JP2011226886A - Current detection resistor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current detection resistor module that allows accurate current detection without deteriorating the detection accuracy even when a load resistance is reduced.SOLUTION: A current detection resistor module 100 comprises: a low resistance substrate 120 of a current detection resistor R0 with a load resistance value equal to or less than 10 mΩ; a feedback resistor block 150 having built-in feedback resistors R1 and R2 for determining the amplification factor of a non-inverting amplifier; and an operational amplifier 160 having the non-inverting amplifier for amplifying a voltage generated by the current flow in the current detection resistor R0. In the feedback resistors R1 and R2, the feedback resistance ratio is adjusted so as to eliminate an error of the current detection resistor. The feedback resistance ratio is adjusted by trimming the feedback resistors R1 and R2. That is, high accuracy is achieved by trimming the feedback constant of an amplifier circuit to adjust the amplification factor of the non-inverting amplifier according to the error of a resistance value in the current detection resistor having a low resistance value.

Description

  The present invention relates to a current detection resistor module that detects the current of a wide range of electrical and electronic devices such as portable devices, automobiles that require large current control, and various inverter circuits.

  There are three general current detection methods: a current transformer method, a Hall element method, and a resistance method. In the current transformer method, a magnetic force generated by a current flowing in a current circuit is detected using a transformer. In the Hall element method, the magnetic force generated by the current flowing in the current circuit is detected using the Hall element. In the resistance method, a current detection resistor is connected in series to a current circuit, and a voltage generated by a current flowing through the detection resistor is detected.

  Methods for detecting magnetic force, such as the current transformer method and the Hall element method, are easily affected by a natural magnetic field, and are likely to vary due to a change in positional relationship. In addition, it is difficult to achieve high accuracy and the price is generally high.

  The resistance method operates at high speed with higher accuracy than the current transformer method and the Hall element method. In general, the price is low. However, since the current detection resistor acts as a loss, it is necessary to set the resistance value to a very small value. Also, the voltage drop that occurs is a very small voltage value. In order to A / D convert such a small voltage drop, it is necessary to amplify the voltage once using an operational amplifier or the like.

  In the resistance method, a current detection resistor is connected in series to the current detection circuit, so that a phenomenon occurs in which power is consumed and heat is generated. The power consumption and heat generation are proportional to the resistance value of the current detection resistor. For example, when a current of 10 A (ampere) is detected using a current detection resistor having a resistance value of 1Ω, a voltage of 1 volt is generated at both ends of the current detection resistor. In the current detection resistor having a resistance value of 1Ω, power consumption and heat generation of 10 A × 10 A × 1Ω = 100 W actually occur for current detection. This power consumption and heat generation are all energy losses.

  Since the power consumption and the heat generation amount are proportional to the resistance value, it is effective to reduce the resistance value in order to suppress power consumption and heat generation by the resistance method.

  When the current of 10 A is detected by the current detection resistor having a resistance value of 1Ω, the power consumption is 10A × 10A × 1Ω = 100 W. However, when detecting with a current detection resistor having a resistance value of 0.01Ω, the power consumption is reduced to 10A × 10A × 0.01Ω = 1 W, and the energy loss due to the power consumption is reduced to one hundredth.

  FIG. 1 is a diagram showing a change in power consumption when the current is kept constant at 10 A and the resistance value is changed. As shown in FIG. 1A, power consumption is proportional to the resistance value of the current detection resistor. As shown in FIG. 1B, when the resistance value decreases, the power consumption is reduced in proportion to the resistance value.

  In the resistance method, the power consumption decreases as the resistance value of the current detection resistor is lowered. However, the smaller the resistance value, the greater the influence of the conductor resistance of the terminal and the measurement error, and the higher accuracy becomes difficult. For example, when the conductor resistance of the terminal is 1 mΩ, 1 mΩ / 1Ω = 0.1% when the entire detection resistor is 1Ω. When the entire current detection resistor is 10 milliΩ, 1 mΩ / 10 mΩ = 10%, and the influence of the conductor resistance becomes large. Since this affects the finishing accuracy, the smaller the resistance value, the more difficult it is to manufacture and measure, and as a result, it becomes difficult to detect the current accurately.

  FIG. 2 is a diagram showing the ratio of the influence for each resistance value when the conductor resistance of the terminal is constant. As shown in FIG. 2A, the proportion of the conductor is inversely proportional to the magnitude of the resistance value of the current detection resistor. As shown in FIG. 2B, the smaller the resistance value, the greater the proportion of conductors, and the more easily the accuracy is affected.

  Resistive current detection is suitable for high accuracy and high speed. However, since it is connected in series with the current circuit, power is consumed for detection and heat is generated. Electricity consumption results in energy loss, and heat generation is accompanied by dangers such as equipment deterioration and fire. In order to prevent power consumption and heat generation by the resistance method, it is effective to lower the resistance value of the current detection resistor. However, as described above, decreasing the resistance value makes it difficult to achieve high accuracy, and the superiority of the resistance method is lost.

  Since the current detection resistor is selected to have a low resistance value in order to reduce the load, the voltage across the resistor is generally amplified. The current detection circuit combines a current detection resistor, an amplifier, and a feedback resistor that controls the amplification factor. In this case, the current detection accuracy is obtained by adding the error of the current detection resistor and the error of the feedback resistor.

  Patent Document 1 describes a current-voltage conversion circuit that cancels an offset voltage of an operational amplifier and can detect a small current. The current-voltage conversion circuit described in Patent Document 1 includes a detection resistor Rdet, an amplifier circuit including a first operational amplifier, and an offset adjustment current source including a third resistor R3 and a fourth resistor R4 that can be trimmed. The offset adjustment current source causes the offset adjustment current Iadj, whose current value is controlled by adjusting the resistance values of the third resistor R3 and the fourth resistor R4 that can be trimmed, to flow through the offset resistor Rofs of the amplifier circuit. The offset adjustment voltage Vofs is generated.

  Patent Document 2 describes a current detection circuit capable of adjusting the detection of the direction and absolute value of the current flowing through the current detection resistor to a desired direction and current value. A current detection circuit described in Patent Document 1 includes a current detection resistor, a voltage comparison circuit, and a voltage dividing circuit including at least one trimmable resistor connected to the current detection resistor. Monolithic except for resistors.

JP 2007-27895 A Japanese Patent Laid-Open No. 10-282158

  However, in the current detection by the conventional resistance method, there is a limit to reducing the resistance value of the current detection resistor while maintaining accuracy, and the problems of power consumption and heat generation still remain.

  The current-voltage conversion circuit described in Patent Document 1 controls the offset adjustment voltage of an operational amplifier by adjusting the resistance values of the third resistor R3 and the fourth resistor R4 that can be trimmed, It is not a technology to reduce the resistance value of

  The current detection circuit described in Patent Document 2 freely adjusts the absolute value and direction of the detected current even if there is a large offset voltage in the voltage comparison circuit by trimming the voltage dividing resistor of the voltage dividing circuit. However, this is not a technique for reducing the resistance value of the current detection resistor.

  In order to suppress energy loss and heat generation due to power consumption, it is necessary to reduce the resistance value for current detection. By reducing the resistance value for current detection, it becomes difficult to ensure the accuracy of the resistance value, and it becomes difficult to increase the accuracy. Conventionally, a technique for reducing the resistance value itself of the current detection resistor has not been provided.

  An object of the present invention is to provide a current detection resistor module capable of highly accurate current detection without reducing detection accuracy even when load resistance is reduced.

  The current detection resistor module of the present invention includes a substrate, a current detection resistor disposed on the substrate and detecting a current having a load resistance value of 10 mΩ or less, and the current detection resistor module disposed on the substrate, And an attachment portion to which an amplifier for amplifying a voltage generated by a current flowing through the current detection resistor can be attached; and an output voltage of the amplifier disposed on the substrate and electrically connected to the attachment portion. Is divided by a first resistor and a second resistor, a connection point between the first resistor and the second resistor is fed back to the input terminal of the amplifier, and the amplification factor of the amplifier is determined. A feedback resistor composed of a resistor, and the feedback resistor has a configuration in which a feedback resistance ratio between the first resistor and the second resistor is adjusted so as to eliminate an error of the current detection resistor.

  The current detection resistor module of the present invention includes a substrate, a current detection resistor that is disposed on the substrate and detects a current having a load resistance value of 10 mΩ or less, and is disposed on the substrate and flows through the current detection resistor. An amplifier for amplifying a voltage generated by a current; and disposed on the substrate; the output voltage of the amplifier is divided by a first resistor and a second resistor; and a connection point between the first resistor and the second resistor is A feedback resistor composed of the first and second resistors that feed back to the input terminal of the amplifier and determine the amplification factor of the amplifier, and the feedback resistor eliminates the error of the current detection resistor. A configuration is adopted in which the feedback resistance ratio between one resistor and the second resistor is adjusted.

  According to the present invention, by adjusting the feedback resistance ratio so as to eliminate the error of the current detection resistor, the gain is adjusted according to the error of the resistance value of the current detection resistor, thereby realizing high accuracy. Thereby, highly accurate current detection using a low resistance value with little energy loss can be realized.

The figure which shows the change of power consumption when the electric current is fixed at 10A and the resistance value is changed. The figure which shows the ratio of the influence for every resistance value when the conductor resistance of the terminal is constant The circuit diagram which shows the structural example of the current detection circuit by the non-inverting amplifier circuit of the principle description of this invention The figure which shows the relationship between the accuracy of the current detection resistance and the feedback resistance ratio and the current detection accuracy in the current detection circuit of FIG. The perspective view which shows the structure of the electric current detection resistance module which concerns on Embodiment 1 of this invention. Exploded perspective view of the current detection resistor module according to Embodiment 1 above The figure which shows the structure of the current detection resistance module which concerns on the said Embodiment 1. FIG. Circuit diagram for explaining trimming of the current detection resistor module according to the first embodiment. Flowchart of trimming control of current detection resistor module according to Embodiment 1 above The flowchart which shows the process of the trimming control signal generator of the current detection resistance module which concerns on the said Embodiment 1. FIG. The figure which shows the electric current detection error of the electric current detection resistance module which concerns on the said Embodiment 1. FIG. The figure which compares and shows the detection resistance value of the combination A and B of FIG. 11, and the detection error of a feedback resistance ratio The perspective view which shows the structure of the current detection resistance module which concerns on Embodiment 2 of this invention. Exploded perspective view of the current detection resistor module according to the second embodiment The figure which shows the structure of the current detection resistance module which concerns on the said Embodiment 2. FIG. Circuit diagram for explaining trimming of the current detection resistor module according to the second embodiment. Circuit diagram of current detection resistor module according to Embodiment 3 of the present invention The figure which shows the electric current detection error of the electric current detection resistance module which concerns on the said Embodiment 3.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Principle explanation)
The basic concept of the present invention will be described.

  The present invention realizes a current detection resistor module of a current detection resistor having a very small resistance value.

  The present inventor pays attention to the relationship between the accuracy of the current detection resistor and feedback resistance ratio of the current detection circuit and the current detection accuracy, and the current detection accuracy is determined by the error of the current detection resistor and the ratio of the feedback resistor. I found out.

  FIG. 3 is a circuit diagram showing a configuration example of a current detection circuit using a non-inverting amplifier circuit.

  As shown in FIG. 3, the current detection circuit 10 is a non-inverting amplifier circuit including a current detection resistor R0, an operational amplifier 11, and feedback resistors R1 and R2.

  A current Iin flows through the current detection resistor R0, and a voltage V0 is generated at both ends.

  The operational amplifier 11 has a positive input terminal connected to the input terminal side, a negative input terminal connected to a connection point between the resistor R1 and the resistor R2, and outputs the detection voltage Vout of the current detection circuit 10 from the output terminal. The operational amplifier 11 constitutes a non-inverting amplifier that outputs an output voltage having the same phase as the input voltage.

  The feedback resistors R1 and R2 divide the output voltage of the operational amplifier 11 by the resistors R1 and R2. As shown in FIG. 3, when the operational amplifier 11 is a non-inverting amplifier, the output terminal of the operational amplifier 11 is connected to the ground via the feedback resistors R1 and R2, and the negative input terminal of the operational amplifier 11 is the resistor R1. And the resistor R2.

  Although not shown, when the operational amplifier 11 is an inverting amplifier, the positive input terminal of the inverting amplifier is connected to the ground, and the output terminal of the inverting amplifier is input via feedback resistors R1 and R2. The negative input terminal of the inverting amplifier is connected to the connection point of the resistors R1 and R2.

  As shown in FIG. 3, when a current I flows through the current detection resistor R0, a voltage V1 of current × detection resistance value is generated between the terminals of the current detection resistor R0. This voltage V1 is amplified by the operational amplifier 11. The amplification factor X of the operational amplifier 11 is determined by the ratio of the feedback resistors R1 and R2.

  The amplification factor X is (1 + R2 / R1). For example, the amplification factor X in the case of R1 = 9 kΩ and R2 = 1 kΩ is 10 times (1 + 9 kΩ / 1 kΩ).

  When the current detection resistor R0 is 1 mΩ and the current I flows from the input terminal at 10 A, the voltage V0 generated at both ends of the current detection resistor R0 is 10 A × 1 mΩ = 10 mV. The operational amplifier 11 amplifies the voltage V0 10 times, and the voltage V1 output from the output terminal Vout becomes 100 mV.

  The current detection accuracy of the current detection circuit 10 is determined by the accuracy of the current detection resistor that provides the current detection resistor R0 and the ratio accuracy of the feedback resistors R1 and R2 of the operational amplifier 11.

  FIG. 4 is a diagram showing the relationship between the accuracy of the current detection resistor and feedback resistance ratio and the current detection accuracy in the current detection circuit 10 using the non-inverting amplifier circuit of FIG.

  As shown in FIG. 4, it can be seen that the current detection accuracy is determined by the error of the current detection resistance and the ratio of the feedback resistance. It can also be seen that the accuracy is maintained if the error of the current detection resistor and the error of the feedback resistance ratio are in a direction to cancel each other. This also works for circuits using other amplifiers that utilize feedback resistors.

  As shown in FIG. 4, in the current detection circuit 11 of FIG. 3, when the flowing current is constant, the relationship between the error of the current detection resistor R0 and the output voltage error is proportional. When the error of the current detection resistor R0 is + 1%, the output voltage error is also + 1%. When the current detection resistor R0 is constant, the relationship between the feedback resistance ratio error and the output error is also proportional, and when the feedback resistance ratio error is + 1%, the output voltage error is also + 1%. From these relationships, it is understood that the accuracy of the output voltage is determined by the error of the current detection resistor R0 and the errors of the feedback resistors R1 and R2, and the two errors influence each other.

  The present inventor pays attention to the relationship between the accuracy of the current detection resistor and feedback resistance ratio of the current detection circuit and the current detection accuracy, and the current detection accuracy is determined by the error of the current detection resistor and the ratio of the feedback resistor. I found out. That is, the error of the current detection resistor and the error of the ratio of the feedback resistor have a certain correlation, and the two errors are regarded as information linked to each other. In addition, an error in the ratio of the feedback resistance corresponding to the error in the current detection resistor is absorbed by adjusting the feedback resistance ratio. Adjustment of the feedback resistance ratio is performed by trimming the feedback resistance. Incidentally, although there has been a strong demand for reducing the resistance value of the current detection resistor, no means for realizing it has been provided.

  The present invention absorbs the error of the current detection resistor R0 by adjusting the feedback resistance ratio. That is, the present invention corrects the error of the current detection resistor R0 by adjusting the resistance ratio of the feedback resistors R1 and R2. The feedback resistance ratio is adjusted by trimming the feedback resistors R1 and R2.

  In the present invention, the combination of the current detection resistor R0, the amplifier and the feedback resistor is formed in advance, the output value is detected, the ratio of the feedback resistors is trimmed, and the adjustment is made so as to obtain a constant output. The feedback resistors R1 and R2 are trimmed for adjustment with respect to the error of the current detection resistor R0. Since the current detection resistance R0 error is absorbed by adjusting the feedback resistance ratio, a current detection resistance module having a very small resistance value can be realized.

  Here, since the error of the current detection resistor R0 can be absorbed by adjusting the ratio of the feedback resistors, the accuracy of the current detection resistor R0 is not required. Therefore, even if the resistance value of the detection resistor is small and the accuracy is not high, the necessary detection accuracy can be ensured by adjusting the feedback resistor. In particular, even when the value of the current detection resistor R0 is small and it is difficult to manufacture a highly accurate detection resistor, the error of the current detection resistor R0 is corrected by adjusting the ratio of the feedback resistors, thereby realizing a highly accurate current detection resistor module. Can do.

(Embodiment 1)
The first embodiment is an example applied to a current detection resistor module including an operational amplifier.

  5 to 7 are diagrams showing the configuration of the current detection resistor module according to Embodiment 1 of the present invention based on the above basic concept. FIG. 5 is a perspective view of the current detection resistor module, and FIG. 6 is an exploded perspective view of the current detection resistor module. 7A is a front view of the current detection resistor module, FIG. 7B is a back view of the current detection resistor module, FIG. 7C is a top view of the current detection resistor module, and FIG. 7D. These are side views of a current detection resistance module.

  As shown in FIGS. 5 to 7, the current detection resistor module 100 includes a glass epoxy substrate 110 and a low resistance substrate 120 disposed on one surface 110 a of the glass epoxy substrate 110.

  In the current detection resistor module 100, the other surface 110b of the glass epoxy substrate 110 is provided with the wiring 130 made of Cu or Cu alloy formed of a photoresist or the like, the wiring 130 other than the terminals, and the surface 110b of the glass epoxy substrate 110. And a solder resist 140 formed so as to cover it.

  The current detection resistor module 100 includes a feedback resistor block 150 including a feedback resistor and an operational amplifier 160.

  A through hole (Through Hole Via) 110 c for connecting the current terminals 121 and 122 (see FIG. 7B) at both ends of the low resistance substrate 120 to the corresponding nodes 131 and 132 of the wiring 130 is formed in the glass epoxy substrate 110. Is done. Similarly, a hole 140 a for allowing a current to flow through the current terminals 121 and 122 of the low resistance substrate 120 is formed in a corresponding portion of the solder resist 140.

  The low resistance substrate 120 is a current detection resistor having a load resistance value of 10 mΩ or less. Since the current detection resistor works as a loss, the resistance value is set to a very small value. In the present embodiment, the low resistance substrate 120 can have a resistance value of 10 mΩ or less.

  The feedback resistor block 150 has a feedback resistor that determines the amplification factor of the non-inverting amplifier that amplifies the voltage generated by the current flowing through the current detection resistor. This feedback resistor has a first resistor and a second resistor, and the feedback resistance ratio between the first resistor and the second resistor is adjusted so as to eliminate the error of the current detection resistor. The feedback resistance ratio is adjusted by trimming the first resistor or the second resistor. For example, when the second resistor is a resistor that can be trimmed, the second resistor is irradiated with a laser beam and adjusted to a desired resistance value by trimming to form a linear notch on the upper surface of the resistor.

  Hereinafter, trimming of the current detection resistor module 100 configured as described above will be described.

  FIG. 8 is a circuit diagram illustrating trimming of the current detection resistor module 100.

  As shown in FIG. 8, the current detection resistor module manufacturing system includes a current detection resistor module 100, a constant current power source 200, a trimming control signal generation device 210, and a trimming control device 220.

  The current detection resistor module 100 is a non-inverting amplifier circuit including a current detection resistor R0 of the low resistance substrate 120, an operational amplifier 160, and feedback resistors R1 and R2.

  The operational amplifier 160 has a positive input terminal connected to the current terminal (input terminal) 121 side of the current detection resistor module 100, a negative input terminal connected to a connection point between the resistor R 1 and the resistor R 2, and a current from the output terminal 133. The detection voltage Vout of the detection resistance module 100 is output.

  The current detection accuracy of the current detection resistor module 100 is determined by the accuracy of the current detection resistor that provides the current detection resistor R0 and the ratio accuracy of the feedback resistors R1 and R2 of the operational amplifier 160.

  A constant current power source 200 is connected to the current terminals 121 and 122 of the low resistance substrate 120 of the current detection resistor module 100. The constant current power source 200 supplies a constant current to the current terminals 121 and 122 of the low resistance substrate 120 of the current detection resistor module 100. As a result, the current Iin flows through the current detection resistor R0, and the voltage V0 is generated at both ends.

  The output terminal 133 of the current detection resistor module 100 is connected to the input terminal of the trimming control signal generator 210.

  The trimming control signal generation device 210 includes a feedback resistance ratio adjustment amount storage unit 211, a voltage detection unit 212, and a trimming control signal generation unit 213.

  The feedback resistance ratio adjustment amount storage unit 211 stores a feedback resistance ratio adjustment amount for absorbing the error of the current detection resistor R0 by adjusting the feedback resistance ratio. This will be specifically described. As shown in FIG. 4, the detection resistance error and the feedback resistance ratio error are in a substantially constant proportional relationship. If the feedback resistance ratio error is eliminated, the detection resistance error can be eliminated. The detection resistance error in the current detection resistor R0 is one of the reasons why the resistance value of the current detection resistor R0 cannot be reduced. In the present embodiment, the detection resistance error is absorbed by adjusting the feedback resistance ratio error. The adjustment amount for adjusting the feedback resistance ratio error is calculated in advance by simulation or the like, and this adjustment amount is stored in the feedback resistance ratio adjustment amount storage unit 211 as the feedback resistance ratio adjustment amount.

  The voltage detection unit 212 detects the voltage of the output terminal 133 of the current detection resistor module 100.

  The trimming control signal generation unit 213 generates a trimming control signal based on the voltage detected by the voltage detection unit 212 and the feedback resistance ratio adjustment amount read from the feedback resistance ratio adjustment amount storage unit 211. More specifically, the trimming control signal generation unit 213 compares the voltage detected by the voltage detection unit 212 with a set value, and when the voltage is out of the setting, the trimming control signal generation unit 213 reads the voltage from the feedback resistance ratio adjustment amount storage unit 211. In accordance with the feedback resistance ratio adjustment amount, a trimming control signal in which the voltage of the output terminal 133 of the current detection resistor module 100 falls within the set value is generated.

  The trimming control signal of the trimming control signal generation device 210 is connected to the input terminal of the trimming control device 220. The trimming control device 220 trims the feedback resistor R2 of the feedback resistor block 150 based on the trimming control signal from the trimming control signal generation device 210. This adjusts the feedback resistance ratio.

  Next, the trimming of the current detection resistor module 100 will be specifically described.

  As shown in FIG. 8, the constant current power source 200 is connected to the current terminals 121 and 122 of the current detection resistor module 100. Further, the input terminal of the trimming control signal generator 210 is connected to the output terminal 133 of the current detection resistor module 100. The trimming control device 220 stands by in a state where the feedback resistor R2 of the feedback resistor block 150 can be trimmed.

  The constant current power source 200 supplies a constant current to the current terminals 121 and 122 of the current detection resistor module 100.

  A current Iin flows through the current detection resistor R0 of the low resistance substrate 120 of the current detection resistor module 100, and a voltage V0 is generated at both ends.

  The operational amplifier 160 has a positive input terminal connected to the current terminal 121 side of the current detection resistor module 100, a negative input terminal connected to a connection point between the resistor R1 and the resistor R2, and the output terminal 133 to the current detection resistor module 100. Detection voltage Vout is output. Of the feedback resistors R1 and R2 of the operational amplifier 160, the feedback resistor R2 is a resistor that can be trimmed.

  The voltage value of the current detection resistor R0 × current Iin is input to the operational amplifier 160. The operational amplifier 160 amplifies the voltage value with the amplification factor of the feedback resistors R 1 and R 2 and outputs the amplified voltage value to the output terminal 133.

  The voltage detection unit 212 of the trimming control signal generation device 210 detects the voltage of the output terminal 133 of the current detection resistor module 100.

  The trimming control device 220 trims the feedback resistor R2 of the feedback resistor block 150 based on the trimming control signal from the trimming control signal generation device 210. For example, when performing trimming by irradiating the resistor of the feedback resistor R2 with laser light to form a linear notch in the resistor, the trimming control signal generator 210 sends a trimming control signal to the trimming controller 220. While being output, the trimming controller 220 performs trimming.

  By performing the trimming, the output of the current detection resistor module 100 changes. When the voltage at the output terminal 133 of the current detection resistor module 100 falls within the set range, the trimming control signal generator 210 stops outputting the trimming control signal. The trimming control device 220 stops trimming for the feedback resistor R2.

  FIG. 9 is a flowchart of trimming control of the current detection resistor module 100.

  When this flow starts, the constant current power supply 200 causes a constant current to flow through the current terminals 121 and 122 of the current detection resistor module 100.

  The operational amplifier 160 amplifies the voltage value of the current detection resistor R0 × current Iin with the amplification factor of the feedback resistors R1 and R2, and outputs the amplified value to the output terminal 133.

  In step S <b> 1, the trimming control signal generation device 210 detects the voltage of the output terminal 133 of the current detection resistor module 100.

  In step S2, the trimming control signal generator 210 compares the detected voltage with a set value, and outputs a trimming control signal if the voltage is outside the setting.

  In step S3, the trimming controller 220 trims the feedback resistor R2 of the feedback resistor block 150 based on the trimming control signal from the trimming control signal generator 210, and returns to step S1.

  When the voltage detected in step S <b> 2 falls within the set range, the trimming control signal generation device 210 stops outputting the trimming control signal.

  In step S4, the trimming control device 220 ends the trimming for the feedback resistor R2.

  This completes the adjustment of the current detection resistor module 100 that can obtain a constant voltage output at a constant current.

  FIG. 10 is a flowchart showing the processing of the trimming control signal generation device 210, and shows the details of the processing in step S1 of FIG.

  In step S <b> 11, the voltage detection unit 212 detects the voltage of the output terminal 133 of the current detection resistor module 100.

  In step S <b> 12, the trimming control signal generation unit 213 reads the corresponding feedback resistance ratio adjustment amount from the feedback resistance ratio adjustment amount storage unit 211 based on the voltage detected by the voltage detection unit 212.

  In step S13, the trimming control signal generation unit 213 generates a trimming control signal in which the voltage of the output terminal 133 of the current detection resistor module 100 falls within the set value, and returns to step S2 in FIG.

[Example]
Examples will be described below.

  The current detection resistor module 100 can ensure accuracy even if the resistance value of the current detection resistor R0 is lowered. For this reason, it is possible to reduce the energy consumed by the current detection resistor R0 and the amount of heat generated.

  For example, in the current detection resistor module 100 using the non-inverting amplifier circuit of FIG. 8, the constants of the current detection resistor R0 and the feedback resistors R1 and R2 when the current Iin is 10 A are as follows.

R0 = 10mΩ
R1 = 1kΩ
R2 = 9kΩ
The voltage V0 generated at both ends of the current detection resistor R0 is 10A × 10 mΩ = 100 mV.

  The current detection resistor module 100 using the non-inverting amplifier circuit amplifies the voltage V0 and outputs the voltage V1. The voltage V1 is 100 mV × (1 + 9 kΩ / 1 kΩ) = 1000 mV. The power consumption at the current detection resistor at this time is 10 A × 10 A × 10 mΩ = 1 W.

  In order to reduce the current detection resistor R0 and increase the amplification factor, each constant is as follows.

R1 = 0.1 mΩ (decrease from 10 mΩ)
R2 = 1kΩ (no change)
R3 = 999 kΩ (enlarge from 9 kΩ)
The voltage V0 generated at both ends of the current detection resistor R0 is 10A × 0.1 mΩ = 1 mV. The non-inverting amplifier circuit amplifies the voltage V0, and the voltage V1 is 1 mV × (1 + 999 kΩ / 1 kΩ) = 1000 mV.

  The power consumption at the current detection resistor R0 at this time is 10A × 10A × 0.1 mΩ = 0.01W.

  From the above, it can be seen that the output V1 becomes 1000 mV and the same output voltage can be obtained by changing the feedback resistance ratio even if the current detection resistor R0 is reduced from 10 mΩ to 0.1 mΩ. The power consumed by the current detection resistor R0 is 1 W when the current detection resistor is 10 mΩ. However, when the current detection resistor R0 is reduced to 0.1 mΩ, the power consumption is reduced to 0.01 W. Loss can be reduced to 1%.

  When the current detection resistor R0 is reduced, it is difficult to ensure the accuracy of the resistor due to an increase in the proportion of the conductor resistance and an increase in measurement difficulty. In the circuit of FIG. 8, since the current detection accuracy is proportional to the accuracy of the current detection resistor R0, if there is no error in the feedback resistance ratio accuracy, when the current detection resistor R0 is 10 mΩ, the accuracy of the current detection resistor R0 is When there is an error of ± 1%, the current detection accuracy is as high as ± 1%, similar to the current detection resistor R0. When the accuracy of the current detection resistor is reduced to ± 10% by reducing the current detection resistor R0 to 0.1 mΩ, the current detection accuracy is reduced to ± 10%.

  The current detection resistor module 100 compensates for the above accuracy reduction by trimming the feedback resistance ratio.

  When the current detection resistance is 0.1 mΩ and the resistance accuracy is + 10% in the circuit of FIG. 8, the output voltage is expressed by the following calculation formula.

V1 = (1 mV × 110%) × (1 + 999 kΩ / 1 kΩ)
= 1.1mV x 1000
= 1100 mV
It can be seen that an error of + 10% is output for 1000 mV.

  The current detection resistor module 100 absorbs the detection resistor error by trimming one of the feedback resistors (the feedback resistor R2 in FIG. 8) and adjusting the feedback resistance ratio.

  When the resistance value is increased by trimming from 1 kΩ of the feedback resistor R2 to 1.1001 kΩ, the following results.

V1 = (1 mV × 110%) × (1 + 999 kΩ / 1.1001 kΩ)
= 1.1 mV x 909.0993
= 1000.009mV
With respect to 1000 mV, adjustment is possible within a range of + 0.009% with almost no error.

  FIG. 11 is a diagram illustrating a current detection error of the current detection resistor module 100.

  It is confirmed that the feedback resistor can absorb the error of the current detection resistor R0. In the current detection resistor module 100 of FIG. 8, the combination of the resistance value of the current detection resistor R0 and the resistance value of the adjustment R1 was changed, and R1 was adjusted in the same way so that an output of 1 V per 10 A was obtained.

  FIG. 11A shows the combination A.

Current detection resistance value R0 = 1.13 mΩ
Feedback resistance R1 = 3.978 kΩ
Output before R1 adjustment 1.2V / 10A

  FIG. 11B shows the combination B.

Resistance value for current detection R0 = 0.27mΩ
Feedback resistance R1 = 0.71kΩ
Output before R1 adjustment 1.5V / 10A

  FIG. 12 is a diagram comparing the detection resistance values of the combinations A and B in FIG. 11 and the detection error of the feedback resistance ratio.

  FIG. 12 is a result of confirming the output at each current by adjusting the current to 10 V by passing a current of 10 A in both combinations A and B of FIG. As shown in FIG. 12, 1V / 10A output was obtained for both combinations A and B, and it was confirmed that the error of resistance value R0 for current detection could be adjusted without feedback resistance.

  A low current detection resistance value R0 has a small error on the high current side. This is because the amount of heat generated is small even with the same current because the resistance value is small.

  As described above in detail, according to the present embodiment, the current detection resistor module 100 determines the low resistance substrate 120 of the current detection resistor R0 having a load resistance value of 10 mΩ or less and the amplification factor of the non-inverting amplifier. A feedback resistor block 150 including feedback resistors R1 and R2 and an operational amplifier 160 having a non-inverting amplifier that amplifies a voltage generated by a current flowing through the current detection resistor R0. The feedback resistance ratio of the feedback resistors R1 and R2 is adjusted so as to eliminate the error of the current detection resistor. Adjustment of the feedback resistance ratio trims the feedback resistance R1 or R2. That is, the current detection resistor having a low resistance value trims the feedback constant of the amplifier circuit, thereby adjusting the amplification factor of the non-inverting amplifier in accordance with the error of the resistance value to achieve high accuracy. This enables highly accurate current detection using a low resistance value with little energy loss.

  For example, in the current detection resistor module 100 of FIG. 8, when the flowing current is constant, the relationship between the error of the current detection resistor and the output voltage error is proportional. When the error of the current detection resistor is + 1%, the output voltage error is also + 1%. Further, when the current detection resistance is constant, the relationship between the feedback resistance ratio error and the output error is also proportional, and when the feedback resistance ratio error is + 1%, the output voltage error is also + 1%. From these relationships, it can be seen that the accuracy of the output voltage is determined by the error of the current detection resistor and the error of the feedback resistor, and the two errors affect each other. By utilizing this, the error of the current detection resistor can be absorbed by adjusting the feedback resistance ratio, and the accuracy of the detection circuit can be improved.

  As described in the prior art, in the resistance method, it is necessary to set the current detection resistor to be small in order to avoid the effects of energy loss and heat generation due to the power consumption of the current detection resistor. If it is set to a small value such as the following, the accuracy of the current detection resistor cannot be obtained. There are also many problems such as high measurement difficulty and inability to correctly evaluate accuracy problems. On the other hand, in this embodiment, the current detection resistor and the feedback resistors R1 and R2 of the non-inverting amplifier are matched to improve the output accuracy. As a result, high accuracy can be ensured even if the current detection resistance is reduced. The adjustment of the feedback resistance ratio is an adjustment of the normal resistance value range, and there is no problem that the extremely small conductor resistance or the like affects the accuracy, and there is no problem of measurement.

  Further, when the noise generated in the current circuit or the value of the current detection resistor becomes small, an error due to the influence of the inductance occurs. In the present embodiment, the current detection resistor module 100 integrates the current detection resistor and the feedback resistors R1 and R2, and the current detection resistor input line is fixed, and the distance to the amplifier is fixed. Is also shortened. For this reason, it is possible to efficiently dispose a filter that removes noise and reduces the influence of inductance at the input unit, and more accurate current detection is possible.

  In the present embodiment, the feedback resistor R2 of the feedback resistors R1 and R2 is trimmed, but the feedback resistor R1 may be trimmed.

  It is also possible to trim the current detection resistor with high accuracy by making the feedback resistance ratio constant, and the same effect can be obtained with either the feedback resistor or the current detection resistor as the trimming target.

(Embodiment 2)
The second embodiment is an example in which the present invention is applied to a current detection resistor module having an external operational amplifier.

  13 to 15 are diagrams showing the configuration of the current detection resistor module according to Embodiment 2 of the present invention. FIG. 13 is a perspective view of the current detection resistor module, and FIG. 14 is an exploded perspective view of the current detection resistor module. 15A is a front view of the current detection resistor module, FIG. 15B is a back view of the current detection resistor module, FIG. 15C is a top view of the current detection resistor module, and FIG. 15D. These are side views of a current detection resistance module.

  In the description of the present embodiment, the same components as those in FIGS. 5 to 7 are denoted by the same reference numerals, and description of overlapping portions is omitted.

  As shown in FIGS. 13 to 15, the current detection resistor module 300 includes a glass epoxy substrate 110 and a low resistance substrate 120 disposed on one surface 110 a of the glass epoxy substrate 110.

  The current detection resistor module 300 is formed on the other surface 110b of the glass epoxy substrate 110 so as to cover the wiring 330 formed of photoresist or the like, the wiring 330 other than the terminals, and the surface 110b of the glass epoxy substrate 110. And a solder resist 340. A hole 340 a for allowing a current to flow through the current terminals 121 and 122 of the low resistance substrate 120 is formed in a corresponding portion of the solder resist 340.

  The current detection resistor module 300 includes a feedback resistor block 150 containing a feedback resistor.

  The current detection resistor module 300 does not have an operational amplifier on the module. In the current detection resistor module 300, an external operational amplifier 400 (see FIG. 16) can be externally attached to the wiring 330 terminal.

  The current detection resistor module 300 has a structure in which the operational amplifier 160 is removed from the current detection resistor module 100 of FIGS. Accordingly, a part of the wiring 330 connected to the operational amplifier 160 is omitted. Further, the solder resist 340 is omitted from the opening portion of the portion connected to the operational amplifier 160.

  FIG. 16 is a circuit diagram illustrating trimming of the current detection resistor module 300. The same components as those in FIG. 8 are denoted by the same reference numerals, and description of overlapping portions is omitted.

  As shown in FIG. 16, the current detection resistor module manufacturing system includes a current detection resistor module 300, an external operational amplifier 400, a constant current power source 200, a trimming control signal generation device 210, and a trimming control device 220. .

  The current detection resistor module 300 is a non-inverting amplifier circuit including a current detection resistor R0 of the low resistance substrate 120 and feedback resistors R1 and R2 of the external operational amplifier 400.

  When the external operational amplifier 400 is attached to the current detection resistor module 300, the positive input terminal is connected to the current terminal (input terminal) 121 side of the current detection resistor module 300, and the negative input terminal is connected to the resistor R1 and the resistor. The detection voltage Vout of the current detection resistor module 300 is output from the output terminal 133 by being connected to the connection point of R2.

  As in the current detection resistor module 100 of FIGS. 5 to 7, the current detection resistor module 300 has the current detection accuracy of the current detection resistor that provides the current detection resistor R 0 and the feedback resistor R 1 of the operational amplifier 160. , R2 ratio accuracy.

  The constant current power source 200 is connected to the current terminals 121 and 122 of the low resistance substrate 120 of the current detection resistor module 300. The constant current power source 200 causes a constant current to flow through the current terminals 121 and 122 of the low resistance substrate 120 of the current detection resistor module 300. As a result, the current Iin flows through the current detection resistor R0, and the voltage V0 is generated at both ends.

  The output terminal 133 of the current detection resistor module 300 is connected to the input terminal of the trimming control signal generator 210.

  Hereinafter, trimming of the current detection resistor module 300 configured as described above will be described. The basic operation is the same as the trimming operation of the current detection resistor module 100 of FIGS.

  In the present embodiment, the current detection resistor module 300 does not have an operational amplifier. For this reason, the current detection resistor module 300 is equipped with the external operational amplifier 400 and operates the external operational amplifier 400 during trimming to perform trimming.

  Thus, since the current detection resistor module 300 uses the non-inverting amplifier 400 that amplifies the voltage generated by the current flowing through the current detection resistor as the external operational amplifier 400, a desired operational amplifier can be used. The application range can be expanded.

(Embodiment 3)
Embodiment 3 is a prototype of a current detection resistor module.

  FIG. 17 is a circuit diagram illustrating a configuration example of a current detection resistor module using a non-inverting amplifier circuit. The same components as those in FIG. 8 are denoted by the same reference numerals.

  As shown in FIG. 17, the current detection resistor module 500 is a current detection circuit including a current detection resistor R0, operational amplifiers 511 to 513, and feedback resistors R1 to R7. The amplifier circuit is an instrumentation amplifier using three operational amplifiers 511 to 513. The operational amplifiers 511 to 513 constitute an operational amplifier block 510, and the feedback resistors R 1 to R 7 constitute a feedback resistor block 520.

  The current detection resistor module 500 has a module structure similar to that of the current detection resistor module 100 of FIGS. 5 to 7 or the current detection resistor module 300 of FIGS. 13 to 15. For example, when the current detection resistor module 500 is applied to the current detection resistor module 100 of FIGS. 5 to 7, a feedback resistor block 520 is attached in place of the feedback resistor block 150 of FIGS. 5 to 7, and FIGS. A feedback resistor block 520 is attached instead of the operational amplifier 160 of FIG.

  In FIG. 17, when the current Iin flows, a voltage is generated between the terminals T1 and T2 of the current detection resistor R0. The current detection resistor module 500 that amplifies this voltage with the three operational amplifiers 511 to 513 and the seven-element feedback resistor block 520 outputs a voltage proportional to the current Iin between the ground and the OUT terminal.

  The constants of the current detection resistor module 500 are designed as follows.

Current detection resistor R0 = 500μΩ (0.5mΩ)
Feedback resistor R1 = 2kΩ (trimming target resistor)
R2 = R3 = 19kΩ
R4 = R5 = 2kΩ
R6 = R7 = 20kΩ
The feedback resistor R1 is trimmed so as to obtain a constant output while monitoring the output voltage in order to absorb variations in the current detection resistor R0. The trimming method is the same as in the above embodiments.

  The amplification factor of the design value can be obtained by the following calculation formula.

Amplification factor = (1 + 2 × R2 / R1) × (R6 / R4)
= (1 + 2 × 19kΩ / 2kΩ) × (20kΩ / 2kΩ)
= 200 times The voltage generated between T1 and T2 when 10 A flows in the current Iin is 10 A × 0.5 mΩ = 5 mV. The voltage output to OUT is 5 mV × 200 times = 1000 mV (1 V). Therefore, the current detection resistor module 500 is designed to obtain an output of 1V per 10A.

  Each resistance value of the prototype example showed the following value.

R0 = 0.58mΩ (+ 16% against the design value of 0.5mΩ)
R1 = 1.625 kΩ (−18.75% with respect to the design value of 2 kΩ)
R2 = 19.051kΩ
R3 = 19.012kΩ
R4 = 2.0011kΩ
R5 = 2.0032kΩ
R6 = 20.028kΩ
R7 = 20.018kΩ
When 10 A is passed through the current Iin in this state, the output voltage from OUT is 1.417 V, which is 1.417 V / 10 A with respect to the specification of 1 V / 10 A.

  When trimming in the direction of increasing the resistance value of R1 while observing the output voltage from OUT, the output voltage gradually decreases. This is because the amplification factor of the amplifier circuit is adjusted in a decreasing direction. Gradually decreases and stops when the voltage reaches 1V. At this time, the resistance value of R1 had increased to about 2.35 kΩ. By this adjustment, the current detection resistor module 500 can obtain an output of 1 V per 10 A. For confirmation, a graph in which the output is confirmed by changing the current value is shown in FIG.

  FIG. 18 is a diagram illustrating a current detection error of the current detection resistor module 500.

  As shown in FIG. 18, an output of approximately 1 V / 10 A is obtained although the influence of temperature characteristics is slightly observed on the high current side.

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this. The current detection resistor module of each of the above embodiments can be applied to various electric devices and electronic devices.

  For example, in each of the above embodiments, a non-inverting amplifier circuit that outputs an output voltage in phase with the input voltage is used as an amplifier that amplifies the voltage generated by the current flowing through the low-resistance substrate 120 disposed on the glass epoxy substrate 110. Although described as an example, it may be configured by an inverting amplifier circuit that outputs an output voltage having a phase opposite to that of the input voltage or a differential amplifier circuit. However, the knowledge that the current detection accuracy is determined by the error of the current detection resistor and the ratio of the feedback resistor has been proved in the current detection resistor module using the non-inverting amplifier circuit.

  In each of the above embodiments, the name “current detection resistor module” is used. However, this is for convenience of explanation, and may be a current detection resistor, a current detection circuit, a current detection device, or the like.

  Furthermore, for example, the type of substrate, the type and number of resistors, the integration method, and the like constituting the current detection resistor module are not limited to the above-described embodiments.

  The current detection resistor module according to the present invention is a small electric device using a portable rechargeable battery, current detection of various and wide-ranging electric devices and electronic devices such as automobiles and various inverter circuits that require large current control from electronic devices. Useful for. In addition, since it has the effect of ensuring current detection accuracy while suppressing the generation of energy loss and heat generation due to power consumption, it should be used for the current detection part of inverter circuits used in many electrical devices to reduce power consumption. Therefore, there are many effective usage forms such as further reduction in power consumption.

100, 300, 500 Current detection resistor module 110 Glass epoxy substrate 120 Low resistance substrate 121, 122 Current terminal 130, 330 Wiring 133 Output terminal 140, 340 Solder resist 150, 520 Feedback resistor block 160 Operational amplifier 200 Constant current power supply 210 Trimming control Signal generation device 211 Feedback resistance ratio adjustment amount storage unit 212 Voltage detection unit 213 Trimming control signal generation unit 220 Trimming control device 400 External operational amplifier 510 Operational amplifier blocks 511 to 513 Operational amplifier

Claims (6)

A substrate,
A current detection resistor disposed on the substrate for detecting a current having a load resistance value of 10 mΩ or less;
A mounting portion disposed on the substrate, electrically connected to the current detection resistor, and capable of mounting an amplifier for amplifying a voltage generated by a current flowing through the current detection resistor;
The amplifier is disposed on the substrate and is electrically connected to the mounting portion, and the output voltage of the amplifier is divided by a first resistor and a second resistor, and a connection point between the first resistor and the second resistor is the amplifier. A feedback resistor consisting of the first and second resistors for determining the amplification factor of the amplifier.
The feedback resistor is a current detection resistor module in which a feedback resistance ratio between the first resistor and the second resistor is adjusted so as to eliminate an error of the current detection resistor. A substrate,
A current detection resistor disposed on the substrate for detecting a current having a load resistance value of 10 mΩ or less;
An amplifier that is disposed on the substrate and amplifies a voltage generated by a current flowing through the current detection resistor;
The amplifier is disposed on the substrate, and the output voltage of the amplifier is divided by a first resistor and a second resistor, and a connection point between the first resistor and the second resistor is fed back to an input terminal of the amplifier, A feedback resistor comprising the first and second resistors for determining an amplification factor,
The feedback resistor is a current detection resistor module in which a feedback resistance ratio between the first resistor and the second resistor is adjusted so as to eliminate an error of the current detection resistor.   The current detection resistor module according to claim 1, wherein the adjustment of the feedback resistance ratio is trimming of the first resistor or the second resistor. A feedback resistor composed of the first and second resistors is connected between the output terminal of the amplifier and the ground,
The amplifier has a non-inverting amplifier for connecting the current detection resistor to a positive input terminal, connecting a connection point of the first resistor and the second resistor to a negative input terminal, and outputting a detection voltage from an output terminal. The current detection resistor module according to claim 1 or 2. A feedback resistor composed of the first and second resistors is connected between the output terminal of the amplifier and the current detection resistor,
The amplifier is an inverting amplifier in which a positive input terminal is connected to a ground, a connection point of the first resistor and the second resistor is connected to a negative input terminal, and a detection voltage is output from an output terminal. Or the current detection resistance module of Claim 2. The amplifier has a positive input terminal connected to one end of the current detection resistor, a negative input terminal connected to the connection point of the first resistor and the second resistor, and a first detection voltage output from the output terminal. A first non-inverting amplifier that
A second input terminal for connecting the other end of the current detection resistor to the positive input terminal, connecting a connection point between the third resistor and the first resistor to the negative input terminal, and outputting a second detection voltage from the output terminal. An inverting amplifier;
A differential amplifier that connects the first detection voltage to a negative input terminal, connects the second detection voltage to a positive input terminal, and outputs the detection voltage from an output terminal. The current detection resistor module described in 1.

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