Current sensor and motor drive device

Abstract

A signal processing unit provided in this current sensor may include: a storage unit that stores a plurality of current sensitivity parameters corresponding to a plurality of current sensitivities that can be set for the current sensor; and a sensitivity setting unit that sets the current sensitivity of the current sensor on the basis of one type of current sensitivity parameter among the plurality of current sensitivity parameters stored in the storage unit. The sensitivity setting unit may: further include a reception unit that receives a selection signal indicating information for identifying said one type of current sensitivity parameter selected from the plurality of current sensitivity parameters; receive the selection signal from the outside of the current sensor via the reception unit; select said one type of current sensitivity parameter from the plurality of current sensitivity parameters; and set the current sensitivity of the current sensor.

Description

Current Sensor and Motor Drive Device

[0001] The present invention relates to a current sensor and a motor drive device.

[0002] Patent Document 1 describes that the current measurement range is expanded by using two current sensors with different magnetic sensitivities. Patent Document 2 describes that the current level of a current signal output from a Hall element is adjusted by an amplifier. Patent Document 3 describes a sensitivity switching type sensor circuit capable of significantly reducing a sudden change in a signal during amplification factor switching performed according to the magnitude of an input signal. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent No. 6190537 [Patent Document 2] U.S. Patent Application Publication No. 2016 / 0313407 [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2006-266738 General Disclosure

[0003] (Problems to be Solved by the Invention) A current sensor capable of switching the current measurement range over a wide range is desired. (Means for Solving the Problems)

[0004] A current sensor according to one aspect of the present invention may include a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows, and a signal processing unit that outputs an output signal by processing the detection signal. The signal processing unit may have a storage unit that stores a plurality of current sensitivity parameters corresponding to each of a plurality of current sensitivities that can be set for the current sensor. The signal processing unit may have a sensitivity setting unit that sets the current sensitivity of the current sensor based on one type of current sensitivity parameter stored in the storage unit. The sensitivity setting unit may have a reception unit that receives a selection signal indicating information specifying the one type of current sensitivity parameter selected from the plurality of current sensitivity parameters. The selection signal may be received from the outside of the current sensor via the reception unit, the one type of current sensitivity parameter may be selected from the plurality of current sensitivity parameters, and the current sensitivity of the current sensor may be set.

[0005] In the current sensor, the selection signal may be included in a setting command signal output during initial setup processing or setting update processing of a system equipped with the current sensor, or in a measurement command signal output when the system instructs the current sensor to measure current.

[0006] In any of the current sensors, the selection signal may be output in synchronization with a signal that instructs a change in load or operation.

[0007] In any of the current sensors, each of the multiple current measurement ranges may be determined based on each of the multiple current sensitivities.

[0008] In any of the current sensors, each of the plurality of current measurement ranges may be determined based on an upper limit and a lower limit at which the detection signal saturates, according to a plurality of current sensitivities.

[0009] Any of the current sensors may further include a VDD terminal and a VSS terminal connected to a drive power supply, an OUT terminal for outputting the output signal, and a selection signal input terminal for receiving the selection signal from an external source.

[0010] Any of the current sensors may further include an input / output terminal that outputs the output signal when set to normal mode and receives the selection signal when set to communication mode.

[0011] In any of the current sensors, there is at least one selection signal input terminal that receives the selection signal, and the current sensitivity may be determined by a fixed voltage level or a combination thereof to the at least one selection signal input terminal.

[0012] In any of the current sensors, the plurality of current measurement ranges include a first current measurement range that defines the minimum range of current values ​​and a second current measurement range that defines the maximum range of current values, wherein the maximum range may be three times or more the minimum range.

[0013] In any of the current sensors, the plurality of current measurement ranges may consist of five or more different current measurement ranges.

[0014] In any of the current sensors, the current detection unit may include at least one magnetoelectric conversion element.

[0015] In any of the current sensors, the at least one magnetoelectric conversion element may be a Hall element, a magnetoresistive element, or a coil.

[0016] In any of the current sensors, the current detection unit may include a plurality of magnetoelectric conversion elements. The plurality of current sensitivity parameters may include different drive current values ​​set for each of the plurality of magnetoelectric conversion elements, drive voltage values, or amplification factors of an amplifier that amplifies the output of each of the plurality of magnetoelectric conversion elements.

[0017] In any of the current sensors, the receiving unit may receive the selection signal with a clock signal that is synchronized with, or multiplied or divided by, the frequency of the amplification unit that amplifies the output of the current detection unit, or the frequency of the drive control unit that controls the driving of the current detection unit.

[0018] In any of the current sensors, the current sensor has an overcurrent detection function, and by sharing a processing unit for overcurrent detection with a part of the processing unit for normal current detection, the current sensitivity for overcurrent detection may be changed in conjunction with the plurality of current sensitivity parameters stored in the storage unit.

[0019] In any of the current sensors, the sensitivity setting unit may have an amplification unit that amplifies the detection signal output from the current detection unit.

[0020] In any of the current sensors, the plurality of current sensitivity parameters may include at least the amplification factor of the detection signal in the amplification unit.

[0021] In any of the current sensors, the sensitivity setting unit may have a drive control unit that outputs a drive current or drive voltage to the current detection unit. The plurality of current sensitivity parameters may include at least the current value of the drive current or the voltage value of the drive voltage output from the drive control unit.

[0022] In any of the current sensors, the at least one magnetoelectric conversion element may be a Hall element. The Hall element may include a semiconductor composed of group IV atoms, or a compound semiconductor composed of at least two combinations of group II, group III, group IV, group V, and group VI atoms.

[0023] In any of the current sensors, the at least one magnetoelectric conversion element may be a magnetoresistive element. The magnetoresistive element may be a TMR having Co, Fe, and Ni as the first component, Mg and O as the second component, and Mn as the third component, and containing at least one atom from the first component, at least one atom from the second component, and at least one atom from the third component.

[0024] In any of the current sensors, the sensitivity setting unit may have an amplification unit that amplifies the detection signal output from the current detection unit. The sensitivity setting unit may have a drive control unit that outputs a drive current to the current detection unit. The plurality of current sensitivity parameters may include the amplification factor of the detection signal in the amplification unit, and one of either the current value of the drive current output from the drive control unit or the voltage value of the drive voltage.

[0025] In any of the current sensors, each of the multiple current measurement ranges may be determined based on each of the multiple current sensitivities. The multiple current measurement ranges may include a first group of current measurement ranges and a second group of current measurement ranges. The amplification ratios of each of the detection signals associated with the first group of current measurement ranges may be different. The current values ​​of the drive currents or the voltage values ​​of the drive voltages associated with each of the second group of current measurement ranges may be different.

[0026] A current sensor according to one aspect of the present invention may include a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows, and a signal processing unit that outputs an output signal by processing the detection signal. The signal processing unit may have a storage unit that stores a plurality of current sensitivity parameters corresponding to each of a plurality of current sensitivities that can be set for the current sensor. The signal processing unit may have a sensitivity setting unit that sets the current sensitivity of the current sensor based on one of the plurality of current sensitivity parameters stored in the storage unit. The sensitivity setting unit may have an amplification unit that amplifies the detection signal output from the current detection unit. The sensitivity setting unit may have a drive control unit that outputs a drive current to the current detection unit. The sensitivity setting unit may have a reception unit that receives a selection signal indicating information that identifies the one current sensitivity parameter selected from the plurality of current sensitivity parameters.

[0027] In the current sensor, the plurality of current sensitivity parameters may include the amplification factor of the detection signal in the amplification unit, and one of the current value of the drive current or the voltage value of the drive voltage output from the drive control unit. Each of the plurality of current sensitivity parameters may be used to define each of the plurality of current measurement ranges. The plurality of current measurement ranges may include a first current measurement range group and a second current measurement range group that defines a range of current values ​​greater than the first current measurement range group. The amplification factors of each detection signal associated with the first current measurement range group may be different. The current value of each drive current or the voltage value of the drive voltage associated with the second current measurement range group may be different. The sensitivity setting unit may receive the selection signal from outside the current sensor via the receiving unit, select one type of current sensitivity parameter from the plurality of current sensitivity parameters, and set the current sensitivity of the current sensor.

[0028] In any of the current sensors, the current value of the drive current or the voltage value of the drive voltage associated with the first current measurement range group may be the same.

[0029] In any of the current sensors, the amplification factor of each of the detection signals associated with the second current measurement range group may be the same.

[0030] In any of the current sensors, an ADC may be built into the signal processing unit, and the current sensor may be capable of digital output.

[0031] A motor drive device according to one aspect of the present invention may be equipped with any of the current sensors, and the current sensitivity of the current sensor may be selected according to the capacity of the motor to be operated.

[0032] It should be noted that the above summary of the invention does not enumerate all of its features. Furthermore, subcombinations of these features may also constitute an invention.

[0033] This figure shows an example of the functional block of the current sensor according to this embodiment. This figure shows an example of the functional block of the current sensor 10 according to a modified example of this embodiment. This figure shows an example of the current measurement range and the overcurrent measurement range. This figure shows an example of a table in which the current value of the drive current and the amplification ratio of the amplification unit are registered as current sensitivity parameters in relation to each of the multiple current measurement ranges. This figure shows an example of the terminal function of the current sensor in normal mode. This figure shows an example of the terminal function of the current sensor in communication mode. This flowchart shows an example of the procedure for setting the current measurement range of the current sensor. This flowchart shows an example of the procedure for setting the current sensitivity when applied to a motor.

[0034] The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0035] Figure 1 shows an example of the functional block of the current sensor 10 according to this embodiment. Figure 2 shows an example of the functional block of the current sensor 10 according to a modified example of this embodiment. The current sensor 10 shown in Figure 2 differs from the current sensor 10 shown in Figure 1 in that it can perform overcurrent detection in addition to normal current detection.

[0036] The current sensor 10 shown in Figures 1 and 2 measures the measurement current flowing through a conductor 20 positioned adjacent to the current sensor 10. The conductor 20 may be built into the current sensor 10 and draw in the current. Alternatively, the conductor 20 may not be built into the current sensor 10, and the current sensor 10 may be positioned near or on the conductor 20. The current sensor 10 comprises a current detection unit 30 and a signal processing unit 100. The current detection unit 30 outputs a detection signal corresponding to the magnetic field generated in the conductor 20 when the measurement current flows. The current detection unit 30 includes at least one magnetoelectric conversion element. The at least one magnetoelectric conversion element may be a Hall element, a magnetoresistive element, or a coil. The Hall element may be, for example, a compound semiconductor composed of at least two types of group II, III, IV, V, and VI atoms such as InAs, GaAs, SiC, and ZnO, or a Hall element composed of silicon (Si). The magnetoresistive element may be a giant magnetoresistance (GMR) element, a semiconductor magnetoresistance (SMR) element, an anisotropic magnetoresistance (AMR) element, or a tunnel magnetoresistance (TMR) element. The tunnel magnetoresistance (TMR) element may be, for example, a TMR in which Co, Fe, and Ni are the first components, Mg and O are the second components, and Mn is the third component, and which contains at least one of the atoms included in the first component, at least one of the atoms included in the second component, and all of the atoms included in the third component.

[0037] The signal processing unit 100 outputs an output signal by processing the detection signal output from the current detection unit 30. The signal processing unit 100 may be a signal processing IC composed of a large-scale integrated circuit (LSI). The signal processing IC is a signal processing circuit made of a Si monolithic semiconductor formed on a Si substrate. The signal processing circuit processes the detection signal corresponding to the magnitude of the magnetic field output from the current detection unit 30.

[0038] The signal processing unit 100 includes a sensitivity setting unit 110 and a storage unit 120. The storage unit 120 stores a plurality of current sensitivity parameters corresponding to each of a plurality of current sensitivities that can be set for the current sensor 10. The sensitivity setting unit 110 sets the current sensitivity of the current sensor 10 based on one of the plurality of current sensitivity parameters stored in the storage unit 120. The signal processing unit 100 may receive a selection signal from outside the current sensor 10, select one of the plurality of current sensitivity parameters, and set the current sensitivity of the current sensor 10.

[0039] The sensitivity setting unit 110 includes a drive control unit 102, an amplification unit 104, and a reception unit 106. The drive control unit 102, the amplification unit 104, and the reception unit 106 are an example of a sensitivity setting unit that sets the current sensitivity of the current sensor 10.

[0040] The drive control unit 102 supplies a drive current or drive voltage to the current detection unit 30 to drive the current detection unit 30. The drive control unit 102 has a constant current source or a constant voltage source and supplies a drive current or drive voltage of a constant magnitude to the current detection unit 30. The drive control unit 102 refers to the memory unit 120 to identify the current value of the drive current or the voltage value of the drive voltage stored in the memory unit 120 as one of the current sensitivity parameters to be set, and supplies a drive current or drive voltage to the current detection unit 30 according to the identified current value. The drive control unit 102 may have a spinning current unit that switches the drive terminal and the signal detection terminal of the magnetoelectric conversion element according to a specific frequency.

[0041] The amplification unit 104 amplifies the detection signal output from the current detection unit 30 at a set amplification factor. The amplification unit 104 is an example of an amplification unit. The amplification unit 104 may include multiple amplification units. As shown in the modified example in Figure 2, the sensitivity setting unit 110 may include a first amplification unit 104a and a second amplification unit 104b as the amplification unit 104. For example, if the amplification unit 104 consists of a first amplification unit 104a and a second amplification unit 104b, the amplification factor range that can be set in the first amplification unit 104a and the amplification factor range that can be set in the second amplification unit 104b may be different. The amplification factor range that can be set in the first amplification unit 104a may be wider than the amplification factor range that can be set in the second amplification unit 104b. The setting interval for the amplification factor that can be set in the first amplification unit 104a may be wider than the setting interval for the amplification factor that can be set in the second amplification unit 104b. As a result, a rough adjustment of the amplification ratio is performed by adjusting the amplification ratio of the first amplification section 104a, and a fine adjustment of the amplification ratio is performed by adjusting the amplification ratio of the second amplification section 104b. The amplification section 104, the first amplification section 104a, and the second amplification section 104b may be operational amplifiers, or they may be composed of chopper amplifiers that are driven at a specific frequency and reduce signal offset. Furthermore, this specific frequency may be synchronized with the frequency that drives the spinning current section, or it may be a clock signal that is a multiple or divided version of that frequency.

[0042] The sensitivity setting unit 110 sets the amplification factor set in the amplification unit 104. The sensitivity setting unit 110 refers to the memory unit 120 to identify the amplification factor of the amplification unit 104 stored in the memory unit 120 as one of the current sensitivity parameters to be set, and sets the identified amplification factor in the amplification unit 104. The sensitivity setting unit 110 also sets the current value of the drive current set in the drive control unit 102. The sensitivity setting unit 110 refers to the memory unit 120 to identify the current value of the drive current of the drive control unit 102 stored in the memory unit 120 as one of the current sensitivity parameters to be set, and sets the identified current value in the drive control unit 102.

[0043] The sensitivity setting unit 110 may set the amplification factor and current value as current sensitivity parameters for the amplification unit 104 and the drive control unit 102, respectively, in synchronization with a specific frequency that drives the amplification unit 104 and the drive control unit 102.

[0044] The current sensor 10 may include an output unit that performs a predetermined process on the detection signal output from the amplification unit 104 and outputs an output signal after the process. The output unit may have an AD conversion unit that converts the detection signal, which is an analog signal output from the amplification unit 104, into a digital signal. The output unit may have, as the AD conversion unit, a ΔΣ type AD converter or an integrating type AD converter. The output unit may have a filter that performs filtering on the detection signal, which is an analog signal output from the amplification unit 104. The output unit may have a low-pass filter that acts on the detection signal converted into a digital signal by the AD conversion unit so that aliasing errors do not appear.

[0045] In the current sensor 10 configured as described above, the storage unit 120 stores a plurality of current sensitivity parameters for setting the current sensitivity of the current detection unit 30. For example, as shown in FIG. 4, the storage unit 120 may store, as the current sensitivity parameters, a table in which the current value (mA) of the drive current and the amplification factor of the amplification unit 104 are registered. In addition to the current measurement range, the table may register the magnetoelectric conversion coefficient (mT / A), which is the magnetic flux density incident on the current detection unit 30 when a measurement current flows through the conductor 20, and the magnetic sensitivity (mV / mT / mA) of the current detection unit 30.

[0046] The amplification factor, the current value of the drive current, or the voltage value of the drive voltage varies with temperature, and as a result, the current sensitivity also varies. Therefore, the accuracy can be improved by determining a correction factor so that the change is minimized within the operating temperature range. This correction factor may be included in a plurality of parameters and may be determined in association with the current sensitivity selected by a selection signal from the outside. For example, correction is performed at the time of shipment of the current sensor 10 to determine an optimal correction factor, and the correction factor is stored for each set value of the current sensitivity. When the current sensitivity is set by an external signal, an optimal setting is achieved by determining the correction factor in conjunction with the set value. Also, it is not necessary to correct all the current sensitivities at the time of shipment. It is also possible to correct only the maximum current sensitivity and the minimum current sensitivity, and calculate and determine the correction factor by calculation. When registering a plurality of types of magnetoelectric conversion coefficients in the table, the current sensor 10 may have a plurality of current detection units 30 having different magnetic sensitivities at different positions from the conductor 20. The plurality of magnetoelectric conversion elements having substantially the same magnetic sensitivity is a concept including, in addition to the plurality of magnetoelectric conversion elements having exactly the same magnetic sensitivity, a plurality of magnetoelectric conversion elements having variations in magnetic sensitivity within the range of manufacturing errors.

[0047] Also, the current sensitivity parameter may have different drive current values, voltage values of the drive voltage, or amplification factors of the amplifier unit 104 for each of the plurality of magnetoelectric conversion elements. In particular, in order to correct the different effects of heat generation from the conductor on the plurality of magnetoelectric conversion elements at different positions, it may have a correction factor for the variation due to temperature.

[0048] When a plurality of types of magnetic sensitivities are registered in the table, the current sensor 10 may have a plurality of current detection units 30 having different sensitivities from each other. The current sensitivity of the current sensor 10 is determined by the product of the magnetic sensitivity, the magnetoelectric conversion coefficient, the drive current, and the amplification factor.

[0049] Each of the plurality of current measurement ranges of the current sensor 10 configured as described above is determined based on each of the plurality of current sensitivities. The plurality of current measurement ranges may be determined, for example, based on the upper limit value and the lower limit value at which the detection signal saturates according to the plurality of current sensitivities.

[0050] Multiple current measurement ranges may include a first group of current measurement ranges and a second group of current measurement ranges. The amplification factors associated with the first group of current measurement ranges may be different, and the current values ​​of the drive currents may be the same. On the other hand, the amplification factors associated with the second group of current measurement ranges may be the same, and the current values ​​of the drive currents or the voltage values ​​of the drive voltages may be different. The second group of current measurement ranges may define a range of current values ​​larger than that of the first group of current measurement ranges.

[0051] The reception unit 106 receives a selection signal indicating information that identifies the current sensitivity parameter to be set, selected from among a plurality of current sensitivity parameters. The reception unit 106 may function as an input / output interface for inputting signals such as selection signals from an external source, or outputting signals to an external source. The reception unit 106 may consist of multiple terminals. The reception unit 106 may receive a selection signal indicating information that identifies the current sensitivity parameter to be set, selected by the user from among a plurality of current sensitivity parameters. The reception unit 106 may receive a selection signal indicating information that identifies the current measurement range to be set, selected from among a plurality of current measurement ranges. The plurality of current measurement ranges may be defined by, for example, five or more types.

[0052] The current sensor 10 has a selection signal input terminal that receives a selection signal for current sensitivity. The current sensor 10 may also have a VDD terminal and a VSS terminal that are connected to the high voltage side and low voltage side of the drive power supply. The current sensor 10 may also have an OUT terminal that outputs a current measurement signal.

[0053] The current sensor 10 shown in Figure 2 has an overcurrent detection terminal (OCD terminal) whose output changes when a preset threshold is exceeded. When a certain threshold is exceeded, the logic of the output of this overcurrent detection terminal changes from High to Low or from Low to High. A system equipped with a microcontroller that detects overcurrents can perform actions such as detecting a fault based on the output of the overcurrent detection terminal and stopping the system, or detecting a change in load and changing the control method.

[0054] The memory unit 120 is composed of, for example, an EEPROM or registers and stores the current sensitivity parameters that have been saved in advance. The sensitivity setting unit 110 sets the current sensitivity by writing the selection signal received by the reception unit 106 to a specific address for setting the current sensitivity. The selection signal stored in the memory unit 120 does not volatilize even when the power is turned off, and the sensitivity setting unit 110 can respond to setting changes as needed by periodically reading the selection signal from the specific address.

[0055] When the current sensor 10 performs overcurrent detection, the current sensitivity of the current sensor 10 is lower and the measurement range is wider than when it performs normal current detection. For example, it is desirable that the current measurement range for overcurrent detection be about two to three times that of normal current detection. The measurement range for current detection and the measurement range for overcurrent detection are always proportional, and the current sensitivity for overcurrent detection may be changed simultaneously according to the current sensitivity selected by an external signal.

[0056] The current detection unit 30 outputs a detection signal corresponding to the magnetic field generated in the conductor 20 when the measured current flows. In the current sensor 10 shown in Figure 2, the signal processing unit 100 includes a first amplification unit 104a and a second amplification unit 104b as an amplification unit 104. Furthermore, the signal processing unit 100 includes a comparator 105 for detecting overcurrent. The first amplification unit 104a and the comparator 105 function as an overcurrent detection unit 107. The output voltage amplified by the first amplification unit 104a is input to the overcurrent detection comparator 105. The comparator 105 outputs the result of comparing the input output voltage with a reference voltage as an overcurrent detection output. The second amplification unit 104b further amplifies the output output from the first amplification unit 104a and outputs its output from the OUT terminal. The sensitivity setting unit 110 fixes the amplification factor of the second amplifier 104b to two or three times the amplification factor of the first amplifier 104a, and changes the amplification factor of the first amplifier 104a according to an external signal. As a result, the current sensitivity for overcurrent detection amplified by the first amplifier 104a alone and the current sensitivity for normal current detection amplified by the first amplifier 104a and the second amplifier 104b are always proportional, and the sensitivity setting unit 110 can simultaneously change the current sensitivity for current detection and the current sensitivity for overcurrent detection according to an external signal. This method allows for a compact circuit while simplifying adjustments.

[0057] Figure 3 shows an example of the current measurement range and the overcurrent measurement range. The overcurrent detection threshold can be selected within the overcurrent measurement range, and the threshold is adjusted by adjusting the reference voltage of the comparator 105. The magnitude of the reference voltage of the comparator 105 may be a magnitude corresponding to an analog voltage input to the terminal or a specific parameter uniquely identified from among multiple parameters stored in the internal storage unit 120 such as an EEPROM.

[0058] Figure 4 shows an example of a table in which the current value of the drive current and the amplification factor of the amplification unit are registered as current sensitivity parameters, associated with each of the multiple current measurement ranges. As shown in Figure 4, the multiple current measurement ranges are defined in, for example, five types (five stages), and include a first current measurement range that defines the minimum range of current values ​​and a second current measurement range that defines the maximum range of current values, with the maximum range of current values ​​being three times or more than the minimum range of current values. Thus, with the current sensor 10 according to this embodiment, the current measurement range of the current sensor 10 is not fixed before shipment, and can be set to a more appropriate current measurement range desired by the user after shipment. This reduces the management cost or risk of inventory or procurement of the current sensor 10. In addition, since it is not necessary to set the current measurement range before shipment, the design man-hours during the manufacturing stage of the current sensor 10 can be reduced.

[0059] The selection signal may be received using, for example, SPI communication or I2C communication. Furthermore, the input / output interface for the selection signal may be shared with the output terminal OUT of the current sensor 10, the CLK terminal which outputs the clock of the digital output CMOS, the terminal for the reference voltage input of the comparator 105 for overcurrent threshold adjustment, the power supply terminal VDD, etc.

[0060] Figures 5A and 5B show an example of the terminal functions of the current sensor 10. In Figure 5A, the current sensor 10 has a GND terminal, a VDD terminal, an OCD terminal, a CLK terminal, and a DOUT terminal. As shown in Figure 5A, in the normal mode for normal current detection, the current sensor 10 uses the CLK terminal and the DOUT terminal to output a current signal. In addition to the normal mode for normal current detection, the current sensor 10 also operates in a communication mode in which the receiving unit 106 receives external signals from an external device such as the MCU 200. By inputting a specific signal to a specific terminal, the sensor can switch from the normal mode to the communication mode for receiving external signals. For example, the current sensor 10 can switch to the communication mode by receiving a specific signal via the OCD terminal. When the current sensor 10 switches to the communication mode, it may switch the functions of its terminals. As shown in Figure 5B, the current sensor 10 functions as follows: the OCD terminal as the CS terminal, the CLK terminal as the SCLK terminal, and the DOUT terminal as the DIO terminal, and performs SPI communication. As a result, the receiving unit 106 has the function of processing the input selection signal and rewriting the EEPROM settings without increasing the number of ports used by the microcontroller or using an external communication module or power supply.

[0061] Furthermore, current sensitivity may be selected not only by digital communication, but also by a fixed voltage level or combination thereof applied to one or more selection signal input terminals. The signal frequency used by the reception unit 106 when receiving the selection signal may be synchronized with a specific frequency driving the amplification unit 104 and the drive control unit 102, or it may be a clock signal that has been multiplied or divided. This allows for precise control of the time at which sensitivity is changed in a system incorporating the current sensor 10. That is, at a time specified by the system, the selection signal is transmitted, and the current sensitivity parameter is changed via the reception unit 106 at a synchronized frequency and count, thus allowing for control of the change time. The time of change in the output signal of the current sensor 10 accompanying the change in current sensitivity can be controlled. In other words, the change in the output signal of the current sensor 10 accompanying the change in current sensitivity can be prevented from being measured as a change in current quantity, thus preventing errors in system control. The current sensor 10 may be equipped with a PLL (phase-locked loop) to synchronize the signal frequency of the external selection signal with a specific frequency.

[0062] Figure 6 is a flowchart showing an example of the procedure for setting the current measurement range of the current sensor 10.

[0063] The reception unit 106 receives a selection signal indicating information that identifies the current sensitivity parameter to be set, selected from among a plurality of current sensitivity parameters (S100). The selection signal may be included in the setting command signal output during the initial setup process or setting update process of the system equipped with the current sensor 10. The selection signal may be included in the measurement command output when the system equipped with the current sensor 10 instructs the current sensor 10 to measure the current.

[0064] The sensitivity setting unit 110 refers to the storage unit 120 and, based on the information that identifies the current sensitivity parameter to be set indicated by the selection signal, identifies the amplification factor of the amplification unit 104 and the current value of the drive current of the drive control unit 102, which are stored in the storage unit 120 as the current sensitivity parameter to be set (S102). The sensitivity setting unit 110 sets the identified amplification factor in the amplification unit 104 and the identified current value in the drive control unit 102 (S104).

[0065] The selection signal received in step S100 may be included in the setting command signal output during the initial setup process or setting update process of the system equipped with the current sensor 10, or in the measurement command signal output when the system instructs the current sensor 10 to measure the current. The sensitivity of the system incorporating the current sensor 10 can be set according to the load on which the system operates during shipment or initial setup. In this case, the sensitivity selection signal may be included in the initial calibration at the time of shipment or in the command during initial setup by the user. This allows the optimal current sensitivity to be set even when the load is changed, thereby improving the accuracy or efficiency of operation.

[0066] For example, if a current sensor 10 is installed in a system that includes a motor amplifier or inverter, the system can change the current sensitivity of the current sensor 10 according to the capacity of the motor that the user wants to operate with the motor amplifier. The motor amplifier may also be equipped with an automatic diagnostic function or an interface for capacity selection, and after the motor capacity is determined, the system may start operation after performing an initial setup that includes a signal to change the sensitivity of the current sensor 10 in conjunction with that capacity.

[0067] Figure 7 is a flowchart showing an example of the procedure for setting current sensitivity when applied to a motor. First, the servo motor to be operated is connected to the servo amplifier (S200). Once the servo motor is connected to the servo amplifier, the microcontroller or FPGA in the system identifies the capacity of the servo motor to which the servo amplifier is connected, either through a diagnostic function or user selection (S202). The microcontroller or FPGA then determines the current instruction value according to the capacity (S204).

[0068] The microcontroller or FPGA outputs a selection signal according to the current instruction value. The sensitivity setting unit 110 changes the current sensitivity setting of the current sensor 10 based on the input selection signal (S206). After that, the microcontroller or FPGA starts the servo motor (S208).

[0069] The microcontroller or FPGA outputs a selection signal to the current sensor 10 each time the connected servo motor is changed. The sensitivity may be changed in accordance with load fluctuations during system operation. For example, when a rotating motor stops, the system may gradually change the sensitivity in accordance with the current decay. Alternatively, the system may sense the stop from a signal from an external sensor such as an encoder and switch the current sensitivity from high current to low current. The timing of the microcontroller or FPGA outputting the selection signal may be synchronized with the switch drive signal to the inverter's gate driver. In other words, the output of the selection signal from the system or microcomputer CPU may be synchronized with, for example, a signal to turn on or off a power device that outputs a control current.

[0070] As described above, according to this embodiment, with the current sensor 10, the current measurement range of the current sensor 10 is not fixed before shipment, and can be set to a more appropriate current measurement range desired by the user after shipment. This reduces the management cost or risk of inventory or procurement of the current sensor 10. Also, since it is not necessary to set the current measurement range before shipment, the design man-hours during the manufacturing stage of the current sensor 10 can be reduced. Furthermore, when a user operates a motor that does not match the assumed capacity of the motor amplifier, the dynamic range of current detection is lost, and the accuracy deteriorates. Similarly, if the operation of a motor or the like is changed, the current of the controlled object changes, so the accuracy deteriorates. For example, a large current flows when rotating, but a very small current needs to be controlled when stopped. By installing the current sensor 10 and selecting the current sensitivity according to the motor being operated and its operation, current detection can be optimized, enabling the motor amplifier to be used more flexibly and its accuracy to be improved.

[0071] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0072] It should be noted that the execution order of operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be performed in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, this does not mean that it is mandatory to perform the operations in that order.

[0073] 10 Current sensor 20 Conductor 30 Current detection unit 100 Signal processing unit 102 Drive control unit 104 Amplifier unit 104a First amplifier unit 104b Second amplifier unit 105 Comparator 106 Receiving unit 107 Overcurrent detection unit 110 Sensitivity setting unit 120 Memory unit 200 MCU

Claims

1. A current sensor comprising: a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows; and a signal processing unit that outputs an output signal by processing the detection signal, wherein the signal processing unit has a storage unit that stores a plurality of current sensitivity parameters corresponding to each of a plurality of current sensitivities that can be set for the current sensor; and a sensitivity setting unit that sets the current sensitivity of the current sensor based on one of the plurality of current sensitivity parameters stored in the storage unit, wherein the sensitivity setting unit has a reception unit that receives a selection signal indicating information that identifies the one current sensitivity parameter selected from the plurality of current sensitivity parameters, and the current sensor receives the selection signal from outside the current sensor via the reception unit, selects the one current sensitivity parameter from the plurality of current sensitivity parameters, and sets the current sensitivity of the current sensor.

2. The current sensor according to claim 1, wherein the selection signal is included in a setting command signal output during initial setup processing or setting update processing of a system equipped with the current sensor, or in a measurement command signal output when the system instructs the current sensor to measure current.

3. The current sensor according to claim 1, wherein the selection signal is output in synchronization with a signal that instructs a change in load or operation.

4. The current sensor according to claim 1, wherein each of the multiple current measurement ranges is determined based on each of the multiple current sensitivities.

5. The current sensor according to claim 4, wherein each of the plurality of current measurement ranges is determined based on an upper limit and a lower limit at which the detection signal saturates according to a plurality of current sensitivities.

6. The current sensor according to claim 1, further comprising a VDD terminal and a VSS terminal connected to a drive power supply, an OUT terminal for outputting the output signal, and a selection signal input terminal for receiving the selection signal from an external source.

7. The current sensor according to claim 1, further comprising an input / output terminal that outputs the output signal when set to normal mode and receives the selection signal when set to communication mode.

8. The current sensor according to claim 1, having at least one selection signal input terminal that receives the selection signal, and receiving current sensitivity by a fixed voltage level or combination thereof to the at least one selection signal input terminal.

9. The current sensor according to claim 4, wherein the plurality of current measurement ranges include a first current measurement range that defines a minimum range of current values ​​and a second current measurement range that defines a maximum range of current values, and the maximum range is three times or more the minimum range.

10. The current sensor according to claim 9, wherein the plurality of current measurement ranges consist of five or more current measurement ranges.

11. The current sensor according to any one of claims 1 to 10, wherein the current detection unit includes at least one magnetoelectric conversion element.

12. The current sensor according to claim 11, wherein the at least one magnetoelectric conversion element is a Hall element, a magnetoresistive element, or a coil.

13. The current sensor according to claim 1, wherein the current detection unit includes a plurality of magnetoelectric conversion elements, and the plurality of current sensitivity parameters include different drive current values ​​set for each of the plurality of magnetoelectric conversion elements, a drive voltage value, or the amplification factor of an amplifier that amplifies the output of each of the plurality of magnetoelectric conversion elements.

14. The current sensor according to claim 1, wherein the receiving unit receives the selection signal in synchronization with a clock signal that drives an amplification unit that amplifies the output of the current detection unit, or a drive control unit that controls the driving of the current detection unit, or with a clock signal that has been multiplied or divided.

15. The current sensor according to claim 1, wherein the current sensor has an overcurrent detection function, and by sharing a processing unit for overcurrent detection with a part of the processing unit for normal current detection, the current sensitivity for overcurrent detection is changed in conjunction with the plurality of current sensitivity parameters stored in the storage unit.

16. The current sensor according to claim 1, wherein the sensitivity setting unit has an amplification unit that amplifies the detection signal output from the current detection unit, and the plurality of current sensitivity parameters include at least the amplification factor of the detection signal in the amplification unit.

17. The current sensor according to claim 1, wherein the sensitivity setting unit has a drive control unit that outputs a drive current or drive voltage to the current detection unit, and the plurality of current sensitivity parameters include at least the current value of the drive current or the voltage value of the drive voltage output from the drive control unit.

18. The current sensor according to claim 11, wherein the at least one magnetoelectric conversion element is a Hall element, and the Hall element comprises a semiconductor made of Group IV atoms, or a compound semiconductor made of at least two combinations of Group II, Group III, Group IV, Group V, and Group VI atoms.

19. The current sensor according to claim 11, wherein the at least one magnetoelectric conversion element is a magnetoresistive element, and the magnetoresistive element is a TMR having Co, Fe, and Ni as first components, Mg and O as second components, and Mn as third components, and containing at least one atom from the first component, at least one atom from the second component, and at least one atom from the third component.

20. The current sensor according to claim 1, wherein the sensitivity setting unit comprises an amplification unit that amplifies the detection signal output from the current detection unit, and a drive control unit that outputs a drive current to the current detection unit, and the plurality of current sensitivity parameters include the amplification factor of the detection signal in the amplification unit, and one of the current value of the drive current output from the drive control unit or the voltage value of the drive voltage.

21. The current sensor according to claim 20, wherein each of a plurality of current measurement ranges is determined based on each of the plurality of current sensitivities, the plurality of current measurement ranges includes a first current measurement range group and a second current measurement range group, the amplification ratio of each of the detection signals associated with the first current measurement range group is different, and the current value of each of the drive currents or the voltage value of the drive voltages associated with each of the second current measurement range groups is different.

22. A current sensor comprising: a current detection unit that outputs a detection signal corresponding to a magnetic field generated in a conductor when a measurement current flows; and a signal processing unit that outputs an output signal by processing the detection signal, wherein the signal processing unit includes: a storage unit that stores a plurality of current sensitivity parameters corresponding to each of a plurality of current sensitivities that can be set for the current sensor; and a sensitivity setting unit that sets the current sensitivity of the current sensor based on one of the plurality of current sensitivity parameters stored in the storage unit, wherein the sensitivity setting unit includes: an amplification unit that amplifies the detection signal output from the current detection unit; a drive control unit that outputs a drive current to the current detection unit; and a reception unit that receives a selection signal indicating information that identifies the one of the plurality of current sensitivity parameters selected from the plurality of current sensitivity parameters, wherein the plurality of current sensitivity parameters include the amplification factor of the detection signal in the amplification unit and one of the current value of the drive current or the voltage value of the drive voltage output from the drive control unit, and each of a plurality of current measurement ranges is determined based on each of the plurality of current sensitivities, The plurality of current measurement ranges include a first current measurement range group and a second current measurement range group that defines a range of current values ​​larger than the first current measurement range group, the amplification ratio of each of the detection signals associated with the first current measurement range group is different, and the current value of each of the drive currents or the voltage value of the drive voltage associated with each of the second current measurement range groups is different, and the sensitivity setting unit receives the selection signal from outside the current sensor via the receiving unit, selects one type of current sensitivity parameter from the plurality of current sensitivity parameters, and sets the current sensitivity of the current sensor, the current sensor.

23. The current sensor according to claim 21 or 22, wherein the current value of each of the drive currents or the voltage value of the drive voltage associated with the first current measurement range group is the same, and the amplification factor of each of the detection signals associated with the second current measurement range group is the same.

24. The current sensor according to claim 1, wherein the signal processing unit has an ADC built in, and the current sensor is capable of digital output.

25. A motor drive device equipped with a current sensor according to any one of claims 1 to 10 or any one of claims 22 to 24, and selecting the current sensitivity of the current sensor according to the capacity of the motor to be operated.

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