JPH10191679A - Device for driving brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for driving a brushless motor which can supply a voltage in an arbitrary waveform to the brushless motor by using a minimum position sensor and by using a smaller data capacity. SOLUTION: A fundamental data table which is composed of electrical-angle data, at an electrical angle portion of 30 deg., obtained by comparing three-phase sine waves with carrier waves by triangular waves at a 1/127 cycle of the since waves and which is composed of an electrification mode and a conversion table by which the electrification mode is converted into voltage signals Vu, Vv, Vw according to a region in which one electric cycle is divided into 12 equal parts are stored in a ROM 12. In an interrupt processing (Sh), a microcomputer 1 converts the electrical angle data into time data at an electrical angle portion of 60 deg. on the basis of the counted value Dc of a counter 23, and the electrification mode is converted into the voltage signals Vu to Vw by using the conversion table. Then, whenever the counted value of the counter 23 agrees with the data which is set in a comparator 24, the voltage signals Vu to Vw are output sequentially in an interrupt processing (Sc), and a brushless motor 8 is driven via a voltage control circuit 25 and a drive means 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for driving a brushless motor by supplying a voltage having an arbitrary waveform to a winding.

[0002]

2. Description of the Related Art In recent years, fan motors for air conditioners and motors for driving electric vehicles have been widely used for controlling variable speed control and saving power consumption. For the purpose of improvement, a brushless motor is employed, and this is driven by an inverter device as a driving device.

For example, in a three-phase brushless motor, three Hall ICs, each of which has a simple structure and is the cheapest as a position sensor, are usually arranged at every 120 electrical degrees. The inverter device obtains a signal corresponding to the rotational position of the rotor using these Hall ICs, and drives the winding of the brushless motor by applying a voltage to the winding of the brushless motor by a 120-degree conduction method.

However, when the brushless motor is driven by the 120-degree conduction method, there is a period in which no current flows in the winding of the brushless motor, and the magnetic flux generated by the permanent magnet of the rotor is not used to the maximum extent. In addition, there is a problem in that, at the time of voltage switching, that is, at the time of commutation, a torque fluctuation accompanying this occurs in the brushless motor.

In the fields of home electric appliances such as air conditioners and washing machines, electric vehicles, and the like, there is a demand for reduction in power consumption and vibration, and for example, sine waves, etc., which are effective in improving efficiency and reducing torque fluctuation. There is a demand for an inverter device (drive device) that can supply the voltage waveform of (1) to the motor.

FIG. 19 shows a conventional example of such an inverter device. In FIG. 19 showing the electrical configuration, both terminals of an AC power supply 1 are connected to an AC input terminal of a full-wave rectifier circuit 3 via a reactor 2 on one side. The smoothing capacitor 4 is connected between the DC output terminals of the full-wave rectifier circuit 3, and the above constitutes the DC power supply circuit 5. The DC output terminals of the DC power supply circuit 5 are positive,
It is connected to the negative DC buses 6a and 6b.

The inverter main circuit 7 includes a transistor T connected in a three-phase bridge between the positive and negative DC buses 6a and 6b.
1 to T6, and flywheel diodes D1 to D6 connected in parallel to the transistors T1 to T6, respectively. Output terminals 7u, 7v, 7w of the inverter main circuit 7 are connected to star-connected phase windings 8u, 8v, 8w of the three-phase brushless motor 8, respectively.

A rotary shaft (not shown) of a brushless motor (hereinafter simply referred to as a motor) 8 is provided with a high-resolution encoder 9, and has output terminals 7 u, 7 v, 7 w of an inverter main circuit 7 and a motor 8. Windings 8u, 8
Current detectors (for example, Hall element type current detectors) 10u, 10v, and 10w are provided between v and 8w, respectively. These current detectors 10u, 10v, 10w are:
The currents flowing through the windings 8u, 8v, 8w are detected, respectively, and the signals Iu, Iv, Iw are output.

The output terminal of the encoder 9 is connected to the input terminal of the rotor phase counter 11,
Supplies the pulse signal Ea and the zero point signal Ez to the rotor phase counter 11, respectively.

A data bus as an output terminal of the rotor phase counter 11 is connected to address buses of the ROMs 12u, 12v and 12w.
The output data Pe is stored in the ROMs 12u, 12v and 12w.
As an address signal.
Data buses as output terminals of the ROMs 12u, 12v, and 12w are connected to input terminals of the D / A converters 13u, 13v, and 13w, respectively.
The output terminals of v and 13w are connected to one input terminals of multipliers 14u, 14v and 14w, respectively. The D / A converters 13u, 13v, and 13w include a ROM
The data given from 12u, 12v and 12w are converted to D /
A conversion is applied to multipliers 14u, 14v and 14w.

The other input terminals of the multipliers 14u, 14v and 14w are externally supplied with a current command signal Ia.
The output terminals of the 4w are comparison amplifiers 15u, 15v and 15w.
w is connected to one input terminal. The multipliers 14u, 14v, and 14w are connected to the D / A converter 13
The current command signals ieu, iev, and iew, which are the results of multiplying the output signals given from u, 13v, and 13w and the current command signal Ia, are supplied to the comparison amplifiers 15u, 15v, and 15w.

The other input terminals of the comparison amplifiers 15u, 15v and 15w are connected to current detectors 10u, 10v and 10w, respectively.
Are connected to the output terminals of the comparators 15u and 15u.
Output terminals of v and 15w are connected to one input terminal of comparators 16u, 16v and 16w. The comparison amplifiers 15u, 15v and 15w output signals Iu, Iv and Iw
And signals ieu, iev and iew are compared and amplified, and output signals veu, vev and vew are supplied to comparators 16u, 16v and 16w, respectively.

The other input terminals of the comparators 16u, 16v and 16w are connected to the output terminal of the triangular wave generator 17, and the output terminals of the comparators 16u, 16v and 16w are connected to a gate drive circuit comprising, for example, a photocoupler. 18 or 18
up, 18vp, 18wp
Gate drive circuits 18up to 18wp and 18un to 18wn
Are connected to the bases and emitters of the transistors T1 to T3 and the transistors T4 to T6, respectively.

In the comparators 16u, 16v and 16w, the carrier P of the PWM signal output from the triangular wave generator 17 is used.
By comparing z with the signals veu, vev, and vew, drive signals Dup, Dun, Dvp, Dvn, Dwp, Dwn are formed, and the transistors T1 to T6 of the inverter main circuit 7 are turned on / off by these drive signals. . Note that the DC power supply circuit 5, the DC buses 6a and 6b, the inverter main circuit 7, and the gate drive circuit 18 include a drive circuit 1 serving as drive means.
9.

As shown in FIG. 20, when the motor 8 rotates, the encoder 9 outputs a pulse signal Ea every several degrees of rotation angle (see (b)), and the rotor phase counter 11 counts the pulse signal. At the same time, by being reset by the zero point output Ez, the phase Pe of the rotor is cyclically shown in the range of 0 to 360 degrees (see (c)). R
From the OMs 12u to 12w, the rotor phase counter 11
A current pattern of current command data corresponding to the phase of the rotor indicated by is output. The current command data is D / A converted by D / A converters 13u to 13w, and
u to 14w, and the current command signals ieu, iev, i
ew is output (see (e)).

The comparison amplifiers 15u to 15w are provided with current command signals ieu, iev, iew and current detectors 10u, 10u.
v, 10w and output signals Iu, Iv, Iw,
The voltage command signals veu, v are supplied to the comparators 16u, 16v, 16w.
ev and ve are output (see (f)). And the comparator 1
6u, 16v, 16w are voltage command signals veu, vev, v
The drive signal is output to the gate drive circuit 18 by comparing the levels of ew and the carrier wave Pz. In this way, the current patterns stored in the ROMs 12u, 12v, and 12w are read in advance, and the current supplied to the motor 8 in units of several electrical degrees is feedback-controlled.

In this case, the ROMs 12u, 12v and 12v
The relationship between the data stored in w and the encoder 9 will be described with reference to FIG. When the number of poles of the motor 8 is four, the electrical angle per rotation is 720 degrees, and the pulse number Np required for the encoder 9 to obtain the resolution of 0.25 electrical angle is Np = 720/0. .25 = 2880
Becomes

The number Nd of data stored in the ROMs 12u to 12w is 360 / 0.25 = 1440,
If the resolution is 8 bits, the required storage capacity is 8 × 1
440 = 111520 (bits), and even when only the electrical angle of 30 degrees is stored, 8 × 30 / 0.25 = 96
0 bits are required.

[0019]

However, a high-resolution encoder 9 used in the above-described driving device is required.
And current detectors 10u, 10v, 1 for detecting current waveforms
Since 0w is expensive, the cost of the product increases significantly. In addition, the mounting of the encoder 9 is limited by the product dimensions, and it has not been possible to introduce the inverter device configured as described above in a product field that requires low cost and downsizing such as home electric appliances.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to minimize the use of expensive encoders and current detectors, minimize the number of position sensors, and reduce the amount of data required. An object of the present invention is to provide a brushless motor driving device capable of supplying a waveform voltage to the brushless motor.

[0021]

According to a first aspect of the present invention, there is provided a brushless motor driving apparatus comprising: a position sensor signal having a fixed phase relationship with an induced voltage generated in a plurality of windings of the brushless motor; A plurality of position sensors, a time measuring means for measuring time based on the change timing of the position sensor signal, and an energizing mode which is a combination of a level indicated by a PWM signal of each phase based on a voltage waveform corresponding to each phase. A storage unit storing electrical angle data indicating a time ratio in which the energizing mode exists as a data table; and an electrical angle stored in the storage unit based on a change time of the position sensor signal measured by the timer unit. Time data conversion means for converting data into time data, and time data obtained by the time data conversion means and the time measured by the time measurement means in order. Comparing means for comparing, voltage signal forming means for sequentially outputting the energization mode corresponding to the time data as a voltage signal in accordance with the timing obtained as a result of the comparison by the comparing means, and a voltage signal from the voltage signal forming means And a driving means for energizing and driving the brushless motor according to the above.

According to this configuration, the electrical angle data stored in the storage means is converted into time data, and the voltage is determined according to the timing obtained as a result of comparing the time data with the time measured by the time measurement means. The energization mode corresponding to the time data is sequentially output from the signal forming means as a voltage signal, and the brushless motor is driven via the driving means. Therefore,
The brushless motor can be driven with low vibration and low noise based on the electrical angle data based on an arbitrary voltage waveform and the energizing mode.

According to a second aspect of the present invention, there is provided a brushless motor driving apparatus comprising: a plurality of position sensors for outputting position sensor signals having a fixed phase relationship with induced voltages generated in a plurality of windings of the brushless motor; Electrical angle data indicating a combination of a timekeeping means for performing timekeeping based on a change timing and a level indicated by a PWM signal of each phase based on a voltage waveform corresponding to each phase, and a time ratio in which the powering mode exists. A storage means in which is stored as a data table, and a time data conversion means for converting the electrical angle data stored in the storage means to time data based on the change time of the position sensor signal measured by the time measurement means, Output data conversion means for converting the energization mode stored in the storage means into output data based on the change time of the position sensor signal Comparing means for sequentially comparing the time data obtained by the time data converting means with the time measured by the time measuring means, and outputting the output data corresponding to the time data according to the timing obtained as a result of the comparison by the comparing means. It is characterized by comprising voltage signal forming means for sequentially outputting as a signal, and driving means for energizing and driving the brushless motor in accordance with the voltage signal from the voltage signal forming means. With this configuration, the capacity of the data table stored in the storage unit can be reduced.

Based on an externally applied voltage command,
A voltage control unit that combines a zero vector signal with a voltage signal and outputs the resultant signal to a driving unit may be provided. With such a configuration, the brushless motor is driven at a speed according to a voltage command. ).

[0025] The storage means stores a plurality of data tables each representing an energization mode and electrical angle data of a PWM signal created based on a carrier having a different frequency with respect to the same voltage waveform, according to the driving state of the brushless motor. In addition, the brushless motor may include a selection unit that selects one of the plurality of data tables. With this configuration, the brushless motor is driven based on the optimum data table selected according to the driving state. (Claim 4).

The output data conversion means may have a configuration having a plurality of conversion patterns having different reference phases, and selectively using the plurality of conversion patterns in accordance with predetermined conditions. It is possible to cope with a case where the mounting position of the position sensor is different (claim 5).

It is preferable that the voltage waveform corresponding to each phase is a sine wave. With such a configuration, torque fluctuation and vibration of the brushless motor are further reduced (claim 6). It is preferable that the data table stored in the storage means has an electrical angle of 30 degrees of the voltage waveform. With such a configuration, the capacity of the data table is minimized (claim 7).

When the brushless motor is started, a switching means for outputting a rectangular wave signal of a 120-degree conduction method to the driving means and, when a predetermined condition is satisfied, switching to a voltage signal from the voltage signal forming means and outputting to the driving means. It is preferable that the brushless motor be started reliably.

The timer means, the storage means, the time data conversion means, the comparison means, the voltage signal forming means (Claim 9), and the output data conversion means (Claim 10)
In addition, it is preferable that the voltage signal forming means is constituted by a one-chip microcomputer (claim 11). With such a constitution, the whole is constituted small and inexpensive.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. 1 to 3, the same parts as those in FIG. 19 are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described below. 1 to 3 showing an electrical configuration, a Hall IC 20 as a position sensor, which is a position sensor disposed at an electrical angle of 120 degrees in a brushless motor (hereinafter, simply referred to as a motor) 8, that is, 20.
Output terminals of u, 20v and 20w are connected to an input terminal of a microcomputer 21 and an input terminal of an interrupt signal generating circuit 22.

The Hall ICs 20u, 20v, 20w detect the rotational position of the permanent magnet type rotor of the motor 8, and correspond to the corresponding U, V, W phase windings 8u, 8v, 8w.
Generates output signals (position sensor signals) Hu, Hv, Hw (see FIG. 14 (b)) having a 30 degree electrical angle delay with respect to the induced voltages vmu, vmv, vmw of w (see FIG. 14 (a)). It is supposed to.

As shown in FIG. 2, the interrupt signal generating circuit 22 includes NOT gates 22a to 22c and an AND gate 2
2d to 22f and an OR gate 22g, and rises when any one of the output signals Hu, Hv, Hw of the Hall ICs 20u, 20v, 20w rises,
When one of them falls, a falling signal Sh is output. The output terminal of the interrupt signal generating circuit 22 is connected to the interrupt signal input terminal of the microcomputer 21 so that the output signal Sh is given as an interrupt signal. The microcomputer 21 recognizes the interrupt at both the rising edge and the falling edge of the interrupt signal Sh.

A clock signal ck of a predetermined frequency is supplied to a clock input terminal of the counter 23 serving as a time measuring means from an oscillation circuit (not shown), and a reset signal Sr is supplied to the reset input terminal from the microcomputer 21. . The 16-bit data bus from which the count data Dc of the counter 23 is output is connected to the input port of the microcomputer 21 and one input data bus of the comparator (comparing means) 24.

The other input data bus (16 bits) of the comparator 24 is connected to an output port of the microcomputer 21. The microcomputer 21 outputs 16-bit data Dt from the output port. When the data Dc and Dt supplied to both input data buses match, a match signal Sc is output to the microcomputer 21. Then, the microcomputer 21 outputs the voltage signals Vu, Vv
, Vw and the zero vector selection signal Sz to the voltage control circuit (voltage control means) 25,
ue, Vve and Vwe are output to the gate circuits 26u, 26v and 26w. The above voltage signals Vu, Vv and Vw, and on / off signals Vue and Vv
e and Vwe and the zero vector selection signal Sz are output data Dm.

FIG. 3 shows a detailed electrical configuration of the voltage control circuit 25. In FIG. 3, voltage command data Dv supplied from the outside is supplied to one input data bus of comparison circuit 25a. The output data bus of the up / down counter 25b is connected to the other input data bus of the comparison circuit 25a, so that a triangular wave signal Ds is supplied.

The triangular wave signal Ds is used by an up / down counter 25b to count up / down by, for example, 50 μm.
This is a signal output by repeating at s cycles. Then, the comparison circuit 25a compares the level of the voltage command data Dv with the level of the triangular wave signal Ds, and
Is output to the gate circuit 25c when the PWM signal becomes a high level when the level is higher, that is, a zero vector signal Sp.

The gate circuit 25c includes the following gates. The zero vector signal Sp is supplied to the negative logic input terminal of the AND gate 25ca and one input terminal of the negative logic AND gate 25cb, and the positive logic input terminal of the AND gate 25ca and the AND gate 25c
The other input terminal b is supplied with a zero vector selection signal Sz. AND gate 25cc,
Voltage signals Vu, Vv and Vw are respectively inputted to one input terminal of 25cd and 25ce, and an output signal of the AND gate 25cb is commonly inputted to the other input terminal.

OR gates 25cf, 25cg and 25c
h input terminals are connected to AND gates 25cc and 25cc, respectively.
The output signals of cd and 25ce are respectively input, and the output signal of the AND gate 25ca is commonly input to the other input terminal. The above is the gate circuit 25c
Is composed.

The output signals of the OR gates 25cf, 25cg and 25ch, which are the output stages of the gate circuit 25c, are supplied to the gate circuits 26u, 26v and 26w as voltage signals Vdu, Vdv and Vdw, as shown in FIG. It has become. The U-phase will be described below. The gate circuit 26u includes a two-input AND gate 26up and a two-input AND gate 26 having one input terminal of negative logic.
un. The voltage signal Vdu is supplied to one input terminal of the AND gate 26up and the AND gate 26un.
, And both AND gates 26 up
And 26un are supplied with an on / off signal Vue output from the microcomputer 21.

Then, AND gates 26up and 26u
n is connected to the gate drive circuit 18u of the drive circuit 19.
p and 18un (not shown in FIG. 1, see FIG. 19) are connected to input terminals, respectively, and the AND gates 26up and 26un output drive signals Dup and Dun to the gate drive circuits 18up and 18un, respectively. It has become. The gate circuit 26v for the V and W phases
And 26w are also configured based on the same principle as that of the U-phase gate circuit 26u.

The microcomputer 21 has a ROM 21a therein.
(Storage means), and the ROM 21a stores a basic data table shown in FIG. The basic data table stores electrical angle data A0 to A13 and energization modes M0 to M13 for 14 storage areas.

FIGS. 5 and 6 show the electrical angle data A0 to A1.
FIG. 3 is a waveform diagram for explaining No. 3 and energization modes M0 to M13. FIG. 5 shows U and V each having a phase difference of 120 degrees.
And the W-phase sine wave signals Su, Sv, and Sw, and a triangular carrier signal having a period 1/27 that of these sine wave signals Su, Sv, and Sw and having an amplitude larger than the sine wave signals Su to Sw. St is superimposed and shown.

The signals Qu, Qv, and Qw indicate high levels when the levels of the sine wave signals Su, Sv, and Sw are higher than the level of the carrier signal St, respectively.
It is a PWM signal based on a sine wave. In FIG. 5, electrical angle regions (hereinafter, simply referred to as regions) 0 to 11 obtained by dividing one electrical cycle of 360 degrees into 12 units of 30 degrees are assigned.

FIG. 6 is a view showing the electric angle 30 to 90 in FIG.
FIG. 2 shows the degree regions 1 and 2 in an enlarged manner. For example,
Looking at the area 1, the PWM signals Qu, Qv and Qw
Is a 3-bit signal, and the level change is represented by high (H) or low (L), the number of times any one of the levels of the 3-bit signal changes is 14 times, Expressed as M13. Also, the energizing modes M0 to M0
The modes of the level change appearing in M13 are the following four patterns, and these four patterns are made to correspond as follows by a 2-bit signal. When Qu, Qv, Qw = L, L, L, the energization mode:
When 00 Qu, Qv, Qw = H, L, L, the energizing mode:
01 Qu, Qv, Qw = H, L, H, energization mode:
In the case of 10 Qu, Qv, Qw = H, H, H, the conduction mode:
11

In the storage areas of the conduction modes M0 to M13 of the basic data table (data table) shown in FIG. 4, any one of the above four conduction modes is stored in two bits.
Also, the electrical angle data A0 to A13 in the basic data table
When the electrical angle of 30 degrees is represented by “256”, the ratio of the electrical angle occupied (existing) by each of the conduction modes M0 to M13, that is, the pulse width of each of the conduction modes M0 to M13 is 6 What is represented by bits is stored. The storage capacity required in this case is (6 + 2) × 14 = 112
(Bit).

FIG. 7 is an output data conversion table stored in the ROM 21a. This output data conversion table shows that the output data D to be output for the energization modes M0 to M13 in each of the areas 0 to 11 divided by the level indicated by the position sensor signals Hu, Hv, Hw.
m, ie, voltage signals Vu to Vw and on / off signal Vu
e to Vwe and the level of the zero vector selection signal Sz.

That is, as described above, the conduction modes M0 to M
13 have four patterns (in any area), but each of the areas 0 to 11 differs from the energization mode array determined by the basic data table.
Since the level patterns of the corresponding voltage signals Vu to Vw are different, they are compared by this output data conversion table. Note that the selection flag SF is, as described later,
This flag is set to "1" when the area is an even number in order to distinguish two areas forming a pair.

The microcomputer 21 has a RAM 21 inside.
In the initial processing, the control program, the basic data table, the output data conversion table, and a rectangular wave data table for outputting a rectangular wave voltage described later are transferred in the ROM 21a. Are read from the RAM 21b in actual processing. Further, a work area for the microcomputer 21 is provided in the RAM 21b, and an output data table is created and used as described later. The above constitutes the driving device.

Next, the operation of the present embodiment will be described with reference to FIGS. FIG.
3 shows a flowchart of a main routine in the control contents of FIG. This main routine is, for example, 20
The processing is performed in a cycle of m seconds.

First, step A1 for determining "start condition?"
, The microcomputer 21 determines whether or not the start condition is satisfied with reference to an input terminal to which a start signal (not shown) is externally supplied.

If the start signal is not supplied from the outside and the microcomputer 21 determines "NO" in the determination step A1, the process proceeds to the "stop signal output" processing step A2, where the on / off signals Vue, Vve and Vwe are output. All are set to low level (L). In this case, no drive signal is supplied to the gate drive circuit 18. Then, the processing shifts to the next processing step A3 of “start flag = L” and the microcomputer 2
When the start flag is set to "L" by writing "0" to the start flag storage area of the RAM 21b, the process returns to step A1.

When the microcomputer 21 determines "YES" in the determination step A1 by receiving the start signal, the process shifts to the processing step A4 of "start processing". This processing step A4 is a step that is executed only once when the motor 8 is started. At the same time, the acceptance of the interrupt signal Sh is permitted, and at the same time, the interrupt processing by the interrupt signal Sh is executed by software. Next, the process proceeds to a determination step A5 of “predetermined rotation angle?”.

At decision step A5, the microcomputer 21
Is the rotation angle N of the motor 8 detected in step B9 of the interrupt processing routine based on the interrupt signal Sh, which will be described later, from the time point of determining “YES” in step A1.
It is determined whether or not m has reached a predetermined value. In the state immediately after the start, the microcomputer 21 determines “NO” and proceeds to step A.
Return to 1.

Next, reference is made to FIG. FIG. 11 shows a flowchart of an interrupt processing routine based on the interrupt signal Sh. First, in the processing step B1 of “input of count data Dc”, the microcomputer 21 reads the count data (timed time) Dc of the counter 23 and sets it as a position sensor signal change time (hereinafter, referred to as change time) Tm. It is stored in the RAM 21b. And
The process shifts to the processing step B2 of “output of reset signal Sr” to output the reset signal Sr to the counter 23 and reset (zero clear) the counter 23. Next, the processing shifts to processing step B3 of “position sensor signal input”.

In processing step B3, the microcomputer 21
Reads the level of each of the position sensor signals Hu, Hv, and Hw, and executes a processing step B of “electrical angle → time data conversion”.
Move to 4. In processing step B4, the microcomputer 2
1 is a basic data table on the RAM 21b while incrementing the variable n from 0 to 27 (FIG. 4)
The electrical angle data A0 to A13 are converted into time data T (n) by sequentially calculating as follows. T (n) = (Tm / 2) × (A (n) / 256) n = 0 to 13 T (n) = (Tm / 2) × (A (27−n) / 256) n = 14 to 27

That is, the change time Tm is the interval of generation of the interrupt signal Sh generated every 60 electrical degrees, and the electrical angle data A0 to A13 indicate the respective energizing modes when the electrical angle 30 degrees is "256". Since the ratio of the electrical angle width of M0 to M13 is shown, for n = 0 to 13, the electrical angle data A0 to A13
13 is directly converted to time data.

As shown in FIG. 6, n = 14 to 27
Since the electrical angle width is symmetrical with respect to the electrical angle data A0, A1,..., A13 with respect to the electrical angle of 60 degrees, n = 14, 15,. , A13, A12,..., A0
Is converted to time data. Then, the calculated time data T (n) is stored in the RAM 21b shown in FIG.
The data is written into the upper output data table, and the process shifts to the next processing step B5 of “energization mode → output data conversion”. Step B4 corresponds to time data conversion means.

The permutation of the time ratios developed as time data A0 to A27 in this output data table is equivalent to the electrical angle data A0 to A1 defined in the basic data table.
The third attribute is determined in the same manner even when the area is different.

In the processing step B5, the microcomputer 21
Reads the energization modes M0 to M13 of the basic data table on the RAM 21b while incrementing the variable n from 0 to 27 as in step B4. Then, the position sensor signals Hu, H read in step B3
When the 7-bit output data Dm corresponding to the energization modes M0 to M13 is read in the area of the output data conversion table corresponding to the levels of v and Hw, the output data D (n) is written and stored in the output data table. That is, the following equation: D (n) = selection {(Hu, Hv, Hw), M (n), SF = 0} n = 0 to 13 D (n) = selection {(Hu, Hv, Hw), M ( 27-n), SF = 1｝ n = 14 to 27, and the energization mode M0 corresponding to n = 0 to 27
To M13 are converted by selecting each of the 48 data Dm in the output data conversion table, output data D0 to D27 are determined, and written to the output data table on the RAM 21b. Next, the process proceeds to a determination step B6 of “start flag = H?”. Step B5 corresponds to output data conversion means.

Here, the reason why the selection flag SF is set to "1" for n = 14 to 27 is, for example, the area 1 in FIG.
Looking at the relationship between 2 and 2, the levels of the PWM signals Qu to Qw indicated by the energization mode assigned to the area 2 are different from the levels indicated by the energization mode of the area 1, so that the output signals are converted. This is to distinguish them in the table.

At the decision step B6, the microcomputer 21
Indicates that the start flag is set (H level)
It is determined whether or not. Immediately after the start of the motor 8, the start flag has been reset in step A3 and is "L", so the microcomputer 21 determines "NO" and shifts to the processing step B7 of "square wave voltage signal output".

In processing step B7, the microcomputer 21
Are the position sensor signals Hu, H read in step B3.
The level of the output data Dm according to the levels of v and Hw is
The data is read from the rectangular wave data table shown in FIG. At this time, the zero vector selection signal S
Since z is always at the low (L) level, the voltage control circuit 2
5, the zero vector signal Sp output from the comparison circuit 25a.
Are not combined with the voltage signals Vu to Vw.

In this case, the drive signals Dup, Dun, Dv
p, Dvn, Dwp, Dwn are position sensor signals Hu,
Output is performed as shown in FIG. 13B according to the level change of Hv and Hw. The positive and negative transistors T1 to T6 of the inverter main circuit 7 are turned on / off by these drive signals, so that the drive device operates the motor based on a 120-degree rectangular wave energization signal corresponding to the position sensor signals Hu to Hw. Drive 8 to start. Next, the process proceeds to the processing step B9 of “rotation angle detection”.

In processing step B9, the microcomputer 21
Increments a rotation angle counter Nm which is a software counter on the RAM 21b (Nm = Nm + 1). The rotation angle counter Nm is incremented every time the interruption processing routine based on the interruption signal Sh is executed, that is, every time the motor 8 rotates 60 degrees. Then, the process returns to the main routine.

As described above, the interrupt signal Sh changes every time one of the output signals (position sensor signals) Hu, Hv, Hw of the Hall ICs 20u, 20v, 20w as position sensors changes. Therefore, thereafter, the interrupt processing (Sh) is executed every time the motor 8 rotates 60 degrees.

Thereafter, when the rotation angle Nm of the motor 8 reaches a predetermined value and the microcomputer 21 determines "YES" (determines that the predetermined condition is satisfied) in the determination step A5 of the main routine, "start flag = H" Processing step A6
Then, the start flag is set to the H level, and the process proceeds to the next step.

Then, step B of the interrupt processing (Sh)
When the microcomputer 21 determines “YES” in 6, the process shifts to the processing step B8 of “switching process”.
In processing step B8, the microcomputer 21
The counter OC, which is a software counter set on 1b, and the comparison time data Dt are reset, and an interrupt by the interrupt signal Sc and an interrupt processing routine are forcibly executed by software.
Steps A5, A6 and B6 correspond to switching means.

FIG. 12 is a flowchart showing the control contents of the interrupt processing routine based on the interrupt signal Sc. In FIG. 12, first, in the processing step C1 of “output of output data Dm”, the microcomputer 21 sets the counter OC
When the output data D (n) is read from the output data table with the count value of
(N) is output as Dm. Then, the process proceeds to the processing step C2 of “calculation of comparison time data Dt”.

In processing step C2, the microcomputer 21
Reads the time data T (n) from the output data table and calculates the comparison time data Dt by the following equation. D
t = Dt + T (n) and the next “comparison time data Dt
When the comparison time data Dt is output to the comparator 24 and set, the process proceeds to the processing step C4 of "Increment of the counter OC". In processing step C4, the microcomputer 21 returns to the main routine after incrementing the counter OC.

In step C3, when the microcomputer 21 sets the comparison time data Dt in the comparator 24, and the time corresponding to the comparison time data Dt has elapsed since the counter 23 was reset in step B2, the comparator 24 starts to operate. By outputting an interrupt signal Sc to the microcomputer 21, the next interrupt process (Sc) is performed.

Therefore, the interruption by the interruption signal Sh is 1
Each time it occurs, the interruption by the interruption signal Sc occurs 27 times, and when the forced execution in step B8 is added once, the total is 28 times. That is, as shown in FIG. 14C, the position sensor signals Hu, Hv and Hw (FIG.
With reference to (b)), by expanding the energizing mode and the energizing mode time width data of 14 points corresponding to the electrical angle of 30 degrees stored in the data table 1 with respect to the electrical angles at 60-degree intervals obtained by (2). Voltage signals Vu, Vv and Vw for the 28 electrical angles are obtained and output to the voltage control circuit 25. These voltage signals Vu, Vv
And Vw are the induced voltage v of the motor 8 shown in FIG.
According to mu, vmv and vmw, the pulse width smoothly changes according to the voltage ratio of the sine wave.

FIG. 15 is an enlarged view of FIG. 14 with respect to regions 1 and 2 (electrical angles of 30 to 90 degrees).
At an electrical angle of 30 degrees, an interrupt occurs due to the interrupt signal Sh. In steps B4 and B5, electrical angle data and energization mode corresponding to the area are read from the basic data table, converted into time and voltage data, and output data tables. Is set to

Thereafter, step C3 of the interrupt processing (Sc)
Each time the time data Dt set in step (c) matches in the comparator 24, an interrupt is generated by the interrupt signal Sc (see (c)), and is stored in the RAM table according to the count value n of the counter OC incremented in step C4. Set time and output data T (n) and D
(N) are read out and sequentially output to the voltage control circuit 25. For example, in the sixth interrupt processing (Sc),
The level “L”, “L” of the data D6 only during the time T6
And "L" voltage signals Vu, Vv and Vw. Steps C1 to C4 correspond to voltage signal forming means.

The voltage control circuit 25 supplies the voltage signals Vu, Vv
And Vw are provided together with the zero vector selection signal Sz, by synthesizing these signals with the zero vector signal Sp (having a pulse width corresponding to the level of the voltage command data Dv) output from the comparison circuit 25b, The voltage-controlled voltage signals Vdu, Vdv, and Vdw are output to the gate circuits 26u, 26v, 26w.

Here, as shown in FIG. 7, the zero vector selection signal Sz has a high "H" level among the voltage signals Vu, Vv and Vw (that is, whether the number of "L" is 0 or not). 1
) Is “H”, and when “L” is large (that is,
(When the number of “H” is 0 or 1) is set to “L”.

The gate circuit 25c of the voltage control circuit 25
If the level of the signal Sz is “H”, when the level of the signal Sp is “H”, the levels of the voltage signals Vdu, Vdv and Vdw are all “H” regardless of the levels of the voltage signals Vu, Vv and Vw. When the level of the signal Sp is "L", the level of the signal Sp is inverted and combined with the voltage signal Vu, Vv or Vw whose level indicates "L".

If the level of the signal Sz is "L" and the level of the signal Sp is "L", the voltage signals Vu, V
Voltage signals Vdu, Vd regardless of the levels of v and Vw
The levels of v and Vdw are all output as “L”,
When the level of the signal Sp is "H", the voltage data Vu, V
Among the signals v and Vw, the signal Sp whose level indicates “H” is inverted and synthesized (FIG. 16D)
reference).

That is, when the levels of the voltage data Vu, Vv and Vw are all "H" or "L", the inverter main circuit 7 is not energized.
There is no need to combine the zero vector signal Sp with u, Vv and Vw. Therefore, the above operation of the voltage control circuit 25 suppresses unnecessary switching operation from being performed in the inverter main circuit 7.

As described above, the voltage signals Vdu, Vdv and Vdw output from the voltage control circuit 25 are output together with the on / off signals Vue, Vve and Vwe (in this case, all "H") output directly from the microcomputer 21. , Gate circuits 26u, 26v and 26w, respectively. Then, the gate circuits 26u, 26v, and 26w output non-inverted signals of the voltage signals Vdu, Vdv, and Vdw to the drive circuit 19 as drive signals Dup, Dvp, and Dwp, and inverted signals as drive signals Dun, Dvn, and Dwn. You.

Then, the inverter main circuit 7 sends the drive signal to each transistor T 1 via the gate drive circuit 18.
To T6, the motor 8 is driven by applying a sinusoidal conduction signal to the windings 8u, 8v and 8w.

As described above, according to the present embodiment, the electrical angle 30 obtained by comparing the voltage waveforms of the three-phase sine wave signals Su to Sw and the triangular wave signal St having a 1/27 cycle thereof is obtained. A basic data table in which the PWM signals corresponding to degrees are represented by the conduction modes M0 to M13 and the electrical angle data A0 to A13, and the conduction modes M0 to M13 are converted into the voltage data Vu, Vv according to the area obtained by dividing one electric cycle into 12 equal parts. , Vw
Is stored in the ROM 21a. The microcomputer 21 determines the count value Dc of the counter 23 in the interrupt processing (Sh) generated every 60 electrical degrees.
The electric angle data A0 to A13 are converted into time data T0 to T27 for an electric angle of 60 degrees based on the above, and the energization modes M0 to M13 are converted into output data D0 to D27 by the conversion table. Then, the count value of the counter 23 and the time data T0 to T2 set in the comparator 24 are obtained.
7, the output data D0 to D27 are sequentially output from the voltage signals Vu to V27 in the interrupt processing (Sc) generated every time
By outputting the signal as w, an energization signal based on a sine wave is applied to the windings 8 u to 8 w of the motor 8 via the voltage control circuit 25 and the drive circuit 19 to drive the motor 8.

Accordingly, it is possible to reduce the torque fluctuation and vibration of the motor 8, to drive the motor 8 with high efficiency, and to store the voltage ratio data based on the sine wave in the storage means, Compared to the conventional method of reading data sequentially and energizing the motor winding, ROM
The capacity of the data stored in the memory 21a can be greatly reduced by minimizing it (960 bits → 112 bits).

According to the present embodiment, the voltage control circuit 2
5 is given for given voltage signals Vu, Vv, Vw.
Since the voltage signals Vdu, Vdv, and Vdw are output by synthesizing the zero vector signal Sp based on the voltage command data Dv according to the level of the zero vector selection signal Sz, the motor 8 is driven at a speed corresponding to the voltage command data Dv. When the voltage data Vu to Vw are all “H” or “L” and the windings 8u to 8w of the motor 8 are not energized, the transistors T1 to T1 in the inverter main circuit 7 Efficiency can be improved by reducing unnecessary switching operation of T6.

Further, according to the present embodiment, when the motor 8 is started, the microcomputer 21 reads out the output data Dm from the rectangular wave data table stored in the ROM 21a, outputs the output data Dm to the voltage control circuit 25, and rotates the motor 8 When the number of angles becomes equal to or larger than a predetermined value, the electric angle data A0 to A13 read from the basic data table and the output data Dm based on the conduction modes M0 to M13 are switched and output, so that the motor 8 can be started reliably. .

The present invention is not limited to the embodiment described above and shown in the drawings, and the following modifications or extensions are possible. Induced voltages vmu to vm of motor 8
Although the voltage signals Vu to Vw corresponding to the sine wave having the same phase as w are output, the mounting positions of the Hall ICs 20 u to 20 w are adjusted according to the time constant of the windings 8 u to 8 w of the motor 8. The induced voltages vmu to vmw
And the phases of the current waveforms of the windings 8u to 8w are made in-phase, whereby the efficiency can be further improved. In addition, microcomputer 2
In the process (1), the voltage data Vu to Vw may be output in consideration of the phases corresponding to the time constants of the windings 8u to 8w.

For example, to advance the voltage phase by 60 electrical degrees, the phase of the basic data table shown in FIG.
Processing may be performed based on the basic data table shown in FIG. 17 advanced by 0 degrees (that is, for one area). Also, in order to advance the voltage phase by 30 electrical degrees, the phase of the basic data table in FIG. 4 is advanced by 30 electrical degrees (that is, for a half area), and processing is performed based on the basic data table shown in FIG. Should be done. A plurality of basic data tables having different reference phases are stored in the ROM 21a and are selected by different motors or selected by conditions such as the number of rotations of the motor and the load torque, thereby achieving more efficient driving. It can be performed.

The data of the basic data table stored in the ROM 21a is not limited to that shown in FIG. 4, and may be created by appropriately changing the ratio of the period between the voltage waveform and the carrier. Further, a plurality of basic data tables based on PWM signals generated by the sine wave signals Su to Sw having different carrier wave periods are stored in the ROM 21a, and are stored in the ROM 21a in accordance with, for example, the rotation speed (drive state) of the motor 8. Selection means for selecting may be provided. With such a configuration,
When the number of rotations is low, torque fluctuation can be further reduced by selecting a basic data table corresponding to a short carrier wave cycle.

The control program and various data tables stored in the ROM 21a may be read directly from the ROM 21a without being transferred to the RAM 21b. With such a configuration, the capacity of the RAM 21b can be reduced. The voltage waveform is not limited to a sine wave, and may be any voltage waveform that reduces torque fluctuation and vibration of the motor 8. The interrupt signal generation circuit 22 may be configured inside the microcomputer 21. A one-chip microcomputer may be configured by adding a counter 23 and a comparator 24 to the microcomputer 21 of the present embodiment. Furthermore,
The voltage control circuit 25 and the logic circuit 26 may be added to form a one-chip microcomputer. With such a configuration, the drive device can be reduced in size and cost.

On / off signal V of output data conversion table
Since ue to Vwe are all “H”, step C
In step 1, the "H" level may be output uniformly. By doing so, the area of the on / off signals Vue to Vwe can be deleted from the output data conversion table and the output data table, and the capacity of both is 3 × 48 = 1.
It can be reduced by 44 bits, 3 × 28 = 84 bits.

In step B5, the energizing modes M0 to M0
When converting M13 into output data D (n), n = 14
27, the output data Dm may be read out by contrasting the output data Dm obtained by inverting the two bits of the conduction mode with the selection flag SF = 0 in the output data conversion table.
Here, the meaning of “contrast two bits of the conduction mode inverted” is that if the conduction mode M (n) is “00, 01, 10, 11” at n = 14 to 27, When n = 0 to 13, "11, 10, 0"
This means that the output data Dm is read out as being 1,00 ". With this configuration, the capacity of the output data conversion table can be reduced to half.

The basic data table is not limited to storing the energization mode and the electrical angle data for the electrical angle of 30 degrees, but may store the data for the electrical angle of 360 degrees. in this case,
If the levels indicated by the PWM signals Qu to Qw are directly stored instead of the energization mode, the output data conversion table becomes unnecessary. In the case of such a configuration, an extra storage capacity of the storage means is required, but a process of converting the energization mode into the output data is not required, and the processing load of the software can be reduced.

When switching from a voltage signal based on a square wave at the time of starting the motor 8 to a voltage signal based on a sine wave during normal operation, the switching is performed when the rotation angle of the motor 8 reaches a predetermined rotation speed as a predetermined condition. However, in the interrupt processing routine based on the interrupt signal Sh, the number of rotations of the rotor is measured by counting the number of interrupts.
The switching may be performed when the number of rotations exceeds a predetermined value. Alternatively, the switching may be performed after a predetermined time has elapsed. Further, the switching may be performed when the rotation angle of the motor 8 reaches a predetermined rotation angle number. The execution cycle of the main routine is not limited to 20 ms and may be changed as appropriate. The up / down cycle of the zero vector signal Sp is not limited to 50 μs and may be changed as appropriate. The counter 23 is reset every time the interrupt processing routine (Sh) is executed (electrical angle 60 degrees).
But the electrical angle 120, 180 or 3
It may be performed every 60 degrees.

[0093]

Since the present invention is as described above,
The following effects are obtained. According to the brushless motor driving device of the present invention, the energization mode, which is a combination of the levels indicated by the PWM signals of the respective phases based on the voltage waveform, and the electrical angle data indicating the time ratio in which the energization mode exists are data. The voltage signal forming means is stored in the storage means in advance as a table, and the output data corresponding to the time data is sequentially converted into a voltage signal in accordance with the timing data obtained as a result of the comparison between the time data by the comparing means and the time measured by the timing means. Since the brushless motor is output by energizing and driving the brushless motor to drive the brushless motor, it is possible to reduce the data capacity required for the storage unit as compared with the prior art, and to set the electrical angle data and the energizing mode based on an arbitrary voltage waveform. , It can be driven with low vibration and low noise, and with high efficiency.

According to the brushless motor driving device of the present invention, the electrical mode which is a combination of the level indicated by the PWM signal of each phase based on the voltage waveform and the electrical angle data indicating the time ratio in which the electrical mode exists. Are stored in the storage means in advance as a data table, the electrical angle data and the conduction mode are converted into time data and output data, respectively, and the voltage signal forming means compares the time data by the comparing means with the time measured by the time measuring means. According to the timing obtained as a result, the output data corresponding to the time data is sequentially output to the driving means as a voltage signal to drive the brushless motor, so that the capacity of the data table can be reduced.

According to the third aspect of the present invention, the voltage control means combines the voltage signal with the zero vector signal based on the externally applied voltage command and outputs the resultant signal to the driving means. , The brushless motor can be driven.

According to the brushless motor driving device of the fourth aspect, the selecting means converts the PWM signal generated based on the carrier having a different frequency for the same voltage waveform according to the driving state of the brushless motor. Since one of the plurality of data tables is selected, the brushless motor can be driven more efficiently based on the optimum data table selected according to the driving state.

According to the brushless motor driving device of the present invention, the output data conversion means selectively uses a plurality of conversion patterns having different reference phases in accordance with predetermined conditions. It is possible to cope with different cases.

According to the brushless motor driving device of the sixth aspect, since the voltage waveform is a sine wave, the brushless motor can be driven with lower vibration and lower noise.

According to the brushless motor driving device of the present invention, since the data table of the storage means represents only the electrical angle of 30 degrees of the voltage waveform, the capacity of the data table is minimized. be able to.

According to the driving device for a brushless motor according to the eighth aspect, the switching means outputs a rectangular wave signal of a 120-degree conduction type to the driving means when the brushless motor is started, and forms a voltage signal when a predetermined condition is satisfied. Since the voltage signal is switched to the voltage signal from the means and output to the driving means, the brushless motor can be reliably started.

According to the brushless motor driving device according to the ninth to eleventh aspects, the clocking means, the storage means, the time data converting means, the comparing means, and the voltage signal forming means are provided (claim 9). , Output data converting means (claim 10), and voltage signal forming means (claim 11).
Since it is constituted by a one-chip microcomputer, the whole can be constituted small and at a fixed price.

[Brief description of the drawings]

FIG. 1 is an electrical configuration diagram showing one embodiment of the present invention.

FIG. 2 is an electrical configuration diagram of an interrupt signal generation circuit.

FIG. 3 is a diagram of a voltage control circuit corresponding to FIG. 2;

FIG. 4 is a diagram showing a basic data table.

FIG. 5 is a waveform diagram of a three-phase sine wave and a carrier wave for explaining electrical angle data and a conduction mode stored in a basic data table.

FIG. 6 is an enlarged view of a portion having an electrical angle of 30 to 90 degrees in FIG.

FIG. 7 shows an output data conversion table.

FIG. 8 is a diagram showing a rectangular wave data table.

FIG. 9 shows an output data table.

FIG. 10 is a flowchart showing a main routine.

FIG. 11 is a diagram showing an interrupt process by an interrupt signal Sh;
0 equivalent figure

FIG. 12 is a diagram showing an interrupt process by an interrupt signal Sc;
0 equivalent figure

FIG. 13 is a timing chart when a rectangular wave signal is output.

FIG. 14 is a diagram corresponding to FIG. 13 when a sine wave signal is output.

FIG. 15 is an enlarged view of a portion having an electrical angle of 30 to 90 degrees in FIG. 14;

FIG. 16 is a timing chart showing the operation of the voltage control circuit.

FIG. 17 is a diagram corresponding to FIG. 7 showing a modification.

FIG. 18 is a diagram corresponding to FIG. 17;

FIG. 19 is a diagram corresponding to FIG. 1 showing a conventional technique.

FIG. 20 is a timing chart.

FIG. 21 is a diagram showing sine wave data stored in a memory;

[Explanation of symbols]

8 is a brushless motor, 8u, 8v and 8w are windings,
9 is a drive circuit (drive means), 20u, 20v, 20w are Hall ICs (position sensors), 21 is a microcomputer, 21a is a ROM (storage means), 23 is a counter (clocking means), and 24 is a comparator (comparison means). ) And 25 indicate voltage control circuits (voltage control means).

Claims (11)

[Claims] 1. A plurality of position sensors for outputting a position sensor signal having a fixed phase relationship with an induced voltage generated in a plurality of phases of a winding of a brushless motor, and timing is performed based on a change timing of the position sensor signal. Clocking means, an energizing mode as a combination of levels indicated by PWM signals of respective phases based on voltage waveforms corresponding to the respective phases, and electrical angle data indicating a time ratio in which the energizing mode exists are stored as a data table. Storage means; time data conversion means for converting electrical angle data stored in the storage means into time data based on the change time of the position sensor signal measured by the time measurement means; Comparing means for sequentially comparing the time data obtained by the timer with the time measured by the time measuring means; Voltage signal forming means for sequentially outputting the energization mode corresponding to the time data as a voltage signal in accordance with the timing, and energizing and driving the brushless motor in accordance with the voltage signal from the voltage signal generating means And a driving device for a brushless motor. 2. A plurality of position sensors for outputting a position sensor signal having a fixed phase relationship with induced voltages generated in a plurality of windings of a brushless motor, and a timing device for timing based on a change timing of the position sensor signal. Storage means for storing, as a data table, an energization mode which is a combination of levels indicated by PWM signals of respective phases based on a voltage waveform corresponding to each phase, and electrical angle data indicating a time ratio in which the energization mode exists. Means, time data conversion means for converting electrical angle data stored in the storage means to time data based on a change time of the position sensor signal measured by the time measurement means, and a change in the position sensor signal. Output data conversion means for converting the energization mode stored in the storage means into output data based on time; Comparing means for sequentially comparing the time data obtained by the converting means with the time measured by the time measuring means; and outputting voltage data corresponding to the time data in accordance with the timing obtained as a result of the comparison by the comparing means. A brushless motor driving device, comprising: a voltage signal forming means for sequentially outputting the brushless motor; and a driving means for energizing and driving the brushless motor in accordance with a voltage signal from the voltage signal forming means. 3. A brushless motor according to claim 1, further comprising voltage control means for synthesizing a zero vector signal with a voltage signal based on an externally applied voltage command and outputting the synthesized signal to a driving means. Drive. 4. A brushless motor driving means for driving a brushless motor, wherein the storage means stores a plurality of data tables representing energization modes and electrical angle data of PWM signals created based on carrier waves having different frequencies for the same voltage waveform. 4. The brushless motor driving device according to claim 1, further comprising a selection unit that selects one of the plurality of data tables according to a state. 5. The output data conversion means has a plurality of conversion patterns having different reference phases, and selectively uses the plurality of conversion patterns in accordance with a predetermined condition. 5. The brushless motor driving device according to any one of 4. 6. The brushless motor driving device according to claim 1, wherein a voltage waveform corresponding to each phase is a sine wave. 7. The brushless motor driving device according to claim 2, wherein the data table of the storage means represents only 30 electrical degrees of the voltage waveform. 8. When starting the brushless motor, 120
Switching means for outputting a rectangular wave signal of a current energization type to the driving means, and when a predetermined condition is satisfied, switching to a voltage signal from the voltage signal forming means and outputting the voltage signal to the driving means. 8. The driving device for a brushless motor according to any one of 8 above. 9. The apparatus according to claim 1, wherein the time measuring means, the storing means, the time data converting means, the comparing means, and the voltage signal forming means are constituted by a one-chip microcomputer. A driving device for the brushless motor according to the above. 10. The one-chip microcomputer according to claim 2, wherein the time measuring means, the storing means, the time data converting means, the output data converting means, the comparing means, and the voltage signal forming means are constituted by a one-chip microcomputer. 9. The driving device for a brushless motor according to any one of claims 1 to 8. 11. A one-chip microcomputer comprising: a timer means, a storage means, a time data conversion means, an output data conversion means, a comparison means, a voltage signal forming means, and a voltage control means. The driving device for a brushless motor according to any one of claims 3 to 8.