CN114222926A - Current detection device, motor control device, and current detection method - Google Patents

Current detection device, motor control device, and current detection method Download PDF

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Publication number
CN114222926A
CN114222926A CN202080057159.0A CN202080057159A CN114222926A CN 114222926 A CN114222926 A CN 114222926A CN 202080057159 A CN202080057159 A CN 202080057159A CN 114222926 A CN114222926 A CN 114222926A
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China
Prior art keywords
signal
current
detection
switching element
output
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CN202080057159.0A
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Chinese (zh)
Inventor
角本茂生
指田和之
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Shindengen Electric Manufacturing Co Ltd
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Shindengen Electric Manufacturing Co Ltd
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Publication of CN114222926A publication Critical patent/CN114222926A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G01R15/202—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using Hall-effect devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only

Abstract

A current detection device according to the present invention is a current detection device for detecting a current flowing through an inverter unit that has a first switching element and a second switching element connected in series and generates an ac signal, the current detection device including: a first rogowski coil for detecting a current flowing through the first switching element; a second rogowski coil for detecting a current flowing through the second switching element; and a detection processing unit that generates a synthesized signal obtained by adding a first detection signal obtained by integrating the output of the first helical coil and a second detection signal obtained by integrating the output of the second helical coil, and detects the output current of the alternating current signal based on the synthesized signal.

Description

Current detection device, motor control device, and current detection method
Technical Field
The invention relates to a current detection device, a motor control device and a current detection method.
Background
Conventionally, in driving a vehicle such as an electric vehicle, it is necessary to drive a motor to which a large current is supplied from a battery, and in driving control of the motor, precise current detection is necessary. As a conventional technique for detecting a current, a technique using a solenoid coil is known (for example, see patent document 1). In such a conventional technique, the current value is estimated from a linear approximation characteristic of the output peak of the rogowski coil.
[ Prior Art document ]
[ patent document 1 ] republishing WO2017/150726 publication
However, in the above-described conventional technique, since an error in the detected current value depends on the sampling period, it may be difficult to perform accurate current detection due to, for example, insufficient resolution of the sampling period.
The present invention has been made to solve the above-described problems, and an object thereof is to provide a current detection device, a motor control device, and a current detection method capable of reducing a detection error of a current value due to insufficient resolution of a sampling period.
Disclosure of Invention
【1】 A current detection device according to an aspect of the present invention is a current detection device for detecting a current flowing through an inverter unit that has a first switching element and a second switching element connected in series and generates an ac signal, the current detection device including: a first rogowski coil for detecting a current flowing through the first switching element; a second rogowski coil for detecting a current flowing through the second switching element; and a detection processing unit that generates a synthesized signal obtained by adding a first detection signal obtained by integrating the output of the first helical coil and a second detection signal obtained by integrating the output of the second helical coil, and detects the output current of the ac signal based on the synthesized signal.
【2】 In the current detection device according to the aspect of the present invention, the inverter unit includes a plurality of groups of the first switching elements and the second switching elements, and generates ac signals having phases different from each other corresponding to the plurality of groups of the first switching elements and the second switching elements, the current detection device includes the first and second helical coils corresponding to the plurality of groups, respectively, and the detection processing unit generates the combined signal corresponding to the plurality of groups, and detects the output current of the ac signal having each of the phases different from each other based on the combined signal.
【3】 In the current detection device according to the aspect of the present invention, the detection processing unit may detect a total value obtained by summing the first detection signals corresponding to the respective groups as the input current of the inverter unit.
【4】 In the current detection device according to the aspect of the present invention, the detection processing unit detects a negative current of the alternating current signal of one phase having a negative current cycle among the plurality of alternating current signals having mutually different phases, based on an output current of another phase other than the one phase among the plurality of alternating current signals.
【5】 A current detection device according to another aspect of the present invention is a current detection device for detecting a current flowing through an inverter unit that has a first switching element and a second switching element connected in series and generates an ac signal, the current detection device including: a first solenoid coil for detecting a current flowing through the first switching element; a second solenoid for detecting a current flowing through the second switching element; and a detection processing unit that detects an output current of the ac signal based on a detection signal having a larger duty ratio, which is obtained by integrating an output of the first rogowski coil, and a second detection signal obtained by integrating an output of the second rogowski coil, the detection signal being obtained by turning on the switching element.
【6】 In the current detection device according to the other aspect of the present invention, the detection processing unit generates a combined signal obtained by adding the first detection signal and the second detection signal, and detects the output current of the ac signal with respect to the combined signal during a period of the detection signal having the larger duty ratio of the first detection signal and the second detection signal.
【7】 In the current detection device according to the other aspect of the present invention, the detection processing unit detects the output current of the ac signal during a period of the detection signal having the larger duty ratio of the first detection signal and the second detection signal.
【8】 In the current detection device according to another aspect of the present invention, the detection processing unit includes: a first integrating circuit having a reset function for integrating an output of the first loop coil; and a second integration circuit having a reset function for integrating an output of the second loop coil.
【9】 The motor control device according to the present invention is characterized by comprising: the current detection device according to any one of the above; an inverter unit configured to supply the alternating current signal to a motor as a drive signal; and a motor control unit that controls switching of the first switching element and the second switching element based on the output current detected by the current detection device.
【10】 A current detection method according to the present invention is a current detection method for detecting a current flowing through an inverter unit having a first switching element and a second switching element connected in series and generating an ac signal, the current detection method including: a first generation step in which a detection processing unit integrates an output of a first solenoid that detects a current flowing through the first switching element, and generates a first detection signal; a second generation step in which the detection processing unit integrates an output of a second solenoid that detects a current flowing through the second switching element, and generates a second detection signal; and a detection processing step of generating a composite signal obtained by adding the first detection signal generated in the first generation step and the second detection signal generated in the second generation step, and detecting an output current of an ac signal from the composite signal.
【11】 Another current detection method according to the present invention is a current detection method for detecting a current flowing through an inverter unit that has a first switching element and a second switching element connected in series and generates an ac signal, the current detection method including: a first generation step in which a detection processing unit integrates an output of a first solenoid that detects a current flowing through the first switching element, and generates a first detection signal; a second generation step in which the detection processing unit integrates an output of a second solenoid that detects a current flowing through the second switching element, and generates a second detection signal; and a detection processing step of detecting an output current of the ac signal based on one of the first detection signal generated in the first generation step and the second detection signal generated in the second generation step, the one having a larger duty ratio for turning on the switching element.
Effects of the invention
According to the present invention, since the current detection device includes the first rogowski coil for detecting the current flowing through the first switching element and the second rogowski coil for detecting the current flowing through the second switching element, and the detection processing unit generates the synthesized signal obtained by adding the first detection signal obtained by integrating the output of the first rogowski coil and the second detection signal obtained by integrating the output of the second rogowski coil, and detects the output current of the alternating current signal based on the synthesized signal, the current detection device can generate the synthesized signal close to the actual waveform of the output current of the alternating current signal, and can reduce the detection error of the current value due to the insufficient resolution of the sampling period. Thus, the current detection device can realize precise current detection with a low-resolution and inexpensive structure of the sampling period.
Drawings
Fig. 1 is a block diagram showing an example of a motor control device according to a first embodiment.
Fig. 2 is a block diagram showing an example of the detection processing unit according to the first embodiment.
Fig. 3 is an exemplary circuit diagram showing an integration circuit according to the first embodiment.
Fig. 4 is a diagram illustrating the operation of the motor control unit according to the first embodiment.
Fig. 5 is a diagram showing an example of a current waveform of the motor drive according to the first embodiment.
Fig. 6 is a diagram illustrating a process of generating a synthesized signal according to the first embodiment.
Fig. 7 is a flowchart showing an example of the output current detection process of the current detection device according to the first embodiment.
Fig. 8 is a flowchart showing an example of an input current detection process of the current detection device according to the first embodiment.
Fig. 9 is a flowchart showing an example of a negative current detection process of the current detection device according to the first embodiment.
Fig. 10 is an exemplary diagram illustrating ringing (ringing) of a detection signal.
Fig. 11 is a block diagram showing an example of a motor control apparatus according to a second embodiment.
Fig. 12 is a flowchart showing an example of the detection process of the output current of the current detection device according to the second embodiment.
Fig. 13 is a block diagram showing an example of a motor control device and a current detection device according to a third embodiment.
Detailed Description
Hereinafter, a current detection device, a motor control device, and a current detection method according to one aspect of the present invention will be described with reference to the drawings.
[ first embodiment ] to provide a liquid crystal display device
Fig. 1 is a block diagram showing an example of a motor control device according to a first embodiment. As shown in fig. 1, the motor control device 1 includes: a dc power supply 2, a smoothing capacitor 4, a current detection device 10, an inverter unit 20, and a motor control unit 30. The motor control device 1 is connected to a motor 3.
The dc power supply 2 is, for example, a battery, and supplies dc power to the motor control device 1. The motor 3 is, for example, a sine wave-driven three-phase brushless motor, and is driven by ac signals (U-phase signal, V-phase signal, W-phase signal) output as drive signals from the inverter unit 20 of the motor control apparatus 1.
The smoothing capacitor 4 is connected between a power supply line L1 connected to the positive terminal of the dc power supply 2 and a ground line L2 connected to the negative terminal of the dc power supply 2, and smoothes the dc voltage supplied from the dc power supply 2.
The inverter unit 20 generates ac signals (U-phase signal, V-phase signal, W-phase signal) for driving the motor 3 based on the control of the motor control unit 30. The inverter unit 20 includes switching elements 21-1 to 21-3 and switching elements 22-1 to 22-3. The inverter unit 20 generates, as a drive signal, a three-phase sinusoidal current signal having a phase shifted by 120 degrees, for example, by switching the switching elements 21-1 to 21-3 and the switching elements 22-1 to 22-3.
In the present embodiment, the switching elements 21-1 to 21-3 correspond to upper arms which are upper switching elements (first switching elements), and any upper switching element included in the inverter unit 20 is described as the switching element 21 unless otherwise specified.
The switching elements 22-1 to 22-3 correspond to lower arms which are lower switching elements (second switching elements), and any lower switching element included in the inverter unit 20 will be described as the switching element 22 unless otherwise specified.
The switching elements 21 and 22 are connected in series between the power supply line L1 and the ground line L2, and form a full bridge circuit. The switching elements 21(21-1 to 21-3) and the switching elements 22(22-1 to 22-3) are N-type MOSFETs, for example.
Switching element 21-1 and switching element 22-1 are connected in series between power supply line L1 and ground line L2, and constitute a full bridge circuit for generating a U-phase signal, which is a U-phase drive signal. The switching element 21-1 and the switching element 22-1 are switched in accordance with the control signals (S1, S2) output from the motor control section 30, and a U-phase signal is output from a node N1 between the switching element 21-1 and the switching element 22-1 connected in series.
Switching element 21-2 and switching element 22-2 are connected in series between power supply line L1 and ground line L2, and constitute a full bridge circuit for generating a V-phase signal, which is a V-phase drive signal. The switching element 21-2 and the switching element 22-2 are switched in accordance with the control signals (S3, S4) output from the motor control section 30, and a V-phase signal is output from a node N2 between the switching element 21-2 and the switching element 22-2 connected in series.
The switching element 21-3 and the switching element 22-3 are connected in series between the power supply line L1 and the ground line L2, and constitute a full bridge circuit for generating a W-phase signal, which is a W-phase drive signal. The switching element 21-3 and the switching element 22-3 are switched in accordance with the control signals (S5, S6) output from the motor control section 30, and a W-phase signal is output from a node N3 between the switching element 21-3 and the switching element 22-3 connected in series.
In this manner, the inverter unit 20 includes a plurality of groups of the switching elements 21 and the switching elements 22, and generates ac signals (U-phase signal, V-phase signal, W-phase signal) having different phases corresponding to the plurality of groups of the switching elements 21 and the switching elements 22, respectively.
The current detection device 10 detects a current flowing through the inverter unit 20, specifically, for example, an output current of each phase drive signal (ac signal) generated by the inverter unit 20. The current detection device 10 detects an input current from the dc power supply 2 (an input current of the inverter unit 20).
The current detection device 10 includes: rogowski coils 11-1 to 11-3, Rogowski coils 12-1 to 12-3, and a detection processing unit 13.
In the present embodiment, the rogowski coils 11-1 to 11-3 are air-core coils for detecting a current flowing through the switching elements 21(21-1 to 21-3), and when the rogowski coil (first rogowski coil) for any of the switching elements 21 included in the current detection device 10 is not particularly described differently, the rogowski coil 11 will be described.
The rogowski coils 12-1 to 12-3 are air-core coils for detecting a current flowing through the switching element 22(22-1 to 22-3), and when the rogowski coil (second rogowski coil) for any switching element 22 included in the current detection device 10 is not described as being particularly different, the rogowski coil 12 will be described.
The solenoid coil 11 (first solenoid coil) detects a current flowing through the switching element 21. For example, the rogowski coil 11-1 is disposed in a signal line connecting the drain terminal of the switching element 21-1 and the power supply line L1, and detects a current flowing through the switching element 21-1. The rogowski coil 11-2 is arranged in a signal line connecting the drain terminal of the switching element 21-2 and the power supply line L1, and detects a current flowing through the switching element 21-2. The rogowski coil 11-3 is arranged in a signal line connecting the drain terminal of the switching element 21-3 and the power supply line L1, and detects a current flowing through the switching element 21-3.
For example, the rogowski coil 12-1 is arranged in a signal line connecting the source terminal of the switching element 22-1 and the ground line L2 to detect a current flowing through the switching element 22-1. The rogowski coil 12-2 is arranged in a signal line connecting the source terminal of the switching element 22-2 and the ground line L2 to detect a current flowing through the switching element 22-2. The rogowski coil 12-3 is arranged in a signal line connecting the source terminal of the switching element 22-3 and the ground line L2 to detect a current flowing through the switching element 22-3.
As described above, the current detection device 10 includes the solenoid coils 11 and 12 corresponding to the plurality of groups of the switching elements 21 and 22, respectively.
The detection processing unit 13 is a processing unit that performs processing to detect the current flowing through the inverter unit 20. The detection processing unit 13 generates a synthesized signal obtained by adding a first detection signal obtained by integrating the output of the rogowski coil 11 and a second detection signal obtained by integrating the output of the rogowski coil 12, for example, and detects the output current of the ac signal from the synthesized signal. The detection processing unit 13 generates a composite signal corresponding to each of the plurality of groups, and detects an output current of each of the ac signals having different phases from each other based on the composite signal. Specifically, the detection processing unit 13 outputs the generated composite signal as a current signal indicating an output current of the drive signal (U-phase signal, V-phase signal, W-phase signal) of the motor 3.
The detection processing unit 13 also detects a total value obtained by summing up the first detection signals corresponding to the plurality of groups of the switching elements 21 and 22 as the input current of the inverter unit 20. Specifically, the detection processing unit 13 outputs an input current signal indicating an input current (input current of the inverter unit 20).
The detection processing unit 13 detects a negative current of the drive signal (ac signal) of one phase in a negative current period among the plurality of drive signals (U-phase signal, V-phase signal, W-phase signal) having mutually different phases, based on the output current of the other phase than the one phase among the plurality of drive signals. The detection processing unit 13 calculates the sum of the output current of the V phase and the output current of the W phase during the period in which the negative current flows in the U phase drive signal, for example. The detection processing unit 13 outputs a negative current signal indicating a negative current of the drive signal (ac signal).
The detailed configuration of the detection processing unit 13 will be described later with reference to fig. 2.
The motor control unit 30 is a processor including a CPU (central processing unit) or the like, for example, and collectively controls the motor control device 1. The motor control unit 30 controls switching of the switching elements 21 and 22 based on the output current of the drive signal (ac signal) detected by the current detection device 10.
The motor control unit 30 includes, for example, an adc (analog to Digital converter), not shown, and converts the voltage of each current signal output from the detection processing unit 13 of the current detection device 10 into a current value and acquires the current value. The motor control unit 30 acquires, for example, a current value of the current signal output from the detection processing unit 13 via an ADC, and detects a current zero crossing point from the current value of the current signal. The motor control unit 30 controls switching of the switching elements 21 and 22 according to the detected zero-crossing point.
The motor control unit 30 acquires, for example, a current value of the input current signal output from the detection processing unit 13 via an ADC, and detects a maximum value of the current value of the input current signal. The motor control unit 30 uses the maximum value of the detected current value for overcurrent detection. That is, when the maximum value of the detected current value is equal to or greater than the predetermined threshold value, the motor control unit 30 determines that an overcurrent abnormality has occurred and executes an abnormality process such as stopping the driving of the motor 3.
The motor control unit 30 acquires, for example, a current value of the negative current signal output from the detection processing unit 13 via an ADC, and detects a maximum value of the current value of the negative current signal (negative current maximum value). The motor control unit 30 uses the detected maximum value of the negative current for overcurrent detection. That is, when the detected maximum negative current value is equal to or greater than the predetermined threshold value, the motor control unit 30 determines that an overcurrent abnormality has occurred, and executes an abnormality process such as stopping the driving of the motor 3.
Next, the configuration of the detection processing unit 13 will be described in detail with reference to fig. 2.
Fig. 2 is a block diagram showing an example of the detection processing unit 13 according to the present embodiment.
As shown in fig. 2, the detection processing unit 13 includes: integrating circuits 40-1 to 40-6, adders 50-1 to 50-6, and an adder 51.
In the present embodiment, the integration circuits 40-1 to 40-6 have the same configuration, and when any one of the integration circuits provided in the detection processing unit 13 is shown, the integration circuit 40 will be described as a whole unless otherwise specified.
The adders 50-1 to 50-6 have the same configuration, and when any of the adders included in the detection processing unit 13 is shown, the adder 50 will be described without any particular distinction.
The integrating circuit 40-1 is connected to the rogowski coil 11-1, and outputs a detection signal UH obtained by integrating the output of the rogowski coil 11-1. The integrating circuit 40-2 is connected to the solenoid 12-1, and outputs a detection signal UL obtained by integrating the output of the solenoid 12-1.
The integration circuit 40-3 is connected to the solenoid 11-2 and outputs a detection signal VH obtained by integrating the output of the solenoid 11-2. The integrating circuit 40-4 is connected to the solenoid coil 12-2, and outputs a detection signal VL obtained by integrating the output of the solenoid coil 12-2.
The integrating circuit 40-5 is connected to the rogowski coil 11-3, and outputs a detection signal WH obtained by integrating the output of the rogowski coil 11-3. The integrating circuit 40-6 is connected to the solenoid coil 12-3, and outputs a detection signal WL obtained by integrating the output of the solenoid coil 12-3.
The integrating circuits 40(40-1 to 40-6) have a reset function and integrate the outputs of the solenoid coils (11, 12). Here, a detailed structure of the integrating circuit 40 will be explained with reference to fig. 3.
Fig. 3 is a circuit diagram showing an example of the integrating circuit 40 according to the present embodiment.
As shown in fig. 3, the integrating circuit 40 includes: a resistor 41, an operational amplifier 42, a capacitor 43, and a reset switch 44.
The resistor 41 is connected between one end of the rogowski coil 11(12) and the inverting input terminal of the operational amplifier 42. The capacitor 43 is connected between the inverting input terminal (node N5) of the operational amplifier 42 and the output terminal (node N5) of the operational amplifier 42.
The operational amplifier 42 functions as an integrating circuit by connecting the resistor 41 and the capacitor 43. zai in the operational amplifier 42, one end of the Roots 11(12) is connected to the inverting input terminal via the resistor 41, and the other end of the Roots 11(12) is connected to the non-inverting input terminal. The operational amplifier 42 takes the output of the rogowski coil 11(12) as an input signal (IN), and outputs an output signal (OUT) obtained by integrating the output of the rogowski coil 11 (12).
The reset switch 44 is connected in parallel with the capacitor 43 between the inverting input terminal (node N4) of the operational amplifier 42 and the output terminal (node N5) of the operational amplifier 42. The reset switch 44 is a switch for resetting the output potential of the integrating circuit 40, and controls the on state in accordance with a pulse signal of the control signal S, for example. When the integrating circuit 40 is reset, the reset switch 44 is controlled to be in a conductive state (ON state).
When the reset switch 44 is controlled to be in a non-conductive state (OFF state) by the control signal S, the integration circuit 40 functions as an integration circuit.
The control signal S is controlled by, for example, the motor control unit 30 so as to reset the integration circuit 40 when the switching of the switching element 21 and the switching element 22 is stopped; when the switching elements 21 and 22 are switched, the integration circuit 40 operates.
Further, in fig. 2, the integrating circuit 40-1, the integrating circuit 40-3, and the integrating circuit 40-5 correspond to a first integrating circuit, and the detection signal UH, the detection signal VH, and the detection signal WH correspond to a first detection signal. The integration circuit 40-2, the integration circuit 40-4, and the integration circuit 40-6 correspond to a second integration circuit, and the detection signal UL, the detection signal VL, and the detection signal WL correspond to a second detection signal.
The adder 50 is a two-input analog adder, and is implemented by, for example, an adding circuit using an operational amplifier. The adder 50 adds the two input signals and outputs a combined signal.
For example, the detection signal UH and the detection signal UL are input to the adder 50-1 as two input signals, and the adder 50-1 outputs a resultant signal obtained by adding the detection signal UH and the detection signal UL as the U-phase current signal UC.
The detection signal VH and the detection signal VL are input to the adder 50-2 as two input signals, and the adder 50-2 outputs a resultant signal obtained by adding the detection signal VH and the detection signal VL as the V-phase current signal VC.
The detection signal WH and the detection signal WL are input to the adder 50-3 as two input signals, and the adder 50-3 outputs a resultant signal obtained by adding the detection signal WH and the detection signal WL as a W-phase current signal WC.
In this manner, the detection processing unit 13 generates combined signals (U-phase current signal UC, V-phase current signal VC, and W-phase current signal WC) corresponding to a plurality of groups of the switching elements 21 and 22, and detects output currents of drive signals (ac signals) having different phases from each other based on the combined signals. That is, the detection processing unit 13 outputs the generated composite signals (U-phase current signal UC, V-phase current signal VC, and W-phase current signal WC) as current signals indicating output currents for the respective drive signals (U-phase signal, V-phase signal, and W-phase signal).
The adder 50-4 receives the V-phase current signal VC and the W-phase current signal WC as two input signals, and the adder 50-4 outputs a resultant signal obtained by adding the V-phase current signal VC and the W-phase current signal WC as a U-phase negative current signal UMC. That is, the adder 50-4 outputs the negative current of the U-phase signal in the negative current period as the U-phase negative current signal UMC based on the output currents (the V-phase current signal VC and the W-phase current signal WC) of the phases other than the U-phase.
The adder 50-5 receives the U-phase current signal UC and the W-phase current signal WC as two input signals, and the adder 50-5 outputs a resultant signal obtained by adding the U-phase current signal UC and the W-phase current signal WC as a V-phase negative current signal VMC. That is, the adder 50-5 outputs the negative current of the V-phase signal in the negative current period as the V-phase negative current signal VMC based on the output currents (the U-phase current signal UC and the W-phase current signal WC) of the phases other than the V-phase.
The adder 50-6 receives the U-phase current signal UC and the V-phase current signal VC as two input signals, and the adder 50-6 outputs a resultant signal obtained by adding the U-phase current signal UC and the V-phase current signal VC as a W-phase negative current signal WMC. That is, the adder 50-6 outputs the negative current of the W-phase signal in the negative current period as the W-phase negative current signal WMC based on the output currents (the U-phase current signal UC and the V-phase current signal VC) of the phases other than the W-phase.
In this manner, the detection processing unit 13 detects a negative current of the drive signal of one phase in the negative current period among the three-phase drive signals (U-phase signal, V-phase signal, and W-phase signal) based on the output currents (current signals) of the phases other than the one phase among the plurality of drive signals. The detection processing unit 13 outputs the generated negative current signals (U-phase negative current signal UMC, V-phase negative current signal VMC, and W-phase negative current signal WMC) as current signals indicating a negative current for each drive signal.
The adder 51 is a three-input analog adder, and is realized by an addition circuit using an operational amplifier, for example. The adder 51 adds the three input signals and outputs a composite signal. Detection signal UH, detection signal VH, and detection signal WH are input to adder 51 as three input signals, and adder 51 outputs a resultant signal obtained by adding detection signal UH, detection signal VH, and detection signal WH as input current signal BTC.
In this manner, the detection processing unit 13 detects the total value of the three first detection signals (the detection signal UH, the detection signal VH, and the detection signal WH) as the input current of the converter unit 20. That is, the detection processing unit 13 outputs the input current signal BTC as a current signal indicating the input current.
Next, operations of the motor control device 1 and the current detection device 10 according to the present embodiment will be described with reference to the drawings.
First, the switching operation of the motor control unit 30 will be described with reference to fig. 4 and 5.
Fig. 4 is a diagram illustrating an operation of the motor control unit 30 according to the present embodiment. Fig. 5 is an exemplary diagram showing a current waveform of the motor drive in the present embodiment.
In fig. 4, "driving state" indicates a state of a driving signal when 360 degrees is set for 1 cycle, and is divided into 6 states of state ST1 to state ST 6. The motor controller 30 performs switching control shown in fig. 4, and performs 180-degree energization control.
The "U-phase upper arm" represents control of the U-phase upper switching element 21-1, and the "U-phase lower arm" represents control of the U-phase lower switching element 22-1. The "upper arm of the V phase" indicates control of the upper switching element 21-2 for the V phase, and the "lower arm of the V phase" indicates control of the lower switching element 22-2 for the V phase. The "upper arm of the W phase" indicates control of the upper switching element 21-3 for the W phase, and the "lower arm of the W phase" indicates control of the lower switching element 22-3 for the W phase.
As shown in fig. 4, the motor controller 30 switches the switching elements 21-1 and 22-1 between the state ST1 and the state ST3 by the control signal S1 and the control signal S2 as the control of the U-phase drive signal. In this case, "SW" indicates a switching operation by PWM (pulse width modulation), and "/SW" indicates inversion control of switching by "SW". In the control of the U-phase drive signal, the motor controller 30 turns off the switching element 21-1 by the control signal S1 and turns on the switching element 22-1 by the control signal S2 from the state ST4 to the state ST 6.
As control of the V-phase drive signal, the motor control section 30 performs switching of the switching element 21-2 and the switching element 22-2 by the control signal S3 and the control signal S4 during the state ST3 to the state ST 5. In the control of the V-phase drive signal, the motor control unit 30 turns off the switching element 21-2 by the control signal S3 and turns on the switching element 22-2 by the control signal S4 during the states ST6, ST1, and ST 2.
As control of the W-phase drive signal, the motor controller 30 performs switching of the switching element 21-3 and the switching element 22-3 by the control signal S5 and the control signal S6 during the state ST5, the state ST6, and the state ST 1. In the control of the W-phase drive signal, the motor controller 30 turns off the switching element 21-3 by the control signal S5 and turns on the switching element 22-3 by the control signal S6 during the period from the state ST2 to the state ST 4.
In fig. 5, a waveform W1 represents a current waveform of the U-phase, a waveform W2 represents a current waveform of the W-phase, and a waveform W3 represents a current waveform of the W-phase.
The motor controller 30 performs the switching control shown in fig. 4, and supplies the drive signal of the current waveform shown by the waveform W1 to the waveform W3 in fig. 5 to the motor 3 to drive the motor 3.
Next, the current signal generation process performed by the detection processing unit 13 of the current detection device 10 will be described with reference to fig. 6.
Fig. 6 is a diagram for explaining the process of generating a synthesized signal in the present embodiment.
In fig. 6, a waveform W4 shows a voltage waveform of the detection signal UH, a waveform W5 shows a voltage waveform of the detection signal UL, and a waveform W6 shows a voltage waveform of the U-phase current signal UC.
As shown in fig. 6, the integrating circuit 40-1 of the detection processing unit 13 integrates the output of the rogowski coil 11-1 and outputs a detection signal UH shown by a waveform W4. The integration circuit 40-2 of the detection processing unit 13 integrates the output of the rogowski coil 12-1 and outputs a detection signal UL as shown by a waveform W5.
Next, the adder 50-1 outputs a U-phase current signal UC indicated by a waveform W6 as a combined signal obtained by adding the detection signal UH indicated by the waveform W4 and the detection signal UL indicated by the waveform W5. The U-phase current signal UC is a signal obtained by converting the output current (positive current) of the U-phase drive signal into a voltage.
The detection processing unit 13 also generates and outputs a V-phase current signal VC and a W-phase current signal WC in the same manner as the U-phase current signal UC. That is, the detection processing unit 13 generates the U-phase current signal UC, the V-phase current signal VC, and the W-phase current signal WC according to the following equations (1) to (3).
Formula (1): u-phase current signal UC is equal to detection signal UH + detection signal Ul
Formula (2): v-phase current signal VC equals detection signal VH + detection signal VL
Formula (3): w phase current signal WC being detection signal WH + detection signal Wl
The motor control unit 30 acquires the U-phase current signal UC, the V-phase current signal VC, and the W-phase current signal WC generated by the detection processing unit 13 via an ADC, not shown, and detects zero-crossing points of output currents of the respective phases. The motor control unit 30 performs the switching control shown in fig. 4 described above based on the detected zero-cross point.
The detection processing unit 13 generates a U-phase negative current signal UMC, a V-phase negative current signal VMC, and a W-phase negative current signal WMC by the following equations (4) to (6).
Formula (4):
u-phase negative current signal UMC ═ V-phase current signal VC + W-phase current signal WC
Detection signal VH + detection signal VL + detection signal WH + detection signal WL
Formula (5):
v-phase negative current signal VMC ═ U-phase current signal UC + W-phase current signal WC
Detection signal UH + detection signal UL + detection signal WH + detection signal WL
Formula (6):
w-phase negative current signal WMC is equal to U-phase current signal UC + V-phase current signal VC
Detection signal UH + detection signal UL + detection signal VH + detection signal VL
For example, when the U-phase negative current signal UMC is generated, the current value of the U-phase negative current signal UMC (the current value Iu of the waveform W1 shown in fig. 5) is the sum of the current value Iv of the waveform W2 shown in fig. 5 and the current value Iw of the waveform W3. Therefore, the detection processing unit 13 generates the U-phase negative current signal UMC by the above equation (4). That is, the adder 50-4 of the detection processing unit 13 adds the V-phase current signal VC and the W-phase current signal WC to generate the U-phase negative current signal UMC.
The motor control unit 30 acquires the U-phase negative current signal UMC, the V-phase negative current signal VMC, and the W-phase negative current signal WMC generated by the detection processing unit 13 via an ADC (not shown), and uses the maximum value of the negative current signal of each phase for abnormality detection (for example, overcurrent detection) during the negative current period.
The detection processing unit 13 generates the input current signal BTC by the following formula (7). That is, the adder 51 of the detection processing unit 13 generates a total value obtained by adding the detection signal UH, the detection signal VH, and the detection signal WH as the input current signal BTC.
Formula (7):
input current signal BTC ═ detection signal UH + detection signal VH + detection signal WH
The motor control unit 30 acquires the input current signal BTC generated by the detection processing unit 13 via an ADC (not shown), and uses the maximum value of the input current signal BTC for abnormality detection (e.g., overcurrent detection).
Next, a current detection method of the current detection device 10 according to the present embodiment will be described with reference to fig. 7 to 9.
Fig. 7 is a flowchart illustrating an example of the detection process of the output current of the current detection device 10 according to the present embodiment.
As shown in fig. 7, when detecting the output current (positive current) of each phase of the inverter unit 20, the current detection device 10 first integrates the output of the upper solenoid 11 to generate a first detection signal (step S101). For example, in the detection processing unit 13 of the current detection device 10, the integration circuit 40-1 integrates the output of the solenoid 11-1 to generate the detection signal UH, the integration circuit 40-3 integrates the output of the solenoid 11-2 to generate the detection signal VH, and the integration circuit 40-5 integrates the output of the solenoid 11-3 to generate the detection signal WH.
Next, the current detection device 10 integrates the output of the lower solenoid coil 12 to generate a second detection signal (step S102). For example, in the detection processing unit 13, the integration circuit 40-2 integrates the output of the solenoid coil 12-1 to generate the detection signal UL, the integration circuit 40-4 integrates the output of the solenoid coil 12-2 to generate the detection signal VL, and the integration circuit 40-6 integrates the output of the solenoid coil 12-3 to generate the detection signal WL.
The detection processing unit 13 may execute the processing of step S101 and the processing of step S102 in reverse order, or may execute the processing in parallel using the configuration shown in fig. 2, for example.
Next, the current detection device 10 adds the first detection signal and the second detection signal to generate a composite signal (step S103). For example, in the detection processing unit 13, the adder 50-1 adds the detection signal UH and the detection signal UL to generate the U-phase current signal UC as a combined signal. The adder 50-2 adds the detection signal VH and the detection signal VL to generate a V-phase current signal VC as a combined signal. Adder 50-3 adds detection signal WH and detection signal WL to generate W-phase current signal WC as a composite signal.
Next, the current detection device 10 detects an output current from the synthesized signal (step S104). For example, the detection processing unit 13 outputs the U-phase current signal UC, the V-phase current signal VC, and the W-phase current signal WC to the motor control unit 30 as current signals indicating the output currents of the respective phases. After the process of step S104, the current detection device 10 ends the detection process of the output current.
The current detection device 10 repeatedly executes the processing of step S101 to step S103. In the above description, the detection processing unit 13 detects the output currents for the three phases in parallel, but may detect the output currents of the respective phases independently. The detection processing unit 13 may detect the output current by the above-described processing only during the period in which each phase is a positive current.
Next, a process of detecting an input current by the current detection device 10 according to the present embodiment will be described with reference to fig. 8.
Fig. 8 is a flowchart illustrating an example of the input current detection process of the current detection device 10 according to the present embodiment.
As shown in fig. 8, when the input current detection process is performed, first, the current detection device 10 integrates the output of the upper compass coil 11 of each phase to generate a first detection signal of each phase (step S201). For example, in the detection processing unit 13 of the current detection device 10, the integration circuit 40-1 integrates the output of the solenoid 11-1 to generate the detection signal UH, the integration circuit 40-3 integrates the output of the solenoid 11-2 to generate the detection signal VH, and the integration circuit 40-5 integrates the output of the solenoid 11-3 to generate the detection signal WH.
Next, the current detection device 10 adds the first detection signals of the respective phases to generate an input current signal (step S202). For example, in the detection processing unit 13, the adder 51 adds the detection signal UH, the detection signal VH, and the detection signal WH to generate the input current signal BTC.
Next, the current detection device 10 detects an input current from the input current signal (step S203). For example, the detection processing unit 13 outputs the input current signal BTC to the motor control unit 30 as a current signal indicating the input current.
Further, the current detection device 10 repeatedly executes the processing of step S201 to step S203.
Next, the process of detecting a negative current by the current detection device 10 according to the present embodiment will be described with reference to fig. 9.
Fig. 9 is a flowchart showing an example of the negative current detection process of the current detection device 10 according to the present embodiment.
As shown in fig. 9, when the detection process of the negative current is performed, first, the current detection device 10 generates a synthesized signal of each phase (step S301). The current detection device 10 generates a composite signal of each phase by the processing of step S101 to step S103 shown in fig. 7.
Next, the current detection device 10 adds the synthesized signals except for the synthesized signal of the phase in the negative current period to generate a negative current signal (step S302). The detection processing unit 13 of the current detection device 10 generates a negative current signal for each phase using the above-described equations (4) to (6). In the detection processing unit 13, for example, the adder 50-4 adds the V-phase current signal VC and the W-phase current signal WC to generate the U-phase negative current signal UMC. Adder 50-5 adds U-phase current signal UC and W-phase current signal WC to generate V-phase negative current signal VMC. Adder 50-6 adds U-phase current signal UC and V-phase current signal VC to generate W-phase negative current signal WMC.
Next, the current detection device 10 detects a negative current of the ac signal from the negative current signal (step S303). For example, the detection processing unit 13 outputs the U-phase negative current signal UMC, the V-phase negative current signal VMC, and the W-phase negative current signal WMC to the motor control unit 30 as current signals indicating the respective negative current signals. After the process of step S303, the current detection device 10 ends the detection process of the negative current.
The current detection device 10 repeatedly executes the processing of steps S301 to S303. In the above description, the detection processing unit 13 detects the load currents in parallel for the three phases, but may detect the output currents of the respective phases independently. The detection processing unit 13 may detect the load current by the above-described processing only during the period in which each phase is the load current, for example.
As described above, the current detection device 10 according to the present embodiment includes the switching element 21 (first switching element) and the switching element 22 (second switching element) connected in series, and detects a current flowing through the inverter unit 20 that generates an ac signal (drive signal), and includes: a rogowski coil 11 (first rogowski coil), a rogowski coil 12 (second rogowski coil), and a detection processing unit 13. The rogowski coil 11 detects a current flowing through the switching element 21, the rogowski coil 12 detects a current flowing through the switching element 22, the detection processing unit 13 generates a synthesized signal obtained by adding a first detection signal obtained by integrating an output of the rogowski coil 11 and a second detection signal obtained by integrating an output of the rogowski coil 12, and detects an output current of an alternating current signal (drive signal) from the synthesized signal.
Thus, the current detection device 10 according to the present embodiment can generate a synthesized signal close to the actual waveform of the output current of the ac signal (drive signal), and can reduce the detection error of the current value due to the insufficient resolution of the sampling period. Therefore, the current detection device 10 according to the present embodiment can realize accurate current detection with a low-resolution and inexpensive configuration of the sampling period.
In the present embodiment, the inverter unit 20 includes a plurality of groups of the switching elements 21 and 22, and generates ac signals (U-phase signal, V-phase signal, W-phase signal) having different phases corresponding to the plurality of groups of the switching elements 21 and 22, respectively. The current detection device 10 includes a solenoid coil 11 and a solenoid coil 12 corresponding to a plurality of groups of the switching elements 21 and 22, respectively. The detection processing unit 13 generates composite signals (a U-phase current signal UC, a V-phase current signal VC, and a W-phase current signal WC) corresponding to a plurality of groups of the switching elements 21 and 22, respectively, and detects output currents of ac signals having different phases from each other based on the composite signals.
As described above, the current detection device 10 according to the present embodiment can precisely detect the output current of each of the ac signals (drive signals) of the plurality of phases (three phases of U-phase, V-phase, and W-phase) with an inexpensive configuration having a low resolution of the sampling period.
In the present embodiment, the detection processing unit 13 detects a total value obtained by summing up the first detection signals corresponding to the plurality of groups of the switching elements 21 and 22 as the input current of the inverter unit 20.
Thus, the current detection device 10 according to the present embodiment can detect the input current of the inverter unit 20 more precisely with an inexpensive configuration. Further, the motor control device 1 according to the present embodiment can detect an abnormality due to an overcurrent with high accuracy by using the input current of the inverter unit 20 detected by the current detection device 10.
In the present embodiment, the detection processing unit 13 detects a negative current of the alternating current signal (drive signal) of one phase in a negative current period among the plurality of alternating current signals (drive signals) having mutually different phases, based on the output current of the other phase except for the one phase among the plurality of alternating current signals. The detection processing unit 13 detects, for example, the maximum value obtained by adding the added value of the output currents of the other phases as the maximum value of the negative current of the ac signal (drive signal).
Thus, the current detection device 10 according to the present embodiment can detect the current of the ac signal (drive signal) during the negative current period with an inexpensive configuration. In addition, the motor control device 1 according to the present embodiment can accurately detect an abnormality due to an overcurrent in the negative current period by using the negative current of the ac signal (drive signal) detected by the current detection device 10.
In the present embodiment, the detection processing unit 13 includes: a first integration circuit (for example, integration circuit 40-1, integration circuit 40-3, and integration circuit 40-5) for integrating the output of the solenoid coil 11 and having a reset function; and a second integration circuit (for example, integration circuit 40-2, integration circuit 40-4, and integration circuit 40-6) for integrating the output of the solenoid coil 12 and having a reset function.
In this way, since the current detection device 10 according to the present embodiment can reset the integration circuit 40 at each detection, the output of the solenoid coils 11 and 12 can be accurately integrated. The current detection device 10 according to the present embodiment includes a plurality of integrating circuits 40, and can detect an output current in real time by executing processing in parallel.
The motor control device 1 according to the present embodiment includes the current detection device 10, the inverter unit 20, and the motor control unit 30. The inverter section 20 supplies the motor 3 with an ac signal as a drive signal. The motor control unit 30 controls switching of the switching elements 21 and 22 based on the output current detected by the current detection device 10.
As described above, the motor control device 1 according to the present embodiment can provide the same effect as the current detection device 10, that is, can reduce the detection error of the current value due to the insufficient resolution of the sampling period.
The current detection method according to the present embodiment, which has the switching element 21 and the switching element 22 connected in series, generates an ac signal, and detects a current flowing to the inverter unit 20, includes: a first generation step, a second generation step, and a detection processing step. In the first generation step, the detection processing unit 13 generates a first detection signal by integrating the output of the solenoid 11 that detects the current flowing through the switching element 21. In the second generation step, the detection processing unit 13 generates a second detection signal by integrating the output of the solenoid coil 12, which detects the current flowing through the switching element 22, of the switching element 22. In the detection processing step, the detection processing unit 13 adds the first detection signal generated in the first generation step and the second detection signal generated in the first generation step to generate a composite signal, and detects the output current of the ac signal from the composite signal.
As described above, the current detection method according to the present embodiment can provide the same effects as those of the current detection device 10 and the motor control device 1 described above, and can reduce a detection error of a current value due to insufficient resolution of a sampling period.
[ second embodiment ]
In the motor control device 1 of the first embodiment, since the inverter unit 20 has an influence of parasitic capacitances and the like of the snubber circuit (not shown) and the switching elements (21, 22) and an influence of switching noise of the switching elements (21, 22), a signal ringing of a current rise may occur in the detection signal obtained by integrating the output of the rogowski coils (11, 12).
Fig. 10 is an exemplary diagram illustrating detection of signal ringing.
In fig. 10, a waveform W7 shows a voltage waveform of the detection signal LU detected by the rogowski coil 12-1. In the motor control device 1 according to the first embodiment, ringing may occur when current rises as in the period TR1 shown by the waveform W7.
Therefore, in the first embodiment described above, for example, when the duty ratio in the on state of the switching elements (21, 22) is small, since the detection period of the detection signal coincides with the ringing occurrence period (for example, the period TR1), it is difficult to perform precise current detection.
Therefore, in the present embodiment, a modified example of how to reduce the influence of the ringing and realize accurate current detection will be described.
Fig. 11 is a block diagram showing an example of the motor control device 1a according to the second embodiment.
As shown in fig. 11, the motor control device 1a includes: a dc power supply 2, a smoothing capacitor 4, a current detection device 10a, an inverter unit 20, and a motor control unit 30 a.
In fig. 11, the same components as those in fig. 1 are denoted by the same symbols, and the description thereof will be omitted.
The current detection device 10a includes Rogowski coils 11-1 to 11-3, Rogowski coils 12-1 to 12-3, and a detection processing unit 13a for detecting a current flowing through an inverter unit 20.
In the present embodiment, the detection processing unit 13a and the motor control unit 30a are different in configuration, and the configuration thereof will be described below.
The basic function of the detection processing unit 13a is the same as that of the detection processing unit 13 according to the first embodiment, but differs in that the detection processing for reducing the ringing is available. The detection processing unit 13a detects the output current of the alternating current signal from one of the first detection signal obtained by integrating the output of the solenoid coil 11 and the second detection signal obtained by integrating the output of the solenoid coil 12, which has a larger duty ratio and turns on the switching elements (21, 22).
The detection processing unit 13a generates a composite signal obtained by adding the first detection signal and the second detection signal, and detects the output current of the ac signal with respect to the composite signal during a period of the detection signal having a larger duty ratio of the first detection signal and the second detection signal.
The detection processing unit 13a includes a detection preprocessing unit 131 and a detection unit 132.
The detection preprocessing unit 131 generates a first detection signal from the output of the rogowski coil 11(11-1, 11-2, 11-3), generates a second detection signal from the output of the rogowski coil 12(12-1, 12-2, 12-3), and generates a composite signal by adding the first detection signal and the second detection signal. The detection preprocessing unit 131 is, for example, the same circuit as the detection processing unit 13 of the first embodiment shown in fig. 2.
The detection unit 132 is a part of the motor control unit 30a, and includes, for example, an ADC (analog to digital converter), not shown, and acquires a current value by the ADC. The signal for converting the current waveform into a voltage includes a U-phase current signal UC, a V-phase current signal VC, and a W-phase current signal WC, and includes an input current signal BTC, a U-phase negative current signal UMC, a V-phase negative current signal VMC, a W-phase negative current signal WMC, and the like.
For example, when the current values of the U-phase current signal UC, the V-phase current signal VC, and the W-phase current signal WC are obtained (at the time of detection), the detection unit 132 obtains, as the current value, the voltage in the period of the detection signal having a larger duty ratio for turning on the switching elements (21, 22) out of the voltage in the first detection signal period and the voltage in the second detection signal period before the generation of the combined signal. That is, the detection unit 132 compares the voltage in the first detection signal period and the voltage in the second detection signal period before the composite signal is generated via the ADC chip, and adopts the voltage value having the larger duty ratio as the current value after comparing the duty ratio in the first detection signal period and the duty ratio in the second detection signal period.
Note that, when acquiring the voltage during the first detection signal and the voltage during the second detection signal, the detection unit 132 acquires the voltage value in an intermediate period during the on state of each switching element (21, 22) to reduce the influence of ringing.
The motor control unit 30a is a processor including a CPU or the like, for example, and collectively controls the motor control device 1 a. The motor control unit 30a controls switching of the switching elements 21 and 22 based on the output current of the drive signal (ac signal) detected by the current detection device 10 a. That is, the motor control unit 30a performs the same control as the motor control unit 30 according to the first embodiment.
The motor control unit 30a includes a detection unit 132 as a part of the detection processing unit 13 a.
Next, operations of the current detection device 10a and the motor control device 1a according to the present embodiment will be described with reference to the drawings.
The basic operations of the current detection device 10a and the motor control device 1a according to the present embodiment are the same as those of the first embodiment shown in fig. 7 to 9. However, in the present embodiment, the processing of step S104 shown in fig. 7 is different, and therefore the processing will be described in detail with reference to fig. 12.
Fig. 12 is a flowchart illustrating an example of the detection process of the output current of the current detection device 10a according to the present embodiment. The processing shown in this figure corresponds to the processing of step S104 shown in fig. 7.
As shown in fig. 12, the detection processing unit 13a of the current detection device 10a first detects a detection signal of the solenoid 11 (high side) (step S401). That is, the detection unit 132 of the detection processing unit 13a acquires a voltage value at a middle portion of a period in which the combined signal is in the first detection signal by an ADC not shown.
Next, the detection processing unit 13a first detects a detection signal of the rogowski coil 12 (low side) (step S401). That is, the detection unit 132 acquires the voltage value of the middle portion of the period in which the combined signal is the second detection signal via the ADC not shown.
Next, the detection unit 132 determines whether the low-side duty ratio is larger than the high-side duty ratio (step S403). When the duty ratio of the low side (the width of the on period of the switching element 22) is larger than the duty ratio of the high side (the width of the on period of the switching element 21) (yes in step S404), the detection unit 132 proceeds to step S404. When the low-side duty ratio (the width of the on period of the switching element 22) is equal to or less than the high-side duty ratio (the width of the on period of the switching element 21) (no in step S405), the detection unit 132 proceeds to step S405.
In step S404, the detection unit 132 uses the detection signal of the rogowski coil 12 (low side) as the detection value of the output current. The detection section 132 uses, as the detection value of the output current, the voltage value of the middle portion of the period in which the combined signal is the second detection signal. After the process of step S404, the current detection device 10a ends the detection process.
In step S405, the detection unit 132 uses the detection signal of the rogowski coil 11 (high side) as the detection value of the output current. The detection section 132 uses, as the detection value of the output current, the voltage value of the middle portion of the period in which the synthesized signal is the first detection signal. After the process of step S405, the current detection device 10a ends the detection process.
Current detection device 10a performs the processing shown in fig. 12 on U-phase current signal UC, V-phase current signal VC, and W-phase current signal WC as current signals indicating the output currents of the respective phases.
As described above, the current detection device 10a according to the present embodiment includes the switching element 21 (first switching element) and the switching element 22 (second switching element) connected in series, and detects a current flowing through the inverter unit 20 by generating an ac signal, and includes: a rogowski coil 11 (first rogowski coil), a rogowski coil 12 (second rogowski coil), and a detection processing unit 13 a. The rogowski coil 11 detects a current flowing through the switching element 21. The solenoid coil 12 detects a current flowing through the switching element 22. The detection processing unit 13a detects the output current of the alternating current signal from the one of the first detection signal obtained by integrating the output of the solenoid coil 11 and the second detection signal obtained by integrating the output of the solenoid coil 12, which has a larger duty ratio and turns on the switching elements (21, 22).
As described above, the current detection device 10a according to the present embodiment detects the output current using the detection signal having the larger duty ratio (the wider detection signal) of the first detection signal and the second detection signal, and thus can detect the output current while avoiding the ringing generation period. Therefore, the current detection device 10a according to the present embodiment can reduce the influence of ringing, thereby achieving accurate current detection.
In the present embodiment, the detection processing unit 13a generates a combined signal obtained by adding the first detection signal and the second detection signal, and detects the output current of the ac signal with respect to the combined signal during a period of the detection signal having the larger duty ratio of the first detection signal and the second detection signal.
As described above, the current detection device 10a according to the present embodiment can generate a synthesized signal close to the actual waveform of the output current of the ac signal (drive signal), and thus can reduce the detection error of the current value due to the lack of resolution in the sampling period. Therefore, the current detection device 10a according to the present embodiment can realize precise current detection with an inexpensive configuration having a low resolution of the sampling period, as in the first embodiment.
The motor control device 1a according to the present embodiment includes the current detection device 10a, the inverter unit 20, and the motor control unit 30 a. The inverter section 20 supplies the motor 3 with an ac signal as a drive signal. The motor control unit 30a controls switching of the switching elements 21 and 22 according to the output current detected by the current detection device 10 a.
As described above, the motor control device 1a according to the present embodiment can achieve the same effects as the current detection device 10a described above, reduce the influence of ringing, and realize accurate current detection.
The current detection method according to the present embodiment is a method for detecting a current flowing through an inverter unit 20 that has a switching element 21 and a switching element 22 connected in series and generates an ac signal, and includes a first generation step, a second generation step, and a detection processing step. In the first generation step, the detection processing unit 13a integrates the output of the solenoid 11 that detects the current flowing through the switching element 21, and generates a first detection signal. In the second generation step, the detection processing unit 13a integrates the output of the solenoid coil 12 that detects the current flowing through the switching element 22, and generates a second detection signal. In the detection processing step, the detection processing unit 13a detects the output current of the ac signal from the one of the first detection signal generated in the first generation step and the second detection signal generated in the first generation step, which has a larger duty ratio for turning on the switching element.
As described above, the current detection method according to the present embodiment can achieve the same effects as those of the current detection device 10a and the motor control device 1a, reduce the influence of ringing, and realize accurate current detection.
[ third embodiment ]
Next, the current detection device 10b and the motor control device 1b according to the third embodiment will be described with reference to the drawings.
In the present embodiment, a modification of the current detection device 10a and the motor control device 1a according to the second embodiment will be described in detail. In the present embodiment, a modification example is provided in which the first detection signal and the second detection signal are used for detection without generating a synthesized signal.
Fig. 13 is a block diagram showing an example of the motor control device 1b and the current detection device 10b according to the third embodiment.
As shown in fig. 13, the motor control device 1b includes a current detection device 10 b. The current detection device 10b includes a detection processing unit 13 b. Although not shown in fig. 13, the motor control device 1b includes the motor control unit 30a, the dc power supply 2, the smoothing capacitor 4, and the inverter unit 20, which are similar to those of the second embodiment, and the motor control unit 30a includes the detection unit 132 a.
The detection processing unit 13b detects the output current of the ac signal during a period of the detection signal having a larger duty ratio of the first detection signal and the second detection signal. The detection processing unit 13b includes a detection preprocessing unit 131a and a detection unit 132 a.
The detection preprocessor 131a includes the integrating circuits 40-1 to 40-6, and generates first detection signals (the detection signal UH, the detection signal VH, and the detection signal WH) from the outputs of the rogowski coils 11(11-1, 11-2, and 11-3). The detection pre-processing unit 131a generates second detection signals (detection signal UL, detection signal VL, and detection signal WL) from the output of the rogowski coil 12(12-1, 12-2, 12-3).
The detection unit 132a uses detection signals (detection signal UH, detection signal VH, detection signal WH, detection signal UL, detection signal VL, and detection signal WL) instead of the synthesized signals (U-phase current signal UC, V-phase current signal VC, and W-phase current signal WC) in the second embodiment, and performs the same processing as the detection unit 132. The detection unit 132a detects the output current of the ac signal during a period of the detection signal having the larger duty ratio of the first detection signal and the second detection signal.
That is, the detection unit 132a acquires the voltage of the first detection signal and the voltage of the second detection signal via the ADC, compares the duty ratio of the first detection signal and the duty ratio of the second detection signal, and adopts the voltage value having the larger duty ratio as the current value.
The operation of the current detection device 10b according to the present embodiment is the same as that of the second embodiment shown in fig. 12 except that the first detection signal (detection signal UH, detection signal VH, and detection signal WH) and the second detection signal (detection signal UL, detection signal VL, and detection signal WH) are used as they are instead of the combined signal (U-phase current signal UC, V-phase current signal VC, and W-phase current signal WC), and therefore, the description thereof is omitted.
As described above, in the current detection device 10b and the motor control device 1b according to the present embodiment, the detection processing unit 13b detects the output current of the ac signal during the period of the detection signal having the larger duty ratio of the first detection signal and the second detection signal.
As described above, the current detection device 10b and the motor control device 1b according to the present embodiment can achieve the same effects as those of the second embodiment, reduce the influence of ringing, and realize accurate current detection.
The present invention is not limited to the above embodiments, and may be modified within a range not departing from the gist of the present invention.
For example, although the current detection device 10(10a, 10b) is included in the motor control device 1(1a, 1b) and detects the current for controlling the driving of the motor 3 in the above embodiments, the present invention is not limited thereto. For example, the current detection device 10(10a, 10b) may be applied to current detection of an inverter unit other than the motor control device 1(1a, 1b) such as a power supply device.
In the first embodiment, the detection processing unit 13 outputs a signal obtained by converting a current waveform into a voltage, and the motor control unit 30 obtains a current value by an ADC (analog to digital converter), not shown, but the present invention is not limited thereto. The signals for converting the current waveform into a voltage include a U-phase current signal UC, a V-phase current signal VC, a W-phase current signal WC, an input current signal BTC, a U-phase negative current signal UMC, a V-phase negative current signal VMC, a W-phase negative current signal WMC, and the like. For example, the detection processing unit 13 may include an ADC. That is, the detection processing unit 13 may have a part of the functions of the motor control unit 30. The motor control unit 30 may have a part or all of the functions of the detection processing unit 13.
In the second and third embodiments, the detection processing unit 13a (13b) includes the motor control unit 30a having the detection unit 132(132a), but is not limited thereto. For example, the detection unit 132(132a) may be provided outside the motor control unit 30 a. That is, the detection processing unit 13a (13b) may have a part of the functions of the motor control unit 30 a. The motor control unit 30a may have a part or all of the functions of the detection processing unit 13a (13 b).
In each of the above embodiments, the current detection device 10(10a, 10b) detects a current in accordance with a three-phase ac signal, but is not limited thereto, and may be applied to detection of a current smaller than three phases or 4 or more phases.
In each of the above embodiments, the functions of the detection processing units 13(13a, 13b) are realized by hardware processing of circuits such as the integrating circuit 40 and the adders (50, 51), but the present invention is not limited to this, and some or all of the functions of the detection processing units 13(13a, 13b) may be realized by software processing.
Each of the configurations of the motor control devices 1(1a, 1b) has a computer system therein, and the motor control devices 1(1a, 1b) are created by recording a program for realizing the functions of each of the configurations of the motor control devices 1 in a computer-readable storage medium, reading the program stored in the medium into the computer system, and executing the program. The "reading a program stored in a storage medium into a computer system and executing" referred to herein includes installing the program in the computer system. The "computer system" includes hardware such as an OS and peripheral devices.
The "computer system" may also include a plurality of computer apparatuses connected via a network including a communication line such as the internet, a WAN, a LAN, a dedicated line, or the like. The "computer-readable storage medium" refers to a storage device such as a flexible disk, a magneto-optical disk, a removable medium such as a ROM or a CD-ROM, or a hard disk built in a computer system. The storage medium storing the program may be a non-transitory storage medium such as a CD-ROM.
The storage medium may include an internal or external storage medium that can be accessed from a distribution server to distribute the program. The program may be divided into a plurality of programs and downloaded at different time periods, and then the respective configurations of the motor control devices 1(1a, 1b) may be combined, or the respective distribution servers for distributing the divided programs may be independent of each other. The "computer-readable storage medium" also includes a medium that holds a program for a certain period of time, such as a server when the program is transmitted via a network and a volatile memory (RAM) inside a computer system of a client. The above-described program may be used to implement a part of the above-described functions. Or may be a so-called differential file (differential program) that can realize the above-described functions in combination with a program already stored in the computer system.
Some or all of the above functions may be implemented as an integrated circuit such as an LSI (Large Scale Integration). The above functions may be individually processed, or may be integrated with a part or all of them to be processed. The method of realizing the integration is not limited to the LSI, and may be realized by a dedicated circuit or a general-purpose processor. Since a technology for realizing an integrated circuit instead of an LSI appears due to the progress of semiconductor technology, an integrated circuit based on this technology may be used.
[ notation ] to show
1. 1a, 1b motor control device
2 D.C. power supply
3 electric machine
4 smoothing capacitor
10. 10a, 10b current detection device
11. 11-1, 11-2, 11-3, 12-1, 12-2, 12-3 helical coil
13. 13a, 13b detection processing unit
20 inverter part
21. 21-1, 21-2, 21-3, 22-1, 22-2, 22-3 switching elements
30. 30a motor control part
40. 40-1, 40-2, 40-3, 40-4, 40-5 and 40-6 integrating circuits
41 resistance
42 operational amplifier
43 capacitor
44 reset switch
50. 50-1, 50-2, 50-3, 50-4, 50-5, 50-6, 51 summers
131. 131a detection preprocessing section
132. 132a detection unit.

Claims (11)

1. A current detection device for detecting a current flowing through an inverter unit having a first switching element and a second switching element connected in series and generating an AC signal, comprising:
a first rogowski coil for detecting a current flowing through the first switching element;
a second rogowski coil for detecting a current flowing through the second switching element; and
and a detection processing unit that generates a synthesized signal obtained by adding a first detection signal obtained by integrating the output of the first helical coil and a second detection signal obtained by integrating the output of the second helical coil, and detects the output current of the ac signal based on the synthesized signal.
2. The current detection device according to claim 1, wherein:
wherein the inverter unit includes a plurality of groups of the first switching elements and the second switching elements, and generates alternating current signals having different phases corresponding to the plurality of groups of the first switching elements and the second switching elements,
the current detection device includes the first and second helical coils corresponding to the plurality of groups, respectively,
the detection processing unit generates the composite signal corresponding to each of the plurality of groups, and detects the output current of the alternating current signal having the different phase from each other based on the composite signal.
3. The current detection device according to claim 2, wherein:
wherein the detection processing unit detects a total value obtained by summing the first detection signals corresponding to the plurality of groups as the input current of the inverter unit.
4. The current detection device according to claim 2 or 3, wherein:
wherein the detection processing section detects a negative current of the alternating current signal of one phase in a negative current cycle among the plurality of alternating current signals having mutually different phases, from an output current of the other phase than the one phase among the plurality of alternating current signals.
5. A current detection device for detecting a current flowing through an inverter unit having a first switching element and a second switching element connected in series and generating an AC signal, comprising:
a first solenoid coil for detecting a current flowing through the first switching element;
a second solenoid for detecting a current flowing through the second switching element; and
and a detection processing unit that detects an output current of the ac signal based on one of a first detection signal obtained by integrating an output of the first rogowski coil and a second detection signal obtained by integrating an output of the second rogowski coil, the one having a larger duty ratio and causing the switching element to be in an on state.
6. The current detection device according to claim 5, wherein:
wherein the detection processing section generates a composite signal obtained by adding the first detection signal and the second detection signal, and detects the output current of the alternating current signal with respect to the composite signal during a period of the detection signal of which the duty ratio is larger of the first detection signal and the second detection signal.
7. The current detection device according to claim 5, wherein:
wherein the detection processing section detects the output current of the alternating current signal during a period of the one of the first detection signal and the second detection signal whose duty ratio is larger.
8. The current detection device according to any one of claims 1 to 7, characterized in that:
wherein the detection processing unit includes:
a first integrating circuit having a reset function for integrating an output of the first loop coil; and
and a second integration circuit having a reset function for integrating the output of the second loop coil.
9. A motor control apparatus, comprising:
the current detection device according to any one of claims 1 to 8;
an inverter unit configured to supply the alternating current signal to a motor as a drive signal; and
and a motor control unit for controlling switching of the first switching element and the second switching element based on the output current detected by the current detection device.
10. A current detection method for detecting a current flowing through an inverter unit having a first switching element and a second switching element connected in series and generating an ac signal, comprising:
a first generation step in which a detection processing unit integrates an output of a first solenoid that detects a current flowing through the first switching element, and generates a first detection signal;
a second generation step in which the detection processing unit integrates an output of a second solenoid that detects a current flowing through the second switching element, and generates a second detection signal; and
a detection processing step of generating a composite signal obtained by adding the first detection signal generated in the first generation step and the second detection signal generated in the second generation step, and detecting an output current of an alternating current signal from the composite signal.
11. A current detection method for detecting a current flowing through an inverter unit having a first switching element and a second switching element connected in series and generating an ac signal, comprising:
a first generation step in which a detection processing unit integrates an output of a first solenoid that detects a current flowing through the first switching element, and generates a first detection signal;
a second generation step in which the detection processing unit integrates an output of a second solenoid that detects a current flowing through the second switching element, and generates a second detection signal; and
a detection processing step of detecting an output current of an ac signal based on one of the first detection signal generated in the first generation step and the second detection signal generated in the second generation step, the one having a larger duty ratio for turning on the switching element.
CN202080057159.0A 2019-10-04 2020-10-02 Current detection device, motor control device, and current detection method Pending CN114222926A (en)

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