JP2609840B2 - Motor control method - Google Patents

Description

The present invention relates to a control method for an electric motor having a rotor that rotates with magnetism.

(B) Prior art Electric motors having a rotor that rotates with magnetism include, for example, an electric motor having a coil for forming magnetic poles in the rotor or an electric motor having a magnet embedded in the rotor. Is widely used as a commutatorless DC motor, an AC servomotor, an AC synchronous motor, etc., in which a ferrite magnet is attached to a rotor.

FIG. 1 shows a typical example of a drive circuit for such a commutatorless DC motor. In the figure, 1 is a single-phase AC power supply,
Reference numeral 2 denotes a rectifier circuit, which has a well-known thyristor bridge circuit and the like, although the specific configuration of the rectifier circuit is not shown. Reference numeral 3 denotes an inverter for generating a rotating magnetic field in the stator 4 using the DC rectified by the rectifier circuit 2. The elements constituting the inverter 3 may be thyristors or other switching elements as long as they can perform switching control in response to a signal from a control circuit 5 described later, but in the following description, six thyristors connected as shown in FIG. shows the transistor Tr ₁ to Tr ₆ as a representative example will be described. Reference numeral 5 denotes a control circuit which outputs a signal for performing ignition control of the transistors constituting the inverter 3 in a predetermined order, and detects a rotor position mainly using the Hall elements H ₁ , H ₂ and H _3. It has a configuration that determines the firing order point of the transistor Tr ₁ to Tr ₆ of the inverter 3 a rotational position of the rotor 7 which is detected as an input signal in a vessel. In addition, it described in the rotor 7.
N and S indicate magnetic poles magnetized on the surface of the rotor 7.

An operation outline of the commutatorless DC motor having such a configuration will be described. The control circuit 5 supplied with the DC voltage from the single-phase AC power supply 1 via the rectifier circuit 2 receives the signal of the rotational position of the rotor 7 obtained from the position detector 6 as an input, and the transistors Tr _{1 to} Tr of the inverter 3 ₆ , for example, a signal as shown in FIG. 2 is given. That is, when a control voltage is applied to each transistor in the first firing mode so that the transistors Tr ₁ and Tr ₅ are turned on and the other transistors Tr _{2 to} Tr ₄ and Tr ₆ are turned off, the voltage between the stator windings UV is increased. , A current flows as shown by the arrow I in the figure, and then (second ignition mode) the transistor Tr
_1, Tr ₆ to ON, by controlling the respective transistors so as to turn OFF the other transistor Tr ₂ to Tr _5, in FIG between the windings UW arrow
Current like II, plus transistor in 3rd firing mode
When Tr ₂ and Tr ₆ are turned on and the others are turned off, a current flows between the windings VW of the stator as shown by the arrow III in the figure. Similarly to the third sequential transistor Tr ₁ to Tr ₆ from ignition mode until the sixth ignition mode with is igniting controlled as shown in FIG. 2 b, the cycle of such first to sixth ignition mode Repeated.

Due to the output of the ignition control from the control circuit 5, a current flows through the stator 4 in the above-described direction, and the relationship with each mode is schematically shown in FIG. A chart is obtained. In each of U, V, and W phases in the figure, the continuity display above the center line indicates that a current flows from the entrance of each phase toward the neutral point N in the stator 4 in FIG. The continuity display on the side indicates that a current is flowing from the neutral point N toward the windings U, V, W of each phase.

In this way, when a current flows through the stator windings U, V, W, a rotating magnetic field is formed in the stator 4, so that, for example, one point of the rotor 7 is set in each ignition mode from the point in FIG. In response, the motor 7 makes one rotation, and thereafter, the rotor 7 turns and can continue to operate as an electric motor in accordance with the sequentially repeated mode.

However, the electric motor of the conventional此species, the Hall elements H _1, H _2, H ₃ embedded in three positions of the portions of the stator 4 as a sensor for detecting the rotational position of the rotor 7, the Hall element H ₁ or uses a control unit 5 that detects each rotational state of the rotor 7 by H _3, fixed windings U based on the detected position, V, control of energization of the W to. For this reason, it is difficult to operate the motor corresponding to various load conditions in which the motor is used, or not only is it necessary to precisely process and assemble the used parts and structure of the motor, but also due to the characteristics of the Hall element, There are drawbacks that the use conditions of the motor are limited or the motor is likely to fail.

Also, three Hall elements H _{1 to} H ₃ embedded in the stator 4
In order to take out the signal from the motor to the outside of the motor, a total of 12 lead wires per Hall element are required, and furthermore, three power supply lines are necessary to energize the stator 4. In order to control this kind of 3Φ electric motor, the operation of the electric motor cannot be performed sufficiently unless the electric power supply to the electric motor is controlled with 15 conductors.

For this reason, the terminals for connecting the electric motor and the lead wire are complicated, the positioning of the Hall element disposed in the stator, the accuracy control when the Hall element is fixed to the stator, or the connection of each element and device is performed. The disadvantage is that it is inevitable that the conductor connection management becomes complicated and that the Hall element itself is protected from oil, moisture, and other gas atmospheres in which the motor is installed, which limits the use of the motor. there were.

Further, the Hall element and other conventional detection sensors are fixed at a predetermined position predetermined according to the application of the electric motor, for example, the rotation speed of the drive or the magnitude of the load, and detect the rotation position of the rotor. Therefore, when this kind of motor is used for a load and a driving speed different from the sensor arrangement at the time of designing the motor, there is a disadvantage that it is difficult to obtain a highly efficient operation.

Further, in some DC motors, the operation control of the motor using the back electromotive force generated in the stator winding has been practiced for a long time. Since this is a macro control that compares the back electromotive force generated in proportion to the rotation speed and the reference voltage, the rotation control of the electric motor becomes a rough control, and the stator winding corresponding to the rotation position of the rotor is Since the power supply control is not performed, there is a gap from the optimal operation condition of the electric motor. Therefore, this type of conventional motor has to be designed to provide sufficient driving capability, and it has been difficult to reduce the size and thickness of the motor. In addition, in such an electric motor, substantial control cannot be performed until a back electromotive force generated in the stator winding becomes effective, and a special control circuit is required.

Furthermore, since no back electromotive force is generated when the motor is stopped, a separate starting circuit using no back electromotive force is required when starting the motor.

(C) Object In view of the foregoing, the present invention provides a control method that enables efficient operation of an electric motor from start to drive without using a Hall element or the like for detecting a rotational position of a rotor. It is intended for that purpose.

(D) Configuration That is, in the present invention, the rotational position of the rotor, particularly the state of this rotational position and the state of energization to the stator windings, are induced by the induced voltage generated in the stator side winding due to the rotation of the rotor. And setting the timing of energizing the next stator winding so that the magnitude of this difference matches the optimal operating conditions, and energizing the stator winding based on this set amount. When starting the motor before the rotor position can be obtained by the induced voltage, the stator must be controlled every time the ignition time elapses to determine the ignition timing for the stator windings. Switch the firing mode to the windings on the
The rotating magnetic field is obtained in the stator while the firing time is reduced according to the switching of the firing mode.

(E) Embodiment An embodiment in which the present invention is applied to a three-phase non-commutator DC motor shown in FIGS. 1 and 2 will be described below. Third
FIG. 1 is a drive control circuit diagram of a three-phase non-commutator motor embodying the present invention, and the same components as those in FIG. 1 are indicated by the same reference numerals. 3 is different from the conventional structure in that a control circuit 8 using a microcomputer is used for the control circuit 5 and a position detecting sensor such as a Hall element is omitted. Virtual neutral point A of the power supply voltage supplied to each phase and each phase U, V,
The point is that the induced voltage generated at W is compared by comparators CU, CV, and CW, and the electric motor is controlled by an electric signal obtained from the comparator.

Elements and components similar to those in FIG. 1 are used for the other parts, and the functions of the respective elements and components are substantially the same as those described with reference to FIGS. The part is simplified, and the details of the control method of the electric motor according to the present invention will be described below.

Rotor 7 having magnetism, such as a rotor having a permanent magnet
In the motor in which the rotor rotates, an induced voltage is generated in the stator windings U, V, and W.

This induced voltage is difficult to detect when the stator windings U, V, W are energized, but the stator of FIG. When controlling the energization of the winding, the virtual neutral point A described above is used.
And the rotor 7 between the non-energized phase stator windings.
Induced voltage in a specific direction corresponding to the rotational position of appears directly. Curves u, v, w shown in c, d of FIG. 2 schematically show voltages induced between the stator windings U, V, W and the virtual neutral point A in this way. The relationship between this waveform and the ignition mode for each stator winding U, V, W is as shown in the figure when the motor is in a steady operation state, and when the motor is started or the load on the motor increases. If the waveform of the induced voltage does not change the width of the horizontal axis in FIG. 2 because the rotation of the rotor 7 is delayed because the rotation of the rotor 7 cannot follow the conduction of the stator windings,
The state is later than the waveform indicated by the dotted line in FIG. 2d.

The present invention detects the rotational position of the rotor 7 using the induced voltages generated in the stator windings U, V, W in this manner, and determines the optimal firing in relation to the rotational state of the rotor 7. The output is given to the inverter 3.

That is, regarding the U phase of the timing chart (FIG. 2) showing the state of energization of the stator windings of the motor, etc.,
An intermediate point between the point where the second ignition mode ends and the point where the fourth ignition mode starts, in other words, the intermediate point E (in the figure) of the (third) ignition mode in which the U-phase is not energized. The direction of the induced voltage is reversed at around 150 ° on the scale, and similarly, the direction of the induced voltage is reversed at the midpoint F of the sixth firing mode (around 330 °). Thus, there is a certain relationship between the rotation angle of the rotor having magnetism and the induced voltage generated in the stator windings U, V, W due to this rotation.

The points E and F gradually move toward the second ignition mode (or the fifth ignition mode) when a load is applied to the rotor 7, and are applied to the rotor 7 when the electric motor is started. Since the load is large, the point E and the point F are set before the end of the second firing mode (or the fifth firing mode), for example, on the scale in the figure.
Since a difference occurs between the ignition mode and the actual rotation of the rotor 7 such as a change in the direction of the induced voltage at the position of 110 ° or 290 °, the control device 8 using the induced voltage as an input signal. By controlling the ignition timing and the optimal energizing time to the stator windings U, V, W, a highly practical motor can be obtained.

That is, when the induced voltage generated in the stator winding is not energized, the positive and negative differences in the induced voltage appear as they are in response to the increase and decrease of the magnetic field lines passing through the winding when the stator winding is not energized. If this change point (hereinafter, referred to as a potential direction change point) is detected by a suitable comparator such as a comparator, the rotation state of the rotor is detected in the same manner as a detection element such as a Hall element by a signal from the comparator. Can be detected.

For example, regarding the U phase, the potential direction change point is E
Point, is a point F, U-phase and 120 ° displacement V-phase disposed in the stator 4 is E ₁ point, F ₁ point, likewise U-phase and 240 ° offset W
In the phase, the potential direction change point can be detected at points E ₂ and F ₂ .

In the present invention, the calculation is performed based on the potential direction change point from each phase, and the timing of energization to each stator winding, in other words, switching of each mode and inverter 3
This is for controlling the power supply time to the power supply.

However, the rotor has inertia unless the load is excessively heavy, and it is not necessary to detect the rotor position every 60 ° rotation. Therefore, the apparatus is simplified and the potential direction change point is determined every 120 °. Even if a method for determining the timing of the ignition output to the inverter 3 is used, there is no practical problem.

When the load on the motor is sufficiently light, the potential direction change points at 360 °, that is, at each rotation of the rotor, are defined as U-phase, V-phase, and W-phase.
It is also possible to detect by one of the windings of the phase and control the inverter based on this signal. However, in the following description, each transistor Tr _{1 to} Tr ₆ constituting the inverter 3 is based on a potential direction change point appearing in any of the U phase, the V phase, and the W phase every 1/6 rotation (60 ° rotation). A description will be given of a case where ignition control is performed as a representative example.

In FIG. 3, terminals 11, 12, and 13 are terminals to which the stator windings U, V, and W are connected, and CU, CV, and CW are potentials based on the induced voltages generated in the stator windings U, V, and W. A comparator 15 detects a direction change point and supplies it to the input terminals I ₁ , I ₂ , I ₃ of the microcomputer 8 as a position signal of the rotor 7. A counter electromotive force 15 generated when the stator windings U, V, W are switched. From transistors Tr _{1 to} Tr ₆
Protection circuit for protecting the one end is connected to the base of the transistor _{Tr 1, Tr 2, Tr 3} , the other end to the output port O _1, O _2, O ₃ of the microcomputer 8 16 17 The connected inverting amplifiers, 25, 26 and 27 are connected to the output ports O ₄ , O ₅ and O ₆ of the microcomputer, and the transistors constituting the Darlington connection together with the transistors Tr ₄ , Tr ₅ and Tr ₆ , and 24 are the transistors 25 a power input to provide a base bias to the 26 and 27, the transistors Tr ₁ to Tr ₆ may output port O ₁ to O ₆
Are turned on in response to the H signal from.

Reference numeral 19 denotes a reset input terminal to the microcomputer 8, and reference numeral 20 denotes a clock signal input port for inputting an oscillation pulse from the vibrator 21 to the microcomputer 8 and controlling the inside.

The control by the control device having such a configuration will be described below with reference to a flowchart.

In the following description, T ₁ is the inversion time, T ₂ is recovery time, T ₃ is the waiting time. Each of these times changes momentarily depending on the time from the end of firing in the conduction mode to the detection of the position change point and the calculation result by the control device 8, but is common to each phase. Since this can be explained, this is shown in FIG.

In FIG. 4, the vertical axis is the voltage (hereinafter simply referred to as the positive direction) from the stator windings U, V, W of each phase to the neutral point N, and the lower axis is the same as in FIGS. From neutral point N to stator winding U,
The presence of current or voltage in the direction toward V and W (hereinafter simply referred to as the negative direction) is shown, and the horizontal axis is changed to the time axis display unlike the rotation angle display in FIGS. 2c and 2d. The rectangular wave A and the curve y show an enlarged main part of the relationship between the energized state of any one of the three phases U, V, and W and the induced voltage.

The characters of 120 ° and 60 ° written on the upper part indicate the energization of the rotating magnetic field excited by this winding for 120 ° rotation and the rotation of 60 ° for the stator winding regardless of the time axis scale. This shows that de-energization, reverse energization for 120-degree rotation, and non-energization at 60 degrees are repeated.

For example, referring to FIG. 4 taking the U phase as an example, I indicates that the current in the positive direction is applied to the U winding by the current in the first and second firing modes (the same applies hereinafter in FIG. 2). Then, the II winding is energized in the third firing mode, the U winding is paused for 60 degrees of magnetic field rotation, and then the magnetic field is energized in the fourth and fifth firing modes. The current flows in the negative direction for the time corresponding to the 120-degree rotation. III. The cycle in which the current returns to the first firing mode after repeating a pause for the same 60-degree rotation by energizing in the sixth firing mode is shown. ing.

And Thus, the waiting time T ₃ is a suitable waiting time is set in consideration of the synchronization between the rotational speed after the end rotor of the second ignition mode, because the rotation of the rotor is slow when the motor start , On the other hand, it is shortened for each rotation, and the standby time reaches zero when the rotation becomes steady.

If the standby time in the third ignition mode is 1 second, it takes at least 1 second for the rotation angle of the magnetic field to be less than 60 °, and the rotation speed of the magnetic field of the stator at this moment is about 1/6 rotation. This indicates that the motor is rotating at an extremely low speed of less than every second, in other words, less than 10 rpm.

Meanwhile, the T ₃ becomes zero indicates that the rotational speed of the electric motor is reversed time T ₁ and is determined only by recovery time T _2.

Then, after the output from the control device 8 is made so that the second firing mode is ended (or the third firing mode is fired), the inversion time T ₁ is changed to the U phase by the rotation of the rotor 7. Is the time until the induced voltage in the positive direction generated in the winding of the winding becomes zero (potential direction change point E), the starting point of time measurement is a signal from the control unit of the microcomputer itself, and the position direction change point is the comparator CU. since the output of the position signal to the input port I ₁ as the time becomes 0 H is sent, this time can be counted by the microcomputer built-in timer.

The U-phase restart time T ₂ is the time from when the input from the comparator UC changes from H to 0 to when the energization of the U-phase stator winding is started in the reverse direction. based on the inversion time T ₁ stored in the built-in register
And substantially calculates the same as T ₁ following times T ₂ and T ₁ has set this recovery time.

The above description of FIG. 4 has been made for the U-phase. Similarly, the inversion time T ₁ , the re-start time T ₂ , and the standby time T _{3 of} the V-phase and the W-phase are also changed for the stator winding and the comparator for each phase. The current is measured and set for each ignition mode by a timer or a calculation unit built in the microcomputer. The energization of each phase is performed in such a manner that the inversion time T _{1 of} each phase obtained in this manner is time Kakutenko each mode of T ₂ on the basis and can be set for each rotation of 60 degrees of the magnetic field of the stator in other words.

Further, the above description is based on the fact that the rotor
U-phase, V-phase, W-three stator windings time because the description of T ₁ to T ₃ on the basis of the six embodiments which receives the potential direction change points obtained using the phase for each rotation of the Is also set every 60 degrees of rotation.

In addition, the control of the rotation speed of the motor in the steady operation state
It suffices to shorten T ₁ and T ₂ , but as described above, T ₁
Timekeeping, when the set of T ₂ are, if increasing the force exerted by increasing the current flowing through the stator winding to the rotor of each cycle, the inversion time T ₁ is shortened, recovery time along with this T ₂
If the voltage applied to the stator winding is controlled, for example, the rotation speed of the motor can be automatically controlled.

Then, including the setting of the waiting time T _3, Figure 5 the relationship of the arc timing point of each mode from the start of the motor (a),
This will be described with reference to the flowchart of FIG.

In the register of the storage unit of the microcomputer,
A, B, and three registers C measurement and recovery time T ₂ of the inversion time T _1, is used to set the waiting time T _3. Each of these three registers A, B, and C has an appropriate number of bits, but in the following description, it will be simplified and described as a 4-bit register.

At the time of initial processing, the A register (standby time T ₃
ΦFH is given.

First, when the electric motor is started, the microcomputer 8 serving as a control device initializes each of the built-in A, B, and C registers and other parts (initial processing).

Next, a processing device (hereinafter simply referred to as a processing device) inside the microcomputer 8 outputs H from the output ports O ₁ and O ₅ so as to perform the output (OUT1) in the first firing mode in FIG.
A signal is output to turn on the transistors Tr ₁ and Tr ₅ , and a current flows from the winding U toward V to form a magnetic field in a fixed direction on the stator U.

The time for forming the magnetic field in such a direction (energization time) is continued for the time determined in the subroutine for timer processing (FIG. 5b). Time of this subroutine, the first ignition mode is intended to provide a waiting time T ₃ of the W-phase, since at start-up is given ΦFH by initial processing, T ₃ is timed based on the value . If the wait time T ₃ times out, the which a is started timer inversion time T ₁ at the same time, the time from the point in time until there is input from the comparator CW is timed and stored in the B register.

In this case, even leave actuates the timer T ₁ in which the rotor 7 does not rotate, the induced voltage is not generated in the stator windings. Processing apparatus is set at the time elapsed (time UP of T ₁ of the timer)
Thereafter, the elapsed time is stored in the B register without input from the comparator CW. Then, based on the value of the B register, after elapse inversion time T ₁ and substantially similar recovery time T ₂ (T ₂ timer start and T ₂ timer time UP), 1 from the value of the A register Subtraction, (T ₃ ← (T ₃ -1)),
Move to the second firing mode (OUT2).

Second ignition mode (OUT2) is arc condition changes point to the transistor Tr ₁ to Tr ₆ as compared with the first ignition mode, because the value of the A register is one less, waiting time T ₃ correspondingly Be shorter. When there is no position detection input, the reversal time T ₁ and the restart time T ₂ elapse as in the first firing mode, and the value of the A register is further reduced by 1 to move to the third firing mode (OUT3).

In the third firing mode (OUT3), the transistors Tr ₂ and Tr ₆ are fired as shown in FIG. The ignition time is the waiting time T ₃ determined by the value of A register is reduced for its value in the second ignition mode, calculated on the basis of inversion time T ₁ Toko inversion time determined by the signal coming from the comparator CU the time of the sum of the recovery time T ₂ that is determined by.

Therefore, the ignition time is the period from the first ignition mode to the third ignition mode, that is, until the position signal according to the potential direction change point is detected, it decreases with the decrease of the waiting time T ₃ I do.

As a matter of course, when the rotor 7 is rotated from the energization in the first ignition mode, the rotor that cannot be rotated by accident due to the position of the rotor 7 in the energization in the first ignition mode is also changed from the direction of the magnetic field at that time. 60 degrees or the second magnetic field which is rotated 120 degrees is formed, the third ignition mode is necessarily always rotor 7 starts to rotate, if the potential direction change points during measurement of the inversion time T _1, the inverted time T ₁ is timed as the time until the input from the comparator instead of time-up of the timer is stored in the B register.

In this way, after the standby time T ₃ and the standby time T ₃ are completed, the time measurement is started, the position is detected by the induced voltage of the stator winding, the inversion time T ₁ at which the time measurement is completed, and the value is calculated to be equal to or less than the value of T _1. energizing time obtained by summing the third ignition mode recovery time T ₂ to be set Te is made, and proceeds to the next fourth ignition mode (OUT4).

Before the transition to the ignition mode 4, the value of the A register becomes 1 again.
It goes without saying that it can be reduced.

In the fourth firing mode, the standby time T ₃ , the inversion time T ₁ , and the restart time T ₂ are set in the same manner as in the third firing mode, and then the fifth firing mode and the sixth firing mode are set. The cycle from the first firing mode to the sixth firing mode is repeated again, and the rotor 7 is driven.

According to the movement in the ignition mode, A
Register value stored in sequential, so will be reduced, the waiting time T _3, which is set by calculating based on the value of the A register is gradually shortened from the starting of the motor, the rotation of the rotor 7 constant By the time the rotation speed becomes, the value of the A register,
That is the waiting time T ₃ is zero.

In FIG. 4, the inversion time T ₁ when the standby time T ₃ is 0
The timer starts counting at the same time as the end of the second firing mode (the end of I), and the input of the potential direction change point at which the direction of the induced voltage generated in the stator winding due to the rotation of the rotor 7 changes from the comparator. counting is terminated with at point E is given to the microcomputer, the value T ₁ is stored in the B register. On the other hand, recovery time T ₂ are, for given by calculating the T ₁ as substantially equal T ₁ following time T ₁ based on, T _1, T ₂ are both shorter when the rotation of the rotor 7 is earlier, the load If the rotation of the rotor 7 is delayed due to the rotation, T ₁ and T ₂ become longer, the rotation speed of the magnetic field generated in the stator is reduced, and the operation is performed so as to reduce the deviation in rotation from the rotor. The energizing time (T ₁ + T ₂ ) in each mode is the time to give the rotating speed that balances the magnitude of the load on the rotor and the current flowing through the stator winding. Energized, 60
This cycle repeats a pause of a rotation of 120 degrees, a reverse energization of a rotation of 120 degrees, and a pause of 60 degrees.

The rotation angle cycle of the forward direction energization, pause, reverse direction energization, and pause for each phase is determined according to the amount of rotation of the rotor by a program stored in advance in the microcomputer. Arbitrarily selected,
It can be freely determined if the inverter 3 is controlled by a signal from the output port. In the case of the ignition control as in the present invention, as described above, the cycle of the 120 ° conduction and the 60 ° pause is used as described above. Operation of the motor with less third harmonics was realized.

(F) Effect As described above, in the motor control method of the present invention, the position state of the rotor is detected by the induced voltage generated in the winding on the stator side due to the rotation of the rotor, and the time until this detection is used as a basis. Since the energization time and energization timing to the stator windings are controlled by the output signals calculated in the above, a special position detecting element such as a conventional Hall element is not required, and the characteristics are maintained over the starting and driving of the motor. Good motor is obtained.

In addition, since the position detection element is not used, the number of lead wires connecting the motor and the control device can be reduced to a minimum of three wires. On the other hand, the energization time and timing of the winding depend on the amount of load applied to the rotor and the magnetic field generated by the winding. Is automatically determined by the strength of the motor, so that when the load is small, the motor can be driven at the same number of revolutions with small power consumption. Further, since the timer used for driving the electric motor can be used also for starting, a special starting circuit is not required. In addition, since a virtual neutral point is used, a lead wire for extracting a neutral point is not required.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of a commutatorless DC motor,
FIG. 2 is a timing chart, FIG. 3 is a circuit diagram showing an embodiment of a motor to which the method according to the present invention is applied,
FIG. 4 is an explanatory diagram of the ignition timing control, and FIG. 5 is a flowchart showing an example of the control according to the present invention, in which a is a main routine and b is a subroutine for a timer. 1 AC power supply 3 Inverter 4 Stator 7
... Rotor, 8 microcomputer, 9 position detection circuit.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-46309 (JP, A) JP-A-52-80415 (JP, A) JP-B-5-10039 (JP, B2)

Claims (1)

(57) [Claims] A rotor having magnetism and a plurality of Y-connected stator windings forming a rotating magnetic field for driving the rotor; The energization is controlled by using a plurality of ignition modes combined so that one phase in a non-energized state occurs, and the ignition modes are sequentially switched so that the rotor rotates, and time is measured by a timer. An output digitally computed by a microcomputer based on time and a position signal obtained when an induced voltage generated in a one-phase stator winding in a non-energized state due to rotation of the rotor reaches a predetermined set voltage. In the electric motor control method of controlling the switching timing of the ignition mode to obtain the rotating magnetic field, the position signal is generated in the one-phase stator winding in the non-energized state by the rotation of the rotor. Induced electricity Is a signal obtained when the virtual neutral point voltage corresponding to the neutral point of the Y-connected stator winding is reached, and when starting the motor before the position signal is obtained, the ignition time is The method of controlling a motor according to claim 1, wherein the ignition mode is sequentially switched at every elapse of time, and a rotating magnetic field is obtained in the stator while the ignition time is reduced according to the switching of the ignition mode.