Current detection device

Abstract

A current detection device for a three-phase motor that can reduce the calculation load in a downstream motor control device that performs vector control. [Solution] Currents flowing through the phase current lines 6u, 6v, 6w of a motor M are detected based on α-phase and β-phase magnetic detection elements Sα, Sβ provided around the three phase current lines 6u, 6v, 6w. If an imaginary plane orthogonal to the three phase current lines 6u, 6v, 6w is defined as an α-phase arrangement plane Pα, and an imaginary plane orthogonal to at least the V-phase and W-phase current lines 6v, 6w and different from the α-phase arrangement plane Pα is defined as a β-phase arrangement plane Pβ, these phase magnetic detection elements Sα, Sβ are provided at positions on the α-phase and β-phase arrangement planes Pα and Pβ, respectively, such that the α-phase layout condition equation and the β-phase layout condition equation, which are determined using a coefficient X other than "-1 / 2," hold.

Description

Technical Field

[0001] The present invention relates to a current detection device. More specifically, the present invention relates to a current detection device that detects the current of each phase of a three-phase motor based on two magnetic detection elements.

Background Art

[0002] In recent years, efforts to achieve a low-carbon society or a decarbonized society have been active, and research and development on electric vehicles have been conducted in vehicles as well in order to reduce CO2 emissions and improve energy efficiency.

[0003] As a control method for three-phase AC motors mounted on electric vehicles, home electric appliances (for example, air conditioners, washing machines, etc.), so-called vector control is widely adopted. In vector control, a motor control device generates a command signal for an inverter based on feedback control of a d-axis current and a q-axis current defined on a d-q coordinate system, which is a rotating orthogonal coordinate system of the motor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Thus, in the motor control device, in order to perform feedback control of current on the d-q coordinate system, for example, it is necessary to convert the U-phase current, V-phase current, and W-phase current of the motor detected using a current detection device as shown in Patent Document 1 into d-axis current and q-axis current. More specifically, in the motor control device, first, the three-phase current (Iu, Iv, Iw) detected by the current detection device is converted into a two-phase current (Iα, Iβ) defined in the fixed coordinate system by Clark transformation, and then this two-phase current (Iα, Iβ) is converted into a two-phase current (Id, Iq) defined in the d-q coordinate system by Park transformation using the rotation angle θ of the motor. In this way, in the vector control using the output of the conventional current detection device, it is necessary to execute an operation for converting the three-phase current (Iu, Iv, Iw) into the two-phase current (Id, Iq) in the motor control device.

[0006] Also, in Patent Document 2 by the applicant of the present application, there is described a technique (hereinafter, such a technique is also referred to as "spatial Clark transformation") for directly obtaining the two-phase current (Iα, Iβ) without going through the Clark transformation by computer calculation by providing two magnetic detection elements at geometrically determined positions around three phase current lines. According to such spatial Clark transformation, it is possible to reduce the number of magnetic detection elements and also reduce the computational load of the computer compared with the conventional case.

[0007] However, in the spatial Clark transformation shown in Patent Document 2, the layout of the three phase current lines and the two magnetic detection elements is limited to about several patterns. Since it is necessary to efficiently arrange various components in an electric vehicle, it is preferable that the degree of freedom in the layout of the phase current lines and the magnetic detection elements is as high as possible.

[0008] An object of the present invention is to provide a current detection device for a three-phase motor that can reduce the computational load in a subsequent-stage motor control device that performs vector control, and ultimately contribute to the improvement of energy efficiency.

Means for Solving the Problems

[0009] (1) A current detection device (for example, a current detection device 3 described later) according to the present invention detects currents flowing through a first current line (for example, a U-phase current line 6u described later), a second phase current line (for example, a V-phase current line 6v described later), and a third phase current line (for example, a W-phase current line 6w described later) of a three-phase motor (for example, a motor M described later) based on an α-phase magnetic detection element (for example, an α-phase magnetic detection element Sα described later) and a β-phase magnetic detection element (for example, a β-phase magnetic detection element Sβ described later) provided around the first, second, and third phase current lines, and the current value flowing through the first phase current line is I1, the current value flowing through the second phase current line is I2, and When the current value flowing through the third-phase current line is I3, the output value of the α-phase magnetic detection element is Vα, the output value of the β-phase magnetic detection element is Vβ, an imaginary plane perpendicular to the first, second, and third-phase current lines is an α-phase arrangement plane (for example, the α-phase arrangement plane Pα described below), and an imaginary plane perpendicular to at least the second and third-phase current lines and different from the α-phase arrangement plane is a β-phase arrangement plane (for example, the β-phase arrangement plane Pβ described below), the α-phase and β-phase magnetic detection elements are disposed at positions within the α-phase and β-phase arrangement planes, respectively, such that the following equations (1-1) and (1-2), which are determined using a coefficient X other than "-1 / 2", hold.

number

[0010] (2) In this case, it is preferable that the α-phase magnetic detection element is arranged on a virtual α-phase arrangement line (e.g., α-phase arrangement line Lα described later) that is perpendicular to an α-phase line segment (e.g., α-phase line L1 described later) connecting the second phase current line and the third phase current line within the α-phase arrangement plane and bisects the α-phase line segment.

[0011] (3) In this case, it is preferable that the first phase current line intersects the α phase layout plane at a point where the α phase line segment and the α phase layout line intersect, and the direction of the DC current flowing through the first, second, and third phase current lines from the power source toward the three-phase motor is the same on the α phase layout plane.

[0012] (4) In this case, it is preferable that the first phase current line intersects the α phase arrangement plane at a point other than the α phase arrangement line (for example, points P1, P2, P3, and P4 described below).

[0013] (5) In this case, it is preferable that the β-phase magnetic detection element is arranged on a virtual β-phase arrangement line (e.g., β-phase arrangement line Lβ described below) that is perpendicular to a β-phase line segment (e.g., β-phase line segment L2 described below) connecting the second phase current line and the third phase current line within the β-phase arrangement plane and bisects the β-phase line segment.

[0014] (6) In this case, it is preferable that the distance along the beta phase arrangement surface between the beta phase magnetic detection element and the first phase current line is longer than the distance along the beta phase arrangement surface between the beta phase magnetic detection element and the second or third phase current line.

[0015] (7) In this case, it is preferable that the detection axis of the β-phase magnetic detection element (for example, a detection axis Oβ described later) is perpendicular to the magnetic flux formed in the β-phase arrangement plane by the current flowing through the first phase current line.

[0016] (8) In this case, it is preferable to further provide a calculation means (e.g., a current correction calculation unit 22 described below) that multiplies the output value of the β-phase magnetic detection element by a β-phase gain (e.g., a β-phase gain Gβ described below) and outputs the result as a β-phase current value (e.g., a β-phase current value Iβ described below), and multiplies the output value of the α-phase magnetic detection element by an α-phase gain (e.g., an α-phase gain Gα described below) that has a value different from the β-phase gain and outputs the result as an α-phase current value (e.g., an α-phase current value Iα described below).

[0017] (9) In this case, it is preferable that the values of the α-phase and β-phase gains are set so that the amplitudes of the α-phase and β-phase current values are equal to each other. [Effects of the Invention]

[0018] (1) In the current detection device according to the present invention, the currents flowing through the three current lines are detected based on two magnetic detection elements provided around these current lines. Therefore, according to the present invention, the number of magnetic detection elements can be reduced compared to the conventional current detection device in which one magnetic detection element is provided for each current line, and thus the cost can be reduced accordingly. In the current detection device according to the present invention, the α-phase and β-phase magnetic detection elements are provided at positions where the above formulas (1-1) and (1-2) defined using a coefficient X other than "-1 / 2" are satisfied. On the other hand, in the space Clarke transformation described in the Chinese patent application CN202211040361.X (hereinafter also simply referred to as the "prior application") by the applicant of the present application, the relative positions and the directions of the detection axes of the α-phase and β-phase magnetic detection elements with respect to the first-phase to third-phase current lines are determined such that a matrix arithmetic formula equivalent to the Clarke transformation (that is, corresponding to the case where X = 1 in the above formulas (1-1) and (1-2)) is satisfied. Therefore, according to the present invention, the above formulas (1-1) and (1-2) can increase the degree of freedom in the layout of the three-phase current lines and the two magnetic detection elements compared to the conventional space Clarke transformation by including an arbitrary coefficient X.

[0019] Also, as will be described in detail later, the currents obtained by multiplying the three-phase currents (I1, I2, I3) with different phases by 2π / 3 by the transformation matrix (X, -1 / 2, -1 / 2) described in the above formula (1-1) have the same phase as the currents obtained by multiplying the three-phase currents (I1, I2, I3) by the first row component (1, -1 / 2, -1 / 2) of the transformation matrix of the Clarke transformation, except for the amplitude. This means that the output value Vα of the α-phase magnetic detection element provided so that the above formula (1-1) is satisfied can be made equal to the output value of the magnetic detection element described in the prior application by multiplying by a predetermined gain. Therefore, according to the current detection device of the present invention, by using the output values of the two magnetic detection elements, in the motor control device provided in the subsequent stage, it is not necessary to perform the Clarke transformation by calculation, and thus the calculation load of the motor control device can be reduced accordingly, and as a result, it can contribute to the improvement of energy efficiency.

[0020] Incidentally, as shown in the above formula (1-2), the β-phase magnetic detection element needs to be provided at a position that is not affected by the current flowing through the first-phase current line. Therefore, when the α-phase and β-phase magnetic detection elements are arranged in the same arrangement plane orthogonal to the three-phase current lines so that the above formulas (1-1) and (1-2) are satisfied, the place where the β-phase magnetic detection element can be arranged is limited. Therefore, in the present invention, the α-phase magnetic detection element is arranged in an α-phase arrangement plane orthogonal to the first, second, and third-phase current lines, and the β-phase magnetic detection element is arranged in a β-phase arrangement plane that is orthogonal to at least the second and third-phase current lines and different from the α-phase arrangement plane. Therefore, according to the present invention, compared with the case where the two magnetic detection elements are arranged in a common arrangement plane, the degree of freedom of the arrangement layout of the three-phase current lines and the two magnetic detection elements can be further improved.

[0021] (2) In the present invention, by arranging the α-phase magnetic detection element on a virtual α-phase arrangement line that is orthogonal to and bisects the α-phase line segment connecting the second and third-phase current lines in the α-phase arrangement plane, the α-phase magnetic detection element can be arranged at a free position according to requirements while satisfying the above formula (1-1).

[0022] (3) In the present invention, by arranging the first, second, and third-phase current lines side by side in the α-phase arrangement plane, the three-phase current lines can be compactly grouped together while satisfying the above formula (1-1). Although the three-phase current lines can also be arranged side by side in the space Clarke transformation described in the previous application, since the direction of the phase current line arranged in the center needs to be opposite to the other two (see FIGS. 4 and 5 of the previous application), the phase current lines need to be twisted. In contrast, according to the present invention, the three-phase current lines can be arranged side by side without twisting the phase current lines.

[0023] (4) In the present invention, by providing the first-phase current line at a position orthogonal to the α-phase arrangement plane at a point other than the α-phase arrangement line, the first-phase current line can be arranged at a free position while satisfying the above formula (1-1).

[0024] (5) In the present invention, by arranging the β-phase magnetic detection element on a virtual β-phase arrangement line that is orthogonal to the β-phase line segment connecting the second and third phase current lines in the β-phase arrangement plane and bisects this β-phase line segment, the β-phase magnetic detection element can be arranged at a free position according to requirements while satisfying the above formula (1-2).

[0025] (6) In the present invention, in the β-phase arrangement plane, by providing the β-phase magnetic detection element at a position where the first phase current line is farther than the second or third phase current line, the first phase current line can be arranged at a free position according to requirements while satisfying the above formula (1-2).

[0026] (7) In the present invention, by arranging the β-phase magnetic detection element such that the detection axis of the β-phase magnetic detection element is orthogonal to the magnetic flux formed in the β-phase arrangement plane by the current flowing through the first phase current line, the β-phase magnetic detection element can be arranged at a free position according to requirements while satisfying the above formula (1-2).

[0027] (8) In the present invention, the arithmetic means calculates the α-phase and β-phase current values by multiplying the output values of the α-phase and β-phase magnetic detection elements by the α-phase and β-phase gains respectively. Therefore, in the present invention, the difference in amplitude of the output values of the two magnetic detection elements caused by the coefficient X included in the above formula (1-1) can be eliminated by the calculation in the arithmetic means. Therefore, according to the present invention, the α-phase and β-phase current values can be obtained without performing the Clark transformation calculation.

[0028] (9) In the present invention, by setting the values of the α-phase and β-phase gains such that the amplitudes of the α-phase and β-phase current values are equal, the α-phase and β-phase current values can be obtained without performing the Clark transformation calculation.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiment for Carrying Out the Invention

[0030] Hereinafter, a current detection device according to an embodiment of the present invention and an electric vehicle equipped with this current detection device will be described with reference to the drawings.

[0031] FIG. 1 is a diagram showing the configuration of a current detection device 3 according to the present embodiment and an electric vehicle V equipped with this current detection device. Hereinafter, the case where the current detection device 3 is mounted on the electric vehicle V will be described, but the present invention is not limited thereto. The current detection device 3 can be mounted on any device that controls a three-phase motor based on vector control, such as an air conditioner or a washing machine, in addition to the electric vehicle V.

[0032] The electric vehicle V includes a three-phase AC motor M (hereinafter simply referred to as "motor M"), drive wheels W connected to the output shaft of this motor M via a power transmission mechanism (not shown), an inverter 1 that connects a battery (not shown) and the motor M, a sensor unit S that generates a signal corresponding to the current flowing through the motor M, a resolver 4 that detects the rotational position of the motor M, and a motor control device 2 that controls the inverter 1 based on the detection signals of these sensor unit S and resolver 4.

[0033] The inverter 1 is, for example, a PWM inverter by pulse width modulation, which includes a bridge circuit configured by connecting a plurality of switching elements (for example, IGBTs) in a bridge connection, and has a function of converting DC power and AC power. The inverter 1 is connected to the battery on its DC input / output side, and is connected to the coils of the U-phase, V-phase, and W-phase of the motor M on its AC input / output side, and converts power between the battery and the motor M. The inverter 1 drives each phase of the switching element to be turned on / off according to a gate drive signal generated at a predetermined timing from a gate drive circuit (not shown), thereby converting the DC power supplied from the battery into AC power and supplying it to the motor M, or converting the AC power supplied from the motor M into DC power and supplying it to the battery.

[0034] The sensor unit S includes an α-phase magnetic detection element Sα and a β-phase magnetic detection element Sβ provided around three phase current lines (U-phase current line 6u, V-phase current line 6v, and W-phase current line 6w) connecting the motor M and the inverter 1. These magnetic detection elements Sα and Sβ generate detection signals corresponding to the components along the respective detection axes of the magnetic flux density of the magnetic field generated by the currents flowing through the respective phase current lines 6u, 6v, and 6w. Specific examples of the layout of these α-phase and β-phase magnetic detection elements Sα and Sβ and the three phase current lines 6u, 6v, and 6w will be described later with reference to FIGS. 2 to 5.

[0035] The motor control device 2 is a computer that generates a drive signal for the gate drive circuit of the inverter 1 by performing vector control based on the detection signals from the two magnetic detection elements Sα and Sβ and the resolver 4, and inputs it to this gate drive circuit.

[0036] The motor control device 2 includes an AD conversion unit 21, a current correction calculation unit 22, a dq conversion unit 23, and a duty calculation unit 24 as modules related to the execution of the above-described vector control.

[0037] The AD conversion unit 21 obtains the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα, Sβ by performing AD conversion on the detection signals of the α-phase and β-phase magnetic detection elements Sα, Sβ.

[0038] As shown in the following formula (2), the current correction calculation unit 22 outputs the values obtained by multiplying the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα, Sβ respectively, which are obtained by the AD conversion unit 21, by the α-phase gain Gα and the β-phase gain Gβ, as the α-phase current value Iα and the β-phase current value Iβ. Note that the values of these α-phase and β-phase gains (Gα, Gβ) are set so that the amplitudes of the α-phase and β-phase current values (Iα, Iβ) are equal.

Equation

[0039] As described below, the α-phase and β-phase current values (Iα, Iβ) calculated by the current correction calculation unit 22 are proportional to the two-phase current (Iα_ideal, Iβ_ideal) obtained by multiplying the three-phase current (Iu, Iv, Iw) of the motor M by the 2×3 Clarke transformation matrix shown in the following formula (3). In the following, the current value flowing through the U-phase current line 6u is denoted as Iu, the current value flowing through the V-phase current line 6v is denoted as Iv, and the current value flowing through the W-phase current line 6w is denoted as Iw. Therefore, in the motor control device 2, in the dq conversion unit 23 described later, when calculating the two-phase current (Id, Iq) in the d-q coordinate system, it is not necessary to perform the operation using the Clarke transformation matrix shown in the following formula (3), so the operation load in the motor control device 2 can be reduced compared with the conventional case. Therefore, in the present embodiment, the current detection device 3 for detecting the current flowing through the three-phase current lines 6u, 6v, 6w of the motor M is composed of two magnetic detection elements Sα, Sβ, an AD conversion unit 21, and a current correction calculation unit 22.

Equation

[0040] The dq conversion unit 23 performs a known calculation using the output values (Iα, Iβ) of the current correction calculation unit 22 and the detection signal of the resolver 4 to calculate the d-axis current Id and the q-axis current Iq.

[0041] The duty calculation unit 24 acquires the d-axis current command Idc and the q-axis current command Iqc according to the driving force required by the driver, and performs feedback control based on the deviation of these current values (Idc-Id, Iqc-Iq) to generate a driving signal for the gate drive circuit of the inverter 1 so as to realize the driving force required by the driver, and inputs the signal to the gate drive circuit.

[0042] Next, a description will be given of the conditions imposed on the layout of the three phase current lines 6u, 6v, and 6w and the two magnetic detection elements Sα and Sβ in order to establish the above formula (3).

[0043] First, as described above, the current correction calculation unit 22 calculates the α-phase and β-phase current values (Iα, Iβ) so that their amplitudes are equal by multiplying the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα and Sβ by the α-phase and β-phase gains (Gα, Gβ). Therefore, the phase difference between the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα and Sβ must be equal to the phase difference between the two-phase currents (Iα_ideal, Iβ_ideal) obtained by the above equation (3). However, the amplitudes of these output values (Vα, Vβ) may be different. In other words, the difference in amplitude between these output values (Vα, Vβ) can be eliminated by adjusting the values of the α-phase and β-phase gains (Gα, Gβ) in the current correction calculation unit 22. Therefore, if the three phase current lines 6u, 6v, 6w and the two magnetic detection elements Sα, Sβ are arranged so that the following equations (4-1) and (4-2), which are imposed separately on the two output values (Vα, Vβ), hold, the above equation (3) can be established.

number

[0044] Also, as will be described later, assuming that there is a phase difference of 2π / 3 between the current values (Iu, Iv, Iw) flowing through each of the phase current lines 6u, 6v, and 6w, the above equations (4-1) and (4-2) can be generalized as the following equations (5-1) and (5-2) using an arbitrary coefficient X. Therefore, in the present embodiment, the layout of the three phase current lines 6u, 6v, 6w and the two magnetic detection elements Sα, Sβ (that is, the layout of the three phase current lines 6u, 6v, 6w and the relative positions of the two magnetic detection elements Sα, Sβ with respect to these phase current lines 6u, 6v, 6w and the directions of the detection axes) is determined such that the following equations (5-1) and (5-2) using a coefficient X other than "-1" are satisfied. Note that in the layout where the value of the coefficient X in the following equation (5-1) is "-1 / 2", theoretically, the output value of the magnetic detection element Sα is constantly "0". Therefore, in the following equation (5-1), the layout where the value of the coefficient X is "-1 / 2" is excluded.

Equation

[0045] Next, the reason why the above equation (4-1) can be generalized to the above equation (5-1) will be explained. First, the output value Vα´ of the α-phase magnetic detection element Sα when the α-phase magnetic detection element Sα and the three phase current lines 6u, 6v, 6w are arranged at arbitrary positions is expressed by the following equation (6) using arbitrary coefficients (X, A, B). Here, the values of the coefficients (X, A, B) change according to the relative positions of the α-phase magnetic detection element Sα with respect to the three phase current lines 6u, 6v, 6w and the direction of the detection axis. More specifically, the value of the coefficient X is determined according to the relative position of the α-phase magnetic detection element Sα with respect to the U-phase current line 6u and the direction of the detection axis, the value of the coefficient A is determined according to the relative position of the α-phase magnetic detection element Sα with respect to the V-phase current line 6v and the direction of the detection axis, and the value of the coefficient B is determined according to the relative position of the α-phase magnetic detection element Sα with respect to the W-phase current line 6w and the direction of the detection axis.

Equation

[0046] Also, assuming that there is a phase difference of 2π / 3 between the current values (Iu, Iv, Iw) flowing through the respective phase current lines 6u, 6v, and 6w with respect to the U phase, the following formula (7) is derived from the above formula (6) by the addition theorem. In the following formula (7), Iu = sinθ, Iv = sin(θ - 2π / 3), and Iw = sin(θ + 2π / 3).

Number

[0047] Here, in the above formula (7), assuming A = B in the same manner as in the above formula (4-1), the following formula (8) is derived. The assumption of A = B corresponds to making the distance between the V-phase current line 6v and the α-phase magnetic detection element Sα equal to the distance between the W-phase current line 6w and the α-phase magnetic detection element Sα, and arranging the phase current lines 6v, 6w, and the α-phase magnetic detection element Sα at a position where the angle formed by the line segment connecting the V-phase current line 6v and the α-phase magnetic detection element Sα and the detection axis of the α-phase magnetic detection element Sα is equal to the angle formed by the line segment connecting the W-phase current line 6w and the α-phase magnetic detection element Sα and the detection axis of the α-phase magnetic detection element Sα.

Number

[0048] As shown in the formula (8), assuming A = B, the term of cosθ disappears from the above formula (7), and the output value Vα´ of the α-phase magnetic detection element Sα is proportional only to sinθ. That is to say, within the range where A = B, no matter how the relative position of the α-phase magnetic detection element Sα with respect to the U-phase current line 6u and the direction of the detection axis change (that is, no matter how the value of X changes), the phase of the output value Vα´ does not change. In other words, within the range where A = B, no matter how the relative position of the α-phase magnetic detection element Sα with respect to the U-phase current line 6u and the direction of the detection axis change (that is, no matter how the value of X changes), only the amplitude of the output value Vα´ changes. As shown in the above formula (8), when the α-phase magnetic detection element Sα is arranged at the position where the values of all coefficients are equal (that is, the position where X = A = B), the output value Vα´ constantly becomes "0". For the above reasons, the above formula (4-1) can be generalized as shown in the above formula (5-1) using an arbitrary coefficient X except "-1 / 2".

[0049] Next, the layout of the three-phase current lines 6u, 6v, 6w and the two magnetic detection elements Sα, Sβ that satisfy the above formulas (5-1) and (5-2) will be described. Hereinafter, the above formula (5-1) imposed on the output value Vα of the α-phase magnetic detection element Sα is referred to as the α-phase layout conditional formula, and the above formula (5-2) imposed on the output value Vβ of the β-phase magnetic detection element Sβ is referred to as the β-phase layout conditional formula.

[0050] Figure 2 is a side view of the three-phase current lines 6u, 6v, 6w, and the α-phase arrangement plane Pα and the β-phase arrangement plane Pβ orthogonal to these phase current lines. Hereinafter, as shown in Figure 2, the case where the α-phase magnetic detection element Sα is provided in a virtual α-phase arrangement plane Pα orthogonal to the three-phase current lines 6u, 6v, 6w, and the β-phase magnetic detection element Sβ is provided in a β-phase arrangement plane Pβ orthogonal to at least two phase current lines 6v, 6w and different from the α-phase arrangement plane Pα will be described, but the present invention is not limited thereto. These two magnetic detection elements Sα, Sβ may both be provided in the same α-phase arrangement plane Pα.

[0051] FIG. 3 is a diagram schematically illustrating an α-phase arrangement plane Pα on which the α-phase magnetic detection element Sα is provided. More specifically, FIG. 3 is a diagram illustrating an arrangement range of the α-phase magnetic detection element Sα within the α-phase arrangement plane Pα that satisfies the α-phase layout conditional expression (5-1). Note that FIG. 3 illustrates a case in which the three phase current wires 6u, 6v, and 6w are arranged at equal intervals within the α-phase arrangement plane Pα in the order of the V-phase current wire 6v, the U-phase current wire 6u, and the W-phase current wire 6w. However, the present invention is not limited to this. Also, FIG. 3 illustrates a case in which the DC currents flowing through the phase current wires 6u, 6v, and 6w from the inverter 1, which serves as the power source, toward the motor M are aligned in the same direction within the α-phase arrangement plane Pα. However, the present invention is not limited to this.

[0052] First, to satisfy the α-phase layout condition formula (5-1), the α-phase magnetic detection element Sα must be arranged on an imaginary α-phase arrangement line Lα that is perpendicular to an imaginary α-phase line L1 connecting the V-phase current line 6v and the W-phase current line 6w within the α-phase arrangement plane Pα and that bisects this α-phase line L1. In other words, the α-phase magnetic detection element Sα must be arranged at a position (i.e., on the α-phase arrangement line Lα) such that the distance between the V-phase current line 6v and the W-phase current line 6w within the α-phase arrangement plane Pα is equal.

[0053] Furthermore, to satisfy the α-phase layout condition formula (5-1), the detection axis Oα of the α-phase magnetic detection element Sα must be perpendicular to the α-phase layout line Lα within the α-phase layout plane Pα, as shown in Figure 3. However, in this case, if the α-phase magnetic detection element Sα is placed at the intersection of the α-phase line segment L1 and the α-phase layout line Lα, the detection axis Oα will be perpendicular to the magnetic flux formed by the phase current lines 6v and 6w. For this reason, the α-phase magnetic detection element Sα must be placed at a position on the α-phase layout line Lα other than the intersection with the α-phase line segment L1.

[0054] Also, as described above, the α-phase layout conditional expression (5-1) includes an arbitrary coefficient X. Therefore, the U-phase current line 6u may be provided at any position within the α-phase layout plane Pα except for the dead point P0 where the value of the coefficient X is "-1 / 2". That is, the U-phase current line 6u within the α-phase layout plane Pα is not limited to the midpoint of the α-phase line segment L1 as shown in FIG. 3. For example, as shown at points P1, P2, P3, P4, etc., the α-phase layout conditional expression (5-1) is satisfied even if it is provided at a position orthogonal to a point other than the α-phase layout line Lα with respect to the α-phase layout plane Pα. Here, the dead point P0 is the arrangement position of the U-phase current line 6u such that the output value Vα of the α-phase magnetic detection element Sα becomes constantly "0" as described above. When the α-phase magnetic detection element Sα and the v-phase and w-phase current lines 6v, 6w are provided at the positions as shown in FIG. 3, the dead point P0 appears on the α-phase layout line Lα as shown in FIG. 3.

[0055] FIG. 4 is a diagram showing another example of the arrangement range of the α-phase magnetic detection element Sα that satisfies the α-phase layout conditional expression (5-1) within the α-phase layout plane Pα. Note that FIG. 4 shows a case where each phase current line 6u, 6v, 6w is arranged at the corner of an isosceles triangle with the U-phase current line 6u as the apex angle, which is different from the example of FIG. 3.

[0056] As shown in FIG. 4, even when the three phase current lines 6u, 6v, 6w are arranged at the corners of an isosceles triangle within the α-phase layout plane Pα, the α-phase magnetic detection element Sα can satisfy the α-phase layout conditional expression (5-1) by being arranged on the α-phase layout line Lα such that the detection axis Oα is orthogonal to the α-phase layout line Lα.

[0057] FIG. 5 is a diagram schematically showing the β-phase layout plane Pβ where the β-phase magnetic detection element Sβ is provided. More specifically, FIG. 5 is a diagram for explaining the arrangement range of the β-phase magnetic detection element Sβ that satisfies the β-phase layout conditional expression (5-2) within the β-phase layout plane Pβ. Also, FIG. 5 shows a case where in the β-phase layout plane Pβ, the directions of the direct current flowing through each phase current lines 6v, 6w from the inverter 1, which is the power source, to the motor M are the same, but the present invention is not limited to this.

[0058] First, in order to satisfy the β-phase layout conditional expression (5-2), the β-phase magnetic detection element Sβ needs to be arranged on a virtual β-phase layout line Lβ that is orthogonal to a virtual β-phase line segment L2 connecting the V-phase current line 6v and the W-phase current line 6w within the β-phase layout plane Pβ and bisects this β-phase line segment L2. That is, the β-phase magnetic detection element Sβ needs to be arranged at a position (i.e., on the above β-phase layout line Lβ) where the distances in the β-phase layout plane Pβ are equal between the V-phase current line 6v and the W-phase current line 6w.

[0059] Also, in order to satisfy the β-phase layout conditional expression (5-2), the detection axis Oβ of the β-phase magnetic detection element Sβ needs to be parallel to the β-phase layout line Lβ within the β-phase layout plane Pβ as illustrated in FIG. 5.

[0060] Also, in order to satisfy the β-phase layout conditional expression (5-2), the β-phase magnetic detection element Sβ needs to be provided at a position where it is not affected by the magnetic flux formed in the β-phase layout plane Pβ by the current flowing through the U-phase current line 6u (not shown). This can be achieved, for example, by making the distance along the β-phase layout plane Pβ between the β-phase magnetic detection element Sβ and the U-phase current line 6u (not shown) sufficiently longer than the distance along the β-phase layout plane Pβ between the β-phase magnetic detection element Sβ and the V-phase current line 6v or the W-phase current line 6w. Also, when the U-phase current line 6u is arranged to be orthogonal to the β-phase layout plane Pβ at the intersection point P5 of the β-phase line segment L2 and the β-phase layout line Lβ, it can also be achieved by arranging the detection axis Oβ of the β-phase magnetic detection element Sβ parallel to the β-phase layout line Lβ and making it orthogonal to the magnetic flux formed in the β-phase layout plane Pβ by the current flowing through the U-phase current line 6u.

[0061] Furthermore, to satisfy the β-phase layout condition formula (5-2), the detection axis Oβ of the β-phase magnetic detection element Sβ must be perpendicular to the magnetic flux formed by the current flowing through the U-phase current line 6u. Therefore, when the three phase current lines 6u, 6v, and 6w are arranged at equal intervals as shown in Figure 3, in order to satisfy the β-phase layout condition formula (5-2), the detection axis Oβ of the β-phase magnetic detection element Sβ must be parallel to the α-phase layout line Lα within the layout plane P, as shown in the example of Figure 3. Therefore, by arranging the β-phase magnetic detection element Sβ on the α-phase layout line Lα so that its detection axis Oβ is parallel to the α-phase layout line Lα, the β-phase layout condition formula (5-2) can be satisfied.

[0062] The current detecting device 3 according to this embodiment has the following advantages. (1) The current detection device 3 detects the currents flowing through the three phase current lines 6u, 6v, and 6w based on two magnetic detection elements Sα and Sβ arranged around these phase current lines 6u, 6v, and 6w. Therefore, the current detection device 3 can reduce the number of magnetic detection elements compared to conventional current detection devices that provide one magnetic detection element for each current line, thereby reducing costs. Furthermore, in the current detection device 3, the α-phase magnetic detection element Sα and the β-phase magnetic detection element Sβ are arranged in positions within the α-phase layout plane Pα and the β-phase layout plane Pβ, respectively, such that the α-phase layout condition formula (5-1) and the β-phase layout condition formula (5-2), which are determined using a coefficient X other than "-1 / 2," are satisfied. Therefore, according to the current detection device 3, the above equations (5-1) and (5-2) include an arbitrary coefficient X, which allows for a higher degree of freedom in the layout of the three phase current lines 6u, 6v, and 6w and the two magnetic detection elements Sα and Sβ than the spatial Clarke transformation described in the previous application by the applicant of the present application.

[0063] Also, as described above, the current obtained by multiplying the three-phase currents (Iu, Iv, Iw) with different phases by 2π / 3 by the transformation matrix (X, -1 / 2, -1 / 2) described in the α-phase layout conditional expression (5-1) has the same phase as the current obtained by multiplying the three-phase currents (Iu, Iv, Iw) by the first row component (1, -1 / 2, -1 / 2) of the transformation matrix of the Clarke transformation, and only differs in amplitude. This means that the output value Vα of the α-phase magnetic detection element Sα provided so that the α-phase layout conditional expression (5-1) holds can be made equal to the output value of the first magnetic detection element described in the prior application by multiplying by a predetermined gain. Therefore, according to the current detection device 3, by using the output values (Vα, Vβ) of the two magnetic detection elements Sα and Sβ, in the motor control device 2 provided in the subsequent stage, it is not necessary to perform the Clarke transformation by calculation, so the calculation load of the motor control device 2 can be reduced accordingly, and thus it can contribute to the improvement of energy efficiency.

[0064] By the way, as shown in the β-phase layout conditional expression (5-2), the β-phase magnetic detection element Sβ needs to be provided at a position where it is not affected by the current flowing through the U-phase current line 6u. For this reason, when the α-phase and β-phase magnetic detection elements Sα and Sβ are arranged in the same α-phase arrangement plane Pα orthogonal to the three-phase current lines 6u, 6v, and 6w so that the α-phase layout conditional expression (5-1) and the β-phase layout conditional expression (5-2) are satisfied, the location where the β-phase magnetic detection element Sβ can be arranged is restricted. Therefore, in the current detection device 3, the α-phase magnetic detection element Sα is arranged in the α-phase arrangement plane Pα orthogonal to the three-phase current lines 6u, 6v, and 6w, and the β-phase magnetic detection element Sβ is arranged in a β-phase arrangement plane Pβ that is orthogonal to at least the V-phase and W-phase current lines 6v and 6w and is different from the α-phase arrangement plane Pα. Therefore, according to the current detection device 3, compared with the case where the two magnetic detection elements Sα and Sβ are arranged in the common α-phase arrangement plane Pα, the degree of freedom of the layout of the three-phase current lines 6u, 6v, 6w and the two magnetic detection elements Sα and Sβ can be further improved.

[0065] (2) In the current detection device 3, the α-phase magnetic detection element Sα is arranged on a virtual α-phase arrangement line Lα that is orthogonal to and bisects the α-phase line segment L1 connecting the V-phase and W-phase current lines 6v and 6w within the α-phase arrangement plane Pα. By doing so, the α-phase magnetic detection element Sα can be arranged at a free position according to requirements while satisfying the α-phase layout conditional expression (5-1).

[0066] (3) In the current detection device 3, within the α-phase arrangement plane Pα, by arranging the three-phase current lines 6u, 6v, and 6w side by side, the three-phase current lines 6u, 6v, and 6w can be compactly grouped together while satisfying the α-phase layout conditional expression (5-1). In the space Clarke transformation described in the previous application, although the three-phase current lines 6u, 6v, and 6w can be arranged side by side, it is necessary to reverse the direction of the U-phase current line 6u arranged in the center compared to the other two (see FIGS. 4 and 5 of the previous application), so it is necessary to twist the U-phase current line 6u. In contrast, according to the current detection device 3, the three-phase current lines 6u, 6v, and 6w can be arranged side by side without twisting the phase current lines.

[0067] (4) In the current detection device 3, the U-phase current line 6u is provided at a position orthogonal to the α-phase arrangement plane Pα at a point other than the α-phase arrangement line Lα. By doing so, the U-phase current line 6u can be arranged at a free position while satisfying the α-phase layout conditional expression (5-1).

[0068] (5) In the current detection device 3, the β-phase magnetic detection element Sβ is arranged on a virtual β-phase arrangement line Lβ that is orthogonal to and bisects the β-phase line segment L2 connecting the V-phase and W-phase current lines 6v and 6w within the β-phase arrangement plane Pβ. By doing so, the β-phase magnetic detection element Sβ can be arranged at a free position according to requirements while satisfying the β-phase layout conditional expression (5-2).

[0069] (6) In the current detection device 3, in the β-phase arrangement plane Pβ, the β-phase magnetic detection element Sβ is provided at a position where the U-phase current line 6u is farther from the V-phase or W-phase current lines 6v, 6w than the U-phase current line 6u, so that the U-phase current line 6u can be arranged at a free position according to the requirement while satisfying the β-phase layout conditional expression (5-2).

[0070] (7) In the current detection device 3, the β-phase magnetic detection element Sβ is arranged such that the detection axis Oβ of the β-phase magnetic detection element Sβ is orthogonal to the magnetic flux formed in the β-phase arrangement plane Pβ by the current flowing through the U-phase current line 6u, so that the β-phase magnetic detection element Sβ can be arranged at a free position according to the requirement while satisfying the β-phase layout conditional expression (5-2).

[0071] (8) In the current detection device 3, the current correction calculation unit 22 calculates the α-phase and β-phase current values (Iα, Iβ) by multiplying the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα, Sβ by the α-phase and β-phase gains (Gα, Gβ), respectively. Therefore, in the current detection device 3, the difference in amplitude between the output values (Vα, Vβ) of the two magnetic detection elements Sα, Sβ caused by the coefficient X included in the α-phase layout conditional expression (5-1) can be eliminated by the calculation in the current correction calculation unit 22. Therefore, according to the current detection device 3, the α-phase and β-phase current values can be obtained without performing the Clark transformation operation.

[0072] (9) In the current detection device 3, the α-phase and β-phase current values (Iα, Iβ) can be obtained without performing the Clark transformation operation by setting the values of the α-phase and β-phase gains (Gα, Gβ) such that the amplitudes of the α-phase and β-phase current values (Iα, Iβ) are equal.

[0073] As described above, an embodiment of the present invention has been described, but the present invention is not limited thereto. Within the scope of the gist of the present invention, the detailed configuration may be appropriately changed.

Explanation of Reference Numerals

[0074] V... Vehicle W... Driving Wheel M... Motor (Three-Phase Motor) 6u… U-phase current line (first-phase current line) 6v… V-phase current line (second-phase current line) 6w… W-phase current line (third-phase current line) 1… Inverter (power source) 2… Motor control device 21… AD conversion unit 22… Current correction calculation unit (calculation means) 23… dq conversion unit 24… Duty calculation unit 3… Current detection device Sα… α-phase magnetic detection element Oα… Detection axis Pα… α-phase arrangement plane L1… α-phase line segment Lα… α-phase arrangement line Sβ… β-phase magnetic detection element Oβ… Detection axis Pβ… β-phase arrangement plane L2… β-phase line segment Lβ… β-phase arrangement line 4… Resolver

Claims

1. A current detection device that detects currents flowing through a first-phase current line, a second-phase current line, and a third-phase current line of a three-phase motor based on an α-phase magnetic detection element and a β-phase magnetic detection element provided around the first-phase, second-phase, and third-phase current lines, wherein a current value flowing through the first-phase current line is I1, a current value flowing through the second-phase current line is I2, a current value flowing through the third-phase current line is I3, an output value of the α-phase magnetic detection element is Vα, an output value of the β-phase magnetic detection element is Vβ, a virtual plane orthogonal to the first, second, and third-phase current lines is defined as an α-phase arrangement plane, and a virtual plane that is orthogonal to at least the second and third-phase current lines and is different from the α-phase arrangement plane is defined as a β-phase arrangement plane. In this case, the α-phase and β-phase magnetic detection elements are provided at positions where the following formulas (1-1) and (1-2) defined using a coefficient X other than "-1 / 2" are satisfied within the α-phase and β-phase arrangement planes, respectively. A current detection device characterized by this. 【Number 1】

2. The current detection device according to claim 1, wherein the α-phase magnetic detection element is arranged on a virtual α-phase arrangement line that is orthogonal to and bisects an α-phase line segment connecting the second-phase current line and the third-phase current line within the α-phase arrangement plane.

3. The first-phase current line is orthogonal to the α-phase arrangement plane at the intersection of the α-phase line segment and the α-phase arrangement line, The current detection device according to claim 2, characterized in that the directions of the direct current flowing through the first, second, and third-phase current lines from the power source to the three-phase motor are the same in the α-phase arrangement plane.

4. The current detection device according to claim 2, characterized in that the first-phase current line is orthogonal to the α-phase arrangement plane at a point other than the α-phase arrangement line.

5. The current detection device according to claim 2, wherein the β-phase magnetic detection element is arranged on a virtual β-phase arrangement line that is orthogonal to and bisects a β-phase line segment connecting the second-phase current line and the third-phase current line within the β-phase arrangement plane.

6. The current detection device according to claim 5, characterized in that the distance along the β-phase arrangement plane between the β-phase magnetic detection element and the first-phase current line is longer than the distance along the β-phase arrangement plane between the β-phase magnetic detection element and the second or third-phase current line.

7. The current detection device according to claim 6, wherein a detection axis of the β-phase magnetic detection element is orthogonal to a magnetic flux formed in the β-phase arrangement plane by a current flowing through the first-phase current line.

8. The current detection device according to any one of claims 1 to 7, further comprising arithmetic means for outputting, as a β-phase current value, a value obtained by multiplying an output value of the β-phase magnetic detection element by a β-phase gain, and outputting, as an α-phase current value, a value obtained by multiplying an output value of the α-phase magnetic detection element by an α-phase gain having a value different from the β-phase gain.

9. The current detection device according to claim 8, wherein values of the α-phase and β-phase gains are set such that amplitudes of the α-phase and β-phase current values become equal.

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