JP3326256B2 - How to start a brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a change in an induced voltage generated in a stator winding which is not energized by rotation of a rotor having a plurality of permanent magnets, and based on the detected signal, detects a change in the induced voltage. The present invention relates to a method for starting a brushless motor in which a combination of slave windings is changed.

[0002]

2. Description of the Related Art Generally, a technique related to a conventional brushless motor starting method is disclosed in Japanese Patent Publication No. 55-26793. What is described in this publication is to first energize the stator winding to position the rotor at a predetermined position, and then energize the predetermined stator winding for a short time to start the motor in a predetermined direction, Thereafter, a position detection operation using an induced voltage was performed.

However, in this case, when the motor is started in a predetermined direction after the rotor is positioned at a predetermined position, the impedance of the stator winding and the load torque applied to the rotor may cause the motor to start.
If a sufficient rotation speed of the rotor is not obtained, a required induced voltage cannot be obtained, and it is difficult to start the brushless motor.

Further, as described in JP-B-59-36520, when a phase difference between an induced voltage and an external synchronizing signal is detected and the phase difference falls within a predetermined phase difference, position detection from synchronous operation is performed. In the method of switching to the operation, the phase difference cannot be detected until the phase difference between the induced voltage and the external synchronization signal becomes sufficiently small, and the accuracy of the induced voltage is greatly influenced by the constant of the induced voltage detection circuit. The phase difference cannot be detected, making it difficult to start the brushless motor.

[0005]

However, in such a conventional technique, the brushless motor is easily affected by the characteristics and load torque of the brushless motor or the constant of an induced voltage detection circuit, and it is difficult to reliably start the brushless motor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and is less affected by the characteristics of a brushless motor or the constants of a load torque and an induced voltage detection circuit, and can reliably start the brushless motor. It is intended to provide.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention comprises a rotor having a plurality of permanent magnets and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. Then, six kinds of energization patterns for energizing some of the stator windings of the plurality of stator windings are switched in a predetermined order to obtain a rotating magnetic field, and are generated in a non-energized stator winding. In a starting method for starting a brushless motor in which a change in an induced voltage is detected and the energization pattern of a stator winding to be energized is sequentially switched based on the detection signal, a stopped rotor is fixed to a stator winding. The motor is started by the synchronous operation that sequentially switches the energization pattern to the windings. After the energization pattern switching cycle is gradually increased and the rotor rotation speed reaches the predetermined rotor speed, the energization pattern to the stator windings is skipped. And flop, a method of starting a brushless motor for switching to the position sensing operation to operate on the basis of the change of the induced voltage from the synchronous operation.

The present invention also includes a rotor having a plurality of permanent magnets, and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. A switching magnetic field is obtained by switching six kinds of energization patterns for energizing some of the stator windings in a predetermined order, and a change in an induced voltage generated in a non-energized stator winding is detected. Then, in the starting method for starting the brushless motor in which the energization pattern of the stator winding to be energized based on the detection signal is sequentially switched, the energized pattern to the stator winding is changed by stopping the rotor in the stopped state. The motor is started by the synchronous operation that switches sequentially, and after gradually increasing the switching period of the energization pattern and reaching a predetermined motor operation current, the energization pattern to the stator winding is skipped, and the synchronous operation changes the induced voltage. A method of starting a brushless motor for switching to the position sensing operation to operate on the basis of.

The present invention further includes a rotor having a plurality of permanent magnets, and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. 6 to energize some of the stator windings
The type of energization pattern is switched in a predetermined order to obtain a rotating magnetic field, and a change in an induced voltage generated in a non-energized stator winding is detected. In the starting method at the time of starting the brushless motor in which the brushless motor is sequentially switched,
The rotor in the stopped state is started by synchronous operation in which the energization pattern to the stator winding is sequentially switched, and the switching cycle of the energization pattern is gradually increased, and the rotation speed of the rotor reaches a predetermined rotor speed. A method for starting a brushless motor that skips an energization pattern to a stator winding when a predetermined motor operation current is reached and switches from synchronous operation to position detection operation based on a change in induced voltage.

Further, the present invention comprises a rotor having a plurality of permanent magnets, and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. 6 to energize some of the stator windings
The type of energization pattern is switched in a predetermined order to obtain a rotating magnetic field, and a change in an induced voltage generated in a non-energized stator winding is detected. In the starting method at the time of starting the brushless motor that sequentially switches the
After the rotor in the stopped state is started by the synchronous operation that sequentially switches the energization pattern to the stator winding at a predetermined energization cycle, the energization pattern to the stator winding is skipped, and the induced voltage changes from the synchronous operation. The operation is switched to the position detection operation that is operated based on the above.

[0011]

[0012]

[0013]

According to such a method of starting a brushless motor,
The rotor can be started without being affected by the motor characteristics and the load torque state. Furthermore, when switching from synchronous operation to position detection operation, sufficient motor torque can be obtained and the induced voltage can be reliably detected in order to skip the order of energization to the stator windings. Can reliably detect the rotor position.

[0014]

【Example】

Embodiment 1 FIG. 1 shows a brushless motor driving apparatus for carrying out a brushless motor starting method according to the present invention, in which the rotor is switched from synchronous operation to position detection operation after reaching a rotation speed of Ns. FIG.

In FIG. 1, an AC power supply 1 includes a rectifier circuit 2
And a brushless motor 4 via a semiconductor switching element group 3.

Each of the terminal voltages 5a to 5c of the brushless motor 4 is input to a position detecting circuit 6, and an induced voltage is detected. The microprocessor 7 calculates the speed of the rotor, determines whether the speed of the rotor has reached the rotation speed Ns, and changes the combination of the stator windings to be energized based on the rotation position detection signal of the rotor. S is given to the semiconductor switching element group 3 to start and operate the brushless motor 4.

FIG. 7 shows the concept of the starting method in the first embodiment. After starting at the speed No at the time To, the synchronous operation speed is increased to the rotation speed Ns, and the speed Ns is reached. At time Ts, the operation is switched from the synchronous operation to the position detection operation.

FIG. 3 shows a sequence of a starting method in the first embodiment.

A series of processing is performed in the microprocessor 7 shown in FIG. After the rotor is started, until the rotor speed reaches a predetermined speed Ns (steps 16 to 18), the microprocessor 7 increases the synchronous operation speed in a process (also referred to as a microcomputer process) 17 (step 16 to 18). In step 7 (also referred to as microcomputer processing) 19, the energization pattern sequence of the stator winding is advanced by one step (synchronous operation is continued).

Thereafter, when it is determined in the processing 18 by the microprocessor 7 that the rotation speed is the predetermined rotation speed Ns, the synchronous operation is terminated, and in the processing 20 by the microprocessor 7, the energization pattern sequence is advanced by two steps, and The energization is started (step 21), the first induced voltage detection is performed in processing 22 by the microprocessor 7, and the operation shifts from synchronous operation to position detection operation (steps 21 to 23, position detection operation).

FIG. 5 shows the energization patterns of the stator windings during the position detection operation and the synchronous operation, and the energization patterns of 1 to 6 are repeated.

Each of the energizing patterns 1 to 6 generates a rotating magnetic field of M1 to M6, and the rotating magnetic field M2 to M3 indicated by reference numeral 25 in FIG. 5, and the rotating magnetic field M3 indicated by reference numeral 26 in FIG.
To M4, the energization pattern is switched so as to rotate every 60 degrees in electrical angle.

FIG. 6 shows a case where the synchronous operation is performed up to the energizing pattern 2 in the figure and the position detecting operation is performed after the energizing pattern 4. The energization is switched every 60 electrical degrees to the rotating magnetic field M2 during the synchronous operation, and when shifting to the position detection operation, the energizing pattern 3 for generating the rotating magnetic field M3 is skipped, as indicated by reference numeral 27 in FIG. Then, the rotation angle of the rotating magnetic field is advanced by two steps to the energizing pattern 4 for generating the rotating magnetic field M4, which is advanced by 120 electrical degrees, and the detection of the induced voltage is started.

As shown in FIG. 6, when the rotating magnetic field advances by 120 degrees, the rotating torque of the motor increases and a sufficient induced voltage can be obtained, so that a reliable position detection operation can be started. .

FIG. 9 shows induced voltage waveforms generated when the pattern is advanced from the energizing pattern 2 to the energizing pattern 3 in FIG. 5 and when the pattern is advanced from the energizing pattern 2 to the energizing pattern 4 in FIG.

FIG. 9 (1) shows the case of the energizing pattern of FIG. 5 in which the rotating magnetic field rotates 60 degrees in electrical angle, and FIG. 9 (2)
Fig. 9 shows the case of the energization pattern of Fig. 6 in which the rotating magnetic field rotates 120 degrees in electrical angle. Fig. 9 (2) generates a larger induced voltage, and the position can be detected reliably.

Embodiment 2 FIG. 2 shows Embodiment 2 and is a block diagram in a case where the motor operation current is switched to a synchronous operation or a position detection operation after reaching a current value of Is.

In FIG. 2, an AC power supply 8 includes a rectifier circuit 9.
And a brushless motor 11 via a semiconductor switching element group 10.

Each terminal voltage 12a of the brushless motor 11
12 to 12c are input to the position detection circuit 13 and the induced voltage is detected. The microprocessor 14 calculates the speed of the rotor, determines whether the speed of the rotor has reached the rotation speed Ns, and changes the combination of the stator windings to be energized based on the rotation position detection signal of the rotor. S is given to the semiconductor switching element group 10 to start and operate the brushless motor 11.

The motor operating current is detected by CT15, and the microprocessor 14 detects the motor operating current I.
It is determined whether or not s has been reached.

FIG. 8 shows the concept of the method of starting the brushless motor of the second embodiment. Immediately after starting at To, the rotor changes to a state close to the lock state. It shows a relatively large value and decreases as the synchronous operation speed increases.

Further, when the synchronous operation speed increases, the motor operation current also increases as after time T1.
Then, when the motor operation current Is that can sufficiently obtain the motor torque is reached, the operation is switched from the synchronous operation to the position detection operation.

FIG. 4 shows a sequence of a method for starting the brushless motor according to the second embodiment. A series of processing is shown in FIG.
After the rotor is driven, the stator winding energization pattern sequence is advanced by one step while increasing the synchronous operation speed until the motor operation current reaches a predetermined current Is (step). 24a,
24b, 24, 25).

Thereafter, when it is determined in the process (also referred to as step) 24 by the microprocessor 14 that the current is the predetermined motor operation current Is, the synchronous operation is terminated, the energization pattern sequence is advanced by two steps, and the first induced voltage detection is performed. ,
Transition from synchronous operation to position detection operation (step 26)
To 27b).

Embodiment 3 In Embodiment 3, after the rotor reaches the rotation speed Ns and the motor operating current reaches the current value Is,
This is a case where the operation is switched from the synchronous operation to the position detection operation.

The block diagram of the third embodiment is the same as that of the second embodiment, and is as shown in FIG.

The respective terminal voltages 12a to 12c of the brushless motor are input to a position detecting circuit 13, where an induced voltage is detected, and a microprocessor 14 detects the speed of the rotor to determine whether or not the number of rotations has reached Ns. At the same time, the motor operating current is detected by the CT 15 and the microprocessor 14 determines whether the motor operating current has reached Is.

FIG. 10 shows the concept of a method for starting a brushless motor in the third embodiment.

After starting at the speed No at the time To, the synchronous operation speed is increased to Ns. When the motor operation current Is at which the motor torque can be sufficiently obtained at the time Ts at which the speed Ns is reached, the synchronous operation is started. The operation is switched to the position detection operation.

FIG. 11 shows a sequence of a method for starting a brushless motor according to the third embodiment.

A series of processes are executed by the microprocessor 14 shown in FIG. 2. After the rotor is started, until the rotor speed reaches a predetermined speed Ns, the process is synchronized by a process 28 by the microprocessor 14. While increasing the operation speed, the energization pattern sequence of the stator winding is advanced by one step in the process 32 by the microprocessor 14 (steps 28a, 28, 29, 32).

Thereafter, when it is determined in the processing 29 by the microprocessor 14 that the rotation speed is the predetermined rotation speed Ns,
In processing 30 by the microprocessor 14, it is determined whether or not the motor operating current has reached a predetermined current Is.

When it is determined that the current is the predetermined current Is, the synchronous operation is terminated, the sequence of the energization pattern is advanced by two steps in the process 31 by the microprocessor 14, the first induced voltage is detected, and the synchronous operation is switched to the position detection operation. Transition.

Here, when the motor operating current has not reached the predetermined current Is when the predetermined rotor speed Ns is reached, the synchronous operating speed is further increased in the processing 28 by the microprocessor 14. Good (steps 28a, 28, 29, 30, 32). Alternatively, the voltage applied to the motor may be increased without increasing the synchronous operation speed, or both the synchronous operation speed and the motor applied voltage may be increased.

By the way, in Embodiments 2 and 3, FIG.
Is provided between the AC power supply 8 and the rectifier circuit 9, but the rectifier circuit 9 and the semiconductor switching element group 10
Or between the semiconductor switching element group 10 and the motor 11.

Fourth Embodiment FIG. 12 shows a fourth embodiment, and illustrates the concept of switching from synchronous operation to position detection operation in a predetermined energizing cycle after a predetermined time has elapsed.

After starting at a predetermined constant synchronous operation speed Ns, the operation is switched from synchronous operation to position detection operation at a predetermined time Ts.

When the synchronous operation is terminated and the operation is switched to the position detection operation, as in the above-described embodiment, the energization pattern sequence is advanced by two steps to detect the first induced voltage, and the operation shifts from the synchronous operation to the position detection operation. You can do it.

[0049]

As described above, according to the present invention, it is possible to start a brushless motor without being affected by the motor characteristics and the load torque state. In addition to obtaining a high motor torque and a large induced voltage, the first rotor position detection after the end of the synchronous operation can be reliably performed.

[0050]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a preferred embodiment 1 of a method for starting a brushless motor according to the present invention.

FIG. 2 is a block diagram showing a preferred embodiment 2 of a method for starting a brushless motor according to the present invention.

FIG. 3 is a flowchart showing a start sequence of the first embodiment in FIG. 1;

FIG. 4 is a flowchart showing a start-up sequence according to the second embodiment in FIG. 2;

FIG. 5 is a diagram showing an energization pattern and a rotating magnetic field in a synchronous operation and a position detection operation.

FIG. 6 is a diagram showing an energization pattern and a rotating magnetic field when switching from synchronous operation to position detection operation.

FIG. 7 is a rotor speed at the time of starting according to the first embodiment.

FIG. 8 shows a motor current at the time of starting according to the second embodiment.

FIG. 9 is an induced voltage waveform at the time of switching to the position detection operation at the time of the normal position detection operation and at the time of the start.

FIG. 10 is a diagram showing a relationship between a rotation speed at the time of starting and a motor current in a preferred embodiment 3 of the brushless motor starting method of the present invention.

FIG. 11 is a flowchart showing a starting sequence in a preferred embodiment 3 of the brushless motor starting method according to the present invention.

FIG. 12 is a diagram showing a rotation speed at the time of starting in a preferred embodiment 4 of the method for starting a brushless motor of the present invention.

[Explanation of symbols]

 1,8 Power supply 2,9 Rectifier circuit 3,10 Semiconductor switching element group 4,11 Brushless motor 5a, 5b, 5c Motor terminal voltage 12a, 12b, 12c Motor terminal voltage 6,13 Position detection circuit 7,14 Microprocessor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-239186 (JP, A) JP-A-4-295295 (JP, A) JP-A-4-105585 (JP, A) JP-A-4-199 304192 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H02P 6/20 H02P 6/16

Claims (4)

(57) [Claims] 1. A rotor having a plurality of permanent magnets and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. 6 types of current-carrying putters to energize some of the stator windings
The rotating magnetic field is obtained by switching the
Detecting a change in the induced voltage generated in the stator winding is not energized, through the stator windings to be energized based on the detection signal
In the starting method when starting the brushless motor so as to sequentially switch the conductive pattern, the sequentially switching the energization pattern to the stator winding the rotor in a stopped state
After the start-up operation, the switching cycle of the energization pattern is gradually increased , and the rotation speed of the rotor reaches the predetermined rotor speed. Then, the energization pattern to the stator winding is skipped, and the synchronous operation changes the induced voltage. A method for starting a brushless motor, wherein the method is switched to a position detection operation that operates based on a motor. 2. A rotor having a plurality of permanent magnets, and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. 6 types of current-carrying putters to energize some of the stator windings
The rotating magnetic field is obtained by switching the
Detecting a change in the induced voltage generated in the stator winding is not energized, through the stator windings to be energized based on the detection signal
In the starting method when starting the brushless motor so as to sequentially switch the conductive pattern, the sequentially switching the energization pattern to the stator winding the rotor in a stopped state
Start by year operation, after reaching gradually increasing predetermined motor driving current switching cycle of the energization pattern, skips the energization pattern to the stator winding, operated on the basis of the change of the induced voltage from the synchronous operation position A brushless motor starting method characterized by switching to a detection operation. 3. A rotor having a permanent magnet having a plurality of poles, and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. 6 types of current-carrying putters to energize some of the stator windings
The rotating magnetic field is obtained by switching the
Detecting a change in the induced voltage generated in the stator winding is not energized, through the stator windings to be energized based on the detection signal
In the starting method when starting the brushless motor so as to sequentially switch the conductive pattern, the sequentially switching the energization pattern to the stator winding the rotor in a stopped state
Start by year operation, the rotational speed gradually increasing the rotor a switching period of the energization pattern reaches a predetermined motor driving current with reaching the reaching a predetermined rotor speed, the energization pattern to the stator winding A method for starting a brushless motor, characterized by skipping and switching from a synchronous operation to a position detection operation that operates based on a change in an induced voltage. 4. A rotor having a plurality of permanent magnets, and a plurality of stator windings arranged to apply a rotating magnetic field to the rotor when energized. 6 types of current-carrying putters to energize some of the stator windings
The rotating magnetic field is obtained by switching the
Detecting a change in the induced voltage generated in the stator winding is not energized, through the stator windings to be energized based on the detection signal
In the starting method at the time of starting the brushless motor in which the electric patterns are sequentially switched, the energized pattern to the stator windings is set to a predetermined energized cycle by stopping the rotor in the stopped state.
A method for starting a brushless motor, characterized in that, after being started by synchronous operation in which switching is performed sequentially , a current supply pattern to a stator winding is skipped, and the synchronous operation is switched to a position detection operation in which operation is performed based on a change in an induced voltage. .