistor R5 of 5.78Ω, and a resistor R6f of 5Ω. Now, when the values of each of the resistors R1 to R6 are determined as described above and connected as shown in the figure, the respective values are outputted from the terminals Tu, Tv, and Tw. These iu, Iv, and Iw have a phase difference of 2π/6 from each other, and the induced electromotive force E.

The 6-phase current command is in the same phase as the current command.

110U, 110V, and 110W are calculation circuits provided for each phase, respectively, and calculate the difference between the command currents 1u, Iv, and Iw and the actual phase currents 1au, Iav, and law; 111 is a calculation circuit for calculating the difference between Iav and Iaw; Arithmetic circuit that performs addition and outputs U-phase phase current iau, 112V, 112W
are galvanometers that detect the V-phase and W-phase ERIav and iaw, respectively, 113U, 115V, 113W Ha'
114 is a pulse width modulation circuit; 115 is an impark controlled by the output signal of the pulse width modulation circuit; 1
16 is a six-phase AC power supply, and 117 is a known rectifier circuit for rectifying three-phase AC into DC, which includes a diode group 117a and a capacitor 117b.

Next, the operation shown in FIG. 6 will be described in the case where the speed command increases while the synchronous motor 101 is rotating at a certain speed.

In order to rotate the synchronous motor at a desired rotational speed Vc,
A speed command '1 pressure VCMD having a predetermined analog value is input to the addition terminal of the arithmetic circuit 105. On the other hand, since the synchronous motor 101 is rotating at the actual speed Va ((Vc),
The speed detection circuit 104 outputs an actual speed voltage TSA proportional to the actual speed Va, and this actual speed voltage TSA is input to the $N4 terminal of the arithmetic circuit. Therefore, the arithmetic circuit calculates a speed error ER, which is the difference between the commanded speed Vc and the actual speed Va, and inputs this to the error amplifier 106. The error amplifier 106 performs proportional-integral calculation as shown in the following equation.

Note that (the % calculation result Is of the ID formula corresponds to the amplitude of the armature yt flow. In other words, when the load fluctuates or the speed command changes, the speed error E R (= Vc - Va) increases,
Correspondingly, the armature current amplitude Is also increases.

As Is increases, a larger torque is generated, and this torque brings the actual speed of the motor to the commanded speed.

On the other hand, since the two-phase sine wave Sin θ1 and cosine wave cos θ indicating the position (angle θ) of the field pole of the synchronous motor 101 are obtained by the resolver 102 and the synchronous rectifier circuit 103, the multiplier circuits 107 and 108 each receive signals 11a( -I
s − cos θ) e 11b (=Is−s+nθ) is obtained.

Next, the 2-phase to 3-phase conversion circuit 109 performs the calculation shown in the equation Q, 0 and outputs three-phase current commands Iu, Iv, and Iw, respectively. In addition, these Iu, "Ivjw are synchronized 'a Ai
The six-phase current command is in phase with the induced electromotive force EO of machine b 101.

After that, the 6-phase' turtle current commands Iu, Iv, Iw are converted to the actual phase current Iau by the calculation circuits 110U, 110V, 110W.
, Iav.

The difference between Iaw and Iaw is taken, and the three-phase AC signals iu, iV, iW, which are the differences, are sent to current amplifiers 115U and 1
13V.

The signal is amplified at 113W and input to the pulse width modulation circuit 114.

The pulse one-corner modulation circuit 114 compares the amplitudes of the sawtooth wave signal STS and the three-phase alternating current signals iu, iV, and iW, and sends the pulse width modulated three-phase current command to each of the power transistors Q1 to Q1 making up the inverter 115. input to the base of Q6 to turn on/off each of these power transistors Qs to Q6.
The synchronous motor 101 is controlled to be off and three-phase current is supplied to the synchronous motor 101.

Thereafter, similar control is performed and finally the synchronous motor 101
rotates at the commanded speed.

FIG. 5 is a block diagram of the synchronous rectifier circuit 106 and the speed and speed detection circuit 104 configured in FIG. 6, and in the figure, 105a.

106b is a synchronous rectifier circuit, which synchronously rectifies the sine wave voltage ea and the cosine wave voltage using the high frequency signal Sinωt that excites the rotor winding 102b of the resolver 102, and calculates the eta of the direct equation (3) and the equation (4). It outputs etb of the equation. 104a and 104b are differentiating circuits,
Each is composed of a capacitor C1 (C2) and a resistor R1 (, R2), and has a synchronous rectification output e of equations 13) and 4), respectively.
It differentiates ta, etb and outputs the differential outputs Ea and Eb of 2g (5) and (6), and its frequency gain has a linear characteristic in the speed range of the machine (frequency range of sin θ). The differential constant is determined as shown below.

104C and 104d are multiplication circuits, each consisting of an analog multiplier, and the output E of the differentiating circuits 104a and 104b.
Multiply a, Eb and synchronous rectification output eta, etb,
104e is an adder circuit that generates the multiplication outputs ETa and ETb of Equations (7) and (8), and the multiplication circuit 104
The difference Er (ie, actual speed voltage) between the multiplied outputs ETa and ETb of C and 104d is output.

Next, the operation of the configuration shown in FIG. 5 will be described. The in-wave voltage ea and the cosine-wave voltage eb output from the resolver 102 are each input to the synchronous rectifier circuit 103a.

It is synchronously rectified at 105b and becomes synchronously rectified outputs eta and etb of equations (3) and (4). Next, the synchronous rectified outputs eta and etb are differentiated by the differentiating circuits 104a and 104b, respectively, and the differential outputs Ea and E of equations (5) and (6) are
It becomes b.

Next, the differential outputs Ea and Eb are output from multiplication circuits 104G and 10
4d are respectively multiplied by the synchronous rectification outputs etb and eta, and the multiplier outputs ETa' and ET shown in equations (7,) and (8) are obtained.
It becomes b. The difference Er between the multiplication outputs ET a and ET b is taken by the addition circuit 104 e, and the actual speed voltage TSA shown in equation (9) is outputted and sent to the arithmetic circuit 105 in FIG. 3.

In the above description, the synchronous electric motor was used as an example, but the present invention can also be applied to other AC motors and even DC motors.

As explained above, according to the present invention, the sine wave and cosine wave output from the resolver are synchronously rectified in a synchronous rectifier circuit, further differentiated in a differentiator circuit, and then the differentiated sine wave and cosine wave are synchronously rectified in a multiplier circuit. The actual speed voltage is obtained by multiplying the cosine wave, the differential cosine wave, and the synchronous rectified sine wave, and the difference between the multiplication outputs is taken by a differential circuit, so the effect is that speed detection is possible using the output of the resolver. This greatly contributes to improving the reliability of electric motors and making them maintenance-free, since there is no need to use tacho generators and optical encoders, which tend to deteriorate over time and are not reliable. Further, the speed detection output can be obtained in an analog manner without any instantaneous analysis, and there is also the effect that a highly accurate actual speed voltage that is no different from a speed signal from a conventional tacho generator can be obtained. Furthermore, when applied to a synchronous motor, a SiH6, cos θ signal indicating the field pole position 1 itf and an actual speed signal can be obtained from one resolver, and there is also the effect that there is no need to provide a separate position detector.

dθ Furthermore, since the π component can be obtained directly, highly accurate speed detection that is not affected by high frequency signals is possible, and the circuit configuration is also simple, which is an extremely useful effect.

Although the present invention has been described with reference to one embodiment, various modifications can be made within the scope of the present invention, and these are not excluded from the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a resolver used in the present invention. Fig. 2 is an output waveform diagram of the configuration shown in Fig. 1, Fig. 6 is a block diagram of an example of an actual foil for realizing the present invention, Fig. 4 is a diagram of main parts of the configuration shown in Fig. 6, and Fig. 5 is FIG. 6 shows a configuration diagram of the speed detection circuit of the configuration. In the figure, 101... Electric (p, 102... Resolver,
102a... Rotor, 102b... Rotor winding, 1
02C, 102d... Stator winding, 106... Synchronous rectifier circuit, 104... Speed detection circuit, 104a, 10
4b... Differential circuit, 104 C,, 104d-...
- Multiplier circuit, 104e...Additional X circuit. Patent applicant Fanuc Co., Ltd. agent Patent attorney Sangai Tsuji 2 people

Claims (1)

[Claims] An electric resolver having a rotor and a stator that rotate together with the cylinder, a synchronous rectifier circuit that synchronously rectifies each of a sine wave output and a cosine wave output of the resolver, and synchronous rectification of the sine wave output and the synchronous rectifier. a differentiating circuit which differentiates each of the cosine wave output, the differentiated sine wave output and the synchronous rectified cosine wave output, and the differentiated cosine wave output and the synchronous rectified sine wave output, respectively. 1ii.
A method for detecting speed of electric power, characterized in that an actual speed voltage is obtained from the output of the differential circuit.