JP2008220035A - Brushless motor starter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor starter that further quickly sets a rotor speed to a target frequency. <P>SOLUTION: The brushless motor starter is connected to a coil of a brushless motor so as to supply a starting current to the coil when starting from a state that a rotor of the brushless motor is stopped. An output voltage to the coil periodically changes on the basis of a prescribed drive waveform. A starting frequency of the drive waveform changes on the basis of a speed command signal. The amplitude of the drive waveform changes on the basis of an amplitude command signal. During the start of the brushless motor, the speed command signal has a waveform corresponding to a prescribed speed profile while the amplitude command signal has a waveform corresponding to a prescribed amplitude profile. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brushless motor starting device that does not use a sensor for detecting a rotor position, and more particularly to a brushless motor starting device that can set a rotor speed to a target frequency more quickly.

In general, brushless DC motors such as home appliances and OA devices are used in a wide range of fields, but in order to know the commutation timing of the current flowing to each phase of the armature, a means for detecting the position of the rotor is necessary. Detection means using a sensor such as a Hall element is common.
There is also known a method for detecting a rotor position from a counter electromotive voltage generated in a coil without using a sensor for the purpose of downsizing and cost reduction. That is, in driving a brushless motor that does not use a sensor for detecting the rotor position, the rotor position is detected using the back electromotive force generated in the non-energized phase coil of the motor in which the rotor is in a rotating state. There is known a sensorless driving method for determining a phase switching timing of energization to each coil. Here, since the back electromotive force does not occur until the rotor stops or reaches a certain rotation, several start-up techniques up to a speed at which position detection is possible are known.
Among them, as with stepping motor stepping, the phase to be energized with a predetermined frequency and voltage amplitude is switched, the back electromotive force is accelerated to a detectable speed, and the rotor poles are independent of the rotor position. A method for forcibly energizing and commutating the number of cycles equal to or greater than the number of pairs to synchronize the rotor with the drive waveform (Patent Document 1) or exciting a predetermined coil to move the rotor to a roughly predetermined position Then, a method is known in which the energized phases are sequentially switched from a state in which the rotor and the drive waveform are substantially synchronized to accelerate to a speed at which a counter electromotive voltage can be detected (Patent Document 2).
JP 2002-78376 A Japanese Patent Laid-Open No. 9-233985

However, the conventional brushless motor starting device has the following problems.
That is, back electromotive force cannot be detected when the rotor is stopped or rotating at low speed, and for starting from a stopped state to a rotational speed at which back electromotive force can be detected, a method of synchronous driving with a predetermined starting frequency in an open loop is used. Conventionally, the frequency of the drive waveform was raised stepwise to the starting frequency at the time of startup, and then made constant.In this startup method, the rotor is rapidly accelerated, so the amplitude of the voltage between the coil terminals is increased. There is a problem that it is necessary to increase the speed, and even after the rotor speed reaches the starting frequency, there is a problem that it becomes oscillating around the frequency and settling with respect to the starting frequency becomes slow.
In addition, since a back electromotive force does not occur until the rotor starts rotating, there is a problem that a large current flows.
In addition, when the starting torque of the load is large, there is a problem in that starting is delayed because a time lag occurs from the start of starting until the rotor starts moving.

In addition, a rectangular wave is used for detecting the back electromotive voltage, and there is a problem that the driving sound is large and the efficiency is low.
In addition, when the starting frequency is input stepwise, a large voltage between the coil terminals is required for accelerating the rotor. After reaching the starting frequency, especially when the inertia is large and the viscous torque is small, the starting is started. There was a problem that the settling was slowed by swinging around the frequency.
In addition, when the starting torque of the load is large, there is a problem in that starting is delayed because there is a time lag from the start of starting until the rotor starts moving.
In addition, for detection of the back electromotive voltage, a rectangular wave having a section in which the voltage applied to the coil is 0 is used as the driving waveform, which causes a problem that the driving sound is large and the efficiency is low.
The present invention has been made to solve the above-described conventional problems, and its object is to determine the rotor speed at the start of the rotor by appropriately setting the speed profile of the start frequency so that the rotor speed is determined by the start frequency. It is an object of the present invention to provide a brushless motor starting device that can be set faster than a target frequency.

In order to achieve the above-mentioned object, the invention according to claim 1 is a brushless motor starting device that is connected to a coil of a brushless motor and supplies a starting current to the coil when the brushless motor starts. The output voltage to is periodically changed based on a predetermined drive waveform, the starting frequency of the drive waveform is changed based on a speed command signal, and the amplitude of the drive waveform is changed based on an amplitude command signal. When the brushless motor is started, the speed command signal and the amplitude command signal are waveforms according to a predetermined speed profile and amplitude profile, respectively.
The invention according to claim 2 is a brushless motor starting device connected to a coil of a brushless motor and supplying a starting current to the coil when the brushless motor is started, and includes a speed profile, an amplitude profile, and a reference driving waveform. Rewritable storage means for holding the data, start command signal generation means for generating a speed command signal and an amplitude command signal in accordance with speed profile data and amplitude profile data recorded in the rewritable storage means, and the rewrite Three-phase drive waveform generating means for reading reference drive waveform data stored in a possible storage means and outputting three reference drive waveforms having different phases as a first drive signal at a start frequency according to the speed command signal And multiplying the amplitude command signal and the first drive signal, Multiplication means for outputting a second drive signal with an amplitude in accordance with a width command signal, and output means connected to the motor coil of the brushless motor and supplying a terminal voltage based on the second drive signal to the brushless motor The activation frequency changes based on a speed command signal, and the amplitude changes based on an amplitude command signal.

According to a third aspect of the present invention, the speed profile data and the amplitude profile data are set so that the startup frequency is raised at a constant acceleration and the amplitude decreases when the amplitude approaches a target speed.
The invention according to claim 4 is characterized in that, in the amplitude profile, an output value for a predetermined time after starting is limited to be smaller than a final value of the amplitude profile.
According to a fifth aspect of the present invention, in the acceleration from the start of activation of the brushless motor to a speed at which the rotor can be detected at a predetermined speed or a position where the position of the rotor can be detected, the speed profile has a predetermined first speed. It has a first speed profile until it reaches one speed, and then has a second speed profile up to a predetermined second speed.
The invention according to claim 6 is characterized in that the velocity profile is expressed by a quadratic function with respect to time.
The invention according to claim 7 is characterized in that the velocity profile is expressed by a sine function with respect to time.
The invention according to claim 8 is characterized in that an initial phase of the drive waveform is a phase advanced from a synchronous phase with the rotor.
The invention according to claim 9 is characterized in that the drive waveform has a first waveform and a second waveform, and is switched from the first waveform to the second waveform after the speed profile ends.

According to the present invention, by appropriately setting the speed profile of the starting frequency, the rotor speed can be set faster than the target frequency determined by the starting frequency when the rotor is started.
In addition, according to the present invention, since the rotor does not move immediately after start-up, it is possible to prevent an overcurrent from flowing through the coil due to the fact that no counter electromotive voltage is generated in the coil.
Further, according to the present invention, it is possible to accelerate to a faster frequency with the same drive waveform amplitude as compared with the conventional case where the starting frequency rises stepwise.
In addition, according to the present invention, the speed profile smoothly converges to the final value, so that the rotor can be set to the target frequency more quickly.
In addition, according to the present invention, it is possible to compensate for the time lag from the start of start to the start of the rotor due to the start torque and friction, and to start the rotation of the rotor earlier, thereby shortening the start time. be able to.
In addition, according to the present invention, by setting a sine wave in the first waveform, noise can be reduced and efficient start-up can be performed, and a waveform having a section in which the output is 0 in the second waveform. By setting, it is possible to detect a counter electromotive voltage generated in the coil and shift to sensorless driving.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a configuration diagram of an embodiment of a brushless motor activation device according to the present invention.
As shown in FIG. 1, the brushless motor starting device is for starting the three-phase brushless motor 1, and the starting command signal generating unit 2 is connected to the three-phase driving waveform forming unit 4 and the multiplication via the switching unit 8. The rewritable memory 3 connected to the circuit 5 is connected to the start command signal generating unit 2 and the three-phase drive waveform forming unit 4, and the multiplier circuit 5 is connected to the three-phase drive waveform forming unit 4 and outputting The back electromotive force detection circuit 7 is connected to the three phase brushless motor 1 and connected to the closed loop circuit 9 via the unit 6, and is connected to the closed loop circuit 9 and the back electromotive force detection circuit. 7 is connected to the switching unit 8.
The rewritable memory 3 holds the data of the speed profile, the amplitude profile, and the reference drive waveform, and the start command signal generator 2 follows the speed profile data and the amplitude profile data recorded in the rewritable memory 3. A speed command signal and an amplitude command signal are generated.
The three-phase drive waveform generator 4 reads the reference drive waveform data stored in the rewritable memory 3, and outputs three reference drive waveforms whose phases are different by 120 degrees from each other at a frequency according to the speed command signal a. Output as drive signal (before amplitude multiplication) c. Here, FIGS. 2A and 2B show the speed command signal a when the reference drive waveform read from the rewritable memory 3 is a sine wave as shown in FIG. A drive signal (before amplitude multiplication) c is shown. FIGS. 2A and 2B show the speed command signal a and the drive signal (when the reference drive waveform read from the rewritable memory 3 is a sine wave as shown in FIG. FIG. 3 is a waveform diagram showing a reference drive waveform of a sine wave.

The multiplication circuit 5 multiplies the amplitude command signal b and the drive signal (before amplitude multiplication) c and outputs a drive signal d. 4A and 4B show the amplitude command signal b and the drive signal d (only one phase is shown).
The output unit 6 is connected to the motor coil of the three-phase brushless motor 1 so that the terminal voltage based on the drive signal d becomes U, V, W, such as multiplying the drive signal d by a predetermined gain or PWM modulation. The current is output and supplied to each coil of the brushless motor 1.
The counter electromotive force detection circuit 7 is a circuit for detecting a counter electromotive voltage generated in the non-energized phase coil, and outputs a signal indicating the position or speed of the rotor to the closed loop circuit 9 and also to the switching means 8. A command switching signal g indicating whether or not the back electromotive voltage is detected is output.
The switching means 8 refers to the command switching signal g and switches the generation source of the speed command signal a and the amplitude command signal b, that is, switches between open loop driving and closed loop driving.
The closed loop circuit 9 also follows a speed command signal a and an amplitude command signal b calculated from the rotor position or speed information of the three-phase brushless motor 1 by the back electromotive voltage detection circuit 7 so as to follow the target speed input signal f. Is output.

Next, the operation of the brushless motor starting device configured as described above will be described with reference to the flowchart of FIG.
First, in step S101, a predetermined voltage is applied to the coils of the three-phase brushless motor 1, thereby positioning the rotor to approximately a predetermined position. In step S102, voltage output to the terminal is started according to the speed profile and amplitude profile stored in the rewritable memory 3. In step S103 and step S104, the reference drive waveform is switched to a waveform having a section with an amplitude of 0 shown in FIG. As a result, detection of the counter electromotive voltage becomes possible, and in step S105, the counter electromotive force detection circuit 7 starts detecting the counter electromotive voltage generated in the coil. When the counter electromotive voltage is detected, the command switching is performed. The switching unit 8 that monitors the signal g shifts the drive of the brushless motor 1 from the open loop drive to the closed loop drive. If no back electromotive voltage is detected, the process returns to the first step S101 and the start sequence is repeated.
With the configuration and operation described above, the sensorless activation of the brushless motor 1 is performed according to the desired speed profile and amplitude profile by rewriting the speed profile data and amplitude profile data held in the rewritable memory 3. .
Note that other reference drive waveforms read from the rewritable memory 3 include the waveforms shown in FIG. The reference driving waveform may be switched from the first waveform shown in FIG. 3 to the second waveform shown in FIG. 8 after the speed profile is completed.

Here, FIGS. 5 (a), 5 (b), 6 (a), (b) and 7 (a), (b) show the simulation results of the startup of the brushless motor with different profiles, respectively. 5 (a) (b), FIG. 6 (a) (b) and FIG. 7 (a) (b), the upper plot of each figure takes time on the horizontal axis and frequency on the vertical axis. (Dotted line) and the time change (thick line) of the rotation frequency of the rotor are shown, and the lower plot of each figure shows the time change of the amplitude command value (dotted line). However, the speed command value is a value converted to the rotor speed, and the amplitude command value is a value converted to the coil terminal output. Actually, the speed command value is a value obtained by multiplying the number of pole pairs, and the amplitude command value is a value obtained by dividing the gain in the output unit. The same applies hereinafter unless otherwise specified.
In the following, parameters and conditions used for simulation are as follows unless otherwise noted in each embodiment.
[1] Motor parameter inertia (including load): 5.17 × 10 ^ (− 5) [kg. m ^ 2], winding resistance: 1.2 [Ω]
Winding inductance: 1.6 × 10 (−3) [H], Number of poles: 10, Linkage magnetic flux: 0.05 [Wb]
Maximum static friction torque: 4.5 × 10 ^ (− 3) [N · m]
Viscous load coefficient: 4 × 10 ^ (− 3) [N · m · s]
[2] Startup condition reference drive waveform: sine wave speed: acceleration from 0 [Hz] to 1 [Hz], time to reach target frequency: 0.1 [s]
Voltage amplitude of drive waveform at coil terminal: 1.25 [V], load torque: 3 × 10 ^ (− 3) [N · m]

First, when start-up is started at time 0.1 [s], FIGS. 5A and 5B show the rotor in the case where the start-up frequency is raised stepwise and the amplitude of the drive waveform is constant as in the prior art. It is a simulation result of the time change of speed. 6A and 6B show simulation results of changes in the rotor speed when the starting frequency is raised at a constant acceleration and the amplitude of the drive waveform is constant. FIGS. 7A and 7B are simulation results of changes in the rotor speed when the starting frequency is raised at a constant acceleration and the amplitude of the drive waveform decreases as it approaches the target speed.
Based on the simulation results, as shown in FIGS. 7A and 7B, the speed profile data and the amplitude profile data are set so that the startup frequency is raised at a constant acceleration, and the amplitude of the drive waveform decreases as it approaches the target speed. By doing so, it is understood that the speed of the rotor can be set to the target frequency more quickly when the brushless motor is sensorlessly activated.
According to this embodiment, the speed profile of the startup frequency and the amplitude profile of the drive waveform are changed so that the frequency of the drive waveform changes based on the speed command signal and the amplitude of the drive waveform changes based on the amplitude command signal. By setting, the rotor speed can be settled faster to the target frequency determined by the starting frequency when the rotor is started.

Next, another embodiment (Embodiment 2) of the brushless motor starter according to the present invention will be described. Hereinafter, in all the embodiments, the description of the same parts as those in the first embodiment will be omitted.
In the second embodiment, the speed profile data recorded in the rewritable memory 3 is a profile (not shown) that is input stepwise at a start frequency of 1 [Hz] at time 0 [s]. As shown in FIG. 9 (a), when the value of the amplitude profile is fixed, and as shown in FIG. 9 (b), the start-up is started at time 0 [s], and until time 0.05 [s] When the amplitude profile data is set so that the voltage amplitude at the terminal is equivalent to 0.75 [V] and thereafter equivalent to 1.25 [V], FIG. A comparison of simulation results of flowing current values (only one phase is shown) is shown.
At the time of starting the brushless motor, there is a problem that a large current flows through the coil because no back electromotive force is generated until the rotor starts moving after the voltage application to the starting coil is started. As in 2, the amplitude command value is limited to be smaller than the final value of the amplitude profile for a predetermined time after the start of activation, thereby limiting the amplitude of the voltage applied to the coil terminal and preventing overcurrent.

Next, another embodiment (Embodiment 3) of the brushless motor starter according to the present invention will be described. Hereinafter, in all the embodiments, the description of the same parts as those in the first embodiment will be omitted.
In the third embodiment, the speed profile data recorded in the rewritable memory 3 follows the first speed profile up to the first speed and the second speed up to the second speed as shown in FIG. According to the profile, a section in which the speed is constant is set between the end of the first speed profile and the start of the second speed profile. FIG. 11 is an explanatory graph of a speed profile in the third embodiment.
The speed profile shown in FIG. 11 is as follows.
4 * sin {π / 0.3 * (t−0.1)} (0.1 ≦ t ≦ 0.25)
4 (0.25 <t <0.3)
50 * (t−0.3) ^ 2 + 4 (0.3 ≦ t <0.4)
−50 * (t−0.5) ^ 2 + 5 (0.4 ≦ t ≦ 0.5)

12 (a), 12 (b) and 12 (c) show the velocity profile obtained by converting the value of the amplitude profile recorded in the rewritable memory 3 into a voltage amplitude at the coil terminal and fixing it to 2.3 [V]. Is the step speed, the acceleration is constant, and the profile shown in FIG. 4, the rotor speed when the drive signal is accelerated from 0 [Hz] to 5 [Hz] at 0.4 [s] It is the simulation result of time change of. It can be seen that the amplitudes of the voltages applied to the coils are the same, but the two examples except the speed profile shown in FIG. 4 step out and fail to accelerate.
Since the back electromotive force is generated in proportion to the rotation speed of the rotor, the amplitude of the current flowing in the coil of the motor is reduced. Therefore, if the voltage amplitude applied to the coil terminals is the same, the speed of the rotor increases. Torque decreases. In other words, the limit acceleration that can be accelerated without step-out decreases, and the rotor must accelerate more slowly as the speed increases.
Therefore, when the rotor speed is low and acceleration that can be accelerated without step-out is large, the rotor is accelerated according to the first speed profile that accelerates rapidly, the rotor speed becomes high, and step-out occurs. If the acceleration that can be accelerated without the acceleration is small, the rotor is accelerated according to the second speed profile that accelerates slowly.

At startup, the rotor speed oscillates around the startup frequency. However, in a region where the speed increases and the margin decreases with respect to the acceleration at which step-out does not occur, the rotor greatly fluctuates with respect to the startup frequency. If you move, you are more likely to exceed the limit of step-out. Therefore, by providing a constant speed section between the first speed profile and the second speed profile, the rotation frequency of the rotor is set to suppress vibrations, and step-out hardly occurs in subsequent acceleration.
According to the third embodiment, as the speed of the rotor increases, the rotor accelerates more gently and with less fluctuation in the rotor acceleration. Therefore, if the voltage amplitude applied to the coil terminals is the same, the speed is further increased. It can be accelerated.
Activation conditions in the third embodiment:
Speed: Acceleration from 0 [Hz] to 5 [Hz], time to reach target frequency: 0.4 [s]
Voltage amplitude of drive waveform at coil terminal: 2.3 [V]

Next, another embodiment (Embodiment 4) of the brushless motor starter according to the present invention will be described. Hereinafter, in all the embodiments, the description of the same parts as those in the first embodiment will be omitted.
FIGS. 13A and 13B show the speed command signal and the rotor speed when the acceleration is constant (upper plot) and when the speed profile is expressed by a quadratic function with respect to time (lower plot). The speed profile data recorded in the rewritable memory 3 is expressed as follows in the function for the time t:
32 * (t−0.1) ^ 2 (0.1 ≦ t <0.225)
−32 * (t−0.35) ^ 2 + 1 (0.225 <t ≦ 0.35)
It can be seen that acceleration according to the speed profile of the fourth embodiment settles to the target speed earlier.
Here, at the point of the speed increase of the speed command signal, that is, at the point where the acceleration changes rapidly, the rotor tends to vibrate away from the synchronous phase with the drive waveform, but to the final speed value according to the fourth embodiment. By having a speed profile that settles smoothly, the rotor can be quickly settled to the target starting frequency.
Activation conditions in the fourth embodiment:
Time to reach the target frequency: 0.25 [s]

Next, another embodiment (Embodiment 5) of the brushless motor starter according to the present invention will be described. Hereinafter, in all the embodiments, the description of the same parts as those in the first embodiment will be omitted.
FIGS. 14A and 14B show the speed command signal and rotor speed time when the acceleration is constant (upper plot) and when the speed profile is expressed as a sine function with respect to time (lower plot). The simulation result of the change is shown, and the speed profile data recorded in the rewritable memory 3 is expressed as follows in the function for the time t,
[Sin {5π * (t−0.1) −π / 2} +1] / 2 (0.1 ≦ t ≦ 0.3)
It can be seen that acceleration according to the speed profile of the fifth embodiment settles to the target speed earlier.
Here, at the point of the speed increase of the speed command signal, that is, at the point where the acceleration changes suddenly, the rotor tends to vibrate away from the synchronous phase with the drive waveform. By having a speed profile that settles smoothly, the rotor can be settled quickly to the target starting frequency.
Activation conditions in the fifth embodiment:
Time to reach the target frequency: 0.2 [s]

Next, another embodiment (Embodiment 6) of the brushless motor starter according to the present invention will be described. Hereinafter, in all the embodiments, the description of the same parts as those in the first embodiment will be omitted.
In the sensorless activation method according to the sixth embodiment, first, a predetermined voltage is applied to the coil terminal of the brushless motor 1 to perform positioning to move the rotor to a roughly balanced position. The starting operation is started with a phase that is synchronized with the position of the rotor and advanced by a predetermined amount from the phase of the drive signal as an initial phase of the drive signal.
15A and 15B show a case where the initial phase of the reference drive waveform stored in the rewritable memory 3 is not advanced (upper plot) and a case where the phase of the reference drive waveform is advanced ( The simulation result of the time change of the rotor speed is shown for the activation of the lower plot). However, the speed profile data recorded in the rewritable memory 3 is as follows in the function for the time t.
sin (5πt) (0 ≦ t ≦ 0.1)
It can be seen from the advance angle of the initial phase in the sixth embodiment that the rotor starts rotating immediately after the start-up.
Here, if the drive waveform does not advance until the torque generated in the rotor becomes larger than the load and the shaft static friction, the rotor does not start to move. In other words, the motor can be started earlier than before by setting the initial phase of the drive waveform at the start of startup to a phase that is appropriately advanced from the synchronous phase with respect to the rotor position. Represents the phase of the drive waveform with respect to the rotor position when the electromagnetic forces are balanced and the rotor is stationary).

It is a block diagram of one Embodiment of the starting device of the brushless motor by this invention. (A) and (b) are waveform diagrams showing a speed command signal a and a drive signal (before amplitude multiplication) c when the reference drive waveform read from the rewritable memory 3 is a sine wave as shown in FIG. is there. It is a wave form diagram which shows the standard drive waveform of the sine wave read from the rewritable memory. (A) and (b) are waveform diagrams showing an amplitude command signal b to the multiplication circuit 5 and a drive signal d (only one phase is shown) from the multiplication circuit 5. (A) and (b) are waveform diagrams of simulation results of changes in rotor speed over time when the starting frequency is raised stepwise and the amplitude of the drive waveform is constant as in the prior art. (A) and (b) are waveform diagrams of simulation results of changes in rotor speed when the starting frequency is raised at a constant acceleration and the amplitude of the drive waveform is constant. (A) and (b) are waveform diagrams of simulation results of changes in rotor speed when the startup frequency is raised at a constant acceleration and the amplitude of the drive waveform decreases as it approaches the target speed. It is a wave form diagram which shows the standard drive waveform of the rectangular wave read from the rewritable memory. (A) and (b) are waveform diagrams showing amplitude command signals when the amplitude profile is constant in the second embodiment and when the amplitude is limited for a predetermined time from the start of activation. (A) (b) is a wave form diagram which shows the electric current value (only one phase is shown in figure) in each case of Fig.8 (a) (b). It is a wave form diagram which shows the speed command signal in Embodiment 3. (A), (b), and (c) fix the amplitude profile value recorded in the rewritable memory 3 to a predetermined value, and the profile shown in FIG. 2 when the velocity profile is stepped or the acceleration is constant. FIG. 6 is a waveform diagram of a simulation result of a temporal change in rotor speed when the drive signal accelerates in the case of FIG. (A) and (b) are waveform diagrams of simulation results of a time change of the speed command signal and the rotor speed when the acceleration is constant and the speed profile is expressed by a quadratic function with respect to time. (A) (b) is a wave form diagram of a simulation result of a time change of a speed command signal and a rotor speed when acceleration is constant and a speed profile is expressed by a sine function with respect to time. (A) and (b) show the rotor speed time for starting when the initial phase of the reference drive waveform stored in the rewritable memory 3 is not advanced and when the phase of the reference drive waveform is advanced. It is a wave form diagram of a simulation result of change. It is an operation | movement flowchart of the starting device of the brushless motor shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Brushless motor, 2 ... Start command signal generation part, 3 ... Memory, 4 ... Three-phase drive waveform formation part, 5 ... Multiplication circuit, 6 ... Output part, 7 ... Back electromotive voltage detection circuit, 8 ... Switching part, 9 ... closed loop circuit, a ... speed command signal, b ... amplitude command signal, c ... drive signal (before amplitude multiplication), d ... drive signal, e ... profile end signal, f ... target speed input signal, g ... command switching signal

Claims (9)

A brushless motor starting device connected to a coil of a brushless motor and supplying a starting current to the coil when the brushless motor is started,
The output voltage to the coil is periodically changed based on a predetermined drive waveform, the starting frequency of the drive waveform is changed based on a speed command signal, and the amplitude of the drive waveform is based on an amplitude command signal. The brushless motor starting device is characterized in that, when the brushless motor is started, the speed command signal and the amplitude command signal have waveforms according to a predetermined speed profile and amplitude profile, respectively. A brushless motor starting device connected to a coil of a brushless motor and supplying a starting current to the coil when the brushless motor is started,
Rewritable storage means for holding data of velocity profile, amplitude profile and reference drive waveform;
A start command signal generating means for generating a speed command signal and an amplitude command signal according to the speed profile data and the amplitude profile data recorded in the rewritable storage means;
A three-phase drive waveform that reads reference drive waveform data stored in the rewritable storage means and outputs three reference drive waveforms having different phases as a first drive signal at a start-up frequency according to the speed command signal Generating means;
Multiplication means for multiplying the amplitude command signal and the first drive signal and outputting a second drive signal with an amplitude according to the amplitude command signal;
Output means connected to a motor coil of the brushless motor and supplying a terminal voltage based on the second drive signal to the brushless motor;
The brushless motor starting device, wherein the starting frequency changes based on a speed command signal, and the amplitude changes based on an amplitude command signal.   3. The brushless motor start according to claim 1, wherein the start-up frequency is started at a constant acceleration, and the speed profile data and the amplitude profile data are set so that the amplitude decreases when the amplitude approaches a target speed. apparatus.   3. The brushless motor starting device according to claim 1, wherein in the amplitude profile, an output value for a predetermined time after starting is limited to be smaller than a final value of the amplitude profile.   In acceleration from the start of activation of the brushless motor to a speed at which the rotor can be detected at a predetermined speed or a position at which the rotor can be detected, the speed profile is a first speed until the predetermined first speed is reached. 3. The brushless motor starting device according to claim 1, wherein the brushless motor starting device has a profile and subsequently has a second speed profile up to a predetermined second speed.   The brushless motor starting device according to claim 1, wherein the speed profile is expressed by a quadratic function with respect to time.   The brushless motor starting device according to claim 1, wherein the speed profile is expressed by a sine function with respect to time.   The brushless motor starting device according to claim 1 or 2, wherein an initial phase of the driving waveform is a phase advanced from a synchronous phase with the rotor.   3. The brushless motor starting device according to claim 1, wherein the driving waveform has a first waveform and a second waveform, and the first waveform is switched to the second waveform after the speed profile is finished. 4. .

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