JP3416494B2 - DC brushless motor control device and DC brushless motor control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a DC brushless motor used in, for example, a compressor or a blower.

[0002]

2. Description of the Related Art FIG. 17 shows a conventional DC brushless motor.
It is a block diagram of the control apparatus of (it is hereafter abbreviated as DC-BLM).
In the figure, M1 is a DC-BL having windings U, V, W
It is M. MC1 is a microcomputer that outputs a predetermined control signal to the inverter according to the position detection signal output from the position detection circuit. TRup, TRun, TRv
p, TRvn, TRwp, and TRwn are switching elements that form an inverter, and are connected to and controlled by the microcomputer MC1. The position detection circuit includes resistors R1,
R2, Ru1, Ru2, Rv1, Rv2, Rw1, Rw
2 and the comparators CPu, CPv, CPw, and outputs a position detection signal by comparing the induced voltage generated in the windings U, V, W with the neutral point voltage obtained from the bus voltage of the inverter. There is a case where a rotor position sensor such as a Hall IC is attached to the motor M1 and the rotor position is obtained from this. However, for a motor used in an environment where it is difficult to attach the position sensor like a compressor motor. In this case, a control method that does not use the sensor as described above is often used.

FIG. 18 shows the waveform of each part of FIG. When the motor M1 is driven by 120 ° energization, no current flows through the phases during the time (section) in which the motor M1 is not energized, so that an induced voltage is generated in the winding at the terminal of the motor M1. This induced voltage is generated in a sine wave shape in synchronization with the relative position of the stator winding of the motor M1 and the permanent magnet of the rotor. The position detection circuit detects the timing of a point (hereinafter, referred to as a zero cross point) at which the induced voltage intersects the neutral point voltage with a comparator and outputs it as a position detection signal.

Based on this signal, the microcomputer MC1 obtains information on the rotational position of the rotor of the motor M1 and outputs a predetermined drive signal to the switching element of the inverter. This enables sensorless driving of the motor M1.

In the above DC-BLM control device and rotor position detecting method, since the section in which the phases are not energized has an electrical angle of 60 °, control is performed so that the zero cross point appears at the center of this section. Considering as a reference, the energization timing can be made variable within the range of 30 ° before and after.

On the other hand, when it is desired to increase the energization timing to 30 ° or more, for example, Japanese Patent Laid-Open No. 62-12.
In the brushless DC motor disclosed in Japanese Patent No. 3979,
As shown in FIG. 19, the comparator in the position detection circuit is provided with hysteresis so that it can be delayed by 30 ° or more. By giving the comparator a hysteresis characteristic, the same effect as that in which the potential of the virtual neutral point fluctuates up and down by the width of the hysteresis can be obtained.

As a result, as shown in FIG. 20, the position detection signal output from the position detection circuit includes a delay corresponding to the width of hysteresis with respect to the actual zero cross point. Therefore, it is possible to delay the original energization timing beyond the maximum value of 30 °.

Alternatively, the variable speed control of the DC-BLM is performed by P
When the WM control is used, the waveform of the induced voltage is a chopped waveform as shown in FIG. In this case, if the zero-cross point of the induced voltage appears in this chopping waveform, accurate position detection is possible, but if it does not appear in the waveform, the position detection signal will be delayed, and P will be the maximum.
It is delayed by the off time of the WM signal.

For example, in the drive device disclosed in Japanese Unexamined Patent Publication No. 8-182378, as shown in FIG. 22, a plurality of potentials at the virtual neutral point are set, and those voltages and induced voltages are compared by a comparator. Then, the result is input to the microcomputer. As a result, even if the zero-cross point of the actual induced voltage overlaps the OFF time of PWM, if a signal is detected in the comparator that compares with a different voltage in the ON time before that, by applying correction from that, Position detection error is kept small.

[0010]

DISCLOSURE OF THE INVENTION The above conventional DC-B
In the LM control device and the rotor position detecting method,
Since the electrical angle is 60 ° in the section where the phase is not energized, the energization timing is 30 times before and after considering the case where the zero cross point is controlled to come to the center of this section.
It can be varied in the range of °.

By the way, in the case of a DC-BLM using a rotor (hereinafter abbreviated as IPM rotor) having a structure in which a permanent magnet is embedded inside as shown in FIG. 23, the magnetic flux generated from the stator side is φd and φq. Since the d-axis and q-axis inductances Ld and Lq of the rotor differ depending on the presence or absence of a magnet in the path and have a reverse salient polarity (Ld <Lq), efficiency can be improved by using reluctance torque together. Also,
It is also possible to extend the operating range using field weakening control.

However, in order to effectively utilize the reluctance torque and perform the field weakening control, it is necessary to greatly advance the timing of energization. On the other hand, the above D
In the C-BLM drive system, since it is possible to advance only up to 30 °, the effects of reluctance torque and field weakening effect control cannot be sufficiently obtained.

The IPM rotor as shown in FIG. 23 has a structure in which magnets are arranged so as to concentrate the magnetic flux near the center of the pole, and the magnetic flux density near the center of the pole becomes nearly uniform, so that the induced voltage is increased. May become flat near the zero cross point. At this time, in the position detection method described above, the detection of the zero-cross point becomes unstable, which easily causes uneven rotation, noise, and vibration.

When the method disclosed in Japanese Patent Laid-Open No. 62-123979 is used, the energization timing can be delayed by 30 ° or more due to the hysteresis of the comparator, but conversely, it cannot be advanced by 30 ° or more. Is not suitable for use in reluctance torque and field weakening control.

Further, the method disclosed in Japanese Unexamined Patent Publication No. 8-182378 can suppress the delay in position detection by PWM control to be small, and the potential difference between a plurality of set virtual neutral point voltage and the neutral point. By making it larger, it is possible to advance or delay the energization timing by 30 ° or more. However, many comparators are required to compare each set voltage with the voltage of each phase of the motor, and many input ports of the microcomputer for processing those outputs by the microcomputer are also required, which reduces cost. Is disadvantageous to

The present invention has been made in order to solve the above-mentioned problems, and makes it possible to further advance the energization timing so that the effects of reluctance torque / field weakening control can be sufficiently obtained. An object of the present invention is to provide a drive device for a DC brushless motor, which can improve the rotor position detection accuracy at low cost.

[0017]

A controller for a DC brushless motor according to the present invention includes a DC brushless motor having a rotor and a multi-phase winding, and switching of energization for each winding of the DC brushless motor. An inverter that performs variable speed control by chopping, a position detection circuit that detects the position of the rotor from an induced voltage generated in each winding of a DC brushless motor, and an inverter that is controlled based on a signal output from this position detection circuit a microcomputer for, provided the position detection circuit, the inverter bus voltage or DC
Virtual neutral by voltage division from brushless motor terminal voltage
The resistance to get the point and the electric potential of the virtual neutral point by switching.
And a neutral point generation unit including a switching element that changes the position .

[0018]

Further, the medium of point generation unit is intended to operate so as to output the virtual neutral point at a timing earlier than the detection output signal from the position detection circuit of the zero-cross point of the induced voltage.

Further, the medium of point generation unit is intended to operate so that the output signal from the position detecting circuit outputs the virtual neutral point at a timing later than the detection of the zero-cross point of the induced voltage.

Further, a plurality of virtual neutral points are set only at a voltage lower than the actual neutral point or only at a high voltage, depending on the combination of resistance values.

In the DC brushless motor, the magnetic flux between the magnetic poles is small over a wide range, and the change amount of the virtual neutral point is small.

Further, one switching element is used in the position detection circuit, and two neutral point voltages are sequentially compared with respect to one zero cross point detection.

Further, a logic circuit for generating a signal for driving the switching element from the drive signal of the inverter is provided.

A DC brushless motor control method according to the present invention comprises a step of detecting a rotor position by comparing an induced voltage with a virtual neutral point in an inverter which controls a DC brushless motor at a variable speed, and a bus voltage of the inverter.
Or by dividing the terminal voltage of the DC brushless motor
The resistance to get the virtual neutral point and the virtual middle by switching
It is composed of a switching element that changes the potential of the sex point.
And a step of changing the virtual neutral point and advancing the detection timing of the zero cross point with the induced voltage to advance the control phase to perform the field weakening control.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings.
1 is a diagram showing a first embodiment of the present invention, which is a DC-B.
It is a block diagram of the drive device of LM. In the figure, M1 is a DC-BLM having windings U, V, W. Reference numeral 1 is an inverter that performs variable speed control by switching energization and chopping for each winding of the motor, and 2 is a position detection circuit that detects the position of the rotor from the induced voltage generated in the motor M1. The MC 1 is a microcomputer that controls each switching element of the inverter 1 based on the signal output from the position detection circuit 2.

The DC-BLM drive device comprises an inverter 1, a position detection circuit 2, and a microcomputer MC1. The inverter 1 is a switching element TRup, TR for controlling energization of the windings U, V, W of the motor M1.
It is composed of un, TRvp, TRvn, TRwp, and TRwn. The position detection circuit 2 includes resistors R1, R2 and R for obtaining a virtual neutral point by dividing the bus voltage of the inverter 1 by voltage division.
3, R4, switching elements TR1 and TR2 that change the potential of the virtual neutral point by switching, and resistors Ru1 and Ru that divide the terminal voltage of the winding (phase) of the motor.
2, Rv1, Rv2, Rw1, Rw2, and comparators CPu, CPv, CPw for comparing the virtual neutral point voltage with the divided terminal voltage of the winding.

The potential of the virtual neutral point fluctuates due to the operation of the switching elements TR1 and TR2, and the fluctuation width at this time is determined by the values of the resistors R1, R2, R3 and R4. In the case of the figure, three types of potentials are obtained by the operation of the switching elements TR1 and TR2, and when all two are turned off, the potential at the virtual neutral point becomes the highest.

Further, when TR1 is turned on, the potential becomes the lowest, and when only TR2 is turned on, an intermediate potential is taken. Here, when only TR2 is turned on, the potential of the normal neutral point is obtained, and the resistance value is selected such that the variation of the potential has the same width in the vertical direction with reference to this. Resistors Ru1 and R
u2, Rv1, Rv2, Rw1 and Rw2 are motors M1
This is for dividing the terminal voltage of the above into the operating range of the comparators CPu, Cpv, CPw.

FIG. 2 shows switching elements TR1 and TR2.
FIG. 6 is a diagram showing the operation of and the terminal voltage waveform of the motor M1.
As shown in the figure, in the conventional method of detecting the position by comparing the neutral point with the induced voltage generated in the terminal voltage, the energization phase can be advanced only up to 30 °. In the mode, by changing the virtual neutral point, it is possible to output the position detection signal at the position of the phase advanced from the conventional one, and it is possible to drive the energization phase more advanced than the conventional one.

FIG. 3 is a flow chart showing the operation of the DC-BLM drive device. In addition, FIG. 4 shows DC-B.
It is a figure which shows the example of the position detection circuit of the drive device of LM. The operation of the first embodiment will be described below with reference to FIG. There are six energization patterns of the inverter 1, which are sequentially switched according to the position of the rotor. Here, the six energization patterns are referred to as stages, and the operation will be described in order.

In stage 1, the U and V phases are energized.
Since the V and W phases are energized in the stage 6, TRwp is turned off and TRup is turned on in step a1. At the same time, TR1 is turned off. In stage 1, since the W phase is not energized, an induced voltage is generated in the terminal voltage. Since the induced voltage is generated so that it crosses from a high voltage to a low voltage with respect to the neutral point, the virtual neutral point is shifted to a high voltage, and the position detection signal is advanced in phase ahead of the actual zero cross point. To occur. When it is confirmed in step a2 that the output of the comparator CPw is off, the process proceeds to the next stage 2.

In stage 2, the U and W phases are energized.
In step a3, TRvn is turned off and TRwn is turned on. At the same time, TR1 is turned on. The induced voltage generated in the V phase that is not energized is generated so as to cross from the low voltage to the high voltage with respect to the neutral point. Therefore, the virtual neutral point is shifted to the low voltage and the position is advanced in the phase. Enable detection signal output. When it is confirmed in step a4 that the output of the comparator CPv is turned on, the process proceeds to stage 3.

By sequentially performing the same processing from the stage 3 to the stage 6, it is possible to drive in the energization phase which is more advanced than the conventional one.

As a result, the IPM motor can effectively utilize the reluctance torque,
More efficient operation becomes possible. In addition, field weakening control is also possible, enabling high speed rotation of the motor,
The operating range is expanded.

In FIG. 1, the virtual neutral point to be varied is obtained by dividing the bus voltage of the inverter 1. However, as shown in FIG. 4, the neutral point obtained from the terminal voltage of the motor M1 is divided. It is also possible to obtain by pressing.

Further, the switching element for changing the virtual neutral point is composed of two of TR1 and TR2, and the virtual neutral point is changed in three steps. However, as shown in FIG. 5, the switching element is changed. By setting the number to four, it is possible to set the virtual neutral point setting voltage in five steps.

Furthermore, by increasing the number of switching elements, the set voltage can be set in multiple stages. When trying to set the virtual neutral point in multiple stages, the switching elements are increased by the extension of FIG. 1 and FIG. 5 and the voltage dividing resistance is increased because n−1 switching elements are obtained in order to obtain the set voltage of n stages. Is required and is not a very efficient method. At this time, it is possible to reduce the number of switching elements by adopting a circuit configuration as shown in FIG.

Embodiment 2. Embodiment 2 of the present invention will be described below with reference to the drawings.
The configuration diagram of the DC-BLM showing the second embodiment is the same as the configuration diagram of the DC-BLM of the first embodiment. The operation of the switching element TR1 of the position detection circuit 2 is different from that of the first embodiment. FIG. 7 is a diagram showing the waveform of the terminal voltage of the winding when driving the motor M1 and the operation of the switching elements TR1 and TR2 at that time, and FIG. 8 is a flowchart showing the operation at this time.

The operation will be described below with reference to FIG. First, when the motor M1 is driven, the windings U and V are energized according to the position of the rotor. In step b1 of stage 1, the switching element TRwp is turned off and TRup is turned on. Since TRvn is previously turned on in the stage 6, the U and V phases are energized. At this time, TR1 is turned on at the same time. Since TR2 is always off, this causes the virtual neutral point to have a higher voltage than the neutral point. Since the W phase is not energized, an induced voltage appears. When it is confirmed that the output of the comparator CPw is turned off by comparing the induced voltage waveform with the virtual neutral point in b2, the electrical angle is 6 in b3.
After the time of 0 ° -α has passed, the processing is performed in b2 of stage 2.
Move to.

The electrical angle α at b3 is set to be longer than the time immediately after the energization of the phase until the phase current stops. Since no induced voltage is generated while the phase current is flowing, position detection is impossible during this time. Further, as shown in FIG. 6, since the terminal voltage is inverted with respect to the voltage at the time of the immediately preceding energization at this time, the output of the comparator is also inverted and an erroneous detection signal is output. In order to prevent a zero-cross point that should be really detected from entering during this erroneous detection, the timing of starting energization is set to be earlier than 60 ° after position detection by α.

The position detection signal output from CPw is W
Since the induced voltage of the phase changes from a low voltage to a high voltage, a comparison is made with a virtual neutral point voltage of a high voltage, so that the output is made at a timing later than the conventional position detection point.

Next, in stage 2, the U and W phases are energized. At b4, the switching element TRvn is turned off,
Turn on TRwn. At the same time, TR1 is turned off to set the virtual neutral point to a high voltage. After confirming that the output of the comparator CPv is turned on in b5, the process is moved to the stage 3 after the elapse of 60 ° -α in b6.

The DC-BLM is driven by sequentially performing the same processing from stage 3 to stage 6. A big difference from the first embodiment is the operation of the switching element TR1, and the switching elements TRup, TRun, TRvp,
With respect to the operation of TRvn, TRwp, TRwn, the operation in which ON and OFF are just inverted is taken.

That is, since the low voltage is set at the timing when the virtual neutral point is set to the high voltage and the high voltage is set at the timing when the low voltage is set in the first embodiment, the position detection from the comparator is performed. The output is output at a timing later than the zero-cross point of the actual induced voltage.

As a result, it becomes possible to drive with an energization phase delay of 30 ° or more, which was impossible with the conventional method.

Since it is possible to drive the energization phase with a large delay, the power factor during operation is greatly reduced. For this reason, a large amount of current flows in the motor in a low rotation and low torque state, and heat generation of the motor increases. When this method is used in the compressor motor of a room air conditioner,
The heat generation can be used to shorten the time for defrosting.

Embodiment 3. Embodiment 3 of the present invention will be described below with reference to the drawings.
The configuration diagram of the DC-BLM drive device shown in the third embodiment is similar to that of the drive device according to the first embodiment, but the combination of the values of the voltage dividing resistors R1, R2, R3, and R4 of the position detection circuit 2 is different. . By the operation of the switching elements TR1 and TR2, the voltage at the virtual neutral point changes to the voltage at the neutral point and a voltage higher or lower than that. The difference from the first embodiment is that the changing voltage is only a high voltage or a low voltage with respect to the neutral point voltage.

For example, when it is set so as to change only to a voltage lower than the neutral point voltage, the switching element TR
When both 1 and TR2 are off, the value of the resistance is set so that the virtual neutral point takes the voltage of the normal neutral point. By doing so, when the switching element TR2 is turned on, the virtual neutral point becomes a low voltage, and when the switching element TR1 is turned on, the virtual neutral point is set to a lower voltage.

On the contrary, when the neutral point is set to change only to a high voltage, the switching element TR1
When is turned on, the resistance value is set such that the virtual neutral point voltage becomes the normal neutral point voltage. As a result, when the switching element TR1 is turned off and TR2 is turned on, the virtual neutral point changes to a high voltage, and when both TR1 and TR2 are turned off, the virtual neutral point changes to a higher voltage.

FIG. 9 shows the drive voltage in the third embodiment. In this case, the voltage at the virtual neutral point is set only to a voltage lower than the neutral point voltage. In normal operation, the switching elements TR1 and TR2 are in the off state, and the virtual neutral point voltage is equal to the original neutral point voltage as shown in FIG. 9 (a). The phase angle of energization at this time is within 30 ° for both advance and delay.

Next, when it is desired to operate at a phase angle of 30 ° or more or around 30 °, the switching element TR2 is turned on. As a result, the voltage at the virtual neutral point becomes lower than the neutral point voltage as shown in FIG. 9B. At this time, the signal output from the position detection circuit has a lead phase where the induced voltage rises and a lag phase where the induced voltage falls. Since the operation is performed in the advanced phase, the operation is performed here based on the position detection signal at the rising portion of the induced voltage.

Further, when the operation is performed with the phase angle advanced, the switching element TR1 is turned on to change the voltage at the virtual neutral point to a lower voltage. As a result, as shown in FIG. 9C, the position detection signal is output at an earlier timing, and the operation can be performed with a larger lead phase.

On the other hand, when the operation is performed based on the position detection signal output at the falling portion of the induced voltage, the operation can be performed in the delayed phase. The same effect can be obtained by setting the voltage at the virtual neutral point to a voltage higher than the neutral point voltage. In this case, it should be noted that the operation of the switching element and the output timing of the position detection signal are different.

As described above, by setting a plurality of potentials at the virtual neutral point in the higher or lower direction with respect to the neutral point voltage, it becomes possible to finely set the phase angle of energization. As described in the effect of the first embodiment, by advancing the normal phase angle beyond the conventional value, it becomes possible to effectively utilize the reluctance torque and simultaneously control the field weakening in the IPM motor. However, the phase angle at which the field-weakening control effect is obtained is far ahead of the phase angle at which the maximum efficiency is obtained by using the reluctance torque, and to obtain both effects, the phase angle It is advantageous to be able to make detailed settings.

In the present embodiment, since the phase angle can be set finely, it is possible to perform both highly efficient operation by effective use of reluctance torque and expansion of the operating range by field weakening. . Further, in the first embodiment, if a plurality of virtual neutral point voltages are set and the phase angle is set finely, the number of voltage dividing resistors and switching elements must be increased, which is a cost disadvantage. Become. The third embodiment is advantageous in terms of cost because the phase angle can be set finely with a small number of elements.

Fourth Embodiment Embodiment 4 of the present invention will be described below with reference to the drawings.
The configuration of the DC-BLM drive device according to the fourth embodiment is as follows.
This is the same as the driving device according to the first embodiment, but the voltage dividing resistors R1 and R are arranged so that the change in the voltage at the virtual neutral point that changes due to the operation of the switching elements TR1 and TR2 is reduced.
The difference is that the values of 2, R3 and R4 are selected.

FIG. 10 is a diagram showing operation waveforms in the fourth embodiment. As shown in FIG. 10A, the change in the virtual neutral point voltage is smaller than that in the first embodiment. The flowchart showing the operation is the same as the flowchart of the first embodiment shown in FIG.

In the DC-BLM, a magnet may be embedded in the rotor for the purpose of concentrating the magnetic flux of the permanent magnet in order to improve the performance, but in this case, the magnetic flux density near the inversion of the rotor poles. Is smaller, the change in the magnetic flux that is linked to the entire winding becomes smaller when the magnetic flux generated from this portion during the rotation of the rotor begins to be linked to the winding of the stator, or when it is not linked. As a result, the generation of the induced voltage is reduced, and a flat portion is generated on the waveform near the zero cross. Therefore, the timing of outputting the position detection signal is likely to be unstable due to the influence of noise or the like, and DC-
This causes uneven rotation, vibration, and noise of the BLM.

On the other hand, the voltage of the virtual neutral point used in the position detection circuit is switched to a voltage above or below the neutral point voltage according to the drive pattern. As a result, FIG.
As shown in (b), the voltage comparison is avoided in the portion where the induced voltage is flat, and the voltage comparison is performed in the portion where the induced voltage has a relatively slope. In this way, the output timing of the position detection signal is stabilized. This makes it possible to stabilize the rotation of the DC-BLM and suppress the generation of vibration and noise. The change amount of the virtual neutral point voltage changed here is set to a voltage sufficient to obtain a sufficient gradient while avoiding the flat part of the induced voltage waveform.

Embodiment 5. Embodiment 5 of the present invention will be described below with reference to the drawings.
FIG. 11 is a configuration diagram of a DC-BLM drive device according to the fifth embodiment. Compared with the configuration of the first embodiment, the difference is that the number of switching elements that makes the virtual neutral point voltage variable is one.

By turning the switching element TR1 on and off, the virtual neutral point voltage is changed above and below the neutral point voltage. FIG. 12 is a diagram showing the waveform of the terminal voltage of the winding and the operation of the switching element TR1 when the motor M1 is driven, and FIG. 13 is a flowchart showing the operation at this time.

The operation will be described below with reference to FIG. First, when the motor M1 is driven, the windings U and V are energized according to the position of the rotor. In step C1 of stage 1, the switching element TRwp is turned off and TRup is turned on. Since TRvn was turned on in the previous stage 6,
The U and V phases are energized. At this time, TR1 is in the ON state, and the voltage of the virtual neutral point is lower than the neutral point voltage. Since the W phase is not energized, an induced voltage is generated.

In C2, when it is confirmed by comparison between the W-phase terminal voltage and the virtual neutral point that the output of the comparator CPw is turned off, TR1 is turned off in C3, and this time, the virtual neutral point. Set the voltage at the point to a voltage higher than the neutral point. At this point, the virtual neutral point voltage becomes higher than the induced voltage, so that the output of CPw is turned on.

Next, at C4, the induced voltage of the W phase and the virtual neutral point voltage are compared to confirm that CPw is turned off again. Then, the processing is moved to stage 2, and at C5, T
Rvn is turned off and TRwn is turned on.

Thereafter, the DC-BLM is driven by sequentially performing processing up to the stage 6. For example, the fourth embodiment
In this case, since the virtual neutral point voltage is changed up and down with respect to the neutral point voltage, the detected position signal has a phase lead or lag. This phase cannot be uniquely determined because the amplitude and waveform of the induced voltage differ depending on the rotation speed of the motor, the rotor shape, and the like. When operating at a constant speed, fluctuation does not occur between the generation of the position detection signal and the rotor position, but it is difficult to accurately grasp the phase angle of energization.

On the other hand, when the detection is performed twice for one position detection section, the actual zero-cross timing of the induced voltage occurs in the middle of the detection timing of the two position detection signals. The corner is easy to guess. As described above, the position detection accuracy is improved and the rotation can be stabilized.

Sixth Embodiment Embodiment 6 of the present invention will be described below with reference to the drawings.
FIG. 14 is a configuration diagram of a DC-BLM drive device according to the sixth embodiment. Compared with the configuration diagram of the fourth embodiment,
The difference is that there is a logic circuit that generates a signal for driving the switching element TR1. This logic circuit includes inverter drive signals TRup, TRun, TRvp, T.
Switching element TR from Rvn, TRwp, TRwn
Although the drive signal of 1 is generated, the configuration of this logic circuit differs depending on the speed control method of the inverter.

As in the fourth embodiment, TR from the microcomputer
Since it is not necessary to output the drive signal of 1, the effect equivalent to that of the fourth embodiment can be obtained only by adding the logic circuit. Therefore, it is not necessary to change the program of the microcomputer, and the application to the existing system becomes easy.

FIG. 15 is an example of a logic circuit. PWM
When the chopping operation is performed in all the switching elements of the inverter as in the front-back superposition method of FIG.
The drive signal of TR1 can be generated by using the logic circuit shown in (a). In addition, a method in which PWM is superimposed only on the lower side, that is, TRun, TRvn, TRw
When the chopping operation is performed only with n, FIG.
Signals can also be generated by the circuit shown in (b). T
Since chopping is not performed in Rup, TRvp, and TRwp, the circuit configuration is simplified by using these signals. When PAM is used for speed control,
Since the switching element of the inverter is not chopped, it is possible to generate a signal even by the circuit shown in FIG. 15C, which further simplifies the circuit configuration.

Further, by using the driving device having the structure shown in FIG. 16, it is possible to obtain the same effects as those of the first and second embodiments. The drive signal of the switching element TR1 that changes the virtual neutral point according to the drive of the motor is
The drive signal of the switching element TR2, which is generated from the drive signal of the inverter by the logic circuit and causes the virtual neutral point to coincide with the neutral point voltage, is output from the microcomputer.

The drive signal for the switching element TR2 is simultaneously output to the switching element TR1 to control the operation of the switching element TR1. During normal operation, the microcomputer outputs a signal for turning on the switching element TR2. Since this signal simultaneously outputs a signal for turning off the switching element TR1,
The neutral point voltage is set in the position detection circuit. next,
When operating with the energization phase greatly advanced or delayed, the microcomputer outputs a signal for turning off the switching element TR2. At this time, since a signal for turning on is output to TR1, the switching element TR1 operates according to the drive signal generated by the logic circuit.

In FIG. 16, the output from the microcomputer outputs only one signal for turning on and off TR2, and this output is used for switching whether to greatly advance or delay the energization phase during operation. Therefore, it is not always necessary to switch over according to the operation of the motor. Therefore, the load on the processing of the microcomputer is small and the change of the program is small.

As described above, by adopting the configuration shown in FIG. 14, it is possible to obtain the same effect as that of the fourth embodiment without changing the software of the microcomputer. Moreover, since the software of the microcomputer is not changed, it is possible to obtain the effect by slightly changing the circuit of the existing system.

Further, by adopting the configuration of FIG. 16, the change of the software of the microcomputer can be minimized and the load on the processing of the microcomputer at the time of operation can be minimized. The effect of 4 is obtained.

[0076]

The controller for a DC brushless motor according to the present invention includes a DC brushless motor having a rotor and a multi-phase winding, and a variable speed by switching energization and chopping for each winding of the DC brushless motor. An inverter for controlling, a position detection circuit for detecting the position of the rotor from the induced voltage generated in each winding of the DC brushless motor, a microcomputer for controlling the inverter based on the signal output from this position detection circuit, and a position Installed in the detection circuit, the bus voltage of the inverter or the DC brushless motor
A resistor that obtains a virtual neutral point by voltage division from the terminal voltage, and
A switch that changes the potential of the virtual neutral point by
Since the configuration is provided with the neutral point generating unit configured to change the virtual neutral point configured by the switching element, the number of components of the position detection circuit can be reduced.

Further, by operating the neutral point generator so that the output signal from the position detection circuit outputs the virtual neutral point at a timing earlier than the detection of the zero cross point of the induced voltage, the IPM motor has a reluctance. The torque can be effectively used, and more efficient operation becomes possible. In addition, field weakening control becomes possible, and the motor can rotate at high speed, and the operating range is expanded.

Further, the energization phase is increased by operating the neutral point generator so as to output the virtual neutral point at a timing when the output signal from the position detection circuit is later than the detection of the zero cross point of the induced voltage. Since it is possible to drive the vehicle with a delay, the power factor during operation is greatly reduced. For this reason, a large amount of current flows in the motor in a low rotation and low torque state, and heat generation of the motor increases. For example, if this method is used in a motor of a compressor of a room air conditioner, heat generation can be used to shorten the defrosting time.

Further, by setting a plurality of virtual neutral points only at a voltage lower than the actual neutral point or only at a higher voltage than the actual neutral point by combining the resistance values, the phase angle can be set finely, so that the reluctance torque can be set. It is possible to perform both high-efficiency operation by effective use of and the expansion of the operation range by field weakening.

In the DC brushless motor, the magnetic flux between the magnetic poles is small over a wide range, and the output timing of the position detection signal is stabilized by reducing the change amount of the virtual neutral point. This makes it possible to stabilize the rotation of the DC brushless motor and suppress the generation of vibration and noise.

Further, by using one switching element in the position detection circuit and sequentially comparing two neutral point voltages with respect to one zero-cross point detection, position detection accuracy is improved and rotation can be stabilized. It will be possible.

Further, since the logic circuit for generating the signal for driving the switching element from the drive signal of the inverter is provided, the load on the microcomputer is reduced, and the software of the microcomputer of the conventional drive device can be changed. Unnecessary or minimized.

The control method of the DC brushless motor according to the present invention comprises the step of detecting the position of the rotor by comparing the virtual neutral point and the induced voltage, and the bus voltage of the inverter or D.
Virtually divided by terminal voltage of C brushless motor
The resistance to get the neutral point and the virtual neutral point of the switching by the switching
Neutral composed of a switching element that changes the electric potential
By changing the virtual neutral point by the point generation unit and advancing the detection timing of the zero cross point with the induced voltage, the step of advancing the control phase and performing the field weakening control is provided, so that the reluctance torque is effective. Can be used for more efficient driving. In addition, field weakening control becomes possible, and the motor can rotate at high speed, and the operating range is expanded.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a DC-BLM drive device showing a first embodiment of the present invention.

FIG. 2 is a DC-BLM according to the first embodiment of the present invention.
FIG. 3 is a diagram showing operation waveforms of respective parts of the driving device of FIG.

FIG. 3 is a DC-BLM according to the first embodiment of the present invention.
6 is a flowchart showing the operation of the driving device of FIG.

FIG. 4 is a DC-BLM according to the first embodiment of the present invention.
It is a figure which shows the example of the position detection circuit of the drive device of FIG.

FIG. 5 is a DC-BLM according to the first embodiment of the present invention.
It is a figure which shows the example of the position detection circuit of the drive device of FIG.

FIG. 6 is a DC-BLM according to the first embodiment of the present invention.
It is a figure which shows the example of the position detection circuit of the drive device of FIG.

FIG. 7 is a DC-BLM according to the second embodiment of the present invention.
FIG. 3 is a diagram showing operation waveforms of respective parts of the driving device of FIG.

FIG. 8 is a DC-BLM according to the second embodiment of the present invention.
6 is a flowchart showing the operation of the driving device of FIG.

FIG. 9 is a DC-BLM according to the third embodiment of the present invention.
FIG. 3 is a diagram showing operation waveforms of respective parts of the driving device of FIG.

FIG. 10 is a DC-BL according to a fourth embodiment of the present invention.
It is a figure which shows each part operation waveform of the drive device of M.

FIG. 11 is a DC-BLM showing a fifth embodiment of the present invention.
It is a block diagram of the drive device of.

FIG. 12 is a DC-BL according to a fifth embodiment of the present invention.
It is a figure which shows each part operation waveform of the drive device of M.

FIG. 13 is a DC-BL according to a fifth embodiment of the present invention.
It is a flowchart figure which shows operation | movement of the drive device of M.

FIG. 14 is a DC-BLM showing a sixth embodiment of the present invention.
It is a block diagram of the drive device of.

FIG. 15 is a DC-BL according to a sixth embodiment of the present invention.
It is a figure which shows the logic circuit of the drive device of M.

FIG. 16 is a DC-BL according to a sixth embodiment of the present invention.
It is a figure which shows the example of a structure of the drive device of M.

FIG. 17 is a diagram showing a configuration of a conventional DC-BLM drive device.

FIG. 18 is a diagram showing operation waveforms of respective parts of a conventional DC-BLM drive device.

FIG. 19 is a diagram showing a configuration of a conventional DC-BLM drive device.

FIG. 20 is a diagram showing operation waveforms of respective parts of a conventional DC-BLM drive device.

FIG. 21 is a diagram showing operation waveforms of respective parts of a conventional DC-BLM drive device.

FIG. 22 is a diagram showing a configuration of a conventional DC-BLM drive device.

FIG. 23 is a diagram showing a structure of a DC-BLM rotor.

[Explanation of symbols]

1 inverter, 2 position detection circuit, CPu, CPv,
CPw comparator, MC1 microcomputer, M1 motor, R1, R2, R3, R4, Ru1, Ru2, Rv
1, Rv2, Rw1, Rw2 resistors, TRup, TRu
n, TRvp, TRvn, TRwp, TRwn, TR
1, TR2 switching element, U, V, W winding.

Continuation of front page (56) Reference JP-A-8-182378 (JP, A) JP-A-7-39188 (JP, A) JP-A-4-236192 (JP, A) JP-A-8-336269 (JP , A) JP-A-5-211796 (JP, A) JP-A-8-80083 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 6/18

Claims (8)

(57) [Claims] 1. A DC brushless motor having a rotor and a multi-phase winding, an inverter for performing variable speed control by switching energization and chopping for each winding of the DC brushless motor, and a DC brushless motor A position detection circuit that detects the position of the rotor from the induced voltage generated in each of the windings, a microcomputer that controls the inverter based on a signal output from the position detection circuit, and the position detection circuit , Bus of the inverter
Pressure or voltage divided from the DC brushless motor terminal voltage
Therefore, the resistance to obtain the virtual neutral point and the switching
It is composed of a switching element that changes the potential of the virtual neutral point.
And a neutral point generation unit that is formed.
C brushless motor controller. 2. A method before Symbol neutral point generator, wherein the output signal from the position detection circuit be operated so as to output the virtual neutral point at a timing earlier than the detection of the zero-cross point of the induced voltage controller of the DC brushless motor according to claim 1 Symbol mounting and. The 3. A front Symbol neutral point generator, characterized in that to operate so that the output signal from the position detecting circuit outputs the virtual neutral point at a timing later than the detection of the zero-cross point of the induced voltage controller of the DC brushless motor according to claim 1 Symbol mounting and. By wherein the combination of the resistor value, the virtual neutral point only to the actual lower voltage than the neutral point, or high DC brushless according to claim 1, wherein the plurality set only to a voltage Motor control device. Wherein said DC brushless motor intended magnetic flux between the magnetic poles is small extensive, DC of claim 1 Symbol mounting, characterized in that the said variation amount of the virtual neutral point slightly
Controller for brushless motor. 6. Using one said switching element to the position detection circuit, for one zero-cross point detection, claim 1, characterized in that sequentially compared to the two neutral point voltage
A controller for the DC brushless motor described. 7. A signal for driving the switching element, the control device of the DC brushless motor according to claim 1, further comprising a logical channel circuit for generating the driving signal of the inverter. 8. An inverter for variable speed control of a DC brushless motor, the step of detecting a rotor position by comparing a virtual neutral point with an induced voltage ;
From the bus voltage or the terminal voltage of the DC brushless motor
Resistance to get a virtual neutral point by voltage division and switching
Therefore, a switching element that changes the potential of the virtual neutral point
A step of changing the virtual neutral point and advancing the detection timing of the zero cross point with the induced voltage to advance the control phase to perform the field weakening control. D characterized by
C brushless motor control method.