Motor drive device equipped with a detection unit that detects motor drive current

Abstract

This motor driving device comprises a first resistance part and a second resistance part having a shunt resistance connected to a first wiring pattern connected to a power element and a second wiring pattern connected to a terminal of a motor in a region in which the wiring direction of the first wiring pattern and the wiring direction of the second wiring pattern are parallel, and a detection unit for detecting a motor driving current flowing between the first wiring pattern and the second wiring pattern on the basis of a potential difference between a first potential detection point on the first wiring pattern and a second potential detection point on the second wiring pattern, the resistance value between the first resistance part and the first potential detection point on the first wiring pattern and the resistance value between the first resistance part and the second potential detection point on the second wiring pattern being substantially equal, and the resistance value between the first potential detection point and the second resistance part on the first wiring pattern and the resistance value between the second potential detection point and the second resistance part on the second wiring pattern being substantially equal.

Description

[Technical Field]

[0001] The present invention relates to a motor drive device that includes a detection unit that detects a motor drive current. [Background technology]

[0002] There are three types of current detection circuits: shunt resistor type, Hall element type, and core type. Of these, shunt resistor type current detection circuits detect current from the potential difference across a shunt resistor that occurs when a current flows through the shunt resistor.

[0003] For example, there is known an electronic circuit device having a shunt resistor, characterized in that it comprises a substrate (21) made of a dielectric, first wiring patterns (26, 27) provided on the surface of the substrate (21), a first shunt resistor (22a) provided on the surface of the substrate (21) and electrically connected to the first wiring patterns (26, 27), second wiring patterns (36, 37) provided on the back surface of the substrate (21), a second shunt resistor (22b) provided on the back surface of the substrate (21) and electrically connected to the second wiring patterns (36, 37), and vias (24) that penetrate the substrate (21) on the current inflow side and current outflow side and electrically connect the first wiring patterns (26, 27) and the second wiring patterns (36, 37) (see, for example, Patent Document 1).

[0004] For example, there is known a current detection circuit comprising: a first resistor group consisting of a plurality of resistors; a second resistor group consisting of a plurality of the resistors connected to the first resistor group; a first circuit connected to an input electrode of each of the resistors in the first resistor group; a second circuit connected to an output electrode of each of the resistors in the second resistor group; a first detection signal line connected to one of the resistors in the first resistor group for detecting a current flowing through the resistor; and a second detection signal line connected to one of the resistors in the second resistor group for detecting a current flowing through the resistor, wherein the first detection signal line and the second detection signal line are connected to the resistors in the first resistor group and the resistors in the second resistor group, the proportions of current flowing through the resistors being the same based on the configurations of the first circuit and the second circuit (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-115834 [Patent Document 2] Japanese Patent Publication No. 2020-144055 Summary of the Invention [Problem to be solved by the invention]

[0006] In shunt resistor-based current detection circuits, the greater the current flowing through the shunt resistor, the greater the heat generated. Therefore, wiring and components must be mounted with sufficient clearance around the shunt resistor, imposing significant design constraints. For this reason, shunt resistor-based current detection circuits were previously considered unsuitable for detecting large currents. However, recent advances in high-loss surface-mount resistor technology have made it possible to ensure both heat dissipation and design flexibility by connecting multiple shunt resistors in parallel. For example, the motor drive current flowing from a power conversion device such as an inverter to a motor is generally large, and shunt resistor-based current detection circuits are increasingly being used in motor drive devices.

[0007] On the other hand, shunt resistor-based current detection circuits detect current from the potential difference across the shunt resistor when current is applied, so accurate current detection requires knowing the shunt resistor's accurate resistance value. However, if the shunt resistor's resistance value is reduced to suppress heat generation when detecting a large motor drive current, the current detection circuit becomes susceptible to the resistance component of the wiring pattern on which it is installed, making it difficult to accurately detect the motor drive current and affecting motor controllability. Therefore, there is a demand for a motor drive device equipped with a shunt resistor-based current detection circuit that can accurately detect the motor drive current without compromising the freedom of wiring pattern routing. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, a motor drive device includes: a first wiring pattern electrically connected to a power element provided in the power conversion device; a second wiring pattern electrically connected to a terminal of a motor driven by the power conversion device; a first resistor section and a second resistor section each having one shunt resistor or a plurality of shunt resistors connected in parallel, wherein, in a region where the wiring direction of the first wiring pattern and the wiring direction of the second wiring pattern are substantially parallel, a first terminal of the first resistor section is electrically connected to the first wiring pattern and a second terminal of the first resistor section is electrically connected to the second wiring pattern, a first terminal of the second resistor section is electrically connected to the first wiring pattern and a second terminal of the second resistor section is electrically connected to the second wiring pattern; a detection unit that detects a motor drive current flowing between the first wiring pattern and the second wiring pattern via a shunt resistor based on a potential difference between a first potential detection point provided on the first wiring pattern between a first terminal of the first resistor section and a first terminal of the second resistor section, and a second potential detection point provided on the second wiring pattern between a second terminal of the first resistor section and a second terminal of the second resistor section; Equipped with The first wiring pattern and the second wiring pattern are arranged so that the resistance value between the first terminal of the first resistor portion and the first potential detection point on the first wiring pattern is approximately equal to the resistance value between the second terminal of the first resistor portion and the second potential detection point on the second wiring pattern, and so that the resistance value between the first potential detection point and the first terminal of the second resistor portion on the first wiring pattern is approximately equal to the resistance value between the second potential detection point and the second terminal of the second resistor portion on the second wiring pattern. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, it is possible to realize a motor drive device including a shunt resistor type current detection circuit that detects motor drive current with high accuracy without impairing the degree of freedom in routing wiring patterns. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a current detection circuit according to an embodiment of the present disclosure. [Figure 2]10 is a diagram showing a current detection circuit according to an embodiment of the present disclosure, in which a first resistance unit and a second resistance unit each include a plurality of shunt resistors. FIG. [Figure 3] 2 is a circuit diagram illustrating an equivalent circuit for the current detection circuit according to the embodiment of the present disclosure shown in FIG. 1. [Figure 4] FIG. 1 is a diagram illustrating a portion of a motor drive device including a current detection circuit according to an embodiment of the present disclosure. [Figure 5] FIG. 10 is a diagram showing a current detection circuit in which a shunt resistor is provided between two wiring patterns that have no parallel regions in the same wiring direction. [Figure 6] FIG. 6 is a circuit diagram showing an equivalent circuit of the current detection circuit shown in FIG. [Figure 7] 10A and 10B are diagrams illustrating a second method for adjusting the resistance value in the motor drive device according to the embodiment of the present disclosure. [Figure 8] 10A and 10B are diagrams illustrating a third method for adjusting the resistance value in the motor drive device according to an embodiment of the present disclosure. [Figure 9] 10A and 10B are diagrams illustrating a fourth method for adjusting the resistance value in the motor drive device according to an embodiment of the present disclosure. [Figure 10] 10 is a circuit diagram showing an equivalent circuit of the current detection circuit shown in FIG. [Figure 11] FIG. 1 is a diagram illustrating a motor drive device having a current correction function according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] A motor drive device equipped with a detection unit that detects a motor drive current will be described below with reference to the drawings. In each drawing, like components are assigned like reference symbols. Furthermore, the scale of these drawings has been changed as appropriate to facilitate understanding. The illustrated embodiment is one example for carrying out the invention, and the invention is not limited to these embodiments. Furthermore, the "motor drive current" includes both a "power running current" supplied from a power conversion device to a motor to drive the motor, and a "regenerative current" returned from the motor to the power conversion device when the motor decelerates.

[0012] <Overall configuration of current detection circuit> FIG. 1 is a diagram illustrating a current detection circuit according to one embodiment of the present disclosure.

[0013] A motor drive device according to an embodiment of the present disclosure is provided with a shunt resistor-based current detection circuit 1. The motor drive device includes a first wiring pattern 11 electrically connected to a power element (not shown) provided in a power conversion device (not shown), and a second wiring pattern 12 electrically connected to a terminal of a motor (not shown) driven by the power conversion device, which are provided, for example, on a substrate (not shown). The current detection circuit 1 is provided on a power line connecting the first wiring pattern 11 and the second wiring pattern 12.

[0014] The power conversion device is an inverter that converts power between DC power in a DC link (not shown) and AC power, which is motor drive power or regenerative power. The inverter is made up of a full-bridge circuit consisting of power elements, each consisting of a diode and a switching element connected in reverse parallel to the diode. Examples of switching elements include IGBTs, FETs, thyristors, GTOs, and transistors, but other semiconductor elements may also be used. The power elements may also be intelligent power modules (IPMs), which are power semiconductor elements incorporating drive circuits and self-protection functions, such as MOSFETs and IGBTs.

[0015] The speed, torque, or rotor position of the motor is controlled based on the motor drive current supplied from the power conversion device. In this embodiment, the type of motor is not particularly limited, and may be, for example, an induction motor or a synchronous motor. Furthermore, the number of phases of the motor is not particularly limited in this embodiment, and may be, for example, three-phase or single-phase. Machines equipped with motors include, for example, machine tools, robots, forging machines, injection molding machines, and industrial machines.

[0016] The current detection circuit 1 is provided with a shunt resistor that electrically connects the first wiring pattern 11 and the second wiring pattern 12. When the motor is in a powering state, a motor drive current (powering current) output from the power conversion device flows into the motor via the first wiring pattern 11, the shunt resistor of the current detection circuit 1, and the second wiring pattern 12. On the other hand, when the motor is in a regenerative state, a motor drive current (regenerative current) generated in the motor returns to the power conversion device via the second wiring pattern 12, the shunt resistor of the current detection circuit 1, and the first wiring pattern 11. The current detection circuit 1 detects the motor drive current flowing from the first wiring pattern 11 to the second wiring pattern 12 or from the second wiring pattern 12 to the first wiring pattern 11 via the shunt resistor.

[0017] The current detection circuit 1 includes a first resistance unit 13, a second resistance unit 14, and a detection unit 15.

[0018] The first resistance portion 13 and the second resistance portion 14 each have one shunt resistor or a plurality of shunt resistors connected in parallel. In the example shown in FIG. 1, the first resistance portion 13 and the second resistance portion 14 each are configured with one shunt resistor. In a region S (region S surrounded by a dashed line in FIG. 1) in which the wiring direction of the first wiring pattern 11 (i.e., the longitudinal direction of the first wiring pattern 11) and the wiring direction of the second wiring pattern 12 (i.e., the longitudinal direction of the second wiring pattern 12) are approximately parallel, the first resistance portion 13, the second resistance portion 14, the first wiring pattern 11, and the second wiring pattern 12 are provided on the same plane on the substrate.

[0019] The first wiring pattern 11 and the second wiring pattern 12 are electrically connected by a first resistance portion 13 and a second resistance portion 14 connected in parallel to each other in a region S where the wiring direction of the first wiring pattern 11 (i.e., the longitudinal direction of the first wiring pattern 11) and the wiring direction of the second wiring pattern 12 (i.e., the longitudinal direction of the second wiring pattern 12) are substantially parallel to each other. More specifically, in the region S where the wiring direction of the first wiring pattern 11 and the wiring direction of the second wiring pattern 12 are substantially parallel to each other, a first terminal A1 of the first resistance portion 13 is electrically connected to the first wiring pattern 11, and a second terminal A2 of the first resistance portion 13 is electrically connected to the second wiring pattern 12. Furthermore, in the region S where the wiring direction of the first wiring pattern 11 and the wiring direction of the second wiring pattern 12 are approximately parallel, the first terminal B1 of the second resistor portion 14 is electrically connected to the first wiring pattern 11, and the second terminal B2 of the second resistor portion 14 is electrically connected to the second wiring pattern 12.

[0020] In the powering state, as shown by the thick arrows in Figure 1, the motor drive current (powering current) flowing from the power element along the wiring direction (longitudinal direction) on the first wiring pattern 11 changes course at approximately right angles at the first terminal A1 of the first resistor portion 13 and the first terminal B1 of the second resistor portion 14, then changes course again at approximately right angles at the second terminal A2 of the first resistor portion 13 and the second terminal B2 of the second resistor portion 14, and then flows along the second wiring pattern 12 along the wiring direction (longitudinal direction) toward the terminals of the motor. In the regenerative state, the motor drive current (regenerative current) that flows in the wiring direction (longitudinal direction) from the motor terminal on the second wiring pattern 12 in the opposite direction to the thick arrow in Figure 1 changes course at approximately right angles at the second terminal A2 of the first resistor portion 13 and the second terminal B2 of the second resistor portion 14, then changes course again at approximately right angles at the first terminal A1 of the first resistor portion 13 and the first terminal B1 of the second resistor portion 14, and then flows on the first wiring pattern 11 in the wiring direction (longitudinal direction) toward the power element.

[0021] A first potential detection point T1 is provided on the first wiring pattern 11 between the first terminal A1 of the first resistor portion 13 and the first terminal B1 of the second resistor portion 14. In addition, a second potential detection point T2 is provided on the second wiring pattern 12 between the second terminal A2 of the first resistor portion 13 and the second terminal B2 of the second resistor portion 14.

[0022] Signal lines are routed from the first potential detection point T1 and the second potential detection point T2 to the detection unit 15. The detection unit 15 detects the motor drive current flowing between the first wiring pattern 11 and the second wiring pattern 12 via shunt resistors in the first resistance unit 13 and the second resistance unit 14 based on the potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2. The detection unit 15 includes an arithmetic processing circuit such as an IC and its peripheral circuits.

[0023] 1, each of the first resistance section 13 and the second resistance section 14 is configured with one shunt resistor, but may be configured with multiple shunt resistors connected in parallel. In this case, the number of shunt resistors constituting the first resistance section 13 and the number of shunt resistors constituting the second resistance section 14 may or may not be the same.

[0024] 2 is a diagram illustrating a current detection circuit according to an embodiment of the present disclosure, in which the first resistance section and the second resistance section each include a plurality of shunt resistors. In the example illustrated in FIG. 2, the first resistance section 13 is configured with two shunt resistors 13A and 13B connected in parallel, and the second resistance section 14 is configured with two shunt resistors 14A and 14B connected in parallel. Note that the first resistance section and the second resistance section may each be configured with three shunt resistors connected in parallel.

[0025] <Resistance requirements> Next, resistance requirements for the first wiring pattern and the second wiring pattern in an embodiment of the present disclosure will be described.

[0026] On the first wiring pattern 11, the resistance value between the first terminal A1 of the first resistor portion 13 and the first potential detection point T1, and the resistance value between the first potential detection point T1 and the first terminal B1 of the second resistor portion 14 are determined by, for example, the distance between these terminals, the shape of the first wiring pattern 11, and the material of the first wiring pattern 11. Similarly, on the second wiring pattern 12, the resistance value between the second terminal A2 of the first resistor portion 13 and the second potential detection point T2, and the resistance value between the second potential detection point T2 and the second terminal B2 of the second resistor portion 14 are determined by, for example, the distance between these terminals, the shape of the second wiring pattern 12, and the material of the second wiring pattern 12.

[0027] In a motor drive device according to an embodiment of the present disclosure, the first wiring pattern 11 and the second wiring pattern 12 are provided so that the respective resistance values have the relationship described below. Here, two forms of resistance requirements that the respective resistance values of the first wiring pattern 11 and the second wiring pattern 12 must satisfy will be listed with reference to FIG. 3.

[0028] 3 is a circuit diagram showing an equivalent circuit of the current detection circuit according to the embodiment of the present disclosure shown in FIG. 1. The resistance value of the resistance component 31 between the first terminal A1 of the first resistor unit 13 and the first potential detection point T1 on the first wiring pattern 11 is set to R1 [Ω]. The resistance value of the resistance component 32 between the first potential detection point T1 and the first terminal B1 of the second resistor unit 14 on the first wiring pattern 11 is set to R2 [Ω]. The resistance value of the resistance component 33 between the second terminal A2 of the first resistor unit 13 and the second potential detection point T2 on the second wiring pattern 12 is set to R3 [Ω]. The resistance value of the resistance component 34 between the second potential detection point T2 and the second terminal B2 of the second resistor unit 14 on the second wiring pattern 12 is set to R4 [Ω]. The resistance values of the first resistor unit 13 and the second resistor unit 14 are set to R sThe path of the current flowing from the first wiring pattern 11 through the first resistance portion 13 to the second wiring pattern 12 is a series circuit consisting of the first resistance portion 13, resistance component 33, and resistance component 34. Similarly, the path of the current flowing from the first wiring pattern 11 through the second resistance portion 14 to the second wiring pattern 12 is a series circuit consisting of resistance component 31, resistance component 32, and the second resistance portion 14. Because these series circuits are connected in parallel with each other, the current detection circuit 1 shown in FIG. 1 can be represented as an equivalent circuit as shown in FIG. 3.

[0029] First, under the resistance requirement according to the first mode, the first wiring pattern 11 and the second wiring pattern 12 are provided so that the resistance values between the respective terminals have a relationship (R1=R2=R3=R4) in which all the resistance values are approximately equal.

[0030] In the resistance requirement according to the first embodiment, the resistance value “R S +R3+R4”, and the resistance value of the combined resistance of the resistance component 31, the resistance component 32, and the second resistance section 14 “R1+R2+R S " is approximately equal to the current I flowing from the power element through the first wiring pattern 11. out [A] is divided into two parts, and the circuit consisting of the first resistor 13, the resistor 33, and the resistor 34, and the circuit consisting of the resistor 31, the resistor 32, and the second resistor 14 are respectively connected to I out At this time, the potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 is expressed as in Equation 1.

[0031]

number

[0032] Substituting "R1=R2=R3=R4" into equation 1 gives equation 2.

[0033]

number

[0034] As can be seen from Equation 2, in the case of the resistance requirements "R1 = R2 = R3 = R4" according to the first form, the potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 is the resistance value R of the shunt resistors in the first resistor unit 13 and the second resistor unit 14. s Only [Ω] is reflected, and the resistance values of the resistance components 31 to 34 are cancelled out, so that there is no influence from the resistance components of the first wiring pattern 11 and the second wiring pattern 12.

[0035] Therefore, under the connection requirement shown in Figure 1 that "the first wiring pattern 11 and the second wiring pattern 12 are electrically connected by the first resistance section 13 and the second resistance section 14 connected in parallel to each other within the region S where the wiring direction of the first wiring pattern 11 and the wiring direction of the second wiring pattern 12 are approximately parallel," by satisfying the resistance requirement "R1 = R2 = R3 = R4" according to the first form described here, it becomes possible to detect the motor drive current with high accuracy without being affected by the resistance component of the wiring pattern on which the current detection circuit 1 is provided, and therefore there is no adverse effect on motor controllability.

[0036] Furthermore, under the resistance requirements of the second form, the first wiring pattern 11 and the second wiring pattern 12 are arranged so as to have a relationship in which the resistance value R1 of the resistance component 31 between the first terminal A1 of the first resistor section 13 on the first wiring pattern 11 and the first potential detection point T1 is approximately equal to the resistance value R3 of the resistance component 33 between the second terminal A2 of the first resistor section 13 on the second wiring pattern 12 and the second potential detection point T2, and the resistance value R2 of the resistance component 32 between the first potential detection point T2 on the first wiring pattern 11 and the first terminal A1 of the second resistor section 14 is approximately equal to the resistance value R4 of the resistance component 34 between the second potential detection point T2 on the second wiring pattern 12 and the second terminal A2 of the second resistor section 14 (R1=R3 and R2=R4).

[0037] In the resistance requirement according to the second embodiment, the combined resistance of the resistance component 31, the resistance component 32, and the second resistance section 14 (resistance value “R1+R2+R S ") current I out1and the combined resistance (resistance value “R S +R3+R4) out2 The ratio of and can be expressed as in Equation 3.

[0038]

number

[0039] Substituting "R1=R3" and "R2=R4" into equation 3 gives equation 4.

[0040]

number

[0041] As can be seen from Equation 4, the combined resistance of the resistance component 31, the resistance component 32, and the second resistance section 14 (resistance value “R1+R2+R S ") current I out1 and the combined resistance (resistance value “R S +R3+R4) out2 Therefore, the potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 is expressed as in Equation 5.

[0042]

number

[0043] Substituting "R2 = R4" into equation 5 gives equation 6.

[0044]

number

[0045] As can be seen from Equation 6, in the case of the resistance requirement "R1=R3 and R2=R4" according to the second form, the potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 is the resistance value R of the shunt resistors in the first resistor section 13 and the second resistor section 14. s Only [Ω] is reflected, and the resistance values of the resistance components 31 to 34 are cancelled out, so that there is no influence from the resistance components of the first wiring pattern 11 and the second wiring pattern 12.

[0046] Therefore, under the connection requirement shown in Figure 1 that "the first wiring pattern 11 and the second wiring pattern 12 are electrically connected by the first resistance section 13 and the second resistance section 14 connected in parallel to each other within the region S where the wiring direction of the first wiring pattern 11 and the wiring direction of the second wiring pattern 12 are approximately parallel," by satisfying the resistance requirement of the second form described here, "R1 = R3 and R2 = R4," it becomes possible to detect the motor drive current with high accuracy without being affected by the resistance component of the wiring pattern on which the current detection circuit 1 is provided, and therefore there is no adverse effect on motor controllability.

[0047] In addition, when the first resistance section 13 and the second resistance section 14 each have multiple shunt resistors as shown in Figure 2, the combined resistance of the multiple shunt resistors can be calculated for each of the first resistance section 13 and the second resistance section 14, and then the resistance requirements of the first or second form described above can be applied.

[0048] As described above, according to one embodiment of the present disclosure, by configuring a motor drive device including a shunt resistor type current detection circuit 1 that satisfies the "connection requirements" and the "resistance requirements according to the first form or the second form" shown in FIG. 1, it is possible to detect the motor drive current with high accuracy without compromising the freedom of routing the wiring pattern.

[0049] <Effects of imbalance in resistance components> Next, the relationship between the imbalance in the resistance components of the first wiring pattern 11 and the second wiring pattern 12 and the error will be described using numerical examples.

[0050] For example, in FIGS. 1 and 3, it is assumed that there is an imbalance in the resistance components of the first wiring pattern 11 and the second wiring pattern 12, and that R1=R2=0.08Ω and R3=R4=0.04Ω.

[0051] The resistance values R of the first resistor 13 and the second resistor 14 s When R1 = 12 mΩ, the combined resistance of the resistance component 31, the resistance component 32, and the second resistance section 14 (resistance value R1 + R2 + R S ") current I out1 and the combined resistance (resistance value “R S +R3+R4) out2 The ratio between and can be expressed as in Equation 7.

[0052]

number

[0053] Therefore, the resistance values R of the first resistor section 13 and the second resistor section 14 are s The potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 when V is 12 mΩ is expressed by Equation 8.

[0054]

number

[0055] From Equation 8, the resistance values R of the first resistor section 13 and the second resistor section 14 are s The error ΔE [%] when = 12 mΩ can be calculated using Equation 9.

[0056]

number

[0057] On the other hand, the resistance values R of the first resistor section 13 and the second resistor section 14 sWhen R1 = 1.2 mΩ, the combined resistance of the resistance component 31, the resistance component 32, and the second resistance section 14 (resistance value R1 + R2 + R S ") current I out1 and the combined resistance (resistance value “R S +R3+R4) out2 The ratio between and can be expressed as in Equation 10.

[0058]

number

[0059] Therefore, the resistance values R of the first resistor section 13 and the second resistor section 14 are s The potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 when V ≠ 1.2 mΩ is expressed by Equation 11.

[0060]

number

[0061] From Equation 11, the resistance values R of the first resistor section 13 and the second resistor section 14 are s The error ΔE [%] when = 1.2 mΩ can be calculated using Equation 12.

[0062]

number

[0063] When there is an imbalance in the resistance components of the first wiring pattern 11 and the second wiring pattern 12, the shunt resistance of the first resistance portion 13 and the second resistance portion 14 has a resistance value R s = 12 mΩ, the error is 0.07%, as shown in Equation 9, but the error is smaller for lower resistance values R s= 1.2 mΩ, the error is 0.18%, as shown in Equation 12. In other words, if there is an imbalance in the resistance components of the first wiring pattern 11 and the second wiring pattern 12, the error will be larger as the resistance values of the shunt resistors of the first resistance unit 13 and the second resistance unit 14 become lower. According to one embodiment of the present disclosure, the first wiring pattern 11 and the second wiring pattern 12 are provided so as to satisfy the resistance requirements of the first or second form, and therefore, as shown in Equation 2 or Equation 6, the potential difference ΔV [V] between the first potential detection point T1 and the second potential detection point T2 is not affected by the resistance components of the first wiring pattern 11 and the second wiring pattern 12, and the error will not be worsened.

[0064] <Example of current detection circuit layout in a motor drive device> Next, an example of the layout of a current detection circuit in a motor drive device will be described with reference to FIG.

[0065] FIG. 4 is a diagram illustrating a portion of a motor drive device including a current detection circuit according to an embodiment of the present disclosure.

[0066] 4, an inverter main circuit 51 in a power conversion device that supplies a motor drive current to the motor includes, for example, an intelligent power module. The inverter main circuit 51 is provided with a positive-side DC terminal P to which a positive-side DC wiring pattern 42 of the DC link is electrically connected, and a negative-side DC terminal N to which a negative-side DC wiring pattern 43 of the DC link is electrically connected. The inverter main circuit 51 also is provided with a U-phase AC terminal U to which a U-phase first wiring pattern 11-1 through which a U-phase AC motor drive current flows is electrically connected, a V-phase AC terminal V to which a V-phase first wiring pattern 11-2 through which a V-phase AC motor drive current flows, and a W-phase AC terminal W to which a W-phase wiring pattern 41 through which a W-phase AC motor drive current flows.

[0067] The U-phase first wiring pattern 11-1 is electrically connected to the U-phase second wiring pattern 12-1 via the U-phase first resistor portion 13-1 and the U-phase second resistor portion 14-1. The U-phase second wiring pattern 12-1 is electrically connected to a U-phase terminal (not shown) of the motor. The U-phase first wiring pattern 11-1, the U-phase second wiring pattern 12-1, the U-phase first resistor portion 13-1, and the U-phase second resistor portion 14-1 correspond to the above-mentioned first wiring pattern 11, the second wiring pattern 12, the first resistor portion 13, and the second resistor portion 14, respectively. That is, U-phase first wiring pattern 11-1 and U-phase second wiring pattern 12-1 are electrically connected by U-phase first resistance unit 13-1 and U-phase second resistance unit 14-1 connected in parallel to each other in a region where the wiring direction of U-phase first wiring pattern 11-1 (i.e., the longitudinal direction of U-phase first wiring pattern 11-1) and the wiring direction of U-phase second wiring pattern 12-1 (i.e., the longitudinal direction of U-phase second wiring pattern 12-1) are substantially parallel. Also, U-phase first wiring pattern 11-1 and U-phase second wiring pattern 12-1 are provided so as to satisfy the resistance requirements of the first or second form described above.

[0068] Signal lines are routed from a U-phase first potential detection point provided on the U-phase first wiring pattern 11-1 and a U-phase second potential detection point provided on the U-phase second wiring pattern 12-1 to a U-phase current conversion circuit 52 constituting the above-mentioned detection unit 15. The U-phase current conversion circuit 52 includes, for example, an AD converter. The detection unit 15 in the U-phase current conversion circuit 52 detects the U-phase AC motor drive current flowing between the U-phase first wiring pattern 11-1 and the U-phase second wiring pattern 12-1 via shunt resistors in the U-phase first resistor unit 13-1 and the U-phase second resistor unit 14-1, based on a potential difference ΔV [V] between the U-phase first potential detection point and the U-phase second potential detection point.

[0069] The V-phase first wiring pattern 11-2 is electrically connected to the V-phase second wiring pattern 12-2 via the V-phase first resistor portion 13-2 and the V-phase second resistor portion 14-2. The V-phase second wiring pattern 12-2 is electrically connected to a V-phase terminal (not shown) of the motor. The V-phase first wiring pattern 11-2, the V-phase second wiring pattern 12-2, the V-phase first resistor portion 13-2, and the V-phase second resistor portion 14-2 correspond to the above-mentioned first wiring pattern 11, the second wiring pattern 12, the first resistor portion 13, and the second resistor portion 14, respectively. That is, V-phase first wiring pattern 11-2 and V-phase second wiring pattern 12-2 are electrically connected by V-phase first resistor portion 13-2 and V-phase second resistor portion 14-2 connected in parallel to each other in a region where the wiring direction of V-phase first wiring pattern 11-2 (i.e., the longitudinal direction of V-phase first wiring pattern 11-2) and the wiring direction of V-phase second wiring pattern 12-2 (i.e., the longitudinal direction of V-phase second wiring pattern 12-2) are substantially parallel. Furthermore, V-phase first wiring pattern 11-2 and V-phase second wiring pattern 12-2 are provided so as to satisfy the resistance requirements of the first or second embodiment described above.

[0070] Signal lines are routed from the V-phase first potential detection point provided on the V-phase first wiring pattern 11-2 and the V-phase second potential detection point provided on the V-phase second wiring pattern 12-2 to the V-phase current conversion circuit 53 that constitutes the above-mentioned detection unit 15. The V-phase current conversion circuit 53 includes, for example, an AD converter. The detection unit 15 in the V-phase current conversion circuit 53 detects the V-phase AC motor drive current flowing between the V-phase first wiring pattern 11-2 and the V-phase second wiring pattern 12-2 via the shunt resistors in the V-phase first resistor unit 13-2 and the V-phase second resistor unit 14-2, based on the potential difference ΔV [V] between the V-phase first potential detection point and the V-phase second potential detection point.

[0071] The W-phase wiring pattern 41 is electrically connected to a W-phase terminal (not shown) of the motor.

[0072] In the motor drive device 100, the current detection circuit 1 is disposed in the inverter main circuit 51 equipped with an intelligent power module. This inevitably means that many main circuit patterns (i.e., U-phase first wiring pattern 11-1, U-phase second wiring pattern 12-1, V-phase first wiring pattern 11-2, V-phase second wiring pattern 12-2, W-phase wiring pattern 41, positive side DC wiring pattern 42, and negative side DC wiring pattern 43) with various potentials are disposed around the current detection circuit 1. This imposes various constraints on the implementation of each main circuit pattern, such as ensuring sufficient insulation distance. Furthermore, from the viewpoint of noise reduction, it is preferable that the signal lines between each potential detection point and each AD converter in the U-phase current conversion circuit 52 and the V-phase current conversion circuit 53 be as short as possible. Furthermore, because an insulated AD converter is generally used and includes a main circuit side (primary side) and a digital data side (secondary side), various constraints are imposed on the implementation of each signal line and each main circuit pattern. Given these various constraints, in order to implement the signal lines and main circuit patterns as widely dispersed as possible while taking into consideration the heat generated by the shunt resistors of U-phase first resistor portion 13-1, U-phase second resistor portion 14-1, V-phase first resistor portion 13-2, and V-phase second resistor portion 14-2, U-phase first wiring pattern 11-1, U-phase second wiring pattern 12-1, V-phase first wiring pattern 11-2, and V-phase second wiring pattern 12-2 are provided so as to satisfy the resistance requirements of the first or second form described above.

[0073] <Examples not covered by the embodiment> Next, an example of the arrangement of shunt resistors and wiring patterns that is not covered by an embodiment of the present disclosure will be described with reference to FIGS. 5 and 6. FIG.

[0074] Fig. 5 is a diagram showing a current detection circuit in which a shunt resistor is provided between two wiring patterns that do not have parallel regions in the same wiring direction, and Fig. 6 is a circuit diagram showing an equivalent circuit of the current detection circuit shown in Fig. 5.

[0075] 5 and 6 is outside the scope of an embodiment of the present disclosure for the following reason.

[0076] In the current detection circuit 101, a wiring pattern 111 electrically connected to a power element (not shown) provided in a power conversion device (not shown) and a wiring pattern 112 electrically connected to a terminal of a motor (not shown) driven by the power conversion device do not have a parallel region in the same wiring direction. That is, the wiring patterns 111 and 112 are arranged on approximately the same line. An end of the wiring pattern 111 and an end of the wiring pattern 112 are electrically connected by a shunt resistor 113 and a shunt resistor 114 connected in parallel to each other. More specifically, the end of the wiring pattern 111 is electrically connected to a first terminal C1 of the shunt resistor 113 and a first terminal D1 of the shunt resistor 114. The end of the wiring pattern 112 is electrically connected to a second terminal C2 of the shunt resistor 113 and a second terminal D2 of the shunt resistor 114.

[0077] In the powering state, as shown by the bold arrow in Fig. 5, the motor drive current (powering current) flowing from the power element along the wiring direction (longitudinal direction) on wiring pattern 111 flows through shunt resistors 113 and 114, and then flows along the wiring direction (longitudinal direction) on wiring pattern 112 toward the motor terminals. In the regenerative state, the motor drive current (regenerative current) flowing from the motor terminals along the wiring direction (longitudinal direction) on wiring pattern 112 in the opposite direction to the bold arrow in Fig. 5 flows through shunt resistors 113 and 114, and then flows along the wiring direction (longitudinal direction) on wiring pattern 111 toward the power element.

[0078] A first potential detection point Q1 is provided on the wiring pattern 111 between the first terminal C1 of the shunt resistor 113 and the first terminal D1 of the shunt resistor 114. In addition, a second potential detection point Q2 is provided on the wiring pattern 112 between the second terminal C2 of the shunt resistor 113 and the second terminal D2 of the shunt resistor 114.

[0079] Signal lines are wired from the first potential detection point Q1 and the second potential detection point Q2 to the detection unit 115. The detection unit 115 detects the motor drive current flowing between the wiring pattern 111 and the wiring pattern 112 via the shunt resistors 113 and 114, based on the potential difference ΔV [V] between the first potential detection point Q1 and the second potential detection point Q2.

[0080] The resistance value of a resistance component 131 between the first terminal C1 of the shunt resistor 113 and the first potential detecting point Q1 on the wiring pattern 111 is set to R1 [Ω]. The resistance value of a resistance component 132 between the first potential detecting point Q1 and the first terminal D1 of the shunt resistor 114 on the wiring pattern 111 is set to R2 [Ω]. The resistance value of a resistance component 133 between the second terminal C2 of the shunt resistor 113 and the second potential detecting point Q2 on the wiring pattern 112 is set to R3 [Ω]. The resistance value of a resistance component 134 between the second potential detecting point Q2 and the second terminal D2 of the shunt resistor 114 on the wiring pattern 112 is set to R4 [Ω]. The resistance values of the shunt resistors 113 and 114 are set to R s The path of the current flowing from wiring pattern 111 through shunt resistor 113 to wiring pattern 112 is a series circuit consisting of resistance component 131, shunt resistor 113, and resistance component 133. Similarly, the path of the current flowing from wiring pattern 111 through shunt resistor 114 to wiring pattern 112 is a series circuit consisting of resistance component 132, shunt resistor 114, and resistance component 134. Because these series circuits are connected in parallel with each other, the current detection circuit 1 shown in FIG. 5 can be expressed as an equivalent circuit as shown in FIG. 6.

[0081] When "R1=R2=R3=R4", the resistance value R of the combined resistance consisting of the series circuit consisting of the resistance component 131, the shunt resistor 113, and the resistance component 133 and the series circuit consisting of the resistance component 132, the shunt resistor 114, and the resistance component 134 is X [Ω] can be expressed as in Equation 13.

[0082]

number

[0083] At this time, the potential difference ΔV [V] between the first potential detection point Q1 and the second potential detection point Q2 is expressed as in Equation 14.

[0084]

number

[0085] As can be seen from Equation 14, the potential difference ΔV [V] between the first potential detection point Q1 and the second potential detection point Q2 includes the resistance components (e.g., R1) of the wiring patterns 111 and 112. Therefore, in the current detection circuit 101 in which the shunt resistors 113 and 114 are provided between the two wiring patterns 111 and 112 that do not have a parallel region in the same wiring direction as shown in FIG. 5, the current detection circuit 101 is affected by the resistance components of the wiring patterns 111 and 112 and is therefore outside the scope of one embodiment of the present disclosure.

[0086] <Method for adjusting the resistance values of the first wiring pattern and the second wiring pattern> Next, a method for adjusting the resistance values of the first wiring pattern 11 and the second wiring pattern 12 in an embodiment of the present disclosure will be described.

[0087] As described above, in one embodiment of the present disclosure, the first wiring pattern 11 and the second wiring pattern 12 are provided so as to satisfy the resistance requirements of the first or second form. The resistance values of the resistance components on the first wiring pattern 11 and the second wiring pattern 12 are determined by the distance between the terminals, the shapes of the first wiring pattern 11 and the second wiring pattern 12, and the materials of the first wiring pattern 11 and the second wiring pattern 12. Below, several methods for adjusting the resistance values of the first wiring pattern 11 and the second wiring pattern 12 are listed.

[0088] The first adjustment method involves providing the first wiring pattern 11 and the second wiring pattern 12 with the same shape and material in a region S where the wiring directions of the first wiring pattern 11 and the second wiring pattern 12 are substantially parallel during the manufacturing stage of the motor drive device, and then adjusting the distance between the first terminal A1 of the first resistor unit 13 and the first potential detection point T1, the distance between the first potential detection point T1 and the first terminal B1 of the second resistor unit 14, the distance between the second terminal A2 of the first resistor unit 13 and the second potential detection point T2, and the distance between the second potential detection point T2 and the second terminal B2 of the second resistor unit 14 to be substantially equal. In this case, it is preferable to set the center points on the end faces of each terminal and the center points on the end faces of each potential detection point as the start and end points for measuring the distances. Note that if the resistance requirements of the first or second embodiment cannot be met even after adopting the first adjustment method, any of the second to fourth adjustment methods described below may also be adopted.

[0089] The second adjustment method involves providing a notch for adjusting the resistance value in at least one of the first wiring pattern 11 and the second wiring pattern 12 in a region S where the wiring direction of the first wiring pattern 11 and the wiring direction of the second wiring pattern 12 are substantially parallel during the manufacturing stage of the motor drive device. FIG. 7 is a diagram illustrating a second resistance adjustment method for a motor drive device according to an embodiment of the present disclosure. The resistance values of the resistance components 31 to 34 are determined by the shapes of the first wiring pattern 11 and the second wiring pattern 12 in the region S where the wiring direction of the first wiring pattern 11 and the wiring direction of the second wiring pattern 12 are substantially parallel. When a notch is provided in the first wiring pattern 11 and / or the second wiring pattern 12, the current path on the wiring pattern is narrowed by the notch, thereby increasing the resistance value. The resistance value also varies depending on the size, shape, and number of the notches and the positions at which the notches are provided. Therefore, in the second adjustment method, the first wiring pattern 11 and / or the second wiring pattern 12 are designed and manufactured so that a cutout portion is provided on the first wiring pattern 11 and / or the second wiring pattern 12 so as to satisfy the resistance requirements of the first form or the second form. In the example shown in Fig. 7, as an example, a semicircular cutout portion 16-1 is provided on the first wiring pattern 11 near the second resistance portion 14, and a trapezoidal cutout portion 16-2 is provided on the second wiring pattern 12 near the first resistance portion 13.

[0090] The third adjustment method involves providing vias for adjusting the resistance value in at least one of the first wiring pattern 11 and the second wiring pattern 12 in a region S where the wiring directions of the first wiring pattern 11 and the second wiring pattern 12 are substantially parallel during the manufacturing stage of the motor drive device. FIG. 8 is a diagram illustrating the third adjustment method for the resistance value of a motor drive device according to an embodiment of the present disclosure. Similar to the cutouts in the second adjustment method, providing vias in the first wiring pattern 11 and / or the second wiring pattern 12 as in the third adjustment method narrows the current path on the wiring pattern by the amount of the vias, thereby increasing the resistance value. Furthermore, the resistance value varies depending on the size, shape, and number of vias, as well as the positions at which the vias are provided. Therefore, in the third adjustment method, the motor drive device is designed and manufactured so that vias are provided in the first wiring pattern 11 and / or the second wiring pattern 12 to satisfy the resistance requirements of the first or second embodiment. In the example shown in Figure 8, as an example, four vias 17 arranged in an L shape are provided on the first wiring pattern 11 near the first resistance portion 13, and three vias 17 arranged in a triangular shape are provided on the second wiring pattern 12 near the second resistance portion 14.

[0091] In the fourth adjustment method, the resistance value is adjusted by trimming at least one of the first wiring pattern 11 and the second wiring pattern 12 in a region S where the wiring directions of the first wiring pattern 11 and the second wiring pattern 12 are substantially parallel. FIG. 9 is a diagram illustrating a fourth adjustment method for the resistance value of a motor drive device according to an embodiment of the present disclosure. FIG. 10 is a circuit diagram illustrating an equivalent circuit of the current detection circuit shown in FIG. 9. Trimming is a process in which a resistor is cut with a laser while measuring it to achieve a target resistance value, or by repeatedly measuring the resistor and cutting it with a laser, and has the advantage of allowing fine adjustment of the resistance value. When trimming is performed on the first wiring pattern 11 and / or the second wiring pattern 12, which are resistors, the current path on the wiring pattern is narrowed by the amount of cutting, thereby increasing the resistance value. The resistance value also varies depending on the size, shape, and number of cuts made by trimming, as well as the locations at which the cuts are made. Trimming is performed as one of a series of steps in a shipping test for a completed motor drive device. During the shipping test, the difference between the motor drive current detected by the detection unit 15 in the current detection circuit 1 and the motor drive current detected by a first current detection device (not shown) for shipping tests, which is different from the detection unit 15, is measured, and trimming is performed based on the measurement result to obtain a desired resistance value. Measurements are performed each time trimming is performed, and trimming is repeated until the desired resistance value is obtained. For example, when the resistance values of each resistance component are measured during the shipping test for a completed motor drive device, as shown in FIG. 10, the resistance value of resistance component 31 is 0.08 mΩ, the resistance value of resistance component 32 is 0.08 mΩ, the resistance value of resistance component 33 is 0.04 mΩ (= the combined resistance value of resistance values R3 and R5), and the resistance value of resistance component 34 is 0.04 mΩ (= the combined resistance value of resistance values R4 and R6). To set the resistance value of the resistance component 33 at 0.08 mΩ (=resistance value R3), cut portions 19-1 and 19-2 corresponding to removing resistance value R5 are provided by trimming near the first resistance portion 13 on the second wiring pattern 12.In addition, in order to adjust the resistance value of the resistance component 34 to 0.08 mΩ (=resistance value R4), a cut portion 18 equivalent to removing resistance value R6 is provided by trimming near the second resistor portion 14 on the second wiring pattern 12.

[0092] <Current correction function in motor drive devices> By adjusting the resistance values of the first wiring pattern 11 and the second wiring pattern 12 using the first to fourth adjustment methods so as to satisfy the resistance requirements of the first or second form, it is possible to detect the motor drive current with high accuracy without being affected by the resistance component of the wiring pattern on which the current detection circuit 1 is provided. However, if a detection error in the motor drive current still occurs, a current correction function may be provided within the motor drive device.

[0093] FIG. 11 is a diagram illustrating a motor drive device having a current correction function according to an embodiment of the present disclosure.

[0094] The motor drive device 100 includes the current detection circuit 1, the power conversion device 2, a current conversion unit 21, a correction amount generation unit 22, a current conversion correction unit 23, and a host control unit 24.

[0095] The power conversion device 2 is an inverter that performs power conversion between DC power in a DC link (not shown) and AC power, which is drive power or regenerative power for the motor 3. The inverter is made up of a full-bridge circuit configured with power elements, each of which is made up of a diode and a switching element connected in antiparallel to the diode. The power element may be an intelligent power module (IPM), which is a power semiconductor element incorporating a drive circuit such as a MOSFET or an IGBT and a self-protection function. A rectifier (not shown) is electrically connected to the power conversion device 2 via the DC link. The rectifier converts AC power input from an AC power source into DC power and outputs it to the DC link, which is the DC output side.

[0096] The speed, torque, or rotor position of the motor 3 is controlled based on the motor drive current supplied from the power conversion device 2.

[0097] As described above, the current detection circuit 1 is provided on a power line connecting the first wiring pattern 11, which is electrically connected to a power element (not shown) provided in the power conversion device 2, and the second wiring pattern 12, which is electrically connected to the terminal of the motor 3 driven by the power conversion device 2. In the current detection circuit 1, an analog motor drive current is detected by the detection unit 15 based on the potential difference ΔV between the first potential detection point T1 provided on the first wiring pattern 11 and the second potential detection point T2 provided on the second wiring pattern 12, and the analog motor drive current is input to the current conversion unit 21.

[0098] Current conversion unit 21 converts the analog motor drive current detected by detection unit 15 into digital current data and outputs it. However, the digital current data output by current conversion unit 21 is corrected by current conversion correction unit 23 during normal operation of motor drive device 100, but is not corrected by current conversion correction unit 23 when correction amount generation unit 22 generates a correction amount.

[0099] Correction amount generator 22 generates a correction amount corresponding to the difference between the digital current data output by current converter 21 at a predetermined timing and the digital motor drive current detected at the predetermined timing by a second current detector (not shown) different from detector 15. Here, the "predetermined timing" is, for example, during shipping testing or maintenance of motor drive device 100. The correction amount generated by correction amount generator 22 during shipping testing or maintenance of motor drive device 100 is used by current conversion corrector 23 and current converter 21 during normal operation of motor drive device 100.

[0100] During normal operation of the motor drive device 100, the current conversion correction unit 23 controls the current conversion unit 21 to perform current conversion processing that takes into account the amount of correction.

[0101] During normal operation of motor drive device 100, current conversion unit 21 outputs digital current data corrected by current conversion correction unit 23.

[0102] The host control unit 24 executes various processes in the motor drive device 100 based on the digital current data output by the current conversion unit 21. For example, if the potential difference ΔV between the first potential detection point T1 and the second potential detection point T2 ranges from 0V to 5V, and the value of the current data (AD value) output by the current conversion unit 21 corresponding to this range ranges from 0 to 5000, the host control unit 24 can recognize that the motor drive current ranges from -100A to +100A.

[0103] As a modification, the current conversion correction unit 23 may be provided in the upper control unit 24, and the current conversion correction process may be executed in the upper control unit 24.

[0104] The motor drive device 100 includes an arithmetic processing unit (processor). Examples of arithmetic processing units include ICs, LSIs, CPUs, MPUs, and DSPs, and they may also include an AD converter. The motor drive device 100, which includes an arithmetic processing unit, is a functional module implemented by a computer program executed on the processor. For example, if the motor drive device 100 is implemented in the form of a computer program, the functions of the current conversion unit 21, the correction amount generation unit 22, the current conversion correction unit 23, and the upper control unit 24 can be realized by operating the arithmetic processing unit in accordance with the computer program. The computer program for executing the processing of the motor drive device 100 may be provided in the form of a computer-readable recording medium, such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. Alternatively, the motor drive device 100 may be implemented as a semiconductor integrated circuit into which a computer program for implementing the functions is written.

[0105] Although the preferred embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and changes can be made within the scope of the claims. [Explanation of symbols]

[0106] 1 Current detection circuit 2. Power conversion device 3 motors 11 First wiring pattern 11-1 U phase 1 wiring pattern 11-2 V phase 1 wiring pattern 12 Second wiring pattern 12-1 U phase second wiring pattern 12-2 V phase second wiring pattern 13 1st resistance section 13-1 U phase 1st resistance section 14 2nd resistance section 14-1 U phase 2nd resistor section 15 Detector 16-1, 16-2 Notch 17 Beer 18, 19-1, 19-2 Cutting points 21 Current conversion section 22 Correction amount generation section 23 Current conversion correction section 24 Upper control section 31, 32, 33, 34 Resistance components 41 W phase wiring pattern 42 Positive DC wiring pattern 43 Negative DC wiring pattern 51 Inverter main circuit 52 U-phase current conversion circuit 53 V-phase current conversion circuit 100 Motor drive device A1 First terminal of the first resistor section A2 Second terminal of the first resistor B1 First terminal of the second resistor B2 Second terminal of the second resistor section N Negative DC terminal P Positive DC terminal T1 First potential detection point T2 Second potential detection point UU phase AC terminal VV phase AC terminal w W-phase AC terminal

Claims

1. a first wiring pattern electrically connected to a power element provided in the power conversion device; a second wiring pattern electrically connected to a terminal of a motor driven by the power conversion device; a first resistor section and a second resistor section each having one shunt resistor or a plurality of shunt resistors connected in parallel, wherein, in a region where the wiring direction of the first wiring pattern and the wiring direction of the second wiring pattern are substantially parallel, a first terminal of the first resistor section is electrically connected to the first wiring pattern and a second terminal of the first resistor section is electrically connected to the second wiring pattern, a first terminal of the second resistor section is electrically connected to the first wiring pattern and a second terminal of the second resistor section is electrically connected to the second wiring pattern; a detection unit that detects a motor drive current flowing between the first wiring pattern and the second wiring pattern via the shunt resistor based on a potential difference between a first potential detection point provided on the first wiring pattern between the first terminal of the first resistor portion and the first terminal of the second resistor portion, and a second potential detection point provided on the second wiring pattern between the second terminal of the first resistor portion and the second terminal of the second resistor portion; Equipped with a resistance value between the first terminal of the first resistor portion and the first potential detection point on the first wiring pattern is approximately equal to a resistance value between the second terminal of the first resistor portion and the second potential detection point on the second wiring pattern, and a resistance value between the first potential detection point and the first terminal of the second resistor portion on the first wiring pattern is approximately equal to a resistance value between the second potential detection point and the first terminal of the second resistor portion on the second wiring pattern.

2. 2. The motor drive device according to claim 1, wherein the first wiring pattern and the second wiring pattern are provided so that a resistance value on the first wiring pattern between the first terminal of the first resistor and the first potential detection point, a resistance value on the first wiring pattern between the first potential detection point and the first terminal of the second resistor, a resistance value on the second wiring pattern between the second terminal of the first resistor and the second potential detection point, and a resistance value on the second wiring pattern between the second potential detection point and the second terminal of the second resistor are substantially equal.

3. 3. The motor drive device according to claim 1, wherein the first wiring pattern, the second wiring pattern, the first resistor portion, and the second resistor portion are provided on the same plane on a substrate.

4. 3. The motor drive device according to claim 1, wherein, in a region where the wiring direction of the first wiring pattern and the wiring direction of the second wiring pattern are substantially parallel, at least one of the first wiring pattern and the second wiring pattern has a notch for adjusting the resistance value.

5. 3. The motor drive device according to claim 1, wherein a via for adjusting the resistance value is provided in at least one of the first wiring pattern and the second wiring pattern within a region in which the wiring direction of the first wiring pattern and the wiring direction of the second wiring pattern are approximately parallel.

6. 3. The motor drive device according to claim 1, wherein the resistance value is adjusted by trimming at least one of the first wiring pattern and the second wiring pattern in a region in which the wiring direction of the first wiring pattern and the wiring direction of the second wiring pattern are substantially parallel.

7. 7. The motor drive device according to claim 6, wherein the trimming is performed so as to obtain the desired resistance value according to the difference between the motor drive current detected by the detection unit and the motor drive current detected by a first current detection device different from the detection unit.

8. 8. The motor drive device according to claim 7, wherein the trimming is performed at the time of a shipping test of the motor drive device.

9. a current conversion unit that converts the analog motor drive current detected by the detection unit into digital current data and outputs the digital current data; a correction amount generating unit that generates a correction amount according to a difference between the current data output by the current converting unit at a predetermined timing and the motor drive current detected by a second current detecting device different from the detecting unit at the predetermined timing; a current conversion correction unit that corrects the current data output by the current conversion unit based on the correction amount; The motor drive device according to claim 1 or 2, comprising:

10. 10. The motor drive device according to claim 9, wherein the predetermined timing is a shipping test of the motor drive device.

Images