JPH07264891A - Method and device for detecting position of rotor of motor - Google Patents

Abstract

PURPOSE:To reduce the number of rotor position detecting lines so that the exclusively used number of input ports of a microcomputer for controlling motor can be reduced and the input ports of the microcomputer can be utilized effectively. CONSTITUTION:When the energization of three armature windings of a three-phase brushless motor 1 is switched based on the detected position of a rotor, first and second switching sections 10 and 11 fetch the partial voltage waveforms (voltage waveforms including the information at the virtual neutral point (a) of the induction voltage of the motor) of terminal voltages of the three windings, but the sections 10 and 11 fetch the partial terminal voltages (voltage waveforms including the information at the virtual neutral point of the induction voltage) in different two phases due to a control signal from a control section 13. The sections 10 and 11, in addition, fetch the voltage waveforms including the information of the virtual neutral points of the induction voltage in each phase and input the signals of the fetched voltage waveforms to a virtual neutral point detecting section 12 so as to obtain the virtual neutral point in each phase in one signal. The obtained signal of the virtual neutral points is inputted to a microcomputer 14 so as to detect the position of the rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor used in an air conditioner (for example, a sensorless DC brushless motor).
The present invention relates to a rotor position detecting technique, and more particularly, to a rotor position detecting method and apparatus for a brushless motor that reduces the number of lines required for detecting the rotor position and occupies the number of input ports of a microcomputer. It is a thing.

[0002]

2. Description of the Related Art In controlling the rotation of a sensorless DC brushless motor (hereinafter referred to as a brushless motor),
For example, in the case of a three-phase brushless motor, the control device shown in FIG. 3 is conventionally used.

In FIG. 1, this control device comprises a drive unit 2 for switching and applying a DC power supply Vcc to a plurality of armature windings of a brushless motor 1, and a brushless motor 1.
Terminal voltage (shown in FIGS. 4A, 4B, and 4C); 12
A virtual neutral point detection unit 3 that detects a virtual neutral point (a shown in FIG. 4) by comparing U, V, W with voltages having different phases of 0 degrees; A drive signal that outputs a drive signal of the drive unit 2 for predetermined switching of energization of each armature winding based on position detection timing with the virtual neutral point a being a predetermined phase delay (for example, π / 6 phase delay) And a creation unit 4.

A microcomputer 5 is generally used as the drive signal generator 4, and the signal from the virtual neutral point detector 3 is input to the input port of the macro computer 5.

In the control device having the above-described structure, the microcomputer 5 drives the drive unit 2 when the brushless motor 1 is activated.
The drive signal for turning on and off the transistor of (1) is output in a predetermined manner to switch the energization of each armature winding of the brushless motor 1, and the brushless motor 1 is synchronously operated for a predetermined time.

After a lapse of a predetermined time, the synchronous operation is switched to the operation based on the position detection. At this time, the microcomputer 5 detects the position of the rotor of the brushless motor 1 by three signals from the virtual neutral point detecting section 3. . Then, based on the position detection, the transistor of the drive unit 2 is driven on and off in a predetermined manner to switch the energization of each armature winding, thereby controlling the rotation of the brushless motor 1. That is, the output signal from the virtual neutral point detection unit 3 becomes normal during the synchronous operation.

In the virtual neutral point detector 3,
The detected virtual neutral point a is a predetermined phase (for example, π / 6 phase)
Alternatively, the signal of this phase delay may be input to the microcomputer 5 as position detection. In this case, the microcomputer 5 does not have a function of measuring the predetermined phase, but drives the transistor of the drive unit 2 to turn on and off in a predetermined manner based on the input signal (position detection signal) to drive each armature winding. It will switch the energization of the wire.

[0008]

By the way, in the above brushless motor control device, in the case of the three-phase brushless motor 1, three virtual neutral points a are generated by the three-phase terminal voltages.
Is detected and the signals of these three virtual neutral points a are input to the input port of the microcomputer 5 to detect the position of the rotor, the three input ports of the microcomputer 5 must be occupied. In addition, the effective use of the input port of the microcomputer 5 is hindered.

Further, when there are sufficient input ports of the microcomputer 5, no problem occurs. However, when a control microcomputer such as an air conditioner is used, the number of input ports of the microcomputer is too large. In some cases, for example, other functions may be reduced and allocated for the position detection. In particular, in the case of a microcomputer having a small number of input ports, this is a fatal drawback.

The present invention has been made in view of the above problems, and an object thereof is to reduce the number of lines for detecting the position of a rotor of a motor, which in turn occupies the number of input ports of a microcomputer used for motor control. It is an object of the present invention to provide a method and apparatus for detecting a rotor position of a motor, which is capable of effectively using the input port of the same microcomputer while reducing the number of inputs.

[0011]

In order to achieve the above object, according to the present invention, at least when the position of the rotor of the motor is detected in order to switch the energization of a plurality of armature windings of the motor, In order to extract the partial voltage waveform of the terminal voltage of each armature winding of, the terminal voltage of each armature winding is switched by a plurality of switching means, and the information of the virtual neutral point of the induced voltage is included in the terminal voltage. The partial voltage waveforms are sequentially extracted, the virtual neutral point of the extracted partial voltage waveforms of the respective phases is obtained as one signal, and the position of the rotor is determined based on the timing of the obtained virtual neutral point. The gist is to detect the.

[0012]

According to the above construction, for example, in the case of a three-phase brushless motor, the terminal voltages (voltages having 120-degree different phases) of the armature windings of the brushless motor have the first and second switching means (two In the first and second switching means, the terminal voltage of each phase is switched every 240 degrees of the phase of the terminal voltage based on the timing of the drive signal of the motor. Moreover, the first switching means and the second switching means are shifted by 120 degrees in phase, and the partial voltage waveforms of the virtual neutral points of the induced voltages of different phases are taken out, whereby the terminal voltage of each phase is obtained. A partial voltage waveform including a virtual neutral point of all induced voltages is extracted.

This partial voltage waveform is compared with a predetermined reference voltage, a virtual neutral point of the induced voltage of each phase is detected, and the signal of the detected virtual neutral point is input to the input port of the control microcomputer of the brushless motor. Is entered. Then, in the microcomputer, the position of the rotor is detected based on the virtual neutral point, and the drive transistor that drives the brushless motor is turned on based on this position detection,
The timing of the drive signal to turn off can be obtained. Therefore, only one input port of the microcomputer is required for detecting the rotor position.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless motor rotor position detecting method and apparatus according to the present invention is, for example, a three-phase sensorless DC.
Brushless motor (hereinafter referred to as brushless motor) 3
When the energization of one armature winding is switched based on the rotor position detection of the same brushless motor, the terminal voltages (induced voltages) of the three armature windings are sequentially switched by a plurality of switching means,
Further, the terminal voltages of different phases are sequentially switched by the respective switching means, and the partial terminal voltages of the respective phases (voltage waveforms including information on the virtual neutral point of the induced voltage) are sequentially taken out, and the taken-out partial terminals of different phases are taken out. The virtual neutral point of the induced voltage of each phase is obtained as one signal by the voltage waveform, and the position of the rotor is detected based on the obtained signal of the virtual neutral point.

Therefore, the controller of the brushless motor of the present invention has, for example, the configuration shown in FIG. In the figure, the same parts as those in FIG. 3 are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 1, for example, this control device inputs terminal voltages (voltages 120 degrees out of phase; induced voltages) U, V, W of three armature windings of a three-phase brushless motor 1 and outputs them. A first switching unit 10 that sequentially switches the terminal voltages U, V, and W to extract one partial terminal voltage;
Similarly, the terminal voltages U, V, W are sequentially switched.
A second switching unit 11 for extracting one partial terminal voltage different from the terminal voltage switched by the switching unit 10 of
In addition to the function of the virtual neutral point detection unit 12 that detects the virtual neutral point a of the induced voltage of each phase included in one signal and the microcomputer 5 shown in FIG. A control circuit (microcomputer) having a control unit 13 that outputs a control signal for controlling the first and second switching units 10 and 11 at signal timing.
14 and.

If the virtual neutral point detecting section 3 does not have a function of delaying the virtual neutral point a by a predetermined phase (for example, π / 6 phase), the microcomputer 14 determines that the virtual neutral point detecting section 3 is a virtual neutral point detecting section. 3 has a phase (π / 6) measuring unit 15 for detecting a π / 6 phase delay of the output signal from the signal No. 3 of FIG.
In addition to the function of the drive signal creation unit 4 shown in FIG. 1, the control unit 13 includes a drive signal creation unit 16 that outputs timing information of the drive signal.

Further, the first and second switching units 10 and 11
Represents the terminal voltages U, V, and
The switches are switches that sequentially switch W (for example, FET switches, etc.), and each switch has three force terminals and one output terminal.

The operation of the rotor position detecting method applied to the brushless motor controller will be described in detail with reference to the time chart of FIG.

First, when the brushless motor 1 is started up, the microcomputer 14 outputs a drive signal in order to operate the brushless motor 1 synchronously to turn on and off a plurality of transistors of the drive unit 2 in a predetermined manner, and a DC power source is supplied. Vc
c is switched and applied to each armature winding of the brushless motor 1, and the energization of each armature winding is sequentially switched.

After the synchronous operation has been performed for a predetermined time, the microcomputer 14 switches the DC power supply Vcc based on the position detection of the rotor of the brushless motor 1 and applies it to each armature winding. The energization is switched sequentially.

When switching to the operation based on the position detection, the terminal voltages U, V and W of the armature windings of the brushless motor 1 are applied to the first and second switching sections 10 and 11 (for example, as shown in FIG. (Shown in (c)) is input, and the first and second switching units 10 and 11 select one of the terminal voltages U, V, and W according to the control signal (timing of the drive signal) from the control unit 13. In order to take out, each switch is turned on and off in a predetermined manner.

More specifically, in the first switching section 10, as is apparent from FIG. 2D, the switches are sequentially switched at every 240 degrees of the phase of the terminal voltage, and the second switching section 1
In FIG. 1, as is clear from FIG. 2 (f), the switches are sequentially switched every phase 240 degrees with a phase delay of 120 degrees from the switching timing of the first switching unit 10.

By inputting timing information of a drive signal for turning on and off a transistor of the drive unit 2 to the control unit 13 in a predetermined manner, the first and second switching units 10 and 11 can be operated as shown in FIG.
As shown in (d) and (f), it is possible to switch to the side of the predetermined terminal voltage.

For example, when the first switching unit 10 is switched to the terminal voltage U side, the second switching unit 11 is switched to the terminal voltage W side during the first half 120 degrees, and the latter half 120 °.
The second switching unit 11 is switched to the terminal voltage V side during the interval.

When the first switching unit 10 is switched to the terminal voltage W side, the second switching unit 11 is switched to the terminal voltage V side during the first half 120 degrees, and during the latter half 120 degrees. Switches the second switching unit 11 to the terminal voltage U side.

Further, when the first switching unit 10 is switched to the terminal voltage V side, the second switching unit 11 is switched to the terminal voltage U side during the first half 120 degrees, and the latter half 120 °.
The second switching unit 11 is switched to the terminal voltage W side during the interval.

That is, the first and second switching units 10,
Partial voltages of the terminal voltages U, V, W are extracted by 11 and, as is clear from FIGS. 2 (e) and 2 (g), information on the virtual neutral point a of the induced voltage of each phase is included. All of the partial voltage waveforms are retrieved.

Output signals S1 and S2 of the first and second switching units 10 and 11 (voltage waveform including information on the virtual neutral point a)
Is inputted to the virtual neutral point detection unit 12, and the virtual neutral point detection unit 12 uses the input signals S1 and S2 as continuous signals, respectively, and compares them with a predetermined reference voltage as in the conventional case to induce each phase. The virtual neutral point a of the voltage is detected to obtain one signal, and the detection signal of the virtual neutral point a is output to the input port of the microcomputer 14.

In the virtual neutral point detector 12,
It is also possible to add the input signals S1 and S2 and compare the added signal with a predetermined reference voltage to detect the virtual neutral point a of the induced voltage of each phase and obtain one signal.

The microcomputer 14 measures the detection signal of the input virtual neutral point a by the induced voltage with the phase π / 6 delay by the phase measuring section 15, and creates the drive signal with the measured π / 6 phase delay timing. The timing of the drive signal for inputting to the unit 16 and turning on / off the transistor of the drive unit 2 in a predetermined manner to switch the energization of each armature winding is obtained. Then, when the brushless motor 1 is switched from the synchronous operation to the operation based on the position detection, the transistor of the drive unit 2 is turned on and off in a predetermined manner based on the timing obtained above, and the energization of each armature winding is switched. .

Further, while the operation is continued by the subsequent position detection,
The microcomputer 14 detects the position of the rotor by the detection signal of one virtual neutral point a input through the input port, and based on this position detection, outputs a drive signal for turning on and off the transistor of the drive 2 in a predetermined manner. Output.

As described above, only one line is required for detecting the position of the rotor based on the terminal voltages U, V, W of each armature winding of the brushless motor 1, that is, the input port of the microcomputer 14. The number of occupies is only one, and the position of the rotor can be detected with the same accuracy as the conventional one.

Therefore, the input port of the microcomputer 14 can be effectively used, the function does not need to be reduced when the microcomputer is used as a control device for an air conditioner, and the degree of freedom in selecting the microcomputer is reduced. growing.

The virtual neutral point detecting section 12 can be realized by the function of the microcomputer 14. In this case, two input ports are required for the microcomputer 14, but this also reduces the number of input ports by one as compared with the conventional case where three input ports are required. Therefore, the same effect as the above embodiment can be obtained. To be

[0036]

As described above, according to the motor of the present invention, when the energization of the plurality of armature windings of the motor is switched based on the position detection of the rotor of the brushless motor,
The terminal voltage (induced voltage) of each armature winding is sequentially switched by a plurality of switching means, but partial terminal voltages of different phases (voltage waveform including information of virtual neutral point of induced voltage) are taken out,
Further, a voltage waveform including information on the virtual neutral point of the induced voltage of each phase is extracted, the virtual neutral point of each phase is obtained by one signal by the signal of the extracted voltage waveform, and the obtained one signal Since the virtual neutral point of the induced voltage of each phase is detected by the above, it is possible to reduce the number of occupied input ports of the motor control microcomputer that detects the position of the rotor based on the virtual neutral point. Therefore, there is a useful effect that the input port of the microcomputer can be effectively used and that the degree of freedom in selecting a microcomputer for control is large when applied to an air conditioner or the like.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a controller to which a rotor position detecting method for a brushless motor is applied according to an embodiment of the present invention.

FIG. 2 is a schematic time chart diagram for explaining the operation of the controller for the brushless motor shown in FIG.

FIG. 3 is a schematic block diagram of a conventional brushless motor control device.

FIG. 4 is a schematic time chart diagram for explaining the operation of the control device shown in FIG.

[Explanation of symbols]

1 Brushless Motor (Sensorless DC Brushless Motor) 2 Drive Unit 3,12 Virtual Neutral Point Detection Unit 4,16 Drive Signal Generation Unit 5,14 Control Circuit (Microcomputer) 10 First Switching Unit 11 Second Switching Unit 13 Control unit 15 Phase measuring unit a Virtual neutral point U, V, W Terminal voltage of armature winding

Claims (3)

[Claims] 1. A motor rotor position detecting method for detecting the position of a rotor of a motor for switching energization of a plurality of armature windings of the motor, comprising: at least a terminal voltage of each armature winding of the motor. In order to extract the partial voltage waveform of, the terminal voltage of each armature winding is switched by a plurality of switching means, and the partial voltage waveform including the information of the virtual neutral point of the induced voltage of the terminal voltage is sequentially extracted, The virtual neutral point of the extracted partial voltage waveform of each phase is obtained as one signal, and the position of the rotor is detected based on the timing of the obtained virtual neutral point. And method for detecting rotor position of motor. 2. A motor rotor position detecting device for detecting the position of the rotor of the motor for switching the energization of a plurality of armature windings of the motor, wherein the terminal voltage of each armature winding of the motor is In order to extract a partial voltage waveform that includes information on the virtual neutral point of the induced voltage among at least the input terminal voltages that are input, turn on and off the input terminal voltages with a plurality of switch means. , A plurality of switching means for switching and outputting terminal voltages of different phases at timings of drive signals for driving the motor, and a virtual neutral point of the induced voltage of each phase by the switched partial voltage waveforms. A virtual neutral point detecting means for detecting and outputting as one signal, and the position of the rotor is detected based on the timing of the output signal of the virtual neutral point detecting means. Motor rotor position detecting apparatus according to. 3. A motor rotor position detecting device for detecting the position of the rotor of a brushless motor for switching the energization of three armature windings of the three-phase brushless motor, wherein each armature of the brushless motor is Input the terminal voltage of the winding, and at least extract the partial voltage waveform including the information of the virtual neutral point of the induced voltage among the input terminal voltages, and input the input terminal voltage to the specified phase angle. First switching means for switching for each one to output one partial voltage waveform, and terminal voltage of each armature winding of the brushless motor are input, and at least virtual induced voltage among the input terminal voltages is input. In order to extract the partial voltage waveform including the information of the neutral point, the input terminal voltages are switched at predetermined phase angles, and the switching timing of the first switching means and the predetermined phase delay. The second switching means for outputting one partial voltage waveform by switching at different timings, and the virtual neutral point of the induced voltage of each phase by the partial voltage waveforms switched by the first and second switching means. A virtual neutral point detecting means for detecting and outputting as one signal, and the position of the rotor is detected based on the timing of the output signal of the virtual neutral point detecting means. Motor rotor position detector.