JPH11341868A - Permanent magnet type synchronous motor and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce manufacturing cost and apparatus scale by enabling detec tion of potential phase at the stoppage, without the provision of a position detecting sensor for a rotary encoder and magnetic detecting element or the like. SOLUTION: This motor is provided with a motor 1 having a rotor which uses a permanent magnet and a stator including a winding and an inverter circuit 2 for switching supply and stop of supply of positive and negative currents to each winding. In addition, a permanent phase detection control circuit 3 is also provided, including a phase detecting circuit 3a for detecting the phases of rotor and stator, by detecting a voltage induced in each winding during the operation, a non-operating phase detecting circuit 3b for detecting the phase based on an back electromotive voltage during the non-operating time and a control circuit 3c for deciding operating and non-operating times, instructing cut-off condition after supply of a current for predetermined period to each winding, when the start command is issued to the inverter circuit 2 during the non-operating times and also instructing supply or cutoff of current based on the phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a permanent magnet type synchronous motor and a control method thereof. A permanent magnet type synchronous motor has a property that it can rotate only at a synchronous speed.
Therefore, it is necessary to detect the phases of the rotor (rotor) and the stator (stator) to determine the timing for exciting the windings (coils) of the stator.

[0002]

2. Description of the Related Art Conventionally, there are two methods for detecting the phases of a rotor and a stator. The first method uses a position detector (rotary encoder, magnetic detection element, etc.) for the rotor.
The second method is to detect the position by an induced voltage generated when the rotor is rotating.

[0003]

However, the method of detecting a position by attaching a position detector to the rotor as in the former method increases the manufacturing cost of the electric motor because a position detector is required. At the same time, the device scale of the electric motor is increased. Also, the position detector
When the rotation speed becomes high, the reliability or the response is deteriorated, and the wiring is increased to provide the position detector, so that the reliability is deteriorated. In addition, there are various problems that the number of steps for mounting the position detector increases, and the manufacturing is troublesome.

On the other hand, the method of detecting the induced voltage by the rotation of the rotor is that when the rotor is stopped, the induced voltage cannot be detected, so that the conductive machine cannot be driven smoothly from the stopped state. Had problems. Under such circumstances, it has been usual to use an expensive and large-sized motor equipped with a position detector.

Therefore, an object of the present invention is to solve the above-mentioned problems in the conventional technology.
It is possible to detect the phase between the rotor and the stator at the time of stoppage without installing a new sensor for position detection such as a rotary encoder and a magnetic detection element. It is an object of the present invention to provide a permanent magnet type synchronous motor having good reliability and responsiveness without increasing power consumption and a control method thereof.

[0006]

SUMMARY OF THE INVENTION In order to solve the above technical problems, a first invention is to provide an electric motor 1 having a rotor using a permanent magnet and a stator provided with windings, and each winding. An inverter circuit 2 for switching between supply and cutoff of positive and negative currents to the motor 1, and determining whether the motor 1 is operating or stopped,
At the time of operation, the phase between the rotor and the stator is detected based on the induced voltage induced at each winding, and at the time of stoppage, the inverter circuit 2 shuts off after supplying a current for a predetermined time to each winding. And a constant phase detection control circuit 3 for detecting the phase based on the back electromotive force generated in the winding and instructing the inverter circuit 2 to supply or cut off the current to each winding according to the phase. Things.

Here, for phase detection, the current supplied to each winding at the time of stoppage is either positive or negative current and has the same waveform in order to facilitate the structure and analysis. Is preferably supplied for a predetermined period of time.
"Instruct the inverter circuit 2 to supply or cut off the current according to the phase" is to rotate the rotor at a synchronous speed or the like during operation, and to
By exciting the winding to the winding position closest to the rotor pole and pulling the rotor and starting the initial state from a fixed position, the rotation frequency is increased, and a smooth transition to synchronous speed control is achieved. That's why.

According to the present invention, when it is determined that the motor 1 is stopped when no induced voltage (induction voltage) is detected on the winding, and when there is a command to start the motor 1 from the stopped state, the phase detection control means 3 always operates. By controlling the switching of the inverter circuit 2, a positive or negative current is preferably caused to flow through each winding (coil) for a certain period of time. When a current flows through the winding, a magnetic flux is generated in the winding and stored as magnetic energy in the winding. This stored magnetic energy depends on the inductance of the winding. The inductance of a winding is determined by the total number of interlinking magnetic fluxes when a current flows through the winding, and is determined by the relative positions of the rotor and the stator.

When the current is supplied and then shut off, the stored magnetic energy changes to electric energy and a back electromotive voltage is generated in the winding. The stored magnetic energy amount is discharged as it is as an electric energy amount called a back electromotive voltage. Therefore, the inductance value of the winding can be indirectly known by detecting the amount of the back electromotive voltage. Further, the inductance value of the winding has a relationship that changes depending on the phases of the rotor and the stator.

Therefore, the phases of the rotor and the stator can be determined by measuring the amount of back electromotive voltage generated by supplying a current to each winding and cutting off the current without directly measuring the inductance value. . The present invention uses this principle.

According to a second aspect of the present invention, as shown in the circuit block diagram of FIG. 1, in the first aspect, the constant phase detection control circuit operates based on an induced voltage induced in each winding of the stator during operation. A phase detecting circuit 3a for detecting the phase, a phase detecting circuit 3b for detecting the phase based on the back electromotive force at the time of stop, a determination of operation and a stop, and a stop for the inverter circuit 2. And a control circuit 3c for instructing a cutoff after a current is supplied to each winding for a predetermined time when a start command is given at the time, and a current supply or cutoff based on the phase. .

In a third aspect based on the second aspect, the constant phase detection control circuit has switching means for switching connection and disconnection between a neutral point of each winding and a ground voltage,
The control circuit connects the neutral point to the ground voltage by the switching means, supplies current to all the windings simultaneously for a predetermined time, and then applies a counter electromotive voltage generated by cutting off to the stop-time phase detection circuit. Is what you do.

According to the present invention, the switching means is provided, and the neutral point of the winding is switched to the ground voltage by the switching means, so that a current flows simultaneously through the windings of each phase for a predetermined time. By cutting off the neutral point from the ground voltage, the current can be cut off and the phase can be quickly detected in a short time.

In a fourth aspect based on the second aspect, the control circuit of the constant phase detection control circuit supplies a current to each of the windings to the inverter circuit sequentially for a predetermined time while shifting the time. The back electromotive voltage generated after the interruption is sequentially applied to the phase detection circuit at the time of stop.

According to the present invention, a back electromotive voltage is generated with a time lag by sequentially controlling the timing and supplying a current with a time lag to the windings of each phase and then shutting off the current. The phase at the time of stop can be detected without using a switching means for switching the voltage at the neutral point.

According to a fifth aspect of the present invention, there is provided a motor comprising a rotor using a permanent magnet and a stator provided with a winding, a step of determining whether or not the motor is stopped; If determined, a step of supplying a current to each winding for a predetermined time and then shutting off; a step of detecting a phase at the time of stopping based on a back electromotive voltage generated for each winding; and Controlling the activation from the stop.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a permanent magnet type synchronous motor and a control method thereof according to the present invention will be described with reference to FIGS. This embodiment does not limit the present invention unless otherwise specified.

FIGS. 2 to 9 show a permanent magnet type synchronous motor system according to the first embodiment. As shown in FIG. 2, the permanent magnet type synchronous motor includes a two-pole rotor (rotor) 14 using permanent magnets and a stator (stator) provided with three-phase windings 11, 12, and 13. It has an electric motor 10 and an inverter circuit 20 for switching between supply and cutoff of positive and negative DC current to each winding of the stator. In order to supply a positive or negative DC current to the inverter circuit 20, a three-phase AC power supply 40, a converter 50 for changing an AC current to a DC current for each phase using a diode or the like, and rectification by the converter 50 And a smoothing capacitor 60 for smoothing the waveform of the obtained current.

The inverter circuit 20 comprises six transistors + W, -W, + V, -V, + U,-
U is a switching element for supplying and interrupting a positive or negative current to the W-phase winding 13, the V-phase winding 12, and the U-phase winding 11, respectively. As shown in FIG. 2, these transistors are provided so as to form a pair of transistors each having an emitter and a collector connected to each other.
1, 12, and 13. The inverter circuit 20 further includes a drive circuit 25 that outputs an on or off signal according to an instruction at the base of each transistor.

In order to cause each transistor to perform a switching operation at a predetermined cycle and rotate the rotor 14 at a predetermined synchronous speed, in each transistor pair, an ON signal is applied to the base of one transistor and to the other transistor. An off signal is applied to excite the windings of a certain phase to rotate the rotor 1
After pulling in 4, the off signal is applied to the base of one of the transistors and the on signal is applied to the other transistor to excite the winding in the opposite direction to pull the rotor 14 away from the position and to turn on the next phase. The winding performs the control to draw the rotor 14 at the synchronous speed.

The permanent magnet type synchronous motor according to the present embodiment is capable of detecting the phase between the rotor and the winding with respect to the inverter circuit 20 at all times irrespective of the time of stop and operation. It has a constant phase detection control circuit 30 that can instruct the timing of current supply and cutoff based on the phase.

As shown in FIG. 2, in detail, the constant phase detection control circuit 30 detects the induced voltage induced in the stator windings 11, 12, and 13 of the electric motor 10 at the time of operation, thereby operating the motor. Phase detection circuit 31 for detecting the phase of the rotor at the time, a phase detection circuit for stoppage 32 for detecting the phase based on the back electromotive force at the time of stoppage, a determination at the time of operation and stoppage of the electric motor 10, and an inverter When a start command is issued to the circuit 20 when the circuit 20 is stopped, a cutoff instruction is supplied after a positive or negative current is supplied to each winding for a predetermined time (here, for example, t seconds), and based on the phase. Control circuit 33 for instructing supply or cutoff of positive or negative current
And

The constant phase detection control circuit 30 further comprises:
A voltage dividing circuit 34 for dividing the output signal of the inverter circuit 20 to obtain an appropriate voltage value and applying the divided voltage to each terminal of the phase detection circuit 31 and the stop-time phase detection circuit 32; Connection and disconnection of point 15 and ground voltage
There is provided switching means 35 using a relay or the like that switches according to an instruction from the control circuit 33.

Next, the stop-time phase detection circuit 32 will be described with reference to FIG. The stop-time phase detection circuit 3
2 has hold circuits 75u, 75v, and 75w that hold back electromotive voltages from the U-phase, V-phase, and W-phase windings 11, 12, and 13 and output the signals in response to signals from the timing circuit 76. The stop-time phase detection circuit 32 includes the rotor 1
In order to detect the maximum or minimum counter-electromotive voltage generated when the N or S pole of No. 4 is closest to the stator winding, a predetermined maximum reference voltage (MAX reference voltage) and a predetermined minimum reference voltage (MIN) are detected. A comparison circuit (comparator) 71u, 72u, 71v, which outputs a signal of 1 or 0 according to the magnitude of the reference voltage) and the back electromotive voltage generated in each winding.
72v, 71w, and 72w. Further, the stop-time phase detection circuit 32 compares the back electromotive voltages generated in the windings of each phase with each other, and outputs a 1 or 0 signal according to the magnitude of the back electromotive force. The comparison circuits 73u, 74u, 73v, 74v, 73w, 7
4w. Further, the stop-time phase detection circuit 32
A logic circuit 77 for detecting a stop phase based on signals output from each of these comparison circuits and transmitting a signal corresponding to the corresponding phase to the control circuit 33 in accordance with a signal from the timing circuit 76; 33 and the hold circuits 75u, 75v, 75
timing circuit 76 for instructing w to output timing
And

Subsequently, based on FIGS. 4 to 9,
The operation of the permanent magnet type synchronous motor according to the first embodiment will be described. During the operation of the permanent magnet type synchronous motor rotating in the free-run state, an induced voltage is generated, so that the phase can be detected by the phase detection circuit 31 based on the induced voltage.

In the stop state, since no induced voltage is generated, the phase detection circuit 31 cannot detect the phase. When the induced voltage is not detected by the phase detection circuit 31, the control circuit 33 determines that the rotor 14 is stopped. When the control circuit 33 receives a start command from the outside in the stop state, the control circuit 33
And a mode to detect the phase of the stator.

Next, the phase detection mode of the stopped rotor and stator will be described. As shown in FIG. 4, to detect the phase between the rotor 14 and the stator at the time of stop, the control circuit 3
3 turns on the W-phase positive current transistor + W, the V-phase positive current transistor + V and the U-phase positive current transistor + U of the inverter circuit 20, and turns on the W-phase negative current transistor-. The drive circuit 25 is instructed to turn off the W- and V-phase negative current transistor-V and the U-phase negative current transistor-U. At the same time, the control circuit 33 controls the neutral point 15
Is connected to the ground voltage, so that the U-phase winding 1
1. A positive current is simultaneously applied to each of the V-phase winding 12 and the W-phase winding 13 for a predetermined time (t seconds). Thereby, each winding 1
Magnetic energy that depends on the inductance corresponding to the phase between the rotor 14 and the stator is stored in 1, 12, and 13, respectively. After a certain period of time, the control circuit 33 cuts off the current by switching the transistor from the on state to the off state. Then, the magnetic energy stored in each of the windings 11, 12, and 13 generates a back electromotive voltage as shown in the lower part of FIG. 4, and the voltage is divided by the voltage dividing circuit 34 for each of the windings. It is applied to each terminal of the phase detection circuit 32.

As shown in FIG. 3, the divided back electromotive voltages of the windings of each phase are stored in hold circuits 75u, 75v and 75w, respectively, and are simultaneously supplied to respective comparison circuits 71u and 71v in accordance with an instruction from timing circuit 76. , 71w, 72u, 72
v, 72w, 73u, 73v, 73w, 74u, 74
v, 74w, and as shown in the phase examples of FIGS. 5, 6, and 7, judgment patterns corresponding to various voltage values corresponding to the phases of the rotor 14 and each winding are input to the logic circuit 77. I do. The logic circuit 77 determines which of the phases shown in Examples 1 to 12 of FIG. 5, FIG. 6, or FIG. 7 according to each determination pattern as shown in the table of FIG. A corresponding signal is sent to the control circuit 33.

Here, for example, when it is indicated that the comparison result of the comparison circuit 71u, the comparison circuit 71v, or the comparison circuit 71w is higher than the MAX reference voltage, the comparison result is not limited to the MAX reference voltage. It is determined that the N pole is closest to the winding of the phase in which the voltage higher than the voltage is detected. That is, in the case of the U phase, a signal representing a phase corresponding to Example 1 in FIG. 5, in the case of the V phase, Example 3 in FIG. 5, and in the case of the W phase, a signal representing a phase corresponding to Example 5 in FIG. Output from the circuit 77.

Similarly, a comparison circuit 72u, a comparison circuit 72
v. If it is indicated that the comparison result of the comparison circuit 72w is smaller than the MIN reference voltage, the S-pole is applied to the winding of the phase in which the voltage smaller than the MIN reference voltage is detected regardless of the other comparison results. Is determined to be closest. That is,
In the case of the U phase, it is determined to be Example 7 in FIG. 6, in the case of the V phase, it is determined to be Example 9 in FIG. 7, and in the case of the W phase, it is determined to be Example 11 in FIG.

In other cases, the U-phase voltage is
When the voltage of the phase is represented by V and the voltage of the W phase is represented by W, for example, in Example 2 in FIG. 5, the voltage becomes U = V> W from the phases of the rotor and the stator. In this case, the output of each comparison circuit is that the comparison circuits 73u and 74u for the U phase
V, it is uncertain and NO and NO respectively.
Since v> W, v> 74v is YES, NO, and the comparison circuits 73w, 74w, and W <U, NO, Y
ES. Since each voltage is neither the maximum voltage nor the minimum voltage, the comparison circuits 71u, 72u, 71v, 72
The output results of v, 71w, and 72w are also NO. If the output result of NO is “0” and the output result of YES is “1”, a determination pattern of “0001001010” is obtained. Similarly, the judgment patterns corresponding to the respective examples of FIGS. 5, 6, and 7 are obtained as shown in the table of FIG. The determination pattern is converted by the logic circuit 77 into a signal of six digits of phase information representing the phase at the time of stop, and is sent from the logic circuit 77 to the control circuit 33 in accordance with a signal from the timing circuit 76.

In this way, the control circuit 33 enters a start-up mode from stop based on the detected phase information. Next, a startup mode from stop will be described. When receiving the phase information from the logic circuit 77, the control circuit 33 performs the pull-in excitation control based on the phase information.
The pull-in excitation control is an operation of pulling the rotor position to a predetermined winding position of the stator as an initial state in order to start the electric motor 10.

For example, as shown in FIG.
4 and the phases of the windings 11, 12, and 13 of the stator 16 are detected, in order to pull the position of the rotor 14 up to the determined winding position of the stator 16, + U
The control circuit 33 instructs the inverter circuit 20 to excite the S pole in the phase and the N pole in the -U phase.

The phases of the rotor 14 and the stator 16 are shown in FIG.
When the home position is reached as shown in (b), a timer switching mode for automatically increasing the rotation frequency is entered. When the rotation speed increases and the level of the induced voltage from the electric motor 1 increases and the position can be detected, the switching timing is performed based on the position information detected by the phase detection circuit 31.

As described above, in the present embodiment,
By applying a current to the windings 11, 12, and 13 all at once for a certain period of time and then cutting off, the back electromotive voltage can be simultaneously and simultaneously detected for each phase. In particular, when the number of phases increases, the time from the start command to the start of the operation is shortened, and the responsiveness increases.

Next, a permanent magnet synchronous motor according to a second embodiment will be described with reference to FIGS. The same reference numerals as those in FIGS. 2 to 4 according to the first embodiment denote the same components. As shown in FIG. 10, the constant phase detection control circuit 36 according to the present embodiment
As in the case of the first embodiment, the phase detection circuit 3
1; the stop-time phase detection circuit 32;
And 4. However, unlike the first embodiment, the constant phase detection control circuit 36 is provided with switching means 35 for switching connection and disconnection between the neutral point of each phase winding of the stator and the ground voltage. Not. Therefore, the control circuit 38 also differs from the control circuit 33 according to the first embodiment in that there is no instruction to the switching means 35.

Next, the operation of the permanent magnet type synchronous motor according to the present embodiment will be described with reference to FIG.
During the operation in which the permanent magnet synchronous motor is rotating in the free-run state, an induced voltage is generated and the phase can be detected by the phase detection circuit 31, as in the first embodiment.

When the motor 10 is stopped, no induced voltage is generated, so that the phase detection circuit 31 cannot detect the phase. When the induced voltage is not detected by the phase detection circuit 31, the control circuit 38 determines that the operation is stopped. When there is a start command in the control circuit 38, a mode is entered in which the phase between the rotor 14 and the stator is detected.

Next, the phase detection mode of the stationary rotor and stator will be described. As shown in FIG. 11, in order to detect the phase between the rotor 14 and the stator at the time of stop, first,
By turning ON only the positive current transistor + U and the negative current transistor -W and the transistor -V of the inverter circuit 20, a positive current flows through the U-phase winding 11 for a certain period of time. Thus, the U-phase winding 11
Then, magnetic energy depending on the inductance corresponding to the phase between the rotor 14 and the stator is accumulated. After a certain period of time, the transistor that has been turned on is turned off to cut off the current. Then, the magnetic energy stored in the U-phase winding 11 generates a back electromotive voltage as shown in the lower part of FIG. 11, and the voltage is transmitted through the voltage dividing circuit 34 to the U-phase of the stop-time phase detecting circuit 32. Applied to phase terminals.

Next, in order to pass a positive current through the V-phase winding,
By turning on only the positive current transistor + V and the negative current transistor -U and the transistor -W of the inverter circuit 20, the V-phase winding 12
Current for a certain period of time. Thereby, the V-phase winding 12
Then, magnetic energy depending on the inductance determined according to the phase between the rotor 14 and the stator is accumulated. After a certain period of time, the transistor that has been turned on is turned off to cut off the current. Then, the magnetic energy accumulated in the V-phase winding 12 generates a back electromotive voltage as shown in the second stage below in FIG. To the V-phase terminal.

Subsequently, in order to supply a current to the W-phase winding,
Only the transistor + W, the transistor -U, and the transistor -V are turned on, and a current flows through the W-phase winding 13 for a certain time. As a result, the U-phase winding 13
Magnetic energy is accumulated based on the inductance determined according to the phase between the rotor 14 and the stator. After a certain period of time, the transistor that has been turned on is turned off and the current is cut off. Then, the magnetic energy accumulated in the W-phase winding 13 is converted into a back electromotive voltage as shown in the lower third stage of FIG. Applied to W-phase terminal.

Each back electromotive voltage input to the stop-time phase detection circuit 32 is sequentially held in the hold circuits 75u, 75v, and 75w, and finally, when there is a signal of the timing circuit 76 in synchronization with the W-phase input. Each counter electromotive voltage is applied to a comparison circuit 71u, 7
1v, 71w, 72u, 72v, 72w, 73u, 73
v, 73w, 74u, 74v, and 74w, and compared as described in the first embodiment. The comparison result is input to the logic circuit 77, and the corresponding phase information is input by a signal from the timing circuit 76. To the control circuit 38. The control circuit 38 enters the start mode from the stop based on the detected phase information in this way. The start mode from stop is the same as that described in the first embodiment.

As described above, according to the present embodiment, the switching means 35 is not required as compared with the first embodiment, and therefore, the conducting wire connecting the neutral point of the motor to the switching means is provided. Since no current is required, a current can be applied to the winding by controlling the on and off of the existing transistor, so that the number of parts is small and the structure is relatively simple.

These embodiments are specifically described for better understanding of the present invention, and do not limit another embodiment. Therefore, it can be changed without changing the gist of the invention. For example, although a permanent magnet synchronous motor has been described in the above description, a permanent magnet may be replaced with an electromagnet. Also,
In the above description, the case of two poles and three phases has been described. However, the present invention is not limited to these, and other pole numbers and other phase numbers can be easily applied. In addition, the current supplied to detect the phase at the time of stoppage is
The current is not limited to the positive current, and may be a negative current. The switching element provided in the inverter circuit is not limited to a transistor. Further, the stop-time phase detection circuit is not limited to the above-described circuit, and may be various types. For example, it is possible to specify the phase more finely.

[0045]

As described above, according to the first invention or the fifth invention, even when the rotor is stopped, the current is supplied to the winding for a predetermined time and then shut off. The phase at the time of stoppage can be detected based on the back electromotive voltage generated by this. Therefore, according to the present invention, the rotary
It is possible to detect a phase at a stop without providing a position detector such as an encoder, a resolver, and a magnetic detection element in a rotor. Therefore, it is possible to reduce the manufacturing cost of the permanent magnet type synchronous motor and reduce the size of the device.

According to the second invention, the constant phase detection control circuit has a phase detection circuit during operation and a phase detection circuit during stoppage. Therefore, since the existing phase detection circuit can be used for detecting the phase during operation, the manufacturing cost can be reduced accordingly.

According to the third aspect of the present invention, the constant phase detection control circuit is provided with switching means for switching connection and disconnection between the neutral point of each phase winding and the ground voltage so that the windings of each phase are simultaneously connected to the windings of each phase. The phase at the time of stop is detected based on the back electromotive voltage generated by interrupting after supplying the current. Therefore, at the time of stop, the back electromotive voltage generated by simultaneously supplying and interrupting the current to the windings of each phase can be detected, so that the time from the start command to the start of operation can be reduced. High responsiveness as possible.

According to the fourth aspect of the present invention, the constant phase detection control circuit interrupts the current supplied to the winding of each phase of the stator by sequentially shifting the time by the switching control of the inverter circuit. The phase at the time of stop is detected based on the generated back electromotive voltage. Therefore,
By using an existing circuit and sequentially supplying current to the windings of each phase, it is possible to detect the phase at the time of stoppage, so the number of components can be reduced with a simple configuration, and the manufacturing cost can be reduced. Can be.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of the present invention.

FIG. 2 is a circuit diagram showing a permanent magnet type synchronous motor according to the first embodiment.

FIG. 3 is a diagram showing a stop-time phase detection circuit according to the first embodiment;

FIG. 4 is an operation explanatory diagram of the permanent magnet type synchronous motor according to the first embodiment.

FIG. 5 is a phase explanatory view of the permanent magnet type synchronous motor according to the first embodiment.

FIG. 6 is a phase explanatory view of the permanent magnet type synchronous motor according to the first embodiment.

FIG. 7 is a phase explanatory view of the permanent magnet type synchronous motor according to the first embodiment.

FIG. 8 is a diagram showing a determination pattern according to the first embodiment;

FIG. 9 is an explanatory drawing of a retracting operation of the permanent magnet type synchronous motor according to the first embodiment.

FIG. 10 is a circuit diagram of a permanent magnet synchronous motor according to a second embodiment.

FIG. 11 is an explanatory diagram of an operation of the permanent magnet type synchronous motor according to the second embodiment.

[Explanation of symbols]

 1, 10 Motor 11, 12, 13 Windings 14 Rotor 2, 20 Inverter circuit + U, + V, + W, -U, -V, -W Transistor 3, 30, 36 Phase detection control circuit 3a, 31 Phase detection circuit 3b, 32 Stop phase detection circuit 3c, 33, 38 Control circuit 34 Voltage divider 35 Switching means 40 Three-phase AC power supply 50 Converter circuit 60 Smoothing circuit 71, 72, 73, 74 Comparison circuit (comparator) 75 Hold circuit 76 Timing Circuit 77 Logic circuit

Claims (5)

[Claims] An electric motor (1) having a rotor using a permanent magnet and a stator provided with windings, and an inverter circuit (2) for switching between supply and cutoff of positive and negative currents to and from each winding.
And determining whether the motor (1) is operating or stopped,
In operation, the phase between the rotor and the stator is detected based on the induced voltage induced in each winding, and when stopped, the inverter circuit (2) cuts off the current after supplying current to each winding for a predetermined time. And a constant phase detection control circuit (3) for instructing the inverter circuit (2) to detect the phase based on the back electromotive voltage generated in the winding and instruct the supply or cutoff of the current according to the phase. A permanent magnet synchronous motor characterized by having: 2. A constant phase detection control circuit comprising: a phase detection circuit for detecting the phase based on an induced voltage induced in each winding of the stator during operation; A phase detection circuit (3b) for detecting the phase based on the phase, a judgment of operation and a stop, and a predetermined command for each winding when a start command is issued to the inverter circuit (2) at the time of the stop. Instruction of time current supply; and
The permanent magnet type synchronous motor according to claim 1, further comprising a control circuit (3c) for instructing supply or cutoff of a current based on the phase. 3. The constant phase detection control circuit has switching means for switching connection / disconnection between a neutral point of each winding and a ground voltage, and the control circuit sets the neutral point to ground by the switching means. 3. The permanent magnet type synchronous circuit according to claim 2, wherein a counter electromotive voltage generated by shutting off after supplying current to all windings simultaneously for a predetermined time by being connected to a voltage is applied to the stop-time phase detection circuit. Electric motor. 4. The control circuit of the constant phase detection control circuit supplies a current to each of the windings for a predetermined time by sequentially shifting the time to the inverter circuit, and then generates a back electromotive force generated by cutting off the current. Are sequentially applied to the stop phase detection circuit. 5. A step of determining whether or not an electric motor is stopped for an electric motor including a rotor using a permanent magnet and a stator with windings, and a case where it is determined that the electric motor is stopped. A step of supplying a current to each winding for a predetermined time and then shutting off; a step of detecting a phase at the time of stopping based on a back electromotive voltage generated for each winding; and starting from a stop based on the phase. Controlling the permanent magnet type synchronous motor.