JP2502680B2 - Brushless motor drive - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor drive device that performs a step operation.

2. Description of the Related Art Conventionally, there has been a brushless DC motor as disclosed in JP-A-54-57111.

The conventional brushless DC motor will be described below.

FIG. 11 shows a conventional brushless DC motor. In Fig. 11, W ₁ , W ₂ , W ₃ and W ₄ are four partial windings, the ends of which are grouped together into a star-shaped connecting point, which is led to the positive pole of the power supply and each partial winding. Switch at free end of line
It is led to the negative electrode of the power source through S _{1 to} S ₄ . R is a rotor. The direction of the magnetic pole N-S is indicated by an arrow 111, and H ₁ , H ₂
Indicates two rotor position detectors. The commutation is performed so that the rotor R rotates in the direction opposite to the rotation of the timepiece, and the commutation angles are 45 °, 135 °, 225 °, 315 °. When the winding W ₃ is energized, the roller R moves in the range of angles 45 ° to 135 °, and the windings W ₄ , W ₁ , W ₂
When the respective currents are sequentially energized,
It is moved in the range of °, 225 ° ~ 315 °, 315 ° ~ 45 °. When the winding W ₂ is energized, the rotor R is moved in the range of 315 ° to 45 °. If the state of the commutation signal at this moment is maintained, the rotor R is held in the state of being directed towards the energized winding W ₂ . But at this point a new signal has already arrived, which tries to close the winding W ₃ . To avoid this, an intermediate storage device 112 is provided, which stores the commutation signal to the winding W ₃ until the next step pulse clears the already existing commutation signal.

This circuit is shown in FIG. 11b. 113 is two Hall elements H
₁ , a rotor position detector composed of H ₂ , 114 is an amplifier for amplifying the output of the Hall element, 115 is a selection circuit for controlling the rotor positions of the switches S _{1 to} S ₄ from the output of the amplifier 114, 11
6 is a rotor, 117 is a commutation circuit, 118 is an OR circuit, 119 is a preset counter, 1110 is an AND circuit, and 1111 is an OR circuit. The output terminal of the selection circuit 115 is connected to the input terminal of the intermediate storage device 112, and the input signal of the intermediate storage device 112 is sent to the commutation circuit 117 connected to the output terminal based on the control signal. This state is maintained until the next control signal arrives at the input terminal of the intermediate storage device 112. In this way, the selection circuit 115 energizes the winding W ₂ and thus holds the rotor 116 in the direction of this winding, which is maintained until the intermediate storage device 112 receives a new control signal. At this time, the selection circuit 115 has already selected energization of the winding W ₂ corresponding to the rotor position.
This commutation signal is repeatedly controlled by the intermediate storage device 112 to obtain continuous rotor motion. Further commutation signal
A step pulse is induced to the selection circuit 115 each time S _{1 to} S ₄ changes, and an external preset counter 119 is supplied via the OR circuit 1111.
Lead to. On the other hand, the step pulse is directly stored in the intermediate storage device 11
2 to the input terminal of the rotor 116, which causes a step motion of the rotor 116. To use such a motor for position setting, an external preset counter 119 is provided, which determines the number of angular steps to be performed. As a result, the step pulse is supplied to the control input terminal of the intermediate storage device 112 through the AND circuit 1110 and the OR circuit 1111. One signal is sent from the preset counter 119 to the AND circuit 1110 until the predetermined position is obtained. Each step pulse is introduced into the intermediate storage device 112 in a short time until the predetermined number of steps is obtained. For this reason, a new commutation sequence is generated on the output side of the intermediate storage device 112, and thus the commutation circuit 117.
Occur continuously. The motor rotates one angular step each according to each step pulse.

However, in the above-mentioned conventional method, it is impossible to control the rotation by designating the angle such as stopping the motor at a required angle. Therefore, the motor cannot be used to move the head of the compact cassette tape recorder and control the pressure contact position of the pinch roller. This is because the position control for pressure contact requires a function of stopping and holding the rotation of the motor at a designated angle. Further, it is necessary to move the head pinch roller at high speed and to have a high torque that can withstand the load torque during each movement and pressure contact.

However, in the above-mentioned conventional configuration, the Hall element, which is the position detector of the roller, needs to be at least as many as the number of phases of the motor, and the intermediate storage device that stores the next step pulse is required. At the same time, since two or more step pulse sequences corresponding to the angle to be rotated cannot be stored in the intermediate storage device, it is not possible to correspond to step pulse sequences with short intervals. Further, the step angle number of motor rotation is only the number of coils of the motor. Since it is dependent, detailed step operation is impossible. In addition, there is a drawback that the rotor of the motor cannot be surely stopped at the designated angle.

The present invention has been made in order to solve the above-mentioned conventional problems. The number of Hall elements is equal to or less than the number of phases of a motor and can correspond to a step pulse sequence with a short interval. A brushless motor drive that does not require an intermediate storage device that enables finer step operation than when using a motor with the same number of phases without depending only on the number of coils and that can surely stop at a specified angle. It is provided.

Means for Solving the Problems To achieve this object, a brushless motor driving device according to the present invention comprises a clock signal generating means for generating a clock signal of a predetermined cycle, and a rotor position detecting means for detecting a rotational position of a rotor. And phase detecting means for detecting a phase difference between the clock signal and the output of the rotor position detecting means,
Synchronous clock signal generating means for changing the duty ratio of the clock signal which is the output of the clock signal generating means based on the output of the phase detecting means, current driving means for supplying a current to each coil of the stator, and synchronous clock signal generating means. Timing control means for controlling the timing and duration of the current flow through each coil by using the current drive means in synchronization with the synchronous clock signal which is the output of the clock, and the clock count for counting the synchronous clock signal from an arbitrary time point by an external command. Means, a count detecting means for detecting that the count output of the clock counting means is a predetermined count number, and a synchronous clock when the count detecting means detects that the count output of the clock counting means matches the predetermined count number. Hold the output of the timing control means based on the signal for a predetermined time And a hold / reset means for resetting the output of the timing control means after a predetermined time and for giving a signal to the timing control means when the output of the count detection means is not present. There is.

With this configuration, the brushless motor can be operated like a stepping motor in synchronization with the synchronous clock signal, and the synchronous clock signal is generated based on the output of the rotor position detecting means, so that the motor is step-operated. However, the step-out phenomenon in which the motor operation does not follow the step pulse does not occur. Further, the step angle of the motor does not depend only on the number of coils of the motor, and fine step operation is possible. Further, the clock counting means, the count detecting means, and the hold / reset means can surely stop the motor at the designated angle.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a brushless motor driving device according to an embodiment of the present invention.

In FIG. 1, 1 is a clock signal generation circuit for generating a clock signal of a predetermined cycle, 2 is a rotor position detection circuit for detecting the position of a rotor, 3 is an output of the clock signal generation circuit 1 and a rotor position detection circuit 2. A phase detection circuit that detects a phase difference from the output, 4 is a synchronous clock signal generation circuit that changes the duty ratio of the clock signal based on the output of the phase detection circuit 3, 5 is a clock counter that counts the synchronous clock signal, and 6 is A count detection circuit that detects that the count output of the clock counter 5 is a predetermined count number, 7 is a timing control circuit that controls the timing and duration of the current flow to each coil of the stator of the brushless motor 10, and 8 is the count detection circuit. The count output of the clock counter 5 has reached a predetermined count number based on the output of the circuit 6. A hold / reset circuit for holding the output of the timing control circuit 7 based on the synchronous clock signal at the time of detection for a predetermined time and resetting the output after holding the output for a predetermined time. A current drive circuit that supplies current to each coil, and 10 is a brushless motor.

In this embodiment, as the brushless motor 10, a three-phase brushless motor in which each coil of the stator is Y-connected is used,
For example, the Hall element which is the rotor position detection sensor is 1, 2, 3 for rotating the brushless motor 10 by 90 ° in one cycle of the synchronous clock signal and stopping the rotation when the brushless motor 10 is further rotated by 90 °. The case will be described.

2A and 2B show the positional relationship between the rotor position detection circuit 2, the rotor, the stator coil, and the Hall element.
FIG. 3 is a waveform diagram for explaining the operation of FIG.
5 and 5 are circuit diagrams showing the phase detection circuit 3 and the synchronous clock signal generation circuit 4, FIG. 6 is a waveform diagram for explaining the operation of the phase detection circuit 3 and the synchronous clock signal generation circuit 4,
7 is a circuit diagram showing the timing control circuit 7, FIG. 8 is a circuit diagram showing the clock counter 5, the clock detection circuit and the hold / reset circuit 8, and FIG. 9a is a current drive circuit 9.
FIG. 9B is a coil connection diagram of the brushless motor 10, and FIG. 10 is a waveform diagram for explaining the operation of the synchronous clock signal, the timing control circuit 7 and the hold / reset circuit 8.

Next, the operation of the brushless motor drive device of this embodiment will be described.

The clock signal generating circuit 1 shown in FIG. 1 generates a clock signal having a duty ratio of 50% shown in FIG.
The rotor position detection circuit 2 of FIG. 1 has three comparators 21, 22, 23 and two EX-Os with the circuit configuration shown in FIG. 2a.
It consists of R gates 24 and 25. Further, the three-phase brushless motor in the present embodiment is, as shown in FIG. 2b, a rotor 26 having eight magnetic poles, six stator coils 27 in which opposite sides are connected in series, and three Hall elements H ₁ , It is composed of H ₂ and H ₃ . The operation of the rotor position detection circuit 2 is shown in FIG. The output of the Hall element has a certain direct current level (determined by the bias current of the Hall element) and the output of opposite phase
H ^+, H ^- with a. By inputting these two signals H ⁺ and H ⁻ to the input of the comparator, the zero cross point of the circled portion in FIG. 3a, that is, the boundary point of the magnetic poles of the rotor is detected. Therefore, when the outputs obtained by comparing the outputs of the three Hall elements with the three comparators 21 to 23 are combined by the two EX-OR gates 24 and 25, a signal corresponding to the rotor rotation angle of 15 ° is obtained. Waveforms at various parts of FIG. 2a are shown in FIG. 3b. In this case, the case of three Hall elements has been described, but the rotor position detection circuit 2 can be configured with only one comparator 21 in the case of one Hall element, and two comparators and one in the case of two Hall elements.
It can be constituted by an EX-OR gate, and the output of the rotor position detection circuit 2 in each case becomes the signals A and D shown in FIG. 3b.
Next, the phase detection circuit 3 shown in FIG.
FIG. 4 shows a circuit for comparing the output of the clock signal generating circuit 1 and the phase of the output of the rotor position detecting circuit 2, and converting the output of the clock signal generating circuit 1 for phase comparison.

This is composed of four JK flip-flops 41 to 44, one NAND gate 45 and one data selector 46, and drives 3
The phase comparison clock signal corresponding to the number of Hall elements of the phase brushless motor is generated. This phase comparison clock signal is the same as the clock signal output from the clock signal generation circuit 1 when the number of Hall elements is 0, and the waveform shown in FIG. 6 when the number of Hall elements is 1 to 3. become that way. The phase difference between the phase comparison clock signal and the output of the rotor position detection circuit 2 is detected by the phase detection circuit 3, and the synchronous clock signal generation circuit 4 generates the synchronous clock signal based on this output. The phase detection circuit 3 and the synchronous clock signal generation circuit 4 are shown in FIG.

FIG. 5 shows a phase detector 51 for detecting a phase difference between positive edges of two signals, a phase detector 52 for detecting a phase difference between negative edges of two signals, and two phase detectors 51, 52. Three OR gates that generate a synchronous clock signal based on the output
53 to 55, consisting of one NOR gate 56 and one AND gate 57.
The operation of FIG. 5 will be described with reference to FIG. However, when the number of Hall elements is 0, the synchronous clock signal is the same as the clock signal. As can be seen from FIG. 6, the phase detection circuit 3
The synchronous clock signal generation circuit 4 converts the clock signal output from the clock signal generation circuit 1 into a phase comparison clock signal, and compares the phase difference between this signal and the output signal of the rotor position detection circuit 2. Then, based on this phase difference, a synchronous clock signal in which the duty ratio of the clock signal is changed is generated. Therefore, based on this synchronous clock signal, the timing control circuit 7 outputs a signal for controlling the timing and the period during which the current flows in each coil of the stator. The circuit structure of the timing control circuit 7 is shown in FIG. This timing control circuit comprises four JK flip-flops 71 to 74, six D flip-flops 75 to 710, three AND gates 711 to 713, and one inverter. The timing control circuit 7 generates three-phase clocks, each of which has six cycles of the input synchronous clock as one cycle, which do not overlap each other, by the four JK flip-flops 71 to 74. The three-phase clock signals thus generated are delayed by the six D flip-flops 75 to 710 based on the synchronous clock signals, and the outputs are φ ₁ to φ ₆ . These φ _{1 to} φ ₆ are outputs of the timing control circuit 7. Based on the output signal of the timing control circuit 7, the current driving circuit 9 supplies a current to each coil of the stator to drive the brushless motor 10. The current drive circuit 9 is shown in FIG. The current drive circuit 9 is composed of six transistors Q _{1 to} Q ₆ , and is directly driven by the outputs φ _{1 to} φ ₆ of the timing control circuit 7 shown in FIG. Then, as shown in FIG. 9b, a current is supplied to the Y-connected brushless motor coil. Further, the clock counter 5 counts the synchronous clock signal output from the synchronous clock signal generating circuit 4 based on a count start signal given from the outside. Then, the count detection circuit 6 detects that the count value output from the clock counter 5 is a predetermined count number. And hold / reset circuit 8
Outputs a control signal to the timing control circuit 7 based on the output of the count detection circuit 6. That is, when the count detection circuit 6 detects that the output of the clock counter 5 is the predetermined count number, the output of the timing control circuit 7 at the time of detection is held for a predetermined time, and after the predetermined time, the timing control circuit 7 outputs The hold / reset circuit 8 gives a signal for resetting the output to the timing control circuit 7.
The clock counter 5, the count detection circuit 6 and the hold / reset circuit 8 are shown in FIG. In FIG.
The clock counter 5 and the count detection circuit 6 have three
JK flip-flops 81 to 83, NAND gate 87, AND gate 88
The hold / reset circuit 8 comprises an SR flip-flop 84, a mono-multivibrator 85 and a D flip-flop 86.

The above series of operations will be described with reference to FIG. The timing control circuit 7 operates based on the clock signal output from the clock signal generation circuit 1. Then, based on the output of the timing control circuit 7, the current drive circuit 9 supplies a current to the brushless motor 10. This causes the brushless motor 10 to rotate. Therefore, the rotor position detection circuit 2 detects this rotation. Then, the phase detection circuit 3 converts the clock signal output from the clock signal generation circuit 1 into a phase comparison clock signal, and this signal and the rotor position detection circuit 2
The phase difference with the output signal of is detected. This phase detection circuit 3
The synchronous clock signal generation circuit 4 changes the duty ratio of the clock signal on the basis of the output of the synchronous clock signal to generate the synchronous clock signal. In the present embodiment, this synchronous clock signal is the same as the clock signal when the number of Hall elements is zero.
When the number of Hall elements is one, the time required for the rotor to rotate by 45 ° is equal to the period sum of three pulses of the synchronous clock. When the number of Hall elements is two, the time required for the rotor to rotate 30 ° is equal to the period sum of two pulses of the synchronous clock. Furthermore, if the number of Hall elements is 3, the rotor is 15 °
The time required for rotation and the cycle of the synchronous clock are equal. The timing control circuit 7 outputs outputs φ _{1 to} φ ₆ based on the synchronous clock signal. Based on the outputs φ _{1 to} φ ₆ , the transistors Q _{1 to} Q ₆ of the current drive circuit 9 are turned on to drive the brushless motor 10. Further, as shown in FIG. 10, after the brushless motor 10 rotates by 60 °, a count start signal is given to the clock counter 5. As a result, the clock counter 5 counts the synchronous clock signal.
By the way, since the clock counter 5 is a hexadecimal counter as shown in FIG. 8, the brushless motor 10 outputs a count signal at 150 ° rotated 90 ° from the rotational position of 60 °. The count detection circuit 6 detects this by the count detection circuit 6 having a predetermined count number. Based on this detection output, the hold / reset circuit 8 outputs the output φ ₁ to the timing control circuit 7 when the count detection circuit 6 detects that the count number is a predetermined number, that is, when the rotor rotation angle is 150 °.
A signal for holding φ ₆ for a predetermined time is given to the timing control circuit 7. Then, after a predetermined time, the hold / reset circuit 8 gives a signal for resetting the outputs φ _{1 to} φ ₆ of the timing control circuit 7 to the timing control circuit 7. With this, when the brushless motor 10 is rotated by 150 °, the rotation can be surely stopped.

The clock signal is the output of the clock signal generation circuit 1. However, if the clock signal output from the clock signal generation circuit 1 has the same cycle and the same duty ratio, an external clock given from the outside is used as the clock signal. It can be omitted.

As described above, according to the present invention, the clock signal generating means for generating a clock signal of a predetermined cycle, the rotor position detecting means for detecting the rotational position of the rotor, the clock signal and the output of the rotor position detecting means. Of the phase detection means for detecting the phase difference of, the synchronous clock signal generation means for changing the duty ratio of the clock signal which is the output of the clock signal generation means based on the output of this phase detection means, and the current to each coil of the stator. A current driving means for flowing, a timing control means for controlling a timing and a period for flowing a current to each coil in synchronization with the synchronous clock signal, and a synchronous clock signal are counted from an arbitrary time point by an external command. Check that the clock count means and the count output of the clock count means match the predetermined count number. The output of the timing control means based on the synchronous clock signal when detected by the und detection means is held for a predetermined time, the output of the timing control means is reset after the predetermined time, and the output of the timing control means is output when there is no output of the count detection means. By providing a hold / reset means for giving a signal for passing to the timing control means, the brushless motor can be operated like a stepping motor in synchronization with the synchronous clock signal, and based on the output of the rotor position detection means. Since the synchronous clock signal is generated by the stepping motor, the step-out phenomenon does not occur even if the motor is stepwise operated. Further, the step angle of the motor does not depend only on the number of coils of the motor, and fine step operation is possible. In addition, the number of Hall elements that are rotor position detectors is less than or equal to the number of phases of the motor, and the number of Hall elements can be reduced. Further, the clock count means, the count detection means, and the hold / reset means have a great industrial effect such that the motor can be reliably stopped at the designated angle.

[Brief description of drawings]

FIG. 1 is a block diagram of a drive device for a brushless motor in one embodiment of the present invention, FIG. 2 is a state diagram showing a positional relationship between a rotor position detection circuit and a rotor, a stator coil, and a Hall element, and FIG. Waveform diagram for explaining the operation of the figure,
FIG. 4 is a circuit diagram of a phase comparison clock signal generation circuit which is a part of the phase detection circuit, FIG. 5 is a circuit diagram showing a phase detection circuit and a synchronous clock signal generation circuit, and FIG. 6 is FIG. 5 is a waveform diagram for explaining the operation of FIG. 5, FIG. 7 is a circuit diagram of a timing control circuit, FIG. 8 is a circuit diagram showing a clock counter, a clock detection circuit and a hold / reset circuit, and FIG. 9 is a current drive circuit and FIG. 10 is a circuit diagram showing coil connection of a brushless motor, FIG. 10 is a waveform diagram for explaining the operation of FIGS. 7 and 8, and FIG. 11 is a configuration diagram of a conventional brushless DC motor. 1 ... Clock signal generation circuit, 2 ... Rotor position detection circuit, 3 ... Phase detection circuit, 4 ... Synchronous clock signal generation circuit, 5 ... Clock counter, 6 ... Count detection circuit, 7 ... Timing control Circuit, 8 ... Hold / reset circuit, 9 ... Current drive circuit, 10 ... Brushless motor.

Front page continued (72) Inventor Daisaburo Kubota 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Makoto Miyamoto 1006 Kadoma, Kadoma City Osaka Prefecture ) Inventor Yuji Nagata 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 56-129587 (JP, A) JP 57-162978 (JP, A) JP A 61-236384 (JP, A)

Claims (3)

(57) [Claims] 1. A clock signal generating means for generating a clock signal of a predetermined cycle, a rotor position detecting means for detecting a rotational position of a rotor, and a phase difference between the clock signal and an output of the rotor position detecting means. Phase detecting means, synchronous clock signal generating means for changing the duty ratio of the clock signal based on the output of the phase detecting means, current driving means for supplying a current to each coil of the stator, and the synchronous clock signal generating means. Timing control means for controlling the timing and duration of the current flowing through the coils in synchronization with the synchronous clock signal which is the output of the current driving means, and counting the synchronous clock signal from an arbitrary time point by an external command. The clock counting means and the count output of the clock counting means are a predetermined count number. And the output of the timing control means based on the synchronous clock signal when the count detection means detects that the count output of the clock count means coincides with the predetermined count number for a predetermined time. When the output of the timing control means is reset after the predetermined time and there is no detection output of the count detection means, a hold / reset means for giving a signal for passing the output of the timing control means to the timing control means. A drive device for a brushless motor, comprising: 2. The brushless motor drive device according to claim 1, wherein the sum of the cycles of the predetermined number of clocks of the synchronous clock signal is the same as the time required for the rotor to rotate a predetermined angle. 3. The timing control means, based on the synchronous clock signal output from the synchronous clock signal generating means, the timing of the current supplied to each coil of the stator for rotating the rotor by a predetermined angle in one cycle of the synchronous clock. 2. The brushless motor driving device according to claim 1, wherein the period is determined and the output signal of the timing control means is output, held and reset by an external signal.