JPH07274581A - Drive circuit for brushless motor - Google Patents

Abstract

PURPOSE:To detect deviations from the correct sequence of phases for higher stability and reliability of motor drive. CONSTITUTION:The title drive circuit for brushless motors consists of a position detection circuit 3 that detects the relative positional relation between stator coils 1 and a rotor magnet 2; a phase switching timing generating circuit 4 that is fed with the position signals detected through the position detection circuit 3, and that generates a phase switching signal when the phase of the position detecting signals switches; and a phase sequence detecting circuit 5 that judges whether the motor is driven in the specified phase sequence, according to the position signals and the phase switching signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for driving a brushless motor, and more particularly to detection of a phase switching sequence abnormality.

[0002]

2. Description of the Related Art A conventional brushless motor drive circuit is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-111285. This is to output an error signal when the information of the rotation direction of the motor and the change of the sensor signal for detecting the phase state of the motor in a three-phase brushless motor are out of a predetermined order.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the conventional detection method disclosed in Japanese Patent No. 1285,
As shown in FIG. 13, sensor output signals CSU, CS
All the noises generated in V and CSW are detected and an error signal is output. However, in the brushless motor, if small noise or chattering at the time of phase switching of the position signal is recognized as an error, there is a problem that the stability of the motor drive deteriorates.

The present invention has been made to solve the above problems, and provides a brushless motor drive device capable of detecting abnormality in the original sequence of phases and achieving stability and reliability of motor drive. The purpose is to get.

[0005]

A drive circuit for a brushless motor according to a first aspect of the present invention is a drive circuit for a brushless motor having a stator coil and a rotor magnet rotated by a rotating magnetic field generated by the stator coil. Position detection means for detecting the relative position of the coil and the rotor magnet, and phase switching timing generation means for inputting the position signal detected by the position detection means and for generating a phase switching signal when the phase of the position signal switches. , A phase sequence detection means for determining whether or not the motor is driven in a predetermined phase sequence based on the position signal and the phase switching signal.

A brushless motor drive circuit according to a second aspect of the present invention is a brushless motor drive circuit having a stator coil and a rotor magnet rotated by a rotating magnetic field generated by the stator coil. Position detection means for detecting the relative position by detecting the magnetic field of the rotor magnet, and the position signal detected by the position detection means are input, and when the phase of the position signal switches, a pulse signal of a predetermined width is generated. Based on the phase switching timing generating means, the position signal and the pulse signal, it is determined whether or not the motor is driven in a predetermined phase sequence, and an error signal is output when the motor is not rotating in the predetermined phase sequence. And a phase sequence detecting means.

A brushless motor drive circuit according to a third aspect of the present invention is a brushless motor drive circuit having a stator coil and a rotor magnet rotated by a rotating magnetic field generated by the stator coil. Position detecting means for detecting the relative position by the counter electromotive voltage generated in the stator coil,
When the position signal detected by the position detecting means is input and the phase of the position signal is switched, a phase switching timing generating means for generating a pulse signal of a predetermined width, and a motor based on the position signal and the pulse signal And a phase sequence detecting means for outputting an error signal when the motor is not rotating in a predetermined phase sequence.

In the brushless motor drive circuit according to the fourth aspect of the present invention, the phase sequence detecting means according to the second aspect or the third aspect includes the first and second D flip-flops to which the position signal is input, The pulse signal includes a third D flip-flop to which the output of the first D flip-flop is input, and an exclusive OR circuit to which the outputs of the first D flip-flop and the third D flip-flop are input. Is input as a clock of the first, second and third D flip-flops, and the output of the exclusive OR circuit is output as an error signal. In the brushless motor drive circuit according to the fifth aspect of the present invention, the phase sequence detection means is a drive signal for driving a stator coil, in place of the phase sequence detection means according to claim 1, 2 or 3. Based on the phase switching signal or the pulse signal, it is determined whether the motor is rotating in a predetermined phase order.

In the brushless motor drive circuit according to the sixth aspect of the present invention, the phase sequence detection means according to claim 5 outputs the ring counter to which the phase switching signal or the pulse signal is input, and the drive signal and the output signal of the ring counter. And a comparator for comparing and outputting an error signal.

[0010]

In the first aspect of the invention, the position detecting means allows
The relative position between the stator coil and the rotor magnet is detected, and the phase switching timing generating means inputs the position signal detected by the position detecting means, and when the phase of the position signal switches, a phase switching signal is generated and The forward detection means determines whether or not the motor is driven in a predetermined phase sequence based on the position signal and the phase switching signal. In the second invention, the relative position between the stator coil and the rotor magnet is detected by the position detecting means by detecting the magnetic field of the rotor magnet, and the position signal detected by the position detecting means by the phase switching timing generating means. Is inputted and a pulse signal of a predetermined width is generated when the phase of the position signal is switched, and whether or not the motor is driven in a predetermined phase sequence based on the position signal and the pulse signal by the phase sequence detection means. If the motor is not rotating in a predetermined phase sequence, an error signal is output.

In the third invention, the position detecting means detects the relative position of the stator coil and the rotor magnet by the counter electromotive voltage generated in the stator coil, and the phase switching timing generating means detects the position detecting means. When the position signal is input and the phase of the position signal switches, a pulse signal with a predetermined width is generated,
Based on the position signal and the pulse signal, the phase sequence detection means determines whether or not the motor is driven in a predetermined phase sequence, and when the motor is not rotating in the predetermined phase sequence, an error signal is output. It In the fourth invention, the phase sequence detecting means includes first and second D flip-flops to which a position signal is input, a third D flip-flop to which an output of the first D flip-flop is input, An exclusive OR circuit to which the outputs of the first D flip-flop and the third D flip-flop are input, and the pulse signal is input as a clock of the first, second and third D flip-flops. And the output of the exclusive OR circuit is output as an error signal.

In the fifth aspect of the invention, the phase sequence detecting means determines whether the motor is rotating in a predetermined phase sequence based on the drive signal for driving the stator coil and the phase switching signal or the pulse signal. It In the sixth invention, the phase sequence detecting means includes a ring counter to which the phase switching signal or the pulse signal is input, and a comparator which compares the drive signal with the output signal of the ring counter and outputs an error signal. .

[0013]

【Example】

Example 1. 1 is a block diagram showing the configuration of a drive circuit of a brushless motor according to an embodiment of the present invention, this example is a three-phase brushless motor. In the figure, 1 is a stator coil, 1a is a U-phase stator coil, 1b is a V-phase stator coil, 1c is a W-phase stator coil, 2 is a rotor magnet, 3 is a position for detecting the relative position of the stator coil 1 and the rotor magnet 2. A detection circuit 4 is a phase switching timing generation circuit that generates a signal when a signal of the relative position detected by the position detection circuit 3 is input and the phase is switched, and 5 is a phase sequence that determines whether the phases are switched in a predetermined order. A detection circuit, 6 is a logic processing circuit that outputs a drive signal for the stator coil 1, and 7 is an output stage that supplies electric power to the stator coil 1 based on the drive signal from the logic processing circuit 6.

Next, the operation of this embodiment will be described.
FIG. 2 is a diagram showing output signals of the position detection circuit 3 and the phase switching timing generation circuit 4 when the brushless motor is rotating in the CW direction. FIG. 3 shows outputs of the position detection circuit 3 and the phase switching timing generation circuit. It is explanatory drawing for demonstrating a relationship.

First, the position detection circuit 3 includes the stator coil 1
And the relative position of the rotor magnet 2 are detected, and the position detection signals shown in FIGS. 2A, 2B and 2C are output. Then, this position detection signal is input to the phase switching timing generation circuit 4 and the phase switching timing generation circuit 4
Based on the input position detection signal, as shown in (d) of FIG. 2, generates and outputs a phase switching signal having an ON time of a predetermined time each time the phase of each position detection signal switches. .

The position detection signal and the phase switching signal are input to the phase sequence detection circuit 5, and the phase sequence detection circuit 5 observes the state of the position detection signal at that time in synchronization with the fall of the phase switching signal. Therefore, it is determined whether the motor is rotating in a predetermined phase order. When it is determined that the sequence is out of the correct order, an error signal is output.

In this embodiment, the phase sequence detection circuit 5 determines the phase sequence by the falling edge of the clock of the phase switching signal having an ON time of a predetermined time.
3A, even if chattering occurs when the position detection signal changes as shown in FIG. 3A, the phase switching signal is shown in FIG. 3B. As described above, there is an ON time of a predetermined time, it is possible to avoid chattering of the position detection signal occurring within the ON time, only phase sequence detection can be performed, and it is possible to accurately determine the phase sequence. Become. Although the example of the three-phase brushless motor is shown in this embodiment, a two-phase brushless motor or a multi-phase connected brushless motor may be used.

Example 2. FIG. 4 is a block diagram showing the configuration of a drive circuit for a brushless motor according to another embodiment of the present invention. This example is a drive circuit for a two-phase sensorless brushless motor. In the figure, 8 is an S phase coil and 9 is an M coil.
A phase coil, 10 is a midpoint potential (DC 140 V), 3 is a position detection circuit that compares the counter electromotive voltage generated in the S phase coil 8 and the M phase coil 9 with the midpoint potential 10, and outputs a position detection signal,
4 is a phase switching timing generation circuit that receives the position detection signal output from the position detection circuit 3 and that generates a signal when the phases are switched. 5 is a phase sequence detection circuit that determines whether the phases are switched in a predetermined order. 6 is an S-phase coil 8
And a logic processing circuit for outputting a drive signal for the M-phase coil 9,
An output stage 7 supplies electric power to the S-phase coil 8 and the M-phase coil 9 based on the drive signal from the logic processing circuit 6.

Next, the operation of this embodiment will be described.
FIG. 5 is a diagram showing the counter electromotive voltage generated in the S-phase coil 8 and the M-phase coil 9 and the output signal of each circuit. First, when the motor is rotating in a predetermined direction, the counter electromotive voltages as shown in FIGS. 5A and 5B are generated in the S-phase coil 8 and the M-phase coil 9, respectively. Then, the position detection circuit 3 compares the counter electromotive voltage with the midpoint voltage 10 to output a position detection signal as shown in (c) and (d) of FIG. Then, the logical processing circuit 6 outputs the drive signals S +, M +, S-, and M- shown in (f), (g), (h), and (i) of FIG. 5 based on the position detection signal, The motor is driven based on this drive signal.

Further, this position detection signal is input to the phase switching timing generation circuit 4, and the phase switching timing generation circuit 4 is based on the input position detection signal as shown in (e) of FIG. Each time the phase of each position detection signal is switched, a phase switching signal having an ON time of a predetermined time is generated and output. The position detection signal and the phase switching signal are input to the phase sequence detection circuit 5,
The phase sequence detection circuit 5 determines whether the motor is rotating in the correct phase sequence and outputs an error signal if it is determined that the motor is out of the correct sequence.

Next, the operation of the phase sequence detection circuit 5 for determining the phase sequence will be described. FIG. 6 shows the phase sequence detection circuit 5 of the second embodiment.
FIG. 7 is a circuit diagram showing an example, and FIG. 7 is a waveform diagram for explaining the phase sequence detection circuit 5. In FIG. 6, 20, 21, 2
2 is a D-type flip-flop, 23 is an EX-OR circuit, 2
4 is a NOT circuit, which is a D-type flip-flop 20, 2
Each of 1 and 22 operates by the fall of the phase switching signal.

In the phase sequence detection circuit 5, when the motor is rotating in a predetermined direction, the S phase position detection signal and the M phase position detection signal shown in FIGS. 7A and 7B are D type. It is inputted to the flip-flops 20 and 22, respectively. And
The output of the D-type flip-flop 20 is input to the D-type flip-flop 21, and the output of the D-type flip-flop 21 is the S phase synchronized with the falling edge of the phase switching signal as shown in (d) of FIG. The position detection signal is shifted by 90 degrees in phase.

The output of the D-type flip-flop 22 becomes an S-phase position detection signal in synchronization with the falling edge of the phase switching signal as shown in FIG. 7 (e). here,
When the motor is rotating in the correct phase sequence, the output of the D-type flip-flop 21 and the output of the D-type flip-flop 22 coincide with each other, so that the two outputs shown in (d) and (e) of FIG. In order to determine whether the signals match, the two signals are input to the EX-OR circuit 23. When the two signals do not match, the output of the EX-OR circuit 23 becomes H level, It is determined that the motor is not rotating in the correct phase sequence, which is an error signal.

In this embodiment, the phase sequence of the position detection signal is judged by the falling edge of the clock of the phase switching signal after the phase of the position detection signal is changed as in the first embodiment. It is possible to avoid chattering of the position detection signal that occurs within the pulse width time, perform only phase sequence detection, and accurately determine the phase sequence. Further, the phase sequence detection circuit 5 can be made to have a simple circuit configuration such as a flip-flop.

Example 3. FIG. 8 is a block diagram showing the configuration of a brushless motor drive circuit according to another embodiment of the present invention. This example is a two-phase sensorless brushless motor drive circuit. In the figure, 8 is an S phase coil and 9 is an M coil.
A phase coil, 10 is a midpoint potential (DC 140 V), 3 is a position detection circuit that compares the counter electromotive voltage generated in the S phase coil 8 and the M phase coil 9 with the midpoint potential 10, and outputs a position detection signal,
4 is a phase switching timing generation circuit that receives the position detection signal output from the position detection circuit 3 and that generates a signal when the phases are switched. 5 is a phase sequence detection circuit that determines whether the phases are switched in a predetermined order. 6 is an S-phase coil 8
And a logic processing circuit for outputting a drive signal for the M-phase coil 9,
An output stage 7 supplies electric power to the S-phase coil 8 and the M-phase coil 9 based on the drive signal from the logic processing circuit 6.

The operation of this embodiment will be described below.
FIG. 9 is a diagram showing the relationship between the position detection signal and the drive signal, FIG.
0 is a diagram showing an output signal of each circuit. First, when the motor is rotating in a predetermined direction, the S-phase and M-phase position detection signals output from the position detection circuit 3 shown in (a) and (b) of FIG. Is input, and depending on the state of the position detection signals of the S phase and M phase,
According to the truth table shown in FIG. 9, drive signals S +, M +, S-, and M- as shown in (c) to (f) of FIG. 10 are output, and the motor is driven based on this drive signal. It

The drive signals S +, M +, S-, M- and the phase switching signal are input to the phase sequence detection circuit 5, and the phase sequence detection circuit 5 judges whether the motor is rotating in the correct phase sequence. If it is determined that the sequence is out of the correct order, an error signal is output.

Next, the operation of the phase sequence detection circuit 5 for determining the phase sequence will be described. 11 is a circuit diagram showing an example of the phase sequence detection circuit 5 of the third embodiment, and FIG. 12 is a waveform diagram for explaining the phase sequence detection circuit 5. In FIG. 11, reference numeral 30 is a ring counter to which a phase switching signal is input, and here, a shift register is used. Reference numeral 31 is a comparator for comparing the output signal of the ring counter 30 and the drive signal.

The ring counter 30 sequentially outputs four waveforms shown in (a) to (d) of FIG. 12 in synchronization with the clock of the phase switching signal shown in (g) of FIG. This output is input to the comparator 31. Then, the drive signal S +, which is determined by the output position detection signal output from the logic processing circuit 6 shown in (c) to (f) of FIG.
M +, S-, and M- are input, and this drive signal and the output signal of the ring counter 30 are compared. If they match, it is determined that the phase order is correct. If they do not match, the phase order is not correct. Judges and outputs an error signal.

In this embodiment, the phase sequence can be determined by the drive signal output from the logic processing circuit 6, and the phase sequence can be detected without being directly affected by the noise of the position detection circuit 3, and the accurate phase sequence can be obtained. It becomes possible to judge.

[0031]

As described above, according to the first aspect of the invention, the position detecting means detects the relative position between the stator coil and the rotor magnet, and the phase switching timing generating means detects the relative position. When the position signal is input and the phase of the position signal is switched, a phase switching signal is generated, and whether the motor is driven in a predetermined phase sequence based on the position signal and the phase switching signal by the phase sequence detection means. Since the phase switching signal is used to determine the phase order, it is possible to avoid chattering that occurs when the phase of the position signal changes as an abnormal phase order, and to avoid brushless This has the effect that the motor can be driven stably and reliably.

According to the second invention, the relative position between the stator coil and the rotor magnet is detected by the position detecting means by detecting the magnetic field of the rotor magnet,
By the phase switching timing generation means, the position signal detected by the position detection means is input, and when the phase of the position signal is switched, a pulse signal of a predetermined width is generated,
The phase sequence detecting means determines whether or not the motor is driven in a predetermined phase sequence based on the position signal and the pulse signal, and outputs an error signal when the motor is not rotating in the predetermined phase sequence. Since the phase sequence is determined using a pulse signal of a predetermined width, it is possible to determine the phase sequence in synchronization with the falling edge of the pulse signal so that when the phase of the position signal changes. It is possible to reliably avoid the chattering that occurs and determine that the phase sequence is abnormal, and to drive the brushless motor in a stable and reliable manner.

According to the third invention, the position detecting means detects the relative position of the stator coil and the rotor magnet by the counter electromotive voltage generated in the stator coil, and the phase switching timing generating means detects the position detecting means. When the position signal is input and the phase of the position signal is switched, a pulse signal of a predetermined width is generated, and the phase sequence detection means drives the motor in a predetermined phase sequence based on the position signal and the pulse signal. It is determined whether or not, and when the motor is not rotating in a predetermined phase order, an error signal is output, so the phase order is determined using a pulse signal of a predetermined width. By determining the phase sequence in synchronization with the falling edge of the pulse signal, it is possible to reliably avoid chattering that occurs when the phase of the position signal changes as an abnormal phase sequence. , Stably drive the brushless motor, and has the effect that can be reliably performed.

According to the fourth aspect of the present invention, the phase sequence detecting means includes the first and second D flip-flops to which the position signal is input, and the third D-type input to which the output of the first D flip-flop is input.
And the exclusive OR circuit to which the outputs of the first D flip-flop and the third D flip-flop are input, and the pulse signals are the first, second and third D flip-flops. , And the output of the exclusive OR circuit is output as an error signal. Therefore, the phase sequence detecting means can be realized with a simple circuit configuration.

According to the fifth aspect of the invention, the phase sequence detecting means determines whether the motor is rotating in a predetermined phase sequence based on the drive signal for driving the stator coil and the phase switching signal or the pulse signal. Since the phase sequence is determined by using the drive signal for driving the stator coil, it is possible to directly determine the abnormality in the phase sequence without being affected by the noise in the position detection circuit. This has the effect that the brushless motor can be driven more stably and reliably. According to the sixth aspect, the phase sequence detecting means is composed of a ring counter to which the phase switching signal or the pulse signal is input, and a comparator which compares the drive signal and the output signal of the ring counter and outputs an error signal. As a result, there is an effect that the phase sequence detecting means can be realized with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a drive circuit of a brushless motor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing output signals of the position detection circuit 3 and the phase switching timing generation circuit 4 when the brushless motor of the first embodiment is rotating in the CW direction.

FIG. 3 is an explanatory diagram illustrating a relationship between outputs of a position detection circuit 3 and a phase switching timing generation circuit according to the first exemplary embodiment.

FIG. 4 is a block diagram showing a configuration of a drive circuit of a brushless motor according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a counter electromotive voltage generated in an S-phase coil 8 and an M-phase coil 9 of Example 2 and an output signal of each circuit.

FIG. 6 is a circuit diagram showing an example of a phase sequence detection circuit 5 according to a second embodiment.

FIG. 7 is a waveform diagram for explaining the phase sequence detection circuit 5 of the second embodiment.

FIG. 8 is a block diagram showing a configuration of a drive circuit of a brushless motor according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a relationship between a position detection signal and a drive signal according to the third embodiment.

FIG. 10 is a diagram showing an output signal of each circuit of the third embodiment.

FIG. 11 is a circuit diagram showing an example of a phase sequence detection circuit 5 according to a third embodiment.

FIG. 12 is a waveform diagram for explaining the phase sequence detection circuit 5 of the third embodiment.

FIG. 13 is an explanatory diagram illustrating a timing chart of a conventional three-phase commutation sensor.

[Explanation of symbols]

 1 Stator Coil 1a U Phase Stator Coil 1b V Phase Stator Coil 1c W Phase Stator Coil 2 Rotor Magnet 3 Position Detection Circuit 4 Phase Switching Timing Generation Circuit 5 Phase Sequence Detection Circuit 6 Logic Processing Circuit 7 Output Stage 8 S Phase Coil 9 M Phase Coil 10 Midpoint potential (DC140V) 20-22 D flip-flop 23 EX-OR circuit (exclusive OR circuit) 30 Ring counter 31 Comparator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kamo Shigeki 2-14-40 Ofuna, Kamakura-shi Inside Lifestyle Development Laboratory, Mitsubishi Electric Corporation (72) Yuichi Fukase 2-14-40 Ofuna, Kamakura Mitsubishi Electric Co., Ltd. Living Systems Development Laboratory (72) Inventor Takahiro Hayakawa 3-40 Shimoburo Tegano, Nakatsugawa City Mitsubishi Electric Engineering Co., Ltd. Nagoya Office Nakatsugawa Branch

Claims (6)

[Claims] 1. A position detection means for detecting a relative position between the stator coil and the rotor magnet in a drive circuit of a brushless motor having a stator coil and a rotor magnet rotated by a rotating magnetic field generated by the stator coil. Based on the position signal and the phase switching signal, and a phase switching timing generating means for inputting the position signal detected by the position detecting means and generating a phase switching signal when the phase of the position signal switches. A drive circuit for a brushless motor, comprising: a phase sequence detection unit that determines whether the motor is driven in a predetermined phase sequence. 2. In a drive circuit of a brushless motor having a stator coil and a rotor magnet rotated by a rotating magnetic field generated by the stator coil, the relative position of the stator coil and the rotor magnet is set to the magnetic field of the rotor magnet. Position detecting means for detecting by detecting, and a position signal detected by the position detecting means are inputted,
Phase switching timing generation means for generating a pulse signal of a predetermined width when the phase of the position signal is switched, and whether or not the motor is driven in a predetermined phase order based on the position signal and the pulse signal. And a phase sequence detecting means for outputting an error signal when the motor is not rotating in a predetermined phase sequence. 3. A brushless motor drive circuit having a stator coil and a rotor magnet rotated by a rotating magnetic field generated by the stator coil, wherein a relative position between the stator coil and the rotor magnet is generated in the stator coil. Position detecting means for detecting the back electromotive voltage, and the position signal detected by the position detecting means are inputted,
Phase switching timing generation means for generating a pulse signal of a predetermined width when the phase of the position signal is switched, and whether or not the motor is driven in a predetermined phase order based on the position signal and the pulse signal. And a phase sequence detecting means for outputting an error signal when the motor is not rotating in a predetermined phase sequence. 4. The phase sequence detection means includes first and second D flip-flops to which a position signal is input, and the first D flip-flop.
The pulse signal includes a third D flip-flop to which the output of the flip-flop is input, and an exclusive OR circuit to which the outputs of the first D flip-flop and the third D flip-flop are input. 4. The brushless according to claim 2 or 3, wherein is input as a clock of the first, second and third D flip-flops, and the output of the exclusive OR circuit is output as an error signal. Motor drive circuit. 5. The phase sequence detecting means, in place of the phase sequence detecting means according to claim 1, claim 2 or claim 3, the phase sequence detecting means includes a drive signal for driving the stator coil and the phase. A drive circuit for a brushless motor, wherein the drive circuit determines whether the motor is rotating in a predetermined phase sequence based on the switching signal or the pulse signal. 6. The phase sequence detection means comprises a ring counter to which the phase switching signal or the pulse signal is input, and a comparator which compares the drive signal and the output signal of the ring counter and outputs an error signal. The drive circuit for a brushless motor according to claim 5, wherein the drive circuit is configured.