JP2538624B2 - Brushless motor drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention is directed to a brushless motor configured to detect the position of a rotor based on an induced voltage induced in an armature winding of each phase. Drive device.

(Prior Art) A brushless motor is configured to detect the position of a field magnetic pole arranged on the rotor side and control the on / off switching of an armature winding arranged on the stator side according to the detected position. As a method for detecting the position of the field magnetic poles in such a configuration, there has recently been provided a method that utilizes the fact that a voltage is induced in the armature winding of each phase as the rotor rotates, and a conventional example thereof. Is shown in FIG. Here, 1 is a DC power supply, 2 is a three-phase armature winding 4u, 4v,
An output circuit 5 which controls the interruption and interruption of 4w, an induced voltage detection circuit 5 which detects a voltage induced in the armature winding of each phase, and a magnetic pole position detection circuit 6. The magnetic pole position detection circuit 6 generates a phase-to-phase detection voltage corresponding to the difference between the induced voltages of the respective phases detected by the induced voltage detection circuit 5, and detects the zero-cross point of the phase-to-phase detection voltage to shift by 120 °. It also outputs a magnetic pole position detection signal with a pulse width of 180 ° (both are electrical angles). Specifically, the induced voltage in the armature winding of each phase becomes as shown in FIGS. 6 (A) to 6 (C) as the field magnetic pole 7 of the rotor rotates. Are trapezoidal waves shown in (D) to (F) of the figure, and the magnetic pole position detection signal S is pulsed based on these gelocross points.
I, S II, and S III are as shown in (G) to (I) of FIG.
These magnetic pole position detection signals SI, S II, S III are the logic circuit 8
And the energization timing signals ((J) to (O) in the same figure) with a pulse width of 120 ° for controlling ON / OFF of the six switching elements 3 respectively are obtained. Then, based on this energization timing signal, the control circuit 9 controls on / off of each switching element 3 of the output circuit 2.

By the way, in this type of motor, as the armature current increases, the air gap magnetic flux is distorted due to the effect, so that the electrical neutral axis moves from the geometric neutral axis to the side opposite to the rotation direction. Armature reaction is inevitable. However, in the above-mentioned conventional configuration, since the energization timing signal is only obtained with reference to the zero-cross point of the interphase detection voltage, the energization timing signal from the optimum time point for torque generation becomes large with an increase in the armature current, In addition to causing a decrease in efficiency, there is a problem that in the worst case, rectification failure occurs.

To solve such a problem, for example, the technique described in Japanese Patent Publication No. 61-59073 is also provided. This is to detect the line voltage and phase current for two phases, calculate the three-phase line electromotive force, integrate each of these to find the three-phase magnetic flux waveform, and then use this magnetic flux waveform as the phase reference. The effect of the armature reaction is corrected by applying the signal as a signal and a signal proportional to the magnitude of the armature current.

(Problems to be Solved by the Invention) In the above configuration, since the phase reference signal is the magnetic flux waveform, the signal amplitude does not depend on the rotation speed, and stable control is possible even in the low speed range, and the armature reaction There is an advantage that proper rectification can be performed even if there is distortion of the magnetic field due to. However, with the above-described configuration, the number of detection elements such as voltage and current increases, and a circuit for processing those signals is required. Therefore, it is inevitable that the configuration becomes complicated as a whole. Further, since the line electromotive force is integrated to shift the phase by 90 ° in order to obtain the magnetic flux waveform, there is a disadvantage that sufficient followability cannot be obtained even for rapid speed fluctuations.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable stable control without being affected by the rotation speed of a motor, and to appropriately commutate even if there is magnetic field distortion due to armature reaction. It is an object of the present invention to provide a drive device for a brushless motor, which is capable of simplifying the structure and capable of high-speed response to speed fluctuation.

[Configuration of Invention] (Means for Solving Problems) A brushless motor drive device according to the present invention detects an induced voltage that detects a voltage induced in an armature winding of each phase as a rotor rotates. Means, reference voltage generating means for generating a reference voltage having a pulse height proportional to the voltage applied to the armature winding and the armature current and having a pulse width according to the rotation speed of the rotor, and the induced voltage Magnetic pole position detection means for outputting a magnetic pole position detection signal by comparing the reference voltage with the interphase detection voltage corresponding to the potential difference between any two phases among the induced voltages of each phase detected by the detection means, and the magnetic pole. Control means for outputting an energization timing signal based on the position detection signal and an output for controlling energization / disconnection of the armature winding of each phase by turning on / off the switching element based on the energization timing signal. Those having features was constructed to and a circuit.

(Operation) According to the above means, the interphase detection voltage corresponding to the induced voltage difference of each phase has a trapezoidal wave shape, and the reference voltage to be compared with this increases in proportion to the increase of the armature current.
As a result, the magnetic pole position detection signal output from the magnetic pole position detection means, and hence the energization timing signal, are out of phase in proportion to the magnitude of the armature current, thereby correcting the influence of the armature reaction. In this case, since the measuring element only needs the induced voltage and the armature current induced in the armature winding of each phase, the structure is simplified, and since the integral operation is not performed, high speed response is also possible. Moreover, when the voltage applied to the armature winding is low and the motor rotation speed is low, the induced voltage and thus the phase-to-phase detection voltage are low, but the reference voltage output from the reference voltage generating means is also reduced accordingly. Since the voltage decreases in proportion to the voltage applied to the line, stable control is possible without being affected by the rotation speed of the motor.

(Embodiment) An embodiment in which the present invention is applied to a brushless motor of three-phase, four-pole, 120 ° energization system will be described with reference to FIGS. 1 to 4.

First, the overall circuit configuration will be described. On the stator side of the brushless motor, Y-connected 3-phase armature windings 10u, 10
v and 10w are arranged, and a field pole 11 composed of a permanent magnet is arranged on the rotor side. On the other hand, 12 is a variable output voltage type DC power supply, and 13 is an output circuit configured by connecting six switching elements 14 in a three-phase bridge.
By turning on / off each of the switching elements 14, the on / off of the electric element windings 10u, 10v, 10w of each phase is controlled. Induced voltage is detected by three sets of voltage dividing circuits, which consist of two resistors 15 and 16 connected in series between each phase terminal U, V and W of the armature winding 10u to 10w and the ground line. Means 17 is configured, by which the induced voltage induced in the armature windings 10u to 10w of each phase according to the rotation of the rotor and by extension of the field magnetic pole 11 is divided at a predetermined division ratio, and this is divided for each phase. Magnetic pole position detection means
Output to 18. In the magnetic pole position detection means 18, between any two phases (U-V phases, V) among the divided induced voltages of each phase.
-W phase, W-U phase) three types of interphase detection voltages corresponding to each potential difference are generated, and the interphase detection voltages and the reference voltages Vr1, Vr2, from the reference voltage generating means 19 described later in detail.
Vr3 is compared, and magnetic pole position detection signals SSI, SII, SIII based on the comparison result are output to the logic circuit 20. These magnetic pole position detection signals SI to SIII are shown in FIG.
Similar to the one shown in (I), the pulse signals have a width of 180 ° (both are electrical angles) deviated from each other by 120 °, and the logic circuit 20 is based on the position detection signals SI to S III and is similar to the conventional one. , Generates an energization timing signal having a pulse width of 120 ° for controlling on / off of each switching element 14 of the output circuit 13, and outputs the energization timing signal to the drive circuit 21. The logic circuit 20 and the drive circuit 21 function as the control means 22 in cooperation with each other, and the switching elements 14 of the output circuit 13 are turned on and off based on the energization timing signal, so that the armature windings 10u to The disconnection of 10w is controlled.

Now, the reference voltage generating means 19 includes a bus of the DC power supply 12.
A voltage signal Sv corresponding to the voltage applied to the armature winding from 12a, 12b and a current signal Si corresponding to the armature current are given from the current detector 23. The concrete configuration of the reference voltage generating means 19 is shown in FIG. 2, in which 24 is the voltage signal Sv
A level conversion circuit for converting to the L level, 25 is a current-voltage conversion circuit for converting the current signal Si into a voltage proportional to the current, 26
It is a voltage generation circuit that generates a voltage proportional to both the voltage signal Sv and the current signal Si. 27 is a delay circuit for delaying the rotation speed signal received from the control means 22, and since the pulse widths of the magnetic pole position detection signals SI to S III correspond to the rotation speed, in this embodiment, the control means 22 The position detection signals SI to SIII are used as rotation speed signals. 28 is a positive / negative switching circuit, which outputs a positive output voltage of the voltage generation circuit 26 when the delayed magnetic pole position detection signal is at a high level, and outputs a negative output voltage when it is at a low level. Output. The output voltage from the positive / negative switching circuit 28 is output to the magnetic pole position detecting means 18 as the reference voltages Vr1, Vr2, Vr3, and the pulse width of the rotation speed signal is inversely proportional to the rotation speed of the rotor. , After all, the reference voltage
The pulse heights of Vr1, Vr2, Vr3 are proportional to the voltage applied to the armature winding and the armature current, and the pulse width is inversely proportional to the rotation speed. In the magnetic pole position detecting means 18, U
The reference voltage compared with the interphase detection voltage of the −V phase is the reference voltage Vr2 generated by the reference voltage generation means 19 based on the magnetic pole position detection signal S II, and is compared with the interphase detection voltage of the VW phase. The reference voltage is the reference voltage Vr3 generated based on the magnetic pole position detection signal S III, and the reference voltage that is compared with the W-U phase detection voltage difference is the reference voltage Vr1 generated based on the magnetic pole position detection signal SI.

 Next, the operation of the above configuration will be described.

Now, assuming that the rotor is rotating, induced voltages as shown in FIGS. 6A to 6C are generated in the armature windings 10u to 10w of the respective phases. This induced voltage is detected and divided by the induced voltage detecting means 17 and given to the magnetic pole position detecting means 18,
Here, FIG. 6 (D) -corresponding to the difference in the induced voltage between each phase.
A trapezoidal interphase detection voltage as shown in (F) is generated. On the other hand, if the rated voltage is output from the DC power source 12, the level conversion circuit 24 of the reference voltage generating means 19 outputs a 100% voltage signal Sv as shown in FIG. 3 (A). If the armature current is at the rated value,
As shown by the solid line in FIG. 3B, the current-voltage conversion circuit 25 outputs a 100% current signal Si. Then, in this case, the voltage generation circuit 26 outputs the 100% current signal Si as it is, as shown by the solid line in FIG. Further, the magnetic pole position detection signals SI to SIII of each phase are given to the delay circuit 27 of the reference voltage generating means 19 as rotation speed signals. One phase of this is shown in FIG. 3 (D), which is delayed by the delay circuit 27 as shown in FIG. 3 (E) to the positive / negative switching circuit 28 for each phase. Given.
In the following description, the operation of each phase is temporal in terms of electrical angle.
Since there is a 120 ° offset relationship, only one phase will be described. That is, the positive / negative switching circuit 28 outputs the voltage of the voltage generation circuit 26 with a positive polarity when the rotation speed signal is at the high level, and conversely, when the rotation speed signal is at the low level, the output voltage of the voltage generation circuit 26. Is output as a negative polarity, and in the end,
When the signals shown in FIGS. 3C and 3D are given, the positive / negative switching circuit 28 outputs the reference voltage as shown by the solid line in FIG. And magnetic pole position detection means
In 18, as described above, three types of trapezoidal waveform interphase detection voltages are generated, which are compared with the reference voltages Vr1 to Vr3, and become high level while the reference voltage is higher than the interphase detection voltage, and conversely. Magnetic pole position detection signal that becomes low level while the reference voltage is lower than the interphase detection voltage
SI to S III are generated. This state is illustrated by solid lines in FIGS. 3 (G) and 3 (H). The magnetic pole position detection signals SI to SIII thus obtained are given to the control means 22, and here, based on the signals, FIG. 6 (J) to FIG.
An energization timing signal having an electrical angle width of 120 ° as shown in (O) is generated, and each switching element 14 of the output circuit 13 is turned on / off based on the energization timing signal to disconnect the armature windings 10u to 10w. Controlled.

Now, when the rotor is rotating in the rated state in this way, a relatively large armature reaction occurs due to the influence of the rated value of the armature current. However, in this embodiment, instead of comparing the interphase detection voltage with a constant zero-cross point,
Since the comparison is made with the reference voltage proportional to the armature current, the phase of the position detection signal is shifted by the angle α shown in FIG. 3 (G) to correct the shift of the electrical neutral axis due to the armature reaction. You can Further, when the load torque decreases and the armature current reaches, for example, 50% of the rated value, the armature reaction decreases accordingly. However, in this embodiment, in this case, the current-voltage conversion circuit 25
Output voltage is 50% as shown by the broken line in FIG. 3 (B), and the reference voltage is also half the pulse height as shown by the broken line in FIGS. 3 (F) and (G). That is, the pulse height of the reference voltage decreases in proportion to the armature current. Therefore, the deviation angle of the magnetic pole position detection signal from the zero cross point is shown in FIG.
As shown in (4), the value becomes smaller than α during the rated operation, so that it is possible to obtain the optimum energization timing signal that can appropriately correct the deviation of the electrical neutral axis due to the armature reaction.

On the other hand, the output voltage of the DC power supply 12 and the armature winding 10u
Assuming that the voltage applied to ~ 10w is, for example, 50% of the rated value and the rotation speed is about half the rated value, the induced voltage induced in the armature windings 10u to 10w of each phase is the rated value. It is halved during operation, and eventually the interphase detection voltage applied to the magnetic pole position detection means 19 is also halved. However, in this embodiment,
In this case, the output voltage of the level conversion circuit 24 of the reference voltage generating means 19 becomes 50% output as shown in FIG.
Assuming that the armature current remains at the rated value, the output of the voltage generation circuit 26 will also be 50% as shown by the solid line in FIG. 7C, and eventually the reference voltage will be applied to the armature windings 10u to 10w. In proportion to the applied voltage, the value becomes 50% of that in the case of FIG. 3 (F) as shown by the solid line in FIG. Therefore, even if the interphase detection voltage becomes half as compared with the case of FIGS. 3 (G) and (H) as shown by the solid line in FIGS. Also, since the magnetic pole position detection signal has a deviation angle of α as in the case of FIG. 3 in which the rated voltage of FIG. 3 is applied, the armature reaction can be appropriately corrected. Thus, regardless of the rotation speed of the rotor, that is, even when the rotor rotates at a low speed, the armature reaction can be appropriately corrected and stable control can be performed. When the voltage applied to the armature windings 10u to 10w is half of the rated value and the armature current is also half of the rated value, as shown by the broken line in FIG. In this case as well, as in the case of FIG. 3, the armature reaction can be appropriately corrected by reducing the deviation angle of the magnetic pole position detection signal as the armature reaction becomes smaller.

Moreover, in the present embodiment, as described above, not only can the armature reaction be appropriately corrected depending on the degree thereof and regardless of the rotation speed of the rotor, but the integration operation is not performed in the signal processing process as in the conventional case. Can enable fast response. Moreover, since the measurement element only needs the induced voltage and the armature current of the armature windings 10u to 10w of each phase, the entire configuration can be simplified.

In the above embodiment, the induced voltage of the armature windings 10u to 10w of each phase is directly detected from each phase terminal U, V, W, but the present invention is not limited to this, for example, the wire The detection may be performed based on the inter-voltage or the like, or the line current may be detected without necessarily detecting the current in the bus from the DC power supply 12. In addition, it is possible to carry out various modifications without departing from the scope of the present invention in which some of the functions are processed by a microcomputer without achieving all the functions in a so-called hardware manner.

[Effects of the Invention] As described above, according to the present invention, the interphase detection voltage corresponding to the potential difference between any two phases among the induced voltages induced in the armature windings of each phase is calculated as the armature current and the armature voltage. The armature reaction can be stably corrected without being affected by the rotation speed because the comparison is made with the reference voltage having the pulse height proportional to the pulse width and the pulse width corresponding to the rotation speed. This has an excellent effect that simplification and speeding up of response to speed fluctuation can be realized.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is an overall block diagram, FIG. 2 is a block diagram of a reference voltage generating means, and FIG. 3 is a voltage waveform of each part during high speed rotation. Figure,
FIG. 4 is a diagram corresponding to FIG. 3 at low speed rotation, FIG. 5 is a diagram corresponding to FIG. 1 showing a conventional example, and FIG. 6 is a voltage waveform diagram of each portion in the conventional example. In the drawing, 10 is an armature winding, 11 is a field magnetic pole, 13 is an output circuit, 14 is a switching element, 17 is an induced voltage detecting means, 18
Is a magnetic pole position detecting means, 19 is a reference voltage generating means, and 22 is a control means.

Claims (1)

(57) [Claims] 1. An armature winding for each phase arranged on the stator side,
Induction voltage detection means for detecting a voltage induced in the armature winding of each phase as the rotor rotates, in which current is sequentially supplied depending on the position of the field magnetic poles arranged on the rotor side. A reference voltage generating means for generating a reference voltage having a pulse height proportional to a voltage applied to the armature winding and an armature current and having a pulse width corresponding to a rotation speed of the rotor; and the induced voltage Magnetic pole position detection means for outputting a magnetic pole position detection signal by comparing the reference voltage with the interphase detection voltage corresponding to the potential difference between any two phases among the induced voltages of each phase detected by the detection means, and the magnetic pole. Control means for outputting an energization timing signal based on the position detection signal, and switching on / off of the switching element based on the energization timing signal controls the on / off switching of the armature winding of each phase. Brushless motor driving device comprising and an output circuit.