JP2007174721A - Apparatus and method for detecting initial rotational position in brushless dc motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately find a rotational position (a stopped electric angle) of a rotor in a magnet embedded brushless DC motor without a sensor. <P>SOLUTION: When the rotor in the IPM motor is stopped, a current for magnetically saturating a winding flows, and positive phase currents Iu, Iv, Iw and negative phase currents Iu(N), Iv(N), Iw(N) are found. Intervals I-III are determined by determining the maximum among the phase currents Iu, Iv, Iw. In the determined zones, the rotational position of the rotor is determined based on the degree of deviation of "a difference between the maximum phase current and the second-maximum phase current" and "a difference between the second-maximum phase current and the minimum phase current" among the phase currents Iu, Iv, Iw. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an initial rotational position detection device and an initial rotational position detection method for a brushless DC motor, and is devised so that the rotational position (electrical angle) of a stopped rotor can be accurately and easily detected without a sensor. Is.

A brushless DC motor is a motor that uses a semiconductor element to switch energization without using a brush.
There are two types of brushless DC motors: the surface magnet type (Surface Permanent Magnet type: SPM type) with a permanent magnet attached to the rotor surface, and the interior magnet type (Interior Permanent Magnet type) with a permanent magnet embedded in the rotor core. : IPM type).

  In a brushless DC motor, in order to obtain a starting torque at the time of starting, the rotational position (electrical angle) of the rotor is detected, and a three-phase current having a phase corresponding to the rotational position is supplied to the three-phase winding of the stator. There must be.

  As a method for detecting the rotational position of the rotor, there are a method using a sensor and a method for estimating the rotational position of the rotor by measuring the inductance characteristics of the stator winding without using the sensor.

  In the method using a sensor, for example, a rotational position is detected using a resolver or a Z-phase encoder. However, the use of the sensor increases the number of parts, resulting in an increase in cost.

  The method of estimating the rotational position of the rotor by measuring the inductance characteristics of the stator winding is applied to an IPM type brushless DC motor.

  In the IPM type brushless DC motor, as shown in FIG. 7 which is a schematic configuration diagram, a rotor 2 is disposed inside a stator 1 via an air gap. The stator core of the stator 1 is provided with a three-phase stator winding (not shown). A plurality of permanent magnets 4 are embedded in the rotor core 3 of the rotor 2.

When the circumferential surface of the rotor core 3 is traced in the circumferential direction, “the portion where the S-pole permanent magnet is embedded” → “the portion where the permanent magnet is not embedded” → “the N-pole permanent magnet is embedded. The portion changes cyclically, such as “part” → “part in which no permanent magnet is embedded” → “part in which an S-pole permanent magnet is embedded”.
For this reason, since the magnetic resistance changes according to the rotational position of the rotor 2, the inductance characteristics of the stator windings change. Therefore, the rotational position of the rotor 2 can be detected by measuring the inductance of the stator winding.

  Here, a conventional method for detecting the rotational position of the rotor of the IPM type brushless DC motor by measuring the inductance characteristic of the stator winding will be described.

FIG. 8 shows the initial rotational position estimated current characteristics in an IPM type brushless DC motor. The horizontal axis represents the rotational position (electrical angle) of the rotor, and the vertical axis represents the U-phase current Iu, the V-phase current Iv, W phase current Iw is shown.
This initial rotational position estimation current characteristic is such that when the rotor of the IPM type brushless DC motor is stopped at each electrical angle, a pulse voltage is applied for a short time and a current of “not magnetically saturated” flows. The characteristic of each phase current value (value of U phase current Iu, value of V phase current Iv, value of W phase current Iw) at each electrical angle is shown.

here,
・ "U-phase current Iu" means a short time between the external terminal of the U-phase winding and the external terminal of the V- and W-phase windings (the terminal sharing the external terminals of the V- and W-phase windings). This is the current that flows through the U-phase winding by applying a pulse voltage only.
・ "V-phase current Iv" means a short time between the external terminal of the V-phase winding and the external terminal of the W and U-phase windings (the terminal sharing the external terminals of the W and U-phase windings). This is the current that flows through the V-phase winding by applying a pulse voltage only.
・ "W-phase current Iw" means a short time between the external terminal of the W-phase winding and the external terminal of the U and V-phase windings (the terminal sharing the external terminals of the U and V-phase windings). This is the current that flows through the W-phase winding by applying a pulse voltage only.

From the characteristics of FIG. 8, it can be determined that the state is substantially the following.
(1) The section in which the U-phase current Iu is larger than the V-phase current Iv and the W-phase current Iw
When the electrical angle is 60 ° to 90 ° (this is referred to as “Section A1”),
When the electrical angle is 90 ° to 120 ° (this is referred to as “Section A2”),
When the electrical angle is 240 ° to 270 °, that is, when the electrical angle is advanced by 180 ° from the section A1 (this is referred to as “section A3”),
When the electrical angle is 270 ° to 300 °, that is, when the electrical angle is advanced 180 ° from the section A2 (this is referred to as “section A4”).

(2) The section in which the V-phase current Iv is larger than the W-phase current Iw and the U-phase current Iu
When the electrical angle is 180 ° to 210 ° (this is referred to as “Section B1”),
When the electrical angle is 210 ° to 240 ° (this is referred to as “Section B2”),
When the electrical angle is 360 ° (= 0 °) to 390 ° (= 30 °), that is, when the electric angle is advanced by 180 ° from the section B1 (this is referred to as “section B3”).
When the electrical angle is 390 ° (= 30 °) to 420 ° (= 60 °), that is, when the electric angle is advanced by 180 ° from the section B2 (this is referred to as “section B4”).

(3) The section in which the W-phase current Iw is larger than the U-phase current Iu and the V-phase current Iv
When the electrical angle is 300 ° to 330 ° (this is referred to as “section C1”),
When the electrical angle is 330 ° to 360 ° (this is referred to as “section C2”),
When the electrical angle is 120 ° to 150 °, that is, when the electrical angle is advanced 180 ° from the section C1 (this is referred to as “section C3”),
When the electrical angle is 150 ° to 180 °, that is, when the electrical angle is advanced by 180 ° from the section C2 (this is referred to as “section C4”).

  Conventionally, the rotational position (electrical angle) of the stopped rotor is obtained based on the characteristics shown in FIG. That is, by comparing the phase currents Iu, Iv, and Iw, it is determined which of the 12 sections of the sections A1 to A4, B1 to B4, and C1 to C4 is included in the rotational position (electrical angle) θ. is doing.

A specific method of determination is shown in FIG.
First, in step 1 (S1), a pulse voltage of + 100% duty is applied for three control periods, and each phase current Iu, Iv, Iw is measured. Each phase current flowing at this time becomes a current having a value equal to or less than the rated current without saturating the winding.

Here, “one control cycle” is a control cycle for controlling the current value of the current supplied from the inverter device to the motor, and for example, one control cycle is 125 μsec.
Also, “+ 100% duty”
For U-phase current, the U-phase winding side is set to a positive voltage, the V and W-phase winding sides are set to a negative voltage (meaning “+”),
For V-phase current, the V-phase winding side is set to a positive voltage, the W and U-phase winding sides are set to a negative voltage (meaning “+”),
If it is a W-phase current, the W-phase winding side is a positive voltage, the U and V-phase winding sides are a negative voltage (meaning “+”),
Applying a voltage (for example, 80V) having a duty of 100% of the voltage value (for example, 80V) of the power supply voltage (meaning “100% duty”).

  In steps S2 to S7, the magnitudes of Iu, Iv, and Iw are compared, and the rotational position (electrical angle) of the stopped rotor is in any one of the sections A1, A2, B1, B2, C1, and C2. Determine if it is in.

  If it is determined that the rotational position (electrical angle) of the rotor is in section A1 or section A2, the process proceeds to step S11.

In step S11, a pulse voltage of 80% duty is applied as a positive voltage on the U-phase winding side and a negative voltage on the V-phase and W-phase winding sides during 4 control cycles (+ 80% duty pulse voltage is applied). In addition, the U-phase current Iu in the positive direction is measured, and the pulse voltage of 80% duty is set to the positive voltage on the V and W-phase winding sides during four control cycles, and the U-phase winding side is set to the negative voltage. Applied (applied with a pulse voltage of −80% duty) and measured the U-phase current Iu (N) in the negative direction.
When a pulse voltage of 80% duty (for example, 80V × 80% = 64V) is applied for 4 control cycles in this way, the winding is saturated although no overcurrent occurs. In other words, it intentionally causes a saturation phenomenon.

And in step 20,
Iu (N)> Iu (1)
It is determined whether or not.

  If it is determined that the rotational position (electrical angle) θ of the rotor is the section A1, and the expression (1) is satisfied, it is determined that θ is the section A3 advanced by 180 ° from the section A1 ( If the formulas (S21) and (1) are not satisfied, it is determined that θ is the section A1 (S22).

  If it is determined that the rotational position (electrical angle) θ of the rotor is the section A2, and the equation (1) is satisfied, it is determined that θ is the section A4 advanced 180 ° from the section A2 ( If the formulas (S21) and (1) are not satisfied, it is determined that θ is the section A2 (S22).

When it is determined that the rotational position (electrical angle) of the rotor is in the section B1 or the section B2, the process proceeds to step S12.
In step S12, an 80% duty pulse voltage is applied as a positive voltage on the V-phase winding side and a negative voltage on the W and U-phase winding sides during four control cycles (+ 80% duty pulse voltage is applied). ) And measuring the V-phase current Iv in the positive direction, and setting the 80% duty pulse voltage as the positive voltage and the V-phase winding side as the negative voltage during the four control cycles. Applied (applied with a pulse voltage of −80% duty) and measured the V-phase current Iv (N) in the negative direction.
As described above, when the pulse voltage of 80% duty is applied during the four control periods, the magnetic flux is saturated although no overcurrent occurs. In other words, it intentionally causes a saturation phenomenon.

And in step 20,
Iv (N)> Iv (2)
It is determined whether or not.

  If it is determined that the rotational position (electrical angle) θ of the rotor is the section B1, and the expression (2) is satisfied, it is determined that θ is the section B3 advanced by 180 ° from the section B1 ( If the equations (S21) and (2) are not satisfied, it is determined that θ is the section B1 (S22).

  If it is determined that the rotational position (electrical angle) θ of the rotor is in the section B2, and the equation (2) is satisfied, it is determined that the θ is a section B4 advanced by 180 ° from the section B2 ( If the equations (S21) and (2) are not satisfied, it is determined that θ is the section B2 (S22).

When it is determined that the rotational position (electrical angle) of the rotor is the section C1 or the section C2, the process proceeds to step S13.
In step S13, an 80% duty pulse voltage is applied as a positive voltage on the W-phase winding side and a negative voltage on the U and V-phase winding sides during four control periods (+ 80% duty pulse voltage is applied). In addition, the W-phase current Iw in the positive direction is measured, and a pulse voltage of 80% duty is set to a positive voltage on the U and V-phase winding sides and a negative voltage on the W-phase winding side during four control cycles. Applied (applied with a pulse voltage of −80% duty) and measured the V-phase current Iw (N) in the negative direction.
As described above, when the pulse voltage of 80% duty is applied for 4 control periods, the winding is saturated although no overcurrent occurs. In other words, it intentionally causes a saturation phenomenon.

And in step 20,
Iw (N)> Iw (3)
It is determined whether or not.

  If it is determined that the rotational position (electrical angle) θ of the rotor is in the section C1, and the equation (3) is satisfied, it is determined that θ is a section C3 advanced by 180 ° from the section C1 ( If the equations (S21) and (3) are not satisfied, it is determined that θ is the section C1 (S22).

  If it is determined that the rotational position (electrical angle) θ of the rotor is the section C2, and the equation (3) is satisfied, it is determined that θ is the section C4 advanced by 180 ° from the section C2 ( If the equations (S21) and (3) are not satisfied, it is determined that θ is the section C2 (S22).

  Thus, by determining which of the 12 sections of sections A1 to A4, B1 to B4, and C1 to C4 the rotational position (electrical angle) of the rotor is included, the rotational position is set to 30 °. It can be estimated in steps, and can be started by supplying a current having a phase corresponding to the estimated rotational position to an IPM type brushless DC motor.

  In order to detect the rotational position of the rotor in more detail, an arithmetic expression is prepared in advance for each section, and the phase currents Iu, Iv, Iu obtained in each section are substituted into the arithmetic expression. It is also possible to estimate with higher accuracy (for example, the average estimation error is ± 5.2 °) (see Patent Document 2).

JP 2001-136777 A Japanese Patent Laid-Open No. 7-177788

  By the way, based on the characteristics shown in FIG. 8, in the conventional technique for estimating the rotational position by the method shown in FIG. 9, the estimated angle is in increments of 30 °, and the estimation accuracy is rough.

  Further, it is determined which section the rotational position of the rotor enters, and further, an arithmetic expression is prepared for each section, and the phase currents Iu, Iv, Iu obtained in each section are used as the arithmetic expression. In the method for obtaining the rotational position of the rotor by substituting, it is necessary to prepare a large number of complicated arithmetic expressions and to perform advanced calculations. As a result, the calculation load is heavy, and it takes time to detect the rotational position, and an expensive calculation element is required.

  In view of the above-described prior art, the present invention is capable of accurately and easily estimating the rotational position (electrical angle) of a stopped rotor and detecting the initial rotational position of the brushless DC motor and the initial rotational speed. An object is to provide a position detection method.

The configuration of the initial rotational position detection device for a brushless DC motor of the present invention that solves the above problems is as follows.
The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. An initial rotational position detection device for a brushless DC motor, which is used in a magnetless brushless DC motor and detects a rotational position where the rotor is stopped,
A motor power supply for supplying current to the three-phase stator winding;
Current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is magnetically saturated. As described above, the fixed current is supplied from the motor power supply unit so that a current flows from the two windings to the one winding, and the one winding is sequentially changed into a U phase, a V phase, and a W phase. A pulse voltage drive controller for controlling the pulse voltage to be supplied to the child winding;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. When the U-phase current, V-phase current, W-phase current, and the one winding are changed in sequence to the U-phase, V-phase, and W-phase, current is supplied from the two windings to the one winding. A current detector for detecting negative U-phase current, V-phase current, and W-phase current flowing in the one winding when the current flows;
A calculation / determination control unit that estimates the rotational position where the rotor is stopped based on the positive and negative U-phase current, V-phase current, and W-phase current detected by the current detector; ,
The arithmetic / judgment control unit
By determining which of the positive U phase current, V phase current, and W phase current detected by the current detector is the largest, the rotational position where the rotor is stopped is It is determined that the corner is one of the first to third sections obtained by dividing the corner into three sections,
Furthermore, when the largest positive phase current is smaller than the negative phase current of the same phase, the rotational position at which the rotor is stopped is the angle of the boundary between two sections different from the determined section And determine
Furthermore, in the determined section, when the largest positive phase current is larger than the negative phase current of the same phase, the difference between the largest phase current and the second largest phase current and the second largest phase current The rotational position at which the rotor is stopped is determined by referring to data in which the deviation and the rotational position are allocated in advance according to the difference between the difference between the rotational current and the smallest phase current.

in this case,
The current values of the U-phase current, V-phase current, and W-phase current in the positive and negative directions are 1.3 to 1.6 times the rated current of the brushless DC motor,
The deviation is 4 times or less, 4 times or more, 32 times or more deviation,
The deviation is a deviation of 2 times or less, 2 times or more, 4 times or more, 8 times or more, 32 times or more.

The configuration of the method for detecting the initial rotational position of the brushless DC motor of the present invention is as follows:
The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. A method for detecting an initial rotational position of a brushless DC motor, which is used in a magnet-less brushless DC motor and detects a rotational position where the rotor is stopped,
Current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is magnetically saturated. As described above, a current is passed from the two windings to the one winding, and a pulse is applied to the stator winding so that the one winding is changed in order of U phase, V phase, and W phase. Supply voltage,
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. When the U-phase current, V-phase current, W-phase current, and the one winding are changed in sequence to the U-phase, V-phase, and W-phase, current is supplied from the two windings to the one winding. Detecting negative U-phase current, V-phase current, and W-phase current flowing in the one winding when flowing,
By determining which of the detected positive U-phase current, V-phase current, and W-phase current is the largest, the rotational position at which the rotor is stopped is divided into three electrical angles of 360 °. Is determined to be one of the first to third sections,
Further, when the largest positive phase current is smaller than the negative phase current of the same phase, the rotational position at which the rotor is stopped is the angle of the boundary between two sections different from the determined section And determine
Furthermore, in the determined section, when the largest positive phase current is larger than the negative phase current of the same phase, the difference between the largest phase current and the second largest phase current and the second largest phase current The rotational position at which the rotor is stopped is determined by referring to data in which the deviation and the rotational position are allocated in advance according to the difference between the difference between the rotational current and the smallest phase current.

in this case,
The current values of the U-phase current, V-phase current, and W-phase current in the positive and negative directions are 1.3 to 1.6 times the rated current of the brushless DC motor,
The deviation is 4 times or less, 4 times or more, 32 times or more deviation,
The deviation is a deviation of 2 times or less, 2 times or more, 4 times or more, 8 times or more, 32 times or more.

In addition, the configuration of the initial rotational position detection device of the brushless DC motor of the present invention is as follows:
The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. An initial rotational position detection device for a brushless DC motor, which is used in a magnetless brushless DC motor and detects a rotational position where the rotor is stopped,
A motor power supply for supplying current to the three-phase stator winding;
A current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is connected to U A pulse voltage drive control unit that performs control to supply a pulse voltage from the motor power supply unit to the stator winding so as to sequentially change the phase, the V phase, and the W phase;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. A current detector for detecting a U-phase current, a V-phase current, and a W-phase current,
A calculation / determination control unit that estimates the rotational position where the rotor is stopped based on the positive U phase current, V phase current, and W phase current detected by the current detector;
The arithmetic / judgment control unit
By determining which of the positive U phase current, V phase current, and W phase current detected by the current detector is the largest, the rotational position where the rotor is stopped is It is determined that the corner is one of the first to third sections obtained by dividing the corner into three sections,
Further, in the determined section, the value of this ratio is determined according to the value of the ratio between the difference between the largest phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current. The rotational position at which the rotor is stopped is determined by referring to the data in which the rotor and the rotational position are allocated in advance.

The configuration of the method for detecting the initial rotational position of the brushless DC motor of the present invention is as follows:
The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. A method for detecting an initial rotational position of a brushless DC motor, which is used in a magnet-less brushless DC motor and detects a rotational position where the rotor is stopped,
A current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is connected to U Supplying a pulse voltage to the stator winding so as to change in order of phase, V phase, and W phase;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. Detect U phase current, V phase current, W phase current,
By determining which of the detected positive U-phase current, V-phase current, and W-phase current is the largest, the rotational position at which the rotor is stopped is divided into three electrical angles of 360 °. Is determined to be one of the first to third sections,
Further, in the determined section, the value of this ratio is determined according to the value of the ratio between the difference between the largest phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current. The rotational position at which the rotor is stopped is determined by referring to the data in which the rotor and the rotational position are allocated in advance.

The configuration of the method for detecting the initial rotational position of the brushless DC motor of the present invention is as follows:
The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. A method for detecting an initial rotational position of a brushless DC motor, which is used in a magnet-less brushless DC motor and detects a rotational position where the rotor is stopped,
Current is passed from the one winding to the remaining two windings so that one winding of the three-phase stator windings is not magnetically saturated. Supplying a pulse voltage to the stator winding so as to change in order of phase, V phase, and W phase;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. Detect U phase current, V phase current, W phase current,
By determining which one of the detected positive U-phase current, V-phase current, and W-phase current is the largest, the rotational position at which the rotor is stopped has an electrical angle of 60 in each section. It is determined that it is one of three sections that are 60 ° apart from each other at an electrical angle of 60 °,
In each section, the value of the difference between the largest phase current and the second largest phase current is divided into a case where the difference is larger and smaller than a predetermined minute value, and the rotor stops in each section. Is determined to be a pre-set angle for each divided state,
Next, current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding Current is passed from the two windings to the one winding so as to be magnetically saturated, and the one winding is changed in order of U phase, V phase, and W phase. Supply pulse voltage to the wire,
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. When the U-phase current, V-phase current, W-phase current, and the one winding are changed in sequence to the U-phase, V-phase, and W-phase, current is supplied from the two windings to the one winding. Detecting negative U-phase current, V-phase current, and W-phase current flowing in the one winding when flowing,
In each section, when the positive phase current is larger than the negative phase current, it is determined that the rotor is stopped at the determined angle, and the negative phase current is the positive phase current. When the current is smaller than the current, it is determined that the position where the rotor is stopped is an angle advanced by 180 ° from the determined angle.

  According to the present invention, a U-phase current, a V-phase current, and a W-phase current obtained by passing a current that causes the winding to be magnetically saturated is detected, and the difference between the largest phase current and the second largest phase current is detected. Based on the "deviation" and "ratio value" between the difference between the second largest phase current and the smallest phase current, the rotational position of the rotor of the embedded magnet type brushless DC motor (stopped) Therefore, the rotational position of the stopped rotor can be detected easily and accurately.

  In addition, since a current that is magnetically saturated flows, the value of the largest phase current of the three-phase currents differs greatly from the values of the other two phase currents. It was possible to improve.

  In the embodiment of the present invention, the initial rotational position estimation current characteristic in the IPM type brushless DC motor shown in FIG. 1 is used. The initial rotational position estimation current characteristic shown in FIG. 1 is obtained by the inventor's earnest research. The horizontal axis indicates the rotational position (electrical angle) of the rotor, and the vertical axis indicates the U-phase currents Iu and V. The phase current Iv and the W phase current Iw are shown.

Next, a method for obtaining the initial rotational position estimation current characteristic shown in FIG. 1 will be described.
In this method, the current characteristic is obtained by passing a current of the degree that “magnetic saturation occurs”, which is a special technical feature for the present invention.

(1) A method for obtaining the characteristics of the U-phase current Iu.
When the rotor of the IPM type brushless DC motor is stopped at each electrical angle, between the external terminal of the U-phase winding and the terminal sharing the external terminals of the V-phase winding and the W-phase winding In addition, a pulse voltage is applied with the U-phase winding side set as a positive voltage and the V-phase winding and the W-phase winding side set as a negative voltage, and a current (for example, a motor rating) that causes “magnetic saturation” in the U-phase winding. A current of about 1.3 to 1.6 times the current). Thus, the current characteristic of the U-phase current Iu is obtained by plotting the U-phase current Iu for each electrical angle.

(2) A method for obtaining the characteristics of the V-phase current Iv.
When the rotor of the IPM type brushless DC motor is stopped at each electrical angle, between the external terminal of the V-phase winding and the terminal sharing the external terminal of the W-phase winding and U-phase winding In addition, a pulse voltage is applied with a positive voltage on the V-phase winding side and a negative voltage on the W-phase winding and the U-phase winding side, and a current (for example, a motor rating) that causes “magnetic saturation” in the V-phase winding. A current of about 1.3 to 1.6 times the current). In this way, the current characteristic of the V-phase current Iv is obtained by plotting the V-phase current Iv for each electrical angle.

(3) A method for obtaining the characteristics of the W-phase current Iw.
When the rotor of the IPM type brushless DC motor is stopped at each electrical angle, between the external terminal of the W-phase winding and the terminal sharing the external terminal of the U-phase winding and the V-phase winding In addition, a pulse voltage is applied with the W-phase winding side set as a positive voltage and the U-phase winding and V-phase winding side set as a negative voltage. A current of about 1.3 to 1.6 times the current). Thus, the current characteristic of the W-phase current Iw is obtained by plotting the W-phase current Iw for each electrical angle.

When determining the rotational position described later,
Apply a pulse voltage with a negative voltage on the U-phase winding side and a positive voltage on the V-phase winding and W-phase winding sides. Negative current U-phase current Iu (N) when a current of about 1.3 to 1.6 times is applied,
Apply a pulse voltage with a negative voltage on the V-phase winding side and a positive voltage on the W-phase winding and U-phase winding sides. V-phase current Iv (N) in the negative direction when a current of about 1.3 to 1.6 times is passed,
Apply a pulse voltage with a negative voltage on the W-phase winding side and a positive voltage on the U-phase winding and V-phase winding sides, and a current that is “magnetic saturation occurs” in the W-phase winding (for example, motor rated current The W-phase current Iw (N) in the negative direction when a current having a value of about 1.3 to 1.6 times is also detected.

The initial rotational position estimation current characteristic shown in FIG. 1 has the following characteristics.
Note that “substantially” means that the characteristics of the sections I to III described below are shifted in the vicinity of 30 °, 270 °, and 150 °.

In the section I (from 30 ° to 150 °), the phase current Iu is larger than the phase currents Iv and Iw.
When this section I is further divided into two sections I-1 (30 ° to 90 °) and section I-2 (90 ° to 150 °),
In section I-1, Iu>Iv> Iw,
In the section I-2, Iu>Iw> Iv.

In the section II (270 ° to 30 ° (390 °)), the phase current Iw is larger than the phase currents Iu and Iv.
When this section II is further divided into two sections II-1 (270 ° to 330 °) and section II-2 (330 ° to 30 ° (390 °),
In section II-1, Iw>Iu> Iv,
In section II-2, Iw>Iv> Iu.

Section III (in the range of 150 ° to 270 °, the phase current Iv is larger than the phase currents Iw and Iu.
When this section III is further divided into two sections III-1 (150 ° to 210 °) and section III-2 (210 ° to 270 °),
In section III-1, Iv>Iw> Iu,
In the section III-2, Iv>Iu> Iw.

In addition,
In the vicinity of 30 ° (including the boundary between section I and section II, near this boundary), Iv is the largest, and in the vicinity of 270 ° (including the boundary between section II and section III, near this boundary), Iu is the largest. In the vicinity of 150 ° (including the boundary between section III and section I and in the vicinity of this boundary), Iw is the largest.

In the present embodiment, when the rotor of the IPM motor is stopped, each phase current Iu, Iv, Iw in the positive direction and each phase current Iu (N), Iv (N), Iw (N )
Then, by determining which of the phase currents Iu, Iv, and Iw is the largest, the sections I to III are determined. Further, in the determined section, among the phase currents Iu, Iv, and Iw, Based on the difference between the difference between the large phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current, the rotational position of the rotor is determined. Judgment.

The deviation is 4 times or less, 4 times or more, 32 times or more, 2 times or less, 2 times or more, 4 times or more, 8 times or more, 32 times or more.
When the rated current is 1.3 times the rated current, the phase current to be flowed can be 20 times instead of 32 times as the deviation.

  In another embodiment of the present invention, the initial rotational position / phase current relationship characteristic α in the IPM type brushless DC motor shown in FIG. 2 is used.

This characteristic α is first obtained the initial rotational position estimated current characteristic shown in FIG. 1, and based on this initial rotational position estimated current characteristic,
In section I, α = (Iu−Iv) / (Iv−Iw)
In section II, α = (Iw−Iu) / (Iu−Iv)
In section III, α = (Iv−Iw) / (Iw−Iu)
Asking.
That is, in each of the sections I, II, and III, among the phase currents Iu, Iv, and Iw, “the difference between the largest phase current and the second largest phase current” and “the second largest phase current and the smallest phase current”. The ratio with the “difference with current” is defined as a characteristic α.

In this other embodiment, the respective phase currents Iu, Iv, Iw in the positive direction are obtained when the rotor of the IPM motor is stopped.
Then, by determining which of the phase currents Iu, Iv, and Iw is the largest, the sections I to III are determined. Further, in the determined section, among the phase currents Iu, Iv, and Iw, The rotation angle at which the value of the ratio between the difference between the large phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current matches the value of the characteristic α is It is determined as the rotational position of the rotor.

  FIG. 3 is a block diagram illustrating an initial rotational position detection device for a brushless DC motor according to the first embodiment of the present invention.

  As shown in FIG. 3, the inverter device 100 supplies the power of the battery 101 to the IPM type brushless DC motor 110. The stator of the brushless DC motor 110 includes a three-phase U-phase stator winding 111u, a V-phase stator winding 111v, and a W-phase stator winding 111w. A rotor 112 is arranged inside the stator via an air gap, and a plurality of permanent magnets 113 are embedded in the rotor 112.

When starting the rotor 112, the inverter device (motor power supply unit) 100 receives the rotation position signal S1 from the initial rotation position detection unit 120, as will be described later, and receives the rotation position (stopped) indicated by the rotation position signal S1. The brushless DC motor 110 is started by supplying a three-phase current having a phase corresponding to the electrical angle of the rotor 112 that is present.
Further, the inverter device 100 supplies a three-phase current to the brushless DC motor 110 when the rotor 112 is normally rotated (continuous rotation after starting).
Further, when the inverter device 100 detects the rotational position (electrical angle) of the rotor 112 that is stopped prior to the start of the rotor 112, a pulse voltage drive signal is output from the initial rotational position detector 120 as described later. In response to S2, a pulse voltage is applied to the brushless DC motor 110.

  The initial rotation position detection unit 120 includes a pulse voltage drive control unit 121, a calculation / determination unit 122, and a memory 123.

The current detector 131 detects the positive U-phase current Iu or the negative U-phase current Iu (N).
The current detector 132 detects a positive V-phase current Iv or a negative V-phase current Iv (N).
The current detector 133 detects a positive W-phase current Iw or a negative W-phase current Iw (N).

  The phase currents Iu, Iu (N), Iv, Iv (N), Iw, and Iw (N) detected by the current detectors 131, 132, and 133 are calculated and determined by the initial rotation position detection unit 120. Sent to.

  In the first embodiment, the initial rotational position estimation current characteristic shown in FIG. 1 is stored in the memory 123 of the initial rotational position detection unit 120.

  In the first embodiment, the following operation is performed to obtain the rotational position (stopped electrical angle) of the stopped rotor 112.

  The pulse voltage drive control unit 121 of the initial rotational position detection unit 120 sends a pulse voltage drive signal S2 to the inverter device 110, applies a pulse voltage from the inverter device 100 to the brushless DC motor 110, and the stator windings 111u, 111v, A current is passed through 111w.

In particular,
A pulse voltage is applied with the U-phase winding 111u side as a positive voltage and the V-phase winding 111v and the W-phase winding 111w side as a negative positive voltage. For example, a U-phase current Iu in the positive direction when a current having a value about 1.3 to 1.6 times the motor rated current)
A pulse voltage is applied with a negative voltage on the U-phase winding 111u side and a positive voltage on the V-phase winding 111v and W-phase winding 111w sides, and a current (for example, magnetic saturation occurs) in the U-phase winding 111u (for example, Negative current U-phase current Iu (N) when a current of about 1.3 to 1.6 times the motor rated current is applied,
A pulse voltage is applied with the V-phase winding 111v side set as a positive voltage and the W-phase winding 111w and U-phase winding 111u sides set as negative voltages, and a current (for example, magnetic saturation occurs) in the V-phase winding 111v (for example, Motor V current Vv in the positive direction when a current of about 1.3 to 1.6 times the motor rated current)
A pulse voltage is applied with a negative voltage on the V-phase winding 111v side and a positive voltage on the W-phase winding 111w and U-phase winding 111u sides, and a current (for example, magnetic saturation occurs) in the V-phase winding 111v (for example, Negative phase V-phase current Iv (N) when a current of about 1.3 to 1.6 times the motor rated current is passed,
A pulse voltage is applied with the W-phase winding 111w side as a positive voltage and the U-phase winding 111u and the V-phase winding 111v side as negative voltages, and a current (for example, magnetic saturation occurs) in the W-phase winding 111w (for example, W-phase current Iw in the positive direction when a current of about 1.3 to 1.6 times the motor rated current is passed,
A pulse voltage is applied with a negative voltage on the W-phase winding 111w side and a positive voltage on the U-phase winding 111u and V-phase winding 111v sides, and a current (for example, magnetic saturation occurs) in the W-phase winding 111w (for example, The W-phase current Iw (N) in the negative direction when a current having a value of about 1.3 to 1.6 times the motor rated current is passed.

The current detection unit 131 detects the positive U-phase current Iu and the negative U-phase current Iu (N), and sends the detected U-phase current Iu and U-phase current Iu (N) to the calculation / determination unit 122. .
The current detector 132 detects the positive V-phase current Iv and the negative V-phase current Iv (N), and sends the detected V-phase current Iv and V-phase current Iv (N) to the calculation / determination unit 122. .
The current detection unit 133 detects the W-phase current Iw in the positive direction and the W-phase current Iw (N) in the negative direction, and sends the detected W-phase current Iw and W-phase current Iw (N) to the calculation / determination unit 122. .

  The calculation / determination unit 122 shows each phase current detected by the current detection units 131, 132, and 133 with reference to the initial rotational position estimated current characteristic (characteristic shown in FIG. 1) stored in the memory 123 as shown in FIG. A determination is made along the determination flowchart to determine the rotational position (electrical angle) of the stopped rotor 112.

Here, the rotational position detection method according to the determination flowchart shown in FIG. 4 will be described.
In step S100, it is compared which of the phase currents Iu, Iv, and Iw is greater.

  When it is determined in step S100 that the U-phase current Iu is large, in step S110, the positive U-phase current Iu is compared with the negative U-phase current Iu (N), and the negative U-phase current Iu is compared. When the current Iu (N) is large, it is determined that the rotation angle is 280 ° to 260 °.

  If it is determined in step S110 that Iu> Iu (N), the V-phase current Iv and the W-phase current Iw are compared in step S111.

When it is determined in step S111 that the V-phase current Iv is larger than the W-phase current Iw, it is determined that the rotational position is in the section I-1, and determinations in steps S112 and S113 are performed.
When | Iu−Iv |> | Iv−Iw | × 32, it is determined that the rotational position is 100 ° to 80 °,
When | Iu−Iv |> | Iv−Iw | × 4, it is determined that the rotational position is 80 ° to 60 °,
When | Iu−Iv | ≦ | Iv−Iw | × 4, it is determined that the rotational position is 60 ° to 40 °.

When it is determined in step S111 that the V-phase current Iv is smaller than the W-phase current Iw, it is determined that the rotational position is in the section I-2, and the determinations in steps S114 and S115 are performed.
When | Iu−Iw |> | Iw−Iv | × 32, it is determined that the rotational position is 100 ° to 80 °,
When | Iu−Iw |> | Iw−Iv | × 4, it is determined that the rotational position is 120 ° to 100 °,
When | Iu−Iw | ≦ | Iw−Iv | × 4, it is determined that the rotational position is 140 ° to 120 °.

  When it is determined in step S100 that the W-phase current Iw is large, in step S120, the positive-direction W-phase current Iw is compared with the negative-direction W-phase current Iw (N), and the negative-direction W-phase is compared. When the current Iw (N) is large, it is determined that the rotation angle is 160 ° to 140 °.

  When it is determined in step S120 that Iw> Iw (N), the V-phase current Iv and the U-phase current Iu are compared in step S121.

When it is determined in step S121 that the V-phase current Iv is larger than the U-phase current Iu, it is determined that the rotational position is in the section II-2, and the determinations in steps S122 and S123 are performed.
When it is | Iw−Iv |> | Iv−Iu | × 32, it is determined that the rotational position is 340 ° to 320 °,
When | Iw−Iv |> | Iv−Iu | × 4, it is determined that the rotational position is 360 ° to 340 °,
When | Iw−Iv | ≦ | Iv−Iu | × 4, it is determined that the rotational position is 20 ° to 0 °.

When it is determined in step S121 that the V-phase current Iv is smaller than the U-phase current Iu, it is determined that the rotational position is in the section II-1, and the determinations in steps S124 and S125 are performed.
When | Iw−Iu |> | Iu−Iv | × 32, it is determined that the rotational position is 340 ° to 320 °,
When | Iw−Iu |> | Iu−Iv | × 4, it is determined that the rotational position is 320 ° to 300 °,
When | Iw−Iu | ≦ | Iu−Iv | × 4, it is determined that the rotational position is 300 ° to 280 °.

  When it is determined in step S100 that the V-phase current Iv is large, in step S130, the positive-direction V-phase current Iv is compared with the negative-direction V-phase current Iv (N), and the negative-direction V-phase current Iv is compared. When the current Iv (N) is large, it is determined that the rotation angle is 40 ° to 20 °.

  If it is determined in step S130 that Iv> Iv (N), the U-phase current Iu and the W-phase current Iw are compared in step S131.

When it is determined in step S131 that the U-phase current Iu is larger than the W-phase current Iw, it is determined that the rotational position is in the section III-2, and determinations in steps S132 and S133 are performed.
When | Iv−Iu |> | Iu−Iw | × 32, it is determined that the rotational position is 220 ° to 200 °,
When | Iv−Iu |> | Iu−Iw | × 4, it is determined that the rotational position is 240 ° to 220 °,
When | Iv−Iu | ≦ | Iu−Iw | × 4, it is determined that the rotational position is 260 ° to 240 °.

When it is determined in step S131 that the U-phase current Iu is smaller than the W-phase current Iw, it is determined that the rotational position is in the section III-1, and the determinations in steps S134 and S135 are performed.
When | Iv−Iw |> | Iw−Iu | × 32, it is determined that the rotational position is 220 ° to 200 °,
When | Iv−Iw |> | Iw−Iu | × 4, it is determined that the rotational position is 200 ° to 180 °,
When | Iv−Iw | ≦ | Iw−Iu | × 4, it is determined that the rotational position is 180 ° to 160 °.

In this way, the calculation / determination unit 122 can determine the rotational position of the stopped rotor 112 in increments of 20 °.
When the rotational position signal S1 indicating the rotational position determined in increments of 20 ° is sent to the inverter device 100, the inverter device 100 has a three-phase current having a phase corresponding to the rotational position indicated by the rotational position signal S1. Can be supplied to the brushless DC motor 110 to start.

In the first embodiment, the calculation / determination unit 122 of the initial rotational position detection unit 120 obtains the rotational position of the stopped rotor 112 according to the determination flowchart shown in FIG. The rotational position of the stopped rotor 112 is determined in increments of 10 ° according to the determination flowchart shown in FIG.
The configuration and operation of other parts in the second embodiment are the same as those in the first embodiment.

  In the second embodiment, the sections I to III are determined by determining which of the phase currents Iu, Iv, and Iw is the largest (same as in the first embodiment). Further, in the second embodiment, the determination is performed. Of the phase currents Iu, Iv, and Iw, the difference between the largest phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current. The rotational position of the rotor is determined by determining whether the deviation is 32 times, 8 times, 4 times, or 2 times.

Specifically, in Step S200, sections I to III are determined by determining which of the phase currents Iu, Iv, and Iw is the largest.
Next, in section I, the determination of steps S211 to S219 determines which range in 10 ° increments in section I the rotational position falls into,
Next, in section III, it is determined by the determination in steps S221 to S229 which range the rotation position falls in 10 ° increments in section I.
Next, in section II, it is determined in step S231 to S239 which range the rotational position falls in 10 ° increments in section I.

The third embodiment is realized by the brushless DC motor initial rotational position detection device shown in FIG. 3, but the initial rotational position / phase current relationship characteristics shown in FIG. 2 are stored in the memory 123 of the initial rotational position detector 120. α is stored.
Then, the calculation / determination unit 122 of the initial rotation position detection unit 120 performs calculation / determination to be described later, and accurately determines the rotation position of the stopped rotor 112 in increments (for example, 1 ° to 0.5 °). Can be determined.

Further, the pulse voltage drive control device 121 controls the inverter device 100 so that the positive U-phase current Iu, the positive V-phase current Iv, and the positive W-phase current Iw flow. This is because the negative direction U-phase current Iu (N), V-phase current Iv (N), and W-phase current Iw (N) are not used in the third embodiment.
The other partial configurations and operations in the third embodiment are the same as those in the first embodiment.

  In the third embodiment, the U-phase currents Iu, Iv, and Iw in the positive direction obtained by applying the pulse voltage from the inverter device 100 when the rotor 112 is stopped are taken into the calculation / determination unit 122. .

  The calculation / determination unit 122 compares the U-phase current Iu, the phase current Iv, and the W-phase current Iw to determine the largest phase current.

When it is determined that the U-phase current Iu is the largest, the calculated value β (I) obtained by the following equation (1) is calculated.
β (I) = (Iu−Iv) / (Iv−Iw) (1)
The calculated value β (I) calculated in this way is compared with the characteristic α in the section I stored in the memory 123, and the rotational position (electrical angle) where β (I) = α is obtained. It is determined that the rotation angle obtained in this way is the rotation position (electrical angle) of the rotor 112 that is stopped.

When it is determined that the V-phase current Iv is the largest, the calculated value β (II) obtained by the following equation (2) is calculated.
β (II) = (Iw−Iu) / (Iu−Iv) (2)
The calculated value β (II) calculated in this way is compared with the characteristic α in the section II stored in the memory 123 to obtain a rotational position (electrical angle) where β (II) = α. It is determined that the rotation angle obtained in this way is the rotation position (electrical angle) of the rotor 112 that is stopped.

When it is determined that the W-phase current Iw is the largest, the calculated value β (III) obtained by the following equation (3) is calculated.
β (III) = (Iv−Iw) / (Iw−Iu) (3)
The calculated value β (III) calculated in this way is compared with the characteristic α in the section III stored in the memory 123, and the rotational position (electrical angle) where β (III) = α is obtained. It is determined that the rotation angle obtained in this way is the rotation position (electrical angle) of the rotor 112 that is stopped.

The fourth embodiment is realized by the initial rotational position detection device for the brushless DC motor shown in FIG. 3, but the initial rotational position estimation shown in FIG. Current is stored.
Then, the calculation / determination unit 122 of the initial rotation position detection unit 120 can perform calculation / determination described later, and can determine the rotation position of the stopped rotor 112 more accurately than in the past.
In other words, the fourth embodiment is a further improvement of the conventional determination method shown in the determination flowchart shown in FIG. In the fourth embodiment, the rotational position of the stopped rotor 112 can be determined in 15 ° increments by improving the determination method. Incidentally, in the conventional determination method shown in FIG. 9, the rotational position of the rotor 112 is determined in increments of 30 °.

A specific method of determination in Example 4 is shown in FIG.
First, in step 1 (S300), a pulse voltage of + 100% duty is applied for three control periods, and each phase current Iu, Iv, Iw is measured. Each phase current flowing at this time becomes a current having a value equal to or less than the rated current without saturating the winding.

Here, “one control cycle” is a control cycle for controlling the current value of the current supplied from the inverter device to the motor, and for example, one control cycle is 125 μsec.
Also, “+ 100% duty”
For U-phase current, the U-phase winding side is set to a positive voltage, the V and W-phase winding sides are set to a negative voltage (meaning “+”),
For V-phase current, the V-phase winding side is set to a positive voltage, the W and U-phase winding sides are set to a negative voltage (meaning “+”),
If it is a W-phase current, the W-phase winding side is a positive voltage, the U and V-phase winding sides are a negative voltage (meaning “+”),
Applying a voltage (for example, 80V) having a duty of 100% of the voltage value (for example, 80V) of the power supply voltage (meaning “100% duty”).

  In steps S301 to S306, the magnitudes of Iu, Iv, and Iw are compared, and the rotational position (electrical angle) of the stopped rotor is in any one of the sections A1, A2, B1, B2, C1, and C2. Determine if it is in.

  When it is determined that the rotational position (electrical angle) of the rotor is in section A1, that is, when it is determined YES in step S301, the process proceeds to step S310.

In step S310, it is determined whether or not the difference (absolute value) between the U-phase current Iu and the V-phase current Iv is larger than a preset minute current value ΔI (specifically, 1/10 of the rated current). Determined.
When it is determined that the difference (absolute value) between the U-phase current Iu and the V-phase current Iv is smaller than the preset minute current value ΔI, it is determined that θ = 60 ° (step S311). When it is determined that the difference (absolute value) between the phase current Iu and the V-phase current Iv is greater than the preset minute current value ΔI, θ = 75 ° is determined (step S312).

  When it is determined that the rotational position (electrical angle) of the rotor is in the section A2, that is, when it is determined YES in step S302, the process proceeds to step S320.

In step S320, whether or not the difference (absolute value) between the U-phase current Iu and the W-phase current Iw is larger than a preset minute current value ΔI (specifically, 1/10 of the rated current). Determined.
When it is determined that the difference (absolute value) between the U-phase current Iu and the W-phase current Iw is smaller than a preset minute current value ΔI, it is determined that θ = 120 ° (step S321). When it is determined that the difference (absolute value) between the phase current Iu and the W-phase current Iw is larger than the preset minute current value ΔI, θ = 105 ° is determined (step S322).

  When it is determined that the rotational position (electrical angle) of the rotor is in the section C1, that is, when it is determined YES in step S303, the process proceeds to step S330.

In step S330, it is determined whether or not the difference (absolute value) between the W-phase current Iw and the U-phase current Iu is greater than a preset minute current value ΔI (specifically, 1/10 of the rated current). Determined.
When it is determined that the difference (absolute value) between the W-phase current Iw and the U-phase current Iu is smaller than a preset minute current value ΔI, θ is determined to be 300 ° (step S331). When it is determined that the difference (absolute value) between the phase current Iw and the U-phase current Iu is larger than the preset minute current value ΔI, θ = 315 ° is determined (step S332).

  When it is determined that the rotational position (electrical angle) of the rotor is in the section C2, that is, when YES is determined in step S304, the process proceeds to step S340.

In step S340, whether or not the difference (absolute value) between the W-phase current Iw and the V-phase current Iv is larger than a preset minute current value ΔI (specifically, 1/10 of the rated current). Determined.
When it is determined that the difference (absolute value) between the W-phase current Iw and the V-phase current Iv is smaller than the preset minute current value ΔI, it is determined that θ = 360 ° (step S341). When it is determined that the difference (absolute value) between the phase current Iw and the V-phase current Iv is larger than the preset minute current value ΔI, θ = 345 ° is determined (step S342).

  When it is determined that the rotational position (electrical angle) of the rotor is in the section B1, that is, when YES is determined in step S305, the process proceeds to step S350.

In step S350, whether or not the difference (absolute value) between the V-phase current Iv and the W-phase current Iw is greater than a preset minute current value ΔI (specifically, 1/10 of the rated current). Determined.
When it is determined that the difference (absolute value) between the V-phase current Iv and the W-phase current Iw is smaller than a preset minute current value ΔI, θ is determined to be 180 ° (step S351). When it is determined that the difference (absolute value) between the phase current Iv and the W-phase current Iw is larger than the preset minute current value ΔI, it is determined that θ = 195 ° (step S352).

  When it is determined that the rotational position (electrical angle) of the rotor is in the section B2, that is, when it is determined YES in step S306, the process proceeds to step S360.

In step S360, whether or not the difference (absolute value) between the V-phase current Iv and the U-phase current Iu is larger than a preset minute current value ΔI (specifically, 1/10 of the rated current). Determined.
When it is determined that the difference (absolute value) between the V-phase current Iv and the U-phase current Iu is smaller than a preset minute current value ΔI, it is determined that θ = 240 ° (step S361). When it is determined that the difference (absolute value) between the phase current Iv and the U-phase current Iu is larger than the preset minute current value ΔI, θ = 225 ° is determined (step S362).

  When it is determined in steps S311, S312, S321, and S322 that θ is 60 °, 75 °, 120 °, and 105 °, the process proceeds to step S370.

In step S370, a pulse voltage of 80% duty is applied as a positive voltage on the U-phase winding side and a negative voltage on the V-phase and W-phase winding sides for four control cycles (+ 80% duty pulse voltage is applied). In addition, the U-phase current Iu in the positive direction is measured, and the pulse voltage of 80% duty is set to the positive voltage on the V and W-phase winding sides during four control cycles, and the U-phase winding side is set to the negative voltage. Applied (applied with a pulse voltage of −80% duty) and measured the U-phase current Iu (N) in the negative direction.
When a pulse voltage of 80% duty (for example, 80V × 80% = 64V) is applied for 4 control cycles in this way, the winding is saturated although no overcurrent occurs. In other words, it intentionally causes a saturation phenomenon.

In step S380,
Iu (N)> Iu (11)
It is determined whether or not.

If equation (11) does not hold, θ is determined to be 60 °, 75 °, 120 °, and 105 ° determined in steps S311, S312, S321, and S322 (S380).
On the other hand, if the expression (11) is satisfied, it is determined that θ is an angle advanced by 180 ° from the angle described above (S381).

  When it is determined in steps S331, S332, S341, and S342 that θ is 300 °, 315 °, 360 °, and 345 °, the process proceeds to step S371.

In step S371, a pulse voltage of 80% duty is applied as a positive voltage on the W phase winding side and a negative voltage on the U phase and V phase winding sides during four control cycles (+ 80% duty pulse voltage is applied). In addition, the W-phase current Iw in the positive direction is measured, and a pulse voltage of 80% duty is set to a positive voltage on the U and V-phase winding sides and a negative voltage on the W-phase winding side during four control cycles. Applied (applied with a pulse voltage of −80% duty) and measured W-phase current Iw (N) in the negative direction.
When a pulse voltage of 80% duty (for example, 80V × 80% = 64V) is applied for 4 control cycles in this way, the winding is saturated although no overcurrent occurs. In other words, it intentionally causes a saturation phenomenon.

In step S380,
Iw (N)> Iw (12)
It is determined whether or not.

If equation (12) does not hold, θ is determined to be 300 °, 315 °, 360 °, 345 ° determined in steps S331, S332, S341, and S342 (S380).
On the other hand, when the equation (12) is established, it is determined that θ is an angle advanced by 180 ° from the above-described angle (S381).

  When θ is determined to be 180 °, 195 °, 240 °, or 225 ° in steps S351, S352, S361, and S362, the process proceeds to step S372.

In step S372, an 80% duty pulse voltage is applied as a positive voltage on the V-phase winding side and a negative voltage on the W and U-phase winding sides during four control periods (+ 80% duty pulse voltage is applied). In addition, the V-phase current Iv in the positive direction is measured, and a pulse voltage of 80% duty is applied as a positive voltage on the W-phase winding side and a negative voltage on the V-phase winding side for four control cycles. Then, a negative-direction V-phase current Iv (N) is measured by applying a pulse voltage of −80% duty.
When a pulse voltage of 80% duty (for example, 80V × 80% = 64V) is applied for 4 control cycles in this way, the winding is saturated although no overcurrent occurs. In other words, it intentionally causes a saturation phenomenon.

In step S380,
Iv (N)> Iv (13)
It is determined whether or not.

If equation (13) does not hold, θ is determined to be 180 °, 195 °, 240 °, and 225 ° determined in steps S351, S352, S361, and S362 (S380).
On the other hand, if the equation (13) is established, it is determined that θ is an angle advanced by 180 ° from the above-described angle (S381).

The characteristic view which shows the initial stage rotational position estimation electric current characteristic used by this invention. The characteristic view which shows the initial stage rotation position and phase current relationship characteristic used by this invention. The block diagram which shows the initial stage rotational position detection apparatus of the brushless DC motor based on the Example of this invention. The flowchart which shows the determination flow used in the Example of this invention. The flowchart which shows the determination flow used in another Example of this invention. The flowchart which shows the determination flow used in another Example of this invention. The schematic block diagram which shows an embedded magnet type brushless DC motor. The characteristic view which shows the initial stage rotational position estimation electric current characteristic used with the prior art. The flowchart which shows the determination flow used by the prior art.

Explanation of symbols

100 Inverter device (motor power supply)
DESCRIPTION OF SYMBOLS 101 Battery 110 Brushless DC motor 111u, 111v, 111w Winding 120 Initial position rotation position detection part 121 Pulse voltage drive control part 122 Calculation / determination part 123 Memory

Claims (11)

The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. An initial rotational position detection device for a brushless DC motor, which is used in a magnetless brushless DC motor and detects a rotational position where the rotor is stopped,
A motor power supply for supplying current to the three-phase stator winding;
Current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is magnetically saturated. As described above, the fixed current is supplied from the motor power supply unit so that a current flows from the two windings to the one winding, and the one winding is sequentially changed into a U phase, a V phase, and a W phase. A pulse voltage drive controller for controlling the pulse voltage to be supplied to the child winding;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. When the U-phase current, V-phase current, W-phase current, and the one winding are changed in sequence to the U-phase, V-phase, and W-phase, current is supplied from the two windings to the one winding. A current detector for detecting negative U-phase current, V-phase current, and W-phase current flowing in the one winding when the current flows;
A calculation / determination control unit that estimates the rotational position where the rotor is stopped based on the positive and negative U-phase current, V-phase current, and W-phase current detected by the current detector; ,
The arithmetic / judgment control unit
By determining which of the positive U phase current, V phase current, and W phase current detected by the current detector is the largest, the rotational position where the rotor is stopped is It is determined that the corner is one of the first to third sections obtained by dividing the corner into three sections,
Further, when the largest positive phase current is smaller than the negative phase current of the same phase, the rotational position at which the rotor is stopped is the angle of the boundary between two sections different from the determined section And determine
Furthermore, in the determined section, when the largest positive phase current is larger than the negative phase current of the same phase, the difference between the largest phase current and the second largest phase current and the second largest phase current And a rotation position where the rotor is stopped is determined by referring to data in which the deviation and the rotation position are allocated in advance according to a deviation between the difference between the rotation current and the smallest phase current. A device for detecting an initial rotational position of a DC motor.   The current values of the U-phase current, V-phase current, and W-phase current in the positive and negative directions are 1.3 to 1.6 times the rated current of the brushless DC motor. Item 2. An initial rotational position detection device for a brushless DC motor according to Item 1.   3. The brushless DC motor initial rotational position detection device according to claim 1, wherein the deviation is 4 times or less, 4 times or more, or 32 times or more.     3. The initial rotational position detection of the brushless DC motor according to claim 1, wherein the deviation is a deviation of 2 times or less, 2 times or more, 4 times or more, 8 times or more, or 32 times or more. apparatus. The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. A method for detecting an initial rotational position of a brushless DC motor, which is used in a magnet-less brushless DC motor and detects a rotational position where the rotor is stopped,
Current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is magnetically saturated. As described above, a current is passed from the two windings to the one winding, and a pulse is applied to the stator winding so that the one winding is changed in order of U phase, V phase, and W phase. Supply voltage,
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. When the U-phase current, V-phase current, W-phase current, and the one winding are changed in sequence to the U-phase, V-phase, and W-phase, current is supplied from the two windings to the one winding. Detecting negative U-phase current, V-phase current, and W-phase current flowing in the one winding when flowing,
By determining which of the detected positive U-phase current, V-phase current, and W-phase current is the largest, the rotational position at which the rotor is stopped is divided into three electrical angles of 360 °. Is determined to be one of the first to third sections,
Further, when the largest positive phase current is smaller than the negative phase current of the same phase, the rotational position at which the rotor is stopped is the angle of the boundary between two sections different from the determined section And determine
Furthermore, in the determined section, when the largest positive phase current is larger than the negative phase current of the same phase, the difference between the largest phase current and the second largest phase current and the second largest phase current And a rotation position where the rotor is stopped is determined by referring to data in which the deviation and the rotation position are allocated in advance according to a deviation between the difference between the rotation current and the smallest phase current. A method for detecting an initial rotational position of a DC motor.   The current values of the U-phase current, V-phase current, and W-phase current in the positive and negative directions are 1.3 to 1.6 times the rated current of the brushless DC motor. Item 2. A method for detecting an initial rotational position of a brushless DC motor according to Item 1.   3. The method of detecting an initial rotational position of a brushless DC motor according to claim 1, wherein the deviation is 4 times or less, 4 times or more, or 32 times or more.     3. The initial rotational position detection of the brushless DC motor according to claim 1, wherein the deviation is a deviation of 2 times or less, 2 times or more, 4 times or more, 8 times or more, or 32 times or more. Method. The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. An initial rotational position detection device for a brushless DC motor, which is used in a magnetless brushless DC motor and detects a rotational position where the rotor is stopped,
A motor power supply for supplying current to the three-phase stator winding;
A current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is connected to U A pulse voltage drive control unit that performs control to supply a pulse voltage from the motor power supply unit to the stator winding so as to sequentially change the phase, the V phase, and the W phase;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. A current detector for detecting a U-phase current, a V-phase current, and a W-phase current,
A calculation / determination control unit that estimates the rotational position where the rotor is stopped based on the positive U phase current, V phase current, and W phase current detected by the current detector;
The arithmetic / judgment control unit
By determining which of the positive U phase current, V phase current, and W phase current detected by the current detector is the largest, the rotational position where the rotor is stopped is It is determined that the corner is one of the first to third sections obtained by dividing the corner into three sections,
Further, in the determined section, the value of this ratio is determined according to the value of the ratio between the difference between the largest phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current. An initial rotational position detection device for a brushless DC motor, wherein the rotational position at which the rotor is stopped is determined with reference to data that is assigned in advance to the rotational position. The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. A method for detecting an initial rotational position of a brushless DC motor, which is used in a magnet-less brushless DC motor and detects a rotational position where the rotor is stopped,
A current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding is connected to U Supplying a pulse voltage to the stator winding so as to change in order of phase, V phase, and W phase;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. Detect U phase current, V phase current, W phase current,
By determining which of the detected positive U-phase current, V-phase current, and W-phase current is the largest, the rotational position at which the rotor is stopped is divided into three electrical angles of 360 °. Is determined to be one of the first to third sections,
Further, in the determined section, the value of this ratio is determined according to the value of the ratio between the difference between the largest phase current and the second largest phase current and the difference between the second largest phase current and the smallest phase current. A method for detecting an initial rotational position of a brushless DC motor, wherein the rotational position at which the rotor is stopped is determined by referring to data in which the rotational position is allocated in advance. The stator core of the stator is provided with a U-phase winding, a V-phase winding, and a W-phase winding as three-phase stator windings, and a permanent magnet is embedded in the rotor core of the rotor. A method for detecting an initial rotational position of a brushless DC motor, which is used in a magnet-less brushless DC motor and detects a rotational position where the rotor is stopped,
Current is passed from the one winding to the remaining two windings so that one winding of the three-phase stator windings is not magnetically saturated. Supplying a pulse voltage to the stator winding so as to change in order of phase, V phase, and W phase;
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. Detect U phase current, V phase current, W phase current,
By determining which one of the detected positive U-phase current, V-phase current, and W-phase current is the largest, the rotational position at which the rotor is stopped has an electrical angle of 60 in each section. It is determined that it is one of three sections that are 60 ° apart from each other at an electrical angle of 60 °,
In each section, the value of the difference between the largest phase current and the second largest phase current is divided into a case where the difference is larger and smaller than a predetermined minute value, and the rotor stops in each section. Is determined to be a pre-set angle for each divided state,
Next, current is passed from the one winding to the remaining two windings so that one of the three-phase stator windings is magnetically saturated, and the one winding Current is passed from the two windings to the one winding so as to be magnetically saturated, and the one winding is changed in order of U phase, V phase, and W phase. Supply pulse voltage to the wire,
When the one winding is changed in order of U phase, V phase, and W phase, a positive direction flows through the one winding when current flows from the one winding to the remaining two windings. When the U-phase current, V-phase current, W-phase current, and the one winding are changed in sequence to the U-phase, V-phase, and W-phase, current is supplied from the two windings to the one winding. Detecting negative U-phase current, V-phase current, and W-phase current flowing in the one winding when flowing,
In each section, when the positive phase current is larger than the negative phase current, it is determined that the rotor is stopped at the determined angle, and the negative phase current is the positive phase current. A method for detecting an initial rotational position of a brushless DC motor, wherein when the current is smaller than the current, it is determined that the position where the rotor is stopped is an angle advanced by 180 ° from the determined angle.

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