JPH04261388A - Starting method of brushless motor - Google Patents

Abstract

PURPOSE:To realize smooth transition of mode in a short time by lowering acceleration rate for a predetermined time immediately before transition from synchronous operation mode to rotor position detecting operation mode. CONSTITUTION:Under rotor position detecting operation mode, voltage signals U-W induced in the armature winding 4 of a brushless motor 3 having a magnet rotor 5 are detected and converted through a rotor position detecting means 6 thus obtaining rotor position detection signals 6U-6W. A motor 3 is operated based on produced commutation signals 7U-7W. Under synchronous operation mode, a rotary field is generated based on commutation signals created from external signals before the signals 6U-6W are established thus operating and accelerating the motor 3 forcibly. Acceleration rate in the synchronous operation is lowered during a predetermined interval immediately before transition from the synchronous operation mode to the rotor position detecting operation mode thus accelerating the motor slowly. According to the invention, the rotor position detection signal is established stably thus bringing about a state sufficient for mode transition.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method of starting a brushless motor used in a compressor motor of an air conditioner, and in particular, to a method for starting a brushless motor used in a compressor motor of an air conditioner, and in particular, a method for starting a brushless motor used in a compressor motor of an air conditioner. The present invention relates to a method for starting a brushless motor that detects a target position and operates based on this position detection signal.

0002

2. Description of the Related Art Brushless motors usually require a detector for detecting the magnetic pole position of the rotor. By the way, in cases where it is difficult to use this magnetic pole position detector, such as in the compressor motor of an air conditioner that is placed under high temperature and high pressure conditions, the magnetic pole position detector can be omitted and the voltage induced in the armature winding can be measured. A method is used in which a motor commutation signal is generated based on the signal.

That is, a brushless motor generally has an armature winding and a magnet rotor, and detects a voltage signal induced in the armature winding and converts it into a rotor position detection signal, and detects the rotor position. The brushless motor is rotated by a commutation signal generated from the detection signal. Such an operation mode is called a rotor position detection operation mode.

On the other hand, when the brushless motor is stopped, no induced voltage is generated in the armature winding, so the brushless motor is forced to rotate at a low speed by a low-frequency commutation signal generated from an external signal. ing. Such an operation mode is called a synchronous operation mode.

[0005] Once the rotor position detection signal is established in the synchronous operation mode, at that point the signal source of the commutation signal is switched to the rotor position detection signal, and the mode shifts to the rotor position detection mode.

FIG. 4 shows a conventional example of a change in the rotational speed of the motor when transitioning from the synchronous operation mode to the rotor position detection mode. As shown in the figure, conventionally, the acceleration rate of the motor during synchronous operation is constant.

[0007]

[Problems to be Solved by the Invention] However, in the synchronous operation mode, since the brushless motor is forced to operate, the behavior is unstable, and this is particularly noticeable during acceleration. When the synchronous operation mode is shifted to the rotor position detection operation mode in such an accelerated state, the state changes significantly, and as a result, there is a problem in that the mode shift may fail. In order to solve this problem, a method has been devised to provide a constant speed period just before transitioning to the rotor position detection operation mode, but when this is applied to the compressor motor of an air conditioner, the compressor motor does not reach a predetermined speed. The problem is that it takes a long time to accelerate to the point where the air conditioner starts up, and the start-up performance of the air conditioner deteriorates.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a method for starting a brushless motor that allows a smooth mode transition from a synchronous operation mode to a rotor position detection operation mode in a short period of time. It is.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the present invention detects a voltage signal induced in the armature winding of a brushless motor having a magnetic rotor, and uses this voltage signal to detect the rotor position. a rotor position detection operation mode in which the brushless motor is operated by a commutation signal generated from the rotor position detection signal, and a rotor position detection operation mode in which the rotor position detection signal is converted into a rotor position detection signal by means of a rotor position detection signal; The brushless motor has a synchronous operation mode in which a rotating magnetic field is generated by a commutation signal generated from an external signal to forcibly operate and accelerate the brushless motor, and the synchronous operation mode shifts to a rotor position detection operation mode. This is to reduce the acceleration rate of the synchronous operation during the immediately preceding fixed period.

0010

[Operation] By doing so, the present invention reduces the acceleration rate at the time of transition from the synchronous operation mode to the rotor position detection operation mode, thereby increasing stability and allowing a smooth mode transition in a short time.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a configuration diagram of a brushless motor driving device according to an embodiment of the present invention, and 1 is a DC power supply. 2
is a group of semiconductor switching elements, which consists of six transistors U to Z and six diodes connected in antiparallel to each transistor. Reference numeral 3 designates a brushless motor, which includes an armature winding 4 and a magnet rotor 5 connected in three phases. Reference numeral 6 denotes rotor position detecting means, which includes three filters 61 to 63 and a comparator group 64. Reference numeral 7 denotes a microcomputer as a commutation signal generating means, which performs logical operations on the rotor position detection signals 6U, 6V, and 6W output from the rotor position detection means 6 to perform commutation of the transistors of the semiconductor switching element group 2. Generate signals 7U to 7Z, respectively U
~ Switch six transistors of Z.

The operation of the brushless motor operating device constructed as above will be explained. First, in the rotor position detection operation mode, voltage signals U to W induced in the armature winding 4 are detected, and these voltage signals are converted into rotor position detection signals 6U to 6W by the rotor position detection means 6. . The brushless motor 3 is driven by commutation signals 7U to 7Z generated from the rotor position detection signals 6U to 6W. That is, in this rotor position detection operation mode, the rotor position detection signals 6U to 6W shown in FIG. 3 are taken into the commutation signal generating means 7, and logical operations are performed to generate commutation signals 7U to 7Z. These commutation signals 7U~7
Z causes the transistors of the semiconductor switching element group 2 to be switched, causing the brushless motor 3 to continuously generate rotational torque.

On the other hand, when the brushless motor 3 is stopped, no induced voltage is generated in the armature winding 4. For this reason,
At startup, the brushless motor 3 is forcibly rotated at a low speed by applying the commutation signals 7U to 7Z of FIG. 3 at a low frequency from the outside to generate a rotating magnetic field. This rotation generates an induced voltage in the armature winding 4, which is converted by the rotor position detection means 6 to obtain rotor position detection signals 6U to 6W shown in the figure. The above is the synchronous operation mode.

When the rotor position detection signal is established in the synchronous operation mode, switch the signal sources of the commutation signals 7U to 7Z to the rotor position detection signals 6U to 6W, and shift to the rotor position detection operation mode. becomes.

FIG. 1 shows the rotational speed of the motor at the time of transition from the synchronous operation mode to the rotor position detection mode according to the present invention. As shown in FIG. 1, during synchronous operation, the vehicle is accelerated at a certain acceleration rate until time t1. Then, at time t1, the acceleration rate of the synchronous operation speed is lowered to perform gentle acceleration. As a result, the rotor position detection signal is stably established, and the state is sufficient for mode transition. When this state is reached, that is, at time t2, the brushless motor is operated while accurately detecting the magnetic pole position of the magnet rotor 5 by shifting from the synchronous operation mode to the rotor position detection operation mode.

[0016]

As described above, according to the present invention, the rotor position detection signal is is stabilized, allowing for smooth mode transitions in a short period of time.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing changes in operating speed at startup of a brushless motor in an embodiment of the present invention.

FIG. 2 is a configuration diagram of a brushless motor driving device in an embodiment of the present invention.

FIG. 3 is a timing chart of rotor position detection signals and commutation signals according to the present invention.

FIG. 4 is a diagram showing changes in operating speed at startup of a brushless motor in a conventional example.

[Explanation of symbols]

3 Brushless motor 4 Armature winding 5 Magnet rotor 6 Rotor position detection means 6U to 6W Rotor position detection signal 7 Commutation signal generation means (microcomputer) 7U
~7Z Commutation signal U~W Voltage signal

Claims (1)

[Claims] 1. A voltage signal induced in the armature winding of a brushless motor having a magnetic rotor is detected, this voltage signal is converted into a rotor position detection signal by a rotor position detection means, and the rotor position is detected by detecting the voltage signal induced in the armature winding of a brushless motor having a magnetic rotor. A rotor position detection operation mode in which the brushless motor is operated by a commutation signal generated from a detection signal, and a rotating magnetic field is generated by a commutation signal generated from an external signal until the rotor position detection signal is established. and a synchronous operation mode in which the brushless motor is forcibly operated and accelerated, and the acceleration rate of the synchronous operation speed is reduced during a certain period immediately before transitioning from the synchronous operation mode to the rotor position detection operation mode. A method for starting a brushless motor characterized by: