JP2002281780A - Electric motor driving system and electric motor controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that, though position sensors are usually mounted on a stator, distortion of detected waveforms occurs in such cases as when their shape, structural restrictions and the like result in poor mounting accuracy of not being arranged every 120 degrees or when position cannot be detected so that is leads to hunting of number of revolutions, deterioration of efficiency, overcurrent breaking by current increase and the like, and to the inability of securing stable operations. SOLUTION: This driving system is provided with 'n' pieces ('n': an integer of 1 or larger) of position detectors that output position signals having a certain positional relation to an induced voltage of a synchronous motor; a position signal change-over means that changes the number of the position signals to be used by selecting position signals to be used in accordance with operating conditions of the 'n' pieces of positional signals that are outputted from the 'n' pieces of position detectors; and an electric motor diver that impresses a voltage to the windings of the synchronous motor to drive it based on a waveform forming means that forms conducting waveforms of the synchronous motor from the positional signals selected by the position signal change-over means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive system and a motor control method capable of operating stably and efficiently over a wide range.

[0002]

2. Description of the Related Art In recent years, synchronous motors have become the mainstream of conventional induction motors for fan motors of air conditioners and the like, and motors for driving washing machines, for variable speed control and energy saving over a wide range. Therefore, the ratio of driving these electric motors by inverter control is increasing.

FIG. 14 is a schematic diagram showing a configuration of a drive circuit of a conventional synchronous motor. In the figure, reference numeral 30 denotes a synchronous motor, which includes a stator 6 and a rotor 7. 20 is a position sensor, 1 is a power supply, 4 is a converter, 5 is an inverter device, and 31 is control means. Inside the synchronous motor 30 having three-phase windings, a Hall IC having a simple structure and an inexpensive position is usually used as the position sensor 20. For example, three or two Hall ICs are arranged every 120 electrical degrees. I have. Then, a position signal corresponding to the rotational position of the rotor 7 is input to the control means 31 by these Hall ICs. The control unit 31 drives the inverter 5 by forming an energization waveform based on the position signal and applying a voltage to the winding of the synchronous motor 30 to drive the synchronous motor.

Conventionally, for example, as shown in FIG.
When three position sensors are arranged, all three position signals of the three position sensors 20 are used, a three-phase rectangular wave signal is formed from the three position signals, and the rectangular wave driving is performed. The control means 31 starts the operation and thereafter switches to a substantially sinusoidal energization. The control means 31 determines the energization waveform without switching the number of signals of the position sensor to be used depending on the operation state. For example, the number of position signals of the position sensor used during low-speed rotation and high-speed rotation is not switched, and the energization waveform is determined using the number of position signals of the position sensor of the position detection unit 20 used first as it is. are doing. For example, Japanese Patent Application Laid-Open No.
No. 0 and JP-A-59-136058.

[0005]

A Hall IC is used as a position sensor 20 of a synchronous motor having three-phase windings.
For example, in a case where three position sensors 20 are arranged for every 120 electrical degrees, since the three output signals of the position sensors of the three position detecting means 20 are used, the magnetization of the rotor 7 is performed. If the position signal of each phase is not output every 120 degrees in electrical angle due to state variation, the detected waveform will be distorted, causing hunting of the rotation speed, reduction of efficiency,
Stable operation was not possible due to overcurrent interruption due to an increase in current, and reliability was reduced.

Further, since a Hall IC is used as the position sensor 20, as shown in FIG. 15, the leakage magnetic flux increases in accordance with the rotation speed. FIG. 15 is a diagram illustrating the relationship between the rotation speed and the leakage magnetic flux when a Hall IC is used. In the figure, the horizontal axis represents the rotation speed, and the vertical axis represents the leakage magnetic flux (φ). As shown in the figure, the leakage magnetic flux of the Hall IC increases in the high rotation range where the rotation speed increases, and the leakage magnetic flux (φ)
Increases, the detection error (the amount of deviation between the actual position of the rotor and the detected position) also increases, and there is a problem that the accurate position of the rotor 7 cannot be detected.

Further, the position sensor is usually mounted on the stator 6, but the position sensor 20 is not fixed due to restrictions on its shape and structure, or restrictions on the mounting accuracy and mounting position of the machine for mounting the position sensor. If the mounting accuracy is poor and the arrangement is not every 120 degrees, or if it cannot be arranged in a position or direction where the position can be detected with high accuracy, the detected waveform will be distorted, resulting in hunting of the rotation speed, reduction in efficiency, and an increase in current. Stable operation could not be achieved due to overcurrent interruption, etc., which was a problem.

Further, when the position sensorless control is performed without providing a position sensor, it takes a long time to start, and in a low-speed region, the induced voltage is small. It was not possible to judge, it was difficult to detect step-out, and stable operation was not possible.

Further, as shown in FIG. 16, at the time of acceleration or load fluctuation, there is a problem that the phase deviates from the optimum value and current and loss increase. FIG. 16 is a diagram showing the relationship between the motor rotation speed and the current. The horizontal axis represents the rotation frequency, and the vertical axis represents the current I. As shown in the figure, at a certain rotational speed NA, the current value is small (I0) at the point of the optimal phase angle (marked by ● in the figure) and the efficiency is good, but when it is deviated from it (for example, mark Δ in the figure). The current value was large (I1) and the loss was also increasing.

In the conventional synchronous motor drive system, when the phase difference between the voltage and current of the stator winding deviates from the optimum phase angle, increasing the voltage to achieve the target rotation speed increases the current, resulting in a loss. In some cases, the rotation speed cannot be increased to the target rotation speed due to an increase or a decrease in efficiency or a lack of torque.

In this case, even if the voltage is increased to increase the rotation speed, only the current increases without increasing the rotation speed, and the overcurrent stops and the current increases, or the current increases to near the demagnetization level. As a result, the rotor magnetic flux φ is demagnetized, and stable operation cannot be ensured, leading to a decrease in reliability. For example, when applied to a fan motor, when the fan is installed at low temperature and the air density is high, or when the fan is given a torque in the reverse rotation direction such as in the case of a head wind, or If the Hall IC is displaced in the position detection signal due to the influence of the leakage magnetic flux of the stator 6, the rotational torque becomes smaller than the load torque, and the fan motor cannot be accelerated and stable operation cannot be performed. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a highly reliable motor drive system and a method for controlling a motor. It is another object of the present invention to provide a motor drive system and a motor control method capable of performing stable and accurate motor control. Another object is to reduce the number of position sensors to be used or the number of position signals to be used. It is another object of the present invention to obtain a low-cost motor drive system and a method for controlling a motor. It is another object of the present invention to reduce the size of the sensor arrangement board and the size of the motor drive system.

It is another object of the present invention to provide a motor drive system and a motor control method capable of efficiently and stably operating in a wide operating range. It is another object of the present invention to provide an electric motor drive system in which a rotor position detection error is small and an accurate rotor position can be detected.

It is another object of the present invention to provide a position sensorless control capable of accurately detecting a rotational position even in a low speed range and enabling a step-out determination. It is another object of the present invention to provide an electric motor drive system and an electric motor control method capable of increasing the number of revolutions to a target value.

It is another object of the present invention to prevent an overcurrent from stopping due to an increase in current even when only the current continues to increase without increasing the rotation speed. It is another object of the present invention to prevent a rotor magnetic flux from being demagnetized due to an increase in current near a demagnetization level.

[0016]

The motor drive system according to the first aspect of the present invention outputs a position signal having a fixed phase relationship with respect to an induced voltage generated by a winding of a synchronous motor. : 1 or more integer position detecting means, and n
Position signal switching means for changing the number of position signals to be used by selecting a position signal to be used in accordance with the operation state from the n position signals output by the position detection means; Energizing waveform forming means for forming an energizing waveform of the synchronous motor based on the selected position signal; and applying a voltage to the winding of the synchronous motor based on the energizing waveform formed by the energizing waveform forming means to control the synchronous motor. Electric motor driving means for driving.

A motor drive system according to a second aspect of the present invention is configured to switch the number of position signals to be used according to the number of rotations of a synchronous motor.

The motor drive system according to the third aspect of the present invention uses n position signals at least at the time of startup or low-speed rotation, and uses less than n position signals at other rotation speeds. It was done.

A motor drive system according to a fourth aspect of the present invention is a motor drive system for detecting the number of rotations of a synchronous motor based on a position signal from a position detector, and a synchronous motor for the position signal. Phase changing means for changing the phase difference of the applied voltage with respect to the position signal by grasping the phase difference of the applied voltage and adjusting the phase difference by a predetermined value; and based on the applied voltage changed by the phase changing means and its phase. An energization waveform forming means for forming an energization waveform for driving the synchronous motor; and changing a phase of a voltage applied when the number of rotations detected by the number of rotations detection means is out of a target number of rotations. Thus, the target rotation speed is obtained.

The motor drive system according to a fifth aspect of the present invention uses, as the position detecting means, a position sensor for detecting the rotor position of the synchronous motor or a current detecting means for detecting a current flowing through the winding of the synchronous motor. It is intended to be.

A motor drive system according to a sixth aspect of the present invention outputs n (n) position signals of different phases each having a fixed phase relationship with respect to an induced voltage generated by a winding of a three-phase synchronous motor. = 1, 2, 3) position detecting means.

According to a seventh aspect of the present invention, there is provided a motor drive system comprising: a rotation speed detecting means for detecting a rotation speed of a synchronous motor; a voltage storage means for storing a change ratio of a voltage value applied to the synchronous motor; A number-of-revolutions storage means for storing the rate of change of the number of revolutions detected by the number-of-revolutions detection means; Phase angle control means for calculating and changing the phase angle of the applied voltage applied to the synchronous motor by a predetermined amount according to the change rate.

According to an eighth aspect of the present invention, there is provided an electric motor drive system comprising: a rotational speed detecting means for detecting a rotational speed of a synchronous motor; a voltage storing means for storing a change ratio of a voltage value applied to the synchronous motor; A number-of-revolutions storage means for storing a rate of change of the number of revolutions detected by the number-of-revolutions detection means; Rotation speed determining means for changing the target rotation speed.

According to a ninth aspect of the present invention, there is provided a motor control method for detecting an induced voltage generated in a synchronous motor or a position signal having a fixed phase relationship with an induced voltage generated in a winding of the synchronous motor. Then, a phase angle of the applied voltage with respect to the induced voltage or the position signal is compared with a target phase angle stored in advance corresponding to the rotation speed, and a voltage applied so that the phase angle of the applied voltage becomes the target phase angle. A phase changing step of changing the phase angle of the phase and outputting phase information; an energizing waveform forming step of forming an energizing waveform for driving the synchronous motor based on the phase information obtained from the phase changing step; A motor driving step of driving the synchronous motor by applying a voltage to the winding of the synchronous motor based on the conduction waveform formed by the step.

A motor control method according to a tenth aspect of the present invention includes a rotation speed detection step for detecting a rotation speed of the synchronous motor, and the actual rotation speed detected in the rotation speed detection step is set to a target rotation speed. In this case, the voltage value or the phase angle of the applied voltage is changed in such a manner.

According to an eleventh aspect of the present invention, there is provided a method for controlling a motor, comprising: a rotation speed storing step of storing a change ratio of a rotation speed of the synchronous motor; and a voltage storing a change ratio of an applied voltage applied to the synchronous motor. The storage step and the change rate of the rotation speed obtained from the rotation number storage step and the change rate of the applied voltage obtained from the voltage storage step are respectively compared with predetermined values to change the phase angle of the applied voltage or to change the target rotation. A step of changing the number of rotations and an energization waveform for changing the rotation speed of the synchronous motor based on the information on the phase angle of the applied voltage or the information on the target rotation speed changed in the comparison change step. A voltage is applied to the winding of the synchronous motor based on the current waveform formed in the current waveform forming step and the current waveform formed in the current waveform forming step. A motor driving step of moving, in which with a.

In the motor control method according to the twelfth aspect of the present invention, n (n: n) having a fixed phase relationship with respect to an induced voltage generated in the synchronous motor or an induced voltage generated in the winding of the synchronous motor. A position signal detecting step of detecting (integral number of 1 or more) position signals, and a position to be used by selecting a position signal to be used in accordance with the operation state from the n position signals detected by the position signal detecting step. And a position signal switching step of changing the number of signals.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing a synchronous motor drive system according to a first embodiment of the present invention. In the figure, reference numeral 1 denotes a power source, 4 denotes a converter, and 30 denotes a motor, which is constituted by a stator 6 and a rotor 7. . Reference numeral 2 denotes a position detecting means, for example, using a position sensor (such as a Hall IC), which outputs a position signal synchronized with an induced voltage signal corresponding to the rotational position of the rotor 7. Here, it is preferable to drive the motor by applying a voltage to the winding of the synchronous motor at an energization timing based on an induced voltage generated in the winding of the synchronous motor. When the position signal to be synchronized is synchronized with the induced voltage signal, in the present embodiment, the position signal of the position detecting means 2 is used instead of directly detecting the induced voltage. Reference numeral 3 denotes control means for outputting an energization signal for driving the electric motor based on the position signal output from the position detection means 2. Reference numeral 5 denotes a winding of the stator 6 at an energization timing based on the energization signal from the control means 3. Voltage to the motor 30
Is an inverter that drives.

When a position sensor is provided as the position detecting means 2 for detecting the position of the rotor, generally in the case of three phases, a total of three position sensors are arranged, one for each phase. In the present invention, the number is not limited to three but may be plural in one phase. In addition, it is not necessary to dispose them in all three phases, and two or one phase may be used. Therefore, the number of the position detecting means 2 may be n (n is an integer of 1 or more), and a plurality of the position detecting means 2 may be arranged in one phase. In the case of three phases, it is not necessary to use more than three pieces, and three or less than three pieces may be used, or two or one pieces. The smaller the number, the lower the cost.

Also, by reducing the number of position sensors of the position detecting means 2 to less than three and to two or one, there is a space for the structure, and the mounting of the position sensor is less likely to be restricted by the structure. The position can be detected well. Reference numeral 10 denotes a current detecting means, and the motor 3
It detects the current flowing through the zero winding, and may be provided only when necessary. Further, the phase need not be three, and may be a single phase or three or more phases.

Here, the control means 3 will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a configuration of a control unit according to the first embodiment of the present invention. In the figure,
101 is a rotation number detecting means for detecting the position of the rotor 7 and the rotation frequency (rotation number) of the electric motor 30 based on the position signal of the position sensor of the position detection means 2, and 102 is used according to the rotation frequency (rotation number). This is a position signal switching unit that switches the number of signals of the position sensor to be switched. 103 is a rotation speed command means for outputting a target rotation speed; 104 is a voltage for outputting an applied voltage value and a phase necessary for the detected rotation speed to become the target rotation speed by comparing the target rotation speed and the detected rotation speed. It is a phase determining means. Reference numeral 105 denotes a conduction waveform forming unit that generates a conduction waveform so that the inverter 5 can actually output the voltage value and phase determined by the voltage / phase determination unit to the synchronous motor 30 and outputs the generated waveform to the inverter 5.

Next, the operation will be described. When the position detecting means 2 outputs a position signal synchronized with the induced voltage corresponding to the rotational position of the rotor 7, the control means 3 supplies power for driving the electric motor 30 based on the position signal of the position detecting means 2. Outputs a waveform (energization signal). As a result, the inverter device 5 that drives the motor applies a voltage to the winding of the stator 6 at the energization timing output by the control device 3 to drive the motor.

That is, the position signal of the position detecting means 2 is output to the rotational speed detecting means 101 in the control means 3. Further, the rotation number detecting means 101 calculates a rotation frequency (number of rotations) based on the position signal of the position detecting means 2 and outputs it to the position signal switching means 102. Position signal switching means 10
The number 2 selects and switches the number of position signals to be used according to a preset rotation speed. Here, if, for example, three position sensors are arranged as the position detecting means 2, at the time of startup, all three position signals of the position sensors are used, and the number of rotations increases and the number of rotations set in advance (for example, In the case of a constant-speed rotation speed region or a high-speed rotation speed region), control is performed such that only two position signals with good position accuracy (or one position signal) are selected and the number of position signals to be used is switched. . Thereafter, as the position signal to be used, a position signal with good position accuracy after switching is used. However, when the rotation speed changes to the set rotation speed, the position signal to be used is selected again and the position signal is selected. Change the number of signals.

The voltage / phase determining means 104 compares the target rotation speed given by the rotation speed command means 103 with the detection rotation speed detected by the rotation speed detection means 101, and determines the detected rotation speed as the target rotation speed. And outputs the applied voltage value and its phase required to become. The energization waveform forming means 105 forms an energization waveform such that the inverter 5 can drive the synchronous motor 30 with the applied voltage value output from the voltage / phase determination means 104 and its phase. The inverter 5 drives the synchronous motor 30 while applying a voltage to the windings of the stator 6 of the synchronous motor 30 to control the number of revolutions according to the conduction waveform formed by the conduction waveform forming means 105.

Here, the number of the position detecting means 2 to be attached does not need to be three for three phases, but may be n (n is an integer of 1 or more), four, two, one. May be.
In the present invention, the number of position signals to be used is switched by selecting only position signals having good position accuracy according to the operation state (operation frequency, rotation speed, current, phase, etc.) of the n position detection means 2. Therefore, a stable operating state of the synchronous motor can be ensured unlike the related art. Here, if the number of attached position detecting means 2 is n, the number of position signals to be selected may be smaller than n.

Therefore, in an operating state where there is no problem even if the number of position signals is reduced, the position signal of the position detecting means 2, which has a large error with respect to the position sensor, such as a phase shift due to the mounting position or direction, or a detection error, and has low accuracy is used. By avoiding this, the phase shift due to the mounting position and direction of the position detecting means 2 or the position detecting means 2
Therefore, an error relating to the position detecting means 2 (for example, a position sensor such as a Hall IC) such as a detection error can be eliminated, and a highly reliable motor drive system that can be operated with high accuracy can be obtained.

Here, a method of selecting the position detecting means 2 in the position signal switching means 102 will be described. Usually, the accuracy of the position signal is determined by the mounting accuracy of the position detecting means 2, that is, the displacement of the mounting position or the direction, and it is sufficient to determine in advance which position signal to select. The position detecting means 2 is mounted on a board or the like to be actually used in the same state as the actual state, and it is detected in advance by inspection or the like whether or not there is a phase shift due to the mounting position and direction with respect to the position signals of all the position detecting means 2. In advance, it may be determined that a position signal other than the position detecting means 2 having a large phase shift due to the mounting position or direction is selected. In this case, the whole lot may be inspected to detect a large deviation in the mounting position and direction, but if the same lot, the deviation in the mounting position and direction is almost the same, so only the first lot is inspected. You may do it.

A method for automatically selecting the position signal of the position detecting means 2 during operation will be described. During operation, at a certain speed (rotational speed), the electric motor has a minimum current value if it is at the optimum phase angle. However, if the deviation of the position signal is large, it becomes impossible to control the motor so as to obtain the optimum phase angle. The current value increases. Therefore, a current detecting means is provided to detect a current (bus current) during operation, and to select a position signal that reduces the current when a voltage is applied based on the respective position signals. Just fine.
(A target current value corresponding to each rotation speed may be provided in advance, and a position signal that is equal to or less than the target current value may be selected.)

Next, a method for estimating the position signals of the remaining phases based on the position signals selected by the position signal switching means 102 will be described. Here, as an example, a case will be described in which three position detecting means 2 are attached to different phases in a three-phase synchronous motor. First, the waveforms of the position signals of the position signals for three different phases will be described with reference to FIG.

FIG. 3 shows three phase detectors when three position detectors 2 (for example, position sensors such as Hall ICs) are mounted, one for each phase, and three phase signals are output. FIG. 5 is a diagram illustrating an example of a position signal waveform of FIG. In the figure,
The horizontal axis represents time, and the vertical axis represents the conduction waveform of each phase (U, V, W phases). The numbers ~ in the figure each represent a 1/6 section of the electric cycle. That is, one section (for example) corresponds to 1/6 of the electric cycle. Generally, the rotation frequency of the rotor 7 is represented by (electric frequency) / (number of pole pairs of the rotor 7). Here, the number of pole pairs is 2 for a 4-pole motor and 1 for a 2-pole motor.

In the figure, the case of the U phase will be described as an example.
In the U-phase, at the end of the section, that is, at the beginning of the section, electricity is supplied and the energization waveform rises. Has become. Then, during the section, the power supply OFF state continues, and the power supply is turned ON again at the beginning of the section, and the power supply waveform rises. This has been repeated thereafter. In this case, one cycle is represented by (D). Similarly, energization ON / OFF is repeated for the V phase and the W phase. However, ON /
The OFF timing is shifted by two sections (2/6 cycle).

Here, a method of estimating the remaining one-phase position signal when two position signals having good position accuracy are selected by the position signal switching means 102 among the three position detection means 2 will be described. . In other words, when the number of rotations becomes equal to or more than the set number of rotations, when the number of position signals is selected from three to two with high accuracy by the position signal switching means 102, the remaining one phase signal from the two selected position signals is obtained. A method for estimating the position signal will be described.

For example, in FIG. 3, when detecting the U-phase and V-phase position signals and predicting the W-phase signal, the time (A) from the fall of the V-phase to the rise of the U-phase in the section is calculated. The time (A) is detected and stored.
Since the time point added to the rising point of the phase becomes the falling point of the W phase, the timing of the W phase can be determined.
At this time, the electric cycle of the W phase may be set to be six times the detected time (A).

Alternatively, the time (B) from the rise of the V phase to the fall of the U phase in the section of FIG. 3 is detected and stored, and the time when this time (B) is added to the fall time of the U phase is W As the phase rises, the timing of the rise of the W phase can be determined. Again,
The electrical phase of the W phase may be set to be six times the detected time (B).

Also, as shown in the section of FIG.
Time from phase rise to V phase rise (C)
Is detected and stored, and the time when this time (C) is added to the time when the V-phase rises becomes the rise of the W-phase, and the timing of the fall of the W-phase can also be determined. At this time, the predicted electrical phase of the W phase is 3 times the detected time (C).
Double.

Further, by setting the time point obtained by adding twice the time (C) to the time point when the U-phase rises to be the rise of the W-phase, the timing of the rise of the W-phase can be determined.

As described above, the two phases to be detected are not limited to the combination of the U and V phases, but may be, for example, a combination of the V phase and the W phase. The time (C) from the rise of the U-phase to the rise of the V-phase may be the time from the fall of the U-phase to the fall of the V-phase. Thus, the remaining one-phase position signal waveform can be predicted.

Next, a description will be given of a method of estimating the remaining two-phase position signals when one position signal having good position accuracy is selected by the position signal switching means 102 among the three position detection means 2. . For example, in FIG.
A case in which only the U-phase position signal is detected to predict the V-phase and W-phase signals will be described. In this case, the time (D) from the rise of the U phase to the rise of the U phase is detected and stored, and the time when 1/3 of this time (D) is added to the rise time of the U phase is the rise of the V phase. Therefore, the rising timing of the V phase can be determined. At this time, it is assumed that the predicted electrical phase of the V phase is equal to the detected time (D).

The time when 2/3 of the time (D) is added to the rising time of the U phase, or
The time when 1/3 of the time (D) is added to the rising time of the phase waveform becomes the rising of the W phase, and the timing of the rising of the W phase can be determined. Also at this time, the predicted electric cycle of the W phase is equal to the detected time (D).

In addition, the time from the rise to the fall of the U-phase, or the time from the fall to the rise of the U-phase, that is, 1/2 of the time (D) may be detected and used. That is, if １ ／ of the time (D) is multiplied by 2/3 or 4/3, as described above,
V-phase and W-phase position signals can be predicted.

The case where the U-phase signal is used has been described above, but the signal to be detected is not limited to the U-phase.
A V phase or a W phase may be used, and one phase having good detection accuracy may be selected.

During acceleration or deceleration, the position signal cycle fluctuates greatly. Therefore, in the case of FIG. 3, it is better to use the shorter time (A) or time (B) for the time (C) or time. Compared with the case of predicting the signal using (D), the position error signal of the other phase can be predicted with a small variation error and high accuracy.

Now that the method for estimating the position signal has been described, a description will be given next of what operating state the number of position signals is switched. In the present invention, the number of position signals is switched according to the operation state (for example, rotation speed, operation frequency, current, and the like).
The switching condition when the rotation speed is used as the operation state will be described.

When the position detecting means 2 is composed of n (n is an integer of 1 or more) position sensors, in the present embodiment, the speed is low at the time of startup, at the time of steady rotation, and even at the time of steady rotation. The number of position signals to be used is switched between during rotation and during high-speed rotation. That is, the number of position signals to be used is switched according to the operation state of the synchronous motor. Here, the start time represents a state during acceleration immediately after the start of operation, and is usually a rotation speed region within about several minutes. The low speed indicates a region where the induced voltage of the electric motor is small, and a low speed region where the induced voltage is too small in the ordinary position sensorless control and it is difficult to detect the step-out.

The term "high speed" means, for example, a region where the position sensor is used as the position detecting means 2 and a Hall IC is used as the position sensor, where the leakage flux of the position sensor becomes large. Represents an area where the leakage magnetic flux of the Hall IC becomes large and the accurate position of the rotor cannot be detected, and problems such as hunting of the rotation speed, reduction in efficiency, and increase in current are likely to occur. Furthermore, the state excluding the acceleration state or the deceleration state at the time of low speed and high speed is a steady state.

As described above, at high speeds, the leakage magnetic flux becomes large and the accuracy of detecting the position of the rotor deteriorates. Therefore, if only the position signal of the position sensor having a good position accuracy of the rotor is selected and used. In addition, even if the leakage magnetic flux becomes large, it is possible to suppress a decrease in the rotor position detection accuracy. Accordingly, stable rotation speed control can be performed, and hunting of the rotation speed, reduction in efficiency, increase in current, and the like are less likely to occur, and a highly reliable motor drive system can be obtained. Here, it is not necessary to select and use only the position signal of the position sensor with good rotor position accuracy only at high speeds, and only the position signal of the position sensor with good rotor position accuracy at low speed. May be selected and used.

Here, the method of switching the number of position signals to be used in accordance with the operation state (selecting a position signal with good position detection accuracy in accordance with the operation state among the n position signals) has been described. Since there are a plurality of combination patterns of the number of position signals of the attached position detection means 2 and the number of position signals to be selected, an example will be described below with respect to what kind of combination pattern there is in the case of three phases. FIG. 4 is a diagram showing an application example in a case where the number of signals of the position sensor to be used is switched according to the driving state. In the figure, the numeral is the number of position signals to be used. For example, in the case of pattern 1, switching is performed such that three position signals are used at startup and low speed, and one position signal is used at high speed. Is represented. Also, pattern 2 in the figure
In the case of (3), switching is performed such that three position signals are used at the time of startup and low speed, and the position signal is not used at the time of high speed (position sensorless control).

Also, in the case of pattern 3, 3
This means that switching is performed so that one position signal is used in a steady state (at a low speed and a high speed) by using one position signal. As can be seen from FIG. 4, the switching is performed so that a smaller number of position signals are used at the time of high speed than at the time of startup or at low speed. As described above, the numerical values in the figure are the number of position signals used by the position sensor, and a position signal number of 0 means position sensorless driving without using the position signal of the position sensor. In the case of the position sensorless drive, the position of the rotor is detected based on the current information of the current detection means 10 shown in FIG. When the position sensorless driving is not performed, the current detecting means 10 may not be provided. Similarly, in pattern 4, three position signals are used at the time of startup, and switching is performed so as to perform position sensorless driving in a steady state (low speed and high speed). In pattern 5, three position signals are used at startup. This means that two position signals are used at a low speed, and one position signal is used at a high speed.

Further, in the present embodiment, the number of position signals used at the time of starting is reduced as compared with the patterns 1 to 5 as shown in patterns 6 to 11 in FIG. Therefore, when there are a plurality of position sensors, there are cases where the position sensors cannot be mounted with high positional accuracy due to restrictions on the mounting positions.However, in the present embodiment, the number of position sensors is reduced, so that the degree of freedom of the mounting positions is reduced. Therefore, it is possible to provide a position detecting means with improved mounting position accuracy.

Therefore, the cost can be reduced by reducing the number of the position detecting means 2, and a highly reliable motor driving system with good rotor position detecting accuracy can be obtained.

Further, two or more position sensors may be mounted, and even at the time of start-up, two or one position signals having high position accuracy may be selected without using all the position signals. .

Further, in the case of the conventional position sensorless control that does not use a position sensor, it takes a long time to start up. However, in the present invention, the position sensor is used at the time of start up, and the position sensorless control is performed except for starting up. As described above, it does not take much time to start up, and a motor drive system with a quick start-up and high reliability can be obtained. Further, in the present embodiment, even when the position sensorless control is performed, at the time of start-up or low speed where the induced voltage is small and it is difficult to determine the step-out, for example, the pattern 2 in FIG.
4, 7, 9, 10, and 11, the position detecting means 2
It is also possible to use the position signal described above to determine the out-of-step and perform the position sensorless control at low speed or high speed when the induced voltage becomes large.

Further, since the position signal switching means 102 for selecting and using only the position signal having a high detection accuracy in accordance with the rotational speed among the n position signals is provided, the detection error can be reduced as compared with the prior art. The position can be reduced and an accurate position can be detected, and a highly reliable drive of the electric motor without occurrence of hunting of the rotation speed can be performed. Also, since the position signal of the position detecting means can be selected and used according to the speed, the rotational position can be accurately detected even in a low speed range,
Step-out determination can be made possible. In addition, it is possible to efficiently and stably drive the electric motor over a wide range.

Although the case where the position sensor is used as the position detecting means 2 has been described, the current detecting means 10 may be provided as the position detecting means 2 instead of the position sensor. In this case, for example, a current sensor is used as the current detecting means 10. In the case of three phases, the current for three phases or two phases is detected to detect the three phases.
What is necessary is just to select so that the current value of the phase with good current accuracy among the current values of the phases or two phases may be used.

Therefore, a current sensor such as a position sensor for detecting the rotor position of the synchronous motor or a current sensor for detecting a current flowing through the winding of the synchronous motor can be used as the position detecting means. Both the case and the case without the position sensor can be dealt with, and the degree of freedom in selecting the position detecting means is expanded. Further, when the current detecting means is used as the position detecting means, it is possible to cope with a compressor or the like in which it is difficult to mount a position sensor, and a motor drive system applicable to a wide range of products can be obtained. Also, the same effect can be obtained by using a combination of the position sensor and the current detecting means to select and switch both position signals.

Further, in the case of a three-phase synchronous motor, position signals of different phases, each having a fixed phase relationship with respect to the induced voltage generated by the winding of the three-phase synchronous motor, are output n (n
By providing (= 1, 2, 3) position detecting means, it is possible to reduce the size and cost, as compared with providing a plurality of position detecting means in one phase. Further, since the number of the position detecting means can be reduced, the degree of freedom of the mounting position of the position detecting means is increased.

Embodiment 2 In a second embodiment of the present invention, another example of a method of controlling the operating state (for example, the number of revolutions) of the electric motor in control means 3 described in the first embodiment using a three-phase synchronous motor as an example will be described. . Here, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

In the present embodiment, the position signal is
A method of controlling the number of revolutions of the electric motor using phase control will be described by taking as an example a case where a single position signal is used in a steady state. As described in the first embodiment, the synchronous motor is provided with three position detecting means 2 for outputting position signals (digital signals) of different phases having a fixed phase relationship with the induced voltage generated by the motor winding. As the position detecting means 2, a position sensor is mainly used, and among the position sensors, a Hall IC which has a simple structure and is inexpensive is used.

Hall I used as position detecting means 2
C outputs a position signal synchronized with the induced voltage signal corresponding to the rotational position of the rotor 7, but only the position signal with high accuracy is selected by the position signal switching unit 102. Based on the selected position signal, the voltage / phase determining means 104 applies the applied voltage /
The phase is determined, an energization waveform is formed with the determined applied voltage and phase, and a voltage is applied to the winding of the synchronous motor with the energization waveform to control the rotation speed of the motor.

Here, the position of the 3
A description will be given of a method of controlling the number of revolutions of a motor using phase control when only one Hall IC is used among the Hall ICs. The rising or falling edge of the position signal is detected for each carrier cycle, and the number of carriers between the edges is counted. For example, when the falling edge of the U phase is used, the number of carriers between the falling edges of the U phase is counted. The actual number of rotations is calculated using the counted number of carriers.

Here, the actual number of rotations can be obtained by (carrier frequency ÷ number of carriers ÷ number of rotor pole pairs). The actual rotation speed thus calculated is compared with the target rotation speed to determine a difference in the rotation speed, and the rotation speed can be controlled by calculating an effective voltage based on the difference in the rotation speeds and outputting it as a drive signal.

Normally, it is preferable to drive the motor by applying a voltage to the winding of the synchronous motor at an energization timing based on the induced voltage generated in the winding of the synchronous motor. Since the position signal output from the Hall IC is synchronized with the induced voltage signal, the present embodiment uses the position signal instead of directly detecting the induced voltage. Of course, if the induced voltage can be directly detected,
An induced voltage may be used.

Here, when the phase between the induced voltage and the motor current becomes equal, the motor driving efficiency becomes maximum. Therefore, it is better to control the phase of the applied voltage so that the phase between the induced voltage and the motor current becomes equal. . Here, if the phase angle θ between the applied voltage V and the induced voltage e (or the current I) when the phases of the induced voltage and the motor current are equal is referred to as an optimum phase angle, for example, What is necessary is just to set a range of the phase angle such that the motor efficiency and the current value are within an allowable range, and to control the phase of the applied voltage so as to obtain the target phase angle.

Hereinafter, as a method of controlling the phase of the applied voltage so as to obtain the target phase angle, an advanced phase reset control (also simply referred to as reset control) will be described. Here, the relationship between the phase voltage V per phase, the phase current I, the induced voltage e, the rotor (rotor) magnetic flux φ and the phase angle θ required for performing the reset control is shown in FIG.
This will be described with reference to FIG. FIG. 5 is a diagram for explaining the phase angle θ in the state of the optimum phase angle, and FIG.
FIG. 3 is a diagram illustrating a relationship between an applied voltage and a magnetic flux of a rotor (rotor). In FIG. 5, R is the motor winding resistance, I is the motor phase current, e is the induced voltage, V is the applied voltage, L is the inductance of the motor winding, and ω is the angular velocity (= 2 × pi π × frequency f). , Φ represent the magnetic flux vector of the rotor, and θ represents the phase of the applied voltage V with respect to the induced voltage e and the current I. In FIG. 6, the horizontal axis represents time, and the vertical axis represents induced voltage, rotor (rotor) magnetic flux, applied voltage, and output of the Hall IC.

In FIG. 5, the voltage component RI generated in the motor winding resistance R and the voltage component ωLI generated in the inductance L are 90 degrees out of phase, and the applied voltage V is the induced voltage e (position signal) or the phase current. The phase is shifted by θ from I. In the present embodiment, the phase difference θ = tan ⁻¹ (ωLI / (e + RI)) between the applied voltage V and the induced voltage e (or the phase current I) shown in FIG. The applied voltage V indicates that the phase is advanced by θ with respect to the induced voltage e (or the phase current I).

In FIG. 6, the amount of deviation between the applied voltage V and the induced voltage e corresponds to the phase angle θ, and the phase difference between the induced voltage e and the magnetic flux φ of the rotor (rotor) 7 is 90 degrees. Further, as can be seen from FIG. 6, the rising or falling of the output of the Hall IC corresponds to the MAX value or the MIN value of the output waveform φ of the magnetic flux of the rotor (rotor) 7.

Therefore, the applied voltage V of the winding of the stator 6
By controlling the phase difference between the induced voltage e and the induced voltage e (or the applied voltage V and the current I), the synchronous motor can be controlled at a rotational speed at which the efficiency is improved. That is, the rotor 7
And the induced voltage e (or the phase current I of the stator 6) are applied perpendicularly to each other, the torque generated by the stator 6 is given to the rotor 7 to the maximum, and the motor drive efficiency is increased. Can be maximized. In addition, the current and the loss can be reduced for the same rotation speed and the same load torque, and efficient operation can be performed.

Therefore, if the phase difference between the applied voltage V and the induced voltage e is controlled by providing the position detecting means 2, the applied voltage V
And the phase of the induced voltage e can be accurately grasped, so that the motor 30 can be controlled accurately and efficiently. Further, even if the phase difference between the applied voltage V and the current I is controlled by providing the current detecting means 10 and directly detecting the phase current I flowing into the motor 30, the phase of the applied voltage V and the current I can be controlled. Since it is possible to accurately grasp the electric motor 30, the electric motor 30 can be controlled accurately and efficiently.

Here, the configuration of the control means when performing the advanced phase reset control will be described with reference to FIG. FIG.
FIG. 3 is a diagram illustrating an example of a configuration of a control unit 3 when performing advanced phase reset control. In the figure, reference numeral 120 denotes a rotor position detecting means for detecting the position of the rotor 7 based on a position signal from the position detecting means 2, and 101 denotes a rotation based on information on the rotor position from the rotor position detecting means 120. The rotation number detecting means 121 for calculating the number is stored in advance in correspondence with the phase angle of the applied voltage with respect to the position signal (or the induced voltage having a certain phase relationship with the position signal) from the position detecting means 120 and the rotation number. A target phase angle (for example, a range of the phase angle such that the motor efficiency and the current value are within an allowable range with respect to the optimum phase angle) so that the phase angle of the applied voltage becomes the target phase angle. The phase changing means outputs phase information for changing the phase angle of the applied voltage to the voltage / phase determining means 124.

The phase changing means 121 uses the actual rotation speed obtained from the rotation speed detecting means 101 as the rotation speed commanding means 103.
By changing the phase angle of the applied voltage by a specified value in accordance with the difference between the actual rotation speed and the target rotation speed in comparison with the target rotation speed specified by (1), the rotation speed is also changed. Also,
If the phase angle corresponding to the rotation speed required for the actual rotation speed to reach the target rotation speed is set to the specified value, and the phase of the applied voltage is changed by the specified value, the actual rotation speed will become the target rotation speed. Can be changed to In order to improve the motor efficiency, both the applied voltage and the phase may be changed.

Reference numeral 102 denotes position signal switching means for switching the number of position signals to be used in accordance with the number of rotations. Reference numeral 124 denotes output of information on the phase angle of the applied voltage which is the target phase angle obtained by the phase changing means 121. And rotation speed detecting means 10
The voltage / phase determining means 105 for outputting an applied voltage and its phase necessary for the actual rotational speed to reach the target rotational speed using the information on the actual rotational speed obtained from 1 is a voltage / phase determining means 124. The inverter 5 which is the motor driving means actually converts the voltage value and phase determined by
This is an energization waveform forming means for generating an energization waveform so as to be output to the inverter 5 and outputting the generated waveform to the inverter 5 which is a motor driving means. Reference numeral 5 denotes a motor driving means,
A voltage is applied to the electric motor 30 by turning on and off a plurality of switching elements based on the conduction waveform formed by 5 to drive the electric motor 30.

Here, reference numeral 102 denotes the position detecting means 2 used in accordance with the number of revolutions as described with reference to FIG.
Is a position signal switching means for switching the number of position signals. Here, it is used when it is necessary to switch the number of position signals.

When the position signal from the rotor position detection means 120 is output to the rotation number detection means 101 in the control means 3, the rotation number detection means 101
The rotation frequency (number of rotations) is calculated based on the position signal from
2. Output to the voltage phase determining means 124. The phase changing unit 121 calculates the phase angle of the applied voltage with respect to the position signal (or the induced voltage having a fixed phase relationship with the position signal) from the position detecting unit 120 and the target phase angle stored in advance corresponding to the applied voltage. By comparison, the phase information for changing the phase angle of the applied voltage is output to the voltage / phase determining means 124 so that the phase angle of the applied voltage becomes the target phase angle. Further, the actual rotation speed obtained by the rotation speed detection means 101 is compared with the target rotation speed instructed by the rotation speed command means 103, and the phase angle of the applied voltage is set to a specified value so that the actual rotation speed becomes the target rotation speed. The phase of the applied voltage is changed by adding or subtracting only the applied voltage and output to the voltage / phase determining means 124.

The voltage / phase determining means 124 calculates the actual rotation speed obtained from the rotation speed detecting means 101 based on the phase information of the applied voltage from the phase changing means 121 and the position signal information from the position signal switching means 102. An applied voltage and its phase necessary to reach the target rotation speed are output to the conduction waveform forming means 105. The energization waveform forming means 105 generates an energization waveform such that the synchronous motor 30 is actually driven by the applied voltage and the phase determined by the voltage / phase determination means 124 and outputs the generated waveform to the motor drive means (inverter) 5. I do.

Therefore, in the present embodiment, there is provided a phase changing means for setting the target phase angle so that the optimum phase angle can be obtained by the above-described phase control.
The motor can be operated at a rotation speed at which the motor efficiency is improved, and an increase in current and an increase in loss can be prevented. In addition, since the actual rotation speed can be changed by changing the phase, if the voltage is applied to the motor at a phase that ensures the optimum phase angle state and matches the actual rotation speed to the target rotation speed, the rotation speed can be changed. Can be changed to the target rotational speed, and the state of the optimum phase angle is ensured, so that an increase in current and an increase in loss can be prevented. In addition, since the number of revolutions can be increased to the target value, a highly efficient and highly reliable motor drive system and a method for controlling the motor having a wide operating range can be obtained.

Further, as described in the first embodiment, n
If the position signal switching means 102 for selecting and using only a position signal with high detection accuracy in accordance with the number of rotations among the position signals is provided, the detection error is smaller than in the past, and the accurate position can be detected. As a result, it is possible to drive the electric motor with high reliability without causing hunting of the rotational speed. Further, since the position signal of the position detecting means can be selected and used in accordance with the speed, the rotational position can be accurately detected even in a low speed range, and the step-out determination can be made possible. In addition, it is possible to efficiently and stably drive the electric motor over a wide range.

Here, the rotor position detecting means 120 in FIG. 7 has been described so as to detect the rotor position based on the position signal from the position detecting means 2, but the current detecting means 10 shown in FIG. The current I may be detected, and the phase current I may be used in place of the position signal to detect the rotor position.

Further, the phase angle of the applied voltage with respect to the position signal (or the induced voltage having a fixed phase relationship with the position signal) is compared with a target phase angle stored in advance corresponding to the number of rotations to compare the applied voltage. Although the phase angle of the applied voltage is changed so that the phase angle becomes substantially the optimum phase angle, the current value detected by the current detection means 10 may be used as the position signal. This eliminates the need for the position detecting means, so that the motor can be driven at the target rotational speed even for an electric motor for a hermetic compressor in which the mounting of the position detecting means 2 is difficult. Can be prevented. In addition, since the rotation speed can be increased to the target value, efficient and highly reliable motor control can be performed.

Here, the control method of the phase angle θ will be described in detail by taking as an example a case where the optimum phase is obtained when the advance phase angle is 0 degree. FIG. 8 is a diagram illustrating the state of the advanced phase reset control, in which the horizontal axis represents time, and the vertical axis represents one-phase (for example, U-phase) output voltage waveform. In the figure,
This shows how the phase is corrected when the rotation cycle is changed from T0 to T1 during acceleration or the like. The waveform shown in FIG. 8 is, for example, a U-phase output voltage waveform. The mark ● in the figure indicates the timing of the optimum phase angle.

That is, FIG. 8 shows that the rotation period is changed from T0 to T1.
And the state of the phase reset control (reset control) when the rotation cycle is reduced. The upper waveform in FIG. 8 shows the case where no correction (reset) was performed, and the lower waveform corrects the lead angle cycle (reset control).
FIG.

As shown in the lower waveform of FIG. 8, if the phase angle is corrected, even if the period is changed from T0 to T1, T
The mark (optimum phase angle (0 degree)) should come for each 1 but if there is no correction (upper waveform in FIG. 8), the output waveform does not change even if the rotation cycle is changed from T0 to T1. Therefore, the timing (period T
It deviates from 1). Therefore, when the reset control is not performed, the optimum phase (marked by ●) does not come at the required timing, so that the current value increases and the efficiency deteriorates. Conversely, when the reset control is performed, even if the rotation cycle is changed, an optimum phase angle can be obtained in each rotation cycle, and efficient operation with a small current value can be performed.

In the case of performing advanced phase reset control (reset control), in FIG. 8, in the first section (A section) in which the cycle has changed, the waveform is output as the cycle T0 before the change. , Even when the waveform of the T0 cycle is being output, the waveform is reset when the first section has passed the time T1, and the waveform shifts to the second section (section B) to output a new waveform having the T1 cycle. That is, the phase angle is reset to the target phase at the timing when the optimum phase (indicated by ●) comes at the beginning of the second section, and the waveform of the T1 cycle is output. In the subsequent section (section C and thereafter), an optimal phase angle can be obtained by outputting a waveform of the cycle T1 and controlling the target phase angle at the timing of each T1 cycle.

As described above, by the advanced phase reset control (reset control), even if the rotation cycle changes, the waveform can be reset at the timing of each electric cycle, so that the phase can be controlled to be the optimum phase. Further, by resetting the phase of each rotation cycle to an optimal phase value corresponding to each rotation cycle by the advance phase reset control (advance phase reset control), the rotation speed can be increased to the target rotation speed.

Further, as shown in FIG. 9, even at the same rotation speed, the voltage and current can be shifted to smaller values, and the operation can be performed efficiently. FIG. 9 is a diagram for explaining how the current is reduced by the advanced phase reset control. In the figure, the horizontal axis represents the rotation speed, and the vertical axis represents the current value. By changing the phase from A to B according to the drawing, when the rotational speed is NB, the current value becomes I2 in the state of phase A.
However, by changing the phase to B, the current value can be reduced to I1 (I1 <I2) even at the same rotation speed NB. Therefore, since the current value can be reduced by performing the phase reset control, stable operation can be performed without stopping due to overcurrent, and a highly reliable and efficient motor drive system can be obtained.

Further, the case where the position sensor is used as the position detecting means 2 has been described, but the current detecting means 10 may be provided as the position detecting means 2 instead of the position sensor. In this case, for example, a current sensor is used as the current detecting means 10. In the case of three phases, the current for three phases or two phases is detected to detect the three phases.
What is necessary is just to select so that the current value of the phase with good current accuracy among the current values of the phases or two phases may be used.

Therefore, it is possible to use a current sensor such as a position sensor for detecting the rotor position of the synchronous motor or a current sensor for detecting a current flowing through the winding of the synchronous motor as the position detecting means. Both the case and the case without the position sensor can be dealt with, and the degree of freedom in selecting the position detecting means is expanded. Further, when the current detecting means is used as the position detecting means, it is possible to cope with a compressor or the like in which it is difficult to mount a position sensor, and a motor drive system applicable to a wide range of products can be obtained. Also, the same effect can be obtained by using a combination of the position sensor and the current detecting means to select and switch both position signals.

Further, in the case of a three-phase synchronous motor, n (n) outputs position signals of different phases each having a fixed phase relationship with respect to an induced voltage generated by a winding of the three-phase synchronous motor.
By providing (= 1, 2, 3) position detecting means, it is possible to reduce the size and cost, as compared with providing a plurality of position detecting means in one phase. Further, since the number of the position detecting means can be reduced, the degree of freedom of the mounting position of the position detecting means is increased.

Embodiment 3 In a third embodiment of the present invention, another configuration example of the control means 3 described in the first or second embodiment will be described using a three-phase synchronous motor as an example. In the present embodiment, the first embodiment
Control method in which the advanced phase reset control described in Embodiment 2 and the second embodiment are performed, and the voltage is increased to increase the rotational speed, but the rotational speed does not increase to a specified value. Despite performing (advance phase angle offset control) and this advance phase angle offset control, only voltage rises, rotation speed does not rise, and current rises due to voltage rise, and overcurrent flows, resulting in stable control. A control method (stall control (also referred to as rotational speed down control)) when there is a concern that the motor cannot be operated will be described.

First, the advance phase angle offset control (also referred to as offset control) will be described. Offset control means that a phase angle (advance phase angle) is further increased by Δθ from a reset value reset by advance phase reset control.
This is a control method that makes it possible to increase the number of revolutions by offsetting only (leading phase angle offset).

FIG. 10 is a diagram showing an example of the configuration of the control means 3 when performing the offset control according to the present invention. In the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. In the figure, reference numeral 120 denotes a rotor position detecting means for detecting the position of the rotor 7 based on a position signal from the position detecting means 2, and 101 denotes a rotation based on information on the rotor position from the rotor position detecting means 120. A rotation number detecting means 131 for calculating the number is a rotation number storing means for storing the actual rotation number obtained from the rotation number detecting means 101.

Reference numeral 134 denotes a voltage storage means for storing the applied voltage formed by the conduction waveform forming means 105; 132, a rate of change of the rotation speed obtained from the rotation number storage means 131 and a change rate of the voltage obtained by the voltage storage means 134 The target phase angle is changed by adding the specified angle Δθ (offset angle) to the target phase angle based on the target phase angle, and the phase angle is controlled so that the actual rotation speed becomes the target rotation speed from the rotation speed command means 103. Control means. 133 is a voltage determining means for determining the applied voltage and its phase angle based on the information on the phase angle from the phase angle control means 132.

105 generates an energization waveform so that the inverter 5 as the motor driving means can actually output the voltage value and the phase determined by the voltage determining means 133 to the synchronous motor 30, and sends the waveform to the inverter 5 as the motor driving means. This is an energization waveform forming means for outputting. Reference numeral 5 denotes a motor driving unit that drives the motor 30 by applying a voltage to the motor 30 by turning on and off a plurality of switching elements based on the conduction waveform formed by the conduction waveform forming unit 105.

The position signal from the rotor position detecting means 120 is output to the rotational speed detecting means 101 in the control means 3, and the rotational speed detecting means 101 detects the rotational frequency based on the position signal from the rotor position detecting means 120. (Rotation speed) is calculated and output to the rotation speed storage means 131. The number-of-revolutions storage means 131 stores information on the number of rotations for a required period and calculates the rate of change. Similarly, the voltage storage means 134 stores the information of the applied voltage for a necessary period and calculates the change ratio. The phase angle control means 132 determines whether to perform advance phase angle offset control (also referred to as offset control) according to the change rate of the rotation speed obtained from the rotation speed storage means 131 and the change rate of the voltage obtained from the voltage storage means 134. If it is determined that the target phase angle is required, an offset control is performed by setting an offset flag and adding Δθ (offset angle) to the target phase angle. That is, the rotation speed command means 10
The phase angle is offset so that the target rotation speed specified by 3 is obtained.

The voltage determining means 133 uses the applied voltage and the necessary rotating speed obtained by the rotating speed detecting means 101 based on the applied voltage and the phase information from the phase angle controlling means 132 so that the actual rotating speed becomes the target rotating speed. The phase is output to the conduction waveform forming means 105. The energization waveform forming means 105 generates an energization waveform such that the synchronous motor 30 is actually driven by the applied voltage determined by the voltage determination means 133 and the phase thereof, and outputs the generated waveform to the motor driving means (inverter) 5.

Therefore, in the present embodiment, the phase angle control means is provided to offset the phase angle (leading phase angle) by a predetermined amount. Therefore, it is instructed to increase the voltage to increase the rotation speed. In spite of the above, the rotation speed is not increased only by the increase of the voltage, so that a wide range of operation can be performed, and moreover, stable control can be performed.

Here, despite the above-described offset control, only the voltage increases and the number of revolutions does not increase.
If there is a concern that the current will increase due to the voltage rise and an overcurrent will flow to make it impossible to perform stable control, stall control (rotation speed reduction control) may be performed. FIG. 11 is a diagram illustrating an example of a configuration of the control unit 3 when performing stall control.
In the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. In the figure, reference numeral 120 denotes a rotor position detecting means for detecting the position of the rotor 7 based on the position signal from the position detecting means 2, and 101 denotes a rotor position detecting means 12
Rotational speed detecting means 131 for calculating the rotational speed based on the information of the rotor position from 0, and 131 is a rotational speed storing means for storing the actual rotational speed obtained from the rotational speed detecting means 101.

Reference numeral 134 denotes a voltage storage means for storing the applied voltage formed by the conduction waveform forming means 105; 137, a change rate of the rotation speed obtained from the rotation speed storage means 131 and a change rate of the voltage obtained by the voltage storage means 134 Is a predetermined number of revolutions (Nd) subtracted from the target number of revolutions obtained by the number of revolutions commanding means 103 based on the target number of revolutions to reduce the target number of revolutions and output as a new target number of revolutions.
138 is a voltage determining means for determining the applied voltage and its phase angle based on the information on the target rotational speed from the rotational speed determining means 137.

105 generates an energizing waveform so that the inverter 5 serving as the motor driving means can actually output the voltage value and the phase determined by the voltage determining means 138 to the synchronous motor 30, and sends the waveform to the inverter 5 serving as the motor driving means. This is an energization waveform forming means for outputting. Reference numeral 5 denotes a motor driving unit that drives the motor 30 by applying a voltage to the motor 30 by turning on and off a plurality of switching elements based on the conduction waveform formed by the conduction waveform forming unit 105.

The position signal from the rotor position detection means 120 is output to the rotation number detection means 101 in the control means 3, and the rotation number detection means 101 determines the rotation frequency based on the position signal from the rotor position detection means 120. (Rotation speed) is calculated and output to the rotation speed storage means 131. The number-of-revolutions storage means 131 stores information on the number of rotations for a required period and calculates the rate of change. Similarly, the voltage storage means 134 stores the information of the applied voltage for a necessary period and calculates the change ratio. The rotation speed determining unit 137 determines whether to perform stall control (rotation speed down control) according to the change ratio of the rotation speed obtained from the rotation speed storage unit 131 and the change ratio of the voltage obtained from the voltage storage unit 134, and determines If it is determined that the engine speed has been stopped, a flag for stall control is set, and a control is performed to reduce the target rotation speed by reducing the predetermined rotation speed Nd from the target rotation speed Nx to lower the actual rotation speed. That is, the rotation speed command means 10
3, the target rotation speed specified by the instruction is reduced, the voltage command value is reduced, and the actual rotation speed is also reduced.

The voltage determining means 138 determines the applied voltage and the necessary voltage so that the actual rotation speed obtained from the rotation speed detecting means 101 on the basis of the applied voltage and the phase information from the rotation speed determining means 137 becomes the target rotation speed. The phase is output to the conduction waveform forming means 105. The energization waveform forming means 105 generates an energization waveform such that the synchronous motor 30 is actually driven by the applied voltage determined by the voltage determination means 138 and its phase, and outputs the generated waveform to the motor drive means (inverter) 5.

Therefore, in the present embodiment, the rotation speed determining means is provided to reduce the target rotation speed by a predetermined amount. Therefore, even when the voltage only increases and the rotation speed does not increase, the overcurrent As a result, the motor 30 can be stopped and demagnetization due to overcurrent does not occur, so that a wide-range operation can be performed, and a highly reliable motor drive system and a control method of the motor that can perform stable control can be obtained.

Here, the advance phase angle offset control and the stall control will be described in detail with reference to FIG. FIG. 12 is a flowchart for explaining a determination method leading to advance phase angle offset control and stall control.
Here, a description will be given of a flow until the offset control is executed when the detected rotational speed N is smaller than the rotational speed command value and the rotational speed is to be increased. In the figure, at the time of attachment, the value of the counter for control is used, the state of n at the time of attachment indicates the current state, and the value of 0 at the time of attachment indicates that the counter has been cleared.

It is assumed that the determination in FIG. 12 is repeated for each predetermined condition. First, it is determined in ST1 whether or not the vehicle is in operation. If the vehicle is not in operation, the process proceeds to ST2, where 0 is stored in the offset control flag (F ← 0) and the offset control is not performed. In ST3, 0 is also stored in the stall control flag (G ← 0), and the stall control is not performed. Stores the current voltage Vn to the voltage _{V 0} at the time of the counter is cleared by then ST4 and (Vn ← _{V 0),} stores 0 in the rotation number N0 at the time of the counter is cleared at ST5 _{(N 0} ← _0), in ST6 And stores 0 in the offset frequency F _offset (F _offset ←
0).

If it is determined in ST1 that the vehicle is running, it is determined in ST11 whether or not the vehicle is under stall control. If it is during stall control, it is determined in ST12 whether the set time has been exceeded.
At T13, 0 is stored in the stall control flag G (G ← 0), and the stall control ends. If it is determined in ST11 that stall control is not being performed, the current voltage (Vn) is compared with the previous voltage (Vn-1) in ST21, and the voltage rises from the previous voltage. If there is, in ST22, it is determined whether or not the difference between the current voltage (Vn) and the voltage (V ₀ ) at the time of clearing the counter is larger than a predetermined value (ΔV).

That is, it is determined whether (Vn)-(V0)> ΔV. In ST22, the difference between the current voltage (Vn) and the voltage (V0) at the time of clearing the counter is a specified value (ΔV).
If it is larger, the process proceeds to ST23, where it is determined whether the difference between the current rotational speed (Nn) and the rotational speed (N0) when the counter is cleared is equal to or less than a predetermined value (ΔN). I do. That is, (Nn) − (N0) <Δ
N or not, and from ST22 and ST23,
((Nn−N0) / (Vn−V0)) is a predetermined value K (ΔN
/ ΔV). Here, the counter is cleared to 0 when the voltage does not change or decreases. If ST2
If the determination is NG in 1 or ST23, S
Stores the value of _{V n} to willing _{V 0} to T41 _{(V 0} ← _V n)
, And stores the value of _{N n} to _{N 0} at ST42 _{(N 0} ← _N n)
To clear the counter.

If (Nn)-(N0) <ST23
If it is determined that ΔN, Vn is added to V0 in ST24.
, And the value of Nn is stored in N0 in ST25. In ST26, it is determined whether or not offset control is being performed (determination of whether F = 1). If offset control is not being performed (if F = 0), an offset control flag is set in ST27 (F ← 1) Execute offset control for adding a specified angle Δθ (offset angle) to the target phase angle. Then, the electric frequency (Fn) at this time is stored as an offset frequency (Foffset) (F
offset ← Fn).

If the offset control is being performed in ST26, the offset frequency (Foffset) is determined in ST31.
And the current frequency (Fn). If the offset frequency (Foffset) is the current frequency (Fn)
If it is larger than the offset frequency (Fo) at ST32.
ffset) stores the current frequency (Fn) (Foff
set ← Fn). If the current frequency (Fn) is equal to or higher than the offset frequency (Foffset) in ST31, a stall control flag is set in ST33 (G ←
1) Stall control is performed.

Here, the offset control and the stall control will be described in detail with reference to FIG. FIG. 13 is a diagram showing how the voltage and the rotation speed change during offset control and stall control. In the figure, the horizontal axis represents time, and the vertical axis represents a voltage command value, actual rotation speed, phase angle, and rotation speed. In the figure, the section is a section during acceleration, and when a voltage command value is set so as to reach the target rotation number, the actual rotation number also increases, and the actual rotation number increases to A1. The actual rotation speed at this time is expressed as N5 = A1 using the value of the counter. Here, the subscript 5 of N5 represents the number of counters.

In the present embodiment, the rising value of the voltage is the specified value Δ
V (ST22), the determination in the flowchart described with reference to FIG. 12, that is, ((Nn-N0) / (Vn-V
0)) is smaller than a predetermined value K (= ΔN / ΔV) (ST22, ST23) (ST23). The interval is divided every time when ΔV is reached or each time the counter is cleared. A description will be given with circle numbers.
In the section, since (N5−N0) / (V5−V0)> K, the determination is OK. If the determination is OK, the values of N7 and V7 are respectively stored in N0 and V0 without performing offset control (ST41, ST42), and then the value of the counter is set to 0, and the voltage command value is further increased (counter n =
0 → 1 → 2 →... → 7), an attempt is made to make the actual rotational speed coincide with the target rotational speed.

In the section, although the voltage is increased by the voltage command (ST21), the actual rotation speed does not increase more than A3. If the above determination is made in this state (end of section), (N7−N0) / (V
7−V0) <K, and the determination is NG (ST22,
ST23). Then, the values of N7 and V7 are respectively stored in N0 and V0 (ST24, ST25), and then the value of the counter is reset. Thereafter, the offset control flag is set (F = 1) (ST27), and the offset frequency (Foffset) is reset. The current frequency (Fn) is stored (ST28), and offset control is executed.

When the offset control flag is set in the section (F ← 1), the offset control for adding the offset (Δθ) to the target phase angle α is executed at the beginning of the section (S).
T27). Then, the actual rotation speed increases from A3 to A4, and an increase in the rotation speed is obtained. Here, the flag of the offset control is maintained until a stop command is issued. Then, offset control determination is performed again in another section. If it is determined that offset control is necessary, ST
At 26, it is determined whether or not the offset control is being performed (whether or not the offset control flag is set).

If the flag is set, ST3
At step 1, the offset frequency (Foffset) is compared with the current frequency (Fn). If the current frequency is lower than the offset frequency, the offset frequency is reduced in ST32. That is, the current frequency (Fn)
Is stored in the offset frequency (Foffset).

Despite the offset control, the rotation speed cannot be increased and only the voltage continues to increase, and the offset control is determined again. In ST31, it is determined that the current frequency is higher than the offset frequency. In this case, a flag for stall control (rotation speed reduction control) is set (G = 1) to perform stall control in ST33, and stall control is executed.

The stall control (rotation speed reduction control) is a control for lowering the target rotation speed for a certain period of time (during the section time Td in FIG. 13) in order to prevent overcurrent interruption due to an increase in current and demagnetization of the motor magnet. (In FIG. 13, the control is performed to decrease by Nd).

In the section of FIG. 13, although the voltage is increased by the voltage command (ST21), the actual number of revolutions has not reached the specified value. That is, in the section, the increase in the number of revolutions is equal to or less than ΔN ((Nn−N0) / (Vn−V0) <K) with respect to the specified value of voltage rise (ΔV). When this state determination is performed, (N5-N
0) / (V5−V0) <K, and the determination is NG (ST22, ST23).

Then, after the values of N5 and V5 are stored in N0 and V0, respectively (ST24, ST25), the value of the counter is reset, and it is determined whether or not the offset control is being performed (ST26). Therefore, in ST31, it is determined whether or not the offset frequency is higher than the current frequency. For sections,
Since the current frequency is higher than the offset frequency (in FIG. 13, the offset frequency indicates the rotation speed A3 at the time of executing the offset control in the section), ST3
Proceeding to 3, the stall control flag is set (G = 1), and the stall control is executed.

That is, the target rotation speed is reduced from Nx by Nd only to the section time (Td time only) and changed to Ny. Then, in the section, the voltage command value decreases and the actual rotation speed also decreases. Then, after the elapse of the Td time (section)
Returns the rotation speed command value to the target rotation speed Nx, returns to the state where only the phase lead angle reset control (phase control) can be executed, and waits for the offset control execution determination. As described above, by lowering the target rotation speed, the execution voltage Vn and the rotation speed Nn can be reduced, and the current increase accompanying the voltage increase, that is, overcurrent interruption and demagnetization can be prevented. Thus, a highly reliable motor drive system can be obtained.

Further, Embodiment 1 or Embodiment 2
If the phase changing means described in (1) is provided, it is possible to apply an applied voltage and a phase to the electric motor such that the actual rotational speed matches the target rotational speed. And an increase in loss can be prevented. In addition, since the rotation speed can be increased to the target value, efficient and highly reliable motor control can be performed.

Further, although not shown in FIGS. 10 and 11, as described in the first embodiment (FIG. 2) and the second embodiment (FIG. 7), the n If the position signal switching means for selecting and switching only the position signal having high detection accuracy in accordance with the rotation speed among the position signals is provided, the detection error can be reduced and the accurate position can be detected as compared with the related art.
It is possible to drive the motor with high reliability without causing hunting of the rotation speed. In addition, since the position signal of the position detecting means can be selected and used according to the speed, the rotational position can be accurately detected even in a low-speed range, and the step-out judgment can be performed. The electric motor can be driven.

Further, as described in the first embodiment, in the case of a three-phase synchronous motor, position signals of different phases each having a fixed phase relationship with respect to an induced voltage generated by a winding of the three-phase synchronous motor. Is provided, n (n = 1, 2, 3) position detecting means can be provided, so that downsizing and cost reduction can be achieved as compared with providing a plurality of position detecting means in one phase. Further, since the number of the position detecting means can be reduced, the degree of freedom of the mounting position of the position detecting means is increased.

[0131]

The motor driving system according to the first aspect of the present invention outputs a position signal having a fixed phase relationship with the induced voltage generated by the winding of the synchronous motor (n: n:
The number of position signals to be used is determined by selecting position signals to be used in accordance with the operating state from among the (n or more integers) position detecting means and the n position signals output by the n position detecting means. A position signal switching unit to be changed, a conduction waveform forming unit for forming a conduction waveform of the synchronous motor based on the position signal selected by the position signal switching unit, and synchronization based on the conduction waveform formed by the conduction waveform forming unit. Motor driving means for driving a synchronous motor by applying a voltage to the windings of the motor, so that even in an operation state where the amount of leakage magnetic flux of the Hall IC is large, it is possible to select a Hall IC that can be accurately detected, Therefore, the detection error is smaller than in the prior art, the accurate position can be detected, and the motor can be driven with high reliability without occurrence of hunting of the rotational speed.

In the motor drive system according to the second aspect of the present invention, the number of position signals to be used is switched according to the rotation speed of the synchronous motor, so that a stable and efficient motor drive system can be obtained over a wide range. Can be. Then, by selecting and using the signal of the position sensor in accordance with the speed, the rotational position can be accurately detected even in a low speed range, and the step-out determination can be made possible.

The motor drive system according to the third aspect of the present invention uses n position signals at least at the time of startup or low-speed rotation, and uses less than n position signals at other rotation speeds. Therefore, it is possible to efficiently and stably drive the electric motor over a wide range.

A motor drive system according to a fourth aspect of the present invention comprises: a rotation speed detecting means for detecting a rotation speed of a synchronous motor based on a position signal from a position detecting means; and a synchronous motor for the position signal. Phase changing means for changing the phase difference of the applied voltage with respect to the position signal by grasping the phase difference of the applied voltage and adjusting the phase difference by a predetermined value; and based on the applied voltage changed by the phase changing means and its phase. An energization waveform forming means for forming an energization waveform for driving the synchronous motor; and changing a phase of a voltage applied when the number of rotations detected by the number of rotations detection means is out of a target number of rotations. As a result, the increase in current and loss can be prevented, and the number of rotations can be increased to the target value to drive the motor with high efficiency and high reliability. It can be carried out.

In the motor drive system according to the fifth aspect of the present invention, a position sensor for detecting a rotor position of the synchronous motor or a current detecting means for detecting a current flowing through a winding of the synchronous motor is used as the position detecting means. Since this is done, it is possible to cope with both the case where there is a position sensor and the case where there is no position sensor, and the degree of freedom in selecting the position detecting means is expanded. Further, when the current detecting means is used as the position detecting means, it is possible to cope with a compressor or the like in which it is difficult to mount a position sensor, and a motor drive system applicable to a wide range of products can be obtained.

The motor drive system according to the sixth aspect of the present invention outputs n (n) position signals of different phases each having a fixed phase relationship with respect to an induced voltage generated by a winding of a three-phase synchronous motor. Since (= 1, 2, 3) position detecting means are provided, the size and cost can be reduced as compared with the case where a plurality of position detecting means are provided in one phase. Further, since the number of the position detecting means can be reduced, the degree of freedom of the mounting position of the position detecting means is increased.

A motor drive system according to a seventh aspect of the present invention comprises: a rotation speed detecting means for detecting a rotation speed of a synchronous motor; a voltage storage means for storing a change ratio of a voltage value applied to the synchronous motor; A number-of-revolutions storage means for storing a change rate of the number of revolutions detected by the number-of-revolutions detection means, and a change rate of a change amount of the number of revolutions obtained by the number-of-revolutions storage means with respect to a change amount of the voltage obtained by the voltage storage means. Phase angle control means for calculating and changing the phase angle of the applied voltage applied to the synchronous motor by a predetermined amount according to the rate of change, so that the number of rotations can be increased to a specified value and a wide range of operation can be performed. It is possible to obtain an electric motor capable of performing the following.

The motor drive system according to the eighth aspect of the present invention comprises: a rotation speed detecting means for detecting a rotation speed of the synchronous motor; a voltage storage means for storing a rate of change of a voltage value applied to the synchronous motor; A number-of-revolutions storage means for storing a change rate of the number of revolutions detected by the number-of-revolutions detection means, and a change rate of a change amount of the number of revolutions obtained by the number-of-revolutions storage means with respect to a change amount of the voltage obtained by the voltage storage means. And rotation speed determining means for changing the target rotation speed.
An overcurrent interruption due to an increase in current can be prevented, and a highly reliable electric motor capable of preventing the current from rising to near the demagnetization level and demagnetizing the magnetic flux of the rotor can be obtained.

The motor control method according to the ninth aspect of the present invention detects a position signal having a fixed phase relationship with respect to an induced voltage generated in a synchronous motor or an induced voltage generated in a winding of the synchronous motor. Then, a phase angle of the applied voltage with respect to the induced voltage or the position signal is compared with a target phase angle stored in advance corresponding to the rotation speed, and a voltage applied so that the phase angle of the applied voltage becomes the target phase angle. A phase changing step of changing the phase angle of the phase and outputting phase information; an energizing waveform forming step of forming an energizing waveform for driving the synchronous motor based on the phase information obtained from the phase changing step; A motor driving step of driving the synchronous motor by applying a voltage to the winding of the synchronous motor based on the conduction waveform formed by the step. It is possible to operate the motor at a rotational speed is improved, it is possible to prevent an increase in loss and an increase in current.

A motor control method according to a tenth aspect of the present invention includes a rotation speed detection step for detecting a rotation speed of a synchronous motor, and the actual rotation speed detected in the rotation speed detection step is set to a target rotation speed. Since the voltage value or the phase angle of the applied voltage is changed in such a manner, the operation can be performed at the target rotation speed, and a wide operation range can be obtained.

According to an eleventh aspect of the present invention, there is provided a method for controlling a motor, comprising: a rotation number storing step of storing a change rate of a rotation number of the synchronous motor; and a voltage storing a change rate of an applied voltage applied to the synchronous motor. The storage step and the change rate of the rotation speed obtained from the rotation number storage step and the change rate of the applied voltage obtained from the voltage storage step are respectively compared with predetermined values to change the phase angle of the applied voltage or to change the target rotation. A step of changing the number of rotations and an energization waveform for changing the rotation speed of the synchronous motor based on the information on the phase angle of the applied voltage or the information on the target rotation speed changed in the comparison change step. A voltage is applied to the winding of the synchronous motor based on the current waveform formed in the current waveform forming step and the current waveform formed in the current waveform forming step. A motor driving step of moving, because with a, can extensive operation, yet control method for a reliable motor capable of stable control is obtained.

In the motor control method according to the twelfth aspect of the present invention, n (n: n) having a fixed phase relationship with an induced voltage generated in a synchronous motor or an induced voltage generated in a winding of the synchronous motor. A position signal detecting step of detecting (integral number of 1 or more) position signals, and a position to be used by selecting a position signal to be used in accordance with the operation state from the n position signals detected by the position signal detecting step. A position signal switching step of changing the number of signals, the detection error is smaller than in the past, an accurate position can be detected, and a highly reliable motor drive that does not cause hunting of the rotational speed or the like is performed. Can be. Further, since the position signal of the position detecting means can be selected and used in accordance with the speed, it is possible to efficiently and stably drive the electric motor over a wide range.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a synchronous motor drive system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a configuration of a control unit according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a position signal waveform for three phases according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an application example in the case where the number of signals of a position sensor to be used is switched according to the driving state according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a phase angle θ according to the second embodiment of the present invention.

FIG. 6 is a diagram illustrating a relationship among an induced voltage, an applied voltage, and a magnetic flux of a rotor (rotor) according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating an example of a configuration of a control unit when performing advanced phase reset control according to the second embodiment of the present invention.

FIG. 8 is a diagram illustrating a state of advanced phase reset control according to the second embodiment of the present invention.

FIG. 9 is a diagram for explaining a state where a current is reduced by advanced phase reset control according to the second embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of a configuration of a control unit 3 when performing offset control according to the third embodiment of the present invention.

FIG. 11 is a diagram illustrating an example of a configuration of a control unit 3 when performing stall control according to a third embodiment of the present invention.

FIG. 12 is a flowchart illustrating a method of determining leading phase angle offset control and stall control according to a third embodiment of the present invention.

FIG. 13 is a diagram illustrating a state of a change in voltage and rotation speed during offset control and stall control according to the third embodiment of the present invention.

FIG. 14 is a schematic diagram showing a configuration of a conventional synchronous motor drive circuit.

FIG. 15 is a diagram illustrating a relationship between a rotation speed and a leakage magnetic flux when a Hall IC is used.

FIG. 16 is a diagram illustrating a relationship between a motor rotation speed and a current.

[Explanation of symbols]

1 power supply, 2 position detection means, 3 control means, 4 converter, 5 motor drive means (inverter), 6 stator, 7 rotor, 10 current detection means, 20 position sensor, 30 motor, 31 control means. 101 rotation speed detection means, 102 position signal switching means, 103 rotation speed command means, 104 voltage phase determination means, 105 conduction waveform formation means, 120 rotor position detection means, 121 phase change means, 124 voltage / phase determination means, 125 Energization waveform forming means, 131 rotation number storage means, 132 phase control means, 133 voltage determination means, 134 voltage storage means, 137 rotation number determination means, 138 voltage determination means.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Taido Sakamoto, Inventor 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Katsuhiko Saito 2-2-2-3 Marunouchi, Chiyoda-ku, Tokyo F term in Mitsubishi Electric Corporation (reference) 5H560 AA01 BB04 BB12 DA03 DA12 DA17 DA18 DA19 DA20 DB14 DB20 DC12 EB01 HA02 HA03 XA04 XA11 XA15

Claims (12)

[Claims] An output device outputs a position signal having a constant phase relationship with respect to an induced voltage generated by a winding of a synchronous motor.
(N: an integer greater than or equal to 1) position detecting means, and a position to be used by selecting a position signal to be used in accordance with an operation state from among the n position signals output by the n position detecting means. Position signal switching means for changing the number of signals; conduction waveform forming means for forming a conduction waveform of the synchronous motor based on the position signal selected by the position signal switching means; A motor driving means for driving the synchronous motor by applying a voltage to the winding of the synchronous motor based on the supplied current waveform. 2. The motor drive system according to claim 1, wherein the number of position signals to be used is switched according to the rotation speed of the synchronous motor. 3. The apparatus according to claim 1, wherein n position signals are used at least at the time of start-up or low-speed rotation, and the number of position signals to be used is reduced to less than n at other rotation speeds. 3. The motor drive system according to 2. 4. A rotational speed detecting means for detecting a rotational speed of a synchronous motor based on a position signal from a position detecting means, and a phase difference between an applied voltage applied to the synchronous motor with respect to the position signal is grasped. Phase changing means for changing the phase difference of the applied voltage with respect to the position signal by adding or subtracting a predetermined value, and driving the synchronous motor based on the applied voltage and the phase changed by the phase changing means. Power supply waveform forming means for forming a power supply waveform, the target rotation speed and the target rotation speed by changing the phase of the voltage applied when the rotation speed detected by the rotation speed detection means is out of the target rotation speed The synchronous motor drive system according to any one of claims 1 to 3, wherein: 5. A position sensor for detecting a rotor position of a synchronous motor or a current detector for detecting a current flowing through a winding of said synchronous motor as said position detecting means. Item 5. The synchronous motor drive system according to any one of Items 1 to 4. 6. N (n = 1, 2, 3) position detecting means for outputting position signals of different phases each having a fixed phase relationship with respect to an induced voltage generated by a winding of a three-phase synchronous motor. The synchronous motor drive system according to any one of claims 1 to 5, further comprising: 7. A rotating speed detecting means for detecting a rotating speed of the synchronous motor, a voltage storing means for storing a rate of change of a voltage value applied to the synchronous motor, and a rotating speed detected by the rotating speed detecting means. Rotation rate storage means for storing the change rate of the rotation speed, and the change rate of the change rate of the rotation speed obtained by the rotation speed storage means with respect to the change amount of the voltage obtained by the voltage storage means, and according to the change rate 7. The motor drive system according to claim 1, further comprising: a phase angle control unit that changes a phase angle of an applied voltage applied to the synchronous motor by a predetermined amount. 8. A rotating speed detecting means for detecting a rotating speed of the synchronous motor, a voltage storing means for storing a rate of change of a voltage value applied to the synchronous motor, and a rotating speed detected by the rotating speed detecting means. Rotation speed storage means for storing a change rate of the rotation speed, and a rotation for changing a target rotation speed in accordance with a change rate of a change rate of the rotation speed obtained by the rotation speed storage means with respect to a change amount of the voltage obtained by the voltage storage means. The motor drive system according to any one of claims 1 to 7, further comprising: a number determination unit. 9. An induced voltage generated in a synchronous motor or a position signal having a fixed phase relationship with an induced voltage generated by a winding of the synchronous motor is detected, and a voltage applied to the induced voltage or the position signal is detected. By comparing the phase angle of the applied voltage with the target phase angle stored in advance corresponding to the number of rotations, the phase information of the applied voltage is changed so that the phase angle of the applied voltage becomes the target phase angle. A phase changing step to output, an energizing waveform forming step of forming an energizing waveform for driving the synchronous motor based on the phase information obtained from the phase changing step, and an energizing waveform formed by the energizing waveform forming step A motor driving step of driving the synchronous motor by applying a voltage to the winding of the synchronous motor based on Your way. 10. A rotating speed detecting step for detecting a rotating speed of a synchronous motor, wherein a voltage value or a phase angle of an applied voltage is adjusted so that an actual rotating speed detected in the rotating speed detecting step becomes a target rotating speed. The method for controlling an electric motor according to claim 9, wherein the method is changed. 11. A rotation number storage step for storing a change rate of a rotation number of the synchronous motor, a voltage storage step for storing a change rate of an applied voltage applied to the synchronous motor,
The change rate of the rotation speed obtained from the rotation speed storage step and the change rate of the applied voltage obtained from the voltage storage step are respectively compared with predetermined predetermined values to change the phase angle of the applied voltage or to change the target rotation speed. A comparison change step of performing a change, and energization for changing and driving the rotation speed of the synchronous motor based on the information on the phase angle of the applied voltage or the information on the target rotation speed changed in the comparison change step. An energization waveform forming step of forming a waveform, and a motor driving step of applying a voltage to the winding of the synchronous motor based on the energization waveform formed in the energization waveform forming step to drive the synchronous motor. A method for controlling an electric motor, comprising: 12. Detecting n (n: an integer of 1 or more) position signals having a fixed phase relationship with an induced voltage generated in a synchronous motor or an induced voltage generated by a winding of the synchronous motor. A position signal detecting step, and a position signal switching step of changing a number of position signals to be used by selecting a position signal to be used according to an operation state among the n position signals detected by the position signal detecting step. The method of controlling an electric motor according to at least one of claims 9 to 11, further comprising: