JPH0739185A - Rotor position detecting method for brushless motor and detecting circuit therefor - Google Patents

Abstract

PURPOSE:To enhance an efficiency of rotation of a brushless motor and to conduct power conservation by maintaining a phase delay of an output signal (position detection signal) to a signal (input signal) by an armature voltage in a rotor position detector for the motor. CONSTITUTION:A rotor position detector for a brushless motor 1 which detects a position of a rotor of the motor 1 based on a terminal voltage of an armature winding of the motor 1, inputs terminal voltages U, V, W of armature windings of the motor 1 to first to third phase delay point detectors 20, 21, 22 to detect frequencies of voltages to be applied to the windings with spike pulses included in the voltages U, V, W and to detect predetermined phase (60 degrees) delay points from the pulses. These detected points and the frequencies of the pulses are input to a calculator 23, which calculates position detection signals Ua, Va, Wa delayed at 90 degrees (ideal value) in phase from the voltages U, V, W of the respective armature windings with a neutral point as a reference.

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, etc., and more specifically, it suppresses a phase shift of a position detection signal irrespective of the rotation frequency to rotate the rotor. The present invention relates to a rotor position detecting method for a brushless motor and a detecting circuit therefor for improving efficiency and saving power.

[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 4-pole brushless motor, the rotor position detection circuit of the brushless motor 1 shown in FIG. 5 is required.

In FIG. 1, this rotor position detecting circuit is composed of a terminal voltage (12) of the armature winding of the brushless motor 1.
LPFs (low-pass filters) 2 to 4 for integrating armature voltages U, V, and W having different 0 ° phases, and a voltage dividing resistor circuit for combining two signals of these integrated signals at a predetermined resistance ratio. 5 to 7, each terminal voltage U,
V and W are compared with the signals synthesized by the voltage dividing resistance circuits 5 to 7, respectively, and the signal (position detection signal) U of this comparison result is compared.
Comparator units 8, 9, 10 for outputting a, Va, Wa
It has and.

Specifically, each LPF 2 to 4 will be described.
While inputting the signals integrated by the above into the positive input terminals of the operational amplifiers of the comparator sections 8 to 10, the signals input to the negative input terminals of each operational amplifier are combined and combined with signals other than the input signal to the positive input terminals. Enter. The voltage dividing resistor circuits 5 to 7 for synthesizing these two signals respectively have resistors R1 to R6 of a predetermined value.
The resistance ratio of the voltage dividing resistor circuits 5 to 7 is set so as to correct the phase delay of the output signal with reference to the neutral point a (shown in FIG. 6) of the terminal voltage of the armature winding. .

As a result, as shown in FIG. 6, the armature voltage (terminal voltage of the armature winding) U of the brushless motor 1,
Assuming that V and W (shown in (a) to (c) of the same figure) are input to the position detection circuit having the above-mentioned configuration, the same figure (d) is shown.
As shown in (f) to (f), the output signals Ua, Va, Wa from the position detection circuit are the terminal voltages U,
For V and W, the phase 90 with respect to the neutral point a
It will change after a delay (ideal value).

Further, the signals Ua, V having the 90-degree phase delay are also provided.
a and Wa are input to a control circuit (not shown), and the control circuit controls the brushless motor 1 by a 120-degree energization type drive system so that the input signals Ua, Va and Wa are input to the rotor of the brushless motor 1. Is used as a position detection signal for driving the transistor of the drive circuit 11 on and off in a predetermined manner.

[0007]

However, in the rotor position detecting circuit of the brushless motor, the terminal voltages U, V, V of the armature winding are changed by the rotation frequency of the brushless motor 1 (by changing the rotation frequency). Since the phase delay of the output signals Ua, Va, Wa with respect to W changes more than the ideal 90 degrees with reference to the neutral point, and the phase delay changes in the range of 70 degrees to 110 degrees, the rotation efficiency of the brushless motor is increased. There is a problem that the power consumption is lowered and eventually the power consumption is increased.

The present invention has been made in view of the above problems, and an object thereof is to maintain a constant phase delay of an output signal with respect to an input signal when detecting the position of a rotor of a brushless motor, and to maintain the rotation of the brushless motor. It is an object of the present invention to provide a method for detecting a rotor position of a brushless motor and a circuit for the same, which can achieve high efficiency and eventually power saving.

[0009]

In order to achieve the above object, the present invention is directed to a rotor position of a brushless motor for detecting the position of the rotor of the brushless motor based on a terminal voltage of an armature winding of the brushless motor. A detection method,
When a specific phase of the armature winding of the brushless motor is sequentially excited to control the rotation of the brushless motor, a spike pulse generated at the rise and fall of the voltage applied to the armature winding causes the same motor to rotate. Detects the frequency of the voltage applied to the child winding, detects the predetermined phase delay point from the spike pulse, and detects the frequency applied to the armature winding based on the detected frequency and the predetermined phase delay point. The gist is that a position detection signal with a predetermined phase delay is obtained.

[0010]

With the above means, the frequency of the terminal voltage of the armature winding of the brushless motor is detected with the spike pulse as a reference, and the signal of this detection frequency is divided into a predetermined (1/2) and a rectangular wave ( Voltage waveform). The amplitude of the signal thus obtained is varied according to its detection frequency,
For example, when the rotation frequency of the brushless motor (the frequency of the terminal voltage of the armature winding) is high, the amplitude of the signal is reduced, and when the frequency of the signal of the input voltage is low, the amplitude of the signal is increased.

The signal whose amplitude has been changed is converted into an integrator (LP
A sawtooth wave is passed through F), the signal is compared with a predetermined threshold voltage, and a predetermined phase delay point is obtained from the spike pulse by the comparison result. At this time, the predetermined threshold voltage is changed according to the frequency of the signal whose level is changed.

Therefore, in the case of a four-pole brushless motor, for example, the 60-degree phase point is detected with respect to the terminal voltages (voltages with 120-degree phase difference) U, V, and W of the armature winding of the brushless motor 1. When the rotation frequency of the brushless motor is changed, the amplitude of the divided signal and the predetermined threshold voltage are changed, and the predetermined phase delay point from the spike pulse is the terminal voltage U, V, W of the armature winding. The phase is set to 60 degrees.

The frequency and phase of the detected spike pulse are 60 degrees, and the phase is 9 with respect to the terminal voltage U, V, W of each armature winding with reference to the neutral point a.
A signal delayed by 0 degrees (ideal value) can be obtained. Therefore, even if the rotation frequency of the brushless motor 1 changes, the position detection signals Ua, Va, which are delayed by 90 degrees (ideal value) from the neutral point a with respect to the signals U, V, W by each armature voltage, W
The deviation of the phase shift of a is small, that is, the phase delay is kept near 90 degrees regardless of the rotation frequency of the brushless motor.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless motor rotor position detecting method and its circuit according to the present invention apply a sequential excitation to a specific phase of an armature winding of a sensorless DC brushless motor (hereinafter referred to as a brushless motor) to rotate the brushless motor. When controlling, the rise of the voltage applied to the armature winding,
And a spike pulse b (shown in FIGS. 3 and 6) generated at the falling edge is used. The frequency of the voltage applied to the armature winding is detected by the spike pulse b, and A predetermined phase delay point is detected, and based on the detected frequency and the predetermined phase delay point, the voltage applied to the armature winding has a predetermined phase based on the neutral point a of the armature winding terminal voltage. The position detection signal of the rotor of the brushless motor delayed only by this is obtained.

Therefore, the rotor position detecting circuit of the brushless motor of the present invention has the structure shown in FIGS. 1 and 2. In the figure, the same parts as those in FIG.

In FIG. 1, this rotor position detecting circuit causes the armature winding of the 4-pole brushless motor 1 to generate a spike pulse b generated at the rise and fall of the voltage applied to the armature winding. The first to third phase delay point detection units 20, 21, 22 which detect the frequency of the applied voltage and also detect the predetermined phase delay point from the spike pulse b, and the detected frequency and predetermined phase delay point Input and the terminal voltage U, V, W of each armature winding
On the other hand, an arithmetic unit 23 for calculating position detection signals Ua, Va, Wa delayed by a predetermined phase (for example, 90 degrees) with respect to the neutral point a is provided.

The first phase delay point detection section 20 applies the input signal (spike pulse b included in the terminal voltage U of the armature winding; shown in FIGS. 3 and 6) to the armature winding. The basic frequency detecting section 20a for detecting the frequency (fundamental frequency) of the voltage, the frequency dividing section 20b for dividing the detected basic frequency by a predetermined (for example, 1/2), and the frequency of the divided signal. An f / V (frequency / voltage) converter 20c for converting the voltage, a level converter 20d for varying the level of the converted voltage signal according to the frequency, and an integration of the level-converted signal and the same level. A predetermined threshold voltage is obtained from the converted signal, the integrated signal is compared with a predetermined threshold voltage, and a phase 60-degree point detection unit 20e for detecting a point delayed by 60 degrees with respect to the divided signal.
It has and.

The phase 60-degree point detecting section 20e has an L level for integrating the input signal (level-converted voltage signal).
A PF (low-pass filter) 20f, a threshold voltage control section 20g for obtaining a predetermined threshold voltage from the same input signal, and varying the predetermined threshold voltage according to the frequency of a signal obtained by dividing the predetermined threshold voltage, and A comparator section 20h is provided to obtain a point delayed by a predetermined phase (60 degrees) from the signal obtained by comparing the integrated signal with the threshold voltage and dividing the frequency.

The second and third phase delay point detectors 21 and 22 have the same structure as the first phase delay point detector 20, and the fundamental frequency detectors 21a and 22a are the fundamental frequency detector 20a. The frequency dividers 21b and 22b are the frequency dividers 20b.
And f / V (frequency / voltage) converters 21c and 22c are f
/ V (frequency / voltage) converter 20c and level converter 2
1d and 22d are the same as the level converting unit 20d, and 60 ° phase detecting units 21e and 22e are the same as the 60 ° phase detecting unit 20e. Further, the 60-degree phase detectors 21e and 22e have the same configuration as shown in FIG.

Next, the operation of the position detecting circuit of the brushless motor will be described in detail with reference to the time chart of FIG. 3 and the explanatory view of FIG. 4. First, rotation control of the 4-pole brushless motor 1 is performed.

In this case, the drive circuit 11 outputs the voltage applied to the armature winding of the brushless motor 1 as in the conventional case,
Excitation is sequentially applied to a specific phase of the armature winding of the brushless motor 1. Then, the terminal voltages U, V, W of the armature winding of the brushless motor 1 have the voltage waveforms shown in FIG.

The terminal voltage U of the armature winding is input to the fundamental frequency detecting section 20a, and the fundamental frequency detecting section 20a is the spike pulse b included in the terminal voltage U of the armature winding.
To detect the frequency (the basic frequency of the voltage applied to the armature winding) (shown in FIG. 3B). The detection of the fundamental frequency is performed based on the spike pulse b generated at the rising of the voltage applied to the armature winding.

The frequency division section 20b inputs the signal of that frequency and divides it into 1/2, and the f / V conversion section 20c converts the signal of the frequency divided into 1/2 into a voltage signal. The level conversion unit 20d that receives the signal of this voltage changes the amplitude of the signal according to the frequency.

For example, when the frequency of the signal of the input voltage is high, the amplitude of the signal is reduced, and when the frequency of the signal of the input voltage is low, the amplitude of the signal is increased. Then, this level-converted signal is used as the phase 60-degree point detection unit 20.
It is input to e, and a point delayed by 60 degrees with respect to the rise of the voltage applied to the armature winding (spike pulse b) is detected.

More specifically with reference to FIG. 4, the threshold voltage control unit 20g varies the threshold voltage of the output according to the frequency of the input signal c. For example, when the amplitude of the input signal c is reduced by the level converter 20d, the slope of the signal d integrated by the LPF 20f becomes gentle. Therefore, the threshold voltage control unit 20g decreases the output threshold voltage as the frequency of the input signal increases. Conversely, when the level converter 20d increases the amplitude of the input signal c, the slope of the signal d integrated by the LPF 20f becomes steep. Therefore, the threshold voltage control unit 20g increases the output threshold voltage as the frequency of the input signal increases.

From the above, even if the frequency of the spike pulse b (that is, the frequency of the voltage applied to the armature winding) is changed, the output threshold voltage of the threshold voltage control unit 20g is changed. The output of the comparator section 20h of the phase 60-degree point detection section 20e always outputs a signal delayed by 60 degrees of a predetermined phase from the spike pulse b.

This predetermined phase of 60 degrees is located where the phase is delayed by 90 degrees (ideal value) with respect to the neutral point a with respect to the signal U due to the armature voltage, and the comparator section 2
The output signal of 0h corresponds to the timing of the rotor position detection signal Ua of the brushless motor 1.

In this way, the first phase delay point detection unit 20 has a 60 degree delay point of a predetermined phase from the spike pulse b and the frequency of the spike pulse b (fundamental frequency;
The frequency of the voltage applied to the armature winding is output.

Further, the second and third phase delay point detecting sections 2 are generated by the terminal voltages V and W of the armature winding, that is, by the spike pulse b included in the terminal voltages V and W.
1 and 22 perform the same operation as described above, and the spike pulse b
From the predetermined phase to the 60-degree delay point and the spike pulse b
The frequencies of are output respectively.

The first to third phase delay point detection units 20,
The signals from 21, 22 that is, the 60-degree delay point of the predetermined phase from the spike pulse b and the frequency of the spike pulse b are input to the calculation unit 23, and the calculation unit 23 is based on the information of the 60-degree delay point of the predetermined phase. , A signal is output at the timing of the frequency of the spike pulse b. Therefore, the output signal from the arithmetic unit 23 is the terminal voltage U, V,
90 degree phase with respect to W based on neutral point a (ideal value)
The signals are delayed, that is, the position detection signals Ua, Va, Wa of the rotor of the brushless motor 1 (shown in FIG. 3D and FIGS. 6D to 6F).

As described above, if the rotation frequency of the brushless motor 1 changes, the level converters 20d, 21d, 22.
Since the level conversion in d changes and the threshold voltage in the threshold voltage control unit 20f of the phase 60-degree point detection unit 20e changes, the comparator units 20h, 21h,
22h, the result of the comparison, signal U by each armature voltage,
Signals having a phase delay of 60 degrees with respect to the spike pulse b included in V and W are obtained.

Therefore, even if the rotation frequency of the brushless motor 1 changes, the comparator units 20h, 21h, 2
The phase delay of the output signal of 2h, that is, the output signals Ua, Va, Wa (position detection signals) becomes stable near 90 degrees (for example, within ± 10 degrees). That is, the position detection signals Ua, Va, which are delayed by 90 degrees (ideal value) in phase with respect to the neutral point a with respect to the signals U, V, W by each armature voltage,
The deviation of the phase shift of Wa is reduced, and the rotation efficiency of the brushless motor 1 is increased, and the power consumption can be reduced.

[0033]

As described above, according to the rotor position detecting method for a brushless motor and its circuit of the present invention, a specific phase of the armature winding of the brushless motor is sequentially excited to rotate the brushless motor. At the time of control, a spike pulse b (shown in FIGS. 3 and 6) generated at the rise and fall of the voltage applied to the armature winding is used, and the spike pulse b is applied to the armature winding. The frequency of the voltage to be applied is detected, a predetermined phase delay point is detected from the spike pulse b, and the armature winding is applied to the voltage applied to the armature winding based on the detected frequency and the predetermined phase delay point. Since the position detection signal of the rotor of the brushless motor delayed by a predetermined phase with respect to the neutral point a of the terminal voltage of the line is obtained, the rotation of the brushless motor 1 is reduced. Regardless of variations in the frequency can be a constant phase (90 ° near) delayed the neutral point as a reference to the input signal (the terminal voltage of the armature winding),
The phase delay is always near a constant value (90 degrees ± 10), that is, the deviation of the phase shift is small, the rotation efficiency of the brushless motor can be improved, and the power consumption can be saved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a rotor position detection circuit of a brushless motor showing an embodiment of the present invention.

FIG. 2 is a schematic partial circuit diagram of a rotor position detection circuit of the brushless motor shown in FIG.

3 is a schematic time chart diagram for explaining the operation of a rotor position detection circuit of the brushless motor shown in FIG.

FIG. 4 is an explanatory diagram illustrating an operation of a rotor position detection circuit of the brushless motor shown in FIG.

FIG. 5 is a schematic block diagram of a rotor position detection circuit of a conventional brushless motor.

6 is a schematic time chart diagram for explaining the operation of the rotor position detection circuit of the brushless motor shown in FIG.

[Explanation of symbols]

1 Brushless Motor (Sensorless DC Brushless Motor) 11 Drive Circuit 20 First Phase Delay Point Detector 20a, 21a, 22a Basic Frequency Detector 20b, 21b, 22b Frequency Divider 20c, 21c, 22c f / V (Frequency / Voltage) ) Conversion unit 20d, 21d, 22d Level conversion unit 20e, 21e, 22e Phase 60 degree point detection unit 20f LPF (low pass filter) 20g Threshold voltage control unit 20h Comparator unit 21 Second phase delay point detection unit 22 Third Phase lag point detection unit 23 Calculation unit a Neutral point b Spike pulse U, V, W Armature winding terminal voltage (signal by armature voltage) Ua, Va, Wa output signal (position detection signal)

Claims (4)

[Claims] 1. A rotor position detecting method for a brushless motor for detecting the position of a rotor of the brushless motor based on a terminal voltage of the armature winding of the brushless motor, comprising: When the brushless motor is rotationally controlled by sequentially exciting specific phases, the frequency of the voltage applied to the armature winding is increased by the spike pulse generated at the rise and fall of the voltage applied to the armature winding. And a predetermined phase delay point is detected from the spike pulse, and a position detection signal having a predetermined phase delay with respect to the voltage applied to the armature winding is obtained based on the detected frequency and the predetermined phase delay point. A method for detecting the rotor position of a brushless motor, characterized in that 2. A brushless motor rotor position detecting method for detecting the position of the rotor of the brushless motor based on the terminal voltage of the armature winding of the brushless motor, wherein the armature winding of the brushless motor comprises: The frequency of the terminal voltage is detected based on the spike pulse generated at the rise and fall of the applied voltage, a signal obtained by dividing the frequency of the detected signal by a predetermined frequency is obtained, and the frequency of the obtained signal is converted into a voltage. And the amplitude of the converted voltage signal is varied according to the magnitude of the frequency to obtain a predetermined threshold voltage corresponding to the varied amplitude signal, and the variable amplitude signal is integrated. A signal is compared with the predetermined threshold voltage to detect a predetermined phase delay point from the spike pulse, and the detected predetermined phase delay point and the frequency of the spike pulse are used as the basis. There obtaining the position detection signal of the rotor of the brushless motor, a rotor position detecting method for a brushless motor, characterized in that the position detection signal was 該得 was predetermined phase lag with respect to the terminal voltage. 3. A rotor position detection circuit for a brushless motor, which detects the position of the rotor of the brushless motor based on the terminal voltage of the armature winding of the brushless motor, the armature winding of the brushless motor comprising: The frequency of the terminal voltage is detected based on the spike pulse generated at the rise and fall of the applied voltage, a signal obtained by dividing the frequency of the detected signal by a predetermined frequency is obtained, and the frequency of the obtained signal is converted into a voltage. And the amplitude of the converted voltage signal is varied according to the magnitude of the frequency to obtain a predetermined threshold voltage corresponding to the varied amplitude signal, and the variable amplitude signal is integrated. Phase delay point detection means for detecting a predetermined phase point from the spike pulse by comparing the signal with the predetermined threshold voltage, and spy detected by the first phase delay point detection means The position detection signal of the rotor of the brushless motor is obtained from the pulse on the basis of the predetermined phase delay point and the frequency of the spike pulse, and the position detection signal is delayed by a predetermined phase with respect to the terminal voltage. A rotor position detection circuit for a brushless motor characterized by the above. 4. A rotor position detection circuit for a brushless motor that detects the position of the rotor of the brushless motor based on the terminal voltage of the armature winding of the 4-pole brushless motor, the armature of the brushless motor. The frequency of the terminal voltage is detected based on the spike pulse generated at the rise and fall of the voltage applied to the winding, and the signal of the detected frequency is divided into predetermined signals to obtain the obtained signals. The frequency of the signal is converted into a voltage, the amplitude of the signal of the converted voltage is varied according to the magnitude of the frequency, and a predetermined threshold voltage corresponding to the signal of the varied amplitude is obtained and the same variable. The first to third positions for detecting the phase 60 degree point from the spike pulse by comparing the signal obtained by integrating the signal having the given amplitude with the predetermined threshold voltage. From the delay point detection means and the spike pulse detected by the phase delay point detection means, a position detection signal of the rotor of the brushless motor is obtained based on the phase 60 degree delay point and the frequency of the spike pulse, and the same position detection signal is obtained. And a calculation means for delaying the phase of the terminal voltage by 90 degrees with respect to the neutral point of the terminal voltage.