JPH06153580A - Method and apparatus for sensorless drive of three-phase brushless synchronous motor - Google Patents

Abstract

PURPOSE:To detect a commutation position on the basis of an induced voltage induced in each phase and to abolish the sensor which detects the position of a rotor in a three-phase brushless synchronous motor. CONSTITUTION:A three-phase brushless synchronous motor is constituted to be driven in such a way that square waves at a prescribed electricity-feeding angle are applied to a three-phase brushless synchronous motor 1 from a driving device 3. The three-phase brushless synchronous motor is constituted of an OR-circuit 8 which outputs a pulse whenever an induced voltage in each phase is zero-crossed of a differentiation circuit 6 which shifts the phase of the induced voltage in each phase, and of a pulse formation circuit which forms a pulse used to output the square waves at the prescribed electricity-feeding angle from a three-phase bridge circuit on the basis of an induced voltage waveform, an output waveform output by the differentiation circuit 6 and a timing signal output by the OR-circuit at a timing of zero-crossing point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates a rotor position detector used for avoiding a step-out phenomenon peculiar to a three-phase brushless synchronous motor, in particular, a synchronous motor, and avoids step-out by a new detection method instead. The present invention relates to a sensorless driving method and a device thereof for a three-phase brushless synchronous motor made possible.

[0002]

2. Description of the Related Art A method of driving a three-phase synchronous motor has been used for a long time. As an example, a synchronous operation is performed by increasing a load inertia moment of a motor and gradually increasing a power supply frequency so as not to get out of step at the time of starting. It was made possible, and when the load fluctuates suddenly, the energy released from the moment of inertia of the load makes it difficult to get out of step.

Recently, however, attention has been paid to the high efficiency of synchronous motors, and brushless three-phase synchronous motors have been re-examined for their ease of maintenance and are used in fields requiring high speed and high response, such as factory automation. It has been used for various purposes such as a servo motor or a control motor. In order to use for such an application, it is necessary to keep the load moment of inertia as small as possible and attach importance to its responsiveness, and it is necessary to solve the step-out phenomenon peculiar to the synchronous motor.

A general method for solving the problem is to use a rotor position detector for detecting the position of the rotor of the synchronous motor, and a so-called rotary energization for synchronous energization by a detection signal from the rotor position detector is used. This is a flow control method.

FIG. 4 shows a three-phase brushless synchronous motor 120.
The figure illustrates the waveforms related to the energization method. The phase induced voltage of each phase voltage U, V, W and the phase relationship of the energized current to each of these phases are always the same, and the induced voltage of the phase voltage is zero. 30 ° before and after the point (crossing 0 V) is the energization pause period, and each phase is energized at 120 ° so as to be in phase with the induced voltage except for this energization pause period. These power-off periods are obtained by detecting the rotor position using a rotor position detector provided on the motor shaft, for example, a sensor such as a Hall element, a resolver, or an encoder.

At present, by using such a sensor, it has become possible to use a three-phase brushless synchronous motor which is highly responsive, stable to load fluctuations, and highly efficient without step-out.

[0007]

However, since the motor has a sensor, its use may be restricted depending on the environment of use of the motor. For example, in an environment such as high humidity, extremely low temperature, or gas atmosphere. May deteriorate the performance of the sensor and prevent its use.

The present invention has been made in view of the above points, and the three-phase brushless synchronous motor in which the above-mentioned sensor is eliminated and stable control is possible in a wide range of speed and torque without step-out. It is an object of the present invention to provide a sensorless driving method and device thereof.

[0009]

To achieve the above object, a sensorless driving method for a three-phase brushless synchronous motor according to the present invention drives a motor by applying a rectangular wave having a predetermined conduction angle via an inverter. In the three-phase brushless synchronous motor having the configuration, the zero cross of the induced voltage induced in each phase is detected for each phase, and the rectangular wave having the predetermined conduction angle is generated based on the detection time of the zero cross. The feature is that the commutation position is detected by adopting a configuration in which the voltage is applied to the inverter.

The sensorless drive system for a three-phase brushless synchronous motor according to the present invention is a three-phase brushless synchronous motor configured to drive a motor by applying a rectangular wave having a predetermined conduction angle through an inverter. A zero-cross detection circuit that detects a zero-cross voltage, a phase shifter that shifts the phase of the induced voltage of each phase, an induced voltage waveform, an output waveform of the phase shifter, and a zero detected by the zero-cross detection circuit. A commutation position is detected by providing a pulse creating circuit for each phase for generating a pulse for outputting the rectangular wave having the predetermined conduction angle from the inverter from the time of crossing. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of a commutation detection circuit used in the present invention. In the figure, 1 is a three-phase brushless synchronous motor, 2 is a commutation detection circuit, 3 is a drive device,
4 is a filter and amplifier, 5 is a comparator, 6 is a differentiating circuit, 7 is an edge pulse generating circuit, 8 is an OR circuit, 9 is a sample hold circuit, 10 is a voltage dividing circuit, 11 is a comparator, 12 and 13 are AND circuits, Reference numerals 14 and 15 represent inverter circuits, and 16 and 17 represent resistors.

In FIG. 1, the commutation detection circuit 2 for the U phase is shown, and the commutation detection circuit of the same configuration is used for the remaining V phase and W phase, but the illustration is omitted. Has been done. The U phase will be described below, but V
The same is true for the W and W phases.

The commutation detection circuit 2 detects the phase voltage induced in the U-phase winding of the three-phase brushless synchronous motor 1. Referring to the waveform diagram of FIG.
The phase voltage signal, that is, the U-phase induced voltage (A in FIG. 2) is input to the filter and the amplifier 4 and its high frequency component is removed (B in FIG. 2). It is determined (C in FIG. 2).

This positive polarity discrimination signal is input to the edge pulse generation circuit 7, pulses are generated at the rising edge and the falling edge of the positive polarity discrimination signal, respectively, and synthesized by the OR circuit 8 and output from the filter and amplifier 4. A pulse for detecting the zero crossing of the output U-phase voltage signal is output (D in FIG. 2). The zero-cross detection signal is used as the sampling timing signal of the sample hold circuit 9.

On the other hand, the U-phase voltage signal output from the filter and amplifier 4 has a differentiating circuit 6 that advances its phase by 90 °.
The U-phase voltage signal (E in FIG. 2) whose phase is advanced by 90 ° is input to the sample hold circuit 9 and is sampled and held by the sampling timing signal from the OR circuit 8 (F in FIG. 2). . The sample-held signal indicated by F in FIG. 2 is input to the voltage dividing circuit 10,
The voltage of √3 / 2 times, that is, c
The voltage is divided into a voltage ratio for obtaining an angle corresponding to os30 °, and is input as a reference voltage to the non-inverting input terminal of the comparator 11. Since the U-phase voltage signal advanced by 90 ° from the differentiating circuit 6 is input to the inverting input terminal of the comparator 11, it is √3 / 2 times the sample-and-hold signal divided by the voltage dividing circuit 10. When the U-phase voltage signal advanced by 90 ° from the reference voltage of is smaller than H
A level signal is output (G in FIG. 2). Therefore, the G signal of FIG. 2 output from the comparator 11 has a pulse waveform whose phase is delayed by 30 ° from the zero cross point of the positive waveform of the U-phase voltage signal obtained from the filter and amplifier 4.

The signal of G in FIG. 2 thus obtained is passed through the output signal obtained from the comparator 5 and the logic circuits of the inverter circuits 14 and 15 and the AND circuits 12 and 13 to obtain the AND circuits 12 and 13. Can obtain the waveform pulses L and M shown in H and I of FIG. The pulses L and M serve as commutation detection signals for rotating the three-phase brushless synchronous motor as described below.

FIG. 3 shows the configuration of a specific embodiment of the present invention, and the reference numerals 1, 2, 12, and 13 correspond to those of FIG. Reference numeral 21 is a three-phase bridge circuit, 22 is a base drive circuit, 23 is an auxiliary drive pulse generator, 24 to 29 are OR circuits, 30 to 35 are AND circuits, and 36 to 41 are inverter circuits.

The input signals of the U-phase, V-phase, and W-phase commutation detection circuits 2 are the terminals U, V, and V of the three-phase brushless synchronous motor 1.
Get each from W. The output signals of the U-phase, V-phase, and W-phase commutation detection circuits 2 enter the base drive circuit 22 via the AND circuits 30 to 35 and the inverter circuits 36 to 41, and the OR circuits 24 to 29. ,
It becomes the base drive signal of the three-phase bridge circuit 21. That is, the three-phase brushless synchronous motor 1 has the U shown in FIG.
1 for each phase at the same timing as each phase, V phase, W phase current
Electric power having each of the 20 ° energization period and the 60 ° rest period is supplied from the three-phase bridge circuit 21.

A PWM signal is applied to each of the AND circuits 30 to 35, and the electric power supplied to the three-phase brushless synchronous motor 1 is changed by controlling the energizing pulse width by the PWM signal. It controls the number of rotations.

The change in the commutation position due to the change in rotation at this time is detected by the commutation detection circuit 2 for each phase, which enables stable and highly efficient control without step out in a wide range.

In this system, since the rotation of the three-phase brushless synchronous motor 1 rises to a certain degree and the commutation detection circuit 2 needs to generate an induced voltage that can detect and capture the commutation, the low rotation speed range , The gain of the filter and amplifier 4 shown in FIG. 1 is increased. In the high rotation speed range, the gain is reduced to stabilize the detection accuracy. Further, at the time of start-up, since the induced voltage is not generated and the commutation position cannot be detected, the auxiliary drive pulse generator 23 is provided, and the auxiliary drive pulse generator 23 is used for the low-speed synchronization of the three-phase brushless synchronous motor 1. When the rotation is obtained and the commutation detection circuit 2 can detect the commutation position, the output of the auxiliary drive pulse generator 23 is stopped.

The configuration of the commutation detection circuit 2 shown in FIG. 1 is only an example, and it goes without saying that it may be configured by other circuits. In the above description, the conduction angle is 120
However, the present invention is also applicable to a three-phase brushless synchronous motor having an energization angle other than 120 °, for example, 150 ° and 180 °.

[0023]

As described above, according to the present invention, the commutation position of the three-phase brushless synchronous motor can be correctly detected, and the three-phase brushless synchronous motor is energized with a rectangular wave having a predetermined energization angle. You can Therefore, a rotation detecting sensor such as a hall element for detecting rotation, a resolver, and an encoder is not required, and the three-phase brushless synchronous motor can be stably controlled without step-out even in a bad environment.

[Brief description of drawings]

FIG. 1 is a configuration of an embodiment of a commutation detection circuit used in the present invention.

FIG. 2 is an operation waveform diagram of FIG.

FIG. 3 is a configuration of a specific example of the present invention.

FIG. 4 is a waveform explanatory diagram related to a 120 ° energization method of a three-phase brushless synchronous motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 three-phase brushless synchronous motor 2 commutation detection circuit 3 driving device 4 filter and amplifier 5 comparator 6 differentiating circuit 9 sample hold circuit 10 voltage dividing circuit 21 three-phase bridge circuit 22 base drive circuit 23 auxiliary drive pulse generator

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[Procedure amendment]

[Submission date] December 14, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In FIG. 1, the commutation detection circuit 2 for the U phase is shown, and the commutation detection circuit of the same configuration is used for the remaining V phase and W phase, but the illustration is omitted. Has been done. The U phase will be described below, but V
The same holds true for the W and W phases. Three-phase
The diagram of the neutral point of the brushless synchronous motor 1 is grounded.
In the three-phase brushless synchronous motor 1 shown
Since the sex point can be regarded as 0 V in appearance, it is neutral.
You may leave the dots floating without dropping them to earth.

Claims (2)

[Claims] 1. A three-phase brushless synchronous motor configured to drive a motor by applying a rectangular wave having a predetermined conduction angle via an inverter, and detects a zero cross of an induced voltage induced in each phase for each phase. At the same time, the three-phase brushless synchronization is characterized in that the rectangular wave having the above-mentioned predetermined conduction angle is generated based on the detection time point of the zero cross and is applied to the inverter, and the commutation position is detected. A sensorless driving method for an electric motor. 2. A three-phase brushless synchronous motor configured to drive a motor by applying a rectangular wave of a predetermined conduction angle via an inverter, and a zero-cross detection circuit for detecting a zero-cross of the induced voltage of each phase, From the phase shifter that shifts the phase of the induced voltage of each phase, the induced voltage waveform, the output waveform of the phase shifter, and the zero-cross time point detected by the zero-cross detection circuit, the rectangular wave of the predetermined conduction angle is generated. A sensorless drive device for a three-phase brushless synchronous motor, characterized in that a pulse generation circuit for generating a pulse to be output from the inverter is provided for each phase to detect a commutation position.