JP2009210496A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor of non-contact detection for improving detection characteristics while achieving miniaturization and cost reduction. <P>SOLUTION: The current sensor is incorporated while sandwiching bus bars 7u-7w interposed in a detection object electric path into a printed wiring board 9, and in the printed wiring board 9, a conductor pattern 10 is formed so as to surround the bus bars 7u-7w by sandwiching the printed wiring board 9. A resistor 12 is provided on the way of the conductor pattern 10, and a current of the bus bars 7u-7w is detected by a voltage between terminals of the resistor 12 in non-contact. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a current sensor for non-contact detection of current in a load power supply path and the like, and more particularly to a novel configuration for improving detection characteristics while reducing size and cost.

  Conventionally, in a vehicle such as an electric vehicle (EV) or a hybrid vehicle (HEV), the inverter is controlled by detecting a current supplied from a power supply device inverter to a running motor.

  In many cases, the current (AC current, pulse current, DC current, etc.) of the power supply path for various loads such as the motor is detected in a non-contact manner by a current sensor using a Hall element that is a magnetic sensing element. (For example, see Patent Document 1).

  The conventional Hall element type current sensor is configured as shown in FIG. 6, and includes a bus bar 100 and a sensor body 200 that are inserted in a power supply path of the motor, for example. The sensor body 200 incorporates a magnetic core such as a ferrite core, a Hall element, a bias circuit thereof, and the like, and the bus bar 100 penetrates the hole 201 in the center.

  Then, the output voltage of the Hall element changes due to a change in the magnetic field lines of the magnetic core based on the current change of the bus bar 100, and the current flowing through the bus bar 100 by the Hall element output voltage, that is, the power supply path of the motor Non-contact detection of current and input current of the inverter that is the power source. Actually, the motor is a three-phase brushless motor or the like, and the current sensor has the above-described configuration of the bus bar 100 and the sensor body 200 for each phase of the motor and each input of the inverter, and the current of each phase is individually supplied. To detect.

In the non-contact detection type current sensor having such a configuration, for example, when a high voltage circuit of 200V to 300V of the inverter is used as a detection target circuit, the high voltage side and the low voltage side (control system side) are electrically connected. Therefore, it is possible to detect the current of the electric circuit to be detected by electrically isolating it. Therefore, it is superior in safety on the control system side than the contact detection type current sensor that directly detects the current on the high voltage side by a shunt resistor. In addition, a large component that can withstand high voltage and large current such as the shunt resistor is not required, and furthermore, no loss occurs on the measurement side (the high voltage side).
JP 2002-303642 (abstract, paragraph [0037], FIG. 3 etc.)

  As is clear from FIG. 6, the conventional non-contact detection type current sensor requires a sensor body 200 larger than the bus bar 100, and has a problem of being large and bulky. In addition, a Hall element and its bus bar circuit are required and expensive. Furthermore, there is a problem that the distance between the bus bar 100 and the main body case 200 is likely to change due to vibrations of the vehicle and the like, and the detection characteristics are likely to vary.

  An object of the present invention is to provide a non-contact detection type current sensor that improves detection characteristics while reducing size and cost.

  In order to achieve the above-described object, the current sensor of the present invention incorporates a bus bar inserted in a detection target electric circuit in a state of being sandwiched between printed wiring boards, and the printed wiring board sandwiches the printed wiring board. A conductor pattern is formed so as to surround the bus bar, a resistor is provided in the middle of the conductor pattern, and the current of the bus bar is detected in a non-contact manner by the voltage between the terminals of the resistor (claim 1).

  In the case of the current sensor of the present invention, the bus bar is incorporated in a printed wiring board (also referred to as a printed wiring board) in a through state, and the printed wiring board and the bus bar are integrated. In addition, since a conductor pattern is formed on the printed wiring board so as to form a coil surrounding the bus bar, a transformer with the bus bar as the primary side and the coil of the conductor pattern as the secondary side is formed in the printed wiring board. The magnetoelectric conversion structure is formed by the conductor pattern.

  When a current (primary side current) flows through the bus bar, a current (secondary side current) corresponding to the conductor pattern flows. At this time, the voltage between the terminals of the resistor provided in the middle of the conductor pattern changes according to the current of the conductor pattern, and the current of the detection target circuit is detected in a non-contact manner from the voltage between the terminals of the resistor.

  In this case, the bus bar is built in the printed wiring board, the printed wiring board and the bus bar are integrated, the conductor pattern is formed on the printed wiring board, and the resistor is also provided on the printed wiring board. There is no large part surrounding the bus bar like the main body 200, and it can be formed extremely small. In addition, there is an advantage that an assembling operation of parts is unnecessary.

  Moreover, since it is formed using a conductor pattern and an inexpensive resistor instead of an expensive Hall element or the like, it is extremely inexpensive.

  Furthermore, since the conductor pattern is formed on the printed wiring board and the resistor is also provided on the printed wiring board, there is almost no variation in detection characteristics due to vibration even in an environment with a lot of vibration such as a vehicle. The conversion characteristic of the structure is improved and the detection characteristic of the current sensor is improved.

  Accordingly, it is possible to provide a novel non-contact detection current sensor which has been improved in detection characteristics while reducing the size and cost. Note that the number of turns and the wire diameter on the secondary side of the transformer can be easily adjusted by changing the number and thickness of the conductor patterns, and there is an advantage that the degree of freedom in design and manufacturing is increased.

  Next, in order to describe the present invention in more detail, one embodiment will be described in detail with reference to FIGS.

  This embodiment shows a case where the present invention is applied to a current sensor of a vehicle such as an electric vehicle (EV) or a hybrid vehicle (HEV). FIG. 1 is a schematic diagram of the vehicle 1 and FIG. The structure of a feed path part is shown, (a) is a top view, (b) is the front view. 3 is an enlarged schematic view of the current sensor 3 of FIG. 2, and FIG. 4 is a partial cross-sectional view thereof. FIG. 5 is a circuit connection diagram of the inverter 4 of FIG.

  As shown in FIG. 1, a vehicle 1 is equipped with a traveling battery 4 made of, for example, a hydrogen nickel battery, and the output of the battery 4 is fed to an inverter 5.

  For example, as shown in FIG. 5, the inverter 5 is formed of a well-known three-phase full bridge circuit of a plurality of switching semiconductors Q formed by IGBTs and power FETs, and each of U, V, and W based on inverter control described later. By switching the phase switching semiconductor Q, the output of the three-phase U, V, W having a high voltage of 300 V is supplied to the motor 2 via the current sensor 3. In FIG. 5, 5p and 5n are positive and negative DC terminals, 5u, 5v and 5w are three-phase output terminals, and g is a gate terminal of each switching semiconductor Q.

  As shown in FIGS. 2A and 2B, the input side of the battery 4 and the inverter 5 is connected by a positive bus bar 6a and a negative bus bar 6b, and the output side of the inverter 5 is a current sensor 3. Are connected to one end of the three-phase bus bars 7u, 7v, 7w. The other ends of the bus bars 7u, 7v, 7w are connected to the motor 2 via terminal blocks or the like. Further, as shown in FIG. 2B, the current sensor 3 is fixed to the upper surface of the chassis 8 having an appropriate height by bolting or the like.

  The bus bars 7u to 7W of each phase of the current sensor 3 inserted in the three-phase power feeding path of the motor 2 that is the detection target electric path are sandwiched by the printed wiring board 9 in a state of being arranged on the printed wiring board 9 at an appropriate interval. Built in.

  The printed wiring board 9 is a so-called double-sided board. As shown in FIGS. 3 and 4, for example, at the center of the surface of the printed wiring board 9, each phase conductor having an appropriate length and thickness crossing each of the bus bars 7 u to 7 W. A pattern 10 is formed on both sides. Further, the end portions of the conductive patterns 10 on both sides are electrically connected by, for example, through holes (including via holes) 11 of the printed wiring board 9.

  Therefore, as is clear from FIG. 4, the conductor pattern 10 is formed on the printed wiring board 9 so as to surround each of the bus bars 7 u to 7 w with the printed wiring board 9 interposed therebetween. The conductor pattern 10 and the through holes 11 at both ends thereof form a loop coil corresponding to the core through which the bus bars 7u to 7w of each phase pass.

  At this time, each phase bus bar 7u to 7w and the loop coil are used in the printed wiring board 9, and each phase transformer having the bus bar 7u to 7w as the primary side and the loop coil as the secondary side is provided. When a current (primary side current) flows through each of the bus bars 7u to 7w, a current corresponding to the primary side current (secondary side current) flows through the conductor pattern 10 of each phase due to the magnetoelectric conversion of the transformer. .

  Further, for example, a resistor 12 that is a chip component is provided in the middle of the conductor pattern 10 of each phase on the surface side of the printed wiring board 9, and the secondary side current of the loop-shaped coil of each phase is the resistance of each phase. By flowing the body 12, a voltage (inter-terminal voltage) of, for example, about several hundred mV corresponding to the current of each of the bus bars 7u to 7w is generated between the terminals of the resistor 12 of each phase. Thus, the current of each phase of the motor 2 is detected in a non-contact manner.

  The conductor pattern 10 of each phase on the substrate surface side is formed by branching a lead line pattern 13 from both terminal portions of the resistor 12, and the voltage between the terminals of the resistor 12 of each phase is the lead line pattern 13. And is taken into an inverter-controlled ECU 14 having a chip IC configuration provided on the printed wiring board 9. The ECU 14 performs microcomputer feedback control (software control) based on the voltage across the terminals of the resistors 12 of each phase, forms inverter control signals for each phase, and these inverter control signals are shown in FIG. The signal is supplied to the gate g of the switching semiconductor Q of each phase of the inverter 5 through the control signal cable 15.

  The bus bars 7u to 7w are built into the printed wiring board 9 by, for example, pressing the bus bars 7u to 7w into the printed wiring board 9 before curing in the manufacturing process of the printed wiring board 9. In addition, the conductor pattern 10 and the lead line pattern 13 are, for example, copper patterns, and are formed together with other electrodes and wiring patterns of the printed wiring board 9 by a pattern forming process of the printed wiring board 9. Moreover, the resistor 12 and ECU14 are mounted in the printed wiring board 9 by the automatic insertion by the surface mounting process of the printed wiring board 9, for example.

  As described above, in the case of the embodiment, the magnetoelectric conversion structure of the transformer of each phase formed in the printed wiring board 9 is formed by the conductor pattern 10 of each phase and provided in the middle of the conductor pattern 10. The current in the power supply path (detection target circuit) of the motor 2 is detected in a non-contact manner from the voltage between the terminals of the resistor 12.

  In this case, the bus bars 7u to 7w are incorporated in the printed wiring board 9, the printed wiring board 9 and the bus bars 7u to 7w are integrated, and the conductor pattern 10 of each phase is formed on the printed wiring board 9, and the resistor 12 Is also provided on the printed wiring board, so that it can be formed extremely small. Moreover, almost no assembly work or the like is required.

  Further, since the conductive pattern 10 and the inexpensive resistor 12 are used instead of the expensive Hall element or the like, it is extremely inexpensive.

  Furthermore, since the conductor pattern 10 is formed on the printed wiring board 9 and the resistor 12 is also provided on the printed wiring board 12, there is almost no variation in detection characteristics due to vibration of the vehicle 1 and the conversion characteristics of the magnetoelectric conversion structure are improved. Thus, the detection characteristics of the current sensor 3 are improved.

  Accordingly, it is possible to provide a novel non-contact detection type current sensor 3 which has been improved in detection characteristics while reducing size and cost. The wire diameter and the number of turns of the loop coil can be easily adjusted by changing the width of the conductor pattern 10 of each phase or by forming a plurality of conductor patterns 10 of each phase. There is also an advantage that the degree of freedom is increased.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, in the above-described embodiment, the detection target electric circuit Is a three-phase circuit, and in order to detect a three-phase current, the printed wiring board 9 includes three bus bars 7u to 7w, and a conductor pattern 10 is formed for each bus bar 7u to 7w. 3) The resistor 12 is provided. When the detection target circuit is a single-phase circuit, a single-phase bus bar is built in the printed wiring board 9, and a conductor pattern or the like is formed on the bus bar. One resistor 12 may be provided. If the circuit to be detected is a multi-phase circuit from three phases, a bus bar for each phase is built in the printed wiring board 9 to form a conductor pattern corresponding to the number of bus bars, and a resistor 12 is provided for each phase. That's fine. Furthermore, the current sensor of the present invention may be provided between the battery 4 and the inverter 5 to detect the input current of the inverter 5 in a non-contact manner. The present invention can also be applied to the detection of the current of a portion to be detected (anywhere) other than the phase current of the motor 2 such as the input current of the inverter 5. A bus bar may be incorporated in a printed wiring board to form a conductor pattern, and a resistor may be provided for each phase.

  Next, the printed wiring board 9 may be a so-called single-sided board or a flexible board. For example, in the case of a single-sided board, the conductor pattern 10 is formed on the wiring pattern forming surface (for example, the back surface) and the component mounting surface (for example, the front surface) ) And the like, and a jumper wire may be mounted instead of the conductor pattern 10 at a position corresponding to the conductor pattern 10 on the component mounting surface.

  The conductor pattern 10 and the like may be various conductor patterns other than a copper pattern such as an aluminum pattern, and any component may be mounted on the printed wiring board 9.

  The current sensor of the present invention may have any current magnitude in the detection target circuit, and the present invention can be applied to electric vehicles (EV), hybrid vehicles (HEV), fuel cell vehicles (FCV), etc. It can be applied to non-contact detection of various currents of a vehicle. Furthermore, the present invention can be applied not only to vehicles but also to non-contact detection type current sensors such as various machines and devices.

1 is a schematic diagram of a vehicle to which an embodiment of the present invention is applied. The structure of the electric power feeding path part of the motor for driving | running | working of FIG. 1 is shown, (a) is a top view, (b) is the front view. FIG. 3 is an enlarged schematic diagram of the current sensor 3 of FIG. 2. FIG. 4 is a partial cross-sectional view of FIG. 3. FIG. 2 is a circuit connection diagram of the inverter of FIG. 1. It is a perspective view of a prior art example.

Explanation of symbols

7u-7w Bus bar 9 Printed wiring board 10 Conductor pattern 12 Resistor

Claims (1)

Built-in bus bar inserted in the printed circuit board, inserted into the detection target circuit,
On the printed wiring board, a conductor pattern is formed so as to surround the bus bar with the printed wiring board interposed therebetween,
A resistor is provided in the middle of the conductor pattern,
A current sensor, wherein the current of the bus bar is detected in a non-contact manner by a voltage between terminals of the resistor.

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