JPH09182486A - Motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect BFG with high accuracy by making the current application width of the current flowing in the specified stator winding smaller than that of the current flowing in the stator winding other than the specified stator winding. SOLUTION: A revolution detecting means 1 receives the input of the counter electromotive force e1, e2, and e3 induced in the stator windings of three phases. The revolution detecting means 1 detects the zero cross point of the counter electromotive force 31 and outputs it as a revolution signal (BFG). Moreover the revolution detecting means 1 detects the zero cross points of the counter electromotive force e1, e2 and e3 of three phases and converts it into a pulse n. This pulse n shows the zero cross point of the counter electromotive force e1, e2, and e3 of three phases, and is inputted into the logical pulse generating means 2 of a position signal generating means 10 and an inclination wave generating means 3. Accordingly, highly accurate BFG can be made detected, so highly accurate control can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device used in a magnetic recording / reproducing device (VTR) or the like.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting the rotation speed of a motor, a signal obtained by pulse-shaping a counter electromotive force induced in a stator winding of a motor without connecting a frequency generator (hereinafter referred to as "BFG"). Method) is known (for example, “Brushless DC motor drive method in which position detecting element is omitted”) National Technical Report p614 Vol.33 No.5 Oc
t.1987). If speed control is performed by using the frequency or the repetition period of this BFG as the rotation speed information of the motor, for example, as shown in Japanese Patent Publication No. 57-18434,
The speed of the motor can be stably controlled with a simple configuration.

A so-called full-wave drive type brushless DC motor, which supplies current to the stator windings in both directions, is
For example, it is shown in Japanese Patent Publication No. 62-260586. In this full-wave drive type brushless DC motor, by making the drive current flowing through the stator windings a trapezoidal wave with a conduction width of 180 degrees (electrical angle), vibration and noise can be extremely reduced during motor rotation. it can.

[0004]

However, the energization width is 180
When the frequency is set to 0, the detection accuracy of the zero-cross point detection of the back electromotive force decreases due to the influence of the voltage drop generated by the current supplied to the stator winding, and the detection accuracy of the BFG deteriorates. Therefore, when the control is performed using the BFG as the rotation speed information, there is a problem that the control performance deteriorates.

In view of the above problems, the present invention provides a vibration caused by rotation during driving of a full-wave drive type brushless DC motor,
It is an object of the present invention to realize a motor drive device that detects BFG with extremely low noise and high accuracy.

[0006]

In order to solve the above-mentioned problems, the motor drive device of the present invention detects the zero-cross points of the back electromotive force generated in each of the stator windings of a plurality of phases and sequentially performs pulse shaping. Rotation speed detection means for generating a pulse signal train and detecting a zero-cross point of the back electromotive force of only a predetermined one-phase stator winding among a plurality of phases to perform pulse shaping and output as BFG, and rotation speed detection means. Of the trapezoidal wave corresponding to the predetermined one-phase stator winding is narrower than the width of the tail of the trapezoidal wave corresponding to other than the stator winding. Position signal generating means for generating a rotor position signal, and power supply means for supplying electric power to the stator windings in accordance with the rotor position signal, of the current flowing through the predetermined stator windings. Fix the energizing width to other than the specified stator winding It is obtained by constituting less than conducting width of the current flowing in the windings.

According to the present invention, the back electromotive force induced in the stator winding of one phase among a plurality of phases is provided in the full-wave drive type brushless DC motor having the stator windings of a plurality of phases. The zero-cross point of can be detected with extremely high accuracy. Therefore, by waveform-shaping the back electromotive force induced in this one-phase stator winding into a BFG, it is possible to detect the BFG with high precision, and it is possible to perform control with extremely high precision. The current supplied to the stator windings of the remaining phases is a trapezoidal wave with a conduction width of 180 degrees, so there is very little vibration and noise during rotation.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a motor drive device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a motor drive device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a rotational speed detecting means, which is a three-phase stator winding 1
Back electromotive force e1, e2, e3 induced in 1, 12, 13
Is entered. The rotation speed detection means 1 detects the zero-cross point of the counter electromotive force e1 and outputs it as a rotation speed signal (BFG). Further, the rotation speed detecting means 1 uses the three-phase counter electromotive force e.
The zero-cross points of 1, e2, and e3 are detected and converted into pulse n. This pulse n is a three-phase counter electromotive force e1, e2,
It indicates the zero-cross point of e3 and is input to the logic pulse generating means 2 and the gradient waveform generating means 3 of the position signal generating means 10. The logic pulse generation means 2 responds to the pulse n output from the rotation speed detection means 1 to generate stator windings 11, 12, 1
It outputs 6-phase pulse signals p1 to p6 having the same frequency as the back electromotive force induced in No. 3. The ramp waveform generating means 3 generates a ramp wave output signal st in accordance with the input pulse n.

The 6-phase pulse signals p1 to p6 generated by the logic pulse generating means 2 are inputted to the trapezoidal wave signal synthesizing means 4, and here, the 6-phase pulse signals p1 to p6 and the gradient waveform generating means 3 are inputted. Based on the output signal st generated by
Six-phase trapezoidal wave signals d1 'to d6' are synthesized. 6-phase trapezoidal wave signals d1 'synthesized by the trapezoidal wave signal synthesis means 4 to
d6 'is input to the position signal creating means 5 and the rotor 20
Are converted into rotor position signals d1 to d6. The rotor position signals d1 to d6 are input to the power supply means 6.
The power supply means 6 sequentially supplies a drive current to the stator windings 11, 12 and 13 in both directions according to the rotor position signals d1 to d6. Thus, the position signal generating means 10 described above is used.
Is composed of a logic pulse generating means 2, a gradient waveform generating means 3, a trapezoidal wave signal synthesizing means 4 and a position signal generating means 5.

As described above, in the motor drive device according to the present invention, the rotation speed detecting means 1, the logic pulse generating means 2, the slope waveform generating means 3, the trapezoidal wave signal synthesizing means 4, the position signal generating means 5, and the power supply means. It is composed of 6.

Further, in the embodiment shown in FIG. 1, the motor includes stator windings 11, 12, 13 and a rotor 20.

The operation of the motor drive device constructed as above will be described in detail. First, the operation of the power supply means 6 will be described in order to explain each signal necessary for driving the motor in the motor drive device of the present invention.

FIG. 2 is a circuit diagram showing an example of the power supply means 6 which constitutes the motor drive device of the present invention. This figure 2
In FIG. 1, 20 is a rotor and 11, 12, and 13 are stator windings, which are the same as those shown in FIG. 21,
Driving transistors 22, 23, 24, 25 and 26 supply current to the stator windings 11, 12 and 13 by turning these transistors on and off. Of these transistors, 21, 22, 23 are PNP transistors, and 24, 25, 26 are NPN transistors. 27 is a power supply.

FIG. 3 is a signal waveform diagram of each part of the power supply means 6 shown in FIG. In FIG. 3, e1, e
2, e3 are the stator windings 11 and 1 respectively as described above.
2 is a back electromotive force waveform induced in 2 and 13. d1, d
Reference numerals 2, d3, d4, d5, and d6 are 6-phase signals created by the position-signal creating means 5 as described above, and correspond to 6-phase position signals obtained according to the rotational position of the rotor 20.

The six-phase position signals d1 to d6 are input to the bases of the driving transistors 21, 26, 22, 24, 23 and 25, respectively. However, the direction of the signal applied to the base of each transistor is the PNP transistor 2
The current flows in the directions of 1, 22, and 23, and the current flows in the NPN transistors 24, 25, and 26. Each transistor amplifies the applied base current, and a current proportional to each base current flows to each collector. As a result, the stator windings 11, 12, and 13 are energized with the currents i1, i2, and i3 in both directions. The phase switching operation is sequentially performed to rotate the rotor 20.

Incidentally, D shown in the diagram of i1 in FIG.
Reference character c indicates a conduction width of the drive current supplied to the stator winding 11, and the conduction width is smaller than 180 degrees. That is, the drive current flowing through the stator winding 11 has a period during which the current becomes zero, and this period is just near the zero cross point of the back electromotive force waveform induced in the stator winding 11. This energization width Dc can be freely set by changing the DC value of the reference voltage source 122 of the position signal generating means 5 of FIG. 12 described later. Further, with the drive currents i2 and i3 flowing through the stator windings 12 and 13,
The energization width is 180 degrees.

The operation of each unit that performs such signal processing will be described. FIG. 4 shows the rotation speed detecting means 1 shown in FIG.
FIG. 3 is a diagram showing an example of the circuit configuration of FIG. In FIG.
Reference numerals 14, 15, and 16 are resistors, one of which is connected to the stator windings 11, 12, and 13 and the other of which is commonly connected. Reference numerals 41, 42 and 43 are comparators, and their input terminals (+) are stator windings 11, 12 and 13 respectively.
The input terminal (-) is connected to the common connection point of the resistors 14, 15 and 16. Here, the output E1 of the comparator 41 is output to the outside as BFG. 44, 45,
An AND circuit 46 is connected to the outputs of the comparators 41 and 42, the comparators 42 and 43, and the comparators 43 and 41, respectively. 47 is an OR circuit, and AND circuits 44, 4
The respective outputs of 5 and 46 are input and the signal m is output. 48
Is an XOR circuit, and one input has an output m of the OR circuit 47.
Is input, and the output m of the OR circuit 47 is input to the other input,
A signal delayed by the time constant determined by the resistor 49 and the capacitor 50 is input. The output of the XOR circuit 48 is output to the outside as a signal n.

The operation of the rotation speed detecting means 1 shown in FIG. 4 will be described with reference to FIG. The resistors 14 and 1 shown in FIG.
Since 5 and 16 are respectively connected to the stator windings 11, 12 and 13, the common connection point of the resistors 14, 15 and 16 is the same as the neutral point o of the stator windings 11, 12 and 13. An electric potential is obtained. Therefore, it is not necessary to extract the neutral point of the stator winding from the motor. At the input terminals (+) of the comparators 41, 42, 43 shown in FIG. 4, the counter electromotive forces e1, e2, e induced in the stator windings 11, 12, 13 are generated.
3 are input respectively, and the input terminal (-) has a resistor 14,
Stator windings 11 and 1 obtained at common connection points 15 and 16
The neutral point potentials of 2 and 13 are input. Therefore, the output terminals of the comparators 41, 42 and 43 are connected to E1 and E of FIG.
As shown by 2 and E3, pulses in which the waveforms of the back electromotive forces e1, e2, and e3 are shaped can be obtained. Pulse E1, E2, E3
Pulse edges of the counter electromotive forces e1, e2, and e3, respectively. Therefore, the output of the OR circuit 47 has a pulse waveform shown by m in FIG. This is because the phase of the rising and falling edges of the pulse is
It is a pulse waveform that coincides with the zero-cross points of the three-phase back electromotive forces e1, e2, and e3. A pulse is output from the XOR circuit 48 at each zero-cross point of the three-phase back electromotive forces e1, e2, and e3, and six times per cycle of the back electromotive forces e1, e2, and e3 (every 60 degrees in electrical angle). Pulse n is output. This is a waveform obtained by differentiating the output pulse m of the OR circuit 47 from both edges.

Next, the logic pulse generating means 2 will be described in detail. FIG. 6 is a diagram showing an example of the circuit configuration of the logic pulse generating means 2 shown in FIG. 1, and FIG. 7 shows the signal waveform of each part thereof.

In FIG. 6, reference numeral 61 is a 6-phase ring counter, to which the pulse n output from the rotation speed detecting means 1 is input, and from six output terminals, p1, p2, and p1 shown in FIG.
The 6-phase pulse signals of p3, p4, p5, and p6 are output to the trapezoidal wave signal synthesizing unit 4. The pulse width of these pulse signals is 60 electrical degrees.

Next, the gradient waveform generating means 3 will be described in detail. FIG. 8 is a diagram showing an example of the circuit configuration of the gradient waveform generating means 3 shown in FIG. 1, and FIG. 9 shows the signal waveform of each part thereof.

In FIG. 8, reference numeral 81 is the rotational speed detecting means 1
Is a charging / discharging capacitor for generating a sawtooth wave according to the output pulse n of
Is a constant current source circuit for supplying a charging current to. 83
Is a reset switch for discharging the electric charge stored in the charging / discharging capacitor 81, and 84 is a buffer amplifier whose input terminal is connected to the charging / discharging capacitor 81. The output of the buffer amplifier 84 becomes the output st of the gradient waveform generating means 3.

The operation of the gradient waveform generating means 3 configured as described above will be described with reference to the signal waveform charts of the respective portions in FIG. The pulse n is the output of the rotation speed detection means 1,
The rising edges are three-phase stator windings 11, 12,
13 shows the zero-cross point of the counter electromotive force induced in 13, and the period of the pulse n corresponds to an electrical angle of 60 degrees. Here, FIG.
In the above, the pulse width of the pulse n is enlarged for convenience, but
In reality, it is sufficiently smaller than the pulse period. While the reset switch 83 is off, the constant current source circuit 8
The charging current is supplied from 2 and the charging / discharging capacitor 81
Is charged at a constant slope. However, since the reset switch 83 is momentarily turned on when the pulse n is input, the electric charge stored in the charging / discharging capacitor 81 is instantaneously discharged. This is shown in st of FIG. As described above, the ramp waveform generating means 3 generates the sawtooth ramp-shaped output signal st having the same phase as the pulse n.

Next, the trapezoidal wave signal synthesizing means 4 will be described in detail. FIG. 10 shows a trapezoidal wave signal combining means 4 shown in FIG.
12 is a diagram showing an example of a circuit configuration of FIG. 11, and FIG. 11 shows a signal waveform diagram of each part thereof.

In FIG. 10, reference numeral 101 denotes an input terminal of the trapezoidal wave signal synthesizing means 4, which is an output signal s of the ramp waveform generating means 3.
t is input. An inverting amplifier 102 receives the output signal st of the gradient waveform generating means 3 and outputs a signal sd obtained by inverting the output signal st. Reference numeral 103 is a buffer amplifier, which is connected to a reference voltage source 104 and outputs a signal sf. The output signal st of the ramp waveform generating means 3, the output signal sf of the buffer amplifier 103, and the output signal sd of the inverting amplifier 102 are signal combining means 111, 112, and 11, respectively.
3, 114, 115, 116. In addition,
Since these signal synthesizing means have the same configuration, only the configuration of the signal synthesizing means 111 is shown. In the signal synthesizing means 111, 117, 118 and 119 are switches, one of which is the input terminal 101 and the buffer amplifier 1 respectively.
03 and the inverting amplifier 102. These switches 117, 118, 119 are six-phase pulse signals p1, p2, p3, p output from the logic pulse generating means 2.
Three pulse signals (p1, p2, p4, p5, p6)
It is turned on / off according to the output of p3). Then, the signal synthesizer 111 outputs a signal indicated by d1 'in FIG. Similarly, the signal synthesizing means 112, 113, 1
14, 115, and 116, three pulse signals (p2, p3, p4), (p3, p4, p5), and (p
4, p5, p6), (p5, p6, p1), (p6, p
Three switches (not shown) are turned on / off in accordance with (1, p2), and signals indicated by d2 'to d6' in FIG. 11 are output.

The operation of the trapezoidal wave signal synthesizing means 4 configured as described above will be described in more detail with reference to FIG. In FIG. 11, as described above, n indicates the output pulse of the rotation speed detecting means 1. Also p1, p2, p
3, p4, p5, and p6 represent output pulse signals of the logic pulse generating means 2, and st represents output signals of the gradient waveform generating means 3. The inverting amplifier 102 receives the output signal st of the gradient waveform generating means 3 and receives the output signal st as shown by sd in FIG.
A signal obtained by inverting st is output. sf is the output signal of the buffer amplifier 103, and its magnitude is the slope waveform signal s
It is set equal to the peak value of t. Signal synthesizer 1
The switches 117, 118, and 119 constituting 11 are pulse signals p1 and p2 output from the logic pulse generating means 2.
Since the signal is turned on by the signal “H” and turned off by the signal “L” according to “H” and “L” of p3, the outputs of the input terminal 101, the buffer amplifier 103, and the inverting amplifier 102 are signal combining means. 11 are sequentially connected to the output terminals, and in FIG.
A trapezoidal wave signal indicated by 1'is obtained.

Next, the position signal generating means 5 will be described in detail. FIG. 12 is a diagram showing an example of the circuit configuration of the position signal generating means 5 shown in FIG. 1, and FIG. 13 is a signal waveform diagram of each part thereof.

In FIG. 12, reference numeral 121 is a subtractor, to which the trapezoidal wave signal d1 'synthesized by the trapezoidal wave signal synthesizing means 4 and a constant DC value of the reference voltage source 122 are inputted. 12
3, 124 and 125 are multipliers, the output of the subtractor 121 is input to the multiplier 123, and the multipliers 124 and 125
Is a trapezoidal wave signal d synthesized by the trapezoidal wave signal synthesis means 4.
3'and d5 'are input. Reference numeral 126 is an adder to which the outputs of the multipliers 123, 124 and 125 are input. 127 is an amplifier, and an adder 12 is provided at the input terminal (+).
The addition result of 6 is input, and the DC value of the reference voltage source 128 is input to the input terminal (-). The output of the amplifier 127 is input to the gain control inputs of the multipliers 123, 124 and 125, respectively, and controls the gain of each multiplier. Then, from the output terminals of the multipliers 123, 124, and 125,
The signals d1, d3, d5 shown in FIG. 13 are output. That is, the subtractor 121, the multipliers 123, 124 and 125, the adder 126, and the amplifier 127 constitute the upper position signal generating means 131 for generating the base signal applied to the upper transistors 21, 22, and 23 shown in FIG. doing. Similarly, the trapezoidal wave signal d synthesized by the trapezoidal wave signal synthesis means 4
2 ', d4', and d6 'are lower position signal generating means 132.
Are converted into signals d2, d4, and d6. here,
The lower position signal creating means 132 is the upper position signal creating means 1
Since it has the same configuration as 31, only the configuration of the upper position signal generating means 131 is shown in detail in FIG.

The operation of the position signal generating means 5 configured as described above will be described with reference to the signal waveform charts of the respective parts in FIG. In FIG. 13, d1 'to d6' are 6-phase trapezoidal wave output signals of the trapezoidal wave signal synthesizing means 4, and the width of the tail of the output waveform is 180 degrees (electrical angle) as shown in FIG. . The alternate long and short dash line in the figure indicates the reference voltage source 122.
The DC value of is shown. That is, from the subtractor 121, only the part of the signal d1 ′ shown in FIG. 13 above the dashed line is output. Multiplier 12
3, 124, 125, the adder 126, and the amplifier 127 form a closed loop, and the multiplier 123, so that the output of the adder 126 becomes equal to the DC value of the reference voltage source 128.
The gains of 124 and 125 are controlled. Therefore, each output of the multipliers 123, 124, 125 is
As shown in d1 to d6, a 6-phase trapezoidal wave having the same waveform height is obtained. Of the six-phase trapezoidal waves, two of the waveforms d1 and d4 have the width Dc ′ of the skirt of the waveform smaller than 180 degrees. The width Dc ′ of the bottom of the waveform is set to 1 by changing the magnitude of the DC value of the reference voltage source 121.
It can be freely set from 80 degrees to 120 degrees.
Therefore, the conduction width Dc of the current flowing through the stator winding 11
Can be freely set from 180 degrees to 120 degrees.

As described above, the position signal generating means 10 is constituted by the logic pulse generating means 2, the gradient waveform generating means 3, the trapezoidal wave signal synthesizing means 4 and the position signal generating means 5, whereby the stator winding Rotor position signals d1, d corresponding to 11
4 generates a trapezoidal wave-shaped rotor position signal whose width Dc 'is smaller than the width of the rotor position signals d2, d5, d3 and d6 corresponding to the stator windings 12 and 13. can do.

The signals d1 to d6 of FIG. 13 are supplied to the power supply means 6 of FIG. 1 as the rotor position signals of the rotor 20, as described above.

As described above, the rotational speed detecting means 1 has the counter electromotive force e1 induced in the stator windings 11, 12 and 13.
The zero crossing points of e2 and e3 are detected and the pulse output E1,
E2 and E3 are created and converted into pulse n. At the same time, the pulse E1 is output as BFG. The logic pulse generation means 2 receives the pulse n and receives the six-phase pulse signals p1 to p.
6 is generated. Further, the pulse n is also input to the gradient waveform generating means 3 and has a sawtooth-shaped gradient wave signal s having the same phase as the pulse n.
t is generated. Ramp wave signal st and 6-phase pulse signal p1
.About.p6 are inputted to the trapezoidal wave signal synthesizing means 4 and synthesized into 6-phase trapezoidal wave signals d1 'to d6' shown in FIG.
These 6-phase trapezoidal wave signals are input to the position signal generating means 5 and converted into trapezoidal wave rotor position signals d1 to d6 shown in FIG.

Here, the rotor position signals d1 and d4 corresponding to the stator winding 11 have a hem width Dc 'of 180 electrical degrees.
The trapezoidal wave is smaller than the degree. Then, the power supply means 6 sequentially supplies the stator windings 11, 12, and 13 with drive currents as shown by i1, i2, and i3 in FIG. 3 in both directions in accordance with these rotor position signals d1 to d6. As a result, the rotor 20 is rotated.

In order to accurately detect the zero-cross point of the back electromotive force, it is necessary to make the current zero near the zero-cross point. Therefore, in the rotation speed detecting means 1,
In order to detect the BFG with higher accuracy, it is better to select the energization width Dc shown in FIG. 3 to be smaller than 180 degrees. Also,
Considering noise and vibration when the motor rotates, it is desirable that the angle be as close to 180 degrees as possible. According to the motor drive device of this embodiment, the motor can be driven with the conduction width Dc of the current flowing through the stator winding 11 being smaller than the conduction width of the current flowing through the stator windings 12 and 13. The current can be reduced to zero near the zero cross point of the back electromotive force induced in the stator winding 11, and the BFG can be detected with high accuracy in the rotation speed detection means 1. Further, by changing the DC value of the reference voltage source 121 of the position signal generating means 5, the conduction width D of the current flowing through the stator winding 11 is changed.
Since c can be freely adjusted from 180 degrees to 120 degrees,
It is possible to achieve both low noise and low vibration during rotation.

The rotation speed detecting means 1 in this embodiment uses three commonly connected resistors for detecting the potential of the neutral point o of the stator winding, as shown in FIG. However, the signal line may be directly drawn from the neutral point o of the motor for use. Further, in this embodiment, a three-phase motor in which the stator windings are Y-connected has been taken as an example, but the number of phases may be any number, and the motor in which the stator windings are Δ-connected may be any number. It is also possible to apply to.

Further, in this embodiment, the position signal generating means 10 is constituted by the logic pulse generating means 2, the gradient waveform generating means 3, the trapezoidal wave signal synthesizing means 4 and the position signal generating means 5 to rotate the position signal. A trapezoidal wave is used as the child position signal to smoothly switch the phase of the current supplied to the stator winding, but other configurations may be used. For example, the rotor position signal may be a rectangular wave having a conduction width of 120 degrees, and a filter circuit including a capacitor may be connected to the conduction terminal to smooth the phase switching. At this time, the motor driving device of the present invention can be realized by changing the time constant of the filter circuit connected to the one-phase energizing terminal. When a filter circuit is connected to the energizing terminals to smooth the phase switching of the drive current, the motor may include a rotor position detecting element such as a hall element.

[0038]

As described above, according to the present invention, when the brushless DC motor of the full wave drive system is driven, the conduction width of the current supplied to the stator winding of one of the plural phases is 180. By setting the value smaller than 0 degree, the current can be reduced to zero near the zero cross point of the back electromotive force induced in the one-phase stator winding, so that the detection accuracy of the back electromotive force is improved and By detecting the generated counter electromotive force as a BFG (rotational speed signal), a highly accurate BFG can be obtained.
Can be obtained. Therefore, by using this BFG for controlling the rotation speed of the motor, highly accurate speed control can be performed without providing a special frequency generator for the motor. Further, in the drive current supplied to the stator winding other than the one-phase detecting BFG, the conduction width is 180
Because of the degree, vibration and noise can be extremely reduced when the motor rotates.

[Brief description of the drawings]

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

FIG. 2 is a circuit configuration diagram showing an example of a power supply means in the device.

FIG. 3 is a signal waveform diagram of each part of the power supply means in the device.

FIG. 4 is a circuit configuration diagram showing an example of a rotation speed detection unit in the same device.

FIG. 5 is a signal waveform diagram of each part of the rotation speed detection means in the same device.

FIG. 6 is a circuit configuration diagram showing an example of a logic pulse generating means in the device.

FIG. 7 is a signal waveform diagram of each part of the logic pulse generating means in the same device.

FIG. 8 is a circuit configuration diagram showing an example of a gradient waveform generating means in the same apparatus.

FIG. 9 is a signal waveform diagram of each part of the gradient waveform generating means in the same apparatus.

FIG. 10 is a circuit configuration diagram showing an example of trapezoidal wave signal combining means in the same apparatus.

FIG. 11 is a signal waveform diagram of each part of the trapezoidal wave signal combining means in the same apparatus.

FIG. 12 is a circuit configuration diagram showing an example of a position signal generating means in the device.

FIG. 13 is a signal waveform diagram of each part of the position signal generating means in the same device.

[Explanation of symbols]

 1 Rotational Speed Detection Means 6 Power Supply Means 10 Position Signal Generating Means 11 Stator Windings 12 Stator Windings 13 Stator Windings

Claims (3)

[Claims] Claim: What is claimed is: 1. A back electromotive force generated in each of a plurality of stator windings is detected and sequentially pulse-shaped to output a pulse signal train, and a predetermined stator among the plurality of stator windings. Rotation speed detecting means for pulse-shaping the counter electromotive force generated in the winding and outputting it as a rotation speed signal, and a trapezoid corresponding to the predetermined stator winding in response to the pulse signal train of the rotation speed detecting means. Position signal generating means for generating a trapezoidal-wave-shaped rotor position signal having a skirt width of the trapezoidal wave whose width is narrower than the width of the skirt of the trapezoidal wave corresponding to a position other than the predetermined stator winding, and according to the rotor position signal. Power supply means for supplying electric power to the stator winding, the width of the current flowing in the predetermined stator winding, the width of the current flowing in the stator windings other than the predetermined stator winding. A motor characterized by being configured smaller than the energization width Operated device. 2. The position signal generating means includes logic pulse generating means for generating pulse signals of a plurality of phases in response to the pulse signal train of the rotation speed detecting means, and a ramp waveform according to the pulse signal train of the rotating speed detecting means. And a trapezoidal wave signal synthesizing means for synthesizing a trapezoidal wave signal from the pulse signals of a plurality of phases output from the logic pulse generating means and the sloped waveform output from the slope waveform generating means, Position signal generating means for generating a rotor position signal by subtracting a constant DC value from a trapezoidal wave signal corresponding to the back electromotive force generated in the predetermined stator winding in the trapezoidal wave signal. A motor drive device characterized by the above. 3. The position signal creating means includes subtracting means for subtracting a constant DC value from a trapezoidal wave signal corresponding to a back electromotive force generated in a predetermined stator winding among a plurality of input trapezoidal wave signals. A plurality of multiplying means for respectively converting the output of the subtracting means and the trapezoidal wave signal not input to the subtracting means into rotor position signals; an adding means for adding respective outputs of the multiplying means; An amplifying means for controlling the output of the multiplying means so that the output of the means has a predetermined value, and changing the direct current value to be subtracted by the subtracting means, so that the current flowing through the predetermined stator winding. The motor drive device according to claim 2, wherein the energization width of the motor drive device is configured to be freely set.