JPH0763230B2 - DC non-commutator motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relatively small capacity commutatorless motor used under a direct current power source, and is used as a recording / reproducing device such as a video tape recorder or an air cooling fan motor. The present invention provides a suitable DC non-commutator motor.

[0002]

2. Description of the Related Art In recent years, DC non-commutator motors have been widely used in many audio equipments, video tape recorders, and even floppy disk drive devices. From their convenience to air cooling fan motors. DC non-commutator motor is used.

Conventionally, a two-phase or three-phase half-wave drive system or full-wave drive system has predominantly been used as a DC non-commutator motor of this type. Each drive method has advantages and disadvantages. For example, the three-phase drive method requires a smaller number of drive power elements than the two-phase drive method, but has a larger number of position detection elements for detecting the rotational position of the rotor. Will be needed. By the way, if it is operated under a single power supply, the two-phase full-wave drive method requires eight power transistors and two Hall elements, and the three-phase full-wave drive method has six power transistors. And three Hall elements are required.

Many attempts have conventionally been made to reduce the number of position detecting elements in the three-phase drive system.
A typical technique is disclosed in US Pat. No. 3,577,053 (hereinafter referred to as Document 1).

In the above-mentioned document 1, in a three-phase half-wave drive type non-commutator motor, an identification band having first, second, and third components having different light reflectances is provided on a rotor, By irradiating the identification band with a light beam and detecting the reflected light with a light receiving element, the change in the rotational position of the rotor is recognized as a three-step change in the output level of the light receiving element, and the phase winding depending on the level is energized. A device configured to do so is shown.

In addition, when the rotor is activated, the light beam happens to be the first ray.
When the boundary between the third constituent element and the third constituent element is irradiated, the output level of the light receiving element takes an intermediate value, so the detection circuit operates as if the second constituent element was detected. However, this causes reverse torque and vibration of the rotor,
It is described that in order to prevent this, the Schmitt circuit may constitute the output level discrimination circuit section of the light receiving element.

The same thing is disclosed in Japanese Patent Application Publication No. 46317 of 1982 (hereinafter referred to as Document 2). In Document 2, instead of the Schmitt circuit, a third structure of an identification band is disclosed. A drive circuit device is shown that is provided with a memory circuit for storing the detection of the portion of the element.

In each of Documents 1 and 2 described above, only one position detecting element and an identification band for position detection are used.
Although half-wave driving is possible, a method has also been proposed and put into practical use in which the energization state of the phase winding is sequentially switched without using any special position detection element (for example, Sony Corporation). CX2, a 3-phase commutatorless motor driving IC
0114).

[0009] In the patent application publication No. 39553 of 1981 (hereinafter referred to as reference 3), first, the energization state of each phase winding is switched by an output signal of a self-propelled three-phase multivibrator to rotate. A drive circuit device configured to switch the energization state to each phase winding by using a power generation waveform that appears in an idle winding of a three-phase stator winding after the child starts rotating is shown. Has been done.

[0010]

However, in the devices shown in the above-mentioned documents 1, 2 and 3, since the logic circuit is used for processing the position detection signal, the current switching to each phase winding is rapidly performed. As a result, there is an inconvenience that each phase winding becomes a kind of "voice coil" to generate noise, or electrical noise due to surge pulse or burst of semiconductor occurs.

In order to gently switch the current to each phase winding, it is necessary to make the input current waveform of the output transistor forming the drive circuit trapezoidal or sinusoidal. If the current amplification factor of 1 is different, the waveforms of the currents supplied to the phase windings are not the same, and the trapezoidal wave is close to a rectangular wave, or conversely is close to a triangular wave.

In view of the above problems, the present invention realizes a DC non-commutator motor in which the current amplification factor of the output stage of the drive circuit can be arbitrarily set without being affected by the variation of the current amplification factor of the transistor itself. That is the purpose.

[0013]

A direct current non-commutator motor according to the present invention includes a plurality of stator windings, a rotor provided with a permanent magnet having a plurality of magnetic poles facing the stator windings, and Position detecting means for detecting a rotational position of the rotor and generating a plurality of position detecting signals having different phases, and a stator winding based on an output signal from the position detecting means having a control signal input terminal. A driving means for supplying a current having a magnitude depending on the control signal is provided, and an output transistor to which an output current is supplied to the stator winding, and a current mirror circuit together with the output transistor are formed. A mirror transistor for supplying a first (K> 1) current to the first resistor, a second resistor for supplying an energization command current to the stator winding, and a second resistor for connecting both ends of the first resistor. Voltage and both ends of the second resistor In which the output portion of the driving means by a control circuit which is both by comparing the voltage to control the input current of said output transistor so as to equilibrate configured.

[0014]

According to the present invention, the current amplification factor of the output stage can be arbitrarily set without being affected by the variation in the current amplification factor of the transistor itself.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a motor configured to carry out the present invention. The three-phase stator winding 1,
2, 3 are star-shaped connected to each other, and the stator windings 1 to 3 are connected.
A permanent magnet 4 mounted on a rotor (not shown) is arranged so as to face the.

The main portion of the permanent magnet 4 is occupied by a main pole magnetized with 8 poles, and the inner peripheral portion thereof has a first component portion magnetized with N poles (indicated by the N symbol in the drawing). , The second component part which is not magnetized (indicated by Z symbol in the figure) and the third component part which is magnetized by S pole (indicated by S symbol in the figure). Has circular annular identification bands 5 arranged alternately in the circumferential direction. In addition, a Hall IC prepared as a rotor rotational position detecting element facing the identification band 5 (an integrated circuit in which a Hall power generator and another circuit are housed on a chip, and is generally called a Hall IC or a Hall switch). 6) are arranged.

On the other hand, a zigzag-shaped power generation winding 7 having 24 power generation element portions diffracted in a mysterious direction is arranged facing the inner circumference side of the main pole of the permanent magnet 4, and the inner circumference of the main pole is arranged. A non-magnetized portion for generating an AC signal of 12 cycles per one rotation of the rotor in the power generation winding 7 (even if not magnetized, it is magnetized so that the magnetic flux density sharply decreases. , Or a dimple may be provided)
It is set up in several places. Furthermore, stator winding 1,
The second and third lead wires are respectively the first power supply terminal U and the second power supply terminal.
Is connected to the power supply terminal V and the third power supply terminal W, and the star-shaped midpoint is connected to the terminal X.

The Hall IC 6 is the positive side power supply terminal 6
a, a negative side power supply terminal 6b, and an output terminal 6c, and the lead wire of the generator winding 7 is the output terminals 7a and 7b.
It is connected to the.

FIG. 2 is a block diagram of a DC non-commutator motor according to an embodiment of the present invention. In FIG. 2, block 10 is an internal connection of the motor block shown in FIG. It was done. That is, in the motor block 10, the current limiting resistor 8 is connected between the midpoint terminal X and the positive side power supply terminal 6a of the Hall IC 6,
The negative side power supply terminal 6b of the Hall IC 6 and one output terminal 7b of the power generation winding 7 are commonly connected and connected to the ground terminal G, and the output terminal 6c of the Hall IC 6 is connected to the position detection terminal P and the power generation winding 7 The local output terminal 7a is connected to the rotation detection terminal F.

A position detection signal whose level changes in three steps depending on the rotational position of the motor is output to the position detection terminal P by a processing circuit which will be described later. The position detection signal is output from the distributor 100 by three lines. Signal lines 100n, 1
00s, 100z, and further subjected to conditioning processing by the sequential circuit 200, and the drive signal generating circuit 30
Sent to 0.

On the other hand, the signal appearing at the rotation detection terminal F and the ground terminal G is supplied to the slope generation circuit 500 after being amplified to a sufficient amplitude by the amplifier 400, and at the same time as the speed detection signal for the rotation servo of the motor. The signals supplied to the terminals and appearing on the signal lines 100n and 100s are extracted once by one rotation of the motor by the extraction circuit 600 and are also supplied to the B terminal as a position detection signal for rotation servo of the motor. .

In the present invention, the rotary servo system of the motor is not mentioned, but here, the A terminal and the B terminal are used.
It is assumed that the error voltage is fed back to the drive signal generating circuit 300 via the E terminal based on the speed information and the position information obtained from the terminal.

In the slope generation circuit 500, a sawtooth wave and a delay pulse synchronized with the output signal of the power generation winding 7 are generated and supplied to the drive signal generation circuit 300. In the drive signal generation circuit 300, a three-phase winding drive signal based on the rotational position detection signal supplied from the sequential circuit 200 and the sawtooth wave and the delay pulse supplied from the slope generation circuit 500. Are generated and sent to the drive circuit 700. In the drive circuit 700, the winding drive signal is current-amplified and then the U terminal, V terminal, W
The three-phase stator windings 1 to 3 are energized via the terminals.

The J terminal is a terminal to which a command signal for stopping and rotating the motor is supplied. This command signal is sent to the sequential circuit 20.
0 is supplied to the driving circuit 700, but in the embodiment, when the J terminal is at the “L” level (low potential), the energization to the stator winding is stopped and the “H” level (high potential). In this case, the stator winding is energized.

In the embodiment of FIG. 2, 3 of the Hall IC 6 is used.
The output signal of the value level is supplied to the three signal lines 100n, 100
Distributor 100 for distributing to s, 100z as a binary signal
Can be easily realized by two comparators having different threshold voltages, and the amplifier 400 is also an AC amplifier. Therefore, the description of the internal configuration is omitted here, and the circuit configuration of the other circuit blocks is realized. A simple operation will be described with an example.

First, FIG. 3 is a circuit connection diagram showing a concrete configuration example of the Hall IC 6, and a constant voltage circuit section 61 using a well-known bandgap reference voltage source and the like,
It is composed of a Hall power generator 62 formed on a silicon substrate and other signal processing circuit portions.

When the Hall power generator 62 of FIG. 3 is opposed to the N-pole magnetized portion of the identification band 5 shown in FIG. 1, the potential of one output terminal 62a of the Hall power generator 62 rises, The potential of the local output terminal 62b drops. Therefore, since the collector potential of the transistor 63 decreases and the collector potential of the transistor 64 increases, most of the current flowing into the constant current transistor 65 is the transistor 66.
It becomes the collector current of. In the circuit of FIG. 3, the resistor 6 connected to the emitter side of the constant current transistor 65
7, and the resistance ratio of the resistor 69 connected to the emitter side of the constant current transistor 68 is set to 3: 4,
Assuming that the collector current of the constant current transistor 65 is 4 · Io, the collector current of the constant current transistor 68 is almost 3
・ Io.

The resistance value of the resistor 71 connected to the emitter side of the power receiving transistor 70 and the resistance values of the resistors 74 and 75 connected to the emitter sides of the constant current transistors 72 and 73 are the same. Since the resistance value of the resistor 77 connected to the emitter side of the constant current transistor 76 is set to be three times the resistance value of the resistor 71, the constant current transistors 72 and 73 are set.
The maximum collector current of each is about 3 · Io, and the collector current of the constant current transistor 76 is about Io.
Becomes

Therefore, three quarters of the collector current of the transistor 66 is supplied from the constant current transistor 73, and only the remaining one quarter is supplied from the first collector 78a of the transistor 78b. At this time, the output terminal 6c
The load resistor 79 connected to
While the current of Io is supplied from the collector 78b,
Since the current Io is also supplied from the constant current transistor 76, when the resistance value of the resistor 79 is Ro, the output terminal 6
A potential of 2 · Ro appears in c.

On the contrary, the hall power generator 62 is S of the identification band 5.
When facing the pole-polarized portion, most of the current flowing into the constant current transistor 65 is the transistor 8.
The collector current becomes 0, and a current Io flows through the first collector 81a and the second collector 81b of the transistor 81, and the current of the second collector 81b is supplied to the current mirror circuit formed by the transistor 82 and the transistor 83. It Therefore, at this time, most or all of the collector current of the constant current transistor 76 flows into the collector of the transistor 83, and the potential of the output terminal 6c becomes zero.

On the other hand, when the Hall power generator 62 faces the non-magnetized portion of the identification band 5, the transistors 66 and 80 are provided.
Since the collector currents of the transistors are almost balanced, the transistor 6
All the collector currents of the constant current transistors 6 and 80 are supplied from the constant current transistors 72 and 73, the collector currents of the transistors 78 and 81 become zero, and only the collector current of the constant current transistor 76 is supplied to the load resistor 79 and the output terminal 6
The potential of c becomes Io · Ro.

In this manner, the output voltage of the Hall IC 6 changes in three steps depending on the position of the Hall power generator 62 facing the identification band 5.

FIG. 4 shows the relative positional relationship between the main magnetic pole and the identification band of the commutatorless motor constructed as shown in FIGS. 1 and 2 and the change in the position detection signal obtained from the Hall IC 6. When the relative rotation angle between the identification band 5 provided on the rotor and the Hall IC 6 arranged on the stator changes as shown by the mechanical angle or the electrical angle in FIG. The output voltage of Hall IC6 is shown in Fig. 4.
It changes like (a).

Next, FIG. 5 shows the sequential circuit 20 shown in FIG.
2 shows an example of a flow chart when 0 is realized by software such as a microcomputer. First, in the branch 201, whether the signal line 100n of FIG. Whether or not it is opposed to the magnetized portion is determined. If yes, the process is transferred to the processing block 202. If not, the Hall IC 6 in the branch 203 is opposed to the S pole magnetized portion of the identification band 5. If yes, the process moves to the process block 204, and if no, the process moves to the process block 205.

In the processing block 202, N of the three systems of signals supplied to the drive signal generating circuit 300 of FIG.
Only one corresponding to the pole part is activated,
This corresponds to activating only one of the three output ports in the microcomputer.
When the processing in the processing block 202 is completed, the processing proceeds to the branch 206, where it is determined whether or not the signal line 100s in FIG. 2 is in the active state similarly to the branch 203, and if yes, the processing is performed in the processing block 204. If no, the branch 206 determines again. In the processing block 204, only one of the signals of the three systems supplied to the drive signal generating circuit 300, which corresponds to the S pole portion, is activated, and when this processing ends, the branch 2
The processing moves to 07.

In the branch 207, it is determined whether or not the signal line 100z of FIG. 2 is in the active state. If yes, the process moves to the processing block 205, but if not, the determination by the branch 207 is executed again. . Processing block 20
At 5, in the signals of the three systems supplied to the drive signal generating circuit 300, only one corresponding to the non-magnetized portion is activated, and when this processing ends, the processing moves to the branch 208. In the branch 208, similarly to the branch 201, it is determined whether or not the signal line 100s in FIG. 2 is in the active state, and if yes, the process is transferred to the processing block 202. Run.

In this way, immediately after the start, the signal line 10 is connected by the branch 201 or the branch 203.
The output corresponding to the signal line in the active state of 0n, 100s, and 100z is supplied to the drive signal generation circuit 300, and thereafter, the processing block 202, the branch 206, the processing block 204, the branch 207, and the processing block 20.
5. Since it enters the loop constituted by the branch 208, the state of the output supplied to the drive signal generation circuit 300 changes only when the signal lines 100n, 100s, and 100z are activated in this order. .

That is, the sequential circuit shown in FIG. 5 is connected to each other in a ring shape to output three drive command signals to the drive signal generating circuit 300, that is, the processing blocks 202, 204 and 205. And the signal line 100
Of n, 100s, and 100z, a sequential circuit that changes the output state of the output section only when a pre-ordered signal line is activated, and is further configured by branches 201 and 203, When the rotor is started, the output state of the sequential circuit is changed to the signal line 10
It also has an initialization circuit that depends on the output state of the distributor 100 to 0n, 100s, and 100z.

FIG. 6 shows an example in which the sequential circuit 200 of FIG. 2 is configured by hardware, and its basic operation is the same as that of the flowchart of FIG.

In FIG. 6, NAND gates (positive logic NAND gates) 211 and 212 having respective first input terminals 211a and 212a and output terminals which are cross-coupled to each other, The first composed of a NAND gate 213 whose output terminal is connected to the second input terminal 211b of the NAND gate 211
NAND block 2 having the same configuration as the logic block 210 of FIG.
Second logical block 220 by 21, 222, 223
And NAND gates 231, 232, 233 having the same configuration
And the third logic block 230 according to
12b and the first input terminal 213 of the NAND gate 213.
The output of the NAND gate 232 is supplied to a
The NAND gate 2 is connected to the second input terminal 222b of the gate 222 and the first input terminal 223a of the NAND gate 223.
The output of the NAND gate 222 is supplied to the second input terminal 232b of the NAND gate 232 and the first input terminal 233a of the NAND gate 233 to form a sequential circuit.

The NAND gates 213, 223 and 2 are also provided.
The second input terminals 213b, 223b, 233b of 33 are the signal lines 100s, 100n, 100 of FIG. 2, respectively.
connected to input terminals s1, n1, z1 connected to z,
Output terminals s2, n2, and z2 for supplying a drive command signal to the drive signal generation circuit 300 of FIG.
It is connected to the output terminals of the gates 211, 222 and 231. In addition, NAND gates 212, 222, 232
The third input terminals 212c, 222c, 232c of the above are all initialization signal input terminals j1 connected to the J terminal of FIG.
It is connected to the.

Now, an outline of the operation of the sequential circuit shown in FIG. 6 will be described based on the output waveform of the position detection signal shown in FIG.

First, the signal waveform of FIG. 4A shows the output signal of the Hall IC 6 of FIG. 2 as already described, and the signal waveforms of FIGS. 4B, 4C, and 4D. Is a signal waveform appearing on each signal line after being distributed to the signal lines 100n, 100s, 100z by the distributor 100 based on the output signal of the Hall IC 6. In the following description of the operation of the logic circuit, it is assumed that positive logic is used and each signal line is in an active state when it is at a high potential. Further, a high potential state is represented by'H 'and a low voltage state is represented by'L'.

Now, when the rotation of the motor is stopped or immediately after the power is turned on, the initialization signal input terminal j1 shown in FIG.
Of the NAND gate 212,
Since the output levels of 222 and 232 are forcibly held at “H”, the levels of the output terminals n2, s2 and z2 become equal to the levels of n1, s1 and z1 at the input terminals.

Assuming now that the Hall IC 6 of FIG. 2 faces the position where the electrical angle of FIG. 4 is 0 °, the level of the output terminal z2 becomes "H", and the levels of the output terminals n2 and s2 become. Although it becomes "L", this state continues even after the level of the initialization signal input terminal j1 shifts to "H", the rotor of the motor starts to rotate, and the Hall IC 6 magnetizes the N pole of the identification band 5. When facing the opposite portion, the level of the input terminal z1 shifts to "L", and the level of the input terminal n1 shifts to "H" instead.

When the level of the input terminal n1 shifts to "H", since the output level of the NAND gate 212 has been "H" before that, the output level of the NAND gate 223 shifts to "L", and the NAND gate 221 and NAN
By inverting the output state of the gate pair by the D gate 222, the output level of the NAND gate 221 becomes “H” and the output level of the NAND gate 222 becomes “L”. When the output level of the NAND gate 222 shifts to “L”, the NAND gate 231 and the NAND gate 23
The output state of the gate pair by 2 is inverted, and as a result, the level of the output terminal n2 shifts to "H" and becomes the active state,
The level of the output terminal z2 shifts to "L" and the output terminal s2
And becomes inactive.

When the rotor further rotates and the Hall IC 6 approaches the position of electrical angle 180 ° in FIG. 4, FIG. 4 (d)
As shown in, the level of the input terminal z1 shifts to "H" again, but since the output level of the NAND gate 222 shifts to "L" at this time, the third logic block 2
No change occurs in 30, and the output states of the output terminals n2, s2 and z2 do not change.

Subsequently, when the level of the input terminal s1 shifts to "H", the output level of the NAND gate 232 shifts to "H" before that, so that the output level of the NAND gate 213 shifts to "L", NAND gate 211 and N
The output state of the gate pair by the AND gate 212 is inverted, the level of the output terminal s2 shifts to "H", and the level of the output terminal n2 shifts to "L". After all, the sequential circuit shown in FIG. 6 has a function of reflecting the input on the output only when the input terminals are activated as ordered.

In this way, the input terminals n1 and s of FIG.
When a position detection signal as shown in FIGS. 4B, 4C, and 4D is supplied to 1, z1, output terminals n2, s2, z
A drive command signal as shown in FIGS. 4 (e), (f), and (g) is output to 2.

As is clear from FIG. 4, it is possible to store other information in the identification band 5 by using the sequential circuit as shown in FIG. 5 or 6. For example, in the vicinity of the electrical angle of 540 ° of the identification band in FIG. 4, the pattern is magnetized in a pattern different from the other parts. However, while the motor rotor is rotating, this unique pattern affects the output state of the sequential circuit. Therefore, it can be positively used for other purposes as described later.

By the way, the signal waveform of FIG.
Comparing the signal waveforms in (f), it can be seen that they are exactly the same. This means that if the use of the sequential circuit is limited to the magnetized discrimination band as shown in FIG. 4, the detection signal supplied to the input terminal s1 of FIG. 6 is directly transmitted to the output terminal s2 as an output signal. This means that there is no problem.

FIG. 7 shows a sequential circuit simplified in consideration of these points. In FIG. 7, FIG.
Inverter 214 is used in place of NAND gate 213 of NAND gate 231 and NAND gate 23.
An inverter 234 is used in place of the gate pair formed by 2, but its operation is almost the same as that of the sequential circuit of FIG.

Next, FIG. 8 shows the slope generation circuit 500 of FIG.
2 shows an example of a specific circuit configuration of the amplifier 400. The output signal of the amplifier 400 of FIG.
The output is amplified by 01 until it becomes a square wave.
At the leading edge of the output signal of the amplifier 501, the first trigger pulse generating circuit composed of the NAND gates 502, 503 and 504 generates a trigger pulse, and at the trailing edge, the inverter 50 is generated.
5, the second trigger pulse generation circuit constituted by NAND gates 506, 507 and 508 generates a trigger pulse.

On the other hand, NAND gates 509 and 510, an inverter 511, transistors 512, 513 and 51.
4, 515, 516, 517, diode 518, resistors 519, 520, 521, 522, 523, 524, and capacitor 525 constitute a monostable multivibrator, and output signals of the first and second trigger pulse generation circuits. Is the trigger signal for this monostable multivibrator. The charge / discharge signal waveform of the capacitor 525 is supplied to the first output terminal g1, and the output signal of the monostable multivibrator is supplied to the second output terminal h1 via the inverter 526.

Therefore, when the signal waveform shown in FIG. 9D is supplied to the input terminal f1, the output terminals g1 and h
The signal waveforms appearing in FIG. 1 are as shown in FIGS. 9 (e) and 9 (f), respectively.

The signal waveforms in FIGS. 9A, 9B, and 9C show drive command signals supplied to the input terminals n3, s3, and z3 of the drive signal generation circuit 300 described below. Is.

Before the detailed description of the drive signal generating circuit 300 of FIG. 2, the operation of switching the energization state to the stator winding of the DC non-rectifier motor shown in FIGS. 1 and 2 will be described. To do.

As is clear from FIGS. 1 and 2, in the DC non-commutator motor described as the embodiment of the present invention, the rotor stationary position detecting means has an annular shape having three kinds of constituent elements. Since only the identification band 5 and the Hall IC 6 are provided, only three types of identification can be made according to the stationary position of the rotor. However, as is well known, in order to take the form of three-phase full-wave drive, six types of position detection information are required according to the stationary position of the rotor.

In the DC non-commutator motor shown in FIG.
Hall IC until the rotation speed of the motor increases to some extent
By supplying current to all three-phase stator windings 1, 2 and 3 based on the output signal of 6, the excess current is flowed to prevent the starting torque from decreasing and the motor rotation speed increases. After a sufficient signal is obtained from the generator winding 7, the generator winding 7
The drive signal generation circuit 30 outputs an energization switching signal for three-phase full-wave driving based on the output signal of the Hall IC 6 and the output signal of the Hall IC 6.
It is configured to produce inside 0.

The principle of switching the driving mode will be described with reference to FIG. FIG. 10A is a torque characteristic generated when a current is applied to each of the stator windings 1, 2 and 3 when the main magnetic pole of the permanent magnet 4 is sine-wave magnetized in the motor structure of FIG. The counterclockwise rotation torque is in the positive direction.

In FIG. 10A, the characteristic curve ua represents the torque generated when a current is passed through the stator winding 1 of FIG. 1 in the direction from the U terminal to the X terminal, and the characteristic curve ub
Represents the torque generated when a current is applied to the stator winding 1 in the direction from the X terminal to the U terminal. The characteristic curve va represents the torque generated when the stator winding 2 in FIG. 1 is energized in the direction from the V terminal to the X terminal, and the characteristic curve vb is in the stator winding 2 in the direction from the X terminal to the v terminal. It represents the torque generated when electricity is applied to the. Further, the characteristic curve wa represents the torque generated when the stator winding 3 of FIG. 1 is energized in the direction from the W terminal to the X terminal, and the characteristic curve wb represents the stator winding 3 in the direction from the X terminal to the W terminal. It represents the torque generated when electricity is applied to the.

On the other hand, FIG. 10 (c) shows the torque generated in the positive direction when current is applied to any two phases of the three-phase stator windings star-connected, as shown in FIG. 10 (a). It is shown by the generated torque ratio in the child winding. As is well known, the envelope of these curves in a three-phase full-wave drive motor is the actual output torque waveform.

That is, in FIG. 10C, the characteristic curve wv represents the torque generated when a current is passed from the W terminal to the V terminal in FIG. 1, and the characteristic curve uv is U.
The characteristic curve uw represents the torque generated when electricity is applied in the direction from the terminal to the V terminal, the characteristic curve uw represents the torque generated when electricity is applied in the direction from the W terminal to the W terminal, and the characteristic curve vw represents the characteristic curve vw. Represents the torque generated when electricity is applied in the direction, and the characteristic curve vu is from the V terminal to U
The torque generated when the current is applied in the terminal direction is shown, and the characteristic curve wu shows the torque generated when the current is applied from the W terminal to the U terminal.

If the maximum torque generated by each stator winding is set to 1, in the three-phase full-wave drive, energization switching to each stator winding is performed at every 60 ° electrical angle. The maximum torque Tma ₁ , the minimum torque Tmi ₁ , and the average torque Tav ₁ are given by (Equation ₁ ) (here, all the torques are made unitless and are simply expressed by exponents).

[0066]

[Equation 1]

[0067]

[Equation 2]

[0068]

[Equation 3]

FIG. 10D shows the Hall IC already described.
6 shows the output signal waveform of No. 6 and FIG. 10 (e) shows the output signal waveform of the amplifier circuit 501 used inside the slope generation circuit 500, but the rotor of the motor is stopped. In this state, only the output signal of the Hall IC 6 can be used as the position detection information. In order to start the motor using only three types of position detection information, it is conceivable to take the form of three-phase half-wave drive. In that case, the center point of the stator winding of the star connection shown in Fig. 2 is used. A power switching element for directly connecting the X terminal to the positive or negative power supply line is required.

In the embodiment of the present invention, such inconvenience is solved by the method described below. That is, the section in which the output signal is at a high potential is in the first energization section, the section in which the output signal is at a low potential is in the second energization section, and the intermediate potential is in correspondence with the three-level level change of the output signal of the Hall IC 6. The section is referred to as a third energization section, energization from the U terminal to the V terminal and the W terminal of FIG. 2 is performed in the first energization section, and the V terminal to the W terminal and the U terminal in the second energization section. To the U terminal and V terminal from the W terminal in the third energizing section.

At this time, the combined torque characteristics of the three-phase stator windings 1, 2, and 3 are as shown in FIG. 10B, and the characteristic curve uc represents the torque generated by the energization in the first section. The characteristic curve vc represents the torque generated by energization in the second section, and the characteristic curve w
c represents the torque generated by energization in the third section.

Therefore, the output torque of the motor when the energization is switched at the ideal timing is shown in FIG.
Considering that the current is equal to the envelope of the characteristic curve of (b) and the current equal to the sum of the currents of the other two-phase stator windings flows in the main winding of the three-phase stator windings. Maximum torque Tm
a _2, a minimum torque Tmi _2, when obtaining the average torque Tav ₂ is as follows.

[0073]

[Equation 4]

[0074]

[Equation 5]

[0075]

[Equation 6]

As is clear from a comparison between (Equation 3) and (Equation 6), the same average torque as in three-phase full-wave driving can be obtained at the time of startup, and an additional power switching element is added. It is also possible to save the starting current as compared with the case where three-phase half-wave driving is performed. By the way, in any of the driving methods, assuming that the resistance value per one phase of each stator winding is the same, the starting current in the three-phase half-wave drive is double that in the three-phase full-wave drive. With the driving method described, the starting current is only increased by about 33 percent.

In the drive signal generating circuit 300 shown in FIG. 2, the drive mode is switched by utilizing that the error voltage supplied from the servo system to the E terminal becomes maximum when the motor is started.

FIG. 11 is a circuit connection diagram showing a concrete configuration example of the drive signal generating circuit 300. The input terminal E is a terminal to which an error voltage is supplied from the outside, and is the same as the E terminal in FIG. Is. The input terminals f3, g2 and h2 are output terminals f2 and f2 of the slope generation circuit 500 shown in FIG.
The signal waveforms shown in FIGS. 9 (d), (e), and (f) are supplied to the input terminals n3, s3, z by being connected to g1 and h1.
The position detection signals shown in FIGS. 9A, 9B, and 9C are supplied to 3 respectively.

The outline of the operation will be described based on the signal waveform diagram of FIG. 9. When the motor is started, the maximum voltage is supplied to the E terminal, and the transistors 301, 302, 303,
The comparator constituted by 304 and the constant current transistor 305 operates to turn on the transistor 306. When the transistor 306 is on, the transistors 307, 308, 309, 310, 31
No power is supplied to the first current mirror circuit composed of 1, 312, 313, 314, and 315. Therefore, the second current mirror circuit composed of the transistors 316 and 317 is also cut off, and the transistor 318 is disconnected. , 319, 320, 321, 322, 32
The third current mirror circuit formed by 3,324, 325, and 326 is also cut off.

On the other hand, the resistance 3 is set by the transistor 306.
Since one end of 27 is connected to the positive side power supply line 300a, the transistors 328, 329, 330, 33 are connected.
1, 332, 333 are all in a power supply standby state, and transition to an on state by the flow of a base current.

Assuming that the level of the input terminal n3 is "H" and the levels of the input terminals s3 and z3 are "L".
The transistors 334, 335, 336 are turned on, and as a result, the transistors 328, 329, 332 are turned on, and current can be supplied from the output terminals up1, wn1, vn1.

Further, the level of the input terminal s3 is "H",
If the levels of the input terminals z3 and n3 are'L ', the transistors 337, 338 and 339 are turned on, and the current can be supplied from the output terminals vp1, wn1 and un1 and the level of the input terminal z3. Is "H" and the levels of the input terminals u3, v3 are "L", the transistors 340, 341, 342 are turned on, and the current can be supplied from the output terminals wp1, un1, vn1.

FIG. 12 is a circuit connection diagram showing a concrete configuration example of the drive circuit 700 in FIG.
v2, wn2, up2, vp2 and wp2 are respectively shown in FIG.
1 of the drive signal generating circuit 300 shown in FIG.
It is connected to vn1, wn1, up1, vp1, and wp1. Therefore, when the level of the initialization signal input terminal j2 connected to the J terminal of FIG.
When current is supplied from the two terminals, the vn2 terminal, and the wn2 terminal, the transistors 701, 702, and 703 are in a conductive state, and the output terminals U, V, and W are star-connected as shown in FIG. Assuming that 1, 2, 3 are connected, energization is performed from the U terminal to the V terminal and the W terminal.

Similarly, vp2 terminal, wn2 terminal, u
When current is supplied from the n2 terminal, the transistor 7
04, 705 and the transistor 703 become conductive,
When current is supplied from the V terminal to the W terminal and the U terminal and current is supplied from the wp2 terminal, the un2 terminal, and the vn2 terminal, the transistor 706 and the transistor 7 are connected.
02 and 705 are in a conductive state, and electricity is conducted from the W terminal to the U terminal and the V terminal.

In this way, the motor starts rotating, as is apparent from the output torque characteristic of FIG. 10B,
When the rotation speed of the motor increases to some extent and the potential of the E terminal in FIG. 11 decreases, the transistor 306 turns off, the transistor 343, the constant current transistor 344.
Together with this, the collector current of the transistor 345 that constitutes the differential amplifier circuit starts to flow between the collector and the emitter of the transistor 308.
All of the transistors 315 are activated, and the current is supplied to the transistor 316 included in the second current mirror circuit through the transistor 309. The output currents of the transistors 309 to 315 change depending on the potential of the error voltage supplied to the E terminal.

By the way, D flip-flops (delayed flip-flops) 346, 347, 348, 34
9-350,351, AND-OR gates (AND means AND of positive logic, OR means OR of positive logic) 352, 353, 354 in FIG. The position detection signals shown in a), (b), and (c) and the rotation detection signal shown in FIG. 9 (d) are supplied, and further, the signal shown in FIG. It is supplied as a clock signal of 346 to 351. Therefore, D flip-flop 3
The output terminals of 46, 348 and 350 are shown in FIG.
The signal waveforms shown in (h) and (i) appear, and the signal waveforms shown in FIGS. 9 (j), (k), and (l) appear at the output terminals of the D flip-flops 347, 349, and 351.

The output of the D flip-flop 346 is "H".
The transistor 356 is turned off during the period when it is at the level, and the transistor 357 is turned off during the period when the output of the D flip-flop 347 is at the “H” level. Similarly, D flip-flops 348, 349, 350, 35
The transistors 358, 359, 360 and 361 are turned off during the period when the output of 1 is at the'H 'level.

On the other hand, the signal waveform shown in FIG. 9 (e) is supplied to the slope current generating transistor 362 via the input terminal g2, and the constant current transistor 364 supplies a constant current to the emitter side resistor 363 of the transistor 362. Is supplied, and a current dependent on the output current of the transistor 309 flows into the transistor 317. Therefore, the collector current of the transistor 362 has a peak dependent on the collector current of the transistor 345 included in the differential amplifier circuit. It has a value and its slope is
It becomes a sawtooth wave equal to the slope of the signal waveform of (e).

The collector current of the transistor 362 is supplied to the third current mirror circuit constituted by the transistors 318 to 326, and the transistor 320 is also provided.
The same current through transistors 365, 366, 36
It is supplied to the fourth current mirror circuit constituted by 7,368,369,370,371,372.

The first current is set by setting the output current of the low current transistor 364 and the resistance value of the resistor 363 to appropriate values, or by adjusting the resistance value of the emitter side resistor of each current mirror circuit. The maximum output current of the transistors 310 to 315 forming the mirror circuit,
321 to constitute the current mirror circuit of
The maximum output current of 326 and the maximum output current of the transistors 367 to 372 that form the fourth current mirror circuit can be made equal to each other, and the magnitudes of these maximum output currents are all errors supplied to the E terminal. It depends on the voltage.

Now, when both the output of the D flip-flop 350 and the output of the D flip-flop 351 are at the "H" level, that is, in the section P1 of FIG.
Since the output of the gate 373 becomes the “H” level, the transistor 374 is turned off, and the sawtooth current is supplied to the output terminal wn1 via the transistor 322.

Then, when the output level of the D flip-flop 346 becomes "H", the transistor 356 is turned off, so that current is supplied to the output terminal through the transistor 311 but the output of the D flip-flop 346 is output. And the outputs of D flip-flop 347 are both "H".
When it becomes the level, that is, in the section P2 of FIG. 9, the output of the AND gate 375 becomes the “H” level, the transistor 376 is turned on, and the sawtooth current flows in the collector of the transistor 368.

Therefore, the current supplied to the output terminal wn1 gradually decreases, and eventually the waveform of the current supplied to the output terminal wn1 becomes as shown in FIG. 9 (m).

Regarding the waveforms of the currents supplied to the other output terminals, the AND gates 373 and 375 and the other AND gate 3 are also provided.
77, 378, 379, 380 perform the same operation, and as a result, output terminals un1, vn1, v
The current waveforms supplied to p1, wp1, and up1 are shown in FIG.
(N), (o), (p), (q), (r).

The waveforms shown by broken lines in FIGS. 9 (m) to 9 (r) are current waveforms when the rotation speed of the motor increases and the potential of the E terminal decreases.

The six kinds of current signals produced in the drive signal generating circuit of FIG. 11 in this way are supplied to the drive circuit of FIG.
The stator windings 1, 2 and 3 are energized via 1 to 706.

By the way, assuming that the transistor 701 of FIG. 12 is formed as an assembly of a large number of small signal transistors on the IC substrate, and the transistor 707 is assigned to one of them, the transistor 701 and the transistor 707 are current mirror circuits. And a current of 1 / K of the collector current of the transistor 701 becomes the collector current of the transistor 707. Since the resistance value of the resistor 708 is zero, the value of K becomes equal to the emitter area ratio of the transistor 701 and the transistor 707.
Although the value of K increases as the resistance value of the transistor increases, the value thereof is affected by the collector current of the transistor 707.

That is, the emitter junction area of the transistor 701 is Sx, the emitter junction area Ix, the transistor 7
When the emitter junction area of 07 is Sy, the emitter current is Iy, the resistance value of the resistor 708 is Re, the electron charge is q, the Boltzmann constant is k, and the absolute temperature of the junction is T,
The relational expression of (Equation 7) holds.

[0099]

[Equation 7]

The collector current of the transistor 707 is supplied to the resistor 709, and the transistors 722, 731, 73
The control circuit constituted by 2, 733 and 734 compares the voltage across the resistor 709 with the voltage across the resistor 710, and balances them by the transistor 701.
Input current is controlled.

Therefore, when the input current is I ₁ , the collector current of the transistor 701 is I ₂ , the resistance value of the resistor 710 is R ₁ , and the resistance value of the resistor 709 is R ₂ , the current amplification factor GI in this portion is Given by (Equation 8).

[0102]

[Equation 8]

In the above description, the current amplification factor of the power supply block having the transistor 701 as an output section is substantially constant (in other words, it is not affected by the variation in the DC current amplification factor of each transistor). The other five power supply blocks operate in the same manner because they are configured based on the same operation principle.

Since the level of the initialization signal input terminal j2 in FIG. 12 is "L" immediately before the motor is stopped or started, the transistor 711 is in the ON state, and the transistors 712, 713, 714 are in the ON state. , 715, 716
The current mirror circuit formed by 717 and the current mirror circuit formed by the transistors 718, 719, 720, 721, 722 are both in the cutoff state, and the transistors 701, 702, 703, 70
No base current is supplied to 4,705.

However, since the base current is supplied only to the transistor 706 through the transistor 723, the transistor 706 is turned on. However, since all of the transistors 702, 703, 705 are in the off state, no current for generating a rotational force flows through the stator windings 1, 2, 3 in FIG. A current required for detecting the stationary position of the rotor is supplied to the Hall IC 6 via the.

At the time of starting the motor, the initialization signal input terminal j
Since the level of 2 shifts to'H ', the transistor 723
Is immediately turned off, but the stator windings 1 to 3 are immediately energized in the energization mode based on the position detection information at the time of stop, and the Hall IC 6 continues to be supplied with the current required to detect the rotational position.

Even if the power supply to the Hall IC 6 is temporarily interrupted at the time of starting the motor due to the influence of the inductance of the stator windings 1 to 3, the position detection signal is a logic circuit using a flip-flop (for example, as shown in FIG. (The circuit shown in 6) is supplied to the drive signal generation circuit,
Information before that is retained.

Next, FIG. 13 is a circuit connection diagram showing a concrete configuration example of the extraction circuit 600 of FIG.
4 and s4 are the signal lines 100n and 100s of FIG. 2, respectively.
And the position detection signal shown in FIGS. 14A and 14B is supplied.

The signal supplied to the input terminal s4 is NAND
A first flip-flop formed by the gate 601 and the NAND gate 602, a second flip-flop formed by the NAND gate 603 and the NAND gate 604, and an NA.
The signal supplied to the input terminal n4 is used as the reset signal of the third flip-flop by the ND gate 605 and the NAND gate 606, and is used as the output update signal of the first to third flip-flops. Therefore, in the configuration of FIG. 13, an output signal appears at the output terminal B when the level of the n4 terminal changes three times while the level of the input terminal s4 is “L”.

FIGS. 14C, 14D, and 14E show the output signal waveforms of the NAND gates 601, 603, and 605 of FIG. 13, respectively. An absolute position detection signal can be obtained once per rotation.

Now, returning to FIG. 2, the outline of the operation described so far is summarized as follows.

First, when the rotor is stopped, only the W terminal among the U terminal, the V terminal, and the W terminal is at a high potential, and the Hall IC 6 passes through the stator winding 3 and the current limiting resistor 8. A current is supplied to the rotor to detect the stationary position of the rotor, and the Hall IC 6 generates an output of high potential, intermediate potential, or low potential according to the stationary position.

The motor block 1 is used in the embodiment.
In order to minimize the number of connecting lines between 0 and other circuit blocks, the Hall IC 6 is fed with power from the midpoint of the three-phase stator winding, and its output is sent as a ternary signal. Even if the Hall IC is fed from a separately provided feeding terminal and the number of its output terminals is increased to two or three,
It does not depart from the purpose of the invention.

The signal lines 100n, 100s, 100z are distributed by the distributor 100 according to the output level of the Hall IC 6.
One of the two is activated and the position detection information is supplied to the drive signal generating circuit 300 via the sequential circuit 200. However, the sequential circuit 2 is supplied until the rotor starts rotating.
00 operates simply as a buffer.

Based on the position detection information supplied to the drive signal generation circuit 300, the drive signal generation circuit 300 and the drive circuit 700 set any one of the U terminal, the V terminal, and the W terminal to the “H” level, The rest is set to the “L” level to generate a rotation torque in the rotor.

At this time, the Hall IC 6 is located at a position where the electrical angle of rotation is 60 ° in FIG.
Assuming that it is accidentally stopped at the boundary of the poles or at the position where the rotating electrical angle is 390 °, in any case, the Hall IC 6 produces the same output as when facing the non-magnetized portion of the identification band 5, Since the stator windings 1 to 3 are energized based on that information, the rotor will generate rotational torque in the opposite direction, as can be seen from the characteristic curve in FIG. 10 (b). However, regular position detection information is obtained by moving the rotor only slightly, and thereafter, the order circuit 200 regulates the order in which the position detection signals are received, so that smooth rotation can be maintained.

When the rotation speed of the rotor increases to a certain extent, the potential of the E terminal in FIG. 2 decreases, and the drive signal generating circuit 3
No. 00 switches the energization form to the stator windings 1 to 3 to the three-phase full-wave drive, so that the rotation torque characteristic of the rotor is shown in FIG.
It becomes like the envelope of the characteristic curve shown in.

Now, in the DC non-commutator motor of the present invention,
Since the energization switching to the stator windings 1 to 3 is performed slowly by using the sawtooth wave generated by the slope generation circuit 500 whose specific example is shown in FIG. It is also possible to prevent each stator winding and stator frame from acting like a speaker to generate noise during rotation, and to generate electric noise due to spike pulses of each stator winding. It is also possible to prevent the IC or other semiconductors from being destroyed by the surge voltage.

Further, since only the capacitor 525 is required as an individual component for performing the gradual switching of energization, and it is not necessary to pass a large current through the time constant circuit of the monostable multivibrator, the resistance value of the resistor 520 is reduced. 10
It can be set to kΩ or more, and as a result, a large time constant can be obtained even with a small capacity capacitor.

Further, if this capacitor is formed in the IC chip (for example, if the circuit is constituted by MOS IC, the input impedance becomes very large, the IC
A large time constant can be obtained only by forming a capacitor of several PF in the chip.) If the slope generation circuit 500 is configured by a combination of a counter and a digital-analog converter, it is possible to eliminate capacitors as individual components. it can.

FIG. 15 is a circuit connection diagram showing another configuration example of the slope generation circuit 500. The same elements as those in FIG. 1 are designated by the same figure numbers or the same symbols.

A clock signal is externally supplied to the input terminal C1 of FIG. 15 (for example, in a video tape recorder or a floppy disk drive, various clocks are used in the system, so an appropriate one should be selected. Yes, toggle flip-flop 527,
A 4-bit up counter constituted by 528, 529 and 530 counts this clock signal.

On the other hand, resistors 531, 532, 533 and 53
4, diodes 535, 536, 537, 538, 51
8. The resistor 539 constitutes a simple digital-analog converter, and the potential of the output terminal g1 rises stepwise as the count value of the counter increases.

When all the outputs of the toggle flip-flops 527 to 530 become "H", the NAND gate 540 resets the flip-flops of the NAND gate 509 and the NAND gate 510, and as a result, the toggle flip-flops 527 to 5 are transmitted via the inverter 511.
Since the reset signal is supplied to 30, the counting operation is stopped and the toggle flip-flops 527 to 530
Will be all'L '. When the leading edge or trailing edge of the output signal of the amplifier 501 arrives, the flip-flop is set and the counting operation of the counter is restarted.

In this way, the NAND gate 540 and the NAN
D gates 509, 510, inverter 511, NAND
The gates 502 to 504, the inverter 505, and the NAND gates 506 to 508 form a controller that controls the counting operation of the counter. Needless to say, the signal waveforms shown in FIGS. 9E and 9F appear at the output terminals g1 and h1 of FIG.

By the way, the slope generation circuits shown in FIGS. 8 and 15 both generate a sawtooth wave having a period in synchronization with the output signal from the power generation winding 7, but finally the sawtooth wave is generated. Since the slope portion is used, the output signal of the slope generation circuit 500 shown in FIG. 2 does not necessarily have to be a sawtooth wave, and may be a triangular wave or a trapezoidal wave having a similar slope portion. .

[0127]

As is apparent from the above description, the DC non-commutator motor of the present invention has a plurality of stator windings (in the embodiment, DC non-commutation motors having three-phase stator windings 1 to 3). Although a child motor is shown, the number of phases is not limited), a rotor provided with a permanent magnet 4 having a plurality of magnetic poles facing the stator winding, and a phase detected by detecting a rotational position of the rotor. Of position detection means for generating a plurality of different position detection signals (in the embodiment, the position detection means is composed of the Hall IC 6 and the distributor 100), and a control signal input terminal E. Drive means for supplying a current having a magnitude depending on the control signal to the stator winding based on the output signal of the drive signal (in the embodiment, the drive means is composed of the drive signal generation circuit 300 and the drive circuit 700). Equipped with An output transistor 701 to which a force current is supplied to the stator winding and a current mirror circuit are formed together with the output transistor, and a current 1 / K of the output current (K> 1) is supplied to the first resistor 709. The mirror transistor 707 to be supplied, the second resistor 710 to which the energization command current to the stator winding is supplied, and the voltage across the first resistor and the voltage across the second resistor are compared. Control circuit for controlling the input current of the output transistor (in the embodiment, transistor 7
(22, 731, 732, 733, 734 constitute a control circuit), and the output part of the driving means is constituted by the output circuit, the current amplification factor of the output stage is affected by the variation of the current amplification factor of the transistor itself. It can be set arbitrarily without receiving it, and has a great effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a motor portion configured to implement the present invention.

FIG. 2 is a block diagram of a DC non-commutator motor configured to carry out the present invention.

[Figure 3] Hall IC internal circuit connection diagram

FIG. 4 is a signal waveform diagram corresponding to a magnetization pattern of an identification band for explaining a processing operation of a position detection signal.

FIG. 5 is a flowchart for implementing a sequential circuit by software.

FIG. 6 is a circuit connection diagram showing a configuration example of a sequential circuit.

FIG. 7 is a circuit connection diagram showing a configuration example of a sequential circuit.

FIG. 8 is a circuit connection diagram showing a configuration example of a slope generation circuit.

FIG. 9 is a signal waveform diagram for explaining the processing operation of the position detection signal.

FIG. 10 is a torque characteristic diagram for explaining the torque characteristic of the motor and switching of energization.

FIG. 11 is a circuit connection diagram showing a specific example of a drive signal generation circuit.

FIG. 12 is a circuit connection diagram showing a drive circuit of a DC non-rectifier motor according to an embodiment of the present invention.

FIG. 13 is a circuit connection diagram showing a configuration example of an extraction circuit.

FIG. 14 is a signal waveform diagram of each part of the circuit shown in FIG.

FIG. 15 is a circuit connection diagram showing another configuration example of the slope generation circuit.

[Explanation of symbols]

1, 2, 3 Stator winding 4 Permanent magnet 6 Hall IC 100 Distributor 300 Drive signal generation circuit 500 Slope generation circuit 700 Drive circuit 701, 707, 722, 731, 732, 733, 7
34 Transistors 709,710 Resistance

Claims (1)

[Claims] 1. A rotor including a plurality of stator windings and a permanent magnet having a plurality of magnetic poles facing the stator windings,
Position detecting means for detecting a rotational position of the rotor and generating a plurality of position detecting signals having different phases; and a stator winding having a control signal input terminal and based on an output signal from the position detecting means. A drive means for supplying a current having a magnitude depending on the control signal, an output transistor whose output current is supplied to the stator winding, the output transistor and a current mirror circuit are formed, and K
A mirror transistor for supplying a first (K> 1) current to the first resistor, a second resistor for supplying an energization command current to the stator winding, and a second resistor for connecting both ends of the first resistor. The output section of the driving means is constituted by a control circuit which compares the voltage and the voltage across the second resistor and controls the input current of the output transistor so that the two are balanced. Child motor.