JPH07147795A - Method for starting brushless motor - Google Patents

Abstract

PURPOSE:To start a brushless motor with reliability regardless of its characteristics, by, after a specified rotor speed is reached, changing the sequence of energization of stator windings, and shifting from synchronized operation to position detection operation wherein the motor is operated based on variation in induced voltage. CONSTITUTION:The terminal voltages 5-a-5-c of a brushless motor 4 is fed to a position detection circuit 6 to detect induced voltage. The detected induced voltage is fed to a microprocessor 7, which in turn calculates the speed of the rotor. After the motor is started when the rotor speed is calculated, the synchronized operation speed is increased to a specified number of rotations. When the number of rotations reaches a specified one, a shift is accomplished from synchronize operation to position detection operation. Based on the signal of the position detection operation, a signal S to change the combination of rotor windings is given to a group 3 of semiconductor switching elements, and thus the brushless motor 4 is started and operated. This performs the first detection of rotor position after the termination of synchronize operation with reliability.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, a conventional technique for starting a brushless motor is described in Japanese Patent Publication No. 55-26793. This publication describes that the stator winding is first energized to position the rotor at a predetermined position, then the predetermined stator winding is energized for a short time to start the motor in a predetermined direction, After that, the position detection operation by the 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 cause
If a sufficient rotation speed of the rotor cannot be obtained, the required induced voltage cannot be obtained, and it is difficult to start the brushless motor.

Further, as described in Japanese Patent Publication No. 59-36520, when the phase difference between the induced voltage and the external synchronizing signal is detected and the phase difference is within a predetermined phase difference, the position is detected from the synchronous operation. With the method of switching to operation, the phase difference cannot be detected until the phase difference between the induced voltage and the external synchronization signal becomes sufficiently small. The phase difference cannot be detected and it is difficult to start the brushless motor.

[0005]

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

The present invention has been made in order to solve the above problems, and is not easily affected by the characteristics of the brushless motor or the constants of the load torque and induced voltage detection circuit, and can be reliably started. Is intended to provide.

[0007]

Therefore, the present invention has a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. Then, a rotating magnetic field is obtained by energizing some of the plurality of stator windings to detect a change in the induced voltage that occurs in the stator windings that are not energized. In a brushless motor starting method in which the stator windings to be energized are sequentially switched based on the following, the rotor in the stopped state is started by the synchronous operation of sequentially switching the energization to the stator windings, and After gradually increasing the energization cycle of the motor and reaching a predetermined rotor speed, the energization sequence to the stator winding is changed, and the synchronous operation is switched to the position detection operation that operates based on the change in the induced voltage. Brushless Which is another way of starting.

Further, the present invention has a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. Fixed to energize some of the stator windings to obtain a rotating magnetic field, detect changes in induced voltage in the stator windings that are not energized, and energize based on this detection signal In the brushless motor starting method in which the child windings are sequentially switched, the rotor in the stopped state is started by the synchronous operation in which the energization of the stator windings is sequentially switched, and the energization cycle of the stator windings is gradually increased. This is a method for starting a brushless motor in which the energization sequence to the stator windings is changed and a synchronous operation is switched to a position detection operation after a predetermined high motor operating current is reached.

Further, the present invention has a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. Fixed to energize some of the stator windings to obtain a rotating magnetic field, detect changes in induced voltage in the stator windings that are not energized, and energize based on this detection signal In the brushless motor starting method in which the child windings are sequentially switched, the rotor in the stopped state is started by the synchronous operation that sequentially switches the energization to the stator windings, and the energization cycle to the stator windings is gradually increased. A method for starting a brushless motor, which changes the energization sequence to the stator windings and switches from synchronous operation to position detection operation after reaching a predetermined rotor speed and a predetermined motor operating current.

Further, the present invention has a rotor having permanent magnets having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. Fixed to energize some of the stator windings to obtain a rotating magnetic field, detect changes in induced voltage in the stator windings that are not energized, and energize based on this detection signal In a brushless motor starting method in which the child windings are sequentially switched, in a synchronous operation in which the rotor in a stopped state is sequentially switched to energize the stator windings, the stator winding is started after a predetermined energizing cycle. The starting method of the brushless motor is to change the energization sequence to the motor to switch from the synchronous operation to the position detection operation.The present invention is to start the rotor in the stopped state by the synchronous operation to reach a predetermined rotor speed, and then to rotate the stator winding. It is intended to switch to the position detecting operation of the supply order from the synchronous operation to skip to.

Alternatively, according to the present invention, after the rotor in a stopped state is started by the synchronous operation to reach a predetermined rotor speed and a predetermined operating current, the energization sequence to the stator winding is skipped. The synchronous operation is switched to the position detection operation.

Further, according to the present invention, the rotor in the stopped state is started by the synchronous operation of a predetermined energization period, and after a predetermined time has passed from the start, the energization sequence to the stator winding is skipped and synchronized. The operation is switched to the position detection operation.

[0013]

In such a brushless motor starting method,
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 energization sequence to the stator windings. The position of the rotor can be reliably detected.

[0014]

【Example】

Embodiment 1 FIG. 1 shows a brushless motor driving device for carrying out the method for starting a brushless motor of the present invention, in the case where the synchronous operation is switched to the position detection operation after the rotor reaches a rotation speed of Ns. It is a block diagram of.

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

The terminal voltages 5a to 5c of the brushless motor 4 are input to the position detection circuit 6 and the induced voltage is detected. The microprocessor 7 calculates the speed of the rotor, determines whether or not the speed of the rotor has reached the number of revolutions Ns, and changes the combination of stator windings to be energized based on the rotational 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 a speed No at time To, the synchronous operation speed is increased to the rotation speed Ns, and the speed Ns is also called the rotation speed. At time Ts, the synchronous operation is switched to the position detection operation.

FIG. 3 shows the sequence of the 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 performs processing (also referred to as microcomputer processing) 17 while increasing the synchronous operation speed. In step 19 (also called microcomputer processing), the sequence of energizing patterns of the stator winding is advanced step by step (synchronous operation continues).

After that, when it is judged in the processing 18 by the microprocessor 7 that the rotation speed is the predetermined speed Ns, the synchronous operation is ended, and in the processing 20 by the microprocessor 7, the energization pattern sequence is advanced by two steps, and the stator winding is transferred. The energization is started (step 21), the first induced voltage is detected in the process 22 by the microprocessor 7, and the synchronous operation is shifted to the position detecting operation (steps 21 to 23, position detecting operation).

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

Rotating magnetic fields M1 to M6 are generated by the energizing patterns 1 to 6, and rotating magnetic fields M2 to M3 indicated by reference numeral 25 in FIG. 5 and rotating magnetic field M3 indicated by reference numeral 26 in FIG.
From M4 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 energization pattern 2 and the position detection operation is performed after the energization pattern 4 in the figure. Energization is switched at every 60 electrical degrees up to the rotating magnetic field M2 that is in the synchronous operation, and when the operation is shifted to the position detection operation, the energization pattern 3 that generates the rotating magnetic field M3 is skipped, and as indicated by reference numeral 27 in FIG. Then, the rotation angle of the rotating magnetic field is advanced by 120 degrees in electrical angle to the energization pattern 4 for generating the rotating magnetic field M4 by two steps, and the detection of the induced voltage is started.

As shown in FIG. 6, by advancing the rotating magnetic field by 120 degrees, the rotating torque of the motor is increased and a sufficient induced voltage can be obtained, so that a reliable position detecting operation can be started. .

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

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

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

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

Each terminal voltage 12a of the brushless motor 11
Through 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 or not the speed of the rotor has reached the number of rotations Ns, and changes the combination of stator windings to be energized based on the rotational position detection signal of the rotor. S is applied to the semiconductor switching element group 10 to start and operate the brushless motor 11.

The motor operating current I is detected by CT15, and the motor operating current I is detected in the microprocessor 14.
It is determined whether s has been reached.

FIG. 8 shows the concept of the method for starting the brushless motor of the second embodiment. Immediately after starting at To, the rotor moves in a state close to a lock, so that the motor operating current is as Io. It shows a relatively large value and decreases as the synchronous operation speed increases.

Further, as the synchronous operating speed increases, the motor operating current also increases after time Ti.
Then, when the motor operating current Is sufficient to obtain the motor torque is reached, the synchronous operation is switched to the position detection operation.

FIG. 4 shows the sequence of the method for starting the brushless motor of the second embodiment. A series of processing is shown in FIG.
After the rotor has been driven, the energizing pattern sequence of the stator winding is advanced step by step while increasing the synchronous operating speed until the motor operating current reaches a predetermined current Is (step S1). 24a,
24b, 24, 25).

After that, when it is judged by the processing (also referred to as a step) 24 by the microprocessor 14 that the predetermined motor operating current Is is reached, the synchronous operation is ended, the energization pattern sequence is advanced by two steps, and the first induced voltage is detected. ,
Transition from synchronous operation to position detection operation (step 26)
Through 27b).

Embodiment 3 In Embodiment 3, after the rotor reaches the number of revolutions Ns and the motor operating current reaches the current value Is,
This is a case where the synchronous operation is switched 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 terminal voltages 12a to 12c of the brushless motor are input to the position detection circuit 13, the induced voltage is detected, and the microprocessor 14 detects the speed of the rotor to determine whether the rotational speed Ns has been reached. At the same time, the motor operating current is detected by CT15, 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 time To, the synchronous operation speed is increased to Ns, and when the motor operation current Is sufficient to obtain the motor torque is reached at the time Ts when the speed becomes Ns, the synchronous operation is restarted. It is to switch to position detection operation.

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

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

Thereafter, in the process 29 by the microprocessor 14, when it is determined that the rotation speed is the predetermined rotation speed Ns,
In the process 30 by the microprocessor 14, it is determined whether the motor operating current has reached the predetermined current Is.

When it is determined that the current is the predetermined current Is, the synchronous operation is terminated, the energization pattern sequence is advanced by two steps in the process 31 by the microprocessor 14, the first induced voltage is detected, and the synchronous operation is changed to the position detection operation. The process moves (steps 29 to 31).

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

By the way, in Embodiments 2 and 3, FIG.
Although the current detector CT15 is provided between the AC power source 8 and the rectifying circuit 9, the rectifying 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 shows the concept of switching from synchronous operation to position detection operation in a predetermined energization cycle after a predetermined time has elapsed.

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

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

[0049]

As described above, according to the present invention, the brushless motor can be started without being affected by the motor characteristics and the load torque state, and it is sufficient when the synchronous operation is switched to the position detection operation. Since a large motor torque can be obtained and a large induced voltage can be obtained, it is possible to reliably perform the first rotor position detection after the end of the synchronous operation.

[0050]

[Brief description of drawings]

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

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

FIG. 3 is a flowchart showing a starting sequence of the first embodiment shown in FIG.

FIG. 4 is a flowchart showing a starting sequence of the second embodiment shown in FIG.

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.

7 is a rotor speed at the time of starting of Example 1. FIG.

FIG. 8 is a motor current at the start of the second embodiment.

FIG. 9 shows induced voltage waveforms at the time of switching to the normal position detection operation and the start position detection operation.

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

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

FIG. 12 is a diagram showing a rotation speed at the time of starting in a preferred fourth embodiment of the method for starting the 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

Claims (4)

[Claims] 1. A rotor having a permanent magnet having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. While energizing some of the stator windings to obtain a rotating magnetic field, the change in induced voltage that occurs in the stator windings that are not energized is detected, and the stator winding that energizes based on this detection signal is detected. In a brushless motor starting method in which the rotors are switched in sequence, the rotor in a stopped state is started by a synchronous operation that sequentially switches energization to the stator windings, gradually increasing the energization cycle to the stator windings A method for starting a brushless motor, characterized in that after the child speed is reached, the energization order to the stator windings is changed to switch from synchronous operation to position detection operation, which operates based on changes in induced voltage. 2. A rotor having a plurality of permanent magnets and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. While energizing some of the stator windings to obtain a rotating magnetic field, the change in induced voltage that occurs in the stator windings that are not energized is detected, and the stator winding that energizes based on this detection signal is detected. In a brushless motor starting method that is sequentially switched, a rotor in a stopped state is started by a synchronous operation that sequentially switches energization to a stator winding, and the energization cycle to the stator winding is gradually increased to a predetermined motor. A method of starting a brushless motor that changes the energization sequence to the stator windings after the operating current is reached and switches from synchronous operation to position detection operation. 3. A rotor having a permanent magnet having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. While energizing some of the stator windings to obtain a rotating magnetic field, the change in induced voltage that occurs in the stator windings that are not energized is detected, and the stator winding that energizes based on this detection signal is detected. In a brushless motor starting method in which the rotors are switched in sequence, the rotor in a stopped state is started by a synchronous operation that sequentially switches energization to the stator windings, gradually increasing the energization cycle to the stator windings A starting method for a brushless motor, in which the energization sequence to the stator windings is changed and the synchronous operation is switched to the position detection operation after reaching the child speed and a predetermined motor operating current. 4. A rotor having a permanent magnet having a plurality of poles, and a plurality of stator windings arranged to give a rotating magnetic field to the rotor when energized. While energizing some of the stator windings to obtain a rotating magnetic field, the change in induced voltage that occurs in the stator windings that are not energized is detected, and the stator winding that energizes based on this detection signal is detected. In the starting method of the brushless motor that is sequentially switched, the rotor in a stopped state is started in a predetermined energization cycle in a synchronous operation in which the energization of the stator winding is sequentially switched, and then the energization order to the stator winding The method of starting a brushless motor is to change from the synchronous operation to the position detection operation.