Current detection device

Abstract

The invention provides a current detection device for a three-phase motor, which can reduce the calculation load in a motor control device at the later stage of vector control. Current flowing through each phase current line (6u, 6v, 6w) of a motor (M) is detected on the basis of alpha-phase and beta-phase magnetic detection elements (S alpha, S beta) provided around the three phase current lines (6u, 6v, 6w). A virtual plane orthogonal to the three phase current lines (6u, 6v, 6w) is defined as an alpha-phase arrangement plane (Palpha), and a virtual plane orthogonal to at least the V-phase and W-phase current lines (6v, 6w) and different from the alpha-phase arrangement plane (Palpha) is defined as a beta-phase arrangement plane (Pbeta). The phase magnetic detection elements (S alpha, S beta) are provided at positions where an alpha-phase layout conditional expression and a beta-phase layout conditional expression, which are defined using a coefficient (X) other than '-1 / 2', are established in the alpha-phase and beta-phase arrangement surfaces (P alpha, P beta), respectively.

Description

Technical Field

[0001] The present invention relates to a current detection device, and more particularly, to a current detection device that detects the current of each phase of a three-phase motor using two magnetic detection elements. Background Art

[0002] In recent years, efforts to achieve a low-carbon society or a decarbonized society have become increasingly active, and research and development related to electric vehicles has also been carried out in the automotive field to reduce CO2 emissions and improve energy efficiency.

[0003] Vector control is a widely used control method for three-phase AC motors installed in electric vehicles and household appliances (e.g., air conditioners and washing machines). In vector control, a motor control device generates a command signal for the inverter based on feedback control of the d-axis and q-axis currents defined in the motor's rotating orthogonal coordinate system, i.e., the dq coordinate system.

[0004] [Background Art Literature]

[0005] [Patent Document]

[0006] Patent Document 1: International Publication No. 2013 / 058282

[0007] Patent Document 2: Chinese Patent Application CN202211040361.X Summary of the Invention

[0008] [Problems to be solved by the invention]

[0009] Thus, in order to perform current feedback control in the dq coordinate system, a motor control device must convert the motor's U-phase, V-phase, and W-phase currents, detected by a current detection device such as that described in Patent Document 1, into d-axis and q-axis currents. More specifically, the motor control device first uses a Clarke transformation to convert the three-phase currents (Iu, Iv, Iw) detected by the current detection device into two-phase currents (Iα, Iβ) defined in a fixed coordinate system. Then, using a Park transformation using the motor's rotation angle θ, these two-phase currents (Iα, Iβ) are converted into two-phase currents (Id, Iq) defined in the dq coordinate system. Thus, in vector control using the output of a conventional current detection device, the motor control device must perform the operation of converting the three-phase currents (Iu, Iv, Iw) into two-phase currents (Id, Iq).

[0010] Furthermore, Patent Document 2, filed by the applicant of this application, describes a technique for directly obtaining two-phase currents (Iα, Iβ) by placing two magnetic detection elements at geometrically defined positions around three phase current lines, without requiring a Clarke transform performed by a computer (hereinafter referred to as the "spatial Clarke transform"). This spatial Clarke transform reduces the number of magnetic detection elements and reduces the computational load on the computer compared to conventional techniques.

[0011] However, the spatial Clarke transform shown in Patent Document 2 limits the layout of the three phase current lines or two magnetic detection elements to a few specific configurations. Since various components must be efficiently arranged in electric vehicles, it is desirable to have as much freedom as possible in the layout of the phase current lines or magnetic detection elements.

[0012] 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 motor control device that performs vector control, thereby contributing to improved energy efficiency.

[0013] [Technical means to solve the problem]

[0014] (1) The current detection device of the present invention (e.g., the current detection device 3 described later) is based on an α-phase magnetic detection element (e.g., the α-phase magnetic detection element Sα described later) and a β-phase magnetic detection element (e.g., the β-phase magnetic detection element Sβ described later) provided around a first-phase current line (e.g., the U-phase current line 6u described later), a second-phase current line (e.g., the V-phase current line 6v described later), and a third-phase current line (e.g., the W-phase current line 6w described later) of a three-phase motor (e.g., the motor M described later), to detect the current flowing through the first-phase current line, the second-phase current line, and the third-phase current line. The current detection device is characterized in that, when the current value flowing through the first-phase current line is set to I1, the current value flowing through the second-phase current line is set to I2. When the current value is set to I2, the current value flowing through the third-phase current line is set to I3, the output value of the α-phase magnetic detection element is set to Vα, the output value of the β-phase magnetic detection element is set to Vβ, and an imaginary surface orthogonal to the first-phase current line, the second-phase current line, and the third-phase current line is set to the α-phase configuration surface (for example, the α-phase configuration surface Pα described later), and an imaginary surface orthogonal to at least the second-phase current line and the third-phase current line and different from the α-phase configuration surface is set to the β-phase configuration surface (for example, the β-phase configuration surface Pβ described later), the α-phase and β-phase magnetic detection elements are respectively provided at positions within the α-phase and β-phase configuration surfaces where the following equations (1-1) and (1-2) are satisfied, as defined by a coefficient X other than "-1 / 2":

[0015] [Number 1]

[0016]

[0017] (2) In this case, the α-phase magnetic detection element is preferably arranged within the α-phase configuration plane on an imaginary α-phase configuration line (e.g., the α-phase configuration line Lα described later) that is orthogonal to the α-phase line segment connecting the second-phase current line and the third-phase current line (e.g., the α-phase line segment L1 described later) and divides the α-phase line segment into two equal parts.

[0018] (3) In this case, it is preferred that the first phase current line is orthogonal to the α-phase configuration plane at the intersection of the α-phase line segment and the α-phase configuration line, and the direction of the direct current flowing from the power supply toward the three-phase motor through the first phase current line, the second phase current line and the third phase current line is the same in the α-phase configuration plane.

[0019] (4) In this case, it is preferable that the first phase current line is perpendicular to the α-phase arrangement plane at points other than the α-phase arrangement line (for example, points P1, P2, P3, and P4 described later).

[0020] (5) In this case, the β-phase magnetic detection element is preferably arranged within the β-phase configuration plane on an imaginary β-phase configuration line (e.g., the β-phase configuration line Lβ described later) that is orthogonal to the β-phase line segment (e.g., the β-phase line segment L2 described later) connecting the second-phase current line and the third-phase current line and that divides the β-phase line segment into two equal parts.

[0021] (6) In this case, the distance between the β-phase magnetic detection element and the first phase current line along the β-phase configuration plane is preferably longer than the distance between the β-phase magnetic detection element and the second phase current line or the third phase current line along the β-phase configuration plane.

[0022] (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 orthogonal to the magnetic flux formed in the β-phase arrangement plane by the current flowing through the first-phase current line.

[0023] (8) In this case, it is preferred to further include an operation mechanism (for example, the current correction operation unit 22 described later), which outputs a value obtained by multiplying the output value of the β-phase magnetic detection element by the β-phase gain (for example, the β-phase gain Gβ described later) as a β-phase current value (for example, the β-phase current value Iβ described later), and outputs a value obtained by multiplying the output value of the α-phase magnetic detection element by an α-phase gain different from the β-phase gain (for example, the α-phase gain Gα described later) as an α-phase current value (for example, the α-phase current value Iα described later).

[0024] (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 become equal.

[0025] [Effects of the Invention]

[0026] ((1) In the current detection device of the present invention, the current flowing through the three current lines is detected based on two magnetic detection elements provided around the three 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 a magnetic detection element is provided for each current line, and thus the cost can be reduced accordingly. Furthermore, in the current detection device of the present invention, the α-phase and β-phase magnetic detection elements are provided at positions where the above-mentioned equations (1-1) and (1-2) defined by the coefficient X other than "-1 / 2" hold. On the other hand, in the Chinese patent application CN202 filed by the applicant of the present application, In the spatial Clarke transform described in 211040361.X (hereinafter referred to as the "prior application"), the relative positions of the α-phase and β-phase magnetic detection elements with respect to the first to third-phase current lines and the direction of the detection axis are defined in a manner such that a matrix operation equivalent to the Clarke transform holds (i.e., equivalent to the case where X = 1 in equations (1-1) and (1-2)). Therefore, according to the present invention, since equations (1-1) and (1-2) include the arbitrary coefficient X, the layout of the three phase current lines and the two magnetic detection elements can be more flexible than in the conventional spatial Clarke transform.

[0027] Furthermore, as described in detail later, the current resulting from multiplying the three-phase currents (I1, I2, I3) with a phase difference of 2π / 3 by the transformation matrix (X, -1 / 2, -1 / 2) described in equation (1-1) differs only in amplitude, but has the same phase, from the current resulting from multiplying the three-phase currents (I1, I2, I3) by the first row component (1, -1 / 2, -1 / 2) of the transformation matrix for the Clarke transform. This means that the output value Vα of the α-phase magnetic detection element, configured so that equation (1-1) holds true, can be made equal to the output value of the magnetic detection element described in the prior application by multiplying it by a predetermined gain. Therefore, the current detection device of the present invention, by using the output values of two magnetic detection elements, eliminates the need for Clarke transform calculations in a subsequent motor control device, thereby reducing the computational load of the motor control device and improving energy efficiency.

[0028] In addition, as shown in the above formula (1-2), the β-phase magnetic detection element needs to be set 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 configuration plane orthogonal to the three phase current lines in a manner that satisfies the above formulas (1-1) and (1-2), 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 the α-phase configuration plane orthogonal to the first phase current line, the second phase current line and the third phase current line, and the β-phase magnetic detection element is arranged in the β-phase configuration plane orthogonal to at least the second phase current line and the third phase current line and different from the α-phase configuration plane. Therefore, according to the present invention, compared with the case where the two magnetic detection elements are arranged in a common configuration plane, the degree of freedom of the configuration layout of the three phase current lines and the two magnetic detection elements can be further improved.

[0029] (2) In the present invention, by arranging the α-phase magnetic detection element on an imaginary α-phase configuration line within the α-phase configuration plane that is orthogonal to the α-phase line segment connecting the second-phase current line and the third-phase current line and divides the α-phase line segment into two equal parts, the α-phase magnetic detection element can be arranged at a free position corresponding to the requirements while making the above-mentioned formula (1-1) valid.

[0030] (3) In the present invention, by arranging the first phase current line, the second phase current line, and the third phase current line side by side in the α phase configuration plane, the three phase current lines can be compactly integrated while making the above formula (1-1) valid. In addition, in the spatial Clarke transformation described in the prior application, although the three phase current lines can also be arranged side by side, it is necessary to make the direction of the phase current line arranged in the center opposite to the other two (refer to the prior application). Figure 4 and Figure 5 ), so the phase current lines need to be twisted. In contrast, according to the present invention, three phase current lines can be arranged in parallel without twisting the phase current lines.

[0031] (4) In the present invention, by setting the first phase current line at a position perpendicular 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 equation (1-1).

[0032] (5) In the present invention, by arranging the β-phase magnetic detection element on an imaginary β-phase configuration line within the β-phase configuration plane that is orthogonal to the β-phase line segment connecting the second-phase current line and the third-phase current line and divides the β-phase line segment into two equal parts, the β-phase magnetic detection element can be arranged at a free position corresponding to the requirements while making the above-mentioned formula (1-2) valid.

[0033] (6) In the present invention, by setting a β-phase magnetic detection element at a position where the first phase current line is farther away from the second phase current line or the third phase current line within the β-phase configuration plane, the first phase current line can be configured at a free position corresponding to the requirements while making the above-mentioned formula (1-2) valid.

[0034] (7) In the present invention, the β-phase magnetic detection element is arranged in such a manner that the detection axis of the β-phase magnetic detection element is orthogonal to the magnetic flux formed in the β-phase configuration plane due to the current flowing through the first-phase current line, thereby making it possible to arrange the β-phase magnetic detection element in a free position corresponding to the requirements while making the above-mentioned formula (1-2) valid.

[0035] (8) In the present invention, the calculation mechanism 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 calculation by the calculation mechanism can eliminate the amplitude difference between the output values of the two magnetic detection elements caused by the coefficient X included in equation (1-1). Therefore, according to the present invention, the α-phase and β-phase current values can be obtained without performing Clarke transform calculations.

[0036] (9) In the present invention, by setting the values of the α-phase and β-phase gains so 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 Clarke transform calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a diagram showing the configuration of a current detection device according to one embodiment of the present invention and an electric vehicle including the current detection device.

[0038] Figure 2 It is a side view of three phase current lines and an α-phase arrangement plane and a β-phase arrangement plane that are orthogonal to these phase current lines.

[0039] Figure 3 This is a diagram for explaining the arrangement range of α-phase magnetic detection elements that satisfies the α-phase layout conditional expression within the α-phase arrangement plane.

[0040] Figure 4 This is a diagram showing another example of the arrangement range of the α-phase magnetic detection elements that satisfies the α-phase layout conditional expression within the α-phase arrangement plane.

[0041] Figure 5 This is a diagram for explaining the arrangement range of the β-phase magnetic detection elements when the β-phase layout conditional expression is satisfied. DETAILED DESCRIPTION

[0042] Hereinafter, a current detection device according to an embodiment of the present invention and an electric vehicle equipped with the current detection device will be described with reference to the drawings.

[0043] Figure 1 This figure shows the configuration of a current detecting device 3 and an electric vehicle V equipped with the current detecting device according to this embodiment. While the following description will focus on a case where the current detecting device 3 is mounted on the electric vehicle V, the present invention is not limited thereto. In addition to the electric vehicle V, the current detecting device 3 may also be mounted on any device that controls a three-phase motor using vector control, such as an air conditioner or a washing machine.

[0044] An electric vehicle V includes: a three-phase AC motor M (hereinafter referred to as "motor M"); drive wheels W connected to the output shaft of the motor M via a power transmission mechanism (not shown); an inverter 1 connecting a battery (not shown) to the motor M; a sensor unit S that generates a signal based on 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 the sensor unit S and the resolver 4.

[0045] Inverter 1 is, for example, a PWM inverter based on pulse width modulation (PWM). It includes a bridge circuit formed by bridging multiple switching elements (e.g., IGBTs) and has the function of converting DC power into AC power. Inverter 1 is connected to a battery on its DC input and output sides and to the U-phase, V-phase, and W-phase coils of electric motor M on its AC input and output sides, converting power between the battery and electric motor M. Inverter 1 turns on and off the switching elements of each phase based on gate drive signals generated at predetermined times by a gate drive circuit (not shown). This converts DC power supplied from the battery into AC power and supplies it to electric motor M, or vice versa.

[0046] The sensor unit S includes an α-phase magnetic detection element Sα and a β-phase magnetic detection element Sβ, which are arranged around the 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 respectively generate detection signals corresponding to the components of the magnetic flux density of the magnetic field generated by the current flowing through each phase current line 6u, 6v, and 6w along each detection axis. In addition, a specific example of the configuration layout of these α-phase and β-phase magnetic detection elements Sα, Sβ and the three phase current lines 6u, 6v, and 6w will be referred to later. Figures 2 to 5 Provide explanation.

[0047] The motor control device 2 is a computer that performs vector control based on detection signals from two magnetic detection elements Sα and Sβ and the resolver 4 to generate a drive signal for the gate drive circuit of the inverter 1 and input the drive signal to the gate drive circuit.

[0048] In the motor control device 2 , as modules related to execution of the vector control as described above, an AD converter 21 , a current correction calculator 22 , a dq converter 23 , and a duty ratio calculator 24 are configured.

[0049] The AD converter 21 performs AD conversion on the detection signals of the α-phase and β-phase magnetic detection elements Sα and Sβ, thereby acquiring output values (Vα and Vβ) of the α-phase and β-phase magnetic detection elements Sα and Sβ.

[0050] As shown in the following equation (2), the current correction calculation unit 22 multiplies the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα and Sβ, respectively, obtained by the A / D conversion unit 21, by the α-phase gain Gα and the β-phase gain Gβ, and outputs the resulting values as the α-phase current value Iα and the β-phase current value Iβ. 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.

[0051] [Number 2]

[0052]

[0053] 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 currents (Iα_ideal, Iβ_ideal) obtained by multiplying the three-phase currents (Iu, Iv, Iw) of the motor M by the two-row, three-column Clarke transformation matrix shown in the following equation (3). Hereinafter, the current value flowing through the U-phase current line 6u is referred to as Iu, the current value flowing through the V-phase current line 6v is referred to as Iv, and the current value flowing through the W-phase current line 6w is referred to as Iw. Therefore, in the motor control device 2, when calculating the two-phase currents (Id, Iq) in the dq coordinate system in the dq transformation unit 23 (described later), calculations using the Clarke transformation matrix shown in the following equation (3) are no longer necessary. This significantly reduces the computational load on the motor control device 2 compared to conventional methods. Therefore, in this embodiment, the current detection device 3 that detects the current flowing through the three-phase current lines 6 u , 6 v , and 6 w of the motor M is composed of two magnetic detection elements Sα and Sβ, an AD converter 21 , and a current correction calculation unit 22 .

[0054] [Number 3]

[0055]

[0056] The dq conversion unit 23 calculates the d-axis current Id and the q-axis current Iq by performing known calculations using the output values (Iα, Iβ) of the current correction calculation unit 22 and the detection signal of the resolver 4 .

[0057] The duty cycle calculation unit 24 obtains the d-axis current command Idc and the q-axis current command Iqc corresponding to the driver's required driving force, and generates a drive signal for the gate drive circuit of the inverter 1 by performing feedback control based on the deviation of these current values (Idc-Id, Iqc-Iq) to achieve the driver's required driving force, and inputs the drive signal to the gate drive circuit.

[0058] Next, 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 satisfy the above-mentioned equation (3) will be described.

[0059] First, as described above, 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) to ensure that their amplitudes are equal. Therefore, the phase difference between the output values (Vα, Vβ) of the α-phase and β-phase magnetic detection elements Sα, Sβ must be equal to the phase difference between the two-phase currents (Iα_ideal, Iβ_ideal) obtained by equation (3). However, the amplitudes of these output values (Vα, Vβ) may differ. In other words, the difference in the amplitudes of 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) applied to the two output values (Vα, Vβ) respectively hold true, the above-mentioned equation (3) can be satisfied.

[0060] [Number 4]

[0061]

[0062] Furthermore, as described later, assuming that the current values (Iu, Iv, Iw) flowing through each phase current line 6u, 6v, and 6w have a phase difference of 2π / 3, the above equations (4-1) and (4-2) can be generalized to the following equations (5-1) and (5-2) using an arbitrary coefficient X. Therefore, in this embodiment, the layout of the three phase current lines 6u, 6v, and 6w and the two magnetic detection elements Sα and Sβ (i.e., the layout of the three phase current lines 6u, 6v, and 6w and the relative positions of the two magnetic detection elements Sα and Sβ with respect to these phase current lines 6u, 6v, and 6w, and the direction of the detection axis) are defined so that the following equations (5-1) and (5-2) are satisfied, as defined using a coefficient X other than -1. Furthermore, in a layout where the coefficient X in equation (5-1) is -1 / 2, the theoretical output value of the magnetic detection element Sα is always "0." Therefore, in the following formula (5-1), the layout in which the value of the coefficient X is "-1 / 2" is excluded.

[0063] [Number 5]

[0064]

[0065] Next, the reason why the above formula (4-1) can be generalized to the above formula (5-1) is 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, and 6w are respectively arranged at arbitrary positions is expressed by the following formula (6) using arbitrary coefficients (X, A, B). Here, the values of the coefficients (X, A, B) vary depending on the relative position of the α-phase magnetic detection element Sα with respect to the three phase current lines 6u, 6v, and 6w and the direction of the detection axis. More specifically, the value of the coefficient X is determined by 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 by 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 by 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.

[0066] [Number 6]

[0067] Vα′=X·Iu+A·Iv+B·Iw (6)

[0068] Furthermore, assuming that the current values (Iu, Iv, Iw) flowing through the respective phase current lines 6u, 6v, and 6w have a phase difference of 2π / 3 with respect to the U phase, the following equation (7) is derived using the addition theorem based on equation (6). In equation (7), Iu = sinθ, Iv = sin(θ-2π / 3), and Iw = sin(θ+2π / 3).

[0069] [Number 7]

[0070]

[0071] Here, in the above equation (7), if A=B is assumed as in the above equation (4-1), the following equation (8) is derived. The assumption of A=B is equivalent to arranging the phase current lines 6v, 6w, and the α-phase magnetic detection element Sα at positions such that the distance between the V-phase current line 6v and the α-phase magnetic detection element Sα is equal to the distance between the W-phase current line 6w and the α-phase magnetic detection element Sα, and 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.

[0072] [Number 8]

[0073] Vα′=(XA)·sinθ (8)

[0074] As shown in equation (8), assuming A = B, the term cosθ disappears from equation (7), and the output value Vα′ of the α-phase magnetic detection element Sα is proportional only to sinθ. This means that, as long as A = B, the phase of the output value Vα′ remains unchanged regardless of changes in the relative position of the α-phase magnetic detection element Sα with respect to the U-phase current line 6u or the direction of the detection axis (i.e., regardless of changes in the value of X). In other words, within the range of A = B, only the amplitude of the output value Vα′ changes regardless of changes in the relative position of the α-phase magnetic detection element Sα with respect to the U-phase current line 6u or the direction of the detection axis (i.e., regardless of changes in the value of X). Furthermore, as shown in equation (8), when the α-phase magnetic detection element Sα is positioned at a position where all coefficients are equal (i.e., at a position where X = A = B), the output value Vα′ is always "0." For the reasons described above, equation (4-1) can be generalized to equation (5-1) using any coefficient X other than "-1 / 2."

[0075] Next, the layout of the three phase current lines 6u, 6v, and 6w and the two magnetic detection elements Sα and Sβ that satisfy equations (5-1) and (5-2) will be described. Hereinafter, equation (5-1) applied to the output value Vα of the α-phase magnetic detection element Sα will be referred to as the α-phase layout conditional equation, and equation (5-2) applied to the output value Vβ of the β-phase magnetic detection element Sβ will be referred to as the β-phase layout conditional equation.

[0076] Figure 2 : is a side view of the three phase current lines 6u, 6v, 6w and the α-phase configuration plane Pα and the β-phase configuration plane Pβ that are orthogonal to these phase current lines. Figure 2In the following description, the α-phase magnetic detection element Sα is disposed within a hypothetical α-phase arrangement plane Pα, which is perpendicular to the three phase current lines 6u, 6v, and 6w, and the β-phase magnetic detection element Sβ is disposed within a β-phase arrangement plane Pβ, which is perpendicular to at least two phase current lines 6v and 6w and is different from the α-phase arrangement plane Pα. However, the present invention is not limited to this configuration. These two magnetic detection elements Sα and Sβ may also be disposed together within the same α-phase arrangement plane Pα.

[0077] Figure 3 : is a diagram schematically showing the α-phase arrangement surface Pα where the α-phase magnetic detection element Sα is provided. More specifically, Figure 3 This is a diagram for explaining the arrangement range of the α-phase magnetic detection element Sα that satisfies the α-phase layout conditional formula (5-1) within the α-phase arrangement plane Pα. Figure 3 The figure shows that the three phase current lines 6u, 6v, and 6w are arranged side by side at equal intervals in the order of V-phase current line 6v, U-phase current line 6u, and W-phase current line 6w within the α-phase arrangement plane Pα, but the present invention is not limited to this. Figure 3 , the direction of the DC current flowing from the inverter 1 as the power source to the motor M through the respective phase current lines 6u, 6v, and 6w is made the same in the α-phase arrangement plane Pα, but the present invention is not limited thereto.

[0078] First, in order for the α-phase layout conditional expression (5-1) to hold, the α-phase magnetic detection element Sα must be located within the α-phase layout plane Pα on a virtual α-phase layout line Lα that is orthogonal to the virtual α-phase line segment L1 connecting the V-phase current line 6v and the W-phase current line 6w and bisects this α-phase line segment L1. Specifically, the α-phase magnetic detection element Sα must be located within the α-phase layout plane Pα at a position equidistant from the V-phase current line 6v and the W-phase current line 6w (i.e., on the α-phase layout line Lα).

[0079] Furthermore, in order to make the α-phase layout condition (5-1) valid, Figure 3 As shown in the example, the detection axis Oα of the α-phase magnetic detection element Sα must be perpendicular to the α-phase arrangement line Lα within the α-phase arrangement plane Pα. 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 arrangement line Lα, the detection axis Oα will be perpendicular to the magnetic flux formed by the phase current lines 6v and 6w. Therefore, the α-phase magnetic detection element Sα must be placed at a position on the α-phase arrangement line Lα other than the intersection with the α-phase line segment L1.

[0080] Furthermore, as mentioned above, the α-phase layout conditional expression (5-1) includes an arbitrary coefficient X. Therefore, the U-phase current line 6u can also be set at any position within the α-phase layout plane Pα, excluding the dead point P0 where the coefficient X is "-1 / 2". That is, the U-phase current line 6u is not limited to the position within the α-phase layout plane Pα. Figure 3 Even if the midpoints of the α-phase line segment L1 shown in FIG. 1 are set at a position perpendicular to the α-phase configuration plane Pα at a point other than the α-phase configuration line Lα, the α-phase layout conditional expression (5-1) still holds. Here, the insensitive point P0 is the configuration position of the U-phase current line 6u where the output value Vα of the α-phase magnetic detection element Sα is always "0" as described above. When the α-phase magnetic detection element Sα and the v-phase and w-phase current lines 6v and 6w are set at Figure 3 In the case of the position shown, Figure 3 As shown, the zero-inductance point P0 is shown on the α-phase arrangement line Lα.

[0081] Figure 4 5-1 is a diagram showing another example of the arrangement range of the α-phase magnetic detection elements Sα that satisfies the α-phase layout conditional expression (5-1) within the α-phase arrangement plane Pα.

[0082] In addition, with Figure 3 The example is different. Figure 4 3 shows a case where the current lines 6u, 6v, and 6w of each phase are arranged at the corners of an isosceles triangle whose apex angle is the U-phase current line 6u.

[0083] like Figure 4 As shown, even if the three phase current lines 6u, 6v, and 6w are arranged at the corners of an isosceles triangle within the α-phase configuration plane Pα, the α-phase magnetic detection element Sα can be arranged on the α-phase configuration line Lα in a manner that makes the detection axis Oα orthogonal to the α-phase configuration line Lα, so that the α-phase layout conditional formula (5-1) can be established.

[0084] Figure 5 : is a diagram schematically showing a β-phase arrangement plane Pβ on which β-phase magnetic detection elements Sβ are provided. More specifically, Figure 5 This is a diagram for explaining the arrangement range of the β-phase magnetic detection element Sβ that satisfies the β-phase layout conditional formula (5-2) within the β-phase arrangement plane Pβ. Figure 5 , the case where the directions of the DC currents flowing from the inverter 1 as the power source to the motor M through the respective phase current lines 6v, 6w are made the same in the β-phase arrangement plane Pβ is shown, but the present invention is not limited thereto.

[0085] First, in order for β-phase layout conditional equation (5-2) to hold, β-phase magnetic detection element Sβ must be positioned within β-phase layout plane Pβ on a virtual β-phase layout line Lβ that is orthogonal to virtual β-phase line segment L2 connecting V-phase current line 6v and W-phase current line 6w and bisects this β-phase line segment L2. Specifically, β-phase magnetic detection element Sβ must be positioned within β-phase layout plane Pβ at an equal distance from V-phase current line 6v and W-phase current line 6w (i.e., on β-phase layout line Lβ).

[0086] Furthermore, in order to make the β-phase layout condition (5-2) valid, Figure 5 As illustrated, the detection axis Oβ of the β-phase magnetic detection element Sβ must be parallel to the β-phase arrangement line Lβ within the β-phase arrangement plane Pβ.

[0087] Furthermore, in order for the β-phase layout conditional equation (5-2) to hold, the β-phase magnetic detection element Sβ must be positioned in a position that is unaffected by the magnetic flux generated within the β-phase arrangement plane Pβ by the current flowing through the unillustrated U-phase current line 6u. This can be achieved, for example, by making the distance along the β-phase arrangement plane Pβ between the β-phase magnetic detection element Sβ and the unillustrated U-phase current line 6u sufficiently longer than the distance along the β-phase arrangement plane Pβ between the β-phase magnetic detection element Sβ and the V-phase current line 6v or the W-phase current line 6w. Furthermore, if the U-phase current line 6u is arranged to be perpendicular to the β-phase arrangement plane Pβ at the intersection P5 of the β-phase line segment L2 and the β-phase arrangement line Lβ, this can also be achieved by arranging the detection axis Oβ of the β-phase magnetic detection element Sβ parallel to the β-phase arrangement line Lβ and perpendicular to the magnetic flux generated within the β-phase arrangement plane Pβ by the current flowing through the U-phase current line 6u.

[0088] Furthermore, in order for the β-phase layout conditional expression (5-2) to hold, the detection axis Oβ of the β-phase magnetic detection element Sβ must be orthogonal to the magnetic flux formed by the current flowing through the U-phase current line 6u. Figure 3 When the three phase current lines 6u, 6v, and 6w are arranged side by side at equal intervals as shown, in order to satisfy the β-phase layout condition (5-2), the detection axis Oβ of the β-phase magnetic detection element Sβ must be as follows: Figure 3 As shown in the example, it is parallel to the α-phase arrangement line Lα within the arrangement plane P. Therefore, the β-phase magnetic detection element Sβ is arranged on the α-phase arrangement line Lα so that its detection axis Oβ is parallel to the α-phase arrangement line Lα, thereby satisfying the β-phase layout conditional expression (5-2).

[0089] According to the current detection device 3 of this embodiment, the following effects are achieved.

[0090] (1) In the current detection device 3, the current flowing through the three phase current lines 6u, 6v, and 6w is detected based on two magnetic detection elements Sα and Sβ arranged around these phase current lines 6u, 6v, and 6w. Therefore, according to the current detection device 3, the number of magnetic detection elements can be reduced compared to the existing current detection device in which a magnetic detection element is provided for each current line, thereby reducing costs accordingly. Moreover, in the current detection device 3, the α-phase magnetic detection element Sα and the β-phase magnetic detection element Sβ are respectively provided in the α-phase configuration plane Pα and the β-phase configuration plane Pβ at positions where the α-phase layout conditional expression (5-1) and the β-phase layout conditional expression (5-2) specified by the coefficient X other than "-1 / 2" are satisfied. Therefore, according to the current detection device 3, since the equations (5-1) and (5-2) include an arbitrary coefficient X, compared with the spatial Clarke transform recorded in the prior application of the applicant of this application, the freedom of the configuration layout of the three phase current lines 6u, 6v, 6w and the two magnetic detection elements Sα, Sβ can be increased.

[0091] As described above, the current resulting from multiplying the three-phase currents (Iu, Iv, Iw) with a phase difference of 2π / 3 by the transformation matrix (X, -1 / 2, -1 / 2) described in the α-phase layout conditional equation (5-1) differs only in amplitude, but has the same phase, as the current resulting from multiplying the three-phase currents (Iu, Iv, Iw) by the first row component (1, -1 / 2, -1 / 2) of the Clarke transform transformation matrix. This means that the output value Vα of the α-phase magnetic detection element Sα, which is configured so that the α-phase layout conditional equation (5-1) holds, can be made equal to the output value of the first magnetic detection element described in the prior application by multiplying it 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, the motor control device 2, which is provided downstream, does not need to perform a Clarke transform. This can reduce the computational load of the motor control device 2, thereby contributing to improved energy efficiency.

[0092] Furthermore, as shown in the β-phase layout conditional equation (5-2), the β-phase magnetic detection element Sβ must be located in a position unaffected by the current flowing through the U-phase current line 6u. Therefore, when the α-phase and β-phase magnetic detection elements Sα and Sβ are arranged within the same α-phase arrangement plane Pα, which is orthogonal to the three-phase current lines 6u, 6v, and 6w, in a manner that satisfies the α-phase layout conditional equation (5-1) and the β-phase layout conditional equation (5-2), the locations where the β-phase magnetic detection element Sβ can be arranged are limited. Therefore, in the current detection device 3, the α-phase magnetic detection element Sα is arranged within the α-phase arrangement plane Pα, which is orthogonal to the three-phase current lines 6u, 6v, and 6w, and the β-phase magnetic detection element Sβ is arranged within the β-phase arrangement plane Pβ, which 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 in the arrangement layout of the three phase current lines 6u, 6v, and 6w and the two magnetic detection elements Sα and Sβ can be further improved.

[0093] (2) In the current detection device 3, by arranging the α-phase magnetic detection element Sα on an imaginary α-phase configuration line Lα within the α-phase configuration surface Pα, which is orthogonal to the α-phase line segment L1 connecting the V-phase and W-phase current lines 6v and 6w and divides the α-phase line segment L1 into two equal parts, the α-phase magnetic detection element Sα can be arranged at a free position corresponding to the requirements while making the α-phase layout conditional expression (5-1) valid.

[0094] (3) In the current detection device 3, by arranging the three phase current lines 6u, 6v, and 6w side by side in the α-phase arrangement plane Pα, the three phase current lines 6u, 6v, and 6w can be compactly integrated while satisfying the α-phase layout conditional expression (5-1). In addition, in the spatial Clarke transformation described in the prior application, although the three phase current lines 6u, 6v, and 6w can also be arranged side by side, it is necessary to make the direction of the U-phase current line 6u arranged in the center opposite to the other two (refer to the prior application). Figure 4 and Figure 5 ), 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 in parallel without twisting the phase current lines.

[0095] (4) In the current detection device 3, by setting the U-phase current line 6u at a position orthogonal to the α-phase configuration plane Pα at a point other than the α-phase configuration line Lα, the U-phase current line 6u can be arranged at a free position while making the α-phase layout conditional expression (5-1) valid.

[0096] (5) In the current detection device 3, by arranging the β-phase magnetic detection element Sβ on an imaginary β-phase configuration line Lβ within the β-phase configuration surface Pβ, which is orthogonal to the β-phase line segment L2 connecting the V-phase and W-phase current lines 6v and 6w and divides the β-phase line segment L2 into two equal parts, the β-phase magnetic detection element Sβ can be arranged at a free position corresponding to the requirements while making the β-phase layout conditional expression (5-2) hold.

[0097] (6) In the current detection device 3, by setting the β-phase magnetic detection element Sβ at a position farther away from the U-phase current line 6u than the V-phase or W-phase current lines 6v, 6w within the β-phase configuration surface Pβ, the U-phase current line 6u can be configured at a free position corresponding to the requirements while making the β-phase layout conditional expression (5-2) valid.

[0098] (7) In the current detection device 3, the β-phase magnetic detection element Sβ is arranged in such a manner that the detection axis Oβ of the β-phase magnetic detection element Sβ is orthogonal to the magnetic flux formed in the β-phase configuration surface Pβ due to the current flowing through the U-phase current line 6u, thereby making it possible to arrange the β-phase magnetic detection element Sβ in a free position corresponding to the requirements while making the β-phase layout conditional expression (5-2) hold true.

[0099] (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, respectively, by the α-phase and β-phase gains (Gα, Gβ). Therefore, in the current detection device 3, the calculation performed by the current correction calculation unit 22 can eliminate the amplitude difference 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 equation (5-1). Therefore, according to the current detection device 3, the α-phase and β-phase current values can be obtained without performing Clarke transform calculations.

[0100] (9) In the current detection device 3, by setting the values of the α-phase and β-phase gains (Gα, Gβ) so that the amplitudes of the α-phase and β-phase current values (Iα, Iβ) are equal, the α-phase and β-phase current values (Iα, Iβ) can be obtained without performing Clarke transform calculations.

[0101] While one embodiment of the present invention has been described above, the present invention is not limited thereto and the detailed configuration may be appropriately modified within the scope of the gist of the present invention.

[0102] Reference numerals

[0103] 1: Inverter (power supply)

[0104] 2: Motor control device

[0105] 3: Current detection device

[0106] 4: Rotary transformer

[0107] 6u: U phase current line (first phase current line)

[0108] 6v: V phase current line (second phase current line)

[0109] 6w:W phase current line (third phase current line)

[0110] 21: AD conversion unit

[0111] 22: Current correction calculation unit (calculation mechanism)

[0112] 23: dq conversion unit

[0113] 24: Duty cycle calculation unit

[0114] L1: α phase segment

[0115] L2: β phase segment

[0116] Lα: α phase configuration line

[0117] Lβ:β phase configuration line

[0118] M: Electric motor (three-phase motor)

[0119] Oα: Detection axis

[0120] Oβ: Detection axis

[0121] Pα:α phase configuration plane

[0122] Pβ:β phase configuration plane

[0123] Sα: α-phase magnetic detection element

[0124] Sβ:β-phase magnetic detection element

[0125] V: Vehicle

[0126] W: driving wheel

Claims

1. A current detection device for detecting current flowing through a first current line, a second current line, and a third current line of a three-phase motor using an α-phase magnetic detection element and a β-phase magnetic detection element disposed around the first current line, the second current line, and the third current line of the three-phase motor, wherein: When the current value flowing through the first-phase current line is set to I1, the current value flowing through the second-phase current line is set to I2, and the current value flowing through the third-phase current line is set to I3, the output value of the α-phase magnetic detection element is set to Vα, the output value of the β-phase magnetic detection element is set to Vβ, an imaginary plane orthogonal to the first-phase current line, the second-phase current line, and the third-phase current line is set to the α-phase arrangement plane, and an imaginary plane orthogonal to at least the second-phase current line and the third-phase current line and different from the α-phase arrangement plane is set to the β-phase arrangement plane, the α-phase and β-phase magnetic detection elements are respectively provided at positions within the α-phase and β-phase arrangement planes where the following equations (1-1) and (1-2) are satisfied, as defined by a coefficient X other than "-1 / 2": [Number 1] 2. The current detection device according to claim 1, characterized in that The α-phase magnetic detection element is arranged on a virtual α-phase arrangement line that is orthogonal to the α-phase line segment connecting the second-phase current line and the third-phase current line and bisects the α-phase line segment in the α-phase arrangement plane.

3. The current detection device according to claim 2, characterized in that: The first phase current line is perpendicular to the α-phase arrangement plane at the intersection of the α-phase line segment and the α-phase arrangement line. Directions of direct currents flowing from a power source toward the three-phase motor through the first-phase current line, the second-phase current line, and the third-phase current line 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 perpendicular 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, characterized in that: The β-phase magnetic detection element is arranged on a virtual β-phase arrangement line that is orthogonal to a β-phase line segment connecting the second-phase current line and the third-phase current line and bisects the β-phase line segment in the β-phase arrangement plane.

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

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

8. The current detection device according to any one of claims 1 to 7, characterized in that: It also includes an operation mechanism, which outputs the value obtained by multiplying the output value of the β-phase magnetic detection element by the β-phase gain as the β-phase current value, and outputs the value obtained by multiplying the output value of the α-phase magnetic detection element by the α-phase gain different from the β-phase gain as the α-phase current value.

9. The current detection device according to claim 8, characterized in 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.

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