JPH01122388A - Sensorless brushless motor - Google Patents

Abstract

PURPOSE:To prevent a motor against malfunction in switching the conduction, by deciding the conductive switching position with the quantity of delay in proportion to the motor speed. CONSTITUTION:A sensorless brushless motor is of a two-phase bidirectional conduction type, in which two-phase coils La-Lb are switched for bidirectional conduction with a switching circuit 1. Pulse signals S1-S2 from this circuit 1 are given to DFF 3-4 through a mask circuit 8, where the mask, etc., is controlled with the control data in proportion to the motor speed from a microprocessor 7. A delay clock DCK is given to the clock input of FF 3-4 and 45 deg. delayed pulse signals Ha-Hb are given to a driving pulse generation logic 2 for logical processing, through which bidirectional conductive pulses P1-P8 in every 90 deg. are formed. With these pulses transistors are turned ON and OFF for switching conduction. Even if the detecting period is extended or reduced, the conductive angle is set up at a predetermined electric angle with the variable delay in proportion to the speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brushless motor without a position detection sensor.

[Summary of the invention]

The rotation reference position of the rotor is detected based on the induced voltage of the excitation coil, and a variable delay based on the reference position and motor speed information is used to optimally determine the energization switching point of the excitation coil. This is a sensorless brushless motor that performs signal masking to prevent the noise generated by the sensor from interfering with the detection of the reference position, and achieves operating performance equivalent to that of a motor using sensors.

[Conventional technology]

Brushless motors are generally configured to detect the rotational position of a rotor using a position sensor such as a Hall element, and generate switching pulses for phase switching based on the detection signal. However, providing a Hall element
Increased parts costs, increased number of wires, and installation caused increased man-hours for position adjustment.

Therefore, the applicant of this application has already proposed a brushless motor that does not require a position sensor (for example, Japanese Patent Application No. 12541/1983).
No. 3), in this brushless motor, the induced voltage of the stator coil is detected to form a pulse indicating the rotational position of the rotor, and a fixed delay is applied to this pulse to form a timing pulse for energization.

[Problem that the invention seeks to solve]

The above-mentioned sensorless brushless motor uses a fixed delay device, such as a monomulti, to form the timing pulse for energization, so it can rotate over a wide range of speeds, such as in a constant linear velocity (CLV) type video disk player. However, it could not be applied to motors that are controlled over the entire range.

Furthermore, when starting the motor, a special energizing pulse was generated regardless of the rotor's rotational position, so the energizing angle at startup was not completely synchronized with the rotor's rotational angle, resulting in poor startup characteristics. .

In addition, since the rotor's rotational position is detected based on the induced voltage of the excitation coil, spike-like noise generated in the coil at the coil's energization switching point and residual noise from the detection system may mix into the rotational position detection signal, causing the energization to change. There was an inconvenience that the switching angle, energization period, and energization direction were not stably determined.

The present invention provides a sensorless brushless motor that solves these problems.

[Means for solving problems]

The sensorless brushless motor of the present invention has an exciting coil L
A circuit such as a zero cross comparator 19.2° that outputs a reference position of rotor rotation based on the induced voltage EaSEb of a5Lb (O'', 180''l) of the magnet,
a delay circuit 5 that forms a delay pulse delayed by a predetermined amount from the reference position; a circuit (drive pulse generation logic 2) that generates an energization switching signal for the excitation coils La and Lb (7) based on the delay pulse; A circuit (microprocessor 7) is provided that detects the rotational speed of the motor, controls the delay amount of the delay circuit, and adjusts the energization switching position according to the motor speed.

Furthermore, a mask circuit 8 is provided which forms a mask signal based on the delayed pulse to suppress the pseudo pulse P in the detection output of the reference position.

[For production]

Although the detection cycle of the reference position of rotor rotation expands or contracts in response to changes in the speed of the motor, the energization angle with respect to the reference position is always set to a predetermined electrical angle due to the variable delay depending on the speed. Therefore, at the time of startup or when controlling the speed variably, the energization switching is performed optimally and without loss at any speed.

Furthermore, based on the output of the delay circuit 5, a mask signal with a phase that includes the current switching position can be created in accordance with the motor speed, and the detection of the reference position of rotor rotation can be prevented by noise generated in the excitation coil. Therefore, the delay circuit circuit 5 operates based on correct reference position detection and determines the energization switching point and the mask position.

〔Example〕

FIG. 1 shows a schematic block diagram of a drive circuit for a sensorless brushless motor according to the present invention. The brushless motor of this embodiment is of a two-phase bidirectional energization type, and as shown in FIG. (22.5 degrees in mechanical angle) two-phase coils La and Lb are arranged. Each coil La% Lb is electrically in phase (22.5 degrees in electrical angle).
Series coil La2 placed at a position (an integral multiple of 60°)
, Lag (Lb+-, Lbt), and the winding pitch of each individual coil is 180° in electrical angle (4 in mechanical angle).
5゛).

The two-phase coil La% Lb is bidirectionally (reciprocally) energized by the switching circuit 1 shown in FIG. That is,
As shown in FIG. 2, the load (coil La.

Transistors 11 to 11 bridge-connected to Lb)
18 is turned on at each electrical angle of 90 degrees by drive pulses P1 to P8, and both ends of each coil La5Lb are alternately connected to the power source and ground to drive the motor.

When the motor is rotating, sinusoidal induced voltages Ea and Eb with a phase difference of 90' are generated at both ends of each coil La5Lb, as shown in the waveform diagram of FIG. 4A. This induced voltage E
The waveforms of a and Eb are shaped at the zero cross, that is, at the neutral point potential of the alternating current, by comparators 19 and 20, each of which has two terminals connected to both ends of the coil La%Lb. Therefore, as shown in FIG. 4B, from each comparator 19, 20, pulse signals S1 and S2 with a 90° phase difference, which have the same period and phase as the induced voltage E a sEb and whose high level and low level correspond to the AC polarity, are obtained. It will be done. This pulse signal is
a shows the rotational reference position of the rotor with respect to SL b.

The pulse signals S1 and S2 are supplied to the delay circuit 5, and as shown in FIG. 4C, a delayed clock DCK whose rise is delayed by a time T from both rising edges of S1 and S2 is formed. Furthermore, the falling edge of CK is synchronized with Sl and S2. 0 time T corresponds to 45 degrees in electrical angle. Therefore, without a rotational position sensor, it is possible to move 45 degrees from the magnetic pole boundary, which is the reference position of the rotor magnet 21. An energization angle of 90° width can be set with the position as the leading edge. As described below, time T
is variably controlled by the microprocessor 7 so that the electrical angle is always maintained at 45° even if the rotational speed of the motor changes.

In FIG. 1, pulse signals S1 and S2 from a switching circuit 1 are applied to a D flip-flop 3.4 via a mask circuit 8. Note that the mask circuit 8 is a circuit that removes noise in a portion other than the zero cross position of E a % E b included in the pulse signals S1 and S2.

Since noise occurs at specific positions such as current switching points, the mask position and the mask are controlled by control data from the microprocessor 7 according to the motor speed.

The above-mentioned delayed clock DCK is applied to the clock input of the flip-flop 3.4. Therefore, a 45° delayed pulse signal (2% Hb) is obtained from the output of the flip-flop 3.4 as shown in the fourth diagram.
a and H'b are applied to the driving pulse generation logic 2, and through logical processing (encoding), bidirectional energizing pulses P1 to P8 every 90° shown in FIG. 4E are formed. This energization pulse turns on/off the transistors 11 to 18 in FIG.
In the section, switching energization is performed so that the polarity of the magnetic pole corresponds to the direction of energization, and rotational torque in one direction is generated.

Note that when the rotor magnet 21 is stationary, no induced voltage is generated from the coil, so at startup, the startup pulse generation circuit 6 generates a startup pulse for a certain period of time under the control of the microprocessor 7. The starting pulse is applied to the set and reset terminals of the flip-flop 3.4, and a two-phase pulse similar to the pulse signal in the fourth diagram) (a s Hb) is formed. The rotor magnet 2 is separately excited and driven.
1 is forcibly rotated in a predetermined rotation direction.

Next, FIG. 5 is a block circuit diagram showing an embodiment of the delay circuit 5 and mask circuit 8 of FIG. 1, and FIG. 6 is a waveform diagram of each part. The induced voltages E a SE b of the coils La and Lb are supplied to comparators 19 and 20 also shown in FIG. 2, and subjected to zero-cross shaping.

Each comparator 19.20 has a rising edge and a falling edge as Ea,
Pulse signals S1 and S2 (Fig. 6) corresponding to the zero crossing of Eb are formed, but spike-like induction noise occurs at the current switching positions (45°, 135°, 225°, 315°) of the coils La and Lb. N is detected. Therefore, the noise pulse Pn mixed into the pulse signals S1 and S2 is removed by the mask circuit 8.

The outputs S1 and S2 of the comparators 19 and 20 rise,
Falling edge detection circuit Bll, B12, B21, B2
2, and rising and falling edge pulses are individually derived as shown in FIGS. 83-S6. Each edge pulse S3 to S6 is an AND gate Gll for a mask;
Supplied to G12, G21, G22, FIG. 6 87-S1
An edge pulse like 0 from which the noise pulse Pn has been removed is obtained. Each edge pulse is paired with Noah gate G13, G
14, G23, and G24 to form pulse signals shown in FIG. 6, 311 and 312. This pulse signal is a pulse obtained by removing the noise pulse Pn from the pulse signals S1 and S2 obtained by zero-cross shaping the induced voltage.

The pulse signals Sll, S12 are led out to the flip-flop 3.4 as also shown in FIG. 1, and delayed pulse signals 313.514 (Ha, HB in FIG. 6) are formed as described above.

On the other hand, the output S of AND gates 011 to S22 for masking
7 to 310 are supplied to the OR gate G31, and S
A two-phase combined edge (leading edge, trailing edge) pulse shown at 16 is formed. This pulse S16 is supplied as a load pulse to the terminal LD of the delay counter 26 constituting the delay circuit 5. The load input of this counter 26 receives control data D0 to Dn corresponding to the rotational speed of the motor from the data bus 28 of the microprocessor 7 to the latch circuit 27.
Supplied via. Therefore, the counter 26 counts the daytime clock of a predetermined frequency supplied from the OR gate G33 from the time of the load pulse 316 based on the load data, and counts the nth day clock after the time T as shown in FIG. 6 S17.
Generates the output (rising edge) of the bit (MSB).

The position of the load pulse S16 corresponds to electrical angles of 0° and 180°. The time T expands and contracts depending on the load data from the data bus 28, and is always an electrical angle O regardless of changes in the rotational speed of the motor.

It is controlled to correspond to a 90" width of ~45° and 180° to 225°. That is, the time T increases at low speeds and contracts at high speeds.

After the MSB of the counter 26 rises to a high level, the output of the OR gate G33 becomes a high level at the high level output S17, and the clock input of the counter 26 is suppressed.

Therefore, as shown in FIG. 6 817, the next load pulse S1
S17 remains at a high level until 6 is supplied to the counter 26 and the MSB output falls. This counter output S
Reference numeral 17 is applied to the clock input of the flip-flop 3.4 as the delayed clock DCK shown in FIG. 4, and delayed pulse signals Ha, . . . Hb are formed as described above.

Further, the MSB output 317 of the counter 26 is also applied to the rising edge detection circuit 25, and a rising edge pulse shown at 318 in FIG. 6 is formed. This edge pulse 318 has electrical angles of 45°, 135°, 225°, and 315° for each phase in order.
represents the position of Next, in the OR gate G32, an OR output 319 of this edge pulse 518 and the output pulse S16 (0°, 180'') of the OR gate G31 is formed.The interval of this signal S19 expands and contracts according to the delay time width T, and its phase angle (electrical angle) is always constant (
0°, 45°, 135°, 180″, 225°, 315
°).

This OR output S19 is applied as a load pulse to the input LD of the mask counter 29 constituting the mask circuit 8. Like the delay counter 26 described above, this counter 29 takes in control data corresponding to the motor rotation speed from the data bus 28 of the microcomputer 7 via the latch circuit 30, and receives control data of a predetermined frequency supplied to the input CK from the OR gate G34. Count masked ivy. Therefore, as shown in FIG. 6 315, the counter 29 detects the low-level mask pulse that falls at each position of O'', 180°, 45°, 135°, and 315° indicated by the pulse S19, and rises after a predetermined period of time. It starts from.

Note that after the MSB (S15) rises to a high level, the mask clock is suppressed by the OR gate 34, and counting is stopped until the next load pulse is supplied.

Note that the mask width t described above is variable depending on the rotational speed of the motor, but may be a fixed value unrelated to the rotational speed.

The mask pulse S15 is applied to the seventh mask gate S11.
312.521, is supplied to S22, and the gate is closed in the low level section t. Therefore, as shown in the induced voltage waveforms Ea and Eb in FIG.
80°), 45°, 135°, 22°
The predetermined sections immediately after the current switching timings of 5° and 315° are masked.

Therefore, fine noise is added to the induced voltages Ea and Eb near the zero cross, and this causes the comparator 19.
Even if the outputs S1 and S2 of 20 fluctuate, S1 mask S2
Once the rising edge of is detected, changes immediately after that are ignored by the mask. Therefore, pulses Sll and S12 of the correct period can be obtained in which the positive half-wave and negative half-wave of the induced voltage correspond to high and low levels, respectively. Similarly, the spike-like noise that occurs when the current is switched to each coil is also removed by the mask immediately after the current is switched, so 0°, 18
It does not interfere with 0° detection. Therefore, by accurate Oo and 180° detection, the switching timing can be accurately determined using the digital delay described above.

As shown in FIG. 1, the zero-crossing detection pulses S11 and S12 from which interfering noise has been removed by the mask circuit 8 are also supplied to the microprocessor 7, and the rotational speed of the motor is detected by detecting their period. The control data formed by this speed detection is 0°~45° and 18°.
The signal is output to the data bus 28 in order to determine the delay time T and mask width t for each 90° from 0° to 225°. As mentioned above, the pulse S11 of the correct period is transmitted through the mask circuit 8.
, S12, the speed detection is very accurate. Note that speed detection may be performed using a frequency generator or a pulse generator attached to the motor.

Although an embodiment in which the present invention is applied to a two-phase bidirectional current-carrying type sensorless brushless motor has been shown above, the present invention can also be applied to a two-phase or more three-phase, four-phase, etc. unidirectional or bidirectional current-carrying type sensorless brushless motor. is possible.

〔Effect of the invention〕

As described above, in the present invention, the energization switching position is determined by a delay amount depending on the motor speed, so even if the rotor rotational position is detected based on the induced voltage of the excitation coil without a sensor, it is independent of the speed. It is possible to automatically control the energization switching position so that it is performed at a specific electrical angle. Therefore, even when the motor is started, the same energization switching as in the brushless morph with a rotor position sensor is possible. In addition, even if spike noise during energization switching, which is included in the induced electromotive force of the excitation coil, mixes into the position detection signal, it can be distinguished from the normal reference position and removed (masked), preventing malfunctions during energization switching. As a result, stable operation equivalent to sensor type brushless smoke can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a drive circuit diagram of the sensorless brushless motor of the present invention, FIG. 2 is a detailed diagram of the switching circuit of FIG. 1, FIGS. 3A and B are plan views of the rotor and stator of the brushless morph, and FIG. FIG. 1 is a waveform diagram of each part showing the operation, FIG. 5 is a detailed diagram showing the delay circuit and mask circuit of FIG. 1,
FIG. 6 is a waveform diagram of each part of the fifth part. In addition, in the symbols used in the drawings, 1-・-・−・−・・・・Switching circuit 2-
−−−−−・−−−1−・−・−・Drive pulse generation logic 3.4− ・−−−−−−−・D flip-flop 5−・−・−・−・−− −−−−−・−Delay circuit 6−−−1−・−−−−1−−−−・−Starting pulse generation circuit 7−−−−−−−−−−−−−−−−−− −Microprocessor 8・---−1−−−−−・−・・−・−・
Mask circuit 19.20--Comparator 2
t--・--・-- Rotor magnet 26・
・−−−−−−・−・−〜−−−−−−Delay counter 27・・−−−−−−・−・・−−−−−Latch circuit 28・−・−・−・−・----- Data buses La, Lb, --- Coils.

Claims (1)

[Claims] A circuit for detecting a reference position of rotor rotation based on the induced voltage of an excitation coil; a delay circuit for forming a delay pulse delayed by a predetermined amount from the reference position; A circuit that generates an energization switching signal for the excitation coil, a circuit that detects the rotation speed of the motor, controls the delay amount of the delay circuit, and adjusts the energization switching position according to the motor speed, and a circuit that detects the motor rotation speed and adjusts the energization switching position according to the motor speed. and a circuit for forming a mask signal for suppressing spurious pulses in the detection output of the reference position.