JPH0984383A - Brushless motor drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a stable operation of a motor by making equal the number of pulses in each power feeding period and eliminating error of the voltage applied to a motor. SOLUTION: In a brushless motor wherein the change of induced voltage on a stator coil to which the power is not fed is detected and combination of stator coils, to which power is applied by providing adequate delay time from the time when such detected signal can be obtained, is sequentially switched, when rotor position is detected from the induced voltage generated on the stator coils and combination of stator coils to be fed is changed from the detected signal obtained, phase of pulse width modulation for adjusting the voltage applied to the motor is synchronized with the timing for changing the combination of the stator coils.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter operation of a compressor such as an air conditioner or a refrigerator, and more particularly to a method of operating a brushless motor which is position-detected by an induced voltage.

[0002]

2. Description of the Related Art In a brushless motor, a combination of stator windings to be energized is changed based on a change in induced voltage generated in a stator winding not energized by rotation of a rotor having a plurality of permanent magnets. , The stator winding is energized intermittently by PWM or the like, and in accordance with this interruption, a continuous change in the induced voltage calculated based on digital data obtained by A / D conversion of the induced voltage and a predetermined change Japanese Patent Application Laid-Open No. 3-82391 discloses a device that detects the rotational position of a rotor based on the magnitude of the DC voltage.

In the invention described in the above publication, the phase of the pulse width modulation for adjusting the voltage applied to the brushless motor is controlled by continuing the phase determined at the start of energization of the motor. However, in this case, when capturing the energizing section in units of energizing combinations to the stator windings,
There was an error in the number of pulses in each section.

This will be described with reference to FIG. FIG. 2 shows the timing when the PWM signal is generated in a constant cycle and the timing of the energized phase when energizing the phase of each motor. For example, in section 1, U phase and W
It is shown that the phases are energized and the phases are energized from the U phase to the W phase. If it is section 2, from W phase to V phase, W in the same way
It is shown that current is supplied from the phase to the V phase, from the W phase to the U phase, and from the V phase to the U phase. In the section 1, the current is substantially energized by the PWM for 4 pulse periods. On the other hand, in section 2 3
It becomes a part of energization period of the pulse part and the fourth pulse, and the section 3
Then, it becomes a part of energization period of the third pulse and the fourth pulse.
In this way, when PWM is applied to the energized phase to the motor for voltage adjustment, the number of pulses does not necessarily become the same in each section. This error directly becomes the difference in the voltage applied to the motor, which is a factor that hinders stable operation of the motor.

[0005]

SUMMARY OF THE INVENTION According to the present invention, in a brushless motor for intermittently energizing a stator winding by PWM or the like, the number of pulses in each energizing period is made equal to eliminate an error in a voltage applied to the motor. In addition, the pulse generation is set to a desired state to achieve stable operation of the motor.

[0006]

The invention according to claim 1 of the present invention is a combination of stator windings for detecting a rotor position from an induced voltage generated in the stator winding and energizing from the obtained detection signal. The phase of the pulse width modulation for adjusting the voltage applied to the motor is corrected in synchronism with the time of changing the voltage.
In such a brushless motor, from one energization switching to the next energization switching is one section,
The voltage applied to the motor in each section can be made constant.

According to the second aspect of the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and the combination of the stator windings to be energized is changed from the obtained detection signal in synchronization with the time. When the phase of the pulse width modulation for adjusting the voltage applied to the motor is corrected, it is synchronized with the ON state of the pulse width modulation pulse. In such a brushless motor, a reliable driving force can be obtained because the state immediately after the energization is switched by energization switching starts from ON.

According to a third aspect of the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and the combination of stator windings to be energized is changed from the obtained detection signal in synchronization with the time. Thus, when the phase of the pulse width modulation for adjusting the voltage applied to the motor is corrected, it is particularly synchronized with the OFF state of the pulse width modulation pulse. In such a brushless motor, it ends in the ON state even before the energization switching, and remains in the ON state immediately after the energization switching.
When the state becomes long, a certain OFF state can be obtained in the case where inconvenience occurs.

According to a fourth aspect of the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and the combination of the stator windings to be energized is changed from the obtained detection signal at the motor The voltage is corrected so as to be synchronized with the phase of pulse width modulation for adjusting the applied voltage. In such a brushless motor, it is possible to make the voltage applied to the motor constant in each section by defining one section from one energization switching to the next energization switching as one section. Further, since the phase of pulse width modulation does not change, it is possible to avoid overlapping of ON states and OFF states due to switching of energization sections.

According to a fifth aspect of the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and the combination of the stator windings to be energized is changed from the obtained detection signal at the motor When the pulse width modulation phase for adjusting the applied voltage is synchronized with the ON state of the pulse width modulation pulse. In such a brushless motor, a reliable driving force can be obtained because the state immediately after switching the energization by the energization switching starts from ON.

According to a sixth aspect of the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and the combination of the stator windings to be energized is changed from the obtained detection signal at the motor position. When synchronizing with the phase of pulse width modulation that adjusts the applied voltage of
It is synchronized with the state. In such a brushless motor, the state immediately after the energization is switched by energization switching starts from OFF. Due to this, when the energization switching is finished in the ON state, and immediately after the energization switching is also in the ON state, the ON state becomes long,
A reliable OFF state can be obtained when inconvenience occurs.

[0012]

1 is a block diagram showing the configuration of the present invention. 1 is an AC power supply, 2 is a rectifier circuit, 3 is a semiconductor switching circuit, 4 is a brushless motor, 5 is a position detection circuit, and 6 is a microprocessor. The position detection circuit 5 detects the rotor position based on the change in the induced voltage of the motor, and the microprocessor 6 based on the detected position signal.
In the signal at which the energization of the stator winding was sequentially switched,
A composite signal of pulse width modulation signals for adjusting the voltage applied to the motor is generated, and the semiconductor switching circuit 3 is controlled.

According to the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and the voltage applied to the motor is changed when the combination of the stator windings to be energized is switched from the obtained position signal. The phase of the pulse width modulation to be adjusted is synchronized with the combination switching timing of the stator windings, or the switching timing is synchronized with the phase of the pulse width modulation for adjusting the voltage applied to the motor.

3 to 6, the vertical axis represents the timing of generation of the PWM signal according to the present invention and the timing of the energized phase when energizing the phases of the respective motors. The energization section of is shown on the horizontal axis. For example, section 1 indicates that the U-phase and the W-phase are energized, and the U-phase is energized toward the W-phase. In the section 2, the U-phase is energized to the V-phase, similarly, the W-phase is sequentially energized to the V-phase, the W-phase is energized to the U-phase, and the V-phase is energized to the U-phase. Next, the synchronous relationship between the phase of pulse width modulation for adjusting the voltage applied to the motor and the combination switching timing of the stator windings is shown in each figure.

FIG. 3 shows a case where the rising of the ON state is synchronized with the switching of the energized phase in the PWM timing, and the number of PWN pulses in each section is equal.
In such a brushless motor, the state immediately after switching the energization starts from ON, so that a reliable driving force can be obtained.

FIG. 4 shows a case in which the timing of the pulse OFF timing is synchronized with the switching of the energized phase, including the fall of the ON state (start of the OFF state) within the PWM timing. The number of PWM pulses becomes equal. In such a brushless motor,
A reliable OFF state can be obtained in the case where there is a problem when the ON state ends even before the energization switching and the ON state becomes long immediately after the energization switching as well.

In FIG. 5, the PWM timing remains the same, and conversely, the switching of the phase energization is switched to O in the PWM timing.
The figure shows the case of synchronizing with the N state. In such a brushless motor, a reliable driving force can be obtained because the state immediately after switching the energization by the energization switching starts from ON.

In FIG. 6, the PWM timing remains unchanged, and the switching of the phase energization is turned off within the PWM timing.
It shows the case of synchronizing with the state. The switching of the energized phase should be synchronized with any time of PWM. In such a brushless motor, the state immediately after the energization is switched by energization switching starts from OFF. As a result, even if the energization is switched on, the operation is completed in the ON state, and immediately after energization switching, the ON state is maintained.
The state is obtained.

[0019]

As described above, according to the present invention, the rotor position is detected from the induced voltage generated in the stator winding, and when the combination of the stator windings to be energized is switched from the obtained position signal, the motor position is changed. Disadvantages of the conventional method by synchronizing the pulse width modulation phase that adjusts the applied voltage with the combination switching timing of the stator windings, or by synchronizing the switching timing with the pulse width modulation phase that adjusts the applied voltage to the motor The phase of the pulse width modulation that adjusts the voltage applied to the brushless motor was maintained at the phase that was determined at the start of energization of the motor, and an error occurred in the number of pulses in each energization section, stabilizing the motor. It is possible to avoid hindering driving. Moreover, a reliable driving force and a desired operating state can be realized.

[Brief description of drawings]

FIG. 1 is an operation control block diagram of a brushless motor according to the present invention.

FIG. 2 is a diagram illustrating a relationship between a PWM signal generation timing, a conduction phase timing, and a conduction section according to a conventional example.

FIG. 3 is a diagram showing a relationship between a PWM signal generation timing and a conduction phase timing and a conduction section according to the embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a PWM signal generation timing and a conduction phase timing and a conduction section according to another embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a PWM signal generation timing and a conduction phase timing and a conduction section according to another embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a PWM signal generation timing and a conduction phase timing and a conduction section according to another embodiment of the present invention.

[Explanation of symbols]

 1 ... AC power supply 2 ... Rectifier circuit 3 ... Semiconductor switching circuit 4 ... Brushless motor 5 ... Position detection circuit 6 ... Microprocessor

Claims (6)

[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. Some of the stator windings are energized to obtain a rotating magnetic field, and changes in the induced voltage that occur in the stator windings that are not energized are detected. In a brushless motor configured to sequentially switch the combination of stator windings that energize for a certain period of time,
The rotor position is detected from the induced voltage generated in the stator winding,
A brushless motor characterized by synchronizing the phase of pulse width modulation for adjusting the voltage applied to the motor with the combination switching timing of the stator windings when switching the combination of the stator windings that are energized from the obtained position signals. Driving method. 2. The method of operating a brushless motor according to claim 1, wherein the synchronization is synchronized with an ON timing of a pulse width modulation pulse. 3. The synchronization is turned off by a pulse width modulation pulse.
The method of operating a brushless motor according to claim 1, wherein the brushless motors are synchronized at timing. 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. Some of the stator windings are energized to obtain a rotating magnetic field, and changes in the induced voltage that occur in the stator windings that are not energized are detected. In a brushless motor configured to sequentially switch the combination of stator windings that energize for a certain period of time,
The rotor position is detected from the induced voltage generated in the stator winding,
A method for operating a brushless motor, characterized in that, when a combination of stator windings to be energized is switched from the obtained position signal, the switching timing is synchronized with a phase of pulse width modulation for adjusting a voltage applied to the motor. 5. The method of operating a brushless motor according to claim 4, wherein the synchronization is synchronized with an ON timing of a pulse width modulation pulse. 6. The pulse width modulation pulse is turned off by the synchronization.
The method of operating a brushless motor according to claim 4, wherein the operation is synchronized with the timing.