JP2722750B2 - Drive device for brushless motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and in particular, detects a relative position between a magnet rotor and an armature winding based on an induced voltage induced in an armature winding to rotate the motor. The present invention relates to a brushless motor driving device that smoothly shifts from a synchronous operation mode to a rotor position detection operation mode without a child magnetic pole position detector.

2. Description of the Related Art A brushless motor usually requires a detector for detecting the magnetic pole position of its rotor. Since the reliability of the detector cannot be guaranteed, these detectors cannot be used. Therefore, in such an application, a method is used in which a voltage signal induced in an armature winding is detected without using a magnetic pole position detector, and a commutation signal of a motor is generated based on the voltage signal.

However, a voltage signal is induced in the armature winding only when the rotor is rotating. When the rotor is stopped, magnetic pole position information cannot be obtained. That is, this voltage signal cannot be used at the time of startup. Therefore, at the time of startup, a specific signal for generating a rotating magnetic field is given to the armature winding regardless of the magnetic pole position of the rotor, and the rotor is forcibly rotated.

Thereafter, when the rotor starts to rotate, a voltage signal induced in the armature winding is detected, and a commutation signal of the motor can be generated based on the detected voltage signal. Thus, the method of driving the brushless motor is started by the synchronous operation, and is later switched to the rotor position detection operation. Adjustment of the voltage supplied to the motor uses so-called pulse width modulation in which the DC power supply voltage is kept constant and the voltage is controlled by controlling the duty ratio of the voltage signal pulse.

Various methods have been devised for switching between the synchronous operation mode and the rotor position detection operation mode. However, it is difficult to make a transition while maintaining a stable operation state, and mechanical vibration is generated. Or the instantaneous increase of the drive current, which causes a load on the semiconductor switching element for driving the motor.

The present invention has been made in view of the above-mentioned conventional problems, and by appropriately setting the rotation speed, the duty ratio in the synchronous operation mode, and the duty ratio in the rotor position detection operation mode, the synchronous operation mode can be changed to the rotor position detection operation mode. The purpose of this is to make the switching smoothly.

Means for Solving the Problems In order to achieve the above object, the present invention relates to a method in which the relationship between the rotation speed in the synchronous operation mode and the rotation speed in the rotor position detection operation mode is set such that the rotation speed in the rotor position detection operation mode is the synchronous operation mode. Is provided with a configuration that is equal to or lower than the number of rotations.

That is, a brushless motor having a three-phase armature winding connected to a neutral point non-ground, a DC power supply, a semiconductor switching element group for energizing and interrupting a current to the armature winding, and a magnet rotor. Starting command means, synchronizing signal generating means for outputting a synchronizing signal in accordance with the command of the starting command means, and a rotating magnetic field for generating a rotating magnetic field in the armature winding using a signal output from the synchronizing signal generating means Generating means, position detecting means for detecting a relative position between the armature winding and the magnet rotor based on a voltage signal induced in the armature winding, an output signal from the rotating magnetic field generating means, and the position detection. Switching means for selecting, switching and outputting an output signal of the switching means, switching instruction means for giving a switching instruction to the switching means, and a drive signal for the switching element group using an output signal of the switching means. A drive signal generating means for generating a duty ratio command means; a pulse width modulation means for performing pulse width modulation on an output signal of the drive signal generating means based on a command from the duty ratio command means; After the command is issued, the frequency of the output signal of the synchronization signal generating means and the duty ratio command are output, and the magnet rotor is started to rotate. After the start, the switching means is switched to switch the position detecting means. A configuration is provided for driving the brushless motor based on the output signal.

In the rotor position detection mode, the rotation speed is determined by the motor characteristics and the load state with respect to the given duty ratio. However, according to the above-described configuration, the rotation speed in the synchronous operation mode and the rotation speed in the rotor position detection operation mode The relationship between the number of rotations, the duty ratio in the synchronous operation mode, and the duty ratio in the rotor position detection operation mode is such that the rotation speed in the rotor position detection operation mode is equal to or lower than the rotation speed in the synchronous operation mode. , The switching from the synchronous operation mode to the rotor position detection operation mode is smoothly performed.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of a brushless motor starting device according to an embodiment of the present invention. In FIG. 2, reference numeral 1 denotes a DC power supply, and 2 denotes a semiconductor switching element group comprising six transistors Q1 to Q6 and six diodes respectively connected in antiparallel. Reference numeral 3 denotes an armature winding 4 and a magnet rotor 5 connected in a three-phase manner by a brushless motor. 6 is a position detecting means, 7 is a switching means, 8 is a driving signal generating means, 9 is a pulse width modulating means, 10 is a synchronizing signal generating means, 11 is a rotating magnetic field generating means, 12 is a start command means, and 13 is a switching command means. , 14 are duty ratio command means.

With the above configuration, at the time of startup, the output signal of the rotating magnetic field generating means 11 is transmitted to the drive signal generating means 8 by the switching means 7, and the output signal is subjected to pulse width modulation set for the synchronous operation mode to apply the semiconductor switching element. The transistors of the group 2 are driven to start the brushless motor 3. When the brushless motor 3 starts rotating, the position detection means 6 detects the magnetic pole position of the magnet rotor 5 from the induced voltage generated in the armature winding 4, and the switching means 7 sends the signal to the drive signal generation means 8. Then, the transistor of the semiconductor switching element group 2 is driven by applying pulse width modulation set for the rotor position detection mode to the brushless motor 3.
Is controlled.

FIG. 3 shows a more specific configuration of the block diagram of FIG. 2, and the same components as those in FIG. 2 or those having the same functions are denoted by the same reference numerals.

In this figure, 1 to 5 are exactly the same as in FIG. 6
Is a position detection circuit comprising three filters 61 to 63 and a comparator group 64. 7 is a switching circuit, 8 is a drive signal generation circuit,
9 is a pulse width modulation circuit, 10 is a synchronization signal generation circuit, 11 is a rotating magnetic field generation circuit, 13 is a switching command circuit, and 15 is a microcomputer corresponding to the start command means 12 and the duty ratio command means 14 in FIG. Start command signal 15 to synchronous signal generation circuit 10
1 and the duty ratio command signal 153 to the pulse width modulation circuit 9 respectively.

The operation of the embodiment of the brushless motor driving device configured as described above will be described.

First, the microcomputer 15 starts the start command signal 15
1. The switching signal 152 and the duty ratio command signal 153 are output simultaneously. Synchronous signal generation circuit 1 that has received start command signal 151
0 outputs a synchronization signal 100 as shown in FIG. On the basis of the synchronization signal 100, the rotating magnetic field generation circuit 11 outputs signals 111 to 113 shown in FIG. The switching circuit 7 switches between the input signals 87 to 89 of the drive signal generation circuit 8 and the output signal of the position detection circuit 6 or the output signal of the rotating magnetic field generation circuit 11. The signal is switched to the output signal side of the rotating magnetic field generation circuit 11 by 152.
Output signals 111 to 113 of the rotating magnetic field generation circuit 11 are taken into the drive signal generation circuit 8, and output from the circuit 81 to 113 shown in FIG.
Outputs 86 output signals. Of these output signals, 81 to
83 is further input to the pulse width modulation circuit 9 and pulse width modulation is performed based on the duty ratio command signal 153 set for the synchronous operation mode, and drive signals for the transistors Q1 to Q3 of the semiconductor switching element group 2 are respectively provided. Becomes On the other hand, the output signals 84 to 86 of the drive signal generating circuit 8 are directly used as the transistors Q4 to Q4 of the semiconductor switching element group 2.
It becomes the drive signal of Q6. The six transistors of the semiconductor switching element group 2 are switched by these drive signals. As a result, a rotating magnetic field is generated in the armature winding 4, and the magnet rotor 5 rotates to start the brushless motor 3. Become.

Here, simultaneously with the rise of the start command signal 151, the synchronous signal 100 and the duty ratio command signal 153 set for the synchronous operation mode are output, and the brushless motor rotates.

After startup, the switching command circuit 13 outputs a switching signal 152,
The switching circuit 7 is switched to the position detection circuit 6 side. Thus, the input signals 87 to 89 of the drive signal generation circuit 8 become the output signals 641 to 643 of the position detection circuit 6, and the brushless motor 3 is driven by the induced voltage signals 41 to 43 generated in the armature winding 4 thereafter. Becomes Further, the microcomputer 15 simultaneously outputs a duty ratio command signal set for the rotor position detection operation mode by the switching signal 152. Following the fall of the switching signal 152, the activation command signal 151 is released, and a series of activation operation procedures are reset to the initial state.

The synchronous signal 100 and the duty ratio in the synchronous operation mode are set so that the rotational speed when shifting from the synchronous operation mode to the rotor position detection operation mode in the series of operations is equal to or lower than the rotational speed in the synchronous operation mode. Command signal 153,
And a duty ratio command signal 153 in the rotor position detection operation mode. Explaining with reference to FIG. 1, in the synchronous operation mode, startup is performed with the rotation speed r0 and the duty ratio d0. This is set in consideration of the motor specifications, load conditions, and restrictions such as the allowable current value of the semiconductor switching element group.In the rotor position detection operation mode, the duty ratio is set to d1 and the rotation speed r1 is set. r1 ≦ r0. This operation realizes smooth switching from the synchronous operation mode to the rotor position detection operation mode. For example, if the duty ratio in the rotor position detection operation mode is set to d2, the number of rotations r2 will be r2> r0, and rapid acceleration will occur when shifting to the rotor position detection operation mode, making it impossible to expect smooth mode switching. .

Note that the duty ratio command signal 153 is output from the microcomputer 15 as an applied voltage control command for controlling the speed of the brushless motor 3 in the rotor position detection operation mode.

In the embodiment, the synchronizing signal generation circuit 10, the rotating magnetic field generation circuit 11, and the switching command circuit 13 are each a single circuit. However, the microcomputer 15 may perform a part or all of these circuit functions.

Advantageous Effects of the Invention As described above, the present invention provides a three-wire connection with a neutral point and no ground.
Phase armature winding, a DC power supply, a semiconductor switching element group for energizing and interrupting a current to the armature winding, a brushless motor having a magnet rotor, start command means, and a command for the start command means. A synchronous signal generating means for outputting a synchronous signal, a rotating magnetic field generating means for generating a rotating magnetic field in the armature winding using a signal output from the synchronous signal generating means, Position detecting means for detecting a relative position of the armature winding and the magnet rotor by a voltage signal, and an output signal of the rotating magnetic field generating means and an output signal of the position detecting means are selected, switched and output. Switching means, switching command means for giving a switching command to the switching means, drive signal generating means for generating a drive signal for the switching element group using an output signal of the switching means, And a pulse width modulation means for applying pulse width modulation to an output signal of the drive signal generation means based on a command of the duty ratio command means. By setting the duty ratio of the operation mode and the duty ratio of the rotor position detection operation mode such that the rotation speed of the rotor position detection operation mode is the same as or lower than the rotation speed of the synchronous operation mode, the rotor is switched from the synchronous operation mode. Switching to the position detection operation mode can be performed smoothly.

[Brief description of the drawings]

FIG. 1 is a waveform diagram showing the relationship between the rotational speed and the duty ratio in the synchronous operation mode and the rotor position detection operation mode of the brushless motor driving device according to the embodiment of the present invention, and FIG. FIG. 3 is a block diagram of a brushless motor driving device specifically constructed from FIG. 2, and FIG. 4 is a waveform diagram of each part in the block diagram of FIG. 1 DC power supply 2 Semiconductor switching element group 3
... brushless motor, 4 ... armature winding, 5 ... magnet rotor, 6 ... position detecting means, 7 ... switching means, 8 ...
Drive signal generating means, 9 pulse width modulating means, 10 synchronous signal generating means, 100 synchronous signal, 11 rotating magnetic field generating means, 12 start command means, 13 switching command means, 14
... Duty ratio command means, 15 ... microcomputer, 151 ... start command signal, 152 ... switching signal, 153 ...
Duty ratio command signal.

Claims (1)

(57) [Claims] 1. A three-phase armature winding connected to a neutral point non-ground, a DC power supply, and a current flowing to the three-phase armature winding.
A semiconductor switching element group to be cut off, a brushless motor having a magnet rotor, a start command unit, a synchronous signal generating unit for outputting a synchronous signal according to a command of the start command unit, and a signal output from the synchronous signal generating unit A rotating magnetic field generating means for generating a rotating magnetic field in the three-phase armature winding using the three-phase armature winding, and a relative position between the three-phase armature winding and the magnet rotor by a voltage signal induced in the three-phase armature winding. Position detecting means for detecting a target position, switching means for selecting and switching and outputting an output signal of the rotating magnetic field generating means and an output signal of the position detecting means, switching command means for giving a switching command to the switching means, A drive signal generating means for generating a drive signal for the switching element group using an output signal of the switching means, a duty ratio commanding means, and an output signal of the drive signal generating means. Pulse width modulation means for performing pulse width modulation based on a command from the duty ratio command means, wherein the duty ratio command means rotates the relationship between the rotation speed in the synchronous operation mode and the rotation speed in the rotor position detection operation mode. A driving device for a brushless motor, wherein the driving is performed such that the rotation speed in the slave position detection operation mode is equal to or lower than the rotation speed in the synchronous operation mode.