KR100546518B1 - Controller For Brushless DC motor, Control Method, Control Program And Recording Media - Google Patents

Abstract

It is possible to surely start the brushless DC motor while reducing the power consumption.

At start-up of the brushless DC motor, a position holding current is supplied for holding the rotor of the brushless DC motor in a stopped state for a predetermined time, and after stopping supply of the position holding current, the already held position holding current is supplied. By refluxing, the starting current is supplied while the rotor is held in the stopped state by the position holding current flowing through the reflux flow path.

AC power supply, inverter, brushless DC motor, position detection circuit, AC / DC converter

Description

Brushless DC motor, control method, control program and recording media

1 is a schematic configuration block diagram of a brushless DC motor control device of an embodiment;

2 is a timing chart during normal driving.

Fig. 3 is a timing chart at the start control of the first embodiment.

Fig. 4 is a flowchart of processing at the start control of the first embodiment.

5 is an explanatory diagram of a reflux current.

Fig. 6 is a timing chart at the start control of the first embodiment.

Fig. 7 is a flowchart of processing at the start control of the second embodiment.

<Explanation of symbols for the main parts of the drawings>

1: AC power supply part (starting current supply part)

2: AC / DC converter (starting current supply)

3: inverter part (starting current supply part, rotor position holding part)

4: brushless DC motor

5: position detection circuit

6: control circuit (rotor position holding part, reflux flow path forming part)

7: drive circuit (rotor position holding part, reflux flow path forming part)

100: Brushless DC Motor Control System

TU, TV, TW, TX, TY, TZ: Transistor (reflux flow path forming section)

DU, DV, DW, DX, DY, DZ: Diode (reflux flow path forming part)

The present invention relates to a brushless DC motor control apparatus, a control method, a control program and a recording medium, and more particularly, to a technique for reducing the starting current and improving the starting probability of a brushless DC motor used in a compressor of an air conditioner. It is about.

A conventional brushless DC motor control apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 9-327194.

The brushless DC motor control device described in Japanese Patent Laid-Open No. 9-327194 discloses a non-electrical phase (non-electric armature) of a brushless DC motor in order to know the position of the rotor without using magnetic pole position detecting elements such as hall elements. The position of the rotor is detected using the induced voltage generated in the coil), and the energization of the armature coil current of the brushless DC motor is switched based on the position detection detected in this manner. In addition, since the rotor is stopped at the start of the start of the brushless DC motor, no induced voltage is generated. Therefore, the position detection of the rotor cannot be performed and it is necessary to perform synchronous operation or the like.

More specifically, the conventional brushless DC motor control device converts an AC power source into a predetermined DC power source in an AC / DC converter, and switches the DC power source to a switching element of the inverter unit to armature coils of the brushless DC motor. To feed.

In the case of controlling this brushless DC motor, a position detecting circuit is provided, and the position detecting circuit compares the terminal voltage of the brushless DC motor with a reference level, and transmits the position detecting signal of the comparison result to the control circuit (microcomputer). Output

As a result, the control circuit digitally processes the input position detection signal and outputs a drive signal (PWM signal) for switching the armature coil current of the brushless DC motor to the drive circuit of the brushless DC motor, thereby switching the inverter unit. The device was driving.

By the way, in the case where the conventional brushless DC motor is applied to a rotary compressor, when the energization of the brushless DC motor is stopped for a while after the rotary compressor is stopped, the brushless DC motor is reversed by the pressure in the rotary compressor. It may rotate.

Therefore, in order to grasp the energized state of the rotor at restart, when the position holding current for holding the stop position of the rotor is supplied to the brushless DC motor, the position holding current is reduced to reduce power consumption. When the supply is stopped, there is a problem that the brushless DC motor is rotated in reverse and the rotor position is shifted.

In addition, in order to prevent this rotor position shifting, when supplying a position holding current at the time of starting of a brushless DC motor, and shifting to starting current supply, it is connected in series which comprises an inverter. The timing at which both the transistors of the CM0S structure are turned on sometimes occurs. In such a case, a so-called through current flows to destroy the transistor, or the protection circuit operates to fail to start.

It is therefore an object of the present invention to provide a brushless DC motor control apparatus, a control method, a control program, and a recording medium capable of reliably starting a brushless DC motor while reducing power consumption.

In order to solve the above problems, the brushless DC motor control device is a rotor position for supplying a position holding current for holding the rotor of the brushless DC motor for a predetermined time in a stopped state at the start of the brushless DC motor. The rotation by the holding flow path forming portion which forms a reflux flow path for refluxing the supplied position holding current after the supply stop of the position holding current, and the position holding current flowing through the return flow path. And a starting current supply unit for supplying a starting current in a state where the self is held in the stopped state.

According to the above configuration, the rotor position holding part supplies a position holding current to the brushless DC motor for holding the rotor of the brushless DC motor for a predetermined time at the start of the brushless DC motor.

The reflux flow path forming portion forms a reflux flow path for refluxing the already supplied position holding current after the supply stop of the position holding current.

And the starting current supply part supplies a starting current in the state in which the rotor is hold | maintained by the position holding current which flows through a reflux flow path.

In this case, the brushless DC motor is three-phase control, and the rotor position holding portion holds a first holding as the position holding current to hold the rotor in a stationary state in a first phase. A first rotor position holding portion for supplying current and a second holding current as the position holding current for holding the rotor in a stationary state on a second phase different from the first phase; A rotor position holding part may be provided.

In addition, the effective voltage at the time of position holding may be set lower than the effective voltage at the start-up in order to reduce power consumption.

In addition, the effective voltage at the time of position holding may be set by duty control.

In addition, the control method of the brushless DC motor includes a rotor position holding step of supplying a position holding current for holding the rotor of the brushless DC motor in a stopped state for a predetermined time at the start of the brushless DC motor; And a reflux flow path forming step of forming a reflux flow path for refluxing the already supplied position holding current after the supply of the position holding current is stopped, and the rotor is stopped by the position holding current flowing through the reflux flow path. And a startup current supply process for supplying a startup current in a state held in the state.

In this case, the rotor position holding process includes a first rotor position holding process for supplying a first holding current as position holding current to hold the rotor in a stationary state on the first phase, and a first holding position holding process. A second rotor position holding step of supplying a second holding current as the position holding current for holding the rotor in a stationary state in a second phase different from the phase may be provided.

In addition, the effective voltage at the time of position holding may be set lower than the effective voltage at the start-up in order to reduce power consumption.

In addition, the effective voltage at the time of position holding may be set by the duty ratio set by duty control.

In addition, the control program for controlling the brushless DC motor by the computer supplies a position holding current for holding the rotor of the brushless DC motor in the stopped state for a predetermined time at the start of the brushless DC motor, After the supply of the position holding current is stopped, a reflux flow path for refluxing the already supplied position holding current is formed, and the rotor is held in the stopped state by the position holding current flowing through the reflux flow path. It is characterized by supplying a starting current in the state.

In this case, when the position holding current is supplied, a first holding current as the position holding current is supplied to hold the rotor in a stationary state in a first phase, and different from the first phase. The second holding current as the position holding current may be supplied to hold the rotor in a stationary state in a second phase.

In addition, the effective voltage at the time of position holding may be set lower than the effective voltage at the start-up in order to reduce power consumption.

Alternatively, the above control programs may be recorded in a computer-readable recording medium.

EMBODIMENT OF THE INVENTION Next, preferred embodiment of this invention is described with reference to drawings.

[1] first embodiment

1 is a schematic configuration block diagram of a brushless DC motor control device of an embodiment.

The brushless DC motor control system 100 can be broadly divided into an AC power source 1, an AC / DC converter 2, an inverter unit 3, a brushless DC motor 4, and a position detection circuit 5. And a control circuit 6 and a drive circuit 7.

The AC power supply unit 1 supplies AC power to the brushless DC motor control system 100.

The AC / DC converter 2 converts the supplied AC power into AC / DC and supplies it to the inverter unit 3.

The inverter section 3 is provided with transistors TU, TV, TW, TX, TY, TZ as switching elements, and under the control of the control circuit 6 and the drive circuit 7 the AC / DC converter 2 The DC power supplied from the converter is converted into a three-phase drive power and supplied to the brushless DC motor 4.

The brushless DC motor 4 is driven by the supply of three-phase drive power from the inverter unit 3.

The position detection circuit 5 detects the supply state of the three-phase drive power supply, detects the rotor position (not shown) of the brushless DC motor 4 and notifies the control circuit 6.

The control circuit 6 is configured as a so-called microcomputer, and based on a control program stored in a ROM (not shown) by a microprocessor unit (not shown), it is possible to temporarily store various data in a RAM (not shown). Drive control of the brushless DC motor 4 is performed via the drive circuit 7 based on the rotor position notified from the position detection circuit 5.

The drive circuit 7 performs on / off control of the transistors TU, TV, TW, TX, TY, and TZ constituting the inverter unit 3 under the control of the control circuit 6.

First, the outline operation | movement at the time of normal driving of the brushless DC motor 4 of the brushless DC motor control system 100 is demonstrated before description of a specific start control.

The brushless DC motor control system 100 converts the AC power supplied from the AC power supply unit 1 into a predetermined DC power supply by the AC / DC conversion unit 2, and converts the DC power supply to the transistor of the inverter unit 3 ( TU, TV, TW, TX, TY, and TZ are appropriately switched and supplied to the armature coil of the brushless DC motor 4.

In parallel with this, the position detection circuit 5 compares the terminal voltage (chopped induced voltage) of the brushless motor 4 with a reference level, and outputs this comparison result to the control circuit 6 as a position detection signal.

The control circuit 6 digitally processes the input position detection signal, outputs a drive signal (PWM signal) for switching the energization of the armature coil current of the brushless motor 4 to the drive circuit 7, and an inverter unit. The transistors (TU, TV, TW, TX, TY, TZ) of (3) are driven. As a result, the brushless DC motor 4 is driven to rotate at a desired rotational speed.

2 is a timing chart during normal driving.

As shown in Fig. 2, the control circuit 6 turns on the transistor TY on the driving circuit 7 at the time t1, and drives the transistor TW PWM. As a result, the DC power supply supplied from the AC / DC converter 2 to the inverter unit 3 undergoes a pulse width modulation [PWM: for example, a duty ratio of 50% (%)] through the transistor TW. The coil of the brushless DC motor 4 corresponding to the phase flows to the AC / DC converter 2 through the transistor TY while driving the rotor.

Similarly, when the time t2 is reached, the control circuit 6 turns on the transistor TU through the drive circuit 7 and PWM-drives the transistor TY. Thereby, the DC power supply supplied from the AC / DC conversion part 2 to the inverter part 3 flows through the coil of the brushless DC motor 4 corresponded to a UV phase through the transistor TU, and rotates a rotor. While driving, the pulse width modulation PWM is passed through the transistor TY to return to the AC / DC converter 2.

Further, when the time t3 is reached, the control circuit 6 turns on the transistor TZ through the drive circuit 7 and PWM drives the transistor TU. Thereby, while the DC power supply supplied from the AC / DC converter 2 to the inverter unit 3 is pulse width modulated (PWM) via the transistor TU, the brushless DC motor 4 corresponding to the UW phase is provided. Flows through the coil, and returns to the AC / DC converter 2 via the transistor TZ while driving the rotor.

Moreover, when the time t4 is reached, the control circuit 6 turns on the transistor TV through the drive circuit 7 and PWM-drives the transistor TZ. Thereby, the DC power supply supplied from the AC / DC conversion part 2 to the inverter part 3 flows through the coil of the brushless DC motor 4 corresponded to VW via the transistor TV, and rotates a rotor. While driving, the pulse width modulation PWM is performed through the transistor TZ, and the control unit 2 returns to the AC / DC converter 2.

Further, when the time t5 is reached, the control circuit 6 turns on the transistor TX through the drive circuit 7 and PWM-drives the transistor TV. Thereby, while the DC power supply supplied from the AC / DC conversion part 2 to the inverter part 3 is pulse width modulated (PWM) via the transistor TV, the brushless DC motor 4 corresponded to a UV phase. Flows through the coil, and returns to the AC / DC converter 2 via the transistor TX while driving the rotor.

Moreover, when the time t6 is reached, the control circuit 6 turns on the transistor TW via the drive circuit 7 and PWM-drives the transistor TX. Thereby, the DC power supply supplied from the AC / DC conversion part 2 to the inverter part 3 flows through the coil of the brushless DC motor 4 corresponded on UW via transistor TW, and rotates a rotor. While driving, the device returns to the AC / DC converter 2 while performing pulse width modulation PWM through the transistor TX, thereby completing one cycle of driving the brushless DC motor 4.

Then, at time t7, the transistor TY is turned on again through the driving circuit 7, the PWM is driven by the transistor TW, and the same process is repeated below to control the drive of the brushless DC motor 4. Is done.

Next, start control of the brushless DC motor 4 will be described.

3 is a timing chart at the start control of the first embodiment. 4 is a process flowchart at the start control of the first embodiment.

As shown in Fig. 3, the control circuit 6 turns on the transistor TY on the driving circuit 7 at time t11, and drives the transistor TW PWM. As a result, the DC power supplied from the AC / DC converter 2 to the inverter unit 3 is pulse width modulated at the time of fixing the rotor position through the transistor TW [PWM: for example, the duty ratio 25 ( %)] Flows through the coil of the brushless DC motor 4 corresponding to VW, and returns to the AC / DC converter 2 via the transistor TY while driving the rotor. Thereby, the rotor of the brushless DC motor 4 is fixed to a predetermined position (step S1).

When the time t12 is reached, the control circuit 6 turns on the transistor TY through the drive circuit 7 and turns off the transistor TW. As a result, the diode DZ is brought into a conductive state, and the reflux current flows through the coil of the brushless DC motor 4 corresponding to the VW phase through the transistor TY to hold the rotor in a fixed position (step S2). ).

Thereafter, the reflux current flowing through the coil of the brushless DC motor 4 starts to decrease by the resistance component of the motor coil as shown in FIG.

Thus, when the reflux current flowing through the coil of the brushless DC motor 4 reaches a time t13 before the time TLIM at which the minimum current Imin capable of holding the rotor in a fixed position is reached, the control circuit 6 generates a brushless drive circuit ( 7), the transistor TZ is turned on and the transistor TU is PWM driven. Thereby, the DC power supply supplied from the AC / DC converter 2 to the inverter unit 3 is subjected to the brush width DC motor 4 corresponding to the UW while being pulse width modulated (PWM) via the transistor TU. ) And flows back to the AC / DC converter 2 via the transistor TZ while driving the rotor (step S3).

Thereafter, the position detection of the rotor is performed, and the brushless DC motor 34 shifts to normal driving, and after time t13, the brushless DC motor 34 shifts to the normal driving operation as shown after time t3 in FIG. 2 (step S4).

As described above, according to the first embodiment, while the current required to hold the position of the rotor flows as the reflux current, the control is shifted to the start control, so that the positional deviation of the rotor is not caused. You can start up. In addition, since the through current does not flow through the transistor of the CM0S structure constituting the inverter unit when the rotor is fixed in position, it is possible to prevent the transistor from being destroyed or the transistor's protective circuit from starting and failing to start.

In this case, in the PWM control at the time of fixing the position of the rotor, since the control is performed at a duty ratio smaller than the duty ratio in the PWM control at start-up, power consumption can also be reduced.

[2] second embodiment

In the above first embodiment, the position fixing process of the rotor has been performed by only one degree. However, in the case where the rotor is stopped at a mechanically stable position due to the positional relationship of the stator, even if the start control is performed, the starting can be started. When not able to start (energization which cannot start) occurs.

Thus, the second embodiment is an embodiment in which the rotor is fixed to a plurality of different positions in the energization in order to start the brushless DC motor more reliably.

Fig. 6 is a timing chart at the start control of the second embodiment. 7 is a process flowchart at the start control of 2nd Embodiment.

As shown in Fig. 6, the control circuit 6 turns on the transistor TY on the drive circuit 7 at time t21, and drives the transistor TW PWM. As a result, the DC power supplied from the AC / DC converter 2 to the inverter unit 3 is pulse width modulated when the rotor position is fixed via the transistor TW [PWM: for example, duty ratio 5 (%). )], Flowing through the coil of the brushless DC motor 4 corresponding to the VW, and returning to the AC / DC converter 2 via the transistor TY while driving the rotor. Thereby, the rotor of the brushless DC motor 4 is fixed at the first predetermined position, or the rotor is stopped at a position that cannot be started (not rotated), although the rotor is mechanically stable in a positional relationship with the stator. It will be in the state as it is (step S11).

When the time t22 is reached, the control circuit 6 turns on the transistor TU through the drive circuit 7 and PWM-drives the transistor TY. Thereby, the DC power supply supplied from the AC / DC conversion part 2 to the inverter part 3 flows through the coil of the brushless DC motor 4 corresponded to a UV phase through the transistor TU, and rotates a rotor. While driving, a pulse width modulation [PWM: for example, duty ratio 5 (%)] is passed through the transistor TY to return to the AC / DC converter 2.

Thereby, the rotor of the brushless DC motor 4 is fixed to a 2nd predetermined position (step S12). That is, even if the rotor stops at a position where the rotor is mechanically stabilized in a positional relationship with the stator but cannot be started (not rotated) in the step S11, the fixing to the startable position is completed here. .

When the time t23 is reached, the control circuit 6 turns on the transistor TU through the drive circuit 7 and turns off the transistor TY. As a result, the diode DV is brought into a conductive state, and the reflux current flows through the coil of the brushless DC motor 4 corresponding to the UV phase through the transistor TU, and holds the rotor in a fixed position (step). S13).

Thereafter, the reflux current flowing through the coil of the brushless DC motor 4 starts to decrease by the resistance component of the motor coil as shown in FIG.

Therefore, when the voltage of the reflux current flowing through the coil of the brushless DC motor 4 reaches time t24 before the time TLIM which reaches the minimum current Imin which can hold the rotor in the fixed position, the control circuit 6 is brushless. Transistor TV is turned on via drive circuit 7 and PWM is driven by transistor TZ. Thereby, the DC power supply supplied from the AC / DC conversion part 2 to the inverter part 3 flows through the coil of the brushless DC motor 4 corresponded to VW via the transistor TV, and drives a rotor. While returning to the AC / DC converter 2 while performing pulse width modulation PWM through the transistor TZ (step S14).

Thereafter, position detection is performed, and the brushless DC motor 34 shifts to normal driving, and after time t24, shifts to normal driving operation as shown after time t4 in FIG. 2 (step S15).

As described above, according to the second embodiment, it is ensured that the rotor is securely held at a predetermined position, and further, the current required to hold the rotor position is shifted to the start control while the current flows as the reflux current. Therefore, reliable start can be performed without causing the position shift of the rotor. Further, as in the first embodiment, since the through current does not flow through the transistor of the CM0S structure constituting the inverter unit when the rotor is fixed in position, the transistor is prevented from being broken or the protective circuit of the transistor is prevented from starting up. can do.

Also in this case, in PWM control at the time of fixing the position of the rotor, since the control is performed at a duty ratio smaller than the duty ratio in the PW control during normal driving, power consumption can also be reduced.

[3] Modification of Embodiment

In the above description, the case where a brushless DC motor is used for the compressor of the air conditioner has been exemplified, but the present invention is not limited thereto, but is applied to various devices that require start control using a brushless DC motor, for example, a fan motor motor. It is also possible.

In the above description, the control program is stored in a ROM constituting the control circuit, and the processing is performed. However, the control program is stored in a recording medium such as a hard disk, a removable recording medium, an IC card, read out and executed, or the like. It is also possible to configure the control program to be downloaded and executed via a network of.

According to the present invention, it is possible to reliably start the brushless DC motor while reducing the power consumption.

Claims (12)

A rotor position holding part for supplying a position holding current for holding the rotor of the brushless DC motor in a stopped state for a predetermined time at the start of the brushless DC motor; A reflux flow path forming portion for forming a reflux flow path for refluxing the already supplied position holding current after the supply of the position holding current is stopped; And a starting current supply unit for supplying a starting current while the rotor is held in the stopped state by the position holding current flowing through the reflux flow path. 2. The rotor of claim 1, wherein the rotor position holder comprises: a first rotor position holder for supplying a first holding current as the position holding current to hold the rotor in a stationary state on a first; And a second rotor position holding portion for supplying a second holding current as the position holding current for holding the rotor in a stationary state on a second phase different from the first phase. Brush DC motor control unit. The brushless DC motor control device according to claim 1 or 2, wherein an effective voltage at the position holding is set lower than an effective voltage at the start. 4. The brushless DC motor control device according to claim 3, wherein an effective voltage at the time of position holding is set by duty control. A rotor position holding step of supplying a position holding current for holding the rotor of the brushless DC motor in a stopped state for a predetermined time at the start of the brushless DC motor, A reflux flow path forming step of forming a reflux flow path for refluxing the already supplied position holding current after the supply of the position holding current is stopped; And a starting current supplying process for supplying a starting current while the rotor is held in the stopped state by the position holding current flowing through the reflux flow path. 6. The rotor position holding process according to claim 5, wherein the rotor position holding process supplies a first holding current as the position holding current to hold the rotor in a stationary state on a first phase. and, And a second rotor position holding process for supplying a second holding current as the position holding current for holding the rotor in a stationary state different from the first phase. How to control a brushless DC motor. The control method for a brushless DC motor according to claim 5 or 6, wherein an effective voltage at the position holding is set lower than an effective voltage at the start. The control method for a brushless DC motor according to claim 7, wherein the effective voltage at the time of position holding is set by a duty ratio set by duty control. Control program for controlling brushless DC motor by computer, At start-up of the brushless DC motor, a position holding current is supplied to hold the rotor of the brushless DC motor in a stopped state for a predetermined time, After stopping the supply of the position holding current, a reflux flow path for refluxing the already supplied position holding current is formed, And the starting current is supplied while the rotor is held in the stopped state by the position holding current flowing through the reflux flow path. 10. The apparatus of claim 9, wherein when supplying a position holding current, a first holding current as the position holding current is supplied to hold the rotor in a stationary state on a first phase, And a second holding current as the position holding current for holding the rotor in a stationary state on a second phase different from the first phase. The control program according to claim 9 or 10, wherein the effective voltage at the position holding is set lower than the effective voltage at the start. A computer-readable recording medium in which the control program according to claim 9 or 10 is recorded.

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