JPH03235695A - Method and apparatus for starting brushless motor - Google Patents

Abstract

PURPOSE:To smoothly start by suitably increasing the frequency of a revolving magnetic field generated in an armature winding and a duty ratio as time goes. CONSTITUTION:After a start command means 12 generates a command, the frequency and a duty ratio of the output signal of a synchronizing signal generation means 10 are simultaneously increased along a rectilinear line of a predetermined slope as time goes to rotatably start a magnet rotor 5 before the start of the motor 3 is established. After the start is established, a change-over means 7 is converted to drive the motor 3 based on the output signal of a position detection means 6.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a brushless motor, and in particular detects the relative position between a magnet rotor and an armature winding by an induced voltage induced in the armature winding. This relates to starting a brushless motor for stable rotation.

Conventional technology Normally, a brushless motor requires a detector to detect the magnetic pole position of its rotor. Therefore, the reliability of the detectors cannot be guaranteed, and these detectors cannot be used.
~ Therefore, in such applications, Table 1 shows that although a method is used that detects the voltage signal induced in the armature winding and generates the motor commutation signal based on it without using a magnetic pole position detector, the armature A voltage signal is induced in the windings only when the rotor is rotating; when the rotor is stopped, magnetic pole position information cannot be obtained - in other words, this voltage signal cannot be used at startup. .

Therefore, at startup, a specific signal is given that generates a rotating magnetic field in the armature winding regardless of the rotor's magnetic pole position.
This particular signal ignores the magnetic field position of the rotor, and as a result, a large starting current flows during startup. If the allowable current value of the semiconductor switching element group, which cuts off the current to the armature winding, is exceeded, startup is impossible. In order to solve this problem, a method has been devised in the past to reduce the voltage of the DC power supply that supplies current to the motor only at the time of starting, thereby reducing the starting current (for example, JP-A-61-1
35385).

Problems to be Solved by the Invention However, in the case of large brushless motors, such as those used to drive the compressor of air conditioners, the power supply capacity is several kVA.
Normally, in such applications, the power supply voltage is kept constant, and the voltage is controlled by controlling the duty ratio of the voltage signal pulse.
So-called Norse width modulation is used. This is to avoid increasing the size of the device and cost savings due to the configuration of a variable voltage power supply. Therefore, the starting method shown in the conventional example cannot be used in the application of large equipment as described above. In view of the above-mentioned conventional problems, a method for starting a brushless motor suppresses starting current and vibration at the time of starting the motor and enables smooth starting even when voltage is controlled by Noculus width modulation. Means for Solving the Problems In order to solve the above problems, the present invention provides: Before the start of the motor is determined, the frequency of the rotating magnetic field generated in the armature winding of the brushless generator is , the duty ratio as a means of controlling the motor applied voltage is simultaneously increased along a straight line with a constant slope over time, and after a certain period of time has passed, the voltage signal induced in the armature winding is converted based on the signal obtained. At least one of the frequency and duty ratio of the rotating magnetic field increases along a curve whose differential coefficient decreases over time, and the other increases along a curve with a constant slope over time. It has a configuration that increases along a straight line.

Furthermore, at least one of the frequency and duty ratio of the rotating magnetic field is increased along a plurality of straight lines whose slope decreases with time, and the other is set along a straight line whose differential coefficient decreases with time or along a straight line with a constant slope. It is equipped with a configuration to increase the amount of data.

A brushless motor having a three-phase armature winding connected to an ungrounded neutral point, a DC power supply, a group of semiconductor switching elements for cutting off current to the armature winding, and a magnet rotor. A motor, a start command means, a synchronization signal generation means for outputting a synchronization signal in response to a command from the start command means, and a rotating magnetic field is generated in the armature winding using the signal output from the synchronization signal generation means. A rotating magnetic field generating means,
position detection means for detecting the relative position of the armature winding and the magnet rotor based on a voltage signal induced in the armature winding; an output signal of the rotating magnetic field generation means; and an output signal of the position detection means. a switching means for selecting and outputting a switch; a switching command means for giving a switching command to the switching means; and a 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 the output signal of the drive signal generation means based on the command of the duty ratio command means. The frequency of the output signal of the synchronizing signal generating means and the duty ratio are simultaneously increased along a straight line with a constant slope over time, and the magnet rotor is started to rotate. After the start is confirmed, the switching means is switched to The motor is configured to drive the motor based on the output signal of the position detecting means, and at least one of the frequency of the output signal of the synchronizing signal generating means and the duty ratio follows a curve whose differential coefficient decreases with time. It is also possible to have a configuration in which one increases along a straight line with a constant slope over time, and the other increases along a straight line with a constant slope over time.
At least one of the frequency of the output signal of the synchronization signal generating means and the duty ratio is increased along a plurality of straight lines whose slope decreases with time, and the other is a curve whose differential coefficient decreases with time, or a straight line with a constant slope. It has a configuration that increases along the line.

Effect: With the above-described configuration, the present invention appropriately increases the frequency and duty ratio of the rotating magnetic field generated in the armature winding over time, thereby suppressing the starting current and vibration when starting the motor, and realizing smooth starting. That will happen.

EXAMPLE Hereinafter, the first example of the present invention will be explained with reference to the drawings. Figure 4 is a block diagram of a brushless motor starting device in the first example of the present invention. 2 is a semiconductor switching element group consisting of 6 transistors Q1 to Q6 and 6 diodes connected in antiparallel to each of them. 3 is a brushless motor with armature winding 4 and magnets connected in 3 phases. It consists of a rotor 5. 6 is a position detection means, 7 is a switch north, 8 is a drive signal generation means, 9 is a pulse width modulation means 10 is a synchronization signal generation hand i, 11 is a rotating magnetic field generation means 12 is a start command hand! ,
13 is a switching command means, and 14 is a duty ratio command means. With the above configuration, at the time of startup, the rotating magnetic field generating means 11
The output signal is transmitted to the drive signal generation means 8 by the switching means 7, and the output signal is subjected to pulse width modulation to drive the transistor of the semiconductor switching element group 2 and start the brushless motor 34.Then, the brushless motor 3 starts rotating. Then, the position detecting means 6 detects the magnetic pole position of the magnet rotor 5 from the induced voltage generated in the armature winding 4, and the signal is transmitted to the drive signal generating means 8 by the switching means 7, which applies pulse width modulation to the semiconductor. It drives the transistors of the switching element group 2 and controls the brushless motor 3. FIG. 5 (top) This is a more concrete configuration of the block diagram in FIG. 4, and the same parts or functions as those in FIG. 4 are given the same reference numerals. In the figure, 1 to 5 are exactly the same as in FIG. 4, and a6 is a position detection circuit consisting of 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; and 13 is a switching command circuit; 15 is a microcomputer; It corresponds to the means 14 and outputs a start command signal 151 to the synchronization signal generation circuit 10 and a duty ratio command signal 153 to the pulse width modulation circuit 9, respectively. The operation of the embodiment of the brushless motor starting device configured as described above will be explained. First, even if the microcomputer 15 outputs the starting command signal 151 and the switching signal 15 duty ratio command signal 153 simultaneously, signal 151
The synchronous signal generating circuit 10C receives the synchronous signal and outputs the synchronous signal 100 as shown in FIG.
The switching circuit 7 is a circuit that switches whether the input signals 87 to 89 of the drive signal generation circuit 8 are used as the output signals of the position detection circuit 6 or the output signals of the rotating magnetic field generation circuit 11. , even if the switching signal 152 switches to the output signal side of the rotating magnetic field generating circuit 11 at startup, the output signals 111 to 1 of the rotating magnetic field generating circuit 11
13 is taken into the drive signal generation circuit 8, and output signals 81 to 86 shown in FIG. 6 are outputted from the same circuit. These output proof boards 81 to 83 are further connected to a pulse width modulation circuit 9.
Pulse width modulation is performed based on the duty ratio command signal 153, and each becomes a drive signal for the transistors Q1 to Q3 of the semiconductor switching element group 2. -Output signals 84 to 86 of the blade drive signal generation circuit 8 (
These drive signals serve as drive signals for the transistors Q4 to Q6 of the semiconductor switching element group 2.A These drive signals switch the six transistors of the semiconductor switching element group 2, and as a result, a rotating magnetic field is generated in the armature winding 4, and the magnet The rotor 5 rotates and the brushless motor 3 starts. Here, the synchronization signal 100 is as shown in FIG. The output is increased along the line. Further, as shown in FIG. 1, the duty ratio command signal 153 is also output at the same time as the start command signal 151 rises so that the duty ratio increases along a straight line with a constant slope over time. When the frequency and duty ratio of the synchronizing signal 100 reach values that can maintain stable rotation of the brushless motor 3, they stop increasing and maintain their constant values. air
Based on the output signals 641 to 643 of the position detection circuit 6, it is determined that the brushless motor 3 has started, and the switching signal 152 is output, and the switching circuit 7 is switched to the position detection circuit 6 side. The input signals 87 to 89 of the signal generation circuit 8 are the output signals 641 to 64 of the position detection circuit 6.
3, and thereafter the induced voltage signal 4 generated in the armature winding 4
The brushless motor 3 is driven by the switching signal 152, and the starting command signal 151 is canceled and the series of starting operation procedures is reset to the initial state. Even after startup is confirmed, the microcomputer 15 outputs the applied voltage control command for speed control of the brushless motor 3. The above operation suppresses the starting current and vibration when starting the motor when voltage is controlled by pulse width modulation. Although smooth start-up is possible, the second embodiment of the present invention will now be described with reference to FIG. In the first embodiment, the synchronization signal 100 and the duty ratio command signal 153 are changed in a range as shown in FIG. However, the operations other than these are the same as in the first embodiment.
The above operation suppresses the starting current and vibration when starting the motor even when voltage is controlled by pulse width modulation, and enables smoother starting.
By increasing the frequency and duty ratio over time along the curve shown in Figure 2, the startup time can be shortened, and the duration of the large current and vibration associated with startup can be shortened. Next, a third embodiment of the present invention will be explained with reference to FIG. 3.The configuration of the device is the same as that of the first embodiment.
The synchronization signal 100 and the duty ratio command signal 153 are changed as shown in Fig. 3.The frequency and duty ratio of the synchronization signal 1000 decrease with time.
increase along two straight lines. The operations other than these are the same as those in the first embodiment. The above operations suppress the starting current and vibrations when starting the motor, making smoother starting even when voltage is controlled by pulse width modulation. By increasing the frequency and duty ratio of the Sarabanmi synchronization signal 100 over time along three straight lines as shown in Figure 3, the startup time can be shortened, and the duration of the large current and vibration associated with startup can be shortened. Furthermore, by linearizing the changes in the frequency and duty ratio of the synchronization signal 100, the generation of those change patterns can be performed by simple proportional equation calculations, and the generation of the synchronization signal 100 and duty ratio command signal 153 can be performed. In the first to third embodiments, the synchronizing signal generating circuit, the first rotating magnetic field generating circuit 11, and the command circuit 13 are each made into independent circuits. You can have the computer 15 do it.The effects of the invention are as follows.
a phase armature winding, a DC power supply, a group of semiconductor switching elements for supplying or interrupting current to the armature winding, a brushless motor having a magnet rotor, a start command means, and a command from the start command means. synchronous signal generating means for outputting a synchronous signal; rotating magnetic field generating means for generating a rotating magnetic field in the armature winding using the signal output from the synchronous signal generating means; and a voltage induced in the armature winding. a position detecting means for detecting the relative position of the forward bending voltage winding and the magnet rotor based on a signal; and a switching means for selecting and outputting an output signal of the rotating magnetic field generating means and an output signal of the position detecting means. , a switching command means for giving a switching command to the switching means, a drive signal generation means for generating a drive signal for the switching element group using an output signal of the switching means, a duty ratio command means, and the drive signal generation means. a pulse width modulation means for applying pulse width modulation to the output signal based on a command from the duty ratio command means;
By simultaneously increasing the frequency of the output signal of the synchronizing signal generating means and the duty ratio along a straight line with a constant slope over time, it is possible to reduce the starting current and vibration when starting the motor even when voltage control is performed by pulse width modulation. suppress
This enables smooth startup. (2) At least one of the frequency of the output signal of the synchronizing signal generating means and the duty ratio is increased along a curve whose differential coefficient decreases over time, and the other is increased along a straight line with a constant slope over time. By doing so, the startup time can be shortened, and the duration of the large current and vibration associated with startup can be shortened. A curve whose slope increases along several straight lines, one whose derivative decreases over time
Alternatively, by increasing it along a straight line with a constant slope, the startup time can be shortened, the large current associated with startup and the duration of startup can be shortened, and a startup pattern can be easily generated. Even if it can be done

[Brief explanation of drawings]

FIGS. 1 to 3 are waveform diagrams showing how the frequency and duty ratio of the synchronizing signal of the brushless motor starting device are increased over time in the first to third embodiments of the present invention.
Figure 5 is a block diagram of the brushless motor starting device in the same embodiment. Figure 5 is a block diagram of the brushless motor starter in the same embodiment. Figure 6 is a waveform diagram of each part in the configuration diagram in Figure 5. ...DC electric current 2...Semiconductor switching element pulse 3...Brushless motor 4...Armature 5iL5...Magnet rotor, 6...Position detection half-submerged 7... ...Switching arrangement 8...Drive signal generation half-immersion 9...Pulse width modulation method 10...Synchronization signal generation hand i 100...Synchronization signal '4 11...Rotating magnetic field generation Half-submerged 12... Startup command Tesaka 13...
Switching command half-recessed 14...Duty ratio command means, 15
...Microcomputer 151...Start command signal 152...Switching signal 153...To duty ratio command signal

Claims (5)

[Claims] (1) Detecting a voltage signal induced in the armature winding of a brushless motor having a magnetic rotor, and generating a commutation signal for the brushless motor using the signal obtained by converting this voltage signal, In a brushless motor that does not include a magnetic pole position detector, the frequency of the rotating magnetic field generated in the armature winding of the brushless motor and the duty ratio as a control means for the motor applied voltage are simultaneously kept constant over time before motor startup is confirmed. A method for starting a brushless motor, comprising increasing the slope along a straight line, and driving the brushless motor based on a signal obtained by converting the voltage signal after starting is determined. (2) A claim characterized in that at least one of the frequency and duty ratio of the rotating magnetic field is increased along a curve whose differential coefficient decreases over time, and the other is increased along a straight line with a constant slope over time. 1. A method for starting the brushless motor described in 1. (3) At least one of the frequency and duty ratio of the rotating magnetic field is increased along a plurality of straight lines whose slope decreases over time, and the other is set along a curve whose differential coefficient decreases over time, or along a straight line with a constant slope. 2. The method for starting a brushless motor according to claim 1, further comprising increasing the number of brushless motors. (4) A brushless motor having a three-phase armature winding connected to an ungrounded neutral point, a DC power supply, a group of semiconductor switching elements for supplying or interrupting current to the armature winding, and a magnet rotor. a start command means; a synchronization signal generation means for outputting a synchronization signal in response to a command from the start command means; and a rotation for generating a rotating magnetic field in the armature winding using the signal output from the synchronization signal generation means. a magnetic field generating means, a position detecting means for detecting the relative position of the armature winding and the magnet rotor based on a voltage signal induced in the armature winding, and an output signal of the rotating magnetic field generating means and the position. a switching means for selecting, switching and outputting an output signal of the detection means; a switching command means for giving a switching command to the switching means; and a drive for generating a drive signal for the switching element group using the output signal of the switching means. A signal generating means, a duty ratio commanding means, and a pulse width modulation means for applying pulse width modulation to the output signal of the drive signal generating means based on a command from the duty ratio commanding means, and generating a command for the start commanding means. Before the activation of the rear motor is confirmed, the frequency of the output signal of the synchronizing signal generating means and the duty ratio are simultaneously increased along a straight line with a constant slope over time,
A starting device for a brushless motor, characterized in that the magnetic rotor is started to rotate, and after the starting is confirmed, the switching means is switched to drive the motor based on the output signal of the position detecting means. (5) At least one of the frequency and duty ratio of the output signal of the synchronization signal generating means is increased along a curve whose differential coefficient decreases over time, and the other is increased along a straight line with a constant slope over time. The brushless motor starting device according to claim 4, characterized in that: (6) At least one of the frequency and duty ratio of the output signal of the synchronization signal generating means is increased along a plurality of straight lines whose slope decreases with time, and the other is a curve whose differential coefficient decreases with time, or is constant. 5. The brushless motor starting device according to claim 4, wherein the inclination of the brushless motor is increased along a straight line.