JPH0334316B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant margin angle control device for a commutatorless motor without a direct position detector.

In such a control device, the motor voltage is detected as an alternative to a direct position detector, a magnetic flux waveform is determined from this using a magnetic flux calculator, and the phase control pulse of the motor side converter (inverter) is determined using this magnetic flux waveform. There is a way to cut it out. In this case, since the quality of the magnetic flux waveform directly affects the phase error of the phase control pulse, it is necessary to be very careful in its calculation. In particular, when the torque can be reduced when the rotational speed of the motor is high, control with a so-called flux-weakening range, which weakens the magnetic flux of the motor to prevent its back electromotive force from becoming too large, is used. It is known that the relative error tends to increase as the amplitude of the magnetic flux calculation waveform decreases in the magnetic flux range. Therefore, it is desirable to stably and accurately control the constant margin angle of a commutatorless motor without a position detector even in such a flux weakening range.

FIG. 1 is a block diagram showing a conventional example of a constant margin angle control device without a position detector for a non-commutator motor using such a magnetic flux calculation waveform.

In the figure, 1 is a speed regulator, 2 is a current regulator, 3 is a firing angle regulator, 4 is a thyristor converter,
5 is a speed electromotive force calculator, 6 is an integrator, 7 is a constant margin angle pulse generator, 8 is a pulse distributor, 9 is a commutatorless motor, 10 is a tachogenerator (generator for speed detection), and SE is a speed setting The reactor and DCL are DC smoothing reactors.

After the AC power supply (3φ) is converted to DC via the power supply side converter 41, it is connected to a smoothing reactor DCL as appropriate.
The AC power is then reconverted into AC power by the motor-side converter 42, and the synchronous motor 9 is driven by the AC power. Commutatorless motor 9 configured as above
Speed control is performed by comparing the speed setting signal n ^* from the speed setting device SE with the speed detection signal n from the speed detection generator 10 directly connected to the motor and inputting it to the speed regulator 1. The output signal of the converter 1, that is, the current setting signal i ^* and the power supply side converter 41
This is achieved by comparing the AC side input current detection signal i of Ru. On the other hand, the phase control of the motor-side converter 42 is performed by determining the motor speed electromotive force E from the motor voltage V _M and the motor current I _M , and integrating this to form the waveform of the magnetic flux Φ (each phase component of the effective magnetic flux).
After obtaining this magnetic flux waveform, input the constant margin angle pulse generator 7 to the constant margin angle pulse generator 7, and input the output constant margin angle pulse with a width of 180° EL (electrical angle) to the pulse distributor 8. It is done.

The constant margin angle pulse generator 7 shown in FIG.
It is configured as shown in FIG. In addition, Fig. 2 is a block diagram showing the constant margin angle pulse generator in more detail, Fig. 3 is a waveform diagram showing the waveforms of each part in Fig. 2, and Fig. 4 is a waveform diagram showing the waveforms at rated magnetic flux and at weakening magnetic flux. It is a waveform diagram explaining the relationship between each magnetic flux waveform, control advance angle, and constant margin angle in .

In Figure 2, 71 is a 90°el phase advance circuit;
72 is a comparator, 73 is commutation overlap angle (u)
Arithmetic unit (hereinafter also referred to as u arithmetic unit), 74 is a magnetic flux absolute value arithmetic unit S ₁ to S ₃ is a switch that switches to the “1” side when each line component of magnetic flux Φ _uv , Φ _vw , Φ _wu is positive. can be,
When it is negative, it switches to the "2" side.

Its operation will be explained with reference to FIGS. 2 and 3.

Each line component (Φ _uv , Φ _vw , Φ _wu ) of the effective magnetic flux as shown in FIG.
1, each is advanced by 90°el (Φ _uv →
Φ′ _uv , Φ _vw →Φ′ _vw , Φ _wu →Φ′ _wu ). Note that this phase advance circuit 71 can be constructed by a simple addition/subtraction circuit if the input signal is a three-phase balanced input. Φ′ _uv , Φ′ _vw , Φ′ _wu obtained in this way are velocity electromotive forces E _uv , E _vw , E _wu (for example, E _uv is
It has the same phase as the velocity electromotive force between uv). On the other hand, the margin angle setting voltage V obtained by dividing the output of the magnetic flux absolute value calculator 74 and the current command value (or detected value)
and the overlap angle calculation voltage V _u obtained by the u calculator 73 from the magnetic flux absolute value are added to create the control advance angle (β) command voltage V〓. Next, the polarity of the control advance angle command voltage V〓 is switched by switches S ₁ to _{S 3} according to the positive or negative sign of the input magnetic flux waveform of each phase. The rectangular wave β command voltage (±V〓) obtained in this way is Φ′ _uv and
By comparing the magnitudes of Φ′ _vw and Φ′ _wu , a voltage/angle conversion is performed, and a constant margin angle pulse (180°el width) as shown in FIG. 3C is created. Here, the above-mentioned magnitude comparison is performed by calculating the difference between the output of the 90°el phase advance circuit 71 and the control advance angle command voltage Vβ using a subtraction circuit.
This is done by comparing the difference with a constant in the comparator 72. By the way, if there is a flux weakening range in the case of constant margin angle control as shown in FIG. 1, the amplitude of the calculated magnetic flux waveform becomes smaller accordingly. Then, there is a possibility that the angular error caused by the comparator 72 in the constant margin angle pulse generator 7 will increase. In other words, as is clear from Fig. 4, even if the β command voltage V has the same error voltage ΔV, when the angle is converted by the comparator 72, the angular error Δβ' (see Fig. 4 b) when the flux is weakened is changed. It is better to
It becomes larger than that of the rated magnetic flux waveform (see Δβ in Fig. 4 A). This becomes a problem as the flux weakening range increases.

The present invention has been made in view of the above, and an object of the present invention is to enable constant margin angle control of a commutatorless motor to be performed with high precision even in the flux weakening range.

According to the present invention, the above object is an electromotive force calculation circuit that calculates a speed electromotive force for a non-commutator motor based on the motor voltage and current of the non-commutator motor supplied by a power conversion device including at least an inverter. , an integrating circuit that integrates the electromotive force to calculate a magnetic flux waveform, and calculates the commutation overlap angle of the motor based on the magnetic flux waveform, and calculates the overlap angle and the separately set commutation margin angle of the motor. a constant margin angle pulse generation circuit that cuts out a constant margin angle control pulse having a control advance angle determined by comparing the sum of the sum and the magnetic flux waveform whose phase is advanced by 90 degrees; In a constant margin angle control device for a commutatorless motor, the control pulse is used as a gate signal to control the firing phase of an inverter in the power conversion device, and the magnetic flux is weakened by weakening the amplitude of the magnetic flux waveform calculated by the integrating circuit. This is achieved by providing a means to always maintain the maximum rated amplitude even in this area.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a block diagram showing an embodiment of the main part of the present invention, FIG. 6 is a characteristic diagram showing the relationship between the magnetic flux weakening pattern and the velocity function pattern, and FIG. 7 is a block diagram showing another embodiment of the present invention. It is.

In FIG. 5, numerals 5 to 8 are the same as those shown in FIG. 1, 11 is a multiplier, and 12 is a speed function generator. Note that this figure shows only the control circuit of the electric side converter (inverse converter).

As is clear from the figure, in the present invention, a multiplier 11 is provided between the speed electromotive force calculator 5 and the integrator 6, and a signal f( n) and speed electromotive force E
The feature is that the magnetic flux signal Φ is generated by multiplying the The signal f(n) is determined according to the pattern of magnetic flux weakening, for example, if the magnetic flux pattern is
(n), it is expressed as f(n)=K·1/Φ(n) (K is a proportionality constant). That is, in the flux weakening region shown on the right side of the dotted line in Figure 6, if the magnetic flux is weakened in inverse proportion to the speed as shown in Φ(n) in the figure, then f(n) is as shown in the figure. The pattern increases linearly. In this way, the output magnetic flux waveform of the integrator 6 will have the maximum rated amplitude even in the flux weakening range, and therefore the occurrence of angular errors in the constant margin angle pulse generator can be suppressed as much as possible. can.

As one input of the multiplier, the signal f as described above
(n) may be replaced by an inverse function signal of the magnetic flux absolute value obtained by a constant margin angle pulse generator (see FIG. 2). FIG. 7 is a block diagram showing an embodiment in such a case, and is characterized in that it is provided with an inverse function generator 13 for the absolute value of magnetic flux as described above.

As described above, according to the present invention, the amplitude of the magnetic flux waveform for extracting the constant margin angle pulse is always kept at the maximum rated amplitude even in the weakening magnetic flux range, so that an angular error occurs in the constant margin angle pulse generator. is reduced, and highly accurate constant margin angle control without a position detector is possible.

Note that the present invention can be applied to flux-weakening operation of not only DC type but also AC type commutatorless motor control systems.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional example of a constant margin angle control device for a commutatorless motor without a position detector, Fig. 2 is a block diagram showing details of a constant margin angle pulse generator, and Fig. 3 is a block diagram showing the details of a constant margin angle pulse generator. FIG. 4 is a waveform diagram showing the relationship between each magnetic flux waveform at rated magnetic flux and weakening flux, and the control advance angle and constant margin angle. FIG. 5 is a waveform diagram showing the waveform of each part of this invention. FIG. 6 is a characteristic diagram showing the relationship between the flux weakening pattern and the velocity function pattern, and FIG.
The figure is a main part block diagram showing another embodiment of the present invention. Description of symbols, 1...Speed regulator, 2...Current regulator, 3...Ignition pulse regulator, 4...Thyristor converter, 5...Speed electromotive force calculator, 6...Integrator, 7... ...Constant margin angle pulse generator, 71...
90°el phase advance circuit, 72...Comparator, 7
3... u computing unit, 74... magnetic flux absolute value computing unit, 8
... Pulse distributor, 9 ... Commutatorless motor, 10
...Tachogenerator, 11...Multiplier, 12...
Function generator, 13...Inverse function generator.

Claims (1)

[Scope of Claims] 1. An electromotive force calculation circuit 5 that calculates the speed electromotive force of a non-commutated motor based on the motor voltage and current of the non-commutated motor supplied by a power conversion device including at least an inverter; An integrating circuit 6 integrates the electromotive force to calculate a magnetic flux waveform, and calculates a commutation overlap angle of the motor based on the magnetic flux waveform, and combines the overlap angle with a separately set commutation margin angle of the motor. a constant margin angle pulse generation circuit 7 that extracts a constant margin angle control pulse having a control advance angle determined by comparison with the magnetic flux waveform whose sum and phase are advanced by 90 degrees; In a constant margin angle control device for a commutatorless motor, the firing phase of an inverter in the power converter is controlled using a control pulse as a gate signal, the amplitude of the magnetic flux waveform calculated by the integrating circuit 6 is weakened. A constant margin angle control device for a commutatorless motor, characterized in that means 11, 12, and 13 are provided to always keep the amplitude at the maximum rated amplitude even in the magnetic flux region.