JPH09233886A - Sensorless motor driving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driving circuit which is suitable for low consumption of power in an equipment such as a headphone stereo which is provided with a sensorless motor. SOLUTION: In a sensorless motor driving circuit which rotates a rotor by switching currents in armature windings 6, 7, 8, induced voltages Eu, Ev, Ew which are generated in the armature windings 6, 7, 8 due to rotation of a sensorless motor are compared with a reference voltage 19 by comparators 16, 17, 18. By letting transistors 20, 21, 22 conduct according to the output signals Su, Sv, Sw of the comparators 16, 17, 18, current is prevented from being supplied to a current amplifier circuit 4 from a voltage/current converting circuit 3 during a period when the armature windings 6, 7, 8 do not conduct. By this method, unnecessary current in the armature windings 6, 7, 8 is eliminated and acoustic noise and spike noise are suppressed and low consumption of power is accomplished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensorless motor driving circuit for half-wave driving a sensorless motor of, for example, three phases used as a rotational driving motor for headphone stereos, floppy disks, hard disks and the like.

[0002]

2. Description of the Related Art In recent years, sensorless motors that do not require a position detector have been widely used in headphone stereos and the like due to downsizing and thinning of devices. less than,
A conventional sensorless motor drive circuit using a three-phase half-wave drive sensorless motor will be described. FIG. 2 is a block diagram showing the configuration of a conventional sensorless motor drive circuit. In FIG. 2, 1 is a logical operation circuit, 2 is a trapezoidal wave generation circuit, 3 is a voltage / current conversion circuit, 4 is a current amplification circuit, 5
Is a frequency / voltage conversion circuit, 6, 7 and 8 are armature windings of a sensorless motor, 9, 10 and 11 are output transistors,
Reference numerals 12, 23, 24 and 25 are comparators, 14 is a speed command input terminal, and 15 is a power supply voltage terminal.

FIG. 3 shows a conventional sensorless motor drive circuit.
The waveform diagram showing the signal waveform at each point of
Induced voltage E on lines 6, 7, and 8_U, E_V, E_WAnd comparator 2
Output signal A of 3, 24, 25_U, A_V, A_WAnd a logical performance
Output signal B of arithmetic circuit 1_U, B _V, B_WAnd the trapezoidal wave generation time
Trapezoidal wave voltage C of path 2_U, C_V, C_WAnd voltage / current conversion
Trapezoidal wave current D of circuit 3_U, D_V, D_WAnd frequency / voltage
The output voltage Va of the conversion circuit 5 is shown.

FIG. 4 is a circuit diagram showing a specific configuration of the U-phase portion of the trapezoidal wave generation circuit 2, and the remaining V-phase and W-phase have the same configuration as the U-phase. In FIG. 4, 26, 2
7, 28 and 29 are transistors, and 30 is a current 2
A constant current source for flowing I ₀ , 31 is a constant current source for flowing a current I ₀ ,
Reference numeral 32 is a reference voltage for clamping, and 33 is a capacitor.

FIG. 5 is a circuit diagram showing a specific configuration of the voltage / current conversion circuit 3. In FIG. 5, 34 to 44 are transistors, and 45 is a constant current source for flowing a current I ₁ . FIG. 10 is a circuit diagram showing a specific configuration of the frequency / voltage conversion circuit 5. In FIG. 10, 51 to 54 are transistors, 55 is a constant current source for flowing a current I ₂ , and 56 to
Reference numerals 59 are resistors, respectively.

FIG. 11 is a characteristic diagram showing the relationship between the induced voltage and the output voltage Va in the frequency / voltage conversion circuit 5.
The operation of the sensorless motor drive circuit configured as described above will be described below. First, a speed command voltage according to a desired speed is externally set to the speed command input terminal 14 of FIG. When the sensor-less motor is activated, the armature winding 6, 7, 8, 120 ° sinusoidal induced voltage in FIG. 3 whose phases are in different around the power supply voltage E _U, E _V, E _W are generated. As the induced voltage E _U, E _V, and E _W as compared to the power supply voltage V _CC applied to the supply voltage terminal 15 by a comparator 23, 24 and 25 in FIG. 2, the output signal A _U in FIG. 3,
Create A _V and A _W.

Output signals A of the comparators 23, 24, 25
_U, A _V, A _W, the induced voltage E _U, becomes a low level when E _V, E _W is higher than the power supply voltage V _CC, respectively, to the high level when less than the power supply voltage V _CC reversed. Output signals A _U , A _V , A of the comparators 23, 24, 25
_W is input to the logical operation circuit 1. This logical operation circuit 1
In the logical product of the negation of the signal A _U and the signal A _V, signal A _V
And the negation of the signal A _W , and the logical product of the AND of the signal A _W and the negation of the signal A _U , and output signals B _U and B
_V and B _W are generated.

The output signal B _U of the logical operation circuit 1,
B _V and B _W have a high level only for a 120 ° period from the rising of the output signals A _U , A _V , and A _W of the comparators 23, 24, and 25, and have a low level for the remaining 240 ° period. The output signals B _U , B _V , B of this logical operation circuit 1
_W is changed to trapezoidal wave voltages C _U , C _V , and C _{W in} which rapid switching is smoothed by the trapezoidal wave generation circuit 2 in order to reduce acoustic noise and spike noise of the sensorless motor.

Here, the trapezoidal wave generating circuit 2 is shown in FIG.
By configuring the circuit as
Output signal B_UDepending on the high level and low level of
Turns on and off the resistor 26 to charge the capacitor 33.
Generate trapezoidal voltage by switching between electric and discharge
doing. Specifically, the output signal B of the logical operation circuit 1_U
Is high level, the transistor 26 is on and constant
Current of source 30 2I₀Flows through the transistor 26
It does not flow to the transistor 27 of the bottom mirror, so
The transistor 28 also has a current I of the constant current source 30.₀Is a conde
Flow into the sensor 33 and charge the capacitor 33 with a constant current.
Output signal C_UThe voltage of rises linearly.
And the output signal C _UIs the voltage of transistor 29
When the sum of the emitter-emitter voltage and the reference voltage 32 is reached,
The transistor 29 becomes conductive and the current I of the constant current source 30₀Is
The output signal C will flow through the transistor 29.
_UVoltage does not rise any further.

When the output signal B _U of the logical operation circuit 1 is low level, the transistor 26 is off and the current 2I ₀ of the constant current source 30 is the current mirror transistor 27.
Therefore, the current 2I ₀ also flows through the transistor 28 of the current mirror. A half current I ₀ of the current 2I ₀ flows from the constant current source 31, the remaining current I ₀ flows from the capacitor 33, the capacitor 33 is discharged at a constant current, and the voltage of the output signal C _U falls linearly. To go. Finally, the voltage drops to the collector-emitter saturation voltage of the transistor 28.

As described above, the maximum value of the voltage of the output signal C _U is determined by the sum of the base-emitter voltage of the transistor 29 and the reference voltage 32, and the minimum value is the collector-emitter saturation voltage of the transistor 28. Depends on. Frequency / voltage conversion circuit 5, for example, when a circuit as shown in FIG. 10, the induced voltage E _U, E _V, the voltage Va proportional to the rotational speed of the sensorless motor from E _W is obtained a point.
The characteristics of the frequency / voltage conversion circuit 5 are shown in the characteristic diagram of FIG.

Here, the frequency / voltage conversion circuit 5 will be described in detail. In FIG. 10, the voltage Va is the resistance 5
When the resistance value of 6 is r ₅₆ and the current flowing through the resistor 56 is I ₅₆ ,

[0013]

## EQU1 ## Va = I ₅₆ × r ₅₆ In addition, the current I ₅₆ flowing through the resistor 56, when the base currents of the transistors 52, 53 and 54 are ignored,

[0014]

## EQU2 ## It is represented by I ₅₆ = I ₅₇ + I ₅₈ + I ₅₉ . However, I ₅₇ , I ₅₈ and I ₅₉ are resistors ₅₇ and 5
This is the current flowing through 8,59. Here, resistors 57 and 5
The currents I ₅₇ , I ₅₈ , and I ₅₉ flowing through 8, ₅₉ are
The resistance value of each of 58 and 59 is r, and the transistor 5
The potentials of the emitters of 2, 53 and 54 are respectively V ₁ ,
When V ₂ and V ₃ ,

[0015]

## EQU3 ## I ₅₇ = (E _U −V ₁ ) / r

[0016]

## EQU4 ## I ₅₈ = (EV- _{V 2} ) / r

[0017]

## EQU5 ## It is represented by I ₅₉ = (E _W -V ₃ ) / r. In addition, in FIG.
Considering the base-emitter voltage V _BE of 1, 52, 53, 54 in the 0.7V approximation, the transistors 52, 53, 5
If 4 is turned on,

[0018]

## EQU6 ## V ₁ = V ₂ = V ₃ = V _CC . Thus, Formula 3, from [Equation 4], [Equation _{5], E U ≦ V I 57 =} 0 becomes the case of _CC, next I ₅₈ = 0 in the case of _{E V ≦ V CC, E W} ≦ V _In the case of _CC , I ₅₉ = 0.

Here, the operation of FIG. 10 is performed by the induced voltage E of FIG.
_U, E _V, in E _W, will be described separately the area from A to G. The induced voltage E _U, E _V, E _W, the power supply voltage V _CC
Since it is a sine wave with reference to, when d is the amplitude and ω is the phase,

[0020]

[Equation 7] E _U = dsin ω + V _CC

[0021]

[Equation 8] E _V = d sin (ω-2π / 3) + V _CC

[0022]

[Equation 9] E _W = d sin (ω + 2π / 3) + V _CC In the region A, since E _V <V _CC , I ₅₈ = 0, V
_{Since 1} = V ₃ = V _CC ,

[0023]

Equation 10] _{I 56 = I 57 + I 59} = (E U + E W -2V CC) / r = d {sin ω + sin (ω + 2π / 3)} / r = - {dsin (ω-2π / 3)} / r = - a _{(E V -V CC) / r} .

In the region B, since E _V <V _CC and E _W <V _CC , I ₅₈ = I ₅₉ = 0 and V ₁ = V _CC are satisfied.

[0025]

## EQU11 ## I ₅₆ = I ₅₇ = (E _U −V _CC ) / r. In the region C, since E _W <V _CC , I ₅₉ = 0, V ₁
= V ₂ = V _CC , so

[0026]

Equation 12] _{I 56 = I 57 + I 58} = (E U + E V -2V CC) / r = d {sin ω + sin (ω-2π / 3)} / r = - {dsin (ω + 2π / 3)} / r = - a _{(E V -V CC) / r} .

In the region D, since I _U <V _CC and E _W <V _CC , I ₅₇ = I ₅₉ = 0 and V ₂ = V _CC .

[0028]

[Number 13] I ₅₆ = I ₅₈ = a _{(E V -V CC) / r} . In the region E, from _{E U <V CC, I 57} = 0, V 2
= V ₃ = V _CC , so

[0029]

Equation 14] _{I 56 = I 58 + I 59} = (E V + E W -2V CC) / r = d {sin (ω-2π / 3) + sin (ω + 2π / 3)} / r = - (dsin ω) / r = - a _{(E U -V CC) / r} .

In the region F, since I _U <V _CC and E _V <V _CC , I ₅₇ = I ₅₈ = 0 and V ₃ = V _CC .

[0031]

(15) I ₅₆ = I ₅₉ = (E _W −V _CC ) / r. In the region G, since E _V <V _CC , I ₅₈ = 0, V ₁
= V ₃ = V _CC , so

[0032]

Equation 16] _{I 56 = I 57 + I 59} = d {sin ω + sin (ω + 2π / 3)} / r = - {dsin (ω-2π / 3)} / r = - and (E _V -V _CC) / r Become.

It should be noted, the induced voltage E _U at a frequency / voltage converter circuit 5, the E _V, the voltage Va proportional to the rotational speed of the sensorless motor from E _W is obtained, the induced voltage E _U, E _V,
This is because the amplitude of E _W is proportional to the rotation speed of the sensorless motor. The voltage Va at the point a, which is the output end of the frequency / voltage conversion circuit 5, is applied to the speed command input terminal 14 by the comparator 12.
The error signal current I _{1 of} FIG. 5 corresponding to the error voltages of the both is compared with the speed command voltage set to the above, and the comparator 12 outputs the error signal current I ₁ . Trapezoidal wave voltage C _U of the trapezoidal wave generation circuit 2,
C _V and C _W are converted by the voltage / current conversion circuit 3 into trapezoidal wave currents D _U , D _V and D _W according to the error signal current I ₁ . Here, for example, the circuit is configured as shown in FIG. 5, and the error signal current I ₁ is distributed to the U phase, the V phase, and the W phase in accordance with the trapezoidal wave voltages C _U , C _V , and C _W. . Here, the circuit operation of FIG. 5 will be described in detail. Current I ₂
Flows through the transistor 43, but the same current flows through the transistor 44 by the current mirror. This current is distributed according to the impedance ratio of the transistors 40 to 42, which impedance ratio is trapezoidal wave voltage C _U , C _V ,
Determined by C _W. Then, the current distributed to the transistor 40 flows through the transistor 34, and the same current flows as the trapezoidal wave current D _U through the transistor 35 by the current mirror. Further, the current distributed to the transistor 41 flows through the transistor 36, and the same current flows as the trapezoidal wave current D _V through the transistor 37 by the current mirror. Further, the current distributed to the transistor 42 flows to the transistor 38, and the same current is passed through the transistor 39 by the current mirror to generate the trapezoidal current D.
_It flows as _W.

The trapezoidal wave currents D _U , D _V and D _W are
The output transistor 7, which is amplified by the current amplifier circuit 4,
These are supplied to the bases 8 and 9, respectively, and the sensorless motor is driven. At this time, the frequency /
The output voltage Va of the voltage conversion circuit 5 is negatively feedbacked, becomes equal to the speed command voltage set in the speed command input terminal 14, and the sensorless motor rotates at a desired speed.

[0035]

However, in the above conventional configuration, when the voltage / current conversion circuit 3 converts the trapezoidal wave voltage into the trapezoidal wave current, an unnecessary minute current is generated in the non-energized phase. There were times when it flowed. This point is shown in Figure 6.
This will be described with reference to FIG. In FIG. 6, the armature winding 6,
7,8 induced voltage E _U of, E _V, E _W and the trapezoidal wave generating circuit 2
Trapezoidal wave voltage C _U , C _V , C _W and voltage / current conversion circuit 3
The trapezoidal wave currents D _U , D _V , and D _W are shown. Also,
V _U is an energized phase (V phase, W
It represents the voltage difference between the phase is not energized and the phase) (U-phase), V _V
Indicates the voltage difference between the energized phase (W-phase, U-phase) and the non-energized phase (V-phase) during energization switching, and V _W is the energized phase (U-phase, V-phase) during energization switching. represents the voltage difference between the phase is not energized and the phase) _{(W-phase), I U, I V,} I W
Indicates unnecessary minute currents in the trapezoidal wave currents D _U , D _V , and D _W.

The minute currents I _U , I _V , I as described above
For example, when the voltage / current conversion circuit 5 is configured as shown in FIG. 5, _W occurs at the time of switching the energization when the voltage difference between the energized phase and the non-energized phase is not sufficient. For example, in a device such as a headphone stereo that requires a low power supply voltage operation, the two factors of low power supply voltage and trapezoidal wave drive are combined, and the energization phase is switched as shown in FIG. At times, the above voltage difference cannot be sufficiently obtained, and unnecessary minute currents I _U , I _V , and I _W flow in the non-energized phase. The unnecessary minute currents I _U , I _V , and I _W are amplified by the current amplification circuit 4,
It flows into the bases of the output transistors 9, 10, and 11,
It works to decelerate the sensorless motor. As a result,
The current consumption increases. This poses a serious problem in devices where low power consumption is desired.

The unnecessary minute currents I _U , I _V ,
To remove I _W , the transistors 34, 3 of FIG.
It is conceivable to insert resistors 46U, 46V, 46W between the bases and emitters of 6, 38 as shown by the broken line. Then, the trapezoidal wave currents D _U , D _V , D of FIG.
_W changes like the substantially trapezoidal wave currents D _U ', D _V ' and D _W 'shown in Fig. 9, and the rising and falling edges of the energization signal become steep, resulting in acoustic noise and spikes generated from the sensorless motor. The noise increases, which is a problem in audio equipment.

Therefore, an object of the present invention is to eliminate the need to try to flow to the armature winding of each phase while the armature winding of each phase is not energized without increasing acoustic noise and spike noise. An object of the present invention is to provide a sensorless motor drive circuit capable of removing current and realizing low power consumption.

[0039]

A sensorless motor drive circuit of the present invention drives an n-phase (n is an integer of 2 or more) sensorless motor in an n-phase half-wave, and has one end commonly connected to a power supply voltage terminal. The n-phase armature windings of the sensorless motor are connected to the other ends of the n-phase armature windings, and the emitters of the output transistors are grounded, and the induced voltage and the power supply voltage generated in the n-phase armature windings. The n induced voltage / power supply voltage comparing means to be compared with each other, the trapezoidal wave converting means for converting the output signals of the n induced voltage / power supply voltage comparing means into the n-phase trapezoidal wave voltage, and the rotation speed of the sensorless motor Frequency / voltage conversion means for generating a proportional speed-corresponding voltage, speed command voltage / speed-corresponding voltage comparing means for detecting an error voltage between a speed command voltage input from the outside and a speed-corresponding voltage, and a trapezoidal wave. Voltage / current conversion means for converting the n-phase trapezoidal wave voltage output from the generating means into an n-phase trapezoidal wave current having a magnitude corresponding to the error voltage and supplying the n-phase trapezoidal wave current to the bases of the n output transistors, respectively, and sensorless. N induced voltage / reference voltage comparison means for comparing the induced voltage generated in the n-phase armature winding of the motor with a predetermined reference voltage,
n output transistors from the voltage / current conversion means during a period in which the induced voltage generated in the n-phase armature winding of the sensorless motor based on the outputs of the n induced voltage / reference voltage comparison means is higher than a predetermined reference voltage. N unnecessary current removing means for interrupting the current supplied to each base.

According to the structure of the present invention, when the sensorless motor rotates, the induced voltage generated in the armature winding is compared with a certain reference voltage by the n induced voltage / reference voltage comparison means, and the sensorless motor is compared. In the period in which the induced voltage generated in the n-phase armature winding is higher than the predetermined reference voltage, the currents supplied from the voltage / current conversion means to the bases of the n output transistors by the n unnecessary current removal means, respectively. By shutting off, it is possible to remove an unnecessary minute current that flows to the armature winding of each phase while the armature winding of each phase is not energized.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a sensorless motor drive circuit of the present invention will be described below with reference to the drawings. FIG.
FIG. 3 is a block diagram showing a configuration of a sensorless motor drive circuit that drives a three-phase half-wave drive sensorless motor in the embodiment of the present invention. In FIG. 1, 1 is a logical operation circuit, 2 is a trapezoidal wave generation circuit, 3 is a voltage / current conversion circuit,
4 is a current amplification circuit, 5 is a frequency / voltage conversion circuit, 6,
7, 8 are armature windings of sensorless motors, 9, 10, 1
Reference numeral 1 is an output transistor, 12, 23, 24 and 25 are comparators, 14 is a speed command input terminal, and 15 is a power supply voltage terminal. This part is the same as the conventional sensorless motor drive circuit. Reference numerals 16, 17, and 18 are comparators, 19 is a reference voltage, and 20, 21 and 22 are transistors for removing unnecessary current. This portion is a portion added to the conventional example.

Here, the three output transistors 9 and 1
0 and 11 have collectors connected to the other ends of the three-phase armature windings 6, 7, and 8 of the sensorless motor, one ends of which are commonly connected to the power supply voltage terminal 15, and the emitters thereof are grounded. Further, the comparators 23, 24 and 25 respectively constitute an induced voltage / power supply voltage comparing means, and each of the three-phase armature windings 6 and 6.
The induced voltages generated at 7 and 8 are compared with the power supply voltage V _CC . The logical operation circuit 1 includes comparators 23, 24, 25.
Output signals A _U , A _V , A _W are logically operated to determine energization timing for trapezoidal wave conversion B _U , B _V , B _W
The trapezoidal wave generation circuit 2 outputs the output signals B _U , B _V , and B _W of the logical operation circuit 1 to the trapezoidal wave voltage C _V ,
It has a function of converting into C _U and C _W , and in the logical operation circuit 1 and the trapezoidal wave generation circuit 2, three comparators 23, 24 and 25 are provided.
Output signals A _U , A _V , and A _W of n-phase trapezoidal wave voltage C _V ,
It functions as a trapezoidal wave converting means for converting into C _U and C _W.
The frequency / voltage conversion circuit 5 serves as frequency / voltage conversion means for generating a speed corresponding voltage Va proportional to the rotation speed of the sensorless motor. The comparator 12 detects an error voltage between the speed command voltage input from the outside and the speed corresponding voltage Va and outputs an error current I ₁ according to the error voltage.
It becomes a speed-compatible voltage comparison means. Voltage / current conversion circuit 3
Is a three-phase trapezoidal wave current D _U , D _V , D _{W having} a magnitude corresponding to the error current I ₁ of the three-phase trapezoidal wave voltage C _U , C _V , C _W output from the trapezoidal wave generation circuit 2. And is supplied to the bases of the three output transistors 9, 10, 11 via the current amplifier circuit 4, respectively.

The comparator 16, 17 and 18 compares the induced voltage E _U generated in the armature windings 6, 7, 8 of the 3-phase sensorless motor, E _V, E _W and predetermined the reference voltage 19, respectively It becomes the three induced voltage / reference voltage comparison means. Transistors 20, 21, 22 include three comparators 16, 1
Output signal S _U of 7, 18, S _V, the induced voltage E _U generated in the armature windings 6, 7, 8 of the 3-phase sensorless motor based respectively S _W, E _V, E _W is a predetermined reference voltage It serves as an unnecessary current removing means for interrupting the currents supplied from the voltage / current conversion circuit 3 to the bases of the three output transistors 9, 10, 11 in a period higher than 19.

FIG. 7 is a circuit diagram showing a specific configuration of the connection portion between the U-phase only current amplifier circuit 4 and the comparator 16.
In FIG. 7, 47 and 48 are transistors forming a current mirror, and 49 is a transistor driven by the transistor 48. Here, for example, the voltage / current conversion circuit 3 is configured as shown in FIG.

FIG. 8 is a signal waveform diagram at each point of FIG. 1, showing three-phase armature windings 6, 7, 8 of the sensorless motor.
And the induced voltage E _U, E _V, E _W generated in the trapezoidal wave current D _U of the voltage / current conversion circuit 3, D _V, and D _W, comparator 1
Output signal S _U of 6,17,18, S _V, S _W and a trapezoidal wave current P _U that is input to the current amplifier 4, P _V, shows and P _W.

Sensorless motor configured as described above
The operation of the drive circuit will be described below. Conventional
The circuit operation of the same part of the
As explained in the technical section of the above, duplicate explanation
Is omitted. When the sensorless motor starts, the armature winding
Induced voltage E on lines 6, 7 and 8_U, E_V, E_WOccurs.
The induced voltage E_U, E_V, E_WTo a certain reference voltage (eg
Power supply voltage V_CC) And comparators 16, 17, and 18
By comparing, the output signal S of FIG._U, S_V, S_WBut
Generated. This signal S_U, S_V, S_WExample using
For example, as shown in FIG. 7, the connection between the current amplification circuit 4 and the comparator 16 is
When the sequel is constructed, the signal S_UHigh level, low level
The transistor 20 is switched according to
Trapezoidal current D while the transistor 20 is on_UIs Transis
The current is amplified by flowing through the controller 20 to the ground.
The supply to the circuit 4 is cut off and the transistor 20 is turned off.
The period is the same as the conventional example, trapezoidal wave current D_UIs the current amplification circuit 4
Is amplified by and is supplied to the base of the output transistor 9.
Will be. As a result, as shown in FIG.
D_U, D _V, D_WIs an unnecessary minute current I_U, I_V, I_W
Is removed, trapezoidal current P_U, P_V, P_WBecome
It is supplied to the current amplification circuit 4. However, FIG.
Then unnecessary minute current I_U, I_V, I_WIn case of
Trapezoidal wave D_U, D_V, D_WIs shown. In addition,
By changing the quasi-voltage 19, the signal S_U,
S_V, S_WCan change the high level period of
It is possible, and by this, unnecessary minute current I_U, I_V, I_WTo
You can set the removal period freely.

In the above embodiment, the sensorless motor drive circuit for driving the sensorless motor of the three-phase half-wave drive has been described, but the present invention is not limited to this and is also applied to the drive of a sensorless motor of two-phase or four-phase or more. It goes without saying that you can do it. Further, in the above embodiment, the trapezoidal wave current is passed through the sensorless motor, but the current value gradually increases at the beginning of the energization period to each armature winding, and the current value gradually increases at the end of the energization period. Needless to say, the problem can be solved by applying the present invention to such a current waveform even when a current having a waveform that decreases to The trapezoidal wave in the present invention includes not only the original trapezoidal wave but also a waveform similar to the trapezoidal wave.

[0048]

According to the present invention, the sensorless motor is sequentially energized to rotate the sensorless motor, and the induced voltage generated in the armature winding of the sensorless motor is compared with the reference voltage. By shutting off the current supply to the output transistor during the period when the voltage is higher than the voltage, an attempt is made to flow to the armature winding of each phase while the armature winding of each phase of the sensorless motor is not energized. Unnecessary current can be removed, and acoustic power and spike noise of the motor can be reduced and low power consumption can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a sensorless motor drive circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional sensorless motor drive circuit.

FIG. 3 is a signal waveform diagram of each point in the sensorless motor drive circuit of FIG.

FIG. 4 is a circuit diagram showing a configuration of an example of a U-phase trapezoidal wave generation circuit in the sensorless motor drive circuit of FIGS. 1 and 2.

5 is a circuit diagram showing a configuration of an example of a voltage / current conversion circuit in the sensorless motor drive circuit of FIGS. 1 and 2. FIG.

6 is a signal waveform diagram in the voltage / current conversion circuit of FIG.

7 is a circuit diagram showing a configuration of a connecting portion between a U-phase comparator and a current amplifier circuit in the sensorless motor drive circuit of FIG.

8 is a signal waveform diagram of each point in the sensorless motor drive circuit of FIG.

9 is an output signal waveform diagram when resistors are inserted between the bases and emitters of the transistors 34, 36, and 38 in the voltage / current conversion circuit of FIG.

10 is a circuit diagram showing a configuration of a frequency / voltage conversion circuit in the sensorless motor drive circuit of FIGS. 1 and 2. FIG.

11 is a characteristic diagram showing the relationship between the induced voltage and the point a voltage of the frequency / voltage conversion circuit of FIG.

[Explanation of symbols]

1 logical operation circuit (trapezoidal wave conversion means) 2 trapezoidal wave generation circuit (trapezoidal wave conversion means) 3 voltage / current conversion circuit (voltage / current conversion means) 4 current amplification circuit 5 frequency / voltage conversion circuit (frequency / voltage conversion means) ) 6,7,8 armature winding 9,10,11 output transistor 12 comparator (speed command voltage / speed corresponding voltage comparison means) 14 speed command input terminal 15 power supply voltage terminal 16,17,18 comparator (induced voltage / Reference voltage comparing means) 19 Reference voltage 20,21,22 Transistor (unnecessary current removing means) 23,24,25 Comparator (induced voltage / power supply voltage comparing means) 26-29 Transistor 30,31 Constant current source 32 Reference voltage 33 condenser 34-44 transistor 45 constant current source 47-54 transistor 55 constant current source 56-59 resistance

Claims (1)

[Claims] 1. A sensorless motor drive circuit for driving an n-phase (n is an integer of 2 or more) sensorless motor in an n-phase half-wave, wherein one end of the sensorless motor is commonly connected to a power supply voltage terminal. N output transistors whose collectors are respectively connected to the other ends of the armature windings and whose emitters are grounded, and n induction transistors which compare the induced voltage generated in the n-phase armature windings with the power supply voltage. Voltage / power supply voltage comparison means, and trapezoidal wave conversion means for converting the output signals of the n induced voltage / power supply voltage comparison means into n-phase trapezoidal wave voltage,
Frequency / voltage conversion means for generating a speed-corresponding voltage proportional to the rotation speed of the sensorless motor, and speed command voltage / speed-corresponding voltage comparison for detecting an error voltage between a speed command voltage input from the outside and the speed-corresponding voltage. Means for converting the n-phase trapezoidal wave voltage output from the trapezoidal wave generating means into an n-phase trapezoidal wave current having a magnitude corresponding to the error voltage and supplying the trapezoidal wave current to the bases of the n output transistors. Voltage / current conversion means, and n induced voltage / reference voltage comparison means for respectively comparing the induced voltage generated in the n-phase armature winding of the sensorless motor with a predetermined reference voltage,
The voltage / current converting means outputs the induced voltage generated in the n-phase armature winding of the sensorless motor based on the outputs of the n induced voltage / reference voltage comparing means from the voltage / current converting means during a period in which the induced voltage is higher than the predetermined reference voltage. A sensorless motor drive circuit comprising: n unnecessary current removing means for interrupting a current supplied to the bases of n output transistors.