JPH07322679A - Method for detecting position of rotor of brushless motor - Google Patents

Abstract

PURPOSE:To make it possible to decrease the number of the parts of the position detecting circuit of a rotor and to make it possible to decrease the number of the lines of position detecting signals. CONSTITUTION:This is the method for detecting the position of the rotor of a brushless motor for detecting the position of the rotor of the three-phase brushless motor. When the conduction of the armature winding of the brushless motor 1 is switched on the basis of the position detection of the rotor 1a of the brushless motor 1, the terminal voltage of the armature winding of the brushless motor l is inputted into a position detecting part 7, and two position detecting signals are obtained. The two position detecting signals are inputted into a control circuit 8. The control circuit 8 detects the rising and falling edges of the two position detecting signals, measures the time between the edges and estimates the other position detecting signal on the basis of the measured time and the edge timing of the position detecting signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor position detection technique for a sensorless DC brushless motor used in a motor of an air conditioner, and more particularly, to reduce the number of lines required for rotor position detection. The present invention relates to a rotor position detection method for a brushless motor that simplifies the circuit configuration for position detection.

[0002]

2. Description of the Related Art In order to control the rotation of this sensorless DC brushless motor (hereinafter referred to as brushless motor),
For example, in the case of a three-phase brushless motor, for example, the control device shown in FIG. 6 is required.

In FIG. 6, this control device includes an inverter section 2 for switching and applying a DC power supply to a plurality of armature windings of a brushless motor 1, and a brushless motor 1.
Terminal voltage (voltage with a phase difference of 120 degrees; induced voltage)
The position detection unit 3 that detects the position of the rotor 1a based on U, V, and W, and the energization of each armature winding of the brushless motor 1 are switched in a predetermined manner, and the position detection signal from the position detection unit 3 is also output. A control circuit (microcomputer) that outputs a control signal for the inverter unit 2 to switch each armature winding to a predetermined value while outputting a chopping signal that chops the predetermined control signal at a predetermined frequency among the control signals. In the control device having the above-described structure, a chopping unit 5 for chopping and outputting the control signal, and a driver unit 6 for driving the switch means of the inverter unit 2 by the control signal including the chopped signal. When the brushless motor 1 is started, the brushless motor 1 is synchronously operated for a predetermined time. Controls the rotation of the same brushless motor 1 based on the position detection signal of the rotor 1a of the motor 1 (switching to the position sensing operation).

By performing the synchronous operation of the brushless motor 1 for a predetermined time, as shown in FIG.
At each armature winding U, V, W of the brushless motor 1
Position detection signals A1, B1, C1 of the rotor 1a based on
Is obtained. In the figure, a is a spike voltage. Further, various circuits have been proposed as the position detecting unit 3 that outputs the position detection signals A1, B1, C1, and therefore the description of the circuits will be omitted.

In the control circuit 4, the position detection signal A
The energization of each armature winding of the brushless motor 1 can be switched based on 1, B1, C1 to control the rotation of the brushless motor 1, that is, the synchronous operation can be switched to the operation by position detection. That is, the output position detection signals A1, B1, C1 from the position detection unit 3 become normal during the synchronous operation.

[0006]

However, in the rotor position detection in the brushless motor control device, in the case of the three-phase brushless motor 1, three position detection signals A1, B1, C1 are obtained from the three-phase terminal voltages. Therefore, the circuit components are complicated, that is, the number of circuit components is large, the cost is high, and the position detection signals A1 and B are
Since 1 and C1 are 3 lines, there is a drawback that the number of wiring steps is large.

The present invention has been made in view of the above problems, and an object thereof is to simplify a circuit for detecting the position of a rotor of a brushless motor, that is, to reduce the number of parts and reduce cost. It is an object of the present invention to provide a rotor position detecting method for a brushless motor, which is capable of reducing the number of detection signal lines and reducing the number of wiring steps.

[0008]

In order to achieve the above object, a method for detecting a rotor position of a brushless motor according to the present invention relates to energizing a plurality of armature windings of the brushless motor to determine the position of the rotor of the brushless motor. When switching based on the detection signal, at least one position detection signal is obtained based on the terminal voltages of the plurality of armature windings of the brushless motor, while the timing of the remaining position detection signal is obtained by the obtained position detection signal. The gist is that the estimation is performed based on the time between the edges and the timing of the same position detection signal.

[0009]

With the above means, for example, in the case of a three-phase brushless motor, two or one position detection signal can be obtained based on the terminal voltage of each armature winding of the brushless motor (voltages different in phase by 120 degrees). To be The timing of the rising edge and falling edge of this position detection signal is detected, and the rising edge and falling edge of the remaining position detection signal, that is, the energization switching timing of the winding current is estimated based on the measurement time between these timings. To be done.

With this, since the timings of the three position detection signals are obtained, it is possible to switch the energization of each armature winding of the brushless motor, and therefore the brushless motor controls the rotation based on the position detection of the rotor. Will be done.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless motor rotor position detecting method according to the present invention switches energization of a plurality of armature windings of a sensorless DC brushless motor (hereinafter referred to as a brushless motor) based on rotor position detection of the brushless motor. At this time, at least one position detection signal is obtained based on the terminal voltages of a plurality of armature windings of the brushless motor, the rising and falling edges of the obtained position detection signal are detected, and the time between these edges is measured. At the same time, another position detection signal is estimated based on this measurement time and the timing of the edge of the position detection signal.

Therefore, the controller of the brushless motor according to the present invention has the structure shown in FIG. 1, for example. In the figure, the same parts as those in FIG. 6 are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 1, this control apparatus inputs two terminal voltages (voltages having 120 degrees different phases; induced voltages) U, V, W of the armature winding of the three-phase brushless motor 1 to detect two positions. A position detection unit 7 that outputs a signal and a control circuit (microcomputer) 8 that estimates the timing of another position detection signal based on the two position detection signals are provided.

Although the position detecting section 7 has a known circuit configuration, the number of components in the circuit configuration is reduced because only two position detection signals need to be obtained. The control circuit 8 also has the function of the control circuit 4 shown in FIG.

The operation of the rotor position detecting method applied to the brushless motor controller will be described below with reference to the time chart of FIG. 2 and the flowchart of FIG.

First, when the brushless motor 1 is started, the control circuit 8 outputs a control signal for synchronously operating the brushless motor 1 to turn on and off a plurality of switching elements of the inverter unit 2 in a predetermined manner, and the DC power supply Vcc. Is applied to each armature winding of the brushless motor 1 to sequentially switch the energization of each armature winding.

After the synchronous operation has been performed for a predetermined time, the control circuit 8 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 the operation is switched to the position detection, the terminal voltage U, for example, of each armature winding of the brushless motor 1 is input to the position detection section 7. The position detection section 7 performs the same process as the conventional one. Position detection signals A2, B
2 is output (shown in FIGS. 2D and 2E). The position detection signals A2 and B2 are shown in FIGS.
The position detection signals A1 and B1 shown in FIG.

Further, the control circuit 8 executes the synchronous operation of the brushless motor 1 while the input position detection signals A2 and B2 are supplied.
Based on the above, the timing of the remaining position detection signal C2 shown in FIG. 2 (f) is estimated.

Specifically, for example, when the control circuit 8 detects a rising edge (or a falling edge) of the position detection signal B2 (step ST1), it starts an internal timer (step ST2).

Then, when the falling edge (or rising edge) of the position detection signal A2 is detected (step ST3), the time of the internal timer is taken into consideration and the position detection signal A2 falls from the rising edge of the position detection signal B2. A predetermined time Ton (Ta1; shown in FIG. 2 (e)) is measured (step ST4), or a predetermined time Ton (Ta2; FIG. 2 (e) from the fall of the position detection signal B2 to the rise of the position detection signal A2. )) Is measured. At the same time, that is, the position detection signal A
Start the internal timer on the rising (or falling) edge of 2.

Subsequently, when the measured predetermined time Ta1 (or predetermined time Ta2) has elapsed (step ST
5), the predetermined time Ta1 (or the predetermined time Ta2)
When the time point a1 or a2 (arrow shown in FIG. 2 (f)) has elapsed is determined to be the rising edge or the falling edge of the remaining position detection signal C2, the winding current is switched (step ST6).

By repeating the above operation, the remaining position detection signal C2 shown by the broken-line rectangular wave in FIG. 2 (f) can be obtained based on the input position detection signals A2 and B2, and the control circuit 8 inputs the position detection signal. The energization of each armature winding can be switched according to the timing of A2, B2 and the estimated position detection signal C2.

As described above, the position detecting section 7 only needs to output two position detecting signals, and the winding voltage to be used is only two. In addition, by executing the control circuit 8, that is, by software. Since only the processing is required, the hardware circuit of the position detection unit 7 can be configured with a small number of parts, and the number of lines of the position detection signal can be reduced.

By the way, in the above embodiment, the measurement time between the rising edge and the falling edge of the input position detection signals A2 and B2 is used as the timing of the direct position detection signal C2. That is, the edge of the position signal immediately before observing the energization switching timing of the winding current is used, but before the rotor 1a of the brushless motor 1 rotates one half (half cycle) or one rotation (one cycle) before. The time data may be used to detect the current position of the rotor 1a.

The time data is the data between the timings of the position detection signals A2, B2, C2,
This data is stored in the internal memory of the control circuit 8 for only a half cycle or one cycle.

In this case, when the brushless motor 1 is used as a compressor motor of an air conditioner, for example, if the rotor 1a of the brushless motor 1 has two poles, a series of operations such as suction, compression, discharge, etc. are performed every cycle. If the rotor 1a of the brushless motor 1 has four poles, the series of operations is performed every half cycle, and the load fluctuates during the series of operations.

However, even in the current state of the brushless motor 1, for example, the timing of the compressed state or the discharged state, based on the position detection in the same state (the timing obtained in the compressed state or the discharged state) half cycle or one cycle before. The energization of each armature winding of the brushless motor 1 is switched.

As described above, by detecting the position of the rotor 1a in the current state of the brushless motor 1 by using the data of a half cycle or one cycle before, the actual position detection signal of the rotor 1a is obtained. Of each armature winding of the brushless motor 1 can be switched according to the load fluctuation of the brushless motor 1, that is, the brushless motor 1 can respond to the load fluctuation immediately.
The rotation of the brushless motor 1 can be controlled, and the smooth operation of the brushless motor 1 can be achieved.

4 and 5 are schematic flow charts for explaining another embodiment of the present invention. In addition,
See FIG. 1 for the controller of the brushless motor 1 in this embodiment.

This embodiment will be described with reference to the time chart of FIG. 2 and the flow charts of FIGS. 4 and 5.
In FIG. 2, the position detection signals A3 and B3 correspond to the position detection signals A2 and B2 shown in FIGS.

First, as described in the previous embodiment, the control circuit 8 is assumed to be in synchronous operation when the brushless motor 1 is started and switched to operation by position detection after a lapse of a predetermined time.

In this case, the control circuit 8 executes the synchronous operation of the brushless motor 1 while the input position detection signal A3
The timing of the remaining position detection signal C3 is estimated based on B3.

Specifically, the control circuit 8 controls the position detection signal A
When the rising edge of 3 is detected (step ST1
0), start the internal timer (step ST1)
1).

Subsequently, when the rising edge of the position detection signal B3 is detected (step ST12), the predetermined time ton from the rising of the position detection signal A3 to the rising of the position detection signal B3 is taken into consideration by taking the time of the internal timer into consideration.
(Tb1; shown in FIG. 6D) is measured (step S
T13). A calculation for halving the measured time ton is executed (step ST14) to calculate a predetermined time tb1 / 2.

Then, when the falling edge of the position detection signal A3 is detected (step ST15), the internal timer is started (step ST16).

When the falling edge of the position detection signal B3 is detected (step ST17), the predetermined time ton (tb2) from the fall of the position detection signal A3 to the fall of the position detection signal A3 is taken into consideration, taking the time of the internal timer into consideration. ;
(Shown in FIG. 7D) is measured (step ST18).
A calculation for halving the measured time ton is executed (step ST19) to calculate a predetermined time tb2 / 2.

Then, when the next rising edge of the position detection signal A3 is detected (step ST20), a timer for a predetermined time tb1 / 2 is started (step ST2).
1). At the same time, as described above, by detecting the rising edge of the position detection signal, the internal timer is started and the time ton from the rising edge of the position detection signal A3 to the rising edge of the position detection signal B3 is measured.

Subsequently, when the timer of the predetermined time tb1 / 2 times up (step ST22), the remaining position detection signal C3 is detected at the time point b1 (arrow shown in FIG. 2 (i)) when the predetermined time tb1 has elapsed. Judging that it is a rising edge, switching of the winding current is performed (step ST
23).

Then, when the next falling edge of the position detection signal A3 is detected (step ST24), a timer for a predetermined time tb2 / 2 is started (step ST2).
5). At the same time, as described above, by detecting the falling edge of the position detection signal, the internal timer is started and the time ton from the falling edge of the position detection signal A3 to the falling edge of the position detection signal B3 is changed. taking measurement.

Subsequently, when the timer for the predetermined time tb2 / 2 times out (step ST26), the remaining position detection signal C3 is detected at the time point b2 (arrow shown in FIG. 2 (i)) when the predetermined time tb2 elapses. It is determined to be the falling edge, and energization switching of the winding current is performed (step ST27).

By repeating the above operation, the same timing (switching timing of the winding current) as the remaining position detection signal C3 shown by the broken-line rectangular wave in FIG. 2I is obtained based on the input position detection signals A3 and B3. be able to.

The control circuit 8 is the brushless motor 1
When switching from synchronous operation to operation by position detection,
Input position detection signal A during operation by the same position detection
3, a control signal for switching the energization of each armature winding is output according to the timing of B3 and the obtained position detection signal C3. Therefore, as in the previous embodiment, the software processing in the control circuit 8 is sufficient, so that the same operation and effect as in the previous embodiment can be obtained.

Further, in the above-described two embodiments, the timing of the remaining position detection signals is obtained by using the two position detection signals obtained based on the terminal voltages U, V, W of the armature windings of the brushless motor 1. Is obtained, but based on the terminal voltage 1
One position detection signal may be obtained, and the timings of the other two position detection signals may be estimated based on this one position detection signal.

In this case, refer to FIG. 1 for the controller of this brushless motor. Further, the position detection unit 7 of this control device outputs one position detection signal based on the input terminal voltage U, for example.

Then, the control circuit 8 detects the rising edge and the falling edge of one position detection signal obtained by the position detecting section 7, and divides the time between these edges into a plurality of equal parts, and obtains them. The timing of the equally divided time from the rising or falling of one position detecting signal is defined as the rising or falling of the remaining two position detecting signals.

As a result, a control signal for switching the energization of the armature winding of the brushless motor is output based on the timing of the obtained one position detection signal and the timing of the estimated two position detection signals. be able to.

As still another method, the control circuit 8 detects the rising timing and the falling timing of one position detection signal obtained by the position detecting section 7, and equally divides the time between these timings into a predetermined number. After that, when the rising or falling timing of one obtained position detecting signal (position detecting signal after a half cycle or one cycle) is detected, the equal division is made from the detected rising or falling timing. The timing of time is defined as the rising and falling edges of the remaining two position detection signals.

As a result, similarly to the above, the control for switching the energization of the armature winding of the brushless motor based on the timing of the obtained one position detection signal and the timing of the estimated two position detection signals. A signal can be output.

As described above, since only one position detection signal is obtained based on the terminal voltages U, V, W of each armature winding of the brushless motor 1, the number of circuit components of the position detection unit 7 can be reduced. Not only is the number of lines of the position detection signal reduced.

[0051]

As described above, according to the rotor position detecting method for a brushless motor of the present invention, the energization of a plurality of armature windings of a sensorless DC brushless motor (brushless motor) is performed by the rotor of the brushless motor. When switching based on position detection, a predetermined number of position detection signals are obtained based on the multiple armature windings of the brushless motor, the rising and falling edges of this position detection signal are detected, and the time between these edges is detected. In addition to measuring, the other position detection signal is estimated from this measurement time and the edge timing of the position detection signal, so the number of parts of the circuit that detects the position of the rotor of the brushless motor is reduced, that is, The position detection circuit can be simplified and the number of position detection signal lines can be reduced. It is possible to reduce the number, there is a useful effect that it is possible to turn cost reduction.

[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 flowchart illustrating the operation of the controller for the brushless motor shown in FIG.

FIG. 4 is a schematic flow chart illustrating another embodiment of the present invention.

FIG. 5 is a schematic flowchart illustrating another embodiment of the present invention.

FIG. 6 is a schematic block diagram of a conventional brushless motor control device.

FIG. 7 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) 1a Rotor (of Brushless Motor 1) 2 Inverter Section 3,7 Position Detection Section 4,8 Control Circuit (Microcomputer) 5 Chopping Section 6 Driver Section a Spike Voltage U, V, W Terminal voltage of armature winding

Claims (5)

[Claims] 1. When switching energization of a plurality of armature windings of a brushless motor based on a position detection signal of a rotor of the brushless motor, at least based on terminal voltages of the plurality of armature windings of the brushless motor. While obtaining one position detection signal, the timing of the remaining position detection signal is estimated based on the time between the edges of the obtained position detection signal and the timing of the same position detection signal. Method for detecting rotor position of brushless motor. 2. When the energization of the armature winding of the three-phase brushless motor is switched based on the position detection signal of the rotor of the brushless motor, the rotation is performed based on the terminal voltage of the armature winding of the brushless motor. 2 for child position detection signal
Meanwhile, the time Ta1 from the rising edge of one position detection signal of the obtained two position detection signals to the falling edge of the other position detection signal is measured,
Further, the time Ta2 from the falling edge of the same position detection signal to the rising edge of the other position detection signal.
Is measured, and the time when the measured time Ta1 has elapsed from the falling edge of the other position detection signal is defined as the rising edge of the remaining position detection signal, and the measured time Ta2 is measured from the rising edge of the other position detection signal. Is the trailing edge of the remaining position detection signal, and the energization of the armature winding of the brushless motor is performed based on the timings of the obtained two position detection signals and the timing of the remaining position detection signal. A method for detecting a rotor position of a brushless motor, characterized in that the rotor position can be switched. 3. When the energization of the armature winding of the three-phase brushless motor is switched based on the position detection signal of the rotor of the brushless motor, the rotation is performed based on the terminal voltage of the armature winding of the brushless motor. 2 for child position detection signal
Meanwhile, the time tb1 from the rising edge of one of the obtained position detection signals to the rising edge of the other position detection signal is measured.
Further, the time tb2 from the falling edge of the same position detection signal to the falling edge of the other position detection signal.
Is measured, and the time when the measured time tb1 has elapsed from the rising edge of the one position detection signal is defined as the trailing edge of the remaining position detection signal, and the measured time from the trailing edge of the one position detection signal. The time when tb2 has elapsed is defined as the rising edge of the remaining position detection signal,
The rotor position of the brushless motor, wherein energization of the armature winding of the brushless motor can be switched based on the timings of the two obtained position detection signals and the timings of the remaining position detection signals. Detection method. 4. When the energization of the armature winding of the three-phase brushless motor is switched based on the position detection signal of the rotor of the brushless motor, the rotation is performed based on the terminal voltage of the armature winding of the brushless motor. Child position detection signal is 1
On the other hand, the rising timing and the falling timing of the obtained position detection signal are detected, and the time between the timings is equally divided into a predetermined number to obtain the rising or falling of the obtained position detection signal. The other two position detection signals are estimated from the timing based on the timing of each of the equally divided times, and the timing of the obtained one position detection signal and the timing of the estimated two position detection signals are estimated. A method for detecting a rotor position of a brushless motor, wherein energization of an armature winding of the brushless motor can be switched based on the above. 5. When the energization of an armature winding of a three-phase brushless motor is switched based on a position detection signal of a rotor of the brushless motor, the rotation is performed based on a terminal voltage of the armature winding of the brushless motor. Child position detection signal is 1
Meanwhile, the rising timing and the falling timing of the obtained one position detection signal are detected, and the time between the timings is equally divided into a predetermined number, and the rising edge of the one position detection signal obtained thereafter is obtained. Alternatively, when the fall timing is detected, the other two position detection signals are estimated from the detected rise or fall timing by the timing of each of the equally divided times, and the obtained one position is detected. A method for detecting a rotor position of a brushless motor, wherein energization of an armature winding of the brushless motor can be switched based on a timing of a detection signal and a timing of the estimated two position detection signals.