JP2010045959A - Method of calculating motor characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for calculating motor characteristics by a method different from that in the prior art. <P>SOLUTION: A method of calculating motor characteristics includes a step of calculating the motor characteristics on the basis of an actual torque being a torque that a motor theoretically generates. The actual torque is configured by combining an external torque that a motor generates with respect to an external load and an internal torque that a motor generates with respect to an internal load. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for calculating the characteristics of an electric motor.

  Conventionally, when the characteristics of an electric motor are represented by a graph, the torque generated by the electric motor with respect to an external load is represented on the horizontal axis, and the characteristics of the electric motor are represented on the vertical axis (for example, Patent Document 1).

Japanese Patent Laid-Open No. 06-109564

  However, when the characteristics of the motor are calculated by the conventional method, when the motor is rotated with no load, the output and efficiency of the motor are set to 0 even though the motor is working to rotate the rotor. There was a problem of being calculated.

  In recent years, the number of rotors equipped with permanent magnets has increased, and the rotor itself has increased as a load. In addition, an increasing number of electric motors work directly with a single rotor. Therefore, even when only the rotor is rotating, there is a demand for calculating the efficiency of the motor, assuming that the motor is working. There has also been a need to calculate the number of revolutions in a zero-gravity space without mechanical loss.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a technique capable of calculating the characteristics of an electric motor by a method different from the conventional one.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  In order to solve at least a part of the problems described above, the present invention can take the following forms or application examples.

[Application Example 1]
A method for calculating the characteristics of an electric motor,
A step of calculating characteristics of the electric motor based on a true torque that is a torque that the electric motor can theoretically generate,
The true torque is
An external torque that the electric motor generates with respect to an external load;
The method is a combined torque of an internal torque generated by the electric motor with respect to an internal load.
In the method of Application Example 1, the rotor itself is regarded as a load by calculating the characteristics of the electric motor based on the true torque. Therefore, according to the method of the application example 1, it is possible to appropriately calculate the characteristics of the electric motor.

[Application Example 2]
A method described in application example 1,
A method of calculating a true output of the electric motor based on the true torque.
According to the method of Application Example 2, it is possible to appropriately calculate the output of the motor when the rotor itself is regarded as a load.

[Application Example 3]
A method described in application example 2,
A method of calculating the true output by multiplying a counter electromotive force and a current value.
According to the method of the application example 3, the output of the motor when the rotor itself is regarded as a load can be appropriately calculated from the electrical value.

[Application Example 4]
The method according to application example 2 or 3,
A method of calculating the true output so that a point where the true output indicates 0 and a point where the current value indicates 0 match.
According to the method of Application Example 4, it is possible to appropriately calculate the output of the electric motor when the rotor itself is regarded as a load. Furthermore, it can be set as the description which the point where the output of an electric motor shows 0, and the point where an electric current value shows 0 corresponded.

[Application Example 5]
A method described in application example 1,
A method of calculating a true efficiency of the electric motor based on the true torque.
According to the method of Application Example 5, the efficiency of the electric motor when the rotor itself is regarded as a load can be calculated appropriately.

[Application Example 6]
A method described in application example 5,
Calculating the true efficiency by the ratio of the back electromotive force to the supply voltage.
According to the method of the application example 6, the efficiency of the motor when the rotor itself is regarded as a load can be appropriately calculated from an electrical value.

[Application Example 7]
The method according to application example 5 or 6,
A method of calculating the true efficiency so that the true efficiency indicates 100% at a point where the current value indicates 0.
According to the method of Application Example 7, the efficiency of the electric motor when the rotor itself is regarded as a load can be appropriately calculated. Furthermore, the efficiency of the electric motor can be displayed at 100% even when the current value indicates 0.

[Application Example 8]
A method described in application example 1,
A method of calculating the number of revolutions of the electric motor based on the true torque.
According to the method of the application example 8, it is possible to appropriately calculate the rotation speed of the electric motor. It is also possible to calculate the rotational speed when the load of the rotor itself is zero.

[Application Example 9]
The method according to application example 8,
The method of calculating the said rotation speed by ratio of a counter electromotive force and a counter electromotive force constant.
According to the method of the application example 9, it is possible to appropriately calculate the rotation speed of the electric motor when the rotor itself is regarded as a load from an electrical value. It is also possible to calculate the rotational speed when the load of the rotor itself is zero.

[Application Example 10]
The method according to any one of Application Examples 1 to 9,
When the back electromotive force constant is Ke and the torque constant is Kt,
Ke = Kt
A method of calculating the characteristics of the electric motor using the following formula.
According to the method of Application Example 10, the characteristics of the electric motor can be calculated appropriately.

[Application Example 11]
A control device for an electric motor,
A resistance value of an electromagnetic coil of the electric motor;
A voltage value of a voltage supplied to the electric motor;
A current value at the time of no load of the electric motor;
The number of rotations of the electric motor when no load is applied;
A characteristic calculation unit for calculating the characteristic of the electric motor based on
A control unit for controlling the electric motor based on the calculated electric motor characteristics;
An electric motor control device.
According to the control device of application example 11, the electric motor can be appropriately controlled based on the characteristics of the electric motor.

[Application Example 12]
An electric motor,
An electric motor comprising the control device according to Application Example 11.
The electric motor of Application Example 12 is appropriately controlled based on the characteristics of the electric motor.

[Application Example 13]
A method for calculating the true efficiency of an electric motor,
(A) obtaining a back electromotive force generated in the electric motor;
(B) obtaining a voltage value of a voltage supplied to the electric motor;
(C) In the case where the back electromotive force is Eg, the voltage value is Es, and the true efficiency of the motor is ηr,
ηr = 100 × Eg / Es
Calculating the true efficiency ηr of the electric motor according to the equation:
A method comprising:
In the method of the application example 13, the rotor itself is regarded as a load, and the efficiency of the electric motor is calculated. For this reason, even when the electric motor is rotated with no load, the efficiency shows a non-zero value. Therefore, according to the method of application example 13, the efficiency of the electric motor can be calculated appropriately.

[Application Example 14]
A method described in application example 13,
In the step (c), when the back electromotive force at no load is Egnl and the true efficiency of the motor at no load is ηrnl,
ηrnl = 100 × Egnl / Es
A method comprising calculating a true efficiency ηrnl of the electric motor at no load according to the formula:
In the method of the application example 14, the efficiency of the motor when the motor is rotated with no load can be appropriately calculated. It can be evaluated that the electric motor with the efficiency at the time of no load being close to 100% is an electric motor having a smaller loss due to the rotor.

[Application Example 15]
The method according to any one of Application Examples 1 to 10, Application Example 13, and Application Example 14, wherein when the motor is PWM-driven, a value obtained by multiplying a supply voltage by a duty ratio is an effective voltage. The method to use as the value.
According to the method of application example 15, in the case of PWM driving, the characteristics of the motor under PWM driving can be easily calculated by using the effective voltage value multiplied by the duty ratio.

[Application Example 16]
The method according to any one of Application Example 1 to Application Example 10 and Application Example 13 to Application Example 15, wherein when the electromagnetic coil is three-phase star-connected, the total resistance of the electromagnetic coil of the electric motor is A method using a resistance value that is twice the resistance value of the electromagnetic coil alone.
According to the method of the application example 16, even when the electromagnetic coil of the motor is three-phase star-connected, the characteristics of the motor can be easily calculated.

  Note that the present invention can be realized in various modes. For example, the present invention can be realized in the form of a motor characteristic calculation method and apparatus, a motor characteristic calculation system, an integrated circuit for realizing the functions of the method or apparatus, a computer program, a recording medium on which the computer program is recorded, and the like. it can.

It is a schematic diagram which shows the structure of the electric motor used as the measuring object as one Example of this invention. It is a block diagram which shows the structure of the motor characteristic acquisition apparatus in 1st Example. It is a flowchart which shows the process of acquiring the characteristic of an electric motor. It is the graph which drew the characteristic of the motor with the conventional notation method, and the graph which drew the characteristic of the motor with the new notation method. It is a graph which shows the relationship between the true torque Tr which an electric motor can generate | occur | produce theoretically, and the electric current value I which flows into an electromagnetic coil. It is a graph which shows the relationship between the true torque Tr which an electric motor can generate | occur | produce theoretically, and the rotation speed N of an electric motor. It is a graph which shows the relationship between the true torque Tr which an electric motor can generate | occur | produce theoretically, and the true output Pr of an electric motor. It is a graph which shows the relationship between the true torque Tr which a motor can generate | occur | produce theoretically, and the true efficiency (eta) r of a motor. It is a table | surface which shows the result of having calculated the various characteristics of the electric motor. It is a graph which shows the relationship between the true torque Tr and the electric current value I based on the calculation result by FIG. 10 is a graph showing the relationship between the true torque Tr and the rotational speed N based on the calculation result according to FIG. 9. 10 is a graph showing a relationship between a true torque Tr and a true output Pr based on the calculation result according to FIG. 9. 10 is a graph showing the relationship between true torque Tr and true efficiency ηr based on the calculation result of FIG. 9. It is a flowchart which shows the procedure of the notation method of the graph by software. It is a block diagram which shows the structure of the motor characteristic acquisition apparatus in 2nd Example. It is explanatory drawing which shows the structure of an electric motor in consideration of the inductance of an electromagnetic coil. It is explanatory drawing which shows the supply voltage in PWM drive, and the electric current which flows into an electromagnetic coil. It is explanatory drawing which shows the modification of a 3rd Example. It is explanatory drawing which shows a 4th Example. It is explanatory drawing which shows the modification 6. FIG. It is explanatory drawing which shows the projector using the motor by the modification of this invention. It is explanatory drawing which shows the fuel cell type mobile telephone using the motor by the modification of this invention. It is explanatory drawing which shows the electric bicycle (electric assisted bicycle) as an example of the moving body using the motor / generator by the modification of this invention. It is explanatory drawing which shows an example of the robot using the motor by the modification of this invention. It is explanatory drawing which shows the rail vehicle using the motor by the modification of this invention.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Variation:
F. Application example:

A. First embodiment:
FIG. 1 is a schematic diagram showing a configuration of an electric motor 100 to be measured as one embodiment of the present invention. The electric motor 100 includes a rotor unit 10 having a permanent magnet, an electromagnetic coil 20, a PWM driver 22, a Hall IC 26, and a PWM control unit 28. Moreover, the electric motor 100 is connected to the power supply 24, and the supply voltage value Es [V] is supplied as a power supply voltage.

  The Hall IC 26 generates a sensor signal SSA corresponding to the rotational position of the rotor unit 10. The sensor signal SSA is supplied to the PWM control unit 28. The PWM control unit 28 switches the two switches S1 and S2 of the PWM driver 22 in accordance with the sensor signal SSA. As a result, the direction of the current flowing through the electromagnetic coil 20 is switched. Then, when the direction of the current flowing through the electromagnetic coil 20 is switched, the magnetization direction of the electromagnetic coil 20 is switched, and the rotor unit 10 can rotate. The electromagnetic coil 20 is simulated as an internal resistance 31 and a back electromotive force Eg. The counter electromotive force Eg [V] is generated in the direction opposite to the direction of the current flowing through the electromagnetic coil 20. The internal resistor 31 has a resistance value Rdc [Ω].

  In this embodiment, when the resistance value Rdc of the electromagnetic coil 20, the supply voltage value Es, the rotational speed Nnl [rpm] when the motor 100 is rotated without load, and the motor 100 when rotated without load. Various characteristics of the electric motor 100 are calculated by measuring the current value Inl [A] flowing through the electromagnetic coil 20. Here, the characteristics of the motor mean a back electromotive force constant Ke, a torque-current characteristic, a torque-rotational speed characteristic, a torque-work characteristic, a torque-efficiency characteristic, and the like. Further, in this specification, “no load” means a state in which an external load is not connected to the rotor unit 10.

  FIG. 2 is a block diagram showing the configuration of the motor characteristic acquisition device 200 in the first embodiment. The motor characteristic acquisition device 200 includes a rotation speed measurement unit 202, a resistance value measurement unit 204, a supply voltage value measurement unit 206, a current value measurement unit 208, and a calculation unit 210. The rotation speed measuring unit 202 is connected to the rotating shaft 102 of the electric motor 100 through a coupling 214. The rotational speed measuring unit 202 measures the rotational speed Nnl when the electric motor 100 is rotated without load. Hereinafter, the rotation speed Nnl when the electric motor 100 is rotated without load is also referred to as “no-load rotation speed Nnl”. The no-load rotation speed Nnl is supplied to the calculation unit 210.

  The supply voltage value measuring unit 206 measures the supply voltage value Es supplied to the electric motor 100 from the power supply 24 (FIG. 1). The current value measuring unit 208 measures a current value Inl flowing through the electromagnetic coil 20 (FIG. 1) when the electric motor 100 is rotated without a load. Hereinafter, the current value Inl flowing through the electromagnetic coil 20 when the electric motor 100 is rotated without load is also referred to as “no-load current value Inl”. The no-load current value Inl is supplied to the calculation unit 210.

  The resistance value measuring unit 204 measures the resistance value Rdc of the internal resistance 31 (FIG. 1) of the electromagnetic coil 20. The resistance value Rdc of the electromagnetic coil 20 can be obtained from the relationship between the current value I flowing through the electromagnetic coil 20 and the supply voltage value Es in a state where the back electromotive force Eg is not generated. At this time, it is preferable to control the current value I or the supply voltage value Es so that the resistance value Rdc is not affected by Joule heat. For example, the state where the back electromotive force Eg is not generated is fixed so that the rotor unit 10 is not rotated at the target mechanical angle position to stop the rotor unit 10 and the switches S1 and S2 of the PWM driver 22 are fixed. Can be realized. The measured resistance value Rdc is supplied to the calculation unit 210.

  The calculation unit 210 calculates the characteristics of the motor based on the resistance value Rdc, the supply voltage value Es, the no-load current value Inl, and the no-load rotation speed Nnl. This calculation method will be described later. The characteristics of the electric motor 100 calculated by the calculation unit 210 are displayed by the display device 212.

  FIG. 3 is a flowchart showing a process of acquiring the characteristics of the electric motor. In step S10, the resistance value Rdc of the electromagnetic coil 20 is measured. In step S20, the supply voltage value Es to the electric motor 100 is measured. In step S30, the rotational speed Nnl when the electric motor 100 is rotated with no load is measured. In step S40, the current value Inl is measured when the electric motor 100 is rotated with no load. In step S50, the characteristics of the electric motor 100 are calculated based on the resistance value Rdc, the supply voltage value Es, the no-load rotation speed Nnl, and the no-load current value Inl. A method for calculating the characteristics of the electric motor 100 will be described later.

  FIG. 4A is a graph depicting the characteristics of an electric motor by a conventional notation method. FIG. 4A shows the current value I, the rotational speed N, the output P, and the efficiency η. The horizontal axis in FIG. 4A is the torque T generated by the electric motor 100 with respect to the external load. In the conventional notation method shown in FIG. 4A, the output P is calculated as 0 at no load when the torque T = 0. As a result, in this conventional notation method, there is a problem that the efficiency η at the time of no load is calculated as 0% even though the electric motor 100 is working on the rotor portion 10 even at the time of no load. Arise. FIG. 4A shows the no-load rotation speed Nnl and the no-load current value Inl.

  FIG. 4B is a graph depicting the characteristics of the motor by a new notation method. The graph shown in FIG. 4B is drawn based on the idea that the electric motor 100 is working on the rotor unit 10 even when there is no load. For this reason, the horizontal axis of FIG. 4B is a true torque Tr different from the torque T. The axis of true torque Tr = Trnl corresponds to the conventional no-load point (torque T = 0). This true torque Tr will be described later. Further, FIG. 4B shows the true output Pr calculated with reference to the true torque Tr and the true efficiency ηr. The true output Pr indicates a value that is not 0 even when there is no load. Further, the true efficiency ηr indicates a value that is not 0% even when there is no load, and indicates 100% when the true torque Tr = 0. A method for calculating the true output Pr and the true efficiency ηr will be described later. In the present embodiment, the characteristics of the motor are calculated according to this new notation method. That is, the characteristics of the electric motor are calculated based on the true torque Tr. FIG. 4B shows the internal torque Trnl and the maximum torque Trmax in addition to the no-load rotation speed Nnl and the no-load current value Inl. Further, according to FIG. 4B, it can be understood that when the characteristics of the electric motor are calculated based on the true torque Tr, the point where the true output Pr indicates 0 and the point where the current value I indicates 0 coincide. . Furthermore, it can be understood that the true efficiency ηr indicates 100% at the point where the current value I indicates 0.

  FIG. 5 is a graph showing the relationship between the true torque Tr that can be theoretically generated by the electric motor 100 and the current value I flowing through the electromagnetic coil 20. FIG. 5 shows the maximum torque Trmax and the internal torque Trnl. The maximum torque Trmax is a starting torque generated by the electric motor 100 when the rotation speed N = 0. The internal torque Trnl is a torque generated by the electric motor 100 when the electric motor 100 is rotated with no load. The same applies to FIGS. 6 to 8.

  Here, “true torque Tr [N · m]” will be described. The rotor unit 10 of the electric motor 100 can be considered as an internal load of the electric motor 100. Therefore, the electric motor 100 generates an internal torque Trnl (hereinafter also referred to as a no-load true torque Trnl) and rotates the rotor unit 10 even when no external load is connected to the rotor unit 10. Can be considered. That is, when there is no load, the internal torque Trnl and the internal load (including mechanical loss) by the rotor unit 10 are balanced. The true torque Tr is a sum of the internal torque Trnl and torque generated by the rotor unit 10 with respect to the external load (hereinafter also referred to as external torque Tout). In other words, the true torque Tr is a theory of torque that the electric motor 100 can generate to the outside when the internal load of the rotor unit 10 is 0 (that is, the internal loss by the rotor unit 10 is 0). Value.

ここで、Ｋｔは、トルク定数である。トルク定数Ｋｔ［Ｎ・ｍ／Ａ］は、逆起電力定数Ｋｅ［Ｖ・ｓ／ｒａｄ］と同じ値とすることができる。以下では、逆起電力定数Ｋｅを用いて説明する。逆起電力定数Ｋｅは、以下の（２）式で示される。

ここで、ωｎｌは、無負荷で電動機１００を回転させた場合の角速度（以下では、無負荷角速度ωｎｌとも呼ぶ。）であり、Ｅｇｎｌは、無負荷で電動機１００を回転させた場合に電磁コイル２０に発生する逆起電力（以下では、無負荷逆起電力Ｅｇｎｌとも呼ぶ。）である。 The relationship between the true torque Tr [N · m] and the current value I [A] is expressed by the following equation (1).

Here, Kt is a torque constant. The torque constant Kt [N · m / A] can be set to the same value as the back electromotive force constant Ke [V · s / rad]. Below, it demonstrates using the back electromotive force constant Ke. The back electromotive force constant Ke is expressed by the following equation (2).

Here, ωnl is an angular velocity when the electric motor 100 is rotated with no load (hereinafter also referred to as a no-load angular velocity ωnl), and Egnl is an electromagnetic coil 20 when the electric motor 100 is rotated with no load. The back electromotive force generated in the above (hereinafter also referred to as no-load back electromotive force Egnl).

また、（２）式における無負荷逆起電力Ｅｇｎｌは、電圧の釣り合いより、以下の（４）式で示される。

ここで、（３）、（４）式を、（２）式に代入すると、以下の（５）式となる。

（５）式から理解できるように、逆起電力定数Ｋｅ（＝トルク定数Ｋｔ）は、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌと、無負荷回転数Ｎｎｌとを測定することによって求めることができる。また、（４）式から理解できるように、無負荷逆起電力Ｅｇｎｌは、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌとを測定することによって求めることができる。 The no-load angular velocity ωnl [rad / s] in the equation (2) is expressed by the following equation (3) using the no-load rotation speed Nnl [rpm].

Further, the no-load back electromotive force Egnl in the equation (2) is represented by the following equation (4) from the balance of the voltage.

Here, when the expressions (3) and (4) are substituted into the expression (2), the following expression (5) is obtained.

As can be understood from the equation (5), the back electromotive force constant Ke (= torque constant Kt) measures the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl. Can be determined by Further, as can be understood from the equation (4), the no-load back electromotive force Egnl can be obtained by measuring the supply voltage value Es, the resistance value Rdc, and the no-load current value Inl.

（６）式から理解できるように、真トルクＴｒと電流値Ｉとの関係は、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌと、無負荷回転数Ｎｎｌとを測定することによって求めることができる。 Further, when the formula (5) is substituted into the formula (1), the following formula (6) is obtained.

As can be understood from the equation (6), the relationship between the true torque Tr and the current value I is that the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured. Can be obtained.

Further, as shown in FIG. 5, when the horizontal axis is represented by true torque Tr, the graph passes through the origin. Further, the no-load state is indicated by the position of the no-load true torque Trnl. The same applies to FIGS. 6 to 8 described below. The no-load true torque Trnl can be obtained by the following equation (7) obtained by modifying the equation (6).

（８）式における逆起電力Ｅｇは、電圧の釣り合いより、以下の（９）式で示される。

また、角速度ωと、回転数Ｎとの関係は、以下の（１０）式で示される。

（８）、（９）式を（１０）式に代入して変形すると、以下の（１１）式となる。

（１１）式から理解できるように、機械的な回転数Ｎは、逆起電力Ｅｇと逆起電力定数Ｋｅとの比によって算出することができる。さらに、回転数Ｎは、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、電流値Ｉと、逆起電力定数Ｋｅとにより、電気的に算出することもできる。 FIG. 6 is a graph showing the relationship between the true torque Tr that can be theoretically generated by the electric motor 100 and the rotational speed N of the electric motor 100. First, the angular velocity ω is expressed by the following equation (8) using the back electromotive force constant Ke.

The back electromotive force Eg in the equation (8) is represented by the following equation (9) from the balance of voltage.

Further, the relationship between the angular velocity ω and the rotation speed N is expressed by the following equation (10).

When the equations (8) and (9) are substituted into the equation (10) and transformed, the following equation (11) is obtained.

As can be understood from the equation (11), the mechanical rotational speed N can be calculated by the ratio of the counter electromotive force Eg and the counter electromotive force constant Ke. Further, the rotation speed N can be electrically calculated from the supply voltage value Es, the resistance value Rdc, the current value I, and the counter electromotive force constant Ke.

（１２）式から理解できるように、真トルクＴｒと回転数Ｎとの関係は、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌと、無負荷回転数Ｎｎｌとを測定することによって求めることができる。 When the equation (11) is modified using the equations (1) and (5), the following equation (12) is obtained.

As can be understood from the equation (12), the relationship between the true torque Tr and the rotation speed N is that the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured. Can be obtained.

ここで、（１９）式を用いて（１２）式を変形すると、以下の（１４）式となる。

（１４）式を（１３）式に代入すると、以下の（１５）式となる。

（１５）式から理解できるように、真トルクＴｒと真出力Ｐｒとの関係は、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌと、無負荷回転数Ｎｎｌとを測定することによって求めることができる。また、図７によれば、無負荷時においても、真出力Ｐｒは０ではないことが理解できる。すなわち、電動機１００は、無負荷時においても、ローター部１０に対して仕事をしていることが理解できる。 FIG. 7 is a graph showing the relationship between the true torque Tr that can be theoretically generated by the electric motor 100 and the true output Pr of the electric motor 100. The relationship between the true torque Tr [N · m] and the true output Pr [W] is expressed by the following equation (13).

Here, when the equation (12) is transformed using the equation (19), the following equation (14) is obtained.

Substituting equation (14) into equation (13) yields the following equation (15).

As can be understood from the equation (15), the relationship between the true torque Tr and the true output Pr is that the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured. Can be obtained. Further, according to FIG. 7, it can be understood that the true output Pr is not 0 even when there is no load. That is, it can be understood that the electric motor 100 is working on the rotor unit 10 even when there is no load.

（１６）式に、（１）、（１３）式を代入して変形すると、以下の（１７）式となる。

（１７）式に、（８）式を代入すると、以下の（１８）式となる。

（１８）式から理解できるように、真効率ηｒは、逆起電力Ｅｇと供給電圧値Ｅｓとの比によって示される。すなわち、真効率ηｒは、逆起電力Ｅｇと供給電圧値Ｅｓとを取得し、（１８）式で示される演算をすることによって、算出することができる。また、（１６）式と、（１８）式から以下の（１９）式が得られる。

この（１９）式を変形すると、以下の（２０）式となる。

（２０）式から理解できるように、真出力Ｐｒは、逆起電力Ｅｇと電流値Ｉとを乗算することにより算出することができる。
（２０）式に、（９）式を代入すると、以下の（２１）式となる。

（２１）式から理解できるように、機械的な真出力Ｐｒは、電気的に算出することもできる。すなわち、真出力Ｐｒは、抵抗値Ｒｄｃと、電流値Ｉと、供給電圧値Ｅｓとから算出することもできる。 FIG. 8 is a graph showing the relationship between the true torque Tr that can be theoretically generated by the electric motor 100 and the true efficiency ηr of the electric motor 100. Here, the true efficiency ηr [%] is calculated when it is considered that the electric motor 100 is working on the rotor unit 10 even when the electric motor 100 is rotating with no load. Efficiency. The true efficiency ηr is expressed by the following equation (16).

When the equations (1) and (13) are substituted into the equation (16) and transformed, the following equation (17) is obtained.

Substituting equation (8) into equation (17) yields the following equation (18).

As can be understood from the equation (18), the true efficiency ηr is represented by a ratio between the back electromotive force Eg and the supply voltage value Es. That is, the true efficiency ηr can be calculated by obtaining the back electromotive force Eg and the supply voltage value Es and performing the calculation represented by the equation (18). Moreover, the following (19) Formula is obtained from (16) Formula and (18) Formula.

When this equation (19) is modified, the following equation (20) is obtained.

As can be understood from the equation (20), the true output Pr can be calculated by multiplying the counter electromotive force Eg and the current value I.
Substituting equation (9) into equation (20) yields the following equation (21).

As can be understood from the equation (21), the mechanical true output Pr can also be calculated electrically. That is, the true output Pr can be calculated from the resistance value Rdc, the current value I, and the supply voltage value Es.

（２２）式から理解できるように、真トルクＴｒと真効率ηｒとの関係は、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌと、無負荷回転数Ｎｎｌとを測定することによって求めることもできる。また、真トルクＴｒと真効率ηｒとの関係は直線状となり、無負荷時においても、真効率ηｒは０ではないことが理解できる。すなわち、従来の算出方法による効率とは異なり、無負荷時であっても、電動機１００の真効率ηｒは低下しないことが理解できる。さらに、真トルクＴｒ＝０の場合には、真効率ηｒ＝１００［％］となることも理解できる。 Further, when the equation (18) is transformed using the equations (6) and (9), the following equation (22) is obtained.

As can be understood from the equation (22), the relationship between the true torque Tr and the true efficiency ηr is that the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured. Can also be obtained. Further, the relationship between the true torque Tr and the true efficiency ηr is linear, and it can be understood that the true efficiency ηr is not 0 even when there is no load. That is, it can be understood that the true efficiency ηr of the electric motor 100 does not decrease even when there is no load, unlike the efficiency by the conventional calculation method. It can also be understood that the true efficiency ηr = 100 [%] when the true torque Tr = 0.

（２３）式から理解できるように、無負荷真効率ηｒｎｌは、供給電圧値Ｅｓと、抵抗値Ｒｄｃと、無負荷電流値Ｉｎｌとを測定することによって求めることができる。また、無負荷真効率ηｒｎｌは、０ではない値を示す。この無負荷真効率ηｒｎｌは、無負荷時においても電動機１００はローター部１０に対して仕事をしていると考えた場合の効率である。この無負荷真効率ηｒｎｌが１００％に近い電動機ほど、ローター部による損失が小さい電動機であると評価することができる。なお、無負荷真効率ηｒｎｌは、無負荷時における無負荷逆起電力Ｅｇｎｌと、供給電圧値Ｅｓとを測定することによって求めることもできる。 Here, the case where the electric motor 100 is rotated with no load will be considered. True efficiency ηrnl at no load (hereinafter also referred to as no-load true efficiency ηrnl) is expressed by the following equation (23) obtained by substituting equation (7) into equation (22).

As can be understood from the equation (23), the no-load true efficiency ηrnl can be obtained by measuring the supply voltage value Es, the resistance value Rdc, and the no-load current value Inl. Further, the no-load true efficiency ηrnl indicates a non-zero value. The no-load true efficiency ηrnl is an efficiency when it is considered that the electric motor 100 is working on the rotor unit 10 even when there is no load. It can be evaluated that an electric motor having a no-load true efficiency ηrnl close to 100% has a smaller loss due to the rotor portion. The no-load true efficiency ηrnl can also be obtained by measuring the no-load back electromotive force Egnl at the time of no load and the supply voltage value Es.

  Further, if Pr = 0 and I = 0 are substituted into the above equation (16), ηr = 0/0, which is considered to be indefinite in mathematics. However, in practice, the expression (16) can be completely replaced by the expression (18), so that it can be proved that ηr = 0/0 holds as 1.

FIG. 9 is a table showing the results of calculating various characteristics of the electric motor 100. This FIG. 9 has shown the calculation result about the case where the measurement result shown below is obtained.
Supply voltage value Es = 20 [V]
Resistance value Rdc = 80 [Ω]
No-load current value Inl = 0.003 [A]
No-load rotation speed Nnl = 1538 [rpm]
The back electromotive force constant Ke is calculated to the following value based on the above four values.
Back electromotive force constant Ke = 0.123 [V · s / rad]
Based on the back electromotive force constant Ke, the current value I [A], the back electromotive force Eg [V], the angular velocity ω [rad], the rotation speed N [rpm], the true output Pr [W], The true efficiency ηr [%] is calculated for each true torque Tr [N · m]. The no-load true torque Trnl is calculated to the following value based on the back electromotive force constant Ke and the no-load current value Inl.
No-load true torque Trnl = 0.00037 [N · m]

  FIG. 10 is a graph showing the relationship between the true torque Tr and the current value I based on the calculation result shown in FIG. In FIG. 10, a straight line indicating the value of the no-load true torque Trnl is drawn. That is, the characteristic of the electric motor 100 at the time of no load is shown by the intersection of this straight line and the graph. The same applies to FIGS. 11 to 13 described below.

  FIG. 11 is a graph showing the relationship between the true torque Tr and the rotational speed N based on the calculation result shown in FIG. FIG. 12 is a graph showing the relationship between the true torque Tr and the true output Pr based on the calculation result shown in FIG. FIG. 13 is a graph showing the relationship between the true torque Tr and the true efficiency ηr based on the calculation result shown in FIG.

  As described above, in this embodiment, the rotor unit 10 is regarded as a load of the electric motor 100, and the true efficiency ηr is calculated based on the true torque Tr. According to this true efficiency ηr, the efficiency of the electric motor 100 can be appropriately evaluated.

  Various characteristics of the electric motor 100 can be calculated by measuring the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl. Further, in the case of a brushless motor, when the drive control method is changed, it is possible to calculate new characteristics after the change by measuring the above four values again.

ステップＳ１２０では、無負荷角速度ωｎｌを、以下の（２５）式にしたがって算出する。

ステップＳ１３０では、無負荷逆起電力Ｅｇｎｌを、以下の（２６）式にしたがって算出する。

ステップＳ１４０では、逆起電力定数Ｋｅを、以下の（２７）式にしたがって算出する。

FIG. 14 is a flowchart showing a procedure of a graph notation method by software. In step S110, a current value Ist at the time of starting the motor (hereinafter also referred to as a starting current value Ist) is calculated according to the following equation (24).

In step S120, the no-load angular velocity ωnl is calculated according to the following equation (25).

In step S130, the no-load back electromotive force Egnl is calculated according to the following equation (26).

In step S140, the back electromotive force constant Ke is calculated according to the following equation (27).

ステップＳ１６０では、最大トルクＴｒｍａｘを、以下の（２９）式にしたがって算出する。

In step S150, the torque constant Kt is calculated according to the following equation (28).

In step S160, the maximum torque Trmax is calculated according to the following equation (29).

In step S170, the array value of the true torque Tr [i] is determined by the following flow using the decomposition number Nt of the true torque Tr.
Tstp = Trmax / (Nt-1);
n = 0;
while (n <Nt) {
Tr [n] = n × Tstp;
n ++;
}

In step S180, array values of various characteristics are determined according to the following flow.
i = 0;
while (i <Nt) {
Array of current values I [i] = Tr [i] / Kt;
Arrangement of back electromotive force Eg [i] = Es−Rdc × I [i];
Arrangement of rotational speed N [i] = 60 / (2 × π) × Eg [i] / Ke;
True output array Pr [i] = Eg [i] / Ke × Tr [i];
Array of power values Pe [i] = Es × I [i];
True efficiency array ηr [i] = Eg [i] / Es × 100;
i ++;
}
Maximum power value Pemax = Es × Ist;
Theoretical rotational value Nmax = N [0];
Internal torque Trnl = Kt × Inl;

  In step S190, the graph shown in FIG. 4B is written based on the determined array value. According to the above procedure, the graph according to the new notation method shown in FIG. 4B can be represented by software.

B. Second embodiment:
FIG. 15 is a block diagram showing a configuration of the motor characteristic acquisition device 300 in the second embodiment. The difference from the motor characteristic acquisition device 200 shown in FIG. 2 is that a driving motor 302 and a back electromotive force measurement unit 304 are provided. The calculation unit 210 in the motor characteristic acquisition device 300 calculates the back electromotive force constant Ke as follows.

逆起電力定数Ｋｅを算出した後は、演算部２１０は、第１実施例と同様に、電動機１００の特性を算出する。 First, the electric motor 100 to be measured is set to a state where no voltage is applied. Then, the drive motor 302 rotates the rotating shaft 102 of the motor 100 to be measured. As a result, a back electromotive force Eg is generated in the electromagnetic coil 20 (FIG. 1) of the electric motor 100. The counter electromotive force measuring unit 304 measures the counter electromotive force Eg and supplies it to the computing unit 210. The rotation speed measurement unit 202 measures the rotation speed N of the electric motor 100 and supplies it to the calculation unit 210. The calculation unit 210 converts the rotational speed N into an angular velocity ω, and calculates a back electromotive force constant Ke according to the following equation (30).

After calculating the back electromotive force constant Ke, the arithmetic unit 210 calculates the characteristics of the electric motor 100 as in the first embodiment.

  It is also possible to create a graph in which the horizontal axis represents the angular velocity ω and the vertical axis represents the back electromotive force Eg, and the back electromotive force constant Ke can be calculated from the slope. In this case, it is preferable to measure the back electromotive force Eg for each of the plurality of angular velocities ω and create a graph that approximates the plurality of points using the least square method.

  Further, in the motor characteristic acquisition device 300 in the second embodiment, the counter electromotive force measuring unit 304 measures the counter electromotive force Eg. For this reason, the calculating part 210 can also calculate true efficiency (eta) r based on the back electromotive force Eg and the supply voltage value Es according to (18) Formula.

C. Third embodiment:
In the first and second embodiments, the case where the duty ratio is 1 has been described. In the third embodiment, the case where the electric motor 100 is PWM-driven with the duty ratio Dr (0 <Dr <1) will be described. When the duty ratio Dr is not 1, there is a period in which the voltage supply to the electromagnetic coil 20 is turned on and a period in which the voltage is turned off, so that the current changes. Since the electric motor 100 includes the electromagnetic coil 20, it is necessary to consider the induced electromotive force of the electromagnetic coil 20 due to a change in current in PWM driving.

  FIG. 16 is an explanatory diagram illustrating the configuration of the electric motor in consideration of the inductance of the electromagnetic coil. The electric motor shown in FIG. 16 is the same as the electric motor shown in FIG. 1 except that the inductance L of the electromagnetic coil 20 is shown in FIG.

  FIG. 17 is an explanatory diagram showing a supply voltage in PWM driving and a current flowing through the electromagnetic coil. Here, the duty ratio of the supply voltage Es is Dr, and the length of the duty control period is U. At this time, a period from time 0 to time Dr × U is a period in which voltage supply is on. When the supply of voltage changes from off to on, the maximum current does not flow suddenly through the electromagnetic coil 20, but the current gradually increases. A period from time Dr × U to time U is a period in which voltage supply is off. Similarly, when the voltage supply changes from on to off, the current flowing through the electromagnetic coil 20 does not suddenly become zero but gradually decreases.

The circuit equation of the electric motor 100 is established by dividing the supply of voltage to the electromagnetic coil 20 into an on period and an off period. During the period when the voltage supply to the electromagnetic coil 20 is on (0 ≦ t ≦ Dr × U), the circuit equation of the electric motor 100 is expressed by the equation (31). This expression (31) is an expression obtained by modifying the expression (4) of the first embodiment and adding an induced electromotive force by the electromagnetic coil 20.

Solving equation (31) yields equation (32).

Here, a specific value of the constant A can be obtained by defining a boundary condition. However, since the value of the constant A is canceled by the later calculation and disappears, it is left as A here. Next, a circuit equation is established during a period in which the voltage supply to the electromagnetic coil 20 is off (Dr × U ≦ t ≦ U). In this case, the circuit equation of the electric motor 100 is Es = 0 in the equation (31). Specifically, the equation is as shown in equation (33).

Solving equation (33) yields equation (34). Note that the value of the constant B can be obtained in the same manner. However, as with the value of the constant A, it is canceled out by a later calculation and disappears.

Here, Expression (36) is obtained by the boundary condition shown in Expression (35). This boundary condition is due to the coincidence of the end point of equation (32) and the start point of equation (34).

When formula (36) is modified, formula (37) is obtained.

Further, the equation (39) is obtained by the boundary condition shown in the equation (38). Similarly, when the equation (39) is modified, the equation (40) is obtained. This boundary condition is due to the coincidence of the start point of equation (32) and the end point of equation (34).

Next, the average current of the electric motor 100 is obtained. The average current I can be calculated by the equation (41).

The numerator first term of equation (41) can be transformed as in equation (42), and the numerator second term can be transformed as in equation (43).

Here, when the first term of the equation (42) and the first term of the equation (43) are added, the equation (44) is obtained.

Substituting the equations (37) and (40) into the equation (44) yields the equation (45).

Next, when the second term of the equation (42) and the second term of the equation (43) are added, the equation (46) is obtained.

As a result, equation (41) can be transformed into equation (47). As can be seen from the equation (47), the constants A and B in the equations (32) and (34) are offset and disappear.

As apparent from the equation (47), the inductance L of the electromagnetic coil 20 does not appear in the equation (47). This reflects a characteristic of the electromagnetic coil 20 as an inductance. That is, in a circuit including an electromagnetic coil, energy is accumulated in the electromagnetic coil 20 when the voltage supply is on, and conversely, when the voltage supply is off, energy is released from the electromagnetic coil 20 conversely. Considering one cycle of PWM, the amount of energy stored in the electromagnetic coil 20 when the voltage supply is on and the amount of energy released from the electromagnetic coil 20 when the voltage supply is off may be the same. I understand. Thus, energy is not consumed in the electromagnetic coil 20 due to the inductance component. The effect of the inductance L of the electromagnetic coil 20 needs to be considered only when the voltage supply is on or only when the voltage supply is off, but is offset when one cycle of PWM driving is considered. Therefore, there is no need to consider. As a result, it is not necessary to consider the value of L under PWM driving, and the duty ratio Dr may be considered instead. When formula (47) is transformed, formula (48) is obtained.

  Compared with equation (9), equation (48) differs from equation (9) only in that the supply voltage is Es in equation (9) but Es × Dr in equation (48). is there. That is, by setting Es in the first embodiment to Es × Dr, it is possible to obtain various characteristics of the electric motor 100 under PWM drive. Similarly, equations other than equation (9) may be equations obtained by replacing the voltage Es with Es × Dr under PWM driving.

  As described above, the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured, and the supply voltage value Es multiplied by the duty ratio Dr as the supply voltage value Es × By using Dr as a new supply voltage value, it is possible to calculate various characteristics of the electric motor 100 under PWM drive.

C2. Modification of the third embodiment:
FIG. 18 shows a modification of the third embodiment. Here, there are two drive pulses in one electrical angle. Here, a value obtained by dividing the drive pulse ON period (D1 × U + (D3 × U−D2 × U) by the electrical angle period U is referred to as a duty ratio Dr. The duty ratio is D1 + (D3−D2). Become.

Similarly to the third embodiment, when divided into four periods on and off, equations in each period are established, and currents in each period are obtained, equations (49) to (52) are obtained. Note that the values of the constants A to D can be specifically obtained by determining the boundary conditions. However, as in the case of the third embodiment, the values are canceled by later calculations. Leave it as it is.

End point of equation (49) = start point of equation (50) (all t = D1U), end point of equation (50) = start point of equation (51) (both t = D2U), end point of equation (51) = ( 52) From the four boundary conditions of the start point of equation (t = D3U), the start point of equation (49) (t = 0) = the end point of equation (52) (t = U), 56) is obtained.

The average current I can be expressed by equation (57).

The first to fourth terms on the right-hand side of the equation (57) can be transformed as the equations (58) to (61), respectively.

When the first term of the equations (58) to (61) is added and then transformed, and the results of the equations (53) to (56) are substituted, the equation (62) is obtained. That is, the sum obtained by adding the first term of the equations (58) to (61) becomes zero.

When the second term of the equations (58) to (61) is added, the equation (63) is obtained.

Therefore, the average current I can be expressed by equation (64).

  The result of equation (64) is the same as the result of equation (47). Here, the case where there are two pulses in one cycle of the electrical angle has been described, but the case where there are three or more pulses can be considered similarly. That is, the expression (64) can be applied. In FIG. 18B, the current values at the points (points W, X, Y, Z) where the current graphs in each section intersect are schematically shown as the same, but these graphs are drawn schematically. The value of the current at point fluctuates depending on the values of D1 to D3.

D. Fourth embodiment:
FIG. 19 is an explanatory diagram showing the fourth embodiment. In the fourth embodiment, as shown in FIG. 19A, the three electromagnetic coils 20 of the electric motor are star-connected. Here, the three terminals of the star connection are referred to as terminals Vu, Vv, and Vw, respectively. FIG. 19B is an explanatory diagram illustrating voltages applied to the terminals Vu, Vv, and Vw. FIG. 19C is an explanatory diagram showing the period Q3 in FIG. 19B in an enlarged manner.

  In the periods T2 and T4 shown in FIG. 19C, the voltage Es is applied between the terminals Vu and Vv in FIG. 19A, and the terminal Vw is in a high impedance state. The current flows from the terminal Vu to the terminal Vv. When the internal resistance of the electromagnetic coil 20 is Rdc, the combined resistance between the terminal Vu and the terminal Vv is 2Rdc. In the period T3, the voltage Es is applied between the terminals Vu and Vw, and the terminal Vv has a high impedance. The current flows from the terminal Vu to the terminal Vw. The combined resistance between the terminal Vu and the terminal Vw is 2Rdc. In the periods T1 and T5, both terminals are in high impedance, and no current flows through any of the terminals Vu, Vv, and Vw.

In such a three-phase PWM drive, as the supply voltage value, as shown in the third embodiment, Es × Dr obtained by multiplying the supply voltage Es by the duty ratio Dr can be used instead. Further, 2Rdc can be used instead as the resistance value of the electromagnetic coil. For example, the formula (9) used in the first embodiment becomes the formula (65). The same applies to other equations.

  Here, the combined resistance value 2Rdc can be obtained from the relationship between the current value I flowing in the electric motor 100 and the supply voltage value Es in a state where the back electromotive force Eg is not generated. Specifically, in the state where the back electromotive force Eg is not generated, for example, the rotor unit 10 (see FIG. 1) is fixed so as not to rotate, and the state shown in the period T2 in FIG. 19C is maintained. This can be realized. The resistance value calculated at this time is the combined resistance 2Rdc.

  As described above, even in the three-phase PWM drive, the supply voltage value Es, the resistance value 2Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured, whereby various types of the electric motor 100 under the PWM drive are measured. It is possible to calculate the characteristics.

E. Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

E1. Modification 1:
In the above embodiment, the supply voltage value measuring unit 206 measures the supply voltage value Es. However, when the voltage value of the power supplied to the electric motor 100 is known, the supply voltage value Es is measured. Alternatively, the supply voltage value Es that has been found may be supplied to the calculation unit 210. That is, the motor characteristic acquisition device 200 may acquire the supply voltage value Es.

E2. Modification 2:
In the above embodiment, the resistance value measuring unit 204 measures the resistance value Rdc. However, when the resistance value of the electromagnetic coil 20 is known, the resistance value is known without measuring the resistance value Rdc. The value Rdc may be supplied to the calculation unit 210. That is, the motor characteristic acquisition device 200 may acquire the resistance value Rdc.

E3. Modification 3:
In the above embodiment, the rotation speed measuring unit 202 measures the rotation speed of the electric motor 100 as the rotation speed N [rpm]. However, the rotational speed measurement unit 202 may measure the rotational speed of the electric motor 100 as the angular speed ω [rad / s] and supply the angular speed ω to the calculation unit 210.

E4. Modification 4:
When the calculation of the characteristics of the electric motor is realized by a computer program, the supply voltage value Es, the resistance value Rdc, the no-load current value Inl, and the no-load rotation speed Nnl are measured in advance and obtained 4 One value may be acquired by a computer program. Alternatively, the supply voltage value Es and the back electromotive force Eg may be measured in advance, and the two obtained values may be acquired by the computer program.

E5. Modification 5:
In the first embodiment, four values (supply voltage value Es, resistance value Rdc, no-load current value Inl, no-load rotation speed Nnl) are measured, and characteristics such as efficiency of the electric motor 100 are calculated. Instead of this, other electrical values may be measured, and the characteristics of the electric motor 100 may be calculated from the measured values.

E6. Modification 6:
FIG. 20 is an explanatory diagram showing a sixth modification. The present invention is also applicable to a motor control device. That is, the motor control device may include a characteristic calculation unit (calculation unit 210) that calculates the characteristics of the motor and a control unit 213 that controls the motor based on the calculated characteristics of the motor. For example, the characteristic calculation unit calculates the characteristic of the electric motor based on the resistance value Rdc, the supply voltage value Es, the no-load current value Inl, and the no-load rotation speed Nnl. According to such a control device, it is possible to appropriately control the electric motor. An electric motor provided with this control device can also be realized.

F. Application example:
The present invention is applicable to various devices. For example, the present invention can be applied to motors of various devices such as a fan motor, a clock (hand drive), a drum type washing machine (single rotation), a roller coaster, and a vibration motor. When the present invention is applied to a fan motor, the various effects described above (low power consumption, low vibration, low noise, low rotation unevenness, low heat generation, long life) are particularly remarkable. Such fan motors are, for example, digital display devices, in-vehicle devices, fuel cell personal computers, fuel cell digital cameras, fuel cell video cameras, fuel cell devices such as fuel cell phones, projectors, etc. Can be used as a fan motor for equipment. The motor of the present invention can also be used as a motor for various home appliances and electronic devices. For example, the motor according to the present invention can be used as a spindle motor in an optical storage device, a magnetic storage device, a polygon mirror driving device, or the like. The motor according to the present invention can also be used as a motor for a moving body or a robot.

  FIG. 21 is an explanatory diagram showing a projector using a motor according to a modification of the present invention. The projector 3100 includes three light sources 3110R, 3110G, and 3110B that emit red, green, and blue color lights, and three liquid crystal light valves 3140R, 3140G, and 3140B that modulate these three color lights, respectively. A cross dichroic prism 3150 that synthesizes the modulated three-color light, a projection lens system 3160 that projects the combined three-color light onto the screen SC, a cooling fan 3170 that cools the inside of the projector, and a projector 3100 And a control unit 3180 for controlling the whole. As the motor for driving the cooling fan 3170, the various brushless motors described above can be used.

  22A to 22C are explanatory views showing a fuel cell type mobile phone using a motor according to a modification of the present invention. FIG. 22A illustrates an appearance of the mobile phone 3200, and FIG. 22B illustrates an example of an internal configuration. The mobile phone 3200 includes an MPU 3210 that controls the operation of the mobile phone 3200, a fan 3220, and a fuel cell 3230. The fuel cell 3230 supplies power to the MPU 3210 and the fan 3220. The fan 3220 is used to blow air from the outside of the mobile phone 3200 to supply air to the fuel cell 3230 or to discharge moisture generated by the fuel cell 3230 from the inside of the mobile phone 3200 to the outside. It is. Note that the fan 3220 may be disposed on the MPU 3210 as shown in FIG. 22C to cool the MPU 3210. As the motor for driving the fan 3220, the various brushless motors described above can be used.

  FIG. 23 is an explanatory diagram showing an electric bicycle (electric assist bicycle) as an example of a moving body using a motor / generator according to a modification of the present invention. In this bicycle 3300, a motor 3310 is provided on the front wheel, and a control circuit 3320 and a rechargeable battery 3330 are provided on a frame below the saddle. The motor 3310 assists traveling by driving the front wheels using the electric power from the rechargeable battery 3330. Further, the electric power regenerated by the motor 3310 is charged in the rechargeable battery 3330 during braking. The control circuit 3320 is a circuit that controls driving and regeneration of the motor. As the motor 3310, the above-described various brushless motors can be used.

  FIG. 24 is an explanatory diagram showing an example of a robot using a motor according to a modification of the present invention. The robot 3400 includes first and second arms 3410 and 3420 and a motor 3430. This motor 3430 is used when horizontally rotating the second arm 3420 as a driven member. As the motor 3430, the above-described various brushless motors can be used.

  FIG. 25 is an explanatory view showing a railway vehicle using a motor according to a modification of the present invention. The railway vehicle 3500 has a motor 3510 and wheels 3520. The motor 3510 drives the wheel 3520. Further, the motor 3510 is used as a generator during braking of the railway vehicle 3500 to regenerate electric power. As the motor 3510, the above-described various brushless motors can be used.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Rotor part 20 ... Electromagnetic coil 22 ... PWM driver 24 ... Power supply 26 ... Hall IC
DESCRIPTION OF SYMBOLS 28 ... PWM control part 31 ... Internal resistance 100 ... Electric motor 102 ... Rotating shaft 200 ... Electric motor characteristic acquisition apparatus 202 ... Rotational speed measurement part 204 ... Resistance value measurement part 206 ... Supply voltage value measurement part 208 ... Current value measurement part 210 ... Calculation Reference numeral 212: Display device 213: Control unit 214: Coupling 300: Motor characteristic acquisition device 302 ... Driving motor 304 ... Back electromotive force measurement unit 3100 ... Projector 3110 ... Light source 3140 ... Liquid crystal light valve 3150 ... Cross dichroic prism 3160 ... Projection Lens system 3170 ... Cooling fan 3180 ... Control unit 3200 ... Mobile phone 3220 ... Fan 3230 ... Fuel cell 3300 ... Bicycle 3310 ... Motor 3320 ... Control circuit 3330 ... Rechargeable battery 3400 ... Robot 3410 ... First arm 3420 ... Second arm 3430 ... motor 3500 ... railway vehicle 3510 ... motor 3520 ... the wheels

Claims (20)

A method for calculating the characteristics of an electric motor,
A step of calculating characteristics of the electric motor based on a true torque that is a torque that the electric motor can theoretically generate,
The true torque is
An external torque that the electric motor generates with respect to an external load;
The method is a combined torque of an internal torque generated by the electric motor with respect to an internal load. The method of claim 1, comprising:
A method of calculating a true output of the electric motor based on the true torque. The method of claim 2, comprising:
A method of calculating the true output by multiplying a counter electromotive force and a current value. The method according to claim 2 or 3, wherein
A method of calculating the true output so that a point where the true output indicates 0 and a point where the current value indicates 0 match. The method of claim 1, comprising:
A method of calculating a true efficiency of the electric motor based on the true torque. 6. A method according to claim 5, wherein
Calculating the true efficiency by the ratio of the back electromotive force to the supply voltage. The method according to claim 5 or 6, comprising:
A method of calculating the true efficiency so that the true efficiency indicates 100% at a point where the current value indicates 0. The method of claim 1, comprising:
A method of calculating the number of revolutions of the electric motor based on the true torque. The method according to claim 8, comprising:
The method of calculating the said rotation speed by ratio of a counter electromotive force and a counter electromotive force constant. A method according to any of claims 1 to 9, comprising
When the back electromotive force constant is Ke and the torque constant is Kt,
Ke = Kt
A method of calculating the characteristics of the electric motor using the following formula. A control device for an electric motor,
A resistance value of an electromagnetic coil of the electric motor;
A voltage value of a voltage supplied to the electric motor;
A current value at the time of no load of the electric motor;
The number of rotations of the electric motor when no load is applied;
A characteristic calculation unit for calculating the characteristic of the electric motor based on
A control unit for controlling the electric motor based on the calculated electric motor characteristics;
An electric motor control device. An electric motor,
An electric motor comprising the control device according to claim 11. A method for calculating the true efficiency of an electric motor,
(A) obtaining a back electromotive force generated in the electric motor;
(B) obtaining a voltage value of a voltage supplied to the electric motor;
(C) In the case where the back electromotive force is Eg, the voltage value is Es, and the true efficiency of the motor is ηr,
ηr = 100 × Eg / Es
Calculating the true efficiency ηr of the electric motor according to the equation:
A method comprising: 14. A method according to claim 13, comprising:
In the step (c), when the back electromotive force at no load is Egnl and the true efficiency of the motor at no load is ηrnl,
ηrnl = 100 × Egnl / Es
A method comprising calculating a true efficiency ηrnl of the electric motor at no load according to the formula: A method according to any one of claims 1 to 10, claim 13 and claim 14, comprising:
A method of using a value obtained by multiplying a supply voltage by a duty ratio as an effective voltage value when PWM driving is performed on the electric motor. A method according to any one of claims 1 to 10, and 13 to 15.
When the electromagnetic coil is three-phase star-connected, a resistance value that is twice the resistance value of the electromagnetic coil alone is used as the total resistance of the electromagnetic coil of the electric motor. An apparatus for calculating the characteristics of an electric motor,
A calculation unit that calculates the characteristics of the electric motor based on a true torque that is a torque that the electric motor can theoretically generate;
The true torque is
An external torque that the electric motor generates with respect to an external load;
An apparatus that is a combined torque of an internal torque generated by the electric motor with respect to an internal load. A computer program for causing a computer to execute processing for calculating characteristics of an electric motor,
Based on the true torque that is the torque that the motor can theoretically generate, the function of calculating the characteristics of the motor is realized in the computer,
The true torque is
An external torque that the electric motor generates with respect to an external load;
The computer program which is a torque which combined the internal torque which the said electric motor generate | occur | produces with respect to internal load. An apparatus for calculating the efficiency of an electric motor,
A counter electromotive force acquisition unit for acquiring a counter electromotive force generated in the electric motor;
A supply voltage value acquisition unit for acquiring a voltage value of a voltage supplied to the electric motor;
A calculation unit for calculating the efficiency of the electric motor;
With
In the case where the back electromotive force is Eg, the voltage value is Es, and the efficiency of the motor is ηr,
ηr = 100 × Eg / Es
An apparatus for calculating the efficiency of the electric motor according to the formula: A computer program for causing a computer to execute processing for calculating the efficiency of an electric motor,
(A) a back electromotive force acquisition function for acquiring back electromotive force generated in the electric motor;
(B) a supply voltage value acquisition function for acquiring a voltage value of a voltage supplied to the electric motor;
(C) In the case where the back electromotive force is Eg, the voltage value is Es, and the efficiency of the motor is ηr,
ηr = 100 × Eg / Es
A calculation function for calculating the efficiency ηr of the electric motor according to the equation:
A computer program for causing the computer to realize the above.

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